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Träfflista för sökning "L773:1094 4087 ;pers:(Svanberg Sune)"

Sökning: L773:1094 4087 > Svanberg Sune

  • Resultat 1-10 av 14
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1.
  • Abrahamsson, Christoffer, et al. (författare)
  • Time and wavelength resolved spectroscopy of turbid media using light continuum generated in a crystal fiber
  • 2004
  • Ingår i: Optics Express. - 1094-4087. ; 12:17, s. 4103-4112
  • Tidskriftsartikel (refereegranskat)abstract
    • We report a novel system for time-resolved diffuse remission spectral measurements, based on short light continuum pulses generated in an index-guided crystal fiber, and a spectrometer-equipped streak camera. The system enables spectral recordings of absorption and reduced scattering coefficients of turbid media in the wavelength range 500 - 1200 nm with a spectral resolution of 5 nm and a temporal resolution of 30 ps. The optical properties are calculated by fitting the solution of the diffusion equation to the time-dispersion curve at each wavelength. Example measurements are presented from an apple, a finger and a pharmaceutical tablet. (C) 2004 Optical Society of America.
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2.
  • Andersson, Mats, et al. (författare)
  • Spectroscopic studies of wood-drying processes
  • 2006
  • Ingår i: Optics Express. - 1094-4087. ; 14:8, s. 3641-3653
  • Tidskriftsartikel (refereegranskat)abstract
    • By the use of wavelength-modulation diode laser spectroscopy, water vapor and oxygen are detected in scattering media nonintrusively, at 980 nm and 760 nm, respectively. The technique demonstrated is based on the fact that free gases have extremely sharp absorption structures in comparison with the broad features of bulk material. Water vapor and oxygen measurements have been performed during the drying process of wood. The results suggest that the demonstrated technique can give information about the drying process of wood to complement that of commercially available moisture meters. In particular, the time when all the free water has evaporated from the wood can be readily identified by a strong falloff in the water vapor signal accompanied by the reaching of a high-level plateau in the molecular oxygen signal. Furthermore, the same point is identified in the differential optical absorption signal for liquid water, with a sharp increase by an order of magnitude in the ratio of the signal intensities at 980 nm and 760 nm.
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3.
  • Guan, Zuguang, et al. (författare)
  • Assessment of photon migration in scattering media using heterodyning techniques with a frequency modulated diode laser.
  • 2009
  • Ingår i: Optics Express. - 1094-4087. ; 17:18, s. 16291-16299
  • Tidskriftsartikel (refereegranskat)abstract
    • A novel technique for studying photon propagation in scattering media is proposed and demonstrated, as is believed, for the first time. Photons propagating through the medium, from a frequency-ramped single-mode diode laser, meet a reference beam from the same source, at a common detector, and beat frequencies corresponding to various temporal delays are observed by heterodyne techniques. Fourier transformation directly yields the temporal dispersion curve. Proof-of-principle experiments on polystyrene foam and a tissue phantom suggest, that the new method, when fully developed, may favorably compete with the more complex time-correlated single-photon counting (TCSPC) and the phase-shift methods, now much employed.
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4.
  • Guan, Zuguang, et al. (författare)
  • Quasi zero-background tunable diode laser absorption spectroscopy employing a balanced Michelson interferometer.
  • 2008
  • Ingår i: Optics Express. - 1094-4087. ; 16:26, s. 21714-21720
  • Tidskriftsartikel (refereegranskat)abstract
    • Tunable diode laser spectroscopy (TDLS) normally observes small fractional absorptive reductions in the light flux. We show, that instead a signal increase on a zero background can be obtained. A Michelson interferometer, which is initially balanced out in destructive interference, is perturbed by gas absorption in one of its arms. Both theoretical analysis and experimental demonstration show that the proposed zero-background TDLS can improve the achievable signal-to-noise ratio.
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5.
  • Lewander, Märta, et al. (författare)
  • Clinical system for non-invasive in situ monitoring of gases in the human paranasal sinuses
  • 2009
  • Ingår i: Optics Express. - 1094-4087. ; 17:13, s. 10849-10863
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a portable system for non-invasive, simultaneous sensing of molecular oxygen (O-2) and water vapor (H2O) in the human paranasal cavities. The system is based on high-resolution tunable diode laser spectroscopy (TDLAS) and digital wavelength modulation spectroscopy (dWMS). Since optical interference and non-ideal tuning of the diode lasers render signal processing complex, we focus on Fourier analysis of dWMS signals and procedures for removal of background signals. Clinical data are presented, and exhibit a significant improvement in signal-to-noise with respect to earlier work. The in situ detection limit, in terms of absorption fraction, is about 5 x 10(-5) for oxygen and 5 x 10(-4) for water vapor, but varies between patients due to differences in light attenuation. In addition, we discuss the use of water vapor as a reference in quantification of in situ oxygen concentration in detail. In particular, light propagation aspects are investigated by employing photon time-of-flight spectroscopy. (C) 2009 Optical Society of America
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6.
