Patent ID: 8907554

Claim:
An assembly of a support plate and an exit window foil for use in an electron beam generating device, said support plate reducing wrinkles in said foil, which wrinkles may arise due to surplus foil arising in the assembly process, said foil being bonded to the support plate along a closed bonding line bounding an area in which the support plate is provided with apertures and foil support portions and in which area the foil is adapted to serve as a portion of a wall of a vacuum tight housing of the electron beam generating device, the support plate, within said area, is provided with a pattern of apertures and foil support portions alternately, which pattern, when vacuum is created in the housing, is being adapted to form a topographical profile of the foil substantially absorbing any surplus foil, wherein the absorption is made in such a way that a substantially dominant bending of the foil occurs in said apertures, the dominant bending being made around an axis directed substantially perpendicular to the bonding line in a plane of the support plate.