百kHz重复频率卫星激光测距

Research on satellite laser ranging at pulse repetition frequency of 100 kHz

对卫星激光测距(Satellite Laser Ranging,SLR)回波数与重复频率、脉冲能量及功率关系进行分析,表明单位时间内相同激光回波数,重复频率越高所需激光脉冲能量和平均功率越低;同时对SLR单次测量精度及标准点数据精度进行分析,表明标准点时长内测距点数越多,SLR标准点精度越高。提出点火脉冲群与门控脉冲群收发交替的工作模式,解决超高重复频率后向散射光噪声对激光回波干扰问题。开发多缓冲区存储模式,使测量软件数据实时处理与储存效率提升4~6倍。基于中国科学院上海天文台60 cm口径SLR系统,以快速事件计时器、脉冲群生成器、低噪声单光子探测器等,采用脉冲间隔5μs、单脉冲能量80μJ的皮秒激光,收发交替脉冲群模式下实现100 kHz重复频率低轨至高轨卫星的SLR测量,近地星Hy2b标准点精度达到28.55μm,远地星Galileo218标准点精度达到136.51μm,为发展更高重频和高精度空间目标激光测距提供了有效方法。

The relationship between the number of satellite laser ranging(SLR)echoes and the repetition rate,laser pulse energy and power are analyzed,it shows that under the same laser echoes,the higher the repetition rate,the lower the laser pulse energy and laser average power are required.Meanwhile,single-shot accuracy and normal point(NP)accuracy of SLR are analyzed,it shows that the more measuring points within the NP time are,the higher the NP accuracy would be.The working mode of firing pulse trains and receiving pulse trains triggered by a fixed period range gate is proposed to solve the interference problem of laser echo caused by back-scattered laser noise with ultra-high pulse repetition frequency(PRF).The multi-buffer storage mode is developed to improve the real-time processing and storage efficiency of data in measurement software by 4-6 times.Based on the telescope aperture of 60 cm SLR in Shanghai Astronomical Observatory,CAS,the PRF of 100 kHz SLR is realized by using fast event timing,ultra-high pulse trains generator,low noise single photon detector and picosecond laser with pulse spacing of 5μs,single pulse energy of 80μJ.Measured data of satellites by the PRF of 100 kHz SLR is from low earth orbit(LEO)and high earth orbit(HEO).The NP accuracy for Hy2b satellite in LEO is 28.55μm,and that of Galileo218 satellite in HEO is 136.51μm.This study provides an effective method for higher frequency and high-accuracy space target laser ranging.