JP4160682B2 - Microlens and microlens array - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a microlens having a single structure or an array structure including a refractive surface having an imaging function formed on a substrate and a light shielding portion having an opening corresponding to the refractive surface.
[0002]
[Prior art]
  In recent years, micromachining technology applying semiconductor process technology is rapidly progressing. By using this technology, a minute optical element that cannot be produced by conventional polishing or is extremely difficult and extremely expensive, and a minute optical element having an array structure in which many of them are arranged, It can be created at low cost with high accuracy and is applied in many fields.
[0003]
  One of the main examples of the application is a microlens array used for the purpose of improving the substantial aperture ratio of a liquid crystal display element for a projector. Normally, if no countermeasures are taken, about half of the light incident on the liquid crystal element is blocked by the drive wiring and the TFT part and does not contribute to the formation of the image, whereas it is wasted. By providing a minute convex lens for each pixel of the liquid crystal and condensing incident light on the liquid crystal opening, it is possible to avoid a decrease in the amount of transmitted light.
[0004]
  An example of such a liquid crystal element is described in, for example, Japanese Patent Laid-Open No. 9-258195. The lens used for the purpose of condensing is mainly a convex lens, and a method of forming a spherical surface by surface tension is used for forming the lens by heating and fluidizing a photoresist film patterned into a predetermined shape. ing.
[0005]
  When the photoresist is transparent, the lens shape may be used as it is, but in many cases, the lens is required to have heat resistance, so that the convex lens shape can be transferred to a substrate such as glass by dry etching. Done. In addition, by molding a substrate formed by such a method using a glass or an optical plastic as a matrix as a mother mold, elements having the same shape can be produced at low cost.
[0006]
  A method for manufacturing a microlens array based on heat fluidization of such a thermoplastic material is described in, for example, Japanese Patent Application Laid-Open No. 6-194502. By this method, it is possible to satisfactorily create a convex lens-shaped micro optical element array in general.
[0007]
  In recent years, a liquid crystal display used for a liquid crystal projector has a pixel pitch of about 20 μm, but it tends to be miniaturized in order to reduce the size of the device. It is expected to be refined to ˜7 μm.
[0008]
  According to the thermal deformation method described above, such a fine convex lens array can be formed. However, since the shape error of the refracting surface relatively increases as the lens diameter decreases, the condensing spot is expected. As a result, there is a problem that it cannot be squeezed as much as possible, that is, the resolution is lowered.
[0009]
  To this problem, E.I. H. Linfoot and E.W. According to Wo1f's academic paper "Proceedings of Physica 1 Society B, Vol. Pp. 145 to 149 (1953)" It is known that the resolving power is improved as compared with a circular opening. If this principle is used, it is considered that the resolving power of the microlens array can be improved. Such a structural example is also described in, for example, JP-A-8-313706.
[0010]
  The method for improving the resolving power by shielding the central portion in this way has the effect of increasing this in the resolving power, but the central portion of the microlens is blocked, so that the amount of transmitted light is significantly reduced. Is produced. Therefore, if this improvement method is applied to an element for the purpose of effective utilization of the transmitted light beam, such as the microlens in the above-described liquid crystal projector, the amount of transmitted light will eventually decrease, so that the original purpose of the element cannot be achieved. This creates a problem and this improvement method cannot be used in practice.
[0011]
  If the microlens has a relatively large diameter of about several tens of μm or more as before, the method of shielding the center of the lens as in the above-described conventional example also shows a certain effect. However, when the diameter becomes less than 10 μm, the demerit of a decrease in the amount of transmitted light becomes more dominant.
[0012]
[Problems to be solved by the invention]
  As described above, there is no good means for improving the resolving power for a high-definition microlens having a diameter of less than about 10 μm.
[0013]
  Therefore, an object of the present invention is to provide a microlens having a structure capable of improving the resolving power without causing a decrease in the amount of transmitted light even in a microlens having a diameter of less than 10 μm.
[0014]
  The present invention further clarifies an example of a more optimal specific structure that is excellent in productivity, light condensing property, etc. in realizing the above object.
[0015]
[Means for Solving the Problems]
  The invention described in claim 1BaseA spherical or aspherical refracting surface formed on at least one surface of the plate, and a light shielding portion having an opening corresponding to the size of the refracting surface.The diameter of the refracting surface is Ten less than μmIn the microlens, the position overlapping the refractive surface or the refractive surfaceThe outer peripheryInterfering with the diffracted light emitted from the refractive surfaceA phase shift unit for generating an optical phase difference so as to reduce the intensity of the diffracted light, and the opening of the light shielding unit is larger than the outer periphery of the refractive surface and has a shape similar to the outer peripheral shape of the refractive surface. The phase shift portion is formed of a substrate surface structure region in which a large number of columnar protrusions are formed in a substrate region having a constant width between the outer periphery of the refractive surface and the opening.
[0016]
  In this specification, the “light beam of wavelength λ” means a light beam having a relatively narrow wavelength range such as laser light, or a light beam having a relatively wide wavelength range such as light separated by a color separation prism. .
[0017]
  If the diffracted light overlaps the focused light from the refracting surface, the condensing spot becomes larger. The intensity of the diffracted light is reduced, the focused spot is not increased by the diffracted light, and the resolution as a lens is improved. Since there is no part that blocks the light transmitted through the refracting surface, only the intensity of the diffracted light from the refracting surface that causes the resolution to decrease is effectively utilized without reducing the amount of light by using the phase shift unit. Even in the case of a very fine structure having a diameter of less than 10 μm, the luminous flux can be condensed in a smaller area without causing a decrease in the amount of transmitted light.
  Further, since it is not necessary to deposit a thin film when forming the phase shift portion, it is possible to provide a highly versatile phase shift portion applicable to more cases even when there is no suitable thin film material. .
[0018]
  The invention according to claim 2 is the microlens according to claim 1,The columnar projections in the substrate surface structure region satisfy a range in which a ratio P: D2 of the diameter D2 of the inscribed circle of the projection portion to the arrangement pitch P of the projections is 1: 0.1 to 1: 0.5. Is formed.
[0019]
  Therefore,Claim 1In realizing the described invention,A phase shift part that provides better light-collecting characteristicsCan be provided.
[0020]
  A third aspect of the present invention is the microlens according to the first aspect.The columnar protrusion in the substrate surface structure region has a ratio D2 between the height H2 of the protrusion and the diameter D2 of the protrusion. : H2 is formed to satisfy the range of 1: 2 to 1:10.
[0021]
  Therefore, in realizing the invention of claim 1,A phase shift part that provides better light-collecting characteristicsCan be provided.
