Adaptive-optics system with liquid-crystal phase-shift interferometer.
We develop an adaptive-optics system based on a Mach-Zehnder radial shearing interferometer with liquid-crystal-device (LCD) phase-shift interferometry (PSI). Using accurate phase calibration and transient nematic driving of the LCD, the developed three-step PSI procedure can be achieved in a time of 5 ms. The proposed Mach-Zehnder radial shearing PSI method reconstructs the phase information using a digital signal processor (DSP). The DSP then computes appropriate control signals to drive a deformable mirror in such a way as to eliminate the wavefront distortion. The current adaptive-optics system is capable of suppressing low-frequency thermal disturbances with a signal-to-noise ratio improvement of more than 20 dB and a steady-state phase error of less than 0.02pi root mean square when the control loop is operated at a frequency of 30 Hz.
Chung
Cheng-Ying
CY
Department of Mechanical Engineering, National Central University, Chung-Li, Taiwan.
Cho
Keng-Chi
KC
Chang
Chih-Chiang
CC
Lin
Cheng-Hsiang
CH
Yen
Wei-Chung
WC
Chen
Shean-Jen
SJ