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Proceedings Paper

Discrete step wavemeter
Author(s): Carl Aleksoff; Hao Yu
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Paper Abstract

Tunable lasers are used in optical metrology, but their intrinsic tuning accuracy is sometimes inadequate and an external wavemeter is then required to measure the wavelength more accurately. In this paper, we present the design of a discrete step wavemeter to measure the wavelength of the light from a tunable laser during the operation of a multi-wavelength interferometric shape measuring system. This relatively low-cost wavemeter is embedded in the metrology system and consists of a discrete set of small retroreflectors mounted at different ranges on a super-invar base, which eases alignment and allows it to be insensitive to temperature changes. During operation, interference patterns from the retroreflectors are captured by a camera for each phase shift and commanded wavelength and analyzed to determine the actual wavelength. The phase measurement uses a least square fitting algorithm. A Fourier Transform peak finding measurement technique is used for phase unwrapping. Both numerical simulation and experiments indicate improved system performance using this internal wavemeter technique.

Paper Details

Date Published: 2 August 2010
PDF: 10 pages
Proc. SPIE 7790, Interferometry XV: Techniques and Analysis, 77900H (2 August 2010); doi: 10.1117/12.860897
Show Author Affiliations
Carl Aleksoff, Coherix Corp. (United States)
Hao Yu, Univ. of Michigan (United States)

Published in SPIE Proceedings Vol. 7790:
Interferometry XV: Techniques and Analysis
Catherine E. Towers; Joanna Schmit; Katherine Creath, Editor(s)

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