| 摘要 |
PURPOSE: A displacement sensor is provided to enhance detection precision since interference light is not overlapped with faint light by multi reflection of each part since when light from a light source is diffracted by a diffraction grating twice, incident angles and exit angles are different. CONSTITUTION: A displacement sensor(1) comprises a diffraction grating, a grating interferometer(4), and a relative position information output unit. The diffraction grating diffracts light and is flat. The grating interferometer radiates light to the diffraction grating and diffracts the radiated light to two light beams with positive and negative orders, respectively. The grating interferometer makes the diffracted two light beams interfere each other to generate interferential signals. The relative position information output unit detects the relative position information of the diffraction gratring from the interferential signal generated by the grating interferometer.
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