Shape control of adaptive composite reflectors

Abstract

The topic of this paper is the quasi-static shape control of adaptive composite reflectors which are deformed by gravity at different angles of inclination, relative to the direction of the gravitational field. Two adaptive structures are presented: a plane adaptive composite mirror and a sandwich reflector with a doubly-curved reflector surface. After the description of the design aspects and the numerical simulation of both structural concepts, special emphasis is given to the description of the set-up for the verification of shape control. As the gravity-induced deformations of this structure are in the order of micrometers while the measurement range is over the full 90° of all possible states of the inclination angle, the improved Electronic Speckle Pattern Interferometry (ESPI) applying incremental phase shifting technique is used to measure the interesting out-of-plane displacement field due to acting gravity. The experimental speckle interferometric data are in good qualitative agreement with the results of the numerical FEM model.