Innovative optical power detection array system for relative positioning of inner-formation flying system

The Inner-formation flying system (IFFS) is conceived to feature a spherical proof mass falling freely within a large cavity for space gravity detection, of which first application focuses on the Earth's gravity field recovery. For the IFFS, it is the relative position of the proof mass to its surrounding cavity that is feedback into thrusters for tracking control, even as part of data to detect gravity. Since the demonstration and verification of demanding technologies using small satellite platforms is a very sensible choice prior to detection mission, an optical power detection array system (OPDAS) is proposed to measure the relative position with advantages of low cost and high adaptability. Besides that, its large dynamic range can reduce the requirement for satellite platform and releasing mechanism, which is also an attracting trait for small satellite application. The concept of the OPDAS is firstly presented, followed by the algorithm to position the proof mass. Then the radiation pressure caused by the measuring beam is modeled, and its disturbance on the proof mass is simulated. The experimental system to test the performance of a prototype of the OPDAS is established, and the preliminary results show that a precision of less than 0.4 mm across a dynamic range of several centimeters can be reached by the prototype of the OPDAS.