26 July 1993 Holographic massively parallel array illuminator for operation in the near infrared
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Proceedings Volume 1983, 16th Congress of the International Commission for Optics: Optics as a Key to High Technology; 19836G (1993) https://doi.org/10.1117/12.2308651
Event: 16th Congress of the International Commission for Optics: Optics as a Key to High Technology, 1993, Budapest, Hungary
Abstract
Digital holographic interferometry DIM based on phase shifting technique has become an important diag- nostic tool in the quantitative experimental investigations. When this technique is applied for deformation measure- ment of the complex objects, there still are some problems to be solved. First, physical discontinuities of the sur- face of the complex objects often result in fringe discontinuities and local shadows in the interferogram. Second, when the phase variation between neighboring sampling points is more then it, the phase unwrapping problem ap- pears. Another problem is the separation of the measured object from the background. These problems have been the obstacles to the widespread application of holographic interferometry for automated quantitative analysis of the complex objects. In this paper a new evaluation technique for phase-shifted holographic interferograms is proposed and verified by experiments. We calculate both the discrete phase distribution and the intensity modulation of in- terference fringes, and generate a binary control mask by analyzing histograms and tracing local minima of the in- tensity modulation distribution. The control mask is used to identify valid and invalid areas of the discrete phase distribution in subsequent phase unwrapping and phase interpolation , and to control the path of phase unwrap- ping. The evaluation of experimentally obtained phase-shifted holographic interferograms shows that this method can be successfully applied for the processing of complex interference patterns, even if there are local shadows and discontinuities in the interferograms.
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H. C. Zhai, H. C. Zhai, } "Holographic massively parallel array illuminator for operation in the near infrared", Proc. SPIE 1983, 16th Congress of the International Commission for Optics: Optics as a Key to High Technology, 19836G (26 July 1993); doi: 10.1117/12.2308651; https://doi.org/10.1117/12.2308651
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