Optical element, and method for manufacturing an optical element

Abstract

To provide an optical element that can suppress a decrease in image quality even when the optical element is miniaturized. [Solution] An optical element 1 according to one aspect of the present disclosure comprises a transparent substrate 10 and a light-shielding layer 11 formed around the outer edge of the optically effective surface 13 of the transparent substrate 10. The light-shielding layer 11 comprises a first light-shielding portion 21 provided on the outer edge and a second light-shielding portion 22 provided on the central side of the optically effective surface 13 than the first light-shielding portion 21.

Description

Technical Field

[0001] The present disclosure relates to an optical element and a method for manufacturing an optical element.

Background Art

[0002] In recent years, with the miniaturization of imaging devices such as smartphones, digital cameras, and video cameras, the optical elements used in these devices have also been miniaturized. Patent Document 1 discloses a technique related to an ND (Neutral Density) filter used for light quantity adjustment.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described in the background art, in recent years, with the miniaturization of imaging devices such as smartphones, digital cameras, and video cameras, the optical elements used in these devices have also been miniaturized. That is, in order to miniaturize the imaging device, it is necessary to narrow the space for arranging each optical element, and accordingly, each optical element is also miniaturized. However, when the optical element is miniaturized, there is a problem that the image quality of the image captured by the imaging device deteriorates.

[0005] In view of the above problems, an object of the present disclosure is to provide an optical element and a method for manufacturing an optical element capable of suppressing a decrease in image quality even when the optical element is miniaturized.

Means for Solving the Problems

[0006] An optical element according to one aspect of the present disclosure is an optical element comprising a transparent substrate and a light-shielding layer formed around the outer edge of the optically effective surface of the transparent substrate, wherein the light-shielding layer comprises a first light-shielding portion provided on the outer edge and a second light-shielding portion provided on the central side of the optically effective surface than the first light-shielding portion.

[0007] A method for manufacturing an optical element according to one aspect of the present disclosure comprises the steps of preparing a transparent substrate which is an optical element, and forming a light-shielding layer on the outer edge side of the optically effective surface of the transparent substrate, wherein the step of forming the light-shielding layer includes the steps of forming a first light-shielding portion on the outer edge side of the transparent substrate and forming a second light-shielding portion on the central side of the optically effective surface relative to the first light-shielding portion. [Effects of the Invention]

[0008] This disclosure provides an optical element that can suppress a decrease in image quality even when the optical element is miniaturized, and a method for manufacturing the optical element. [Brief explanation of the drawing]

[0009] [Figure 1] This is a front view illustrating an example of the configuration of an optical element according to an embodiment. [Figure 2] This is a side view illustrating an example of the configuration of an optical element according to an embodiment. [Figure 3] This is a side view illustrating an example of the configuration of an optical element according to an embodiment. [Figure 4] This graph illustrates the gradient state of the second light-shielding section. [Figure 5] This is a front view illustrating another example of the configuration of the optical element according to the embodiment. [Figure 6] This is a front view illustrating another example of the configuration of the optical element according to the embodiment. [Figure 7] This is a front view illustrating another example of the configuration of the optical element according to the embodiment. [Figure 8] This is a front view illustrating another example of the configuration of the optical element according to the embodiment. [Figure 9] It is a front view for explaining another configuration example of the optical element according to the embodiment. [Figure 10] It is a front view for explaining another configuration example of the optical element according to the embodiment. [Figure 11] It is a front view for explaining another configuration example of the optical element according to the embodiment. [Figure 12] It is a front view for explaining another configuration example of the optical element according to the embodiment. [Figure 13] It is a front view for explaining another configuration example of the optical element according to the embodiment. [Figure 14] It is a front view for explaining another configuration example of the optical element according to the embodiment. [Figure 15] It is a front view for explaining another configuration example of the optical element according to the embodiment. [Figure 16] It is a front view for explaining another configuration example of the optical element according to the embodiment. [Figure 17] It is a front view for explaining another configuration example of the optical element according to the embodiment. [Figure 18] It is a front view for explaining another configuration example of the optical element according to the embodiment. [Figure 19] It is a front view for explaining another configuration example of the optical element according to the embodiment.

Mode for Carrying Out the Invention

[0010] Hereinafter, the present disclosure will be described with reference to the drawings. FIG. 1 is a front view for explaining a configuration example of an optical element according to an embodiment. As shown in FIG. 1, the optical element 1 according to the present embodiment includes a transparent substrate 10 and a light shielding layer 11 formed around the outer edge side of the optical effective surface 13 of the transparent substrate 10. The light shielding layer 11 includes a first light shielding portion 21 provided on the outer edge side and a second light shielding portion 22 provided closer to the center side of the optical effective surface 13 than the first light shielding portion 21.

[0011] FIG. 2 and FIG. 3 are side views for explaining a configuration example of an optical element according to an embodiment. The optical element according to the present embodiment may be a plate-like optical element 1_1 as shown in FIG. 2. In this case, the light-shielding layer 11 may be provided on at least one of the incident surface 41 and the exit surface 42 of the optical element 1_1. That is, the light-shielding layer 11 may be provided on both the incident surface 41 and the exit surface 42 of the optical element 1_1, or the light-shielding layer 11 may be provided on only one of the incident surface 41 and the exit surface 42. In the case of the plate-like optical element 1_1, the optical axis of the incident surface 41 and the optical axis of the exit surface 42 are the same optical axis 43.

[0012] Further, the optical element according to the present embodiment may be a prism-shaped optical element 1_2 as shown in FIG. 3. Also in this case, the light-shielding layer 11 may be provided on at least one of the incident surface 51 and the exit surface 52 of the optical element 1_2. That is, the light-shielding layer 11 may be provided on both the incident surface 51 and the exit surface 52 of the optical element 1_2, or the light-shielding layer 11 may be provided on only one of the incident surface 51 and the exit surface 52. In the case of the prism-shaped optical element 1_2, for example, the angle formed by the optical axis 55 of the incident surface 51 and the optical axis 56 of the exit surface 52 is 90 degrees.

[0013] The optical element 1 according to the present embodiment may be used as an aperture stop. Also in the case of the prism-shaped optical element 1_2, it may be used as a periscope. Note that the optical element 1 according to the present embodiment includes a transparent region without the light-shielding layer 11 at the center of the optically effective surface 13 as shown in FIG. 1. That is, the optical element 1 according to the present embodiment is an optical element different from an ND filter in which a light-shielding layer is formed at the center of the optically effective surface 13. Hereinafter, the optical element 1 according to the present embodiment will be described in detail.

