Film for optical element and method for producing same, inorganic polarizing plate and method for producing same, optical element and optical instrument
阅读说明：本技术 光学元件用薄膜及其制造方法、无机偏振片及其制造方法、以及光学元件和光学仪器 (Film for optical element and method for producing same, inorganic polarizing plate and method for producing same, optical element and optical instrument ) 是由 菅原利明 高田昭夫 于 2020-03-27 设计创作，主要内容包括：本发明提供：作为吸收型无机偏振片等光学元件中使用的单层薄膜的光学元件用薄膜及其制造方法、使用了该光学元件用薄膜的无机偏振片及其制造方法、具备该光学元件用薄膜的光学元件、以及具备该无机偏振片的光学仪器。无机偏振片(20)是具有线栅结构的无机偏振片,具备透明基板(21)和以短于使用频带的光的波长的间距排列在透明基板(21)上的格子状凸部(22),格子状凸部(22)从透明基板(21)侧起依次具有反射层(221)和由本发明的光学元件用薄膜构成的反射抑制层(222)。本发明的光学元件用薄膜含有Si单质、Si化合物(其中,除外Si合金)和金属或金属化合物。(The present invention provides: a film for optical elements, which is a single-layer film used in optical elements such as an absorbing inorganic polarizing plate, and a method for producing the same, an inorganic polarizing plate using the film for optical elements, and a method for producing the same, an optical element provided with the film for optical elements, and an optical instrument provided with the inorganic polarizing plate. The inorganic polarizing plate (20) is an inorganic polarizing plate having a wire grid structure, and comprises a transparent substrate (21) and grid-like projections (22) arranged on the transparent substrate (21) at a pitch shorter than the wavelength of light in a use frequency band, wherein the grid-like projections (22) have, in order from the transparent substrate (21) side, a reflection layer (221) and a reflection suppression layer (222) comprising the optical element film of the present invention. The thin film for an optical element of the present invention contains a simple substance of Si, a compound of Si (except Si alloy) and a metal or a metal compound.)
1. A film for optical elements, which is a single-layer film used in optical elements,
the thin film for an optical element contains a simple Si substance, a Si compound, and a metal or metal compound, wherein the Si compound is excluded from the Si alloy.
2. The film for optical elements as claimed in claim 1, wherein a mixing ratio of the simple substance Si, the compound Si and the metal or metal compound varies in a film thickness direction.
3. The thin film for an optical element as claimed in claim 1 or 2, wherein the Si compound is a carbide or an oxide of Si.
4. The film for an optical element according to any one of claims 1 to 3, which contains an oxide of Nb as the metal or the metal compound.
5. A method for producing a film for an optical element according to any one of claims 1 to 4, comprising the steps of:
and a step of performing reactive sputtering in the presence of an oxidizing gas by using a carbide of Si and a metal or a metal compound as a sputtering target.
6. An inorganic polarizing plate having a wire grid structure, the inorganic polarizing plate comprising:
a transparent substrate; and
lattice-like projections arranged on the transparent substrate at a pitch shorter than the wavelength of light in a use frequency band,
wherein the lattice-like projections have, in order from the transparent substrate side, a reflection layer and a reflection suppressing layer comprising the thin film for optical element according to any one of claims 1 to 4.
7. The inorganic polarizing plate according to claim 6, wherein the width of the reflection suppressing layer is smaller than the width of the reflection layer.
8. The inorganic polarizing plate according to claim 6 or 7, further comprising a protective film covering the surface of the lattice-shaped protrusions.
9. The inorganic polarizing plate according to claim 8, wherein the protective film comprises at least one of an inorganic oxide film and a fluorine-based water-repellent film.
10. A method for manufacturing an inorganic polarizing plate having a wire grid structure, comprising the steps of:
a step of forming a laminate having a reflection layer and a reflection suppressing layer comprising the thin film for optical element according to any one of claims 1 to 4 on a transparent substrate in this order from the transparent substrate side; and
and forming lattice-shaped projections arranged on the transparent substrate at a pitch shorter than the wavelength of light in the use frequency band by selectively etching the laminate.
11. An optical element comprising the film for optical element according to any one of claims 1 to 4.
12. An optical device comprising the inorganic polarizing plate according to any one of claims 6 to 9.
Technical Field
The present invention relates to a film for an optical element and a method for producing the same, an inorganic polarizing plate and a method for producing the same, and an optical element and an optical instrument.
