Manufacturing method of optical element and optical element

Abstract

To provide a technique for shaping a tapered part of a light-blocking film into a desired cross-sectional shape even if both bonding surfaces of a first transparent substrate and a second transparent substrate are flat.SOLUTION: An optical element comprises a transparent body and a light-blocking film provided in the transparent body. The transparent body includes a first transparent substrate and a second transparent substrate, and the first transparent substrate and the second transparent substrate are provided in a prescribed direction so as to hold the light-blocking film therebetween. The light-blocking film includes a tapered part in a desired cross-sectional shape. The first transparent substrate and the second transparent substrate contain the same first glass while the light-blocking film contains second glass. Glass transition point Tg1 of the first transparent substrate and the second transparent substrate is lower than softening point Ts2 of the light-blocking film. The manufacturing method includes heating and deforming the bonding surfaces of the first transparent substrate and the second transparent substrate and welding them in a state where materials of the light-blocking film are held between the flat bonding surface of the first transparent substrate and the flat bonding surface of the second transparent substrate.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an optical element, and to an optical element. [Background technology]

[0002] The optical unit described in Patent Document 1 includes a transparent first substrate, a transparent second substrate, and an aperture formed of black resin that fills the area around the convex portion between the first and second substrates. The first and second substrates are transparent glass substrates or transparent resin substrates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 176704 Summary of the Invention [Problem to be solved by the invention]

[0004] The optical element includes a transparent body and a light-shielding film provided inside the transparent body. The light-shielding film has a flat surface, and when viewed from a predetermined direction perpendicular to the plane (hereinafter simply referred to as the "predetermined direction"), the optical element includes a transmission region that transmits a portion of light and a light-shielding region that blocks another portion of light. The transparent body includes a first transparent substrate and a second transparent substrate, and the first transparent substrate and the second transparent substrate are provided in the predetermined direction with the light-shielding film sandwiched between them and are continuously adjacent to each other in the transmission region.

[0005] The light-shielding film preferably has a tapered portion near the boundary line between the light-shielding region and the light-transmitting region. When the light-shielding film is viewed from a predetermined direction, the greater the distance from the boundary line, the greater the thickness of the tapered portion in the predetermined direction. As a result, the greater the distance from the boundary line in the tapered portion, the lower the light transmittance. Compared to when the light transmittance changes discontinuously at the boundary line, this can suppress light diffraction and the generation of stray light.

[0006] The tapered portion preferably has a desired cross-sectional shape. Specifically, the tip of the tapered portion is in contact with the boundary line, and the distance in the predetermined direction between the tip of the tapered portion and the center of the light-shielding film is preferably 0% to 25% of the maximum thickness of the light-shielding film in the predetermined direction. The cross-sectional shape of the tapered portion has good symmetry, and stress caused by temperature changes in the optical element is small, resulting in minimal warping of the optical element.

[0007] If recesses for accommodating the light-shielding film are formed on the bonding surfaces of both the first and second transparent substrates before bonding the first and second transparent substrates, the tapered portion of the light-shielding film can be adjusted to a desired cross-sectional shape by the recesses. However, forming recesses on the bonding surfaces of both the first and second transparent substrates increases costs.

[0008] An embodiment of the present disclosure provides a technique that can adjust the tapered portion of a light-shielding film to a desired cross-sectional shape even when the bonding surfaces of both the first transparent substrate and the second transparent substrate are flat. [Means for solving the problem]

