23 May 2001 Overcoming the 2π ambiguity in low-coherence interferometric differential phase measurements
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Proceedings Volume 4251, Coherence Domain Optical Methods in Biomedical Science and Clinical Applications V; (2001) https://doi.org/10.1117/12.427875
Event: BiOS 2001 The International Symposium on Biomedical Optics, 2001, San Jose, CA, United States
Abstract
Quantitative phase measurements by optical coherence tomography and low coherence interferometry are restricted by the well known 2(pi) ambiguity to path length differences smaller than +/- (lambda) /2. We present a method that can overcome this ambiguity. We introduce a slight imbalance of dispersive material between the reference and sample arms of the interferometer. Thereby, short and long wavelengths of the source spectrum are separated within the signature of the interferometric signal. This causes a varying phase slope within the signal. To measure phase differences between two adjacent beams traversing a sample, the total interferometric signal of the two beams is recorded. The phase difference is calculated by subtracting the phase values obtained for both recorded signals. Without dispersive effects, the phase difference is constant across the coherence envelope. With the dispersive effect, the phase difference varies (because of the varying phase slopes) as a function of position within the interferometric signal. The slope of the phase difference between the two signals is proportional to the optical path difference, without 2(pi) ambiguity.
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Christoph K. Hitzenberger, Christoph K. Hitzenberger, Markus Sticker, Markus Sticker, Rainer Leitgeb, Rainer Leitgeb, Harald Sattmann, Harald Sattmann, Adolf Friedrich Fercher, Adolf Friedrich Fercher, "Overcoming the 2π ambiguity in low-coherence interferometric differential phase measurements", Proc. SPIE 4251, Coherence Domain Optical Methods in Biomedical Science and Clinical Applications V, (23 May 2001); doi: 10.1117/12.427875; https://doi.org/10.1117/12.427875
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