WO2024106359A1

WO2024106359A1 - Optical system device, and optical element

Info

Publication number: WO2024106359A1
Application number: PCT/JP2023/040683
Authority: WO
Inventors: 縄田晃史; 田中覚
Original assignee: Ｓｃｉｖａｘ株式会社
Priority date: 2022-11-15
Filing date: 2023-11-13
Publication date: 2024-05-23

Abstract

The objective of the present invention is to provide an optical system device and an optical element capable of emitting high-contrast light even when emitting a non-circular dot pattern.　The optical system device is provided with an optical element 1 having a first lens layer including line-shaped first lenses 11 that transmit light with a wavelength λ and that are arranged periodically, and a second lens layer including line-shaped second lenses 12 that are arranged in a direction perpendicular to the first lenses 11, transmit light having a wavelength λ, and are arranged periodically, and an emitting portion 2 including light sources 7 that emit light having a wavelength λ onto a plurality of the first lenses 11 and the second lenses 12, wherein a distance L1 between the emitting portion 2 and a first focal point plane 111 of the first lenses 11 and a distance L2 between the emitting portion 2 and a second focal point plane 121 of the second lenses 12 satisfy formula 1 and formula 2, where m and n are natural numbers at least equal to 1, f1 is a focal distance of the first lenses 11, f2 is a focal distance of the second lenses 12, P1 is the magnitude of a pitch of the first lenses 11, and P2 is the magnitude of a pitch of the second lenses 12.

Description

Optical system device and optical element

The present invention relates to an optical system device and an optical element.

Three-dimensional measurement sensors using the time-of-flight (TOF) method are being adopted for mobile devices, cars, robots, and more. This measures the distance to an object from the time it takes for light irradiated from a light source to be reflected and returned. If the light from the light source is irradiated evenly onto a specified area of the object, the distance at each irradiated point can be measured, and the three-dimensional structure of the object can be detected.

The above sensor system consists of a light irradiation unit that irradiates light onto the target object, a camera unit that detects the light reflected from each point on the target object, and a calculation unit that calculates the distance to the target object from the signal received by the camera.

The camera section and calculation section can use existing CMOS imagers and CPUs, so the unique part of the above system is the light irradiation section, which consists of a laser and an optical filter. In particular, the diffusion filter, which shapes the beam by passing the laser light through a microlens array and uniformly irradiates the target object over a controlled area, is a distinctive component of the above system.

However, conventional diffusion filters have a problem in that the microlens array has a periodic structure, which causes unevenness in the light intensity due to the effects of diffraction. In order to suppress this unevenness, various measures have been taken, such as randomly arranging the lenses (for example, Patent Document 1).

On the other hand, there is a need for long-distance measurements with TOF, and the intensity of the irradiated light must be strong enough to enable such measurements. However, randomly arranged microlens arrays have a high uniformity in the irradiated light, but the intensity is low, making them unsuitable for long-distance measurements.

As a result, research is being conducted into shining a dot pattern onto the device and performing three-dimensional measurements from the time-of-flight of this light, as a way to save power while still being able to process strong light signals.

Conventionally, optical devices utilizing the Lau effect have been known to convert incident light into a dot pattern (for example, Non-Patent Document 1). This is composed of a diffraction grating with a predetermined pitch P and a light source, and is arranged so that the distance _L0 between the diffraction grating and the light source satisfies the following formula A, where λ is the wavelength of the light from the light source and n is a natural number of 1 or more.
Also, a device in which the diffraction grating is replaced with a microlens is under consideration (for example, Patent Document 2).

Special Publication 2006-500621 International Publication No. 2017/131585

As a result of intensive research by the present inventors, it has been found that when the diffraction grating is replaced with a microlens, the distance L between the focal plane of the microlens and the light source is not L ₀ but is expressed by the following formula B
It has been found that when the above condition is met, the light is further strengthened (for example, Patent Application No. 2021-137560).

In this optical system device, if you want the dot pattern to be circular, you use a spherical lens, and if you want it to be non-circular, you use an aspherical lens.

However, it was found that in this optical system device, when aspherical lenses are used as optical elements, contrast is reduced compared to when spherical lenses are used. This is because in the case of aspherical lenses, the cross-sectional shape of the lens differs depending on the direction, and the focal length differs depending on the cross-sectional shape in each direction, resulting in a discrepancy between the apparent focal length at which light is most concentrated by the aspherical lens and the actual focal length.

