Metasurface lens and method for manufacturing same, and infrared hybrid refractive-metasurface quantum dot camera

Abstract

The present invention belongs to the technical fields of infrared imaging and micro-nano photonics, and disclosed is a metasurface lens and a method for manufacturing same, and an infrared hybrid refractive-metasurface quantum dot camera. The infrared hybrid refractive-metasurface quantum dot camera comprises a lens, a metasurface lens, a quantum dot infrared detector, and an optical lens assembling member which are sequentially arranged along an optical axis. A bonding process is used for the metasurface lens, thereby increasing the metasurface thickness and the mechanical stress that the metasurface lens can withstand. According to the present invention, only a simple two-lens optical structure is used, so that the simplification of an optical system is achieved, and the imaging quality of the optical system in the infrared band is ensured while enabling a broad range of use. Moreover, the optical system is combined with the quantum dot infrared detector, forming the infrared quantum dot camera.

Description

Metasurface lens, manufacturing method thereof, and infrared hyper-hybrid quantum dot camera TECHNICAL FIELD

[0001] The present application belongs to the technical field of infrared imaging and micro-nano photonics, and more particularly relates to a metasurface lens, a manufacturing method thereof, and an infrared hyper-hybrid quantum dot camera. BACKGROUND

[0002] Infrared imaging technology aims to capture the thermal radiation information of a target object through an infrared detector and convert it into a visible image. This technology is widely used in military night reconnaissance, infrared guidance, missile early warning, and other tasks, and also has a wide application prospect in the fields of security monitoring, vehicle night vision, and industrial detection in the civil field. Compared with traditional infrared detectors, quantum dot detectors have the advantages of long effective carrier lifetime, low dark current, high operating temperature, and response to vertical incident light, which can better identify and detect target objects.

[0003] In recent years, as the application of infrared imaging technology on mobile devices such as airborne and vehicle-mounted devices has gradually increased, there is an increasing demand for lightweight, simple structure, small size, and cost-effective infrared optical systems. In general, the current development trend of infrared imaging technology can be summarized as a more simplified system structure and stronger sensing ability.

[0004] However, traditional lenses face certain difficulties in further reducing the weight, size, and cost of infrared cameras due to their reliance on the shape of the element surface and the material optical properties to achieve control over the light wavefront. In this context, metasurfaces, as an emerging research direction in the field of nanophotonics, are expected to replace traditional lenses and achieve a more simplified infrared optical system. The structure of a metasurface is a two-dimensional periodic array of electromagnetic resonance units with subwavelength or wavelength scale, which can control the intensity, phase, polarization, and other parameters of electromagnetic waves in the entire electromagnetic spectrum. Compared with traditional optical elements, metasurface-based imaging technology, especially metasurface lenses, has the advantages of simple overall structure, cost-effective mass production, and better adaptation to planar processing technology, thus showing a wide application prospect in infrared imaging. The introduction of metasurface lenses is expected to further reduce the weight, size, and cost of infrared cameras.

[0005] However, current large-aperture metasurface lenses have the problem of insufficient lens thickness in practical applications. For example, Chinese patent CN113917578A discloses a large-aperture chromatic aberration correction hyperlens, a hyperlens system, and an optical system, wherein the hyperlens has a large aperture but an insufficient thickness of less than 2mm, which will lead to problems such as weakened optical system structure, reduced impact resistance, and easy deformation and distortion.

[0006] SUMMARY

[0007] In view of the above defects or improvement needs of the prior art, the present application provides an ultrathin lens and a manufacturing method and an infrared hyper-hybrid quantum dot camera, so as to realize the lightweight, simple structure, small size, cost economy of the current infrared quantum dot camera device and solve the technical problem of insufficient lens thickness of large-aperture ultrathin lens in practical application.

