Heat radiator based on miniature parabolic mirror array and preparation method thereof

Abstract

The invention provides a heat radiator based on a miniature parabolic mirror array and a preparation method of the heat radiator. The heat radiator based on the miniature parabolic reflector array comprises a miniature parabolic reflector array part and a multilayer film absorption part which are arranged up and down, the miniature parabolic reflector array part comprises a plurality of parabolic reflectors arranged in an array, the lower end of each parabolic reflector is provided with a focal plane opening at the focal plane position, and the multilayer film absorption part is arranged on the lower end of each parabolic reflector. The multi-layer film absorption part comprises a wavelength selective absorption multi-layer film, and the upper surface of the wavelength selective absorption multi-layer film is attached to the edges of all focal plane openings. According to the invention, the directivity of emitted light is regulated and controlled, and polarization insensitive heat radiation is concentrated in the small-angle direction of vertical emission, so that small-angle broadband high emissivity matched with a thermophotovoltaic cell is realized, and low emissivity is realized at other angles; meanwhile, the TPV system is not sensitive to light polarization, the angle selection efficiency of the system is improved, and the energy conversion efficiency of the TPV system is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of radiation cooling, and in particular relates to a heat radiator based on a micro parabolic reflector array and a preparation method thereof. Background Art

[0002] Thermophotovoltaic (TPV) is a technology that converts thermal energy into electrical energy. It uses the radiation emitted by a high-temperature heat source to be absorbed by a photovoltaic cell, and then directly converts the light energy into electrical energy through the photoelectric effect. Thermophotovoltaic cells include GaSb (gallium antimonide) photovoltaic cells with a bandgap energy of 0.72eV and an absorption cutoff wavelength of 1.72μm, InGaAs (indium gallium arsenide) photovoltaic cells with a bandgap energy of 0.60eV and an absorption cutoff wavelength of 2.07μm, and Ge (germanium) photovoltaic cells with a bandgap energy of 0.6eV and an absorption cutoff wavelength of 1.88μm.

[0003] Thermal radiators are key components in TPV systems. They must not only match the bandgap wavelength of photovoltaic cells to optimize absorption efficiency, but also have angle selectivity and polarization insensitivity to reduce energy loss. In addition, the material and structural design of thermal radiators play an important role in the overall efficiency and economy of the system. Therefore, the selection and design of thermal radiators often determine the performance of TPV systems and the feasibility of practical applications.

[0004] Traditional thermal radiators often have problems with scattered emission energy and low energy utilization, especially in non-vertical directions, where the radiation energy not captured by photovoltaic cells is easily lost. For example, angle-selective thermal radiators based on gradient ENZ material multilayer films are not only complex in design and difficult to manufacture, but also expensive and sensitive to polarization states, with angle selection limited to P-polarized waves. However, since thermal radiation light is unpolarized light, this results in an angle selection efficiency of only 50% at most.

[0005] The relationship between the radiant energy of thermal radiation and wavelength is usually given by Planck's radiation law:

[0006]

[0007] Among them, I BB (λ, T) represents the radiation intensity when the wavelength is λ, h is Planck's constant, c is the speed of light; k B is the Boltzmann constant, and T is the temperature of the radiator.

[0008] The emissivity of the thermal radiator and the effective radiation absorption efficiency of the thermal photovoltaic system can be given by the following formula:

[0009]

[0010] E=hc / λ

[0011] E g =hc / λ g

[0012] Where T is the temperature of the high temperature heat source, usually between 1000K-2000K; ε(E, θ) is the emissivity of the thermal radiator with the energy E and the emission angle θ corresponding to the emission wavelength, Eg is the band gap energy of the thermal photovoltaic cell, θ c is the absorption cutoff angle determined by the geometric size and distance of the thermal radiator and the thermal photovoltaic cell, θ is the radiation direction of the thermal radiator, I BB (E, T) is the blackbody radiation corresponding to the radiation energy at the working temperature of the heat source.

[0013] According to the radiation absorption efficiency formula, it can be found that wavelength selectivity and angle selectivity are both important factors in improving the efficiency of thermophotovoltaic systems. Wavelength selectivity ensures that the emitted light energy is concentrated in the optimal absorption wavelength range of the thermophotovoltaic cell, while angle selectivity ensures that the radiation energy is concentrated in the angle range that can be absorbed by the thermophotovoltaic cell, thereby improving the overall conversion efficiency.

