Fourier-transform spectroscopy using a Michelson or other two-beam interferometer with the sample placed in one arm of the interferometer.
Note:
This method provides information about the phase change as well as the amplitude change caused by the sample.
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 656 (https://doi.org/10.1515/pac-2019-0203)