  • Lou, Xiutao, et al. (författare)
  • Detection of elemental mercury by multimode diode laser correlation spectroscopy
  • 2012
  • Ingår i: Optics Express. - 1094-4087. ; 20:5, s. 4927-4938
  • Tidskriftsartikel (refereegranskat)abstract
    • We demonstrate a method for elemental mercury detection based on correlation spectroscopy employing UV laser radiation generated by sum-frequency mixing of two visible multimode diode lasers. Resonance matching of the multimode UV laser is achieved in a wide wavelength range and with good tolerance for various operating conditions. Large mode-hops provide an off-resonance baseline, eliminating interferences from other gas species with broadband absorption. A sensitivity of 1 mu g/m(3) is obtained for a 1-m path length and 30-s integration time. The performance of the system shows promise for mercury monitoring in industrial applications.
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7.
  • Mei, Liang, et al. (författare)
  • Combined optical porosimetry and gas absorption spectroscopy in gas-filled porous media using diode-laser-based frequency domain photon migration
  • 2012
  • Ingår i: Optics Express. - 1094-4087. ; 20:15, s. 16942-16954
  • Tidskriftsartikel (refereegranskat)abstract
    • A combination method of frequency domain photon migration (FDPM) and gas in scattering media absorption spectroscopy (GASMAS) is used for assessment of the mean optical path length (MOPL) and the gas absorption in gas-filled porous media, respectively. Polystyrene (PS) foams, with extremely high physical porosity, are utilized as sample materials for proof-of-principle demonstration. The optical porosity, defined as the ratio between the path length through the pores and the path length through the medium, is evaluated in PS foam and found consistent with the measured physical porosity. The method was also utilized for the study of balsa and spruce wood samples.
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8.
  • Palombi, Lorenzo, et al. (författare)
  • Hyperspectral fluorescence lidar imaging at the Colosseum, Rome
  • 2008
  • Ingår i: Optics Express. - 1094-4087. ; 16:10, s. 6794-6808
  • Tidskriftsartikel (refereegranskat)abstract
    • Fluorescence lidar techniques offer considerable potential for remote, non-invasive diagnostics of stone cultural heritage in the outdoor environment. Here we present the results of a joint Italian-Swedish experiment, deploying two hyperspectral fluorescence lidar imaging systems, for the documentation of past conservation interventions on the Colosseum, Rome. Several portions of the monument were scanned and we show that it was possible to discriminate among masonry materials, reinforcement structures and protective coatings inserted during past conservation interventions, on the basis of their fluorescence signatures, providing useful information for a first quick, large-scale in situ screening of the monument.
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9.
  • Sandsten, Jonas, et al. (författare)
  • Gas visualization of industrial hydrocarbon emissions
  • 2004
  • Ingår i: Optics Express. - 1094-4087. ; 12:7, s. 1443-1451
  • Tidskriftsartikel (refereegranskat)abstract
    • Gases leaking from a polyethene plant and a cracker plant were visualized with the gas-correlation imaging technique. Ethene escaping from flares due to incomplete or erratic combustion was monitored. A leakage at a high-pressure reactor tank could be found and visualized by scanning the camera system over the industrial site. The image processing methods rely on the information from three simultaneously captured images. A direct and a gas-filtered infrared image are recorded with a split-mirror telescope through a joint band-pass filter. The resulting path-integrated gas concentration image, derived from the two infrared images, is combined with a visible image of the scene. The gas-correlation technique also has the potential to estimate the flux in the gas plume by combining a wind vector map, derived by cross-correlating the images in time, with a calibrated gas path-integrated concentration image. The principles of the technique are outlined and its potential discussed.
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10.
  • Sandsten, J, et al. (författare)
  • Real-time gas-correlation imaging employing thermal background radiation
  • 2000
  • Ingår i: Optics Express. - 1094-4087. ; 6:4, s. 92-103
  • Tidskriftsartikel (refereegranskat)abstract
    • Real-time imaging of gas leaks was demonstrated using an IR camera employing outdoor thermal background radiation. Ammonia, ethylene and methane detection was demonstrated in the spectral region 7-13 mu m. Imaging was accomplished using an optical filter and a gas-correlation cell matching the absorption band of the gas. When two gases, such as ammonia and ethylene, are absorbing in the same wavelength region it is possible to isolate one for display by using gas-correlation multispectral imaging. Results from a field test on a leaking gas tanker are presented as QuickTime movies. A detection limit of 200 ppm x meter for ammonia was accomplished in this setup when the temperature difference between the background and the gas was 18 K and the frame rate was 15 Hz. (C) 2000 Optical Society of America.
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