[0014] However, the design of traditional thermal radiators usually focuses on optimizing the wavelength range of the emission spectrum, that is, concentrating the emitted radiation energy within the wavelength range that can be effectively absorbed by the thermophotovoltaic cell. This range is usually related to the band gap Eg of the thermophotovoltaic cell. According to the formula, the lower limit of the integral Eg represents the band gap energy of the thermophotovoltaic cell. If the thermal radiator can adjust the emissivity at wavelengths near the energy above Eg, such a design can improve the conversion efficiency because it will reduce the integral value of the denominator in the formula for energy below the band gap. Traditional thermal radiators are generally not selective for the angle of thermal radiation, which will result in the integration of thermal radiation at large angles in the denominator, making the denominator larger and reducing the system efficiency.

[0015] Therefore, most thermal radiators currently have omnidirectional thermal radiation effects, and there is little research on directional thermal radiation. Most radiation cooling devices use multilayer thin films, super-surface micro-nano structures and other types of structures that have high emissivity in the near-infrared wavelength that is smaller than the energy band gap of thermal photovoltaic cells, and low emissivity in the wavelength that is larger than the energy band gap of thermal photovoltaic cells. These structures have no selectivity for emissivity at different angles. Summary of the invention

[0016] In order to solve the above-mentioned deficiencies of the prior art, the main purpose of the present invention is to provide a thermal radiator based on a micro parabolic reflector array and a preparation method thereof.

[0017] According to Kirchhoff's law of thermal physics, under thermal equilibrium, the emissivity is numerically equal to the absorptivity, and the direction of thermal radiation is consistent with the direction of thermal photon absorption. Therefore, the present invention uses the basic physical law of a parabola to converge parallel light on the focal plane, and achieves the inverse design goal of thermal radiation approximation in the focal plane and emission in the vertical direction. In combination with the specific application scenarios of high-temperature radiators, the invention comprehensively considers the band selection, material selection, device design and preparation and processing, and carries out a large number of tedious system designs and calculation verifications, thereby proving the feasibility of the design scheme and preparation process.

[0018] To achieve the above object, the present invention adopts the following technical solutions:

[0019] <Option 1>

[0020] The present invention provides a thermal radiator based on a micro parabolic reflector array, which has the following characteristics: a micro parabolic reflector array portion and a multilayer film absorption portion which are arranged in an upper and lower manner, wherein the micro parabolic reflector array portion includes a plurality of parabolic reflectors arranged in an array, and the lower end of each parabolic reflector is provided with a focal plane opening at the focal plane position, and the multilayer film absorption portion includes a wavelength selective absorption multilayer film, and the upper surface of the wavelength selective absorption multilayer film is attached to all the edges of the focal plane openings.

[0021] The heat radiator based on the micro parabolic reflector array provided by the present invention may also have the following features: wherein the height of the parabolic reflector is 20-500 μm, and the curvature is 0.05-0.1 μm -1 .

[0022] In the thermal radiator based on the micro parabolic reflector array provided by the present invention, it can also have the following characteristics: wherein, the micro parabolic reflector array part also includes a reflector substrate made of refractory metal, and a plurality of substrate parabolic through holes arranged in an array and respectively matching the plurality of parabolic reflectors are formed on the reflector substrate, and each parabolic reflector is formed by a refractory metal reflective film plated on the inner wall of the corresponding substrate parabolic through hole.

[0023] In the thermal radiator based on the micro parabolic reflector array provided by the present invention, it can also have the following characteristics: wherein, the multiple parabolic reflectors and the multiple substrate parabolic through holes are a hexagonal close-packed structure of circular paraboloids, a hexagonal close-packed structure of hexagonal paraboloids, or a triangular close-packed structure of triangular paraboloids.

[0024] The thermal radiator based on the micro parabolic reflector array provided by the present invention may also have the following feature: the upper surface of the reflector substrate except for the parabolic through holes of the substrate is also plated with a refractory metal reflective film.

[0025] The thermal radiator based on the micro parabolic reflector array provided by the present invention may also have the following feature: an anti-oxidation film is provided on the inner surface of the parabolic reflector.

[0026] The thermal radiator based on the micro parabolic reflector array provided by the present invention may also have the following feature: wherein the wavelength selective absorption multilayer film is a three-layer film structure.

