Abstract: The disclosure is directed to an apparatus for detecting radiation having wavelengths from about 0.4 .mu.m to about 5.6 .mu.m. An optical coating is applied to a thermal sensor that is normally transparent to radiation with such wavelengths. The optical coating is thin and light and includes a modifier and an absorber. The thermal sensor can be a pyroelectric detector such as strontium barium niobate.

Abstract: A device which includes proximately disposed electrodes in side-by-side relationship on a surface of a pyroelectric material which electrodes serve to transmit a signal. The electroded surface preferably contains the c-axis, or is parallel to it, and the performance of the detector is determined, apart from material parameters, by the parallel length of oppositely disposed electrodes and the separation therebetween. Pyroelectric detectors fabricated with essentially single surface coplanar electrodes are more economical and achieve better responsivity than electrodes disposed in opposed planes normal to the c-axis, as in conventional devices. Poling requirements of materials useful in pyroelectric detectors of this invention are similar to the requirements of materials used with conventional c-face (i.e., c-axis normal) electroded devices.