| 摘要 |
PROBLEM TO BE SOLVED: To make maintainable the demension from a reference surface to a measurement surface size and parallelism or inclination between the reference surface and measurement surface through automatic control by controlling the driving element of a driving part and maintaining constant the dimension and parallelism between the reference surface and measurement surface. SOLUTION: A reference apparatus for difference in level 10 has a base 1 which forms a reference surface 1a. A columnar structural body 2 with the interior of a vacuum sealed space is fixed to the base 1. The structural body 2 is constituted to include a cylindrical body part 25, an end surface part 16 having a measurement surface 16a, and driving elements 17 set between the parts as a driving part for moving the end surface part 16. When piezoelectric elements 17 are driven, the distance between a first reflecting mirror 13 fixed to the base 1 and a second reflecting mirror 15 fixed to the end surface member 16 change, and the change of the distance changes an interference output of a laser interferometric distance-measuring meter. An interference light passing a transparent window 18 and a polarizing plate 19 is received by an interference light-receiving part 21.
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