Flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management

Abstract

A flexible multi-band programmable thermal camouflage system compatible with spatial directional emission thermal management belongs to the technical field of thermal camouflage of micro-nano photonic devices. The present invention aims at the problem that the existing thermal camouflage device with adjustable spectral radiation characteristics uses spectral emission to achieve thermal management. It includes a thermal camouflage unit with a lossy material layer as the base layer; an optimization function is constructed to iteratively optimize and calculate the material and thickness of the lower dielectric layer and the two sub-layers and the thickness of the amorphous indium antimony telluride phase change material layer, so that the square control monomer presents the target color, and has a maximum control range of the average directional spectral emissivity within the emission angle range of 0-60° and the infrared bands of 3-5 microns and 8-14 microns, and the average directional spectral emissivity is the largest within the emission angle range of 60°-90° and the 3-14 micron band, and the average directional spectral emissivity is stable during the phase change process of the amorphous indium antimony telluride phase change material layer. The present invention is used for thermal camouflage.

Description

Technical Field

[0001] The invention relates to a flexible multi-band programmable thermal camouflage system compatible with space-directional emission thermal management, and belongs to the technical field of thermal camouflage of micro-nano photonic devices. Background Art

[0002] The infrared radiation characteristics of an object are not only related to the emissivity of the surface of the object, but also to the temperature of the object. With the development of detection technology, static thermal camouflage has been difficult to counter the current advanced multi-band detection technology, making the camouflaged object easily detected by reconnaissance. In recent years, volatile phase change materials such as VO2 and electrochemical materials such as liquid crystal and WO3 have been used in the active regulation of radiation characteristics. However, the current multi-band active thermal camouflage technology using spectral regulation materials usually adopts a wavelength selective thermal emission method, that is, to achieve high emissivity in the non-detection band of 5-8 microns to achieve compatible thermal management. However, due to the dispersion characteristics of active spectral regulation materials, it is difficult to stably maintain the high emission characteristics in the 5-8 micron band when using active optical materials to regulate the emissivity in the detection band, so stable thermal management capabilities cannot be achieved. Summary of the invention

[0003] In view of the problem that the existing method of using spectral emission to achieve thermal management in thermal camouflage devices with adjustable spectral radiation characteristics is unstable, the present invention provides a flexible multi-band programmable thermal camouflage system compatible with spatial directional emission thermal management.

[0004] The present invention provides a flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management, comprising:

[0005] A lossy material layer is used as a base layer, and a plurality of square control monomers are periodically arranged on the base layer to form a rectangular array, thereby obtaining a thermal camouflage unit; each square control monomer is composed of a lower dielectric layer, an amorphous indium antimony telluride phase change material layer and an upper dielectric layer from bottom to top; the upper dielectric layer includes two sub-layers; the materials of the lower dielectric layer and the two sub-layers are germanium or zinc sulfide, respectively;

[0006] An optimization function is constructed to iteratively optimize and calculate the material and thickness of the lower dielectric layer and two sub-layers in each square control monomer and the thickness of the amorphous indium antimony telluride phase change material layer, so that each square control monomer presents a target color, and has a maximum control range of average directional spectral emissivity within the emission angle range of 0-60° and the infrared bands of 3-5 microns and 8-14 microns, and has a maximum average directional spectral emissivity within the emission angle range of 60°-90° and the 3-14 micron band, and the average directional spectral emissivity is stable during the phase change process of the amorphous indium antimony telluride phase change material layer; as a result of the iterative optimization calculation, the Fabry-Perot resonance and Brewster angle effect of the square control monomer are maximized, thereby realizing thermal management of infrared emission in the spatial direction of the square control monomer;

[0007] The amorphous indium antimony telluride phase change material layer determines the area of ​​the crystalline indium antimony telluride phase change interval of the grating structure according to the directional spectral emissivity target value.

[0008] According to the flexible multi-band programmable thermal camouflage system compatible with spatial directional emission thermal management of the present invention, the optimization function includes a color optimization function F1 and an average directional spectral emissivity optimization function F2:

[0009]

[0010] Where x aim is the horizontal coordinate of the square control monomer target color, x is the horizontal coordinate of the square control monomer control color, y aim is the ordinate of the target color of the square-regulated monomer, and y is the ordinate of the regulated color of the square-regulated monomer;

[0011] In the formula is the average directional spectral emissivity of the grating structure crystal phase InSbTe phase transition interval with a wavelength of 3-5 μm and an emission angle range of 0-60°, is the average directional spectral emissivity of the amorphous indium antimony telluride phase change material layer in the non-phase change range when the wavelength is 3-5 microns and the emission angle range is 0-60°, is the average directional spectral emissivity of the amorphous indium antimony telluride phase change material layer in the non-phase change range when the wavelength is 8-14 μm and the emission angle range is 0-60°, is the average directional spectral emissivity of the grating structure crystal phase InSbTe phase transition interval with a wavelength of 8-14 μm and an emission angle range of 0-60°, is the average directional spectral emissivity of the amorphous indium antimony telluride phase change material layer in the non-phase change range when the wavelength is 3-14 μm and the emission angle range is 60°-90°, It is the average directional spectral emissivity of the grating structure crystal phase InSbTe phase change interval when the wavelength is 3-14 microns and the emission angle range is 60°-90°.

[0012] According to the flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management of the present invention, the lossy material layer is a flexible polyvinyl chloride layer, and its infrared transmittance is 0 by selecting the thickness.

[0013] According to the flexible multi-band programmable thermal camouflage system compatible with spatial directional emission thermal management of the present invention, the sum of the directional spectral absorptivity and the directional spectral reflectivity of the square control monomer is 1; according to Kirchhoff's law, the directional spectral absorptivity is the same as the directional spectral emissivity.

[0014] According to the flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management of the present invention, the amorphous indium antimony telluride phase change material layer is heated by a laser direct writing excitation source to extend in the middle section to form a grating structure crystal indium antimony telluride phase change interval; the grating structure crystal indium antimony telluride phase change interval is heated to a melting temperature by laser and then cooled and transformed into a non-phase change interval of the amorphous indium antimony telluride phase change material layer;

[0015] By adjusting the area ratio of the crystalline In2SbTe phase change range of the grating structure in the amorphous In2SbTe phase change material layer, the average directional spectral emissivity of the square control monomer can be continuously controlled between 0-1 within the emission angle range of 0-60° and in the infrared bands of 3-5 microns and 8-14 microns.

