Meniscus lens and method for forming antireflection film and ink coating film

Abstract

The invention provides a meniscus lens, an anti-reflection film and a method for forming an ink coating film, which can prevent or suppress annular double images even if the ink coating film is formed after the anti-reflection film is formed. In the meniscus lens (1), a second anti-reflection film (22) is laminated on the surface of a second lens surface (12), and an ink coating film (23) is laminated on the surface of a flange surface (13). The ink coating film (23) covers the entire flange surface (13). Namely, an ink coating film (23) provided on the meniscus lens (1) is laminated on the surface of the flange surface (13) and covers the entire surface of the flange surface (13).

Description

Technical Field

[0001] The present invention relates to a meniscus lens having: a convex first lens surface; a concave second lens surface that is recessed toward the first lens surface; and an annular flange surface that is orthogonal to the optical axis and surrounds the second lens surface from the radially outer side. Further, the present invention relates to a method for forming an antireflection film and an ink coating film on the meniscus lens. Background Art

[0002] A lens unit for a vehicle-mounted camera is described in Patent Document 1. In the lens unit of this document, the first lens closest to the object side is a meniscus lens. The first lens has: a convex first lens surface; a concave second lens surface that is recessed toward the first lens surface; and an annular flange surface that is orthogonal to the optical axis and surrounds the second lens surface from the radially outer side. When viewed from the optical axis direction, the entire flange surface overlaps with the first lens surface.

[0003] In this document, an antireflection film is coated on the second lens surface of the first lens. The antireflection film extends from the second lens surface to the inner peripheral portion of the flange surface. Further, on the flange surface, after coating the antireflection film, ink for light shielding is coated. Therefore, an overlapping portion where the ink coating film overlaps the antireflection film is formed at the inner peripheral portion of the flange surface. Prior Art Documents Patent Documents

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2023-103852 Summary of the Invention

[0005] The inventors have found that when light is irradiated from a light source on the optical axis disposed in front of the first lens surface to the first lens surface of the above-described meniscus lens, a ring-shaped ghost image may be generated.

[0006] In view of the above problems, an object of the present invention is to provide a meniscus lens that can prevent or suppress a ring-shaped ghost image even when an ink coating film is formed after forming an antireflection film. Further, a method for forming an antireflection film and an ink coating film on a meniscus lens that can prevent or suppress the generation of a ring-shaped ghost image is proposed.

[0007] The present inventors have conducted in-depth research and found that the ring-shaped ghost image generated when light is irradiated from a light source on the optical axis to the first lens surface is caused by light incident from the first lens surface being reflected at the inner peripheral portion of the flange surface where the antireflection film and the ink coating film overlap and advancing toward the first lens surface side within the meniscus lens. The present invention has been completed based on the above findings.

[0008] In order to solve the above problems, the meniscus lens of the present invention has: a convex first lens surface; a concave second lens surface that is recessed toward the first lens surface side; and an annular flange surface that is orthogonal to the optical axis and surrounds the second lens surface from the radially outer side. When viewed from the optical axis direction, the flange surface overlaps with the first lens surface. Among them, an antireflection film is provided on the surface of the second lens surface, the antireflection film has an annular end surface that is continuously connected to the flange surface without a step, and an ink coating film is laminated on the surface of the flange surface, and the ink coating film covers the entire surface of the flange surface.

[0009] According to the present invention, an ink coating film is provided on the surface of the flange surface, covering the entire surface of the flange surface. Therefore, in the meniscus lens, there is no overlapping portion where the antireflection film and the ink coating film are sequentially laminated in the optical axis direction on the surface of the flange surface. Therefore, even when light is irradiated from a light source arranged on the optical axis to the first lens surface of the meniscus lens, the light incident from the first lens surface will not be reflected at the inner peripheral edge portion of the flange surface. Therefore, the generation of an annular double image can be prevented or suppressed.

