Science.gov

Sample records for multi-wavelength images detector

  1. Multi-wavelength compressive computational ghost imaging

    NASA Astrophysics Data System (ADS)

    Welsh, Stephen S.; Edgar, Matthew P.; Jonathan, Phillip; Sun, Baoqing; Padgett, Miles J.

    2013-03-01

    The field of ghost imaging encompasses systems which can retrieve the spatial information of an object through correlated measurements of a projected light field, having spatial resolution, and the associated reflected or transmitted light intensity measured by a photodetector. By employing a digital light projector in a computational ghost imaging system with multiple spectrally filtered photodetectors we obtain high-quality multi-wavelength reconstructions of real macroscopic objects. We compare different reconstruction algorithms and reveal the use of compressive sensing techniques for achieving sub-Nyquist performance. Furthermore, we demonstrate the use of this technology in non-visible and fluorescence imaging applications.

  2. Up-conversion single-photon detector using multi-wavelength sampling techniques.

    PubMed

    Ma, Lijun; Bienfang, Joshua C; Slattery, Oliver; Tang, Xiao

    2011-03-14

    The maximum achievable data-rate of a quantum communication system can be critically limited by the efficiency and temporal resolution of the system's single-photon detectors. Frequency up-conversion technology can be used to increase detection efficiency for IR photons. In this paper we describe a scheme to improve the temporal resolution of an up-conversion single-photon detector using multi-wavelength optical-sampling techniques, allowing for increased transmission rates in single-photon communications systems. We experimentally demonstrate our approach with an up-conversion detector using two spectrally and temporally distinct pump pulses, and show that it allows for high-fidelity single-photon detection at twice the rate supported by a conventional single-pump up-conversion detector. We also discuss the limiting factors of this approach and identify important performance-limiting trade offs. PMID:21445185

  3. Touch the Invisible Sky: A multi-wavelength Braille book featuring NASA images

    NASA Astrophysics Data System (ADS)

    Steel, S.; Grice, N.; Daou, D.

    2008-06-01

    Multi-wavelength astronomy - the study of the Universe at wavelengths beyond the visible, has revolutionised our understanding and appreciation of the cosmos. Hubble, Chandra and Spitzer are examples of powerful, space-based telescopes that complement each other in their observations spanning the electromagnetic spectrum. While several Braille books on astronomical topics have been published, to this point, no printed material accessible to the sight disabled or Braille reading public has been available on the topic of multi-wavelength astronomy. Touch the Invisible Sky presents the first printed introduction to modern, multi-wavelength astronomy studies to the disabled sight community. On a more fundamental level, tactile images of a Universe that had, until recently, been invisible to all, sighted or non-sighted, is an important learning message on how science and technology broadens our senses and our understanding of the natural world.

  4. Hyperspectral fluorescence imaging with multi wavelength LED excitation

    NASA Astrophysics Data System (ADS)

    Luthman, A. Siri; Dumitru, Sebastian; Quirós-Gonzalez, Isabel; Bohndiek, Sarah E.

    2016-04-01

    Hyperspectral imaging (HSI) can combine morphological and molecular information, yielding potential for real-time and high throughput multiplexed fluorescent contrast agent imaging. Multiplexed readout from targets, such as cell surface receptors overexpressed in cancer cells, could improve both sensitivity and specificity of tumor identification. There remains, however, a need for compact and cost effective implementations of the technology. We have implemented a low-cost wide-field multiplexed fluorescence imaging system, which combines LED excitation at 590, 655 and 740 nm with a compact commercial solid state HSI system operating in the range 600 - 1000 nm. A key challenge for using reflectance-based HSI is the separation of contrast agent fluorescence from the reflectance of the excitation light. Here, we illustrate how it is possible to address this challenge in software, using two offline reflectance removal methods, prior to least-squares spectral unmixing. We made a quantitative comparison of the methods using data acquired from dilutions of contrast agents prepared in well-plates. We then established the capability of our HSI system for non-invasive in vivo fluorescence imaging in small animals using the optimal reflectance removal method. The HSI presented here enables quantitative unmixing of at least four fluorescent contrast agents (Alexa Fluor 610, 647, 700 and 750) simultaneously in living mice. A successful unmixing of the four fluorescent contrast agents was possible both using the pure contrast agents and with mixtures. The system could in principle also be applied to imaging of ex vivo tissue or intraoperative imaging in a clinical setting. These data suggest a promising approach for developing clinical applications of HSI based on multiplexed fluorescence contrast agent imaging.

  5. Multi-wavelength photoacoustic imaging of inducible tyrosinase reporter gene expression in xenograft tumors.

    PubMed

    Paproski, Robert J; Heinmiller, Andrew; Wachowicz, Keith; Zemp, Roger J

    2014-01-01

    Photoacoustic imaging is an emerging hybrid imaging technology capable of breaking through resolution limits of pure optical imaging technologies imposed by optical-scattering to provide fine-resolution optical contrast information in deep tissues. We demonstrate the ability of multi-wavelength photoacoustic imaging to estimate relative gene expression distributions using an inducible expression system and co-register images with hemoglobin oxygen saturation estimates and micro-ultrasound data. Tyrosinase, the rate-limiting enzyme in melanin production, is used as a reporter gene owing to its strong optical absorption and enzymatic amplification mechanism. Tetracycline-inducible melanin expression is turned on via doxycycline treatment in vivo. Serial multi-wavelength imaging reveals very low estimated melanin expression in tumors prior to doxycycline treatment or in tumors with no tyrosinase gene present, but strong signals after melanin induction in tumors tagged with the tyrosinase reporter. The combination of new inducible reporters and high-resolution photoacoustic and micro-ultrasound technology is poised to bring a new dimension to the study of gene expression in vivo. PMID:24936769

  6. Influence of color coatings on aircraft surface ice detection based on multi-wavelength imaging

    NASA Astrophysics Data System (ADS)

    Zhuge, Jing-chang; Yu, Zhi-jing; Gao, Jian-shu; Zheng, Da-chuan

    2016-03-01

    In this paper, a simple aircraft surface ice detection system is proposed based on multi-wavelength imaging. Its feasibility is proved by the experimental results. The influence of color coatings of aircraft surface is investigated. The results show that the ice area can be clearly distinguished from the red, white, gray and blue coatings painted aluminum plates. Due to the strong absorption, not enough signals can be detected for the black coatings. Thus, a deep research is needed. Even though, the results of this paper are helpful to the development of aircraft surface ice detection.

  7. Detector Having A Transmission Grating Beam Splitter For Multi-Wavelength Sample Analysis.

    DOEpatents

    Liu, Changsheng; Li, Qingbo

    2000-09-12

    A detector for DNA sample identification is provided with a transmission grating beam splitter (TGBS). The TGBS split fluoresced light from a tagged DNA sample into 0th order and a 1st order components, both of which are detected on a two-dimensional detector array of a CCD camera. The 0th and 1st order components are detected along a column of pixels in the detector array, and are spaced apart from one another. The DNA samples are tagged with four fluorescent dyes, one dye specific for each nucleotide, and all four dyes responding in slightly different manner to the same monochromatic excitation signal. The TGBS splits fluoresced incoming light into 0th and 1st order components, which are then spread out among a number of pixels in the detector array. The 1st component of this light is received by pixels whose position relative to the 0th order component depends on the frequency of fluorescence. Thus, the position at which signal energy is detected on the array is indicative of the particular dye, and therefore, the corresponding nucleotide tagged by that dye. Monitoring signal energy at the 0th order pixel and selected 1st order pixels, provides a set of data from which one may then identify the particular nucleotide.

  8. Detector Having A Transmission Grating Beam Splitter For Multi-Wavelength.

    DOEpatents

    Liu, Changsheng; Li, Qingbo (State College, PA

    1999-12-07

    A detector for DNA sample identification is provided with a transmission grating beam splitter (TGBS). The TGBS split fluoresced light from a tagged DNA sample into 0th order and a 1st order components, both of which are detected on a two-dimensional detector array of a CCD camera. The 0th and 1st order components are detected along a column of pixels in the detector array, and are spaced apart from one another. The DNA samples are tagged with four fluorescent dyes, one dye specific for each nucleotide, and all four dyes responding in slightly different manner to the same monochromatic excitation signal. The TGBS splits fluoresced incoming light into 0th and 1st order components, which are then spread out among a number of pixels in the detector array. The 1st component of this light is received by pixels whose position relative to the 0th order component depends on the frequency of fluorescence. Thus, the position at which signal energy is detected on the array is indicative of the particular dye, and therefore, the corresponding nucleotide tagged by that dye. Monitoring signal energy at the 0th order pixel and selected 1st order pixels, provides a set of data from which one may then identify the particular nucleotide.

  9. A compact, multi-wavelength, and high frequency response light source for diffuse optical spectroscopy and imaging

    NASA Astrophysics Data System (ADS)

    Park, Kyoungsu; Lee, Minseok; Lee, Seung-ha; Cerussi, Albert E.; Chung, Phil-sang; Kim, Sehwan

    2015-03-01

    Many biomedical applications require an efficient combination and localization of multiple discrete light sources. In this paper, we present a compact six-channel combiner of optical sub-assembly type that couples the output of independent solid-state light sources into a single 400 μm diameter optical fiber. It is equipped with six discrete laser diodes, 658, 690, 705, 785, 830, and 850 nm for the measurement of the tissue optical properties from optical spectroscopy and imaging. We demonstrate coupling efficiencies ≥ 77% and output optical power ≥ 20 mW for each of the 6 laser diodes installed into the prototype. The design supports the use of continuous wave and intensity modulated laser diodes (with bandwidth ≥ 3 GHz). The developed light source could be used to construct custom multi-wavelength sources for tissue oximeters, diffuse optical imaging, and molecular imaging technologies.

  10. Integral field spectroscopy and multi-wavelength imaging of the nearby spiral galaxy NGC 5668: a case for MEGARA

    NASA Astrophysics Data System (ADS)

    Marino, R. A.; Gil de Paz, A.; Castillo-Morales, A.; Muñoz-Mateos, J. C.; Sánchez, S. F.; Pérez-González, P. G.; Gallego, J.; Zamorano, J.; Alonso-Herrero, A.; Boissier, S.

    2013-05-01

    In order to improve our understanding of the mechanisms that drive the evolution of disk galaxies we analyze the full bi-dimensional spectral cube of the nearby spiral galaxy NGC 5668, which was obtained as a mosaic of 6 pointings, covering a total area of 2 × 3 arcmin^{2}, obtained with the PPAK Integral Field Unit at the Calar Alto (CAHA) observatory 3.5 m telescope. From these data we obtain the bidimensional spatial distribution maps of the attenuation of the ionized gas, and chemical abundances of oxygen. We find a mean ionized-gas attenuation of A_V˜1 mag, with the gas attenuation appearing larger than the continuum attenuation by a factor of 3. With respect to the oxygen abundance, we find that, while inwards of r ˜36''˜ 4.4kpc ˜ 0.36 ({D_{25}}/{2}) the derived O/H ratio follows the radial gradient typical of the disks of spiral galaxies, the abundance gradient beyond r˜36'' flattens out. The multi-wavelength surface brightness profiles of NGC 5668 are compared with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks in the context of the inside-out scenario of disk formation. Both the deviations of the color profiles and the shape of the metallicity radial distribution indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC5668 beyond what is predicted by the inside-out scenario. This study demonstrates the strength of the combination of IFU and multi-wavelength imaging data. With MEGARA, the future optical IFU & MOS for 10.4-m GTC we will fill the gap currently existing in astronomical instrumentation with high spectral resolution and large area coverage simultaneously addressing such fundamental issues in galactic structure and evolution.

  11. New Hubble Space Telescope Multi-Wavelength Imaging of the Eagle Nebula

    NASA Astrophysics Data System (ADS)

    Levay, Zoltan G.; Christian, Carol A.; Mack, Jennifer; Frattare, Lisa M.; Livio, Mario; Meyett, Michele L.; Mutchler, Maximilian J.; Noll, Keith S.; Hubble Heritage

    2015-01-01

    One of the most iconic images from the Hubble Space Telescope has been the 1995 WFPC2 image of the Eagle Nebula (M16, sometimes known as the "Pillars of Creation"). Nineteen years after those original observations, new images have been obtained with HST's current instrumentation: a small mosaic in visible-light, narrow-band filters with WFC3/UVIS, infrared, broad-band filters with WFC3/IR, and parallel Hα imaging with ACS/WFC. The wider field of view, higher resolution, and broader wavelength coverage of the new images highlight the improved capabilities of HST over its long-lasting operation, made possible by the upgraded instrumentation installed during Space Shuttle servicing missions. Csite images from these datasets are presented to commemorate the 25th anniversary of HST's launch. Carefully combined, aligned and calibrated datasets from the primary WFC3 fields are available as High-Level Science Products in MAST (http://archive.stsci.edu/prepds/heritage/). Color composite images from these datasets are presented to commemorate the 25th anniversary of HST's launch.

  12. HST/WFC3 Imaging and Multi-Wavelength Characterization of Edge-On Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Gould, Carolina; Duchene, Gaspard; Stapelfeldt, Karl R.; Menard, Francois; Padgett, Deborah; Perrin, Marshall D.; Pinte, Christophe; Wolff, Schuyler

    2016-06-01

    Edge-on views of protoplanetary disk systems provide a unique observing opportunity to assess the vertical dust structure of the disk, an opportunity that is not possible at any other viewing angle due to projection effects and the acute brightness of the central star. Comparing high-resolution scattered light images of edge-on disks with synthetic images from radiative transfer modeling is a powerful approach to constrain the disk mass, structure and dust content, although analyses based on single-wavelength images lead to ambiguous conclusions. In order to resolve these ambiguities, and to probe the most tenuous regions at high elevation above the disk midplane, it is critical to obtain high-resolution images of such objects at the shortest possible wavelengths, where dust opacity is maximized. In this contribution, we present new WFC3 F475W Hubble Space Telescope images of 6 known edge-on protoplanetary disks. We produced color maps across the visible band to identify and characterize wavelength-dependent properties of these disks. In turn, these allow us to differentiate features that are related to the dust properties (opacity, scattering phase function) from those tracing the physical structure of the disk (in particular its vertical density profile). By probing a diverse set of disks with a uniform approach, we will be able to probe possible signs of evolution in this critical stage of planet formation.

  13. Single camera system for multi-wavelength fluorescent imaging in the heart.

    PubMed

    Yamanaka, Takeshi; Arafune, Tatsuhiko; Shibata, Nitaro; Honjo, Haruo; Kamiya, Kaichiro; Kodama, Itsuo; Sakuma, Ichiro

    2012-01-01

    Optical mapping has been a powerful method to measure the cardiac electrophysiological phenomenon such as membrane potential(V(m)), intracellular calcium(Ca(2+)), and the other electrophysiological parameters. To measure two parameters simultaneously, the dual mapping system using two cameras is often used. However, the method to measure more than three parameters does not exist. To exploit the full potential of fluorescence imaging, an innovative method to measure multiple, more than three parameters is needed. In this study, we present a new optical mapping system which records multiple parameters using a single camera. Our system consists of one camera, custom-made optical lens units, and a custom-made filter wheel. The optical lens units is designed to focus the fluorescence light at filter position, and form an image on camera's sensor. To obtain optical signals with high quality, efficiency of light collection was carefully discussed in designing the optical system. The developed optical system has object space numerical aperture(NA) 0.1, and image space NA 0.23. The filter wheel was rotated by a motor, which allows filter switching corresponding with needed fluorescence wavelength. The camera exposure and filter switching were synchronized by phase locked loop, which allow this system to record multiple fluorescent signals frame by frame alternately. To validate the performance of this system, we performed experiments to observe V(m) and Ca(2+) dynamics simultaneously (frame rate: 125fps) with Langendorff perfused rabbit heart. Firstly, we applied basic stimuli to the heart base (cycle length: 500ms), and observed planer wave. The waveforms of V(m) and Ca(2+) show the same upstroke synchronized with cycle length of pacing. In addition, we recorded V(m) and Ca(2+) signals during ventricular fibrillation induced by burst pacing. According to these experiments, we showed the efficacy and availability of our method for cardiac electrophysiological research. PMID

  14. Multi-wavelength imaging of the peculiar Vela Molecular Ridge nebula BBW 192E

    NASA Astrophysics Data System (ADS)

    Burkert, A.; Stecklum, B.; Henning, Th.; Fischer, O.

    2000-01-01

    We present the first images of the nebula BBW 192E at near- and mid-infrared wavelengths as well as a 1.3 mm continuum map. The nebula BBW 192E is associated with the IRAS point source 08513-4201 which has a luminosity of about 1400 L_sun and a strongly rising spectral energy distribution towards mid-infrared wavelengths. The infrared images show a pronounced bipolar nebula, which is offset by about 10arcsec from the known optical emission, as well as several point sources. We interpret this morphology as evidence for an inclined disk-like structure and scattered light emerging from the lobes. This is supported by our near-infrared imaging polarimetry at sub-arcsecond resolution which furthermore indicates that the central energy source is seen directly at near-infrared wavelengths. At 1.3 millimetre, we detected a cometary shaped source in the dust continuum radiation, 151arcsec x 55arcsec in size, with a total mass of 180 M_sun as well as average hydrogen column and number densities of 4.5x1022 cm-2 and 2.6x105 cm-3, respectively. This dust cloud is also responsible for the strong spatial variation of the extinction across the nebula. We discuss the physical properties of the infrared point sources and conclude that some might be young, low-mass pre-main sequence stars. The main energy source of the nebula is an embedded intermediate-mass young stellar object. These observations are among the first infrared detections of a disk-like system associated with a bipolar nebula surrounding an intermediate-mass young stellar object. Based on observations collected at the European Southern Observatory, La Silla, Chile (Proposal-IDs: 57.B-0392, 52.7-0086, 57.D-0260, 58.D-0213, and 63.I-0173)

  15. A Multi-Wavelength Optical Imaging Study of a Unique Star-Forming Environment: Polar Rings

    NASA Astrophysics Data System (ADS)

    Aller, Monique C.; Kulkarni, Varsha P.; Higdon, James L.; Higdon, Sarah J. U.

    2012-02-01

    In order to fully understand galaxy formation and evolution, it is essential to understand the star-formation (SF) processes occurring within galaxies. This requires studying not only SF in galaxies of regular morphology, but also locally-uncommon SF processes occurring within structures formed through mergers or accretion, which may be more prevalent at high-redshift. Polar ring galaxies (PRGs), which consist of a robustly star-forming ring of gas, dust, and stars orbiting in a plane perpendicular to the major axis of a central, host galaxy, provide such a unique SF environment. It has been hypothesized that stochastic processes, such as supernova shock propagation, stimulate the SF within the polar ring (PR). We propose to obtain Gemini GMOS imaging of 10 PRGs to trace the young stellar population in these structures. Combining these data with our existing Spitzer IRAC 3.6 and 4.5 micron data, and archival UV and HI maps, we will examine: (1) the stellar population, masses, and ages, as a function of spatial position, in the PRGs and their host galaxies; (2) the SF triggering mechanisms and gravitational stability in PRs; and (3) the opacity of the dust in PRs. We will also (4) place structural constraints on proposed PR formation mechanisms.

  16. Multi-wavelength imaging of the peculiar VELA Molecular Rigde nebula BBW 192E

    NASA Astrophysics Data System (ADS)

    Burkert, A.; Henning, Th.; Fischer, O.; Stecklum, B.

    We present new imaging data on the nebula BBW 192E at near- and mid-infrared wavelengths as well as a 1.3 mm continuum map. We detected a cometary shaped millimetre emission in an area of 151'' x 55'' size with a total mass of 177 M_\\odot. At infrared wavelengths several point sources and a pronounced bipolar nebula which is offset by about 10'' of the main optical emission were detected. We discuss the physical properties of the point sources and show that some might be young, intermediate-mass stars. Finally, we give an interpretation of the morphologies observed at different wavelengths caused by a molecular cloud, a nearly edge-on seen disk as well as an outflow. We interpret the observed bipolar morphology as evidence for a disk object which is still embedded within the parental cloud. According to the high luminosity (~ 1400 L_{\\odot}) and the infrared morphology of BBW 192E we propose that a Herbig Ae/Be binary or Herbig Ae/Be -- T Tauri system is located in the centre of the bipolar infrared nebula. Another possibility is that we see the outflow cone of a disk-like structure.

  17. Position-sensitive multi-wavelength photon detectors based on epitaxial InGaAs/InAlAs quantum wells

    NASA Astrophysics Data System (ADS)

    Ganbold, T.; Antonelli, M.; Cautero, G.; Menk, R. H.; Cucini, R.; Biasiol, G.

    2015-09-01

    Beam monitoring in synchrotron radiation or free electron laser facilities is extremely important for calibration and diagnostic issues. Here we propose an in-situ detector showing fast response and homogeneity for both diagnostics and calibration purposes. The devices are based on In0.75Ga0.25As/In0.75Al0.25As QWs, which offer several advantages due to their direct, low-energy band gap and high electron mobility at room temperature. A pixelation structure with 4 quadrants was developed on the back surface of the device, in order to fit commercially available readout chips. The QW devices have been tested with collimated monochromatic X-ray beams from synchrotron radiation. A rise in the current noise with positive bias was observed, which could be due to deep traps for hole carriers. Therefore, an optimized negative bias was chosen to minimize dark currents and noise. A decrease in charge collection efficiency was experienced as the beam penetrates into deeper layers, where a dislocation network is present. The prototype samples showed that individual currents obtained from each quadrant allow the position of the beam to be monitored for all the utilized energies. These detectors have a potential to estimate the position of the beam with a precision of about 10 μm.

  18. Multi-wavelength fluorescence tomography

    NASA Astrophysics Data System (ADS)

    Kwong, Tiffany C.; Lo, Pei-An; Cho, Jaedu; Nouizi, Farouk; Chiang, Huihua K.; Kim, Chang-Seok; Gulsen, Gultekin

    2016-03-01

    The strong scattering and absorption of light in biological tissue makes it challenging to model the propagation of light, especially in deep tissue. This is especially true in fluorescent tomography, which aims to recover the internal fluorescence source distribution from the measured light intensities on the surface of the tissue. The inherently ill-posed and underdetermined nature of the inverse problem along with strong tissue scattering makes Fluorescence Tomography (FT) extremely challenging. Previously, multispectral detection fluorescent tomography (FT) has been shown to improve the image quality of FT by incorporating the spectral filtering of biological tissue to provide depth information to overcome the inherent absorption and scattering limitations. We investigate whether multi-wavelength fluorescent tomography can be used to distinguish the signals from multiple fluorophores with overlapping fluorescence spectrums using a unique near-infrared (NIR) swept laser. In this work, a small feasibility study was performed to see whether multi-wavelength FT can be used to detect subtle shifts in the absorption spectrum due to differences in fluorophore microenvironment.

  19. High-performance size exclusion chromatography with a multi-wavelength absorbance detector study on dissolved organic matter characterisation along a water distribution system.

    PubMed

    Huang, Huiping; Sawade, Emma; Cook, David; Chow, Christopher W K; Drikas, Mary; Jin, Bo

    2016-06-01

    This study examined the associations between dissolved organic matter (DOM) characteristics and potential nitrification occurrence in the presence of chloramine along a drinking water distribution system. High-performance size exclusion chromatography (HPSEC) coupled with a multiple wavelength detector (200-280nm) was employed to characterise DOM by molecular weight distribution, bacterial activity was analysed using flow cytometry, and a package of simple analytical tools, such as dissolved organic carbon, absorbance at 254nm, nitrate, nitrite, ammonia and total disinfectant residual were also applied and their applicability to indicate water quality changes in distribution systems were also evaluated. Results showed that multi-wavelength HPSEC analysis was useful to provide information about DOM character while changes in molecule weight profiles at wavelengths less than 230nm were also able to be related to other water quality parameters. Correct selection of the UV wavelengths can be an important factor for providing appropriate indicators associated with different DOM compositions. DOM molecular weight in the range of 0.2-0.5kDa measured at 210nm correlated positively with oxidised nitrogen concentration (r=0.99), and the concentrations of active bacterial cells in the distribution system (r=0.85). Our study also showed that the changes of DOM character and bacterial cells were significant in those sampling points that had decreases in total disinfectant residual. HPSEC-UV measured at 210nm and flow cytometry can detect the changes of low molecular weight of DOM and bacterial levels, respectively, when nitrification occurred within the chloraminated distribution system. PMID:27266320

  20. Multi-wavelength holographic profilometry

    NASA Astrophysics Data System (ADS)

    Barbosa, E. A.; Gesualdi, M. R.; Muramatsu, M.

    2006-01-01

    A novel method for surface profilometry by holography is presented. We used a diode laser emitting at many wavelengths simultaneously as the light source and a Bi 12TiO 20 (BTO) crystal as the holographic medium in single exposure processes. The employ of multi-wavelength, large free spectral range (FSR) lasers leads to holographic images covered of interference fringes corresponding to the contour lines of the studied surface. In order to obtain the relief of the studied surface, the fringe analysis was performed by the phase stepping technique (PST) and the phase unwrapping was carried out by the Cellular-automata method. We analysed the relief of a tilted flat metallic bar and a tooth prosthesis.

  1. Surface mineral mapping at Virginia City and Steamboat Springs, Nevada with multi-wavelength infrared remote sensing image data

    NASA Astrophysics Data System (ADS)

    Vaughan, R. Greg

    The purpose of this study was to use a combination of high spatial resolution airborne visible, near infrared, short wave infrared (VNIR/SWIR) and thermal infrared (TIR) image data to remotely identify and map exposed alteration minerals around both active and ancient hydrothermal systems, and the mineral by-products of weathered mine tailings. Three case study areas were evaluated: (1) Steamboat Springs, as an active geothermal system; (2) Geiger Grade and Virginia City, as ancient hydrothermal systems; and (3) Virginia City, as a historic mining district. Remote sensing data from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS), as well as data from newly developed airborne imaging spectrometers: SpecTIR Corporation's airborne hyperspectral imager (HyperSpecTIR), the MODIS-ASTER airborne simulator (MASTER), and the Spatially Enhanced Broadband Array Spectrograph System (SEBASS) were acquired and processed into mineral maps based on the unique spectral signatures of image pixels. VNIR/SWIR and TIR field spectrometer data were collected for both calibration and validation of the remote data sets, and field sampling, laboratory spectral analyses and XRD analyses were made to corroborate the surface mineralogy identified by spectroscopic methods. In all of the case study areas the minerals mapped included sinter, quartz/chalcedony, albite, calcite, dolomite, hydrous sulfate minerals (tamarugite, alunogen, gypsum and hexahydrite), jarosite, hematite, goethite, alunite, pyrophyllite, kaolinite, montmorillonite/muscovite, and chlorite. The results were synthesized into single thematic mineral maps and indicate that the combination of multi-channel infrared remote sensing data is an effective technique for the unique identification and mapping of weathering and alteration minerals that are characteristic of active and fossil hydrothermal systems, as well as acid mine drainage potential. This study provides many examples of the advantages of high spatial and

  2. Multi-wavelength Study of Transition Region Penumbral Bright Dots Using Interface Region Imaging Spectrograph and New Solar Telescope

    NASA Astrophysics Data System (ADS)

    Deng, Na; Yurchyshyn, Vasyl B.; Tian, Hui; Kleint, Lucia; Liu, Chang; Xu, Yan; Wang, Haimin

    2016-05-01

    Using high-resolution transition region (TR) observations taken by the Interface Region Imaging Spectrograph (IRIS) mission, Tian et al. (2014b) revealed numerous short-lived sub-arcsecond bright dots above sunspots (mostly located in the penumbrae), which indicate yet unexplained small-scale energy releases. Moreover, whether these TR brightenings have any signature in the lower atmosphere and how they are formed are still not fully resolved. This paper presents a study of these bright dots using a coordinated observation of a near disk-center sunspot with IRIS and the 1.6 m New Solar Telescope (NST) at the Big Bear Solar Observatory. NST provides high-resolution chromospheric and photospheric observations with narrow-band H-alpha imaging spectroscopy and broad-band TiO images, respectively, complementary to IRIS TR observations. A total of 2692 TR penumbral bright dots are identified from a 37-minute time series of IRIS 1400 A slitjaw images. Their locations tend to be associated more with downflowing and darker fibrils in the chromosphere, and weakly associated with bright penumbral features in the photosphere. However, temporal evolution analyses of the dots show that there is no consistent and convincing brightening response in the chromosphere. These results are compatible with a formation mechanism of the TR penumbral bright dots by falling plasma from coronal heights along more vertical and dense magnetic loops. The dots may also be produced by small-scale impulsive magnetic reconnection taking place sufficiently high in the atmosphere that has no energy release in the chromosphere.Acknowledgement: This work is mainly supported by NASA grants NNX14AC12G, NNX13AF76G and by NSF grant AGS 1408703.

  3. Mapping the Ionization State of Laser-Irradiated Ar Gas Jets With Multi-Wavelength Monochromatic X-Ray Imaging

    SciTech Connect

    Kugland, N L; Doppner, T; Kemp, A; Schaeffer, D; Glenzer, S H; Niemann, C

    2010-04-08

    Two-dimensional monochromatic images of fast-electron stimulated Ar K{alpha} and He-{alpha} x-ray self-emission have recorded a time-integrated map of the extent of Ar{sup {approx}6+} and Ar{sup 16+} ions, respectively, within a high density (10{sup 20} cm{sup -3} atomic density) Ar plasma. This plasma was produced by irradiating a 2 mm wide clustering Ar gas jet with an ultra-high intensity (10{sup 19} W/cm{sup 2}, 200 fs) Ti:Sapphire laser operating at 800 nm. Spherically bent quartz crystals in the 200 (for K{alpha}) and 201 (for He-{alpha}) planes were used as near-normal incidence reflective x-ray optics. We see that a large (830 {micro}m long) region of plasma emits K{alpha} primarily along the laser axis, while the He-{alpha} emission is confined to smaller hot spot (230 {micro}m long) region that likely corresponds to the focal volume of the f/8 laser beam. X-ray spectra from a Bragg spectrometer operating in the von Hamos geometry, which images in one dimension, indicate that the centroids of the K{alpha} and He-{alpha} emission regions are separated by approximately 330 {micro}m along the laser axis.

  4. Development of a generalized algorithm of satellite remote sensing using multi-wavelength and multi-pixel information (MWP method) for aerosol properties by satellite-borne imager

    NASA Astrophysics Data System (ADS)

    Hashimoto, M.; Nakajima, T.; Morimoto, S.; Takenaka, H.

    2014-12-01

    We have developed a new satellite remote sensing algorithm to retrieve the aerosol optical characteristics using multi-wavelength and multi-pixel information of satellite imagers (MWP method). In this algorithm, the inversion method is a combination of maximum a posteriori (MAP) method (Rodgers, 2000) and the Phillips-Twomey method (Phillips, 1962; Twomey, 1963) as a smoothing constraint for the state vector. Furthermore, with the progress of computing technique, this method has being combined with the direct radiation transfer calculation numerically solved by each iteration step of the non-linear inverse problem, without using LUT (Look Up Table) with several constraints.Retrieved parameters in our algorithm are aerosol optical properties, such as aerosol optical thickness (AOT) of fine and coarse mode particles, a volume soot fraction in fine mode particles, and ground surface albedo of each observed wavelength. We simultaneously retrieve all the parameters that characterize pixels in each of horizontal sub-domains consisting the target area. Then we successively apply the retrieval method to all the sub-domains in the target area.We conducted numerical tests for the retrieval of aerosol properties and ground surface albedo for GOSAT/CAI imager data to test the algorithm for the land area. The result of the experiment showed that AOTs of fine mode and coarse mode, soot fraction and ground surface albedo are successfully retrieved within expected accuracy. We discuss the accuracy of the algorithm for various land surface types. Then, we applied this algorithm to GOSAT/CAI imager data, and we compared retrieved and surface-observed AOTs at the CAI pixel closest to an AERONET (Aerosol Robotic Network) or SKYNET site in each region. Comparison at several sites in urban area indicated that AOTs retrieved by our method are in agreement with surface-observed AOT within ±0.066.Our future work is to extend the algorithm for analysis of AGEOS-II/GLI and GCOM/C-SGLI data.

  5. Multi-wavelength phase-shifting interferometry for micro-structures measurement based on color image processing in white light interference

    NASA Astrophysics Data System (ADS)

    Guo, Tong; Li, Feng; Chen, Jinping; Fu, Xing; Hu, Xiaotang

    2016-07-01

    Conventional multi-wavelength phase-shifting interferometry utilizes two or three monochromatic light sources, such as lasers, to realize the measurement of the surface topography with large discontinuity. In this paper, the white light source, with a single-chip CCD color camera, is used to accomplish multi-wavelength phase-shifting interferometry. In addition, we propose an algorithm which combines white light phase-shifting algorithm, equivalent wavelength method and fringe order method to achieve measuring and calibrating the micro-structures ranging from nanometer scale to micrometer scale. Finally, the proposed method is validated by a traceable step height standard.

  6. INTEGRAL FIELD SPECTROSCOPY AND MULTI-WAVELENGTH IMAGING OF THE NEARBY SPIRAL GALAXY NGC 5668 : AN UNUSUAL FLATTENING IN METALLICITY GRADIENT

    SciTech Connect

    Marino, R. A.; Gil de Paz, A.; Castillo-Morales, A.; Perez-Gonzalez, P. G.; Gallego, J.; Zamorano, J.; Sanchez, S. F.

    2012-07-20

    We present an analysis of the full bidimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the Pmas fiber PAcK Integral Field Unit (IFU) at the Calar Alto observatory 3.5 m telescope. We make use of broadband imaging to provide further constraints on the evolutionary history of the galaxy. This data set will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that while inward of r {approx}36'' {approx} 4.4 kpc {approx} 0.36 (D{sub 25}/2) the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r {approx} 36'' flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and circular velocity of {lambda} = 0.053 and v{sub c} = 167 km s{sup -1}, respectively. The metallicity gradient and rotation curve predicted by this best-fitting galaxy model nicely match the values derived from the IFU observations, especially within r {approx}36''. The same is true for the colors despite some small offsets and a reddening in the bluest colors beyond that radius. On the other hand, deviations of some of these properties in the outer disk indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC 5668.

  7. Fast fiber-optic multi-wavelength pyrometer

    NASA Astrophysics Data System (ADS)

    Fu, Tairan; Tan, Peng; Pang, Chuanhe; Zhao, Huan; Shen, Yi

    2011-06-01

    A fast fiber-optic multi-wavelength pyrometer was developed for the ultraviolet-visible-near infrared spectra from 200 nm to 1700 nm using a CCD detector and an InGaAs detector. The pyrometer system conveniently and quickly provides the sufficient choices of multiple measurement wavelengths using optical diffraction, which avoids the use of narrow-band filters. Flexible optical fibers are used to transmit the radiation so the pyrometer can be used for temperature measurements in harsh environments. The setup and calibrations (wavelength calibration, nonlinearity calibration, and radiation response calibration) of this pyrometer system were described. Development of the multi-wavelength pyrometer involved optimization of the bandwidth and temperature discrimination of the multiple spectra data. The analysis results showed that the wavelength intervals, ΔλCCD = 30 nm and ΔλInGaAs = 50 nm, are the suitable choices as a tradeoff between the simple emissivity model assumption and the multiple signal discrimination. The temperature discrimination was also quantificationally evaluated for various wavelengths and temperatures. The measurement performance of the fiber-optic multi-wavelength pyrometer was partially verified through measurements with a high-temperature blackbody and actual hot metals. This multi-wavelength pyrometer can be used for remote high-temperature measurements.

  8. A multi-wavelength (u.v. to visible) laser system for early detection of oral cancer

    NASA Astrophysics Data System (ADS)

    Najda, S. P.; Perlin, P.; Leszczyński, M.; Slight, T. J.; Meredith, W.; Schemmann, M.; Moseley, H.; Woods, J. A.; Valentine, R.; Kalra, S.; Mossey, P.; Theaker, E.; Macluskey, M.; Mimnagh, G.; Mimnagh, W.

    2015-03-01

    A multi-wavelength (360nm - 440nm), real-time Photonic Cancer Detector (PCD) optical system based on GaN semiconductor laser technology is outlined. A proof of concept using blue laser technology for early detection of cancer has already been tested and proven for esophageal cancer. This concept is expanded to consider a wider range of wavelengths and the PCD will initially be used for early diagnosis of oral cancers. The PCD creates an image of the oral cavity (broad field white light detection) and maps within the oral cavity any suspicious lesions with high sensitivity using a narrow field tunable detector.

