| 摘要 |
PURPOSE:To prevent any positional or angular aberration which might accompany the deflection by placing three air-core coils in the magnetic field of an electromagnetic lens, supplying to each coil a current perpendicular to the sum of the squares of two kinds of deflection signals and making the proportional constant variable. CONSTITUTION:Electron rays produced from an electron gun 11 are deflected with deflecting coils 15X and 15Y through convergent lenses 12 and 13 and a diaphragm 14. The deflected electron rays are then deflected with an objective 18 before being irradiated upon a sample 19. Next reflected electrons are detected with a reflected-electron detector 20 before being supplied to a CRT22 through an amplifier thereby displaying a reflection electron image obtained by subjecting a specified area of the surface of a sample to angular scanning carried out with electron rays. Correction air-core coils 24-26 are coaxially placed in a magnetic field formed by the lens 18, an arithmetic circuit 27 supplies to the coils 24-26 a current perpendicular to the sum of the squares of the deflection angles of electron rays and the proportional constant is made variable. By the means mentioned above, any positional aberration and angular aberration which might accompany the deflection can be prevented. |
