Polarization element, manufacturing method of polarization element, and optical apparatus

Abstract

To provide a polarization element capable of improving the transmission axis transmittance even when the variation in the incident angles of light is large.SOLUTION: A polarization element 10 comprises: a transparent substrate 11; and a lattice-shaped protrusions 12 arranged on one face of the transparent substrate 11 at a pitch shorter than a wavelength of light in a use band and extending in a prescribed direction. The lattice-shaped protrusions 12 include a reflection layer 21 and an absorption layer 22 in order from the transparent substrate 11 side. A width of the absorption layer 22 is substantially the same as a width of the side facing the absorption layer 22, of the reflection layer 21. In a cross section viewed from a direction in which the lattice-shaped protrusions 12 extend, A central plane C2 passing through a center in a width direction of the absorption layer 22 is spaced by a prescribed interval from a central plane C1 passing through a center in a width direction of the reflection layer 21.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a polarizing element, a method for manufacturing a polarizing element, and an optical device. [Background technology]

[0002] A polarizing element is an optical element that absorbs polarized light in a specific direction and transmits polarized light perpendicular to the direction of the absorbed polarized light. Liquid crystal display devices, in principle, require polarizing elements. In particular, polarizing elements used in liquid crystal display devices that use a light source with a large amount of light, such as an LCD projector, are exposed to strong radiation, so they must be heat-resistant, be several centimeters in size, and have a high extinction ratio and controllable reflectance characteristics. To meet these requirements, wire-grid polarizing elements have been proposed.

[0003] A wire-grid polarizing element includes a transparent substrate and lattice-shaped protrusions arranged on one surface of the transparent substrate at a pitch shorter than the wavelength of light in the used band and extending in a predetermined direction (see, for example, Patent Document 1). When light is incident on the polarizing element, s-polarized light (TE waves (s waves)) having an electric field component parallel to the extension direction of the lattice-shaped protrusions cannot be transmitted, but p-polarized light (TM waves (p waves)) having an electric field component perpendicular to the extension direction of the lattice-shaped protrusions is transmitted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-64326 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the wire grid type polarizing element, if there is a large variation in the incident angle of light, the transmission axis transmittance may decrease.

[0006] An object of the present invention is to provide a polarizing element that can improve the transmission axis transmittance even when the incident angle of light varies greatly. [Means for solving the problem]

[0007] (1) A polarizing element comprising: a transparent substrate; and lattice-shaped convex portions arranged on one surface of the transparent substrate at a pitch shorter than the wavelength of light in a used band and extending in a predetermined direction, the lattice-shaped convex portions having, in order from the transparent substrate side, a reflective layer and an absorbing layer, the width of the absorbing layer being approximately the same as the width of the side of the reflective layer facing the absorbing layer, and when viewed in cross section from the direction in which the lattice-shaped convex portions extend, a central plane passing through the center of the width direction of the absorbing layer is separated by a predetermined distance from a central plane passing through the center of the width direction of the reflective layer.

[0008] (2) The polarizing element described in (1), wherein, when viewed in cross section from the direction in which the grid-shaped convex portions extend, the ratio of the width of the region on one side of a central plane passing through the center of the width direction of the reflective layer to the width of the region on the other side of a central plane passing through the center of the width direction of the reflective layer is 0 or more and 45 / 55 or less.

[0009] (3) A polarizing element according to (2), wherein when the light in the used band is blue light, the width ratio is 25 / 75 or more and 40 / 60 or less, when the light in the used band is green light, the width ratio is 0 or more and 45 / 55 or less, when the light in the used band is red light, the width ratio is 35 / 65 or more and 45 / 55 or less, and when the light in the used band is visible light, the width ratio is 25 / 75 or more and 45 / 55 or less.

[0010] (4) The polarizing element according to any one of (1) to (3), wherein the transparent substrate comprises glass, crystal, quartz, or sapphire.

[0011] (5) The polarizing element according to any one of (1) to (4), wherein the absorption layer contains a metal material or a semiconductor material.

