Variable-order adaptive control of a microelectromechanical steering mirror for suppression of laser beam jitter

We present an adaptive control scheme for laser-beam steering by a two-axis microelectromechanical systems (MEMS) fast steering mirror. Disturbances in the laser beam are rejected by a µ-synthesis feedback controller augmented by the adaptive control loop, which determines control gains that are optimal for the current disturbance acting on the laser beam. The variable-order adaptive controller is based on an adaptive lattice filter that implicitly identifies the disturbance statistics from real-time sensor data. Experimental results demonstrate that the adaptive controller significantly extends the disturbance-rejection bandwidth achieved by the feedback controller alone. The experimental results also illustrate the value of the variable-order capability of the adaptive controller.