Pyroelectric and other thermal-radiation detectors with film element(s)

摘要

An infrared detector element (20) comprises a flexible continuous film (10) of polymer material which has pyroelectric or other temperature- dependent characteristics and which is also piezoelectric so also generating microphony when it vibrates. In accordance with the invention the mounting arrangement (30,31,32) for the film (10) comprises mutually- spaced supports (32), e.g. tapered ridges (32) of a moulded- plastics substrate (30); the spacing (x) between neighboring supports (32) adjacent to the detector element (20) is sufficiently small and the tension (P) of the film (10) is sufficiently large that the natural frequency of vibration of the parts of the polymer film (10) between these neighboring supports (32) is higher than the frequency bandwidth of the detector, e.g. as determined by the highest operating frequency of a read-out circuit to which the detector element (20) is connected. This arrangement significantly reduces the effects of microphony in contributing to the electrical output of the detector. The ridge portions (32) may form a continuous network around cavities (35) below the detector elements (20 ), and a conduit may extend into each cavity (35) with that at the opposite face (12) of the polymer film (10).