| 摘要 |
PURPOSE:To prevent the radial dimension of a shield material from increasing by installing a photoirradiating device behind the shield material, arranging four mirrors in specific directions, and providing a target which is perpendicular to the axis of the shielding material. CONSTITUTION:A convex lens 6 is arranged having its optical axis 15 coincident with and parallel to the axis of the shielding machine and a 1st mirror 7 is in front of a convex lens 6 in the axial direction of the shielding machine 1 and slants by 45 deg. to the optical axis 15. A 2nd mirror 8 is at the focusing position of the convex lens 6 and provided perpendicular to the optical axis 15 opposite to the 1st mirror 7. A 3rd mirror 9 is provided above the 1st mirror 7 in the radial direction of the shielding machine 1 in parallel to the optical axis 15. A 4th mirror 10 is provided below the 4th mirror 10 in the radial direction of the shielding machine 1 while slanted reversely by 45 deg., and the target 11 is provided perpendicular to the optical axis 15. A light spot formed on the target 11 is picked up by a television camera 12 and rotary and horizontal movement type shutters 13 and 14 are so provided to open and close irradiation paths of laser light to the mirrors 8 and 9.
|