[0009] A method for manufacturing an optical element according to an embodiment of the present disclosure includes manufacturing an optical element. The optical element includes a transparent body and a light-shielding film disposed inside the transparent body. The light-shielding film has a flat surface, and when viewed from a predetermined direction perpendicular to the flat surface, the optical element includes a transmissive region that transmits a portion of light and a light-shielding region that blocks another portion of the light. The transparent body includes a first transparent substrate and a second transparent substrate, the first transparent substrate and the second transparent substrate are disposed in the predetermined direction with the light-shielding film sandwiched therebetween and continuously contact each other in the transmissive region. The light-shielding film has a tapered portion whose thickness in the predetermined direction increases with increasing distance from a boundary between the light-shielding region and the transmissive region when viewed from the predetermined direction. The tip of the tapered portion is in contact with the boundary, and the distance in the predetermined direction between the tip of the tapered portion and the center of the light-shielding film is 0% to 25% of the maximum thickness T0 of the light-shielding film in the predetermined direction. The first transparent substrate and the second transparent substrate contain the same first glass, and the light-shielding film contains a second glass. The glass transition temperatures Tg1 of the first transparent substrate and the second transparent substrate are lower than the softening point Ts2 of the light-shielding film. The manufacturing method includes: sandwiching a material of the light-shielding film between a flat bonding surface of the first transparent substrate and a flat bonding surface of the second transparent substrate, and thermally deforming and fusing the bonding surfaces of both the first transparent substrate and the second transparent substrate. [Effects of the Invention]

[0010] According to one embodiment of the present disclosure, by setting the glass transition temperature Tg1 of the first transparent substrate and the second transparent substrate lower than the softening point Ts2 of the light-shielding film, even if the joining surfaces of both the first transparent substrate and the second transparent substrate are flat, the first transparent substrate and the second transparent substrate can be thermally deformed and welded together, and the tapered portion of the light-shielding film can be shaped into a desired cross-sectional shape. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1A is a plan view of an optical element according to an embodiment, and FIG. 1B is a cross-sectional view of the optical element according to an embodiment. [Figure 2]FIG. 2(A) is a cross-sectional view showing an example of a tapered portion where ΔT is 0%, FIG. 2(B) is a cross-sectional view showing an example of a tapered portion where ΔT is 25%, and FIG. 2(C) is a cross-sectional view showing an example of a tapered portion where ΔT is 50%. [Figure 3] FIG. 3 shows an example of the relationship between the amount of warpage (relative value) that occurs when an optical element is heated from 25° C. to 100° C. and ΔT. [Figure 4] FIG. 4 is a flowchart illustrating a manufacturing method according to one embodiment. [Figure 5] FIG. 5A is a cross-sectional view showing an example of S101 and S102, FIG. 5B is a cross-sectional view showing an example of S103, and FIG. 5C is a cross-sectional view showing an example of S104. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and their description may be omitted. In the specification, the symbol "to" indicating a numerical range means that the numerical values ​​before and after it are included as the lower and upper limits. The numerical range includes the range rounded up or down.

[0013] An optical element 10 according to one embodiment will be described with reference to FIG. 1. In FIG. 1(B), the direction of the arrow indicates the transmission direction of light LB. The transmission direction of light LB coincides with a predetermined direction (hereinafter also simply referred to as "predetermined direction") perpendicular to the plane 30a of the light-shielding film 30, but may also be oblique to the predetermined direction. In this embodiment, the light LB is visible light, but may also be ultraviolet light or infrared light. The optical element 10 is used, for example, in the optical system of an imaging device.

[0014] As shown in Fig. 1A, when viewed from a predetermined direction, optical element 10 has a transmissive region A1 that transmits a portion of light LB and a light-shielding region A2 that blocks another portion of light LB. Optical element 10 adjusts the shape of light LB using light-shielding region A2. In Fig. 1A, A3 is the boundary between transmissive region A1 and light-shielding region A2 when viewed from the predetermined direction.

[0015] In this embodiment, the shape of the light-shielding region A2 when viewed from a predetermined direction is annular as shown in FIG. 1A, but is not limited to annular. The shape of the light-shielding region A2 when viewed from a predetermined direction may be a rectangular frame shape, a U-shape, or the like. Furthermore, when viewed from a predetermined direction, the light-shielding region A2 is disposed outside the transmission region A1 as shown in FIG. 1A in this embodiment, but may also be disposed inside the transmission region A1.

[0016] 1(B), the optical element 10 includes a transparent body 20 and a light-shielding film 30. The light-shielding film 30 forms a light-shielding region A2 inside the transparent body 20. The light-shielding region A2 is an area where the light-shielding film 30 is provided. The transparent bodies 20 are provided on both the upstream and downstream sides of the light-shielding film 30 in the transmission direction of the light LB.

