Abstract: A shutter 3 which can be momentarily held open and immediately closed, is disposed adjacent to an aperture stop 4 in an optical system, and a temperature sensor 5 is provided for measuring the temperature of the shutter 3. The blades of the shutter 3 can be utilized as a reference heat source. With the shutter 3 disposed adjacent to the aperture stop 4, the optical equivalence in the case when a reference heat source is inserted and in the other case, is not spoiled. A shutter 202 which can be readily momentarily held open and immediately closed under control of a shutter controller 203, is disposed at the optical pupil position of a combination lens 201. When the shutter 202 is closed, thermal image data is stored in a shading memory 208.

Abstract: This invention relates to an image input method and a system therefor for raster-scanning an object which makes periodical movements and for obtaining thermal images thereof. The invention comprises the steps of taking in such periodical movements of the object as trigger signals for each revolution period, controlling the scanning speed of a raster scanning mechanism in accordance with the period of such trigger signals, reading arbitrary and different partial images for each of the raster scanning by the mechanism using the trigger signals as references when synchronization is fully established, and synthesizing imagers for one frame to display thermal images on a TV monitor screen.