Science.gov

Sample records for illumination based detector

  1. Junction-side illuminated silicon detector arrays

    DOEpatents

    Iwanczyk, Jan S.; Patt, Bradley E.; Tull, Carolyn

    2004-03-30

    A junction-side illuminated detector array of pixelated detectors is constructed on a silicon wafer. A junction contact on the front-side may cover the whole detector array, and may be used as an entrance window for light, x-ray, gamma ray and/or other particles. The back-side has an array of individual ohmic contact pixels. Each of the ohmic contact pixels on the back-side may be surrounded by a grid or a ring of junction separation implants. Effective pixel size may be changed by separately biasing different sections of the grid. A scintillator may be coupled directly to the entrance window while readout electronics may be coupled directly to the ohmic contact pixels. The detector array may be used as a radiation hardened detector for high-energy physics research or as avalanche imaging arrays.

  2. Use of Sub-bandgap Illumination to Improve Radiation Detector Resolution of CdZnTe

    NASA Astrophysics Data System (ADS)

    Duff, Martine C.; Washington, Aaron L.; Teague, Lucile C.; Wright, Jonathan S.; Burger, Arnold; Groza, Michael; Buliga, Vladimir

    2015-09-01

    The performance of Cd1- x Zn x Te (CZT) materials for room-temperature gamma/x-ray radiation detection continues to improve in terms of material quality and detector design. In our prior publications, we investigated the use of multiple wavelengths of light (in the visible and infrared) to target charge carriers at various trap energies and physical positions throughout crystals. Light exposure significantly alters the charge mobility and improves carrier collection at the anode contact. This study presents an investigation of material performance as a radiation detector during such illumination. The decrease in charge trapping and increase in charge collection due to a higher probability of free electron release from traps contributed to an increase in the resolution-based performance of the detector through controlled illumination. We investigated the performance improvement of CZT crystals with previously known levels of intrinsic defects and secondary phases, at various voltages, light-emitting diode (LED) light wavelengths, and shaping times. Although our setup was clearly not optimized for radiation detector performance, it demonstrated substantial resolution improvements (based on full-width at half-maximum using 662-keV gamma rays from 137Cs upon illumination with 950-nm light) of 16% to 38% in comparison with unilluminated CZT under similar conditions. This manuscript includes discussion of the electrooptic behavior and its effect on performance. Additional testing and fabrication of a detector that incorporates such LED light optimization could lead to improved performance with existing detector-grade materials.

  3. Broadband illumination of superconducting pair breaking photon detectors

    NASA Astrophysics Data System (ADS)

    Guruswamy, T.; Goldie, D. J.; Withington, S.

    2016-04-01

    Understanding the detailed behaviour of superconducting pair breaking photon detectors such as Kinetic Inductance Detectors (KIDs) requires knowledge of the nonequilibrium quasiparticle energy distributions. We have previously calculated the steady state distributions resulting from uniform absorption of monochromatic sub gap and above gap frequency radiation by thin films. In this work, we use the same methods to calculate the effect of illumination by broadband sources, such as thermal radiation from astrophysical phenomena or from the readout system. Absorption of photons at multiple above gap frequencies is shown to leave unchanged the structure of the quasiparticle energy distribution close to the superconducting gap. Hence for typical absorbed powers, we find the effects of absorption of broadband pair breaking radiation can simply be considered as the sum of the effects of absorption of many monochromatic sources. Distribution averaged quantities, like quasiparticle generation efficiency η, match exactly a weighted average over the bandwidth of the source of calculations assuming a monochromatic source. For sub gap frequencies, however, distributing the absorbed power across multiple frequencies does change the low energy quasiparticle distribution. For moderate and high absorbed powers, this results in a significantly larger η-a higher number of excess quasiparticles for a broadband source compared to a monochromatic source of equal total absorbed power. Typically in KIDs the microwave power absorbed has a very narrow bandwidth, but in devices with broad resonance characteristics (low quality factors), this increase in η may be measurable.

  4. MWIR superlattice detectors integrated with substrate side-illuminated plasmonic coupler

    NASA Astrophysics Data System (ADS)

    Zamiri, M.; Plis, E.; Kim, J. O.; Lee, S. C.; Neumann, A.; Myers, S.; Smith, E. P.; Itsuno, A. M.; Wehner, J. G. A.; Johnson, S. M.; Brueck, S. R. J.; Krishna, S.

    2014-06-01

    Detectivity of mid-wave infrared (MWIR) detectors based on InAs/GaSb type II strained layer superlattices (T2SLs) can be significantly enhanced at select wavelengths by integrating the detector with a back-side illuminated plasmonic coupler. The application of a simple metal-T2SL structure directly on the GaSb substrate can result in radiation losses into the substrate due to the low refractive index of T2SL layer. However, insertion of a higher refractive index material, such as germanium (Ge), into the metal-SLS structure can confine the surface plasmon waveguide (SPW) modes to the surface. In this work, metal (Au)-Ge-T2SL structures are designed with an approximately 100 nm thick Ge layer. The T2SL layer utilized a p-i-n detector design with 8 monolayers (MLs) InAs/8 MLs GaSb. A plasmonic coupler was then realized inside the 300 μm circular apertures of these single element detectors by the formation of a corrugated metal (Au) surface. The T2SL single element detector integrated with an optimized plasmonic coupler design increased the quantum efficiency (QE) by a factor of three at an operating temperature of 77 K and 3 to 5 μm illumination wavelength, compared to a reference detector structure, and each structure exhibited the same level of dark current.

  5. Influence of infrared illumination on the characteristics of CdZnTe detectors

    SciTech Connect

    Ivanov, V.; Dorogov, P.; Loutchanski, A.

    2011-07-01

    Infrared (IR) radiation of proper wavelength deep penetrating inside the CdZnTe detector may interact with trapping centers and has a significant influence on the trapping-detrapping processes of charge carriers from traps, thereby influencing charge collection efficiency in the detector. We studied the effect of infrared (IR) illumination on the characteristics of planar and quasi-hemispherical CdZnTe detectors. These results show that the near bandgap IR illumination significantly affects the detectors characteristics. By selecting a wavelength and intensity of illumination, detectors spectrometric characteristics can be significantly improved. Improvement of spectrometric characteristics is due to better uniformity of charge collection on the detector volume, as evidenced by the improvement in the total absorption peak symmetry and shape of the output pulses. The degree of improvement is different for various detectors depending on the characteristics of source material used for detector fabrication and theirs dimensions. For example, a detector of sizes 10 x 10 x 5 mm{sup 3} with an initial energy resolution (FWHM) of 20.6 keV at 662 keV under IR illumination was improved up to 9.1 keV, but a detector of sizes 5 x 5 x 2.5 mm{sup 3} with an initial energy resolution (FWHM) of 7.1 keV can be improved up to 4.8 keV. The IR illumination with a properly chosen intensity improves spectrometric characteristic in a wide range of energies without any losses of registration effectiveness. IR Illumination was practically performed using conventional GaAlAs IR LEDs with different peak wavelengths of emitted radiation. (authors)

  6. Synchrotron-based EUV lithography illuminator simulator

    DOEpatents

    Naulleau, Patrick P.

    2004-07-27

    A lithographic illuminator to illuminate a reticle to be imaged with a range of angles is provided. The illumination can be employed to generate a pattern in the pupil of the imaging system, where spatial coordinates in the pupil plane correspond to illumination angles in the reticle plane. In particular, a coherent synchrotron beamline is used along with a potentially decoherentizing holographic optical element (HOE), as an experimental EUV illuminator simulation station. The pupil fill is completely defined by a single HOE, thus the system can be easily modified to model a variety of illuminator fill patterns. The HOE can be designed to generate any desired angular spectrum and such a device can serve as the basis for an illuminator simulator.

  7. Visible and infrared multispectral illumination concept based on Galilean collimation systems: IACATS illumination source

    NASA Astrophysics Data System (ADS)

    Ramos Zapata, Gonzalo; Belenguer Dávila, Tomás; Pastor Santos, Carmen; Restrepo Gómez, René; González Alvarado, Concepción; Laguna Hernández, Hugo; Astolfi Carbonell, Antonio; Moreno Raso, Javier; Argelaguet, Heribert; Serrano, Javier

    2010-07-01

    A LED based illumination system in which five Galilean collimation systems have been used is reported on. It is part of a turbulence simulator for the evaluation of on ground telescopes instrumentation developed by INTA (optics) and LIDAX (opto-mechanics) for the IAC called IACATS. The illumination requirements (some visible and infrared lines) allow the use of five different LEDs (red, green, blue and two infrareds). In order to optimize the illumination level of each wavelength, a Galilean collimating optical configuration was constructed for each wavelength channel. The IACATS instrument simulates a scene consisting of a set of different binary stars simulating the required angular separation between them, ant their spectral characteristics. As a result, a visible and infrared multi-spectral illumination system has been integrated as a part of the turbulence simulator, and the features (opto-mechanical) and illumination characteristics are described in the following lines.

  8. Carrier diffusion limited MTF of a back-illuminated pv detector array

    NASA Astrophysics Data System (ADS)

    Gupta, Sudha; Gopal, Vishnu; Chhabra, K. C.

    Carrier diffusion limited MTF of a back-illuminated HgCdTe-PV detector array has been calculated by including the multiple reflections within a CdTe-HgCdTe structure. Results of these calculations show that there is only a marginal improvement in MTF. The gain in quantum efficiency can however become substantial if the unilluminated surface is made strongly reflecting.

  9. Template based illumination compensation algorithm for multiview video coding

    NASA Astrophysics Data System (ADS)

    Li, Xiaoming; Jiang, Lianlian; Ma, Siwei; Zhao, Debin; Gao, Wen

    2010-07-01

    Recently multiview video coding (MVC) standard has been finalized as an extension of H.264/AVC by Joint Video Team (JVT). In the project Joint Multiview Video Model (JMVM) for the standardization, illumination compensation (IC) is adopted as a useful tool. In this paper, a novel illumination compensation algorithm based on template is proposed. The basic idea of the algorithm is that the illumination of the current block has a strong correlation with its adjacent template. Based on this idea, firstly a template based illumination compensation method is presented, and then a template models selection strategy is devised to improve the illumination compensation performance. The experimental results show that the proposed algorithm can improve the coding efficiency significantly.

  10. Magnetotransport in very long wave infrared quantum cascade detectors: Analyzing the current with and without illumination

    SciTech Connect

    Jasnot, François-Régis; Maëro, Simon; Vaulchier, Louis-Anne de; Guldner, Yves; Carosella, Francesca; Ferreira, Robson; Delga, Alexandre; Doyennette, Laetitia; Berger, Vincent; Carras, Mathieu

    2013-12-04

    Current measurements of current have been performed on a very long wave infrared quantum cascade detector under magnetic field under both dark and light conditions. The analysis of dark current as a function of temperature highlights three regimes of transport. Under illumination, the model developed is in agreement with the oscillatory component of the experimental magnetophotocurrent. It allows to identify the key points controlling the electronic transport: crucial role of extraction, location of ionized impurities and scattering mechanisms involved in the structure. This work is valuable for the future conception of high-performance quantum cascade detectors in the infrared range.

  11. Exemplar-Based Color Constancy and Multiple Illumination.

    PubMed

    Joze, Hamid Reza Vaezi; Drew, Mark S

    2014-05-01

    Exemplar-based learning or, equally, nearest neighbor methods have recently gained interest from researchers in a variety of computer science domains because of the prevalence of large amounts of accessible data and storage capacity. In computer vision, these types of technique have been successful in several problems such as scene recognition, shape matching, image parsing, character recognition, and object detection. Applying the concept of exemplar-based learning to the problem of color constancy seems odd at first glance since, in the first place, similar nearest neighbor images are not usually affected by precisely similar illuminants and, in the second place, gathering a dataset consisting of all possible real-world images, including indoor and outdoor scenes and for all possible illuminant colors and intensities, is indeed impossible. In this paper, we instead focus on surfaces in the image and address the color constancy problem by unsupervised learning of an appropriate model for each training surface in training images. We find nearest neighbor models for each surface in a test image and estimate its illumination based on comparing the statistics of pixels belonging to nearest neighbor surfaces and the target surface. The final illumination estimation results from combining these estimated illuminants over surfaces to generate a unique estimate. We show that it performs very well, for standard datasets, compared to current color constancy algorithms, including when learning based on one image dataset is applied to tests from a different dataset. The proposed method has the advantage of overcoming multi-illuminant situations, which is not possible for most current methods since they assume the color of the illuminant is constant all over the image. We show a technique to overcome the multiple illuminant situation using the proposed method and test our technique on images with two distinct sources of illumination using a multiple-illuminant color constancy

  12. Method for growing a back surface contact on an imaging detector used in conjunction with back illumination

    NASA Technical Reports Server (NTRS)

    Blacksberg, Jordana (Inventor); Hoenk, Michael Eugene (Inventor); Nikzad, Shouleh (Inventor)

    2010-01-01

    A method is provided for growing a back surface contact on an imaging detector used in conjunction with back illumination. In operation, an imaging detector is provided. Additionally, a back surface contact (e.g. a delta-doped layer, etc.) is grown on the imaging detector utilizing a process that is performed at a temperature less than 450 degrees Celsius.

  13. Indirectly illuminated X-ray area detector for X-ray photon correlation spectroscopy.

    PubMed

    Shinohara, Yuya; Imai, Ryo; Kishimoto, Hiroyuki; Yagi, Naoto; Amemiya, Yoshiyuki

    2010-11-01

    An indirectly illuminated X-ray area detector is employed for X-ray photon correlation spectroscopy (XPCS). The detector consists of a phosphor screen, an image intensifier (microchannel plate), a coupling lens and either a CCD or CMOS image sensor. By changing the gain of the image intensifier, both photon-counting and integrating measurements can be performed. Speckle patterns with a high signal-to-noise ratio can be observed in a single shot in the integrating mode, while XPCS measurement can be performed with much fewer photons in the photon-counting mode. By switching the image sensor, various combinations of frame rate, dynamic range and active area can be obtained. By virtue of these characteristics, this detector can be used for XPCS measurements of various types of samples that show slow or fast dynamics, a high or low scattering intensity, and a wide or narrow range of scattering angles. PMID:20975218

  14. Preliminary results for the design, fabrication, and performance of a backside-illuminated avalanche drift detector

    NASA Astrophysics Data System (ADS)

    Qiao, Yun; Liang, Kun; Chen, Wen-Fei; Han, De-Jun

    2013-10-01

    The detection of low-level light is a key technology in various experimental scientific studies. As a photon detector, the silicon photomultiplier (SiPM) has gradually become an alternative to the photomultiplier tube (PMT) in many applications in high-energy physics, astroparticle physics, and medical imaging because of its high photon detection efficiency (PDE), good resolution for single-photon detection, insensitivity to magnetic field, low operating voltage, compactness, and low cost. However, primarily because of the geometric fill factor, the PDE of most SiPMs is not very high; in particular, for those SiPMs with a high density of micro cells, the effective area is small, and the bandwidth of the light response is narrow. As a building block of the SiPM, the concept of the backside-illuminated avalanche drift detector (ADD) was first proposed by the Max Planck Institute of Germany eight years ago; the ADD is promising to have high PDE over the full energy range of optical photons, even ultraviolet light and X-ray light, and because the avalanche multiplication region is very small, the ADD is beneficial for the fabrication of large-area SiPMs. However, because of difficulties in design and fabrication, no significant progress had been made, and the concept had not yet been verified. In this paper, preliminary results in the design, fabrication, and performance of a backside-illuminated ADD are reported; the difficulties in and limitations to the backside-illuminated ADD are analyzed.

  15. Research on infrared imaging illumination model based on materials

    NASA Astrophysics Data System (ADS)

    Hu, Hai-he; Feng, Chao-yin; Guo, Chang-geng; Zheng, Hai-jing; Han, Qiang; Hu, Hai-yan

    2013-09-01

    In order to effectively simulate infrared features of the scene and infrared high light phenomenon, Based on the visual light illumination model, according to the optical property of all material types in the scene, the infrared imaging illumination models are proposed to fulfill different materials: to the smooth material with specular characteristic, adopting the infrared imaging illumination model based on Blinn-Phone reflection model and introducing the self emission; to the ordinary material which is similar to black body without highlight feature, ignoring the computation of its high light reflection feature, calculating simply the material's self emission and its reflection to the surrounding as its infrared imaging illumination model, the radiation energy under zero range of visibility can be obtained according to the above two models. The OpenGl rendering technology is used to construct infrared scene simulation system which can also simulate infrared electro-optical imaging system, then gets the synthetic infrared images from any angle of view of the 3D scenes. To validate the infrared imaging illumination model, two typical 3D scenes are made, and their infrared images are calculated to compare and contrast with the real collected infrared images obtained by a long wave infrared band imaging camera. There are two major points in the paper according to the experiment results: firstly, the infrared imaging illumination models are capable of producing infrared images which are very similar to those received by thermal infrared camera; secondly, the infrared imaging illumination models can simulate the infrared specular feature of relative materials and common infrared features of general materials, which shows the validation of the infrared imaging illumination models. Quantitative analysis shows that the simulation images are similar to the collected images in the aspects of main features, but their histogram distribution does not match very well, the

  16. Track analysis of laser-illuminated etched track detectors using an opto-digital imaging system

    NASA Astrophysics Data System (ADS)

    Eghan, Moses J.; Buah-Bassuah, Paul K.; Oppon, Osborne C.

    2007-11-01

    An opto-digital imaging system for counting and analysing tracks on a LR-115 detector is described. One batch of LR-115 track detectors was irradiated with Am-241 for a determined period and distance for linearity test and another batch was exposed to radon gas. The laser-illuminated etched track detector area was imaged, digitized and analysed by the system. The tracks that were counted on the opto-digital system with the aid of media cybernetics software as well as spark gap counter showed comparable track density results ranging between 1500 and 2750 tracks cm-2 and 65 tracks cm-2 in the two different batch detector samples with 0.5% and 1% track counts, respectively. Track sizes of the incident alpha particles from the radon gas on the LR-115 detector demonstrating different track energies are statistically and graphically represented. The opto-digital imaging system counts and measures other track parameters at an average process time of 3-5 s.

  17. Correlated Observations of Epithermal Neutrons and Polar Illumination for Orbital Neutron Detectors

    NASA Technical Reports Server (NTRS)

    McClanahan, T. P.; Mitrofanov, I. G.; Boynton, W. V.; Chin, G.; Droege, G.; Evans, L. G.; Garvin, J.; Harshman, K.; Malakhov, A.; Livengood, T.; Milikh, G. M.; Namkung, M.; Nandikotkur, G.; Neumann, G.; Smith, D.; Sagdeev, R.; Sanin, A. G.; Starr, R. D.; Trombka, J. I.

    2012-01-01

    We correlate Lunar Reconnaisance Orbiter's (LRO) Lunar Exploration Neutron Detector (LEND) and the Lunar Prospector Neutron Spectrometer's (LPNS) orbital epithermal neutron maps of the Lunar high-latitudes with co-registered illumination maps derived from the Lunar Orbiter Laser Altimeter (LOLA) topography. Epithermal neutron count rate maps were derived from the LEND: 1) Collimated Sensor for Epithermal Neutrons, CSETNI-4 2) Uncollimated Sensor for Epithermal Neutrons, SETN and the Uncollimated Lunar Prospector: 3) Low-altitude and 4) High-altitude mapping phases. In this abstract we illustrate 1) and 3) and include 2) and 4) in our presentation. The correlative study provides unique perspectives on the regional epithermal neutron fluences from the Lunar polar regions under different detector and altitude configurations.

  18. Effects of sub-bandgap illumination on electrical properties and detector performances of CdZnTe:In

    SciTech Connect

    Xu, Lingyan; Jie, Wanqi Zha, Gangqiang Feng, Tao; Wang, Ning; Xi, Shouzhi; Fu, Xu; Zhang, Wenlong; Xu, Yadong; Wang, Tao

    2014-06-09

    The effects of sub-bandgap illumination on electrical properties of CdZnTe:In crystals and spectroscopic performances of the fabricated detectors were discussed. The excitation process of charge carriers through thermal and optical transitions at the deep trap could be described by the modified Shockley-Read-Hall model. The ionization probability of the deep donor shows an increase under illumination, which should be responsible for the variation of electrical properties within CdZnTe bulk materials with infrared (IR) irradiation. By applying Ohm's law, diffusion model and interfacial layer-thermionic-diffusion theory, we obtain the decrease of bulk resistivity and the increase of space charge density in the illuminated crystals. Moreover, the illumination induced ionization will further contribute to improving carrier transport property and charge collection efficiency. Consequently, the application of IR irradiation in the standard working environment is of great significance to improve the spectroscopic characteristics of CdZnTe radiation detectors.

  19. Nanowire-based detector

    DOEpatents

    Berggren, Karl K; Hu, Xiaolong; Masciarelli, Daniele

    2014-06-24

    Systems, articles, and methods are provided related to nanowire-based detectors, which can be used for light detection in, for example, single-photon detectors. In one aspect, a variety of detectors are provided, for example one including an electrically superconductive nanowire or nanowires constructed and arranged to interact with photons to produce a detectable signal. In another aspect, fabrication methods are provided, including techniques to precisely reproduce patterns in subsequently formed layers of material using a relatively small number of fabrication steps. By precisely reproducing patterns in multiple material layers, one can form electrically insulating materials and electrically conductive materials in shapes such that incoming photons are redirected toward a nearby electrically superconductive materials (e.g., electrically superconductive nanowire(s)). For example, one or more resonance structures (e.g., comprising an electrically insulating material), which can trap electromagnetic radiation within its boundaries, can be positioned proximate the nanowire(s). The resonance structure can include, at its boundaries, electrically conductive material positioned proximate the electrically superconductive nanowire such that light that would otherwise be transmitted through the sensor is redirected toward the nanowire(s) and detected. In addition, electrically conductive material can be positioned proximate the electrically superconductive nanowire (e.g. at the aperture of the resonant structure), such that light is directed by scattering from this structure into the nanowire.

  20. Robust illumination-invariant tracking algorithm based on HOGs

    NASA Astrophysics Data System (ADS)

    Miramontes-Jaramillo, Daniel; Kober, Vitaly; Díaz-Ramírez, Víctor H.

    2015-09-01

    Common tracking systems are usually affected by environmental and technical interferences such as non-uniform illumination, sensors' noise, geometrical scene distortion, etc. Among these issues, the former is particularly interesting because it destroys important spatial characteristics of objects in observed scenes. We propose a two-step tracking algorithm: first, preprocessing locally normalizes the illumination difference between the target object and observed frames; second, the normalized object is tracked by means of a designed template structure based on histograms of oriented gradients and kinematic prediction model. The algorithm performance is tested in terms of recognition and localization errors in real scenarios. In order to achieve high rate of the processing, we use GPU parallel processing technologies. Finally, our algorithm is compared with other state-of-the-art trackers.

  1. Graphene based GHz detectors

    NASA Astrophysics Data System (ADS)

    Boyd, Anthony K.; El Fatimy, Abdel; Barbara, Paola; Nath, Anindya; Campbell, Paul M.; Myers-Ward, Rachael; Daniels, Kevin; Gaskill, D. Kurt

    Graphene demonstrates great promise as a detector over a wide spectral range especially in the GHz range. This is because absorption is enhanced due to the Drude contribution. In the GHz range there are viable detection mechanisms for graphene devices. With this in mind, two types of GHz detectors are fabricated on epitaxial graphene using a lift off resist-based clean lithography process to produce low contact resistance. Both device types use asymmetry for detection, consistent with recent thoughts of the photothermoelectric effect (PTE) mechanism. The first is an antenna coupled device. It utilizes two dissimilar contact metals and the work function difference produces the asymmetry. The other device is a field effect transistor constructed with an asymmetric top gate that creates a PN junction and facilitates tuning the photovoltaic response. The response of both device types, tested from 100GHz to 170GHz, are reported. This work was sponsored by the U.S. Office of Naval Research (Award Number N000141310865).

  2. Image quality-based adaptive illumination normalisation for face recognition

    NASA Astrophysics Data System (ADS)

    Sellahewa, Harin; Jassim, Sabah A.

    2009-05-01

    Automatic face recognition is a challenging task due to intra-class variations. Changes in lighting conditions during enrolment and identification stages contribute significantly to these intra-class variations. A common approach to address the effects such of varying conditions is to pre-process the biometric samples in order normalise intra-class variations. Histogram equalisation is a widely used illumination normalisation technique in face recognition. However, a recent study has shown that applying histogram equalisation on well-lit face images could lead to a decrease in recognition accuracy. This paper presents a dynamic approach to illumination normalisation, based on face image quality. The quality of a given face image is measured in terms of its luminance distortion by comparing this image against a known reference face image. Histogram equalisation is applied to a probe image if its luminance distortion is higher than a predefined threshold. We tested the proposed adaptive illumination normalisation method on the widely used Extended Yale Face Database B. Identification results demonstrate that our adaptive normalisation produces better identification accuracy compared to the conventional approach where every image is normalised, irrespective of the lighting condition they were acquired.

  3. Space-based detectors

    NASA Astrophysics Data System (ADS)

    Sesana, A.; Weber, W. J.; Killow, C. J.; Perreur-Lloyd, M.; Robertson, D. I.; Ward, H.; Fitzsimons, E. D.; Bryant, J.; Cruise, A. M.; Dixon, G.; Hoyland, D.; Smith, D.; Bogenstahl, J.; McNamara, P. W.; Gerndt, R.; Flatscher, R.; Hechenblaikner, G.; Hewitson, M.; Gerberding, O.; Barke, S.; Brause, N.; Bykov, I.; Danzmann, K.; Enggaard, A.; Gianolio, A.; Vendt Hansen, T.; Heinzel, G.; Hornstrup, A.; Jennrich, O.; Kullmann, J.; Møller-Pedersen, S.; Rasmussen, T.; Reiche, J.; Sodnik, Z.; Suess, M.; Armano, M.; Sumner, T.; Bender, P. L.; Akutsu, T.; Sathyaprakash, B. S.

    2014-12-01

    The parallel session C5 on Space-Based Detectors gave a broad overview over the planned space missions related to gravitational wave detection. Overviews of the revolutionary science to be expected from LISA was given by Alberto Sesana and Sasha Buchman. The launch of LISA Pathfinder (LPF) is planned for 2015. This mission and its payload "LISA Technology Package" will demonstrate key technologies for LISA. In this context, reference masses in free fall for LISA, and gravitational physics in general, was described by William Weber, laser interferometry at the pico-metre level and the optical bench of LPF was presented by Christian Killow and the performance of the LPF optical metrology system by Paul McNamara. While LPF will not yet be sensitive to gravitational waves, it may nevertheless be used to explore fundamental physics questions, which was discussed by Michele Armano. Some parts of the LISA technology that are not going to be demonstrated by LPF, but under intensive development at the moment, were presented by Oliver Jennrich and Oliver Gerberding. Looking into the future, Japan is studying the design of a mid-frequency detector called DECIGO, which was discussed by Tomotada Akutsu. Using atom interferometry for gravitational wave detection has also been recently proposed, and it was critically reviewed by Peter Bender. In the nearer future, the launch of GRACE Follow-On (for Earth gravity observation) is scheduled for 2017, and it will include a Laser Ranging Interferometer as technology demonstrator. This will be the first inter-spacecraft laser interferometer and has many aspects in common with the LISA long arm, as discussed by Andrew Sutton.

  4. Generalized mesh-based Monte Carlo for wide-field illumination and detection via mesh retessellation

    PubMed Central

    Yao, Ruoyang; Intes, Xavier; Fang, Qianqian

    2015-01-01

    Monte Carlo methods are commonly used as the gold standard in modeling photon transport through turbid media. With the rapid development of structured light applications, an accurate and efficient method capable of simulating arbitrary illumination patterns and complex detection schemes over large surface area is in great need. Here we report a generalized mesh-based Monte Carlo algorithm to support a variety of wide-field illumination methods, including spatial-frequency-domain imaging (SFDI) patterns and arbitrary 2-D patterns. The extended algorithm can also model wide-field detectors such as a free-space CCD camera. The significantly enhanced flexibility of source and detector modeling is achieved via a fast mesh retessellation process that combines the target domain and the source/detector space in a single tetrahedral mesh. Both simulations of complex domains and comparisons with phantom measurements are included to demonstrate the flexibility, efficiency and accuracy of the extended algorithm. Our updated open-source software is provided at http://mcx.space/mmc. PMID:26819826

  5. Tests of the Rockwell Si:As Back-Illuminated Blocked-Impurity Band (BIBIB) detectors

    NASA Technical Reports Server (NTRS)

    Wolf, J.; Groezinger, U.; Burgdorf, M.; Salama, A.

    1989-01-01

    Two arrays of Rockwell's Si:As back-illuminated blocked-impurity-band detectors were tested at the Max-Planck-Institute for Astronomy (MPIA) at low background and low temperature for possible use in the astronomical space experiment ISOPHOT. For these measurements special test equipment was put together. A cryostat was mechanically modified to accommodate the arrays and special peripheral electronics was added to a microprocessor system to drive the cold multiplexer and to acquire the output data. The first device, a 16x50 element array on a fan-out board was used to test individual pixels with a trans-impedance-amplifier at a photon background of 10(exp 8) Ph s(-1)cm(-2) and at temperatures of 2.7 to 4.4 K. The noise-equivalent-power NEP is in the range 5 - 7 x 10(exp -18) WHz(exp -1/2), the responsivity is less than or equal to 100 AW(exp -1)(f = 10 Hz). The second device was a 10x50 array including a cold readout electronics of switched FETs (SWIFET). Measurements of this array were done in a background range of 5 x 10(exp 5) to 5 x 10(exp 11) Ph s(exp-1)cm(exp-2) and at operating temperatures between 3.0 and 4.8 K. The NEP ranges from less than 10(exp -18) at the lowest background to 2 x 10(exp -16) WHz(exp -1/2) at the highest flux.

  6. Energy-Saving Tunnel Illumination System Based on LED's Intelligent Control

    NASA Astrophysics Data System (ADS)

    Guo, Shanshan; Gu, Hanting; Wu, Lan; Jiang, Shuixiu

    2011-02-01

    At present there is a lot of electric energy wastage in tunnel illumination, whose design is based on the maximum brightness outside and the maximum vehicle speed all year round. LED's energy consumption is low, and the control of its brightness is simple and effective. It can be quickly adjusted between 0-100% of its maximum brightness, and will not affect the service life. Therefore, using LED as tunnel's illumination source, we can achieve a good energy saving effect. According to real-time data acquisition of vehicle speed, traffic flow and brightness outside the tunnel, the auto real-time control of tunnel illumination can be achieved. And the system regulated the LED luminance by means of combination of LED power module and intelligent control module. The tunnel information was detected by inspection equipments, which included luminometer, vehicle detector, and received by RTU(Remote Terminal Unit), then synchronously transmitted to PC. After data processing, RTU emitted the dimming signal to the LED driver to adjust the brightness of LED. Despite the relatively high cost of high-power LED lights, the enormous energy-saving effect and the well-behaved controllability is beyond compare to other lighting devices.

