Fitting contrast by least square method for phase-shifting interferometry of unknown and arbitrary phase-steps under high non-uniform illumination

C. Meneses-Fabian; A. Barcelata-Pinzón

doi:10.1117/12.2519161

13 May 2019 Fitting contrast by least square method for phase-shifting interferometry of unknown and arbitrary phase-steps under high non-uniform illumination

C. Meneses-Fabian, A. Barcelata-Pinzón

Author Affiliations +

Proceedings Volume 10991, Dimensional Optical Metrology and Inspection for Practical Applications VIII; 109910F (2019) https://doi.org/10.1117/12.2519161
Event: SPIE Defense + Commercial Sensing, 2019, Baltimore, MD, United States

Abstract

This work presents a very robust and non-iterative algorithm for phase retrieval in phase-shifting interferometry of three unknown and unequal phase-steps under illumination conditions of high spatial non-uniformity. First, the background light is eliminated by subtraction of two interferograms, thereby two secondary patterns are obtained. Second, the object phase is algebraically eliminated from two secondary patterns to obtain only one equation in three unknowns: the modulation light, and the two phase-steps. Third, the square of modulation light is approximated to a polynomial of degree K, and then we demonstrate that it is possible to rewrite the equation in the form of an error function. Forth, the coefficients for the modulation approximation and the phase-steps are computed by applying the least squares method. Some advantages of this approach are its capacity to support high spatial variations in the illumination and the object phase.

Conference Presentation

Citation Download Citation

C. Meneses-Fabian and A. Barcelata-Pinzón "Fitting contrast by least square method for phase-shifting interferometry of unknown and arbitrary phase-steps under high non-uniform illumination ", Proc. SPIE 10991, Dimensional Optical Metrology and Inspection for Practical Applications VIII, 109910F (13 May 2019); https://doi.org/10.1117/12.2519161

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