Patent ID: 11885879
Assignee: MITUTOYO CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 8:
9. A measurement method comprising:
outputting a frequency-modulated laser beam with a plurality of modes from a laser apparatus having an optical cavity;
branching a first portion of the frequency-modulated laser beam as a reference light and at least some of a remaining second portion as a measurement light;
generating a beat signal by mixing the reference light and a reflected light that is reflected by radiating the measurement light onto an object to be measured;
analyzing a first signal component corresponding to a difference in a propagation distance between the reference light and the measurement light on the basis of the beat signal;
analyzing a second signal component corresponding to a cavity frequency of the optical cavity on the basis of the beat signal; and
calculating the difference in the propagation distance between the reference light and the measurement light based on analysis results of the first signal component and the second signal component.