Abstract: The invention relates to applying novel photo polymers based on special urethane acrylates as writing monomers in printing methods which are suitable for producing holographic media, in particular for the visual display of images.

Abstract: The invention relates to a method for producing novel photopolymers on the basis of prepolymer-based polyurethane compositions that are suitable for producing holographic media, in particular for the visual display of images.

Abstract: Technologies are generally described for reproducing holographic images by causing a photo-induced change in the diffractive index of a holographic recording medium. An example device may include a light irradiation unit and a transparent substrate. The light irradiation unit can be configured to transmit a photo-inducing light. Further, the transparent substrate may have a predetermined refractive index and can be configured to include a first surface and a second surface opposite the first surface. The first surface can be configured to receive an incident light, and the second surface can be configured to receive the photo-inducing light. The transparent substrate can be configured to form interference fringe patterns from a photo-induced change in the refractive index of the transparent substrate responsive to the photo-induced light.

Abstract: Optical data storage media for bit-wise recording of a microhologram using an incident radiation at a wavelength of about 405 nm are provided. The optical storage medium includes (a) a non-photopolymer polymer matrix; (b) a non-linear sensitizer comprising a phenylethynyl platinum complex, wherein the non-linear sensitizer is capable of triplet-triplet energy transfer from an upper triplet state (Tn) of the non-linear sensitizer to a lower triplet state (T1) of a reactant, wherein “n” is an integer greater than 1; and (c) a reactant capable of undergoing a chemical change upon the triplet-triplet energy transfer from the non-linear sensitizer, thereby causing a refractive index change in the medium to record the microhologram.

Abstract: A method of producing a volume hologram laminate which can regenerate a hologram image in an arbitrary wavelength by a simple process. The method uses a volume hologram forming substrate which includes: a substrate, a volume hologram layer formed on the substrate and containing a photopolymerizable material, a resin layer, formed on the substrate so as to contact to the volume hologram layer, containing a resin and a polymerizable compound. The producing method includes processes of: a hologram recording process to record a volume hologram to the volume hologram layer, a substance transit process of transiting the polymerizable compound to the volume hologram layer, and an after-treatment process of polymerizing the polymerizable compound.

Abstract: The present invention relates to a novel holographic photopolymer based on prepolymer-based polyurethane compositions, the preparation of said photopolymer and its use for a very wide range of optical applications.

Abstract: Articles for recording a hologram are described. The articles include a holographic recording medium having a transparent polymeric binder and a photoreactive dye dispersed therein. The articles also include a first compound, dispersed in the holographic recording medium or disposed over a first surface of the holographic recording medium from which surface the hologram is viewed, that is transparent to light in the wavelength range to which the photoreactive dye is sensitive and which is capable of being converted to a converted compound that is opaque to light in the wavelength range to which the photoreactive dye is sensitive and transparent to light in a different wavelength range for viewing the hologram.

Abstract: Dynamic range enhancing dopants for photopolymeric media are described. Also described are optical articles using these dopants and methods for making such optical articles.

Abstract: A polymer composite prepared by melt blending, comprising an amorphous polymer; and a crystallizable polymer; wherein upon cooling the polymer composite, the amorphous polymer forms a continuous phase and the crystallizable polymer forms a dispersed phase, and wherein the dispersed phase is less than 200 nanometers in size.

Abstract: A component includes a micro-hologram layer, where the micro-hologram layer includes layers inert to light interleaved with layers of functional film. The functional film layers are made of a material that undergoes a change in its refractive index when illuminated by a light beam, yet undergoes no change in its refractive index when illuminated by a different light beam. The components may further include interleaved spacer films with multiple micro-hologram layers and other elements (e.g., servo layer, coatings, and the like) so as to comprise a data storage device. Methods of manufacturing the component and device are also disclosed.

Abstract: The present invention provides systems of recording holograms that reduce the writing time, increase the diffraction efficiency, improve the resolution, or restitute color. These systems are well suited for use with an updateable 3D holographic display using integral holography and photorefractive polymer.

Abstract: A major object of the present invention is to provide a volume hologram transfer foil that gives a volume hologram laminate higher in antiforgery function. The present invention achieves the object by providing a volume hologram transfer foil comprising: a substrate, a volume hologram layer carrying a recorded volume hologram that is formed on the substrate, and an image forming layer carrying a formed image and a heat seal layer containing a thermoplastic resin that are formed on the volume hologram layer, and comprising no reflective layer having a function to reflect light.

