Optical component, method for manufacturing an optical component, optical instrument, and imaging device

Abstract

To provide an optical member that has low reflectance even if an incident angle is increased.SOLUTION: An optical member 10 has: a substrate 1 that has a first surface 11; a porous layer 2 that is provided on the first surface 11 of the substrate and has a plurality of holes 23; a first convex part row 3 that is formed of a plurality of first concave parts provided on a surface 22 of the porous layer at an interval in a first direction; and a second convex part row 4 that is formed of a plurality of second concave parts provided at an interval in parallel with the first concave parts. The interval d between the first concave part row 3 and the second concave part row 4 in a second direction intersecting the first direction is larger than the height h1 of the first concave part row and the height h2 of the second concave part row.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical member, a method for manufacturing an optical member, an optical device, and an imaging device.

Background Art

[0002] An optical device such as an interchangeable lens includes a housing and an optical system having at least one lens provided in the housing. Light rays incident on the optical device mainly enter the lens and form a subject image by being imaged. On the other hand, there are also light rays that are not imaged and do not contribute to the formation of the subject image. Since the light rays that do not contribute to the formation of the subject image are incident from disordered directions, they also enter parts other than the lens and become factors causing unnecessary reflections and scattering in the housing. These lights are called stray light. When the stray light reaches the imaging element, it becomes a factor causing flare and ghost.

[0003] As a means for suppressing stray light, Patent Document 1 discloses an article having an electroless nickel black plating film excellent in wear resistance that can be used for cameras and the like.

Prior Art Documents

Patent Documents

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] [[ID=已39]]However, the article disclosed in Patent Document 1 has a problem that the reflectance increases when the incident angle of light rays becomes large.

Means for Solving the Problems

[0006] A first aspect for solving the above problems is a base material having a first surface, a porous layer provided on the first surface of the base material and having a plurality of holes, The surface of the porous layer is provided with a row of first protrusions, each of which is spaced apart in a first direction, The porous layer has a row of second protrusions, each consisting of multiple second protrusions spaced apart and parallel to the first protrusions, The interval between the first row of protrusions and the second row of protrusions, which is the average value of the interval between the first protrusion and the adjacent second protrusion in a second direction orthogonal to the first direction, is greater than the average value of the height of the first row of protrusions and the average value of the height of the second row of protrusions. The length of the first row of protrusions in the second direction and the length of the second row of protrusions in the second direction are such that the porous layer Length in the second direction This optical component is characterized by being larger in size.

[0007] A second aspect for solving the above problem is a preparation step of preparing a member having a substrate having a first surface and a porous layer having a plurality of holes on the first surface of the substrate, A processing step of providing the surface of the porous layer with a first row of protrusions consisting of a plurality of first protrusions, each spaced apart in a first direction, and a second row of protrusions consisting of a plurality of second protrusions, each spaced apart parallel to the first protrusions. It has, In the aforementioned processing step, the distance between the row of first protrusions and the row of second protrusions, which is the average value of the distance between the first protrusion and the adjacent second protrusion in a second direction perpendicular to the first direction, is set to be greater than the average value of the height of the row of first protrusions and the average value of the height of the row of second protrusions. The length of the first row of protrusions in the second direction and the length of the second row of protrusions in the second direction are such that the porous layer Length in the second direction This is a method for manufacturing optical components, characterized by having a larger configuration. [Effects of the Invention]

[0008] According to the above solution, it is possible to provide an optical element with low reflectivity even at large angles of incidence, and a method for manufacturing the same. Furthermore, it is possible to provide optical equipment and imaging devices using the optical element. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram of an optical element according to the first embodiment. [Figure 2] This is a schematic diagram of a modified optical component. [Figure 3] This is a schematic diagram showing a method for manufacturing an optical component according to the first embodiment. [Figure 4] This is a schematic diagram of the imaging device according to the second embodiment. [Figure 5] This is a cross-sectional SEM image of the optical component of Example 1. [Figure 6] This figure shows the reflectance of the optical element of Example 1 and the optical element of Comparative Example 1. [Figure 7] This is a schematic diagram of an optical component in a comparative example. [Modes for carrying out the invention]

[0010] [First Embodiment] (Optical components) Figure 1 is a schematic diagram of an optical member according to the first embodiment, where Figure 1(a) is a side view and Figure 1(b) is a top view. The optical member 10 according to the first embodiment includes a base material 1, a porous layer 2, a first row of protrusions 3, and a second row of protrusions 4.

[0011] In Figure 1, the direction in which the porous layer 2 is laminated on the substrate 1 is defined as the Z-axis. The direction in which the first row of protrusions 3 and the second row of protrusions 4 are adjacent is defined as the X-axis. The direction perpendicular to the Z-axis and X-axis is defined as the Y-axis. In this XYZ coordinate system, the direction along the X-axis is called the X-axis direction, the direction along the Y-axis is called the Y-axis direction, and the direction along the Z-axis is called the Z-axis direction.

