Research On Modeling And Simulation Of Infrared Radiation Polarization

The infrared radiation detection can only measure the radiation intensity of the surface of an object. When there is an interference object which have the same temperature, it can not be distinguished with the target object. Infrared polarization detection can not only measure the radiation intensity of the surface of an object, but also the radiation of different polarization direction. The polarization characteristics of different obeject surfaces are different, so the infrared polarization detection is able to distinguish the target and the interference, has become one of the hot research topics.In the traditional study of infrared radiation polarization, the researcher use the difference between the parallel and perpendicular components of the emissivity of the infrared radiation divided by the sum of them to represent the degree of polarization. They use Fresnel’s Formula to calculate Fresnel reflectance and then according to the relationship between the emissivity and reflectance get the infrared radiation polarization model based on Fresnel. The Fresnel reflectance is derived in the prerequisite of the specular reflection from the surface, which can only be suitable to an ideal object that have a smooth surface. Thus, the traditional model measure the complex refractive index of object surfaces of different roughness and put the data to the model to calculate the infrared radiation polarization characteristics of object surfaces with different roughness. However, the method neglects the microscopic distribution of the rough surface and the final conclusion is not exactly correct.Traditional infrared radiation polarization model ignores the microscopic distribution, and taking this into cosideration this thesis expand theoretical studies and modeling and simulation of infrared radiation polarization characteristics.This thesis model the degree of polarization of the infrared radiation based on the microfacet polarized bidirectional reflectance distribution function (pBRDF) and the microstructure distribution.Firstly, I research on BRDF and introduce the microfacet BRDF to improve the traditional infrared radiation polarization model, and get the relationship between emissivity and hemispherical reflectance according to the Kirchhoff s law and the microfacet BRDF.Then, I study how to polarize the microfacet BRDF to calculate the directional hemispherical reflectance and then get directional emissivity matrix to calculate the degree of polarization, and last establish the model of the infrared radiation polarization baced on the polarization BRDF to carry on the simulation experiment and analyze it. The experimental results show that the degree of the infrared radiation polarization are consistent with the actual measured values, and that compared with the simulation results of traditional infrared radiation polarization model is closer to the measured value, especially in the case of the surface roughness is larger, can more accurately reflect the infrared radiation polarization characteristics.In the end, this thesis model the typical material objects to simulate their infrared radiation polarization degree images, to further verify the correctness of the model in this thesis and illustrate that the infrared radiation polarization image will be better able to distinguish the target object and the image detail texture information can be more abundant.