月基地球等离子体层极紫外成像仪的光学设计

Optical design of moon-based earth's plasmaspheric extreme ultraviolet imager

依据地球等离子体层在30.4nm的辐射特性,首次以月球为观测点进行地球等离子体层极紫外波段成像观测方法研究。确定了在月球表面使用的极紫外成像仪的技术参数,给出了视场角为15°、角分辨率为0.1°、入瞳面积>70cm2的极紫外成像仪的结构形式,采用单球面多层膜反射镜与球面微通道板光子计数成像探测器相结合的方式设计了极紫外成像仪。对设计的极紫外多层膜光学系统成像仪进行光线追迹,弥散斑半径分别为0.210mm(0°视场)、0.204mm(3°视场)、0.204mm(5°视场)、0.207mm(7.5°视场),对应的角分辨率为0.08°,弥散斑在不同视场角度基本均匀,其结果满足设计要求。该仪器可在月球表面工作,获得视场范围为15.0RE,覆盖地球等离子体层主要区域,空间分辨率为0.10RE,可以很好地观测到地球等离子体层主要细节,为从外部进行地球等离子体层观测提供了一种高质量的成像观测方法。

According to the 30.4 nm radiation properties of the earth＇s plasmasphere,an earth＇s plasmaspheric extreme ultraviolet imaging method based on the moon was researched for the first time.The technical parameters of the extreme ultraviolet imager used in the lunar surface were determined,and its field of view is 15°,angular resolution is 0.1° and the entrance pupil area is larger than 70 cm2.By combining a single spherical multilayer mirror and a spherical microchannel plate photon counting imaging detector,the extrame ultraviolet imager was designed.The ray tracing of designed extreme ultraviolet imager with multilayer optics was also performed.Results show that the radii of the blur spots are 0.210,0.204,0.204,and 0.207 mm respectively at 0,3,5,and 7.5°,which are basically identical at different field of views.In woking on the lunar surface,the imager has a vision scope of 15.0 RE to cover the main body of the earth＇s plasmasphere and a spatial resolution of 0.10 RE that can reveal the main details of the earth＇s plasmasphere.It provides a high quality imaging method for the observation of earths plasmasphere.