Low-laser-reflection, low-thermal-infrared-window-radiation and 5-7.5-micron-waveband intense-radiation refrigeration multifunctional integrated thin film

Abstract

The invention discloses a multifunctional integrated film with low laser reflection, low thermal infrared window radiation and 5-7.5 [mu] m wave band strong radiation refrigeration, a heterogeneous film system structure of the integrated film is Ge / ZnS / Ge / ZnS / Ge, the integrated film is formed by alternately arranging two optical film materials of Ge and ZnS, the thickness of Ge film layers located on two sides is 598.5-661.5 nm, the thickness of the Ge film layer located in the middle is 1197-1323 nm, and the thickness of the ZnS film layer is 1092.5-1207.5 nm. The multifunctional integrated thin film is applied to serving as or preparing a material with the laser and infrared compatible stealth function, the thermal insulation function within the large-range wavelength of a thermal infrared atmospheric window and / or the passive radiation refrigeration function of a non-infrared window. The multifunctional integrated film disclosed by the invention can be used for stealth protection and thermal management in the fields of photoelectric confrontation, buildings, automobiles and the like, and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to a multifunctional integrated film with low laser reflection, low thermal infrared window radiation and strong radiation refrigeration in the 5-7.5 μm band, belonging to the technical field of photothermal regulation materials. Background Art

[0002] Photothermal control technology plays an important role in modern science and technology and social development, and is developing towards multifunctional integration. At present, there is an urgent need for multifunctional integrated photothermal control film technology with low laser reflection, low thermal infrared radiation suppression and passive radiation cooling in many fields such as military, construction, and automobiles. However, traditional materials and structures are very weak in manipulating the transmission characteristics of light and thermal electromagnetic waves according to human will, and it is difficult to reconcile the conflicting spectral demands of the thermal infrared band for radiation, light trapping, reflection, etc., which makes it difficult to achieve the multifunctional integration goal in the thermal infrared band, which seriously restricts the optimization and expansion of performance.

[0003] The thermal infrared atmospheric windows are mainly 3-5μm (medium-wave infrared window) and 7.5-14μm (long-wave infrared window). There is a small absorption rate in the atmosphere in these two bands, and they are in a high transmittance state in the atmosphere; therefore, the working bands of thermal infrared detection technology are usually 3-5μm and 7.5-14μm, and the design of thermal shielding blocking materials and infrared stealth materials needs to focus on ensuring the low radiation state in the above two bands. In other thermal infrared bands (such as 5-7.5μm between the above two bands), it is easier to interact with water vapor, carbon dioxide and other substances in the atmosphere and be absorbed and consumed, which can be used as the working band of radiation cooling, so as not to affect the infrared stealth performance and the thermal shielding effect on the atmospheric environment. The 10.6μm laser band, thermal infrared window (3-5μm and 7.5-14μm), and 5-7.5μm non-infrared atmospheric window radiation cooling band are all thermal infrared bands, and there are partial overlaps or adjacent situations, which makes it difficult for materials to simultaneously meet the different optical and thermal performance requirements in these interrelated bands. To achieve multifunctional integration in the thermal infrared band, materials need to selectively regulate and design different bands with completely conflicting spectral appeal principles, such as the conflict between the overlapping bands of 10.6μm wavelength laser low reflection and 7.5-14μm wavelength thermal infrared low radiation (i.e. high reflection), and the conflicting appeal relationship between the adjacent bands of 3-5μm, 7.5-14μm thermal infrared window low radiation and 5-7.5μm band high radiation cooling. It is difficult for existing materials to accurately distinguish between these bands and achieve their respective target performance, because the optical and thermal properties of materials are often interrelated, and changing the performance of one band may affect the performance of other bands, restraining each other. Summary of the invention

[0004] In view of the above-mentioned prior art, the present invention provides a multifunctional integrated film with low laser reflection, low thermal infrared window radiation and strong radiation cooling in the 5-7.5 μm band and its application.

