Optical Elements

Abstract

This optical element has: a transparent base material that allows light to pass therethrough; and a light absorption film that absorbs the light. The transparent base material includes: an optical surface that allows the light to pass from the outside to the inside or from the inside to the outside of the transparent base material or reflects the light from the inside of the transparent base material to the inside; and an adjacent surface adjacent to the optical surface. The light absorption film is formed on the adjacent surface, extends from the adjacent surface to a boundary between the adjacent surface and the optical surface, and is turned around into the optical surface. The optical surface is a plane having the shape of a polygon having four or more sides, and the light absorption film on the optical surface protrudes from the optical surface.

Description

[Technical field]

[0001] The present disclosure relates to optical elements. [Background technology]

[0002] A protective film is formed on the back surface and end surfaces of the cover glass substrate described in Patent Document 1. When printing is performed on the surface of the cover glass, the protective film is configured to come into contact with a positioning member in the printer, thereby protecting the cover glass substrate. After the desired process, the protective film is removed.

[0003] The optical device of Patent Document 2 has an optical element and a lens barrel that holds the optical element therein. The optical element has an optically effective surface and a non-optically effective surface, and has a light-shielding film on at least a part of the non-optically effective surface. The light-shielding film prevents flare from occurring due to internal scattering. When internal scattering occurs, the internal scattering becomes one of the stray lights, which is thought to cause flare. In the optical device of Patent Document 2, the non-optically effective surface of the optical element faces the lens barrel, and further, a part of the light-shielding film of the non-optically effective surface contacts the lens barrel. The optical element is positioned relative to the lens barrel by a part of the light-shielding film contacting the lens barrel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-6745 [Patent Document 2] Japanese Patent Application Publication No. 2017-203951 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, it is necessary to separately prepare a protective film that is not directly related to the product (cover glass substrate), and the protective film must be removed after the desired process, which increases the number of processes.

[0006] In Patent Document 2, the non-optically ineffective surface, which is a non-optical surface, comes into contact with another member. There is no mention of contact with the optical surface or its periphery, nor is there any mention of the presence or absence of a light-shielding film on the optical surface.

[0007] One aspect of the present disclosure provides a technique for suppressing the generation of stray light by using a light absorbing film and preventing defects such as scratches or dirt from occurring on an optical surface. [Means for solving the problem]

[0008] An optical element according to one aspect of the present disclosure includes a transparent substrate that transmits light, a light absorbing film that absorbs the light, and a second light absorbing film that absorbs the light separately from the light absorbing film; The transparent substrate has an optical surface that transmits the light from the outside to the inside or from the inside to the outside of the transparent substrate, or reflects the light from the inside to the inside of the transparent substrate, and an adjacent surface adjacent to the optical surface; A second optical surface that transmits the light from the outside to the inside or from the inside to the outside of the transparent substrate, or reflects the light from the inside to the inside of the transparent substrate, separately from the optical surface; The light absorbing film is formed on the adjacent surface, and extends from the adjacent surface to the optical surface via a boundary between the adjacent surface and the optical surface. The second optical surface is a plane parallel to the optical surface, and a plano-convex lens is provided on the second optical surface. The optical surface is a flat surface of a polygon having four or more sides, the second light absorbing film is formed on the optical surface; The light absorbing film is The second light absorbing film is formed on the second light absorbing film. It protrudes from. Effect of the Invention

[0009] According to one aspect of the present disclosure, the light absorbing film can suppress the generation of stray light and prevent defects from occurring on the optical surface. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view of an optical element according to an embodiment. [Diagram 2] FIG. 2 is a plan view of the optical surface of the optical element of FIG. [Diagram 3] FIG. 3 is a plan view of an optical surface of an optical element according to a first modified example. [Figure 4] FIG. 4 is a cross-sectional view of an optical element according to a second modified example. [Diagram 5]FIG. 5 is a plan view of the optical surface of the optical element of FIG. [Figure 6] FIG. 6 is a cross-sectional view of an optical element according to a third modified example. [Figure 7] FIG. 7 is a cross-sectional view of an optical element according to a fourth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding configurations are denoted by the same reference numerals, and the description may be omitted. In the specification, a numerical range indicated by "~" means that the numerical range includes the numerical values ​​before and after it as the lower and upper limits. In addition, in the specification, "planar view" means a view perpendicular to the first optical surface 31 of the transparent substrate 3.

