WO2023106374A1

WO2023106374A1 - Optical element and method for manufacturing same

Info

Publication number: WO2023106374A1
Application number: PCT/JP2022/045311
Authority: WO
Inventors: 高宏俣野; 寛典高瀬; 隆史西宮
Original assignee: 日本電気硝子株式会社
Priority date: 2021-12-09
Filing date: 2022-12-08
Publication date: 2023-06-15

Abstract

Provided is an optical element which has excellent optical characteristics and which makes it possible to suppress damage to a relief layer.　An optical element according to the present invention comprises a light-transmitting substrate and a relief layer that is disposed on a main surface of the light-transmitting substrate and that has projections and recesses on a surface thereof, wherein the relief layer contains inorganic nanoparticles, and an absolute value of the difference between the refractive index of the light-transmitting substrate and the refractive index of the relief layer is not more than 0.20.

Description

Optical element and its manufacturing method

The present invention relates to an optical element and its manufacturing method.

Optical devices such as goggles for cameras, AR (Augmented Reality), VR (Virtual Reality) and MR (Mixed Reality) use optical elements.

As an example of the above optical element, Patent Document 1 below discloses a light-transmitting substrate and an inorganic material layer formed on the light-transmitting substrate and having a plurality of linear concave-convex structures parallel to each other. An optical element is disclosed comprising: In this optical element, the inorganic material layer has a refractive index of 1.8 or more.

JP 2015-210416 A

By using an optical element having an uneven surface and an uneven layer formed of an inorganic material, the optical characteristics can be improved to some extent. However, in recent years, the performance of optical equipment has been improved, and further improvement in optical characteristics is required.

Further, in a conventional optical element including a translucent substrate and an uneven layer, the uneven layer may be peeled off or damaged due to heat, impact, or the like.

An object of the present invention is to provide an optical element that has excellent optical properties and that can suppress damage to the uneven layer. Another object of the present invention is to provide a method for manufacturing the optical element. In this specification, optical properties refer to refractive index, light transmittance, and diffraction properties.

Each aspect of the optical element and its manufacturing method for solving the above problems will be described.

An optical element according to aspect 1 includes a light-transmitting substrate and an uneven layer disposed on a main surface of the light-transmitting substrate and having unevenness on the surface thereof, wherein the uneven layer comprises inorganic nanoparticles. and the absolute value of the difference between the refractive index of the translucent substrate and the refractive index of the uneven layer is 0.20 or less. When the absolute value of the difference in refractive index between the translucent substrate and the uneven layer is 0.20 or less, the reflection loss can be reduced and the viewing angle of optical equipment such as goggles can be widened.

In the optical element of mode 2, in mode 1, it is preferable that the apexes of the projections of the uneven layer are horizontal or convex. With this configuration, the optical properties of the uneven layer can be enhanced.

In the optical element of Aspect 3, in Aspect 1 or Aspect 2, it is preferable that the radius of curvature at the end of the convex portion of the uneven layer is smaller than the radius of curvature at the end of the concave portion of the uneven layer. With this configuration, the optical properties of the uneven layer can be enhanced.

In the optical element of Aspect 4, in any one of Aspects 1 to 3, the uneven layer has a maximum peak intensity B of 2900 cm ⁻¹ in the range of 100 cm ⁻¹ to 1000 cm ⁻¹ in Raman spectrum. The ratio of maximum peak intensity A (maximum peak intensity A/maximum peak intensity B) within the range of up to 3000 cm ⁻¹ is preferably 4.0 or less. When the ratio (maximum peak intensity A/maximum peak intensity B) is 4.0 or less, it is possible to reduce the content of the organic component in the uneven layer, further enhance the optical properties of the uneven layer, Moreover, damage to the uneven layer can be further suppressed.

In the optical element of Mode 5, in any one of Modes 1 to 4, it is preferable that the uneven layer has a refractive index of 1.60 or more. When the refractive index of the uneven layer is 1.60 or more, the reflection loss can be reduced, and the viewing angle of optical equipment such as goggles can be widened.

In the optical element of Mode 6, in any one of Modes 1 to 5, it is preferable that the uneven layer has an Abbe number of 5 or more and 35 or less.

In the optical element of mode 7, in any one of modes 1 to 6, when x is the refractive index of the uneven layer and y is the Abbe number of the uneven layer, the optical element is represented by the formula: y+50x The value is preferably 100 or more and 125 or less.

In the optical element of Aspect 8, in any one of Aspects 1 to 7, the inorganic nanoparticles are ZrO ₂ , BaTiO ₃ , TiO ₂ , Al ₂ O ₃ , Nb ₂ O ₅ , SiO ₂ and KTaO ₃ At least one inorganic nanoparticle selected from the group consisting of

In the optical element of Aspect 9, in any one of Aspects 1 to 8, the uneven layer includes inorganic nanoparticles A and inorganic nanoparticles having a smaller average particle diameter than the inorganic nanoparticles A as the inorganic nanoparticles. When the average particle diameter of the inorganic nanoparticles A is D _A nm and the average particle diameter of the inorganic nanoparticles B is D _B nm, the average particle diameter of the inorganic nanoparticles B is , the ratio (D _A /D _B ) to the average particle size of the inorganic nanoparticles A is preferably 1.5 or more and 20.0 or less.

In the optical element of aspect 10, in any one of aspects 1 to 9, it is preferable that the content of the inorganic nanoparticles is 10% by mass or more in 100% by mass of the uneven layer.

In the optical element of Mode 11, in any one of Modes 1 to 10, it is preferable that the optical transmittance at a wavelength of 500 nm is 55% or more.

In the optical element of Aspect 12, in any one of Aspects 1 to 11, the ratio h2/ It is preferred that h1 is between 0.9 and 1.3.

In the optical element of Aspect 13, in any one of Aspects 1 to 12, the translucent substrate is preferably a glass substrate.

The optical element of Aspect 14 is preferably used as an optical diffraction element in any one of Aspects 1 to 13.

In the optical element of Mode 15, in any one of Modes 1 to 14, it is preferable that the translucent substrate and the uneven layer are in direct contact.

In the optical element of Mode 16, in any one of Modes 1 to 15, it is preferable that the translucent substrate and the uneven layer are in close contact with each other via an adhesive layer.

In the optical element of Mode 17, in any one of Modes 1 to 16, it is preferable to have a thin film layer on the uneven layer.

In the optical element of aspect 18, in aspect 17, the thin film layer comprises _Y2O3 , _Al2O3 , _SiO2 , _MgO , _TiO2 , _CeO2 , _Bi2O3 _, _HfO2 _, Al, Ag, Au , Pt and carbon.

A method for manufacturing an optical element according to aspect 19 comprises the steps of disposing a material for an uneven layer on the surface of a member having unevenness on the surface to form a material layer for the uneven layer; disposing a translucent substrate on the surface opposite to the member; drying a material layer of the uneven layer disposed between the member and the translucent substrate; and a step of removing the.

In the method for manufacturing an optical element according to Aspect 20, in Aspect 19, in the step of forming the material layer of the uneven layer, after disposing the material of the uneven layer on the surface of the member, while degassing under reduced pressure, It is preferable to form a material layer for the uneven layer.

In the method of manufacturing an optical element of Aspect 21, in Aspect 19 or Aspect 20, in the step of disposing the translucent substrate, it is preferable to dispose the translucent substrate on a spacer placed on the member.

A method for manufacturing an optical element according to aspect 22 comprises the steps of disposing a material for an uneven layer on a main surface of a translucent substrate to form a material layer for the uneven layer; a step of disposing a member having an uneven surface on the surface opposite to the transparent substrate from the surface side; and a material layer of the uneven layer disposed between the member and the translucent substrate. It is characterized by comprising a step of drying and a step of removing the member.

A method for manufacturing an optical element according to aspect 23 includes the steps of: forming a material layer for an uneven layer on the surface of a member having unevenness on the surface; drying the material layer for the uneven layer to form an uneven layer; arranging a translucent substrate on the concavo-convex layer.

A method for manufacturing an optical element according to aspect 24 includes the steps of disposing a first material on the surface of a member having an uneven surface to form a material layer for a first uneven layer; drying the material layer to form a first uneven layer; disposing a second material on the first uneven layer to form a material layer for a second uneven layer; drying the material layer of the uneven layer 2 to form a second uneven layer; and placing a translucent substrate on the second uneven layer.

In the method for manufacturing an optical element according to Aspect 25, in any one of Aspects 19 to 24, the material of the uneven layer is a material containing inorganic nanoparticles, or a composite of a material containing inorganic nanoparticles and a sol-gel material. Materials are preferred.

In the method of manufacturing an optical element according to Aspect 26, in Aspect 25, it is preferable that the material of the uneven layer contains a resin.

In the method for manufacturing an optical element according to Aspect 27, in Aspect 26, it is preferable to burn off the resin by drying the material layer of the uneven layer at 250°C or higher.

In the method for manufacturing an optical element according to Aspect 28, in any one of Aspects 19 to 27, when the total height of the uneven layer is Ha and the height of the convex portion is H, the material layer of the uneven layer is dried. It is preferable that the ratio of the amount of H shrinkage to the amount of Ha shrinkage is 0.5 or less.

In the method for manufacturing an optical element of Aspect 29, in any one of Aspects 19 to 28, it is preferable to further include a step of transferring the material layer of the uneven layer to a film.

According to the present invention, it is possible to provide an optical element that has excellent optical properties and can suppress damage to the uneven layer. Further, according to the present invention, it is possible to provide a method for manufacturing the above optical element.

FIG. 1 is a perspective view schematically showing an optical element according to a first embodiment of the invention. FIG. 2 is a perspective view schematically showing an optical element according to a second embodiment of the invention. FIG. 3 is a perspective view schematically showing an optical element according to a third embodiment of the invention. 4A to 4D are cross-sectional views for explaining each step of the method for manufacturing an optical element according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view for explaining the height Ha of the uneven layer and the height H of the convex portion in the optical element of the present invention. 6A to 6D are cross-sectional views for explaining each step of the method for manufacturing an optical element according to the second embodiment of the present invention. 7A to 7D are cross-sectional views for explaining each step of the method for manufacturing an optical element according to the first modified example of the present invention. 8A to 8D are cross-sectional views for explaining each step of the method for manufacturing an optical element according to the second modification of the invention. 9(e) to 9(f) are cross-sectional views for explaining each step of the method for manufacturing an optical element according to the second modification of the invention.

A preferred embodiment will be described below. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments. Also, in each drawing, members having substantially the same function may be referred to by the same reference numerals.