Abstract: According to one embodiment, a data reproducing apparatus includes a data recording medium, light source unit, light application unit, photodetector unit and control unit. An address mark string including address marks is formed on the data recording medium. The address marks are spaced from each other by a distance depending on address data. The light application unit is configured to split the light beam into a first branch light beam and a second branch light beam and apply the first and second branch light beams to the address mark string at different angles. The photodetector unit is configured to detect first reflected light beams and second reflected light beams from the address mark string to generate image data. The first and second reflected light beams result from the first and second branch light beams, respectively. The control unit is configured to reproduce address data based on the image data.

Abstract: The present invention provides a hologram recording material and a hologram recording medium, which are suitable for volume hologram record and can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, that is, storage stability, durability, low dimensional change (low shrinkage) and high multiplicity in holographic memory recording using not only a green laser but also a blue laser. A hologram recording material comprising: a radical photopolymerizable compound; and a matrix which is a dispersion medium for the radical photopolymerizable compound, wherein the radical photopolymerizable compound comprises a (meth)acrylamide derivative represented by the following general formula (I): CH2?CR1—CONR2—CH2—O—R3 (I) wherein R1 represents H or a CH3 group, R2 represents H or an organic group, and R3 represents an organic group having 3 or more carbon atoms in total. A hologram recording medium 11 which has a hologram recording layer 21.

Abstract: A method of manufacturing an article for display of a holographic image is described that includes thermally fusing a holographic recording medium containing a photochemically active dye dispersed in a transparent thermoplastic polymer binder to another layer or material; and then exposing the holographic film to intersecting beams of coherent light to form a holographic image therein formed by photoreacted areas of the photochemically active dye and unreacted areas of the photochemically active dye.

Abstract: A high speed hologram recording apparatus and method. The hologram recording apparatus includes: a light source for emitting coherent light; a beam splitter for splitting the coherent light emitted from the light source into a signal beam and a reference beam; a signal beam transfer unit comprising an angular deflector that changes a direction of the signal beam according to time, and irradiating the signal beam onto a hologram recording medium; and a reference beam transfer unit irradiating the reference beam at a location of the hologram recording medium where the signal beam is also irradiated.

Abstract: Producing complicated effects based on image processing operations. The image processing operations are defined for a processor which may be different than the processor which is actually used. The processor that is actually used runs an interpreter that interprets the information into its own language, and then runs the image processing. The actual information is formed according to a plurality of layers which are combined in some way so that each layer can effect the layers below it. Layers may add to, subtract from, or form transparency to the layer below it or make color filtering the layer below it. This enables many different effects computed and precompiled for a hypothetical processor, and a different processor can be used to combine and render those effects.

Abstract: The present invention provides a hologram recording material and a hologram recording medium that can stably maintain the shape of a recording layer and achieve high diffraction efficiency. A hologram recording material comprising a photoradical polymerizable compound (A), a photopolymerization initiator (B), and a dispersion medium (C). The medium (C) is selected from the group consisting of: a compound of the formula (I): wherein R11 is a divalent C2-4 hydrocarbon group, R12 and R13 each independently represent a C1-10 hydrocarbon group, k, l, m and n are each independently a number of 0 or more and 5 or less; and a compound of the formula (II): wherein R21 represents a divalent C1-6 hydrocarbon group, R22 and R23 each independently represent a C1-12 hydrocarbon group, and at least one of R22 and R23 represents a C5-12 hydrocarbon group.

Abstract: Disclosed herein is a hologram recording medium, wherein in a volume hologram, the hologram recording medium is covered with a partially patterned optical functional film on the side closer to the viewer than a hologram recording layer without the medium of air, and wherein the hologram recording medium maintains its appearance approximately unchanged irrespective of the presence or absence of the optical functional film.

Abstract: A method for identifying a blur profile of a multi image display with a first image separating mask. The method comprises displaying a calibration pattern through a second image separating mask, allowing an evaluator to provide a visual estimation indicating a blur brought about to the calibration pattern by the second image separating mask, and generating a blur profile of at least the first image separating mask according to the visual estimation. The first and second image separating masks having a substantially similar optical profile.