[0014] As shown in Figure 1, the optical element 1 according to this embodiment comprises a transparent substrate 10 and a light-shielding layer 11 formed around the outer edge of the optically effective surface 13 of the transparent substrate 10. The transparent substrate 10 is made of a transparent material, such as a transparent resin material or a glass material. Examples of resin materials include polyethylene terephthalate, cellophane, celluloid, polycarbonate, polyimide, polyvinyl chloride, polyacrylate, polyethylene, and polypropylene. In this embodiment, the material constituting the transparent substrate 10 is not limited to the above materials, and any material may be used as long as it satisfies predetermined optical and mechanical properties.

[0015] As shown in Figure 1, the light-shielding layer 11 comprises a first light-shielding portion 21 provided on the outer edge side and a second light-shielding portion 22 provided closer to the center of the optically effective surface 13 than the first light-shielding portion 21. For example, the transparent substrate 10 is rectangular when viewed from above, and the first light-shielding portion 21 is formed in a frame shape on the outer edge side of the optically effective surface 13 of the transparent substrate 10. The second light-shielding portion 22 is formed in a frame shape inside the first light-shielding portion 21. Although Figure 1 illustrates the case where the shape of the transparent substrate 10 when viewed from above is rectangular, the shape of the transparent substrate 10 when viewed from above may be circular or elliptical. In this case, the first light-shielding portion 21 and the second light-shielding portion 22 may be formed to follow the shape of the outer edge of the transparent substrate 10 (i.e., circular or elliptical).

[0016] In this embodiment, it is preferable that the transmission density of the second light-shielding portion 22 be lower than that of the first light-shielding portion 21. For example, the transmission density of the first light-shielding portion 21 is preferably 2.20 to 4.20, more preferably 2.60 to 4.20, and even more preferably 3.00 to 4.20. The transmission density of the second light-shielding portion 22 is preferably 0.10 to 2.00, more preferably 0.15 to 1.90, and even more preferably 0.20 to 1.80. The difference between the transmission density of the first light-shielding portion 21 and the transmission density of the second light-shielding portion 22 is preferably 1.00 to 3.00, more preferably 1.25 to 2.75, and even more preferably 1.50 to 2.50.

[0017] Here, optical density (OD) is a value measured using an optical densitometer, and is expressed logarithmically as the ratio of the value when a vertical transmitted light beam is irradiated onto the first light-shielding section 21 and the second light-shielding section 22 to the value when the optical element 1 is absent.

[0018] In this embodiment, the area ratio of the first light-shielding portion 21 on the optically effective surface 13 is preferably 20% to 75%, more preferably 30% to 70%, and even more preferably 40% to 65%. The area ratio of the second light-shielding portion 22 on the optically effective surface 13 is preferably 5% to 70%, more preferably 7% to 60%, and even more preferably 10% to 50%. Here, the optically effective surface 13 is the surface of the optical element 1 including the light-shielding layer 11 formed around the outer edge of the transparent substrate 10.

[0019] Furthermore, in this embodiment, the length in the horizontal direction X and the length in the vertical direction Y of the optical element 1 shown in Figure 1 can be any value depending on the optical system into which the optical element 1 is incorporated.

[0020] In this embodiment, the length of the first light-shielding portion 21 in the horizontal direction X1 shown in Figure 1 (i.e., the width X1 of one side of the frame-shaped first light-shielding portion 21 extending in the vertical direction) is preferably 5% to 60%, more preferably 10% to 55%, and even more preferably 15% to 50%, based on the length of the optical element 1 in the horizontal direction X. Furthermore, the length of the first light-shielding portion 21 in the vertical direction Y1 (i.e., the width Y1 of one side of the frame-shaped first light-shielding portion 21 extending in the horizontal direction) is preferably 5% to 60%, more preferably 10% to 55%, and even more preferably 15% to 50%, based on the length of the optical element 1 in the vertical direction Y.

[0021] In this embodiment, the length of the second light-shielding portion 22 in the horizontal direction X2 shown in Figure 1 (i.e., the width X2 of one side of the frame-shaped second light-shielding portion 22 extending in the vertical direction) is preferably 2% to 40%, more preferably 3% to 35%, and even more preferably 5% to 30%, based on the length of the optical element 1 in the horizontal direction X. Furthermore, the length of the second light-shielding portion 22 in the vertical direction Y2 (i.e., the width Y2 of one side of the frame-shaped second light-shielding portion 22 extending in the horizontal direction) is preferably 2% to 40%, more preferably 3% to 35%, and even more preferably 5% to 30%, based on the length of the optical element 1 in the vertical direction Y.

[0022] In this embodiment, the second light-shielding portion 22 may be configured such that the transmission density gradually increases from the center of the optically effective surface 13 toward the first light-shielding portion 21. In other words, the second light-shielding portion 22 may be configured in a gradient manner such that the transmission density gradually increases toward the first light-shielding portion 21.

[0023] Thus, when the second light-shielding portion 22 is in a gradient shape, the transmittance density on the first light-shielding portion 21 side of the second light-shielding portion 22 is preferably 2.20 or more and 4.20 or less, more preferably 2.60 or more and 4.20 or less, and even more preferably 3.00 or more and 4.20 or less. Furthermore, the transmittance density on the central side of the optically effective surface 13 of the second light-shielding portion 22 is preferably 0.10 or more and 1.05 or less, more preferably 0.15 or more and 1.00 or less, and even more preferably 0.20 or more and 0.95 or less.

[0024] Furthermore, if the second light-shielding portion 22 is gradient-shaped, the second light-shielding portion 22 may be configured such that the graph showing the rate of change in transmittance with respect to the position of the second light-shielding portion 22 changes in a convex shape downwards from the center of the optically effective surface 13 toward the first light-shielding portion 21. Figure 4 is a graph illustrating the gradient state of the second light-shielding portion 22, and is a graph showing the rate of change in transmittance (OD value) with respect to the gradient region (position) of the second light-shielding portion 22.

[0025] In this embodiment, the second light-shielding portion 22 may be configured such that the graph showing the rate of change in transmittance density (y-axis) with respect to the position (x-axis) of the second light-shielding portion 22 changes in a downward convex shape from the center of the optically effective surface 13 toward the first light-shielding portion 21. For example, a downward convex shape occurs when the rate of change in transmittance density (OD value) is 50% when the graph has advanced 80% from the center of the optically effective surface 13 toward the first light-shielding portion 21.

[0026] In this embodiment, the second light-shielding portion 22 may be configured such that the graph showing the rate of change in transmittance density (y-axis) with respect to the position (x-axis) of the second light-shielding portion 22 is a straight line. Alternatively, the second light-shielding portion 22 may be configured such that the graph showing the rate of change in transmittance density (y-axis) with respect to the position (x-axis) of the second light-shielding portion 22 changes in a convex shape upward from the center of the optical effective surface 13 toward the first light-shielding portion 21. For example, a convex shape upward is when the rate of change in transmittance density (OD value) is 50% when moving 20% ​​from the center of the optical effective surface 13 toward the first light-shielding portion 21.

