Optical element, infrared optical system and infrared camera module

Abstract

The invention discloses an optical element, an infrared optical system and an infrared camera module, the optical element comprises a substrate, one surface of the substrate is provided with a convex surface, and the other surface of the substrate is provided with a sub-wavelength structure metasurface. The substrate is made of monocrystalline silicon, the convex surface of one surface of the substrate is prepared by adopting a semiconductor photoetching process, and the sub-wavelength structure metasurface of the other surface of the substrate is prepared by adopting the semiconductor photoetching process. One spherical surface and one metasurface are adopted to form an independent optical element, the structural mode can combine the advantages of the two surface types, the optical element is efficiently utilized, light focusing and aberration control are achieved, the imaging quality is improved, the cost is reduced, the weight of the system is reduced, and the size of the system is reduced.

Description

Technical Field

[0001] The present invention relates to the field of infrared optical imaging technology, and in particular to an optical element, an infrared optical system and an infrared camera module. Background Art

[0002] Infrared optical technology is a technology that uses infrared light for optical imaging and measurement. It is widely used in thermal imaging, remote sensing, medical diagnosis and other fields. With the rapid development of infrared technology, infrared cameras can achieve good imaging effects at night and in harsh environments, which has led to an increasing market demand for them. In addition to being widely used in the military field, in recent years, with the popularization of infrared detection technology, major breakthroughs have been made in important fields such as security monitoring, mapping and remote sensing, non-contact temperature measurement, outdoor sports, industrial inspection, and smart homes. Infrared optical lenses are one of the important components. The development of infrared imaging optical systems has also become a key factor in the development of infrared detection technology, requiring the thinning and miniaturization of infrared imaging equipment, that is, the number and structure of lenses in the optical imaging system need to be limited; requiring infrared imaging equipment to have lower and lower costs and high resolution and high performance, which also means that the optical system requires a lower cost and more cost-effective solution.

[0003] In related infrared imaging technologies, long-wave infrared lenses mainly use traditional methods to process optical components, such as cold processing, single-point turning or molding, and the materials are mainly germanium single crystals and chalcogenide materials.

[0004] The optical components processed in the above manner adopt the traditional design scheme, and each lens must have a certain optical focal length, that is, it must have a certain curvature and thickness. When the optical focal length distribution is insufficient or the aberration correction capability is insufficient, the number of lenses needs to be further increased. Therefore, it is not conducive to the realization of lightweight and miniaturization, and cannot effectively reduce the volume and weight. At the same time, the traditional design scheme has high material costs and high processing costs. At the same time, the production capacity and output are strictly limited by the processing capacity, which limits its cost to a range that can be widely used, limiting the application of infrared imaging technology in the civilian consumer market. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes an optical element, an infrared optical system and an infrared camera module. The use of the optical element of the present invention can reduce the size of the lens and reduce the manufacturing cost.

[0006] The technical solution of the present invention is implemented as follows: The present invention discloses an optical element, comprising a substrate, one side of the substrate having a convex surface, and the other side of the substrate having a sub-wavelength structured metasurface.

[0007] Furthermore, the phase distribution of the sub-wavelength structure metasurface satisfies the following expression:

[0008]

[0009] Wherein, ρ is the radial coordinate of the metasurface, R is the normalized radius, and A, B, C, D, E, F, G, H, and I are the coefficients of the quadratic, quartic, octadec, twelfth, fourteenth, sixteenth, and eighteenth terms of the phase mutation of the metasurface, respectively.

[0010] Furthermore, the subwavelength structured metasurface includes a nanopillar array, which is composed of a plurality of nanopillars with a fixed period T and height h.

[0011] Furthermore, the substrate material is single crystal silicon.

[0012] Furthermore, the convex surface and / or the sub-wavelength structure meta-structure surface is coated with an anti-reflection film.

[0013] The present invention also discloses an infrared optical system, comprising a first optical element and a second optical element arranged in sequence along the propagation direction of the optical axis, the first optical element and the second optical element adopt the optical elements as described above, wherein the object side surface of the first optical element has a convex surface, the image side surface of the first optical element has a sub-wavelength structure metasurface, the object side surface of the second optical element has a sub-wavelength structure metasurface, and the image side surface of the second optical element has a convex surface.

