Search results for "Resolution"
showing 10 items of 1928 documents
Time-resolved acousto-optic interaction in single-mode optical fibers: characterization of axial nonuniformities at the nanometer scale.
2014
We report on a time-resolved acousto-optic interaction technique for the detection of axial nonuniformities in single-mode fibers. It is based on the propagation of short packets of flexural acoustic waves. Small axial nonuniformities (of the order of nanometers) are detected by measuring the transmittance of the fundamental mode as a function of time. It is shown that the technique allows the detection of axial nonuniformities along sections of single-mode fiber exceeding 1 m long with spatial resolution of the order of a few centimeters.
Improvement of two-dimensional structured illumination microscopy with an incoherent illumination pattern of tunable frequency.
2018
In two-dimensional structured illumination microscopy (2D-SIM), high-resolution images with optimal optical sectioning (OS) cannot be obtained simultaneously. This tradeoff can be overcome by using a tunable-frequency 2D-SIM system and a proper reconstruction method. The goal of this work is twofold. First, we present a computational approach to reconstruct optical-sectioned images with super-resolution enhancement (OS-SR) by using a tunable SIM system. Second, we propose an incoherent tunable-frequency 2D-SIM system based on a Fresnel biprism implementation. Integration of the proposed computational method with this tunable structured illumination (SI) system results in a new 2D-SIM system…
A fast algorithm for muon track reconstruction and its application to the ANTARES neutrino telescope.
2011
An algorithm is presented, that provides a fast and robust reconstruction of neutrino induced upward-going muons and a discrimination of these events from downward-going atmospheric muon background in data collected by the ANTARES neutrino telescope. The algorithm consists of a hit merging and hit selection procedure followed by fitting steps for a track hypothesis and a point-like light source. It is particularly well-suited for real time applications such as online monitoring and fast triggering of optical follow-up observations for multi-messenger studies. The performance of the algorithm is evaluated with Monte Carlo simulations and various distributions are compared with that obtained …
Time calibration of the ANTARES neutrino telescope
2011
The ANTARES deep-sea neutrino telescope comprises a three-dimensional array of photomultipliers to detect the Cherenkov light induced by upgoing relativistic charged particles originating from neutrino interactions in the vicinity of the detector. The large scattering length of light in the deep sea facilitates an angular resolution of a few tenths of a degree for neutrino energies exceeding 10 TeV. In order to achieve this optimal performance, the time calibration procedures should ensure a relative time calibration between the photomultipliers at the level of ~1 ns. The methods developed to attain this level of precision are described.
Far-Field Optical Control of a Movable Subdiffraction Light Grid
2012
International audience; We demonstrate experimentally a subdiffraction light pattern, with a period down to 150 nm, at the surface of an optimized silicon nanostructured thin film. We show, using near-field and far-field characterization, that this subdiffraction pattern can be translated and rotated just by changing the illumination angle. The movable high frequency light pattern paves the way for subdiffraction resolution surface imaging microscopy without scanning near-field probes.
Scene-based spectral calibration assessment of high spectral resolution imaging spectrometers
2009
An accurate knowledge of the spectral calibration of imaging spectrometers is required for optimum data processing and interpretation. The scene-based spectral characterization of imaging spectrometers is frequently necessary to update or replace the pre-flight laboratory-based spectral characterization supplied by the data provider. An automatic method for the estimation of spectral calibration parameters (channel position and bandwidth) at atmospheric absorption regions from high spectral resolution imaging spectrometers (spectral sampling interval below 5 nm) is presented in this contribution. The method has been tested on two commercial instruments with spectral sampling intervals below…
In-situ time-resolved X-ray diffraction experiments applied to self-sustained reactions from mechanically activated mixtures
2000
Resume . Le procede MASHS (Mechanically activated self-propagating high-temperature synthesis) apparait etre un procede alternatif interessant pour elaborer des materiaux tels que des ceramiques, des composites ou des intermetalliques. La formation au cours d'une reaction de combustion autoentretenue d'intermetalliques, tels que NbAlj et M0S12, a ete suivie in-situ et en temps reel en couplant la diffraction des rayons X, produits par le rayonnement synchrotron (Ligne D43, LURE - Orsay) et, une thermographie infrarouge. A partir de temps d'acquisition tres courts (de 30 ms a 100ms par diffractogrammes), il a ete possible de determiner simultanement les evolutions structurales et thermiques.…
HIGH RESOLUTION STIMULATED RAMAN SPECTROSCOPY WITH A 3 MHz ACCURACY WAVEMETER
1987
THREE-DIMENSIONAL INTEGRAL MICROSCOPY WITH ENHANCED RESOLUTION AND DEPTH OF FIELD
2016
In this contribution we explain two new techniques developed by our group, which permit to increase the two-dimensional spatial resolution of the computed depth images in integral microscopy.