| 摘要 |
PURPOSE: To utilize an energy filer as an image-forming filter, similar to a spectrometer. CONSTITUTION: This device is an (Ω-type) image-forming symmetrical filter provided with two pairs of sector magnets 1, 2, 3, 4 for an electron microscope. Secondary color aberration is corrected by arranging two pairs of sector magnets 1, 4 and 2, 3, which are separated farther. With this structure, since a coil for generating correction hexapole magnetic field can be appropriately arranged, a color error is completely eliminated. Furthermore, tertiary aperture aberration can be corrected by arranging a hexapole coil 9 insides of surfaces symmetrical as an octapole electrode. Furthermore, tertiary aberration is corrected by directly arranging a correcting coil 5 for octapole magnetic field in an inlet of the first sector magnet 1 and directly arranging a correcting coil 13 for octapole magnetic field in an outlet of the fourth sector magnet 4.
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