Cao Zhaoliang, Mu Quanquan, Hu Lifa, Li Dayu, Liu Yonggang, Jin Lu, Xuan Li
State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, Jilin, China.
Opt Express. 2008 May 12;16(10):7006-13. doi: 10.1364/oe.16.007006.
To correct horizontal turbulences, a nematic liquid crystal wavefront corrector (NLC WFC) with a fast response is used. It can linearly modulate 2pi radian at a wavelength of 633 nm. The closed-loop frequency of the adaptive optics system was originally only 12 Hz. Hence, a control system using the NLC WFC was developed, graphic processing units (GPUs) were used to compute the compensated wavefront, and the driving software for the NLC WFC was optimized. With these improvements, the closed loop frequency increased up to 60 Hz. Finally, the correction of a 500-m horizontal turbulence was performed with this fast adaptive system. After the correction, the averaged peak-to-valley (PV) and root-mean-square (RMS) values of the wavefront were reduced to 0.2 lambda and 0.06 lambda, respectively. The core of a fiber bundle is also resolved with a field angle of 0.68". As the limit of the angular resolution of the telescope is 0.65", the quasi-diffraction limited image is acquired with the closed-loop correction. It is shown that the NLC WFC has the ability to correct weak turbulences.
为了校正水平湍流，使用了具有快速响应的向列型液晶波前校正器（NLC WFC）。它可以在633nm波长下线性调制2π弧度。自适应光学系统的闭环频率最初仅为12Hz。因此，开发了一种使用NLC WFC的控制系统，使用图形处理单元（GPU）来计算补偿波前，并对NLC WFC的驱动软件进行了优化。通过这些改进，闭环频率提高到了60Hz。最后，使用这个快速自适应系统对500米的水平湍流进行了校正。校正后，波前的平均峰谷（PV）值和均方根（RMS）值分别降低到了0.2λ和0.06λ。光纤束的纤芯也以0.68"的视场角得到了分辨。由于望远镜的角分辨率极限为0.65"，通过闭环校正获得了准衍射极限图像。结果表明，NLC WFC具有校正弱湍流的能力。
