Practical common-path interferometry for real-time thermal/fluid flow measurements

Interferometric technique can be a useful gross-field diagnostic tool for quantitative and qualitative evaluation of thermal/fluid flow phenomena. Here, we present a practical interferometric approach based on a common-path configuration of the interfering beams with some results for demonstration. It incorporates advances in the modern optical technology to fully exploit the potential of interferometric techniques for on-site applications. The results of the initial testing are encouraging. The approach can allow one to build a simple and compact system insensitive to external disturbances for real-time monitoring with good measurement accuracy. The system errors contributed by low-quality optics can be eliminated by employing a moire technique. The approach based on the numerical moire, which utilizes the images directly captured by a solid-state camera to avoid wet chemical processing, appears to be promising. (C) 1998 Elsevier Science Ltd.