Spectroscopic optical coherence tomography

Summary form only given. Implementations of OCT, which take advantage of the spectral bandwidth of low coherence sources for tissue spectroscopy, have not yet been reported. We describe a novel technique for depth-resolved coherent backscatter spectroscopy, which is an extension of OCT technology. Our system incorporates an OCT scanner illuminated by a superluminescent diode (SLD) at 1.3-/spl mu/m center wavelength. In the low-coherence interferometer, a scanning reference mirror generates the temporal cross-correlation function of light reflected from the reference mirror, and that backscattered from the sample arm target. A separate helium-neon interferometer is utilized for digital correction of artifacts in the low-coherence interferometer output due to nonlinearities in the reference arm retroreflector stage velocity. The low-coherence interferometric signal is digitally demodulated and filtered to obtain the complete complex envelope of the interferometric signal, which is required for the spectroscopic technique. Using this system, low-coherence interferograms with accurate sampling intervals and high dynamic range (>98 dB) are acquired.