Guillermo H Kaufmann

Guillermo H Kaufmann
Instituto de Física Rosario · Optical Metrology Laboratory

PhD, Prof. Applied Optics, Chief Scientist CONICET

About

179
Publications
7,883
Reads
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2,610
Citations
Additional affiliations
March 2008 - February 2016
Centro Internacional Franco-Argentino de Ciencias de la Información y de Sistemas
Position
  • Managing Director
Description
  • Research centre on Information and systems sciences, which depends of CONICET and Universidad Nacional de Rosario. From 2012 to 2015 it was an international laboratory associated to the Centre National de la Recherche Scientifique (CNRS) of France.

Publications

Publications (179)
Article
Full-text available
We test the performance of a phase recovery method based on a three-dimensional directional wavelet transform applied to the intensity signal measured by temporal speckle pattern interferometry (TSPI). We present and discuss several sources of uncertainty by analyzing experimental datasets recorded for an in-plane interferometer without introducing...
Article
Full-text available
In digital speckle pattern interferometry, fringeless speckle pattern interferograms are obtained when the object field deformation is insufficient to produce local phase variations higher than 2 π . Therefore, the use of the well-known phase recovery algorithms based on fringe processing is not adequate. In this work, distinct algorithms based on...
Article
An analysis based on the comparison between singularities of speckle phase and pseudophase in the practice of optical vortex metrology is carried out by measuring the phase map of the speckle pattern obtained from the transmitted light through binary diffusers. In the characterization of the core structure of both phase singularities, the variation...
Article
Full-text available
Spiral interferometry can be used as a solution to the problem of sign ambiguity presented in the conventional speckle pattern interferometric technique when the optical phase needs to be reconstructed from a single closed fringe system. Depressions and elevations of the topography corresponding to the object deformation are distinguished by the di...
Article
Full-text available
Three real-time methods for object-phase recovery are implemented and compared in temporal speckle-pattern interferometry. Empirical mode and intrinsic time-scale decompositions are used and compared as real-time nonstationary and nonlinear filtering techniques for the extraction of the spatio-temporal evolution of the object phase. The proposed re...
Article
Full-text available
This paper presents a method for amplitude and phase retrieval in simultaneous π / 2 phase-shifting heterodyne interferometry. The used optical setup admits the introduction of a temporal carrier and simultaneously verifies the two-beam interferometry equation for each intensity signal, which are π / 2 rad out of phase (quadrature). The spatiotempo...
Article
Full-text available
A simplified method for object phase recovering is implemented in temporal speckle pattern interferometry when the employed interferometer admits the introduction of a temporal carrier, and the well-known two-beam interferometry equation is verified. The spatiotemporal evolution of the object phase is isolated by modulating the acquired interferome...
Article
Full-text available
We present a method to determine micro and nano in-plane displacements based on the phase singularities generated by application of directional wavelet transforms to speckle pattern images. The spatial distribution of the obtained phase singularities by the wavelet transform configures a network, which is characterized by two quasi-orthogonal direc...
Article
Full-text available
We evaluate the extension of the exact nonlinear reconstruction technique developed for digital holography to the phase-recovery problems presented by other optical interferometric methods, which use carrier modulation. It is shown that the introduction of an analytic wavelet analysis in the ridge of the cepstrum transformation corresponding to the...
Article
Using data sets recorded from a speckle interferometer with in-plane sensitivity, we compare the performance of a recently proposed temporal phase evaluation technique based on the three-dimensional directional wavelet transform with the one given by the one-dimensional Fourier transform method. The obtained results are compared for different phase...
Article
Full-text available
This paper presents a method to measure nanometric displacement fields using digital speckle pattern interferometry, which can be applied when the generated correlation fringes show less than one complete fringe. The method is based on the evaluation of the correlation between the two speckle interferograms generated by both deformation states of t...
Article
This chapter reviews various algorithms for processing temporal speckle pattern interferometry (TSPI) signals, which were developed mostly during the last decade. The development of experimental techniques aiming the reduction of decorrelation effects in speckle fields. However, the approach adopted in the chapter is the estimation of the phase cod...
Article
This paper presents an interferometric measurement of the out-of-plane deflections produced by a piezoelectric transducer, manufactured by thick-film deposition of a ceramic paste over an alumina substrate, when is subjected to a DC electric voltage. It is shown that a digital speckle pattern interferometer with an incorporated phase-shifting facil...
