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Measuring photoelastic dispersion coefficients in material samples with digital holography
Registro en:
10.1117/12.2544874
0000-0002-9379-9530
Autor
SILVA, SIDNEY L. da
PRADO, FELIPE M.
TOFFOLI, DANIEL J.
WETTER, NIKLAUS U.
SPIE PHOTONICS WEST; SPIE OPTO
Resumen
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. Funda????o de Amparo ?? Pesquisa do Estado de S??o Paulo (FAPESP) FAPESP: 19/23700-4