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Proceedings Paper

Development of a non-contact center thickness optical metrology system
Author(s): Michael J. Thorpe; Jason K. Brasseur; Peter A. Roos
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Paper Abstract

The last place an optics manufacturer wants to physically touch a lens is at the center. However, this is precisely what is currently done to measure center thickness of lenses. Using contact methods, the question is not whether the optic is damaged, it is whether the resulting damage is acceptably low. At Bridger Photonics, we have proven the feasibility of a non-contact center thickness metrology system to address this need. The apparatus uses a technique similar to swept-frequency optical coherence tomography to measure both physical thickness and optical thickness. From these measurements, the group index of refraction can also be determined. Moreover, the phase index can be determined, given the Sellmeier coefficients. In this presentation, we will report our demonstrated measurement range of 75 mm optical thickness (larger possible), as low as 20 nm precision, and group index of refraction determined to better than 5 parts is 105. We believe the metrology system resulting from these proof-of-principle demonstrations will be a valuable tool for precision optics manufacturing.

Paper Details

Date Published: 1 September 2015
PDF: 5 pages
Proc. SPIE 9576, Applied Advanced Optical Metrology Solutions, 95760I (1 September 2015); doi: 10.1117/12.2190163
Show Author Affiliations
Michael J. Thorpe, Bridger Photonics, Inc. (United States)
Jason K. Brasseur, Bridger Photonics, Inc. (United States)
Peter A. Roos, Bridger Photonics, Inc. (United States)

Published in SPIE Proceedings Vol. 9576:
Applied Advanced Optical Metrology Solutions
Erik Novak; James D. Trolinger, Editor(s)

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