Pixel-wise Amplitude Distribution Evaluation in Time Average Digital Holography
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Date
2019-12
Journal Title
Journal ISSN
Volume Title
Publisher
IOP PUBLISHING LTD
Abstract
This article introduces a new holographic method for harmonic vibration measurement. The method called time average sweeping digital holography (TASDH) is based on the continuous shift of fringe pattern described by Bessel function over the object surface. The shift is done by phase modulation in one arm of holographic interferometer. Such temporal phase sweeping allows for evaluation of the vibration amplitude value independently in each pixel by application of intensity values cross-correlation of steady state and oscillating object. Main advantage of proposed technique with respect to other methods of digital holographic vibration is its ability to measure the amplitude of vibration without the risk of interference order mismatch. Thanks to above mentioned properties, the method allows measurement of amplitude modes with high slopes or discontinuous surfaces as well as partially shaded objects. The method was experimentally tested by measuring the bending beam cantilever. The standard deviation of the measured noise is below nanometer.