Diffractive optical element and method for manufacturing diffractive optical element

Abstract

Provided are a diffractive optical element that is thin and highly amenable to mass production, and that has high light condensing performance and is applicable to fine pixel pitch, and a method for manufacturing the diffractive optical element.　The diffractive optical element causes diffraction of incident light in a wavelength range of 410-1,100 nm, and comprises: a substrate that transmits incident light; and a light shielding resin layer that forms unevenness on the main surface of the substrate and forms a diffraction pattern that is substantially concentric when viewed in a direction orthogonal to the main surface of the substrate, the light shielding resin layer being formed by a curable resin composition and shielding at least some wavelengths of light in the incident light.

Description

Diffractive optical element and method for manufacturing the same

[0001] The present invention relates to a diffractive optical element, and more particularly to a diffractive optical element applicable to imaging, optical sensors, displays, and optical communications. The present invention also relates to a method for manufacturing a diffractive optical element.

[0002] Optical components are used to appropriately control light in image sensors, optical sensors, displays, and optical communications.

[0003] In recent years, there has been a growing demand for thinner optical components. For example, in the case of camera modules in smartphones and mobile phones, the lens is the factor that determines the height of the camera module, and the increase in camera module size due to the increase in sensor area has become a problem, leading to a strong demand for thinner optical elements.

[0004] Optical sensors, such as fingerprint authentication sensors, face authentication sensors, proximity sensors, ambient light sensors, and pulse oximeters, are used in smartphones and smartwatches to detect light of multiple wavelengths, but optical sensors are often built into the back of the display, and there is a strong demand for thinner and more compact optical components. These optical sensors also increase the thickness of the device, so there is a strong demand for thinner devices.

[0005] Furthermore, among display devices, wearable display elements such as glasses and head-mounted displays in devices for AR (Augmented Reality), VR (Virtual Reality), and MR (Mixed Reality) use holographic optical elements that utilize a grating structure and total reflection, or pancake lenses. However, optical elements corresponding to the three colors of red, green, and blue are required, and if ordinary optical lenses are used, the thickness and weight become an issue.

[0006] In order to cope with the trend toward thinner optical components, various types of diffractive optical elements have been reported in recent years.

[0007] For example, Patent Document 1 reports a metalens, an optical element that focuses light with high precision despite having a thickness of 1 μm or less, by optimizing the arrangement of fine pillars made of a high refractive index material. However, metalens requires nanometer-level structural control, and electron beam lithography and atomic layer deposition (ALD) must be used to create the high refractive index pillar structure, which is a time-consuming method, resulting in a very complicated manufacturing process with low productivity.

[0008] Another example of a planar optical element is a Fresnel zone plate, which achieves light-gathering performance by combining a transmissive region and a light-blocking region. Patent Document 2 proposes the use of a Fresnel zone plate for optical fiber optical coupling, while Patent Document 3 proposes that the Fresnel zone plate be disposed directly above a CMOS image sensor as a replacement for a color filter. In addition to the Fresnel zone plate, Patent Document 4 discloses light-gathering elements such as a fractal zone plate and a photon sieve. Patent Document 5 discloses a Fresnel lens and a Fresnel phase difference lens using an optical multilayer film with wavelength-specific reflection characteristics. Patent Document 6 discloses a Fresnel lens with improved chromatic aberration using multiple color filters.

[0009] However, the Fresnel zone plates, fractal zone plates, and photon sieves represented by Patent Documents 2 to 4 require the formation of a mask on a metal vapor deposition layer by lithography, followed by metal etching and mask development, resulting in low productivity methods similar to Patent Document 1. Furthermore, the optical multilayer film used in Patent Document 5 requires high film thickness accuracy, necessitating high-precision production with reduced formation speed. Furthermore, the Fresnel zone plate must be formed by subsequent etching, resulting in similarly low productivity methods. Furthermore, Patent Documents 2 to 6 do not achieve the high light-focusing performance required for imaging applications compatible with fine pixels, and design guidelines for achieving this light-focusing performance are unknown. Light-focusing performance can be determined by the full width at half maximum (FWHM), which is the width at which the electromagnetic field intensity at the most focused point is ½. For imaging applications applicable to fine sensors, a light-focusing performance of FWHM 2.51 μm or less is required. However, there are no guidelines for obtaining high light-collecting performance suitable for imaging applications in diffractive imaging elements made of Fresnel zone plates, fractal zone plates, or photon sieves, and the diffractive optical elements of Patent Documents 2 to 6 are not suitable for use as fine imaging elements or sensor elements.Furthermore, they are not diffractive optical elements that can be used as diffractive optical elements in fine display devices such as wearable display elements such as AR or MR glasses or head-mounted displays, or hologram optical elements designed for the three colors of red, green, and blue using a grating structure and total reflection, or for near-infrared light.

[0010] Other known planar optical elements with high productivity include Fresnel lenses and diffractive optical element lenses such as those described in Non-Patent Document 1, which have a light-condensing performance achieved by designing a fine structure.

[0011] However, the Fresnel lens that focuses light using this fine structure and the diffractive optical element of Non-Patent Document 1 are diffractive optical elements that do not have absorption properties and use a positive resist in which the exposed portion dissolves, and due to the influence of light scattering at the interface formed by the fine structure, the light focusing performance is greater than 2.51 μm, which is insufficient for application to fine sensor elements or pixel elements. Note that the diffractive optical element described in Non-Patent Document 1 is intended for infrared light with a wavelength of 8 μm or more, and no consideration has been given to the wavelength range of visible light or the wavelength range of short infrared light with a wavelength of 2 μm or less.

[0012] International Publication No. 2017 / 176921 Japanese Patent Application Laid-Open No. 2009-187010 Japanese Patent Application Laid-Open No. 2007-109801 Japanese Patent Application Laid-Open No. 2016-518616 U.S. Patent No. 5,257,132 International Publication No. 2022 / 264488

[0013] PNAS Vol. 116 Jno. 43 21375-21378 (2019)

[0014] Conventional diffractive optical elements have only been fabricated using methods that require complicated procedures and are not suitable for mass production, or that result in low light-collecting performance. An object of the present invention is to provide a thin diffractive optical element that can be mass-produced and has high light-collecting performance that can accommodate fine pixel pitches, and a method for manufacturing such a diffractive optical element.

[0015] The present inventors have conducted extensive research to solve the above problems, and as a result, examples of the embodiments of the present invention are shown below.

[0016] [1] A diffractive optical element that diffracts incident light having a wavelength in the range of 410 nm to 1,100 nm, comprising: a substrate that transmits the incident light; and a light-shielding resin layer that is formed of a curable resin composition and that has irregularities on a main surface of the substrate and that forms a diffraction pattern that is substantially concentric when viewed in a direction perpendicular to the main surface of the substrate, and that shields light of at least some of the wavelengths of the incident light.

[0017] Here, the term "substantially concentric" is used to include not only a shape composed of multiple annular rings centered on a certain point, but also a shape that is rotationally symmetrical due to a predetermined shape being arranged in the circumferential direction around a certain point. Rotational symmetry refers to a shape that is substantially the same when rotated (360 / n) degrees around the center. Here, n is an integer of 2 or more. For example, in the case of a diffraction pattern in which light-shielding resin layers are arranged at equal intervals in the circumferential direction, the number of light-shielding resin layers is determined according to the number of light-shielding resin layers, the number of gaps between the light-shielding resin layers, or the sum of these.

[0018] [2] The diffractive optical element according to the above [1], wherein the shape of the diffraction pattern of the light-shielding resin layer when viewed in a direction perpendicular to the main surface of the substrate is any one of a Fresnel zone plate shape, a linear zone plate shape, and a fractal zone plate shape.

[0019] [3] The diffractive optical element according to the above [2], wherein the light-shielding resin layer includes at least one resin layer having a maximum width in the radial direction of 2 μm or less.

[0020] [4] The diffractive optical element according to the above [2] or [3], wherein the light-shielding resin layer has a thickness of 2 μm or less.

[0021] [5] A diffractive optical element according to any one of [2] to [4] above, wherein when light having a wavelength λ in the range of 410 nm to 1,100 nm is incident as a parallel beam from a direction perpendicular to the main surface of the substrate, the focal length f is defined as a distance between the substrate and a focusing position D of the light having the wavelength λ, and the focal length f is in the range of 2 μm to 100 cm.

[0022] [6] A diffractive optical element according to any one of the above [2] to [5], wherein when light having a wavelength λ in the range of 410 nm to 1,100 nm is incident as a parallel beam from a direction perpendicular to the main surface of the substrate, the focal length f is defined as a distance between the substrate and a focusing position D of the light of wavelength λ, and the focal length f is defined as a distance between the substrate and the focal length f, and the diameter of the circumscribed circle of the diffraction pattern when viewed in a direction perpendicular to the main surface of the substrate.

[0023] [7] The diffractive optical element according to any one of [2] to [6] above, wherein the light-shielding resin layer includes a structure in which a boundary at which a region of the light-shielding resin layer changes into a region other than the light-shielding resin layer is 250 or more in a radial direction from the center of the diffraction pattern toward the outer edge when viewed in a direction perpendicular to the main surface of the substrate.

[0024] [8] The diffractive optical element according to the above [1], wherein the shape of the diffraction pattern of the light-shielding resin layer when viewed in a direction perpendicular to the main surface of the substrate is a photon sieve plate shape.

[0025] [9] The diffractive optical element according to the above [8], wherein the light-shielding resin layer has a thickness of 2 μm or less.

[0026]

[10] The diffractive optical element according to the above [9], wherein when light having a wavelength λ in the range of 410 nm to 1,100 nm is incident as a parallel beam from a direction perpendicular to the main surface of the substrate, the focal length f is defined as a distance between the substrate and a focusing position D of the light having the wavelength λ, and the focal length f is 2 μm or more and 100 cm or less.

[0027]

[11] The diffractive optical element according to [9] or

[10] above, wherein when light having a wavelength λ in the range of 410 nm to 1,100 nm is incident as a parallel beam from a direction perpendicular to the main surface of the substrate, the focal length f is defined as a distance between the substrate and a focusing position D of the light having the wavelength λ, and the focal length f is defined as a distance between the substrate and the focal length f, and the diameter of the circumscribed circle of the diffraction pattern when viewed in a direction perpendicular to the main surface of the substrate.

