Optical element and optical device

Abstract

To provide an optical element that has uniform optical performance despite ease of manufacture.SOLUTION: An optical element (100) has a substrate (2) having a curved face, a plurality of projections (3) arranged along a first direction on the curved face, and electric conductors (4) provided respectively on the plurality of projections. The plurality of projections each extend in a second direction perpendicular to the first direction, and project in a third direction perpendicular to both the first direction and the second direction. The electric conductors each cover at least part of an end face, at least part of a first side face, and at least part of a second side face, of each of the plurality of projections. When an arrangement pitch of the plurality of projections is defined as P (nm), and the thickness in the first direction of the electric conductor on the outside in the third direction of the end face, for each of the plurality of projections, is defined as Ax (nm), the conditional expression of 0.25≤Ax / P≤0.55 is satisfied.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an optical element and an optical device. [Background technology]

[0002] There is a demand for miniaturization of optical devices equipped with observation optical systems such as head-mounted displays (HMDs) and electronic viewfinders (EVFs). Patent Document 1 discloses an observation optical system (VR optical system) that uses two semi-transmitting surfaces. Patent Document 1 also discloses that a film-like wire-grid polarizer is used as a polarization-selective transmission / reflection element on one of the two semi-transmitting surfaces. Patent Document 2 discloses a method for producing a film-like wire-grid polarizer by forming a lattice-like uneven structure while winding a rolled substrate film, and depositing a metal by oblique vapor deposition while changing the vapor deposition angle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-81530 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-39183 Summary of the Invention [Problem to be solved by the invention]

[0004] The film-like wire-grid polarizers disclosed in Patent Documents 1 and 2 must be attached to the surface of an optical element such as a lens with desired surface accuracy, but the attachment process is complicated. Furthermore, with the configurations disclosed in Patent Documents 1 and 2, it is difficult to achieve uniform polarization characteristics (optical characteristics).

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an optical element that is easy to manufacture and has uniform, high optical performance. [Means for solving the problem]

[0006] An optical element according to one aspect of the present invention comprises a substrate having a plurality of convex portions arranged along a first direction, and a conductor provided on each of the plurality of convex portions, each of the plurality of convex portions extending in a second direction perpendicular to the first direction, and in a cross section including the first direction and a third direction perpendicular to each of the first and second directions, each of the plurality of convex portions protruding in the third direction and having an upper surface, a first side surface, and a second side surface opposite to the first side surface, and in the cross section, the conductor covers at least a part of the upper surface, at least a part of the first side surface, and at least a part of the second side surface of each of the plurality of convex portions, and when an arrangement pitch of the plurality of convex portions is P (nm) and a thickness in the first direction of the conductor above the convex portion for each of the plurality of convex portions is Ax (nm), 0.25≦Ax / P≦0.55 The following condition is satisfied.

[0007] Other objects and features of the present invention are illustrated in the following examples. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an optical element that is easy to manufacture and has uniform optical performance. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a front view of a transflective element in each example. [Figure 2] 3 is an enlarged cross-sectional view of a portion of a transflective element in each example. FIG. [Figure 3] FIG. 2 is an explanatory diagram of the shape of a conductor in each example. [Figure 4] FIG. 2 is a side view of the transflective element in the first embodiment. [Figure 5] FIG. 3 is a diagram showing transmittance and reflectance in Example 1. [Figure 6] FIG. 1 is a side view of a transmission-reflection element serving as a first comparative example. [Figure 7] FIG. 10 is a diagram showing transmittance and reflectance as Comparative Example 1. [Figure 8] FIG. 10 is a side view of the transflective element in the second embodiment. [Figure 9] FIG. 10 is a diagram showing transmittance and reflectance in Example 2. [Figure 10] FIG. 10 is a side view of a transmission-reflection element serving as a second comparative example. [Figure 11] FIG. 10 is a diagram showing transmittance and reflectance as Comparative Example 2. [Figure 12] FIG. 10 is a side view of a transflective element according to a third embodiment. [Figure 13] FIG. 10 is a diagram showing transmittance and reflectance in Example 3. [Figure 14] FIG. 10 is a side view of a transflective element according to a fourth embodiment. [Figure 15] FIG. 10 is a diagram showing transmittance and reflectance in Example 4. [Figure 16] FIG. 10 is a side view of a transflective element according to a fifth embodiment. [Figure 17] FIG. 10 is a diagram showing transmittance and reflectance in Example 5. [Figure 18] FIG. 13 is a side view of a transflective element according to a sixth embodiment. [Figure 19] FIG. 10 is a diagram showing transmittance and reflectance in Example 6. [Figure 20] FIG. 13 is a side view of the transflective element in Example 7. [Figure 21] FIG. 10 is a diagram showing transmittance and reflectance in Example 7. [Figure 22] FIG. 13 is a cross-sectional view of an optical system according to an eighth embodiment. [Figure 23] FIG. 13 is a cross-sectional view of an observation device in Example 9. [Figure 24] FIG. 13 is an external view of an observation device in Example 9. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] First, with reference to FIGS. 1 and 2, a transflective element (polarization-selective transflective element, optical element) 100 in each embodiment will be described. FIG. 1 is a front view of the transflective element 100. In FIG. 1, the horizontal direction is the first direction (the arrangement direction of the multiple convex portions 3), and the vertical direction is the second direction (the extension direction of the convex portions 3). FIG. 2 is an enlarged cross-sectional view of a portion of the transflective element 100, and shows a schematic enlargement of a portion of the cross-sectional shape of the transflective element 100 in FIG. 1 cut along line A-A'. In FIG. 2, the direction along the curved surface 2a of the substrate 2 (the arrangement direction of the multiple convex portions 3) is the first direction, and the direction into the paper is the second direction (the extension direction of the convex portions 3). The direction perpendicular to each of the first and second directions is the third direction (surface normal direction 7), which corresponds to the direction in which the convex portions 3 protrude from the substrate 2. The third direction of a specific one of the plurality of protrusions 3 (for example, the protrusion 3 located at the center of the transflective element 100) is the direction along the optical axis 8.

[0012] As shown in Figure 2, the concave-convex structure consisting of multiple convex portions 3 and concave portions formed between two adjacent convex portions 3 extends in one direction (second direction) (extends along one direction). Extending in one direction does not mean that the convex-convex structure needs to extend strictly parallel, but only needs to extend approximately parallel. Note that Figures 1 and 2 are not to the actual scale and are deformed drawings.

[0013] As shown in Fig. 1, a plurality of thin conductor wires 1 extending in the vertical direction are formed on one surface of the transmissive reflector 100. As shown in Fig. 2, the transmissive reflector 100 has a base (substrate) 2, convex portions 3 formed on the base 2 using the same material as the base 2, and conductors 4 formed on the tops (upper surfaces) and both side surfaces (left and right surfaces) of the convex portions 3. That is, a plurality of convex portions 3 are arranged on the surface of the base 2 at a predetermined pitch (arrangement pitch, pitch P) along a first direction (a direction along the curved surface 2a of the base 2). The conductors 4 in Fig. 2 correspond to the thin conductor wires 1 in Fig. 1.

[0014] 2, each of the plurality of protrusions 3 protrudes in the third direction and has an upper surface 3a, a first side surface 3b, and a second side surface 3c opposite the first side surface. That is, each of the plurality of protrusions 3 has an end surface (upper surface 3a) in the third direction, and a first side surface 3b and a second side surface 3c arranged on both sides of the end surface in the first direction.

[0015] The conductor 4 covers at least a portion of the top surface 3a, at least a portion of the first side surface 3b, and at least a portion of the second side surface 3c of each of the multiple protrusions 3. In other words, the conductor 4 includes a first conductor 5 provided on the first side surface of each of the multiple protrusions 3 and a second conductor 6 provided on the second side surface opposite the first side surface. That is, the first conductor 5 is a conductor provided on one side surface (left side surface) from the center of the width of the protrusion 3, and the second conductor 6 is a conductor provided on the other side surface (right side surface) from the center of the width of the protrusion 3. Dx1 (nm) is the thickness of the first conductor 5 at the top of the protrusion 3 in the first direction (the direction along the curved surface 2a of the substrate 2). Dx2 (nm) is the thickness of the second conductor 6 at the top of the protrusion 3 in the first direction.

[0016] The substrate 2 and the multiple convex portions 3 are integrally formed, for example, by injection molding a thermoplastic resin using a lens mold having a concave-convex structure on its surface. Alternatively, a grating may be formed on the lens surface by applying an ultraviolet curable resin to the lens surface and pressing a mold against it.

[0017] The surface shape of the substrate 2 has a curved surface 2a. The convex portions 3 are formed to extend (protrude) along the surface normal direction 7 of the curved surface 2a of the substrate 2. For example, by patterning a concave-convex structure on the mirror-finish surface of an injection mold and then forming the concave-convex structure by etching, it is possible to produce a lens mold in which the convex portions face the surface normal direction 7. By integrally forming the substrate 2 and the convex portions 3, the process of bonding a transmissive-reflective element to the optical element is unnecessary, which reduces disadvantages such as increased manufacturing costs and, in particular, element defects that occur when the surface is curved.

