Open AccessThree Gaussian beam interferometric profilometer applied to the characterization of an optical flat
Author(s) -
Lorenzo Juárez P.,
Moisés Cywiak,
Manuel Servı́n,
J. Mauricio Flores
Publication year - 2007
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.15.005277
Subject(s) - optics , profilometer , interferometry , reference beam , beam (structure) , photodetector , light beam , materials science , signal (programming language) , gaussian beam , diffraction , surface roughness , physics , computer science , composite material , programming language
A three-beam scanning optical interferometric microscopic technique applied to roughness characterization of optical flats is described. The technique is based on the heterodinization of three coherent optical beams. One of the beams, the probe beam, is focused on the surface under test. A second beam is obtained after being reflected by a reference surface. Finally, the last beam consists of one of the first orders of diffraction that emerges of a Bragg-cell. The three beams are coherently added at the sensitive surface of a photodetector that integrates the overall intensity of the beams. We show analytically that, the electrical signal at the output of the photodetector, is a time-varying signal whose amplitude is proportional to the surface local vertical height. We characterize experimentally the frequency response of the system by measuring the profile of three different gratings. We show measurements of the roughness of an optical flat processed by means of the frequency response of the system.