Search results for "infrared"
showing 10 items of 2110 documents
Titanium Dioxide Waveguides for Data Transmissions at 1.55 µm and 1.98 µm
2017
International audience; We demonstrate error free transmissions of 10 Gbps signals in titanium dioxide waveguides at wavelengths of 1.55 or 2 µm. An efficient coupling of light is achieved thanks to metal grating couplers and we have checked that the component could be used with standard CWDM SFP+ devices.
Tunable source of infrared pulses in gas-filled hollow core capillary
2020
International audience; We report a tunable source that generates pulses in the infrared from an optical parametric amplification in a gas-filled hollow core capillary based on four-wave mixing process, in which the phase matching strongly depends on the gas pressure and the pump. In our case, we have generated pulses from 1 to 1.6 m in the sub-µJ level together with a parametric amplification in the visible.
Experimental and theoretical study of line mixing in methane spectra. III. The Q branch of the Raman nu(1) band
2000
International audience; The shape of the nu(1) Raman Q branch of CH4 perturbed by Ar and He at room temperature has been studied. Stimulated Raman spectroscopy (SRS) experiments have been made in the 2915-2918 cm(-1) spectral region for total pressures from 0.4 to 70 atm and mixtures of approximate to 5% CH4 with He and Ar. Analysis of the spectra demonstrates that the shape of the Q branch is significantly influenced by line mixing and much narrower than what is predicted by the addition of individual line profiles. For the first time, a model is proposed for the calculation and analysis of the effects of collisions on the considered spectra. In this approach, the rotational part of the re…
Hyperfine structure of some near-infrared Xe I and Xe II lines
2011
International audience; This work reports on the experimental determination of the hyperfine splitting of the Xe I lines at 828.01 nm and 834.68 nm and the Xe II line at 834.72 nm. Measurements were performed by means of Doppler-free saturation spectroscopy in a low-pressure radio-frequency discharge. The absolute wavelength of all hyperfine components is obtained by way of a high-precision wavemeter backed-up with the absorption spectrum of the NO 2 molecule. We provide an accurate estimate of hyperfine constants for the lower level of the Xe II transition at 834.72 nm. The two Xe I transition outcomes of our experimental study are compared with data available in the literature.
The 2016 CEOS Infrared Radiometer Comparison: Part II: Laboratory Comparison of Radiation Thermometers
2019
AbstractTo ensure confidence, measurements carried out by imaging radiometers mounted on satellites require robust validation using “fiducial quality” measurements of the same in situ parameter. For surface temperature measurements this is optimally carried out by radiometers measuring radiation emitted in the infrared region of the spectrum, collocated to that of a satellite overpass. For ocean surface temperatures the radiometers are usually on board ships to sample large areas but for land and ice they are typically deployed at defined geographical sites. It is of course critical that the validation measurements and associated instrumentation are internationally consistent and traceable …
EXO-PLANETARY HIGH-TEMPERATURE HYDROCARBONS BY EMISSION AND ABSORPTION SPECTROSCOPY (e-PYTHEAS PROJECT)
2019
International audience; e-PYTHEAS is a multidisciplinary project which combines theoretical and experimental work with exoplanet modelling applications. It sits on the frontier between molecular physics, theoretical chemistry and astrophysics. It aims at enhancing our understanding of the radiative properties of hot gaseous media to allow for improved analysis and interpretation of the large mass of data available on the thousands of exoplanets and exoplanetary systems known to date. Our approach is to use theoretical research validated by laboratory experiments and to then inject it into models of the atmospheres of the giant gaseous planets in the solar system and other planetary systems.…
Comparaison de deux méthodes de correction atmosphérique des données thermiques de Landsat TM
1996
The high resolution of Landsat Thematic Mapper (TM) thermal infrared data can be interesting in applications such as energy balance and crop water stress studies. However, surface temperature measurements are strongly affected by atmospheric effects, particularly by water vapour absorption, therefore a correction method is absolutely necessary. The impossibility of applying a split-window equation and the difficulty of having temporarily coincident radiosondes produce a slight use of Landsat TM data to obtain surface temperature. Vidal et al. show that in a zone with homogeneous climatic conditions, atmospheric correction can be evaluated by using energy balance equation and standard meteor…
Model, software, and database for line-mixing effects in the ν3 and ν4 bands of CH4 and tests using laboratory and planetary measurements. I. N2 (and…
2006
Absorption spectra of the infrared ν3 and ν4 bands of CH4 perturbed by N2 over large ranges of pressure and temperature have been measured in the laboratory. A theoretical approach accounting for line mixing is proposed to (successfully) model these experiments. It is similar to that of Pieroni et al. [J Chem Phys 1999;110:7717–32] and is based on state-to-state rotational cross-sections calculated with a semi-classical approach and a few empirical parameters. The latter, which enable switching from the state space to the line space, are deduced from a fit of a single room temperature spectrum of the ν3 band at 50 atm. The comparisons between numerous measured and calculated spectra under a…
The Mistigri Thermal Infrared Project: Scientific Objectives And Mission Specifications
2013
ISI Document Delivery No.: 147NI Times Cited: 4 Cited Reference Count: 117 Cited References: Abrams M, 2000, INT J REMOTE SENS, V21, P847, DOI 10.1080/014311600210326 Agam N, 2007, J GEOPHYS RES-ATMOS, V112, DOI 10.1029/2007JD008407 Allen RG, 2007, J IRRIG DRAIN E-ASCE, V133, P380, DOI 10.1061/(ASCE)0733-9437(2007)133:4(380) Alletto L, 2006, CHEMOSPHERE, V64, P1053, DOI 10.1016/j.chemosphere.2005.12.004 Arnfield AJ, 2003, INT J CLIMATOL, V23, P1, DOI 10.1002/joc.859 Baschek B., 2010, 2010 OC SCI M PORTL Bastiaanssen WGM, 1998, J HYDROL, V212, P198, DOI 10.1016/S0022-1694(98)00253-4 Bastiaanssen WGM, 2005, J IRRIG DRAIN E-ASCE, V131, P85, DOI 10.1061/(ASCE)0733-9437(2005)131:1(85) Beck LR, 2…
Response of soil bacterial communities to the incorporation of crop residues : influence of agricultural practices and link with the soil biological …
2010
The effect of the location of wheat residues (soil surface vs. incorporated in soil) on their decomposition and on soil bacterial communities was investigated by the means of a field experiment. Bacterial-Automated Ribosomal Intergenic Spacer Analysis (B-ARISA) of DNA extracts from residues, detritusphere (soil adjacent to residues), and bulk soil evidenced that residues constitute the zone of maximal changes in bacterial composition. However, the location of the residues influenced greatly their decomposition and the dynamics of the colonizing bacterial communities. Sequencing of 16S rRNA gene in DNA extracts from the residues at the early, middle, and late stages of degradation confirmed …