Development of a Background Oriented Schlieren Based Wavefront Sensor for Aero-Optics
Development of a Background Oriented Schlieren Based Wavefront Sensor for Aero-Optics
复制标题
用于航空光学的背景导向纹影波前传感器的开发
DOI：
10.2514/6.2010-4842
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发表时间：
2010
期刊：
影响因子：
1.9
通讯作者：
B. Thurow
中科院分区：
文献类型：
--
作者：
A. Bichal;B. Thurow
背景定向纹影(BOS)成像的基本原理有助于测量湍流引起的光学波前失真。本文研究了一种基于BOS的波前传感器的初步研制。与诸如Shack-Hartmann波前传感器等竞争设备相比，基于BOS的波前传感器的优势在于能够以经济的方式测量具有潜在高空间分辨率的大口径波前。结合传感器成像功能要求的分析分析表明，该传感器能够以20微弧度的精度测量局部波前倾斜。分析发现，在成像条件下，灵敏度主要是镜头f数的函数，这使得背景可以定位在离测试段更远的地方，而镜头焦距只起到很小的作用。这些想法是通过在马赫2.0风洞中安装的锥体上进行的实验来验证的。波前测量与锥形激波密度场的解析模型所预期的失真定性一致。隧道壁面的湍流边界层和马赫波辐射也被探测到。未来的实验将使用已知的畸变源来校准测量结果。总体而言，基于BOS的波前传感器的概念被证明是波前测量的有效和可行的选择，特别是对于中到大规模环境中的气动光学研究。
The fundamental principles of Background Oriented Schlieren (BOS) imaging are conducive for the measurement of optical wavefront distortions imposed by turbulent flows. This work explores the initial development of a wavefront sensor based on BOS. The advantages of a BOS based wavefront sensor over a competing device, such as a Shack-Hartmann wavefront sensor, is the ability to measure large aperture wavefronts with potentially high spatial resolution in an economical fashion. An analytical analysis which incorporates the imaging function requirement of the sensor illustrates the ability to measure local wavefront tilts with accuracies on the order of 20 microradians. The analysis finds that under imaging conditions, sensitivity is mainly a function of the lens f-number, which allows the background to be positioned further away from the test section, with the lens focal length only playing a minor role. These ideas were tested using experiments conducted on a cone mounted in a Mach 2.0 wind tunnel. Wavefront measurements agreed qualitatively with the distortion expected from an analytical model of the conical shock’s density field. Turbulent boundary layers and Mach wave radiation from the tunnel walls were also detected. Future experiments will calibrate the measurement with a known distortion source. Overall, the concept of a BOS based wavefront sensor is shown to be a valid and viable option for wavefront measurements, particularly for aero-optics studies in medium to large-scale environments.