Search results for "Photon"

Noise reduction in asteroid imaging using a miniaturized spectral imager

2021

In October 2024, European Space Agency’s Hera mission will be launched, targeting the binary asteroid Didymos. Hera will host the Juventas and Milani CubeSats, the first CubeSats to orbit close to a small celestial body performing scientific and technological operations. The primary scientific payload of the Milani CubeSat is the SWIR, NIR, and VIS imaging spectrometer ASPECT. The Milani mission objectives include mapping the global composition and the characterization of the binary asteroid surface. Onboard data processing and evaluation steps will be applied due to the limited data budget for the downlink to Earth and to perform the technological demonstration of a novel semi-autonomous h…

Analysis of the $$\pi ^ + p$$ radiative scattering below the $$\Delta ^{ + + } \left( {1232} \right)$$ -resonance.

1981

Experimental Investigation of Fused Biconical Fiber Couplers for Measuring Refractive Index Changes in Aqueous Solutions

2016

A detailed experimental study of a simple and compact fiber optic sensor based on a fused biconical fiber coupler is presented, in which the sensitivity is improved by operating the coupler beyond the first coupling cycle. The sensor is demonstrated to perform high sensitivity measurements of refractive index changes by means of variation of sugar concentration in water. The device is operated to achieve a linear transmission response, allowing a linear relation between the sugar concentration and the output signal. The initial sensitivity was measured as 0.03 units of normalized transmission per unit of sugar concentration (g/100 mL), with a noise detection limit of a sugar concentration o…

Enhanced nanoscopy of individual CsPbBr3 perovskite nanocrystals using dielectric sub-micrometric antennas

2020

We demonstrate an efficient, simple, and low-cost approach for enhanced nanoscopy in individual green emitting perovskite (CsPbBr3) nanocrystals via TiO2 dielectric nanoantenna. The observed three- to five-fold emission enhancement is attributed to near-field effects and emission steering promoted by the coupling between the perovskite nanocrystals and the dielectric sub-micrometric antennas. The dark-field scattering configuration is then exploited for surface-enhanced absorption measurements, showing a large increase in detection sensitivity, leading to the detection of individual nanocrystals. Due to the broadband spectral response of the Mie sub-micrometric antennas, the method can be e…

Latest improvements of microchannel-plate PMTS

2020

Abstract The DIRC detectors of the PANDA experiment at FAIR will use multi-anode MCP-PMTs as photon sensors. After long and extensive R&D work the performance parameters of the recent 2” MCP-PMT models are converging towards the required values. The lifetime of most ALD-coated MCP-PMTs is well surpassing the DIRC requirements with the best tube currently reaching > 22 C/cm2 integrated anode charge without aging. The performance of the most advanced MCP-PMTs from PHOTONIS and Hamamatsu fulfill basically all requirements with a highlight being the high detective quantum efficiency (DQE) of almost 30% for the PHOTONIS 9002108. The improvements of the latest MCP-PMT models compared to former tu…

Multifunctional two-photon active silica-coated Au@MnO Janus particles for selective dual functionalization and imaging.

2014

Monodisperse multifunctional and nontoxic Au@MnO Janus particles with different sizes and morphologies were prepared by a seed-mediated nucleation and growth technique with precise control over domain sizes, surface functionalization, and dye labeling. The metal oxide domain could be coated selectively with a thin silica layer, leaving the metal domain untouched. In particular, size and morphology of the individual (metal and metal oxide) domains could be controlled by adjustment of the synthetic parameters. The SiO2 coating of the oxide domain allows biomolecule conjugation (e.g., antibodies, proteins) in a single step for converting the photoluminescent and superparamagnetic Janus nanopar…

3D and multispectral imaging for subcutaneous veins detection.

2009

The first and perhaps most important phase of a surgical procedure is the insertion of an intravenous (IV) catheter. Currently, this is performed manually by trained personnel. In some visions of future operating rooms, however, this process is to be replaced by an automated system. Experiments to determine the best NIR wavelengths to optimize vein contrast for physiological differences such as skin tone and/or the presence of hair on the arm or wrist surface are presented. For illumination our system is composed of a mercury arc lamp coupled to a 10nm band-pass spectrometer. A structured lighting system is also coupled to our multispectral system in order to provide 3D information of the p…

Multispectral integral imaging acquisition and processing using a monochrome camera and a liquid crystal tunable filter

2012

This paper presents an acquisition system and a procedure to capture 3D scenes in different spectral bands. The acquisition system is formed by a monochrome camera, and a Liquid Crystal Tunable Filter (LCTF) that allows to acquire images at different spectral bands in the [480, 680]nm wavelength interval. The Synthetic Aperture Integral Imaging acquisition technique is used to obtain the elemental images for each wavelength. These elemental images are used to computationally obtain the reconstruction planes of the 3D scene at different depth planes. The 3D profile of the acquired scene is also obtained using a minimization of the variance of the contribution of the elemental images at each …

Advanced endoscopic imaging for gastric cancer assessment: new insights with new optics?

2014

The most immediate strategy for improving survival of gastric cancer patients is secondary prevention through diagnosis of early gastric cancer either through screening or follow-up of individuals at high risk. Endoscopy examination is therefore of paramount importance and two general steps are to be known in assessing gastric mucosa - detection and characterization. Over the past decade, the advent of advanced endoscopic imaging technology led to diverse descriptions of these modalities reporting them to be useful in this setting. In this review, we aim at summarizing the current evidence on the use of advance imaging in individuals at high-risk (i.e., advance stages of gastric atrophy/int…

Thermodynamic approach of supercontinuum generation

2009

International audience; This paper is aimed at providing an overview on recent theoretical and experimental works in which a thermodynamic description of the incoherent regime of supercontinuum generation has been formulated. On the basis of the wave turbulence theory, we show that this highly nonlinear and quasi-continuous-wave regime of supercontinuum generation is characterized by two different phenomena. (i) A process of optical wave thermalization ruled by the four-wave mixing effects: The spectral broadening inherent to supercontinuum generation is shown to result from the natural tendency of the optical field to reach its thermodynamic equilibrium state, i. e., the state of maximum n…