[0012] (6) The polarizing element according to any one of (1) to (5), further comprising an anti-reflection layer on the other surface of the transparent substrate.

[0013] (7) A polarizing element according to any one of (1) to (6), wherein at least a portion of the surface is covered with a protective film, and the protective film contains Si oxide, Ti oxide, Zr oxide, Al oxide, Nb oxide, or Ta oxide.

[0014] (8) The polarizing element according to any one of (1) to (7), wherein at least a portion of the surface is covered with an organic water-repellent film.

[0015] (9) A method for producing a polarizing element according to any one of (1) to (8), comprising the steps of: forming a reflective layer on one surface of the transparent substrate; selectively etching the reflective layer to form precursors of the grid-shaped convex portions; patterning a resist in areas of the one surface of the transparent substrate where the precursors of the grid-shaped convex portions are not formed; forming an absorbing layer on the surfaces of the precursors of the grid-shaped convex portions and the resist; and selectively etching the absorbing layer to form the grid-shaped convex portions.

[0016] (10) The method for producing a polarizing element according to (9), further comprising the step of forming an antireflection layer on the other surface of the transparent substrate.

[0017] (11) A method for producing a polarizing element according to (9) or (10), further comprising the step of covering at least a portion of the surface with a protective film, the protective film containing Si oxide, Ti oxide, Zr oxide, Al oxide, Nb oxide or Ta oxide.

[0018] (12) The method for producing a polarizing element according to any one of (9) to (11), further comprising the step of covering at least a part of the surface with an organic water-repellent film.

[0019] (13) An optical device comprising the polarizing element according to any one of (1) to (8). [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a polarizing element capable of improving the transmission axis transmittance even when the incident angle of light varies greatly. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic perspective view showing a polarizing element according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing the polarizing element of FIG. [Figure 3] 2 is a cross-sectional view schematically illustrating a modified example of the polarizing element of FIG. 1. FIG. [Figure 4] 2 is a cross-sectional view schematically illustrating a modified example of the polarizing element of FIG. 1. FIG. [Figure 5] 2A to 2C are cross-sectional views illustrating a method for manufacturing the polarizing element of FIG. [Figure 6] 2A to 2C are cross-sectional views illustrating a method for manufacturing the polarizing element of FIG. [Figure 7] 2A to 2C are cross-sectional views illustrating a method for manufacturing the polarizing element of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0023] [Polarizing element] 1 and 2 show a polarizing element according to one embodiment of the present invention.

[0024] The polarizing element 10 comprises a transparent substrate 11 and lattice-shaped convex portions 12, each having a width w and a height h, arranged on one surface of the transparent substrate 11 at a pitch p shorter than the wavelength of light in the band of light used, extending in the Y-axis direction.

[0025] 1 and 2, the direction in which the grid-shaped protrusions 12 extend is referred to as the Y-axis direction. Furthermore, the direction perpendicular to the Y-axis direction and in which the grid-shaped protrusions 12 are arranged at pitch p along the main surface of the transparent substrate 11 is referred to as the X-axis direction. Furthermore, the direction perpendicular to the Y-axis direction and the X-axis direction, i.e., the direction perpendicular to the main surface of the transparent substrate 11, is referred to as the Z-axis direction. Note that the direction in which light enters the polarizing element 10 is the Z-axis direction, but it is preferable that light enter from the side of the polarizing element 10 on which the grid-shaped protrusions 12 are formed.

[0026] Polarizing element 10 utilizes four functions: transmission, reflection, interference, and selective absorption of polarized light due to optical anisotropy, to attenuate s-polarized light (TE waves (s waves)) having an electric field component parallel to the Y-axis direction and transmit p-polarized light (TM waves (p waves)) having an electric field component parallel to the X-axis direction. Therefore, the Y-axis direction is the direction of the absorption axis of polarizing element 10, and the X-axis direction is the direction of the transmission axis of polarizing element 10.

