Research on Space Spectral Imaging System Technology Based on Grating Primary Mirror

In order to improve the space emergency rescue capability at night, a new electro-optical remote sensing with computational imaging under low light conditions is designed. The hyperspectral remote sensing snapshot imaging technology was studied under the conditions of low illumination at night with the spectral resolution 5 nm. We use a long thin grating primary mirror with an optical aperture of rectangle to collect energy. The grating primary mirror can be folded in one direction during emission and unfolded in orbit. Spectral dispersion adopts snapshot spectral imaging, which uses the coding plate to encode in the primary image position, and divides the spectral data cube into 2D space for imaging for improving the system’s light energy utilization rate. At the same time, a large-dynamic range ultra-low noise ultra-high gain SPAD device is used for low-light level detection, then the target under the condition of extremely low image signal-to-noise ratio is identified stably. In order to enhance the recognition ability under low SNR 12 dB, the system adopts semantic recognition mode. We set up an experimental spectrograph and the experimental results are compared with predictions from theory. The hyperspectral computational imaging technology was studied under the conditions of low signal-to-noise ratio.