Polarizing element, method for manufacturing polarizing element, and optical apparatus

Abstract

The invention provides a polarizing element, a method for manufacturing the polarizing element, and an optical apparatus. The polarizing element can give consideration to oil resistance and heat resistance of a waterproof film. A polarizing element (10) is provided with a transparent substrate (11) and lattice-shaped protrusions (12) which are arranged on one surface of the transparent substrate (11) at a pitch shorter than the wavelength of light in a use wavelength band and which extend in a predetermined direction. The lattice-shaped protrusion (12) has a reflective layer (21), a dielectric layer (22), and an absorbing layer (23) in this order from the transparent substrate (11) side. In the polarizing element (10), a waterproof film (25) is formed on the surface of the lattice-shaped protrusions (12) and on the surface of the transparent substrate (11) on the side on which the lattice-shaped protrusions (12) are arranged, wherein regions treated with a first waterproof treatment agent (25a) and regions treated with a second waterproof treatment agent (25b) are non-uniformly present.

Description

Technical Field

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

[0002] In recent years, inorganic polarizing elements have been used to replace organic polarizing elements in optical devices such as liquid crystal projectors that require heat resistance. Among inorganic polarizing elements, wire grid-type polarizing elements with lattice-shaped protrusions (which have a reflective layer, a dielectric layer, and an absorption layer in sequence from the transparent substrate side) are widely used in liquid crystal projectors due to their high heat resistance. The lattice-shaped protrusions are arranged on one surface of the transparent substrate at a pitch shorter than the wavelength of the light in the use band and extend in a specified direction. The lattice-shaped protrusions are formed, for example, by forming a reflective layer, a dielectric layer, and an absorption layer using a physical film forming method, and then selectively etching them using a photolithography method and a dry etching method.

[0003] On the other hand, to prevent deterioration of optical properties and appearance quality due to stains caused by moisture and dust in the atmosphere, polarizing elements are formed with a waterproof film covering the surface of the lattice-shaped protrusions. In addition to water repellency, the waterproof film is also required to have oil repellency.

[0004] Patent Document 1 describes forming protective films on the surfaces of the lattice-shaped protrusions and the bottom surfaces of the grooves formed between the lattice-shaped protrusions. The protective films include a first protective film formed to cover the surface of the reflective layer, a second protective film formed of an organic film to cover the bottom surfaces of the grooves, and a third protective film formed of an organic film to cover the surface of the absorption layer.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-64326 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] Here, in liquid crystal projector applications, heat resistance is required for the waterproof film, but it is difficult to achieve both oil repellency and heat resistance of the waterproof film.

[0010] An object of the present invention is to provide a polarizing element capable of achieving both oil repellency and heat resistance of a waterproof film.

[0011] Methods for solving problems

[0012] (1) A polarizing element comprising a transparent substrate and lattice-shaped projections, wherein the lattice-shaped projections are arranged on one surface of the transparent substrate at a pitch shorter than the wavelength of light in a used wavelength band and extend in a predetermined direction, wherein the lattice-shaped projections have a reflective layer, a dielectric layer, and an absorption layer in that order from the transparent substrate side, and a waterproof film is formed on the surface of the lattice-shaped projections and the surface of the transparent substrate on the side where the lattice-shaped projections are arranged, wherein the waterproof film has regions treated with a plurality of different waterproofing agents unevenly.

[0013] (2) The polarizing element according to (1), wherein the plurality of different water repellents include a first water repellent containing a perfluoroalkyl group and a second water repellent not containing a perfluoroalkyl group.

[0014] (3) The polarizing element according to (2), wherein the first water repellent is trichloro(1H,1H,2H,2H-perfluoro-n-octyl)silane, and the second water repellent is dimethyldichlorosilane.

[0015] (4) A method for manufacturing a polarizing element, which is a method for manufacturing the polarizing element described in any one of (1) to (3), comprising the steps of forming a laminate by stacking a reflective layer, a dielectric layer, and an absorption layer in sequence from the transparent substrate side on one surface of the transparent substrate, forming the grid-shaped protrusions by selectively etching the laminate, and forming the waterproof film by treating the surface of the grid-shaped protrusions and the surface of the transparent substrate on the side where the grid-shaped protrusions are formed with the plurality of different waterproofing agents.