A simulation was performed on this matter using optical simulation software BeamPROP (manufactured by Synopsys). The irradiating part was a single light source 7 that irradiates light with a wavelength of 940 nm (λ=0.94) and a light distribution as shown in FIG. 1. As shown in FIGS. 2(a) and (b), the optical element 8 used was an aspheric lens 81 with a refractive index of 1.53 periodically arranged in a square with a pitch P of 32 μm (P=32). As shown in FIG. 2(c), the aspheric lens 81 used was a square with a side length of 32 μm in the planar shape of the XY plane and a height of 21.2 μm. The focal length of the aspheric lens 81 was 50 μm, but the focal length f ₁ of the cross-sectional shape of the aspheric lens 81 in the XZ plane was 10 μm, and the focal length f ₂ of the cross-sectional shape in the YZ plane was 80 μm. The distance L _δ between the optical element and the light source 7 was set to the following formula C (n=2). Specifically, the distance between the optical element 8 and the light source 7 was set to 1089+δ μm.

Figure 3 shows the results of a simulation of the contrast ratio when the light from the light source is irradiated onto an optical element with δ changed from 10 to 90 μm in 10 μm increments. Figure 4 shows projection diagrams from a simulation when the light from the light source is irradiated onto an optical element with (a) δ = 10 μm, (b) δ = 50 μm, and (c) δ = 80 μm.

As shown in FIG. 4(a), when δ=10 μm, the distance L between the focal plane of the cross-sectional shape of the aspheric lens in the XZ plane and the light source satisfies formula B, but the distance L between the focal plane of the cross-sectional shape of the aspheric lens in the YZ plane and the light source does not satisfy formula B, so the dots are elongated in the y direction. Also, as shown in FIG. 4(c), when δ=80 μm, the distance L between the focal plane of the cross-sectional shape of the aspheric lens in the YZ plane and the light source satisfies formula B, but the distance L between the focal plane of the cross-sectional shape of the aspheric lens in the XZ plane and the light source does not satisfy formula B, so the dots are elongated in the x direction. Also, as shown in FIG. 4(b), when δ=50 μm, the dots are circular, but neither the distance L between the focal plane of the cross-sectional shape of the aspheric lens in the XZ plane and the light source nor the distance L between the focal plane of the cross-sectional shape of the aspheric lens in the YZ plane and the light source satisfies formula B, so the contrast is lower than when δ=10 μm or δ=80 μm, as shown in FIG. 3.

As such, conventional optical systems do not take into account the difference in focal length caused by different orientations of aspherical lenses.

The present invention aims to provide an optical system device and optical element that can emit high-contrast light even when emitting a non-circular dot pattern.

In order to achieve the above object, an optical system device of the present invention includes an optical element having a first lens layer having linear first lenses that transmit light of wavelength λ and are periodically arranged, and a second lens layer having linear second lenses that transmit light of wavelength λ and are periodically arranged, arranged in a direction perpendicular to the first lenses, and an irradiation unit having a light source that irradiates a plurality of the first lenses and second lenses with light of wavelength λ, wherein m and n are natural numbers of 1 or more, a focal length of the first lens is f ₁ , a focal length of the second lens is f ₂ , a magnitude of the pitch of the first lenses is P ₁ , and a magnitude of the pitch of the second lenses is P ₂ , and a distance L ₁ between the irradiation unit and a first focal plane of the first lens and a distance L ₂ between the irradiation unit and a second focal plane of the second lens are expressed by the following formulas 1 and 2:

The present invention is characterized in that:

In this case, it is preferable that the distance between the first focal plane and the second focal plane of the optical element is within 10 μm, and it is even more preferable that the first focal plane and the second focal plane are in the same position.

In addition, in the optical element, it is preferable that the pitch _P1 of the first lens and _the pitch _P2 of the second lens satisfy _mP12 ⁼ ^nP22 .

The optical element may also include an intermediate layer between the first lens layer and the second lens layer, the intermediate layer having a lower refractive index than the materials of the first lens layer and the second lens layer.

The optical element may also include a substrate on the side of the second resin layer opposite the first resin layer.

The irradiation unit may have light sources arranged in a square array, and the optical element may have a pitch _P1 of the first lenses and a pitch _P2 of the second lenses such that _P1 = _P2 .

