Contoured support grid for hermetically sealed thin film applications

A process for manufacturing a support plate for an exit window having a foil transmissive layer, comprising

• providing a support grid of a first material having a first coefficient of thermal expansion;
• providing a layer of transmissive material the layer having a length, a width and an initial surface area, covering the support grid to form a seal over the grid, the layer of transmissive material having a second different coefficient of thermal expansion,
• determining as a function of at least the first and second coefficients of thermal expansion, an expanded surface area represented of a surface area of the transmissive layer after a thermal expansion;
• and
• forming a contour Is the support grid to provide the support grid with a surface area on its upper surface comparable to the expanded surface area.