[0016] (5) The method for manufacturing a polarizing element according to (4), wherein the waterproof film is formed by alternately treating the surface of the lattice-shaped protrusions and a portion of the surface of the transparent substrate on the side where the lattice-shaped protrusions are formed with the plurality of different waterproofing agents.

[0017] (6) An optical device comprising the polarizing element according to any one of (1) to (3).

[0018] Effects of the Invention

[0019] According to the present invention, a polarizing element can be provided that can achieve both oil repellency and heat resistance of a water repellent film. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a perspective schematic diagram showing a polarizing element according to one embodiment of the present invention.

[0021] Figure 2 Yes Figure 1 Schematic cross-sectional view of a polarizing element.

[0022] Figure 3 This is a graph showing the relationship between the treatment amount of FOTS in Comparative Example 1 and the contact angle with water.

[0023] Figure 4 This is a graph showing the relationship between the treatment amount of DDMS in Comparative Example 2 and the contact angle with respect to water.

[0024] Figure 5 This is a schematic diagram for explaining the method for evaluating the oil repellency of the waterproof membrane in Examples.

[0025] Figure 6 This is a graph showing the evaluation results of the oil repellency of the water repellent films of the polarizing elements of Example 1, Comparative Example 1, and Comparative Example 2.

[0026] Figure 7 This is a graph showing the evaluation results of the heat resistance of the waterproof films of the polarizing elements of Example 1, Comparative Example 1, and Comparative Example 2.

[0027] Description of Reference Numerals

[0028] 10: Polarizing element, 11: Transparent substrate, 12: Lattice-shaped convex portion, 13: Antireflection layer, 21: Reflection layer, 22: Dielectric layer, 23: Absorption layer, 24, 26: Protective films, 25: Waterproof film, 25a: First water-repellent treatment agent, 25b: Second water-repellent treatment agent. DETAILED DESCRIPTION

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0030] [Polarizing element]

[0031] Figure 1 A polarizing element according to one embodiment of the present invention is shown.

[0032] Polarizing element 10 includes transparent substrate 11 and lattice-shaped projections 12 arranged on one surface of transparent substrate 11 at a pitch shorter than the wavelength of light in the operating wavelength band and extending in a predetermined direction. Polarizing element 10 also includes antireflection layer 13 on the other surface of transparent substrate 11.

[0033] Here, the direction in which the lattice-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 lattice-shaped protrusions 12 are arranged along the principal 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, that is, the direction perpendicular to the principal surface of the transparent substrate 11, is referred to as the Z-axis direction. It should be noted that the direction in which light enters the polarizing element 10 is the Z-axis direction, and preferably, light enters from the side of the polarizing element 10 where the lattice-shaped protrusions 12 are formed.

[0034] The polarizing element 10 utilizes four effects: transmission, reflection, interference, and selective absorption of polarized waves due to optical anisotropy. This attenuates polarized waves with an electric field component parallel to the Y-axis (TE waves (S waves)) and transmits polarized waves with an electric field component parallel to the X-axis (TM waves (P waves)). Therefore, the Y-axis direction is the absorption axis of the polarizing element 10, and the X-axis direction is the transmission axis of the polarizing element 10.

[0035] like Figure 2 As shown, the lattice-shaped protrusions 12 have a reflective layer 21, a dielectric layer 22, and an absorption layer 23 in order from the transparent substrate 11 side. Here, the lattice-shaped protrusions 12 have a wire grid structure arranged in a one-dimensional lattice. In addition, the surface of the lattice-shaped protrusions 12 of the polarizing element 10 and the surface of the side of the transparent substrate 11 on which the lattice-shaped protrusions 12 are arranged are covered with a protective film 24. As a result, the heat resistance of the polarizing element 10 is improved. In addition, the polarizing element 10 has a waterproof film 25 formed on the surface of the protective film 24, and the waterproof film 25 has an area treated with a first waterproof treatment agent 25a and an area treated with a second waterproof treatment agent 25b unevenly. Therefore, the oil repellency and heat resistance of the waterproof film 25 are taken into account. In addition, the polarizing element 10 has an anti-reflection layer 13 and a protective film 26 on the other side of the transparent substrate 11 in order from the transparent substrate 11 side.

