Abstract
Polarization mode dispersion (PMD) has been recognized as a significant barrier to sensitive and reproducible birefringence measurements with fiber-based, polarization-sensitive optical coherence tomography systems. Here, we present a signal processing strategy that reconstructs the local retardation robustly in the presence of system PMD. The algorithm uses a spectral binning approach to limit the detrimental impact of system PMD and benefits from the final averaging of the PMD-corrected retardation vectors of the spectral bins. The algorithm was validated with numerical simulations and experimental measurements of a rubber phantom. When applied to the imaging of human cadaveric coronary arteries, the algorithm was found to yield a substantial improvement in the reconstructed birefringence maps.
Highlights
Polarization sensitive (PS) optical frequency domain imaging (OFDI) is an extension of conventional OFDI [1] or optical coherence tomography (OCT) that determines the change of the polarization state of the probe light, caused by propagation and reflection within the sample [2,3]
From the filtered Stokes vectors, the conventional algorithm retrieved the corresponding measure of degree of polarization uniformity (DOPU), followed by normalization and extraction of the local retardation
We presented a processing strategy to mitigate detrimental effects of system polarization mode dispersion (PMD) and reconstruct improved local retardation maps in a robust fashion, insensitive to fiber motion and probe rotation
Summary
Polarization sensitive (PS) optical frequency domain imaging (OFDI) is an extension of conventional OFDI [1] or optical coherence tomography (OCT) that determines the change of the polarization state of the probe light, caused by propagation and reflection within the sample [2,3] This capability is useful in biological tissue with regularly arranged fibrous architecture, such as collagen, that may induce form-birefringence and result in a measurable retardation signal. In order to benefit from the advantages of fiber-based setups, Saxer et al introduced a polarization modulation scheme [13], that was adapted in several variations [14,15] It deduces the effect of the sample on the probing light by observing the change of the polarization state of the detected light with sample depth independently for distinct consecutive (or otherwise multiplexed) input polarization states. A single calibration prior to the measurement to subtract a PMD-induced bias is impossible
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