Differential phase-contrast optical coherence tomography allows one to measure the path-length differences of two transversally separated beams in the nanometer range. We calculate these path-length differences from the phase functions of the interferometric signals. Pure phase objects consisting of chromium layers containing steps of approximately 100–200-nm height were imaged. Phase differences can be measured with a precision of ±2°, corresponding to a path-difference resolution of 2–3 nm. To investigate the influence of scattering, we imaged the phase objects through scattering layers with increasing scattering coefficients. The limit of phase imaging through these layers was at approximately 8–9 mean free path lengths thick (single pass).
© 2001 Optical Society of America
(110.4500) Imaging systems : Optical coherence tomography
(120.3180) Instrumentation, measurement, and metrology : Interferometry
(120.5050) Instrumentation, measurement, and metrology : Phase measurement
(170.4500) Medical optics and biotechnology : Optical coherence tomography
Markus Sticker, Christoph K. Hitzenberger, Rainer Leitgeb, and Adolf F. Fercher, "Quantitative differential phase measurement and imaging in transparent and turbid media by optical coherence tomography," Opt. Lett. 26, 518-520 (2001)