Liguo Wang, Lei Gong, Yaqing Li, Zhiqiang Yang, Lihong Yang, Yao Li
School of Photoelectrical Engineering, Xi'an Technological University, Xi'an, 710021, China.
Heliyon. 2023 Jan 21;9(2):e13121. doi: 10.1016/j.heliyon.2023.e13121. eCollection 2023 Feb.
Spatiotemporal correlation function is the basic characteristic of dynamic laser speckle and the basis of various applications. The correlation function of the speckle intensity from a 3D target in turbulent atmosphere is derived based on the model of random phase screen and Fresnel Kirchhoff Diffraction Formula, and a fast algorithm based on FFT is developed. The particularity of dynamic speckle in turbulence is numerically analyzed and discussed. The results show that the speckle intensity fluctuates at two independent scales both in space and time domain, which are affected by target size and atmospheric turbulence respectively. In particular, the time scale caused by turbulence is also affected by the target translating velocity and the wind direction. The theory and algorithm developed in this paper can play important roles in applications of laser speckle such as remote detection in atmospheric environment.
时空相关函数是动态激光散斑的基本特性和各种应用的基础。基于随机相位屏模型和菲涅耳-基尔霍夫衍射公式，推导了湍流大气中三维目标散斑强度的相关函数，并开发了一种基于快速傅里叶变换（FFT）的快速算法。对湍流中动态散斑的特殊性进行了数值分析和讨论。结果表明，散斑强度在空间和时间域中均在两个独立的尺度上波动，分别受目标尺寸和大气湍流的影响。特别是，由湍流引起的时间尺度还受目标平移速度和风向的影响。本文所提出的理论和算法在激光散斑的应用中，如大气环境中的远程探测，可发挥重要作用。
