| 摘要 |
PROBLEM TO BE SOLVED: To suppress the change of the angle of incidence of an incident luminous flux on an objective optical system even when a deflection mirror supporting member is deformed by an external stress by respectively making the surface of one side and the surface of other side of two surfaces orthogonally crossing with each other of a penta prism to be utilized as a deflection mirror the incident surface and the light-emitting surface of a laser beam. SOLUTION: A deflection prism 31 is made a penta prism and the surface of one side and the surface of other side of two surfaces orthogonally crossing with each other of the mirror 31 are respectively made an incident surface 311 and a light-emitting surface 312 and two surfaces whose crossing angles are 45 degrees are made reflection surfaces 313, 314 and the mirror 31 is fixed to the inner wall of a rotating arm. Then, a laser luminous flux 13 from a polarizing mirror is made incident on the incident plane 311 and it is reflected on the reflection surfaces 314, 313 and then it is emitted from the light-emitting surface 312 to be made incident on the floating type optical unit 6 being in the downward direction. Here, since the prism 31 is made the penta prism, even when the angle of incidence of the incident laser lumonous flux on the mirror is changed by the deformation of the rotating arm to which the prism 31 is fixed or the like, the change of the angle of incidence θ of the incident laser luminous flux on the unit 6 is suppressed. |
