阅读说明：本技术 一种多波段兼容散热功能性红外隐身材料 (Multi-band compatible heat dissipation functional infrared stealth material ) 是由 *** 朱桓正 仇旻 于 2019-10-10 设计创作，主要内容包括：本发明公开了一种多波段兼容散热功能性红外隐身材料,包括红外与可见光波段的光学薄膜结构和适用于微波的金属-损耗导电层-金属的超表面结构,其满足：3-5μm波段的反射率在0.8以上；8-14μm波段的反射率在0.8以上；10.6μm波段的吸收率在0.8以上；5-8μm波段的吸收率在0.5以上；微波X波段的吸收率在0.8以上。本发明利用红外DBR的高反射特性实现了红外大气窗口波段的隐身并利用表层减反膜实现了可变的颜色。实现了在X波段的高吸收。同时微波超表面结构具有较小的厚度与单位面积重量,可以有效的避免由于隐身材料带来的额外重量负担。(The invention discloses a multiband compatible heat dissipation functional infrared stealth material, which comprises an optical thin film structure of infrared and visible light bands and a metal-loss conducting layer-metal super surface structure suitable for microwaves, and meets the following requirements: the reflectivity of the wave band of 3-5 mu m is more than 0.8; the reflectivity of the wave band of 8-14 μm is above 0.8; the absorptivity of the 10.6 mu m wave band is more than 0.8; the absorptivity of the wave band of 5-8 μm is above 0.5; the absorptivity of microwave X wave band is above 0.8. The invention realizes the stealth of the infrared atmospheric window wave band by utilizing the high reflection characteristic of the infrared DBR and realizes variable color by utilizing the surface antireflection film. High absorption in the X band is achieved. Meanwhile, the microwave super-surface structure has smaller thickness and unit area weight, and can effectively avoid extra weight burden caused by stealth materials.)

1. A multiband compatible heat dissipation functional infrared stealth material is characterized by comprising an optical thin film structure of infrared and visible light bands and a metal-loss conducting layer-metal super surface structure suitable for microwaves, and meeting the following requirements:

the reflectivity of light with the wavelength of 3-5 mu m wave band is more than 0.8;

the reflectivity of light with the wavelength of 8-14 mu m wave band is more than 0.8;

the absorptivity to light with wavelength of 10.6 μm wave band is above 0.8;

the absorptivity to light with wavelength of 5-8 μm wave band is above 0.5;

the absorptivity to microwave X wave band is above 0.8.

2. The multi-band compatible heat dissipating functional infrared stealth material of claim 1, wherein the infrared and visible band optical thin film structure is comprised of a substrate, an infrared band film layer and a visible band film layer; the infrared band film layer consists of high-refractive-index material film layers and low-refractive-index material film layers which are sequentially and alternately deposited on the substrate, and the innermost layer and the outermost layer are high-refractive-index material film layers; the visible light wave band film layer is a low refractive index material film layer deposited on the top surface of the infrared light wave band film layer, and the thickness of the film layer is less than lambda₁/(4n₁) Wherein n is₁Is the refractive index, λ, of the material of the film₁Is 3-14 microns.

3. The multiband compatible heat dissipating functional infrared stealth material of claim 2, wherein the high refractive index material is germanium; the low refractive index material is selected from one or more of zinc sulfide, zinc selenide, barium fluoride and calcium fluoride.

4. The multiband compatible heat dissipating functional infrared stealth material of claim 2, wherein the high refractive index material is germanium and the low refractive index material is zinc sulfide.

5. The multiband compatible heat dissipation functional infrared stealth material of claim 2, wherein the total number of the high and low refractive index material thin film layers is 11-15, and at least one of the high refractive index material thin film layers has a layer thickness less than λ₂/(4n₂) Wherein n is₂Is the refractive index, λ, of the material of the film₂Is 8-14 microns.