[0022]
  The invention described in claim 4Any one of claims 1 to 3In the described microlens,A transparent material having a refractive index different from that of the protruding portion is filled in the protruding gap portion in the substrate surface structure region.
[0023]
  Therefore,Claims 1 to 3In realizing the described invention, it is necessary to improve the environmental resistance.A phase shift unit can be provided.
[0024]
  The invention according to claim 5The microlens according to any one of claims 1 to 4. And a microlens having an array structure in which a plurality of the refractive surfaces, the openings, and the phase shift portions are arranged one-dimensionally or two-dimensionally.In the array.
[0025]
  Therefore, for example, even when an array structure that is applied to a liquid crystal projector or the like is provided, it is possible to obtain an effect that the light condensing property can be enhanced without a decrease in the amount of transmitted light.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
  A first embodiment of the present invention will be described with reference to FIG. This embodiment shows a basic configuration example of a microlens 1 corresponding to the invention described in claim 1.
[0027]
  The microlens 1 is schematically formed in a spherical shape so as to form a convex lens on one surface of a substrate 2 that transmits a light beam having a wavelength λ, for example, and corresponds to the refractive surface 3. And a light shielding part 5 having a circular opening 4 formed concentrically. The phase shift part 6 is added to a part of the substrate 2 as described above. This phase shift unit 6 is for controlling the phase of light transmitted through this portion so as to generate a preset optical phase difference. For example, the phase shift unit 6 partially overlaps with the refractive surface 3 in the region of the opening 4. In such an annular shape (doughnut shape), it is formed on the surface opposite to the refractive surface 3. That is, the light beam transmitted through the phase shift unit 6 interferes with the diffracted light emitted from the refractive surface 3.
[0028]
  In such a configuration, the light beam transmitted through the refracting surface 3 is collected, and at the same time, a part thereof is diffracted by the opening around the refracting surface 3 to become diffracted light. Here, in the conventional microlens, only a light-shielding portion having an opening substantially the same shape as the refractive surface is provided on the outer periphery of the refractive surface, and the opening of the refractive surface and the opening of the light-shielding portion are substantially the same shape. The diffracted light reaches the focal plane without being reduced, and the diffracted light overlaps with the focused light from the microlens, resulting in a larger focused spot.
[0029]
  In this respect, in the microlens 1 of the present embodiment, the opening 4 formed in the light-shielding portion 5 is similar to the outer peripheral shape (circular shape) of the refractive surface 3 and larger than the refractive surface 3, and the outer periphery of the refractive surface 3 Since the phase shift unit 6 is provided in the vicinity of the portion, the diffracted light generated in the opening around the refracting surface 3 is transmitted through the phase shift unit 6 and then overlaps with the diffracted light diffracted by the opening 4 of the light shielding unit 5. . Therefore, if the phase shift amount in the phase shift unit 6 is appropriately set, the energy is reduced by causing interference between the diffracted light generated at the opening of the refractive surface 3 and the diffracted light generated at the opening 4 of the light shielding unit 5. Can approach zero. Therefore, all the light beams incident on the refracting surface 3 of the microlens 1 contribute to focusing, and are condensed without increasing the condensing spot by the diffracted light. When the light beam has a certain wavelength width, the phase shift amount may be determined with respect to the center wavelength or the like.
[0030]
  According to the structure of the present embodiment, since there is no light-shielding portion in the refracting surface 3 portion as seen in the conventional resolution improving method using an annular opening, the refracting surface 3 of the microlens 1 is transmitted. Without reducing the amount of light to be transmitted, only the intensity of the diffracted light from the refracting surface 3 that causes the resolution to decrease is caused to interfere with the diffracted light from the refracting surface 3 with light beams having different phases transmitted through the phase shift unit 6. Therefore, it can be effectively reduced. Therefore, the resolving power of the microlens 1 can be improved without causing a reduction in the amount of light, and the light can be condensed in a smaller spot as compared with the conventional microlens.
[0031]
  This makes it possible to improve the light source light utilization efficiency even in a high-definition transmissive liquid crystal panel with a small pixel pitch, which has not been able to sufficiently enhance the light utilization efficiency with conventional microlens arrays. Brighter display brightness can be realized in a projector apparatus or the like.
[0032]
  The present inventionAs a reference exampleA second embodiment will be described with reference to FIGS. Parts that perform the same or equivalent functions as the parts shown in FIG.As a reference exampleThe same applies to each embodiment). In contrast to the first embodiment showing the basic configuration example, in the present embodiment, it is important to determine the specific structure of the above-described phase shift unit 6 and how to manufacture it. Considering this point, one example of a more specific configuration of the microlens 1 suitable for various cases and industrially easy to produce is shown based on many examinations and experiments.
[0033]
  That is, as a basic structure suitable for most cases, the phase shift unit 6 of the present embodiment has a transparent thin film having a preset optical thickness with respect to the light flux of wavelength λ. It is formed as a thin film region patterned so as to form an annular shape having a constant width along the vicinity of the outer periphery.
[0034]
  According to such a structure, the phase shift amount of the phase shift unit 6 can be arbitrarily set simply by changing the film thickness of the transparent thin film, and there is an advantage that its manufacture is easy.
[0035]
  Examples of the transparent thin film to be the phase shift portion 6 include silicon oxide, silicon nitride, silicon oxynitride (SiON), aluminum oxide, calcium fluoride, magnesium fluoride, zinc oxide, tantalum oxide formed by vacuum deposition or sputtering. Most transparent thin films such as zirconium oxide, zirconium nitride, and zirconium oxynitride can be used. Moreover, the thin film of the composition with which these compounds were mixed may be sufficient. Also, various optical glass sputtering films can be used. These thin films have established manufacturing processes and have high reproducibility of film thickness and refractive index. Therefore, the reproducibility of the phase shift amount with respect to the light flux is high, and the manufacture of the microlens 1 of the present embodiment is facilitated.
[0036]
  Here, when the use environment temperature of the microlens 1 is a relatively low temperature of 200 ° C. or less, the transparent thin film that becomes the phase shift unit 6 includes PMMA, polyimide, polyvinylidene fluoride, polytetrafluoroethylene, and the like. These resin thin films or other transparent resin thin films can also be used.
[0037]
  FIG. 2A shows a basic structure of an array-structured microlens having a phase shift portion 6 obtained by patterning these transparent thin films. The phase shift unit 6 may be formed on the same surface as the refracting surface 3 as shown in FIG. Further, a part thereof may overlap with the refracting surface 3 as shown in FIG. 2 (b), or may be formed adjacently as shown in FIG. 2 (c).
