Research On Multi-dimensional Detection Technology Of Space Target Foundation All-day Period

With the rapid development of space technology,the ability of in-orbit satellites to detect ground targets is increasingly enhanced,and the trend of space militarization is more and more obvious,which seriously affects the stability and balance of international strategy.There is an urgent need to carry out ground-based all-time detection and imaging of such satellites,and master the detailed information of their material composition,so as to provide technical support for space early warning and information countermeasures,and effectively guarantee China's space security.This paper aims at the problem that the ground-based optical system can't effectively recognize the reconnaissance satellite in the daytime due to the strong background noise,the polarization bidirectional reflection distribution function(p BRDF)modeling,the near-infrared polarization characteristics experiment and simulation analysis of typical satellite surface materials,and the sky background polarization modeling and simulation analysis are carried out,on this basis,the detection scheme of combining near infrared(1.5?1.8?m)filtering imaging technology with polarization imaging technology is proposed,can realize all-time multi-dimensional detection of space targets.The specific content is as follows:Firstly,the scattering characteristics of the target material surface were characterized by the combination of specular and volume scattering.A more perfect multi-parameter p BRDF model was established based on the microfacet model,and a formula for the expression of polarization degree of optical reflection on rough material surface was deduced.After verifying the accuracy of the model,the near-infrared polarization test of typical satellite surface materials was carried out,and the multi-parameter values of satellite surface materials were retrieved from the experimental data by using genetic algorithm,and then the polarization degree simulation curve was obtained.The experimental and simulation results show that the near-infrared polarization characteristics of different satellite surface materials have great differences,and the polarization imaging technology can effectively distinguish the target materials.Secondly,the polarization Rayleigh scattering model of sky background is established based on astronomical and horizon coordinates.Aiming at the distortion of the sky background distribution when it is vertical mapped from three-dimensional to two-dimensional,the complex spherical mapping theory is used to correctly describe the polarization distribution characteristics of the sky background theory.On this basis,the distribution law of sky background polarization characteristics is summarized and analyzed,which provides a theoretical basis for the research of sky background noise influence and imaging effect of space target ground-based near-infrared polarization imaging technology.Finally,according to the requirements of space target ground-based all-time imaging recognition,the overall scheme design of the system based on micro polarizer real-time polarization imaging technology is carried out,and the technical indicators in the scheme are studied and selected,including the selection of detection band H band(1.5?1.8?m),near-infrared filter and detector.A 1.8m aperture ground-based telescope optical system is designed.The modulation transfer function(MTF)of the system is close to the diffraction limit at the Nyquist frequency of 34 lp /mm.The simulation results show that this system scheme can meet the imaging resolution of 0.6 m at 500 km,and the limit detection ability can reach 11.13 magnitude in daytime.Under certain conditions,the target background contrast can be greatly improved,which can provide an important basis for the ground-based optical system to image and identify space targets all day.