JP5201913B2 - Anti-reflection structure and optical device having the same - Google Patents

Description

  The present invention relates to an antireflection structure and an optical device including the same.

  In recent years, various optical elements in which antireflection treatment for suppressing light reflection is performed on the surface have been proposed. As the antireflection treatment, for example, a multilayer formed by alternately laminating a film having a relatively low refractive index (low refractive index film) or a film having a low refractive index and a film having a relatively high refractive index (high refractive index film). A treatment for forming an antireflection film made of a film or the like on the surface is mentioned (for example, Patent Document 1).

  However, such an antireflection film composed of a low refractive index film or a multilayer film requires a complicated process such as a vapor deposition method or a sputtering method when formed. For this reason, there is a problem that productivity is low and production cost is high. Further, an antireflection film made of a low refractive index film or a multilayer film has a problem that the wavelength dependency and the incident angle dependency are relatively large.

In view of such a problem, as an antireflection treatment having a relatively small incident angle dependency and wavelength dependency, for example, a processing for regularly forming minute uneven portions on the optical element surface with a pitch below the wavelength of incident light has been proposed. (For example, Non-Patent Document 1). By performing this process, a rapid change in refractive index at the element interface is suppressed, and the refractive index gradually changes at the element interface. For this reason, reflection on the surface of the optical element is reduced, and a high light incidence rate into the optical element can be realized.
JP 2001-127852 A JP-T-2001-517319 Daniel H. Lagunin (Daniel H. Raguin) By Michael Morris, “Analysis of anti-reflective-structured-frustration-structured-frustration-structured-frustration-structure-frustrated-constitutive-structure-frustrated-constitutive-structure-f-constant-con- stu- Optics), Vol. 32, No. 14 (Vol. 32, No. 14), P.I. 2582-2598, 1993

  However, even when minute irregularities are regularly formed on the optical element surface with a pitch equal to or less than the wavelength of incident light, a sufficiently high reflection suppressing effect may not be obtained.

  This invention is made | formed in view of such a point, The place made into the objective is to provide the antireflection structure which has a high antireflection suppression effect.

  As a result of diligent research, the present inventor has found that reflection of light is not sufficiently suppressed depending on an incident angle when a minute uneven portion is formed on a smooth surface (for example, a smooth surface). It has been found that the reflection of light having a large thickness is not sufficiently suppressed (that is, the reflectivity has an incident angle dependency), and that the fine irregularities are formed on the rough surface. Furthermore, the present inventor has found that although the minute irregularities are formed on the rough surface based on this, the incident angle dependency may not be sufficiently reduced, and the present invention has been made.

  That is, in the configuration in which the minute irregularities are formed on the rough surface, the central axis of the minute irregularities does not necessarily extend in the normal direction of the rough surface (specifically, the tangent plane of the rough surface). It will be in the state inclined with respect to various angles.

  By the way, from the viewpoint of the reflection suppressing effect, it is preferable that the minute uneven portion has a large aspect ratio. However, as described above, in the configuration in which the central axis of the minute uneven portion is inclined with respect to the tangential plane of the rough surface, the normal direction from the tangential plane of the rough surface of the minute uneven portion is sufficient even if the aspect ratio is sufficiently large. When the height to the surface (that is, the distance in the normal direction of the tangent plane from the tangential plane of the rough surface to the apex of the minute uneven portion) is low, light incident from the normal direction of the tangential plane of the rough surface On the other hand, the reflection suppressing effect cannot be sufficiently exhibited.

  Therefore, the present invention secures the height of the minute irregularities in the normal direction from the tangent plane by defining the inclination angle of the rough tangent plane.

  Specifically, the present invention is directed to an antireflection structure that suppresses reflection of light having a predetermined wavelength or longer. The antireflection structure includes a plurality of minute uneven portions formed on a surface having a roughness shape having a surface roughness larger than the predetermined wavelength and regularly arranged with a period equal to or less than the predetermined wavelength. The surface is configured such that the angle formed by the normal vector of the roughness-shaped tangent plane and the normal vector of the reference surface of the surface is 62 degrees or less.

  In the present specification, the “roughness shape” means a shape obtained by cutting off a minute uneven portion from a surface shape as a high-frequency component. In addition, the “reference surface” refers to a surface obtained by cutting off a minute uneven portion and a roughness shape as a high frequency component.

  Another optical device according to the present invention includes the antireflection structure.