[0005] The present invention is achieved through the following technical solutions: A multifunctional integrated film with low laser reflection, low thermal infrared window radiation and strong radiation cooling in the 5-7.5 μm band, wherein the heterogeneous film system structure is Ge / ZnS / Ge / ZnS / Ge, and is composed of two optical thin film materials, Ge and ZnS, arranged alternately, with a total of 5 layers of films, among which the thickness of the Ge film layers on both sides is 598.5-661.5 nm, the thickness of the Ge film layer in the middle is 1197-1323 nm, and the thickness of the ZnS film layer is 1092.5-1207.5 nm.

[0006] Preferably, the thickness of the Ge film layer on both sides is 630 nm, the thickness of the Ge film layer in the middle is 1260 nm, and the thickness of the ZnS film layer is 1150 nm.

[0007] Preferably, the thicknesses of the five layers of film from inside to outside are: 656 nm, 1141 nm, 1260 nm, 1152 nm, and 635 nm.

[0008] The application of the multifunctional integrated thin film with low laser reflection, low thermal infrared window radiation and strong radiation cooling in the 5-7.5 μm band as or in the preparation of materials with laser and infrared compatible stealth, thermal infrared atmospheric window heat isolation in a wide range of wavelengths and / or non-infrared atmospheric window passive radiation cooling functions. In specific applications, Ge film layer, ZnS film layer, Ge film layer, ZnS film layer and Ge film layer are sequentially plated from the inside to the outside on the surface of the substrate by magnetron sputtering or vacuum evaporation coating process. The substrate is selected from a silicon wafer substrate.

[0009] The multifunctional integrated thin film of the present invention with low laser reflection, low thermal infrared window radiation and strong radiation cooling in the 5-7.5 μm band forms the synergistic effect of photon bandgap, interface photon localization and symmetrical cavity optical effect by using heterogeneous multilayer film structure, and enhances the spectrum selection characteristic regulation of light in different bands and film system structure; it realizes wide-range strong reflection in the two thermal infrared bands of 3-5 μm and 7.5-14 μm to realize low radiation state (to counter infrared thermal imaging detection and heat shielding); it realizes strong radiation cooling in the 5-7.5 μm thermal infrared band (heat dissipation is easily absorbed by the atmosphere); it realizes the "spectral hole digging" effect of narrow-range strong absorption and light trapping at the 10.6 μm wavelength laser. The multifunctional integrated thin film of the present invention has the theoretical configuration and film thickness of Ge (630 nm) / ZnS (1150 nm) / Ge (1260 nm) / ZnS (1150 nm) / Ge (630 nm), and the coating error of each layer is controlled within ±5%.

[0010] The multifunctional integrated film of the present invention has low reflection at 10.6 μm laser, low radiation at thermal infrared window and strong radiation cooling at 5-7.5 μm band, which can resolve the conflicting spectral demands of different functions in multiple bands and realize multifunctional integration. It shows great application prospects in the fields of military, construction, automobile, etc., significantly improves the performance and benefits in various fields, and is expected to bring more positive impacts on future scientific and technological development and social progress.

[0011] In the military field, the application of the integrated technology of the present invention can realize photoelectric stealth camouflage and thermal management to enhance combat capabilities. In the modern military photoelectric confrontation environment, weapons and equipment are facing the threat of laser and infrared joint detection methods. Laser detection mainly uses the reflection characteristics of 10.6μm wavelength laser to detect targets; while infrared detection is based on the high-temperature thermal radiation characteristics of the target, mainly using the thermal imaging principle that thermal infrared has high transmittance, low attenuation and is easy to detect in the two atmospheric window bands of 3-5μm mid-infrared and 7.5-14μm far-infrared; at the same time, passive radiation cooling technology can dissipate the heat on the surface of the equipment in the form of infrared radiation of a specific wavelength into the low-temperature universe, without the need for cooling energy consumption, to achieve cooling. On the one hand, lowering the temperature of the equipment helps infrared stealth and reduces the exposure of the equipment's own thermal radiation in the infrared band. On the other hand, appropriate temperature reduction can reduce the changes in laser reflection characteristics caused by excessive temperature, which helps maintain the laser stealth performance. In order to improve the comprehensive protection performance of equipment, it is often necessary to pursue the multifunctional integration of low laser reflection, low radiation of thermal infrared window and passive radiation cooling, so that the equipment has low detectability in laser and infrared joint detection, and ensures that the equipment maintains stable performance in a specific environment.