[0016] According to the flexible multi-band programmable thermal camouflage system compatible with space direction emission thermal management of the present invention, and Expressed as the average directional spectral emissivity

[0017]

[0018] In the formula is the azimuth angle, ε(λ,θ) is the directional spectral emissivity, λ is the wavelength, θ is the emission angle, h is Planck's constant, c is the speed of light in vacuum, k B is the Boltzmann constant, and T is the temperature of the thermal camouflage unit.

[0019] According to the flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management of the present invention, the area ratio of the grating structure crystalline phase InSbTe phase change interval in the amorphous phase InSbTe phase change material layer is expressed as f:

[0020] f=L cIST / Λ,

[0021] Where L cIST represents the width of the InSbTe phase transition interval of the grating structure crystal phase, and Λ represents the period of the square control monomer.

[0022] According to the flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management of the present invention, the period of the square control monomer is 3 microns.

[0023] According to the flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management of the present invention, the thickness of the flexible polyvinyl chloride layer is at least 5 mm.

[0024] According to the flexible multi-band programmable thermal camouflage system compatible with space-directional emission thermal management of the present invention, the iterative optimization method of the optimization function includes a genetic optimization method and a particle swarm optimization method.

[0025] Beneficial effects of the present invention: Due to the hemispherical emission characteristics of thermal radiation, thermal detection is usually not performed from a larger incident angle (such as an emission angle greater than 60°). Therefore, the system of the present invention achieves stable and large wide-band thermal radiation within a larger emission angle range to perform thermal management by regulating the spatial thermal emission characteristics of the thermal camouflage device, while developing an active thermal camouflage device with an ultra-wide control spectral range and a large range of thermal radiation characteristic changes within a smaller emission angle range to achieve stable and effective thermal management. The present invention can be used for flexible programmable thermal camouflage compatible with spatial directional emission thermal management in the target environment.

[0026] The system of the present invention utilizes Fabry-Perot resonance and Brewster angle effect to achieve regulation of the spatial emission characteristics of thermal radiation, and can maintain high emission characteristics within a wide emission angle range of more than 60° within a wide band of 3-14 microns, thereby achieving the function of stable thermal management. At the same time, by controlling the phase change state of the indium antimony telluride phase change material to control the switching of the Fabry-Perot resonance band, a large-scale regulation of thermal emission of the thermal camouflage device within the infrared dual detection band is achieved; specific visible color characteristics can be achieved by replacing the dielectric layer material; since Fabry-Perot resonance does not require specific materials and structures, through reasonable optimization design, the regulation of visible color characteristics and infrared thermal emission characteristics can be compatible and will not interfere with each other. The thermal camouflage unit can be used for thermal camouflage in complex target environments. The thermal camouflage unit can not only display most of the color characteristics in terms of regulating thermal radiation characteristics, but also ensures a very high regulation range in the infrared detection band at a small emission angle, and its visible band color characteristics and infrared thermal emission characteristics can be independently regulated; in terms of thermal management, the system of the present invention is the first to propose regulating the spatial emission characteristics of thermal radiation, and achieves more effective thermal management through high emission characteristics within a large emission angle range.

[0027] The system of the present invention has a simple structure and is easy to prepare. The device preparation and emission characteristics regulation can be completed by using magnetron sputtering equipment and laser or electrical excitation, which provides a promising method and platform for more effective multi-band thermal camouflage, and provides a reference for the design and application of multi-band programmable thermal camouflage devices for subsequent compatible directional emission thermal management. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the directional spectral emissivity of the thermal camouflage direction compatible with the ideal directional emission thermal management in the flexible multi-band programmable thermal camouflage system compatible with the spatial directional emission thermal management of the present invention, wherein the emission angle θ ranges from 0 to 90°, The range is 0-360°; the bottom layer of the simplified model in the figure is the base layer, and the upper layer is the equivalent layer of the lower dielectric layer, the amorphous indium antimony telluride phase change material layer and the upper dielectric layer;

[0029] Figure 2 Yes Figure 1 Theoretical calculations are performed on the stacked structure in order to demonstrate the importance of substrate selection for achieving compatible spatial directional emission thermal management. The results in the figure are the average directional spectral emissivity of the real and imaginary parts of the refractive index of different substrates with different germanium dielectric layer thicknesses in the 3-14 μm band with an emission angle greater than 60°. The dotted line in the figure represents the real part of the refractive index (n sub ) is equal to the imaginary part (k sub ), the material whose imaginary part is much larger than the real part is a metal material, the material whose imaginary part is smaller than the real part is a weak loss material, the triangle icon is the spectral refractive index of metal silver Ag, and the green circle icon is the spectral refractive index of polyvinyl chloride PVC; from Figure 2 It can be seen that in order to ensure a large average directional spectral emissivity at a large emission angle, a substrate material with weak loss must be selected. The metal materials commonly used in thermal camouflage devices cannot achieve a large average directional spectral emissivity. PVC is a common and easily available weak loss material with good plasticity, so PVC can be selected as the schematic substrate material; where (a) is the thickness of the germanium dielectric layer h Ge =0.25μm, the average directional spectral emissivity of the real and imaginary parts of the different substrate refractive indexes in the 3-14 μm band with an emission angle greater than 60°; (b) is the thickness of the germanium dielectric layer h Ge =0.75 μm, the average directional spectral emissivity of the real and imaginary parts of the different substrate refractive indexes in the 3-14 μm band with an emission angle greater than 60°, (c) is the thickness of the germanium dielectric layer h Ge = Average directional spectral emissivity of the real and imaginary parts of the refractive index of different substrates in the 3-14 micron band with an emission angle greater than 60° at 1.25 μm;

[0030] Figure 3Schematic diagram of the stacked structure of a square control monomer; in the figure, 1 represents the substrate layer, 2 represents the lower dielectric layer, 3 represents the amorphous indium antimony telluride phase change material layer, 4 represents the grating structure crystalline indium antimony telluride phase change interval, and 5 represents the upper dielectric layer;

[0031] Figure 4 It is a schematic diagram of the formation of a grating structure crystalline indium antimony telluride phase change region in the middle section of the amorphous indium antimony telluride phase change material layer;