[0014] Further, the first optical element has negative optical power or positive optical power, and the second optical element has positive optical power.

[0015] Furthermore, the effective aperture of the convex surface of the first optical element is D2, and the effective aperture of the convex surface of the second optical element is D3;

[0016] The sag height of the object-side surface of the first optical element is Sag1, and the sag height of the image-side surface of the second optical element is Sag2;

[0017] 27.36≤D2 / |Sag1|≤54.55,15.16≤D3 / |Sag2|≤18.63.

[0018] Furthermore, the aspect ratio of the sub-wavelength structure metasurface ranges from 9.6 to 41.7.

[0019] Furthermore, the convex surfaces of the first optical element and the second optical element and the sub-wavelength structure meta-surface are coated with anti-reflection films.

[0020] Furthermore, the infrared optical system of the present invention further comprises an aperture, a detector protection window and a focal plane, wherein the aperture, the first optical element, the second optical element, the detector protection window and the focal plane are sequentially arranged along the propagation direction of the optical axis.

[0021] The invention also discloses an infrared camera module, which adopts the infrared optical system as described above.

[0022] The present invention has at least the following beneficial effects:

[0023] The present invention uses a spherical surface and a metasurface to form an independent optical element. This structural method can combine the advantages of two surface types to efficiently utilize the optical element, achieve light focusing and aberration control, and improve imaging quality.

[0024] The present invention adopts a structure of one spherical surface and one metasurface, which can give full play to the characteristic that the spherical surface can be coated with a hard protective film while providing sufficient design freedom, and is conducive to being placed at the outermost end, avoiding damage to the fragile subwavelength structure of the metasurface that affects the imaging quality, and effectively improving the environmental adaptability of the lens.

[0025] The present invention directly adopts a single-crystal silicon standard wafer, and through the photolithography and etching semiconductor process, the metasurface can be precisely designed and manufactured at the microscopic level, and has extremely high reproducibility. The spherical surface processing also adopts the photolithography and etching semiconductor process, which is compatible with the metasurface processing technology, thereby realizing the efficient production and application of optical components. This solution can not only ensure the imaging performance, but also fully utilize the photolithography technology to greatly reduce the production cost and mass production. The present invention uses an innovative optical architecture method to use an optical element that combines a spherical surface with a metasurface to replace a monolithic meta-optical element and a traditional optical element or replace an optical component composed of multiple traditional optical elements. This design can break through the problem of mutual constraints between parameters such as bandwidth, large aperture and high image quality in the current field of metasurface lenses. This solution can not only ensure the imaging performance, but also greatly reduce the production cost and system weight.

[0026] The infrared camera temperature measurement device composed of optical elements of this architecture adopted in the present invention can greatly reduce the size and weight of the device, which makes it easier to expand and integrate the device into consumer-grade application scenarios that focus on cost-effectiveness. This solution can not only ensure imaging performance, but also greatly reduce the user's usage cost and product experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of an infrared optical system provided by an embodiment of the present invention;

[0028] Figure 2 A spherical sag diagram of an optical element provided by an embodiment of the present invention;

[0029] Figure 3 A schematic diagram of nanorod parameters of an optical element provided by an embodiment of the present invention;

[0030] Figure 4 A schematic diagram of the aspect ratio of nanocolumns of an optical element provided by an embodiment of the present invention;

[0031] Figure 5 A schematic diagram of the nanocolumn distribution period of an optical element provided by an embodiment of the present invention;

[0032] Figure 6 A schematic diagram of the assembly of an infrared camera module provided by an embodiment of the present invention;

[0033] Figure 7 An exploded diagram of an infrared camera module provided by an embodiment of the present invention;

[0034] Figure 8 A schematic diagram of distortion of an infrared optical system provided by an embodiment of the present invention.

