大气风速对大气传输光束相位特性的影响

采用功率谱反演法构建湍流相位屏,通过横向平移相位屏的方法模拟大气风速引起的湍流时间变化,进而模拟分析了包括时间进程的激光大气传输特性,从波前相位功率谱密度的角度,定量分析了大气风速引起的激光束在大气湍流中传输时的相位特性变化。在此基础上,采用影响函数模拟变形镜对畸变波前的校正作用,对激光束经大气湍流传输后的自适应校正效果进行了预估,分析了大气风速对校正效果的影响。结果表明,大气风速对边界层湍流中光束相位特性的影响很小,然而,对于自由大气湍流中的传输光束,大气风速越大,波前相位畸变程度越大,畸变波前中高频相位比例也越大;环状光束的校正效果受大气风速的影响比平顶光束更小,并且,随着环状光束阶数的增大,校正效果所受影响逐渐减小;在一定相位畸变范围内,畸变程度越大的环状光束的相位校正效果受大气风速的影响越小。

Effect of atmospheric wind speed on phase characteristics of laser beams in atmospheric turbulence

By constructing a turbulence phase screen with the method of power spectrum inversion and translating the phase screen, the temporal variations of turbulence caused by atmospheric wind speed were simulated. The propagation characteristics of laser beams in atmospheric turbulence including temporal evolution were simulated and analyzed, and the variations of phase characteristics of laser beams in atmospheric turbulence caused by atmospheric wind speed were quantitatively analyzed from the view of wavefront power spectral density. And the correction effect of deformable mirror for the distorted wavefront was simulated by using influence function. The adaptive correction effect for the distorted wavefront of laser beams propagating in atmospheric turbulence was estimated, and the influence of atmospheric wind speed on the correction effect was analyzed. The results show that, the influence of atmospheric wind speed on the phase characteristics of laser beams in boundary layer turbulence is very small, whereas for the laser beams in free layer turbulence, the higher the atmospheric wind speed, the severer the wavefront phase distortion and the larger the proportion of high frequency in distorted wavefront. The influence of atmospheric wind speed on the correction effect of annular beams is smaller than that on the correction of flat-topped beams, and the influence on the correction effect decreases gradually with increasing the beam order of annular beams. To a certain extent of distorted phase, the severer the phase distortion of annular beams, the weaker the influence of atmospheric wind speed on the correction effect.