Optical System Design for Gaussian Beam Uniformization with Long Focal Depth Based on Aberration Effect of Aspheric Mirror

Abstract

Near infrared Gaussian laser beams are crucial in many research studies,such as the interaction between intense laser and materials,laser cleaning,and laser combustion diagnostics.However,the non-uniformity of energy distribution of Gaussian beams hinders the further development of these fields.To improve cleaning efficiency and measuring accuracy,beam energy is typically expected to distribute uniformly within a larger working distance in practical applications.Nevertheless,the current beam shaping methods cannot satisfy requirements of long focal depth and high laser power tolerance simultaneously.Therefore,a novel optical system of Gaussian beam uniformization with long focal depth is proposed and designed based on the aberration effect of aspheric surface lens,which comprises an aspheric beam uniformization system and a spherical long focal collimation system.All lenses are fabricated with fused quartz and coated with antireflective film on the surface,which can achieve a 99.9%transmission efficiency in the optical system.The working wavelength of the system is 1064 nm,the working distance is 1000 mm,the total length of the system is 135.2 mm,and the laser power is higher than 300 W.The design results show that the effective focal depth of the shaped flat-topped Gaussian beam is±100 mm,the uniformity of the beam is better than 95%,and the convergence angle is 17.52 mrad,which satisfy the requirements of the abovementioned application fields.Compared with other laser beam uniformization systems,the beam shaping system designed in this study possesses a simple structure and affords easy processing,low cost,long focal length,high laser power tolerance,and good beam uniformization.