76 research outputs found

    New multi-channel electron energy analyzer with cylindrically symmetrical electrostatic field

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    This paper discusses an electron energy analyzer with a cylindrically symmetrical electrostatic field, designed for rapid Auger analysis. The device was designed and built. The best parameters of the analyzer were estimated and then experimentally verified.Comment: 5 pages, 4 figure

    Tunable beam shaping with a phased array acousto-optic modulator

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    We demonstrate the generation of Bessel beams using an acousto-optic array based on a liquid filled cavity surrounded by a cylindrical multi-element ultrasound transducer array. Conversion of a Gaussian laser mode into a Bessel beam with tunable order and position is shown. Also higher-order Bessel beams up to the fourth order are successfully generated with experimental results very closely matching simulations

    Measuring Corporate Social Responsibility in tourism: Development and validation of an efficient measurement scale in the hospitality industry.

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    ABSTRAC: This article aims at developing an efficient measurement scale for corporate social responsibility in the tourism industry, given the contextual character that is recognized in the practice of this construct. Indicators were generated on the basis of a literature review and qualitative research. To assess the reliability and validity, first- and second-order confirmatory factor analysis were carried out. Results show a multidimensional structure of this construct—including economic, social, and environmental issues. This study contributes to the advancement of knowledge in the field of social responsibility through its practical application regarding concepts of sustainable development which have mainly been theoretical

    Speckle-scale focusing in the diffusive regime with time reversal of variance-encoded light (TROVE)

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    Focusing of light in the diffusive regime inside scattering media has long been considered impossible. Recently, this limitation has been overcome with time reversal of ultrasound-encoded light (TRUE), but the resolution of this approach is fundamentally limited by the large number of optical modes within the ultrasound focus. Here, we introduce a new approach, time reversal of variance-encoded light (TROVE), which demixes these spatial modes by variance encoding to break the resolution barrier imposed by the ultrasound. By encoding individual spatial modes inside the scattering sample with unique variances, we effectively uncouple the system resolution from the size of the ultrasound focus. This enables us to demonstrate optical focusing and imaging with diffuse light at an unprecedented, speckle-scale lateral resolution of ~5 µm

    An optical nanotrap array movable over a milimetre range

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    We present the theoretical and experimental study of nondiffracting Bessel beams as a device for optical manipulation and confinement of nanoparticles. We express analytically the optical forces acting on a nanoparticle placed into a single and two counter-propagating non-paraxial nondiffracting beams created behind the axicon. Nanoparticle behavior in these configurations is predicted by computer simulations. Finally we demonstrate experimentally how standing waves created from two independent counter-propagating nondiffraction beams confines polystyrene beads of radii 100 nm, and organizes them into a one-dimensional chain 1 mm long. Phase shift in one beam causes the motion of the whole structure of the standing wave together with any confined objects over its extent.</p

    An optical nanotrap array movable over a milimetre range

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    We present the theoretical and experimental study of nondiffracting Bessel beams as a device for optical manipulation and confinement of nanoparticles. We express analytically the optical forces acting on a nanoparticle placed into a single and two counter-propagating non-paraxial nondiffracting beams created behind the axicon. Nanoparticle behavior in these configurations is predicted by computer simulations. Finally we demonstrate experimentally how standing waves created from two independent counter-propagating nondiffraction beams confines polystyrene beads of radii 100 nm, and organizes them into a one-dimensional chain 1 mm long. Phase shift in one beam causes the motion of the whole structure of the standing wave together with any confined objects over its extent.</p

    Novel Super-Fast Three-Dimensional SEM Image Simulation

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    Sub-micron particle organization by self-imaging of non-diffracting beams

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    We present the first theoretical and experimental study of dielectric sub- micron particle behaviour in an optical field generated by interference of co- propagating non- diffracting beams of different propagation constants. In such a field, there are periodic oscillations of the on- axial intensity maxima ( self-imaging) that are frequently mentioned as useful for optical trapping. We show that in three dimensions this is true only for very small particles and the increasing number of interfering beams does not enable confinement of substantially bigger particles under the studied conditions. Experimentally, we succeeded in optical confinement of beads radii from 100 nm up to 300 nm but only with the help of fluid flow against the beams propagation. We observed self- organization of the particles into the periodic 1D array with the interparticle distance equal to 7.68 mu m. We observed how a bead jump from one trap to the neighbouring-occupied trap caused a domino effect propagating with constant velocity over the subsequent occupied traps. Phase shift in one beam induced controlled bi- directional shift of the whole structure over a maximal distance of 250 mu m in two co- propagating Bessel beams.</p
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