Optical element, optical system, lens device, and image pickup device

Abstract

The invention relates to an optical element, an optical system, a lens device, and an image pickup device. The optical element includes a plurality of annular portions arranged concentrically. The plurality of annular portions includes a first annular portion including a plurality of first structures each having a first height and a plurality of second structures each having a second height, the second height being different from the first height. The plurality of first structures have different widths from each other in a radial direction. The plurality of second structures have different widths from each other in the radial direction.

Description

Technical Field

[0001] One of aspects of the embodiments relates to an optical element, an optical system, a lens device, and an image pickup device. Background Art

[0002] In order to reduce the size of the optical system in an image pickup device, etc., an optical element (metalens) having a fine concave-convex (undulation, relief or texture) structure formed on the surface of a substrate and using diffraction to provide a light converging or diverging effect is conventionally known. U.S. Patent Application Publication No. 2020 / 0174163 discloses a metalens formed by a fine concave-convex structure.

[0003] In order to increase the diffraction efficiency (the ratio of the amount of light directed toward a specific diffraction angle to the amount of incident light) in an optical element having a fine concave-convex structure, the repetition period (pitch) of the fine concave-convex structure can be smaller than the wavelength of the incident light. By changing the shape of the fine concave-convex structure for each pitch, a smooth phase distribution can be achieved.

[0004] However, as the pitch decreases, the aspect ratio of the fine concavo-convex structure increases. Therefore, it becomes difficult to form the fine concavo-convex structure and maintain its shape, and the fine concavo-convex structure may be deformed by a slight load, temperature, pressure, or the like. Summary of the invention

[0005] An optical element according to one aspect of the present disclosure includes a plurality of annular sections arranged concentrically. The plurality of annular sections include a first annular section, the first annular section including a plurality of first structures each having a first height and a plurality of second structures each having a second height, the second height being different from the first height. The plurality of first structures have mutually different widths in a radial direction. The plurality of second structures have mutually different widths in the radial direction.

[0006] Further features of various embodiments of the present disclosure will become apparent from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A , 1B and 1C are configuration diagrams of optical elements according to each example.

[0008] Figure 2 is a configuration diagram of an optical element according to a comparative example.

[0009] Figure 3 The relationship between the shape of an uneven element of the optical element and the phase modulation amount in each example is illustrated.

[0010] Figure 4 The relationship between the shape of the concavo-convex element of the optical element in the comparative example and the phase modulation amount is illustrated.

[0011] Figure 5A , 5B and 5C explain a method for manufacturing an optical element according to each example.

[0012] Figure 6 The offset layer according to each example is explained.

[0013] Figure 7 The modulation amount of the normalized phase in the radial direction of the optical element according to each example is explained.

[0014] Figure 8 The width of the concavo-convex element in the radial direction of each of the optical elements according to each of the examples and the comparative examples is explained.

[0015] Fig.9A and 9B The component filling ratio according to each example is explained.

[0016] Fig.10 is a configuration diagram of the optical element according to Example 16.

[0017] Fig.11 is a configuration diagram of the optical element according to Example 17.

[0018] Fig. 12A and 12B is a configuration diagram of the optical element according to Example 18.

[0019] Fig.13 An optical system including an optical element according to any of the above examples is explained.

[0020] Fig.14 An image pickup device having an optical element according to any of the above examples is explained. DETAILED DESCRIPTION

[0021] Referring now to the drawings, a detailed description will be given of embodiments according to the present disclosure.

[0022] Reference now Figure 1A , 1B and 1C, a description will be given of the optical element 100 according to each example. Figure 1A , 1B and 1C are configuration diagrams of the optical element 100. Figure 1A is an enlarged cross-sectional view of the optical element 100 (on the xz plane) viewed from the y-axis direction. Figure 1B1 is an enlarged top view of the optical element 100 (on the xy plane) viewed from the z-axis direction (optical axis direction). Figure 1C is an overall top view of the optical element 100 (on the xy plane) viewed from the z-axis direction (optical axis direction). In each example, the optical axis direction of the optical element 100 and the thickness direction of the substrate 1 coincide with the z-axis direction.

[0023] The optical element 100 according to each example includes a substrate 1 and a concave-convex structure (column) 2 formed on the substrate 1. The concave-convex structure 2 includes a plurality of concave-convex elements (a plurality of structures) including at least one of a concave portion or a convex portion periodically arranged in a radial direction. Forming a periodic phase difference (annular portion or ring) in the radial direction of the substrate 1 can provide a converging or diverging effect on the incident light. The optical element 100 includes a plurality of annular portions, which include a first annular portion (the i-th annular portion or ring) and a second annular portion (the (i+1)-th annular portion or ring) disposed in a radial direction so as to extend in a circumferential direction relative to the center of the optical element 100. Each of the plurality of annular portions has an area A1 (a first area) and an area A2 (a second area) disposed in a radial direction of the optical element 100. In each example, at least one of the plurality of annular portions may have areas A1 and A2, but a plurality of annular portions may have areas A1 and A2, and all annular portions may have areas A1 and A2.

[0024] A plurality of concave-convex elements (a plurality of structures) 21 has a plurality of first structures 215 disposed in an area A1 and a plurality of second structures 216 disposed in an area A2. H1 is the height (first height) of each of the plurality of first structures 215, and H2 is the height (second height) of each of the plurality of second structures 216. The heights H1 and H2 are different from each other. The heights H1 of the plurality of first structures 215 are not necessarily the same, and may be partially different from each other. This is similarly applicable to the height H2 of the plurality of second structures 216. The plurality of first structures 215 have different widths in the radial direction. Similarly, the plurality of second structures 216 have different widths in the radial direction. However, all widths of the plurality of first structures 215 do not need to be different, and some of them may be the same. This is similarly applicable to the widths of the plurality of second structures 216.

[0025] Substrate 1 is a transparent flat plate made of synthetic quartz. Substrate 1 can be a plane mirror that reflects incident light, or can be a curved surface with an arbitrary curvature. The material of substrate 1 is not limited to synthetic quartz, and can be inorganic glass, organic materials such as plastics, ceramics, metals, etc. A concave-convex structure 2 is formed on the surface of substrate 1, and provides a phase difference to the light passing through the concave-convex structure 2, thereby giving a light converging or diverging effect. Each example obtains a light converging effect almost equivalent to that of a diffractive optical element by forming a phase distribution using annular parts that are concentric and periodically repeated with a phase difference of 2nπ (n=1, 2, ..., representing an integer representing a designed diffraction order or a diffraction order).

