Optical element

Abstract

This optical element, when viewed in a transmission direction of light, comprises a transmission region through which a portion of the light passes, and a light-blocking region that blocks another portion of the light. This optical element is provided with a first transparent body, and a light-blocking body that forms the light-blocking region inside the first transparent body. The light-blocking body has a second transparent body formed of the same material as the first transparent body, and a light-blocking film for blocking another part of the light. The light-blocking film is formed over the entire boundary surface between the first transparent body and the light-blocking body.

Description

Optical elements

[0001] The present disclosure relates to optical elements.

[0002] The optical unit described in Patent Document 1 includes a transparent first substrate, a transparent second substrate, and a diaphragm formed of a black resin that fills the periphery of a convex portion between the first substrate and the second substrate. The first substrate and the second substrate are transparent glass substrates or transparent resin substrates.

[0003] International Publication No. 2021 / 176704

[0004] The optical element includes, as viewed from the light transmission direction, a transmission region that transmits a portion of light and a light-shielding region that blocks another portion of the light. The optical element includes a first transparent body and a light-shielding body that forms the light-shielding region inside the first transparent body. When the thickness of the light-shielding body is large, stress caused by the difference in linear expansion coefficient between the light-shielding body and the first transparent body is large, and the durability of the optical element against temperature changes is low.

[0005] One aspect of the present disclosure provides a technique for improving the durability of an optical element against temperature changes.

[0006] An optical element according to one aspect of the present disclosure includes, when viewed from the light transmission direction, a transmission region that transmits a portion of the light and a light-shielding region that blocks another portion of the light. The optical element includes a first transparent body and a light-shielding body that forms the light-shielding region inside the first transparent body. The light-shielding body includes a second transparent body made of the same material as the first transparent body, and a light-shielding film that blocks the other portion of the light. The light-shielding film is formed over the entire boundary surface between the first transparent body and the light-shielding body.

[0007] According to one aspect of the present disclosure, while retaining the function of restricting the passage of light from the first transparent body to the light shielding body across the entire boundary surface between the first transparent body and the light shielding body, the stress caused by the difference in linear expansion coefficient between the first transparent body and the light shielding body can be reduced, thereby improving the durability of the optical element against temperature changes.

[0008] 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. FIG. 2 is a diagram showing an example of the relationship between the stress generated at the boundary line when the optical element is heated from 20° C. to 85° C. and the thickness of the light-shielding body. FIG. 3 is a flowchart showing a method for manufacturing an optical element according to an embodiment. FIG. 4A is a cross-sectional view showing an example of S101, FIG. 4B is a cross-sectional view showing an example of S102, and FIG. 4C is a cross-sectional view showing an example of S103. FIG. 5A is a cross-sectional view showing a first modified example of the optical element, FIG. 5B is a cross-sectional view showing a second modified example of the optical element, FIG. 5C is a cross-sectional view showing a third modified example of the optical element, and FIG. 5D is a cross-sectional view showing a fourth modified example of the optical element. FIG. 6A is a cross-sectional view showing a fifth modified example of the optical element, FIG. 6B is a cross-sectional view showing a sixth modified example of the optical element, and FIG. 6C is a cross-sectional view showing a seventh modified example of the optical element. FIG. 7(A) is a plan view showing an eighth modified example of an optical element, FIG. 7(B) is a plan view showing a ninth modified example of an optical element, FIG. 7(C) is a plan view showing a tenth modified example of an optical element, and FIG. 7(D) is a plan view showing an eleventh modified example of an optical element. FIG. 8 is a flowchart showing a method for manufacturing an optical element according to a twelfth modified example. FIG. 9(A) is a cross-sectional view showing an example of step S201, FIG. 9(B) is a cross-sectional view showing an example of step S202, and FIG. 9(C) is a cross-sectional view showing an example of step S203. FIG. 10(A) is a cross-sectional view showing a thirteenth modified example of an optical element, and FIG. 10(B) is a cross-sectional view showing a fourteenth modified example of an optical element. FIG. 11(A) is a cross-sectional view showing a fifteenth modified example of an optical element, FIG. 11(B) is an enlarged cross-sectional view of region XIB of FIG. 11(A), and FIG. 11(C) is a diagram showing the distribution of light transmittance in region XIB of FIG. 11(A). FIG. 12A is a cross-sectional view showing a sixteenth modification of the optical element, and FIG. 12B is a cross-sectional view taken along line XIIB-XIIB in FIG. 12A.

