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Optical Engineering

Two-dimensional average contrast analysis of the joint Fourier spectrum under rotation of an input object
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Paper Abstract

We present a detailed study of the intensity variations of the joint Fourier spectrum of two input objects when one of them is rotated while the other remains fixed by determining the 2-D average contrast of the spectrum as a function of the angle of rotation. The contrast is found to be object dependent, decreases rapidly for small rotations, and has an almost flat response for larger rotations. We explain this behavior in both theoretical and numerical ways for two simple rectangular objects and only numerically using the fast Fourier transform, for binary and grayscale test objects whose analog rotations are acquired with an optomechanical system that uses a high-precision rotatory stage. As an application of the 2-D average contrast analysis a pair of similar cross section images of a biological organ are used, to obtain the lowest rotation angle between them, and as a consequence a quantitative aligning method for fine angular movements is presented that uses a 2f optical-digital coherent processor to obtain the Fourier transform of the input objects. Experimental results are presented.

Paper Details

Date Published: 1 December 2002
PDF: 9 pages
Opt. Eng. 41(12) doi: 10.1117/1.1518676
Published in: Optical Engineering Volume 41, Issue 12
Show Author Affiliations
Alfonso Padilla-Vivanco, Instituto Nacional de Astrofisica Optica y Electronica (Mexico)
Gonzalo Urcid-Serrano, Instituto Nacional de Astrofisica Optica y Electronica (Mexico)
Javier Baez-Rojas, Instituto Nacional de Astrofisica Optica y Electronica (Mexico)
Alejandro Cornejo-Rodriguez, Instituto Nacional de Astrofisica Optica y Electronica (Mexico)


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