Research On Hyperspectral Detection System Of Space Far Ultraviolet Ionosphere

With the improvement of aerospace science and technology,the scientific research of solar and Earth space atmosphere remote sensing is more comprehensive,and one of the key directions is the study of the upper ionospheric atmosphere remote sensing.The separation layer is mainly located within the range of 48km～965km from the ground.The internal molecules are stimulated by solar high-energy radiation and cosmic rays,and partial ionization occurs,resulting in a large number of free electrons and ions.The distribution changes of these particles have an important impact on solar and earth space weather,radio wave transmission and many other human activities.The exploration of ionospheric hyperspectral imaging and related research are helpful to deepen the understanding of human to the solar and earth space activities.Based on the loading of the ionospheric remote sensing imaging spectrometer of the latest generation in the 21 st century abroad,a detection scheme is designed and a prototype of the ionospheric hyperspectral imager is developed and its performance is evaluated according to the research and application requirements of the far ultraviolet ionospheric imaging detection technology.Principle Prototype adopts the mode of combining edge and sky base for observation,and the observation spectral range is115nm～180nm.The system uses Rowland circular optical system,with off-axis polishing objective as the front telescopic system and single hypertoric flat field holographic grating as the rear spectral imaging system.The optical system in this scheme consists of only two mirrors,with the minimum number.The energy loss is minimal,and adjust to meet the requirements of the design index.In this paper,the working principle,theoretical basis,aberration theory,spectral bandwidth and other relevant theories of the hypertoric grating dispersion-type imaging spectrometer are studied.Code V optical design software is used to optimize the optical system,the photon counting type position-sensitive anode detector based on microchannel plate is selected,the weak light theory is analyzed,and the signal-to-noise ratio of the system theory is analyzed and calculated.The mechanical structure and stray light of the optical system were designed and analyzed by UG and Light Tools software.The theoretical analysis results show that all the indexes of the design scheme meet the requirements of space far ultraviolet ionospheric hyperspectral detection.In the end,the surface shape of the optical element is tested,and the principle prototype of the space far-ultraviolet ionospheric hyperspectral imager is developed and installed.The relevant performance of the principle prototype is evaluated in the vacuum environment.Through the relevant experiments,the spatial resolution of the subsatellite point is better than 10km@840km,and the spectral resolution is 1.97nm@170nm.The signal-to-noise ratio is better than20@10Rayleigh and the stray light is less than 1%@145nm.The design of the space far ultraviolet ionospheric hyperspectral imager has been verified by experiments to be reasonable and feasible.The system has improved the relevant research in the field of far ultraviolet hyperspectral remote sensing in the ionosphere,and laid a foundation for the future space weather science research and the technological transformation of space application in the next step.