| 摘要 |
PURPOSE:To reduce the measuring errors due to thermal expansion and contraction to the minimum value, by arranging the incident light axis of a light beam, the light axis of a collimator lens, and the axis of the rotary center of a rotary mirror on the same plane. CONSTITUTION:Fixed mirrors 14A and 14B reflect a light beam 12 from a laser tube 10, which generates the beam, and project the beam to a rotary mirror 16. The fixed mirros 14A and 14B and a collimator lens 18 are attached on a same base table 46. A base 48 of the rotary mirror 16 is arranged in such a way that the base 48 is moved with the following axes and a pin hole as centers: the incident light axis of the light beams 12 to the rotary mirror 16 through an intersection 50 between a light axis 18A of the collimator lens 18 and the reflecting surface of the rotary mirror 16 with respect to the base table 46; a pin axis, which is located on an axial line 52 that intersects with a plane including the light axis 18A of the collimator lens 18; and a pin hole 56. The incident light axis of the light beam 12, the light axis 18A of the collimator lens 18, and the central rotary axis 16A of the rotary mirror 16 are arranged on the same plane. |