Background
The polarizing plate is an optical element that absorbs or reflects polarized light in one direction and transmits polarized light in a direction perpendicular thereto. In recent years, in optical instruments such as liquid crystal projectors, which require heat resistance, a wire grid (wire grid) type inorganic polarizing plate has been used instead of an organic polarizing plate.
The wire grid type inorganic polarizing plate includes at least a reflective layer, and has a structure in which a plurality of grid-like projections extending in one direction are arranged in parallel on a transparent substrate at a pitch (several tens nm to several hundreds nm) shorter than the wavelength of light in a use frequency band. When light enters the inorganic polarizing plate, polarized light having an electric field component (TE wave (S wave)) parallel to the extending direction of the lattice-shaped protrusions cannot pass therethrough, while polarized light having an electric field component (TM wave (P wave)) perpendicular to the extending direction of the lattice-shaped protrusions passes therethrough.
The inorganic polarizing plates include an absorption-type inorganic polarizing plate and a reflection-type inorganic polarizing plate, and in the case of the absorption-type inorganic polarizing plate, high contrast, that is, low reflectance is regarded as an important requirement in optical characteristics. When the reflectance of the inorganic polarizing plate is high, there is a concern that the reflectance may cause a failure of an optical device, and there is a concern that the image quality may be deteriorated due to stray light. Therefore, conventionally, in order to suppress the reflectance to a low level, various structures of inorganic polarizing plates have been proposed.
For example, patent document 1 discloses an inorganic polarizing plate having a structure shown in fig. 7. The inorganic polarizing
Patent document 2 discloses an inorganic polarizing plate including a transparent substrate and lattice-like projections arranged on the transparent substrate at a pitch shorter than the wavelength of light in a use frequency band, wherein the lattice-like projections have a reflective layer, a dielectric layer, an absorbing layer, and a dielectric layer in this order from the transparent substrate side.
Disclosure of Invention
Problems to be solved by the invention
According to the inorganic polarizing plates having the structures described in patent documents 1 and 2, the TE wave (S wave) can be attenuated and the TM wave (P wave) can be transmitted by utilizing the actions of absorption, interference, reflection, and the like of the reflective layer, the dielectric layer, and the absorptive layer. However, in view of the cost and yield in production, it is preferable that the number of layers is small. In addition, when the lattice-shaped convex portions are formed by etching, if the number of layers is large, a step (step difference) is generated at the boundary portion, and there is a concern that the optical characteristics are adversely affected. From this point of view, it is also preferable that the number of layers is small.
The present invention has been made in view of the above circumstances, and an object thereof is to provide: a film for optical elements, which is a single-layer film used in optical elements such as an absorbing inorganic polarizing plate, and a method for producing the same, an inorganic polarizing plate using the film for optical elements, and a method for producing the same, an optical element provided with the film for optical elements, and an optical instrument provided with the inorganic polarizing plate.
Means for solving the problems
In order to achieve the above object, the present invention provides a thin film for an optical element, which is a single-layer thin film used in an optical element, and contains Si, an Si compound (except Si alloy) and a metal or a metal compound.
The thin film for optical element may be a thin film in which the composition ratio of Si, the Si compound, and the metal or the metal compound changes in the film thickness direction.
The above-mentioned Si compound may be a carbide or an oxide of Si.
The optical element thin film may contain an oxide of Nb as the metal or the metal compound.
The present invention also provides a method for producing a film for an optical element, the method comprising: and a step of performing reactive sputtering in the presence of an oxidizing gas by using a carbide of Si and a metal or a metal compound as a sputtering target.
The present invention also provides an inorganic polarizing plate having a wire grid structure, the inorganic polarizing plate including a transparent substrate and grid-like projections arranged on the transparent substrate at a pitch shorter than the wavelength of light in a use frequency band, wherein the grid-like projections have a reflection layer and a reflection suppression layer formed of the optical element thin film in this order from the transparent substrate side.
The width of the reflection-suppressing layer may be smaller than the width of the reflection layer.
The inorganic polarizing plate may further include a protective film covering the surface of the lattice-shaped convex portion.
The protective film may include at least one of an inorganic oxide film and a fluorine-based waterproofing film.
