JP5863265B2 - Optical element and multilayer diffractive optical element - Google Patents

Description

  The present invention relates to an optical element and multilayer diffractive optical element used for a camera, a video, and the like.

  Conventionally, in a refractive optical system using light refraction, chromatic aberration is reduced by combining lenses made of glass materials having different dispersion characteristics. For example, in an objective lens such as a telescope, a glass material with small dispersion is used as a positive lens and a glass material with high dispersion is used as a negative lens, and these are used in combination to correct chromatic aberration appearing on the axis. However, when the configuration and number of lenses are limited, or when the glass material used is limited, it may be difficult to sufficiently correct chromatic aberration.

  Non-Patent Document 1 discloses that chromatic aberration is suppressed with a small number of lenses by using a combination of a refractive optical element having a refractive surface and a diffractive optical element having a diffraction grating.

  This utilizes the physical phenomenon that the direction in which chromatic aberration occurs with respect to a light beam having a certain reference wavelength is reversed between the refracting surface and the diffractive surface as an optical element. Further, by changing the period of the diffraction grating formed continuously in the diffractive optical element, it is possible to exhibit characteristics equivalent to those of the aspherical lens.

  However, one light beam incident on the diffractive optical element is divided into a plurality of lights of each order by the diffraction action. At this time, the diffracted light other than the design order forms an image at a place different from the light of the design order and causes flare.

  In Patent Document 1, by using a relatively low-refractive-index and high-dispersion optical material and a high-refractive-index and low-dispersion optical material, the luminous flux in the operating wavelength region is concentrated to a specific order (hereinafter referred to as a design order). The intensity of diffracted light of other diffraction orders is kept low, and flare is prevented.

In Patent Document 1, in order to obtain a configuration having high diffraction efficiency in a wide wavelength range, a relatively low refractive index low refractive index high dispersion optical material (n _d is 1.48 <n d _<1 .57) and refractive index dispersion is high (Abbe's number "[nu _d" is 14 <ν _d <28) and low second-order dispersion characteristic ( "theta _gF" is 0.34 <θ _gF <0.47) properties material and a relatively high refractive index and low dispersion of refractive index in the optical material is high _{(n d} is 1.54 _<n d <1.63) and a higher refractive index dispersion (Abbe number "[nu _d" is 44 < The diffraction efficiency in the entire visible region is improved by imparting a shape to the material having ν _d <57) by ultraviolet curing or the like.

  The optical material having a low refractive index and high dispersion in Patent Document 1 is obtained by mixing and dispersing a transparent conductive metal oxide having a high refractive index dispersion and a low secondary dispersion characteristic as fine particles in a low refractive index binder resin. It is obtained by curing the composite material with ultraviolet rays. Moreover, as the transparent conductive metal oxide, a transparent conductive metal oxide such as ITO is used.

JP 2008-203821 A

A. D. Katman and S.K. K. Pitalo, “Binary Optics in Lens Design”, International Lens Design Conference ”, 1990, SPIE Vol. 1354, p297 to 309

  A multilayer diffractive optical element partially using a transparent conductive fine particle dispersion material such as ITO exhibits a high diffraction efficiency state in the entire visible range. However, the optical properties of the ITO dispersion material vary under the usage environment. This eliminates the state of high diffraction efficiency over the entire visible range of the multilayer diffractive optical element.

  The present invention has been made in view of such a background art, and provides an optical element and a multilayer diffractive optical element that can maintain a high diffraction efficiency state in the entire visible region without changing with time. .

An optical element that solves the above-described problem is an optical element having a resin layer between two transparent substrates, and indium tin oxide (ITO) fine particles of 1% by volume or more and 29 volumes on one transparent substrate. % And a second layer that transmits oxygen, and a height of 50 μm or more and 5 mm between the second layer and the other transparent substrate. A closed space for supplying oxygen is provided, and the oxygen concentration in the closed space for supplying oxygen is 10% by volume or more and 100% by volume or less .

An optical element that solves the above-described problem is an optical element having a resin layer between two transparent substrates, and on one transparent substrate, indium tin oxide (ITO) fine particles are 1 vol% or more. having a first layer formed of a resin containing 29% by volume or less, between the first layer and the other transparent substrate, the height is a closed space for supplying less oxygen 5mm above 50μm The concentration of oxygen contained in the closed space for supplying oxygen is 10% by volume or more and 100% by volume or less .

A multilayer diffractive optical element that solves the above-mentioned problems is a multilayer diffractive optical element in which a resin layer is provided between two transparent substrates, and fine particles of indium tin oxide (ITO) are placed on one transparent substrate. A first layer having a diffraction grating shape and a second layer having a diffraction grating shape on the surface of at least one side, which is formed of a resin containing 1% by volume or more and 29% by volume or less, and which transmits oxygen. The first layer and the second layer are laminated so that the diffraction grating shapes are opposed to each other, and oxygen having a height of 50 μm or more and 5 mm or less is supplied between the second layer and the other transparent substrate. A closed space is provided, and the concentration of oxygen contained in the closed space for supplying oxygen is 10% by volume to 100% by volume .

A multilayer diffractive optical element that solves the above-mentioned problems is a multilayer diffractive optical element in which a resin layer is provided between two transparent substrates, and has one diffraction grating shape and is made of a transparent material made of a high refractive and low dispersion material. A first layer which is formed of a resin containing indium tin oxide (ITO) fine particles of 1 volume% or more and 29 volume% or less on a substrate and has a diffraction grating shape on at least one surface thereof is the one transparent A closed space for supplying oxygen having a height of 50 μm or more and 5 mm or less is provided between the first layer and the other transparent substrate so that the diffraction grating shapes of the substrate and the first layer are opposed to each other. Provided ,
The concentration of oxygen contained in the closed space for supplying oxygen is 10 volume% or more and 100 volume% or less .

  ADVANTAGE OF THE INVENTION According to this invention, the optical element and multilayer diffractive optical element which can maintain the high diffraction efficiency state of the whole visible region, without changing with time can be provided.

1 is a schematic diagram showing an embodiment of a multilayer diffractive optical element of the present invention. It is a schematic diagram which shows the other embodiment of the multilayer diffractive optical element of this invention. 1 is a schematic diagram showing an embodiment of a multilayer diffractive optical element of the present invention. It is a schematic diagram which shows the other embodiment of the multilayer diffractive optical element of this invention. It is a schematic diagram which shows the preparation methods of the sample for refractive index measurement. It is a schematic diagram which shows the preparation methods of the multilayer diffractive optical element for evaluation of diffraction efficiency. It is a schematic diagram which shows the preparation methods of the multilayer diffractive optical element for evaluation of diffraction efficiency. 3 is a schematic diagram illustrating a sample structure for refractive index measurement of Example 1. FIG. 2 is a schematic diagram illustrating a structure of a multilayer diffractive optical element for evaluating diffraction efficiency of Example 1. FIG. 5 is a schematic diagram showing a sample structure for refractive index measurement of Comparative Example 1. FIG. 6 is a schematic diagram showing the structure of a multilayer diffractive optical element for evaluation of diffraction efficiency in Comparative Example 1. FIG.

  In the production of the optical element, the resin composition containing the ITO fine particles and the monomer is irradiated with ultraviolet rays and visible light having a short wavelength and cured to produce an optical material made of a resin. Under normal use, radicals are generated by the photochemical reaction of the resin with ultraviolet light and visible light having a short wavelength. The generated radicals are trapped in the ITO fine particles and act as ITO carriers. At this time, ITO is reduced by radicals, and optical characteristics such as refractive index and light absorption are changed and influenced. Specifically, the refractive index / absorption on the long wavelength side (λ = 500 to 700 nm) in the visible region changes greatly. As a result, the high diffraction efficiency state of the initial optical element deviates from the diffraction conditions due to the refractive index variation of the ITO dispersion material, and the diffraction efficiency deteriorates.

  By taking oxygen in the atmosphere and bringing it into contact with the ITO dispersion material, the present inventors extinguish radicals trapped in the ITO fine particles by oxygen, and oxidize the reduced ITO to return it to its original state. It has been found that optical properties such as refractive index and light absorption are improved.

  An optical element according to the present invention includes a first layer formed by energy-curing a resin composition containing fine particles and a monomer made of a transparent conductive material on a transparent substrate, and a second layer that transmits oxygen. And a space for supplying oxygen is provided on the second layer.

  The optical element according to the present invention includes a first layer formed by energy curing a resin composition containing fine particles and a monomer made of a transparent conductive material on a transparent substrate, A space for supplying oxygen is provided on this layer.

  The multilayer diffractive optical element according to the present invention has a diffraction grating shape made of a resin formed by energy curing a resin composition containing fine particles and a monomer made of a transparent conductive material on a transparent substrate. A layer and a second layer that transmits oxygen and has a diffraction grating shape on at least one surface thereof, are laminated so that the diffraction grating shapes of the first layer and the second layer face each other; and A space for supplying oxygen is provided on the second layer.

