Testing of a Magneto-Strictive Actuator for Adaptive Optics

We have previously proposed the use of commercially available actuators and displacement sensors for use in the control of large deformable secondary mirrors. We have identified the magneto-strictive (MS) actuator as a promising candidate based on manufacturer's specifications for stroke, power consumption, and service life. We have identified both capacitive and eddy-current displacement sensors as possible choices for completing the required control loop around the actuators. The purpose of the tests described here was to characterize the performance of a MS actuator in terms of hysteresis, linearity, power consumption, heat dissipation, and frequency response, and to confirm the manufacturer's specifications for longevity. The purpose of the sensor testing was to compare their performance in terms of frequency response and packaging constraints. Results of the testing program are presented.