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Proceedings Paper

Fourier transform methods applied to an optical heterodyne profilometer
Author(s): A. Beltrán-González; G. García-Torales; G. Martínez-Ponce
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Paper Abstract

In this work, theory and experiment describe the performance of a surface profile measurement device based on optical heterodyne interferometry are presented. The object and reference beams propagating through the interferometer are obtained by single-pass through an acousto-optic modulator. The diffraction orders 0 and the Doppler-shifted +1 (object and reference beams, respectively) are manipulated to propagate collinearly towards the interferometer output where a fast photodetector is placed to collect the irradiance. The modulated optical signal is Fourier transformed using a data acquisition card and RF communications software. The peak centered at the acousto-optic frequency in the power spectrum is filtered and averaged. The irregularities on the surface of the reflective sample are proportional to the height of this peak. The profile of a reflective blazed grating has been sketched by translating laterally the sample using a nanopositioning system. Experimental results are compared to the measurement done with a scanning electron microscope. There has been found a good agreement between both methods.

Paper Details

Date Published: 18 November 2013
PDF: 6 pages
Proc. SPIE 8785, 8th Iberoamerican Optics Meeting and 11th Latin American Meeting on Optics, Lasers, and Applications, 87853H (18 November 2013); doi: 10.1117/12.2025887
Show Author Affiliations
A. Beltrán-González, Univ. de Guadalajara (Mexico)
G. García-Torales, Univ. de Guadalajara (Mexico)
G. Martínez-Ponce, Ctr. de Investigaciones en Óptica, A.C. (Mexico)

Published in SPIE Proceedings Vol. 8785:
8th Iberoamerican Optics Meeting and 11th Latin American Meeting on Optics, Lasers, and Applications
Manuel Filipe P. C. Martins Costa, Editor(s)

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