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  • 1.
    Alfredson, J.
    FOI, Swedish Defence Research Agency, P.O. Box 1165, SE-581 11 Linkoping, Sweden.
    Individual differences in visual behaviour in simulated flight2002In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4662, p. 494-502Conference paper (Other academic)
    Abstract [en]

    Flying an aircraft is highly visually demanding. It is very important to map pilot visual behaviour, both for the purpose of evaluating the cockpit interface and to effectively integrate it with future adaptive interfaces and decision support systems. Pilots' visual behaviour was studied in two experiments. In the first experiment commercial aviation pilots were flying a commercial aviation scenario and eye point of gaze, and eye blinks were collected. In the second experiment military pilots were flying an air-to-air combat scenario and the visual behaviour was video recorded. In both of the experiments the results show individual differences in the pilots' visual behaviour. In the second experiment two different categories of eye blinks were found that might help explain the individual differences in visual behaviour. One category can be related to the systematic eye blinks found to occur when the eye point of gaze was changed between head-up/head-down and head-down/head-up. The other category could be related to other reasons, such as, mental workload or visual demands.

  • 2.
    Andersson, I.
    et al.
    Saab Bofors Dynamics, S-581 88 Linkoping, Sweden.
    Haglund, L.
    Saab Bofors Dynamics, S-581 88 Linkoping, Sweden.
    Ronnqvist, E.
    Rönnqvist, E., Saab Bofors Dynamics, S-581 88 Linkoping, Sweden.
    Increasing spatial resolution by using an image sequence2001In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4380, p. 542-551Conference paper (Other academic)
    Abstract [en]

    In this paper we present two methods for increasing the spatial resolution of images using image sequences where all frames contain the same static scene with unknown shifts. Because of the subpixel shifts, aliased frequencies appear in a slightly different way in all images, making it possibly to reconstruct frequencies above the Nyqvist frequency, thus improving the resolution. To this end, we estimate parameters in the affine transform relating the images to each other from the sequence. To show the applicability of the algorithms, many experiments have been carried out mainly using image sequences captured by a TV-camera and not only using synthetic image sequences. The results from one TV-camera sequence are presented in this report. Measurements of PSF and MTF have been carried out and the results show that we can increase the spatial resolution by almost a factor of two. This technique can be used for target identification/recognition as well as for visualization. The second method (interpolation) is possible to implement in real time.

  • 3.
    Bjorstrom, Cecilia M.
    et al.
    Karlstad University.
    Nilsson, Svante
    Karlstad University.
    Magnusson, Kjell O.
    Karlstad University.
    Moons, Ellen
    Karlstad University.
    Bernasik, Andrzej
    AGH-Univ. of Science and Technology .
    Rysz, Jakub
    Jagiellonian Univ.
    Budkowski, Andrzej
    Jagiellonian Univ.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Andersson, Mats R.
    Chalmers.
    Influence of solvents and substrates on the morphology and the performance of low-bandgap polyfluorene: PCBM photovoltaic devices - art. no. 61921X2006In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6192, p. X1921-X1921Article in journal (Refereed)
    Abstract [en]

    Spin-coated thin films of poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-5,5-(4,7-di-2-thienyl-2,1,3-benzothiadiazole)] (APFO-3) blended with [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) are used as the active material in polymer photovoltaic cells. Such blends are known for their tendency to phase separate during film formation. Tuning the morphology of the blend in a controlled way is one possible road towards higher efficiency. We studied the effect of adding chlorobenzene to chloroform-based blend solutions before spin-coating on the conversion efficiency of APFO-3:PCBM photodiodes, and related that to the lateral and vertical morphology of thin films of the blend. The lateral morphology is imaged by atomic force microscopy (AFM) and the vertical compositional profile is obtained by dynamic secondary ion mass spectrometry (SIMS). The profiles reveal compositional variations consisting of multilayers of alternating polymer-rich and PCBM-rich domains in the blend film spin-coated from chloroform. The vertical compositional variations are caused by surface-directed spinodal waves and are frozen in during the rapid evaporation of a highly volatile solvent. With addition of the low-vapour pressure solvent chlorobenzene, a more homogeneous vertical composition is found. The conversion efficiency for solar cells of this blend was found to be optimal for chloroform: chlorobenzene mixtures with a volume-ratio of 80:1. We have also investigated the role of the substrate on the morphology. We found that blend films spin-coated from chloroform solutions on PEDOT:PSS-coated ITO show a similar compositional structure as the films on silicon, and that changing the substrate from silicon to gold only affects the vertical phase separation in a region close to the substrate interface.

