WO2019009151A1 - Optical member and optical system unit using same - Google Patents

Abstract

The purpose of the present invention is to provide an optical member that achieves both a high transmittance and extinction ratio for a P wave and a high reflectance for an S wave, and an optical system unit using the optical member. An optical member 10 has a wire grid part 2 where projections 2a formed by stacking a plurality of layers of different materials are arranged like a line-and-space pattern on a base material 1. The projections 2a are composed of a reflective layer 21 comprising a material of higher reflectivity than at least a layer adjacent thereto and another layer 22, with the reflective layer 21 formed at either the top or the base of the projections 2a. The thickness of the reflective layer 21 is less than the total thickness of the other layer 22.

Description

Optical member and optical system using the same

The present invention relates to an optical member and an optical system using the same.

Conventionally, a polarizer is used to control the optical characteristics of light from ultraviolet to visible light and near infrared light. For example, wire grid polarizers have advantages such as high heat resistance, high environmental resistance, high absorption with no P-wave absorption, high functionality, a wide wavelength range, high chromaticity reproducibility, and thinness possible. And are used for polarizers of liquid crystal displays, polarized illumination for photolithography, UV polarized illumination for light alignment, and the like.

The wire grid polarizer is formed by forming metal in a line and space shape on a substrate that transmits light such as glass or resin. The wire grid polarizer suppresses the diffraction by reducing the line-and-space pitch to half or less of the wavelength of the light, and the polarized light transmits the light perpendicular to the metal wire and reflects the parallel light. Act as a child.

Metal wire grid polarizers are characterized by their superior environmental resistance to heat and ultraviolet light compared to conventional resin-impregnated polyester impregnated with iodine, and they function as polarizers in a wide wavelength range from ultraviolet light to infrared light, etc. (E.g., Patent Document 1).

Furthermore, a reflective polarizer such as a wire grid can improve the utilization efficiency of light by reusing the reflected wave by inserting a phase difference plate between it and the opposing mirror.

Patent document 1: JP 2008-268295

As the performance of such a polarizer, the transmittance of polarized light to be transmitted (polarization of electric field perpendicular to the wire; hereinafter referred to as P wave), polarized light to be reflected (polarization of electric field parallel to the wire; hereinafter S wave) It is important to note that the transmissivity of the light source, the extinction ratio which is the ratio of these, and the reflectance of the S wave are important. Specifically, it is desirable that the transmittance of P wave is high and the transmittance of S wave is low (that is, the extinction ratio is high). In addition, in order to reuse the S wave, it is desirable that the reflectance of the S wave is high.

However, it has been difficult for materials used in conventional wire grid polarizers to simultaneously achieve high transmittance and extinction ratio of P wave and high reflectance of S wave with respect to light of a specific wavelength. For example, aluminum (Al) exhibits high reflectance over a wide wavelength range with respect to S waves, but the extinction ratio drops sharply at wavelengths shorter than 300 nm. On the other hand, wire grid polarizers that use metal tantalum (Ta) or semiconductor silicon (Si) exhibit higher extinction ratios than aluminum (Al) at wavelengths shorter than 300 nm, but they absorb light with S-waves. There is a problem that the reflectance is not sufficiently obtained.

Then, an object of this invention is to provide the optical member which can make compatible the high transmittance | permeability and extinction ratio of P wave, and the high reflectance of S wave, and an optical system apparatus using the same.

In order to achieve the above object, the optical member of the present invention has a wire grid portion in which projections formed by laminating a plurality of layers made of different materials are arranged in a line and space shape on a base material. The convex portion is formed on the top side or the substrate side of the convex portion and is formed of a reflective layer made of a material having a higher reflectance than at least the adjacent layer and the other layers, and the thickness of the reflective layer is , And the total thickness of the other layers.

In this case, as a material used for the reflective layer, aluminum (Al), silver (Ag), gold (Au), or an alloy thereof can be used.

The material used for any one of the other layers is tantalum (Ta), silicon (Si), niobium (Nb), molybdenum (Mo), tungsten (W), titanium oxide (TiO ₂ ), oxide Chromium (CrO ₂ ), niobium oxide (NbO ₂ ), titanium nitride (TiN), or their alloys can be used.

In addition, the thickness of the reflective layer may be thinner than any one of the other layers.

