Meniscus lens, antireflection film, and formation method of black coating film

Abstract

To provide a meniscus lens capable of suppressing or preventing a ring-shaped ghost even when a black coating film is formed after formation of an antireflection film.SOLUTION: In a meniscus lens 1, a second antireflection film 22 is laid on a surface of a second lens face 12, and a black coating film 23 is laid on a surface of a flange face 13. The black coating film 23 covers the whole of the flange face 13, namely, the black coating film 23 provided to the meniscus lens 1 is laid on the surface of the flange face 13 so as to cover the whole of the flange face 13.SELECTED DRAWING: Figure 2

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 on the side of 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. The present invention also relates to a method for forming an antireflection film and an ink coating film on such a meniscus lens.

[0002] A lens unit for an in-vehicle camera is described in Patent Document 1. In the lens unit of this document, the first lens located 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 on the side of 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 applied to the second lens surface of the first lens. The antireflection film extends from the second lens surface to the inner peripheral edge portion of the flange surface. Further, an ink for light shielding is applied to the flange surface after the application of the antireflection film. Therefore, an overlapping portion is formed on the inner peripheral edge portion of the flange surface, where the ink coating film overlaps the antireflection film.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inventors have found that when light rays are irradiated from a light source arranged on the optical axis in front of the first lens surface toward the first lens surface with respect to the above-described meniscus lens, a ring-shaped ghost may occur.

[0006] In view of the above problems, an object of the present invention is to provide a meniscus lens capable of preventing or suppressing ring-shaped ghosts even when an ink coating film is formed after forming an antireflection film. Another object is to propose a method for forming an antireflection film and an ink coating film on a meniscus lens capable of preventing or suppressing the occurrence of ring-shaped ghosts.

Means for Solving the Problems

[0007] As a result of intensive studies by the inventors, it has been found that the ring-shaped ghosts generated when light rays are irradiated from a light source arranged on the optical axis toward the first lens surface are caused by the light rays incident from the first lens surface reflecting at the inner peripheral edge portion of the flange surface where the antireflection film and the ink coating film overlap and then traveling inside the meniscus lens toward the side of the first lens surface. The present invention is based on such 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 on the side of 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 in the optical axis direction, in the meniscus lens where the flange surface overlaps 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 continuous with the flange surface without a step. 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, the ink coating film is provided on the surface of the flange surface and covers 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 laminated in this order in the optical axis direction on the surface of the flange surface. Thus, even when light rays are irradiated from a light source arranged on the optical axis toward the first lens surface with respect to the meniscus lens, the light rays incident from the first lens surface do not reflect at the inner peripheral edge portion of the flange surface. Therefore, the occurrence of ring-shaped ghosts can be prevented or suppressed.

[0010] Next, the present invention has a convex first lens surface, a concave second lens surface that is recessed on the side of 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, in a method for forming an antireflection film and an ink coating film on a meniscus lens in which the flange surface overlaps the first lens surface, the meniscus lens is held by a jig having an annular holding portion that covers a portion of the flange surface that is separated from the second lens surface. An antireflection film forming step of forming an antireflection film on the inner peripheral side of the holding portion and on the second lens surface on the flange surface; a polishing step of polishing the flange surface and the antireflection film along the flange surface, removing the antireflection film portion laminated on the flange surface, and providing an annular end surface that is continuous without a step on the flange surface on the antireflection film; and an ink coating step of performing ink coating on the entire surface of the flange surface. It is characterized by comprising.

[0011] According to the present invention, in the antireflection film forming step, the meniscus lens is held by a jig having an annular holding portion that covers a portion of the flange surface that is separated from the second lens surface, and an antireflection film is formed on the inner peripheral side of the second holding portion and on the second lens surface on the flange surface. As a result, 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 surely covered by the antireflection film. In the subsequent polishing step, the flange surface and the antireflection film are polished 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 continuous without a step on the flange surface is provided on the antireflection film. In the ink coating step performed thereafter, ink coating is applied to the entire surface of the flange surface. Therefore, the meniscus lens does not have an overlapping portion on the surface of the flange surface where the antireflection film and the ink coating film are laminated in this order in the optical axis direction. Therefore, even when light rays are irradiated from a light source arranged on the optical axis toward the first lens surface with respect to the meniscus lens, the light rays incident from the first lens surface do not reflect at the inner peripheral edge portion of the flange surface. Therefore, it is possible to prevent or suppress the occurrence of a ring-shaped ghost.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