[0008] To achieve the above-mentioned purpose, according to one aspect of the present application, a manufacturing method of an ultrathin lens is provided, which uses a bonding process to increase the thickness of the ultrathin lens, reduce the diameter-thickness ratio, and thus improve the mechanical stress that the ultrathin lens can withstand, comprising the following steps:

[0009] Micro-nano structure arrays and bonding alignment marks are prepared on the front surface of the first wafer, and a film is plated on the front surface to protect the micro-nano structure arrays; bonding alignment marks are prepared on the front surface of the second wafer, and micro-nano structure arrays are prepared on the back surface, and a film is plated on the back surface to protect the micro-nano structure arrays;

[0010] The thickness of the third wafer is determined according to the aperture and transmittance requirements of the ultrathin lens, and the front and back surfaces of the third wafer are polished;

[0011] The first to third wafers are cleaned and heated, the back surface of the first wafer and the front surface of the second wafer are respectively aligned with the third wafer for light etching and heated pre-bonding and high-temperature annealing treatment, and finally the wafer after bonding is cleaned to remove the surface mask.

[0012] Optionally, the wafers are oscillation cleaned with organic cleaning agents such as acetone and ethanol, then the wafers are cleaned with corrosive cleaning agents such as hydrofluoric acid to remove the surface oxide layer, then the wafers are heated, then the wafers are treated with alkaline oxidizing solutions such as ammonia water and hydrogen peroxide to increase the number of hydroxyl groups adsorbed on the silicon wafer, which is beneficial to improve the bonding effect, and then the wafers are aligned for light etching and wafer bonding.

[0013] The present application provides an ultrathin lens, which is obtained by the above manufacturing method.

[0014] The present application provides an infrared hyper-hybrid quantum dot camera, which comprises a lens, an ultrathin lens, a quantum dot infrared detector and an optical lens assembly arranged in sequence along the optical axis.

[0015] The lens and the ultrathin lens form an optical lens group, the lens is used for converging incident light, and the converged incident light is focused on the focal plane of the quantum dot infrared detector after being corrected by the ultrathin lens.

[0016] The quantum dot infrared detector is used for eliminating stray light and incident light of non-target wave band and performing infrared detection imaging.

[0017] The lens and the metasurface lens are arranged in an optical lens assembly for fixing and protecting the lens and the metasurface lens.

[0018] Optionally, the lens is an aspheric lens, comprising a first aspheric surface and a second aspheric surface; surface coordinates Z1 and Z2 of the first aspheric surface and the second aspheric surface respectively satisfy:

[0019] wherein r is a distance from an arbitrary point on the aspheric lens to an optical axis of the optical imaging system; C1 and C2 are curvatures of the two corresponding spherical surfaces respectively; k1 and k2 are conic coefficients of the two corresponding spherical profiles respectively; X1, Y1, M1 and N1 are coefficients of four-order terms, six-order terms, eight-order terms and ten-order terms of the first aspheric surface respectively; X2, Y2, M2 and N2 are coefficients of four-order terms, six-order terms, eight-order terms and ten-order terms of the second aspheric surface respectively.

[0020] Optionally, the lens is a meniscus refractive lens with positive focal power.

[0021] The metasurface lens comprises a dielectric substrate layer and a columnar microstructure array, the columnar microstructure array is arranged in a hexagonal lattice or a tetragonal lattice periodic array by a plurality of columnar microstructure units; heights of the columnar microstructure units are all the same and are between a wavelength order of the target object thermal radiation; diameters of the columnar microstructure units are between a sub-wavelength order.

[0022] The quantum dot infrared detector comprises a detector window sheet, a filter sheet and an infrared photosensitive surface, the detector window and the infrared photosensitive surface are sequentially arranged along an optical axis direction; the detector window sheet and the filter sheet are used for eliminating stray light and incident light of non-target wave band; the infrared photosensitive surface is used for detecting and imaging the focused light.

[0023] The lens and the metasurface lens are arranged in the optical lens assembly, the optical lens assembly adopts a thread and a groove structure to fix and protect the lens and the metasurface lens, and facilitates structural adjustment of the optical system.

[0024] The optical lens assembly comprises a lens barrel body and a lens barrel outer wall, the groove structure in the lens barrel body has a buffer rubber material to shock-absorb and protect the optical system, and the lens barrel outer wall has a heat insulation material coating.

[0025] The phase distribution of the columnar microstructure unit periodic array satisfies the following expression: ​

[0026] wherein, p is the radial coordinate of the metasurface, R is the normalized radius, n is the maximum number of terms of the phase distribution, A i (i = 1, 2, 3, … n) are polynomial coefficients.

