Colorimetry in spectral interference: Investigation into the use of digitised images in photoelastic analysis

The objective of this thesis was to examine the feasibility of interpreting the colour information from a digitised image of photoelastic fringes as means of calculating and recording principal strain differences.

Each isochromatic fringe indicates a region of constant principal strain difference. When a white light source is used, the fringe colours progress through the visible spectrum as the principal strain difference increases, each is assigned a fringe order, N, such that full-order (integer, n) fringes are identified by the recurrence of a particular hue. The fractional fringe order, f, is the non-integer part of the fringe order such that $N=n+f.$ Visual identification of full and fractional fringe orders requires subjective judgement in matching the fringe "colour" to a standardised chart or atlas. In this thesis, a relationship has been developed for white light photoelasticity relating the fringe order to the method by which its colour is represented in a digitised image. (Abstract shortened by UMI.)