[0032] Figure 5 It is a simulation result diagram of the spectral emissivity in the vertical direction of the thermal camouflage unit calculated by the transfer matrix method when the indium antimony telluride phase change material layer is completely unchanged and completely changed when the two sub-layers of the upper dielectric layer and the lower dielectric layer are made of germanium; the thickness of each layer is optimized by adopting the genetic optimization method to ensure the maximum control range of the infrared 3-5 micron and 8-14 micron dual-band emissivity, and the total thickness of the upper dielectric layer is determined to be 731 nanometers, the thickness of the amorphous indium antimony telluride phase change material layer is 23 nanometers, and the thickness of the lower dielectric layer is 50 nanometers; in the figure Indicates the change in average directional spectral emissivity in the infrared 3-5 micron band, It represents the change of average directional spectral emissivity in the infrared 8-14 micron band; the red dotted lines in the figure are at wavelengths of 5 microns and 8 microns;

[0033] Figure 6 yes Figure 5 The directional spectral emissivity of the optimized thermal camouflage unit under transverse magnetic polarization (TM polarization) when the amorphous InSbTe phase change material layer is all in the amorphous phase and all in the crystalline phase;

[0034] Figure 7 yes Figure 5 The directional spectral emissivity of the optimized thermal camouflage unit under transverse electric polarization (TE polarization) when the amorphous InSbTe phase change material layer is all in the amorphous phase and all in the crystalline phase;

[0035] Figure 8 yes Figure 5 The optimized thermal camouflage unit shown in the figure changes the area ratio f of the grating structure crystal phase indium antimony telluride phase change interval, corresponding to the polarization average directional spectral emissivity cloud diagram when the emission angle θ is 0 in the 3-5 micron and 8-14 micron bands; the white dotted lines in the figure are the positions of wavelengths of 5 microns and 8 microns;

[0036] Fig. 9 yes Figure 5 The optimized thermal camouflage unit shown in the figure has a polarization-averaged average directional spectral emissivity of 0 at an emission angle θ of 0 in the 3-5 μm and 8-14 μm bands when the IST phase change material layer has a different proportion f. Schematic diagram of It represents the average directional spectral emissivity in the infrared 3-5 micron band. It represents the average directional spectral emissivity in the infrared 8-14 micron band;

[0037] Fig.10 yes Figure 5 The total hemispherical thermal radiation density of the thermal camouflage unit obtained after optimization in the 3-14 micron band is shown; wherein Region 1 is the thermal radiation density of wavelengths of 3-5 microns and 8-14 microns within the emission angle range of 0° to 60°, Region 2 is the thermal radiation density of wavelengths of 5-8 microns within the emission angle range of 0° to 60°, and Region 3 is the thermal radiation density of wavelengths of 3-14 microns above the emission angle of 60°;

[0038] Fig.11 yes Figure 5 The phase change result of the incident light in the cavity formed by the top layer of air / germanium / amorphous indium antimony telluride when the amorphous indium antimony telluride phase change material layer has not changed after the optimization of the thermal camouflage unit shown;

[0039] Fig.12 yes Figure 5 The optimized thermal camouflage unit shown in the figure shows the phase change result of the normally incident incident light in the cavity formed by the bottom amorphous indium antimony telluride / germanium / polyvinyl chloride when the amorphous indium antimony telluride phase change material layer has not changed phase;

[0040] Fig.13 yes Figure 5 The optimized thermal camouflage unit shown in the figure shows the phase change result of the normally incident incident light in the cavity formed by the top layer of air / germanium / crystalline indium antimony telluride after the amorphous indium antimony telluride phase change material layer undergoes a complete phase change;

[0041] Fig.14 yes Figure 5 The optimized thermal camouflage unit shown in the figure shows the phase change result of the normally incident incident light in the cavity formed by the bottom crystalline indium antimony telluride / germanium / polyvinyl chloride after the amorphous indium antimony telluride phase change material layer undergoes a complete phase change;

[0042] Fig.15 The thermal camouflage unit is obtained by using a genetic optimization method. On the basis of ensuring that the thermal camouflage unit has a high average directional spectral emissivity control capability in the 3-5 micron and 8-14 micron bands and is compatible with directional emission thermal management, the thickness of each layer and the material composition of each dielectric layer are changed. The thermal camouflage unit can achieve a visible light band color range without phase change of indium antimony telluride. The star symbol in the figure represents the sample samples Eg1 to Eg3 extracted from the markings.

[0043] Fig.16 yes Fig.15The color range of the thermal camouflage unit in the structure shown in the visible light band after the indium antimony telluride layer has completely changed phase; the red star symbol indicates Fig.15 The color results after phase change corresponding to the example samples Eg1 to Eg3 are marked in the middle;

[0044] Fig.17 yes Fig.15 and Fig.16 The calculation result diagram of the visible light spectrum reflectance of the thermal camouflage unit shown in Example 1 (Eg1) marked in the middle is when the amorphous indium antimony telluride phase change material layer is all in the amorphous phase and all in the crystalline phase under normal incident non-polarized light; the legend in the figure is the coordinate value in the CIE1931 chromaticity diagram when the amorphous indium antimony telluride phase change material layer is all in the amorphous phase and all in the crystalline phase;

[0045] Fig.18 yes Fig.15 and Fig.16 The calculation result diagram of the visible light spectrum reflectance of the thermal camouflage unit shown in Example 2 (Eg2) marked in the middle is a graph of the visible light spectrum reflectance under normal incident non-polarized light when the amorphous indium antimony telluride phase change material layer is all in the amorphous phase and all in the crystalline phase; the legend in the figure is the coordinate value in the CIE1931 chromaticity diagram when the amorphous indium antimony telluride phase change material layer is all in the amorphous phase and all in the crystalline phase;

[0046] Fig.19 yes Fig.15 and Fig.16 The calculation result diagram of the visible light spectrum reflectance of the thermal camouflage unit shown in Example 3 (Eg3) marked in the middle is a graph of the visible light spectrum reflectance under normal incident non-polarized light when the amorphous indium antimony telluride phase change material layer is all in the amorphous phase and all in the crystalline phase; the legend in the figure is the coordinate value in the CIE1931 chromaticity diagram when the amorphous indium antimony telluride phase change material layer is all in the amorphous phase and all in the crystalline phase;

