References of "Optics & Lasers in Engineering"
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See detail355nm UV laser patterning and post-processing of FR4 PCB for fine pitch components integration
Dupont, François ULiege; Stoukatch, Serguei ULiege; Laurent, Philippe ULiege et al

in Optics & Lasers in Engineering (2018), 100

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See detailAccuracy concerns in digital speckle photography combined with Fresnel digital holographic interferometry
Zhao, Yuchen ULiege; Zemmamouche, Redouane; Vandenrijt, Jean-François et al

in Optics & Lasers in Engineering (2017)

A combination of digital holographic interferometry (DHI) and digital speckle photography (DSP) allows in-plane and out-of-plane displacement measurement between two states of an object. The former can be ... [more ▼]

A combination of digital holographic interferometry (DHI) and digital speckle photography (DSP) allows in-plane and out-of-plane displacement measurement between two states of an object. The former can be determined by correlating the two speckle patterns whereas the latter is given by the phase difference obtained from DHI. We show that the amplitude of numerically reconstructed object wavefront obtained from Fresnel in-line digital holography (DH), in combination with phase shifting techniques, can be used as speckle patterns in DSP. The accuracy of in-plane measurement is improved after correcting the phase errors induced by reference wave during reconstruction process. Furthermore, unlike conventional imaging system, Fresnel DH offers the possibility to resize the pixel size of speckle patterns situated on the reconstruction plane under the same optical configuration simply by zero-padding the hologram. The flexibility of speckle size adjustment in Fresnel DH ensures the accuracy of estimation result using DSP. [less ▲]

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See detailAn in-line shearography setup based on circular polarization gratings
Blain, Pascal ULiege; Piron, Pierre ULiege; Renotte, Yvon ULiege et al

in Optics & Lasers in Engineering (2013)

The shearing amount defines the resolution of a speckle shearing interferometer and the shearing direction defines the sensitivity direction of the setup. The properties of circular (cycloid) holographic ... [more ▼]

The shearing amount defines the resolution of a speckle shearing interferometer and the shearing direction defines the sensitivity direction of the setup. The properties of circular (cycloid) holographic polarization gratings recorded in liquid crystal polymers can be used to build a new multi-shearing direction and amount shearography setup. The polarization states of the diffracted beams offer an easy way to produce phase shifts and thus to compute the phase contained in the shearograms. The theoretical bases of such a device are highlighted and an original compact and full in-line setup is proposed. First experimental results of delamination detection and flaw detection by shearography are presented. A discussion on the importance of the grating recording and the polarization orientation points out the best working requirements. [less ▲]

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See detailQuality assessment of speckle patterns for digital image correlation
Lecompte, D.; Smits, A.; Bossuyt, Sven et al

in Optics & Lasers in Engineering (2006), 44(11), 1132-1145

Digital image correlation (DIC) is an optical–numerical full-field displacement measuring technique, which is nowadays widely used in the domain of experimental mechanics. The technique is based on a ... [more ▼]

Digital image correlation (DIC) is an optical–numerical full-field displacement measuring technique, which is nowadays widely used in the domain of experimental mechanics. The technique is based on a comparison between pictures taken during loading of an object. For an optimal use of the method, the object of interest has to be covered with painted speckles. In the present paper, a comparison is made between three different speckle patterns originated by the same reference speckle pattern. A method is presented for the determination of the speckle size distribution of the speckle patterns, using image morphology. The images of the speckle patterns are numerically deformed based on a finite element simulation. Subsequently, the displacements are measured with DIC-software and compared to the imposed ones. It is shown that the size of the speckles combined with the size of the used pixel subset clearly influences the accuracy of the measured displacements. [less ▲]

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