US: Experts have developed a new imaging device based on compressive sensing (CS) to accurately capture remote hyperspectral images. The device is called the Coded Aperture Snapshot Spectral Imager-Dual Disperser (CASSI-DD).
Compressive sensing (CS) uses fewer snapshots and measurements than traditional sensors to capture hyperspectral images. It allows the new device to capture an approximation of the full hyperspectral scene with a single snapshot. The device disperses incoming light with a prism, blocks 50% of the light with a coded aperture, and realigns the spectrum with a second prism. It uses a photodetector to measure the resulting multiplexed spatial and spectral information of the entire scene. The camera system associated with the sensing model is inverted by applying an algorithm. This is used to generate an approximate reconstruction of the hyperspectral cube using CS measurements. Additional measurements taken from different coded apertures improve the approximation. This allows faster and flexible sensing, since it produces coarse approximations of the entire scene with the first few snapshots. These approximations are used to determine whether further snapshots are needed for additional refinement. The CASSI-DD has only been demonstrated on close-up scenes with large-scale features. The device is developed by John Greer from the National Geospatial-Intelligence Agency and his team.