  According to the present invention, an antireflection structure in which generation of unnecessary light such as reflected light is sufficiently suppressed can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, the form of the antireflection structure according to the present invention will be described by taking the diffusion plate embodying the present invention as an example. However, the antireflection structure according to the present invention is not limited to the following form, and may be, for example, a constituent member of various optical devices such as a display device, an imaging device, a lighting device, and a projector. Good.

  FIG. 1 is a perspective view of a diffusion plate 1 according to this embodiment.

  FIG. 2 is a partial cross-sectional view of the diffusion plate 1.

  The diffusing plate 1 according to the present embodiment is a plane material having a substantially rectangular shape in plan view, and diffuses and transmits light (specifically, at least diffused and transmitted light whose reflection is suppressed by the minute uneven portion 11 described below) To make it happen). The diffusing plate 1 according to the present embodiment is disposed on the front surface of a display or the like, for example, and suppresses reflection of light (reflection of external light or the like) on the display surface. The material of the diffusion plate 1 is not particularly limited, but may be made of resin or glass. Further, fine particles or the like may be dispersed and mixed.

  In this embodiment, as shown in FIGS. 2 and 3, the surface 10 of the diffuser plate 1 has a period P (preferably, the shortest wavelength λ of the incident light 20 of the incident light 20 of the diffuser plate material. A plurality of minute concavo-convex portions 11 regularly arranged with a period equal to or less than a value divided by the refractive index n, that is, P ≦ λ / n, is formed (hereinafter, a reflection in which a plurality of the minute concavo-convex portions 11 are formed). The prevention structure may be referred to as “SWS”). For this reason, an abrupt refractive index change between the surface 10 of the diffusing plate 1 and the air layer is suppressed, and the refractive index gently changes in the surface layer portion of the surface 10 on which the minute uneven portions 11 are formed. Therefore, as shown in FIGS. 2 and 3, the reflection on the surface 10 of the diffuser plate 1 is effectively suppressed by forming the minute irregularities 11.

  The shape of the minute uneven portion 11 is not particularly limited as long as it has a function of smoothing the refractive index change at the interface between the surface 10 and the air layer. May be chamfered or R-chamfered) concave or convex, truncated pyramid-shaped (ridge may be chamfered or R-chamfered) concave or convex, linear (cross-sectional shape is triangular, It may be a concave or convex portion having a trapezoidal shape, a rectangular shape or the like (the ridge portion may be chamfered or rounded).

  The minute irregularities 11 may be formed such that their heights H are different from each other on the surface 10, but are formed so that their heights H are substantially the same from the viewpoint of ease of creation. It is preferable. Here, the height H of the minute concavo-convex portion 11 is defined by the distance between two points that are the farthest away in the normal direction of the reference surface 12 of the surface 10 in the minute concavo-convex portion 11. In the case of the shape, as shown in FIG. 2, it is defined by the distance from the apex of the cone to the lowest part.

  Further, for example, in the case where the minute uneven portion 11 is a cone-shaped concave portion or a cone-shaped convex portion, the plurality of minute uneven portions 11 are formed by connecting the bottom center and the top portion of the cone. It is preferable that the central axes are formed so as to be substantially parallel to each other. In this case, the diffusion plate 1 can be easily manufactured by injection molding. In addition, for example, when the minute concavo-convex portion 11 is a linear concave portion or a linear convex portion having a triangular cross section, the plurality of fine concavo-convex portions 11 are formed by connecting the bottom center and the top portion in the cross section. It is preferable that the shafts are formed so as to be substantially parallel to each other (for example, each portion having a size of 1 mm square).

  As described above, since the plurality of minute uneven portions 11 are formed on the surface 10, reflection of light on the surface 10 is suppressed. However, when the minute uneven portion 11 is formed on the smooth surface, regular reflection on the surface 10 cannot be sufficiently suppressed.

  FIG. 4 is a graph showing the reflected light intensity of light incident at an incident angle of 45 degrees.

  As shown in FIG. 4, when the minute uneven portion 11 is formed on the smooth surface, reflected light having an emission angle of about 45 degrees, that is, regular reflection is observed. Thus, when the surface 10 on which the minute irregularities 11 are formed is a smooth surface, regular reflection of the incident light 20 cannot be sufficiently suppressed.

  On the other hand, when the fine irregularities 11 are formed on a rough surface having a surface roughness larger than the wavelength of the incident light 20, regular reflection is not substantially observed.

