用于光束匀滑的连续相位板设计
Design of the continuous phase plates for beam smoothing
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摘要: 为了满足大型激光装置中驱动源聚焦光斑的均匀光强分布、高能量利用率和小旁瓣等特殊要求,提出了采用追迹法和改进G-S算法相结合的连续相位板设计方法。进一步采用衍射积分方法模拟了该连续相位板的光学性能,计算得到其产生的焦斑具有类似24阶超高斯分布,其顶部光强均方差σRMS=0.35%、顶部调制度γ=1.33%、能量利用率η=99.79%。结果表明,该方法不仅具有追迹法计算简单、运算量小的优点,而且克服了G-S算法容易陷入局部最优的缺点。采用该方法设计的连续分布,解决了加工难题,从而也提高了相位板的匀滑性能。Abstract: Aiming at the special requirements such as homogeneous intensity, high ratio of applied energy and small sidelobe for the focal spot of drive source in large-sized laser device, a hybrid method based on geometrical transformation and modified Gerchberg-Saxton (G-S) algorithm was proposed to design continuous phase plates(CPP).The performance of the CPP was verified by means of diffraction numerical integrating method and the result showed that the CPP obtained good 24th-order super-Gaussian fit with diffractive efficiency up to 99.79%, top mean square error of 0.35% and top modulation of 1.33%.This method is fast and avoiding the shortcoming that the G-S result is easy to trap in local optimum.Moreover, the designed plate is fully continuous, so the plate is easy to be fabricated and improves the smoothing performance of the plate.
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