| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical interferometric length measurement apparatus that can measure an absolute position of a moving body in a short time upon initialization of a positioning device, and that can stably measure a travel of the moving body over a long period of time. <P>SOLUTION: An optical interferometric length measurement apparatus for measuring a travel of a moving body, i.e. a slider 10, splits light into a measuring beam and a reference beam, so as to allow the measuring beam to be reflected by a measurement mirror 9 provided on the slider 10 and the reference beam to be reflected by a reference mirror 8. A refractive index along a measuring beam path reflected from the measurement mirror 9 is changed by increasing and decreasing atmospheric pressure inside a chamber 2. An absolute position of the slider 10 is measured based on a change in measured value of an interferometer due to a change in the refractive index. <P>COPYRIGHT: (C)2012,JPO&INPIT |
