JP4511285B2 - Wave plate and optical device using the same - Google Patents

Description

  The present invention relates to a wave plate and an optical device using the same, and more particularly to a wave plate having a linear grating groove pattern and an optical device using the wave plate.

  Conventionally, a wave plate having a linear lattice groove pattern is known. As a method for manufacturing the linear grating groove pattern constituting the conventional wave plate described above, a method using a photolithography technique and an etching technique is known (for example, see Non-Patent Document 1).

  FIG. 93 is a perspective view showing a concept of a wave plate having a conventional linear grating groove pattern. In the conventional wave plate 200, as shown in FIG. 93, a linear lattice groove pattern is formed on the glass substrate 201. This lattice groove pattern is composed of an air layer 202 and a substrate material layer 203 having a width a made of the same material as that of the glass substrate 201, and has a period P equal to or less than the wavelength of light. Note that the refractive index of the air layer 202 is 1, and the refractive index of the substrate material layer 203 (glass substrate 201) is n. When light is incident on the grating groove pattern of the wave plate 200, the refractive index of the wave plate 200 is an effective refractive index obtained by mixing the refractive index 1 of the air layer 202 and the refractive index n of the substrate material layer 203. Refractive index.

  FIG. 94 is a correlation diagram showing the relationship between the effective refractive index and the duty ratio of the conventional wave plate shown in FIG. The vertical axis of FIG. 94 represents the effective refractive index, and the horizontal axis represents the duty ratio (= a) which is the ratio of the width a of the substrate material layer 203 to the period P of the grating groove pattern shown in FIG. / P). “TE” in FIG. 94 indicates light whose polarization direction is parallel to the direction in which the grating groove pattern extends, as shown in FIG. Further, “TM” indicates light whose polarization direction is orthogonal to the direction in which the grating groove pattern extends, as shown in FIG.

  Referring to FIG. 94, when the duty ratio of the grating groove pattern changes, the effective refractive index also changes. In this case, the effective refractive index of light (TE) whose polarization direction is parallel to the direction in which the grating groove pattern extends is different from the effective refractive index of light (TM) whose polarization direction is orthogonal to the direction in which the grating groove pattern extends. Become. That is, as shown in FIG. 94, when the duty ratio is D1, the effective refractive index of TM is N1, and the effective refractive index of TE is N2. Such a characteristic that the effective refractive index differs depending on the polarization direction of light is called a birefringence characteristic.

As a method for manufacturing the linear grating groove pattern of the conventional wave plate 200 shown in FIG. 93, for example, a linear grating is formed by etching the surface of the glass substrate using a photolithography technique and an etching technique. A method of forming a groove pattern is conceivable.
D. Hambach, G.M. Schneider and E.M. M.M. Gullikson “OPTICS LETTERS”, Vol. 26, no. 15, August 1, 2001, pp. 1200-1202

  However, when the linear grating groove pattern of the conventional wave plate 200 shown in FIG. 93 is formed using the photolithography technique and the etching technique, the depth is large and the groove width is uniform in the depth direction. It was difficult to form a lattice groove pattern having the same. Specifically, when the lattice groove pattern is formed deeply using photolithography technology and etching technology, as shown in FIG. 95, a lattice groove pattern having a trapezoidal cross section that is not uniform in the depth direction is formed. There is an inconvenience that the duty ratios of the upper part and the lower part of the grating groove pattern are different.

  By the way, a manufacturing method of a regular triangular triangular lattice pattern using an anodic oxidation method is conventionally known. This manufacturing method is described in, for example, H.H. Masuda et al. “Appl. Phys. Lett.”, Vol. 71 (19), 10 November 1997, pp. 2770-2772. Since the triangular lattice pattern manufacturing method disclosed in this document can form a triangular lattice pattern having deep and uniform pores, it has been proposed as one of the methods for manufacturing a two-dimensional photonic crystal. Specifically, in valve metals such as aluminum, titanium and tantalum, and semiconductors such as Si and GaAs, when an anode is energized in an acidic electrolyte, an oxide film having pores arranged perpendicular to the film surface is formed. It has the characteristic. In particular, an aluminum oxide film has material characteristics that the pores are easily arranged in a triangular lattice pattern. By using this characteristic, a triangular lattice pattern having deep and uniform pores can be formed.

  96 to 99 are cross-sectional views for explaining a manufacturing process of a triangular lattice pattern using the conventional anodic oxidation method, and FIG. 100 is a two-dimensional photonic formed using the conventional anodic oxidation method. It is the top view which showed the crystal | crystallization. Next, a manufacturing process of a triangular lattice pattern using a conventional anodic oxidation method will be described with reference to FIGS.

  In the conventional triangular lattice pattern manufacturing process using the anodic oxidation method, as shown in FIG. 96, convex portions 211a having a triangular lattice array are formed on the surface of the pressing member 221 made of a hard material such as SiC. . And the texturing process which presses the pressing member 211 on the surface of the aluminum material 211 is performed. As a result, as shown in FIG. 97, recesses 211 a having a triangular lattice arrangement are formed on the surface of the aluminum material 211. Next, the aluminum material 211 in which the recesses 211a are formed is oxidized in an electrolytic solution 222 as shown in FIG. In this case, platinum or the like is used as the cathode 223, and an aqueous solution of sulfuric acid, oxalic acid, phosphoric acid, or the like is used as the electrolytic solution 222. As a result, as shown in FIGS. 99 and 100, the aluminum oxide film (alumina) 212 having a triangular lattice-like arrangement and deep and uniform pores 212a starting from the recesses 211a (see FIG. 97) is self-generated. It is formed systematically. The pores 212a can be formed to have a depth of several hundred μm or more with respect to a submicron diameter.

  However, the triangular lattice pattern manufacturing process using the conventional anodic oxidation method described above has been known as a method for forming two-dimensional photonic crystal pores. For this reason, conventionally, no attempt has been made to form the grating groove pattern of the wave plate 200 as shown in FIG. 93 by the anodic oxidation method.

  As described above, conventionally, since it has been difficult to form a grating groove pattern having a large depth and a uniform groove width in the depth direction, the characteristics of the wave plate including the grating groove pattern are improved. There was a problem that it was difficult.

  Conventionally, a wave plate made of a birefringent material is also known. As a birefringent material constituting the wave plate, a crystal having a birefringent crystal, a birefringent resin, and the like are known. When light is incident on such a crystal or birefringent resin, the phase of the polarization component parallel to the optical axis of the crystal and the polarization component perpendicular to it can be shifted. Then, by setting the phase shift (phase difference) to be a predetermined value, crystal or birefringent resin can be used as a quarter wavelength plate or a half wavelength plate.

  101 and 102 are perspective views showing the concept of a quarter-wave plate and a half-wave plate made of quartz, respectively. First, referring to FIG. 101, the quarter-wave plate 230 made of the crystal 231 has the crystal 231 so that the phase difference between the polarization component parallel to the optical axis of the crystal and the polarization component perpendicular to the optical axis is about 90 °. The thickness of is set. When linearly polarized light is incident on this quarter-wave plate 230 made of crystal 231 at an angle of about 45 ° with respect to the optical axis, the phase difference between the two polarization components orthogonal to each other becomes about 90 °. Thereby, linearly polarized incident light is converted into circularly polarized outgoing light. Referring to FIG. 102, the half-wave plate 240 made of the crystal 241 has a quartz crystal so that the phase difference between the polarization component parallel to the optical axis of the incident light and the polarization component perpendicular to the optical axis is about 180 °. A thickness of 241 is set. Specifically, the crystal 241 has a thickness that is twice the thickness of the crystal 231 forming the quarter-wave plate 230 shown in FIG. When linearly polarized light is incident on the half-wave plate 240 made of quartz 241 at an angle of about 45 ° with respect to the optical axis, the phase difference between the two polarization components orthogonal to each other becomes about 180 °. As a result, the polarization direction of the linearly polarized incident light is rotated by about 90 °.

  However, as shown in FIGS. 101 and 102, the use of quartz as the wave plate has the following disadvantages. That is, the refractive index usually has a characteristic (wavelength dispersion characteristic) whose value varies depending on the wavelength of light. For this reason, for example, in a quarter-wave plate made of quartz designed to support light having a wavelength of about 633 nm, the wavelength of incident light is shifted from the design wavelength (about 633 nm) as shown in FIG. In this case, the phase difference between the two polarization components orthogonal to each other is greatly deviated from the vicinity of 90 °. Therefore, there is a problem that it is difficult to obtain a good phase conversion characteristic of a wavelength plate made of quartz for light having a wavelength other than the design wavelength.

  Further, when a wavelength plate made of quartz is used for the optical device, there is a problem that it is difficult to improve the characteristics of the optical device. Specifically, in a CD-R / DVD compatible optical pickup device that can be used for both recording to a CD-R (Compact Disk Recordable) and playback from a DVD (Digital Versatile Disk) as a conventional optical device, A semiconductor laser having a wavelength near 790 nm is used as the -R semiconductor laser, and a semiconductor laser having a wavelength near 650 nm is used as the DVD semiconductor laser. For this reason, when a common quarter-wave plate made of quartz having the characteristics shown in FIG. 103 is used for the CD-R semiconductor laser and the DVD semiconductor laser, a DVD having a wavelength near 650 nm. For a semiconductor laser, the conversion by a quarter-wave plate is satisfactorily performed, whereas for the CD-R semiconductor laser having a wavelength near 790 nm, the conversion by a quarter-wave plate is favorably performed. There is a disadvantage that it becomes difficult. As described above, if the conversion of the laser beam on the quarter wavelength plate is not performed well, a laser beam having a polarization direction other than the design value is generated. In this case, the laser beam is reflected by the polarization beam splitter, so that the laser beam returns to the CD-R semiconductor laser element. As a result, the light intensity noise (light intensity fluctuation) of the semiconductor laser element increases, which causes a problem that it is difficult to improve the characteristics of the CD-R / DVD compatible optical pickup device.

  In addition, in a liquid crystal projector device as a conventional optical device, in order to convert the polarization direction of white light having a wide wavelength region including red, green and blue components emitted from a light source into a single polarization direction. A half-wave plate is used. In this case, if a half-wave plate made of quartz having the same characteristics as those shown in FIG. 103 is used, the phase difference greatly deviates from around 180 ° depending on the wavelength. Therefore, there is an inconvenience that it is difficult to perform good conversion. Thus, in the conventional liquid crystal projector device, if the light conversion by the half-wave plate is not performed satisfactorily, the light having a polarization direction that cannot be incident on the liquid crystal panel increases, so that the light use efficiency is lowered. Inconvenience occurs. As a result, there is a problem that it is difficult to improve the characteristics of the liquid crystal projector device because color deviation and luminance decrease due to a decrease in light use efficiency occur.

  In the conventional CD-R / DVD compatible optical pickup device described above, a quarter wavelength plate composed of two transparent substrates and a birefringent resin sheet sandwiched between the two transparent substrates is used. There are many. The quarter-wave plate including the birefringent resin sheet has two birefringent resins so that the birefringence direction is slightly shifted in order to obtain the favorable phase conversion characteristics of the quarter-wave plate in a wide wavelength region. Sheets are stacked. However, since the birefringent resin sheet is inferior to quartz in terms of environmental resistance, it is difficult to use it as a quarter-wave plate for an in-vehicle CD-R / DVD compatible optical pickup device. In addition, it is difficult to use a half-wave plate including a birefringent resin sheet having inferior environmental resistance characteristics even in a liquid crystal projector device in which the inside of the device is heated to a high temperature by a light source.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to provide a wave plate capable of obtaining good phase conversion characteristics in a wide wavelength region. It is.

  Another object of the present invention is to provide an optical device including a wave plate capable of obtaining good phase conversion characteristics in a wide wavelength region.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, a wave plate according to a first aspect of the present invention includes a substrate, and an aluminum oxide film formed on the substrate and having a linear lattice groove pattern. And the duty ratio De, which is the ratio of the substantial width of the aluminum oxide film between adjacent grating groove patterns to the period L (μm), is defined by the following four formulas. It is set to a value within the range.

L ≦ 0.65
L ≧ 2 × 10 ⁻¹⁴ e ^{31.263 De}
L ≦ 6.0317De ² -10.352De + 5.0516
(De−0.85) ² /0.44 ² + (L−0.41) ² /0.39 ² ≦ 1
In the wave plate according to the first aspect, as described above, the period L (μm) and the duty ratio De of the linear lattice groove pattern of the aluminum oxide film constituting the wave plate are defined by the above four equations. When the wavelength plate is used as a quarter wavelength plate, the phase difference between two polarization components orthogonal to each other is obtained for a plurality of lights having different wavelengths. It can be in the vicinity of 90 °. When the wave plate is used as a half-wave plate, the phase difference between two polarization components orthogonal to each other can be set to around 180 ° for a plurality of lights having different wavelengths. As a result, good phase conversion characteristics can be obtained in a wide wavelength region. In addition, since the aluminum oxide film is an inorganic material, a wavelength plate excellent in environmental resistance can be obtained. Thereby, even if the wave plate including the aluminum oxide film having a linear lattice groove pattern is used under a high temperature condition, it is possible to suppress the deterioration of the characteristics of the wave plate.

  In this case, the period L (μm) and the duty ratio De within the first range are applied to light in at least the red and infrared wavelength regions. With such a configuration, good phase conversion characteristics can be obtained at least in the red and infrared wavelength regions.

  In the wave plate according to the first aspect, preferably, the period L (μm) and the duty ratio De of the linear grating groove pattern are further set to values within a second range defined by the following four expressions. Is set.

De ≧ 0.73
L ≦ 0.4
L ≧ 30.952 De ³ −74.751 De ² + 59.62De−15.328
L ≦ 3.0776De ² −5.1863De + 2.5772
If comprised in this way, a favorable phase conversion characteristic can be acquired in a wider wavelength range.

  In this case, the period L (μm) and the duty ratio De within the second range are applied to light in all the wavelength regions of red, infrared, and blue. If comprised in this way, a favorable phase conversion characteristic can be acquired in all the wavelength ranges of red, infrared, and blue.

  In the wavelength plate according to the first aspect, preferably, the aluminum oxide film has a plurality of holes, and a value obtained by multiplying the diameter of the largest hole among the plurality of holes by 0.5 is a reference value. In this case, the plurality of holes are classified into a first hole having a diameter larger than the reference value and a second hole having a diameter equal to or smaller than the reference value, and the period L (μm) of the lattice groove pattern is set to the plurality of first holes. This is the period of the lattice groove pattern consisting of holes. If the first hole and the second hole are classified according to the reference value as described above, the influence of the second hole on the phase conversion characteristics is reduced. Thereby, in the aluminum oxide film having a plurality of holes including the first hole and the second hole, by adjusting the period L (μm) of the lattice groove pattern composed of the plurality of first holes, it can be easily improved. A wave plate having phase conversion characteristics can be obtained.

  In this case, it is preferable that the lattice groove pattern including the plurality of first holes is configured by arranging a plurality of hole groups including a plurality of hole arrays including the plurality of first holes at predetermined intervals. The pattern period L (μm) is an average value of distances between lines in contact with the outermost ends on one side of adjacent hole groups. According to this configuration, in the lattice groove pattern in which a plurality of hole groups each including a plurality of hole arrays each including a plurality of first holes are arranged at a predetermined interval, the outermost edge on one side of the adjacent hole groups is in contact with the lattice groove pattern. By adjusting the average value of the distance between the lines (the period L (μm) of the grating groove pattern), a wave plate having good phase conversion characteristics can be easily obtained.

  A wave plate according to a second aspect of the present invention includes a substrate, a linear lattice groove pattern formed on the substrate, and a plurality of holes connected to each other, and a plurality of holes arranged at a predetermined interval. And a plurality of holes constituting one of the lattice groove pattern and the lattice hole pattern included in the aluminum oxide film are holes adjacent to each other in the first direction. The hole rows are arranged in a row with a distance between the centers of the intervals T (μm) to form the hole rows, and the hole rows are arranged in a second direction orthogonal to the first direction, more than the hole intervals T (μm). A plurality of elements are arranged with a period L (μm) which is a large interval, and the period L (μm) and the hole interval T (μm) are set to values within a first range defined by the following two expressions. Has been.

L ≦ 0.65
L ≧ −1.2018T ³ + 0.3022T ² + 1.2988T + 0.01
In the wave plate according to the second aspect, as described above, the period L (μm) and the hole interval T (μm) of either the lattice groove pattern or the lattice hole pattern of the aluminum oxide film constituting the wave plate are set. When the wave plate is used as a quarter wave plate by setting the value within the first range defined by the above two formulas, a plurality of lights having different wavelengths are orthogonal to each other. Thus, the phase difference between the two polarized components can be close to 90 °. When the wave plate is used as a half-wave plate, the phase difference between two polarization components orthogonal to each other can be set to around 180 ° for a plurality of lights having different wavelengths. As a result, good phase conversion characteristics can be obtained in a wide wavelength region. In addition, since the aluminum oxide film is an inorganic material, a wavelength plate excellent in environmental resistance can be obtained. Thereby, even if a wave plate including an aluminum oxide film having a grating groove pattern or a grating hole pattern is used under a high temperature condition, deterioration of the characteristics of the wave plate can be suppressed.

  In this case, the period L (μm) and the hole interval T (μm) in the first range are applied to light in at least the red and infrared wavelength regions. With such a configuration, good phase conversion characteristics can be obtained at least in the red and infrared wavelength regions.

  In the wave plate according to the second aspect, preferably, the period L (μm) and the hole interval T (μm) are further set to values within a second range defined by the following three expressions. .

L ≦ 0.4
L ≧ −440.16T ³ + 63.334T ² −3.4273T + 0.3439
L ≧ 0.35 (T−0.0825) ^0.434 +0.245
If comprised in this way, a favorable phase conversion characteristic can be acquired in a wider wavelength range.

  In this case, the period L (μm) and the hole interval T (μm) in the second range are applied to light in all the wavelength regions of red, infrared, and blue. If comprised in this way, a favorable phase conversion characteristic can be acquired in all the wavelength ranges of red, infrared, and blue.

  In the wave plate according to the second aspect, preferably, when a value obtained by multiplying the diameter of the largest hole among the plurality of holes by 0.5 is a reference value, the plurality of holes have a diameter larger than the reference value. A first hole having a diameter smaller than a reference value and a second hole having a diameter equal to or smaller than a reference value, and the period L (μm) of either the lattice groove pattern or the lattice hole pattern is a lattice groove pattern including a plurality of first holes. And a period of any one of the lattice hole patterns including the plurality of first holes. If the first hole and the second hole are classified according to the reference value as described above, the influence of the second hole on the phase conversion characteristics is reduced. Thereby, in the aluminum oxide film having a plurality of holes including the first hole and the second hole, the period L (μm) of one of the lattice groove pattern and the lattice hole pattern including the plurality of first holes is adjusted. Thus, a wave plate having good phase conversion characteristics can be easily obtained.

