Etched and formed extractor grid

摘要

An electron source comprises at least one cathode means, and at least one extractor grid which is used to extract electrons from the cathode means. The extractor grid is a substantially planar sheet having at least one aperture and also has at least one spacing member for spacing the extractor grid at a constant, predetermined spacing from the cathode. Each of the spacing members are formed by removing material around a substantial portion of the periphery of the aperture and folding the remaining portion of the periphery of the aperture at substantially a right angle to the planar sheet.