| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately find the position of a detector relative to a scale while expanding an operation temperature range even when a lens array provided to the detector is different in coefficient of linear expansion from one of a light reception part of the detector and the scale. <P>SOLUTION: A first lens array 114 and a second lens array 122 have a different coefficient of linear expansion from the scale 102 and light reception part 124, and the first lens array 114, second lens array 122, and light reception part 124 are fixed in one body at one specific place Xst of the first lens array 114 and second lens array 122. Phase signals ϕi found from a period signal Fi are each corrected so as to eliminate a phase difference due to a different coefficient α<SB POS="POST">LA</SB>, and further corrected phase signals Cϕi having been corrected are averaged to find an average phase signal ϕav, thereby finding the position of the detector 110 relative to the scale 102. <P>COPYRIGHT: (C)2012,JPO&INPIT |
