[OPTICAL REVIEW Vol. 9, No. 3 (2002) 126-131]

Real-time Adaptive Optics with a Twisted Nematic Liquid Crystal Light Modulator Controlled by the Wave Front Reconstruction Sensor

Masayuki HATTORI1 and Shinichi KOMATSU1,2

1Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku, Tokyo 169-8555, Japan 2Department of Applied Physics, Waseda University, 3-4-1 Ohkubo, Shinjuku, Tokyo 169-8555, Japan

(Received November 14, 2001; Accepted February 22, 2002)

We propose adaptive optics constructed with a new principle. In this system, numerical phase reconstruction algorithm is incorporated with the Hartmann wave front sensor and the phase compensator is driven to the conjugate of the input phase distortion at each time step. The computer simulation shows a sufficient robustness and swiftness of the wave front reconstruction sensor. Then, the experimental system is configured putting special emphasis on the simplicity and feasibility of the system. A small 2-dimensional grid mask is used in the Hartmann sensor, and a twisted nematic phase modulator with a response time of 30 ms is used as the phase compensator. The control system has a simple open loop setup using a phase reconstruction algorithm. This experimental system was effective not only for static phase distortion, but also for the dynamic phase perturbation induced by a thermal convection.

Key words: adaptive optics, liquid crystal, phase sensing, phase reconstruction