  Here, in the present embodiment, the minute uneven portion 11 is formed on the surface 10 which is a rough surface having a surface roughness larger than the wavelength of the incident light 20. Specifically, the surface 10 is formed to have a surface roughness larger than the wavelength of the incident light 20 with a maximum height roughness Rz defined by ISO 4287: 1997 (corresponding to JIS B0601: 2001). Therefore, in the diffusing plate 1 in the present embodiment, regular reflection on the surface 10 is also sufficiently suppressed. However, the effect of suppressing the occurrence of regular reflection tends to decrease if the surface roughness of the surface 10 is too large. A preferable range of the surface roughness Rz of the surface 10 is 100 μm or less. More preferably, it is 50 micrometers, More preferably, it is 30 micrometers.

  In addition, as shown in FIG. 5, when the minute uneven portion 11 (SWS) is formed on the smooth surface, a sufficient reflection suppressing effect cannot be imparted to light having a relatively large incident angle. That is, the reflectance depends on the incident angle. On the other hand, in the present embodiment, the surface 10 on which the minute irregularities 11 (SWS) are formed is formed with a surface roughness larger than the wavelength of incident light on the surface 10, and as shown in FIG. In addition, the dependency of the reflectance on the incident angle is small, and a high reflection suppressing effect can be obtained even for light having a relatively large incident angle.

FIG. 6 shows the normal vector N ₂ and the surface of the tangent plane 13 of the roughness shape of the surface 10 (in other words, the shape including the minute unevenness portion 11 of the surface 10 cut off from the shape including the minute unevenness portion 11 as a high frequency component). the angle between the normal vector N ₁ of the reference plane 12 of the 10 theta (see FIG. 7) is a graph showing the correlation between the reflectance.

  As shown in FIG. 6, when the angle θ formed is 0 degree (that is, a smooth surface), a large incident angle exceeding 50 degrees, for example, even when the minute uneven portion 11 is formed, Further, in the case of a large incident angle exceeding 70 degrees, the reflectivity tends to increase as the incident angle increases. On the other hand, as the angle θ formed increases from 0 degree, the dependency of the reflectance on the incident angle is reduced, and a high reflection suppressing effect can be obtained even for light having a large incident angle.

  Specifically, it is preferable that the ratio per unit area (for example, 1 mm square) occupied by a portion having an angle θ of 5 degrees or less is less than 80%. In other words, it is preferable that a ratio per unit area occupied by a portion having an angle θ of 5 degrees or more is 20% or more. In this case, the reflectance of light having an incident angle of 89 degrees can be reduced by about 30% as compared with the case where the minute irregularities 11 are formed on the smooth surface. Moreover, it is preferable that the ratio per unit area occupied by the portion having an angle θ of 10 degrees or less is less than 90%. In other words, it is preferable that a ratio per unit area occupied by a portion having an angle θ of 10 degrees or more is 10% or more. Also in this case, the reflectance of light having an incident angle of 89 degrees can be reduced by about 30% as compared with the case where the minute irregularities 11 are formed on the smooth surface.

  More preferably, the ratio per unit area occupied by the portion having an angle θ of 5 degrees or less is preferably less than 50%. In other words, it is preferable that a ratio per unit area occupied by a portion having an angle θ of 5 degrees or more is 50% or more. Moreover, it is preferable that the ratio per unit area occupied by the portion having an angle θ of 10 degrees or less is less than 80%. In other words, it is preferable that a ratio per unit area occupied by a portion having an angle θ of 10 degrees or more is 20% or more. In this case, the reflectance of light having an incident angle of 89 degrees can be reduced by about 50% as compared with the case where the minute irregularities 11 are formed on the smooth surface.

  More preferably, the ratio per unit area occupied by the portion having an angle θ of 5 degrees or less is preferably less than 30%. In other words, the ratio per unit area occupied by the portion where the angle θ formed is 5 degrees or more is preferably 70% or more. Moreover, it is preferable that the ratio per unit area occupied by the portion where the formed angle θ is 10 degrees or less is less than 50%. In other words, it is preferable that a ratio per unit area occupied by a portion having an angle θ of 10 degrees or more is 50% or more. In this case, the reflectance of light having an incident angle of 89 degrees can be reduced by about 70% compared to the case where the minute uneven portion 11 is formed on the smooth surface.

Next, a preferable range of the average value θ _ave of the angle θ formed will be described.

FIG. 8 is a graph showing the correlation between the average value θ _ave and the reflectance.