Abstract: There are provided compositions, optical data storage media and methods of using the optical data storage media. The compositions comprise a non-linear sensitizer comprising one or more subphthalocyanine reverse saturable absorbers capable of absorbing actinic radiation to cause upper triplet energy transfer to a reactant that undergoes a photochemical change upon triplet excitation.

Abstract: The invention concerns a security element in the form of a multi-layer film body having a volume hologram layer with two different items of optical information and a process for the production of such a security element.

Abstract: Methods for storing holographic data are presented. The method includes providing an optically transparent substrate comprising a thermally active photochemically active polymer composition, the polymer composition including a photochemically active dye and a heat generating chromophore, thermally activating at least a part of a volume element of the optically transparent substrate to increase a quantum efficiency of photochemical conversion of the photochemically active dye into a photo-product, within the at least a part of the volume element and converting at least some of the photochemically active dye to a photo-product, and producing concentration variations of the photo-product within the volume element of the optically transparent substrate, thereby producing an optically readable datum corresponding to the volume element.

Abstract: A composition for producing optical elements having a gradient structure, particularly for holographic applications, is formed by a refractive index gradient. The composition is produced from one or more polymerizable and/or polycondensable monomers and at least one biological polymer. A potential difference is generated for the directed diffusion of the monomers by inducing a local polymerization or polycondensation. The result is the formation of a refractive index gradient.

Abstract: Articles for recording a hologram are described. The articles include a holographic recording medium having a transparent polymeric binder and a photoreactive dye dispersed therein. The articles also include a first compound, dispersed in the holographic recording medium or disposed over a first surface of the holographic recording medium from which surface the hologram is viewed, that is transparent to light in the wavelength range to which the photoreactive dye is sensitive and which is capable of being converted to a converted compound that is opaque to light in the wavelength range to which the photoreactive dye is sensitive and transparent to light in a different wavelength range for viewing the hologram.

Abstract: Provided is an illumination device which illuminates an illuminated zone with a plurality of coherent light beams having mutually different wavelength ranges, so that it is possible to allow speckles to be inconspicuous. A illumination device is configured to include an optical element including a hologram recording medium and an irradiation device which illuminates the optical element with a plurality of coherent light beams having mutually different wavelength ranges so as to allow a first and second coherent light beams having different wavelength ranges to scan the hologram recording medium of the optical element. The first coherent light beams incident on respective positions of the hologram recording medium are allowed to reproduce an image superimposed on an illuminated zone, and the second coherent light beams incident on the respective positions of the hologram recording medium are allowed to reproduce an image superimposed on the illuminated zone.

Abstract: An illumination device includes: an optical element which including a hologram recording medium including a first zone and a second zone and can reproduce an image of a scattering plate; an irradiation device which irradiates the optical element with a coherent light beam such that the light beam is allowed to scan the hologram recording medium; and a polarization control unit provided on an optical path of the light beam to an illuminated zone. The light beams incident on respective positions of the hologram recording medium are allowed to reproduce the image superimposed on the illuminated zone. The polarization control unit controls polarization of the light beams such that the light beam incident on the first zone to travel toward the illuminated zone and the light beam incident on the second zone to travel toward the illuminated zone are configured with different polarization components.

Abstract: In accordance with one aspect of the present invention, a method for recording holographic data in an optical data storage medium is provided. The method includes (i) providing an optical data storage medium including: (a) a thermoplastic polymer matrix, (b) a latent acid generator, (c) a non-linear sensitizer, and (d) a reactant including a latent chromophore. The method further includes (ii) irradiating a volume element of the optical data storage medium with an interference pattern, said interference pattern including an incident radiation having a wavelength and an intensity sufficient to cause upper triplet energy transfer from the non-linear sensitizer to the latent acid generator, thereby generating an acid, wherein the latent acid generator is substantially non-responsive to said incident radiation.

Abstract: A method for producing a single-layer diffractive combiner for a head-up display having a projection unit with n light sources of ?i wavelength(s), where i=1 to n sending light towards the combiner at an angle ?p. The method includes forming interference fringes for each ?i wavelength on a photosensitive layer with an interference of two light beams from a single laser source of wavelength ?e, where the forming step is repeated n times, and each time the forming step is repeated an angle ?i between the two beams is determined according to ?i=arcsin ((?e/?i)*sin(?p)), one of the interfering beams being divergent and having a spherical wave front and the other being a plane wave, the interference of the beams generating a diffractive network with an adjustable pitch and curved contour fringe lines.

