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Improving optical phase acqusition by numerical refocusing of pulsed TV interferograms
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Fluid and Experimental Mechanics.
2004 (English)In: Proceedings of ICEM 12, 2004Conference paper (Refereed)
Abstract [en]

In optical measurement situations where holographic interferometry is used the optical phase information maybe poor because of too large object deformation. The speckle pattern displacement must be less than the specklesize in the image plane to obtain high contrast fringes. A phase object that is out of focus in a laser speckle fieldmay give large speckle displacements in comparison to the situation where no phase object is present. Acombination of pulsed TV holography, digital speckle photography and a numerical refocusing technique isshown to improve the optical phase information. A flow of helium gas has been used as a test object. When thegas is out of focus an interferogram of low contrast fringes is obtained, but after refocusing high contrast fringesare obtained. The phase gradients may also be determined from the improved phase data. These phase gradientsare compared to the ones obtained in another way from two speckle displacement fields in two different imagingplanes after numerical refocusing of the speckle fields. The two phase gradients are similar

Place, publisher, year, edition, pages
Research subject
Experimental Mechanics
URN: urn:nbn:se:ltu:diva-29390Local ID: 2dcd4350-bb56-11db-b560-000ea68e967bOAI: diva2:1002614
International Conference on Experimental Mechanics : 29/08/2004 - 02/09/2004
Godkänd; 2004; 20061026 (cira)Available from: 2016-09-30 Created: 2016-09-30Bibliographically approved

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Johansson, Eva-LenaBenckert, LarsSjödahl, Mikael
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