  The multilayer diffractive optical element according to the present invention has a diffraction grating shape, and energy cures a resin composition containing fine particles and monomers made of a transparent conductive material on a transparent substrate made of a high refractive and low dispersion material. A first layer having a diffraction grating shape on at least one surface is laminated such that the transparent substrate and the diffraction grating shape of the first layer face each other, and the first layer A space for supplying oxygen is provided on one layer.

  As described above, the optical element of the present invention has a space for supplying oxygen on the second layer, so that the material in which the transparent conductive material is dispersed can be converted into a long wavelength refractive index / transmittance by ultraviolet rays or light. Can be suppressed.

  It is preferable that the first layer is made of a low refractive index and high dispersion material, and the second layer is made of a high refractive index and low dispersion material.

  Preferably, the first layer and the second layer are made of an energy curable resin, and the resin is a radical curable resin made of at least one selected from an acrylic resin, a vinyl resin, and an epoxy resin. .

  Hereinafter, the optical element according to the present invention will be described in detail.

  An optical element according to the present invention includes a first layer formed by energy-curing a resin composition containing fine particles and a monomer made of a transparent conductive material on a transparent substrate, and a second layer that transmits oxygen. And a space for supplying oxygen is provided on the second layer.

  As the transparent substrate, for example, a glass substrate and a glass lens are used.

(About the first layer)
In the present invention, the resin composition for forming the first layer includes fine particles made of a transparent conductive material, a monomer, a dispersion solvent, a surface treatment agent, a dispersant (surfactant), a monomer, and the like. It consists of a composition to contain.

  Preferred examples of the fine transparent conductive material contained in the resin constituting the first layer of the present invention include zinc oxide, indium oxide, tin oxide, antimony oxide, indium tin oxide (ITO), and antimony. Examples include doped tin oxide (ATO), zinc-doped indium oxide (IZO), aluminum-doped zinc oxide (AZO), and fluorine-doped tin oxide (FTO). In particular, indium tin oxide (ITO) is preferably used. Indium tin oxide (ITO) is a material that has the lowest secondary dispersion characteristic (θgF) among the existing materials and maintains the most transparency. However, this does not limit the use of a material having a small secondary dispersion characteristic (θgF) and more transparent than indium tin oxide (ITO) in the future.

  In addition, it is preferable to use various surface treatment agents and dispersants on the surface of the fine particles in accordance with a solvent in which the monomer serving as the base resin and the fine particles are previously dispersed.

  The average particle size of the fine particles is preferably a particle size that does not adversely affect light transmittance, optical scattering, etc., and is in the range of 1 nm to 100 nm, preferably 2 nm to 30 nm, particularly 2 nm to 20 nm. It is preferable that However, for example, even when the average particle size is 20 nm or less, the particles having a wide particle size distribution and a particle size larger than 30 nm, including the case where the fine particles are aggregated, have a volume fraction of 5% or more of the total fine particles. Greatly affects the optical scattering. In that case, it is preferable to remove unnecessary large fine particles by performing filtration with a filter having pores relatively smaller than the particle size to be removed. The timing of removing the fine particles may or may not depend on whether the fine particles are dispersed in the solvent before the base resin is mixed (fine particle dispersion), the base resin is dissolved in the fine particle dispersion, or the viscosity. The solvent is preferably removed in a solvent-free system of the base resin and fine particles.

  It is desirable to subject the fine particles to surface treatment as necessary. Each surface treatment may be performed at the stage of synthesis and production of fine particles, or may be performed separately after obtaining fine particles alone.

  The volume content of the fine particles made of the transparent conductive material in the resin composition for forming the first layer is 1 vol. % Or more 29 vol. % Or less, preferably 5 vol. % Or more and 23 vol. % Or less is desirable.

  Examples of the dispersion solvent used in the present invention include toluene, benzene, xylene and the like for dissolving the binder component or for dispersing fine particles in the solvent, and for dissolving the surface treatment agent and the dispersant as necessary. Aromatic hydrocarbons, alcohols such as ethanol and isopropanol, alicyclic hydrocarbons such as cyclohexane, acetates such as ethyl acetate and butyl acetate, ketones such as acetone and methyl ethyl ketone, amides such as DMF, DMAc and NMP , Aliphatic hydrocarbons such as hexane and octane, ethyls such as diethyl ether and butyl carbitol, halogenated hydrocarbons such as dichloromethane and carbon tetrachloride, and the like, but are not limited thereto. The dispersion solvent can be selected in accordance with the affinity of the fine particles to be used, the surface treatment agent, and the affinity of the dispersing agent, and only one kind of solvent can be used. It can also be used in combination of more than one type. The dispersion solvent is removed in the process of preparing the resin composition.

  The content of the dispersion solvent contained in the resin composition for forming the first layer is 0.2% by weight or less, preferably 0.05% by weight, based on the resin composition forming the first layer. The following is desirable.

  In the present invention, the following surface treatment agent and dispersant (surfactant) for uniformly dispersing fine particles so as not to aggregate are desirable. In general, when fine particles are dispersed in a solvent, resin, etc. using a surface treatment agent and a dispersant, the dispersion state is completely different depending on the type, amount, molecular weight, polarity, affinity, etc. of the surface treatment agent and dispersant to be added. It is known. As the surface treatment agent and dispersant used in the present invention, pigment derivatives, resin types and activator types can be suitably used. Here, as the surface treating agent and the dispersing agent, cationic, weak cationic, nonionic or amphoteric surfactants are effective. Especially polyester-based, ε-caprolactone-based, polycarboxylate, polyphosphate, hydrostearate, amide sulfonate, polyacrylate, olefin maleate copolymer, acrylic-maleate copolymer, Alkylamine acetates, alkyl fatty acid salts, fatty acid polyethylene glycol esters, silicones, and fluorines can be used. In the present invention, at least one base selected from ammonia and organic amines should be used. Is preferred. Specifically, in the Dispersic series (manufactured by Big Chemie Japan), in the Dispersic 161, 162, 163, 164, in the Solsperse series (manufactured by Zenega), Solsperse 3000, 9000, 17000, 20000, 24000, 41090 Alternatively, in the TAMN series (manufactured by Nikko Chemical Co., Ltd.), there are PO or EO modified products of alkylamines such as TAMN-15. Moreover, a dispersing agent can also be used only by 1 type, and can also be used in combination of 2 or more types.

  The content of the surface treatment agent and the dispersant contained in the resin composition for forming the first layer is roughly divided into the surface treatment agent, the kind of the dispersant, the kind of fine particles, and the surface area (fine particle diameter) of the fine particles. Depending on the type of dispersion solvent, such as the type of dispersion resin in which the fine particles are mixed, it is 0.1% by weight or more and 25.0% by weight or less, preferably 4.0% by weight or more, based on the weight of the fine particles. A range of 20.0% by weight or less is desirable. If the amount of the dispersant added is more than 25.0% by weight, white turbidity is caused and optical scattering occurs, and the characteristics of the composition obtained by containing fine particles (refractive index, Abbe number, secondary order) The dispersion characteristics, elastic modulus, etc.) are reduced more than necessary.

  In the present invention, a monomer that is a binder component as a base resin is selected so that the transparent conductive metal oxide fine particles are well-dispersed in a solvent, a surface treatment agent, and a dispersing agent. desirable.

  The monomer is not particularly limited as long as it has one or more double bonds or triple bonds in the molecule. Specific examples of monomers or oligomers of unsaturated group-containing compounds include: 1,4-divinylcyclohexane, 1,4-cyclohexanedimethanol divinyl ether, 4,4-dimethyl-hept-1-ene-6-in, divinylbenzene, 1,6-divinylnaphthalene, N-vinylpyrrolidone, N -Monofunctional acrylates and methacrylates such as vinyl caprolactam, ethoxylated bisphenol A divinyl ether, propoxylated bisphenol A divinyl ether, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, phenoxyethyl (meth) acrylate; polyethylene Glico Di (meth) acrylate, polypropylene di (meth) acrylate, trimethylolethane tri (meth) acrylate, neoventyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipenta (Meth) acrylate after adding ethylene oxide or propylene oxide to polyhydric alcohol such as erythritol hexa (meth) acrylate, hexanediol di (meth) acrylate, tri (acryloyloxyethyl) isocyanurate, chryserin or trimethylolethane Urethane acrylates as described in JP-B-48-417G8, JP-B-50-6034, JP-A-51-37193, JP-A-48-6 Polyfunctional acrylates and methacrylates such as polyester acrylates and epoxy acrylates obtained by reacting an epoxy resin with (meth) acrylic acid, as described in No. 183, JP-B-49-43191, JP-B-52-30490 Can be mentioned.