[0018] The material of the substrate 2 may be any material that is transparent in the target wavelength region, such as polymethyl methacrylate (PMMA), polycarbonate resin (PC), cycloolefin resin (COP), cycloolefin copolymer (COC), polystyrene resin (PS), etc. To avoid a decrease in the polarization separation function, it is preferable to reduce the phase change in the light beam at the wavelength used, and it is preferable to use a material with low birefringence properties.

[0019] The thickness of the substrate 2 of the transmissive reflecting element 100 is preferably set to 100 μm or more so that the element can be easily held when incorporated into an optical system having a plurality of lenses, for example.

[0020] 2 (surface viewed from the second direction), the cross-sectional shape of the protrusions 3 is composed of repeated concave and convex shapes, and may be any shape, such as a rectangle, parabola, trapezoid, or triangle, as long as the conductor 4 can be formed on the top surface and both side surfaces of each of the multiple protrusions 3. These cross-sectional shapes do not have to be strict shapes defined mathematically, and the protrusions 3 may have blunted corners at the top or tapered bottoms.

[0021] In each example, the thin conductor wires 1 are obtained by obliquely depositing the conductor 4 on both side surfaces of the protrusions 3 at a fixed angle. For this reason, it is difficult to independently control the height of the conductor 4 deposited above the upper surface of the protrusions 3, and the height of the conductor 4 is highly dependent on the height of the protrusions 3. Since a wire grid polarizer exhibits good polarization separation performance when the conductor 4 has a certain height or more, it is preferable that the height h (nm) of the protrusions 3 in the third direction is similarly high. For this reason, it is preferable that the height h of the protrusions 3 in the third direction satisfy the following conditional expression (1):

[0022] 50≦h≦300 (1) A high height h of the protrusions 3 increases the area of ​​the conductor 4 that adheres to the side surfaces of the protrusions 3, improving adhesion. On the other hand, making the height h extremely large is not preferable because it makes manufacturing difficult. Here, the height h of the protrusions refers to the height in the surface normal direction 7 of the substrate 2.

[0023] More preferably, the numerical range of conditional expression (1) is set as in the following conditional expression (1a).

[0024] 55≦h≦300 (1a) More preferably, the numerical range of conditional expression (1) is set as in the following conditional expression (1b).

[0025] 60≦h≦300 (1b) When the conductor 4 is obtained by the above-described method, the thickness Ax in the first direction of the conductor 4 in the region above the upper surface of the convex portion 3 depends on the width of the convex portion 3. As will be described in detail later, to obtain good polarization separation performance, it is necessary to control the thickness Ax in the first direction of the conductor 4 in the region above the upper surface of the convex portion 3. For this reason, when the width w (nm) of the convex portion 3 in the first direction at half the height h of the convex portion 3 is defined as w, it is preferable that the width w is small. Here, the thickness Ax in the first direction of the conductor 4 may be, for example, the average value of the thickness in the first direction at the height of the apex of the convex portion 3 in the transflective element 100. The width w of the convex portion 3 is the thickness in the first direction at half the height h of the convex portion 3.

[0026] As mentioned above, the height h of the protrusions 3 is preferably 50 nm or more, and by appropriately setting the ratio h / w of the width w to the height h of the protrusions 3, it is possible to achieve both moldability and good polarization separation performance. Fine protrusions with a width w of 10 nm or less are more likely to suffer from defects such as deformation or "seizure" during mold release in the injection molding process. Therefore, it is preferable that the ratio h / w of the width w to the height h of the protrusions 3 satisfy the following conditional expression (2):

[0027] 1.5≦h / w≦8.0 (2) More preferably, the numerical range of conditional expression (2) is set as in the following conditional expression (2a).

[0028] 2.0≦h / w≦7.8 (2a) More preferably, the numerical range of conditional expression (2) is set as in the following conditional expression (2b).

[0029] 3.5≦h / w≦7.5 (2b) In each embodiment, it is preferable that the pitch P (nm) of the plurality of convex portions 3 satisfies the following conditional expression (3).

[0030] 70≦P≦170 (3) Generally, the smaller the pitch P of the conductors 4 of a wire grid polarizer, the better its polarization separation performance over a wide wavelength range. However, if the pitch P is too large for the target wavelength, unwanted light is generated due to diffraction, degrading the polarization separation performance. Therefore, to achieve high polarization separation performance in the visible range, the pitch P is preferably 170 nm or less.

[0031] Furthermore, in order to form a fine uneven structure, the pitch P is preferably 70 nm or more. Setting the pitch P to 70 nm or less is undesirable because it would require the width w of the convex portions 3 in the second direction to be less than 10 nm in order to achieve a preferred range for the relationship between the pitch P and the thickness Ax in the second direction of the conductor in the region above the upper surface of the convex portions 3 (described later). The pitch P does not require the multiple convex portions 3 to be arranged at strictly equal intervals; it is acceptable for there to be a variation of about 10% within the surface due to manufacturing errors, shrinkage, etc., during transfer of the convex portions 3. The pitch P is the distance between the centers of the convex portions 3 in the surface normal direction 7 at the bases of the convex portions 3.

[0032] More preferably, the numerical range of conditional expression (3) is set as in the following conditional expression (3a).

[0033] 75≦P≦165 (3a) More preferably, the numerical range of conditional expression (3) is set as in the following conditional expression (3b).

[0034] 80≦P≦160 (3b) The conductor 4 is preferably made of a material having high reflectivity in the visible light region, such as aluminum, silver, gold, chromium, zirconium, titanium, copper, tungsten, magnesium, tantalum, platinum, or an alloy containing any of these as its main component.

[0035] At least a portion of the top surface and at least a portion of both side surfaces (and at least a portion of the recesses) of the convex and concave portions 3 of the concave-convex structure are covered with a conductor 4 to form thin conductor wires 1. The method for covering the convex portions 3 with the conductor 4 is not limited to vacuum deposition or sputtering, as long as it is a method that can deposit the conductor 4 on the convex portions 3. For example, using oblique deposition in the vacuum deposition method is more preferable because it allows the deposition angle θ to be appropriately set depending on the shape or pitch P of the convex portions 3, making it easier to control the shape of the conductor 4. Here, the deposition angle θ is the angle between the direction along the optical axis 8 and the deposition direction from the deposition source.

[0036] Oblique deposition from a fixed angle is preferred for achieving good polarization separation function while keeping production costs low. When oblique deposition is performed on a convex portion 3, the adjacent convex portion 3 casts a shadow, resulting in some areas where the deposition material does not adhere, and a conductor 4 is formed on one side surface of the convex portion 3. Depending on the incident angle of the deposition material with respect to the convex portion 3, the conductor may also adhere to the concave portion, and an area where the deposition material does not adhere may also be formed on one side surface.

[0037] When the substrate is flat, the conductor formed by oblique deposition from a fixed angle is generally uniform across the surface of the optical element, although there may be some variation due to manufacturing errors. However, in an optical element (curved element) where the substrate is curved, if the conductor 4 is deposited by oblique deposition from a fixed angle toward the convex portion 3 extending in the surface normal direction 7, the film thickness and shape of the conductor 4 will not be uniform in the cross section shown in Figure 2. As a result, roughly divided into four patterns of conductor shapes can be obtained.

[0038] FIG. 3 is an explanatory diagram of the conductor shapes of four patterns (a) to (d). The conductor shape in pattern (a), in which the conductor extends upward from the bottom of the recesses to cover the top surfaces of the protrusions, is the conductor shape with the highest polarization separation performance. Here, the thickness in the first direction of the conductor that coats the side surfaces of the protrusions at the top of the protrusions is defined as Dx (nm). The conductor on the side surfaces of the protrusions is coated with a substantially uniform thickness from the recesses to the top of the protrusions. The incident angle of the deposition material to the protrusions having such a conductor shape is defined as θ1. Here, the incident angle of the deposition material to the protrusions is the angle between the surface normal direction 7 at the center of the width of the protrusions and the deposition direction from the deposition source. In pattern (a), the surface normal direction 7 coincides with the optical axis direction, so the deposition angle θ and the incident angle θ1 coincide.

[0039] When the substrate is a flat plate, oblique deposition of the deposition material onto the convex portions at an incident angle θ1 to form such a conductor shape results in the formation of a conductor shape as shown in pattern (a) in Figure 3 over the entire surface of the optical element.

[0040] On the other hand, when the substrate is curved, the incident angle of the vapor deposition material relative to the convex portions is smaller than θ1 (incident angle θ2) in regions closer to the deposition source than the position where pattern (a), which represents the conductor shape with the highest polarization (optical) characteristics, is formed. In this case, a conductor shape such as pattern (b) in Figure 3 is obtained. The conductor shape of pattern (b) is a shape in which the conductor is deposited in the concave portions to a thickness greater than Dx. Note that the curvature of the substrate in Figure 3 is positive. However, if the curvature is negative, the conductor shape shown in Figure 3(b) will be formed if the incident angle of the vapor deposition material is greater than θ1. In Figure 3, since the curvature of the substrate is positive, if the central region of the optical element is obliquely vapor-deposited at an incident angle θ1 of the vapor deposition material to form the ideal conductor shape shown in Figure 3(a), the region to the left of the center of the optical element will form the conductor shape shown in Figure 3(b). The incident angle of the vapor deposition material relative to the convex portions is θ2 (θ2<θ1). The conductor shape of pattern (b) has a conductor shape such that when the value obtained by subtracting thickness Dx from the maximum thickness of the conductor deposited on the side surface of protrusion 3 in the first direction is Bx (nm), the value Bx is greater than 0. Also, the film thickness in the surface normal direction 7 of the conductor deposited in recesses with a thickness greater than thickness Dx is Bz.