[0026] The concave-convex structure 2 has a concave-convex element 21. The concave-convex element 21 is composed of periodically arranged concave or convex parts. In each example, the concave-convex element 21 is composed of a convex cylindrical element, which is made of a dielectric material Si3N4. The shape of the concave-convex element 21 is not limited to a convex cylindrical element, but can be a polygonal column, a polygonal cone, a cone, any concave element or a combination thereof. The material of the concave-convex element 21 can be TiO2, GaN, GaP, GaAs, Si, SiC, Al2O3, SiO2, etc.

[0027] The concave-convex element 21 is a convex cylindrical element disposed at the center of a unit segment 11 divided into squares in the radial direction of the substrate 1. Since the width (pitch) of the segment 11 is smaller than the wavelength of the incident light, the light is effectively phase modulated according to the effective refractive index required to occupy the filling rate (element filling rate) of the unit segment (segment) regardless of the shape of the concave-convex element 21. For example, in the case where the incident light is in the visible light range (400 to 700nm), the pitch (array period) P [nm] can be less than 400nm, and because unnecessary diffracted light can be suppressed, the pitch P can be further reduced. The i-th annular portion (i = 1, 2, ...) has an area A1 and an area A2, wherein the area A1 has a plurality of concave-convex elements 21 and a substrate 1 with a height of H1, and the area A2 has a plurality of concave-convex elements 21 with a height of H2.

[0028] In each example, the convex elements in the concave-convex elements 21 in the regions A1 and A2 are made of the same material of Si3N4. Each of the regions A1 and A2 in the i-th annular portion has a plurality of concave-convex elements 21, and each shape has a different width in the radial direction of the substrate 1. Thus, a phase distribution of 2mπ in the annular portion is formed. Although Figure 1B The top view of FIG. 1 is a schematic diagram illustrating a one-dimensionally arranged segment 11, but the segment 11 may be arranged two-dimensionally to obtain light converging and diverging effects. In the direction orthogonal to the optical axis, RLi and RHi are the radii of the regions A1 and A2 in the i-th annular portion from the optical axis, respectively. Figure 1CIt is understood that the regions A1 and A2 are alternately arranged concentrically in a direction orthogonal to the optical axis so that RLi <RHi。

[0029] Reference now Figure 2 , a description will be given of an optical element 101 in which the concavo-convex element 21 has a constant height H in the entire area according to a comparative example. Figure 2 1 is a configuration diagram of an optical element 101 according to a comparative example. In order to form a phase distribution of 2nπ in the annular portion, the width (diameter) of the convex cylindrical element as the concave-convex element 21 is changed, and the element filling rate of the concave-convex element 21 in the segment is changed. That is, the element filling rate decreases in sequence from the convex cylindrical element with a large diameter to the convex cylindrical element with a small diameter, and a desired phase distribution is formed. Figure 2 In the optical element 101 shown in , the element filling rate is adjusted only by the diameter of the convex cylindrical element, so the diameter is significantly changed. Therefore, the minimum diameter of the convex cylindrical element tends to decrease, and the aspect ratio (the ratio of the height to the width of the concave-convex element 21 (height / width)) tends to increase. For relatively slender elements with a large aspect ratio, the shape may be deformed, tilted, or peeled off when a load is applied due to contact or vibration, or when external factors such as temperature or pressure change. Therefore, each example forms a concave-convex structure 2 without increasing the aspect ratio by reducing the height of the concave-convex element in the area A2 where the phase modulation amount is relatively small.

[0030] Figure 3 The relationship between the shape of the concavo-convex element 21 of the optical element 100 according to each example and the phase modulation amount is illustrated, and the diameter of the convex cylindrical element as the concavo-convex element 21 and the phase modulation amount are involved. Figure 3 , the horizontal axis represents the diameter W of the convex cylindrical element (the normalized diameter normalized by the pitch P of the segment), and the vertical axis represents the normalized phase obtained by normalizing the phase modulation amount by 2mπ (where the diffraction order m is 1). When the normalized phase is in the range from 0 to 0.488, the normalized diameter of the convex cylindrical element in region A2 changes from 0.187 to 0.813. When the normalized phase is in the range from 0.488 to 1, the normalized diameter of the convex cylindrical element in region A1 changes from 0.592 to 0.813. Thus, the phase modulation amount of the normalized phase 0 to 1 can be obtained. The maximum value AR1 of the aspect ratio of the multiple structures 215 in region A1 is 6.2, and the maximum value AR2 of the aspect ratio of the multiple structures 216 in region A2 is 9.8.

[0031] Figure 4The relationship between the shape of the concave-convex element 21 of the optical element 101 according to the comparative example and the phase modulation amount is illustrated, and relates to the diameter of the convex cylindrical element and the phase modulation amount in the optical element 101. At this time, in order to obtain the phase modulation amount of the normalized phase 0 to 1, the normalized diameter is changed from 0.181 to 0.819, and the maximum value of the aspect ratio is 20.2, which is larger than the case where the height of the concave-convex element 21 is changed for each region. It is understood from this that changing the height of the concave-convex element 21 can suppress the aspect ratio of the concave-convex element 21.

[0032] Reference now Figure 5A , 5B 5C, a description will be given of a method for manufacturing the optical element 100 according to each example. The optical element 100 can be manufactured using a photolithography technique. Figure 5A , 5B 5C explain a method for manufacturing the optical element 100 and illustrate steps for manufacturing the optical element 100 using nanoimprint lithography. Figure 5A The mold 31 is shown in the figure, and the mold 31 has a shape which is the inverse of the concavo-convex shape of the concavo-convex element 21 formed by electron beam, laser, etc. Figure 5B As shown in , a resist material 32 is applied to a film 33 deposited on a substrate 1, a mold 31 is pressed, and ultraviolet rays or the like are irradiated so that a reverse shape of the concavo-convex shape of the mold 31 is formed on the resist material 32. Thereafter, as Figure 5C As shown in , the mold 31 is peeled off and developed so that the concavo-convex shape of the resist material 32 is transferred to the film 33, thereby forming the concavo-convex structure 2 on the substrate 1 of the optical element 100. In each example, the method for manufacturing the concavo-convex structure 2 is not limited to nanoimprint lithography, and another method may be used, such as directly forming the concavo-convex structure 2 using an electron beam, a laser, or the like.

