1.State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China 2.Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China 3.Key Laboratory of Space Object and Debris Observation, Chinese Academy of Sciences, Nanjing 210008, China
Fund Project:Project supported by the Youth Innovation Promotion Association of CAS (id. 2018303), the National Defense Innovation Fund of the Chinese academy of sciences, China (Grant No. CXJJ-16S009), the National Natural Science Foundation of China (Grant Nos. U1231107, U1631240, 11774095, 11804099)
Received Date:27 August 2019
Accepted Date:16 October 2019
Available Online:13 December 2019
Published Online:05 January 2020
Abstract:Classical satellite laser ranging (SLR) technology based on 532 nm wavelength usually adopts low energy laser to measure cooperative objects. However, for a very weak target, such as debris and lunar reflector arrays, laser ranging system should have much stronger detection capability than the laser ranging system for traditional application. A common way to improve system detection capability is to use high energy laser. With an additional frequency doubling crystal, it is more difficult to make a high energy laser based on 532 nm than that based on 1.06 μm, which restricts the improvement of system detection capability, and also gives rise to the short lifetime, poor system stability problems. Compared with 532 nm laser, the 1.06 μm laser has many advantages of high laser energy and power, high atmospheric transmissivity, and low background noise, thereby making it an ideal substitution for the traditional 532 nm SLR system. In this paper, we comparatively analyze the above-mentiond advantages of the 1.06 μm laser and other system’s key parameters such as detector efficiency and target reflection efficiency, calculate the echo photons one can obtain, and establish a 1.06 μm laser ranging system based on the existing 532 nm SLR at Shanghai Astronomical Observatory. Owing to the using of an InGaAs single photon detector, the system turns very compact, low cost, easy-to-be-installed and has almost no additional operation complexity than the 532 nm system. With this system, the high precision 1.06 μm laser ranging for cooperative objects based on InGaAs detector is carried out for the first time in China, and a ranging for space debris 1500 km away can also be realized. The ranging experiment shows with the same laser, SLR using 1.06 μm output reaches a detection efficiency of 7 times the detection efficiency the SLR using 532 nm output reaches, and the background noise only 1/5. This approves the advantages and feasibility of 1.06 μm system, and also shows its great potential application prospects in the high precision weak target laser detection in the day and night time. This paper provides a very easy operation, high compact and low cost method for the future high precision weak target laser ranging. Keywords:satellite laser raging(SLR)/ space debris detection/ near infrared/ single photon detection
其中τ为大气单程透过率, λ为光的波长, θ为观测仰角, θzen为天顶角. 根据(1)式进行计算, 图1(a)为根据不同仰角情况下1.06 μm和532 nm的单程大气透过率情况, 图1(b)为两者单双程大气透过率比例曲线, 可见, 从模型公式上, 双程大气透过率比例在仰角20°情况下可达3倍多, 使用1.06 μm波长对提高系统效率作用显著. 图 1 (a) 1.06 μm和532 nm单程大气透过率随不同仰角变化模型曲线; (b) 1.06 μm和532 nm单双程大气透过率比随不同仰角变化的比例曲线 Figure1. (a) The curve of one-way atmospheric transmissivity at 1.06 μm and 532 nm with different elevation angles; (b) the scale curve of one-way and two-way atmospheric transmissivity at 1.06 μm and 532 nm with different elevation angles.