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Robust phase unwrapping based on non-coprime fringe pattern periods for deflectometry measurements

Allgeier, Stephan; Gengenbach, Ulrich; Köhler, Bernd; Reichert, Klaus-Martin; Hagenmeyer, Veit

Abstract (englisch):
Phase-measuring deflectometry is a technique for non-contact inspection of reflective surfaces. A camera setup captures the reflection of a sine-modulated fringe pattern shifted across a screen; the location-dependent measured phase effectively encodes the screen coordinates. As the used fringe patterns are much narrower than the screen dimension, the resulting phase maps are wrapped. The number-theoretical solution uses the Chinese remainder theorem to calculate an unwrapped phase map from repeated measurements with coprime fringe widths. The technique is highly susceptible to phase noise, i.e. small deviations of the measured phase values generally lead to unwrapped phase values with large errors. We propose a modification and show how non-coprime period widths make phase unwrapping robust against phase noise. Measurements with two non-coprime fringe period widths introduce the opportunity to discriminate between “legal” measured phase value pairs, that potentially originate from noise-free measurements, and “illegal” phase value pairs, that necessarily result from noise-affected measurements. Arranged as a matrix, the legal measurements lie on distinct diagonals. ... mehr



Originalveröffentlichung
DOI: 10.1117/12.2523564
Zugehörige Institution(en) am KIT Institut für Automation und angewandte Informatik (IAI)
Publikationstyp Proceedingsbeitrag
Jahr 2019
Sprache Englisch
Identifikator ISBN: 978-1-5106-2802-1
KITopen-ID: 1000096445
HGF-Programm 43.22.03 (POF III, LK 01)
Erschienen in Automated Visual Inspection and Machine Vision III - SPIE Optical Metrology, 2019, Munich, Germany, 24-27 JUNE 2019. Ed.: J. Beyerer, F. Puente León
Veranstaltung SPIE Optical Metrology (2019), München, Deutschland, 24.06.2019 – 27.06.2019
Verlag SPIE, Bellingham (WA)
Seiten 1106103
Serie SPIE Proceedings ; 11061
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