  9. Oscillation signature from multi-wavelength analysis on solar chromosphere

    SciTech Connect

    Mumpuni, Emanuel Sungging; Herdiwijaya, Dhani; Djamal, Mitra

    2014-03-24

    In this work, we investigate how the solar chromosphere responds to the photospheric dynamics by using tomography study, implementing multiwavelength analysis observations obtained from Dutch Open Telescope. By using high resolution, high-quality, simultaneous image sequences of multi-wavelength data, we try to obtain the oscillation signature that might play important role on chromospheric dynamic by using H-alpha (Hα) as primary diagnostic tool.

  10. Multi-Wavelength Observations of Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Williams, B.

    2012-01-01

    Supernova remnants (SNRs) provide a laboratory for studying various astrophysical processes, including particle acceleration, thermal and non thermal emission processes across the spectrum, distribution of heavy elements, the physics of strong shock waves, and the progenitor systems and environments of supernovae. Long studied in radio and X-rays, the past decade has seen a dramatic increase in the detection and subsequent study of SNRs in the infrared and gamma-ray regimes. Understanding the evolution of SNRs and their interaction with the interstellar medium requires a multi-wavelength approach. I will review the various physical processes observed in SNRs and how these processes are intertwined. In particular, I will focus on X-ray and infrared observations, which probe two very different but intrinsically connected phases of the ISM: gas and dust. I will discuss results from multi-wavelength studies of several SNRs at various stages of evolution, including Kepler, RCW 86, and the Cygnus Loop.

  11. Multi-Wavelength Study of Segue 3

    NASA Astrophysics Data System (ADS)

    Hughes, Joanne D.; Schiefelbein, Spencer; Le, Donna; Corrin, Olivia; Joudi, Hanah; Lacy, Brianna I.

    2016-06-01

    Segue 3 is a very faint and distant star cluster, first identfied as being [Fe/H]=-1.7 dex, but later reclassified as [Fe/H]=-0.8. We study the stellar population in Washington and SDSS filters, adding to VI-photometry in the literature. We show the importance of multi-wavelength coverage, careful filter-selection, and use of the sub-giant and lower red-giant branch populations, to break the age-metallicity degeneracy.

  12. Imaging MAMA detector systems

    NASA Astrophysics Data System (ADS)

    Slater, David C.; Timothy, J. G.; Morgan, Jeffrey S.; Kasle, David B.

    1990-07-01

    Imaging multianode microchannel array (MAMA) detector systems with 1024 x 1024 pixel formats have been produced for visible and UV wavelengths; the UV types employ 'solar blind' photocathodes whose detective quantum efficiencies are significantly higher than those of currently available CCDs operating at far-UV and EUV wavelengths. Attention is presently given to the configurations and performance capabilities of state-of-the-art MAMA detectors, with a view to the development requirements of the hybrid electronic circuits needed for forthcoming spacecraft-sensor applications. Gain, dark noise, uniformity, and dynamic range performance data are presented for the curved-channel 'chevron', 'Z-plate', and helical-channel high gain microchannel plate configurations that are currently under evaluation with MAMA detector systems.

  13. Emissivity measurements of shocked tin using a multi-wavelength integrating sphere

    SciTech Connect

    Seifter, A; Holtkamp, D B; Iverson, A J; Stevens, G D; Turley, W D; Veeser, L R; Wilke, M D; Young, J A

    2011-11-01

    Pyrometric measurements of radiance to determine temperature have been performed on shock physics experiments for decades. However, multi-wavelength pyrometry schemes sometimes fail to provide credible temperatures in experiments, which incur unknown changes in sample emissivity, because an emissivity change also affects the spectral radiance. Hence, for shock physics experiments using pyrometry to measure temperatures, it is essential to determine the dynamic sample emissivity. The most robust way to determine the normal spectral emissivity is to measure the spectral normal-hemispherical reflectance using an integrating sphere. In this paper we describe a multi-wavelength (1.6–5.0 μm) integrating sphere system that utilizes a “reversed” scheme, which we use for shock physics experiments. The sample to be shocked is illuminated uniformly by scattering broadband light from inside a sphere onto the sample. A portion of the light reflected from the sample is detected at a point 12° from normal to the sample surface. For this experiment, we used the system to measure emissivity of shocked tin at four wavelengths for shock stress values between 17 and 33 GPa. The results indicate a large increase in effective emissivity upon shock release from tin when the shock is above 24–25 GPa, a shock stress that partially melts the sample. We also recorded an IR image of one of the shocked samples through the integrating sphere, and the emissivity inferred from the image agreed well with the integrating-sphere, pyrometer-detector data. Here, we discuss experimental data, uncertainties, and a data analysis process. We also describe unique emissivity-measurement problems arising from shock experiments and methods to overcome such problems.

  14. Fuzzy Neural Classifiers for Multi-Wavelength Interdigital Sensors

    NASA Astrophysics Data System (ADS)

    Xenides, D.; Vlachos, D. S.; Simos, T. E.

    2007-12-01

    The use of multi-wavelength interdigital sensors for non-destructive testing is based on the capability of the measuring system to classify the measured impendence according to some physical properties of the material under test. By varying the measuring frequency and the wavelength of the sensor (and thus the penetration depth of the electric field inside the material under test) we can produce images that correspond to various configurations of dielectric materials under different geometries. The implementation of a fuzzy neural network witch inputs these images for both quantitative and qualitative sensing is demonstrated. The architecture of the system is presented with some references to the general theory of fuzzy sets and fuzzy calculus. Experimental results are presented in the case of a set of 8 well characterized dielectric layers. Finally the effect of network parameters to the functionality of the system is discussed, especially in the case of functions evaluating the fuzzy AND and OR operations.

  15. Imaging alpha particle detector

    DOEpatents

    Anderson, D.F.

    1980-10-29

    A method and apparatus for detecting and imaging alpha particles sources is described. A dielectric coated high voltage electrode and a tungsten wire grid constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source to be quantitatively or qualitatively analyzed. A thin polyester film window allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

  16. Imaging alpha particle detector

    DOEpatents

    Anderson, David F.

    1985-01-01

    A method and apparatus for detecting and imaging alpha particles sources is described. A conducting coated high voltage electrode (1) and a tungsten wire grid (2) constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source (3) to be quantitatively or qualitatively analyzed. A thin polyester film window (4) allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

  17. ONSET-A New Multi-Wavelength Solar Telescope

    NASA Astrophysics Data System (ADS)

    Fang, C.; Chen, P. F.; Ding, M. D.; Dai, Y.; Li, Z.

    2012-06-01

    A new multi-wavelength solar telescope, Optical and Near-infrared Solar Eruption Tracer (ONSET), is constructed by Nanjing University, being run in cooperation with Yunnan Astronomical Observatory. ONSET is able to observe the Sun in three wavelength windows: He I 10830 Å, Hα and white-light at 3600 Å or 4250 Å. Full-disk or partial solar images with a field of 10 arcmin at three wavelengths can be obtained nearly simultaneously. It is designed to trace solar eruptions with high spatial and temporal resolutions. This telescope has been installed at a new solar observing site near the Fuxian Lake, Yunnan Province. The site is located at E102N24, with an altitude of 1722 m. The seeing is stable and very nice. We give a brief description of the scientific objectives and the basic structure of ONSET. Some preliminary results are also shown.

  18. Using the Virtual Observatory: multi-instrument, multi-wavelength study of high-energy sources

    NASA Astrophysics Data System (ADS)

    Derrière, S.; Goosmann, R. W.; Bot, C.; Bonnarel, F.

    2014-12-01

    This paper presents a tutorial explaining the use of Virtual Observatory tools in high energy astrophysics. Most of the tools used in this paper were developed at the Strasbourg astronomical Data Center and we show how they can be applied to conduct a multi-instrument, multi-wavelength analysis of sources detected by the High Energy Stereoscopic System and the Fermi Large Area Telescope. The analysis involves queries of different data catalogs, selection and cross-correlation techniques on multi-waveband images, and the construction of high energy color-color plots and multi-wavelength spectra. The tutorial is publicly available on the website of the European Virtual Observatory project.

  19. Multi-wavelength Observations of Neptune’s Atmosphere

    NASA Astrophysics Data System (ADS)

    de Pater, Imke; Fletcher, L.; Luszcz-Cook, S.; deBoer, D.; Butler, B.; Orton, G.; Sitko, M.; Hammel, H.

    2013-10-01

    We conducted a multi-wavelength observing campaign on Neptune between June and October, 2003. We used the 10-m Keck telescope at near- and mid-infrared wavelengths and the VLA at radio wavelengths. Near infrared images were taken in October 2003 in broad- and narrow-band filters between 1 and 2.5 micron, using the infrared camera NIRC2 coupled to the Keck Adaptive Optics system. At these wavelengths we detect sunlight reflected off clouds in the upper troposphere and lower stratosphere. As shown by various authors before, bright bands of discrete cloud features are visible between 20°S and 50°S and near 30°N, as well as several distinct bright cloud features near 70°S, and the south polar “dot”. Mid-infrared images were taken on September 5 and 6 (2003) using the Keck LWS system in atmospheric windows at 8, 8.9, 10.7, 11.7, 12.5, 17.65, 18.75 and 22 micron. At these wavelengths we detect thermal emission from Neptune’s stratosphere due to the presence of hydrocarbons, and from near the tropopause due to collision induced opacity by hydrogen. At all wavelengths the South polar region stands out as a bright spot. At 17 - 22 micron also the equatorial region is slightly enhanced in intensity. These characteristics are consistent with later imaging at similar wavelengths (Hammel et al. 2007; Orton et al. 2007). Microwave images were constructed from NRAO VLA data between 0.7 and 6.0 cm. At these wavelengths depths of several up to >50 bar are probed. An increase in brightness indicates decreased opacity of absorbers (e.g., NH3, H2S), since under such circumstances deep, and hence warm levels (adiabatic temperature-pressure profile), will be probed. The multi-wavelength observing campaign in 2003 was focused on obtaining images that probe different altitudes in Neptune’s atmosphere. Indeed, this set of data probes altitudes from about 0.1 mbar down to ~50 bar, and hence can be used to constrain the global atmospheric circulation in Neptune’s atmosphere. At

  20. Understanding Grb Physics With Multi-Wavelength Data

    NASA Astrophysics Data System (ADS)

    Zhang, Bing

    The study of Gamma-ray bursts (GRBs) has entered a full multi-wavelength era. A rich trove of data from NASA GRB missions and ground-based follow up observations have been collected. Careful data mining with well-defined scientific objectives holds the key to address open questions in GRB physics, such as jet composition, radiation mechanism, progenitor and central engine physics. We propose to perform data analyses in the following three directions. 1. The time resolved GRB spectra have a dominant component that can be fit with a phenomenological ``Band'' function. The physical meaning of this function remains unclear. Recently we made a breakthrough in theoretical modeling, and showed that fast-cooling synchrotron radiation of electrons in a decreasing magnetic field can mimic the Band function in detector's bandpass, but differs from Band function slightly. We propose to apply this physically-motivated model to systematically fit the GRB prompt emission data collected by Fermi GBM and LAT, and test whether the dominant GRB emission mechanism is fast cooling synchrotron radiation. We will also fit time-dependent spectra with a time-dependent model to investigate whether a quasi- thermal "photosphere'' emission component is indeed needed to fit the observed spectra. This would shed light onto the unknown composition of GRB jets. By fitting the time resolved spectra, we will also constrain important physical parameters of GRB prompt emission, such as the emission site of GRBs, the strength of magnetic fields, as well as their evolution with radius. 2. Recent GRB multi-wavelength observations suggest that it is not straightforward to define the physical category of a GRB based on the traditional classification in the "duration''-"hardness'' domain. Some long-duration GRBs may not have a massive star origin, while some short-duration GRBs may instead have a massive star origin. We propose to systematically study the gamma-ray Swift/BAT, Fermi/GBM- LAT), X-ray (Swift

  1. Multi-Wavelength Photoacoustic Visualization of High Intensity Focused Ultrasound Lesions

    PubMed Central

    Gray, J. P.; Dana, N.; Dextraze, K. L.; Maier, F.; Emelianov, S.; Bouchard, R. R.

    2016-01-01

    High intensity focused ultrasound (HIFU) thermal therapies are limited by deficiencies in existing image-guidance techniques. Previous studies using single-wavelength photoacoustic (PA) imaging have demonstrated that HIFU lesions generate contrast with respect to native tissues but have not sufficiently assessed lesion extent. The purpose of this study is to demonstrate feasibility of characterization of in vitro HIFU ablation lesion dimensions using 3D multi-wavelength PA imaging. Fresh porcine cardiac and liver tissue samples were embedded in agar phantoms and ablated using a 2.5 MHz small-animal HIFU system. Both 2D and 3D multi-wavelength photoacoustic-ultrasonic (PAUS) scans were performed in the near-infrared (NIR) range to characterize the change in the absorption spectrum of tissues following ablation and were compared to stained gross pathology to assess treatment margins and lesion extent. Comprehensive 2D multi-wavelength PA imaging yielded a spectrum in ablated tissue that did not display the characteristic local maximum in the optical absorption spectrum of deoxy-hemoglobin (Hb) near 760 nm. Two-dimensional tissue characterization map (TCM) images reconstructed from 3D TCM volumes reliably characterized lesion area and showed >70% area agreement with stained gross pathology. In addition, tissue samples were heated via water bath and concurrently interrogated with 2D PAUS imaging. PA signal exhibited an initial amplitude increase across all wavelengths, corresponding to an initial temperature increase, before then exhibiting a spectral change. This study suggests that multi-wavelength PA imaging has potential to obtain accurate characterization of HIFU lesion extent and may be better suited to guide HIFU ablation therapies during clinical treatments than single-wavelength methods. PMID:26149314

  2. Multi-wavelength follow-up of ANTARES neutrino alerts

    NASA Astrophysics Data System (ADS)

    Mathieu, Aurore

    2015-10-01

    Transient sources are often associated with the most violent phenomena in the Universe, where the acceleration of hadrons may occur. Such sources include gamma-ray bursts (GRBs), active galactic nuclei (AGN) or core-collapse supernovae (CCSNe), and are promising candidates for the production of high energy cosmic rays and neutrinos. The ANTARES telescope, located in the Mediterranean sea, aims at detecting these high energy neutrinos, which could reveal the presence of a cosmic ray accelerator. However, to enhance the sensitivity to transient sources, a method based on multi-wavelength follow-up of neutrino alerts has been developed within the ANTARES collaboration. This program, denoted as TAToO, triggers a network of robotic optical telescopes and the Swift-XRT with a delay of only a few seconds after a neutrino detection. The telescopes start an observation program of the corresponding region of the sky in order to detect a possible electromagnetic counterpart to the neutrino event. The work presented in this thesis covers the development and implementation of an optical image analysis pipeline, as well as the analysis of optical and X-ray data to search for fast transient sources, such as GRB afterglows, and slowly varying transient sources, such as CCSNe.

  3. Multi-Wavelength Diagnostics of Starbirth in Starbursts

    NASA Astrophysics Data System (ADS)

    Waller, William

    2005-07-01

    From the Orion Nebula to the Hubble Deep Field, starburst activity can be seen transforming galaxian clouds of gas into populous clusters of stars. The pyrotechnics and chemical enrichment associated with this activity have led to outcomes as ubiquitous as interstellar dust and as exquisite as life on Earth. In this talk, I will focus on the circumstances of star formation in the environmental context of ongoing starburst activity. I begin with the premises that (1) the formation of a single star takes time, (2) the formation of a populous cluster takes even more time, and (3) ``stuff'' happens in the interim. Hubble images of the Orion Nebula and Eagle Nebula show how hot stars can excavate neighboring clouds of gas and photoevaporate the star-forming cores that are exposed. Hubble observations of giant HII regions in M33 reveal a significant variation in the stellar populations, such that the most metal-rich HII regions contain the greatest proportions of the most massive stars. ISO and Spitzer observations of these same HII regions reveal corresponding variations in the nebular response. These multi-wavelength diagnostics of the stellar-nebular feedback in galaxian starbursts suggest a star-forming mechanism which is subject to photo-evaporative ablation -- an erosive process that is mediated by the metal abundance and corresponding amounts of protective dust in the starbursting environment.

  4. Theoretical and experimental investigation of multi-wavelength fiber laser

    NASA Astrophysics Data System (ADS)

    Wo, Jianghai; Sun, Qizhen

    2009-08-01

    In this paper, a method for realizing a stable multi-wavelength EDFL at room temperature is analyzed theoretically and obtained experimentally. We have proposed a multi-wavelength fiber ring cavity laser by using EDF as the gain medium. A F-P and a band-pass filter are inserted into the cavity to achieve the selection of multi-wavelength. Meanwhile, by inserting a nonlinear optical loop mirror (NOLM) in the linear cavity, which can suppresses the mode competition owing to the homogeneous broaden line in EDF and eliminates the unstable single wavelength lasing, stable output can be obtained at room temperature. As a result, power-stable, broad bandwidth and uniform multi-wavelength operations with narrow line-width and high side mode suppression ratio are obtained at room temperature. In addition, we also demonstrate a kind of tunable multi-wavelength EDFL based on multi-channel FBG (M-FBG). Four-wavelength output with the flatness and SNR of almost 1dB and more than 50dB is achieved and the output wavelength can be changed by applying stress on the M-FBG.

  5. Multi-Wavelength Views of Messier 81

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site] Click on individual images below for larger view

    [figure removed for brevity, see original site]

    [figure removed for brevity, see original site]

    [figure removed for brevity, see original site]

    [figure removed for brevity, see original site]

    The magnificent spiral arms of the nearby galaxy Messier 81 are highlighted in this image from NASA's Spitzer Space Telescope. Located in the northern constellation of Ursa Major (which also includes the Big Dipper), this galaxy is easily visible through binoculars or a small telescope. M81 is located at a distance of 12 million light-years.

    The main image is a composite mosaic obtained with the multiband imaging photometer for Spitzer and the infrared array camera. Thermal infrared emission at 24 microns detected by the photometer (red, bottom left inset) is combined with camera data at 8.0 microns (green, bottom center inset) and 3.6 microns (blue, bottom right inset).

    A visible-light image of Messier 81, obtained at Kitt Peak National Observatory, a ground-based telescope, is shown in the upper right inset. Both the visible-light picture and the 3.6-micron near-infrared image trace the distribution of stars, although the Spitzer image is virtually unaffected by obscuring dust. Both images reveal a very smooth stellar mass distribution, with the spiral arms relatively subdued.

    As one moves to longer wavelengths, the spiral arms become the dominant feature of the galaxy. The 8-micron emission is dominated by infrared light radiated by hot dust that has been heated by nearby luminous stars. Dust in the galaxy is bathed by ultraviolet and visible light from nearby stars. Upon absorbing an ultraviolet or visible-light photon, a dust grain is heated and re-emits the energy at longer infrared wavelengths. The dust particles are composed of silicates (chemically similar to beach sand), carbonaceous grains and polycyclic aromatic hydrocarbons and

  6. Mercubic iodine imaging detectors

    NASA Astrophysics Data System (ADS)

    Ortale, C.; Padgett, L.; Schnepple, W. F.

    1983-07-01

    Linear and two-dimensional monolithic arrays of different configurations have been fabricated using photolithographic techniques. The fabrication technology, electronic setup, and pinhole imaging experiments are described. Spatial resolutions of 1-2 mm have been achieved.

  7. Identification of aerosol composition from multi-wavelength lidar measurements

    NASA Technical Reports Server (NTRS)

    Wood, S. A.

    1984-01-01

    This paper seeks to develop the potential of lidar for the identification of the chemical composition of atmospheric aerosols. Available numerical computations suggest that aerosols can be identified by the wavelength dependence of aerosol optical properties. Since lidar can derive the volume backscatter coefficient as a function of wavelength, a multi-wavelength lidar system may be able to provide valuable information on the composition of aerosols. This research theoretically investigates the volume backscatter coefficients for the aerosol classes, sea-salts, and sulfates, as a function of wavelength. The results show that these aerosol compositions can be characterized and identified by their backscatter wavelength dependence. A method to utilize multi-wavelength lidar measurements to discriminate between compositionally different thin aerosol layers is discussed.

  8. Swift Multi-wavelength Observing Campaigns: Strategies and Outcomes

    NASA Technical Reports Server (NTRS)

    Krimm, Hans A.

    2007-01-01

    The Swift gamma-ray burst explorer has been operating since December 2004 as both a gamma-ray burst (GRB) monitor and telescope and a multi-wavelength observatory, covering the energy range from V band and near UV to hard X rays above 150 keV. It is designed to rapidly repoint to observe newly discovered GRBs, and this maneuverability, combined with an easily changed observing program, allows Swift to also be an effective multiwavelength observatory for non-GRB targets, both as targets of opportunity and pre-planned multi-wavelength observing campaigns. Blazars are particularly attractive targets for coordinated campaigns with TeV experiments since many blazars are bright in both the hard X-ray and TeV energy ranges. Successful coordinated campaigns have included observations of 3C454.3 during its 2005 outburst. The latest Swift funding cycles allow for non- GRB related observations to be proposed. The Burst Alert Telescope on Swift also serves as a hard X-ray monitor with a public web page that includes light curves for over 400 X-ray sources and is used to alert the astronomical community about increased activity from both known and newly discovered sources. This presentation mill include Swift capabilities, strategies and policies for coordinated multi-wavelength observations as well as discussion of the potential outcomes of such campaigns.

  9. Multi-wavelength differential absorption measurements of chemical species

    NASA Astrophysics Data System (ADS)

    Brown, David M.

    algorithms to select filters for use with a MWIR (midwave infrared) imager for detection of plumes of methane, propane, gasoline vapor, and diesel vapor. These simulations were prepared for system designs operating on a down-looking airborne platform. A data analysis algorithm for use with a hydrocarbon imaging system extracts regions of interest from the field-of-view for further analysis. An error analysis is presented for a scanning DAS (Differential Absorption Spectroscopy) lidar system operating from an airborne platform that uses signals scattered from topographical targets. The analysis is built into a simulation program for testing real-time data processing approaches, and to gauge the effects on measurements of path column concentration due to ground reflectivity variations. An example simulation provides a description of the data expected for methane. Several accomplishments of this research include: (1) A new lidar technique for detection and measurement of concentrations of atmospheric species is demonstrated that uses a low-power supercontinuum source. (2) A new multi-wavelength algorithm, which demonstrates excellent performance, is applied to processing spectroscopic data collected by a longpath supercontinuum laser absorption instrument. (3) A simulation program for topographical scattering of a scanning DAS system is developed, and it is validated with aircraft data from the ITT Industries ANGEL (Airborne Natural Gas Emission Lidar) 3-lambda lidar system. (4) An error analysis procedure for DAS is developed, and is applied to measurements and simulations for an airborne platform. (5) A method for filter selection is developed and tested for use with an infrared imager that optimizes the detection for various hydrocarbons that absorb in the midwave infrared. (6) The development of a Fourier analysis algorithm is described that allows a user to rapidly separate hydrocarbon plumes from the background features in the field of view of an imaging system.

  10. Integrating IR detector imaging systems

    NASA Technical Reports Server (NTRS)

    Bailey, G. C. (Inventor)

    1984-01-01

    An integrating IR detector array for imaging is provided in a hybrid circuit with InSb mesa diodes in a linear array, a single J-FET preamplifier for readout, and a silicon integrated circuit multiplexer. Thin film conductors in a fan out pattern deposited on an Al2O3 substrate connect the diodes to the multiplexer, and thick film conductors also connect the reset switch and preamplifier to the multiplexer. Two phase clock pulses are applied with a logic return signal to the multiplexer through triax comprised of three thin film conductors deposited between layers. A lens focuses a scanned image onto the diode array for horizontal read out while a scanning mirror provides vertical scan.

  11. Molecular transport network security using multi-wavelength optical spins.

    PubMed

    Tunsiri, Surachai; Thammawongsa, Nopparat; Mitatha, Somsak; Yupapin, Preecha P

    2016-01-01

    Multi-wavelength generation system using an optical spin within the modified add-drop optical filter known as a PANDA ring resonator for molecular transport network security is proposed. By using the dark-bright soliton pair control, the optical capsules can be constructed and applied to securely transport the trapped molecules within the network. The advantage is that the dark and bright soliton pair (components) can securely propagate for long distance without electromagnetic interference. In operation, the optical intensity from PANDA ring resonator is fed into gold nano-antenna, where the surface plasmon oscillation between soliton pair and metallic waveguide is established. PMID:25058032

  12. Near-infrared multi-wavelengths long persistent luminescence of Nd3+ ion through persistent energy transfer in Ce3+, Cr3+ co-doped Y3Al2Ga3O12 for the first and second bio-imaging windows

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Tanabe, Setsuhisa; Sontakke, Atul D.; Ueda, Jumpei

    2015-08-01

    We developed a persistent phosphor of Y3Al2Ga3O12 doped with Nd3+, Ce3+, Cr3+ ions (YAGG:Nd-Ce-Cr) exhibiting long (>10 h) persistent luminescence at multi-wavelengths of around 880, 1064, and 1335 nm due to f-f transitions of Nd3+ and at 505 nm due to Ce3+:5d1→4f transition. The intense near-infrared (NIR) persistent luminescence bands from Nd3+ match well with the first (650-950 nm) and second (1000-1400 nm) bio-imaging windows. The NIR persistent radiance of the YAGG:Nd-Ce-Cr phosphor (0.33 × 10-1 mW/Sr/m2) at 60 min after ceasing blue light illumination was over 2 times higher than that of the widely used ZnGa2O4:Cr3+ red persistent phosphor (0.15 × 10-1 mW/Sr/m2).

  13. Multi-wavelength coverage of outburst decays of LMXBs

    NASA Astrophysics Data System (ADS)

    Kalemci, Emrah; Tomsick, John; Bailyn, Charles; Dincer, Tolga

    2016-07-01

    Low mass X-ray binaries (LMXB) are dynamic laboratories that are powered by accretion, and under some conditions these systems create strong outflows in the form of highly collimated jets, or winds. Outburst decays of transient LMXBs provide additional information about compact jets and their relation to changes in timing properties. Our group characterizes the multi-wavelength evolution of Galactic black hole transients during their outburst decays using simultaneous X-ray (RXTE, Swift, and INTEGRAL), optical/infrared (SMARTS) and radio (VLA, ATCA, VLBI). By characterizing the X-ray spectral and timing evolution of these systems, and merging this information with the evolution in the near-infrared and radio, we obtain the conditions necessary to launch stable compact jets, and discuss how jets can be influencing and/or influenced by X-ray timing and spectral properties of these systems. In this presentation, I will summarize recent results regarding multi-wavelength observations of not only black hole systems, but also neutron star X-ray binaries during outburst decays, and discuss models that explain not only the broad spectral energy distribution, but also some of the timing properties of these systems.

  14. Fast time-lens-based line-scan single-pixel camera with multi-wavelength source

    PubMed Central

    Guo, Qiang; Chen, Hongwei; Weng, Zhiliang; Chen, Minghua; Yang, Sigang; Xie, Shizhong

    2015-01-01

    A fast time-lens-based line-scan single-pixel camera with multi-wavelength source is proposed and experimentally demonstrated in this paper. A multi-wavelength laser instead of a mode-locked laser is used as the optical source. With a diffraction grating and dispersion compensating fibers, the spatial information of an object is converted into temporal waveforms which are then randomly encoded, temporally compressed and captured by a single-pixel photodetector. Two algorithms (the dictionary learning algorithm and the discrete cosine transform-based algorithm) for image reconstruction are employed, respectively. Results show that the dictionary learning algorithm has greater capability to reduce the number of compressive measurements than the DCT-based algorithm. The effective imaging frame rate increases from 200 kHz to 1 MHz, which shows a significant improvement in imaging speed over conventional single-pixel cameras. PMID:26417527

  15. Multi-wavelength Monitoring of Lensed Quasars: Deciphering Quasar Structure at Micro-arcseconds Scales

    NASA Astrophysics Data System (ADS)

    Mosquera, Ana; Morgan, Christopher W.; Kochanek, Christopher S.; Dai, Xinyu; Chen, Bin; MacLeod, Chelsea Louise; Chartas, George

    2016-01-01

    Microlensing in multiply imaged gravitationally lensed quasars provides us with a unique tool to zoom in on the structure of AGN and explore their physics in more detail. Microlensing magnification, caused primarily by stars and white dwarfs close to the line of sight towards the lensed quasar images, is seen as uncorrelated flux variations due to the relative motions of the quasar, the lens, its stars, and the observer, and it depends on the structural and dynamical properties of the source and the lens. Since the magnification depends upon the size of the source, we can use microlensing to measure the size of quasar emission regions. In essence, the amplitude of the microlensing variability encodes the source size, with smaller sources showing larger variability amplitudes. Using state of the art microlensing techniques, our team has performed pioneering research in the field based on multi-wavelength space and ground-based observations. Among the most remarkable results, using Chandra observations we have set the first quantitative constraints on the sizes of the X-ray emission regions of quasars. In this work l briefly describe the methodology, the results from our previous multi-wavelength monitoring programs, and the next frontier of exploring the dependence of the structure of the X-ray emission regions on black hole mass and X-ray energy.

  16. Current state of ring imaging Cherenkov detectors

    SciTech Connect

    Coutrakon, G.B.

    1984-02-01

    This paper reviews several ring imaging Cherenkov detectors which are being used or developed to identify particles in high energy physics experiments. These detectors must have good detection efficiency for single photon-electrons and good spatial resolution over a large area. Emphasis is placed on the efficiencies and resolutions of these detectors as determined from ring imaging beam tests and other experiments. Following a brief review of the ring imaging technique, comparative evaluations are made of different forms of detectors and their respective materials.

  17. Initiation of Coronal Mass Ejection Event Observed on 2010 November 3: Multi-wavelength Perspective

    NASA Astrophysics Data System (ADS)

    Mulay, Sargam; Subramanian, Srividya; Tripathi, Durgesh; Isobe, Hiroaki; Glesener, Lindsay

    2014-10-01

    One of the major unsolved problems in solar physics is that of coronal mass ejection (CME) initiation. In this paper, we have studied the initiation of a flare-associated CME that occurred on 2010 November 3 using multi-wavelength observations recorded by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and the Reuven Ramaty High Energy Solar Spectroscopic Imager. We report an observation of an inflow structure initially in the 304 Å and the 1600 Å images a few seconds later. This inflow structure was detected as one of the legs of the CME. We also observed a non-thermal compact source concurrent and near co-spatial with the brightening and movement of the inflow structure. The appearance of this compact non-thermal source, brightening, and movement of the inflow structure and the subsequent outward movement of the CME structure in the corona led us to conclude that the CME initiation was caused by magnetic reconnection.

  18. Initiation of coronal mass ejection event observed on 2010 November 3: multi-wavelength perspective

    SciTech Connect

    Mulay, Sargam; Subramanian, Srividya; Tripathi, Durgesh; Isobe, Hiroaki; Glesener, Lindsay

    2014-10-10

    One of the major unsolved problems in solar physics is that of coronal mass ejection (CME) initiation. In this paper, we have studied the initiation of a flare-associated CME that occurred on 2010 November 3 using multi-wavelength observations recorded by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory and the Reuven Ramaty High Energy Solar Spectroscopic Imager. We report an observation of an inflow structure initially in the 304 Å and the 1600 Å images a few seconds later. This inflow structure was detected as one of the legs of the CME. We also observed a non-thermal compact source concurrent and near co-spatial with the brightening and movement of the inflow structure. The appearance of this compact non-thermal source, brightening, and movement of the inflow structure and the subsequent outward movement of the CME structure in the corona led us to conclude that the CME initiation was caused by magnetic reconnection.

  19. Multi-wavelength analysis of Ellerman Bomb Light Curves

    NASA Astrophysics Data System (ADS)

    Herlender, M.; Berlicki, A.

    We present the results of a multi-wavelength photometric analysis of Ellerman Bomb (EB) observations obtained from the Dutch Open Telescope. In our data we have found 6 EBs located in the super-penumbra of the main spot in the active region NOAA 10781. We present light curves of EB observed in the Hα line centre and wing +0.7 Å, in the Ca II H line centre and wing~+2.35 Å, in the G-band and in the TRACE 1600 Å filter. We have shown that EBs were visible in the G-band and moreover, there was a good correlation between the light curves in the G-band and in the Hα line wings. We also found quasi-periodic oscillations of EBs brightness in the G-band, CaII H line and TRACE 1600 Å filter.

  20. Emissivity range constraints algorithm for multi-wavelength pyrometer (MWP).

    PubMed

    Xing, Jian; Rana, R S; Gu, Weihong

    2016-08-22

    In order to realize rapid and real temperature measurement for high temperature targets by multi-wavelength pyrometer (MWP), emissivity range constraints to optimize data processing algorithm without effect from emissivity has been developed. Through exploring the relation between emissivity deviation and true temperature by fitting of large number of data from different emissivity distribution target models, the effective search range of emissivity for every time iteration is obtained, so data processing time is greatly reduced. Simulation and experimental results indicate that calculation time is less by 0.2 seconds with 25K absolute error at 1800K true temperature, and the efficiency is improved by more than 90% compared with the previous algorithm. The method has advantages of simplicity, rapidity, and suitability for in-line high temperature measurement. PMID:27557198

  1. Multi-wavelength analysis from tomography study on solar chromosphere

    SciTech Connect

    Mumpuni, Emanuel Sungging; Herdiwijaya, Dhani; Djamal, Mitra

    2015-04-16

    The Sun as the most important star for scientific laboratory in astrophysics as well as encompassing all living aspect on Earth, still holds scientific mystery. As the established model that the Sun’s energy fueled by the nuclear reaction, along with transport process to the typical Solar surface on around 6000-K temperature, many aspects still left as an open questions, such as how the chromosphere responded to the photospheric dynamics. In this preliminary work, we try to analyze the Solar chromosphere respond to the Photospheric dynamics using tomography study implementing multi-wavelength analysis observation obtained from Dutch Open Telescope. Using the Hydrogen-alpha Doppler signal as the primary diagnostic tool, we try to investigate the inter-relation between the magnetic and gas pressure dynamics that occur in the chromosphere.

  2. Multi-Wavelength Monitoring of GRS 1915+105

    NASA Technical Reports Server (NTRS)

    Bandyopadhyay, R.; Martini, P.; Gerard, E.; Charles, P. A.; Wagner, R. M.; Shrader, C.; Shahbaz, T.; Mirabel, I. F.

    1997-01-01

    Since its discovery in 1992, the superluminal X-ray transient GRS 1915+105 has been extensively observed in an attempt to understand its behaviour. We present here first results from a multi-wavelength campaign undertaken from July to September 1996. This study includes X-ray data from the RXTE All Sky Monitor and BATSE, two-frequency data from the Nancay radio telescope, and infrared photometry from the 1.8 m Perkins telescope at Lowell Observatory. The first long-term well-sampled IR light curve of GRS 1915+105 is presented herein and is consistent with the interpretation of this source as a long-period binary. We compare the various light curves, searching for correlations in the behaviour of the source at differing wavelengths and for possible periodicities.

  3. Intravascular imaging with a storage phosphor detector

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.; Petrek, Peter; Matthews, Kenneth L., II; Fritz, Shannon G.; Bujenovic, L. Steven; Xu, Tong

    2010-05-01

    The aim of this study is to develop and test an intravascular positron imaging system based on a storage phosphor detector for imaging and detecting vulnerable plaques of human coronary arteries. The radiotracer F18-FDG accumulates in vulnerable plaques with inflammation of the overlying cap. The vulnerable plaques can, therefore, be imaged by recording positrons emitted from F18-FDG with a detector inserted into the artery. A prototype intravascular detector was constructed based on storage phosphor. The detector uses a flexible storage phosphor tube with 55 mm length, 2 mm diameter and 0.28 mm wall thickness. The intravascular detector is guided into the vessel using x-ray fluoroscopy and the accumulated x-ray signal must be erased prior to positron imaging. For this purpose, a light diffuser, 0.9 mm in diameter and 55 mm in length, was inserted into the detector tube. The light diffuser was connected to a laser source through a 2 m long optical fiber. The diffuser redirected the 0.38 W laser light to the inner surface of the phosphor detector to erase it. A heart phantom with 300 cm3 volume and three coronary arteries with 3.2 mm diameter and with several plaques was constructed. FDG solution with 0.5 µCi cm-3 activity concentration was filled in the heart and coronary arteries. The detector was inserted in a coronary artery and the signal from the plaques and surrounding background activity was recorded for 2 min. Then the phosphor detector was extracted and read out using a storage phosphor reader. The light diffuser erased the signal resulting from fluoroscopic exposure to level below that encountered during positron imaging. Vulnerable plaques with area activities higher than 1.2 nCi mm-2 were visualized by the detector. This activity is a factor of 10-20 lower than that expected in human vulnerable plaques. The detector was able to image the internal surface of the coronary vessels with 50 mm length and 360° circumference. Spatial resolution was 0

  4. Enhanced neutron imaging detector using optical processing

    SciTech Connect

    Hutchinson, D.P.; McElhaney, S.A.

