The invention relates to a system for detection and infrared imaging by spectral analysis in several wavelength bands comprising: —an imaging sensor comprising a plurality of elementary sensors together forming a matrix sensitive surface; —an imaging optic adapted for forming on the sensitive surface of the imaging sensor, a first image of the scene to be analysed in a first wavelength band, and at least one second image of the scene to be analysed in a second wavelength band, characterized in that said detection and imaging system furthermore comprises an optical device consisting of a fixed optical plate adapted for shifting the first image with respect to the second image in the plane of the sensitive surface, the shift between the images being along a direction defined by a row, a column or a diagonal of elementary sensors, the shift distance being equal to the spacing of the elementary sensors of the matrix sensitive surface along this direction or to a multiple of this spacing.