Article
Full-text available
We propose a phase measurement technique to retrieve optical phase distributions coded in noisy temporal speckle pattern interferometry signals presenting regions of adjacent low-modulated pixels, which is based on the bidimensional empirical mode decomposition and the Hilbert transform. It is shown that this approach can effectively remove noise a...
Article
Samples of AISI 316 Stainless Steel were nitrogen and argon ion implanted with pulsed beams generated with a Plasma Gun operated in the detonation mode. The residual deformations induced by the beams were studied by double exposure (before and after implantation) holographic interferometry. The results showed residual deformations corresponding to...
Conference Paper
Carbon fiber reinforced polymers have become thicker due to its use in aircraft manufacturers. Their manufacturing processes implies the generation of important residual stresses. In this work, a L-shaped thick composite shell is analyzed under moderate temperature changes. A stacking sequence error is voluntarily added in order to simulate possibl...
Article
We compare the performance of various recently-developed phase recovery approaches when they are applied in temporal speckle pattern interferometry. The phase retrieval methods to be evaluated are based on the 1D continuous wavelet, the Hilbert-Huang and the S-transforms, and the smooth time-frequency distribution. It is shown that the 3D direction...
Article
Full-text available
This paper presents a novel technique to investigate coating adhesion using a radial speckle interferometer and a microindentation test. The proposed technique is based on the measurement of the radial in-plane displacement field produced by a microindentation introduced on the coated surface of the specimen. The advantages and limitations of the p...
Article
Full-text available
We evaluate and compare the use of competitive neural networks, self-organizing maps, the expectation-maximization algorithm, K-means, and fuzzy C-means techniques as partitional clustering methods, when the sensitivity of the activity measurement of dynamic speckle images needs to be improved. The temporal history of the acquired intensity generat...
Article
Full-text available
We evaluate a data-driven technique to perform bias suppression and modulation normalization of fringe patterns. The proposed technique uses a bidimensional empirical mode decomposition method to decompose a fringe pattern in a set of intrinsic frequency modes and the partial Hilbert transform to characterize the local amplitude of the modes in ord...
Article
The definition of adhesion is not a simple issue and its characterization generates considerable debate in the technical literature [1]. Many of the existing tests to determine the adhesion of a given coating-substrate combination are qualitative or semi-quantitative and the adhesion is assessed from the appearance of the fracture surface [2].
Article
Phase extraction techniques in fringe analysis are very sensitive to noise but also to modulation defects mostly due to non-uniform illumination. For this reason, in many cases the fringe pattern modulation must be normalized before the phase map is extracted in order to avoid the introduction of large errors in the demodulated phase.
Article
Full-text available
We propose an approach based on a 3D directional wavelet transform to retrieve optical phase distributions in temporal speckle pattern interferometry. We show that this approach can effectively recover phase distributions in time series of speckle interferograms that are affected by sets of adjacent nonmodulated pixels. The performance of this phas...
Article
Full-text available
Tilt scanning interferometry (TSI) is a novel experimental technique that allows the measurement of multicomponent displacement fields inside the volume of a sample. In this paper, we present a simulation model that allows for the evaluation of the speckle fields recorded in TSI when this technique is applied to the analysis of semitransparent scat...
Article
This paper presents a technique to investigate the adhesion of thin coatings which combines digital speckle pattern interferometry and an indentation test. The proposed approach is based on the measurement of the local displacement field produced by a microindentation introduced on the coated surface of a specimen. It is experimentally demonstrated...
Book
Full-text available
Due to the impulsion of aircraft manufacturers, Carbon Fiber Reinforced Polymers have become thicker. But the manufacturing process still implies the development of important residual stresses, either due to moisture effects or thermal effects [I]. If the symmetry of the composite part is broken, the global part shape will be affected by any moistu...
Article
Full-text available
We evaluate a method based on the two-dimensional directional wavelet transform and the introduction of a spatial carrier to retrieve optical phase distributions in singular scalar light fields. The performance of the proposed phase-retrieval method is compared with an approach based on Fourier transform. The advantages and limitations of the propo...
Article
Full-text available
We present an introduction to the Bidimensional Empirical Mode Decomposition (BEMD) and its application to the denoising of DSPI fringes. The BEMD is based on the decomposition of an image in high and low frequency zero-mean oscillation modes, called intrinsic mode functions (IMFs). The decomposition is carried out through a sifting process which p...
