| The radiation character of the target and environment reflects the physical phenomenon caused by the interaction of light-wave on the target and the environment which reveals the inherent nature of target and environment. BRDF is a fundamental quantum which describes the space reflectance characteristics of material surface, popularly used on the scope of space remote sensing, geological survey, and accurate restrain missile and maneuvering target tracking. Currently, the study of material surface BRDF is only within the scope of room temperature because of the limitation of the experimental technology. But the surface temperature may be changed in reality, which results in the surface BRDFs different from the ones under room temperature. Consequently, the BRDF theory and experiment studies under temperature effects are developed in this thesis. The research comes from the key project of National Natural Science Foundation of China (50336010), and the purpose of this project is to develop a temperature controllable BRDF measurement system with uncertainty better than 15%. By means of this equipment, the theoretical and experimental study on the temperature effects on the material BRDF is realized. It also provides BRDF measure database under different temperature.Based on the specific aspect of the experimental calibration and the BRDF measurement under different temperature, combining the development of the temperature controllable BRDF measurement instrument, the thesis elaborates the BRDF theory deeply, BRDF measurement method, light scattering theory, module parameter optimizing and the evaluation method of the measure uncertainty. The finished research works are as follows:⒈Research on electromagnetic scattering characteristics of material surface. Combining the fractal theory, the formula for calculating the electromagnetic scattering fields and scatter cross is deducted for the FBM rough surface by using the Kirchhoff approximation theory, and the scatter cross is calculated numerically and its result is compared with the scatter results of Gaussian distribution and index Correlation distribution for rough surface. Suitable fractal dimension and statistical measurement for granite surface are chosen based on the FBM function; its BRDF values are simulated, compared and analyzed with the experimental results.⒉Basing on the BRDF relative measurement theory, a temperature controllable BRDF measurement system which combining the light, mechanic and electric performance is developed. Considering the suppression on stray radiation in measurement, an off-axis structure is used for the circuit. The collimation, reflection, optical modulation, centralization and the photoelectric signal receiving system are designed. A heating furnace for the sample heating and a temperature controllable device are developed. Temperature is controlled by fuzzy PID controller. Four lasers are used with the wavelength of 0.6328μm, 1.34μm, 3.39μm and 10.6μm as the light source, which could realize the sample multi-spectrum BRDF measurement under different temperature.⒊BRDF experimental research for several typical materials is completed with the help of the equipment. Under the condition of room temperature, the variation of various materials BRDF verifying with roughness, wavelength and other factor are studied. From 25℃to 500℃, the variation of Cu surface, Teflon surface and graphite surface BRDF with the temperature is studied. The experimental results are analyzed finally.⒋BRDF models parameter optimization research based on the genetic algorithm. The advantages and disadvantages of target surface BRDF and other BRDF models are analyzed. The corresponding BRDF parameter models are established through the BRDF experimental studies for several typical materials. And the parameters are optimized by means of genetic algorithm. The Cu model parameter is inversed based on the genetic algorithm and least square method, and then the results are compared and analyzed.⒌Research on the uncertainty and the experimental calibration method of BRDF measurement. The uncertainty reasons are analyzed theoretically and the error factors influencing the system accuracy are also analyzed quantatively. By utilizing the entire root mean square error method, an error analysis method for the BRDF measurement is provided. Meanwhile, the analyzed results are verified according to the experimental calibration method.The studied contents of the thesis establish a strong technical and theoretical foundation for the material surface BRDF database under different temperature.
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