Abstract: A device for simultaneously detecting and reflecting electromagnetic radiation consisting of a thin layer of insulating pyro-electric and/or piezoelectric material sandwiched between two conducting electrodes. The upper-most electrode is effective to separate the radiation into a reflected part and an unreflected part, which is absorbed, and the insulating layer has an electrical property dependent on the intensity of electromagnetic radiation absorbed by the upper-most electrode. An electrical voltage and/or current measured between the two electrodes is responsive to the electrical property of the insulating layer and is indicative of the intensity of the absorbed electromagnetic radiation.