通过对多台阶衍射光学元件(MDOE)刻蚀工艺中的误差分析,提出了一个反映整体刻蚀误差的参数——误差偏度。重点研究了误差偏度的变化对多台阶衍射光学元件光束整形效果的影响,发现在误差偏度曲线中存在一个能使刻蚀误差影响减弱的平坦区间。提出了在刻蚀工艺上以控制刻蚀深度来改善多台阶衍射光学元件器件实际照明效果的一种方法。实验结果表明,经过工艺优化后的MDOE的光场参数峰值(PV)下降了近30%。

From the error analysis of multi-level diffractive optical elements (MDOE) in etching process, the parameter of error skewness was suggested to reflect the overall etching error. The variation of error skewness versus the beam shaping effect of diffractive optical elements is investigated, and a flat interval which can reduce the impact of etching error existed in the curve of error skewness. According to these curves, a technical method for improving the factual illumination quality of MDOE was proposed by controlling etching depth. The experimental results show that the peak value (PV) of the optical field parameter reduces about 30% after the technical optimization.