In this specification, "to" in a numerical range means that the numerical values described at both ends are included as upper and lower limits. In this specification, unless otherwise specified, the refractive index of the light-transmitting substrate means the refractive index of the light-transmitting substrate at a wavelength of 530 nm, and the refractive index of the uneven layer means the wavelength of the uneven layer of 530 nm. means the refractive index at

[Optical element]
(First embodiment)
FIG. 1 is a perspective view schematically showing an optical element according to a first embodiment of the invention.

The optical element 10 shown in FIG. 1 includes a translucent substrate 1 and an uneven layer 2 having unevenness on the surface. The uneven layer 2 is arranged on the main surface of the translucent substrate 1 . The uneven layer 2 is arranged on one main surface (on the first main surface) of the translucent substrate 1 . The surface of the uneven layer 2 opposite to the translucent substrate 1 has unevenness.

The translucent substrate 1 is not particularly limited as long as it has practically sufficient light transmittance in the wavelength range used. The internal transmittance at a wavelength of 500 nm at a thickness of 10 mm of the translucent substrate 1 is preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, and particularly preferably 95% or more. Although the upper limit of the internal transmittance at a wavelength of 500 nm in the light-transmitting substrate 1 having a thickness of 10 mm is not particularly limited, it may be, for example, 100% or less or 99% or less.

Examples of the translucent substrate 1 include glass substrates and resin substrates. From the viewpoint of further enhancing the weather resistance, the translucent substrate 1 is preferably a glass substrate.

The refractive index of the translucent substrate 1 is preferably 1.60 or higher, more preferably 1.70 or higher, even more preferably 1.80 or higher, still more preferably 1.90 or higher, and even more preferably 1.95 or higher. , particularly preferably 1.99 or more. The refractive index of the translucent substrate 1 is preferably 2.30 or less, more preferably 2.20 or less, even more preferably 2.10 or less, and particularly preferably 2.00 or less. When the refractive index of the translucent substrate 1 is equal to or higher than the above lower limit, the amount of light incident on the translucent substrate 1 can be increased, and the viewing angle of optical equipment such as goggles can be widened. Note that the refractive index of the translucent substrate 1 may be 1.90 or less, 1.80 or less, 1.70 or less, or 1.65 or less. Well, it may be 1.60 or less.

The refractive index of the translucent substrate 1 is the refractive index at a wavelength of 530 nm, and can be measured with a V-block refractometer.

The Abbe number of the translucent substrate 1 is preferably 5 or more, more preferably 7 or more, still more preferably 9 or more, still more preferably 10 or more, still more preferably 12 or more, even more preferably 14 or more, and particularly preferably is 15 or more, preferably 40 or less, more preferably 36 or less, even more preferably 34 or less, still more preferably 32 or less, still more preferably 30 or less, even more preferably 28 or less, particularly preferably 26 or less be. If the Abbe number of the light-transmitting substrate 1 is equal to or higher than the above lower limit, SiO ₂ , B ₂ O ₃ , Na ₂ O, K ₂ O, Li ₂ O, etc. in the glass when the light-transmitting substrate 1 is a glass substrate. It is no longer necessary to reduce the content of, and the liquidus temperature can be kept low. When the Abbe number of the translucent substrate 1 is equal to or less than the above upper limit, when the translucent substrate 1 is a glass substrate, La ₂ O ₃ , Nb ₂ O ₅ , and TiO _{2 ,} which are components that increase the refractive index in the glass, It is no longer necessary to reduce the content, and as a result, the refractive index of the translucent substrate 1 can be maintained high.

The Abbe number νd of the translucent substrate 1 is obtained from the refractive index nd at a wavelength of 587.6 nm (d-line), the refractive index nC at a wavelength of 656.3 nm (C-line), and the refractive index nF at a wavelength of 486 nm (F-line). It is obtained by the formula: νd=(nd−1)/(nF−nC). The refractive index nd, the refractive index nC, and the refractive index nF for determining the Abbe number of the translucent substrate 1 can be measured with a V-block refractometer.

The translucent substrate 1 is Si--B--La--Nb--Ti based glass, Bi--Te--B based glass, or Si--B--RO based glass (RO is MgO, CaO, BaO, SrO or ZnO). Preferably. Specifically, the Si-B-La-Nb-Ti-based glass contains 1 to 21% SiO ₂ , 5 to 30% B ₂ O _{3 ,} 0 to 5% ZnO, and 1 to 15% ZrO ₂ in mass %. , La ₂ O ₃ 20-50%, Gd ₂ O ₃ 0-16%, Nb ₂ O ₅ 3-40%, Ta ₂ O ₅ 0-5%, TiO ₂ 5-25%, and a lead component, It is preferable not to contain an arsenic component and an F component. The Bi--Te--B glass preferably contains 40 to 90% by mass of Bi ₂ O ₃ , 1 to 30% by mass of B ₂ O ₃ and 0.1 to 19% by mass of TeO ₂ . In addition, the Si-B-RO glass contains, in mass %, SiO ₂ 5 to 50%, B ₂ O ₃ 1 to 30%, Al ₂ O ₃ 0 to 10%, ZnO 0 to 20%, CaO 0 to 20%. %, MgO 0-20%, SrO 0-20%, MgO + CaO + BaO + SrO + ZnO (total content of MgO, CaO, BaO, SrO and ZnO) 1-30%, Na ₂ O 1-20%, ZrO _0-10 % , La ₂ O ₃ 0-20%, Sb ₂ O ₃ 0-1%, and SnO ₂ 0-1%. In addition, "not containing a lead component, an arsenic component, and an F component" means that the content of each of the lead component, the arsenic component, and the F component is 0.1% by mass or less.

The thickness of the translucent substrate 1 is preferably 0.01 mm or more, more preferably 0.50 mm or more, and preferably 10.0 mm or less, more preferably 2.0 mm or less. Mechanical strength can be improved as the thickness of the translucent board|substrate 1 is more than the said minimum. When the thickness of the light-transmitting substrate 1 is equal to or less than the above upper limit, it is possible to suppress a decrease in light transmittance and further improve the optical properties.

In this specification, the uneven layer is a layer having a plurality of protrusions or a plurality of recesses. The uneven layer preferably has a periodic structure with a plurality of protrusions or a plurality of recesses on its surface. The uneven layer has an uneven surface. The surface of the uneven layer opposite to the light-transmitting substrate side is an uneven surface.

The uneven layer 2 contains inorganic nanoparticles. Therefore, the refractive index of the concavo-convex layer 2 can be increased, and therefore the optical properties of the optical element 10 can be increased. In addition, since the uneven layer 2 contains inorganic nanoparticles, the structure of the uneven layer 2 is densified. Furthermore, the adhesion between the translucent substrate 1 and the uneven layer 2 can be further enhanced. Only one kind of the inorganic nanoparticles may be used, or two or more kinds thereof may be used in combination.

The average particle size of the inorganic nanoparticles is preferably 200 nm or less, more preferably 100 nm or less, still more preferably 50 nm or less, even more preferably 30 nm or less, and particularly preferably 20 nm or less. When the average particle diameter is equal to or less than the upper limit, the optical properties of the uneven layer 2, specifically, the refractive index and the transmittance can be further improved, and the strength of the uneven layer 2 can be further increased. can be done. If the average particle size exceeds the upper limit, the optical properties of the uneven layer 2, specifically, the refractive index and the transmittance, are reduced. Deterioration of the dispersion in the water causes sedimentation and separation, and as a result, there is a possibility that the formation of the uneven layer 2 becomes difficult. The average particle size of the inorganic nanoparticles is preferably 0.01 nm or more, more preferably 0.1 nm or more, even more preferably 0.5 nm or more, still more preferably 1.0 nm or more, and even more preferably 1.0 nm or more. 5 nm or more, particularly preferably 2.0 nm or more. If the average particle diameter is less than the above lower limit, shrinkage during drying increases in the step of producing the uneven layer 2, which makes the uneven layer 2 more likely to crack or makes it difficult to form a dense uneven layer 2. There is a risk of

The average particle size of the inorganic nanoparticles means the volume average particle size (D50). The average particle size of the inorganic nanoparticles can be measured by a dynamic light scattering method.

The inorganic nanoparticles are preferably inorganic _oxide nanoparticles, selected from the group consisting of titanium compounds such as _ZrO2 _, _TiO2 and _BaTiO3 , _Al2O3 , _Nb2O5 , _SiO2 and _KTaO3 . and at least one inorganic nanoparticle selected from the group consisting of ZrO ₂ , BaTiO ₃ , TiO ₂ , Al ₂ O ₃ , Nb ₂ O ₅ , SiO ₂ and KTaO ₃ and at least one inorganic nanoparticle selected from the group consisting of ZrO ₂ , BaTiO ₃ , TiO ₂ , Al ₂ O ₃ , Nb ₂ O ₅ and SiO ₂ is more preferred, and at least one inorganic nanoparticle selected from the group consisting of ZrO ₂ , TiO ₂ , Al ₂ O ₃ and SiO ₂ is particularly preferred. In this case, the effects of the present invention can be exhibited more effectively.

The content of the inorganic nanoparticles in the uneven layer 2 (out of 100% by mass of the uneven layer) is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and particularly preferably 50% by mass. % or more. When the content of the inorganic nanoparticles is at least the lower limit, the effects of the present invention can be exhibited more effectively. From the viewpoint of improving the moldability of the uneven layer 2, the upper limit of the content of the inorganic nanoparticles in the uneven layer 2 (out of 100% by mass of the uneven layer) may be 99% by mass or less, or 98% by mass. or less, or 95% by mass or less. In addition, from the viewpoint of suppressing deformation of the material layer 2X of the uneven layer, which will be described later, the content of the inorganic nanoparticles in the uneven layer 2 (out of 100% by mass of the uneven layer) is preferably 50% by mass or more. , More preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 75% by mass or more, still more preferably 80% by mass or more, 90% by mass or more is more preferably 95% by mass or more, and particularly preferably 99% by mass or more. When the content of inorganic nanoparticles is large, the content of other components such as resin is relatively decreased, so that deformation (shrinkage) during drying can be easily suppressed. In addition, from the viewpoint of particularly increasing the refractive index of the uneven layer 2 by removing the resin component by burning off, which will be described later, the content of the inorganic nanoparticles in the uneven layer 2 (out of 100% by mass of the uneven layer) is 90% by mass. % or more, more preferably 95 mass % or more, still more preferably 99 mass % or more, and particularly preferably 100 mass %.

The uneven layer 2 preferably contains inorganic nanoparticles A and inorganic nanoparticles B having an average particle diameter smaller than that of the inorganic nanoparticles A as the inorganic nanoparticles. By using a combination of inorganic nanoparticles having different average particle diameters, the voids between the inorganic nanoparticles in the uneven layer 2 can be reduced, and the inorganic nanoparticles can be highly packed. Therefore, the refractive index of the uneven layer 2 can be further improved, and the optical properties of the optical element can be further improved.