  7. Space power by ground-based laser illumination

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    1991-01-01

    Reducing energy storage requirements of space power systems by illuminating the photovoltaic arrays with a remotely located laser system is addressed. It is proposed that large lasers be located on cloud-free sites at one or more ground locations and that large lenses or mirrors with adaptive optical correction be used to reduce the beam spread due to diffraction or atmospheric turbulence. During the eclipse periods or lunar night, the lasers illuminate the solar arrays to a level sufficient to provide operating power. Two applications are discussed: illumination of geosynchronous orbit satellites and illumination of a moonbase power system. Issues for photovoltaic receivers for such a system are discussed.

  8. Optimal illumination for visual enhancement based on color entropy evaluation.

    PubMed

    Shen, Junfei; Chang, Shengqian; Wang, Huihui; Zheng, Zhenrong

    2016-08-22

    Object visualization is influenced by the spectral distribution of an illuminant impinging upon it. In this paper, we proposed a color entropy evaluation method to provide the optimal illumination that best helps surgeons distinguish tissue features. The target-specific optimal illumination was obtained by maximizing the color entropy value of our sample tissue, whose spectral reflectance was measured using multispectral imaging. Sample images captured under optimal light were compared with that under commercial white light emitting diodes (3000K, 4000K and 5500K). Results showed images under the optimized illuminant had better visual performance such as more subtle details exhibited. PMID:27557255

  9. Analysis of crosstalk in front-illuminated InGaAs PIN hetero-junction photovoltaic infrared detector arrays

    NASA Astrophysics Data System (ADS)

    Li, Yongfu; Tang, Hengjing; Zhang, Kefeng; Li, Tao; Ning, Jinhua; Li, Xue; Gong, Haimei

    2009-07-01

    Here presented an experimental study on crosstalk in front illuminated planar and mesa-type InP/ InGaAs/ InP PIN hetero-junction photovoltaic infrared detector arrays. A scanning laser beam with an optical wavelength of 1310 nm coupled in a single-mode optical fiber placed within a few microns of the detector array surface was used to measure the crosstalk between the detector pixels. The crosstalk in the detector array varying with the distance between the incident laser spot and the measured pixel was shown. It is suggested that for the deep mesa-type arrays the dominating source of crosstalk is the light reflected from the detector substrate. And the dominating source of crosstalk that occurs in the planar type and shallow mesa type photovoltaic arrays is associated with photo-induced carries generated in the InGaAs absorption layer that diffuse laterally between neighbor pixels. These results gave out the possibility to optimize the detectors structures in order to reduce crosstalk.

  10. Adaptive Ambient Illumination Based on Color Harmony Model

    NASA Astrophysics Data System (ADS)

    Kikuchi, Ayano; Hirai, Keita; Nakaguchi, Toshiya; Tsumura, Norimichi; Miyake, Yoichi

    We investigated the relationship between ambient illumination and psychological effect by applying a modified color harmony model. We verified the proposed model by analyzing correlation between psychological value and modified color harmony score. Experimental results showed the possibility to obtain the best color for illumination using this model.

  11. A theoretical study of improved front-illuminated avalanche drift detectors

    NASA Astrophysics Data System (ADS)

    Liang, K.; Yuan, J.; Li, H. R.; Yang, R.; Han, D. J.

    2013-06-01

    In this study, two avalanche drift detector (ADD) concepts were theoretically examined. One was an improved detector with an avalanche photodiode (APD) collecting and double pn-junction drift configuration, and the other was a combination of an APD collecting and metal oxide semiconductor (MOS) drift structure. The feasibility of the devices was theoretically investigated by the ISE-TCAD program. ADD can be operated in either Geiger mode or linear mode. In the former case, the detector was found to be appropriate for a single photon avalanche detector with a large collection area. In the latter case, the detector was observed to be well suited to be coupled to a scintillator for gamma-ray detection. The improved ADDs are considered to have good performances in the short wavelength optical detection and in matching common scintillation crystals with more flexibility.

  12. Holographic illuminator for synchrotron-based projection lithography systems

    DOEpatents

    Naulleau, Patrick P.

    2005-08-09

    The effective coherence of a synchrotron beam line can be tailored to projection lithography requirements by employing a moving holographic diffuser and a stationary low-cost spherical mirror. The invention is particularly suited for use in an illuminator device for an optical image processing system requiring partially coherent illumination. The illuminator includes: (1) a synchrotron source of coherent or partially coherent radiation which has an intrinsic coherence that is higher than the desired coherence, (2) a holographic diffuser having a surface that receives incident radiation from said source, (3) means for translating the surface of the holographic diffuser in two dimensions along a plane that is parallel to the surface of the holographic diffuser wherein the rate of the motion is fast relative to integration time of said image processing system; and (4) a condenser optic that re-images the surface of the holographic diffuser to the entrance plane of said image processing system.

  13. Segmentation of cartridge cases based on illumination and focus series

    NASA Astrophysics Data System (ADS)

    Brein, Christoph

    2005-03-01

    Cartridge cases are important forensic specimen for the identification of weapons. The illumination conditions in the area of the firing pin marks and the breech face marks are very different and have to be treated separately to achieve an appropriate image quality for a visual inspection. Furthermore, not only the comparison but also the detection of the different and independent forensic marks should be automated. Both problems lead to the task of segmenting the different parts of the cartridge case bottom. In this paper, two automated approaches for the segmentation of cartridge cases are investigated and compared. The aim of the segmentation is the detection of the cartridge case border, the primer, the firing pin mark and additionally the letters around the primer. The first approach uses images obtained under systematically varied illumination conditions. After a preprocessing step a circle detection is applied to find the circular structures. The analysis of illumination series combined with a the connected components labeling method detect the letters. In a second approach, the depth-from-focus method is used to obtain 2½ D-data. This data is segmented applying a plane estimation technique. This results directly in the detection of the letters. Afterwards a circle detection algorithm identifies the parameters of the circular structures. With the introduced methods it is possible to optimize the illumination in order to realize a higher contrast of both the striation marks on the cartridge case surface and of the indentation of the firing pin independently. The improved image quality helps the examiner in identifying weapons and will help to improve the automated comparison strategies.

  14. Content-based fused off-axis object illumination direct-to-digital holography

    DOEpatents

    Price, Jeffery R.

    2006-05-02

    Systems and methods are described for content-based fused off-axis illumination direct-to-digital holography. A method includes calculating an illumination angle with respect to an optical axis defined by a focusing lens as a function of data representing a Fourier analyzed spatially heterodyne hologram; reflecting a reference beam from a reference mirror at a non-normal angle; reflecting an object beam from an object the object beam incident upon the object at the illumination angle; focusing the reference beam and the object beam at a focal plane of a digital recorder to from the content-based off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; and digitally recording the content based off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis.

  15. Modelling of illuminated current–voltage characteristics to evaluate leakage currents in long wavelength infrared mercury cadmium telluride photovoltaic detectors

    SciTech Connect

    Gopal, Vishnu E-mail: wdhu@mail.sitp.ac.cn; Qiu, WeiCheng; Hu, Weida E-mail: wdhu@mail.sitp.ac.cn

    2014-11-14

    The current–voltage characteristics of long wavelength mercury cadmium telluride infrared detectors have been studied using a recently suggested method for modelling of illuminated photovoltaic detectors. Diodes fabricated on in-house grown arsenic and vacancy doped epitaxial layers were evaluated for their leakage currents. The thermal diffusion, generation–recombination (g-r), and ohmic currents were found as principal components of diode current besides a component of photocurrent due to illumination. In addition, both types of diodes exhibited an excess current component whose growth with the applied bias voltage did not match the expected growth of trap-assisted-tunnelling current. Instead, it was found to be the best described by an exponential function of the type, I{sub excess} = I{sub r0} + K{sub 1} exp (K{sub 2} V), where I{sub r0}, K{sub 1}, and K{sub 2} are fitting parameters and V is the applied bias voltage. A study of the temperature dependence of the diode current components and the excess current provided the useful clues about the source of origin of excess current. It was found that the excess current in diodes fabricated on arsenic doped epitaxial layers has its origin in the source of ohmic shunt currents. Whereas, the source of excess current in diodes fabricated on vacancy doped epitaxial layers appeared to be the avalanche multiplication of photocurrent. The difference in the behaviour of two types of diodes has been attributed to the difference in the quality of epitaxial layers.

  16. Automatic illumination compensation device based on a photoelectrochemical biofuel cell driven by visible light.

    PubMed

    Yu, You; Han, Yanchao; Xu, Miao; Zhang, Lingling; Dong, Shaojun

    2016-04-28

    Inverted illumination compensation is important in energy-saving projects, artificial photosynthesis and some forms of agriculture, such as hydroponics. However, only a few illumination adjustments based on self-powered biodetectors that quantitatively detect the intensity of visible light have been reported. We constructed an automatic illumination compensation device based on a photoelectrochemical biofuel cell (PBFC) driven by visible light. The PBFC consisted of a glucose dehydrogenase modified bioanode and a p-type semiconductor cuprous oxide photocathode. The PBFC had a high power output of 161.4 μW cm(-2) and an open circuit potential that responded rapidly to visible light. It adjusted the amount of illumination inversely irrespective of how the external illumination was changed. This rational design of utilizing PBFCs provides new insights into automatic light adjustable devices and may be of benefit to intelligent applications. PMID:27076202

  17. Capacity analyze of WDM indoor visible light communication based on LED for standard illumination

    NASA Astrophysics Data System (ADS)

    Huang, Heqing; Tang, Yi; Cui, Lu; Zhu, Qingwei; Luo, Jiabin

    2015-08-01

    For indoor visible light communication (VLC) systems aim to achieve communication and illumination simultaneously, the channel capacity are significantly affected by illumination demands in actual scenarios. To enhance the system performance, the wavelength division multiplex (WDM) technique can be introduced. In this letter, we analyzed the demands of illuminance and chromaticity's influence on indoor WDM visible light communication system based on color light emitting diodes (LED). The spectra distribution, crosstalk and noise of WDM VLC system were analyzed and the relative optimal total channel capacity was obtained by optimizing the number of sub-channels and their intensity at standard illumination scenario. It's shown that by applying WDM technique, the total channel capacity of LED based VLC system can be about 4 times than the situation of single sub-channel, even with indoor illumination constraints. What's more, the system performance can be improved by adjusting appropriate number of sub-channels and their intensity accordingly.

  18. Automatic illumination compensation device based on a photoelectrochemical biofuel cell driven by visible light

    NASA Astrophysics Data System (ADS)

    Yu, You; Han, Yanchao; Xu, Miao; Zhang, Lingling; Dong, Shaojun

    2016-04-01

    Inverted illumination compensation is important in energy-saving projects, artificial photosynthesis and some forms of agriculture, such as hydroponics. However, only a few illumination adjustments based on self-powered biodetectors that quantitatively detect the intensity of visible light have been reported. We constructed an automatic illumination compensation device based on a photoelectrochemical biofuel cell (PBFC) driven by visible light. The PBFC consisted of a glucose dehydrogenase modified bioanode and a p-type semiconductor cuprous oxide photocathode. The PBFC had a high power output of 161.4 μW cm-2 and an open circuit potential that responded rapidly to visible light. It adjusted the amount of illumination inversely irrespective of how the external illumination was changed. This rational design of utilizing PBFCs provides new insights into automatic light adjustable devices and may be of benefit to intelligent applications.Inverted illumination compensation is important in energy-saving projects, artificial photosynthesis and some forms of agriculture, such as hydroponics. However, only a few illumination adjustments based on self-powered biodetectors that quantitatively detect the intensity of visible light have been reported. We constructed an automatic illumination compensation device based on a photoelectrochemical biofuel cell (PBFC) driven by visible light. The PBFC consisted of a glucose dehydrogenase modified bioanode and a p-type semiconductor cuprous oxide photocathode. The PBFC had a high power output of 161.4 μW cm-2 and an open circuit potential that responded rapidly to visible light. It adjusted the amount of illumination inversely irrespective of how the external illumination was changed. This rational design of utilizing PBFCs provides new insights into automatic light adjustable devices and may be of benefit to intelligent applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00759g

  19. Structured illumination temporal compressive microscopy

    PubMed Central

    Yuan, Xin; Pang, Shuo

    2016-01-01

    We present a compressive video microscope based on structured illumination with incoherent light source. The source-side illumination coding scheme allows the emission photons being collected by the full aperture of the microscope objective, and thus is suitable for the fluorescence readout mode. A 2-step iterative reconstruction algorithm, termed BWISE, has been developed to address the mismatch between the illumination pattern size and the detector pixel size. Image sequences with a temporal compression ratio of 4:1 were demonstrated. PMID:27231586

  20. Terahertz Detectors based on graphene

    NASA Astrophysics Data System (ADS)

    Gouider, Fathi; Salman, Majdi; Göthlich, Markus; Schmidt, Hennrik; Ahlers, Franz-J.; Haug, Rolf; Nachtwei, Georg

    2013-08-01

    In this study we present magnetotransport an magnetooptical data obtained in the magnetic field range 0T < B < 7T at detectors patterned in Corbino geometry on epitaxial graphene wafer using a Ge detector. We observed the cyclotron resonance of charge carriers in these wafers by measurement of the transmission of THz wafes through the unpatterned squares (about 4 × 4mm2) of the wafers as a function of the magnetic field B applied perpendicular to the wafer. Further, we performed measurements of the photocunductivity of graphene-based devices shaped in Corbino geometry, induced by terahertz (THz) radiation generated by a p-Ge laser (emitting in the energy range 7.5meV <= Eph <= 11meV). Our photoconductivity measurement imply that graphene devices are suitable for the detection of terahertz radiation.

  1. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    PubMed Central

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-01-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

  2. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    NASA Astrophysics Data System (ADS)

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-02-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

  3. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry.

    PubMed

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R; Chess, Jordan; McMorran, Benjamin J; Czarnik, Cory; Rose, Harald H; Ercius, Peter

    2016-01-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

  4. An Asynchronous Cellular Automata-Based Adaptive Illumination Facility

    NASA Astrophysics Data System (ADS)

    Bandini, Stefania; Bonomi, Andrea; Vizzari, Giuseppe; Acconci, Vito

    The term Ambient Intelligence refers to electronic environments that are sensitive and responsive to the presence of people; in the described scenario the environment itself is endowed with a set of sensors (to perceive humans or other physical entities such as dogs, bicycles, etc.), interacting with a set of actuators (lights) that choose their actions (i.e. state of illumination) in an attempt improve the overall experience of these users. The model for the interaction and action of sensors and actuators is an asynchronous Cellular Automata (CA) with memory, supporting a self-organization of the system as a response to the presence and movements of people inside it. The paper will introduce the model, as well as an ad hoc user interface for the specification of the relevant parameters of the CA transition rule that determines the overall system behaviour.

  5. Using gradient-based ray and candidate shadow maps for environmental illumination distribution estimation

    NASA Astrophysics Data System (ADS)

    Eem, Changkyoung; Kim, Iksu; Hong, Hyunki

    2015-07-01

    A method to estimate the environmental illumination distribution of a scene with gradient-based ray and candidate shadow maps is presented. In the shadow segmentation stage, we apply a Canny edge detector to the shadowed image by using a three-dimensional (3-D) augmented reality (AR) marker of a known size and shape. Then the hierarchical tree of the connected edge components representing the topological relation is constructed, and the connected components are merged, taking their hierarchical structures into consideration. A gradient-based ray that is perpendicular to the gradient of the edge pixel in the shadow image can be used to extract the shadow regions. In the light source detection stage, shadow regions with both a 3-D AR marker and the light sources are partitioned into candidate shadow maps. A simple logic operation between each candidate shadow map and the segmented shadow is used to efficiently compute the area ratio between them. The proposed method successively extracts the main light sources according to their relative contributions on the segmented shadows. The proposed method can reduce unwanted effects due to the sampling positions in the shadow region and the threshold values in the shadow edge detection.

  6. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    DOE PAGESBeta

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-02-29

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, makingmore » it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Ultimately, simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.« less

  7. Illumination-invariant image matching for autonomous UAV localisation based on optical sensing

    NASA Astrophysics Data System (ADS)

    Wan, Xue; Liu, Jianguo; Yan, Hongshi; Morgan, Gareth L. K.

    2016-09-01

    This paper presents an UAV (Unmanned Aerial Vehicle) localisation algorithm for its autonomous navigation based on matching between on-board UAV image sequences to a pre-installed reference satellite image. As the UAV images and the reference image are not necessarily taken under the same illumination condition, illumination-invariant image matching is essential. Based on the investigation of illumination-invariant property of Phase Correlation (PC) via mathematical derivation and experiments, we propose a PC based fast and robust illumination-invariant localisation algorithm for UAV navigation. The algorithm accurately determines the current UAV position as well as the next UAV position even the illumination condition of UAV on-board images is different from the reference satellite image. A Dirac delta function based registration quality assessment together with a risk alarming criterion is introduced to enable the UAV to perform self-correction in case the UAV deviates from the planned route. UAV navigation experiments using simulated terrain shading images and remote sensing images have demonstrated a robust high performance of the proposed PC based localisation algorithm under very different illumination conditions resulted from solar motion. The superiority of the algorithm, in comparison with two other widely used image matching algorithms, MI (Mutual Information) and NCC (Normalised Correlation Coefficient), is significant for its high matching accuracy and fast processing speed.

  8. Model-based beam control for illumination of remote objects

    NASA Astrophysics Data System (ADS)

    Chandler, Susan M.; Lukesh, Gordon W.; Voelz, David; Basu, Santasri; Sjogren, Jon A.

    2004-11-01

    On September 1, 2003, Nukove Scientific Consulting, together with partner New Mexico State University, began work on a Phase 1 Small Business Technology TRansfer (STTR) grant from the United States Air Force Office of Scientific Research (AFOSR). The purpose of the grant was to show the feasibility of taking Nukove's pointing estimation technique from a post-processing tool for estimation of laser system characteristics to a real-time tool usable in the field. Nukove's techniques for pointing, shape, and OCS estimation do not require an imaging sensor nor a target board, thus estimates may be made very quickly. To prove feasibility, Nukove developed an analysis tool RHINO (Real-time Histogram Interpretation of Numerical Observations) and successfully demonstrated the emulation of real-time, frame-by-frame estimation of laser system characteristics, with data streamed into the tool and the estimates displayed as they are made. The eventual objective will be to use the frame-by-frame estimates to allow for feedback to a fielded system. Closely associated with this, NMSU developed a laboratory testbed to illuminate test objects, collect the received photons, and stream the data into RHINO. The two coupled efforts clearly demonstrate the feasibility of real-time pointing control of a laser system.

  9. High-nitrogen-based pyrotechnics: perchlorate-free red- and green-light illuminants based on 5-aminotetrazole.

    PubMed

    Sabatini, Jesse J; Moretti, Jared D

    2013-09-16

    Prototype testing of perchlorate-free hand-held signal illuminants for the US Army's M126 A1 red-star and M195 green-star parachute illuminants are described. Although previous perchlorate-free variants for these items have been developed based on high-nitrogen compounds that are not readily available, the new formulations consist of anhydrous 5-aminotetrazole as the suitable perchlorate replacement. Compared to the perchlorate-containing control, the disclosed illuminants exhibited excellent stabilities toward various ignition stimuli and had excellent pyrotechnic performance. The illuminants are important from both military and civil fireworks perspectives, as the perchlorate-free nature of the illuminants adequately address environmental concerns associated with perchlorate-containing red- and green-light-emitting illuminants. PMID:23950104

  10. Laboratory implementation of edge illumination X-ray phase-contrast imaging with energy-resolved detectors

    NASA Astrophysics Data System (ADS)

    Diemoz, P. C.; Endrizzi, M.; Vittoria, F. A.; Hagen, C. K.; Kallon, G.; Basta, D.; Marenzana, M.; Delogu, P.; Vincenzi, A.; De Ruvo, L.; Spandre, G.; Brez, A.; Bellazzini, R.; Olivo, A.

    2015-03-01

    Edge illumination (EI) X-ray phase-contrast imaging (XPCI) has potential for applications in different fields of research, including materials science, non-destructive industrial testing, small-animal imaging, and medical imaging. One of its main advantages is the compatibility with laboratory equipment, in particular with conventional non-microfocal sources, which makes its exploitation in normal research laboratories possible. In this work, we demonstrate that the signal in laboratory implementations of EI can be correctly described with the use of the simplified geometrical optics. Besides enabling the derivation of simple expressions for the sensitivity and spatial resolution of a given EI setup, this model also highlights the EI's achromaticity. With the aim of improving image quality, as well as to take advantage of the fact that all energies in the spectrum contribute to the image contrast, we carried out EI acquisitions using a photon-counting energy-resolved detector. The obtained results demonstrate that this approach has great potential for future laboratory implementations of EI.

  11. Digital micromirror device-based laser-illumination Fourier ptychographic microscopy.

    PubMed

    Kuang, Cuifang; Ma, Ye; Zhou, Renjie; Lee, Justin; Barbastathis, George; Dasari, Ramachandra R; Yaqoob, Zahid; So, Peter T C

    2015-10-19

    We report a novel approach to Fourier ptychographic microscopy (FPM) by using a digital micromirror device (DMD) and a coherent laser source (532 nm) for generating spatially modulated sample illumination. Previously demonstrated FPM systems are all based on partially-coherent illumination, which offers limited throughput due to insufficient brightness. Our FPM employs a high power coherent laser source to enable shot-noise limited high-speed imaging. For the first time, a digital micromirror device (DMD), imaged onto the back focal plane of the illumination objective, is used to generate spatially modulated sample illumination field for ptychography. By coding the on/off states of the micromirrors, the illumination plane wave angle can be varied at speeds more than 4 kHz. A set of intensity images, resulting from different oblique illuminations, are used to numerically reconstruct one high-resolution image without obvious laser speckle. Experiments were conducted using a USAF resolution target and a fiber sample, demonstrating high-resolution imaging capability of our system. We envision that our approach, if combined with a coded-aperture compressive-sensing algorithm, will further improve the imaging speed in DMD-based FPM systems. PMID:26480361

  12. Evaluating Work-Based Learning: Insights from an Illuminative Evaluation Study of Work-Based Learning in a Vocational Qualification

    ERIC Educational Resources Information Center

    van Rensburg, Estelle

    2008-01-01

    This article outlines an illuminative evaluation study of the work-based module in a vocational qualification in Animal Health offered for the paraveterinary industry by a distance education institution in South Africa. In illuminative evaluation, a programme is studied by qualitative methods to gain an in-depth understanding of its "instructional…

  13. Photon-counting gamma camera based on columnar CsI(Tl) optically coupled to a back-illuminated CCD

    PubMed Central

    Miller, Brian W.; Barber, H. Bradford; Barrett, Harrison H.; Chen, Liying; Taylor, Sean J.

    2010-01-01

    Recent advances have been made in a new class of CCD-based, single-photon-counting gamma-ray detectors which offer sub-100 μm intrinsic resolutions.1–7 These detectors show great promise in small-animal SPECT and molecular imaging and exist in a variety of configurations. Typically, a columnar CsI(Tl) scintillator or a radiography screen (Gd2O2S:Tb) is imaged onto the CCD. Gamma-ray interactions are seen as clusters of signal spread over multiple pixels. When the detector is operated in a charge-integration mode, signal spread across pixels results in spatial-resolution degradation. However, if the detector is operated in photon-counting mode, the gamma-ray interaction position can be estimated using either Anger (centroid) estimation or maximum-likelihood position estimation resulting in a substantial improvement in spatial resolution.2 Due to the low-light-level nature of the scintillation process, CCD-based gamma cameras implement an amplification stage in the CCD via electron multiplying (EMCCDs)8–10 or via an image intensifier prior to the optical path.1 We have applied ideas and techniques from previous systems to our high-resolution LumiSPECT detector.11, 12 LumiSPECT is a dual-modality optical/SPECT small-animal imaging system which was originally designed to operate in charge-integration mode. It employs a cryogenically cooled, high-quantum-efficiency, back-illuminated large-format CCD and operates in single-photon-counting mode without any intermediate amplification process. Operating in photon-counting mode, the detector has an intrinsic spatial resolution of 64 μm compared to 134 μm in integrating mode. PMID:20890397

  14. Amorphous Silicon Based Neutron Detector

    SciTech Connect

    Xu, Liwei

    2004-12-12

    Various large-scale neutron sources already build or to be constructed, are important for materials research and life science research. For all these neutron sources, neutron detectors are very important aspect. However, there is a lack of a high-performance and low-cost neutron beam monitor that provides time and temporal resolution. The objective of this SBIR Phase I research, collaboratively performed by Midwest Optoelectronics, LLC (MWOE), the University of Toledo (UT) and Oak Ridge National Laboratory (ORNL), is to demonstrate the feasibility for amorphous silicon based neutron beam monitors that are pixilated, reliable, durable, fully packaged, and fabricated with high yield using low-cost method. During the Phase I effort, work as been focused in the following areas: 1) Deposition of high quality, low-defect-density, low-stress a-Si films using very high frequency plasma enhanced chemical vapor deposition (VHF PECVD) at high deposition rate and with low device shunting; 2) Fabrication of Si/SiO2/metal/p/i/n/metal/n/i/p/metal/SiO2/ device for the detection of alpha particles which are daughter particles of neutrons through appropriate nuclear reactions; and 3) Testing of various devices fabricated for alpha and neutron detection; As the main results: · High quality, low-defect-density, low-stress a-Si films have been successfully deposited using VHF PECVD on various low-cost substrates; · Various single-junction and double junction detector devices have been fabricated; · The detector devices fabricated have been systematically tested and analyzed. · Some of the fabricated devices are found to successfully detect alpha particles. Further research is required to bring this Phase I work beyond the feasibility demonstration toward the final prototype devices. The success of this project will lead to a high-performance, low-cost, X-Y pixilated neutron beam monitor that could be used in all of the neutron facilities worldwide. In addition, the technologies

  15. A source of illumination for low-noise ‘Violin-Mode’ shadow sensors, intended for use in interferometric gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Lockerbie, N. A.; Tokmakov, K. V.; Strain, K. A.

    2014-12-01

    A low-noise source of illumination is described for shadow sensors having a displacement sensitivity of (69  ±  13) picometres (rms)/√Hz, at 500 Hz, over a measuring span of ±0.1 mm. These sensors were designed to detect ‘Violin-Mode’ resonances in the suspension fibres of the test-masses/mirrors for the Advanced LIGO (Laser Interferometer Gravitational wave Observatory) gravitational wave detectors. The source of illumination (emitter) described here used a single column of 8 × miniature near infrared LEDs (λ = 890 nm). These emitters cast the shadows of 400 μm diameter fused silica suspension fibres onto their complementary shadow-displacement detectors, located at a distance of 74 fibre diameters (29.6 mm) behind the axes of the fibres themselves. Violin-Mode vibrations of each fibre were sensed as differential ac photocurrents in the corresponding ‘split-photodiode’ detector. This paper describes the design, construction, noise analysis, and measures that were taken in the conception of the emitters, in order to produce high-contrast shadows at such distant detectors. In this way it proved possible to obtain, simultaneously, a very high transfer sensitivity to Violin-Mode vibration of the fibres, and a very low level of detection noise—close to the fundamental shot noise limit—whilst remaining within the constraints of this simple design of emitter. The shadow detector is described in an accompanying paper.

  16. Short-wavelength infrared imaging using low dark current InGaAs detector arrays and vertical-cavity surface-emitting laser illuminators

    NASA Astrophysics Data System (ADS)

    Macdougal, Michael; Geske, Jon; Wang, Chad; Follman, David

    2011-06-01

    We describe the factors that go into the component choices for a short wavelength IR (SWIR) imager, which include the SWIR sensor, the lens, and the illuminator. We have shown the factors for reducing dark current, and shown that we can achieve well below 1.5 nA/cm2 for 15 μm devices at 7 °C. In addition, we have mated our InGaAs detector arrays to 640×512 readout integrated integrated circuits to make focal plane arrays (FPAs). The resulting FPAs are capable of imaging photon fluxes with wavelengths between 1 and 1.6 μm at low light levels. The dark current associated with these FPAs is extremely low, exhibiting a mean dark current density of 0.26 nA/cm2 at 0 °C. Noise due to the readout can be reduced from 95 to 57 electrons by using off-chip correlated double sampling. In addition, Aerius has developed laser arrays that provide flat illumination in scenes that are normally light-starved. The illuminators have 40% wall-plug efficiency and provide low-speckle illumination, and provide artifact-free imagery versus conventional laser illuminators.

  17. Mitigating illumination gradients in a SAR image based on the image data and antenna beam pattern

    SciTech Connect

    Doerry, Armin W.

    2013-04-30

    Illumination gradients in a synthetic aperture radar (SAR) image of a target can be mitigated by determining a correction for pixel values associated with the SAR image. This correction is determined based on information indicative of a beam pattern used by a SAR antenna apparatus to illuminate the target, and also based on the pixel values associated with the SAR image. The correction is applied to the pixel values associated with the SAR image to produce corrected pixel values that define a corrected SAR image.

  18. Development of two-channel prototype ITER vacuum ultraviolet spectrometer with back-illuminated charge-coupled device and microchannel plate detectors

    SciTech Connect

    Seon, C. R.; Choi, S. H.; Cheon, M. S.; Pak, S.; Lee, H. G.; Biel, W.; Barnsley, R.

    2010-10-15

    A vacuum ultraviolet (VUV) spectrometer of a five-channel spectral system is designed for ITER main plasma impurity measurement. To develop and verify the system design, a two-channel prototype system is fabricated with No. 3 (14.4-31.8 nm) and No. 4 (29.0-60.0 nm) among the five channels. The optical system consists of a collimating mirror to collect the light from source to slit, two holographic diffraction gratings with toroidal geometry, and two different electronic detectors. For the test of the prototype system, a hollow cathode lamp is used as a light source. To find the appropriate detector for ITER VUV system, two kinds of detectors of the back-illuminated charge-coupled device and the microchannel plate electron multiplier are tested, and their performance has been investigated.

  19. Plasma Panel Based Radiation Detectors

    SciTech Connect

    Friedman, Dr. Peter S.; Varner Jr, Robert L; Ball, Robert; Beene, James R; Ben Moshe, M.; Benhammou, Yan; Chapman, J. Wehrley; Etzion, E; Ferretti, Claudio; Bentefour, E; Levin, Daniel S.; Moshe, M.; Silver, Yiftah; Weaverdyck, Curtis; Zhou, Bing

    2013-01-01

    The plasma panel sensor (PPS) is a gaseous micropattern radiation detector under current development. It has many operational and fabrication principles common to plasma display panels (PDPs). It comprises a dense matrix of small, gas plasma discharge cells within a hermetically sealed panel. As in PDPs, it uses non-reactive, intrinsically radiation-hard materials such as glass substrates, refractory metal electrodes, and mostly inert gas mixtures. We are developing these devices primarily as thin, low-mass detectors with gas gaps from a few hundred microns to a few millimeters. The PPS is a high gain, inherently digital device with the potential for fast response times, fine position resolution (< 50 m RMS) and low cost. In this paper we report here on prototype PPS experimental results in detecting betas, protons and cosmic muons, and we extrapolate on the PPS potential for applications including detection of alphas, heavy-ions at low to medium energy, thermal neutrons and X-rays.

