On-ground demonstration of laser-link construction for space-based detection of gravitational waves

Laser acquisition and pointing system is subject to establish a 10 6 km magnitude inter-satellite laser link with root ultra-high pointing precision of 10 nrad/ Hz (1 mHz-1 Hz) in space-based gravitational wave detection missions. For the unprecedented challenge, a dedicated laser link construction scheme with three different detectors is proposed. After initial pointing with star trackers, CMOS/CCD cameras intend to suppress the laser pointing error to 1 grad . QPDs are subsequently used to achieve the final requirement. With various detectors and technologies, the scheme need intensive verification and study. We first design and build an on-ground laser link construction experimental system, which can simulate the whole process and recreate the actual critical working condition as realistic as possible by comprehensively considering the simulation of optical system, far field beam receiving characteristics and target precision. Results are well in agreement with the requirements and confirm the scheme under realistic conditions, which have not yet been fully tested experimentally.