1. A split aperture radiation sensor having an entrance aperture of area A comprising at least two apertures separated by a distance B, a detector array comprising plural transducers arranged to receive focused radiation from said entrance aperture, relay means located between said entrance aperture and said detector array for redirecting and focusing radiation received within said entrance area A onto said detector array, wherein the improvement comprises, phase adjusting means included in said relay means for adjusting the phasing of radiation traversing said relay means from said split aperture as a function of time to produce a time varying diffraction pattern at said detector array, said time varying diffraction pattern having frequency components related to spatial frequencies of radiation incident on said split aperture.