[0027] Optionally, the radius and height of the columnar microstructure unit at each position on the metasurface lens are determined according to the phase distribution of a hexagonal lattice or a square lattice periodic array.

[0028] Optionally, the metasurface lens is coated with an anti-reflection film layer on both the front and back surfaces, for anti-reflection of incident light and filtering of non-target wavelength incident light.

[0029] Optionally, the metasurface lens is a double-sided metasurface lens or a single-sided metasurface lens.

[0030] Optionally, the material of the columnar microstructure unit includes but is not limited to silicon, germanium or titanium dioxide; and the material of the dielectric substrate layer includes but is not limited to silicon, silicon dioxide or barium fluoride.

[0031] Optionally, the metasurface lens is prepared by a semiconductor process, and the metasurface preparation method includes but is not limited to ICP etching, photolithography and nanoimprint.

[0032] Optionally, the metasurface lens is bonded by a bonding process to increase the thickness of the metasurface lens, reduce the diameter-thickness ratio, and thus improve the mechanical stress that the metasurface lens can withstand, and the wafer bonding process, wherein the silicon-silicon bonding process includes:

[0033] Compared with the prior art, the above technical scheme of the present application can achieve the following beneficial effects:

[0034] 1. The present application provides a manufacturing method of a metasurface lens, wherein the metasurface lens can be prepared by a multi-piece bonding process, the thickness of the third wafer can be selected according to actual requirements, the thickness of the lens is increased, the diameter-thickness ratio is reduced to less than 10, and thus the mechanical stress that the metasurface lens can withstand and the structural strength and impact resistance of the metasurface lens are improved, the overall stability of the optical system is improved without affecting the optical performance of the system; at the same time, the metasurface lens is prepared by a semiconductor process, mass production can be realized, the optical processing precision and reliability are improved, and the batch production cost of the optical system is reduced.

[0035] 2. The prior art can provide chromatic aberration correction super lens exists super lens aperture is larger, but the thickness is insufficient, which will lead to optical system structure weakening, impact resistance is reduced, easy to appear variation and distortion and other problems, the present application realizes the combination of multiple super structure component wafers without modifying the existing equipment, improves the thickness of the super surface lens, thereby solving the technical problem of insufficient lens thickness of large aperture super surface lens in practical application.

[0036] 3. The infrared hyper-hybrid quantum dot camera provided by the present application has a double-piece structure in the optical lens part, and has simple system structure and easy assembly, and reduces the number of pieces compared with the traditional optical system; meanwhile, the system has excellent optical performance, and the modulation transfer function (MTF) is close to the diffraction limit, so that the combination of the simple lens structure and the small-pixel and large-array quantum dot infrared detector is realized, high-resolution infrared detection imaging is realized, and the imaging quality is good; the optical lens assembly uses thread and groove structure to fix and protect the lens and the super surface lens, and facilitates the adjustment of the structure of the optical system. BRIEF DESCRIPTION OF DRAWINGS

[0037] Fig. 1 is a structural schematic diagram of the infrared hyper-hybrid quantum dot camera according to the embodiment of the present application.

[0038] Fig. 2 is a structural schematic diagram of the super surface lens according to the embodiment of the present application.

[0039] Fig. 3 is a MTF curve diagram of the first optical system simulated according to the embodiment of the present application.

[0040] Fig. 4 is a spot column diagram at the photosensitive surface of the mid-infrared waveband quantum dot detector simulated according to the embodiment of the present application.

[0041] Fig. 5 is a MTF curve diagram of the second optical system simulated according to the embodiment of the present application.

[0042] Fig. 6 is a spot column diagram at the photosensitive surface of the near-infrared waveband quantum dot detector simulated according to the embodiment of the present application.

[0043] Fig. 7 is a flowchart of the super surface lens bonding process according to the embodiment of the present application.

[0044] In all the drawings, the same reference signs are used to represent the same elements or structures, in which: 1-lens; 2-super surface lens; 3-quantum dot infrared detector; 4-optical lens assembly. DETAILED DESCRIPTION

[0045] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0046] The structure of the electromagnetic super surface is a two-dimensional periodic array of electromagnetic resonance units with sub-wavelength or wavelength scale, which can regulate the intensity, frequency, phase, polarization and other parameters of electromagnetic waves in the whole electromagnetic spectrum. Compared with traditional optical elements, the imaging technology based on electromagnetic super surface, especially super surface lens, has the advantages of simple overall structure, low mass production cost and better adaptation to planar processing technology, so it has a wide application prospect in infrared imaging. The introduction of super surface lens is expected to further reduce the weight, volume and cost of infrared cameras, and its combination with traditional refractive lenses provides a new scheme for the design of infrared detection systems.

