天基合成孔径激光雷达成像参数分析

Parameters analysis of spaceborne synthetic aperture lidar imaging

为了评估和分析星载海洋激光雷达探测全球海洋光学参数的性能,依据激光雷达方程和蒙特卡罗模型结果模拟计算激光传输信号,开发了星载海洋激光雷达仿真模拟系统。仿真模拟系统由正向模拟、数据反演与误差分析三部分组成,能够模拟激光发射、传输和探测的全过程。根据给定的激光雷达参数,模拟了443 nm、486.1 nm和532 nm波长在地中海、印度洋、南大洋与太平洋四个典型海区的探测信号。研究结果表明,443 nm和486 nm波长的探测深度在各个海区均比较接近,并且均比532 nm更深。在给定的激光雷达参数情况下,486.1 nm波长在太平洋和南大洋的探测深度分别为120 m和70 m,在地中海和印度洋的探测深度均为约100 m。叶绿素a浓度在以上海区的探测深度分别约为80 m、50 m和70 m。

Since there is no atmosphere in space,problems such as atmospheric turbulence and atmospheric attenuation do not exist.Therefore,spaceborne Synthetic Aperture Lidar(SAL)has a better application prospect than ground-based and airborne SAL.In order to verify the feasibility of airborne SAL imaging,a spaceborne SAL imaging model was established,and the coherent accumulation time and PRF were derived.Then,a satellite orbit model was established by using the extrapolation method of the two-body motion.Next,according to the limitation of the radar antenna beam width,the antenna pattern of the lidar was calculated,and a method to obtain the maximum synthetic aperture time was proposed by using the target gain curve's 3 dB beam width.Finally,six kinds of spaceborne SAL imaging modes were established through simulation,and the imaging parameters under different modes were analyzed,which verified the feasibility of spaceborne SAL imaging.The research of this paper lays a foundation for the research of spaceborne SAL imaging algorithm.