Focusing Characteristics Of Vector Light Field

Vector beams have been the focus of research in the field of optics in recent years due to their special polarization.Common scalar beams,such as linearly polarized,circularly polarized,and elliptically polarized light,have the same polarization state at each point on the beam cross section.The polarization state of the vector beam is symmetrically distributed along the axis,and the polarization state at each point is different.Because of its special polarization state,it has unique charm in many fields.For example,tightly focusing radial polarized light has a strong vertical component of the focusing field;tightly focusing azimuthally polarized light has almost zero vertical component of the focusing field,and its focusing spot is like a donut;Tightly focusing the azimuthal first-order vortex polarized light will result in a smaller focused spot than radial polarized light.Based on these focusing characteristics,vector beams have a wide range of applications in optical tweezers,optical storage,lithography,and highresolution microscopy.The polarization characteristics and phase modulation of vector beams are used to study their focusing characteristics,so that they can have wider application prospects in many fields.At present,the research on vectors is still hot,and there are many scientific and technical problems to be solved.In this thesis,the focus field of the vector beam is calculated and analyzed.The polarization and phase of different vector beams are modulated.The minimum focus spot and multi-focus spot are calculated theoretically.The main contents are as follows:1.The research background and significance of vector beams are introduced,and the current research status of vector beam focusing characteristics is introduced.The calculation method of light field is introduced.For example,based on Richards-Wolf's vector diffraction theory,the theory of plane wave angle spectrum is introduced in detail.2.The principle and generation method of vector beam are introduced.The generation of vector beam is divided into intracavity method and extracavity method.The focusing characteristics of different polarized light are analyzed and calculated,and linearly polarized light,cylindrical vector beams(CVB),cylindrical vector vortex beams(CVVB),and perfect cylindrical vector beams(CVVB)are compared.Focusing spots of Perfect Cylindrical Vector Beams(PCVB)and Perfect Cylindrical Vector Vortex Beams(PCVVB);the focus characteristics of the perfect azimuthal vortex beams were further calculated and analyzed.3.Based on the plane wave angle general theory,through pure phase modulation,multiple focused light spots are generated,and the movement of the light spots in the two directions of the focal plane X and Y is controlled and dynamic.The multi-focal spot of the vector beam is modulated to change its position and polarization direction,respectively.4.Set up an experimental platform to measure the focused spot of the perfect angular vector vortex beam and angular vortex beam and processing the sample through photolithography.