[0038]
  Further, the refractive surface 3 may be a concave surface as shown in FIG. The phase shift unit 6 may be formed on the same surface as the refracting surface 3 as shown in FIG. Further, a part thereof may overlap with the refracting surface 3 as shown in FIG. 3B, or may be formed adjacently as shown in FIG.
[0039]
  Further, the refracting surface 3 may be a refracting surface in which the concave surface 3a of the substrate 2 is filled with a transparent material 3b having a different refractive index as shown in FIG. The phase shift unit 6 may be formed on the same surface as the refractive surface 3 as shown in FIG. Further, a part thereof may overlap with the refracting surface 3 as shown in FIG. 4B, or may be formed adjacently as shown in FIG.
[0040]
  Further, a plurality of refracting surfaces 3 may be provided as shown in FIG. As shown in FIG. 5A, the phase shift unit 6 may be formed with the refractive surfaces 3 on the individual substrates 2a and 2b, respectively, and the phase shift unit 6 may be stacked on the respective surfaces, as shown in FIG. 5B. The two refracting surfaces 3 formed on both surfaces of the substrate 2 may be adjacent to each other or partially overlapped with each other. As shown in FIG. 5C, the phase shift portions 6 may be formed on both sides of the substrate 2. The plurality of refracting surfaces 3 may be partially refracting refracting surfaces or concave refracting surfaces filled with a transparent material.
[0041]
  Further, as shown in FIG. 6A, the phase shift unit 6 may be continuous between the adjacent microlenses 1 when forming the microlens having the array structure (microlens array 7).
[0042]
  When the distance between the microlenses 1 of the microlens array 7 is small, it is difficult to provide the light shielding portion 5. Only in such a case, an effect can be obtained to some extent by using only the phase shift unit 6 without providing the light shielding unit. Therefore, a structure without the light shielding unit as shown in FIG. 6B may be used.
[0043]
  Further, in order to enhance the effect, the phase shift unit 6 may have a thickness change in the plane as shown in FIG. 7A and change the phase amount depending on the position.
[0044]
  The present inventionAs a reference exampleA third embodiment will be described with reference to FIGS.The
[0045]
  First, considering the phase shift unit 6 according to the second embodiment described above, since it is necessary to pattern in a ring shape, a photomask in the manufacturing process is newly required, leading to an increase in manufacturing cost. Therefore, in the present embodiment, as a structure of the phase shift portion suitable for the case where it is desired to keep the manufacturing cost as low as possible, the opening 4 of the light shielding portion 5 is larger than the refracting surface 3 and has a similar shape to the phase shift portion 6. Is a thin film region in which a transparent thin film having a predetermined optical thickness with respect to light of wavelength λ is patterned on the refracting surface 3 in a shape similar to the refracting surface 3.
[0046]
  An example of this structure is shown in FIG. Since the region of the phase shift portion 6 delays the phase of the transmitted light of the refracting surface 3 with respect to the surrounding opening, the phase shift portion is provided on the outer peripheral portion of the refracting surface 3 by appropriately determining this phase amount. Equivalent effects can be obtained. The transparent thin film constituting the phase shift unit 6 can be the same as in the case of the second embodiment described above. According to this structure, the photomask used for patterning the shape of the phase shift portion 6 can also be used as the photomask used when the refractive surface 3 is formed.
[0047]
  Therefore, an effect close to that obtained when the phase shift unit 6 having the structure according to the second embodiment is used is obtained, and an advantage that an increase in manufacturing cost can be suppressed is obtained. However, since the phase shift portion 6 is provided on the refractive surface 3, it is very important that the transparent thin film has a high light transmittance. In addition, the uniformity of the film thickness on the refractive surface 3 is also strictly required. Such a condition can be realized in a normal thin film forming apparatus. However, depending on the wavelength used for the microlens 1 or the microlens array 7, a thin film material having excellent light transmittance cannot be obtained or is uniform. Film formation may be difficult. In such a case, the structure of the phase shift unit 6 according to the second embodiment in which no thin film is provided on the refracting surface 3 may have a low transmittance or poor uniformity of the transparent thin film. Since there is a feature that does not easily lead to characteristic deterioration, the microlens 1 or the microlens array 7 having higher light collecting performance tends to be realized. Accordingly, when the light condensing performance of the microlens 1 or the microlens array 7 is more important than the manufacturing cost, the phase shift unit 6 according to the second embodiment is suitable.
[0048]
  In the microlens array 7 using the phase shift unit 6 of the present embodiment, the refractive surface 3 may be a concave surface as shown in FIG.
[0049]
  The refracting surface 3 may be a refracting surface in which the concave surface 3a of the substrate 2 is filled with a transparent material 3b having a different refractive index as shown in FIG. Further, a plurality of refracting surfaces 3 may be provided as shown in FIG.
[0050]
  Further, as shown in FIG. 9A, the phase shift portion 6 may be formed on the opposite surface of the refracting surface 3. This structure is effective because the manufacturing is easy when the distance between the microlenses 1 is small in the microlens array 7. A structural example of the microlens array 7 in which the phase shift unit 6 is provided on the refracting surface 3 is shown in FIG.
[0051]
  Further, in order to enhance the effect, the phase shift unit 6 may provide a change in thickness within the plane as shown in FIG. 10 and change the phase amount depending on the position.
[0052]
  The present inventionAs a reference exampleA fourth embodiment will be described with reference to FIG.The in frontThe phase shift unit 6 according to the second and third embodiments described above is provided with a phase shift region in the vicinity of the periphery of the refracting surface. An annular light transmission region 8 is further provided around the periphery, and a phase shift portion 6 having a structure in which a transparent thin film is deposited is provided in the light transmission region 8.
[0053]
  This structure is shown in FIG. In this structure, the openings 4 corresponding to the phase shift portions 6 of the light shielding portion 5 are collectively formed by the same photomask as the openings corresponding to the refracting surface 3, so that the mutual positional relationship can be maintained extremely high. Easy. Therefore, there is an advantage that the position of the phase shift unit 6 is defined by the opening 4 of the light shielding unit 5, and the alignment accuracy when patterning the phase shift unit 6 is eased and the manufacture becomes easy. However, since extra space is required around the microlens 1, it is suitable for a single microlens 1 or a microlens array 7 having a wide interval, and in the case of a lens array that is desired to be created with the distance between lenses as narrow as possible. Not suitable.
[0054]
  The present inventionAs a reference exampleA fifth embodiment will be described. When a patterned thin film is used as the phase shift region, the usable material may be very limited depending on the wavelength of transmitted light, and it may be difficult to create in practice. As a structure suitable for such a case, in this embodiment, a structure of an unnecessary phase shift region of a thin film is examined.
