1 December 1991 Application of phase-stepping speckle interferometry to shape and deformation measurement of a 3-D surface
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Abstract
Speckle pattern interferometry using phase stepping and digital processing is proposed and has been used to measure the shape and deformation of a 3D surface. A four beam arrangement, in which one beam is chosen to act as the reference beam, is described. A low cost piezo-electric translator is incorporated in the arrangement to permit the implementation of phase-stepping. Images are acquired by a CCD camera and PC based image processing system.

As well as providing 3D deformation measurements, the arrangement has also been used to determine the object shape by moving one of the illuminating beams. For the shape and deformation measurements, thirteen independent speckle patterns are acquired and processed. Phase maps are produced using a conventional 3-step technique and hence surface contours, displacements and strains can be obtained.

A speckled object-reference beam is used and has the advantage that the measurements are less sensitive to vibration and whole body motion than a smooth reference beam arrangement. A flat surface mounted in proximity to the surface under investigation acts as a reference plane and is used to improve the accuracy of the measurements by validating the phase-stepping steps and verifying geometric and sensitivity parameters.

The technique has been applied to the measurement of a cylinder under internal pressure. The experimental results are compared with conventional point measurements. The optical arrangement and experimental methodology are described. Advantages and limitations of the technique, together with sources of error and measurement uncertainties are discussed.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Brian N. Dobbins, Shi Ping He, S. Kapasi, Lewis S. Wang, B. L. Button, Xiaoping Wu, "Application of phase-stepping speckle interferometry to shape and deformation measurement of a 3-D surface", Proc. SPIE 1554, Second International Conference on Photomechanics and Speckle Metrology, (1 December 1991); doi: 10.1117/12.49527; https://doi.org/10.1117/12.49527
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