[0012] In the field of architecture, the application of the integrated technology of the present invention can help energy conservation and indoor environment regulation, and create a comfortable space. Low-radiation infrared radiation with a wide range of wavelengths can reduce the absorption of solar infrared radiation, like putting on a layer of "insulating clothing" for the building, reducing the indoor temperature. At the same time, the integrated part of radiation refrigeration can dissipate the heat accumulated in the building during the day through infrared radiation at night, thereby reducing the use of refrigeration equipment such as air conditioners, and achieving the purpose of energy saving. In addition, for some buildings with high privacy requirements, such as residential buildings and office buildings, the technology of low laser reflection and low radiation of thermal infrared windows can prevent external lasers and infrared thermal imaging detection equipment from detecting the activities of people indoors, and play a role in privacy protection. In this way, the energy-saving purpose of balancing insulation and refrigeration is achieved, as well as the effect of taking into account both privacy protection and comfort.

[0013] In the automotive field, the application of the integrated technology of the present invention can achieve energy saving, improve comfort and safety. After a car is exposed to the sun, the temperature inside the car will rise sharply. The car shell material using this integrated technology can reduce the absorption of solar infrared radiation and reduce the temperature inside the car. At the same time, during the driving process of the car, the heat generated by the engine and other parts can be effectively dissipated through radiation cooling, thereby improving the performance of the car and the driving comfort. In addition, in the autonomous driving scenario, anti-laser and infrared detection technology can prevent the vehicle from being interfered with by external laser radars or infrared sensors, and can also prevent external illegal detection equipment from obtaining too much information, thereby ensuring the safety of the vehicle.

[0014] The multifunctional integrated film of the present invention has the advantages of low reflection of 10.6μm laser, low radiation of thermal infrared window and strong radiation cooling in the 5-7.5μm band, and has the advantages of multifunctional integration, simple structure, few film layers, and easy preparation. The present invention realizes the regulation of the spectrum selection characteristics of light in different bands and the film structure, and then realizes the multifunctional integrated effect of laser / infrared compatible stealth, thermal isolation in a wide range of wavelengths, and passive radiation cooling of non-infrared windows. It can be used for stealth protection and thermal management in military and civilian dual-use fields such as optoelectronic confrontation, construction, and automobiles, thereby meeting the application requirements of energy saving, comfort, and safety.

[0015] Various terms and phrases used herein have the general meanings that are well known to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 : Schematic diagram of a heterogeneous film structure deposited on the surface of a silicon wafer substrate.

[0017] Figure 2 : Schematic diagram of the reflective spectrum characteristics of the multifunctional integrated film at 2 to 20 μm.

[0018] Figure 3 : Schematic diagram of the transmission spectrum characteristics of the multifunctional integrated film at 2 to 20 μm.

[0019] Figure 4 : Infrared thermal images of the sample and substrate.

[0020] Figure 5 : Schematic diagram of the electric field mode distribution characteristics of the sample when thermal infrared electromagnetic waves are transmitted, where A, B, C, D, and E are schematic diagrams of the electric field mode distribution characteristics of thermal infrared waves with wavelengths of 4μm, 6μm, 9μm, 10.6μm, and 14μm when they are transmitted inside the film structure. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the embodiments. However, the scope of the present invention is not limited to the following embodiments. It will be appreciated by those skilled in the art that various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention.

