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Proceedings Paper

Measuring photoelastic dispersion coefficients in material samples with digital holography
Author(s): Sidney Leal da Silva; Felipe Maia Prado; Daniel José Toffoli; Niklaus Ursus Wetter
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Paper Abstract

Polarized Digital Holography (PHD) is a fast and efficient tool for analyzing mechanical effects in materials. Especially when the task requires non-invasive techniques that do not damage the material in study, the use of PHD has great perspectives. The most common methods of digital reconstruction use the convolution theory to discretize the Huygens- Fresnel integral. When external stresses are applied to photoelastic materials, the relationship between these stresses and phase differences observed by polarization holography is an intrinsic characteristic of the material called the photoelastic dispersion coefficient. In photoelasticity, this coefficient depends on the wavelength. By using PHD the authors show in the present paper that the photoelastic dispersion coefficient also depends on the wavelength in Holography. A Mach- Zehnder interferometer, modified with the inclusion of linear polarizers, was built to verify this effect in a sample of photoelastic material. In this set-up, two coherent light sources with different wavelengths were used. For the analysis, a digital method was created that correlated the mean stresses differences on the photoelastic material sample and the mean phases differences at each distinct wavelength.

Paper Details

Date Published: 21 February 2020
PDF: 7 pages
Proc. SPIE 11306, Practical Holography XXXIV: Displays, Materials, and Applications, 113060P (21 February 2020); doi: 10.1117/12.2544874
Show Author Affiliations
Sidney Leal da Silva, Optics and Applications Group (Brazil)
Felipe Maia Prado, Optics and Applications Group (Brazil)
Daniel José Toffoli, Optics and Applications Group (Brazil)
Niklaus Ursus Wetter, Lasers and Applications Ctr. (Brazil)

Published in SPIE Proceedings Vol. 11306:
Practical Holography XXXIV: Displays, Materials, and Applications
Hans I. Bjelkhagen, Editor(s)

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