Dual-dispersive spectral linear polarization imager based on coded-aperture

Spectral and polarization detections can increase the dimension of data acquisition and enhance the capabilities of target detection systems under complicated circumstances. A spectral linear polarization imager that combines double-disperser coded aperture imaging technology with a division of focal plane polarization detector is proposed in this paper to acquire spectral and polarization information simultaneously. First, the principles and mathematical model of the system are presented, where the proposed mathematical model considers the transformations among different coordinate systems and signal transmission processes, which is realistic and provides guidance for the calibration process. Then, targeting the detection and reconstruction methods based on the Hadamard transform, the loading approach of the coded aperture and the necessity of merging micro-mirror units are analyzed. Finally, according to the actual detection demands, the proposed system can achieve measurements and reconstructions at different spectral resolutions by loading 7th- and 15th-order cyclic S-matrix templates in real-time at the coded template. The results show the Pearson correlation coefficient and the root-mean-square error between the degree of linear polarization values acquired through proposed and reference systems are 0.9975 and 0.0238, respectively. Experimental results also demonstrate that although 15th-order cyclic S-matrix template can result a higher spectral resolution compared with 7th-order cyclic S-matrix template, it decreases the accuracy of the reconstructed results, indicating a trade-off between spectral resolution and accuracy in actual detections.