[0047] The content involved in the above embodiments will be described below in combination with a preferred embodiment.

[0048] Embodiment one

[0049] As shown in FIG. 1, the present application provides an infrared fold-super hybrid quantum dot camera, which comprises a lens 1, a super surface lens 2, an infrared quantum dot detector 3 and an optical lens assembly 4 placed in sequence along the direction of incident light;

[0050] The super surface lens 2 adopts a bonding process to improve the thickness of the super surface and its mechanical stress;

[0051] The quantum dot infrared detector 3 is used to eliminate stray light and incident light of non-target waveband and perform infrared detection imaging;

[0052] The lens 1 and the super surface lens 2 form an optical lens group, which is used to converge and focus the thermal radiation of a target object on the surface of the quantum dot infrared detector 3;

[0053] The refractive lens 1 and the super surface lens 2 are placed in the optical lens assembly 4, which adopts a thread and groove structure to fix and protect the lens and the super surface lens, and facilitates the structural adjustment of the optical system.

[0054] The super surface lens 2 comprises a dielectric substrate layer and a columnar microstructure array, as shown in FIG. 2, which is arranged in a hexagonal or tetragonal lattice periodic array by a plurality of columnar microstructure units; the height of the columnar microstructure units is all the same and is in the order of magnitude of the wavelength of the thermal radiation of the target object, and the diameter of the columnar microstructure units is in the order of magnitude of sub-wavelength.

[0055] The phase distribution of the periodic array of columnar microstructure units The following expression is satisfied:

[0056] Wherein, p is the radial coordinate of the super surface, R is the normalized radius, n is the maximum number of phase distribution, A i (i = 1, 2, 3, … n) are all polynomial coefficients.

[0057] Optionally, the diameter, period, height and arrangement mode of the columnar microstructure units are determined according to the corresponding phase distribution.

[0058] The infrared quantum dot detector used in this embodiment is used for imaging the focused infrared light, and the pixel size is 15 μm, and the pixel number or resolution is 640*512. When the MTF curve of the optical system approaches the diffraction limit and the cut-off frequency and the pixel pitch of the detector satisfy the formula: cut-off frequency = 1 / (2*pixel size), it means that the optical system and the detector are matched and the optical performance is good.

[0059] For example, in a specific embodiment, the infrared fold super hybrid quantum dot camera provided by the present application focuses and images in the mid-infrared waveband centered at 4.25 μm, 3.7-4.8 μm, the entrance pupil diameter of the optical system is 32.4 mm, the field of view is 5.4°, the focal length of the system is 63.2 mm, the F number is 2, and the total length of the optical system is not more than 64 mm. In the 3.7-4.8 μm waveband, the focal length changes less than 0.1%.

[0060] More specifically, in the first optical system provided by the embodiment of the present application, the specific parameter values are shown in Table 1, Table 2 and Table 3.

[0061] Table 1: Super surface lens parameters of the first optical system

[0062] Table 2: Structure parameters of the first optical system

[0063] Table 3: Conic coefficients and polynomial coefficients of the aspherical lens of the first optical system

[0064] The MTF curve diagram of the first optical system of the infrared fold super-hybrid quantum dot camera in the middle infrared wave band provided by the embodiment of the present application is shown in FIG. 3, and the MTF values of all fields of view are higher than 0.5 at the cutoff frequency of 34 lp / mm, the MTF curve is close to the diffraction limit, the system point diagram is shown in FIG. 4, the RMS radius is less than 6 microns, and the maximum chromatic aberration is less than 0.1%, so that near-diffraction limit imaging is realized.