[0027] In the thermal radiator based on the micro parabolic reflector array provided by the present invention, it can also have the following characteristics: wherein the multilayer film absorption part further includes a refractory metal substrate arranged on the lower surface of the wavelength selective absorption multilayer film.

[0028] <Option 2>

[0029] The present invention also provides a method for preparing a thermal radiator based on a micro parabolic reflector array, which has the following characteristics and comprises the following steps:

[0030] Step S1, coating a wavelength selective absorption multilayer film on a refractory metal substrate;

[0031] Step S2, coating a refractory metal layer on the wavelength selective absorption multilayer film as a reflector substrate;

[0032] Step S3, spin coating a photoresist layer on the reflector substrate, and preparing a plurality of parabolic microholes arranged in an array on the photoresist layer;

[0033] Step S4, transferring the pattern of the plurality of parabolic microholes on the photoresist layer to the reflector substrate by etching, thereby forming a plurality of substrate parabolic through holes arranged in an array on the reflector substrate;

[0034] Step S5, tilting the semi-finished product obtained in step S4 twice, and plating a refractory metal reflective film on the inner wall of the parabolic through hole of the substrate to form a parabolic reflector;

[0035] Step S6, tilting the semi-finished product obtained in step S5 twice, coating an anti-oxidation film on the inner surface of the parabolic reflector, thereby obtaining a finished product of a heat radiator based on a micro parabolic reflector array.

[0036] Compared with the prior art, the advantages of the present invention are: by regulating the directionality of the emitted light to focus on the polarization-insensitive thermal radiation at a small angle of vertical emission, unnecessary energy loss is effectively reduced, and a small-angle wide-band high emissivity matching the thermal photovoltaic cell is achieved, while low emissivity is achieved at other angles. At the same time, it is insensitive to the polarization of light, which improves the efficiency of the system's angle selection and effectively improves the energy conversion efficiency of the TPV system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic structural diagram of a heat radiator based on a micro parabolic reflector array in the present invention;

[0038] Figure 2 It is a schematic diagram of the structure of the parabolic reflector and the wavelength selective absorption multilayer film in the present invention;

[0039] Figure 3 is the transmittance of incident light at different angles through the parabolic reflector in the present invention;

[0040] Figure 4 is the wavelength-dependent absorptivity of the wavelength-selective multilayer film of the present invention;

[0041] Figure 5 is an oblique cross-sectional view of a parabolic reflector arranged in a hexagonal close-packed structure of a circular parabola in an embodiment of the present invention;

[0042] Figure 6 is a top view of an oblique cross-sectional view of a parabolic reflector arranged in a hexagonal close-packed structure of a circular parabola in an embodiment of the present invention;

[0043] Figure 7 is the absorptivity of the embodiment of the present invention under incident light at different angles;

[0044] Figure 8 A schematic diagram of a structure in which a parabolic reflector is arranged in a hexagonal close-packed structure of hexagonal paraboloids in a first variation of the present invention; and

[0045] Fig. 9 It is a schematic structural diagram of the close-packed structural arrangement of the triangular paraboloids of the parabolic reflector in the second variant of the present invention. DETAILED DESCRIPTION

[0046] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention.

[0047] like Figure 1 As shown, the present invention provides a thermal radiator based on a micro parabolic reflector array, comprising a micro parabolic reflector array portion and a multilayer film absorption portion arranged in an upper and lower manner.

[0048] like Figure 1 As shown, the micro parabolic reflector array portion includes a plurality of parabolic reflectors 01 and a reflector substrate 03 .

[0049] A plurality of parabolic reflectors 01 are arranged in an array; a focal plane opening 04 is provided at the lower end of each parabolic reflector 01 at its focal plane position, so that an air hole structure 02 is formed in the parabolic reflector 01. In the present invention, the parabolic reflector 01 is made of a high reflectivity refractory metal such as Mo or Ta; the parabola of the parabolic reflector 01 is composed of a parabola y=x 2 ×c / 2 is formed by rotating around the central axis, c is the parabolic curvature, and the focus position is located at 1 / 2c; the height H of the parabolic reflector 01 is 20-500μm, and the curvature c is 0.05-0.1μm -1 , the diameter d of the focal plane opening 04 is 20-40 μm.

[0050] The reflector substrate 03 is made of refractory metal, and is provided with a plurality of substrate parabolic through holes arranged in an array and respectively matching with a plurality of parabolic reflectors 01; each parabolic reflector 01 is formed by a refractory metal reflective film plated on the inner wall of the corresponding substrate parabolic through hole. In the present invention, the reflector substrate holder 03 is made of HfO2 material.

