| 摘要 |
PURPOSE:To control an exciting current for an object lens so as to focus a smaple always at its prescribed position, by obtaining a current fully larger than the exciting current for forming a prescribed focal length, gradually decreasing said current and obtaining the prescribed exciting current. CONSTITUTION:An electron emitted from a filament 1 is irradiated to a sample 11, and a secondary electron generated from the sample 11 is detected by a secondary electron detector 10. X-ray 12, after passing a collimator 14, is detected by an X-ray detector 13. An exciting current for an object lens 7 is controlled in such a manner that the sample is focused in a position with a certain take-out angle of X-rays obtainable. At this time, the object exciting current is controlled by also considering hysteresis characteristics of a magnetic circuit for the object lens, always decreasing the current gradually from an overfocusing state finally focusing the sample at a prescribed position for the analyzed sample. |