Article
Full-text available
We propose a bidimensional empirical mode decomposition (BEMD) method to reduce speckle noise in digital speckle pattern interferometry (DSPI) fringes. The BEMD method is based on a sifting process that decomposes the DSPI fringes in a finite set of subimages represented by high and low frequency oscillations, which are named modes. The sifting pro...
Article
Full-text available
We propose a novel approach based on the generalized S-transform to retrieve optical phase distributions in temporal speckle pattern interferometry. The performance of the proposed approach is compared with those given by well-known techniques based on the continuous wavelet, the Hilbert transforms, and a smoothed time-frequency distribution by ana...
Article
Full-text available
We present an optical phase measurement method based on the Hilbert transform for the analysis of a time series of speckle interferograms modulated by a temporal carrier. We discuss the influence of nonmodulating pixels, modulation loss, and noise that affect the bias and modulation intensities of the interferometric signal and propose the applicat...
Article
Full-text available
When the phase distribution is evaluated in temporal speckle pattern interferometry by means of the Hilbert transform method, the accuracy of the estimation is conditioned by the influence of the variations of the bias and the modulation intensities, since these parameters must be selected heuristically. In this work we present a novel approach th...
Article
This paper presents a feasibility study to assess whether digital speckle pattern interferometry could be used as a possible technique to investigate the adhesive performance of coatings. The approach is based on the measurement of the deflections produced by a pre-notched coated specimen subjected to a four-point bending test. When the bending loa...
Article
This paper presents the evaluation of a removal method to cancel the thermal convection effect that is generated in vertically positioned metal plates loaded by thermal waves when a lock-in temporal speckle pattern interferometry technique is used to detect hidden flaws. Additionally, the resolution of this technique to detect two nearby flaws is a...
Article
When the Hilbert transform method is used to recover the phase distribution in temporal speckle pattern interferometry, the influence of the fluctuations of the bias and the modulation intensities on the calculated phase must be driven heuristically. In this paper we show that the Empirical Mode Decomposition method can overcome these drawbacks and...
Article
A lockin method which takes into account the contribution of several modes from the Fourier spectrum generated by a heat load following a triangular waveform is used in temporal speckle pattern interferometry (TSPI) for the nondestructive detection of defects. By defining a parameter to quantify defect detectability, it is demonstrated that the use...
Article
The 1D empirical mode decomposition method is applied to reduce speckle noise in the correlation fringes produced in digital speckle pattern interferometry. This method is based on the decomposition of a signal in a sum of well-behaved fast and slow oscillation modes through a sifting process, which generates a fully data-driven technique. Conseque...
Article
Full-text available
We present an effective method for speckle noise removal in digital speckle pattern interferometry, which is based on a wave-atom thresholding technique. Wave atoms are a variant of 2D wavelet packets with a parabolic scaling relation and improve the sparse representation of fringe patterns when compared with traditional expansions. The performance...
Article
Full-text available
We propose the application of a method based on the discrete wavelet transform to detect, identify, and measure scaling behavior in dynamic speckle. The multiscale phenomena presented by a sample and displayed by its speckle activity are analyzed by processing the time series of dynamic speckle patterns. The scaling analysis is applied to the tempo...
Article
The detection of internal defects using digital speckle pattern interferometry (TSPI) combined with thermal loading has generated great interest in the field of non-destructive testing. Recently, Kaufmann et al have shown that the technique called temporal speckle pattern interferometry can be used to visualise time-dependent deformations generated...
Article
In the last decade, Huang et al. [1] presented a non-linear method called Empirical Mode Decomposition (EMD) for adaptively representing a non-stationary signal as a sum of zero-mean well-behaved fast and slow oscillation empirical modes, which are known as Intrinsic Mode Functions (IMFs). An IMF is a function that satisfies two conditions: (1) in...
Article
Full-text available
We propose the display of the local spatial variance of the temporal variations of the phase as an activity descriptor in dynamic speckle images. The spatial autocorrelation of the speckle intensity is calculated in sliding windows, and an estimation of the variance of the phase variations in each region of the sample is determined. The activity im...
Article
This paper presents the evaluation of a method to cancel rigid body displacements that can be introduced when a hole drilling and digital speckle pattern interferometry (DSPI) combined system is used to measure residual stresses. The proposed method is based on a least-square calculation of three correction parameters determined from two evaluation...
Article
The empirical mode decomposition (EMD) method is used to process sequences of dynamic speckle patterns to segment the differential activity that presents a sample as a function of the spatial coordinates and time. The application of the method is illustrated by segmenting bruised regions in fruits. A discussion of the obtained results and a compari...