[0028]

[12] The diffractive optical element according to any one of [9] to

[11] above, wherein the light-shielding resin layer includes a structure in which a boundary at which a region of the light-shielding resin layer changes into a region other than the light-shielding resin layer is 250 or more in a radial direction from the center of the diffraction pattern toward the outer edge when viewed in a direction perpendicular to the main surface of the substrate.

[0029]

[13] The diffractive optical element according to any one of the above [1] to

[12] , wherein the curable resin composition is a radiation-sensitive curable resin composition.

[0030]

[14] The diffractive optical element according to the above

[13] , wherein the curable resin composition is an electromagnetic wave curable resin composition or an electron beam curable resin composition.

[0031]

[15] The diffractive optical element according to the above

[14] , wherein the curable resin composition is an ultraviolet curable resin composition.

[0032]

[16] The diffractive optical element according to any one of the above [1] to

[15] , wherein the light-shielding resin layer has a minimum transmittance of less than 50% for light of any wavelength λ within a wavelength range of 410 nm to 1,100 nm per 1 μm of optical path length for the incident light.

[0033]

[17] The diffractive optical element according to the above

[16] , wherein the light-shielding resin layer has a maximum extinction coefficient per 1 μm of optical path length for the incident light in the range of 0.0001 to 1.1.

[0034]

[18] The diffractive optical element according to the above

[16] or

[17] , wherein the light-shielding resin layer has a maximum transmittance of 50% or more for light of any wavelength λ within a wavelength range of 410 nm to 1,100 nm per 1 μm of optical path length for the incident light.

[0035]

[19] A method for producing a diffractive optical element applicable to incident light having a wavelength within a range of 410 nm to 1,100 nm, comprising: a step (A) of preparing a substrate that transmits the incident light; a step (B) of applying a material containing a curable resin composition onto a main surface of the substrate to form a coating film; a step (C) of curing a part of the coating film to form a light-shielding resin layer that shields the incident light on a part of the main surface of the substrate; and a step (D) of removing, after step (C), the coating film in a part different from the light-shielding resin layer from the main surface of the substrate.

[0036] According to the present invention, it is possible to provide a diffractive optical element that is thin, highly mass-producible, and has high light-collecting performance that can accommodate fine pixel pitches, and a method for manufacturing the diffractive optical element.Furthermore, it is possible to provide a thin optical sensor or a thin display device that has excellent characteristics for adjusting the light-collecting position and performance according to wavelength.

[0037] 1 is a diagram showing an example of a Fresnel zone plate shape; FIG. 2 is a diagram showing a method for counting light-shielding regions; FIG. 3 is a diagram showing a schematic cross-sectional view of a diffractive optical element cut by a plane perpendicular to the main surface of a substrate; FIG. 4 is a diagram showing a state in which parallel light is incident on a diffractive optical element; FIG. 5 is a diagram showing an example of a Fresnel zone plate shape combining pattern shapes of different designs in the radial direction; FIG. 6 is a diagram showing an example of a linear zone plate shape; FIG. 7 is a diagram showing a schematic diagram of a region division pattern in a fractal zone plate shape; FIG. 8 is a diagram showing an example of a fractal zone plate shape; FIG. 9 is a diagram showing an example of a photon sieve plate shape; FIG. 10 is a graph showing the refractive index and extinction coefficient spectra of a curable resin composition 1 having a thickness of 1 μm; FIG. 11 is a graph showing the refractive index and extinction coefficient spectra of a curable resin composition 2 having a thickness of 1 μm; FIG. 12 is a graph showing the refractive index and extinction coefficient spectra of a curable resin composition 3 having a thickness of 1 μm; and FIG. 13 is a graph showing the refractive index and extinction coefficient spectra of a curable resin composition 5 having a thickness of 1 μm. 14B is an enlarged image of the area within the dotted line frame in the center of FIG. 14A. FIG. 14B is an enlarged image of the area within the dotted line frame in the center of FIG. 14B. FIG. 14C is an image of a camera equipped with a Fresnel zone plate obtained in Example 3. FIG. 15A is an image of a camera equipped with a Fresnel zone plate obtained in Example 3. FIG. 15B is an image of a camera equipped with a Fresnel zone plate obtained in Example 3. FIG. 15 ...

[0038] Hereinafter, embodiments of the diffractive optical element of the present invention and a manufacturing method for a diffractive optical element of the present invention will be described with reference to the drawings as appropriate. However, the diffractive optical element of the present invention and the manufacturing method for a diffractive optical element of the present invention can be implemented in many different forms, and should not be construed as being limited to the description of the embodiments exemplified below. To clarify the explanation, the drawings may schematically depict the width, thickness, shape, etc. of each part compared to the actual form, but these are merely examples and do not limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same or similar symbols (symbols simply having a suffix such as "'" after the number), and detailed descriptions may be omitted as appropriate.

[0039] In this specification, "up" refers to a relative position based on the main surface of the support substrate (for example, the surface on which the solid-state imaging element is disposed), and the direction away from the main surface of the support substrate is "up". In this drawing, "up" refers to the upward direction as viewed from the paper. "Up" also includes the case where the substrate is in contact with the top of an object (i.e., "on") and the case where the substrate is positioned above an object (i.e., "over"). Conversely, "down" refers to a relative position based on the main surface of the support substrate, and the direction approaching the main surface of the support substrate is "down". In this drawing, "down" refers to the downward direction as viewed from the paper.

[0040] <Substrate> A substrate having a transmittance of 50% or more at any wavelength between 410 nm and 1,100 nm is used. Examples of such transparent substrates include silicate glass substrates, borosilicate glass substrates, phosphate glass substrates, fluorophosphate glass substrates, plastic substrates, and resin film substrates. Materials having a glass transition temperature of 140°C or higher and a surface roughness Ra of less than 200 nm are preferred. The substrate may contain a near-infrared absorber, and may contain at least one selected from inorganic near-infrared absorbers such as cesium tungsten oxide and copper (II) oxide, near-infrared absorbers utilizing surface plasmons such as gold nanorods, and organic near-infrared absorbers.

[0041] The substrate is preferably made of multiple layers from the viewpoints of crack resistance, ease of addition of a light absorber, and imparting functions and effects. Functions imparted to the substrate include electrical conductivity, antistatic effect, anti-adhesion effect, scratch prevention effect, anti-fogging property, heat resistance improvement effect, gas barrier property, high elasticity, scratch removal effect, flatness, rough surface, moisture absorption, anti-aging effect, near-infrared cutoff property, etc. The substrate may have a dielectric multilayer film for the purpose of imparting control of the transmission wavelength.

[0042] <Curable Resin Composition> The curable resin composition according to the present invention has absorption characteristics with a maximum absorption wavelength in the wavelength range of 410 to 1,100 nm. More preferably, it has a maximum absorption wavelength in the wavelength range of 410 to 1,000 nm, and even more preferably, it has a maximum absorption wavelength in the wavelength range of 420 to 1,000 nm. By having absorption characteristics in this wavelength range, the refractive index of the obtained curable resin composition at any wavelength in the wavelength range of 410 to 1,100 nm can be made to exceed 1.6, thereby improving the light-collecting performance of the obtained diffractive optical element. The curable resin composition contains a colorant and a polymerizable compound.

[0043] The curable resin composition according to the present invention is preferably a radiation-sensitive curable resin composition, and examples of the radiation used here include ultraviolet rays, far ultraviolet rays, X-rays, and charged particle beams. Examples of ultraviolet rays include g-rays (wavelength 436 nm) and i-rays (wavelength 365 nm). Examples of far ultraviolet rays include KrF excimer lasers. Examples of X-rays include synchrotron radiation. Examples of charged particle beams include electron beams. Of these types of radiation, ultraviolet rays are preferred, and among ultraviolet rays, radiation including g-rays and / or i-rays is particularly preferred.

[0044] The colorant according to the present invention has a maximum absorption wavelength in the range of 410 to 1,100 nm. There are no particular limitations on the colorant as long as it has the above maximum absorption wavelength, but at least one selected from pigments and dyes is preferred.

[0045] The pigment may be either an organic pigment or an inorganic pigment, and preferred specific examples of organic pigments include, in terms of Color Index (C.I.) names, C.I. Pigment Red 166, C.I. Pigment Red 177, C.I. Pigment Red 224, C.I. Pigment Red 242, C.I. Pigment Red 254, C.I. Pigment Red 264, C.I. Pigment Green 7, C.I. Pigment Green 36, C.I. Pigment Green 58, C.I. Pigment Blue 15:6, C.I. Pigment Blue 80, C.I. Pigment Yellow 83, C.I. Pigment Yellow 129, C.I. Pigment Yellow 138, C.I. Pigment Yellow 139, C.I. Examples of inorganic pigments include C.I. Pigment Yellow 150, C.I. Pigment Yellow 180, C.I. Pigment Yellow 185, C.I. Pigment Yellow 211, C.I. Pigment Orange 38, C.I. Pigment Violet 23, carbon nanotubes, and fullerenes. Furthermore, the colorant may contain a pigment that does not have a maximum absorption wavelength in the wavelength range of 410 to 1100 nm. Examples of colorants that do not have a maximum absorption wavelength in the wavelength range of 410 to 1100 nm include carbon black, titanium black, and graphene. Specific examples of preferred inorganic pigments include titanium oxide, strontium titanate, barium titanate, zinc oxide, magnesium oxide, zirconium oxide, aluminum oxide, barium sulfate, silica, talc, mica, aluminum hydroxide, calcium silicate, aluminum silicate, and zinc sulfide.

[0046] Examples of the dyes include pyrazole azo compounds, anilino azo compounds, triarylmethane compounds, anthraquinone compounds, anthrapyridone compounds, benzylidene compounds, oxonol compounds, pyrazolotriazole azo compounds, pyridone azo compounds, cyanine compounds, phenothiazine compounds, pyrrolopyrazole azomethine compounds, xanthene compounds, phthalocyanine compounds, benzopyran compounds, indigo compounds, pyrromethene compounds, triarylmethane compounds, cyanine compounds, and azo compounds. Quinophthalone compounds and the like can also be used as yellow dyes. Examples of near-infrared absorbing dyes include pyrrolopyrrole compounds, rylene compounds, oxonol compounds, squarylium compounds, cyanine compounds, croconium compounds, phthalocyanine compounds, naphthalocyanine compounds, pyrylium compounds, azulenium compounds, indigo compounds, and pyrromethene compounds. In addition, squarylium compounds, pyrrole ring-containing compounds, squarylium compounds having an aromatic ring at the amide α-position, compounds having a croconium skeleton, dihydrocarbazole bis-type squarylium compounds, etc. can also be used.

