Fourier transform imaging spectrometry using Sagnac interferometer

The technology of image plane interferometric imaging spectrometer has been the research hotpot because of its high throughput, which brings the system a high Signal to Noise Ratio (SNR) and higher spectral resolution compared to other kinds of imaging spectrometer. In order to obtain the spectral images of scene at different distance, a system of image plane interferometric imaging spectrometer based on re-imaging is presented, which consists of a front-end objective lens, a collimator, a Sagnac lateral shearing interferometer, a back-end imaging lens and a detector. A separated front-end objective lens with zoom lens or fixed focus lens is adopted to image the scene on the first imaging plane. The light from the points in the first imaging plane is then collimated to parallel light by the collimator. Then the parallel light is sheared into two beams of coherent light by the Sagnac lateral shearing interferometer. The imaging lens converge the two beams on the detector. Intensity of the converged point is detected by the detector. The imaging system and resolution of spectrum are analyzed. Besides, two push broom modes are discussed. Experimental device is set up to detect the targets of near field indoor and far field outdoor. Twenty-six reconstructed spectral images are obtained from 460nm to 620nm. The experimental results show that the proposed imaging method is effectively applied in hyperspectral imaging of targets at different distances.