| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of accurately aligning the center of an opening for limiting an opening angle having an optical axis for a charged particle beam. SOLUTION: For optical-axis alignment, projection lenses are adjusted so that an image at an opening 7 for limiting an opening angle is formed on an image-forming surface 12. Of the electron rays which formed the image, the electron beam passing through a minute opening 13 is detected by a scintillator 14 and then converted into a current by a photomultiplier 15, in which the state a scan polarizer is driven to move the image at the opening 7 for limiting the opening angle formed on the image forming surface 12 in a two-dimensional x-y direction for scanning purposes. When an amount moved by the image is indicated in (x, y), the intensity of an electron ray detected by a detector in response thereto is indicated with A (x, y). The position of the optical axis for the electron beam is found from the maximum value for A (x, y), and the image at the opening 7 for limiting the opening angle is found by digitizing A (x, y) and then finding the central position thereof. In addition, a polarizer 6 is adjusted, so that both the central position thereof and the optical axis coincide.
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