Two-frame phase-shifting interferometry for retrieval of smooth surface and its displacements

An improved windowed Fourier transform filter algorithm

“…The computing time of the WFT filter and the NTWFT filter are 509.14 s and 447.74 s, respectively. Hence, the new algorithm has a better performance in reducing the computing time and the 3D shape measurement in ESPI can be improved by the better filter effect of the wrapped phase map [2][3][4][5].…”

“…Since directly observed output in ESPI is the interference fringe patterns by which the measured object deformation can be determined roughly, various methods to obtain the whole-field phase distribution of a deformed object quantitatively from the interference patterns have emerged including phase-shifting techniques [2][3][4] and carrier technique with Fourier transform [5]. However, due to the inherent noises in speckle fringe pattern, it is hard to extract the phase accurately.…”

Topography, Hardness, Elastic Modulus and Wear Resistance of Nitride Coatings on Titanium

“…The microstructure analysis was determined by Carl Zeiss EVO 40XVP scanning electron microscope with energy dispersive X-ray spectrometer INCA Energy 350. The surface roughness was analyzed with the help of two-step Phase-Shifting interferometry with arbitrary phase shifts [9]. The level of surface hardening after each technological operation was determined by PMT-3M device at the loads on the Vickers indenter of 0.49 and 0.98 N. The nanoindentation was carried out on a Micro Combi Tester device using a diamond Vickers indenter.…”

Phase shifts extraction algorithm based on Gram–Schmidt orthonormalization of two vectors

“…Deng et al (2012) proposed a phase shift extraction algorithm based on calculating the extreme value of interference (EVI) in the interferogram, by searching for the ratio of the extreme values of interference in one interferogram to another interferogram, the phase shift between two interferograms and the measured phase can be determined accurately. Muravsky et al (2011) proposed a two-step algorithm to determine the phase shift by the correlation coefficient of two interferograms (Muravsky and Voronyak 2013). Though almost all of these two-step algorithms are required to eliminate the background of interferograms in advance, it still is a good choice to perform the phase shift extraction with these algorithms because of their convenience, practicability and requirement of fewer frames.…”