Windowed phase unwrapping using a first-order dynamic system following iso-phase contours

Estrada, J. C.; Vargas, Javier; Flores-Moreno, J. M.; Quiroga, Juan Antonio

doi:10.1364/ao.51.007549

Cited by 14 publications

(6 citation statements)

References 21 publications

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“…First, the dislocations maps   , xy  can be filtered and smoothed using a Zernike fitting approach. Secondly, these dense displacements maps can be efficiently unwrapped using the methods presented in [15,16] that correspond to fast unwrapping two-dimensional algorithms based on linear recursive filters. These recursive filters can be seen as composed by two terms: a predictor, that is an estimation based on previously unwrapped values, and a corrector, that takes into account wrapped input data to correct the current estimation.…”

Section: Proposed Methodsmentioning

confidence: 99%

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Shack-Hartmann spot dislocation map determination using an optical flow method

Vargas¹,

Restrepo²,

Belenguer³

2014

Opt. Express

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We present a robust, dense, and accurate Shack-Hartmann spot dislocation map determination method based on a regularized optical flow algorithm that does not require obtaining the spot centroids. The method is capable to measure in presence of strong noise, background illumination and spot modulating signals, which are typical limiting factors of traditional centroid detection algorithms. Moreover, the proposed approach is able to face cases where some of the reference beam spots have not a corresponding one in the distorted Hartmann diagram, and it can expand the dynamic range of the Shack-Hartmann sensor unwrapping the obtained dense dislocation maps. We have tested the algorithm with both simulations and experimental data obtaining satisfactory results. A complete MATLAB package that can reproduce all the results can be downloaded from [http://goo.gl/XbZVOr].

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Section: Proposed Methodsmentioning

confidence: 99%

“…Note that these dislocation maps are dense but appears wrapped because the limited dynamic range of the SH sensor. In order to unwrapping these maps, we have used a similar method that the one presented in [8] but we have used the unwrapping approach presented in [15,16], that is very fast and robust to noise. In Figs …”

Section: Simulationsmentioning

confidence: 99%

Shack-Hartmann spot dislocation map determination using an optical flow method

Vargas¹,

Restrepo²,

Belenguer³

2014

Opt. Express

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“…9 Extract a window of certain size from the images, use first-order dynamic unwrapping to obtain the phase of the window, and then move the window to an adjacent position and unwrap again. Since a certain region may perform multiple times of unwrap and correction, this redundancy increases the stability of dynamic unwrap system.…”

Section: Introductionmentioning

confidence: 99%

Fast phase unwrapping algorithm based on region partition for structured light vision measurement

2014

Opt. Eng

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Phase unwrapping is a key problem of phase-shifting profilometry vision measurement for complex object surface shapes. The simple path-following phase unwrapping algorithm is fast but has serious unwrapping error for complex shapes. The Goldstein+flood phase unwrapping algorithm can handle some complex shape object measurement; however, it is time consuming. We propose a fast phase unwrapping algorithm based on region partition according to a quality map of wrapped phase. In this algorithm, wrapped phase image is divided into several regions using partition thresholds, which are determined according to histogram of quality value. Each region is unwrapped by using a simple path-following phase algorithm and several groups with different priorities are generated. These groups are merged according to their priorities from high to low order and a final absolute phase is obtained. The proposed method is applied to wrapped phase images of three objects with and without noise. Experiments show that the proposed method is much faster, more accurate, and robust to noise than the Goldstein+flood algorithm in unwrapping complex phase image.

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“…The last category is denoising-unwrapping methods. [26][27][28][29] This type of methods performs phase map denoising to remove noise from wrapped phase by using a filtering process. The filtering process is sometimes applied before the unwrapping process such as windowed Fourier transform method, 26 or it is applied simultaneously with the unwrapping process such as dynamic filter method.…”

Section: Introductionmentioning

confidence: 99%

Phase extraction and unwrapping using rotational and direct compensators for digital hologram

2013

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Abstract. The growing interest in the applications of digital holography interferometry has led to an increasing demand for reliable phase unwrapping techniques. In digital holography, the phase carries three-dimensional surface information about the object. However, phase mapping is ambiguous as the extracted phase is returned in a form that suffers from 2π phase jumps. Furthermore, the presence of noise in the measured data, in which many singular points (SP) are found, often makes general phase unwrapping algorithms fail to produce accurate unwrapped results. Therefore, it is necessary to use a powerful phase unwrapping method to recover the desired smooth phase surface. For this reason, we developed a phase unwrapping algorithm that is applicable to digital hologram maps. The developed algorithm solves the singularity problem caused by SPs as a result of compensating its effect by using rotational and direct compensators. We show a difference in performance between our developed phase unwrapping algorithm and other well known phase unwrapping methods for digital holographic data. In addition, the methods to extract phase information of the object from hologram maps are also investigated. Results show that the developed algorithm gives satisfactory unwrapped results with low computational time cost. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Windowed phase unwrapping using a first-order dynamic system following iso-phase contours

Cited by 14 publications

References 21 publications

Shack-Hartmann spot dislocation map determination using an optical flow method

Shack-Hartmann spot dislocation map determination using an optical flow method

Fast phase unwrapping algorithm based on region partition for structured light vision measurement

Phase extraction and unwrapping using rotational and direct compensators for digital hologram

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