[0035] In the accompanying drawings, 1 is an aperture, 2 is a first optical element, 21 is an object side surface of the first optical element, 22 is an image side surface of the first optical element, 3 is a second optical element, 31 is an object side surface of the second optical element, 32 is an image side surface of the second optical element, 4 is a detector protection window, 5 is a focal plane, 6 is a lens barrel, 7 is a spacer ring, 8 is a lens mount, 9 is an infrared detector, 10 is a ceramic substrate, and 11 is an FPC. DETAILED DESCRIPTION

[0036] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0037] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. In the description of the present invention, unless otherwise specified, the meaning of "multiple" and "several" is two or more. Similarly, similar words such as "one", "one" or "the" do not indicate a quantity limit, but indicate the existence of at least one. Similar words such as "include" or "include" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Similar words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described target changes, the relative positional relationship may also change accordingly.

[0038] In each of the accompanying drawings, identical elements are represented by similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not all drawn to scale. In addition, some well-known parts may not be shown in the drawings.

[0039] Many specific details of the present invention are described below, such as component structures, materials, dimensions, processing techniques and technologies, in order to more clearly understand the present invention. However, as those skilled in the art will appreciate, the present invention may be implemented without following these specific details.

[0040] Embodiment 1

[0041] See also Figures 1 to 5 The present invention discloses an optical element, comprising a substrate, one side of the substrate having a convex surface, and the other side of the substrate having a sub-wavelength structured metasurface.

[0042] Furthermore, the convex surface can be a spherical surface or an aspherical surface. Since it is difficult to ensure the surface quality in the current process of aspherical surface processing, which affects the final imaging effect, preferably, the convex surface of the present invention is a spherical surface, and the present invention mainly adopts a spherical surface for design and development.

[0043] The optical element of the present invention adopts a spherical-metasurface combination. Compared with an optical system composed of pure metasurfaces, the optical element of the present invention after adding a spherical surface can, firstly, concentrate most of the optical focal length on the spherical surface, and the metasurface only needs to bear a small amount of focusing function, thereby reducing the influence of the chromatic aberration of the metasurface itself on the chromatic aberration of the system; secondly, due to the addition of a spherical surface with a variable design curvature, the metasurface can have a larger range of variation in wavefront control, and the phase distribution is freer, which has a greater correction effect on aberrations.

[0044] The present invention can obtain the phase change characteristics of different sizes and shapes of metasurface units at different wavelengths in the working band by scanning, and form a metasurface unit library. According to the dispersion characteristic requirements of the metasurface at each position given by the optical system, the required metasurface unit is selected from the library.

[0045] Furthermore, the phase distribution of the sub-wavelength structure metasurface satisfies the following expression:

[0046]

[0047] Wherein, ρ is the radial coordinate of the metasurface, R is the normalized radius, and A, B, C, D, E, F, G, H, and I are the coefficients of the quadratic, quartic, octadec, twelfth, fourteenth, sixteenth, and eighteenth terms of the phase mutation of the metasurface, respectively.

[0048] Further, the subwavelength structure metasurface includes a nanocolumn array, which is composed of a number of nanocolumns with a fixed period T and a height h, that is, the subwavelength structure metasurface of the present invention is arranged in a nanocolumn array with a period of T and a height of h. The arrangement of the nanocolumn array is a quadrilateral periodic arrangement or a hexagonal periodic arrangement. In addition to quadrilateral and hexagonal periodic arrangements, there are nanocolumn arrays of other shapes and arrangements.

[0049] The shape of the nanorods of the present invention can be a variety of different shapes, such as circular, circular ring, square or square ring, to meet the requirements of different metasurface width dispersion control.

[0050] In terms of the morphology of the metasurface unit, the height h of the metasurface unit can be selected to be between 5-15 μm, the period can be selected to be between 2.5-3.5 μm, and the aspect ratio of the metasurface unit is less than or equal to 50.

[0051] The aspect ratio is the ratio of the height perpendicular to the processing surface to the smallest feature size on the processing surface. For example, the aspect ratio is the ratio of the height of the nanocolumn to the diameter of the nanocolumn or the height of the nanocolumn to the spacing between the nanocolumn lenses.

[0052] Further, see Figure 5 , the nanocolumns are arranged in a period T, and the diameter of the nanocolumns is D n , the air spacing of the nanorods is d n , and T = d n +D n . n is a positive integer, i.e. 1, 2, 3...i. The minimum column spacing d1 = 0.3 μm, the nanocolumn height h = 12.5 μm. The maximum column spacing d i =1.3μm, nanocolumn height h=12.5μm.