6. The multiband compatible heat dissipation functional infrared stealth material of claim 4, wherein in the infrared band film layer, from a light incidence direction to the substrate, the thicknesses of each layer in sequence are as follows: 0.7 to 0.8 μm germanium, 0.95 to 1.5 μm zinc sulfide, 0.7 to 0.8 μm germanium, 0.5 to 0.6 μm zinc sulfide, 0.2 to 0.3 μm germanium, 0.4 to 0.5 μm zinc sulfide, 0.15 to 0.25 μm germanium, 0.4 to 0.5 μm zinc sulfide, 0.5 to 0.6 μm germanium, 1.2 to 1.3 μm zinc sulfide, 0.65 to 0.75 μm germanium.

7. The multiband compatible heat dissipating functional infrared stealth material of claim 1, wherein the microwave-compatible metal-lossy conducting layer-metal super surface structure comprises:

the top copper clad laminate is arranged close to the optical film structure;

a bottom copper-clad plate;

and the ITO conductive loss layer is positioned between the top copper clad laminate and the bottom copper clad laminate.

8. The multiband compatible heat dissipating functional infrared stealth material of claim 7, wherein the top layer copper-clad laminate comprises a circuit board I and square copper plates I arranged in a periodic array on the circuit board I; the ITO conductive loss layer comprises a transparent film and a square indium tin oxide layer arranged on the transparent film in a periodic array mode; the bottom copper-clad plate comprises a circuit board II and a copper plate II arranged on the circuit board II.

9. The multiband compatible heat dissipation functional infrared stealth material of claim 7, wherein the copper plate I has a side length of 3 to 4mm, the ITO layer has a side length of 8 to 12mm, one square ITO layer is opposite to 3 x 3 square copper plates I, and the array period of the square ITO layer is 10 to 12 cm.

10. The multiband compatible heat dissipation functional infrared stealth material of any one of claims 1 to 9, satisfying:

the reflectivity of light with the wavelength of 3-5 mu m wave band is more than 0.85;

the reflectivity of light with the wavelength of 8-14 mu m wave band is more than 0.85;

the absorptivity to light with wavelength of 10.6 μm wave band is above 0.85;

the absorptivity to light with wavelength of 5-8 μm wave band is above 0.5;

the absorptivity of microwave X wave band is above 0.9.

Technical Field

The invention relates to a multiband stealth material with a heat dissipation function and compatibility with visible light, mid-infrared, laser and microwave, and belongs to a novel stealth material based on an optical thin film structure and a microwave super-surface structure.

Background

On the premise that military radar detection technology is mature day by day, stealth technology adopted aiming at different detection radars becomes an important means for improving the battlefield viability of military targets. In traditional stealth techniques for military targets, emphasis is mainly placed on the highly absorptive nature of microwave radiation, mainly in the X-band (8-12GHz), for microwave radar. The continuous updating of the detection means, the thermal infrared imager and the infrared tracking missile for collecting the thermal radiation of the object with an infrared atmospheric window (3-5 microns and 8-14 microns), the active laser radar adopting a high-power carbon dioxide laser (with the wavelength of 10.6 microns) and the optical imaging in the visible light band all pose new threats to military targets covered by the traditional microwave stealth materials.

In the face of combining detection technologies of different electromagnetic wave bands, the existing research mainly realizes invisible materials compatible with infrared heat radiation and microwave or invisible materials compatible with visible light and infrared heat radiation. The realization of multi-band stealth materials covering microwaves, infrared thermal radiation, laser and visible light requires exploration.

Disclosure of Invention

Aiming at the defects and shortcomings of the existing stealth materials and stealth technologies, the invention provides a multiband stealth material which combines an optical thin film structure suitable for infrared and visible light bands and a metal-loss conducting layer-metal super-surface structure suitable for microwaves, and realizes low radiation of an infrared atmospheric window (3-5 mu m and 8-14 mu m), low reflection of a carbon dioxide laser under wavelength, color of the visible light band used for optical camouflage and efficient absorption of a microwave X-band (8-12 GHz). And, it is not the detection wave band (5-8 μm) at infrared non-atmospheric window wave band simultaneously, realize the high radiation and realize the function that the supplementary heat dissipation of heat radiation.