As shown in FIG. 8, as the average value θ _ave increases, the incident angle dependency decreases, and a high reflection suppressing effect can be obtained even for light having a relatively large incident angle. Specifically, the average value θ _ave is preferably 5 degrees or more. In this case, the reflectance of light having an incident angle of 89 degrees can be reduced by about 30% as compared with the case where the minute irregularities 11 are formed on the smooth surface. More preferably, the average value θ _ave is 10 degrees or more. In this case, the reflectance of light having an incident angle of 89 degrees can be reduced by about 50% as compared with the case where the minute irregularities 11 are formed on the smooth surface. More preferably, the average value θ _ave is 15 degrees or more. In this case, the reflectance of light having an incident angle of 89 degrees can be reduced by about 30% as compared with the case where the minute irregularities 11 are formed on the smooth surface.

  Also, the peak of the distribution of the angle θ formed (the value of the angle θ formed most frequently) is preferably greater than 0 degrees, preferably 2 degrees or more, and more preferably 5 degrees or more.

From the viewpoint of manufacturing, there is a region where the angle θ formed by the normal vector N ₂ of the tangential plane 13 of the surface 10 and the normal vector N ₁ of the reference surface 12 of the surface 10 is larger than 90 degrees. Preferably not. In other words, the surface 10 is preferably substantially constituted by a surface having an angle θ ≦ 90 degrees formed by the roughness shape. As shown in FIG. 9, when there is a region where the angle θ formed is larger than 90 degrees, it is difficult to form the minute uneven portion 11 on the portion of the surface 10 facing the recessed portion 17.

  Further, the minute uneven portion 11 does not necessarily have to exhibit a reflection suppressing effect with respect to all the incident light 20. For example, although the wavelength of the incident light 20 covers a wide wavelength range including ultraviolet light, near-ultraviolet light, visible light, near-infrared light, and infrared light, only reflection of light having a wavelength of 400 nm to 700 nm in the visible light region. Should be suppressed. In this case, since the refractive index n of the resin material of a general diffusion plate is about 1.5 with respect to the period P of the minute concavo-convex part 11 in FIGS. 2 and 3, the period (P ≦ λ / n) is 280 nm or less. It is preferable that On the other hand, the height H of the minute uneven portion 11 is preferably 0.4 times or more (H ≧ 0.4λ) of the incident light wavelength, and preferably 0.4 times or more of 700 nm, that is, 280 nm or more. .

  Further, from the viewpoint of realizing a high reflection suppressing effect, the height H (the height of the virtual cone shape in FIG. 1) of the minute uneven portion 11 is 0.4λ (for example, 280 nm in the visible light region) or more. In addition, the center height H1 (height in the normal direction of the reference surface 12 from the roughness-shaped tangential plane 13 to the apex of the minute irregularities) of the minute irregularities 11 shown in FIG. For example, in the case of the visible light region, it is preferably 280 nm) or more.

  Furthermore, from the viewpoint of realizing a high reflection suppression effect even with respect to incident light that is inclined with respect to the reference surface 12 (for example, the height of the minute uneven portion is 280 nm or more), the minute amount shown in FIG. The slope height H2 of the concavo-convex portion 11 (the height lowered from the apex of the fine concavo-convex portion to the roughness-shaped tangent plane 13 in the vertical direction (the tangential plane 13 from the roughness-shaped tangential plane 13 to the apex of the minute irregularities Is preferably 0.4λ (for example, 280 nm in the case of a visible light region) or more.

  Specifically, in the configuration in which the surface of the diffusion plate 1 on which the minute irregularities 11 are formed is a rough surface, the minute irregularities 11 have a central axis with respect to the rough surface, that is, the rough tangent plane 13. Inclined at various angles. Here, it is preferable that the aspect ratio of the minute uneven portion 11 is large. However, not only the aspect ratio but also the roughness-shaped tangential plane 13 is incident on light incident from a direction orthogonal to the roughness-shaped tangential plane 13. The distance in the normal direction of the tangent plane 13 from the top to the top of the minute uneven portion 11, that is, the slope height H2, is important.

  On the other hand, as a method for forming a structure having a very fine shape as described above, there are manufacturing methods such as an electron beam drawing method and a photolithography method. In such a manufacturing method, the resist is finely processed by irradiation with an electron beam or light. However, when the period is very small as in the case of an antireflection structure, if the height of the fine pattern of the resist is excessively large, There is a risk that surface tension acting between the fine pattern and the developer increases, causing surface tilt that causes the fine pattern to fall. As a height at which the resist pattern having a period (280 nm or less) of the antireflection structure (that is, the minute uneven portion 11) does not cause surface tilt, the aspect ratio (the ratio of the height H to the period P of the minute uneven portion, that is, H / P) is preferably 3 or less.