[0017] The first transparent substrate 21 and the second transparent substrate 22 have bonding surfaces 21a and 22a, respectively, that face each other. The bonding surfaces 21a and 22a have flat surfaces. The flat surfaces of the bonding surfaces 21a and 22a are provided in the transmissive region A1. If the bonding surfaces 21a and 22a have flat surfaces, the first transparent substrate 21 and the second transparent substrate 22 can be uniformly pressed against each other and bonded together in the transmissive region A1. In the transmissive region A1, the bonding surfaces 21a and 22a may be perpendicular to a predetermined direction.

[0018] The first transparent substrate 21 and the second transparent substrate 22 have opposite surfaces 21b and 22b facing opposite to the bonding surfaces 21a and 22a. In this embodiment, both of the opposite surfaces 21b and 22b have flat surfaces, but at least one of them may have a curved surface. The curved surface may be a lens surface, and the optical element 10 may function as a lens. The lens may be any of a plano-convex lens, a biconvex lens, a plano-concave lens, and a biconcave lens.

[0019] The opposite surfaces 21b and 22b may each be a flat surface, a convex curved surface, or a concave curved surface. Any combination of these may be used. For example, one of the opposite surfaces 21b and 22b may be a flat surface and the other may be a convex curved surface or a concave curved surface. Alternatively, one of the opposite surfaces 21b and 22b may be a convex curved surface and the other may be a concave curved surface.

[0020] The first transparent substrate 21 and the second transparent substrate 22 have recesses (also called cavities) 23 on their bonding surfaces 21a, 22a. A light-shielding film 30 is embedded in the recesses 23. As will be described in detail later, before the first transparent substrate 21 and the second transparent substrate 22 are bonded, the bonding surfaces 21a, 22a are flat and do not have the recesses 23. The recesses 23 are formed by thermal deformation of the bonding surfaces 21a, 22a when the first transparent substrate 21 and the second transparent substrate 22 are bonded.

[0021] The first transparent substrate 21 and the second transparent substrate 22 include the same first glass. Generally, glass exhibits smaller changes in optical properties (e.g., refractive index and extinction coefficient) due to temperature changes than resin. The first glass is not particularly limited, but may be, for example, soda-lime glass, alkali-free glass, chemically strengthened glass, borosilicate glass, or lanthanum borate glass.

[0022] The light-shielding film 30 includes a second glass. The content of the second glass in the light-shielding film 30 is 50% by volume or more. When the light-shielding film 30 includes the second glass, the difference in the linear expansion coefficient between the transparent body 20 and the light-shielding film 30 can be made smaller than when the light-shielding film 30 includes only resin. The light-shielding film 30 may be partially crystallized.

[0023] The second glass contained in the light-shielding film 30 may be transparent, in which case the light-shielding film 30 contains a black pigment dispersed in the second glass. The composition of the glass is measured using SEM-EDX. When the light-shielding film 30 contains a black pigment dispersed in transparent glass, the composition of the glass is measured while avoiding the pigment.

[0024] The transparent second glass constituting the light-shielding film 30 is, for example, glass containing SiO2 as its main component, bismuth-based glass, or vanadium-based glass. Bismuth-based glass contains Bi2O3. Vanadium-based glass contains V2O5. Glass containing SiO2 as its main component tends to have a lower refractive index than bismuth-based glass and vanadium-based glass. In this specification, the term "main component" refers to the component that is contained in the largest amount among the components, preferably 50 wt% or more.

[0025] The black pigment constituting the light-shielding film 30 includes, for example, a metal or a metal compound. The metal compound is, for example, an oxide. The metal or metal compound includes at least one element selected from Fe, Cr, Mn, Co, Ni, Ti, and Cu.

[0026] In order to suppress reflection at the interface between the transparent body 20 and the light-shielding film 30, it is preferable to select the second transparent glass constituting the light-shielding film 30 to have a refractive index close to that of the transparent body 20. Therefore, it is preferable that the first glass and the second glass have the same composition.

[0027] The light-shielding film 30 is obtained by firing a paste containing, for example, transparent glass powder and a black pigment. The glass powder is also called glass frit. The paste may contain additives other than the transparent glass powder and the black pigment, such as a resin binder. The resin binder is removed before bonding the first transparent substrate 21 and the second transparent substrate 22 together.

