Development of a Hexapod Laser-based Metrology System for Finer Optical Beam Pointing Control

Free-Space Optical Communications requires stable and precise pointing on spacecraft to maintain optimal operating condition. One technology to achieve high precision pointing and steering for imaging or laser communication payload in the presence of vibrations is to make use of a Stewart platform with active struts. At the Spacecraft Research and Design Center (SRDC) of Naval Postgraduate School (NPS), a hexapod with voice coil actuators is equipped with in line accelerometers to perform the tasks of vibration isolation. For the tasks of pointing for optical payload, we adopted the approach of external measurement system, which provides directly the position and orientation information of the hexapod top platform. A laser metrology system, composed of three pairs of laser diodes and detectors, is design and fabricated at NPS. In this paper we document its development process, which includes the design, analysis, inspection and preliminary calibration effort. I