[0012] An optical element 1 according to this embodiment will be described with reference to FIG. 1 and FIG. 2. The optical element 1 has a transparent substrate 3 and a light absorbing film 5. The transparent substrate 3 transmits light such as visible light. On the other hand, the light absorbing film 5 absorbs light (light such as visible light) that transmits through the transparent substrate 3, and suppresses reflection and / or transmission of light. The reflection of light includes surface reflection and internal reflection. The transmission of light includes the transmission of unexpected light outside the optically effective area. Here, the optically effective area refers to an area through which light necessary for imaging transmits when the optical element 1 is incorporated into an imaging optical system such as a camera. The light absorbing film 5 suppresses the reflection and / or transmission of unintended light, and suppresses the occurrence of stray light. As a result, the occurrence of flare and ghost can be suppressed.

[0013] As shown in FIG. 1, the transparent substrate 3 has a first optical surface 31 and an adjacent surface 32 adjacent to the first optical surface 31. The first optical surface 31 is a flat surface, and transmits light from the outside to the inside of the transparent substrate 3, or from the inside to the outside. The transparent substrate 3 also has a second optical surface 33 in addition to the first optical surface 31. The second optical surface 33 is connected to the first optical surface 31 via the adjacent surface 32. Note that the second optical surface 33 may be connected to the first optical surface 31 via the adjacent surface 32 and a connecting surface 35, as shown in FIG. 6.

[0014] 1, the first optical surface 31 is provided parallel to the second optical surface 33, but may be provided obliquely. In this embodiment, the first optical surface 31 transmits light from the outside to the inside of the transparent substrate 3 or from the inside to the outside, but may reflect light from the inside to the inside of the transparent substrate 3. The first optical surface 31 changes the propagation direction of the light by reflecting the light.

[0015] As shown in FIG. 2, the first optical surface 31 is, for example, a quadrangle in plan view. A quadrangle includes a rectangle and a square. An adjacent surface 32 is adjacent to each of the four sides of the first optical surface 31. The first optical surface 31 is not limited to a quadrangle, and may be a polygon having 5 or more sides. A polygon such as a quadrangle or a pentagon includes a shape with rounded corners. As described above, since the first optical surface 31 is not limited to a quadrangle, the number of adjacent surfaces 32 is also not limited to four.

[0016] A light absorbing film 5 is formed on the adjacent surface 32. The light absorbing film 5 may be formed on one or more adjacent surfaces 32. Depending on the configuration (application) of the transparent substrate 3, the light absorbing film 5 may be formed on the entire adjacent surface 32, or may be formed to have an opening in a part of the adjacent surface 32. However, when the light absorbing film 5 is formed on the adjacent surface 32, it is preferable that the entire periphery of the adjacent surface 32 is covered with the light absorbing film 5. The light absorbing film 5 wraps around from one or more adjacent surfaces 32, through a boundary 34 between the adjacent surface 32 and the first optical surface 31, to the first optical surface 31. The boundary 34 is the periphery 31a of the first optical surface 31.

[0017] The adjacent surface 32 may be a ground surface or a laser processed surface. Specifically, the adjacent surface 32 may be a ground surface obtained by cutting an optical element precursor (optical element material) by grinding with a blade or the like, or may be a laser processed surface obtained by processing the optical element precursor using a laser. When the adjacent surface 32 is a ground surface or a laser processed surface, the generation of stray light can be further suppressed by providing a light absorbing film 5 as described later.

[0018] 1, the adjacent surface 32 is perpendicular to the first optical surface 31, but as will be described later, it may be oblique to the first optical surface 31. Moreover, the adjacent surface 32 is preferably a flat surface as shown in FIG.

