Optical viewing system for electron beam welders

Claim 1

IN WELDING APPARATUS EMPLOYING AN ELECTRON BEAM GUN, THE COMBINATION WITH A VACUUM CHAMBER WITHIN WHICH SAID GUN IS MOUNTED FOR ADJUSTABLE MOVEMENT IN VERTICAL AND HORIZONTAL DIRECTIONS, SAID VACUUM CHAMBER HAVING A PIVOTED FRONT DOOR AND WHICH IS PROVIDED WITH A GLASS WINDOW, MEANS ALSO LOCATED WITHIN THE VACUUM CHAMBER FOR SUPPORTING WORKPIECES FOR MOVEMENT HORIZONTALLY AND IN A DIRECTION PARALLEL TO THE SEAM AS FORMED BY THE WORKPIECES AND WHICH SEAM IS TO BE WELDED, OF AN OPTICAL SYSTEM FOR VIEWING THE WORKPIECES AND THUS THE SEAM FROM OUTSIDE THE VACUUM CHAMBER, SAID OPTICAL SYSTEM INCLUDING A MIRROR CARRIER BY THE GUN AND MOUNTED THEREON AT AN ANGLE OF APPROXIMATELY FORTYFIVE DEGREES, SAID MIRROR HAVING AN APERTURE THEREIN WHEREBY TO PERMIT THE PASSAGE OF THE ELECTRON BEAM PROJECTED BY THE GUN DURING THE WELDING OPERATION, AND SAID OPTICAL SYSTEM ALSO INCLUDING A VIEWING DEVICE MOUNTED EXTERIORLY ON THE VACUUM CHAMBER AND HAVING SUCH ASSOCIATION WITH THE VACUUM CHAMBER AND WITH THE DOOR THAT THE SEAM CAN BE VIEWED BEFORE THE WELDING OPERATION WITH THE DOOR OPEN AND CAN ALSO BE VIEWED THROUGH THE WINDOW DURING AND FOLLOWING THE WELDING OPERATION WITH THE DOOR CLOSED.