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

[0014] (Meniscus Lens) FIG. 1 is an explanatory view of a meniscus lens to which the present invention is applied. FIG. 2 is a partially enlarged view of the flange surface of the meniscus lens and the periphery of the second lens surface. The meniscus lens 1 in this example shown in FIG. 1 is used, for example, as a lens located on the object side most 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 on the side of 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] Further, 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 taken as the X-axis direction. Also, in the X-axis direction, the direction from the first lens surface 11 toward the second lens surface 12 is taken as the X1 direction, and the opposite direction is taken as the X2 direction. When viewed from the X-axis direction, the entire flange surface 13 overlaps with 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 thereof, a first antireflection film 21 is laminated. On the surface of the first lens surface 11, the end portion where the first antireflection film 21 is not formed is 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 includes 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, which are laminated on the surface of the first lens surface 11 in this order. Also, on the surface side (the side opposite to the first lens surface 11) of the first refractive index layer that is the third layer of the first lens surface 11, a second refractive index layer and a first refractive index layer are alternately laminated in this order. The first antireflection film 21 has an 11-layer structure, and the outermost layer is a first refractive index layer.

[0017] A 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 continuous with the flange surface 13 without a step on the inner peripheral side of the flange surface 13. The second anti-reflection film 22 has a multi-layer structure similar to that of the first anti-reflection film 21. That is, the second anti-reflection film 22 includes 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, which are laminated on the surface of the second lens surface 12 in this order. Further, 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, a second refractive index layer and a first refractive index layer are alternately laminated in this order. 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 shown in FIG. 2, 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. Further, 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 1 / 2 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) FIG. 3 is a flowchart of a forming 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. FIG. 4 is an explanatory diagram of a jig used in the anti-reflection film forming step. As shown in FIG. 3, the forming 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 includes an anti-reflection film forming step ST1, a polishing step ST2, and an ink coating step ST3 in this order.

[0020] In the antireflection film forming step ST1, first, the meniscus lens 1 is held by the jig 50. As shown in FIG. 4, the jig 50 includes 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 a portion spaced apart from the second lens surface 12 on the flange surface 13. 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 on the first lens surface 11. Also, a second antireflection film 22 is formed on the inner peripheral side of the second holding portion 52 on the flange surface 13 and on the second lens surface 12. The first antireflection film 21 is laminated on the surface of the first lens surface 11 by vapor deposition or sputtering. The second antireflection film 22 is laminated on the surface of the second lens surface 12 and on the inner peripheral end portion exposed from the jig 50 on the surface of the flange surface 13 by vapor deposition or sputtering.

[0021] In the polishing step ST2, the entire surface of the flange surface 13 and the second antireflection film 22 are polished along the flange surface 13 with a predetermined polishing tool. Thereby, the antireflection film portion laminated on the flange surface 13 in the second antireflection film 22 is removed, and an annular end face 22a that is continuously connected to the flange surface 13 without a step is provided on the second antireflection film 22. The polished flange surface 13 and the annular end face 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 face 22a of the second antireflection film 22 is 10 μm.

[0022] In the ink coating step ST3, ink coating is performed on the entire surface of the flange surface 13. Also, in the ink coating step ST3, ink coating is performed on the annular end face 22a of the second antireflection film 22.

[0023] (Function and effect) FIG. 5 is an explanatory diagram of a conventional meniscus lens. In FIG. 5, the flange surface and the periphery of the second lens surface of the conventional meniscus lens are shown enlarged. FIG. 6 is a photograph of ghosting occurring in the conventional meniscus lens. FIG. 6 shows a state in which light rays are irradiated from a light source on the optical axis toward the first lens surface of the conventional meniscus lens, as viewed from the side of the second lens surface. FIG. 7 is a photograph of the meniscus lens 1 of this example in a state in which light rays are irradiated from a light source on the optical axis toward the first lens surface 11, as viewed from the side of the second lens surface 12.

[0024] Conventionally, in the method for forming an antireflection film and an ink coating film on the meniscus lens 100, there is no polishing step ST2 between the antireflection film forming step ST1 and the ink coating step ST3. That is, in the conventional method for forming an antireflection film and an ink coating film, the antireflection film forming step ST1 and the ink coating step ST3 are performed continuously. Therefore, in the conventional meniscus lens 100, at the start of the ink coating step 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. Thus, when the antireflection film forming step ST1 and the ink coating step ST3 are performed continuously, as shown in FIG. 5, the meniscus lens 100 has an overlapping portion 25 at the inner peripheral edge portion of the flange surface 13 where the second antireflection film 22 (antireflection film portion 22b) and the ink coating film 23 overlap in this order from the side of the flange surface 13.

[0025] When light rays are irradiated from a light source disposed on the optical axis L in front of the first lens surface of such a conventional meniscus lens 100 toward the first lens surface, as shown in FIG. 6, a ring-shaped ghost 101 is generated.