[0010] Next, the present invention provides a method for forming an antireflection film and an ink coating film. The antireflection film and the ink coating film are formed on a meniscus lens having: a convex first lens surface; a concave second lens surface that is recessed toward the first lens surface side; and an annular flange surface that is orthogonal to the optical axis and surrounds the second lens surface from the radially outer side. When viewed from the optical axis direction, the flange surface overlaps with the first lens surface. The method for forming the antireflection film and the ink coating film includes: an antireflection film forming step of holding the meniscus lens by a jig having an annular holding portion, and forming an antireflection film at a position on the flange surface that is closer to the inner peripheral side than the holding portion and on the second lens surface, the holding portion covering the portion of the flange surface that is away from the second lens surface; a grinding step of grinding the flange surface and the antireflection film along the flange surface, removing the portion of the antireflection film laminated on the flange surface, and providing an annular end surface on the antireflection film that is continuously connected to the flange surface without a step; and an ink coating step of performing ink coating on the entire surface of the flange surface.

[0011] According to the present invention, in the antireflection film forming step, a meniscus lens is held by a jig having an annular holding portion that covers a portion of the flange surface that is away from the second lens surface, and an antireflection film is formed at a position on the inner peripheral side of the holding portion in the flange surface and on the second lens surface. Thus, the antireflection film is formed from the second lens surface to the inner peripheral edge portion of the flange surface. Therefore, the second lens surface can be reliably covered by the antireflection film. In the subsequent grinding step, the flange surface and the antireflection film are ground along the flange surface to remove the antireflection film formed on the inner peripheral edge portion of the flange surface, and an annular end surface that is continuously flush with the flange surface is provided on the antireflection film. In the subsequent ink coating step, the entire surface of the flange surface is ink-coated. Therefore, the meniscus lens does not have an overlapping portion where the antireflection film and the ink coating film are laminated in the optical axis direction on the surface of the flange surface. Therefore, even when light is irradiated from a light source disposed on the optical axis to the first lens surface of the meniscus lens, the light incident from the first lens surface is not reflected at the inner peripheral edge portion of the flange surface. Therefore, generation of an annular double image can be prevented or suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is an explanatory diagram of a meniscus lens to which the present invention is applied. Figure 2 is a partially enlarged view of the meniscus lens. Figure 3 is a flowchart of a method for forming an antireflection film and an ink coating film. Figure 4 is an explanatory diagram of a jig used in the antireflection film forming step. Figure 5 is an explanatory diagram of a conventional meniscus lens. Figure 6 is a photograph of a double image generated in a conventional meniscus lens. Figure 7 is a photograph when light is irradiated to the first lens surface of the meniscus lens of this example. Figure 8 is an explanatory diagram of a meniscus lens of Modification 1. Figure 9 is an explanatory diagram of a meniscus lens of Modification 2. Figure 10 is an explanatory diagram of a meniscus lens of Modification 3. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of a meniscus lens to which the present invention is applied will be described with reference to the drawings.

[0014] (Meniscus Lens) Figure 1 is an explanatory diagram of a meniscus lens to which the present invention is applied. Figure 2It is a partial enlarged view of the flange surface of the meniscus lens and the periphery of the second lens surface. Figure 1 The meniscus lens 1 in the illustrated example is used, for example, as the lens closest to the object side of a wide-angle lens unit. The meniscus lens 1 has: a convex first lens surface 11; a concave second lens surface 12 that is recessed toward the first lens surface 11; and an annular flange surface 13 that surrounds the second lens surface 12 from the radially outer side. The flange surface 13 is orthogonal to the optical axis L. The flange surface 13 extends radially outward from the end of the second lens surface 12 on the side opposite to the first lens surface 11.

[0015] In addition, the meniscus lens 1 has an annular surface 14 that connects the outer peripheral end of the first lens surface 11 and the outer peripheral end of the flange surface 13. In the following description, the direction along the optical axis L (optical axis direction) is set as the X-axis direction. In addition, in the X-axis direction, the direction from the first lens surface 11 toward the second lens surface 12 is set as the X1 direction, and the opposite direction is set as the X2 direction. When viewed from the X-axis direction, the entire flange surface 13 overlaps the first lens surface 11.