The present invention also provides a method for manufacturing an inorganic polarizing plate having a wire grid structure, comprising the steps of: a step of forming a laminate having a reflective layer and a reflection suppressing layer composed of the optical element thin film on a transparent substrate in this order from the transparent substrate side; and forming lattice-shaped projections arranged on the transparent substrate at a pitch shorter than the wavelength of light in a use frequency band by selectively etching the laminate.
The present invention also provides an optical element comprising the film for an optical element.
The present invention also provides an optical device including the inorganic polarizing plate.
Effects of the invention
According to the present invention, there can be provided: a film for optical elements, which is a single-layer film used in optical elements such as an absorbing inorganic polarizing plate, and a method for producing the same, an inorganic polarizing plate using the film for optical elements, and a method for producing the same, an optical element provided with the film for optical elements, and an optical instrument provided with the inorganic polarizing plate.
Drawings
FIG. 1 is a schematic view showing an example of a reactive sputtering apparatus.
Fig. 2 is a schematic cross-sectional view showing an example of the inorganic polarizing plate according to the present embodiment.
FIG. 3 is a graph showing the results of measuring the reflectance with respect to the test panels of example 1 and comparative example 1.
FIG. 4 is a graph showing the results of measuring the reflectance with respect to the test plates of examples 2 and 3.
FIG. 5A is a graph showing the results of measuring the reflectance before and after the heat test on the test plate of example 1.
FIG. 5B is a graph showing the results of measuring the reflectance before and after the heat test with respect to the test plate of comparative example 2.
FIG. 6A is a graph showing the results of measuring the reflectance before and after the heat test on the test plate of example 4.
FIG. 6B is a graph showing the results of measuring the reflectance before and after the heat test on the test plate of example 5.
FIG. 7 is a schematic cross-sectional view showing an example of a conventional inorganic polarizing plate.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[ film for optical element ]
The thin film for an optical element according to the present embodiment is a thin film for an optical element which is a single-layer thin film used for an optical element, and contains Si, an Si compound (except Si alloy) and a metal or a metal compound.
The Si and Si compound in the thin film for optical element according to the present embodiment are formed of, for example, SixA sputtering target composed of C (x =2.3 ± 0.2) is obtained by reactive sputtering in the presence of an oxidizing gas. Using a catalyst composed of SixThe composition of the Si compound in the thin film obtained from the sputtering target composed of C (x =2.3 ± 0.2) is SiaObCcAnd (4) showing. In a so-called metal mode in which the flow rate of the oxidizing gas is zero, the oxidizing gas is introduced as a Si simple substance,Or high refractive index components such as SiC having a relatively large composition of C. In the so-called reaction mode in which the flow rate of the oxidizing gas is large, SiO having a relatively large O composition is usedy(y is not more than 2) and the like. When the flow rate of the oxidizing gas is large, the component C in the target reacts with the oxidizing gas in the environment to form CO during film formation2Or CO, and is exhausted by a vacuum pump or the like.
Examples of the metal or metal compound in the film for an optical element according to the present embodiment include: a simple substance of at least 1 element selected from Nb, Fe, Ta, Si, Ti, Mg, W, Mo and Al (wherein the simple substance of Si is excluded), an oxide (wherein the oxide of Si is excluded), an alloy, and the like. Examples of the alloy include NbSi alloy, FeSi alloy, and TaSi alloy. These metal materials may be used alone in 1 kind, or may be used in combination in 2 or more kinds. Among these, NbO is preferable from the viewpoint of heat resistance and extinction coefficient of the film for optical elementsx(x is less than or equal to 2.5), and the like.
As described later, by adjusting the sputtering conditions at the time of forming the thin film for an optical element and adjusting the composition ratio of C and O in the Si compound or the mixing ratio of the Si simple substance, the Si compound, and the metal or metal compound, a thin film for an optical element having desired optical characteristics can be obtained.
The refractive index and extinction coefficient at a wavelength of 550nm of the main components that can be contained in the optical element film according to the present embodiment are shown in table 1 below.
[ Table 1]
Composition (I)
Refractive index (550nm)
Extinction coefficient
Si
4.09
4.1×10-2
SiC
3.43
3.7×10-1
SiO
1.98
4.8×10-3
SiO2
1.47
1.9×10-3
Nb2O5
2.36
3.0×10-5
Examples of the film for an optical element according to the present embodiment include: NbOx(x is less than or equal to 2.5) is 1atm% -20 atm%, SiOy(y is less than or equal to 2) of 0atm% to 30atm%, Si simple substance content of 15atm% to 80atm%, and SiC content of 15atm% to 80atm%, the respective contents being adjusted according to desired optical characteristics.