[0047] Fig. 20 yes Fig.15 and Fig.16 The infrared spectral emissivity calculation result diagram of the thermal camouflage unit shown in Example 1 (Eg1) in the middle is in the 3-14 micron ultra-wide band under normal incident non-polarized light when the amorphous indium antimony telluride phase change material layer is all in the amorphous phase and all in the crystalline phase;

[0048] Fig.21 yes Fig.15 and Fig.16 The infrared spectral emissivity calculation result diagram of the thermal camouflage unit shown in Example 2 (Eg2) in the 3-14 micron ultra-wide band under normal incident non-polarized light when the amorphous indium antimony telluride phase change material layer is all amorphous and all crystalline;

[0049] Fig. 22 yes Fig.15 and Fig.16The infrared spectral emissivity calculation result diagram of the thermal camouflage unit shown in Example 3 (Eg3) in the 3-14 micron ultra-wide band under normal incident non-polarized light when the amorphous indium antimony telluride phase change material layer is all amorphous and all crystalline;

[0050] Fig.23 yes Fig.15 and Fig.16 The directional spectral emissivity ε(λ) cloud diagram of the thermal camouflage unit shown in Example 1 (Eg1) in the middle is in the 3-14 micron band under transverse magnetic polarization (TM polarization) at different emission angles when the amorphous indium antimony telluride phase change material layer is all amorphous and all amorphous;

[0051] Fig.24 yes Fig.15 and Fig.16 The directional spectral emissivity ε(λ) cloud diagram of the thermal camouflage unit shown in Example 1 (Eg1) in the middle is in the 3-14 micron band under transverse electric polarization (TE polarization) at different emission angles when the amorphous indium antimony telluride phase change material layer is all amorphous and all amorphous;

[0052] Fig.25 yes Fig.15 and Fig.16 The average directional spectral emissivity of the thermal camouflage unit shown in Example 1 (Eg1) when adjusting the area ratio f of the grating structure crystal phase indium antimony telluride phase change interval is the average polarization average in the 3-5 micron and 8-14 micron bands when the emission angle θ is 0 Schematic diagram of

[0053] Fig.26 Yes Fig.15 and Fig.16 The example 1-3 marked in the figure is a schematic diagram of a programmable thermal camouflage device, which forms a visible band color camouflage through programmable arrangement;

[0054] Fig. 27 Yes Fig.25 The area ratio f of the crystalline indium antimony telluride phase change interval in each color block is modulated to achieve on-demand customization of the thermal radiation characteristics between different color blocks, thereby realizing a programmable thermal camouflage device schematic for the infrared 3-5 micron and 8-14 micron bands. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0057] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0058] Specific implementation method 1. Combination Figures 1 to 4 As shown, the present invention provides a flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management, comprising:

[0059] A lossy material layer is used as a base layer, and a plurality of square control monomers are periodically arranged on the base layer to form a rectangular array, thereby obtaining a thermal camouflage unit; each square control monomer is composed of a lower dielectric layer, an amorphous indium antimony telluride phase change material layer and an upper dielectric layer from bottom to top; the upper dielectric layer includes two sub-layers; the materials of the lower dielectric layer and the two sub-layers are germanium or zinc sulfide, respectively;

[0060] An optimization function is constructed to iteratively optimize and calculate the material and thickness of the lower dielectric layer and two sub-layers in each square control monomer and the thickness of the amorphous indium antimony telluride phase change material layer, so that each square control monomer presents a target color, and has a maximum control range of average directional spectral emissivity within the emission angle range of 0-60° and the infrared bands of 3-5 microns and 8-14 microns, and has a maximum average directional spectral emissivity within the emission angle range of 60°-90° and the 3-14 micron band, and the average directional spectral emissivity is stable during the phase change process of the amorphous indium antimony telluride phase change material layer; as a result of the iterative optimization calculation, the Fabry-Perot resonance and Brewster angle effect of the square control monomer are maximized, thereby realizing thermal management of infrared emission in the spatial direction of the square control monomer;

[0061] For each square control monomer, the amorphous indium antimony telluride phase change material layer determines the area of ​​the crystalline indium antimony telluride phase change interval of the grating structure according to the directional spectral emissivity target value.

[0062] This embodiment aims to address the problems that existing multi-band radiation thermal camouflage devices lack the ability to actively programmable thermal radiation to adapt to complex and variable environments, and lack effective and compatible thermal management methods. From the perspective of regulating the space emission characteristics of thermal radiation, compatible space directional emission thermal management is achieved based on indium antimony telluride phase change materials.

[0063] In this embodiment, by constructing an optimization function, the material and thickness of the corresponding layer in the square control monomer are determined to reflect the specific target color and infrared spectral emissivity; the infrared spectral emissivity can be controlled by changing the area ratio of the grating structure crystal phase change interval in the periodic structure according to the required target value; due to the combined effect of Fabry-Perot resonance and Brewster angle effect, the thermal camouflage unit can achieve high thermal emissivity at a large angle within an ultra-wide band of 3-14 microns at an emission angle of 60° to 90°, realizing spatial directional emission thermal management.

[0064] The iterative optimization method of the optimization function in this embodiment can adopt a common intelligent optimization method. The lower dielectric layer, the amorphous indium antimony telluride phase change material layer and the upper dielectric layer are all prepared on the lossy material layer by magnetron sputtering in sequence.

[0065] Furthermore, the optimization function includes a color optimization function F1 and an average directional spectral emissivity optimization function F2:

[0066]

[0067] Where x aim is the horizontal coordinate of the square control monomer target color, x is the horizontal coordinate of the square control monomer control color, y aim is the ordinate of the target color of the square-regulated monomer, and y is the ordinate of the regulated color of the square-regulated monomer;

[0068] In the formula is the average directional spectral emissivity of the grating structure crystal phase InSbTe phase transition interval with a wavelength of 3-5 μm and an emission angle range of 0-60°, is the average directional spectral emissivity of the amorphous indium antimony telluride phase change material layer in the non-phase change range when the wavelength is 3-5 microns and the emission angle range is 0-60°, is the average directional spectral emissivity of the amorphous indium antimony telluride phase change material layer in the non-phase change range when the wavelength is 8-14 μm and the emission angle range is 0-60°, is the average directional spectral emissivity of the grating structure crystal phase InSbTe phase transition interval with a wavelength of 8-14 μm and an emission angle range of 0-60°, is the average directional spectral emissivity of the amorphous indium antimony telluride phase change material layer in the non-phase change range when the wavelength is 3-14 μm and the emission angle range is 60°-90°, It is the average directional spectral emissivity of the grating structure crystal phase InSbTe phase change interval when the wavelength is 3-14 microns and the emission angle range is 60°-90°.