A multiband compatible heat dissipation functional infrared stealth material comprises an optical thin film structure of infrared and visible light bands and a metal-loss conducting layer-metal super surface structure suitable for microwaves, and meets the following requirements:

the reflectivity of light with the wavelength of 3-5 mu m wave band is more than 0.8;

the reflectivity of light with the wavelength of 8-14 mu m wave band is more than 0.8;

the absorptivity to light with wavelength of 10.6 μm wave band is above 0.8;

the absorptivity to light with wavelength of 5-8 μm wave band is above 0.5;

the absorptivity to microwave X wave band is above 0.8.

The invention combines an optical thin film structure suitable for infrared and visible light wave bands and a multiband stealth material suitable for a metal-loss conducting layer-metal super-surface structure of microwave, and realizes low radiation of an infrared atmospheric window (3-5 mu m and 8-14 mu m), low reflection of a carbon dioxide laser under wavelength, color of the visible light wave band used for optical camouflage and efficient absorption of a microwave X wave band (8-12 GHz).

Preferably, the optical thin film structure of the infrared and visible light wave bands consists of a substrate, an infrared light wave band film layer and a visible light wave band film layer; the infrared band film layer consists of high-refractive-index material film layers and low-refractive-index material film layers which are sequentially and alternately deposited on the substrate, and the innermost layer and the outermost layer are high-refractive-index material film layers; the visible light wave band film layer is a low refractive index material film layer, and the thickness of the film layer is far less than lambda₁/(4n₁) Wherein n is₁Is the refractive index, λ, of the material of the film₁Is a medium infrared wavelength, and is generally 3 to 14 μm. Preferably, the thickness of the visible light wave band film layer is 1-30 nm.

As a specific preferable scheme, the optical thin film structure suitable for infrared and visible light bands in the multiband compatible heat dissipation functional infrared stealth material is based on a silica or other infrared absorption substrate, a germanium-zinc sulfide thin film system is deposited on the substrate, the medium infrared band function is based on a distributed Bragg reflector, and the visible light is based on an antireflection film structure formed on germanium by a surface monolayer of zinc sulfide.

Preferably, the high refractive index material is germanium; the low refractive index material is selected from one or more of zinc sulfide, zinc selenide, barium fluoride and calcium fluoride.

Preferably, the high refractive index material is germanium, and the low refractive index material is zinc sulfide.

Preferably, the total number of the high-refractive-index material thin film layers and the low-refractive-index material thin film layers is 11-15, and the thickness of at least one high-refractive-index material thin film layer is smaller than lambda₂/(4n₂) Wherein n is₂Is the refractive index, λ, of the material of the film₂Is 8-14 μm.

Preferably, the substrate is selected from silicon dioxide, aluminum oxide, and the like. The thickness is required to be far larger than the wavelength of the middle infrared (3-14 μm), such as more than 100 μm, and more preferably 100-1000 μm.

Preferably, in the germanium-zinc sulfide multilayer optical film system structure, in the germanium-zinc sulfide multilayer optical film system corresponding to the infrared band DBR high reflection structure and the 10.6 narrow band high absorption, that is, in the infrared band film layer, from the light incidence direction to the substrate, the thicknesses of the layers are, in order: 0.7 to 0.8 μm germanium, 0.95 to 1.5 μm zinc sulfide, 0.7 to 0.8 μm germanium, 0.5 to 0.6 μm zinc sulfide, 0.2 to 0.3 μm germanium, 0.4 to 0.5 μm zinc sulfide, 0.15 to 0.25 μm germanium, 0.4 to 0.5 μm zinc sulfide, 0.5 to 0.6 μm germanium, 1.2 to 1.3 μm zinc sulfide, 0.65 to 0.75 μm germanium. Wherein, 0.15-0.25 μm Ge does not satisfy the quarter wavelength condition of DBR, and is a condition of introducing 10.6 μm narrow-band high absorption.

Preferably, in the germanium-zinc sulfide multilayer optical film system structure, in the germanium-zinc sulfide multilayer optical film system corresponding to the infrared band DBR high reflection structure and the 10.6 narrow band high absorption, that is, in the infrared band film layer, from the light incidence direction to the substrate, the thicknesses of the layers are, in order: 0.728 μm germanium, 0.992 μm zinc sulfide, 0.728 μm germanium, 0.567 μm zinc sulfide, 0.236 μm germanium, 0.444 μm zinc sulfide, 0.208 μm germanium, 0.444 μm zinc sulfide, 0.558 μm germanium, 1.200 μm zinc sulfide, 0.709 μm germanium. Where 0.208 μm of germanium does not meet the quarter-wavelength condition of a DBR, is a condition to introduce a narrow band high absorption of 10.6 μm.

