Abstract: In this sensitive, relatively inexpensive to manufacture, photo-detector, one surface of an amorphous silicon photovoltaic element is bonded to a thin transparent conductive layer formed on an insulating base. A conductive pattern is formed on the opposite surface of the element. The conductive layer may be formed of indium-tin oxide (ITO) and the photovoltaic element may be an element with an intrinsic semiconducting layer between p and n doped layers. The photovoltaic element generates component currents in response to photons passing through the transparent base and conducting layer. Those current components flowing predominantly in a direction at right angles to the photovoltaic element surfaces are summed by the conductive pattern which acts as a spatial filter, responsive to desired ones of these components and relatively unresponsive to other current components.