The reflection layer may have a thickness such that the air-converted optical path length determined from the effective refractive index at the position of the reflection layer reinforces in the direction of reflecting light of a predetermined wavelength.

In addition, at least one of the other layers may have a thickness such that the air-converted optical path length obtained from the effective refractive index at the position of the other layers strengthens in the direction of reflecting the light of the predetermined wavelength .

Further, according to the optical system device of the present invention, the optical member of the present invention described above, a light source for emitting light from the reflective layer side to the optical member, and a side opposite to the optical member with respect to the light source Providing a mirror for reflecting light to the side of the optical member, and a retardation element disposed between the mirror and the optical member for converting linearly polarized light into circularly polarized light or elliptically polarized light It features.

The optical member of the present invention may further include, on the side on which the reflective layer is formed, a retardation element that converts linearly polarized light into circularly polarized light or elliptically polarized light. In this case, the phase difference element portion can be composed of a concavo-convex structure.

When using the optical member which has the said phase difference element part, the optical system apparatus of this invention is the said optical member, the light source which irradiates light from the said reflection layer side with respect to the said optical member, With respect to the said light source The mirror may be disposed on the opposite side of the optical member and may reflect light toward the optical member.

The optical member of the present invention and the optical system using the same can achieve both high transmittance and extinction ratio of P wave and high reflectance of S wave.

It is a schematic sectional drawing which shows the optical member of this invention. It is a schematic perspective view which shows the optical member of this invention. It is a schematic sectional drawing which shows the manufacturing method of the optical member of this invention. It is a schematic sectional drawing which shows the manufacturing method of another optical member of this invention. It is a schematic sectional drawing which shows the optical system apparatus of this invention. It is a schematic perspective view which shows another optical member of this invention. It is a schematic sectional drawing which shows the manufacturing method of another optical member of this invention. It is a schematic sectional drawing which shows another optical system apparatus of this invention. It is a figure which shows the structure of the wire grid part of a comparative example and an Example. It is a graph which shows the transmittance | permeability and the reflectance of P wave of the optical member of the comparative example 1, and S wave. 5 is a graph showing the extinction ratio of the optical member of Comparative Example 1; It is a graph which shows the transmittance | permeability and the reflectance of P wave of the optical member of the comparative example 2, and S wave. It is a graph which shows the extinction ratio of the optical member of the comparative example 2. FIG. It is a graph which shows the transmittance | permeability and the reflectance of P wave of the optical member of Example 1, and S wave. 5 is a graph showing the extinction ratio of the optical member of Example 1. It is a graph which shows the transmittance | permeability and the reflectance of P wave of the optical member of Example 2, and S wave. 7 is a graph showing the extinction ratio of the optical member of Example 2. It is a graph which shows the transmittance | permeability and the reflectance of P wave of the optical member of Example 3, and S wave. 15 is a graph showing the extinction ratio of the optical member of Example 3.

Below, the optical member 10 of this invention is demonstrated. The optical member 10 of the present invention is, as shown in FIGS. 1 and 2, a wire grid portion 2 in which convex portions 2a in which a plurality of layers made of different materials are laminated on a base 1 are arranged in a line and space. The convex portion 2a is formed on the top side or the base side of the convex portion 2a, and includes the reflective layer 21 made of a material having a higher reflectance than at least the adjacent layer and the other layer 22. Ru.

The substrate 1 supports the wire grid portion 2 and is made of a dielectric that can transmit light. Any dielectric may be used as the dielectric, as long as it can transmit desired light. For example, inorganic compounds such as quartz and alkali-free glass can be used. Alternatively, a resin may be used. The shape of the substrate 1 may be any shape, and for example, as shown in FIGS. 1 and 2, the substrate 1 is formed in a substrate shape having parallel first and second surfaces.

