Electron beam recording and readout on thermoplastic film

Claim 1

A RECORDING PLAYBACK DEVICE FOR USE IN READING OUT INFORMATION STORED IN THE FORM OF SMALL DEFORMATIONS PLACED IN THE SURFACE OF A SOLID THERMOPLASTIC FILM RECORDING MEDIUM INCLUDING IN COMBINATION AN ELECTRON GUN ASSEMBLY CAPABLE OF DEFLECTING ITS ELECTRON BEAM OVER A WIDE DEFLECTION ANGLE, MEANS FOR APPLYING A READING ENERGIZING POTENTIAL TO SAID ELECTRON GUN HAVING AN ENERGY VALUE IN THE VICINITY OF THE SECOND CROSS-OVER POTENTIAL OF THE RECORDING MEDIUM, A VACUUM TIGHT HOUSING ENCLOSING SAID ELECTRON GUN AND SAID RECORDING MEDIUM FOR POSITIONING THE GUN IN CONFRONTING RELATION WITH RESPECT TO THE DEFORMATIONS IN THE SURFACE OF THE RECORDING MEDIUM, AND DIFFERENTIAL COLLECTING MEANS POSITIONED, WITHIN SAID HOUSING IN CONFRONTING RELATION WITH RESPECT TO THE RECORDING MEDIUM AND DISPOSED OUT OF THE PRIMARY ELECTRON BEAM PATH AND ON OPPOSITE SIDES OF THE SMALL DEFORMATIONS IN THE SURFACE OF THE SOLID THERMOPLASTIC FILM RECORDING MEDIUM FOR COLLECTING SECONDARY ELECTRONS EMITTED FROM THE SURFACE OF THE RECORDING MEDIUM UPON IMPINGEMENT THEREON OF THE PRIMARY READOUT ELECTRON BEAM.