[0055]
  One of the structures is that the substrate 2 is engraved by partially etching the substrate material with a resist mask, etc., and the thickness of the substrate 2 at the opening corresponding to the phase shift portion 6 is changed to delay the phase of transmitted light. And this region is the phase shift unit 6. ThisAccording to the structure, since it is not necessary to deposit a thin film constituting the phase shift unit 6, an effect of facilitating manufacture can be obtained.
[0056]
  However, this method can be performed only when the substrate material can be easily etched to a uniform depth and the refractive index of the substrate 2 is appropriate for the required phase delay amount. The scope of application is somewhat limited.
[0057]
  The present inventionAs a reference exampleA sixth embodiment will be described. Therefore, in this embodiment, as a structure applicable to more cases, a large number of small protrusions are formed on the substrate 2 to form a region having an apparent refractive index different from that of the substrate 2.
[0058]
  More specifically, as a result of creating various structures and comparing them by experiment, a surface structure region in which a large number of thin plate-like protrusions having a rectangular cross section were formed was formed as the phase shift portion 6.To structureAccording to the results, good results were obtained. Further, a structure in which a surface structure region in which a large number of columnar protrusions are formed is formed as a phase shift portion 6 (Claim 1Good results were also obtained by the equivalent of the described invention.
[0059]
  Comparing these two structures in the present embodiment, in terms of mechanical strength, the phase shift portion 6 based on the surface structure region in which the plate-like protrusions are formed is stronger, and the microlens array 7 having high environmental characteristics. It is suitable when you need it. In terms of the effect as a phase shift region, that is, in that the light spot condensed by the microlens 1 can be made smaller, the phase shift portion 6 by the surface structure region in which columnar protrusions are formed is superior and the light condensing performance. This is suitable when a microlens array 7 that emphasizes the above is required.
[0060]
  When the phase shift part 6 by the surface structure region in which the plate-like protrusions are formed is used, it is observed that the light collecting performance of the completed microlens array 7 is changed by the arrangement pitch P. The range of pitch P was examined. As a result, the above-mentioned plate-like protrusions have a pitch of arrangement that is λ / 3 or less with respect to the wavelength λ of transmitted light.TogetherIt was found that good light collecting performance can be obtained.
[0061]
  In addition, when using the phase shift portion 6 by the surface structure region in which the plate-like protrusions are formed, it was observed that the light condensing performance of the completed microlens array 7 changes depending on the thickness D of the protrusion portions. The optimum range of the thickness D of the protruding portion was examined by experiment. As a result, when the thickness D of the protruding portion is in the range of 1: 0.1 to 1: 0.5 in the ratio P: D of the protruding portion to the pitch P of the arrangement.TogetherIt was found that good light collecting performance can be obtained.
[0062]
  In addition, when using the phase shift portion 6 by the surface structure region in which the plate-like protrusions are formed, it was observed that the light condensing performance of the completed microlens array 7 changes depending on the height H of the protrusion portions. The optimum range of the height H of the protruding portion was examined by experiment. As a result, it was found that when the height H of the protruding portion is in the range of 1: 2 to 1:10 in the ratio D: H to the thickness D of the protruding portion, a good light collecting performance can be obtained.
[0063]
  The plate-like protrusions can be formed in parallel lines, in a ring concentric with the refracting surface 3, or radially around the refracting surface 3. Since the characteristics of these change depending on the polarization state of incident light, etc., it is desirable that they be optimally shaped by experiments in actual use conditions. When the phase shift portion 6 with the surface structure region in which the columnar protrusions are formed is used, it is observed that the condensing performance of the completed microlens array 7 is changed by the arrangement pitch P. The range of P was examined. As a result, the columnar protrusions are arranged so as to be at the intersections of the lattices, and the pitch of the arrangement is 1/3 or less of the wavelength λ of the transmitted light.TogetherIt was found that good light collecting performance can be obtained.
[0064]
  In the case of using the phase shift portion 6 by the surface structure region in which the columnar protrusion is formed, it is observed that the light condensing performance of the completed microlens array 7 changes depending on the thickness of the protrusion. The thickness range was examined. As a result, when the diameter D2 of the inscribed circle of the protrusion portion is in the range of 1: 0.1 to 1: 0.5 in the ratio P: D2 of the protrusion to the arrangement pitch P (Claim 2It has been found that a good light collecting performance can be obtained.
[0065]
  In the case of using the phase shift part 6 by the surface structure region in which the columnar protrusions are formed, it is observed that the light condensing performance of the completed microlens array substrate changes depending on the height H2 of the protrusions. The range of height H2 was examined. As a result, when the height H2 of the protruding portion is in the range of 1: 2 to 1:10 in the ratio D2: H2 with the diameter D2 of the protruding portion (Claim 3The light collecting performance was equivalent to that of the described invention.
[0066]
  When a transparent resin material having a refractive index different from that of the substrate material and having a low viscosity before being solidified and can be easily injected between the protrusions of the phase shift portion 6 is available, or when the refractive index is different from that of the substrate material Rate transparent thin film can be filled and deposited in good condition between the protrusions of the phase shift portion 6(Claim 4By these methods, the phase shift unit 6 can be mechanically strengthened, and the resistance of the completed microlens array 7 to vibration and surface friction can be increased. However, since this structure increases the manufacturing cost, it is not necessary to apply this structure when the microlens array 7 itself does not require high environmental resistance, such as when the microlens array 7 is sealed inside the module.
[0067]
  Even when a large number of plate-like or columnar protrusions are arranged to form the phase shift unit 6, the positional relationship between the refractive surface 3 and the phase shift unit 6 is that the transparent thin film is used as the phase shift unit as in the above-described embodiment. Various arrangements can be employed as in the case shown in the structure.
[0068]
  In addition, the shape of the refracting surface 3 of the microlens array 7 of the present invention and the shape of the opening 4 provided in the light-shielding portion 5 are similar and have the same center of gravity, thereby reducing the energy of diffracted light. Although these are not perfect, some degree of effect can be obtained, and it is only necessary that the positions of the centers of gravity are close to each other with almost similar shapes. Further, when the phase shift portion 6 is formed in an annular shape, it is desirable that the outer peripheral shape and the inner peripheral shape thereof are similar to the refractive surface 3 and have the same center of gravity. Therefore, it is only necessary that the positions of the centers of gravity are close to each other with substantially similar shapes. Further, in the configuration shown in the above description, the light shielding portion 5 is formed on the same surface as the refractive surface 3, but the light shielding portion may be formed on the opposite surface of the surface on which the refractive surface 3 is formed. The effect is obtained.