    1992-08-01

    Existing neutron imaging detectors have limited count rates due to inherent property and electronic limitations. The popular multiwire proportional counter is qualified by gas recombination to a count rate of less than 10{sup 5} n/s over the entire array and the neutron Anger camera, even though improved with new fiber optic encoding methods, can only achieve 10{sup 6} cps over a limited array. We present a preliminary design for a new type of neutron imaging detector with a resolution of 2--5 mm and a count rate capability of 10{sup 6} cps pixel element. We propose to combine optical and electronic processing to economically increase the throughput of advanced detector systems while simplifying computing requirements. By placing a scintillator screen ahead of an optical image processor followed by a detector array, a high throughput imaging detector may be constructed.

  5. Ghost imaging with a single detector

    SciTech Connect

    Bromberg, Yaron; Katz, Ori; Silberberg, Yaron

    2009-05-15

    We experimentally demonstrate pseudothermal ghost imaging and ghost diffraction using only a single detector. We achieve this by replacing the high-resolution detector of the reference beam with a computation of the propagating field, following a recent proposal by Shapiro [Phys. Rev. A 78, 061802(R) (2008)]. Since only a single detector is used, this provides experimental evidence that pseudothermal ghost imaging does not rely on nonlocal quantum correlations. In addition, we show the depth-resolving capability of this ghost imaging technique.

  6. Development of a Thermal/Optical Carbon Analyzer with Multi-Wavelength Capabilities

    NASA Astrophysics Data System (ADS)

    Sumlin, B.; Chow, J. C.; Watson, J. G.; Wang, X.; Gronstal, S.; Chen, L. W. A. A.; Trimble, D.

    2014-12-01

    A thermal/optical carbon analyzer (DRI Model 2015) equipped with a novel seven-wavelength light source (405, 445, 532, 635, 780, 808, and 980 nm) was developed to analyze chemical and optical properties of particles collected on quartz-fiber filters. Based on the DRI Model 2001 carbon analyzer at 633 nm, major modifications were made on mechanical and electrical components, flow control, and the carbon detector to adopt modern technologies, increase instrument reliability, and reduce costs and maintenance. The correlation between wavelength-dependent light attenuation and organic and elemental carbon (OC and EC, respectively) content allows estimation of the amount of brown and black carbon (BrC and BC, respectively) on filters. Continuous monitoring of the light reflected from and transmitted through the filter along with carbon evolved from the filter when heated to different temperatures under either inert or oxidizing gas environments provides insights into the optical properties of the carbon released from the filter; it also allows examination of the charring process as pyrolyzed char has been one of the major uncertainties in quantifying OC and EC. The objectives of this study are: 1) establish performance equivalency between the Model 2015 and Model 2001 DRI carbon analyzers when comparing similar laser wavelength to maintain consistency for long-term network sample analysis; and 2) analyze the multi-wavelength signal to quantify BrC and BC, and to optimize char correction. A selection of samples, including standard chemicals, rural and urban ambient filters, and emission sources from biomass burning, diesel and gasoline engine exhaust, and resuspended dust were measured by both the Model 2015 and Model 2001 analyzers. The instrument design, calibration, comparison with legacy analyzer, and interpretation of the multi-wavelengths measurement will be presented.

  7. Tomographic imaging using poissonian detector data

    DOEpatents

    Aspelmeier, Timo; Ebel, Gernot; Hoeschen, Christoph

    2013-10-15

    An image reconstruction method for reconstructing a tomographic image (f.sub.j) of a region of investigation within an object (1), comprises the steps of providing detector data (y.sub.i) comprising Poisson random values measured at an i-th of a plurality of different positions, e.g. i=(k,l) with pixel index k on a detector device and angular index l referring to both the angular position (.alpha..sub.l) and the rotation radius (r.sub.l) of the detector device (10) relative to the object (1), providing a predetermined system matrix A.sub.ij assigning a j-th voxel of the object (1) to the i-th detector data (y.sub.i), and reconstructing the tomographic image (f.sub.j) based on the detector data (y.sub.i), said reconstructing step including a procedure of minimizing a functional F(f) depending on the detector data (y.sub.i) and the system matrix A.sub.ij and additionally including a sparse or compressive representation of the object (1) in an orthobasis T, wherein the tomographic image (f.sub.j) represents the global minimum of the functional F(f). Furthermore, an imaging method and an imaging device using the image reconstruction method are described.

  8. A search for binary pulsar companions using multi-wavelength OBSERVATIONS

    NASA Astrophysics Data System (ADS)

    Mignani, Roberto; Yershov, Vladimir; Oates, Samantha; Breeveld, Alice; Pallanca, Cristina; Corongiu, Alessandro; Ferraro, Francesco

    The identification of the stellar companions to binary pulsars is key to study the evolution of the binary system and how this is influenced by the interactions between the two stars. For only a fraction of the known binary pulsars, the stellar companion has been identified. Here, we used 11 source catalogues available from multi-wavelength (optical, infrared, ultraviolet) imaging sky surveys, including the recently released Swift/UVOT and XMM-Newton/OM, to search for the stellar companions of a sample of 144 field binary pulsars (i.e. not in Globular Clusters) selected from the Australia Telescope National Facility (ATNF) data base (version 1.48) and from the public list of gamma-ray pulsars detected by Fermi.

  9. Multi-wavelength analysis of young pulsars: an overview.

    NASA Astrophysics Data System (ADS)

    Maritz, J. M.; Meintjes, P. J.; Buchner, S. J.

    Young pulsars emit a broad spectrum of radiation that range from radio to gamma ray energies. These pulsars are considered as rotation powered pulsars that spin rapidly and are strongly magnetized. Following the discovery of pulsars nearly four decades ago, the population of known pulsars already reached a number of roughly two thousand. This known population of pulsars includes both millisecond and normal pulsars that were discovered by several telescopes. We analyze both HartRAO radio data and Fermi gamma ray data of the Vela pulsar. We also explore a proposed method of probing the electron column density of the instellar gas through analyzing the gamma ray diffuse data associated with the Fermi two-year observation. This paper serves as an overview of gamma ray and radio timing analysis of bright young pulsars with respect to the use of open source timing analysis tools (Tempo2, Psrchive, Enrico and the Fermi tools). We reason that the multi-wavelength picture of pulsars can help clarify questions regarding the origin of pulsed radiation emission mechanisms in several energy bands, but that radio observations will prove adequate for timing noise analysis, given the accurate and long radio data sets. The process of identifying gravitational waves in timing data, rests on gaining a deeper insight into the timing noise phenomena.

  10. 40nm tunable multi-wavelength fiber laser

    NASA Astrophysics Data System (ADS)

    Jia, Qingsong; Wang, Tianshu; Zhang, Peng; Dong, Keyan; Jiang, Huilin

    2014-12-01

    A Brillouin-Erbium multi-wavelength tunable fiber laser at C-band is demostrated. A 10 km long singlemode fiber(SMF), a 6 m long Erbium-doped fiber, two couplers, a wavelength division multiplexer, a isolator, an optical circulator, a 980nm pump laser and a narrow linewidth tunable laser are included in the structure. A segment of 10 km-long single-mode fiber (SMF) between the two ports of a 1×2 coupler is used as Brillouin gain. Ebiumdoped fiber amplifier (EDFA) consists of a segment of 6m er-doped fiber pumped by 980nm laser dioder . A narrow linewidth tunable laser from 1527 to 1607 nm as Brillouin bump, At the Brillouin pump power of 8mW and the 980 nm pump power of 400 mw, 16 output channels with 0.08 nm spacing and tuning range of 40 nm from 1527 nm to 1567 nm are achieved. We realize the tunable output of wavelength by adjusting the 980 nm pump power and the Brillouin pump wavelength. Stability of the multiwavelength fiber laser is also observed.

  11. A Multi-wavelength Ozone Lidar for the EASOE Experiment

    NASA Technical Reports Server (NTRS)

    Godin, S.; Ancellet, G.; David, C.; Porteneuve, J.; Leroy, C.; Mitev, V.; Emery, Y.; Flesia, C.; Rizi, V.; Visconti, G.

    1992-01-01

    The study of the ozone layer during winter and springtime in high latitude regions is a major issue in atmospheric research. For a better understanding of these problems, an important experimental campaign called EASOE (European Arctic Stratospheric Ozone Experiment) was organized by the European Community during the winter 1991-1992. Its main objective was to establish a budget of the ozone destruction processes on the whole northern hemisphere. This implied the simultaneous operation of different types of instruments located in both high and mid-latitude regions in order to study the destruction processes as well as the evolution of the ozone layer during the period of the campaign. A description will be given here of a mobile ozone lidar instrument specially designed for operation during the EASOE campaign. This system, which performs ozone measurements in the 5 to 40 km altitude range was located in Sodankyla, Finland as part of the ELSA experiment which also includes operation of another multi-wavelength lidar designed for polar stratospheric cloud measurements.

  12. Linear fitting of multi-threshold counting data with a pixel-array detector for spectral X-ray imaging

    PubMed Central

    Muir, Ryan D.; Pogranichney, Nicholas R.; Muir, J. Lewis; Sullivan, Shane Z.; Battaile, Kevin P.; Mulichak, Anne M.; Toth, Scott J.; Keefe, Lisa J.; Simpson, Garth J.

    2014-01-01

    Experiments and modeling are described to perform spectral fitting of multi-threshold counting measurements on a pixel-array detector. An analytical model was developed for describing the probability density function of detected voltage in X-ray photon-counting arrays, utilizing fractional photon counting to account for edge/corner effects from voltage plumes that spread across multiple pixels. Each pixel was mathematically calibrated by fitting the detected voltage distributions to the model at both 13.5 keV and 15.0 keV X-ray energies. The model and established pixel responses were then exploited to statistically recover images of X-ray intensity as a function of X-ray energy in a simulated multi-wavelength and multi-counting threshold experiment. PMID:25178010

  13. A simple controller for bidimensional image detectors

    NASA Astrophysics Data System (ADS)

    Angeles, F.; Martínez, L. A.

    2012-07-01

    The increasing use of many and different kind of light detectors to acquire, monitor and control various aspects of the observation imposes the need to standardize the acquisition and processing of images and data. While scientific image acquisition systems usually include a complex controller, some less demanding subsystems require the development of electronics and software to read the image. Most of the times these image detectors are rather small and high speed is of no concern, so controllers need not to be fast; take for instance a telescope guider. With these directives in mind, in this work we present a very simple image acquisition system based on a Texas Instruments microcontroller of the family MSP430 and a serial static memory as a standard instrumentation starting for small image acquisition controllers.

  14. Cerenkov ring imaging detector development: Progress report

    SciTech Connect

    Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.; Ratcliff, B.

    1988-10-01

    We present recent progress on the construction and testing of the first drift boxes and single electron detectors as they come from the production line. These detectors will be used for particle identification using the Ring Imaging technique in the SLD experiment at SLAC. Various experimental results are presented, including single electron pulse height measurements as a function of gas gain, detector gating capability, uniformity of response across the wire plane, charge division performance of a single electron signal, average pulse shape and its comparison with predicted shape, and cross-talk. 14 refs., 11 figs.

  15. Stable multi-wavelength fiber laser with single-mode fiber in a Sagnac loop.

    PubMed

    Wang, Pinghe; Wang, Lei; Shi, Guohua; He, Tiejun; Li, Heping; Liu, Yong

    2016-04-20

    In this paper, we propose and experimentally demonstrate a stable multi-wavelength fiber laser at 1.5 μm with single-mode fiber (SMF). The Sagnac loop structure with a 48.6:51.4 coupler and 2 km SMF has an intensity-dependent loss, which contributes to suppress the mode competition in the cavity and leads to a steady multi-wavelength output. In the experiment, five stable lasing wavelengths are obtained with a pump power of 300 mW at 980 nm. The demonstrated multi-wavelength fiber laser has great potential for applications in optical communications and optical sensing systems. PMID:27140108

  16. Efficient nucleus detector in histopathology images.

    PubMed

    Vink, J P; Van Leeuwen, M B; Van Deurzen, C H M; De Haan, G

    2013-02-01

    In traditional cancer diagnosis, (histo)pathological images of biopsy samples are visually analysed by pathologists. However, this judgment is subjective and leads to variability among pathologists. Digital scanners may enable automated objective assessment, improved quality and reduced throughput time. Nucleus detection is seen as the corner stone for a range of applications in automated assessment of (histo)pathological images. In this paper, we propose an efficient nucleus detector designed with machine learning. We applied colour deconvolution to reconstruct each applied stain. Next, we constructed a large feature set and modified AdaBoost to create two detectors, focused on different characteristics in appearance of nuclei. The proposed modification of AdaBoost enables inclusion of the computational cost of each feature during selection, thus improving the computational efficiency of the resulting detectors. The outputs of the two detectors are merged by a globally optimal active contour algorithm to refine the border of the detected nuclei. With a detection rate of 95% (on average 58 incorrectly found objects per field-of-view) based on 51 field-of-view images of Her2 immunohistochemistry stained breast tissue and a complete analysis in 1 s per field-of-view, our nucleus detector shows good performance and could enable a range of applications in automated assessment of (histo)pathological images. PMID:23252774

  17. Imaging radiation detector with gain

    DOEpatents

    Morris, C.L.; Idzorek, G.C.; Atencio, L.G.

    1982-07-21

    A radiation imaging device which has application in x-ray imaging. The device can be utilized in CAT scanners and other devices which require high sensitivity and low x-ray fluxes. The device utilizes cumulative multiplication of charge carriers on the anode plane and the collection of positive ion charges to image the radiation intensity on the cathode plane. Parallel and orthogonal cathode wire arrays are disclosed as well as a two-dimensional grid pattern for collecting the positive ions on the cathode.

  18. Imaging radiation detector with gain

    DOEpatents

    Morris, Christopher L.; Idzorek, George C.; Atencio, Leroy G.

    1984-01-01

    A radiation imaging device which has application in x-ray imaging. The device can be utilized in CAT scanners and other devices which require high sensitivity and low x-ray fluxes. The device utilizes cumulative multiplication of charge carriers on the anode plane and the collection of positive ion charges to image the radiation intensity on the cathode plane. Parallel and orthogonal cathode wire arrays are disclosed as well as a two-dimensional grid pattern for collecting the positive ions on the cathode.

  19. Neutron beam imaging with GEM detectors

    NASA Astrophysics Data System (ADS)

    Albani, G.; Croci, G.; Cazzaniga, C.; Cavenago, M.; Claps, G.; Muraro, A.; Murtas, F.; Pasqualotto, R.; Perelli Cippo, E.; Rebai, M.; Tardocchi, M.; Gorini, G.

    2015-04-01

    Neutron GEM-based detectors represent a new frontier of devices in neutron physics applications where a very high neutron flux must be measured such as future fusion experiments (e.g. ITER Neutral beam Injector) and spallation sources (e.g. the European Spallation source). This kind of detectors can be properly adapted to be used both as beam monitors but also as neutron diffraction detectors that could represent a valid alternative for the 3He detectors replacement. Fast neutron GEM detectors (nGEM) feature a cathode composed by one layer of polyethylene and one of aluminium (neutron scattering on hydrogen generates protons that are detected in the gas) while thermal neutron GEM detectors (bGEM) are equipped with a borated aluminium cathode (charged particles are generated through the 10B(n,α)7Li reaction). GEM detectors can be realized in large area (1 m2) and their readout can be pixelated. Three different prototypes of nGEM and one prototype of bGEM detectors of different areas and equipped with different types of readout have been built and tested. All the detectors have been used to measure the fast and thermal neutron 2D beam image at the ISIS-VESUVIO beamline. The different kinds of readout patterns (different areas of the pixels) have been compared in similar conditions. All the detectors measured a width of the beam profile consitent with the expected one. The imaging property of each detector was then tested by inserting samples of different material and shape in the beam. All the samples were correctly reconstructed and the definition of the reconstruction depends on the type of readout anode. The fast neutron beam profile reconstruction was then compared to the one obtained by diamond detectors positioned on the same beamline while the thermal neutron one was compared to the imaged obtained by cadmium-coupled x-rays films. Also efficiency and the gamma background rejection have been determined. These prototypes represent the first step towards the

  20. Multi-Wavelength Based Optical Density Sensor for Autonomous Monitoring of Microalgae

    PubMed Central

    Jia, Fei; Kacira, Murat; Ogden, Kimberly L.

    2015-01-01

    A multi-wavelength based optical density sensor unit was designed, developed, and evaluated to monitor microalgae growth in real time. The system consisted of five main components including: (1) laser diode modules as light sources; (2) photodiodes as detectors; (3) driver circuit; (4) flow cell; and (5) sensor housing temperature controller. The sensor unit was designed to be integrated into any microalgae culture system for both real time and non-real time optical density measurements and algae growth monitoring applications. It was shown that the sensor unit was capable of monitoring the dynamics and physiological changes of the microalgae culture in real-time. Algae biomass concentration was accurately estimated with optical density measurements at 650, 685 and 780 nm wavelengths used by the sensor unit. The sensor unit was able to monitor cell concentration as high as 1.05 g·L−1 (1.51 × 108 cells·mL−1) during the culture growth without any sample preparation for the measurements. Since high cell concentrations do not need to be diluted using the sensor unit, the system has the potential to be used in industrial microalgae cultivation systems for real time monitoring and control applications that can lead to improved resource use efficiency. PMID:26364640

  1. Measurement of nonlinear refractive index based on multiple configuration of FBG in generating multi wavelength

    NASA Astrophysics Data System (ADS)

    Abdullah, Mohd Nizam; Shaari, Sahbudin; Ehsan, Abang Annuar; Menon, Susthitha; Zakaria, Osman

    2015-06-01

    A reliable method for measurement of the nonlinear refractive index through application of multi wavelength phenomenon. Multi wavelength realisation based on Erbium doped fibre laser (EDFL) is proposed and experimentally demonstrated. A combination of 15 m high efficiency Erbium doped fibre (EDF) and a 20 m Photonic Crystal Fibre (PCF) as main catalyst to suppress the homogenous broadening of EDF and to obtain highly stability of multi wavelength through insertion of a set of fibre Bragg gratings (FBGs) in the cavity. This PCF has zero dispersion of 1040 nm which mismatch from transmission window of 1550 nm. A reliable repeatability of multi wavelength based on multiple configuration of FBGs less than 0.2% obtained. This consistent results influence in determination of nonlinear refractive index by relation of four wave mixing (FWM).

  2. A multi-wavelength database of water vapor in planet-forming regions

    NASA Astrophysics Data System (ADS)

    Pontoppidan, Klaus

    The inner few astronomical units of gas-rich protoplanetary disk are environments characterized by a rich and active gaseous chemistry. Primitive material left over from the formation of our own Solar System has for a long time yielded tantalizing clues to a heterogenous nebula with intricate dynamical, thermal and chemical structure that ultimately led to a great diversity in the planets and planetesimals of the Solar System. The discovery of a rich chemistry in protoplanetary disks via a forest of strong 3-40 micron molecular emission lines (H2O, OH, CO2, HCN, C2H2,...) allows us for the first time to investigate chemical diversity in other planet-forming environmments (Salyk et al. 2008; Carr & Najita 2008). Further efforts, supported by the Origins program, has established that this molecular forest is seen in the disks surrounding most young solar- type stars (Pontoppidan et al. 2010). We propose a 3-year program to analyze our growing multi-wavelength database of observations of water, OH and organic molecules in the surfaces of protoplanetary disks. The database includes high (R~25,000-100,000) and medium resolution (R~600-3000) 3- 200 micron spectra from a wide range of facilities (Keck-NIRSPEC, VLT-CRIRES, Spitzer-IRS, VLT-VISIR, Gemini-Michelle and Herschel-PACS). Our previous efforts have focused on demonstrating feasibility for observing water and other molecules in planet-forming regions, building statistics to show that the molecular forest is ubiquitous in disks around low-mass and solar-type stars and taking the first steps in understanding the implied chemical abundances. Now, as the next logical step, we will combine multi- wavelength data from our unique multi-wavelength database to map the radial distribution of, in particular, water and its derivatives. 1) Â We will use both line profile information from the high-resolution spectra, as well as line strengths, from a combination of high and low temperature lines to constrain the radial

  3. A multi-wavelength database of water vapor in planet-forming regions

    NASA Astrophysics Data System (ADS)

    Pontoppidan, Klaus

    The inner few astronomical units of gas-rich protoplanetary disk are environments characterized by a rich and active gaseous chemistry. Primitive material left over from the formation of our own Solar System has for a long time yielded tantalizing clues to a heterogenous nebula with intricate dynamical, thermal and chemical structure that ultimately led to a great diversity in the planets and planetesimals of the Solar System. The discovery of a rich chemistry in protoplanetary disks via a forest of strong 3-40 micron molecular emission lines (H2O, OH, CO2, HCN, C2H2,...) allows us for the first time to investigate chemical diversity in other planet-forming environmments (Salyk et al. 2008; Carr & Najita 2008). Further efforts, supported by the Origins program, has established that this molecular forest is seen in the disks surrounding most young solar- type stars (Pontoppidan et al. 2010). We propose a 3-year program to analyze our growing multi-wavelength database of observations of water, OH and organic molecules in the surfaces of protoplanetary disks. The database includes high (R~25,000-100,000) and medium resolution (R~600-3000) 3- 200 micron spectra from a wide range of facilities (Keck-NIRSPEC, VLT-CRIRES, Spitzer-IRS, VLT-VISIR, Gemini-Michelle and Herschel-PACS). Our previous efforts have focused on demonstrating feasibility for observing water and other molecules in planet-forming regions, building statistics to show that the molecular forest is ubiquitous in disks around low-mass and solar-type stars and taking the first steps in understanding the implied chemical abundances. Now, as the next logical step, we will combine multi- wavelength data from our unique multi-wavelength database to map the radial distribution of, in particular, water and its derivatives. 1) We will use both line profile information from the high-resolution spectra, as well as line strengths, from a combination of high and low temperature lines to constrain the radial abundance

  4. Programmable illumination and high-speed, multi-wavelength, confocal microscopy using a digital micromirror.

    PubMed

    Martial, Franck P; Hartell, Nicholas A

    2012-01-01

    Confocal microscopy is routinely used for high-resolution fluorescence imaging of biological specimens. Most standard confocal systems scan a laser across a specimen and collect emitted light passing through a single pinhole to produce an optical section of the sample. Sequential scanning on a point-by-point basis limits the speed of image acquisition and even the fastest commercial instruments struggle to resolve the temporal dynamics of rapid cellular events such as calcium signals. Various approaches have been introduced that increase the speed of confocal imaging. Nipkov disk microscopes, for example, use arrays of pinholes or slits on a spinning disk to achieve parallel scanning which significantly increases the speed of acquisition. Here we report the development of a microscope module that utilises a digital micromirror device as a spatial light modulator to provide programmable confocal optical sectioning with a single camera, at high spatial and axial resolution at speeds limited by the frame rate of the camera. The digital micromirror acts as a solid state Nipkov disk but with the added ability to change the pinholes size and separation and to control the light intensity on a mirror-by-mirror basis. The use of an arrangement of concave and convex mirrors in the emission pathway instead of lenses overcomes the astigmatism inherent with DMD devices, increases light collection efficiency and ensures image collection is achromatic so that images are perfectly aligned at different wavelengths. Combined with non-laser light sources, this allows low cost, high-speed, multi-wavelength image acquisition without the need for complex wavelength-dependent image alignment. The micromirror can also be used for programmable illumination allowing spatially defined photoactivation of fluorescent proteins. We demonstrate the use of this system for high-speed calcium imaging using both a single wavelength calcium indicator and a genetically encoded, ratiometric, calcium

  5. Optical Ranicon detectors for photon counting imaging.

    NASA Astrophysics Data System (ADS)

    Clampin, Mark; Crocker, Jim; Paresce, Francesco; Rafal, Marc

    1988-08-01

    The design and development of two detectors, known as Ranicon and advanced Ranicon, for optical photon counting imaging on ground-based telescopes are discussed. The proximity focusing, microchannel-plate stack, resistive anode, and signal processing characteristics are described. The theory behind the overall resolution of the Ranicon system is reviewed. Resolution measurements for the instruments are reported and discussed.

  6. X-ray detectors in medical imaging

    NASA Astrophysics Data System (ADS)

    Spahn, Martin

    2013-12-01

    Healthcare systems are subject to continuous adaptation, following trends such as the change of demographic structures, the rise of life-style related and chronic diseases, and the need for efficient and outcome-oriented procedures. This also influences the design of new imaging systems as well as their components. The applications of X-ray imaging in the medical field are manifold and have led to dedicated modalities supporting specific imaging requirements, for example in computed tomography (CT), radiography, angiography, surgery or mammography, delivering projection or volumetric imaging data. Depending on the clinical needs, some X-ray systems enable diagnostic imaging while others support interventional procedures. X-ray detector design requirements for the different medical applications can vary strongly with respect to size and shape, spatial resolution, frame rates and X-ray flux, among others. Today, integrating X-ray detectors are in common use. They are predominantly based on scintillators (e.g. CsI or Gd2O2S) and arrays of photodiodes made from crystalline silicon (Si) or amorphous silicon (a-Si) or they employ semiconductors (e.g. Se) with active a-Si readout matrices. Ongoing and future developments of X-ray detectors will include optimization of current state-of-the-art integrating detectors in terms of performance and cost, will enable the usage of large size CMOS-based detectors, and may facilitate photon counting techniques with the potential to further enhance performance characteristics and foster the prospect of new clinical applications.

  7. Automated lesion detectors in retinal fundus images.

    PubMed

    Figueiredo, I N; Kumar, S; Oliveira, C M; Ramos, J D; Engquist, B

    2015-11-01

    Diabetic retinopathy (DR) is a sight-threatening condition occurring in persons with diabetes, which causes progressive damage to the retina. The early detection and diagnosis of DR is vital for saving the vision of diabetic persons. The early signs of DR which appear on the surface of the retina are the dark lesions such as microaneurysms (MAs) and hemorrhages (HEMs), and bright lesions (BLs) such as exudates. In this paper, we propose a novel automated system for the detection and diagnosis of these retinal lesions by processing retinal fundus images. We devise appropriate binary classifiers for these three different types of lesions. Some novel contextual/numerical features are derived, for each lesion type, depending on its inherent properties. This is performed by analysing several wavelet bands (resulting from the isotropic undecimated wavelet transform decomposition of the retinal image green channel) and by using an appropriate combination of Hessian multiscale analysis, variational segmentation and cartoon+texture decomposition. The proposed methodology has been validated on several medical datasets, with a total of 45,770 images, using standard performance measures such as sensitivity and specificity. The individual performance, per frame, of the MA detector is 93% sensitivity and 89% specificity, of the HEM detector is 86% sensitivity and 90% specificity, and of the BL detector is 90% sensitivity and 97% specificity. Regarding the collective performance of these binary detectors, as an automated screening system for DR (meaning that a patient is considered to have DR if it is a positive patient for at least one of the detectors) it achieves an average 95-100% of sensitivity and 70% of specificity at a per patient basis. Furthermore, evaluation conducted on publicly available datasets, for comparison with other existing techniques, shows the promising potential of the proposed detectors. PMID:26378502

  8. The Ring Imaging Cherenkov detectors of DELPHI

    SciTech Connect

    Adam, W.; Albrecht, E.; Allen, D.

    1995-08-01

    A Ring Imaging Cherenkov (RICH) detector system has been built and is now in full operation within the DELPHI experiment. Large data samples of Z{sup 0} decays are being collected with good resolution on the observed Cherenkov angles. Several studies of Z{sup 0} decays using the RICH have already been performed on limited samples. Disturbance of the detector operation caused by shrinkage of polymeric construction materials and by migration of radiator substance is reported. These effects have been counteracted and do not endanger the quality of the data.

  9. Dynamic cardiac volume imaging using area detectors

    NASA Astrophysics Data System (ADS)

    Bruder, Herbert; Hoelzel, Arne; Stierstorfer, Karl; Rauscher, Annabella; Flohr, Thomas

    2003-05-01

    We present a reconstruction scheme for dynamic cardiac volume imaging using Area Detector Computed Tomography (CT) named Multi-Sector Cardiac Volume Reconstruction (MCVR) which is based on a 3D-backprojection of the Feldkamp-type. It is intended for circular scanning using area detectors covering the whole heart volume, but the method can easily be extended to cardiac spiral imaging using multi-slice CT. In cardiac imaging with multi-slice CT continuous data acquisition combined with the parallel recording of the patient's ECG enables retrospective gating of data segments for image reconstruction. Using consecutive heart cycles MCVR identifies complementary and time consistent projection data segments <= π using temporal information of the ECG. After a row by row parallel rebinning and temporal rebinning the projection data have to be filtered using conventional convolution kernels and finally reconstructed to image space using a 3D-backprojection. A dynamic anthropomorphic computer model of the human heart was developed in order to validate the MCVR approach. A 256-slice detector system with 0.5mm slice collimation was simulated operating in a circular scanning mode at a gantry rotation time of 330ms and compared to state-of-the-art 16-slice technology. At enddiastole the coronary anatomy can be visualized with excellent image quality. Although an area detector with large cone angling covering the entire heart volume was used no cone-artifacts could be observed. Using a 2-sector approach a nearly motion free 3D visualization of the heart chambers was obtained even at endsystole.

  10. The new MQ/AAO/Strasbourg multi-wavelength and spectroscopic PNe database: MASPN

    NASA Astrophysics Data System (ADS)

    Parker, Quentin Andrew; Bojicic, Ivan; Frew, David; Acker, Agnes; Ochsenbein, Francois; MASPN Database Team

    2015-01-01

    We are in a new golden age of PN discovery. This is thanks in particular to high sensitivity, wide-field, narrow-band surveys of the Galactic plane undertaken on the UKST in Australia and the Isaac Newton telescope on La Palma. Together these telescopes and their H-alpha surveys have provided very significant Planetary Nebulae (PNe) discoveries that have more than doubled the totals accrued by all telescopes over the previous 250 years. However, these PNe are not simply more of the same found in previous catalogues. Most new PNe are more obscured, evolved and of lower surface brightness than previous compilations while others are faint but compact and more distant. This has required an extensive and time-consuming programme of spectroscopic confirmation on a variety of 2m and 4m telescopes that is now largely complete. The scope of any future large-scale PNe studies, particularly those of a statistical nature or undertaken to understand true PNe diversity and evolution should now reflect this fresh PN population landscape of the combined sample of ~3500 Galactic PNe now available. Such studies should be coloured and nuanced by these recent major discoveries and the massive, high sensitivity, high resolution, multi-wavelength imaging surveys now available across much of the electromagnetic spectrum.Following this motivation we provide, for the first time, an accessible, reliable, on-line "one-stop" SQL database for essential, up-to date information for all known Galactic PN. We have attempted to: i) Reliably remove the many PN mimics/false ID's that have biased previous compilations and subsequent studies; ii) Provide accurate, updated positions, sizes, morphologies, radial velocities, fluxes, multi-wavelength imagery and spectroscopy; iii) Link to CDS/Vizier and hence provide archival history for each object; iv) Provide an interface to sift, select, browse, collate, investigate, download and visualise the complete currently known Galactic PNe diaspora and v

  11. Characterisation of a track structure imaging detector.

    PubMed

    Casiraghi, M; Bashkirov, V A; Hurley, R F; Schulte, R W

    2015-09-01

    The spatial distribution of radiation-induced ionisations in sub-cellular structures plays an important role in the initial formation of radiation damage to biological tissues. Using the nanodosimetry approach, physical characteristics of the track structure can be measured and correlated to DNA damage. In this work, a novel nanodosimeter is presented, which detects positive ions produced by radiation interacting with a gas-sensitive volume in order to obtain a high resolution image of the radiation track structure. The characterisation of the detector prototype was performed and different configurations of the device were tested by varying the detector cathode material and the working gas. Preliminary results show that the ionisation cluster size distribution can be obtained with this approach. Further work is planned to improve the detector efficiency in order to register the complete three-dimensional track structure of ionising radiation. PMID:25877534

  12. The SORDS trimodal imager detector arrays

    NASA Astrophysics Data System (ADS)

    Wakeford, Daniel; Andrews, H. R.; Clifford, E. T. H.; Li, Liqian; Bray, Nick; Locklin, Darren; Hynes, Michael V.; Toolin, Maurice; Harris, Bernard; McElroy, John; Wallace, Mark; Lanza, Richard

    2009-05-01

    The Raytheon Trimodal Imager (TMI) uses coded aperture and Compton imaging technologies as well as the nonimaging shadow technology to locate an SNM or radiological threat in the presence of background. The heart of the TMI is two arrays of NaI crystals. The front array serves as both a coded aperture and the first scatterer for Compton imaging. It is made of 35 5x5x2" crystals with specially designed low profile PMTs. The back array is made of 30 2.5x3x24" position-sensitive crystals which are read out at both ends. These crystals are specially treated to provide the required position resolution at the best possible energy resolution. Both arrays of detectors are supported by aluminum superstructures. These have been efficiently designed to allow a wide field of view and to provide adequate support to the crystals to permit use of the TMI as a vehicle-mounted, field-deployable system. Each PMT has a locally mounted high-voltage supply that is remotely controlled. Each detector is connected to a dedicated FPGA which performs automated gain alignment and energy calibration, event timing and diagnostic health checking. Data are streamed, eventby- event, from each of the 65 detector FPGAs to one master FPGA. The master FPGA acts both as a synchronization clock, and as an event sorting unit. Event sorting involves stamping events as singles or as coincidences, based on the approximately instantaneous detector hit pattern. Coincidence determination by the master FPGA provides a pre-sorting for the events that will ultimately be used in the Compton imaging and coded aperture imaging algorithms. All data acquisition electronics have been custom designed for the TMI.

  13. Lensless phase microscopy and diffraction tomography with multi-angle and multi-wavelength illuminations using a LED matrix.

    PubMed

    Zuo, Chao; Sun, Jiasong; Zhang, Jialin; Hu, Yan; Chen, Qian

    2015-06-01

    We demonstrate lensless quantitative phase microscopy and diffraction tomography based on a compact on-chip platform, using only a CMOS image sensor and a programmable color LED matrix. Based on the multi-wavelength phase retrieval and multi-angle illumination diffraction tomography, this platform offers high quality, depth resolved images with a lateral resolution of 3.72μm and an axial resolution of 5μm, across a wide field-of-view of 24mm2. We experimentally demonstrate the success of our method by imaging cheek cells, micro-beads, and fertilized eggs of Parascaris equorum. Such high-throughput and miniaturized imaging device can provide a cost-effective tool for telemedicine applications and point-of-care diagnostics in resource-limited environments. PMID:26072796

  14. A new multi-wavelength solar telescope: Optical and Near-infrared Solar Eruption Tracer (ONSET)

    NASA Astrophysics Data System (ADS)

    Fang, Cheng; Chen, Peng-Fei; Li, Zhen; Ding, Ming-De; Dai, Yu; Zhang, Xiao-Yu; Mao, Wei-Jun; Zhang, Jun-Ping; Li, Ting; Liang, Yong-Jun; Lu, Hai-Tian

    2013-12-01

    A new multi-wavelength solar telescope, the Optical and Near-infrared Solar Eruption Tracer (ONSET) of Nanjing University, has been constructed. It was fabricated at the Nanjing Institute of Astronomical Optics & Technology, and the operation is jointly administered with Yunnan Astronomical Observatory. ONSET is able to observe the Sun in three wavelength windows: He I 10830 Å, Hα and white-light at 3600 Å and 4250 Å, which are selected in order to simultaneously record the dynamics of the corona, chromosphere and photosphere respectively. Full-disk or partial-disk solar images with a field of 10' at three wavelengths can be obtained nearly simultaneously. It is designed to trace solar eruptions with high spatial and temporal resolutions. This telescope was installed at a new solar observing site near Fuxian Lake in Yunnan Province, southwest China. The site is located at E102N24, with an altitude of 1722 m. The seeing is stable and has high quality. We give a brief description of the scientific objectives and the basic structure of ONSET. Some preliminary results are also presented.