[0033] Figure 6 The offset layer 34 according to each example is explained. Figure 6 As shown in Figure 5C In the structure shown in FIG. 1 , the concavo-convex structure 2 is directly formed on the substrate 1 , and an offset layer 34 disposed across the regions A1 and A2 may be provided. The substrate 1 may include the offset layer 34 , and be treated as the substrate 1 .

[0034] Now assume that H1 is the height of each of the concavo-convex elements 21 in the region A1 (the height of each of the plurality of first structures 215), and H2 is the height of each of the concavo-convex elements 21 in the region A2 (the height of each of the plurality of second structures 216). Wmax1 is the maximum width of the concavo-convex elements 21 in the region A1 (the maximum width of the plurality of first structures 215, Figure 1AWmax2 is the maximum width of the concave-convex element 21 in region A2 (the maximum width of the plurality of second structures 216, Figure 1A Wmin1 is the width of the leftmost convex element in region A2 in the region A1). Wmin1 is the minimum width of the concave-convex element 21 in region A1 (the minimum width of the plurality of first structures 215, Figure 1A Wmin2 is the minimum width of the concave-convex element 21 in region A2 (the minimum width of the plurality of second structures 216, Figure 1A = The width of the rightmost convex element in region A2 in FIG. 1 ). At this time, the following inequalities (1) to (3) can be satisfied in each example:

[0035] 0.05≤H2 / H1≤0.95 (1)

[0036] 1.00<Wmaxl / Wmin1<20.00 (2)

[0037] 1.00<Wmax2 / Wmin2<20.00 (3)

[0038] Inequality (1) relates to the shape of the concave-convex element 21. Due to the height H2 of the concave-convex element 21 in the region A2 where the phase modulation amount is relatively small (which is lower than the height H1 of the concave-convex element 21 in the region A1), a desired phase modulation amount can be obtained while realizing a shape of the concave-convex element 21 with a reduced aspect ratio.

[0039] In the case where the value becomes lower than the lower limit of the inequality (1), the height H2 of the concave-convex element 21 in the region A2 becomes relatively low, and the phase modulation amount cannot be increased when the width of the concave-convex element 21 in the region A2 is changed. At this time, in order to obtain the desired phase modulation amount, the width of the concave-convex element 21 in the region A2 will be relatively significantly changed, so that the effect of reducing the aspect ratio in the region A2 cannot be obtained. In each example, the lower limit of the inequality (1) can be changed to 0.10, 0.15, 0.20, 0.24, 0.28, 0.32, 0.34 or 0.36.

[0040] On the other hand, in the case where the value becomes higher than the upper limit of the inequality (1), the height H2 of the concave-convex element 21 in the region A2 becomes relatively high, and in order to obtain the desired phase modulation amount, the width of the concave-convex element 21 in the region A2 will be relatively reduced, and thus the effect of reducing the aspect ratio in the region A2 cannot be obtained. In each example, the upper limit of the inequality (1) can be changed to 0.90, 0.85, 0.80, 0.76, 0.72, 0.70, 0.68, 0.66, 0.64, 0.62, or 0.60.

[0041] In the case where the concavo-convex element 21 has a cylindrical shape, the diameter of the circle may be used as the width of the concavo-convex element, such as Figure 1B The width of the concave-convex element 21 may be the length of a side when the concave-convex element 21 has a quadrangular prism element, or may be the converted diameter of a cylindrical element providing an equivalent phase modulation amount when the concave-convex element 21 has a complex shape.

[0042] Inequalities (2) and (3) relate to the shape of the concavo-convex element 21. In the regions A1 and A2, changing the width of the concavo-convex element 21 within a predetermined range can provide a desired phase modulation amount.

[0043] Inequalities (2) and (3) normalize the maximum width of the concave-convex element 21 using the minimum width of the concave-convex element 21, so the value will never become lower than the lower limit of inequalities (2) and (3), but by increasing the value to a certain extent, the desired phase modulation amount can be easily obtained. In each example, the lower limit of inequalities (2) and (3) can be changed to 1.04, 1.08, 1.12, 0.14, 1.18, 1.22, 1.24 or 1.26. In the case where the value becomes higher than the upper limit of inequalities (2) and (3), the width of the concave-convex element 21 becomes relatively small and the aspect ratio increases. In each example, the upper limit of inequalities (2) and (3) can be changed to 18.00, 16.00, 14.00, 12.00, 10.00, 8.00, 7.00, 6.00 or 5.00.

[0044] In the case where the height of the concavo-convex element 21 has slight fluctuations in the radial direction of the substrate, the average value of the height of the concavo-convex element in the annular portion may satisfy inequality (1). In addition, in an area where the effect of each example is not expected (such as an unintentional local concavo-convex portion due to a manufacturing error or a structure outside the light effective portion), inequalities (1) to (3) may not be satisfied.

[0045] In each example, when each of the plurality of structures includes a concave element, each structure refers to a structure including a side surface and a bottom surface of a space forming a concave portion. In this case, the height of the structure is the height of the concave portion, and the width of the structure is the width of the concave portion.

[0046] Now assume that P is the repetition period of the concave-convex element (array period of the concave-convex element as a unit element of the plurality of structures: pitch). ΔW1 is the difference between the maximum width and the minimum width of the concave-convex element 21 in the region A1 (the difference between the maximum width and the minimum width of the plurality of first structures 215), and ΔW2 is the difference between the maximum width and the minimum width of the concave-convex element 21 in the region A2 (the difference between the maximum width and the minimum width of the plurality of second structures 216). At this time, in each example, the following inequalities (4) and (5) can be satisfied.

[0047] 0.05≤ΔW1 / P≤0.80 (4)

[0048] 0.15≤ΔW2 / P≤0.95 (5)

[0049] Inequalities (4) and (5) relate to the shape of the concave-convex element 21 in the radial direction. Satisfying inequalities (4) and (5) can suppress the amount of change in the width of the concave-convex element 21, and realize a shape in which the aspect ratio of the concave-convex element 21 is reduced. In the case where the value becomes lower than the lower limit of inequalities (4) and (5), the phase modulation amount obtained by a slight change in the width of the concave-convex element 21 changes significantly, and it becomes difficult to stably manufacture an optical element having desired performance. In the case where the value becomes higher than the upper limit of inequalities (4) and (5), the width of the concave-convex element 21 decreases, the aspect ratio increases, the distance between adjacent concave-convex elements decreases, and manufacturing becomes difficult.

