| 摘要 |
An aperture member (15) is configured to be mounted to a receiving portion (22) provided to a main body (2), and includes a lower surface portion (15a) formed into an arc shape. The receiving portion (22) of the main body (2) includes a bottom surface portion (22a) formed into a shape corresponding to the arc shape of the lower surface portion (15a) of the aperture member (15) so as to be brought into contact with the lower surface portion (15a) of the aperture member (15). The aperture member (15) includes a light passage opening (15e) formed so that a center position (15ea) thereof substantially matches with a position of a center of curvature of the arc shape of the lower surface portion (15a). |
