26 February 2018 Sound recovery via intensity variations of speckle pattern pixels selected with variance-based method
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Abstract
In general, the sound waves can cause the vibration of the objects that are encountered in the traveling path. If we make a laser beam illuminate the rough surface of an object, it will be scattered into a speckle pattern that vibrates with these sound waves. Here, an efficient variance-based method is proposed to recover the sound information from speckle patterns captured by a high-speed camera. This method allows us to select the proper pixels that have large variances of the gray-value variations over time, from a small region of the speckle patterns. The gray-value variations of these pixels are summed together according to a simple model to recover the sound with a high signal-to-noise ratio. Meanwhile, our method will significantly simplify the computation compared with the traditional digital-image-correlation technique. The effectiveness of the proposed method has been verified by applying a variety of objects. The experimental results illustrate that the proposed method is robust to the quality of the speckle patterns and costs more than one-order less time to perform the same number of the speckle patterns. In our experiment, a sound signal of time duration 1.876 s is recovered from various objects with time consumption of 5.38 s only.
© 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)
Ge Zhu, Xu-Ri Yao, Peng Qiu, Waqas Mahmood, Wen-Kai Yu, Zhi-Bin Sun, Guang-Jie Zhai, Qing Zhao, "Sound recovery via intensity variations of speckle pattern pixels selected with variance-based method," Optical Engineering 57(2), 026117 (26 February 2018). https://doi.org/10.1117/1.OE.57.2.026117 . Submission: Received: 21 September 2017; Accepted: 1 February 2018
Received: 21 September 2017; Accepted: 1 February 2018; Published: 26 February 2018
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