[0019] The second optical surface 33 may be a flat surface like the first optical surface 31, and transmits light from the outside to the inside or from the inside to the outside of the transparent substrate 3. In this embodiment, the second optical surface 33 transmits light from the inside to the outside or from the outside to the inside of the transparent substrate 3, but may reflect light from the inside to the inside of the transparent substrate 3. Like the first optical surface 31, the second optical surface 33 changes the propagation direction of light by reflecting light.

[0020] The transparent base material 3 only needs to transmit part of the wavelength band of light used in the optical system (for example, visible light (wavelength 400 nm to 700 nm)), and may reflect or absorb the other part. In other words, the transparent base material 3 may have an optical filter function that reflects or absorbs light in a certain wavelength band. Furthermore, the transparent base material 3 may have a prism function.

[0021] The transparent substrate 3 is composed of, for example, a glass substrate or a resin substrate. The transparent substrate 3 may be plate-shaped or block-shaped (columnar). The glass substrate or the resin substrate may have a reflecting or absorbing function for one or more of infrared rays, visible light, and ultraviolet rays, and may be configured to transmit light of a specific wavelength band. The transparent substrate 3 may have a single-layer structure of a single substrate, or a multi-layer structure in which a film that imparts a reflecting or absorbing function is laminated on a main substrate (glass substrate or resin substrate) to transmit light of a specific wavelength band. In addition, the transparent substrate 3 may be laminated with a film that imparts a function such as antifouling in addition to the reflecting or absorbing function.

[0022] For example, the transparent substrate 3 may further include a resin film or an inorganic film in addition to the glass substrate. The resin film is a film having a function such as a color correction filter, a base film such as a silane coupling agent, or an antifouling film. The resin film is formed by, for example, screen printing, vapor deposition, spray coating, or spin coating. The inorganic film is, for example, a metal oxide film having a function as an optical interference film (antireflection or wavelength selection filter). The inorganic film is formed by, for example, a sputtering method, vapor deposition, or CVD method. The transparent substrate 3 may be a resin substrate.

[0023] The light absorbing film 5 absorbs light transmitted through the transparent substrate 3 and suppresses reflection and / or transmission of the light. When the transparent substrate 3 is used for visible light, the light absorbing film 5 absorbs at least visible light. The light absorbing film 5 preferably absorbs light of all wavelengths from the ultraviolet region to the near infrared region. The light absorbing film 5 has a transmittance of light with a wavelength of 350 to 1000 nm of, for example, 10% or less, preferably 2% or less.

[0024] The light absorbing film 5 suppresses unintended reflection and / or transmission of light, and suppresses the occurrence of stray light. As a result, the occurrence of flare and ghost can be suppressed. The light absorbing film 5 contains, for example, a resin and a light absorbing agent dispersed in the resin. The resin is a photocurable resin, a thermoplastic resin, or a thermosetting resin. The light absorbing agent is an inorganic colorant such as carbon black or titanium black, or an organic colorant.

[0025] The light absorbing film 5 is formed, for example, by applying a resin composition containing a resin and a light absorbing agent, and drying the resin composition. The resin composition is applied to the adjacent surface 32 arranged horizontally facing upward, and then dried. The resin composition may further include a solvent. The solvent is, for example, an organic solvent. The solvent is removed by drying. The resin composition may include a color correction dye, a leveling agent, an antistatic agent, a heat stabilizer, an antioxidant, a dispersant, a flame retardant, a lubricant, or a plasticizer, etc.

[0026] The method for applying the resin composition is, for example, a screen printing method. The screen printing method is suitable for applying the resin composition to a flat surface. The method for applying the resin composition is not limited to the screen printing method. For example, an application method using a dispenser or an inkjet method may be used.

[0027] The light absorbing film 5 is formed on the adjacent surface 32 of the transparent substrate 3, and extends from the adjacent surface 32 through a boundary 34 between the adjacent surface 32 and the first optical surface 31 to the first optical surface 31. Microscopic chips and cracks are likely to be present at the boundary 34 between the adjacent surface 32 and the first optical surface 31. Microscopic chips and cracks are at a level acceptable for a product, and are inevitably included as processing marks. For example, when the adjacent surface 32 is a processed surface obtained by grinding using a blade or the like, or a processed surface obtained by processing using a laser, minute (microscopic) chips and cracks are present at the boundary 34 as processing marks. When internal reflection or transmission of light occurs at the microscopic chips or cracks, stray light is generated.