[0069]
【Example】
  Hereinafter, some examples relating to the microlens 1 or the microlens array 7 of the present invention will be shown, and the effects thereof will be specifically described by comparison with comparative examples.
[0070]
  [Embodiment 1] In this embodiment, it is assumed that a microlens array 7 in which the external shape of the microlens 1 having the structure shown in FIG. First, a quartz glass wafer (substrate 2) having a diameter of 100 mm and a thickness of 525 μm that has been optically polished on both sides is brush scrubbed using a neutral detergent, dried, and then subjected to OAP (Hexa Co., Ltd.) manufactured by Tokyo Ohka Co., Ltd. It was immersed in methyldisilazane) and dried. Thereafter, a positive resist (manufactured by Tokyo Ohka Co., Ltd .: OFFR-800, adjusted to a viscosity of 200 cp) was applied with a spinner, and prebaked at 90 ° C. for 30 minutes in a clean oven. By adjusting the rotation speed of the spinner, a uniform photosensitive resin layer having a thickness of 2.0 μm after pre-baking was formed.
[0071]
  Next, a photomask formed on the center of the photosensitive resin layer with a pattern in which 1280 square patterns of 9 μm × 9 μm are arranged in the X direction and 1024 in the Y direction at 11 μm intervals in both the X and Y directions. And were exposed by an ultraviolet exposure machine. Exposure amount is 300mJ / cm² It was. Next, the photosensitive resin in the ultraviolet irradiation part is removed by dipping in a developing solution (Tokyo Ohka Co., Ltd .: NMD-W developing solution) for 60 seconds to develop a photomask on a quartz glass wafer. A resin film having the same pattern was formed. By holding the quartz glass wafer provided with this resin pattern on a hot plate at 200 ° C. for 10 minutes, the resin pattern was heated and fluidized to change into a convex shape. The height of the convex shape at this time was 2.2 μm.
[0072]
  The quartz glass wafer provided with such a convex resin pattern was etched from the surface provided with the resin pattern using an ECR dry etching apparatus, and the shape was engraved on the surface of the quartz glass wafer. Etching conditions are substrate temperature −40 ° C., microwave (2.54 GHz) power 670 W, ECR ion source coil current 19 A, substrate bias high frequency (13.56 MHz) power 450 W, and etching gas and its supply amount are CHF._Three : Flow rate 15SCCM, O₂ : Flow rate was 1.5 SCCM. The reaction pressure in the etching chamber was set to 0.013 Pa by controlling the opening degree of the variable orifice provided in the exhaust apparatus of the dry etching apparatus. Under these conditions, the etching rate of quartz glass was 120 nm / min, and the etching rate of the resin film was approximately 140 nm / min. Etching was performed until the resin pattern was completely etched under these conditions. The lens height transferred onto the quartz glass wafer surface was 1.9 μm.
[0073]
  Next, the area where the lens array is arranged is cut out into a 20 mm × 17 mm rectangle with an area of about 3 mm in width on the outer periphery, and is polished in parallel from the surface opposite to the surface on which the lens array is formed. The thickness of the substrate excluding was set to 55 μm. The surface opposite to the surface on which the lens array was formed was smoothed by optical polishing, and the surface on which the lens array was formed was temporarily bonded to another quartz glass wafer with a thermoplastic resin soluble in acetone.
[0074]
  Next, a chromium film serving as the light-shielding portion 5 was deposited by sputtering to a thickness of 150 nm on the entire surface opposite to the surface on which the microlenses of the thin microlens array thus fixed were formed.
[0075]
  Next, a positive photoresist is applied on the chromium film, and a photomask in which lines having a width of 1 μm are arranged in a rectangular pattern at intervals of 11 μm in both the X and Y directions is used as a gap between the lens arrays. Aligned, aligned, exposed and developed. The alignment was performed using an exposure machine equipped with an alignment mechanism that can align the front and back surfaces, and simultaneously observing the lens array shape and the photomask lattice pattern that can be seen through the quartz glass wafer and the fixing resin from the back surface. If an alignment mark is provided in advance and a chromium film is not deposited around the alignment mark, an ordinary alignment operation from one side is also possible.
[0076]
  Next, after removing the chromium film other than the resist pattern by wet etching, the resist film was removed by an oxygen ashing apparatus to form a pattern of the light shielding portion 5 having the openings 4.
[0077]
  Next, after applying a positive photoresist to a thickness of 1 μm on the surface on which the chromium film pattern is formed and pre-baking, 1280 square patterns of 7 μm × 7 μm in the X direction at 11 μm intervals in both the X and Y directions, 1024 photomasks each arranged in a direction were aligned with a rectangular pattern with the lens shape and the center aligned, closely contacted, and exposed by an ultraviolet exposure machine. After developing this photoresist, post-baking was performed at 120 ° C. for 30 minutes, and using this as a mask, a magnesium fluoride film serving as a phase shift region was deposited by vacuum deposition. Thereafter, the resist mask was removed by oxygen ashing, the magnesium fluoride film was patterned as a phase shift region, and peeled from the quartz glass wafer used as a pedestal to complete the microlens array 7.
[0078]
  Samples with various thicknesses of magnesium fluoride in the microlens array 7 were prepared, and their light collection performance was examined. In the measurement method, monochromatic and parallel light having a wavelength of 633 nm having a substantially uniform intensity distribution in the arrayed region of the lens array is incident from the surface on which the light-shielding portion 5 is formed, and at a distance of 10 μm from the tip of the microlens. The amount of light transmitted through one rectangular aperture of 5 μm × 5 μm is measured, and the ratio of the amount of light incident on one opening 4 of the light shielding unit 5, that is, the region of 10 μm × 10 μm, is obtained, and the light collected by the microlens Ability. As a result, in the microlens array 7 in which the film thickness of magnesium fluoride is deposited to approximately 120 nm, 95% of the irradiation light amount to the opening 4 of the corresponding light shielding portion 5 is included in the above-described aperture except for the reduction of the light amount due to the surface reflection. % Of light could be collected.
[0079]
  [Embodiment 2] In this embodiment, in the same microlens array as that of Embodiment 1, the magnesium fluoride film serving as the phase shift portion 6 is not located around the refractive surface 3 but only at a position corresponding to the refractive surface 3. This is an example of creating a microlens array 7 patterned in the following manner. The method of patterning the phase shift region is not the lift-off method, but a resist mask is formed on the magnesium fluoride film deposited on the entire surface using a photomask for patterning the microlens portion, and is patterned by a dry etching method. Other structures and production methods were the same as those in Example 1.