The irradiation unit may have light sources arranged in a hexagonal array, and the optical element may have a pitch _P1 of the first lenses and a pitch _P2 of the second lenses satisfying _2P1 = _√3P2 or _√3P1 = _2P2 .

In addition, the distances L ₁ and L ₂ are expressed by the following formulas 3 and 4.
It is preferable to satisfy the following.

The optical system device and optical element of the present invention can emit light with high contrast.

FIG. 13 is a diagram showing the orientation distribution at the far end of the irradiation unit used in the simulation. FIG. 1A is a schematic cross-sectional view showing a conventional optical system device, and FIG. 1B is a perspective view showing an aspheric lens. 1 is a graph showing the contrast of a conventional optical system device. 1 is a projection diagram of a dot pattern of a conventional optical system device. 1 is a schematic cross-sectional view showing an optical system device of the present invention. FIG. 1 is a perspective view showing an optical element of the present invention. FIG. 2 is a perspective view showing another optical element of the present invention. 1A and 1B are schematic cross-sectional views showing an optical system device of the present invention, and FIG. 1C is a perspective view showing a first lens and FIG. 4 is a projection diagram of a dot pattern of the optical system device of the present invention. 3A to 3C are schematic cross-sectional views illustrating a method for producing an optical element of the present invention. 5A to 5C are schematic cross-sectional views illustrating a method for producing another optical element of the present invention.

The optical system device of the present invention will be described below. As shown in FIG. 5, the optical system device of the present invention is mainly composed of an optical element 1 and an irradiation unit 2.

As shown in FIG. 6, the optical element 1 is mainly composed of a first lens layer 110 and a second lens layer 120.

The first lens layer 110 transmits light of wavelength λ and has periodically arranged linear first lenses 11. As shown in Fig. 5(a) , the first lenses 11 have a focal point that is spaced a focal length _f1 ( _f1 >0) from the side where the second lens layer 120 is not present.

The second lens layer 120 has linear second lenses 12 that transmit light of wavelength λ and are periodically arranged. The second lenses 12 are arranged so that the line direction is perpendicular to the line direction of the first lenses 11. As shown in Fig. 5(b) , the second lenses 12 have a focal point that is a focal length _f2 ( _f1 >0) away from the focal point on the first lens layer 110 side. In this specification, the focal length means the distance between the lens surface closest to the focal point and the focal point, as shown in Fig. 5 .

The first lens 11 and the second lens 12 may have any shape as long as they can focus light in a line shape, and for example, a lenticular lens may be used. In addition, the first lens 11 and the second lens 12 may be a Fresnel lens, a DOE lens, a metalens, or the like, as long as they can focus light in a line shape. In addition, the first lens 11 and the second lens 12 may be formed with an anti-reflection coating that prevents the light from the irradiation unit 2 from reflecting.

The first lens layer 110 is made of a material having a higher refractive index than the material on the side where light enters the first lens 11. The second lens layer 120 is made of a material having a higher refractive index than the material on the side where light enters the first lens 11. Therefore, when the first lens layer 110 and the second lens layer 120 are formed adjacent to each other, the first lens layer 110 needs to have a lower refractive index than the second lens layer 120. However, if the difference in refractive index between the first lens layer 110 and the air is small, it may be difficult to expand the dot pattern to a wide angle. In such a case, as shown in FIG. 7, an intermediate layer 130 having a lower refractive index than the materials of the first lens layer 110 and the second lens layer 120 may be provided between the first lens layer 110 and the second lens layer 120. This allows the first lens layer 110 to be made of a material having a large refractive index difference from air, so that the dot pattern can be expanded to a wide angle. The intermediate layer 130 may be made of a resin, but it is also possible to use a gas such as air or to create a vacuum.

As shown in Figures 6 and 7, the optical element 1 may have a substrate or the like on the side of the second resin layer opposite the first resin layer for manufacturing reasons or the like. The substrate may be made of any material that transmits light of wavelength λ, but it is preferable that the substrate be made of a material that has a lower refractive index than the first lens 11 and the second lens 12.

