The Acceleration And Electrical Field Representation Of Monte Carlo Simulation And Its Application In Optical Bio-imaging

Light, whose intensity is below the damage threshold, results minimal damage on the organism. Therefore, biophotonics has become the research hotspot as an interdisciplinary includes optics and biology. By using optical technology, people can study the microscopic morphology of the cell, which is the basic element of life, explore the chemical composition of the biological elements and diagnose disease. Hence, the study of the interaction of light with biological tissue can have great practical significance.The present thesis studies the application of Monte Carlo simulation in biophotonics. The full text can be divided into two major parts:intensity-based Monte Carlo and electric field Monte Carlo. One of the purposes is to improve the efficiency of the intensity-based Monte Carlo simulation so that it can simulate three commonly used bio-optical detection system. Another major aim is to use the electric field Monte Carlo simulation to study the impact of scattering and absorption on in-vivo microscopic imaging. This study can help people select the appropriate parameters of the optical microscopic imaging system.This thesis consists of six chapters. In the first chapter, we will briefly describe the practical significance of the study of the distribution of light intensity and the field strength in the biological medium, and explain that Monte Carlo simulation is the gold model for the above two questions. In the chapter2, we will study the intensity-based Monte Carlo, and in the chapter3and4, we will study the electric field Monte Carlo.Due to the low computational efficiency of the Monte Carlo simulation, in the second chapter, a new intensity-based Monte Carlo procedure, which combines the hardware and algorithm acceleration, is used to simulate three commonly used optical bio-imaging/detection system. Since the speed of the Monte Carlo simulation has been significantly improved, a dynamic accuracy judgment technology can help determin if the simulation result reached a preset accuracy.The calculation accuracy of Monte Carlo simulation is very high, but it was shelved because of the long computation time. In chapter2, Based on the accelerated Monte Carlo simulation, the perturbation Monte Carlo simulation is improved to be able to handle problem where a large change of scattering coefficient in the overall biological media. In addition, the new perturbation Monte Carlo simulation will also be applied for the Jacobian matrix, which is usually used in diffuse optical tomography.The intensity-based Monte Carlo ignores the polarization and phase information of light. In chapter3, the electric field Monte Carlo is utilized to simulate the propagation of focus electric field in the biological media and study the impact of scattering on the optical focus spot. The simulated light includes vector beams and STED beam.The in-vivo microscopic imaging system is an essential tool for life science research. Due to the scattering and absorption of biological media, the depth limit of current optical in-vivo microscopic imaging system is about1mm. In chaper4, the electric field Monte Carlo is used to calculate the relationship between the optical penetrating depth and the optical wavelength. The suitable wavelength for in-vivo microscopic imaging system can be selected through the simulation result.In chaper5, intensity-based and electric field Monte Carlo are applied to judge the feasibility of non-invasive detection of the Raman signal from biological media. Both phantom and invi-vo experiment are performed to comfirm the feasibility.A summary for this thesis, including inadequacies of the current work and follow-up work plans, is given in the last chaper.