[0053] Furthermore, the aspect ratio of the sub-wavelength structure metasurface is in the range of h / maximum column spacing d i (e.g. 9.6) to h / minimum column spacing d1 (e.g. 41.7).

[0054] Furthermore, the optical element substrate is made of single crystal silicon.

[0055] Furthermore, the optical element is formed by photolithography and etching of a whole silicon wafer.

[0056] Furthermore, the surfaces of the optical elements are prepared by semiconductor processes such as photolithography or nanoimprinting.

[0057] Furthermore, the convex surface on one side of the substrate is prepared by photolithography and etching semiconductor technology, and the sub-wavelength structure metasurface on the other side of the substrate is prepared by photolithography and etching semiconductor technology.

[0058] The present invention uses an innovative optical architecture and photolithography and etching semiconductor process to use an optical element that combines a spherical surface with a metasurface to replace a monolithic meta-optical element and a traditional optical element or to replace an optical assembly composed of multiple traditional optical elements. This design can break through the problem of mutual constraints between bandwidth, large aperture, and high image quality parameters in the current metasurface lens field. This solution can not only ensure imaging performance, but also significantly reduce production costs and system weight.

[0059] Furthermore, the convex surface and / or the sub-wavelength structure meta-structure surface is coated with an anti-reflection film.

[0060] Embodiment 2

[0061] See also Figures 1 to 5 The present invention discloses an infrared optical system, including a propagation direction along an optical axis I (such as Figure 1 As shown in the figure, from left to right, a first optical element 2 with negative optical focal power or positive optical focal power and a second optical element 3 with positive optical focal power are arranged in sequence. The first optical element 2 and the second optical element 3 are optical elements as described in Example 1, wherein the object side surface 21 of the first optical element 2 has a convex surface (convex surface in the area near the optical axis), the image side surface 22 of the first optical element 2 has a subwavelength structure metasurface, the object side surface 31 of the second optical element 3 has a subwavelength structure metasurface, and the image side surface 32 of the second optical element 3 has a convex surface (convex surface in the area near the optical axis).

[0062] Preferably, the convex surface of the object-side surface 21 of the first optical element 2 is a spherical surface.

[0063] Preferably, the convex surface of the image side surface 32 of the second optical element 3 is a spherical surface.

[0064] Furthermore, the phase distributions φ1 and φ2 of the sub-wavelength structure metasurfaces of the first optical element 2 and the second optical element 3 respectively satisfy the following expressions:

[0065]

[0066] Wherein, ρ is the radial coordinate of the metasurface, R is the normalized radius, A1, B1, C1, D1, E1, F1, G1, H1, I1 are respectively the coefficients of the second order, fourth order, sixth order, eighth order, tenth order, twelveth order, fourteenth order, sixteenth order, and eighteenth order of the metasurface phase mutation of the image side surface 22 of the first optical element 2, and A2, B2, C2, D2, E2, F2, G2, H2, I2 are respectively the coefficients of the second order, fourth order, sixth order, eighth order, tenth order, twelveth order, fourteenth order, sixteenth order, and eighteenth order of the metasurface phase mutation of the object side surface 31 of the second optical element 3. The metasurface coefficients of the three embodiments are shown in Table 1, Table 2, and Table 3.

[0067] Table 1 Metasurface coefficients of the first embodiment

[0068]

[0069] Table 2 Metasurface coefficients of the second embodiment

[0070]

[0071] Table 3 Metasurface coefficients of the third embodiment

[0072]

[0073] Further, the convex effective aperture of the first optical element 2 is D2, and the convex effective aperture of the second optical element 3 is D3; the sagitta of the object side surface 21 of the first optical element 2 is Sag1, and the sagitta of the image side surface 32 of the second optical element 3 is Sag2;

[0074] 27.36≤D2 / |Sag1|≤54.55,15.16≤D3 / |Sag2|≤18.63;

[0075] When the above relationship is out of range, the processing difficulty will increase sharply and the production yield will drop sharply, which is not conducive to cost reduction.