  In the case of fluorine, examples of suitable resins include fluorine acrylic monomers, fluorine methacrylic monomers, fluorine epoxy monomers, and fluorine vinyl monomers. Specifically, 2,2,2-trifluoroethyl acrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2- (perfluorobutyl) ethyl acrylate, 3-perfluorobutyl-2-hydroxypropyl Acrylate, 2- (perfluorohexyl) ethyl acrylate, 3-perfluorohexyl-2-hydroxypropyl acrylate, 2- (perfluorooctyl) ethyl acrylate, 3-perfluorooctyl-2-hydroxypropyl acrylate, 2- (perfluorohexyl) Fluorodecyl) ethyl acrylate, 2- (perfluoro-3-methylbutyl) ethyl acrylate, 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl acrylate, 2- (perfluoro-5-methylhexyl) ethyl acetate Rate, 3- (perfluoro-5-methylhexyl) -2-hydroxypropyl acrylate, 2- (perfluoro-7-methyloctyl) ethyl acrylate, 3- (perfluoro-7-methyloctyl) -2-hydroxypropyl Acrylate, 1H, 1H, 3H-tetrafluoropropyl acrylate, 1H, 1H, 5H-octafluoropentyl acrylate, 1H, 1H, 7H-dodecafluoroheptyl acrylate, 1H, 1H, 9H-hexadecafluorononyl acrylate, 1H-1 -(Trifluoromethyl) trifluoroethyl acrylate, 1H, 1H, 3H-hexafluorobutyl acrylate, 2,2,3,3,4,4,5,5-octafluorohexane 1,6-diacrylate, 2 , 2,2-trifluoroethyl Methacrylate, 2,2,3,3,3-pentafluoropropyl methacrylate, 2- (perfluorobutyl) ethyl methacrylate, 3-perfluorobutyl-2-hydroxypropyl methacrylate, 2- (perfluorohexyl) ethyl methacrylate, 3 -Perfluorohexyl-2-hydroxypropyl methacrylate, 2- (perfluorooctyl) ethyl methacrylate, 3-perfluorooctyl-2-hydroxypropyl methacrylate, 2- (perfluorodecyl) ethyl methacrylate, 2- (perfluoro-3 -Methylbutyl) ethyl methacrylate, 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl methacrylate, 2- (perfluoro-5-methylhexyl) ethyl methacrylate, 3- ( Perfluoro-5-methylhexyl) -2-hydroxypropyl methacrylate, 2- (perfluoro-7-methyloctyl) ethyl methacrylate, 3- (perfluoro-7-methyloctyl) -2-hydroxypropyl methacrylate, 1H, 1H , 3H-tetrafluoropropyl methacrylate, 1H, 1H, 5H-octafluoropentyl methacrylate, 1H, 1H, 7H-dodecafluoroheptyl methacrylate, 1H, 1H, 9H-hexadecafluorononyl methacrylate, 1H-1- (trifluoromethyl ) Trifluoroethyl methacrylate, 1H, 1H, 3H-hexafluorobutyl methacrylate, 2,2,3,3,4,4,5,5-octafluorohexane 1,6-dimethacrylate, hexafluoroepoxy Bread, 3-perfluorobutyl-1,2-epoxypropane, 3-perfluorohexyl-1,2-epoxypropane, 3-perfluorooctyl-1,2-epoxypropane, 3-perfluorodecyl-1,2 -Epoxypropane, 3- (perfluoro-3-methylbutyl) -1,2-epoxypropane, 3- (perfluoro-5-methylhexyl) -1,2-epoxypropane, 3- (perfluoro-7-methyl Octyl) -1,2-epoxypropane, 3- (2,2,3,3-tetrafluoropropoxy) -1,2-epoxypropane, 3- (1H, 1H, 5H-octafluoropentyloxy) -1, 2-epoxypropane, 3- (1H, 1H, 7H-dodecafluoroheptyloxy) -1,2-epoxypropane, 3- (1H, 1H Monomers such as 9H-hexadecafluorononyloxy) -1,2-epoxypropane, 1,4-bis (2 ′, 3′-epoxypropyl) -perfluoro-n-butane, and the like Can be mentioned.

  It is not particularly limited to any one of these monomers, and a polymer fluororesin may be selected. As a copolymer, Central Glass Co., Ltd. Those similar to 702C, 703C, 704C, 705C, 706C, and 707C may be mentioned.

  The fluorine-type monomer which has a polymerization functional group in the molecule | numerator in a binder component can also be used only by 1 type, and can also be used in combination of 2 or more types. Also, two or more of the above-mentioned acrylates and methacrylates can be used in combination.

  The content of the monomer contained in the resin composition for forming the first layer is 30% by weight or more and 99% by weight or less, preferably 37% by weight with respect to the resin composition forming the first layer. % To 78% by weight is desirable.

  As an energy curing method, it is possible to polymerize by stimulating the initiator by energy such as plasma treatment, heat treatment, radioactivity, ultraviolet rays, etc., but when considering replica molding of a lens or the like, photocuring is preferable. . Specifically usable photopolymerization initiators include, for example, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 1-hydroxy-cyclohexyl-phenyl-ketone, bis ( 2,46, -trimethylbenzoyl) -phenylphosphine oxide, 4-phenylbenzophenone, 4-phenoxybenzophenone, 4,4′-diphenylbenzophenone, 4,4′-diphenoxybenzophenone and the like can be mentioned as suitable ones. . Considering the transparency of the cured resin, it is preferable to use 1-hydroxy-cyclohexyl-phenyl-ketone.

  When used for curing and molding the resin according to the present invention, the amount of photopolymerization initiator added is 0.01% by weight based on the binder component, although it varies depending on the amount of fine particles having absorption in visible light. It is preferable to select in the range of 10.00% by weight or less. A photoinitiator can also be used only by 1 type according to the reactivity with a binder component, and the wavelength of light irradiation, and can also be used in combination of 2 or more types.

(About the second layer)
In the present invention, the high refractive index and low dispersion resin composition for forming the oxygen permeable second layer includes fine particles, monomers, a dispersion solvent, a surface treatment agent, a dispersion composed of a high refractive index and low dispersion material. It consists of a composition containing an agent (surfactant) and a monomer.

  Preferable examples of the high refractive index and low dispersion of the fine particles contained in the resin constituting the second layer of the present invention include aluminum oxide and zirconium oxide. However, this does not limit the use of a material having a high refractive index and low dispersion in the future. Further, when a fluororesin or the like is used as the resin for the second layer, fine particles whose refractive index is higher than the refractive index difference may be unnecessary.

  In addition, it is preferable to use various surface treatment agents and dispersants on the surface of the fine particles in accordance with a solvent in which the monomer serving as the base resin and the fine particles are previously dispersed.

  The average particle size of the fine particles is preferably a particle size that does not adversely affect light transmittance, optical scattering, etc., and is in the range of 1 nm to 100 nm, preferably 2 nm to 30 nm, particularly 2 nm to 20 nm. It is preferable that However, for example, even when the average particle size is 20 nm or less, the particles having a wide particle size distribution and a particle size larger than 30 nm, including the case where the fine particles are aggregated, have a volume fraction of 5% or more of the total fine particles. Greatly affects the optical scattering. In that case, it is preferable to remove unnecessary large fine particles by performing filtration with a filter having pores relatively smaller than the particle size to be removed. The timing of removing the fine particles may or may not depend on whether the fine particles are dispersed in the solvent before the base resin is mixed (fine particle dispersion), the base resin is dissolved in the fine particle dispersion, or the viscosity. The solvent is preferably removed in a solvent-free system of the base resin and fine particles.

  It is desirable to subject the fine particles to surface treatment as necessary. Each surface treatment may be performed at the stage of synthesis and production of fine particles, or may be performed separately after obtaining fine particles alone.

  The volume content of the fine particles made of the transparent conductive material in the resin composition for forming the second layer is 1 vol. % Or more 29 vol. % Or less, preferably 5 vol. % Or more and 23 vol. % Or less is desirable.

  Examples of the dispersion solvent used in the present invention include toluene, benzene, xylene and the like for dissolving the binder component or for dispersing fine particles in the solvent, and for dissolving the surface treatment agent and the dispersant as necessary. Aromatic hydrocarbons, alcohols such as ethanol and isopropanol, alicyclic hydrocarbons such as cyclohexane, acetates such as ethyl acetate and butyl acetate, ketones such as acetone and methyl ethyl ketone, amides such as DMF, DMAc and NMP , Aliphatic hydrocarbons such as hexane and octane, ethyls such as diethyl ether and butyl carbitol, halogenated hydrocarbons such as dichloromethane and carbon tetrachloride, and the like, but are not limited thereto. The dispersion solvent can be selected in accordance with the affinity of the fine particles to be used, the surface treatment agent, and the affinity of the dispersing agent, and only one kind of solvent can be used. It can also be used in combination of more than one type. The dispersion solvent is removed in the process of preparing the resin composition.

  The content of the dispersion solvent contained in the resin composition for forming the second layer is 0.2% by weight or less, preferably 0.05% by weight, based on the resin composition forming the second layer. The following is desirable.

