TANG Rufeng, LI Zhulian, and LI Yuqiang, from the Applied Astronomy Group of Yunnan Observatories, Chinese Academy of Sciences, obtained the photometric information of space target by analyzing the "noise" data of the laser ranging experiments, innovatively using the superconducting nanowire single-photon detector (SNSPD) array to the space debris laser ranging. The results of this research have been published on journal Optics Letters. 

In 2017, a space-debris laser ranging system with a four-element SNSPD array and the high power laser generator is built by Yunnan Observatories in China (Fig. 1). The SNSPD array shows good performance with high quantum efficiency, low dark noise, and short recovery time. During the ranging experiments, the detector works in a freely detecting state. It can detect photons not only of the laser echo, but also of the sunlight reflected by the target.

It is the characteristics of high quantum efficiency and low dark noise of the SNSPD array that makes it possible for the researchers to obtain the high time resolution light curve of the target by analyzing and processing the background light data. By further processing the light curve of some targets, the rotation information of the target is obtained. On the basis of a laser ranging system using SNSPD, the simultaneous measurement of the laser ranging and light curves of some space targets without any additional equipment is realized.

The high-resolution light curves of artificial space targets is obtained by photon counting based on the laser ranging system, which expanded the application of SNSPD and enriched the means of spatial targets monitoring.

fig.1 Laser ranging system based on SNSPD（image by Tang Rufeng) 

Contact: 

TANG Rufeng

Email:tangrf@ynao.ac.cn

Applied Astronomy Group of Yunnan Observatories, CAS