Using a digital still camera for shearography: preliminary experiments and observations

Abedin, Kazi Monowar; Jabri, Awatif Rashid Al; Al-Shidhani, Saleh Said; Rahman, Syed Ajijur

doi:10.1117/12.2524833

Cited by 2 publications

(2 citation statements)

References 11 publications

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“…We generated subtraction-mode shearograms of a test object using a digital single-lens reflex camera (DSLR) in prior work [7]. There was no phase-stepping, and the spatial resolution of the subtraction-mode shearograms created was limited due to a camera issue.…”

Section: Introductionmentioning

confidence: 99%

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

Jabri

Abedin²,

Rahman³

2023

Quantum Sensing, Imaging, and Precision Metrology

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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.

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Section: Introductionmentioning

confidence: 99%

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

Jabri

Abedin²,

Rahman³

2023

Quantum Sensing, Imaging, and Precision Metrology

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show abstract

“…In the present paper, we present a novel and unconventional method of performing digital phase-stepping shearography with high-resolution still imaging devices. Previously, we used an 18 megapixel digital single-lens reflex camera (DSLR) to generate subtractionmode shearograms of a test object [11]. No phase-stepping was performed, and an inherent limitation of the camera (discussed later) limited the spatial resolution of the subtractionmode shearograms generated.…”

Section: Introductionmentioning

confidence: 99%

High Spatial-Resolution Digital Phase-Stepping Shearography

2021

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Digital phase-stepping shearography is a speckle interferometric technique that uses laser speckles to generate the phase map of the displacement derivatives of a stressed object, and hence can map the stresses of a deformed object directly. Conventional digital phase-stepping shearography relies on the use of video cameras of relatively lower resolution, in the order of 5 megapixels or lower, operating at a video rate. In the present work, we propose a novel method of performing high spatial resolution phase stepping shearography. This method uses a 24 megapixel still digital imaging device (DSLR camera) and a Michelson-type shearing arrangement with an edge-clamped, center-loaded plate. Different phase-stepping algorithms were used, and all successfully generated shearograms. The system enabled extremely high-resolution phase maps to be generated from relatively large deformations applied to the test plate. Quantitative comparison of the maximum achieved spatial resolution is made with the video-rate cameras used in conventional shearography. By switching from conventional (video) imaging methods to still imaging methods, significantly higher spatial resolution (by about 5 times) can be achieved in actual phase-stepping shearography, which is of great usefulness in industrial non-destructive testing (NDT).

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Using a digital still camera for shearography: preliminary experiments and observations

Cited by 2 publications

References 11 publications

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

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

High Spatial-Resolution Digital Phase-Stepping Shearography

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