[0036] The first water repellent agent 25a is not particularly limited as long as it can improve the oil repellency of the waterproof membrane 25. Examples include perfluoroalkyl-containing silane coupling agents such as trichloro(1H,1H,2H,2H-perfluoro-n-octyl)silane, and two or more thereof may be used in combination. The number of carbon atoms in the perfluoroalkyl group of the first silane coupling agent is not particularly limited, but may be, for example, 4 to 8. The number of hydrolyzable groups in the first silane coupling agent is not particularly limited, but may be, for example, 2 to 3. The hydrolyzable group is not particularly limited, but may include, for example, a chloro group, an alkoxy group, and a hydrogen group.

[0037] The second water repellent agent 25b is not particularly limited as long as it can improve the heat resistance of the waterproof membrane 25. Examples include silane coupling agents that do not contain a perfluoroalkyl group, such as dimethyldichlorosilane. Two or more silane coupling agents may be used in combination. The number of carbon atoms in the alkyl group of the second silane coupling agent is not particularly limited, but may be, for example, 2 to 12. The number of hydrolyzable groups in the second silane coupling agent is not particularly limited, but may be, for example, 2 to 3. The hydrolyzable group is not particularly limited, but may include, for example, a chloro group, an alkoxy group, and a hydrogen group.

[0038] The method for forming the waterproof film 25 is not particularly limited, and examples thereof include a CVD (Chemical Vapor Deposition) method, an ALD (Atomic Layer Deposition) method, and a coating method.

[0039] It should be noted that the polarizing element 10 may omit at least one of the anti-reflection layer 13 , the protective film 24 , and the protective film 26 as needed.

[0040] Light incident from the side of the polarizing element 10 where the lattice-shaped protrusions 12 are formed is partially absorbed and attenuated when passing through the absorption layer 23 and the dielectric layer 22. The polarized waves (TM waves (P waves)) in the light that passes through the absorption layer 23 and the dielectric layer 22 pass through the reflective layer 21 with high transmittance. On the other hand, the polarized waves (TE waves (S waves)) in the light that passes through the absorption layer 23 and the dielectric layer 22 are reflected by the reflective layer 21. The TE waves reflected by the reflective layer 21 are partially absorbed when passing through the dielectric layer 22 and the absorption layer 23, but are partially reflected and return to the reflective layer 21. In addition, the TE waves reflected by the reflective layer 21 interfere and attenuate when passing through the dielectric layer 22 and the absorption layer 23. As described above, by selectively attenuating the TE waves, the polarizing element 10 can obtain the desired polarization characteristics.

[0041] Here, use Figure 2 The dimensions of the lattice-shaped protrusions 12 are described below. The height h of the lattice-shaped protrusions 12 refers to the dimension of the lattice-shaped protrusions 12 in the Z-axis direction. The width w of the lattice-shaped protrusions 12 refers to the dimension of the lattice-shaped protrusions 12 in the X-axis direction. Furthermore, the pitch p of the lattice-shaped protrusions 12 refers to the repetitive spacing of the lattice-shaped protrusions 12 in the X-axis direction.

[0042] The pitch p of the lattice-shaped protrusions 12 is not particularly limited as long as it is shorter than the wavelength of light in the operating band. From the perspective of ease of manufacture and stability of the polarizing element 10, it is preferably greater than 100 nm and less than 200 nm. It should be noted that the pitch p of the lattice-shaped protrusions 12 can be measured by observation with a scanning electron microscope or a transmission electron microscope. The pitch p of the lattice-shaped protrusions 12 is, for example, the arithmetic mean of the measured values ​​at any four locations. Hereinafter, such a measurement method will be referred to as an electron microscopy method.

[0043] (Transparent substrate)

[0044] The transparent substrate 11 is not particularly limited as long as it is transparent to light in the wavelength range used, and can be appropriately selected according to the purpose. The light in the wavelength range used is not particularly limited, and examples thereof include visible light with a wavelength of 400 nm to 700 nm.

[0045] It should be noted that “transparent to light in the used wavelength band” means that the transmittance of light can maintain the function as a polarizing element, and does not mean that the transmittance of light in the used wavelength band is 100%.

[0046] The shape of the main surface of the transparent substrate 11 is not particularly limited, and an example thereof is a rectangular shape. The average thickness of the transparent substrate 11 is not particularly limited, and an example thereof is 0.3 mm to 1 mm.

