Effect of camera spatial resolution on fringe contrast in digital speckle correlation interferometry

In digital speckle correlation interferometry, the camera used is typically unable to fully resolve the speckle pattern. Consequently, there is often a tendency to utilize cameras with better spatial resolution in order to obtain improved fringe contrast signals. However, it is demonstrated in this paper that the fringe contrast signal is effectively independent of camera spatial resolution. In fact, the use of higher spatial resolution cameras may even result in a catastrophic corruption of the fringe contrast against deformation phase waveform if the magnitudes of phase fluctuation are sufficiently large.