Stability margin loss due to wavefront sensor misregistration: amelioration with spatial filtering techniques

Terry J. Brennan

doi:10.1117/12.438179

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4 September 2001 Stability margin loss due to wavefront sensor misregistration: amelioration with spatial filtering techniques

Terry J. Brennan

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Proceedings Volume 4376, Laser Weapons Technology II; (2001) https://doi.org/10.1117/12.438179
Event: Aerospace/Defense Sensing, Simulation, and Controls, 2001, Orlando, FL, United States

Abstract

A phase reconstructor for an adaptive optics system depends on a model of the response of commands to the deformable mirror in the gradient sensor. Errors in this model may be due to actuator/sensor misregistration. The level of misregistration which produces closed loop instability is calculated for several systems (2 X 2, 4 X 4, and 15 X 15 subapertures). Depending on the servo law, the 15 X 15 system may be stable for misregistration up to 17% of a subaperture but loses 30 degrees of phase margin at 5%. The effects of system size, servo bandwidth, latency, and actuator slaving are illustrated. It is also shown that spatially filtering the reconstructed phase can dramatically reduce the sensitivity to misregistration.

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Terry J. Brennan "Stability margin loss due to wavefront sensor misregistration: amelioration with spatial filtering techniques", Proc. SPIE 4376, Laser Weapons Technology II, (4 September 2001); https://doi.org/10.1117/12.438179

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