湍流内尺度对光波起伏频谱的影响

在不同湍流内尺度情况下,对大气湍流引起的光波光强闪烁和到达角起伏的时间频谱特征进行了实验研究。由于实际大气湍流的复杂性和不可控性,利用大气湍流模拟箱来生成具有不同内尺度的大气湍流实验环境。利用位置敏感探测器对光波的光强闪烁和到达角起伏进行了同时测量,并反演得到了光传输路径上的湍流内尺度。实验结果显示:湍流内尺度为2.7~5.0 mm,对应同一湍流内尺度,闪烁频谱和到达角起伏频谱在高频段以相同的幂指数关系下降,幂指数的绝对值与湍流内尺度的大小呈线性关系,随着内尺度的增大,频谱指数变化区间逐渐向低频方向移动。

Effect of turbulence inner scale on light-wave temporal spectra

The temporal spectra of scintillation and angle-of-arrival fluctuations have been studied experimentally for light-waves traveling in turbulence of different inner scales. Because of the complexity and uncontrollability of the real atmosphere, the experiment was performed with an atmospheric turbulence chamber. The scintillation and angle-of-arrival fluctuations of the propagating light-wave were simultaneously measured by a position sensitive detector, and the turbulence inner scale along the optical propagation path was derived through inversion. Experimental results show that the high frequency region of both kinds of temporal spectra obey the same power law, and the absolute value of the power exponent and the turbulence inner scale are in linear relation. With the increase of the inn