| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a displacement measurement device capable of suppressing a detection range from becoming narrow and suppressing light utilization efficiency from being decreased and to provide a displacement measurement method.SOLUTION: A displacement measurement device 100 includes a light source 12, a collimator lens 14, a pair of diffraction gratings 20, and a PD 31 being an optical sensor unit. The pair of diffraction gratings 20 comprise a first transmission type diffraction grating 21 and a second transmission type diffraction grating 22. The periodical change of the light-receiving amount of interference light 27 generated by the pair of diffraction gratings 20, corresponding to the relative movement in the x-direction of the pair of diffraction gratings 20 is detected by the PD 31. The attenuation of the interference light caused by the relative movement in the z-direction of the pair of diffraction gratings 20 does not occur, so that the detection range is suppressed from becoming narrow. Further, the pair of transmission type diffraction gratings 20 are used so that the light utilization efficiency can be suppressed from being decreased.</p> |