The thin film for an optical element according to the present embodiment may be a thin film in which the mixing ratio of the Si simple substance, the Si compound, and the metal or metal compound changes in the film thickness direction. For example, a film can be formed such that the proportion of a low refractive index component (e.g., an oxide of Si) is relatively large on the substrate side of the optical element thin film and a high refractive index component (e.g., SiC, NbO) is formed on the opposite side of the substratexEtc.) are relatively large. Alternatively, the ratio of the low refractive index component to the high refractive index component may be continuously changed and the film formation may be repeated。
The thickness of the thin film for an optical element according to the present embodiment may be, for example, 10nm to 1000nm, and is arbitrarily selected according to the intended use and the like. The film thickness of the thin film for optical element can be easily adjusted by adjusting the sputtering time in reactive sputtering described later.
By adjusting the film thickness of the optical element thin film, the center wavelength at which the reflectance is minimized can be shifted to a desired wavelength. In addition, the thin film for an optical element according to the present embodiment is unlikely to cause a drift in reflectance as a whole even if the center wavelength of reflectance is shifted by changing the film thickness.
[ method for producing film for optical element ]
The film for an optical element according to the present embodiment can be produced, for example, by a production method including the steps of: and a step of performing reactive sputtering in the presence of an oxidizing gas by using a carbide of Si and a metal or a metal compound as a sputtering target.
The carbide of Si as the sputtering target is preferably made of SixC (x =2.3 ± 0.2). By using such a sputtering target, a thin film for an optical element containing a carbide and an oxide of Si can be easily obtained. In addition, Si is substituted by SixA sputtering target made of C (x =2.3 ± 0.2) can be produced by, for example, mixing 1 part by mass of SiC powder and 1.1 to 1.5 parts by mass of Si powder and sintering the mixture.
In the case of sputtering Si carbide as a sputtering target, the output of the sputtering power source (output) is preferably: LF power (パワー) is set to 5kW to 10kW, and RF power is set to 0kW to 5 kW.
The metal or metal compound as the sputtering target is appropriately selected depending on the kind of the metal or metal compound contained in the thin film for an optical element. For example, the film for optical elements contains NbOx(x.ltoreq.2.5), the element Nb or NbO may be usedx(x is more than or equal to 1.0 and less than or equal to 2.5). Among these, from the viewpoint of film formation rate, NbO is preferably usedx(x is more than or equal to 1.0 and less than or equal to 2.5).
In the case of sputtering a metal or a metal compound as a sputtering target, the output power of the sputtering power supply is preferably: LF power is set to 0.4kW to 10kW, and RF power is set to 0kW to 5 kW.
The process gas used for reactive sputtering is not particularly limited as long as it contains an oxidizing gas, and for example, a mixed gas of an oxidizing gas and an inert gas is used. Examples of the oxidizing gas include oxygen and ozone. Examples of the inert gas include helium, neon, argon, krypton, and xenon.
In the production method according to the present embodiment, the concentration of the oxidizing gas is controlled by adjusting the gas amount of the oxidizing gas, whereby the composition ratio of the Si compound in the thin film can be arbitrarily controlled. For example, using Si as a single sputter targetxC (x =2.3 ± 0.2), a high refractive index component containing SiC as a main component can be increased by reactive sputtering in an oxidizing gas atmosphere of low concentration, and SiO can be increased by reactive sputtering in an oxidizing gas atmosphere of high concentration2A low refractive index component as a main component. The low-concentration oxidizing gas atmosphere includes, for example, Ar gas at a flow rate of 100sccm to 1000sccm and O2The gas flow is 0 sccm-100 sccm. Further, as the oxidizing gas atmosphere of high concentration, for example, Ar gas flow rate of 100sccm to 1000sccm, and O2The gas flow is a mixed gas environment of 120sccm to 200 sccm.
The reactive sputtering apparatus used for producing the thin film for optical elements is not particularly limited as long as it can perform double (binary) simultaneous reactive sputtering. Examples of the reactive sputtering method include a radical assist sputtering method and a Meta Mode (メタモード) method.
