Development of an Electronic Speckle Pattern Interferometer for Measurement of Concentration Gradients in a Binary Mixture

This paper describes the construction and performance of an Electronic Speckle Pattern Interferometer (ESPI) developed for measurements of concentration gradients in a binary mixture. The system uses a Mach-Zehnder interferometer with a commercially available CCD camera for image acquisition. A phase-shifting algorithm is employed to give full field measurements. The theoretical background to the optical process involved in these methods is also presented, with emphasis on using the system for analysing concentration gradients. Problems pertaining to the unknown Gladstone-Dale constants of a binary mixture are also discussed.