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11 August 2008 Temporal phase detection of interferograms without frequency carrier
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In our Optical Metrology laboratories, we deal with the problem of demodulating temporal sequences of interferograms. These sequences of interferograms are obtained by means of optical testing of transient events using an Electronic Speckle Pattern Interferometry system (ESPI). It is well known that using Phase Stepping Interferometry techniques (PSI), one can obtain the modulated interferogram phase with at least three equally temporal phase shifted interferograms. To obtain these three (or more than three) phase shifted interferograms with a conventional ESPI array, it is necessary to have a static object under test. On the other hand, if the object under test is not static, we can make the analysis using dual-pulse subtraction ESPI, introducing a spatial frequency carrier. However, in our case, we will use a conventional ESPI technique, with a continuous laser and without a frequency carrier. Thus, as we pretend to analyze transient deformations or events without frequency carrier, we can not use the demodulation methods used in dual-pulse subtraction ESPI, nor PSI techniques because it results almost impossible to take the least amount of interferograms with the required linear phase shift (or temporal carrier) among them. To accomplish this, it will be necessary look for alternatives to demodulate temporal sequences of interferograms without a frequency carrier and without linear phase-shifting. Here, we present the groundwork aimed at demodulating sequences of interferograms without a frequency carrier, where traditional PSI techniques are unable to detect the phase correctly.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
J. C. Estrada, M. Servin, and D. Arroyo "Temporal phase detection of interferograms without frequency carrier", Proc. SPIE 7063, Interferometry XIV: Techniques and Analysis, 70631B (11 August 2008);


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