Optical element, optical apparatus, imaging device, and method for manufacturing optical element

Abstract

To provide an optical element that prevents a relative displacement of a second transparent member to a first transparent member.SOLUTION: An optical element comprises: a first transparent member; a second transparent member that is different in coefficient of linear expansion from the first transparent member; and an adhesive member that bonds the second transparent member and the first transparent member to each other. The first transparent member has a first principal surface. The second transparent member has a second principal surface partially in contact with the first principal surface. The adhesive member is separated from a position where the first principal surface and the second principal surface are in contact with each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an optical element, an optical apparatus, an imaging device, and a method for manufacturing an optical element. [Background technology]

[0002] Conventionally, in the optical system of an optical device, the lenses included in the optical system are made of resin lenses, thereby reducing the weight of the optical device. It is preferable that the lens is firmly fixed to the mounting member with high positional accuracy without causing distortion in the optically functional surface. One method for attaching a lens to the mounting member is to attach the lens to the mounting member by deforming the mounting member by heat crimping. When the lens is a resin lens, the resin lens may deform during heat crimping, which can cause deterioration in the optical performance of the resin lens. Patent Document 1 proposes a method in which a glass lens is fixed to the mounting member by heat crimping, and the resin lens is bonded to the glass lens with an adhesive. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-72766 Summary of the Invention [Problem to be solved by the invention]

[0004] However, after the two lenses are exposed to low temperatures, when the temperature of the environment in which the two lenses are placed returns to room temperature, one of the two lenses may become displaced relative to the other lens.

[0005] An object of the present invention is to provide an optical element in which relative displacement of a second transparent member with respect to a first transparent member is suppressed. [Means for solving the problem]

[0006] Book Disclosure of One aspect The present invention provides a light-emitting device comprising: a first transparent member; a second transparent member having a linear expansion coefficient different from that of the first transparent member; and an adhesive member that bonds the second transparent member to the first transparent member, the first transparent member having a first main surface, and the second transparent member , th 2 main a surface, and a protrusion portion where a part of the second main surface protrudes and contacts the first main surface, and an outer peripheral surface is provided; The adhesive member is spaced from a position where the first main surface and the second main surface contact each other. and contacting the outer peripheral surface and spaced apart from the protrusion. Characterized by It is an optical element .

[0007] The method for manufacturing an optical element of the present invention is characterized in that a portion of a first transparent member and a portion of a second transparent member are brought into contact with each other, adhesive is supplied away from the position where the first transparent member and the second transparent member are in contact, and the adhesive is hardened to form an adhesive member that bonds the second transparent member and the first transparent member. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress the relative displacement of the second transparent member with respect to the first transparent member. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram showing a schematic configuration of a digital camera as an example of an imaging apparatus according to an embodiment. [Figure 2] 1A is a plan view of an optical unit according to an embodiment, FIG. 1B is a cross-sectional view of the optical unit according to an embodiment, and FIG. 1C is an enlarged cross-sectional view of the optical unit according to an embodiment. [Figure 3] 1A is a plan view of an optical unit of a comparative example, FIG. 1B is a cross-sectional view of the optical unit of a comparative example, and FIG. 1C is an enlarged cross-sectional view of the optical unit of a comparative example. [Figure 4] 1(a) to 1(d) are explanatory views of the steps of a method for manufacturing an optical element according to an embodiment. [Figure 5] 10(a) and 10(b) are explanatory diagrams of a modified optical unit. [Figure 6] 10(a) and 10(b) are explanatory diagrams of a modified optical unit. [Figure 7] 1 is a table showing the conditions and results of Examples 1 to 17 and Comparative Examples 1 and 2. [Figure 8] 1 is a table showing the conditions of Examples 1 to 17 and Comparative Examples 1 and 2. [Figure 9] 1 is a table showing the conditions of Examples 1 to 17 and Comparative Examples 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0011] [Imaging device] 1 is an explanatory diagram showing a schematic configuration of a digital camera 600, which is an example of an imaging device according to an embodiment. The digital camera 600 is, for example, a single-lens reflex digital camera. The digital camera 600 includes a camera body 602, which is an example of an imaging device body, and a lens barrel 601, which is an example of an optical device. The lens barrel 601 is an interchangeable lens that is detachable from the camera body 602.

[0012] The lens barrel 601 has a housing 610 and an optical system 611 arranged inside the housing 610. The optical system 611 is an imaging optical system, and includes multiple lenses 603, an optical element 10, an aperture 605, and multiple lenses 606 arranged on an optical axis L0. Light from a subject passes through the multiple lenses 603, the optical element 10, the aperture 605, and the multiple lenses 606, and is received by an image sensor 621 in the camera body 602.

[0013] The optical element 10 includes an optical unit 100 and an inner cylinder 604 that supports the optical unit 100. The optical unit 100 includes a lens 11 that is an example of a first transparent member, and a lens 12 that is an example of a second transparent member. "Transparent" means that the transmittance of light in the wavelength range of 400 nm or more and 780 nm or less is 10% or more.

[0014] The lens 11 is held by an inner cylinder 604, and the lens 12 is fixed to the lens 11. The inner cylinder 604 is an example of a holding member. The inner cylinder 604, i.e., the optical element 10, is disposed inside the housing 610 so as to be movable in the direction of the optical axis L0 relative to the housing 610 for focusing and zooming.

[0015] The camera body 602 has a housing 620 and the above-described image sensor 621 disposed inside the housing 620. The image sensor 621 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor.

[0016] During an observation period before capturing an image, light from the subject that passes through an optical system 611 of the lens barrel 601 is reflected by a primary mirror 607 in a housing 620 of the camera body 602. The reflected light passes through a prism 622 and then passes through a viewfinder lens 612, where a captured image is displayed to the photographer. The primary mirror 607 is, for example, a half mirror. The light that passes through the primary mirror 607 is reflected by a secondary mirror 608 toward an AF (autofocus) unit 613. This reflected light is used, for example, for distance measurement. The primary mirror 607 is attached to a primary mirror holder 640 with an adhesive or the like, and is supported by the primary mirror holder 640. When the photographer presses a shutter button (not shown) during capture, a drive mechanism (not shown) moves the primary mirror 607 and secondary mirror 608 out of the optical path, and a shutter 609 opens. As a result, light from the subject that has passed through the optical system 611 of the lens barrel 601, i.e., a captured light image, is focused on the image sensor 621. As a result, a captured image is obtained from the image sensor 621. 5 is configured so that the brightness and focal depth during imaging can be changed by changing the aperture area.

[0017] [Optical unit] Fig. 2(a) is a plan view of the optical unit 100 according to the embodiment. Fig. 2(b) is a cross-sectional view of the optical unit 100 according to the embodiment. Fig. 2(c) is an enlarged cross-sectional view of the optical unit 100 according to the embodiment. Fig. 2(b) shows a cross-section of the optical unit 100 taken along line IIB-IIB shown in Fig. 2(a). Fig. 2(c) shows an enlarged view of a portion of Fig. 2(b).

