JP5773579B2 - Multilayer diffractive optical element - Google Patents

Description

  The present invention relates to an energy curable resin composition, an optical material, and a multilayer diffractive optical element, and more particularly to a multilayer diffractive optical element used for a camera, a video, and the like, and an optical material used therefor.

  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 beam of the design order and causes flare.

  In Patent Document 1, a relatively low refractive index and high dispersion optical material and a high refractive index and low dispersion optical material are used to concentrate a light beam in a working wavelength region to a specific order (hereinafter referred to as a design order). Therefore, 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 1.32 <n _d < 1.53) and the refractive index dispersion is high (Abbe's number "[nu _d" is 14 <ν _d <35) and low second-order dispersion characteristic ( "theta _gF" is 0.34 <θ _gF <0.47) nature By using this material, the diffraction efficiency in the entire visible region can be improved.

  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, transparent conductive metal oxides, such as ITO, are disclosed as a transparent conductive metal oxide. Further, a fluorine-based monomer is disclosed as a low refractive index binder resin.

JP 2009-197217 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

  Low refractive index and high dispersion optical material is obtained by curing with UV light a composite material in which fluorine monomer as a low refractive index binder resin and fine particles of transparent conductive metal oxide such as ITO are mixed and dispersed. can get.

  However, when the low refractive index and high dispersion material is cured with ultraviolet rays, a large gradient of refractive index (GI: Graded-Index) occurs due to the transparent conductive metal oxide fine particles being biased in the opposite direction to the ultraviolet irradiation. Further, this refractive index gradient changes depending on slight conditions of ultraviolet curing, so that the change is large. Therefore, the reproducibility of the high diffraction efficiency state in the entire visible range of the multilayer diffractive optical element is poor. In addition, it is observed that when the gradient is increased due to the deviation of the fine particles, the scattering is increased in some cases.

The present invention has been made in view of such a background art, and suppresses a refractive index gradient and light scattering due to movement of fine particles during curing of an energy curable resin composition while maintaining low refractive index and high dispersion characteristics. The present invention provides an energy curable resin composition and an optical material.
The present invention also provides a multilayer diffractive optical element using the energy curable resin composition.

A multilayer diffractive optical element that solves the above problems includes a first layer formed of a high refractive low dispersion material having a diffraction grating shape on at least one surface, and a low refraction having a diffraction grating shape on at least one surface. A multilayer diffractive optical element, wherein the second layer formed of a highly dispersed material is laminated so that the diffraction grating shapes thereof face each other,
The low refractive and high dispersion material of the second layer is obtained by energy curing an energy curable resin composition,
The energy curable resin composition comprises (A) one or more fluorine-based monomers having a polymerizable functional group in the molecule and one acrylic monomer having two or more polymerizable functional groups in the molecule. An energy curable resin composition comprising an organic component containing at least a seed, (B) transparent conductive metal oxide fine particles, and (C) a polymerization initiator, wherein (A) the organic component The content is 40 wt% or more and 68 wt% or less, and the content of the acrylic monomer contained in the organic component is 1.3 wt% or more and 5.0 wt% or less with respect to the organic component. It is characterized by being.

According to the present invention, an energy curable resin composition and an optical that can suppress a refractive index gradient and light scattering due to movement of fine particles during curing of the energy curable resin composition while maintaining low refractive index and high dispersion characteristics. Material can be provided.
In addition, the present invention can provide a multilayer diffractive optical element using the energy curable resin composition.

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 preparation methods of the sample for refractive index measurement. It is a schematic diagram which shows the preparation methods of the sample for a scattering rate measurement. It is a schematic diagram which shows the preparation methods of the sample for shape transferability evaluation. It is a schematic diagram which shows the preparation methods of the sample for evaluation of diffraction efficiency.

Hereinafter, the present invention will be described in detail.
The energy curable resin composition according to the present invention comprises (A) one or more fluorine-based monomers having a polymerizable functional group in the molecule and an acrylic monomer having two or more polymerizable functional groups in the molecule. An energy curable resin composition comprising an organic component containing at least one body, (B) transparent conductive metal oxide fine particles, and (C) a polymerization initiator, wherein (A) The content of the organic component is 40% by weight or more and 68% by weight or less, and the content of the acrylic monomer contained in the organic component is 1.3% by weight or more and 5.0% by weight with respect to the organic component. % Or less.

  The content of each component contained in the energy curable resin composition of the present invention is the content of each component contained in the energy curable resin composition having a residual solvent content of 0.1% by weight. Represents an amount.

  The energy curable resin composition of the present invention is used as a low-refractive-index high-dispersion material, suppresses uneven dispersion of transparent conductive metal oxide fine particles such as ITO, and has a refractive index gradient generated by uneven dispersion, Since an increase in scattering due to aggregation can be suppressed, it can be suitably used as an optical material.

