CORRECTION OF CHROMATIC ABERRATION WITH AN ELECTRON-MIRROR

An experimental demonstration of correction of chromatic aberration by an electron mirror is reported. A hyperbolic electrostatic electron mirror, operating in its converging range and symmetric mode, was used as the corrector. A separating system consisting of three magnetic deflectors, two pairs of relay lenses, and an interface lens, with deflections taking place at image planes, was used to implement the mirror. The electron optical system to which the correction was applied was operated in the probe mode. The conditions for correction were investigated by means of the shadows cast by a fine mesh placed closely following, or preceding, the final image. This experimental demonstration verifies the theoretical basis for using mirrors as correctors, and also serves as a successful test of the method of separating the beams headed toward and away from the mirror.