Patent ID: 9064678
Filing Date: 2015-06-23
Classification: H01J

Abstract:
1. A photosensor apparatus, comprising: a first housing of an optically transparent dielectric material window having a conductive layer as a photocathode for converting photons into photoelectrons; a base plate to which said first housing is attached; a through-channel centrally located on said base plate; a windowlet, within or covering said through-channel, configured for directing light from said first housing through said through-channel of said base plate; a scintillator surface on said windowlet for converting electron impacts upon said scintillator surface into secondary light transmitted through said windowlet; a first electrically conductive hermetic seal between a periphery of said first housing in electrical contact with said photocathode, and a periphery of said base plate; a second electrically conductive hermetic seal, between said windowlet and said through-channel with said base plate, which is in electrical contact with said scintillator; wherein said first housing is configured with said first and second electrically conductive hermetic seals for retaining an ultrahigh vacuum level between said optically transparent dielectric material window and said base plate; a second housing disposed on a back side of said base plate having an interior shape for focusing photoelectrons converted at said photocathode layer of said optically transparent dielectric material window upon said windowlet in response to a high voltage applied between said first and second electrically conductive hermetic seals to which electrical connections are established within said second housing; wherein said second housing is not subject to said ultrahigh vacuum level of said first housing; an optical detector retained within said second housing and having a sensing area positioned in said second housing for receiving secondary light from said windowlet; and wherein an electrostatic field formed by said first housing, said second housing and said second electrically conductive hermetic seal focuses photoelectrons from said photocathode onto said scintillator surface, which has a surface area multiple orders of magnitude smaller than that of said photocathode.