The wire grid portion 2 has a concavo-convex structure formed on the base material 1, transmits the P wave of the incident light, and reflects the S wave. In the uneven structure, the protrusions 2a are arranged in a line and space shape. In the present specification, the P wave means the polarization of an electric field perpendicular to the line of the convex portion 2a, and the S wave means the polarization of the electric field parallel to the line of the convex portion 2a. The wire grid portion 2 is preferable in that the narrower the pitch of the concavo-convex structure and the higher the aspect ratio, the higher extinction ratio can be obtained over a wide wavelength range, particularly a short wavelength range. For example, in UV polarized light for photo alignment, a good extinction ratio is required in the ultraviolet light region of wavelength 220 to 380 nm, the pitch of the concavo-convex structure is 50 nm to 100 nm, the width of the convex portion 2a is 10 m to 50 nm, and the convex The aspect ratio of the part 2a is preferably 1 or more. In addition, in the liquid crystal display, a good extinction ratio is required in the visible region of a wavelength of 380 to 800 nm, the pitch of the concavo-convex structure is 50 nm to 300 nm, the width of the convex portion 2a is 25 nm to 200 nm, and the aspect ratio of the convex portion 2 a is One or more is preferable. Of course, the configuration of the wire grid portion 2 is such that the optimum value changes depending on the material, the incident wavelength of light, etc., and the numerical values are limited as long as they are designed with the technical idea of the present invention. It is not a thing.

The convex portion 2a is formed by laminating a plurality of layers made of different materials, and mainly the reflective layer 21 for controlling the reflection of the S wave, the transmittance of the P wave, and the quenching of the wire grid portion. It consists of other layers 22 to control the ratio.

The reflective layer 21 is formed on the light incident side of the convex portion 2a. Specifically, when light to be used is incident on the optical member 10 from the top side of the convex portion 2a, as shown in FIG. 1A, the reflective layer 21 is most on the top side of the convex portion 2a. When it is formed and incident from the base side of the convex portion 2a, as shown in FIG. 1 (b), the reflective layer 21 is formed most on the base side. Thereby, more S waves of the incident light can be reflected. When the reflective layer 21 is formed on the top of the convex portion 2a, a protective layer may be formed on the top to protect the reflective layer 21 as long as the function of the reflective layer 21 is not impaired. .

For the light used for the optical member 10, a material having a higher reflectance than that of at least the adjacent layer of the convex portion 2a is used as the reflectance of the reflective layer 21. The material used for the reflective layer 21 is, for example, aluminum (Al), silver (Ag), gold (Au), or an alloy thereof.

The thickness of the reflective layer 21 (A in FIG. 1C) should be as thin as possible within a range that can maintain at least a higher reflectivity than the adjacent layer so as not to reduce the extinction ratio of the wire grid portion. good. For example, the thickness A of the reflective layer 21 is formed thinner than the total thickness (B + C in FIG. 1C) of the layers 22 other than the reflective layer 21 among the layers constituting the convex portion. In addition, the thickness A of the reflective layer 21 is thinner than any one of the layers 22 other than the reflective layer 21 among the layers constituting the convex portion (B or C in FIG. 1C). Furthermore, it may be formed thinnest among the layers constituting the convex portion.

On the other hand, among the layers constituting the convex portion 2a, any other layer 22 excluding the reflective layer 21 can be used as long as the transmittance of P wave and the extinction ratio of the wire grid portion can be mainly controlled. Good, conventionally known ones can be used. The material of the convex portion 2 a is preferably such that electrons are excited by light used for the optical member 10. For example, metals or metal oxides having a small band gap are preferable. Specifically, tantalum (Ta), silicon (Si), niobium (Nb), molybdenum (Mo), tungsten (W), titanium oxide (TiO ₂ ) Chromium oxide (CrO ₂ ), niobium oxide (NbO ₂ ), titanium nitride (TiN), or an alloy thereof can be used.

In addition, it is preferable that the reflection layer 21 has a thickness such that the air-converted optical path length obtained from the effective refractive index at the position of the reflection layer 21 strengthens in the direction of reflecting light of a predetermined wavelength. In addition, with regard to at least any one of the other layers 22 as well, the air-converted optical path length obtained from the effective refractive index at the position of the other layers 22 has a thickness that strengthens in the direction of reflecting light of a predetermined wavelength Is preferred. Thereby, the reflected light of S wave can be used efficiently.

Next, an example of a method of manufacturing the above-described optical member 10 will be described. The manufacturing method of the optical member 10 mainly includes, for example, a reflective layer film forming process, another layer film forming process, a mask forming process, and a concavo-convex structure forming process.