[0018] As described above, the optical unit 100 includes the lens 11 and the lens 12. The lens 11 and the lens 12 are arranged in contact with each other with the central axes of the lens 11 and the lens 12 overlapping each other.

[0019] The outer shape of each of the lenses 11 and 12 is circular when viewed in the direction of the optical axis L0. The optical axis L0 is also a central axis passing through the center of each of the lenses 11 and 12. When viewed in the direction of the optical axis L0, the lens 11 is larger than the lens 12. In other words, the lens 11 has a larger diameter than the lens 12. Hereinafter, the direction of the optical axis L0 is referred to as the Z direction. Furthermore, the direction perpendicular to the optical axis L0 and extending from the optical axis L0 is referred to as the radial direction R1. Furthermore, the direction around the optical axis L0 centered on the optical axis L0 is referred to as the circumferential direction R2.

[0020] Lens 11 includes a first principal surface, principal surface 111, a rear principal surface 112 of principal surface 111, and an outer peripheral surface 113. Lens 12 includes a second principal surface, principal surface 121, a rear principal surface 122 of principal surface 121, and an outer peripheral surface 123. Part or all of each of principal surfaces 111, 112, 121, and 122 is used as an optically functional surface.

[0021] The main surface 121 faces the main surface 111 at a distance from the main surface 111 in the Z direction. That is, the main surfaces 111 and 121 are disposed with a gap between them. The shape of each of the main surfaces 111, 112, 121, and 122 is not particularly limited, but is preferably any of a concave spherical surface, a convex spherical surface, an axisymmetric aspherical surface, a flat surface, or the like.

[0022] The lens 11 is fixed to an inner wall 6041 of the inner cylinder 604 shown in Fig. 1. In this embodiment, the inner cylinder 604 is made of resin. The lens 11 is fixed to the inner cylinder 604 by heat caulking.

[0023] The lens 12 has a protrusion 125 that protrudes from the main surface 121. The protrusion 125 protrudes toward the main surface 111 of the lens 11. In this embodiment, the protrusion 125 is formed in a ring shape when viewed in the Z direction. The protrusion 125 is for positioning the main surface 121 at a predetermined distance from the main surface 111, and is provided in contact with the main surface 111. This allows the lens 12 to be positioned with high precision relative to the lens 11 so that the main surface 121 is spaced a predetermined distance from the main surface 111 in the Z direction. Note that depending on the shapes of the lenses 11 and 12, the main surfaces 121 and 111 can also be positioned without providing the protrusion 125. Therefore, the main surface 121 does not need to have the protrusion 125. However, from the perspective of positioning the lens 12 with high precision relative to the lens 11, it is preferable that the main surface 121 have the protrusion 125.

[0024] The protrusion 125 includes an end surface 1251, which is a tip surface. The end surface 1251 faces the main surface 111 and is in partial contact with the main surface 111. That is, the end surface 1251 and / or the main surface 111 are roughened, so the end surface 1251 is in partial contact with the main surface 111. Specifically, at least one of the main surface 111 and the end surface 1251 is not a smooth surface but has irregularities on the order of microns or submicrons. In the example of FIG. 2(c), the main surface 111 is roughened. Therefore, the end surface 1251 is in partial contact with the main surface 111, and there is a small gap between the end surface 1251 and the main surface 111 at the locations where the end surface 1251 is not in contact.

[0025] The lens 11 includes a substrate 110, which is an example of a first transparent substrate. The substrate 110 is the lens body. The lens 11 may include a functional film formed on the surface of the substrate 110. The functional film is composed of at least one functional layer. The functional layer is a coating layer, and examples thereof include an anti-reflection layer and a hydrophilic layer. The anti-reflection layer is formed, for example, from a paint containing micron-order particles. The hydrophilic layer is composed of, for example, SiO2.

[0026] The lens 12 includes a substrate 120, which is an example of a second transparent substrate. The substrate 120 is the lens body. The lens 12 may include a functional film formed on the surface of the substrate 120. The functional film is composed of at least one functional layer. The functional layer is a coating layer, and examples thereof include an anti-reflection layer and a hydrophilic layer. The hydrophilic layer is composed of, for example, SiO2.

[0027] The material of the substrate 110 is glass such as optical glass, which can be selected from silicate glass, borosilicate glass, phosphate glass, quartz glass, glass ceramics, and the like.

[0028] The material of the substrate 120 is different from the material of the substrate 110, and in this embodiment is a resin. The resin is preferably an optical resin. The optical resin can be selected from cycloolefin polymer, acrylic resin, polyester resin, polycarbonate, etc.

[0029] Here, an optical unit of a comparative example will be described. In the following description, lens 11 will also be referred to as a glass lens, and lens 12 will also be referred to as a resin lens. FIG. 3(a) is a plan view of optical unit 100X of a comparative example. FIG. 3(b) is a cross-sectional view of optical unit 100X of a comparative example. FIG. 3(c) is an enlarged cross-sectional view of optical unit 100X of a comparative example. FIG. 3(b) illustrates a cross-section of optical unit 100X taken along line IIIB-IIIB shown in FIG. 3(a). FIG. 3(c) illustrates an enlarged portion of FIG. 3(b).

[0030] The optical unit 100X of the comparative example includes a lens 11 and a lens 12, similar to the present embodiment. The optical unit 100X of the comparative example includes a plurality of, for example, six, adhesive members 13X formed with an adhesive. The plurality of adhesive members 13X are arranged at intervals in the circumferential direction R2. Each adhesive member 13X is arranged between the lens 11 and the lens 12. Each adhesive member 13X is arranged in contact with the main surface 111 and the main surface 121. At least a portion of each adhesive member 13X is interposed in the gap between the main surface 111 of the lens 11 and the end surface 1251 of the protrusion 125 of the lens 12.

[0031] That is, each adhesive member 13X includes an adhesive portion 131X that is a portion interposed in the gap between the main surface 111 and the end surface 1251, and an adhesive portion 132X that contacts the main surface 111, the main surface 121, and the outer surface 1252 of the protrusion 125. The adhesive portion 131X and the adhesive portion 132X are formed continuously and integrally.

[0032] When an optical device having optical unit 100X of the comparative example is used in a low-temperature environment and then returned to a room temperature environment, lens 12 may be displaced relative to lens 11, i.e., decentered. In this way, the fixed position of lens 12 may change relative to lens 11, which may result in a decrease in imaging performance.

[0033] Therefore, the present inventors observed the optical unit 100X and found that the adhesive portions 131X included in some of the adhesive members 13X among the plurality of adhesive members 13X were partially or entirely peeled off from the protrusion 125 or the lens 11. For example, this is a phenomenon in which the adhesive portions 131X are partially or entirely peeled off in each of four of the six adhesive members 13X. The present inventors believed that the occurrence of such interfacial peeling would cause an imbalance in adhesive force among the adhesive members 13X when the optical unit 100X was returned to a room temperature environment from a low temperature environment, causing the lens 12 to become decentered with respect to the lens 11.