[0028] The second glass may be black instead of transparent, and the light-shielding film 30 may be formed by firing a paste containing black glass powder. Also, the light-shielding film 30 may be a block obtained by molding black molten glass.

[0029] Black glass contains at least one element selected from Fe, Cr, Mn, Co, Ni, Ti, V, and Cu as a coloring component. Black glass may contain, for example, 50% to 75% SiO, 0% to 20% AlO, 0% to 20% NaO, 0% to 20% KO, 0% to 15% MgO, 0% to 20% CaO, 10% to 20% BO, 0% to 20% ΣRO (where R is Mg, Ca, Sr, Ba, or Zn), 0% to 5% ZrO, 1.0% to 14% FeO, 0% to 2% CoO or CoO, and 0% to 0.5% SO. ΣRO is the total content of MgO, CaO, SrO, BaO, and ZnO.

[0030] Black glass may contain at least one selected from V2O5, CrO, MnO, CuO, MoO3, and CeO2, to the extent that the coloring is not impaired. The total content of V2O5, CrO, MnO, CuO, MoO3, and CeO2, expressed in mass % on an oxide basis, is preferably 0% to 3%, and more preferably 0% to 1%.

[0031] The black glass may contain, as a fining agent, at least one selected from SO3, Sb2O3, SnO, Cl, and F, to the extent that the coloring is not impaired. The total content of SO3, Sb2O3, SnO, Cl, and F is preferably 0% to 1%, and more preferably 0% to 0.5%.

[0032] The light-shielding film 30 has a tapered portion 31 near a boundary line A3 between the light-shielding region A2 and the transmission region A1. A tip 31a of the tapered portion 31 contacts the boundary line A3. The tip 31a of the tapered portion 31 may be provided at the interface between the bonding surface 21a of the first transparent base material 21 and the bonding surface 22a of the second transparent base material 22.

[0033] When the light-shielding film 30 is viewed from a predetermined direction, the greater the distance from the boundary line A3, the greater the thickness of the tapered portion 31 in the predetermined direction. As a result, the greater the distance from the boundary line A3 in the tapered portion 31, the lower the transmittance of the light LB. Compared to when the transmittance of the light LB changes discontinuously at the boundary line A3, diffraction of the light LB can be suppressed, and the generation of stray light can be suppressed.

[0034] When the light-shielding film 30 is viewed from a predetermined direction, the tapered portion 31 is provided on at least a part of the boundary line A3, and preferably on the entire boundary line A3. The light-shielding film 30 has a constant thickness portion 32 in addition to the tapered portion 31. The constant thickness portion 32 forms a plane 30a. The constant thickness portion 32 has a constant thickness regardless of the distance from the boundary line A3. The constant thickness portion 32 is positioned farther from the boundary line A3 than the tapered portion 31.

[0035] The transmittance of the light LB at the position where the thickness of the light-shielding film 30 is at its maximum value T0, i.e., at the constant thickness portion 32, is preferably 0.1% or less. This allows the transmission of the light LB to be sufficiently suppressed in the light-shielding region A2, and allows the shape of the light LB to be sufficiently shaped. The maximum thickness T0 of the light-shielding film 30 is set according to the extinction coefficient k of the light-shielding film 30.

[0036] When the extinction coefficient k of the light-shielding film 30 is about 0.01, the maximum value T0 of the thickness T of the light-shielding film 30 is, for example, 20 μm to 50 μm. When the extinction coefficient k of the light-shielding film 30 is about 0.001, the maximum value T0 of the thickness T of the light-shielding film 30 is, for example, 200 μm to 500 μm. When the extinction coefficient k of the light-shielding film 30 is about 0.0003, the maximum value T0 of the thickness T of the light-shielding film 30 is, for example, 800 μm to 1300 μm.

[0037] The extinction coefficient k is measured, for example, with an ellipsometer. The extinction coefficient k can also be calculated using the following formula (1) by exposing the object (for example, the light-shielding film 30) by polishing or the like, measuring the thickness t0 of the object and the transmittance of the object. The thickness t0 of the object is measured, for example, with a micrometer. The transmittance of the object is measured, for example, with a spectrophotometer.

