Spectral imaging can obtain spectral information of target scenes and has wide applications many fields such as biomedical, military, agricultural, food safety. Coded aperture snapshot spectral imager (CASSI) proposed a snapshot spectral imaging system by employing compressed sensing theory. However, the use of the dispersion element leads to a deviation in the direction of light propagation, resulting in a complex system. This paper proposes a spectral imager that utilizes metasurface array instead of dispersion elements to encode the spectrum of the incident light and uses macro pixel segmentation method for spatial code. In terms of design, we designed nine nanofin structures with different longer and shorter axes. And these nine nanofin structures are formed as a macro pixel. Due to the fact that the design of the metasurface is not a C4 structure, it has a polarization conversion effect. When linearly polarized light is incident, the output will become two orthogonal polarized light with different spectral transmission. By utilizing the polarization image sensor on the detection end, more information can be obtained in one snapshot to increase the accuracy of recovery.
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