[0016] On the surface of the first lens surface 11, except for the end portion on the outer peripheral side, a first antireflection film 21 is laminated. In the surface of the first lens surface 11, the end portion where the first antireflection film 21 is not formed is located outside the effective diameter of the first lens surface 11. The first antireflection film 21 has a multilayer structure. That is, the first antireflection film 21 is sequentially laminated on the surface of the first lens surface 11 with: a first refractive index layer having a first refractive index; a second refractive index layer having a second refractive index higher than the first refractive index; and a first refractive index layer having a first refractive index. In addition, on the surface side (the side opposite to the first lens surface 11) of the first refractive index layer that becomes the third layer of the first lens surface 11, a second refractive index layer and a first refractive index layer are alternately laminated. The first antireflection film 21 has an 11-layer structure, and the outermost layer is a first refractive index layer.

[0017] The second anti-reflection film 22 is laminated on the surface of the second lens surface 12. The second anti-reflection film 22 covers the entire surface of the second lens surface 12. The second anti-reflection film 22 has an annular end face 22a that is continuously flush with the flange surface 13 on the inner peripheral side of the flange surface 13. The second anti-reflection film 22 has the same multi-layer structure as the first anti-reflection film 21. That is, the second anti-reflection film 22 is successively laminated on the surface of the second lens surface 12 with: a first refractive index layer having a first refractive index; a second refractive index layer having a second refractive index higher than the first refractive index; and a first refractive index layer having a first refractive index. In addition, a second refractive index layer and a first refractive index layer are alternately laminated in sequence on the surface side (the side opposite to the second lens surface 12) of the first refractive index layer that is the third layer of the second lens surface 12. The second anti-reflection film 22 has an 11-layer structure, and the outermost layer is a first refractive index layer. In this example, the film thickness of the second anti-reflection film 22 is 0.5 μm.

[0018] As Figure 2 shown, an ink coating film 23 is laminated on the surface of the flange surface 13. The ink coating film 23 covers the entire surface of the flange surface 13. In addition, the ink coating film 23 covers the annular end face 22a of the second anti-reflection film 22. Here, the flange surface 13 and the annular end face 22a are not mirror surfaces but rough surfaces. The flange surface 13 and the annular end face 22a of the second anti-reflection film 22 have an arithmetic surface roughness smaller than half of the film thickness of the ink coating film 23. In this example, the film thickness of the ink coating film 23 formed on the flange surface 13 is 20 μm.

[0019] (Method for forming anti-reflection film and ink coating film) Figure 3 is a flowchart of a method for forming the first anti-reflection film 21, the second anti-reflection film 22, and the ink coating film 23 on the meniscus lens 1. Figure 4 is an explanatory diagram of a jig used in the anti-reflection film forming process. As Figure 3 shown, the method for forming the first anti-reflection film 21, the second anti-reflection film 22, and the ink coating film 23 on the meniscus lens 1 successively includes an anti-reflection film forming process ST1, a grinding process ST2, and an ink coating process ST3.

[0020] In the anti-reflection film forming process ST1, first, the jig 50 holds the meniscus lens 1. As Figure 4As shown, the jig 50 has: a first holding portion 51 that holds the end portion on the outer peripheral side of the first lens surface 11; and an annular second holding portion 52 (holding portion) that covers the portion of the flange surface 13 that is separated from the second lens surface 12. Next, in the antireflection film forming step ST1, with the meniscus lens 1 held by the jig 50, a first antireflection film 21 is formed on the inner peripheral side of the first holding portion 51 of the first lens surface 11. In addition, a second antireflection film 22 is formed on the position of the flange surface 13 on the inner peripheral side of the second holding portion 52 and on the second lens surface 12. The first antireflection film 21 is laminated on the surface of the first lens surface 11 by evaporation or sputtering. The second antireflection film 22 is laminated on the surface of the second lens surface 12 and the end portion on the inner peripheral side that is exposed from the jig 50 on the surface of the flange surface 13 by evaporation or sputtering.