[0080]
  Samples with various thicknesses of magnesium fluoride in the microlens array 7 were prepared, and their light collection performance was examined. In the measurement method, a monochromatic, parallel light having a wavelength of 633 nm having a substantially uniform intensity distribution in the arrayed region of the lens array is made incident from the surface on which the light-shielding portion 5 is formed, and at a distance of 10 μm from the tip of the microlens. The amount of light transmitted through one rectangular aperture of 5 μm × 5 μm is measured, and the ratio of the amount of light incident on one opening 4 of the light shielding unit 5, that is, the region of 10 μm × 10 μm, is obtained, and the light collected by the microlens Ability. As a result, in the microlens array substrate having a magnesium fluoride film thickness of about 120 nm deposited, except for a decrease in the amount of light due to surface reflection, 90% of the amount of light irradiated to the opening 4 of the corresponding light-shielding portion 5 within the above-described aperture. % Of light could be collected.
[0081]
  [Comparative Example 1] A microlens array similar to that of Example 1 was prepared without providing a magnesium fluoride film serving as a phase shift portion. Other structures and production methods were the same as those in Example 1.
[0082]
  The light collecting performance of this microlens array was examined. In the measurement method, a monochromatic, parallel light having a wavelength of 633 nm having a substantially uniform intensity distribution in the arrayed region of the lens array is incident from the surface on which the light shielding portion is formed, and is set at a distance of 10 μm from the tip of the microlens. The amount of light transmitted through one rectangular aperture of 5 μm × 5 μm was measured, and the ratio of the amount of light incident on one opening of the light-shielding portion, that is, the region of 10 μm × 10 μm, was determined to be the condensing capability of the microlens. . As a result, excluding a decrease in the amount of light due to surface reflection, the amount of light collected in the aperture described above remained at 75% of the amount of light irradiated to the corresponding light shielding portion opening.
[0083]
  From the difference in condensing ability between the microlens arrays of Examples 1 and 2 and Comparative Example 1, it was confirmed that the condensing performance of the microlens 1 or the microlens array 7 of the present invention was enhanced. In Example 2, the mask for patterning the phase shift region can be shared with the microlens, and although the number of necessary photomasks can be reduced, the light condensing performance is slightly lowered. The cause of this is not clear, but it is thought that the light flux was scattered by the minute roughness of the magnesium fluoride film surface.
[0084]
  [Embodiment 3] In this embodiment, a microlens 1 having a single circular microlens formed on a substrate 2 is produced. First, a quartz glass wafer having a diameter of 100 mm and a thickness of 525 μm that has been optically polished on both sides is subjected to brush scrub cleaning using a neutral detergent, dried, and then OAP (hexamethyldisilazane) manufactured by Tokyo Ohka Co., Ltd. Dipped in and dried. Thereafter, a positive resist (manufactured by Tokyo Ohka Co., Ltd .: OFPR-800, adjusted to a viscosity of 200 cp) was applied by a spinner, and prebaked at 90 ° C. for 30 minutes in a clean oven. By adjusting the rotation speed of the spinner, a uniform photosensitive resin layer having a thickness of 2.0 μm after pre-baking was formed. Next, a photomask in which a circular pattern having a diameter of 9 μm is arranged on the photosensitive resin layer at the center with 10 circular patterns arranged in the X direction and 10 in the Y direction at intervals of 5 mm in both the X and Y directions. It was made to adhere and exposed with the ultraviolet exposure machine. Exposure amount is 300mJ / cm²It was. Next, the photosensitive resin in the ultraviolet irradiation part is removed by dipping in a developing solution (Tokyo Ohka Co., Ltd .: NMD-W developing solution) for 60 seconds to develop a photomask on a quartz glass wafer. A columnar resin film having the same pattern was formed. By holding the quartz glass wafer provided with this resin pattern on a hot plate at 200 ° C. for 10 minutes, the resin pattern was heated and fluidized to change into a convex shape. The height of the convex shape at this time was 2.2 μm.
[0085]
  The quartz glass wafer provided with the above-mentioned convex resin pattern was etched from the surface provided with the resin pattern using an ECR dry etching apparatus, and the shape was engraved on the surface of the quartz glass wafer. Etching conditions are substrate temperature −40 ° C., microwave (2.54 GHz) power 670 W, ECR ion source coil current 19 A, substrate bias high frequency (13.56 MHz) power 450 W, and etching gas and supply amount thereof are CHF._Three : Flow rate 15SCCM, O₂ : Flow rate was 1.5 SCCM. The reaction pressure in the etching chamber was set to 0.013 Pa by controlling the opening degree of the variable orifice provided in the exhaust apparatus of the dry etching apparatus. Under these conditions, the etching rate of quartz glass was 120 nm / min, and the etching rate of the resin film was approximately 140 nm / min. Etching was performed until the resin pattern was completely etched under these conditions. The lens height transferred onto the quartz glass wafer surface was 1.9 μm.
[0086]
  Next, the substrate is cut into a 5 mm × 5 mm rectangle so that the microlens is at the center, and is polished in parallel from the surface opposite to the surface on which the microlens is formed, so that the thickness of the substrate excluding the lens height is 55 μm. It was. The surface opposite to the surface on which the microlenses were formed was optically polished and finished smooth, and the surface on which the microlenses were formed was temporarily bonded to another quartz glass wafer with a thermoplastic resin soluble in acetone.
[0087]
  Next, a chromium film serving as the light-shielding portion 5 was deposited by a sputtering method on the entire surface opposite to the surface on which the microlenses 1 of the thin microlenses 1 thus fixed were formed. Next, a positive photoresist is applied on the chromium film, and an opening 4 having a diameter of 9 μm provided in the center and an annular opening (light transmission region 8) having an inner diameter of 12 μm and an outer diameter of 15 μm concentrically therearound. The photomask having) was aligned with the center of the microlens, exposed, and developed. Alignment was performed using an exposure machine equipped with an alignment mechanism that can align the front and back surfaces, and simultaneously observing the microlens shape and the photomask pattern that can be seen through the quartz wafer and the fixing resin from the back surface. If an alignment mark is provided and a chromium film is not deposited around it, an ordinary alignment operation from one side is also possible.
[0088]
  Next, after removing the chromium film in the opening portion of the resist pattern by wet etching, the resist film was removed by an oxygen ashing device to form a pattern of the light shielding portion 5 having the opening 4. Next, a positive photoresist is applied to the surface on which the chromium film pattern is formed to a thickness of 1 μm, and after prebaking, the photomask on which a circular pattern with a diameter of 10 μm is formed is aligned with the center of the lens and aligned. It was made to adhere and exposed with the ultraviolet exposure machine. After developing this photoresist, post-baking was performed at 120 ° C. for 30 minutes, and using this as a mask, a magnesium fluoride film serving as a region of the phase shift portion 6 was deposited by vacuum evaporation.