As shown in FIG. 5, the irradiation unit 2 has a light source 7 that irradiates the first lens 11 and the second lens 12 with light of wavelength λ. Any light source 7 that irradiates the first lens 11 and the second lens 12 with light of wavelength λ may be used. The irradiation unit 2 may be a single light source or multiple light sources. The irradiation unit 2 may be a multiple light source by passing the light of a single light source through an aperture having multiple pores. When the irradiation unit 2 is composed of multiple light sources, it is preferable that the light sources are formed on the same plane. A specific example of the irradiation unit 2 is a VCSEL (Vertical Cavity Surface Emitting LASER), which is expected to achieve high output with low power. The VCSEL has multiple light sources 7 that can irradiate light in a direction perpendicular to the light emitting surface. It is also preferable that a light absorbing film is formed on parts other than the light source 7, because noise due to reflected light is not introduced.

When the irradiation unit 2 has a plurality of light sources 7, they need to be arranged so that the number of light sources 7 for each first lens 11 of the optical element 1 and the number of light sources 7 for each second lens 12 of the optical element 1 are the same in a planar view even when the irradiation unit 2 and the optical element 1 are moved in parallel relative to each other. Therefore, when j is a natural number of 1 or more, the irradiation unit 2 may arrange the light sources 7 regularly with a pitch of _jP1 or _P1 /j in the periodic direction of the first lenses 11 of the optical element 1. Similarly, when k is a natural number of 1 or more, the irradiation unit 2 may arrange the light sources 7 regularly with a pitch of _kP2 or _P2 /k in the periodic direction of the second lenses 12 of the optical element 1.

Furthermore, in the optical element 1, when the light sources 7 of the irradiation unit 2 are arranged in a square array, the pitch _P1 of the first lenses 11 and the pitch _P2 of the second lenses 12 can be set to _P1 = _P2 . When the light sources 7 of the irradiation unit 2 are arranged in a hexagonal array, the pitch _P1 of the first lenses 11 and the pitch _P2 of the second lenses 12 can be set to _2P1 = _√3P2 or _√3P1 = _2P2 .

[Positional relationship between the irradiation unit and the optical element]
As shown in Fig. 2, the optical system device can convert the incident light into a dot pattern with high contrast when the distance _L1 between the irradiation unit 2 and the first focal plane 111 of the lens 11 and the distance _L2 between the irradiation unit 2 and the second focal plane 112 satisfy the following formulas α and β. Here, m and n are natural numbers of 1 or more, _P1 is the pitch size of the first lens 11, _P2 is the pitch size of the second lens 12, λ is the wavelength of the light incident from the irradiation unit 2, _f1 is the focal length of the first lens 11, _f2 is the focal length of the second lens 12, and a, b, c, and d are coefficients indicating allowable errors. The first focal plane 111 means a plane perpendicular to the optical axis (z direction) of the first lens 11 and at the focal position of the first lens 11. The second focal plane 121 means a plane perpendicular to the optical axis (z direction) of the second lens 12 and at the focal position of the second lens 12. The first lens 11 and the second lens 12 are formed so that the first focal plane 111 and the second focal plane 121 are parallel to each other. The distances _L1 and _L2 refer to the distance (optical path length) that light travels in a vacuum in the same time that it travels in a medium, and are expressed as the product NL, where N is the refractive index of the medium and L is the actual distance.

Here, the smaller the coefficient a in formula α is, the more preferable it is, a=1, a=0.5, a=0.3, a=0.1. The smaller the coefficient b is, the more preferable it is, b=1, b=0.5, b=0.3, b=0.1. The smaller the coefficient c in formula β is, the more preferable it is, c=1, c=0.5, c=0.3, c=0.1. The smaller the coefficient d is, the more preferable it is, d=1, d=0.5, d=0.3, d=0.1. When the coefficients of formula α and formula β are a=b=c=d=1, formula α and formula β become formula 1 and formula 2 below, respectively.

It is designed to satisfy.

More preferably, the distances L ₁ and L ₂ are expressed by the following formulas 3 and 4:

It is better to satisfy.

In addition, it is preferable that the distance between the first focal plane 111 and the second focal plane 121 of the optical element 1 is within 10 μm, since this makes it easier to simultaneously satisfy formulas 1 and 2 or formulas 3 and 4. It is also more preferable that the first focal plane 111 and the second focal plane 121 are in the same position.

Furthermore, when the distance between the first focal plane 111 and the second focal plane 121 is within 10 μm, it is preferable that in the optical element 1, the pitch P ₁ of the first lenses 11 and the pitch P ₂ of the second lenses 12 satisfy mP ₁ ² =nP ₂ ² .

