DISPLACEMENT MEASUREMENT DEVICE AND DISPLACEMENT MEASUREMENT METHOD

摘要

A displacement measurement device includes: a light source; a first diffraction grating and a second diffraction grating arranged along a path of light from the light source and movable relative to one another, the first and second diffraction gratings generating diffracted light; an optical sensor that detects interference light produced by interference between −nth order diffracted light generated as a result of the second diffraction grating diffracting +nth order diffracted light from the first diffraction grating and +nth order diffracted light generated as a result of the second diffraction grating diffracting −nth order diffracted light from the first diffraction grating, where n is a natural number greater than or equal to 1; and a calculation unit calculating, according to a signal from the optical sensor, a relative displacement between the first and second diffraction gratings in a direction orthogonal to an optical axis of the first and second diffraction gratings.

主权项

1. A displacement measurement device, comprising:
a light source; a first diffraction grating and a second diffraction grating that are arranged along a progression path of light from the light source and that are movable relative to one another, the first diffraction grating and the second diffraction grating generating diffracted light; an optical sensor that detects interference light produced by interference between −nth order diffracted light generated as a result of the second diffraction grating diffracting +nth order diffracted light from the first diffraction grating and +nth order diffracted light generated as a result of the second diffraction grating diffracting −nth order diffracted light from the first diffraction grating, where n is a natural number greater than or equal to 1; and a calculation unit that calculates, in accordance with a signal from the optical sensor, a relative displacement between the first diffraction grating and the second diffraction grating in a direction orthogonal to an optical axis of the first diffraction grating and the second diffraction grating.