An optical designator system employs a remote source of electromagnetic energy, such as a small hand-held infrared LED or the like, to generate an identifying beam which is directed to the same faceplate through which a displayed image is viewed. A diffuser medium is disposed at the image plane along the rear surface of the faceplate and scatters the incident beam of electromagnetic energy toward orthogonal pairs of photodetectors located adjacent to the edges of the faceplate. The output signals from the photodetectors are presented to a normalizer circuit which compensates for intensity variations of the source of electromagnetic energy into the faceplate. Therefore, the output signal from each normalizer circuit varies in a relationship which is proportional to the distance between the photodetectors at which the incident beam strikes the diffuser medium. The remote energy source is preferably modulated with a waveform which is discernible both from background ambient light and that of the displayed image. Optical and electrical filters associated with the photodetectors insure that normalizer circuits respond only to electromagnetic energy from the remote source.