<title>Wavefront Sensing And Control Aspects In A High Energy Laser Optical Train</title>

In this paper we review the major elements of a HEL wavefront sensing and control system with particular emphasis on experimental demonstrations and hardware components developed at Lockheed Missiles & Space Company, Inc. The review concentrates on three important elements of wavefront control: wavefront sampling, wavefront sensing and active mirrors. Methods of wavefront sampling by diffraction gratings are described. Some new developments in wavefront sensing are explored. Hardware development efforts of fast steering mirrors and eage controlled deformable mirrors are described.