Theoretical, experimental, and computational aspects of optical property determination of turbid media by using frequency-domain laser infrared photothermal radiometry

In this work, the optical and thermal properties of tissuelike materials ar e measured by using frequency-domain infrared photothermal radiometry, This technique is better suited for quantitative multiparameter optical measure ments than the widely used pulsed-laser photothermal radiometry (PPTR) beca use of the availability of two independent signal channels, amplitude and p hase, and the superior signal-to-noise ratio provided by synchronous lock-i n detection. A rigorous three-dimensional (3-D) thermal-wave formulation wi th a 3-D diffuse and coherent photon-density-wave source is applied to data from model phantoms. The combined theoretical, experimental, and computati onal methodology shows good promise with regard to its analytical ability t o measure optical properties of turbid media uniquely, as compared with PPT R, which exhibits uniqueness problems. From data sets obtained, by using ca librated test phantoms, the reduced optical scattering and absorption coeff icients were found to be within 20% and 10%, respectively, of the values in dependently derived by using Mie theory, and spectrophotometric measurement s. (C) 2001 Optical Society of America.