 Interferometry is a family of techniques in which waves , usually electromagnetic , are superimposed in order to extract information about the waves . Interferometry is an important investigative technique in the fields of astronomy , fiber optics , engineering metrology , optical metrology , oceanography , seismology , spectroscopy ( and its applications to chemistry ) , quantum mechanics , nuclear and particle physics , plasma physics , remote sensing , biomolecular interactions , surface profiling , microfluidics , mechanical stress / strain measurement , velocimetry , and optometry . 