[0009] 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 range of values ​​means that the values ​​before and after it are included as the lower and upper limits. The range of values ​​includes the range rounded up or down.

[0010] An optical element 10 according to one embodiment will be described with reference to Fig. 1 . In Fig. 1(B), the arrow direction indicates the transmission direction of light LB. Note that the transmission direction of light LB may be the opposite direction to the arrow direction. The transmission direction of light LB is not particularly limited. In this embodiment, 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.

[0011] As shown in Fig. 1A, when viewed from the transmission direction of light LB, optical element 10 includes 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 transmission direction of light LB.

[0012] 1B , the optical element 10 includes a first transparent body 20 and a light blocking body 30. The light blocking body 30 forms a light blocking region A2 inside the first transparent body 20. The light blocking region A2 is an area where the light blocking body 30 is provided. The first transparent bodies 20 are provided on both the upstream and downstream sides of the light blocking body 30 in the transmission direction of the light LB.

[0013] The light blocking body 30 has a second transparent body 31 made of the same material as the first transparent body 20, and a light blocking film 32 that blocks another portion of light. The light blocking film 32 is formed over the entire boundary surface between the first transparent body 20 and the light blocking body 30. While retaining the function of restricting the passage of light from the first transparent body 20 to the light blocking body 30 over the entire boundary surface between the first transparent body 20 and the light blocking body 30, the stress caused by the difference in linear expansion coefficient between the first transparent body 20 and the light blocking body 30 can be reduced, and the durability of the optical element 10 against temperature changes can be improved.

[0014] FIG. 2 shows an example of the relationship between the stress (relative value) generated at the boundary line A3 when the optical element 10 is heated from 25° C. to 85° C. and the thickness T of the light-shielding body 30. In the example of FIG. 2, the light-shielding body 30 is composed of a second transparent body 31 and a light-shielding film 32. In the example of FIG. 2, the thickness t (t<T) of the light-shielding film 32 is constant (0.05 mm). In the comparative example of FIG. 2, the light-shielding body 30 is composed of only the light-shielding film 32. In the comparative example of FIG. 2, the thickness t (t=T) of the light-shielding film 32 is 0.05 mm to 10 mm.

[0015] The analysis conditions for FIG. 2 were as follows: Thermal stress analysis software: Solidworks Simulation manufactured by Dassault Systemes SolidWorks Corporation; Average linear expansion coefficient of the first transparent body 20 and the second transparent body 31: 5.4×10 －６ / °C, Young's modulus of the first transparent body 20 and the second transparent body 31: 70 GPa, Average linear expansion coefficient of the light-shielding film 32: 9.4 × 10 －６ , Young's modulus of the light-shielding film 32: 70 GPa.

[0016] 2, it can be seen that when the light shielding body 30 is composed of the second transparent body 31 and the light shielding film 32, it is possible to reduce the stress caused by the difference in the linear expansion coefficient between the first transparent body 20 and the light shielding body 30, compared to when the light shielding body 30 is composed only of the light shielding film 32. It can be seen that this effect is significantly obtained when the thickness T of the light shielding body 30 is 0.25 mm or more.

[0017] The thickness T of the light shielding body 30 is measured in the transmission direction of the light LB, as shown in Fig. 1. The thickness T of the light shielding body 30 is preferably 0.50 mm or more, more preferably 1.00 mm or more, and even more preferably 5 mm or more. The thickness T of the light shielding body 30 is preferably 50 mm or less, more preferably 30 mm or less, and even more preferably 10 mm or less.

[0018] The shortest distance d (t=d in FIG. 1 ) between the first transparent body 20 and the second transparent body 31 in the transmission direction of the light LB is preferably 0.005 mm or more, more preferably 0.010 mm or more, and even more preferably 0.030 mm or more, from the viewpoint of improving the light blocking property. The distance d is preferably 0.100 mm or less, more preferably 0.080 mm or less, and even more preferably 0.060 mm or less, from the viewpoint of further suppressing the generation of stress caused by the difference in the linear expansion coefficients of the first transparent body 20 and the light blocking body 30.