[0041] As the value Bx increases, the incidence angle θ2 of the deposition material deviates from the incidence angle θ1 and also deviates from the ideal conductor shape, resulting in a deterioration in polarization characteristics.

[0042] On the other hand, in regions farther from the deposition source than the optical element position forming the ideal conductor shape, pattern (a), the incident angle of the deposition material to the convex portions becomes larger than θ1, resulting in conductor shapes such as patterns (c) and (d). Here, the curvature of the substrate in Figure 3 is positive. However, if the curvature is negative, the incident angle of the deposition material to the convex portions becomes smaller than θ1, resulting in the formation of conductor shapes such as patterns (c) and (d). The incident angles of the deposition material to the convex portions at this time are θ3 and θ4. This region is located to the right of the center of the optical element in Figure 3. The conductor shape of pattern (c) has a height Sz (nm) in the third direction of a region lacking the conductor deposited on the side of the convex portions near the substrate. The conductor shape of pattern (d) is formed in a region where the incident angle of the deposition material is even larger than the incident angle θ3, and has a region of height Sz and a region of height Nz (completely uncoated region). The completely undeposited region is a region having a height Nz (nm) in the third direction of a region where no film is deposited on the side surface of the convex portion.

[0043] As the region of height Sz becomes smaller and the completely uncoated region of height Nz becomes larger, the angles of incidence θ3 and θ4 become more distant from the angle of incidence θ1 and the shape of the conductor becomes less ideal, resulting in a deterioration in polarization separation performance.

[0044] In the conductor shape of pattern (a) in Figure 3, Bx, Sz, and Nz are all 0. In summary, when oblique deposition is performed from a fixed angle on convex portions extending in the surface normal direction of a curved substrate, four patterns of conductor shapes are formed where Bx = 0 and Sz = 0, or Bx > 0, or Sz > 0 and Nz = 0, or Sz > 0 and Nz > 0. Note that Figure 3 is a schematic diagram that shows only the four patterns of conductors and the convex portions adjacent to the conductors in the deposition direction, omitting other configurations. In reality, the convex portions are arranged at equal intervals according to the pitch of the convex portions, and the conductor is deposited on them.

[0045] In Figure 3, four patterns of conductor shapes within the plane of the optical element and only the convex portions adjacent to the conductors in the deposition direction are shown. However, in reality, multiple convex portions and conductors exist between the four patterns of conductors. Furthermore, because the substrate is curved, the conductor shapes between the four patterns change continuously or stepwise within the plane of the optical element. Dx, Bx, Sz, and Nz also change continuously or stepwise from one end to the other end in the first direction of the optical element. As a result, the conductor shapes within the plane of the optical element become non-uniform, causing changes in the polarization characteristics (optical characteristics).

[0046] Therefore, in each embodiment, at least a portion of the top surface and at least a portion of both side surfaces of the convex portions (and at least a portion of the concave portions) are covered with a conductor, thereby minimizing changes in the shape of the conductor within the plane of the optical element, thereby achieving good polarization separation performance. To obtain a conductor of this shape, the conductor is deposited on the top surface and one side surface of the convex portions and at least a portion of the concave portions by oblique evaporation from a fixed angle. The optical element is then rotated 180 degrees, and the conductor is deposited on the other side surface of the convex portions by oblique evaporation from a similar fixed angle, thereby forming a conductor on the top surface and both side surfaces of the convex portions and at least a portion of the concave portions. The deposition angles for the first and second depositions may be the same or different. It is preferable to optimally adjust the deposition angle for the second deposition, taking into account the shape of the conductor deposited in the first deposition.

[0047] When a conductor is deposited on both side surfaces of a protrusion extending in the surface normal direction 7 of a curved substrate by oblique evaporation from a fixed angle twice, Dx1 of the first conductor 5 increases continuously or stepwise in the direction away from one end of the optical element in the first direction, while Dx2 of the second conductor 6 decreases continuously or stepwise in the direction away from one end of the optical element in the first direction.

[0048] Furthermore, after forming the conductors on one side, the optical element is rotated 180 degrees and the conductors on the other side are formed, so that in the cross section of Figure 2, the shapes of the first conductors 5 and the second conductors 6 formed on each of the multiple protrusions 3 have regions where they are asymmetric with each other. That is, the conductors 4 (first conductors and second conductors) have shapes that are asymmetric with respect to an axis in the third direction (plane normal direction 7) that passes through the center of each of the multiple protrusions 3. Therefore, within the plane of the optical element, the conductor shapes of the first conductors 5 and second conductors 6 have at least two of the four patterns of conductor shapes.

[0049] The number of patterns in the conductor shape can be changed by adjusting the deposition angle. Here, Bx, Sz, and Nz change continuously or stepwise from one end to the other end of the optical element in the first direction. By forming such a conductor shape, the change in the conductor shape of each convex portion within the surface of the optical element can be reduced compared to the change in conductors formed by conventional oblique deposition from a fixed angle on one side of the convex portion. Therefore, the change in polarization separation performance can also be reduced.

[0050] Furthermore, in order to exhibit good polarization characteristics while reducing changes in the polarization characteristics within the plane of the optical element, it is preferable that the first conductor and the second conductor within the plane of the optical element satisfy the following conditional expressions (4) and (5).

[0051] (Bx+Dx) / (Pw)<0.40 (4) (h-Nz) / h>0.30 (5) As mentioned above, as the values ​​Bx and Nz increase, the conductor shape deviates from the ideal shape, resulting in a deterioration in polarization characteristics. Therefore, for a conductor shape where Bx > 0, the sum of Bx and Dx is preferably 40% or less of the concave portion to ensure good polarization characteristics. On the other hand, for a conductor shape where Nz > 0, it is preferable to cover 30% or more of the height h of the convex portion to ensure good polarization characteristics.

[0052] More preferably, the numerical ranges of conditional expressions (4) and (5) are set as shown in the following conditional expressions (4a) and (5a), respectively.

[0053] (Bx + Dx) / (Pw)<0.398 (4a) (h-Nz) / h>0.31 (5a) More preferably, the numerical ranges of conditional expressions (4) and (5) are set as shown in the following conditional expressions (4b) and (5b), respectively.

[0054] (Bx + Dx) / (Pw)<0.395 (4b) (h-Nz) / h>0.32 (5b) In each example, the maximum open angle φ of the substrate 2 (curved surface) max It is preferable that the absolute value of [degrees] satisfies the following conditional expression (6).

[0055] 2≦|φ max |≦tan -1 (0.82h(Pw) / (0.3h 2 +0.6(Pw) 2 )) ···(6) By satisfying conditional expression (6), good polarization separation performance can be obtained by vapor deposition from a fixed angle twice, once on each side of the convex portion 3. Here, the opening angle φ is the angle between the surface normal (surface normal direction 7) at any location on the surface of the substrate 2 and the optical axis (optical axis direction). Maximum opening angle φ max is the largest open angle over the entire area of ​​the substrate 2 (transmissive reflecting element 100). Conditional expression (6) defines the range of the absolute value of the maximum open angle of the optical element within which the effects of each embodiment can be obtained. Maximum open angle φ max When the absolute value of is 2 degrees or less, the change in the shape of the conductor in the optical element is relatively small. Therefore, it is difficult to obtain an effect when comparing the amount of change in the polarization characteristics in the plane of the optical element of this example with that in the case of only one side surface of a conventional convex portion.

[0056] Also, the maximum opening angle φ maxBy making the absolute value of θ smaller than the upper limit of conditional expression (6), it is possible to obtain a conductor shape that satisfies conditional expressions (4) and (5). As mentioned above, the shape of a conductor formed by oblique evaporation from a fixed angle is determined by the incident angle of the evaporated material with respect to the convex portion. The incident angle θ that forms a conductor that satisfies the upper limit of conditional expression (4) is eq1 is expressed by the following equation (7).

[0057] θ eq1 =tan -1 (0.6(Pw) / h) (7) Similarly, the incident angle θ that forms the conductor is the lower limit value of conditional expression (5) eq2 is expressed by the following equation (8).

[0058] θ eq2 =tan -1 ((Pw) / 0.3h) ···(8) To obtain a conductor 4 that satisfies conditional expressions (4) and (5) over the entire surface of the transflective element 100, the incident angle of the deposition material to the convex portion 3 must be such that the two incident angles θ eq1 , θ eq2 Here, when a conductor is obtained by oblique deposition from a fixed angle on a substrate 2 having convex portions 3 on its curved surface, the angle of incidence of the deposition material with respect to the convex portions 3 is the opening angle of the substrate 2 having the convex portions 3. Therefore, by setting the opening angle of the substrate 2 to be equal to or less than the right-hand side of equation (6), which is the difference between equations (7) and (8), a transmission-reflection element with good polarization separation performance can be obtained.