  In this case, preferably, one of the lattice groove pattern including the plurality of first holes and the lattice hole pattern including the plurality of first holes is a hole group including a plurality of hole arrays including the plurality of first holes. The period L (μm) of one of the grating groove pattern and the grating hole pattern is determined by the distance between the lines in contact with the outermost end on one side of the adjacent hole group. Average value. With this configuration, in either one of the lattice groove pattern and the lattice hole pattern in which a plurality of hole groups each including a plurality of hole arrays each including a plurality of first holes are arranged at a predetermined interval, Wavelengths having good phase conversion characteristics can be easily achieved by adjusting the average value of the distance between lines in contact with the outermost end on one side (the period L (μm) of either the grating groove pattern or the grating hole pattern). A board can be obtained.

  An optical apparatus according to a third aspect of the present invention is formed on a light source having a plurality of wavelength regions, a predetermined phase difference between two orthogonally polarized components of light from the light source, a substrate, and the substrate. And a wave plate including a metal oxide film having one of a linear grating groove pattern having a birefringence characteristic and a grating hole pattern having a birefringence characteristic.

  In the optical device according to the third aspect, as described above, a metal oxide having either a linear lattice groove pattern having a birefringence characteristic or a lattice hole pattern having a birefringence characteristic on the substrate. If this metal oxide film is formed using an anodic oxidation method by forming a film, a grating groove pattern and a grating hole pattern having a large depth and a uniform groove width and diameter in the depth direction can be obtained. Since it can be formed in a self-organized manner, a wave plate having a good grating groove pattern or grating hole pattern can be obtained. As a result, since the characteristics of the wave plate can be improved, the characteristics of the optical device including the wave plate can also be improved. Further, since the metal oxide film is an inorganic material, it is possible to obtain a wave plate having excellent environmental resistance. As a result, even if a wave plate including a metal oxide film having a linear grating groove pattern or a grating hole pattern is used in an optical device used under a high temperature condition, the deterioration of the characteristics of the wave plate is suppressed. Can do.

  In the optical device according to the third aspect, preferably, the metal oxide film includes an aluminum oxide film having a linear lattice groove pattern, and the period L (μm) of the linear lattice groove pattern and the period L (μm). The duty ratio De, which is the ratio of the substantial width of the aluminum oxide film between adjacent lattice groove patterns to (1), is set to a value within the first range defined by the following four equations.

L ≦ 0.65
L ≧ 2 × 10 ⁻¹⁴ e ^{31.263 De}
L ≦ 6.0317De ² -10.352De + 5.0516
(De−0.85) ² /0.44 ² + (L−0.41) ² /0.39 ² ≦ 1
With this configuration, when the wave plate is used as a quarter wave plate, the phase difference between two polarization components orthogonal to each other for a plurality of lights having different wavelengths can be close to 90 °. it can. When the wave plate is used as a half-wave plate, the phase difference between two polarization components orthogonal to each other can be set to around 180 ° for a plurality of lights having different wavelengths. As a result, an optical device including a wave plate having good phase conversion characteristics in a wide wavelength region can be obtained.

  In this case, the wave plate having the period L (μm) and the duty ratio De within the first range is used for light in at least the red and infrared wavelength regions. With such a configuration, good phase conversion characteristics can be obtained at least in the red and infrared wavelength regions.

  In the optical device according to the third aspect, preferably, the period L (μm) and the duty ratio De of the linear grating groove pattern are further set to values within a second range defined by the following four expressions. Is set.

De ≧ 0.73
L ≦ 0.4
L ≧ 30.952 De ³ −74.751 De ² + 59.62De−15.328
L ≦ 3.0776De ² −5.1863De + 2.5772
If comprised in this way, the favorable phase conversion characteristic of the wavelength plate which comprises an optical apparatus can be acquired in a wider wavelength range.

  In this case, the wave plate having the period L (μm) and the duty ratio De within the second range is used for light in all the wavelength regions of red, infrared, and blue. If comprised in this way, a favorable phase conversion characteristic can be acquired in all the wavelength ranges of red, infrared, and blue.

  In the optical device according to the third aspect, preferably, the metal oxide film includes a linear lattice groove pattern in which a plurality of holes are connected and a lattice hole pattern in which the plurality of holes are arranged at a predetermined interval. A plurality of holes including an aluminum oxide film having either one of the lattice groove pattern and the lattice hole pattern included in the aluminum oxide film are adjacent to each other in the first direction with a hole interval T (μm ) Are arranged in a row at a distance between the centers of each other to form a hole row, and the hole row is a gap larger than the hole gap T (μm) in the second direction orthogonal to the first direction. A plurality of periods L (μm) are arranged, and the period L (μm) and the hole interval T (μm) are set to values within a first range defined by the following two expressions.

L ≦ 0.65
L ≧ −1.2018T ³ + 0.3022T ² + 1.2988T + 0.01
With this configuration, when the wave plate is used as a quarter wave plate, the phase difference between two polarization components orthogonal to each other for a plurality of lights having different wavelengths can be close to 90 °. it can. When the wave plate is used as a half-wave plate, the phase difference between two polarization components orthogonal to each other can be set to around 180 ° for a plurality of lights having different wavelengths. As a result, an optical device including a wave plate having good phase conversion characteristics in a wide wavelength region can be obtained.

  In this case, a wave plate having a period L (μm) and a hole interval T (μm) within the first range is used for light in at least red and infrared wavelength regions. With such a configuration, good phase conversion characteristics can be obtained at least in the red and infrared wavelength regions.

  In the optical device according to the third aspect, preferably, the period L (μm) and the hole interval T (μm) are further set to values within a second range defined by the following three expressions. .

L ≦ 0.4
L ≧ −440.16T ³ + 63.334T ² −3.4273T + 0.3439
L ≧ 0.35 (T−0.0825) ^0.434 +0.245
If comprised in this way, the favorable phase conversion characteristic of the wavelength plate which comprises an optical apparatus can be acquired in a wider wavelength range.

  In this case, a wave plate having a period L (μm) and a hole interval T (μm) within the second range is used for light in all wavelength regions of red, infrared, and blue. If comprised in this way, a favorable phase conversion characteristic can be acquired in all the wavelength ranges of red, infrared, and blue.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First reference form)
Figure 1 is a perspective view showing a structure of a quarter-wave plate according to a first referential embodiment of the present invention. Referring to FIG. 1, the quarter-wave plate according to the first reference embodiment, by approximately 90 ° the phase difference between the parallel polarization component and the vertical polarization component to the optical axis (grating groove direction), optical It has a function of converting linearly polarized incident light inclined by about 45 ° with respect to the axis (lattice groove direction) into circularly polarized outgoing light. The quarter wave plate is an example of the “wave plate” in the present invention.

As a specific structure of the quarter wavelength plate according to the first reference embodiment, a transparent conductive film 2 made of ITO or ZnO is formed on a glass substrate 1 as shown in FIG. The glass substrate 1 is an example of the “substrate” in the present invention.

Here, in the first reference embodiment, an aluminum oxide film 3 having a linear lattice groove pattern is formed on the transparent conductive film 2. The linear lattice groove pattern of the aluminum oxide film 3 is formed by connecting the pores linearly. Further, the groove portions 3a of the linear lattice groove pattern of the aluminum oxide film 3 have a depth reaching the transparent conductive film 2 and are formed with a uniform width in the depth direction. In addition, a plurality of holes 3b may be formed on the surface of the aluminum oxide film 3 located between the groove portions 3a. The aluminum oxide film 3 is an example of the “metal oxide film” in the present invention.

  FIG. 2 is a graph showing the effective duty ratio and period range of a quarter-wave plate having good phase conversion characteristics for a plurality of lights having different wavelengths. FIG. 3 is an enlarged plan view of a grating groove pattern for explaining the definition of the effective duty ratio. 4 to 31 are simulation results showing the relationship between the wavelength and the phase difference for defining the range shown in FIG. Next, referring to FIG. 1 to FIG. 31, the effect of a linear grating groove pattern (¼ wavelength plate) made of an aluminum oxide film having good phase conversion characteristics for a plurality of lights having different wavelengths. A method for defining the range of the dynamic duty ratio and period will be described. Note that a range F1 in FIG. 2 indicates a phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared, and blue in the vicinity of 90 ° (within a range of 90 ° ± 10 °). It is a range that can be made. Further, a range F2 in FIG. 2 is such that the phase difference between two polarization components orthogonal to each other is at least 90 ° (within a range of 90 ° ± 10 °) with respect to light of at least red and infrared wavelengths. Is a possible range. The range F1 is an example of the “second range” in the present invention, and the range F2 is an example of the “first range” in the present invention.

First, the definition of the effective duty ratio De will be described. As shown in FIG. 3, when the effective groove width of the groove portion 3a of the linear lattice groove pattern is We1, and the period is L1, the effective duty ratio De is De = (L1−We1) / L1. Define in. The effective groove width We1 is defined as We1 = 3S1 ² / (3S1 + T1) where S1 is the maximum width of the groove 3a and T1 is the pitch of the pores to be connected.

  When the range F1 in FIG. 2 is defined, first, red, infrared, and red are respectively applied to each of the linear lattice groove patterns made of a plurality of aluminum oxide films having different effective duty ratios De and periods L1. The relationship between the wavelength and the phase difference when blue light was incident was simulated. Based on the simulation result, the effective duty ratio De and the period L1 in which the phase difference is within the allowable range in the red (660 nm), infrared (790 nm), and blue (405 nm) wavelength ranges are set to the range F1. In addition, in the wavelength region of blue (405 nm), the effective duty ratio De and the period L1 in which the phase difference is outside the allowable range are not included in the range F1. The effective duty ratio De and the value (coordinates) of the period L1 used in the above simulation are shown in Table 1 below. The red, infrared, and blue wavelengths were set to 660 nm, 790 nm, and 405 nm, respectively, and the allowable range of phase difference was set to 90 ° ± 10 °.

  Referring to Table 1 above, coordinate point A2 (De: 0.75, L1: 0.4), coordinate point A3 (De: 0.79, L1: 0.4), coordinate point A5 (De: 0. 85, L1: 0.385), coordinate point A6 (De: 0.9, L1: 0.4), coordinate point A7 (De: 0.95, L1: 0.4), coordinate point A10 (De: 0) .82, L1: 0.37), coordinate point A11 (De: 0.95, L1: 0.37) and coordinate point A13 (De: 0.88, L1: 0.35), respectively, FIG. As shown in FIGS. 6, 8, 9, 10, 13, 14, and 16, the phase difference is observed in all wavelength regions of red (660 nm), infrared (790 nm), and blue (405 nm). It was within the allowable range (90 ° ± 10 °). In this case, the film thickness (μm) of the aluminum oxide film is as follows: coordinate point A2: 1.90 μm, coordinate point A3: 2.55 μm, coordinate point A5: 3.13 μm, coordinate point A6: 3.87 μm, Coordinate point A7: 4.77 μm, coordinate point A10: 2.28 μm, coordinate point A11: 3.77 μm, and coordinate point A13: 2.90 μm.

  Also, the coordinate point A1 (De: 0.73, L1: 0.4), the coordinate point A4 (De: 0.85, L1: 0.395), the coordinate point A8 (De: 0.97, L1: 0. 4), coordinate point A9 (De: 0.8, L1: 0.37), coordinate point A12 (De: 0.97, L1: 0.37) and coordinate point A14 (De: 0.88, L1: 0) .34), as shown in FIG. 4, FIG. 7, FIG. 11, FIG. 12, FIG. 15 and FIG. 17, the phase difference is within an allowable range in the red (660 nm) and infrared (790 nm) wavelength regions. Although it was within (90 ° ± 10 °), the phase difference was outside the allowable range (90 ° ± 10 °) in the blue (405 nm) wavelength region. The film thicknesses of the aluminum oxide films in this case are as follows: coordinate point A1: 1.78 μm, coordinate point A4: 3.22 μm, coordinate point A8: 5.91 μm, coordinate point A9: 2.02 μm, coordinate point A12. : 5.06 μm and coordinate point A14: 2.86 μm.

  The coordinate points A2, A3, A5, A6, A7 in which the phase difference is within the allowable range (90 ° ± 10 °) in all wavelength regions of red (660 nm), infrared (790 nm), and blue (405 nm). , A10, A11, and A13, and coordinate points A1, A4, A8, A9, A12, and A14 in which the phase difference is outside the allowable range (90 ° ± 10 °) only in the blue (405 nm) wavelength region. The range F1 shown in FIG. 2 was defined by the following four formulas so as not to include them.

De ≧ 0.73 (1)
L1 ≦ 0.4 (2)
L1 ≧ 30.852De ³ −74.751De ² + 59.62De-15.328 (3)
L1 ≦ 3.0776De ² −5.1863De + 2.5772 (4)
Note that the above formulas (1) and (2) define the straight line portion F11 at the top of the range F1 shown in FIG. Further, the above-described formulas (3) and (4) respectively define the lower curved portion F12 and the upper concave portion F13 of the range F1 shown in FIG.

  Next, when defining the range F2 in FIG. 2, first, red and infrared are respectively applied to each of the linear lattice groove patterns made of a plurality of aluminum oxide films having different effective duty ratios De and periods L1. The relationship between the wavelength and the phase difference when the light of the wavelength was incident was simulated. Based on the simulation result, in the wavelength range of red (660 nm) and infrared (790 nm), the effective duty ratio De and the period L1 that make the phase difference within the allowable range are included in the range F2, and red (660 nm). ) And the infrared (790 nm) wavelength region, the effective duty ratio De and the period L1 in which the phase difference is outside the allowable range are not included in the range F2. The effective duty ratio De and the value (coordinates) of the period L1 used in the above simulation are shown in Table 2 below. The red and infrared wavelengths were set to 660 nm and 790 nm, respectively, and the allowable range of the phase difference was set to 90 ° ± 10 °.

  Referring to Table 2 above, coordinate point B2 (De: 0.52, L1: 0.65), coordinate point B3 (De: 0.76, L1: 0.65), coordinate point B6 (De: 0. 96, L1: 0.65), coordinate point B8 (De: 0.86, L1: 0.6), coordinate point B10 (De: 0.44, L1: 0.4), coordinate point B12 (De: 0) .5, L1: 0.2) and coordinate point B13 (De: 0.9, L1: 0.04), FIG. 19, FIG. 20, FIG. 23, FIG. 25, FIG. 27, FIG. As shown in FIG. 4, the phase difference is within the allowable range (90 ° ± 10 °) in the red (660 nm) and infrared (790 nm) wavelength regions. In this case, the thickness (μm) of the aluminum oxide film is as follows: coordinate point B2: 1.60 μm, coordinate point B3: 3.01 μm, coordinate point B6: 10.27 μm, coordinate point B8: 4.28 μm, Coordinate point B10: 1.06 μm, coordinate point B12: 1.18 μm, and coordinate point B13: 2.46 μm.

  Also, coordinate point B1 (De: 0.48, L1: 0.65), coordinate point B4 (De: 0.8, L1: 0.65), coordinate point B5 (De: 0.92, L1: 0. 65), coordinate point B7 (De: 0.86, L1: 0.62), coordinate point B9 (De: 0.4, L1: 0.4), coordinate point B11 (De: 0.46, L1: 0) .2) and coordinate point B14 (De: 0.94, L1: 0.04), as shown in FIG. 18, FIG. 21, FIG. 22, FIG. 24, FIG. In the wavelength region of (660 nm) and infrared (790 nm), the phase difference is outside the allowable range (90 ° ± 10 °). In this case, the film thickness (μm) of the aluminum oxide film is as follows: coordinate point B1: 1.53 μm, coordinate point B4: 4.16 μm, coordinate point B5: 6.16 μm, coordinate point B7: 4.40 μm, The coordinate point B9 is 1.12 μm, the coordinate point B11 is 1.21 μm, and the coordinate point B14 is 2.61 μm.

  Then, in the red (660 nm) and infrared (790 nm) wavelength regions, the coordinate points B2, B3, B6, B8, B10, B12 and B13 whose phase difference is within the allowable range (90 ° ± 10 °) are included. 2 and the following four formulas so as not to include coordinate points B1, B4, B5, B7, B9, B11 and B14 whose phase difference is outside the allowable range (90 ° ± 10 °). Range F2 was defined.

L1 ≦ 0.65 (5)
L1 ≧ 2 × 10 ⁻¹⁴ e ^{31.263 De} (6)
L1 ≦ 6.0317De ² -10.352De + 5.0516 (7)
(De−0.85) ² /0.44 ² + (L1−0.41) ² /0.39 ² ≦ 1 (8)
It should be noted that the above formula (5), formula (6), formula (7) and formula (8) are respectively the straight line portion F21 in the upper part of the range F2 shown in FIG. A concave portion F23 and a lower left curved portion F24 are defined.

Here, in the first reference embodiment, the effective duty ratio De and the period L1 of the linear lattice groove pattern of the aluminum oxide film 3 (see FIG. 1) are expressed by the above four formulas (1) to (4). It is set to a value within the specified range F1 (for example, De: 0.88, L1: 0.38 (coordinate point P in FIG. 2)). That is, in the first reference form (coordinate point P in FIG. 2), the phase difference is within an allowable range (90 ° ± 10 in all wavelength regions of red (660 nm), infrared (790 nm), and blue (405 nm). °) within. FIG. 32 shows experimental results when the effective duty ratio De and the cycle L1 are set to 0.88 and 0.38 (coordinate point P in FIG. 2), respectively. In this case, the film thickness (μm) is the coordinate point P: 3.35 μm.

In the first reference embodiment, as described above, the effective duty ratio De and the period L1 of the linear lattice groove pattern of the aluminum oxide film 3 constituting the quarter-wave plate are expressed by four equations (1) to ( 4) by setting the values within the range F1 defined by (for example, De: 0.88, L1: 0.38 (coordinate point P in FIG. 2)), all red, infrared and blue The phase difference between two polarization components orthogonal to each other with respect to the wavelength of light can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °). As a result, a quarter-wave plate having good phase conversion characteristics in a wide wavelength region can be obtained. Moreover, since the aluminum oxide film 3 is an inorganic material, a quarter wavelength plate excellent in environmental resistance can be obtained. Thereby, even if the quarter wavelength plate containing the aluminum oxide film 3 having a linear lattice groove pattern is used under a high temperature condition, the deterioration of the characteristics of the quarter wavelength plate can be suppressed.