[0027] Furthermore, with respect to the first light-shielding portion 21, it is preferable that the difference between the transmittance density on the outer edge side and the transmittance density on the second light-shielding portion 22 side be 0.20 or less. In other words, it is preferable that the transmittance density of the first light-shielding portion 21 is uniform, without any unevenness.

[0028] In this embodiment, the second light-shielding portion 22 may be composed of multiple dot patterns. That is, the gradation of the second light-shielding portion 22 may be composed of multiple dot patterns. For example, the second light-shielding portion 22 may be configured such that the density of multiple dot patterns gradually increases from the center side of the optically effective surface 13 toward the first light-shielding portion 21 side. The state of the gradation (shading) can be changed by adjusting the density of the dot patterns.

[0029] In this embodiment, it is preferable that the coverage rate of the first light-shielding portion 21 be 100%. Here, coverage rate refers to the percentage covered by the light-shielding layer. For example, the coverage rate may be adjusted by changing the density of the dot pattern. Furthermore, it is preferable that the coverage rate of the second light-shielding portion 22 be 80% or more, more preferably 90% or more, and even more preferably 95% or more.

[0030] Furthermore, in this embodiment, the first light-shielding portion 21 and the second light-shielding portion 22 may be formed using ink. For example, the first light-shielding portion 21 may be made using a first ink, and the second light-shielding portion 22 may be made using a second ink having at least a lower concentration of colorant than the first ink. Alternatively, for example, the first light-shielding portion 21 and the second light-shielding portion 22 may be made using a first ink. For example, the first ink and the second ink can use colorants such as carbon black, binder resins, solvents, etc.

[0031] Next, a method for manufacturing an optical element according to this embodiment will be described. When manufacturing the optical element according to this embodiment, first, a transparent substrate 10, which is the optical element, is prepared. The transparent substrate 10 can be made from the materials described above. When manufacturing a plate-shaped optical element 1_1, a plate-shaped transparent substrate 10 is prepared. When manufacturing a prism-shaped optical element 1_2, a prism-shaped transparent substrate 10 is prepared.

[0032] Next, a light-shielding layer 11 is formed on the outer edge side of the optically effective surface 13 of the transparent substrate 10. The step of forming the light-shielding layer 11 includes the step of forming a first light-shielding portion 21 on the outer edge side of the transparent substrate 10, and the step of forming a second light-shielding portion 22 on the central side of the optically effective surface 13, relative to the first light-shielding portion 21.

[0033] The light-shielding layer 11 can be formed using, for example, printing technology. For example, the light-shielding layer 11 can be formed using electrostatic coating printing, inkjet printing, electrophotographic printing, intaglio printing, etc. Among these, it is preferable to form the light-shielding layer 11 using inkjet technology. That is, when using inkjet technology, the density of the ink dot pattern can be easily adjusted, so the transmittance density and gradation state of the light-shielding layer 11 can be easily adjusted.

[0034] As explained in the background technology section, in recent years, with the miniaturization of imaging devices such as smartphones, digital cameras, and video cameras, the optical elements used in them have also become smaller. In other words, in order to miniaturize imaging devices, it is necessary to reduce the space in which each optical element is arranged, and consequently, each optical element has become smaller. However, miniaturizing optical elements has the problem of degrading the image quality of images captured by imaging devices.

[0035] In the optical element 1 according to this embodiment, a light-shielding layer 11 is formed around the outer edge of the optically effective surface 13 of the transparent substrate 10. The light-shielding layer 11 comprises a first light-shielding portion 21 provided on the outer edge side and a second light-shielding portion 22 provided closer to the center of the optically effective surface 13 than the first light-shielding portion 21. With this configuration, it is possible to provide an optical element that can suppress a decrease in image quality even when the optical element is miniaturized, and a method for manufacturing the optical element.

[0036] In particular, when optical elements are miniaturized, there is a problem in that fish-scale-like patterns or cross-shaped patterns appear in the image captured by the imaging device, resulting in a decrease in image quality. In this embodiment, since the first light-shielding portion 21 is provided on the outer edge side of the transparent substrate 10, the appearance of fish-scale-like patterns in the captured image can be suppressed. Furthermore, since the second light-shielding portion 22 is provided closer to the center of the optically effective surface 13 than the first light-shielding portion 21, the appearance of cross-shaped patterns in the captured image can be suppressed. In addition, with the above configuration, the optical element 1 according to this embodiment can suppress the occurrence of iridescent patterns (rainbow-like patterns) and corner patterns (anger-like patterns).

[0037] Next, other configuration examples of the optical element according to this embodiment will be described. Figures 5 to 19 are front views illustrating other configuration examples of the optical element according to this embodiment.

[0038] In this embodiment, as shown in Figure 5, the second light-shielding portion 22a may have a first region 31 and a second region 32. The first region 31 is a region arranged adjacent to the first light-shielding portion 21. The second region 32 is a region arranged adjacent to the first region 31, on the central side of the optically effective surface 13 with respect to the first region 31. In this case, it is preferable that the transmission density of the first region 31 be higher than the transmission density of the second region 32. The other configurations are the same as those of the optical element 1 shown in Figure 1.

[0039] In the configuration shown in Figure 5, the area ratio of the first region 31 in the second light-shielding portion 22a is preferably 25% to 75%, more preferably 30% to 70%, and even more preferably 35% to 65%. Furthermore, the area ratio of the second region 32 in the second light-shielding portion 22a is preferably 25% to 75%, more preferably 30% to 70%, and even more preferably 35% to 65%.

[0040] The first region 31 and the second region 32 of the second light-shielding portion 22a may be formed using two types of ink. For example, if the concentration of the colorant in the second ink is lower than the concentration of the colorant in the first ink (in other words, if the first ink is darker than the second ink), the first region 31 may be formed using the first ink and the second region 32 may be formed using the second ink.

[0041] In this embodiment, as shown in Figure 6, the second light-shielding portion 22b may have a first region 31, a second region 32, and a third region 33. The first region 31 is a region arranged adjacent to the first light-shielding portion 21. The second region 32 is a region arranged adjacent to the first region 31, on the central side of the optically effective surface 13 with respect to the first region 31. The third region 33 is a region arranged adjacent to the second region 32, on the central side of the optically effective surface 13 with respect to the second region 32. In this case, it is preferable to configure the optical element 1 as shown in Figure 1 such that the transmission density of the first region 31 is higher than that of the second region 32, and the transmission density of the second region 32 is higher than that of the third region 33. The other configurations are the same as those of the optical element 1 shown in Figure 1.