[0026] Regarding such a problem, as a result of intensive studies by the inventors, it was found that the ring-shaped ghost 101 generated when light rays are irradiated from a light source disposed on the optical axis L toward the first lens surface 11 is caused by the light rays 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 direction of the optical axis L and then traveling inside the meniscus lens 100 toward the side of the first lens surface 11.

[0027] Based on such findings, in the method for forming the antireflection film and the ink coating film in this example, an antireflection film forming step ST1, a polishing step ST2, and an ink coating step ST3 are provided in this order.

[0028] Here, in the antireflection film forming step ST1, the meniscus lens 1 is held by a jig 50 having an annular holding portion that covers a portion of the flange surface 13 that is separated from the second lens surface 12, and a second antireflection film 22 is formed on the inner peripheral side of the second lens surface 12 and the second holding portion 52 on the flange surface 13. Thereby, 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 antireflection film 22 can surely cover the second lens surface 12.

[0029] In the polishing step ST2 following the antireflection film forming step ST1, the flange surface 13 and the second antireflection film 22 are polished along the flange surface 13, and an antireflection film portion 22b of the second antireflection film 22 that is located on the side opposite to the first lens surface 11 with respect to the flange surface 13 in the optical axis L direction is removed, and an annular end face 22a that is continuous with the flange surface 13 without a step is provided on the second antireflection film 22. Then, in the ink coating step ST3, the entire surface of the flange surface 13 is inked. Thereby, 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, the black coating film 23 is laminated on the surface of the flange surface 13 and covers the entire surface of the flange surface 13. Therefore, in the meniscus lens 1, there is no overlapping portion 25 in which the second antireflection film 22 and the black coating film 23 are laminated in this order in the direction of the optical axis L on the surface of the flange surface 13. Thus, even when the meniscus lens 1 is irradiated with light rays from a light source arranged on the optical axis L toward the first lens surface 11, the light rays incident from the first lens surface 11 do not reflect at the inner peripheral edge portion of the flange surface 13. Therefore, as shown in FIG. 7, the generation of ring-shaped ghosts can be prevented or suppressed.

[0031] Also, in this example, in the black coating process ST3, black coating is performed on the annular end surface 22a of the second antireflection film 22. That is, in the meniscus lens 1 of this example, the second antireflection film 22 has an annular end surface 22a that is continuous with the flange surface 13 without a step, and the black coating film 23 covers the annular end surface 22a. According to such a configuration, the black coating film 23 has an overlapping portion 25 that overlaps with the annular end surface 22a of the second antireflection film 22 in the direction of the optical axis L 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 rays incident from the first lens surface 11 are reflected in the overlapping portion 25, it is not possible to generate ring-shaped ghosts. Here, if the black coating film 23 reaches up to the annular end surface 22a, it is possible to prevent the occurrence of remaining black coating at the inner peripheral end portion of the flange surface 13. Also, if the black coating film 23 covers the annular end surface 22a, it is possible to prevent or suppress the peeling of the second antireflection film 22 from the end portion on the side opposite to the first lens surface 11 of the second lens surface 12.

[0032] In the meniscus lens 1 of this example, the second antireflection film 22 has a multilayer structure, and 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 higher than the first refractive index, and the first refractive index layer are laminated in this order. Here, when the second antireflection film 22 has a multilayer structure, in the annular end face 22a that is continuous with the flange surface 13 without a step, each layer is likely to peel off. On the other hand, if the ink coating film 23 covers the annular end face 22a, these peelings 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 1 / 2 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] (Modification example) In the above example, in the polishing step ST2, the entire surface of the flange surface 13 is polished, but only the edge portion on the inner peripheral side of the flange surface 13 may be polished to remove the antireflection film portion laminated on the flange surface 13 in the second antireflection film 22.

[0035] FIG. 8 is an explanatory view of the meniscus lens 1A of Modification Example 1. FIG. 8 is a partially enlarged view of the periphery of the flange surface 13 and the second lens surface 12 of the meniscus lens 1A of Modification 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 covers only the flange surface 13. Even in this case, in the meniscus lens 1A, there is no overlapping portion 25 in which the second antireflection film 22 and the ink coating film 23 are laminated in this order in the direction of the optical axis L on the surface of the flange surface 13. Therefore, even when the meniscus lens 1A is irradiated with light rays from a light source arranged on the optical axis L toward the first lens surface 11, the light rays incident from the first lens surface 11 are reflected at the inner peripheral edge portion of the flange surface 13 and do not generate ghosts.

