Laser interferometer

A laser interferometer comprising:

• a laser light source configured to emit first laser light;
• an optical modulator that includes a resonator element and is configured to modulate the first laser light using the resonator element and generate second laser light including a modulation signal;
• a light receiving element configured to receive the second laser light and third laser light including a sample signal generated by an object to be measured reflecting the first laser light and output a light reception signal;
• and
• a calculation unit configured to calculate a displacement of the object to be measured from the light reception signal based on a reference signal, wherein
• the calculation unit includes
• a preprocessing unit configured to execute a preprocessing of extracting a frequency modulation component from the light reception signal and output a preprocessing signal,
• a demodulation processing unit configured to mix the preprocessing signal with orthogonal signals to obtain a mixed signal and then execute a demodulation processing of extracting the sample signal from the mixed signal, and
• an orthogonal signal generation unit configured to generate the orthogonal signals based on a phase of the reference signal and an amplitude of the preprocessing signal, or based on the phase of the reference signal and an amplitude of the mixed signal.