[0051] like Figure 1 As shown, the multilayer film absorption portion includes a wavelength selective absorption multilayer film and a refractory metal substrate 08 .

[0052] The upper surface of the wavelength selective absorption multilayer film is attached to the focal plane position of all parabolic reflectors 01, that is, attached to the edges of all focal plane openings 04. In the present invention, the wavelength selective absorption multilayer film is a three-layer film structure, consisting of an upper surface layer 05, an intermediate layer 06 and a lower surface layer 07; the upper surface layer 05 is made of a HfO2 material layer with a thickness of 0.1166μm, the intermediate layer 06 is made of a W material layer with a thickness of 0.0348μm, and the lower surface layer 07 is made of a HfO2 material layer with a thickness of 0.03μm.

[0053] The refractory metal substrate 08 is disposed on the lower surface of the wavelength selective absorption multilayer film, and is made of W, Mo or Ta material, with a thickness ranging from 0.5 mm to several millimeters.

[0054] Figure 2 The figure shows the light propagation of parabolic reflectors and wavelength selective multilayer films at different angles; Figure 2 a is a schematic diagram of light propagation at vertical incidence. Figure 2 b is a schematic diagram of light propagation when the incident light angle is small. Figure 2 c is a schematic diagram of light propagation when the incident light angle is large.

[0055] like Figure 2As shown in a, when the incident light is incident vertically, the light is focused by the parabolic reflector 01 onto the surface of the wavelength selective absorption multilayer film located at the center of the focal plane opening 04, so that the light with a wavelength lower than the absorption cutoff wavelength of the wavelength selective absorption multilayer film is absorbed by the wavelength selective absorption multilayer film and the light with a wavelength higher than the absorption cutoff wavelength is reflected, thereby achieving a wavelength selective radiation effect at a small angle and being insensitive to polarization.

[0056] like Figure 2 As shown in b, when the incident light angle is small, part of the incident light is reflected by the parabolic reflector 01 onto the surface of the wavelength selective absorption multilayer film to achieve wavelength selective absorption, while the other part of the light is directly reflected and is not absorbed at all.

[0057] like Figure 2 As shown in c, when the incident angle is large, all the incident light is reflected back by the parabolic reflector 01, thereby achieving the effect that large-angle light is not absorbed, that is, only small-angle thermal radiation exists.

[0058] In summary, the thermal radiator of the present invention focuses the incident light at different angles by the parabolic reflector 01 to the wavelength selective absorption multilayer film part or reflects it back, thereby achieving the effect of large-angle incident light being reflected and small-angle incident light being absorbed; according to Kirchhoff's law of thermal radiation and the reversible theorem of light path, the angle-selective thermal radiation effect of high emission at small normal angles and no emission at large angles is achieved.

[0059] Figure 3 The transmittance results of the parabolic reflector with a curvature c of 0.1μm-1 and a height H of 30μm calculated by lighttools at different incident angles are shown. It can be seen that when the incident light angle is a small angle direction in the normal range, the transmittance reaches 0.9069. The reason why it does not reach 1 is that when the parabolic reflector is hexagonally close-packed, there is a gap in the middle. The gap part becomes a high-reflection part when the coating is tilted. Therefore, the transmittance does not reach 1 at vertical incidence, but is equal to the duty cycle of the circular parabolic micropore. The transmittance of the incident light decreases rapidly with the increase of the incident light angle. When the incident light angle is 30°, the transmittance is only 0.06. When the incident light angle increases to 37.5°, the transmittance drops to 0, and the transmittance remains zero as the angle increases. That is, the incident light greater than 37.5° will be completely reflected by the parabolic reflector without entering the wavelength selective absorption multilayer film and producing no absorption. Thus, the angle is limited to the small normal angle range. The angle selective thermal radiator effect is achieved.

[0060] Figure 4The relationship between the absorptivity and wavelength of the wavelength selective absorption multilayer film (using a three-layer film structure of HfO2 / W / HfO2 with film thicknesses of 0.1166μm, 0.0348μm, and 0.03μm) optimized by the genetic algorithm combined with the transfer matrix algorithm to match the absorption cutoff wavelength of the GaSb battery is shown. It can be seen that the absorptivity of the structure within a wavelength of 1.7μm is between 0.6-0.8, while the absorptivity of wavelengths greater than 1.7μm continues to decrease, and the absorptivity of wavelengths above 2.2μm drops to below 0.2. Compared with the blackbody radiation with no wavelength selection, the multilayer film structure can better match the absorption band gap of the GaSb battery, thereby improving the efficiency of the thermophotovoltaic system.

