M. Hattori, M. Nishimura and S. Komatsu: Real-time Adaptive Optics Using Twisted Nematic Liquid Crystal Light Modulator and Wavefront Distortion Sensor Based on Two-Dimensional Grating, Jpn. J Opt. (KOGAKU), Vol. 30 (2001) 262-269.

A new adaptive optical system is constructed with a wavefront distribution sensor based on 2-dimensional grating along with a twisted nematic liquid crystal phase modulator, and it is applied to compensate the wavefront distortion due to thermal turbulence. Instead of using conventional closed loop configuration, the phase compensator is directly driven by the conjugation signal for the input phase distortion calculated in the wavefront distribution sensor at each moment. The improved response speed of the system made the use of the twisted nematic liquid crystal phase compensator practical. Judging from the experimental results, the TN liquid crystal panel with the response time of 30ms is apparently effective for the compensation of the applied phase distortion by thermal turbulence. This study shows the feasibilty of the new approach proposed to construct a practical adaptive optics at a moderate cost.