 Interferometers are widely used in science and industry for the measurement of small displacements , refractive index changes and surface irregularities . In analytical science , interferometers are used in continuous wave Fourier transform spectroscopy to analyze light containing features of absorption or emission associated with a substance or mixture . An astronomical interferometer consists of two or more separate telescopes that combine their signals , offering a resolution equivalent to that of a telescope of diameter equal to the largest separation between its individual elements . 