[0042] In the configuration shown in Figure 6, the area ratio of the first region 31 in the second light-shielding portion 22b is preferably 10% to 80%, more preferably 15% to 75%, and even more preferably 20% to 70%. Furthermore, the area ratio of the second region 32 in the second light-shielding portion 22b is preferably 10% to 80%, more preferably 15% to 75%, and even more preferably 20% to 70%. Furthermore, the area ratio of the third region 33 in the second light-shielding portion 22b is preferably 10% to 80%, more preferably 15% to 75%, and even more preferably 20% to 70%.

[0043] The first region 31, the second region 32, and the third region 33 of the second light-shielding portion 22b may be formed using two types of ink. For example, if the concentration of the colorant in the second ink is lower than the concentration of the colorant in the first ink (in other words, if the first ink is darker than the second ink), the first region 31 may be formed using the first ink, the second region 32 may be formed using both the first and second inks (for example, by overlapping the first and second inks at a predetermined pattern density), and the third region 33 may be formed using the second ink. Note that this formation method is just one example, and the regions and proportions in which the first and second inks are used may be appropriately determined according to the transmittance (OD value) in each region.

[0044] In this embodiment, as shown in Figure 7, the shape of the central side of the optically effective surface 13 of the second light-shielding portion 22c may be a rounded square shape with rounded corners. The other configurations are the same as those of the optical element 1 shown in Figure 1.

[0045] Furthermore, in this embodiment, the configuration shown in Figure 5 and the configuration shown in Figure 7 may be combined. Specifically, as shown in Figure 8, the shape of the central side of the optically effective surface 13 of the second light-shielding portion 22d, which has a first region 31d and a second region 32d, may be a rounded square shape with rounded corners.

[0046] In this embodiment, as shown in Figure 9, the optical element 1e, the second light-shielding portion 22e may have a first region 31e, a second region 32e, a third region 33e, and a fourth region 34e. The first region 31e is a region arranged adjacent to the first light-shielding portion 21. The second region 32e is a region arranged adjacent to the first region 31e, on the central side of the optically effective surface 13 with respect to the first region 31e. The third region 33e is a region arranged adjacent to the second region 32e, on the central side of the optically effective surface 13 with respect to the second region 32e. The fourth region 34e is a region arranged adjacent to the third region 33e, on the central side of the optically effective surface 13 with respect to the third region 33e. In this case, it is preferable to configure the system so that the transmission density of the first region 31e is higher than that of the second region 32e, the transmission density of the second region 32e is higher than that of the third region 33e, and the transmission density of the third region 33e is higher than that of the fourth region 34e. The other configurations are the same as those of the optical element 1 shown in Figure 1. Figure 9 also shows an example configuration in which the central shape of the optically effective surface 13 of the second light-shielding portion 22e, which has the first to fourth regions 31e to 34e, is a rounded square shape with rounded corners.

[0047] In this embodiment, the shape of the central side of the optically effective surface 13 of the second light-shielding portion 22f may be elliptical, as shown in Figure 10 for the optical element 1f. Other configurations are the same as those of the optical element 1 shown in Figure 1.

[0048] Furthermore, in this embodiment, the configuration shown in Figure 5 and the configuration shown in Figure 10 may be combined. Specifically, as shown in Figure 11, the shape of the central side of the optical effective surface 13 of the second light-shielding portion 22g, which has a first region 31g and a second region 32g, may be elliptical. Similarly, in this embodiment, the configuration shown in Figure 9 and the configuration shown in Figure 10 may be combined. Specifically, as shown in Figure 12, the shape of the central side of the optical effective surface 13 of the second light-shielding portion 22h, which has a first region 31h, a second region 32h, a third region 33h, and a fourth region 34h, may be elliptical.

[0049] In this embodiment, as shown in Figure 13, the second light-shielding portion 22i may be formed at the four inner corners of the first light-shielding portion 21. The shape of the central side of the optical effective surface 13 of the light-shielding layer 11, including the first light-shielding portion 21 and the second light-shielding portion 22i, may be a rounded square shape with rounded corners. The other configurations are the same as those of the optical element 1 shown in Figure 1.

[0050] Furthermore, in this embodiment, the configuration shown in Figure 7 and the configuration shown in Figure 13 may be combined. Specifically, in a second light-shielding portion 22j having a first region 31j and a second region 32j, as shown in the optical element 1j in Figure 14, the first region 31j may be formed at the four inner corners of the first light-shielding portion 21, and the shape of the central side of the optical effective surface 13 of the second region 32j may be a rounded rectangle. Similarly, in this embodiment, the configuration shown in Figure 9 and the configuration shown in Figure 13 may be combined. Specifically, in a second light-shielding portion 22k having a first region 31k, a second region 32k, a third region 33k, and a fourth region 34k, as shown in the optical element 1k in Figure 15, the first region 31k may be formed at the four inner corners of the first light-shielding portion 21, and the shape of the central side of the optical effective surface 13 of the second region 32k to the fourth region 34k may be a rounded rectangle.

[0051] In this embodiment, as shown in Figure 16, the second light-shielding portion 22m may have a plurality of convex shapes 25 on the central side of the optically effective surface 13 of the second light-shielding portion 22m. The other configurations are the same as those of the optical element 1 shown in Figure 1.

[0052] Furthermore, in this embodiment, the configuration shown in Figure 5 and the configuration shown in Figure 16 may be combined. Specifically, as shown in Figure 17, an additional convex shape 26 may be formed on the central side of the optical effective surface 13 of the convex shape 25 of the second light-shielding portion 22n. In other words, multiple convex shapes 25 and 26 may be formed to overlap. In this case, the second light-shielding portion 22n has a first region 31n having a convex shape 25 and a second region 32n having a convex shape 26.

[0053] Furthermore, in this embodiment, the configuration shown in Figure 9 and the configuration shown in Figure 16 may be combined. Specifically, as shown in Figure 18, as in the optical element 1p, further convex shapes 26, 27, and 28 may be formed on the central side of the optical effective surface 13 of the convex shape 25 of the second light-shielding portion 22p. In other words, the four convex shapes 25, 26, 27, and 28 may be formed to overlap. In this case, the second light-shielding portion 22p may have a first region 31p with a convex shape 25, a second region 32p with a convex shape 26, a third region 33p with a convex shape 27, and a fourth region 34p with a convex shape 28.

[0054] Furthermore, in this embodiment, as shown in Figure 19, the second light-shielding portion 22q may include a first region 61, a second region 62, a third region 63, and a fourth region 64 having multiple convex shapes on the central side of the optically effective surface 13 of the second light-shielding portion 22q. In other words, a first region 61 having a convex shape may be formed, and further, a second region 62, a third region 63, and a fourth region 64 having convex shapes may be formed on the central side of the optically effective surface 13 of the second light-shielding portion 22q. To put it another way, a part of the convex shape 25 of the optical element 1m shown in Figure 16 may be replaced with a second region 62, a third region 63, and a fourth region 64, each having different transmission density (OD value).