[0069] As an example, the lossy material layer is a flexible polyvinyl chloride layer, and its infrared transmittance is 0 by selecting the thickness.

[0070] In this embodiment, the transmittance of the square control monomer in the infrared band of 3-14 microns is 0, and the sum of the directional spectral absorptivity and the directional spectral reflectivity of the square control monomer is 1; according to Kirchhoff's law, the directional spectral absorptivity is the same as the directional spectral emissivity.

[0071] Furthermore, the amorphous indium antimony telluride phase change material layer is heated by a laser direct writing excitation source and extended in the middle section to form a grating structure crystal indium antimony telluride phase change interval; the grating structure crystal indium antimony telluride phase change interval is heated to a melting temperature by laser and then cooled and transformed into a non-phase change interval of the amorphous indium antimony telluride phase change material layer;

[0072] By adjusting the area ratio of the crystalline In2SbTe phase change range of the grating structure in the amorphous In2SbTe phase change material layer, the average directional spectral emissivity of the square control monomer can be continuously controlled between 0-1 within the emission angle range of 0-60° and in the infrared bands of 3-5 microns and 8-14 microns.

[0073] The wavelength range of incident light of the square control monomer is 0.36-0.83 microns in the visible band, 3-5 microns and 8-14 microns in the infrared band, and the emission angle range of infrared emission control is 0-60°.

[0074] By rationally designing the thickness of each layer and selecting the materials, the thermal camouflage unit can achieve high thermal emissivity at a wide band of 3-14 microns at an emission angle of 60° to 90°, and realize the thermal management of spatial directional emission. At the same time, the high emission characteristics of the wide band in this large emission angle range will not change with the emissivity control process at small angles.

[0075] When the flexible programmable thermal camouflage device is applied in this embodiment, the control steps include:

[0076] Step 1: Since the lossy material layer has weak loss characteristics in the infrared band, the thermal emissivity of a sufficiently thick lossy material layer in hemispherical space can be considered to be close to that of a black body; based on the goal of wide-band highly directional thermal radiation within a spatial emission angle of more than 60°, by reasonably optimizing the material and thickness of each sub-layer of the lower dielectric layer and the upper dielectric layer and the thickness of the amorphous indium antimony telluride phase change material layer, Fabry-Perot resonance and Brewster angle effect are stimulated within a large emission angle to achieve compatibility with space emission thermal management functions.

[0077] Step 2: A multi-band thermal camouflage device is formed by combining multiple programmable thermal camouflage units; the material and thickness of each sub-layer of the lower dielectric layer and the upper dielectric layer and the thickness of the amorphous indium antimony telluride phase change material layer are set for each programmable thermal camouflage unit according to the thermal camouflage target color and the maximum spectral emissivity control range within the infrared bands of 3-5 microns and 8-14 microns within the emission angle range of less than 60°;

[0078] Step three, according to the infrared thermal radiation target characteristics, adjust the area ratio of the grating structure crystal phase indium antimony telluride phase change interval in each programmable thermal camouflage unit, so that the normalized infrared thermal radiation intensity of each programmable thermal camouflage unit in the infrared bands of 3-5 microns and 8-14 microns within the emission angle range of less than 60° approaches the target value, thereby realizing the camouflage of multi-band thermal camouflage devices.

[0079] The calculation method of normalized infrared thermal radiation intensity is:

[0080]

[0081] Where I norm is the normalized radiation intensity of each thermal camouflage unit, I min The minimum radiation intensity of all thermal camouflage units; I max is the maximum radiation intensity of all thermal camouflage units; I is the radiation intensity of each thermal camouflage unit:

[0082]

[0083] A plurality of thermal camouflage units are combined to form a visible-infrared multi-band thermal camouflage device; the material and thickness of the lower dielectric layer and the upper dielectric layer sublayer in each programmable thermal color camouflage unit and the thickness of the amorphous indium antimony telluride phase change material layer are set according to the target: (1) target color characteristics; (2) having the maximum spectral emissivity control range in the infrared bands of 3-5 microns and 8-14 microns within a small emission angle range; and (3) having a high and stable wide-spectrum directional emissivity within a directional angle range greater than 60°, so that different units can reflect different color characteristics as needed in the visible band and achieve high thermal radiation characteristics at a large emission angle, thereby realizing programmable color camouflage and directional emission thermal management in the visible band.

[0084] According to the target value of infrared thermal radiation characteristics, the area ratio of the grating structure crystal phase indium antimony telluride phase change range in each programmable thermal emission controller is adjusted, so that the spectral emissivity of each programmable thermal camouflage unit in the infrared bands of 3-5 microns and 8-14 microns approaches the target value, thereby realizing programmable thermal radiation camouflage in the infrared band.

[0085] Since infrared detector imaging will normalize the received thermal radiation density to the maximum and minimum values, the normalized thermal emission characteristics of different color blocks can be controlled on demand by adjusting the area ratio f of the grating structure crystalline phase Indium Antimony Telluride phase change interval, heating the amorphous Indium Antimony Telluride phase change material layer at the corresponding position to transform it into the grating structure crystalline phase Indium Antimony Telluride phase change interval, or reheating the grating structure crystalline phase Indium Antimony Telluride phase change interval and then cooling it, thereby achieving camouflage with programmable infrared thermal emission characteristics.

[0086] The spatial directional emission thermal management characteristics are expressed by the average spectral directional thermal emissivity of the device with a directional angle of more than 60°:

[0087] Will and Expressed as the average directional spectral emissivity

[0088]

[0089] In the formula is the azimuth angle, ε(λ,θ) is the directional spectral emissivity, λ is the wavelength, θ is the emission angle, h is Planck's constant, c is the speed of light in vacuum, k B is the Boltzmann constant, and T is the temperature of the thermal camouflage unit.

