Optical computing device and manufacturing method

Abstract

According to the present invention, in an optical computing device in which a plurality of microcells provided in a matrix form are arranged by stacking on each other, variations in cell size and position caused by dehydration shrinkage are suppressed. An optical computing device (10) comprises a plurality of optical diffraction layers (L1, L2, L3) stacked on each other. In the optical computing device (10), each of the optical diffraction layers (L1, L2, L3) has a refractive index individually set and includes a plurality of microcells (Cijk) arranged in a matrix form. The plurality of optical diffraction layers (L1, L2, L3) are contained in a dry gel (11).

Description

Technical Field

[0001] The present invention relates to an optical computing device including a plurality of photorefractive layers and a method for manufacturing such an optical computing device.

Background Art

[0002] There is known a photorefractive layer using a plurality of microcells in which the refractive index is individually set and provided in a matrix. Such a photorefractive layer is arranged by overlapping it on the optical path of the signal light, and the signal light transmitted through each photorefractive layer is made to interfere with each other, so that a photorefractive layer designed to optically execute a predetermined operation is known. Optical operations (i.e., optical computing) using photorefractive layers are faster and consume less power than electrical operations using a processor. Patent Document 1 discloses an optical neural network having an input layer, an intermediate layer, and an output layer. The above-described photorefractive layer can be used, for example, as an intermediate layer of such an optical neural network.

[0003] When applying such a technique to arithmetic processing, imaging processing, etc., it is preferable to configure the photorefractive layer so that the cell size of the microcell is about half to twice the wavelength λs of the signal light. By the cell size being about half to twice the wavelength λs, the controllability of the signal light can be enhanced. For example, when using visible light with λs = 400 nm as the signal light, a preferable cell size is considered to be 200 nm or more and 800 nm or less. Therefore, when manufacturing an optical computing device including such a photorefractive layer, it is preferable to adopt a shaping method capable of realizing a resolution on the order of nanometers (submicron).

[0004] In recent years, a shaping method called "additive manufacturing," typified by 3D printing, has attracted attention. Among them, a shaping method of two-photon 3D printing that can three-dimensionally and freely process microstructures, which is a form of photolithography, has drawn particular attention. However, when using the shaping method of two-photon 3D printing, it is difficult to achieve a resolution of less than 100 nm.

[0005] As a method for increasing the resolution of a shaped object fabricated using additive manufacturing, a shaping method called the Implosion Fabrication method has been proposed (Non-Patent Document 1 and Patent Document 2). In this shaping method, photolithography is performed in a state of a gel (in this case, a hydrogel) that contains a large amount of water, which is an example of a solvent, and is swollen. After photolithography, dehydration shrinkage is performed. By performing this dehydration shrinkage, the gel on which photolithography has been performed becomes a dry gel by shrinking to approximately 1 / 10 of its size along a single axis while approximately maintaining a similar shape. Thus, in the Implosion Fabrication method, by performing dehydration shrinkage, the final resolution can be increased to approximately 10 times the resolution at the time of photolithography. Therefore, the Implosion Fabrication method can achieve a resolution of less than 100 nm in a three-dimensional structure with a high degree of freedom.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0007]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] The inventors of the present invention considered that an optical computing device having a resolution of less than 100 nm could be realized by using a dry gel produced by the Implosion Fabrication method for each of a plurality of optical diffraction layers included in the optical computing device, and stacking each optical diffraction layer composed of a dry gel. As described above, this is because the gel used in the Implosion Fabrication method shrinks while maintaining approximately a similar shape by performing dehydration shrinkage. However, when a plurality of gels are dehydrated and shrunk, it has been found that the shrinkage rate and the uniformity of shrinkage of each gel are different.

[0009] This means that when using a dry gel produced by the Implosion Fabrication method for each of a plurality of optical diffraction layers included in the optical computing device and stacking each optical diffraction layer, the cell size and position of the microcells in each optical diffraction layer are likely to vary. When the cell size and position vary, the calculation error of the optical computing device increases, and it may become difficult to perform highly accurate calculations.

[0010] One aspect of the present invention has been made in view of the above-described problems, and an object thereof is to provide an optical computing device with less error and high calculation accuracy by suppressing variations in cell size and position caused by dehydration shrinkage in an optical computing device in which a plurality of microcells arranged in a matrix are stacked and arranged.

