Applications Of Ray Tracing In Designing Of Light Beams,Simulation Of Optical Force And Imaging Of Cells

How to design light beams with novel features and their propagating properties are of great importances in optics.The traditional wave-optics method is hard for us to design light beams according to the requirement in experiments,and is not intuitive and purposeful enough as well.In this thesis,we investigated three kinds of applications of modern geometrical optics,including the designing of structured light beam,the calculation of optical force,and the simulation of optical imaging.The major contents are detailed as below:(1)The developments of modern geometrical optics are systematically investigated.Twoimportant models of light rays,including the “ray tube model” and “ stable aggregateand flexible element(SAFE)model”,are introduced.The applications of these twomodels in beam designing are also studied.(2)The propagation of the fundamental Gaussian beam in both paraxial and nonparaxialregimes are characterized by ray tube model.Since the fundamental Gaussian beamis the most typical and the most widely-used light beam in field of laser researches,its propagation property has attracted lots of studies.The geometrical optics modelin this thesis gives an intuitive and precise method to describe the propagation ofnonparaxial Gaussian beam,which gets rid of the complex mathematical processesof traditional wave optical method.(3)The propagation properties of nondiffracting beam,self-accelerating beam andautofocused beam are represented by SAFE model.Furthermore,their self-healingproperties are explored using rays.Different from the wave optics' method,structured light beam can be designed purposefully by ray-optical Poincaré spheremethod.(4)Ray-tracing methology is the core of application of geometrical optics.Quaternionsare proposed to trace the directions of reflected and refracted.This method simplifiesthe mathematical processes of traditional solid geometry ray-tracing method.Thequaternions can be used to trace rays on any irregular geometric surface,and makesray tracing easier and extend the applications of Geometrical optics.This work is thefoundation of the force and imaging simulations.(5)In this thesis,optical forces for highly focused Gaussian beam and Airy beam aresimulated according to ray tracing.These simulations demonstrate the simplicity andimmediacy of ray-optics method.Our simulation results are consistent with that of inexperiments.Theoretical analysis of the optical force for light beams helps usunderstand the experimental phenomena,and design optical manipulation systemswith novel features including higher trapping quality.(6)The procedures of optical imaging are also simulated by ray tracing.In the final partof this thesis,the simulated difference imaging fits well with the experimental results.The researches in this thesis provide an intuitive and reliable train of thought for designing structured beams with novel properties,which is the foundation of the further applications of these beams.Both the descriptions of beam propagation and calculations of its optical force are integrated in the framework of geometrical optics.In force analyzing,focused Gaussian beam and Airy beam are presented as examples to demonstrate the simplicity and immediacy of ray-optics method.In addition,the effect of illumination on microscopy are analyzed by using ray-tracing method,providing a reasonable method to design the lighting pattern for difference imaging experiment.Some methods and research results in this thesis would have practical and potential values in the field of optics and biomedical science.It is expected that this thesis could provide some helps for the researches in related fields.