  • 4.
    Elsharif Zainelabdin, Ahmed
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nur, Omer
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Amin, Gul
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Zaman, Siama
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Metal Oxide Nanostructures and White Light Emission2012In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 8263, no 82630NArticle in journal (Refereed)
    Abstract [en]

    We report on white light emission from zinc oxide nanostructures chemically grown on paper substrates. The effect of the growth solution pH on the morphology is discussed. The light emission form light emitting diodes based on ZnO nanorods/organic polymer hybrids on paper substrate is presented. Further copper oxide was grown on the walls of zinc oxide nanorods and the optical properties were investigated.

  • 5.
    Eriksson, Fredrik
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Johansson, G.A.
    Hertz, H.M.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Enhanced soft x-ray reflectivity of Cr/Sc multilayers by ion assisted sputter deposition2001In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4506, p. 84-92Conference paper (Other academic)
    Abstract [en]

    Cr/Sc multilayers have been grown on Si substrates using DC magnetron sputtering. The multilayers are intended as condenser mirrors in a soft x-ray microscope operating at the wavelength 3.374 nm. They were designed for normal reflection of the first and second order with multilayer periods of 1.692 nm and 3.381 nm, and layer thickness ratios of 0.471 and 0.237, respectively. At-wavelength soft x-ray reflectivity measurements were carried out using a reflectometer with a compact soft x-ray laser-plasma source. The multilayers were irradiated during growth with Ar ions, varying both in energy (9-113 eV) and flux, in order to stimulate the ad-atom mobility and improve the interface flatness. It was found that to obtain a maximum soft x-ray reflectivity with a low flux (Cr=0.76, Sc=2.5) of Ar ions a rather high energy of 53 eV was required. Such energy also caused intermixing of the layers. By the use of a solenoid surrounding the substrate, the arriving ion-to-metal flux ratio could be increased 10 times and the ion energy could be decreased. A high flux (Cr=7.1, Sc=23.1) of low energy (9 eV) Ar ions founded the most favourable growth condition in order to limit the intermixing with a subsistent surface flatness.

  • 6.
    Forssell, G.
    et al.
    Swedish Defence Research Agency, FOI, P.O. Box 1165, SE-581 11 LinkÖping, Sweden.
    Hedborg-Karlsson, E.
    Swedish Defence Research Agency, FOI, P.O. Box 1165, SE-581 11 LinkÖping, Sweden.
    Measurements of polarization properties of camouflaged objects and of the denial of surfaces covered with cenospheres2003In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 5075, p. 246-258Conference paper (Other academic)
    Abstract [en]

    Camouflaged objects in a background, which are not possible to observe with conventional IR measurements without polarization, can be seen in polarization measurements.. In this paper will be shown that polarization measurements increase the possibility to detect covered objects.The denial of polarization measurements of a covered object has earlier been achieved by construction of a surface covered with cenospheres. The emissivity as a function of angle of incidence has also been investigated on this newly developed surface, which can be designed to have emission properties decided in advance. The results indicate that it is possible to use the surface materiel as a means to adapt an object to a certain optical signature. It has also been shown that the surface almost completely depolarises the emitted radiation, which makes it more difficult to observe with a polarization measurement. These properties make the surface suitable as a reference surface for polarization measurements. A more systematic development of these surfaces and investigation are reported here.

  • 7.
    Fredriksson, Ingemar
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Absolute flow velocity components in laser Doppler flowmetry2006In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6094, p. 60940A-Article in journal (Refereed)
    Abstract [en]

    A method to separate a Doppler power spectrum into a number of flow velocity components, measured in absolute units (mm/s), is presented. A Monte Carlo software was developed to track each individual Doppler shift, to determine the probability, p(n), for a photon to undergo n Doppler shifts. Given this shift distribution, a mathematical relationship was developed and used to calculate a Doppler power spectrum originating from a certain combination of velocity components. The non linear Levenberg-Marquardt optimization method could thus be used to fit the calculated and measured Doppler power spectra, giving the true set of velocity components in the measured sample. The method was evaluated using a multi tube flow phantom perfused with either polystyrene microspheres or undiluted/diluted human blood (hct = 0.45). It estimated the velocity components in the flow phantom well, during both low and high concentrations of moving scatterers (microspheres or blood). Thus, further development of the method could prove to be a valuable clinical tool to differentiate capillary blood flow.