[0055] Although other configuration examples of the optical element according to this embodiment have been described above using Figures 5 to 19, the optical element according to this embodiment may have any configuration as long as the light-shielding layer 11 has a first light-shielding portion 21 and a second light-shielding portion 22. [Examples]

[0056] Next, we will describe some examples. In this embodiment, an optical element equipped with a light-shielding layer 11 was formed, and the effect of the light-shielding layer 11 on image quality was investigated. Specifically, a plate-shaped optical element 1_1 shown in Figure 2 was fabricated as a sample, the fabricated optical element 1_1 was incorporated into the optical system of an imaging device, and an image of a subject was captured using the imaging device to evaluate the image quality.

[0057] In this embodiment, a light-shielding layer 11 was provided on the light-receiving surface 41 of the optical element 1_1. The light-shielding layer 11 was formed using inkjet technology. Specifically, an inkjet device (VJ-1628MH, manufactured by Mutoh Industries, Ltd.) was used, and the following inks 1 and / or 2 were used. Here, ink 1 (black ink) is a dark ink, and ink 2 (light black ink) is a light ink. • Ink 1: Black ink (MP31-BK220U) • Ink 2: Light Black Ink (MP31-LK220U)

[0058] The configuration of each sample is as follows:

[0059] <Example 1> As a sample according to Example 1, an optical element comprising a first light-shielding portion 21 and a second light-shielding portion 22 was formed (see Figure 1). The inner frame shape of the first light-shielding portion 21 was rectangular. The size of the first light-shielding portion 21 was standard size (STD). Here, standard size (STD) means that the length of the first light-shielding portion 21 in the horizontal direction X1 is 1.20 mm and the length of the vertical direction Y1 is 1.05 mm, as shown in Figure 1. The length of the optical element in the horizontal direction X was 7.60 mm and the length of the vertical direction Y was 5.70 mm. The area ratio of the first light-shielding portion 21 on the optically effective surface 13 (see Figure 1) was 57%. The coverage rate of a certain area of ​​the first light-shielding portion 21 was 100%. The transmittance density (OD value) of the first light-shielding portion 21 was 3.2. The first light-shielding portion 21 was formed using ink 1.

[0060] The size of the second light-shielding section 22 was set to the standard size (STD). Here, the standard size (STD) is defined as the length of the second light-shielding section 22 in the horizontal direction X2 being 0.42 mm and the length of the vertical direction Y2 being 0.30 mm, as shown in Figure 1. The dot pattern of the second light-shielding section 22 was set to solid (applied to the entire surface). The area ratio of the second light-shielding section 22 on the optically effective surface 13 (see Figure 1) was set to 13%. The coverage rate of a certain area of ​​the second light-shielding section 22 was set to 100%. The transmittance density (OD value) of the second light-shielding section 22 was set to 0.30. The second light-shielding section 22 was formed using ink 2.

[0061] <Example 2> As a sample for Example 2, a sample was prepared in which the second light-shielding portion 22b had three regions: a first region 31, a second region 32, and a third region 33, as shown in Figure 6 (optical element 1b). Specifically, the area ratios of the first region 31, the second region 32, and the third region 33 in the second light-shielding portion 22 were set to 36%, 33%, and 31%, respectively. The OD values ​​of the first region 31, the second region 32, and the third region 33 in the second light-shielding portion 22 were set to 1.25, 0.65, and 0.30, respectively. The second light-shielding portion 22 was formed using ink 1 and ink 2. Specifically, the first region 31 was formed using ink 1 and ink 2, the second region 32 was formed using ink 2 (200%), and the third region 33 was formed using ink 2 (100%). The OD values ​​for each region were adjusted by changing the density of the dot patterns of ink 1 and ink 2. In other words, ink 2 (200%) has twice the dot pattern density of ink 2 (100%) (the same applies hereafter). The other configurations were the same as those of the sample in Example 1.

[0062] <Example 3> As a sample for Example 3, a sample was prepared in which the size of the first light-shielding portion 21 was smaller than the standard size (STD), and the size of the second light-shielding portion 22 was larger than the standard size (STD). Specifically, the length of the first light-shielding portion 21 in the horizontal direction X1 shown in Figure 1 was set to 0.70 mm, and the length of the vertical direction Y1 was set to 0.55 mm, so that the area ratio of the first light-shielding portion 21 on the optically effective surface 13 was 34%. Also, the length of the second light-shielding portion 22 in the horizontal direction X2 shown in Figure 1 was set to 0.92 mm, and the length of the vertical direction Y2 was set to 0.80 mm, so that the area ratio of the second light-shielding portion 22 on the optically effective surface 13 was 36%. The other configurations were the same as those of the sample for Example 1.

[0063] <Example 4> As a sample for Example 4, a sample was prepared in which the size of the first light-shielding portion 21 was the standard size (STD), and the size of the second light-shielding portion 22 was larger than the standard size (STD). Specifically, the length of the second light-shielding portion 22 in the horizontal direction X2 shown in Figure 1 was set to 1.42 mm, the length of the vertical direction Y2 was set to 1.30 mm, and the area ratio of the second light-shielding portion 22 on the optically effective surface 13 was set to 38%. The other configurations were the same as those of the sample for Example 1.

[0064] <Example 5> As a sample for Example 5, a sample was prepared in which the size of the first light-shielding portion 21 was smaller than the standard size (STD), and the size of the second light-shielding portion 22 was larger than the standard size (STD). Specifically, the length of the first light-shielding portion 21 in the horizontal direction X1 shown in Figure 1 was set to 0.70 mm, and the length of the vertical direction Y1 was set to 0.55 mm, so that the area ratio of the first light-shielding portion 21 on the optically effective surface 13 was 34%. Also, the length of the second light-shielding portion 22 in the horizontal direction X2 shown in Figure 1 was set to 1.92 mm, and the length of the vertical direction Y2 was set to 1.80 mm, so that the area ratio of the second light-shielding portion 22 on the optically effective surface 13 was 61%. The other configurations were the same as those of the sample for Example 1.

[0065] <Example 6> As a sample for Example 6, a sample was prepared in which the second light-shielding portion 22 had a gradient (GD) shape. Specifically, the OD value of the second light-shielding portion 22 on the side of the first light-shielding portion 21 was set to 3.2, and the OD value on the central side of the optically effective surface 13 of the second light-shielding portion 22 was set to 0.15, so that the OD value of the gradient region changed linearly (see Figure 4). The coverage rate of a certain range of the second light-shielding portion 22 was set to 85%. The second light-shielding portion 22 was formed using ink 1 and ink 2. The other configurations were the same as those of the sample for Example 1.