FIGS. 33 39 are cross-sectional and plan views for explaining a first example of a manufacturing process of the quarter-wave plate according to the reference embodiment shown in FIG. Next, with reference to FIGS. 33 to 39 to describe an example of a manufacturing process of quarter-wave plate according to the first reference embodiment.

  First, as shown in FIG. 33, a transparent conductive film 2 and an aluminum film 4 made of ITO or ZnO are sequentially formed on a glass substrate 1 by vapor deposition.

  Next, as shown in FIG. 34, in order to perform the texturing process, convex portions 11a having a regular arrangement are formed on the surface of the pressing member 11 made of a hard material such as SiC. At this time, as shown in FIG. 35, the dot rows of the recesses 4a formed on the surface of the textured aluminum film 4 are arranged in a row of triangular lattice patterns 4b arranged in a plurality of rows indicated by broken lines. The convex part 11a (refer FIG. 34) of the pressing member 11 is formed so that it may be formed. Then, as shown in FIG. 34, by performing a texturing process that presses the pressing member 11 against the surface of the aluminum film 4, the dot rows of the recesses 4 a having the arrangement shown in FIG. 35 are formed on the surface of the aluminum film 4. Form.

  Next, as shown in FIG. 36, by performing oxidation treatment on the aluminum film 4 in which the dot rows of the recesses 4a (see FIG. 35) are formed using an anodic oxidation method, holes corresponding to the dot rows (see FIG. 36). (Not shown). Specifically, the surface of the aluminum film 4 as the anode or the surface of the glass substrate 1 and the surface of the cathode 12 made of platinum are arranged to face each other. Then, in the phosphoric acid aqueous solution 13 having a concentration of about 0.05M, an oxidation treatment of about 3 hours is performed by applying a voltage of about 160V. At this time, a voltage is applied to the aluminum film 4 via the transparent conductive film 2 formed between the glass substrate 1 and the aluminum film 4. Thereby, since voltage can always be applied to the aluminum film 4 during the oxidation treatment, inconveniences such as remaining unoxidized aluminum film 4 even when the surface of the glass substrate 1 is uneven are prevented. Can do. Thereby, an aluminum oxide film (not shown) having fine holes is formed in a self-organized manner. In the fine holes formed by this anodizing treatment, when the maximum distance between adjacent holes is U and the anodizing voltage is Va, the relational expression U = 0.0025 Va (μm) may be established. Are known. This relational expression (U = 0.0025Va) is, for example, H.264. Masuda et al. “Jpn. J. Appl. Phys.”, Vol. 37, 1998, pp. L1340-L1342 and the like.

  Thereafter, using an aqueous solution containing about 5 wt% phosphoric acid, holes (not shown) corresponding to the dot rows formed by the anodizing treatment are enlarged by wet etching at about 30 ° C. At this time, as shown in FIGS. 37 and 38, since the holes corresponding to the dot rows are enlarged and adjacent holes are connected, the aluminum oxide film 3 located in the formation region of the groove 3a can be easily formed almost completely. Can be removed. In this way, the aluminum oxide film 3 having a linear lattice groove pattern is formed. The linear lattice groove pattern of the aluminum oxide film 3 is formed so that the depth of the groove 3a reaches the transparent conductive film 2, and the width of the groove 3a is formed uniformly in the depth direction. A plurality of holes 3b are formed on the surface of the aluminum oxide film 3 located between the groove portions 3a. Although this hole 3b is not preferable, as shown in FIG. 39, the triangular lattice pattern 4b in which the concave portion 4a is not formed due to the distortion of the concave portion 4a formed by texturing and the distortion due to anodization (see FIG. 35). It is thought that it is formed at a position corresponding to.

In the manufacturing process of the first reference embodiment, as described above, the aluminum oxide film 3 having a linear lattice groove pattern is formed by using the anodizing method, so that the depth is large and in the depth direction. Since a grating groove pattern having a uniform groove width can be formed in a self-organized manner, a quarter wavelength plate having a good grating groove pattern can be obtained.

FIG. 40 is a schematic diagram showing an optical system of a CD-R / DVD compatible optical pickup device as an optical device including the quarter-wave plate according to the first reference embodiment shown in FIG. Next, referring to FIG. 40, the structure of an optical system of a CD-R / DVD compatible optical pickup device including a quarter-wave plate according to the first reference embodiment will be described as shown in FIG.

As shown in FIG. 40, the optical system of this CD-R / DVD compatible optical pickup apparatus includes a CD-R semiconductor laser element 21a and a DVD semiconductor laser element 21b, diffraction gratings 22a and 22b, and a polarization beam splitter 23a. And 23b, a quarter wavelength plate 24, a collimator lens 25, an objective lens 26, a cylindrical lens 27, and a light receiving element 28. As the quarter wavelength plate 24, the quarter wavelength plate according to the first reference embodiment shown in FIG. 1 is used. The CD-R semiconductor laser element 21a and the DVD semiconductor laser element 21b are examples of the “light source” of the present invention, and the quarter wavelength plate 24 is an example of the “wavelength plate” of the present invention. is there.

  The CD-R semiconductor laser element 21a and the DVD semiconductor laser element 21b are arranged so that laser light is emitted in a direction parallel to the recording / reproducing surface 30a of the optical disc 30, respectively. This CD-R semiconductor laser element 21a emits laser light having a wavelength near 790 nm (infrared) used in CD-R, and the DVD semiconductor laser element 21b is near 650 nm (red) used in DVD. A laser beam having a wavelength of is emitted. The laser beams emitted from the CD-R semiconductor laser element 21a and the DVD semiconductor laser element 21b have linearly polarized light perpendicular to the recording / reproducing surface 30a of the optical disk 30, respectively. The diffraction gratings 22a and 22b have a function of converting the laser light emitted from the CD-R semiconductor laser element 21a and the DVD semiconductor laser element 21b into three laser lights including a tracking error detection beam, respectively. is doing.

  The polarization beam splitters 23a and 23b reflect laser light having a polarization direction perpendicular to the recording / reproducing surface 30a of the optical disc 30 and parallel to the paper surface, and to the recording / reproducing surface 30a of the optical disc 30. It has a function of transmitting laser light in a polarization direction parallel to and perpendicular to the paper surface. Here, by using the polarization beam splitters 23a and 23b, unlike the case of using a half mirror, the laser light having a predetermined polarization direction can be branched by nearly 100%, so that the light utilization efficiency can be improved. The polarization beam splitter 23a functions only for laser light having a wavelength near 790 nm (infrared) used in the CD-R, and in the polarization direction for laser light having a wavelength other than the wavelength near 790 nm. It is transparent regardless. The polarization beam splitter 23b functions only for laser light having a wavelength near 650 nm (red) used in DVD, and transmits laser light having a wavelength other than the wavelength near 650 nm regardless of the polarization direction. To do.

  The collimator lens 25 and the objective lens 26 have a function of condensing the laser light that has passed through the quarter wavelength plate 24 onto the recording / reproducing surface 30a of the optical disc 30. The cylindrical lens 27 has a function of converting the laser light reflected by the recording / reproducing surface 30a of the optical disc 30 into a laser light including a focus error detection (astigmatism method) beam. The light receiving element 28 has a function of detecting the laser light reflected by the recording / reproducing surface 30a of the optical disc 30 as a tracking error signal, a focus error signal, and an HF (high frequency) signal.

Next, referring to FIG. 40, the operation of the optical system of the CD-R / DVD compatible optical pickup device including a quarter-wave plate according to the first reference embodiment will be described as shown in FIG.

  First, when a CD-R is used as the optical disc 30, a laser beam L10 having a wavelength near 790 nm (infrared) and having linearly polarized light parallel to the paper surface is emitted from the CD-R semiconductor laser element 21a. . The laser beam L10 is converted into three laser beams L10 including a tracking error detection beam by the diffraction grating 22a, and then enters the polarization beam splitter 23a. At this time, the direction of the laser beam L10 is changed in the direction of the optical disc 30 by the polarization beam splitter 23a. Then, the laser beam L10 whose direction is changed in the direction of the optical disc 30 is converted from linearly polarized light into circularly polarized light by the quarter wavelength plate 24, and then condensed by the collimator lens 25 and the objective lens 26. Thereafter, a signal is recorded on the recording / reproducing surface 30a of the optical disc 30 by the condensed laser beam L10.

  The phase of the laser beam L20 that has not been consumed for recording the signal on the recording / reproducing surface 30a of the optical disc 30 is reflected by the recording / reproducing surface 30a of the optical disc 30 to change by about 180 °. Thereafter, the laser light L20 reflected by the recording / reproducing surface 30a of the optical disk 30 is converted from circularly polarized light to linearly polarized light by the quarter wavelength plate 24. At this time, since the phase of the laser beam L20 is changed by about 180 °, it is converted into the laser beam L20 having linearly polarized light parallel to the recording / reproducing surface 30a of the optical disc 30 and perpendicular to the paper surface. Then, the laser beam L20 having linearly polarized light perpendicular to the paper surface sequentially enters the polarization beam splitters 23a and 23b. Here, since the polarization beam splitter 23a reflects only laser light having a polarization direction parallel to the paper surface, the laser light L20 does not reflect in the direction of the semiconductor laser element 21a for CD-R. Further, since the polarization beam splitter 23b functions only with respect to a laser beam having a wavelength near 650 nm (red), the laser beam L20 does not reflect in the direction of the DVD semiconductor laser element 21b. Thereafter, the laser beam L20 transmitted through the polarization beam splitters 23a and 23b is converted into a laser beam L20 including a focus error detection (astigmatism method) beam by the cylindrical lens 27, and then enters the light receiving element. Thereby, the laser beam L20 is detected as a tracking error signal, a focus error signal, and an HF (high frequency) signal.

  Further, when a DVD is used as the optical disc 30, the same operation as that when a CD-R is used as the optical disc 30 is performed. However, in the case where a DVD is used as the optical disc 30, laser light L30 having a wavelength near 650 nm (red) and linearly polarized light parallel to the paper surface is emitted from the semiconductor laser device 21b for DVD. In this case, the laser beam L30 is converted into three laser beams L30 including a tracking error detection beam by the diffraction grating 22b. Further, the direction of the laser beam L30 is changed in the direction of the optical disc 30 by the polarization beam splitter 23b.

In the optical system of the CD-R / DVD compatible optical pickup device, as described above, as a 1/4-wave plate 24, by using a quarter wavelength plate according to the first reference embodiment shown in FIG. 1, CD- For the laser light L10 and L30 having a wavelength near 790 nm (infrared) used for R and 650 nm (red) used for DVD, the phase conversion characteristics of the quarter-wave plate 24 are about 90 ° (90 ° ± (Within the range of 10 °), the conversion of the laser beams L10 and L30 in the quarter-wave plate 24 can be performed satisfactorily. For this reason, laser light having a polarization direction other than the design value is not generated. As a result, the laser beam L20 reflected by the recording / reproducing surface 30a of the optical disc 30 can be suppressed from being reflected by the polarization beam splitters 23a and 23b. In addition, feedback to the DVD semiconductor laser element 21b can be suppressed. As a result, an increase in light intensity noise (light intensity fluctuation) of the CD-R semiconductor laser element 21a and the DVD semiconductor laser element 21b is suppressed, thereby improving the characteristics of the CD-R / DVD compatible optical pickup device. be able to. Further, since the quarter wavelength plate including the aluminum oxide film 3 according to the first reference embodiment shown in FIG. 1 is excellent in environmental resistance, the quarter wavelength plate is compatible with an in-vehicle CD-R / DVD. Even when used in an optical pickup device, it is possible to suppress the deterioration of the characteristics of the quarter-wave plate.

(Second reference form)
Figure 41 is a perspective view showing a structure of a half-wave plate according to a second referential embodiment of the present invention. With reference to FIG. 41, in the second reference embodiment, unlike the first reference embodiment, an example in which the present invention is applied to a half-wave plate will be described.

In other words, half-wave plate according to the second reference embodiment, as shown in FIG. 41, by about 180 ° the phase difference between the parallel polarization component and the vertical polarization component to the optical axis, the optical axis On the other hand, it has a function of rotating the polarization direction of linearly polarized incident light inclined by about 45 ° with respect to about 90 °. The half-wave plate is an example of the “wave plate” in the present invention.

As a specific structure of the half-wave plate according to the second reference embodiment, a transparent conductive film 2 made of ITO or ZnO is formed on the glass substrate 1 as in the first reference embodiment.

Here, in the second reference embodiment, an aluminum oxide film 43 having a linear lattice groove pattern is formed on the transparent conductive film 2. The thickness of the aluminum oxide film 43 is set to twice the thickness of the aluminum oxide film 3 constituting the quarter-wave plate of the first reference embodiment shown in FIG. Thereby, the phase difference between the polarization component parallel to the optical axis of the incident light and the polarization component perpendicular to the optical axis can be doubled (about 180 °) as compared with the first reference mode (about 90 °). Further, the linear lattice groove pattern of the aluminum oxide film 43 is formed by connecting the pores in a straight line as in the first reference embodiment. Further, the groove 43a of the linear lattice groove pattern of the aluminum oxide film 43 has a depth reaching the transparent conductive film 2 and has a uniform width in the depth direction. In addition, a plurality of holes 43b may be formed on the surface of the aluminum oxide film 43 located between the groove portions 43a. The aluminum oxide film 43 is an example of the “metal oxide film” in the present invention.

Next, the effective duty ratio and period of a linear grating groove pattern (1/2 wavelength plate) made of an aluminum oxide film capable of obtaining good phase conversion characteristics for a plurality of lights having different wavelengths The range can be shown in the same range as the first reference embodiment shown in FIG. 2 if the allowable range of the phase difference is set to 180 ° ± 20 °. In this case, a range F1 in FIG. 2 indicates that the phase difference between two polarization components orthogonal to each other is around 180 ° (within a range of 180 ° ± 20 °) for light of all wavelengths of red, infrared, and blue. 2, and a range F2 in FIG. 2 indicates that the phase difference between two polarization components orthogonal to each other at least for red and infrared wavelengths is around 180 ° (180 ° ± 20). Within the range of °).

Here, in the second reference embodiment, the effective duty ratio De and the period L1 of the linear lattice groove pattern of the aluminum oxide film 43 are the same as the above-described four formulas (1) as in the first reference embodiment shown in FIG. ) To Formula (4), the values are within the range F1 (for example, De: 0.88, L1: 0.38 (coordinate point P in FIG. 2)). That is, in the second reference form (coordinate point P in FIG. 2), the phase difference is within an allowable range (180 ° ± 20 in all wavelength regions of red (660 nm), infrared (790 nm), and blue (405 nm). °) within.

In the second reference embodiment, as described above, the effective duty ratio De and the period L1 of the linear lattice groove pattern of the aluminum oxide film 43 constituting the half-wave plate are within the range F1 shown in FIG. By setting values (for example, De: 0.88, L1: 0.38 (coordinate point P in FIG. 2)), light of all wavelengths of red, infrared, and blue are orthogonal to each other. The phase difference between the two polarization components can be in the vicinity of 180 ° (within a range of 180 ° ± 20 °). As a result, a half-wave plate having good phase conversion characteristics in a wide wavelength region can be obtained. Moreover, since the aluminum oxide film 43 is an inorganic material, a half-wave plate excellent in environmental resistance can be obtained. Thereby, even if the half-wave plate including the aluminum oxide film 43 having the linear lattice groove pattern is used under a high temperature condition, the deterioration of the characteristics of the half-wave plate can be suppressed.

42 is a schematic diagram showing an optical system of a liquid crystal projector device as an optical device including the half-wave plate according to the second reference form shown in FIG. 41, and FIG. 43 is a liquid crystal projector shown in FIG. It is the schematic which showed the structure of the polarization conversion element of the optical system of an apparatus. Next, with reference to FIGS. 42 and 43, a description is given of the structure of an optical system of a liquid crystal projector device comprising half-wave plate according to the second reference embodiment shown in FIG. 41.

  As shown in FIG. 42, the optical system of the liquid crystal projector device includes a light source unit 51, an integrator lens 52, a polarization conversion element 53, total reflection mirrors 54a to 54d, a condenser lens 55, and dichroic mirrors 56a and 56b. Liquid crystal panels 57a to 57c, a dichroic prism 58, and a projection lens 59.

  The light source unit 51 includes a light source 51a including a metal halide lamp, a halogen lamp, a xenon lamp, and the like, and a reflector 51b. The reflector 51b has a function of setting the direction of white light having a wide wavelength range emitted from the light source 51a to a predetermined direction. The integrator lens 52 and the condenser lens 55 have a function of converting the unimodal intensity distribution of white light having a wide wavelength region emitted from the light source 51a into a flat intensity distribution. The integrator lens 52 has a structure in which a two-dimensional microlens array (not shown) is combined.

Further, the polarization conversion element 53 has a function of converting the polarization direction of light into a single polarization direction. As shown in FIG. 43, the polarization conversion element 53 includes a half-wave plate 61, a polarization beam splitter array 62 having a plurality of polarization separation surfaces 62a, and a light shielding plate 63. As the half-wave plate 61, the half-wave plate according to the second reference form shown in FIG. 41 is used. The half-wave plate 61 is an example of the “wave plate” in the present invention.

  As shown in FIG. 42, the total reflection mirrors 54a to 54d have a function of reflecting all light. The dichroic mirror 56a has a function of transmitting only red light and reflecting green light and blue light, and the dichroic mirror 56b has a function of transmitting only blue light and reflecting red light and green light. is doing. The liquid crystal panels 57a to 57c have a function of spatially modulating red light, green light, and blue light, respectively, and the dichroic prism 58 has a function of synthesizing spatially modulated red light, green light, and blue light. Have. The projection lens 59 has a function of projecting the combined red light, green light, and blue light on the screen.

Next, the operation of the optical system of the liquid crystal projector apparatus including the half-wave plate according to the second reference embodiment shown in FIG. 41 will be described with reference to FIGS.

  First, the direction of white light including red light R, green light G, and blue light B components emitted from the light source 51a is directed toward the integrator lens 52 by the reflector 51b. The white light including the red light R, the green light G, and the blue light B component passes through the integrator lens 52 and then enters the polarization conversion element 53. As a result, the polarization direction of the white light including the red light R, the green light G, and the blue light B component is converted into one uniform polarization direction.