Means for Solving the Problems

[0011] In order to solve the above problems, an optical computing device according to one aspect of the present invention is an optical computing device including a plurality of stacked optical diffraction layers, each optical diffraction layer having a refractive index individually set and including a plurality of microcells arranged in a matrix, and the plurality of optical diffraction layers are included by a dry gel.

[0012] Also, in order to solve the above problems, a manufacturing method according to an aspect of the present invention is a manufacturing method of an optical computing device including a plurality of optically refractive layers stacked on one another. This manufacturing method includes a first step of dispersing a dye in a gel containing a solvent, a second step of patterning a pattern corresponding to the plurality of optically refractive layers by exposing the gel in which the dye is dispersed using a two-photon absorption method, a third step of removing the dye from the gel after patterning, and a fourth step of obtaining a dried gel shrunk by removing the solvent from the gel from which the dye has been removed, the dried gel including the plurality of optically refractive layers.

Effects of the Invention

[0013] According to an aspect of the present invention, in an optical computing device in which a plurality of microcells arranged in a matrix are stacked and arranged, variations in cell size and position caused by dehydration shrinkage can be suppressed.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0015] 〔First Embodiment〕 The optical computing device 10 according to the first embodiment of the present invention will be described with reference to FIG. 1. FIG. 1 is a three-view drawing of the optical computing device 10. The front view in FIG. 1 is a plan view of the upper surface among the pair of main surfaces of the optical computing device 10, namely the upper surface and the lower surface. Each of the front view and the left side view in FIG. 1 is a plan view of the front surface and the left side surface of the optical computing device 10, respectively.

[0016] <Configuration of the optical computing device> As shown in FIG. 1, the optical computing device 10 includes a drying gel 11. The drying gel 11 includes n layers (n is an integer of 2 or more, and n = 3 in the present embodiment) of optical diffraction layers Li (i is an integer of 1 ≦ i ≦ n) stacked on each other. In the present embodiment, the optical diffraction layer L1 is provided so as to be close to the lower surface of the drying gel 11, and the optical diffraction layer L2 and the optical diffraction layer L3 are stacked in this order on the optical diffraction layer L1.

[0017] Each optical diffraction layer Li includes a plurality of microcells Cijk provided in a matrix of m rows and l columns. Here, each of m and l is an integer of 2 or more, and in the present embodiment, m = 4 and l = 4. Also, j is an integer of 1 ≦ j ≦ m, and k is an integer of 1 ≦ k ≦ l. In this way, each microcell Cijk included in the optical diffraction layer Li is provided in a square matrix. Each microcell Cijk has at least its refractive index set individually and independently of each other. Also, in addition to the refractive index, the thickness Tc of each microcell Cijk may be set individually and independently of each other. When it is desired to widen the distribution of the refractive index of each microcell Cijk to such an extent that it cannot be achieved within the range of a uniform thickness, the thickness of the microcell Cijk may be made thicker. According to this configuration, when the signal light passes through, the amount of phase change that changes can be made larger than that of the microcell Cijk with a thinner thickness Tc. In the present embodiment, only the refractive index of each microcell Cijk is set individually and independently of each other, and the thickness Tc is uniform. The thickness Tc can be determined as appropriate, but typically it is about the wavelength λs of the signal light.

[0018] Here, a microcell refers to, for example, a cell with a cell size of less than 10 μm. Also, the cell size refers to the square root of the area of the cell. For example, when the planar shape of the microcell is square like the microcell Cijk, the cell size is the length Lc of one side of the cell. The lower limit of the cell size is not particularly limited, but is, for example, 1 nm.

[0019] In the optical computing device 10, the number of layers n of the optical diffraction layer Li, the number of rows m and the number of columns l of the plurality of microcells Cijk are not limited to the above-described examples and can be appropriately determined. The number of layers n may be, for example, 2 or 10. Also, the number of rows m and the number of columns l may be, for example, 200 or 4000. The number of layers n, the number of rows m, and the number of columns l can be appropriately determined according to the content of the optical computing to be executed using the optical computing device 10.

[0020] In the optical computing device 10, the signal light is incident on one main surface (for example, the lower surface) of the dry gel 11 and exits from the other main surface (for example, the upper surface) of the dry gel 11. In the front view of FIG. 1, the region where the microcells Cijk are formed is called the effective region in the optical computing device 10.