  20. Edge-moment-based color constancy using illumination-coherent regularized regression.

    PubMed

    Wu, Meng; Luo, Kai; Dang, Jianjun; Zhou, Jun

    2015-09-01

    Considering no previous literature reveals the effectiveness of image similarity coherent with corresponding illuminant in color constancy, we propose an edge-moment-based algorithm using regularized regression in an illumination-coherent space in a divide-and-conquer way. To represent the scene images, we adopt color edge moments which are then projected into an illumination-coherent space using canonical correlation analysis (CCA). Further, a mixture of Gaussians (MoG) model is exploited to construct consistent subspaces, in each of which an iterative l2-norm regularized regression is used to learn the correlation between edge moments and illuminants. In the testing phase, estimations from each subspace are fused in a soft way according to the posterior possibility of the test image caused by the MoG. Extensive experiments on the standard datasets including the intra- and inter-dataset evaluations show that our approach outperforms the state-of-the-art algorithms. PMID:26367440

  1. Multipoint side illuminated absorption based optical fiber sensor for relative humidity

    NASA Astrophysics Data System (ADS)

    Egalon, Claudio O.

    2013-09-01

    A side illuminated optical fiber sensor with three sensing points and an absorption-based indicator in the cladding was demonstrated for the first time. This device is easy to manufacture, uses leaky modes as the signal carrier and can measure RH in air, soil, concrete and other environments. So far, only side illuminated fluorescence sensors have been reported. They were thought, erroneously, to have their entire signal generated by evanescent wave coupling when, in fact, leaky modes also play an important role. This, coupled to the prevailing misconception that leaky modes propagate for very short lengths of fiber, prevented the earlier discovery of this absorption-based configuration. A 25 cm long fiber, with a cladding doped with an absorption dye sensitive to Relative Humidity (RH), was used in this demonstration. The fiber was side illuminated by a broadband LED, a fraction of this light was absorbed by the cladding and the remaining light guided to the fiber tip as low loss leaky modes. A total of three sensors, two with three sensing points and one with two, were calibrated using a low cost photometer. The signal was linear, stable, increased with RH and had resolutions between 0.11% and 0.25% in RH. With 5 mm diameter LEDs, devices with at least two sensing points per centimeter of fiber can be easily fabricated resulting in sensors with a very high density of sensing points. Compared to the prevailing axial illumination approach, the side illuminated sensor was found to be far simpler and inexpensive.

  2. Smartphone-based fluorescence detector for mHealth.

    PubMed

    Balsam, Joshua; Bruck, Hugh Alan; Rasooly, Avraham

    2015-01-01

    We describe here a compact smartphone-based fluorescence detector for mHealth. A key element to achieving high sensitivity using low sensitivity phone cameras is a capillary array, which increases sensitivity by 100×. The capillary array was combined with a white LED illumination system to enable wide spectra fluorescent excitation in the range of 450-740 nm. The detector utilizes an orthographic projection system to form parallel light projection images from the capillaries at a close distance via an object-space telecentric lens configuration that reduces the total lens-to-object distance while maintaining uniformity in measurement between capillaries. To further increase the limit of detection (LOD), a computational image processing approach was employed to decrease the level of noise. This enables an additional 5-10× decrease in LOD. This smartphone-based detector was used to measure serial dilutions of fluorescein with a LOD of 1 nM with image stacking and 10 nM without image stacking, similar to the LOD obtained with a commercial plate reader. Moreover, the capillary array required a sample volume of less than 10 μl, which is an order of magnitude less than the 100 μl required for the plate reader.As fluorescence detection is widely used in sensitive biomedical assays, the approach described here has the potential to increase mHealth clinical utility, especially for telemedicine and for resource-poor settings in global health applications. PMID:25626543

  3. Low Power Ground-Based Laser Illumination for Electric Propulsion Applications

    NASA Technical Reports Server (NTRS)

    Lapointe, Michael R.; Oleson, Steven R.

    1994-01-01

    A preliminary evaluation of low power, ground-based laser powered electric propulsion systems is presented. A review of available and near-term laser, photovoltaic, and adaptive optic systems indicates that approximately 5-kW of ground-based laser power can be delivered at an equivalent one-sun intensity to an orbit of approximately 2000 km. Laser illumination at the proper wavelength can double photovoltaic array conversion efficiencies compared to efficiencies obtained with solar illumination at the same intensity, allowing a reduction in array mass. The reduced array mass allows extra propellant to be carried with no penalty in total spacecraft mass. The extra propellant mass can extend the satellite life in orbit, allowing additional revenue to be generated. A trade study using realistic cost estimates and conservative ground station viewing capability was performed to estimate the number of communication satellites which must be illuminated to make a proliferated system of laser ground stations economically attractive. The required number of satellites is typically below that of proposed communication satellite constellations, indicating that low power ground-based laser beaming may be commercially viable. However, near-term advances in low specific mass solar arrays and high energy density batteries for LEO applications would render the ground-based laser system impracticable.

  4. Field crop extraction robust to illumination variations based on specularity learning

    NASA Astrophysics Data System (ADS)

    Yu, Zhenghong; Li, Cuina; Zhou, Huabing

    2015-12-01

    In this paper, we proposed an illumination-invariant crop extraction method based on specularity learning. Several useful contextual cues including object appearance and location inspired by recognition mechanism of human beings were introduced and integrated to machine learning architecture, generating a well-trained highlight region classifier. Combing with the Hue-intensity Look-up table and super-pixel techniques, the classifier gives the final extraction result. Comparing experiment confirmed the validity and feasibility of our method.

  5. Improved efficacy of dendritic cell-based immunotherapy by cutaneous laser illumination

    PubMed Central

    Chen, Xinyuan; Zeng, Qiyan; Wu, Mei X.

    2012-01-01

    Purpose The present investigation demonstrates a convenient laser-based approach to enhance DC migration resulting in improved DC-based immunotherapy in murine models. Experimental design Influence of laser illumination on dermal tissue microenvironment and migration of DCs following intradermal injection were determined by whole-mount immunohistochemistry, transmission electron microscope, and flow cytometry. We also investigated in vivo expansion of cytotoxic T lymphocytes (CTLs) by flow cytometry, CTL activity by in vitro CTL assay, and anti-tumor efficacy of DC immunization following cutaneous laser illumination in both preventive and therapeutic tumor models. Results Laser illumination was found to significantly enlarge perforations in the peri-lymphatic basement membrane, disarray collagen fibers and disrupt cell-matrix interactions in the dermis. The altered dermal tissue microenvironment permitted more efficient migration of intradermally injected DCs from the dermis to the draining lymph nodes (dLNs). Laser illumination also slightly but significantly enhanced the expression of costimulatory molecule CD80 and MHC I on DCs injected into the skin, when compared to those DCs administered into sham-treated skin. As a result, more vigorous expansion of tumor-specific IFN-γ+CD8+ T lymphocytes and enhanced CTL activity against 4T1 but not irrelevant tumor cells were obtained in the laser-treated group over the control group. Laser-augmented DC immunization also completely abrogated early growth of 4T1 tumor and B16F10 melanoma in preventive tumor models and significantly extended the survival of 4T1-resected mice in a therapeutic tumor model. Conclusion These data suggest a simple, safe, laser-based approach to significantly enhance DC-based immunotherapy. PMID:22392913

  6. An Efficient Ant-Based Edge Detector

    NASA Astrophysics Data System (ADS)

    Aydın, Doğan

    An efficient ant-based edge detector is presented. It is based on the distribution of ants on an image, ants try to find possible edges by using a state transition function based on 5x5 edge structures. Visual comparisons show that the proposed method gives finer details and thinner edges at lesser computational times when compared to earlier ant-based approaches. When compared to standard edge detectors, it shows robustness to Gaussian and Salt & Pepper noise and provides finer details than others with same parameter set in both clear and noisy images.

  7. Ion chamber based neutron detectors

    DOEpatents

    Derzon, Mark S; Galambos, Paul C; Renzi, Ronald F

    2014-12-16

    A neutron detector with monolithically integrated readout circuitry, including: a bonded semiconductor die; an ion chamber formed in the bonded semiconductor die; a first electrode and a second electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; and the readout circuitry which is electrically coupled to the first and second electrodes. The bonded semiconductor die includes an etched semiconductor substrate bonded to an active semiconductor substrate. The readout circuitry is formed in a portion of the active semiconductor substrate. The ion chamber has a substantially planar first surface on which the first electrode is formed and a substantially planar second surface, parallel to the first surface, on which the second electrode is formed. The distance between the first electrode and the second electrode may be equal to or less than the 50% attenuation length for neutrons in the neutron absorbing material filling the ion chamber.

  8. Design of LED-based reflector-array module for specific illuminance distribution

    NASA Astrophysics Data System (ADS)

    Chen, Enguo; Yu, Feihong

    2013-02-01

    This paper presents an efficient and practical design method for a LED based reflector-array lighting module. Improving on previous designs, this method could offer higher design freedom to achieve specific illuminance distribution for actual lighting application and deal with the LED light intensity distribution while shortening the design time. The detailed design description of the lighting system is thoroughly investigated. To demonstrate the effectiveness of this method, an ultra-compact reflector-array module, which produces a rectangular illumination area with a large aspect ratio, is specially designed to meet the high-demanding requirements of industrial lighting application. Design results show that most LED emitting energy could be collected into the required lighting region while higher-brightness and better-uniformity are simultaneously available within the focus region. It is expected that this method will have great potential for other lighting applications.

  9. Chroma key without color restrictions based on asynchronous amplitude modulation of background illumination on retroreflective screens

    NASA Astrophysics Data System (ADS)

    Vidal, Borja; Lafuente, Juan A.

    2016-03-01

    A simple technique to avoid color limitations in image capture systems based on chroma key video composition using retroreflective screens and light-emitting diodes (LED) rings is proposed and demonstrated. The combination of an asynchronous temporal modulation onto the background illumination and simple image processing removes the usual restrictions on foreground colors in the scene. The technique removes technical constraints in stage composition, allowing its design to be purely based on artistic grounds. Since it only requires adding a very simple electronic circuit to widely used chroma keying hardware based on retroreflective screens, the technique is easily applicable to TV and filming studios.

  10. Assessment of color search performance in photopic and mesopic illuminances based on color identification data

    NASA Astrophysics Data System (ADS)

    Ishida, Taiichiro

    2002-06-01

    Color is an effective attribute as an aid to a visual task. Appearance of colors, however, remarkably changes with viewing conditions. In particular, lighting environment has strong effects on the appearance of surface colors. To use colors effectively, we must know how colors are identified under various lighting conditions. In our previous studies, we obtained the data on identification of colors under illuminances from photopic to mesopic levels. In this study we examined performance of a color related searching task under photopic and mesopic illuminance levels, and evaluated it based on the color identification data. Subjects searched the target three-digits printed on a card from among 45 cards. At the same time, a color chip was pasted on each plate as a clue. Before each trial the subjects were informed of the number and color name for the target on that trial. If the subjects could identify colors properly,.the searching performance must be improved. As might be expected, the performance of the task declined with decreasing illuminances and size of the color chip. It was found that the searching performance correlated with probability of being identified as the target color.

  11. A smartphone-based chip-scale microscope using ambient illumination

    PubMed Central

    Lee, Seung Ah; Yang, Changhuei

    2014-01-01

    Portable chip-scale microscopy devices can potentially address various imaging needs in mobile healthcare and environmental monitoring. Here, we demonstrate the adaptation of a smartphone’s camera to function as a compact lensless microscope. Unlike other chip-scale microscopy schemes, this method uses ambient illumination as its light source and does not require the incorporation of a dedicated light source. The method is based on the shadow imaging technique where the sample is placed on the surface of the image sensor, which captures direct shadow images under illumination. To improve the imaging resolution beyond the pixel size, we perform pixel super-resolution reconstruction with multiple images at different angles of illumination, which are captured while the user is manually tilting the device around any ambient light source, such as the sun or a lamp. The lensless imaging scheme allows for sub-micron resolution imaging over an ultra-wide field-of-view (FOV). Image acquisition and reconstruction is performed on the device using a custom-built android application, constructing a stand-alone imaging device for field applications. We discuss the construction of the device using a commercial smartphone and demonstrate the imaging capabilities of our system. PMID:24964209

  12. A smartphone-based chip-scale microscope using ambient illumination.

    PubMed

    Lee, Seung Ah; Yang, Changhuei

    2014-08-21

    Portable chip-scale microscopy devices can potentially address various imaging needs in mobile healthcare and environmental monitoring. Here, we demonstrate the adaptation of a smartphone's camera to function as a compact lensless microscope. Unlike other chip-scale microscopy schemes, this method uses ambient illumination as its light source and does not require the incorporation of a dedicated light source. The method is based on the shadow imaging technique where the sample is placed on the surface of the image sensor, which captures direct shadow images under illumination. To improve the image resolution beyond the pixel size, we perform pixel super-resolution reconstruction with multiple images at different angles of illumination, which are captured while the user is manually tilting the device around any ambient light source, such as the sun or a lamp. The lensless imaging scheme allows for sub-micron resolution imaging over an ultra-wide field-of-view (FOV). Image acquisition and reconstruction are performed on the device using a custom-built Android application, constructing a stand-alone imaging device for field applications. We discuss the construction of the device using a commercial smartphone and demonstrate the imaging capabilities of our system. PMID:24964209

  13. DMD-based LED-illumination Super-resolution and optical sectioning microscopy

    PubMed Central

    Dan, Dan; Lei, Ming; Yao, Baoli; Wang, Wen; Winterhalder, Martin; Zumbusch, Andreas; Qi, Yujiao; Xia, Liang; Yan, Shaohui; Yang, Yanlong; Gao, Peng; Ye, Tong; Zhao, Wei

    2013-01-01

    Super-resolution three-dimensional (3D) optical microscopy has incomparable advantages over other high-resolution microscopic technologies, such as electron microscopy and atomic force microscopy, in the study of biological molecules, pathways and events in live cells and tissues. We present a novel approach of structured illumination microscopy (SIM) by using a digital micromirror device (DMD) for fringe projection and a low-coherence LED light for illumination. The lateral resolution of 90 nm and the optical sectioning depth of 120 μm were achieved. The maximum acquisition speed for 3D imaging in the optical sectioning mode was 1.6×107 pixels/second, which was mainly limited by the sensitivity and speed of the CCD camera. In contrast to other SIM techniques, the DMD-based LED-illumination SIM is cost-effective, ease of multi-wavelength switchable and speckle-noise-free. The 2D super-resolution and 3D optical sectioning modalities can be easily switched and applied to either fluorescent or non-fluorescent specimens. PMID:23346373

  14. A step-wise steerable source of illumination for low-noise "Violin-Mode" shadow sensors, intended for use in interferometric gravitational wave detectors.

    PubMed

    Lockerbie, N A; Tokmakov, K V

    2016-01-01

    A steerable low-noise source of illumination is described for shadow-sensors having a displacement sensitivity of ∼100 pm (rms)/√Hz, at 500 Hz, over a measuring span of at least ±0.5 mm. These sensors were designed to detect lateral "Violin-Mode" resonances in the highly tensioned fused-silica suspension fibres of the test-masses/mirrors for the Advanced Laser Interferometer Gravitational Wave Observatory gravitational wave detectors. The shadow sensors-one intended for each of the four fibres in a suspension-comprised a source of Near InfraRed (NIR) radiation (emitter) and a differential shadow-displacement sensor (detector), these bracketing the fibre under test. The suspension fibres themselves were approximately 600 mm long by 0.4 mm in diameter, and when illuminated from the side, they cast narrow, vertical, shadows onto their respective detectors-these being located at an effective distance of 50 fibre diameters behind the axes of the fibres themselves. The emitter described here was designed to compensate for a significant degree of mechanical drift or creep over time in the mean position of its suspension fibre. This was achieved by employing five adjacent columns of 8  × miniature NIR LEDs (Light Emitting Diodes, λ = 890 nm), with one column being activated at a time. When used in conjunction with a "reverse Galilean" telescope, the LED sources allowed the collimated beam from the emitter to be steered azimuthally in fine angular increments (0.65°), causing the fibre's shadow to move laterally, in a step-wise manner, across the plane of its facing detector. Each step in shadow position was approximately 0.23 mm in size, and this allowed the fibre's shadow to be re-centred, so as to bridge once again both elements of its photodiode detector-even if the fibre was off-centred by as much as ±0.5 mm. Re-centring allowed Violin-Mode vibrations of the fibre to be sensed once again as differential AC photocurrents, these flowing in anti-phase in the two

  15. Ambient illumination revisited: A new adaptation-based approach for optimizing medical imaging reading environments

    SciTech Connect

    Chawla, Amarpreet S.; Samei, Ehsan

    2007-01-15

    Ambient lighting in soft-copy reading rooms is currently kept at low values to preserve contrast rendition in the dark regions of a medical image. Low illuminance levels, however, create inadequate viewing conditions and may also cause eye strain. This eye strain may be potentially attributed to notable variations in the luminance adaptation state of the reader's eyes when moving the gaze intermittently between the brighter display and darker surrounding surfaces. This paper presents a methodology to minimize this variation and optimize the lighting conditions of reading rooms by exploiting the properties of liquid crystal displays (LCDs) with low diffuse reflection coefficients and high luminance ratio. First, a computational model was developed to determine a global luminance adaptation value, L{sub adp}, when viewing a medical image on display. The model is based on the diameter of the pupil size, which depends on the luminance of the observed object. Second, this value was compared with the luminance reflected off surrounding surfaces, L{sub s}, under various conditions of room illuminance, E, different values of diffuse reflection coefficients of surrounding surfaces, R{sub s}, and calibration settings of a typical LCD. The results suggest that for typical luminance settings of current LCDs, it is possible to raise ambient illumination to minimize differences in eye adaptation, potentially reducing visual fatigue while also complying with the TG18 specifications for controlled contrast rendition. Specifically, room illumination in the 75-150 lux range and surface diffuse reflection coefficients in the practical range of 0.13-0.22 sr{sup -1} provide an ideal setup for typical LCDs. Future LCDs with lower diffuse reflectivity and with higher inherent luminance ratios can provide further improvement of ergonomic viewing conditions in reading rooms.

  16. 77 FR 57083 - American Illuminating Company, LLC; Supplemental Notice that Initial Market-Based Rate Filing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission American Illuminating Company, LLC; Supplemental Notice that Initial Market... in the above-referenced proceeding, of American Illuminating Company, LLC's application for...

  17. Atomic Layer Deposition of Chemical Passivation Layers and High Performance Anti-Reflection Coatings on Back-Illuminated Detectors

    NASA Technical Reports Server (NTRS)

    Hoenk, Michael E. (Inventor); Greer, Frank (Inventor); Nikzad, Shouleh (Inventor)

    2014-01-01

    A back-illuminated silicon photodetector has a layer of Al2O3 deposited on a silicon oxide surface that receives electromagnetic radiation to be detected. The Al2O3 layer has an antireflection coating deposited thereon. The Al2O3 layer provides a chemically resistant separation layer between the silicon oxide surface and the antireflection coating. The Al2O3 layer is thin enough that it is optically innocuous. Under deep ultraviolet radiation, the silicon oxide layer and the antireflection coating do not interact chemically. In one embodiment, the silicon photodetector has a delta-doped layer near (within a few nanometers of) the silicon oxide surface. The Al2O3 layer is expected to provide similar protection for doped layers fabricated using other methods, such as MBE, ion implantation and CVD deposition.

  18. A step-wise steerable source of illumination for low-noise "Violin-Mode" shadow sensors, intended for use in interferometric gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Lockerbie, N. A.; Tokmakov, K. V.

    2016-01-01

    A steerable low-noise source of illumination is described for shadow-sensors having a displacement sensitivity of ˜100 pm (rms)/√Hz, at 500 Hz, over a measuring span of at least ±0.5 mm. These sensors were designed to detect lateral "Violin-Mode" resonances in the highly tensioned fused-silica suspension fibres of the test-masses/mirrors for the Advanced Laser Interferometer Gravitational Wave Observatory gravitational wave detectors. The shadow sensors—one intended for each of the four fibres in a suspension—comprised a source of Near InfraRed (NIR) radiation (emitter) and a differential shadow-displacement sensor (detector), these bracketing the fibre under test. The suspension fibres themselves were approximately 600 mm long by 0.4 mm in diameter, and when illuminated from the side, they cast narrow, vertical, shadows onto their respective detectors—these being located at an effective distance of 50 fibre diameters behind the axes of the fibres themselves. The emitter described here was designed to compensate for a significant degree of mechanical drift or creep over time in the mean position of its suspension fibre. This was achieved by employing five adjacent columns of 8 × miniature NIR LEDs (Light Emitting Diodes, λ = 890 nm), with one column being activated at a time. When used in conjunction with a "reverse Galilean" telescope, the LED sources allowed the collimated beam from the emitter to be steered azimuthally in fine angular increments (0.65°), causing the fibre's shadow to move laterally, in a step-wise manner, across the plane of its facing detector. Each step in shadow position was approximately 0.23 mm in size, and this allowed the fibre's shadow to be re-centred, so as to bridge once again both elements of its photodiode detector—even if the fibre was off-centred by as much as ±0.5 mm. Re-centring allowed Violin-Mode vibrations of the fibre to be sensed once again as differential AC photocurrents, these flowing in anti-phase in the

  19. Feasibility Study of EO SARs as Opportunity Illuminators in Passive Radars: PAZ-Based Case Study.

    PubMed

    Bárcena-Humanes, Jose-Luis; Gómez-Hoyo, Pedro-José; Jarabo-Amores, Maria-Pilar; Mata-Moya, David; Del-Rey-Maestre, Nerea

    2015-01-01

    Passive radars exploit the signal transmitted by other systems, known as opportunity illuminators (OIs), instead of using their own transmitter. Due to its almost total invulnerability to natural disasters or physical attacks, satellite OIs are of special interest. In this line, a feasibility study of Earth Observation Synthetic Aperture Radar (EO SAR) systems as OIs is carried out taking into consideration signal waveform, availability, bistatic geometry, instrumented coverage area and incident power density. A case study based on the use of PAZ, the first Spanish EO SAR, is presented. PAZ transmitted waveform, operation modes, orbit characteristics and antenna and transmitter parameters are analyzed to estimate potential coverages and resolutions. The study concludes that, due to its working in on-demand operating mode, passive radars based on PAZ-type illuminators can be proposed as complementing tools during the sensor commissioning phase, for system maintenance and for improving its performance by providing additional information about the area of interest and/or increasing the data updating speed, exploiting other sensors during the time PAZ is not available. PMID:26593921

  20. Feasibility Study of EO SARs as Opportunity Illuminators in Passive Radars: PAZ-Based Case Study

    PubMed Central

    Bárcena-Humanes, Jose-Luis; Gómez-Hoyo, Pedro-José; Jarabo-Amores, Maria-Pilar; Mata-Moya, David; De-Rey-Maestre, Nerea

    2015-01-01

    Passive radars exploit the signal transmitted by other systems, known as opportunity illuminators (OIs), instead of using their own transmitter. Due to its almost total invulnerability to natural disasters or physical attacks, satellite OIs are of special interest. In this line, a feasibility study of Earth Observation Synthetic Aperture Radar (EO SAR) systems as OIs is carried out taking into consideration signal waveform, availability, bistatic geometry, instrumented coverage area and incident power density. A case study based on the use of PAZ, the first Spanish EO SAR, is presented. PAZ transmitted waveform, operation modes, orbit characteristics and antenna and transmitter parameters are analyzed to estimate potential coverages and resolutions. The study concludes that, due to its working in on-demand operating mode, passive radars based on PAZ-type illuminators can be proposed as complementing tools during the sensor commissioning phase, for system maintenance and for improving its performance by providing additional information about the area of interest and/or increasing the data updating speed, exploiting other sensors during the time PAZ is not available. PMID:26593921

  1. Extinction-based shading and illumination in GPU volume ray-casting.

    PubMed

    Schlegel, Philipp; Makhinya, Maxim; Pajarola, Renato

    2011-12-01

    Direct volume rendering has become a popular method for visualizing volumetric datasets. Even though computers are continually getting faster, it remains a challenge to incorporate sophisticated illumination models into direct volume rendering while maintaining interactive frame rates. In this paper, we present a novel approach for advanced illumination in direct volume rendering based on GPU ray-casting. Our approach features directional soft shadows taking scattering into account, ambient occlusion and color bleeding effects while achieving very competitive frame rates. In particular, multiple dynamic lights and interactive transfer function changes are fully supported. Commonly, direct volume rendering is based on a very simplified discrete version of the original volume rendering integral, including the development of the original exponential extinction into a-blending. In contrast to a-blending forming a product when sampling along a ray, the original exponential extinction coefficient is an integral and its discretization a Riemann sum. The fact that it is a sum can cleverly be exploited to implement volume lighting effects, i.e. soft directional shadows, ambient occlusion and color bleeding. We will show how this can be achieved and how it can be implemented on the GPU. PMID:22034296

  2. Feature-specific imaging: Extensions to adaptive object recognition and active illumination based scene reconstruction

    NASA Astrophysics Data System (ADS)

    Baheti, Pawan K.

    Computational imaging (CI) systems are hybrid imagers in which the optical and post-processing sub-systems are jointly optimized to maximize the task-specific performance. In this dissertation we consider a form of CI system that measures the linear projections (i.e., features) of the scene optically, and it is commonly referred to as feature-specific imaging (FSI). Most of the previous work on FSI has been concerned with image reconstruction. Previous FSI techniques have also been non-adaptive and restricted to the use of ambient illumination. We consider two novel extensions of the FSI system in this work. We first present an adaptive feature-specific imaging (AFSI) system and consider its application to a face-recognition task. The proposed system makes use of previous measurements to adapt the projection basis at each step. We present both statistical and information-theoretic adaptation mechanisms for the AFSI system. The sequential hypothesis testing framework is used to determine the number of measurements required for achieving a specified misclassification probability. We demonstrate that AFSI system requires significantly fewer measurements than static-FSI (SFSI) and conventional imaging at low signal-to-noise ratio (SNR). We also show a trade-off, in terms of average detection time, between measurement SNR and adaptation advantage. Experimental results validating the AFSI system are presented. Next we present a FSI system based on the use of structured light. Feature measurements are obtained by projecting spatially structured illumination onto an object and collecting all of the reflected light onto a single photodetector. We refer to this system as feature-specific structured imaging (FSSI). Principal component features are used to define the illumination patterns. The optimal LMMSE operator is used to generate object estimates from the measurements. We demonstrate that this new imaging approach reduces imager complexity and provides improved image

  3. Quantification of the absorbed dose in 3D by means of advanced optical diagnostics based on structured illumination

    NASA Astrophysics Data System (ADS)

    Kristensson, Elias; Ceberg, Sofie; Bäck, Sven; Jordan, Kevin

    2015-01-01

    The purpose of this study was to present a novel optical diagnostic tool that corrects for undesired contribution of multiply scattered light, thus opening up for e.g. quantitative optical CT measurements of opaque samples. The approach is based on a technique called Structured Illumination (SI), which is commonly employed within microscopic imaging to enhance the depth-resolution. The concept of SI applies for many types of source-detector arrangements and the configuration employed in this paper relies on side-scattering detection. A nPAG polymer gel phantom was irradiated using 6 MV beam. Three-dimensional information was obtained by translating the sample perpendicular to the direction of light, thus sequentially probing different sections. These were then stacked together to form a 3D representation of the sample. By altering the polarization of the laser light during the data acquisition it was discovered that the aggregates responsible for the scattering of light followed Rayleigh scattering, implying that their individual sizes are smaller than, or in the order of, 500 nm.

  4. Influence of the illumination source on model-based SRAF placement

    NASA Astrophysics Data System (ADS)

    Gupta, Rachit; Dave, Aasutosh; Tejnil, Edita; Jayaram, Srividya; LaCour, Pat

    2011-04-01

    Sub-Resolution Assist Features (SRAFs) have been extensively used to improve the process margin for isolated and semi-isolated features. It has been shown that compared to rule-based SRAFs, model-based placement of SRAFs can result in better overall process window. Various model-based approaches have been reported to affect SRAF placements. Even with model-based solutions, the complexity of two-dimensional layouts results in SRAF placement conflicts, producing numerous challenges to optimal SRAF placement for each pattern configuration. Furthermore, tuning of SRAF placement algorithms becomes challenging with varying patterns and sources [1-3]. Recently, pixelated source in optical lithography has become the subject of increased exploration to enable 22/20 nm technology nodes and beyond. Optimization of the illumination shape, including free-form pixelated sources, has shown performance gains, compared to standard source shapes [4-6]. This paper will demonstrate the influence of such different free-form sources as well as conventional sources on model-based SRAF placement. Typically in source optimization, the selection of the optimization patterns is exigent since it drives the source solution. Small differences in the selected patterns produce subtle changes in the optimized source shapes. It has also been previously reported that SRAF placements are significantly dependent on the illumination [1]. In this paper, the impact of changes in the design and/or source optimization patterns on the optimized source and hence on the SRAF placement is reported. Variations in SRAF placements will be quantified as a function of change in the free-form sources. Lithographic performance of the different SRAF placement schema will be verified using simulation.

  5. High-responsivity vertical-illumination Si/Ge uni-traveling-carrier photodiodes based on silicon-on-insulator substrate

    PubMed Central

    Li, Chong; Xue, ChunLai; Liu, Zhi; Cong, Hui; Cheng, Buwen; Hu, Zonghai; Guo, Xia; Liu, Wuming

    2016-01-01

    Si/Ge uni-traveling carrier photodiodes exhibit higher output current when space-charge effect is overcome and the thermal effects is suppressed. High current is beneficial for increasing the dynamic range of various microwave photonic systems and simplifying high-bit-rate digital receivers in many applications. From the point of view of packaging, detectors with vertical-illumination configuration can be easily handled by pick-and-place tools and are a popular choice for making photo-receiver modules. However, vertical-illumination Si/Ge uni-traveling carrier (UTC) devices suffer from inter-constraint between high speed and high responsivity. Here, we report a high responsivity vertical-illumination Si/Ge UTC photodiode based on a silicon-on-insulator substrate. When the transmission of the monolayer anti-reflection coating was maximum, the maximum absorption efficiency of the devices was 1.45 times greater than the silicon substrate owing to constructive interference. The Si/Ge UTC photodiode had a dominant responsivity at 1550 nm of 0.18 A/W, a 50% improvement even with a 25% thinner Ge absorption layer. PMID:27279426

  6. High-responsivity vertical-illumination Si/Ge uni-traveling-carrier photodiodes based on silicon-on-insulator substrate

    NASA Astrophysics Data System (ADS)

    Li, Chong; Xue, Chunlai; Liu, Zhi; Cong, Hui; Cheng, Buwen; Hu, Zonghai; Guo, Xia; Liu, Wuming

    2016-06-01

    Si/Ge uni-traveling carrier photodiodes exhibit higher output current when space-charge effect is overcome and the thermal effects is suppressed. High current is beneficial for increasing the dynamic range of various microwave photonic systems and simplifying high-bit-rate digital receivers in many applications. From the point of view of packaging, detectors with vertical-illumination configuration can be easily handled by pick-and-place tools and are a popular choice for making photo-receiver modules. However, vertical-illumination Si/Ge uni-traveling carrier (UTC) devices suffer from inter-constraint between high speed and high responsivity. Here, we report a high responsivity vertical-illumination Si/Ge UTC photodiode based on a silicon-on-insulator substrate. When the transmission of the monolayer anti-reflection coating was maximum, the maximum absorption efficiency of the devices was 1.45 times greater than the silicon substrate owing to constructive interference. The Si/Ge UTC photodiode had a dominant responsivity at 1550 nm of 0.18 A/W, a 50% improvement even with a 25% thinner Ge absorption layer.

  7. High-responsivity vertical-illumination Si/Ge uni-traveling-carrier photodiodes based on silicon-on-insulator substrate.

