Anand Vijayakumar, Bhattacharya Shanti, Rosen Joseph
Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC, 3122, Australia.
Sci Rep. 2019 Nov 5;9(1):16035. doi: 10.1038/s41598-019-52394-0.
Speckle correlation based optical levers (SC-OptLev) possess attractive characteristics suitable for sensing small changes in the angular orientations of surfaces. In this study, we propose and demonstrate a spatial multiplexing technique for improving the dynamic range of SC-OptLev. When the surface is in its initial position, a synthetic speckle intensity pattern, larger than the area of the image sensor is created by transversely shifting the image sensor and recording different sections of a larger speckle pattern. Then, the acquired images are stitched together by a computer program into one relatively large synthetic speckle pattern. Following the calibration stage, the synthetic speckle intensity pattern is used to sense changes in the surface's angular orientation. The surface is monitored in real-time by recording part of the speckle pattern which lies within the sensor area. Next, the recorded speckle pattern is cross-correlated with the synthetic speckle pattern in the computer. The resulting shift of the correlation peak indicates the angular orientations of the reflective surface under test. This spatial-multiplexing technique enables sensing changes in the angular orientation of the surface beyond the limit imposed by the physical size of the image sensor.
基于散斑相关性的光学杠杆（SC-OptLev）具有吸引人的特性，适用于检测表面角度取向的微小变化。在本研究中，我们提出并演示了一种用于提高SC-OptLev动态范围的空间复用技术。当表面处于其初始位置时，通过横向移动图像传感器并记录较大散斑图案的不同部分，创建一个大于图像传感器面积的合成散斑强度图案。然后，通过计算机程序将采集到的图像拼接在一起，形成一个相对较大的合成散斑图案。在校准阶段之后，使用合成散斑强度图案来检测表面角度取向的变化。通过记录位于传感器区域内的部分散斑图案来实时监测表面。接下来，在计算机中将记录的散斑图案与合成散斑图案进行互相关。相关峰的最终偏移指示被测反射表面的角度取向。这种空间复用技术能够检测表面角度取向的变化，超出图像传感器物理尺寸所施加的限制。