[0047] In the present invention, the pigments and dyes may be used either alone or in combination of two or more.

[0048] When a pigment is used as a colorant in the present invention, the pigment may be purified, if desired, by recrystallization, reprecipitation, solvent washing, sublimation, vacuum heating, or a combination thereof before use. Furthermore, the pigment may be used after modifying its particle surface with a resin, if desired. Examples of resins that modify the pigment particle surface include vehicle resins and various commercially available resins for dispersing pigments. Furthermore, the pigment may be used after micronizing primary particles by so-called salt milling.

[0049] When a pigment is used as a colorant in the present invention, it may be used together with a dispersant or a dispersing aid, if desired. Examples of the dispersant include cationic, anionic, and nonionic dispersants, but polymer dispersants are preferred. Specific examples include urethane dispersants, polyethyleneimine dispersants, polyoxyethylene alkyl ether dispersants, polyoxyethylene alkylphenyl ether dispersants, polyethylene glycol diester dispersants, sorbitan fatty acid ester dispersants, polyester dispersants, and acrylic dispersants.

[0050] <Polymerizable Compound> The polymerizable compound of the present invention has a polymerizable functional group, but is not particularly limited thereto. Examples of the polymerizable functional group include an ethylenically unsaturated group, an oxiranyl group, an oxetanyl group, an N-alkoxymethylamino group, a hydrosiloxane group, and a vinylsilyl group. Examples of the ethylenically unsaturated group include a vinyl group, a styryl group, an allyl group, a (meth)acryloyl group, a (meth)acrylamide group, and a maleimide group, with a (meth)acryloyl group being preferred. From the viewpoint of dimensional stability, a hydrosiloxane group and a vinylsilyl group are preferred. The polymerizable compound used in the present invention is preferably selected from the group consisting of compounds having two or more polymerizable functional groups in the molecule.

[0051] Examples of the compound having two or more (meth)acryloyl groups in the molecule include polyfunctional (meth)acrylates obtained by reacting an aliphatic polyhydroxy compound with (meth)acrylic acid, caprolactone-modified polyfunctional (meth)acrylates, alkylene oxide-modified polyfunctional (meth)acrylates, polyfunctional urethane (meth)acrylates obtained by reacting a (meth)acrylate having a hydroxyl group with a polyfunctional isocyanate, and polyfunctional (meth)acrylates having a carboxyl group obtained by reacting a (meth)acrylate having a hydroxyl group with an acid anhydride. Examples of the aliphatic polyhydroxy compounds include divalent aliphatic polyhydroxy compounds such as ethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; and trivalent or higher aliphatic polyhydroxy compounds such as glycerin, trimethylolpropane, pentaerythritol, and dipentaerythritol.

[0052] Examples of the (meth)acrylate having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and glycerol dimethacrylate; and examples of the polyfunctional isocyanate include tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethylene diisocyanate, and isophorone diisocyanate. Examples of the acid anhydrides include dibasic acid anhydrides and tetrabasic acid dianhydrides. Specific examples of these include the dibasic acid anhydrides such as succinic anhydride, maleic anhydride, glutaric anhydride, itaconic anhydride, phthalic anhydride, and hexahydrophthalic anhydride; and the tetrabasic acid dianhydrides such as pyromellitic anhydride, biphenyltetracarboxylic dianhydride, and benzophenonetetracarboxylic dianhydride.

[0053] Examples of the caprolactone-modified polyfunctional (meth)acrylate include, for example, bisphenol A di(meth)acrylate modified with at least one selected from ethylene oxide and propylene oxide, isocyanuric acid tri(meth)acrylate modified with at least one selected from ethylene oxide and propylene oxide, trimethylolpropane tri(meth)acrylate modified with at least one selected from ethylene oxide and propylene oxide, and ethylene oxide. Examples of the modified acrylate include pentaerythritol tri(meth)acrylate modified with at least one selected from ethylene oxide and propylene oxide, pentaerythritol tetra(meth)acrylate modified with at least one selected from ethylene oxide and propylene oxide, dipentaerythritol penta(meth)acrylate modified with at least one selected from ethylene oxide and propylene oxide, and dipentaerythritol hexa(meth)acrylate modified with at least one selected from ethylene oxide and propylene oxide.

[0054] Examples of compounds having two or more N-alkoxymethylamino groups in the molecule include compounds having a melamine structure, a benzoguanamine structure, or a urea structure. Here, the term "melamine structure" refers to a chemical structure having one or more triazine rings as a basic skeleton, and the term "benzoguanamine structure" refers to a chemical structure having one or more phenyl-substituted triazine rings as a basic skeleton, and these concepts encompass melamine, benzoguanamine, and condensates thereof. Specific examples of compounds having two or more N-alkoxymethylamino groups in the molecule include N,N,N',N',N",N"-hexa(alkoxymethyl)melamine, N,N,N',N'-tetra(alkoxymethyl)benzoguanamine, and N,N,N',N'-tetra(alkoxymethyl)glycoluril.

[0055] Of the above, preferred polymerizable compounds in the present invention include polyfunctional (meth)acrylates obtained by reacting a trivalent or higher aliphatic polyhydroxy compound with (meth)acrylic acid, caprolactone-modified polyfunctional (meth)acrylates, polyfunctional urethane (meth)acrylates, polyfunctional (meth)acrylates having a carboxyl group, N,N,N',N',N",N"-hexa(alkoxymethyl)melamine, and N,N,N',N'-tetra(alkoxymethyl)benzoguanamine. Among the polyfunctional (meth)acrylates obtained by reacting a trivalent or higher aliphatic polyhydroxy compound, a (meth)acrylic, and an acid, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate are particularly preferred; and among the polyfunctional (meth)acrylates having a carboxyl group, a compound obtained by reacting pentaerythritol triacrylate with succinic anhydride and a compound obtained by reacting dipentaerythritol pentaacrylate with succinic anhydride are particularly preferred, in that the resulting curable resin compositions have high strength and excellent surface smoothness and are less likely to produce background smears, film residues, etc. on the substrate and light-shielding layer in unexposed areas.

[0056] <Binder Resin> The curable resin composition of the present invention may contain a binder resin. The presence of a binder resin can improve the alkali developability and storage stability of the curable resin composition. The binder resin is not particularly limited, but is preferably a resin having an acidic functional group such as a carboxyl group or a phenolic hydroxyl group. Among these, a polymer having a carboxyl group (hereinafter referred to as a "carboxyl group-containing polymer") is preferred, and examples thereof include copolymers of an ethylenically unsaturated monomer having one or more carboxyl groups (hereinafter referred to as an "unsaturated monomer (b1)") and another copolymerizable ethylenically unsaturated monomer (hereinafter referred to as an "unsaturated monomer (b2)").

[0057] Examples of the unsaturated monomer (b1) include (meth)acrylic acid, maleic acid, maleic anhydride, mono[2-(meth)acryloyloxyethyl] succinate, ω-carboxypolycaprolactone mono(meth)acrylate, and p-vinylbenzoic acid.

[0058] These unsaturated monomers (b1) can be used alone or in combination of two or more.

[0059] Examples of the unsaturated monomer (b2) include N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide; aromatic vinyl compounds such as styrene, α-methylstyrene, p-hydroxystyrene, p-hydroxy-α-methylstyrene, p-vinylbenzyl glycidyl ether, and acenaphthylene;

[0060] Methyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, allyl (meth)acrylate, benzyl (meth)acrylate, polyethylene glycol (degree of polymerization 2-10) methyl ether (meth)acrylate, polypropylene glycol (degree of polymerization 2-10) methyl ether (meth)acrylate, polyethylene glycol (degree of polymerization 2-10) mono(meth)acrylate, polypropylene glycol (degree of polymerization 2-10) mono(meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclo[5.2.1.0] 2,6 (meth)acrylic acid esters such as ]decan-8-yl (meth)acrylate, dicyclopentenyl (meth)acrylate, glycerol mono(meth)acrylate, 4-hydroxyphenyl (meth)acrylate, ethylene oxide-modified (meth)acrylate of para-cumylphenol, glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3-[(meth)acryloyloxymethyl]oxetane, and 3-[(meth)acryloyloxymethyl]-3-ethyloxetane;

[0061] Cyclohexyl vinyl ether, isobornyl vinyl ether, tricyclo[5.2.1.0 2,6 ] vinyl ethers such as decan-8-yl vinyl ether, pentacyclopentadecanyl vinyl ether, and 3-(vinyloxymethyl)-3-ethyloxetane; and macromonomers having a mono(meth)acryloyl group at the end of the polymer molecular chain, such as polystyrene, polymethyl(meth)acrylate, poly-n-butyl(meth)acrylate, and polysiloxane.

[0062] These unsaturated monomers (b2) can be used alone or in combination of two or more.

[0063] In the copolymer of the unsaturated monomer (b1) and the unsaturated monomer (b2), the copolymerization ratio of the unsaturated monomer (b1) in the copolymer is preferably 5 to 50 mass%, more preferably 10 to 40 mass%. By copolymerizing the unsaturated monomer (b1) in such a range, a colored composition excellent in alkali developability and storage stability can be obtained.

[0064] In the present invention, for example, a carboxyl group-containing polymer having a polymerizable unsaturated bond such as a (meth)acryloyl group in the side chain can also be used as the binder resin.

[0065] Furthermore, in the present invention, a copolymer of an unsaturated monomer containing a (meth)acrylic acid ester having an oxiranyl group, such as glycidyl (meth)acrylate, may be used, and the hydroxyl groups generated by the reaction of the copolymer with the unsaturated monomer (b1) may be further reacted with a polybasic acid anhydride to form a copolymer, which may be used as the binder resin.

[0066] Examples of such polybasic acid anhydrides include anhydrides of dibasic acids such as maleic anhydride, fumaric anhydride, citraconic anhydride, mesaconic anhydride, itaconic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, himic anhydride, phthalic anhydride, and naphthalene-2,3-dicarboxylic anhydride; monoanhydrides of tribasic or higher polybasic acids such as cyclohexane-1,2,4-tricarboxylic anhydride and trimellitic anhydride; and monoanhydrides of cyclohexane-1,2,4-tricarboxylic anhydride and trimellitic anhydride. Examples of suitable dianhydrides include dianhydrides of polybasic acids having tetrabasic or higher acids, such as hexanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, norbornanetetracarboxylic dianhydride, pyromellitic dianhydride, biphenyltetracarboxylic dianhydride, diphenylethertetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, and perylene-3,4,9,10-tetracarboxylic dianhydride.