[0028] According to this embodiment, since the light absorbing film 5 covers the boundary 34, there is almost no internal reflection or transmission of light at the boundary 34. Therefore, even if a microscopic chip or crack occurs at the boundary 34, the occurrence of stray light can be suppressed. As a result, the occurrence of flare and ghosts can be suppressed. In addition, it is possible to suppress the microscopic chip or crack from being seen as an image.

[0029] The light absorbing film 5 is preferably formed in contact with the transparent substrate 3. The light absorbing film 5 is preferably in contact with the transparent substrate 3 at least at the boundary 34, and is preferably in contact with the transparent substrate 3 at the adjacent surface 32. By contacting the transparent substrate 3, the light absorbing film 5 can reduce reflection and can further suppress the occurrence of stray light. If the light absorbing film 5 is not in contact with the transparent substrate 3 and a layer of air or other medium is sandwiched between the light absorbing film 5 and the transparent substrate 3, the number of interfaces increases, and reflection may occur.

[0030] According to this embodiment, as shown in FIG. 1, the first optical surface 31 is a flat surface, and the light absorbing film 5 on the first optical surface 31 protrudes from the first optical surface 31. Therefore, when the optical element 1 is placed on the base 9, a gap can be formed between the first optical surface 31 of the optical element 1 and the flat surface 91 of the base 9, which face each other. As a result, it is possible to prevent the first optical surface 31 of the optical element 1 from being scratched by dust or scratches on the flat surface 91 of the base 9, and to prevent a deterioration in the optical quality of the first optical surface 31. In addition, it is possible to prevent dirt (e.g., dirt of organic components) on the flat surface 91 of the base 9 from adhering to the first optical surface 31 of the optical element 1, and to prevent a deterioration in the optical quality of the first optical surface 31.

[0031] The film thickness T of the light absorbing film 5 on the first optical surface 31 of the transparent substrate 3 is, for example, 0.1 μm to 80 μm, preferably 0.2 μm to 50 μm, and more preferably 0.5 μm to 10 μm. If the film thickness T of the light absorbing film 5 on the first optical surface 31 of the optical element 1 is 0.1 μm or more, a gap of 0.1 μm or more can be formed between the first optical surface 31 of the optical element 1 and the flat surface 91 of the base 9, and the first optical surface 31 can be prevented from being scratched or stained.

[0032] On the other hand, if the thickness T of the light absorbing film 5 on the first optical surface 31 is 80 μm or less, the amount of resin composition applied is small, and the light absorbing film 5 is easily formed only near the periphery 31a of the first optical surface 31. Also, if the thickness T of the light absorbing film 5 on the first optical surface 31 is 80 μm or less, the generation of stray light due to the reflection of light at the end face of the light absorbing film 5 on the first optical surface 31 side can be suppressed. As described above, the first optical surface 31 is a surface that transmits light from the outside to the inside or from the inside to the outside of the transparent substrate 3, or reflects light from the inside to the inside of the transparent substrate 3. Therefore, the light absorbing film 5 is not formed on the entire surface of the first optical surface 31. It is preferable that the light absorbing film 5 is formed only near the periphery 31a of the first optical surface 31.

[0033] The film thickness T of the light absorbing film 5 on the first optical surface 31 is measured, for example, by cross-sectional SEM (Scanning Electron Microscope) observation or the like.

[0034] 2, the light absorbing film 5 on the first optical surface 31 is formed in an annular shape over the entire peripheral edge 31a of the first optical surface 31. The center of gravity P0 of the first optical surface 31 is located inside a frame formed by the light absorbing film 5 on the first optical surface 31. If the center of gravity P0 is located inside the frame, the base 9 can stably support the optical element 1, and a gap can be stably formed between the first optical surface 31 of the optical element 1 and the flat surface 91 of the base 9.