The energy curable resin composition of the present invention contains (B) transparent conductive metal oxide fine particles.
Preferred examples of the transparent conductive metal oxide fine particles (hereinafter abbreviated as fine particles) used in the present invention include zinc oxide, indium oxide, tin oxide, antimony oxide, indium tin oxide (ITO), antimony. , Tin oxide doped with zinc (ATO), zinc doped indium oxide (IZO), aluminum doped zinc oxide (AZO), and fluorine doped tin oxide (FTO), preferably indium tin oxide It is preferable to use an object (ITO). This is because indium tin oxide (ITO) has the smallest secondary dispersion characteristic (θgF) among the existing materials and is the material that 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.

  The content of the transparent conductive metal oxide fine particles contained in the energy curable resin composition of the present invention is from 32% by weight to 68% by weight, and preferably from 39% by weight to 56% by weight. If it is 32 wt% or more and 68 wt% or less, the optical properties and moldability will be good.

It is also 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 of the organic component serving as the base resin and the fine particles are dispersed in advance.
The fine particles preferably have a particle size that does not adversely affect light transmittance, optical scattering, and the like, and preferably have an average particle size of 2 nm to 30 nm, particularly 2 nm to 20 nm. 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 filtering with a filter having relatively small pores than the particle size to be removed. The state to be removed is, for example, a state in which fine particles are dispersed in a solvent before mixing the base resin (fine particle dispersion), a state in which the base resin is dissolved in the fine particle dispersion, or depending on the viscosity. A state in which the solvent is removed in a state to make the base resin and fine particles solvent-free is preferable.

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.
Examples of suitable dispersion solvents for use in the present invention include toluene, benzene, or the like in order to dissolve organic components or to disperse fine particles in a solvent, and to dissolve surface treatment agents and dispersants as necessary. , Aromatic hydrocarbons such as xylene, 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, DMF, DMAc, NMP Amides such as hexane, octane and other aliphatic hydrocarbons, ethyl ethers such as diethyl ether and butyl carbitol, and halogenated hydrocarbons such as dichloromethane and carbon tetrachloride, but are not limited thereto. Absent. 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.

In addition, it is preferable that content of the solvent contained in the energy curable resin composition of this invention is 0.1 weight% or less.
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.

  The amount of the surface treatment agent and dispersant added is roughly divided into the surface treatment agent, the type of dispersant, the type of fine particles, the surface area (fine particle diameter) of the fine particles, the type of dispersion resin in which the fine particles are mixed, and the like. In the present invention, it is desirable to be in the range of 0.1% by weight to 25.0% by weight with respect to the weight of the fine particles. If the added amount of the dispersant is too large, it causes white turbidity and optical scattering occurs. Also, characteristics of the composition obtained by containing fine particles (refractive index, Abbe number, secondary dispersion characteristics, elastic modulus, etc.) ) Is unnecessarily reduced, and is preferably in the range of 4.0 wt% or more and 20.0 wt% or less. 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 energy curable resin composition of the present invention comprises (A) one or more fluorine-based monomers having a polymerizable functional group in the molecule and an acrylic monomer having two or more polymerizable functional groups in the molecule. Containing one or more organic components.

  The content of the organic component contained in the energy curable resin composition of the present invention is 40% by weight to 68% by weight, preferably 44% by weight to 61% by weight. If it is 40 weight% or more and 68 weight% or less, an optical characteristic and a moldability will become favorable.

As the fluorine-based monomer having a polymerizable functional group in the molecule, those that are compatible with a solvent, a surface treatment agent, a dispersing agent and the like in which transparent conductive metal oxide fine particles are dispersed are desirable.
Examples of fluorine monomers 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, 9H-hexadecafluorononoxy) -1,2-epoxypropane, 1,4-bis And monomers such as (2 ′, 3′-epoxypropyl) -perfluoro-n-butane, and the like.

  It is not particularly limited to any one of these monomers, and a polymer fluororesin may be selected. The copolymer is a commercial product manufactured by Central Glass Co., Ltd. 702C, 703C, 704C, 705C, 706C, 707C and the like.

  The said fluorine-type monomer can also be used only by 1 type, and can also be used in combination of 2 or more types.

  Next, examples of the acrylic monomer having two or more polymerization functional groups in the molecule include a solvent in which transparent conductive metal oxide fine particles are dispersed, and fluorine having a polymerization functional group in the molecule. Those that are compatible with the system monomer, surface treatment agent, and dispersant are desirable.

  The acrylic monomer is not particularly limited as long as it has two or more double bonds or triple bonds in the molecule, but the polymerization functional group is preferably (meth) acrylate. Specific examples of the monomer having two or more polymerization functional groups of (meth) acrylate include 1,4-divinylcyclohexane, 1,4-cyclohexanedimethanol divinyl ether, divinylbenzene, 1,6- Divinyl naphthalene, ethoxylated bisphenol A divinyl ether, acrylate or methacrylate of propoxylated bisphenol A divinyl ether; polyethylene glycol di (meth) acrylate, polypropylene di (meth) acrylate, trimethylolethane tri (meth) acrylate, neoventyl glycol di (Meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, hexanediol (Meth) acrylate, tricyclodecane dimethanol diacrylate, tri (acryloyloxyethyl) isocyanurate, acrylates or methacrylates of tris (2-acryloyloxyethyl) isocyanurate and the like to them.

