| 摘要 |
PURPOSE:To reduce the shift of a rotary mirror from the center of rotation owing to its radial movement by engaging a mirror fitting surface and a mirror with each other by aligning their engagement contact surfaces in a high temperature state at the time of use in consideration of the coefficients of thermal expansion of the materials of the mirror fitting surface and mirror. CONSTITUTION:A mirror fixing shaft 1 is made of a SUS-based material and the rotary mirror 3 is made of an aluminum-alloy-based material, and the projecting annular part 5 of the mirror fitting surface and the recessed groove part 6 of the mirror 3 engage each other while having a clearance at room temperature. The sizes of the projecting annular part 5 and the recessed groove part 6 at the room temperature are so set that the radius r2 of the inner periphery of the annular part 5 of the mirror fitting part 4 is equal to the radius r1 of the inner periphery of the recessed groove part 6 of the mirror 3 at high temperature in the use state. Further, a material which is equal in coefficient of thermal expansion to the material of the rotary mirror 3 is used as the materials of a mirror pressing member 2 and a clamping screw 7, so the shifting of the rotary mirror 3 due to its radial movement from the center of the rotary shaft 1 can be suppressed. |