[0050] In order to further ensure the effect of each example, the lower limit of inequality (4) can be changed to 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14 or 0.15. The upper limit of inequality (4) can be changed to 0.76, 0.72, 0.68, 0.64, 0.62 or 0.60. The lower limit of inequality (5) can be changed to 0.16, 0.17, 0.18, 0.20, 0.22, 0.24 or 0.26. The upper limit of inequality (5) can be changed to 0.90, 0.86, 0.82, 0.78, 0.74, 0.72 or 0.70.

[0051] In each example, the following inequality (6) can be satisfied:

[0052] 0.05≤ΔW1 / ΔW2≤1.50 (6)

[0053] Inequality (6) relates to the relationship between the shapes of the concave-convex elements 21 in regions A1 and A2. Satisfying inequality (6) can achieve a shape in which the aspect ratio of the concave-convex element in region A2 is particularly reduced. When the value becomes lower than the lower limit of inequality (6), the phase modulation amount obtained by a slight change in the width of the concave-convex element 21 in region A1 changes significantly, and it becomes difficult to stably manufacture an optical element with desired performance. On the other hand, when the value becomes higher than the upper limit of inequality (6), the width change amount of the concave-convex element 21 in region A1 becomes relatively large, and the aspect ratio increases. In order to further ensure the effect of each example, the lower limit of inequality (6) can be changed to 0.10, 0.14, 0.18, 0.22, 0.24 or 0.25. The upper limit of inequality (6) can be changed to 1.45, 1.40, 1.35, 1.30, 1.25 or 1.20.

[0054] With respect to light traveling in the thickness direction of the substrate 1 , the phase modulation amount (phase delay amount) caused by the concavo-convex structure 2 may be larger in the region A1 than in the region A2 . Figure 7 The modulation amount of the normalized phase in the radial direction of the substrate 1 is explained. Figure 7 , the vertical axis represents the normalized phase, and the horizontal axis represents the position in the radial direction. Figure 8 Explain the width of the concave and convex elements (e.g., the diameter of the convex cylindrical element, etc.). Figure 8 In FIG. 1 , the vertical axis represents the width of the concave-convex element, and the horizontal axis represents the position in the radial direction. Figure 8 , the solid line illustrates the structure of the optical element 100 according to each example, and the dotted line illustrates the structure of the optical element 101 according to the comparative example having a concavo-convex structure of a constant height.

[0055] Each example makes the height of the concavo-convex element in region A1 higher than the height of the concavo-convex element in region A2 to increase the phase modulation amount, changes the concavo-convex element width in each region so that the change amount of the concavo-convex element width is smaller than the change amount of the concavo-convex element width in the comparative example, and thereby suppresses the aspect ratio of the concavo-convex elements in regions A1 and A2. In the case where the phase modulation caused by the concavo-convex structure in region A1 is smaller than the phase modulation caused by the concavo-convex structure in region A2, unless the change amount of the concavo-convex element width in regions A1 and A2 is relatively large, the desired phase distribution cannot be obtained, and the effect of suppressing the aspect ratio cannot be obtained.

[0056] Reference now Fig.9A and 9B , a description of the component filling ratio will be given. Fig.9A and 9B Explains component fill ratio. Fig.9AThe element filling rate in the area A1 where the concavo-convex elements 21 having a height H1 are disposed is shown, and Fig. 9B The element filling rate in the area A2 where the concavo-convex elements 21 having a height H2 are disposed is illustrated.

[0057] The element filling rate is the ratio of the volume occupied by the concave and convex elements in each segment. Fig.9A and 9B As shown in , the element filling rate in regions A1 and A2 is the volume ratio of the concave-convex element 21 to the volume Va defined by the bottom surface P×P multiplied by the height H1. Assume that V1min is the minimum value of the element filling rate of the concave-convex element in region A1, and V2max is the maximum value of the element filling rate of the concave-convex element in region A2, relative to the repetition period P and the height H1 of the concave-convex element in region A1. Then, the following inequality (7) can be satisfied:

[0058] 0.70≤V2max / V1min≤1.50 (7)

[0059] Inequality (7) relates to the shape of the concave-convex elements in regions A1 and A2. Satisfying inequality (7) can achieve a shape in which the aspect ratio of the concave-convex element is reduced. When the value becomes lower than the lower limit of inequality (7), the minimum width of the concave-convex structure in region A1 decreases and the aspect ratio increases. On the other hand, when the value becomes higher than the upper limit of inequality (7), the maximum width of the concave-convex structure in region A2 increases, the distance between the concave-convex elements decreases, and manufacturing becomes difficult. In order to further ensure the effect of each example, the lower limit of inequality (7) can be changed to 0.74, 0.76, 0.78, 0.79, 0.80, 0.81 or 0.82. The upper limit of inequality (7) can be changed to 1.45, 1.40, 1.35, 1.30, 1.25 or 1.20.

[0060] The following inequalities (8) to (10) can be satisfied:

[0061] 1.50≤AR1≤20.00 (S)

[0062] 1.50≤AR2≤20.00 (9)

[0063] 0.50≤AR2 / AR1≤4.00 (10)

[0064] Wherein AR1 is the maximum value of the aspect ratio of the concavo-convex elements in the region A1, and AR2 is the maximum value of the aspect ratio of the concavo-convex elements in the region A2.

[0065] Inequalities (8) and (9) relate to the shape of the concave-convex elements in regions A1 and A2. When the value becomes lower than the lower limit of inequalities (8) and (9), the phase modulation becomes relatively large due to the slight change in the width of the concave-convex element, the influence of manufacturing variations when forming the concave-convex structure increases, and manufacturing becomes difficult. On the other hand, when the value becomes higher than the upper limit of inequalities (8) and (9), the aspect ratio increases and the structure is likely to collapse due to external factors. In order to further ensure the effect of each example, the lower limit of inequalities (8) and (9) can be changed to 2.00, 3.00, 3.40, 3.80, 4.00, 4.20, 4.40, 4.60, 4.80, 5.00 or 5.20. The upper limits of inequalities (8) and (9) may be changed to 18.00, 16.00, 15.00, 14.00, 13.00, 12.00, 11.00, 10.00, 9.00, or 8.00.

[0066] Inequality (10) relates to the shape of the concave-convex element. When the value becomes lower than the lower limit of inequality (10), the change in the width of the concave-convex element in region A1 becomes larger, and the effect of suppressing the aspect ratio in region A1 cannot be obtained. When the value becomes higher than the upper limit of inequality (10), the change in the width of the concave-convex element in region A2 increases, and the effect of suppressing the aspect ratio in region A2 cannot be obtained. In order to further ensure the effect of each example, the lower limit of inequality (10) can be changed to 0.60, 0.80, 1.00, 1.20, 1.40, 1.60, 1.80, 1.90 or 2.00. The upper limit of inequality (10) can be changed to 3.80, 3.60, 3.40, 3.20, 3.00, 2.80, 2.60, 2.50 or 2.40.