When the average particle diameter of the inorganic nanoparticles A is D _A nm and the average particle diameter of the inorganic nanoparticles B is D _B nm, the average particle diameter of the inorganic nanoparticles A with respect to the average particle diameter of the inorganic nanoparticles B The diameter ratio (D _A /D _B ) is preferably 1.5 or more, more preferably 2.0 or more, still more preferably 3.0 or more, preferably 20.0 or less, more preferably 10.0. 6.0 or less, more preferably 6.0 or less. When the ratio (D _A /D _B ) is equal to or higher than the lower limit and equal to or lower than the upper limit, the inorganic nanoparticles in the uneven layer 2 can be highly filled, so that the optical properties of the optical element can be further improved. can be done. Moreover, aggregation of inorganic nanoparticles can be effectively suppressed when the ratio (D _A /D _B ) is equal to or less than the upper limit.

The uneven layer 2 has a plurality of protrusions 21 . Note that the uneven layer 2 can also be viewed as having a plurality of recesses 22 .

In the present embodiment, the projections 21 are linear projections. In the uneven layer 2, a plurality of protrusions 21 are provided parallel to each other. In other words, in the present embodiment, the uneven layer 2 is a lattice groove with a rectangular cross section. The shape of the uneven layer 2 is not limited to the above. For example, the cross-sectional shape may be a sinusoidal or sawtooth lattice groove.

The height H of the protrusions 21 is preferably 10 nm or more, more preferably 25 nm or more, still more preferably 30 nm or more, still more preferably 50 nm or more, particularly preferably 75 nm or more, and preferably 5 μm or less, more preferably 2 μm or less. , more preferably 1 μm or less, more preferably 800 nm or less, and particularly preferably 600 nm or less. When the height H of the convex portion 21 is equal to or more than the lower limit and equal to or less than the upper limit, the optical properties can be further improved. Further, if the height H of the projections 21 is equal to or less than the upper limit, damage to the uneven layer 2 can be effectively suppressed. Note that the height H of the protrusion 21 corresponds to the depth of the recess 22 . The height H of the convex portion 21 means the height h1 at the end portion of the convex portion 21 and the height h2 at the central portion of the convex portion 21, which will be described later, whichever is larger.

The width W of the convex portion 21 is preferably 10 nm or more, more preferably 25 nm or more, still more preferably 50 nm or more, particularly preferably 75 nm or more, preferably 5 μm or less, more preferably 1 μm or less, further preferably 800 nm or less. Particularly preferably, it is 600 nm or less. When the width W of the convex portion 21 is equal to or more than the lower limit and equal to or less than the upper limit, the optical characteristics can be further improved.

The period P in the periodic structure of the uneven layer 2 is preferably 10 nm or more, more preferably 50 nm or more, still more preferably 100 nm or more, particularly preferably 200 nm or more, preferably 5 μm or less, more preferably 1 μm or less, and even more preferably. 800 nm or less, particularly preferably 600 nm or less. When the period P in the periodic structure of the concavo-convex layer 2 is equal to or more than the lower limit and equal to or less than the upper limit, the optical properties can be further improved.

The minimum thickness of the uneven layer 2 is preferably 10 nm or more, more preferably 50 nm or more, still more preferably 100 nm or more, particularly preferably 500 nm or more, preferably 10000 nm or less, more preferably 5000 nm or less, still more preferably 2500 nm or less, Especially preferably, it is 1000 nm or less. When the minimum thickness of the concavo-convex layer 2 is equal to or more than the lower limit and equal to or less than the upper limit, the optical properties can be further enhanced.

The convex portion 21 preferably has a horizontal or convex top. Thereby, the optical characteristics of the concavo-convex layer 2 can be further improved. Note that the convex portion 21 having a horizontal or convex top portion is produced by, for example, a method for manufacturing an optical element according to the first embodiment of the present invention and a method for manufacturing an optical element according to the first modified example of the present invention, which will be described later. It is easy to form by using the method or the method for manufacturing an optical element according to the second modification of the present invention.

The ratio h2/h1 of the height h1 at the end of the protrusion 21 of the uneven layer 2 and the height h2 at the center of the protrusion 21 is preferably 0.5 to 1.5, more preferably 0.9. ~1.3, more preferably 0.95 to 1.3, still more preferably 1 to 1.3, even more preferably greater than 1 to 1.3, particularly preferably 1.01 to 1.2. When h2/h1 is within the above range, it becomes easier to obtain the concavo-convex layer 2 having desired optical properties. From the viewpoint of further enhancing optical properties, h2/h1 is preferably greater than 1 to 1.3, more preferably 1.01 to 1.21. The height h1 at the ends of the projections 21 and the height h2 at the center of the projections 21 can be measured by observing the cross section of the uneven layer 2 using an electron microscope, for example.

The radius of curvature at the end of the projection 21 is preferably smaller than the radius of curvature at the end of the recess 22 . Thereby, the optical characteristics of the concavo-convex layer 2 can be further enhanced.

The absolute value of the difference between the refractive index of the translucent substrate 1 and the refractive index of the uneven layer 2 is 0.20 or less. More specifically, the absolute value of the difference between the refractive index of the translucent substrate 1 at a wavelength of 530 nm and the refractive index of the uneven layer 2 at a wavelength of 530 nm is 0.20 or less. In the present invention, since the absolute value of the difference between the refractive index of the light-transmitting substrate 1 and the refractive index of the uneven layer 2 is small, light loss due to light scattering at the interface between the light-transmitting substrate 1 and the uneven layer 2 is suppressed. and thus the optical properties of the optical element 10 can be enhanced. Moreover, since the absolute value of the difference is 0.20 or less, the reflection loss can be reduced, and the viewing angle of optical equipment such as goggles can be widened.

The absolute value of the difference between the refractive index of the translucent substrate 1 and the refractive index of the uneven layer 2 is preferably 0.15 or less, more preferably 0.1 or less. When the absolute value of the difference is equal to or less than the upper limit, the optical properties of the optical element 10 can be further enhanced. Although the lower limit of the absolute value of the difference is not particularly limited, it may be, for example, 0 or more, or 0.01 or more.

The refractive index of the uneven layer 2 may be larger or smaller than the refractive index of the translucent substrate 1 . The refractive index of the uneven layer 2 may be the same as the refractive index of the translucent substrate 1 .

The refractive index of the uneven layer 2 is preferably 1.60 or higher, more preferably 1.70 or higher, still more preferably 1.80 or higher, and particularly preferably 1.90 or higher. When the refractive index of the uneven layer 2 is equal to or higher than the above lower limit, the viewing angle of optical equipment such as goggles can be widened. Although the upper limit of the refractive index of the uneven layer 2 is not particularly limited, it may be, for example, 2.4 or less, or 2.3 or less.

The Abbe number of the uneven layer 2 is preferably 5 or more, more preferably 7 or more, still more preferably 9 or more, particularly preferably 10 or more, preferably 35 or less, more preferably 30 or less, and even more preferably 25 or less. , more preferably 20 or less, even more preferably 18 or less, particularly preferably 16 or less, most preferably 15 or less. When the Abbe number of the uneven layer 2 is equal to or more than the above lower limit and equal to or less than the above upper limit, the absolute value of the difference between the refractive index of the translucent substrate 1 and the refractive index of the uneven layer 2 can be easily reduced, and the optical properties of the optical element can be improved. can be further enhanced. When the Abbe number of the uneven layer 2 is less than the above lower limit, the refractive index of the uneven layer 2 tends to be higher than the refractive index of the translucent substrate 1 . Further, when the Abbe number of the uneven layer 2 exceeds the above upper limit, the refractive index of the uneven layer 2 tends to be smaller than the refractive index of the translucent substrate 1 .

The refractive index of the uneven layer 2 can be obtained by measuring the refractive index at a wavelength of 530 nm using a spectroscopic ellipsometer. Moreover, the Abbe number of the uneven layer 2 can be obtained using a spectroscopic ellipsometer.

Let x be the refractive index of the uneven layer 2 (refractive index at a wavelength of 530 nm), and y be the Abbe number of the uneven layer 2 . At this time, the value represented by the formula: y+50x is preferably 100 or more, preferably 125 or less, more preferably 120 or less, and even more preferably 115 or less. When the value represented by the formula: y+50x is equal to or more than the lower limit and equal to or less than the upper limit, the refractive index curves of the translucent substrate 1 and the uneven layer 2 tend to intersect in the wavelength range of 400 nm to 800 nm. If the value represented by the above formula: y+50x is larger than 125, matching of the refractive index and Abbe number between the uneven layer 2 and the translucent substrate 1 tends to be difficult.

The refractive index curve of the translucent substrate 1 and the refractive index curve of the uneven layer 2 preferably intersect in the wavelength range of 400 nm to 780 nm. The wavelength range at which the refractive index curve of the translucent substrate 1 and the refractive index curve of the concavo-convex layer 2 intersect is preferably 410 nm to 650 nm, more preferably 420 nm to 600 nm, still more preferably 430 nm to 550 nm, and particularly preferably 440 nm. ~500 nm. When the refractive index curves intersect in the above wavelength range, it is easy to match the refractive indices, and the reflection loss can be effectively suppressed.

The above refractive index curve is a curve showing the relationship between the wavelength and the refractive index, where the horizontal axis is the wavelength and the vertical axis is the refractive index.

The uneven layer 2 has a ratio of the maximum peak intensity A within the range of 2900 cm ⁻¹ to 3000 cm ⁻¹ to the maximum peak intensity B within the range of 100 cm ⁻¹ to 1000 cm ⁻¹ in the Raman spectrum (maximum peak intensity A /maximum peak intensity B) is preferably 4.0 or less, preferably 3.5 or less, more preferably 3.0 or less, and even more preferably 2.5 or less , is more preferably 2.0 or less, even more preferably 1.5 or less, and particularly preferably 1.0 or less. It means that the smaller the ratio (maximum peak intensity A/maximum peak intensity B), the smaller the content of the organic component in the uneven layer 2 . When the ratio (maximum peak intensity A/maximum peak intensity B) is equal to or less than the upper limit, the light incident on the uneven layer 2 is effectively prevented from being diffusely reflected in the uneven layer 2 by the organic component in the uneven layer 2. can be suppressed to As a result, the optical properties of the uneven layer 2 can be enhanced, and damage to the uneven layer 2 caused by a decrease in mechanical strength due to the organic component in the uneven layer 2 can be suppressed.

The ratio (maximum peak intensity A/maximum peak intensity B) is measured, for example, under the conditions described in Examples below. The peak position of the maximum peak intensity B changes depending on the component. The peak positions are ZrO ₂ 500±100 cm ⁻¹ , TiO ₂ 200±100 cm ⁻¹ , SiO ₂ 400±100 cm ⁻¹ , Nb ₂ O ₅ 700±100 cm ⁻¹ , Al ₂ O ₃ 600±100 cm ⁻¹ , BaTiO _{3 .} 400±100 cm ⁻¹ .