[0089]
  Thereafter, the resist mask was removed by oxygen ashing, the magnesium fluoride film was patterned as a phase shift region, and peeled from the quartz glass wafer used as a pedestal to complete the microlens 1.
[0090]
  Samples with various thicknesses of magnesium fluoride of the microlens 1 were prepared, and their light collecting performance was examined. The measurement method is such that a monochromatic, parallel light having a wavelength of 633 nm having a substantially uniform intensity distribution in the microlens region is incident from the surface on which the light-shielding portion 5 is formed, and the diameter is 5 μm set at a distance of 10 μm from the tip of the microlens. The amount of light transmitted through the aperture was measured, and the ratio with the amount of light incident on the opening 4 of the light shielding portion 5, that is, the region having a diameter of 9 μm, was obtained and used as the light collecting ability of the microlens 1. As a result, in the microlens 1 in which the film thickness of magnesium fluoride is deposited to approximately 90 nm, the amount of light that is 95% of the amount of light irradiated to the opening 4 of the light-shielding portion 5 is included in the aperture described above, except for the reduction in the amount of light due to surface reflection. Could be condensed. In the production of the microlens 1, the alignment accuracy when aligning the mask of the phase shift region is relaxed, and the manufacturing cost can be reduced.
[0091]
  [Comparative Example 2] In the same microlens as in Example 3, a microlens without a magnesium fluoride film serving as a phase shift portion was prepared. Other structures and production methods were the same as those in Example 3. The light collecting performance of this microlens was examined. The measuring method is that a monochromatic, parallel light with a wavelength of 633 nm having a substantially uniform intensity distribution in the microlens region is incident from the surface on which the light-shielding part is formed, and the diameter of 5 μm is set at a distance of 100 μm from the tip of the microlens. The amount of light transmitted through the aperture was measured, and the ratio with the amount of light incident on the opening of the light-shielding portion, that is, the region having a diameter of 9 μm, was obtained to determine the condensing ability of the microlens. As a result, the amount of light collected in the aperture was limited to 70% of the amount of light irradiated to the opening of the light shielding portion.
[0092]
  [Embodiment 4] This is an example of creating a microlens array 7 using a region where a large number of protrusions are formed as the structure of the region of the phase shift unit 6. In particular, this is an example of creating a microlens array having the same outer shape of the microlens as in the first embodiment. First, a quartz glass wafer having a diameter of 100 mm and a thickness of 525 μm that has been optically polished on both sides is subjected to brush scrub cleaning using a neutral detergent, dried, and then OAP (hexamethyldisilazane) manufactured by Tokyo Ohka Co., Ltd. Dipped in and dried. Thereafter, a positive resist (manufactured by Tokyo Ohka Co., Ltd .: OFPR-800, adjusted to a viscosity of 200 cp) was applied with a spinner, and prebaked at 90 ° C. for 30 minutes in a clean oven. By adjusting the rotation speed of the spinner, a uniform photosensitive resin layer having a thickness of 2.0 μm after pre-baking was formed.
[0093]
  Next, a photomask formed on the center of the photosensitive resin layer with a pattern in which 1280 square patterns of 9 μm × 9 μm are arranged in the X direction and 1024 in the Y direction at 11 μm intervals in both the X and Y directions. And were exposed by an ultraviolet exposure machine. Exposure amount is 300mJ / cm² It was.
[0094]
  Next, the photosensitive resin in the ultraviolet irradiation part is removed by dipping in a developing solution (Tokyo Ohka Co., Ltd .: NMD-W developing solution) for 60 seconds to develop a photomask on a quartz glass wafer. A resin film having the same pattern was formed. By holding the quartz glass wafer provided with this resin pattern on a hot plate at 200 ° C. for 10 minutes, the resin pattern was heated and fluidized to change into a convex shape. The height of the convex shape at this time was 2.2 μm. The quartz glass wafer provided with such a convex resin pattern was etched from the surface provided with the resin pattern using an ECR dry etching apparatus, and the shape was engraved on the surface of the quartz glass wafer. Etching conditions are substrate temperature −40 ° C., microwave (2.54 GHz) power 670 W, ECR ion source coil current 19 A, substrate bias high frequency (13.56 MHz) power 450 W, and etching gas and supply amount thereof are CHF._Three : Flow rate 15SCCM, O₂ : Flow rate was 1.5 SCCM. The reaction pressure in the etching chamber was set to 0.013 Pa by controlling the opening degree of the variable orifice provided in the exhaust apparatus of the dry etching apparatus. Under these conditions, the etching rate of quartz glass was 120 nm / min, and the etching rate of the resin film was approximately 140 nm / min. Etching was performed until the resin pattern was completely etched under these conditions. The lens height transferred onto the quartz glass wafer surface was 1.9 μm.
[0095]
  Next, the area where the lens array is arranged is cut out into a 20 mm × 17 mm rectangle with an area of about 3 mm in width on the outer periphery, and is polished in parallel from the surface opposite to the surface on which the lens array is formed. The thickness of the substrate excluding was set to 55 μm. The surface opposite to the surface on which the lens array was formed was smoothed by optical polishing, and the surface on which the lens array was formed was temporarily bonded to another quartz glass wafer with a thermoplastic resin soluble in acetone.
[0096]
  Next, a chromium film serving as the light shielding portion 5 was deposited by a sputtering method on the entire surface opposite to the surface on which the lens array of the thin lens array substrate thus fixed was formed, by a sputtering method. Next, a resist for electron beam drawing is applied on the chromium film, and a pattern in which lines having a width of 1 μm are arranged in a rectangular grid at intervals of 11 μm in both the X direction and the Y direction, and the inside of each 10 μm square opening. A pattern in which a circular pattern having a diameter of 0.15 μm is finely arranged at intervals of 0.45 μm in an area having a width of 2 μm along the line is exposed and developed by electron beam drawing.
[0097]
  Next, after removing the chromium film other than the resist pattern by wet etching, the quartz glass of the substrate is removed under the same etching conditions as those in which the lens shape was transferred by an ECR etching apparatus using the resist film and the chromium film as a resist mask. Etched.
[0098]
  In this way, the region of the phase shift portion 6 in which a large number of columnar protrusions were formed and the opening 4 of the light shielding portion 5 were formed simultaneously.
