High resolution phase-stepping shearography by using a 24 megapixel digital still imaging device

Awatef Rashid Al Jabri; Kazi Monowar Abedin; S.M. Mujibur Rahman

doi:10.1117/12.2657030

8 March 2023 High resolution phase-stepping shearography by using a 24 megapixel digital still imaging device

Awatef Rashid Al Jabri, Kazi Monowar Abedin, S.M. Mujibur Rahman

Proceedings Volume 12447, Quantum Sensing, Imaging, and Precision Metrology; 124470Q (2023) https://doi.org/10.1117/12.2657030
Event: SPIE Quantum West, 2023, San Francisco, California, United States

Abstract

Digital phase-stepping shearography is a modern precision measurement technique for quantifying microscopic displacement gradients and strains of an object surface by interferometric speckle techniques. The phase map of the displacement derivatives of a stressed object is generated using laser speckles in this technique. As a result, the strains of a deformed object can be directly mapped. Phase-stepping shearography is also very useful in industrial non-destructive testing (NDT). In conventional digital phase stepping shearography, a video camera of limited resolution is used for imaging the laser speckles. The maximum resolution of the video camera is only of the order of 5 Megapixels. This limits the spatial resolution for the generated shearograms and phase maps, and consequently, limits the maximum value of the deformations that can be successfully observed in a given situation. We improved the shearography technique and, in particular, performed advanced shearographic experiments with substantially higher spatial resolution than is now achievable. A 24 megapixel still digital image device (DSLR camera) and a Michelson-type shearing setup with an edgeclamped, center-loaded plate are used in this novel technique. Different phase-stepping algorithms were tested, and all of them produced shearograms satisfactory quality. This effectively increases the useful spatial resolution of phase-stepping shearography by roughly 5 times compared to the conventional method using video-rate cameras, and will also improve spatial resolution in many possible applications.

Conference Presentation

Citation Download Citation

Awatef Rashid Al Jabri, Kazi Monowar Abedin, and S.M. Mujibur Rahman "High resolution phase-stepping shearography by using a 24 megapixel digital still imaging device", Proc. SPIE 12447, Quantum Sensing, Imaging, and Precision Metrology, 124470Q (8 March 2023); https://doi.org/10.1117/12.2657030

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