[0067] The binder resin in the present invention has a weight average molecular weight (Mw) of typically 1,000 to 100,000, and preferably 3,000 to 50,000, in terms of polystyrene, as measured by GPC (elution solvent: tetrahydrofuran). By adopting such an embodiment, it becomes easier to form a coating film that is excellent in film retention, pattern shape, heat resistance, electrical properties, and resolution, and it is also possible to suppress the generation of dried foreign matter during application by a slit nozzle method.

[0068] The ratio (Mw / Mn) of the weight average molecular weight of the binder resin in the present invention to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC (elution solvent: tetrahydrofuran) is preferably 1.0 to 5.0, and more preferably 1.0 to 3.0.

[0069] In the present invention, the binder resins may be used alone or in combination of two or more.

[0070] In the present invention, the content of the binder resin is preferably 10 to 1,000 parts by mass, and particularly preferably 20 to 500 parts by mass, relative to 100 parts by mass of the colorant (A). By adopting such an embodiment, the alkali developability, the storage stability, and the chromaticity characteristics of the colored composition can be improved.

[0071] The curable resin composition according to the present invention is preferably a radiation-sensitive curable resin composition for forming a diffractive optical element.

[0072] <Photopolymerization initiator> The curable resin composition of the present invention can contain a photopolymerization initiator. This can impart radiation sensitivity to the curable resin composition, resulting in a radiation-sensitive curable resin composition. The photopolymerization initiator applicable to the present invention is a compound that generates an active species that can initiate polymerization of a polymerizable compound when exposed to radiation such as visible light, ultraviolet light, far ultraviolet light, electron beams, or X-rays.

[0073] Examples of such photopolymerization initiators include thioxanthone-based compounds, acetophenone-based compounds, biimidazole-based compounds, triazine-based compounds, O-acyloxime-based compounds, onium salt-based compounds, benzoin-based compounds, benzophenone-based compounds, α-diketone-based compounds, polynuclear quinone-based compounds, diazo-based compounds, imidosulfonate-based compounds, and onium salt-based compounds.

[0074] In the present invention, the photopolymerization initiator may be used alone or in combination of two or more. The photopolymerization initiator is preferably at least one selected from the group consisting of thioxanthone compounds, acetophenone compounds, biimidazole compounds, triazine compounds, and O-acyloxime compounds.

[0075] Among the preferable photopolymerization initiators in the present invention, specific examples of the thioxanthone-based compounds include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone.

[0076] Specific examples of the acetophenone-based compound include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, and 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one.

[0077] Specific examples of the biimidazole-based compound include 2,2'-bis(2-chlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole, and 2,2'-bis(2,4,6-trichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole.

[0078] When a biimidazole compound is used as a photopolymerization initiator, it is preferable to use a hydrogen donor in combination, as this can improve sensitivity. The term "hydrogen donor" as used herein refers to a compound capable of donating a hydrogen atom to a radical generated from the biimidazole compound upon exposure. Examples of hydrogen donors include mercaptan hydrogen donors such as 2-mercaptobenzothiazole and 2-mercaptobenzoxazole, and amine hydrogen donors such as 4,4'-bis(dimethylamino)benzophenone and 4,4'-bis(diethylamino)benzophenone. In the present invention, the hydrogen donors can be used alone or in combination of two or more. However, it is preferable to use a combination of one or more mercaptan hydrogen donors and one or more amine hydrogen donors, as this can further improve sensitivity.

[0079] Specific examples of the triazine compounds include 2,4,6-tris(trichloromethyl)-s-triazine, 2-methyl-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(5-methylfuran-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(furan-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(furan-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, and 2-[2-(4-diethylamino-2-methylphenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine.

[0033] Examples of triazine compounds having a halomethyl group include 2-[2-(3,4-dimethoxyphenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-ethoxystyryl)-4,6-bis(trichloromethyl)-s-triazine, and 2-(4-n-butoxyphenyl)-4,6-bis(trichloromethyl)-s-triazine.

[0080] Specific examples of the O-acyloxime compound include 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(O-benzoyloxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime), ethanone, 1-[9-ethyl-6-(2-methyl-4-tetrahydrofuranylmethoxybenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime), ethanone, 1-[9-ethyl-6-{2-methyl-4-(2,2-dimethyl-1,3-dioxolanyl)methoxybenzoyl}-9H-carbazol-3-yl]-, 1-(O-acetyloxime), and the like.

[0081] In the present invention, when a photopolymerization initiator other than a biimidazole compound, such as an acetophenone compound, is used, a sensitizer can also be used in combination. Examples of such sensitizers include 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4-diethylaminoacetophenone, 4-dimethylaminopropiophenone, ethyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,5-bis(4-diethylaminobenzal)cyclohexanone, 7-diethylamino-3-(4-diethylaminobenzoyl)coumarin, and 4-(diethylamino)chalcone.

[0082] In the present invention, the content of the photopolymerization initiator in the curable resin composition is preferably 0.01 to 120 parts by mass, and particularly preferably 1 to 100 parts by mass, per 100 parts by mass of the polymerizable compound (C). By adopting such an embodiment, the curability and coating properties become good.

[0083] The curable resin composition has a minimum transmittance of 50% or less for normally incident light with a wavelength of 410 nm to 1100 nm when applied uniformly to a thickness of 1 μm. When the curable resin composition has the above characteristics and a minimum transmittance of 50% or less for light with a wavelength of 410 nm to 1100 nm, it becomes possible to form a light-shielding region for wavelengths of 410 nm to 1100 nm, and the resulting diffractive optical element can be optimally used for diffractive optical lenses for imaging, optical lenses for optical sensors, optical lenses for displays, and optical lenses for optical communication.

[0084] The minimum transmittance for light with a wavelength of 410 nm to 1100 nm is preferably 30% or less, more preferably 15% or less, even more preferably 10% or less, and particularly preferably 5% or less.

[0085] When the curable resin composition is applied uniformly to a thickness of 1 μm, the maximum extinction coefficient for light having a wavelength of 410 nm to 1,100 nm is 0.0001 or more and 1.1 or less. When the maximum extinction coefficient for light having a wavelength of 410 nm to 1,100 nm is 0.001 or more and 1.1 or less, it becomes possible to form a light-shielding region for wavelengths of 410 nm to 1,100 nm, and the resulting diffractive optical element is optimally usable for imaging diffractive optical lenses, optical lenses for optical sensors, optical lenses for displays, and optical lenses for optical communications. Furthermore, when the colorant concentration satisfies the above maximum extinction coefficient, it becomes easy to achieve a refractive index of 1.6 or more at any wavelength in the wavelength range of 410 nm to 1,100 nm, which is preferable for improving the performance of the diffractive optical element.

[0086] The maximum extinction coefficient for light with a wavelength of 410 nm to 1,100 nm is preferably in the range of 0.005 to 1.1, more preferably in the range of 0.01 to 1.0, and even more preferably in the range of 0.05 to 0.9. From the viewpoint of forming a diffractive optical element with sufficient light-blocking ability and suppressing interface reflection due to differences in extinction coefficients, i.e., suppressing stray light, it is preferable that the maximum extinction coefficient be within the above-mentioned range. Furthermore, from the viewpoint of being able to appropriately adjust the absorber concentration and suppress the occurrence of agglomerated foreign matter, and being able to form a fine diffractive optical element, it is preferable that the maximum extinction coefficient be set to not more than the upper limit of the above-mentioned range. Note that, in this specification, the expression "within the range of A to B" is synonymous with "not less than A and not more than B."

[0087] When the curable resin composition is applied uniformly to a thickness of 1 μm, the maximum transmittance for perpendicularly incident light with a wavelength of 410 nm to 1,100 nm is 50% or more. When the curable resin composition has the above-mentioned characteristics, the maximum transmittance for ... light-shielding resin layer is formed, it is possible to form transparent regions at different wavelengths in the wavelength range of 410 nm to 1,100 nm. The resulting diffractive optical element enables wavelength-selective control of optical properties in diffractive optical lenses for imaging, optical lenses for optical sensors, optical lenses for displays, and optical lenses for optical communication.

[0088] The maximum transmittance for light with a wavelength of 410 nm to 1,100 nm is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 85% or more.

[0089] The dielectric multilayer film according to the present invention is composed of, for example, a multilayer structure in which high-refractive index layers and low-refractive index layers are alternately stacked. The dielectric multilayer film may have a medium-refractive index layer between the high-refractive index layers and the low-refractive index layers.

[0090] The high refractive index layer has a refractive index of n H Then, the refractive index n H is preferably 2.0 or more. As the high refractive index layer, for example, a film containing titanium oxide (TiO2), tantalum oxide (Ta2O5), niobium oxide (Nb2O5), or a composite oxide thereof may be used. Furthermore, as long as the refractive index is 2.0 or more, an additive may be contained. H A higher refractive index is advantageous for suppressing the amount of wavelength shift at the time of oblique incidence, widening the light transmission blocking band on the ultraviolet side, etc. Therefore, among the above, titanium oxide and niobium oxide, which have higher refractive index, are more suitable for the high refractive index layer.

[0091] The low refractive index layer has a refractive index of n L Then, the refractive index n L is preferably less than 1.6, and more preferably lower than the refractive index of the outermost layer of the transparent substrate. The low refractive index layer may be, for example, a film containing silicon oxide (SiO2), magnesium fluoride (MgF2), barium fluoride (BaF2), lithium fluoride (LiF), or a composite oxide thereof. The low refractive index layer may also be, for example, a film containing silicon oxide (SiO2), magnesium fluoride (MgF2), barium fluoride (BaF2), lithium fluoride (LiF), or a composite oxide thereof. L The film may contain an additive as long as the refractive index is 1.7 or less or lower than the refractive index of the outermost layer of the transparent substrate.

[0092] The medium refractive index layer has a refractive index of n M Then, the refractive index n MThe refractive index of the intermediate refractive index layer is preferably 1.6 or more and less than 2.0, and more preferably lower than the refractive index of the outermost layer of the transparent substrate. For example, a film containing aluminum oxide (Al2O3), cesium fluoride (CeF3), yttrium oxide (YO3), ytterbium oxide (Yb2O3), or a composite oxide thereof can be used as the intermediate refractive index layer. M If the value is 1.6 or more and less than 2.0, additives may be contained.

