Abstract: A computerized closed loop wavefront control system has been developed by Hughes Danbury Optical Systems (HDOS) in support of the Advanced Beam Control System (ABCS) Program. This system uses a 97 channel Litton Itek Optical Systems deformable mirror (DM) to provide accurate wavefront control. The continuous facesheet mirror has a 63 mm aperture and drivers which address each of the 97 low voltage electrostrictive actuators independently. Performance has been thoroughly tested to ensure meeting the system requirements. Facesheet stroke is 4 $mu when actuated in piston, and 2.7 $mu for a singularly driven actuator; test results indicate linear surface displacement as a function of input voltage throughout this stroke region. Hysteresis is less than 1.5% of the total stroke and an actuator's coupling to its nearest neighbor is approximately 10%. Single actuator bandwidth is virtually flat out to 1 kHz. Performance data is presented. The computerized wavefront control system is capable of accurately measuring the output wavefront and generating commands to produce the desired shape. Closed loop control has been demonstrated to produce various mirror surfaces with an accuracy of 0.020 $mu rms. Data is presented showing the control capability. !3
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