  In the present invention, the following surface treatment agent and dispersant (surfactant) for uniformly dispersing fine particles so as not to aggregate are desirable. In general, when fine particles are dispersed in a solvent, resin, etc. using a surface treatment agent and a dispersant, the dispersion state is completely different depending on the type, amount, molecular weight, polarity, affinity, etc. of the surface treatment agent and dispersant to be added. It is known. As the surface treatment agent and dispersant used in the present invention, pigment derivatives, resin types and activator types can be suitably used. Here, as the surface treating agent and the dispersing agent, cationic, weak cationic, nonionic or amphoteric surfactants are effective. Especially polyester-based, ε-caprolactone-based, polycarboxylate, polyphosphate, hydrostearate, amide sulfonate, polyacrylate, olefin maleate copolymer, acrylic-maleate copolymer, Alkylamine acetates, alkyl fatty acid salts, fatty acid polyethylene glycol esters, silicones, and fluorines can be used. In the present invention, at least one base selected from ammonia and organic amines should be used. Is preferred. Specifically, in the Dispersic series (manufactured by Big Chemie Japan), in the Dispersic 161, 162, 163, 164, in the Solsperse series (manufactured by Zenega), Solsperse 3000, 9000, 17000, 20000, 24000, 41090 Alternatively, in the TAMN series (manufactured by Nikko Chemical Co., Ltd.), there are PO or EO modified products of alkylamines such as TAMN-15. Moreover, a dispersing agent can also be used only by 1 type, and can also be used in combination of 2 or more types.

  The content of the surface treatment agent and the dispersant contained in the resin composition for forming the second layer is roughly divided into the surface treatment agent, the type of the dispersant, the type of fine particles, and the surface area (fine particle diameter) of the fine particles. Depending on the type of dispersion solvent, such as the type of dispersion resin in which the fine particles are mixed. The content of the surface treatment agent and the dispersant is in the range of 0.1% by weight to 25.0% by weight, preferably 4.0% by weight to 20.0% by weight, based on the weight of the fine particles. desirable. If the amount of the dispersant added is more than 25.0% by weight, it causes white turbidity and optical scattering occurs, and the characteristics (refractive index, Abbe number, elastic modulus) of the composition obtained by containing fine particles. Etc.) more than necessary.

  In the present invention, a monomer that is a binder component as a base resin is selected so that the transparent conductive metal oxide fine particles are well-dispersed in a solvent, a surface treatment agent, and a dispersing agent. desirable.

  The monomer is not particularly limited as long as it has one or more double bonds or triple bonds in the molecule. Specific examples of monomers or oligomers of unsaturated group-containing compounds include: 1,4-divinylcyclohexane, 1,4-cyclohexanedimethanol divinyl ether, 4,4-dimethyl-hept-1-ene-6-in, divinylbenzene, 1,6-divinylnaphthalene, N-vinylpyrrolidone, N -Monofunctional acrylates and methacrylates such as vinyl caprolactam, ethoxylated bisphenol A divinyl ether, propoxylated bisphenol A divinyl ether, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, phenoxyethyl (meth) acrylate; polyethylene Glico Di (meth) acrylate, polypropylene di (meth) acrylate, trimethylolethane tri (meth) acrylate, neoventyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipenta (Meth) acrylate after adding ethylene oxide or propylene oxide to polyhydric alcohol such as erythritol hexa (meth) acrylate, hexanediol di (meth) acrylate, tri (acryloyloxyethyl) isocyanurate, chryserin or trimethylolethane Urethane acrylates as described in JP-B-48-417G8, JP-B-50-6034, JP-A-51-37193, JP-A-48-6 Polyfunctional acrylates and methacrylates such as polyester acrylates and epoxy acrylates obtained by reacting an epoxy resin with (meth) acrylic acid, as described in No. 183, JP-B-49-43191, JP-B-52-30490 Can be mentioned.

  The fluorine-type monomer which has a polymerization functional group in the molecule | numerator in a binder component can also be used only by 1 type, and can also be used in combination of 2 or more types. Also, two or more of the above-mentioned acrylates and methacrylates can be used in combination.

  The content of the monomer contained in the resin composition for forming the second layer is 30% by weight or more and 99% by weight or less, preferably 37% by weight with respect to the resin composition forming the second layer. % To 78% by weight is desirable.

  As an energy curing method, it is possible to polymerize by stimulating the initiator by energy such as plasma treatment, heat treatment, radioactivity, ultraviolet rays, etc., but when considering replica molding of a lens or the like, photocuring is preferable. . Specifically usable photopolymerization initiators include, for example, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 1-hydroxy-cyclohexyl-phenyl-ketone, bis ( 2,46, -trimethylbenzoyl) -phenylphosphine oxide, 4-phenylbenzophenone, 4-phenoxybenzophenone, 4,4′-diphenylbenzophenone, 4,4′-diphenoxybenzophenone and the like can be mentioned as suitable ones. . Considering the transparency of the cured resin, it is preferable to use 1-hydroxy-cyclohexyl-phenyl-ketone.

  When used for curing and molding the resin according to the present invention, the amount of photopolymerization initiator added is 0.01% by weight based on the binder component, although it varies depending on the amount of fine particles having absorption in visible light. It is preferable to select in the range of 10.00% by weight or less. A photoinitiator can also be used only by 1 type according to the reactivity with a binder component, and the wavelength of light irradiation, and can also be used in combination of 2 or more types.

(About the preparation process of the optical material as a resin composition)
Next, the preparation process of the optical material as the resin composition in the present invention will be described. A case where a photopolymerizable binder component is used as a representative is described.

  First, an appropriate amount of a surface treatment agent or dispersant suitable for the selected solvent is dissolved, fine particles are added, shear force is applied, the fine particle aggregates are crushed, and the remaining aggregates are removed by centrifugation and filtering to obtain uniform fine particles. A dispersion is obtained. Thereafter, the selected photopolymerizable binder component and photopolymerization initiator are dissolved. When the binder component is dissolved in the fine particle dispersion, it is desirable to add a combination of a solvent, a surface treatment agent, and a dispersant that are less likely to deteriorate the dispersion state of the fine particles due to the addition of the binder component. Moreover, a filtering process can be performed as needed to remove the aggregated fine particles. After complete dissolution, after confirming that the particles are suitably dispersed without precipitation of fine particles, the solvent is removed using an evaporator. At this time, it is desirable to appropriately adjust the degree of vacuum according to the boiling point of the solvent, the amount of residual solvent, and the like. Sudden evaporation and removal of the solvent may deteriorate the degree of aggregation of the fine particles and impair dispersibility. In addition, when removing the solvent by reducing the pressure, it is possible to heat to the extent that the dispersibility is not impaired, if necessary. In this way, the optical material of the present invention is obtained.

  The obtained optical material may contain a residual solvent that cannot be completely removed. If the content is greater than 0.1% by weight, there appears to be an effect of promoting the movement of fine particles during energy curing, and the refractive index gradient (GI) and light scattering increase. Therefore, the content of residual solvent is desirably 0.1% by weight or less. However, if the degree of vacuum is too high, or with heating at the same time as the vacuum, or through a vacuum process for a long time, the monomers such as the surface treatment agent, the dispersant and the binder component added together with the solvent There is a risk of evaporation. Therefore, it is necessary to adjust the degree of pressure reduction, temperature, time, etc. in consideration of individual molecular weight, boiling point, sublimability and the like.

  Next, in the molding of the optical element and the diffractive optical element of the present invention, a process of forming a mold molded body layer by energy curing of the above resin composition using a photopolymerization method is shown.

  When forming the thin first and second layers on the light transmissive material used for the substrate, for example, a glass flat plate is used for the substrate. On the other hand, when a metal material is used in a mold corresponding to a fine diffraction grating structure, a mold is formed by pouring an optical material of a resin composition exhibiting fluidity between the two and suppressing it lightly. The optical material is subjected to photopolymerization while being maintained in that state. The light irradiation used for the photopolymerization reaction is performed using light of a suitable wavelength, usually ultraviolet light or visible light, corresponding to a mechanism resulting from radical generation using a photopolymerization initiator. For example, a light transmissive material used for the substrate, specifically, a raw material body such as a resin composition for preparing an optical material that is molded is uniformly irradiated with light through a glass plate. . The amount of light to be irradiated is appropriately selected according to the mechanism resulting from radical generation using the photopolymerization initiator and according to the content ratio of the contained photopolymerization initiator.

  Subsequently, a second layer that transmits oxygen is stacked. When used as a highly efficient diffractive optical element over the entire visible range, the material used for the second layer is determined by the optical constants of the first layer, and has a high refractive index and low dispersion after curing relative to the first layer. Indicates. As the material for the second layer, a single resin or a mixture of fine particles of zirconia or alumina is used.

