Applications of Spectral Interferometry in Sub-THz, Infrared and Optical Frequency Ranges

The paper presents some results of the noise spectral interferometry (SI) for precise distance measurements in sub-THz Infra-Red and optical bands using low-coherence optical sources beyond their coherence zone. It is shown that when the path difference in Michelson interferometer exceeds the coherence length of the light-emitting diode radiation, the pattern of interference in spectral domain enables to perform absolute measurements of micro- and nano- distances due to its dependence on both time delay and relative phase of the signals.