[0022] The instruments, reagents, and materials involved in the following examples, unless otherwise specified, are all conventional instruments, reagents, and materials available in the prior art and can be obtained through regular commercial channels. The experimental methods, detection methods, etc. involved in the following examples, unless otherwise specified, are all conventional experimental methods and detection methods available in the prior art.

[0023] Example 1 Multifunctional integrated film A multifunctional integrated film with low reflection for 10.6μm laser, low radiation for thermal infrared window and strong radiation cooling in the 5-7.5μm band. Its heterogeneous film structure has only 5 layers, with two optical thin film materials, Ge and ZnS, arranged alternately. The theoretical configuration and film thickness are: Ge (630 nm) / ZnS (1150 nm) / Ge (1260 nm) / ZnS (1150 nm) / Ge (630 nm), and the coating error of each layer is controlled within ±5%.

[0024] In the specific preparation, a magnetron sputtering coating process is used to sequentially coat heterogeneous film structures on the surface of the silicon wafer substrate, such as Figure 1 As shown, there are 5 layers of film, Ge / ZnS / Ge / ZnS / Ge, and the thickness from the inside to the outside is characterized by testing as Ge (656 nm) / ZnS (1141 nm) / Ge (1260 nm) / ZnS (1152 nm) / Ge (635 nm). The coating errors of each layer from the inside to the outside are only 4.1%, 0.8%, 0%, 0.2%, and 0.8%, which can be controlled within 5%, with good coating accuracy.

[0025] Fourier transform infrared spectrometer was used to characterize and analyze the reflectance spectrum characteristics of the new film material in the 2-20 μm thermal infrared band. The results are as follows: Figure 2 , Figure 3As shown. As can be seen from the figure, it can form a high reflection of ≥85% (i.e., low radiation state) in a large range within the mid-infrared atmospheric window band of 3-4.5μm and the far-infrared atmospheric window band of 7.5-14μm; and at the 10.6μm laser band, a "spectral hole digging" light trapping phenomenon with a narrow-range low reflection of ≤20% and a transmittance close to 0 is achieved, which is due to strong absorption. At the same time, it has low reflection and low transmittance characteristics close to 0 in the 5-7.5μm band, that is, it can achieve strong absorption and lead to strong radiation cooling. It can be seen that the multifunctional integrated film of the present invention can achieve multifunctional integration of low reflection of 10.6μm laser, low radiation of thermal infrared window and strong radiation cooling in the 5-7.5μm band, which can be used to realize multifunctional integrated application scenarios such as laser and mid- and far-infrared compatible stealth, large-scale thermal radiation suppression of mid- and far-infrared windows, and zero-energy passive radiation cooling. It can be used for stealth protection and thermal management in military and civilian dual-use fields such as optoelectronic confrontation, construction, and automobiles, thereby meeting energy saving, comfort, and safety.

[0026] Use a thermal imaging device with a working band of 7.5 to 14 μm, adjust the temperature of the heating stage to 400°C, and take infrared thermal images of the sample and substrate (reference object), such as Figure 4 As shown in the figure, the sample surface temperature is only 160.3℃, while the temperature of the substrate surface is 394℃, a difference of 233.7℃. This is mainly because the sample can inhibit thermal radiation in the 7.5-14μm thermal infrared band and play a role in thermal isolation, and strong radiation cooling in the 5-7.5μm band is also conducive to the cooling of the sample, thereby achieving a good temperature control effect.

