Research On Single-mode Laser Beam Shaping Method

Since the advent of laser,it has been widely used in practical production and life because of its good monochromatism and directivity.However,for a single-mode laser,its energy distribution exhibits a non-uniform Gaussian distribution.Therefore,in practical applications,due to the non-uniformity of the beam energy,it will directly lead to the interaction between the laser and the material,thereby limiting the application of the laser in photolithography,processing,welding,and target simulation.Therefore,it is of great significance to shape the Gaussian beam into a flattened beam.In this paper,the single-mode Gaussian beam shaping was researched by using aspherical beam shaping and anti-Gaussian coating beam shaping,the lossless beam shaping and far-field flattened beam with large aperture and parallelism were achieved respectively.The main research contents can be Summarized as follows:Firstly,the theory of Gaussian beam shaping technology was studied in depth.Especially the characteristic parameters and propagation laws of single-mode Gaussian beams and several types of flattened beams were deeply deduced and analyzed.Then the specific input and output beam distributions were selected to establish the mapping function.The surface parameters of the two even-order aspheric beam shaping systems were fitted and calculated according to the law of conservation of energy,and the beam uniformity was calculated through the optical design software,which is used to verify the correctness of the design.Then according to the ZPL macro program design in ZEMAX optical design software,a set of even-order aspherical beam shaping system was designed,and the uniformity was simulated to verify the correctness of the design.Then a set of 4~6times continuous expansion beam expander system was designed.The system can expand the incident beam of any aperture to the specified output aperture,which is used to match the use of the shaping system,and at the same times calculated and drew the zoom curve.In order to solve the problem of poor uniformity caused by the divergence of the outputing beam,a set of fixed collimation beam expanding system was designed,which effectively increased the uniformity effect distance.And finally for the three sets of systems,the corresponding mechanical structure were designed to facilitate the actual processing and installation.Finally,in order to obtain large-aperture and high-parallel uniform far-field beams,an anti-Gaussian beam shaping system was designed under the conditions of a specific light source and a specific output aperture,and the uniformity of the designed results was actually implemented in a laboratory environment,which is to verify the correctness of the design results.The reasons for the uniformity of thebeam were analyzed and summarized as well.Among them,the stability of the light source,the interference diffraction phenomenon and the influence of the stray light on the uniformity were analyzed in detail.Therefore the structure of the anti-Gaussian coating beam shaping system was optimized and improved.