自由电子激光器用极紫外波段平面变栅距光栅

针对极紫外波段自由电子激光器(大连相干光源,DCLS)对高分辨能力平面变栅距光栅的需求,基于光程差以及像差原理构建了极紫外平面变栅距全息光栅。采用改进的局部优化算法给出了平面变栅距光栅的记录参数,利用全息曝光技术在硅光栅基底上制作了中心刻线密度为600gr/mm、占宽比为0.46、槽深为550nm、有效刻划面积为30mm×30mm的极紫外平面变栅距全息光栅。采用Littrow衍射法测量了平面变栅距光栅的刻线密度,并基于像差理论分析了平面变栅距光栅的理论分辨能力。结果表明:制作的600gr/mm平面变栅距光栅在有效面积内的刻线密度误差小于0.175gr/mm,在极紫外波段(50~150nm)的分辨能力大于12 000,满足自由电子激光器的设计要求。提出的设计及制作方法为制作高质量平面变栅距光栅提供了理论及技术保障。

Plane holographic varied-line-space grating for DCLS in EUV region

According to the demands of a free electron laser(Dalian Coherent Light Source, DCLS) at extreme ultraviolet (EUV) for high resolution plane holographic varied-line-space grating, a plane holographic varied-line-space grating was fabricated based on optical path difference and aberration principle. By using the improved local optimization algorithm, recording parameters of the varied-line-space grating were calculated. The varied-line-space grating at EUV with a center groove density of 600 gr/mm, a duty cycle of 0.46,a groove depth of 550 nm and an effective score area 30 mm×30 mm was fabricated on a silicon substrate by using the holographic method. The groove density of the varied-line-space grating was measured by Littrow diffraction and its theoretical resolution was analyzed by aberration theory. The results show that the groove density in an active area is less than 0.175 gr/mm, namely the resolution is far above 12 000 in 50-150 nm EUV region, which meets the demand of the DCLS. It concludes that these theories and research findings provide theoretical and technical supports for improving the quality of plane varied-line-space gratings.