| 摘要 |
An apparatus for measuring the displacement of an object includes: a diffraction grating arranged on the object, a light source for irradiating a coherence light beam onto the diffraction grating, a first detector for causing two light beams whose phases relatively shift upon linear motion of the object of diffracted light diffracted by the diffraction grating to interfere with each other to detect the interference light beam, and a second detector for causing two light beams whose phases relatively shift upon rotary motion of the object of diffracted light diffracted by the diffraction grating to interfere with each other to detect the interference light beam.
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