Schematic diagram of endoscopic PSOCT system. SS = swept-source laser, PC = polarization controller, CIRC = circulator, C = collimator, POL = polarizer, RM = reference mirror, AIM = aiming laser, WDM = wavelength division multiplexer, FORJ = fiber optic rotary joint, RPC = rotary pullback catheter, PMFC = polarization maintaining fiber coupler, PBS = polarization beamsplitter, BD = balanced detector. Dashed (red) lines indicate PM fiber; all others are SM fiber. The SM and PM patch cables indicated within the dotted box can be removed to yield a standard (polarization-independent) OCT imaging system.