| 摘要 |
PURPOSE:To prevent an optical attenuation member from being dirtied at the time of non-using of the member and to make it easy to set up the member on a mounting part by forming a protection cover movable to cover the optical attenuation member. CONSTITUTION:When the optical attenuation plate 1 is inserted into an insertion groove 20a of the mounting part 2, the lower edge of the protection cover 12 of the optical attenuation plate 1 is abutted upon an engaging part 20b to be a stopper for the groove 20a, the cover 12 is slided and moved upward, and under the status that a wedge part on the head of a holder 11 is engaged with the bottom surface of a case, the cover 12 is separated from the position of the optical attenuation member 10 to expose the member 10 and display a optical attenuation function. To take out the plate 1 from the mounting part 2, the cover 12 is moved downward by a restoration spring 13, and under the status that the plate 10 is drawn out, the cover 12 is restored to the position covering the member 10. Thereby, the member 10 can be always covered with the cover 12 when the plate 1 is not inserted into the mounting part 12. Conse quently, the optional attenuation member 10 can be prevented from the adhesion of dust or the like at the time of storage or the like. |