[0019] 1B , the first transparent body 20 may have a first transparent substrate 21 and a second transparent substrate 22 formed of the same material. The first transparent substrate 21 and the second transparent substrate 22 are disposed on either side of the light blocking body 30 in the transmission direction of the light LB, and are continuously in contact with each other in the transmission region A1. In the transmission region A1, nothing may be present between the first transparent substrate 21 and the second transparent substrate 22. The first transparent substrate 21 and the second transparent substrate 22 are bonded together.

[0020] The first transparent substrate 21 and the second transparent substrate 22 have bonding surfaces 21a and 22a facing each other, respectively. The bonding surfaces 21a and 22a are preferably flat. The flat bonding surfaces 21a and 22a are provided in the transmissive region A1. If the bonding surfaces 21a and 22a are flat, 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.

[0021] 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 constitute 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.

[0022] At least one of the bonding surfaces 21 a and 22 a of the first transparent base material 21 and the second transparent base material 22 may have a recess (also called a cavity) 23. A light blocking body 30 is embedded in the recess 23.

[0023] In this embodiment, the first transparent body 20 is formed by bonding the first transparent base material 21 and the second transparent base material 22 together, but they may not be bonded together. As will be described in detail later, it is also possible to manufacture the optical element 10 by forming a groove on the surface of the first transparent body 20 and embedding the light blocking body 30 in the groove.

[0024] The first transparent body 20 and the second transparent body 31 may be made of the same material, and may be made of the same resin, but are preferably made of the same glass. Glass exhibits smaller changes in optical properties (e.g., refractive index and extinction coefficient) due to temperature changes than resin. The glass is not particularly limited, but examples include soda-lime glass, alkali-free glass, chemically strengthened glass, borosilicate glass, and lanthanum borate glass.

[0025] When the first transparent body 20 and the second transparent body 31 are made of the same glass, it is preferable that the light-shielding film 32 contains glass. This can reduce the difference in linear expansion coefficient between the first transparent body 20 and the light-shielding body 30. The glass content in the light-shielding film 32 is 50% by volume or more. The light-shielding film 32 may be partially crystallized.

[0026] The light-shielding film 32 is a sintered body obtained by firing a paste containing, for example, transparent glass powder and a black pigment. The sintered body contains the black pigment dispersed in the transparent glass. The light-shielding film 32 may also be obtained by molding black molten glass. In other words, the light-shielding film 32 may be formed only from black glass.

[0027] The transparent glass constituting the light-shielding film 32 is, for example, SiO ２ The glass mainly contains Bi, a bismuth-based glass, or a vanadium-based glass. ２ O ３ The vanadium-based glass contains V ２ O ５ Compared with bismuth-based glass and vanadium-based glass, ２ Glasses containing this as a main component tend to have a low refractive index. In this specification, the term "main component" refers to the component that is contained in the largest amount among the components, and is preferably contained in an amount of 50 wt % or more.

[0028] When the light-shielding film 32 is a sintered body obtained by firing a paste containing a transparent glass powder and a black pigment, the black pigment contains, for example, a metal or a metal compound containing at least one element selected from Fe, Cr, Mn, Co, Ni, Ti, and Cu. The metal compound is, for example, an oxide. The paste may contain additives other than the transparent glass powder and the black pigment, such as ceramic powder.

[0029] In order to suppress reflection at the interface between the first transparent body 20 and the light-shielding film 32, it is preferable to select a transparent glass constituting the light-shielding film 32 that has a refractive index close to that of the first transparent body 20. When the light-shielding body 30 contains a black pigment dispersed in transparent glass, it is preferable that the transparent glass constituting the light-shielding film 32 is the same as the glass constituting the first transparent body 20 and the second transparent body 31. The composition of the glass is measured by SEM-EDX. Note that when the light-shielding body 30 contains a black pigment dispersed in transparent glass, the composition of the glass is measured while avoiding the pigment.