[0034] The inventors have come to the following conclusion about the cause of such interfacial peeling. That is, the material of the substrate 120 is different from the material of the substrate 110. Because the material of the substrate 120 is different from the material of the substrate 110, the linear expansion coefficient of the substrate 120 is different from the linear expansion coefficient of the substrate 110. That is, the linear expansion coefficient of the glass substrate 110 is smaller than the linear expansion coefficient of the resin substrate 120. When the temperature of the environment in which the optical unit 100X is placed changes from room temperature to a low temperature, the linear expansion coefficient of the resin substrate 120 increases. 2 The lens 12 including the lens 10 is made of a glass substrate 1 1 The amount of thermal contraction in the radial direction R1 is larger than that of the lens 11 including the lens 12. Here, room temperature refers to normal temperature, for example, 23°C ± 2°C. Furthermore, low temperature refers to, for example, below freezing. When an optical device is used in a low-temperature environment, thermal stress occurs in each adhesive member 13X due to the difference in the amount of thermal contraction between the lens 11 and the lens 12. Furthermore, the thickness T' of the adhesive portion 131X is thinner than the thickness T'' of the adhesive portion 132X. Therefore, the adhesive portion 131X, which is thinner than the adhesive portion 132X, cannot follow the contraction of the lens 11 and the lens 12 in the radial direction R1, and it is thought that the thermal stress generated in the adhesive portion 131X of the adhesive member 13X caused interfacial peeling to occur in the adhesive portion 131X of the adhesive member 13X.

[0035] 2(a), the optical unit 100 of this embodiment includes at least one adhesive member made of adhesive, and in this embodiment includes a plurality of adhesive members 13, for example, six adhesive members 13. Each adhesive member 13 has a different shape from the adhesive member 13X. That is, unlike the adhesive member 13X of the comparative example, each adhesive member 13 is not interposed in the gap between the main surface 111 and the end surface 1251.

[0036] The lenses 11 and 12 are bonded together with a plurality of adhesive members 13. In this embodiment, the lens 12 is fixed to the lens 11 by adhesive bonding with a plurality of adhesive members 13. The plurality of adhesive members 13 are arranged at intervals in the circumferential direction R2. In this embodiment, the plurality of adhesive members 13 are arranged at equal intervals in the circumferential direction R2, for example, at intervals of 60 degrees around the optical axis L0. Some or all of the adhesive members 13, all of them in this embodiment, are arranged between the lenses 11 and 12. Each adhesive member 13 is arranged in contact with the main surface 111 and the main surface 121. That is, each adhesive member 13 bonds the main surface 111 and the main surface 121 together. Each adhesive member 13 is also positioned outward in the radial direction R1 from the protrusion 125.

[0037] In this embodiment, each adhesive member 13 is disposed at a distance from the protrusion 125. That is, there is a gap between the outer surface 1252 of the protrusion 125 and each adhesive member 13. As a result, each adhesive member 13 does not have a thin adhesive portion 131X like the comparative example, and therefore, interfacial peeling can be suppressed in each adhesive member 13. That is, the thickness T of each adhesive member 13 is the same as the distance between the principal surface 111 and the principal surface 121 and is thicker than the thickness T' of the comparative example. Therefore, the occurrence of interfacial peeling in each adhesive member 13 in a low-temperature environment is suppressed. Therefore, even if the temperature of the environment in which the optical element 10 is placed changes from low temperature to room temperature after the optical element 10 is exposed to a low-temperature environment, the balance of adhesive forces in each adhesive member 13 is maintained, and relative displacement of the lens 12 with respect to the lens 11, i.e., decentering, is suppressed. When the lens 12 is used as a reference, relative displacement of the lens 11 with respect to the lens 12 is suppressed.

[0038] Furthermore, since the adhesive members 13 are arranged at equal intervals in the circumferential direction R2, the stress generated in each adhesive member 13 due to thermal contraction of each lens 11, 12 is uniform, and displacement of the lens 12 relative to the lens 11 is suppressed.

[0039] Even if the lens 11 includes a functional film, the majority of the lens 11 is the substrate 110, and therefore, thermal shrinkage of the substrate 110 can be said to be thermal shrinkage of the lens 11. Also, even if the lens 12 includes a functional film, the majority of the lens 12 is the substrate 120, and therefore, thermal shrinkage of the substrate 120 can be said to be thermal shrinkage of the lens 12.

[0040] A hydrophilic layer such as SiO2 may be used as the functional film or the outer layer of the functional film formed on the surfaces of the substrates 110 and 120, respectively. This improves the adhesion at the adhesive interface of the adhesive portion 131, and effectively prevents peeling of the adhesive portion 131. Furthermore, the surfaces of the lenses 11 and 12 may be subjected to surface modification such as atmospheric pressure plasma treatment or UV ozone treatment to chemically bond carbonyl groups, carboxyl groups, etc. This improves the adhesion at the adhesive interface of the adhesive portion 131, and effectively prevents peeling of the adhesive portion 131.

[0041] The linear expansion coefficient of the substrate 110 is α1, and the linear expansion coefficient of the substrate 120 is α2. In this embodiment, it is more effective when the difference between the linear expansion coefficient α1 of the substrate 110 and the linear expansion coefficient α2 of the substrate 120 is large so that the relationship α1 / α2≦0.2 is satisfied. That is, when the linear expansion coefficient α1 and the linear expansion coefficient α2 are large such that α1 / α2 is 0.2 or less, 2 Even in a combination where there is a large difference between the lens 11 and the lens 12, it is possible to effectively alleviate the thermal stress generated in each adhesive member 13 and effectively prevent peeling of each adhesive member 13. Therefore, it is possible to effectively prevent the relative displacement of lens 12 with respect to lens 11, i.e., decentering.

[0042] The size relationship between lens 11 and lens 12 is not limited to the above-mentioned relationship. Furthermore, as the radius of lens 12, which has resin base material 120, increases, the amount of contraction of lens 12 in radial direction R1 at low temperatures increases. This increases the thermal stress generated in each adhesive member 13, but because each adhesive member 13 has the above-mentioned configuration, decentering of lens 12 with respect to lens 11 can be suppressed.

[0043] Next, the adhesive used to form each adhesive member 13 will be described. The adhesive member 13 is a cured product of an adhesive containing uncured resin. The adhesive member 13 includes a cured product of resin. Each adhesive member 13 is preferably a cured product of a cross-linked adhesive. That is, the adhesive is preferably a cross-linked adhesive. As the cross-linked adhesive, for example, a photo-curable adhesive such as an ultraviolet-curable adhesive containing an ultraviolet-curable resin, a heat-curable adhesive, or a moisture-curable adhesive can be used. Among these types of adhesives, a photo-curable adhesive is preferred. Among photo-curable adhesives, an ultraviolet-curable adhesive is more preferred. An ultraviolet-curable adhesive can be instantaneously cured by irradiating it with ultraviolet light. This improves the workability of application and also makes it easy to prevent the adhesive from seeping into the gap between the end surface 1251 of the protrusion 125 and the main surface 111.