[0021] In the grinding step ST2, using a prescribed grinding tool, the entire surface of the flange surface 13 and the second antireflection film 22 are ground along the flange surface 13. As a result, in the second antireflection film 22, the antireflection film portion laminated on the flange surface 13 is removed, and an annular end surface 22a that is continuously flush with the flange surface 13 is provided on the second antireflection film 22. The ground flange surface 13 and the annular end surface 22a of the second antireflection film 22 are not mirror surfaces but rough surfaces. In this example, the arithmetic surface roughness of the flange surface 13 and the annular end surface 22a of the second antireflection film 22 is 10 μm.

[0022] In the ink coating step ST3, the entire surface of the flange surface 13 is ink-coated. In addition, in the ink coating step ST3, the annular end surface 22a of the second antireflection film 22 is ink-coated.

[0023] (Function and effect) Figure 5 It is an explanatory diagram of an existing meniscus lens. Figure 5 The periphery of the flange surface and the second lens surface of the existing meniscus lens is shown enlarged. Figure 6 It is a photograph of a ghost image generated in an existing meniscus lens. Figure 6 It is a view from the second lens surface side observing the state of irradiating light from a light source on the optical axis to the first lens surface of an existing meniscus lens. Figure 7 It is a photograph when observing the state of irradiating light from a light source on the optical axis to the first lens surface 11 of the meniscus lens 1 of this example from the second lens surface 12 side.

[0024] Conventionally, in the method for forming the antireflection film and the ink coating film on the meniscus lens 100, there is no grinding process ST2 between the antireflection film forming process ST1 and the ink coating process ST3. That is, in the existing method for forming the antireflection film and the ink coating film, the antireflection film forming process ST1 and the ink coating process ST3 are continuously performed. Therefore, in the existing meniscus lens 100, at the start time of the ink coating process ST3, the second antireflection film 22 has an antireflection film portion 22b laminated on the surface of the end portion on the inner peripheral side of the flange surface 13. Therefore, when the antireflection film forming process ST1 and the ink coating process ST3 are continuously performed, as Figure 5 shown, the meniscus lens 100 has an overlapping portion 25 where the second antireflection film 22 (antireflection film portion 22b) and the ink coating film 23 are sequentially overlapped from the flange surface 13 side at the inner peripheral edge portion of the flange surface 13.

[0025] For such an existing meniscus lens 100, when light is irradiated from a light source on the optical axis L in front of the first lens surface to the first lens surface, as Figure 6 shown, an annular ghost image 101 is generated.

[0026] Regarding this problem, the inventors intensively studied and obtained the following insight: The annular ghost image 101 generated when light is irradiated from a light source on the optical axis L to the first lens surface 11 is caused by the light incident from the first lens surface 11 being reflected at the inner peripheral edge portion of the flange surface 13 where the second antireflection film 22 and the ink coating film 23 overlap in the optical axis L direction and advancing toward the first lens surface 11 side within the meniscus lens 100.

[0027] Based on such an insight, in the method for forming the antireflection film and the ink coating film in this example, the antireflection film forming process ST1, the grinding process ST2, and the ink coating process ST3 are sequentially included.

[0028] Here, in the antireflection film forming process ST1, the meniscus lens 1 is held by a jig 50. The jig 50 has an annular holding portion that covers the portion of the flange surface 13 that is away from the second lens surface 12. The second antireflection film 22 is formed at a position on the second lens surface 12 and on the inner peripheral side of the second holding portion 52 in the flange surface 13. Thus, the second antireflection film 22 is formed from the second lens surface 12 to the inner peripheral edge portion of the flange surface 13. Therefore, the second lens surface 12 can be reliably covered by the second antireflection film 22.