  • 8.
    Fridolin, Ivo
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Magnusson, M.
    Lindberg, Lars-Göran
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    Measurement of solutes in dialysate using UV absorption2001In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4263, p. 40-47Conference paper (Other academic)
    Abstract [en]

    The aim of this work was to describe a new method for optical monitoring of solutes in a spent dialysate. The method utilizes UV light absorption employing a commercially available spectrophotometer. Measurements were performed both on collected dialysate samples and on-line. The concentration of several removed solutes and electrolytes in the serum and in the dialysate was determined simultaneously using standard laboratory techniques. During on-line monitoring the spectrophotometer was connected to the fluid outlet of the dialysis machine. On-line measurements during a single hemodialysis session demonstrated a possibility to monitor deviations in the dialysator performance (e.g. dialysator in bypass). The experimental results indicated a good correlation between UV absorption and several removed solutes (urea, creatinine) in the spent dialysate. The correlation coefficient for urea and creatinine concentrations in the dialysate was very high for every individual treatment. The UV absorbance correlates well to the concentrations of several solutes thought to be uremic toxins. The results indicate that the technique can be used as a continuous, on-line method for monitoring deviations in the dialysator performance and may estimate the removal of the overall toxins. In the future, the new method will be used to evaluate parameters describing delivery of the prescribed treatment dose such as KT/V and Urea Reduction Rate (URR).

  • 9.
    Garbe, C.S.
    et al.
    Interdisc. Ctr. for Sci. Computing, University of Heidelberg, Heidelberg, Germany, Digital Image Processing, Interdisc. Ctr. for Sci. Computing, University of Heidelberg, Im Neuenheimer Feld 368, D-69120 Heidelberg, Germany.
    Spies, H.
    Jahne, B.
    Jähne, B., Interdisc. Ctr. for Sci. Computing, University of Heidelberg, Heidelberg, Germany.
    Estimation of complex motion from thermographic image sequences2003In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 5073, p. 303-317Conference paper (Other academic)
    Abstract [en]

    In this contribution a novel technique for computing complex motion involving heat transport processes will be presented. The proposed technique is a local gradient based approach, combining transport models with motion analysis. It allows for the simultaneous estimation of both motion and parameter of an underlying transport model. Since the analysis is based on thermal image sequences, estimates are computed to a high temporal and spatial resolution, limited only by the resolution and frame rate of the employed IR camera. This novel technique was utilized on exchange processes at the atmosphere/ocean boundary, where significant parameters of heat transfer could be measured and a transport model verified. Using the presented algorithms, surface flows as well as convergences and divergences on air-water interfaces can be measured accurately. Apart from applications in oceanography and botany, relevant benefits of the proposed technique to NDT will be presented. It is possible to compensate for motion to reach accuracies much better than 1/10th of a pixel. Through the direct estimation of locally resolved diffusivities in materials, insights can be gained about defects present. By estimating not only isotropic diffusion but also the whole matrix of anisotropic diffusion, the technique is highly relevant to measurements of composite materials.

  • 10.
    Haj-Hosseini, Neda
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Kistler, Benjamin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology. University of Applied Sciences in Northwest Switzerland.
    Wårdell, Karin
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Development and characterization of a brain tumor mimicking fluorescence phantom   2014In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 8945, p. 1-6, article id 894505Article in journal (Refereed)
    Abstract [en]

    Fluorescence guidance using 5-aminolevulinic acid (5-ALA) for brain tumor resection is a recent technique applied to the highly malignant brain tumors. Five-ALA accumulates as protoporphyrin IX fluorophore in the tumor cells in different concentrations depending on the tumor environment and cell properties. Our group has developed a fluorescence spectroscopy system used with a hand-held probe intra-operatively. The system has shown improvement of fluorescence detection and allows quantification that preliminarily correlates with tumor malignancy grade during surgery. However, quantification of fluorescence is affected by several factors including the initial fluorophore concentration, photobleaching due to operating lamps and attenuation from the blood. Accordingly, an optical phantom was developed to enable controlled fluorescence measurements and evaluation of the system outside of the surgical procedure. The phantom mimicked the optical properties of glioma at the specific fluorescence excitation wavelength when different concentrations of the fluorophore were included in the phantom. To allow evaluation of photobleaching, kinetics of fluorophore molecules in the phantom was restricted by solidifying the phantoms. Moreover, a model for tissue autofluorescence was added. The fluorescence intensity’s correlation with fluorophore concentration in addition to the photobleaching properties were investigated in the phantoms and were compared to the clinical data measured on the brain tumor.

