Broadband UV-Vis optical property measurement in layered turbid media

Quantitative data on the fundamental optical properties (OPs) of biological tissue, including absorption and reduced scattering coefficients are important for elucidating light propagation during optical spectroscopy and facilitating diagnostic device design and optimization, and may enable rapid detection of early neoplasia. However, systems for in situ broadband measurement of mucosal tissue OPs in the ultraviolet-visible range have not been realized. In this study, we evaluated a fiberoptic-based reflectance system, coupled with neural network inverse models (trained with Monte Carlo simulation data), for measuring OPs in highly attenuating, two-layer turbid media. The experimental system incorporated a broadband light source, a fiberoptic probe and a CCD camera. The calibration method involved a set of standard nigrosin-microsphere phantoms as well as a more permanent spectralon phantom for quality assurance testing and recalibration. The system was experimentally evaluated using two-layer hydrogel phantoms with hemoglobin and polystyrene microspheres. The effects of tissue top-layer thickness and fitting approaches based on known absorption and scattering distributions were discussed. With our method, measurements with error less than 28% were obtained in the wavelength range of 350-630 nm.