[0047] The transparent substrate 11 is preferably made of a material with a refractive index of 1.1 to 2.2. The material with a refractive index of 1.1 to 2.2 is not particularly limited, and examples thereof include glass, crystal, quartz, and sapphire. Among these, from the perspectives of cost and light transmittance, silicate glass and other glasses are preferred, with quartz with a refractive index of 1.46 and soda-lime glass with a refractive index of 1.51 being particularly preferred. Furthermore, from the perspective of thermal conductivity, crystal and sapphire are preferred. This improves the heat resistance of the transparent substrate 11, enabling its use in liquid crystal projectors.

[0048] It should be noted that when using an optically active crystal such as crystal or sapphire as the material constituting the transparent substrate 11, it is preferable to arrange the lattice-shaped protrusions 12 in a direction parallel to or perpendicular to the optical axis of the crystal. This can achieve excellent optical properties. Here, the optical axis of the crystal refers to the direction in which the difference in refractive index between O (ordinary ray) and E (extraordinary ray) for light traveling in that direction is minimized.

[0049] (Reflective layer)

[0050] The reflective layer 21 is formed on one surface of the transparent substrate 11 and forms a grid-like pattern of protrusions 12 extending in the Y-axis direction. The reflective layer 21 attenuates polarized waves (TE waves (S waves)) having an electric field component in the Y-axis direction and transmits polarized waves (TM waves (P waves)) having an electric field component in the X-axis direction.

[0051] The thickness of the reflective layer 21 is not particularly limited, and is, for example, 100 nm to 300 nm inclusive. The thickness of the reflective layer 21 is measured, for example, by electron microscopy.

[0052] The material constituting the reflective layer 21 is not particularly limited as long as it reflects light within the intended wavelength range. Examples include simple elements such as Al, Ag, Cu, Mo, Cr, Ti, Ni, W, Fe, Si, Ge, Te, and Nd, and alloys containing one or more of these elements. Among these, aluminum or aluminum alloys are preferred. It should be noted that the reflective layer 21 may also be an inorganic film other than a metal, or a resin film whose surface reflectivity is increased by coloring.

[0053] The film-forming method of the reflective layer 21 is not particularly limited, and examples thereof include a vapor deposition method and a sputtering method.

[0054] It should be noted that the reflective layer 21 may be a laminated body in which layers having different constituent materials are laminated.

[0055] (Dielectric layer)

[0056] The dielectric layer 22 is formed on the surface of the reflective layer 21, forming a grid-like pattern of protrusions 12 extending in the Y-axis direction. The thickness of the dielectric layer 22 is such that the phase of polarized light transmitted through the absorption layer 23 and reflected by the reflective layer 21 is shifted by half a wavelength relative to the polarized light transmitted through the absorption layer 23. Specifically, the thickness of the dielectric layer 22 is appropriately set within a range of 1 nm to 500 nm, which allows for adjusting the phase of polarized light and enhancing the interference effect. The thickness of the dielectric layer 22 can be measured, for example, using electron microscopy.

[0057] The material constituting the dielectric layer 22 is not particularly limited. Examples thereof include Si oxides such as SiO2, Al2O3, metal oxides such as beryllium oxide and bismuth oxide, MgF2, cryolite, germanium, titanium dioxide, silicon, magnesium fluoride, boron nitride, boron oxide, tantalum oxide, and carbon. Two or more materials may be used in combination. Among them, Si oxide and Ti oxide are preferred.

[0058] The refractive index of the dielectric layer 22 is preferably greater than 1.0 and less than 2.5. The optical properties of the reflective layer 21 are affected by the refractive index of the surrounding layer. Therefore, the optical properties of the polarizing element 10 can be controlled by selecting the material constituting the dielectric layer 22. Furthermore, by appropriately adjusting the thickness and refractive index of the dielectric layer 22, a portion of the TE wave reflected by the reflective layer 21 can be reflected back toward the reflective layer 21 upon passing through the absorption layer 23. This allows the TE wave passing through the absorption layer 23 to be attenuated by interference. By selectively attenuating the TE wave in this manner, the desired polarization properties can be achieved.

