设计和搭建用于湍流校正的自适应光学系统时，必须考虑大气湍流波面校正所需的系统带宽。由于通常理论估计与实际的湍流情况相差很大，本文对如何进行带宽的精确测量进行了研究。通过对500 m水平距离湍流波面的大量统计，分析了湍流波面的时间功率谱密度，得出了所需要带宽(Greenwood频率)的大小，并且首次得到了带宽需求的昼夜变化规律。实验发现，所需带宽在晚上变化缓慢，围绕10~15 Hz波动；白天变化剧烈，在20~90 Hz波动。 最后，通过实验确定出了功率谱密度估计所需的采样总时间为70 s，得到的实验结果为设计和搭建更加合理的自适应光学系统提供了实验依据。

It is necessary to design an appropriate system bandwidth for an adaptive optical system to correct the atmospheric turbalence. Because the theoretical estimation for the turbulence is more different from the real atmospheric tarbulence,this paper researched the method to measure the bandwidth accurately.Through measurement of the wavefront passed through 500 m of horizontal turbulence, the phase power spectral density of turbulence wavefront was analyzed, from which the circadian variation of the bandwidth requirement was obtained for first time. It shows that the bandwidth requirement is nearly steady around 10 to 15 Hz in night time, and strongly fluctuated around 20 to 90 Hz in day time. Furthermore, it points out that the total sampling time for the estimated bandwidth must be greater than 70 s in order to acquire a more precise result. There experimental results can provide useful data for designing and can fabricate an more reasonable adaptive optical system.