The average thermal expansion coefficient of the uneven layer 2 at 30° C. to 100° C. is preferably 50×10 ⁻⁷ /° C. or higher, more preferably 70×10 ⁻⁷ /° C. or higher, and preferably 150×10 ⁻⁷ /° C. or lower. More preferably, it is 120×10 ⁻⁷ /° C. or less.

The absolute value of the difference between the average thermal expansion coefficient of the translucent substrate 1 at 30° C. to 100° C. and the average thermal expansion coefficient of the uneven layer 2 at 30° C. to 100° C. is preferably 50×10 ⁻⁷ /° C. or less, More preferably, it is 25×10 ⁻⁷ /° C. or less. When the absolute value of the difference is equal to or less than the upper limit, the adhesion between the translucent substrate 1 and the uneven layer 2 can be further enhanced. Although the lower limit of the absolute value of the difference is not particularly limited, it may be, for example, 1×10 ⁻⁷ /° C. or more. If the absolute value of the difference exceeds the upper limit, the thermal expansion coefficients of the light-transmitting substrate 1 and the uneven layer 2 cannot be matched, and the residual stress exerted on the uneven layer 2 causes the light-transmitting substrate 1 There is a risk of peeling from. Therefore, the residual stress generated in the translucent substrate 1 is preferably 10 MPa or less, more preferably 5 MPa or less, even more preferably 3 MPa or less, and particularly preferably 1 MPa or less, regardless of tensile stress or compressive stress. Although the lower limit of the residual stress is not particularly limited, it may be, for example, 0.01 MPa or more.

The translucent substrate 1 and the uneven layer 2 are preferably in direct contact. Thereby, the adhesion between the translucent substrate 1 and the concavo-convex layer 2 can be enhanced, and the optical characteristics of the optical element 10 can be further enhanced. Further, the translucent substrate 1 and the uneven layer 2 may be in close contact with each other via an adhesive layer (not shown). This configuration can be obtained, for example, by bonding the concavo-convex layer 2 and the translucent substrate 1 together with an adhesive.

The type of adhesive is not particularly limited, and organic adhesives and inorganic adhesives can be used. From the viewpoint of further enhancing the optical properties of the optical element 10, the absolute value of the difference between the refractive index of the adhesive and the refractive index of the translucent substrate 1 is preferably 0.15 or less, particularly 0.10 or less. is preferred. Although the lower limit of the absolute value of the difference is not particularly limited, it may be, for example, 0.001 or more. The absolute value of the difference between the refractive index of the adhesive and the refractive index of the concavo-convex layer 2 is preferably 0.15 or less, more preferably 0.10 or less. When the absolute value of the difference is equal to or less than the upper limit, the optical properties of the optical element 10 can be further enhanced. Although the lower limit of the absolute value of the difference is not particularly limited, it may be, for example, 0.001 or more.

The thickness of the adhesive layer is preferably 500 nm or less, more preferably 400 nm or less, and even more preferably 300 nm or less. If the thickness of the adhesive layer is too large, the light transmittance of the optical element 10 tends to decrease. The lower limit of the thickness of the adhesive layer may be, for example, 10 nm or more.

The optical element 10 may have a thin film layer (not shown) on the uneven layer 2 . The thin film layer may be a single layer film or a multilayer film. The thin film layer may be, for example, a metal reflective film, an antireflection film, or a protective film. For example, by providing a metal reflective film, the reflection effect of the entire optical element 10 can be enhanced, and the light guide effect when the optical element 10 is used as a light guide plate can be enhanced. For example, by providing an antireflection film, the amount of light incident on the uneven layer 2 can be increased. For example, by providing a protective film, it becomes easier to suppress damage to the uneven layer 2 .

The thin film layer is for example selected from the group consisting of _Y2O3 , _Al2O3 , _SiO2 , _MgO , _TiO2 , _CeO2 , _Bi2O3 , _HfO2 _, Al, Ag, Au, Pt _and carbon. It is preferably made of at least one material that Also, the thin film layer may be formed from a resin material such as an olefin resin. Alternatively, diamond-like carbon (DLC) may be used as the carbon material.

The thickness of each thin film layer is preferably 10 nm to 1000 nm, more preferably 10 nm to 800 nm, even more preferably 30 nm to 500 nm, and particularly preferably 50 nm to 400 nm. If the thickness per layer is too small, it may become difficult to obtain desired optical properties. On the other hand, if the thickness of each layer is too large, the stress applied to the interface between the thin film layer and the uneven layer 2 increases, and the adhesion of the thin film layer tends to decrease. When the thin film layer is a metal reflective film, the thickness of each thin film layer is preferably 10 nm to 400 nm, more preferably 30 nm to 350 nm, even more preferably 50 nm to 300 nm. preferable.

Examples of film formation methods include vacuum deposition, ion plating, and sputtering.

The light transmittance of the optical element 10 at a wavelength of 300 nm to 800 nm is preferably 55% or higher, more preferably 60% or higher, and even more preferably 65% or higher. When the light transmittance is equal to or higher than the lower limit, the optical properties can be further improved. Although the upper limit of the light transmittance of the optical element 10 at a wavelength of 300 nm to 800 nm is not particularly limited, it may be, for example, 100% or less, or 99% or less.

The light transmittance of the optical element 10 at a wavelength of 500 nm is preferably 55% or higher, more preferably 60% or higher, and even more preferably 65% or higher. When the light transmittance is equal to or higher than the lower limit, the optical properties can be further improved. Although the upper limit of the light transmittance of the optical element 10 at a wavelength of 500 nm is not particularly limited, it may be, for example, 100% or less, or 99% or less.

The light transmittance of the optical element 10 at a wavelength of 450 nm is preferably 55% or higher, more preferably 60% or higher, and even more preferably 65% or higher. When the light transmittance is equal to or higher than the lower limit, the optical properties can be further improved. Although the upper limit of the light transmittance of the optical element 10 at a wavelength of 450 nm is not particularly limited, it may be, for example, 100% or less, or 99% or less.

The light transmittance of the optical element 10 at wavelengths of 300 nm to 800 nm, 500 nm and 450 nm can be measured using a transmittance meter (eg, "V-670" manufactured by JASCO Corporation). For example, the above-described light transmittance can be measured by letting light enter the optical element 10 from the side of the transparent substrate 1 at an incident angle of 0°.

The optical element 10 is suitably used as an optical diffraction element. Also, the optical element 10 can be suitably used as a light guide plate provided with a diffraction structure. The optical diffraction element and the light guide plate are components of wearable image display devices selected from glasses with a projector, eyeglass-type or goggle-type displays, virtual reality (VR) or augmented reality (AR) display devices, and virtual image display devices. It is particularly suitable as

(Second embodiment)
FIG. 2 is a perspective view schematically showing an optical element according to a second embodiment of the invention.

The optical element 10A shown in FIG. 2 includes a translucent substrate 1 and an uneven layer 2A having unevenness on the surface. The optical element 10 shown in FIG. 1 differs from the optical element 10A shown in FIG. 2 in the shape of the concavo-convex layer.

In addition, unless otherwise specified, other points such as the preferred configuration of the optical element 10A are the same as other points such as the preferred configuration described in the section of the first embodiment.

In the optical element 10A, the uneven layer 2A has a plurality of columnar protrusions 21A. A plurality of convex portions 21A are provided periodically. However, the shape of the convex portion 21A is not particularly limited, and may be, for example, a polygonal columnar shape or a hemispherical shape.

Also in the second embodiment, the uneven layer 2A contains inorganic nanoparticles, and the absolute value of the difference between the refractive index of the translucent substrate 1 and the refractive index of the uneven layer 2A is 0.20 or less. It is excellent in optical properties and can suppress breakage of the uneven layer 2A.

The height H of the convex portion 21A is preferably 10 nm or more, more preferably 25 nm or more, still more preferably 30 nm or more, still more preferably 50 nm or more, particularly preferably 75 nm or more, and preferably 5 μm or less, more preferably 2 μm. Below, it is more preferably 1 μm or less, still more preferably 800 nm or less, and particularly preferably 600 nm or less. When the height H of the convex portion 21A is equal to or more than the lower limit and equal to or less than the upper limit, the optical properties can be further improved. Further, when the height H of the convex portion 21A is equal to or less than the above upper limit, it is possible to effectively suppress damage to the uneven layer 2A.

(Third embodiment)
FIG. 3 is a perspective view schematically showing an optical element according to a third embodiment of the invention.

The optical element 10B shown in FIG. 3 includes a translucent substrate 1 and an uneven layer 2B having unevenness on the surface. The optical element 10 shown in FIG. 1 differs from the optical element 10B shown in FIG. 3 in the shape of the concavo-convex layer.

In addition, unless otherwise specified, other points such as the preferred configuration of the optical element 10B are the same as other points such as the preferred configuration described in the section of the first embodiment.

In the optical element 10B, the uneven layer 2B has a plurality of cylindrical recesses 22B. A plurality of recesses 22B are provided periodically. However, the shape of the recess 22B is not particularly limited, and may be, for example, a polygonal columnar shape or a hemispherical shape.

Also in the third embodiment, the uneven layer 2B contains inorganic nanoparticles, and the absolute value of the difference between the refractive index of the translucent substrate 1 and the refractive index of the uneven layer 2B is 0.20 or less. It is excellent in optical characteristics and can suppress breakage of the uneven layer 2B.

The depth D of the concave portion 22B is preferably 10 nm or more, more preferably 25 nm or more, still more preferably 30 nm or more, even more preferably 50 nm or more, particularly preferably 75 nm or more, and preferably 5 μm or less, more preferably 2 μm or less. , more preferably 1 μm or less, still more preferably 800 nm or less, and particularly preferably 600 nm or less. When the depth D of the concave portion 22B is equal to or more than the lower limit and equal to or less than the upper limit, the optical properties can be further improved.

<Other details of the optical element>
In the first to third embodiments, the configuration in which the uneven layer is arranged on one main surface of the translucent substrate has been described. An uneven layer may be arranged thereon. That is, the optical element of the present invention includes a light-transmitting substrate, an uneven layer (first uneven layer) disposed on a first main surface of the light-transmitting substrate, and a first uneven layer of the light-transmitting substrate. and an uneven layer (second uneven layer) disposed on the second main surface. In this case, the type of inorganic nanoparticles contained in the first uneven layer and the type of inorganic nanoparticles contained in the second uneven layer may be the same or different. Further, the shape of the first uneven layer and the shape of the second uneven layer may be the same or different.