[0044] The ultraviolet-curable adhesive preferably contains a photopolymerization initiator (A), a urethane-modified (meth)acrylate (B), and an acrylate monomer (C). Furthermore, the ultraviolet-curable adhesive preferably contains a thixotropy-imparting agent (D) such as silica fine particles to adjust the viscosity of the adhesive. Furthermore, the ultraviolet-curable adhesive preferably contains a spherical filler such as crystalline silica as an additive (E) to adjust the hardness of the adhesive after curing. A silane coupling agent may be added to the ultraviolet-curable adhesive to improve adhesion to the adherend.

[0045] The photopolymerization initiator (A) is not particularly limited, and examples thereof include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, 1-hydroxycyclohexylphenyl ketone (Irgacure 184; manufactured by BASF), 2-hydroxy-2-methyl-[4-(1-methylvinyl)phenyl]propanol oligomer (Esacure ONE; manufactured by Lambarty), 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (Irgacure 2959; manufactured by BASF), 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl -propan-1-one (Irgacure 127; BASF), 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651; BASF), 2-hydroxy-2-methyl-1-phenyl-propan-1-one (DAROCUR 1173; BASF), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Irgacure 907; BASF), 2-benzyl 2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-chlorothioxanthone, 2,4-diethylthioxanthone (Kayacure DETX-S: manufactured by Nippon Kayaku Co., Ltd.), 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, isopropylthioxanthone, 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)] (IRGACURE OXE01: manufactured by BASF), a mixture of oxyphenylacetic acid 2-[2-oxo-2-phenylacetoxyethoxy]ethyl ester and oxyphenylacetic acid 2-(2-hydroxy-ethoxy)ethyl ester (IRGACURE 754), and the like.

[0046] The urethane-modified (meth)acrylate (B) preferably has a flexible polyether skeleton, such as a structure in which a diisocyanate compound, which is a reaction product of a polyalkylene glycol and a diisocyanate, is further reacted with an acrylate having a hydroxyl group.

[0047] The acrylate monomer (C) is not particularly limited, but a (meth)acrylate having one (meth)acryloyl group in the molecule can be suitably used. Specifically, (meth)acrylates having an alkyl group having 5 to 25 carbon atoms, such as octyl (meth)acrylate, isooctyl (meth)acrylate, isoamyl (meth)acrylate, lauryl (meth)acrylate, isodecyl (meth)acrylate, stearyl (meth)acrylate, cetyl (meth)acrylate, isomyristyl (meth)acrylate, isostearyl (meth)acrylate, and tridecyl (meth)acrylate, and benzyl (meth)acrylate can be used. acrylate, tetrahydrofurfuryl (meth)acrylate, acryloylmorpholine, cyclic trimethylolpropane formal acrylate, phenylglycidyl (meth)acrylate, tricyclodecane (meth)acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 1-adamantyl acrylate, 2-methyl-2-adamantyl Examples of suitable adhesives include (meth)acrylates having a cyclic skeleton such as acrylate, 2-ethyl-2-adamantyl acrylate, 1-adamantyl methacrylate, polypropylene oxide-modified nonylphenyl (meth)acrylate, ethoxylated o-phenylphenol acrylate, and dicyclopentadieneoxyethyl (meth)acrylate; (meth)acrylates having an alkyl group having 2 to 7 carbon atoms and a hydroxyl group; polyalkylene glycol (meth)acrylates such as ethoxydiethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, and polypropylene oxide-modified nonylphenyl (meth)acrylate; ethylene oxide-modified phenoxylated phosphate (meth)acrylate, ethylene oxide-modified butoxylated phosphate (meth)acrylate, ethylene oxide-modified octyloxylated phosphate (meth)acrylate, and caprolactone-modified tetrafurfuryl (meth)acrylate. Furthermore, it is preferable to incorporate an amide group-containing (meth)acrylate into the adhesive to improve adhesion to a resin lens.Examples of amide group-containing (meth)acrylates include N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropylacrylamide, N-butyl(meth)acrylamide, N,N-butoxymethyl(meth)acrylamide, hydroxyethylacrylamide, and acryloylmorpholine, which can be used alone or in combination of two or more. Among these, it is preferable to use N,N-dimethylacrylamide (DMAA) because of its excellent adhesion to cycloolefin polymers, which are difficult to adhere to as resin lenses.

[0048] The presence of N,N-dimethylacrylamide in the adhesive member 13 can be confirmed by analysis using a gas chromatograph mass spectrometer. In this case, a thermal desorption device or a headspace sampler is preferably attached as a pretreatment device. Pretreatment conditions include, for example, a heating temperature of 80°C and a heating time of 30 minutes. Gas chromatograph temperature conditions include, for example, holding at 40°C for 3 minutes, then increasing the temperature to 320°C at a rate of 20°C / min, and holding at 320°C for 5 minutes. This allows N,N-dimethylacrylamide to be detected. When performing mass analysis using the EI method, which is the most commonly used method for gas chromatograph mass spectrometry, focusing on m / z = 55, 72, and 99 makes it easy to determine whether N,N-dimethylacrylamide has been detected. The gas chromatograph mass spectrometry device is not particularly limited, but examples include the Trace GC Ultra manufactured by Thermo Fisher Scientific.

[0049] Here, assuming that α1 / α2 is smaller under the condition of α1<α2, the substrate 120, whose linear expansion coefficient is α2, will experience more thermal contraction at low temperatures than the substrate 110, whose linear expansion coefficient is α1. Therefore, in order to allow each adhesive member 13 to follow the difference in the amount of thermal contraction between the substrates 110 and 120, it is preferable that the elastic modulus E of each adhesive member 13 be as small as possible under a temperature condition of -30°C. In this embodiment, the elastic modulus E is the storage modulus. Note that the elastic modulus E of the adhesive member 13 under a temperature environment of -30°C can be measured using a microindentation hardness test using a nanoindenter.

[0050] The thickness T of the adhesive member 13 is preferably large from the viewpoint of easily adapting to the difference in the amount of thermal contraction between the base materials 110 and 120. When the thickness T of the adhesive member 13 is large, even if an adhesive with a relatively large elastic modulus E is used, peeling can be suppressed in a low-temperature environment, changes in the fixed position of the lens 12 relative to the lens 11 can be suppressed, and a high adhesive strength can be maintained due to the large elastic modulus E.

[0051] The thickness T of the adhesive member 13 is preferably 0.2 mm or more and 1.5 mm or less from the viewpoints of achieving a large adhesive force and suppressing changes in the fixing position. The thickness T of the adhesive member 13 is more preferably 0.5 mm or more and 1.1 mm or less. Furthermore, when the thickness T of the adhesive member 13 is small, it is preferable to select an adhesive that reduces the elastic modulus E of the adhesive member 13 in a temperature environment of -30°C from the viewpoint of suppressing thermal stress. The elastic modulus E of the adhesive member 13 in a temperature environment of -30°C is preferably 0.5 GPa or more and 1.7 GPa or less. The elastic modulus E of the adhesive member 13 in a temperature environment of -30°C is more preferably 0.7 GPa or more and 1.2 GPa or less from the viewpoints of achieving a large adhesive force and suppressing changes in the fixing position. Here, -30°C includes an error of ±0.5°C.

