Measuring of optical properties of small volume samples using time-resolved reflectance spectroscopy

Measurements of optical properties of biological tissues are necessary to develop optical diagnostic instruments. Although various methods to measure the optical properties of biological tissue have been proposed, very few measurements have been carried out in vivo because of their difficulties.We are developing a new method to obtain the optical properties in vivo using time -resolved measurement system. This new method determines the optical properties by comparing the experimental results of time- resolved measurement with the results of a series of Monte Carlo simulation using known optical properties. By combining results of a Monte Carlo simulation with the time-resolved reflectance measurement for the case of small source-detector distance, it is possible to measure the optical properties of small samples in vivo to which the diffusion approximation can't be applied. However, the optical properties obtained from the time-resolved reflectance method at small source-detector distances do not agree with the results from the integrating sphere system. The time- resolved reflectance at small source- detector distance should be influenced by the scattering phase function of the tissue. We discuss the effects of the phase function on the measurement of the optical properties obtained from time-resolved reflectance method.