Abstract: A thermal imaging system (100) for a vehicle includes an objective lens (104) for receiving an image of the object, an eyepiece lens (102) for viewing the image of the object, and a compensator lens (106) movably located between the objective and eyepiece lenses (104, 102) for providing a thermal image of the object. The system (100) includes a servo motor control system (107, 109, 110, 112 and 114) for controlling the position of the compensator lens (106) based upon temperature, range and field of view to provide an accurate thermal image of the object.

Abstract: An infrared imaging system (10) has a detector assembly (12) positioned for viewing infrared radiation from a subject (20), and a housing (18) enclosing the detector assembly for maintaining the detector assembly at a temperature lower than a temperature of an environment outside the housing, the housing having a window (42) for transmission of radiation from the subject to the detector assembly. A cold stop (46) is located within the housing and a warm stop (48) is located outside the housing for transmitting radiation via their respective apertures (50, 52) from the subject to the detector assembly. The warm stop has a planar retroreflective surface (62) for reflecting rays from the detector assembly back to the detector assembly, thereby to minimize thermal noise.