[0059] The film-forming method of the dielectric layer 22 is not particularly limited, and examples thereof include vapor deposition, sputtering, CVD (Chemical Vapor Deposition), and ALD (Atomic Layer Deposition).

[0060] It should be noted that the dielectric layer 22 may be a laminated body in which layers having different constituent materials are laminated.

[0061] (Absorbent layer)

[0062] The absorption layer 23 is formed on the surface of the dielectric layer 22 and forms a grid-like protrusion 12 extending in the Y-axis direction.

[0063] The thickness of the absorption layer 23 is not particularly limited, and is, for example, 5 nm to 50 nm. The thickness of the absorption layer 23 can be measured, for example, by electron microscopy.

[0064] The material constituting the absorption layer 23 is not particularly limited as long as it can absorb light in the operating wavelength band, and examples thereof include metal materials and semiconductor materials. Examples of metal materials include simple substances of 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 (such as β-FeSi2, MgSi2, NiSi2, BaSi2, CrSi2, CoSi2, and TaSi). Among these, materials containing Fe or Ta and Si are preferred.

[0065] When a semiconductor material is used as the material constituting the absorption layer 23, it is necessary to use a semiconductor material having a band gap energy that is less than or equal to the energy of light in the operating wavelength band. For example, when the light in the operating wavelength band is visible light, it is necessary to use a semiconductor material having a band gap energy that is less than or equal to the energy of light with a wavelength of 400 nm, that is, less than or equal to 3.1 eV.

[0066] The film-forming method of the absorption layer 23 is not particularly limited, and examples thereof include a vapor deposition method and a sputtering method.

[0067] It should be noted that the absorption layer 23 may be a laminated body in which layers having different constituent materials are laminated.

[0068] (Anti-reflection layer)

[0069] The antireflection layer 13 is formed on the other surface of the transparent substrate 11 and is, for example, a laminate in which low-refractive-index layers and high-refractive-index layers having different refractive indices are alternately laminated.

[0070] The material constituting the antireflection layer 13 is not particularly limited, and examples thereof include Si oxide, Ti oxide, Zr oxide, Al oxide, Nb oxide, and Ta oxide.

[0071] The thickness of the antireflection layer 13 is not particularly limited, and is, for example, 1 nm to 500 nm. The thickness of the antireflection layer 13 can be measured, for example, by electron microscopy.

[0072] The method for forming the antireflection layer 13 is not particularly limited. 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.

[0073] (Protective film)

[0074] The protective film 24 is formed on the surface of the transparent substrate 11 on the side where the lattice-shaped protrusions 12 are arranged, and the protective film 26 is formed on the surface of the antireflection layer 13. The materials constituting the protective films 24 and 26 are the same as those constituting the dielectric layer 22 described above.

[0075] The method for forming the protective films 24 and 26 is the same as the method for forming the dielectric layer 22 described above.

[0076] It should be noted that the protective film 24 and the protective film 26 may be a laminated body in which layers having different constituent materials are laminated.

[0077] [Method for manufacturing polarizing element]

[0078] The following describes a method for manufacturing the polarizing element 10. First, a reflective layer, a dielectric layer, and an absorption layer are stacked on one surface of a transparent substrate 11 in this order from the transparent substrate 11 side to form a laminate. Next, the laminate is selectively etched to form the lattice-shaped protrusions 12.

[0079] When forming the lattice-like protrusions 12, a one-dimensional lattice-like resist is patterned on a laminate formed on one surface of the transparent substrate 11, for example, by photolithography, nanoimprinting, or the like. Subsequently, the portions of the resist not subjected to the patterning are selectively etched to form the lattice-like protrusions 12. The etching method is not particularly limited, and examples thereof include dry etching using an etching gas suitable for the etching target.

[0080] Next, after forming a protective film 24 on the surface of the grid-shaped protrusions 12 and the surface of the transparent substrate 11 on which the grid-shaped protrusions 12 are formed, the surface of the protective film 24 is treated with a first water repellent and a second water repellent to form a water repellent film 25 .