  Specifically, as shown in FIG. 43, the white light emitted from the light source 51a (see FIG. 42) includes a plurality of lights having different polarization directions (for example, S-polarized light and P-polarized light). ing. When the S-polarized light and the P-polarized light are incident on the polarization beam splitter array 62, the S-polarized light is reflected by the polarization separation surface 62a and then reflected by the adjacent polarization separation surface 62a. The light is emitted out of the splitter array 62. On the other hand, the P-polarized light passes through the polarization separation surface 62 a and is then emitted out of the polarization beam splitter array 62. Thereafter, the P-polarized light is converted into S-polarized light by the half-wave plate 61. In this way, all the light incident on the polarization conversion element 53 is converted into S-polarized light.

  Then, as shown in FIG. 42, the white light including the red light R, the green light G, and the blue light B component converted into the linearly polarized light having one uniform polarization direction is changed in direction by the total reflection mirror 54a. After that, it passes through the condenser lens 55. White light including red light R, green light G, and blue light B components is converted from a unimodal intensity distribution into a flat intensity distribution by the integrator lens 52 and the condenser lens 55.

  Next, the red light R passes through the dichroic mirror 56a, and then is reflected by the total reflection mirror 54b, thereby being redirected in the direction of the liquid crystal panel 57a. Further, the green light G is reflected by the dichroic mirror 56a, and further reflected by the dichroic mirror 56b, whereby the direction is changed in the direction of the liquid crystal panel 57b. The blue light B is reflected by the dichroic mirror 56a and then passes through the dichroic mirror 56b. Thereafter, the blue light B is sequentially reflected by the total reflection mirrors 54c and 54d, thereby being redirected toward the liquid crystal panel 57c. As a result, the white light is separated into red light R, green light G, and blue light B, and enters the liquid crystal panels 57a to 57c, respectively. Then, the red light R, the green light G, and the blue light B spatially modulated by the liquid crystal panels 57 a to 57 c are combined by the dichroic prism 58. Thereafter, the combined red light R, green light G and blue light B are projected on the screen by the projection lens 59.

In the optical system of the liquid crystal projector device, as described above, the half-wave plate 61 according to the second reference form shown in FIG. The phase conversion characteristics of the half-wave plate 61 with respect to the blue light B can be maintained in the vicinity of 180 ° (within a range of 180 ° ± 20 °). Conversion of the light G and the blue light B can be performed satisfactorily. For this reason, light having a polarization direction other than the design value is not generated. Thereby, since the increase in the light which has the polarization direction which cannot enter into liquid crystal panels 57a-57c can be suppressed, the fall of the utilization efficiency of light can be suppressed. As a result, it is possible to suppress color deviation and luminance reduction due to a decrease in light utilization efficiency, and thus it is possible to improve the characteristics of the liquid crystal projector device. Further, since the half-wave plate including an aluminum oxide film 43 according to the second reference embodiment shown in FIG. 41 is excellent in environmental resistance, the half-wave plate, inside the apparatus becomes high by the light source 51a Even if it is used in a liquid crystal projector device, it is possible to suppress the deterioration of the characteristics of the half-wave plate.

(Third embodiment)
FIG. 44 is a perspective view showing the structure of a quarter-wave plate according to the third embodiment of the present invention. Referring to FIG. 44, in the third embodiment, unlike the first and second reference embodiments, a lattice hole composed of a plurality of pores arranged in a triangular lattice shape as an aluminum oxide film constituting a wave plate. A case where an aluminum oxide film having a pattern is used will be described. The wave plate according to the third embodiment is similar to the first reference embodiment in that the phase difference between the polarization component parallel to the optical axis (in the arrow Y direction) and the polarization component perpendicular to the optical axis is set to about 90 °. It has a function of converting linearly polarized incident light inclined by about 45 ° with respect to the axis (arrow Y direction) into circularly polarized outgoing light.

  As a specific structure of the quarter wavelength plate according to the third embodiment, a transparent conductive film 72 made of ITO or ZnO is formed on a glass substrate 71 as shown in FIG. The glass substrate 71 is an example of the “substrate” in the present invention.

  Here, in the third embodiment, an aluminum oxide film 73 having a lattice hole pattern composed of a plurality of pores 73 a arranged in a triangular lattice pattern is formed on the transparent conductive film 72. The plurality of pores 73a constituting the lattice hole pattern of the aluminum oxide film 73 are not connected to the pores 73a adjacent to each other in the arrow Y direction (the direction in which the optical axis extends) (a predetermined pore center distance (pore spacing). ) And arranged in a row along the arrow Y direction to form the pore row 73b. A plurality of the pore rows 73b are arranged in the arrow X direction orthogonal to the arrow Y direction at intervals (periods) larger than the pore interval (center-to-center distance) between adjacent pores 73a. The pores 73a have a depth that reaches the transparent conductive film 72 and have a uniform diameter in the depth direction. The aluminum oxide film 73 is an example of the “metal oxide film” in the present invention. The pore 73a is an example of the “hole” in the present invention, and the pore row 73b is an example of the “hole row” in the present invention.

  FIG. 45 is a graph showing the pore interval and period range of a quarter-wave plate having good phase conversion characteristics for a plurality of lights having different wavelengths. FIGS. 46 and 47 are enlarged plan views of a lattice hole pattern and a lattice groove pattern, respectively, for explaining the definition of the pore interval and the period. 48 to 79 are simulation results showing the relationship between the wavelength and the phase difference for defining the range shown in FIG. Next, referring to FIG. 44 to FIG. 79, the pore spacing of a lattice hole pattern (quarter wave plate) made of an aluminum oxide film having good phase conversion characteristics for a plurality of lights having different wavelengths, and A method for defining the period range will be described. Note that a range F3 in FIG. 45 indicates a phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared, and blue in the vicinity of 90 ° (within a range of 90 ° ± 10 °). It is a range that can be made. A range F4 in FIG. 45 is such that the phase difference between two polarization components orthogonal to each other is at least 90 ° (within a range of 90 ° ± 10 °) with respect to light of at least red and infrared wavelengths. Is a possible range. The range F3 is an example of the “second range” in the present invention, and the range F4 is an example of the “first range” in the present invention.

  First, with reference to FIG. 46 and FIG. 47, the definition of the pore interval and the period will be described. 46 shows a lattice hole pattern in which the pores 70a adjacent to each other in the arrow Y direction (the direction in which the optical axis extends) are separated from each other, and FIG. A lattice groove pattern in which the pores 70a adjacent to each other in the direction) are in contact with each other or overlapped with each other is illustrated. As shown in FIGS. 46 and 47, the pore interval T2 is the distance between the centers of the pores 70a adjacent in the arrow Y direction. The period L2 is the distance between the center lines of the pore rows 70b adjacent to each other in the arrow X direction orthogonal to the arrow Y direction. Further, it is assumed that the distance between the center lines of the pore rows 70b adjacent in the arrow X direction (period L2) is larger than the distance between the centers of the pores 70a adjacent in the arrow Y direction (pore interval T2). The diameter S2 of the pores 70a is preferably 0.7 times or more the pore interval T2. Thus, if the diameter S2 of the pore 70a is set to 0.7 times or more of the pore interval T2, a large birefringence occurs, and a phase difference near 90 ° is obtained with a thin aluminum oxide film. Easy. Further, if the pore interval T2 and the period L2 are the same value, the refractive index felt by the incident light is isotropic and birefringence does not occur. Therefore, it is necessary to set the pore interval T2 and the period L2 to different values. is there.

Then, when defining the range F3 in FIG. 45, first, red, infrared, and red for each of the lattice hole pattern and the lattice groove pattern made of a plurality of aluminum oxide films having different pore intervals T2 and periods L2, respectively. The relationship between the wavelength and the phase difference when blue light was incident was simulated. Based on the simulation results, in all wavelength regions of red (660 nm), infrared (790 nm), and blue (405 nm), the pore interval T2 and the period L2 at which the phase difference is within the allowable range are set to the range F3. In addition, in the wavelength region of blue (405 nm), the pore interval T2 and the period L2 at which the phase difference is outside the allowable range are not included in the range F3. Table 3 below shows the values (coordinates) of the pore interval T2 and the period L2 used in the above simulation. The red, infrared, and blue wavelengths were set to 660 nm, 790 nm, and 405 nm, respectively, and the allowable range of the phase difference was set to 90 ° ± 10 °, as in the first reference embodiment.

  Referring to Table 3 above, coordinate point C1 (T2: 0.01, L2: 0.4), coordinate point C2 (T2: 0.06, L2: 0.4), coordinate point C3 (T2: 0. 1, L2: 0.4), coordinate point C4 (T2: 0.16, L2: 0.4), coordinate point C5 (T2: 0.22, L2: 0.4), coordinate point C7 (T2: 0) .01, L2: 0.35), coordinate point C8 (T2: 0.14, L2: 0.35), coordinate point C11 (T2: 0.02, L2: 0.3), coordinate point C12 (T2: 0.09, L2: 0.3) and the coordinate point C15 (T2: 0.08, L2: 0.25), FIG. 48, FIG. 49, FIG. 50, FIG. 51, FIG. 52, FIG. As shown in FIG. 55, FIG. 58, FIG. 59 and FIG. 62, all wavelength regions of red (660 nm), infrared (790 nm) and blue (405 nm) are used. There, the phase difference becomes within the allowable range (90 ° ± 10 °) in the.

  Here, among the coordinate points C1 to C5, C7, C8, C11, C12, and C15 described above, the lattice patterns corresponding to the coordinate points C3, C4, C5, C8, and C12 are arrows as shown in FIG. It is a lattice hole pattern in which the pores 70a adjacent to each other in the Y direction (direction in which the optical axis extends) are separated. In addition, as shown in FIG. 47, the lattice pattern corresponding to the coordinate point C2 is a lattice groove pattern that is connected by contacting the adjacent pores 70a in the arrow Y direction (direction in which the optical axis extends). In addition, the lattice patterns corresponding to the coordinate points C1, C7, C11, and C15 are lattice groove patterns that are connected by overlapping the adjacent pores 70a in the arrow Y direction, as shown in FIG.

  In this case, the thickness (μm) of the aluminum oxide film is as follows: coordinate point C1: 3.71 μm, coordinate point C2: 4.49 μm, coordinate point C3: 4.40 μm, coordinate point C4: 3.22 μm, Coordinate point C5: 3.92 μm, coordinate point C7: 2.75 μm, coordinate point C8: 3.13 μm, coordinate point C11: 2.50 μm, coordinate point C12: 2.60 μm, and coordinate point C15: 1.77 μm.

  The pore diameter (μm) is as follows: coordinate point C1: 0.04 μm, coordinate point C2: 0.06 μm, coordinate point C3: 0.09 μm, coordinate point C4: 0.15 μm, coordinate point C5: 0.182 μm. Coordinate point C7: 0.04 μm, coordinate point C8: 0.13 μm, coordinate point C11: 0.03 μm, coordinate point C12: 0.086 μm and coordinate point C15: 0.09 μm. In this case, the pore diameter (S2) (see FIGS. 46 and 47) is set to 0.7 times or more of the pore interval T2.

  Further, the coordinate point C6 (T2: 0.24, L2: 0.4), the coordinate point C9 (T2: 0.15, L2: 0.35), the coordinate point C10 (T2: 0.01, L2: 0. 3), coordinate point C13 (T2: 0.1, L2: 0.3), coordinate point C14 (T2: 0.07, L2: 0.25) and coordinate point C16 (T2: 0.09, L2: 0) .25), as shown in FIG. 53, FIG. 56, FIG. 57, FIG. 60, FIG. 61, and FIG. 63, the phase difference is within an allowable range in the red (660 nm) and infrared (790 nm) wavelength regions. Although it was within (90 ° ± 10 °), the phase difference was outside the allowable range (90 ° ± 10 °) in the blue (405 nm) wavelength region.

  Here, among the coordinate points C6, C9, C10, C13, C14, and C16 described above, the lattice pattern corresponding to the coordinate points C6, C9, and C13 is shown in FIG. This is a lattice hole pattern in which the pores 70a adjacent to each other in the extending direction are separated. In addition, as shown in FIG. 47, the lattice pattern corresponding to the coordinate points C10, C14, and C16 is a lattice groove connected by overlapping pores 70a adjacent in the arrow Y direction (direction in which the optical axis extends). It is a pattern.

  In this case, the film thickness (μm) of the aluminum oxide film is as follows: coordinate point C6: 4.14 μm, coordinate point C9: 2.95 μm, coordinate point C10: 2.77 μm, coordinate point C13: 3.25 μm, The coordinate point C14 is 1.72 μm and the coordinate point C16 is 1.82 μm.

  The pore diameter (μm) is as follows: coordinate point C6: 0.198 μm, coordinate point C9: 0.14 μm, coordinate point C10: 0.04 μm, coordinate point C13: 0.09 μm, coordinate point C14: 0.08 μm. And coordinate point C16: 0.096 μm. In this case, the pore diameter (S2) (see FIGS. 46 and 47) is set to 0.7 times or more of the pore interval T2.

  The coordinate points C1, C2, C3, C4, and C5 at which the phase difference is within an allowable range (90 ° ± 10 °) in all wavelength regions of red (660 nm), infrared (790 nm), and blue (405 nm). , C7, C8, C11, C12 and C15, and the coordinate points C6, C9, C10, C13 in which the phase difference is outside the allowable range (90 ° ± 10 °) only in the blue (405 nm) wavelength region, The range F3 shown in FIG. 45 is defined by the following three formulas so as not to include C14 and C16.

L2 ≦ 0.4 (11)
L2 ≧ −440.16T2 ³ + 63.334T2 ² −3.4273T2 + 0.3439 (12)
L2 ≧ 0.35 (T2-0.0825) ^0.434 +0.245 (13)
Note that the above equation (11) defines the straight line portion F31 at the top of the range F3 shown in FIG. Further, the above equation (12) defines a curved portion F32 at the lower left of the range F3 shown in FIG. Further, the above equation (13) defines a curved portion F33 on the right side of the range F3 shown in FIG.

  Next, when defining the range F4 in FIG. 45, first, red and infrared are respectively applied to a lattice hole pattern and a lattice groove pattern made of a plurality of aluminum oxide films having different pore intervals T2 and periods L2. The relationship between the wavelength and the phase difference when the light of the wavelength was incident was simulated. Based on the simulation result, in the wavelength range of red (660 nm) and infrared (790 nm), the pore distance T2 and the period L2 at which the phase difference is within the allowable range are included in the range F4, and red (660 nm). In the wavelength region, the pore interval T2 and the period L2 at which the phase difference is outside the allowable range are not included in the range F4. Table 4 below shows the values (coordinates) of the pore interval T2 and the period L2 used in the above simulation. The red and infrared wavelengths were set to 660 nm and 790 nm, respectively, and the allowable range of the phase difference was set to 90 ° ± 10 °.

  Referring to Table 4 above, coordinate point D1 (T2: 0.01, L2: 0.65), coordinate point D2 (T2: 0.1, L2: 0.65), coordinate point D3 (T2: 0. 2, L2: 0.65), coordinate point D4 (T2: 0.3, L2: 0.65), coordinate point D5 (T2: 0.4, L2: 0.65), coordinate point D6 (T2: 0) .5, L2: 0.65), coordinate point D7 (T2: 0.62, L2: 0.65), coordinate point D9 (T2: 0.51, L2: 0.6), coordinate point D11 (T2: 0.3, L2: 0.4), coordinate point D13 (T2: 0.14, L2: 0.2) and coordinate point D15 (T2: 0.01, L2: 0.04), respectively, FIG. 65, 66, 67, 68, 69, 70, 72, 74, 76 and 78, red (660 nm) and infrared ( In the wavelength region of 90 nm), the phase difference becomes within the allowable range (90 ° ± 10 °) in the.

  Here, among the coordinate points D1 to D7, D9, D11, D13 and D15 described above, the lattice patterns corresponding to the coordinate points D2, D3, D4, D5, D6, D7 and D9 are as shown in FIG. , A lattice hole pattern in which the pores 70a adjacent to each other in the arrow Y direction (the direction in which the optical axis extends) are separated. In addition, as shown in FIG. 47, the lattice pattern corresponding to the coordinate points D11 and D13 is a lattice groove pattern that is connected by contacting the pores 70a adjacent to each other in the arrow Y direction (direction in which the optical axis extends). is there. In addition, as shown in FIG. 47, the lattice pattern corresponding to the coordinate points D1 and D15 is a lattice groove pattern that is connected by overlapping the adjacent pores 70a in the arrow Y direction.

  In this case, the thickness (μm) of the aluminum oxide film is as follows: coordinate point D1: 15.62 μm, coordinate point D2: 15.67 μm, coordinate point D3: 7.03 μm, coordinate point D4: 5.32 μm, Coordinate point D5: 7.06, coordinate point D6: 6.08 μm, coordinate point D7: 4.47 μm, coordinate point D9: 3.56 μm, coordinate point D11: 1.85 μm, coordinate point D13: 1.72 μm and coordinate point D15: 5.12 μm.

  The pore diameter (μm) is as follows: coordinate point D1: 0.04 μm, coordinate point D2: 0.08 μm, coordinate point D3: 0.172 μm, coordinate point D4: 0.26 μm, coordinate point D5: 0.30 μm. , Coordinate point D6: 0.40 μm, coordinate point D7: 0.52 μm, coordinate point D9: 0.44 μm, coordinate point D11: 0.30 μm, coordinate point D13: 0.14 μm and coordinate point D15: 0.04 μm. . In this case, the pore diameter (S2) (see FIGS. 46 and 47) is set to 0.7 times or more of the pore interval T2.

  Also, the coordinate point D8 (T2: 0.65, L2: 0.65), the coordinate point D10 (T2: 0.53, L2: 0.6), the coordinate point D12 (T2: 0.32, L2: 0. 4), at coordinate point D14 (T2: 0.15, L2: 0.2) and coordinate point D16 (T2: 0.03, L2: 0.04), FIG. 71, FIG. 73, FIG. 75, FIG. 77 and FIG. 79, the phase difference was outside the allowable range (90 ° ± 10 °) in the red (660 nm) wavelength region.

  Here, among the coordinate points D8, D10, D12, D14, and D16 described above, the lattice pattern corresponding to the coordinate points D8, D10, D12, and D14 is shown in FIG. This is a lattice hole pattern in which the pores 70a adjacent to each other in the extending direction are separated. Further, as shown in FIG. 47, the lattice pattern corresponding to the coordinate point D16 is a lattice groove pattern connected by overlapping the pores 70a adjacent to each other in the arrow Y direction (direction in which the optical axis extends).

