New contra old wavefront measurement concepts for interferometric optical testing

Moving ahead with phase

“…These algorithms termed as self-compensating [30,[45][46][47] have proved to be effective in compensating deterministic phase shift error, and in compensating even second order nonlinearities [55,63,64]. Some of these algorithms minimize the effect of other systematic errors such as optical system aberrations [53,65], parasitic fringes [43,66], photodetection errors [64,67] and quantization errors [52,68]. Random errors due to thermal or shot noise have also been observed to influence the phase measurement [56].…”

“…Although three frames are normally sufficient for estimating the phase, it has now become a well-established fact that additional data frames need to be acquired to minimize the effects of various systematic [41][42][43][44][45][46][47][48][49][50][51][52][53] and random errors [54][55][56][57][58][59]. The use of large number of data frames has been shown to decrease the sensitivity to these errors.…”

<title>Two-directional spatial-carrier phase-shifting method for analysis of complex interferograms</title>

“…determination of common area of I, and b,, (O 0)• Calculating linear and constant terms for both functions within the O r-O, 5. adjusting the linear and constant terms of according to reference values of these terms obtained for 6. combining function with the corrected to fill the gaps in I, within an interferogram domain (Fig.…”

<title>Expert system for analysis of complicated fringe patterns</title>

“…The system was successfully used for shape measurement using projection moire or fringe projection systems [7], composite materials testing by moire interferometry [8], conventional interferometry [5] or more complex algorithm for refractive index measurement by various methods [91.…”