  • 11.
    Johansson, Anders
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Physiological Measurements.
    A neural network for photoplethysmographic respiratory rate monitoring2001In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4434, p. 109-118Conference paper (Other academic)
    Abstract [en]

    The photoplethysmographic signal (PPG) includes respiratory components seen as frequency modulation of the heart rate (respiratory sinus arrhythmia, RSA), amplitude modulation of the cardiac pulse, and respiratory induced intensity variations (RIIV) in the PPG baseline. The aim of this study was to evaluate the accuracy of these components in determining respiratory rate, and to combine the components in a neural network for improved accuracy. The primary goal is to design a PPG ventilation monitoring system. PPG signals were recorded from 15 healthy subjects. From these signals, the systolic waveform, diastolic waveform, respiratory sinus arrhythmia, pulse amplitude and RIIV were extracted. By using simple algorithms, the rates of false positive and false negative detection of breaths were calculated for each of the five components in a separate analysis. Furthermore, a simple neural network (NN) was tried out in a combined pattern recognition approach. In the separate analysis, the error rates (sum of false positives and false negatives) ranged from 9.7% (pulse amplitude) to 14.5% (systolic waveform). The corresponding value of the NN analysis was 9.5-9.6%.

  • 12.
    Kanciurzewska, Anna
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Dobruchowska, Ewa
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Baranzahi, Amir
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Carlegrim, Elin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Ana
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Fahlman, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Girtu, Mihai A.
    Dye sensitized solar cells with a plastic counter electrode of poly(3,4-ethylene dioxythiophene)-poly(styrenesulfonate) - art. no. 6656112007In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6656, p. 65611-65611Article in journal (Refereed)
    Abstract [en]

    n/a

  • 13. Klasen, L.
    et al.
    Li, H.
    Forchheimer, Robert
    Linköping University, The Institute of Technology. Linköping University, Department of Electrical Engineering.
    Evaluation of a method for invariant and automated detection and tracking of objects from video2001In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4232, p. 455-463Conference paper (Other academic)
    Abstract [en]

    Video generates a rich set of image information and often the useful information is only a very limited set of the available information. Another well-known fact is that visually reviewing of long video recordings is a time demanding task. In combination with the continuously increasing number of video surveillance systems, this leads to an increasing need for automated analysis of long image sequences. The goal for this work is to develop and evaluate a method for automatic detection and tracking of events recorded onto a surveillance video, such as appearance of persons or vehicles in a surveyed area, to evaluate the usefulness for forensic applications and real time applications. One core problem is the fact that both the background and the objects move, where only the physical motion of moving objects are of interest and needs to be separated from the camera motion. Another core problem in many of the video processing algorithms is parameter estimation despite invariance for accurate modeling of the desired features. Varying scale, color, lightning conditions and occlusion of the object of interest can for example cause invariance. The technical approaches for this work is to separate global and local motion by analyzing the optical flow constraints. To overcome the problem caused by such feature and object invariance, all pixels are considered independently and no feature parameters are needed. If the basic optical flow constraint is satisfied, the motion is classified as global motion. If not, the motion is considered caused by local motion, noise or other phenomena. An object that undergoes local motion can then be detected and tracked as is forms a trace in the temporal domain, while the noise appears on an intermittent basis and will be disregarded. The results from applying this method on several image sequences were compared and the robustness and ability to deal with invariance has been evaluated. The result clearly shows that in realistic situations, where visual reviewing can be quite a difficult task, computer based methods for automatic detection are useful to detected moving objects in long video recordings.

  • 14.
    Leahy, M.J.
    et al.
    Department of Physics, University of Limerick, Limerick, Ireland.
    De, Mul F.F.M.
    De Mul, F.F.M., Department of Applied Physics, University of Twente, Enschede, Netherlands.
    Nilsson, G.E.
    Department of Biomedical Engineering, University of Linkoping, Linkoping, Sweden.
    Maniewski, R.
    Inst. of Biocybernet./Biomed. Eng., Warsaw, Poland.
    Liebert, A.
    Inst. of Biocybernet./Biomed. Eng., Warsaw, Poland.
    Developments in laser Doppler blood perfusion monitoring2002In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4876, no 1, p. 128-139Conference paper (Other academic)
    Abstract [en]

    This paper reviews the development and use of laser Doppler perfusion monitors and imagers. Despite their great success and almost universal applicability in microcirculation research, they have had great difficulty in converting to widespread clinical application. The enormous interest in microvascular blood perfusion coupled with the 'ease of use' of the technique has led to 2000+ publications citing its use. However, useful results can only be achieved with an understanding of the basic principles of the instrumentation and its application in the various clinical disciplines. The basic technical background is explored and definitions of blood perfusion and laser Doppler perfusion are established. The calibration method is then described together with potential routes to standardisation. A guide to the limitations in application of the technique gives the user a clear indication of what can be achieved in new studies as well as possible inadequacy in some published investigations. Finally some clinical applications have found acceptability and these will be explored.

