A theoretical performance comparison of six electrostatic e‐beam deflectors

The following electrostatic e‐beam deflectors are simulated numerically and compared: (1) Box deflector; (2) modified box deflector; (3) dokekapole deflector; (4) simplified octupole deflector; (5) 20‐pole deflector; (6) conventional octupole deflector. Two types of aberrations arise in the deflection of an electron‐image of negligible size: raster distortion and spot blurring. For each deflector, these aberrations are computed and plotted as functions of deflection amplitude. The present computations make no use of perturbational aberration theory but rely on the method of ray tracing in 3D fields. The full effect of fringe fields due to finite gap widths and finite lengths of electrodes is accounted for. The surface‐charge density method has been utilized for the accurate numerical calculation of the fields.