Method and apparatus for differential phase optical coherence tomography

One form of the present invention is a dual channel optical reflectometer composed of a birefringent path coupler and an optical source path that is optically connected to the path coupler. After entering the path coupler, light is split into birefringent reference and sample paths. The reference path is optically aligned with a first collimating lens, and the collimating lens is directed into a scanning delay line. There is also a birefringent optical sample path that is also optically connected to the path coupler. The sample path is optically aligned with a polarization channel separator/combiner and a lens, to focus and direct optical beams into the turbid sample. Light backscattered from the turbid sample is collected by the second lens and orthogonal polarization channels are reunited by the polarization channel combiner. An analog-to-digital converter is connected to the amplifier, and a computer is connected to the analog-to-digital converter to analyze the output.