  The resin composition of the second layer resin is placed in a mold or glass mold, the polymer molded body (such as a diffraction grating) of the first layer is lightly pressed, and the optical material is kept in that state. Perform photopolymerization. The light irradiation used for the photopolymerization reaction is performed using light of a suitable wavelength, usually ultraviolet light or visible light, corresponding to a mechanism resulting from radical generation using a photopolymerization initiator. For example, a light-transmitting material used for the substrate, specifically, from a transparent substrate side or glass mold side of the first layer, to a raw material body such as a monomer for preparing an optical material, Perform light irradiation uniformly. The amount of light to be irradiated is appropriately selected according to the mechanism resulting from radical generation using the photopolymerization initiator and according to the content ratio of the contained photopolymerization initiator.

  After curing the resin composition of the second layer by the above method, an optical element is obtained by releasing from the mold or glass mold.

  If the thickness of the second layer is too thick, the oxygen permeability is reduced, and the effect as an oxygen permeable layer is lost.

  Next, the present invention will be described with reference to the drawings.

  FIG. 1A is a schematic diagram showing an embodiment of the multilayer diffractive optical element of the present invention, in which an upper diagram is a plan view and a lower diagram is a sectional view taken along line AA. In FIG. 1A, a multilayer diffractive optical element 100 has a diffraction grating shape made of a resin formed by energy curing a resin composition containing fine particles and a monomer made of a transparent conductive material on a transparent substrate 3. And a second layer 1 having a diffraction grating shape on at least one surface that is permeable to oxygen are laminated so that their diffraction grating shapes face each other. The first layer 2 is made of a low refractive index and high dispersion material, and the second layer 1 is made of a high refractive index and low dispersion material. The second layer is open to the atmosphere and is a space for supplying oxygen.

  By using the multilayer diffractive optical element of the present invention, a plurality of layers made of materials having different refractive index wavelength dispersions are laminated on a substrate, and the design is made to increase the diffraction efficiency of a specific order (design order) over the entire use wavelength range, In addition, it is possible to provide a diffractive optical element that does not change in characteristics due to visible light or ultraviolet light.

  FIG. 1B is a schematic diagram showing another embodiment of the multilayer diffractive optical element of the present invention. FIG. 1 (b) shows another material of a multilayer diffractive optical element, specifically a relatively high refractive index and low dispersion material, instead of a metal material in a mold corresponding to a fine diffraction grating structure. The one formed into a structure is used as a transparent substrate (glass substrate, glass lens, etc.), and the first layer 2 is formed thereon.

  By using the multilayer diffractive optical element having the configuration shown in FIG. 1B, a plurality of layers made of materials having different refractive index wavelength dispersions are stacked on a substrate, and a diffraction efficiency of a specific order (design order) is obtained over the entire use wavelength range. It is possible to provide a diffractive optical element that is designed to be high and that does not change in characteristics due to visible light or ultraviolet light.

FIG. 1 (c) is a schematic view showing another embodiment of the multilayer diffractive optical element of the present invention. In FIG. 1C, a space 5 for supplying oxygen is provided on the second layer 1 of FIG. The height of the space for supplying oxygen (distance between the second layer 1 and the transparent substrate 3) is 50 μm or more and 5 mm or less, and the concentration of oxygen contained in the space is 10% or more and 100% or less (volume%). The concentration of water contained in the space is preferably 230 g / m ³ (25% relative humidity 10%) or less. In order to keep the concentration of water in the space at 230 g / m ³ (relative humidity 10% at 25 ° C.) or less, the end of the space 5 is blocked by the spacer 4 and the sealant 6 to prevent moisture from entering from the outside. Yes. Examples of the sealant include a sealing material OE-6450 A / B (Toray Dow Corning).

  By using the multilayer diffractive optical element having the configuration shown in FIG. 1C in the present invention, a plurality of layers made of materials having different refractive index wavelength dispersions are laminated on a substrate, and a specific order (design order) is used in the entire wavelength range of use. Therefore, it is possible to provide a diffractive optical element that is designed to increase the diffraction efficiency of the light source and that has no change in characteristics due to visible light or ultraviolet light and no change in characteristics due to moisture absorption.

FIG. 1 (d) is a schematic view showing another embodiment of the multilayer diffractive optical element of the present invention. FIG. 1D shows a structure in which a space 5 for supplying oxygen is provided on the first layer 2 of the multilayer diffractive optical element shown in FIG. The height of the space for supplying oxygen (distance between the first layer 2 and the transparent substrate 3) is 50 μm or more and 5 mm or less, and the concentration of oxygen contained in the space is 10% or more and 100% or less (volume%). The concentration of water contained in the space is preferably 230 g / m ³ (25% relative humidity 10%) or less. In order to keep the moisture concentration in the space at 230 g / m ³ (relative humidity 10% at 25 ° C.) or less, as shown in FIG. Blocks moisture from entering.

  By using the multilayer diffractive optical element having the configuration shown in FIG. 1D, a plurality of layers made of materials having different refractive index wavelength dispersions are stacked on the substrate, and the diffraction efficiency of a specific order (design order) in the entire use wavelength range. Thus, it is possible to provide a diffractive optical element that is designed to have a high height and that has no change in characteristics due to visible light or ultraviolet light and no change in characteristics due to moisture absorption.

  The preparation of the optical material in the present invention will be specifically described below.

Reference example 1
[Adjustment of Low Refractive Index High Dispersion Material 11]
First, 51.63 g of a fine particle dispersion in which indium tin oxide (ITO) is dispersed in a xylene solvent (indium tin oxide concentration: 9.96 w% with an average particle size of 20 nm, 2.19 w% dispersant) is ultraviolet-cured. As a type acrylic resin, tris (2-acryloxyethyl) isocyanurate 20 w%, pentaerythritol triacrylate 25 w%, dicyclopentenyloxyethyl methacrylate 40 w%, urethane-modified polyester acrylate 13 w%, 1-hydroxycyclohexyl phenyl ketone 2 w % Of the mixture was mixed with 3.72 g. This mixed solution was put into an evaporator, and finally the xylene solvent was removed at an oil bath temperature of 45 ° C. and a set atmospheric pressure of 2 hPas for 15 hours to prepare a low refractive index and high dispersion material 11.
The particle size of indium tin oxide (ITO) was measured with a laser particle size distribution meter (ELS: Otsuka Electronics).

  Moreover, the low refractive index high dispersion material 11 was baked by TGA (manufactured by Perkin Elmer), and the amount of inorganic solid content in the low refractive index high dispersion material 11 was quantified. It was 51.2% by weight.

  The residual solvent (xylene) was measured by gas chromatography (5890 series II: Hewlett Packard) and found to be 0.015 w%.

[Adjustment of High Refractive Index Low Dispersion Material 21]
160.2 g of a fine particle dispersion in which zirconium oxide is dispersed in a toluene solvent (zirconium oxide concentration of 10.11 w% with an average particle size of 10 nm, a dispersant amount of 2.27 w%) is 160.2 g, and tris (2 -Acryloxyethyl) isocyanurate 20 w%, pentaerythritol triacrylate 25 w%, dicyclopentenyloxyethyl methacrylate 40 w%, urethane modified polyester acrylate 13 w%, 1-hydroxycyclohexyl phenyl ketone 2 w% 9.41 g did. This mixed solution was put into an evaporator, and finally the toluene solvent was removed at an oil bath temperature of 45 ° C. and a set atmospheric pressure of 3 hPas for 15 hours to prepare a high refractive index and low dispersion material 21.

  The particle size of zirconium oxide was measured with a laser particle size distribution meter (ELS: Otsuka Electronics).

  Further, the high refractive index and low dispersion material 21 was baked by TGA (manufactured by Perkin Elmer), and the amount of inorganic solid content in the high refractive index and low dispersion material 21 was quantified. It was 53.7% by weight.

  The residual solvent (xylene) was measured by gas chromatography (5890 series II: Hewlett Packard), and was 0.005 w% or less and below the detection limit.

(Evaluation of optical properties)
The optical properties of the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21 were evaluated as follows.

<Refractive index>
The refractive index of each optical element was measured by preparing a sample as follows.

FIG. 2 is a schematic diagram illustrating a method for producing a sample for refractive index measurement. First, as shown in FIG. 2A, a spacer 10 having a thickness of 12.5 μm and a measurement material 8 (low refractive index and high dispersion) are formed on a high refractive glass (S-TIH11: manufactured by OHARA) 7 having a thickness of 1 mm. Material 11) was placed. A quartz glass 9 having a thickness of 1 mm was placed thereon via a spacer 10 to spread the measurement material 8. This was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under the condition (26J) of 20 mW / cm ² (illuminance through quartz glass) and 1300 seconds, and the measurement material 8 was cured. After curing, the quartz glass 9 was peeled off and annealed at 80 ° C. for 72 hours. Thereafter, as shown in FIG. 2 (b), a spacer 11 having a thickness of 50 μm and a measurement material 12 (high refractive index low dispersion material 21) are arranged, and a quartz glass 9 having a thickness of 1 mm is placed on the spacer 11 through the spacer 11 and measured. The material 12 was spread and used as a sample. This was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under a condition (26J) of 20 mW / cm ² (illuminance through quartz glass) and 1300 seconds, and the measurement material 12 was cured. After curing, the quartz glass 9 was peeled off and annealed at 80 ° C. for 72 hours to obtain a sample for refractive index measurement. FIG. 2C shows the configuration of the measurement sample.

