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Article

A New Pattern Quality Assessment Criterion and Defocusing Degree Determination of Laser Speckle Correlation Method

1
College of Physics and Optoelectronic Engineering, Shenzhen University, 3688 Nanhai Avenue, Shenzhen 518060, China
2
CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei 230027, China
*
Author to whom correspondence should be addressed.
Academic Editors: Maria Lepore and Ines Delfino
Sensors 2021, 21(14), 4728; https://doi.org/10.3390/s21144728
Received: 7 May 2021 / Revised: 7 July 2021 / Accepted: 8 July 2021 / Published: 10 July 2021
(This article belongs to the Special Issue Optical Sensors Technology and Applications)
The laser speckle correlation method has found widespread application for obtaining information from vibrating objects. However, the resolution and accuracy of the laser speckle correlation method as they relate to the defocusing degree have not been analyzed sufficiently. Furthermore, the possible methods for speckle pattern quality assessment and enhancement have not been studied. In this study, the resolution and accuracy of the laser speckle correlation method are analyzed, and it is found that they are affected by the defocusing degree and speckle pattern quality, respectively. A new speckle pattern quality criterion combining the mean intensity gradient and frequency spectrum was proposed, called CMZ. The quality of the speckle pattern is higher when the CMZ is closer to zero. The proposed criterion was verified by simulated speckle patterns and real speckle patterns with different speckle sizes, densities, and gray contrasts. In the experimental setup stage, a suitable defocusing degree can be selected based on the resolution requirement and optimal speckle size, and other experimental parameters can be determined according to the CMZ criterion. Rotation and vibration experiments verified the effectiveness of the laser speckle correlation method and confirmed the reliability of the experiment preparation based on proposed CMZ criterion. View Full-Text
Keywords: laser speckle correlation; defocusing degree; speckle pattern quality criterion; vibration measurement; rotation measurement laser speckle correlation; defocusing degree; speckle pattern quality criterion; vibration measurement; rotation measurement
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MDPI and ACS Style

Hu, W.; Sheng, Z.; Yan, K.; Miao, H.; Fu, Y. A New Pattern Quality Assessment Criterion and Defocusing Degree Determination of Laser Speckle Correlation Method. Sensors 2021, 21, 4728. https://doi.org/10.3390/s21144728

AMA Style

Hu W, Sheng Z, Yan K, Miao H, Fu Y. A New Pattern Quality Assessment Criterion and Defocusing Degree Determination of Laser Speckle Correlation Method. Sensors. 2021; 21(14):4728. https://doi.org/10.3390/s21144728

Chicago/Turabian Style

Hu, Wenxin, Zhipeng Sheng, Keyu Yan, Hong Miao, and Yu Fu. 2021. "A New Pattern Quality Assessment Criterion and Defocusing Degree Determination of Laser Speckle Correlation Method" Sensors 21, no. 14: 4728. https://doi.org/10.3390/s21144728

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