  • 15.
    Lindbergh, Tobias
    et al.
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Larsson, Marcus
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Fredriksson, Ingemar
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Strömberg, Tomas
    Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation. Linköping University, The Institute of Technology.
    Reduced scattering coefficient determination by non-contact oblique angle illumination: methodological considerations2007In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6435, p. 64350I-1-64350I-12Article in journal (Refereed)
    Abstract [en]

    The reduced scattering coefficient, µs, was determined using oblique angle illumination and imaging backscattered light intensity. The distance r between the point of light incidence (hot-spot) and the circular symmetric diffuse reflectance centre, is ~1/µ. Previously, r was obtained analyzing a 1D strip aligned with the laser beam. We improved this method by calculating a 2D intensity image with extended dynamic range by assessing camera linearity, superimposing images with multiple integration times, and compensating for lens vignetting. The hot-spot algorithm utilises several images to minimize speckle variations and account for laser beam shape. Diffuse centre position is obtained by filtering the superimposed image with decreasing thresholds using momentum analysis to determine circular symmetry. The method was evaluated on 18 optical liquid phantoms with µs[1.5, 3.0] mm-1 and µs[0.01, 0.16] mm-1. The 2D method had better linearity with µs and smaller variations due to more stable hot-spot detection, than the 1D method. The anisotropy factor g was obtained by fitting measured and Monte Carlo simulated spatially resolved intensity decays and verified with a laser Doppler flowmetry technique. With an optimal compensation for the µa dependence, the rms error in µ estimation was 2.9%.

  • 16. Linderhed, A.
    et al.
    Lundberg, M.
    Department of Signals and System, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
    Nyberg, S.
    Sjokvist, S.
    Uppsall, M.
    Analysis of optical measurements on real minefields2002In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4742, no I, p. 160-171Conference paper (Other academic)
    Abstract [en]

    This paper presents preliminary analysis of the data from measurements on a minefield in Croatia done in the international cooperation project Airborne Minefield Area Reduction (ARC). Temperature differences above and around suspected mines and minefield indicators, were recorded with a long wave IR camera in 8-9 µm, over a time of several days, capturing data under different weather conditions. The data are compared to simulations of land mines, minefield indicators and other objects using a themodynamic FEM model, developed at FOI. Different detection methods are presented and applied to the data.

  • 17.
    Monemar, Bo
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Haratizadeh, H.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Kamiyama, S.
    Department of Electrical Engineering, Electron./High-Tech. Research Center, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468, Japan.
    Iwaya, M.
    Department of Electrical Engineering, Electron./High-Tech. Research Center, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468, Japan.
    Amano, H.
    Department of Electrical Engineering, Electron./High-Tech. Research Center, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468, Japan.
    Akasaki, I.
    Department of Electrical Engineering, Electron./High-Tech. Research Center, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468, Japan.
    Optical properties of InGaN/GaN and AlGaN/GaN multiple quantum well structures2003In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 5023, p. 63-67Conference paper (Other academic)
    Abstract [en]

    We report on low temperature photoluminescence (PL) in In xGa1-xN multiple quantum wells (MQWs) with x in the range 0.1 and highly Si doped barriers of In0.01Ga0.99N. One sample with 3 QWs of width 3.5 nm and barriers of width 10.5 nm had the MQW in the depletion region of the outer surface. Two PL peaks were observed, one QW exciton from the QW closest to the GaN buffer, one lower energy peak related to a 2DEG at the interface to the GaN buffer layer. In a second similar sample 5 QWs of width 3 nm and with 6 nm highly Si doped In0.01Ga 0.99N barriers the MQW was placed in the n-side depletion region of a pn-junction. At low temperatures the PL and electroluminescence (EL) spectra are quite different at no, low, or reverse bias, the PL appearing at higher energy. At high forward bias a spectral component at the EL position appears. This proves a strong influence of the depletion field on the optical spectra. Preliminary results are also reported for n-doped Al0.07Ga 0.93N/GaN structures, with near surface MQWs.

  • 18. Mukherjee, S.D.
    et al.
    Hadley, G.R.
    Sandia National Laboratories, MS 0603, PO Box 5800, Albuquerque, NM 87185, United States.
    Geib, K.M.
    Sandia National Laboratories, MS 0603, PO Box 5800, Albuquerque, NM 87185, United States.
    Choquette, K.D.
    Sandia National Laboratories, MS 0603, PO Box 5800, Albuquerque, NM 87185, United States, Dept of Electrical Engineering, University of Illinois, Urbana, IL 61801, United States.
    Carter, T.R.
    Sandia National Laboratories, MS 0603, PO Box 5800, Albuquerque, NM 87185, United States.
    Fischer, A.J.
    Sandia National Laboratories, MS 0603, PO Box 5800, Albuquerque, NM 87185, United States.
    Robinson, M.
    Schott Optovance, 15 Sandersdale Road, Southbridge, MA 01550, United States.
    Sullivan, C.T.
    Sandia National Laboratories, MS 0603, PO Box 5800, Albuquerque, NM 87185, United States.
    Critical parameters for parallel interconnects using VCSEL arrays and fiber image guides2002In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4942, p. 292-305Conference paper (Other academic)
    Abstract [en]