  15. Multi-wavelength Observations of Cyg X-3 During a Hard X-ray Flare

    NASA Astrophysics Data System (ADS)

    Perkins, Jeremy S.; Matthews, N. K.; VERITAS Collaboration

    2013-04-01

    We present the results of multi-wavelength observations of the microquasar Cygnus X-3 which was detected by the Burst Alert Telescope (BAT) onboard the Swift observatory to be in a hard X-ray (10-150 keV) flaring state on March 23, 2012. Since the VERITAS collaboration has initiated a plan to perform follow-up observations of hard X-ray transients detected by the BAT, this event prompted observations with the VERITAS array of imaging atmospheric Cherenkov telescopes on the nights of March 24 and 27, 2012. A significant very high energy (VHE; E>100GeV) signal was not seen from the micro quasar. In addition to the BAT and VERITAS observations, we will present the results of an analysis of Fermi LAT data in the 200 - 300,000 MeV band from the flaring period. Although the exact physics are currently unclear, observations over the entire electromagnetic spectrum can provide insight to the physical phenomena producing the flares.

  16. The XCat-DB: A Multi-wavelength View on the 2XMMi Catalogue

    NASA Astrophysics Data System (ADS)

    Motch, C.; Michel, L.; Pineau, F.-X.

    2009-09-01

    The XCat-DB hosts the newly-released 2XMMi catalogue together with many associated products such as X-ray images, spectra, time series and optical finding charts. One of its innovative features is to give access to cross-correlations with ˜ 200 archival catalogues. For the most important ones (SDSS R6, USNOB-1 and 2MASS), a specific likelihood ratio algorithm has been used to compute identification probabilities with entries in these catalogues. The XCat-DB is meant to be a ``discovery tool'' facilitating the identification of individual X-ray sources, thanks to locally-stored information and to direct VO access. Other important science goals are the creation of large source samples sharing homogeneous multi-wavelength properties and the search for interesting outliers. The current interface offers simple source selection and easy browsing through 2XMMi entries, associated data files and proposed X-ray source counterparts. Based on Saada, correlation information are stored in persistent relationships allowing fast query execution and navigation across the heterogeneous data sets. More complex queries mixing constraints on X-ray properties, on the existence or not of a possible counterpart in an archival catalogue and on the probability of association can also be made. The database can be accessed at XCat-DB (http://xcatdb.u-strasbg.fr/2xmmi/).

  17. Multispectral imaging with type II superlattice detectors

    NASA Astrophysics Data System (ADS)

    Ariyawansa, Gamini; Duran, Joshua M.; Grupen, Matt; Scheihing, John E.; Nelson, Thomas R.; Eismann, Michael T.

    2012-06-01

    Infrared (IR) focal plane arrays (FPAs) with multispectral detector elements promise significant advantages for airborne threat warning, surveillance, and targeting applications. At present, the use of type II superlattice (T2SL) structures based on the 6.1Å-family materials (InAs, GaSb, and AlSb) has become an area of interest for developing IR detectors and their FPAs. The ability to vary the bandgap in the IR range, suppression of Auger processes, prospective reduction of Shockley-Read-Hall centers by improved material growth capabilities, and the material stability are a few reasons for the predicted dominance of the T2SL technology over presently leading HgCdTe and quantum well technologies. The focus of the work reported here is on the development of T2SL based dual-band IR detectors and their applicability for multispectral imaging. A new NpBPN detector designed for the detection of IR in the 3-5 and 8-12 μm atmospheric windows is presented; comparing its advantages over other T2SL based approaches. One of the key challenges of the T2SL dual-band detectors is the spectral crosstalk associated with the LWIR band. The properties of the state-of-the-art T2SLs (i.e., absorption coefficient, minority carrier lifetime and mobility, etc.) and the present growth limitations that impact spectral crosstalk are discussed.

  18. Continuous Wave Spectroscopy with Diffusion Theory for Quantification of Optical Properties: Comparison Between Multi-distance and Multi-wavelength Data Fitting Methods.

    PubMed

    Lin, Yung-Chi; Lin, Zhi-Fong; Nioka, Shoko; Chen, Li-Hsin; Tseng, Sheng-Hao; Chung, Pau-Choo

    2016-01-01

    Typically, continuous wave spectroscopy (CWS) can be used to accurately quantify biological tissue optical properties (μ a and μ s ') by employing the diffuse reflectance information acquired at multiple source-detector separations (multi-distance). On the other hand, sample optical properties can also be obtained by fitting multi-wavelength light reflectance acquired at a single source detector separation to the diffusion theory equation. To date, multi-wavelength and multi-distance methods have not yet been rigorously compared for their accuracy in quantification of the sample optical properties. In this investigation, we compared the accuracy of the two above-mentioned quantifying methods in the optical properties recovery. The liquid phantoms had μ a between 0.004 and 0.011 mm(-1) and μ s ' between 0.55 and 1.07 mm(-1) whose optical properties mimic the human breast. Multi-distance data and multi-wavelength data were fitted to the same diffusion equation for consistency. The difference between benchmark μ a and μ s ' and the fitted results, ΔError (ΔE) was used to evaluate the accuracy of the two methods. The results showed that either method yielded ΔE within 15-30 % when values were within certain limits to standard values applicable to μ s ' and μ a for human adipose tissue. Both methods showed no significant differences in ΔE values. Our results suggest that both multi-distance and multi-wavelength methods can yield similar reasonable optical properties in biological tissue with a proper calibration. PMID:27526161

  19. Cerenkov ring imaging detector development at SLAC

    SciTech Connect

    Williams, S.H.

    1984-06-01

    The imaging of Cerenkov light on to photosensitive detectors promises to be a powerful technique for identifying particles in colliding beam spectrometers. Toward this end two and three dimensional imaging photon detectors are being developed at SLAC. The present techniques involve photon conversion using easily ionized exotic chemicals like tetrakisdimethyl-amino-ethylene (TMAE) in a drift and amplifying gas mixture of methane and isobutane. Single photoelectrons from Cerenkov light are currently being drifted 20 cm and a new device under study will be used to study drifting up to 80 cm along a magnetic field. A short description of a large device currently being designed for the SLD spectrometer at the Stanford Linear Collider will be given.

  20. Multi-wavelength laser tuning based on cholesteric liquid crystals with nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Sheng-Chieh; Lin, Jia-De; Lee, Chia-Rong; Hwang, Shug-June

    2016-04-01

    A controllable multi-wavelength laser from a dye-doped cholesteric liquid crystal (DDCLC) cell is demonstrated by incorporating self-assembled polyhedral oligomeric silsesquioxane (POSS) nanoparticles (NPs). Multi-wavelength lasing emission is achieved by formation of multiple planar domains; this formation is dominantly influenced by the vertical alignment of NP clusters adsorbed on the substrate surface through a rapid thermal annealing process. The multi-wavelength lasing peaks are generated through the resultant effect of multiple longitudinal resonant modes of a Fabry-Pérot etalon between the cell substrates and the amplification of fluorescence photons with the resonant wavelengths within the broadening long-wavelength edge of the reflection band of the multi-domain CLC. The amount of multi-wavelength lasing peaks can be controlled by changing the POSS NP concentration and the cooling rate of the cell. Furthermore, thermo-reversible control of the multi-wavelength lasing emission can be attained by controlling the thermally induced phase separation process of the POSS/DDCLC cell via a heating/cooling cyclic process.

  1. Multispectral imaging using a single bucket detector.

    PubMed

    Bian, Liheng; Suo, Jinli; Situ, Guohai; Li, Ziwei; Fan, Jingtao; Chen, Feng; Dai, Qionghai

    2016-01-01

    Existing multispectral imagers mostly use available array sensors to separately measure 2D data slices in a 3D spatial-spectral data cube. Thus they suffer from low photon efficiency, limited spectrum range and high cost. To address these issues, we propose to conduct multispectral imaging using a single bucket detector, to take full advantage of its high sensitivity, wide spectrum range, low cost, small size and light weight. Technically, utilizing the detector's fast response, a scene's 3D spatial-spectral information is multiplexed into a dense 1D measurement sequence and then demultiplexed computationally under the single pixel imaging scheme. A proof-of-concept setup is built to capture multispectral data of 64 pixels × 64 pixels × 10 wavelength bands ranging from 450 nm to 650 nm, with the acquisition time being 1 minute. The imaging scheme holds great potentials for various low light and airborne applications, and can be easily manufactured as production-volume portable multispectral imagers. PMID:27103168

  2. Multi-wavelength solar activity complexes evolution from Solar Dynamic Observatory (SDO)

    NASA Astrophysics Data System (ADS)

    Korolkova, Olga; Benevolenskaya, Elena

    The main problem of the solar physics is to understand a nature of the solar magnetic activity. New space missions and background observations provide us by data describing solar activity with a good space and time resolution. Space missions data observe the solar activity in multi-wavelength emissions come from photosphere to corona. The complex of the solar activity has roots in inte-rior and extends to the solar corona. Thus, modern data give an opportunity to study the activity on the Sun at different levels simultaneously. Solar Dynamics Observatory (SDO) [1] which launched at the beginning of 2010, looks at Sun in different wavelengths such as coronal lines 171Å & 335Å. Also SDO measures photospheric magnetic flux (line-of-sight component of the magnetic field strength) and gives images in continuum. We have studied a stable complexes of the solar activity (about 30 com-plexes) during 6 hours from 10 March 2013 to 14 October 2013 using 720s ca-dence of HMI (Helioseismic and Magnetic Imager) [2] and AIA (Atmospheric Imaging Assembly) [3] instruments of SDO. We have found a good relationship between the magnetic flux and coronal emissions. Here we discuss properties of the complexes in the different levels from photosphere to corona. References 1. W. Dean Pesnell, B.J. Thompson, P.C. Chamberlin // Solar Phys., v. 275, p. 3-15, (2012). 2. P.H. Scherrer, J. Schou, R.I. Bush et al. // Solar Phys., v. 275, p. 207-227, (2012). 3. James R. Lemen • Alan M. Title • David J. Akin et al. // Solar Phys., v. 275, p. 17-40, (2012).

  3. Thermal characteristics of multi-wavelength emission during a B8.3 flare occurred on July 04, 2009

    NASA Astrophysics Data System (ADS)

    Awasthi, Arun Kumar; Sylwester, Barbara; Sylwester, Janusz; Jain, Rajmal

    2015-08-01

    We explore the temporal evolution of flare plasma parameters including temperature (T) - differential emission measure (DEM) relationship by analyzing high spectral and temporal cadence X-ray emission in 1.2-20 keV energy band, recorded by SphinX (Polish) and Solar X-ray Spectrometer (SOXS; Indian) instruments, during a B8.3 flare which occurred on July 04, 2009. SphinX records X-ray emission in 1.2-15 keV energy band with the temporal and spectral cadence as good as 6µs and 0.4 keV, respectively. On the other hand, SOXS provides X-ray observations in 4-25 keV energy band with the temporal and spectral resolution of 3s and 0.7 keV, respectively. In addition, we integrate co-temporal EUV line emission in 171, 194 and 284 angstrom obtained from STEREO mission in order to explore low-temperature response to the flare emission. In order to fit observed evolution of multi-wavelength emission during the flare, we incorporate multi-Gaussian and well-established Withbroe - Sylwester maximum likelihood DEM inversion algorithms. Thermal energetics are also estimated using geometrically corrected flaring loop structure obtained through EUV images of the active region from STEREO twin satellites. In addition, we also study the trigger and energy release scenario of this low-intensity class flare in terms of magnetic field as well as multi-wavelength emission.

  4. MULTI-WAVELENGTH AFTERGLOWS OF FAST RADIO BURSTS

    SciTech Connect

    Yi, Shuang-Xi; Gao, He; Zhang, Bing

    2014-09-01

    The physical origin of fast radio bursts (FRBs) is unknown. Detecting electromagnetic counterparts to FRBs in other wavelengths is essential to measure their distances and to determine their physical origin. Assuming that at least some of them are of cosmological origin, we calculate their afterglow light curves in multiple wavelengths (X-rays, optical, and radio) by assuming a range of total kinetic energies and redshifts. We focus on forward shock emission, but also consider the possibility that some of the FRBs might have bright reverse shock emission. In general, FRB afterglows are too faint to be detected by current detectors. Only if an FRB has a very low radiative efficiency in radio (hence, a very large kinetic energy), and when it is close enough to observe can its afterglow be detected in the optical and radio bands. We discuss observational strategies for detecting these faint afterglows using future telescopes such as Large Synoptic Survey Telescope and Expanded Very Large Array.

  5. Multi-wavelength Observations of Solar Active Region NOAA 7154

    NASA Technical Reports Server (NTRS)

    Bruner, M. E.; Nitta, N. V.; Frank. Z. A.; Dame, L.; Suematsu, Y.

    2000-01-01

    We report on observations of a solar active region in May 1992 by the Solar Plasma Diagnostic Experiment (SPDE) in coordination with the Yohkoh satellite (producing soft X-ray images) and ground-based observatories (producing photospheric magnetograms and various filtergrams including those at the CN 3883 A line). The main focus is a study of the physical conditions of hot (T is approximately greater than 3 MK) coronal loops at their foot-points. The coronal part of the loops is fuzzy but what appear to be their footpoints in the transition region down to the photosphere are compact. Despite the morphological similarities, the footpoint emission at 10(exp 5) K is not quantitatively correlated with that at approximately 300 km above the tau (sub 5000) = 1 level, suggesting that the heat transport and therefore magnetic field topology in the intermediate layer is complicated. High resolution imaging observations with continuous temperature coverage are crucially needed.

  6. Advanced digital detectors for neutron imaging.

    SciTech Connect

    Doty, F. Patrick

    2003-12-01

    Neutron interrogation provides unique information valuable for Nonproliferation & Materials Control and other important applications including medicine, airport security, protein crystallography, and corrosion detection. Neutrons probe deep inside massive objects to detect small defects and chemical composition, even through high atomic number materials such as lead. However, current detectors are bulky gas-filled tubes or scintillator/PM tubes, which severely limit many applications. Therefore this project was undertaken to develop new semiconductor radiation detection materials to develop the first direct digital imaging detectors for neutrons. The approach relied on new discovery and characterization of new solid-state sensor materials which convert neutrons directly to electronic signals via reactions BlO(n,a)Li7 and Li6(n,a)T.

  7. A photonic digital-to-analog conversion based on multi-wavelength sampling

    NASA Astrophysics Data System (ADS)

    Zhang, Yuancheng; Zhang, Hongming; Peng, Yue; Yao, Minyu

    2008-11-01

    A novel digital-to-analog converter based on multi-wavelength pulse source is proposed and primarily demonstrated by experiment. The multi-wavelength pulse train which has been pretreated is separated in time domain through dispersion. The pulse of different wavelength corresponds to the input digital data. Only one electro-optical modulator is needed in the scheme. In the primary experiment, a 3-bit photonic digital-to-analog converter with a sample rate of 2.5 Gb/s is realized. The scheme is simple and compact compared with the scheme using multiple electro-optical modulators.

  8. Quantum dot SOA/silicon external cavity multi-wavelength laser.

    PubMed

    Zhang, Yi; Yang, Shuyu; Zhu, Xiaoliang; Li, Qi; Guan, Hang; Magill, Peter; Bergman, Keren; Baehr-Jones, Thomas; Hochberg, Michael

    2015-02-23

    We report a hybrid integrated external cavity, multi-wavelength laser for high-capacity data transmission operating near 1310 nm. This is the first demonstration of a single cavity multi-wavelength laser in silicon to our knowledge. The device consists of a quantum dot reflective semiconductor optical amplifier and a silicon-on-insulator chip with a Sagnac loop mirror and microring wavelength filter. We show four major lasing peaks from a single cavity with less than 3 dB power non-uniformity and demonstrate error-free 4 × 10 Gb/s data transmission. PMID:25836504

  9. Multi-Wavelength Near Infrared Observations of Marum and Yasur Volcanoes, Vanuatu

    NASA Astrophysics Data System (ADS)

    Howell, Robert R.; Radebaugh, Jani; Lopes, Rosaly M.; Lorenz, Ralph D.; Turtle, Elizabeth P.

    2014-11-01

    To help understand and test models of thermal emission from planetary volcanoes, we obtained in May 2014 a variety of near-infrared observations of the very active Marum lava lake on Ambrym, Vanuatu, as well as the Strombolian activity at Yasur on Tanna. Our observations include high resolution images and movies made with standard and modified cameras and camcorders. In addition, to test the planetary emission models, which typically rely on multi-wavelength observations, we developed a small inexpensive prototype imager named "Kerby", which consists of three simultaneously active near-infrared cameras operating at 0.860, 0.775, and 0.675 microns, as well as a fourth visible wavelength RGB camera. This prototype is based on the Raspberry Pi and Pi-NoIR cameras. It can record full high definition video, and is light enough to be carried by backpack and run from batteries. To date we have concentrated on the analysis of the Marum data. During our observations of the 40 m diameter lava lake, convection was so vigorous that areas of thin crust formed only intermittently and persisted for tens of seconds to a few minutes at most. The convection pattern primarily consisted of two upwelling centers located about 8 m in from the margins on opposite sides of the lake. Horizontal velocities away from the upwelling centers were approximately 4 m/s. A hot bright margin roughly 0.4 m wide frequently formed around parts of the lake perimeter. We are in the process of establishing the absolute photometry calibration to obtain temperatures, temperature distributions, and magma cooling rates.

  10. Multi-Wavelength Views of Protostars in IC 1396

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site] Click on individual images below for larger view

    [figure removed for brevity, see original site]

    [figure removed for brevity, see original site]

    [figure removed for brevity, see original site]

    NASA's Spitzer Space Telescope has captured a glowing stellar nursery within a dark globule that is opaque at visible light. These new images pierce through the obscuration to reveal the birth of new protostars, or embryonic stars, and young stars never before seen.

    The Elephant's Trunk Nebula is an elongated dark globule within the emission nebula IC 1396 in the constellation of Cepheus. Located at a distance of 2,450 light-years, the globule is a condensation of dense gas that is barely surviving the strong ionizing radiation from a nearby massive star. The globule is being compressed by the surrounding ionized gas.

    The large composite image above is a product of combining data from the observatory's multiband imaging photometer and the infrared array camera. The thermal emission at 24 microns measured by the photometer (red) is combined with near-infrared emission from the camera at 3.6/4.5 microns (blue) and from 5.8/8.0 microns (green). The colors of the diffuse emission and filaments vary, and are a combination of molecular hydrogen (which tends to be green) and polycyclic aromatic hydrocarbon (brown) emissions.

    Within the globule, a half dozen newly discovered protostars, or embryonic stars, are easily discernible as the bright red-tinted objects, mostly along the southern rim of the globule. These were previously undetected at visible wavelengths due to obscuration by the thick cloud ('globule body') and by dust surrounding the newly forming stars. The newborn stars form in the dense gas because of compression by the wind and radiation from a nearby massive star (located outside the field of view to the left). The winds from this unseen star are also responsible for producing the

  11. Imaging the sensitivity inhomogeneities ofdiamond detectors

    NASA Astrophysics Data System (ADS)

    Barrett, R.; Tromson, D.; Hainaut, O.; Amosov, V. N.; Bergonzo, P.

    2003-03-01

    Diamond is a semiconducting material which can withstand high temperatures, a wide range of corrosive environments and exhibits high radiation hardness. This combination of properties makes it extremely attractive for use as photon and particle detectors. The ESRF ID21 SXM has been used to image the spatial variations of detector sensitivity over a range of both natural and Chemical Vapour Deposited (CVD) diamond devices. The measurements are performed by mapping the photon-induced current flow of the biased detectors. Evaluation of the sensitivity inhomogeneities are of dual interest; For detection applications involving relatively small beams it is important that the device response be as uniform as possible. Furthermore, from a fundamental aspect, the understanding of the origin of the sensitivity variations can be a route, for example in CVD materials, to modifying the growth and processing parameters in order to produce improved devices. This paper demonstrates an application of alternative detection modes in X-ray microscopy for a problem of technological interest. Moreover, it shows how the flexible control of the primary X-ray penetration depth by varying the probe energy permits an evaluation of the relative influence of the surface and bulk material.

  12. Multi-wavelength measurement of cytochrome oxidase and water in biomedical tissues using optical topography system

    NASA Astrophysics Data System (ADS)

    Funane, Tsukasa; Atsumori, Hirokazu; Sato, Hiroki; Kiguchi, Masashi; Maki, Atsushi

    2009-02-01

    Optical topography is a brain function imaging technology based on near-infrared spectroscopy, whereby changes in oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb) are observed. There are several components other than hemoglobin in biomedical tissue such as cytochrome oxidase (cyt-ox) and water, and it is important to measure them. We investigated the possibilities of multi-wavelength measurement of the changes in oxy- and deoxy-Hb, the redox state of cyt-ox, and water based on a modified Beer-Lambert law. According to error propagation theory, we searched for the wavelength combination where the estimation errors were minimal in the wavelength range from 650 to 900 nm under several conditions of measured components and number of wavelengths. Next, using the experimental data, we performed the same search. The signal-to-noise ratio (SNR) loss depended on measured components and wavelengths used in the measurement. We calculated the necessary improvement in precision of absorbance measurement when we estimated the changes in the redox state of cyt-ox and water, for maintaining the same level of SNRs in the hemoglobin-only measurement. The measurements of both the redox state of cyt-ox and water were not practical because the SNR losses of Hb became more than 30 dB, while the measurement where only one of them was performed was more feasible. We calculated the required ratio of absorbance change to its noise for the acquisition of cyt-ox at the same SNR of oxy-hemoglobin in hemoglobin-only measurements when the absorbance change caused by cyt-ox was assumed to be one tenth of that of oxy-hemoglobin.

  13. Multispectral imaging using a single bucket detector

    PubMed Central

    Bian, Liheng; Suo, Jinli; Situ, Guohai; Li, Ziwei; Fan, Jingtao; Chen, Feng; Dai, Qionghai

    2016-01-01

    Existing multispectral imagers mostly use available array sensors to separately measure 2D data slices in a 3D spatial-spectral data cube. Thus they suffer from low photon efficiency, limited spectrum range and high cost. To address these issues, we propose to conduct multispectral imaging using a single bucket detector, to take full advantage of its high sensitivity, wide spectrum range, low cost, small size and light weight. Technically, utilizing the detector’s fast response, a scene’s 3D spatial-spectral information is multiplexed into a dense 1D measurement sequence and then demultiplexed computationally under the single pixel imaging scheme. A proof-of-concept setup is built to capture multispectral data of 64 pixels × 64 pixels × 10 wavelength bands ranging from 450 nm to 650 nm, with the acquisition time being 1 minute. The imaging scheme holds great potentials for various low light and airborne applications, and can be easily manufactured as production-volume portable multispectral imagers. PMID:27103168

  14. Multi-wavelength observations of the peculiar red giant HR 3126

    NASA Technical Reports Server (NTRS)

    Pesce, Joseph E.; Stencel, Robert E.; Walter, Frederick M.; Doggett, Jesse; Dachs, Joachim; Whitelock, Patricia A.; Mundt, Reinhard

    1988-01-01

    Ultraviolet observations of the red giant HR 3126 are combined with multi-wavelength data in order to provide a firmer basis for explaining the arc-minute sized nebula surrounding the object. Possibilities as to the location of HR 3126 on the Hertzsprung-Russel diagram, and to the formation mechanisms of the reflection nebula IC 2220 associated with it, are summarized.

  15. Pulse-Shape Control in an All Fiber Multi-Wavelength Doppler Lidar

    NASA Astrophysics Data System (ADS)

    Töws, Albert; Lehmann, Jan; Kurtz, Alfred

    2016-06-01

    Pulse distortion during amplification in fiber amplifiers due to gain saturation and cross talk in a multi-wavelength Doppler lidar are discussed. We present a feedback control technique which is capable of adjusting any predefined pulse shape and show some examples of feedback controlled pulse shapes.

  16. Multi-Wavelength Mode-Locked Laser Arrays for WDM Applications

    NASA Technical Reports Server (NTRS)

    Davis, L.; Young, M.; Dougherty, D.; Keo, S.; Muller, R.; Maker, P.

    1998-01-01

    Multi-wavelength arrays of colliding pulse mode-locked (CPM) lasers have been demonstrated for wavelength division multiplexing (WDM) applications. The need for increased bandwidth is driving the development of both increased speed in time division multiplexing (TDM) and more channels in WDM for fiber optic communication systems.

  17. Multi-wavelength properties of submillimeter-selected galaxies

    NASA Astrophysics Data System (ADS)

    Hainline, Laura Jeannine

    , infrared luminosity, and spectral energy distribution, and use our new constraints to test a variety of assumptions which have been used in the past to predict and infer characteristics of submillimeter-selected galaxies. We also use our new data to compare different populations of high-redshift galaxies selected at different wavelengths in an effort to understand the relationships between the different types of galaxies. First, we use observations of CO rotational line emission with the Green Bank Telescope to constrain the cold gas mass and gas conditions in several submillimeter-selected galaxies. We obtain the first detection of CO(1->0) emission from a submillimeter-selected galaxy, finding that the CO(4->3)/CO(1->0) brightness temperature ratio of ~ 0.26 suggests n(H2) > 3 - 10 × 10 2 cm-3 and the presence of sub-thermally excited gas. The integrated line flux implies a cold molecular gas mass 4 times larger than the mass predicted from the CO(4->3) line, assuming a brightness temperature ratio of 1.0, suggesting that extrapolating molecular gas masses from J [subscript]upper ≥ 3 transitions of CO, which is the primary method of estimating molecular gas masses of high-z galaxies in the literature, leads to considerable uncertainties.Next, we use deep imaging with the Multiband Imaging Photometer for Spitzer (MIPS) on the Spitzer Space Telescope of the spectroscopic sample of radio-detected submillimeter-selected galaxies of Chapman et al. (2005) to derive new estimates of the infrared luminosity for these objects. Our Spitzer data constrain the Wien side of the infrared spectral energy distribution peak of high-redshift submillimeter-selected galaxies, and thus are extremely important to determine the contribution of hot dust emission to the total infrared luminosity. We find that most submillimeter-selected galaxies do not have dominant contributions from hot dust at rest-frame mid-infrared wavelengths. We also find that the spectral energy distribution of the

  18. Computational imaging with a balanced detector.

    PubMed

    Soldevila, F; Clemente, P; Tajahuerce, E; Uribe-Patarroyo, N; Andrés, P; Lancis, J

    2016-01-01

    Single-pixel cameras allow to obtain images in a wide range of challenging scenarios, including broad regions of the electromagnetic spectrum and through scattering media. However, there still exist several drawbacks that single-pixel architectures must address, such as acquisition speed and imaging in the presence of ambient light. In this work we introduce balanced detection in combination with simultaneous complementary illumination in a single-pixel camera. This approach enables to acquire information even when the power of the parasite signal is higher than the signal itself. Furthermore, this novel detection scheme increases both the frame rate and the signal-to-noise ratio of the system. By means of a fast digital micromirror device together with a low numerical aperture collecting system, we are able to produce a live-feed video with a resolution of 64 × 64 pixels at 5 Hz. With advanced undersampling techniques, such as compressive sensing, we can acquire information at rates of 25 Hz. By using this strategy, we foresee real-time biological imaging with large area detectors in conditions where array sensors are unable to operate properly, such as infrared imaging and dealing with objects embedded in turbid media. PMID:27353733

  19. Computational imaging with a balanced detector

    PubMed Central

    Soldevila, F.; Clemente, P.; Tajahuerce, E.; Uribe-Patarroyo, N.; Andrés, P.; Lancis, J.

    2016-01-01

    Single-pixel cameras allow to obtain images in a wide range of challenging scenarios, including broad regions of the electromagnetic spectrum and through scattering media. However, there still exist several drawbacks that single-pixel architectures must address, such as acquisition speed and imaging in the presence of ambient light. In this work we introduce balanced detection in combination with simultaneous complementary illumination in a single-pixel camera. This approach enables to acquire information even when the power of the parasite signal is higher than the signal itself. Furthermore, this novel detection scheme increases both the frame rate and the signal-to-noise ratio of the system. By means of a fast digital micromirror device together with a low numerical aperture collecting system, we are able to produce a live-feed video with a resolution of 64 × 64 pixels at 5 Hz. With advanced undersampling techniques, such as compressive sensing, we can acquire information at rates of 25 Hz. By using this strategy, we foresee real-time biological imaging with large area detectors in conditions where array sensors are unable to operate properly, such as infrared imaging and dealing with objects embedded in turbid media. PMID:27353733

  20. Computational imaging with a balanced detector

    NASA Astrophysics Data System (ADS)

    Soldevila, F.; Clemente, P.; Tajahuerce, E.; Uribe-Patarroyo, N.; Andrés, P.; Lancis, J.

    2016-06-01

    Single-pixel cameras allow to obtain images in a wide range of challenging scenarios, including broad regions of the electromagnetic spectrum and through scattering media. However, there still exist several drawbacks that single-pixel architectures must address, such as acquisition speed and imaging in the presence of ambient light. In this work we introduce balanced detection in combination with simultaneous complementary illumination in a single-pixel camera. This approach enables to acquire information even when the power of the parasite signal is higher than the signal itself. Furthermore, this novel detection scheme increases both the frame rate and the signal-to-noise ratio of the system. By means of a fast digital micromirror device together with a low numerical aperture collecting system, we are able to produce a live-feed video with a resolution of 64 × 64 pixels at 5 Hz. With advanced undersampling techniques, such as compressive sensing, we can acquire information at rates of 25 Hz. By using this strategy, we foresee real-time biological imaging with large area detectors in conditions where array sensors are unable to operate properly, such as infrared imaging and dealing with objects embedded in turbid media.

  1. Dynamics of Coronal Bright Points as Seen by Sun Watcher Using Active Pixel System Detector and Image Processing (SWAP), Atmospheric Imaging Assembly (AIA), and Helioseismic and Magnetic Imager (HMI)

    NASA Astrophysics Data System (ADS)

    Chandrashekhar, K.; Krishna Prasad, S.; Banerjee, D.; Ravindra, B.; Seaton, Daniel B.

    2013-08-01

    The Sun Watcher using Active Pixel system detector and Image Processing (SWAP) onboard the PRoject for OnBoard Autonomy-2 (PROBA2) spacecraft provides images of the solar corona in EUV channel centered at 174 Å. These data, together with the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamics Observatory (SDO), are used to study the dynamics of coronal bright points. The evolution of the magnetic polarities and associated changes in morphology are studied using magnetograms and multi-wavelength imaging. The morphology of the bright points seen in low-resolution SWAP images and high-resolution AIA images show different structures, whereas the intensity variations with time show similar trends in both SWAP 174 Å and AIA 171 Å channels. We observe that bright points are seen in EUV channels corresponding to a magnetic flux of the order of 1018 Mx. We find that there exists a good correlation between total emission from the bright point in several UV-EUV channels and total unsigned photospheric magnetic flux above certain thresholds. The bright points also show periodic brightenings, and we have attempted to find the oscillation periods in bright points and their connection to magnetic-flux changes. The observed periods are generally long (10 - 25 minutes) and there is an indication that the intensity oscillations may be generated by repeated magnetic reconnection.

  2. The endcap Cherenkov ring imaging detector at SLD

    SciTech Connect

    Abe, K.; Hasegawa, K.; Hawegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H.; Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dolinsky, S.

    1995-05-01

    The authors present the Cherenkov Ring Imaging Detector in the endcap regions of the SLD detector and report initial performance. The endcap CRID was completed and commissioned in 1993 and is fully operational for the 1994 run. First Cherenkov rings have been observed. The endcap CRID detectors and fluid systems are described and initial operational experience is discussed.

  3. The Hadron Blind Ring Imaging Cherenkov Detector

    NASA Astrophysics Data System (ADS)

    Blatnik, Marie; Zajac, Stephanie; Hemmick, Tom

    2013-10-01

    Heavy Ion Collisions in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven Lab have hinted at the existence of a new form of matter at high gluon density, the Color Glass Condensate. High energy electron scattering off of nuclei, focusing on the low-x components of the nuclear wave function, will definitively measure this state of matter. However, when a nucleus contributes a low x parton, the reaction products are highly focused in the electron-going direction and have large momentum in the lab system. High-momentum particle identification is particularly challenging. A particle is identifiable by its mass, but tracking algorithms only yield a particle's momentum based on its track's curvature. The particle's velocity is needed to identify the particle. A ring-imaging Cerenkov detector is being developed for the forward angle particle identification from the technological advancements of PHENIX's Hadron-Blind Detector (HBD), which uses Gas Electron Multipliers (GEMs) and pixelated pad planes to detect Cerenkov photons. The new HBD will focus the Cerenkov photons into a ring to determine the parent particle's velocity. Results from the pad plane simulations, construction tests, and test beam run will be presented.

  4. Software development for a Ring Imaging Detector

    NASA Astrophysics Data System (ADS)

    Torisky, Benjamin; Benmokhtar, Fatiha

    2015-04-01

    Jefferson Lab (Jlab) is performing a large-scale upgrade to their Continuous Electron Beam Accelerator Facility (CEBAF) up to 12 GeV beam. The Large Acceptance Spectrometer (CLAS12) in Hall B is being upgraded and a new Ring Imaging CHerenkov (RICH) detector is being developed to provide better kaon - pion separation throughout the 3 to 12 GeV range. With this addition, when the electron beam hits the target, the resulting pions, kaons, and other particles will pass through a wall of translucent aerogel tiles and create Cherenkov radiation. This light can then be accurately detected by a large array of Multi-Anode PhotoMultiplier Tubes (MA-PMT). I am presenting my work on the implementation of Java based reconstruction programs for the RICH in the CLAS12 main analysis package.

  5. Software Development for Ring Imaging Detector

    NASA Astrophysics Data System (ADS)

    Torisky, Benjamin

    2016-03-01

    Jefferson Lab (Jlab) is performing a large-scale upgrade to their Continuous Electron Beam Accelerator Facility (CEBAF) up to 12GeV beam. The Large Acceptance Spectrometer (CLAS12) in Hall B is being upgraded and a new Ring Imaging Cherenkov (RICH) detector is being developed to provide better kaon - pion separation throughout the 3 to 12 GeV range. With this addition, when the electron beam hits the target, the resulting pions, kaons, and other particles will pass through a wall of translucent aerogel tiles and create Cherenkov radiation. This light can then be accurately detected by a large array of Multi-Anode PhotoMultiplier Tubes (MA-PMT). I am presenting an update on my work on the implementation of Java based reconstruction programs for the RICH in the CLAS12 main analysis package.

  6. Multi-wavelength studies of Saturn's rings to constrain ring particle properties and ring structure

    NASA Astrophysics Data System (ADS)

    Spilker, L.; Deau, E.; Morishima, R.; Filacchione, G.; Hedman, M.; Nicholson, P.; Colwell, J.; Bradley, T.

    2012-04-01

    A great deal can be learned about the nature of Saturn's ring particles and their regoliths by modeling the changes in brightness, color and temperature with changing viewing geometry over a wide range of wavelengths, from ultraviolet through the thermal infrared. Data from Cassini's Composite Infrared Spectrometer (CIRS), Visual and Infrared Mapping Spectrometer (VIMS), Imaging Science Subsystem (ISS) and Ultraviolet Imaging Spectrograph (UVIS) are jointly being studied using scans of the lit and unlit main rings (A, B, C and Cassini Division) at multiple geometries and solar elevations. Using multi-wavelength data sets allow us to test different thermal models by combining the effects of particle albedo, regolith grain size and surface roughness with thermal emissivity and inertia, particle spin rate and spin axis orientation. With the high spatial resolution of the Cassini data it is now possible to analyze these effects at smaller spatial scales and characterize regions such as the C ring plateaus and ringlets, where albedo differences may be present. In the CIRS data, over a range of solar elevations from -23 degrees to -8 degrees, the bulk of the temperature variations are confined primarily to phase angle. Only small temperature differences are observed with changing spacecraft elevation. Similar behavior is seen in the ISS color data. Color and temperature dependence with changing solar elevation angle are also observed. VIMS observations show that the IR ice absorption band depths are (almost) independent of phase angle, out to ~140 deg phase, suggesting that interparticle light scattering is relatively unimportant except at very high phase angles. These results imply that the individual properties of the ring particles may play a larger role than the collective properties of the rings, in particular at visible wavelengths. The temperature and color variation with phase angle may be a result of scattering within the regolith and on possibly rough surfaces

  7. GALAXY EVOLUTION IN A COMPLEX ENVIRONMENT: A MULTI-WAVELENGTH STUDY OF HCG 7

    SciTech Connect

    Konstantopoulos, I. S.; Charlton, J. C.; Gronwall, C.; Gallagher, S. C.; Fedotov, K.; Szathmary, D.; Durrell, P. R.; Heiderman, A.; Elmegreen, D. M.; Hibbard, J. E.; Johnson, K. E.; Tzanavaris, P.; Hornschemeier, A. E.; Chandar, R.; Maybhate, A.; Whitmore, B.; Zabludoff, A. E.; English, J.; Mendes de Oliveira, C.; Mulchaey, J. S.