[Method for manufacturing an optical element]
The optical element according to the present invention can be suitably manufactured using, for example, nanoimprint technology.

An example of the method for manufacturing an optical element according to the present invention will be described in detail below.

(First embodiment)
4A to 4D are cross-sectional views for explaining each step of the method for manufacturing an optical element according to the first embodiment of the present invention. 4A to 4D are cross-sectional views for explaining each step of the method of manufacturing the optical element 10 shown in FIG. The method for manufacturing an optical element according to the present embodiment includes steps of forming a material layer for the uneven layer by disposing a material for the uneven layer on the surface of a member having unevenness on the surface; placing a translucent substrate on the surface opposite the side; drying the material layer of the uneven layer disposed between the member and the translucent substrate; removing the member; Prepare.

<Step of Forming Material Layer for Concavo-convex Layer>
First, a member 50 having an uneven surface is prepared. In this embodiment, the member 50 is a silicone resin member. A material for the uneven layer is placed on the uneven surface of the member 50 . In this embodiment, the dispenser 60 is used to dispose the material of the uneven layer on the uneven surface of the member 50 . In this manner, the material layer 2X of the uneven layer can be formed on the uneven surface of the member 50 (FIG. 4A). Note that the member 50 is not limited to a silicone resin member, and for example, a UV curable resin film having unevenness on the surface may be used.

From the viewpoint of good formation of the uneven layer, the material of the uneven layer is preferably a material containing inorganic nanoparticles or a composite material of a material containing inorganic nanoparticles and a sol-gel material. The inorganic nanoparticles described above can be used as the inorganic nanoparticles.

As the sol-gel material, metal alkoxides and non-metal alkoxides can be used as precursors. Examples of metal alkoxides include alumina acid, titanate, zirconate, and niobic acid. Examples of non-metal alkoxides include alkoxysilanes and alkoxyborates. Examples of alkoxysilanes include tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS). As the alkoxy group of alkoxysilanes, ethyl group, methoxy group, propoxy group, butoxy group or other long-chain hydrocarbon alkoxy groups are used.

From the viewpoint of facilitating the handling of the material of the uneven layer and improving the moldability of the material layer 2X of the uneven layer, it is preferable that the material of the uneven layer contains a resin. As the resin, it is preferable to use a photocurable resin. For example, it is preferable to use an acrylic monomer. More specifically, acrylic bisphenol A glycerolate dimethacrylate, esters with acrylic acid (OPPEOA), bisphenol A ethoxylate diacrylates, bisphenol A propoxylate diacrylate, bisphenol F ethoxylate (2EO/ phenol) diacrylate, bisphenol A glycerolate diacrylates, bisphenol A ethoxylate dimethacrylate, ethoxylated (4) bisphenol A diacrylate (SR-601), bisphenol A ethoxylate diacrylate (SR-349), tris ( 2-acryloyloxy)ethyl}isocyanurate, tricyclodecanedimethanol diacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, cresol novolac epoxy acrylate (CN112C60), benzyl methacrylate (BMA), Benzyl acrylate, trimethylolpropane triacrylate (TMPTA), trimethylolpropane ethoxylate (1EO/OH) methyl ether diacrylate, 1,6-hexanediol diacrylate (HDDA, SR238B), tri(ethylene glycol) Acrylates selected from diacrylates, ethylene glycol diacrylates, poly(ethylene glycol) diacrylates, glycerol 1,3-diglycerolate diacrylates, di(ethylene glycol) diacrylates, and combinations thereof are preferred.

When the material of the uneven layer contains a photocurable resin, it is preferable to add a polymerization initiator to the material of the uneven layer. In particular, it is preferable to add a thiol in order to obtain high curability. Curing by UV irradiation and drying by heating may be used in combination.

Examples of polymerization initiators include 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenylketone, acetophenone, benzophenone, xanthone, fluorenone, bezaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methyl Acetophenone, Michler's ketone and the like can be mentioned. These polymerization initiators can be used singly or in combination of two or more. Further, these polymerization initiators are preferably contained at 0.001% by mass to 5% by mass, respectively, in terms of mass% with respect to the monofunctional compound and the polyfunctional compound, and each is 0.01% by mass. More preferably, it is contained in an amount of up to 1% by mass. A sensitizer such as an amine compound may be used in combination as necessary.

The material of the uneven layer preferably contains a solvent. Examples of the solvent include organic solvents such as ethanol, butanol, ethoxylated bisphenol A diacrylate (PGMEA), and water.

It should be noted that, in this step, it is preferable to form the material layer 2X of the uneven layer while degassing under reduced pressure after placing the material of the uneven layer on the uneven surface of the member 50 . This makes it easier for the bubbles contained in the material of the uneven layer to disappear. As a result, the voids between the inorganic nanoparticles in the resulting uneven layer 2 are reduced, and the inorganic nanoparticles in the uneven layer 2 can be highly packed, that is, the refractive index can be increased, and the strength of the uneven layer 2 can be improved.

The method of arranging the material of the uneven layer is not limited to the dispenser 60. For example, the material of the uneven layer may be arranged by spin coating. By using spin coating, it becomes easier to form the uneven layer material layer 2X having a uniform thickness. Alternatively, the material of the uneven layer may be arranged by using a spray. Using a spray facilitates effective deposition of the inorganic nanoparticles. As a result, the inorganic nanoparticles in the material layer 2X of the concavo-convex layer adhere to each other, and the inorganic nanoparticles in the concavo-convex layer 2 can be highly packed.

<Step of Arranging Translucent Substrate>
Next, the translucent substrate 1 is arranged on the surface of the material layer 2X of the concavo-convex layer opposite to the member 50 side (FIG. 4(b)). From the viewpoint of adjusting the thickness of the uneven layer 2 to be obtained, it is preferable to dispose the translucent substrate 1 on a spacer placed on the member 50 . As a result, it is possible to prevent the accuracy of the uneven shape from deteriorating due to shrinkage due to drying when the depth of the recesses of the uneven layer 2 is deep and when the width of the recesses is narrow. When the depth of the concave portion is shallow and the width of the concave portion is wide, it is possible to improve the accuracy of the concave-convex shape also by the method of the second embodiment described later.

After disposing the translucent substrate 1, it is preferable to apply a load to the translucent substrate 1, the material layer 2X of the concavo-convex layer, and the member 50. This makes it easier to stabilize the shape of the uneven layer 2 . In addition, it becomes easier to improve the adhesion between the translucent substrate 1 and the uneven layer 2 . The load is, for example, preferably 10 kgf or more, more preferably 20 kgf or more, even more preferably 30 kgf or more, still more preferably 40 kgf or more, and particularly preferably 50 kgf or more. Although the upper limit of the load is not particularly limited, it may be 300 kgf or less, for example.

<Step of drying the material layer of the concavo-convex layer>
Next, the uneven layer material layer 2X disposed between the member 50 and the translucent substrate 1 is dried, and the uneven layer material layer 2X is cured. More specifically, the material layer 2X for the uneven layer is dried by heating to harden the material layer 2X for the uneven layer. The drying evaporates the organic solvent and water contained in the material layer 2X of the uneven layer, forming the uneven layer 2 (FIG. 4(c)). Moreover, the drying of the material layer 2X of the concavo-convex layer may be performed in two stages, for example, drying or curing may be performed after pre-drying. The uneven layer 2 may be dried at room temperature.

In this step, it is preferable to dry the material layer 2X of the uneven layer after the material layer 2X of the uneven layer disposed between the member 50 and the translucent substrate 1 is decompressed. In this case, the sol-gel material is easily filled in the gaps between the inorganic nanoparticles, and the gaps between the inorganic nanoparticles in the uneven layer 2 obtained can be reduced. Therefore, it is possible to increase the refractive index of the uneven layer 2 to be obtained, and to enhance the adhesion between the uneven layer 2 and the translucent substrate 1 .

The drying temperature is preferably 50°C or higher, more preferably 100°C or higher, preferably 800°C or lower, and more preferably 600°C or lower. When an acrylic resin is added, the drying temperature is preferably 50° C. or higher, more preferably 100° C. or higher, more preferably 200° C. or higher, still more preferably 200° C. or higher, and even more preferably 250° C. or higher. It is more preferably higher than 250°C, still more preferably 300°C or higher, even more preferably 350°C or higher, and particularly preferably 400°C or higher. The drying time is preferably 1 minute or longer, more preferably 10 minutes or longer, preferably 300 minutes or shorter, and more preferably 120 minutes or shorter.

When the material layer 2X of the uneven layer contains resin, it is preferable to burn off the resin by drying the material layer 2X of the uneven layer at 250°C or higher. This makes it possible to increase the proportion of the inorganic nanoparticles in the material constituting the uneven layer 2, and facilitates the formation of the uneven layer 2 with a high refractive index. The drying temperature for burning off is preferably 250° C. or higher, more preferably higher than 250° C., still more preferably 300° C. or higher, still more preferably 350° C. or higher, and particularly preferably 400° C. or higher. If the burn-off temperature is too low, the uneven layer 2 will be colored due to residual carbon components, and the light transmittance will tend to decrease. Although the upper limit of the drying temperature is not particularly limited, it is preferably 600° C. or lower, for example.

When the material layer 2X of the uneven layer is dried at 250°C or higher, the drying atmosphere is preferably an oxidizing atmosphere. This makes it easier to suppress the uneven layer 2 from being colored by the carbon component.

The resin contained in the material layer 2X of the uneven layer after drying (that is, the uneven layer 2) is preferably 10% by mass or less, particularly 5% by mass or less with respect to the weight of the uneven layer 2. This makes it easier to form the uneven layer 2 with a higher refractive index.

A load may also be applied when drying the material layer 2X of the uneven layer. This makes it easier to stabilize the shape of the uneven layer 2 . In addition, it becomes easier to improve the adhesion between the translucent substrate 1 and the concavo-convex layer 2 . The load is, for example, preferably 10 kgf or more, more preferably 20 kgf or more, even more preferably 30 kgf or more, still more preferably 40 kgf or more, and particularly preferably 50 kgf or more. Although the upper limit of the load is not particularly limited, it may be 300 kgf or less, for example.

When curing the material layer 2X of the concavo-convex layer, decompression or pressurization may be performed. In particular, it is preferable to perform a decompression treatment. As a result, air bubbles contained in the material layer 2X of the uneven layer can be removed, making it easier to form the uneven layer 2 with a high refractive index.