[0012] The base material 1 has a first surface 11 and a second surface 12 which is on the opposite side of the first surface. A porous layer 2 described later is provided on the first surface 11. Nothing may be provided on the second surface 12, but for example, an adhesive 31 can be provided. The optical member of the first embodiment can be easily attached to another structure like a seal by providing the adhesive 31 on the second surface 12. The adhesive 31 may be provided in a form integrated with a release paper like a double-sided tape.

[0013] The thickness of the base material 1 is not particularly limited, but from the viewpoint of maintaining the mechanical strength of the optical member, it is preferably 100 μm or more.

[0014] The material of the base material 1 is not particularly limited, and for example, a resin can be used. The resin is preferably in the form of a film (sheet), and for example, a material with sufficient mechanical strength such as polycarbonate, polystyrene, acrylonitrile - butadiene - styrene (ABS), etc. is preferably used. Also, from the viewpoint of being easy to attach to other structures, it is also preferable to use a resin with flexibility, and for example, polyurethane can be used.

[0015] The porous layer 2 is provided on the first surface 11 of the base material 1 and has a plurality of holes 23. The porous layer 2 has a first surface 22 in contact with the first surface 11 of the base material 1 and a second surface 21 which is on the opposite side of the first surface 22 not in contact with the first surface 11 of the base material. The second surface 21 is the exposed surface. A first convex portion row 3 and a second convex portion row 4 are provided on the second surface 21 which is the surface of the porous layer. The porous layer 2 is a member that absorbs light rays entering from the second surface 21 side.

[0016] The porous layer 2 is preferably dyed with a black dye. By dyeing the porous layer 2 black, the light absorption efficiency can be increased. The type of black dye is not particularly limited and may be an organic material such as dyeing ink, or an inorganic material containing metals such as nickel, cobalt, or copper. Here, black refers to a color that absorbs light across the entire range of wavelengths from 380 nm to 780 nm. Furthermore, the porous layer 2 is preferably blackness of 0.7 or higher, which is expressed as the ratio of the maximum absorptivity to the minimum absorptivity in the range of wavelengths from 380 nm to 780 nm.

[0017] In Figure 1(a), the multiple holes 23 are uniformly extended in the Z direction, but the shape of the holes 23 is not limited to this shape. They do not have to penetrate in the Z direction, and they may be circles, ellipses, or polygons when viewed from above or from the side. The holes 23 may also be in communication with the first row of protrusions 3 and the second row of protrusions 4, which will be described later, from the porous layer 2.

[0018] The material of the porous layer 2 is not particularly limited, but from the viewpoint of simplifying the manufacturing process, it is preferable to form it from the same material as the base material 1. A detailed method for forming the porous layer 2 will be described in the manufacturing method section.

[0019] The first row of protrusions 3 is provided on the second surface 21 of the porous layer 2. The first row of protrusions 3 has a plurality of first protrusions 3a, 3b, 3c. The first protrusions 3a, 3b, 3c are provided at predetermined intervals in the Y direction in Figure 1(b). That is, the first row of protrusions 3 is provided on a straight line when viewed from above in the Z direction. The average length of the first protrusions 3a, 3b, 3c in the X direction is denoted as the X direction length w1 of the first row of protrusions 3. The average length of the first protrusions 3a, 3b, 3c in the Y direction is denoted as the Y direction length t1 of the first row of protrusions 3. The average length of the first protrusions 3a, 3b, 3c in the Z direction is denoted as the Z direction length (height) h1 of the first row of protrusions 3. The average angle between the first protrusions 3a, 3b, 3c and the second surface 21 of the porous layer is denoted as θ1. The average values ​​of w1, t1, h1, and θ1 mentioned above can be calculated from values ​​measured at three or more locations in SEM images, etc.

[0020] In Figure 1(b), there are three first protrusions, but the number is not limited to three; any number is acceptable. Preferably, the shape of the first protrusions 3a, 3b, and 3c is triangular when viewed from the side in the Y direction, with their tips tapering toward the Z direction. The tapering, sharp convex shape of the first protrusions 3a, 3b, and 3c improves the efficiency of phenomena such as reflection, diffusion, and scattering that occur between the first protrusions themselves or between the first and second protrusions. As a result, the amount of light rays returning to the optical path can be further reduced. However, the shape of the first protrusions 3a, 3b, and 3c may also be a plano-convex shape, such as a rectangle or trapezoid when viewed from the side. The material of the row of first protrusions 3 is not particularly limited, but from the viewpoint of simplifying the manufacturing process, it is preferable that it be formed from the same material as the porous layer 2. A detailed method for forming the row of first protrusions 3 will be described in the manufacturing method section.

[0021] The second row of protrusions 4 is provided on the second surface 21 of the porous layer 2. The second row of protrusions 4 is provided parallel to the first row of protrusions 3 with a spacing d in the X direction. The second row of protrusions 4 has a plurality of first protrusions 4a, 4b, 4c. The second protrusions 4a, 4b, 4c are provided at predetermined intervals in the Y direction in Figure 1(b). That is, the second row of protrusions 4 is provided in a straight line when viewed from above in the Z direction. The average length of the second protrusions 4a, 4b, 4c in the X direction is denoted as the length w2 of the second row of protrusions 4 in the X direction. The average length of the second protrusions 4a, 4b, 4c in the Y direction is denoted as the length t2 of the second row of protrusions 4 in the Y direction. The average length of the second protrusions 4a, 4b, 4c in the Z direction is denoted as the length (height) h2 of the second row of protrusions 4 in the Z direction. Let θ2 be the average value of the angles that the second protrusions 4a, 4b, and 4c make with the second surface 22 of the porous layer. Note that the average values ​​of w2, t2, h2, and θ2 mentioned above can be calculated from values ​​measured at three or more locations using SEM images, etc.

