| 摘要 |
PURPOSE:To adjust an optical axis accurately and easily by arranging an optical element and a space position display plate on the same holding part closely. CONSTITUTION:A reference line 13a for displaying a desired space position is provided to one surface of the space position display plate 13, and it is, for example, a cross line or a combination of concentric circles. A reflecting mirror 12 is formed by vapor-depositing a multilayered film dielectric on a glass substrate, and has, for example, a 4,579Angstrom thickness, 45 deg. angle of incidence, and about 99% reflection factor. When this multilayered film reflecting mirror is used, light such as laser light is reflected by 99%, but other kinds of light are transmitted. Therefore, the reference line 13a on the space position display plate 13 is recognized when viewed as shown by an arrow X (in a normal direction in a reflecting surface). In a figure, 15 is light on the reflecting mirror 12. |
