Modified Monte Carlo of photon transport for studying the imaging properties in highly scattering media

We propose a new method of photon transport to analyze the imaging properties of focused light in highly scattering media. The Monte Carlo based photon transport model is modified to a semi-complete quantum mechanical realization that incorporates probability amplitudes on the path of the unscattered photons. This approach incorporates a phase term on the propagating photons that allows a diffraction-limited analysis on the three-dimensional (3D) photon distribution. The interaction between the photons and the lens are treated in the macroscopic level where the lens is considered as a phase transformer that delays the photons by the amount proportional to the thickness of the lens at each embarkation point. When a photon deviates from its original path due to scattering, the probability amplitude of the photon is no longer considered and the intensity of scattered light is calculated similar to the method proposed by Flock[l]. The total intensity is derived by the sum of the unscattered light and the scattered intensity. The 3D point spread functions of objective lenses that are commonly used for microscopic imaging of thick biological samples are presented. Degradation of the 3D PSF is analyzed when the focal plane is at some distance below the surface of the medium with known optical properties.