Optical device and spectrometer

An optical device, comprising:

• a first light source configured to emit measurement light;
• a second light source configured to emit laser light having a wavelength different from that of the measurement light emitted from the first light source;
• a light splitter configured to split the measurement light into a first beam of the measurement light and a second beam of the measurement light and then mix the first beam of the measurement light and the second beam of the measurement light, and configured to split the laser light into a first laser light beam and a second laser light beam and then mix the first laser light beam and the second laser light beam;
• a first mirror configured to move with respect to the light splitter, and reflect the first beam of the measurement light and the first laser light beam, thereby adding a first modulation signal to the first beam of the measurement light and adding a displacement signal to the first laser light beam;
• a second mirror configured to reflect the second beam of the measurement light;
• a first color separator configured to separate the second beam of the measurement light from the second laser light beam based on a difference in wavelength;
• an optical modulator driven based on a drive signal and configured to add a second modulation signal to the second laser light beam after separation by the first color separator;
• a first photodetector configured to receive the measurement light including the first modulation signal and a sample-derived signal derived from a sample, and to output a first light reception signal;
• and
• a second photodetector configured to receive the laser light including the displacement signal and the second modulation signal and to output a second light reception signal.