Fiber-optic probe for noninvasive real-time determination of tissue optical properties at multiple wavelengths

We present a compact, fast, and versatile fiber-optic probe system for real -time determination of tissue optical properties from spatially resolved co ntinuous-wave diffuse reflectance measurements. The system collects one set of reflectance data from six source-detector distances at four arbitrary w avelengths with a maximum overall sampling rate of 100 Hz. Multivariate cal ibration techniques based on two-dimensional polynomial fitting are employe d to extract and display the absorption and reduced scattering coefficients in real-time mode. The four wavelengths of the current configuration are 6 60, 785, 805, and 974 nm, respectively. Cross-validation tests on a 6 x 7 c alibration matrix of Intralipid-dye phantoms showed that the mean predictio n error at, e.g., 785 nm was 2.8% for the absorption coefficient and 1.3% f or the reduced scattering coefficient. The errors are relative to the range of the optical properties of the phantoms at 785 nm, which were 0-0.3/cm f or the absorption coefficient and 6-16/cm for the reduced scattering coeffi cient. Finally, we also present and discuss results from preliminary skin t issue measurements. (C) 2001 Optical Society of America OCIS codes: 170.147 0, 170.1580, 170.3890, 170.6510.