Here, in the case where the reflective layer 21 is formed on the top side of the convex portion, as shown in FIG. 3A, the other layers are first formed in the other layer film forming step on the base material 1 such as glass. A film 220 to be 22 is formed, and then a film 210 to be the reflective layer 21 is formed in the reflective layer deposition step. When the reflective layer 21 is formed on the base 1 side of the convex portion 2a, as shown in FIG. 4A, the reflective layer 21 is first formed on the base 1 in the reflective layer forming step. After the film 210 is formed, a film 220 to be the other layer 22 may be formed in the other layer film forming process. As the film forming technique, conventionally known ones such as sputtering, vacuum evaporation, CVD and the like can be used.

In the mask formation step, the mask 25 for forming the concavo-convex structure of the wire grid portion 2 is formed on the film 210 to be the reflective layer 21 and the film 220 to be the other layer 22. For example, as shown in FIGS. 3 (b) and 4 (b), a resist application step of applying a resist 251 on the surface of the film 210 or 220 as shown in FIGS. 3 (c) and 4 (c). A resist pattern forming step of forming a resist pattern 252 for forming the concavo-convex structure of the wire grid portion 2 in the film of the resist using an imprint technique, a photolithography technique or the like may be used.

Further, in the concavo-convex structure forming step, the concavo-convex structure of the wire grid portion 2 is formed on the films 210 and 220 to be the reflective layer 21 or the other layer 22 by the mask 25 described above. In the concavo-convex structure forming step, as shown in FIGS. 3D and 4D, the films 210 and 220 are etched based on the resist pattern 252 of the mask, and as shown in FIGS. The remaining resist 251 may be removed to form a concavo-convex structure having a convex portion 2 a on the base 1 as shown in FIG.

Next, an optical system apparatus in which the utilization efficiency of light is improved by using the optical member 10 configured as described above will be described with reference to FIG. The optical device 100 of the present invention is mainly configured by the optical member 10 described above, the light source 20, the mirror 30, and the phase difference element 40.

The light source 20 emits light to the optical member 10 from the side of the reflective layer 21. Any device may be used as long as it emits light of wavelength λ, which is a use zone of the optical member 10, and, for example, a light emitting diode (LED), an arc lamp, a low pressure discharge lamp, organic electroluminescence (OEL), etc. Applicable The size of the wavelength λ may have a fixed width.

The mirror 30 is disposed on the side opposite to the optical member 10 with respect to the light source 20 and reflects light to the optical member 10 side. Any mirror may be used as the mirror 30 as long as it can reflect light to the optical member 10 side, and a conventionally known mirror may be used.

The retardation element 40 is disposed between the optical member 10 and the mirror 30, and converts linearly polarized light into circularly polarized light or elliptically polarized light. The retardation element 40 may be anything as long as it can convert linearly polarized light into circularly polarized light or elliptically polarized light, but for example, it has a concavo-convex structure on a transparent base material, and the phase difference in light passing through the structure It is possible to use one that gives The concavo-convex structure is formed in, for example, a line and space shape having a convex portion and a concave portion having a width smaller than the wavelength λ. The uneven structure may be integrally formed of the same substance as the base material, or may be formed of a substance different from the base material. Materials used for the convex portion of the concavo-convex structure include inorganic compounds such as quartz and non-alkali glass, and metals such as silver (Ag), gold (Au), aluminum (Al), nickel (Ni), copper (Cu), etc. Metal oxides such as silicon dioxide (SiO ₂ ) and aluminum oxide (Al ₂ O ₃ ), resins, and the like can be used. The retardation element 40 preferably has an ellipticity of 0.6 or more, preferably 0.7 or more, of light after converting linearly polarized light. Further, it is most preferable to impart a phase difference of 1⁄4 wavelength to the transmitted light.

The principle of the optical system apparatus 100 of the present invention configured as described above will be described based on FIG.

As the light L1 emitted from the light source 20, the light grid L2 of the optical member 10 transmits the light L2 of P wave and the light L3 of S wave is reflected. The reflected light L3 is converted into circularly polarized (or elliptically polarized) light L4 by the phase difference element 40. Subsequently, when the light L4 is reflected by the mirror 30, the light L4 becomes circularly polarized light or elliptically polarized light L5 in reverse rotation to that before reflection. When this light L5 passes through the phase difference element 40 again, it becomes linearly polarized light L6 having an angle different from that of the S wave. This light is again transmitted through the wire grid portion 2 to the light L2 of P wave and the light L3 of S wave is reflected. By repeating this, the light emitted from the light source 20 can be efficiently extracted as a P wave. In particular, when the phase difference provided by the phase difference element 40 is 1⁄4 wavelength, most light can be converted to P wave and transmitted through the wire grid portion 2 by one reflection by the mirror, Losses due to absorption can be minimized.

