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2pi ambiguity-free optical distance measurement with subnanometer precision with a novel phase-crossing low-coherence interferometer

Yang, Changhuei and Wax, Adam and Dasari, Ramachandra R. and Feld, Michael S. (2002) 2pi ambiguity-free optical distance measurement with subnanometer precision with a novel phase-crossing low-coherence interferometer. Optics Letters, 27 (2). pp. 77-79. ISSN 0146-9592. http://resolver.caltech.edu/CaltechAUTHORS:YANol02b

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Abstract

We report a highly accurate phase-based technique for measuring arbitrarily long optical distance with subnanometer precision. The method employs a Michelson interferometer with a pair of harmonically related light sources, one cw and the other low coherence. By slightly detuning (~2 nm) the center wavelength of the low-coherence source between scans of the target sample, we can use the phase relationship between the heterodyne signals of the cw and the low-coherence light to measure the separation between reflecting interfaces with subnanometer precision. As this technique is completely free of 2pi ambiguity, an issue that plagues most phase-based techniques, it can be used to measure arbitrarily long optical distances without loss of precision. We demonstrate one application of this technique, the high-precision determination of the differential refractive index.


Item Type:Article
Additional Information:© 2002 Optical Society of America Received August 8, 2001 This work was carried out at the Massachusetts Institute of Technology Laser Biomedical Research Center and supported by grants from the National Institutes of Health [(NIH) P41-RR02594] and Hamamatsu Corporation. Adam Wax is supported by a National Research Service Award from the NIH.
Subject Keywords:Fringe analysis; Interferometry; Metrological instrumentation; Phase measurement
Record Number:CaltechAUTHORS:YANol02b
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:YANol02b
Alternative URL:http://www.opticsinfobase.org/abstract.cfm?URI=ol-27-2-77
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3326
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:30 May 2006
Last Modified:08 Dec 2014 23:19

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