Through this process, the material layer 2X of the uneven layer is deformed (shrinked) by volatilizing the solvent or the like or by burning off the resin. If the amount of shrinkage is too large, the uneven layer 2 to be obtained may be greatly deformed from the design structure, and desired optical characteristics may not be obtained. Therefore, as shown in FIG. 5, when the total height of the uneven layer 2 is Ha and the height of the convex portion 21 is H, the shrinkage amount of Ha when the material layer 2X of the uneven layer is dried is 70% or less. is preferably 65% or less, more preferably 60% or less, even more preferably 50% or less, even more preferably 40% or less, 30% The following are particularly preferred. In addition, the H shrinkage amount when the material layer 2X of the uneven layer is dried is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less. % or less, and particularly preferably 10% or less. In particular, by suppressing the amount of contraction of the height H of the convex portion 21 to a small amount, it becomes easier to obtain the optical element 10 having desired optical characteristics. Therefore, the ratio of the amount of H shrinkage to the amount of Ha shrinkage is preferably 0.5 or less, more preferably 0.4 or less.

<Process of removing members>
The member 50 is then removed. As a result, an optical element 10 including the translucent substrate 1 and the concavo-convex layer 2 can be obtained (FIG. 4(d)).

(Second embodiment)
6A to 6D are cross-sectional views for explaining each step of the method for manufacturing an optical element according to the second embodiment of the present invention. 6A to 6D are cross-sectional views for explaining each step of the method of manufacturing the optical element 10 shown in FIG. The method for manufacturing an optical element according to the present embodiment comprises the steps of disposing a material for an uneven layer on a main surface of a translucent substrate to form a material layer for an uneven layer; a step of placing a member having an uneven surface on the surface opposite to the transparent substrate from the surface side; and a step of drying the material layer of the uneven layer placed between the member and the translucent substrate. and removing the member. This embodiment differs from the first embodiment in that the material layer 2X of the uneven layer is arranged on the main surface of the translucent substrate 1. FIG.

In addition, unless otherwise specified, other points such as the preferred configuration of the method for manufacturing an optical element are the same as other points such as the preferred configuration described in the section of the first embodiment.

<Step of Forming Material Layer for Concavo-convex Layer>
First, the material for the uneven layer is arranged on the main surface of the translucent substrate 1 . In this embodiment, the dispenser 60 is used to dispose the material of the uneven layer on the main surface of the translucent substrate 1 . In this manner, the material layer 2X of the concavo-convex layer can be formed on the main surface of the translucent substrate 1 (FIG. 6A). In addition, as described in the column of the first embodiment, instead of the dispenser 60, spin coating or spraying may be used to dispose the material of the uneven layer on the main surface of the translucent substrate 1. .

From the viewpoint of good formation of the uneven layer, the material of the uneven layer is preferably a material containing inorganic nanoparticles or a composite material of a material containing inorganic nanoparticles and a sol-gel material.

It should be noted that, in this step, it is preferable to form the material layer 2X of the uneven layer while degassing under reduced pressure after disposing the material of the uneven layer on the main surface of the translucent substrate 1 . This makes it easier for the bubbles contained in the material of the uneven layer to disappear. As a result, the voids between the inorganic nanoparticles in the resulting uneven layer 2 are reduced, and the inorganic nanoparticles in the uneven layer 2 can be highly packed, that is, the refractive index can be increased, and the strength of the uneven layer 2 can be improved.

<Step of arranging a member having unevenness on the surface>
Next, a member 50 having an uneven surface is placed on the surface of the material layer 2X of the uneven layer opposite to the translucent substrate 1 (FIG. 6B).

In this embodiment, the member 50 is preferably a silicone resin member. Since the member 50 made of silicone resin has relatively high flexibility, it is easy to arrange the member 50 in close contact with the material layer 2X of the concavo-convex layer. That is, entrained bubbles are less likely to occur between the member 50 and the material layer 2X of the concavo-convex layer. If entrapment bubbles are generated, there is a possibility that the adhesion between the translucent substrate 1 and the material layer 2X of the uneven layer is lowered in the step of drying the material layer 2X of the uneven layer, which will be described later. Therefore, according to the method for manufacturing an optical element according to the present embodiment, it is easy to suppress deterioration in adhesion between the translucent substrate 1 and the material layer 2X of the concavo-convex layer. That is, according to the method for manufacturing an optical element according to the present embodiment, it is possible to manufacture the optical element 10 having excellent adhesion between the light-transmitting substrate 1 and the concavo-convex layer 2 .

It is preferable to apply a load to the translucent substrate 1, the material layer 2X of the uneven layer, and the member 50 after arranging the member 50 having unevenness. This makes it easier to stabilize the shape of the uneven layer 2 . In addition, it becomes easier to improve the adhesion between the translucent substrate 1 and the concavo-convex layer 2 . The load is, for example, preferably 10 kgf or more, more preferably 20 kgf or more, even more preferably 30 kgf or more, still more preferably 40 kgf or more, and particularly preferably 50 kgf or more. Although the upper limit of the load is not particularly limited, it may be 300 kgf or less, for example.

As described in the section of the first embodiment, in this step, the material layer 2X for the uneven layer disposed between the member 50 and the translucent substrate 1 is subjected to pressure reduction treatment, and then the material for the uneven layer is removed. It is preferred to dry layer 2X.

<Step of drying the material layer of the concavo-convex layer>
Next, the material layer 2X of the concavo-convex layer arranged between the member 50 and the translucent substrate 1 is dried. The drying evaporates the solvent and water contained in the material layer 2X of the uneven layer, forming the uneven layer 2 (FIG. 6(c)).

The drying temperature is preferably 50°C or higher, more preferably 100°C or higher, preferably 800°C or lower, and more preferably 600°C or lower. Further, when an acrylic resin is added, the drying temperature is preferably 50° C. or higher, more preferably 100° C. or higher, still more preferably 200° C. or higher, still more preferably 200° C. or higher, and still more preferably 250° C. or higher. , more preferably above 250°C, more preferably above 300°C, even more preferably above 350°C, and particularly preferably above 400°C. The drying time is preferably 1 minute or longer, more preferably 10 minutes or longer, preferably 300 minutes or shorter, and more preferably 120 minutes or shorter.

Before drying the material layer 2X for the concavo-convex layer, the laminate composed of the member 50, the material layer 2X for the concavo-convex layer, and the translucent substrate 1 may be turned upside down. That is, after the step of arranging a member having unevenness on the surface (FIG. 6B), the laminate is turned upside down to form a structure similar to that of FIG. The material layer 2X of the uneven layer may be dried in a state in which the material layer 2X of the uneven layer is arranged and the translucent substrate 1 is arranged on the surface of the material layer 2X of the uneven layer opposite to the member 50 side. . This makes it easier to reduce the effect of shrinkage due to drying of the material layer 2X of the uneven layer, and makes it easier to manufacture the optical element 10 in which the tops of the convex portions 21 of the uneven layer 2 are horizontal or convex.

<Process of removing members>
The member 50 is then removed. As a result, an optical element 10 including the translucent substrate 1 and the concavo-convex layer 2 can be obtained (FIG. 6(d)).

It should be noted that, for example, the

optical elements

10A and 10B shown in FIGS. 2 and 3 can be manufactured by using the member 50 having a predetermined uneven surface shape.

(First modification)
A method for manufacturing an optical element according to a first modification of the present invention includes steps of forming a material layer for the uneven layer, drying the material layer for the uneven layer to form the uneven layer, and forming a transparent layer on the uneven layer. arranging an optical substrate. This modification differs from the first embodiment in that it includes a step of placing the translucent substrate 1 on the uneven layer 2 after the uneven layer 2 is formed by drying the uneven layer material layer 2X.

7(a) to (d) are cross-sectional views for explaining each step of the method for manufacturing an optical element according to the first modified example of the present invention. The details of the method for manufacturing the optical element according to the first modification are as follows. First, a member 50 having an uneven surface is prepared. In this modified example, the member 50 is a silicone resin member. A material for the uneven layer is placed on the uneven surface of the member 50 . In this modification, a dispenser (not shown) is used to dispose the material of the uneven layer on the uneven surface of the member 50 . In this manner, the material layer 2X of the uneven layer can be formed on the uneven surface of the member 50 (FIG. 7A). Instead of using a dispenser, spin coating or spraying may be used to dispose the material of the uneven layer on the uneven surface of the member 50 .

Next, the material layer 2X of the uneven layer arranged on the uneven surface of the member 50 is dried (FIG. 7(b)). By drying, the organic solvent and water contained in the material layer 2X of the uneven layer evaporate, and the uneven layer 2 is formed.

Next, the translucent substrate 1 is placed on the surface of the uneven layer 2 opposite to the member 50 side (FIG. 7(c)). At this time, the translucent substrate 1 and the uneven layer 2 can be brought into close contact with each other via an adhesive layer (not shown).

Next, the member 50 is removed. As a result, an optical element 10 including the translucent substrate 1 and the concavo-convex layer 2 can be obtained (FIG. 7(d)).

In general, when the solvent and water contained in the material layer 2X for the uneven layer are evaporated, the resulting uneven layer 2 shrinks compared to the material layer 2X for the uneven layer. Therefore, the adhesion between the translucent substrate 1 and the uneven layer 2 may be lowered due to the contraction. On the other hand, in this modification, since the translucent substrate 1 is arranged on the uneven layer 2 after the uneven layer 2 is formed, the influence of the contraction can be easily reduced.

It should be noted that various preferable configurations described in the section of the first embodiment can be appropriately applied to this modified example.

In a modified example of the present invention, the material layer 2X of the concavo-convex layer may be temporarily placed on a film or a transport substrate before placing the translucent substrate 1. For example, the method of manufacturing an optical element according to the present invention may include a step of transferring the material layer 2X of the concavo-convex layer to a film. As a result, the material layer 2X of the concavo-convex layer can be held and dried on the film, making it easier to reduce manufacturing costs.

(Second modification)
A second modification of the present invention comprises a step of placing a first material on the surface of a member having unevenness on the surface to form a material layer of the first uneven layer; drying the layer to form a first textured layer; disposing a second material on the first textured layer to form a material layer for a second textured layer; drying the material layer of the layer to form a second textured layer; and placing a translucent substrate on the second textured layer. In this modification, the uneven layer 2 is composed of a first uneven layer and a second uneven layer, and includes a step of forming the first uneven layer and a step of forming the second uneven layer, It differs from the first embodiment.

FIGS. 8(a) to (d) and FIGS. 9(e) to (f) are cross-sectional views for explaining each step of the method for manufacturing an optical element according to the second modified example of the present invention. The details of the second modification are as follows. First, a member 50 having an uneven surface is prepared. In this modified example, the member 50 is a silicone resin member. Next, a first material is placed on the uneven surface of the member 50 to form the material layer 201X of the first uneven layer. In this modification, a dispenser (not shown) is used to dispose the material layer 201X of the first uneven layer on the uneven surface of the member 50 . In this modified example, the material layer 201X of the first concavo-convex layer fills a part of the concave portion of the member 50 (FIG. 8A). Instead of using a dispenser, spin coating or spraying may be used to dispose the material of the uneven layer.