[0090] For each square control monomer, according to the infrared thermal radiation target characteristics at the corresponding position, the area ratio of the grating structure's crystalline Indium Antimony Telluride phase change range relative to the amorphous Indium Antimony Telluride phase change material layer can be inverted and determined through genetic optimization and other methods.

[0091] The area ratio of the grating structure crystalline phase InSbTe phase change region in the amorphous phase InSbTe phase change material layer is expressed as f:

[0092] f=L cIST / Λ,

[0093] Where L cIST represents the width of the InSbTe phase transition interval of the grating structure crystal phase, and Λ represents the period of the square control monomer.

[0094] The optimization design method for the thermal camouflage unit is to place the square control unit according to the corresponding CIE1931 chromaticity x aim y aimThe three goals of achieving maximum emissivity control capability in the mid-infrared 3-5 microns and far-infrared 8-14 microns within a small emission angle range and high-stable thermal emissivity at a large angle in the ultra-wide band of 3-14 microns in the emission angle range of 60° to 90° are achieved through the reverse optimization design of the thickness of each layer and the selection of the composition materials of each dielectric layer through the genetic optimization algorithm. This enables the thermal camouflage unit to have the desired color characteristics while achieving the maximum range of thermal emission control of infrared 3-5 microns and 8-14 microns in a small emission angle range and being compatible with excellent directional emission thermal management in a large emission angle range.

[0095] In this embodiment, the target color of the square control monomer is represented by the coordinates in the CIE1931 xy colorimetric system:

[0096]

[0097] Where x aim is the horizontal coordinate of the thermal camouflage target color in the CIE1931xy colorimetric system, y aim is the ordinate of the thermal camouflage target color in the CIE1931xy colorimetric system; X is the stimulus value of red among the three primary colors, Y is the stimulus value of green among the three primary colors, and Z is the stimulus value of blue among the three primary colors;

[0098]

[0099] Where λ is the incident light wavelength of the square control monomer, S(λ) is the standard spectral radiation energy distribution of the D65 light source, and R(λ) is the spectral reflectivity of the thermal camouflage environment background or thermal camouflage object in the visible band; and are the standard matching functions for the three primary color stimulus values ​​respectively.

[0100] As an example, the period of the square control monomer is 3 micrometers. The material of the lower dielectric layer is one of germanium or zinc sulfide.

[0101] The infrared detection band (3-5 microns and 8-14 microns) is one of the most important atmospheric windows for infrared detection, thermal camouflage and thermal control. Non-volatile phase change materials show stable performance and huge optical contrast between amorphous and crystalline states, reflecting great potential for integration into infrared optical modulation platforms. Indium antimony telluride, as a non-volatile phase change material, can show metal-like properties with huge negative dielectric constants in the entire infrared region in the crystalline phase. In the amorphous phase, it acts as a lossless dielectric medium in the infrared region, but its optical properties in the visible band can remain almost unchanged before and after the change, and it can achieve non-volatile local phase change through laser or electrical excitation, laying the foundation for the development of continuously controlled, programmable, and large-scale mid-infrared emissivity control devices. The use of a large emission angle range that is not commonly used in thermal detection for thermal management provides a new way to manage the thermal performance of multifunctional thermal camouflage devices by regulating the spatial emission characteristics of thermal radiation.

[0102] As an example, the thickness of the flexible polyvinyl chloride layer needs to be thick enough, much larger than its skin depth in the mid-infrared band, at least 5 mm, to ensure that the infrared transmittance of the square control monomer is 0 in the infrared band of 3-14 microns. Since the polyvinyl chloride layer is a flexible material, the device has good plasticity.

[0103] As examples, iterative optimization methods for optimizing functions include genetic optimization methods and particle swarm optimization methods. Specific embodiment one:

[0105] Combination Figure 5 As shown, when only the maximum adjustable range of the emissivity in the infrared dual detection bands and the compatible directional emission thermal management characteristics are considered, the materials of each layer in the lower dielectric layer and the upper dielectric layer can be selected as germanium. Through the genetic algorithm optimization design, the thickness of the lower dielectric layer is 50 nanometers, the total thickness of the upper dielectric layer is 731 nanometers, and the thickness of the amorphous indium antimony telluride phase change material layer is 23 nanometers. Through the transfer matrix method simulation calculation verification, under this structural parameter, when the amorphous indium antimony telluride phase change material layer changes from a fully amorphous phase to a fully crystalline phase, when each square control monomer obtains the spectral emissivity in the dual infrared bands of 3-5 microns and 8-14 microns The control capability is within the range of 0.3 to 0.8, the average emissivity control amplitude of 3-5 microns in the mid-infrared detection band is 0.343, and the average emissivity control amplitude of 8-14 microns in the far-infrared detection band is 0.402. It has a sufficiently large spectral emissivity amplitude control capability and realizes the emissivity switching in the dual infrared detection bands.

[0106] Combination Figure 6 and Figure 7As shown, through transfer matrix method simulation calculation verification, under transverse electric (TM) polarization and transverse magnetic (TE) polarization, each square control monomer can realize the switching of emissivity within the 3-5 micron and 8-14 micron bands within the emission angle of 0 to 60 degrees by controlling the phase change state of the amorphous indium antimony telluride phase change material layer. Due to the polarization selectivity of the Brewster angle effect (which can only exist under TM polarization) and the phase matching condition of Fabry-Perot resonance, a spectral emissivity close to 1 is achieved within the emission angle range of 60° to 90° under TM polarization, realizing the function of compatible directional emission thermal management.

[0107] Combination Figure 8 and Fig. 9 As shown, in this embodiment, when laser or electric excitation is applied to the amorphous indium antimony telluride phase change material layer, a grating-shaped crystalline indium antimony telluride phase change interval can be generated in the amorphous indium antimony telluride phase change material layer, and by controlling the size f of the phase change region, the average emissivity of the square control monomer in the mid-infrared 3-5 micron band can be continuously controlled from 0.382 (the indium antimony telluride layer is all amorphous) to 0.725 (the indium antimony telluride layer is all crystalline), and the average emissivity of the far-infrared 8-14 micron band of the thermal camouflage unit can be continuously controlled from 0.365 (the indium antimony telluride layer is all amorphous) to 0.767 (the indium antimony telluride layer is all crystalline). At the same time, by using high-power laser or electric excitation to heat the crystalline indium antimony telluride to a molten state and then rapidly cooling it, the crystalline indium antimony telluride can be converted back to the amorphous indium antimony telluride, realizing reversible control.

