MOE Key Laboratory of TianQin Mission， TianQin Research Center for Gravitational Physics & School of Physics and Astronomy， Frontiers Science Center for TianQin， Gravitational Wave Research Center of CNSA， Sun Yat-sen University （Zhuhai Campus）， Zhuhai 519082， China.
Supported by the National Natural Science Foundation of China （12033009）
In order to analyze the satellite laser ranging （SLR） detection capability of the TianQin Laser Ranging Station， the laser energy （average power） is set as 0.15mJ （0.015W）， 0.4mJ （0.04W） and 4mJ （0.4W）， respectively， to conduct laser ranging experiments on synchronous orbit satellites qzs2， compass i3 and compass i5 at night and daytime. Theoretically， the background noise of daytime skylight is analyzed， the effective echo rate of SLR under different average power conditions is calculated. Finally the impact of average power on SLR detection capability is particularly analyzed. In the experiment， the pitch angle of the telescope is fixed （E=50°）， and the skylight background noise intensity is measured by rotating the telescope at different points. A superconducting nanowire single photon detector （SNSPD） arrays with a detection efficiency of 60% （@1064nm） is used， and background noise is suppressed by spatial filtering， temporal filtering and spectral filtering. Using 0.4mJ （0.04W） energy to perform laser ranging on the synchronous satellite in the daytime. Using 0.15mJ （0.015W） energy to perform laser ranging on the synchronous satellite at night. The Tianqin Laser Ranging Station has the capability of conventional SLR throughout the day and night， which will lay the foundation for the full-time laser ranging of the Tianqin plan gravitational wave detection satellite in the future.