[0021] The interlayer pitch PL and the length Lc which is the cell size of the microcell Cijk are determined in relation to the wavelength λs of the signal light.

[0022] The interlayer pitch PL is preferably an integer multiple of the wavelength λs of the signal light. In the present embodiment, 40λs is adopted as the interlayer pitch PL. For example, when using a signal light with λs = 400 nm, PL = 16 μm. The interlayer pitch PL is the pitch between the adjacent optical diffraction layers Li and Li+1.

[0023] The cell size of the microcell is preferably determined within the range of λs / 2 or more and 2λs or less. That is, in the microcell Cijk, the length Lc is preferably determined within the range of λs / 2 or more and 2λs or less. For example, when using signal light with λs = 400 nm, the length Lc is preferably determined within the range of 200 nm or more and 800 nm or less. Thereby, the controllability of the signal light can be enhanced.

[0024] Also, the cell pitch Pc, which is the pitch between adjacent microcells (for example, microcell Cijk and microcell Cijk+1) within a single light diffraction layer Li, can be appropriately determined within a range exceeding the length Lc.

[0025] (Dry gel) The dry gel 11 is composed of a material having translucency with respect to the signal light. The gel constituting the dry gel 11 can be appropriately selected from the gels used in the Implosion Fabrication method (see, for example, Non-Patent Document 1, Patent Document 2, and the specification of Japanese Patent Application No. 2021-025680).

[0026] The dried gel 11 is obtained by drying the gel. A gel is a general term for solids in which the dispersed phase forms a network by being connected. The points where the dispersed phases are connected are called cross-linking points. A gel can absorb a solvent in the network and become a swollen gel. Also, when the contained solvent of the gel is dried, the gel shrinks while releasing the solvent and becomes a dried gel. Further, when it becomes a dried gel, in order to stabilize the dimensions of the dried gel, it is also possible to perform a treatment such as cross-linking to fix the structure to some extent. The shrinkage rate when comparing the gel and the dried gel varies depending on the composition of the dispersed phase and the like. In the case of the gel used in the Implosion Fabrication method described later, a typical shrinkage rate is about 1 / 10 to 1 / 100. In the optical computing device 10, in a single dried gel 11, a plurality of photorefractive layers Li are provided, each of which contains a plurality of microcells Cijk. When forming a plurality of photorefractive layers Li inside a single dried gel 11, it is possible to suppress variations in the shrinkage rate that may occur between each photorefractive layer Li. Therefore, it is possible to suppress variations in cell size and position that may occur when configuring a plurality of layers of photorefractive layers using a plurality of dried gels. Also, since it is not necessary to stack a plurality of separately provided photorefractive layers, it is possible to omit the alignment adjustment in the plurality of photorefractive layers.

[0027] Also, when demanding the accuracy when shrinking from a gel to a dried gel, it is preferable to configure the gel so as to suppress the shrinkage rate to about 1 / 10. That is, the volume of the dried gel is preferably about 1 / 1000 of the volume of the gel. The accuracy of shrinkage can also be said to be the uniformity of shrinkage in the gel. By enhancing the uniformity of shrinkage in the gel, it is possible to further suppress variations in cell size and position that may occur in each photorefractive layer Li.

[0028] Gels can be classified into chemical gels and physical gels. In chemical gels, the bonds between the dispersed phases are covalent bonds. On the other hand, in physical gels, the dispersed phases are bonded by bonds other than covalent bonds (such as intermolecular forces). Among chemical gels, gels in which the dispersed phase is a polymer compound are called polymer gels. In this embodiment, a polymer gel is used as the gel that becomes the dry gel 11 by drying the solvent.

[0029] Also, gels can be classified into hydrophilic gels, hydrophobic gels, and intermediate gels according to the polarity of the solvent that can be absorbed. Hydrophilic gels absorb solvents with high polarity (such as water and lower alcohols). Hydrophobic gels absorb solvents with low polarity (such as cyclohexane and normal hexane). Intermediate gels absorb solvents with intermediate polarity (such as diethyl ether and ethyl acetate). In this embodiment, a hydrophilic gel is used as the gel that becomes the dry gel 11 by drying the solvent. Hydrophilic gels are also called hydrogels.

[0030] The solvent content in the dry gel 11 (water content in the hydrogel) can be appropriately determined within the range of 30% or less. The solvent content in the dry gel 11 can be defined as the ratio of the mass of the contained solvent to the total mass of the dry gel 11. The lower the content rate, the smaller the size of the dry gel 11, so the cell size in each photorefractive layer Li can be reduced.