Next, the material layer 201X for the first uneven layer is dried to form the first uneven layer 201. The drying evaporates the organic solvent and water contained in the material layer 201X of the first uneven layer, forming the first uneven layer 201 (FIG. 8B).

Next, a second material is placed on the first uneven layer to form a material layer 202X for the second uneven layer. The material layer 202X for the second uneven layer can be placed using, for example, a dispenser (not shown), similarly to the material layer 201X for the first uneven layer. In this modification, the material layer 202X of the second uneven layer fills the concave portions of the member 50 that are not filled with the first uneven layer 201 (FIG. 8C). Instead of using a dispenser, spin coating or spraying may be used to dispose the material of the uneven layer.

Next, the material layer 202X for the second uneven layer is dried to form the second uneven layer 202. The drying evaporates the organic solvent and water contained in the material layer 202X for the second uneven layer, forming the second uneven layer 202 (FIG. 8D).

Next, the translucent substrate 1 is placed on the surface of the second uneven layer 202 opposite to the member 50 side. At this time, the translucent substrate 1 and the second uneven layer 202 can be brought into close contact via an adhesive layer (not shown) (FIG. 9(e)).

Next, the member 50 is removed. As a result, an optical element 10C including the translucent substrate 1, the first uneven layer 201 and the second uneven layer 202 can be obtained (FIG. 9F).

According to this modified example, as in the first modified example, it becomes easier to suppress a decrease in the adhesive strength between the uneven layer and the translucent substrate 1 . In addition, by forming the uneven layer separately into the first uneven layer 201 and the second uneven layer 202, the radius of curvature of the end portion is likely to be small, and the uneven layer with excellent optical properties can be easily obtained. The translucent substrate 1 and the second uneven layer 202, and the first uneven layer 201 and the second uneven layer 202 may be adhered to each other via an adhesive layer (not shown).

Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is by no means limited to the following examples, and can be modified as appropriate without changing the gist of the invention.

The following translucent substrate was prepared.

<Translucent substrate (a)>
Translucent substrate (a) has a glass composition of 5.0% by mass SiO ₂ , 10.0% B ₂ O ₃ , 15.0% TiO _{2 ,} 10.0% Nb ₂ O ₅ and ZrO. ₂ 5.0%, La ₂ O ₃ 49.0%, Gd ₂ O ₃ 5.0%, Y ₂ O ₃ 1.0%. It had a refractive index (n) of 1.80 at a wavelength of 530 nm, an Abbe number (νd) of 40.0, an average thermal expansion coefficient of 80×10 ⁻⁷ /° C. at 30° C. to 100° C., and a thickness of 1 mm.

<Translucent substrate (b)>
The translucent substrate (b) has a glass composition _of 70.0% by mass _Bi2O3 , 8.0% _B2O3 _, _11.0 % TeO2, and _5.0 % _P2O5 . , Nb ₂ O ₅ 5.0%, ZnO 1.0%. It had a refractive index (n) of 2.20 at a wavelength of 530 nm, an Abbe number (νd) of 18.0, an average thermal expansion coefficient of 120×10 ⁻⁷ /° C. at 30° C. to 100° C., and a thickness of 1 mm.

<Translucent substrate (c)>
Translucent substrate (c) has a glass composition of 5.0% by mass of SiO ₂ , 5.0% of B ₂ O ₃ , 15.0% of TiO _{2 ,} 10.0% of Nb ₂ O ₅ and ZrO. ₂ 5.0%, _La2O3 _50.0 % _, _Gd2O3 _5.0 %, _Y2O3 5.0%. The refractive index (n) at a wavelength of 530 nm was 2.00, the Abbe number (νd) was 29.0, the average thermal expansion coefficient at 30°C to 100°C was 80 × 10 ^-7 /°C, and the thickness was 1 mm. .

<Translucent substrate (d)>
Translucent substrate (d) _has a glass composition of 65.9% by mass _SiO2 , 11.0% _B2O3 , _1.0 % _Al2O3 , 5.0% ZnO, and MgO3. .0%, BaO 2.0%, CaO 3.0%, _Na2O 5.0%, _K2O 4.0%, _Sb2O3 _0.1 %. The refractive index (n) at a wavelength of 530 nm was 1.55, the Abbe number (νd) was 60.0, the average thermal expansion coefficient at 30°C to 100°C was 40 × 10 ^-7 /°C, and the thickness was 1 mm. .

The following composition was prepared as a material for forming the uneven layer.

<Composition A>
A composition A was prepared by mixing 30% by mass of ZrO ₂ particles (average particle size: 5 nm) as inorganic nanoparticles and 70% by mass of butanol as a solvent.

<Compositions B to I>
Compositions B to I were prepared in the same manner as composition A, except that the type of inorganic nanoparticles, the type of solvent, or the mixing ratio was changed as shown in Tables 1 and 2.

<Composition AA>
A material based on MTES (methyltriethoxysilane) was used as the _SiO2 sol-gel material.

<Composition AB>
A titanate metal alkoxide solution was used as the _TiO2 sol-gel material.

<Composition X>
A composition X was prepared by mixing 30% by mass of ZrO ₂ particles (average particle size: 10 μm) as particles not corresponding to inorganic nanoparticles and 70% by mass of butanol as a solvent.

<Composition Y>
As composition Y, an acrylic resin was used.

The details of the obtained compositions A to I, AA, AB, X and Y are shown in Tables 1 to 4 below.

(Example 1)
In Example 1, an optical element having the shape shown in FIG. 1 was produced according to the method shown in FIG. Specifically, an optical element was produced as follows.

Production of a member having unevenness on the surface (silicone resin member):
A mold (Si substrate (silicon substrate)) having linear grooves with a depth of 500 nm, a width of 500 nm, and a groove interval of 500 nm in an area of 10 mm long×10 mm wide was prepared. Also, a thermosetting silicone resin component and a curing agent were prepared. After setting the formwork in the mold, the thermosetting silicone resin component was poured into the mold and cured by heating at 150° C. for 1 hour. The mold and mold were removed to obtain a silicone resin member.

Step of forming the material layer of the uneven layer:
The above composition A was used as a material for the uneven layer. A spacer with a thickness of 1 μm was arranged on the uneven surface of the silicone resin member. Next, using a dispenser, the material for the uneven layer was placed on the uneven surface of the silicone resin member to form a material layer for the uneven layer.

The process of arranging the translucent substrate:
The translucent substrate (a) was used as a translucent substrate. A translucent substrate was placed on the surface of the material layer of the uneven layer opposite to the side of the silicone resin member.

Drying the material layer of the uneven layer:
By heating from the side of the silicone resin member and the side of the translucent substrate, the material layer of the concavo-convex layer disposed between the silicone resin member and the translucent substrate was dried. Specifically, it was preheated at 30° C. for 12 hours and then dried at 120° C. for 1 hour.

Step of removing the silicone resin member:
By removing the silicone resin member, an optical element having a translucent substrate and an uneven layer was obtained. The uneven layer in the obtained optical element has convex portions of the uneven layer such that the convex portions of the uneven layer are linear convex portions parallel to each other, and the height H of the convex portions of the uneven layer is 500 nm. The uneven layer was formed so that the width W was 500 nm, the period P in the periodic structure of the uneven layer was 1000 nm, and the minimum thickness of the uneven layer (the thickness of the concave portion) was 500 nm.

(Examples 2-11, Examples 15-17 and Comparative Examples 1-3)
Shown in FIG. 1 in the same manner as in Example 1 except that the type of translucent substrate, the type of material for the uneven layer, and the drying temperature of the material for the uneven layer were changed as shown in Tables 5 to 7. An optical element having a shape was produced. For example, in Example 2, it means that a mixed material of 80% by mass of composition A and 20% by mass of composition B was used as the material of the uneven layer.

(Examples 12 and 13)
The type of material for the uneven layer was changed as shown in Table 6. In addition, in the "step of drying the material layer of the uneven layer", the laminate of the member, the material layer of the uneven layer, and the translucent substrate is placed in an acrylic container connected to a vacuum pump, and the pressure is reduced to 0.1 MPa. After treatment, the material layer of the relief layer was dried. Also, the drying temperature of the material of the concavo-convex layer was changed as shown in Table 6. An optical element having the shape shown in FIG. 1 was produced in the same manner as in Example 1 except for these.

(Example 14)
Instead of using a dispenser, a spray was used to form the material layer of the relief layer. First, the composition shown in Table 7 was introduced into a sprayer to form a material layer of uneven layer having a thickness of 500 nm on a translucent substrate. Next, a silicone resin member was placed on the material layer of the formed concavo-convex layer and dried at room temperature for 12 hours. After that, the silicone resin member was removed and dried at the temperature shown in Table 7. An optical element having the shape shown in FIG. 1 was produced in the same manner as in Example 1 except for these.

(Examples 18 and 19)
Instead of using a dispenser, the material layer of the uneven layer was formed by spin coating. First, the composition shown in Table 8 was spin-coated at a rotation speed of 1000 rpm for 10 seconds to form a 500 nm-thick uneven layer material layer on a translucent substrate. Next, a silicone resin member was placed on the material layer of the formed concavo-convex layer and dried at room temperature for 12 hours. After that, the silicone resin member was removed and dried at the temperature shown in Table 8. An optical element having the shape shown in FIG. 1 was produced in the same manner as in Example 1 except for these.

(Examples 20-24)
Instead of using a dispenser, the material layer of the uneven layer was formed by spin coating. First, 0.001% by mass of a polymerization initiator was added to the composition shown in Table 8. Next, spin coating was performed at a rotation speed of 1000 rpm for 10 seconds to form a 500 nm-thick uneven layer material layer on the translucent substrate. Next, a silicone resin member was placed on the formed material layer for the uneven layer, and UV light was applied to cure the material layer for the uneven layer. At this time, in Examples 22 and 23, after placing the silicone resin member, it was cured while applying the load shown in Table 8. After that, the silicone resin member was removed and dried at the temperature shown in Table 8 for 1 hour. An optical element having the shape shown in FIG. 1 was produced in the same manner as in Example 1 except for these.

[evaluation]
(1) Refractive index of uneven layer Using the same material as the uneven layer, a sample was separately prepared by applying it to a thickness of 1 μm with a spin coater. was measured. Also, the absolute value of the difference between the refractive index of the obtained sample and the refractive index of the translucent substrate was obtained.

(2) Abbe number of the uneven layer Using the same material as the uneven layer, a sample was separately prepared by applying it to a thickness of 1 μm with a spin coater, and the Abbe number was measured using a spectroscopic ellipsometer ("UVISEL2" manufactured by Horiba, Ltd.). asked for Also, the value of the formula: y+50x was calculated from the Abbe's number (y) of the obtained uneven layer and the refractive index (x) of the uneven layer obtained in the above "(1) Refractive index of uneven layer".