    PubMed

    Li, Chong; Xue, ChunLai; Liu, Zhi; Cong, Hui; Cheng, Buwen; Hu, Zonghai; Guo, Xia; Liu, Wuming

    2016-01-01

    Si/Ge uni-traveling carrier photodiodes exhibit higher output current when space-charge effect is overcome and the thermal effects is suppressed. High current is beneficial for increasing the dynamic range of various microwave photonic systems and simplifying high-bit-rate digital receivers in many applications. From the point of view of packaging, detectors with vertical-illumination configuration can be easily handled by pick-and-place tools and are a popular choice for making photo-receiver modules. However, vertical-illumination Si/Ge uni-traveling carrier (UTC) devices suffer from inter-constraint between high speed and high responsivity. Here, we report a high responsivity vertical-illumination Si/Ge UTC photodiode based on a silicon-on-insulator substrate. When the transmission of the monolayer anti-reflection coating was maximum, the maximum absorption efficiency of the devices was 1.45 times greater than the silicon substrate owing to constructive interference. The Si/Ge UTC photodiode had a dominant responsivity at 1550 nm of 0.18 A/W, a 50% improvement even with a 25% thinner Ge absorption layer. PMID:27279426

  8. Deterministic phase retrieval employing spherical illumination

    NASA Astrophysics Data System (ADS)

    Martínez-Carranza, J.; Falaggis, K.; Kozacki, T.

    2015-05-01

    Deterministic Phase Retrieval techniques (DPRTs) employ a series of paraxial beam intensities in order to recover the phase of a complex field. These paraxial intensities are usually generated in systems that employ plane-wave illumination. This type of illumination allows a direct processing of the captured intensities with DPRTs for recovering the phase. Furthermore, it has been shown that intensities for DPRTs can be acquired from systems that use spherical illumination as well. However, this type of illumination presents a major setback for DPRTs: the captured intensities change their size for each position of the detector on the propagation axis. In order to apply the DPRTs, reescalation of the captured intensities has to be applied. This condition can increase the error sensitivity of the final phase result if it is not carried out properly. In this work, we introduce a novel system based on a Phase Light Modulator (PLM) for capturing the intensities when employing spherical illumination. The proposed optical system enables us to capture the diffraction pattern of under, in, and over-focus intensities. The employment of the PLM allows capturing the corresponding intensities without displacing the detector. Moreover, with the proposed optical system we can control accurately the magnification of the captured intensities. Thus, the stack of captured intensities can be used in DPRTs, overcoming the problems related with the resizing of the images. In order to prove our claims, the corresponding numerical experiments will be carried out. These simulations will show that the retrieved phases with spherical illumination are accurate and can be compared with those that employ plane wave illumination. We demonstrate that with the employment of the PLM, the proposed optical system has several advantages as: the optical system is compact, the beam size on the detector plane is controlled accurately, and the errors coming from mechanical motion can be suppressed easily.

  9. Compact ion chamber based neutron detector

    SciTech Connect

    Derzon, Mark S.; Galambos, Paul C.; Renzi, Ronald F.

    2015-10-27

    A directional neutron detector has an ion chamber formed in a dielectric material; a signal electrode and a ground electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; readout circuitry which is electrically coupled to the signal and ground electrodes; and a signal processor electrically coupled to the readout circuitry. The ion chamber has a pair of substantially planar electrode surfaces. The chamber pressure of the neutron absorbing material is selected such that the reaction particle ion trail length for neutrons absorbed by the neutron absorbing material is equal to or less than the distance between the electrode surfaces. The signal processor is adapted to determine a path angle for each absorbed neutron based on the rise time of the corresponding pulse in a time-varying detector signal.

  10. Monte Carlo model of a polychromatic laboratory based edge illumination x-ray phase contrast system.

    PubMed

    Millard, T P; Endrizzi, M; Diemoz, P C; Hagen, C K; Olivo, A

    2014-05-01

    A Monte Carlo model of a polychromatic laboratory based (coded aperture) edge illumination x-ray phase contrast imaging system has been developed and validated against experimental data. The ability for the simulation framework to be used to model two-dimensional images is also shown. The Monte Carlo model has been developed using the McXtrace engine and is polychromatic, i.e., results are obtained through the use of the full x-ray spectrum rather than an effective energy. This type of simulation can in future be used to model imaging of objects with complex geometry, for system prototyping, as well as providing a first step towards the development of a simulation for modelling dose delivery as a part of translating the imaging technique for use in clinical environments. PMID:24880377

  11. Colour-Based Binary Discrimination of Scarified Quercus robur Acorns under Varying Illumination.

    PubMed

    Jabłoński, Mirosław; Tylek, Paweł; Walczyk, Józef; Tadeusiewicz, Ryszard; Piłat, Adam

    2016-01-01

    Efforts to predict the germination ability of acorns using their shape, length, diameter and density are reported in the literature. These methods, however, are not efficient enough. As such, a visual assessment of the viability of seeds based on the appearance of cross-sections of seeds following their scarification is used. This procedure is more robust but demands significant effort from experienced employees over a short period of time. In this article an automated method of acorn scarification and assessment has been announced. This type of automation requires the specific setup of a machine vision system and application of image processing algorithms for evaluation of sections of seeds in order to predict their viability. In the stage of the analysis of pathological changes, it is important to point out image features that enable efficient classification of seeds in respect of viability. The article shows the results of the binary separation of seeds into two fractions (healthy or spoiled) using average components of regular red-green-blue and perception-based hue-saturation-value colour space. Analysis of accuracy of discrimination was performed on sections of 400 scarified acorns acquired using two various setups: machine vision camera under uncontrolled varying illumination and commodity high-resolution camera under controlled illumination. The accuracy of automatic classification has been compared with predictions completed by experienced professionals. It has been shown that both automatic and manual methods reach an accuracy level of 84%, assuming that the images of the sections are properly normalised. The achieved recognition ratio was higher when referenced to predictions provided by professionals. Results of discrimination by means of Bayes classifier have been also presented as a reference. PMID:27548173

  12. Illumination Under Trees

    SciTech Connect

    Max, N

    2002-08-19

    This paper is a survey of the author's work on illumination and shadows under trees, including the effects of sky illumination, sun penumbras, scattering in a misty atmosphere below the trees, and multiple scattering and transmission between leaves. It also describes a hierarchical image-based rendering method for trees.

  13. Ionization-based detectors for gas chromatography.

    PubMed

    Poole, Colin F

    2015-11-20

    The gas phase ionization detectors are the most widely used detectors for gas chromatography. The column and makeup gases commonly used in gas chromatography are near perfect insulators. This facilitates the detection of a minute number of charge carriers facilitating the use of ionization mechanisms of low efficiency while providing high sensitivity. The main ionization mechanism discussed in this report are combustion in a hydrogen diffusion flame (flame ionization detector), surface ionization in a plasma (thermionic ionization detector), photon ionization (photoionization detector and pulsed discharge helium ionization detector), attachment of thermal electrons (electron-capture detector), and ionization by collision with metastable helium species (helium ionization detector). The design, response characteristics, response mechanism, and suitability for fast gas chromatography are the main features summarized in this report. Mass spectrometric detection and atomic emission detection, which could be considered as ionization detectors of a more sophisticated and complex design, are not discussed in this report. PMID:25757823

  14. The design of color spectrophotometer based on diffuse illumination and compatible SCE/SCI geometric condition

    NASA Astrophysics Data System (ADS)

    Yuan, Kun; Yan, Hui-min; Jin, Shang-zhong

    2013-12-01

    The geometric conditions of diffuse illumination, 8 degree observation, specular light include (SCI) and specular light exclude (SCE) often be employed to measure the surface color of material with different gloss value. The SCE condition is usually realized by setting light trap on the integrating sphere. However, the structure of light trap has its negative influence on the light intensity uniformity, and can led to the inaccuracy of the test results under SCE or SCI condition. Due to the different sizes of the light trap, structures of the measurement instrument will led to inter instrument agreement among the measurement of sample with different gloss. This paper designs a measuring structure to measure the SCE and SCI results simultaneously; proposes a method to calculate the 8 degree gloss value based on the SCE and SCI test result; proposes a computing modal to modify the SCI and SCE measure result based on the 8 degree gloss value, experimental verifying is also carried out. The experimental results demonstrate the structure and modified model effectively reduce the negative influence of light trap. The inter instrument disagreement caused by the geometric dimension of different light trap is significantly decreased.

  15. Analysis of Cadmium Based Neutron Detector Configurations

    NASA Astrophysics Data System (ADS)

    James, Brian; Rees, Lawrence; Czirr, J. Bart

    2012-10-01

    Due to national security concerns pertaining to the smuggling of special nuclear materials and a small supply of He-3 for use in neutron detectors, there is currently a need for a new kind of neutron detector. Using Monte Carlo techniques I have studied the neutron capture efficiency of an array of cadmium wedge detectors in the presence of a californium source. By using varying numbers of wedges and comparing their capture ratios we will be better able to design future detectors.

  16. Coded illumination for motion-blur free imaging of cells on cell-phone based imaging flow cytometer

    NASA Astrophysics Data System (ADS)

    Saxena, Manish; Gorthi, Sai Siva

    2014-10-01

    Cell-phone based imaging flow cytometry can be realized by flowing cells through the microfluidic devices, and capturing their images with an optically enhanced camera of the cell-phone. Throughput in flow cytometers is usually enhanced by increasing the flow rate of cells. However, maximum frame rate of camera system limits the achievable flow rate. Beyond this, the images become highly blurred due to motion-smear. We propose to address this issue with coded illumination, which enables recovery of high-fidelity images of cells far beyond their motion-blur limit. This paper presents simulation results of deblurring the synthetically generated cell/bead images under such coded illumination.

  17. Photometric-based recovery of illuminant-free color images using a red-green-blue digital camera

    NASA Astrophysics Data System (ADS)

    Luis Nieves, Juan; Plata, Clara; Valero, Eva M.; Romero, Javier

    2012-01-01

    Albedo estimation has traditionally been used to make computational simulations of real objects under different conditions, but as yet no device is capable of measuring albedo directly. The aim of this work is to introduce a photometric-based color imaging framework that can estimate albedo and can reproduce the appearance both indoors and outdoors of images under different lights and illumination geometry. Using a calibration sample set composed of chips made of the same material but different colors and textures, we compare two photometric-stereo techniques, one of them avoiding the effect of shadows and highlights in the image and the other ignoring this constraint. We combined a photometric-stereo technique and a color-estimation algorithm that directly relates the camera sensor outputs with the albedo values. The proposed method can produce illuminant-free images with good color accuracy when a three-channel red-green-blue (RGB) digital camera is used, even outdoors under solar illumination.

  18. Hybridization of a sigma-delta-based CMOS hybrid detector

    NASA Astrophysics Data System (ADS)

    Kolb, K. E.; Stoffel, N. C.; Douglas, B.; Maloney, C. W.; Raisanen, A. D.; Ashe, B.; Figer, D. F.; Tamagawa, T.; Halpern, B.; Ignjatovic, Zeljko

    2010-07-01

    The Rochester Imaging Detector Laboratory, University of Rochester, Infotonics Technology Center, and Jet Process Corporation developed a hybrid silicon detector with an on-chip sigma-delta (ΣΔ) ADC. This paper describes the process and reports the results of developing a fabrication process to robustly produce high-quality bump bonds to hybridize a back-illuminated detector with its ΣΔ ADC. The design utilizes aluminum pads on both the readout circuit and the photodiode array with interconnecting indium bumps between them. The development of the bump bonding process is discussed, including specific material choices, interim process structures, and final functionality. Results include measurements of bond integrity, cross-wafer uniformity of indium bumps, and effects of process parameters on the final product. Future plans for improving the bump bonding process are summarized.

  19. Evaluation of expanded uncertainties in luminous intensity and illuminance calibrations

    SciTech Connect

    Sametoglu, Ferhat

    2008-11-01

    Detector-based calibrating methods and expressions for calculation of photometric uncertainties related to uncertainties in the calibrations of luminous intensity of a light source, illuminance responsivity of a photometer head, and calibration factors of an illuminance meter are discussed. These methods permit luminous intensity calibrations of incandescent light sources, luminous responsivity calibrations of photometer heads, and calibration factors of illuminance meters to be carried out with relative expanded uncertainties (with a level of confidence of 95.45%) of 0.4%, 0.4%, and 0.6%, respectively.

  20. A COMPARISON OF ILLUMINATION GEOMETRY-BASED METHODS FOR TOPOGRAPHIC CORRECTION OF QUICKBIRD IMAGES OF AN UNDULANT AREA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The high spatial resolution of QuickBird satellite images makes it possible to show spatial variability at fine details. However, the effect of topography-induced illumination variations become more evident, even in moderately sloped areas. Based on a high resolution (1 m) digital elevation model ge...

  1. Backside illuminated dye-sensitized solar cells based on titania nanotube array electrodes

    NASA Astrophysics Data System (ADS)

    Paulose, Maggie; Shankar, Karthik; Varghese, Oomman K.; Mor, Gopal K.; Hardin, Brian; Grimes, Craig A.

    2006-03-01

    Backside illuminated solar cells based on 6 µm long highly-ordered nanotube-array films sensitized by a self-assembled monolayer of bis(tetrabutylammonium)-cis-(dithiocyanato)- N,N'-bis(4-carboxylato-4'-carboxylic acid-2, 2'-bipyridine)ruthenium(II) (commonly called 'N719') show a short-circuit current density of 8.79 mA cm-2, 841 mV open circuit potential and a 0.57 fill factor yielding a power conversion efficiency of 4.24% under AM 1.5 sun. The solvent used to infiltrate the dye into the nanotube arrays, made by potentiostatic anodization of a titanium foil, was found to significantly influence the electrical characteristics of the resulting solar cell. A superior photoresponse was obtained with acetonitrile as the dye solvent. This is attributed to the improved wetting characteristics of the dye solution in acetonitrile enabling self-assembled monolayers with higher surface coverage to be formed inside the nanotubes. In comparison to nanocrystalline films, the nanotube-array films consistently exhibit larger open circuit photovoltage values; the origins of this enhancement are discussed.

  2. Performance comparisons of contour-based corner detectors.

    PubMed

    Awrangjeb, Mohammad; Lu, Guojun; Fraser, Clive S

    2012-09-01

    Corner detectors have many applications in computer vision and image identification and retrieval. Contour-based corner detectors directly or indirectly estimate a significance measure (e.g., curvature) on the points of a planar curve, and select the curvature extrema points as corners. While an extensive number of contour-based corner detectors have been proposed over the last four decades, there is no comparative study of recently proposed detectors. This paper is an attempt to fill this gap. The general framework of contour-based corner detection is presented, and two major issues-curve smoothing and curvature estimation, which have major impacts on the corner detection performance, are discussed. A number of promising detectors are compared using both automatic and manual evaluation systems on two large datasets. It is observed that while the detectors using indirect curvature estimation techniques are more robust, the detectors using direct curvature estimation techniques are faster. PMID:22645267

  3. Uncooled resonant infrared detector based on aluminum nitride piezoelectric film through charge generations and lattice absorptions

    NASA Astrophysics Data System (ADS)

    Ang, W. C.; Kropelnicki, P.; Zhu, Y.; Randles, A. B.; Gu, Y. A.; Leong, K. C.; Tan, C. S.

    2014-05-01

    This Letter demonstrates an aluminum nitride (AlN) based uncooled resonant infrared (IR) detector utilizing the photo-sensitive and piezoelectric properties of polycrystalline AlN. The AlN Lamb wave mode resonator is found responsive to IR illuminations by showing a decrease in the S21 magnitude instead of a resonant frequency shift. A -0.08 dB shift of S21 magnitude was observed for an IR incident power of 647 nW, which translates to a responsivity of 124 kdB/W. Photoresponse is proposed for the IR sensing mechanism through additional charge carriers generation rather than thermal effects.

  4. Depth resolved hyperspectral imaging spectrometer based on structured light illumination and Fourier transform interferometry.

    PubMed

    Choi, Heejin; Wadduwage, Dushan; Matsudaira, Paul T; So, Peter T C

    2014-10-01

    A depth resolved hyperspectral imaging spectrometer can provide depth resolved imaging both in the spatial and the spectral domain. Images acquired through a standard imaging Fourier transform spectrometer do not have the depth-resolution. By post processing the spectral cubes (x, y, λ) obtained through a Sagnac interferometer under uniform illumination and structured illumination, spectrally resolved images with depth resolution can be recovered using structured light illumination algorithms such as the HiLo method. The proposed scheme is validated with in vitro specimens including fluorescent solution and fluorescent beads with known spectra. The system is further demonstrated in quantifying spectra from 3D resolved features in biological specimens. The system has demonstrated depth resolution of 1.8 μm and spectral resolution of 7 nm respectively. PMID:25360367

  5. Depth resolved hyperspectral imaging spectrometer based on structured light illumination and Fourier transform interferometry

    PubMed Central

    Choi, Heejin; Wadduwage, Dushan; Matsudaira, Paul T.; So, Peter T.C.

    2014-01-01

    A depth resolved hyperspectral imaging spectrometer can provide depth resolved imaging both in the spatial and the spectral domain. Images acquired through a standard imaging Fourier transform spectrometer do not have the depth-resolution. By post processing the spectral cubes (x, y, λ) obtained through a Sagnac interferometer under uniform illumination and structured illumination, spectrally resolved images with depth resolution can be recovered using structured light illumination algorithms such as the HiLo method. The proposed scheme is validated with in vitro specimens including fluorescent solution and fluorescent beads with known spectra. The system is further demonstrated in quantifying spectra from 3D resolved features in biological specimens. The system has demonstrated depth resolution of 1.8 μm and spectral resolution of 7 nm respectively. PMID:25360367

  6. The biological significance of color constancy: an agent-based model with bees foraging from flowers under varied illumination.

    PubMed

    Faruq, Samia; McOwan, Peter W; Chittka, Lars

    2013-01-01

    The perceived color of an object depends on its spectral reflectance and the spectral composition of the illuminant. Thus when the illumination changes, the light reflected from the object also varies. This would result in a different color sensation if no color constancy mechanism is put in place-that is, the ability to form consistent representation of colors across various illuminants and background scenes. We explore the quantitative benefits of various color constancy algorithms in an agent-based model of foraging bees, where agents select flower color based on reward. Each simulation is based on 100 "meadows" with five randomly selected flower species with empirically determined spectral reflectance properties, and each flower species is associated with realistic distributions of nectar rewards. Simulated foraging bees memorize the colors of flowers that they have experienced as most rewarding, and their task is to discriminate against other flower colors with lower rewards, even in the face of changing illumination conditions. We compared the performance of von Kries, White Patch, and Gray World constancy models with (hypothetical) bees with perfect color constancy, and color-blind bees. A bee equipped with trichromatic color vision but no color constancy performed only ∼20% better than a color-blind bee (relative to a maximum improvement at 100% for perfect color constancy), whereas the most powerful recovery of reflectance in the face of changing illumination was generated by a combination of von Kries photoreceptor adaptation and a White Patch calibration (∼30% improvement relative to a bee without color constancy). However, none of the tested algorithms generated perfect color constancy. PMID:23962735

  7. LED lighting module design based on a prescribed candle-power distribution for uniform illumination

    NASA Astrophysics Data System (ADS)

    Chen, Jin-Jia; Huang, Kuang-Lung; Wang, Te-Yuan; Wang, Yi-Chih; Wang, Chuen-Ching; Guo, Tsung-Yi

    2010-11-01

    A simple approach is presented to design an LED lighting module to provide a uniform illumination. The reflector of the module is designed using a prescribed candle-power distribution to achieve a uniform illumination on a target surface. Both the design methodology and the construction of the reflector are stated in detail. The optical efficiency and uniformity of the module are calculated according to a ray-tracing result. In addition, the effects of the reflector's aperture and the LED chip size on the optical efficiency and uniformity are also investigated that the result can provide a reference to LED-luminaire designers and manufacturers.

  8. A laser beam shaper for homogeneous rectangular illumination based on freeform micro lens array

    NASA Astrophysics Data System (ADS)

    Chen, En-guo; Huang, Jia-min; Guo, Tai-liang; Wu, Reng-mao

    2016-07-01

    An effective design method of freeform micro lens array is presented for shaping varied laser beams into prescribed rectangular illumination. The variable separation mapping is applied to design concave freeform surfaces for constructing a freeform lens array. Several dedicated examples show that the designed freeform optical lens array can achieve a prescribed rectangular illumination pattern, especially without considering the initial states of incident laser beams. Both high collection efficiency and good spatial uniformity can be available simultaneously. Tolerance analysis is also performed to demonstrate that this optical device can well avoid fabricating difficulty in actual applications.

  9. A design of optical measurement laboratory for space-based illumination condition emulation

    NASA Astrophysics Data System (ADS)

    Xu, Rong; Zhao, Fei; Yang, Xin

    2015-10-01

    Space Objects Identification(SOI) and related technology have aroused wide attention from spacefaring nations due to the increasingly severe space environment. Multiple ground-based assets have been employed to acquire statistical survey data, detect faint debris, acquire photometric and spectroscopic data. Great efforts have been made to characterize different space objects using the statistical data acquired by telescopes. Furthermore, detailed laboratory data are needed to optimize the characterization of orbital debris and satellites via material composition and potential rotation axes, which calls for a high-precision and flexible optical measurement system. A typical method of taking optical measurements of a space object(or model) is to move light source and sensors through every possible orientation around it and keep the target still. However, moving equipments to accurate orientations in the air is difficult, especially for those large precise instruments sensitive to vibrations. Here, a rotation structure of "3+1" axes, with a three-axis turntable manipulating attitudes of the target and the sensor revolving around a single axis, is utilized to emulate every possible illumination condition in space, which can also avoid the inconvenience of moving large aparatus. Firstly, the source-target-sensor orientation of a real satellite was analyzed with vectors and coordinate systems built to illustrate their spatial relationship. By bending the Reference Coordinate Frame to the Phase Angle plane, the sensor only need to revolve around a single axis while the other three degrees of freedom(DOF) are associated with the Euler's angles of the satellite. Then according to practical engineering requirements, an integrated rotation system of four-axis structure is brought forward. Schemetic diagrams of the three-axis turntable and other equipments show an overview of the future laboratory layout. Finally, proposals on evironment arrangements, light source precautions

  10. OLED-based physiologically-friendly very low-color temperature illumination for night

    NASA Astrophysics Data System (ADS)

    Jou, Jwo-Huei; Shen, Shih-Ming; Tang, Ming-Chun; Chen, Pin-Chu; Chen, Szu-Hao; Wang, Yi-Shan; Chen, Chien-Chih; Wang, Ching-Chun; Hsieh, Chun-Yu; Lin, Chin-Chiao; Chen, Chien-Tien

    2012-09-01

    Numerous medical research studies reveal intense white or blue light to drastically suppress at night the secretion of melatonin (MLT), a protective oncostatic hormone. Lighting devices with lower color-temperature (CT) possess lesser MLT suppression effect based on the same luminance, explaining why physicians have long been calling for the development of lighting sources with low CT or free from blue emission for use at night to safeguard human health. We will demonstrate in the presentation the fabrication of OLED devices with very-low CT, especially those with CT much lower than that of incandescent bulbs (2500K) or even candles (2000K). Without any light extraction method, OLEDs with an around 1800K CT are easily obtainable with an efficacy of 30 lm/W at 1,000 nits. To also ensure high color-rendering to provide visual comfort, low CT OLEDs composing long wavelength dominant 5-spectrum emission have been fabricated. While keeping the color-rendering index as high as 85 and CT as low as 2100K, the resulting efficacy can also be much greater than that of incandescent bulbs (15 lm/W), proving these low CT OLED devices to be also capable of being energy-saving and high quality. The color-temperature can be further decreased to 1700K or lower upon removing the undesired short wavelength emission but on the cost of losing some color rendering index. It is hoped that the devised energy-saving, high quality low CT OLED could properly echo the call for a physiologically-friendly illumination for night, and more attention could be drawn to the development of MLT suppression-less non-white light.

  11. Illumination in diverse codimensions

    NASA Technical Reports Server (NTRS)

    Banks, David C.

    1994-01-01

    This paper derives a model of diffuse and specular illumination in arbitrarily large dimensions, based on a few characteristics of material and light in three-space. It then describes how to adjust for the anomaly of excess brightness in large codimensions. If a surface is grooved or furry, it can be illuminated with a hybrid model that incorporates both the one dimensional geometry (the grooves or fur) and the two dimensional geometry (the surface).

  12. PITBUL: a physics-based modeling package for imaging and tracking of airborne targets for HEL applications including active illumination

    NASA Astrophysics Data System (ADS)

    Van Zandt, Noah R.; McCrae, Jack E.; Fiorino, Steven T.

    2013-05-01

    Aimpoint acquisition and maintenance is critical to high energy laser (HEL) system performance. This study demonstrates the development by the AFIT/CDE of a physics-based modeling package, PITBUL, for tracking airborne targets for HEL applications, including atmospheric and sensor effects and active illumination, which is a focus of this work. High-resolution simulated imagery of the 3D airborne target in-flight as seen from the laser position is generated using the HELSEEM model, and includes solar illumination, laser illumination, and thermal emission. Both CW and pulsed laser illumination are modeled, including the effects of illuminator scintillation, atmospheric backscatter, and speckle, which are treated at a first-principles level. Realistic vertical profiles of molecular and aerosol absorption and scattering, as well as optical turbulence, are generated using AFIT/CDE's Laser Environmental Effects Definition and Reference (LEEDR) model. The spatially and temporally varying effects of turbulence are calculated and applied via a fast-running wave optical method known as light tunneling. Sensor effects, for example blur, sampling, read-out noise, and random photon arrival, are applied to the imagery. Track algorithms, including centroid and Fitts correlation, as a part of a closed loop tracker are applied to the degraded imagery and scored, to provide an estimate of overall system performance. To gauge performance of a laser system against a UAV target, tracking results are presented as a function of signal to noise ratio. Additionally, validation efforts to date involving comparisons between simulated and experimental tracking of UAVs are presented.

  13. A Comparison of the Perceptual Benefits of Linear Perspective and Physically-Based Illumination for Display of Dense 3D Streamtubes

    SciTech Connect

    Banks, David C

    2008-01-01

    Large datasets typically contain coarse features comprised of finer sub-features. Even if the shapes of the small structures are evident in a 3D display, the aggregate shapes they suggest may not be easily inferred. From previous studies in shape perception, the evidence has not been clear whether physically-based illumination confers any advantage over local illumination for understanding scenes that arise in visualization of large data sets that contain features at two distinct scales. In this paper we show that physically- based illumination can improve the perception for some static scenes of complex 3D geometry from flow fields. We perform human- subjects experiments to quantify the effect of physically-based illumination on participant performance for two tasks: selecting the closer of two streamtubes from a field of tubes, and identifying the shape of the domain of a flow field over different densities of tubes. We find that physically-based illumination influences participant performance as strongly as perspective projection, suggesting that physically-based illumination is indeed a strong cue to the layout of complex scenes. We also find that increasing the density of tubes for the shape identification task improved participant performance under physically-based illumination but not under the traditional hardware-accelerated illumination model.

  14. Fast 3D reconstruction of tool wear based on monocular vision and multi-color structured light illuminator

    NASA Astrophysics Data System (ADS)

    Wang, Zhongren; Li, Bo; Zhou, Yuebin

    2014-11-01

    Fast 3D reconstruction of tool wear from 2D images has great importance to 3D measuring and objective evaluating tool wear condition, determining accurate tool change and insuring machined part's quality. Extracting 3D information of tool wear zone based on monocular multi-color structured light can realize fast recovery of surface topography of tool wear, which overcomes the problems of traditional methods such as solution diversity and slow convergence when using SFS method and stereo match when using 3D reconstruction from multiple images. In this paper, a kind of new multi-color structured light illuminator was put forward. An information mapping model was established among illuminator's structure parameters, surface morphology and color images. The mathematical model to reconstruct 3D morphology based on monocular multi-color structured light was presented. Experimental results show that this method is effective and efficient to reconstruct the surface morphology of tool wear zone.

  15. Future of Semiconductor Based Thermal Neutron Detectors

    SciTech Connect

    Nikolic, R J; Cheung, C L; Reinhardt, C E; Wang, T F

    2006-02-22

    Thermal neutron detectors have seen only incremental improvements over the last decades. In this paper we overview the current technology of choice for thermal neutron detection--{sup 3}He tubes, which suffer from, moderate to poor fieldability, and low absolute efficiency. The need for improved neutron detection is evident due to this technology gap and the fact that neutrons are a highly specific indicator of fissile material. Recognizing this need, we propose to exploit recent advances in microfabrication technology for building the next generation of semiconductor thermal neutron detectors for national security requirements, for applications requiring excellent fieldability of small devices. We have developed an innovative pathway taking advantage of advanced processing and fabrication technology to produce the proposed device. The crucial advantage of our Pillar Detector is that it can simultaneously meet the requirements of high efficiency and fieldability in the optimized configuration, the detector efficiency could be higher than 70%.

  16. Neutron Detection with Water Cerenkov Based Detectors

    SciTech Connect

    Dazeley, S; Bernstein, A; Bowden, N; Carr, D; Ouedraogo, S; Svoboda, R; Sweany, M; Tripathi, M

    2009-05-13

    Legitimate cross border trade involves the transport of an enormous number of cargo containers. Especially following the September 11 attacks, it has become an international priority to verify that these containers are not transporting Special Nuclear Material (SNM) without impeding legitimate trade. Fission events from SNM produce a number of neutrons and MeV-scale gammas correlated in time. The observation of consistent time correlations between neutrons and gammas emitted from a cargo container could, therefore, constitute a robust signature for SNM, since this time coincident signature stands out strongly against the higher rate of uncorrelated gamma-ray backgrounds from the local environment. We are developing a cost effective way to build very large neutron detectors for this purpose. We have recently completed the construction of two new water Cherenkov detectors, a 250 liter prototype and a new 4 ton detector. We present both the results from our prototype detector and an update on the newly commissioned large detector. We will also present pictures from the construction and outline our future detector development plans.

  17. Image-based separation of reflective and fluorescent components using illumination variant and invariant color.

    PubMed

    Zhang, Cherry; Sato, Imari

    2013-12-01

    Traditionally, researchers tend to exclude fluorescence from color appearance algorithms in computer vision and image processing because of its complexity. In reality, fluorescence is a very common phenomenon observed in many objects, from gems and corals, to different kinds of writing paper, and to our clothes. In this paper, we provide detailed theories of fluorescence phenomenon. In particular, we show that the color appearance of fluorescence is unaffected by illumination in which it differs from ordinary reflectance. Moreover, we show that the color appearance of objects with reflective and fluorescent components can be represented as a linear combination of the two components. A linear model allows us to separate the two components using images taken under unknown illuminants using independent component analysis (ICA). The effectiveness of the proposed method is demonstrated using digital images of various fluorescent objects. PMID:24136427

  18. Memory operation devices based on light-illumination ambipolar carbon-nanotube thin-film-transistors

    SciTech Connect

    Aïssa, B.; Nedil, M.; Kroeger, J.; Haddad, T.; Rosei, F.