[0022] The second protrusions 4a, 4b, and 4c are provided at predetermined intervals in the Y direction in Figure 1(b). In Figure 1(b), there are three second protrusions, but the number is not limited to three; there can be multiple. Preferably, the shape of the second protrusions 4a, 4b, and 4c is triangular when viewed from the side, with their tips tapering toward the Z direction. The tapering, sharp convex shape of the tips of the second protrusions 4a, 4b, and 4c improves the efficiency of phenomena such as reflection, diffusion, and scattering that occur between the second protrusions or between the first and second protrusions. As a result, the amount of light rays returning to the optical path can be further reduced. However, the shape of the second protrusions 4a, 4b, and 4c may also be a plano-convex shape, such as a rectangle or trapezoid when viewed from the side. The material of the row of second protrusions 4 is not particularly limited, but from the viewpoint of simplifying the manufacturing process, it is preferable that it be formed from the same material as the porous layer 2. A detailed method for forming the row of second protrusions 4 will be described in the manufacturing method section.

[0023] Here, the comparative optical member 10X will be described. Figure 7 is a schematic diagram of the comparative optical member, with Figure 7(a) being a side view and Figure 7(b) being a top view. The comparative optical member 10X is the same as the optical member 10 of the first embodiment in that it has a base material 1X, a porous layer 2X, a first row of protrusions 3X, and a second row of protrusions 4X. The comparative optical member 10X differs from the optical member 10 of the first embodiment in that the distance between the first row of protrusions 3X and the second row of protrusions 4X is dX.

[0024] In the comparative example optical member 10X, the distance dX between the first row of protrusions 3X and the second row of protrusions 4X is less than or equal to the height of the first row of protrusions 3X and the height of the second row of protrusions 4X. More specifically, the distance dX between the first row of protrusions 3X and the second row of protrusions 4X is less than or equal to the average height h1x of the first row of protrusions 3X and the average height h2x of the second row of protrusions 4X. The average height h1x of the first row of protrusions 3X is calculated from the average value of the heights of each of the first row of protrusions 3aX, 3bX, and 3cX. The average height h2x of the second row of protrusions 4X is calculated from the average value of the heights of each of the second row of protrusions 4aX, 4bX, and 4cX.

[0025] The inventors of this application conducted thorough research and found that when the distance dX between the first row of protrusions 3X and the second row of protrusions 4X is less than or equal to the heights of the first row of protrusions 3X and the second row of protrusions 4X, the reflectivity cannot be reduced as the angle of incidence of the light ray increases. Specifically, the comparative optical member 10X can absorb many light rays when the angle of incidence of the light ray is perpendicular or nearly perpendicular to the first surface 11X of the substrate 1X, but it was found that when the angle of incidence of the light ray exceeds 80 degrees, it is reflected at the tips of the rows of protrusions. As a result, it was found that it is difficult to reduce the amount of light rays that return to the optical path.

[0026] Therefore, the optical member 10 of the first embodiment is configured such that the distance d between the first row of protrusions 3 and the second row of protrusions 4 is greater than the height of the first row of protrusions 3 and the height of the second row of protrusions 4. More specifically, the distance d between the first row of protrusions 3 and the second row of protrusions 4 is greater than the height h1 of the first row of protrusions 3 and the height h2 of the second row of protrusions 4. By adopting such a configuration, the optical member 10 can reduce reflection at the tips of the rows of protrusions compared to the comparative example, and can absorb more light rays even when the incident angle exceeds 80 degrees. As a result, the amount of light rays returning to the optical path can be reduced.

[0027] The spacing d between the first row of protrusions 3 and the second row of protrusions 4 is preferably three times or more the height of the first row of protrusions and the height of the second row of protrusions. This further reduces reflection at the tips of the rows of protrusions, allowing more light rays to be absorbed even when the incident angle exceeds 80 degrees. As a result, the amount of light rays returning to the optical path can be further reduced. More preferably, this spacing is four times or more.

[0028] It is preferable that the length w1 in the X direction of the first row of protrusions 3 and the length w2 in the X direction of the second row of protrusions 4 are greater than the pore diameter φ of the porous layer. By adopting such a configuration, the mechanical strength of the first protrusions 3a, 3b, 3c and the second protrusions 4a, 4b, 4c can be increased. The pore diameter φ of the porous layer 2 is the length of the porous layer 2 in the X direction and can be measured from a cross-sectional SEM image, etc. The pore diameter to be used for comparison is, for example, the pore 23 located directly below (below in the Z direction) the first row of protrusions 3 or the second row of protrusions 4.

