Document Type

Conference Proceeding

Conference

Two- and Three-Dimensional Methods for Inspection and Metrology VI

Publication Date

8-2008

DOI

10.1117/12.791265

City

San Diego, CA

Abstract

Measuring objects with high surface reflectivity variations (i.e., high dynamic range) is challenging for any optical method. This paper addresses a high dynamic range scanning (HDRS) technique that can measure this type of objects. It takes advantage of one merit of a phase-shifting algorithm: pixel-by-pixel phase retrieval. For each measurement, multiple shots of fringe images with different exposures are taken. And a sequence of fringe images with different overall brightness are captured: the brightest fringe images have good fringe quality for darker areas although the brighter areas may be saturated; while the darkest fringe images have good fringe quality in brighter areas although the fringes in the darker areas may be invisible. The sequence of fringe images is arranged from brighter to darker, i.e., from higher exposure to lower exposure. The final fringe images, used for phase retrieval, are produced pixel-by-pixel by choosing the brightest but the unsaturated corresponding pixel from one shot. A phase-shifting algorithm is employed to compute the phase, which can be further converted to coordinates. Our experiments demonstrate that the proposed technique can successfully measure objects with high dynamic range of surface properties.

Comments

This is a conference proceeding from Two- and Three-Dimensional Methods for Inspection and Metrology VI 7066 (2008): 1, doi:10.1117/12.791265. Posted with permission.

Copyright 2008 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

Copyright Owner

Society of Photo-Optical Instrumentation Engineers

Language

en

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