    2015-09-28

    We report the memory operation behavior of a light illumination ambipolar single-walled carbon nanotube thin film field-effect transistors devices. In addition to the high electronic-performance, such an on/off transistor-switching ratio of 10{sup 4} and an on-conductance of 18 μS, these memory devices have shown a high retention time of both hole and electron-trapping modes, reaching 2.8 × 10{sup 4} s at room temperature. The memory characteristics confirm that light illumination and electrical field can act as an independent programming/erasing operation method. This could be a fundamental step toward achieving high performance and stable operating nanoelectronic memory devices.

  19. A smartphone-based colorimetric reader for bioanalytical applications using the screen-based bottom illumination provided by gadgets.

    PubMed

    Vashist, Sandeep Kumar; van Oordt, Thomas; Schneider, E Marion; Zengerle, Roland; von Stetten, Felix; Luong, John H T

    2015-05-15

    A smartphone-based colorimetric reader (SBCR) was developed using a Samsung Galaxy SIII mini, a gadget (iPAD mini, iPAD4 or iPhone 5s), integrated with a custom-made dark hood and base holder assembly. The smartphone equipped with a back camera (5 megapixels resolution) was used for colorimetric imaging via the hood and base-holder assembly. A 96- or 24-well microtiter plate (MTP) was positioned on the gadget's screensaver that provides white light-based bottom illumination only in the specific regions corresponding to the bottom of MTP's wells. The pixel intensity of the captured images was determined by an image processing algorithm. The developed SBCR was evaluated and compared with a commercial MTP reader (MTPR) for three model assays: our recently developed human C-reactive protein sandwich enzyme-linked immunosorbent assay (ELISA), horseradish peroxidase direct ELISA, and bicinchoninic acid protein estimation assay. SBCR had the same precision, dynamic range, detection limit and sensitivity as MTPR for all three assays. With advanced microfabrication and data processing, SBCR will become more compact, lighter, inexpensive and enriched with more features. Therefore, SBCR with a remarkable computing power could be an ideal point-of-care (POC) colorimetric detection device for the next-generation of cost-effective POC diagnostics, immunoassays and diversified bioanalytical applications. PMID:25168283

  20. FBG-based sensorized light pipe for robotic intraocular illumination facilitates bimanual retinal microsurgery.

    PubMed

    Horise, Yuki; He, Xingchi; Gehlbach, Peter; Taylor, Russell; Iordachita, Iulian

    2015-01-01

    In retinal surgery, microsurgical instruments such as micro forceps, scissors and picks are inserted through the eye wall via sclerotomies. A handheld intraocular light source is typically used to visualize the tools during the procedure. Retinal surgery requires precise and stable tool maneuvers as the surgical targets are micro scale, fragile and critical to function. Retinal surgeons typically control an active surgical tool with one hand and an illumination source with the other. In this paper, we present a "smart" light pipe that enables true bimanual surgery via utilization of an active, robot-assisted source of targeted illumination. The novel sensorized smart light pipe measures the contact force between the sclerotomy and its own shaft, thereby accommodating the motion of the patient's eye. Forces at the point of contact with the sclera are detected by fiber Bragg grating (FBG) sensors on the light pipe. Our calibration and validation results demonstrate reliable measurement of the contact force as well as location of the sclerotomy. Preliminary experiments have been conducted to functionally evaluate robotic intraocular illumination. PMID:26736189

  1. Quantitative nanoimmunosensor based on dark-field illumination with enhanced sensitivity and on-off switching using scattering signals.

    PubMed

    Lee, Seungah; Nan, He; Yu, Hyunung; Kang, Seong Ho

    2016-05-15

    A nanoimmunosensor based on wavelength-dependent dark-field illumination with enhanced sensitivity was used to detect a disease-related protein molecule at zeptomolar (zM) concentrations. The assay platform of 100-nm gold nanospots could be selectively acquired using the wavelength-dependence of enhanced scattering signals from antibody-conjugated plasmonic silver nanoparticles (NPs) with on-off switching using optical filters. Detection of human thyroid-stimulating hormone (hTSH) at a sensitivity of 100 zM, which corresponds to 1-2 molecules per gold spot, was possible within a linear range of 100 zM-100 fM (R=0.9968). A significantly enhanced sensitivity (~4-fold) was achieved with enhanced dark-field illumination compared to using a total internal reflection fluorescence immunosensor. Immunoreactions were confirmed via optical axial-slicing based on the spectral characteristics of two plasmonic NPs. This method of using wavelength-dependent dark-field illumination had an enhanced sensitivity and a wide, linear dynamic range of 100 zM-100 fM, and was an effective tool for quantitatively detecting a single molecule on a nanobiochip for molecular diagnostics. PMID:26774086

  2. Three dimensional HiLo-based structured illumination for a digital scanned laser sheet microscopy (DSLM) in thick tissue imaging

    PubMed Central

    Bhattacharya, Dipanjan; Singh, Vijay Raj; Zhi, Chen; So, Peter T. C.; Matsudaira, Paul; Barbastathis, George

    2012-01-01

    Laser sheet based microscopy has become widely accepted as an effective active illumination method for real time three-dimensional (3D) imaging of biological tissue samples. The light sheet geometry, where the camera is oriented perpendicular to the sheet itself, provides an effective method of eliminating some of the scattered light and minimizing the sample exposure to radiation. However, residual background noise still remains, limiting the contrast and visibility of potentially interesting features in the samples. In this article, we investigate additional structuring of the illumination for improved background rejection, and propose a new technique, “3D HiLo” where we combine two HiLo images processed from orthogonal directions to improve the condition of the 3D reconstruction. We present a comparative study of conventional structured illumination based demodulation methods, namely 3Phase and HiLo with a newly implemented 3D HiLo approach and demonstrate that the latter yields superior signal-to-background ratio in both lateral and axial dimensions, while simultaneously suppressing image processing artifacts. PMID:23262684

  3. Radiation detector system having heat pipe based cooling

    DOEpatents

    Iwanczyk, Jan S.; Saveliev, Valeri D.; Barkan, Shaul

    2006-10-31

    A radiation detector system having a heat pipe based cooling. The radiation detector system includes a radiation detector thermally coupled to a thermo electric cooler (TEC). The TEC cools down the radiation detector, whereby heat is generated by the TEC. A heat removal device dissipates the heat generated by the TEC to surrounding environment. A heat pipe has a first end thermally coupled to the TEC to receive the heat generated by the TEC, and a second end thermally coupled to the heat removal device. The heat pipe transfers the heat generated by the TEC from the first end to the second end to be removed by the heat removal device.

  4. Novel infrared detector based on a tunneling displacement transducer

    NASA Technical Reports Server (NTRS)

    Kenny, T. W.; Kaiser, W. J.; Waltman, S. B.; Reynolds, J. K.

    1991-01-01

    The paper describes the design, fabrication, and characteristics of a novel infrared detector based on the principle of Golay's (1947) pneumatic infrared detector, which uses the expansion of a gas to detect infrared radiation. The present detector is constructed entirely from micromachined silicon and uses an electron tunneling displacement transducer for the detection of gas expansion. The sensitivity of the new detector is competitive with the best commercial pyroelectric sensors and can be readily improved by an order of magnitude through the use of an optimized transducer.

  5. Cyclotene diaphragm for MEMS based IR detectors

    NASA Astrophysics Data System (ADS)

    Guo, Shuwen

    2003-01-01

    A novel structure employing Dow Chemical (Midland, MI) benzocyclobutene (BCB) Cyclotene as a diaphragm material is presented in this report. The main advantages of this BCB diaphragm are its low thermal conductivity, robustness, chemical inertness, low curing temperature and high structure yield. Moreover, a BCB film can be either photo-defined or plasma etched and is a suitable micromachining material for post IC processing. Micromachined IR thermopile single detectors and lineal detector arrays (1×16), using BiSeTeSb/BiSbTe sensing elements on BCB diaphragms, have been constructed and tested. Up to 100% structure yield has been obtained. The process used to realize this detector structure is compatible with the eventual inclusion of on-chip circuitry for signal amplification and conditioning.

  6. Illuminating Development

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Through the support of the NASA SBIR program, Control Vision, Inc. developed novel video techniques for clear, high resolution, real-time imaging of high temperature, high-energy industrial processes, such as welding, plasma arc spraying (coating), arc furnaces, metal casting and refractories (ceramics) melting. The Control Vision systems use reflected laser or strobe illumination, combined with ultra-short exposure times to create video, including the allowance of particle imaging velocimetry (PIV) of fast moving powder particles buried within a plasma stream.

  7. Metamaterials for Cherenkov Radiation Based Particle Detectors

    SciTech Connect

    Tyukhtin, A. V.; Schoessow, P.; Kanareykin, A.; Antipov, S.

    2009-01-22

    Measurement of Cherenkov radiation (CR) has long been a useful technique for charged particle detection and beam diagnostics. We are investigating metamaterials engineered to have refractive indices tailored to enhance properties of CR that are useful for particle detectors and that cannot be obtained using conventional media. Cherenkov radiation in dispersive media with a large refractive index differs significantly from the same effect in conventional detector media, like gases or aerogel. The radiation pattern of CR in dispersive metamaterials presents lobes at very large angles with respect to particle motion. Moreover, the frequency and particle velocity dependence of the radiated energy can differ significantly from CR in a conventional dielectric medium.

  8. Hyperspectral venous image quality assessment for optimum illumination range selection based on skin tone characteristics

    PubMed Central

    2014-01-01

    Background Subcutaneous veins localization is usually performed manually by medical staff to find suitable vein to insert catheter for medication delivery or blood sample function. The rule of thumb is to find large and straight enough vein for the medication to flow inside of the selected blood vessel without any obstruction. The problem of peripheral difficult venous access arises when patient’s veins are not visible due to any reason like dark skin tone, presence of hair, high body fat or dehydrated condition, etc. Methods To enhance the visibility of veins, near infrared imaging systems is used to assist medical staff in veins localization process. Optimum illumination is crucial to obtain a better image contrast and quality, taking into consideration the limited power and space on portable imaging systems. In this work a hyperspectral image quality assessment is done to get the optimum range of illumination for venous imaging system. A database of hyperspectral images from 80 subjects has been created and subjects were divided in to four different classes on the basis of their skin tone. In this paper the results of hyper spectral image analyses are presented in function of the skin tone of patients. For each patient, four mean images were constructed by taking mean with a spectral span of 50 nm within near infrared range, i.e. 750–950 nm. Statistical quality measures were used to analyse these images. Conclusion It is concluded that the wavelength range of 800 to 850 nm serve as the optimum illumination range to get best near infrared venous image quality for each type of skin tone. PMID:25087016

  9. 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.

  10. Post-illumination pupil response after blue light: Reliability of optimized melanopsin-based phototransduction assessment.

    PubMed

    van der Meijden, Wisse P; te Lindert, Bart H W; Bijlenga, Denise; Coppens, Joris E; Gómez-Herrero, Germán; Bruijel, Jessica; Kooij, J J Sandra; Cajochen, Christian; Bourgin, Patrice; Van Someren, Eus J W

    2015-10-01

    Melanopsin-containing retinal ganglion cells have recently been shown highly relevant to the non-image forming effects of light, through their direct projections on brain circuits that regulate alertness, mood and circadian rhythms. A quantitative assessment of functionality of the melanopsin-signaling pathway could be highly relevant in order to mechanistically understand individual differences in the effects of light on these regulatory systems. We here propose and validate a reliable quantification of the melanopsin-dependent Post-Illumination Pupil Response (PIPR) after blue light, and evaluated its sensitivity to dark adaptation, time of day, body posture, and light exposure history. Pupil diameter of the left eye was continuously measured during a series of light exposures to the right eye, of which the pupil was dilated using tropicamide 0.5%. The light exposure paradigm consisted of the following five consecutive blocks of five minutes: baseline dark; monochromatic red light (peak wavelength: 630 nm, luminance: 375 cd/m(2)) to maximize the effect of subsequent blue light; dark; monochromatic blue light (peak wavelength: 470 nm, luminance: 375 cd/m(2)); and post-blue dark. PIPR was quantified as the difference between baseline dark pupil diameter and post-blue dark pupil diameter (PIPR-mm). In addition, a relative PIPR was calculated by dividing PIPR by baseline pupil diameter (PIPR-%). In total 54 PIPR assessments were obtained in 25 healthy young adults (10 males, mean age ± SD: 26.9 ± 4.0 yr). From repeated measurements on two consecutive days in 15 of the 25 participants (6 males, mean age ± SD: 27.8 ± 4.3 yrs) test-retest reliability of both PIPR outcome parameters was calculated. In the presence of considerable between-subject differences, both outcome parameters had very high test-retest reliability: Cronbach's α > 0.90 and Intraclass Correlation Coefficient > 0.85. In 12 of the 25 participants (6 males, mean age ± SD: 26.5

  11. EUV mirror based absolute incident flux detector

    DOEpatents

    Berger, Kurt W.

    2004-03-23

    A device for the in-situ monitoring of EUV radiation flux includes an integrated reflective multilayer stack. This device operates on the principle that a finite amount of in-band EUV radiation is transmitted through the entire multilayer stack. This device offers improvements over existing vacuum photo-detector devices since its calibration does not change with surface contamination.

  12. Detectors

    DOEpatents

    Orr, Christopher Henry; Luff, Craig Janson; Dockray, Thomas; Macarthur, Duncan Whittemore; Bounds, John Alan; Allander, Krag

    2002-01-01

    The apparatus and method provide techniques through which both alpha and beta emission determinations can be made simultaneously using a simple detector structure. The technique uses a beta detector covered in an electrically conducting material, the electrically conducting material discharging ions generated by alpha emissions, and as a consequence providing a measure of those alpha emissions. The technique also offers improved mountings for alpha detectors and other forms of detectors against vibration and the consequential effects vibration has on measurement accuracy.

  13. The performance of 2D array detectors for light sheet based fluorescence correlation spectroscopy.

    PubMed

    Singh, Anand Pratap; Krieger, Jan Wolfgang; Buchholz, Jan; Charbon, Edoardo; Langowski, Jörg; Wohland, Thorsten

    2013-04-01

    Single plane illumination microscopy based fluorescence correlation spectroscopy (SPIM-FCS) is a new method for imaging FCS in 3D samples, providing diffusion coefficients, transport, flow velocities and concentrations in an imaging mode. SPIM-FCS records correlation functions over a whole plane in a sample, which requires array detectors for recording the fluorescence signal. Several types of image sensors are suitable for FCS. They differ in properties such as effective area per pixel, quantum efficiency, noise level and read-out speed. Here we compare the performance of several low light array detectors based on three different technologies: (1) Single-photon avalanche diode (SPAD) arrays, (2) passive-pixel electron multiplying charge coupled device (EMCCD) and (3) active-pixel scientific-grade complementary metal oxide semiconductor cameras (sCMOS). We discuss the influence of the detector characteristics on the effective FCS observation volume, and demonstrate that light sheet based SPIM-FCS provides absolute diffusion coefficients. This is verified by parallel measurements with confocal FCS, single particle tracking (SPT), and the determination of concentration gradients in space and time. While EMCCD cameras have a temporal resolution in the millisecond range, sCMOS cameras and SPAD arrays can extend the time resolution of SPIM-FCS down to 10 μs or lower. PMID:23571955

  14. Radioiodine detector based on laser induced fluorescence

    DOEpatents

    McDonald, Jimmie R.; Baronavski, Andrew P.

    1980-01-01

    The invention involves the measurement of the concentration of the radioisotope .sup.129 I.sub.2 in the presence of a gas. The invention uses a laser to excite a sample of the .sup.129 I.sub.2 in a sample gas chamber and a reference sample of a known concentration of .sup.129 I.sub.2 in a reference gas chamber. The .sup.129 I.sub.2 in the sample and reference gas chamber each gives off fluorescence emissions which are received by photomultipliers which provide signals to a detector. The detector uses a ratioing technique to determine the concentration of .sup.129 I.sub.2 in the sample gas chamber.

  15. Polyaniline-based optical ammonia detector

    DOEpatents

    Duan, Yixiang; Jin, Zhe; Su, Yongxuan

    2002-01-01

    Electronic absorption spectroscopy of a polyaniline film deposited on a polyethylene surface by chemical oxidation of aniline monomer at room temperature was used to quantitatively detect ammonia gas. The present optical ammonia gas detector was found to have a response time of less than 15 s, a regeneration time of less than 2 min. at room temperature, and a detection limit of 1 ppm (v/v) for ammonia, with a linear dynamic range from 180 ppm to 18,000 ppm.

  16. Analysis of laser jamming to satellite-based detector

    NASA Astrophysics Data System (ADS)

    Wang, Si-wen; Guo, Li-hong; Guo, Ru-hai

    2009-07-01

    The reconnaissance satellite, communication satellite and navigation satellite used in the military applications have played more and more important role in the advanced technique wars and already become the significant support and aid system for military actions. With the development of all kinds of satellites, anti-satellite laser weapons emerge as the times require. The experiments and analyses of laser disturbing CCD (charge coupled detector) in near ground have been studied by many research groups, but their results are not suitable to the case that using laser disturbs the satellite-based detector. Because the distance between the satellite-based detector and the ground is very large, it is difficult to damage it directly. However the optical receive system of satellite detector has large optical gain, so laser disturbing satellite detector is possible. In order to determine its feasibility, the theoretical analyses and experimental study are carried out in the paper. Firstly, the influence factors of laser disturbing satellite detector are analyzed in detail, which including laser power density on the surface of the detector after long distance transmission, and laser power density threshold for disturbing etc. These factors are not only induced by the satellite orbit, but dependence on the following parameters: laser average power in the ground, laser beam quality, tracing and aiming precision and atmospheric transmission. A calculation model is developed by considering all factors which then the power density entering into the detector can be calculated. Secondly, the laser disturbing experiment is performed by using LD (laser diode) with the wavelength 808 nm disturbing CCD 5 kilometer away, which the disturbing threshold value is obtained as 3.55×10-4mW/cm2 that coincides with other researcher's results. Finally, using the theoretical model, the energy density of laser on the photosensitive surface of MSTI-3 satellite detector is estimated as about 100m

  17. A Passive FPAA-Based RF Scatter Meteor Detector

    NASA Astrophysics Data System (ADS)

    Popowicz, A.; Malcher, A.; Bernacki, K.; Fietkiewicz, K.

    2015-02-01

    In the article, we present a hardware meteor detector. The detection principle is based on the electromagnetic wave reflection from the ionized meteor trail in the atmosphere. The detector uses the ANADIGM field programmable analog array (FPAA), which is an attractive alternative for typically used detecting equipment—a PC computer with dedicated software. We implement an analog signal path using most of available FPAA resources to obtain precise audio signal detection. Our new detector was verified in collaboration with the Polish Fireball Network, the organization which monitors meteor activity in Poland. When compared with currently used signal processing PC software employing real radio meteor scatter signals, our low-cost detector proved to be more precise and reliable. Due to its cost and efficiency superiority over the current solution, the presented module is going to be implemented in the planned distributed detectors system.

  18. Room temperature particle detectors based on indium phosphide

    NASA Astrophysics Data System (ADS)

    Yatskiv, R.; Grym, J.; Zdansky, K.; Pekarek, L.

    2010-01-01

    A study of electrical properties and detection performance of particle detectors based on bulk InP and semiconducting LPE layers operated at room temperature is presented. Bulk detectors were fabricated on semi-insulating InP crystals grown by liquid-encapsulated Czochralski (LEC) technique. High purity InP layers of both n- and p-type conductivity were used to fabricate detector structures with p-n junction. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature. Better noise properties were achieved for detectors with p-n junctions due to better quality contacts on p-type layers.

  19. Preceding vehicle detection and tracking adaptive to illumination variation in night traffic scenes based on relevance analysis.

    PubMed

    Guo, Junbin; Wang, Jianqiang; Guo, Xiaosong; Yu, Chuanqiang; Sun, Xiaoyan

    2014-01-01

    Preceding vehicle detection and tracking at nighttime are challenging problems due to the disturbance of other extraneous illuminant sources coexisting with the vehicle lights. To improve the detection accuracy and robustness of vehicle detection, a novel method for vehicle detection and tracking at nighttime is proposed in this paper. The characteristics of taillights in the gray level are applied to determine the lower boundary of the threshold for taillights segmentation, and the optimal threshold for taillight segmentation is calculated using the OTSU algorithm between the lower boundary and the highest grayscale of the region of interest. The candidate taillight pairs are extracted based on the similarity between left and right taillights, and the non-vehicle taillight pairs are removed based on the relevance analysis of vehicle location between frames. To reduce the false negative rate of vehicle detection, a vehicle tracking method based on taillights estimation is applied. The taillight spot candidate is sought in the region predicted by Kalman filtering, and the disturbed taillight is estimated based on the symmetry and location of the other taillight of the same vehicle. Vehicle tracking is completed after estimating its location according to the two taillight spots. The results of experiments on a vehicle platform indicate that the proposed method could detect vehicles quickly, correctly and robustly in the actual traffic environments with illumination variation. PMID:25195855

  20. Preceding Vehicle Detection and Tracking Adaptive to Illumination Variation in Night Traffic Scenes Based on Relevance Analysis

    PubMed Central

    Guo, Junbin; Wang, Jianqiang; Guo, Xiaosong; Yu, Chuanqiang; Sun, Xiaoyan

    2014-01-01

    Preceding vehicle detection and tracking at nighttime are challenging problems due to the disturbance of other extraneous illuminant sources coexisting with the vehicle lights. To improve the detection accuracy and robustness of vehicle detection, a novel method for vehicle detection and tracking at nighttime is proposed in this paper. The characteristics of taillights in the gray level are applied to determine the lower boundary of the threshold for taillights segmentation, and the optimal threshold for taillight segmentation is calculated using the OTSU algorithm between the lower boundary and the highest grayscale of the region of interest. The candidate taillight pairs are extracted based on the similarity between left and right taillights, and the non-vehicle taillight pairs are removed based on the relevance analysis of vehicle location between frames. To reduce the false negative rate of vehicle detection, a vehicle tracking method based on taillights estimation is applied. The taillight spot candidate is sought in the region predicted by Kalman filtering, and the disturbed taillight is estimated based on the symmetry and location of the other taillight of the same vehicle. Vehicle tracking is completed after estimating its location according to the two taillight spots. The results of experiments on a vehicle platform indicate that the proposed method could detect vehicles quickly, correctly and robustly in the actual traffic environments with illumination variation. PMID:25195855

  1. Vineyard Yield Estimation Based on the Analysis of High Resolution Images Obtained with Artificial Illumination at Night

    PubMed Central

    Font, Davinia; Tresanchez, Marcel; Martínez, Dani; Moreno, Javier; Clotet, Eduard; Palacín, Jordi

    2015-01-01

    This paper presents a method for vineyard yield estimation based on the analysis of high-resolution images obtained with artificial illumination at night. First, this paper assesses different pixel-based segmentation methods in order to detect reddish grapes: threshold based, Mahalanobis distance, Bayesian classifier, linear color model segmentation and histogram segmentation, in order to obtain the best estimation of the area of the clusters of grapes in this illumination conditions. The color spaces tested were the original RGB and the Hue-Saturation-Value (HSV). The best segmentation method in the case of a non-occluded reddish table-grape variety was the threshold segmentation applied to the H layer, with an estimation error in the area of 13.55%, improved up to 10.01% by morphological filtering. Secondly, after segmentation, two procedures for yield estimation based on a previous calibration procedure have been proposed: (1) the number of pixels corresponding to a cluster of grapes is computed and converted directly into a yield estimate; and (2) the area of a cluster of grapes is converted into a volume by means of a solid of revolution, and this volume is converted into a yield estimate; the yield errors obtained were 16% and −17%, respectively. PMID:25860071

  2. Vineyard yield estimation based on the analysis of high resolution images obtained with artificial illumination at night.

    PubMed

    Font, Davinia; Tresanchez, Marcel; Martínez, Dani; Moreno, Javier; Clotet, Eduard; Palacín, Jordi

    2015-01-01

    This paper presents a method for vineyard yield estimation based on the analysis of high-resolution images obtained with artificial illumination at night. First, this paper assesses different pixel-based segmentation methods in order to detect reddish grapes: threshold based, Mahalanobis distance, Bayesian classifier, linear color model segmentation and histogram segmentation, in order to obtain the best estimation of the area of the clusters of grapes in this illumination conditions. The color spaces tested were the original RGB and the Hue-Saturation-Value (HSV). The best segmentation method in the case of a non-occluded reddish table-grape variety was the threshold segmentation applied to the H layer, with an estimation error in the area of 13.55%, improved up to 10.01% by morphological filtering. Secondly, after segmentation, two procedures for yield estimation based on a previous calibration procedure have been proposed: (1) the number of pixels corresponding to a cluster of grapes is computed and converted directly into a yield estimate; and (2) the area of a cluster of grapes is converted into a volume by means of a solid of revolution, and this volume is converted into a yield estimate; the yield errors obtained were 16% and -17%, respectively. PMID:25860071

  3. Special Nuclear Material Detection with a Water Cherenkov based Detector

    SciTech Connect

    Sweany, M; Bernstein, A; Bowden, N; Dazeley, S; Svoboda, R

    2008-11-10

    Fission events from Special Nuclear Material (SNM), such as highly enriched uranium or plutonium, produce a number of neutrons and high energy gamma-rays. Assuming the neutron multiplicity is approximately Poissonian with an average of 2 to 3, the observation of time correlations between these particles from a cargo container would constitute a robust signature of the presence of SNM inside. However, in order to be sensitive to the multiplicity, one would require a high total efficiency. There are two approaches to maximize the total efficiency; maximizing the detector efficiency or maximizing the detector solid angle coverage. The advanced detector group at LLNL is investigating one way to maximize the detector size. We are designing and building a water Cerenkov based gamma and neutron detector for the purpose of developing an efficient and cost effective way to deploy a large solid angle car wash style detector. We report on our progress in constructing a larger detector and also present preliminary results from our prototype detector that indicates detection of neutrons.

  4. Diffraction measurements with a boron-based GEM neutron detector

    NASA Astrophysics Data System (ADS)

    Croci, Gabriele; Albani, Giorgia; Cazzaniga, Carlo; Perelli Cippo, Enrico; Schooneveld, Erik; Claps, Gerardo; Cremona, Anna; Grosso, Giovanni; Muraro, Andrea; Murtas, Fabrizio; Rebai, Marica; Scherillo, Antonella; Tardocchi, Marco; Gorini, Giuseppe

    2014-07-01

    The research of reliable substitutes of 3He detectors is an important task for the affordability of new neutron scattering instrumentation for future spallation sources like the European Spallation Source. GEM (Gas Electron Multiplier)-based detectors represent a valid alternative since they can combine high-rate capability, coverage of up to 1\\ \\text{m}^{2} area and good intrinsic spatial resolution (for this detector class it can be better than 0.5 mm). The first neutron diffraction measurements performed using a borated GEM detector are reported. The detector has an active area of 10 \\times 5\\ \\text{cm}^{2} and is equipped with a borated cathode. The GEM detector was read out using the standard ISIS Data Acquisition System. The comparison with measurements performed with standard 3He detectors shows that the broadening of the peaks measured on the diffractogram obtained with the GEM is 20-30% wider than the one obtained by 3He tubes but the active area of the GEM is twice that of 3He tubes. The GEM resolution is improved if half of its active area is considered. The signal-to-background ratio of the GEM is about 1.5 to 2 times lower than that of 3He. This measurement proves that GEM detectors can be used for neutron diffraction measurements and paves the way for their use at future neutron spallation sources.

  5. Epithermal Neutrons, Illumination, Spatial Scale and Topography: A Correlative Analysis of Factors Influencing the Detection of Slope Hydration Using LRO's Lunar Exploration Neutron Detector

    NASA Astrophysics Data System (ADS)

    McClanahan, T. P.; Mitrofanov, I. G.; Boynton, W. V.; Chin, G.; Evans, L. G.; Starr, R. D.; Livengood, T.; Sagdeev, R.; Parsons, A. M.; Su, J. J.; Murray, J.; Sanin, A.; Litvak, M.; Harshman, K.; Hamara, D.; Bodnarik, J.

    2014-10-01

    This research correlates the Moon’s south polar epithermal neutron flux, topography and a visible illumination model and shows that there is a widespread hydration of polward-facing (PF) slopes that is occurring at a continuum of spatial scales.

  6. Evaluation of a photon-counting x-ray imaging detector based on microchannel plates for mammography applications

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.; Xu, Tong; Molloi, Sabee

    2004-05-01

    Experimental prototype of a photon counting scanning slit X-ray imaging system is being evaluated for potential application in digital mammography. This system is based on a recently developed and tested "edge-on" illuminated Microchannel Plate (MCP) detector. The MCP detectors are well known for providing a combination of capabilities such as direct conversion, physical charge amplification, pulse counting, high spatial and temporal resolution, and very low noise. However, their application for medical imaging was hampered by their low detection efficiency. This limitation was addressed using an "edge-on" illumination mode for MCP. The current experimental prototype was developed to investigate the imaging performance of this detector concept for digital mammography. The current prototype provides a 60 mm field of view, 200 kHz count rate with 20% non-paralysable dead time and >7 lp/mm limiting resolution. A 0.3 mm focal spot W target X-ray tube was used for image acquisition. The detector noise is 0.3 count/pixel for 50x50 micron pixels. The count rate of the current prototype is limited by the delay line readout electronics, which causes long scanning times (minutes) and high tube loading. This problem will be addressed using multichannel ASIC electronics for clinical implementation. However, the current readout architecture is adequate for evaluation of the performance parameters of the new detector concept. It is very simple and provides a maximum intrinsic resolution of 28 micron FWHM. The prototype was evaluated using resolution, contrast detail and breast Phantoms. The MTF and DQE of the system are being evaluated at different tube voltages. The design parameters of a scanning multiple slit mammography system are being evaluated. It is concluded that a photon counting, quantum limited and virtually scatter free digital mammography system can be developed based on the proposed detector.

  7. Selective detector of cosmic particles based on diamond sensitive elements

    NASA Astrophysics Data System (ADS)

    Altukhov, A. A.; Zaharchenko, K. V.; Kolyubin, V. A.; Lvov, S. A.; Nedosekin, P. G.; Tyurin, E. M.; Ibragimov, R. F.; Kadilin, V. V.; Nikolaev, I. V.

    2016-02-01

    The article describes the device for selective registration of electrons, protons and heavy ions fluxes from the solar and galactic cosmic rays in the twelve energy ranges, built on a base of diamond detector. The use of the diamond detectors allowed for the creation a device for registration of cosmic particles fluxes at the external spacecraft surface with the resource not less than 20 years. Selective detector is aimed for continuous monitoring of radiation situation on board the spacecrafts, in order to predict the residual life of their work and prompt measures to actively protect the spacecraft when the flow of cosmic particles is sharply increased.

  8. Development of video processing based on coal flame detector system

    SciTech Connect

    He Wanqing; Yu Yuefeng; Xu Weiyong; Ma Liqun

    1999-07-01

    The principle and development of a set of pulverized coal combustion flame detection system, which is called intelligent image flame detector device based on digital video processing, is addressed in this paper. The system realizes multi-burner flame detection and processing using a distributive structure of engineering workstation and flame detectors via multi-serial-port communication. The software can deal with multi-tasks in a parallel way based on multi-thread mechanism. Streaming video capture and storage is provided to safe and playback the accidental Audio and Visual Interfaces (AVI) clips. The layer flame detectors can give the flame on/off signal through image processing. Pseudo-color visualization of flame temperature calculated from chromatic CCD signal is integrated into the system. The image flame detector system has been successfully used in thermal power generation units in China.