[0038] k=α×λ / 4π (1) In equation (1), α is the absorption coefficient of the object, and λ is the wavelength of the light used to measure the transmittance. The absorption coefficient α is calculated using the following equation (2):

[0039] I = I0 × exp(-α × t0) (2) In equation (2), I0 is the intensity of light immediately after it enters the object from the air, and I is the intensity of light immediately before it leaves the object and enters the air.

[0040] 2, an example of the cross-sectional shape of the light-shielding film 30 will be described. The tip 31a of the tapered portion 31 contacts the boundary line, and the distance ΔT between the tip 31a of the tapered portion 31 and the center of the light-shielding film 30 in a predetermined direction is 0% to 50% of the maximum thickness T0 of the light-shielding film 30 in the predetermined direction.

[0041] If ΔT is 0% to 25% of T0, the cross-sectional shape of the tapered portion has good symmetry, stress caused by temperature changes in the optical element is small, and warping of the optical element is small. ΔT is preferably 0% to 20% of T0, more preferably 0% to 15% of T0, even more preferably 0% to 10% of T0, and particularly preferably 0% to 5% of T0.

[0042] 3 shows an example of the relationship between the amount of warpage (relative value) and ΔT that occurs when the optical element 10 is heated from 25° C. to 100° C. The amount of warpage in FIG. 3 was determined under the following conditions. Thermal stress analysis software: Solidworks Simulation by Dassault Systemes SolidWorks Corporation, Average linear expansion coefficient of transparent body 20: 5.4 x 10 -6 / ℃, Young's modulus of transparent body 20: 70 GPa, Average linear expansion coefficient of light-shielding film 30: 9.4 x 10 -6 , Young's modulus of the light-shielding film 30: 70 GPa, The maximum thickness T0 of the light-shielding film 30 is 0.1 mm. The outer diameter of the annular light-shielding area A2 shown in FIG. 1(A): 40 mm, Inner diameter of the annular light-shielding area A2 shown in FIG. 1(A): 20 mm; The thickness of the flat transparent body 20 shown in FIG. 1(B): 0.3 mm; Distance from boundary line A3 to constant thickness portion 32 shown in FIG. 1(B): 0.5 mm.

[0043] It can be seen from FIG. 3 that if ΔT is 0% to 25% of T0, the amount of warpage can be reduced by half compared to when ΔT is 50% of T0.

[0044] A method for manufacturing an optical element 10 according to one embodiment will be described with reference to Figures 4 and 5. As shown in Figure 4, the manufacturing method includes, for example, steps S101 to S104. Note that the manufacturing method does not necessarily include all of steps S101 to S104. For example, when manufacturing optical elements 10 one by one, step S104 may be omitted. Furthermore, the manufacturing method may include steps other than steps S101 to S104.

[0045] Step S101 includes applying a material 30A of the light-shielding film 30 to at least one bonding surface between the first transparent substrate 21 and the second transparent substrate 22 (the bonding surface 22a of the second transparent substrate 22 in FIG. 5A), as shown in FIG. 5A, for example. The material 30A is, for example, a paste containing glass powder of the second glass. The material 30A may be applied to multiple locations at intervals.

[0046] Material 30A is applied to an area corresponding to light-shielding area A2 (see FIG. 1A), but is not applied to an area corresponding to light-transmitting area A1 (see FIG. 1A). Since material 30A may be spread in step S103, which will be described later, material 30A may be applied away from boundary line A3.

[0047] The coating layer of material 30A has, for example, a tapered portion 31A and a constant thickness portion 32A. Tapered portion 31A corresponds to tapered portion 31 shown in FIG. 1B, and constant thickness portion 32A corresponds to constant thickness portion 32 shown in FIG. 1B.

[0048] The coating layer of material 30A may have only constant thickness portion 32A, and may not have tapered portion 31A. In step S103 described below, tapered portion 31 can be formed by crushing the end of constant thickness portion 32A between first transparent substrate 21 and second transparent substrate 22.

[0049] In step S102, the applied material 30A is heated. Step S102 includes, for example, removing the resin binder contained in the paste. The heating temperature is set to a temperature equal to or higher than the thermal decomposition temperature of the resin binder. Step S102 may or may not include sintering the glass powder. Sintering of the glass powder may be performed in step S103.

