Simple technique for identifying photoelastic zero-order fringe

Abstract

In most optical techniques for experimental stress analysis (for example, photoelasticity) to identify the fringe order, one usually has to identify the zero-order fringe first. Generally, a photoelastician would use a white light source to distinguish the dark fringe (zero order) from the colored ones (higher order) with the background set in the dark field. This would pose a problem if the light source is monochromatic because all the fringes obtained would appear dark. This problem is further compounded if the object is complex. Hence, it is advantageous to have a simple technique for identifying the zero-order fringe. Such a technique which makes use of an image processing system is described in this paper.