    2010-11-01

    The environment where galaxies are found heavily influences their evolution. Close groupings, like the ones in the cores of galaxy clusters or compact groups, evolve in ways far more dramatic than their isolated counterparts. We have conducted a multi-wavelength study of Hickson Compact Group 7 (HCG 7), consisting of four giant galaxies: three spirals and one lenticular. We use Hubble Space Telescope (HST) imaging to identify and characterize the young and old star cluster populations. We find young massive clusters (YMCs) mostly in the three spirals, while the lenticular features a large, unimodal population of globular clusters (GCs) but no detectable clusters with ages less than a few Gyr. The spatial and approximate age distributions of the {approx}300 YMCs and {approx}150 GCs thus hint at a regular star formation history in the group over a Hubble time. While at first glance the HST data show the galaxies as undisturbed, our deep ground-based, wide-field imaging that extends the HST coverage reveals faint signatures of stellar material in the intragroup medium (IGM). We do not, however, detect the IGM in H I or Chandra X-ray observations, signatures that would be expected to arise from major mergers. Despite this fact, we find that the H I gas content of the individual galaxies and the group as a whole are a third of the expected abundance. The appearance of quiescence is challenged by spectroscopy that reveals an intense ionization continuum in one galaxy nucleus, and post-burst characteristics in another. Our spectroscopic survey of dwarf galaxy members yields a single dwarf elliptical galaxy in an apparent stellar tidal feature. Based on all this information, we suggest an evolutionary scenario for HCG 7, whereby the galaxies convert most of their available gas into stars without the influence of major mergers and ultimately result in a dry merger. As the conditions governing compact groups are reminiscent of galaxies at intermediate redshift, we propose

  8. High time-resolution imaging with the MAMA detector systems

    NASA Technical Reports Server (NTRS)

    Morgan, Jeffrey S.; Timothy, J. Gethyn; Smith, Andrew M.; Hill, Bob; Kasle, David B.

    1990-01-01

    Current uses of the MAMA detector which utilize the photon time-tagging capabilities of these detectors are reported. These applications currently include image stabilization by means of post-processing corrections of platform drift and speckle interferometry. The initial results of a sounding rocket experiment to obtain UV images of NGC 6240 and results from speckle interferometry of Neptune's moon Triton are presented.

  9. Multi-wavelength Raman spectroscopy study of supported vanadia catalysts: Structure identification and quantification

    SciTech Connect

    Wu, Zili

    2014-10-20

    Revealing the structure of supported metal oxide catalysts is a prerequisite for establishing the structure - catalysis relationship. Among a variety of characterization techniques, multi-wavelength Raman spectroscopy, combining resonance Raman and non-resonance Raman with different excitation wavelengths, has recently emerged as a particularly powerful tool in not only identifying but also quantifying the structure of supported metal oxide clusters. In our review, we make use of two supported vanadia systems, VOx/SiO2 and VOx/CeO2, as examples to showcase how one can employ this technique to investigate the heterogeneous structure of active oxide clusters and to understand the complex interaction between the oxide clusters and the support. Moreover, the qualitative and quantitative structural information gained from the multi-wavelength Raman spectroscopy can be utilized to provide fundamental insights for designing more efficient supported metal oxide catalysts.

  10. Multi-wavelength Raman spectroscopy study of supported vanadia catalysts: Structure identification and quantification

    DOE PAGESBeta

    Wu, Zili

    2014-10-20

    Revealing the structure of supported metal oxide catalysts is a prerequisite for establishing the structure - catalysis relationship. Among a variety of characterization techniques, multi-wavelength Raman spectroscopy, combining resonance Raman and non-resonance Raman with different excitation wavelengths, has recently emerged as a particularly powerful tool in not only identifying but also quantifying the structure of supported metal oxide clusters. In our review, we make use of two supported vanadia systems, VOx/SiO2 and VOx/CeO2, as examples to showcase how one can employ this technique to investigate the heterogeneous structure of active oxide clusters and to understand the complex interaction between themore » oxide clusters and the support. Moreover, the qualitative and quantitative structural information gained from the multi-wavelength Raman spectroscopy can be utilized to provide fundamental insights for designing more efficient supported metal oxide catalysts.« less

  11. Frequency domain phase retrieval of simultaneous multi-wavelength phase-shifting interferometry

    NASA Astrophysics Data System (ADS)

    Yin, Zhenxing; Zhong, Liyun; Xu, Xiaofei; Zhang, Wangping; Tian, Jindong; Lu, Xiaoxu

    2016-05-01

    In simultaneous multi-wavelength phase-shifting interferometry, we propose a novel frequency domain phase retrieval (FDPR) algorithm. First, using only a one-time phase-shifting operation, a sequence of simultaneous multi-wavelength phase-shifting interferograms (SPSMWIs) are captured by a monochrome charge-coupled device. Second, by performing a Fourier transform for each pixel of SPSMWIs, the wrapped phases of each wavelength can be retrieved from the complex amplitude located in the spectral peak of each wavelength. Finally, the phase of the synthetic wavelength can be obtained by the subtraction between the wrapped phases of a single wavelength. In this study, the principle and the application condition of the proposed approach are discussed. Both the simulation and the experimental result demonstrate the simple and convenient performance of the proposed FDPR approach.

  12. A New Multi-Wavelength Synoptic Network for Solar Physics and Space Weather

    NASA Astrophysics Data System (ADS)

    Hill, Frank; Roth, Markus; Thompson, Michael

    2013-04-01

    Continuous solar observations are important for many research topics in solar physics, such as magnetic field evolution, flare and CME characteristics, and p-mode oscillation measurements. In addition, space weather operations require constant streams of solar data as input. The deployment of a number of identical instruments around the world in a network has proven to be a very effective strategy for obtaining nearly continuous solar observations. The financial costs of a network are 1-2 orders of magnitude lower than space-based platforms; network instrumentation can be easily accessed for maintenance and upgrades; and telemetry bandwidth is readily available. Currently, there are two solar observing networks with consistent instruments: BiSON and GONG, both designed primarily for helioseismology. In addition, GONG has been augmented with continual magnetic field measurements and H-alpha imagery, with both being used for space weather operational purposes. However, GONG is now 18 years old and getting increasingly more challenging to maintain. There are also at least three scientific motivations for a multi-wavelength network: Recent advances in helioseismology have demonstrated the need for multi-wavelength observations to allow more accurate interpretation of the structure and dynamics below sunspots. Vector magnetometry would greatly benefit from multi-wavelength observations to provide height information and resolve the azimuthal ambiguity. Finally, space weather operations always need a consistent reliable source of continual solar data. This presentation will outline the scientific need for a multi-wavelength network, and discuss some concepts for the design of the instrumentation. A workshop on the topic will be held in Boulder this April.

  13. Novel multi wavelength sensor concept to detect total hemoglobin concentration, methemoglobin and oxygen saturation

    NASA Astrophysics Data System (ADS)

    Timm, Ulrich; Gewiss, Helge; Kraitl, Jens; Stuepmann, Kirstin; Hinz, Michael; Koball, Sebastian; Ewald, Hartmut

    2015-03-01

    The paper will describe the novel multi-wavelength photometric device OxyTrue Hb® which is capable to measure the hemoglobin (Hb) and methemoglobin (MetHb) concentration non-invasively. Clinic trails in blood donation centers and during the dialysis are done to prove and demonstrate the performance of the system. The results are compared to the gold standard, the BGA measurement.

  14. Multi-Wavelength Observations of 3C 273 in 1993-1995

    NASA Technical Reports Server (NTRS)

    vonMontigny, C.; Aller, H.; Aller, M.; Bruhweiler, F.; Collmar, W.; Courvoisier, T. J.-L.; Edwards, P. G.; Fichtel, C. E.; Fruscione, A.; Ghisellini, G.

    1997-01-01

    We present the results of the multi-wavelength campaigns on 3C 273 in 1993-1995. During the observations in late 1993 this quasar showed an increase of its flux for energies >= 100 MeV from about 2.1 x 10(exp -7) photons/sq cm.s to approximately 5.6 x 10(exp -7) photons/sq cm.s during a radio outburst at 14.5, 22 and 37 GHz. However, no one-to-one correlation of the gamma-ray radiation with any frequency could be found. The photon spectral index of the high energy spectrum changed from GAMMA(sub gamma) = (3.20 +/- 0.54) to GAMMA(sub gamma) = (2.20 +/- 0.22) in the sense that the spectrum flattened when the gamma-ray flux increased. Fits of the three most prominent models (synchrotron self-Comptonization, external inverse Comptonization and the proton initiated cascade model) for the explanation of the high gamma-ray emission of active galactic nuclei were performed to the multi-wavelength spectrum of 3C 273 . All three models are able to represent the basic features of the multi-wavelength spectrum. Although there are some differences the data are still not decisive enough to discriminate between the models.

  15. HELP: The Herschel Extragalactic Legacy Project and The Coming of Age of Multi-wavelength Astrophysics

    NASA Astrophysics Data System (ADS)

    Vaccari, M.

    How did galaxies form and evolve? This is one of the most challenging questions in astronomy today. Answering it requires a careful combination of observational and theoretical work to reliably determine the observed properties of cosmic bodies over large portions of the distant Universe on the one hand, and accurately model the physical processes driving their evolution on the other. Most importantly, it requires bringing together disparate multi-wavelength and multi-resolution spectro-photometric datasets in an homogeneous and well-characterized manner so that they are suitable for a rigorous statistical analysis. The Herschel Extragalactic Legacy Project (HELP) funded by the EC FP7 SPACE program aims to achieve this goal by combining the expertise of optical, infrared and radio astronomers to provide a multi-wavelength database for the distant Universe as an accessible value-added resource for the astronomical community. It will do so by bringing together multi-wavelength datasets covering the 1,000 deg2 mapped by Herschel extragalactic surveys in an homogeneous and well-characterized manner, creating a joint lasting legacy from several ambitious sky surveys.

  16. Multi-wavelength seds of Herschel-selected galaxies in the cosmos field

    SciTech Connect

    Lee, Nicholas; Sanders, D. B.; Casey, Caitlin M.; Hung, Chao-Ling; Scoville, N. Z.; Capak, Peter; Bock, J.; Le Floc'h, Emeric; Aussel, Hervé; Ilbert, Olivier; Kartaltepe, Jeyhan S.; Roseboom, Isaac; Oliver, S. J.; Salvato, Mara; Aravena, M.; Berta, S.; Riguccini, L.; Symeonidis, M.

    2013-12-01

    We combine Herschel Photodetector Array Camera and Spectrometer and Spectral and Photometric Imaging Receiver maps of the full 2 deg{sup 2} Cosmic Evolution Survey (COSMOS) field with existing multi-wavelength data to obtain template and model-independent optical-to-far-infrared spectral energy distributions (SEDs) for 4218 Herschel-selected sources with log(L {sub IR}/L {sub ☉}) = 9.4-13.6 and z = 0.02-3.54. Median SEDs are created by binning the optical to far-infrared (FIR) bands available in COSMOS as a function of infrared luminosity. Herschel probes rest-frame wavelengths where the bulk of the infrared radiation is emitted, allowing us to more accurately determine fundamental dust properties of our sample of infrared luminous galaxies. We find that the SED peak wavelength (λ{sub peak}) decreases and the dust mass (M {sub dust}) increases with increasing total infrared luminosity (L {sub IR}). In the lowest infrared luminosity galaxies (log(L {sub IR}/L {sub ☉}) = 10.0-11.5), we see evidence of polycyclic aromatic hydrocarbon (PAH) features (λ ∼ 7-9 μm), while in the highest infrared luminosity galaxies (L {sub IR} > 10{sup 12} L {sub ☉}) we see an increasing contribution of hot dust and/or power-law emission, consistent with the presence of heating from an active galactic nucleus (AGN). We study the relationship between stellar mass and star formation rate of our sample of infrared luminous galaxies and find no evidence that Herschel-selected galaxies follow the SFR/M {sub *} 'main sequence' as previously determined from studies of optically selected, star-forming galaxies. Finally, we compare the mid-infrared to FIR properties of our infrared luminous galaxies using the previously defined diagnostic, IR8 ≡ L {sub IR}/L {sub 8}, and find that galaxies with L {sub IR} ≳ 10{sup 11.3} L {sub ☉} tend to systematically lie above (× 3-5) the IR8 'infrared main sequence', suggesting either suppressed PAH emission or an increasing contribution from

  17. Multi-wavelength population studies of Active Galactic Nuclei and Galaxies using PRIMUS and AEGIS

    NASA Astrophysics Data System (ADS)

    Mendez, Alexander John

    This dissertation uses large galaxy redshift surveys and multi-wavelength imaging to place observational constraints on the evolution of galaxies and the supermassive black holes that they host since the Universe was roughly half its current age. In the first chapter, we use data from the AEGIS survey to present quantitative morphological measurements of green valley galaxies, to constrain the mechanism(s) responsible for quenching star formation in this transition population and creating elliptical galaxies. We show that green galaxies are generally massive (M*~1010.5M sun) disk galaxies with high concentrations of light. We find that major mergers are not the dominant mechanism responsible for quenching star formation, and we find that either more mild external processes or internal secular processes play a crucial role in halting star formation. In the second chapter, we use data from the PRIMUS survey to investigate Spitzer/IRAC and X-ray AGN selection techniques in order to quantify the overlap, uniqueness, contamination, and completeness of each AGN selection. For roughly similar depth IR and X-ray data, we find that ~75% of IR-selected AGN are also identified as X-ray AGN. For the deepest X-ray data, this fraction increases to ~90%, indicating that at most ~10% of IR-selected AGN may be heavily obscured. While similar overall, the IR-AGN samples preferentially contain more luminous AGN, while the X-ray AGN samples identify AGN with a wider range of accretion rates, where the host galaxy light dominates at IR wavelengths. A more complete AGN sample is created by combining both IR and X-ray selected AGN. Finally, we present a clustering study of X-ray AGN, radio AGN and IR AGN selected AGN using spectroscopic redshifts from the PRIMUS and DEEP2 redshift surveys. Using the cross-correlation of AGN with dense galaxy samples, we find differences in the clustering of AGN selected at different wavelengths. However, we find no significant differences in the

  18. Mosaic-Detector-Based Fluorescence Spectral Imager

    NASA Technical Reports Server (NTRS)

    Son, Kyung-Ah; Moon, Jeong

    2007-01-01

    A battery-powered, pen-sized, portable instrument for measuring molecular fluorescence spectra of chemical and biological samples in the field has been proposed. Molecular fluorescence spectroscopy is among the techniques used most frequently in laboratories to analyze compositions of chemical and biological samples. Heretofore, it has been possible to measure fluorescence spectra of molecular species at relative concentrations as low as parts per billion (ppb), with a few nm spectral resolution. The proposed instrument would include a planar array (mosaic) of detectors, onto which a fluorescence spectrum would be spatially mapped. Unlike in the larger laboratory-type molecular fluorescence spectrometers, mapping of wavelengths to spatial positions would be accomplished without use of relatively bulky optical parts. The proposed instrument is expected to be sensitive enough to enable measurement of spectra of chemical species at relative concentrations <1 ppb, with spectral resolution that could be tailored by design to be comparable to a laboratory molecular fluorescence spectrometer. The proposed instrument (see figure) would include a button-cell battery and a laser diode, which would generate the monochromatic ultraviolet light needed to excite fluorescence in a sample. The sample would be held in a cell bounded by far-ultraviolet-transparent quartz or optical glass. The detector array would be, more specifically, a complementary metal oxide/ semiconductor or charge-coupled- device imaging photodetector array, the photodetectors of which would be tailored to respond to light in the wavelength range of the fluorescence spectrum to be measured. The light-input face of the photodetector array would be covered with a matching checkerboard array of multilayer thin film interference filters, such that each pixel in the array would be sensitive only to light in a spectral band narrow enough so as not to overlap significantly with the band of an adjacent pixel. The

  19. X-ray imaging detectors for synchrotron and XFEL sources

    PubMed Central

    Hatsui, Takaki; Graafsma, Heinz

    2015-01-01

    Current trends for X-ray imaging detectors based on hybrid and monolithic detector technologies are reviewed. Hybrid detectors with photon-counting pixels have proven to be very powerful tools at synchrotrons. Recent developments continue to improve their performance, especially for higher spatial resolution at higher count rates with higher frame rates. Recent developments for X-ray free-electron laser (XFEL) experiments provide high-frame-rate integrating detectors with both high sensitivity and high peak signal. Similar performance improvements are sought in monolithic detectors. The monolithic approach also offers a lower noise floor, which is required for the detection of soft X-ray photons. The link between technology development and detector performance is described briefly in the context of potential future capabilities for X-ray imaging detectors. PMID:25995846

  20. Scintillator-fiber charged-particle track-imaging detector

    NASA Technical Reports Server (NTRS)

    Binns, W. R.; Israel, M. H.; Klarmann, J.

    1983-01-01

    A scintillator-fiber charged-particle track-imaging detector has been developed using a bundle of square cross-section plastic scintillator fiber optics, proximity focused onto an image intensified Charge Injection Device (CID) camera. Detector to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei have been exposed and images of their tracks are obtained. This paper presents details of the detector technique, properties of the tracks obtained, and range measurements of 15 MeV protons stopping in the fiber bundle.

  1. Imaging detectors and electronics - A view of the future

    SciTech Connect

    Spieler, Helmuth

    2004-06-16

    Imaging sensors and readout electronics have made tremendous strides in the past two decades. The application of modern semiconductor fabrication techniques and the introduction of customized monolithic integrated circuits have made large scale imaging systems routine in high energy physics. This technology is now finding its way into other areas, such as space missions, synchrotron light sources, and medical imaging. I review current developments and discuss the promise and limits of new technologies. Several detector systems are described as examples of future trends. The discussion emphasizes semiconductor detector systems, but I also include recent developments for large-scale superconducting detector arrays.

  2. Generation of tunable multi-wavelength EDFL by using graphene thin film as nonlinear medium and stabilizer

    NASA Astrophysics Data System (ADS)

    Ahmad, Harith; Hassan, Nor Ahya; Aidit, Siti Nabila; Tiu, Zian Cheak

    2016-07-01

    The applications of graphene thin film as a nonlinear medium and stabilizer to generate a stable multi-wavelength is proposed and demonstrated. A 50 m long highly nonlinear photonic crystal fiber (PCF) is incorporated into the cavity to achieve unstable multi-wavelength based on nonlinear polarization rotation (NPR) effect. By introducing the graphene thin film into the cavity, a stable multi-wavelength oscillation is obtained. The laser generates more than 7 lasings with constant spacing of 0.47 nm. The output is highly stable with power fluctuation of less than 3 dB within a period of 30 min. The multi-wavelength EDFL exhibits a tunability from the center wavelength of 1550 nm to 1560 nm.

  3. Infrared imaging using carbon nanotube-based detector

    NASA Astrophysics Data System (ADS)

    Chen, Hongzhi; Xi, Ning; Song, Bo; Chen, Liangliang; Lai, King W. C.; Lou, Jianyong

    2011-06-01

    Using carbon nanotubes (CNT), high performance infrared detectors have been developed. Since the CNTs have extraordinary optoelectronics properties due to its unique one dimensional geometry and structure, the CNT based infrared detectors have extremely low dark current, low noise equivalent temperature difference (NETD), short response time, and high dynamic range. Most importantly, it can detect 3-5 um middle-wave infrared (MWIR) at room temperature. This unique feature can significantly reduce the size and weight of a MWIR imaging system by eliminating a cryogenic cooling system. However, there are two major difficulties that impede the application of CNT based IR detectors for imaging systems. First, the small diameter of the CNTs results in low fill factor. Secondly, it is difficult to fabricate large scale of detector array for high resolution focal plane due to the limitations on the efficiency and cost of the manufacturing. In this paper, a new CNT based IR imaging system will be presented. Integrating the CNT detectors with photonic crystal resonant cavity, the fill factor of the CNT based IR sensor can reach as high as 0.91. Furthermore, using the compressive sensing technology, a high resolution imaging can be achieved by CNT based IR detectors. The experimental testing results show that the new imaging system can achieve the superb performance enabled by CNT based IR detectors, and, at the same time, overcame its difficulties to achieve high resolution and efficient imaging.

  4. Multianode microchannel array detectors for Space Shuttle imaging applications

    NASA Technical Reports Server (NTRS)

    Timothy, J. G.; Bybee, R. L.

    1981-01-01

    The Multi-Anode Microchannel Arrays (MAMAs) are a family of photoelectric, photoncounting array detectors that have been developed and qualified specifically for use in space. MAMA detectors with formats as large as 256 x 1024 pixels are now in use or under construction for a variety of imaging and tracking applications. These photo-emissive detectors can be operated in a windowless configuration at extreme ultraviolet and soft X-ray wavelengths or in a sealed configuration at ultraviolet and visible wavelengths. The construction and modes-of-operation of the MAMA detectors are briefly described and the scientific objectives of a number of sounding rocket and Space Shuttle instruments utilizing these detectors are outlined. Performance characteristics of the MAMA detectors that are of fundamental importance for operation in the Space Shuttle environment are described and compared with those of the photo-conductive array detectors such as the CCDs and CIDs.

  5. The faint radio source population at 15.7 GHz - II. Multi-wavelength properties

    NASA Astrophysics Data System (ADS)

    Whittam, I. H.; Riley, J. M.; Green, D. A.; Jarvis, M. J.; Vaccari, M.

    2015-11-01

    A complete, flux density limited sample of 96 faint (>0.5 mJy) radio sources is selected from the 10C survey at 15.7 GHz in the Lockman Hole. We have matched this sample to a range of multi-wavelength catalogues, including Spitzer Extragalactic Representative Volume Survey, Spitzer Wide-area Infrared Extragalactic survey, United Kingdom Infrared Telescope Infrared Deep Sky Survey and optical data; multi-wavelength counterparts are found for 80 of the 96 sources and spectroscopic redshifts are available for 24 sources. Photometric redshifts are estimated for the sources with multi-wavelength data available; the median redshift of the sample is 0.91 with an interquartile range of 0.84. Radio-to-optical ratios show that at least 94 per cent of the sample are radio loud, indicating that the 10C sample is dominated by radio galaxies. This is in contrast to samples selected at lower frequencies, where radio-quiet AGN and star-forming galaxies are present in significant numbers at these flux density levels. All six radio-quiet sources have rising radio spectra, suggesting that they are dominated by AGN emission. These results confirm the conclusions of Paper I that the faint, flat-spectrum sources which are found to dominate the 10C sample below ˜1 mJy are the cores of radio galaxies. The properties of the 10C sample are compared to the Square Kilometre Array Design Studies Simulated Skies; a population of low-redshift star-forming galaxies predicted by the simulation is not found in the observed sample.

  6. Anisotropic imaging performance in indirect x-ray imaging detectors

    SciTech Connect

    Badano, Aldo; Kyprianou, Iacovos S.; Sempau, Josep

    2006-08-15

    We report on the variability in imaging system performance due to oblique x-ray incidence, and the associated transport of quanta (both x rays and optical photons) through the phosphor, in columnar indirect digital detectors. The analysis uses MANTIS, a combined x-ray, electron, and optical Monte Carlo transport code freely available. We describe the main features of the simulation method and provide some validation of the phosphor screen models considered in this work. We report x-ray and electron three-dimensional energy deposition distributions and point-response functions (PRFs), including optical spread in columnar phosphor screens of thickness 100 and 500 {mu}m, for 19, 39, 59, and 79 keV monoenergetic x-ray beams incident at 0 deg., 10 deg., and 15 deg. . In addition, we present pulse-height spectra for the same phosphor thickness, x-ray energies, and angles of incidence. Our results suggest that the PRF due to the phosphor blur is highly nonsymmetrical, and that the resolution properties of a columnar screen in a tomographic, or tomosynthetic imaging system varies significantly with the angle of x-ray incidence. Moreover, we find that the noise due to the variability in the number of light photons detected per primary x-ray interaction, summarized in the information or Swank factor, is somewhat independent of thickness and incidence angle of the x-ray beam. Our results also suggest that the anisotropy in the PRF is not less in screens with absorptive backings, while the noise introduced by variations in the gain and optical transport is larger. Predictions from MANTIS, after additional validation, can provide the needed understanding of the extent of such variations, and eventually, lead to the incorporation of the changes in imaging performance with incidence angle into the reconstruction algorithms for volumetric x-ray imaging systems.

  7. Multi-wavelength generation based on cascaded Raman scattering and self-frequency-doubling in KTA

    NASA Astrophysics Data System (ADS)

    Zhong, K.; Li, J. S.; Xu, D. G.; Ding, X.; Zhou, R.; Wen, W. Q.; Li, Z. Y.; Xu, X. Y.; Wang, P.; Yao, J. Q.

    2010-04-01

    A multi-wavelength laser is developed based on cascaded stimulated Raman scattering (SRS) and self-frequency-doubling in an x-cut KTA crystal pumped by an A-O Q-switched Nd:YAG laser. The generation of 1178 nm from cascaded SRS of 234 and 671 cm-1 Raman modes is observed. The six wavelengths, including the fundamental 1064 nm, four Stokes waves at 1091, 1120, 1146, 1178 nm, and the second harmonic generation (SHG) of 1146 nm, are tens to hundreds of millwatts for each at 10 kHz, corresponding to a total conversion efficiency of 8.72%.

  8. Reliability of temperature determination from curve-fitting in multi-wavelength pyrometery

    SciTech Connect

    Ni, P. A.; More, R. M.; Bieniosek, F. M.

    2013-08-04

    Abstract This paper examines the reliability of a widely used method for temperature determination by multi-wavelength pyrometry. In recent WDM experiments with ion-beam heated metal foils, we found that the statistical quality of the fit to the measured data is not necessarily a measure of the accuracy of the inferred temperature. We found a specific example where a second-best fit leads to a more realistic temperature value. The physics issue is the wavelength-dependent emissivity of the hot surface. We discuss improvements of the multi-frequency pyrometry technique, which will give a more reliable determination of the temperature from emission data.

  9. Novel multi wavelength sensor concept to measure carboxy- and methemoglobin concentration non-invasively

    NASA Astrophysics Data System (ADS)

    Timm, Ulrich; Kraitl, Jens; Gewiss, Helge; Kamysek, Svend; Brock, Beate; Ewald, Hartmut

    2016-03-01

    This paper will describe a novel multi-wavelength photometric method to measure carboxyhemoglobin (COHb) and methemoglobin (MetHb) concentration non-invasively. COHb and MetHb are so called dysfunctional hemoglobin derivatives and they are not able to carry oxygen. Standard pulse oximeters are only able to measure two derivatives, namely oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb) but the presence of other derivatives in the blood may distort the readings. The paper presents a new approach of a noninvasive sensor system to measure COHb and MetHb and the validation in vivo and in vitro.

  10. Linear FBG Temperature Sensor Interrogation with Fabry-Perot ITU Multi-wavelength Reference

    PubMed Central

    Park, Hyoung-Jun; Song, Minho

    2008-01-01

    The equidistantly spaced multi-passbands of a Fabry-Perot ITU filter are used as an efficient multi-wavelength reference for fiber Bragg grating sensor demodulation. To compensate for the nonlinear wavelength tuning effect in the FBG sensor demodulator, a polynomial fitting algorithm was applied to the temporal peaks of the wavelength-scanned ITU filter. The fitted wavelength values are assigned to the peak locations of the FBG sensor reflections, obtaining constant accuracy, regardless of the wavelength scan range and frequency. A linearity error of about 0.18% against a reference thermocouple thermometer was obtained with the suggested method.

  11. Binaries across the spectrum - the case for simultaneous multi-wavelength studies

    NASA Astrophysics Data System (ADS)

    Middleton, M.

    2016-06-01

    Accreting binary systems harbouring a compact-object radiate across many orders of magnitude in frequency due to their various physical structures and processes (jet/outflow, inward accretion flow + secondary star). Typical observations of their broad-band SEDs provides valuable insights into the time-averaged energetics, however, *time-resolved* studies are potentially even more powerful as binary systems vary on relatively short timescales and we are provided a means by which to study how the physical structures interact. I will review some of the progress made in studying such systems using time-resolved analyses and discuss the future requirements for simultaneous multi-wavelength observations.

  12. Development of a GSO positron/single-photon imaging detector

    NASA Astrophysics Data System (ADS)

    Yamamoto, S.; Matsumoto, K.; Senda, M.

    2006-01-01

    We have developed and tested a GSO (gadolinium oxyorthosilicate) position-sensitive gamma detector which can be used with positron and single-photon radionuclides for imaging breast cancer or sentinel lymph node detection. Because GSO has a relatively good energy resolution for annihilation gammas as well as low energy gamma photons, and does not contain any natural radioisotopes, it can be used for positron imaging and lower energy single-photon imaging. The imaging detector consists of a GSO block, 2 inch square multi-channel position-sensitive photo-multiplier tube (PSPMT), and associated electronics. The size of a single GSO element was 2.9 mm × 2.9 mm × 20 mm and these elements were arranged into 15 × 15 matrixes to form a block that was optically coupled to the PSPMT. It was possible to separate all GSO crystals into a two-dimensional position histogram for annihilation gammas (511 keV) and low energy gamma photons (122 keV). The typical energy resolution was 24% FWHM and 37% FWHM for 511 keV and 122 keV gamma photons, respectively. For the positron imaging, coincidence between the imaging detector and a single gamma probe is measured. For the single-photon imaging, a tungsten collimator is mounted in front of the imaging detector. With this configuration, it was possible to image both positron radionuclides and low energy single-photon radionuclides. We measured spatial resolution and sensitivity as well as image quality of the developed imaging detector. Results indicated that the developed imaging detector has the potential to be a new and useful instrument for nuclear medicine.

  13. The ring imaging Cherenkov detector for Fermilab experiment 665

    SciTech Connect

    Coutrakon, G.B.; Dhawan, S.; Schuler, P.

    1988-02-01

    The authors describe a ring imaging Cherenkov counter (RICH) which uses a multiwire proportional chamber (MWPC) with cathode pad readout as a UV photon detector. The detector has 10800 pads, each connected to a charge sensitive amplifier, within an area of 55 x 95 cm/sup 2/. The detector offers high data rate capability and a chamber sensitive time of less than 250 nsec. In addition, the detector has 1 mm spatial resolution and a multi-hit capability of about 50 photons/event.

  14. Photoconducting positions monitor and imaging detector

    DOEpatents

    Shu, Deming; Kuzay, Tuncer M.

    2000-01-01

    A photoconductive, high energy photon beam detector/monitor for detecting x-rays and gamma radiation, having a thin, disk-shaped diamond substrate with a first and second surface, and electrically conductive coatings, or electrodes, of a predetermined configuration or pattern, disposed on the surfaces of the substrate. A voltage source and a current amplifier is connected to the electrodes to provide a voltage bias to the electrodes and to amplify signals from the detector.

  15. Imaging characteristics of the Extreme Ultraviolet Explorer microchannel plate detectors

    NASA Technical Reports Server (NTRS)

    Vallerga, J. V.; Kaplan, G. C.; Siegmund, O. H. W.; Lampton, M.; Malina, R. F.

    1989-01-01

    The Extreme Ultraviolet Explorer (EUVE) satellite will conduct an all-sky survey over the wavelength range from 70 A to 760 A using four grazing-incidence telescopes and seven microchannel-plate (MCP) detectors. The imaging photon-counting MCP detectors have active areas of 19.6 cm2. Photon arrival position is determined using a wedge-and-strip anode and associated pulse-encoding electronics. The imaging characteristics of the EUVE flight detectors are presented including image distortion, flat-field response, and spatial differential nonlinearity. Also included is a detailed discussion of image distortions due to the detector mechanical assembly, the wedge-and-strip anode, and the electronics. Model predictions of these distortions are compared to preflight calibration images which show distortions less than 1.3 percent rms of the detector diameter of 50 mm before correction. The plans for correcting these residual detector image distortions to less than 0.1 percent rms are also presented.

  16. Photoacoustic section imaging with an integrating cylindrical detector

    NASA Astrophysics Data System (ADS)

    Gratt, Sibylle; Passler, Klaus; Nuster, Robert; Paltauf, Guenther

    2011-07-01

    A piezoelectric detector with cylindrical shape for photoacoustic section imaging is characterized. This detector is larger than the imaging object in direction of the cylinder axis, giving rise to its integrating properties. Its focal volume has the shape of a slice and the acquisition of signals for one section image requires rotation of an object about an axis perpendicular to this slice. Image reconstruction from the signals requires the application of the inverse Radon transform. It is shown that implementing the Abel transform is a suitable step in data processing, allowing speeding up the data acquisition since the scanning angle can be reduced. The resolution of the detector was estimated in directions perpendicular and parallel to the detection plane. An upper limit for the out of plane resolution is given and section images of a zebra fish are shown.

  17. Demonstration of Aerosol Property Profiling by Multi-wavelength Lidar Under Varying Relative Humidity Conditions

    NASA Technical Reports Server (NTRS)

    Whiteman, D.N.; Veselovskii, I.; Kolgotin, A.; Korenskii, M.; Andrews, E.

    2008-01-01

    The feasibility of using a multi-wavelength Mie-Raman lidar based on a tripled Nd:YAG laser for profiling aerosol physical parameters in the planetary boundary layer (PBL) under varying conditions of relative humidity (RH) is studied. The lidar quantifies three aerosol backscattering and two extinction coefficients and from these optical data the particle parameters such as concentration, size and complex refractive index are retrieved through inversion with regularization. The column-integrated, lidar-derived parameters are compared with results from the AERONET sun photometer. The lidar and sun photometer agree well in the characterization of the fine mode parameters, however the lidar shows less sensitivity to coarse mode. The lidar results reveal a strong dependence of particle properties on RH. The height regions with enhanced RH are characterized by an increase of backscattering and extinction coefficient and a decrease in the Angstrom exponent coinciding with an increase in the particle size. We present data selection techniques useful for selecting cases that can support the calculation of hygroscopic growth parameters using lidar. Hygroscopic growth factors calculated using these techniques agree with expectations despite the lack of co-located radiosonde data. Despite this limitation, the results demonstrate the potential of multi-wavelength Raman lidar technique for study of aerosol humidification process.

  18. Multi-wavelength polarimetry and variability study of M87 jet during 2002-2008

    NASA Astrophysics Data System (ADS)

    Avachat, Sayali S.; Perlman, Eric S.; Cara, Mihai; Owen, Frazer; Harris, Daniel E.; Sparks, William B.; Li, Kunyang; Kosak, Katie

    2016-01-01

    In this dissertation, we present the multi-wavelength study of M87 jet. We compare the radio and optical polarimetry and variability. We attempt to study the spectrum of the jet in radio through X-rays wavelengths. By comparing the data with previously published VLA and HST observations, we show that the jet's morphology in total and polarized light is changing significantly on timescales of ~1 decade. We are looking for the variability of different knots and changes in their spectra using our deep, high resolution observations of the jet between 2002 and 2008. The observations have 2-3 times better resolution that any similar previous study (Perlman et al. 1999) in addition allowing us to observe variability. During this time, the nucleus showed month-scale variability in optical and X-rays and also flared twice in all wave- lengths including radio. The knot HST-1, located closest to the nucleus, displayed a huge flare, increasing about 100 times in brightness. The knot A and B complex shows variations in polarization structures indicating the presence of a helical magnetic field which may be responsible for the in-situ particle accelerations in the jet. We compare the evolution of different knots and components of the jet, when our observations overlap with the multi-wavelength monitoring campaigns conducted with HST and Chandra and comment on particle acceleration and main emission processes. We further use the data to investigate the observed 3-dimensional structure of the jet and the magnetic field structure.

  19. [Measurement of multi-wavelength pulse oxygen saturation based on dynamic spectroscopy].

