High speed spectral domain functional optical coherence tomography and optical doppler tomography for in vivo blood flow dynamics and tissue structure

An apparatus for tomographic imaging of a sample comprising:

• an interferometer;
• a swept frequency source of at least partially coherent radiation coupled to the interferometer;
• a phase modulator of the radiation in the interferometer operating at a stable modulation frequency combined with a carrier signal at a carrier frequency sufficient to separate the negative and positive frequency terms of an interference fringe signal from each other and from the low frequency noise which is not affected by the carrier frequency, the phase modulator being in optical circuit in the interferometer;
• a detector of interference fringes of the radiation backscattered from the sample into the interferometer, where the detector obtains a spectral signal and is coupled to the interferometer;
• circuit means coupled to the detector for transforming the spectral signal of the detected backscattered interference fringes to obtain a location dependent signal, including the Doppler shift and variance, at each pixel location in a window;
• and
• a generator to produce a displayable tomographic image of the fluid flow in the data window and of the structure of the scanned sample in the data window from the location dependent signal coupled from the circuit means.