In addition, although the case where the optical member 10 and the phase difference element 40 were isolate | separated was demonstrated in the description of the said optical system apparatus 100, these are good also as integral. For example, as shown in FIG. 6, the second optical member 10A of the present invention converts the linearly polarized light into circularly polarized light or elliptically polarized light on the side on which the reflective layer 21 of the above-described optical member 10 is formed. The

The retardation element portion 3 has a concavo-convex structure formed on the retardation element base material 31, and converts linearly polarized light into circularly polarized light or elliptically polarized light. When the reflection layer 21 is formed on the top side of the convex portion 2a of the wire grid portion 2 as shown in FIG. 6A, the phase difference element portion 3 is formed on the top side, as shown in FIG. As shown to b), when it forms in the base-material 1 side of convex part 2a, it forms in the surface of the side which opposes the wire grid part 2 of the base material 1. As shown in FIG.

The phase difference element unit 3 can convert linearly polarized light into circularly polarized light when the phase difference given by the concavo-convex structure is 1⁄4 wavelength. It is preferable that at least the phase difference provided by the concavo-convex structure be such that the ellipticity after conversion of linear polarization by the retardation element 3 is 0.6 or more, preferably 0.7 or more. The shape of the concavo-convex structure may be any shape as long as it can give a phase difference to light transmitted through the structure, but for example, a line and n having a convex portion 3a and a concave portion 3b having a width smaller than the wavelength λ of the transmitted light. It can be formed like a space. The line of the convex portion 3a may be formed to intersect the line of the convex portion 2a of the wire grid portion at 45 degrees. In addition, the concavo-convex structure may be integrally formed of the same substance as the phase difference element base material 31 or may be formed of a substance different from the phase difference element base material 31. Materials used for the convex portion 3a of the concavo-convex structure include inorganic compounds such as quartz and alkali-free glass, and metals such as silver (Ag), gold (Au), aluminum (Al), nickel (Ni), copper (Cu) and the like A metal oxide such as silicon dioxide (SiO ₂ ) or aluminum oxide (Al ₂ O ₃ ) or a resin can be used. As the the material, preferably towards that electrons are not excited by light of wavelength lambda, silicon (SiO 2) _dioxide, metal oxides such as aluminum oxide (Al 2 _{O 3)} is applicable.

As an example of the concavo-convex structure, for example, when the phase difference element portion 3 made of silicon dioxide (SiO ₂ ) gives a phase difference of 1⁄4 wavelength to the reflected wave of the ultraviolet light of 254 nm and reuses it, a convex portion The width may be 50 nm, the pitch 100 nm, and the height of the convex portion 750 nm.

Next, a method of forming the phase difference element unit 3 will be described with reference to FIG. First, as shown to Fig.7 (a), the optical member 10 mentioned above is prepared. And as shown in FIG.7 (b), when the reflection layer 21 of the said optical member 10 is formed in the top part side of the convex part 2a, the silicon dioxide (The said convex part 2a is formed. The material of the phase difference element unit 3 such as SiO ₂ ) is deposited. The film formation may be performed by a conventionally known method, but it is formed by a film formation method with low step coverage, such as sputtering or evaporation, and a void is formed between the convex portions 2a of the concavo-convex structure. Is preferred. The film 310 formed by the film formation serves as the phase difference element base material 31 and also functions as a protective film for preventing the wire grid portion 2 from being deteriorated and the like. For example, when the wire grid portion 2 is irradiated with ultraviolet light, the metal or the like constituting the wire grid portion 2 is deteriorated due to oxidation or the like due to the generation of ozone or a temperature rise. However, the deterioration can be prevented by covering the retardation element base material 31 with silicon dioxide (SiO ₂ ) or the like by the film formation.