[0030] The paste is applied to the first transparent body 20 or the second transparent body 31 and fired. The firing temperature of the paste is set to a temperature equal to or higher than the softening point of the glass that constitutes the paste. If the difference ΔTs (ΔTs = |Ts1 - Ts2|) between the softening point Ts1 of the first transparent body 20 or the second transparent body 31 and the softening point Ts2 of the light-shielding film 32 is small, the first transparent body 20 or the second transparent body 31 may deform during firing. By designing the shape and dimensions of the first transparent body 20 or the second transparent body 31 in anticipation of shape changes during firing, the target shape and dimensions can be finally obtained. Alternatively, the first transparent body 20 or the second transparent body 31 may be fired while the first transparent body 20 or the second transparent body 31 is fitted into a mold, thereby preventing deformation of the first transparent body 20 or the second transparent body 31. Alternatively, if a heating method is used that uses light such as infrared light, the paste containing the pigment has a higher light absorption rate than the first transparent body 20 and the second transparent body 31, so the paste can be selectively heated, and it is possible to bake the paste while minimizing deformation of the first transparent body 20 or the second transparent body 31.

[0031] When the light-shielding film 32 contains black glass, the glass contains, as a coloring component, at least one element selected from, for example, Fe, Cr, Mn, Co, Ni, Ti, V, and Cu. The black glass contains, for example, SiO 2 , as a coloring component, in mass % on an oxide basis. ２ 50% to 75% Al ２ O ３ 0% to 20%, Na ２ O: 0% to 20%, K: ２ O 0% to 20%, MgO 0% to 15%, CaO 0% to 20%, B ２ O ３ 10% to 20%, ΣRO (R is Mg, Ca, Sr, Ba, Zn) 0% to 20%, ZrO ２ 0% to 5%, Fe ２ O ３ 1.0% to 14%, CoO or Co ３ O ４ 0% to 2%, SO ３ ΣRO is the total content of MgO, CaO, SrO, BaO and ZnO.

[0032] Black glass can be V-shaped as long as it does not impair the color. ２ O ５ , CrO, MnO, CuO, MoO ３ and CeO ２ It may contain at least one selected from the following. ２ O ５ , CrO, MnO, CuO, MoO ３ , CeO ２ The total content of is preferably 0% to 3%, more preferably 0% to 1%, expressed in mass % on the oxide basis.

[0033] For black glass, SO 4 is used as a fining agent within the range that does not impair the color. ３ , Sb ２ O ３ , SnO, Cl, and F. ３ , Sb ２ O ３ The total content of SnO, Cl and F is preferably 0% to 1%, more preferably 0% to 0.5%, expressed in mass % on the oxide basis.

[0034] The light-shielding film 32 may be formed by curing a black resin, which is preferably an ultraviolet curable resin.

[0035] A method for manufacturing an optical element 10 according to one embodiment will be described with reference to Figures 3 and 4. As shown in Figure 3, the manufacturing method includes, for example, steps S101 to S103. Note that the manufacturing method does not necessarily include all of steps S101 to S103. For example, if optical elements 10 are manufactured one by one, step S103 may be omitted. Furthermore, the manufacturing method may include steps other than steps S101 to S103.

[0036] Step S101 includes preparing a first transparent substrate 21 and a second transparent substrate 22 that constitute the first transparent body 20, and a light-shielding body 30, as shown in Fig. 4A, for example. Recesses 23 are formed on the bonding surface 21a of the first transparent substrate 21 and the bonding surface 22a of the second transparent substrate 22. The recesses 23 are formed in, for example, a rectangular lattice shape. The light-shielding body 30 includes a second transparent body 31 and a light-shielding film 32. The light-shielding body 30 is formed in, for example, a rectangular lattice shape.

[0037] 4B , step S102 includes bonding the first transparent substrate 21 and the second transparent substrate 22 with the light shielding body 30 sandwiched therebetween. For example, the first transparent substrate 21 and the second transparent substrate 22 are both inserted into the opening of the light shielding body 30, and the first transparent substrate 21 and the second transparent substrate 22 are bonded inside the opening.

[0038] When the first transparent substrate 21 and the second transparent substrate 22 are formed from the same glass, the first transparent substrate 21 and the second transparent substrate 22 can be bonded together by hydrogen bonding between OH groups attached to the glass surfaces, covalent bonds formed by dehydration condensation after the formation of hydrogen bonds, or van der Waals forces between the glass surfaces.

