Design of a long depth of focus Gaussian beam shaping system via aspheric lenses

This paper presents a beam shaping system that uses a Galilean beam shaper. The light mapping function and the aspherical coefficient, which determines the characteristics of the aspheric lens, are derived based on the law of conservation of energy. Furthermore, optical software (i.e., ZEMAX) was utilized to simulate the design of the shaping system. In addition, a spherical collimation system is introduced to achieve the shaping system with long depth of focus. The results show that the output flat-top beam has the uniformity over 90% within the 300mm depth of focus range and the divergence angle no more than 0.6°, which is in line with the theoretical expectation. Compared to the previous works, our beam shaping system is characterized by long depth of focus, simple structure and good beam shaping effect, which makes the present shaping beam more flexible for the application in the field of laser processing.本文提出了一款搭载伽利略光束整形器（Galilean beam shaper）的光束整形系统。基于能量守恒定律，推导得到了决定非球面透镜（aspheric lens）特性的光映射函数与非球面系数（aspherical coefficient）。此外，本研究借助光学软件ZEMAX对该整形系统的设计进行了仿真分析。为使该整形系统具备长焦深特性，本文还引入了球面准直系统。结果表明，所输出的平顶光束（flat-top beam）在300mm焦深范围内的光束均匀性超过90%，发散角不超过0.6°，与理论预期相符。与既往研究相比，本光束整形系统具有焦深长、结构简洁、整形效果优异的特点，使得该整形光束在激光加工领域的应用更具灵活性。