High-speed Fourier-transform spectroscopy apparatus and spectroscopy method

A spectroscopy method to be performed in a Fourier-transform spectroscopy apparatus comprising an interferometer comprising a beam splitter structured to split light emitted from a light source into reference light and scanning light, a first arm structured to reflect the reference light by a first mirror such that it is re-input to the beam splitter, and a second arm structured to reflect the scanning light by a second mirror such that it is re-input to the beam splitter, wherein the interferometer is structured to combine the reference light and the scanning light re-input to the beam splitter so as to generate an interference wave;

• and
• a spectroscopic spectrum generating unit structured to generate an interferogram based on an intensity of detection light obtained from a detection target after either light emitted from the light source or the interference wave thus combined is irradiated to the detection target, and to apply a Fourier transform to the interferogram,
• wherein the second arm is configured such that a scanning mirror is arranged on a light path of the scanning light between the beam splitter and the second mirror so as to delay or advance the scanning light with respect to the reference light according to a rotational angle of the scanning mirror,
• and wherein the spectroscopic spectrum generating unit corrects a group delay which is a delay between an envelope of the reference light and an envelope of the scanning light and a phase shift with respect to a carrier wave included in each envelope, such that the group and the phase are aligned at regular intervals.