Novel scanning scheme for white light photoelasticity

The use of white light based Twelve Fringe Photoelasticity/RGB Photoelasticity has gained popularity in the recent years. The main advantage of this technique is that it requires only a single image recorded under white light for isochromatic demodulation. This makes it suitable for problems where multiple acquisitions are difficult. Accuracy of fringe order estimation using Twelve Fringe Photoelasticity is dependent on the spatial resolution of the isochromatic fringe pattern. The existing scanning schemes for refining the fringe order data do not take this into account and leads to the propagation of noise from the low resolution zones. In this work, a novel scanning scheme is proposed whose progression is guided by the spatial resolution of the isochromatic fringe pattern. Initially, a method based on the intensity gradients is developed to create a whole field map resembling the resolution of the fringe pattern. This map is used to guide the scanning scheme for refining the fringe order data. The proposed scanning scheme encapsulates the noise within the zones of low spatial resolution and eliminates their propagation. The working of the scanning scheme is demonstrated using the benchmark problem of a circular disc subjected to diameter compression.