Next, the concavo-convex structure which functions as a phase difference element is formed in the base material 31 for phase difference elements. The formation of the concavo-convex structure can use a conventionally known method. For example, as shown in FIG. 7C, a mask forming step of forming a mask 35 having a mask pattern 352 for forming the concavo-convex structure of the retardation element portion 3 on the retardation element substrate 31 such as glass As shown in FIG. 7 (d), it comprises a concavo-convex structure forming step of forming the concavo-convex structure of the retardation element portion 3 on the retardation element substrate 31 based on the mask pattern 352.

The mask formation process includes a metal film formation process of forming a metal film such as chromium on the retardation element substrate 31 such as glass, a resist film formation process of applying a resist on the surface of the metal film, an imprint technique, A resist pattern forming step of forming a resist pattern for forming the concavo-convex structure of the phase difference element portion 3 on the resist film using a photolithography technique or the like, and forming a mask pattern 352 on the metal film based on the resist pattern The mask pattern forming step may be performed.

In the concavo-convex structure forming step, the substrate for retardation element 31 is etched based on the mask pattern 352 of the mask 35, and the remaining mask pattern 352 is removed as shown in FIG. The uneven structure having the convex portions 3 a may be formed on the element base 31.

When the reflective layer 21 of the optical member 10 is formed on the base 1 side of the convex portion 2 a, silicon dioxide (SiO ₂ ) or the like is formed on the surface of the base 1 facing the convex portion 2 a. The material of the phase difference element unit 3 may be formed into a film, and then the uneven structure may be formed. In this case, the base material 1 and the phase difference element base material 31 may be common.

When the second optical member 10A configured in this way is used, the phase difference element 40 of the above-described optical system device 100 becomes unnecessary. That is, as shown in FIG. 8, the second optical system apparatus 100A of the present invention may be configured by the optical member 10A, the light source 20, and the mirror 30. The optical member 10A is disposed so that the phase difference element unit 3 faces the light source 20 side. The optical member 10A, the light source 20, and the mirror 30 may be arranged in this order, and are the same as the optical system device 100 described above, and thus the description thereof will be omitted.

Next, simulation was used to calculate the optical characteristics of an optical system using the conventional optical member (comparative example) and the optical member of the present invention (example). For the simulation, software DiffractMOD manufactured by Synopsys, Inc. was used. As an optical system apparatus, what arranged the optical member 10, the phase difference element 40, the light source 20, and the mirror 30 in this order was assumed similarly to what was shown in FIG. Moreover, the optical member 10 was arrange | positioned so that the vertex side of convex part 2a of a wire grid part might turn into a light source side. The phase difference element 40 used what gave the phase difference of 1/4 wavelength to the light which passed.

Comparative Example 1
As an optical member of Comparative Example 1, as shown in FIG. 9 (a), on a substrate made of silicon dioxide (SiO ₂ ), convex portions with a height of 180 nm and a width of 43 nm, and a line and space with a pitch of 100 nm. Periodically arranged in the shape of a circle. The convex portion is a 160 nm thick Al layer made of aluminum (Al) formed on the substrate side, and a 20 nm thick SiO ₂ layer made of silicon dioxide (SiO ₂ ) formed on the top side of the Al layer. And The transmittance and the reflectance of P wave, the transmittance and the reflectance of S wave are shown in FIG. 10, and the extinction ratio is shown in FIG. 11 when light having a wavelength of 220 to 380 nm is incident on this optical member. .

The transmittance of P wave of the optical member is about 50% with respect to ultraviolet light of 254 nm used for light distribution control of the underlying resin of liquid crystal, which is 25% of the total incident wave. Further, the reflectance of the S wave of the optical member is about 73%. Assuming that the transmission of the phase difference element 40 and the reflection of the mirror 30 are both 100%, the amount by which the S wave reflected once is reflected by the mirror and transmitted is 73% × 25% = 18.3%. Therefore, the substantial transmittance is 25% + 18.3% = 43.3%, and a relatively good transmittance can be obtained.

On the other hand, the extinction ratio of the optical member to ultraviolet light of 254 nm is about 30. This is smaller than the extinction ratio of 100, which is a standard for efficiently orienting the resin, and is not a sufficient value.

