Laser interference type displacement meter and displacement measurement method

摘要

PROBLEM TO BE SOLVED: To provide a laser interference type displacement meter or the like capable of eliminating a trade-off between displacement accuracy and displacement dynamic range. A laser interference type displacement meter drives a light source unit that outputs continuous light, a branching unit that branches continuous light into reference light and probe light, a modulation unit that phase-modulates reference light, and a modulation unit. A signal generator that generates a modulated signal, and a signal setting unit that sets the total amplitude of the modulated signal to a value larger than π-radian and less than 2π-radian plus 2πm (m is an integer of 0 or more) radian. It includes a light receiving unit that receives interference light between the probe light reflected by the measurement target and the phase-modulated reference light, and a calculation unit that obtains the displacement of the measurement target based on the interference signal from the light receiving unit. [Selection diagram] Fig. 1