| 摘要 |
PURPOSE:To vary the angle at which electron rays are irradiated upon a sample by installing a movable diaphragm between a final stage focusing lens and focusing lens which is installed in front of the final stage focusing lens and by correcting the excitation of said final stage focusing lens with that of said focusing lens. CONSTITUTION:A movable diaphragm 13 is installed in an arbitrary position located between a second stage focusing lens 11 and a final stage focusing lens 5. The degree of the excitation of the second stage focusing lens 11 can be varied so that the actual image of point (P) is imaged upon an arbitrary position located between points (Q1) and (On) which are in the back of the lens 11 and on the optical axis. The final stage focusing lens 5 diffracts electron rays 6 the orbits of which are altered by the excitational change of the second stage focusing lens 11. The thus diffracted electron rays 6 are then imaged upon the focus of a front objective 2 by the effect of the front objective 2 which is a part of an objective 1. Accordingly it is possible to vary and control the angle at which electron rays are irradiated while maintaining the focus of an electron probe to be located on a sample 7. |