[0093] Dielectric layers such as high-, medium-, and low-refractive-index layers are formed using, for example, sputtering, vacuum deposition, ion-assisted vacuum deposition, and CVD. Sputtering, vacuum deposition, and ion-assisted vacuum deposition are particularly preferred. The light transmission band is the wavelength band used for receiving light in solid-state imaging devices such as CCD image sensors and CMOS image sensors, making the thickness accuracy of the dielectric layer important. Sputtering, vacuum deposition, and ion-assisted vacuum deposition are excellent at controlling the thickness when forming the dielectric layer. This allows for increased thickness accuracy for each layer constituting the dielectric multilayer film, which is composed of a stack of dielectric layers, resulting in a dielectric multilayer film with desired optical properties. Among these, ion-assisted vacuum deposition is more preferred for achieving both improved film formation speed and control of film thickness.

[0094] The dielectric multilayer film may be preferably provided on both sides of a transparent substrate, which is expected to improve the visible light transmittance by reducing the reflection in the visible light region on both sides of the substrate, and is also suitable for reducing warpage.

[0095] <Light-Shielding Resin Layer> The light-shielding resin layer is a resin layer formed from a material containing a curable resin composition and exhibiting light-shielding properties for light in the wavelength range of 410 nm to 1,100 nm. The diffractive optical element of the present invention has a light-shielding resin layer that forms a diffraction pattern, and the maximum width of the thinnest light-shielding resin layer is preferably 2.0 μm or less. The thinnest light-shielding resin layer of the present invention refers to the light-shielding resin layer with the smallest width, defined as the distance from a transparent region not having a light-shielding resin layer to another transparent region diagonally opposite the light-shielding resin layer when the optical element is observed from directly above. The maximum width of the thinnest light-shielding resin layer is more preferably 1.8 μm or less, even more preferably 1.5 μm or less, and particularly preferably 1.2 μm or less. Furthermore, in order to achieve diffractive properties, the lower limit of the width of the thinnest structure is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.25 μm or more. The width of the narrowest structure in the light-shielding resin layer can be outside the above-mentioned range, but from the viewpoint of further increasing the diffraction efficiency, it is preferable to set it within the above-mentioned range.

[0096] From the viewpoint of further increasing the efficiency of the amount of light collected, the light-shielding resin layer has an average thickness of preferably 2 μm or less, more preferably 1.8 μm or less, even more preferably 1.5 μm or less, particularly preferably 1.0 μm or less, and even more preferably 0.8 μm or less.

[0097] <Fresnel Zone Plate> A Fresnel zone plate (FZP) is a type of diffractive optical element having a diffractive optical structure with a concentric pattern in which light-shielding (opaque) zones (zones) formed by a light-shielding resin layer made of a curable resin composition and transparent zones (zones) where the main surface of the substrate is exposed are alternately combined. The concentric pattern of the Fresnel zone plate has a shape as shown in Figure 1, and the radius r of the nth zone is n is expressed by the following formula (1).

[0098]

[0099] In this specification, a pattern shape that satisfies the above formula (1) is called a "Fresnel zone plate shape." In the above formula (1), λ is the wavelength of light, and f is the focal length of first-order diffraction. A design in which the center starts from light blocking and a design in which the center starts from transmission are possible. For example, in the case of a design in which the center starts from light blocking, r n 2 The zone between n=0 and n=1 is opaque, the zone between n=1 and n=2 is transparent, the zone between n=2 and n=3 is opaque, and so on, alternating between transparent and opaque depending on whether n is odd or even.

[0100] When light having a wavelength λ in the range of 410 nm to 1,100 nm is incident as a parallel beam from a direction perpendicular to the main surface of the substrate, and the focal length f is the distance between the substrate and the focusing position D of the light of wavelength λ, the focal length f is preferably 2 μm or more and 70 cm or less. From the viewpoint of focusing more light from the outer periphery of the optical element and increasing the focusing efficiency at the focusing position D, the lower limit of the focal length f of first-order diffraction is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. From the viewpoint of suppressing a decrease in light utilization efficiency due to light diffusion, the upper limit of the focal length f of first-order diffraction is preferably 80 cm or less, more preferably 50 cm or less, even more preferably 45 cm or less, and particularly preferably 30 cm or less.

[0101] Here, it is preferable that the diffractive optical element has more than 20 boundaries in one direction where the light-shielding region transitions to the light-transmitting region. Here, the number of light-shielding regions is determined by the number of boundaries between the diagonal line (r d1 , r d2 ) on two or more diagonals (r d1 , r d2 ) intersection point C o and the center C o Count the light-shielding areas in any direction from the outer periphery, and calculate the boundaries (d1, d2, ..., d n ) is the maximum number of boundaries. As shown in FIGS. 2A and 2B, the diffractive optical element 1 has 14 boundaries (d1, d2, ..., d14 ), that is, the diffractive optical element has resin layers 20 formed on 14 concentric circles. The number of light-shielding regions (resin layers) that the diffractive optical element has is preferably more than 59, more preferably more than 150, even more preferably more than 300, and particularly preferably more than 800. If the number of light-shielding regions is within the above-mentioned range, higher light-collecting performance is exhibited, and therefore the diffractive optical element 1 that is suitable for a fine imaging element can be realized.

[0102] The F-number is a value obtained by irradiating light of a wavelength λ within a wavelength range of 410 nm to 1,100 nm as a parallel ray T from a direction perpendicular to the main surface 10a of the substrate 10 (a direction parallel to the optical axis Ax) as shown in FIG. 2C. L When the focal length f is the distance between the focal position D of light of wavelength λ incident on the substrate 10 and the substrate 10, the focal length f is calculated by dividing the focal length f by the diameter of the circumscribing circle of the diffraction pattern when viewed in a direction perpendicular to the major surface 10a of the substrate 10 (FIG. 1), and is preferably within the range of 0.2 to 4.0. The range of the F-number is not particularly limited, but if it is 0.2 or greater, it is easy to form and maintain a microstructure that exhibits a diffractive effect. The lower limit of the F-number is preferably 0.3 or greater, and more preferably 0.4 or greater. Furthermore, if the F-number is equal to or less than the above-mentioned upper limit, it is easier to ensure a sufficient amount of light for imaging. Considering the limitations on applications due to the shape and size of the entire optical module and the significant influence of aberrations that make it difficult to focus light on the entire sensor surface, the upper limit of the F-number is preferably 3.5 or less, more preferably 3.2 or less, and even more preferably 3.0 or less.

[0103] As shown in Fig. 3, Fresnel zone plate shapes of different designs may be combined in the radial direction, and each of them may be formed from a different curable resin composition.

[0104] <Linear Zone Plate> A linear zone plate is a plate that is formed by dividing the r n Instead of the line length L from the center to the periphery nIt is a linear diffractive optical structure with a linear zone plate. Figure 4 shows an example of a linear zone plate observed from above. It has the property of focusing light in any area on the center line, making it suitable for high-definition optical sensor applications. Like Fresnel zone plates, the center can function either as a light-shielding or transparent structure. Like Fresnel zone plates, it may have a structure that combines linear zone plates of multiple designs, some of which have different focal lengths and some of which have different curable resin compositions. It may also be decentered, or linear zone plates of multiple designs may be stacked.

[0105] In this specification, a pattern shape having the above-mentioned characteristics is referred to as a "linear zone plate shape."

[0106] <Fractal Zone Plate> A fractal zone plate, like the Fresnel zone plate, is a type of diffractive optical element with a diffractive optical structure consisting of a concentric pattern of alternating light-shielding and transparent rings (zones). Like the Fresnel zone plate, a fractal zone plate is formed by dividing the light-shielding and transparent regions according to the above formula (1), and then connecting the light-shielding regions using a Cantor set. As shown in FIG. 5, a Cantor set is expressed by the number of divisions Nc and the number of divisions S. If the central region of the element is number 1 and the outermost light-shielding region is number N, these light-shielding regions are divided equally into (2Nc+1). Then, both ends are transparent regions, and the center is a light-shielding region. That is, the first through ((N / 3)-1) regions are transparent regions, the (N / 3) through ((2N / 3)-1) regions are light-shielding regions, and the (2N / 3) through N regions are light-shielding regions. When S is 2 or greater (S n = S2, S3, ...), the transparent region is again divided into (2Nc+1) equal parts, and then the process of making both ends transparent and the center a light-shielding region is repeated (n-1) times. In other words, a fractal zone plate is a diffractive optical element in which the alternating divisions of light-shielding and transparent regions in a Fresnel zone plate are converted into light-shielding and transparent regions that form a Cantor set. Figure 6 shows an example of a fractal zone plate observed from a direction perpendicular to the main surface of the substrate.

[0107] In this specification, a pattern shape having the above characteristics is referred to as a "fractal zone plate shape."

[0108] <Photon Sieve Plate> A photon sieve plate has a structure in which pinholes are arranged instead of the transparent zones of a Fresnel zone plate. Since the light-shielding area is continuous, it is expected to be extracted as a free-standing film, which is preferable when using a thin film substrate. The position R from the center of the pinhole n is calculated by the following formula (2).

[0109]

[0110] nth pinhole radius r pn is r pn = fλ / (4 × R n ) and the number of n-th pinholes N hole is calculated by the following formula (3).

[0111]

[0112] N ring、 is the number of rings consisting of pinholes arranged concentrically in the photon sieve plate. ring When reflected in an actual design, the decimal points are rounded up, down, or up to the nearest integer, and the shape shown in Figure 7 is an example of the shape of a photon sieve plate when observed from the vertical direction.

[0113] In this specification, the shape of the pattern having the above characteristics is referred to as a "photon sieve plate shape."

[0114] <Refractive Index and Extinction Coefficient> The refractive index n and extinction coefficient k of the curable resin were measured by applying a sample to a thickness of 1 μm to a silicon wafer (111 orientation, undoped, diameter 10 mm, thickness 280 μm, manufactured by Universalwafer Inc.) using a spinner, and measuring the refractive index n and extinction coefficient k using a spectroscopic ellipsometry (M-2000D manufactured by J.A. Woollam).