[0036] FIG. 9 is an explanatory view of the meniscus lens 1B of Modification 2. FIG. 9 is a partially enlarged view of the flange surface 13 and the peripheral portion of the second lens surface 12 of the meniscus lens 1B of Modification 2. In the meniscus lens 1B of this example, the black coating film 23 includes a covering portion 23a that covers, from the inner peripheral side, the end portion of the second antireflection film 22 that covers the end portion of the second lens surface 12 on the side opposite to the first lens surface 11 in the direction of the optical axis L. 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 toward the optical axis L from the flange surface 13 toward the side of the first lens surface 11. Therefore, even if there is a portion where the covering portion 23a of the second antireflection film 22 and the black coating film 23 overlaps at the end portion of the second lens surface 12 on the side opposite to the first lens surface 11, due to this structure, a ring-shaped ghost is not generated.

[0037] FIG. 10 is an explanatory view of the meniscus lens 1C of Modification 3. FIG. 10 is a partially enlarged view of the flange surface 13 and the peripheral portion 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 of the second lens surface 12 on the side opposite to the first lens surface 11 in the X-axis direction, there is provided a notch step portion 15 that is cut out from the side of the optical axis L (inner peripheral side) and the side in the X1 direction. In such a configuration, the second antireflection film 22 covers the surface of the notch step portion 15. Further, the second antireflection film 22 has an annular end face 22a that is continuously connected to the flange surface 13 without a step at the end in the X1 direction. The black 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 notch 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 applied to the flange surface 13 from dripping within the effective diameter of the second lens surface 12.

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

[0040] Here, the present technology can be configured as follows. (1) A meniscus lens having a convex first lens surface, a concave second lens surface that is recessed on the side of 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, and when viewed from the direction of the optical axis in the meniscus lens where the flange surface overlaps 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 continuous with the flange surface without a step, a black coating film is laminated on the surface of the flange surface, the black coating film is characterized in that it covers the entire surface of the flange surface.

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

[0042] (3) The antireflection film has a multilayer structure, and 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 laminated in this order on the surface of the second lens surface.

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

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

[0045] (6) The meniscus lens according to any one of (1) to (5), characterized in that the flange surface and the annular end surface are rough surfaces.

Explanation of reference numerals

[0046] 1, 1A, 1B, 1C... meniscus lenses, 11... first lens surface, 12... second lens surface, 13... flange surface, 14... annular surface, 15... notch step portion, 21... first antireflection film, 22... second antireflection film, 22a... annular end surface, 23... black coating film, 23... second antireflection film, 50... jig, 51... first holding portion, 52... second holding portion, 100... conventional meniscus lens

Claims

1. A meniscus lens having a convex first lens surface, a concave second lens surface that is recessed on the side of 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, wherein when viewed in the optical axis direction, the flange surface overlaps 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 continuous with the flange surface without a step, an ink coating film is laminated on the surface of the flange surface, the meniscus lens, wherein the ink coating film covers the entire surface of the flange surface.

2. The meniscus lens according to claim 1, wherein the ink coating film covers the annular end face.

3. The antireflection film has a multilayer structure, and 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 laminated in this order on the surface of the second lens surface. The meniscus lens according to claim 2, characterized by this.

4. The meniscus lens according to claim 2 or 3, wherein the ink coating film includes a covering portion that covers, from the inner peripheral side, an end portion of the antireflection film on the side opposite to the first lens of the second lens surface in the optical axis direction.

5. The meniscus lens according to any one of claims 1 to 3, wherein a notch step portion that is cut out from the optical axis side and the side opposite to the first lens surface is provided at an end of the second lens surface on the side opposite to the first lens surface in the optical axis direction.

6. The meniscus lens according to any one of claims 1 to 3, wherein the flange surface and the annular end face are rough surfaces.

7. In a method for forming an antireflection film and an ink coating film on a meniscus lens having a convex first lens surface, a concave second lens surface that is recessed on the side of 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, and when viewed in the optical axis direction, the flange surface overlaps the first lens surface, The meniscus lens is held by a jig including an annular holding portion that covers a portion spaced apart from the second lens surface on the flange surface, and an antireflection film forming step of forming an antireflection film on the inner peripheral side of the holding portion on the flange surface and on the second lens surface; a polishing step of polishing the flange surface and the antireflection film along the flange surface to remove the antireflection film portion laminated on the flange surface and to provide an annular end surface that is continuous with the flange surface without a step on the antireflection film; an ink coating step of applying ink to the entire surface of the flange surface; A method for forming an antireflection film and an ink coating film, characterized by comprising the above steps.

8. The method for forming an antireflection film and an ink coating film on a meniscus lens according to claim 7, wherein in the ink coating step, ink is applied to the annular end surface of the antireflection film.

Images