  9. UV-laser-based longitudinal illuminated diffuser (LID) incorporating diffractive and Lambertian reflectance for the disinfection of beverages

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd

    2010-08-01

    A novel laser beam shaping system was designed to demonstrate the potential of using high power UV laser sources for large scale disinfection of liquids used in the production of food products, such as juices, beer, milk and other beverage types. The design incorporates a patented assembly of optical components including a diffractive beam splitting/shaping element and a faceted pyramidal or conically shaped Lambertian diffuser made from a compression molded PTFE compounds. When properly sintered to an appropriate density, as an example between 1.10 and 1.40 grams per cubic centimeter, the compressed PTFE compounds show a ~99% reflectance at wavelengths ranging from 300 nm to 1500 nm, and a ~98.5% refection of wavelengths from 250 nm to 2000 nm [1]. The unique diffuser configuration also benefits from the fact that the PTFE compounds do not degrade when exposed to ultraviolet radiation as do barium sulfate materials and silver or aluminized mirror coatings [2]. These components are contained within a hermetically sealed quartz tube. Once assembled a laser beam is directed through one end of the tube. This window takes the form of a computer generated diffractive splitter or other diffractive shaper element to split the laser beam into a series of spot beamlets, circular rings or other geometric shapes. As each of the split beamlets or rings cascade downward, they illuminate various points along the tapered PTFE cone or faceted pyramidal form. As they strike the surface they each diffuse in a Lambertian reflectance pattern creating a pseudo-uniform circumferential illuminator along the length of the quartz tube enclosing the assembly. The compact tubular structure termed Longitudinal Illuminated Diffuser (LID) provides a unique UV disinfection source that can be placed within a centrifugal reactor or a pipe based reactor chamber. This paper will review the overall design principle, key component design parameters, preliminary analytic and bench operational testing

  10. Needle-based fluorescence endomicroscopy via structured illumination with a plastic, achromatic objective

    PubMed Central

    Kyrish, Matthew; Dobbs, Jessica; Jain, Shalini; Wang, Xiao; Yu, Dihua; Richards-Kortum, Rebecca

    2013-01-01

    Abstract. In order to diagnose cancer, a sample must be removed, prepared, and examined under a microscope, which is expensive, invasive, and time consuming. Fiber optic fluorescence endomicroscopy, where an image guide is used to obtain high-resolution images of tissue in vivo, has shown promise as an alternative to conventional biopsies. However, the resolution of standard endomicroscopy is limited by the fiber bundle sampling frequency and out-of-focus light. A system is presented which incorporates a plastic, achromatic objective to increase the sampling and which provides optical sectioning via structured illumination to reject background light. An image is relayed from the sample by a fiber bundle with the custom 2.1-mm outer diameter objective lens integrated to the distal tip. The objective is corrected for the excitation and the emission wavelengths of proflavine (452 and 515 nm). It magnifies the object onto the fiber bundle to improve the system’s lateral resolution by increasing the sampling. The plastic lenses were fabricated via single-point diamond turning and assembled using a zero alignment technique. Ex vivo images of normal and neoplastic murine mammary tissues stained with proflavine are captured. The system achieves higher contrast and resolves smaller features than standard fluorescence endomicroscopy. PMID:24002190

  11. Time-lapse contact microscopy of cell cultures based on non-coherent illumination

    PubMed Central

    Gabriel, Marion; Balle, Dorothée; Bigault, Stéphanie; Pornin, Cyrille; Gétin, Stéphane; Perraut, François; Block, Marc R.; Chatelain, François; Picollet-D’hahan, Nathalie; Gidrol, Xavier; Haguet, Vincent

    2015-01-01

    Video microscopy offers outstanding capabilities to investigate the dynamics of biological and pathological mechanisms in optimal culture conditions. Contact imaging is one of the simplest imaging architectures to digitally record images of cells due to the absence of any objective between the sample and the image sensor. However, in the framework of in-line holography, other optical components, e.g., an optical filter or a pinhole, are placed underneath the light source in order to illuminate the cells with a coherent or quasi-coherent incident light. In this study, we demonstrate that contact imaging with an incident light of both limited temporal and spatial coherences can be achieved with sufficiently high quality for most applications in cell biology, including monitoring of cell sedimentation, rolling, adhesion, spreading, proliferation, motility, death and detachment. Patterns of cells were recorded at various distances between 0 and 1000 μm from the pixel array of the image sensors. Cells in suspension, just deposited or at mitosis focalise light into photonic nanojets which can be visualised by contact imaging. Light refraction by cells significantly varies during the adhesion process, the cell cycle and among the cell population in connection with every modification in the tridimensional morphology of a cell. PMID:26459014

  12. Time-lapse contact microscopy of cell cultures based on non-coherent illumination.

    PubMed

    Gabriel, Marion; Balle, Dorothée; Bigault, Stéphanie; Pornin, Cyrille; Gétin, Stéphane; Perraut, François; Block, Marc R; Chatelain, François; Picollet-D'hahan, Nathalie; Gidrol, Xavier; Haguet, Vincent

    2015-01-01

    Video microscopy offers outstanding capabilities to investigate the dynamics of biological and pathological mechanisms in optimal culture conditions. Contact imaging is one of the simplest imaging architectures to digitally record images of cells due to the absence of any objective between the sample and the image sensor. However, in the framework of in-line holography, other optical components, e.g., an optical filter or a pinhole, are placed underneath the light source in order to illuminate the cells with a coherent or quasi-coherent incident light. In this study, we demonstrate that contact imaging with an incident light of both limited temporal and spatial coherences can be achieved with sufficiently high quality for most applications in cell biology, including monitoring of cell sedimentation, rolling, adhesion, spreading, proliferation, motility, death and detachment. Patterns of cells were recorded at various distances between 0 and 1000 μm from the pixel array of the image sensors. Cells in suspension, just deposited or at mitosis focalise light into photonic nanojets which can be visualised by contact imaging. Light refraction by cells significantly varies during the adhesion process, the cell cycle and among the cell population in connection with every modification in the tridimensional morphology of a cell. PMID:26459014

  13. Time-lapse contact microscopy of cell cultures based on non-coherent illumination

    NASA Astrophysics Data System (ADS)

    Gabriel, Marion; Balle, Dorothée; Bigault, Stéphanie; Pornin, Cyrille; Gétin, Stéphane; Perraut, François; Block, Marc R.; Chatelain, François; Picollet-D'Hahan, Nathalie; Gidrol, Xavier; Haguet, Vincent

    2015-10-01

    Video microscopy offers outstanding capabilities to investigate the dynamics of biological and pathological mechanisms in optimal culture conditions. Contact imaging is one of the simplest imaging architectures to digitally record images of cells due to the absence of any objective between the sample and the image sensor. However, in the framework of in-line holography, other optical components, e.g., an optical filter or a pinhole, are placed underneath the light source in order to illuminate the cells with a coherent or quasi-coherent incident light. In this study, we demonstrate that contact imaging with an incident light of both limited temporal and spatial coherences can be achieved with sufficiently high quality for most applications in cell biology, including monitoring of cell sedimentation, rolling, adhesion, spreading, proliferation, motility, death and detachment. Patterns of cells were recorded at various distances between 0 and 1000 μm from the pixel array of the image sensors. Cells in suspension, just deposited or at mitosis focalise light into photonic nanojets which can be visualised by contact imaging. Light refraction by cells significantly varies during the adhesion process, the cell cycle and among the cell population in connection with every modification in the tridimensional morphology of a cell.

  14. 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

  15. Demand illumination control apparatus

    NASA Technical Reports Server (NTRS)

    Warren, Carl (Inventor); Arline, Jimmie (Inventor); LaPalme, Julius (Inventor)

    1981-01-01

    Solar illuminating compensating apparatus is disclosed whereby the interior of a building is illuminated to a substantially constant, predetermined level of light intensity by a combination of natural illumination from the sun and artificial illumination from electricity wherein the intensity of said artificial illumination is controlled by fully electronic means which increases the level of artificial illumination when the natural illumination is inadequate and vice versa.

  16. Full-hand 3D non-contact scanner using sub-window-based structured light-illumination technique

    NASA Astrophysics Data System (ADS)

    Yalla, Veeraganesh; Hassebrook, Laurence; Daley, Ray; Boles, Colby; Troy, Mike

    2012-06-01

    Fingerprint identification is a well-regarded and widely accepted modality in the field of biometrics for its high recognition rates. Legacy 2D contact based methods, though highly evolved in terms of technology suffer from certain drawbacks. Being contact based, there are many known issues which affect the recognition rates. Flashscan3D/University of Kentucky (UKY) developed state of the art 3D non-contact fingerprint scanners using different structured light illumination (SLI) techniques namely SLI single Point Of View (POV) and the SLI Subwindowing techniques. Capturing the fingerprints by non-contact means in 3D gives much higher quality fingerprint data which ultimately improves matching rates over a traditional 2D approach. In this paper, we present a full hand 3D non-contact scanner using the SLI Sub-windowing technique. Sample fingerprint data and experimental results for fingerprint matching based on a small sample 3D fingerprint test set are presented.

  17. Optical detectors based on thermoelastic effect in crystalline quartz

    NASA Astrophysics Data System (ADS)

    Chelibanov, V. P.; Ishanin, G. G.

    2015-06-01

    Optical detectors developed on base of thermo elastic effect In quartz crystalline (PTEK) attributed to the thermal detectors group. Such detectors occurred very effective for the registration of pulsed light energy or power of harmonically modulated laser radiation flux in a wide spectral (from UV to far IR) and dynamic ranges (from 10-6 to 300 W / cm2 with cooling) with a time constant up to10-6 seconds. When exposed to electromagnetic radiation occurs at the receiver thermal field which causes mechanical stress in the transient crystalline quartz, which in turn leads to a change in the polarization of crystalline quartz and, as a consequence, to an electric potential difference at the electrodes (the front surface with a conductive coating and damper). The capacitive characteristic of the detector, based on a thermo elastic effect in crystalline quartz, eliminates the possibility of working with constant flow of radiation, which also affects at the frequency response of the detector, since the potential difference appearance in the piezoelectric plate depends on the direction of the forces relative to the axes X, Y, Z of the crystal. Therefore, a certain choice of orientation of the receiving element is necessary in accordance with the physical properties of crystalline quartz. In this paper, a calculation of the sensitivity and frequency characteristics of optical detectors based on the thermo elastic effect in crystalline quartz at the harmonic effects of electromagnetic radiation flux are reported.

  18. The studies of Schottky-diode based co-plane detector for surface plasmon resonance sensing

    NASA Astrophysics Data System (ADS)

    Liu, Chien-Sheng; Wen, Tsun-Yu; Wang, Da-Shin; Lin, Chii-Wann

    2010-08-01

    The Surface Plasmon Resonance (SPR) is a label-free, highly sensitive and real time sensing technique and has been extensively applied to biosensing and assay for decades. In a conventional SPR biosensor, a prism is used to create the total reflection in which the evanescent wave can excite the surface plasmon mode at the metal-dielectric interface at certain angle, at which condition the reflectivity of incident TM-polarized vanished as measured by a far-field photodetector. This is the optical detection of surface plasmon resonance. In this research, zinc oxide (ZnO) was used as the dielectric thin-film material above the gold surface on the glass substrate to form a co-plane Schottky diode; this structure is designed to be an alternative way to detect SPR. The strength of plasmonic field is possible to be monitored by measuring the photocurrent under the reverse bias. According to our experimental results, the measured photocurrents with TM-polarized illumination (representing the SPR case), TE-polarized illumination (non-SPR case) and no illumination conditions under DC -1.5V bias are -76.158mA (2.5μA), -76.085mA (3.6μA) and -76.089mA (3.4μA), respectively. Based on the results, we have demonstrated this Schottky diode based co-plane device has the potential to be used as the SPR detector and provides a possible solution for the need of a low-cost, miniaturized, electronically integrated, and portable SPR biosensor in the near future.

  19. Alternative Packaging for Back-Illuminated Imagers

    NASA Technical Reports Server (NTRS)

    Pain, Bedabrata

    2009-01-01

    An alternative scheme has been conceived for packaging of silicon-based back-illuminated, back-side-thinned complementary metal oxide/semiconductor (CMOS) and charge-coupled-device image-detector integrated circuits, including an associated fabrication process. This scheme and process are complementary to those described in "Making a Back-Illuminated Imager With Back-Side Connections" (NPO-42839), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 38. To avoid misunderstanding, it should be noted that in the terminology of imaging integrated circuits, "front side" or "back side" does not necessarily refer to the side that, during operation, faces toward or away from a source of light or other object to be imaged. Instead, "front side" signifies that side of a semiconductor substrate upon which the pixel pattern and the associated semiconductor devices and metal conductor lines are initially formed during fabrication, and "back side" signifies the opposite side. If the imager is of the type called "back-illuminated," then the back side is the one that faces an object to be imaged. Initially, a back-illuminated, back-side-thinned image-detector is fabricated with its back side bonded to a silicon handle wafer. At a subsequent stage of fabrication, the front side is bonded to a glass wafer (for mechanical support) and the silicon handle wafer is etched away to expose the back side. The frontside integrated circuitry includes metal input/output contact pads, which are rendered inaccessible by the bonding of the front side to the glass wafer. Hence, one of the main problems is to make the input/output contact pads accessible from the back side, which is ultimately to be the side accessible to the external world. The present combination of an alternative packaging scheme and associated fabrication process constitute a solution of the problem.

  20. Particle detectors based on semiconducting InP epitaxial layers

    NASA Astrophysics Data System (ADS)

    Yatskiv, R.; Grym, J.; Zdansky, K.

    2011-01-01

    A study of electrical properties and detection performance of two types of Indium Phosphide detector structures was performed: (i) with p-n-junction and (ii) with Schottky contact prepared on high purity p-type InP. The p-n junction detectors were based on a high purity InP:Pr layers of both n- and p- type conductivity with carrier concentration on the order of 1014 cm-3 grown on Sn doped n-type substrate. Schottky barrier detectors were prepared by vacuum evaporation of Pd on high purity p-type epitaxial layer grown on Mn doped p-type substrate. The detection performance of particle detectors was measured by pulse-height spectra with alpha particles emitted from 241Am source at room temperature.

  1. Asymmetric masks for laboratory-based X-ray phase-contrast imaging with edge illumination

    NASA Astrophysics Data System (ADS)

    Endrizzi, Marco; Astolfo, Alberto; Vittoria, Fabio A.; Millard, Thomas P.; Olivo, Alessandro

    2016-05-01

    We report on an asymmetric mask concept that enables X-ray phase-contrast imaging without requiring any movement in the system during data acquisition. The method is compatible with laboratory equipment, namely a commercial detector and a rotating anode tube. The only motion required is that of the object under investigation which is scanned through the imaging system. Two proof-of-principle optical elements were designed, fabricated and experimentally tested. Quantitative measurements on samples of known shape and composition were compared to theory with good agreement. The method is capable of measuring the attenuation, refraction and (ultra-small-angle) X-ray scattering, does not have coherence requirements and naturally adapts to all those situations in which the X-ray image is obtained by scanning a sample through the imaging system.

  2. Asymmetric masks for laboratory-based X-ray phase-contrast imaging with edge illumination

    PubMed Central

    Endrizzi, Marco; Astolfo, Alberto; Vittoria, Fabio A.; Millard, Thomas P.; Olivo, Alessandro

    2016-01-01

    We report on an asymmetric mask concept that enables X-ray phase-contrast imaging without requiring any movement in the system during data acquisition. The method is compatible with laboratory equipment, namely a commercial detector and a rotating anode tube. The only motion required is that of the object under investigation which is scanned through the imaging system. Two proof-of-principle optical elements were designed, fabricated and experimentally tested. Quantitative measurements on samples of known shape and composition were compared to theory with good agreement. The method is capable of measuring the attenuation, refraction and (ultra-small-angle) X-ray scattering, does not have coherence requirements and naturally adapts to all those situations in which the X-ray image is obtained by scanning a sample through the imaging system. PMID:27145924

  3. Asymmetric masks for laboratory-based X-ray phase-contrast imaging with edge illumination.

    PubMed

    Endrizzi, Marco; Astolfo, Alberto; Vittoria, Fabio A; Millard, Thomas P; Olivo, Alessandro

    2016-01-01

    We report on an asymmetric mask concept that enables X-ray phase-contrast imaging without requiring any movement in the system during data acquisition. The method is compatible with laboratory equipment, namely a commercial detector and a rotating anode tube. The only motion required is that of the object under investigation which is scanned through the imaging system. Two proof-of-principle optical elements were designed, fabricated and experimentally tested. Quantitative measurements on samples of known shape and composition were compared to theory with good agreement. The method is capable of measuring the attenuation, refraction and (ultra-small-angle) X-ray scattering, does not have coherence requirements and naturally adapts to all those situations in which the X-ray image is obtained by scanning a sample through the imaging system. PMID:27145924

  4. Avalanche photodiode based detector for beam emission spectroscopy

    SciTech Connect

    Dunai, D.; Zoletnik, S.; Sarkoezi, J.; Field, A. R.

    2010-10-15

    An avalanche photodiode based (APD) detector for the visible wavelength range was developed for low light level, high frequency beam emission spectroscopy (BES) experiments in fusion plasmas. This solid state detector has higher quantum efficiency than photomultiplier tubes, and unlike normal photodiodes, it has internal gain. This paper describes the developed detector as well as the noise model of the electronic circuit. By understanding the noise sources and the amplification process, the optimal amplifier and APD reverse voltage setting can be determined, where the signal-to-noise ratio is the highest for a given photon flux. The calculations are compared to the absolute calibration results of the implemented circuit. It was found that for a certain photon flux range, relevant for BES measurements ({approx_equal}10{sup 8}-10{sup 10} photons/s), the new detector is superior to both photomultipliers and photodiodes, although it does not require cryogenic cooling of any component. The position of this photon flux window sensitively depends on the parameters of the actual experimental implementation (desired bandwidth, detector size, etc.) Several detector units based on these developments have been built and installed in various tokamaks. Some illustrative results are presented from the 8-channel trial BES system installed at Mega-Ampere Spherical Tokamak (MAST) and the 16-channel BES system installed at the Torus Experiment for Technology Oriented Research (TEXTOR).

  5. Integrated atom detector based on field ionization near carbon nanotubes

    SciTech Connect

    Gruener, B.; Jag, M.; Stibor, A.; Visanescu, G.; Haeffner, M.; Kern, D.; Guenther, A.; Fortagh, J.

    2009-12-15

    We demonstrate an atom detector based on field ionization and subsequent ion counting. We make use of field enhancement near tips of carbon nanotubes to reach extreme electrostatic field values of up to 9x10{sup 9} V/m, which ionize ground-state rubidium atoms. The detector is based on a carpet of multiwall carbon nanotubes grown on a substrate and used for field ionization, and a channel electron multiplier used for ion counting. We measure the field enhancement at the tips of carbon nanotubes by field emission of electrons. We demonstrate the operation of the field ionization detector by counting atoms from a thermal beam of a rubidium dispenser source. By measuring the ionization rate of rubidium as a function of the applied detector voltage we identify the field ionization distance, which is below a few tens of nanometers in front of nanotube tips. We deduce from the experimental data that field ionization of rubidium near nanotube tips takes place on a time scale faster than 10{sup -10} s. This property is particularly interesting for the development of fast atom detectors suitable for measuring correlations in ultracold quantum gases. We also describe an application of the detector as partial pressure gauge.

  6. High-nitrogen-based pyrotechnics: development of perchlorate-free green-light illuminants for military and civilian applications.

    PubMed

    Sabatini, Jesse J; Raab, James M; Hann, Ronald K; Damavarapu, Reddy; Klapötke, Thomas M

    2012-06-01

    The development of perchlorate-free hand-held signal illuminants for the US Army's M195 green star parachute is described. Compared with the perchlorate-containing control, the optimized perchlorate-free illuminants were less sensitive toward various ignition stimuli while offering comparable burn times and visible-light outputs. The results were also important from the perspective of civilian fireworks because the development of perchlorate-free illuminants remains an important objective of the commercial fireworks industry. PMID:22488721

  7. Instrumentation for Kinetic-Inductance-Detector-Based Submillimeter Radio Astronomy

    NASA Astrophysics Data System (ADS)

    Duan, Ran

    A substantial amount of important scientific information is contained within astronomical data at the submillimeter and far-infrared (FIR) wavelengths, including information regarding dusty galaxies, galaxy clusters, and star-forming regions; however, these wavelengths are among the least-explored fields in astronomy because of the technological difficulties involved in such research. Over the past 20 years, considerable efforts have been devoted to developing submillimeter- and millimeter-wavelength astronomical instruments and telescopes. The number of detectors is an important property of such instruments and is the subject of the current study. Future telescopes will require as many as hundreds of thousands of detectors to meet the necessary requirements in terms of the field of view, scan speed, and resolution. A large pixel count is one benefit of the development of multiplexable detectors that use kinetic inductance detector (KID) technology. This dissertation presents the development of a KID-based instrument including a portion of the millimeter-wave bandpass filters and all aspects of the readout electronics, which together enabled one of the largest detector counts achieved to date in submillimeter-/millimeter-wavelength imaging arrays: a total of 2304 detectors. The work presented in this dissertation has been implemented in the MUltiwavelength Submillimeter Inductance Camera (MUSIC), a new instrument for the Caltech Submillimeter Observatory (CSO).

  8. Hotsphere illumination

    NASA Astrophysics Data System (ADS)

    Razavi, Bahar S.; Kuzyakov, Yakov

    2016-04-01

    Soils are the most heterogeneous parts of the biosphere, with an extremely high differentiation of properties and processes at all spatial and temporal scales. Importance of the hotspheres such as rhizosphere, detritusphere, porosphere (including drilosphere and biopores), hyphasphere and spermosphere, calls for spatially explicit methods to illuminate distribution of microbial activities in these hotspheres (Kuzyakov and Blagodatskaya, 2015). Zymography technique has previously been adapted to visualize the spatial dynamics of enzyme activities in rhizosphere (Spohn and Kuzyakov, 2014). Here, we further developed soil zymography to obtain a higher resolution of enzyme activities by enabling direct contact of substrate-saturated membranes with soil. For the first time, we aimed at quantitative imaging of enzyme activities in various hotspheres. We calculated and compared percentage of enzymatic hotspots of five hotspheres: spermosphere, rhizosphere, detritusphere, drilosphere and biopores. Spatial distribution of activities of two enzymes: β-glucosidase and leucine amino peptidase were analyzed in the spermosphere, rhizosphere and detritusphere of maize and lentil. Zymography has been done 3 days (spermosphere), 14 days (rhizosphere) after sowing and 21 days after cutting plant (detritusphere). Spatial resolution of fluorescent images was improved by direct application fluorogenically labelled substrates on the soil surface. Such improvement enabled to visualize enzyme distribution of mycorrhiza hypha on the rhizobox surface. Further, to visualize the 2D distribution of the enzyme activities in porosphere, we placed earthworms (Lumbricus terrestris), (drilosphere) and ground beetle species Platynus dorsalis Pont. (Coleoptera; Carabidae), (biopore), in transparent boxes for 2weeks. The developed in situ zymography visualized the heterogeneity of enzyme activities along and across the roots. Spatial patterns of enzyme activities as a function of distance along the

  9. High Throughput, High Yield Fabrication of High Quantum Efficiency Back-Illuminated Photon Counting, Far UV, UV, and Visible Detector Arrays

    NASA Technical Reports Server (NTRS)

    Nikzad, Shouleh; Hoenk, M. E.; Carver, A. G.; Jones, T. J.; Greer, F.; Hamden, E.; Goodsall, T.

    2013-01-01

    In this paper we discuss the high throughput end-to-end post fabrication processing of high performance delta-doped and superlattice-doped silicon imagers for UV, visible, and NIR applications. As an example, we present our results on far ultraviolet and ultraviolet quantum efficiency (QE) in a photon counting, detector array. We have improved the QE by nearly an order of magnitude over microchannel plates (MCPs) that are the state-of-the-art UV detectors for many NASA space missions as well as defense applications. These achievements are made possible by precision interface band engineering of Molecular Beam Epitaxy (MBE) and Atomic Layer Deposition (ALD).

  10. Fast volumetric imaging with patterned illumination via digital micro-mirror device-based temporal focusing multiphoton microscopy

    PubMed Central

    Chang, Chia-Yuan; Hu, Yvonne Yuling; Lin, Chun-Yu; Lin, Cheng-Han; Chang, Hsin-Yu; Tsai, Sheng-Feng; Lin, Tzu-Wei; Chen, Shean-Jen

    2016-01-01

    Temporal focusing multiphoton microscopy (TFMPM) has the advantage of area excitation in an axial confinement of only a few microns; hence, it can offer fast three-dimensional (3D) multiphoton imaging. Herein, fast volumetric imaging via a developed digital micromirror device (DMD)-based TFMPM has been realized through the synchronization of an electron multiplying charge-coupled device (EMCCD) with a dynamic piezoelectric stage for axial scanning. The volumetric imaging rate can achieve 30 volumes per second according to the EMCCD frame rate of more than 400 frames per second, which allows for the 3D Brownian motion of one-micron fluorescent beads to be spatially observed. Furthermore, it is demonstrated that the dynamic HiLo structural multiphoton microscope can reject background noise by way of the fast volumetric imaging with high-speed DMD patterned illumination. PMID:27231617

  11. Fast volumetric imaging with patterned illumination via digital micro-mirror device-based temporal focusing multiphoton microscopy.

    PubMed

    Chang, Chia-Yuan; Hu, Yvonne Yuling; Lin, Chun-Yu; Lin, Cheng-Han; Chang, Hsin-Yu; Tsai, Sheng-Feng; Lin, Tzu-Wei; Chen, Shean-Jen

    2016-05-01

    Temporal focusing multiphoton microscopy (TFMPM) has the advantage of area excitation in an axial confinement of only a few microns; hence, it can offer fast three-dimensional (3D) multiphoton imaging. Herein, fast volumetric imaging via a developed digital micromirror device (DMD)-based TFMPM has been realized through the synchronization of an electron multiplying charge-coupled device (EMCCD) with a dynamic piezoelectric stage for axial scanning. The volumetric imaging rate can achieve 30 volumes per second according to the EMCCD frame rate of more than 400 frames per second, which allows for the 3D Brownian motion of one-micron fluorescent beads to be spatially observed. Furthermore, it is demonstrated that the dynamic HiLo structural multiphoton microscope can reject background noise by way of the fast volumetric imaging with high-speed DMD patterned illumination. PMID:27231617

  12. A mass spectrometer based explosives trace detector

    NASA Astrophysics Data System (ADS)

    Vilkov, Andrey; Jorabchi, Kaveh; Hanold, Karl; Syage, Jack A.

    2011-05-01

    In this paper we describe the application of mass spectrometry (MS) to the detection of trace explosives. We begin by reviewing the issue of explosives trace detection (ETD) and describe the method of mass spectrometry (MS) as an alternative to existing technologies. Effective security screening devices must be accurate (high detection and low false positive rate), fast and cost effective (upfront and operating costs). Ion mobility spectrometry (IMS) is the most commonly deployed method for ETD devices. Its advantages are compact size and relatively low price. For applications requiring a handheld detector, IMS is an excellent choice. For applications that are more stationary (e.g., checkpoint and alternatives to IMS are available. MS is recognized for its superior performance with regard to sensitivity and specificity, which translate to lower false negative and false positive rates. In almost all applications outside of security where accurate chemical analysis is needed, MS is usually the method of choice and is often referred to as the gold standard for chemical analysis. There are many review articles and proceedings that describe detection technologies for explosives. 1,2,3,4 Here we compare MS and IMS and identify the strengths and weaknesses of each method. - Mass spectrometry (MS): MS offers high levels of sensitivity and specificity compared to other technologies for chemical detection. Its traditional disadvantages have been high cost and complexity. Over the last few years, however, the economics have greatly improved and MS is now capable of routine and automated operation. Here we compare MS and IMS and identify the strengths and weaknesses of each method. - Ion mobility spectrometry (IMS): 5 MS-ETD Screening System IMS is similar in concept to MS except that the ions are dispersed by gas-phase viscosity and not by molecular weight. The main advantage of IMS is that it does not use a vacuum system, which greatly reduces the size, cost, and complexity

  13. Development of a NDVI detector based on optics and spectroscopy

    NASA Astrophysics Data System (ADS)

    Yang, Wei; Li, Minzan; Sun, Hong; Zhao, Ruijiao

    2012-01-01

    A NDVI detector is developed based on ground-based remote sensing, which uses proper wavebands and embeds a new optimization algorithm of nitrogen fertilization. The detector has two main units, optical unit and electronic unit. In optical unit there are four special different photoelectrical sensors used for detecting sunlight incidence and reflect light of plant canopy in red and NIR wavebands, respectively. Analog signals measured by sensors are amplified and then converted to digital in electronic unit. After processing the digital signal, NDVI of the plant can be calculated. Performance and stability experiments are conducted to cucumber plants in greenhouse. The results show that the detector has a good stability. In order to eliminate the error from sunlight a new artificial light source is suggested.

  14. GEM-based detectors for thermal and fast neutrons

    NASA Astrophysics Data System (ADS)

    Croci, G.; Claps, G.; Cazzaniga, C.; Foggetta, L.; Muraro, A.; Valente, P.

    2015-06-01

    Lately the problem of 3He replacement for neutron detection stimulated an intense activity research on alternative technologies based on alternative neutron converters. This paper presents briefly the results obtained with new GEM detectors optimized for fast and thermal neutrons. For thermal neutrons, we realized a side-on GEM detector based on a series of boron-coated alumina sheets placed perpendicularly to the incident neutron beam direction. This prototype has been tested at n@BTF photo-production neutron facilty in order to test its effectiveness under a very high flux gamma background. For fast neutrons, we developed new GEM detectors (called nGEM) for the CNESM diagnostic system of the SPIDER NBI prototype for ITER (RFX-Consortium, Italy) and as beam monitor for fast neutrons lines at spallation sources. The nGEM is a Triple GEM gaseous detector equipped with a polyethylene layer used to convert fast neutrons into recoil protons through the elastic scattering process. This paper describes the results obtained by testing a medium size (30 × 25 cm2 active area) nGEM detector at the ISIS spallation source on the VESUVIO beam line.

  15. Extracting roads based on Retinex and improved Canny operator with shape criteria in vague and unevenly illuminated aerial images

    NASA Astrophysics Data System (ADS)

    Ronggui, Ma; Weixing, Wang; Sheng, Liu

    2012-01-01

    An automatic road extraction method for vague aerial images is proposed in this paper. First, a high-resolution but low-contrast image is enhanced by using a Retinex-based algorithm. Then, the enhanced image is segmented with an improved Canny edge detection operator that can automatically threshold the image into a binary edge image. Subsequently, the linear and curved road segments are regulated by the Hough line transform and extracted based on several thresholds of road size and shapes, in which a number of morphological operators are used such as thinning (skeleton), junction detection, and endpoint detection. In experiments, a number of vague aerial images with bad uniformity are selected for testing. Similarity and discontinuation-based algorithms, such as Otsu thresholding, merge and split, edge detection-based algorithms, and the graph-based algorithm are compared with the new method. The experiment and comparison results show that the studied method can enhance vague, low-contrast, and unevenly illuminated color aerial road images; it can detect most road edges with fewer disturb elements and trace roads with good quality. The method in this study is promising.