  The cured sample was measured using a refractometer (KPR-30, Shimadzu Corporation) from the side of the high refractive index glass 4 with a g-line of 435.8 nm, an f-line of 486.1 nm, an e-line of 546.1 nm, and a d-line of 587. The refractive index of .6 nm and c-line 656.3 nm was measured. Further, the Abbe number was calculated from the measured refractive index.

<Multilayer diffractive optical element>
Next, a diffractive optical shape was formed with the low refractive index and high dispersion material 11, and a multilayer diffractive optical element was prepared by laminating the high refractive index and low dispersion material 21 without making a space, and evaluated.

<Creation of multilayer diffraction grating>
3 and 4 are schematic views showing a method for producing a multilayer diffractive optical element for evaluating diffraction efficiency. First, as shown in FIG. 3A, a measurement material 8 (low refractive index high dispersion material 11) was placed on a diffraction grating-shaped mold 13, and a 2 mm flat glass 14 was placed thereon. High pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) was irradiated under conditions of 14.2 mW / cm ² , 211 seconds and 20 mW / cm ² , 600 seconds, and annealed in the atmosphere at 80 ° C. for 72 hours. Then, a diffraction grating was created. The grating height measured after annealing was 11.7 μm, and the pitch was 80 μm (FIG. 3B).

Next, the measurement material 8 molded on the flat glass 14 is set on the forming jig 16 together with the flat glass 14, and then the measurement material 12 (high refractive index low dispersion material 21) is dropped on the measurement material 8 ( FIG. 4 (a)). A flat glass 14 was placed thereon, and a sample was spread out so that the thickness of the resin was 30 μm higher than the height of the lattice. (FIG. 4B). This sample, and conditions of 14.2 mW ^/ cm 2, 211 seconds, irradiated with a high pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS (Ltd.)) under conditions of 20 mW ^/ cm 2, 600 seconds to cure the samples. Thereafter, the flat glass 14 was removed and annealed at 80 ° C. for 72 hours to produce a multilayer diffractive optical element. FIG. 4C shows the configuration of the multilayer diffraction grating.

<Evaluation of diffraction efficiency>
The diffraction efficiency is determined by applying the spot light to the multilayer diffractive optical element, closely contacting the light receiving portion, measuring the light amount of all transmitted light, and then measuring the light amount of the designed order (first-order diffracted light). The ratio (design order light quantity / total transmitted light quantity) was defined as diffraction efficiency.

<Evaluation of light resistance>
A refractive index measurement sample and a multilayer diffractive optical element prepared from the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21 are measured at 5 mW (300 x) using a light resistance tester (Xenon Weather Meter X75 Suga Test Instruments Co., Ltd.). To 400 nm irradiation intensity) for 100 hours. Thereafter, the refractive index of the refractive index measurement sample and the diffraction efficiency of the multilayer diffractive optical element were measured.

<Evaluation of high temperature and high humidity durability>
A refractive index measurement sample and a multilayer diffractive optical element prepared from the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21 are heated at 60 ° C. with a high temperature and high humidity tester (compact environment tester IW241, manufactured by Yamato Scientific). A high temperature and high humidity test was conducted at 90% for 500 hours. Thereafter, the refractive index of the refractive index measurement sample and the diffraction efficiency of the multilayer diffractive optical element were measured.

<Evaluation results>
(1) Initial Evaluation Results The multilayer diffractive optical element 11 made from the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21 has a diffraction efficiency of 99% or more in the entire visible range.
_{n C} is the refractive index from n _g, ν _d is Abbe number, theta _gF represents a partial dispersion ratio (secondary dispersion). (Refractive index and optical constant)
<Low refractive index high dispersion material 11>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6037,1.5916,1.5809,1.5740,1.5640)
(Ν _d , θ _gF ) = (20.8, 0.44)
<High refractive index low dispersion material 21>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.641,1.633,1.627,1.623,1.619)
(Ν _d , θ _gF ) = (43.9, 0.57)

(2) Results of light resistance evaluation The multilayer diffractive optical element 11 made of the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21 has a diffraction efficiency of 99% or more in the entire visible region, and there is a large variation with respect to the initial stage. Absent.
(Refractive index and optical constant)
<Low refractive index high dispersion material 11>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6027,1.5909,1.5802,1.5733,1.5632)
(Ν _d , θ _gF ) = (20.7, 0.43)
The refractive index variation with respect to the initial value was -0.0007 to -0.0010.
<High refractive index low dispersion material 21>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6416,1.6336,1.6271,1.6237,1.6196)
(Ν _d , θ _gF ) = (43.9, 0.57)
The refractive index variation was +0.0003 to +0.0005 with respect to the initial value.

(3) As a result of the high temperature and high humidity durability evaluation, the multilayer diffractive optical element 11 made of the low refractive index and high dispersion material 11 and the high refractive index and low dispersion material 21 has a diffraction efficiency of 98% or more in the entire visible region, compared with the initial value. Varies from 1 to 2%.
(Refractive index and optical constant)
<Low refractive index high dispersion material 11>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6015,1.5895,1.5787,1.5720,1.5621)
(Ν _d , θ _gF ) = (20.9, 0.44)
The refractive index variation with respect to the initial value was -0.0019 to -0.0022.
<High refractive index low dispersion material 21>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6364,1.6285,1.6219,1.6186,1.6143)
(Ν _d , θ _gF ) = (43.7, 0.56)
The refractive index variation with respect to the initial value was -0.0046 to -0.0049.

Example 1
Unlike Reference Example 1, a refractive index evaluation sample and a space in which oxygen is supplied onto the multilayer diffractive optical element (the distance between the measurement material 12 and 9 quartz glass 9 in FIG. 5) are 50 μm or more and 5 mm or less. The surroundings were sealed with a sealant so that moisture did not enter.

(Evaluation of optical properties)
The optical properties of the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21 were evaluated as follows.

<Preparation of a sample for refractive index measurement>
The refractive index of each optical element was measured by preparing a sample as follows.

First, as shown in FIG. 2A, a spacer 10 having a thickness of 12.5 μm and a measurement material 8 (low refractive index and high dispersion) are formed on a high refractive glass (S-TIH11: manufactured by OHARA) 7 having a thickness of 1 mm. Material 11) was placed. A quartz glass 9 having a thickness of 1 mm was placed thereon via a spacer 10 to spread the measurement material 8. This was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under the condition (26J) of 20 mW / cm ² (illuminance through quartz glass) and 1300 seconds, and the measurement material 8 was cured. After curing, the quartz glass 9 was peeled off and annealed at 80 ° C. for 72 hours. Thereafter, as shown in FIG. 2 (b), a spacer 11 having a thickness of 50 μm and a measurement material 12 (high refractive index low dispersion material 21) are arranged, and a quartz glass 9 having a thickness of 1 mm is placed on the spacer 11 through the spacer 11 and measured. The material 12 was spread and used as a sample. This was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under a condition (26J) of 20 mW / cm ² (illuminance through quartz glass) and 1300 seconds, and the measurement material 12 was cured. After curing, the quartz glass 9 was peeled off and annealed at 80 ° C. for 72 hours.

  After that, as shown in FIG. 5, the quartz glass 9 is placed through a spacer 17 of 75 μm to 5 mm, and a sealing agent 18 (LED sealing material OE-6450A / B) is placed, and 80 ° C. for 24 hours. The refractive index measurement sample was prepared by curing the sealant 18 and providing a space 19 for supplying oxygen of 25 μm to 5 mm.

The refractive index measurement sample configuration is shown in FIG.
-Refractive index measurement sample 12-0 made the refractive index measurement sample which arranged the space which supplies oxygen of 25 micrometers using 75 micrometer spacer 17. FIG.
-The refractive index measurement sample 12-1 made the multi-refractive-index measurement sample which arranged the space which supplies oxygen of 50 micrometers using the 100 micrometers spacer 17. FIG.
The refractive index measurement sample 12-2 was a multi-refractive index measurement sample having a space for supplying 100 μm oxygen using a 150 μm spacer 17.
The refractive index measurement sample 12-3 was a multi-refractive index measurement sample having a space for supplying 450 μm of oxygen using a 500 μm spacer 17.
-The refractive index measurement sample 12-4 made the multi-refractive-index measurement sample which arranged the space which supplies 950 micrometers oxygen using the 1 mm spacer 17. FIG.
-As the refractive index measurement sample 12-5, a 5 mm spacer 17 was used to prepare a multi-refractive index measurement sample in which a space for supplying approximately 5 mm of oxygen was disposed.

  The cured sample was measured using a refractometer (KPR-30, Shimadzu Corporation) from the side of the high refractive index glass 4 with a g-line of 435.8 nm, an f-line of 486.1 nm, an e-line of 546.1 nm, and a d-line of 587. The refractive index of .6 nm and c-line 656.3 nm was measured. Further, the Abbe number was calculated from the measured refractive index.

