
Proceedings Paper
Robust signal evaluation for Chromatic Confocal Spectral InterferometryFormat | Member Price | Non-Member Price |
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Paper Abstract
The hybrid measurement principle Chromatic Confocal Spectral Interferometry combines Spectral Interferometry
with Chromatic Confocal Microscopy and therefore benefits from their respective advantages. Our actual
demonstrator setup enables an axial measurement range up to 100 μm with resolution up to 5 nm depending on
the employed evaluation method and the characteristics of the object’s surface. On structured surfaces, lateral
features down to 1 μm can be measured. As the sensor raw signal consists of a Spectral Interferometry type
wavelet modulated by a confocal envelope, two classes of evaluation methods working on the phasing or the
position of the envelope are employed. Even though both of these information channels are subject to their
respective problems, we show that a proper combination of the individual methods leads to a robust signal
evaluation. In particular, we show that typical artifacts on curved surfaces, that are known from Chromatic
Confocal Microscopy, are minimized or completely removed by taking the phasing of the Spectral Interferometry
wavelet into consideration. At the same time the problem of determining the right fringe order of the Spectral
Interferometry signal at surface discontinuities can be solved by evaluation of the confocal envelope. We present
here a first approach using a contrast threshold on the signal and a median referencing for trusted sections of the
analysed topography, which yields a reduction of artifacts in a submicron range on steep gradients, discontinuous
specimen or curved mirror-like surfaces.
Paper Details
Date Published: 13 May 2013
PDF: 8 pages
Proc. SPIE 8788, Optical Measurement Systems for Industrial Inspection VIII, 87880W (13 May 2013); doi: 10.1117/12.2020558
Published in SPIE Proceedings Vol. 8788:
Optical Measurement Systems for Industrial Inspection VIII
Peter H. Lehmann; Wolfgang Osten; Armando Albertazzi, Editor(s)
PDF: 8 pages
Proc. SPIE 8788, Optical Measurement Systems for Industrial Inspection VIII, 87880W (13 May 2013); doi: 10.1117/12.2020558
Show Author Affiliations
Tobias Boettcher, Univ. Stuttgart (Germany)
Wolfram Lyda, Univ. Stuttgart (Germany)
Marc Gronle, Univ. Stuttgart (Germany)
Wolfram Lyda, Univ. Stuttgart (Germany)
Marc Gronle, Univ. Stuttgart (Germany)
Published in SPIE Proceedings Vol. 8788:
Optical Measurement Systems for Industrial Inspection VIII
Peter H. Lehmann; Wolfgang Osten; Armando Albertazzi, Editor(s)
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