[0029] The length w1 in the X direction of the first row of protrusions 3 and the length w2 in the X direction of the second row of protrusions 4 are preferably 200 μm or more. By adopting such a configuration, the mechanical strength of the first protrusions 3a, 3b, 3c and the second protrusions 4a, 4b, 4c is increased and a large amount of light can be absorbed.

[0030] It is preferable that the angle between the first row of protrusions 3 and the second protrusion 4 and the second surface 22 of the porous layer 2 is 135 degrees or less. This is because even at a high angle of incidence, a large amount of light rays can be absorbed, and the amount of light rays returning to the optical path can be reduced. (modified version) Furthermore, in the embodiment described above, the first row of protrusions 3 and the second row of protrusions 4 were arranged on straight lines when viewed from above, but they may also be arranged on curves as shown in Figure 2(a). If the light rays containing unwanted light are synchrotron radiation, by arranging them on a curve of arbitrary curvature that reflects the radiation angle of the synchrotron radiation, it is possible to absorb many light rays and reduce the amount of light rays returning to the optical path.

[0031] Furthermore, the optical member of this disclosure may have a third row of protrusions 5 provided on the second surface 21 of the porous layer 2, as shown in Figure 2(b). The third row of protrusions 3 has a plurality of third protrusions 5a, 5b, 5c. The third protrusions 5a, 5b, 5c are provided at predetermined intervals in the X direction in Figure 2(b). That is, the third row of protrusions 5 is provided in a straight line when viewed from above in the Z direction. The average length of the third protrusions 5a, 5b, 5c in the Y direction is defined as the Y direction length w3 of the third row of protrusions 5. The average length of the third protrusions 5a, 5b, 5c in the Y direction is defined as the X direction length t3 of the third row of protrusions 5. The average length of the third protrusions 5a, 5b, 5c in the Z direction is defined as the Z direction length (height) h3 of the third row of protrusions 5.

[0032] Furthermore, the optical member of this disclosure may have a fourth row of protrusions 6 provided on the second surface 21 of the porous layer 2, as shown in Figure 2(b). The fourth row of protrusions 6 is provided parallel to the third row of protrusions 5 at predetermined intervals in the Y direction. The fourth row of protrusions 6 has a plurality of fourth protrusions 6a, 6b, 6c. The fourth protrusions 6a, 6b, 6c are provided at predetermined intervals in the X direction in Figure 2(b). That is, the fourth row of protrusions 6 is provided in a straight line when viewed from above in the Z direction. The average value of the lengths of the fourth protrusions 6a, 6b, 6c in the Y direction is the length w3 of the third row of protrusions 5 in the X direction. The average value of the lengths of the third protrusions 5a, 5b, 5c in the Y direction is the length t3 of the third row of protrusions 5 in the X direction. The average value of the lengths of the third protrusions 5a, 5b, 5c in the Z direction is the length (height) h3 of the third row of protrusions 5 in the Z direction.

[0033] When viewed from above in the Z direction, the third protrusion 5a intersects with the first protrusion 5a, the third protrusion 5b intersects with the second protrusion 4a, the fourth protrusion 6a intersects with the first protrusion 3b, and the fourth protrusion 6b intersects with the second protrusion 4b. In other words, when viewed from above in the Z direction, at least a portion of the first row of protrusions 3 intersects with the third protrusion 5 and the fourth protrusion 6. Also, when viewed from above in the Z direction, at least a portion of the second row of protrusions 4 intersects with the third protrusion 5 and the fourth protrusion 6.

[0034] The distance between the third row of protrusions 5 and the fourth row of protrusions 6 is preferably greater than the height of the third row of protrusions 5 and the height of the fourth row of protrusions 6. More specifically, the distance between the third row of protrusions 5 and the fourth row of protrusions 6 is preferably greater than the height of the third row of protrusions 3 and the height of the fourth row of protrusions 6. By adopting such a configuration, the amount of light rays incident from the Y direction that return to the optical path can be reduced.

[0035] Furthermore, the optical member of this disclosure may have a fifth row of protrusions 7 provided on the second surface 22 of the porous layer 2, as shown in Figure 2(c). The fifth row of protrusions 7 has a plurality of fifth protrusions 7a, 7b. The fifth protrusions 7a, 7b are provided at predetermined intervals in the Y direction in Figure 2(c). However, the fifth protrusions 7a, 7b do not face the first protrusions 3a, 3b, 3c and the second protrusions 4a, 4b, 4c in the X direction.

[0036] In the embodiment described above, the second row of protrusions 4 was provided extending in the Y direction parallel to the first row of protrusions 3, but a deviation of ±10 degrees or less can reduce the amount of light rays returning to the optical path. Similarly, the fourth row of protrusions 6 was provided extending in the X direction parallel to the third row of protrusions 5, but a deviation of ±10 degrees or less can reduce the amount of light rays returning to the optical path.

[0037] It should be noted that the lengths and angles in each direction of the first protrusions 3a, 3b, and 3c, and the lengths and angles in each direction of the second protrusions 4a, 4b, and 4c, as described above, do not need to be satisfied at all points in the optical member 10. If they are satisfied at least in part of the optical member 10, the amount of light rays returning to the optical path in that part can be reduced.

