Sub-micron pattern delineation, importantly in the fabrication of large scale integrated devices, is based on a patterned photocathode. Functionally, the photocathode plays the role of the mask in competing systems, either in proximity printing or in projection. In operation, the photocathode is illuminated by ultraviolet radiation to release electrons which are brought to focus on a resist-coated wafer with assistance of a uniform magnetic field together with an accelerating applied voltage.