Image intensifiers and method of producing same

A method of manufacturing a shielded faceplate for use in an image intensifier having a photocathode, said method including the steps of:

• providing a mold having an inner wall defining a cavity which symmetrically surrounds a vertical axis of said mold, the diameter of said cavity being greater at the upper end of said mold than at the lower end thereof, said mold being formed of a material to which glass does not bond;
• placing an opaque glass disc into said cavity, said opaque glass disc being made of a material which absorbs light to which said photocathode is sensitive;
• placing a transparent glass disc into said cavity with its lower surface adjacent the upper surface of said opaque glass disc, said transparent glass disc being made of a material which is transparent to light to which said photocathode is sensitive;
• heating said glass discs to a temperature at which said discs become soft;
• forcing said glass discs into contact with the inner walls of said mold, said glass discs thereby forming a block having a shape conforming to the shape of said cavity, an inner region consisting of glass transparent to light to which said photocathode is sensitive and an outer region consisting of glass which is opaque to light to which said photocathode is sensitive;
• and
• removing said block from said mold.