[0081] The method for treating the surface of the protective film 24 with the first and second water repellent treatment agents 25a and 25b is not particularly limited as long as a waterproof film 25 can be formed in which areas treated with the first and second water repellent treatment agents 25a and 25b are unevenly distributed. For example, a method can be used in which portions of the surface of the protective film 24 are alternately treated with the first and second water repellent treatment agents 25a and 25b. In this case, the amount of the first water repellent treatment agent 25a per treatment is not particularly limited, and for example, 1.7×10 -5 mol / m 2 Above and 1.9×10 -5 mol / m 2 The treatment amount of the second water repellent agent 25b per treatment is not particularly limited, but is, for example, 8.6×10 -2 mol / m 2 Above and 8.7×10 -2 mol / m 2 the following.

[0082] On the other hand, on the other surface of the transparent substrate 11 , the antireflection layer 13 and the protective film 26 are stacked in this order from the transparent substrate 11 side.

[0083] [Optical equipment]

[0084] The polarizing element 10 can be applied to optical devices such as liquid crystal displays, liquid crystal projectors, head-up displays, and vehicle headlights. In particular, the polarizing element 10 is preferably applied to liquid crystal projectors because the waterproof film 25 has excellent heat resistance.

[0085] It should be noted that when the optical device includes multiple polarizing elements, at least one of the multiple polarizing elements can be polarizing element 10. For example, in a liquid crystal projector, at least one of the polarizing elements arranged on the incident side and the output side of the liquid crystal panel can be polarizing element 10.

[0086] As mentioned above, although embodiment of this invention was demonstrated, this invention is not limited to the said embodiment, The said embodiment can also be modified suitably within the range of the summary of this invention.

[0087] Example

[0088] Next, examples of the present invention will be described, but the present invention is not limited to the examples. In this example, the waterproof property of the waterproof film 25 was evaluated using a test piece imitating the polarizing element 10 .

[0089] [Comparative Example 1]

[0090] The surface of the silicon substrate was treated with trichloro(1H,1H,2H,2H-tridecafluoro-n-octyl)silane (FOTS) using the CVD method to form a water-repellent film. The amount of FOTS treated was set to 6.6×10 -5 mol / m 2 The contact angle of the silicon substrate with the water-repellent film formed thereon with respect to water was 106°. Note that the contact angle with respect to water was measured using the θ / 2 method.

[0091] Figure 3 The relationship between the amount of FOTS treated and the contact angle with water is shown. Figure 3 It can be seen that the contact angle relative to water increases with the increase of FOTS processing volume. When the FOTS processing volume reaches 6.6×10 -5 mol / m 2 Time saturation.

[0092] [Comparative Example 2]

[0093] The surface of the silicon substrate was treated with dichlorodimethylsilane (DDMS) using the CVD method to form a water-repellent film. At this time, the treatment amount of DDMS was set to 2.3×10 -2 mol / m 2 The contact angle of the silicon substrate with the water-repellent film formed thereon with respect to water was 103°.

[0094] Figure 4 It shows the relationship between the treatment amount of DDMS and the contact angle with water. Figure 4 It can be seen that the contact angle relative to water increases with the increase of DDMS treatment amount. When the DDMS treatment amount reaches 2.3×10 -2 mol / m 2 Time saturation.

[0095] [Example 1]

[0096] Using the CVD method, a portion of the surface of the silicon substrate was treated alternately with FOTS and DDMS to form a waterproof film. Specifically, the following operation was repeated three times: a portion of the surface of the silicon substrate was treated with FOTS for waterproofing, and then a portion of the surface of the silicon substrate was treated with DDMS for waterproofing. At this time, the amount of treatment using FOTS per cycle was set to 1.7×10 -5 mol / m 2 , set the DDMS-based processing capacity per time to 8.7×10 -3 mol / m 2The contact angle with water of the silicon substrate on which the water-repellent film was formed was 105°, which is between the contact angle with water of Comparative Example 1 and the contact angle with water of Comparative Example 2. Therefore, it is speculated that a water-repellent film was formed in which the areas treated with FOTS and the areas treated with DDMS were unevenly present (mixed).

[0097] [Oil repellency of waterproof membrane]

[0098] The polarizing element 10 on which the waterproof film 25 was formed under the same conditions as in Example 1, Comparative Example 1, and Comparative Example 2 was used to evaluate the oil repellency of the waterproof film 25. Specifically, oleic acid O was attached to the surface of the polarizing element 10 on the side where the lattice-shaped protrusions 12 were formed, and the amount of permeation in the Y-axis direction was measured (see Figure 5 ).