[0066] <Example 7> As a sample for Example 7, a sample was prepared in which the second light-shielding portion 22 had a gradient shape. Specifically, the OD value of the second light-shielding portion 22 on the side of the first light-shielding portion 21 was set to 3.2, and the OD value of the central side of the optically effective surface 13 of the second light-shielding portion 22 was set to 0.30, so that the OD value of the gradient region changed linearly (see Figure 4). The coverage rate of a certain range of the second light-shielding portion 22 was set to 100%. The second light-shielding portion 22 was formed using ink 1 and ink 2. The other configurations were the same as those of the sample for Example 1.

[0067] <Example 8> As a sample for Example 8, a sample was prepared in which the second light-shielding portion 22 of the sample from Example 5 was made to have a gradient shape. Specifically, the OD value of the second light-shielding portion 22 on the side of the first light-shielding portion 21 was set to 3.2, and the OD value on the central side of the optically effective surface 13 of the second light-shielding portion 22 was set to 0.30, so that the OD value of the gradient region changed linearly (see Figure 4). The second light-shielding portion 22 was formed using ink 1 and ink 2. The other configurations were the same as those of the sample from Example 5.

[0068] <Example 9> As a sample for Example 9, a sample was prepared in which the second light-shielding portion 22 of the sample from Example 5 was made into a gradient. Specifically, the OD value of the second light-shielding portion 22 on the side of the first light-shielding portion 21 was set to 3.2, and the OD value of the second light-shielding portion 22 on the central side of the optically effective surface 13 was set to 0.30, so that the OD value of the gradient region changed to be convex upward from the central side of the optically effective surface 13 toward the first light-shielding portion 21 (see Figure 4). The second light-shielding portion 22 was formed using ink 1 and ink 2. The other configurations were the same as those of the sample from Example 5.

[0069] <Example 10> As a sample for Example 10, a sample was prepared in which the second light-shielding portion 22 of the sample for Example 5 was made into a gradient. Specifically, the OD value of the second light-shielding portion 22 on the side of the first light-shielding portion 21 was set to 3.2, and the OD value of the second light-shielding portion 22 on the central side of the optically effective surface 13 was set to 0.30, so that the OD value of the gradient region changed to be convex downward from the central side of the optically effective surface 13 toward the first light-shielding portion 21 (see Figure 4). The second light-shielding portion 22 was formed using ink 1 and ink 2. The other configurations were the same as those of the sample for Example 5.

[0070] <Example 11> As a sample for Example 11, an optical element 1i having the configuration shown in Figure 13 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. The second light-shielding portion 22i was formed at the four inner corners of the first light-shielding portion 21. At this time, the area ratio of the second light-shielding portion 22i on the optically effective surface 13 (see Figure 13) was set to 2%. The coverage rate of a certain area of ​​the second light-shielding portion 22i was set to 100%. The OD value of the second light-shielding portion 22i was set to 3.20. The second light-shielding portion 22i was formed using ink 1. The other configurations were the same as the sample for Example 1.

[0071] <Example 12> As a sample for Example 12, an optical element 1j having the configuration shown in Figure 14 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. The second light-shielding portion 22j comprises a first region 31j and a second region 32j, with the length of the second light-shielding portion 22j in the lateral direction X2 being 0.38 mm and the length of the vertical direction Y2 being 0.28 mm. The area ratio of the second light-shielding portion 22j on the optically effective surface 13 (see Figure 14) was 13%. The area ratios of the first region 31j and the second region 32j in the second light-shielding portion 22j were 15% and 85%, respectively. The OD values ​​of the first region 31j and the second region 32j in the second light-shielding portion 22j were 3.20 and 0.30, respectively. The first region 31j was formed using ink 1, and the second region 32j was formed using ink 2. The OD values ​​for each region were adjusted by changing the density of the dot patterns of ink 1 and ink 2. All other configurations were the same as those of the sample in Example 1.

[0072] <Example 13> As a sample for Example 13, an optical element 1k having the configuration shown in Figure 15 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. The second light-shielding portion 22k comprises a first region 31k, a second region 32k, a third region 33k, and a fourth region 34k, with the length of the second light-shielding portion 22j in the lateral direction X2 being 0.38 mm and the length of the vertical direction Y2 being 0.28 mm. The area ratio of the second light-shielding portion 22k on the optically effective surface 13 (see Figure 15) was 13%. The area ratios of the first region 31k, second region 32k, third region 33k, and fourth region 34k in the second light-shielding portion 22k were 15%, 31%, 28%, and 26%, respectively. The OD values ​​of the first region 31k, second region 32k, third region 33k, and fourth region 34k of the second light-shielding section 22k were set to 3.20, 1.25, 0.65, and 0.30, respectively. The first region 31k was formed using ink 1, the second region 32k was formed using ink 1 (75%) and ink 2 (75%), the third region 33k was formed using ink 2 (200%), and the fourth region 34k was formed using ink 2 (100%). The other components were the same as those of the sample in Example 1.

[0073] <Example 14> As a sample for Example 14, a sample was prepared in which the second region 32j of the optical element 1j having the configuration shown in Figure 14 was made into a gradient. Specifically, the OD value of the second region 32j of the second light-shielding portion 22j on the first light-shielding portion 21 side was set to 3.2, and the OD value on the central side of the optically effective surface 13 of the second region 32j was set to 0.30, so that the OD value of the gradient region was changed linearly (see Figure 4). The other configurations were the same as those of the sample for Example 12.

[0074] <Example 15> As a sample for Example 15, an optical element 1c having the configuration shown in Figure 7 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. The shape of the central side of the optical effective surface 13 of the second light-shielding portion 22c was a rounded rectangle. The length of the second light-shielding portion 22c in the horizontal direction X2 was 0.21 mm, and the length of the vertical direction Y2 was 0.15 mm. The area ratio of the second light-shielding portion 22c on the optical effective surface 13 (see Figure 7) was 8%. The coverage rate of a certain area of ​​the second light-shielding portion 22c was 100%. The OD value of the second light-shielding portion 22c was 3.20. The second light-shielding portion 22c was formed using ink 1. The other configurations were the same as the sample for Example 1.

[0075] <Example 16> As a sample for Example 16, an optical element 1d having the configuration shown in Figure 8 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. The second light-shielding portion 22d comprises a first region 31d and a second region 32d, with the length of the second light-shielding portion 22d in the lateral direction X2 being 0.51 mm and the length of the vertical direction Y2 being 0.36 mm. The area ratio of the second light-shielding portion 22d on the optically effective surface 13 (see Figure 8) was 15%. The area ratios of the first region 31d and the second region 32d in the second light-shielding portion 22d were 66% and 34%, respectively. The OD values ​​of the first region 31d and the second region 32d in the second light-shielding portion 22d were 3.20 and 0.30, respectively. The first region 31d was formed using ink 1, and the second region 32d was formed using ink 2. The OD values ​​for each region were adjusted by changing the density of the dot patterns of ink 1 and ink 2. All other configurations were the same as those of the sample in Example 1.