[0076] Furthermore, the convex surface and the sub-wavelength structure metasurface of the first optical element 2 and the second optical element 3 are coated with an anti-reflection film. The convex surface (or spherical surface) and the metasurface are coated with multiple layers of anti-reflection film to achieve higher transmittance, reduce reflection and scattering losses, and improve the imaging quality of the system.

[0077] The object side surface of the first optical element 2 is a spherical surface, which bears part of the optical power to focus the light angles of each field of view. The image side surface of the second optical element 3 is a spherical surface, which bears part of the optical power and effectively improves the ability of the edge light beam to be incident on the detector focal plane 5.

[0078] The image side surface of the first optical element 2 and the object side surface of the second optical element 3 are metasurfaces. By adjusting the periodic size and height of the nanocolumns, the phase of each field of view light is modulated so that the dispersion characteristics in the 8-12μm working band are close to consistent, and spherical aberration, coma, field curvature and astigmatism are corrected.

[0079] The focal length of the first optical element 2 is f1, and the focal length of the second optical element 3 is f2, wherein f1<0 or f1>0, and f2>0.

[0080] Furthermore, the infrared optical system of the present invention also includes an aperture stop 1, a detector protection window 4 and a focal plane 5, and the aperture stop 1, the first optical element 2, the second optical element 3, the detector protection window 4, and the focal plane 5 are arranged in sequence along the propagation direction of the optical axis I.

[0081] Furthermore, a plurality of such optical elements are arranged together according to the designed optical system sequence and interval, and fixed by a precision positioning device to form an optical system. The metasurface coefficients of an embodiment are shown in Table 2, Table 3, and Table 4, and the distortion diagram thereof is shown in Figure 8 shown.

[0082] Table 2 shows the optical system parameters of the first embodiment.

[0083]

[0084] Among them, Sag1 = 0.022, Sag2 = -0.107, f1 = -61.03, f2 = 1.229

[0085] D2 / |Sag1|=54.55; D3 / |Sag2|=17.6; TTL / f=2.336

[0086] Table 3 shows the optical system parameters of the second embodiment.

[0087]

[0088] Among them, Sag1 = 0.0199, Sag2 = -0.105, f1 = 3.11, f2 = 1.125

[0089] D2 / |Sag1|=50.75; D3 / |Sag2|=15.16; TTL / f=2.863

[0090] Table 4 shows the optical system parameters of the third embodiment.

[0091]

[0092]

[0093] Among them, Sag1 = 0.044, Sag2 = -0.109, f1 = -3.711, f2 = 0.907

[0094] D2 / |Sag1|=27.36; D3 / |Sag2|=18.63; TTL / f=2.408

[0095] Embodiment 3

[0096] See also Figures 1 to 7 , an infrared camera module, adopts the infrared optical system as described in Example 2.

[0097] The infrared camera module includes a lens base 8, a lens barrel 6, and a substrate. The lens base 8 is fixed on the substrate. An infrared detector 9 is arranged on the substrate. The lens barrel 6 is fixedly connected to the upper end of the lens base 8. The first optical element 2 and the second optical element 3 of the infrared optical system are fixed in the lens barrel 6 and are located directly above the infrared detector 9. The substrate is connected to the FPC 11. The substrate is a ceramic substrate 10.

[0098] A spacer ring 7 is disposed in the lens barrel 6 , and the spacer ring 7 is located between the first optical element 2 and the second optical element 3 .

[0099] The focal length of the optical lens is f, the total length of the optical lens is TTL, and 2.3 <TTL / f<2.9。

[0100] The present invention reduces costs, and the specific analysis is as follows: The present invention uses innovative architecture and photolithography processing methods to perform semiconductor processing on standard wafers, which greatly reduces the cost of mass production while ensuring imaging performance. This is because the spherical surface and metasurface used in the present invention are both realized by process-compatible semiconductor processing technology, and metasurface technology is used. This technology can greatly improve the design freedom of optical devices and realize functions that traditional optical components cannot achieve, thereby reducing the demand for complex optical components and reducing production costs.

