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Digital holography on moving objects: multiwavelength height measurements on inclined surfaces
Author(s): Annelie Schiller; Tobias Beckmann; Markus Fratz; Dominik Belzer; Alexander Bertz; Daniel Carl; Karsten Buse
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Paper Abstract

Multiwavelength digital holography on moving objects enables fast and precise inline-measurements of surface pro files. Due to the use of multiple wavelengths, optically rough surfaces with structure heights in the micrometer range can be mapped unambiguously. In this work we explore the influence of the object velocity on height measurements on inclined surfaces. We show measurements using spatial-phase-shifting holography employing two wavelengths and object velocities of up to 90 mm/s with eye-safe cw-lasers with less than 1 mW of laser light. Despite motion blur exceeding the mean speckle size, reliable height measurements can be conducted at these velocities. The height map of a metal cone with two different slope angles (1° , 10° ) is measured at an exposure time of 2 ms. Using line shaped illumination, each frame yields a height map of approximately 2 x 17 mm2. The overlap between the frames allows averaging as the image is put together, improving data quality. The mean repeatability of the height information in the investigated setup is better than 4.5 µm at a synthetic wavelength of 214 µm.

Paper Details

Date Published: 26 June 2017
PDF: 7 pages
Proc. SPIE 10329, Optical Measurement Systems for Industrial Inspection X, 103290D (26 June 2017); doi: 10.1117/12.2270176
Show Author Affiliations
Annelie Schiller, Fraunhofer-Institut für Physikalische Messtechnik (Germany)
Tobias Beckmann, Fraunhofer-Institut für Physikalische Messtechnik (Germany)
Markus Fratz, Fraunhofer-Institut für Physikalische Messtechnik (Germany)
Dominik Belzer, Fraunhofer-Institut für Physikalische Messtechnik (Germany)
Alexander Bertz, Fraunhofer-Institut für Physikalische Messtechnik (Germany)
Daniel Carl, Fraunhofer-Institut für Physikalische Messtechnik (Germany)
Karsten Buse, Fraunhofer-Institut für Physikalische Messtechnik (Germany)
Univ. of Freiburg (Germany)


Published in SPIE Proceedings Vol. 10329:
Optical Measurement Systems for Industrial Inspection X
Peter Lehmann; Wolfgang Osten; Armando Albertazzi Gonçalves, Editor(s)

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