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High-precision lateral distortion measurement and correction in coherence scanning interferometry using an arbitrary surface

Ekberg, Peter; Su, Rong; Leach, Richard K.

Authors

Peter Ekberg

Rong Su

Richard K. Leach



Abstract

Lateral optical distortion is present in most optical imaging systems. In coherence scanning interferometry, distortion may cause field-dependent systematic errors in the measurement of surface topography. These errors become critical when high-precision surfaces, e.g. precision optics, are measured. Current calibration and correction methods for distortion require some form of calibration artefact that has a smooth local surface and a grid of high-precision manufactured features. Moreover, to ensure high accuracy and precision of the absolute and relative locations of the features of these artefacts, requires their positions to be determined using a traceable measuring instrument, e.g. a metrological atomic force microscope. Thus, the manufacturing and calibration processes for calibration artefacts are often expensive and complex. In this paper, we demonstrate for the first time the calibration and correction of optical distortion in a coherence scanning interferometer system by using an arbitrary surface that contains some deviations from flat and has some features (possibly just contamination), such that feature detection is possible. By using image processing and a self-calibration technique, a precision of a few nanometres is achieved for the distortion correction. An inexpensive metal surface, e.g. the surface of a coin, or a scratched and defected mirror, which can be easily found in a laboratory or workshop, may be used. The cost of the distortion correction with nanometre level precision is reduced to almost zero if the absolute scale is not required. Although an absolute scale is still needed to make the calibration traceable, the problem of obtaining the traceability is simplified as only a traceable measure of the distance between two arbitrary points is needed. Thus, the total cost of transferring the traceability may also be reduced significantly using the proposed method.

Journal Article Type Article
Publication Date Jul 25, 2017
Journal Optics Express
Electronic ISSN 1094-4087
Publisher Optical Society of America
Peer Reviewed Peer Reviewed
Volume 25
Issue 16
APA6 Citation Ekberg, P., Su, R., & Leach, R. K. (2017). High-precision lateral distortion measurement and correction in coherence scanning interferometry using an arbitrary surface. Optics Express, 25(16), https://doi.org/10.1364/OE.25.018703
DOI https://doi.org/10.1364/OE.25.018703
Publisher URL https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-16-18703
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0





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