<Creation 12 of Multilayer Diffraction Grating>
As shown in FIG. 3, first, a measurement material 8 (low refractive index high dispersion material 11) was placed on a diffraction grating-shaped mold 13, and a 2 mm glass substrate 14 was placed thereon. High pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) was irradiated under conditions of 14.2 mW / cm ² , 211 seconds and 20 mW / cm ² , 600 seconds, and annealed in the atmosphere at 80 ° C. for 72 hours. A diffraction grating was created.

  The grating height measured after annealing was 11.7 μm, and the pitch was 80 μm.

Next, as shown in FIG. 4, the measurement material 8 formed on the flat glass 14 is set together with the flat glass 14 on a forming jig 16, and then the measurement material 12 (high refractive index, low dispersion) is formed on the measurement material 8. Material 21) was added dropwise (FIG. 4 (a)). A flat glass 14 was placed thereon, and a sample was spread out so that the thickness of the resin was 30 μm higher than the height of the lattice. (FIG. 4B). This sample was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under the conditions of 14.2 mW / cm ² , 211 seconds and 20 mW / cm ² , 600 seconds, and after curing the sample, The glass 14 was removed and annealed at 80 ° C. for 72 hours to prepare a multilayer diffractive optical element. FIG. 4C shows the configuration of the multilayer diffraction grating.

  Thereafter, the flat glass 14 is placed through a spacer 17 of 75 μm to 5 mm, a sealing agent 18 (LED sealing material OE-6450A / B) is disposed, and cured at 80 ° C. for 24 hours, and from 50 μm to 5 mm. A multilayer diffractive optical element having a space 19 for supplying oxygen was prepared. FIG. 6 shows an outline of the configuration of the multilayer diffractive optical element.

The structure of the multilayer diffractive optical element is shown below.
The multilayer diffraction grating 12-0 was a multilayer diffraction optical element having a space for supplying 25 μm oxygen using a 75 μm spacer 17 (Reference Example 2) .
A multilayer diffraction optical element having a space for supplying 50 μm oxygen was prepared using a 100 μm spacer 17 as the multilayer diffraction grating 12-1.
The multilayer diffraction grating 12-2 is a multilayer diffraction optical element having a space for supplying 100 μm oxygen using a 150 μm spacer 17.
The multilayer diffraction grating 12-3 is a multilayer diffraction optical element having a space for supplying 450 μm oxygen using a 500 μm spacer 17.
The multilayer diffraction grating 12-4 is a multilayer diffraction optical element having a space for supplying 950 μm oxygen using a 1 mm spacer 17.
A multilayer diffractive optical element having a space for supplying oxygen of about 5 mm was prepared using a 5 mm spacer 17 as the multilayer diffraction grating 12-5.

<Evaluation of diffraction efficiency> According to the method of Reference Example 1 <Evaluation of light resistance>
According to the method of Reference Example 1 <Evaluation of high temperature and high humidity durability>
Follow the method of Reference Example 1

<Evaluation results>
(1) Initial evaluation results The multilayer diffraction optical elements 12-0, 12-1, 12-2, 12-3, 12-4, and 12-5 have a diffraction efficiency of 99% or more in the entire visible range.
(Refractive index and optical constant)
Refractive index measurement sample: results of 12-0, 12-1, 12-2, 12-3, 12-4, 12-5 <Low refractive index high dispersion material 11>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6037,1.5916,1.5809,1.5740,1.5640)
(Ν _d , θ _gF ) = (20.9, 0.44)
Δn = ± 0.0003, and no significant difference is observed.
<High refractive index low dispersion material 21>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.641,1.633,1.627,1.623,1.619)
(Ν _d , θ _gF ) = (43.9, 0.57)
Δn = ± 0.0003, and no significant difference is observed.

(2) Light resistance evaluation results The multilayer diffractive optical elements 12-1, 12-2, 12-3, 12-4, and 12-5 have a diffraction efficiency of 99% or more in the entire visible region, and there is no great variation with respect to the initial stage. .
The multilayer diffractive optical element 12-0 has a diffraction efficiency of 98% or more in the entire visible region and varies by 1 to 2% from the initial stage.
(Refractive index and optical constant)
The refractive index measurement sumps 12-1, 12-2, 12-3, 12-4, and 12-5 show that the fluctuations of the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21 are Δn relative to the initial values. = ± 0.0003, no significant change.
(Reference Example 2)
In the refractive index measurement sump 12-0, the fluctuation of the high refractive index and low dispersion material 21 does not change greatly as Δn = −0.0002 with respect to the initial value.
<Low refractive index high dispersion material 11>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6019,1.5898,1.5786,1.5714,1.5606)
(Ν _d , θ _gF ) = (19.6, 0.42)
It is large with Δn = −0.0018 to −0.0034 with respect to the initial stage.

(3) Results of high temperature and high humidity durability evaluation The multilayer diffractive optical elements 12-0, 12-1, 12-2, 12-3, 12-4, and 12-5 have a diffraction efficiency of 99% or more in the entire visible range. There is no significant change from the initial stage.
(Refractive index and optical constant)
The refractive index measurement sumps 12-0, 12-1, 12-2, 12-3, 12-4, and 12-5 have initial values of fluctuations in the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21. In contrast, Δn = ± 0.0003 is not significantly changed.

Comparative Example 1
Unlike Reference Example 1, the quartz glass 9 and the flat glass 14 were not removed when the sample for refractive index measurement and the multilayer diffractive optical element were prepared.

<Preparation of Refractive Index Measurement Sample 13>
The refractive index of each optical element was measured by preparing a sample as follows.

First, as shown in FIG. 2A, a spacer 10 having a thickness of 12.5 μm and a measurement material 8 (low refractive index and high dispersion) are formed on a high refractive glass (S-TIH11: made by Hoya) 7 having a thickness of 1 mm. Material 11) was placed. A quartz glass 9 having a thickness of 1 mm was placed thereon via a spacer 10 to spread the measurement material 8. This was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under the condition (26J) of 20 mW / cm 2 (illuminance through quartz glass) and 1300 seconds, and the measurement material 8 was cured. After curing, the quartz glass 9 is peeled off and annealed at 80 ° C. for 72 hours, and then a 50 μm spacer 11 and a measurement material 12 (high refractive index low dispersion material 21) are arranged as shown in FIG. A quartz glass 9 having a thickness of 1 mm was placed thereon via a spacer 11, and a measurement material 12 was spread and used as a sample. This was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under a condition (26J) of 20 mW / cm ² (illuminance through quartz glass) and 1300 seconds, and the measurement material 12 was cured.

Unlike the reference example 1, after curing, the quartz glass 9 was not peeled off and annealed at 80 ° C. for 72 hours as a measurement sample.

  FIG. 7 shows the configuration of the measurement sample.

  The cured sample was measured using a refractometer (KPR-30, Shimadzu Corporation) from the side of the high refractive index glass 4 with a g-line of 435.8 nm, an f-line of 486.1 nm, an e-line of 546.1 nm, and a d-line of 587. The refractive index of .6 nm and c-line 656.3 nm was measured. Further, the Abbe number was calculated from the measured refractive index.

<Multilayer diffractive optical element>
Next, a diffractive optical shape was formed with the low refractive index and high dispersion material 11, and the high refractive index and low dispersion material 21 was laminated to make a multilayer diffractive optical element 13 without making a space, and the evaluation was performed.

<Creation of multilayer diffraction grating 13>
As shown in FIG. 3, first, a measurement material 8 (low refractive index high dispersion material 11) was placed on a diffraction grating-shaped mold 13, and a 2 mm glass substrate 14 was placed thereon. High pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) was irradiated under conditions of 14.2 mW / cm ² , 211 seconds and 20 mW / cm ² , 600 seconds, and annealed in the atmosphere at 80 ° C. for 72 hours. A diffraction grating was created.

The grating height measured after annealing was 12 μm, and the pitch was 80 μm.
Since the evaluation result of the refractive index is different from that of Reference Example 1, the grating height of the diffraction grating is optimized based on the measurement result of the refractive index.

Next, as shown in FIG. 4, the measurement material 8 formed on the flat glass 14 is set together with the flat glass 14 on a forming jig 16, and then the measurement material 12 (high refractive index, low dispersion) is formed on the measurement material 8. Material 21) was added dropwise (FIG. 4 (a)). A flat glass 14 was placed thereon, and a sample was spread out so that the thickness of the resin was 30 μm higher than the height of the lattice. (FIG. 4B). The sample was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under the conditions of 14.2 mW / cm ² , 211 seconds and 20 mW / cm ² , 600 seconds to cure the sample. After curing, unlike in Reference Example 1, the flat glass 14 was not removed, and annealing was performed at 80 ° C. for 72 hours to prepare a multilayer diffractive optical element. FIG. 8 shows the configuration.

