ANALYTICAL APPARATUS USING CHARGED PARTICLE RAY

摘要

PURPOSE:To remove a bad influence of residual magnetism of electromagnet for mass analysis at the time of using an electron beam and to improve the incident efficiency for an optical system of the electron beam, by shielding the residual magnetism of the electromagnet at the time of irradiating the electron beam. CONSTITUTION:A magnetic shielding cylinder 8 is descended and is inserted between magnetic poles of a electromagnet 5 and an electron beam 9 is shielded from the outside magnetism and residual magnetism of the electromagnet 5 by an outside magnetism shielding cylinder 12 and the cylinder 8 and is irradiated on a sample 4. Hereby, a magnetic field in the cylinder is made to nearly perfect zero and the weak magnetic field appearings on the opening end of the cylinder is made to the symmetrical rotation with respect to an axis A and it is prevented to turn away the electron beam from the axis A.