[simulation]
Next, using the optical element 1 in which the first focal plane 111 of the first lens 11 and the second focal plane 121 of the second lens 12 are located at the same position, a simulation was performed on the light intensity distribution in the far field in the case where the distance _L1 between the irradiation unit 2 and the first focal plane 111 of the optical element 1 and the distance _L2 between the irradiation unit 2 and the second focal plane 121 satisfy the following formulas 3 and 4. The simulation was performed using optical simulation software BeamPROP (manufactured by Synopsys).

The irradiating unit 2 was a single light source that irradiated light with a wavelength of 940 nm (λ=0.94) and a light distribution as shown in FIG. 1. The optical element 1 transmits light with a wavelength λ, and has a first lens layer 110 having a linear first lens 11 and a second lens layer 120 having linear second lenses 12 arranged in a direction (X direction) perpendicular to the line direction (Y direction) of the first lens 11, with an intermediate layer 130 sandwiched therebetween, as shown in FIG. 8(a) and (b). As the first lens 11, as shown in FIG. 8(c), a lens having a refractive index of 1.53, a focal length f ₁ of 5 μm, and a periodic arrangement such that the pitch P ₁ was 32 μm (P ₁ =32) was used. As the second lens 12, as shown in FIG. 8(d), a lens having a refractive index of 1.53, a focal length f ₂ of 70 μm, and a periodic arrangement such that the pitch P ₂ was 32 μm (P ₂ =32) was used. The intermediate layer 130 has a refractive index of 1.42.

Figure 9 shows the projection diagram resulting from the simulation. As shown in Figure 8, the dots became very sharp and circular. In addition, the contrast was 123.2, which shows that the contrast can be improved significantly compared to conventional methods.

[Optical element manufacturing method]
The following describes a method for manufacturing the optical element 1. The first lens 11 and the second lens 12 of the optical element 1 may be manufactured in any manner, but may be manufactured, for example, by using an imprint method.

Specifically, first, the second lens 12 is formed on the substrate 9 using a known technique such as an imprint method (second lens formation step). For example, as shown in FIG. 10(a) and FIG. 11(a), the material 120a of the second lens 12 is applied to the substrate 9 with a predetermined thickness by a known method such as a spin coater (first application step). Any material 120a may be used as long as it can form the second lens 12 that transmits light of wavelength λ, and for example, photocurable polydimethylsiloxane (PDMS) can be used. Next, as shown in FIG. 10(b) and FIG. 11(b), a second mold 52 having a second lens pattern that is an inverted shape of the second lens 12 is prepared, and the applied material of the second lens 12 is pressed to transfer the second lens pattern (first transfer step). In addition, the applied pattern is cured by irradiating UV light or the like (first curing step). Next, as shown in Figures 10(c) and 11(c), the second mold 52 is released to form the second lens 12 on the substrate 9.

Next, the first lens 11 is formed on the second lens 12 using a known technique such as an imprint method (first lens formation process). For example, as shown in FIG. 10(e), a material 110a of the first lens 11 is applied to a predetermined thickness on the second lens 12 by a known method such as a spin coater (second application process). Any material 110a may be used as long as it can form the first lens 11 that transmits light of wavelength λ, and photocurable polydimethylsiloxane (PDMS) can be used, for example. Next, as shown in FIG. 10(f), a first mold 51 having a first lens pattern that is an inverted shape of the first lens 11 is prepared, and the applied material of the first lens 11 is pressed to transfer the first lens pattern (second transfer process). In addition, the applied pattern is cured by irradiating UV light or the like (second curing process). Next, as shown in FIG. 10(g), the first mold 51 is released, and the first lens 11 can be formed on the second lens 12.

It is also possible to form an intermediate layer 130 or the like on the second lens 12, and then form the first lens 11 on top of that. In this case, as shown in FIG. 11(d), a material 130a for the intermediate layer 130 is applied to a predetermined thickness on the second lens 12 by a well-known method such as a spin coater (intermediate layer application process). The material 130a is then hardened by irradiation with UV light or the like to form the intermediate layer 130 (intermediate layer hardening process).

