On the Use of Different Wavelengths to Digitally Determine the Isochromatic Fringe Order

Data Acquisition Techniques in Photoelasticity

“…Another possibility for obtaining the phase‐shifted images necessary in the “phase shifting” technique was to use different loads (load stepping) 79–85 or different wavelengths (wavelength stepping) 86–90 instead of employing different positions of the filters (phase stepping). These new approaches surmounted the limitations of the unwrapping process in “phase stepping.” Research continues to this day in order to improve all these “phase shifting” techniques, which offer great potential: the use of white light and the combination with other techniques (as will be seen later on) substantially improve the technique.…”

“…(wavelength stepping) [86][87][88][89][90] instead of employing different positions of the filters (phase stepping). These new approaches surmounted the limitations of the unwrapping process in ''phase stepping.''…”