Abstract: The present invention involves a method for simultaneously applying an activation layer on the photoemissive layers of a plurality of photocathodes such as those used in image intensifier devices. The method includes the steps of diffusing a flux of activating chemicals over the plurality of photocathodes, wherein the flux is substantially spatially uniform with respect to the plurality of photocathodes; monitoring the sum photoresponse of the plurality of photocathodes; and terminating the flux of activating chemicals when a desired sum photoresponse is attained.

Abstract: The present invention involves a method for simultaneously applying an activation layer on the photoemissive layers of a plurality of photocathodes such as those used in image intensifier devices. The method includes the steps of diffusing a flux of activating chemicals over the plurality of photocathodes, wherein the flux is substantially spatially uniform with respect to the plurality of photocathodes; monitoring the sum photoresponse of the plurality of photocathodes; and terminating the flux of activating chemicals when a desired sum photoresponse is attained.

Abstract: A method of cleaning semiconductor wafers by use of a heat source external to the system is disclosed. The semiconductor wafers are disposed within a vacuum chamber having a transmissive window, and a radiant heat source external to the chamber is applied so that the radiation passes through the window onto the semiconductor wafers. The invention has particular application to semiconductor wafers used for photocathodes and image intensifier tubes.

Abstract: A low temperature apparatus and process exists for cleaning photo-cathodes used A lo VW pV:image intensifier tubes. The process comprises the steps of applying atomic or molecular particles of a plasma to a photo-cathode for the purpose of removing contaminants, such as oxides, from the photo-cathode surface; and applying heat or ultra-violet radiation to the photo-cathode to remove remaining impurities. The apparatus comprises means for subjecting a photo-cathode to the atomic and molecular particle products of a plasma, and preferably, means for applying heat or ultra-violet radiation to the photo-cathode at a low temperature to remove any remaining impurities from the photo-cathode.

Abstract: A method for optimizing the photo-response of a photocathode having a gallium-arsenide layer and a cesium-oxide surface coating includes the steps of overcesiating the photocathode, sealing it in a vacuum tube and baking the assembly in an oven. The photo-response of the photocathode is measured while it is baked, such measurements comprising an input to a microprocessor which controls the baking process by varying the temperature and/or time of baking. The rate of increase of photo-response due to heating and optimizing the photo-response attributable to the cesium-oxide coating is determined by utilizing a formula which relates temperature and photo-response and permits room temperature photo-response to be projected from a measurement taken during the baking process. When the rate of increase shows a characteristic diminishing pattern, the photo-response has been maximized and the baking is terminated.

Abstract: An arrangement for introducing an auxiliary gaseous medium into the interior of an exhaust tube that is joined to a downstream end of a substrate tube from which a primary gaseous medium carrying glass soot particles during a chemical vapor deposition phase of an optical preform fabrication process emerges into the exhaust tube comprises a gas injection tube which is partly received in the exhaust tube with radial spacing therefrom except at a contact zone and having a free end disposed at the region of joinder of the exhaust tube with the substrate tube. The auxiliary gaseous medium flows through the gas injection tube into the joinder region for mixing thereat with the emerging flow of the primary gaseous medium. Relative circumferential movement is effected between the contact zone and at least the exhaust tube to release any soot present at the contact zone for entrainment in the mixed flow through the spacing and out of the exhaust tube.