Fig. 1. Schematic diagram of HDI data product generation

Fig. 2. Schematic diagram of limb observation atmospheric backscattering

Fig. 3. Ray trace of fore cylindrical lens and collimating lens

Fig. 4. Spatial spot diagrams of fore collimator lens

Fig. 5. Optical system design results of HDI. (a) Optical structure of HDI; (b) distribution map of HDI image points in spatial dimension

Fig. 6. Local interferogram measured by HDI at maximum image separation in different dimensions. (a) Local interferogram at maximum image separation in spatial dimension; (b) local interferogram at maximum image separation in spectral dimension

Fig. 7. Restored spectrum comparison at maximum image separation in different dimensions. (a) Restored spectral curves of all spectral samping points; (b) restored spectral curves of the 60th to 450th spectral samping points; (c) linear fitting curve of the restored spectral differences among the 60th to 450th spectral samping points

Fig. 8. Radiation response of HDI to completely linear polarized light with different polarization angles. (a) Global interferogram of HDI; (b) radiation response curve of HDI to completely linear polarized light

Fig. 9. Experimental setup for HDI spectral testing in thermal vacuum environment

Fig. 10. HDI atmospheric vertical field of view and spatial resolution test experimental setup

Fig. 11. Test diagram of vertical field of view of HDI. (a) Distribution of star point array target on HDI image plane; (b) average distribution of image points in 1024 columns of detector

Fig. 12. Structure of Tianlu-1 satellite and HDI. (a) Layout of Tianlu-1 satellite; (b) internal composition of HDI

Fig. 13. Variations of orbital altitude and HDI atmospheric altitude coverage with image frame count. (a) Variation of orbital altitude with image frame count; (b) variation of top atmospheric height H₂ with image frame count; (c) variation of bottom atmospheric height H₁ with image frame count

Fig. 14. HDI Level 1 spectral data products. (a) Reconstructed spectrum of HDI on-orbit data; (b) reconstructed spectrum at typical altitude levels (2 km spatial resolution after 20 rows binning)