Then, the first lens 11 is formed on the intermediate layer 130 using a known technique such as an imprinting method (first lens forming step). For example, as shown in FIG. 11(e), the material of the first lens 11 is applied to a predetermined thickness on the intermediate layer 130 by a known method such as a spin coater (second application step). Any material may be used as long as it can form the first lens 11 that transmits light of wavelength λ, and photocurable polydimethylsiloxane (PDMS) can be used, for example. Next, as shown in FIG. 11(f), a first mold 51 having a first lens pattern that is an inverted shape of the first lens 11 is prepared, and as shown in FIG. 11(g), pressure is applied to the applied material of the first lens 11 to transfer the first lens pattern (second transfer step). Also, UV light or the like is irradiated to harden the applied pattern (second hardening step). Next, as shown in FIG. 11(h), the first mold 51 is released, and the first lens 11 can be formed on the second lens 12.

It is preferable that the first lens 11 and the second lens 12 are formed so that the distance between the focal plane 111 of the first lens 11 and the focal plane 121 of the second lens 12 is within 10 μm, and more preferably, they are in the same position.

REFERENCE SIGNS LIST 1 optical element 2 irradiating unit 7 light source 9 substrate 11 first lens 12 second lens 51 first mold 52 second mold 110 first resin layer 111 first focal surface 120 second resin layer 121 second focal surface 130 third resin layer

Claims

an optical element including a first lens layer having first lenses that transmit light of wavelength λ and are periodically arranged in a line shape, and a second lens layer that is arranged in a direction perpendicular to the first lenses and has second lenses that transmit light of wavelength λ and are periodically arranged in a line shape;
an irradiation unit having a light source that irradiates light of a wavelength λ onto the first lens and the second lens;
Equipped with
Let m and n be natural numbers of 1 or more, the focal length of the first lens be f 1 , the focal length of the second lens be f 2 , the magnitude of the pitch of the first lens be P 1 , and the magnitude of the pitch of the second lens be P 2 , then the distance L 1 between the irradiation unit and the first focal plane of the first lens and the distance L 2 between the irradiation unit and the second focal plane of the second lens are expressed by the following formulas 1 and 2:

An optical system device characterized by satisfying the above.
The optical system device according to claim 1, characterized in that the distance between the first focal plane and the second focal plane of the optical element is within 10 μm.
3. The optical system apparatus according to claim 1 , wherein in the optical element, the pitch P1 of the first lens and the pitch P2 of the second lens satisfy mP12 = nP22 .
The optical system device according to claim 1 or 2, characterized in that the optical element has an intermediate layer between the first lens layer and the second lens layer, the intermediate layer having a lower refractive index than the materials of the first lens layer and the second lens layer.
The optical system device according to claim 1 or 2, characterized in that the first focal plane and the second focal plane of the optical element are located at the same position.
The illumination unit has light sources arranged in a square array,
3. The optical system apparatus according to claim 1, wherein in the optical element, a pitch P1 of the first lens and a pitch P2 of the second lens satisfy P1 = P2 .
The illumination unit has light sources arranged in a hexagonal array,
3. The optical system device according to claim 1, wherein in the optical element, a pitch P1 of the first lens and a pitch P2 of the second lens satisfy 2P1 = √3P2 or √3P1 = 2P2 .
The distances L 1 and L 2 are expressed by the following formulas 3 and 4:

3. The optical system according to claim 1, wherein the following is satisfied:
The optical system device according to claim 1 or 2, characterized in that the optical element has a substrate on the side of the second resin layer opposite the first resin layer.
a first lens layer that transmits light of wavelength λ and has linear first lenses that are periodically arranged;
a second lens layer including second lenses arranged in a direction perpendicular to the first lenses, the second lenses transmitting light of wavelength λ, and arranged periodically;
Equipped with
An optical element, characterized in that a distance between a first focal plane of the first lens and a second focal plane of the second lens is within 10 μm.
The optical element according to claim 10 , wherein m and n are natural numbers of 1 or more, a pitch of the first lens is P1 , and a pitch of the second lens is P2 , mP12 = nP22 is satisfied.
The optical element according to claim 10 or 11, characterized in that an intermediate layer having a lower refractive index than the materials of the first lens layer and the second lens layer is provided between the first lens layer and the second lens layer.
The optical element according to claim 10 or 11, characterized in that the first focal plane and the second focal plane are located at the same position.
The optical element according to claim 10 or 11, characterized in that the second resin layer is provided with a substrate on the opposite side to the first resin layer.