    PubMed

    Wang, Xiao-Fei; Zhao, Wen-Jun

    2014-05-01

    The present paper puts forward multi-wavelength pulse oxygen saturation measurement based on dynamic spectroscopy to do the non-invasive determination of oxygen saturation. Compared to conventional ways, the new method makes full use of more wavelengths light and improves the measurement accuracy. During the experiment, the in-vivo measurements were carried out on 60 patients and their spectroscopic data were collected by the high sensitivity type fiber optic spectrometer. Singletrial estimation method was used to extract the dynamic spectroscopy at the wavelengths of 606. 44 approximately 987. 55 nm. Oxygen saturation obtained from arterial blood gas analysis is regarded as the true value. Synergy interval partial least square (siPLS) was used to establish the calibration model of subjects' oxygen saturation values against dynamic spectroscopy data. The relative error of prediction is +/-0. 017 6, but the relative error of the subjects in the same set measured by the patient monitor which was two-wavelength measure system is +/-0. 116 4. Measurement results show that the use of the high sensitivity type fiber optic spectrometer to collect multi-wavelength spectroscopic data and dynamic spectroscopy method to process data can do better in improving the accuracy of the oxygen saturation measurement. PMID:25095431

  20. Multi-wavelength polarimetry and variability study of M87 jet during 2003-2008

    NASA Astrophysics Data System (ADS)

    Avachat, Sayali S.; Perlman, Eric S.; Cara, Mihai; Owen, Frazer N.; Harris, Daniel E.; Sparks, William B.; Li, kunyang; Kosak, Katie; Georganopoulos, Markos

    2016-04-01

    We present the multi-wavelength study of M87’s jet . We compare the radio and optical polarimetry and variability and attempt to study the spectrum of the jet in radio through X-rays wavelengths. By comparing the data with previously published VLA and HST observations, we show that the jet's morphology in total and polarized light is changing significantly on timescales of ~1 decade. We are looking for the variability of different knots and changes in their spectra using our deep, high resolution observations of the jet between 2003 and 2008. The observations have 2-3 times better resolution that any similar previous study (Perlman et al. 1999) in addition allowing us to observe variability. During this time, the nucleus showed month-scale variability in optical and X-rays and also flared twice in all wave- lengths including radio. The knot HST-1, located closest to the nucleus, displayed a huge flare, increasing about 100 times in brightness. The knot A and B complex shows variations in polarization structures indicating the presence of a helical magnetic field which may be responsible for the in-situ particle accelerations in the jet. We compare the evolution of different knots and components of the jet, when our observations overlap with the multi-wavelength monitoring campaigns conducted with HST and Chandra and comment on particle acceleration and main emission processes. We further use the data to investigate the observed 3-dimensional structure of the jet and the magnetic field structure.

  1. Magnetic reconnection signatures in the solar atmosphere: results from multi-wavelength observations

    NASA Astrophysics Data System (ADS)

    Zuccarello, F.; Guglielmino, S. L.; Romano, P.

    In the solar atmosphere magnetic reconnection is invoked as the main mechanism causing very energetic events (1028 - 1032 erg), like flares and coronal mass ejections, as well as other less energetic phenomena, like microflares, X-ray jets and chromospheric surges. In the last decade, thanks to high spatial resolution, multi-wavelength observations carried out by both ground-based telescopes (THEMIS, SST, VTT, DST) and space-born satellites (SOHO, TRACE, RHESSI, HINODE), it has been possible to study these phenomena and several signatures of the occurrence of magnetic reconnection have been singled out. In this paper, we describe some results obtained from the analysis of multi-wavelength observations carried out in the last years, with special emphasis on those events that were characterized by plasma outflows from the reconnection site. The events here discussed are relevant to some active regions observed on the Sun, characterized by the interaction of different bundles of magnetic flux tubes, as a consequence of phenomena of emergence of new magnetic flux from the subphotospheric layers and/or of cancellation of magnetic fragments. We report on these phenomena in order to give a contribution to the possibility to find a similarity with jets observed in AGNs.

  2. Stable multi-wavelength fiber laser based on a compounded nonlinear polarization rotation effect

    NASA Astrophysics Data System (ADS)

    Zou, Hui; Lou, Shuqin; Ma, Jianli; Su, Wei; Han, Bolin; Shen, Xiao

    2014-11-01

    A stable multi-wavelength polarization-maintaining erbium-doped fiber (PM-EDF) laser with high signal-to-noise ratio (SNR) based on a compounded nonlinear polarization rotation effect (CNPRE) is proposed and demonstrated. In order to effectively reduce homogeneous broadening of EDF and then to the alleviate mode competition, two sandwich configurations formed by a polarization dependent isolator (PDI) or a segment of single-mode fiber sandwiched between two polarization controllers (PC), are introduced into the ring cavity to generate the CNPRE. A home-made asymmetry twin-core fiber (ATCF) is also incorporated in the ring cavity as a comb filter. With only 150 mW pump power, there are up to 45-wavelengths lasing with the approximate amplitude in a 3 dB bandwidth generated at room temperature. The wavelength spacing between the adjacent peaks is 0.29 nm and the highest SNRs reach 41.5 dB by optimizing the state of polarization of PCs. The power fluctuation and wavelength shift for each lasing wavelength are less than 0.05 dB and 0.02 nm, respectively. This indicates that the proposed multi-wavelength fiber laser can be stably operated at room temperature.

  3. Double spacing multi-wavelength L-band Brillouin erbium fiber laser with Raman pump

    NASA Astrophysics Data System (ADS)

    Ahmad, B. A.; Al-Alimi, A. W.; Abas, A. F.; Mokhtar, M.; Harun, S. W.; Mahdi, M. A.

    2012-11-01

    A new multi-wavelength Brillouin erbium fiber laser (BEFL), which operates in the L-band region with double frequency Brillouin spacing, is demonstrated. This design uses a Raman pump (RP) and a piece of 2 km highly nonlinear fiber as a gain medium. The double frequency spacing is achieved by employing a dual ring configuration, which is formed by utilizing a four-port circulator that removes the odd-order Stoke signals. Twenty Stokes and seventeen anti-Stokes lines, which have optical signal to noise ratio (OSNR) greater than 15 dB, are generated simultaneously with a spacing of 0.16 nm when Brillouin pump and RP powers were fixed at the optimum values of 8 dBm and 40 mW, respectively. The BEFL can be tuned in the range between 1591 nm to 1618 nm. The proposed configuration increases the number of lines generated and the OSNR, and thus allows a compact multi-wavelength laser source to be realized.

  4. MODELING MULTI-WAVELENGTH STELLAR ASTROMETRY. I. SIM LITE OBSERVATIONS OF INTERACTING BINARIES

    SciTech Connect

    Coughlin, Jeffrey L.; Harrison, Thomas E.; Gelino, Dawn M.; Ciardi, David R.; Hoard, D. W.; Wachter, Stefanie; Benedict, G. Fritz; McArthur, Barbara E.; Howell, Steve B.

    2010-07-10

    Interacting binaries (IBs) consist of a secondary star that fills or is very close to filling its Roche lobe, resulting in accretion onto the primary star, which is often, but not always, a compact object. In many cases, the primary star, secondary star, and the accretion disk can all be significant sources of luminosity. SIM Lite will only measure the photocenter of an astrometric target, and thus determining the true astrometric orbits of such systems will be difficult. We have modified the Eclipsing Light Curve code to allow us to model the flux-weighted reflex motions of IBs, in a code we call REFLUX. This code gives us sufficient flexibility to investigate nearly every configuration of IB. We find that SIM Lite will be able to determine astrometric orbits for all sufficiently bright IBs where the primary or secondary star dominates the luminosity. For systems where there are multiple components that comprise the spectrum in the optical bandpass accessible to SIM Lite, we find it is possible to obtain absolute masses for both components, although multi-wavelength photometry will be required to disentangle the multiple components. In all cases, SIM Lite will at least yield accurate inclinations and provide valuable information that will allow us to begin to understand the complex evolution of mass-transferring binaries. It is critical that SIM Lite maintains a multi-wavelength capability to allow for the proper deconvolution of the astrometric orbits in multi-component systems.

  5. Modelling the multi-wavelength emission of flat-spectrum radio quasar 3C 279

    NASA Astrophysics Data System (ADS)

    Zheng, Y. G.; Yang, C. Y.

    2016-04-01

    We employ a length-dependent conical jet model for the jet structure and emission properties of flat-spectrum radio quasar 3C 279 in the steady state. In the model, ultra-relativistic leptons are injected at the base of the jet and propagate along the jet structure. Non-thermal photons are produced by both synchrotron emission and inverse Compton scattering off synchrotron photons and external soft photons at each segment of the jet. We derive the total energy spectra contribution through integrating every segment. We apply the model to the quasi-simultaneous multi-wavelength observed data of two quiescent epochs. Using the observed radio data of the source, we determine the length of the jet L ˜ 100 pc and the magnetic field B0 ˜ 0.1-1 G at the base of the jet. Assuming a steady geometry of the jet structure and suitable physical parameters, we reproduce the multi-wavelength spectra during two quiescent observed epochs. Our results show that the initial γ-ray emission site is ˜0.5 pc from the black hole.

  6. A novel phoswich imaging detector for simultaneous beta and coincidence-gamma imaging of plant leaves

    NASA Astrophysics Data System (ADS)

    Wu, Heyu; Tai, Yuan-Chuan

    2011-09-01

    To meet the growing demand for functional imaging technology for use in studying plant biology, we are developing a novel technique that permits simultaneous imaging of escaped positrons and coincidence gammas from annihilation of positrons within an intake leaf. The multi-modality imaging system will include two planar detectors: one is a typical PET detector array and the other is a phoswich imaging detector that detects both beta and gamma. The novel phoswich detector is made of a plastic scintillator, a lutetium oxyorthosilicate (LSO) array, and a position sensitive photomultiplier tube (PS-PMT). The plastic scintillator serves as a beta detector, while the LSO array serves as a gamma detector and light guide that couples scintillation light from the plastic detector to the PMT. In our prototype, the PMT signal was fed into the Siemens QuickSilver electronics to achieve shaping and waveform sampling. Pulse-shape discrimination based on the detectors' decay times (2.1 ns for plastic and 40 ns for LSO) was used to differentiate beta and gamma events using the common PMT signals. Using our prototype phoswich detector, we simultaneously measured a beta image and gamma events (in single mode). The beta image showed a resolution of 1.6 mm full-width-at-half-maximum using F-18 line sources. Because this shows promise for plant-scale imaging, our future plans include development of a fully functional simultaneous beta-and-coincidence-gamma imager with sub-millimeter resolution imaging capability for both modalities.

  7. CMOS APS detector characterization for quantitative X-ray imaging

    NASA Astrophysics Data System (ADS)

    Endrizzi, Marco; Oliva, Piernicola; Golosio, Bruno; Delogu, Pasquale

    2013-03-01

    An X-ray Imaging detector based on CMOS Active Pixel Sensor and structured scintillator is characterized for quantitative X-ray imaging in the energy range 11-30 keV. Linearity, dark noise, spatial resolution and flat-field correction are the characteristics of the detector subject of investigation. The detector response, in terms of mean Analog-to-Digital Unit and noise, is modeled as a function of the energy and intensity of the X-rays. The model is directly tested using monochromatic X-ray beams and it is also indirectly validated by means of polychromatic X-ray-tube spectra. Such a characterization is suitable for quantitative X-ray imaging and the model can be used in simulation studies that take into account the actual performance of the detector.

  8. Three-dimensional microscopy by laser scanning and multi-wavelength digital holography

    NASA Astrophysics Data System (ADS)

    Khmaladze, Alexander

    This dissertation presents techniques of three-dimensional microscopy. First, an economical method of microscopic image formation that employs a raster-scanning laser beam focused on a sample, while non-imaging detector receives the scattered light is presented. The images produced by this method are analogous to the scanning electron microscopy with visible effects of shadowing and reflection. Compared to a conventional wide-field imaging system, the system allows for a greater flexibility, as the variety of optical detectors, such as PMT and position-sensitive quadrant photodiode can be used to acquire images. The system demonstrates a simple, low-cost method of achieving the resolution on the order of a micron. A further gain in terms of resolution and the depth of focus by using Bessel rather than Gaussian beams is discussed. Then, a phase-imaging technique to quantitatively study the three-dimensional structure of reflective and transmissive microscopic samples is presented. The method, based on the simultaneous dual-wavelength digital holography, allows for higher axial range at which the unambiguous phase imaging can be performed. The technique is capable of nanometer axial resolution. The noise level, which increases as a result of using two wavelengths, is then reduced to the level of a single wavelength. The method compares favorably to software unwrapping, as the technique does not produce nonexistent phase steps. Curvature mismatch between the reference and object beams is numerically compensated. The 3D images of porous coal samples and SKOV-3 ovarian cancer cells are presented.

  9. Flat detector ghost image reduction by UV irradiation

    NASA Astrophysics Data System (ADS)

    Snoeren, Rudolph M.; Steinhauser, Heidrun; Alving, Lex; Stouten, Hans; de With, Peter H. N.

    2009-02-01

    We study flat detectors for X-ray imaging performance degradation. In cone beam C-arm-CT, memory effects have a detrimental effect on image quality. Depending on the magnitude and history of irradiance differences, detector sensitivity variations may persist for a long period of time (days) and are visible as rings upon 3D reconstruction. A new method is proposed for reducing memory effects produced in CsI:Tl based Flat Detector X-ray imaging, which is based upon trap-filling by UV-light. For experiments, a commercial detector has been modified such that UV back-lighting is accomplished. A regular LED refresh light array for reducing photodiode temporal effects is interleaved with UV LED sub-arrays of different wavelengths in the near UV range. The array irradiates the scintillator through translucent parts of the detector substrate. In order to assess the efficacy of the method, ghost images are imprinted by well-defined transitions between direct radiation and attenuated or shuttered radiation. As an advantage, the new method accomplishes ghost-prevention, either by (1) continuous trap-filling at image-synchronous UV light pulsing, or (2) by applying a single dose of UV light. As a result, ring artefacts in reconstructed 3D-images are reduced to low levels. An effective wavelength has been found and an equilibrium UV dosage could be set for effective trap-filling. The overall sensitivity of the detector increases at saturated trap-filling. It was found that with optimised detector settings, i.e. optimum saturated trap-filling, the dependence on X-ray irradiation levels is low, so that the usage of the detector and its performance is robust.

  10. Microelectronics used for Semiconductor Imaging Detectors

    SciTech Connect

    Heijne, Erik H. M.

    2010-01-05

    Semiconductor crystal technology, microelectronics developments and nuclear particle detection have been in a relation of symbiosis, all the way from the beginning. The increase of complexity in electronics chips can now be applied to obtain much more information on the incident nuclear radiation. Some basic technologies are described, in order to acquire insight in possibilities and limitations for the most recent detectors.

  11. Scintillator-fiber charged particle track-imaging detector

    NASA Technical Reports Server (NTRS)

    Binns, W. R.; Israel, M. H.; Klarmann, J.

    1983-01-01

    A scintillator-fiber charged-particle track-imaging detector was developed using a bundle of square cross section plastic scintillator fiber optics, proximity focused onto an image intensified charge injection device (CID) camera. The tracks of charged particle penetrating into the scintillator fiber bundle are projected onto the CID camera and the imaging information is read out in video format. The detector was exposed to beams of 15 MeV protons and relativistic Neon, Manganese, and Gold nuclei and images of their tracks were obtained. Details of the detector technique, properties of the tracks obtained, and preliminary range measurements of 15 MeV protons stopping in the fiber bundle are presented.

  12. Detectors for medical radioisotope imaging: demands and perspectives

    NASA Astrophysics Data System (ADS)

    Lopes, M. I.; Chepel, V.

    2004-10-01

    Radioisotope imaging is used to obtain information on biochemical processes in living organisms, being a tool of increasing importance for medical diagnosis. The improvement and expansion of these techniques depend on the progress attained in several areas, such as radionuclide production, radiopharmaceuticals, radiation detectors and image reconstruction algorithms. This review paper will be concerned only with the detector technology. We will review in general terms the present status of medical radioisotope imaging instrumentation with the emphasis put on the developments of high-resolution gamma cameras and PET detector systems for scinti-mammography and animal imaging. The present trend to combine two or more modalities in a single machine in order to obtain complementary information will also be considered.

  13. Simulation of computed radiography with imaging plate detectors

    SciTech Connect

    Tisseur, D.; Costin, M.; Mathy, F.; Schumm, A.

    2014-02-18

    Computed radiography (CR) using phosphor imaging plate detectors is taking an increasing place in Radiography Testing. CR uses similar equipment as conventional radiography except that the classical X-ray film is replaced by a numerical detector, called image plate (IP), which is made of a photostimulable layer and which is read by a scanning device through photostimulated luminescence. Such digital radiography has already demonstrated important benefits in terms of exposure time, decrease of source energies and thus reduction of radioprotection area besides being a solution without effluents. This paper presents a model for the simulation of radiography with image plate detectors in CIVA together with examples of validation of the model. The study consists in a cross comparison between experimental and simulation results obtained on a step wedge with a classical X-ray tube. Results are proposed in particular with wire Image quality Indicator (IQI) and duplex IQI.

  14. Atmospheric aerosol characterization combining multi-wavelength Raman lidar and MAX-DOAS measurements in Gwanjgu

    NASA Astrophysics Data System (ADS)

    Chong, Jihyo; Shin, Dong Ho; Kim, Kwang Chul; Lee, Kwon-Ho; Shin, Sungkyun; Noh, Young M.; Müller, Detlef; Kim, Young J.

    2011-11-01

    Integrated approach has been adopted at the ADvanced Environmental Research Center (ADEMRC), Gwangju Institute of Science and Technology (GIST), Korea for effective monitoring of atmospheric aerosol. Various active and passive optical remote sensing techniques such as multi-wavelength (3β+2α+1δ) Raman LIDAR, sun-photometry, MAX-DOAS, and satellite retrieval have been utilized. This integrated monitoring system approach combined with in-situ surface measurement is to allow better characterization of physical and optical properties of atmospheric aerosol. Information on the vertical distribution and microphysical properties of atmospheric aerosol is important for understanding its transport characteristics as well as radiative effect. The GIST multi-wavelength (3β + 2α+1δ) Raman lidar system can measure vertical profiles of optical properties of atmospheric aerosols such as extinction coefficients at 355 and 532nm, particle backscatter coefficients at 355, 532 and 1064 nm, and depolarization ratio at 532nm. The incomplete overlap between the telescope field-of-view and beam divergence of the transmitting laser significantly affects lidar measurement, resulting in higher uncertainty near the surface where atmospheric aerosols of interest are concentrated. Differential Optical Absorption Spectroscopy (DOAS) technique is applied as a complementary tool for the detection of atmospheric aerosols near the surface. The passive Multi-Axis DOAS (MAX-DOAS) technique uses scattered sunlight as a light source from several viewing directions. Recently developed aerosol retrieval algorithm based on O4 slant column densities (SCDs) measured at UV and visible wavelengths has been utilized to derive aerosol information (e.g., aerosol optical depth (AOD) and aerosol extinction coefficients (AECs)) in the lower troposphere. The aerosol extinction coefficient at 356 nm was retrieved for the 0-1 and 1-2 km layers based on the MAX-DOAS measurements using the retrieval algorithm

  15. Reconstruction algorithms for optoacoustic imaging based on fiber optic detectors

    NASA Astrophysics Data System (ADS)

    Lamela, Horacio; Díaz-Tendero, Gonzalo; Gutiérrez, Rebeca; Gallego, Daniel

    2011-06-01

    Optoacoustic Imaging (OAI), a novel hybrid imaging technology, offers high contrast, molecular specificity and excellent resolution to overcome limitations of the current clinical modalities for detection of solid tumors. The exact time-domain reconstruction formula produces images with excellent resolution but poor contrast. Some approximate time-domain filtered back-projection reconstruction algorithms have also been reported to solve this problem. A wavelet transform implementation filtering can be used to sharpen object boundaries while simultaneously preserving high contrast of the reconstructed objects. In this paper, several algorithms, based on Back Projection (BP) techniques, have been suggested to process OA images in conjunction with signal filtering for ultrasonic point detectors and integral detectors. We apply these techniques first directly to a numerical generated sample image and then to the laserdigitalized image of a tissue phantom, obtaining in both cases the best results in resolution and contrast for a waveletbased filter.

  16. Monte Carlo studies for medical imaging detector optimization

    NASA Astrophysics Data System (ADS)

    Fois, G. R.; Cisbani, E.; Garibaldi, F.

    2016-02-01

    This work reports on the Monte Carlo optimization studies of detection systems for Molecular Breast Imaging with radionuclides and Bremsstrahlung Imaging in nuclear medicine. Molecular Breast Imaging requires competing performances of the detectors: high efficiency and high spatial resolutions; in this direction, it has been proposed an innovative device which combines images from two different, and somehow complementary, detectors at the opposite sides of the breast. The dual detector design allows for spot compression and improves significantly the performance of the overall system if all components are well tuned, layout and processing carefully optimized; in this direction the Monte Carlo simulation represents a valuable tools. In recent years, Bremsstrahlung Imaging potentiality in internal radiotherapy (with beta-radiopharmaceuticals) has been clearly emerged; Bremsstrahlung Imaging is currently performed with existing detector generally used for single photon radioisotopes. We are evaluating the possibility to adapt an existing compact gamma camera and optimize by Monte Carlo its performance for Bremsstrahlung imaging with photons emitted by the beta- from 90 Y.

  17. A Photon Counting Imaging Detector for NASA Exoplanet Mission

    NASA Astrophysics Data System (ADS)

    Figer, Donald

    The key objective of the proposed project is to advance the maturity of a 256x256 pixel single-photon optical imaging detector. The detector has zero read noise and is resilient against the harsh effects of radiation in space. We expect that the device will have state-of-the-art performance in other parameters, e.g., high quantum efficiency from UV to 1 #m, low dark current, etc.

  18. Cherenkov Ring Imaging Detector front-end electronics

    SciTech Connect

    Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.; Marshall, D.; Muller, D.; Nagamine, T.; Oxoby, G.; Ratcliff, B.; Rensing, P.; Schultz, D.; Shapiro, S.; Simopoulos, C.; Solodov, E.; Suekane, F.; Toge, N.; Va'Vra, J.; Williams, S. ); Wilson, R.J.; Whitaker, J.S. . Dept.

    1990-10-01

    The SLD Cherenkov Ring Imaging Detector use a proportional wire detector for which a single channel hybrid has been developed. It consists of a preamplifier, gain selectable amplifier, load driver amplifier, power switching, and precision calibrator. For this hybrid, a bipolar, semicustom integrated circuit has been designed which includes video operational amplifiers for two of the gain stages. This approach allows maximization of the detector volume, allows DC coupling, and enables gain selection. System tests show good noise performance, calibration precision, system linearity, and signal shape uniformity over the full dynamic range. 10 refs., 8 figs.

  19. Multi-wavelength resonance Raman spectroscopy of bacteria to study the effects of growth condition

    NASA Astrophysics Data System (ADS)

    Kunapareddy, Nagapratima; Grun, Jacob; Lunsford, Robert; Gillis, David; Nikitin, Sergei; Wang, Zheng

    2012-06-01

    We will examine the use of multi-wavelength UV resonance-Raman signatures to identify the effects of growth phase on different types of bacteria. Gram positive and gram-negative species, Escherichia coli, Bacillus cereus, Citrobacter koseri and Citrobacter braakii were grown to logarithmic and stationary phases in different culture media. Raman spectra of bacteria were obtained by sequential illumination of samples between 220 and 260 nm; a range which encompasses the resonance frequencies of cellular components. In addition to the information contained in the single spectrum, this two-dimensional signature contains information reflecting variations in resonance cross sections with illumination wavelength. Results of our algorithms in identifying the differences between these germs are discussed. Preliminary results indicate that growth affects the Raman signature, but not to an extent that would negate identification of the species.

  20. Multi-wavelength metal vapor laser systems for solving applied problems of atmospheric spectroscopy

    NASA Astrophysics Data System (ADS)

    Soldatov, A. N.; Mirza, S. Y.; Polunin, Yu. P.; Shumeiko, A. S.; Kostadinov, I. K.

    2015-11-01

    Results of a cycle of experimental investigations of a multi-wavelength metal vapor laser system based on original configuration of a multi-medium metal vapor laser source are presented. Novelty of our approach consists in that two gas-discharge active elements (on copper bromide and strontium vapors) are arranged in a common cavity, and each of them is pumped by an independent power supply unit, which allows them to be optimized independently for excitation conditions and thereby the output set of lasing wavelengths and their relative power distribution to be regulated. This makes the above-described system promising for a number of scientific and technological applications. The total output power of 11 spectral components lying in the range 0.43-6.45 μm reached ~17 W.

  1. Aerosol Properties over Southeastern China from Multi-Wavelength Raman and Depolarization Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Heese, Birgit; Althausen, Dietrich; Baars, Holger; Bohlmann, Stephanie; Deng, Ruru

    2016-06-01

    A dataset of particle optical properties of highly polluted urban aerosol over the Pearl River Delta, Guangzhou, China is presented. The data were derived from multi-wavelengths Raman and depolarization lidar PollyXT and AERONET sun photometer measurements. The measurement campaign was conducted from Nov 2011 to June 2012. High aerosol optical depth was observed in the polluted atmosphere over this megacity, with a mean value of 0.54 ± 0.33 and a peak value of even 1.9. For the particle characterization the lidar ratio and the linear particle depolarization ratio, both at 532 nm, were used. The mean values of these properties are 48.0 sr ± 10.7 sr for the lidar ratio and 4%+-4% for the particle depolarization ratio, which means most depolarization measurements stayed below 10%. So far, most of these results indicate urban pollution particles mixed with particles arisen from biomass and industrial burning.

  2. Electro-optically tunable, multi-wavelength optical parametric generators in aperiodically poled lithium niobates.

    PubMed

    Chen, Y H; Chung, H P; Chang, W K; Lyu, H T; Chang, J W; Tseng, C H

    2012-12-17

    We report on the design and demonstration of electro-optically tunable, multi-wavelength optical parametric generators (OPGs) based on aperiodically poled lithium niobate (APPLN) crystals. Two methods have been proposed to significantly enhance the electro-optic (EO) tunability of an APPLN OPG constructed by the aperiodic optical superlattice (AOS) technique. This is done by engineering the APPLN domain structure either in the crystal fabrication or in the crystal design process to increase the length or block-number difference of the two opposite-polarity domains used in the structure. Several orders of magnitude enhancement on the EO tuning rate of the APPLN OPGs constructed by the proposed techniques for simultaneous multiple signal wavelength generation over a conventional one has been demonstrated in a near infrared band (1500-1600 nm). PMID:23263140

  3. Development of SAC-OCDMA in FSO with multi-wavelength laser source

    NASA Astrophysics Data System (ADS)

    Moghaddasi, Majid; Mamdoohi, Ghazaleh; Muhammad Noor, Ahmad Shukri; Mahdi, Mohd Adzir; Ahmad Anas, Siti Barirah

    2015-12-01

    We propose and demonstrate a free space optical network, based on spectral amplitude coding optical code division multiple access (SAC-OCDMA) with a multi-wavelength laser source. A detailed theoretical analysis that represents the characteristics of SAC-OCDMA system was developed. In addition to the impact of turbulence, influences of several system noises such as optical beat interference (OBI), relative intensity noise, and receiver noises, have been studied. From the numerical results, it was found that the influence of OBI is more dominant, especially at higher received power. Two different codes, namely, modified quadratic congruence and modified double weight, are then compared with the latter which provides better performance. A transmission distance of 2.6 km with 10 users and an 8 cm aperture diameter is advisable whenever the turbulence is moderate. These results can be improved when a beam divergence smaller than 1 mrad is utilized.

  4. High channel count and high precision channel spacing multi-wavelength laser array for future PICs.

    PubMed

    Shi, Yuechun; Li, Simin; Chen, Xiangfei; Li, Lianyan; Li, Jingsi; Zhang, Tingting; Zheng, Jilin; Zhang, Yunshan; Tang, Song; Hou, Lianping; Marsh, John H; Qiu, Bocang

    2014-01-01

    Multi-wavelength semiconductor laser arrays (MLAs) have wide applications in wavelength multiplexing division (WDM) networks. In spite of their tremendous potential, adoption of the MLA has been hampered by a number of issues, particularly wavelength precision and fabrication cost. In this paper, we report high channel count MLAs in which the wavelengths of each channel can be determined precisely through low-cost standard μm-level photolithography/holographic lithography and the reconstruction-equivalent-chirp (REC) technique. 60-wavelength MLAs with good wavelength spacing uniformity have been demonstrated experimentally, in which nearly 83% lasers are within a wavelength deviation of ±0.20 nm, corresponding to a tolerance of ±0.032 nm in the period pitch. As a result of employing the equivalent phase shift technique, the single longitudinal mode (SLM) yield is nearly 100%, while the theoretical yield of standard DFB lasers is only around 33.3%. PMID:25488111

  5. OQ208: a possible multi-wavelength polarimetric study with the SRT

    NASA Astrophysics Data System (ADS)

    Cenacchi, E.; Dallacasa, D.; Orfei, A.

    We consider a possible contribution of the Sardinia Radio Telescope (SRT) to the polarimetric study of discrete sources. The foreseen capabilities are applied to the study of GHz-Peaked Spectrum (GPS) sources. The polarisation properties of these sources can be used to discriminate the absorption mechanism involved: Synchrotron Self Absorpion (SSA) would cause a change in the polarisation angle of 90° across the spectral peak, while Free-Free Absorption (FFA) would not. An accurate multi-wavelength polarimetric study could be carried out with the SRT and we apply the SRT specifications to a fake source with the radio spectrum identical to OQ208, and with a constant (unrealistic) fractional polarisation of 0.01. Considerations on the use of the SRT for a sky survey at 22 GHz are also given.

  6. Development of Multi-Wavelength Raman Lidar and its Application on Aerosol and Cloud Research

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Wang, Yingjian; Wang, Zhenzhu; Tao, Zongming; Wu, Decheng; Wang, Bangxin; Zhong, Zhiqing; Xie, Chenbo

    2016-06-01

    A movable multi-wavelength Raman lidar (TMPRL) was built in Hefei, China. Emitting with three wavelengths at 1064, 532, and 355nm, receiving three above Mie scattering signals and two nitrogen Raman signals at 386 and 607nm, and depolarization signal at 532nm, TMPRL has the capacity to investigate the height resolved optical and microphysical properties of aerosol and cloud. The retrieval algorithms of optical parameters base on Mie-Raman technique and the microphysical parameters based on Bayesian optimization method were also developed and applied to observed lidar data. Designing to make unattended operation and 24/7 continuous working, TMPRL has joined several field campaigns to study on the aerosol, cloud and their interaction researches. Some observed results of aerosol and cloud optical properties and the first attempt to validate the vertical aerosol size distribution retrieved by TMPRL and in-situ measurement by airplane are presented and discussed.

  7. Multi-wavelength pulse plethysmography for real-time drug delivery monitoring

    NASA Astrophysics Data System (ADS)

    Adhikari, Pratik; Magaña, Isidro B.; O'Neal, Patrick D.

    2014-02-01

    A novel multi-wavelength photoplethysmograph (PPG), previously utilized to quantify optically absorptive circulating gold nanoparticles, has demonstrated the potential to enhance therapeutic treatment predictability as pharmacokinetic metrics are provided throughout the intravenous delivery phase of quinine in real-time. This report demonstrates how the PPG could be used to assess the real-time bioavailability of other types of intravenously delivered optically-absorbing nanoparticles and drugs. The drug currently under investigation is anti-malarial quinine (absorption peak ~350 nm). We describe how the algorithm has been adapted to quantify the concentration of quinine in the pulsatile, circulating blood based on its extinction at three wavelengths (340, 660 and 940 nm). We show an example of the system collecting data representing the baseline, injection, and the clearance phases. An examination of the raw signal suggests that the system is well suited to sense the concentration of quinine in the therapeutic range (10mg/kg).

  8. Mass specific optical absorption coefficients of mineral dust components measured by a multi wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Utry, N.; Ajtai, T.; Pintér, M.; Tombácz, E.; Illés, E.; Bozóki, Z.; Szabó, G.

    2014-09-01

    Mass specific optical absorption coefficients of various mineral dust components including silicate clays (illite, kaolin and bentonite), oxides (quartz, hematite and rutile), and carbonate (limestone) were determined at wavelengths of 1064, 532, 355 and 266 nm. These values were calculated from aerosol optical absorption coefficients measured by a multi-wavelength photoacoustic (PA) instrument, the mass concentration and the number size distribution of the generated aerosol samples as well as the size transfer functions of the measuring instruments. These results are expected to have considerable importance in global radiative forcing calculations. They can also serve as reference for validating calculated wavelength dependent imaginary parts (κ) of complex refractive indices which up to now have been typically deduced from bulk phase measurements by using indirect measurement methods. Accordingly, the presented comparison of the measured and calculated aerosol optical absorption spectra revealed the strong need for standardized sample preparation and measurement methodology in case of bulk phase measurements.

  9. Multi-wavelength measurements of aerosol optical absorption coefficients using a photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Liu, Qiang; Huang, Hong-Hua; Wang, Yao; Wang, Gui-Shi; Cao, Zhen-Song; Liu, Kun; Chen, Wei-Dong; Gao, Xiao-Ming

    2014-06-01

    The atmospheric aerosol absorption capacity is a critical parameter determining its direct and indirect effects on climate. Accurate measurement is highly desired for the study of the radiative budget of the Earth. A multi-wavelength (405 nm, 532 nm, 780 nm) aerosol absorption meter based on photoacoustic spectroscopy (PAS) invovling a single cylindrical acoustic resonator is developed for measuring the aerosol optical absorption coefficients (OACs). A sensitivity of 1.3 Mm-1 (at 532 nm) is demonstrated. The aerosol absorption meter is successfully tested through measuring the OACs of atmospheric nigrosin and ambient aerosols in the suburbs of Hefei city. The absorption cross section and absorption Ångström exponent (AAE) for ambient aerosol are determined for characterizing the component of the ambient aerosol.

  10. Multi-wavelength Observations of Fast Infrared Flares from V404 Cygni in 2015

    NASA Astrophysics Data System (ADS)

    Eikenberry, Stephen S.; Dallilar, Yigit; Garner, Alan; Deno Stelter, R.; Gandhi, Poshak; Dhillon, Vik; Littlefair, Stuart; Marsh, Thomas; Fender, Rob P.; Mooley, Kunal

    2016-04-01

    We used the fast photometry mode of our new Canarias InfraRed Camera Experiment (CIRCE) on the 10.4-meter Gran Telescopio Canarias to observe V404 Cyg, a stellar mass black hole binary, on June 25, 2015 during its 2015 outburst. CIRCE provided 10Hz sampling in the Ks-band (2.2 microns) In addition, we obtained simultaneous multi wavelength data from our collaborators: three GHz radio bands from the AMI telescope and three optical/UV bands (u', g', r') from ULTRACAM on the William Herschel 4.2-meter telescope. We identify fast (1-second) IR flares with optical counterparts of varying strength/color, which we argue arise from a relativistic jet outflow. These observations provide important constraints on the emission processes and physical conditions in the jet forming region in V404 Cygni. We will discuss these results as well as their implications for relativistic jet formation around stellar-mass black holes.

  11. Low-threshold and multi-wavelength Q-switched random erbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Wang, Simin; Lin, Wei; Chen, Weicheng; Li, Can; Yang, Changsheng; Qiao, Tian; Yang, Zhongmin

    2016-03-01

    We demonstrate a low-threshold and multi-wavelength Q-switched random fiber laser with erbium-doped fiber as the gain medium and Rayleigh scattering as the randomly distributed feedback. Q-switched pulses are generated with threshold as low as 27 mW by combining random cavity resonances and the Q-value modulation effect induced by stimulated Brillouin scattering. The repetition rate is typically on the kilohertz scale with rms timing jitter of <5.5% and rms amplitude fluctuation of <30%. Raman Stokes emissions up to the third order are observed with an overall energy of nearly 42% of the pulse output, which may open an avenue for applications requiring multiple wavelengths.

  12. Multi-wavelength Raman scattering of nanostructured Al-doped zinc oxide

    SciTech Connect

    Russo, V.; Ghidelli, M.; Gondoni, P.

    2014-02-21

    In this work we present a detailed Raman scattering investigation of zinc oxide and aluminum-doped zinc oxide (AZO) films characterized by a variety of nanoscale structures and morphologies and synthesized by pulsed laser deposition under different oxygen pressure conditions. The comparison of Raman spectra for pure ZnO and AZO films with similar morphology at the nano/mesoscale allows to investigate the relation between Raman features (peak or band positions, width, relative intensity) and material properties such as local structural order, stoichiometry, and doping. Moreover Raman measurements with three different excitation lines (532, 457, and 325 nm) point out a strong correlation between vibrational and electronic properties. This observation confirms the relevance of a multi-wavelength Raman investigation to obtain a complete structural characterization of advanced doped oxide materials.