[0035] 3, a gap B in the light absorbing film 5 may be formed along the periphery 31a of the first optical surface 31. For example, the light absorbing film 5 may be formed on two opposing sides of the first optical surface 31, in which case two gaps B in the light absorbing film 5 are formed.

[0036] 3, the number of the gaps B may be one or three or more. For example, the light absorbing film 5 may be formed in a U-shape on three sides of the first optical surface 31, in which case one gap B is formed in the light absorbing film 5.

[0037] When the slits B are formed, it is preferable that the center of gravity P0 of the first optical surface 31 is located inside a frame formed by a straight line L connecting both ends of each slit B and the light absorbing film 5 on the first optical surface 31. If the center of gravity P0 is located inside the frame, the base 9 can stably support the optical element 1, and a gap can be stably formed between the first optical surface 31 of the optical element 1 and the flat surface 91 of the base 9.

[0038] As shown in FIG. 2, the width W of the light absorbing film 5 on the first optical surface 31 is preferably 300 μm or less from the periphery 31a of the first optical surface 31. Since the light absorbing film 5 is formed only near the periphery 31a of the first optical surface 31, the effective area of ​​the first optical surface 31 can be widened. The effective area refers to an area that transmits light or an area that reflects light. W is more preferably 200 μm or less, and further preferably 100 μm or less. Moreover, W is preferably 10 μm or more. W is measured, for example, by a CNC image inspection system (Nikon Corporation's "CNC Image Measuring System NEXIV") or the like.

[0039] The optical element 1 described in this embodiment may be any optical element including a transparent base material that transmits light, and examples thereof include a wavelength-selective optical filter, a polarizing plate, a prism, and a diffraction grating.

[0040] The planar shape of the optical element 1 described in this embodiment is substantially the same as the planar shape of the first optical surface. The planar shape of the optical element 1 may be, for example, a polygon having four or more sides (including a rectangle and a square) in a planar view. Moreover, polygons such as a four or pentagon include shapes with rounded corners. Strictly speaking, since the light absorbing film 5 is formed on the periphery 31a of the first optical surface 31, the planar shape of the optical element 1 and the planar shape of the first optical surface 31 may not be completely the same, but even if there is a slight difference in size, the shapes do not change significantly.

[0041] Next, an optical element 1 according to a second modification will be described with reference to FIG. 4. The following mainly describes the differences between this modification and the above embodiment. The optical element 1 of this modification further includes a second light absorbing film 6. The second light absorbing film 6 is formed on the first optical surface 31 of the transparent substrate 3. The second light absorbing film 6 has a role of an aperture that narrows down light, for example, and spreads to the periphery 31a of the first optical surface 31, and has an opening 61 in the center of the first optical surface 31. Light passes through the opening 61. The shape of the opening 61 may be circular in plan view as shown in FIG. 5, or may be a polygon having four or more sides in plan view. The shape of the opening 61 depends on the optical system or optical device in which the optical element is incorporated.

[0042] The second light absorbing film 6 absorbs at least visible light, similar to the light absorbing film 5. The second light absorbing film 6 may be an absorbing film similar to the light absorbing film 5, and contains, for example, a resin and a light absorbing agent dispersed in the resin. The second light absorbing film 6 is formed, for example, by applying a resin composition containing a resin and a light absorbing agent and drying it.

[0043] The second light absorbing film 6 may be formed of a material or by a method different from those of the light absorbing film 5. In addition, the second light absorbing film 6 may be formed by a sputtering method or the like using a compound containing a metal oxide such as chromium oxide, titanium oxide, or copper oxide.

[0044] The second light absorbing film 6 is formed prior to the light absorbing film 5, and spreads to the peripheral edge 31a of the first optical surface 31. After the formation of the second light absorbing film 6, the light absorbing film 5 is formed. The light absorbing film 5 is formed on the adjacent surface 32 of the transparent substrate 3, and extends from the adjacent surface 32 through the boundary 34 between the adjacent surface 32 and the first optical surface 31, and wraps around to the first optical surface 31. As shown in FIG. 4, the light absorbing film 5 is formed by wrapping around the second light absorbing film 6 that spreads to the peripheral edge 31a of the first optical surface 31.