[0029] In the polishing step ST2 that follows the antireflection film forming step ST1, the flange surface 13 and the second antireflection film 22 are polished along the flange surface 13, and the antireflection film portion 22b of the second antireflection film 22 located on the opposite side of the flange surface 13 in the optical axis L direction with respect to the first lens surface 11 is removed, and a ring-shaped end face 22a that is continuously flush with the flange surface 13 is provided on the second antireflection film 22. Then, in the ink coating step ST3, the entire surface of the flange surface 13 is coated with ink. As a result, in the meniscus lens 1, the second antireflection film 22 is laminated on the surface of the second lens surface 12, and the ink coating film 23 is laminated on the surface of the flange surface 13. The ink coating film 23 covers the entire surface of the flange surface 13.

[0030] In the meniscus lens 1 of this example, an ink coating film 23 is laminated on the surface of the flange surface 13, covering the entire surface of the flange surface 13. Therefore, in the meniscus lens 1, there is no overlapping portion 25 where the second antireflection film 22 and the ink coating film 23 are laminated in sequence in the optical axis L direction on the surface of the flange surface 13. Therefore, even when light is irradiated from a light source disposed on the optical axis L to the first lens surface 11 of the meniscus lens 1, the light incident from the first lens surface 11 will not be reflected at the inner peripheral portion of the flange surface 13. Therefore, as Figure 7 shown, the generation of a ring-shaped double image can be prevented or suppressed.

[0031] In addition, in this example, in the ink coating step ST3, the ring-shaped end face 22a of the second antireflection film 22 is coated with ink. That is, in the meniscus lens 1 of this example, the second antireflection film 22 has a ring-shaped end face 22a that is continuously flush with the flange surface 13, and the ink coating film 23 covers the ring-shaped end face 22a. According to this structure, the ink coating film 23 has an overlapping portion 25 that overlaps with the ring-shaped end face 22a of the second antireflection film 22 in the optical axis L direction on the inner peripheral side of the flange surface 13. However, the overlapping portion 25 is a region with a narrow width corresponding to the thickness of the second antireflection film 22. Therefore, even if the light incident from the first lens surface 11 is reflected at the overlapping portion 25, a ring-shaped double image will not be generated. Here, if the ink coating film 23 reaches the ring-shaped end face 22a, it is possible to prevent the non-coating of ink at the inner peripheral end portion of the flange surface 13. In addition, if the ink coating film 23 covers the ring-shaped end face 22a, it is possible to prevent or suppress the peeling of the second antireflection film 22 from the end portion of the second lens surface 12 on the opposite side of the first lens surface 11.

[0032] In the meniscus lens 1 of this example, the second antireflection film 22 has a multilayer structure, and starting from the second lens surface 12, a first refractive index layer having a first refractive index, a second refractive index layer having a second refractive index, and a first refractive index layer are sequentially stacked, where the second refractive index is higher than the first refractive index. Here, when the second antireflection film 22 has a multilayer structure, each layer of the second antireflection film 22 is likely to peel off on the annular end face 22a that is continuously flush with the flange surface 13. In contrast, as long as the ink coating film 23 covers the annular end face 22a, their peeling can be prevented or suppressed.

[0033] In the meniscus lens 1 of this example, the flange surface 13 and the annular end face 22a are not mirror surfaces but rough surfaces. In this example, the flange surface 13 and the annular end face 22a of the second antireflection film 22 have an arithmetic surface roughness smaller than half of the film thickness of the ink coating film 23. Therefore, ink easily adheres to the flange surface 13 and the annular end face 22a.

[0034] (Modified Example) In addition, in the above example, in the grinding process ST2, the entire surface of the flange surface 13 is ground, but only the end edge portion on the inner peripheral side of the flange surface 13 may be ground to remove the antireflection film portion of the second antireflection film 22 laminated on the flange surface 13.

