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Phase and fringe order determination in wavelength scanning interferometry

Moschetti, Guiseppe; Forbes, Alistair; Leach, Richard K.; Jiang, Xiang; O'Connor, Daniel


Guiseppe Moschetti

Alistair Forbes

Xiang Jiang

Daniel O'Connor


A method to obtain unambiguous surface height measurements using wavelength scanning interferometry with an improved repeatability, comparable to that obtainable using phase shifting interferometry, is reported. Rather than determining the conventional fringe frequency-derived z height directly, the method uses the frequency to resolve the fringe order ambiguity, and combine this information with the more accurate and repeatable fringe phase derived z height. A theoretical model to evaluate the method’s performance in the presence of additive noise is derived and shown to be in good agreement with experiments. The measurement repeatability is improved by a factor of ten over that achieved when using frequency information alone, reaching the sub-nanometre range. Moreover, the z-axis non-linearity (bleed-through or ripple error) is reduced by a factor of ten. These order of magnitude improvements in measurement performance are demonstrated through a number of practical measurement examples.


Moschetti, G., Forbes, A., Leach, R. K., Jiang, X., & O'Connor, D. (2016). Phase and fringe order determination in wavelength scanning interferometry. Optics Express, 24(8), 8997-9012.

Journal Article Type Article
Acceptance Date Apr 16, 2016
Online Publication Date Apr 16, 2016
Publication Date Apr 16, 2016
Deposit Date Apr 18, 2016
Publicly Available Date Apr 18, 2016
Journal Optics Express
Electronic ISSN 1094-4087
Publisher Optical Society of America
Peer Reviewed Peer Reviewed
Volume 24
Issue 8
Pages 8997-9012
Public URL
Publisher URL
Additional Information © 2016 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.


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