Acrylic monomers can be used alone or in combination of two or more.
(A) As for content of the acryl-type monomer contained in an organic component, 1.3 to 5.0 weight% is desirable with respect to the said organic component. If it is less than 1.3% by weight, it is difficult to suppress the gradient of refractive index due to the movement of fine particles during energy curing. On the other hand, if it is larger than 5.0% by weight, the increase in the refractive index cannot be suppressed.

  It is desirable that the organic component is blended with other components and the dispersion solvent is removed, and then at least heated to form a melt. More preferably, it is a melt at room temperature in view of handling. If it becomes a melt at the time of heating due to solid properties such as crystallinity at room temperature, it needs to be cured while being heated at the time of molding, which causes problems in handling and molding accuracy. In addition, various selections should be made in terms of transparency, compatibility, dispersibility (stability), curability, moldability, durability, and the like.

In general, fluorine-based materials have low compatibility with general-purpose resins. For this reason, it is preferable that the mixture does not cause white turbidity or precipitation when it is mixed with the surface treatment agent or dispersant of fine particles or when the dispersion solvent is removed. This is because a decrease in compatibility greatly affects optical scattering and transmittance. In the present invention, an acrylic monomer having two or more polymerizable functional groups is added in order to suppress a refractive index gradient and light scattering due to movement of fine particles during energy curing. In that case,
It must be formulated with consideration for fluctuations in optical properties such as the refractive index of the cured product.

The energy curable resin composition of the present invention contains (C) a polymerization initiator.
In the present invention, as a photopolymerization initiator in the case of using a photopolymerizable resin for the organic component of the binder, it is preferable to use a radical generation mechanism by light irradiation using a radical polymerization initiator. Usually, it is preferable for replica molding of lenses and the like.

  Examples of the photopolymerization initiator that can be used for the organic component include 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 1-hydroxy-cyclohexyl-phenylketone, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 4-phenylbenzophenone, 4-phenoxybenzophenone, Preferred examples include 4,4′-diphenylbenzophenone and 4,4′-diphenoxybenzophenone. In addition, the addition ratio of the photopolymerization initiator with respect to the organic component can be appropriately selected according to the amount of light irradiation, and further according to the additional heating temperature, and also according to the target average molecular weight of the obtained polymer. Can also be prepared.

  When used for curing / molding the resin according to the present invention, the amount of photopolymerization initiator added is 0.01% by weight based on the organic 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 wt% or less, preferably 0.50 wt% or more and 5.00 wt% or less. The photopolymerization initiator can be used alone or in combination of two or more depending on the reactivity with the organic component and the wavelength of light irradiation.

The optical material of the present invention is an optical material composed of the energy curable resin composition described above.
Next, the process for preparing the optical material of the present invention will be described. The case where the energy curable resin composition using the photopolymerizable organic component is used as the example is demonstrated.

  First, an appropriate amount of a surface treatment agent or dispersant is dissolved in a solvent, fine particles are added, shear force is applied, fine particle aggregates are crushed, and the remaining aggregates are removed by centrifugation and filter treatment to obtain a uniform fine particle dispersion. obtain. Thereafter, the photopolymerizable organic component and the photopolymerization initiator are dissolved. In order to dissolve the organic component in the fine particle dispersion, it is desirable to use a combination of a solvent, a surface treatment agent, and a dispersant that are unlikely to deteriorate the dispersion state of the fine particles due to the addition of the organic 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. Rapid evaporation and removal of the solvent may deteriorate the degree of aggregation of the fine particles and impair the 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 can be obtained.

  The obtained optical material may contain a residual solvent that cannot be completely removed. If the content is larger than 0.1% by weight, the refractive index gradient (GI) and light scattering become large in order to promote the movement of fine particles during energy curing. Therefore, the content of residual solvent is desirably 0.1% by weight or less.

  However, if the degree of vacuum is too high, or accompanied by heating at the same time as the vacuum, or through a vacuum process for a long time, monomers such as surface treatment agents, dispersants and organic components 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.

The optical material of the present invention is cured by irradiation with ultraviolet rays and visible light as energy, the refractive index (nd) of the cured optical material is 1.32 or more and 1.53 or less, and the Abbe number is 14 or more and 35 or less. And the secondary dispersion characteristic (θgF) is preferably 0.34 or more and 0.47 or less.

  Next, the multilayer diffractive optical element of the present invention includes a first layer made of a highly refractive low dispersion material having a diffraction grating shape on at least one surface, and a diffraction grating shape on at least one surface. And a second layer made of a low-refractive high-dispersion material having layers such that the diffraction grating shapes are opposed to each other, and the low-refractive high-dispersion material of the second layer is made of the above-mentioned energy curable resin composition. It is characterized by becoming.

  The first layer is made of an organic resin containing inorganic fine particles containing zirconium oxide, and the organic resin is tris (2-acryloxyethyl) isocyanurate, pentaerythritol triacrylate, dicyclopentenyloxyethyl methacrylate, It is preferably obtained by ultraviolet curing a mixture of urethane-modified polyester acrylate and 1-hydroxycyclohexyl phenyl ketone.