From the above viewpoint, in order to satisfy the inclination height H2 ≧ 280 [nm] for the visible light range while setting the aspect ratio to 3 or less, if the pitch P ≦ 280 [nm] as described above, the roughness shape The angle θ formed by the normal vector N ₂ of the tangential plane 13 and the normal vector N ₁ of the reference surface 12 of the surface 10 is preferably 62 degrees (specifically 61.34 degrees) or less. In other words, by setting the angle θ to be 62 degrees or less, the aspect ratio of the minute concavo-convex portion 11 is set to 3 or less, and the inclination height H2 is reduced by light that is intended to suppress reflection. A high antireflection effect can be realized by securing 0.4 times or more the minimum wavelength of visible light. At this time, the central axis of the minute uneven portion 11 extends in the normal direction of the reference plane 12.

In the case where the central axis of the minute uneven portion 11 does not extend in the normal direction of the reference surface 12, an angle formed by the normal vector N ₂ of the rough tangent plane 13 and the central axis of the minute uneven portion 11 ( By making the angle of 90 degrees or less larger than 28 degrees (specifically, 28.66 degrees), the aspect ratio of the minute concavo-convex portion 11 is set to 3 or less, and the tilt height H2 is reduced while preventing the surface from falling down. In addition, a high reflection suppressing effect can be realized by securing 0.4 or more times the minimum wavelength of visible light, which is the light for suppressing reflection.

In addition, when the diffusion plate 1 having the shape as described above is produced by molding, it is preferable that the aspect ratio of the minute uneven portion 11 is 2 or less in consideration of difficulty of molding. Therefore, in order to satisfy the inclination height H2 ≧ 280 [nm] for the visible light range while setting the aspect ratio to 2 or less, if the pitch P ≦ 280 [nm] as described above, the roughness-shaped tangential plane is set. The angle θ formed by the normal vector N _{2 of} 13 and the normal vector N ₁ of the reference surface 12 of the surface 10 is preferably 47 degrees (specifically, 46.94 degrees) or less. In other words, by making the size of the angle θ to be 47 degrees or less, the inclination height H2 is light that is intended to suppress reflection while facilitating the molding by setting the aspect ratio of the minute uneven portion 11 to 2 or less. A high reflection suppression effect can be realized by securing 0.4 times or more the minimum wavelength of visible light. At this time, the central axis of the minute uneven portion 11 extends in the normal direction of the reference plane 12.

In the case where the central axis of the minute uneven portion 11 does not extend in the normal direction of the reference surface 12, an angle formed by the normal vector N ₂ of the rough tangent plane 13 and the central axis of the minute uneven portion 11 ( By making the angle of 90 degrees or less larger than 43 degrees (specifically, 43.06 degrees), the aspect ratio of the fine irregularities 11 is set to 2 or less, while facilitating molding, and the inclination height H2 is A high reflection suppression effect can be realized by securing 0.4 times or more the minimum wavelength of visible light, which is the light for suppressing reflection.

Therefore, according to the present embodiment, the angle θ formed by the normal vector N _{2 of} the rough tangent plane 13 and the normal vector N ₁ of the reference surface 12 of the surface 10 is set to 62 degrees or less. Thus, it is possible to achieve a high reflection suppressing effect while preventing surface collapse.

More preferably, the angle θ formed by the normal vector N ₂ of the rough tangent plane 13 and the normal vector N ₁ of the reference surface 12 of the surface 10 is set to 47 degrees or less to facilitate molding. In addition, a high reflection suppression effect can be realized.

Further, by setting the average value θ _ave of the angle θ formed by the normal vector N _{2 of} the rough tangent plane 13 and the normal vector N ₁ of the reference surface 12 of the surface 10 to be 5 degrees or more, the incident angle is A relatively large light reflectance can be suppressed as compared with the configuration in which the minute unevenness 11 is formed on the smooth surface. The average value θ _ave is preferably 10 degrees or more, and more preferably 15 degrees or more.

Further, the portion where the angle θ formed by the normal vector N _{2 of} the rough tangent plane 13 and the normal vector N ₁ of the reference surface 12 of the surface 10 is 5 degrees or less per unit area (for example, 1 mm square). By making the ratio to less than 80%, it is possible to suppress the reflectance of light having a relatively large incident angle as compared with the configuration in which the minute irregularities 11 are formed on the smooth surface. Further, it is more preferable that the ratio of the portion where the formed angle θ is 10 degrees or less per unit area is less than 90%.

