太阳极紫外成像光谱仪光学系统设计与分析

针对太阳极紫外成像光谱仪的应用目的与工作环境,设计了一种太阳极紫外成像光谱仪的光学系统.该系统由望远系统、狭缝、光栅与探测器组成.望远系统采用离轴WolterⅡ型结构,入射光掠入射进入系统,具有光谱范围宽、稳定性高、克服恶劣空间环境能力强等优点.扫描镜采用平面反射镜,成像质量不随扫描角的改变而改变.分光光栅采用超环面3 600lines/mm变间距光栅,与超环面等间距光栅相比,具有成像质量高、光谱分辨率高、缩短系统长度的优势.工作波段为17.0～21.0nm,可满足探索温度在5.8≤log T≤6.3区间的宁静日冕的需要.视场为1 228″×2 400″,空间分辨率达到0.8arc second/pixel,光谱分辨率约为0.001 98nm/pixel,总长度不超过2.5m.计算了望远系统的理论有效面积,给出了望远系统的成像质量与实际的视场.系统整体的成像质量、光栅的谱线弯曲与谱带弯曲,均满足实际应用要求.

Design and Analysis of Optical System for Solar Extreme-ultraviolet Imaging Spectrometer

A kind of optical system of solar extreme ultraviolet imaging spectrometer is designed aiming at solar extreme ultraviolet imaging spectrometer′s application objective and working environment. The optical system consists of a telescope, a scanning mirror, a slit, a grating and a detector. Wolter typeⅡ configuration is chosen for the telescope, light enter the system by grazing incident, so it has wide working band, and is highly stable, practicable to withstand the rigors of space flight. A plane mirror is chosen for scanning mirror, so the imaging quality would not change with scanning angle. A toroidal varied line space grating which is 3 600 lines/mm is chosen for dispersion. Compared with toroidal uniform line space grating, it superiors in imaging quality, spectral resolution and shortening system length. The working band of the optical system is 17.0~21.0 nm which could meet the probe of the quiet corona in the temperature region 5.8≤log T≤6.3. The field of view is 1228″× 0.8″, the spatial resolution is 0.8 arc sec/pixel, the spectral resolution is about 0.001 98 nm/pixel, the total length is under 2.5 m. The telescope system′s effective area is calculated, and the telescope′s imaging quality and real field of view are given. The imaging quality of whole system, the smile and keystone of grating can satisfy the application demand.