[0115] The evaluation of the maximum absorption wavelength, the evaluation of the maximum transmittance, and the evaluation of the minimum transmittance were calculated by measuring the transmittance in each wavelength range using a 1 μm-thick sample for which the wavelength-specific refractive index and extinction coefficient were measured. The transmittance at each wavelength was measured using a spectrophotometer (U-4100) manufactured by Hitachi High-Technologies Corporation, after leaving the sample to stand for one week in a dark environment at room temperature of 25° C. and humidity of 60%, using unpolarized light incident from a direction perpendicular to the substrate of the diffractive optical element, under an environment at room temperature of 25° C. and humidity of 50%.

[0116] [Curable resin composition 1: JSSG-9135 manufactured by JSR Corporation] The refractive index and extinction coefficient of curable resin composition 1 by wavelength are shown in Figure 8. Within the wavelength range of 410 nm to 1,100 nm, curable resin composition 1 had maximum absorptance for light with wavelengths of 483 nm, 659 nm, and 738 nm, with a maximum transmittance of 86% and a minimum transmittance of 0.5%.

[0117] [Curable resin composition 2: BLUE-105 manufactured by JSR Corporation] The refractive index and extinction coefficient of curable resin composition 2 by wavelength are shown in Fig. 9. Within the wavelength range of 410 nm to 1,100 nm, curable resin composition 2 had maximum absorptance for light with wavelengths of 620 nm and 756 nm, with a maximum transmittance of 65% and a minimum transmittance of 1.5%.

[0118] [Curable resin composition 3: RED-101 manufactured by JSR Corporation] The refractive index and extinction coefficient of curable resin composition 3 by wavelength are shown in Fig. 10. Within the wavelength range of 410 nm to 1,100 nm, curable resin composition 3 had maximum absorptance for light with wavelengths of 530 nm and 578 nm, with a maximum transmittance of 88% and a minimum transmittance of 5%.

[0119] [Curable Resin Composition 4: Positive i-Line Resist (IX420H manufactured by JSR)] For Curable Resin Composition 4, a simulation was performed with a refractive index of 1.5 and an extinction coefficient of 0.

[0120] [Curable Resin Composition 5] Curable resin composition 5 was prepared by mixing 0.083 g of FDB-004 (manufactured by Yamada Chemical Industry Co., Ltd.), 0.017 g of pentaerythritol tetraacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.6 mg of IRGACURE 184 (manufactured by Ciba Japan Co., Ltd.), 0.6 mg of octamethylcyclotetrasiloxane (manufactured by Tokyo Chemical Industry Co., Ltd.), 1 g of cyclopentanone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.05 g of propylene glycol 1-monomethyl ether 2-acetate (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0121] The extinction coefficient of curable resin composition 5 was as shown in Figure 11. The coating film of curable resin composition 5 contained a large amount of aggregates due to the high concentration of dye, making it difficult to stably calculate the refractive index. Furthermore, the amount of aggregates contained in the coating film of curable resin composition 5 was so large that it was not suitable for microfabrication even after ultraviolet irradiation. Note that curable resin composition 5 had a maximum absorption wavelength of 449 nm and an extinction coefficient of 1.1. Furthermore, the maximum transmittance was 89% and the minimum transmittance was 0.0%.

[0122] Example 1 An adhesion promoter (Dow Chemical AP3000) was applied to a quartz glass substrate (manufactured by Electronics and Materials Corporation, diameter 100 mm, thickness 0.525 mm) using a spinner, and then heated on a hot plate at 190°C for 300 seconds to form an adhesion promoter layer. Onto the quartz glass substrate with this adhesion promoter layer, curable resin composition 2 (JSR Corporation, Blue-105A) was applied using a spinner, and then prebaked on a hot plate at 100°C for 180 seconds to form a substrate with a coating film. The substrate with this coating film was exposed to 405 nm light using a maskless lithography device (HEIDELBERG INSTRUMENTS DWL66+). The shape to be exposed was set to a radius of 1.84 mm (F-number 1.36) derived from the above formula (1) where the focal length f=5 mm, the wavelength λ=550 nm, and n=1181.

[0123] After the exposure, the plate was immersed in a resist developer (S-170809 manufactured by Kanto Chemical Co., Inc.) to dissolve the unexposed portions. After rinsing the resist developer with pure water, the plate was air-dried with an air gun and post-baked on a hot plate at 200°C for 300 seconds to obtain a Fresnel zone plate having 590 light-shielding resin layers with a thickness of 0.7 µm. To evaluate the optical properties of the obtained Fresnel zone plate, the light-collecting characteristics at a wavelength of 550 nm were evaluated using the following optical element.

[0124] Laser light source: PHAROS (PH1-SP-1mJ), manufactured by LightConversion Wavelength converter: ORPHEUS, manufactured by LightConversion Beam profiler: IMX219PQ, manufactured by Sony Corporation The light intensity distribution in the x direction at the focusing position obtained from the beam profiler is shown in Figure 12. The FWHM was 1.8 μm, and the focusing characteristics were sufficient for imaging.

[0125] Example 2 An adhesion promoter (Dow Chemical AP3000) was applied to a quartz glass substrate (manufactured by Electronics and Materials Corporation, diameter 100 mm, thickness 0.525 mm) using a spinner, and then heated on a hot plate at 190°C for 300 seconds to form an adhesion promoter layer. A curable resin composition 2 (manufactured by JSR Corporation, Blue-105A) was applied to the quartz glass substrate with this adhesion promoter layer using a spinner, and then pre-baked on a hot plate at 100°C for 180 seconds to form a substrate with a coating film. The substrate with this coating film was scanned using an i-line stepper (Canon Inc., FPA-3030i5+) to a radius of 1.84 mm (F-number 1.36), calculated from the above formula (1) using a focal length f = 5 mm, a wavelength λ = 550 nm, and n = 1181.

[0126] After the exposure, the unexposed portions were dissolved by immersion in a resist developer (S-170809 manufactured by Kanto Chemical Co., Ltd.) The resist developer was washed away with pure water, and the plate was air-dried with an air gun and then post-baked on a hot plate at 200°C for 300 seconds to obtain a Fresnel zone plate having 590 light-shielding resin layers with a thickness of 0.495 µm.

[0127] To evaluate the optical properties of the obtained Fresnel zone plate, the light-condensing property at a wavelength of 550 nm was evaluated using the following optical element.

[0128] Laser light source: PHAROS (PH1-SP-1mJ), manufactured by LightConversion Wavelength converter: ORPHEUS, manufactured by LightConversion Objective lens: PLN40X, manufactured by Olympus Corporation Beam profiler: DCC1545M, manufactured by Thorlabs The light intensity distribution at the focusing position obtained by the beam profiler is shown in Figure 13. The FWHM was 1.1 μm, and the focusing characteristics were sufficient for imaging.

[0129] Furthermore, when the obtained Fresnel zone plate was used to capture images of USAF1951, the images shown in Figures 14A, 14B, and 14C were obtained. This proves that the lens is suitable for capturing images with a resolving power of Group 8 or higher.

[0130] Example 3 An adhesion promoter (AP3000 manufactured by The Dow Chemical Company) was applied to a glass substrate (Corning Incorporated, Eagle XG, diameter 8 inches, thickness 0.7 mm) using a spinner, and then heated on a hot plate at 190°C for 300 seconds to form an adhesion promoter layer. Onto the quartz glass substrate with this adhesion promoter layer, curable resin composition 1 (JSSG-9135 manufactured by JSR Corporation) was applied using a spinner, and then pre-baked on a hot plate at 100°C for 180 seconds to form a substrate with a coating film. The substrate with this coating film was exposed to light using an i-line stepper (Canon Inc., FPA-3030i5+) to the pattern shape (Fresnel zone plate shape) shown in Figures 2A and 2B, which had a radius of 11 mm and a narrowest width of 0.8 μm (F-number 1.36), calculated using the focal length f = 30 mm, wavelength λ = 550 nm, and n = 7089 in equation (1) above. After exposure, the substrate was immersed in a resist developer (Kanto Chemical Co., Inc., S-170809) to dissolve the unexposed portions. After rinsing the resist developer with pure water, the substrate was air-dried with an air gun and post-baked on a hot plate at 200°C for 300 seconds, yielding a Fresnel zone plate with 3,545 light-shielding regions.

[0131] As shown in Figure 15A, after removing the attached lens from a camera (Canon EOS Kiss X5, sensor size 22.3 mm × 14.9 mm, pixel count 5184 × 3456), the obtained Fresnel zone plate was set at a position 50 mm away from the sensor. When an image of a subject placed at a position 75 mm from the surface of the Fresnel zone plate was captured, an image of the subject was obtained as shown in Figure 15B, confirming that the Fresnel zone plate was functioning as a lens.

[0132] Example 4 An adhesion promoter (Dow Chemical Company AP3000) was applied to a glass substrate (Corning Incorporated, Eagle XG, diameter 8 inches, thickness 0.7 mm) using a spinner, and then heated on a hot plate at 190°C for 300 seconds to form an adhesion promoter layer. Onto the quartz glass substrate with this adhesion promoter layer, curable resin composition 1 (JSR Corporation, JSSG-9135) was applied using a spinner, and then pre-baked on a hot plate at 100°C for 180 seconds to form a substrate with a coating film. The substrate with this coating film was exposed to light using an i-line stepper (Canon Inc., FPA-3030i5+) to form a Fresnel zone plate shape with a radius of 2.9 mm and a narrowest width of 0.8 μm (F-number 1.71), calculated using the formula (1) with a focal length f of 10 mm, a wavelength λ of 450 nm, and n = 1871. After the exposure, the unexposed portions were dissolved by immersion in a resist developer (S-170809 manufactured by Kanto Chemical Co., Ltd.) After rinsing the resist developer with pure water, the plate was air-dried with an air gun and post-baked on a hot plate at 200°C for 300 seconds to obtain a Fresnel zone plate consisting of 936 light-shielding regions.

[0133] Furthermore, when the obtained Fresnel zone plate was used to image USAF1951 in the same manner as in Example 2, it was found that the lens had sufficient performance for imaging.

