采用双自由曲面整形的无掩模光刻照明系统

为了实现无掩模光刻系统所需求的矩形准直平顶激光光束照明，提高照明系统的能量利用率，提出了一种利用双自由曲面整形的照明系统设计方法。根据光程守恒原理和折射定律，推导了积分形式的双自由曲面面形方程；采用数值解法求解积分方程，分别设计了含有双自由曲面的双透镜整形单元和单透镜整形单元的照明系统，使用光学设计软件对两种照明系统进行模拟，得到两种照明系统的照明均匀性在93%以上，能量利用率大于91%。结果表明，两种照明系统均能实现无掩模光刻系统的高均匀性、高能量利用率照明。

Maskless lithography illumination system with double freeform surfaces for beam shaping

In order to achieve the illumination of maskless lithography by rectangular collimated flat-top laser beam and improve the illumination efficiency, a design method of the illumination system using double freeform surfaces shaping unit was proposed. Based on the optical path constant condition and Snell's refraction law, the surfaces equations in integral form of the freeform surfaces were derived. The integral equations were solved by numerical calculation. The illumination systems using two-lens shaping unit and single-lens shaping unit which included double freeform surfaces were designed and simulated by optical design software. The simulated results show that the uniformity is over 93% and the illumination efficiency is over 91%. It is illustrated that the two kinds of shaping unit could meet the requirements of the illumination of maskless lithography.