Abstract: An incident radiation sensing apparatus comprises an array of photosensitive elements formed as an integrated circuit on a substrate. Each of the photosensitive elements includes a capacitor for storing charge, a conductive means for charging the capacitor to a preselected magnitude, a blocking means for inhibiting the discharge of charge stored on the capacitor; and a photoresponsive means formed from deposited semiconductor material for generating charge carriers at a rate responsive to the intensity of radiation incident upon the photoresponsive means. The photoresponsive means is connected to the capacitor so that the charge carriers generated in the photoresponsive means reduce the magnitude of the charge on the capacitor as a function of the magnitude of, and the time incidence of, the incident radiation.