  The film thickness (μm) of the aluminum oxide film in this case is as follows: coordinate point D8: 17.33 μm, coordinate point D10: 4.23 μm, coordinate point D12: 2.48 μm, coordinate point D14: 2.10 μm, and Coordinate point D16: 6.03 μm.

  The pore diameter (μm) is as follows: coordinate point D8: 0.56 μm, coordinate point D10: 0.46 μm, coordinate point D12: 0.30 μm, coordinate point D14: 0.14 μm, and coordinate point D16: 0.04 μm. It is. In this case, the pore diameter (S2) (see FIGS. 46 and 47) is set to 0.7 times or more of the pore interval T2.

  In the red (660 nm) and infrared (790 nm) wavelength regions, the coordinate points D1, D2, D3, D4, D5, D6, D7, D9, where the phase difference is within the allowable range (90 ° ± 10 °), Coordinate points D8, D10, D12, D14, and D16 that include D11, D13, and D15 and that have a phase difference outside the allowable range (90 ° ± 10 °) in the wavelength region of red (660 nm) are not included. As described above, the range F4 shown in FIG. 45 is defined by the following two equations.

L2 ≦ 0.65 (14)
L2 ≧ −1.2018T2 ³ + 0.3022T2 ² + 1.29888T2 + 0.01 (15)
It should be noted that the above equation (14) defines the straight line portion F41 at the top of the range F4 shown in FIG. Further, the above equation (15) defines a curved portion F42 on the right side of the range F4 shown in FIG.

  Here, in the third embodiment, the pore interval T2 and the period L2 of the lattice hole pattern of the aluminum oxide film 73 (see FIG. 44) are in a range defined by the above three formulas (11) to (13). It is set to a value in F3 (for example, T2: 0.10, L2: 0.35 (coordinate point Q in FIG. 45)). That is, in the third embodiment (coordinate point Q in FIG. 45), the phase difference is within an allowable range (90 ° ± 10 in all wavelength regions of red (660 nm), infrared (790 nm), and blue (405 nm). °) within. FIG. 80 shows experimental results when the pore interval T2 and the period L2 are set to 0.10 and 0.35 (coordinate point Q in FIG. 45), respectively. In this case, the film thickness (μm) and the pore diameter (μm) are 3.63 μm and 0.09 μm, respectively.

In the third embodiment, as described above, the pore interval T2 and the period L2 of the lattice hole pattern of the aluminum oxide film 73 constituting the quarter-wave plate are defined by the three equations (11) to (13). By setting the values within the range F3 (for example, T2: 0.10, L2: 0.35 (coordinate point Q in FIG. 45)), light of all wavelengths of red, infrared, and blue On the other hand, the phase difference between two polarization components orthogonal to each other can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °). As a result, a quarter-wave plate having good phase conversion characteristics can be obtained in a wide wavelength region as in the first reference embodiment.

  In the third embodiment, as described above, by using the aluminum oxide film 73 having a lattice hole pattern composed of a plurality of pores 73a arranged in a triangular lattice shape as the aluminum oxide film constituting the wave plate. If the aluminum oxide film 73 is formed by using the conventional anodic oxidation method, the plurality of pores 73a arranged in a triangular lattice shape are formed in a self-organized manner, so that they are easily arranged in a triangular lattice shape. In addition, an aluminum oxide film 73 having a lattice hole pattern composed of a plurality of pores 73a can be formed.

The remaining effects of the third embodiment are similar to those of the aforementioned first reference embodiment.

  Next, referring to FIG. 44, as a manufacturing process of the third embodiment, first, a transparent conductive film 72 made of ITO or ZnO and an aluminum film (not shown) are formed on a glass substrate 71 by vapor deposition. ) Are sequentially formed. Thereafter, the range F3 defined by the equations (11) to (13) or the range defined by the equations (14) and (15) using the process similar to the conventional one shown in FIGS. After forming recesses (not shown) arranged in a triangular lattice pattern on the surface of the aluminum film so as to have the pore interval T2 and the period L2 in F4, the aluminum film is oxidized. As a result, an aluminum oxide film 73 is formed which has a pore interval T2 and a period L2 in the range F3 or F4 and has a lattice hole pattern composed of a plurality of pores 73a arranged in a triangular lattice shape.

(Fourth embodiment)
FIG. 81 is a perspective view showing the structure of a half-wave plate according to the fourth embodiment of the present invention. Referring to FIG. 81, in the fourth embodiment, unlike the third embodiment, an aluminum oxide film having a lattice hole pattern made up of a plurality of pores arranged in a triangular lattice shape is used as a half-wave plate. The case where it uses for is demonstrated. Note that the wave plate according to the fourth embodiment, like the second reference embodiment described above, has an optical phase difference of about 180 ° between the polarization component parallel to the optical axis (in the direction of arrow Y) and the polarization component perpendicular to the optical axis. It has a function of rotating the polarization direction of linearly polarized incident light inclined by about 45 ° with respect to the axis (arrow Y direction) by about 90 °.

  As a specific structure of the half-wave plate according to the fourth embodiment, a transparent conductive film 72 made of ITO or ZnO is formed on a glass substrate 71 as in the third embodiment.

  Here, in the fourth embodiment, an aluminum oxide film 83 having a lattice hole pattern including a plurality of pores 83 a arranged in a triangular lattice pattern is formed on the transparent conductive film 72. The plurality of pores 83a constituting the lattice hole pattern of the aluminum oxide film 83 are narrow adjacent to the arrow Y direction (direction in which the optical axis extends), like the lattice hole pattern of the aluminum oxide film 73 of the third embodiment. The pore rows 83b are configured by being arranged in a line along the arrow Y direction with a predetermined distance between pore centers (pore spacing) so as not to be connected to the holes 83a. A plurality of the pore rows 83b are arranged in the arrow X direction orthogonal to the arrow Y direction at intervals (periods) larger than the pore interval (center-to-center distance) between adjacent pores 83a. The pores 83a have a depth that reaches the transparent conductive film 72 and have a uniform diameter in the depth direction. The aluminum oxide film 83 is an example of the “metal oxide film” in the present invention. The pore 83a is an example of the “hole” in the present invention, and the pore row 83b is an example of the “hole row” in the present invention.

  Further, the thickness of the aluminum oxide film 83 is set to twice the thickness of the aluminum oxide film 73 of the third embodiment. As a result, the phase difference between the polarization component parallel to the optical axis of the aluminum oxide film 83 (arrow Y direction) and the polarization component perpendicular to the optical axis is doubled (about 180 °) in the third embodiment (about 90 °). be able to.

  Next, the range of the pore interval and period of the lattice hole pattern (1/2 wavelength plate) made of an aluminum oxide film capable of obtaining good phase conversion characteristics for a plurality of lights having different wavelengths is as follows. If the allowable range of the phase difference is set to 180 ° ± 20 °, it can be shown in the same range as the third embodiment shown in FIG. In this case, a range F3 in FIG. 45 indicates that the phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared, and blue is around 180 ° (within a range of 180 ° ± 20 °). The range F4 in FIG. 45 indicates that the phase difference between two polarization components orthogonal to each other is at least 180 ° (180 ° ± 20) with respect to light of at least red and infrared wavelengths. Within the range of °). In the fourth embodiment, as in the third embodiment, the diameter (S2) of the pores 83a is preferably set to 0.7 times or more the pore interval T2.

  Here, in the fourth embodiment, the pore interval T2 and the period L2 of the lattice hole pattern of the aluminum oxide film 83 are the same as the above-described three formulas (11) to (3), as in the third embodiment shown in FIG. 13) (for example, T2: 0.10, L2: 0.35 (coordinate point Q in FIG. 45)). That is, in the fourth embodiment (coordinate point Q in FIG. 45), the phase difference is within an allowable range (180 ° ± 20 in all wavelength regions of red (660 nm), infrared (790 nm), and blue (405 nm). °) within.

In the fourth embodiment, as described above, the pore interval T2 and the period L2 of the lattice hole pattern of the aluminum oxide film 83 constituting the half-wave plate are set to values within the range F3 shown in FIG. 45 (for example, By setting T2: 0.10 and L2: 0.35 (coordinate point Q in FIG. 45), two polarization components orthogonal to each other for light of all wavelengths of red, infrared, and blue Can be in the vicinity of 180 ° (within a range of 180 ° ± 20 °). As a result, a half-wave plate having good phase conversion characteristics in a wide wavelength region can be obtained as in the second reference embodiment.

  The remaining effects of the fourth embodiment are similar to those of the aforementioned third embodiment.

(Fifth embodiment)
FIG. 82 is a plan view showing a grating pattern of a wave plate according to a fifth embodiment of the present invention.
Referring to FIG. 82, in the fifth embodiment, unlike the third and fourth embodiments, a plurality of large pores and a plurality of small pores are included, and one pore consisting of large pores is provided. A wave plate provided with an aluminum oxide film having a lattice hole pattern in which a row and one pore row composed of small pores are alternately arranged at a predetermined interval will be described.

  In the fifth embodiment, as shown in FIG. 82, the aluminum oxide film 81 constituting the wave plate has a plurality of large pores 81a having a diameter S31 and a diameter S32 smaller than the diameter S31 of the pores 81a. A plurality of small pores 81b are formed. A plurality of pores including the large pores 81a and the small pores 81b are arranged in a triangular lattice shape. The aluminum oxide film 81 is an example of the “metal oxide film” in the present invention. The pores 81a and 81b are examples of the “first hole” and the “second hole” in the present invention, respectively.

  Here, in the fifth embodiment, a plurality of large pores 81 a formed in the aluminum oxide film 81 constitute a lattice hole pattern for phase conversion of incident light. The plurality of large pores 81a constituting the lattice hole pattern are arranged along the arrow Y direction at a predetermined interval so as not to be connected to the pores 81a adjacent to the arrow Y direction (direction in which the optical axis extends). The pore rows 82 are arranged in a shape. A plurality of the pore rows 82 are arranged at predetermined intervals in the arrow X direction so as not to be connected to the pore rows 82 adjacent in the arrow X direction orthogonal to the arrow Y direction. Further, between the pore rows 82 adjacent in the arrow X direction, one pore row 83 composed of a plurality of small pores 81b is arranged. That is, one pore row 82 and one pore row 83 are alternately arranged at a predetermined interval in the arrow X direction. The pore row 82 is an example of the “hole row” in the present invention.

  Next, the definition of the pore interval T3 and the period L3 of the lattice hole pattern of the aluminum oxide film 81 constituting the wave plate according to the fifth embodiment will be described. The pore interval T3 is the distance between the centers of the large pores 81a adjacent in the arrow Y direction. The period L3 is the distance between the center lines of the pore rows 82 adjacent in the arrow X direction. That is, when defining the pore interval T3 and the period L3, attention is focused on only the large pore 81a without considering the small pore 81b.

  Next, the definition of the large pore 81a and the small pore 81b will be described. The large pore 81a has a diameter larger than the reference value when a value obtained by multiplying the diameter of the largest pore among the plurality of pores formed in the aluminum oxide film 81 by 0.5 is used as a reference value. It is a pore. Further, the small pore 81b is a pore having a diameter equal to or smaller than the reference value described above.

  Here, in the lattice hole pattern shown in FIG. 82, the pore interval T3 and the cycle L3 are set to the coordinate point C8 (pore interval: 0.14, cycle: 0.35) of the third embodiment shown in FIG. When set, as shown in FIG. 83, the phase difference may be within an allowable range (90 ° ± 10 °) in all wavelength regions of red (660 nm), infrared (790 nm), and blue (405 nm). found. Further, when the pore interval T3 and the cycle L3 are set to the coordinate point C9 (pore interval: 0.15, cycle: 0.35) in FIG. 45, as shown in FIG. 84, red (660 nm) and infrared In the wavelength region of (790 nm), the phase difference is within the allowable range (90 ° ± 10 °), while in the blue wavelength region (405 nm), the phase difference is outside the allowable range (90 ° ± 10 °). Turned out to be. That is, it was the same as the simulation result at the coordinate point C8 and the coordinate point C9 of the lattice hole pattern of the third embodiment.

  From this result, when the aluminum oxide film 81 having the grating hole pattern shown in FIG. 82 is used for the wave plate, if the grating interval T3 and the period L3 are defined as described above, a plurality of lights having different wavelengths are detected. It can be said that the range of the lattice interval T3 and the period L3 of the lattice hole pattern made of the aluminum oxide film 81 capable of obtaining excellent phase conversion characteristics is the same range as in the third embodiment shown in FIG. . That is, when the diameter S32 of the small pore 81b is equal to or smaller than the reference value, it can be said that the influence of the small pore 81b on the phase conversion characteristics is small. Therefore, when the grating hole pattern having the grating interval T3 and the period L3 shown in FIG. 82 is applied to the quarter-wave plate, two orthogonal light beams of red, infrared, and blue wavelengths can be obtained. The range in which the phase difference of the polarization component can be in the vicinity of 90 ° (within the range of 90 ° ± 10 °) is the following equation (9) to (11) in the third embodiment: 14) to Expression (16).

L3 ≦ 0.4 (14)
L3 ≧ −440.16T3 ³ + 63.334T3 ² −3.4273T3 + 0.3439 (15)
L3 ≧ 0.35 (T3-0.0825) ^0.434 +0.245 (16)
The range in which the phase difference between two polarization components orthogonal to each other at least in the red and infrared wavelength regions can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °) is as described above. It can be defined by the following equations (17) and (18) similar to the equations (12) and (13) of the third embodiment.

L3 ≦ 0.65 (17)
L3 ≧ −1.2018T3 ³ + 0.3022T3 ² + 1.29888T3 + 0.01 (18)
Thereby, when the aluminum oxide film 81 having the lattice hole pattern shown in FIG. 82 is used for the quarter wavelength plate, the lattice interval T3 and the period L3 are defined by the above formulas (14) to (16). (The same range as the range F3 in FIG. 45), the phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared, and blue is close to 90 ° ( (Within a range of 90 ° ± 10 °). Further, if the lattice interval T3 and the period L3 are set within the range defined by the above formulas (17) and (18) (the same range as the range F4 in FIG. 45), at least red and infrared wavelengths can be obtained. With respect to light, the phase difference between two polarization components orthogonal to each other can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °). Further, when the aluminum oxide film 81 having the lattice hole pattern shown in FIG. 82 is used for a half-wave plate, the phase difference is 180 ° ± with respect to light of all wavelengths of red, infrared, and blue. The range of the lattice interval T3 and the period L3 that can be within the range of 20 ° is a range defined by the above-described formulas (14) to (16) (the same range as the range F3 in FIG. 45). . Further, the ranges of the grating interval T3 and the period L3 that can make the phase difference within a range of 180 ° ± 20 ° with respect to light of at least red and infrared wavelengths are the above-described equations (17) and ( 18) (the same range as the range F4 in FIG. 45).

  Here, in the fifth embodiment, the lattice interval T3 and the period L3 of the lattice hole pattern of the aluminum oxide film 81 shown in FIG. 82 are within the ranges defined by the above-described equations (14) to (16) (FIG. 45). It is set to a value within the same range) as the middle range F3. That is, in the fifth embodiment, when the aluminum oxide film 81 having a lattice hole pattern is used for a quarter-wave plate, the phase difference is within an allowable range (90 ° in all red, infrared, and blue wavelength regions). Within ± 10 °). When the aluminum oxide film 81 having a lattice hole pattern is used for a half-wave plate, the phase difference is within an allowable range (180 ° ± 20 °) in all the red, infrared, and blue wavelength regions. become.

  The remaining configuration of the fifth embodiment is the same as that of the third or fourth embodiment.

  In the fifth embodiment, as described above, the pore interval T3 and the period L3 of the lattice hole pattern of the aluminum oxide film 81 constituting the wave plate are within the ranges defined by the equations (14) to (16) (FIG. In the case where the aluminum oxide film 81 is used for a quarter-wave plate, it is possible to reduce the red, infrared, and blue wavelengths with respect to each other. The phase difference between two orthogonal polarization components can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °). When the aluminum oxide film 81 is used for a half-wave plate, the phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared, and blue is about 180 ° (180 ° Within a range of ± 20 °. As a result, as in the third and fourth embodiments, a quarter-wave plate and a half-wave plate having good phase conversion characteristics can be obtained in a wide wavelength region.

  In the fifth embodiment, the diameter S32 of the small pore 81b is equal to or smaller than a reference value that is a value obtained by multiplying the diameter of the largest pore among the plurality of pores formed in the aluminum oxide film 81 by 0.5. As a result, the influence of the small pores 81b on the phase conversion characteristics is reduced. Thereby, in the aluminum oxide film 81 having a plurality of pores including the large pores 81a and the small pores 81b, by adjusting the period L3 of the lattice hole pattern composed of the plurality of large pores 81a, A wave plate having good phase conversion characteristics can be obtained.

  85 to 87 are a cross-sectional view and a plan view for explaining the manufacturing process of the wave plate according to the fifth embodiment shown in FIG. Next, with reference to FIGS. 82 and 85 to 87, a manufacturing process of the wave plate according to the fifth embodiment will be described.

First, as shown in FIG. 85, the transparent conductive film 2 made of ITO or ZnO and the aluminum film 80 are sequentially formed on the glass substrate 1 by using the same process as in the first reference embodiment shown in FIG. A texturing process is performed on the aluminum film 80 using a pressing member 84 made of a hard material such as SiC. The pressing member 84 has a plurality of conical convex portions 84a and 84b. A plurality of convex portions including the convex portions 84a and the convex portions 84b are arranged in a triangular lattice shape. Moreover, the root part of the convex part 84a has a larger diameter than the root part of the convex part 84b. Further, the large convex portion 84 a is disposed in a region corresponding to the pore row 82 (see FIG. 82) of the aluminum oxide film 81 of the pressing member 84, and the small convex portion 84 b is the pore row of the pressing member 84. It is arranged in a region other than the region corresponding to 82.

  As a result, as shown in FIGS. 86 and 87, on the surface of the aluminum film 80, one recess row 80c composed of a plurality of recesses 80a having a large diameter and one recess composed of a plurality of recesses 80b having a small diameter are provided. The recess rows 80d are alternately formed in the direction (X direction) orthogonal to the direction in which the optical axis extends (Y direction) with a distance B between the center lines. The plurality of recesses 80a constituting the recess row 80c are arranged in a row along the Y direction with a distance A between the centers, and the plurality of recesses 80b constituting the recess row 80d have a center distance A. They are arranged in a row along the Y direction with a gap therebetween. Further, the recesses 80a and 80b are arranged in a triangular lattice shape.