[0027] Here, the height h of the grid-shaped protrusions 12 refers to the dimension in the Z-axis direction perpendicular to the main surface of the transparent substrate 11. The width w of the grid-shaped protrusions 12 refers to the dimension in the X-axis direction of the grid-shaped protrusions 12. Furthermore, the pitch p of the grid-shaped protrusions 12 refers to the repeating interval in the X-axis direction of the polarizing element 10.

[0028] The pitch p of the grid-shaped convex portions 12 is not particularly limited as long as it is shorter than the wavelength of light in the band used, but from the viewpoint of ease of manufacturing and stability of the polarizing element 10, it is preferably 100 nm or more and 200 nm or less. The pitch p of the grid-shaped convex portions 12 can be measured by observation with a scanning electron microscope or a transmission electron microscope. The pitch p of the grid-shaped convex portions 12 is, for example, the arithmetic mean value of measurements taken at any four locations. Hereinafter, this measurement method will be referred to as the electron microscopy method.

[0029] As shown in FIG. 2, the grid-shaped protrusions 12 have, in order from the transparent substrate 11 side, a reflective layer 21 and an absorbing layer 22. Here, the grid-shaped protrusions 12 have a wire grid structure arranged in a one-dimensional lattice pattern. The reflective layer 21 and the absorbing layer 22 are rectangular in cross section, and the width of the absorbing layer 22 is approximately the same as the width of the side of the reflective layer 21 facing the absorbing layer 22. Furthermore, when viewed cross-sectionally from the direction in which the grid-shaped protrusions 12 extend, a central plane C2 passing through the center of the width direction of the absorbing layer 22 is spaced a predetermined distance from a central plane C1 passing through the center of the width direction of the reflective layer 21. Therefore, even if there is a large variation in the incident angle θ of light, the transmission axis transmittance is improved. In this case, the ratio (w1 / w2) of the width w2 of the region of the absorbing layer 22 that is on one side (the right side in the drawing) of the central plane C1 that passes through the center in the width direction of the reflective layer 21 to the width w1 of the region that is on the other side (the left side in the drawing) of the central plane C1 that passes through the center in the width direction of the reflective layer 21 is preferably 0 or more and 45 / 55 or less. When w1 / w2 is 0 or more and 45 / 55 or less, the transmission axis transmittance is further improved even if the incident angle θ of light varies greatly.

[0030] For example, when the light in the used band is blue light, w1 / w2 is preferably 25 / 75 or more and 40 / 60 or less, with 25 / 75 being particularly preferred. Furthermore, when the light in the used band is green light, w1 / w2 is preferably 0 or more and 45 / 55 or less, with 25 / 75 being particularly preferred. Furthermore, when the light in the used band is red light, w1 / w2 is preferably 35 / 65 or more and 45 / 55 or less, with 35 / 65 being particularly preferred. Furthermore, when the light in the used band is visible light, w1 / w2 is preferably 25 / 75 or more and 45 / 55 or less, with 25 / 75 being particularly preferred.

[0031] A portion of the light incident from the side of the transparent substrate 11 on which the grid-shaped convex portions 12 are formed is absorbed and attenuated as it passes through the absorption layer 22. Of the light that has passed through the absorption layer 22, p-polarized light (TM light (p-wave)) passes through the reflective layer 21 with high transmittance. On the other hand, of the light that has passed through the absorption layer 22, s-polarized light (TE light (s-wave)) is reflected by the reflective layer 21. The s-polarized light reflected by the reflective layer 21 is partially absorbed as it passes through the absorption layer 22, but is also partially reflected and returns to the reflective layer 21. Furthermore, the s-polarized light reflected by the reflective layer 21 interferes and is attenuated as it passes through the absorption layer 22. As described above, the s-polarized light is selectively attenuated, allowing the polarizing element 10 to obtain desired polarization characteristics.

