提出一种通用的抛物带式矩形光斑积分镜,建立了分段抛物线匀化模型,推导了满足超精密车削加工的分段抛物线方程。该积分镜解决了传统直线带式积分镜在积分方向上匀化宽度太小的问题,可获得远大于输入光斑直径的匀化宽度,同时分析了该积分镜分割段数对输出光斑均匀性的影响。利用高斯光束行波传输方程,计算回转方向上的离焦光斑尺寸,解决了采用几何光学方法获得离焦光斑尺寸误差大的问题。设计了输出光斑尺寸分别为100 mm×3.2 mm和14 mm×3.3 mm的积分镜,采用Zemax和SolidWorks软件进行仿真,仿真得到的光斑尺寸分别为100.2 mm×3.2 mm和14.2 mm×3.3 mm。加工了14 mm×3.3 mm的积分镜,在3 kW光纤激光器上进行实验,测得的光斑尺寸为14.3 mm×3.3 mm,匀化方向均匀性为90%,满足激光加工应用要求。

Herein, a versatile parabolic band integrating mirror for a rectangular spot is proposed. A segmented parabolic equation satisfying the ultraprecision turning process is derived using an established segmented parabola homogenization model. Using the integrating mirror, homogenization width in the integrating direction larger than that of the traditional rotating segmental linear integrating mirror can be obtained, which is considerably larger than the input spot diameter. The influence of the number of integrating mirror segments on the uniformity of the output spot is analyzed. To avoid large deviation errors caused by a geometric method, the transmission equation for traveling Gaussian waves is used to calculate the defocused spot size in the rotation direction. Two integrating mirrors with output spots of 100 mm×3.2 mm and 14 mm×3.3 mm are designed and simulated by SolidWorks and Zemax, respectively, and the simulated spot sizes are 100.2 mm×3.2 mm and 14.2 mm×3.3 mm. The 14 mm×3.3 mm integrating mirror is processed and tested with a 3-kW fiber laser. The spot size is measured to be 14.3 mm×3.3 mm, and the uniformity of the homogenization direction reaches up to 90%, which satisfies the application requirements for laser processing.