The temporal error of the adaptive optical system leads to a significant degradations in the characteristics of the system operating in the atmosphere. One of the methods for solving this problem is the use of prediction algorithms based on the analysis of the evolution of phase fluctuations. In the paper the wavefront sensor as the key element of atmospheric adaptive optical system with predictions algorithms is considered. The results of the development and testing of the Shack-Hartmann wavefront sensor providing measurements of phase fluctuations, determination of the Fried parameter and wind speed using original design solutions and software are presented. The practical and theoretical aspects of using the Shack-Harmann wavefront sensor are discussed. For it dynamic range, sensitivity and accuracy of the sensor are estimated. The influences of parameters of microlens array on range of measurements of the Shack-Harmann wavefront sensor are studied. The tests of the S-H WFS were carry out with acoustic measurements of wind speed and the structural constant of the refractive index of the atmosphere, as well as in adaptive optics system in laboratory test bench.
We describes the status of AO test bench, which is developing at the Adaptive optics Lab, V.E. Zuev Institute of Atmospheric Optics of the Siberian Branch of the Russian Academy of Sciences (IAO SB RAS), Tomsk, Russia to simulate predictive algorithms of wavefront adaptive correction. The description of the optical and mechanical design, components AO bench, and the working principle and first experimental results are presented. The current AO test bench consists of laser source, two deformable mirrors with 59 actuators and 56 mm diameter (Visionica Ltd., Russia), two tip/tilt mirrors (IAO SB RAS, Russia), Shack-Hartmann Wavefront Sensor (WFS), which we specially designed, and a science camera for the evaluation of the performance. The user derived aberrations are introduced using a one deformable mirror and corrected by another deformable mirror. The tip/tilt mirrors are used for predictive control of the low-order wavefront aberrations related such as vibrations.
The results of experimental studies of the effect of atmospheric turbulence in the adaptive optical image correction system at the Baikal Large Solar Vacuum Telescope (LSVT) are presented. To eliminate the jitter and stabilize the image on the receiver, the appropriate hardware and software system that corrects the tilts of incoming wave front with frequencies up to 1 kHz has been developed in the Laboratory of the Coherent Adaptive Optics (LCAO). To obtain digital images of high resolution, the tip-tilt adaptive system is combined with a post-detection computer processing of frames using fast 2D parallel real time algorithms. Experimental data confirm the high efficiency of the dual adaptive system for stabilizing and forming images on the LSVT.