The content of the inorganic fine particles containing zirconium oxide contained in the first layer is preferably 15.9 wt% or more and 24.0 wt% or less.
The scattering rate of the multilayer diffractive optical element is preferably 1.0% or less.

  It is preferable that the grating height of the multilayer diffraction grating is 8 μm or more and 15 μm or less, and the diffraction efficiency of the designed order is 98% or more in the visible light region having a wavelength of 400 nm or more and 700 nm or less.

  In the molding of a multilayer diffractive optical element according to the present invention, a process of forming a mold body layer from the energy curable resin composition using a photopolymerization method is shown. A thin layer structure is formed on a transparent substrate. For example, a mold is performed by pouring an optical material exhibiting fluidity between a glass flat plate of a substrate and a metal material mold corresponding to a fine diffraction grating structure and suppressing it lightly. While maintaining this state, photopolymerization of the optical material is performed. 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, light is uniformly irradiated to the molded optical material through the transparent substrate. 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.

  In addition, instead of metal materials in the mold corresponding to the fine diffraction grating structure, other materials of the multilayer diffractive optical element, specifically, a relatively high refractive index and low dispersion material are formed into a fine diffraction grating structure. You may use what you did.

  1A and 1B are schematic views showing an embodiment of the multilayer diffractive optical element of the present invention. FIG. 1A is a plan view and FIG. 1B is a cross-sectional view taken along line AA. Reference numeral 100 denotes a laminated diffractive optical element, 1 denotes a high refractive low dispersion layer made of a high refractive low dispersion material, 2 denotes a low refractive high dispersion layer made of a low refractive high dispersion material, and 3 denotes a transparent substrate. The multilayer diffractive optical element is provided with the low refractive and high dispersion layer 2 of the second layer in contact with the surface of the transparent substrate 3, and the high refractive and low dispersion layer 1 is laminated on the low refractive and high dispersion layer 2. ing.

When the energy curable resin composition is cured by irradiation with ultraviolet light or short-wavelength visible light, as shown in FIG. 1, the conductive fine particles have absorption in the ultraviolet region, and fluorine-based single particles. Compared to normal (meth) acrylate, the monomer is less reactive, increasing the non-uniformity of curing in the film thickness direction when curing the energy curable resin composition by ultraviolet light or short wavelength visible light, Refractive index gradient and light scattering are likely to occur due to movement of fine particles in the film thickness direction. In the present invention, by using an acrylic monomer having two or more polymerizable functional groups in the molecule, it is possible to prevent fine particle movement in the film thickness direction and reduce the occurrence of refractive index gradient and light scattering. .

  By utilizing the above method using the optical material in the present invention, a plurality of layers made of materials having different refractive index wavelength dispersions are laminated on the substrate, and the diffraction efficiency of a specific order (design order) is increased over the entire wavelength range to be used. A diffractive optical element designed as described above can be manufactured in a short time.

The preparation of the optical material in the present invention will be specifically described below.
Example 1
(Adjustment of low refractive index and high dispersion material)
First, Disper Big 163 (manufactured by Big Chemie) as a dispersant and ITO fine particles having an average particle diameter of 20 nm were mixed with xylene, the aggregate was crushed with a ball mill, and then the aggregate was removed by centrifugation. 1 μm filter treatment was performed. As a result, an ITO fine particle dispersion (X) in a xylene solvent was obtained. In the obtained ITO fine particle dispersion (X), the content of ITO fine particles was 9.90% by weight, and the content of dispersant was 1.20% by weight.

[Adjustment of optical material 11]
1.67 g of 3-perfluorobutyl-2-hydroxypropyl acrylate as an organic component, 2,2,3,3,4,4,5,5-octa as an organic component with respect to 47.33 g of the above ITO fine particle dispersion (X) 2.50 g of fluorohexane 1,6-diacrylate and 0.155 g of tris (2-acryloxyethyl) isocyanurate were added and dissolved. Further, 0.130 g of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) was added as a photopolymerization initiator and dissolved. The obtained solution was depressurized with an evaporator, and finally the solvent was removed under the conditions of an oil bath temperature of 45 ° C. and a set atmospheric pressure of 3 hPas for 40 hours to prepare an optical material 11. The ratio of tris (2-acryloxyethyl) isocyanurate, which is an acrylic monomer having two or more polymerizable functional groups, in the curable resin composition was 2.9% by weight.

Moreover, the optical material 11 was baked by TGA (manufactured by Perkin Elmer), and the amount of inorganic solid content in the optical material 11 was quantified. As a result, it was 46.7% by weight.
The content of the residual solvent (xylene) was 0.0025% by weight as a result of measurement by gas chromatography (5890 series II: manufactured by Hewlett Packard).

[Adjustment of optical material 12]
1.67 g, 2,2,3,3,4,4,5,5-5-perfluorobutyl-2-hydroxypropyl acrylate as an organic component with respect to 46.33 g of the above ITO fine particle dispersion (X) slurry 2.50 g of octafluorohexane 1,6-diacrylate and 0.155 g of tris (2-acryloxyethyl) isocyanurate were added and dissolved. Further, 0.130 g of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) was added as a photopolymerization initiator and dissolved. The obtained solution was depressurized with an evaporator, and finally the solvent was removed under the conditions of an oil bath temperature of 45 ° C. and a set pressure of 3 hPas for 40 hours to prepare an optical material 12. The proportion of tris (2-acryloxyethyl) isocyanurate, which is an acrylic monomer having two or more polymerizable functional groups, in the organic substance was 2.9% by weight.

