A NOVEL DIGITAL MOIRE SUBTRACTION INTERFEROMETER

摘要

Optical temperature measurement techniques are particularly advantageous in that full field information is obtained. Their non-intrusive nature is particularly suited to the measurement of free convection flows, whilst the negligible mass of the photon allows an instant response time facilitating the study of very rapid transients. The application of tomographic principles has led to the development of three dimensional systems. The single greatest restriction in the application of interferometry as a standard measurement methodology has been the enormous cost associated with the optical equipment required. This cost is due to the quality of the optics required, which exhibits an exponential dependence on size. Digital Moire Subtraction is a recently developed technique which removes the restriction on the use of high quality optics. In this paper, a novel Digital Moire Subtraction interferometer configuration is presented with a 140mm field of view. The ability of the interferometer to accurately measure the free convection temperature field about an isothermal horizontal cylinder is examined through a comparison with measurements from the literature using standard interferometry. It is hoped to extend this interferometer to three dimensions by incorporating tomographic techniques.