[0059] If the thickness in the first direction of the conductor attached to the side surface of the convex portion and the thickness of the conductor in the region above the top surface of the convex portion are thin, polarization separation becomes difficult. Therefore, it is preferable that the sum of the thickness Dx1 of the first conductor 5 and the thickness Dx2 of the second conductor 6 is 8 nm or more (Dx1 + Dx2 ≧ 8). Furthermore, it is preferable that the thickness Dz (nm) in the surface normal direction 7 from the top of the convex portion 3 to the top of the conductor 4 is 10 nm or more (Dz ≧ 10). More preferably, these conditions are satisfied in all regions of the transflective element 100.

[0060] In each example, the thickness Ax and pitch P in the first direction of the conductors 4 in the region above the top surface of the largest convex portion 3 in the plane of the optical element satisfy the following conditional expression (9).

[0061] 0.25≦Ax / P≦0.55 (9) By satisfying conditional expression (9), even better polarization separation performance can be obtained. When the value of Ax / P, which is the ratio of the conductor to the pitch P defined by conditional expression (9), is close to the lower limit, the transmittance is high, making it possible to provide a high-transmittance transflective element. However, as the transmittance increases, the transmittance of unwanted light also increases. This reduces the polarization separation performance, making it difficult to obtain a high-contrast transflective element. On the other hand, when this value is large, the transmittance decreases, but the transmittance of S-polarized light is suppressed, resulting in excellent polarization separation function and a high-contrast transflective element. In this way, the characteristics of the transflective element can be controlled by the shape of the conductor depending on the intended use. In other words, the thickness Ax is the thickness in the first direction of the conductor 4 on the outer side in the third direction from the top surface (end surface) of each of the multiple convex portions 3.

[0062] Preferably, the numerical range of conditional expression (9) is set as in the following conditional expression (9a).

[0063] 0.27≦Ax / P≦0.54 (9a) More preferably, the numerical range of conditional expression (9) is set as in the following conditional expression (9b).

[0064] 0.29≦Ax / P≦0.53 (9b) Each example will be described in detail below. [Example]

[0065] First, a transmission-reflection element (optical element) 100 according to a first embodiment of the present invention will be described with reference to Fig. 4 and Fig. 5(a) and (b). Fig. 4 is a side view of the transmission-reflection element 100 according to this embodiment. Fig. 5 is a diagram showing the transmittance and reflectance according to this embodiment.

[0066] The transflective element 100 has a curved surface with a maximum open angle of 4 degrees and a flat back surface, and the curved surface side of the substrate is spherical, with thin conductor wires provided on the thin conductor wire surface 9 on the curved surface side.

[0067] The substrate 2 and the protrusions 3 are made of a cycloolefin copolymer. The protrusions have a periodic pitch P of 130 nm, a height h of 170 nm, and a width w in the first direction at half the height of 25 nm. The conductor 4 is made of aluminum, and the angle θ between the optical axis 8 and the deposition direction is 30 degrees. The conductor shapes shown in (a), (b), and (b') in Figure 4 were obtained by oblique deposition simulation on both sides of the protrusions. Note that the conductors are not scaled to scale and are deformed. In Figure 4, (a) shows the central portion of the transflective element 100, while (b) and (b') show the conductor shapes at both ends of the transflective element 100. The conductor shapes at both ends (b) and (b') are mirror images of each other. The thin conductor wires between the central portion and both ends are omitted, but the conductor shape changes continuously or stepwise depending on the incident angle of the deposition material on each protrusion.

[0068] The shapes of the first conductor 5 and the second conductor 6 include two shapes where Sz=0 and Bx=0, Sz>0 and Nz=0, and Sz>0 and Nz>0. It was confirmed in advance that the conductor shapes obtained by the deposition simulation closely matched the shapes of the conductors that were actually deposited.

[0069] The first conductor of the conductor (b) at the outermost end, or the second conductor of the conductor (b') at the other outermost end, has a conductor shape where Sz = 0 and Bx = 0, coated on the side of the convex portion so as to extend from the bottom of the concave portion of the uneven structure upward to the convex portion. Furthermore, Dx1 is 11.5 nm. The other side of the conductor, the second conductor of the conductor (b) at the outermost end, or the first conductor of the conductor (b') at the other outermost end, has a region of height Sz where the conductor coated on the side of the convex portion near the substrate is missing. In other words, a conductor shape where Sz > 0 and Nz = 0 is obtained. In this conductor shape, Nz is 0 nm, Sz is 24 nm, and Dx2 is 14 nm. In this conductor shape, Sz is at its maximum. Furthermore, Dz at the outermost end is 38.5 nm.

[0070] The first conductor 5 and second conductor 6 of the conductor (a) in the central portion are approximately symmetrical, and have a conductor shape where Sz>0 and Nz=0, with Dx1 and Dx2 being 10.5 nm, Nz being 0 nm, Sz being 22 nm, and Dz being 39 nm. The conductor shape between the central portion and the outermost end portion has a film thickness that increases or decreases stepwise or continuously.

[0071] In Figure 2, the shape of the conductor is shown schematically, so the surface is flat. However, when a conductor is vapor-deposited on a convex portion, scattered particles adhere and accumulate, resulting in a rough surface as shown in Figure 4. The thickness (average value) Ax in the first direction of the conductor above the top surface of the convex portion is 50.0 nm. These values ​​are average values, and in reality, they can be calculated from the average value of three adjacent shapes on any one cross section.

[0072] Figures 5(a) and (b) show the results of a rigorous coupled-wave analysis using the structure obtained by the oblique deposition simulation. Figure 5(a) shows the conductor shape at the center of the optical element shown in Figure 4(a), and Figure 5(b) shows the conductor shape at the edge of the optical element shown in Figure 4(b) and (b'). In Figures 5(a) and 5(b), the horizontal axis represents wavelength (nm), and the vertical axis represents transmittance (%) or reflectance (%). Tp (%) represents the transmittance of P-polarized light, Ts (%) represents the transmittance of S-polarized light, Rp (%) represents the reflectance of P-polarized light, and Rs (%) represents the reflectance of S-polarized light. Note that in Figure 5, because the value of transmittance Ts is small, only transmittance Ts is shown on the right vertical axis (second axis). These points also apply to figures showing the results of other examples. It has been confirmed in advance that the results of rigorous coupled-wave analysis of the polarization-selective semi-transmissive element obtained from the deposition simulation are in good agreement with the actual measured values ​​of the transmittance and reflectance for P-polarized and S-polarized light of the polarization-selective semi-transmissive element created by actual deposition at the same angle.

[0073] At a wavelength of 550 nm, where human visibility is high, the average polarization degree within the optical element plane is 99.9%, providing excellent polarization separation performance. The polarization degree can be calculated using the following equation (10).

[0074] [(Tp-Ts) / (Tp+Ts)]×100 ···(10) Furthermore, the maximum difference in Tp between the outermost and central conductors in the wavelength range of 400 nm to 700 nm is 2.26%pt. When this embodiment is applied to a head-mounted display or the like, it becomes possible to provide high-contrast images due to the high degree of polarization.

[0075] Below, we will show a comparative example of a polarization-selective semi-transmitting reflective element in which a conductor is formed only on one side of the convex portion by oblique vapor deposition from a fixed angle, rather than taking the conductor shape described in the present invention that covers the top and both side surfaces of the convex portion and at least a portion of the concave portion. (Comparative Example 1) Next, comparative example 1 for example 1 will be described with reference to Fig. 6 and Fig. 7(a) to (c). In this comparative example, similar to example 1, the curved surface of the substrate has a curved surface with a maximum open angle of 4 degrees and a flat back surface, and the curved surface side is spherical, with thin conductor wires provided on thin conductor wire surface 9 on the curved surface side.

[0076] The material forming the substrate 2 and the protrusions 3 is a cycloolefin copolymer, the protrusions have a periodic structure with a pitch P of 130 nm, a height h of 170 nm, and a width w in the third direction at half the height of 25 nm.

[0077] The material forming the conductor 4 is aluminum. Oblique deposition simulation from a deposition angle of 28 degrees on only one side of the convex portion yields three conductor shapes within the optical element surface: Sz = 0 and Bx = 0, Bx > 0, Sz > 0 and Nz = 0. Figure 6 is a side view of the transflective element 1000 of this comparative example. Figure 6(a) shows the conductor shape at the center of the optical element, Figure 6(b) shows the conductor shape at one end of the optical element, and Figure 6(c) shows the conductor shape at the other end of the optical element. Note that the conductor shapes are not drawn to scale and are deformed. The thin conductor wires between the center and both ends are omitted and not shown, but the conductor shape changes continuously or stepwise depending on the incident angle of the deposition material to each convex portion.

[0078] The conductor (a) in the center has a conductor shape such that Sz=0 and Bx=0, which is attached to the side surface of the convex portion so as to extend from the bottom of the concave portion of the uneven structure upward to the convex portion, and Dx is 23 nm and Dz is 41 nm.

[0079] For the conductor (b) at the other end, the angle of incidence of the deposition material incident on the convex portion is smaller than the deposition angle, resulting in a conductor shape where Bx > 0, with the conductor deposited in the concave portion being thicker than Dx. The conductor at the end has Dx 21 nm, Dz 39 nm, Bx 33 nm, and Bz 40 nm. This conductor shape maximizes Bx in the transflective element 100.