[0052] In this embodiment, when the elastic modulus of adhesive member 13 at a temperature condition of -30°C is E [GPa] and the thickness of the portion of adhesive member 13 between lens 11 and lens 12 is T [mm], it is preferable to satisfy the relationship E≦2.3×T+2.5. By satisfying this relationship, even when optical element 10 is used at low temperatures, it is possible to further suppress changes in the fixed position of lens 12 relative to lens 11. Note that thickness T is the minimum thickness of the portion of adhesive member 13 between lens 11 and lens 12.

[0053] Furthermore, when the diameter of the lens 12 is large, the amount of contraction of the diameter of the lens 12 at low temperatures increases, and the thermal stress generated in each adhesive member 13 also increases. The elastic modulus of the adhesive member 13 under a temperature condition of -30°C is E [GPa], the thickness of the portion of the adhesive member 13 between the lens 11 and the lens 12 is T [mm], and the distance in the radial direction R1 between the central axis of the main surface 121, i.e., the optical axis L0, and the protrusion 125 is r [mm]. In this embodiment, the distance r is the shortest distance from the optical axis L0 to the protrusion 125. In other words, the distance r is the distance from the optical axis L0 to the inner surface 1253 of the protrusion 125. The optical unit 100 has a coefficient of elasticity satisfying E≦2.3 × It is preferable to satisfy the relationship T-0.08xr+2.5. By satisfying this relationship, the change in the fixed position of the lens 12 relative to the lens 11 can be more effectively suppressed.

[0054] [Method of manufacturing optical elements] The following describes a method for manufacturing the optical element 10. Figures 4(a) to 4(d) are explanatory diagrams of the steps of the method for manufacturing the optical element 10 according to the embodiment.

[0055] First, as shown in Fig. 4(a), lenses 11 and 12 are prepared, and lenses 11 and 12 are brought into contact with each other. Specifically, protrusion 125 of lens 12 is brought into contact with main surface 111 of lens 11. At this time, adjustment is made so that the central axes of lenses 11 and 12 overlap.

[0056] Next, as shown in FIG. 4(b), adhesive A is supplied between lens 11 and lens 12. A known method capable of dispensing a fixed amount of adhesive A is used to supply adhesive A. For example, adhesive A is applied between lens 11 and lens 12 from the vicinity of outer peripheral surface 123 of lens 12 using an air dispenser 41 or the like. In this embodiment, adhesive A is applied at six equally spaced locations in the circumferential direction R2 shown in FIG. 2(a).

[0057] When adhesive A is applied to each location, it spreads between lenses 11 and 12 at each location, but does not reach protrusions 125 and remains separated from protrusions 125. The viscosity of adhesive A is not particularly limited, but is preferably 3000 mPa·s or higher. If the viscosity of adhesive A is 3000 mPa·s or higher, adhesive A does not easily spread to protrusions 125.

[0058] From the viewpoint of workability in applying adhesive A and prevention of penetration into the gap between the end surface 1251 of the protrusion 125 and the main surface 111, adhesive A Viscosity of It is more preferable that the viscosity is 6000 mPa·sec or more and less than 30000 mPa·sec. If the viscosity is 30000 mPa·sec or more, the adhesive will have low wettability with respect to the lenses 11 and 12, and sufficient adhesive strength may not be obtained. The viscosity of adhesive A can be adjusted by adjusting the composition ratio of the urethane-modified acrylate (B) and the acrylate monomer (C).

[0059] The following methods can be considered as a method for achieving a state in which adhesive A and protrusion 125 are separated from each other. For example, because it is possible to adjust only the viscosity of the adhesive while maintaining the mechanical properties of the adhesive, such as adhesion and adhesive hardness, the viscosity may be adjusted by adding a thixotropy-imparting agent (D) such as silica fine particles to adhesive A. Also, it is effective to prevent adhesive A from coming into contact with protrusion 125 by, for example, applying a fluid such as grease that is incompatible with the adhesive and that maintains fluidity even when irradiated with ultraviolet light to the contact area between the resin lens and the glass lens in advance.

[0060] Thereafter, the adhesive A is cured. The adhesive A is, for example, an ultraviolet-curable adhesive. As shown in FIG. 4(c), the adhesive A is cured by irradiating it with ultraviolet light L1 from a light source 42. The light source 42 may be, for example, a high-pressure mercury lamp or an LED irradiator. When the adhesive A is cured, an adhesive member 13 that fixes the lens 12 to the lens 11 is formed. The adhesive member 13 is spaced from the protrusion 125. In this way, the lens 11 and the lens 12 are joined together with the adhesive member 13, and the optical unit 100 is obtained.

[0061] The obtained optical unit 100 may be annealed. By annealing, outgassing from the cured adhesive can be reduced, and the adhesive strength of the adhesive member 13 can be made stronger.

[0062] 4(d), the optical unit 100 is placed inside the inner cylinder 604, and a part of the inner wall 6041 of the inner cylinder 604 is thermally caulked to fix the lens 11 to the inner wall 6041 of the inner cylinder 604. Through the above steps, the optical element 10 is obtained.

[0063] The order of the steps is not limited to this. For example, the lens 11 may be fixed to the inner cylinder 604 by thermal caulking, and then the lens 12 may be adhesively fixed onto the lens 11. The number of adhesive members 13 is not limited to six, and may be two or more, for example, three.

[0064] [Variations] Modifications of the above embodiment will now be described. FIGS. 5(a) and 5(b) and 6(a) and 6(b) are explanatory diagrams of optical units of the modification examples. FIG. 5(a) shows an optical unit 100A of modification example 1, FIG. 5(b) shows an optical unit 100B of modification example 2, and FIGS. 6(a) and 6(b) show an optical unit 100C of modification example 3. FIG. 6(b) shows a cross section of optical unit 100C taken along line VIB-VIB shown in FIG. 6(a). Note that in the lens barrel 601 of the above embodiment, any of optical units 100A to 100C is used in place of optical unit 100.

[0065] As shown in FIG. 5(a), the optical unit 100A has a plurality of adhesive members 13A instead of a plurality of adhesive members 13. Each adhesive member 13A may be in contact with the main surface 111 of the lens 11, the main surface 121 of the lens 12, and the outer circumferential surface 123 of the lens 12. When manufacturing the optical unit 100A, the adhesive may be applied so that it overflows onto the outside of the lens 12. Because the adhesive members 13A contact the outer circumferential surface 123 of the lens 12, the lens 12 can be more firmly fixed to the lens 11. Therefore, when an optical element, i.e., a digital camera, is used in a low-temperature environment, decentering of the lens 12 with respect to the lens 11 can be more effectively suppressed.

[0066] 5(b), one adhesive member 13B may be disposed to surround the protruding portion 125. The adhesive member 13B is spaced apart from the protruding portion 125. When manufacturing the optical unit 100B, the adhesive may be applied between the lens 11 and the lens 12 over the entire circumferential direction R2.