Moreover, the optical material 12 was baked by TGA (manufactured by PerkinElmer), and the amount of inorganic solid content in the optical material 12 was quantified. As a result, it was 46.2% by weight.
The content of the residual solvent (xylene) was measured by gas chromatography (5890 series II: manufactured by Hewlett Packard). As a result, 0.0022% by weight
Met.

[Adjustment of optical material 13]
1.67 g, 2,2,3,3,4,4,5,5-5-perfluorobutyl-2-hydroxypropyl acrylate as an organic component with respect to 48.67 g of the above ITO fine particle dispersion (X) slurry 2.50 g of octafluorohexane 1,6-diacrylate and 0.155 g of tris (2-acryloxyethyl) isocyanurate were added and dissolved. Further, 0.130 g of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) was added as a photopolymerization initiator and dissolved. The solvent was depressurized from the solution obtained by the evaporator and finally removed under the conditions of an oil bath temperature of 45 ° C. and a set atmospheric pressure of 3 hPas for 40 hours to prepare an optical material 13. The proportion of tris (2-acryloxyethyl) isocyanurate, which is an acrylic monomer having two or more polymerizable functional groups, in the organic substance was 2.9% by weight.

Moreover, the optical material 13 was baked by TGA (manufactured by PerkinElmer), and the amount of inorganic solid content in the optical material 13 was quantified. As a result, it was 47.1% by weight.
The content of the residual solvent (xylene) was 0.0022% by weight as a result of measurement by gas chromatography (5890 series II: manufactured by Hewlett Packard).

(Evaluation of optical properties)
The optical properties of the optical materials 11 to 13 were evaluated as follows.

<Refractive index>
The refractive index of each optical element was measured by preparing a sample as follows.
First, as shown in FIG. 2, a spacer 7 and a measurement material 5 (optical materials 11 to 13) having a thickness of 12.5 μm are placed on a high-refractive glass (S-TIH11: made by Hoya) 4 having a thickness of 1 mm. Arranged. A high-refractive index glass (S-TIH11: manufactured by Hoya) 6 having a thickness of 1 mm was placed thereon via a spacer 7, and the measurement material 5 was spread and used as a sample.

This sample was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under conditions of 2900 seconds (20.3 J) at 7 mW / cm ² (illuminance through S-TIH11), and the sample was cured. The cured sample was measured using a refractometer (KPR-30, Shimadzu Corporation) from the high refractive index glass 4 side, g line 435.8 nm, f line 486.1 nm, e line 546.1 nm, d line. The refractive index of each wavelength of 587.6 nm and c-line 656.3 nm was measured.

In addition, an optical constant (ν _d , θ _gF ) was calculated from the measured refractive index.
The optical constant is defined as follows.
ν _d = (n _d −1) / (n _F −n _C ), θ _gF = (n _g −n _F ) / (n _F −n _C )
The optical materials 11 to 13 have a refractive index (nd) of 1.32 to 1.53, an Abbe number of 14 to 35, and a secondary dispersion characteristic (θgF) of 0.34 to 0.47. It was.

Moreover, the refractive index of d-line 587.6nm was measured from the high refractive index glass 8 (S-TIH11 [made by OHARA)] side, and the refractive index gradient was defined from the refractive index difference from the high refractive index glass 4 side.
Similarly, a sample with an irradiation intensity of 14 mW / cm 2 (illuminance through S-TIH 11) and a condition of 1450 seconds (20.3 J) was also prepared, and the refractive index of d-line 587.6 nm on the high refractive index glass 6 side. The measurement was defined as irradiation sensitivity based on the difference in refractive index of the sample prepared at 7 mW / cm ² .

<Scattering rate>
The transmittance of each optical element was measured by preparing a sample as follows.
First, as shown in FIG. 3, a spacer 7 having a thickness of 12.5 μm and a measurement material 5 (optical materials 11 to 13) were arranged on a glass substrate 8 having a thickness of 1 mm. A glass substrate 8 having a thickness of 1 mm was placed thereon, and the measurement material 5 was spread and used as a sample. This sample was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under conditions of 7 mW / cm ² and 2900 seconds, and the sample was cured. The cured sample was allowed to pass through transmitted light by removing the back of the integrating sphere of the spectrophotometer (U4000, Hitachi) with a spectrophotometer (U4000, Hitachi, Ltd.), and the other scattered light was measured.

<Confirmation of fine particle concentration difference>
The sample glass used for the refractive index measurement was removed, and the high refractive index glass 8 (irradiation surface) side and the high refractive index glass 4 (back surface) side were measured with XPS (Quantera SXM: ULVAC, Inc.), respectively. The existence ratio of was compared.

