There are two distinct strains of infrared imagers, sometimes referred to as the 'staring' and 'scanning' versions. In a staring imager each element of the picture in the image plane is associated in a one-to-one fashion, either with its own detector or with its own place on a vidicon receiving screen. In a scanning imager the number of detectors is much less than the number of pixels, so the picture has to be scanned optomechanically over the detectors and their outputs electronically processed to give an acceptable picture. As of the date of this article, it is not possible to make two-dimensional arrays of detecting elements plus processing electronics with enough elements to give a high resolution picture, and even if one could one would have severe problems in ensuring detector element uniformity, so the main type of staring imager is the vidicon and in particular the pyroelectric vidicon. The article continues to describe various uses for this technology.