| Due to the influence of atmospheric turbulence,such as beam drift and phase distortion,the receiving beam wavefront distortion is caused in space laser communication system,which seriously restricts the performance of atmospheric optical communication system.Therefore,it is very important to correct and compensate the optical wavefront distortion.In this paper,the application of wavefront simulation and wavefront correction of liquid crystal spatial light modulator is discussed,and the wavefront correction of adaptive optical system is studied with deformable mirror.The main tasks are as follows:1.The wavefront simulation of liquid crystal spatial light modulator is carried out by using Labview,and an experimental platform is built for experimental research.The control algorithm for wavefront correction with deformable mirror and liquid crystal spatial light modulator is introduced.The far-field spot Steelcr s ratio and the average gray-scale energy are used as the system objective functions.The ability of two kinds of wavefront correctors to correct the wavefront distortion in the wavefront detection adaptive optics technique is analyzed on an experimental platform.2.The modulation characteristics of liquid crystal spatial light modulator are discussed.The amplitude modulation and phase modulation characteristics of the hybrid liquid crystal spatial light modulator are analyzed,and the phase modulation characteristics of the liquid crystal spatial light modulator used in the wavefront correction experiment are studied experim entally.At the same time,the phase modulation characteristics are calibrated by building the optical patlh of the Tamman Green experiment.3.The experimental system of coherent optical communication based on adaptive optical technology without wavefront detection is studied.The experiment of wavefront correction using deformable mirror and liquid crystal spatial light modulator in adaptive optical system is studied.In this paper,two kinds of wavefront correctors are analyzed and compared with each other under the external field transmission of 1300 m.The results show that the liquid crystal spatial light modulator can produce continuous smooth wavefront aberrations and can realize the wavefront simulation well.In the static wavefront correction experiment,the average gray value of the center of the spot increased from 219.8 to 1246.6 after the correction of the deformable mirror.After correction with liquid crystal spatial light modulator,the average intensity of the ring circumference increases from 382.75 to 1164.5,and the luminance concentration of the light spot is obviously improved,which is in agreement with the theoretical analysis,and the correction effect is good.Under the external field experiment,the intermediate frequency voltage difference can reach about 1.5mV before and after correction by deformable mirror,and the spatial light modulator can reach about 0.55mV,which shows that the fast response speed of deformable mirror is superior in the case of dynamic correction. |
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