Experimental studies of a deformable-mirror adaptive optical system*

The measured characteristics of two different deformable mirror designs are presented. Each mirror is uncooled and has 37 piezoelectric actuators. The mirrors have comparable frequency response usable to over 20 kHz, but possess quite different actuator influence functions. One exhibits an exp(−αr1.5) characteristic and the other has an exp(−γr2.5) characteristic. The latter mirror is used in an 18-channel multidither adaptive optical system to perform both phase dither and phase correction functions. The measured characteristics of this system's performance include a 2 ms convergence time and effective turbulence compensation. Evidence is presented of "2Nπ" servo ambiguities, a behavior which reduces an adaptive system's overall phase compensation performance. The performance of the deformable mirror adaptive system is compared to an equivalent segmented (piston) mirror system.