An example of a reactive sputtering apparatus is shown in the schematic diagram of fig. 1. The
In the case of producing the thin film for an optical element according to the present embodiment, for example, Si is used as the
When the mixing ratio of the Si simple substance, the Si compound, and the metal or the metal compound in the thin film for an optical element is changed in the film thickness direction, the output power of the sputtering
[ optical element ]
The optical element according to the present embodiment includes the film for an optical element according to the present embodiment. Examples of the optical element according to the present embodiment include an inorganic polarizing plate, an antireflection film, and a color filter. Among these, an inorganic polarizing plate is preferable.
[ inorganic polarizing plate ]
The inorganic polarizing plate according to the present embodiment is an inorganic polarizing plate having a wire grid structure, and includes a transparent substrate and grid-like convex portions arranged on the transparent substrate at a pitch shorter than the wavelength of light in a use frequency band, wherein the grid-like convex portions include, in order from the transparent substrate side, a reflection layer and a reflection suppressing layer made of the optical element thin film according to the present embodiment.
Fig. 2 is a schematic cross-sectional view showing an example of the inorganic polarizing plate according to the present embodiment. As shown in fig. 2, the inorganic
In the present specification, as shown in fig. 2, the extending direction of the lattice-shaped projections 22 is referred to as the Y-axis direction. The direction perpendicular to the Y-axis direction and along which the lattice-shaped projections 22 are arranged along the main surface of the transparent substrate 21 is referred to as the X-axis direction. In this case, the light incident on the inorganic
The inorganic
As the transparent substrate 21, a substrate which shows transparency to light in a use frequency band is used. The phrase "show light transmittance in a use frequency band" does not mean that the transmittance of light in the use frequency band is 100%, and it is sufficient that the light transmittance is maintained as a function of the inorganic polarizing plate. The light in the use frequency band includes, for example, visible light having a wavelength of about 380nm to 810 nm.
The material constituting the transparent substrate 21 is preferably a material having a refractive index of 1.1 to 2.2, and examples thereof include glass, crystal, sapphire and the like. As a material for forming the transparent substrate 21, glass is more preferable from the viewpoint of cost and light transmittance.
The shape of the main surface of the transparent substrate 21 is not particularly limited, and a shape (for example, a rectangular shape) suitable for the purpose is appropriately selected. The average thickness of the transparent substrate 21 is preferably 0.3mm to 1mm, for example.
The lattice-shaped projections 22 are arranged on the transparent substrate 21 at a pitch P shorter than the wavelength of light in the use frequency band. The pitch P of the lattice-shaped projections 22 is not particularly limited as long as it is shorter than the wavelength of light in the use frequency band. The pitch P of the lattice-shaped projections 22 is preferably, for example, 100nm to 200nm from the viewpoint of ease of production and stability. The pitch P of the lattice-shaped convex portions 22 can be measured by observation using a scanning electron microscope or a transmission electron microscope. For example, the pitch may be measured for any 4 positions using a scanning electron microscope or a transmission electron microscope, and the arithmetic average of the pitches may be used as the pitch of the lattice-shaped convex portion 22. Hereinafter, this measurement method is referred to as an electron microscopy.
The width W of the lattice-shaped protrusions 22 is not particularly limited, and is preferably smaller than the width of the recesses between the lattice-shaped protrusions 22, from the viewpoint of suppressing redeposition when the lattice-shaped protrusions 22 are formed by etching. Specifically, the width W of the lattice-shaped projection 22 is preferably 35nm to 45nm, for example. The width W of the lattice-shaped projection 22 can be measured by the electron microscopy described above at the center of the height of the lattice-shaped projection 22.
The reflective layer 221 constituting the lattice-shaped projections 22 is formed on the transparent substrate 21 and is formed by arranging metal films extending in a band shape in the Y-axis direction as the absorption axis. The reflective layer 221 functions as a wire-grid polarizer, and attenuates a polarized wave having an electric field component (TE wave (S wave)) in a direction parallel to the longitudinal direction (longitudinal direction) of the reflective layer 221, and transmits a polarized wave having an electric field component (TM wave (P wave)) in a direction perpendicular to the longitudinal direction of the reflective layer 221.