[0038] In the embodiments described above, the substrate material was resin, but it may also be metal, graphene, or carbon nanotubes.

[0039] (Manufacturing method for optical components) Figure 3 is a schematic diagram showing a method for manufacturing an optical component according to the first embodiment.

[0040] First, as shown in Figures 3(a) and 3(b), a preparation step S1 is performed to prepare a base material 1 having a first surface 11 and a member having a porous layer 2 with a plurality of holes 23 on the first surface 11 of the base material 1. The preparation step S1 can be broadly divided into a base material preparation step S11, which prepares the base material 1 having a first surface 11, and a lamination step S12, which provides the porous layer 2 with a plurality of holes 23 on the first surface 11 of the base material 1.

[0041] As a substrate preparation step S11, first, a substrate 1 is prepared. For example, the substrate 1 is a sheet-shaped resin film. If necessary, it is preferable to remove any dirt or oil adhering to the first surface 11 of the substrate 1.

[0042] Next, in lamination step S12, the raw materials for the porous layer 2 are prepared. These raw materials are the precursor 2A of the porous layer and include, for example, a solvent, a resin, a black dyeing agent, and a film-forming aid. The types of solvent and film-forming aid are not particularly limited and can be appropriately determined depending on the type of resin. A wet film-forming aid is preferred as the film-forming aid. A commercially available example is the CUT series manufactured by Dainichi Seika Kogyo Co., Ltd. The precursor 2A of the porous layer is placed on the first surface 11 of the substrate 1 as shown in Figure 3(a). The method of placing the precursor 2A on the first surface 11 is not particularly limited and can be done, for example, using a squeegee or a dispenser. The thickness of the precursor 2A is not particularly limited, but it is preferable to make it thick enough so that the heights of the first row of protrusions 3 and the second row of protrusions 4 can be obtained in the subsequent steps.

[0043] Next, multiple pores 23 are created in the precursor 2A. The method for creating the multiple pores 23 is not particularly limited, but for example, pores can be created by immersing the precursor 2A in water, replacing the solvent in the precursor 2A with water, and generating bubbles. At this time, as shown in Figure 3(b), a surface layer 24 made of a resin without pores is formed on the porous layer 2.

[0044] Next, a processing step S2 is performed on the second surface 22 of the porous layer 2, in which a first row of protrusions 3, each consisting of multiple first protrusions spaced apart in the Y direction, and a second row of protrusions 4, each consisting of multiple second protrusions spaced apart parallel to the first protrusions, are provided. As shown in Figures 3(b) and 3(c), in processing step S2, the spacing between the first row of protrusions 3 and the second row of protrusions 4 in the X direction is set to be greater than the height of the first row of protrusions 3 and the height of the second row of protrusions 4.

[0045] The means for performing the processing step S2 are not particularly limited, but it is preferable to use a laser from the viewpoint of enabling a short processing time and minimizing damage to the finished optical component. The laser is, for example, an excimer laser. Processing step S2 involves preparing a laser 40 as shown in Figure 3(b). Then, a mask (not shown) is placed between the beam of the laser 40 and the surface layer 24. The mask is preferably a trapezoidal aperture mask. Subsequently, as shown in Figure 3(c), the substrate 1 is moved in the X direction relative to the laser 40 using a stage or the like to form the first row of protrusions 3 and the second row of protrusions 4.

[0046] The spacing between the first row of protrusions 3 and the second row of protrusions 4, the width of the rows of protrusions, and the angle of the protrusions can be controlled by the shape of the mask. In particular, in the case of a trapezoidal aperture mask, it is possible to control these parameters by the size of the hypotenuse of the trapezoid. Furthermore, the heights of the first row of protrusions 3 and the second row of protrusions 4 can be adjusted by the scanning speed of the laser 40, the processing time, and the energy density of the laser.

[0047] By performing the above steps, the optical member 10 of the first embodiment shown in Figure 3(d) can be obtained.

[0048] In the embodiments described above, the substrate material was resin, but it may also be metal, graphene, or carbon nanotubes.

[0049] Furthermore, the method for forming the porous layer is not particularly limited. For example, when the substrate material is aluminum or an aluminum alloy, the porous layer can be formed by anodizing. When the substrate material is graphene, the porous layer can be formed by orienting the graphene using known methods such as plasma CVD. In addition, when using resin as in the embodiments described above, it may be manufactured using a mold.

[0050] [Second Embodiment] (Optical instruments, imaging devices) Figure 4 shows the configuration of a single-lens reflex digital camera, which is an example of a preferred embodiment of the imaging device of the present invention. In Figure 4, the camera body 602 and the lens barrel 601, which is an optical device, are coupled together, and the lens barrel 601 is a so-called interchangeable lens that can be attached to and detached from the camera body 602.

[0051] Light from the subject passes through an optical system consisting of multiple lenses 603, 605, etc., arranged on the optical axis of the imaging optical system within the housing 620 of the lens barrel 601, and is received by the image sensor 610. Here, lens 605 is supported by an inner barrel 604 and is movably supported relative to the outer barrel of the lens barrel 601 for focusing and zooming. The inner barrel 604 is a support for lens 605.

