[f-θ]透镜是激光标刻系统中最为重要的组成部分, 它的性能将直接影响标刻机的标刻精度。设计的[f-θ]透镜波长为[0.65]μm的单色光, 设计时引入负的桶形畸变, 校正系统的场曲, 使匹兹伐尔场曲为零, 轴外和轴上像质一致, 整个像面成平面, 且系统波像差小于[λ4]。把入瞳放置在物方焦点处, 形成像方远心光路, 主光线通过[f-θ]透镜后平行于光轴射出, 主光线在像面上的交点高度不变, 描过程实现线性扫描, 从而保障扫描精度。通过初级像差分析和已有的光学镜头库, 确定[f-θ]透镜的初始结构参量, 然后利用ZEMAX软件进行优化设计, 得到由四片普通球面透镜构成的系统, 该系统结构紧凑、焦距小, 聚焦性能接近衍射极限, 并且像面照度分布均匀、能量集中且相对畸变小, 满足标刻要求。

f-θ lens is the most important parts of laser marking system, its performance will affect the marking precision of laser marking machine directly. The design of f-θ lens is monochromatic light with 0.65 μm wavelength, negative barrel distortion is introduced in the design, field curvature is corrected and the Zifaer field curvature is equal to zero, image quality off axis and on axis is uniform, image plane is plane and the wave front aberrations is less than λ/4. The entrance pupil is placed at the object focus, so the image telecentric beam path is formatted, main light exited through the lens is parallel to the optical axis, the height of intersection points on image plane of main light are invariant, a linear scanning process is achieved in order to ensure scanning precision. The initial structure parameters of the lens are determined through the analysis of the primary aberration and the existing optical lens library, and then optimizes the design through ZEMAX software, the system with four pieces of ordinary spherical lens is obtained. This system is compact, short focal length and its performance is within diffraction limit, and has uniform illumination distribution, concentrated energy and small relative distortion, which meets marking requirements.