Patent ID: 11879975
Assignee: MITUTOYO CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 8:
9. A measurement apparatus comprising:
a laser that outputs a frequency-modulated laser beam;
a splitter that splits the frequency-modulated laser beam output by the laser such that a portion of the frequency-modulated laser beam is a reference light and at least some of the remaining portion of the frequency-modulated laser beam is a measurement light;
a beat signal generator that generates 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;
a frequency analyzer that performs a frequency analysis on the beat signal;
a non-transitory memory that stores a reference frequency signal, which is a reference signal output by the beat signal generator in a state without the object to be measured and converted into a frequency signal; and
calculation circuitry configured to calculate a difference between propagation distances of the reference light and the measurement light based on a result of the frequency analysis performed on the beat signal by the frequency analyzer, wherein
the frequency analyzer subtracts a signal level of the reference frequency signal from a signal level of a frequency signal converted from the beat signal, for each frequency, and then specifies a frequency of the beat signal.