The material constituting the reflective layer 221 is not particularly limited as long as it is a material having reflectivity for light in the use frequency band, and examples thereof include: simple substances of Al, Ag, Cu, Mo, Cr, Ti, Ni, W, Fe, Si, Ge, Te and the like or alloys containing more than 1 of the elements. Among them, the reflective layer 221 is preferably made of Al, Al alloy, or Ag.
The thickness of the reflective layer 221 is preferably 100nm to 300nm, for example. The film thickness of the reflective layer 221 can be measured by, for example, the electron microscopy method described above.
The reflection suppressing layer 222 constituting the lattice-shaped convex portion 22 is composed of the optical element thin film according to the present embodiment, and is laminated on the reflection layer 221. The optical element film is described above, and detailed description is omitted.
The thickness of the reflection-suppressing layer 222 is not particularly limited as long as it is thinner than the thickness of the reflection layer 221, and is preferably 10nm to 100nm, for example. The film thickness of the reflection suppressing layer 222 can be measured by, for example, the electron microscopy described above.
In fig. 2, the width of the reflection layer 221 and the width of the reflection suppression layer 222 are set to be substantially the same size, but the configuration is not limited thereto, and the width of the reflection suppression layer 222 may be set smaller than the width of the reflection layer 221. With such a configuration, the transmittance of the inorganic
The inorganic
Examples of the protective film include a film containing at least one of an inorganic oxide film and a fluorine-based water-repellent film. Examples of the inorganic oxide film include an Si oxide film and an Hf oxide film. Examples of the fluorine-based water-repellent film include films formed by coating a fluorine-based silane compound such as perfluorodecyltriethoxysilane (FDTS). The protective film can be formed by a CVD method (chemical vapor deposition method), an ALD method (atomic layer deposition method), or the like.
[ method for producing inorganic polarizing plate ]
The inorganic polarizing plate according to the present embodiment described above can be produced by a production method including the steps of: a step of forming a laminate having a reflection layer and a reflection suppressing layer composed of the thin film for an optical element according to the present embodiment described above on a transparent substrate in this order from the transparent substrate side; and forming lattice-shaped projections arranged on the transparent substrate at a pitch shorter than the wavelength of light in the use frequency band by selectively etching the laminate.
Hereinafter, a method for manufacturing an inorganic polarizing plate having a structure as shown in fig. 2 will be described as an example.
First, a reflective layer is formed on a transparent substrate. Examples of the method for forming the reflective layer include sputtering and vapor deposition.
Then, a reflection suppressing layer is formed on the reflective layer. The method of forming the reflection suppressing layer is the same as the method of manufacturing the thin film for an optical element according to the present embodiment described above, and therefore, detailed description thereof is omitted.
Then, a one-dimensional lattice-shaped mask pattern is formed on the reflection suppressing layer by a photolithography (photolithography) method, a nanoimprint (nanoimprint) method, or the like. Then, a stacked body composed of the reflection layer and the reflection suppressing layer is selectively etched to form lattice-shaped projections arranged on the transparent substrate at a pitch shorter than the wavelength of light in the use frequency band. As an etching method, for example, a dry etching method using an etching gas corresponding to an etching target can be cited.
By the above manufacturing method, an inorganic polarizing plate having a structure as shown in fig. 2 can be manufactured. The method for producing an inorganic polarizing plate according to the present embodiment may further include a step of covering the surface of the lattice-shaped convex portions with a protective film.
[ optical instruments ]
The optical device according to the present embodiment includes the inorganic polarizing plate according to the present embodiment. Examples of the optical device according to the present embodiment include a liquid crystal projector, a Head Up Display (Head Up Display), and a digital camera. The inorganic polarizing plate according to the present embodiment is superior in heat resistance to the organic polarizing plate, and is therefore suitable for applications such as liquid crystal projectors and head-up displays, which require heat resistance.
When the optical apparatus according to the present embodiment includes a plurality of inorganic polarizing plates, at least 1 of the plurality of inorganic polarizing plates may be the inorganic polarizing plate according to the present embodiment. For example, when the optical device according to the present embodiment is a liquid crystal projector, at least one of the inorganic polarizing plates disposed on the incident side and the emission side of the liquid crystal panel may be the inorganic polarizing plate according to the present embodiment.
The present invention is not limited to the above-described embodiments, and variations and modifications within a range that can achieve the object of the present invention are also included in the present invention.
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