Thereafter, the aluminum film 80 in which the plurality of recesses 80a and 80b are formed is anodized using a process similar to that of the first reference embodiment shown in FIG. As a result, as shown in FIG. 82, a plurality of large pores 81a and a plurality of small pores 81b are included, and one pore row 82 composed of large pores 81a and one composed of small pores 81b. An aluminum oxide film 81 having a lattice hole pattern in which the pore rows 83 are alternately arranged at a predetermined interval is formed.

  In the manufacturing process of the fifth embodiment, as described above, the recesses 80a and 80b corresponding to the large pores 81a and the small pores 81b are formed in a triangular lattice shape, thereby forming the recesses 80a and 80b. By anodizing the aluminum film 80, pores 81a and 81b arranged in a triangular lattice pattern can be formed on the entire surface of the aluminum oxide film 81. In this case, the distance A between the centers of the recesses 80a (80b) adjacent to the direction in which the optical axis extends (Y direction) and the center line of the recesses 80a and 80b adjacent to the direction orthogonal to the direction in which the optical axis extends (X direction). Since the distance B is substantially equal, the distance A between the centers of the recesses 80a (80b) adjacent in the Y direction and the distance B between the center lines of the recesses 80a and 80b adjacent in the X direction are matched. An anodic oxidation voltage can be set. As a result, the large pores 81 a constituting the lattice hole pattern formed in the aluminum oxide film 81 can be prevented from branching inside the aluminum oxide film 81.

(Sixth embodiment)
FIG. 88 is a plan view showing a grating hole pattern of the wave plate according to the sixth embodiment of the present invention. Referring to FIG. 88, in the sixth embodiment, unlike the fifth embodiment, two pore rows composed of a plurality of small pores are arranged between pore rows composed of a plurality of large pores. The case will be described.

  In the sixth embodiment, as shown in FIG. 88, the aluminum oxide film 91 constituting the wave plate has a plurality of large pores 91a having a diameter S41 and a diameter S42 smaller than the diameter S41 of the pores 91a. A plurality of small pores 91b are formed. A plurality of pores including the large pores 91a and the small pores 91b are arranged in a triangular lattice shape. The aluminum oxide film 91 is an example of the “metal oxide film” in the present invention. The pores 91a and 91b are examples of the “first hole” and the “second hole” in the present invention, respectively.

  Here, in the sixth embodiment, a plurality of large pores 91a formed in the aluminum oxide film 91 constitute a lattice hole pattern for phase conversion of incident light. The plurality of large pores 91a constituting the lattice hole pattern are arranged along the arrow Y direction at a predetermined interval so as not to be connected to the pores 91a adjacent to the arrow Y direction (the direction in which the optical axis extends). The pore rows 92 are arranged in a shape. A plurality of the pore rows 92 are arranged at predetermined intervals in the arrow X direction so as not to be connected to the pore rows 92 adjacent in the arrow X direction orthogonal to the arrow Y direction. In addition, between the pore rows 92 adjacent in the arrow X direction, two pore rows 93 including a plurality of small pores 91b are arranged. That is, one pore row 92 and two pore rows 93 are alternately arranged at a predetermined interval in the arrow X direction. The pore row 92 is an example of the “hole row” in the present invention.

  Next, the definition of the pore interval T4 and the period L4 of the lattice hole pattern of the aluminum oxide film 91 constituting the wave plate according to the sixth embodiment will be described. The pore interval T4 is the distance between the centers of the large pores 91a adjacent in the arrow Y direction. The period L4 is the distance between the center lines of the pore arrays 92 adjacent in the arrow X direction. That is, when defining the pore interval T4 and the period L4, attention is paid only to the large pore 91a without considering the small pore 91b.

  Next, the definition of the large pore 91a and the small pore 91b will be described. The large pore 91a has a diameter larger than the reference value when a value obtained by multiplying the diameter of the largest pore among the plurality of pores formed in the aluminum oxide film 91 by 0.5 is used as the reference value. It is a pore. The small pore 91b is a pore having a diameter equal to or smaller than the above-described reference value.

  As in the fifth embodiment, when the diameter S42 of the small pore 91b is equal to or smaller than the reference value, it is considered that the influence of the small pore 91b on the phase conversion characteristics is small. For this reason, when the aluminum oxide film 91 having the lattice hole pattern shown in FIG. 88 is used for the wave plate, if the lattice interval T4 and the period L4 are defined as described above, a plurality of lights having different wavelengths can be obtained. It is considered that the range of the lattice interval T4 and the period L4 of the lattice hole pattern made of the aluminum oxide film 91 capable of obtaining good phase conversion characteristics is the same range as in the third embodiment shown in FIG. . Therefore, when the grating hole pattern having the grating interval T4 and the period L4 shown in FIG. 88 is applied to the quarter-wave plate, two light beams having wavelengths of red, infrared, and blue are orthogonal to each other. The range in which the phase difference of the polarization component can be in the vicinity of 90 ° (within the range of 90 ° ± 10 °) is the following equation (9) to (11) in the third embodiment: 19) to formula (21).

L4 ≦ 0.4 (19)
L4 ≧ −440.16T4 ³ + 63.334T4 ² −3.4273T4 + 0.3439 (20)
L4 ≧ 0.35 (T4-0.0825) ^0.434 +0.245 (21)
The range in which the phase difference between two polarization components orthogonal to each other at least in the red and infrared wavelength regions can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °) is as described above. It can be defined by the following equations (22) and (23) similar to the equations (12) and (13) of the third embodiment.

L4 ≦ 0.65 (22)
L4 ≧ −1.2018T4 ³ + 0.3022T4 ² + 1.29888T4 + 0.01 (23)
As a result, when the aluminum oxide film 91 having the lattice hole pattern shown in FIG. 88 is used for the quarter-wave plate, the lattice interval T4 and the period L4 are defined by the above formulas (19) to (21). (The same range as the range F3 in FIG. 45), the phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared, and blue is close to 90 ° ( (Within a range of 90 ° ± 10 °). Further, if the lattice interval T4 and the period L4 are set within the range defined by the above formulas (22) and (23) (the same range as the range F4 in FIG. 45), at least the wavelengths of red and infrared wavelengths With respect to light, the phase difference between two polarization components orthogonal to each other can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °). Further, when the aluminum oxide film 91 having the lattice hole pattern shown in FIG. 88 is used for a half-wave plate, the phase difference is 180 ° ± with respect to light of all wavelengths of red, infrared, and blue. The range of the lattice interval T4 and the period L4 that can be within the range of 20 ° is a range defined by the above-described formulas (19) to (21) (the same range as the range F3 in FIG. 45). . In addition, the range of the grating interval T4 and the period L4 that can make the phase difference within a range of 180 ° ± 20 ° with respect to light of at least red and infrared wavelengths is the above-described formula (22) and formula ( 23) (the same range as the range F4 in FIG. 45).

  Here, in the sixth embodiment, the lattice interval T4 and the period L4 of the lattice hole pattern of the aluminum oxide film 91 shown in FIG. 88 are within the ranges defined by the above-described equations (19) to (21) (FIG. 45). It is set to a value within the same range) as the middle range F3. That is, in the sixth embodiment, when the aluminum oxide film 91 having the lattice hole pattern is used for the quarter wavelength plate, the phase difference is within an allowable range (90 ° in all wavelength regions of red, infrared, and blue). Within ± 10 °). Further, when the aluminum oxide film 91 having a lattice hole pattern is used for a half-wave plate, the phase difference is within an allowable range (180 ° ± 20 °) in all the red, infrared, and blue wavelength regions. become.

  In addition, the other structure of 6th Embodiment is the same as that of the said 3rd or 4th Embodiment.

  In the sixth embodiment, as described above, the pore interval T4 and the period L4 of the lattice hole pattern of the aluminum oxide film 91 constituting the wave plate are within the ranges defined by the equations (19) to (21) (FIG. In the case where the aluminum oxide film 91 is used for a quarter-wave plate, the light in all wavelengths of red, infrared and blue can be compared with each other. The phase difference between two orthogonal polarization components can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °). Further, when the aluminum oxide film 91 is used for a half-wave plate, the phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared, and blue is about 180 ° (180 ° Within a range of ± 20 °. As a result, like the fifth embodiment, a quarter-wave plate and a half-wave plate having good phase conversion characteristics can be obtained in a wide wavelength region.

  In the sixth embodiment, the diameter S42 of the small pore 91b is equal to or less than a reference value that is a value obtained by multiplying the diameter of the largest pore among the plurality of pores formed in the aluminum oxide film 91 by 0.5. As a result, the influence of the small pores 91b on the phase conversion characteristics is reduced. Thereby, in the aluminum oxide film 91 having a plurality of pores including the large pore 91a and the small pore 91b, by adjusting the period L4 of the lattice hole pattern composed of the plurality of large pores 91a, A wave plate having good phase conversion characteristics can be obtained.

  Next, with reference to FIG. 88, the manufacturing process of the wave plate according to the sixth embodiment will be explained.

  First, using a process similar to that of the fifth embodiment shown in FIGS. 85 to 87, a plurality of recesses (not shown) arranged in a triangular lattice shape are formed on the surface of an aluminum film (not shown). To do. However, in the sixth embodiment, large convex portions (not shown) are arranged in regions corresponding to the pore rows 92 of the aluminum oxide film 91, and small convex portions (not shown) are pore rows. A pressing member (not shown) arranged in a region other than the region corresponding to 92 is used. That is, on the surface of the aluminum film, one recess row (not shown) consisting of a plurality of recesses having a large diameter and two recess rows (not shown) consisting of a plurality of recesses having a small diameter are optical axes. Are alternately formed in a direction perpendicular to the extending direction of the.

Thereafter, an aluminum film having a plurality of recesses is anodized using a process similar to that of the first reference embodiment shown in FIG. As a result, as shown in FIG. 88, a plurality of large pores 91a and a plurality of small pores 91b are included, and one pore row 92 composed of large pores 91a and two pores composed of small pores 91b. An aluminum oxide film 91 having a lattice hole pattern in which the pore rows 93 are alternately arranged at a predetermined interval is formed.

  In the manufacturing process of the sixth embodiment, as described above, the recesses corresponding to the large pores 91a and the small pores 91b are formed in a triangular lattice shape, and thereby the anodized aluminum film is anodized. As a result, the pores 91a and 91b arranged in a triangular lattice pattern can be formed on the entire surface of the aluminum oxide film. In this case, the distance between the centers of the recesses adjacent to the direction in which the optical axis extends (Y direction) is substantially equal to the distance between the center lines of the recesses adjacent to the direction orthogonal to the direction in which the optical axis extends (X direction). The anodization voltage can be set so as to match both the distance between the centers of the recesses adjacent in the Y direction and the distance between the center lines of the recesses adjacent in the X direction. Thereby, it is possible to prevent the large pores 91 a constituting the lattice hole pattern formed in the aluminum oxide film 91 from branching inside the aluminum oxide film 91.

(Seventh embodiment)
FIG. 89 is a plan view showing a grating groove pattern of the wave plate according to the seventh embodiment of the present invention. Referring to FIG. 89, unlike the first and second reference embodiments, the seventh embodiment includes a plurality of large pores and a plurality of small pores, and a pore composed of a plurality of large pores. A wave plate including an aluminum oxide film having a linear lattice groove pattern in which a plurality of pore groups including a plurality of rows are arranged at predetermined intervals will be described.

  In the seventh embodiment, as shown in FIG. 89, the aluminum oxide film 101 constituting the wave plate has a plurality of large pores 101a having a diameter S51 and a diameter S52 smaller than the diameter S51 of the pores 101a. A plurality of small pores 101b are formed. A plurality of pores including the large pores 101a and the small pores 101b are arranged in a triangular lattice shape. The aluminum oxide film 101 is an example of the “metal oxide film” in the present invention. The pores 101a and 101b are examples of the “first hole” and the “second hole” in the present invention, respectively.

  Here, in the seventh embodiment, a plurality of large pores 101a formed in the aluminum oxide film 101 constitute a linear lattice groove pattern for phase-converting incident light. In this linear lattice groove pattern, the pore group 103 including two pore arrays 102 composed of a plurality of large pores 101a is predetermined in the arrow X direction orthogonal to the arrow Y direction (the direction in which the optical axis extends). A plurality of structures are arranged at intervals. The two pore arrays 102 constituting the pore group 103 are arranged at a predetermined interval in the arrow X direction so as not to be connected to the adjacent pore arrays 102 in the arrow X direction. The plurality of pores 101a in the pore row 102 are arranged at a predetermined interval in the arrow Y direction so as not to be connected to the pores 101a adjacent in the arrow Y direction. In the seventh embodiment, the pore group 103 composed of a plurality of pores 101a not connected to each other is regarded as a groove portion of a linear lattice groove pattern. The plurality of small pores 101b are arranged in a triangular lattice pattern between the pore groups 103 adjacent in the arrow X direction. The pore row 102 is an example of the “hole row” in the present invention, and the pore group 103 is an example of the “hole group” in the present invention.

  Next, the definition of the effective groove width We5 and the period L5 of the linear lattice groove pattern of the aluminum oxide film 101 constituting the wave plate according to the seventh embodiment will be described. The effective groove width We5 is an average value of distances between a line in contact with the outermost end on one side of the pore group 103 and a line in contact with the outermost end on the other side. The period L5 is an average value of distances between lines in contact with the outermost ends on one side of the adjacent pore groups 103. That is, when the effective groove width We5 and the period L5 are defined, the small pore 101b is not considered, and only the pore group 103 including the large pore 101a is focused. In this case, the effective duty ratio De of the linear lattice groove pattern is De = (L5−We5) / L5.

  Next, the definition of the large pore 101a and the small pore 101b will be described. The large pore 101a has a diameter larger than the reference value when a value obtained by multiplying the diameter of the largest pore among the plurality of pores formed in the aluminum oxide film 101 by 0.5 is used as a reference value. It is a pore. The small pore 101b is a pore having a diameter equal to or smaller than the above reference value.

As in the fifth embodiment, when the diameter S52 of the small pore 101b is equal to or smaller than the reference value, it is considered that the influence of the small pore 101b on the phase conversion characteristics is small. Here, in 7th Embodiment, the area of the small pore 101b is set to 1/4 or less of the area of the large pore 101a. For this reason, it can be said that the influence which the small pore 101b has on a phase conversion characteristic is very small. In the seventh embodiment, the period L5 of the linear lattice groove pattern composed of a plurality of large pores 101a is set so as to approach the wavelengths of blue, infrared, and red light. For this reason, it can be said that the influence which the linear grating | lattice groove pattern which consists of several large pores 101a has on a phase conversion characteristic is larger than the influence which the small pore 101b has on a phase conversion characteristic. Thereby, when the aluminum oxide film 101 having the linear lattice groove pattern shown in FIG. 89 is used for the wave plate, the effective duty ratio De (= (L5−We5) / L5) and the period L5 as described above. Is defined, the effective duty ratio De and the range of the period L5 of the linear grating groove pattern made of the aluminum oxide film 101 capable of obtaining good phase conversion characteristics for a plurality of lights having different wavelengths are as follows: It is considered that the same range as that of the first reference embodiment shown in FIG.

Therefore, when the grating hole pattern having the effective duty ratio De (= (L5−We5) / L5) and the period L5 shown in FIG. 89 is applied to the quarter-wave plate, all of red, infrared, and blue The range in which the phase difference between two polarization components orthogonal to each other with respect to the wavelength can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °) is expressed by equation (1) in the first reference embodiment. -It can prescribe | regulate with the following formula | equation (24)-Formula (27) similar to Formula (4).

De ≧ 0.73 (24)
L5 ≦ 0.4 (25)
L5 ≧ 30.952 De ³ −74.751 De ² + 59.62De−15.328 (26)
L5 ≦ 3.0776De ² −5.1863De + 2.5772 (27)
The range in which the phase difference between two polarization components orthogonal to each other at least in the red and infrared wavelength regions can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °) is as described above. It can prescribe | regulate with the following formula | equation (28)-Formula (31) similar to Formula (5)-Formula (8) of 1st reference form.

L5 ≦ 0.65 (28)
L5 ≧ 2 × 10 ⁻¹⁴ e ^{31.263 De} (29)
L5 ≦ 6.0317De ² -10.352De + 5.0516 (30)
(De−0.85) ² /0.44 ² + (L5−0.41) ² /0.39 ² ≦ 1 (31)
As a result, when the aluminum oxide film 101 having the linear lattice groove pattern shown in FIG. 89 is used for the quarter-wave plate, the effective duty ratio De and the period L5 are expressed by the equations (24) to ( 27) (the same range as the range F1 in FIG. 2), the phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared and blue Can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °). Further, if the effective duty ratio De and the cycle L5 are set within the range defined by the above formulas (28) to (31) (the same range as the range F2 in FIG. 2), at least red and infrared It becomes possible to make the phase difference between two polarization components orthogonal to each other near 90 ° (within a range of 90 ° ± 10 °) with respect to light of a wavelength. In addition, when the aluminum oxide film 101 having the linear lattice groove pattern shown in FIG. 89 is used for a half-wave plate, the phase difference is set for light of all wavelengths of red, infrared, and blue. The range of the effective duty ratio De and the period L5 that can be within a range of 180 ° ± 20 ° is a range defined by the above-described formulas (24) to (27) (the range F1 in FIG. The same range). In addition, the effective duty ratio De and the range of the period L5 that can make the phase difference within a range of 180 ° ± 20 ° with respect to light of at least red and infrared wavelengths are represented by the above formulas (28) to (28) The range is defined by Expression (31) (the same range as the range F2 in FIG. 2).

  Here, in the seventh embodiment, the effective duty ratio De and the period L5 of the linear lattice groove pattern of the aluminum oxide film 101 shown in FIG. 89 are defined by the above equations (24) to (27). Is set to a value within the range (the same range as the range F1 in FIG. 2). That is, in the seventh embodiment, when the aluminum oxide film 101 having the linear lattice groove pattern is used for the quarter wavelength plate, the phase difference is within an allowable range in all the wavelength regions of red, infrared, and blue. (90 ° ± 10 °). Further, when the aluminum oxide film 101 having a linear lattice groove pattern is used for a half-wave plate, the phase difference is within an allowable range (180 ° ± 20 in all wavelength regions of red, infrared, and blue). °) within.

