PSOCT

PSOCT, or polarization-sensitive optical coherence tomography, is an imaging modality that extends conventional OCT by measuring polarization properties of tissue in addition to intensity. By combining interferometric depth resolution with polarization sensitivity, PSOCT can provide maps of tissue birefringence, optic axis orientation, and other polarization metrics, enabling contrast based on microstructural organization.

A PSOCT system typically uses a polarized light source, a polarization-maintaining interferometer, and polarization-resolved detection. The detected interferometric signals are analyzed in the Stokes or Jones formalism to recover depth-resolved retardance, fast-axis orientation, and sometimes diattenuation and degree of polarization. Common implementations employ spectral-domain or swept-source OCT with polarization-diverse detection. System calibration and compensation for polarization changes introduced by the optics are essential for accurate measurements.

Applications of PSOCT are broad. In ophthalmology, it is used to characterize retinal nerve fiber layer birefringence and collagen-based structures in the sclera and cornea, aiding glaucoma assessment and studies of retinal biomechanics. In dermatology, cardiology, and neuroscience, PSOCT provides insights into tissue organization, fibrosis, myelination, and other anisotropic properties. It is also used in research to visualize collagen and muscle fibers in various tissues and in dental imaging.

Advantages include providing complementary information to standard OCT, with sensitivity to microstructural organization beyond scattering intensity. Limitations involve sensitivity to motion and depolarization, increased data and processing complexity, and the need for careful calibration and higher system complexity, which can affect acquisition time and cost.