Experiments prove that the germanium-zinc sulfide multilayer optical film system structure can realize low radiance of 0.135 in a wave band of 3-5 mu m and 0.101 in a wave band of 8-14 mu m in an infrared atmospheric window, and has high absorptivity of 0.87 at a position of 10.6 mu m of a carbon dioxide laser. Meanwhile, outside the infrared atmospheric window, the non-infrared detection band 5-8 μm has a radiance of 0.6, and under the condition that the structural temperature is higher than the atmospheric temperature, the auxiliary radiation heat dissipation function can be realized.

Taking the above specific preferred embodiment as an example, in the structure of the germanium-zinc sulfide multilayer optical film system, the principle of realizing different colors of visible light is that the thickness of germanium at the uppermost layer of the infrared DBR is 0.728 μm, and germanium is a high-loss dielectric layer in the visible light band, and the imaginary part of the refractive index of germanium is relatively large, so that the germanium layer can be regarded as having a sufficiently large optical thickness in the visible light band, and other parts of the infrared DBR do not affect the visible light reflection spectrum; at this time, the thickness change of the uppermost single-layer thin zinc sulfide brings about interference cancellation under a certain wavelength in a visible light wave band, high absorption under the wavelength is caused, and the influence on other wavelengths is small, namely, modulation of a visible light reflection spectrum is generated, and different colors are generated.

In the invention, the metal-loss conducting layer-metal super-surface structure suitable for microwaves in the multiband compatible heat dissipation functional infrared stealth material is based on a double-layer copper-clad plate and a middle ITO (indium tin oxide) conducting loss layer three-layer structure.

Preferably, the metal-lossy conducting layer-metal super-surface structure suitable for microwave comprises:

the top copper clad laminate is arranged close to the optical film structure;

a bottom copper-clad plate;

and the ITO conductive loss layer is positioned between the top copper clad laminate and the bottom copper clad laminate.

Preferably, the top copper-clad plate comprises a circuit board I and a square copper plate I arranged on the circuit board I in a periodic array manner; the ITO conductive loss layer comprises a transparent film and a square indium tin oxide layer arranged on the transparent film in a periodic array mode; the bottom copper-clad plate comprises a circuit board II and a copper plate II arranged on the circuit board II.

Preferably, the side length of the copper plate I is 3-4 mm, the side length of the indium tin oxide layer is 8-12 mm, one square indium tin oxide layer is opposite to 3 multiplied by 3 square copper plates I, and the array period of the square indium tin oxide layer is 10-12 cm.

Preferably, in the copper-FR 4/ITO/FR 4-copper super-surface structure, the thicknesses of copper layers in upper and lower copper clad laminates are both 18 mu m, and the thickness of a circuit board (FR4 layer) is both 1 mm. The intermediate layer of ITO was 175nm thick and was coated on a layer of 0.175mm thick PET film. The ITO in the middle layer is a square array, the period of each unit is 11cm, and the side length of the ITO square is 8.1 mm. The upper copper clad laminate has the same period with the ITO, but one period has 3 x 3 copper squares, and the side length of each square is 3.2 mm. The size of the structure belongs to a sub-wavelength structure relative to the applied microwave X-band wavelength (2.5-3.75 cm), so the structure is called a metal-loss conducting layer-metal super surface structure. The low order magnetic resonances formed in the structure enhance the electric field strength in the structure, resulting in a high absorption of the structure above 90% in the 8-12GHz band, i.e. a return loss greater than 10 dB.

As a more preferable scheme, the following are satisfied:

the reflectivity of light with the wavelength of 3-5 mu m wave band is more than 0.85;

the reflectivity of light with the wavelength of 8-14 mu m wave band is more than 0.85;

the absorptivity to light with wavelength of 10.6 μm wave band is above 0.85;

the absorptivity to light with wavelength of 5-8 μm wave band is above 0.5;

the absorptivity of microwave X wave band is above 0.9.

