Evaluation of optical coherence quantitation of analytes in turbid media by use of two wavelengths

We introduce a novel method for determining analyte concentration as a func tion of depth in a highly scattering media by use of a dual-wavelength opti cal coherence tomography system. We account for the effect of scattering on the measured attenuation by using a second wavelength that is not absorbed by the sample. We assess the applicability of this technique by measuring the concentration of water in an Intralipid phantom, using a probe waveleng th of 1.53 mu m and a reference wavelength of 1.31 mu m. The results of our study show a strong correlation between the measured absorption and the wa ter content of the sample. The accuracy of the technique, however, was limi ted by the dominance of scattering over absorption in the turbid media. Thu s, although the effects of scattering were minimized, significant errors re mained in the calculated absorption values. More-accurate results could be obtained with the use of more powerful superluminescent diodes and a choice of wavelengths at which absorption effects are more significant relative t o scattering. (C) 1999 Optical Society of America.