Evaluation of scaling Monte Carlo methods for backscattering properties of turbid media with Gaussian incidence

The scaling Monte Carlo method and Gaussian model are applied to simulate the transportation of light beam with arbitrary waist radius. Much of the time, Monte Carlo simulation is performed for pencil or cone beam where the initial status of the photon is identical. In practical application, incident light is always focused on the sample to form approximate Gauss distribution on the surface. With alteration of focus position in the sample, the initial status of the photon will not be identical any more. Using the hyperboloid method, the initial reflect angle and coordinates are generated statistically according to the size of Gaussian waist and focus depth. Scaling calculation is performed with baseline data from standard Monte Carlo simulation. The scaling method incorporated with the Gaussian model was tested, and proved effective over a range of scattering coefficients from 20% to 180% relative to the value used in baseline simulation. In most cases, percentage error was less than 10%. The increasing of focus depth will result in larger error of scaled radial reflectance in the region close to the optical axis. In addition to evaluating accuracy of scaling the Monte Carlo method, this study has given implications for inverse Monte Carlo with arbitrary parameters of optical system.