[0050] When step S102 includes sintering the glass powder, the heating temperature is set to a temperature equal to or higher than the softening point Ts2 of the light-shielding film 30. If the difference ΔTs (ΔTs = |Ts1 - Ts2|) between the softening point Ts1 of the transparent body 20 and the softening point Ts2 of the light-shielding film 30 is small, the transparent body 20 may deform. By designing the shape and dimensions of the transparent body 20 in anticipation of shape changes during firing, the final target shape and dimensions can be obtained. Alternatively, by firing the paste with the transparent body 20 fitted into a mold, deformation of the transparent body 20 can be suppressed. Alternatively, if a heating method using light such as infrared light is used, the paste containing a pigment has a higher light absorption rate than the transparent body 20, so the paste can be selectively heated, and firing the paste while suppressing deformation of the transparent body 20 is possible.

[0051] When a block obtained by molding black molten glass is used as the material 30A of the light-shielding film 30, steps S101 and S102 are not required.

[0052] Step S103 involves, for example, as shown in Figure 5(B), sandwiching the material 30A of the light-shielding film 30 between the flat bonding surface 21a of the first transparent substrate 21 and the flat bonding surface 22a of the second transparent substrate 22, and thermally deforming and welding the bonding surfaces 21a, 22a of both the first transparent substrate 21 and the second transparent substrate 22.

[0053] The welding temperature is set to a temperature equal to or higher than the glass transition temperature Tg1 of the transparent body 20. During welding, the glasses may be pressed together. In addition to thermocompression bonding between the first transparent substrate 21 and the second transparent substrate 22, thermocompression bonding between the first transparent substrate 21 and the light-shielding film 30 and thermocompression bonding between the second transparent substrate 22 and the light-shielding film 30 are also possible simultaneously. The welding temperature may be +100°C or lower based on the softening point Ts1 of the transparent body 20.

[0054] The glass transition temperature Tg1 of the first transparent substrate 21 and the second transparent substrate 22 is lower than the softening point Ts2 of the light-shielding film 30. As a result, even if the bonding surfaces 21a, 22a of both the first transparent substrate 21 and the second transparent substrate 22 are flat, the first transparent substrate 21 and the second transparent substrate 22 can be thermally deformed and welded together, and the tapered portion 31 of the light-shielding film 30 can be shaped into a desired cross-sectional shape.

[0055] When step S103 includes sintering the glass powder, the welding temperature is set to a temperature approximately equal to the softening point Ts2 of the light-shielding film 30.

[0056] Step S104 includes cutting the bonded body obtained in step S103 into a plurality of optical elements 10, as shown in Fig. 5(C), for example. Cutting includes, for example, blade processing or laser processing.

[0057] Note that if there is a process of applying heat to the glass (for example, baking or fusing the paste), the refractive index of the glass may change and internal stress may be generated, resulting in birefringence. Therefore, the manufacturing method may include heating the glass and slowly cooling it after step S104. This not only restores the refractive index of the glass to the desired value, but also removes internal stress and birefringence.

[0058] The optical element 10 may further include a third transparent substrate (not shown). The first transparent substrate 21, the second transparent substrate 22, and the third transparent substrate are laminated in this order. In this case, the optical element 10 may further include a light-shielding film (not shown) between the second transparent substrate 22 and the third transparent substrate. The light-shielding film (not shown) may be formed in the same manner as the light-shielding film 30.

[0059] [Example] The experimental data will be explained below. In Examples 1 to 3, steps S101 to S104 shown in Figures 4 and 5 were carried out under the same conditions except for the conditions shown in Table 1, and it was investigated whether or not the tapered portion 31 of the light-shielding film 30 could be adjusted to a desired cross-sectional shape (specifically, the cross-sectional shape shown in Figure 2(A)). Example 1 is a comparative example, and Examples 1 and 2 are working examples.

[0060] [Table 1]

[0061] As shown in Table 1, in Example 1, Tg1 was equal to or greater than Ts2, so the viscosity of the light-shielding film was too low in step S104, and it was crushed along the flat bonding surfaces of the first and second transparent substrates. As a result, in Example 1, it was not possible to form a tapered portion with the cross-sectional shape shown in Figure 2(A).

