An infrared, IR, imaging system for imaging an object, the imaging system comprising: an optical system including an optical focal plane array, FPA, unit, the optical system including at least two optical channels, said at least two optical channels being spatially and spectrally different from one another, each of the at least two optical channels positioned to transfer IR radiation incident on the optical system towards the optical FPA unit, the optical FPA unit comprising at least two detector arrays (1, 9) disposed at a distance from two corresponding focusing lenses; a first temperature-controlled reference imaged by the at least two detector arrays (1, 9); a second temperature-controlled reference imaged by the at least two detector arrays (1, 9), wherein the first temperature-controlled reference and the second temperature-controlled reference are disposed in the same plane as the focusing lenses; first and second reflecting elements (975a, 975b) to reflect radiation from the first and second temperature-controlled references (972a, 972b), respectively, onto the detector arrays (1, 9); and a data-processing unit configured to: acquire a plurality of image frames with the at least two detector arrays (1, 9) the plurality of image frames containing regions that correspond to an image of the first and second references (972a, 972b) captured in parallel with the object; and dynamically calibrate the at least two detector arrays (1, 9) to address a difference in a temperature estimate of the first and second references (972a, 972b) between the two detector arrays (1, 9). an optical system including an optical focal plane array, FPA, unit, the optical system including at least two optical channels, said at least two optical channels being spatially and spectrally different from one another, each of the at least two optical channels positioned to transfer IR radiation incident on the optical system towards the optical FPA unit, the optical FPA unit comprising at least two detector arrays (1, 9) disposed at a distance from two corresponding focusing lenses; a first temperature-controlled reference imaged by the at least two detector arrays (1, 9); a second temperature-controlled reference imaged by the at least two detector arrays (1, 9), wherein the first temperature-controlled reference and the second temperature-controlled reference are disposed in the same plane as the focusing lenses; first and second reflecting elements (975a, 975b) to reflect radiation from the first and second temperature-controlled references (972a, 972b), respectively, onto the detector arrays (1, 9); and a data-processing unit configured to: acquire a plurality of image frames with the at least two detector arrays (1, 9) the plurality of image frames containing regions that correspond to an image of the first and second references (972a, 972b) captured in parallel with the object; and dynamically calibrate the at least two detector arrays (1, 9) to address a difference in a temperature estimate of the first and second references (972a, 972b) between the two detector arrays (1, 9). acquire a plurality of image frames with the at least two detector arrays (1, 9) the plurality of image frames containing regions that correspond to an image of the first and second references (972a, 972b) captured in parallel with the object; and dynamically calibrate the at least two detector arrays (1, 9) to address a difference in a temperature estimate of the first and second references (972a, 972b) between the two detector arrays (1, 9).