  16. Hydrazine Detectors Based On Raman Scattering

    NASA Technical Reports Server (NTRS)

    Rupich, Martin W.; Carrabba, Michael M.

    1992-01-01

    Goal of sensor-development program to measure concentrations as low as few parts per billion in continuous monitoring as well as peak concentrations up to hundreds of parts per million, such as encountered near leaks. Sensors based on Raman scattering from hydrazine or monomethyl hydrazine adsorbed on roughened metal or metal oxide substrates. Similar systems developed to detect nitrogen oxides and other gases.

  17. Investigation of the spectral properties of LED-based MR16s for general illumination

    NASA Astrophysics Data System (ADS)

    Brown, David F.; Nicol, David B.; Payne, Adam; Ferguson, Ian T.

    2004-10-01

    The spectral properties of commercially available LED-based and halogen MR16s were investigated. The measurements taken include TLF (Total Luminous Flux), CCT (Correlated Color Temperature), CRI (Color Rendering Index), angular variation of CCT, and luminous efficacy. The halogen MR16s were used as a baseline for comparison with LED-based MR16s. It is shown at this time that LED-based MR16s are not suitable as a direct replacement for existing alternatives due to high initial cost, low power efficiency, poor CRIs, and undesirable CCTs.

  18. Zinc Oxide Nanorod Based Ultraviolet Detectors with Wheatstone Bridge Design

    NASA Astrophysics Data System (ADS)

    Vasudevan, Arun

    This research work, for the first time, investigated metal semiconductor-metal (MSM) zine oxide (ZnO) nanorod based ultra-violet (UV) detectors having a Wheatstone bridge design with a high responsivity at room temperature and above, as well as a responsivity that was largely independent of the change in ambient conditions. The ZnO nanorods which acted as the sensing element of the detector were grown by a chemical growth technique. Studies were conducted to determine the effects on ZnO nanorod properties by varying the concentration of the chemicals used for the rod growth. These studies showed how the rod diameter and the deposition of ZnO nanorods from the solution was controlled by varying the concentration of the chemicals used for the rod growth. Conventional MSM UV detectors were fabricated with ZnO nanorods grown under optimized conditions to determine the dependence of UV response on electrode dimension and rod dimension. These studies gave insights into the dependence of UV response on the width of the electrode, spacing between the electrodes, density of the rod growth, and length and diameter of the rods. The UV responsivity was affected by varying the number of times the seed layer was spin coated, by varying the spin speed of seed layer coating and by varying the annealing temperature of the seed and rod. Based on these studies, optimum conditions for the fabrication of Wheatstone bridge UV ZnO nanorod detectors were determined. The Wheatstone bridge ZnO nanorod UV detectors were fabricated in three different configurations, namely, symmetric, asymmetric, and quasi-symmetric. The transient responses of the symmetric, asymmetric and quasi-symmetric configurations at room temperature and above showed how the response stability differed. At high temperature the responsivity of quasi-symmetric Wheatstone bridge detector configuration did not drop after saturation and the responsivity drifted by 17% to 25% from the room temperature response

  19. Investigation of the spectral properties of LED-based MR16 bulbs for general illumination

    NASA Astrophysics Data System (ADS)

    Brown, David F.; Nicol, David B.; Ferguson, Ian T.

    2005-11-01

    The spectral properties of commercially available halogen and LED-based MR16s were investigated. The metrics used to characterize the MR16s include the total luminous flux (TLF), correlated color temperature (CCT), color-rendering index (CRI), angular variation of CCT, and luminous efficacy. The halogen MR16s were included as a baseline for comparison with LED-based MR16s. Seven LED-based MR16s were investigated, including three constructed from 5-mm LEDs, and four constructed from high-power devices based on a larger die. It is shown that MR16s constructed from white LEDs are not suitable as a direct replacement for existing alternatives at this time, due to their low power efficiency and poor TLF. MR16s constructed with a single phosphor also have poor CRIs and undesirable CCTs. An MR16 with an extra phosphor in the red region of the spectrum shows improvement in CRI and a lower CCT than the other LED-based MR16s. All of the LED-based MR16s had a variation of CCT that was larger than those of the halogen devices.

  20. Polycrystalline diamond based detector for Z-pinch plasma diagnosis

    SciTech Connect

    Liu Linyue; Zhao Jizhen; Chen Liang; Ouyang Xiaoping; Wang Lan

    2010-08-15

    A detector setup based on polycrystalline chemical-vapor-deposition diamond film is developed with great characteristics: low dark current (lower than 60 pA within 3 V/{mu}m), fast pulsed response time (rise time: 2-3 ns), flat spectral response (3-5 keV), easy acquisition, low cost, and relative large sensitive area. The characterizing data on Qiangguang-I accelerator show that this detector can satisfy the practical requirements in Z-pinch plasma diagnosis very well, which offers a promising prototype for the x-ray detection in Z-pinch diagnosis.

  1. A Weak Value Based QKD Protocol Robust Against Detector Attacks

    NASA Astrophysics Data System (ADS)

    Troupe, James

    2015-03-01

    We propose a variation of the BB84 quantum key distribution protocol that utilizes the properties of weak values to insure the validity of the quantum bit error rate estimates used to detect an eavesdropper. The protocol is shown theoretically to be secure against recently demonstrated attacks utilizing detector blinding and control and should also be robust against all detector based hacking. Importantly, the new protocol promises to achieve this additional security without negatively impacting the secure key generation rate as compared to that originally promised by the standard BB84 scheme. Implementation of the weak measurements needed by the protocol should be very feasible using standard quantum optical techniques.

  2. Universal ultrafast detector for short optical pulses based on graphene.

    PubMed

    Mittendorff, Martin; Kamann, Josef; Eroms, Jonathan; Weiss, Dieter; Drexler, Christoph; Ganichev, Sergey D; Kerbusch, Jochen; Erbe, Artur; Suess, Ryan J; Murphy, Thomas E; Chatterjee, Sangam; Kolata, Kolja; Ohser, Joachim; König-Otto, Jacob C; Schneider, Harald; Helm, Manfred; Winnerl, Stephan

    2015-11-01

    Graphene has unique optical and electronic properties that make it attractive as an active material for broadband ultrafast detection. We present here a graphene-based detector that shows 40-picosecond electrical rise time over a spectral range that spans nearly three orders of magnitude, from the visible to the far-infrared. The detector employs a large area graphene active region with interdigitated electrodes that are connected to a log-periodic antenna to improve the long-wavelength collection efficiency, and a silicon carbide substrate that is transparent throughout the visible regime. The detector exhibits a noise-equivalent power of approximately 100 µW·Hz(-½) and is characterized at wavelengths from 780 nm to 500 µm. PMID:26561141

  3. Experimental characterization of semiconductor-based thermal neutron detectors

    NASA Astrophysics Data System (ADS)

    Bedogni, R.; Bortot, D.; Pola, A.; Introini, M. V.; Lorenzoli, M.; Gómez-Ros, J. M.; Sacco, D.; Esposito, A.; Gentile, A.; Buonomo, B.; Palomba, M.; Grossi, A.

    2015-04-01

    In the framework of NESCOFI@BTF and NEURAPID projects, active thermal neutron detectors were manufactured by depositing appropriate thickness of 6LiF on commercially available windowless p-i-n diodes. Detectors with different radiator thickness, ranging from 5 to 62 μm, were manufactured by evaporation-based deposition technique and exposed to known values of thermal neutron fluence in two thermal neutron facilities exhibiting different irradiation geometries. The following properties of the detector response were investigated and presented in this work: thickness dependence, impact of parasitic effects (photons and epithermal neutrons), linearity, isotropy, and radiation damage following exposure to large fluence (in the order of 1012 cm-2).

  4. X-ray detectors based on GaN

    NASA Astrophysics Data System (ADS)

    Duboz, J. Y.; Frayssinet, E.; Chenot, Sebastien; Reverchon, J. L.; Idir, M.

    2013-03-01

    The potential of GaN for X-ray detection in the range from 5 to 40 keV has been assessed. The absorption coefficient has been measured as a fonction of photon energy. Various detectors have been fabricated including MSM and Schottky diodes. They were tested under polychromatic X-ray illumination and under monochromatic irradiation from 6 to 22 keV in the Soleil synchrotron facility. The vertical Schottky diodes perform better as their geometry is better suited to the thick layers required by the low absorption coefficient. The operation mode is discussed in terms of photoconductive and photovoltaic behaviors. Some parasitic effects related to the electrical activation of defects by high energy photons and to the tunnel effect in lightly doped Schottky diodes have been evidenced. These effects disappear in diodes where the doping profile has been optimized. The spectral response is found to be very consistent with the spectral absorption coefficient. The sensitivity of GaN Schottky diodes is evaluated and found to be on the order of 40 photons per second. The response is fast nd linear.

  5. Passive polarimetric imagery-based material classification robust to illumination source position and viewpoint.

    PubMed

    Thilak Krishna, Thilakam Vimal; Creusere, Charles D; Voelz, David G

    2011-01-01

    Polarization, a property of light that conveys information about the transverse electric field orientation, complements other attributes of electromagnetic radiation such as intensity and frequency. Using multiple passive polarimetric images, we develop an iterative, model-based approach to estimate the complex index of refraction and apply it to target classification. PMID:20542767

  6. Illuminating Spatial and Temporal Organization of Protein Interaction Networks by Mass Spectrometry-Based Proteomics

    PubMed Central

    Yang, Jiwen; Wagner, Sebastian A.; Beli, Petra

    2015-01-01

    Protein–protein interactions are at the core of all cellular functions and dynamic alterations in protein interactions regulate cellular signaling. In the last decade, mass spectrometry (MS)-based proteomics has delivered unprecedented insights into human protein interaction networks. Affinity purification-MS (AP-MS) has been extensively employed for focused and high-throughput studies of steady state protein–protein interactions. Future challenges remain in mapping transient protein interactions after cellular perturbations as well as in resolving the spatial organization of protein interaction networks. AP-MS can be combined with quantitative proteomics approaches to determine the relative abundance of purified proteins in different conditions, thereby enabling the identification of transient protein interactions. In addition to affinity purification, methods based on protein co-fractionation have been combined with quantitative MS to map transient protein interactions during cellular signaling. More recently, approaches based on proximity tagging that preserve the spatial dimension of protein interaction networks have been introduced. Here, we provide an overview of MS-based methods for analyzing protein–protein interactions with a focus on approaches that aim to dissect the temporal and spatial aspects of protein interaction networks. PMID:26648978

  7. Transnasal illumination to guide the craniofacial resection of anterior skull base neoplasms.

    PubMed

    Cohen, A R; Tartell, P B

    1993-11-01

    The authors describe use of a flexible fiberoptic light source to guide the craniofacial resection of anterior skull base neoplasms. The light is introduced transnasally and serves to outline the perimeter of the tumor, helping to direct the safe placement of intracranial osteotomies and en bloc tumor removal. PMID:8211661

  8. Beta ray spectroscopy based on a plastic scintillation detector/silicon surface barrier detector coincidence telescope

    NASA Astrophysics Data System (ADS)

    Horowitz, Y. S.; Hirning, C. R.; Yuen, P.; Aikens, M.

    1994-01-01

    Beta radiation is now recognized as a significant radiation safety problem and several international conferences have recently been devoted to the problems of mixed field beta/photon dosimetry. Conventional dosimetry applies algorithms to thermoluminescence dosimetry (TLD) multi-element badges which attempt to extract dose information based on the comparison of TL signals from ``thick/thin'' and/or ``bare/filtered'' elements. These may be grossly innacurate due to inadequate or non-existant knowledge of the energy spectrum of both the beta radiation and the accompanying photon field, as well as other factors. In this paper, we discuss the operation of a beta-ray energy spectrometer based on a two element, E × dE detector telescope intended to support dose algorithms with beta spectral information. Beta energies are measured via a 5 cm diameter × 2 cm thick BC-404 plastic scintillator preceded by a single, 100 μm thick, totally depleted, silicon dE detector. Photon events in the E detector are rejected by requiring a coincidence between the E and dE detectors. Photon rejection ratios vary from 225:1 at 1.25 MeV (60Co) to 360:1 at 0.36 MeV (133Ba). The spectrometer is capable of measuring electron energies from a lower energy coincidence threshold of approximately 125 keV to an upper limit of 3.5 MeV. This energy range spans the great majority of beta-emitting radionuclides in nuclear facilities.

  9. Skyrmion based microwave detectors and harvesting

    SciTech Connect

    Finocchio, G.; Giordano, A.; Ricci, M.; Burrascano, P.; Tomasello, R.; Lanuzza, M.; Puliafito, V.; Azzerboni, B.; Carpentieri, M.

    2015-12-28

    Magnetic skyrmions are topologically protected states that are very promising for the design of the next generation of ultra-low-power electronic devices. In this letter, we propose a magnetic tunnel junction based spin-transfer torque diode with a magnetic skyrmion as ground state and a perpendicular polarizer patterned as nano-contact for a local injection of the current. The key result is the possibility to achieve sensitivities (i.e., detection voltage over input microwave power) larger than 2000 V/W for optimized contact diameters. We also pointed out that large enough voltage controlled magnetocrystalline anisotropy could significantly improve the sensitivity. Our results can be very useful for the identification of a class of spin-torque diodes with a non-uniform ground state and to understand the fundamental physics of the skyrmion dynamical properties.

  10. New oscillation detector system based on the moiré technique

    NASA Astrophysics Data System (ADS)

    Esmaeili, Shamseddin; Ansari, Anooshiravan; Hamzehloo, Hosseain

    2015-10-01

    We have described a method to detect characteristics of an oscillation system based on the moiré technique. We can determine amplitude, resonance frequency, and damping coefficient of an oscillating system both in vertical and horizontal directions. For this approach, the displacement of the oscillatory mass must be accurately determined. The displacement is recorded by the moiré detecting procedure. A spring-suspended mass, whose position is monitored by moiré technique, is used to test this idea. Our detecting system consists of a pair of similar gratings which are installed near each other without physical contact. The planes of the gratings are parallel and the lines of gratings have a small angle with respect to each other. Also, a laser diode, a silicon photo-diode, and a narrow slit have been used and fixed to the frame to illuminate fringes' displacement due to the suspended mass movement. The displacement of the mass relative to the fixed grating changes the light intensity on the detector. The intensity of the light is recorded as voltage by the light detector. The output voltage can be used to measure the oscillator movement. This method can detect displacements of the order of microns. Also, the experimental result and theoretical simulation are compared.

  11. Active illumination based 3D surface reconstruction and registration for image guided medialization laryngoplasty

    NASA Astrophysics Data System (ADS)

    Jin, Ge; Lee, Sang-Joon; Hahn, James K.; Bielamowicz, Steven; Mittal, Rajat; Walsh, Raymond

    2007-03-01

    The medialization laryngoplasty is a surgical procedure to improve the voice function of the patient with vocal fold paresis and paralysis. An image guided system for the medialization laryngoplasty will help the surgeons to accurately place the implant and thus reduce the failure rates of the surgery. One of the fundamental challenges in image guided system is to accurately register the preoperative radiological data to the intraoperative anatomical structure of the patient. In this paper, we present a combined surface and fiducial based registration method to register the preoperative 3D CT data to the intraoperative surface of larynx. To accurately model the exposed surface area, a structured light based stereo vision technique is used for the surface reconstruction. We combined the gray code pattern and multi-line shifting to generate the intraoperative surface of the larynx. To register the point clouds from the intraoperative stage to the preoperative 3D CT data, a shape priori based ICP method is proposed to quickly register the two surfaces. The proposed approach is capable of tracking the fiducial markers and reconstructing the surface of larynx with no damage to the anatomical structure. We used off-the-shelf digital cameras, LCD projector and rapid 3D prototyper to develop our experimental system. The final RMS error in the registration is less than 1mm.

  12. Interferometer-based structured-illumination microscopy utilizing complementary phase relationship through constructive and destructive image detection by two cameras.

    PubMed

    Shao, L; Winoto, L; Agard, D A; Gustafsson, M G L; Sedat, J W

    2012-06-01

    In an interferometer-based fluorescence microscope, a beam splitter is often used to combine two emission wavefronts interferometrically. There are two perpendicular paths along which the interference fringes can propagate and normally only one is used for imaging. However, the other path also contains useful information. Here we introduced a second camera to our interferometer-based three-dimensional structured-illumination microscope (I(5)S) to capture the fringes along the normally unused path, which are out of phase by π relative to the fringes along the other path. Based on this complementary phase relationship and the well-defined phase interrelationships among the I(5)S data components, we can deduce and then computationally eliminate the path length errors within the interferometer loop using the simultaneously recorded fringes along the two imaging paths. This self-correction capability can greatly relax the requirement for eliminating the path length differences before and maintaining that status during each imaging session, which are practically challenging tasks. Experimental data is shown to support the theory. PMID:22472010

  13. Predicting Ground Illuminance

    NASA Astrophysics Data System (ADS)

    Lesniak, Michael V.

    2014-01-01

    Our Sun outputs 3.85 × 1026 W of radiation, of which ≈37% is in the visible band. It is directly responsible for nearly all natural illuminance experienced on Earth's surface, either in the form of direct/refracted sunlight or in reflected light bouncing off the surfaces and/or atmospheres of our Moon and the visible planets. Ground illuminance, defined as the amount of visible light intercepting a unit area of surface (from all incident angles), varies over 7 orders of magnitude from day to night. It is highly dependent on well-modeled factors such as the relative positions of the Sun, Earth, and Moon. It is also dependent on less predictable factors such as local atmospheric conditions and weather. Several models have been proposed to predict ground illuminance, including Brown (1952) and Shapiro (1982, 1987). The Brown model is a set of empirical data collected from observation points around the world that has been reduced to a smooth fit of illuminance against a single variable, solar altitude. It provides limited applicability to the Moon and for cloudy conditions via multiplicative reduction factors. The Shapiro model is a theoretical model that treats the atmosphere as a three layer system of light reflectance and transmittance. It has different sets of reflectance and transmittance coefficients for various cloud types. Ground illuminance data from an observing run at the White Sands missile range were obtained from the United Kingdom Meteorology Office. Based on available weather reports, five days of clear sky observations were selected. These data are compared to the predictions of the two models. We find that neither of the models provide an accurate treatment during twilight conditions when the Sun is at or a few degrees below the horizon. When the Sun is above the horizon, the Shapiro model straddles the observed data, ranging between 90% and 120% of the recorded illuminance. During the same times, the Brown model is between 70% and 90% of the

  14. Photoacoustic-based detector for infrared laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Scholz, L.; Palzer, S.

    2016-07-01

    In this contribution, we present an alternative detector technology for use in direct absorption spectroscopy setups. Instead of a semiconductor based detector, we use the photoacoustic effect to gauge the light intensity. To this end, the target gas species is hermetically sealed under excess pressure inside a miniature cell along with a MEMS microphone. Optical access to the cell is provided by a quartz window. The approach is particularly suitable for tunable diode laser spectroscopy in the mid-infrared range, where numerous molecules exhibit large absorption cross sections. Moreover, a frequency standard is integrated into the method since the number density and pressure inside the cell are constant. We demonstrate that the information extracted by our method is at least equivalent to that achieved using a semiconductor-based photon detector. As exemplary and highly relevant target gas, we have performed direct spectroscopy of methane at the R3-line of the 2v3 band at 6046.95 cm-1 using both detector technologies in parallel. The results may be transferred to other infrared-active transitions without loss of generality.

  15. Characterization of a GEM-based fast neutron detector

    NASA Astrophysics Data System (ADS)

    Esposito, B.; Marocco, D.; Villari, R.; Murtas, F.; Rodionov, R.

    2014-03-01

    The neutron efficiency of a Gas Electron Multiplier (GEM)-based detector designed for fast neutron measurements in fusion devices was determined through the combined use of Monte Carlo (MCNPX) calculations and analysis of deuterium-deuterium and deuterium-tritium neutron irradiation experiments. The detector, characterized by a triple GEM structure flushed with a Ar/CO2/CF4 - 45/15/40 gas mixture, features a digital read-out system and has two sub-units for the detection of 2.5+14 MeV neutrons and 14 MeV neutrons (UDD and UDT, respectively). The pulse height spectra (PHS) determined from the curves of experimental efficiency as a function of the detector's high voltage (HV) and the MCNPX-simulated PHS were compared using a fitting routine that finds the best match between the experimental and simulated PHS by assuming a parametric model for the relation between HV (that determines the detector's gain) and the energy deposited in the gas. This led to express the experimental neutron efficiency as a function of the discrimination level set on the deposited energy (energy threshold). The detector sensitivity to γ-rays was also analyzed and the operational range in which the γ-ray contribution to the signal is not negligible was determined. It is found that this detector can reach a maximum neutron efficiency of ~1×10-3 counts/n at 2.5 MeV (UDD sub-unit) and of ~4×10-3 counts/n at 14 MeV (UDT and UDD sub-units).

  16. Illuminant color estimation based on pigmentation separation from human skin color

    NASA Astrophysics Data System (ADS)

    Tanaka, Satomi; Kakinuma, Akihiro; Kamijo, Naohiro; Takahashi, Hiroshi; Tsumura, Norimichi

    2015-03-01

    Human has the visual system called "color constancy" that maintains the perceptive colors of same object across various light sources. The effective method of color constancy algorithm was proposed to use the human facial color in a digital color image, however, this method has wrong estimation results by the difference of individual facial colors. In this paper, we present the novel color constancy algorithm based on skin color analysis. The skin color analysis is the method to separate the skin color into the components of melanin, hemoglobin and shading. We use the stationary property of Japanese facial color, and this property is calculated from the components of melanin and hemoglobin. As a result, we achieve to propose the method to use subject's facial color in image and not depend on the individual difference among Japanese facial color.

  17. A MAPS based vertex detector for the STAR experiment at RHIC

    SciTech Connect

    Anderssen, E; Ritter, H G; Schambach, J; Sun, X; Szelezniak, M; Thomas, J; Vu, C; Wieman, H

    2011-09-11

    The STAR experiment at RHIC is in the process of upgrading the inner detector region of the experiment to improve the vertex resolution. We describe the current design of a MAPS based vertex detector, which is the innermost and highest resolution detector of the set of three planned upgrade detectors. This detector will enable the identification of decay vertices displaced from the interaction vertex by 100-150 {micro}m and extend the capabilities of the STAR detector in the heavy flavor domain. We present selected detector design characteristics and prototyping results, which help to validate the design in preparation for the construction of the detector.

  18. Characterizing LEDs for general illumination applications: mixed-color and phosphor-based white sources

    NASA Astrophysics Data System (ADS)

    Narendran, Nadarajah; Maliyagoda, Nishantha; Deng, Lei; Pysar, Richard M.

    2001-12-01

    The rapid development of high-brightness light emitting diodes (LEDs) has made this technology a potential candidate for architectural lighting applications. There are two distinct approaches for creating white light. The first is combining blue LEDs with a phosphor and the second is mixing monochromatic LEDs in appropriate proportions. This manuscript presents some of the critical issues involved in creating a good quality, stable white light source using the color mixture approach for LEDs. Some sample calculations for mixing different colored LEDs to obtain specific color appearance (CCT) and color rendering properties (CRI) are shown in this paper. Calculations show that the CRI values of mixed-color white LEDs can be changed significantly by shifting the wavelengths of the LEDs by a small amount. It is also shown that small amplitude and wavelength shifts can cause perceivable color differences in the mixed-color white LEDs. Therefore, circuits must be properly designed to power these types of white light sources so that they are acceptable for architectural lighting applications. Because the light output variation as a function of time at different drive currents was not readily available, an experiment was conducted to quantify the light output change as a function of time for red, green, blue and white 5-mm LEDs, at fiber different constant current values (20,30,40,50 and 50 mA). The light output of the different colored LEDs depreciated at different rates. The depreciation rates increased in the following order: red, green, blue, and white. Furthermore, the light output depreciation increased with increasing drive current. The red LEDs has the least amount of light output depreciation rate variation as function of drive current, green and blue LEDs ranked after that, and white LEDs had the most variation for the same drive current variation. A group of twelve new high-powered phosphor-based white LEDs were tested at their rated current, (which is much

  19. Chromaticity space for illuminant invariant recognition.

    PubMed

    Ratnasingam, Sivalogeswaran; McGinnity, T Martin

    2012-08-01

    In this paper an algorithm is proposed to extract two illuminant invariant chromaticity features from three image sensor responses. The algorithm extracts these chromaticity features at pixel level and therefore can perform well in scenes illuminated with non-uniform illuminant. An approach is proposed to use the algorithm with cameras of unknown sensitivity. The algorithm was tested for separability of perceptually similar colours under the International Commission on Illumination (CIE) standard illuminants and obtained a good performance. It was also tested for colour based object recognition by illuminating objects with typical indoor illuminants and obtained a better performance compared to other existing algorithms investigated in this paper. Finally, the algorithm was tested for skin detection invariant to illuminant, ethnic background and imaging device. In this investigation, daylight scenes under different weather conditions and scenes illuminated by typical indoor illuminants were used. The proposed algorithm gives a better skin detection performance compared to widely used standard colour spaces. Based on the results presented, the proposed illuminant invariant chromaticity space can be used for machine vision applications including illuminant invariant colour based object recognition and skin detection. PMID:22481826

  20. Block-diagonal representations for covariance-based anomalous change detectors

    SciTech Connect

    Matsekh, Anna M; Theiler, James P

    2010-01-01

    We use singular vectors of the whitened cross-covariance matrix of two hyper-spectral images and the Golub-Kahan permutations in order to obtain equivalent tridiagonal representations of the coefficient matrices for a family of covariance-based quadratic Anomalous Change Detection (ACD) algorithms. Due to the nature of the problem these tridiagonal matrices have block-diagonal structure, which we exploit to derive analytical expressions for the eigenvalues of the coefficient matrices in terms of the singular values of the whitened cross-covariance matrix. The block-diagonal structure of the matrices of the RX, Chronochrome, symmetrized Chronochrome, Whitened Total Least Squares, Hyperbolic and Subpixel Hyperbolic Anomalous Change Detectors are revealed by the white singular value decomposition and Golub-Kahan transformations. Similarities and differences in the properties of these change detectors are illuminated by their eigenvalue spectra. We presented a methodology that provides the eigenvalue spectrum for a wide range of quadratic anomalous change detectors. Table I summarizes these results, and Fig. I illustrates them. Although their eigenvalues differ, we find that RX, HACD, Subpixel HACD, symmetrized Chronochrome, and WTLSQ share the same eigenvectors. The eigen vectors for the two variants of Chronochrome defined in (18) are different, and are different from each other, even though they share many (but not all, unless d{sub x} = d{sub y}) eigenvalues. We demonstrated that it is sufficient to compute SVD of the whitened cross covariance matrix of the data in order to almost immediately obtain highly structured sparse matrices (and their eigenvalue spectra) of the coefficient matrices of these ACD algorithms in the white SVD-transformed coordinates. Converting to the original non-white coordinates, these eigenvalues will be modified in magnitude but not in sign. That is, the number of positive, zero-valued, and negative eigenvalues will be conserved.

  1. Dose Imaging Detectors for Radiotherapy Based on Gas Electron Multipliers

    PubMed Central

    Klyachko, A.V.; Friesel, D.L.; Kline, C.; Liechty, J.; Nichiporov, D.F.; Solberg, K.A.

    2010-01-01

    New techniques in charged particle therapy and widespread use of modern dynamic beam delivery systems demand new beam monitoring devices as well as accurate 2D dosimetry systems to verify the delivered dose distribution. We are developing dose imaging detectors based on gas electron multipliers (GEM) with the goal of improving dose measurement linearity, position and timing resolution, and to ultimately allow pre-treatment verification of dose distributions and dose delivery monitoring employing scanning beam technology. A prototype 10×10 cm2 double-GEM detector has been tested in the 205 MeV proton beam using electronic and optical readout modes. Preliminary results with electronic cross-strip readout demonstrate fast response and single-pixel (4 mm) position resolution. In optical readout mode, the line spread function of the detector was found to have σ=0.7 mm. In both readout modes, the detector response was linear up to dose rates of 50 Gy/min, with adequate representation of the Bragg peak in depth-dose profile measurements. PMID:21528010

  2. Super-resolution of fluorescence-free plasmonic nanoparticles using enhanced dark-field illumination based on wavelength-modulation

    DOE PAGESBeta

    Zhang, Peng; Lee, Seungah; Yu, Hyunung; Fang, Ning; Ho Kang, Seong

    2015-06-15

    Super-resolution imaging of fluorescence-free plasmonic nanoparticles (NPs) was achieved using enhanced dark-field (EDF) illumination based on wavelength-modulation. Indistinguishable adjacent EDF images of 103-nm gold nanoparticles (GNPs), 40-nm gold nanorods (GNRs), and 80-nm silver nanoparticles (SNPs) were modulated at their wavelengths of specific localized surface plasmon scattering. The coordinates (x, y) of each NP were resolved by fitting their point spread functions with a two-dimensional Gaussian. The measured localization precisions of GNPs, GNRs, and SNPs were 2.5 nm, 5.0 nm, and 2.9 nm, respectively. From the resolved coordinates of NPs and the corresponding localization precisions, super-resolution images were reconstructed. Depending onmore » the spontaneous polarization of GNR scattering, the orientation angle of GNRs in two-dimensions was resolved and provided more elaborate localization information. This novel fluorescence-free super-resolution method was applied to live HeLa cells to resolve NPs and provided remarkable subdiffraction limit images.« less

  3. Super-resolution of fluorescence-free plasmonic nanoparticles using enhanced dark-field illumination based on wavelength-modulation

    PubMed Central

    Zhang, Peng; Lee, Seungah; Yu, Hyunung; Fang, Ning; Ho Kang, Seong

    2015-01-01

    Super-resolution imaging of fluorescence-free plasmonic nanoparticles (NPs) was achieved using enhanced dark-field (EDF) illumination based on wavelength-modulation. Indistinguishable adjacent EDF images of 103-nm gold nanoparticles (GNPs), 40-nm gold nanorods (GNRs), and 80-nm silver nanoparticles (SNPs) were modulated at their wavelengths of specific localized surface plasmon scattering. The coordinates (x, y) of each NP were resolved by fitting their point spread functions with a two-dimensional Gaussian. The measured localization precisions of GNPs, GNRs, and SNPs were 2.5 nm, 5.0 nm, and 2.9 nm, respectively. From the resolved coordinates of NPs and the corresponding localization precisions, super-resolution images were reconstructed. Depending on the spontaneous polarization of GNR scattering, the orientation angle of GNRs in two-dimensions was resolved and provided more elaborate localization information. This novel fluorescence-free super-resolution method was applied to live HeLa cells to resolve NPs and provided remarkable sub-diffraction limit images. PMID:26074302

  4. Super-resolution of fluorescence-free plasmonic nanoparticles using enhanced dark-field illumination based on wavelength-modulation

    SciTech Connect

    Zhang, Peng; Lee, Seungah; Yu, Hyunung; Fang, Ning; Ho Kang, Seong

    2015-06-15

    Super-resolution imaging of fluorescence-free plasmonic nanoparticles (NPs) was achieved using enhanced dark-field (EDF) illumination based on wavelength-modulation. Indistinguishable adjacent EDF images of 103-nm gold nanoparticles (GNPs), 40-nm gold nanorods (GNRs), and 80-nm silver nanoparticles (SNPs) were modulated at their wavelengths of specific localized surface plasmon scattering. The coordinates (x, y) of each NP were resolved by fitting their point spread functions with a two-dimensional Gaussian. The measured localization precisions of GNPs, GNRs, and SNPs were 2.5 nm, 5.0 nm, and 2.9 nm, respectively. From the resolved coordinates of NPs and the corresponding localization precisions, super-resolution images were reconstructed. Depending on the spontaneous polarization of GNR scattering, the orientation angle of GNRs in two-dimensions was resolved and provided more elaborate localization information. This novel fluorescence-free super-resolution method was applied to live HeLa cells to resolve NPs and provided remarkable subdiffraction limit images.