Abstract: The improvement of the performance of holographic glasses with recorded holograms as measured by a figure of merit of the holographic glasses is disclosed. The improvement in the figure of merit of the holographic glasses is obtained at least in part with the addition of arsenic in the formation of the holographic glasses. The presence of arsenic increases the figure of merit as measured at a wavelength of interest of a holographic glass with a recorded hologram as compared to a holographic glass with a recorded hologram that does not contain arsenic.

Abstract: A holography device may include a light reaction layer configured to react with light to form and remove a diffraction grating, and a metal thin film on the light reaction layer. When first light is incident on the metal thin film while the grating is formed in the light reaction layer, surface plasmon formed on the metal thin film may be diffracted so as to output a holography image. A method of processing a holography image may include recording the image on a holography device by irradiating first light to a light reaction layer to form a diffraction grating, outputting the image by irradiating second light to a metal thin film on the light reaction layer to diffract surface plasmon formed on the metal thin film, and deleting the image from the holography device by irradiating third light to the light reaction layer to remove the grating.

Abstract: A multi-layer body having a partially shaped first layer and a diffractive first relief structure shaped in a first region of a replication layer. The first layer is applied to the replication layer in the first region and, in a second region, a photosensitive layer is applied to the first layer or a photosensitive washing mask is applied thereto as a replication layer. The photosensitive layer or the washing mask is exposed through the first layer so that the photosensitive layer or washing mask is exposed differently due to the first relief structure in the first and in the second regions, and the first layer is removed using the exposed photosensitive layer or washing mask as a mask layer in the first region but not in the second region or in the second region but not in the first region.

Abstract: A method of recording a volume holographic image is described in which a holographic recording medium containing a photoreactive dye is exposed to a plurality of coherent light sources emitting at a wavelength to which the dye is sensitive, thereby forming an interference fringe pattern therein. The photoreaction occurring in the areas of constructive interference generates a periodic array of photoreacted areas of the dye and unreacted areas of the dye. This generated interference fringe pattern may contain, but does not have to contain any image or other encoded information. Selected areas of the interference fringe pattern are then exposed to actinic radiation in such a manner to partially or fully bleach, remove, or deactivate the photoreactive dye fringe pattern, thereby producing a holographic pattern, shape, or image formed by areas of the interference fringe pattern that were not bleached, removed, or deactivated.

Abstract: A recessed portion forming method for forming a plurality of recessed portions in a thermally deformable heat mode recording material layer is provided, which method includes: a recessed portion forming step of applying condensed light emitted from an optical system including a light source, to the recording material layer to form the recessed portions; an inspection light illumination step of applying inspection light to the recessed portions during or after formation of the recessed portions in the recording material layer; a detection step of detecting a light quantity of the inspection light reflected or diffracted from the recessed portions; and an output regulation step of regulating an output of the light source based upon the light quantity so that the light quantity becomes a predetermined value. Methods for manufacturing a pit-projection product, a light emitting element, and an optical element, using this method are also provided.

Abstract: The present application provides a method of manufacturing a reflection hologram. The method comprises the steps of placing a first pattern of activating material upon a layer of inactive holographic recording material to selectively activate the layer and exposing the layer to holographic recording process for producing a reflection hologram.

Abstract: A method for interlaminating a transparent embossed hologram, the transparent embossed hologram comprising a support having two sides, at least one of the two sides either itself being embossed or having a layer thereon which is embossed and a layer of a HRI-material contiguous with the embossed side or embossed layer, comprising the steps of: a) conditioning the outermost surface of the layer of inorganic HRI-material with at least one organic liquid; b) drying the outermost surface of the layer of the inorganic HRI-material thereby providing a conditioned outermost surface of the layer of inorganic HRI-material; c) applying an adhesive layer to the conditioned outermost surface; and d) laminating the outermost surface of inorganic HRI-material to an optionally transparent film, wherein the at least one organic liquid is selected from the group consisting of ketones, ethers, heterocyclic ethers, lactams, amides, halo-aliphatic compounds, nitriles and esters; wherein at least one of the support and the film i

Abstract: A composition for holographic recording is provided, comprising an inert polyphenyl ether binder capable of supporting radical polymerization, wherein the inert binder is substantially transparent in visible light, and is viscous at room temperature; a photopolymerizable part comprising a matrix forming component comprising at least one radically photopolymerizable multifunctional (meth)acrylic oligomer or monomer, and a radically polymerizable recording component; and a photoinitiation system capable of initiating radical polymerization.