Article
This paper presents a portable device to measure residual stresses using the hole drilling technique combined with digital speckle pattern interferometry. This device, which is based on only one dual-beam illumination system, allows the determination of the three components of the residual stress from the measured displacement field generated by th...
Conference Paper
In recent years, the fractal theory has been applied to a wide variety of scientific problems. However, this approach has not been used to study dynamic processes through the analysis of temporal sequences of speckle patterns. In this work we present a study of the dynamic speckle phenomenon based on the multifractal theory. This study is carried o...
Conference Paper
When the speckle pattern produced by a scattering surface shows some type of activity, the speckle distribution changes in time. This paper presents a method to locally estimate the spatial variance of the temporal variation of the phase as an activity descriptor in a sequence of dynamic speckle. This method is based on the computation of the spati...
Article
The Young's modulus and the Poisson's ratio of an isotropic material are measured using digital speckle pattern interferometry. The technique is based on the determination of the permanent local displacement field generated in a specimen after it is plastically deformed with a spherical indenter. Using a phase shifting technique and a phase unwrapp...
Article
Dynamic speckle has been used in recent years to analyse several transient processes that are produced in industrial and biological applications. We present here a numerical simulation to generate a temporal sequence of dynamic speckle patterns which is based on a model used for speckle formation by the superposition of waves from discrete scatteri...
Article
Full-text available
We propose a novel approach to retrieving the phase map coded by a single closed-fringe pattern in digital speckle pattern interferometry, which is based on the estimation of the local sign of the quadrature component. We obtain the estimate by calculating the local orientation of the fringes that have previously been denoised by a weighted smoothi...
Article
We present the application of a portable radial in-plane speckle interferometer to the measurement of residual stresses when local heating is used as a stress relaxation technique. We also present a numerical method to calculate the residual stresses from the radial in-plane displacement field that is measured subsequent to the heating and cooling...
Article
Full-text available
The recently developed technique of high-speed phase-shifting speckle interferometry combined with temporal phase unwrapping allows dynamic displacement fields to be measured, even for objects containing global discontinuities such as cracks or boundaries. However, when local speckle averaging is included, small phase errors introduced at each time...
Article
Full-text available
We evaluate the use of smoothing splines with a weighted roughness measure for local denoising of the correlation fringes produced in digital speckle pattern interferometry. In particular, we also evaluate the performance of the multiplicative correlation operation between two speckle patterns that is proposed as an alternative procedure to generat...
Article
This paper presents an application of a radial in-plane digital speckle pattern interferometer and a local heating combined system to measure residual stresses in ductile materials. The system allows the local heating of a small spot and the measurement of the radial in-plane displacement field generated around it. In order to quantify the residual...
Article
This presentation reviews recent developments carried out by the authors to evaluate phase distributions in digital speckle pattern interferometry (DSPI) using wavelet analysis. The advantage of this approach is that it requires only one interferogram to be analyzed and does not need the application of a phase unwrapping algorithm neither the intro...
Article
This paper presents a combined system based on DSPI and local heating, which alows the evaluation of residual stresses. To determine the residual stress values, a finite element analysis (FEA) of the thermomechanical process is carried out. The feasibility of this approach is demonstrated by comparing the results obtained from measurements in a pre...
Article
We evaluate the application of the Wigner-Ville distribution (WVD) to measure phase gradient maps in digital speckle pattern interferometry (DSPI), when the generated correlation fringes present phase discontinuities. The performance of the WVD method is evaluated using computer-simulated fringes. The influence of the filtering process to smooth DS...
Article
This paper presents a temporal speckle pattern interferometry (TSPI) system which uses thermal waves to detect internal defects. The system allows the measurement of out-of-plane thermoelastic displacements generated when a specimen is locally heated with a temporally modulated CO2 laser. The defects can be detected by observing the perturbations w...
Article
This paper presents a combined system based on digital speckle pattern interferometry and laser annealing to determine residual stresses in ductile materials. The system allows the measurement of the radial in-plane displacement field generated when a specimen subjected to residual stresses is locally heated. This novel approach for measuring resid...
Article
Full-text available
A digital image measurement (DIM) system is used to study the plastic damage accumulation around a notch under conditions of low-cycle fatigue. This system incorporates a contrast correlation method to evaluation the level of plastic damage at each point of the studied area from two images acquired before and after the introduction of fatigue defor...