[0045] The light absorbing film 5 is formed only near the periphery 31a of the first optical surface 31, and is away from the opening 61 of the second light absorbing film 6. The resin composition that is the material of the light absorbing film 5 does not flow into the opening 61. The light absorbing film 5 is not in contact with the first optical surface 31, and is formed on the second light absorbing film 6 and protrudes from the second light absorbing film 6.

[0046] 4, the light absorbing film 5 on the first optical surface 31 protrudes from the second light absorbing film 6. Therefore, when the optical element 1 is placed on the base 9, a gap can be formed between the second light absorbing films 6 of the optical elements 1 facing each other and the flat surface 91 of the base 9. As a result, it is possible to prevent the second light absorbing film 6 from being scratched or stained due to dust, scratches, organic stains, or the like on the flat surface 91 of the base 9, and thus it is possible to prevent deterioration in the optical quality of the second light absorbing film 6.

[0047] Moreover, according to this modification, the region of the second light absorbing film 6 where the light absorbing film 5 overlaps is doubly shielded, improving the light shielding property. In particular, this is preferable because the light shielding property in the vicinity of the boundary 34 of the first optical surface 31 is improved and stray light is suppressed. Furthermore, when there is a defect such as a pinhole in the vicinity of the boundary 34 of the second light absorbing film 6, the light absorbing film 5 can cover the pinhole, which is preferable.

[0048] According to this modification, similarly to the above embodiment, the light absorbing film 5 on the first optical surface 31 protrudes from the first optical surface 31. Therefore, similarly to the above embodiment, it is possible to prevent the first optical surface 31 from being scratched or soiled, and it is possible to prevent deterioration in the optical quality of the first optical surface 31.

[0049] Next, an optical element 1 according to a third modified example will be described with reference to Fig. 6. The following mainly describes the differences between this modified example and the above embodiment. The adjacent surface 32 of the transparent base material 3 in this modified example is inclined with respect to the first optical surface 31. The adjacent surface 32 is a chamfered surface, and the angle α between the adjacent surface 32 and the first optical surface 31 is an obtuse angle.

[0050] If the angle α between the adjacent surface 32 and the optical surface 31 is an obtuse angle, damage due to contact with other members can be suppressed, and operational safety in handling the product can be improved.

[0051] The method of forming the adjacent surface 32, which is a chamfered surface, is not particularly limited, and can be formed by, for example, grinding or polishing. In this case, the chamfered surface is a ground or polished surface. In the case of grinding or polishing, microscopic chips or cracks may exist on the chamfered surface, but by providing the light absorbing film 5 as in the above embodiment, the generation of stray light caused by microscopic chips or cracks can be suppressed.

[0052] The surface roughness of adjacent surface 32, which is a chamfered surface, may be rougher than the surface roughness of first optical surface 31. The surface roughness is the arithmetic mean roughness Ra as defined in Japanese Industrial Standards JIS B 0601:2013. The rougher the surface roughness of adjacent surface 32, the more effectively it can suppress stray light.

[0053] The transparent substrate 3 has a connecting surface 35 that is connected to the first optical surface 31 via an adjacent surface 32 that is a chamfered surface. The connecting surface 35 is perpendicular to the first optical surface 31 in FIG. 6, but may be oblique. The angle between the connecting surface 35 and the adjacent surface 32 may be an obtuse angle. The connecting surface 35 may be a flat surface.

[0054] When the light absorbing film 5 is formed, the flow of the resin composition may flow from the adjacent surface 32 to the connecting surface 35. That is, the light absorbing film 5 may flow to the connecting surface 35 via the boundary between the adjacent surface 32 and the connecting surface 35. The light absorbing film 5 may also be formed on the connecting surface 35. By providing the light absorbing film 5 on the connecting surface 35 side as well, it is possible to suppress the generation of stray light caused by microscopic chips and cracks.