[0052] During the observation period before shooting, light from the subject is reflected by the main mirror 607 inside the camera body housing 621, passes through the prism 611, and the image is projected onto the photographer through the viewfinder lens 612. The main mirror 607 is, for example, a half-mirror, and the light that passes through the main mirror is reflected by the sub-mirror 608 towards the AF (autofocus) unit 613, and this reflected light is used, for example, for distance measurement. The main mirror 607 is also attached and supported by the main mirror holder 640 by adhesive or other means. During shooting, the main mirror 607 and sub-mirror 608 are moved out of the optical path via a drive mechanism (not shown), the shutter 609 is opened, and the image of the photographic light incident from the lens barrel 601 is projected onto the image sensor 610. The aperture 606 is configured to change the brightness and depth of field during shooting by changing the aperture area.

[0053] The optical member of the first embodiment can be suitably used in imaging devices and optical instruments by forming a first row of protrusions 3 and a second row of protrusions 4 on the inner wall side of a housing 620 and an inner cylinder 604 as base materials. Alternatively, if the first row of protrusions 3 and the second row of protrusions 4 are positioned on the inner wall side, the housing 620 and inner cylinder 604 may be formed from a metal such as magnesium, and the optical member 10 may be provided with an adhesive 31 and attached to the housing 620 and inner cylinder 604 via the adhesive 31.

[0054] Furthermore, in Figure 4, the dashed line represents the optical axis of the imaging optical system. By arranging the optical member 10 so that the first row of protrusions 3 and the second row of protrusions 4 intersect the optical axis, the probability of flare and ghosting can be further reduced. Moreover, it is even more preferable to arrange the optical member so that the first row of protrusions 3 and the second row of protrusions 4 are perpendicular to the optical axis (the direction in which light rays containing unwanted light are incident).

[0055] The optical device of the second embodiment has a portion within the housing that has low reflectivity even at large incident angles. Therefore, images captured using an imaging device having the optical device and image sensor of the second embodiment can have a sufficiently low probability of flare and ghosting occurring. [Examples]

[0056] (Example 1) The optical component 10 of the first embodiment shown in Figure 1 was manufactured using the manufacturing method shown in Figure 3. The method is described below.

[0057] First, a 200 μm thick polycarbonate film was prepared as the base material 1.

[0058] Next, the raw materials for the porous layer were prepared. Specifically, a mixture of N,N-dimethylformamide, a wet film-forming aid, and a carbon black dispersion was added to a polyurethane resin solution and stirred to obtain a mixed solution. Here, the carbon black dispersion was prepared by dispersing 12% by mass of carbon black in 2-methoxy-1-methylethyl acetate as a solvent. The weight ratio of this mixed solution was 30 parts N,N-dimethylformamide, 4 parts wet film-forming aid, and 5 parts carbon black dispersion, with the polyurethane resin solution being 100 parts.

[0059] Next, as shown in Figure 3(a), a porous layer was created on the polycarbonate film. Specifically, the obtained mixed solution was first applied to the first surface, which is the main surface of the polycarbonate film, using a squeegee. That is, the precursor 2A of the porous layer was placed on the first surface 11 of the substrate 1.

[0060] Next, the film coated with the mixed solution was placed in a tank containing water heated to 30°C and immersed in the water for 15 minutes. N,N-dimethylformamide was replaced by water, a large amount of bubbles were generated in the tank, and a porous layer 2 with multiple pores 23 was formed. At this stage, N,N-dimethylformamide remained in the pores, so to remove this N,N-dimethylformamide, the film was immersed in water heated to 60°C for 60 minutes. Furthermore, since water also remained in the pores, to remove this water, the film was dried in an oven heated to 100°C for 1 hour. The sum of the thickness of the porous layer 2 and the thickness of the surface layer 24 after drying was 400 μm.

[0061] Next, as shown in Figures 3(b) and 3(c), the first and second rows of protrusions were formed using an excimer laser (oscillation wavelength: 193 nm) to obtain the optical component of Example 1. The laser beam of the excimer laser had a repetition frequency of 200 Hz and an energy density of 560 mJ / cm². 2 The light was pulsed. The scanning speed was set to 0.2 mm / second.

[0062] Figure 5 shows an example of a cross-sectional SEM image of the optical element of Example 1. The dimensions of each part of the optical element 10 were evaluated from multiple cross-sectional SEM images. As a result, the length of the first row of protrusions in the X direction was 120 μm, and the length of the second row of protrusions in the X direction was 150 μm. The height of the first row of protrusions was 125 μm, and the height of the second row of protrusions was 120 μm. The distance between the first row of protrusions and the second row of protrusions in the X direction was 1250 μm.

[0063] (Comparative Example 1) Comparative Example 1 differs in the shape of the mask used during processing with the excimer laser. Aside from this difference, the optical component of Comparative Example 1 was fabricated under the same conditions as in Example 1.

[0064] In Comparative Example 1, the optical element had a first row of protrusions with a length of 30 μm in the X direction, and a second row of protrusions with a length of 30 μm in the X direction. The height of the first row of protrusions was 250 μm, and the height of the second row of protrusions was 250 μm. The distance between the first row of protrusions and the second row of protrusions in the X direction was 100 μm.

