| 摘要 |
PROBLEM TO BE SOLVED: To provide an aligner having demanded durability, by protecting a lens and a mirror in the illumination system of an exposing system from a deterioration like cloud or burn, which solves the problem of strong light irradiation over a long time or the lens and the mirror are put under severe circumstance with large differences in the temperature. SOLUTION: An alignment optical filter 4 is provided at the front stage of an optical path, made up of optical members like a lens or a mirror in an illumination system 23 for generating an irradiation light beam necessary for exposure and alignment. At the stoppage of exposure or during alignment, an output light beam of a mercury lamp 3 passed through the alignment optical filter 4 is irradiated to the optical system, and the output light beam of the mercury lamp 3 is irradiated directly to the optical system, only during the exposure.
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