Infrared Polarization Characteristics Analysis Of Space Targets

Under the background of IT-based warfare,polarizing imaging technology,as a new means of military detection,has a broad application prospect.With the fluctuation of micro rough surface,shadow,shielding effect,etc considered,the calculation model of the polarization degree of surface radiation was established.Combined with the Kramers-Kronig relation,the spectral reflectance of four kinds of materials is simulated.The spectral degree of polarization is calculated to compare with the experimental results and verify the reliability of the model.Based on the mathematical description of Rs in the polarization model,the inversion model of the surface optical constants and roughness parameters is established by measuring the hemispherical reflectivity of the incident light at different angles.On those basises above,the infrared polarization imaging software of the intermediate stage missile is developed to study the characteristics of infrared polarization imaging of space targets.The main contents and conclusions are as follows:(1)Considering the radiation of the rough surface and the reflection of the incident light,the calculation model of the polarization degree of the reflected light and the calculation model of the self-radiation polarization degree are established.Based on them,the influence of different surface factors and environmental factors on the degree of polarization are studied and the results show that the incidence angle,reflection angle and surface optical constant affect the degree of polarization by influencing the reflectivity of different vibration directions.The roughness parameter affects the degree of polarization by influencing the probability density function.(2)Based on the K-K relationship,the spectral optical constants of glass,steel,plastic and aluminum are retrieved.The infrared spectral degree of polarization of those 4 kinds of materials can be obtained by the models mentioned above.The comparison between theoretical and experimental results shows that the theoretical results agree well with the experimental results.The polarization-degree calculation model in this paper can simulate the degree of polarization of rough surface radiation well.(3)Considering that K-K relation cannot reflect the surface roughness,the inversion models of surface optical constants and roughness parameters are established on the basic of mathematical description of S wave reflectivity in the polarization calculation model.Having acquired the surface parameters of aluminum foil by inversion model,the optical constants are compared with literature results and the roughness was compared with actual measurement results.The results show that the model can accurately retrieve the surface optical constants and roughness parameters.(4)The polarization imaging of the rectangle and cylinder under specific environmental conditions is simulated,and the characteristics of spectral polarization imaging and the related change rules are analyzed.The results show that there is great difference in polarization imaging between curved and plane surfaces,and it is also different in temperature difference.(5)Aiming at the midcourse target of the missile,the three incident light system,including the space background radiation,the solar radiation,the earth's own radiation and the earth's reflection solar radiation,is established to explore the polarization imaging rule of the missile with different surface materials,different space target shapes and different detection bands.The infrared thermal imaging contrast results show that under the same conditions,infrared polarization characteristics of missile in space displacement process changes significantly with time,the degree of polarization of the surface edge of target is much higher than that of other parts,so that it is easier to be detected.The polarization imaging of the target with better spectral characteristics is very different in different detection bands,and this kind of target is easily detected by multi band polarization detection.Therefore,polarization detection is of high value in the field of space target recognition.