| 摘要 |
PURPOSE:To easily regulate a lens distortion by providing a reduction projection lens and a reticle stage with a position regulating mechanism, a contraction projecting lens and a reticle stage with a position measuring device, and a control unit for issuing a control command to the position regulating mechanism. CONSTITUTION:Signals of photodetectors 6-9 are input to an interferometer counter 31, which monitors the postions of a reticle stage 15 and a lens supporting stand 17, the outputs of which are input to a control unit 32. When a lens distortion is desirably altered, a signal is fed from the unit 32 to servo motors 27-30 to move the stage 15 and the stand 17. This displaced amount is measured by the photodetectors 6-9 and the counter 31. If it is different to a target value, the unit 32 feeds a signal to the motors 27-30 to again move the stage 15 or the stand 17. At this time, the displaced distance to be set corresponds to the variation of the lens distortion. Thus, the lens distortion can be easily and accurately regulated.
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