大尺寸衍射光学元件的扫描离子束刻蚀

Ion beam etching of large aperture diffractive optical elements

总结了大尺寸衍射光学元件离子束刻蚀技术的研究进展。针对自行研制的KZ-400离子束刻蚀装置,提出了组合石墨束阑结构和多位置分步刻蚀策略来提高离子束刻蚀深度的均匀性,目前在450mm尺寸内的刻蚀深度均匀性最高可达±1%。建立了针对多层介质膜光栅的衍射强度一维空间分布在线检测系统以及用于透射衍射光学元件离子束刻蚀深度的等厚干涉在线检测系统,实现了对大尺寸衍射光学元件离子束刻蚀终点的定量、科学控制,提高了元件离子束刻蚀工艺的成功率。利用上述技术,成功研制出一系列尺寸的多层介质膜光栅、光束采样光栅、色分离光栅以及同步辐射光栅等多种衍射光学元件。

Ion beam etching technologies for developing large aperture Diffractive Optical Elements（DOEs） were reviewed.To meet the requirements of large aperture DOEs in high-power laser systems,an integrated graphite mask for ion beams and a multi-position etching strategy were investigated for a self-established KZ-400 etching facility to improve the uniformity for ion beam etching and the uniformity of ±1% for ion beam current along the major axis of the ion source was achieved in a range of 1430 mm.On-line optical measurement methods and experimental setups for Multilayer Dielectric Gratings（MDGs） and transmission DOEs were presented to measure the 1D spatial distribution of diffraction intensity and the ion beam etching depth based on fringes of equal thickness,respectively,by which the quantitative control of ion beam etching for large size DOEs was completed.Based on above techniques,a series of large aperture DOEs,especially MDGs with diffraction efficiencies more than 95% at 1 064 nm,beam sampling gratings,color separation gratings and beam sampling gratings for synchrotron radiation were fabricated successfully.