[0080] The conductor (c) at the other end has a larger incident angle of the deposition material incident on the protrusion than the deposition angle. As a result, the conductor deposited on the side of the protrusion near the substrate has a region of height Sz where it is missing, resulting in a conductor shape where Sz > 0 and Nz = 0. This conductor has Dx 28 nm, Dz 38 nm, Sz 46 nm, and Nz 0 nm.

[0081] The thickness of the conductor between the central portion and the outermost portion increases or decreases stepwise or continuously. The thickness (average value) Ax in the first direction of the conductor above the top surface of the convex portion is 49.0 nm.

[0082] Figures 7(a) to 7(c) show the results of rigorous coupled wave analysis. Figure 7(a) shows the conductor shape at the center of the optical element in Figure 6(a), Figure 7(b) shows the conductor shape at one end of the optical element in Figure 6(b), and Figure 7(c) shows the conductor shape at the other end of the optical element in Figure 6(c). The maximum difference in Tp between the conductors at the outermost and central portions at wavelengths of 400 nm to 700 nm is 4.56%pt, which is larger than Example 1 with the same opening angle. Even though the maximum opening angle is 4 degrees, which is a relatively gentle curve, forming the conductor by oblique deposition from a fixed angle on only one side of the convex portion results in significant changes in the conductor shape at the center and both ends, resulting in significant changes in the polarization characteristics within the optical element surface. The average polarization degree of the transflective element 100 at a wavelength of 550 nm is 99.9%. [Example]

[0083] Next, a transmission-reflection element (optical element) 100 according to a second embodiment of the present invention will be described with reference to Fig. 8 and Figs. 9(a) and (b). Fig. 8 is a side view of the transmission-reflection element 100 according to this embodiment. Fig. 9 is a diagram showing the transmittance and reflectance according to this embodiment.

[0084] The transflective element 100 has a curved surface with a maximum open angle of 33 degrees and a flat back surface, and the curved surface side of the substrate is spherical, with thin conductor wires provided on the thin conductor wire surface 9 on the curved surface side.

[0085] The material forming the substrate 2 and the convex portions 3 is a cycloolefin copolymer. The convex portions have a periodic structure with a pitch P of 130 nm, a height h of 170 nm, and a width w in the third direction at half the height of 25 nm. The material forming the conductor 4 is aluminum. The deposition angle θ, which is the angle between the optical axis 8 and the deposition direction, is 44.5 degrees. The conductor shapes shown in Figures 8(a), (b), and (b') are obtained by oblique deposition simulation on both sides of the convex portions. Figure 8(a) shows the conductor shape at the center of the optical element, while Figures 8(b) and (b') show the conductor shapes at both ends of the optical element. The conductor shapes at both ends (b) and (b') are mirror images of each other. The conductor shapes are not drawn to scale and are deformed.

[0086] The shapes of the first and second conductors are Sz=0 and Bx=0, Sz>0 and Nz=0, and Sz>0 and Nz>0. The first and second conductors in the central conductor (a) are approximately symmetrical. The first and second conductors have conductor shapes where Sz>0 and Nz>0, with Dx1 and Dx2 being 19.5 nm, Nz being 60 nm, Sz being 88.5 nm, and Dz being 42 nm.

[0087] The first conductor of the conductor (b) at one end or the second conductor of the conductor (b') at the other end has a conductor shape where Sz=0 and Bx=0, and a conductor shape with Dx1 of 11.5 nm is obtained. Furthermore, the second conductor of the conductor (b) at the end, which is the other side of the conductor, or the first conductor of the conductor (b') at the other end, has a conductor shape where Sz>0 and Nz>0, with Nz being 111.8 nm, Sz being 11.7 nm, and Dx2 being 21 nm. This conductor shape has the largest Sz in the transflective element 100. Dz at the end is 32.1 nm.

[0088] The thickness of each of the conductor shapes between the central portion and the outermost end increases or decreases stepwise or continuously, and a conductor shape is formed in the region between the central portion and the end portions such that Sz > 0 and Nz = 0. The thickness (average value) Ax in the first direction of the conductor above the top surface of the convex portion is 60.8 nm.

[0089] Figures 9(a) and (b) show the results of a rigorous coupled-wave analysis using the above structure obtained through oblique deposition simulation. Figure 9(a) shows the results of a rigorous coupled-wave analysis of the center portion, and Figure 9(b) shows the results of a rigorous coupled-wave analysis of both ends. The maximum difference in Tp between the outermost and central conductors at wavelengths from 400 nm to 700 nm is 9.1%pt, and despite the curved surface having a maximum opening angle of 33 degrees, the change in polarization characteristics within the optical element plane is reduced. The average degree of polarization within the optical element plane at a wavelength of 550 nm is 99.9%. (Comparative Example 2) Next, comparative example 2 will be described in relation to example 2. In this comparative example, similar to example 2, the curved surface of the substrate has a curved surface with a maximum open angle of 33 degrees and a flat back surface, and the curved surface side is spherical, with thin conductor wires provided on the thin conductor wire surface 9 on the curved surface side. Fig. 10 is a side view of a transflective element 1000a in this comparative example. The material forming the substrate 2 and the protrusions 3 is a cycloolefin copolymer, the protrusions have a periodic structure with a pitch P of 130 nm, a height h of 170 nm, and a width w in the third direction at half the height of 25 nm.

[0090] The material forming the conductor 4 is aluminum, and in a simulation of oblique deposition from a deposition angle of 44.5 degrees on only one side of the convex portion, three conductor shapes were obtained: Sz = 0 and Bx = 0, Sz > 0 and Nz = 0, and Sz > 0 and Nz > 0. Figure 10(a) shows the conductor shape at one end, and Figure 10(b) shows the conductor shape at the other end. The thin conductor wire between the two ends is omitted and not shown, but the conductor shape changes continuously or stepwise depending on the incident angle of the deposition material to each convex portion.

[0091] The conductor shape at one end of the optical element is such that Sz=0 and Bx=0, with Dx being 23 nm and Dz being 41 nm. The conductor shape at the other end is such that Sz>0 and Nz>0, with Dx being 42 nm, Dz being 23.3 nm, Sz being 135.1 nm, and Nz being 111.8 nm. The film thickness, Sz, and Nz of the conductor shape between both ends decrease or increase stepwise or continuously, forming a conductor shape in which Sz>0 and Nz=0 in the region between both ends.

[0092] In the transflective element 1000a, the thickness (average value) Ax in the first direction of the conductor above the top surfaces of the convex portions is 57.5 nm.

[0093] Figure 11(a) shows the results of a rigorous coupled-wave analysis of the conductor shape at the other end (Figure 10(a)), and Figure 11(b) shows the conductor shape at the other end (Figure 10(b)). The maximum difference in transmittance Tp between the conductor at the outermost and central portions at wavelengths from 400 nm to 700 nm is 18.9%pt. Because the maximum open angle is 33 degrees, which is a relatively sharp curve, forming the conductor by oblique evaporation from a fixed angle on only one side of the convex portion results in significant changes in the conductor shape at both ends, resulting in significant changes in the polarization characteristics of the optical element. The average polarization degree within the optical element surface at a wavelength of 550 nm is 97.9%. [Example]

[0094] Next, a transmission-reflection element (optical element) 100 according to a third embodiment of the present invention will be described with reference to Fig. 12 and Figs. 13(a) and (b). Fig. 12 is a side view of the transmission-reflection element 100 according to this embodiment. Figs. 13(a) and (b) are diagrams showing the transmittance and reflectance according to this embodiment. Fig. 12 shows a deformed side view of the transmission-reflection element 100, which is not to the actual scale of this embodiment.

[0095] The transflective element 100 has a curved surface with a maximum open angle of 12 degrees and a flat back surface, and the curved surface side of the substrate is spherical, with thin conductor wires provided on the thin conductor wire surface 9 on the curved surface side.

[0096] The material forming the substrate 2 and the convex portions 3 is a cycloolefin copolymer, and the convex portions have a periodic structure with a pitch P of 130 nm, a height h of 170 nm, and a width w in the third direction at half the height of 25 nm. The material forming the conductor 4 is aluminum, and the conductor shapes shown in Figures 12(a), (b), and (b') are obtained by oblique deposition simulation on both side surfaces of the convex portions with a deposition angle θ, which is the angle between the optical axis 8 and the deposition direction, of 31 degrees. Figure 12(a) shows the conductor shape in the center of the optical element, and Figures 12(b) and (b') show the conductor shapes at both ends of the optical element, with the conductor shapes at both ends (b) and (b') being mirror images of each other.

[0097] In the transflective element 100, the shapes of the first and second conductors are such that Bx>0, Sz=0 and Bx=0, Sz>0 and Nz=0, and Sz>0 and Nz>0, respectively.

[0098] The first and second conductors in the central portion are approximately symmetrical, resulting in a conductor shape where Sz > 0 and Nz = 0. The first and second conductors have Dx1 and Dx2 of 14 nm, Nz of 0 nm, Sz of 23 nm, and Dz of 38 nm.