[0065] In another specific embodiment, the infrared fold super-hybrid quantum dot camera provided by the present application realizes focused imaging in the middle infrared wave band with 1.55 microns as the center wavelength and 1.3-1.8 microns, the entrance pupil diameter of the optical system is 12 mm, the field of view angle is 5.4 degrees, the system focal length is 46.1 mm, the F number is 4, and the total length of the optical system is not more than 42 mm, and the focal length change is less than 0.12% in the 1.3-1.8 micron wave band.

[0066] More specifically, in the second optical system provided by the embodiment of the present application, the specific parameter values are shown in Table Four, Table Five and Table Six.

[0067] Table Four: Super surface lens parameter table of the second optical system

[0068] Table Five: Structure parameters of the second optical system

[0069] Table Six: Conic coefficients and polynomial coefficients of the aspheric lens of the second optical system

[0070] The MTF curve diagram of the second optical system of the infrared fold super-hybrid quantum dot camera in the near infrared wave band provided by the embodiment of the present application is shown in FIG. 5, and the MTF values of all fields of view are higher than 0.6 at the cutoff frequency of 34 lp / mm, the MTF curve is close to the diffraction limit, the system point diagram is shown in FIG. 6, the RMS radius is less than 4.2 microns, and the maximum chromatic aberration is less than 0.12%, so that near-diffraction limit imaging is realized.

[0071] The infrared fold super-hybrid quantum dot camera provided by the embodiment of the present application adopts the form of mixed refraction lens and super surface lens, the super surface lens modulates the incident light together with the refraction lens by virtue of its fine regulation ability, the optical system performance is excellent, the MTF curve is close to the diffraction limit, the F number matches the target detector, so that the combination with the infrared quantum dot detector is realized; the super surface lens manufactured by the design adopts the bonding process, the thickness of the super surface lens is improved, so that the mechanical stress, the structural strength and the impact resistance of the super surface lens are improved, and the overall stability of the optical system is improved without affecting the optical performance of the system.

[0072] Embodiment Two

[0073] The application also provides a manufacturing method of the metasurface lens, comprising:

[0074] The metasurface lens is prepared by a semiconductor process, and the metasurface preparation method includes but is not limited to ICP etching, photolithography, nanoimprint;

[0075] Optionally, the metasurface lens adopts a bonding process, and a flowchart is shown in FIG. 7, so as to increase the thickness of the metasurface lens, reduce the diameter-thickness ratio, and thus improve the mechanical stress that the metasurface lens can withstand. The wafer bonding process, wherein the silicon-silicon bonding flowchart comprises:

[0076] First, a mark position is reserved when a photolithography layout is drawn, a micro-nano structure array and an alignment mark are prepared on the front surface of a first piece of super-element wafer by using a step photolithography, deep silicon etching and other processes, a bonding alignment mark is prepared on the front surface of a second piece of super-element wafer by using a double-sided photolithography process, and a micro-nano structure array is prepared on the back surface of the second piece of super-element wafer; then, a surface film coating treatment is performed on the super-element to protect the micro-structure array on the surface thereof, a surface polishing high-purity silicon wafer is used, the thickness of the wafer is determined according to the aperture and transmittance requirements of the metasurface lens, and the silicon wafer is oscillation cleaned in an ultrasonic cleaner by using acetone and ethanol in sequence; then, the silicon wafer is cleaned by using hydrofluoric acid to remove the oxide layer on the surface of the silicon wafer, and then the silicon wafer is placed in a solution composed of concentrated sulfuric acid and hydrogen peroxide for heating treatment; after cleaning, the silicon wafer is treated by using ammonia water and hydrogen peroxide, and after cleaning, photolithography alignment is performed by using a photolithography machine, and heating pre-bonding and high-temperature annealing treatment are performed in a wafer bonding machine; finally, the bonded silicon wafer is cleaned by using a buffer oxide etching liquid to remove the surface mask.

[0077] The specific number of bonded pieces is determined according to the absorption coefficient of the substrate material in the target waveband, the system transmittance index requirement, and the diameter-thickness ratio required by the metasurface lens assembly.

[0078] The metasurface lens manufactured by the manufacturing method of the metasurface lens provided in the embodiment is applied in an infrared fold-hybrid quantum dot camera, and has the corresponding beneficial effects as in the above-mentioned embodiments.

