基于非球面镜像差效应的长焦深高斯光束均匀化光学系统设计

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

近红外高斯激光束在强激光与材料相互作用、激光清洗、激光燃烧诊断等热点研究领域中发挥着重要的作用。然而,高斯光束能量分布的不均匀性阻碍了这些领域的深入发展。为提高工作效率和测量精度,实际应用中往往期望光束能量在较大工作距离内呈均匀分布,但现有光束整形方法无法同时满足长焦深和高激光耐受功率要求。为此,本文基于非球面像差效应提出并设计了一种新型长焦深高斯激光束均匀化光学系统,系统由非球面光束均匀化系统和球面长焦准直系统两部分组成,所有透镜均采用熔融石英并在其表面镀有增透膜,能够实现99.9%的光学系统传输效率。系统工作波段为1064 nm,工作距离为1000 mm,系统总长为135.2 mm,耐受激光功率不小于300 W。设计结果表明:整形后的平顶高斯光束有效焦深为±100 mm,光束均匀性≥95%,会聚角为17.52 mrad,能够满足上述应用场景的实际需求。本文设计的光束整形系统相比于其他激光光束均匀化系统,具有结构简单、易于加工、成本低、焦深长、耐受激光功率高、光束均匀化效果好的特点。

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.