Abstract: The volume hologram recording photosensitive composition provided by the present invention contains at least a fluorine-contained photoreactive compound represented by the following formula (1): R1—R3—(CF2)n-R4—R2 wherein R1 and R2 are photoreactive groups which can be bonded to each other by photoreaction, and each of R3 and R4 is independently a single bond or a bivalent hydrocarbon group having 1 to 5 carbon atoms, and n is an integer of 1 or more. This volume hologram recording photosensitive composition is used to form a recording section of a recording medium, and then the section is exposed to light, whereby a bright volume hologram can be obtained.

Abstract: A spatial light modulator may include a refraction layer including first and second regions with refractive indices different from each other; and/or a metal thin film on a lower face of the refraction layer configured to generate surface plasmons due to light incident on the metal thin film via the refraction layer. When first light is incident on the refraction layer, a phase difference between light reflected by the first and second regions may occur. A spatial light modulator may include a metal thin film and a refraction layer on the metal thin film. The refraction layer may include a first region with a first refractive index and a second region with a second refractive index different from the first refractive index. When first light is incident on the refraction layer, there may be a phase difference between light reflected from the first and second regions.

Abstract: The present invention provides a hologram recording material which is suitable for volume hologram record and attains high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage and high multiplicity in holographic memory record using not only a green laser but also a blue laser; a process for producing the same; and a hologram recording medium having the hologram recording material. A hologram recording material comprising: a metal oxide comprising Si and at least one selected from the group consisting of Ta and Zr, as metals, wherein a complexing ligand is coordinated to Ta and/or Zr; and a photopolymerizable compound. The complexing ligand is preferably selected from the group consisting of ?-dicarbonyl compounds, polyhydroxylated ligands, and ?- or ?-hydroxy acids. A hologram recording medium (11) comprising the hologram recording material layer (21).

Abstract: The present invention provides a hologram recording medium which can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low dimension change (low shrinkage) and high multiplicity in holographic memory record using a blue laser. A hologram recording medium (11) comprising at least a hologram recording material layer, wherein the hologram recording material layer (21) comprises at least a metal oxide and a photopolymerizable compound; and said hologram recording medium has a light transmittance of 50% or more at a wavelength of 405 nm, or a light reflectance of 25% or more at a wavelength of 405 nm.

Abstract: A photopolymerizable system comprises an organic-inorganic compound with a metal and an organic unit having a organic photopolymerizable subunit capable of undergoing a polymerization, a support matrix compound being polymer or capable of forming a polymer upon polymerization, and a photoinitiator system adapted to initiate the polymerization of the photopolymerizable subunits. The molecules of the organic-inorganic compound are distributed on a molecular level in the photopolymerizable system.

Abstract: The embodiments of this invention also describe to a data medium comprising a holographic memory carried on the medium, and a photonic crystal configured, firstly, to filter the light received from a broad-spectrum light source in order to select a frequency band of the said spectrum and secondly, to guide the light corresponding to the said selected frequency band so as to light the said holographic memory in a predefined direction.

Abstract: Apparatus, methods and systems for production of high efficiency refractive and diffractive elements by providing a photo-sensitizer free multicomponent glass, exposing the multi component glass to pulsed laser radiation to produce refractive indexed modulation, and heating the exposed multicomponent silicate glass to produce the high efficiency refractive and diffractive elements. The pulsed laser radiation is infrared femtosecond pulses to ultraviolet nanosecond pulses which provide ionization of glass matrix. The multicomponent glass is a photosensitive glass with high transparency in ultraviolet spectral region, e.g. silicate glass which includes silver, fluorine and bromine and does not contain photosensitizers such as cerium and antimony, PTR glass, cerium free PTR glass and cerium+antimony free PTR glass.