The technical scheme of the invention is a composite structure combining an optical thin film structure suitable for infrared and visible light wave bands and a metal-loss conducting layer-metal super-surface structure suitable for microwaves. The composite structure comprises two parts, a germanium-zinc sulfide multilayer optical film system structure positioned on the upper layer and a copper-FR 4/ITO/FR 4-copper super-surface structure positioned on the lower layer. The germanium-zinc sulfide multilayer optical film system structure is based on a silicon dioxide substrate, film layers with germanium and zinc sulfide alternating are deposited, the thickness of the film layers meets the requirement of 3-5 mu m and 8-14 mu m Distributed Bragg Reflector (DBR) reflection enhancement, specific change of the thickness of one of the germanium layers is introduced, and 10.6 mu m narrow-band high absorption is achieved. And plating a layer of zinc sulfide on the upper surface (interface with air) of the DBR structure of the infrared band, and realizing the reflection spectrum of the visible light band by adjusting the thickness of the zinc sulfide layer so as to generate different colors. The copper-FR 4/ITO/FR 4-copper super surface structure is based on a two-layer bottom-to-bottom copper-clad circuit board (circuit board material is FR4), and an ITO layer plated on PET is sandwiched in the middle. The copper-clad plate on the upper layer is a periodic square array, and the copper-clad plate on the lower layer is a complete layer.

The invention relates to a stealth material which is compatible with infrared, microwave, visible and laser multiband and has radiation-assisted heat dissipation. The infrared, visible and laser stealth is based on a germanium-zinc sulfide multilayer optical film system structure, the stealth of an infrared atmospheric window waveband is realized by utilizing the high reflection characteristic of an infrared DBR, and the variable color is realized by utilizing a surface antireflection film. The microwave stealth is based on a metal-loss conducting layer-metal microwave super-surface structure, and high absorption in an X wave band is achieved. Because the radiation-assisted heat dissipation is realized by utilizing the non-atmospheric window wave band, the heat accumulation of the device for realizing infrared stealth can be effectively avoided. Meanwhile, the microwave super-surface structure has smaller thickness and unit area weight, and can effectively avoid extra weight burden caused by stealth materials.

The invention has the advantages that: (1) aiming at the electromagnetic wave detection technology with different wavelengths, the optical material and the structure are optimized by utilizing the difference of the wavelengths so as to realize the multi-band compatible stealth material; (2) the non-infrared atmospheric window wave band is reasonably utilized for radiation heat dissipation, so that heat accumulation caused by infrared stealth is avoided; (3) compared with the traditional microwave stealth material or structure, the metamaterial structure is utilized to realize high-efficiency absorption under the condition of smaller thickness and smaller unit area weight.

Drawings

FIG. 1 is a schematic diagram of the structure of a Ge-ZnS multilayer optical film system and the distribution of the electric field intensity under a normal incidence of 10.6 μm light.

FIG. 2 shows the change in infrared reflectance and the location of the visible color in the CIE1931 color coordinate when the thickness of the zinc sulfide film on the surface layer of the Ge-Zn sulfide multilayer optical film system is changed from 1 to 30 nm.

FIG. 3 is a schematic diagram of a metal-lossy conducting layer-metal microwave super-surface structure, and the absorption rate in the 8-12GHz band and the magnetic field intensity distribution in the 8GHz and 12GHz position structures.

Fig. 4 is a schematic structural diagram of an embodiment of a multiband compatible heat dissipation functional infrared stealth material.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings in which: the present embodiment is based on the present invention, but the scope of the present invention is not limited to the following embodiments and examples.

As shown in fig. 4, it is an embodiment of the present invention, which includes a top optical thin film structure in the infrared and visible light bands and a metal-lossy conducting layer-metal microwave super-surface structure (metal-lossy conducting layer-metal super-surface structure) suitable for microwave.

