Journal ArticleDOI
Phase-unwrapping algorithm by a rounding-least-squares approach
TLDR
A simple and efficient phase-unwrapping algorithm based on a rounding procedure and a global least-squares minimization that operates over the gradient of the phase jumps by a robust and noniterative scheme that could be used in metrological interferometric and fringe-projection automatic real-time applications.Abstract:
A simple and efficient phase-unwrapping algorithm based on a rounding procedure and a global least-squares minimization is proposed. Instead of processing the gradient of the wrapped phase, this algorithm operates over the gradient of the phase jumps by a robust and noniterative scheme. Thus, the residue-spreading and over-smoothing effects are reduced. The algorithm’s performance is compared with four well-known phase-unwrapping methods: minimum cost network flow (MCNF), fast Fourier transform (FFT), quality-guided, and branch-cut. A computer simulation and experimental results show that the proposed algorithm reaches a high-accuracy level than the MCNF method by a low-computing time similar to the FFT phase-unwrapping method. Moreover, since the proposed algorithm is simple, fast, and user-free, it could be used in metrological interferometric and fringe-projection automatic real-time applications.read more
Citations
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Journal ArticleDOI
Phase unwrapping in optical metrology via denoised and convolutional segmentation networks
TL;DR: A new approach is proposed, where the task of phase unwrapping is transferred into a multi-class classification problem and an efficient segmentation network is introduced to identify classes and a noise-to-noise denoised network is integrated to preprocess noisy wrapped phase.
Journal ArticleDOI
Theory and algorithms of an efficient fringe analysis technology for automatic measurement applications
TL;DR: A full scheme for phase evaluation, applicable to automatic applications, is proposed, which consists of a fringe-pattern normalization method, Fourier fringe-normalized analysis, generalized phase-shifting processing for inhomogeneous nonlinear phase shifts and spatiotemporal visibility, and a phase-unwrapping method by a rounding-least-squares approach.
Journal ArticleDOI
The depth measurement of internal defect based on laser speckle shearing interference
TL;DR: In this article, a method of the depth measurement of internal defect based on laser speckle shearing interference is proposed, where the measurement of defect depth is achieved by establishing the mechanical model which contains defect depth, out-of-plane displacement and load conditions, and combining the relevant image information obtained from specckle pattern.
Journal ArticleDOI
Camera calibration by multiplexed phase encoding of coordinate information.
Rigoberto Juarez-Salazar,Fermin Guerrero-Sanchez,Carlos Robledo-Sanchez,Jorge González-García +3 more
TL;DR: A simple camera calibration method based on the principle of phase encoding and coordinate transformation that could be used to calibrate fringe-projection systems and a robust and noniterative estimation scheme is obtained.
Journal ArticleDOI
How do phase-shifting algorithms work?
Rigoberto Juarez-Salazar,Ceciibet Mendoza-Rodriguez,Jose Enrique Hernandez-Beltran,Carlos Robledo-Sanchez +3 more
TL;DR: In this article, the fundamental principles behind seven well-established phase-shifting algorithms are presented, and five basic algorithms are analyzed: the three-, four-, and n-steps as well as two least squares algorithms.
References
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Journal ArticleDOI
Solution of the matrix equation AX + XB = C [F4]
R. H. Bartels,G. W. Stewart +1 more
TL;DR: The algorithm is supplied as one file of BCD 80 character card images at 556 B.P.I., even parity, on seven ~rack tape, and the user sends a small tape (wt. less than 1 lb.) the algorithm will be copied on it and returned to him at a charge of $10.O0 (U.S.and Canada) or $18.00 (elsewhere).
Journal ArticleDOI
A novel phase unwrapping method based on network programming
TL;DR: A new phase unwrapping method is described and tested, which starts from the fact that the phase differences of neighboring pixels can be estimated with a potential error that is an integer multiple of 2/spl pi/.
Journal ArticleDOI
Robust two-dimensional weighted and unweighted phase unwrapping that uses fast transforms and iterative methods
TL;DR: In this article, a robust method for 2D phase principal values (in a least-squares sense) by using fast cosine transforms was developed, which can be used to isolate inconsistent regions (i.e., phase shear).
Journal ArticleDOI
A Hessenberg-Schur method for the problem AX + XB= C
TL;DR: A new method is proposed which differs from the Bartels-Stewart algorithm in that A is only reduced to Hessenberg form, and the resulting algorithm is between 30 and 70 percent faster depending upon the dimensions of the matrices A and B.
Journal ArticleDOI
Temporal phase-unwrapping algorithm for automated interferogram analysis.
TL;DR: An alternative approach based on one-dimensional unwrapping along the time axis is proposed, applicable to an important subclass of interferometry applications, in which a sequence of incremental phase maps can be obtained leading up to the final phase-difference map of interest.