[0039] For example, step S102 includes, in this order, modifying the glass surface by plasma treatment, adding OH groups to the modified surface, stacking the glass pieces with the OH-group-added surfaces facing each other, and heat-treating the stacked glass pieces. The addition of OH groups is performed by supplying pure water or water vapor.

[0040] Alternatively, step S102 may include, in this order, treating the glass surface with an alkaline detergent, washing the surface treated with the alkaline detergent with pure water, stacking the glass pieces with the surfaces washed with pure water facing each other, and heat-treating the stacked glass pieces. Here, treating the glass surface with the alkaline detergent can be omitted.

[0041] Step S102 may include fusing the glass pieces together. The fusing temperature is set to a temperature equal to or higher than the glass transition point of the glass. During fusing, the glass pieces 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 body 30 and thermocompression bonding between the second transparent substrate 22 and the light shielding body 30 are also possible simultaneously.

[0042] When the first transparent substrate 21 and the second transparent substrate 22 are formed of the same resin, the first transparent substrate 21 and the second transparent substrate 22 can be bonded together using a resin adhesive. In this case, an adhesive layer is formed between the bonding surfaces 21 a and 22 a. In addition to bonding the first transparent substrate 21 and the second transparent substrate 22, it is also possible to bond the first transparent substrate 21 and the light shielding body 30 and the second transparent substrate 22 and the light shielding body 30 simultaneously.

[0043] Step S103 includes cutting the bonded body obtained in step S102 into a plurality of optical elements 10, as shown in Fig. 4C, for example. Cutting includes, for example, blade processing or laser processing.

[0044] However, when a process of applying heat to glass (such as baking or fusing a paste) is performed, 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 S103. This allows the refractive index of the glass to return to a desired value, and also removes internal stress and birefringence.

[0045] First to eleventh modified examples of the optical element 10 will be described with reference to Figures 5 to 7. Differences from the above embodiment will be mainly described below. The cross-sectional shape of the light blocking body 30 is rectangular as shown in Figure 1(B) in the above embodiment, but is not limited to a rectangle. The cross-sectional shape of the light blocking body 30 may be a shape combining a rectangle and a semicircle as shown in Figure 5(A), or a shape combining a rectangle and an isosceles triangle as shown in Figure 5(B), for example.

[0046] In other words, in the above embodiment, the light shielding body 30 has only a constant thickness portion as shown in FIG. 1B, but it may have both a constant thickness portion and a tapered portion as shown in FIGS. 5A and 5B, or may have only a tapered portion (not shown). The constant thickness portion is a portion where the thickness T of the light shielding body 30 is constant regardless of the distance from the boundary line A3. The tapered portion is a portion where the thickness T of the light shielding body 30 increases the farther the distance from the boundary line A3. When the light shielding body 30 has a constant thickness portion and a tapered portion, the constant thickness portion is positioned farther from the boundary line A3 than the tapered portion.

[0047] 5(C), not only the first transparent body 20 but also the light blocking body 30 may be formed by bonding multiple parts together. The bonding surfaces 21a, 22a of the first transparent body 20 and the bonding surface of the light blocking body 30 may be disposed on the same plane. In this case, bonding of the multiple parts constituting the first transparent body 20 (e.g., the first transparent base material 21 and the second transparent base material 22) and bonding of the multiple parts constituting the light blocking body 30 can be performed simultaneously.

[0048] 5(D), the first transparent substrate 21 and the second transparent substrate 22 have opposite surfaces 21b and 22b facing away from the bonding surfaces 21a and 22a. The opposite surfaces 21b and 22b may have convex curved surfaces. The convex curved surfaces may be lens surfaces, and the optical element 10 may function as a lens. The lens surfaces may also be concave curved surfaces.

[0049] The opposite surfaces 21b and 22b may each be a flat surface, a convex curved surface, or a concave curved surface. The combinations are arbitrary. 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.

[0050] As shown in Fig. 6(A), only one of the first transparent substrate 21 and the second transparent substrate 22 may be inserted into the opening of the light blocking body 30 and bonded to the other. As described above, as shown in Figs. 1(B) and 4(B), both the first transparent substrate 21 and the second transparent substrate 22 may be inserted into the opening of the light blocking body 30 and the first transparent substrate 21 and the second transparent substrate 22 may be bonded inside the opening.

