Hydraulic Actuators for Active Optical Systems.

Abstract : A fast response, high accuracy, compact hydraulic actuator has been developed and demonstrated for applications that require actuators providing moderate speed, high force, and large optical path length excursions, e.g., as a mirror driver in an adaptive optical system. The actuator is characterized by a -3 dB response bandwidth of 670 Hz when operated at a supply pressure of 3000 psi, and a total excursion of 42.4 micrometers, which corresponds to plus or minus 4 wavelengths of phase shift at 10.6 micrometers when used as a mirror driver. The actuator was tested in a deformable faceplate fixture that simulates nine actuator positions at a modular spacing of 2 cm (0.8 in.). Plots are given of measured mirror surface profiles and contours. A computed contour plot is given for comparison. Also included is a program for computer simulation of the actuator in a complete multichannel, multidither COAT control system.