[0067] 6(a) and 6(b), a lens 12C, which is an example of a second transparent member, may have a plurality of protrusions 125C spaced apart in the circumferential direction R2. Each of the plurality of adhesive members 13 is spaced apart from each of the plurality of protrusions 125C so as not to come into contact with any of the plurality of protrusions 125C. Note that the distance r is the shortest distance from the central axis of the lens 12, i.e., the optical axis L0, to the protrusion 125C closest to the optical axis L0 among the plurality of protrusions 125C. In other words, the distance r is the distance from the optical axis L0 to the inner surface 1253C of the protrusion 125C closest to the optical axis L0.

[0068] [Example] Below, experimental results will be described as Examples 1 to 17 corresponding to the above-described embodiments, and Comparative Examples 1 and 2 corresponding to the above-described comparative examples.

[0069] [Example 1] The manufacturing process of the optical unit 100 will be described. The lenses 11 and 12 did not have a functional film and were made of substrates 110 and 120, respectively. A glass lens using optical glass S-FPL53 (manufactured by Ohara Inc.) was prepared as the lens 11. The glass lens had a diameter of 35 mm, a flat surface R1, and a concave spherical surface R2. The radius of curvature R of the concave spherical surface was 190 mm.

[0070] A resin lens made of Zeonex E48R resin (manufactured by Zeon Corporation) was prepared as the lens 12. The resin lens had a diameter of 34 mm, an aspherical R1 surface, and a flat R2 surface. The protrusion 125 was ring-shaped and 0.8 mm high. The protrusion 125 was positioned 2 mm inward in the radial direction R1 from the outer peripheral surface 123. That is, in FIG. 2(b), the distance B in the radial direction R1 between the outer peripheral surface 123 and the outer surface 1252 of the protrusion 125 was 2 mm. The value of α1 / α2 was 0.24.

[0071] The protruding portion 125 of the lens 12 was brought into contact with the R1 surface of the lens 11, and adjustment was made so that the central axes of the lenses 11 and 12 overlapped.

[0072] The adhesive will be described. The adhesive used was an ultraviolet-curable adhesive. 2 parts by mass of Omnirad127 (manufactured by IGM Resins) was prepared as the photopolymerization initiator (A). 28 parts by mass of bifunctional urethane acrylate prepolymer UF-8001G (Mw 4500, manufactured by Kyoeisha Chemical Co., Ltd.) was prepared as the urethane-modified acrylate (B). 27 parts by mass of isobornyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) and 5 parts by mass of 2-hydroxyethyl methacrylate (manufactured by Mitsubishi Gas Chemical Company, Inc.) were prepared as the acrylate monomer (C). 5 parts by mass of AEROSIL R972 (manufactured by Nippon Aerosil Co., Ltd.) was prepared as the thixotropy-imparting agent (D). 33 parts by mass of spherical silica KE-S100 (manufactured by Nippon Shokubai Co., Ltd.) was prepared as the additive (E). These were mixed using a planetary centrifugal mixer ARV-310 (Thinky Corporation) until the liquid became homogeneous, yielding a UV-curable adhesive. The resulting UV-curable adhesive was placed in a syringe and degassed under vacuum. The viscosity of the UV-curable adhesive was measured using a rotational viscometer ARG2 (TA Instruments), yielding a value of 18,000 mPa·sec.

[0073] The syringe containing this adhesive was placed in an air pulse type air dispenser SuperΣCMIII (manufactured by Musashi Engineering Co., Ltd.), and 120 degree 2 mg of adhesive was applied to three locations at intervals. 10 seconds after the last application of adhesive, 50 mW of light was irradiated onto the entire lenses 11 and 12 for 300 seconds using an LED area irradiator with a wavelength of 365 nm, thereby obtaining the optical unit 100.

[0074] (evaluation) The viscosity of the UV-curable adhesive before curing was measured using a rotational viscometer ARG2 (manufactured by TA Instruments). The thickness T of each adhesive member 13 was measured using an optical interferometer IRMS8599B (manufactured by Chino Corporation), and the average value was calculated. The elastic modulus E of the adhesive member 13 at -30°C was measured using a low-temperature compatible nanoindenter NanoTestXtreme (manufactured by Nippon Laser Corporation). When the adhesive member 13 was observed from above with a microscope, it was found that the adhesive member 13 was not in contact with the protrusion 125 but was separated from it.

[0075] The fixed position of lens 12 relative to lens 11 was measured in advance at room temperature using an image measuring device NEAIV VHZ-H3030 (manufactured by Nikon Corporation). Then, optical unit 100 was placed in a freezer with an internal temperature of -30°C and left there for 24 hours. After that, optical unit 100 was removed from the refrigerator and returned to room temperature, and then the fixed position of lens 12 relative to lens 11 was measured in the same way using the image measuring device. Then, the change in the fixed position of lens 12 relative to lens 11 was calculated.

[0076] A change in the fixed position of lens 12 relative to lens 11 of less than 10 μm is evaluated as "A," and a change of 10 μm or more is evaluated as "B."

[0077] The measurement result for Example 1 was that the change in the fixing position was 2.9 μm. Because the change in the fixing position for Example 1 was 2.9 μm, the evaluation result was "A."

[0078] [Example 2] In Example 2, a glass lens using optical glass BK7 (manufactured by Ohara Corporation) was prepared as lens 11. Also in Example 2, a resin lens using resin Zeonex E480R (manufactured by Zeon Corporation) was prepared as lens 12. Except for these, optical unit 100 was manufactured under the same conditions as in Example 1.

[0079] The change in the fixing position in Example 2 was 8.1 μm, and therefore the evaluation result was “A.” The reason why the change in the fixing position in Example 2 was larger than in Example 1 is thought to be because the value of α1 / α2 was 0.1, which was smaller than in Example 1.

[0080] [Example 3] In Example 3, the amount of adhesive applied was 5 mg. Also, the adhesive member 13 was made to contact the outer peripheral surface 123 of the lens 12. Except for these, the optical unit 100 was manufactured under the same conditions as in Example 1.

[0081] The change in the fixing position in Example 3 was 6.0 μm, and therefore the evaluation result was “A.” It is believed that the change in the fixing position in Example 3 was reduced by increasing the adhesive area between the adhesive member 13 and the lens 12 compared to Example 2.

[0082] [Example 4] In Example 4, the amount of isobornyl acrylate was 22 parts by mass, and the amount of N,N-dimethylacrylamide (DMAA) (manufactured by KJ Chemicals) was 5 parts by mass. Except for these, the optical unit 100 was produced under the same conditions as in Example 3.

[0083] The change in the fixing position in Example 4 was 5.2 μm, and therefore the evaluation result was “A.” In Example 4, the addition of N,N-dimethylacrylamide to Example 3 improved the adhesive strength compared to Example 3, which is thought to have resulted in a smaller change in the fixing position compared to Example 3.