[0051] 6(B) , the optical element 10 may have a second light-shielding film 40. The second light-shielding film 40 is provided on the surface of the optical element 10, not on the boundary surface between the first transparent body 20 and the light-shielding body 30. For example, when the optical element 10 is viewed from the transmission direction of the light LB, the second light-shielding film 40 is provided on at least a part (preferably the entirety) of the periphery of the optical element 10. The second light-shielding film 40 blocks the transmission of the light LB, similar to the light-shielding film 32. This makes it possible to suppress the generation of stray light.

[0052] 6C , the entire light blocking body 30 may be embedded inside the first transparent body 20, and the surface of the light blocking body 30 may not be exposed to the outside of the optical element 10. In this case, the light blocking film 32 is provided on the entire surface of the second transparent body 31. As described above, the light blocking film 32 may be provided on the entire boundary surface between the first transparent body 20 and the light blocking body 30.

[0053] In the above embodiment, the shape of the light-shielding region A2 as viewed from the transmission direction of the light LB is a rectangular frame as shown in Fig. 1(A), but is not limited to a rectangular frame. The shape of the light-shielding region A2 as viewed from the transmission direction of the light LB may be a shape of two rectangles arranged parallel to each other with a gap as shown in Fig. 7(A), an inverted U-shape as shown in Fig. 7(B), a ring shape as shown in Fig. 7(C), or a circle shape as shown in Fig. 7(D). Note that the cross-sectional view of the optical element 10 shown in Fig. 7(D) is the same as Fig. 6(C).

[0054] The light-shielding area A2 viewed from the transmission direction of light LB may be positioned outside the transmission area A1 as shown in Figures 1(A), 7(A), 7(B) and 7(C), or may be positioned inside the transmission area A1 as shown in Figure 7(D).

[0055] A method for manufacturing an optical element 10 according to a twelfth modification will be described with reference to FIGS. 8 and 9. Differences from the above embodiment and modification will be mainly described below. While the first transparent body 20 in the above embodiment and modification is formed by bonding a first transparent substrate 21 and a second transparent substrate 22 together, the first transparent body 20 in this modification is not bonded together. As shown in FIG. 8, the manufacturing method of this modification includes, for example, steps S201 to S203. Note that the manufacturing method may include steps other than steps S201 to S203.

[0056] Step S201 includes preparing a first transparent body 20 and a second transparent body 31, as shown in Fig. 9A, for example. A groove 24 is formed on the side surface of the first transparent body 20 to accommodate the second transparent body 31. The groove 24 is formed in the shape of, for example, a rectangular frame. The second transparent body 31 is also in the shape of, for example, a rectangular frame, and is divided into four rods in advance.

[0057] 9B, for example, step S202 includes applying a material 32A of the light-shielding film 32 to the groove 24. The material 32A may be any material as long as it has fluidity. The material 32A is not particularly limited, but may be, for example, a paste containing transparent glass and a black pigment, or a black ultraviolet-curable resin.

[0058] 9C , step S203 includes forcing the second transparent body 31 into the groove 24, filling the entire boundary surface between the second transparent body 31 and the first transparent body 20 with a material 32A, and solidifying the filled material 32A to form the light-shielding film 32. The solidification includes sintering or curing. The optical element 10 is obtained by the solidification.

[0059] With reference to Figure 10, thirteenth and fourteenth modified examples of the optical element 10 will be described. Below, differences from the above embodiment and the above modified examples will be mainly described. The light-shielding film 32 is basically formed along the surface of the second transparent body 31 that faces the first transparent body 20. However, as shown in Figures 10(A) and 10(B), the light-shielding film 32 may have a portion 32a that protrudes from the surface of the second transparent body 31 that faces the first transparent body 20. The portion 32a can be formed, for example, by applying the material of the light-shielding film 32 to the first transparent body 20.

[0060] A fifteenth modified example of the optical element 10 will be described with reference to Figure 11. Below, differences from the above embodiment and the above modified examples will be mainly described. When viewed from the transmission direction of light LB, the light blocking body 30 preferably has a region B near the boundary line A3 between the light blocking region A2 and the transmission region A1, where the transmittance of light LB decreases the greater the distance L from the boundary line A3. Compared to a case where the internal transmittance of light LB changes discontinuously at the boundary line A3, this can suppress diffraction of light LB and the generation of stray light. Region B is provided on at least a portion of the boundary line A3, and preferably on the entire boundary line A3.