[0067] In each example, the maximum widths Wmax1 to Wmax2 of the concavo-convex elements in the regions A1 and A2 may satisfy the following inequality (11):

[0068] 0.60≤Wmax2 / Wmaxl≤1.20 (11)

[0069] Inequality (11) is related to the shape of the concave-convex element. When the value becomes lower than the lower limit of inequality (11), the concave-convex element width in region A2 becomes relatively small, and the aspect ratio will increase in order to obtain the desired phase difference. On the other hand, when the value becomes higher than the upper limit of inequality (11), the concave-convex element width in region A1 becomes relatively small, and the aspect ratio will increase in order to obtain the desired phase difference. In order to further ensure the effect of each example, the lower limit of inequality (11) can be changed to 0.60, 0.65, 0.70, 0.75, 0.80, 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, 0.94 or 0.95. The upper limit of inequality (11) can be changed to 1.18, 1.16, 1.14, 1.12, 1.10, 1.08, 1.06 or 1.05.

[0070] In the optical element according to each example, the phase distribution depends on the reference wavelength λ0. The following inequality (12) can be satisfied:

[0071] 0.25≤ΔH / m / λ0≤3.00 (12)

[0072] where ΔH is the difference in height between relief elements in areas A1 and A2, and m is the diffraction order.

[0073] Inequality (12) relates to the shape of the concave-convex element. The phase distribution determines the annular portion based on the phase relative to the reference wavelength λ0. When the value becomes lower than the lower limit of inequality (12), the difference in the phase modulation amount obtained in regions A1 and A2 decreases, so unless the change in the width of the concave-convex element in each region increases, it is difficult to obtain the desired phase difference, and therefore the effect of suppressing the aspect ratio cannot be obtained. On the other hand, when the value becomes higher than the upper limit of inequality (12), the aspect ratio increases and the structure is prone to collapse due to external factors. In order to further ensure the effect of each example, the lower limit of inequality (12) can be changed to 0.30, 0.35, 0.40, 0.45, 0.50, 0.60, 0.65, 0.70 or 0.75. The upper limit of inequality (12) can be changed to 2.50, 2.00, 1.80, 1.60, 1.40, 1.30 or 1.20.

[0074] In each example, the following inequalities (13) and (14) can be satisfied:

[0075] 0.15≤NP≤0.85 (13)

[0076] 0.50≤NP / H2×H1≤1.500 (14)

[0077] Where NP is the ratio of the minimum phase in area A1 to the maximum phase difference in the annular portion.

[0078] Inequality (13) relates to the phase modulation amount at the boundary between regions A1 and A2. When the value becomes lower than the lower limit of inequality (13), the change in the width of the concave-convex element in region A1 increases, and the effect of suppressing the aspect ratio in region A1 cannot be obtained. On the other hand, when the value becomes higher than the upper limit of inequality (13), the change in the width of the concave-convex element in region A2 increases, and the effect of suppressing the aspect ratio in region A2 cannot be obtained. In order to further ensure the effect of each example, the lower limit of inequality (13) can be changed to 0.18, 0.20, 0.22, 0.24, 0.28, 0.32, 0.34, 0.36, 0.38 or 0.40. The upper limit of inequality (13) can be changed to 0.80, 0.75, 0.70, 0.65 or 0.60.

[0079] Inequality (14) relates to the phase modulation amount at the boundary between regions A1 and A2 and the shape of the concave-convex element. By setting the ratio NP of the minimum phase in region A1 to the maximum phase difference in the annular portion according to the height of the concave-convex elements in regions A1 and A2, the effect of suppressing the aspect ratio of the concave-convex element can be more effectively obtained. In the case where the value becomes lower than the lower limit of inequality (14), the amount of change in the width of the concave-convex element in region A1 increases, and the effect of suppressing the aspect ratio in region A1 cannot be obtained. On the other hand, in the case where the value becomes higher than the upper limit of inequality (14), the amount of change in the width of the concave-convex element in region A2 increases, and the effect of suppressing the aspect ratio in region A2 cannot be obtained. In order to further ensure the effect of each example, the lower limit of inequality (14) can be changed to 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85 or 0.90. The upper limit of inequality (14) may be changed to 1.45, 1.40, 1.35, 1.30, 1.25, 1.20, 1.15, or 1.10.

[0080] The phase modulation of the concave-convex element in areas A1 and A2 can be monotonically increased or decreased in the radial direction of the substrate within the annular portion. In the case where the phase modulation increases or decreases discretely, the width of the concave-convex element will change relatively significantly, and the effect of suppressing the aspect ratio cannot be obtained. In order to present a light converging effect when a plane wave enters the optical element according to each example in the thickness direction of the substrate, the phase modulation within the annular portion shows that the phase delay decreases monotonically in the radial direction from the inside of the substrate to the periphery. In addition, in the case where the optical element 100 according to each example has a light diverging effect, the phase modulation within the annular portion shows that the phase delay increases monotonically in the radial direction from the inside of the substrate to the periphery.

[0081] In each example, the following inequality (15) can be satisfied:

[0082] 0.00≤112 / t≤0.10(15)

[0083] Wherein t is the thickness of the substrate 1 in the direction of the optical axis.

[0084] Inequality (15) relates to the shape of the optical element. The height H2 of the concave-convex element in region A2 and the thickness t of the substrate are both numerical values ​​indicating length, and are greater than 0. Therefore, the value will never become lower than the lower limit of inequality (15). In the case where the value becomes higher than the upper limit of inequality (15), the substrate becomes relatively thin, and the deformation caused by its own weight cannot be suppressed when the substrate is held by a holder, or the substrate may be deformed during manufacture using photolithography. In order to further ensure the effect of each example, the lower limit of inequality (15) can be changed to 0.000001, 0.000005, 0.00001 or 0.0001. The upper limit of inequality (15) can be changed to 0.08, 0.06, 0.04, 0.02, 0.01, 0.008, 0.006 or 0.004.

[0085] A detailed description will now be given of the optical element according to each example.