(3) Average Thermal Expansion Coefficient of Concavo-convex Layer A cylindrical sample was separately prepared using the same material as the concavo-convex layer, and the average thermal expansion coefficient at 30° C. to 100° C. was measured by the TMA method.

(4) Raman spectrum measurement of the uneven layer Using the same material as the uneven layer, a sample was separately prepared by applying it to a thickness of 1 μm with a spin coater, and the Raman spectrum was measured with a laser Raman microscope (measurement conditions: the objective lens was TU Plan Fluor 100X, spectrometer center wavenumber 2700.00 cm ⁻¹ , diffraction grating 300 gr/mm, pinhole size 50 μm, exposure time 10 seconds, averaging 5). From the obtained spectrum, the ratio of the maximum peak intensity A within the range of 2900 cm ^-1 to 3000 cm ^-1 to the maximum peak intensity B within the range of 100 cm ^-1 to 1000 cm ^-1 (maximum peak intensity A / maximum peak intensity B) was calculated.

(5) Light transmittance of optical element (wavelength 500 nm)
Using a transmittance meter ("V-670" manufactured by Shimadzu Corporation), the optical element obtained was measured for light transmittance at a wavelength of 300 nm to 800 nm, and the light transmittance at a wavelength of 500 nm was obtained. A sample with a light transmittance of 55% or more was rated as "◯", and a sample with a light transmittance of less than 55% was rated as "x".

(6) Shape Maintainability of Concavo-convex Layer In the obtained optical element, the light-transmitting substrate was scribed so as to be perpendicular to the linear convex portions, and then broken. Using an electron microscope, the cross section of the concavo-convex layer was observed at a magnification of 10000 times. If the height of the protrusion exceeds 450 nm and the width of the upper surface of the protrusion exceeds 450 nm, the shape retention of the uneven layer is "O", the height of the protrusion is 450 nm or less, or the upper surface of the protrusion The shape retention property of the concavo-convex layer was determined to be "x" when the width of the concavo-convex layer was 450 nm or less.

(7) Peel Test A 19 mm test adhesive tape defined by JIS Z 1522 was attached to the surface of the uneven layer of the obtained optical element, and then the tip of the test adhesive tape was peeled off from the surface of the uneven layer. After that, the uneven layer was observed using a laser microscope. A case where the uneven layer was not peeled was evaluated as "O", and a case where the uneven layer was peeled was evaluated as "X".

(8) Heat resistance test (300 ° C. and 1 hour)
The obtained optical element was heat-treated at 300° C. for 1 hour. Then, using a digital microscope, the cross section of the optical element was observed to evaluate the heat resistance. Specifically, when the concavo-convex layer did not separate from the light-transmitting substrate, it was evaluated as "O", and when the concavo-convex layer peeled off from the light-transmitting substrate, it was evaluated as "x".

Details and results are shown in Tables 5 to 8 below.

(9) Drying Conditions and Shrinkage of Concavo-convex Layer After coating on the translucent substrate shown in Table 9 with a spin coater to a thickness of 500 nm, a mold for transferring the concavo-convex pattern was placed and UV cured. Examples 25-1 and 26-1 were obtained. Next, these samples were dried at 350° C. for 5 hours to obtain Examples 25-2 and 26-2. The total height Ha of the uneven layer and the height H of the protrusions were measured for the samples before and after drying. Also, the shrinkage (%) of Ha and H before and after drying, and the shrinkage of H relative to the shrinkage of Ha were determined.

As shown in Table 9, Ha and H shrunk due to heat treatment. Moreover, in Example 25, the amounts of shrinkage of Ha and H were smaller than those of Example 26, and the amount of shrinkage of H relative to the amount of shrinkage of Ha was smaller. In other words, the contraction amount (deformation amount) of the protrusions was smaller than the contraction amount of the entire uneven layer.

(10) Drying conditions and light transmittance of optical element (wavelength 450 nm)
After fabricating an optical element using the same material as in Example 20, it was dried under the conditions shown in Table 10. Specifically, after UV curing, drying was performed at the temperature and atmosphere shown in Table 10 for 3 hours. At this time, Examples 27-2 and 27-4 were subjected to pressure reduction treatment to 0.1 MPa. After drying, the light transmittance at a wavelength of 300 nm to 800 nm was measured using a transmittance meter ("V-670" manufactured by Shimadzu Corporation) to determine the light transmittance at a wavelength of 450 nm.

As shown in Table 10, the higher the drying temperature, the higher the light transmittance of the optical element.

The optical element of the present invention can be suitably used as an optical diffraction element or a light guide plate provided with a diffraction structure.

Reference Signs List 1

Translucent substrate

2, 2A, 2B, 201, 202

Uneven layer

2X, 201X, 202X Material layer of

uneven layer

10, 10A, 10B,

10C Optical element

21,

21A Convex

22, 22B Concave 50... Member 60... Dispenser D... Depth H... Height P... Period W... Width

Claims

a translucent substrate;
an uneven layer disposed on the main surface of the translucent substrate and having unevenness on the surface;
The uneven layer contains inorganic nanoparticles,
An optical element, wherein the absolute value of the difference between the refractive index of the translucent substrate and the refractive index of the uneven layer is 0.20 or less.
The optical element according to claim 1, wherein the apexes of the projections of the uneven layer are horizontal or convex.
3. The optical element according to claim 1 or 2, wherein the radius of curvature at the end of the convex portion of the uneven layer is smaller than the radius of curvature at the end of the concave portion of the uneven layer.
In the Raman spectrum, the uneven layer has a ratio of maximum peak intensity A within the range of 2900 cm -1 to 3000 cm -1 to maximum peak intensity B within the range of 100 cm -1 to 1000 cm -1 (maximum peak intensity A /maximum peak intensity B) is 4.0 or less, the optical element according to claim 1 or 2.
The optical element according to claim 1 or 2, wherein the uneven layer has a refractive index of 1.60 or more.
The optical element according to claim 1 or 2, wherein the uneven layer has an Abbe number of 5 or more and 35 or less.
3. The optical system according to claim 1, wherein the value represented by the formula: y+50x is 100 or more and 125 or less, where x is the refractive index of the uneven layer and y is the Abbe number of the uneven layer. element.
2. The inorganic nanoparticles are at least one inorganic nanoparticle selected from the group consisting of ZrO2 , BaTiO3 , TiO2 , Al2O3 , Nb2O5 , SiO2 and KTaO3 . 3. or the optical element according to 2.
The uneven layer contains, as the inorganic nanoparticles, inorganic nanoparticles A and inorganic nanoparticles B having an average particle diameter smaller than that of the inorganic nanoparticles A,
When the average particle diameter of the inorganic nanoparticles A is D A nm and the average particle diameter of the inorganic nanoparticles B is D B nm, the average particle diameter of the inorganic nanoparticles B is The optical element according to claim 1 or 2, wherein the ratio (D A /D B ) to the average particle size is 1.5 or more and 20.0 or less.
The optical element according to claim 1 or 2, wherein the content of the inorganic nanoparticles is 10% by mass or more in 100% by mass of the uneven layer.
The optical element according to claim 1 or 2, which has a light transmittance of 55% or more at a wavelength of 500 nm.
3. The method according to claim 1, wherein the ratio h2/h1 of the height h1 at the ends of the projections of the uneven layer and the height h2 at the center of the projections is 0.9 to 1.3. optical element.
The optical element according to claim 1 or 2, wherein the translucent substrate is a glass substrate.
The optical element according to claim 1 or 2, which is used as an optical diffraction element.
The optical element according to claim 1 or 2, wherein the translucent substrate and the uneven layer are in direct contact.
The optical element according to claim 1 or 2, wherein the translucent substrate and the uneven layer are in close contact with each other via an adhesive layer.
The optical element according to claim 1 or 2, having a thin film layer on the uneven layer.
The thin film layer is selected from the group consisting of Y2O3 , Al2O3 , SiO2 , MgO , TiO2 , CeO2 , Bi2O3 , HfO2 , Al, Ag, Au, Pt and carbon. 18. Optical element according to claim 17, consisting of at least one material.
A method for manufacturing an optical element,
a step of disposing a material for the uneven layer on the surface of a member having unevenness on the surface to form a material layer for the uneven layer;
disposing a translucent substrate on the surface of the material layer of the uneven layer opposite to the member;
a step of drying a material layer of the concavo-convex layer disposed between the member and the translucent substrate;
and removing the member.
20. The method according to claim 19, wherein in the step of forming the material layer of the uneven layer, the material layer of the uneven layer is formed while degassing under reduced pressure after disposing the material of the uneven layer on the surface of the member. A method for manufacturing the optical element described.
20. The method for manufacturing an optical element according to claim 19, wherein in the step of arranging the translucent substrate, the translucent substrate is arranged on a spacer placed on the member.
A method for manufacturing an optical element,
disposing a material for the uneven layer on the main surface of the translucent substrate to form a material layer for the uneven layer;
a step of disposing a member having an uneven surface on the surface of the material layer of the uneven layer opposite to the light-transmitting substrate side from the surface side;
a step of drying a material layer of the concavo-convex layer disposed between the member and the translucent substrate;
and removing the member.
A method for manufacturing an optical element,
A step of forming a material layer of an uneven layer on the surface of a member having unevenness on the surface;
a step of drying the material layer of the uneven layer to form an uneven layer;
and disposing a translucent substrate on the concavo-convex layer.
A method for manufacturing an optical element,
disposing a first material on the surface of a member having an uneven surface to form a material layer of a first uneven layer;
drying the material layer of the first uneven layer to form a first uneven layer;
disposing a second material on the first uneven layer to form a material layer of the second uneven layer;
drying the material layer of the second uneven layer to form a second uneven layer;
and placing a translucent substrate on the second uneven layer.
The method for manufacturing an optical element according to any one of claims 19 to 24, wherein the material of the uneven layer is a material containing inorganic nanoparticles or a composite material of a material containing inorganic nanoparticles and a sol-gel material.
The method for manufacturing an optical element according to claim 25, wherein the material of the uneven layer contains resin.
The method for manufacturing an optical element according to claim 26, wherein the resin is burned off by drying the material layer of the uneven layer at 250°C or higher.
The ratio of the amount of shrinkage of H to the amount of shrinkage of Ha when the material layer of the uneven layer is dried is 0.5 or less, where Ha is the total height of the uneven layer and H is the height of the convex portion. 25. A method for manufacturing an optical element according to any one of 19 to 24.
The method for manufacturing an optical element according to any one of claims 19 to 24, further comprising the step of transferring the material layer of the uneven layer to a film.