[0032] (Transparent substrate) The material for the transparent substrate 11 is not particularly limited as long as it is transparent to light in the usable band, and can be appropriately selected depending on the purpose. Examples of light in the usable band include visible light with a wavelength of 400 nm or more and 700 nm or less.

[0033] Note that "transparent to light in the used band" means that the transmittance of light is sufficient to maintain the function as a polarizing element, and does not mean that the transmittance of light in the used band is 100%.

[0034] The transparent substrate 11 is preferably made of a material having a refractive index of 1.1 or more and 2.2 or less. Materials having a refractive index of 1.1 or more and 2.2 or less are not particularly limited, but examples thereof include glass, crystal, quartz, and sapphire. Among these, quartz and glass are preferred from the viewpoints of cost and light transmittance, and quartz with a refractive index of 1.46 and soda-lime glass with a refractive index of 1.51 are particularly preferred. Furthermore, crystal and sapphire are preferred from the viewpoint of thermal conductivity. This improves the heat resistance of the transparent substrate 11, allowing it to be used in liquid crystal projectors.

[0035] When an optically active crystal such as quartz or sapphire is used as the material for the transparent substrate 11, it is preferable to arrange the lattice-shaped convex portions 12 in a direction parallel to or perpendicular to the optical axis of the crystal. This results in excellent optical properties. Here, the optical axis is the directional axis along which the difference in refractive index between the O (ordinary ray) and E (extraordinary ray) of light traveling in that direction is minimum.

[0036] The average thickness of the transparent substrate 11 is not particularly limited, but is, for example, 0.3 mm or more and 1 mm or less. The shape of the main surface of the transparent substrate 11 is not particularly limited, but may be, for example, a rectangular shape.

[0037] (reflective layer) The reflective layer 21 is formed on one surface of the transparent substrate 11 and forms grid-shaped convex portions 12 extending in the Y-axis direction. The reflective layer 21 attenuates s-polarized light (TE waves (s waves)) having an electric field component in the Y-axis direction and transmits p-polarized light (TM waves (p waves)) having an electric field component in the X-axis direction.

[0038] The thickness of the reflective layer 21 is not particularly limited, but is, for example, 100 nm or more and 300 nm or less. The thickness of the reflective layer 21 is measured, for example, by electron microscopy.

[0039] The material constituting the reflective layer 21 is not particularly limited as long as it is capable of reflecting light in the used band, but examples include simple elements such as Al, Ag, Cu, Mo, Cr, Ti, Nd, Ni, W, Fe, Si, Ge, and Te, and alloys containing one or more of these elements. Among these, aluminum or an aluminum alloy is preferable. Note that the reflective layer 21 may also be, for example, a non-metallic inorganic film or a resin film whose surface reflectance has been increased by coloring.

[0040] The method for forming the reflective layer 21 is not particularly limited, but examples thereof include vapor deposition and sputtering.

[0041] The reflective layer 21 may be a laminate in which layers made of different constituent materials are stacked.

[0042] (Absorption layer) The absorbing layer 22 is formed on the surface of the reflecting layer 21 and forms grid-shaped convex portions 12 extending in the Y-axis direction.

[0043] The thickness of the absorbing layer 22 is not particularly limited, but is, for example, 5 nm to 50 nm, and is measured by, for example, an electron microscope method.

[0044] The material constituting the absorption layer 22 is not particularly limited as long as it can absorb light in the used band, and examples thereof include metal materials and semiconductor materials. Examples of metal materials include simple elements such as Ta, Al, Ag, Cu, Au, Mo, Cr, Ti, W, Ni, Fe, and Sn, and alloys containing one or more of these elements. Examples of semiconductor materials include Si, Ge, Te, ZnO, and silicide materials (β-FeSi2, MgSi2, NiSi2, BaSi2, CrSi2, CoSi2, TaSi, etc.). Among these, materials containing Fe or Ta as well as Si are preferred.

