LOW-TEMPERATURE SHIELD FOR INFRARED DETECTOR

摘要

PURPOSE: To enhance low temp. shield efficiency regardless of the quality of an injection iris necessarily lowered by the asymmetry of an optical system by housing an infrared responsive sensor element in a low temp. shield structure having an opening aligned with the sensor element. CONSTITUTION: The opening iris 13 looked from a detection element 11 prescribes an angleΩAS and a low temp. shield opening 15 prescribes an angleΩCS. The ratioΩAS/ΩCS of these angles is a measure of low temp. shield efficiency and markedly smaller than 50% representatively. By providing an injection iris formed into the shape almost coinciding with the opening iris image of an injection iris point, stray radiation can be controlled and the injection iris is demarcated by either one of the low temp. shield opening 15 itself and the separate iris member arranged just inside a low temp. shield. This injection iris functions in a mode of a Rio iris.