ELECTRON BEAM SOURCE, ELECTRON OPTICAL APPARATUS USING SUCH BEAM SOURCE, AND METHOD OF OPERATING ELECTRO BEAM SOURCE

摘要

PROBLEM TO BE SOLVED: To provide an electron beam source of which adjusting performance is improved so as to obtain desired electron beam intensity, and which operates at low source surface temperatures. SOLUTION: This electron beam source 1 is provided with a source surface illuminated with a photon beam 29 of adjustable intensity. The photon beam assists emission of electrons from the source surface due to a photo effect. Emission of electrons is further assisted by an electric extraction field. Furthermore, a heater is provided to further assist emission of electrons by a thermionic effect. An electron beam current is measured, and the intensity of the photon beam is adjusted based on the measured electron beam current. COPYRIGHT: (C)2004,JPO&NCIPI