[0045] When a semiconductor material is used as the material for composing the absorption layer 22, it is necessary to use a semiconductor material whose band gap energy is equal to or less than the energy of light in the used band. For example, when the light in the used band is visible light, it is necessary to use a semiconductor material whose band gap energy is equal to or less than the energy of light with a wavelength of 400 nm, i.e., 3.1 eV or less.

[0046] The method for forming the absorbing layer 22 is not particularly limited, but examples thereof include vapor deposition and sputtering.

[0047] The absorbent layer 22 may be a laminate in which layers made of different materials are stacked.

[0048] (Anti-reflection layer) The polarizing element 10 may have an antireflection layer on the other surface of the transparent substrate 11. The antireflection layer is, for example, a laminate in which low-refractive index layers and high-refractive index layers having different refractive indices are alternately stacked.

[0049] The material for forming the antireflection layer is not particularly limited, but examples thereof include Si oxide, Ti oxide, Zr oxide, Al oxide, Nb oxide, and Ta oxide.

[0050] The thickness of the antireflection layer is not particularly limited, but is, for example, 1 nm to 500 nm The thickness of the antireflection layer is measured, for example, by electron microscopy.

[0051] The method for forming the antireflection layer is not particularly limited, but examples thereof include vapor deposition, sputtering, CVD (Chemical Vapor Deposition), and ALD (Atomic Layer Deposition). Among these, ion-beam assisted deposition (IAD) and ion beam sputtering (IBS) are preferred.

[0052] (protective film) At least a part of the surface of the polarizing element 10 may be covered with a protective film, which improves the durability of the polarizing element 10.

[0053] The material constituting the protective film is the same as the material constituting the anti-reflection layer.

[0054] The method for forming the protective film is not particularly limited, but examples thereof include the CVD method and the ALD method.

[0055] The protective film may be a laminate in which layers made of different materials are stacked.

[0056] (organic water-repellent film) At least a part of the surface of the polarizing element 10 may be covered with an organic water-repellent film, which improves the moisture resistance of the polarizing element 10.

[0057] The material for forming the organic water-repellent film is not particularly limited, but examples thereof include fluorine-based silane coupling agents such as tridecafluorooctyltrichlorosilane (FOTS).

[0058] The method for forming the organic water-repellent film is not particularly limited, but examples thereof include the CVD method, the ALD method, and the coating method.

[0059] (simulation) Simulations were conducted to verify that the transmission axis transmittance of the polarizing element 10 improves even when the light incident angle θ varies greatly. Specifically, simulations were performed using Gsolver (manufactured by Grating Solver Development) under the following conditions. Next, the average values ​​of the transmission axis transmittance were calculated when the light incident angles were -45°, -30°, -15°, 0°, 15°, 30°, and 45°. Refractive index of transparent substrate 11: 1.5 Width of the reflective layer 21 and the absorbing layer 22: 28 nm Height of the reflective layer 21: 250 nm Material constituting the reflective layer 21: Al Height of the absorption layer 22: 35 nm Material constituting the absorption layer 22: FeSi w1 / w2:50 / 50, 45 / 55, 40 / 60, 35 / 65, 25 / 75, 0 Blue light wavelength range: 430-510nm Green light wavelength range: 520-590nm Red light wavelength range: 600-680nm Visible light wavelength range: 400-700nm Light incident angle: -45°, -30°, -15°, 0°, 15°, 30°, 45°

[0060] Table 1 shows the evaluation results of the average transmission axis transmittance.

[0061] [Table 1]

[0062] Table 1 shows that when the incident angle of visible light is 0°±45°, the transmission axis transmittance is improved when w1 / w2 is 25 / 75 or more and 45 / 55 or less than when w1 / w2 is 50 / 50. Furthermore, when the incident angle of blue light is 0°±45°, the transmission axis transmittance is improved when w1 / w2 is 25 / 75 or more and 40 / 60 or less than when w1 / w2 is 50 / 50. Furthermore, when the incident angle of green light is 0°±45°, the transmission axis transmittance is improved when w1 / w2 is 0 or more and 45 / 55 or less than when w1 / w2 is 50 / 50. Furthermore, when the incident angle of red light is 0°±45°, the transmission axis transmittance is improved when w1 / w2 is 35 / 65 or more and 45 / 55 than when w1 / w2 is 50 / 50.

