自适应光学系统测试中大气湍流的时域模拟

Temporal simulation of atmospheric turbulence during adaptive optics system testing

建立了大气湍流模拟的时域模型,用于在自适应光学系统的测试中模拟大气湍流的时域变化。讨论了时域模型下随机相位屏平滑帧数和刷新频率与平均风速的关系。结果表明:对表征随机波前的随机相位屏进行时域平滑可使随机波前的变化更符合大气湍流对入射波前连续平滑渐变的影响;随机相位屏的平滑帧数仅与系统口径和大气相干长度相关,而与风速无关;随机相位屏的刷新频率与平均风速成正比,平滑后的刷新频率还与平滑帧数成正比。最后,构造了一套大气湍流模拟装置,应用功率谱分析法对时域模型的有效性进行了验证。

A temporal model was proposed for simulating the atmospheric turbulence varying with the time in the adaptive optics system testing. The relationship between the number of interpolated frames for the random phase screen, refurbish frequency and the mean wind speed was analyzed. The analysis result demonstrates that it is necessary to smooth the random phase screen for characterizing the temporal gradual variation of the random wavefront in order to make the change of the random wavefront better aligned with the influence of at- mospheric turbulence on continuous smoothing gradients of incident wavefront. The interpolated frames of the random phase screen is only related to the aperture diameter and the atmospheric coherence length, but not re- lated to the wind speed, and the refurbish frequency of the random phase screen increases with the mean wind speed, and the refurbish frequency smoothed increases with the number of interpolated frames. A atmospheric turbulence simulator was constructed in laboratory and the analysis of the power spectrum density of experimen- tal result demonstrates that temporal model of the atmospheric turbulence simulation is valid.