Design Of Flat-top Beam Shaping System Based On Gaussian Distribution Beam

Laser has been rapidly applied in the fields of laser cutting,marking,cladding,quenching,etc.due to its advantages of high monochromaticity,low divergence angle,high coherence and high energy density.However,the uneven energy distribution of the single-mode laser beam has restricted its development in high-precision processing,measurement,and biomedicine fields.Therefore,laser shaping technology is required to shape the beam with a Gaussian distribution of spatial illuminance into a flat straw hat-shaped beam to ensure the verticality of the cutting surface or the edge of the perforated surface to achieve high-quality processing.Based on the transformation requirements of beam illuminance distribution in laser processing,this paper studies the fundamental mode Gaussian laser shaping optical system,and completes the development of numerical integration solving algorithm and automatic optimization design based on ZPL programming.Several tasks that have been completed in this topic include:The theoretical models of Gaussian beams and flat-top beams are studied,and the transmission characteristics of the flat-top beams in free space and the equivalent transformation relationship are analyzed.Combining shaping requirements,cost,design difficulty and other factors,select the flat-top beam model and shaping method.By defining the evaluation criteria of the uniformity of the beam illuminance,it provides a theoretical basis for the judgment of the shaping effect.(2)The solution algorithm based on numerical integration is studied.According to the principle of conservation of energy,the mapping relationship between the incident beam and the light distribution of the outgoing beam is established;according to the principle of geometric optics,the surface shape data formula of the double aspherical system is derived.Combine the beam mapping relationship with the surface shape formula through Matlab programming to calculate the structural parameters of the shaping system.Then bring the data into the optical software for simulation and compare with the design index.(3)The development of the automatic optimization program for the shaping system based on ZPL programming was studied,and the shaping system design of the flat-top linear spot and the variable-diameter flat-top round spot was completed.Using semiconductor lasers,the initial structure formulas of collimating cylindrical lenses and Powell prisms are derived,and the initial structure is optimized by ZPL programming,and a linear spot with a flat top illuminance in the fast axis direction is obtained;a collimated fiber laser is used,based on the lens module The formula of the initial structure of the zoom optical system is derived by the chemical design method,and the initial structure is optimized by ZPL programming to obtain a circular spot with continuously adjustable size and uniform illuminance distribution.(4)For the reshaping zoom reshaping optical system,use ZPL programming to obtain cam curve data;use ZEMAX to bring in errors to simulate the impact of the reshaping system under real conditions such as processing and assembly;finally,carry out tolerance and assembly analysis on the system to ensure the system’s feasibility Processability.(5)Design experiments to verify the shaping theory based on ZPL programming optimization,and obtain relatively ideal experimental results.