Abstract

Single input state polarization sensitive optical coherence tomography (PS-OCT) generally uses circularly polarized light incident on the sample to derive cumulative sample retardation. Two input states are required for fiber-based PS-OCT where the polarization state incident on the tissue is uncontrolled to avoid the possible alignment of the polarization state with the sample optic axis, and to reconstruct local retardation, i.e. depth-resolved tissue birefringence. Here we demonstrate a new processing paradigm and achieve local retardation imaging in the coronary artery of patients using only a single input polarization state. This is accomplished by recognizing that the evolution of the polarization state in systems that measure the round-trip signal in purely retarding samples is constrained to progress through a specific polarization state that can be identified directly from the measured data. In addition, we use spectral binning and exploit the polarization mode dispersion present in the imaging system to recover the sample birefringence even when the sample optic axis aligns with the polarization state in individual spectral bins. We validate our reconstruction method using clinical intravascular PS-OCT data acquired with two alternating input polarization states. Using only one or the other of the two input states, we reconstruct birefringence maps that match closely the birefringence signal reconstructed using both input polarization states simultaneously. While the birefringence reconstructed from a single input state remains noisier than the two-input-state signal, this novel reconstruction offers a compelling reduction in the system complexity needed to perform depth-resolved birefringence imaging.

© 2019 SPIE/OSA