Fourier transform-type spectroscopic device

A Fourier transform-type spectroscopic device comprising:

• an interferometer that includes a beam splitter which is configured to split light emitted from a light source into reference light and scanning light, a first arm which is configured to cause the reference light to be reflected on a first mirror and incident again on the beam splitter, and a second arm which is configured to cause the scanning light to be reflected on a second mirror and incident again on the beam splitter, the interferometer being configured to combine the reference light and the scanning light incident again on the beam splitter, to produce an interference wave;
• a photodetector that is configured to detect intensity of a plurality of beams of light, emitted from a sample that is repeatedly irradiated with the interference wave;
• and
• a computing device that is connected to the photodetector and is configured to produce an interferogram based on the intensity of the plurality of beams of light, and perform a Fourier transform of the interferogram,
• wherein the second arm includes a scanning mirror disposed on a light path of the scanning light between the beam splitter and the second mirror, and is configured to delay or advance the scanning light with respect to the reference light in accordance with a rotation angle of the scanning mirror from an initial position.