Abstract
By using the quadratic spatial filtering (QSF) operation of interferograms, we propose a fast and accurate phase retrieval algorithm in 2-step phase-shifting interferometry (PSI), in which both the interference signal separation and blind phase shift estimation can be realized. Compared with the existed 2-step PSI algorithms, the proposed QSF algorithm reveals two advantages: First, when the background intensity is not accurately estimated, which is a serious problem in 2-step PSI, the distortion of the retrieved phase can be released. Second, there is no requirement about the fringe density of interference pattern, reflecting the phase shift estimation can be realized even if the fringes density is sparse. The former is a valuable solution to reduce most significant errors in 2-step PSI, and the latter makes the accuracy robust against different fringe patterns. Both the simulation and experimental results demonstrate the excellent performance of the proposed QSF algorithm.
Highlights
Phase-Shifting interferometry (PSI), a full-field and quantitative phase measurement technology, has been used in various fields [1], [2] over the past decades
By using the quadratic spatial filtering (QSF) operation of interferograms, we propose a fast and accurate phase retrieval algorithm in 2-step phase-shifting interferometry (PSI), in which both the interference signal separation and blind phase shift estimation can be realized
We propose a new 2-step PSI algorithm based on the quadratic spatial filtering (QSF) of interferograms, in which the phase distortion induced by the background-removal operation can be released by properly using a direct subtracted-interferogram
Summary
Phase-Shifting interferometry (PSI), a full-field and quantitative phase measurement technology, has been used in various fields [1], [2] over the past decades. To remove the error induced by the additional aberration removal procedure, the phase aberration is physically compensated [8], [20], so only the phase induced by the sample can generate fringes and total fringes’ number will become small In this case, many algorithms will encounter accuracy decreasing or even cannot work. A lot of algorithms are proposed to remove the background [41]–[43] and it is assumed that the background intensity is a slowly changed signal relative to the interference intensity, which is not usually valid in practice Another task in 2-step PSI is to blindly estimate the phase shift. We will introduce the details of the proposed QSF algorithm
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