  13. Multi-channel multi-carrier generation using multi-wavelength frequency shifting recirculating loop.

    PubMed

    Li, Xinying; Yu, Jianjun; Dong, Ze; Zhang, Junwen; Shao, Yufeng; Chi, Nan

    2012-09-24

    We propose and experimentally demonstrate a novel scheme to generate optical frequency-locked multi-channel multi-carriers (MCMC), using a recirculating frequency shifter (RFS) loop based on multi-wavelength frequency shifting single side band (MWFS-SSB) modulation. In this scheme, optical subcarriers with multiple wavelengths can be generated each round. Furthermore, the generated MCMC are frequency- and phase-locked within each channel, and therefore can be effectively used for WDM superchannel. Dual-wavelength frequency shifting SSB modulation is carried out with dual-wavelength optical seed source in our experimental demonstration. Using this scheme, we successfully generate dual-channel multi-carriers, and one channel has 28 subcarriers while the other has 29 ones with 25-GHz subcarrier spacing. We also experimentally demonstrate that this kind of source can be used to carry 50-Gb/s optical polarization-division-multiplexing quadrature phase shift keying (PDM-QPSK) signal. PMID:23037333

  14. Multi-wavelength Observations of Fast Infrared Flares from V404 Cygni in 2015

    NASA Astrophysics Data System (ADS)

    Dallilar, Yigit; Casella, Piergiorgio; Marsh, Tom; Gandhi, Poshak; Fender, Rob; Littlefair, Stuart; Eikenberry, Steve; Garner, Alan; Stelter, Deno; Dhillon, Vik; Mooley, Kunal

    2016-07-01

    We used the fast photometry mode of our new Canarias InfraRed Camera Experiment (CIRCE) on the 10.4-meter Gran Telescopio Canarias to observe V404 Cyg, a stellar mass black hole binary, on June 25, 2015 during its 2015 outburst. CIRCE provided 10Hz sampling in the Ks-band (2.2 microns) In addition, we obtained simultaneous multi wavelength data from our collaborators: three GHz radio bands from the AMI telescope and three optical/UV bands (u', g', r') from ULTRACAM on the William Herschel 4.2-meter telescope. We identify fast (1-second) IR flares with optical counterparts of varying strength/color, which we argue arise from a relativistic jet outflow. These observations provide important constraints on the emission processes and physical conditions in the jet forming region in V404 Cygni. We will discuss these results as well as their implications for relativistic jet formation around stellar-mass black holes.

  15. Yangbajing Astronomical Observatory of NAOC in Tibet: a good multi-wavelength site

    NASA Astrophysics Data System (ADS)

    Wang, Jun-Jie

    2015-08-01

    Yangbajing Astronomical Station of National Astronomical Observatories, Chinese Academy of Science (NAOC) is located in Yangbajing Tibet (90°31'50" E 30°06'38" N, 4300m ). It is the first professional observatory operated by NAOC for science project in Tibet. This station was established on August 17, 2011, which means that Tibet has its first astronomical observatory. There are one 3-meter in diameter submillimeter telescope CCOSMA and five 40-50 cm optical telescopes. This could lay a solid foundation for attracting more international cooperation on large telescope projects in Tibet in future. we have already tested the radio, millimeter/submillimeter and optical environment in Yangbajing. The result shows that Yangbajing station is a good desirable multi-wavelength astronomical observation site.

  16. Demonstration of multi-wavelength tunable fiber lasers based on a digital micromirror device processor.

    PubMed

    Ai, Qi; Chen, Xiao; Tian, Miao; Yan, Bin-bin; Zhang, Ying; Song, Fei-jun; Chen, Gen-xiang; Sang, Xin-zhu; Wang, Yi-quan; Xiao, Feng; Alameh, Kamal

    2015-02-01

    Based on a digital micromirror device (DMD) processor as the multi-wavelength narrow-band tunable filter, we demonstrate a multi-port tunable fiber laser through experiments. The key property of this laser is that any lasing wavelength channel from any arbitrary output port can be switched independently over the whole C-band, which is only driven by single DMD chip flexibly. All outputs display an excellent tuning capacity and high consistency in the whole C-band with a 0.02 nm linewidth, 0.055 nm wavelength tuning step, and side-mode suppression ratio greater than 60 dB. Due to the automatic power control and polarization design, the power uniformity of output lasers is less than 0.008 dB and the wavelength fluctuation is below 0.02 nm within 2 h at room temperature. PMID:25967765

  17. High channel count and high precision channel spacing multi-wavelength laser array for future PICs

    PubMed Central

    Shi, Yuechun; Li, Simin; Chen, Xiangfei; Li, Lianyan; Li, Jingsi; Zhang, Tingting; Zheng, Jilin; Zhang, Yunshan; Tang, Song; Hou, Lianping; Marsh, John H.; Qiu, Bocang

    2014-01-01

    Multi-wavelength semiconductor laser arrays (MLAs) have wide applications in wavelength multiplexing division (WDM) networks. In spite of their tremendous potential, adoption of the MLA has been hampered by a number of issues, particularly wavelength precision and fabrication cost. In this paper, we report high channel count MLAs in which the wavelengths of each channel can be determined precisely through low-cost standard μm-level photolithography/holographic lithography and the reconstruction-equivalent-chirp (REC) technique. 60-wavelength MLAs with good wavelength spacing uniformity have been demonstrated experimentally, in which nearly 83% lasers are within a wavelength deviation of ±0.20 nm, corresponding to a tolerance of ±0.032 nm in the period pitch. As a result of employing the equivalent phase shift technique, the single longitudinal mode (SLM) yield is nearly 100%, while the theoretical yield of standard DFB lasers is only around 33.3%. PMID:25488111

  18. The astrocosmic databases for multi-wavelength and cosmological properties of extragalactic sources

    NASA Astrophysics Data System (ADS)

    Vavilova, I. B.; Ivashchenko, G. Yu.; Babyk, Yu. V.; Sergijenko, O.; Dobrycheva, D. V.; Torbaniuk, O. O.; Vasylenko, A. A.; Pulatova, N. G.

    2015-12-01

    The article briefly describes the new specially-oriented Astro Space databases obtained with ground-based telescopes and space observatories. As a result, multi-wavelength spectral and physical properties of galaxies and galaxy clusters were analyzed in more details, particularly 1) to study the spectral properties of quasars and the distribution of matter in intergalactic scales using Lyman-alpha forest; 2) to study galaxies (including with active nuclei), especially for the formation of large-scale structures in the Universe and influence of the environment on the internal parameters of galaxies; 3) to estimate a visible and dark matter content in galaxy clusters and to test cosmological parameters and the evolution of matter in a wide range of age of the Universe.

  19. A Multi-wavelength campaign to study the Jovian aurora and the Io plasma torus

    NASA Astrophysics Data System (ADS)

    Murray, Stephen

    2013-09-01

    We request 2 40ks HRC-I observations of Jupiter to be made in Apr 2014 in support of the SPRINT-A mission to study the Jovian aurora and the Io plasma torus. SPRINT-A will make sensitive EUV spectroscopic measurements of the upper atmospheres and magnetospheres of planets in the Solar system. The coordinated multi-wavelength campaign to observe the Jovian auroras and the Io plasma torus will provide an unprecedented study of the plasma content of the Jovian magnetosphere. Our X-ray observations will monitor the flux and morphology of the tens to hundreds of eV thermal plasma in the aurora and magnetosphere, and our coordinated observations will determine whether outflows from Io or interaction with the Solar wind are responsible for creating this hot, X-ray emitting plasma.

  20. The 2010 Eruption of the Recurrent Nova U Scorpii: The Multi-wavelength Light Curve

    NASA Astrophysics Data System (ADS)

    Pagnotta, Ashley; Schaefer, Bradley E.; Clem, James L.; Landolt, Arlo U.; Handler, Gerald; Page, Kim L.; Osborne, Julian P.; Schlegel, Eric M.; Hoffman, Douglas I.; Kiyota, Seiichiro; Maehara, Hiroyuki

    2015-09-01

    The recurrent nova U Scorpii most recently erupted in 2010. Our collaboration observed the eruption in bands ranging from the Swift XRT and UVOT w2 (193 nm) to K-band (2200 nm), with a few serendipitous observations stretching down to WISE W2 (4600 nm). Considering the time and wavelength coverage, this is the most comprehensively observed nova eruption to date. We present here the resulting multi-wavelength light curve covering the two months of the eruption as well as a few months into quiescence. For the first time, a U Sco eruption has been followed all the way back to quiescence, leading to the discovery of new features in the light curve, including a second, as-yet-unexplained, plateau in the optical and near-infrared. Using this light curve we show that U Sco nearly fits the broken power law decline predicted by Hachisu & Kato, with decline indices of -1.71 ± 0.02 and -3.36 ± 0.14. With our unprecedented multi-wavelength coverage, we construct daily spectral energy distributions and then calculate the total radiated energy of the eruption, {E}{rad}={6.99}-0.57+0.83× {10}44 {erg}. From that, we estimate the total amount of mass ejected by the eruption to be {m}{ej}={2.10}-0.17+0.24× {10}-6{M}⊙ . We compare this to the total amount of mass accreted by U Sco before the eruption, to determine whether the white dwarf undergoes a net mass loss or gain, but find that the values for the amount of mass accreted are not precise enough to make a useful comparison.

  1. Multi-wavelength Raman Spectroscopic Study of Silica-supported Vanadium Oxide Catalysts

    SciTech Connect

    Wu, Zili; Dai, Sheng; Overbury, Steven {Steve} H

    2010-01-01

    The molecular structure of silica-supported vanadium oxide (VOx) catalysts over wide range of surface VOx density (0.0002 8 V/nm2) has been investigated in detail under dehydrated condition by in situ multi-wavelength Raman spectroscopy (laser excitations at 244, 325, 442, 532, and 633 nm) and in situ UV-Vis diffuse reflectance spectroscopy. Resonance Raman scattering is clearly observed using 244 and 325-nm excitations while normal Raman scattering occurs using excitation at the three visible wavelengths. The observation of strong fundamentals, overtones and combinational bands due to selective resonance enhancement effect helps clarify assignments of some of the VOx Raman bands (920, 1032, and 1060 cm-1) whose assignments have been controversial. The resonance Raman spectra of dehydrated VOx/SiO2 show V=O band at smaller Raman shift than that in visible Raman spectra, an indication of the presence of two different surface VOx species on dehydrated SiO2 even at sub-monolayer VOx loading. Quantitative estimation shows that the two different monomeric VOx species coexist on silica surface from very low VOx loadings and transform to crystalline V2O5 at VOx loadings above monolayer. It is postulated that one of the two monomeric VOx species has pyramidal structure and the other is in partially hydroxylated pyramidal mode. The two VOx species show similar reduction-oxidation behavior and may both participate in redox reactions catalyzed by VOx/SiO2 catalysts. This study demonstrates the advantages of multi-wavelength Raman spectroscopy over conventional single-wavelength Raman spectroscopy in structural characterization of supported metal oxide catalysts.

  2. A multi-wavelength fiber laser based on superimposed fiber grating and chirp fiber Bragg grating for wavelength selection

    NASA Astrophysics Data System (ADS)

    Wang, Feng; Bi, Wei-hong; Fu, Xing-hu; Jiang, Peng; Wu, Yang

    2015-11-01

    In this paper, a new type of multi-wavelength fiber laser is proposed and demonstrated experimentally. Superimposed fiber grating (SIFG) and chirp fiber Bragg grating (CFBG) are used for wavelength selection. Based on gain equalization technology, by finely adjusting the stress device in the cavity, the gain and loss are equal, so as to suppress the modal competition and achieve multi-wavelength lasing at room temperature. The experimental results show that the laser can output stable multi-wavelength lasers simultaneously. The laser coupling loss is small, the structure is simple, and it is convenient for integration, so it can be widely used in dense wavelength division multiplexing (DWDM) system and optical fiber sensors.

  3. Measurement dimensions compressed spectral imaging with a single point detector

    NASA Astrophysics Data System (ADS)

    Liu, Xue-Feng; Yu, Wen-Kai; Yao, Xu-Ri; Dai, Bin; Li, Long-Zhen; Wang, Chao; Zhai, Guang-Jie

    2016-04-01

    An experimental demonstration of spectral imaging with measurement dimensions compressed has been performed. With the method of dual compressed sensing (CS) we derive, the spectral image of a colored object can be obtained with only a single point detector, and sub-sampling is achieved in both spatial and spectral domains. The performances of dual CS spectral imaging are analyzed, including the effects of dual modulation numbers and measurement noise on the imaging quality. Our scheme provides a stable, high-flux measurement approach of spectral imaging.

  4. A resonance ionization imaging detector based on cesium atomic vapor

    NASA Astrophysics Data System (ADS)

    Temirov, J. P.; Chigarev, N. V.; Matveev, O. I.; Omenetto, N.; Smith, B. W.; Winefordner, J. D.

    2004-05-01

    A novel Cs resonance ionization imaging detector (RIID) has been developed and evaluated. The detector is capable of two-dimensional imaging with high spectral resolution, which is determined by the Doppler broadened atomic linewidth of Cs at given temperature. Ionization schemes of Cs have been investigated using dye and color center tunable lasers pumped by an excimer laser and by a Nd:YAG laser. It has been experimentally shown that the most efficient ionization scheme for Cs RIID should include a three-step excitation/ionization ladder, for example, with transitions at λ1=852.11 (852.113) nm, λ2=917.22 (917.2197) nm, and λ3=1064 nm. The imaging capabilities of the detector have been evaluated using a simpler two-step ionization scheme with wavelengths λ1=852.11 nm and λ2=508 nm.

  5. A ring imaging Cherenkov detector for CLAS12

    SciTech Connect

    Montgomery, Rachel A.

    2013-12-01

    The energy increase of Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) to 12 GeV promises to greatly extend the physics reach of its experiments. This will include an upgrade of the CEBAF Large Acceptance Spectrometer (CLAS) to CLAS12, offering unique possibilities to study internal nucleon dynamics. For this excellent hadron identification over the full kinematical range of 3–8 GeV/c is essential. This will be achieved by the installation of a Ring Imaging CHerenkov (RICH) detector. A novel hybrid imaging design incorporating mirrors, aerogel radiators and Hamamatsu H8500 multianode photomultiplier tubes is proposed. Depending on the incident particle track angle, Cherenkov light will either be imaged directly or after two reflections and passes through the aerogel. The detector design is described, along with preliminary results on individual detector components tests and from recent testbeam studies.

  6. Astronomical imaging with infrared array detectors.

    PubMed

    Gatley, I; Depoy, D L; Fowler, A M

    1988-12-01

    History shows that progress in astronomy often stems directly from technological innovation and that each portion of the electromagnetic spectrum offers unique insights into the nature of the universe. Most recently, the widespread availability of infrared-sensitive two-dimensional array detectors has led to dramatic improvements in the capabilities of conventional ground-based observatories. The impact of this new technology on our understanding of a wide variety of phenomena is illustrated here by infrared pictures of star-forming regions, of nebulae produced by the late stages of stellar evolution, of the nucleus of our own galaxy(the Milky Way), and of activity in other galaxies. PMID:17817072

  7. Spectral X-Ray Diffraction using a 6 Megapixel Photon Counting Array Detector

    PubMed Central

    Muir, Ryan D.; Pogranichniy, Nicholas R.; Muir, J. Lewis; Sullivan, Shane Z.; Battaile, Kevin P.; Mulichak, Anne M.; Toth, Scott J.; Keefe, Lisa J.; Simpson, Garth J.

    2016-01-01

    Pixel-array array detectors allow single-photon counting to be performed on a massively parallel scale, with several million counting circuits and detectors in the array. Because the number of photoelectrons produced at the detector surface depends on the photon energy, these detectors offer the possibility of spectral imaging. In this work, a statistical model of the instrument response is used to calibrate the detector on a per-pixel basis. In turn, the calibrated sensor was used to perform separation of dual-energy diffraction measurements into two monochromatic images. Targeting applications include multi-wavelength diffraction to aid in protein structure determination and X-ray diffraction imaging. PMID:27041789

  8. Development and performance of a gamma-ray imaging detector

    NASA Astrophysics Data System (ADS)

    Gálvez, J. L.; Hernanz, M.; Álvarez, J. M.; La Torre, M.; Álvarez, L.; Karelin, D.; Lozano, M.; Pellegrini, G.; Ullán, M.; Cabruja, E.; Martínez, R.; Chmeissani, M.; Puigdengoles, C.

    2012-09-01

    In the last few years we have been working on feasibility studies of future instruments in the gamma-ray range, from several keV up to a few MeV. The innovative concept of focusing gamma-ray telescopes in this energy range, should allow reaching unprecedented sensitivities and angular resolution, thanks to the decoupling of collecting area and detector volume. High sensitivities are essential to perform detailed studies of cosmic explosions and cosmic accelerators, e.g., Supernovae, Classical Novae, Supernova Remnants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, Active Galactic Nuclei (AGN). In order to achieve the needed performance, a gamma-ray imaging detector with mm spatial resolution and large enough efficiency is required. In order to fulfill the combined requirement of high detection efficiency with good spatial and energy resolution, an initial prototype of a gamma-ray imaging detector based on CdTe pixel detectors is being developed. It consists of a stack of several layers of CdTe detectors with increasing thickness, in order to enhance the gamma-ray absorption in the Compton regime. A CdTe module detector lies in a 11 x 11 pixel detector with a pixel pitch of 1mm attached to the readout chip. Each pixel is bump bonded to a fan-out board made of alumina (Al2O3) substrate and routed to the corresponding input channel of the readout ASIC to measure pixel position and pulse height for each incident gamma-ray photon. We will report the main features of the gamma-ray imaging detector performance such as the energy resolution for a set of radiation sources at different operating temperatures.

  9. The RoF-WDM-PON for Wireless and Wire Layout with Multi-wavelength Fiber Laser and Carrier Reusing

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Zheng, Zhuowen

    2013-09-01

    In this paper, we design a WDM-RoF-PON based on multi-wavelength fiber laser and CSRZ-DPSK, which can achieve wire-line and wireless access synchronously without any RF source in ONU. The multi-wavelength fiber laser is the union light source of WDM-PON. By the RSOA and downstream light source reusing, the ONU can also omit laser source and makes the WDM-PON to be colorless. The networking has the credible transmission property, including wireless access and fiber transmission. The networking also has excellent covering range.

  10. Mode switching in a multi-wavelength distributed feedback quantum cascade laser using an external micro-cavity

    SciTech Connect

    Sidler, Meinrad; Rauter, Patrick; Blanchard, Romain; Métivier, Pauline; Capasso, Federico; Mansuripur, Tobias S.; Wang, Christine; Huang, Yong; Ryou, Jae-Hyun; Dupuis, Russell D.; Faist, Jérôme

    2014-02-03

    We demonstrate a multi-wavelength distributed feedback (DFB) quantum cascade laser (QCL) operating in a lensless external micro-cavity and achieve switchable single-mode emission at three distinct wavelengths selected by the DFB grating, each with a side-mode suppression ratio larger than 30 dB. Discrete wavelength tuning is achieved by modulating the feedback experienced by each mode of the multi-wavelength DFB QCL, resulting from a variation of the external cavity length. This method also provides a post-fabrication control of the lasing modes to correct for fabrication inhomogeneities, in particular, related to the cleaved facets position.

  11. The PICASSO digital detector for Diffraction Enhanced Imaging at ELETTRA

    SciTech Connect

    Arfelli, F.; Longo, R.; Castelli, E.; Astolfo, A.; Menk, R.-H.; Rigon, L.; Vallazza, E.; Zanconati, F.; De Pellegrin, A.; Chen, R. C.; Dreossi, D.

    2010-07-23

    A clinical mammography program is in progress at the medical beamline SYRMEP of the Italian synchrotron radiation laboratory ELETTRA in Trieste. A conventional screen-film system is utilized as detector for the examinations on patients. For the next experimental step a digital detector has been designed taking into account the essential requirements for mammography such as high spatial and contrast resolution, high efficiency for low dose examinations and high speed for short acquisition time. A double-layer prototype has already been tested in the frame of the PICASSO project. In addition, an analyzer crystal set-up for Diffraction Enhanced Imaging (DEI) has been available for many years at the SYRMEP beamline. Applying the DEI technique several successful experiments have been carried out in biomedical imaging and in particular in-vitro breast imaging utilizing commercially available detectors. Recently a system upgrade yielded a double-crystal analyzer set-up with improved stability and higher angular resolution. In this study the PICASSO detector has been utilized in combination with the new analyzer set-up for imaging in-vitro breast tissue samples. In order to test the potential of the combined system planar and tomographic images have been acquired and the first results are here presented.

  12. The PICASSO digital detector for Diffraction Enhanced Imaging at ELETTRA

    NASA Astrophysics Data System (ADS)

    Arfelli, F.; Astolfo, A.; Menk, R.-H.; Rigon, L.; Zanconati, F.; De Pellegrin, A.; Chen, R. C.; Dreossi, D.; Longo, R.; Vallazza, E.; Castelli, E.

    2010-07-01

    A clinical mammography program is in progress at the medical beamline SYRMEP of the Italian synchrotron radiation laboratory ELETTRA in Trieste. A conventional screen-film system is utilized as detector for the examinations on patients. For the next experimental step a digital detector has been designed taking into account the essential requirements for mammography such as high spatial and contrast resolution, high efficiency for low dose examinations and high speed for short acquisition time. A double-layer prototype has already been tested in the frame of the PICASSO project. In addition, an analyzer crystal set-up for Diffraction Enhanced Imaging (DEI) has been available for many years at the SYRMEP beamline. Applying the DEI technique several successful experiments have been carried out in biomedical imaging and in particular in-vitro breast imaging utilizing commercially available detectors. Recently a system upgrade yielded a double-crystal analyzer set-up with improved stability and higher angular resolution. In this study the PICASSO detector has been utilized in combination with the new analyzer set-up for imaging in-vitro breast tissue samples. In order to test the potential of the combined system planar and tomographic images have been acquired and the first results are here presented.

  13. Design considerations for ultrasound detectors in photoacoustic breast imaging

    NASA Astrophysics Data System (ADS)

    Xia, Wenfeng; Piras, Daniele; Singh, Mithun K. A.; van Hespen, Johan C. G.; van Veldhoven, Spiridon; Prins, Christian; van Leeuwen, Ton G.; Steenbergen, Wiendelft; Manohar, Srirang

    2013-03-01

    The ultrasound detector is the heart of a photoacoustic imaging system. In photoacoustic imaging of the breast there is a requirement to detect tumors located a few centimeters deep in tissue, where the light is heavily attenuated. Thus a sensitive ultrasound transducer is of crucial importance. As the frequency content of photoacoustic waves are inversely proportional to the dimensions of the absorbing structures, and in tissue can range from hundreds of kHz to tens of MHz, a broadband ultrasound transducer is required centered on an optimum frequency. A single element piezoelectric transducer structurally consists of the active piezoelectric material, front- and back-matching layers and a backing layer. To have both high sensitivity and broad bandwidth, the materials, their acoustic characteristics and their dimensions should be carefully chosen. In this paper, we present design considerations of an ultrasound transducer for imaging the breast such as the detector sensitivity and frequency response, which guides the selection of active material, matching layers and their geometries. We iterate between simulation of detector performance and experimental characterization of functional models to arrive at an optimized implementation. For computer simulation, we use 1D KLM and 3D finite-element based models. The optimized detector has a large-aperture possessing a center frequency of 1 MHz with fractional bandwidth of more than 80%. The measured minimum detectable pressure is 0.5 Pa, which is two orders of magnitude lower than the detector used in the Twente photoacoustic mammoscope.

  14. Velocity map imaging using an in-vacuum pixel detector

    NASA Astrophysics Data System (ADS)

    Gademann, Georg; Huismans, Ymkje; Gijsbertsen, Arjan; Jungmann, Julia; Visschers, Jan; Vrakking, Marc J. J.

    2009-10-01

    The use of a new type in-vacuum pixel detector in velocity map imaging (VMI) is introduced. The Medipix2 and Timepix semiconductor pixel detectors (256×256 square pixels, 55×55 μm2) are well suited for charged particle detection. They offer high resolution, low noise, and high quantum efficiency. The Medipix2 chip allows double energy discrimination by offering a low and a high energy threshold. The Timepix detector allows to record the incidence time of a particle with a temporal resolution of 10 ns and a dynamic range of 160 μs. Results of the first time application of the Medipix2 detector to VMI are presented, investigating the quantum efficiency as well as the possibility to operate at increased background pressure in the vacuum chamber.

  15. A multi-wavelength scattered light analysis of the dust grain population in the GG Tau circumbinary ring

    SciTech Connect

    Duchene, G; McCabe, C; Ghez, A; Macintosh, B

    2004-02-04

    We present the first 3.8 {micro}m image of the dusty ring surrounding the young binary system GG Tau, obtained with the W. M. Keck II 10m telescope's adaptive optics system. THis is the longest wavelength at which the ring has been detected in scattered light so far, allowing a multi-wavelength analysis of the scattering proiperties of the dust grains present in this protoplanetary disk in combination with previous, shorter wavelengths, HST images. We find that the scattering phase function of the dust grains in the disk is only weakly dependent on the wavelength. This is inconsistent with dust models inferred from observations of the interstellar medium or dense molecular clouds. In particular, the strongly forward-throwing scattering phase function observed at 3.8 {micro}m implies a significant increase in the population of large ({approx}> 1 {micro}m) grains, which provides direct evidence for grain growth in the ring. However, the grain size distribution required to match the 3.8 {micro}m image of the ring is incompatible with its published 1 {micro}m polarization map, implying that the dust population is not uniform throughout the ring. We also show that our 3.8 {micro}m image of the ring is incompatible with its published 1 {micro}m polarization map, implying that the dust population is not uniform throughout the ring. We also show that our 3.8 {micro}m scattered light image probes a deeper layer of the ring than previous shorter wavelength images, as demonstrated by a shift in the location of the inner edge of the disk's scattered light distribution between 1 and 3.8 {micro}m. We therefore propose a stratified structure for the ring in which the surface layers, located {approx} 50 AU above the ring midplane, contain dust grains that are very similar to those found in dense molecular clouds, while the region of the ring located {approx} 25 AU from the midplane contains significantly larger grains. This stratified structure is likely the result of vertical

  16. Development of high resolution imaging detectors for x ray astronomy

    NASA Technical Reports Server (NTRS)

    Murray, S. S.; Schwartz, D. A.

    1992-01-01

    This final report summarizes our past activities and discusses the work performed over the period of 1 April 1990 through 1 April 1991 on x-ray optics, soft x-ray (0.1 - 10 KeV) imaging detectors, and hard x-ray (10 - 300 KeV) imaging detectors. If microchannel plates (MCPs) can be used to focus x-rays with a high efficiency and good angular resolution, they will revolutionize the field of x-ray optics. An x-ray image of a point source through an array of square MCP pores compared favorably with our ray tracing model for the MCP. Initial analysis of this image demonstrates the feasibility of MCPs for soft x-rays. Our work continues with optimizing the performance of our soft x-ray MCP imaging detectors. This work involves readout technology that should provide improved MCP readout devices (thin film crossed grid, curved, and resistive sheets), defect removal in MCPs, and photocathode optimization. In the area of hard x-ray detector development we have developed two different techniques for producing a CsI photocathode thickness of 10 to 100 microns, such that it is thick enough to absorb the high energy x-rays and still allow the photoelectrons to escape to the top MCP of a modified soft x-ray imaging detector. The methods involve vacuum depositing a thick film of CsI on a strong back, and producing a converter device that takes the place of the photocathode.

  17. A Compact Imaging Detector of Polarization and Spectral Content

    NASA Technical Reports Server (NTRS)

    Rust, D. M.; Kumar, A.; Thompson, K. E.

    1993-01-01

    A new type of image detector will simultaneously analyze the polarization of light at all picture elements in a scene. The integrated Dual Imaging Detector (IDID) consists of a polarizing beam splitter bonded to a charge-coupled device (CCD), with signal-analysis circuitry and analog-to-digital converters, all integrated on a silicon chip. The polarizing beam splitter can be either a Ronchi ruling, or an array of cylindrical lenslets, bonded to a birefringent wafer. The wafer, in turn, is bonded to the CCD so that light in the two orthogonal planes of polarization falls on adjacent pairs of pixels. The use of a high-index birefringent material, e.g., rutile, allows the IDID to operate at f-numbers as high as f/3.5. Other aspects of the detector are discussed.

  18. A compact imaging detector of polarization and spectral content

    NASA Astrophysics Data System (ADS)

    Rust, D. M.; Kumar, A.; Thompson, K. E.

    A new type of image detector will simultaneously analyze the polarization of light at all picture elements in a scene. The integrated Dual Imaging Detector (IDID) consists of a polarizing beam splitter bonded to a charge-coupled device (CCD), with signal-analysis circuitry and analog-to-digital converters, all integrated on a silicon chip. The polarizing beam splitter can be either a Ronchi ruling, or an array of cylindrical lenslets, bonded to a birefringent wafer. The wafer, in turn, is bonded to the CCD so that light in the two orthogonal planes of polarization falls on adjacent pairs of pixels. The use of a high-index birefringent material, e.g., rutile, allows the IDID to operate at f-numbers as high as f/3.5. Other aspects of the detector are discussed.

  19. Detectors for single-molecule fluorescence imaging and spectroscopy

    PubMed Central

    MICHALET, X.; SIEGMUND, O.H.W.; VALLERGA, J.V.; JELINSKY, P.; MILLAUD, J.E.; WEISS, S.

    2010-01-01

    Single-molecule observation, characterization and manipulation techniques have recently come to the forefront of several research domains spanning chemistry, biology and physics. Due to the exquisite sensitivity, specificity, and unmasking of ensemble averaging, single-molecule fluorescence imaging and spectroscopy have become, in a short period of time, important tools in cell biology, biochemistry and biophysics. These methods led to new ways of thinking about biological processes such as viral infection, receptor diffusion and oligomerization, cellular signaling, protein-protein or protein-nucleic acid interactions, and molecular machines. Such achievements require a combination of several factors to be met, among which detector sensitivity and bandwidth are crucial. We examine here the needed performance of photodetectors used in these types of experiments, the current state of the art for different categories of detectors, and actual and future developments of single-photon counting detectors for single-molecule imaging and spectroscopy. PMID:20157633

  20. A low-energy gamma-ray imaging detector

    NASA Technical Reports Server (NTRS)

    Yin, L. I.; Trombka, J. I.; Seltzer, S. M.

    1979-01-01

    We describe a hard-X-ray/soft-gamma-ray imaging detector, incorporating a microchannel-plate (MCP) electron multiplier for possible use in future telescopes. In contrast to previous attempts using MCP's this approach promises to achieve high quantum detection efficiencies in addition to high spatial and temporal resolution. Preliminary results indicate not only the capability of simultaneous imaging and single-photon counting, but also coarse energy resolution.

  1. A novel phoswich imaging detector for simultaneous beta and coincidence-gamma imaging of plant leaves.

    PubMed

    Wu, Heyu; Tai, Yuan-Chuan

    2011-09-01

    To meet the growing demand for functional imaging technology for use in studying plant biology, we are developing a novel technique that permits simultaneous imaging of escaped positrons and coincidence gammas from annihilation of positrons within an intake leaf. The multi-modality imaging system will include two planar detectors: one is a typical PET detector array and the other is a phoswich imaging detector that detects both beta and gamma. The novel phoswich detector is made of a plastic scintillator, a lutetium oxyorthosilicate (LSO) array, and a position sensitive photomultiplier tube (PS-PMT). The plastic scintillator serves as a beta detector, while the LSO array serves as a gamma detector and light guide that couples scintillation light from the plastic detector to the PMT. In our prototype, the PMT signal was fed into the Siemens QuickSilver electronics to achieve shaping and waveform sampling. Pulse-shape discrimination based on the detectors' decay times (2.1 ns for plastic and 40 ns for LSO) was used to differentiate beta and gamma events using the common PMT signals. Using our prototype phoswich detector, we simultaneously measured a beta image and gamma events (in single mode). The beta image showed a resolution of 1.6 mm full-width-at-half-maximum using F-18 line sources. Because this shows promise for plant-scale imaging, our future plans include development of a fully functional simultaneous beta-and-coincidence-gamma imager with sub-millimeter resolution imaging capability for both modalities. PMID:21828901

  2. Speckle imaging with the MAMA detector: Preliminary results

    NASA Technical Reports Server (NTRS)

    Horch, E.; Heanue, J. F.; Morgan, J. S.; Timothy, J. G.

    1994-01-01

    We report on the first successful speckle imaging studies using the Stanford University speckle interferometry system, an instrument that uses a multianode microchannel array (MAMA) detector as the imaging device. The method of producing high-resolution images is based on the analysis of so-called 'near-axis' bispectral subplanes and follows the work of Lohmann et al. (1983). In order to improve the signal-to-noise ratio in the bispectrum, the frame-oversampling technique of Nakajima et al. (1989) is also employed. We present speckle imaging results of binary stars and other objects from V magnitude 5.5 to 11, and the quality of these images is studied. While the Stanford system is capable of good speckle imaging results, it is limited by the overall quantum efficiency of the current MAMA detector (which is due to the response of the photocathode at visible wavelengths and other detector properties) and by channel saturation of the microchannel plate. Both affect the signal-to-noise ratio of the power spectrum and bispectrum.

  3. A Multi-wavelength Polarimetric Study of the Blazar CTA 102 during a Gamma-Ray Flare in 2012

    NASA Astrophysics Data System (ADS)

    Casadio, Carolina; Gómez, José L.; Jorstad, Svetlana G.; Marscher, Alan P.; Larionov, Valeri M.; Smith, Paul S.; Gurwell, Mark A.; Lähteenmäki, Anne; Agudo, Iván; Molina, Sol N.; Bala, Vishal; Joshi, Manasvita; Taylor, Brian; Williamson, Karen E.; Arkharov, Arkady A.; Blinov, Dmitry A.; Borman, George A.; Di Paola, Andrea; Grishina, Tatiana S.; Hagen-Thorn, Vladimir A.; Itoh, Ryosuke; Kopatskaya, Evgenia N.; Larionova, Elena G.; Larionova, Liudmila V.; Morozova, Daria A.; Rastorgueva-Foi, Elizaveta; Sergeev, Sergey G.; Tornikoski, Merja; Troitsky, Ivan S.; Thum, Clemens; Wiesemeyer, Helmut

    2015-11-01

    We perform a multi-wavelength polarimetric study of the quasar CTA 102 during an extraordinarily bright γ-ray outburst detected by the Fermi Large Area Telescope in 2012 September-October when the source reached a flux of F>100 MeV = 5.2 ± 0.4 × 10-6 photons cm-2 s-1. At the same time, the source displayed an unprecedented optical and near-infrared (near-IR) outburst. We study the evolution of the parsec-scale jet with ultra-high angular resolution through a sequence of 80 total and polarized intensity Very Long Baseline Array images at 43 GHz, covering the observing period from 2007 June to 2014 June. We find that the γ-ray outburst is coincident with flares at all the other frequencies and is related to the passage of a new superluminal knot through the radio core. The powerful γ-ray emission is associated with a change in direction of the jet, which became oriented more closely to our line of sight (θ ˜ 1.°2) during the ejection of the knot and the γ-ray outburst. During the flare, the optical polarized emission displays intra-day variability and a clear clockwise rotation of electric vector position angles (EVPAs), which we associate with the path followed by the knot as it moves along helical magnetic field lines, although a random walk of the EVPA caused by a turbulent magnetic field cannot be ruled out. We locate the γ-ray outburst a short distance downstream of the radio core, parsecs from the black hole. This suggests that synchrotron self-Compton scattering of NIR to ultraviolet photons is the probable mechanism for the γ-ray production.

  4. Space and ground-based multi-wavelength observing campaign of Jupiter's aurora and the Io Plasma Torus

    NASA Astrophysics Data System (ADS)

    Branduardi-Raymont, G.; Yoshikawa, I.; Badman, S.

    2013-09-01

    The EXCEED EUV spectrograph (55 - 145 nm) on-board the Japanese mission Sprint-A, due for launch into low Earth orbit in August 2013, will be dedicated to the study of the tenuous plasma surrounding planets in our solar system. A target of special interest will be Jupiter and its environment, and the emission from the Io Plasma Torus (IPT) in particular. A systematic campaign of observations of Jupiter and the IPT is planned over the period Oct. 2013 - March 2014. This is a unique opportunity to explore the possible links between the IPT emission distribution, the strength and character of Jupiter's auroral emissions and the conditions of the solar wind. Hence, concurrently with the EXCEED observations, a large multi-wavelength campaign has been organised to exploit this unique opportunity of gathering important diagnostic data on the complex array of physical processes taking place in Jupiter's environment. This campaign includes (this is by no means a complete list) approved FUV imaging and spectroscopy of Jupiter's Northern aurora with HSTSTIS (PI: Sarah Badman), Kitt Peak 4m visible spectroscopy of the IPT (PI: Sarah Badman), Gemini observations of Jupiter H3+ (4 µm) aurora (PI: Melin), submitted proposals for HST-STIS FUV observations of Jupiter's Southern aurora, Io and Ganymede's footprints (PI: Bonfond), Chandra and XMM-Newton pointings of Jupiter and the IPT (PI: Kraft), Suzaku observations of diffuse X-rays from the Jovian inner magnetosphere (PI: Ezoe); in addition, ground based observations with IRTF, Subaru and other facilities are planned. This talk will review the motivation for this vaste coordinated observing campaign, and the science that we expect to draw from it: essentially a better understanding of how the Jupiter's system works.

