A high-bandwidth, high-precision, two-axis steering mirror

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A high-bandwidth, high-precision, two-axis steering mirror

Kluk, Daniel J. / Trumper, David L.

This paper focuses on the design, fabrication, assembly, and testing of a high bandwidth two-axis mirror positioner for precision optical platforms, which the authors refer to as the Advanced Fast Steering Mirror (AFSM). This novel positioner consists of a platform driven in two rotational axes by flux-steering electromagnetic actuators, and controlled via position feedback loops. The AFSM is designed for beam stabilization tasks in lithography, laser communication, lidar, and similar optical applications. The authors have experimentally demonstrated small-signal system bandwidth of 10 kHz using optical quad-cell feedback and a two-channel analog control architecture. The AFSM has a travel range of +/-3.5 mrad, and a measured angular acceleration of 105 rad/s². The work presented here grew out of the Mars Lasercomm demonstration program of 2005, in which MIT Lincoln Labs played a major development role. Fast steering mirrors (FSMs) are a critical component for optical communication technology. Their purpose is to accurately track a desired position, and sufficiently reject disturbances such that beam pointing errors are small enough to allow acquisition and tracking of optical signals over long distances. In the case of the Mars Lasercomm program, a laser beam originating from a Mars-orbiting satellite must be pointed within 400 nanoradians RMS error in order to allow communication with an earth-based detector array.