Furthermore, the surface 10 is such that there is no region where the angle θ formed by the normal vector N _{2 of} the rough tangent plane 13 and the normal vector N ₁ of the reference surface 12 of the surface 10 is greater than 90 degrees. By forming the concavo-convex portion 11 on the surface 10 can be easily formed.

  In addition, by forming the minute concavo-convex portions 11 so that the central axes thereof are parallel to each other, it is possible to easily manufacture the diffusion plate 1 by injection molding.

  Heretofore, the light transmissive diffusion plate 1 has been described as an example. However, the antireflection structure according to the present invention is not limited to the light transmissive structure, for example, a light absorbing structure. A so-called black body may be used.

  Here, an example in which the SWS is directly formed on the surface 10 of the diffusing plate 1 has been described, but the surface 10 may be formed by sticking or adhering a seal formed with SWS on a smooth surface. . In other words, the diffusing plate 1 may not be integrated, and may be constituted by a plurality of constituent members.

  Although an example in which the SWS is formed over the entire surface 10 has been described here, the SWS is not necessarily provided over the entire surface 10, and the SWS may be formed only at a necessary position. In this case, not only the location where the SWS is provided, but also the other location on the surface 10 may be a rough surface having the same surface roughness as the location where the SWS is provided. It is good. Furthermore, another antireflection structure such as a multilayer film of a film having a relatively low reflectance and a film having a relatively high reflectance may be formed at a location where the SWS is not provided. In addition, even within the region where the SWS is formed, the height and period (pitch) of the SWS may be adjusted as necessary.

  Since the antireflection structure according to the present invention sufficiently suppresses generation of unnecessary light such as reflected light, various optical devices such as an imaging device, an illumination device, an optical scanning device, an optical pickup device, and a display are used. Useful for.

It is a perspective view of a diffusion plate. It is a fragmentary sectional view of a diffusion plate. It is an enlarged view of the partial cross section of a diffusion plate. It is a graph showing the reflected light intensity of the light which injects with an incident angle of 45 degree | times. It is a graph showing the correlation of an incident angle and a reflectance. It is a graph showing the correlation with the angle | corner (theta) and reflectance which are made. It is sectional drawing showing the roughness shape which removed the fine uneven | corrugated | grooved part. It is a graph showing the correlation with average value (theta) _ave and a reflectance. It is sectional drawing for demonstrating the case where the angle | corner θ to make is larger than 90 degree | times.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diffusion plate 10 Surface 11 Minute uneven part 12 Reference surface 13 Tangent plane

Claims (9)

An antireflection structure that suppresses reflection of light of a predetermined wavelength or more,
The predetermined wavelength is 400 nm,
A plurality of surface roughnesses that are formed on a surface having a maximum height roughness Rz defined by ISO 4287: 1997 and having a roughness shape larger than the predetermined wavelength, and regularly arranged with a period equal to or less than the predetermined wavelength. It has a minute uneven part,
The minute uneven portion has a height of 0.4 times or more of the predetermined wavelength,
The antireflection structure, wherein the surface is configured such that an angle formed by a normal vector of the rough tangent plane and a normal vector of the reference surface of the surface is 62 degrees or less. The antireflection structure according to claim 1,
The antireflection structure, wherein the surface is configured such that an angle formed by a normal vector of the rough tangent plane and a normal vector of the reference surface is 47 degrees or less. The antireflection structure according to claim 1 or 2 ,
An antireflection structure that transmits light in which the reflection is suppressed. The antireflection structure according to claim 1 or 2 ,
Each said fine uneven | corrugated | grooved part is a reflection preventing structure which is a substantially cone-shaped recessed part or convex part, or a linear concave part or a linear convex part. The antireflection structure according to claim 1 or 2 ,
The surface is an antireflection structure having a maximum surface roughness Rz defined by ISO 4287: 1997 and less than 100 μm. The antireflection structure according to claim 1 or 2 ,
The above-mentioned surface is an antireflection structure whose surface roughness is less than 50 μm in the maximum height roughness Rz defined by ISO4287: 1997. The antireflection structure according to claim 1 or 2 ,
The surface is an antireflection structure having a maximum surface roughness Rz defined by ISO 4287: 1997 and less than 30 μm. The antireflection structure according to claim 1 or 2 ,
Each of the micro concavo-convex portions is a conical concave portion or a conical convex portion, and the antireflection structure is configured such that the central axes connecting the center of the bottom and the top are substantially parallel to each other. . Optical device including an anti-reflection structure according to claim 1 or 2.

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