716 research outputs found

    First experimental demonstration of temporal hypertelescope operation with a laboratory prototype

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    In this paper, we report the first experimental demonstration of a Temporal HyperTelescope (THT). Our breadboard including 8 telescopes is firstly tested in a manual cophasing configuration on a 1D object. The Point Spread Function (PSF) is measured and exhibits a dynamics in the range of 300. A quantitative analysis of the potential biases demonstrates that this limitation is related to the residual phase fluctuation on each interferometric arm. Secondly, an unbalanced binary star is imaged demonstrating the imaging capability of THT. In addition, 2D PSF is recorded even if the telescope array is not optimized for this purpose.Comment: Accepted for publication in MNRAS. 11 pages, 25 figure

    Optical fiber systems are convectively unstable

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    We theoretically and experimentally evidence that fiber systems are convective systems since their nonlocal inherent properties, such as the dispersion and Raman effects, break the reflection symmetry. Theoretical analysis and numerical simulations carried out for a fiber ring cavity demonstrate that the third-order dispersion term leads to the appearance of convective and absolute instabilities. Their signature is an asymmetry in the output power spectrum. Using this criterion, experimental evidence of convective instabilities is given in a fiber cavity pumped by a pulsed laser

    Infection inapparente spontanée du Singe cynocéphale (Papio papio L.) au virus de Rubarth

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    Martin L.- A., Delage B. Infection inapparente spontanée du Singe cynocéphale (Papio papio L.) au virus de Rubarth. In: Bulletin de l'Académie Vétérinaire de France tome 108 n°6, 1955. pp. 225-228

    First test on Photonic Crystal Fiber potential for broadband interferometry

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    International audienceThe Photonic Crystal Fibers (PCFs) are microstructured waveguides currently developed in the frame of metrology, non-linear optics or coherent tomography. PCF studies are mainly focused on the improvement of dispersion property and wide spectral single-mode operating domain. Consequently, in the astronomical context, this kind of fiber is a good candidate to design a fiber linked version of stellar interferometer for aperture synthesis. In this paper, we study the potential of these fibers taking advantage of the wide spectral single-mode operation. We propose an experimental setup acting as a two-beam interferometer using PCFs to measure fringes contrasts at four different wavelengths (670nm, 980nm, 1328nm and 1543nm) corresponding to R, I, J and H astronomical bands with the same couple of PCFs. For this purpose, we implement for the first time a piezoelectric PCF optical path modulator

    Defect study of GaInP/GaAs based heterojunction bipolar transistor emitter layer

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    Defects in the emitter region of Ga0.51In0.49P/GaAs heterojunction bipolar transistors (HBTs) were investigated by means of deep-level transient spectroscopy. Both annealed (635 degreesC, 5 min) and as grown metalorganic chemical vapor deposition epitaxial wafers were investigated in this study, with an electron trap observed in the HBT emitter space-charge region from both wafers. The deep-level activation energy was determined to be 0.87+/-0.05 eV below the conduction band, the capture cross section 3x10(-14) cm(2) and the defect density of the order of 10(14) cm(-3). This defect was also found to be localized at the emitter-base interface

    EnquĂȘte sur l’infection du Chien au Maroc par le virus de Rubarth

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    Martin L.- A., Delage B., Hintermann J., Bellocq B. EnquĂȘte sur l’infection du Chien au Maroc par le virus de Rubarth. In: Bulletin de l'AcadĂ©mie VĂ©tĂ©rinaire de France tome 108 n°6, 1955. pp. 229-232

    EnquĂȘte sur l'infection naturelle du chien militaire au Maroc par le virus de Rubarth

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    Petrov Y.-J.-M., Delage B., Martin L.- A. EnquĂȘte sur l'infection naturelle du Chien militaire au Maroc par le virus de Rubarth. In: Bulletin de l'AcadĂ©mie VĂ©tĂ©rinaire de France tome 111 n°7, 1958. pp. 341-346

    Resonance Patterns of an Antidot Cluster: From Classical to Quantum Ballistics

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    We explain the experimentally observed Aharonov-Bohm (AB) resonance patterns of an antidot cluster by means of quantum and classical simulations and Feynman path integral theory. We demonstrate that the observed behavior of the AB period signals the crossover from a low B regime which can be understood in terms of electrons following classical orbits to an inherently quantum high B regime where this classical picture and semiclassical theories based on it do not apply.Comment: 5 pages revtex + 2 postscript figure
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