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To decrease the influence of defocus on liquid crystal adaptive optics system,improve the imaging quality,a mechanism for defocus compensate has been designed.The mechanism was based on liquid lens,which can change the focal length continuously without any moving part.In order to design the adjust mechanism reasonably,calculation have been taken on the relationship between the rotation angle of the outer ring and the deflection of film center.Then 0.2 diopter is choosen as the division value.The parameters of the mechanism were based on relationship between the rotation angle of the outer ring with deflection of film center and the division value.It shows a good performance in liquid crystal adaptive optics system.

When atmospheric turbulence coherence length r0 is measured by traditional Differential Image Motion Monitor(DIMM) method,it is difficult to obtain a stable r0 value due to limitation of light spot pairs.Therefore,this paper proposes a statistical method to increase the statistical number of light spot pairs from one on a wavefront to twelve aligned in a square,and completes the statistics on a SHWFS light spot array captured by the Shack-Hartmann wavefront detector.The method spatially increases the statistical number of samplings and the spatial symmetry of r0 measurement,so it decreases the statistical time greatly.The experiments show that only three hundred of wavefront samples gotten in 300 ms are enough to obtain the r0 with a variation less than 3%.The presented method solves the large error problem in the traditional r0 measurement for long time,and has contributed to the improvement of imaging accuracy of adaptive optical systems for ground-based telescopes

Advances in Liquid Crystal Adaptive Optical Systems(LC AOS) are described for Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences(CIOMP,CAS) in this paper.For two bottlenecks of low energy utilization ratio and slow correction frequency in LC AOS problems,a series of effective methods are presented by the LC AOS working group.The low energy utilization ratio has been improved from 5% to 85%,which is similar to that of the deformable mirror based AOSs.Furthermore,the correction frequency of the LC AOS is also greatly improved from 5 Hz to 140 Hz,which is closed to the ability of correction for atmospheric turbulence.According to these research results,two LC AOSs which correspond to a 2.16 meter Telescope(located at Xinglong Station of Beijing Astronomical Observatory) and a 1.2 meter telescope(located at CIOMP,CAS) are designed to correct the stars.Obtained results show that the resolution ability of the star for the 1.2 meter telescope is up to 3 times of the diffraction limitation.

Three types of LC materials with isothiocyanate tolane group were prepared via couple and electronation reaction.These LCs exhibit a high birefringence,and the Δn increased with conjugation length of π-electron,the maximal value among these LCs was 0.576.When these LCs were mixed in the commercial alkyne LCs respectively,the response performance of the device could be improved.These data demonstrates that the isothiocyanate tolane LCs have high Δn and low rotational viscosity,which can be used in the device of LC spatial modulator.