[0099]
  Thereafter, the microlens array 7 was completed by peeling from the quartz glass wafer used as a pedestal.
[0100]
  Samples with various heights of protrusions of the microlens array 7 were prepared, and their light collecting performance was examined. In the measurement method, monochromatic and parallel light having a wavelength of 633 nm having a substantially uniform intensity distribution in the arrayed region of the lens array is incident from the surface on which the light-shielding portion 5 is formed, and is 10 μm away from the tip of the microlens. The amount of light transmitted through one rectangular aperture of 5 μm × 5 μm is measured, and the ratio of the amount of light incident on one opening 4 of the light-shielding portion 5, that is, the region of 10 μm × 10 μm, is obtained, and the light collected by the microlens Ability. As a result, in the microlens array 7 having a projection height of about 0.7 μm, excluding a decrease in the amount of light due to surface reflection, 95% of the amount of light applied to the opening 4 of the corresponding light shielding portion 5 within the above-described aperture. It was possible to collect the amount of light.
[0101]
  Magnesium fluoride is a material having good transmittance even in the ultraviolet region, but it may cause weak absorption at a specific wavelength due to impurities mixed during vapor deposition. However, in the microlens array 7 of the present embodiment in which the substrate is provided with a fine structure and used as the region of the phase shift portion 6, such a problem does not occur.
[0102]
  Further, the same effect can be obtained when the protrusion is formed as a plate.
[0103]
【The invention's effect】
  According to the first aspect of the present invention, a part of the light flux having the wavelength λ that is located at the position overlapping the refractive surface or in the vicinity of the refractive surface and transmitted through the portion so as to interfere with the diffracted light emitted from the refractive surface. Is provided with a phase shift unit that generates a preset optical phase difference, so that when the diffracted light overlaps the focused light from the refracting surface, the condensing spot becomes large, but it passes through the phase shift unit. By appropriately controlling the phase of the light beam and interfering with the diffracted light emitted from the refracting surface, the intensity of this diffracted light is reduced, and the condensing spot is not increased by the diffracted light, improving the resolving power as a lens. In particular, there is no part that blocks the light transmitted through the refracting surface, so the phase shift unit uses only the intensity of the diffracted light from the refracting surface that causes the resolution to decrease without reducing the amount of light. Te can be reduced to enable, even in the case of very fine structures, such as a diameter less than 10 [mu] m, without causing a reduction in transmitted light quantity, it is possible to collect the light beam to a smaller area.
[0104]
  Claim 1The described invention, RankSince it is not necessary to deposit a thin film in forming the phase shift portion, it is possible to provide a highly versatile phase shift portion applicable to more cases even when there is no suitable thin film material.
[0105]
  Claims 2 and 3The invention described inClaim 1In realizing the described invention, it is possible to provide a phase shift unit under conditions that provide better light-collecting characteristics.
[0106]
  Claim 4The described inventionClaims 1 to 3In realizing the described invention, it is possible to provide a phase shift section under conditions where the environmental resistance is enhanced.
[0107]
  Claim 5Since the described invention includes the microlens array having the microlens according to any one of the first to fourth aspects, the amount of transmitted light is reduced even when the array structure is applied to, for example, a liquid crystal projector. The effect that the light condensing property can be enhanced is obtained.
[Brief description of the drawings]
1A and 1B show a microlens according to a first embodiment of the present invention, in which FIG. 1A is a cross-sectional structure diagram, and FIG.
FIG. 2 shows the present invention.As a reference exampleIt is a cross-section figure showing a micro lens of a second embodiment.
FIG. 3 shows the present invention.As a reference exampleIt is sectional structure drawing which shows the micro lens from which 2nd embodiment differs.
FIG. 4 shows the present invention.As a reference exampleIt is sectional structure drawing which shows the micro lens from which 2nd embodiment differs.
FIG. 5 shows the present invention.As a reference exampleIt is sectional structure drawing which shows the micro lens from which 2nd embodiment differs.
FIG. 6 shows the present invention.As a reference exampleIt is a sectional structure figure showing a micro lens array of a second embodiment.
FIG. 7 shows the present invention.As a reference exampleIt is a cross-sectional structure figure which shows the microlens array from which 2nd embodiment differs.
FIG. 8 shows the present invention.As a reference exampleIt is sectional structure drawing which shows the microlens array of 3rd embodiment.
FIG. 9 shows the present invention.As a reference exampleIt is sectional structure drawing which shows the microlens array of 3rd embodiment.
FIG. 10 shows the present invention.As a reference exampleIt is sectional drawing which shows the microlens array from which 3rd embodiment differs.
FIG. 11 shows the present invention.As a reference exampleIt is sectional structure drawing which shows the microlens array of 4th embodiment.
FIG. 12 is a cross-sectional structure diagram illustrating a microlens array according to an embodiment of the present invention.
[Explanation of symbols]
1 Microlens
2 Substrate
3 Refraction surface
4 opening
5 Shading part
6 Phase shift part
8 Light transmission area

Claims (5)

Comprising at least one surface formed spherical or aspherical refractive surface of the base plate, and a light shielding portion having an opening in correspondence to the magnitude of the refractive surface, the micro-diameter of the refractive surface is less than 10 [mu] m In the lens,
A phase shift unit that is located at a position overlapping the refractive surface or at an outer peripheral portion of the refractive surface and that causes an optical phase difference so as to reduce the intensity of the diffracted light by interfering with the diffracted light emitted from the refractive surface. The opening of the light shielding portion is larger than the outer periphery of the refractive surface and has a shape similar to the outer peripheral shape of the refractive surface, and the phase shift portion has an annular shape with a constant width between the outer periphery of the refractive surface and the opening. A microlens comprising a substrate surface structure region in which a large number of columnar protrusions are formed in the substrate region . The columnar projections in the substrate surface structure region satisfy a range in which a ratio P: D2 of a diameter D2 of an inscribed circle of the projection portion to an arrangement pitch P of the projections is 1: 0.1 to 1: 0.5. The microlens according to claim 1, wherein the microlens is formed . The columnar protrusions in the substrate surface structure region are formed so that a ratio D2 : H2 between the height H2 of the protrusions and the diameter D2 of the protrusions satisfies a range of 1: 2 to 1:10. The microlens according to claim 1. 4. The microlens according to claim 1, wherein a transparent material having a refractive index different from that of the protrusion is filled in the protrusion gap portion in the substrate surface structure region . In the micro-lens according to any one of claims 1 to 4, micro, wherein the refractive surface, the opening and the phase shifter has a one-dimensional or two-dimensionally arrayed arrays structure Lens array.

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