[0134] Example 5 Into electromagnetic field calculation simulation software (Ansys Lumerical, manufactured by Ansys), the thickness direction of the light-shielding resin layer (the optical axis direction of the diffractive optical element) was defined as the z direction, and on an xy plane perpendicular to the z direction, a light-shielding resin layer with a radius of 0.045 mm, a thickness of 0.5 μm, a focal length f = 0.05 mm in Formula A, a wavelength λ = 550 nm, and a Fresnel zone plate-shaped diffraction pattern with the center being transparent was input. The number of light-shielding resin layers was 31, and the finest line width was 0.4 μm (F value 0.56). The material of the light-shielding resin layer was curable resin composition 1, and a curable resin composition 1 with a radius of 0.25 mm and a thickness of 0.5 μm was uniformly provided on the -z side of the curable resin composition 1. SiO2 with a radius of 0.25 mm and a thickness of 0.65 mm was provided underneath. For this model, the electric field intensity (Field) in the xy plane at a position 0.045 mm from the upper surface of the Fresnel zone plate was calculated by the FDTD method under the following conditions.

[0135] (Calculation conditions) Fresnel zone plate installation position: x direction: -0.045mm to 0.045mm y direction: -0.045mm to 0.045mm z direction: 0μm to 0.5μm FDTD calculation area: x direction: -0.045mm to 0.045mm y direction: -0.045mm to 0.045mm z direction: -1.0μm to 60μm Mesh size: 0.1μm in x, y, and z Light source settings: Wavelength 550nm Light source incident position: The light source surface is at -0.5μm in the z direction, and it is emitted in the positive z direction Light source distribution: Plane wave

[0136] The obtained electric field strength |E| in the x direction at y = 0 2 (V 2 / m 2 ) gave the results shown in Figure 16. The full width at half maximum (FWHM), which represents the light-collecting performance calculated by Gaussian distribution fitting of the obtained figure, was 0.4 µm, and the lens had high light-collecting performance suitable for imaging applications.

[0137] Example 6 A light-shielding resin layer with a radius of 0.25 mm, a thickness in the +z direction of 1 μm, a focal length f of 0.5 mm, a wavelength λ of 650 nm, Nc = 2, and S = 4 on an xy plane perpendicular to the z direction, with the thickness direction of the light-shielding resin layer (the optical axis direction of the diffractive optical element) defined as the z direction, and a diffraction pattern in the shape of a fractal zone plate was input into electromagnetic field calculation simulation software (Ansys Lumerical, manufactured by Ansys). The number of light-shielding resin layers was 15, and the finest line width was 0.8 μm (F-number 1.0). The material constituting the light-shielding resin layer was curable resin composition 2, and a SiO layer with a radius of 0.25 mm and a thickness of 0.65 mm was provided below the curable resin composition 2, closer to the light source. For this model, the light source incident position: the xy plane position of z coordinate -1.2 μm was set as the light source surface, and the light was emitted in the +z direction. Except for the calculation range being changed to match the radius and thickness of the fractal zone plate, the electric field strength (Field) in the x direction, y = 0, at the focal position, z = 0.1 mm, was calculated using the FDTD method and Far Field calculation in the same manner as in Example 5. The obtained electric field strength |E| 2 (V 2 / m 2 ) is shown in Figure 17. The FWHM in the x direction was 0.8 μm, and the light-collecting performance was sufficiently high for application to imaging.

[0138] Example 7 In electromagnetic field calculation simulation software (Ansys Lumerical manufactured by Ansys), the thickness direction of the light-shielding resin layer (the optical axis direction of the diffractive optical element) is defined as the z direction, and on the xy plane where z = 0 orthogonal to the z direction, the radius is 0.04 mm, the thickness in the +z direction is 0.7 μm, and the focal length in the above formula (2) is 0.1 mm, and the wavelength λ is 550 nm, the position from the center of the pinhole is calculated, and then the maximum N ringA light-shielding resin layer having a diffraction pattern with a pinhole having a pinhole radius of 12 and a photon sieve shape was input. The number of light-shielding regions was 12, and the finest line width was 0.1 μm (F value 1.25). The material constituting the light-shielding resin layer was curable resin composition 2, and a SiO2 layer with a radius of 0.25 mm and a thickness of 0.65 mm was provided on the side of the curable resin composition 2 closer to the light source. For this model, the light source incident position: the xy plane position of z coordinate -1.5 μm was used as the light source surface, and emission was in the +z direction. The electric field intensity (Field) of the xy plane at the focal position z = 0.1 mm was calculated using the FDTD method and Far Field calculation in the same manner as in Example 5, except that the calculation range was changed to match the radius and thickness of the photon sieve shape. The obtained electric field intensity |E| 2 (V 2 / m 2 ) is shown in Figure 18. The FWHM in the x direction was 0.9 μm, which was a sufficiently high light-collecting performance suitable for imaging applications.

[0139] Example 8 In an electromagnetic field calculation simulation software (Ansys Lumerical manufactured by Ansys), the thickness direction of the light-shielding resin layer (optical axis direction of the diffractive optical element) is defined as the z direction, the x direction, which is one direction on the xy plane perpendicular to the z direction, is defined as the line segment length, and the y direction, which is perpendicular to the x direction and z direction, is defined as the width. The thickness is 1 μm, and the focal length in the above formula (1) is 0.5 mm, the wavelength λ is 450 nm, and the radius r n Instead of the line length L n A light-shielding resin layer with a diffraction pattern of a linear zone plate shape with a width of 0.05 mm was input. The number of light-shielding regions was 100, and the finest line width was 0.8 μm (F value 1.14). The material of the light-shielding resin layer was curable resin composition 3, and a SiO2 layer with a line segment length of 0.22 mm and a thickness of 0.65 mm was provided on the -z side of curable resin composition 3. For this model, the electric field strength (Field) in the x direction at z = 0.5 mm, y = 0 was calculated using the FDTD method and Far Field calculation in the same manner as in Example 5, except that the calculation range was changed to match the line segment length, width, and thickness of the linear zone plate shape. The obtained electric field strength |E| 2 (V 2 / m 2) is shown in Figure 19. The FWHM in the x direction at the position of z = 0.5 mm was 0.5 µm, which was a sufficiently high light-collecting performance suitable for imaging applications.

[0140] Example 9 A light-shielding resin layer with a radius of 0.24 mm, a thickness of 1 μm, a focal length f of 1 mm in the above formula (1), and a wavelength λ of 940 nm on an xy plane perpendicular to the z direction, was input into electromagnetic field calculation simulation software (Ansys Lumerical, manufactured by Ansys). The diffraction pattern was a Fresnel zone plate shape. The number of light-shielding regions was 30, and the finest line width was 2 μm (F value: 2.08). The material of the light-shielding resin layer was curable resin composition 2, and a SiO layer with a radius of 0.25 mm and a thickness of 0.65 mm was provided on the -z side of curable resin composition 2. For this model, the calculation range was changed to match the radius and thickness of the Fresnel zone plate shape, and the wavelength λ was changed to 940 nm. In the same manner as in Example 5, the electric field intensity (Field) in the xz plane at y = 0 was calculated using the FDTD method and Far Field calculation. The obtained electric field intensity |E| 2 (V 2 / m 2 ) is shown in Figure 20. The FWHM in the x direction at y = 0, the z direction position where the electric field strength is maximum, was 1 µm, and the light-collecting performance was sufficiently high for application to imaging.

[0141] Example 10: Into electromagnetic field calculation simulation software (Ansys Lumerical, manufactured by Ansys), the thickness direction of the light-shielding resin layer (the optical axis direction of the diffractive optical element) was defined as the z direction, and on the xy plane perpendicular to the z direction, a light-shielding resin layer with a radius of 17.5 μm, a thickness of 1.4 μm, and a diffraction pattern in the shape of a Fresnel zone plate with the focal length f = 2.5 μm and wavelength λ = 450 nm in the above formula (1) was input. The number of light-shielding regions was 30, and the finest line width was 0.27 μm (F value 0.07). The material of the light-shielding resin layer was curable resin composition 2, and a SiO layer with a radius of 17.5 μm and a thickness of 50 μm was provided on the -z side of the curable resin composition 2. For this model, the calculation range was changed to match the radius and thickness of the Fresnel zone plate shape, and the wavelength λ was changed to 530 nm. Except for this, the electric field intensity (Field) in the xz plane at y = 0 was calculated by the FDTD method in the same manner as in Example 5. The obtained electric field intensity |E| 2 (V 2 / m 2 ) is shown in Figure 21. The FWHM in the x direction at y = 0, the z direction position where the electric field strength is maximum, was 0.5 µm, and the light-collecting performance was sufficiently high for application to imaging.

[0142] Example 11: Into electromagnetic field calculation simulation software (Ansys Lumerical, manufactured by Ansys), the thickness direction of the light-shielding resin layer (the optical axis direction of the diffractive optical element) was defined as the z direction, and on an xy plane perpendicular to the z direction, a light-shielding resin layer with a radius of 18 μm, a thickness of 2.1 μm, and a diffraction pattern in the shape of a Fresnel zone plate with a focal length f = 1.9 μm and a wavelength λ = 530 nm in the above formula (1) was input. The number of light-shielding regions was 30, and the finest line width was 0.27 μm (F value 0.05). The material of the light-shielding resin layer was curable resin composition 2, and a SiO layer with a radius of 0.25 mm and a thickness of 0.65 mm was provided on the -z side of the curable resin composition 2. For this model, the calculation range was changed to match the radius and thickness of the Fresnel zone plate, and the wavelength λ was changed to 450 nm. The electric field intensity (Field) in the xz plane at y = 0 was calculated by the FDTD method in the same manner as in Example 5. The distribution of the obtained electric field intensity E is shown in Figure 22. The FWHM in the x direction at y = 0, the position in the z direction where the electric field intensity is maximum, was 0.6 μm, and the light-collecting performance was sufficiently high to be applicable to imaging applications. However, the electric field intensity |E| 2 (V 2 / m 2 ) is the electric field strength |E| at the z-direction position y=0 where |E| 2 (V 2 / m 2 ) is 0.5 (V 2 / m 2 ) did not provide a large concentration of light compared to the incident light electric field, and was insufficient for high-sensitivity imaging.