As shown in fig. 1, the optical film structure of infrared and visible light bands is composed of a substrate, an infrared light band film layer and a visible light band film layer. In this example, silicon dioxide (thickness 1mm) was selected as the substrate. Germanium and zinc sulfide films are sequentially deposited on a silicon dioxide substrate in an electron beam evaporation mode, and the thicknesses of the germanium and the zinc sulfide films from top to bottom (along the direction of incident light) are respectively 0.728 mu m of germanium, 0.992 mu m of zinc sulfide, 0.728 mu m of germanium, 0.567 mu m of zinc sulfide, 0.236 mu m of germanium, 0.444 mu m of zinc sulfide, 0.208 mu m of germanium, 0.444 mu m of zinc sulfide, 0.558 mu m of germanium, 1.200 mu m of zinc sulfide and 0.709 mu m of germanium. In the case of zinc sulfide thin film without a surface layer for forming color, under the irradiation of 10.6 μm carbon dioxide laser, the thickness of 0.208 μm of germanium in the middle from bottom to top layer 6 (substrate is the first layer) does not satisfy the quarter wavelength condition of DBR, so that the electric field intensity is larger at the position, and 10.6 μm narrow-band high absorption is generated.

As shown in FIG. 2, the germanium-zinc sulfide multilayer optical film system structure can realize low radiance of 0.135 in a wave band of 3-5 μm and 0.101 in a wave band of 8-14 μm in an infrared atmospheric window, and simultaneously has high absorptivity of 0.87 at a position of 10.6 μm of a carbon dioxide laser. Meanwhile, outside the infrared atmospheric window, the non-infrared detection band 5-8 μm has a radiance of 0.6, and under the condition that the structural temperature is higher than the atmospheric temperature, the auxiliary radiation heat dissipation function can be realized (the thickness of the visible light band film layer corresponding to the result is 1-30nm, and the specific thickness can be determined according to the target color requirement).

As shown in fig. 2, the visible light band film layer is a zinc sulfide film. Under the condition that the thickness of the zinc sulfide film used for forming the color on the surface is changed from 1nm to 30nm, the response (reflection curve) of the whole germanium-zinc sulfide multilayer optical film system structure to the middle infrared ray is not greatly influenced. While the thickness of the zinc sulfide film used for forming the color on the surface is changed from 1nm to 30nm, so that the reflection spectrum of the optical film system structure for visible light is changed, and different colors are generated, wherein the visible color is described as a scattered point in a CIE1931 chromaticity coordinate system.

As shown in fig. 3, the metal-loss conductive layer-metal microwave super-surface structure is composed of three parts, namely a copper-clad plate I with an upper copper surface facing upward, a PET film with an ITO film plated in a middle layer, and a copper-clad plate II with a lower copper surface facing downward. The upper copper clad laminate I consists of a circuit board FR4 and a copper layer I plated on the upper surface of the circuit board. The copper-clad plate II with the copper surface facing downwards consists of a circuit board FR4 and a copper layer II plated on the lower surface of the circuit board. The thickness of each of copper layer I and copper layer II was 18 μm, and the thickness of the circuit board (FR4 layer) was 1 mm. The intermediate layer of ITO was 175nm thick and was coated on a layer of 0.175mm thick PET film. The uppermost and lowermost copper layers serve as the metal, while two layers of FR4 and the intermediate layer of ITO serve as the lossy conducting layers. The ITO in the middle layer is a square array, the period of each unit is 11cm (the array period in the x direction and the array period in the y direction are both 11cm), and the side length of the ITO square is 8.1 mm. The copper layer I on the upper copper-clad plate has the same array period as the ITO, but each period has 3 x 3 copper squares, the side length of each square is 3.2mm, namely, one middle layer ITO corresponds to 3 x 3 copper squares. The size of the structure belongs to a sub-wavelength structure relative to the applied microwave X-band wavelength (2.5-3.75 cm), magnetic resonances at different positions are formed at 8GHz and 12GHz respectively, wherein the magnetic field intensity of 8GHz is higher between ITO and lower layer copper, and the magnetic field of 12GHz is distributed stronger between upper layer copper and ITO. The low order magnetic resonances formed in the structure enhance the electric field strength in the structure, resulting in a high absorption of the structure above 90% in the 8-12GHz band, i.e. a return loss greater than 10 dB.