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Proceedings Paper

Calibration of z-axis linearity for arbitrary optical topography measuring instruments
Author(s): Matthias Eifler; Jörg Seewig; Julian Hering; Georg von Freymann
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Paper Abstract

The calibration of the height axis of optical topography measurement instruments is essential for reliable topography measurements. A state of the art technology for the calibration of the linearity and amplification of the z-axis is the use of step height artefacts. However, a proper calibration requires numerous step heights at different positions within the measurement range. The procedure is extensive and uses artificial surface structures that are not related to real measurement tasks.

Concerning these limitations, approaches should to be developed that work for arbitrary topography measurement devices and require little effort. Hence, we propose calibration artefacts which are based on the 3D-Abbott-Curve and image desired surface characteristics. Further, real geometric structures are used as an initial point of the calibration artefact.

Based on these considerations, an algorithm is introduced which transforms an arbitrary measured surface into a measurement artefact for the z-axis linearity. The method works both for profiles and topographies. For considering effects of manufacturing, measuring, and evaluation an iterative approach is chosen. The mathematical impact of these processes can be calculated with morphological signal processing.

The artefact is manufactured with 3D laser lithography and characterized with different optical measurement devices. An introduced calibration routine can calibrate the entire z-axis-range within one measurement and minimizes the required effort. With the results it is possible to locate potential linearity deviations and to adjust the z-axis. Results of different optical measurement principles are compared in order to evaluate the capabilities of the new artefact.

Paper Details

Date Published: 22 June 2015
PDF: 10 pages
Proc. SPIE 9525, Optical Measurement Systems for Industrial Inspection IX, 952510 (22 June 2015); doi: 10.1117/12.2190737
Show Author Affiliations
Matthias Eifler, Univ. Kaiserslautern (Germany)
Jörg Seewig, Univ. Kaiserslautern (Germany)
Julian Hering, Univ. Kaiserslautern (Germany)
Georg von Freymann, Univ. Kaiserslautern (Germany)
Fraunhofer-Institut für Physikalische Messtechnik (Germany)

Published in SPIE Proceedings Vol. 9525:
Optical Measurement Systems for Industrial Inspection IX
Peter Lehmann; Wolfgang Osten; Armando Albertazzi Gonçalves Jr., Editor(s)

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