Electron lens spherical aberration correcting device comprising a current carrying wire section on the lens axis

Claim 1

A SPHERICAL ABERRATION CORRECTING DEVICE FOR AN ELECTRON LENS SYSTEM WHICH IS ASSOCIATED WITH AN ELECTRON GUN FROM WHICH ELECTRONS ISSUE IN A BEAM ALONG A CENTRAL AXIS WHICH IS THE SAME AS THE LENS SYSTEM AXIS, COMPRISING SUPPORT MEANS FOR COAXIALLY SECURING SAID DEVICE TO A MAGNETIC LENS ELEMENT OF SAID ELECTRON LENS SYSTEM AT THE SIDE OF SAID MAGNETIC LENS WHICH IS OPPOSITE TO SAID ELECTRON GUN, TWO CONDUCTING HOLLOW MEMBERS COAXIALLY MOUNTED ON SAID SUPPORT MEANS IN SLIDABLE MOUNTING RELATION TO EACH OTHER, A CONDUCTING WIRE SECTION COAXIALLY SUPPORTED BY SAID CONDUCTING HOLLOW MEMBERS IN ALIGNMENT WITH THE CENTRAL AXIS OF THE LENS SYSTEM AND ENERGIZING MEANS FOR APPLYING FROM SAID MEMBERS TO SAID WIRE SECTION AN ADJUSTABLE DIRECT CURRENT IN THE DIRECTION OPPOSITE TO THE ELECTRON DISPLACEMENT, WHEREBY THE ELECTRONS ISSUED FROM SAID ELECTRON GUN UNDERGO A RADIALLY ATTRACTIVE FORCE DUE TO THE MAGNETIC FIELD PRODUCED BY SAID DIRECT CURRENT IN SAID WIRE SECTION, SAID FORCE BEING GREATER IN THE PROPORTION AS THE ELECTRONS ARE NEARER THE WIRE SECTION, AND THE DISTANCE BETWEEN THE CONDUCTING HOLLOW MEMBERS CAN BE ADJUSTED TO MAINTAIN THE WIRE SECTION ALIGNED WITH SAID CENTRAL AXIS REGARDLESS OF THE WIRE SECTION EXPANSION DUE TO THE CURRENT FLOWING THERETHROUGH.