[0099] The first conductor of the conductor (b) at one end or the second conductor of the conductor (b') at the other end has a conductor shape such that Bx>0, with Dx1 being 13 nm, Bx being 20 nm, and Bz being 20 nm. Furthermore, the second conductor at the end, or the first conductor at the other end, which is another side of the conductor, has a conductor shape such that Sz>0 and Nz>0, with Sz being 61.5 nm, Nz being 29 nm, and Dx2 being 16 nm. Dz at the end is 38 nm.

[0100] The thickness of each of the conductor shapes between the central portion and the outermost end increases or decreases stepwise or continuously, and the first conductor shape and the second conductor shape are formed such that Sz = 0 and Bx = 0 in the regions between the central portion and the end. The thickness (average thickness) Ax in the first direction of the conductor above the top surface of the convex portion is 52.8 nm.

[0101] Figure 13(a) shows the results of rigorous coupled-wave analysis using the above structure obtained by oblique deposition simulation for the center portion, and Figure 13(b) shows the results for the edge portion. The maximum difference in transmittance Tp between the conductors at the edge and center portions in the wavelength range of 400 nm to 700 nm is 11.5%pt. For light with a wavelength of 550 nm, the average polarization degree in the transflective element 100 is 99.9%. [Example]

[0102] Next, a transmission-reflection element (optical element) 100 according to a fourth embodiment of the present invention will be described with reference to Fig. 14 and Figs. 15(a) and (b). Fig. 14 is a side view of the transmission-reflection element 100 according to this embodiment. Figs. 15(a) and (b) are diagrams showing the transmittance and reflectance according to this embodiment. Fig. 14 shows a deformed side view of the transmission-reflection element 100, which is not to the actual scale of this embodiment.

[0103] The transflective element 100 is a curved substrate with a maximum opening angle of 12 degrees, and its back surface is a curved substrate with a maximum opening angle of 6 degrees. The curved surface side having the convex portion is spherical, and the curved surface side is provided with a thin conductor wire on the thin conductor wire surface 9.

[0104] The material forming the substrate 2 and the protrusions 3 is a cycloolefin copolymer, and the protrusions have a periodic structure with a pitch P of 130 nm, a height h of 170 nm, and a width w in the third direction at half the height of 25 nm. The material forming the conductor 4 is aluminum, and the conductor shapes shown in Figure 14(a), (b), and (b') are obtained by oblique deposition simulation on both sides of the protrusions with a deposition angle θ, which is the angle between the optical axis 8 and the deposition direction, of 34 degrees. The shapes of the first and second conductors obtained are three: Sz = 0 and Bx = 0, Sz > 0 and Nz = 0, and Sz > 0 and Nz > 0.

[0105] The first and second conductors of the conductor (a) in the central portion are approximately symmetrical, resulting in a conductor shape where Sz > 0 and Nz > 0. The first and second conductors have Dx1 and Dx2 of 15 nm, Nz of 15 nm, Sz of 53 nm, and Dz of 37 nm.

[0106] The first conductor of the conductor (b) at the outermost end, or the second conductor of the conductor (b') at the other outermost end, has a conductor shape where Bx=0 and Sz=0, and Dx1 is 13 nm. Furthermore, the other side of the conductor, the second conductor of the conductor (b) at the outermost end, or the first conductor of the conductor (b') at the other outermost end, has a conductor shape where Sz>0 and Nz>0, with Sz being 74 nm, Nz being 43 nm, and Dx2 being 16.5 nm. Dz at the outermost end is 38 nm.

[0107] The thickness of each of the conductor shapes between the central portion and the outermost end increases or decreases stepwise or continuously, and first and second conductor shapes are formed in the regions between the central portion and the end such that Sz > 0 and Nz = 0. The thickness (average value) Ax in the first direction of the conductor above the top surface of the convex portion is 54.8 nm.

[0108] Using the above structure obtained by oblique deposition simulation, the results of rigorous coupled wave analysis are shown in Figure 15(a) for the center portion and in Figure 15(b) for the edge portion. The maximum difference in transmittance Tp between the conductors at the edge and center portions in the wavelength range of 400 nm to 700 nm was 3.6%pt. For light with a wavelength of 550 nm, the average polarization degree in the transflective element 100 was 99.9%. [Example]

[0109] Next, a transmission-reflection element (optical element) 100 according to a fifth embodiment of the present invention will be described with reference to Fig. 16 and Figs. 17(a) and (b). Fig. 16 is a side view of the transmission-reflection element 100 according to this embodiment. Figs. 17(a) and (b) are diagrams showing the transmittance and reflectance according to this embodiment. Fig. 16 shows a deformed side view of the transmission-reflection element 100, which is not to the actual scale of this embodiment.

[0110] The transflective element 100 has a curved surface with a maximum open angle of 6 degrees and a flat back surface, and the curved surface side of the substrate is spherical, with thin conductor wires provided on the thin conductor wire surface 9 on the curved surface side.

[0111] The material forming the substrate 2 and the protrusions 3 is a cycloolefin copolymer, and the protrusions have a periodic structure with a pitch P of 80 nm, a height h of 60 nm, and a width w in the third direction at half the height of 15 nm. The material forming the conductor 4 is aluminum, and the conductor shapes shown in Figure 16(a), (b), and (b') are obtained by oblique deposition simulation on both sides of the protrusions with a deposition angle θ of 50.3 degrees, which is the angle between the optical axis 8 and the deposition direction. Three conductor shapes are obtained for the first and second conductors: Sz = 0 and Bx = 0, Sz > 0 and Nz = 0, and Sz > 0 and Nz > 0.

[0112] The first and second conductors of the conductor (a) in the central portion are approximately symmetrical, resulting in a conductor shape where Sz > 0 and Nz > 0. The first and second conductors have Dx1 and Dx2 of 13.5 nm, Nz of 6.1 nm, Sz of 17.2 nm, and Dz of 22.4 nm.

[0113] The first conductor of the conductor (b) at the outermost end, or the second conductor of the conductor (b') at the other outermost end, has a conductor shape where Bx=0 and Sz=0, and Dx1 is 12.9 nm. The other side of the conductor, the second conductor at the outermost end, or the first conductor at the other outermost end, has a conductor shape where Sz>0 and Nz>0, with Sz being 22 nm, Nz being 11.6 nm, and Dx2 being 14 nm. Dz at the outermost end is 22.5 nm.

[0114] The thickness of each of the conductor shapes between the central portion and the outermost end increases or decreases stepwise or continuously, and the first conductor shape and the second conductor shape are formed in the regions between the central portion and the end such that Sz > 0 and Nz = 0. The thickness (average value) Ax in the first direction of the conductor above the top surface of the convex portion is 42.0 nm.

[0115] Using the above structure obtained by the oblique deposition simulation, the results of rigorous coupled wave analysis of the center portion are shown in FIG. 17(a) and the edge portion in FIG. 17(b).

[0116] In this embodiment, the height of the convex portions is relatively low at 60 nm, which tends to increase the transmittance Ts. However, the value of Ax / P, which is the ratio of conductors to the pitch P expressed by conditional formula (9), is close to the upper limit. A small value of this value allows for a low transmittance Ts, resulting in good polarization separation performance in this embodiment. The maximum difference in transmittance Tp between the conductors at the outermost and central portions for light with wavelengths from 400 nm to 700 nm is 2.3%pt. Because the transmittance Tp decreases around 600 nm, a bluish image is output when applied to a head-mounted display, etc. However, the difference in transmittance Tp in the transflective element 100 is small, and the wavelength characteristics are uniform. Therefore, a good output image can be obtained by adjusting the luminance value of the light source panel of the head-mounted display after 600 nm to cancel out the wavelength characteristics of the transflective element 100. The average polarization degree of the transflective element 100 for light with a wavelength of 550 nm is 98.9%. [Example]

[0117] Next, a transmission-reflection element (optical element) 100 according to a sixth embodiment of the present invention will be described with reference to Fig. 18 and Figs. 19(a) and (b). Fig. 18 is a side view of the transmission-reflection element 100 according to this embodiment. Figs. 19(a) and (b) are diagrams showing the transmittance and reflectance according to this embodiment. Fig. 18 shows a deformed side view of the transmission-reflection element 100, which is not to the actual scale of this embodiment.

[0118] The transflective element 100 has a curved surface with a maximum open angle of -20 degrees and a flat back surface, and the curved surface side of the substrate is spherical, with thin conductor wires provided on the thin conductor wire surface 9 on the curved surface side.

[0119] The material forming the substrate 2 and the protrusions 3 is a cycloolefin copolymer, and the protrusions have a periodic structure with a pitch P of 150 nm, a height h of 250 nm, and a width w in the third direction at half the height of 35 nm. The material forming the conductor 4 is aluminum, and the conductor shapes shown in Figure 18(a), (b), and (b') are obtained by oblique deposition simulation on both sides of the protrusions with a deposition angle θ, which is the angle between the optical axis 8 and the deposition direction, of 32 degrees. The shapes of the first and second conductors obtained are three: Sz = 0 and Bx = 0, Sz > 0 and Nz = 0, and Sz > 0 and Nz > 0.