[0062] On the other hand, in Examples 2 and 3, Tg1 was lower than Tg2, so the viscosity of the light-shielding film was appropriately high in step S104, and it was possible to thermally deform the bonding surfaces of both the first transparent substrate and the second transparent substrate. As a result, it was possible to form tapered portions with the cross-sectional shape shown in Figure 2(A) in Examples 2 and 3. Note that the light-shielding film in Example 3 contained a black pigment dispersed in a transparent second glass, and the second glass and the first glass had the same composition.

[0063] The optical element manufacturing method and the optical element according to the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure. [Explanation of symbols]

[0064] 10 Optical Elements 20 Transparent body 21 First transparent base material 22 Second transparent substrate 30 Light-shielding film 31 Tapered portion A1 Transmission region A2 Light-shielding region LB Light

Claims

1. A method for manufacturing an optical element, the method comprising: manufacturing an optical element including a transparent body and a light-shielding film provided inside the transparent body, the method comprising: the light-shielding film has a plane, and when viewed from a predetermined direction perpendicular to the plane, the optical element includes a transmission region that transmits a part of light and a light-shielding region that blocks another part of the light, the transparent body has a first transparent substrate and a second transparent substrate, the first transparent substrate and the second transparent substrate are disposed to sandwich the light-shielding film in the predetermined direction, and are continuously in contact with each other in the transmission region; the light-shielding film has a tapered portion whose thickness in the predetermined direction increases as the distance from the boundary line between the light-shielding region and the light-transmitting region increases when the light-shielding film is viewed from the predetermined direction, a tip of the tapered portion is in contact with the boundary line, and a distance between the tip of the tapered portion and a center of the light-shielding film in the predetermined direction is 0% to 25% of a maximum value T0 of the thickness of the light-shielding film in the predetermined direction; the first transparent substrate and the second transparent substrate include the same first glass, and the light-shielding film includes a second glass; a glass transition temperature Tg1 of the first transparent substrate and the second transparent substrate is lower than a softening point Ts2 of the light-shielding film; The manufacturing method for an optical element includes sandwiching the light-shielding film material between the flat bonding surface of the first transparent substrate and the flat bonding surface of the second transparent substrate, and then thermally deforming and welding the bonding surfaces of both the first transparent substrate and the second transparent substrate.

2. 2. The method for manufacturing an optical element according to claim 1, further comprising the steps of applying a paste containing the second glass to at least one joining surface of the first transparent substrate and the second transparent substrate, and heating the paste, in this order, before thermally deforming and fusing the first transparent substrate and the second transparent substrate.

3. 3. The method for manufacturing an optical element according to claim 1, wherein the first glass and the second glass have the same composition, and the light-shielding film contains a black pigment dispersed in the second glass.

4. An optical element comprising a transparent body and a light-shielding film provided inside the transparent body, the light-shielding film has a plane, and when viewed from a predetermined direction perpendicular to the plane, the optical element includes a transmission region that transmits a part of light and a light-shielding region that blocks another part of the light, the transparent body has a first transparent substrate and a second transparent substrate, the first transparent substrate and the second transparent substrate are disposed to sandwich the light-shielding film in the predetermined direction, and are continuously in contact with each other in the transmission region; the light-shielding film has a tapered portion whose thickness in the predetermined direction increases as the distance from the boundary line between the light-shielding region and the light-transmitting region increases when the light-shielding film is viewed from the predetermined direction, a tip of the tapered portion is in contact with the boundary line, and a distance between the tip of the tapered portion and a center of the light-shielding film in the predetermined direction is 0% to 25% of a maximum value T0 of the thickness of the light-shielding film in the predetermined direction; the first transparent substrate and the second transparent substrate include the same first glass, and the light-shielding film includes a second glass; an optical element, wherein a glass transition temperature Tg1 of the first transparent substrate and the second transparent substrate is lower than a softening point Ts2 of the light-shielding film;

5. 5. The optical element according to claim 4, wherein the first glass and the second glass have the same composition, and the light-shielding film contains a black pigment dispersed in the second glass.

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