[0108] Combination Fig.10 As shown, in this embodiment, Region 1 represents the thermal radiation intensity of the thermal camouflage unit in the 3-5 micron and 8-14 micron bands with a directional angle of 0 to 60 degrees, Region 2 represents the thermal radiation intensity of the thermal camouflage unit in the 5-8 micron band with a directional angle of 0 to 60 degrees, and Region 3 represents the thermal radiation intensity of the thermal camouflage unit in the 3-14 micron band with a directional angle of more than 60 degrees; by controlling the phase change region proportion size f, the emissivity of the thermal camouflage unit in the 3-5 micron band and the 8-14 micron band can be improved, thereby increasing the thermal radiation intensity; and the 5-8 micron band is a commonly used spectral thermal management band. Due to the spectral characteristics of the material dielectric function, the spectral emissivity in the band will be reduced during the thermal radiation regulation process, resulting in a weakening of the thermal radiation intensity, which is also the defect of the existing spectral thermal management method; and the high thermal radiation characteristics within the spatial range of the emission angle greater than 60 degrees will not emit changes during the thermal radiation regulation process, thereby improving the overall thermal radiation heat dissipation power of the device, and providing a new way to better achieve thermal management of thermal camouflage devices.

[0109] In this embodiment, when the thermal camouflage device compatible with directional emission thermal management is used for infrared programmable thermal camouflage, each thermal camouflage unit calculates the phase change proportion f of the square control monomer within it according to the target value of the thermal radiation characteristics of the corresponding position, thereby reflecting the required specific thermal radiation characteristics and realizing programmable thermal camouflage in a complex camouflage environment. Using laser and electrical excitation, unit structures with different phase change ranges can be prepared in different regions within a large area, and the mid-infrared emissivity in different regions can be programmably customized and regulated according to actual environmental requirements.

[0110] Combination Figures 11 to 14 The working process and principle of the present invention in the regulation of infrared thermal radiation characteristics are described as follows: the multi-layer stacked structure forms two nanocavities of air / germanium / indium antimony telluride and indium antimony telluride / germanium / polyvinyl chloride. When the net phase shift of the incident light in the cavity is an integer multiple of 2π, it can stimulate the generation of Fabry-Perot resonance to increase the absorption in the cavity. Before the phase change, the phase shifts in the two nanocavities of air / germanium / amorphous indium antimony telluride and air / germanium / amorphous indium antimony telluride are both around 3.235 microns and 6.418 microns, which are integer multiples of 2π, and are extremely close to the calculated peak wavelengths of the emissivity of the device before the phase change, 3.219 microns and 6.43 microns. Therefore, it can be considered that Fabry-Perot resonance occurs in the two cavities, so the device as a whole exhibits weak infrared spectral emission characteristics at 3-5 microns and 8-14 microns, and achieves strong infrared spectral emission characteristics at 5-8 microns. After the phase change, the phase shift results show that the net phase shift in the top-layer air / germanium / crystalline indium antimony telluride nanocavity is 4.278 microns and 12.807 microns, which is an integer multiple of 2π, and is extremely close to the calculated peak wavelength of the device's emissivity before the phase change of 4.266 microns and 12.82 microns. Therefore, it can be considered that Fabry-Perot resonance occurs in the cavity of the top layer, so the device as a whole shows strong infrared spectral emission characteristics at 3-5 microns and 8-14 microns, achieving the switching of emissivity. At the same time, the phase changes, and the emission resonance peak in the 5-8 micron band will disappear during the regulation process. Therefore, the thermal management of the adjustable thermal emission device using the 3-5 micron band alone has great limitations and cannot achieve stable and good thermal management.

[0111] Since Fabry-Perot resonance can be excited only by satisfying the phase matching condition in a transparent medium cavity, no specific material is required. Therefore, by properly selecting materials and optimizing thickness, the color of the required visible band can be achieved while ensuring the infrared directional spectral emissivity characteristics. Fig.15 and Fig.16As shown, in the present invention, by optimizing the design to change the thickness of each layer and the material composition of the lower dielectric layer and the upper dielectric layer, the obtained device can reflect almost all visible light colors when the amorphous indium antimony telluride phase change material layer does not change or changes completely. Since the optical properties of indium antimony telluride in the visible band change little and the thickness is thin, the visible color characteristics before and after the phase change do not change.

[0112] Figures 17 to 19 The visible band spectral reflectance R(λ) of three schematic devices with different visible color characteristics and their coordinates and color characteristics in the CIE1931 coordinate diagram are shown. Figure 20 to Figure 22 for Figures 17 to 19 The calculation results of the infrared spectral thermal emission characteristics of the device shown in the figure before and after the phase transition of the amorphous InSbTe layer show good control potential in the infrared detection band.

[0113] Combination Fig.23 and Fig.24 In this embodiment, it is demonstrated that the example device 1 can still achieve a relatively high directional thermal emission characteristic within the range of an emission angle greater than 60°, thereby realizing the function of space emission thermal management. At the same time, by utilizing the phase change characteristics of the amorphous indium antimony telluride phase change material layer, the spectral emissivity switching within the 3-5 micron and 8-14 micron bands is achieved within the range of an emission angle less than 60°.

[0114] In summary, the thermal camouflage unit in this embodiment can achieve high directional thermal emissivity at a large angle within an ultra-wide band of 3-14 microns at an emission angle greater than 60° by optimizing the material composition of the upper dielectric layer and the lower dielectric layer and the thickness of each layer. Combined with the non-volatile phase change characteristics and local phase change characteristics of indium antimony telluride phase change materials, the thermal emissivity can be continuously adjusted within the infrared detection bands of 3-5 microns and 8-14 microns at an emission angle less than 60°, laying the foundation for the realization of flexible and programmable thermal camouflage with compatible directional emission thermal management.

