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Showing papers in "Optics and Lasers in Engineering in 2011"


Journal ArticleDOI
TL;DR: A reliability-guided displacement scanning strategy is employed to avoid time-consuming integer–pixel displacement searching for each calculation point, and a pre-computed global interpolation coefficient look-up table is utilized to entirely eliminate repetitive interpolation calculation at sub-pixel locations.

217 citations


Journal ArticleDOI
TL;DR: In this paper, optical process monitoring of layerwise laser melting has been applied using a high speed near-infrared CMOS camera and a large area silicon photodiode sensor, where the geometric influencing factors can be studied and quantified by analyzing the melt pool sensor output.

146 citations


Journal ArticleDOI
TL;DR: Optical coherence tomography (OCT) and terahertz pulsed imaging (TPI) are two powerful techniques allowing high quality cross-sectional images from within scattering media to be obtained non-destructively as mentioned in this paper.

129 citations


Journal ArticleDOI
TL;DR: In this paper, a model to estimate the main dimensions (depth and width) of the grooves produced by the laser on PMMA is presented, taking into account the influence of the main process parameters (incident power, scanning speed and spot diameter).

120 citations


Journal ArticleDOI
TL;DR: An iterative structure of image encryption is designed for introducing more random phases to encrypt image using the random phase encoding method in gyrator domains generated by a two-dimensional chaotic mapping with the help of computer.

109 citations


Journal ArticleDOI
TL;DR: This research proposes a new finger vein image restoration method to deal with skin scattering and optical blurring, and shows that the equal error rate (EER) of finger vein recognition with restoration was reduced by as much as 3.14% compared to the EER without restoration.

95 citations


Journal ArticleDOI
TL;DR: The work presented in this paper aims at improving the accuracy of non-contact measurement techniques through an error correction procedure based on an experimental process that concerns mechanical parts, and shows an improvement of the results of the correction.

89 citations


Journal ArticleDOI
TL;DR: A fast and accurate rail wear measurement method based on simple equipments that simplifies the problem of computing rail wear from 2d image processing to 1d searching along the line segment connecting two rail wear constraint points.

81 citations


Journal ArticleDOI
TL;DR: In this article, a wavelet-transformed ultrasonic propagation imaging method was proposed for automatic inspection of in-service engineering structures, or in-process quality inspection in manufacturing.

76 citations


Journal ArticleDOI
TL;DR: In this article, the effects of pulse duration and overlapping factor on the microstructure and hardness of the alloyed layer were deduced from Vickers micro-indentation tests, XRD, SEM and metallographic analyses of cross sections of the generated layer.

68 citations


Journal ArticleDOI
TL;DR: In this article, an experimental and theoretical investigation into the phenomenon of "striation free cutting", which is a feature of fiber laser/oxygen cutting of thin section mild steel, is presented.

Journal ArticleDOI
TL;DR: In this paper, conditions of the laser-aided formation of nanoporous structures with nanopores ranging in size from 40 to 50nm using laser pulses of 10.6μm wavelength at a pulse-repetition rate of up to (4-5)×103

Journal ArticleDOI
TL;DR: In this article, the authors deal with the control of springback phenomena in the bending process of aluminium sheets by hybrid forming process, where metal substrates were pre-bent to nominal shapes on a built-ad-hoc mold after being constrained on it.

Journal ArticleDOI
TL;DR: A method for improving the output of a CMM mounted laser line scanner for metrology applications is introduced by filtering of the scanner's random error and by combination with widely spread and reliable but slow touch trigger probing.

Journal ArticleDOI
TL;DR: In this article, the impact of a non-perpendicular camera alignment to a planar sheet metal specimen's surface is estimated in a numerical experiment and it is shown that a 3D-DIC stereo configuration induces a substantial compensation for the introduced imageplane displacement gradients.

Journal ArticleDOI
TL;DR: In this article, the micro-scale mechanical behavior of a polymer-bonded explosive (PBX) simulant was experimentally studied using a scanning electron microscope (SEM) imaging system and digital image correlation (DIC) method.

Journal ArticleDOI
TL;DR: This paper presents a novel approach for the automatic localization of pupil and iris using Eccentricity based Bisection method which looks for the region that has the highest probability of having pupil.

Journal ArticleDOI
TL;DR: A novel method for rapid and flexible laser marking and engraving of tilted, curved and freeform work-piece surfaces based on integrating a three-dimensional laser measurement system into a 3D laser marking system is presented.

Journal ArticleDOI
TL;DR: In this paper, a portable long distance ultrasonic propagation imaging (LUPI) system was proposed to excite, from a long distance, acoustic emission sensors installed in the turbine blade.

Journal ArticleDOI
TL;DR: In this article, two L27 Taguchi experiments were carried out to study the effect of fiber laser welding parameters and their interactions upon the weld bead aspect ratio of nickel-titanium thin foil.

Journal ArticleDOI
TL;DR: In this paper, a laser-induced breakdown spectroscopy (LIBS) is used for measuring the concentration of cement ingredient in a cement powder and a microplasma is formed in the front of samples.

Journal ArticleDOI
TL;DR: Experiments show that the single-loop BGC texture operator outperforms the well-known LBP, and statistical significance of the achieved accuracy improvement has been demonstrated through the Wilkoxon signed rank test.

Journal ArticleDOI
TL;DR: In this article, the results of the investigation on the interactions between laser and arc plasma during laser-arc hybrid welding on magnesium alloy AZ31B using the spectral diagnose technique were presented.

Journal ArticleDOI
TL;DR: A new algorithm is proposed to search for the shortest branch cut length by simple exchange operation, on the basis of stochastic search techniques, which has a high probability of finding the shortest branches cut length or an approximation of it.

Journal ArticleDOI
TL;DR: In this paper, the authors presented the spatial evolution of the copper plume produced by the fundamental harmonic (1064) and second harmonic (532) of a Q-switched Nd:YAG laser.

Journal ArticleDOI
TL;DR: The system consists of projectors shooting the fringe patterns onto the inspected parts and cameras recording the corresponding distorted images, and the correspondence between the projector image and camera image can be established with sub-pixel accuracy.

Journal ArticleDOI
TL;DR: In this article, two zones of the laser irradiated area are defined: the distorted zone and the laser affected zone, and the parameters of the two zones are studied at different CO 2 laser beam sizes, irradiation times, and powers by microscopy, profilometry, and photoelastic method.

Journal ArticleDOI
TL;DR: A novel calibration method for MVS with non-overlapping fields of view based on 1D target that can be applied to vision sensors distributed in a large area or narrow space is presented.

Journal ArticleDOI
TL;DR: A variational level set-based curve evolution scheme that uses a significantly larger time step to numerically solve the evolution partial differential equation (PDE) for segmentation of an unideal iris image accurately, and thereby, speeding up the curve evolution process drastically.

Journal ArticleDOI
TL;DR: In this article, a two-frame interferometric method with a blind phase shift of a reference wave is proposed for the reconstruction of smooth surface relief areas, where a correlation approach based on the determination of correlation coefficient between intensity distributions of two interferograms is applied for the phase shift extraction.