The measurement results of the optical materials 11 to 13 are shown below.
(1) Result refractive index of the optical material _{11 (n g, n F,} n e, n d, n C) = (1.532,1.520,1.510,1.503,1.492)
(Ν _d , θ _gF ) = (17.8, 0.39)
Refractive index gradient Δnd = 1.503 (high refractive index glass 8 side) −1.500 (high refractive index glass 6 side) = 0.003
Irradiation sensitivity Δnd (irradiation intensity difference) = 1.503 (7 mW / cm ² ) −1.501 (14 mW / cm ² ) = 0.002
Scattering rate 0.3%
Difference in concentration of fine particles ΔIn = 16 atomic percent (high refractive index glass 8 side) −13 atomic percent (high refractive index glass 6 side) = 3 atomic percent

(2) Results refractive index of the optical material _{12 (n g, n F,} n e, n d, n C) = (1.530,1.519,1.508,1.502,1.491)
(Ν _d , θ _gF ) = (17.9, 0.40)
Refractive index gradient Δnd = 1.502 (high refractive index glass 8 side) −1.499 (high refractive index glass 6 side) = 0.003
Irradiation sensitivity Δnd (irradiation intensity difference) = 1.502 (7 mW / cm ² ) −1.500 (14 mW / cm ² ) = 0.002
Scattering rate 0.3%
Difference in concentration of fine particles ΔIn = 16 atomic percent (high refractive index glass 8 side) −13 atomic percent (high refractive index glass 6 side) = 3 atomic percent

(3) Results refractive index of the optical material _{13 (n g, n F,} n e, n d, n C) = (1.533,1.522,1.511,1.504,1.493)
(Ν _d , θ _gF ) = (17.6, 0.39)
Refractive index gradient Δnd = 1.504 (high refractive index glass 8 side) −1.501 (high refractive index glass 6 side) = 0.003
Irradiation sensitivity Δnd (irradiation intensity difference) = 1.504 (7 mW / cm ² ) −1.502 (14 mW / cm ² ) = 0.002
Scattering rate 0.3%
Difference in concentration of fine particles ΔIn = 16 atomic percent (high refractive index glass 8 side) −13 atomic percent (high refractive index glass 6 side) = 3 atomic percent

Comparative Example 1
Unlike the examples, the proportion of tris (2-acryloxyethyl) isocyanurate, which is an acrylic monomer having two or more polymerizable functional groups in the molecule, in the organic substance is 0% by weight and 0.8% by weight. An optical material 20 and an optical material 21 were prepared and their characteristics were measured.

[Adjustment of optical material 20]
1.67 g of 3-perfluorobutyl-2-hydroxypropyl acrylate as an organic component, 2,2,3,3,4,4,5,5-octa as an organic component to 45.83 g of the ITO fine particle dispersion (X) 2.50 g of fluorohexane 1,6-diacrylate was added and dissolved. Further, 0.130 g of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) was added as a photopolymerization initiator and dissolved. The obtained solution was depressurized with an evaporator, and finally the solvent was removed under the conditions of an oil bath temperature of 45 ° C. and a set pressure of 3 hPas for 40 hours to prepare an optical material 20. In this comparative example, an acrylic monomer having two or more polymerization functional groups is not contained in the organic substance.

Moreover, the optical material 20 was baked by TGA (manufactured by Perkin Elmer), and the amount of inorganic solid content in the optical material 20 was quantified. As a result, it was 46.7% by weight.
The content of the residual solvent (xylene) was 0.0020% by weight as a result of measurement by gas chromatography (5890 series II: manufactured by Hewlett Packard).

[Adjustment of optical material 21]
1.67 g of 3-perfluorobutyl-2-hydroxypropyl acrylate as an organic component, 2,2,3,3,4,4,5,5-octa as an organic component with respect to 46.00 g of the ITO fine particle dispersion (X) 2.50 g of fluorohexane 1,6-diacrylate and 0.042 g of tris (2-acryloxyethyl) isocyanurate were added and dissolved. Further, 0.130 g of 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) was added and dissolved as a photopolymerization initiator. The obtained solution was depressurized with an evaporator, and finally the solvent was removed under the conditions of an oil bath temperature of 45 ° C. and a set atmospheric pressure of 3 hPas for 40 hours to prepare an optical material 21. The proportion of tris (2-acryloxyethyl) isocyanurate, which is an acrylic monomer having two or more polymerizable functional groups, in the organic substance was 0.8% by weight.

Moreover, the optical material 21 was baked by TGA (manufactured by Perkin Elmer), and the amount of inorganic solid content in the optical material 11 was quantified. As a result, it was 46.6% by weight.
The content of the residual solvent (xylene) was 0.0021% by weight as a result of measurement by gas chromatography (5890 series II: Hewlett Packard).