[0031] <First Modification Example> A photocomputation device 10A, which is a first modification example of the photocomputation device 10, will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view of the photocomputation device 10A. In FIG. 2, the illustration of each photorefractive layer Li included in the dry gel 11 is omitted.

[0032] As shown in FIG. 2, the photocomputation device 10A includes a dry gel 11, a transparent substrate 12A, and a resin layer 13A. The dry gel 11 of the photocomputation device 10A is the same as the dry gel 11 of the photocomputation device 10. Therefore, in this modification example, the description of the dry gel 11 is omitted.

[0033] The transparent substrate 12A is a substrate having translucency with respect to the signal light. In the present embodiment, a glass substrate made of quartz glass is used as the transparent substrate 12A. However, the material constituting the transparent substrate 12A is not limited to quartz glass and can be determined as appropriate. For example, a resin having translucency with respect to the signal light can also be used as the material constituting the transparent substrate 12A. Further, the transparent substrate 12A may be a rigid substrate or a flexible substrate. When the transparent substrate 12A is a flexible substrate, it is preferable that a frame is attached to the transparent substrate 12A so as to surround the dry gel 11. Thereby, the transparent substrate 12A can maintain flatness without being deformed.

[0034] The dry gel 11 is placed on one main surface (the upper main surface in FIG. 2) of the transparent substrate 12A.

[0035] The transparent substrate 12A is provided to support the dry gel 11 and prevent contact between the dry gel 11 and air. The transparent substrate 12A covers the lower main surface of the dry gel 11.

[0036] The resin layer 13A is composed of a resin having translucency with respect to the signal light. The resin layer 13A is provided to prevent contact between the dry gel 11 and air. The resin layer 13A is an example of a moisture-proof layer. The resin layer 13A preferably has a moisture permeability of 150 g / m 2 / 24 h or less, more preferably 50 g / m 2 / 24 h or less, and most preferably 10 g / m 2 / 24 h or less. To define the moisture permeability, the evaluation index under the test conditions of 40°C and 90% RH in the cup method test defined in JIS Z 0208 can be used. According to this configuration, the resin layer 13A can suppress the dry gel 11 from absorbing moisture in the air, so that the size of the dry gel 11 can be kept constant. The resin layer 13A covers one main surface of the transparent substrate 12A, the upper main surface and the side surface of the dry gel 11.

[0037] As the resin layer 13A, a hard coat layer used for protecting the panel surface in the display panel can be preferably used. That is, a preferable example of the resin constituting the resin layer 13A is a photocurable methacrylic resin. The hard coat layer is configured to have a hardness exceeding a predetermined value and has scratch resistance. The predetermined hardness can be determined as appropriate. In order to define the predetermined hardness, an evaluation index in a pencil hardness test defined in JIS K 5600 or the like may be used, or an evaluation index of scratch resistance measured using steel wool or the like to which an appropriate excessive load is applied by a surface hardness abrasion tester or the like may be used. By using the hard coat layer as the resin layer 13A, in addition to keeping the size of the dry gel 11 constant, it is also possible to prevent the dry gel 11 from being deformed or damaged by an external force.

[0038] Thus, the transparent substrate 12A and the resin layer 13A are configured to include the dry gel 11. The transparent substrate 12A and the resin layer 13A function as a moisture-proof layer. In the present embodiment, each of the transparent substrate 12A and the resin layer 13A is configured such that its refractive index is lower than that of the dry gel 11 and higher than that of air.

[0039] <Second Modified Example> A second modified example of the optical arithmetic unit 10 and also a modified example of the optical arithmetic unit 10A, the optical arithmetic unit 10B will be described with reference to FIG. 3. FIG. 3 is a cross-sectional view of the optical arithmetic unit 10B.

[0040] The optical arithmetic unit 10B includes a dry gel 11, a transparent substrate 12A (not shown in FIG. 3), a resin layer 13A, and a resin layer 14B. The optical arithmetic unit 10B is obtained by adding the resin layer 14B to the optical arithmetic unit 10A. Therefore, in this modified example, the resin layer 14B will be described, and the description of the dry gel 11, the transparent substrate 12A, and the resin layer 13A will be omitted.