[0079] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the application and is not intended to limit the application. Any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A method of manufacturing a metasurface lens, characterized by, The method comprises the following steps: Preparation of micro-nano structure array and bonding alignment mark on the front surface of the first wafer, and film plating on the front surface; Preparation of bonding alignment mark on the front surface of the second wafer, preparation of micro-nano structure array on the back surface, and film plating on the back surface; Polishing of the front and back surfaces of the third wafer according to the aperture and transmittance requirements of the metasurface lens to determine the thickness of the third wafer; Cleaning and heating treatment of the first to third wafers, lithographic alignment of the back surface of the first wafer and the front surface of the second wafer with the third wafer, heating pre-bonding, high-temperature annealing treatment, and finally cleaning of the bonded wafer to remove the surface mask.

2. A metasurface lens characterized in that, The metasurface lens is obtained by the manufacturing method of claim 1.

3. An infrared hypercam comprising a hybrid quantum dot camera, wherein, The lens (1), the metasurface lens (2) of claim 2, the quantum dot infrared detector (3), and the optical lens assembly (4) are sequentially arranged along the optical axis. The lens (1) is used for converging incident light, and the converged incident light is focused on the focal plane of the quantum dot infrared detector (3) after aberration correction by the metasurface lens (2). The quantum dot infrared detector (3) is used for eliminating stray light and non-target waveband incident light and performing infrared detection imaging. The lens (1) and the metasurface lens (2) are arranged in the optical lens assembly (4), and the optical lens assembly (4) is used for fixing and protecting the lens (1) and the metasurface lens (2).

4. The infrared hyperbolic meta-mix quantum dot camera of claim 1, wherein, The lens (1) is an aspherical lens or a meniscus refractive lens with positive focal power.

5. The infrared hyperbolic meta-mix quantum dot camera of claim 1, wherein, The metasurface lens (2) comprises a dielectric substrate layer and a columnar microstructure array arranged on both sides of the dielectric substrate layer, the columnar microstructure array comprises a plurality of columnar microstructure units arranged in a hexagonal lattice or a tetragonal lattice periodic array, the height of each columnar microstructure unit is the same and is in the order of magnitude of the wavelength of the target object thermal radiation, and the diameter and period of each columnar microstructure unit are in the order of magnitude of sub-wavelength. Phase distribution of a periodic array of columnar microstructure units satisfies the following expression: where p is the metasurface radial coordinate, R is the normalized radius, n is the maximum number of terms of the phase distribution, A i are polynomial coefficients, i = 1, 2, 3,... n.

6. The infrared hyperbolic meta-mix quantum dot camera of claim 5, wherein, The metasurface lens (2) is designed by the following method: The corresponding relationship between the size and phase distribution of the columnar microstructure unit in the metasurface lens and the transmittance is obtained by simulation, comprising: According to the finite difference time domain algorithm and the rigorous coupled wave analysis method, the size parameters of the columnar microstructure unit of the metasurface lens are simulated to determine the corresponding relationship between the height, period and diameter of the columnar microstructure unit and the phase distribution and transmittance.

7. The infrared hyper-angle hybrid quantum dot camera of claim 3, wherein, The front and back surfaces of the metasurface lens (2) are coated with an antireflection film layer of the target waveband.

8. The infrared hyperbolic meta-mix quantum dot camera of claim 5, wherein, The material of the columnar microstructure unit of the metasurface lens (2) is silicon, germanium or titanium dioxide, and the material of the dielectric substrate layer is silicon, silicon dioxide or barium fluoride.

9. The infrared hyperbolic meta-mix quantum dot camera of claim 3, wherein The quantum dot infrared detector (3) comprises a detector window sheet, a filter, a diaphragm and an infrared photosensitive surface arranged in sequence along the optical axis, the detector window sheet, the filter and the diaphragm are used for eliminating stray light and non-target waveband incident light, and the infrared photosensitive surface is used for detecting and imaging the focused light.

10. The infrared hyperbolic meta-mix quantum dot camera of claim 3, wherein, The optical lens assembly (4) comprises a lens barrel body and a lens barrel outer wall, the lens barrel body is internally provided with a groove structure for fixing a lens (1) and a metasurface lens (2), the groove structure is provided with a shock-absorbing material for shock-absorbing protection of the lens (1) and the metasurface lens (2); the lens barrel outer wall is provided with a heat insulation material coating.

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