Monte Carlo Simulation for Optical Coherence Tomography System
光学相干层析成像系统的蒙特卡罗模拟

The optical fiber & focusing system in the sampling arm of OCT system and the measured sample were taken as a whole to simulate the formation mechanism of OCT signal.Whether a photon within sampling beam would contribute to OCT signal and how much contribution it would do were determined by tracing its stochastic propagating trajectory through the focusing system and within the sample.OCT signal was composed of the contributions of all photons in sampling beam.The simulated results and the experimental results on IntralipidTMshow: 1) High scattering coefficient and weakly forward scattering are the prime causes of OCT signal attenuation as measurement depth increase.2) For a given focusing system,there exits a best numerical range for the numerical aperture (NA) of the fiber.OCT signal is very weak when NA is small,and OCT signal profile only changes a bit when NA exceeds the best numerical range and increases continuously.3) When the optical axis of the fiber is offset a distance h from the axis of focusing system,OCT signal decreases with the increase of h.