[0099] Figure 6 The evaluation results of the oil repellency of the water repellent films of the polarizing elements of Example 1, Comparative Example 1, and Comparative Example 2 are shown.

[0100] Depend on Figure 6 It is found that the oil repellency of the water repellent film of the polarizing elements of Example 1 and Comparative Example 1 is high. In contrast, the oil repellency of the water repellent film of the polarizing element of Comparative Example 2 is low because the polarizing element is not treated with a silane coupling agent containing a perfluoroalkyl group.

[0101] [Heat resistance of waterproof membrane]

[0102] The heat resistance of the water-repellent membrane 25 was evaluated using a polarizing element 10 having the water-repellent membrane 25 formed thereon under the same conditions as in Example 1, Comparative Examples 1, and 2. Specifically, the polarizing element 10 was stored in a clean oven at 350°C, and the change in the contact angle of the water-repellent membrane 25 relative to its initial value was evaluated.

[0103] Figure 7 The evaluation results of the heat resistance of the waterproof films of the polarizing elements of Example 1, Comparative Example 1, and Comparative Example 2 are shown.

[0104] Depend on Figure 7 It is found that the heat resistance of the water-repellent films of the polarizing elements of Example 1 and Comparative Example 2 is high. In contrast, the heat resistance of the water-repellent film of the polarizing element of Comparative Example 1 is low because the polarizing element is not treated with a silane coupling agent containing no perfluoroalkyl group.

[0105] [Optical properties]

[0106] The optical properties of the polarizing element 10, after forming the waterproof film 25 under the same conditions as in Example 1, Comparative Example 1, and Comparative Example 2, were evaluated. Specifically, the change in the transmission axis transmittance of the polarizing element 10 relative to that before forming the waterproof film 25 was evaluated. It should be noted that the transmission axis transmittance refers to the transmittance of polarized light (TM waves) incident on the polarizing element 10 in the X-axis direction.

[0107] Table 1 shows the evaluation results of the change in the transmission axis transmittance [%] of the polarizing elements of Example 1, Comparative Example 1, and Comparative Example 2 relative to the amount before the waterproof film was formed.

[0108] [Table 1]

[0109]

[0110] As shown in Table 1, the polarizing element of Example 1 has an increased transmission axis transmittance throughout the wavelength range of 430 to 680 nm. This is presumably because the refractive index of the water-repellent film 25 formed on the outermost surface of the polarizing element 10 is lowered, thereby reducing the reflectivity.

[0111] It should be noted that the optical properties of the polarizing element of Example 1 other than the transmission axis transmittance have a change rate that does not affect the use.

Claims

1. A polarizing element comprising: 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 a used wavelength band and extending in a predetermined direction; The lattice-shaped convex portion has a reflective layer, a dielectric layer and an absorption layer in order from the transparent substrate side; A water-repellent film is formed on the surface of the grid-shaped protrusions and the surface of the transparent substrate on the side where the grid-shaped protrusions are arranged. The water-repellent film has regions treated with a plurality of different water-repellent treatment agents unevenly.

2. The polarizing element according to claim 1, wherein The plurality of different water repellents include a first water repellent containing a perfluoroalkyl group and a second water repellent not containing a perfluoroalkyl group.

3. The polarizing element according to claim 2, wherein The first waterproofing agent is trichloro(1H,1H,2H,2H-perfluoro-n-octyl)silane, The second water repellent agent is dimethyldichlorosilane.

4. A method for manufacturing a polarizing element, comprising: a step of laminating a reflective layer, a dielectric layer, and an absorption layer in order from the transparent substrate side on one surface of the transparent substrate to form a laminate; a step of forming the lattice-shaped protrusions by selectively etching the laminate, and a step of treating the surfaces of the lattice-shaped protrusions and the surface of the transparent substrate on the side where the lattice-shaped protrusions are formed with the plurality of different water-repellent treatment agents to form the water-repellent film.

5. The method for manufacturing a polarizing element according to claim 4, wherein The waterproof film is formed by alternately treating the surface of the lattice-shaped protrusions and a portion of the surface of the transparent substrate on the side where the lattice-shaped protrusions are formed with the plurality of different water-repellent treatment agents. 6 . An optical device comprising the polarizing element according to claim 1 .

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