Optical Metrology System for Radar Phase Correction on Large Flexible Structure

In aerospace applications there is an increasing interest in metrology systems. Metrology systems are used in applications such as wave front correction and formation flying, for measuring deployable structure deformation/oscillations, and as the crude stage for interferometer missions. In this paper we describe a concept for a metrology system. The metrology system concept will be able to determine the Cartesian (x,y,z) coordinates of 100+ fiducials to an accuracy of 1 mm with an update rate of 10 Hz. Considerable deployment uncertainty can be accepted. The system operates by laser illuminated fiducials feed through optical fibers. One fiducial is illuminated at a time. A camera reads the transverse position of the fiducial, and the distance to the fiducial is determined by modulating the laser light and measuring a phase difference. The inertial orientation of the structure is measured by imaging the stars. A metrology system as described is essential to a radar antenna on a large flexible structure.