[0076] <Example 17> As a sample for Example 17, an optical element 1e having the configuration shown in Figure 9 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. The second light-shielding portion 22e comprises a first region 31e, a second region 32e, a third region 33e, and a fourth region 34e. The length of the second light-shielding portion 22e in the lateral direction X2 was 0.51 mm, and the length in the vertical direction Y2 was 0.36 mm. The area ratio of the second light-shielding portion 22e on the optically effective surface 13 (see Figure 9) was 15%. The area ratios of the first region 31e, second region 32e, third region 33e, and fourth region 34e in the second light-shielding portion 22e were 66%, 15%, 11%, and 8%, respectively. The OD values ​​of the first region 31e, second region 32e, third region 33e, and fourth region 34e of the second light-shielding portion 22e were set to 3.20, 1.25, 0.65, and 0.30, respectively. The first region 31e was formed using ink 1, the second region 32e was formed using ink 1 (75%) and ink 2 (75%), the third region 33e was formed using ink 2 (200%), and the fourth region 34e was formed using ink 2 (100%). The other components were the same as those of the sample in Example 1.

[0077] <Example 18> As a sample for Example 18, a sample was prepared in which the second region 32c of the optical element 1c having the configuration shown in Figure 8 was made into a gradient. Specifically, the OD value of the second region 32c of the second light-shielding portion 22c on the first light-shielding portion 21 side was set to 3.2, and the OD value on the central side of the optically effective surface 13 of the second region 32c was set to 0.30, so that the OD value of the gradient region was changed linearly (see Figure 4). The other configurations were the same as those of the sample for Example 16.

[0078] <Example 19> As a sample for Example 19, an optical element 1f having the configuration shown in Figure 10 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. In addition, the shape of the central side of the optical effective surface 13 of the second light-shielding portion 22f was elliptical. The length of the second light-shielding portion 22f in the horizontal direction X2 was 0.08 mm, and the length of the vertical direction Y2 was 0.08 mm. The area ratio of the second light-shielding portion 22f on the optical effective surface 13 (see Figure 10) was 14%. The coverage rate of a certain area of ​​the second light-shielding portion 22f was 100%. The OD value of the second light-shielding portion 22f was 3.20. The second light-shielding portion 22f was formed using ink 1. The other configurations were the same as the sample for Example 1.

[0079] <Example 20> As a sample for Example 20, an optical element 1g having the configuration shown in Figure 11 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. The second light-shielding portion 22g comprises a first region 31g and a second region 32g, with the length of the second light-shielding portion 22g in the lateral direction X2 being 0.31 mm and the length of the vertical direction Y2 being 0.27 mm. The area ratio of the second light-shielding portion 22g on the optically effective surface 13 (see Figure 11) was 20%. The area ratios of the first region 31g and the second region 32g in the second light-shielding portion 22g were 85% and 15%, respectively. The OD values ​​of the first region 31g and the second region 32g in the second light-shielding portion 22g were 3.20 and 0.30, respectively. The first region 31g was formed using ink 1, and the second region 32g was formed using ink 2. The OD values ​​for each region were adjusted by changing the density of the dot patterns of ink 1 and ink 2. All other configurations were the same as those of the sample in Example 1.

[0080] <Example 21> As a sample for Example 21, an optical element 1h having the configuration shown in Figure 12 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. The second light-shielding portion 22h comprises a first region 31h, a second region 32h, a third region 33h, and a fourth region 34h. The length of the second light-shielding portion 22h in the lateral direction X2 was 0.31 mm, and the length in the vertical direction Y2 was 0.27 mm. The area ratio of the second light-shielding portion 22h on the optically effective surface 13 (see Figure 12) was 20%. The area ratios of the first region 31h, second region 32h, third region 33h, and fourth region 34h in the second light-shielding portion 22h were 85%, 7%, 5%, and 3%, respectively. The OD values ​​of the first region 31h, second region 32h, third region 33h, and fourth region 34h of the second light-shielding section 22h were set to 3.20, 1.25, 0.65, and 0.30, respectively. The first region 31h was formed using ink 1, the second region 32h was formed using ink 1 (75%) and ink 2 (75%), the third region 33h was formed using ink 2 (200%), and the fourth region 34h was formed using ink 2 (100%). The other components were the same as those of the sample in Example 1.

[0081] <Example 22> As a sample for Example 22, a sample was prepared in which the second region 32g of an optical element 1g having the configuration shown in Figure 11 was made into a gradient. Specifically, the OD value of the second region 32g of the second light-shielding portion 22g on the first light-shielding portion 21 side was set to 3.2, and the OD value on the central side of the optically effective surface 13 of the second region 32g was set to 0.30, so that the OD value of the gradient region was changed linearly (see Figure 4). The other configurations were the same as those of the sample for Example 20.

[0082] <Example 23> As a sample for Example 23, an optical element 1m having the configuration shown in Figure 16 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. The second light-shielding portion 22m had a shape with multiple convex shapes 25 on the central side of the optical effective surface 13 of the second light-shielding portion 22m. The length of the second light-shielding portion 22m in the horizontal direction X2 was 0.38 mm, and the length of the vertical direction Y2 was 0.28 mm. The area ratio of the second light-shielding portion 22m on the optical effective surface 13 (see Figure 10) was 10%. The coverage rate of a certain area of ​​the second light-shielding portion 22m was 100%. The OD value of the second light-shielding portion 22m was 3.20. The second light-shielding portion 22f was formed using ink 1. The other configurations were the same as the sample for Example 1.

[0083] <Example 24> As a sample for Example 24, an optical element 1n having the configuration shown in Figure 17 was fabricated. Specifically, a convex shape 26 was formed on the central side of the optical effective surface 13 of the convex shape 25 of the second light-shielding portion 22n. In other words, multiple convex shapes 25 and 26 were formed to overlap. The second light-shielding portion 22n has a first region 31n having the convex shape 25 and a second region 32n having the convex shape 26. The first light-shielding portion 21 had the same configuration as in Example 1. The length of the second light-shielding portion 22n in the horizontal direction X2 was 0.68 mm, and the length of the vertical direction Y2 was 0.50 mm. The area ratio of the second light-shielding portion 22n on the optical effective surface 13 (see Figure 17) was 17%. The area ratios of the first region 31n and the second region 32n in the second light-shielding portion 22n were 90% and 10%, respectively. The OD values ​​of the first region 31n and the second region 32n of the second light-shielding portion 22n were set to 3.20 and 0.30, respectively. The first region 31n was formed using ink 1, and the second region 32n was formed using ink 2. The OD values ​​of each region were adjusted by changing the density of the dot patterns of ink 1 and ink 2. The other configurations were the same as those of the sample in Example 1.

