Van Zandt Noah R, Spencer Mark F
Appl Opt. 2020 Feb 1;59(4):1071-1081. doi: 10.1364/AO.379972.
Adaptive-optics (AO) systems correct the optical distortions of atmospheric turbulence to improve resolution over long paths. In applications such as remote sensing, object tracking, and directed energy, the AO system's beacon is often an extended beacon reflecting off an optically rough surface. This situation produces speckle noise that can corrupt the wavefront measurements of the AO system, degrading its correction of the turbulence. This work studies the benefits of speckle mitigation via polychromatic illumination. To quantify the benefits over a wide range of conditions, this work uses a numerical wave-optics model with the split-step method for turbulence and the spectral-slicing method for polychromatic light. It assumes an AO system based on a Shack-Hartmann wavefront sensor. In addition, it includes realistic values for turbulence strength, turbulence distribution along the path, coherence length, extended-beacon size, and object motion. The results show that polychromatic speckle mitigation significantly improves AO system performance, increasing the Strehl ratio by 180% (from 0.10 to 0.28) in one case.
自适应光学（AO）系统可校正大气湍流引起的光学畸变，以提高长距离的分辨率。在遥感、目标跟踪和定向能量等应用中，AO系统的信标通常是一个从光学粗糙表面反射的扩展信标。这种情况会产生散斑噪声，可能会破坏AO系统的波前测量，降低其对湍流的校正效果。这项工作研究了通过多色照明减轻散斑的益处。为了在广泛的条件下量化这些益处，这项工作使用了一个数值波动光学模型，其中湍流采用分步方法，多色光采用光谱切片方法。它假设一个基于夏克-哈特曼波前传感器的AO系统。此外，它还包括湍流强度、沿路径的湍流分布、相干长度、扩展信标尺寸和目标运动的实际值。结果表明，多色散斑减轻显著提高了AO系统的性能，在一种情况下，斯特列尔比提高了180%（从0.10提高到0.28）。