[0084] [Example 5] In Example 5, UF-8001G and isobornyl acrylate were each 34 parts by mass, AEROSIL R972 was 6 parts by mass, and spherical silica KE-S100 (manufactured by Nippon Shokubai Co., Ltd.) was 14 parts by mass. Except for these, the optical unit 100 was produced under the same conditions as in Example 4.

[0085] The change in the fixing position in Example 5 was 4.2 μm, and therefore the evaluation result was “A.” It is believed that the change in the fixing position in Example 5 was smaller than in Example 4 because the elastic modulus E of the adhesive was smaller.

[0086] [Example 6] In Example 6, UF-8001G and isobornyl acrylate were each 40 parts by mass, and AEROSIL R972 was 8 parts by mass. Furthermore, spherical silica KE-S100 was not added in Example 6. Except for these, the optical unit 100 was produced under the same conditions as in Example 5.

[0087] The change in the fixing position in Example 6 was 1.1 μm, and therefore the evaluation result was “A.” It is believed that the change in the fixing position in Example 6 was smaller than in Example 5 because the elastic modulus E of the adhesive was smaller.

[0088] [Example 7] In Example 7, the diameter of the base material 110 was 45 mm, and the diameter of the base material 120 was 44 mm. Except for this, the optical unit 100 was manufactured under the same conditions as in Example 5.

[0089] The change in the fixing position in Example 7 was 4.7 μm, and therefore the evaluation result was “A.” It is believed that the change in the fixing position in Example 7 was greater than in Example 5 because the diameter of the base material 110 was larger.

[0090] [Example 8] In Example 8, the diameter of the base material 110 was set to 20 mm, and the diameter of the base material 120 was set to 19 mm. Except for this, the optical unit 100 was manufactured under the same conditions as in Example 5.

[0091] The change in the fixing position in Example 8 was 3.2 μm, and therefore the evaluation result was “A.” It is believed that the change in the fixing position in Example 8 was smaller than in Example 5 because the diameter of the base material 110 was smaller.

[0092] [Example 9] In Example 9, the height of the protruding portion 125 of the lens 12 was set to 0.1 mm. Except for this, the optical unit 100 was manufactured under the same conditions as in Example 4.

[0093] The change in the fixing position in Example 9 was 8.2 μm, and therefore the evaluation result was “A.” It is believed that the change in the fixing position in Example 9 was greater than in Example 4 because the thickness T of the adhesive member 13 was smaller.

[0094] [Example 10] In Example 10, UF-8001G and isobornyl acrylate were each used in an amount of 40 parts by mass. In Example 10, AEROSIL R972 was used in an amount of 8 parts by mass. In Example 10, spherical silica KE-S100 was not added. Except for these, the optical unit 100 was produced under the same conditions as in Example 9.

[0095] The change in the fixing position in Example 10 was 1.9 μm, and therefore the evaluation result was “A.” It is believed that the change in the fixing position in Example 10 was smaller than in Example 9 because the elastic modulus E of the adhesive member 13 was smaller.

[0096] [Example 11] In Example 11, the height of the protruding portion 125 of the lens 12 was set to 0.01 mm. Except for this, the optical unit 100 was manufactured under the same conditions as in Example 8.

[0097] The change in the fixing position in Example 11 was 7.9 μm, and therefore the evaluation result was “A.” It is believed that the change in the fixing position in Example 11 was greater than in Example 8 because the thickness T of the adhesive member 13 was smaller.

[0098] [Example 12] In Example 12, the height of the protrusion 125 of the lens 12 was set to 0.01 mm. Except for this, the optical unit 100 was manufactured under the same conditions as in Example 10.

[0099] The change in the fixing position in Example 12 was 3.0 μm, and therefore the evaluation result was “A.” It is believed that the change in the fixing position in Example 12 was large compared to Example 10 because the thickness T of the adhesive member 13 was made smaller.

[0100] [Example 13] In Example 13, a glass lens using optical glass S-FPL53 (manufactured by Ohara Corporation) was prepared as lens 11, and a resin lens using resin Zeonex E48R (manufactured by Zeon Corporation) was prepared as lens 12. Except for these, optical unit 100 was manufactured under the same conditions as in Example 9.

[0101] The change in the fixing position in Example 13 was 4.0 μm, and therefore the evaluation result was “A.” In Example 13, α1 / α2 was larger than in Example 9, which is thought to have reduced the thermal stress at low temperatures and reduced the change in the fixing position.

[0102] [Example 14] In Example 14, the amount of ultraviolet-curable adhesive applied was 2 mg, and the adhesive member 13 was prevented from contacting the outer peripheral surface 123 of the lens 12. Except for this, the optical unit 100 was manufactured under the same conditions as in Example 6.

[0103] The change in the fixing position in Example 14 was 4.2 μm, and therefore the evaluation result was “A.” It is believed that the change in the fixing position in Example 14 was greater than in Example 6 because the contact area of ​​the adhesive member 13 with the lens 12 was narrower.

[0104] [Example 15] In Example 15, UF-8001G and isobornyl acrylate were each used in an amount of 44 parts by mass. Furthermore, in Example 15, AEROSIL R972 was used in an amount of 5 parts by mass. Furthermore, in Example 15, N,N-dimethylacrylamide (DMAA) and spherical silica KE-S100 were not added. Except for these, the optical unit 100 was produced under the same conditions as in Example 6.

[0105] The change in the fixing position in Example 15 was 3.8 μm, and therefore the evaluation result was "A." Furthermore, in Example 15, the absence of N,N-dimethylacrylamide compared to Example 6 is thought to have reduced the adhesive strength, which resulted in a larger change in the fixing position.

[0106] [Comparative Example 1] In Comparative Example 1, UF-8001G was used in an amount of 30 parts by mass, isobornyl acrylate in an amount of 29 parts by mass, and AEROSIL R972 in an amount of 1 part by mass. This resulted in a viscosity of the adhesive of 2000 mPa sec. Except for this, an optical unit 100X was manufactured under the same conditions as in Example 1.

[0107] The change in the fixing position in Comparative Example 1 was 21 μm, and therefore the evaluation result was "B." In Comparative Example 1, the viscosity of the adhesive was 2000 mPa·sec, which was lower than in Example 1, and the adhesive seeped into the gap between protrusion 125 and main surface 111 and came into contact with protrusion 125, forming adhesive portion 131X. As a result, in Comparative Example 1, adhesive portion 131X peeled at the interface, which is thought to be why the change in the fixing position was larger than in Example 1.

[0108] [Example 16] In Example 16, grease was applied to the protrusion 125. Except for this, the optical unit 100 was manufactured under the same conditions as those in Comparative Example 1.

[0109] The change in the fixing position in Example 16 was 2.8 μm, and therefore the evaluation result was “A.” It is believed that in Example 16, the change in the fixing position was smaller than in Comparative Example 1 because the adhesive member 13 was separated from the protrusion 125 by the grease.

[0110] [Example 17] In Example 17, the adhesive was applied and then cured by irradiating it with ultraviolet light one second later. Except for this, the optical unit 100 was manufactured under the same conditions as in Comparative Example 1.

