| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce production cost and installation space without using volume adjusting bellows. SOLUTION: A mounting pipe 44 is formed on a guiding pipe 41 for the first reflection mirror unit 32. A supporting plate 46 is attached to this mounting pipe 44 with a bolt. An air filter 49 is held between this supporting plate 46 and the engaging flange 47b of a baffle 47, with a nut 48 screwed onto the threaded cylinder 47a at the tip end of the baffle 47, so that the air filter 49 is tightened and fixed. Then, the clean air is taken in through the air filter 49 by the expanding action of the first optical axis bellows 33, removing dust sticking to the outer circumferential face of the air filter 49 by the contracting action.</p> |
