Heterodyne Fourier transform spectroscopy using moving diffraction grating

New heterodyne white-light interferometry using a moving diffraction gratin g is applied to Fourier transform spectroscopy. The grating simultaneously acts as a beam splitter and a modulator, which realizes an optical frequenc y shift of incident light. which increases the sensitivity of measurement b y heterodyne modulation. The technique was experimentally confirmed, and a spectrum of weak light was measured with high stability. This technique is expected to be effective, particularly in the infrared (IR) region where de tector noise is dominant. Furthermore. reflective optical elements can be u sed for tile proposed technique. The ease of fabrication of reflective opti cal elements compared to transmission elements is significant in the IR reg ion.