[0086] The optical element according to Example 1 has a concavo-convex structure including a substrate made of synthetic quartz and having a thickness of 0.775 mm, and convex cylindrical elements made of Si3N4. The concavo-convex elements in the regions A1 and A2 are arranged for each square segment having a side length of 240 nm, and have heights H1 and H2 of 880 nm and 440 nm, respectively. The concavo-convex structure has The effective diameter of the optical element is 105 annular sections that are periodically repeated at a wavelength of 500 nm with a phase difference of 2π (diffraction order is 1), and a focal length of 40.0 mm. The position where the normalized phase is 0.488 is set as the boundary between regions A1 and A2 in the annular section, and the maximum values ​​of the aspect ratios in regions A1 and A2 are 6.20 and 9.80, respectively. Therefore, compared with the maximum aspect ratio of 20.2 in reference example 1 in which the height of the concave-convex elements is equal in all regions, the aspect ratio can be suppressed.

[0087] The optical element according to Example 2 has a concavo-convex structure including a substrate made of synthetic quartz and having a thickness of 0.775 mm, and convex cylindrical elements made of Si3N4. The concavo-convex elements in the regions A1 and A2 are arranged for each square segment having a side length of 300 nm, and have heights H1 and H2 of 1000 nm and 500 nm, respectively. The concavo-convex structure has The effective diameter of the optical waveguide 2 is 67 annular sections that are periodically repeated at a wavelength of 587.56 nm with a phase difference of 2π (diffraction order is 1), and a focal length of 20.0 mm. The position where the normalized phase is 0.510 is set as the boundary between regions A1 and A2 in the annular section, and the maximum values ​​of the aspect ratios in regions A1 and A2 are 5.55 and 9.18, respectively. Therefore, compared with the maximum aspect ratio of 18.9 in Reference Example 2 in which the height of the concave-convex elements is equal in all regions, the aspect ratio can be suppressed.

[0088] The optical element according to Example 3 has a concavo-convex structure including a substrate made of synthetic quartz and having a thickness of 0.775 mm, and convex cylindrical elements made of Si3N4. The concavo-convex elements in the regions A1 and A2 are arranged for each square segment having a side length of 320 nm, and have heights H1 and H2 of 1600 nm and 800 nm, respectively. The concavo-convex structure has The effective diameter of the optical element is 72 annular sections that are periodically repeated at a wavelength of 546.07 nm with a phase difference of 4π (diffraction order is 2), and a focal length of 10.0 mm. The position where the normalized phase is 0.498 is set as the boundary between regions A1 and A2 in the annular section, and the maximum values ​​of the aspect ratios in regions A1 and A2 are 8.57 and 15.06, respectively. Therefore, compared with the maximum aspect ratio of 31.3 in reference example 3 in which the height of the concave-convex elements is equal in all regions, the aspect ratio can be suppressed.

[0089] The optical element according to Example 4 has a concavo-convex structure including a substrate made of synthetic quartz and having a thickness of 0.775 mm, a convex cylindrical element made of TiO2, and an offset layer having a uniform thickness. The concavo-convex elements in the regions A1 and A2 are arranged for each square segment having a side length of 240 nm and have heights H1 and H2 of 600 nm and 300 nm, respectively. The concavo-convex structure has The effective diameter of the optical waveguide 2 is 90 annular sections that are periodically repeated at a wavelength of 500 nm with a phase difference of 2π (diffraction order is 1), and a focal length of 100.0 mm. The position where the normalized phase is 0.475 is set as the boundary between regions A1 and A2 in the annular section, and the maximum values ​​of the aspect ratios in regions A1 and A2 are 4.25 and 5.83, respectively. Therefore, compared with the maximum aspect ratio of 11.9 in reference example 4 in which the height of the concave-convex elements is equal in all regions, the aspect ratio can be suppressed.

[0090] The optical element according to Example 5 has a concavo-convex structure including a substrate made of synthetic quartz and having a thickness of 2.0 mm, a convex cylindrical element made of Al2O3, and an offset layer having a uniform thickness. The concavo-convex elements in the regions A1 and A2 are arranged for each square segment having a side length of 300 nm and have heights H1 and H2 of 1400 nm and 700 nm, respectively. The concavo-convex structure has The effective diameter of the optical element is 223 annular sections that are periodically repeated at a wavelength of 486.1 nm with a phase difference of 2π (diffraction order is 1), and a focal length of 41.7 mm. The position where the normalized phase is 0.490 is set as the boundary between regions A1 and A2 in the annular section, and the maximum values ​​of the aspect ratios in regions A1 and A2 are 8.08 and 12.74, respectively. Therefore, compared with the maximum aspect ratio of 26.5 in reference example 5 in which the height of the concave-convex elements is equal in all regions, the aspect ratio can be suppressed.

[0091] The optical elements according to Examples 6 to 10 respectively have specifications similar to those of the optical elements according to Examples 1 to 5, except that the heights of the concavo-convex elements in the region A2 are different.

[0092] The height of the concavoconvex elements in region A2 of the optical element according to Example 6 was 352 nm. The position where the normalized phase was 0.390 was set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 were 6.77 and 7.78, respectively.

[0093] The height of the concavoconvex elements in region A2 of the optical element according to Example 7 was 400 nm. The position where the normalized phase was 0.250 was set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 were 7.30 and 7.29, respectively.

[0094] The height of the concavoconvex elements in region A2 of the optical element according to Example 8 was 640 nm. The position where the normalized phase was 0.375 was set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 were 9.56 and 11.84, respectively.

[0095] The height of the concavoconvex elements in region A2 of the optical element according to Example 9 was 240 nm. The position where the normalized phase was 0.68 was set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 were 4.67 and 4.64, respectively.

[0096] The height of the concavoconvex elements in region A2 of the optical element according to Example 10 was 560 nm. The position where the normalized phase was 0.389 was set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 were 8.94 and 10.10, respectively.

[0097] The optical elements according to Examples 11 to 15 have specifications similar to those of the optical elements according to Examples 1 to 5, except that the height H2 of the concavo-convex elements in the area A2 is different.

[0098] The height H2 of the concavoconvex elements in region A2 of the optical element according to Example 11 is 528 nm. The position where the normalized phase is 0.590 is set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 are 5.73 and 11.83, respectively.

[0099] The height H2 of the concavoconvex element in region A2 of the optical element according to Example 12 was 600 nm. The position where the normalized phase was 0.60 was set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 were 5.22 and 11.08, respectively.

[0100] The height H2 of the concavoconvex elements in region A2 of the optical element according to Example 13 is 960 nm. The position where the normalized phase is 0.587 is set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 are 8.00 and 18.27, respectively.