The remaining configuration of the seventh embodiment is the same as that of the first or second reference embodiment.

In the seventh embodiment, as described above, the effective duty ratio De (= (L5−We5) / L5) and the period L5 of the linear grating groove pattern of the aluminum oxide film 101 constituting the wave plate are expressed by the formula ( 24) to a value within the range defined by the formula (27) (the same range as the range F1 in FIG. 2), when the aluminum oxide film 101 is used for a quarter wavelength plate, red, red The phase difference between two polarization components orthogonal to each other can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °) for light of all wavelengths of outside and blue. Further, when the aluminum oxide film 101 is used for a half-wave plate, the phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared, and blue is about 180 ° (180 ° Within a range of ± 20 °. As a result, a quarter-wave plate and a half-wave plate having good phase conversion characteristics can be obtained in a wide wavelength region as in the first and second reference embodiments.

  In the seventh embodiment, the diameter S52 of the small pore 101b is equal to or smaller than a reference value that is a value obtained by multiplying the diameter of the largest pore among the plurality of pores formed in the aluminum oxide film 101 by 0.5. As a result, the influence of the small pores 101b on the phase conversion characteristics is reduced. Accordingly, in the aluminum oxide film 101 having a plurality of pores including the large pore 101a and the small pore 101b, the period L5 of the lattice hole pattern composed of the plurality of large pores 101a (one of the adjacent pore groups 103) By adjusting the distance between the lines in contact with the outermost end on the side, a wave plate having good phase conversion characteristics can be easily obtained.

  Next, with reference to FIG. 89, the manufacturing process of the wave plate according to the seventh embodiment will be explained.

  First, using a process similar to that of the fifth embodiment shown in FIGS. 85 to 87, a plurality of recesses (not shown) arranged in a triangular lattice shape are formed on the surface of an aluminum film (not shown). To do. However, in the seventh embodiment, large convex portions (not shown) are arranged in regions corresponding to the pore groups 103 of the aluminum oxide film 101, and small convex portions (not shown) are pore groups. A pressing member (not shown) arranged in an area other than the area corresponding to 103 is used. That is, a recess group (not shown) including two recess rows made of a plurality of recesses having a large diameter is formed on the surface of the aluminum film at a predetermined interval in a direction orthogonal to the direction in which the optical axis extends. . In addition, a plurality of recesses having a small diameter are formed in a triangular lattice shape between the recess groups adjacent to each other in the direction orthogonal to the direction in which the optical axis extends on the surface of the aluminum film.

Thereafter, an aluminum film having a plurality of recesses is anodized using a process similar to that of the first reference embodiment shown in FIG. As a result, as shown in FIG. 89, a pore group 103 including a plurality of large pores 101a and a plurality of small pores 101b, and including two pore arrays 102 composed of a plurality of large pores 101a. An aluminum oxide film 101 having a linear lattice groove pattern arranged at a predetermined interval is formed.

  In the manufacturing process of the seventh embodiment, as described above, the recesses corresponding to the large pores 101a and the small pores 101b are formed in a triangular lattice pattern, and the aluminum film in which the recesses are formed is anodized. As a result, the pores 101a and 101b arranged in a triangular lattice pattern can be formed on the entire surface of the aluminum oxide film 101. In this case, the distance between the centers of the recesses adjacent to the direction in which the optical axis extends (Y direction) is substantially equal to the distance between the center lines of the recesses adjacent to the direction orthogonal to the direction in which the optical axis extends (X direction). The anodization voltage can be set so as to match both the distance between the centers of the recesses adjacent in the Y direction and the distance between the center lines of the recesses adjacent in the X direction. As a result, the large pores 101 a constituting the linear lattice groove pattern formed in the aluminum oxide film 101 can be prevented from branching inside the aluminum oxide film 101.

  As a modification of the manufacturing process of the seventh embodiment described above, the following manufacturing process may be used. First, a plurality of concave portions having the same diameter are formed in a triangular lattice shape on the surface of the aluminum film, and then the aluminum film is anodized. Thereby, the aluminum oxide film 101 in which a plurality of small pores 101b having the same size are arranged in a triangular lattice shape is formed. Thereafter, a photoresist is formed on a region other than the region corresponding to the pore group 103 (see FIG. 89) of the aluminum oxide film 101. Then, using the photoresist as a mask, a region corresponding to the pore group 103 is formed by etching the aluminum oxide film 101 in which a plurality of pores 101b having the same size are arranged in a triangular lattice pattern with a phosphoric acid aqueous solution. Only the diameter of the small pores 101b located at is enlarged. As a result, as shown in FIG. 89, a pore group 103 including a plurality of large pores 101a and a plurality of small pores 101b, and including two pore arrays 102 composed of a plurality of large pores 101a. An aluminum oxide film 101 having a linear lattice groove pattern arranged at a predetermined interval is formed.

(Eighth embodiment)
FIG. 90 is a plan view showing a grating groove pattern of a wave plate according to an eighth embodiment of the present invention. Referring to FIG. 90, in the eighth embodiment, unlike in the seventh embodiment, a plurality of large pores of a pore group constituting a linear lattice groove pattern are adjacent to at least one large pore. The case where it is connected to will be described.

  In the eighth embodiment, as shown in FIG. 90, the aluminum oxide film 111 constituting the wave plate has a plurality of large pores 111a having a diameter S61 and a diameter S62 smaller than the diameter S61 of the pores 111a. A plurality of small pores 111b are formed. A plurality of pores including the large pores 111a and the small pores 111b are arranged over the entire surface. The aluminum oxide film 111 is an example of the “metal oxide film” in the present invention. The pores 111a and 111b are examples of the “first hole” and the “second hole” in the present invention, respectively.

  Here, in the eighth embodiment, a plurality of large pores 111 a formed in the aluminum oxide film 111 constitute a linear lattice groove pattern for phase-converting incident light. In this linear lattice groove pattern, the pore group 113 including a plurality of pore arrays 112 composed of a plurality of large pores 111a has a predetermined interval in the arrow X direction perpendicular to the arrow Y direction (the direction in which the optical axis extends). A plurality of structures are arranged with a gap therebetween. The plurality of large pores 111a of the pore row 112 constituting the pore group 113 are arranged so as to be connected to at least one of the adjacent large pores 111a. The plurality of small pores 111b are arranged so as not to be connected to each other between the pore groups 113 adjacent in the arrow X direction. The pore array 112 is an example of the “hole array” in the present invention, and the pore group 113 is an example of the “hole group” in the present invention.

  Next, the definition of the effective groove width We6 and the period L6 of the linear lattice groove pattern of the aluminum oxide film 111 constituting the wave plate according to the eighth embodiment will be described. The effective groove width We6 is an average value of distances between a line in contact with the outermost end on one side of the pore group 113 and a line in contact with the outermost end on the other side. The period L6 is an average value of distances between lines in contact with the outermost ends on one side of the adjacent pore groups 113. That is, when defining the effective groove width We6 and the period L6, attention is focused on only the large pore 111a without considering the small pore 111b. In this case, the effective duty ratio De of the linear lattice groove pattern is De = (L6−We6) / L6.

  Next, the definition of the large pore 111a and the small pore 111b will be described. The large pore 111a has a diameter larger than the reference value when a value obtained by multiplying the diameter of the largest pore among the plurality of pores formed in the aluminum oxide film 111 by 0.5 is used as the reference value. It is a pore. Further, the small pore 111b is a pore having a diameter equal to or smaller than the above-described reference value.

As in the fifth embodiment, when the diameter S62 of the small pore 111b is equal to or smaller than the reference value, it is considered that the influence of the small pore 111b on the phase conversion characteristics is small. Here, in the eighth embodiment, the area of the small pore 111b is set to ¼ or less of the area of the large pore 111a. For this reason, it can be said that the influence which the small pore 111b has on a phase conversion characteristic is very small. In the eighth embodiment, the period L6 of the linear lattice groove pattern composed of a plurality of large pores 111a is set so as to approach the wavelengths of blue, infrared, and red light. For this reason, it can be said that the influence which the linear grating | lattice groove pattern which consists of several large pores 111a has on a phase conversion characteristic is larger than the influence which the small pore 111b has on a phase conversion characteristic. Thereby, when the aluminum oxide film 111 having the linear lattice groove pattern shown in FIG. 90 is used for the wave plate, the effective duty ratio De (= (L6−We6) / L6) and the period L6 as described above. Is defined, the effective duty ratio De and the range of the period L6 of the linear grating groove pattern made of the aluminum oxide film 111 capable of obtaining good phase conversion characteristics for a plurality of lights having different wavelengths are: It is considered that the same range as that of the first reference embodiment shown in FIG.

Therefore, when the grating hole pattern having the effective duty ratio De (= (L6-We6) / L6) and the period L6 shown in FIG. 90 is applied to the quarter-wave plate, all of red, infrared, and blue The range in which the phase difference between two polarization components orthogonal to each other with respect to the wavelength can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °) is expressed by equation (1) in the first reference embodiment. -It can prescribe | regulate with the following formula | equation (32)-Formula (35) similar to Formula (4).

De ≧ 0.73 (32)
L6≤0.4 (33)
L6 ≧ 30.952 De ³ −74.751 De ² + 59.62De−15.328 (34)
L6 ≦ 3.0776De ² -5.1863De + 2.5772 (35)
The range in which the phase difference between two polarization components orthogonal to each other at least in the red and infrared wavelength regions can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °) is as described above. It can prescribe | regulate with the following formula | equation (36)-Formula (39) similar to Formula (5)-Formula (8) of 1st reference form.

L6 ≦ 0.65 (36)
L6 ≧ 2 × 10 ⁻¹⁴ e ^{31.263 De} (37)
L6 ≦ 6.0317De ² -10.352De + 5.0516 (38)
(De−0.85) ² /0.44 ² + (L6−0.41) ² /0.39 ² ≦ 1 (39)
Thereby, in the case where the aluminum oxide film 111 having the linear lattice groove pattern shown in FIG. 90 is used for the quarter-wave plate, the effective duty ratio De and the period L6 are expressed by the above equations (32) to ( 35) (the same range as the range F1 in FIG. 2), the phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared and blue Can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °). Further, if the effective duty ratio De and the period L6 are set within the range defined by the above formulas (36) to (39) (the same range as the range F2 in FIG. 2), at least red and infrared It becomes possible to make the phase difference between two polarized light components orthogonal to each other near 90 ° (within a range of 90 ° ± 10 °) with respect to light having a wavelength. In addition, when the aluminum oxide film 111 having the linear lattice groove pattern shown in FIG. 90 is used for a half-wave plate, a phase difference is set for light of all wavelengths of red, infrared, and blue. The range of the effective duty ratio De and the period L6 that can be within the range of 180 ° ± 20 ° is a range defined by the above-described formulas (32) to (35) (the range F1 in FIG. The same range). In addition, the effective duty ratio De and the range of the period L6 that can make the phase difference within the range of 180 ° ± 20 ° with respect to the light of at least red and infrared wavelengths are the above formulas (36) to (36) to The range is defined by the equation (39) (the same range as the range F2 in FIG. 2).

  Here, in the eighth embodiment, the effective duty ratio De and the period L6 of the linear lattice groove pattern of the aluminum oxide film 111 shown in FIG. 90 are defined by the above equations (32) to (35). Is set to a value within the range (the same range as the range F1 in FIG. 2). That is, in the eighth embodiment, when the aluminum oxide film 111 having a linear lattice groove pattern is used for a quarter wavelength plate, the phase difference is within an allowable range in all the wavelength regions of red, infrared, and blue. (90 ° ± 10 °). When the aluminum oxide film 111 having a linear lattice groove pattern is used for a half-wave plate, the phase difference is within an allowable range (180 ° ± 20 in all wavelength regions of red, infrared, and blue). °) within.

In addition, the other structure of 8th Embodiment is the same as that of the said 1st or 2nd reference form.

  In the eighth embodiment, as described above, the effective duty ratio De (= (L6−We6) / L6) and the period L6 of the linear lattice groove pattern of the aluminum oxide film 111 constituting the wave plate are expressed by the formula ( 32) to a value within the range defined by the formula (35) (the same range as the range F1 in FIG. 2), when the aluminum oxide film 111 is used for a quarter wavelength plate, red, red The phase difference between two polarization components orthogonal to each other can be in the vicinity of 90 ° (within a range of 90 ° ± 10 °) for light of all wavelengths of outside and blue. In addition, when the aluminum oxide film 111 is used for a half-wave plate, the phase difference between two polarization components orthogonal to each other for light of all wavelengths of red, infrared, and blue is about 180 ° (180 ° Within a range of ± 20 °. As a result, like the seventh embodiment, a quarter-wave plate and a half-wave plate having good phase conversion characteristics can be obtained in a wide wavelength region.

  In the eighth embodiment, the diameter S62 of the small pore 111b is equal to or less than a reference value that is a value obtained by multiplying the diameter of the largest pore among the plurality of pores formed in the aluminum oxide film 111 by 0.5. By doing so, the influence of the small pores 111b on the phase conversion characteristics is reduced. Thereby, in the aluminum oxide film 111 having a plurality of pores including the large pore 111a and the small pore 111b, the period L6 of the lattice hole pattern composed of the plurality of large pores 111a (one of the adjacent pore groups 113). By adjusting the average distance between the lines in contact with the outermost end on the side, a wave plate having good phase conversion characteristics can be easily obtained.

  Next, with reference to FIG. 90, the manufacturing process of the wave plate by 8th Embodiment is demonstrated.

  First, a plurality of recesses (not shown) are formed on the surface of an aluminum film (not shown) using a process similar to that of the fifth embodiment shown in FIGS. However, in the eighth embodiment, a plurality of convex portions are arranged over the entire surface, and large convex portions (not shown) are arranged in a region corresponding to the pore group 113 of the aluminum oxide film 111. In addition, a pressing member (not shown) in which a small convex portion (not shown) is arranged in a region other than the region corresponding to the pore group 113 is used. That is, a recess group (not shown) including a plurality of recess rows made of a plurality of recesses having a large diameter is formed on the surface of the aluminum film at a predetermined interval in a direction orthogonal to the direction in which the optical axis extends. . In addition, a plurality of recesses having a small diameter are formed between the recess groups adjacent to each other in the direction orthogonal to the direction in which the optical axis extends on the surface of the aluminum film.

Thereafter, an aluminum film having a plurality of recesses is anodized using a process similar to that of the first reference embodiment shown in FIG. As a result, as shown in FIG. 90, a pore group 113 including a plurality of large pores 111a and a plurality of small pores 111b and including a plurality of pore arrays 112 including a plurality of large pores 111a is predetermined. Thus, an aluminum oxide film 111 having a linear lattice groove pattern arranged at a plurality of intervals is formed.

  In the manufacturing process of the eighth embodiment, as described above, the recesses corresponding to the large pores 111a and the small pores 111b are formed over the entire surface, and the aluminum film in which the recesses are formed is anodized. Thereby, the pores 111a and 111b arranged over the entire surface of the aluminum oxide film 111 can be formed. In this case, the difference between the distance between the center lines of the recesses adjacent to the extending direction of the optical axis (Y direction) and the distance between the center lines of the recesses adjacent to the direction orthogonal to the extending direction of the optical axis (X direction) is reduced. Therefore, the anodic oxidation voltage can be set so as to match both the distance between the center lines of the recesses adjacent in the Y direction and the distance between the center lines of the recesses adjacent in the X direction. As a result, the large pores 111 a constituting the linear lattice groove pattern formed in the aluminum oxide film 111 can be prevented from branching inside the aluminum oxide film 111.

  As a modification of the manufacturing process of the eighth embodiment described above, the following manufacturing process may be used. First, an anodizing process is performed on an aluminum film having no recess formed on the surface. Thereby, the aluminum oxide film 111 in which a plurality of small pores 111b having the same size are randomly arranged is formed. Thereafter, a photoresist is formed on a region other than the region corresponding to the pore group 113 (see FIG. 90) of the aluminum oxide film 111. Then, by using the photoresist as a mask, the aluminum oxide film 111 in which a plurality of small pores 111b having the same size are randomly arranged is etched with a phosphoric acid aqueous solution, thereby being positioned in a region corresponding to the pore group 113. Only the diameter of the small pore 111b is enlarged. As a result, as shown in FIG. 90, a pore group 113 including a plurality of large pores 111a and a plurality of small pores 111b and including a plurality of pore arrays 112 including a plurality of large pores 111a is predetermined. Thus, an aluminum oxide film 111 having a linear lattice groove pattern arranged at a plurality of intervals is formed.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

For example, in the first and second reference embodiments, the effective duty ratio De and the period L1 of the linear lattice groove pattern of the aluminum oxide film are defined by the above four formulas (1) to (4). The values are set to values within the range F1 (for example, De: 0.88, L1: 0.38 (coordinate point P in FIG. 2)), but the present invention is not limited to this, and the above four equations You may make it set to the value within the range F2 prescribed | regulated by (5)-Formula (8). In this case, good phase conversion characteristics of the wave plate can be obtained at least in the red and infrared wavelength regions.

In the first and second reference embodiments, the example in which the wave plate of the present invention is applied to a CD-R / DVD compatible optical pickup device and a liquid crystal projector device as an optical device has been shown. Not limited to the CD-R / DVD compatible optical pickup device and the liquid crystal projector device, the present invention is also applicable to an optical device that requires a wave plate having good phase conversion characteristics in a wide wavelength region. Further, the wave plates of the third and fourth embodiments can be applied to an optical apparatus that requires a wave plate having good phase conversion characteristics in a wide wavelength region.

In the first to fourth reference embodiments and embodiments, the transparent conductive film is formed between the glass substrate and the aluminum oxide film. However, the present invention is not limited to this, and the glass substrate and the aluminum oxide are used. A transparent conductive film may not be formed between the film and the film.

In the first to fourth reference embodiments and embodiments described above, the lattice groove pattern or the lattice hole pattern is formed by using the anodic oxidation method, but the present invention is not limited to this, and the depth is large. If it is possible to form a lattice groove pattern and a lattice hole pattern having a uniform groove width and diameter in the depth direction, the lattice groove pattern and the lattice hole pattern are formed using a method other than the anodic oxidation method. May be.

