Determining the Scale Factor of a Video-Reflectometry Set-Up

摘要

Several inversion techniques exist for determining the optical properties of biological tissues and other turbid media. Video reflectometry is one of them, which is an easy to implement experimental set-up. It is known that the radial reflectance profiles obtained with this experimental set-up and those obtained theoretically, do not overlap. Therefore, it is essential to find a scale factor K, which minimizes the distance between the two curves as a prelude to a nonlinear fitting that leads to the determination of optical properties of unknown samples. In order to find this factor we proposed to use a teflon disk with known optical properties. This paper presents the algorithm and the experimental results of the determination of the scale factor K for our installation of video reflectometry. The scale factor was determined by a least squares linear fitting procedure of the experimental reflectance curve and the theoretical one for a teflon disk. The radial distance r_0 for an optimal fitting procedure was found considering the requirement that the difference between the curves of light-tissue interaction in the diffusion approximation and the synthetic data generated with the code MCML should be zero. Finally, we investigated the influence of geometric parameters of our experimental set-up on the value of the constant K.