[0065] (Examples 2 and 3) Examples 2 and 3 differ in the shape of the mask used during processing with the excimer laser. Aside from this, the optical components of Examples 2 and 3 were fabricated under the same conditions as Example 1.

[0066] In Example 2, the optical element had a first row of protrusions with a length of 140 μm in the X direction, and a second row of protrusions with a length of 140 μm in the X direction. The height of the first row of protrusions was 130 μm, and the height of the second row of protrusions was 130 μm. The distance between the first row of protrusions and the second row of protrusions in the X direction was 500 μm.

[0067] In Example 3, the optical element had a first row of protrusions with a length of 120 μm in the X direction, and a second row of protrusions with a length of 120 μm in the X direction. The height of the first row of protrusions was 120 μm, and the height of the second row of protrusions was 130 μm. The distance between the first row of protrusions and the second row of protrusions in the X direction was 2000 μm.

[0068] (Examples 4 and 5) Examples 4 and 5 differ from Example 1 in the excimer laser scanning speed. Aside from this difference, the optical components for Examples 4 and 5 were fabricated under the same conditions as Example 1.

[0069] In Example 4, the scanning speed was set to 0.15 mm / second. In Example 4, the optical element had a first row of protrusions with a length in the X direction of 120 μm and a second row of protrusions with a length in the X direction of 150 μm. The height of the first row of protrusions was 195 μm, and the height of the second row of protrusions was 200 μm. The distance between the first and second rows of protrusions in the X direction was 1250 μm. The reason why the height of the protrusion rows is higher than in Example 1 is that the irradiation energy of the laser at the predetermined position is higher, and the amount of material removed by laser ablation is increased.

[0070] In Example 5, the scanning speed was set to 0.30 mm / second. In Example 4, the optical element had a first row of protrusions with a length in the X direction of 120 μm and a second row of protrusions with a length in the X direction of 150 μm. The height of the first row of protrusions was 100 μm, and the height of the second row of protrusions was also 100 μm. The distance between the first and second rows of protrusions in the X direction was 1250 μm. The reason why the height of the protrusion rows is lower than in Example 1 is that the irradiation energy of the laser at the predetermined position is lower, and the amount of material removed by laser ablation is reduced.

[0071] [Optical properties evaluation] The reflectance of the optical component was measured at 1 nm intervals between wavelengths of 500 nm and 600 nm using an ultraviolet-visible-near-infrared spectrophotometer (manufactured by JASCO Corporation, product name: V-770), with the incident angle of the light ray set to a desired value. The average value of these measurements was taken as the reflectance at the given incident angle. The measurements were performed after background correction.

[0072] Figure 6 is a graph comparing the reflectance of Example 1 and Comparative Example 1. The horizontal axis represents the angle of incidence of the light ray, and the vertical axis represents the reflectance on a logarithmic scale. Example 1, shown by the solid line, has a lower reflectance than Comparative Example 1, shown by the dashed line.

[0073] The reflectivity of the optical components of Examples 1-3 and Comparative Example 1 was compared. The reflectivity of Examples 2 and 3 at an incident angle of 85° was 0.15%, which is slightly lower than Example 1's 0.10% but lower than Comparative Example 1's 0.25%.

[0074] The reflectance of the optical components of Examples 1, 4, and 5 and Comparative Example 1 was compared. The reflectance of Example 4 at an incident angle of 85° was 0.07%, and the reflectance of Example 5 at an incident angle of 85° was 0.14%, both lower than the 0.25% of Comparative Example 1. Thus, it was confirmed that the effect of reducing reflectance is greater as the scanning speed decreases. This is thought to be due to the increased height of the convex rows, which increased the effect of blocking reflected and scattered light from the parts of the porous layer surface without convex rows, and the increased complexity of the surface shape due to ablation.

[0075] [Mechanical strength evaluation] The mechanical strength of the optical components of Examples 1 to 5 was evaluated by touching them with a finger. 2 The test involved rubbing the surface 10 times to apply a force equivalent to the specified amount, followed by blowing air through it with an air gun. This process was repeated up to three times. The reflectance before and after the test was compared, but there was only a maximum change of about 0.02%, and no significant change in performance was observed.

[0076] Based on the above, Examples 1 to 5, in which the spacing between the first and second rows of protrusions in the X direction was greater than the average height of the first and second rows of protrusions, all showed good values ​​of 0.2% or less average reflectance at an incident angle of 85 degrees in the wavelength range of 500 nm to 600 nm. Furthermore, since this disclosure does not involve processes such as creating uneven shapes with fillers or joining protrusions like electrostatic flocking, there is no risk of the rows of protrusions falling off or peeling off due to aging or vibration. Therefore, it is possible to provide an optical component in which the optical properties are less likely to fluctuate. [Explanation of symbols]