[0055] Next, an optical element 1 according to a fourth modified example will be described with reference to Fig. 7. The following mainly describes the differences between this modified example and the above embodiment. The optical element 1 of this modified example has a lens 4 formed on a transparent substrate 3. The lens 4 is formed on a second optical surface 33 of the transparent substrate 3.

[0056] The lens 4 includes a peripheral portion 41 and a lens surface 42 surrounded by the peripheral portion 41. The lens surface 42 is a curved surface that bends the propagation direction of light. The lens surface 42 focuses or diverges light.

[0057] The lens surface 42 of the lens 4 is surrounded by a peripheral portion 41 that is annular in plan view. Specifically, in plan view, the peripheral portion 41 is annular, and the lens surface 42 is circular. Note that, in plan view, the peripheral portion 41 may be polygonal annular, and the lens surface 42 may be polygonal. The polygonal shape includes a shape with rounded corners.

[0058] 7, the lens 4 is, for example, a convex lens, more specifically, a plano-convex lens. The lens 4 has a flat surface 43 facing opposite to the lens surface 42, and is laminated with the flat surface 43 facing the second optical surface 33 of the transparent substrate 3.

[0059] 7, the lens 4 is a plano-convex lens, but may be a plano-concave lens. In the latter case, the lens 4 also has a flat surface 43 facing away from the lens surface 42, and is laminated with the flat surface 43 facing the second optical surface 33 of the transparent substrate 3.

[0060] The lens 4 may be an aspheric lens or a spherical lens.

[0061] The lens 4 is obtained, for example, by molding a resin composition using a molding die (not shown). The molding die has a concave-convex pattern that is an inverse of the concave-convex pattern of the lens 4. The molding die may be a metal mold or a replica of a metal mold. The replica is obtained by transferring the concave-convex pattern of the metal mold an even number of times.

[0062] The resin composition of the lens 4 is, for example, a photocurable resin. The photocurable resin is cured by irradiation with light such as ultraviolet light. As the photocurable resin, an epoxy resin, a silicone resin, an acrylic resin, or the like is used.

[0063] The resin composition is not limited to a photocurable resin, and may be a thermosetting resin, etc. The thermosetting resin is cured by heating. Examples of the thermosetting resin include a silicone resin, an epoxy resin, and a phenol resin.

[0064] Unlike thermosetting resins, photocurable resins can be cured at room temperature, which can prevent a decrease in dimensional accuracy due to the difference in thermal expansion with the transparent substrate 3. Therefore, photocurable resins can be applied easily over a large area compared to thermosetting resins. Also, unlike thermosetting resins, photocurable resins do not require a thermal process, which shortens the lead time and improves productivity.

[0065] On the other hand, thermosetting resins have superior heat resistance after curing and superior reflow resistance after curing, compared to photocurable resins.

[0066] The resin composition may be applied to the surface of a molding die or to the surface of the transparent substrate 3. The resin composition is applied, for example, by a dispenser. The dispenser can finely adjust the amount of resin composition applied. The amount of resin composition applied is set according to the shrinkage rate of the resin composition when cured and the volume of the lens 4 made of the cured resin composition. The method of applying the resin composition is not particularly limited.

[0067] The resin composition is solidified on the transparent substrate 3. In this specification, solidification includes curing. When the resin composition is a photocurable resin, the photocurable resin is cured by irradiation with light such as ultraviolet light. The light may be irradiated onto the resin composition through the transparent substrate 3, may be irradiated onto the resin composition through the molding die, or may be irradiated onto the resin composition through both the transparent substrate 3 and the molding die.

[0068] On the other hand, when the resin composition is a thermosetting resin, the thermosetting resin is cured by heating. The heater may heat the resin composition through the transparent substrate 3, may heat the resin composition through the mold, or may heat the resin composition through both the transparent substrate 3 and the mold.

[0069] The lens 4 may be molded on the transparent substrate 3, or may be molded from a substrate separate from the transparent substrate 3 and then bonded to the transparent substrate 3 via a bonding layer (not shown). In the latter case, the optical element 1 includes, in addition to the transparent substrate 3 and the lens 4, a bonding layer (not shown).