[0120] The first and second conductors of the conductor (a) in the central portion are approximately symmetrical, resulting in a conductor shape where Sz > 0 and Nz > 0. The first and second conductors have Dx1 and Dx2 of 5.3 nm, Nz of 66 nm, Sz of 74.5 nm, and Dz of 16.9 nm.

[0121] The first conductor of the conductor (b) at the outermost end, or the second conductor of the conductor (b') at the other outermost end, has a conductor shape where Sz>0 and Nz>0, with Sz being 129.7 nm, Nz being 122.3 nm, and Dx2 being 6.7 nm. The other side of the conductor, the second conductor at the outermost end, or the first conductor at the other outermost end, has a conductor shape where Bx=0 and Sz=0, with Dx1 being 3.7 nm. Dz at the outermost end is 16.7 nm.

[0122] The thickness of the conductor shape between the central portion and the outermost end increases or decreases stepwise or continuously, and the first conductor shape and the second conductor shape are formed in the region between the central portion and the end such that Sz > 0 and Nz = 0. The thickness (average value) Ax in the first direction of the conductor above the top surface of the convex portion is 45.5 nm.

[0123] Using the above structure obtained by oblique deposition simulation, the results of rigorous coupled wave analysis are shown in Figure 19(a) for the center portion and in Figure 19(b) for the edge portion. The maximum difference in transmittance Tp between the conductors at the edge and center portions for light with wavelengths of 400 nm to 700 nm is 4.3%pt. The average polarization degree of the transflective element 100 for light with a wavelength of 550 nm is 97.0%.

[0124] In this embodiment, the value of Ax / P expressed by conditional expression (9) is close to the lower limit side. If this value is small, the transmittance of S-polarized light becomes high, but good transmittance can be obtained. [Example]

[0125] Next, a transmission-reflection element (optical element) 100 according to a seventh embodiment of the present invention will be described with reference to Fig. 20 and Figs. 21(a) and (b). Fig. 20 is a side view of the transmission-reflection element 100 according to this embodiment. Figs. 21(a) and (b) are diagrams showing the transmittance and reflectance according to this embodiment. Fig. 20 shows a deformed side view of the transmission-reflection element 100, which is not to the actual scale of this embodiment.

[0126] The transflective element 100 is a substrate having a curved surface with a maximum open angle of 38 degrees and a flat rear surface, the curved surface being spherical, and having thin conductor wires on the thin conductor wire surface 9 on the curved surface side.

[0127] The material forming the substrate 2 and the protrusions 3 is a cycloolefin copolymer, and the protrusions have a periodic structure with a pitch P of 120 nm, a height h of 150 nm, and a width w in the third direction at half the height of 20 nm. The material forming the conductor 4 is aluminum, and the conductor shapes shown in Figure 20(a), (b), and (b') are obtained by oblique deposition simulation on both sides of the protrusions when the deposition angle θ, which is the angle between the optical axis 8 and the deposition direction, is 44 degrees. The shapes of the first and second conductors obtained are four: Bx>0, Sz=0 and Bx=0, Sz>0 and Nz=0, and Sz>0 and Nz>0.

[0128] The first and second conductors of the conductor (a) in the central portion are approximately symmetrical, resulting in a conductor shape where Sz > 0 and Nz > 0. The first and second conductors have Dx1 and Dx2 of 13.4 nm, Nz of 46.5 nm, Sz of 60.8 nm, and Dz of 28.8 nm.

[0129] The first conductor of the conductor (b) at the outermost end, or the second conductor of the conductor (b') at the other outermost end, has a conductor shape such that Bx>0, with Dx1 being 8.5 nm, Bx=30 nm, and Bz=18.1 nm. Furthermore, the other side of the conductor, the second conductor of the conductor (b) at the outermost end, or the first conductor of the conductor (b') at the other outermost end, has a conductor shape such that Sz>0 and Nz>0, with Sz being 108 nm, Nz being 98 nm, and Dx2 being 17.8 nm. Dz at the outermost end is 27.2 nm.

[0130] The thickness of the conductor shape between the central portion and the outermost end increases or decreases stepwise or continuously, and a first conductor shape and a second conductor shape are formed in the region between the central portion and the end such that Sz = 0 and Nz = 0, and Sz > 0 and Nz = 0. The thickness (average value) Ax in the first direction of the conductor above the top surface of the convex portion is 46.6 nm.

[0131] Using the above structure obtained by oblique deposition simulation, the results of rigorous coupled wave analysis are shown in Figure 21(a) for the center portion and in Figure 21(b) for the edge portion. The maximum difference in transmittance Tp between the conductors at the edge and center portions for light with wavelengths of 400 nm to 700 nm is 17.9%pt, and this difference varies within the transflective element 100. However, at wavelengths of 450 nm to 650 nm, where visibility is high, the maximum difference in transmittance Tp is 8.6%pt, resulting in good polarization characteristics within the transflective element 100. In addition, the transmittance of P-polarized light for light with wavelengths of 450 nm to 650 nm is also high, resulting in a transflective element 100 with high transmittance. The average polarization degree of the transflective element 100 for light with a wavelength of 550 nm is 99.9%.

[0132] The values ​​of each conditional expression in each example are summarized in Table 1. Here, the left side of conditional expression (4) represents the largest value for each conductor shape, and the left side of conditional expression (5) represents the smallest value for the thin conductor wire. Furthermore, Ax in conditional expression (9) is the average value within the transflective element 100.

[0133] [Table 1] [Example]

[0134] Next, an optical system (optical device) 200 according to an eighth embodiment of the present invention will be described with reference to FIG. 22. FIG. 22 is a cross-sectional view of the optical system 200. The optical system 200 includes optical elements G1, G2, G3, and G4, and a display device D. The optical element G1 is a refractive optical element. The optical element G2 is a cemented element including a transflective element 100 having a thin metal wire formed on the thin conductor wire surface 9 of each of the above-described embodiments, a first quarter-wave plate 11, and a refractive optical element 12 having a half mirror 13 on its surface. The optical element G3 is a second quarter-wave plate. The optical element G4 is a polarizing plate. The display device D is an image display element such as a liquid crystal display element or an organic EL element.

[0135] Light emitted from display device D is converted into linearly polarized light by optical element G4, converted into circularly polarized light by optical element G3, and then enters half mirror 13. A portion of the light that enters half mirror 13 is reflected and becomes reverse circularly polarized light, and returns to optical element G3. The reverse circularly polarized light that has returned to optical element G3 is converted by optical element G3 into linearly polarized light having a polarization direction perpendicular to the polarization direction when it passed through the initial optical element G4, returns to optical element G4, and is absorbed by optical element G4.

[0136] On the other hand, the remainder of the light incident on the half mirror 13 is transmitted through it and converted by the first quarter-wave plate 11 into linearly polarized light in the same polarization direction as when it passed through optical element G4, and then incident on the transmissive reflecting element 100. This linearly polarized light is reflected by the polarization selectivity of the transmissive reflecting element 100. The light reflected by the transmissive reflecting element 100 is converted by the first quarter-wave plate 11 into circularly polarized light in the opposite direction to when it was first converted into circularly polarized light by optical element G3, and then incident on the half mirror 13, where it is reflected.

[0137] The light reflected by the half mirror 13 becomes circularly polarized light in the opposite direction to the light before reflection and enters the first quarter-wave plate 11. It is then converted into linearly polarized light having a polarization direction perpendicular to the polarization direction when it first passed through the optical element G4 and enters the transmissive reflector 100. This linearly polarized light passes through the transmissive reflector 100 due to its polarization selectivity and is guided to the eye 10. The image displayed on the display device D is magnified and observed by a refractive optical element with power arranged in the optical path of the optical system 200. [Example]

[0138] Next, a head mounted display (observation device, optical device) 300 according to a ninth embodiment of the present invention will be described with reference to Fig. 23 and Fig. 24. Fig. 23 is a cross-sectional view of the head mounted display 300. Fig. 23 is an external view of the head mounted display 300.

[0139] The head mounted display 300 has optical systems 201 and 202. The optical systems 201 and 202 have the same lens configuration, and are, for example, the optical system 200 of Example 8. In Fig. 23, 14 denotes a human right eye, and 15 denotes a human left eye. The optical systems 201 and 202 are housed in a goggle-type case 18 and are positioned relative to the right eye 14 and left eye 15, respectively.

[0140] The head-mounted display 300 is worn on the observer's head when in use. The observer sees an enlarged image on the display devices 16 and 17 through the optical systems 201 and 202. Different images with parallax are projected onto the display devices 16 and 17, allowing the observer to see a stereoscopic image.

[0141] The optical elements of each embodiment are obtained by oblique deposition from a fixed angle without using special mechanisms such as masks or oscillations, and can reduce changes in the conductor shape and polarization characteristics without requiring a process for removing unnecessary portions. Therefore, each embodiment can provide optical elements and optical devices that are easy to manufacture and have uniform optical performance.