Comparative example 2
As an optical member of Comparative Example 2, as shown in FIG. 9 (b), on a substrate made of silicon dioxide (SiO ₂ ), convex portions having a height of 120 nm and a width of 30 nm are line and space at a pitch of 100 nm. Periodically arranged in the shape of a circle. The convex portion is a 100 nm thick Ta layer made of tantalum (Ta) formed on the substrate side, and a 20 nm thick SiO ₂ layer made of silicon dioxide (SiO ₂ ) formed on the top side of the Ta layer. And The transmittance and the reflectance of P wave, the transmittance and the reflectance of S wave are shown in FIG. 12, and the extinction ratio is shown in FIG. 13, when light having a wavelength of 220 to 380 nm is incident on this optical member. .

The transmittance of P-wave of the optical member is about 54%, which is 27% of the total incident wave, to ultraviolet light of 254 nm used for light distribution control of the base resin of liquid crystal. Further, the reflectance of the S wave of the optical member is about 14%. Assuming that the transmission of the phase difference element 40 and the reflection of the mirror 30 are both 100%, the amount of the S wave reflected once and reflected by the mirror is 14% × 27% = 3.8%. Therefore, the substantial transmittance is 27% + 3.8% = 30.8%, and the transmittance is hardly improved by the reuse of the reflected light.

On the other hand, the extinction ratio of the optical member to ultraviolet light of 254 nm is about 300. This is a large and sufficient value as compared with the extinction ratio of 100, which is a standard for efficiently orienting the resin.

Example 1
As an optical member of Example 1, as shown in FIG. 9C, on a substrate made of silicon dioxide (SiO ₂ ), convex portions having a height of 120 nm and a width of 30 nm are line and space at a pitch of 100 nm. Periodically arranged in the shape of a circle. The convex portion is a 100 nm thick Ta layer (other layer 22) made of tantalum (Ta) formed on the substrate side, and a thickness 20 nm made of aluminum (Al) formed on the top side of the Ta layer. Al layer (reflective layer 21). The transmittance and the reflectance of P wave, the transmittance and the reflectance of S wave are shown in FIG. 14, and the extinction ratio is shown in FIG. 15 when light having a wavelength of 220 to 380 nm is incident on this optical member. .

The transmittance of P-wave of the optical member is about 54%, which is 27% of the total incident wave, to ultraviolet light of 254 nm used for light distribution control of the base resin of liquid crystal. Further, the reflectance of the S wave of the optical member is about 54%. Assuming that the transmission of the phase difference element 40 and the reflection of the mirror 30 are both 100%, the amount of the S wave that has once reflected and transmitted by the mirror is 54% × 27% = 14.6%. Therefore, the substantial transmittance is 27% + 14.6% = 41.6%, and a relatively good transmittance can be obtained.

On the other hand, the extinction ratio of the optical member to ultraviolet light of 254 nm is about 300. This is a large and sufficient value as compared with the extinction ratio of 100, which is a standard for efficiently orienting the resin.

Example 2
As an optical member of Example 2, as shown in FIG. 9D, on a substrate made of silicon dioxide (SiO ₂ ), convex portions having a height of 120 nm and a width of 30 nm, and a line and space at a pitch of 100 nm. Periodically arranged in the shape of a circle. The convex portion is a 100 nm thick Si layer (other layer 22) made of silicon (Si) formed on the substrate side, and a 20 nm thick made of aluminum (Al) formed on the top side of the Si layer. Al layer (reflective layer 21). The transmittance and the reflectance of P wave, the transmittance and the reflectance of S wave are shown in FIG. 16 and the extinction ratio is shown in FIG. 17 by simulation when light having a wavelength of 220 to 380 nm is incident on this optical member. .

The transmittance of P wave of the optical member is about 65% to 32.5% of the entire incident wave with respect to the ultraviolet light of 254 nm used for light distribution control of the base resin of liquid crystal. Further, the reflectance of the S wave of the optical member is about 68%. Assuming that the transmission of the phase difference element 40 and the reflection of the mirror 30 are both 100%, the amount of the S wave reflected once and reflected by the mirror is 68% × 32.5% = 22.1%. Become. Accordingly, the substantial transmittance is 32.5% + 22.1% = 54.6%, and a relatively good transmittance can be obtained.

On the other hand, the extinction ratio of the optical member to ultraviolet light of 254 nm is about 150. This is a large and sufficient value as compared with the extinction ratio of 100, which is a standard for efficiently orienting the resin.

