Three-dimensional polarization-sensitive imaging of human retina in vivo with phase-resolved transversal OCT

Polarization sensitive optical coherence tomography (PS-OCT) extends the concept of OCT to obtain additional information on the polarizing properties of tissue. Recently, we reported on a PS-OCT system based on transversal scanning of the probing beam across the sample, and operating at a center wavelength of 1310 nm. We now modified the instrument to allow imaging of the human retina in vivo. The instrument uses an SLD light source centered at 824 nm (FWHM bandwidth: 33 nm). A stable carrier frequency is generated by acousto optic modulators. A two-channel polarization sensitive detection unit is used to obtain amplitude and phase of the interference signals in two orthogonal polarization channels. This allows to measure and image three parameters simultaneously: reflectivity, retardation, and birefringent axis orientation. The instrument can be operated in different ways: 2D imaging along x-z or y-z planes (B-scans), along the x-y plane (C-scan), and 3D imaging are possible. Compared to our previous instrument, the imaging speed was increased by an order of magnitude. This allowed to record in vivo PS-OCT images in the fovea and nerve head region of healthy volunteers.