[0101] The height H2 of the concavoconvex elements in region A2 of the optical element according to Example 14 is 360 nm. The position where the normalized phase is 0.56 is set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 are 4.00 and 7.04, respectively.

[0102] The height H2 of the concavoconvex element in region A2 of the optical element according to Example 15 is 840 nm. The position where the normalized phase is 0.591 is set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 are 7.42 and 15.41, respectively.

[0103] The optical element according to Example 16 has specifications similar to those of the optical element according to Example 1, except that the height H1 of the concavo-convex elements in the area A1 is different.

[0104] Fig.10 is a configuration diagram of the optical element according to Example 16. Fig.10As shown in , region A2 of the optical element according to Example 16 has region A21 in which the height of the concave-convex elements is H21 and region A22 in which the height of the concave-convex elements is H22. The height of the concave-convex elements in region A1 is 880nm, and the heights of the concave-convex elements in region A2 are 528nm and 352nm, respectively. The position where the concave-convex elements in region A2 in the annular portion have different heights is the position where the normalized phase is 0.28, and the boundary between regions A1 and A2 is the position where the normalized phase is 0.59. The maximum value of the aspect ratio in region A1 is 5.74, and the maximum values ​​of the aspect ratio in region A2 are 3.74 and 7.07.

[0105] The optical element according to Example 17 has a concavo-convex structure including a substrate made of synthetic quartz and convex quadrangular prism elements made of Si 3 N 4 .

[0106] Fig.11 : is a configuration diagram (top view) of an optical element according to Example 17. The quadrangular prism elements in regions A1 and A2 are arranged for each square segment having a side length of 240 nm, and have heights H1 and H2 of 800 nm and 400 nm, respectively. The concavo-convex structure has an effective diameter and number of annular portions similar to those of the optical element according to Example 1. The width of the concavo-convex elements in the quadrangular prism elements can be calculated using Fig.11 The length of the side of the quadrangular prism in the radial direction of the optical element shown in . The position where the normalized phase is 0.478 is set as the boundary between the regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratio in the regions A1 and A2 are 6.09 and 7.26, respectively. Therefore, the aspect ratio can be suppressed compared to the maximum aspect ratio of 15.3 in Reference Example 6 in which the height of the concave-convex elements is equal in all regions.

[0107] The optical element according to Example 18 has a concavo-convex structure including a substrate made of synthetic quartz and a concave cylindrical element made of Si3N4. Fig. 12A and 12B is a configuration diagram of the optical element according to Example 18. Fig. 12A is a cross-sectional view, and Fig. 12BIt is a top view. The quadrangular prism elements in regions A1 and A2 are arranged for each square segment with a side length of 240nm, and have heights of 800nm ​​and 560nm, respectively. The concave-convex structure has an effective diameter and number of annular portions, which are similar to the effective diameter and number of annular portions of the optical element according to Example 1. The minimum width of the concave-convex element in the concave-convex element can use the value obtained by subtracting the maximum width of the concave element from the repetition period P. That is, the minimum widths of the concave-convex elements in regions A1 and A2 in Example 18 are 60.9nm and 42.8nm, respectively. The position where the normalized phase is 0.478 is set as the boundary between regions A1 and A2 in the annular portion, and the maximum values ​​of the aspect ratios in regions A1 and A2 are 13.13 and 13.09, respectively. Therefore, compared with the maximum aspect ratio of 37.9 in reference example 7 where the height of the concave-convex elements is equal in all regions, the aspect ratio can be suppressed.

[0108] Numerical Examples 1 to 18 corresponding to the optical elements according to Examples 1 to 18 will be illustrated below. Phase indicating the light converging and diverging effects of the concavo-convex structure is expressed as follows:

[0109]

[0110] Wherein h is the height from the optical axis in a direction orthogonal to the optical axis (radial direction), m is the diffraction order of the diffracted light, λ0 is the reference wavelength, and Ck (k=1, 2, 3, . . . ) is the phase coefficient of each order.

[0111] nd, ng, nC, nF and n500 are refractive indices for d line (587.6 nm), g line (435.8 nm), F line (486.1 nm) and C line (656.3 nm) and a wavelength of 500 nm. W1 [nm] and W2 [nm] are the widths of the concave-convex elements in regions A1 and A2, respectively, and Wref [nm] is the width of the concave-convex element in the comparative example.

[0112] Numerical Example 1

[0113]

[0114] Numerical Example 2

[0115]

[0116]

[0117] Numerical Example 3

[0118]

[0119] Numerical Example 4

[0120]

[0121]

[0122] Numerical Example 5

[0123]

[0124] Numerical Example 6

[0125]

[0126]

[0127] Numerical Example 7

[0128]

[0129] Numerical Example 8

[0130]

[0131]

[0132] Numerical Example 9

[0133]

[0134]

[0135] Numerical Example 10

[0136]

[0137] Numerical Example 1l

[0138]

[0139]

[0140] Numerical Example 12

[0141]

[0142] Numerical Example 13

[0143]

[0144]

[0145] Numerical Example 14

[0146]

[0147] Numerical Example 15

[0148]

[0149]

[0150] Numerical Example 16

[0151]

[0152] Numerical Example 17

[0153]

[0154] Numerical Example 18

[0155]

[0156]

[0157] Tables 1 to 3C summarize various numerical values ​​according to each example.

[0158] Table 1

[0159] <![CDATA[Si3N4]]> <![CDATA[TiO2]]> <![CDATA[Al2O3]]> Synthetic Quartz ng 2.08394 2.48181 1.63759 1.46240 nF 2.06710 2.42034 1.63053 1.45876 nd 2.04580 2.35281 1.62153 1.45345 nC 2.03665 2.32645 1.61759 1.45084 n500 2.06337 2.40780 1.62896 1.45790

[0160] Table 2

[0161]

[0162] Table 3A

[0163]

[0164]

[0165] Table 3B

[0166]

[0167]

[0168] Table 3C

[0169]

[0170]

[0171] Table 4 illustrates numerical values ​​representing the concavo-convex structures according to comparative examples (reference examples 1 to 7) corresponding to the optical element according to each example.

[0172] Table 4

[0173]

[0174] Optical system

[0175] Reference now Fig.13 , a description will be given of an optical system including an optical element according to any of the above examples. Fig.13 An optical system including an optical element according to any of the above examples is explained. Fig.13 , reference numeral 100 denotes an optical element according to any one of the above examples, reference numeral 102 denotes a lens element, OA denotes an optical axis, IP denotes an image plane, and reference numeral 3 denotes an optical system including the optical element according to any one of the above examples. The lens element includes a lens, a diffractive optical element, a reflector, etc., and the number of the lens elements is not limited. The optical element 100 and the lens element 102 are arranged along the optical axis OA to image the incident light onto the image plane IP. The concave-convex element disposed on the surface of the image side of the optical element 100 can provide a light converging or diverging effect.

