Abstract: An imaging system is provided which comprises an objective lens arrangement, a linear array of detector elements within a detector the array comprising a row of time delay an integrate (TDI) channels and a scanning optic arranged to scan an image over the array detector elements, the system further comprises means for rotating the scanning optic about an axis (N) normal to an optical surface of the scan optic when the scan optic is in the center of its field of view position, the scan optic being rotated about this axis (N) in dependence on the rate at which the imaging system is panned across a scene, such that a received image is vector scanned across the linear array of detector elements to compensate for loss in image resolution due to the panning action of the imaging system occurring during the period in which an image frame is detected.

Abstract: A thermal imager referencing system comprises two rotating cranks in the form of discs (7, 8) each pivotally attached to connecting member (9). The discs (7, 8) are rotated at a constant speed causing two mirrors laterally displaced along connecting member (9) to intercept an optical path X of a thermal imager associated with the referencing system. Each rotation through 360 degrees of the discs (7, 8) causes each mirror to pass once through the optical path, the mirror surfaces being respectively arranged to cause a linear array of detector elements (not shown) of the thermal imager to view alternately thermo-electric devices (14, 16), which are at different temperatures, during the flyback time associated with the thermal imager. The referencing system enables processing means of the thermal imager to normalize the detector array, compensating for DC offset and differences in gain between different elements of the detector array.