Example 3
As an optical member of Example 3, as shown in FIG. 9 (e), on a substrate made of silicon dioxide (SiO ₂ ), convex portions having a height of 140 nm and a width of 30 nm are line and space at a pitch of 100 nm. Periodically arranged in the shape of a circle. The convex part is a 100 nm thick TiO ₂ layer (other layer 22) made of amorphous titanium oxide (TiO ₂ ) formed on the substrate side, and aluminum (Al) formed on the top side of the TiO ₂ layer. And a 20 nm thick SiO ₂ layer (protective layer) made of silicon dioxide (SiO ₂ ) formed on the top side of the Al layer. The transmittance and the reflectance of P wave, the transmittance and the reflectance of S wave are shown in FIG. 18 and the extinction ratio is shown in FIG. 19 when light having a wavelength of 220 to 380 nm is incident on this optical member. .

The transmittance of P wave of the optical member is about 60% to 30% of the total incident wave with respect to the ultraviolet light of 254 nm used for light distribution control of the base resin of liquid crystal. Further, the reflectance of the S wave of the optical member is about 60%. Assuming that the transmission of the phase difference element 40 and the reflection of the mirror 30 are both 100%, the amount of the S wave reflected once and reflected by the mirror is 60% × 30% = 18%. Therefore, the substantial transmittance is 30% + 18% = 48%, and a relatively good transmittance can be obtained.

On the other hand, the extinction ratio of the optical member to ultraviolet light of 254 nm is over 100. This is a large and sufficient value as compared with the extinction ratio of 100, which is a standard for efficiently orienting the resin.

The results of Comparative Examples 1 and 2 and Examples 1 to 3 are summarized in Table 1. When the optical member of the present invention (Examples 1 to 3) is used for the optical system device of the present invention, both the substantial transmittance and the extinction ratio can be improved.

1 substrate 2 wire grid portion 2a convex portion 3 phase difference element portion
10 Optical members
10A Optical member
20 light sources
21 Reflective layer
22 Other layers
30 mirror
40 phase difference element
100 Optical device
100A optical device

Claims (10)

An optical member having a wire grid portion in which projections formed by laminating a plurality of layers made of different materials on a substrate are arranged in a line and space shape,
The convex portion is formed of a reflective layer formed on a top side or a substrate side of the convex portion and made of a material having a higher reflectance than at least the adjacent layer, and other layers.
An optical member characterized in that a thickness of the reflective layer is thinner than a total thickness of the other layers. The optical member according to claim 1, wherein a material used for the reflective layer is aluminum (Al), silver (Ag), gold (Au), or an alloy thereof. Materials used for any one of the other layers are tantalum (Ta), silicon (Si), niobium (Nb), molybdenum (Mo), tungsten (W), titanium oxide (TiO ₂ ), chromium oxide The optical member according to claim 1 or 2, which is CrO ₂ ), niobium oxide (NbO ₂ ), titanium nitride (TiN), or an alloy thereof. The optical member according to any one of claims 1 to 3, wherein a thickness of the reflective layer is thinner than any one of the other layers. 5. The reflective layer according to any one of claims 1 to 4, wherein the air conversion optical path length determined from the effective refractive index at the position of the reflective layer has a thickness that reinforces in the direction of reflecting light of a predetermined wavelength. The optical member as described in. At least any one of the other layers is characterized in that the air-converted optical path length determined from the effective refractive index at the position of the other layer has a thickness that reinforces each other in the direction of reflecting light of a predetermined wavelength. The optical member according to any one of claims 1 to 5. The optical member according to any one of claims 1 to 6, further comprising: a phase difference element unit that converts linearly polarized light into circularly polarized light or elliptically polarized light on the side on which the reflective layer is formed. The optical member according to claim 7, wherein the phase difference element portion has a concavo-convex structure. An optical member according to any one of claims 1 to 6,
A light source for emitting light from the reflective layer side to the optical member;
A mirror disposed on the side opposite to the optical member with respect to the light source, for reflecting light toward the optical member;
A retardation element disposed between the mirror and the optical member for converting linearly polarized light into circularly polarized light or elliptically polarized light;
An optical system apparatus comprising: An optical member according to claim 7 or 8;
A light source for emitting light from the reflective layer side to the optical member;
A mirror disposed on the side opposite to the optical member with respect to the light source, for reflecting light toward the optical member;
An optical system apparatus comprising:

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