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Revista Facultad de Ingeniería Universidad de Antioquia
Print version ISSN 0120-6230
Abstract
VALDIVIESO GONZALEZ, Luis G.; GUERRERO BERMUDEZ, Jáder E. and TEPICHIN RODRIGUEZ, Eduardo. Non-linear joint transform correlator for micro-displacement measurement using speckle patterns. Rev.fac.ing.univ. Antioquia [online]. 2013, n.68, pp.20-26. ISSN 0120-6230.
This work presents a procedure for measuring displacements of tens micrometer, in one and two dimensions, based on the correlation between two speckle patterns. For this purpose, two objective speckle patterns are recorded by a digital camera -one before and one after the object has been moved- and placed in the input plane of nonlinear joint transform correlator. Nonlinear transformation of the joint power spectrum allows a sharper correlation peak and a high signal to noise ratio. The autocorrelation peak coordinates of the first pattern are set as a reference for measuring shifts of the successive cross-correlation peak. One criterion for reliable measure is proposed. Results related with different distances sample-sensor and illuminating wavelengths at 632.8 nm and 543.5 nm are presented.
Keywords : Laser speckle; micro-displacements; nonlinear joint; transform correlator.