[0061] <Example>

[0062] like Figure 5 As shown, grayscale lithography is used to control the grayscale level of photoresist exposure to form a parabolic photoresist structure. The topography is then transferred to the HfO2 material by reactive ion beam etching (RIE) to form a curvature c of 0.1 μm. -1 , a reflector substrate 03 with a height H of 30μm, and a refractory metal reflective film of 0.1μm is plated on the reflector substrate 03 by electron beam evaporation oblique coating using Ta as a parabolic reflector 01. Since the parabola cross section is circular, a refractory metal reflective film is formed on the upper surface of the reflector substrate 03 except for the parabolic micropores of the substrate during hexagonal close packing to form a reflective plane 09. When light hits this part, it will maintain high reflection regardless of the incident angle, and the effective parabolic ratio is 0.9069. This part of the metal film limits the maximum absorption rate to only 0.9069 when the incident angle is small. The focal plane opening 04 is located at the focal plane position of the parabolic reflector 01, and its diameter d is 20μm; an air hole structure 02 is formed inside the parabolic reflector 01; an upper surface layer 05 of HfO2 material with a thickness of 0.1166μm, an intermediate layer 06 of W material with a thickness of 0.0348μm, and a lower surface layer 07 of HfO2 material with a thickness of 0.03μm constitute a wavelength selective absorption multilayer film with a three-layer film structure; a refractory metal substrate 08 is formed by electron beam evaporation coating a 1mm W material film on the lower surface of the lower surface layer 07.

[0063] The top view of the hexagonal close-packed Figure 6 As shown by Figure 6 It can be calculated that the effective parabola ratio within a period unit excluding the reflection plane 09 is πR 2 / 4R 2 =0.9069, where R is the radius of the parabolic reflector at the light entrance. In this embodiment, R=24.49 μm.

[0064] Figure 7The calculation results of the absorptivity of this embodiment at wavelengths of 1μm, 1.5μm, 2.0μm, and 2.5μm respectively vary with angle. It can be seen that the absorptivity of this embodiment at 1μm and 1.5μm within the GaSb absorption cutoff wavelength has a high absorptivity, i.e., emissivity, at small angles (0-15°), and when the angle increases to 40°, the absorptivity drops to zero, thereby achieving a small-angle selective polarization-insensitive emission that matches the absorption band of the thermal photovoltaic cell. When the absorptivity at 2μm and 2.5μm above the absorption cutoff wavelength drops to below 0.3 even in the normal direction, as the angle increases, the absorptivity further decreases, thereby achieving radiation suppression in the band that the thermal photovoltaic cell does not absorb, achieving simultaneous selective emission of angle and wavelength, and limiting the emission angle to the cutoff angle range that the thermal photovoltaic cell can receive.

[0065] <Modification 1>

[0066] This modification example 1 is a further improvement of the embodiment. The same symbols are given to the same structures as those in the embodiment, and the same descriptions are omitted.

[0067] like Figure 8 As shown, in this variation 1, the substrate parabolic through holes of the parabolic reflector 01 and the reflector substrate 03 are hexagonal close-packed structures of hexagonal parabolas, so that the parabola is formed by scanning the hexagon of the upper surface with a parabola. The circular upper surface is changed to a hexagon circumscribed to the original circular surface, thereby changing the morphology of the parabolic reflector 01, and the morphology of the focal plane opening 04 of the parabolic reflector 01 is changed to a hexagon. In this way, the effective parabola accounts for 1% when incident vertically, achieving the effect of being able to pass through the parabolic reflector with 100% incident vertically.

[0068] <Modification 2>

[0069] This variant example 2 is a further improvement of the variant example 1. The same symbols are given to the same structures as those in the variant example 1, and the same descriptions are omitted.