    Several thousand glass optical fibers fused together is routinely used as fiber image guides for medical and other image remoting applications. Fiber image guides also offer possibility for flexible optical interconnect links with potentially thousands of bi-directional parallel channels with data rates as high as 10 Gbps per channel, leading to more than Tera bits per second aggregate data transfer rates. A fair number of fiber image guide based link demonstrations using vertical cavity surface emitting lasers have been reported. However, little is known about designable parameters and optimization paradigms for applications to massively parallel optical interconnects. This paper discusses critical optical parameters that characterize a massively parallel link. Experimental characterizations were carried out to explore some of the fundamental interactions between single-mode 850 nm VCSELs and fiber image guides having different numerical apertures, 0.25, 0.55 and 1.00. Preliminary optical simulation results are given. Finally, potential directions for further experimental and analytical explorations, and for applicability into designable link systems are suggested.

  • 19.
    Pitois, C.
    et al.
    Royal Institute of Technology, Department of Polymer Technology, SE-10044 Stockholm, Sweden.
    Hult, A.
    Royal Institute of Technology, Department of Polymer Technology, SE-10044 Stockholm, Sweden.
    Lindgren, M.
    Swedish Defense Research Agency, Department of Laser Systems, SE-58111 Linkoping, Sweden.
    Characterization of fluorinated hyperbranched polymers and dendrimers for waveguide applications2002In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4805, p. 27-34Conference paper (Other academic)
    Abstract [en]

    We report on optical transmission properties and results of optical waveguide characterization of flourinated hyperbranched polymers and dendrimers (details on chemical synthesis were reported recently [1]). The polymers and dendrimers allow the introduction of additional functionality, such as cross-linking and refractive index tuneability. The dendrimers having a similar bulk structure as the hyperbranched polymer were also shown to house lanthanide cations for optical amplifying application. The fluorinated bulk structure results in a low contribution from vibration overtones in the absorption spectra in the NIR/IR region (800 - 2200 nm). The refractive index of the fundamental fluorinated hyperbranched polymer was found to be tuneable between ca 1.45 and 1.65 by incorporating various substituents. Optical losses were measured to be below ca 0.5 dB/cm at 1550 nm.

  • 20.
    Sethson, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Management and Engineering, Fluid and Mechanical Engineering Systems .
    Interactive Internet based pendulum for learning mechatronics2003In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 5018, p. 80-88Conference paper (Other academic)
    Abstract [en]

    This paper describes an Internet based remote experimental setup of a double linked pendulum mechanism for students experiments at the M. Sc. level. Some of the first year experience using this web-based setup in classes is referred. In most of the courses given at the division of mechanical engineering systems at Linköping Institute of Technology we provide experimental setups to enhance the teaching of M.Sc. students. Many of these experimental setups involve mechatronical systems. Disciplines like fluid power, electronics, and mechanics and also software technologies are used in each experiment. As our campus has recently been split into two different cities some new concepts for distance learning have been studied. The one described here tries to implement remotely controlled mechatronic setups for teaching basic programming of real-time operating systems and analysis of the dynamics of mechanical systems. The students control the regulators for the pendulum through a web interface and get measurement results and a movie back through their email. The present setup uses a double linked pendulum that is controlled by a DC-motor and monitored through both camera and angular position sensors. All software needed is hosted on a double-processor PC running the RedHat 7.1 distribution complemented with real-time scheduling using DIAPM-RTAI 1.7. The Internet site is presented to the students using PHP, Apache and MySQL. All of the used software originates from the open source domain. The experience from integrating these technologies and security issues is discussed together with the web-camera interface. One of the important experiences from this project so far is the need for a good visual feedback. This is both in terms of video speed but also in resolution. It has been noticed that when the students makes misstates and want to search the failure they want clear, large images with high resolution to support their personal believes in the cause of the failure. Even if the student does not need a high resolution image to get the idea of the mechanics and the function of the pendulum, they need such high quality images to get confidence in the hardware. It is important to support this when the ability to direct hand-on contact with the hardware is taken away. Some of the experiences in combining open source software, real-time scheduling and measurement hardware into a cost efficient way is also discussed. The pendulum has been available publicly on the Internet but has now been removed due to security issues.