[0027] The multi-physics simulation software was used to simulate and calculate the electric field mode distribution characteristics of thermal infrared waves with wavelengths of 4μm, 6μm, 9μm, 10.6μm, and 14μm when they were transmitted inside the film structure. The results are as follows Figure 5 As shown, the vertical axis shows the electric field norm (V / m). As can be seen from the figure, when the thermal infrared wavelength is 4μm, 9μm, and 14μm (i.e., in the two thermal infrared window bands of 3-5μm and 7.5-14μm), the electric field distribution is mainly concentrated at the outer heterogeneous interface. This shows that due to its special periodic dielectric structure, photons in these frequency ranges cannot propagate in it, just like being blocked by an invisible "wall", and these frequency ranges form a strong reflection phenomenon of the "photon bandgap". When the thermal infrared wavelength is 6μm (i.e., in the 5-7.5μm thermal infrared band) and 10.6μm (laser wavelength), the electric field distribution is concentrated at the heterogeneous interfaces in the inner layer and the middle layer respectively. This shows that due to the photon localization effect of the heterogeneous interface, these photons will be confined around these interfaces, forming a localized state, enhancing the mutual light trapping effect between light and matter, thereby realizing efficient control and utilization of light. In particular, the 10.6μm thermal infrared wave forms a significant symmetrical cavity optical effect phenomenon in the middle part of the film structure.

[0028] In summary, the novel thin film material of the present invention utilizes a heterogeneous multilayer film structure to form a synergistic effect of photon bandgap, interface photon localization and symmetric cavity optical effects, thereby enhancing the regulation of the spectrum selection characteristics of light in different bands and the film structure, and achieving wide-range strong reflection in the two thermal infrared bands of 3-5μm and 7.5-14μm, achieving a low-radiation state (to counter infrared thermal imaging detection and heat shielding); achieving strong radiation cooling in the 5-7.5μm thermal infrared band (heat dissipation is easily absorbed by the atmosphere); achieving the "spectral hole digging" effect of narrow-range strong absorption and light trapping at the 10.6μm wavelength laser; and further achieving the multifunctional integrated effect of laser / infrared compatible stealth, thermal isolation in a large range of thermal infrared wavelengths, and passive radiation cooling of non-infrared windows.

[0029] The above examples are provided to those skilled in the art to fully disclose and describe how to make and use the claimed embodiments, and are not intended to limit the scope of the disclosure herein. Modifications that are obvious to those skilled in the art will fall within the scope of the appended claims.

Claims

1. A multifunctional integrated film with low laser reflection, low thermal infrared window radiation and strong radiation cooling in the 5-7.5 μm band, characterized in that: Its heterogeneous film structure is Ge / ZnS / Ge / ZnS / Ge, which is composed of two optical thin film materials, Ge and ZnS, arranged alternately, with a total of 5 layers of films. Among them, the thickness of the Ge film layer on both sides is 598.5~661.5 nm, the thickness of the Ge film layer in the middle is 1197~1323 nm, and the thickness of the ZnS film layer is 1092.5~1207.5 nm.

2. The multifunctional integrated film with low laser reflection, low thermal infrared window radiation and strong radiation cooling in the 5-7.5 μm band according to claim 1, characterized in that: The thickness of the Ge film layer on both sides is 630 nm, the thickness of the Ge film layer in the middle is 1260 nm, and the thickness of the ZnS film layer is 1150 nm.

3. The multifunctional integrated film with low laser reflection, low thermal infrared window radiation and strong radiation cooling in the 5-7.5 μm band according to claim 1, characterized in that: The thicknesses of the five films are 656 nm, 1141 nm, 1260 nm, 1152 nm, and 635 nm, respectively.

4. Use of the multifunctional integrated film with low laser reflection, low thermal infrared window radiation and strong radiation cooling in the 5-7.5 μm band as claimed in claim 1, 2 or 3 as or in the preparation of a material with laser and infrared compatible stealth, thermal isolation in a wide range of wavelengths of the thermal infrared atmospheric window and / or passive radiation cooling of the non-infrared window.

5. The use according to claim 4, characterized in that: In specific applications, a Ge film layer, a ZnS film layer, a Ge film layer, a ZnS film layer and a Ge film layer are sequentially plated on the surface of the substrate from the inside out by magnetron sputtering or vacuum evaporation coating technology.

6. The use according to claim 5, characterized in that: The substrate is selected from a silicon wafer substrate.

Images