PROCEEDINGS ARTICLE | November 16, 2004
Proc. SPIE. 5579, Photonics North 2004: Photonic Applications in Telecommunications, Sensors, Software, and Lasers
KEYWORDS: Mirrors, Polarization, Birefringence, Tissues, Optical coherence tomography, Reflectivity, Single mode fibers, In vivo imaging, Tissue optics, Signal detection
Polarization sensitive optical coherence tomography (PS-OCT) takes into account the vector nature of light waves (state of polarization). The most complete information about the polarization properties of a biological target is given by the depth resolved Mueller matrix elements, however, it is difficult to construct such a system for in-vivo examination. We designed and assembled a simpler system, with two incoherent channels to provide limited information, but essential on the polarization properties of the tissue. The interferometer is a hybrid configuration of bulk optic and single mode optical fiber components. No polarization maintaining fiber is used. The reference and sample beams interfere in single mode optical couplers. The low coherence light source is a superluminescent diode of 850 nm center wavelength and 25 nm spectrum FWHM (which corresponds to a depth resolution of 12 microns in tissue). The system can display either a pair of two polarisation sensitive OCT images, corresponding to linear orthogonal polarisation directions or a pair of images, a polarisation insensitive (pure reflectivity) image and a birefringence retardation map. The 12 bit grayscale images are collected by fast en-face scanning (T-scan) at 2 frames/s. We demonstrate in vivo en face images of the retinal nerve fiber layer, lamina cribrosa, cornea and teeth. A rotation angle of 0.3 degrees per micron was evaluated from the retinal nerve fiber layer and lamina cribrosa.
