THEORY AND LABORATORY DEMONSTRATIONS ON THE USE OF A NEMATIC LIQUID-CRYSTAL PHASE MODULATOR FOR CONTROLLED TURBULENCE GENERATION AND ADAPTIVE OPTICS

We discuss the use of liquid-crystal phase modulators (LCPM's) both as a repeatable disturbance test source and as an adaptive optics correc tor. LCPM's have the potential to induce controlled, repeatable, dynam ic aberrations into optical systems at low cost, low complexity, and h igh flexibility. Because they are programmable and can be operated as transmissive elements, they can easily be inserted into the optical pa th of an adaptive optics system and used to generate a disturbance tes t source. When used as wave-front correctors they act as a piston-only segmented mirror and have a number of advantages. These include low o perating power requirements, relatively low cost, and compact size. La boratory experiments with a Meadowlark LCPM are presented. We first de scribe use of the LCPM as a repeatable disturbance generator for testi ng adaptive optics systems. We then describe a closed-loop adaptive op tics system using the LCPM as the wave-front corrector. The adaptive o ptics system includes a Shack-Hartmann wave-front sensor operated with a zonal control algorithm. (C) 1998 Optical Society of America.