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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 24 — Dec. 2, 2013
  • pp: 29955–29967

Refractive index measurements of multiple layers using numerical refocusing in FF-OCT

Gihyeon Min, Woo June Choi, Ju Wan Kim, and Byeong Ha Lee  »View Author Affiliations

Optics Express, Vol. 21, Issue 24, pp. 29955-29967 (2013)

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We propose and demonstrate the novel method of refractive index (RI) measurement for each layer of multilayered samples, which is based on numerical refocusing in full field optical coherence tomography (FF-OCT). The en-face FF-OCT image on an inner layer boundary of a multilayered sample is unintentionally blurred or defocused due to the RI of the sample itself, but can be numerically refocused. The refocusing is performed by numerically shifting the image sensor plane of the system, in general. However, by calculating the corresponding sample shift and then compared it with the actual sample shifting distance, we could extract the average RI of the layer between any two layer boundaries within the multilayered sample. In addition, the thickness of that particular layer could be derived at the same time. For the idea proof, several samples were prepared by stacking, for each sample, two transparent plates with a gap in between. While changing the material of the plate and filling the gap with oil, the RIs of the plate and the oil were measured. For oils of various RIs, from 1.2977 to 1.3857, the measured RIs were well matched with the reported ones within 0.205%. Moreover, even with a stack of various and multiple plates in front of the same oil layer, the oil RI and the physical thickness of the oil layer were extracted with average errors of only 0.065% and 0.990%, respectively.

© 2013 Optical Society of America

OCIS Codes
(110.4500) Imaging systems : Optical coherence tomography
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(290.3030) Scattering : Index measurements
(090.1995) Holography : Digital holography

ToC Category:
Instrumentation, Measurement, and Metrology

Original Manuscript: September 4, 2013
Revised Manuscript: November 2, 2013
Manuscript Accepted: November 12, 2013
Published: November 27, 2013

Virtual Issues
Vol. 9, Iss. 2 Virtual Journal for Biomedical Optics

Gihyeon Min, Woo June Choi, Ju Wan Kim, and Byeong Ha Lee, "Refractive index measurements of multiple layers using numerical refocusing in FF-OCT," Opt. Express 21, 29955-29967 (2013)

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