[0035] Figure 8 It is an explanatory diagram of the meniscus lens 1A of Modified Example 1. Figure 8 It is a partial enlarged view of the periphery of the flange surface 13 and the second lens surface 12 of the meniscus lens 1A of Modified Example 1. In the meniscus lens 1A of this example, the ink coating film 23 does not cover the annular end face 22a of the second antireflection film 22. That is, the ink coating film 23 only covers the flange surface 13. In this case, in the meniscus lens 1A, there is also no overlapping portion 25 where the second antireflection film 22 and the ink coating film 23 are sequentially stacked in the direction of the optical axis L on the surface of the flange surface 13. Therefore, even when light is irradiated from a light source disposed on the optical axis L to the first lens surface 11 of the meniscus lens 1A, the light incident from the first lens surface 11 will not be reflected at the inner peripheral edge portion of the flange surface 13 to generate a double image.

[0036] Figure 9 It is an explanatory diagram of the meniscus lens 1B of Modified Example 2. Figure 9It is a partial enlarged view of the flange surface 13 and the periphery of the second lens surface 12 of the meniscus lens 1B of Modification 2. In the meniscus lens 1B of this example, the ink coating film 23 has a covering portion 23a that covers the end portion of the second antireflection film 22 from the inner peripheral side, and the end portion of the second antireflection film 22 covers the end portion of the second lens surface 12 on the side opposite to the first lens surface 11 in the optical axis L direction. In this way, it is easier to prevent the peeling of the second antireflection film 22. Here, the end portion of the second lens surface 12 on the side opposite to the first lens surface 11 is inclined from the flange surface 13 toward the first lens surface 11 side toward the optical axis L side. Therefore, even if there is a portion where the second antireflection film 22 and the covering portion 23a of the ink coating film 23 overlap at the end portion of the second lens surface 12 on the side opposite to the first lens surface 11, no annular double image is generated due to this structure.

[0037] Figure 10 It is an explanatory view of the meniscus lens 1C of Modification 3. Figure 10 It is a partial enlarged view of the flange surface 13 and the periphery of the second lens surface 12 of the meniscus lens 1C of Modification 3. In the meniscus lens 1C of this example, at the end portion of the second lens surface 12 on the side opposite to the first lens surface 11 in the X-axis direction, there is a cut step portion 15 that is cut away from the optical axis L side (inner peripheral side) and the X1 direction side. In this structure, the second antireflection film 22 covers the surface of the cut step portion 15. In addition, the second antireflection film 22 has an annular end face 22a that is continuously flush with the flange surface 13 at the end portion in the X1 direction. The ink coating film 23 covers the flange surface 13 and the annular end face 22a of the second antireflection film 22.

[0038] The meniscus lens 1C of this example has a cut step portion 15 at a position adjacent to the flange surface 13 on the second lens surface 12. Therefore, it is possible to prevent or suppress the ink coated on the flange surface 13 from dropping into the effective diameter of the second lens surface 12.

[0039] In addition, in the meniscus lens 1C of Modification 3, the ink coating film 23 can also have a covering portion 23a that covers the end portion of the second antireflection film 22 from the inner peripheral side, and the end portion of the second antireflection film 22 covers the end portion of the second lens surface 12 on the side opposite to the first lens surface 11 in the optical axis L direction. In addition, in this example, the ink coating film 23 may not cover the annular end face 22a of the antireflection film. That is, the ink coating film 23 may only cover the flange surface 13.

[0040] Here, the present technology can adopt the following configuration. (1) A meniscus lens having a convex first lens surface, a concave second lens surface that is recessed toward the first lens surface side, and an annular flange surface that is orthogonal to the optical axis and surrounds the second lens surface from the radially outer side. When viewed from the optical axis direction, the flange surface overlaps with the first lens surface. An antireflection film is provided on the surface of the second lens surface. The antireflection film has an annular end face that is continuously flush with the flange surface. An ink coating film is laminated on the surface of the flange surface. The ink coating film covers the entire surface of the flange surface.

[0041] (2) The meniscus lens according to (1), wherein the ink coating film covers the annular end face.

[0042] (3) The meniscus lens according to (2), wherein the antireflection film has a multilayer structure, and on the surface of the second lens surface, there are sequentially laminated: a first refractive index layer having a first refractive index; a second refractive index layer having a second refractive index higher than the first refractive index; and the first refractive index layer.

