We present a compact, fast, and versatile fiber-optic probe system for real-time determination of tissue optical properties from spatially resolved continuous-wave diffuse reflectance measurements. The system collects one set of reflectance data from six source–detector distances at four arbitrary wavelengths with a maximum overall sampling rate of 100 Hz. Multivariate calibration techniques based on two-dimensional polynomial fitting are employed to extract and display the absorption and reduced scattering coefficients in real-time mode. The four wavelengths of the current configuration are 660, 785, 805, and 974 nm, respectively. Cross-validation tests on a 6 × 7 calibration matrix of Intralipid–dye phantoms showed that the mean prediction error at, e.g., 785 nm was 2.8% for the absorption coefficient and 1.3% for 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 for the absorption coefficient and 6–16/cm for the reduced scattering coefficient. Finally, we also present and discuss results from preliminary skin tissue measurements.
© 2001 Optical Society of America
(170.1470) Medical optics and biotechnology : Blood or tissue constituent monitoring
(170.1580) Medical optics and biotechnology : Chemometrics
(170.3890) Medical optics and biotechnology : Medical optics instrumentation
(170.6510) Medical optics and biotechnology : Spectroscopy, tissue diagnostics
Jan S. Dam, Carsten B. Pedersen, Torben Dalgaard, Paul Erik Fabricius, Prakasa Aruna, and Stefan Andersson-Engels, "Fiber-optic probe for noninvasive real-time determination of tissue optical properties at multiple wavelengths," Appl. Opt. 40, 1155-1164 (2001)