[0041] The resin layer 14B covers the effective region of the resin layer 13A which is one of the moisture-proof layers (i.e., the region covering the upper surface of the drying gel 11). The resin layer 14B is a resin having translucency with respect to the signal light, and is configured such that its refractive index is lower than that of the resin layer 13A and higher than that of air. The resin layer 14B functions as a low refractive index layer.

[0042] The material constituting the resin layer 14B is not particularly limited, and can be appropriately selected from existing materials according to the refractive index. The resin layer 14B may be constituted by an acrylate resin added with fluorine, or may be constituted by a resin in which fine air bubbles are dispersed inside. When dispersing air bubbles inside the resin, the size of the air bubbles is preferably less than the wavelength λs of the signal light.

[0043] Note that one aspect of the optical computing device 10B may further include a resin layer covering the effective region of the transparent substrate 12A which is the other moisture-proof layer (i.e., the region covering the lower surface of the drying gel 11). This resin layer may be configured in the same manner as the resin layer 14B.

[0044] <The Third Modification Example> The optical computing device 10C which is the third modification example of the optical computing device 10 will be described with reference to FIG. 4. FIG. 4 is a cross-sectional view of the optical computing device 10C.

[0045] The optical computing device 10C includes a drying gel 11, a pair of transparent substrates 12C1 and 12C2, and a resin layer 13C.

[0046] The transparent substrate 12C1 is configured in the same manner as the transparent substrate 12A of the optical computing device 10A. That is, the transparent substrate 12C1 covers the lower surface of the drying gel 11.

[0047] The transparent substrate 12C2 is a glass substrate configured in the same manner as the transparent substrate 12C1. The transparent substrate 12C2 is placed on the upper surface of the drying gel 11 so as to sandwich the drying gel 11 together with the transparent substrate 12C1. Therefore, the transparent substrate 12C2 covers the upper surface of the drying gel 11.

[0048] The resin layer 13C is made of the same resin as the resin constituting the resin layer 13A of the optical computing device 10A. However, the resin layer 13C is filled between the transparent substrate 12C1 and the transparent substrate 12C2 and covers the side surface of the dry gel 11.

[0049] The transparent substrate 12C1, the transparent substrate 12C2, and the resin layer 13C function as a moisture-proof layer.

[0050] Similar to the transparent substrate 12A, the transparent substrate 12C1 and the transparent substrate 12C2 may be a rigid substrate or a flexible substrate.

[0051] In the present embodiment, each of the transparent substrate 12C1, the transparent substrate 12C2, and the resin layer 13C is configured such that its respective refractive index is lower than the refractive index of the dry gel 11 and higher than the refractive index of air.

[0052] 〔Second Embodiment〕 The manufacturing method M1 according to the second embodiment of the present invention will be described with reference to FIG. 5. FIG. 5 is a flowchart of the manufacturing method M1. In the present embodiment, the manufacturing method M1 will be described by taking the case of manufacturing the optical computing device 10A as an example. However, the first step S11 to the fourth step S14 included in the manufacturing method M1 can be applied to any of the cases of manufacturing the optical computing device 10, the optical computing device 10B, and the optical computing device 10C.

[0053] <Gel> In the present embodiment, the manufacturing method M1 will be described starting from the state where a gel containing a solvent is placed on the upper surface of the transparent substrate 12A.

[0054] As the gel used in this initial state, it can be appropriately selected from gels that can be used in the Implosion Fabrication method.

[0055] Regarding the gel used in the initial state, it is described in, for example, Non-Patent Document 1 and Patent Document 2. Further, the multi-block copolymer described in the specification of Japanese Patent Application No. 2021-025680 may be adopted as the gel used in the initial state. In this multi-block copolymer, a first segment and a second segment each composed of one or more block polymers are alternately bonded. Here, the first segment has hydrophobicity, and the second segment has hydrophilicity. Moreover, this multi-block copolymer is configured such that the total number of segments is 3 or more.

[0056] <Configuration of the manufacturing method> As shown in FIG. 5, the manufacturing method M1 includes a first step S11, a second step S12, a third step S13, a fourth step S14, and a fifth step S15.

[0057] The first step S11 is a step of dispersing a dye in a gel containing a solvent. This dye can be appropriately selected according to the composition of the gel used in the initial state (see, for example, Non-Patent Document 1, Patent Document 2, and the specification of Japanese Patent Application No. 2021-025680).

