Stray Light Characteristics And Suppression In Space-borne Doppler Asymmetric Spatial Heterodyne Interferometer

Wind field is an important parameter to characterize atmosphere.The detection of wind field in the middle atmosphere of 60-90 km is of great significance in the smooth progress of space missions,space scientific research,and accurate weather forecasting.Based on the Doppler effect,the Doppler Asymmetric Spatial Heterodyne Interferometer measures the wind speed by detecting the Doppler frequency shift of the spectral line.It has high sensitivity,high spectral resolution,large luminous flux,and low processing and adjustment accuracy requirements.The instrument adopts the limb-viewing mode,which is not limited by geography and weather,and can perform all-weather remote sensing detection on a global scale,and has the characteristics of high spatial coverage and high vertical resolution.However,in this observation mode,the low-altitude atmospheric background radiation with strong energy is close to the observation field,which is easy to cause serious stray light problems.In order to ensure the wind measurement accuracy of the instrument,it is necessary to analyze the stray light of the spaceborne Doppler Asymmetric Spatial Heterodyne Interferometer and design the suppression structure.This paper takes the Doppler Asymmetric Spatial Heterodyne Interferometer system for wind detection in the middle atmosphere(60～90km)as the research object,analyzing its stray light sources and characteristics and designing the suppression structure.Firstly,according to the principle and observation mode of the Doppler Asymmetric Spatial Heterodyne Interferometer,the stray light it faces is divided into stray light outside the field of view and stray light in the field of view.The stray light outside the field of view is the atmospheric background radiation,and the stray light in the field of view is mainly the ghost image and the non-working order energy of the blazed grating.Secondly,in order to suppress stray light outside the field of view,the atmospheric background radiation received by the instrument under the working orbit and observation geometry is calculated.By simulating the instrument orbit and observation geometry,an observation model is established,and orbit data such as the latitude and longitude of the observation point 、 the target point 、 sub-Sun are output.The characteristic observation lines were selected to calculate the atmospheric background radiation at the vernal equinox,summer solstice,autumn equinox,and winter solstice under 81 atmospheric environments(9 aerosol types,9 surface types),respectively.The results show that when the Navy Maritime aerosol is selected and the surface is covered with cloud deck,the ambient background radiance is the strongest,and the maximum radiance appears in the middle of the orbital diurnal hemisphere.In order to ensure that the instrument can work all-weather,the strongest atmospheric background radiation faced by the instrument at-30～100km(negative value means that the observation line intersects the earth)is calculated.The results show that the atmospheric background radiation continues to increase with the decrease of altitude,and the atmospheric background radiation below 20 km will reach 1-8 times of the average airglow radiance in the observation range.