| 摘要 |
PROBLEM TO BE SOLVED: To prevent deformation of a base that holds a device in the internal space of a vacuum chamber. SOLUTION: When a force that would deform the base 15 acts due to evacuation of the interior space 10A, 10B of the vacuum chamber 11, the pressure difference between the interior space 10B and an external space is made to act on so as to cancel the deformation of the base 15 via a correction mechanism 50. Consequently, deformation of the vicinity of a central part of the base 15 is prevented, and it becomes possible to properly maintain the flatness of the base 15. COPYRIGHT: (C)2008,JPO&INPIT
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