| 摘要 |
PROBLEM TO BE SOLVED: To provide an absolute surface reference which makes it possible to automatically correct a shift in the position of a glass sample relative to one plane. SOLUTION: The automatic focusing system is formed by arranging a one filament 34 in the optical path between a light source 18 and an objective 24, positioning the filament 34 in the optical path so that the objective is put in focus on the surface 14 of the glass sample 12, and specifying the surface 13 on which the objective 24 is put in focus when an image of the filament appears in the visual field of the objective 24. |
