Modified Electrostatic Box Deflector for E-Beam Deflection
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
Electrostatic deflectors which are simplest to manufacture are deflec- tors using a box design. However, such deflectors cause relatively large electron-optical aberrations. A deflector is described herein which is simple to manufacture as the box deflector but produces aberrations which are an order of magnitude smaller in size, at the expense of increased electronic requirements. Fig. 1 shows an electrostatic deflector in pre-deflection mode. Let P be a point on the optical axis where a (perfect) crossover of the electron beam is located. The electrons are deflected in the transverse electric field produced by the deflector. The exit-side asymptotes of the deflected bundle of rays nearly intersect in a common point P1 in the object plane. P1 is a deflected virtual image of P.