[0176] Image pickup device

[0177] Reference now Fig.14 , a description will now be given of a digital still camera (image pickup device) using an optical system including an optical element according to any of the above examples as an imaging optical system. Fig.14 An image pickup device 6 having an optical system including an optical element according to any of the above examples is explained. Fig.14 , reference numeral 4 denotes a camera body, and reference numeral 3 denotes an optical system including an optical element according to any one of the above examples. Reference numeral 5 denotes an image sensor (photoelectric conversion element) built into the camera body 4, which receives an optical image formed by the optical system 3 and performs photoelectric conversion on it, such as a CCD sensor or a CMOS sensor. The camera body 4 may be a so-called single-lens reflex camera with a quick return mirror, or a so-called mirrorless camera without a quick return mirror. Applying an optical system including an optical element according to each example to an image pickup device such as a digital still camera in this way can provide an image pickup device with a small lens.

[0178] Therefore, an optical element according to one aspect of the example includes a plurality of annular portions arranged concentrically. The plurality of annular portions include a first annular portion, the first annular portion including a plurality of first structures each having a first height and a plurality of second structures each having a second height. The plurality of first structures have mutually different widths in the radial direction. The plurality of second structures have mutually different widths in the radial direction. The following inequality is satisfied:

[0179] 0.05H2 / H1≤0.95

[0180] Wherein H1 is a first height, and H2 is a second height. Thus, each example can provide an optical element, an optical system, a lens device, and an image pickup device, each of which has a highly stable fine concavo-convex structure.

[0181] Although the disclosure has described example embodiments, it is to be understood that some embodiments are not limited to the disclosed embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An optical element comprising a plurality of concentrically arranged annular portions, It is characterized in that The plurality of annular portions include a first annular portion including a plurality of first structures each having a first height and a plurality of second structures each having a second height, the second height being different from the first height, wherein the plurality of first structures have mutually different widths in the radial direction, and The plurality of second structures have mutually different widths in the radial direction.

2. The optical element according to claim 1, characterized in that The following inequalities are satisfied: 0.05≤H2 / H1≤0.95 Wherein H1 is the first height, and H2 is the second height.

3. The optical element according to claim 1, characterized in that The following inequalities are satisfied: 1.04<Wmx1 / Wmin1<20.00 1.04<Wmax2 / Wmin2<20.00 Wherein Wmax1 is the maximum width of the plurality of first structures, Wmax2 is the maximum width of the plurality of second structures, Wmin1 is the minimum width of the plurality of first structures, and Wmin2 is the minimum width of the plurality of second structures.

4. The optical element according to claim 1, characterized in that The plurality of first structures and the plurality of second structures are arranged at the same period in the radial direction.

5. The optical element according to claim 4, characterized in that The following inequalities are satisfied: 0.05≤ΔW1 / P≤0.80 0.15≤ΔW2 / P≤0.95 Wherein P is the period, ΔW1 is the difference between the maximum width and the minimum width of the plurality of first structures, and ΔW2 is the difference between the maximum width and the minimum width of the plurality of second structures.

6. The optical element according to claim 1, characterized in that The following inequalities are satisfied: 0.05≤ΔW1 / ΔW≤1.50 Wherein ΔW1 is the difference between the maximum width and the minimum width of the plurality of first structures, and ΔW2 is the difference between the maximum width and the minimum width of the plurality of second structures.

7. The optical element according to claim 4, characterized in that The following inequalities are satisfied: 0.70≤V2max / V1min≤1.50 Wherein V1min is the minimum value of the filling rate of the plurality of first structures, and V2max is the maximum value of the filling rate of the plurality of second structures.

8. The optical element according to claim 1, characterized in that The following inequalities are satisfied: 1.50≤AR1≤20.00 1.50≤AR2≤20.00 Wherein AR1 is the maximum value of the aspect ratios of the plurality of first structures, and AR2 is the maximum value of the aspect ratios of the plurality of second structures.

9. The optical element according to claim 1, characterized in that The following inequalities are satisfied: 0.5≤AR2 / AR1≤4.00 Wherein AR1 is the maximum value of the aspect ratios of the plurality of first structures, and AR2 is the maximum value of the aspect ratios of the plurality of second structures.

10. The optical element according to claim 1, characterized in that The following inequalities are satisfied: 0.60≤Wmax2 / Wmax1≤1.20 Wherein Wmax1 is the maximum width of the plurality of first structures, and Wmax2 is the maximum width of the plurality of second structures.

11. The optical element according to claim 1, characterized in that The following inequalities are satisfied: 0.25≤ΔH / (m×λ0)≤3.00 Wherein ΔH is the difference between the first height and the second height, m ​​is the designed diffraction order, and λ0 is the designed wavelength.

12. The optical element according to claim 1, characterized in that The following inequalities are satisfied: 0.15≤NP≤0.85 Wherein NP is a value of a ratio of a minimum phase in a first region provided with the plurality of first structures to a maximum phase difference in the first annular portion.

13. The optical element according to claim 1, characterized in that The following inequalities are satisfied: 0.50≤NP / H2×H1≤1.50 Wherein NP is a value of a ratio of a minimum phase in a first region provided with the plurality of first structures to a maximum phase difference in the first annular portion, H1 is the first height, and H2 is the second height.

14. The optical element according to claim 1, characterized in that The phase modulation amount caused by each of the plurality of first structures and the plurality of second structures changes monotonically in the radial direction of the optical element.

15. The optical element according to claim 1, characterized in that The phase modulation amount caused by the plurality of first structures is greater than the phase modulation amount caused by the plurality of second structures.

16. The optical element according to claim 1, further comprising a substrate, the plurality of annular portions being arranged on the substrate, It is characterized in that The following inequalities are satisfied: 0.0≤H2 / t≤0.1 Wherein t is the thickness of the substrate, and H2 is the second height.

17. An optical system comprising a plurality of optical elements, the plurality of optical elements comprising the optical element according to any one of claims 1 to 16.

18. A lens device, comprising: The optical system according to claim 17; as well as A holder is configured to hold the optical system.

19. An image pickup device, comprising: The optical system according to claim 17; as well as An image sensor is configured to receive an image formed by the optical system.

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