<title>Advanced methods for optical jitter suppression using acoustic acutators</title>

Abstract

The objective of the research is to investigate an effective method of using servo control through the use of a fast steering mirror and/or acoustic actuators and sensors for optical jitter suppression. The experimental testbed is built in an anechoic chamber at Duke University. Two optical benches are used to isolate metrology components from vibrating optical elements. A Helium-Neon laser and a position sensor are mounted on one optical bench and a turning flat mirror and a 3-axis fast steering mirror are on the other optical bench. External acoustic disturbances from the speaker are used to generate vibration in the optical components. A speaker housed within an enclosure and a fast steering mirror are the two allowable control actuators and external microphones are used for reference measurement, microphones/accelerometers mounted on or nearby the optical elements and the optical sensor are the three allowable control sensors in the experiment. The generalized predictive controller is used to conjugate the process of the system identification algorithm and the process of the controller design, and can be updated adaptively in the changes of the operating environment. The generalized predictive controllers are designed for each actuator and each sensor: Case 1) Fast steering mirror and position detector, Case 2) Control speaker and position detector, Case 3) Fast steering mirror and external microphones. The generalized predictive controller for all control actuators and sensors is also designed.