[0070] like Fig. 9 As shown, in this second variation, the parabolic reflector 01 and the substrate parabolic through hole of the reflector substrate holder 03 are closely packed structures of triangular parabolas, so that the parabola is formed by a parabola scanning along the triangle of the upper surface. The hexagonal upper surface is changed to a triangle, thereby changing the morphology of the parabolic reflector 01, and the morphology of the focal plane opening 04 of the parabolic reflector 01 is changed to a triangle. In this way, not only the effective parabola ratio reaches 1 at vertical incidence, but also a stronger angle selection effect is achieved. When the angle is 30°, the emissivity reaches 0. Compared with the circular upper surface parabola angle of 37.5° and the hexagonal upper surface parabola angle of 34.5°, the cut-off angle is further reduced.

[0071] <Variation 3>

[0072] This variant example 3 is a further improvement of the embodiment and variant examples 1 and 2. The same symbols are given to the same structures as those in the embodiment, variant example 1 and variant example 2, and the same descriptions are omitted.

[0073] In this third variation, a 0.1 μm thick anti-oxidation film of HfO2 material is deposited on the inner surface of the parabolic reflector 01 by oblique electron beam evaporation to prevent oxidation of the refractory metal Ta reflector under high temperature conditions and reduce the reflectivity of the parabolic reflector.

[0074] In this third variation, the method for preparing a thermal radiator based on a micro parabolic reflector array includes the following steps S1-S6.

[0075] Step S1 , coating a wavelength selective absorption multilayer film on a refractory metal substrate 08 .

[0076] Specifically, a wavelength selective absorption multilayer film can be prepared on the refractory metal substrate 08 by magnetron sputtering, electron beam evaporation or thermal evaporation process;

[0077] In this third variation, an electron beam evaporation process is used to sequentially evaporate a lower surface layer 07 of HfO2 material with a thickness of 0.03 μm, an intermediate layer 06 of W material with a thickness of 0.0348 μm, and an upper surface layer 05 of HfO2 material with a thickness of 0.1166 μm on a refractory metal substrate 08 made of tungsten material with a thickness of 1 mm, thereby forming a wavelength selective absorption multilayer film with a three-layer film structure.

[0078] Step S2, coating a refractory metal layer on the wavelength selective absorption multilayer film as a reflector substrate 03.

[0079] Specifically, an electron beam evaporation process is used to evaporate a 30 μm thick HfO 2 material refractory metal layer on the wavelength selective absorption multilayer film as the reflector substrate 03 .

[0080] Step S3, spin-coating a photoresist layer on the reflector substrate 03, and preparing a plurality of photoresist layer parabolic microholes arranged in an array on the photoresist layer.

[0081] Specifically, a plurality of parabolic microholes arranged in an array may be formed on the photoresist layer through photolithography development or nanoimprint processing.

[0082] In this variant example three, first, the upper surface of the reflector substrate 03 is cleaned by a plasma machine to eliminate surface pollutants and perform surface hydrophilization treatment; then, it is placed on a 150°C heating table for 15 minutes to perform pre-treatment of the reflector substrate 03 before spinning to ensure good adhesion of the photoresist; then, SU-82015 photoresist from SMIC Qiheng Company is selected to spin at a speed of 1500rpm for 1 minute to form a photoresist layer with a thickness of 30μm; and then a grayscale photolithography process is used to form a focal plane opening on the photoresist layer as a triangle, and a parabolic side wall with a curvature c of 0.1μm -1 The parabola of the photoresist layer is scanned around the triangle to form triangular densely packed parabolic micropores in the glue layer; finally, the photoresist layer with the parabolic micropores in the glue layer is post-baked at 200°C for 10 minutes to improve the stability of the photoresist layer and increase the etching ratio of HfO2 to the photoresist.

[0083] Step S4 , transferring the pattern of the plurality of parabolic micro-holes on the photoresist layer to the reflector substrate 03 by etching, thereby forming a plurality of substrate parabolic through holes arranged in an array on the reflector substrate 03 .

[0084] Specifically, reactive ion beam etching is performed using SF6 / Ar etching gas (the ratio of SF6 gas is 75%) to further transfer the pattern of the parabolic microhole array on the photoresist layer to the reflector substrate 03, thereby forming a plurality of substrate parabolic through holes arranged in an array on the reflector substrate 03.

[0085] Step S5 , tilting the semi-finished product obtained in step S4 twice, and coating the inner wall of the parabolic through hole of the substrate with a refractory metal reflective film to form a parabolic reflector 01 .