The measurement results of the optical materials 20 and 21 are shown below.
(1) Resulting refractive index (n _g , n _F , n _e , n _d , n _C ) = (1.532, 1.521, 1.510, 1.503, 1.492) of the optical material 20
(Ν _d , θ _gF ) = (17.5, 0.39)
Refractive index gradient Δnd = 1.503 (refractive index glass 8 side) −1.495 (high refractive index glass 6 side) = 0.008
Irradiation sensitivity Δnd (irradiation intensity difference) = 1.503 (7 mW / cm ² ) −1.497 (14 mW / cm ² ) = 0.006
Scattering rate 0.5%
Difference in concentration of fine particles ΔIn = 17 atomic percent (high refractive index glass 8 side) −11 atomic percent (high refractive index glass 6 side) = 6 atomic percent

(2) Results refractive index of the optical material _{21 (n g, n F,} n e, n d, n C) = (1.532,1.521,1.510,1.503,1.492)
(Ν _d , θ _gF ) = (17.6, 0.39)
Refractive index gradient Δnd = 1.503 (refractive index glass 8 side) −1.498 (high refractive index glass 6 side) = 0.005
Irradiation sensitivity Δnd (irradiation intensity difference) = 1.503 (7 mW / cm ² ) −1.499 (14 mW / cm ² ) = 0.004
Scattering rate 0.4%
Difference in concentration of fine particles ΔIn = 16 atomic percent (high refractive index glass 8 side) −12 atomic percent (high refractive index glass 6 side) = 4 atomic percent As described above, an acrylic system having two or more polymerization functional groups in the molecule In the absence of monomer, it can be seen that the refractive index gradient, illuminance sensitivity and material scattering are large.

Example 2
The Example of a multilayer diffractive optical element is shown.
Next, a diffractive optical shape was formed with the optical material materials 11 to 31, and a multilayered diffractive optical element was prepared by laminating the high refractive index and low dispersion material A1 without making a space, and evaluated.

<Adjustment of high refractive index and low dispersion material A1>
<Preparation of high refractive and low dispersion material>
First, 69.10 g of a fine particle dispersion (average particle size of 3 nm, zirconia concentration of 10.08 wt%, surface treatment agent concentration of 3.74 wt%) dispersed in a toluene solvent as an ultraviolet curable acrylic resin is tris. (2-acryloxyethyl) isocyanurate 20.3% by weight, 25.3% by weight of pentaerythritol triacrylate, 39.2% by weight of dicyclopentenyloxyethyl methacrylate, 12.7% by weight of urethane-modified polyester acrylate, 20.64 g of a mixture of 2.5% by weight of hydroxycyclohexyl phenyl ketone was mixed. This mixed solution was put into an evaporator, and finally the toluene solvent was removed at an oil bath temperature of 45 ° C., a set atmospheric pressure of 3 hPas for 15 hours, and a high refractive index and low dispersion material A1 was prepared. The measurement was performed with a laser particle size distribution meter (ELS: Otsuka Electronics).

Further, the high refractive index and low dispersion material A1 was baked by TGA (manufactured by Perkin Elmer), and the amount of inorganic solid content in the high refractive index and low dispersion material A1 was quantified. As a result, it was 23.1% by weight.
The content of the residual solvent (xylene) was 0.015% by weight as a result of measurement by gas chromatography (5890 series II: manufactured by Hewlett Packard).

<Results of High Refractive Index Low Dispersion Material A1>
Evaluation similar to that of the optical material was performed. However, the refractive index spacer 7 with 30μm of 12.5μm sample for measurement for refractive index measurement sample and the transmittance _{(n g, n F, n} e, n d, n C) = (1.566,1 .560, 1.555, 1.552, 1.549)
(Ν _d , θ _gF ) = (49.1, 0.58)
Refractive index gradient Δnd = 1.552 (high refractive index glass 8 side) −1.552 (high refractive index glass 6 side) = 0.000
Irradiation sensitivity Δnd (irradiation intensity difference) = 1.552 (7 mW / cm ² ) −1.552 (14 mW / cm ² ) = 0.000
Scattering rate 0.1% (30μm thickness)

<Creation of multilayer diffraction grating>
As shown in FIG. 4, an optical material sample 5 (optical materials 11 to 21) was placed on a diffraction grating-shaped mold 9, and a 2 mm thick flat glass 10 was placed thereon. High pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) was irradiated under conditions of 7 mW / cm ² , 2900 seconds and 14 mW / cm ² , 1450 seconds, and annealed at 80 ° C. for 72 hours for diffraction. A grid was created.

The grating height measured after annealing was 11.2 μm, and the pitch was 80 μm.
Table 1 below shows the configuration of the diffraction grating.

Next, as shown in FIG. 5, the optical material sample 5 molded on the flat glass 10 is set together with the flat glass 10 on a forming jig 12, and then the optical material sample 13 (high refractive index) is formed on the optical material sample 5. The low-dispersion material A1) was dropped (FIG. 5 (a)). A flat glass 10 was placed thereon, and a sample was spread out so that the thickness of the resin was 20 μm higher than the height of the lattice. (FIG. 5B). This sample was irradiated with a high-pressure mercury lamp (EXECURE250, HOYA CANDEO OPTRONICS Co., Ltd.) under the conditions of 7 mW / cm ² and 2900 seconds, and after the sample was cured, it was annealed at 80 ° C. for 72 hours to obtain a multilayer diffractive optical element. Created.
Table 2 below shows the configuration of the multilayer diffractive optical element.

