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Proceedings Paper

Two-wavelength whole-field interferometry setup for thermal lens study
Author(s): Danilo M. Silva; Eduardo A. Barbosa; Niklaus U. Wetter
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Paper Abstract

In this paper we present a new approach for thermal lens analysis using a two-wavelength DSPI (Digital Speckle Pattern Interferometry) setup for wavefront sensing. The employed geometry enables the sensor to detect wavefronts with small phase differences and inherent aberrations found in induced lenses. The wavefronts was reconstructed by four-stepping fringe evaluation and branch-cut unwrapping from fringes formed onto a diffusive glass. Real-time single-exposure contour interferograms could be obtained in order to get discernible and low-spacial frequency contour fringes and obtain low-noise measurements. In our experiments we studied the thermal lens effect in a 4% Er-doped CaO-Al2O3 glass sample. The diode lasers were tuned to have a contour interval of around 120 μm. The incident pump power was longitudinally and collinearly oriented with the probe beams. Each interferogram described a spherical-like wavefront. Using the ABCD matrix formalism we obtained the induced lens dioptric power from the thermal effect for different values of absorbed pump power.

Paper Details

Date Published: 11 September 2012
PDF: 6 pages
Proc. SPIE 8413, Speckle 2012: V International Conference on Speckle Metrology, 841319 (11 September 2012); doi: 10.1117/12.978186
Show Author Affiliations
Danilo M. Silva, Instituto de Pesquisas Energéticas e Nucleares (Brazil)
Eduardo A. Barbosa, Faculdade de Tecnologia de São Paulo (Brazil)
Niklaus U. Wetter, Instituto de Pesquisas Energéticas e Nucleares (Brazil)

Published in SPIE Proceedings Vol. 8413:
Speckle 2012: V International Conference on Speckle Metrology
Ángel Fernandez Doval; Cristina Trillo, Editor(s)

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