[0142] The disclosure of each embodiment includes the following configuration. (Configuration 1) A substrate having a curved surface; a plurality of convex portions arranged on the curved surface along a first direction; a conductor provided on each of the plurality of protrusions, each of the plurality of protrusions extends in a second direction perpendicular to the first direction and protrudes in a third direction perpendicular to both the first direction and the second direction; each of the plurality of protrusions has an end face in the third direction and a first side face and a second side face disposed on both sides of the end face in the first direction; In a cross section including the first direction and the third direction, the conductor covers at least a part of the end face of each of the plurality of protrusions, at least a part of the first side surface, and at least a part of the second side surface; When the arrangement pitch of the plurality of protrusions is P (nm), and the thickness of each of the plurality of protrusions in the first direction of the conductor on the outer side of the end face in the third direction is Ax (nm), 0.25≦Ax / P≦0.55 An optical element characterized by satisfying the following conditional expression: (Configuration 2) In the cross section, the height of the convex portion in the third direction is h (nm), the width of the convex portion in the first direction at half the height of the convex portion is w (nm), and the maximum open angle of the curved surface is φ max When expressed in degrees, 2≦|φ max |≦tan -1 (0.82h(Pw) / (0.3h 2 +0.6(Pw) 2 )) 2. The optical element according to configuration 1, wherein the following condition is satisfied: (Configuration 3) the conductor has a first conductor provided on the first side surface and a second conductor provided on the second side surface, 3. The optical element according to claim 1, wherein the first conductor and the second conductor have asymmetric shapes with respect to an axis in the third direction that passes through the center of the convex portion. (Configuration 4) the conductor has a first conductor provided on the first side surface and a second conductor provided on the second side surface, When the thicknesses of the first conductor and the second conductor at the top of the convex portion in the first direction are Dx1 (nm) and Dx2 (nm), respectively, The thickness Dx1 increases in a direction away from one end of the optical element, 4. The optical element according to any one of configurations 1 to 3, wherein the thickness Dx2 decreases in a direction away from one end of the optical element. (Configuration 5) When the thickness in the third direction from the top of the convex portion to the top of the conductor is Dz (nm), Dz≧10 5. The optical element according to any one of configurations 1 to 4, wherein the following condition is satisfied: (Configuration 6) the conductor has a first conductor provided on the first side surface and a second conductor provided on the second side surface, When the thicknesses of the first conductor and the second conductor at the top of the convex portion in the first direction are Dx1 (nm) and Dx2 (nm), respectively, Dx1+Dx2≧8 6. The optical element according to any one of configurations 1 to 5, wherein the following condition is satisfied: (Configuration 7) the conductor has a first conductor provided on the first side surface and a second conductor provided on the second side surface, In the cross section, with respect to each of the first conductor and the second conductor, when a value obtained by subtracting the thickness in the first direction of the conductor deposited on the side surface at the top of the convex portion from the maximum thickness in the first direction of the conductor deposited on the side surface of the convex portion is denoted as Bx (nm), a height in the third direction of a region where the conductor deposited on the side surface of the convex portion is missing is denoted as Sz (nm), and a height in the third direction of a region where no film is formed on the side surface of the convex portion is denoted as Nz (nm), at least two of Bx>0, or Bx=0 and Sz=0, or Sz>0 and Nz=0, are satisfied; 7. The optical element according to any one of configurations 1 to 6, wherein the value Bx, the height Sz, and the height Nz change continuously or stepwise in the cross section. (Configuration 8) When the height of the convex portion in the third direction in the cross section is h (nm), 50≦h≦300 8. The optical element according to any one of configurations 1 to 7, wherein the following condition is satisfied: (Configuration 9) 9. The optical element according to any one of configurations 1 to 8, wherein the base material and the plurality of convex portions are integrally configured. (Configuration 10) 70≦P≦170 10. The optical element according to any one of configurations 1 to 9, wherein the following condition is satisfied: (Configuration 11) In the cross section, when the width in the first direction of the convex portion at half the height of the convex portion is w (nm), the thickness in the first direction of the conductor attached to the side surface at the top of the convex portion is Dx (nm), and the value obtained by subtracting the thickness Dx from the maximum thickness in the first direction of the conductor attached to the side surface of the convex portion is Bx (nm), (Bx+Dx) / (Pw)<0.40 11. The optical element according to any one of configurations 1 to 10, wherein the following condition is satisfied: (Configuration 12) In the cross section, when the height of the convex portion in the third direction is h (nm), and the height of the conductor in the third direction of a region where the conductor is not formed on the side surface of the convex portion is Nz (nm), (h-Nz) / h>0.30 12. The optical element according to any one of configurations 1 to 11, wherein the following condition is satisfied: (Configuration 13) the substrate has a curved surface; 13. The optical element according to any one of configurations 1 to 12, wherein the plurality of convex portions are formed on the curved surface. (Configuration 14) 14. An optical device comprising a plurality of optical elements including the optical element according to any one of configurations 1 to 13.

[0143] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0144] 2 Base material 2a curved surface 3 Convex part 4 Conductors 100 Transmissive / reflective element (optical element)

Claims

1. A substrate having a curved surface; a plurality of convex portions arranged on the curved surface along a first direction; a conductor provided on each of the plurality of protrusions, each of the plurality of protrusions extends in a second direction perpendicular to the first direction and protrudes in a third direction perpendicular to both the first direction and the second direction; each of the plurality of protrusions has an end surface in the third direction and a first side surface and a second side surface disposed on both sides of the end surface in the first direction; In a cross section including the first direction and the third direction, the conductor covers at least a part of the end face of each of the plurality of protrusions, at least a part of the first side surface, and at least a part of the second side surface; When the arrangement pitch of the plurality of protrusions is P (nm), and the thickness of each of the plurality of protrusions in the first direction of the conductor on the outer side of the end face in the third direction is Ax (nm), 0.25≦Ax / P≦0.55 An optical element characterized by satisfying the following conditional expression:

2. In the cross section, the height of the convex portion in the third direction is h (nm), the width of the convex portion in the first direction at half the height of the convex portion is w (nm), and the maximum open angle of the curved surface is φ ｍａｘ When expressed as [degrees], 2≦|φ ｍａｘ |≦tan －１ (0.82h(P-w) / (0.3h ２ +0.6(P-w) ２ )) 2. The optical element according to claim 1, wherein the following condition is satisfied:

3. the conductor has a first conductor provided on the first side surface and a second conductor provided on the second side surface, 3. The optical element according to claim 1, wherein the first conductor and the second conductor have asymmetric shapes with respect to an axis in the third direction that passes through the center of the convex portion.

4. the conductor has a first conductor provided on the first side surface and a second conductor provided on the second side surface, When the thicknesses of the first conductor and the second conductor at the top of the convex portion in the first direction are Dx1 (nm) and Dx2 (nm), respectively, The thickness Dx1 increases in a direction away from one end of the optical element, 3. The optical element according to claim 1, wherein the thickness Dx2 decreases in a direction away from the one end of the optical element.

5. When the thickness in the third direction from the top of the convex portion to the top of the conductor is Dz (nm), Dz≧10 3. The optical element according to claim 1, wherein the following condition is satisfied:

6. the conductor has a first conductor provided on the first side surface and a second conductor provided on the second side surface, When the thicknesses of the first conductor and the second conductor at the top of the convex portion in the first direction are Dx1 (nm) and Dx2 (nm), respectively, Dx1 + Dx2 ≧ 8 3. The optical element according to claim 1, wherein the following condition is satisfied:

7. the conductor has a first conductor provided on the first side surface and a second conductor provided on the second side surface, In the cross section, with respect to each of the first conductor and the second conductor, when a value obtained by subtracting the thickness in the first direction of the conductor deposited on the side surface at the top of the convex portion from the maximum thickness in the first direction of the conductor deposited on the side surface of the convex portion is Bx (nm), a height in the third direction of a region where the conductor deposited on the side surface of the convex portion is missing is Sz (nm), and a height in the third direction of a region where no film is formed on the side surface of the convex portion is Nz (nm), at least two of Bx>0, or Bx=0 and Sz=0, or Sz>0 and Nz=0, are satisfied; 3. The optical element according to claim 1, wherein the value Bx, the height Sz, and the height Nz change continuously or stepwise in the cross section.

8. When the height of the convex portion in the third direction in the cross section is h (nm), 50≦h≦300 3. The optical element according to claim 1, wherein the following condition is satisfied:

9. 3. The optical element according to claim 1, wherein the base material and the plurality of convex portions are integrally formed.

10. 70≦P≦170 3. The optical element according to claim 1, wherein the following condition is satisfied:

11. In the cross section, when the width in the first direction of the convex portion at half the height of the convex portion is w (nm), the thickness in the first direction of the conductor attached to the side surface at the top of the convex portion is Dx (nm), and the value obtained by subtracting the thickness Dx from the maximum thickness in the first direction of the conductor attached to the side surface of the convex portion is Bx (nm), (Bx+Dx) / (P-w)<0.40 3. The optical element according to claim 1, wherein the following condition is satisfied:

12. In the cross section, when the height of the convex portion in the third direction is h (nm), and the height of a region of the conductor where the conductor is not formed on the side surface of the convex portion in the third direction is Nz (nm), (h-Nz) / h>0.30 3. The optical element according to claim 1, wherein the following condition is satisfied:

13. the substrate has a curved surface; 3. The optical element according to claim 1, wherein the plurality of convex portions are formed on the curved surface.

14. An optical device comprising a plurality of optical elements including the optical element according to claim 1 or 2.

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