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Proceedings Paper

Precision optical metrology without lasers
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Paper Abstract

Optical metrology is a key technique when it comes to precise and fast measurement with a resolution down to the micrometer or even nanometer regime. The choice of a particular optical metrology technique and the quality of results depends on sample parameters such as size, geometry and surface roughness as well as user requirements such as resolution, measurement time and robustness. Interferometry-based techniques are well known for their low measurement uncertainty in the nm range, but usually require careful isolation against vibration and a laser source that often needs shielding for reasons of eye-safety. In this paper, we concentrate on high precision optical metrology without lasers by using the gradient based measurement technique of deflectometry and the finite difference based technique of shear interferometry. Careful calibration of deflectometry systems allows one to investigate virtually all kinds of reflecting surfaces including aspheres or free-form surfaces with measurement uncertainties below the μm level. Computational Shear Interferometry (CoSI) allows us to combine interferometric accuracy and the possibility to use cheap and eye-safe low-brilliance light sources such as e.g. fiber coupled LEDs or even liquid crystal displays. We use CoSI e.g. for quantitative phase contrast imaging in microscopy. We highlight the advantages of both methods, discuss their transfer functions and present results on the precision of both techniques.

Paper Details

Date Published: 17 July 2015
PDF: 8 pages
Proc. SPIE 9524, International Conference on Optical and Photonic Engineering (icOPEN 2015), 952403 (17 July 2015); doi: 10.1117/12.2183451
Show Author Affiliations
Ralf B. Bergmann, Bremer Institut für angewandte Strahltechnik GmbH (Germany)
Univ. of Bremen (Germany)
Jan Burke, Bremer Institut für angewandte Strahltechnik GmbH (Germany)
Claas Falldorf, Bremer Institut für angewandte Strahltechnik GmbH (Germany)

Published in SPIE Proceedings Vol. 9524:
International Conference on Optical and Photonic Engineering (icOPEN 2015)
Anand K. Asundi; Yu Fu, Editor(s)

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