[0101] The present invention reduces the weight of the system. The specific analysis is as follows: The present invention can greatly reduce the weight of the system by using a spherical surface and a metasurface to form an independent optical element. This is because the metasurface technology can achieve flexible control of the phase, amplitude, polarization and other characteristics of light, thereby making the design of optical elements more flexible, reducing the number of traditional optical elements used, and reducing the weight of the system.

[0102] The present invention reduces the volume of the system, and the specific analysis is as follows: The present invention can greatly reduce the volume of the infrared camera temperature measurement device composed of optical elements of this structure. This is because the metasurface technology can greatly improve the design freedom of optical devices, so that the traditional thick spherical lens can be replaced by an extremely thin silicon wafer sheet, and the spatial distribution of optical elements can be arranged more reasonably, reducing the volume of the system.

[0103] The present invention expands the application scenarios, and the specific analysis is as follows: Through the improvements in the above three aspects, the present invention can enable the infrared optical system to meet the requirements of miniaturization and lightweight while also ensuring imaging performance, thereby expanding to more consumer-level application scenarios that focus on cost-effectiveness.

[0104] Due to the advanced nature of the present invention, it can be widely used in application fields such as optical lens design, metasurface technology, and infrared optical technology. First, the present invention can significantly reduce the cost of mass production and greatly reduce the weight of the system while ensuring imaging performance through innovative structural methods and photolithography processing methods, which has important practical value for the field of optical lens design. Secondly, the metasurface technology of the present invention can greatly improve the design freedom of optical devices and realize functions that traditional optical components cannot achieve, which has important research and application value for the field of metasurface technology. Finally, the infrared optical system of the present invention can ensure imaging performance while meeting miniaturization and lightweight requirements, which has important application prospects for the field of infrared optical technology. At the same time, with the development of science and technology and the improvement of consumer demand for product performance, the demand for lightweight, compact, and high-performance optical equipment is increasing, and the application prospects of the present invention are very broad.

[0105] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An optical element, characterized in that: The invention comprises a substrate, one side of the substrate has a convex surface, and the other side of the substrate has a sub-wavelength structured metasurface.

2. The optical element according to claim 1, characterized in that: The phase distribution of the sub-wavelength structure metasurface satisfies the following expression: Wherein, ρ is the radial coordinate of the metasurface, R is the normalized radius, and A, B, C, D, E, F, G, H, and I are the coefficients of the quadratic, quartic, octadec, twelfth, fourteenth, sixteenth, and eighteenth terms of the phase mutation of the metasurface, respectively.

3. The optical element according to claim 1, characterized in that: The subwavelength structured metasurface includes a nanopillar array, which is composed of a number of nanopillars with a fixed period T and height h.

4. The optical element according to claim 1, characterized in that: The substrate material is single crystal silicon.

5. An infrared optical system, characterized in that: It comprises a first optical element and a second optical element which are sequentially arranged along the propagation direction of the optical axis, wherein the first optical element and the second optical element are optical elements as described in any one of claims 1 to 4, wherein the object side surface of the first optical element has a convex surface, the image side surface of the first optical element has a sub-wavelength structure metasurface, the object side surface of the second optical element has a sub-wavelength structure metasurface, and the image side surface of the second optical element has a convex surface.

6. The infrared optical system according to claim 5, characterized in that: The first optical element has negative optical power or positive optical power, and the second optical element has positive optical power.

7. The infrared optical system according to claim 5, characterized in that: The effective aperture of the convex surface of the first optical element is D2, and the effective aperture of the convex surface of the second optical element is D3; The sag height of the object-side surface of the first optical element is Sag1, and the sag height of the image-side surface of the second optical element is Sag2; 27.36≤D2 / |Sag1|≤54.55,15.16≤D3 / |Sag2|≤18.

63.

8. The infrared optical system according to claim 5, characterized in that: The aspect ratio of the subwavelength structure metasurface ranges from 9.6 to 41.

7.

9. The infrared optical system according to claim 5, characterized in that: It also includes an aperture, a detector protection window and a focal plane, wherein the aperture, the first optical element, the second optical element, the detector protection window and the focal plane are arranged in sequence along the propagation direction of the optical axis.

10. An infrared camera module, characterized in that: An infrared optical system as described in any one of claims 5 to 9 is used.

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