[0111] The change in the fixing position in Example 17 was 2.8 μm, and therefore the evaluation result was “A.” In Example 17, it is thought that the change in the fixing position was smaller than in Comparative Example 1 because the adhesive was cured before it penetrated into the gap between the protruding portion 125 and the main surface 111, causing the adhesive member 13 to move away from the protruding portion 125.

[0112] Comparative Example 2 In Comparative Example 2, a lens 12 was prepared in which the distance B in the radial direction R1 between the outer surface 1252 of the ring-shaped protrusion 125 and the outer peripheral surface 123 of the lens 12 was 0.1 mm. Except for this, the optical unit 100X was manufactured under the same conditions as in Example 1.

[0113] The change in the fixing position in Comparative Example 2 was 22 μm, and therefore the evaluation result was "B." In Comparative Example 2, protrusion 125 was close to outer peripheral surface 123 of lens 12, and the adhesive seeped into the gap between protrusion 125 and main surface 111 and came into contact with protrusion 125, forming adhesive portion 131X. As a result, in Comparative Example 2, adhesive portion 131X peeled off at the interface, which is thought to have resulted in a larger change in the fixing position compared to Example 1.

[0114] The conditions and results of Examples 1 to 17 and Comparative Examples 1 and 2 are shown in the tables of FIGS. 7, 8, and 9. In FIG. 7, "Separated" indicates whether the adhesive members 13 and 13X are separated from the protrusion 125, "O" indicates that they are separated, and "-" indicates that they are not separated. "Adhesive" indicates whether the adhesive members 13 and 13X are in contact with the outer peripheral surface 123 of the lens 12, with "O" indicating that they are in contact and "-" indicating that they are not in contact. "DMAA" indicates whether the adhesive members 13 and 13X contain DMAA, with "O" indicating that they contain it and "-" indicating that they do not contain it. "Viscosity" is the viscosity of the uncured adhesive. "B" is the distance in the radial direction R1 between the outer peripheral surface 123 of the lens 12 and the outer surface 1252 of the protrusion 125. "Protrusion Treatment" indicates whether grease is applied to the protrusion 125, with "Grease" indicating that grease is applied and "-" indicating that grease is not applied. "Irradiation timing" indicates the time, in seconds, after the adhesive was last applied, at which ultraviolet light was irradiated.

[0115] From the above results, it is preferable that the relationship E≦2.3×T+2.5 is satisfied, where E [GPa] is the elastic modulus of the adhesive member 13 under a temperature condition of −30° C., and T [mm] is the thickness of the portion of the adhesive member 13 between the lenses 11 and 12. × It is preferable to satisfy the relationship T-0.08×r+2.5.

[0116] The present invention is not limited to the above-described embodiments, and many modifications are possible within the technical concept of the present invention. Furthermore, the effects described in the embodiments are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments.

[0117] In the above-described embodiment, the optical element of the present invention is applied to an imaging device such as a digital camera and an optical device such as a lens barrel, but the present invention is not limited to this. For example, the optical element of the present invention can be applied to any imaging device or any optical device, such as a smartphone, a tablet PC, a game console, a mobile communication device, a wearable device, or a projector.

[0118] In the above embodiment, a case where the material of the base material 110 is glass and the material of the base material 120 is resin has been described as a suitable example, but the present invention is not limited to this. That is, the present invention is applicable to cases where the linear expansion coefficient of the base material 110 and the linear expansion coefficient of the base material 120 are different. [Explanation of symbols]

[0119] 10... optical element, 11... lens (first transparent member), 12... lens (second transparent member), 13... adhesive member

Claims

1. a first transparent member; a second transparent member having a linear expansion coefficient different from that of the first transparent member; an adhesive member that bonds the second transparent member and the first transparent member, the first transparent member has a first major surface; the second transparent member has a second main surface and a protruding portion that protrudes from the second main surface and contacts the first main surface, and has an outer circumferential surface; the adhesive member is spaced apart from a position where the first main surface and the second main surface contact each other, and contacting the outer peripheral surface and spaced apart from the protrusion; An optical element characterized by:

2. The adhesive member bonds the first main surface and the second main surface.

2. The optical element according to claim 1.

3. the first transparent member includes a first transparent substrate; the second transparent member includes a second transparent substrate; 3. The optical element according to claim 1 or 2.

4. When the linear expansion coefficient of the first transparent substrate is α1 and the linear expansion coefficient of the second transparent substrate is α2, the relationship of α1 / α2≦0.24 is satisfied.

4. The optical element according to claim 3.

5. the first transparent substrate is made of glass; The material of the second transparent substrate is a resin.

5. The optical element according to claim 3 or 4.

6. Further provided is a resin holding member that holds the first transparent member.

6. The optical element according to claim 5.

7. The adhesive member is a cured product of a cross-linked adhesive.

7. The optical element according to claim 1, wherein the first and second optical elements are arranged in a plane parallel to each other.

8. The adhesive member contains N,N-dimethylacrylamide.

8. The optical element according to claim 1, wherein the first and second optical elements are arranged in a plane parallel to each other.

9. When the elastic modulus of the adhesive member under a temperature condition of −30° C. is E [GPa] and the thickness of the adhesive member at a portion between the first transparent member and the second transparent member is T [mm], the relationship E≦2.3×T+2.5 is satisfied.

9. The optical element according to claim 1, wherein the first and second optical elements are arranged in a plane parallel to each other.

10. where E [GPa] is the elastic modulus of the adhesive member under a temperature condition of −30° C., T [mm] is the thickness of the adhesive member at a portion between the first transparent member and the second transparent member, and r [mm] is the radial distance between the central axis of the second main surface and the protruding portion, the relationship E≦2.3×T−0.08×r+2.5 is satisfied.

10. The optical element according to claim 1.

11. T is 0.5 mm or more and 1.1 mm or less, 11. The optical element according to claim 10.

12. the protrusion is one of a plurality of circumferentially spaced protrusions; 12. The optical element according to claim 1.

13. The protrusion is ring-shaped.

12. The optical element according to claim 1.

14. the adhesive member is one of a plurality of adhesive members spaced apart in a circumferential direction; 14. The optical element according to claim 1, wherein the first and second optical elements are arranged in a plane parallel to each other.

15. The housing and and the optical element according to any one of claims 1 to 14, disposed inside the housing. An optical instrument characterized by:

16. the optical device is a lens barrel that is detachable from the imaging device body; 16. The optical instrument according to claim 15.

17. The optical element according to any one of claims 1 to 14, an image sensor that receives light that has passed through the optical element; An imaging device characterized by:

18. a portion of the first transparent member contacts a portion of the second transparent member; supplying adhesive so as to be spaced apart from a position where the first transparent member and the second transparent member contact each other; The adhesive is cured to form an adhesive member that bonds the second transparent member and the first transparent member.

2. A method for manufacturing an optical element, comprising the step of obtaining the optical element according to claim 1 by

19. The first transparent member includes a first transparent substrate made of glass. the second transparent member includes a second transparent base material made of resin, securing the first transparent member to the retaining member by heat staking the retaining member; 19. The method for manufacturing an optical element according to claim 18.

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