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Proceedings Paper

Novel chromatic confocal differential interference contrast prototype
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Paper Abstract

By combining classic differential interference contrast (DIC) with the chromatic confocal principle, we show that phaseshifting calibration can be avoided in DIC by using spectral information induced by the investigated sample. The created spectral fringe can be further used to unwrap the phase. This unwrapping is limited by the spectral resolution of the spectrometer. Therefore, the depth-difference around a single measurement point can be determined instantaneously. To reconstruct the depth profile, the integration of a depth-gradient is necessary. By combining the depth information of the chromatic confocal carrier signal with the differential depth information of the carried DIC signal, the accumulation of measurement uncertainty can be reduced. To our best knowledge, the proposed chromatic confocal differential interference contrast (CCDIC) is a novel profile reconstruction principle. To verify the feasibility of the CCDIC, a prototype probe with an adjustable shear and phase has been developed. Preliminary experiments achieve sub-micrometer depth resolution. A current challenge requiring further work is the stable unwrapping of the phase-difference by spectral frequencies.

Paper Details

Date Published: 21 June 2019
PDF: 9 pages
Proc. SPIE 11056, Optical Measurement Systems for Industrial Inspection XI, 1105611 (21 June 2019); doi: 10.1117/12.2527854
Show Author Affiliations
Johannes Belkner, National Taiwan Univ. (Taiwan)
Technische Univ. Ilmenau (Germany)
Hsiu-Wen Liu, National Taiwan Univ. (Taiwan)
Eberhard Manske, Technische Univ. Ilmenau (Germany)
Liang-Chia Chen, National Taiwan Univ. (Taiwan)

Published in SPIE Proceedings Vol. 11056:
Optical Measurement Systems for Industrial Inspection XI
Peter Lehmann; Wolfgang Osten; Armando Albertazzi Gonçalves Jr., Editor(s)

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