Spectroscopic low coherence interferometry using a supercontinuum source and an ultra broadband spectrometer

Spectroscopic optical coherence tomography (SOCT) combines the imaging capability of optical coherence tomography with spectroscopic absorption information. SOCT requires a large bandwidth combined with a broadband spectrometer, due to the processing of the measured data, which includes dividing the spectrum in spectral bands. Both, spectral and axial resolution of SOCT depend on the spectral width of each window. A supercontinuum source with its broad spectrum allows a sufficient number of windows combined with a reasonable axial resolution, which depends on the application. Here a SOCT system is used in the visible spectral range from 480 to 730 nm by combining a supercontinuum light source, a Michelson interferometer and a commercial available broadband spectrometer. This wavelength range is chosen because it covers a range of useful absorbers, including that of human proteins. The system is tested with a laser dye rhodamine B for calibration and verification. Rhodamine B has an absorption peak at around 542 nm, which resembles the absorption spectrum of several proteins in the globin group. The results show that the absorption spectrum of rhodamine B can be reconstructed with sufficient accuracy and demonstrate that varying spectroscopic information can be retrieved from different depths.