[0058] The second step S12 is a step of patterning a pattern corresponding to each light diffraction layer Li of a plurality of layers by exposing a gel in which a dye is dispersed using a two-photon absorption method. That is, in the second step S12, a laser beam having intensities set individually and independently of each other is irradiated onto the region corresponding to each microcell Cijk. The dispersoid binds to the dye by absorbing two photons of the laser beam. Therefore, an amount of dye corresponding to the intensity of the laser beam binds to each microcell Cijk. Fine particles having a refractive index different from that of the dry gel can be further bound to the dye introduced according to the intensity of this laser beam according to the amount of the dye, whereby the refractive index in each microcell Cijk can be set individually and independently of each other. Examples of the fine particles having a refractive index higher than that of the dry gel include titanium oxide nanoparticles and nanodiamonds. Examples of the fine particles having a refractive index lower than that of the dry gel include fluoride nanoparticles.

[0059] Patterning using the two-photon absorption method is a form of stereolithography and is also referred to as two-photon 3D printing hereinafter. In the two-photon absorption method, not only can the position of the focus of the irradiated laser beam (excitation light) be moved in the in-plane direction of the main surface in the dry gel 11, but also in the normal direction of the main surface. Therefore, in two-photon 3D printing, the microstructure can be freely processed three-dimensionally.

[0060] The third step S13 is a step of removing the dye from the gel by washing the gel patterned in the second step S12. By performing the third step S13, the dye bound to the dispersoid remains in the region corresponding to each microcell Cijk in the gel, and the dye not bound to the dispersoid is removed from the gel.

[0061] The fourth step S14 is a step of removing the solvent from the gel from which the dye has been removed in the third step S13. By performing the fourth step S14, the gel shrinks and becomes a dried gel. The solvent content rate in the dried gel 11 can be appropriately determined within the range of 30% or less. The lower the content rate, the smaller the size of the dried gel 11, so that the cell size in each photorefractive layer Li can be reduced.

[0062] The fifth step S15 is a step of applying a liquid resin that will become the resin layer 13A to the upper surface of the transparent substrate 12A and the surface of the dried gel 11, and curing this liquid resin. When the liquid resin cures, the resin layer 13A is formed on the upper surface of the transparent substrate 12A and the surface of the dried gel 11, and the dried gel 11 is enclosed by the transparent substrate 12A and the resin layer 13A. The transparent substrate 12A and the resin layer 13A are an example of a moisture-proof layer.

[0063] When manufacturing the optical arithmetic device 10B, after the fifth step S15, a step of forming a resin layer 14B, which is an example of a low refractive index layer, may be added to at least the region of the resin layer 13A that covers the dried gel 11.

[0064] 〔Supplementary Notes〕 The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0065] 〔Summary〕 The optical arithmetic device according to the first aspect of the present invention is an optical arithmetic device including a plurality of photorefractive layers stacked on one another. Each photorefractive layer includes a plurality of microcells whose refractive indices are individually set and arranged in a matrix, and the plurality of photorefractive layers are enclosed by a dried gel.

[0066] According to the above configuration, since the multiple-layer photorefractive layers are included in a single dry gel, an optical computing device can be manufactured without using multiple dry gels. Therefore, variations in cell size and position that may occur when configuring multiple-layer photorefractive layers using multiple dry gels can be suppressed. In an optical computing device with suppressed variations in cell size and position fabricated by applying this, there are few errors and it is possible to perform more accurate computations.

[0067] Also, in an optical computing device that sequentially acts multiple photorefractive layers on the signal light, in an optical computing device where each photorefractive layer is provided in a separate dry gel, it is important to adjust the position and direction of each photorefractive layer with respect to the signal light to predetermined positions and directions. This is because if the position and direction of the photorefractive layer with respect to the signal light deviate from the predetermined positions and directions, it becomes difficult to exert the intended effect on the signal light. Hereinafter, this adjustment will be referred to as alignment adjustment. According to the above configuration, since multiple photorefractive layers are provided in a single dry gel, alignment adjustment can be omitted during manufacturing. Note that what can be adjusted by this alignment adjustment is only the positional deviation between each photorefractive layer, that is, the error due to the in-plane horizontal movement. In alignment adjustment, for example, it is not possible to completely adjust the deviation in cell size of each photorefractive layer caused by different shrinkage rates of each photorefractive layer, but according to the above configuration where multiple photorefractive layers are provided in a single dry gel, such a deviation in cell size can also be suppressed.