<Evaluation of diffraction efficiency>
The method of Reference Example 1 is applied.
<Evaluation of light resistance>
According to the method of Reference Example 1 <Evaluation of high temperature and high humidity durability>
Follow the method of Reference Example 1

<Evaluation results>
(1) Initial Evaluation Results The multilayer diffractive optical element 13 made from the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21 has a diffraction efficiency of 99% or more in the entire visible range.
(Refractive index and optical constant)
<Low refractive index high dispersion material 11>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6009,1.5888,1.5776,1.5704,1.5596)
(Ν _d , θ _gF ) = (19.6, 0.42)
Δn = −0.0028 to −0.0044 with respect to Reference Example 1.
<High refractive index low dispersion material 21>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6364,1.6285,1.6220,1.6186,1.6145)
(Ν _d , θ _gF ) = (44.3, 0.57)
It was (DELTA) n = -0.0045--0.0048 with respect to the reference example 1.

(2) Results of Light Resistance Evaluation The multilayer diffractive optical element 13 made from the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21 has a diffraction efficiency of 98% or more in the entire visible range, which is 1 to 2 from the initial stage. %fluctuate.
(Refractive index and optical constant)
<Low refractive index high dispersion material 11>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.5997,1.5874,1.5755,1.5683,1.5572)
(Ν _d , θ _gF ) = (18.8, 0.41)
The refractive index variation with respect to the initial value was -0.0011 to -0.0025.
<High refractive index low dispersion material 21>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6365,1.6286,1.6220,1.6187,1.6146)
(Ν _d , θ _gF ) = (44.3, 0.57)
The refractive index variation was +0.0001 with respect to the initial value.

(3) Results of high temperature and high humidity durability evaluation The multilayer diffractive optical element 13 made from the low refractive index high dispersion material 11 and the high refractive index low dispersion material 21 has a diffraction efficiency of 99% or more in the entire visible region, compared with the initial value. There are no major fluctuations.
(Refractive index and optical constant)
<Low refractive index high dispersion material 11>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6009,1.5889,1.5777,1.5704,1.5597)
(Ν _d , θ _gF ) = (19.6, 0.41)
The refractive index variation was 0.0000 to +0.0001 with respect to the initial value.
<High refractive index low dispersion material 21>
Refractive index _{(n g, n F, n} e, n d, n C) = (1.6364,1.6285,1.6220,1.6186,1.6145)
(Ν _d , θ _gF ) = (44.3, 0.57)
There was almost no refractive index fluctuation with respect to the initial stage.

From the results of the above Examples , Reference Examples and Comparative Examples, the following can be understood.

  In Comparative Example 1, the resin composition containing the ITO fine particles and the monomer was cured by irradiating with ultraviolet rays, and the low refractive index and high dispersion material 11 (first layer) and the high refractive index and low dispersion material 21 ( The second layer) is sealed with quartz glass 9 and flat glass 14 to produce a multilayer diffractive optical element in which the supply of oxygen is cut off. Under the condition where the supply of oxygen is cut off, radicals are generated by the photochemical reaction of the resin with ultraviolet rays. The generated radicals are trapped in the ITO fine particles, and the ITO is reduced by the radicals, and the optical characteristics such as refractive index and light absorption are changed and influenced.

  In the initial state, it is possible to achieve a diffraction efficiency of 99% or more in the entire visible range by correcting the grating height in consideration of the change in refractive index. However, when the refractive index variation is −0.0011 to −0.0025 in the same situation as described above in the light resistance test or the like, the diffraction efficiency is 98% or more and deteriorates.

On the other hand, the multilayer diffractive optical element in which the low-refractive index high-dispersion material 11 (first layer) and the high-refractive index low-dispersion material 21 (second layer) in Example 1 and Reference Example 1 are stacked has a high refractive index and low refractive index. A space for supplying oxygen is provided on the dispersion material 21 (second layer). For this purpose, the second layer takes in oxygen in the atmosphere and makes oxygen contact with the ITO material of the first layer, thereby eliminating the radicals trapped in the ITO fine particles by oxygen and oxidizing the reduced ITO. Return to the original state. As a result, the optical characteristics such as refractive index and light absorption are less changed in the light resistance test.

  The present invention can provide a diffractive optical element that has no change in characteristics due to visible light or ultraviolet light and no change in characteristics due to moisture absorption. Thereby, it can utilize for imaging optical systems, such as an optical element, a diffractive optical element, a multilayer diffractive optical element, and an optical system, especially a camera, a video camera.

1 Second layer (high refractive index, low dispersion layer)
2 First layer (low refractive index high dispersion layer)
3 Transparent substrate layer 4 Spacer 5 Space for supplying oxygen 6 Sealant 7 High refractive glass (back side)
8 Measurement material 9 Quartz glass (irradiation side)
DESCRIPTION OF SYMBOLS 10 Spacer 11 Spacer 12 Measuring material 13 Mold 14 Glass 15 Mold release jig 16 Molding jig 17 Spacer 18 Sealant 19 Space for supplying oxygen 100 Multilayer diffractive optical element 110 Multilayer diffractive optical element 120 Multilayer diffractive optical element 130 Multilayer Diffractive optical element

Claims (14)

An optical element having a resin layer between two transparent substrates,
On one transparent substrate, a first layer formed of a resin containing 1% by volume to 29% by volume of indium tin oxide (ITO) fine particles and a second layer that transmits oxygen are laminated. And
A closed space for supplying oxygen having a height of 50 μm or more and 5 mm or less is provided between the second layer and the other transparent substrate ,
The optical element according to claim 1, wherein the oxygen concentration in the closed space for supplying oxygen is 10% by volume or more and 100% by volume or less . An optical element having a resin layer between two transparent substrates,
On one transparent substrate, it has a first layer formed of a resin containing 1% by volume or more and 29% by volume or less of indium tin oxide (ITO) fine particles,
A closed space for supplying oxygen having a height of 50 μm or more and 5 mm or less is provided between the first layer and the other transparent substrate ,
The optical element according to claim 1, wherein the oxygen concentration in the closed space for supplying oxygen is 10% by volume or more and 100% by volume or less .   2. The optical element according to claim 1, wherein the first layer is a low refractive index and high dispersion material, and the second layer is a high refractive index and low dispersion material. The optical element according to any one of claims 1 to 3 concentrations of water contained pre Symbol oxygen in the space supplied is equal to or is 230 g / m ³ or less. The optical element according to any one of claims 1 to 4 , wherein an average particle diameter of the fine particles of the transparent conductive substance is 1 nm or more and 100 nm or less. The first layer and the second layer are energy curable resins, and the energy curable resin is a radical curable resin having at least one selected from an acrylic resin, a vinyl resin, and an epoxy resin. the optical element according to claim 1 or 3, characterized in that. The two transparent substrates, the optical element according to any one of claims 1 to 6, characterized in that a glass substrate or a glass lens substrate. A multilayer diffractive optical element in which a resin layer is provided between two transparent substrates,
A transparent substrate is formed of a resin containing fine particles of indium tin oxide (ITO) on one transparent substrate, and has a first grating layer having a diffraction grating shape and a diffraction grating shape on at least one surface that transmits oxygen. And the second layer having the first layer and the second layer are laminated so that the diffraction grating shapes thereof are opposed to each other,
Between the second layer and the other transparent substrate, a closed space for supplying oxygen having a height of 50 μm or more and 5 mm or less is provided ,
The multilayer diffractive optical element according to claim 1, wherein the oxygen concentration in the closed space for supplying oxygen is 10% by volume to 100% by volume . A multilayer diffractive optical element in which a resin layer is provided between two transparent substrates,
It is formed of a resin containing fine particles of indium tin oxide (ITO) on one transparent substrate having a diffraction grating shape and made of a high refractive and low dispersion material, and has a diffraction grating shape on at least one surface. 1 layer is laminated so that the diffraction grating shape of the first transparent substrate and the first layer are opposed to each other,
A closed space for supplying oxygen having a height of 50 μm or more and 5 mm or less is provided between the first layer and the other transparent substrate ,
The multilayer diffractive optical element according to claim 1, wherein the oxygen concentration in the closed space for supplying oxygen is 10% by volume to 100% by volume . 9. The multilayer diffractive optical element according to claim 8 , wherein the first layer is a low refractive index and high dispersion material, and the second layer is a high refractive index and low dispersion material. Multilayer diffractive optical element according to any one of claims 8 to 10 concentrations of the water contained in the enclosed space for supplying the oxygen, characterized in that it is 230 g / m ³ or less. The multilayer diffractive optical element according to any one of claims 8 to 11 , wherein an average particle diameter of the fine particles of the transparent conductive material is 1 nm or more and 100 nm or less. The first layer and the second layer are energy curable resins, and the energy curable resin is a radical curable resin that is at least one selected from an acrylic resin, a vinyl resin, and an epoxy resin. The multilayer diffractive optical element according to claim 8 or 10 , wherein: The multilayer diffractive optical element according to any one of claims 8 to 13 , wherein the two transparent substrates are glass substrates or glass lens substrates.

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