| 摘要 |
PURPOSE:To easily align surfaces, to shorten the operation time, and to prevent mirror surfaces from being damaged by engaging a projections and holes provided on two surfaces crossing the mirror surfaces orthogonally with each other when mirrors are put one over the other and aligning the respective mirror surfaces with each other. CONSTITUTION:On the surface 3 crossing the mirror surfaces 2 orthogonally, three projections 5 are formed at 120 deg. intervals and three holes 6 are also formed at 120 deg. intervals shifting from them by 60 deg. The projections and holes 6 have their centers on lines connecting joint parts 8 of the mirror surfaces 2 and the center 9 of a fitting hole 4 and are at an equal distance from the center 9 of the fitting hole 4. When plural polygon mirrors 1 are put one over another by inserting a shaft into the fitting holes 4 of the polygon mirrors 1, the projections 5 formed on the polygon mirrors 1 are fitted in the holes 6 and the polygon mirrors are positioned. Namely, when many polygon mirrors are put one over another, the positions of the projections 5 and holes 6 are aligned with each other, mirror by mirror, and then six mirror surfaces 2 are automatically put in order. |