[0077] 1 Base material 2. Porous layer 2A Precursor of porous layer 3. First convex column 3a First protrusion 3b 1st convex part 3c First protrusion 4. Second convex column 4a Second protrusion 4b Second protrusion 4c Second protrusion 5. Third convex row 5a Third protrusion 5b Third protrusion 5c Third protrusion 6. Fourth convex column 6a Fourth protrusion 6b Fourth protrusion 6c Fourth protrusion 7. Fifth convex row 7a Fifth protrusion 7b Fifth protrusion 7c 5th convex part 10 Optical components 11 (First surface of the substrate) 12 (Second surface of the base material) 21 (First surface of the porous layer) 22 (The second surface of the porous layer) 23 holes 31 Adhesive 40 Laser processing machines 600 Single-lens reflex digital camera (imaging device) 601 Lens barrel (optical instrument) 602 Camera body 604 Inner cylinder (support) 620 cabinets

Claims

1. A substrate having a first surface, A porous layer having multiple pores is provided on the first surface of the substrate, The surface of the porous layer is provided with a row of first protrusions, each of which is spaced apart in a first direction, The porous layer has a row of second protrusions, each consisting of multiple second protrusions spaced apart and parallel to the first protrusions, The interval between the first row of protrusions and the second row of protrusions, which is the average value of the interval between the first protrusion and the adjacent second protrusion in a second direction perpendicular to the first direction, is greater than the average value of the height of the first row of protrusions and the average value of the height of the second row of protrusions. An optical member characterized in that the length of the first row of protrusions in the second direction and the length of the second row of protrusions in the second direction are greater than the length of the porous layer in the second direction.

2. The optical member according to claim 1, wherein the distance between the first row of protrusions and the second row of protrusions in the second direction is three times or more the height of the first row of protrusions and the height of the second row of protrusions.

3. The optical member according to claim 1 or 2, wherein the length of the first row of protrusions in the second direction and the length of the second row of protrusions in the second direction are 100 μm or more.

4. The optical member according to any one of claims 1 to 3, wherein the porous layer and the first row of protrusions and the second row of protrusions are formed of the same material.

5. The optical member according to claim 4, wherein the porous layer and the first row of protrusions and the second row of protrusions are formed of urethane resin.

6. The optical member according to claim 4 or 5, wherein the substrate and the porous layer are formed of the same material.

7. The optical member according to any one of claims 1 to 6, wherein the first row of protrusions and the second row of protrusions are arranged in a straight line when viewed from above.

8. The optical member according to any one of claims 1 to 6, wherein the first row of protrusions and the second row of protrusions are each arranged on a curve when viewed from above.

9. The optical member according to any one of claims 1 to 8, having a row of third protrusions on the surface of the porous layer, each consisting of a plurality of third protrusions spaced apart in the second direction.

10. The porous layer further has a row of fourth protrusions, each consisting of a plurality of fourth protrusions spaced apart and parallel to the third protrusions, The optical member according to claim 9, wherein the distance between the third row of protrusions and the fourth row of protrusions in the first direction is greater than the height of the third row of protrusions and the height of the fourth row of protrusions.

11. The optical member according to claim 9 or 10, wherein, when viewed from above, at least a portion of the first row of protrusions intersects with the third row of protrusions.

12. The optical member according to any one of claims 1 to 11, wherein the substrate has a second surface facing the first surface, and an adhesive is provided on the second surface.

13. A preparation step of preparing a member having a base material having a first surface and a porous layer having a plurality of holes on the first surface of the base material, A processing step of providing the surface of the porous layer with a first row of protrusions, each consisting of a plurality of first protrusions spaced apart in a first direction, and a second row of protrusions, each consisting of a plurality of second protrusions spaced apart parallel to the first protrusions. It has, In the aforementioned processing step, the distance between the row of first protrusions and the row of second protrusions, which is the average value of the distance between the first protrusion and the adjacent second protrusion in a second direction perpendicular to the first direction, is set to be greater than the average value of the height of the row of first protrusions and the average value of the height of the row of second protrusions. A method for manufacturing an optical member, characterized in that the length of the first row of protrusions in the second direction and the length of the second row of protrusions in the second direction are greater than the length of the porous layer in the second direction.

14. The method for manufacturing an optical member according to claim 13, wherein the preparation step includes a substrate preparation step of preparing a substrate having a first surface, and a lamination step of providing a porous layer having a plurality of holes on the first surface of the substrate.

15. The method for manufacturing an optical member according to claim 13 or 14, wherein the processing step is performed using a laser.

16. An optical instrument comprising a housing and an optical system having at least one lens within the housing, At least one of the support for the lens and the housing has an optical member according to any one of claims 1 to 12, An optical device characterized in that the first row of protrusions and the second row of protrusions are provided on at least one inner wall side of the support and the housing.

17. The optical device according to claim 16, wherein the optical member is provided such that the optical axis of the optical system intersects with the first row of protrusions and the second row of protrusions.

18. An imaging device comprising a housing, an optical system having at least one lens within the housing, and an image sensor that receives light that has passed through the optical system, At least one of the support for the lens and the housing has an optical member according to any one of claims 1 to 12, An imaging device characterized in that the first row of protrusions and the second row of protrusions are provided on at least one inner wall side of the support and the housing.

19. The imaging apparatus according to claim 18, wherein the optical member is provided such that the optical axis of the optical system intersects with the first row of protrusions and the second row of protrusions.

Images