[0086] Specifically, the semi-finished product obtained in step S4 is first tilted, and tilted electron beam evaporation coating is performed on the reflector substrate 03, and Ta is used to evaporate a refractory metal high-reflection film with a thickness of 200nm on the inner wall of half of the parabolic through hole of the substrate at a deposition rate of 1 nm / s as half of the parabolic reflector 01; then, half of the sample is rotated 180°, and tilted electron beam evaporation coating is performed again, and a refractory metal reflective film with a thickness of 200nm is evaporated on the inner wall of the other half of the parabolic through hole of the substrate as the other half of the parabolic reflector 01.

[0087] Step S6, tilting the semi-finished product obtained in step S5 twice, and coating an anti-oxidation film on the inner surface of the parabolic reflector 01, thereby obtaining a finished heat radiator.

[0088] In the third variation, a 0.1 μm thick HfO2 anti-oxidation film is deposited on the parabolic reflector 01 by two tilted electron beam evaporation processes to prepare a thermal radiator with a triangular closely packed micro parabolic reflector array.

[0089] The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.

[0090] For example, in the above embodiment, the parabolic reflector is prepared by first spin-coating a photoresist layer and then transferring the pattern of the parabolic microhole array on the photoresist layer to the reflector substrate by etching. However, in the present invention, the parabolic reflector can also be directly manufactured on the reflector substrate layer by precision machining methods.

Claims

1. A thermal radiator based on a micro parabolic reflector array, characterized in that: include: It is composed of a micro parabolic reflector array and a multi-layer film absorption part arranged up and down. The micro parabolic reflector array unit comprises a plurality of parabolic reflectors arranged in an array. The lower end of each parabolic reflector is provided with a focal plane opening at the focal plane position. The multilayer film absorption part includes a wavelength selective absorption multilayer film, and the upper surface of the wavelength selective absorption multilayer film is attached to all the edges of the focal plane openings.

2. The heat radiator based on a micro parabolic reflector array according to claim 1, characterized in that: in, The height of the parabolic reflector is 20-500 μm, and the curvature is 0.05-0.1 μm. -1 .

3. The thermal radiator based on a micro parabolic reflector array according to claim 1, characterized in that: in, The micro-parabolic reflector array section further comprises a reflector substrate made of a refractory metal, The reflector substrate is provided with a plurality of substrate parabolic through holes arranged in an array and respectively matching the plurality of parabolic reflectors. Each of the parabolic reflectors is formed by a refractory metal reflective film plated on the inner wall of the corresponding parabolic through hole of the substrate.

4. The heat radiator based on a micro parabolic reflector array according to claim 3, characterized in that: in, The plurality of parabolic reflectors and the plurality of substrate parabolic through holes are a hexagonal close-packed structure of a circular parabola, a hexagonal close-packed structure of a hexagonal parabola, or a triangular close-packed structure of a triangular parabola.

5. The heat radiator based on a micro parabolic reflector array according to claim 3, characterized in that: in, The upper surface of the reflector substrate is plated with a refractory metal reflective film on a portion other than the substrate parabolic through hole.

6. The heat radiator based on a micro parabolic reflector array according to claim 1, characterized in that: in, An anti-oxidation film is provided on the inner surface of the parabolic reflector.

7. The thermal radiator based on a micro parabolic reflector array according to claim 1, characterized in that: in, The wavelength selective absorption multilayer film is a three-layer film structure.

8. The thermal radiator based on a micro parabolic reflector array according to claim 1, characterized in that: in, The multi-layer film absorption portion further includes a refractory metal substrate disposed on the lower surface of the wavelength selective absorption multi-layer film.

9. A method for preparing a thermal radiator based on a micro parabolic reflector array, characterized in that: The following steps are involved: Step S1, coating a wavelength selective absorption multilayer film on a refractory metal substrate; Step S2, coating a refractory metal layer on the wavelength selective absorption multilayer film as a reflector substrate; Step S3, spin coating a photoresist layer on the reflector substrate, and preparing a plurality of parabolic microholes arranged in an array on the photoresist layer; Step S4, transferring the pattern of the plurality of parabolic microholes on the photoresist layer to the reflector substrate by etching, thereby forming a plurality of substrate parabolic through holes arranged in an array on the reflector substrate; Step S5, tilting the semi-finished product obtained in step S4 twice, and plating a refractory metal reflective film on the inner wall of the parabolic through hole of the substrate to form a parabolic reflector; Step S6, tilting the semi-finished product obtained in step S5 twice, and coating an anti-oxidation film on the inner surface of the parabolic reflector, thereby obtaining a finished product of a thermal radiator based on a micro parabolic reflector array.

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