An infrared (IR) imaging system is presented. The system includes a cooling chamber associated with a cooler generating a certain temperature condition inside the chamber. The cooling chamber has an optical window, and includes thereinside an IR detection unit including one or more detectors thermally coupled to the cooler and at least two cold shields thermally coupled to the cooler and carrying at least two imaging optical assemblies. The at least two imaging optical assemblies are enclosed by the cold shields in between the detection unit and the optical window and thereby define at least two different optical channels for imaging light from the optical window onto the one or more detectors of the detection unit.