Abstract: We propose a method of detecting the presence of certain chemical and biochemical substances by virtue of the fact that they are, or have attached to them, either a dye molecule which acts as a photosensitizer for a holographic recording process, or another essential molecular component of the holographic recording material such as a monomer or a free radical generator. A recording material used in the process utilizes a photopolymer system consisting of a monomer and a crosslinking monomer, a free radical generator, a photosensitizer and, additionally, a polymeric binder when dry formulations are required and specifically lacks the substance to be detected. Subsequent holographic exposure records an interference pattern only where the complementary substance is present. Applications are broad ranging. Examples in diagnostics, printing, security, and environmental monitoring are given.

Abstract: A composition for holographic recording medium, which can be coated in a uniform thickness and enables to simply produce a high definition holographic recording medium is provided. And a holographic medium having a low error rate, high storage capacity, high-performance, high-density, which is produced using the composition for the holographic recording medium, is also provided. The composition comprises a (meth)acrylic acid ester group-containing polymerizable substance, an alicyclic epoxy group-containing cationical polymerizable substance of which is ring-opening polymerized by heat, and a hydroxyl group-containing substance which is reactive with the alicyclic epoxy group-containing cationical polymerizable substance. The holographic recording medium is produced by forming a holographic recording layer on a substrate by applying the composition on the base material and polymerizing the alicyclic epoxy group-containing cationical polymerizable substance and the hydroxyl group-containing substance.

Abstract: The present invention provides a lengthy volume hologram layer transfer foil capable of transferring a volume hologram layer continuously to a specified position of a transfer-receiving member. The above problem can be solved by a lengthy volume hologram layer transfer foil according to the present invention, the transfer foil is formed lengthwise and comprises: a substrate, a volume hologram layer which is formed on the substrate and in which a volume hologram is recorded, and a heat seal layer which is formed on the volume hologram layer and which contains a thermoplastic resin, the transfer foil being characterized in that it is provided with a cut portion formed so as to penetrate through the heat seal layer and to cut at least a part of the volume hologram layer, on at least a part of the full width in a direction perpendicular to the longitudinal direction thereof.

Abstract: The present invention provides a hologram recording material which attains high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage, and high multiplicity, and is suitable for volume hologram recording. Also, the present invention provides a hologram recording medium. A hologram recording material comprising: an organometallic compound at least containing at least two kinds of metals, oxygen, and an aromatic group, and having an organometallic unit wherein two aromatic groups are bonded directly to one metal; and a photopolymerizable compound containing at least a monofunctional compound (A) having one polymerizable functional group in the molecule. The hologram recording material may comprise, as the photopolymerizable compound, a polyfunctional compound (B) having two or more polymerizable functional groups in the molecule. A hologram recording medium 11 has a hologram recording material layer 21.

Abstract: The present invention provides a hologram recording material which attains high refractive index change, high flexibility, high sensitivity, low scattering, environment resistance, durability, low dimensional change and high multiplicity, and is suitable for volume hologram recording. Also, the present invention provides a hologram recording medium. A hologram recording material comprising: an organometallic compound at least containing at least two kinds of metals, oxygen, and an aromatic group and having an organometallic unit wherein two aromatic groups are bonded directly to one metal; and a photopolymerizable compound. One of the at least two kinds of metals is Si, and the metal(s) other than Si is/are preferably selected from the group consisting of Ti, Zr, Ge, Sn, Al and Zn. The organometallic unit is preferably a unit wherein two aromatic groups are bonded directly to one Si atom. A hologram recording medium (11) has a hologram recording material layer (21).

Abstract: The present invention provides a hologram recording material which attains high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage, and high multiplicity, and is suitable for volume hologram recording. Also, the present invention provides a hologram recording medium. A hologram recording material comprising: an organometallic compound at least containing at least two kinds of metals, oxygen, and an aromatic group, and having an organometallic unit wherein two aromatic groups are bonded directly to one metal; metal oxide fine particles; and a photopolymerizable compound. For example, the metal oxide fine particles are selected from the group consisting of silica fine particles, alumina fine particles, titania fine particles, zirconia fine particles, and complex oxide fine particles containing one or more kinds of metal atoms which constitute said four metal oxides. A hologram recording medium 11 has a hologram recording material layer 21.