  • 21.
    Soderberg, P.
    et al.
    Söderberg, P., St. Erik's Eye Hospital, Karolinska Institutet, SE 112 82 Stockholm, Sweden.
    Laurell, C.-G.
    St. Erik's Eye Hospital, Karolinska Institutet, SE 112 82 Stockholm, Sweden.
    Nordqvist, P.
    Skarman, E.
    Nordh, L.
    Virtual cataract surgery: Clinical evaluation2003In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4951, p. 62-66Conference paper (Other academic)
    Abstract [en]

    We have developed a simulator for phacoemulsification cataract extraction. In the current project, modules for clinical evaluation were developed. The system was structured into a processing computer and an administrator interface and a trainee interface. The simulation is defined by administrator adjustable parameters and trainee adjustable parameters. The parameters may be categorized as session characteristic parameters, patient characteristic parameters and trainee characteristic parameters. The simulation is measured in variables. Further an air bubble generator was created. We believe that simulator training in future will be required for becoming cataract surgeons.

  • 22.
    Starikov, Anton
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Yakimenko, I.I.
    Berggren, Karl-Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Graham, A.C.
    Cavendish Laboratory, Madingley Road, Cambridge CB3 00HE, United Kingdom.
    Thomas, K.J.
    Cavendish Laboratory, Madingley Road, Cambridge CB3 00HE, United Kingdom.
    Pepper, M.
    Cavendish Laboratory, Madingley Road, Cambridge CB3 00HE, United Kingdom.
    Simmons, M.Y.
    Cavendish Laboratory, Madingley Road, Cambridge CB3 00HE, United Kingdom.
    Effects of accidental microconstriction on the quantized conductance in long wires2003In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 5023, p. 267-270Conference paper (Other academic)
    Abstract [en]

    We have investigated the conductance of long quantum wires formed in GaAs/ AlxGa1-x As heterostructures. Using realistic fluctuation potentials from donor layers we have simulated numerically the conductance of four different kinds of wires. While ideal wires show perfect quantization, potential fluctuations from random donors may give rise to strong conductance oscillations and degradation of the quantization plateaux. Statistically there is always the possibility of having large fluctuations in a sample that may effectively act as a microconstriction. We therefore introduce microconstrictions in the wires by occasional clustering of donors. These microconstrictions are found to restore the quantized plateaux. A similar effect is found for accidental lithographic inaccuracies.

  • 23. Strifors, H.C.
    et al.
    Gaunaurd, G.C.
    U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783-1197, United States.
    Sullivan, A.
    U.S. Army Research Laboratory, 2800 Powder Mill Road, Adelphi, MD 20783-1197, United States.
    Reception and processing of electromagnetic pulses after propagation through dispersive and dissipative media2003In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 5094, p. 208-219Conference paper (Other academic)
    Abstract [en]

    Ultra-wideband ground penetrating radar (GPR) systems are useful for extracting and displaying information for target recognition purposes. The frequency content of projected signals is designed to match the size and type of prospective targets and environments. The soil medium is generally dispersive and, if moist, dissipative as well. Hence, target signatures whether in the time, frequency or joint time-frequency domains, will substantially depend on the target's burial depth, and on the soil's moisture content. To be useful for target recognition purposes the signatures of a given target must be known for several typical burial depths and soil moisture contents. These signatures are then used as templates in the classification process. In an attempt at reducing the number of needed templates, we focus here on the propagation of the pulses in the dissipative soil medium. Disregarding for the moment the scattering interaction with the target, we examine the distortion of the emitted interrogating pulses as they propagate through the soil and are back-scattered to the receiver. We simulated such returned target echoes earlier for several burial depths using a Method-of-Moments code. They all could then be translated to equivalent echoes from the target at some selected standardized depth and soil moisture, and vice-versa. A sufficiently accurate signal processing method for depth conversion could be employed to reduce the number of templates required for the correct classification of subsurface targets with a GPR.

