Patent ID: 7687782

Claim:
A beam deflection scanner that performs changing periodically a beam trajectory of an ion beam or a charged particle beam which has a normal constant trajectory in a vacuum space, with reciprocating beam scanning by electrostatic deflection, said reciprocating beam scanning being made with varying scanning electric field of a pair of scanning electrodes, said beam deflection scanner comprising: said pair of scanning electrodes installed on the beam trajectory so as to be opposed to each other with the beam trajectory, and interposed upon said beam trajectory; and, within a zone of said scanning electric field on said beam trajectory, a pair of electric field correction electrodes which are additionally correcting the scanning electric field, said pair of electric field correction electrodes being installed in a direction perpendicular to an opposing direction of said pair of scanning electrodes interposed said zone in which said pair of scanning electrodes are installed and extending along a beam traveling axis within the substantially equal length of said zone, wherein said pair of electric field correction electrodes are installed with a central axis of a reciprocating scan plane of the ion beam or the charged particle beam interposed upon said beam trajectory, wherein positive and negative potentials are alternately applied to said pair of scanning electrodes, while some correction voltage is constantly applied to each electrode of said pair of electric field correction electrodes, wherein said pair of electric field correction electrodes each have thin rod structure, which generate narrow electric field towards a beam axis direction, and said correction electric field produced by said pair of electric field correction electrodes is especially exerted on the ion beam or charged particle beam passing between said pair of scanning electrodes at the time of switching between said positive and negative potentials.