Applications of digital speckle pattern shearing interferometry in characterization of fluids

Digital speckle pattern shearing interferometry is a robust optical technique mostly used for measuring small deformations in solid objects. In this paper we focus on applications of this technique in characterization of liquid and gaseous samples. We demonstrate this by a few examples: measurement of the density (temperature) profiles inside a candle flame and around a hot wire in air. Also, we study the diffusion process in a binary mixture and measure the diffusion coefficient. The results of these studies confirm that this highly sensitive, nondestructive, and real-time technique is ideal for investigation of fluid specimens.