  • 24.
    Wang, Q.
    et al.
    Optical Engineering Department, Acreo AB, Electrum 236, 164 40 Kista, Sweden.
    Junique, S.
    Optical Engineering Department, Acreo AB, Electrum 236, 164 40 Kista, Sweden.
    Agren, D.
    Ågren, D., Optical Engineering Department, Acreo AB, Electrum 236, 164 40 Kista, Sweden.
    Noharet, B.
    Optical Engineering Department, Acreo AB, Electrum 236, 164 40 Kista, Sweden.
    Malm, H.
    Optical Engineering Department, Acreo AB, Electrum 236, 164 40 Kista, Sweden.
    Borglind, J.
    Optical Engineering Department, Acreo AB, Electrum 236, 164 40 Kista, Sweden.
    Andersson, J.
    Optical Engineering Department, Acreo AB, Electrum 236, 164 40 Kista, Sweden.
    Sjoqvist, L.
    Ohgren, J.
    Wide-aperture GaAs/AlGaAs multiple quantum well electro-optic modulators2002In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4947, p. 59-67Conference paper (Other academic)
    Abstract [en]

    We present design and fabrication methods for surface normal monolithic amplitude modulators with an aperture up to 14 × 14 mm2, a contrast ratio of 6:1 and for low driving voltages (=8 V). The modulators consist of undoped GaAs/AlGaAs quantum wells embedded in a Fabry-Perot (FP) resonance cavity grown by MOVPE. To improve the device performance the FP cavity, the period and thickness of the quantum well and doping concentration were optimised. Also, the dimension of the modulator were varied from 0.5 × 0.5 to 14 × 14 mm2. The results show that the yield of the modulators increases significantly when decreasing the size of the modulators. To remedy the low yield issue for wide aperture modulator, a pixelated approach was used to divide the mono pixel in a monolithic modulator into several pixels, for example from 4 to 48. The modulation speed of the modulators with different dimensions was characterised by electro-optic (EO) response measurements. The temporal optical response of the large modulators was satisfactory up to the order of MHz modulation frequency where the RC constant limited the performance. A few of the modulators with wide apertures are to be assembled into an optical link system for free-space communication.

  • 25.
    Willander, Magnus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Lozovik, Y. E.
    Russian Academy of Sciences .
    Zhao, Q.X.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Nour, Omer
    Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Science and Technology.
    Hu, Q.-H.
    Gothenburg University.
    Klason, P.
    Gothenburg University.
    Excitonic effects in ZnO nanowires and hollow nanotubes2007In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 6486, no 648614Article in journal (Refereed)
    Abstract [en]

    Energy levels and wave functions of ground and excited states of an exciton are calculated by the method of imaginary time. Energy levels as functions of radius of single and double wall nanotube are studied. Asymptotic behavior of energy levels at large and small values of the radius using perturbation theory and adiabatic approximation is considered. Spatially indirect exciton in semiconductor nanowire is also investigated. Experimental result from high quality reproducible ZnO nanowires grown by low temperature chemical engineering is presented. State of the art high brightness white light emitting diodes (HB-LEDs) are demonstrated from the grown ZnO nano-wires. The color temperature and color rendering index (CRI) of the HB-LEDs values was found to be (3250 K, 82), and (14000 K, 93), for the best LEDs, which means that the quality of light is superior to one obtained from GaN LEDs available on the market today. The role of VZn and Vo on the emission responsible for the white light band as well as the peak position of this important wide band is thoroughly investigated in a systematic way.

  • 26.
    Wårdell, Karin
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Biomedical Engineering, Biomedical Instrumentation.
    Daniel, Karlsson M.G.
    Lonn, U.
    Traff, S.
    Casimir-Ahn, H.
    ECG-triggering of the laser Doppler signal - An approach for perfusion imaging on the beating calf heart2001In: Proceedings of SPIE, the International Society for Optical Engineering, ISSN 0277-786X, E-ISSN 1996-756X, Vol. 4254, p. 49-57Conference paper (Other academic)
    Abstract [en]

    Laser Doppler perfusion imaging (LDPI) has successfully been used to map the myocardial perfusion on patients undergoing coronary bypass surgery on the arrested heart. The need for intra-operative evaluation of graft function is obvious in routine surgery but even more imperative when adapting new surgical techniques where the procedure is performed on the beating heart. When using LDPI on the beating heart, artifacts originating from the movement of the heart are superimposed on the Doppler signal. We have investigated a method to reduce these artifacts by controlling the sampling sequence with ECG-triggering. The method has been assessed in an animal model on the beating calf heart. After sternotomy, an area covering 1 cm2 was imaged at the anterior wall of the left ventricle. In this area, six perfusion images were captured each of them recorded at fixed, but different time intervals in the cardiac cycle. In addition continuous measurements at one spot was done during 1-2 minutes. The signal recorded during pumping action was high compared to measurements performed in the same muscle area during infusion of blood with a syringe pump. Repeated measurements captured at a fixed delay time from the R-peak in the same areas at the same heart frequency showed reproducibility. ECG-triggering of the laser Doppler signal is the first step in our attempts to adapt LDPI to enabling assessment of myocardial perfusion on the beating heart. Further technical achievements and in-vivo investigations are, however, needed and will be performed by our research team in future studies.

1 - 26 of 26
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