[0084] <Example 25> As a sample for Example 25, an optical element 1p having the configuration shown in Figure 18 was fabricated. Specifically, as shown in Figure 18, as with the optical element 1p, further convex shapes 26, 27, and 28 were formed on the central side of the optical effective surface 13 of the convex shape 25 of the second light-shielding portion 22p. The second light-shielding portion 22p has a first region 31p with the convex shape 25, a second region 32p with the convex shape 26, a third region 33p with the convex shape 27, and a fourth region 34p with the convex shape 28. The first light-shielding portion 21 had the same configuration as in Example 1.

[0085] The length of the second light-shielding portion 22p in the horizontal direction X2 was set to 0.68 mm, and the length of the vertical direction Y2 was set to 0.50 mm. The area ratio of the second light-shielding portion 22p on the optically effective surface 13 (see Figure 18) was set to 17%. The area ratios of the first region 31p, second region 32p, third region 33p, and fourth region 34p in the second light-shielding portion 22p were set to 90%, 5%, 3%, and 2%, respectively. The OD values ​​of the first region 31p, second region 32p, third region 33p, and fourth region 34p in the second light-shielding portion 22p were set to 3.20, 1.25, 0.65, and 0.30, respectively. The first region 31p was formed using ink 1, the second region 32p was formed using ink 1 (75%) and ink 2 (75%), the third region 33p was formed using ink 2 (200%), and the fourth region 34p was formed using ink 2 (100%). The other components were the same as those of the sample in Example 1.

[0086] <Example 26> As a sample for Example 26, a sample was prepared in which the second region 32n of the optical element 1n having the configuration shown in Figure 17 was made into a gradient. Specifically, the OD value of the second region 32n of the second light-shielding portion 22n on the first light-shielding portion 21 side was set to 3.2, and the OD value on the central side of the optically effective surface 13 of the second region 32n was set to 0.30, so that the OD value of the gradient region was changed linearly (see Figure 4). The other configurations were the same as those of the sample for Example 24.

[0087] <Example 27> As a sample for Example 27, an optical element 1q having the configuration shown in Figure 19 was fabricated. The first light-shielding portion 21 had the same configuration as in Example 1. The second light-shielding portion 22m had a shape with multiple convex shapes 25 on the central side of the optical effective surface 13 of the second light-shielding portion 22m. The length of the second light-shielding portion 22m in the horizontal direction X2 was 0.68 mm, and the length of the vertical direction Y2 was 0.50 mm. The area ratio of the second light-shielding portion 22m on the optical effective surface 13 (see Figure 10) was 17%. The coverage rate of a certain area of ​​the second light-shielding portion 22m was 100%. The OD value of the second light-shielding portion 22m was 3.20. The second light-shielding portion 22f was formed using ink 1. The other configurations were the same as the sample for Example 1. Furthermore, the second light-shielding portion 22q has a shape that includes a first region 61, a second region 62, a third region 63, and a fourth region 64, each having a convex shape, on the central side of the optically effective surface 13 of the second light-shielding portion 22q. In other words, a first region 61 with a convex shape is formed, and further, a second region 62, a third region 63, and a fourth region 64 with a convex shape are formed on the central side of the optically effective surface 13 of the second light-shielding portion 22q. The OD values ​​of the first region 61, the second region 62, the third region 63, and the fourth region 64 are each different.

[0088] <Comparative Example 1> As a sample for Comparative Example 1, a sample was prepared in which the first light-shielding portion 21 and the second light-shielding portion 22 were not formed.

[0089] <Comparative Example 2> As a sample for Comparative Example 2, a sample was prepared in which only the first light-shielding portion 21 was formed, and the second light-shielding portion 22 was not formed. In Comparative Example 2, the inner frame shape of the first light-shielding portion 21 was rectangular, and the size of the first light-shielding portion 21 was set to the standard size (STD). The area ratio of the first light-shielding portion 21 on the optically effective surface 13 was set to 57%. In addition, the coverage rate of a certain area of ​​the first light-shielding portion 21 was set to 80%. The transmittance density (OD value) of the first light-shielding portion 21 was set to 1.8.

[0090] <Comparative Example 3> As a sample for Comparative Example 3, a sample was prepared in which only the first light-shielding portion 21 was formed, and the second light-shielding portion 22 was not formed. In Comparative Example 3, the inner frame shape of the first light-shielding portion 21 was rectangular, and the size of the first light-shielding portion 21 was set to the standard size (STD). The area ratio of the first light-shielding portion 21 on the optically effective surface 13 was set to 57%. In addition, the coverage rate of a certain area of ​​the first light-shielding portion 21 was set to 100%. The transmittance density (OD value) of the first light-shielding portion 21 was set to 3.2.

[0091] <Comparative Example 4> As a sample for Comparative Example 4, a sample was prepared in which the inner frame shape of the first light-shielding part 21 was a rounded rectangular shape. The length of the first light-shielding part 21 in the horizontal direction X1 was 0.70 mm, and the length of the vertical direction Y1 was 0.55 mm. The area ratio of the first light-shielding part 21 on the optically effective surface 13 was 34%. In addition, the coverage rate of a certain area of ​​the first light-shielding part 21 was 100%. The transmittance density (OD value) of the first light-shielding part 21 was 3.2.

[0092] <Sample Evaluation> The samples (optical elements) prepared as described above were incorporated into the optical system of an imaging device, and the image quality when a subject was imaged using the imaging device was evaluated. The image quality was evaluated by assessing the effects of fish-scale-like patterns, cross-shaped patterns, iridescent patterns, and the four corners in the captured image. A rating of "1" was given when these effects were significant, and a rating of "5" was given when these effects were small, on a 5-point scale.

[0093] The composition and evaluation results of each sample are shown in Tables 1 to 5.

[0094] [Table 1]

[0095] [Table 2]

[0096] [Table 3]

[0097] [Table 4]

[0098] [Table 5]

[0099] Although the present invention has been described above in reference to the embodiments described above, the present invention is not limited to the configuration of the embodiments described above, and of course includes various modifications, alterations, and combinations that can be made by a person skilled in the art within the scope of the claims of the present patent application. [Explanation of Symbols]

[0100] 1, 1a, 1b Optical elements 10 Transparent base material 11 Light blocking layer 13 Optically Effective Surface 21 First light-shielding section 22 Second light-shielding section 31 First area 32 Second area 33 Third area 41, 51 Light incident surface 42, 52 light emitting surface 43, 55, 56 Optical axis

Claims

[Claim 1] Transparent substrate and An optical element comprising a light-shielding layer formed around the outer edge of the optically effective surface of the transparent substrate, The light-shielding layer comprises a first light-shielding portion provided on the outer edge side and a second light-shielding portion provided on the central side of the optically effective surface relative to the first light-shielding portion. Optical element.

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