Article
We describe a temporal speckle pattern interferometry (TSPI) system to be used for the detection of internal defects. Stressing of the flawed specimen is introduced using a temporally modulated CO2 laser, which locally heats its surface. The resulting out-of-plane thermoelastic deflection is measured using the TSPI system. The speckle interferogram...
Article
The fatigue damage accumulation process around a notch is studied using a noncontact digital image measurement system. This system incorporates a contrast correlation method to evaluate the level of plastic damage at each point of the studied area of the specimen from two images acquired before and after the introduction of fatigue deformation. A c...
Article
This paper reports on the accuracy and sensitivity of digital speckle pattern interferometry (DSPI) when it is combined with the hole drilling technique for measuring residual stresses. The in-plane displacement field generated by the introduction of a small hole is determined using an automated data analysis approach. This method is based on the c...
Article
Full-text available
We evaluate the use of a smoothed space-frequency distribution (SSFD) to retrieve optical phase maps in digital speckle pattern interferometry (DSPI). The performance of this method is tested by use of computer-simulated DSPI fringes. Phase gradients are found along a pixel path from a single DSPI image, and the phase map is finally determined by i...
Article
A high-speed phase-shifted speckle interferometer has been developed recently for studying dynamic events. Speckle interferograms are continuously recorded by a CCD camera operating at 1 kHz with temporal phase shifting carried out by a Pockels cell running at the same frequency. Temporal phase unwrapping through sequences of more than 1000 frames...
Article
The temporal phase unwrapping algorithm (TPUA) can be interpreted as a phase accumulation process that can be reinitialized at specific time intervals. As a new reference can be taken after some pre-defined time, it is important to know how this time intervals influence the accuracy of the TPUA. An error analysis is then necessary to determine an o...
Article
A novel temporal phase shifting method that searches for the peak of the windowed Fourier transform of the modulated intensity signal and evaluates the phase over that frequency instead over the carrier frequency is presented.
Article
A temporally modulated IR lamp is employed to heat the surface of a flawed plate and the resulting out-of-plane thermoelastic deflection is monitored using phase-shifted temporal speckle pattern interferometry. The speckle interferograms are continuously recorded by means of a high-speed digital camera with temporal phase shifting carried out by a...
Article
In this paper we analyze the application of a chirped Gaussian wavelet transform to retrieve the phase distribution in digital speckle pattern interferometry (DSPI). The performance of this method is evaluated using computer-simulated fringes, approach that allows an accurate determination of the phase map encoded by the fringe pattern. It is shown...
Article
Temporal phase-shifting speckle interferometry (TPSSI) is a technique based on the recording of a sequence of speckle interferograms throughout the entire deformation history of an object. To calculate the phase map, a controlled phase change is introduced in the reference beam as a function of time. As temporal phase unwrapping involves only one-d...
Article
In this paper we analyze the application of a chirped Gaussian wavelet transform to retrieve the phase distribution in digital speckle pattern interferometry (DSPI). The performance of this method is evaluated using computer-simulated fringes, approach that allows an accurate determination of the phase map encoded by the fringe pattern. It is shown...
Article
Full-text available
Most standard temporal-phase-shifting (TPS) algorithms evaluate the phase by computing a windowed Fourier transform (WFT) of the intensity signal at the carrier frequency of the system. However, displacement of the specimen during image acquisition may cause the peak of the transform to shift away from the carrier frequency, leading to phase errors...
Article
The combination of speckle pattern interferometry and temporal phase unwrapping allows the measurement of large-object dynamic displacements without the propagation of spatial unwrapping errors. For retrieving phase data for whole-object displacement, the temporal Fourier transform method is a commonly used approach. As the temporal Fourier transfo...
Article
Full-text available
The measurement of dynamic displacements by use of speckle pattern interferometry and temporal phase unwrapping allows for the evaluation of large-object displacement fields without the propagation of spatial unwrapping errors. If a temporal carrier is introduced in one of the beams of the interferometer, phase data for whole-object displacement ca...
Article
We present an evaluation of the continuous wavelet transform method when it is used to measure the phase distribution encoded by electronic speckle pattern interferometry (ESPI) fringes. The evaluation is performed using computer-simulated fringes, an approach that allows knowing precisely the phase map contained in the pattern. It is shown that on...
Article
Full-text available
The influence of random vibrations on the performance of a dynamic phase-shifting speckle pattern interferometer is investigated by means of experiments and numerical simulations. Two aspects are evaluated: first, temporal unwrapping reliability, second, vibration-induced phase noise. The former is found to be a significant constraint, even for pea...