[0061] If the average extinction coefficient of the light-shielding film 32 in the transmission direction of the light LB is constant regardless of the distance L from the boundary line A3 (for example, if the entire light-shielding film 32 is made of the same material), then the thickness t of the light-shielding film 32 should be increased as the distance L increases to form region B. In this case, it is more preferable that the ratio of the increase Δt in thickness t to the increase ΔL in distance L (Δt / ΔL) increases as the distance L increases, which allows for a gradual change in transmittance.

[0062] To form region B, the average extinction coefficient of the light-shielding film 32 in the transmission direction of light LB may increase as the distance L increases. In this case, the thickness t of the light-shielding film 32 may be constant in region B regardless of the distance L. If the average extinction coefficient increases as the distance L increases, the transmittance of light LB decreases as the distance L increases, even if the thickness t of the light-shielding film 32 is constant. The extinction coefficient is adjusted, for example, by the content of a coloring component (e.g., a black pigment).

[0063] A sixteenth modified example of the optical element 10 will be described with reference to Figure 12. The following mainly describes the differences from the above embodiment and the above modified example. It is preferable that the extinction coefficient of the light LB of the light-shielding film 32 decreases stepwise or continuously from the second transparent body 31 toward the first transparent body 20. This makes it possible to reduce the change in the extinction coefficient at the interface between the light-shielding film 32 and the first transparent body 20, thereby suppressing reflection of the light LB at the interface and preventing the generation of stray light.

[0064] The light-shielding film 32 has, for example, a first layer 33 and a second layer 34 from the second transparent body 31 toward the first transparent body 20. The extinction coefficients of the first transparent body 20 and the second transparent body 31 are smaller than the extinction coefficient of the second layer 34. The extinction coefficient of the second layer 34 is smaller than the extinction coefficient of the first layer 33. As a result, the extinction coefficient of the light-shielding film 32 for the light LB decreases stepwise from the second transparent body 31 toward the first transparent body 20.

[0065] The extinction coefficient is measured, for example, with an ellipsometer. The extinction coefficient can also be calculated using the following formula (1) by exposing the object (for example, the light-shielding film 32) 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.

[0066] 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).

[0067] I=I ０ ×exp(−α×t0) (2) In equation (2), I ０ 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.

[0068] The optical element according to the present disclosure has 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.

[0069] This application claims priority based on Japanese Patent Application No. 2024-031855 filed with the Japan Patent Office on March 4, 2024, the entire contents of which are incorporated herein by reference.

[0070] 10 optical element 20 first transparent body 30 light shielding body 31 second transparent body 32 light shielding film A1 transmission area A2 light shielding area LB light

Claims

1. An optical element comprising, when viewed from the light transmission direction, a transmission region that transmits a portion of the light and a light-shielding region that blocks another portion of the light, the optical element comprising: a first transparent body; and a light-shielding body that forms the light-shielding region inside the first transparent body, the light-shielding body having a second transparent body made of the same material as the first transparent body, and a light-shielding film that blocks the other portion of the light, the light-shielding film being formed over the entire boundary surface between the first transparent body and the light-shielding body.

2. The optical element according to claim 1, wherein the first transparent body has a first transparent substrate and a second transparent substrate formed of the same material, the first transparent substrate and the second transparent substrate being disposed on either side of the light blocking body in the light transmission direction, and being continuously in contact with each other in the transmission region.

3. The optical element according to claim 1 or 2, wherein the thickness of the light blocking body in the light transmission direction is 0.25 mm or more.

4. The optical element according to claim 1 or 2, wherein the first transparent body and the second transparent body are made of the same glass.

5. The optical element according to claim 4, wherein the light-shielding film includes glass.

6. An optical element according to claim 1 or 2, wherein the light blocking body has a region near the boundary line between the light blocking region and the light transmitting region, in which the transmittance of the light decreases the farther the region is from the boundary line.

7. The optical element according to claim 1 or 2, wherein the light-shielding film has an extinction coefficient of light that decreases stepwise or continuously from the second transparent body toward the first transparent body.

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