A 3-DOF space microvibration measurement method based on geometric optics

This paper introduces a novel micro-vibration measurement method applied to space environment based on geometrical optics, in which the position of the light spots reflected from a suspended test mass is measured with three position-sensitive detectors(PSD) and then three-degrees-of-freedom displacement of the test mass and micro-vibration is derived. We build a theoretical model of the method and constructed a micro-vibration accelerometer based on the method. We characterize the accelerometer and demonstrate it in micro-vibration environment provided by a drop tower driven by an electromagnetic launch system^[1]. The accelerometer’s measurement noise is less than 5×10^-5m/s²/Hz^1/2 at frequency band below 1Hz. In micro-vibration environment, the accelerometer performs better than a commercial quartz accelerometer (JN-06M) at frequency band below 1Hz. Since the accelerometer work stably at open-loop state in principle, it has great potential in long-term space micro-vibration measurement in space science experiments.