<Evaluation of diffraction efficiency>
Diffraction efficiency is a transmittance ratio when a member on a substrate made of the same resin as the diffractive optical element and having the same film thickness is irradiated with a light amount of the designed order of the diffraction grating. The same film thickness as the diffractive optical element is an average film thickness of the diffractive optical element.

<Measurement of flare rate>
The flare rate of each multilayer diffractive optical element was measured as follows.
Incident light is incident on the multilayer diffractive optical element and the back of the integrating sphere of the spectrophotometer (U4000, Hitachi, Ltd.) is removed, allowing the diffracted light of the designed order to pass through and measuring flare light other than that. did.

Multilayer diffractive optical elements 11-1 to 13-2 made of optical materials 11 to 13 have a diffraction efficiency of 98% or more in the entire visible range, and the influence of irradiation conditions during element molding is small.
On the other hand, multilayer diffractive optical elements 20-1 to 21-2 made from optical materials 20 and 21 in which an acrylic monomer having two or more polymerizable functional groups in the molecule is 1.3% by weight or less are: The diffraction efficiencies of the multilayer diffractive optical elements 20-1 and 21-1 are 98% or more in the entire visible range. However, in the multilayer diffractive optical elements 20-2 and 21-2 having different irradiation conditions, the diffraction efficiency is less than 98% in a part of visible, and the influence of the irradiation conditions for element molding is large.

  The optical material comprising the energy curable resin composition of the present invention can exhibit characteristics of low refractive index and high dispersion and low refractive index secondary dispersion while controlling the gradient of fine particles during curing. 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 High refraction low dispersion layer 2 Low refraction high dispersion layer 3 Transparent substrate 4 High refraction glass (back side)
5 Optical material sample 6 High refractive glass (irradiation side)
7 Spacer 8 Glass substrate 9 Mold 10 Flat glass 11 Mold release jig 12 Molding jig 13 Optical material sample 100 Multilayer diffractive optical element

Claims (11)

A first layer formed of a high refractive low dispersion material having a diffraction grating shape on at least one surface, and a second layer formed of a low refractive high dispersion material having a diffraction grating shape on at least one surface Are multilayer diffractive optical elements laminated so that their diffraction grating shapes face each other,
The low refractive and high dispersion material of the second layer is obtained by energy curing an energy curable resin composition,
The energy curable resin composition comprises (A) one or more fluorine-based monomers having a polymerizable functional group in the molecule and one acrylic monomer having two or more polymerizable functional groups in the molecule. An energy curable resin composition comprising an organic component containing at least a seed, (B) transparent conductive metal oxide fine particles, and (C) a polymerization initiator, wherein (A) the organic component The content is 40 wt% or more and 68 wt% or less, and the content of the acrylic monomer contained in the organic component is 1.3 wt% or more and 5.0 wt% or less with respect to the organic component. There is a multilayer diffractive optical element.   The fluorine-based monomer contained in the organic component (A) is 3-perfluorobutyl-2-hydroxypropyl acrylate or 2,2,3,3,4,4,5,5-octafluorohexane 1, The multilayer diffractive optical element according to claim 1, wherein the multilayer diffractive optical element is 6-diacrylate, and the acrylic monomer is tris (2-acryloxyethyl) isocyanurate.   The multilayer diffractive optical element according to claim 1, wherein the polymerization initiator is 1-hydroxycyclohexyl phenyl ketone.   The multilayer diffractive optical element according to claim 1, wherein the transparent conductive metal oxide fine particles are indium tin oxide (ITO).   5. The multilayer diffractive optical element according to claim 1, wherein the content of the solvent contained in the energy curable resin composition is 0.1% by weight or less. The low refractive index and high dispersion material of the second layer, the refractive index (nd) is 1.32 or more 1.53 or less, at up base number 14 to 35 or less, second-order dispersion characteristic (? GF) is 0 The multilayer diffractive optical element according to claim 1, wherein the multilayer diffractive optical element is .34 or more and 0.47 or less. On the surface of the transparency substrate, the multilayer diffractive optical element according to any one of claims 1 to 6, characterized in that provided in contact said second layer.   The first layer is an organic resin containing inorganic fine particles containing zirconium oxide, and the organic resin is tris (2-acryloxyethyl) isocyanurate, pentaerythritol triacrylate, dicyclopentenyloxyethyl methacrylate, The multilayer diffractive optical element according to any one of claims 1 to 7, wherein the multilayer diffractive optical element is obtained by ultraviolet curing a mixture of urethane-modified polyester acrylate and 1-hydroxycyclohexyl phenyl ketone.   The multilayer diffractive optical element according to claim 8, wherein the content of the inorganic fine particles containing zirconium oxide contained in the first layer is 15.9 wt% or more and 24.0 wt% or less. .   The multilayer diffractive optical element according to claim 1, wherein a scattering rate of the multilayer diffractive optical element is 1.0% or less. It said multilayer height of the grating of the diffraction grating is at 15μm or less than 8 micron m, claims 1 to 10 in the following visible light range 700nm or more wavelength 400 nm, the diffraction efficiency of the designed order is equal to or greater than 98% The multilayer diffractive optical element according to any one of the above.

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