The Experts below are selected from a list of 136257 Experts worldwide ranked by ideXlab platform
L Arevalo M Aguilar - One of the best experts on this subject based on the ideXlab platform.
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generalized phase shifting interferometry by parameter estimation with the Least Squares Method
Optics and Lasers in Engineering, 2013Co-Authors: Rigoberto Juarezsalazar, Carlos Robledosanchez, Cruz Menesesfabian, Fermin Guerrerosanchez, L Arevalo M AguilarAbstract:Abstract A simple non-iterative algorithm for generalized phase-shifting interferometry is proposed. This algorithm recovers the wrapped phase from two or more interferograms with unknown phase steps between 0 and π rad. The proposal is based on the Least Squares Method to calculate four parameters: background and modulation light, phase steps and wrapped phase distribution. This algorithm, by a new interferogram normalization procedure, can handle interferograms with variable spatiotemporal visibility overcoming the restriction and drawbacks from usual variable spatial visibility approaches. The algorithm works very well for processing interferograms which include many fringes. This behaviour will be explicated and discussed. The effectiveness and robustness of this algorithm are supported by numerical simulation and by the evaluation of experimental interferograms. The phase-shift estimation quality is verified by two different techniques. By the properties of this algorithm, such as the low computing time and free of user intervention, we believe it could be used in automatic real-time applications.
Liqun Chai - One of the best experts on this subject based on the ideXlab platform.
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phase extraction from randomly phase shifted interferograms by combining principal component analysis and Least Squares Method
Optics Express, 2011Co-Authors: Weimin Jin, Liqun ChaiAbstract:A Method combining the principal component analysis (PCA) and the Least Squares Method (LSM) is proposed to extract the phase from interferograms with random phase shifts. The Method estimates the initial phase by PCA, and then determines the correct global phase sign and reduces the residual phase error by LSM. Some factors that may influence the performance of the proposed Method are analyzed and discussed, such as the number of frames used, the number of fringes in interferogram and the amplitude of random phase shifts. Numerical simulations and optical experiments are implemented to verify the effectiveness of this Method. The proposed Method is suitable for randomly phase-shifted interferograms.
Rigoberto Juarezsalazar - One of the best experts on this subject based on the ideXlab platform.
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generalized phase shifting interferometry by parameter estimation with the Least Squares Method
Optics and Lasers in Engineering, 2013Co-Authors: Rigoberto Juarezsalazar, Carlos Robledosanchez, Cruz Menesesfabian, Fermin Guerrerosanchez, L Arevalo M AguilarAbstract:Abstract A simple non-iterative algorithm for generalized phase-shifting interferometry is proposed. This algorithm recovers the wrapped phase from two or more interferograms with unknown phase steps between 0 and π rad. The proposal is based on the Least Squares Method to calculate four parameters: background and modulation light, phase steps and wrapped phase distribution. This algorithm, by a new interferogram normalization procedure, can handle interferograms with variable spatiotemporal visibility overcoming the restriction and drawbacks from usual variable spatial visibility approaches. The algorithm works very well for processing interferograms which include many fringes. This behaviour will be explicated and discussed. The effectiveness and robustness of this algorithm are supported by numerical simulation and by the evaluation of experimental interferograms. The phase-shift estimation quality is verified by two different techniques. By the properties of this algorithm, such as the low computing time and free of user intervention, we believe it could be used in automatic real-time applications.
René Rotinat - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the Penalized Least Squares Method for Strain Computation
2015Co-Authors: Raphaël Moulart, René RotinatAbstract:This work proposes an alternative procedure to smooth and differentiate experimental full-field displacement measurements to get strain fields. This one, the penalized Least Squares Method, relies on the balance between the fidelity to original raw data and the smoothness of the reconstructed ones. To characterize its performance, a comparative study between this algorithm and two other commonly implemented strategies (the 'diffuse approximation' and the Savitzky-Golay filter) is achieved. The results obtained by the penalized Least Squares Method are comparable in terms of quality of the reconstruction to those produced by the two other algorithms, while the proposed technique is the fastest as its computation time is totally independent from the asked amount of smoothing. Moreover, unlike both other considered Methods, it is possible with this technique to perform the derivation to obtain strain maps before smoothing them (while the smoothing is normally applied to displacement maps before the differentiation) which can lead in some cases to a more effective reconstruction of the strain fields.
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On the use of a penalized Least Squares Method to process kinematic full-field measurements
Measurement Science and Technology, 2014Co-Authors: Raphaël Moulart, René RotinatAbstract:This work is aimed at exploring the performances of an alternative procedure to smooth and differentiate full-field displacement measurements. After recalling the strategies currently used by the experimental mechanics community, a short overview of the available smoothing algorithms is drawn up and the requirements that such an algorithm has to fulfil to be applicable to process kinematic measurements are listed. A comparative study of the chosen algorithm is performed including the 2D penalized Least Squares Method and two other commonly implemented strategies. The results obtained by penalized Least Squares are comparable in terms of quality to those produced by the two other algorithms, while the penalized Least Squares Method appears to be the fastest and the most flexible. Unlike both other considered Methods, it is possible with penalized Least Squares to automatically choose the parameter governing the amount of smoothing to apply. Unfortunately, it appears that this automation is not suitable for the proposed application since it does not lead to optimal strain maps. Finally, it is possible with this technique to perform the derivation to obtain strain maps before smoothing them (while the smoothing is normally applied to displacement maps before the differentiation) which can lead in some cases to a more effective reconstruction of the strain fields.
Weimin Jin - One of the best experts on this subject based on the ideXlab platform.
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phase extraction from randomly phase shifted interferograms by combining principal component analysis and Least Squares Method
Optics Express, 2011Co-Authors: Weimin Jin, Liqun ChaiAbstract:A Method combining the principal component analysis (PCA) and the Least Squares Method (LSM) is proposed to extract the phase from interferograms with random phase shifts. The Method estimates the initial phase by PCA, and then determines the correct global phase sign and reduces the residual phase error by LSM. Some factors that may influence the performance of the proposed Method are analyzed and discussed, such as the number of frames used, the number of fringes in interferogram and the amplitude of random phase shifts. Numerical simulations and optical experiments are implemented to verify the effectiveness of this Method. The proposed Method is suitable for randomly phase-shifted interferograms.