[0063] The cross-sectional shape of the reflective layer 21 is not particularly limited as long as the width of the side of the reflective layer 21 facing the absorption layer 22 is approximately the same as the width of the absorption layer 22. The cross-sectional shape of the reflective layer 21 may be, for example, a trapezoidal shape whose width continuously increases or decreases (see FIGS. 3(a) and (b)), or a hexagonal shape whose width continuously decreases and then increases (see FIG. 3(c)).

[0064] Furthermore, the grid-shaped convex portion 12 is not particularly limited as long as it has, in this order from the transparent substrate 11 side, a reflective layer 21 and an absorbing layer 22. For example, the grid-shaped convex portion 12 may further have an absorbing layer 22 between the transparent substrate 11 and the reflective layer 21 (see FIG. 4(a)). In this case, the absorbing layers 22 arranged on both sides of the reflective layer 21 are arranged line-symmetrically with respect to a central plane C3 passing through the center of the reflective layer 21 in the height direction. In this case, the grid-shaped convex portion 12 may further have an intermediate layer 41 between the reflective layer 21 and the absorbing layer 22 (see FIG. 4(b)). In this case, the intermediate layers 41 arranged on both sides of the reflective layer 21 are arranged line-symmetrically with respect to a central plane C3 passing through the center of the reflective layer 21 in the height direction. Furthermore, the distance between the central plane passing through the center in the width direction of the intermediate layer 41 and the central plane passing through the center in the width direction of the reflective layer 21 is approximately the same as the distance between the central plane passing through the center in the width direction of the absorbing layer 22 and the central plane passing through the center in the width direction of the reflective layer 21, but the absorbing layer 22 and the intermediate layer 41 are arranged on opposite sides in the width direction with respect to the central plane C1 passing through the center in the width direction of the reflective layer 21. The intermediate layer 41 is not particularly limited, and examples thereof include an absorbing layer, a reflective layer, and an anti-reflection layer.

[0065] [Method of manufacturing polarizing element] A method for manufacturing the polarizing element 10 will be described with reference to FIGS.

[0066] First, a reflective layer 21 is formed on one surface of the transparent substrate 11 (see FIG. 5(a)), and then a resist R1 is patterned on the surface of the reflective layer 21 (see FIG. 5(b)). Next, the reflective layer 21 is selectively etched (see FIG. 5(c)), and then the resist R1 is removed to form precursors 12A of the grid-shaped convex portions (see FIG. 6(a)). Next, a resist R2 is patterned in the areas of one surface of the transparent substrate 11 where the precursors 12A of the grid-shaped convex portions are not formed (see FIG. 6(b)). Then, an absorbing layer 22 is formed on the surfaces of the precursors 12A of the grid-shaped convex portions and the resist R2 (see FIG. 6(c)). Next, a resist R3 is patterned on the surface of the absorbing layer 22 (see FIG. 7(a)), and then the absorbing layer 22 is selectively etched (see FIG. 7(b)). Finally, the resists R2 and R3 are removed to form the grid-shaped convex portions 12, and the polarizing element 10 is obtained (see FIG. 7(c)).

[0067] The resist pattern formation method is not particularly limited, but examples thereof include photolithography and nanoimprinting. The etching method is not particularly limited, but examples thereof include dry etching using an etching gas corresponding to the etching target.

[0068] An anti-reflection layer may be formed on the other surface of the transparent substrate 11. Also, at least a part of the surface may be covered with a protective film, or at least a part of the surface may be covered with an organic water-repellent film.

[0069] [Optical equipment] The polarizing element 10 can be applied to optical devices such as liquid crystal displays, liquid crystal projectors, head-up displays, car headlights, etc. Among these, in consideration of the heat resistance of the polarizing element 10, liquid crystal projectors are preferred.

