Study On The Influence Of Temperature Change On BRDF Of Aluminum Materials

BRDF(Bidirectional Reflectance Distribution Function, BRDF) is an important physical parameter to describe the surface reflection properties of various materials, at present, it is widely used in the field of the research of the target scattering characteristics, space remote sensing, computer image processing and so on. In the last few years, most researches of surface scattering characteristics based on BRDF theory are carried out in the indoor temperature environment. However, in the process of the satellite and other spacecraft launching or returning, the change of temperature changes the surface BRDF compared to the indoor temperature, brings difficulty to imaging tracking etc. To sum up, this paper carries out the research on the effect of temperature variation on the surface BRDF of the aluminum material, and combines with the principle of BRDF and the method of scattering spectrum analysis. The main contents of this paper are as follows:(1) Through depth study of the measuring principle of the BRDF, based on the definition of BRDF formula, the surface scattering spectrum measurement system is set up by means of the marine spectrometer, the sun light simulator, the optical fiber, the detector and the data computer. By applying the method of scattering spectrum analysis, the factors which affect the materials' surface scattering spectra is analyzed under certain conditions. Different surface roughness of aluminum plates which are 0.8 and 50 are selected. The results show that the surface roughness affect the scattering spectra. Grating structure surface is obtained by femtosecond laser processing on the surface of aluminum and copper sheet, and it is found that materials' scattering spectrum is affected by the microstructure of the surface.(2) BRDF analysis method is used to analyze the data of aluminum surface's scattering spectrum from the temperature of 25? to 500?. The relative measuring method is applied, the PTFE standard plate is selected, and the BRDF value of the every interval 100? is obtained. Through the comparison analysis, the influence of temperature change on the surface of BRDF is obtained. Temperature increases, the surface BRDF value increases, and temperature decreases, the surface BRDF value decreases. The results of the research have practical effect on target detection.(3) In error analysis of the accuracy of the experiment, the errors are mainly derived from the error of the measuring temperature and the actual temperature and effects of stress on the surface of aluminum plate in heating process. The real temperature value of the material surface is obtained by the method of temperature fitting, and the error is 6.4%. Stress and strain effects on the material surface are simulated by applying COMSOL simulation software, and it is concluded that the stress and strain in heating process are not sufficient enough to affect the experimental results.