[0043] (4) The meniscus lens according to (2) or (3), wherein the ink coating film has a covering portion that covers the end portion of the antireflection film from the inner peripheral side, and the end portion of the antireflection film covers the end portion of the second lens surface on the side opposite to the first lens in the optical axis direction.

[0044] (5) The meniscus lens according to any one of (1) to (4), wherein at the end portion of the second lens surface on the side opposite to the first lens surface in the optical axis direction, there is provided a cut step portion that is cut away from the optical axis side and the side opposite to the first lens surface.

[0045] (6) The meniscus lens according to any one of (1) to (5), wherein the flange surface and the annular end face are rough surfaces. Symbolic Explanation

[0046] 1, 1A, 1B, 1C... Meniscus lenses, 11... First lens surface, 12... Second lens surface, 13... Flange surface, 14... Annular surface, 15... Cut step portion, 21... First antireflection film, 22... Second antireflection film, 22a... Annular end face, 23... Ink coating film, 50... Fixture, 51... First holding portion, 52... Second holding portion, 100... Existing meniscus lens.

Claims

1. A meniscus lens comprising: a convex first lens surface; a concave second lens surface that is recessed toward the first lens surface; and an annular flange surface that is orthogonal to the optical axis and surrounds the second lens surface from the radial outside, wherein the flange surface overlaps the first lens surface when viewed from the optical axis direction, characterized in that: An anti-reflection film is provided on the surface of the second lens surface. The anti-reflection film has an annular end surface that is continuous with the flange surface without a step. An ink coating film is laminated on the surface of the flange surface, The ink coating film covers the entire surface of the flange surface.

2. The meniscus lens according to claim 1, characterized in that: The ink coating covers the annular end surface.

3. The meniscus lens according to claim 2, characterized in that: The anti-reflection film has a multilayer structure, wherein a first refractive index layer having a first refractive index, a second refractive index layer having a second refractive index higher than the first refractive index, and the first refractive index layer are sequentially stacked on the surface of the second lens surface.

4. The meniscus lens according to claim 2, characterized in that: The ink coating film includes a covering portion that covers an end portion of the anti-reflection film from an inner peripheral side, and the end portion of the anti-reflection film covers an end portion of the second lens surface on the opposite side to the first lens in the optical axis direction.

5. The meniscus lens according to claim 3, characterized in that: The ink coating film includes a covering portion that covers an end portion of the anti-reflection film from an inner peripheral side, and the end portion of the anti-reflection film covers an end portion of the second lens surface on the opposite side to the first lens in the optical axis direction.

6. The meniscus lens according to claim 1, wherein: A notch step portion cut away from the optical axis side and the side opposite to the first lens surface is provided at an end portion of the second lens surface on the opposite side to the first lens surface in the optical axis direction.

7. The meniscus lens according to claim 1, wherein: The flange surface and the annular end surface are rough surfaces.

8. A method for forming an anti-reflection film and an ink coating, wherein the anti-reflection film and the ink coating are formed on a meniscus lens, wherein the meniscus lens comprises: a convex first lens surface; a concave second lens surface that is recessed toward the first lens surface; and an annular flange surface that is orthogonal to the optical axis and surrounds the second lens surface from the radial outside, wherein the flange surface overlaps with the first lens surface when viewed from the optical axis direction, wherein: have: An anti-reflection film forming step, holding the meniscus lens by a fixture having an annular holding portion, and forming an anti-reflection film on a portion of the flange surface closer to the inner circumference than the holding portion and on the second lens surface, the holding portion covering a portion of the flange surface away from the second lens surface; a grinding step of grinding the flange surface and the anti-reflection film along the flange surface to remove the anti-reflection film portion stacked on the flange surface and providing an annular end surface on the anti-reflection film that is continuous with the flange surface without a step; and In the ink coating step, ink coating is performed on the entire surface of the flange surface.

9. The method for forming an antireflection film and an ink coating according to claim 8, wherein: In the ink coating step, ink coating is performed on the annular end surface of the antireflection film.

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