In the first to fourth reference embodiments and embodiments described above, the lattice groove pattern or the lattice hole pattern is formed by anodizing the aluminum film. However, the present invention is not limited to this, and titanium and tantalum are used. A lattice groove pattern and a lattice hole pattern may be formed by anodizing other valve metals. However, in this case, it is necessary to newly define the effective duty ratio and period range of the grating groove pattern (wavelength plate) capable of maintaining a certain characteristic for a plurality of lights having different wavelengths. is there. In addition, it is necessary to newly define the gap interval and period range of the grating groove pattern and the grating hole pattern (wavelength plate) that can maintain a certain characteristic for a plurality of lights having different wavelengths.

In the above first to fourth reference embodiments and embodiments, an electrolytic solution made of phosphoric acid is used as an electrolytic solution used for anodization. However, the present invention is not limited to this, and is made of sulfuric acid, oxalic acid, or the like. An electrolytic solution may be used.

Moreover, in the said 1st-4th reference form and embodiment, although platinum was used as a cathode used for anodization, this invention is not restricted to this, You may use the cathode which consists of another material.

  Further, in the third and fourth embodiments, the pore interval T2 and the period L2 of the lattice hole pattern of the aluminum oxide film are within the range F3 defined by the above three formulas (9) to (11). Although the values are set to values (for example, T2: 0.10, L2: 0.35 (coordinate point Q in FIG. 45)), the present invention is not limited to this, and the two equations (12) and You may make it set to the value within the range F4 prescribed | regulated by Formula (13). In this case, good phase conversion characteristics of the wave plate can be obtained at least in the red and infrared wavelength regions.

  In the third and fourth embodiments, an aluminum oxide film having a lattice hole pattern composed of a plurality of pores arranged in a triangular lattice pattern is used as the aluminum oxide film constituting the wave plate. However, the present invention is not limited to this, and as shown in FIG. 91, the aluminum oxide film 120 may be formed so as to have a lattice hole pattern including a plurality of pores 120a arranged in a square lattice pattern. In addition, as shown in FIG. 92, the plurality of pores 121a arranged in the form of a square lattice have a lattice groove pattern in which the pores 121a adjacent in the arrow Y direction (the direction in which the optical axis extends) are connected. Alternatively, the aluminum oxide film 121 may be formed. However, if the aluminum film is oxidized using an anodic oxidation method, the pores arranged in a triangular lattice shape are easily formed in a self-organized manner, so a lattice made up of a plurality of pores arranged in a triangular lattice shape. It is preferable to use an aluminum oxide film having a hole pattern or a lattice groove pattern.

Moreover, in the said 5th-8th embodiment, by texturing using the pressing member which has several large convex parts and small convex parts, several large recessed parts and several small recessed parts on the surface of an aluminum film However, the present invention is not limited to this, and after forming a plurality of large concave portions on the surface of the aluminum film by texturing using a pressing member having only a plurality of large convex portions, the aluminum film A plurality of small recesses may be formed in a region other than the region where the large concave portion of the surface of the aluminum film is formed by roughening the region other than the region where the large concave portion of the surface is formed. If the aluminum film having the recesses is anodized in this way, large pores are formed in the region corresponding to the large recesses on the surface of the aluminum film, and the triangular lattice on the roughened surface of the aluminum film is formed. Small pores are formed in the region corresponding to the pattern. When the surface of the aluminum film is roughened, the surface of the aluminum film is about 100 W to about 500 W at a power of about 100 W using a RIE (Reactive Ion Etching) method using CF ₄ gas and H ₂ gas. Etching is preferably performed for 10 minutes. Also, the surface of the aluminum film can be roughened by annealing the surface of the aluminum film for about 30 minutes in an inert gas at a temperature of about 200 ° C. to about 600 ° C.

  Further, in the fifth and sixth embodiments, one or two pore rows made of a plurality of small pores are arranged between the pore rows made of the large pores constituting the lattice hole pattern. The invention is not limited to this, and three or more pore arrays composed of a plurality of small pores may be arranged between the pore arrays composed of large pores constituting the lattice pore pattern.

  In the seventh embodiment, the small pores are not arranged between the pore rows of the pore group composed of the large pores constituting the lattice groove pattern. However, the present invention is not limited to this, and the lattice grooves are not limited thereto. Small pores may be arranged between the pore rows of the pore group consisting of large pores constituting the pattern. The definition of the effective groove width and period of the grating groove pattern in this case is the same as the definition of the effective groove width We5 and period L5 of the grating groove pattern of the seventh embodiment. That is, the small pores arranged between the pore rows of the pore group consisting of the large pores constituting the lattice groove pattern are not considered.

  In the above embodiment, the “triangle” in the triangular lattice pattern means not only a regular triangle but also other triangles in a broad sense.

It is the perspective view which showed the structure of the quarter wavelength plate by the 1st reference form of this invention. It is the graph which showed the range of the effective duty ratio and period of the quarter wavelength plate which has a favorable phase conversion characteristic with respect to several light which has a different wavelength. It is an enlarged plan view of a lattice groove pattern for explaining the definition of an effective duty ratio. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A1 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A2 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A3 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A4 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A5 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and phase difference in coordinate point A6 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A7 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A8 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A9 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A10 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A11 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A12 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point A13 for prescribing the range shown in FIG. It is a simulation result which showed the relationship between the wavelength and phase difference in coordinate point A14 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point B1 for prescribing the range shown in FIG. It is a simulation result which showed the relationship between the wavelength and phase difference in coordinate point B2 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point B3 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point B4 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point B5 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point B6 for prescribing the range shown in FIG. 3 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point B7 for defining the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point B8 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point B9 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point B10 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point B11 for prescribing the range shown in FIG. 3 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point B12 for defining the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and the phase difference in coordinate point B13 for prescribing the range shown in FIG. It is a simulation result which showed the relationship between the wavelength and coordinate difference in coordinate point B14 for prescribing the range shown in FIG. It is the simulation result which showed the relationship between the wavelength in the coordinate point P, and a phase difference. It is sectional drawing for demonstrating an example of the manufacturing process of the quarter wavelength plate by the 1st reference form shown in FIG. It is sectional drawing for demonstrating an example of the manufacturing process of the quarter wavelength plate by the 1st reference form shown in FIG. It is a top view for demonstrating an example of the manufacturing process of the quarter wavelength plate by the 1st reference form shown in FIG. It is sectional drawing for demonstrating an example of the manufacturing process of the quarter wavelength plate by the 1st reference form shown in FIG. It is sectional drawing for demonstrating an example of the manufacturing process of the quarter wavelength plate by the 1st reference form shown in FIG. It is a top view for demonstrating an example of the manufacturing process of the quarter wavelength plate by the 1st reference form shown in FIG. It is a top view for demonstrating an example of the manufacturing process of the quarter wavelength plate by the 1st reference form shown in FIG. It is the schematic which showed the optical system of the CD-R / DVD compatible optical pick-up apparatus as an optical apparatus containing the quarter wavelength plate by the 1st reference form shown in FIG. It is the perspective view which showed the structure of the half-wave plate by the 2nd reference form of this invention. FIG. 42 is a schematic diagram showing an optical system of a liquid crystal projector device as an optical device including a half-wave plate according to the second reference embodiment shown in FIG. 41. FIG. 43 is a schematic diagram illustrating a configuration of a polarization conversion element of an optical system of the liquid crystal projector device illustrated in FIG. 42. It is the perspective view which showed the structure of the quarter wavelength plate by 3rd Embodiment of this invention. It is the graph which showed the range of the pore space | interval and period of the quarter wavelength plate which has a favorable phase conversion characteristic with respect to several light which has a different wavelength. It is an enlarged plan view of a lattice hole pattern for explaining the definition of pore interval and period. It is an enlarged plan view of the lattice groove pattern for explaining the definition of the pore interval and the period. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C1 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C2 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C3 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C4 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C5 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C6 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C7 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C8 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C9 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C10 for defining the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and the phase difference in the coordinate point C11 for prescribing the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C12 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C13 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C14 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C15 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point C16 for defining the range shown in FIG. It is the simulation result which showed the relationship between the wavelength and coordinate difference in the coordinate point D1 for prescribing the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D2 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D3 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D4 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D5 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D6 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D7 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D8 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D9 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D10 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D11 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D12 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D13 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D14 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D15 for defining the range shown in FIG. 46 is a simulation result showing a relationship between a wavelength and a phase difference at a coordinate point D16 for defining the range shown in FIG. It is the simulation result which showed the relationship between the wavelength in the coordinate point Q, and a phase difference. It is the perspective view which showed the structure of the half-wave plate by 4th Embodiment of this invention. It is the top view which showed the grating pattern of the waveplate by 5th Embodiment of this invention. It is the simulation result which showed the relationship between the wavelength and phase difference at the time of setting the lattice hole pattern of 5th Embodiment to the coordinate point C8 of FIG. It is a simulation result which showed the relationship between the wavelength and phase difference at the time of setting the lattice hole pattern of 5th Embodiment to the coordinate point C9 of FIG. FIG. 83 is a cross-sectional view for explaining a manufacturing process for the wave plate according to the fifth embodiment shown in FIG. 82; FIG. 83 is a plan view for explaining a manufacturing process for the wave plate according to the fifth embodiment shown in FIG. 82; FIG. 83 is a cross-sectional view for explaining a manufacturing process for the wave plate according to the fifth embodiment shown in FIG. 82; It is the top view which showed the grating | lattice hole pattern of the wavelength plate by 6th Embodiment of this invention. It is the top view which showed the grating | lattice groove pattern of the wavelength plate by 7th Embodiment of this invention. It is the top view which showed the grating | lattice groove pattern of the wave plate by 8th Embodiment of this invention. It is the top view which showed the grating hole pattern of the wave plate by the modification of 3rd and 4th embodiment. It is the top view which showed the grating groove pattern of the wave plate by the modification of 3rd and 4th embodiment. It is the perspective view which showed the concept of the wavelength plate which has the conventional linear grating | lattice groove pattern. FIG. 94 is a correlation diagram showing the relationship between the effective refractive index and the duty ratio of the conventional wave plate shown in FIG. 93. It is sectional drawing of the wave plate which has the grating | lattice groove pattern formed using the conventional photolithography technique and the etching technique. It is sectional drawing for demonstrating the manufacturing process of the triangular lattice pattern using the conventional anodic oxidation method. It is sectional drawing for demonstrating the manufacturing process of the triangular lattice pattern using the conventional anodic oxidation method. It is sectional drawing for demonstrating the manufacturing process of the triangular lattice pattern using the conventional anodic oxidation method. It is sectional drawing for demonstrating the manufacturing process of the triangular lattice pattern using the conventional anodic oxidation method. It is the top view which showed the two-dimensional photonic crystal formed using the conventional anodic oxidation method. It is the perspective view which showed the concept of the quarter wavelength plate which consists of quartz. It is the perspective view which showed the concept of the half-wave plate which consists of quartz. It is the simulation result which showed the relationship between the wavelength of the quarter wavelength plate which consists of quartz, and a phase difference.

1, 71 Glass substrate (substrate)
3, 43, 73, 81, 83, 91, 101, 111 Aluminum oxide film (metal oxide film)
21a Semiconductor laser device for CD-R (light source)
21b DVD semiconductor laser element (light source)
24 1/4 wave plate (wave plate)
51a Light source 61 1/2 wave plate (wave plate)
73a, 83a Pore (hole)
73b, 82, 83b, 92, 102, 112 Pore row (hole row)
81a, 91a, 101a, 111a Fine pore (first pore)
81b, 91b, 101b, 111b Fine pore (second pore)
103, 113 pore group (hole group)
F1, F3 range (second range)
F2, F4 range (first range)

Claims (19)

A substrate,
An aluminum oxide film formed on the substrate and having a linear lattice groove pattern;
A period L (μm) of the linear lattice groove pattern and a duty ratio De which is a ratio of a substantial width of the aluminum oxide film between adjacent lattice groove patterns to the period L (μm) are as follows: It is set to a value within a first range defined by four equations,
The aluminum oxide film has a plurality of holes,
When a value obtained by multiplying the diameter of the largest hole among the plurality of holes by 0.5 is used as a reference value, the plurality of holes include a first hole having a diameter larger than the reference value, and the reference value or less. And a second hole having a diameter of
The wavelength plate, wherein a period L (μm) of the grating groove pattern is a period of a grating groove pattern including the plurality of first holes .
L ≦ 0.65
L ≧ 2 × 10 ⁻¹⁴ e ^{31.263 De}
L ≦ 6.0317De ² -10.352De + 5.0516
(De−0.85) ² /0.44 ² + (L−0.41) ² /0.39 ² ≦ 1   2. The wave plate according to claim 1, wherein the period L (μm) and the duty ratio De within the first range are applied to light in at least red and infrared wavelength regions. The period L (μm) and the duty ratio De of the linear lattice groove pattern are further set to values within a second range defined by the following four formulas. Wave plate.
De ≧ 0.73
L ≦ 0.4
L ≧ 30.952 De ³ −74.751 De ² + 59.62De−15.328
L ≦ 3.0776De ² −5.1863De + 2.5772   4. The wave plate according to claim 3, wherein the period L (μm) and the duty ratio De within the second range are applied to light in all wavelength regions of red, infrared, and blue. The lattice groove pattern composed of the plurality of first holes is configured by arranging a plurality of hole groups including a plurality of hole arrays composed of the plurality of first holes at a predetermined interval,
The period of the grating groove patterns L ([mu] m) is the average value of the distance between lines tangent to the outermost ends of one side of the hole groups adjacent to each wavelength according to any one of claims 1 to 4 Board. A substrate,
An aluminum oxide film formed on the substrate and having either one of a linear lattice groove pattern in which a plurality of holes are connected and a lattice hole pattern in which the plurality of holes are arranged at a predetermined interval. Prepared,
The plurality of holes constituting any one of the lattice groove pattern and the lattice hole pattern included in the aluminum oxide film has a distance between centers of the hole interval T (μm) adjacent to the first direction. The hole rows are arranged in rows to form a hole row, and the hole row has a period L (which is an interval larger than the hole interval T (μm) in a second direction orthogonal to the first direction. are arranged in multiples,
The wavelength plate in which the period L (μm) and the hole interval T (μm) are set to values within a first range defined by the following two expressions.
L ≦ 0.65
L ≧ −1.2018T ³ + 0.3022T ² + 1.2988T + 0.01 The wave plate according to claim 6 , wherein the period L (μm) and the hole interval T (μm) within the first range are applied to light in at least red and infrared wavelength regions. The wavelength plate according to claim 6 or 7 , wherein the period L (μm) and the hole interval T (μm) are further set to values within a second range defined by the following three expressions. .
L ≦ 0.4
L ≧ −440.16T ³ + 63.334T ² −3.4273T + 0.3439
L ≧ 0.35 (T−0.0825) ^0.434 +0.245 The wavelength according to claim 8 , wherein the period L (μm) and the hole interval T (μm) in the second range are applied to light in all wavelength regions of red, infrared, and blue. Board. When a value obtained by multiplying the diameter of the largest hole among the plurality of holes by 0.5 is used as a reference value, the plurality of holes include a first hole having a diameter larger than the reference value, and the reference value or less. And a second hole having a diameter of
The period L (μm) of either the lattice groove pattern or the lattice hole pattern is the period of either the lattice groove pattern composed of the plurality of first holes or the lattice hole pattern composed of the plurality of first holes. The wave plate according to any one of claims 6 to 9 , wherein Either one of the lattice groove pattern made up of the plurality of first holes and the lattice hole pattern made up of the plurality of first holes has a hole group including a plurality of hole arrays made of the plurality of first holes separated by a predetermined interval. Are arranged by multiple,
The grating groove pattern and one of the period L of the grating pore patterns ([mu] m) is the average value of the distance between lines tangent to the outermost ends of one side of the hole groups adjacent, claim 10 Wave plate. A light source having a plurality of wavelength regions;
A predetermined phase difference is given to two orthogonally polarized components of light from the light source, and a substrate, a linear grating groove pattern formed on the substrate and having a birefringence characteristic, and a birefringence characteristic are provided. A wave plate including a metal oxide film having any one of the lattice hole pattern having ,
The metal oxide film is an aluminum oxide film having one of the linear lattice groove pattern in which a plurality of holes are connected and the lattice hole pattern in which the plurality of holes are arranged at a predetermined interval. Including
The plurality of holes constituting any one of the lattice groove pattern and the lattice hole pattern included in the aluminum oxide film has a distance between centers of the hole interval T (μm) adjacent to the first direction. The hole rows are arranged in rows to form a hole row, and the hole row has a period L (which is an interval larger than the hole interval T (μm) in a second direction orthogonal to the first direction. are arranged in multiples,
The period L (μm) and the hole interval T (μm) are set to values within a first range defined by the following two expressions .
L ≦ 0.65
L ≧ −1.2018T ³ + 0.3022T ² + 1.2988T + 0.01 The metal oxide film includes an aluminum oxide film having a linear lattice groove pattern,
A period L (μm) of the linear lattice groove pattern and a duty ratio De which is a ratio of a substantial width of the aluminum oxide film between adjacent lattice groove patterns to the period L (μm) are as follows: The optical device according to claim 12 , wherein the optical device is set to a value within a first range defined by the four equations:
L ≦ 0.65
L ≧ 2 × 10 ⁻¹⁴ e ^{31.263 De}
L ≦ 6.0317De ² -10.352De + 5.0516
(De−0.85) ² /0.44 ² + (L−0.41) ² /0.39 ² ≦ 1 The optical device according to claim 13 , wherein the wave plate having the period L (μm) and the duty ratio De within the first range is used for light in at least red and infrared wavelength regions. Period L ([mu] m) and the duty ratio De of the linear grating groove pattern further, is set to a value within a second range defined by the following four equations, according to claim 13 or 14 Optical device.
De ≧ 0.73
L ≦ 0.4
L ≧ 30.952 De ³ −74.751 De ² + 59.62De−15.328
L ≦ 3.0776De ² −5.1863De + 2.5772 Said second of said period in the range L ([mu] m) and the wavelength plate having the duty ratio De is red, is used for light in the infrared and all of the wavelength regions of blue, according to claim 15 Optical device. The wave plate having the period L (μm) and the hole interval T (μm) within the first range is used for light of at least red and infrared wavelength regions . The optical device according to any one of the above. The period L (μm) and the hole interval T (μm) are further set to values within a second range defined by the following three formulas: 18. An optical device according to 1.
L ≦ 0.4
L ≧ −440.16T ³ + 63.334T ² −3.4273T + 0.3439
L ≧ 0.35 (T−0.0825) ^0.434 +0.245 Said wavelength plate having the period L ([mu] m) and the hole spacing T in the second range ([mu] m) is red, is used for light in the infrared and all of the wavelength regions of blue, claim 18 An optical device according to 1.

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