[0115] This embodiment first optimizes the thickness of each layer and the material selection of the dielectric layer of multiple thermal camouflage units based on indium antimony telluride phase change materials with compatible directional emission thermal management, and ensures that the multiple devices have greater controllability and compatible directional emission thermal management in the infrared detection band of 3-5 microns and 8-14 microns, so that the multiple devices can reflect different color characteristics as needed in the visible band. Then, the obtained thermal camouflage units are used as color blocks of thermal camouflage equipment, and are arranged and combined into camouflage devices with visible color camouflage characteristics. Fig.15 and Fig.16 As an example, the structures of Examples 1 to 3 in the example above can be arranged as required to form the following Fig.25 The HIT pattern shown can also be arranged into a more confusing pattern as required.

[0116] Through Fig.25 By adjusting the proportion f of the crystalline indium antimony telluride phase change region in each color block, different color blocks can exhibit different thermal radiation characteristics. By design, when the proportion f of the phase change region of Example 1 and Example 2 units in the first "H" letter area is 1 and 0 respectively, the proportion f of the phase change region of Example 2 and Example 3 units in the second "I" letter area is 0.7 and 0.3 respectively, and the proportion f of the phase change region of Example 1 and Example 3 units in the third "T" letter area is 0 and 1 respectively, Fig.25 The normalized thermal radiation density images of the thermal camouflage device in the 3-5 micron and 8-14 micron detectors are shown as follows Fig.26 and Fig. 27 As shown, a more confusing infrared image can be achieved by combining more units and changing the phase change area proportion f of different color blocks.

[0117] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. A flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management, characterized in that: A lossy material layer is used as a base layer, and a plurality of square control monomers are periodically arranged on the base layer to form a rectangular array, thereby obtaining a thermal camouflage unit; each square control monomer is composed of a lower dielectric layer, an amorphous indium antimony telluride phase change material layer and an upper dielectric layer from bottom to top; the upper dielectric layer includes two sub-layers; the materials of the lower dielectric layer and the two sub-layers are germanium or zinc sulfide, respectively; An optimization function is constructed to iteratively optimize and calculate the material and thickness of the lower dielectric layer and two sub-layers in each square control monomer and the thickness of the amorphous indium antimony telluride phase change material layer, so that each square control monomer presents a target color, and has a maximum control range of average directional spectral emissivity within the emission angle range of 0-60° and the infrared bands of 3-5 microns and 8-14 microns, and has a maximum average directional spectral emissivity within the emission angle range of 60°-90° and the 3-14 micron band, and the average directional spectral emissivity is stable during the phase change process of the amorphous indium antimony telluride phase change material layer; as a result of the iterative optimization calculation, the Fabry-Perot resonance and Brewster angle effect of the square control monomer are maximized, thereby realizing thermal management of infrared emission in the spatial direction of the square control monomer; The amorphous indium antimony telluride phase change material layer determines the area of ​​the crystalline indium antimony telluride phase change interval of the grating structure according to the directional spectral emissivity target value; The amorphous indium antimony telluride phase change material layer is heated by a laser direct writing excitation source and extended in the middle section to form a grating structure crystal indium antimony telluride phase change interval; the grating structure crystal indium antimony telluride phase change interval is heated to a melting temperature by laser and then cooled and transformed into a non-phase change interval of the amorphous indium antimony telluride phase change material layer; By adjusting the area ratio of the crystalline In2SbTe phase change range of the grating structure in the amorphous In2SbTe phase change material layer, the average directional spectral emissivity of the square control monomer can be continuously controlled between 0-1 within the emission angle range of 0-60° and in the infrared bands of 3-5 microns and 8-14 microns.

2. The flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management according to claim 1 is characterized in that: The optimization function includes the color optimization function F1 and the average directional spectral emissivity optimization function F2: Where x aim is the horizontal coordinate of the square control monomer target color, x is the horizontal coordinate of the square control monomer control color, y aim is the ordinate of the target color of the square-regulated monomer, and y is the ordinate of the regulated color of the square-regulated monomer; In the formula is the average directional spectral emissivity of the grating structure crystal phase InSbTe phase transition interval with a wavelength of 3-5 μm and an emission angle range of 0-60°, is the average directional spectral emissivity of the amorphous indium antimony telluride phase change material layer in the non-phase change range when the wavelength is 3-5 microns and the emission angle range is 0-60°, is the average directional spectral emissivity of the amorphous indium antimony telluride phase change material layer in the non-phase change range when the wavelength is 8-14 μm and the emission angle range is 0-60°, is the average directional spectral emissivity of the grating structure crystal phase InSbTe phase transition interval with a wavelength of 8-14 μm and an emission angle range of 0-60°, is the average directional spectral emissivity of the amorphous indium antimony telluride phase change material layer in the non-phase change range when the wavelength is 3-14 μm and the emission angle range is 60°-90°, It is the average directional spectral emissivity of the grating structure crystal phase InSbTe phase change interval when the wavelength is 3-14 microns and the emission angle range is 60°-90°.

3. The flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management according to claim 2 is characterized in that: The lossy material layer is a flexible polyvinyl chloride layer, and its infrared transmittance is 0 by selecting the thickness.

4. The flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management according to claim 3 is characterized in that: The sum of the directional spectral absorptivity and the directional spectral reflectivity of the square control monomer is 1; according to Kirchhoff's law, the directional spectral absorptivity is the same as the directional spectral emissivity.

5. The flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management according to claim 4 is characterized in that: Will and Expressed as the average directional spectral emissivity In the formula is the azimuth angle, ε(λ,θ) is the directional spectral emissivity, λ is the wavelength, θ is the emission angle, h is Planck's constant, c is the speed of light in vacuum, k B is the Boltzmann constant, and T is the temperature of the thermal camouflage unit.

6. The flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management according to claim 5 is characterized in that: The area ratio of the grating structure crystalline phase InSbTe phase change region in the amorphous phase InSbTe phase change material layer is expressed as f: f=L cIST / L, Where L cIST represents the width of the InSbTe phase transition interval of the grating structure crystal phase, and Λ represents the period of the square control monomer.

7. The flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management according to claim 6 is characterized in that: The period of the square regulatory monomer is 3 microns.

8. The flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management according to claim 3 is characterized in that: The thickness of the flexible polyvinyl chloride layer is at least 5 mm.

9. The flexible multi-band programmable thermal camouflage system compatible with space-direction emission thermal management according to claim 1 is characterized in that: Iterative optimization methods for optimization functions include genetic optimization methods and particle swarm optimization methods.

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