Research On The Propagation Characteristics And Generation Theory Or Technology Of Multistage Non-diffracting Beam

The cross-sectional light field distribution of the non-diffracting beam subject to the first zero-order Bessel function,and always maintains the focus state transmission in free space.The intensity and size do not change with the transmission distance.The non-diffracting beam can self-reconstruction and quickly recover to the original optical characteristics within a relatively short transmission distance after encountering obstacles.Therefore,it has been widely studied and applied in the fields of laser micro-processing,optical collimation and imaging,optical precision detection,and optical micro-manipulation.However,the current research on non-diffracting beam mainly focuses on singlestage non-diffracting beam.Compared with bipolar or multistage non-diffracting beam,it not only has the advantagment of singlestage,but also shows a wider application fields of biomedicine,atomic physics and other fields.Thus,this paper will study the formation mechanism,methods and influencing factors of non-diffracting beam from singlestage to multistage.The main research contents are as follows:Basic theoretical research on non-diffracting beam: including the theory of geometric optics and diffraction optics.Based on the theory of geometrical optics and the axicon method,the relationship between the maximum distance of non-diffraction propagation or the size of the central spot among the incident wavelength,the bottom angle of the axicon,the radius and the refractive index of the axicon are derived from singlestage to multistage non-diffracting beam respectively.Based on the theory of Fresnel diffraction,combined with the principle of wavelet coherence superposition mathematical integration and phase stabilization method,the integral expression distribution of the spatial light field after a plane wave perpendicularly incident to an axicon lens is derived.The distribution of axial light intensity,radial light intensity and transverse light intensity along different transmission distances of non-diffracting beam are simulated respectively.On this basis,the singlestage axicon lens is extended to bipolar or multistage,and then bipolar or multistage non-diffracting beam are generated,which focusing on the coupling of light intensity in the interference superposition region.The oscillation period and evolution process of the local hollow beam are analyzed on basis of the Talbot effect.Transmission and conversion of non-diffracting beam: including the transmission and conversion of singlestage,bipolar,multistage axicon lens.As well as the oblique incidence,obstacle occlusion and beam self-reconstruction,transmission and conversion of telescope optical system.Based on the axicon method,the propagation and conversion characteristics of non-diffracting beam after collimating laser beam incident vertically to single,bipolar and multistage axicon lens are analyzed on theoretically and experimentally respectively.The generation differences between single and multistage non-diffracting beam in the interference overlap region are analyzed emphatically.At the same time,the propagation characteristics of non-diffracting beam after collimated laser beams incident at a certain inclination angleto axicon lens are investigated,and the relationship between the incident inclination and the splitting degree of the beam spot is obtained.Based on the principle of Babinet and energy flow,the process of self-recovery and self-reconstruction of non-diffracting beam is studied systematically,and the relationship between the size of obstacles and the self-recovery process is obtained.Based on the axicon method,the telescope optical system was equipped,a non-diffracting beam system is constructed by adjusting the focal length of the lens of the telescope optical system.The relationship between the characteristics of the new non-diffracting beam and the transformation of the telescope optical system lens parameters was constructed,which reduces the limitation of the propagation characteristics of the original non-diffracting beam depending on the structural parameters of the optical device.The influence of the generation of non-diffracting beam: including the geometric parameters such as the bottom angle and radius of the axicon lens,the physical parameters such as the incident wavelength and the refractive index of the axicon lens.As well as the influence of the axicon lens processing deviation on the propagation characteristics.Based on the axicon method,the effects of the incident laser wavelength,the bottom angle of the axicon lens,the radius and the refractive index of the axicon lens on the spatial distribution or intensity of the non-diffracting beam are analyzed theoretically and experimentally respectively.The differences in the five main methods of generating non-diffracting beam are compared and analyzed systematically.Based on the processing technology of axicon lens,the symmetry deviation and asymmetric deviation model are established,such as concave,convex and hyperbolic dome in the symmetry deviation.The amplitude transmittance function is derived based on the contour of the axicon lens surface.The influence of the deviation form on the light field distribution,intensity and transmission characteristics of the non-diffracting beam are simulated espectively.In the deviation of asymmetric machining,the relationship between the processing deviation and the azimuth angle of the axicon lens is established,and then the amplitude transmittance function is deduced.The difference between the machining deviation of symmetrical and asymmetric are analyzed based on the Fresnel diffraction theory.This study provides a theoretical basis for analyzing the influence of the axicon lens processing errors on the propagation characteristics of the non-diffracting beam.At the same time,it has important guiding significance for further perfecting the diffraction field theory of the non-diffracting beam and broadening its engineering application scope.This paper systematically studies the formation mechanism,transmission and conversion,generation of non-diffracting beam from single stage,bipolar to multistage,and lays a theoretical foundation for the application of non-diffracting beam in practical engineering,which has important guiding significance for the design,optimization and evaluation of non-diffracting optical systems with controllable parameters.