High-Performance Motion Parameter Measurement Based on Optical Phase Locking and Multi-Signal Combination

In space missions and space science research, measuring the distance and motion parameters of long-distance targets with high accuracy is a hot and difficult research topic. To this end, we propose a method for measuring target distance and motion parameters based on continuous laser phase measurement and control. The method measures the distance to the target by the phase delay of the amplitude-modulated signal and the linear velocity of the target by the actuation frequency in an active optical phase-compensated control system. An experimental demonstration is performed via a hybrid fiber-space link consisting of 101 km of optical fiber and 7 m of free space with a corner-cube retroreflector fixed on a one-dimensional linear stage. Over an averaging time of 4 s, a measurement error of 4.6 μm/s was obtained for the target's linear velocity. The system is capable of continuously tracking the target's motion range, with a distance measurement error of 26 μm.