Simulation Study On Polarized Light Transport In Different Media With Monte Carlo Method And Optical Coherence Tomography

Optical coherence tomography is a non-destructive and high-resolution optical measuring technology developed in recent years. The processes and phenomena of light transportation in media and their applications may play an important role for the development of optical coherence tomography technologies. The simulation study could improve the understanding of light transportation in media and provide theory bases for light detection technology. In this paper polarized light transportations in different media are simulated and investigated with a Monte Carlo method and some research on optical coherence tomography are carried out.In the area of Monte Carlo simulation of polarized light transportation in turbid media, a physical model of tracking polarized states and photon positions is established when polarized lights travel in isotropic and birefringence media, respectively, using Stokes-Mueller formula and considering media's optical properties, such as refractive index, transmission rate, absorption coefficient, reflection coefficient and anisotropy factor etc. When polarized photons travel in these media, their polarized states, scattering angles and azimuth coordinates are obtained in the model. In order to simulate polarized light transportation in isotropic and birefringence media, C language programs base on the model with a Monte Carlo method are designed and compiled. When incidences of lights are in different polarization states, light transportations in isotropic and birefringence media, respectively, are simulated. Intensities of Stokes vector's elements of the backscattering lights from these media are achieved. These Stokes vector's elements intensity data are processed with Matlab programs. The characteristics of Mueller matrix elements for isotropic and birefringence media are analyzed. At the same time, the degrees of polarization for the backscattering lights are investigated while incidences of light are different polarized lights.In the area of the studies on optical coherence tomography (OCT), on the one hand, using the traditional OCT technology, a method of measuring a sample's refractive index using the images obtained by a OCT system is presented. By analyzing the principle of the optical path matching, the theory of measuring the refractive index of a sample using OCT images and its process are given. Experiments with glass slides and cucumber tissue as samples are carried. And the measurement results are analyzed. In addition, for the purpose of simulation the wide-field OCT (WFOCT) system, the detection signal of traditional OCT system is simulated with Monte Carlo method, and the corresponding program of simulation is compiled. Using this program, the detection signal of traditional OCT of certain conditions is simulated, and the simulation results are provided. On the other hand, using WFOCT technology, whose light source radiates wide field white light, the samples'surface is reconstructed with monochrome and color lights. The samples'stratums structures are reconstructed through vertical scanning with red wide-field light. According to related experimental results, the factors that influence the transverse and vertical resolution of WFOCT system are discussed.