| 摘要 |
PROBLEM TO BE SOLVED: To provide an aligner in which a lens tube which holds a reduction projection lens and a reduction projection optical system can be protected against distortion, static deformation or wobbling, vibrations and the like when the reduction projection optical system is mounted on the aligner body. SOLUTION: A static pressure pad 3e as a static pressure means is provided on the undersurface of the lens barrel flange 3b of a lens barrel 3a in a reduction projection optical system 3, the reduction projection optical system 3 is mounted on a lens barrel support member 5a of an aligner body 5 through the intermediary of the static pressure pad 3e, by which the load on the projection optical system 33 can be nearly all or partially supported by the static pressure pad 3e, the influences of the surface accuracy of a lens barrel support surface and foreign objects residing between the lens barrel support surface 5c and the lens barrel flange 3b can be eliminated, the reduction projection optical system 3 can be mounted without distorting its projection lens and lens barrel, restrained from deteriorating in aberration, and enhanced in exposure accuracy.
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