[0070] The bonding layer bonds the transparent substrate 3 and the lens 4. For example, an OCA (Optical Clear Adhesive) double-sided tape is used as the bonding layer. Instead of the double-sided tape, a liquid adhesive or the like may be used.

[0071] In this embodiment, the transparent substrate 3 and the lens 4 are made of different materials, but they may be made of the same material. In the latter case, the transparent substrate 3 and the lens 4 may be molded integrally at the same time by injection molding or the like. The material for injection molding is a resin, more specifically, a thermoplastic resin.

[0072] Furthermore, the transparent substrate 3 and the lens 4 may be made of glass. For example, a preform material that is a precursor of the lens 4 may be prepared on the transparent substrate 3, and the lens 4 may be molded by a heat press method.

[0073] This modification is not limited to the configuration in Fig. 7, and can be combined with the second and third modifications to produce the same effect. That is, a lens may be formed on a transparent substrate having a second light absorbing film, or a lens may be formed on a transparent substrate having a chamfered surface.

[0074] Although the optical element according to the present disclosure has been described above, the present disclosure is not limited to the above-mentioned 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.

[0075] This application claims priority based on Japanese Patent Application No. 2020-145759, filed with the Japan Patent Office on August 31, 2020, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0076] 1 Optical elements 3 Transparent base material 31 1st optical surface (optical surface) 32 Adjacent Surface 33 Second optical surface 34 Boundary 5. Light absorbing film

Claims

1. A transparent substrate that transmits light; a light absorbing film that absorbs the light; a second light absorbing film that absorbs the light separately from the light absorbing film; the transparent substrate includes an optical surface that transmits the light from the outside to the inside or from the inside to the outside of the transparent substrate, or reflects the light from the inside to the inside of the transparent substrate, an adjacent surface adjacent to the optical surface, and a second optical surface that is separate from the optical surface and transmits the light from the outside to the inside or from the inside to the outside of the transparent substrate, or reflects the light from the inside to the inside of the transparent substrate, the light absorbing film is formed on the adjacent surface, and extends from the adjacent surface to the optical surface via a boundary between the adjacent surface and the optical surface; the second optical surface is a plane parallel to the optical surface, and a plano-convex lens is provided on the second optical surface; an optical element, wherein the optical surface is a flat surface of a polygon having four or more sides, the second light absorbing film is formed on the optical surface, and the light absorbing film is formed on the second light absorbing film and protrudes from the second light absorbing film.

2. The optical element according to claim 1 , wherein the light absorbing film on the optical surface is formed in an annular shape around the entire periphery of the optical surface.

3. a gap is formed in the light absorbing film along a periphery of the optical surface, The optical element according to claim 1 , wherein the center of gravity of the optical surface is located inside a frame formed by a straight line connecting both ends of each of the slits and the light absorbing film on the optical surface.

4. The optical element according to any one of claims 1 to 3, wherein the adjacent surfaces are flat.

5. 5. The optical element according to claim 1, wherein the light absorbing film is in contact with the adjacent surface.

6. 6. The optical element according to claim 1, wherein a width of the light absorbing film on the optical surface is 300 μm or less from a periphery of the optical surface.

7. 7. The optical element according to claim 1, wherein the light absorbing film on the optical surface has a thickness of 0.1 μm to 80 μm.

8. 8. The optical element according to claim 1, wherein the second light absorbing film has an opening in the center.

9. 9. The optical element according to claim 1, wherein the adjacent surfaces are ground surfaces or laser processed surfaces.

10. 9. The optical element according to claim 1, wherein the adjacent surfaces are chamfered surfaces, and an angle between the adjacent surfaces and the optical surface is an obtuse angle.

11. The optical element according to claim 10 , wherein the chamfered surface is a ground surface or a polished surface.

12. a connecting surface that is connected to the optical surface via the chamfered surface, the connecting surface being a flat surface; The optical element according to claim 10 , wherein the light absorbing film extends around the connecting surface via a boundary between the adjacent surface and the connecting surface.

13. The optical element according to any one of claims 1 to 12, wherein the transparent base material is in the form of a plate or a block.

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