[0068] Further, in the optical computing device according to the second aspect of the present invention, in addition to the configuration of the optical computing device according to the first aspect described above, a moisture-proof layer having translucency with respect to the signal light and further including the dry gel is adopted.

[0069] According to the above configuration, since the contact between the dry gel and air can be blocked, it is possible to suppress the dry gel from absorbing moisture contained in the air. Therefore, the size of the dry gel can be kept constant regardless of the external environment.

[0070] Further, in the optical computing device according to the third aspect of the present invention, in addition to the configuration of the optical computing device according to the second aspect described above, the refractive index of the moisture-proof layer is lower than the refractive index of the dry gel and higher than the refractive index of air.

[0071] According to the above configuration, it is possible to suppress the reflection that may occur when the moisture-proof layer is not provided, that is, the reflection at the interface between the dry gel and air.

[0072] Further, in the optical computing device according to the fourth aspect of the present invention, in addition to the configuration of the optical computing device according to the third aspect described above, a low refractive index layer that covers the effective region of the moisture-proof layer and has a refractive index lower than that of the moisture-proof layer and higher than that of air is further provided.

[0073] According to the above configuration, it is possible to suppress the reflection that may occur when the low refractive index layer is not provided, that is, the reflection at the interface between the moisture-proof layer and air.

[0074] The manufacturing method according to the fifth aspect of the present invention is a manufacturing method of an optical computing device including a plurality of layers of photorefractive layers stacked on each other. This manufacturing method includes a first step of dispersing a dye in a gel containing a solvent, a second step of patterning a pattern corresponding to the plurality of layers of photorefractive layers by exposing the gel in which the dye is dispersed using a two-photon absorption method, a third step of removing the dye from the patterned gel, and a fourth step of obtaining a dried gel shrunk by removing the solvent from the gel from which the dye has been removed and including the plurality of layers of photorefractive layers.

[0075] According to the above configuration, the same effects as those of the optical computing device according to the first aspect are achieved.

[0076] Further, in the manufacturing method according to the sixth aspect of the present invention, in addition to the configuration of the manufacturing method according to the fifth aspect described above, a moisture-proof layer having translucency with respect to the signal light is used, and the method further includes a fifth step of including the dry gel.

[0077] According to the above configuration, the same effects as those of the optical arithmetic unit according to the second aspect can be obtained.

Explanation of Reference Numerals

[0078] 10, 10A, 10B, 10C Optical arithmetic unit 11 Dry gel Li Optical diffraction layer Cijk Microcell 12A, 12C1, 12C2 Transparent substrate 13A, 14B, 13C Resin layer

Claims

1. An optical computing device comprising a plurality of optically refractive layers stacked on top of each other, each optical refractive layer having an individually set refractive index so as to optically perform a predetermined operation, and including a plurality of microcells arranged in a matrix, wherein the plurality of optical refractive layers are encapsulated by a dry gel, characterized in that it is an optical computing device.

2. A moisture-proof layer having light-transmitting properties with respect to signal light, further comprising a moisture-proof layer encapsulating the dry gel, characterized in that it is the optical computing device according to Claim 1.

3. The refractive index of the moisture-proof layer is lower than that of the dry gel and higher than that of air, characterized in that it is the optical computing device according to Claim 2.

4. A low refractive index layer covering the effective area of the moisture-proof layer, further comprising a low refractive index layer having a refractive index lower than that of the moisture-proof layer and higher than that of air, characterized in that it is the optical computing device according to Claim 3.

5. A method for manufacturing an optical computing device comprising a plurality of optically refractive layers stacked on top of each other, each having an individually set refractive index so as to optically perform a predetermined operation, a first step of dispersing a dye in a gel containing a solvent, a second step of patterning a pattern corresponding to the plurality of optical refractive layers by exposing the gel in which the dye is dispersed using a two-photon absorption method, a third step of removing the dye from the patterned gel, and a fourth step of obtaining a dried gel shrunk by removing the solvent from the gel from which the dye has been removed, the dried gel including a plurality of optical refractive layers, characterized in that it includes these steps.

6. further comprising a fifth step of using a moisture-proof layer having light-transmitting properties with respect to signal light to encapsulate the dry gel, characterized in that it is the manufacturing method according to Claim 5.

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