[0143] [Example 12] In electromagnetic field calculation simulation software (Ansys Lumerical manufactured by Ansys), the height direction is the z direction, the xy plane is the radial direction, and the curable resin composition 2 constituting the shielding structure is used, and the radius, height μm, focal length f in the above formula (1), wavelength λ, number of shielding regions, finest line width, curable resin composition according to Table 1 below, in the Fresnel zone plate changed for each sample (12-1, 12-2, 12-3), a height of 1 mm was provided with SiO 2 , for this model, the radius of the Fresnel zone plate was changed to the calculation range according to the thickness, and the wavelength λ was changed to 450 nm, in the same manner as in Example 5, the electric field strength (Field) of the xz plane at y = 0 was calculated using the FDTD method and the Far Field method. The electric field strength obtained for each sample is shown in Table 1 below. In Samples 12-1 and 12-2, sufficient electric field strength was obtained at the focusing position. In Sample 12-3, whose focal length f was 75 cm, the electric field strength |E| at the z position (y=0) where the electric field strength was maximum, which is the focusing position, was 2 is 0.8 (V 2 / m 2 ) did not provide a large concentration of light compared to the incident light electric field, and was insufficient for high-sensitivity imaging.

[0144]

[0145] Comparative Example 1 In Comparative Example 1, the characteristics of a Fresnel zone plate with a light-shielding resin layer made of chromium (Cr), which is typically formed by etching, were evaluated. An electromagnetic field calculation simulation software (Ansys Lumerical, manufactured by Ansys) was used. The thickness direction of the light-shielding resin layer (the optical axis direction of the diffractive optical element) was defined as the z direction, and on an xy plane perpendicular to the z direction, a light-shielding resin layer with a radius of 0.107 mm, a thickness of 10 nm, and a diffraction pattern in the form of a Fresnel zone plate with a focal length f = 1 mm and a wavelength λ = 450 nm in the above formula (1) was input. The number of light-shielding regions was 11, and the finest line width was 18.3 μm (F-number 4.55). A SiO2 layer with a radius of 0.25 mm and a thickness of 0.65 mm was provided on the -z side of the light-shielding resin layer. For this model, the calculation range was changed to match the line segment length, width, and thickness of the linear zone plate shape, and the wavelength λ was changed to 450 nm. Except for this, the electric field strength (Field) in the xz plane at y = 0 was calculated using the FDTD method and Far Field calculation in the same manner as in Example 5. The obtained electric field strength |E| 2 From the distribution, the FWHM in the x direction at z=1 mm, y=0 was 2.7 μm, which was insufficient for imaging purposes.

[0146] Comparative Example 2 In Comparative Example 2, the characteristics of a Fresnel zone plate made of a curable resin composition without absorption properties were evaluated. An electromagnetic field calculation simulation software (Ansys Lumerical, manufactured by Ansys) was used. The thickness direction of the light-shielding resin layer (the optical axis direction of the diffractive optical element) was defined as the z direction, and on an xy plane perpendicular to the z direction, a light-shielding resin layer made of a Fresnel zone plate with a radius of 0.06 mm, a thickness of 2.5 μm, a focal length f of 0.1 mm in the above formula (1), and a wavelength of 650 nm was input. The number of light-shielding regions was 8, and the finest line width was 2.7 μm (F-number: 0.11). The material of the light-shielding resin layer was a hypothetical curable resin composition without absorption properties, and a SiO2 layer with a radius of 0.06 mm and a thickness of 0.65 mm was provided on the -z side of the curable resin composition. For this model, the calculation range was changed to match the radius and thickness of the Fresnel zone plate shape, and the wavelength λ was changed to 650 nm. Except for this, the electric field intensity (Field) in the xz plane at y = 0 was calculated by the FDTD method in the same manner as in Example 5. 2 The FWHM in the x direction at the z position, y=0, where the value is maximum, was 3.2 μm, which was insufficient for light-collecting performance for imaging purposes.

[0147] Comparative Example 3 In Comparative Example 3, the characteristics of a Fresnel zone plate with a light-shielding layer made of chromium (Cr), which is typically formed by etching, were evaluated. The thickness direction of the light-shielding layer (the optical axis direction of the diffractive optical element) was defined as the z direction, and a light-shielding layer consisting of a Fresnel zone plate with a radius of 0.72 mm, a thickness of 0.05 μm, a focal length f = 105 cm in the above formula (1), and a wavelength λ = 450 nm was input into electromagnetic field calculation simulation software (Ansys Lumerical, manufactured by Ansys). The number of light-shielding regions was six, and the finest line width was 33.5 μm (F-number 729). The material of the light-shielding layer was chromium (Cr), and a SiO2 layer with a radius of 0.72 mm and a thickness of 0.65 mm was provided on the -z side of the light-shielding layer. For this model, the calculation range was changed to match the radius and thickness of the Fresnel zone plate shape, and the wavelength λ was changed to 450 nm. The electric field intensity (Field) of the xy plane at a position 0.3 μm away from the Fresnel zone plate in the z direction was calculated using the FDTD method in the same manner as in Example 5. The calculated electric field intensity was converted into a zbf file and then input into ray tracing simulation software (ZEMAX OPTICSTUDIO, manufactured by Ansys). An image was placed at a position 105 cm from the input plane, and the light intensity at the image plane was simulated. At the focal length, sufficient focusing intensity was not obtained.

[0148] The diffractive optical element and the method for manufacturing a diffractive optical element of the present invention are thin diffractive optical elements that combine high light-collecting performance with high mass productivity, which can be manufactured without an etching step, and the method for manufacturing such a diffractive optical element, which can be suitably used for manufacturing diffractive optical lenses for imaging, optical lenses for optical sensors, optical lenses for displays, and optical lenses for optical communication.

[0149] 1: diffractive optical element 10: substrate 10a: main surface 20: resin layer

Claims

1. A diffractive optical element that diffracts incident light within a wavelength range of 410 nm to 1,100 nm, comprising: a substrate that transmits the incident light; and a light-shielding resin layer that is formed from a curable resin composition and that has irregularities on the main surface of the substrate and that forms a diffraction pattern that is substantially concentric when viewed in a direction perpendicular to the main surface of the substrate, and that blocks light of at least some of the wavelengths of the incident light.

2. A diffractive optical element according to claim 1, wherein the shape of the diffraction pattern of the light-shielding resin layer when viewed in a direction perpendicular to the main surface of the substrate is any one of a Fresnel zone plate shape, a linear zone plate shape, and a fractal zone plate shape.

3. The diffractive optical element according to claim 2, wherein the light-shielding resin layer includes at least one resin layer having a maximum width in the radial direction of 2 μm or less.

4. The diffractive optical element according to claim 2, wherein the light-shielding resin layer has a thickness of 2 μm or less.

5. A diffractive optical element according to claim 2, wherein when light of a wavelength λ falling within the range of 410 nm to 1,100 nm is incident as a parallel beam from a direction perpendicular to the main surface of the substrate, the focal length f is defined as the distance between the substrate and the focusing position D of the light of wavelength λ, and the focal length f is 2 μm or more and 100 cm or less.

6. The diffractive optical element according to claim 2, wherein when light of a wavelength λ falling within the range of 410 nm to 1,100 nm is incident as parallel rays from a direction perpendicular to the main surface of the substrate, the focal length f is defined as the distance between the substrate and the focal point D of the light of wavelength λ, and the focal length f is defined as the distance between the substrate and the focal point D. The value obtained by dividing the focal length f by the diameter of the circumscribing circle of the diffraction pattern when viewed in a direction perpendicular to the main surface of the substrate is within the range of 0.2 to 4.

0.

7. A diffractive optical element according to claim 2, wherein the light-shielding resin layer includes a structure in which the boundary at which the light-shielding resin layer changes into a region other than the light-shielding resin layer is 250 or more in the radial direction from the center to the outer edge of the diffraction pattern when viewed in a direction perpendicular to the main surface of the substrate.

8. A diffractive optical element according to claim 1, wherein the light-shielding resin layer has a diffraction pattern in the shape of a photon sieve plate when viewed in a direction perpendicular to the main surface of the substrate.

9. The diffractive optical element according to claim 8, wherein the light-shielding resin layer has a thickness of 2 μm or less.

10. The diffractive optical element according to claim 8, wherein when light of a wavelength λ falling within the range of 410 nm to 1,100 nm is incident as parallel rays from a direction perpendicular to the main surface of the substrate, the focal length f is defined as the distance between the substrate and the focusing position D of the light of wavelength λ, and the focal length f is within the range of 2 μm to 100 cm.

11. The diffractive optical element according to claim 8, wherein when light of a wavelength λ falling within the range of 410 nm to 1,100 nm is incident as parallel rays from a direction perpendicular to the main surface of the substrate, the focal length f is defined as the distance between the substrate and the focal point D of the light of wavelength λ, and the focal length f is defined as the distance between the substrate and the focal point D. The value obtained by dividing the focal length f by the diameter of the circumscribing circle of the diffraction pattern when viewed in a direction perpendicular to the main surface of the substrate is within the range of 0.2 to 4.

0.

12. A diffractive optical element as described in claim 1, wherein the light-shielding resin layer includes a structure in which the boundary at which the light-shielding resin layer changes into a region other than the light-shielding resin layer is 250 or more in the radial direction from the center to the outer edge of the diffraction pattern when viewed in a direction perpendicular to the main surface of the substrate.

13. The diffractive optical element according to any one of claims 1 to 12, wherein the curable resin composition is a radiation-sensitive curable resin composition.

14. The diffractive optical element according to claim 13, wherein the curable resin composition is an electromagnetic wave curable resin composition or an electron beam curable resin composition.

15. The diffractive optical element according to claim 14, wherein the curable resin composition is an ultraviolet-curable resin composition.

16. A diffractive optical element according to any one of claims 1 to 12, wherein the light-shielding resin layer has a minimum transmittance of less than 50% for light of any wavelength λ within the wavelength range of 410 nm to 1,100 nm per 1 μm of optical path length for the incident light.

17. The diffractive optical element according to claim 16, wherein the light-shielding resin layer has a maximum extinction coefficient per 1 μm of optical path length for the incident light in the range of 0.0001 to 1.

1.

18. The diffractive optical element according to claim 17, wherein the light-shielding resin layer has a maximum transmittance of 50% or more for light of any wavelength λ within the wavelength range of 410 nm to 1,100 nm per 1 μm of optical path length for the incident light.

19. A method for producing a diffractive optical element applicable to incident light within a wavelength range of 410 nm to 1,100 nm, comprising: (A) a step of preparing a substrate that transmits the incident light; (B) a step of applying a material containing a curable resin composition to a main surface of the substrate to form a coating film; (C) a step of curing a portion of the coating film to form a light-shielding resin layer that blocks the incident light on a portion of the main surface of the substrate; and (D) a step of removing, after step (C), the coating film in a portion different from the light-shielding resin layer from the main surface of the substrate.

Images