Common Path Interferometry

Abstract

Common path interferometry is perhaps less common today with the availability of laser sources, but its usefulness has not been diminished. It offers many advantages in terms of ease of operation under difficult shop environments that may even preclude unequal path interferometry. Since only the classical requirements for coherence length of the light source need be met, conventional arc lamps may be used. The laser still provides a better source since the intensity is generally so much higher than can be obtained with arc lamps that short photographic exposures can be used in obtaining interferograms.