[0070] In addition, when an optical device includes a plurality of polarizing elements, at least one of the plurality of polarizing elements may be polarizing element 10. For example, in a liquid crystal projector, at least one of the polarizing elements arranged on the entrance side and exit side of a liquid crystal panel may be polarizing element 10.

[0071] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described embodiments may be modified as appropriate within the scope of the spirit of the present invention. [Explanation of symbols]

[0072] 10 Polarizing element 11 Transparent substrate 12 Lattice-shaped convex part 12A Precursor of lattice-shaped convex part 21 Reflective layer 22 Absorbing layer 41 Middle Class C1, C2, C3 center plane R1, R2, R3 Resist

Claims

1. a transparent substrate; and lattice-shaped convex portions arranged on one surface of the transparent substrate at a pitch shorter than the wavelength of light in a used band and extending in a predetermined direction; the grid-shaped convex portion has, in order from the transparent substrate side, a reflective layer and an absorbing layer, a width of the absorption layer is approximately the same as a width of the side of the reflection layer facing the absorption layer; A polarizing element, wherein, when viewed in cross section from the direction in which the grid-shaped convex portions extend, a central plane passing through the center in the width direction of the absorption layer is spaced a predetermined distance from a central plane passing through the center in the width direction of the reflective layer.

2. 2. The polarizing element according to claim 1, wherein, when viewed in cross section from a direction in which the grid-shaped convex portions extend, the ratio of the width of a region present on one side of a central plane passing through the center of the width direction of the reflective layer to the width of a region present on the other side of the central plane passing through the center of the width direction of the reflective layer is 0 or more and 45 / 55 or less.

3. When the light in the used band is blue light, the ratio of the widths is 25 / 75 or more and 40 / 60 or less; When the light in the used band is green light, the ratio of the widths is 0 to 45 / 55, When the light in the used band is red light, the ratio of the widths is 35 / 65 or more and 45 / 55 or less; The polarizing element according to claim 2 , wherein the ratio of the widths is 25 / 75 or more and 45 / 55 or less when the light in the used band is visible light.

4. 4. The polarizing element according to claim 1, wherein the transparent substrate comprises glass, crystal, quartz, or sapphire.

5. The polarizing element according to claim 1 , wherein the absorbing layer comprises a metallic material or a semiconductor material.

6. The polarizing element according to claim 1 , further comprising an anti-reflection layer on the other surface of the transparent substrate.

7. At least a portion of the surface is covered with a protective film, The polarizing element according to claim 1 , wherein the protective film contains Si oxide, Ti oxide, Zr oxide, Al oxide, Nb oxide, or Ta oxide.

8. The polarizing element according to claim 1 , wherein at least a part of the surface is covered with an organic water-repellent film.

9. A method for producing the polarizing element according to any one of claims 1 to 3, comprising the steps of: forming a reflective layer on one surface of the transparent substrate; a step of selectively etching the reflective layer to form precursors of the grid-shaped convex portions; forming a resist pattern on an area of ​​one surface of the transparent substrate where no precursor of the grid-shaped convex portions is formed; forming an absorption layer on the surface of the precursor of the grid-shaped convex portion and the resist; and forming the grid-shaped convex portions by selectively etching the absorption layer.

10. The method for producing a polarizing element according to claim 9 , further comprising the step of forming an anti-reflection layer on the other surface of the transparent substrate.

11. further comprising the step of coating at least a portion of the surface with a protective film; The method for manufacturing a polarizing element according to claim 9 , wherein the protective film contains Si oxide, Ti oxide, Zr oxide, Al oxide, Nb oxide, or Ta oxide.

12. The method for producing a polarizing element according to claim 9 , further comprising the step of covering at least a part of the surface with an organic water-repellent film.

13. An optical instrument comprising the polarizing element according to any one of claims 1 to 3.

Images