平顶光束通过湍流大气传输的光谱特性

采用Rytov相位结构函数二次近似的方法,推导出了平顶光束在湍流大气中的光谱传输方程,详细研究了其光谱特性,并给出了合理的物理解释。研究表明,轴上点光谱为蓝移,随着离轴距离的增大,光谱由蓝移逐渐变为红移,轴外点存在多阶光谱跃变现象。随着湍流的增强,光谱位移量和光谱跃变量减小、光谱跃变现象消失。特别分析了平顶光束与高斯谢尔模型(GSM)光束通过湍流大气传输的光谱跃变之间存在的差异。

Spectral Properties of Flat-Topped Beams Propagating through Atmospheric Turbulence

The spectral propagation equation of flat-topped beams propagating through atmospheric turbulence is derived by using the quadratic approximation of the Rytov's phase structure function.The spectral properties are studied in detail,and reasonable physical explanations are also given.It is shown that the on-axis spectrum is blue-shifted,the off-axis spectrum becomes red-shifted,and multi-order spectral transition will appear with the increase of transverse coordinate.Furthermore,the spectral shift and the transition of the spectral shift decrease with the increase of turbulence,and the spectral transition gradually disappears when the turbulence is strong enough.Specially,the behavior of the spectral transition of flat-topped beams in turbulence is very different from that of Gauss-Schell-model(GSM) beams,and the difference is discussed.