Research On Performance Improvement And Rolling Fabrication Technology Of Multiband Stealth Thin Films

At present,multi-band reconnaissance technique poses a great threat to military equipment and personnel.This raises the need to research corresponding stealth technology,so as to improve the survivability of the above-mentioned targets.In this paper,based on the previous research,we continued study the stealth films based on one-dimensional photonic crystals,including the expansion of compatible stealth bands,the improvement of performance in special occasions and the exploration of large-scale fabrication technology.In the aspect of band expansion,firstly,we analyzed the principles of compatible stealth for visible light,thermal infrared,laser and radar wave,which provided theoretical support for the realization of compatible stealth.Then the impurity states were introduced into the 8-14μm high reflection band of far infrared stealth photonic crystals(PCs)by three ways,including changing the thickness of the medium,replacing or inserting new medium,so as to reduce the reflection of 10.6μm laser.On this basis,some compatible stealth photonic crystals for visible light,middle and far infrared and three lasers(0.93μm,1.06μm and 10.6μm)were designed.Finally,the designed PCs were fabricated by coating machine and tested by VIS camera,SEM,infrared thermal imager,Fourier transform spectrometer and vector network analyzer.As a result,for visible band,thin films with different colors can be merged into camouflage pattern,for mid-far infrared bands,thin films with low emissivity could obviously suppress the radiation in 3-5μm and 8-14μm;and for wavelengths of 0.93μm,1.06μm and 10.6μm,thin films with low reflectivity could significantly reduce the echo power of the corresponding lasers.In the aspect of performance improvement,firstly,we analyzed the optimization algorithm of stealth films,which provided a basis for the design of high performance stealth films.In order to reduce the significance of visible detection,the thermal stealth thin films with low glossiness were designed to solve the problem that ordinary stealth thin films are easy to distinguish in the daytime.In order to avoid damage of equipment or deterioration of stealth performance caused by heat accumulation,the stealth thin films with good heat dissipation performance were designed by increasing the transmittance of radiation in 5-8μm.In order to improve the adaptability to the incident angle of laser,the thin films with hign stealth performance for laser were designed by broadening the “photon localization”.In the aspect of large-scale fabrication technique,firstly,we analyzed the working mechanism of rolling vacuum electron beam evaporation coating,and obtained the numerical relationship among deposition thickness,evaporation rate and motion rate of substrate.Then we analyzed the deposition uniformity on the substrate,and designed the shape of correction baffle.Finally,large area thin films were fabricated and tested,which indicated that the rolling vacuum electron beam evaporation coating method can indeed improve the preparation efficiency of stealth thin films.This paper lays a foundation for improving the performance and practicality of stealth films based on one-dimensional photonic crystals.