Comparing to microwave radar, there are many advantages of Lidar including higher measure accuracy, finer time and space resolution, smaller volume, lighter mass. Lidar has become a very important method in high precision remote sensing domain in space. At home and abroad, Lidar has been made widely applied in space rendezvous and docking of spacecraft. Ranging accuracy is one of the important indicators of Lidar performance. The ranging precision of Lidar will be affected by temperature environment when used in space. In this paper, the results show that the value of rang measured becomes bigger and bigger as environment temperature increasing. When the temperature changes from 20°C to 60°C, the time delay between emitting and receiving optical signal increases 6.8 ns, which means the range measured increasing 1.02 m. This change will induce great influence to rendezvous and docking process when working at short range. Therefore, it is necessary to give a reasonable value on temperature control when Lidar working on-orbit to satisfy the indicator of ranging accuracy.
In space laser communication, optical antennas are one of the main components and the precision of optical antennas is very high. In this paper, it is based on the R-C telescope and it is carried out that the design and simulation of optical lens and supporting truss, according to the parameters of the systems. And a finite element method (FEM) was used to analyze the deformation of the optical lens. Finally, the Zernike polynomial was introduced to fit the primary mirror with a diameter of 250mm. The objective of this study is to determine whether the wave-front aberration of the primary mirror can meet the imaging quality. The results show that the deterioration of the imaging quality caused by the gravity deformation of primary and secondary mirrors. At the same time, the optical deviation of optical antenna increase with the diameter of the pupil.
Effect of temperature gradient and uniform temperature on tracking performance of reflectors in periscopic laser communication terminals was studied. Zernike polynomials on elliptical area were used to fit wave-front aberration of elliptical reflectors in periscopic laser communication terminals due to temperature distribution. RMS value of the thermal deformation, tracking error and intensity on detectors degradation at receiving terminals caused by thermal deformation were studied in inter-satellite laser communication system. From the result we can know that effect of temperature gradient is the move of peak intensity and a little degradation. The tracking error reaches 2.9μrad when temperature gradient is 14°C/m. The uniform temperature will cause variation of intensity distribution on focus plane of detectors. When the difference between uniform temperature and reference temperature is small, the astigmatism causing by thermal distortion is very important. As the difference becomes bigger, the high-order modes of Zernike polynomials become very important. The distribution of intensity becomes irregular and the area is very big. This will reduce the tracking performance of detectors. This work will contribute to the thermal control of elliptical reflectors in periscopic laser communication terminals on satellites in orbit.