ELECTRON BEAM DEFLECTION CONTROL METHOD AND APPARATUS

摘要

Method and apparatus for controlling the deflection of an energy beam to impinge a workpiece with improved accuracy. A computer and interface unit direct the movement of the beam over a master target to learn and record addresses of impingement areas corresponding to those on a workpiece. Differential current flow in two conductive elements is used to determine accurate location of the address. Upon the substitution of a workpiece for the master target, impingement addresses can be selected without additional corrective deflection circuits.