Velocity estimation from fringe contrast using lensless Fourier transform digital holography

Urvashi Jinwal; Surya Kumar Gautam; Athira T. S.; Pramod Panchal; Dinesh N. Naik

doi:10.1117/12.2555789

1 April 2020 Velocity estimation from fringe contrast using lensless Fourier transform digital holography

Urvashi Jinwal, Surya Kumar Gautam, Athira T. S., Pramod Panchal, Dinesh N. Naik

Proceedings Volume 11352, Optics and Photonics for Advanced Dimensional Metrology; 113521L (2020) https://doi.org/10.1117/12.2555789
Event: SPIE Photonics Europe, 2020, Online Only

Abstract

Digital holography is one of the most powerful methods used in metrological applications for non-destructive testing of various components as it provides higher precision up to several nanometres at high speed. As there are many industrial applications such as gear metrology, surface tracing of planar components and so on, which involve dynamic objects, and holographic measurements on such objects is a challenging task. The interference pattern is no longer stable, resulting in low contrast and resolution of the recorded hologram thus degrading the recorded information. In this paper, lensless Fourier transform digital holography is used for analysing the interference contrast as a function of velocity for planar moving objects. Numerical simulations have been carried out to study how the size of reference source and the exposure time of camera affects the contrast of the interference pattern of a moving object. Experimentally, lensless Fourier transform holographic geometry is realised via Sagnac interferometer which provides robustness and immunity against the external vibrations during the recording. The maximum extent of velocity is estimated by analysing the variations in contrast such that there is minimal loss of information from the recorded hologram.

Conference Presentation

Citation Download Citation

Urvashi Jinwal, Surya Kumar Gautam, Athira T. S., Pramod Panchal, and Dinesh N. Naik "Velocity estimation from fringe contrast using lensless Fourier transform digital holography", Proc. SPIE 11352, Optics and Photonics for Advanced Dimensional Metrology, 113521L (1 April 2020); https://doi.org/10.1117/12.2555789

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