A Study on Tracking Echo Affected by the Bidirectional Reflection Distribution Function (BrdF) of a Target Surface
L-H. Zhang, B. Tang, L-J. Sun and X-H. Ma
The stability of the receiving echo in laser tracking was useful for keeping track of targets in their orbits. The reflected signal was affected by the reflection distributing characteristic of the target surface and laser incidence angle. In this paper the bidirectional reflection distributing function (BRDF) was used to analyse the effects of the receiving echo. The bidirectional reflection distribution of target satellite surface was obtained, it contained that the component of diffuse reflection became larger and the component of specular reflection became small as the increase of the target surface roughness. The receiving echo increased as the increase of the component of specular reflection, when the incidence angle was small. The receiving echo power decreased quickly under the bigger incidence angle. When the incidence angle was larger than 34º, the minimum receiving echo power that was computed by the BRDF was lower than the one computed by the lidar formula. At this time, the illuminating laser power should become five-times of the former one or the receiving aperture became 2.5 times of the former one, these methods could remove the effect of decreasing of the receiving echo power. The white coating of thermal control diffuse reflection material and F36 of the multi-cladding specular reflection material were used to do the experiment. The experiments results accorded with the simulation results. The white coating has a big surface roughness, the scanning angle was bigger, and the specular reflection component was small. When the incident angle was smaller than 45º, the receiving echo power that was computed by the BRDF was bigger than one computed by the lidar formula. The multi-cladding has a small surface roughness, the specular reflection component was big. There were no reflected signals ,when the incidence angle was bigger than 2º.
Keywords: Bidirectional reflection distribution function (BRDF), laser tracking, diffuse reflection, echo