无缝光谱仪用紫外透射闪耀光栅的制作

Fabrication of Ultraviolet Transmission Blazed Grating for Slitless Spectrometer

无缝光谱巡天是如今国际天文学研究的重点方向,相比较地基巡天任务,空间巡天可获取更多紫外波段与红外波段的光谱信息,其发展受到色散元件的制约,针对紫外波段的核心色散元件|紫外透射闪耀光栅开展了一系列研究.通过全息干涉光刻产生图形,离子束垂直刻蚀将图形转移至基底形成光栅掩模,利用光栅掩模对倾斜离子束的遮挡作用,使得槽底不同部位受到离子束的轰击通量不同,从而获得非对称的槽形结构.实验分析了倾斜离子束刻蚀中沉积物的主要组成以及对槽形和闪耀角度的影响,并在去除沉积物影响的情况下,成功制作了线密度为333 lines/mm,闪耀角度分别为13.2◦、10.5◦的紫外透射闪耀光栅,峰值衍射效率分别可达理论值的88%以及92%,为制作高衍射效率紫外透射闪耀光栅奠定了基础.

Slitless spectral sky survey is the key direction of international astronomical research.Compared with ground-based sky survey,space sky survey can obtain more spectral information in ultraviolet and infrared bands,and its development is restricted by dispersive elements.A series of researches have been carried out on ultraviolet transmission blazed grating,the core dispersive element of ultraviolet band.The pattern is generated by holographic interference lithography,and the pattern is transferred to the substrate by ion beam vertical etching to form a grating mask.By using the grating mask to block the inclined ion beam,different parts of the groove bottom are bombarded with different ion beam fluxes,so as to obtain asymmetric groove structure.The main composition of the deposit and its influence on the groove shape and blaze angle in the inclined ion beam etching are analyzed.Under the condition of removing the influence of sediment,the ultraviolet transmission blazed gratings with linear density of 333 lines/mm and blazed angle of 13.2◦and 10.5◦were successfully fabricated.The peak diffraction efficiency of the gratings can reach 88%and 92%of the theoretical value respectively,which lays a foundation for the fabrication of ultraviolet transmission blazed gratings with high diffraction efficiency.