  5. Virtual Sky Surveys and Multi-wavelength Investigations of Galaxy Clusters

    NASA Astrophysics Data System (ADS)

    Nord, Brian D.

    2010-12-01

    The advent of large and overlapping sky surveys brings promise of a new era in the study of galaxy clusters and dark energy. Clusters have been used for decades as faithful buoys of space-time, tracing cosmic evolution through their matter content and spatial distribution. High-fidelity tracking relies on a robust connection between observable cluster signatures and the underlying dark matter content, which is otherwise invisible. Until now, clusters have been mostly viewed through independent signals in distinct wavebands. The next era of cluster cosmology may be led by multi-variate, cross-waveband detections and analyses of clusters, where different facets of clusters can be cross-correlated to develop a more complete, unified picture of cluster populations. To these ends, in this dissertation, I perform multi-variate analyses of galaxy cluster populations and develop a simulated sky survey, with which to prepare for the next generation of multi-wavelength cluster observations. First, in a new multi-variate framework, I quantify the effects of observational biases on measures of the cluster distribution function and on cosmological constraints derived from X-ray cluster populations. I also demonstrate the indispensability of the multi-variate approach in measuring the evolution of X-ray galaxy clusters; without it, we find that the combination of scatter, intrinsic correlation and irrevocable survey flux limits substantially confuses any measure of redshift evolution. Next, I construct the Millennium Gas Simulation-Virtual Sky Survey (MGSVSS), a multi-wavelength mock sky derived from an N-body gas-dynamic simulation. The MGSVSS contains both sub-mm and optical wavelength sky signals to redshift, z = 1., in a 5 x 5deg2 field of view, with O (103) halos, O (104) optically selected clusters, and O (102) clusters selected via the Sunyaev-Zel'dovich (SZ) signature. The SZ sky also includes a minimal level of sky and instrumental noise, which nearly mimics that of

  6. Multi-wavelength aerosol light absorption measurements in the Amazon rainforest

    NASA Astrophysics Data System (ADS)

    Saturno, Jorge; Chi, Xuguang; Pöhlker, Christopher; Morán, Daniel; Ditas, Florian; Massabò, Dario; Prati, Paolo; Rizzo, Luciana; Artaxo, Paulo; Andreae, Meinrat

    2015-04-01

    The most important light-absorbing aerosol is black carbon (BC), which is emitted by incomplete combustion of fossil fuels and biomass. BC is considered the second anthropogenic contributor to global warming. Beyond BC, other aerosols like some organics, dust, and primary biological aerosol particles are able to absorb radiation. In contrast to BC, the light absorption coefficient of these aerosols is wavelength dependent. Therefore, multi-wavelength measurements become important in environments where BC is not the predominant light-absorbing aerosol like in the Amazon. The Amazon Tall Tower Observatory (ATTO) site is located in the remote Amazon rainforest, one of the most pristine continental sites in the world during the wet season. In the dry season, winds coming from the southern hemisphere are loaded with biomass burning aerosol particles originated by farming-related deforestation. BC and aerosol number concentration data from the last two years indicate this is the most polluted period. Two different techniques have been implemented to measure the light absorption at different wavelengths; one of them is the 7-wavelengths Aethalometer, model AE30, an instrument that measures the light attenuation on a filter substrate and requires multiple scattering and filter-loading corrections to retrieve the light absorption coefficient. The other method is an offline technique, the Multi-Wavelength Absorbance Analysis (MWAA), which is able to measure reflectance and absorbance by aerosols collected on a filter and, by means of a radiative model, can retrieve the light absorption coefficient. Filters collected during May-September 2014, comprehending wet-to-dry transition and most of the dry season, were analyzed. The results indicate that the Absorption Ångström Exponent (AAE), a parameter that is directly proportional to the wavelength dependence of the aerosol light absorption, is close to 1.0 during the transition period and slightly decreases in the beginning of

  7. MULTI-WAVELENGTH RADIO CONTINUUM EMISSION STUDIES OF DUST-FREE RED GIANTS

    SciTech Connect

    O'Gorman, Eamon; Harper, Graham M.; Brown, Alexander; Drake, Stephen; Richards, Anita M. S.

    2013-10-01

    Multi-wavelength centimeter continuum observations of non-dusty, non-pulsating K spectral-type red giants directly sample their chromospheres and wind acceleration zones. Such stars are feeble emitters at these wavelengths, however, and previous observations have provided only a small number of modest signal-to-noise measurements slowly accumulated over three decades. We present multi-wavelength Karl G. Jansky Very Large Array thermal continuum observations of the wind acceleration zones of two dust-free red giants, Arcturus (α Boo: K2 III) and Aldebaran (α Tau: K5 III). Importantly, most of our observations of each star were carried out over just a few days, so that we obtained a snapshot of the different stellar atmospheric layers sampled at different wavelengths, independent of any long-term variability. We report the first detections at several wavelengths for each star including a detection at 10 cm (3.0 GHz: S band) for both stars and a 20 cm (1.5 GHz: L band) detection for α Boo. This is the first time single (non-binary) luminosity class III red giants have been detected at these continuum wavelengths. Our long-wavelength data sample the outer layers of α Boo's atmosphere where its wind velocity is approaching (or possibly has reached) its terminal value and the ionization balance is becoming frozen-in. For α Tau, however, our long-wavelength data are still sampling its inner atmosphere, where the wind is still accelerating probably due to its lower mass-loss rate. We compare our data with published semi-empirical models based on ultraviolet data, and the marked deviations highlight the need for new atmospheric models to be developed. Spectral indices are used to discuss the possible properties of the stellar atmospheres, and we find evidence for a rapidly cooling wind in the case of α Boo. Finally, we develop a simple analytical wind model for α Boo based on our new long-wavelength flux measurements.

  8. Multi-wavelength Radio Continuum Emission Studies of Dust-free Red Giants

    NASA Technical Reports Server (NTRS)

    O'Gorman, Eamon; Harper, Graham M.; Brown, Alexander; Dranke, Stephen; Richards, Anita M. S.

    2013-01-01

    Multi-wavelength centimeter continuum observations of non-dusty, non-pulsating K spectral-type red giants directly sample their chromospheres and wind acceleration zones. Such stars are feeble emitters at these wavelengths, however, and previous observations have provided only a small number of modest signal-to-noise measurements slowly accumulated over three decades. We present multi-wavelength Karl G. Jansky Very Large Array thermal continuum observations of the wind acceleration zones of two dust-free red giants, Arcturus (alpha Boo: K2 III) and Aldebaran (alpha Tau: K5 III). Importantly, most of our observations of each star were carried out over just a few days, so that we obtained a snapshot of the different stellar atmospheric layers sampled at different wavelengths, independent of any long-term variability. We report the first detections at several wavelengths for each star including a detection at 10 cm (3.0 GHz: S band) for both stars and a 20 cm (1.5 GHz: L band) detection for alpha Boo. This is the first time single (non-binary) luminosity class III red giants have been detected at these continuum wavelengths. Our long-wavelength data sample the outer layers of alpha Boo's atmosphere where its wind velocity is approaching (or possibly has reached) its terminal value and the ionization balance is becoming frozen-in. For alpha Tau, however, our long-wavelength data are still sampling its inner atmosphere, where the wind is still accelerating probably due to its lower mass-loss rate. We compare our data with published semi-empirical models based on ultraviolet data, and the marked deviations highlight the need for new atmospheric models to be developed. Spectral indices are used to discuss the possible properties of the stellar atmospheres, and we find evidence for a rapidly cooling wind in the case of alpha Boo. Finally, we develop a simple analytical wind model for alpha Boo based on our new long-wavelength flux measurements.

  9. CMOS Imaging Detectors as X-ray Detectors for Synchrotron Radiation Experiments

    SciTech Connect

    Yagi, Naoto; Uesugi, Kentaro; Inoue, Katsuaki

    2004-05-12

    CMOS imagers are matrix-addressed photodiode arrays, which have been utilized in devices such as commercially available digital cameras. The pixel size of CMOS imagers is usually larger than that of CCD and smaller than that of TFT, giving them a unique position. Although CMOS x-ray imaging devices have already become commercially available, they have not been used as an x-ray area detector in synchrotron radiation experiments. We tested performance of a CMOS detector from Rad-icon (Shad-o-Box1024) in medical imaging, small-angle scattering, and protein crystallography experiments. It has pixels of 0.048 mm square, read-out time of 0.45 sec, 12-bit ADC, and requires a frame grabber for image acquisition. The detection area is 5-cm square. It uses a Kodak Min-R scintillator screen as a phosphor. The sensitivity to x-rays with an energy less than 15 keV was low because of the thick window materials. Since the readout noise is high, the dynamic range is limited to 2000. The biggest advantages of this detector are cost-effectiveness (about 10,000 US dollars) and compactness (thickness < 3 cm, weight < 2 kg)

  10. Autoradiography Imaging in Targeted Alpha Therapy with Timepix Detector

    PubMed Central

    AL Darwish, Ruqaya; Staudacher, Alexander Hugo; Bezak, Eva; Brown, Michael Paul

    2015-01-01

    There is a lack of data related to activity uptake and particle track distribution in targeted alpha therapy. These data are required to estimate the absorbed dose on a cellular level as alpha particles have a limited range and traverse only a few cells. Tracking of individual alpha particles is possible using the Timepix semiconductor radiation detector. We investigated the feasibility of imaging alpha particle emissions in tumour sections from mice treated with Thorium-227 (using APOMAB), with and without prior chemotherapy and Timepix detector. Additionally, the sensitivity of the Timepix detector to monitor variations in tumour uptake based on the necrotic tissue volume was also studied. Compartmental analysis model was used, based on the obtained imaging data, to assess the Th-227 uptake. Results show that alpha particle, photon, electron, and muon tracks were detected and resolved by Timepix detector. The current study demonstrated that individual alpha particle emissions, resulting from targeted alpha therapy, can be visualised and quantified using Timepix detector. Furthermore, the variations in the uptake based on the tumour necrotic volume have been observed with four times higher uptake for tumours pretreated with chemotherapy than for those without chemotherapy. PMID:25688285

  11. Two-Sided Coded Aperture Imaging Without a Detector Plane

    SciTech Connect

    Ziock, Klaus-Peter; Cunningham, Mark F; Fabris, Lorenzo

    2009-01-01

    We introduce a novel design for a two-sided, coded-aperture, gamma-ray imager suitable for use in stand off detection of orphan radioactive sources. The design is an extension of an active-mask imager that would have three active planes of detector material, a central plane acting as the detector for two (active) coded-aperture mask planes, one on either side of the detector plane. In the new design the central plane is removed and the mask on the left (right) serves as the detector plane for the mask on the right (left). This design reduces the size, mass, complexity, and cost of the overall instrument. In addition, if one has fully position-sensitive detectors, then one can use the two planes as a classic Compton camera. This enhances the instrument's sensitivity at higher energies where the coded-aperture efficiency is decreased by mask penetration. A plausible design for the system is found and explored with Monte Carlo simulations.

  12. Autoradiography imaging in targeted alpha therapy with Timepix detector.

    PubMed

    A L Darwish, Ruqaya; Staudacher, Alexander Hugo; Bezak, Eva; Brown, Michael Paul

    2015-01-01

    There is a lack of data related to activity uptake and particle track distribution in targeted alpha therapy. These data are required to estimate the absorbed dose on a cellular level as alpha particles have a limited range and traverse only a few cells. Tracking of individual alpha particles is possible using the Timepix semiconductor radiation detector. We investigated the feasibility of imaging alpha particle emissions in tumour sections from mice treated with Thorium-227 (using APOMAB), with and without prior chemotherapy and Timepix detector. Additionally, the sensitivity of the Timepix detector to monitor variations in tumour uptake based on the necrotic tissue volume was also studied. Compartmental analysis model was used, based on the obtained imaging data, to assess the Th-227 uptake. Results show that alpha particle, photon, electron, and muon tracks were detected and resolved by Timepix detector. The current study demonstrated that individual alpha particle emissions, resulting from targeted alpha therapy, can be visualised and quantified using Timepix detector. Furthermore, the variations in the uptake based on the tumour necrotic volume have been observed with four times higher uptake for tumours pretreated with chemotherapy than for those without chemotherapy. PMID:25688285

  13. Energy dispersive photon counting detectors for breast imaging

    NASA Astrophysics Data System (ADS)

    Barber, William C.; Wessel, Jan C.; Malakhov, Nail; Wawrzyniak, Gregor; Hartsough, Neal E.; Gandhi, Thulasidharan; Nygard, Einar; Iwanczyk, Jan S.

    2013-09-01

    We report on our efforts toward the development of silicon (Si) strip detectors for energy-resolved clinical breast imaging. Typically, x-ray integrating detectors based on scintillating cesium iodide CsI(Tl) or amorphous selenium (a- Se) are used in most commercial systems. Recently, mammography instrumentation has been introduced based on photon counting silicon Si strip detectors. Mammography requires high flux from the x-ray generator, therefore, in order to achieve energy resolved single photon counting, a high output count rate (OCR) for the detector must be achieved at the required spatial resolution and across the required dynamic range for the application. The required performance in terms of the OCR, spatial resolution, and dynamic range must be obtained with sufficient field of view (FOV) for the application thus requiring the tiling of pixel arrays and scanning techniques. Room temperature semiconductors, operating as direct conversion x-ray sensors, can provide the required speed when connected to application specific integrated circuits (ASICs) operating at fast peaking times with multiple fixed thresholds per pixel, provided that the sensors are designed for rapid signal formation across the x-ray energy ranges of the application at the required energy and spatial resolutions. We present our methods and results from the optimization of prototype detectors based on Si strip structures. We describe the detector optimization and the development of ASIC readout electronics that provide the required spatial resolution, low noise, high count rate capabilities and minimal power consumption.

  14. Tunable and switchable multi-wavelength fiber laser based on semiconductor optical amplifier and twin-core photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Kim, Bongkyun; Han, Jihee; Chung, Youngjoo

    2012-02-01

    Multi-wavelength fiber lasers have attracted a lot of interest, recently, because of their potential applications in wavelength-division-multiplexing (WDM) systems, optical fiber sensing, and fiber-optics instruments, due to their numerous advantages such as multiple wavelength operation, low cost, and compatibility with the fiber optic systems. Semiconductor optical amplifier (SOA)-based multi-wavelength fiber lasers exhibit stable operation because of the SOA has the property of primarily inhomogeneous broadening and thus can support simultaneous oscillation of multiple lasing wavelengths. In this letter, we propose and experimentally demonstrate a switchable multi-wavelength fiber laser employing a semiconductor optical amplifier and twin-core photonic crystal fiber (TC-PCF) based in-line interferometer comb filter. The fabricated two cores are not symmetric due to the associated fiber fabrication process such as nonuniform heat gradient in furnace and asymmetric microstructure expansion during the gas pressurization which results in different silica strut thickness and core size. The induced asymmetry between two cores considerably alters the linear power transfer, by seriously reducing it. These nominal twin cores form effective two optical paths and associated effective refractive index difference. The in-fiber comb filter is effectively constructed by splicing a section of TC-PCF between two single mode fibers (SMFs). The proposed laser can be designed to operate in stable multi-wavelength lasing states by adjusting the states of the polarization controller (PC). The lasing modes are switched by varying the state of PC and the change is reversible. In addition, we demonstrate a tunable multi-wavelength fiber laser operation by applying temperature changes to TC-PCF in the multi-channel filter.

  15. Multi-wavelength diagnostics and modelling of the emission during a B6.4 flare of August 20, 2005

    NASA Astrophysics Data System (ADS)

    Awasthi, Arun Kumar; Berlicki, Arkadiusz; Rudawy, Powel; Heinzel, Petr

    2015-08-01

    We study the temporal, spatial and spectral evolution of multi-wavelength emission observed during a B6.4 flare occurred on August 20, 2005 with the motivation to outline the thermal and non-thermal processes during the precursor and gradual phase of the flare. Precursor phase is designated as the gradual enhancement of soft X-ray emission prior to onset of the impulsive phase. Observations from several space and ground based observatories viz. RHESSI, TRACE, GONG, SoHO/EIT and NoRP are included in this study. Temporal evolution of X-ray emission does not show the presence of hard X-rays (>12 keV) emission during the precursor phase of the flare. We synthesized X-ray images in 6-12 keV from RHESSI observations, which show several discrete sources during the precursor phase. Following to this, one of these sources pronounced during the main phase of the flare. We carry out in-depth analysis of chromospheric response in various phases of the flare employing high temporal cadence images of the Sun in Hα line centre as well as wings obtained from the Multi-channel Subtractive Double Pass Spectrograph (MSDP) at the Bialkow Observatory of the University of Wroclaw, Poland. Our analysis of Hα images during the main phase of the flare suggests localized emission in the form of kernels. On the contrary, we note extended and diffused source morphology of emitting region during the precursor phase of the flare. We also study various kinematic properties of different structures visible in the Hα images in the line centre as well as wings. In addition, the correlation of the relative timing of X-ray and Hα emission profile is performed to estimate the delay in the chromospheric response during different phases of flare. Further, we employ thermal plasma parameters estimated during the precursor and gradual phase to model the associated Hα emission. For the modeling we employ NLTE numerical codes modified for flare conditions. The modeled and observed flare emission

  16. Quantitative SPECT brain imaging: Effects of attenuation and detector response

    SciTech Connect

    Gilland, D.R.; Jaszczak, R.J.; Bowsher, J.E.; Turkington, T.G.; Liang, Z.; Greer, K.L.; Coleman, R.E. . Dept. of Radiology)

    1993-06-01

    Two physical factors that substantially degrade quantitative accuracy in SPECT imaging of the brain are attenuation and detector response. In addition to the physical factors, random noise in the reconstructed image can greatly affect the quantitative measurement. The purpose of this work was to implement two reconstruction methods that compensate for attenuation and detector response, a 3D maximum likelihood-EM method (ML) and a filtered backprojection method (FB) with Metz filter and Chang attenuation compensation, and compare the methods in terms of quantitative accuracy and image noise. The methods were tested on simulated data of the 3D Hoffman brain phantom. The simulation incorporated attenuation and distance-dependent detector response. Bias and standard deviation of reconstructed voxel intensities were measured in the gray and white matter regions. The results with ML showed that in both the gray and white matter regions as the number of iterations increased, bias decreased and standard deviation increased. Similar results were observed with FB as the Metz filter power increased. In both regions, ML had smaller standard deviation than FB for a given bias. Reconstruction times for the ML method have been greatly reduced through efficient coding, limited source support, and by computing attenuation factors only along rays perpendicular to the detector.

  17. DUNBID, the Delft University neutron backscattering imaging detector.

    PubMed

    Bom, V R; van Eijk, C W E; Ali, M A

    2005-01-01

    In the search for low-metallic land mines, the neutron backscattering technique may be applied if the soil is sufficiently dry. An advantage of this method is the speed of detection: the scanning speed may be made comparable to that of a metal detector. A two-dimensional position sensitive detector is tested to obtain an image of the back scattered thermal neutron radiation. Results of experiments using a radionuclide neutron source are presented. The on-mine to no-mine signal ratio can be improved by the application of a window on the neutron time-of-flight. Results using a pulsed neutron generator are also presented. PMID:16029950

  18. Development of Superconducting Tunnel Junction as an Imaging Radiation Detector

    NASA Astrophysics Data System (ADS)

    Yamasaki, N. Y.; Rokutanda, E.; Kikuchi, K.; Kushino, A.; Ohashi, T.; Kurakado, M.

    Superconducting tunnel junctions (STJs) as X-ray detectors have been developed mainly aiming at high resolution spectrometers. We archived an energy resolution of 106 eV at 5.9 keV (FWHM) using an STJ developed at Nippon Steel Corporation with a cooled (~ 100K) FET. Furthermore, series-connected STJs as an imaging radiation detector are developed. Both the pulse hight and the rise time of signals from 241Am α-particles irradiated on a series-connected STJ give a good position sensitivity, indicating the intrinsic position resolution less than 0.5 mm

  19. Multi-wavelength modeling of globular clusters–the millisecond pulsar scenario

    SciTech Connect

    Kopp, A.; Venter, C.; Büsching, I.; De Jager, O. C.

    2013-12-20

    The potentially large number of millisecond pulsars (MSPs) in globular cluster (GC) cores makes these parent objects ideal laboratories for studying the collective properties of an ensemble of MSPs. Such a population is expected to radiate several spectral components in the radio through γ-ray waveband. First, pulsed emission is expected via curvature and synchrotron radiation (CR and SR) and possibly even via inverse Compton (IC) scattering inside the pulsar magnetospheres. Second, unpulsed emission should transpire through the continuous injection of relativistic leptons by the MSPs into the ambient region, which in turn produce SR and IC emission when they encounter the cluster magnetic field, as well as several background photon components. In this paper we continue to develop the MSP scenario for explaining the multi-wavelength properties of GCs by considering the entire modeling chain, including the full transport equation, refined emissivities of stellar and Galactic background photons, integration of the flux along the line of sight, and comparison with observations. As an illustration, we apply the model to Terzan 5, where we can reasonably fit both the (line-of-sight-integrated) X-ray surface flux and spectral energy density data, using the first to constrain the leptonic diffusion coefficient within the GC. We lastly discuss possible future extensions to and applications of this maturing model.

  20. A new multi-wavelength model-based method for determination of enzyme kinetic parameters.

    PubMed

    Sorouraddin, Mohammad-Hossein; Amini, Kaveh; Naseri, Abdolhossein; Vallipour, Javad; Hanaee, Jalal; Rashidi, Mohammad-Reza

    2010-09-01

    Lineweaver-Burk plot analysis is the most widely used method to determine enzyme kinetic parameters. In the spectrophotometric determination of enzyme activity using the Lineweaver-Burk plot, it is necessary to find a wavelength at which only the substrate or the product has absorbance without any spectroscopic interference of the other reaction components. Moreover, in this method, different initial concentrations of the substrate should be used to obtain the initial velocities required for Lineweaver-Burk plot analysis. In the present work, a multi-wavelength model-based method has been developed and validated to determine Michaelis-Menten constants for some enzyme reactions. In this method, a selective wavelength region and several experiments with different initial concentrations of the substrate are not required. The absorbance data of the kinetic assays are fitted by non-linear regression coupled to the numeric integration of the related differential equation. To indicate the applicability of the proposed method, the Michaelis-Menten constants for the oxidation of phenanthridine, 6-deoxypenciclovir and xanthine by molybdenum hydroxylases were determined using only a single initial concentration of the substrate, regardless of any spectral overlap. PMID:20826949

  1. Multi-wavelength injection seeded mid-infrared optical parametric oscillator for DIAL

    SciTech Connect

    Webb, M.S.; Stanion, K.B.; Deane, D.J.

    1996-01-27

    We have constructed and fielded a multi-wavelength injection seeded mid-IR OPO source for DIAL. This OPO system was built for ground based remote sensing measurements of species with both broad (300 cm{sup -1}) and narrow absorption bandwidths (0.07 cm{sup -1} FWHM). The OPO utilizes a single frequency tunable diode laser for the injection seeded signal wavelength in the region from 6400 to 6700 cm{sup -1} and an angle phase-matched 5 cm LiNbO3 crystal to provide large tuning excursions on a slow time scale. The pump was a diode pumped Nd:YAG MOPA (9398 cm{sup -1}) running at 180 Hz. This pump source was repeatedly injection seeded with a different wavelength on each of film sequential shots forming a set of three pulses having wavelength separations on the order of 0.4 cm{sup -1} at a three color set repetition rate of 60 Hz. This combination of OPO signal and pump source produced a set of three time staggered idler wavelengths separated by 0.4 cm{sup -1} with the center wavelength tunable from 2700 to 3000 cm{sup -1}. This OPO system was used in field test experiments to detect the release of chemicals from a standoff distance of 3.3 Km. We present key OPO design criteria, performance data, and numerical simulations that agree with our observations of pump induced spectral impurities in the OPO output.

  2. Temporal characterization of a multi-wavelength Brillouin–erbium fiber laser

    NASA Astrophysics Data System (ADS)

    Lambin Iezzi, Victor; Büttner, Thomas F. S.; Tehranchi, Amirhossein; Loranger, Sébastien; Kabakova, Irina V.; Eggleton, Benjamin J.; Kashyap, Raman

    2016-05-01

    This paper provides the first detailed temporal characterization of a multi-wavelength-Brillouin–erbium fiber laser (MWBEFL) by measuring the optical intensity of the individual frequency channels with high temporal resolution. It is found that the power in each channel is highly unstable due to the excitation of several cavity modes for typical conditions of operation. Also provided is the real-time measurements of the MWBEFL output power for two configurations that were previously reported to emit phase-locked picosecond pulse trains, concluded from their autocorrelation measurements. Real-time measurements reveal a high degree of instability without the formation of a stable pulse train. Finally, we model the MWBEFL using coupled wave equations describing the evolution of the Brillouin pump, Stokes and acoustic waves in the presence of stimulated Brillouin scattering, and the optical Kerr effect. A good qualitative consistency between the simulation and experimental results is evident, in which the interference signal at the output shows strong instability as well as the chaotic behavior due to the dynamics of participating pump and Stokes waves.

  3. Multi-wavelength optical determination of black and brown carbon in atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Massabò, D.; Caponi, L.; Bernardoni, V.; Bove, M. C.; Brotto, P.; Calzolai, G.; Cassola, F.; Chiari, M.; Fedi, M. E.; Fermo, P.; Giannoni, M.; Lucarelli, F.; Nava, S.; Piazzalunga, A.; Valli, G.; Vecchi, R.; Prati, P.

    2015-05-01

    In this paper, a new way to apportion the absorption coefficient (babs) of carbonaceous atmospheric aerosols starting from a multi-wavelength optical analysis is shown. This methodology can disentangle and quantify the contribution to total absorption of equivalent black carbon (EBC) emitted by wood burning (EBCWB) and fossil fuel (EBCFF) as well as brown carbon (BrC) due to incomplete combustion. The method uses the information gathered at five different wavelengths in a renewed and upgraded version of the approach usually referred to as Aethalometer model. Moreover, we present the results of an apportionment study of carbonaceous aerosol sources performed in a rural area and in a coastal city, both located in the North-West of Italy. Results obtained by the proposed approach are validated against independent measurements of levoglucosan and radiocarbon. At the rural site the EBCWB and EBCFF relative contributions are about 40% and 60% in winter and 15% and 85% in summer, respectively. At the coastal urban site, EBCWB and EBCFF are about 15% and 85% during fall. The OC contribution to the wood burning source at the rural site results approximately 50% in winter and 10% in summer and about 15% at the coastal urban site in fall. The new methodology also provides a direct measurement of the absorption Ångström exponent of BrC (αBrC) which resulted αBrC = 3.95 ± 0.20.

  4. Cosmic rays from multi-wavelength observations of the Galactic diffuse emission

    NASA Astrophysics Data System (ADS)

    Orlando, Elena

    2016-05-01

    Cosmic rays (CRs) generate diffuse emission while interacting with the Galactic magnetic field (B-field), the interstellar gas and the radiation field. This diffuse emission extends from radio, microwaves, through X-rays, to high-energy gamma rays. Diffuse emission has considerably increased the interest of the astrophysical community due to recent detailed observations by Planck, Fermi-LAT, and by very-high energy Cherenkov telescopes. Observations of this diffuse emission and comparison with detailed predictions are used to gain information on the properties of CRs, such as their density, spectra, distribution and propagation in the Galaxy. Unfortunately disentangling and characterizing this diffuse emission strongly depends on uncertainties in the knowledge of unresolved sources, gas, radiation fields, and B-fields, other than CRs throughout the Galaxy. We discuss here the diffuse emission produced by CRs and its uncertainties, and the comparison of this predicted emission with recent multi-wavelength observations. We show insights on CR spectra and intensities. Then we address the importance for forthcoming telescopes, especially for the Square Kilometre Array telescope (SKA) and the Cherencov Telescope Array (CTA), and for missions at MeV.

  5. [Multi-wavelength spectral aerosol scale height in inshore in contrast with that in inland].

    PubMed

    Han, Yong; Rao, Rui-Zhong; Wang, Ying-Jian

    2009-01-01

    In the present paper, based on the exponential attenuation of atmospheric aerosol concentration with height, so using continuous spectrum sun-photometer, forward scatter visibility sensor and hygrothermograph, the authors measured the atmosphere column optical characteristic and plane spectral extinction coefficient on earth on the base of two experiments at some edge of ocean at the same time, respectively, set up the calculative method of multi-wavelength spectral aerosol scale height. Firstly, the authors obtained atmospheric horizontal extinction coefficient with forward scattering visibility sensor, which subtracted molecular extinction coefficient, and could get aerosol extinction coefficient near ground; Then, selecting sea salt model, using OPAC software, the authors also could calculate the aerosol extinction coefficient under different humidity (0%, 50%, 70%, 80%, 90%, 95%, 98% and 99%) and different wavelength (400, 450, 500, 550, 600, 650, 700 and 750 nm), the aerosol extinction coefficient was detected by visibility sensor, using interpolation method, respectively; Finally, using the data of atmospheric columniation optical thickness detected by continuous spectral sun-photometer and subtracted molecular optical thickness corresponding wavelengths were accounted out by Modtran 4. 0. The authors obtained the characteristic of spectral aerosol scale height of visible light (wavelength is 400, 440, 532, 550 and 690 nm): with wavelength increments, and spectral aerosol scale height was found to decline neither in inland nor in inshore in China; Spectral aerosol scale height in winter is higher than in summer in southeast inshore; but spectral aerosol scale height in winter is smaller in summer than in inland. PMID:19385200

  6. Non-invasive in vivo monitoring of circulating amphotericin b using multi-wavelength photoplethysmography

    NASA Astrophysics Data System (ADS)

    Adhikari, Pratik; Eklund, Wakako; O'Neal, D. P.

    2015-03-01

    A novel multi-wavelength photoplethysmograph (PPG), previously utilized to quantify optically absorptive circulating gold nanoparticles, has demonstrated the potential to enhance therapeutic treatment predictability as pharmacokinetic metrics are provided throughout the intravenous delivery and clearance phase of amphotericin b (injected in the lipid form Abelcet®) in real-time. This report demonstrates how the PPG could be used to assess the real-time bioavailability of intravenously delivered optically-absorbing therapeutic agents. The drug currently under investigation is antifungal amphotericin b (absorption peak ~355 nm). We describe how the algorithm has been adapted to quantify the concentration of amphotericin b in the pulsatile, circulating blood based on its extinction at three wavelengths (355, 660 and 940 nm) corresponding to the peaks of amphotericin b and wavelengths for oxygen saturation measurements, respectively. We show an example of the system collecting data representing the baseline, injection, and the clearance phases. The PPG device showed a measurement range of concentrations between 0.0987 mg/mL to 0.025mg/ml in blood. An examination of the data obtained suggests that the system is well suited to sense the concentration of amphotericin b at a therapeutic dose (≍5 mg/kg/day).

  7. MULTI-WAVELENGTH OBSERVATIONS OF COMET C/2011 L4 (PAN-STARRS)

    SciTech Connect

    Yang, Bin; Keane, Jacqueline; Meech, Karen; Owen, Tobias; Wainscoat, Richard

    2014-04-01

    The dynamically new comet C/2011 L4 (Pan-STARRS) is one of the brightest comets observed since the great comet C/1995 O1 (Hale-Bopp). Here, we present our multi-wavelength observations of C/2011 L4 during its in-bound passage to the inner solar system. A strong absorption band of water ice at 2.0 μm was detected in the near-infrared spectra, obtained with the 8 m Gemini-North and 3 m Infrared Telescope Facility Telescopes. The companion 1.5 μm band of water ice, however, was not observed. Spectral modeling shows that the absence of the 1.5 μm feature can be explained by the presence of sub-micron-sized fine ice grains. No gas lines (i.e., CN, HCN, or CO) were observed pre-perihelion in either the optical or the submillimeter. We derived 3σ upper limits for the CN and CO production rates. The comet exhibited a very strong continuum in the optical and its slope seemed to become redder as the comet approached the Sun. Our observations suggest that C/2011 L4 is an unusually dust-rich comet with a dust-to-gas mass ratio >4.

  8. A multi-wavelength study on gamma-ray bursts and their afterglows

    NASA Astrophysics Data System (ADS)

    Zhang, Binbin

    2011-08-01

    During the prompt emission and afterglow phases, GRBs (Gamma-Ray Bursts) release their huge amount of energy not limited in gamma-ray, but in a wide range of muti-wavelengths, from radio band to GeV gamma-rays. Thanks to the recent missions of Swift and Fermi, I was able to use their multi-wavelength observation data of GRBs and study their physical natures. I have processed all the Swift BAT/XRT and Fermi GBM/LAT GRB observation data. Based on the Swift data, I have studied the following comprehensive topics: (1) high-latitude "curvature effect" of early X-ray tails of GRBs Swift XRT afterglow (2) diverse physical origins of shallow decay phase of Swift XRT afterglow. (3) Jet break (in-)consistency in both X-Ray and Optical observations. Based on the Fermi observation data, I focused on the 17 GRBs with Fermi/LAT high-energy emission and found there are three elemental spectral components, namely, a classical "Band" function component, a quasi-thermal component and an extra non-thermal power law component extending to high energies. The detailed behaviors of these three components are extensively studied and their physical origins and corresponding jet properties and emission mechanisms are also discussed.

  9. The ECLAIRs micro-satellite mission for gamma-ray burst multi-wavelength observations

    NASA Astrophysics Data System (ADS)

    Schanne, S.; Atteia, J.-L.; Barret, D.; Basa, S.; Boer, M.; Casse, F.; Cordier, B.; Daigne, F.; Klotz, A.; Limousin, O.; Manchanda, R.; Mandrou, P.; Mereghetti, S.; Mochkovitch, R.; Paltani, S.; Paul, J.; Petitjean, P.; Pons, R.; Ricker, G.; Skinner, G.

    2006-11-01

    Gamma-ray bursts (GRB)—at least those with a duration longer than a few seconds—are the most energetic events in the Universe and occur at cosmological distances. The ECLAIRs micro-satellite, to be launched in 2009, will provide multi-wavelength observations of GRB, to study their astrophysics and to use them as cosmological probes. Furthermore, in 2009 ECLAIRs is expected to be the only space-borne instrument capable of providing a GRB trigger in near real-time with sufficient localization accuracy for GRB follow-up observations with the powerful ground-based spectroscopic telescopes available by then. A “Phase A study” of the ECLAIRs project has recently been launched by the French Space Agency CNES, aiming at a detailed mission design and selection for flight in 2006. The ECLAIRs mission is based on a CNES micro-satellite of the “Myriade” family and dedicated ground-based optical telescopes. The satellite payload combines a 2 sr field-of-view coded aperture mask gamma-camera using 6400 CdTe pixels for GRB detection and localization with 10 arcmin precision in the 4 50 keV energy band, together with a soft X-ray camera for onboard position refinement to 1 arcmin. The ground-based optical robotic telescopes will detect the GRB prompt/early afterglow emission and localize the event to arcsec accuracy, for spectroscopic follow-up observations.

  10. THE STABILITY OF LOW SURFACE BRIGHTNESS DISKS BASED ON MULTI-WAVELENGTH MODELING

    SciTech Connect

    MacLachlan, J. M.; Wood, K.; Matthews, L. D.; Gallagher, J. S.

    2011-11-01

    To investigate the structure and composition of the dusty interstellar medium (ISM) of low surface brightness (LSB) disk galaxies, we have used multi-wavelength photometry to construct spectral energy distributions for three low-mass, edge-on LSB galaxies (V{sub rot} = 88-105 km s{sup -1}). We use Monte Carlo radiation transfer codes that include the effects of transiently heated small grains and polycyclic aromatic hydrocarbon molecules to model and interpret the data. We find that, unlike the high surface brightness galaxies previously modeled, the dust disks appear to have scale heights equal to or exceeding their stellar scale heights. This result supports the findings of previous studies that low-mass disk galaxies have dust scale heights comparable to their stellar scale heights and suggests that the cold ISM of low-mass, LSB disk galaxies may be stable against fragmentation and gravitational collapse. This may help to explain the lack of observed dust lanes in edge-on LSB galaxies and their low current star formation rates. Dust masses are found in the range (1.16-2.38) x 10{sup 6} M{sub sun}, corresponding to face-on (edge-on), V-band, optical depths 0.034 {approx}< {tau}{sub face} {approx}< 0.106 (0.69 {approx}< {tau}{sub eq} {approx}< 1.99).