  5. A VXIbus based trigger for the CLAS detector at CEBAF

    SciTech Connect

    Doughty, D.C. Jr.; Englert, J.; Hale, R.; Lemon, S. ); Leung, P. ); Cuevas, C.; Joyce, D. )

    1992-04-01

    This paper discusses a VXIbus based first level triggering system for the CLAS detector at CEBAF which has been designed and prototyped. It uses pipelining and a triple memory lookup to produce a dead-timeless trigger decision with an average latency of 110 ns and a jitter of 20 ns. The VXIbus Extended Start/Stop triggering protocols allow sub-nanosecond time synchronization.

  6. A VXIbus based trigger for the CLAS detector at CEBAF

    SciTech Connect

    D.C. Doughty, Jr.; J. Englert; R. Hale; S. Lemon; P. Leung; C. Cuevas; D. Joyce

    1992-04-01

    A VXIbus based first level triggering system for the CLAS detector at CEBAF has been designed and prototyped. It uses pipelining and a triple memory lookup to produce a dead-timeless trigger decision with an average latency of 110 nS and a jitter of 20 nS. The VXIbus Extended Start/Stop triggering protocols allow sub-nanosecond time synchronization.

  7. A risk-based approach to flammable gas detector spacing.

    PubMed

    Defriend, Stephen; Dejmek, Mark; Porter, Leisa; Deshotels, Bob; Natvig, Bernt

    2008-11-15

    Flammable gas detectors allow an operating company to address leaks before they become serious, by automatically alarming and by initiating isolation and safe venting. Without effective gas detection, there is very limited defense against a flammable gas leak developing into a fire or explosion that could cause loss of life or escalate to cascading failures of nearby vessels, piping, and equipment. While it is commonly recognized that some gas detectors are needed in a process plant containing flammable gas or volatile liquids, there is usually a question of how many are needed. The areas that need protection can be determined by dispersion modeling from potential leak sites. Within the areas that must be protected, the spacing of detectors (or alternatively, number of detectors) should be based on risk. Detector design can be characterized by spacing criteria, which is convenient for design - or alternatively by number of detectors, which is convenient for cost reporting. The factors that influence the risk are site-specific, including process conditions, chemical composition, number of potential leak sites, piping design standards, arrangement of plant equipment and structures, design of isolation and depressurization systems, and frequency of detector testing. Site-specific factors such as those just mentioned affect the size of flammable gas cloud that must be detected (within a specified probability) by the gas detection system. A probability of detection must be specified that gives a design with a tolerable risk of fires and explosions. To determine the optimum spacing of detectors, it is important to consider the probability that a detector will fail at some time and be inoperative until replaced or repaired. A cost-effective approach is based on the combined risk from a representative selection of leakage scenarios, rather than a worst-case evaluation. This means that probability and severity of leak consequences must be evaluated together. In marine and

  8. Multi-element double ring infrared detector based on InSb

    NASA Astrophysics Data System (ADS)

    Li, Mo; Lv, Hui; Guo, Li; Liu, Zhu

    2015-10-01

    A multi-element double ring infrared detector based on InSb p-n photodiodes is presented. The presented detector includes an outer ring detector and an inner ring detector. Each ring consist 10 detector elements, five mid-wave infrared detector elements and five short wave infrared detector elements. Two wavebands of 3.5-5 μm and 1.5-3 μm in mid-wave infrared and short wave infrared are adopted. The mid-wave infrared and short wave infrared detector elements are arranged alternately and close to each other to form detection pair. Between the adjacent detector elements, there is an interval to avoid cross talk. Dual band filter thin films are directly coated on the photodiode surface to form a dual band infrared detector. The double ring detector which can perform dual band IR counter-countermeasures can track target effectively under infrared countermeasure conditions.

  9. Advanced Fluorescence Protein-Based Synapse-Detectors

    PubMed Central

    Lee, Hojin; Oh, Won Chan; Seong, Jihye; Kim, Jinhyun

    2016-01-01

    The complex information-processing capabilities of the central nervous system emerge from intricate patterns of synaptic input-output relationships among various neuronal circuit components. Understanding these capabilities thus requires a precise description of the individual synapses that comprise neural networks. Recent advances in fluorescent protein engineering, along with developments in light-favoring tissue clearing and optical imaging techniques, have rendered light microscopy (LM) a potent candidate for large-scale analyses of synapses, their properties, and their connectivity. Optically imaging newly engineered fluorescent proteins (FPs) tagged to synaptic proteins or microstructures enables the efficient, fine-resolution illumination of synaptic anatomy and function in large neural circuits. Here we review the latest progress in fluorescent protein-based molecular tools for imaging individual synapses and synaptic connectivity. We also identify associated technologies in gene delivery, tissue processing, and computational image analysis that will play a crucial role in bridging the gap between synapse- and system-level neuroscience. PMID:27445785

  10. Advanced Fluorescence Protein-Based Synapse-Detectors.

    PubMed

    Lee, Hojin; Oh, Won Chan; Seong, Jihye; Kim, Jinhyun

    2016-01-01

    The complex information-processing capabilities of the central nervous system emerge from intricate patterns of synaptic input-output relationships among various neuronal circuit components. Understanding these capabilities thus requires a precise description of the individual synapses that comprise neural networks. Recent advances in fluorescent protein engineering, along with developments in light-favoring tissue clearing and optical imaging techniques, have rendered light microscopy (LM) a potent candidate for large-scale analyses of synapses, their properties, and their connectivity. Optically imaging newly engineered fluorescent proteins (FPs) tagged to synaptic proteins or microstructures enables the efficient, fine-resolution illumination of synaptic anatomy and function in large neural circuits. Here we review the latest progress in fluorescent protein-based molecular tools for imaging individual synapses and synaptic connectivity. We also identify associated technologies in gene delivery, tissue processing, and computational image analysis that will play a crucial role in bridging the gap between synapse- and system-level neuroscience. PMID:27445785

  11. Image plane sweep volume illumination.

    PubMed

    Sundén, Erik; Ynnerman, Anders; Ropinski, Timo

    2011-12-01

    In recent years, many volumetric illumination models have been proposed, which have the potential to simulate advanced lighting effects and thus support improved image comprehension. Although volume ray-casting is widely accepted as the volume rendering technique which achieves the highest image quality, so far no volumetric illumination algorithm has been designed to be directly incorporated into the ray-casting process. In this paper we propose image plane sweep volume illumination (IPSVI), which allows the integration of advanced illumination effects into a GPU-based volume ray-caster by exploiting the plane sweep paradigm. Thus, we are able to reduce the problem complexity and achieve interactive frame rates, while supporting scattering as well as shadowing. Since all illumination computations are performed directly within a single rendering pass, IPSVI does not require any preprocessing nor does it need to store intermediate results within an illumination volume. It therefore has a significantly lower memory footprint than other techniques. This makes IPSVI directly applicable to large data sets. Furthermore, the integration into a GPU-based ray-caster allows for high image quality as well as improved rendering performance by exploiting early ray termination. This paper discusses the theory behind IPSVI, describes its implementation, demonstrates its visual results and provides performance measurements. PMID:22034331

  12. Lunar South Pole Illumination

    NASA Video Gallery

    Simulated illumination conditions over the lunar South Pole region, from ~80°S to the pole. The movie runs for 28 days, centered on the LCROSS impact date on October 9th, 2009. The illumination ca...

  13. Fluorozirconate-based glass ceramic x-ray detectors for digital radiography.

    SciTech Connect

    Schweizer, S.; Johnson, J. A.; Energy Technology; Univ. of Paderborn

    2007-04-01

    Two-dimensional indirect digital X-ray detectors use either a storage phosphor or a scintillator as an imaging plate. A storage phosphor forms a latent X-ray image, which is subsequently readout by a photostimulable luminescence process. A scintillator produces a visible image during X-ray illumination. Commercial storage-phosphor image plates have relatively poor spatial resolution because of light scattering during the readout. To improve their image resolution, europium (II)-doped fluorozirconate (FZ)-based glasses containing barium chloride nanoparticles have been developed. X-ray imaging showed that these storage-phosphor plates can resolve features as small as 17 {micro}m. By using appropriate thermal-processing conditions, the FZ-based glass ceramics can also be made into transparent glass ceramic scintillators. Imaging tests showed that these scintillators have a spatial resolution and efficiency comparable to those of a single-crystal CdWO{sub 4} scintillator. These results demonstrate that FZ-based glass ceramics are good candidates for digital radiography, either for storage phosphor or scintillator applications.

  14. Studying inflation with future space-based gravitational wave detectors

    SciTech Connect

    Jinno, Ryusuke; Moroi, Takeo; Takahashi, Tomo E-mail: moroi@phys.s.u-tokyo.ac.jp

    2014-12-01

    Motivated by recent progress in our understanding of the B-mode polarization of cosmic microwave background (CMB), which provides important information about the inflationary gravitational waves (IGWs), we study the possibility to acquire information about the early universe using future space-based gravitational wave (GW) detectors. We perform a detailed statistical analysis to estimate how well we can determine the reheating temperature after inflation as well as the amplitude, the tensor spectral index, and the running of the inflationary gravitational waves. We discuss how the accuracies depend on noise parameters of the detector and the minimum frequency available in the analysis. Implication of such a study on the test of inflation models is also discussed.

  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. Microfabricated cantilever-based detector for molecular beam experiments

    NASA Astrophysics Data System (ADS)

    Bachels, T.; Schäfer, R.

    1998-11-01

    A low cost detector for particles in molecular beam experiments is presented which can easily be mounted in a molecular beam apparatus. The detector is based on microfabricated cantilevers, which can be employed either as single sensors or as sensor arrays. The single cantilever technique has been used to measure the absolute number of atoms coming out of a pulsed laser vaporization cluster source. The particles are detected by the shift of the thermally excited resonance frequency of the cantilever due to the cluster deposition. We have determined with the single cantilever the ratio of neutral to ionized clusters and we have investigated the cluster generation at different source conditions. In addition to this, a microfabricated cantilever array has been used to measure molecular beam profiles, which opens new possibilities for molecular beam deflection experiments.

  17. Heterodyne detection with mismatch correction based on array detector

    NASA Astrophysics Data System (ADS)

    Dong, Hongzhou; Li, Guoqiang; Yang, Ruofu; Yang, Chunping; Ao, Mingwu

    2016-07-01

    Based on an array detector, a new heterodyne detection system, which can correct the mismatches of amplitude and phase between signal and local oscillation (LO) beams, is presented in this paper. In the light of the fact that, for a heterodyne signal, there is a certain phase difference between the adjacent two samples of analog-to-digital converter (ADC), we propose to correct the spatial phase mismatch by use of the time-domain phase difference. The corrections can be realized by shifting the output sequences acquired from the detector elements in the array, and the steps of the shifting depend on the quantity of spatial phase mismatch. Numerical calculations of heterodyne efficiency are conducted to confirm the excellent performance of our system. Being different from previous works, our system needs not extra optical devices, so it provides probably an effective means to ease the problem resulted from the mismatches.

  18. Heterodyne detection with mismatch correction base on array detector

    NASA Astrophysics Data System (ADS)

    Hongzhou, Dong; Guoqiang, Li; Ruofu, Yang; Chunping, Yang; Mingwu, Ao

    2016-07-01

    Based on an array detector, a new heterodyne detection system, which can correct the mismatches of amplitude and phase between signal and local oscillation (LO) beams, is presented in this paper. In the light of the fact that, for a heterodyne signal, there is a certain phase difference between the adjacent two samples of analog-to-digital converter (ADC), we propose to correct the spatial phase mismatch by use of the time-domain phase difference. The corrections can be realized by shifting the output sequences acquired from the detector elements in the array, and the steps of the shifting depend on the quantity of spatial phase mismatch. Numerical calculations of heterodyne efficiency are conducted to confirm the excellent performance of our system. Being different from previous works, our system needs not extra optical devices, so it provides probably an effective means to ease the problem resulted from the mismatches.

  19. Undersampling Correction for Array Detector-Based Satellite Spectrometers

    NASA Technical Reports Server (NTRS)

    Chance, Kelly; Kurosu, Thomas P.; Sioris, Christopher E.

    2004-01-01

    Array detector-based instruments are now fundamental to measurements of ozone and other atmospheric trace gases from space in the ultraviolet, visible, and infrared. The present generation of such instruments suffers, to a greater or lesser degree, from undersampling of the spectra, leading to difficulties in the analysis of atmospheric radiances. We provide extended analysis of the undersampling suffered by modem satellite spectrometers, which include Global Ozone Monitoring Experiment (GOME), Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), Ozone Monitoring Instrument (OMI), and Ozone Mapping and Profiler Suite (OMPS). The analysis includes basic undersampling, the effects of binning into separate detector pixels, and the application of high-resolution Fraunhofer spectral data to correct for undersampling in many useful cases.

  20. Prototype of a large neutron detector based on MWPC

    NASA Astrophysics Data System (ADS)

    Tian, LiChao; Qi, HuiRong; Sun, ZhiJia; Wang, YanFeng; Zhang, Jian; Liu, RongGuang; Zhao, YuBin; Zhang, HongYu; Zhao, DongXu; Dong, Jing; Xie, Wan; Yang, GuiAn; Ouyang, Qun; Chen, YuanBo

    2014-11-01

    A prototype of large-area position sensitive neutron detector was designed and constructed according to the requirements of the Small-Angle Scattering spectrometer of China Spallation Neutron Source (CSNS). The detector was based on the 3He neutron convertor and MWPC with an effective area of 650 mm×650 mm. A prototype was completed and tested with 55Fe X-ray.The high-pressure vessel was designed and constructed with high-strength aluminum alloy. A position resolution of about 4.6 mm×2.3 mm (FWHM) and efficiency > 65% for neutrons with wavelength of 1.8 Å was determined after the operational gas filled.

  1. Lights illuminate surfaces superluminally

    NASA Astrophysics Data System (ADS)

    Nemiroff, Robert J.; Zhong, Qi; Lilleskov, Elias

    2016-07-01

    When a light bulb is turned on, light moves away from it at speed c, by definition. When light from this bulb illuminates a surface, however, this illumination front is not constrained to move at speed c. A simple proof is given that this illumination front always moves faster than c. Generalized, when any compact light source itself varies, this information spreads across all of the surfaces it illuminates at speeds faster than light.

  2. Optical sensors based on the molecular condensation nuclei detector

    NASA Astrophysics Data System (ADS)

    Kuptsov, Vladimir D.; Katelevsky, Vadim Y.; Valyukhov, Vladimir P.

    2015-05-01

    Molecular condensation nuclei (MCN) detector is a specialized optical sensor which provides for monitoring of various chemicals impurity in the environment and diagnosis of diseases in human exhaled air ("electronic nose" biosensor). Structurally MCN detector is included in the highly sensitive gas analyzers based on MCN method. The article describes the fundamental principles, specific features and application fields of the advanced highly sensitive MCN method. The MCN method is based on the application of various physico-chemical processes to the flow of a gas containing impurities. As a result of these processes aerosol particle that are about 106 times larger than the original molecule of the impurity are produced. The ability of the aerosol particle to scatter incident light also increases ~1014÷1016 times compared with the original molecule and the aerosol particle with the molecule of the impurity in the center is easily detected by light scattering inside a photometer. By measuring of the light scattering intensity is determined concentration of chemical impurities in the air. Aerosol particles in the MCN detector are formed in the condensing devices through overgrowth of the molecule detectable impurity by molecules so-called «developer» substance. At the final stage of the analysis in the MCN detector is measured light scattering by aerosol particles which is proportional to the concentration of determined impurities in the environment. For calculations of the scattered radiation is applicable Mie's theory considering the scattering of light by spherical particles whose size is comparable to the wavelength of light. We have determined that the light scattering by aerosol particles is interferometric and is comparable within an order of magnitude with light scattering by the air inside a photometer. The detection threshold for the target component of the gas analyzer is attained at the spontaneous ionization background level and not at the limiting

  3. SENTIRAD—An innovative personal radiation detector based on a scintillation detector and a silicon photomultiplier

    NASA Astrophysics Data System (ADS)

    Osovizky, A.; Ginzburg, D.; Manor, A.; Seif, R.; Ghelman, M.; Cohen-Zada, I.; Ellenbogen, M.; Bronfenmakher, V.; Pushkarsky, V.; Gonen, E.; Mazor, T.; Cohen, Y.

    2011-10-01

    The alarming personal radiation detector (PRD) is a device intended for Homeland Security (HLS) applications. This portable device is designed to be worn or carried by security personnel to detect photon-emitting radioactive materials for the purpose of crime prevention. PRD is required to meet the scope of specifications defined by various HLS standards for radiation detection. It is mandatory that the device be sensitive and simultaneously small, pocket-sized, of robust mechanical design and carriable on the user's body. To serve these specialized purposes and requirements, we developed the SENTIRAD, a new radiation detector designed to meet the performance criteria established for counterterrorist applications. SENTIRAD is the first commercially available PRD based on a CsI(Tl) scintillation crystal that is optically coupled with a silicon photomultiplier (SiPM) serving as a light sensor. The rapidly developing technology of SiPM, a multipixel semiconductor photodiode that operates in Geiger mode, has been thoroughly investigated in previous studies. This paper presents the design considerations, constraints and radiological performance relating to the SENTIRAD radiation sensor.

  4. Illumination pupilgram control using an intelligent illuminator

    NASA Astrophysics Data System (ADS)

    Hirayanagi, Noriyuki; Mizuno, Yasushi; Mori, Masakazu; Kita, Naonori; Matsui, Ryota; Matsuyama, Tomoyuki

    2013-04-01

    Nikon's Intelligent Illuminator, a freeform pupilgram generator, realizes a high flexibility for pupilgram control by using more than 10,000 degrees-of-freedom for pupilgram adjustment. In this work, an Intelligent Illuminator was integrated into an ArF scanner, the Nikon NSR-S621D. We demonstrate the pupilgram setting accuracy by direct correlation between on-body measured pupilgram and desired target pupilgram. We show that the Intelligent Illuminator is used for fine tuning of the pupilgram to match optical proximity effect (OPE) characteristics. We experimentally confirmed that a global source optimization software realized an improvement of lithographic process window without changing OPE characteristics by using optimized pupilgram made by Intelligent Illuminator.

  5. Front-side illuminated CdS/CdSe quantum dots co-sensitized solar cells based on TiO2 nanotube arrays

    NASA Astrophysics Data System (ADS)

    Guan, Xiao-Fang; Huang, Shu-Qing; Zhang, Quan-Xin; Shen, Xi; Sun, Hui-Cheng; Li, Dong-Mei; Luo, Yan-Hong; Yu, Ri-Cheng; Meng, Qing-Bo

    2011-11-01

    We fabricated a front-side illuminated CdS/CdSe quantum dots co-sensitized solar cell based on TiO2 nanotube arrays. The freestanding TiO2 nanotube arrays were first detached from anodic oxidized Ti foils and then transferred to the fluorine-doped tin oxide to form photoanodes. An opaque Cu2S with high electrochemical activity was used as the counter electrode. A photovoltaic conversion efficiency as high as 3.01% under one sun illumination has been achieved after optimizing the deposition time of CdSe quantum dots and the length of the TiO2 nanotube arrays. It is observed that the power conversion efficiency of quantum dots sensitized solar cells from the front-side illumination mode (3.01%) is much higher than that of the back-side illumination mode (1.32%) owing to the poor catalytic activity of Pt to polysulfide electrolytes and light absorption by the electrolytes for the latter.

  6. Large area radiation detectors based on II VI thin films

    NASA Astrophysics Data System (ADS)

    Quevedo-Lopez, Manuel

    2015-03-01

    The development of low temperature device technologies that have enabled flexible displays also present opportunities for flexible electronics and flexible integrated systems. Of particular interest are possible applications in flexible, low metal content, sensor systems for unattended ground sensors, smart medical bandages, electronic ID tags for geo-location, conformal antennas, neutron/gamma-ray/x-ray detectors, etc. In this talk, our efforts to develop novel CMOS integration schemes, circuits, memory, sensors as well as novel contacts, dielectrics and semiconductors for flexible electronics are presented. In particular, in this presentation we discuss fundamental materials properties including crystalline structure, interfacial reactions, doping, etc. defining performance and reliability of II-VI-based radiation sensors. We investigate the optimal thickness of a semiconductor diode for thin-film solid state thermal neutron detectors. Besides II-VI materials, we also evaluated several diode materials, Si, CdTe,GaAs, C (diamond), and ZnO, and two neutron converter materials,10B and 6LiF. We determine the minimum semiconductor thickness needed to achieve maximum neutron detection efficiency. By keeping the semiconductor thickness to a minimum, gamma rejection is kept as high as possible. In this way, we optimize detector performance for different thin-film semiconductor materials.

  7. The Effect of Personalization on Smartphone-Based Fall Detectors.

    PubMed

    Medrano, Carlos; Plaza, Inmaculada; Igual, Raúl; Sánchez, Ángel; Castro, Manuel

    2016-01-01

    The risk of falling is high among different groups of people, such as older people, individuals with Parkinson's disease or patients in neuro-rehabilitation units. Developing robust fall detectors is important for acting promptly in case of a fall. Therefore, in this study we propose to personalize smartphone-based detectors to boost their performance as compared to a non-personalized system. Four algorithms were investigated using a public dataset: three novelty detection algorithms--Nearest Neighbor (NN), Local Outlier Factor (LOF) and One-Class Support Vector Machine (OneClass-SVM)--and a traditional supervised algorithm, Support Vector Machine (SVM). The effect of personalization was studied for each subject by considering two different training conditions: data coming only from that subject or data coming from the remaining subjects. The area under the receiver operating characteristic curve (AUC) was selected as the primary figure of merit. The results show that there is a general trend towards the increase in performance by personalizing the detector, but the effect depends on the individual being considered. A personalized NN can reach the performance of a non-personalized SVM (average AUC of 0.9861 and 0.9795, respectively), which is remarkable since NN only uses activities of daily living for training. PMID:26797614

  8. The Effect of Personalization on Smartphone-Based Fall Detectors

    PubMed Central

    Medrano, Carlos; Plaza, Inmaculada; Igual, Raúl; Sánchez, Ángel; Castro, Manuel

    2016-01-01

    The risk of falling is high among different groups of people, such as older people, individuals with Parkinson's disease or patients in neuro-rehabilitation units. Developing robust fall detectors is important for acting promptly in case of a fall. Therefore, in this study we propose to personalize smartphone-based detectors to boost their performance as compared to a non-personalized system. Four algorithms were investigated using a public dataset: three novelty detection algorithms—Nearest Neighbor (NN), Local Outlier Factor (LOF) and One-Class Support Vector Machine (OneClass-SVM)—and a traditional supervised algorithm, Support Vector Machine (SVM). The effect of personalization was studied for each subject by considering two different training conditions: data coming only from that subject or data coming from the remaining subjects. The area under the receiver operating characteristic curve (AUC) was selected as the primary figure of merit. The results show that there is a general trend towards the increase in performance by personalizing the detector, but the effect depends on the individual being considered. A personalized NN can reach the performance of a non-personalized SVM (average AUC of 0.9861 and 0.9795, respectively), which is remarkable since NN only uses activities of daily living for training. PMID:26797614

  9. Advanced mask aligner lithography: new illumination system.

    PubMed

    Voelkel, Reinhard; Vogler, Uwe; Bich, Andreas; Pernet, Pascal; Weible, Kenneth J; Hornung, Michael; Zoberbier, Ralph; Cullmann, Elmar; Stuerzebecher, Lorenz; Harzendorf, Torsten; Zeitner, Uwe D

    2010-09-27

    A new illumination system for mask aligner lithography is presented. The illumination system uses two subsequent microlens-based Köhler integrators. The second Köhler integrator is located in the Fourier plane of the first. The new illumination system uncouples the illumination light from the light source and provides excellent uniformity of the light irradiance and the angular spectrum. Spatial filtering allows to freely shape the angular spectrum to minimize diffraction effects in contact and proximity lithography. Telecentric illumination and ability to precisely control the illumination light allows to introduce resolution enhancement technologies (RET) like customized illumination, optical proximity correction (OPC) and source-mask optimization (SMO) in mask aligner lithography. PMID:20940992

  10. Application of Wireless Intelligent Control System for HPS Lamps and LEDs Combined Illumination in Road Tunnel

    PubMed Central

    Lai, Jinxing; Qiu, Junling; Chen, Jianxun; Wang, Yaqiong; Fan, Haobo

    2014-01-01

    Because of the particularity of the environment in the tunnel, the rational tunnel illumination system should be developed, so as to optimize the tunnel environment. Considering the high cost of traditional tunnel illumination system with high-pressure sodium (HPS) lamps as well as the effect of a single light source on tunnel entrance, the energy-saving illumination system with HPS lamps and LEDs combined illumination in road tunnel, which could make full use of these two kinds of lamps, was proposed. The wireless intelligent control system based on HPS lamps and LEDs combined illumination and microcontrol unit (MCU) Si1000 wireless communication technology was designed. And the remote monitoring, wireless communication, and PWM dimming module of this system were designed emphatically. Intensity detector and vehicle flow detector can be configured in wireless intelligent control system, which gather the information to the master control unit, and then the information is sent to the monitoring center through the Ethernet. The control strategies are got by the monitoring center according to the calculated results, and the control unit wirelessly sends parameters to lamps, which adjust the luminance of each segment of the tunnel and realize the wireless intelligent control of combined illumination in road tunnel. PMID:25587266

  11. Shortwave infrared for night vision applications: illumination levels and sensor performance

    NASA Astrophysics Data System (ADS)

    Adomeit, Uwe; Krieg, Jürgen

    2015-10-01

    Radiation created by stimulation and recombination/deactivation of atoms and molecules in the higher earth atmosphere is called nightglow. This nightglow can be found in the spectral range from the ultraviolet up to the thermal infrared, with a maximum in the shortwave infrared (SWIR). During moonless nights the illumination in the SWIR is by an order of magnitude higher than the visual one. Within the last years the SWIR sensor technology improved to a level of using the nightglow for night vision applications. This necessitates understanding of the highly variable illumination levels created by the nightglow and the performance assessment of the SWIR detectors in comparison to the image intensifiers respectively Si focal plane array detectors. Whereas the night illumination levels for the visual are standardized, corresponding ones for the SWIR are missing. IOSB started measuring and comparing night illumination levels and camera performance in both spectral ranges based on continuous illumination measurements as well as recording imagery of reflectance reference targets with cameras and analyzing the resulting signal-to-noise ratios. To date the number of illumination measurements are not yet statistically sufficient to standardize the levels, but at least allowed a first comparison of the two technologies for moonless night, clear sky conditions. With comparable F-number, integration time and frame rate, the SWIR sensors available in Europe were found to be inferior to the visual technology. An improvement of at least one magnitude would be necessary to ensure similarity between SWIR and visual technologies for all environmental conditions.

  12. Application of wireless intelligent control system for HPS lamps and LEDs combined illumination in road tunnel.

    PubMed

    Lai, Jinxing; Qiu, Junling; Chen, Jianxun; Wang, Yaqiong; Fan, Haobo

    2014-01-01

    Because of the particularity of the environment in the tunnel, the rational tunnel illumination system should be developed, so as to optimize the tunnel environment. Considering the high cost of traditional tunnel illumination system with high-pressure sodium (HPS) lamps as well as the effect of a single light source on tunnel entrance, the energy-saving illumination system with HPS lamps and LEDs combined illumination in road tunnel, which could make full use of these two kinds of lamps, was proposed. The wireless intelligent control system based on HPS lamps and LEDs combined illumination and microcontrol unit (MCU) Si1000 wireless communication technology was designed. And the remote monitoring, wireless communication, and PWM dimming module of this system were designed emphatically. Intensity detector and vehicle flow detector can be configured in wireless intelligent control system, which gather the information to the master control unit, and then the information is sent to the monitoring center through the Ethernet. The control strategies are got by the monitoring center according to the calculated results, and the control unit wirelessly sends parameters to lamps, which adjust the luminance of each segment of the tunnel and realize the wireless intelligent control of combined illumination in road tunnel. PMID:25587266

  13. The MAPS based PXL vertex detector for the STAR experiment

    NASA Astrophysics Data System (ADS)

    Contin, G.; Anderssen, E.; Greiner, L.; Schambach, J.; Silber, J.; Stezelberger, T.; Sun, X.; Szelezniak, M.; Vu, C.; Wieman, H.; Woodmansee, S.

    2015-03-01

    The Heavy Flavor Tracker (HFT) was installed in the STAR experiment for the 2014 heavy ion run of RHIC. Designed to improve the vertex resolution and extend the measurement capabilities in the heavy flavor domain, the HFT is composed of three different silicon detectors based on CMOS monolithic active pixels (MAPS), pads and strips respectively, arranged in four concentric cylinders close to the STAR interaction point. The two innermost HFT layers are placed at a radius of 2.7 and 8 cm from the beam line, respectively, and accommodate 400 ultra-thin (50 μ m) high resolution MAPS sensors arranged in 10-sensor ladders to cover a total silicon area of 0.16 m2. Each sensor includes a pixel array of 928 rows and 960 columns with a 20.7 μ m pixel pitch, providing a sensitive area of ~ 3.8 cm2. The architecture is based on a column parallel readout with amplification and correlated double sampling inside each pixel. Each column is terminated with a high precision discriminator, is read out in a rolling shutter mode and the output is processed through an integrated zero suppression logic. The results are stored in two SRAM with ping-pong arrangement for a continuous readout. The sensor features 185.6 μ s readout time and 170 mW/cm2 power dissipation. The detector is air-cooled, allowing a global material budget as low as 0.39% on the inner layer. A novel mechanical approach to detector insertion enables effective installation and integration of the pixel layers within an 8 hour shift during the on-going STAR run.In addition to a detailed description of the detector characteristics, the experience of the first months of data taking will be presented in this paper, with a particular focus on sensor threshold calibration, latch-up protection procedures and general system operations aimed at stabilizing the running conditions. Issues faced during the 2014 run will be discussed together with the implemented solutions. A preliminary analysis of the detector performance

  14. Data analysis for space-based gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Crowder, Jefferson Osborn

    With the launch of the Laser Interferometer Space Antenna (LISA) expected for the next decade, the nascent field of gravitational wave astronomy will be taking a giant leap forward. The data that will be gathered from space-borne gravitational wave detectors such as LISA will provide an expansive look through a new window on the Universe. This dissertation is presented to help open that window by exploring some of the techniques and methods that will be needed to understand the data from these detectors. The first original work presented here investigates the resolution of LISA and follow-on space-based gravitational wave missions. This work presents the methods of measuring the precision of these detectors and gives results for their resolving power for a large class of expected gravitational wave sources. The second original investigation involves the effect that multiple gravitational wave sources will have on the resolution of LISA. Previous results concerning detector resolution were limited to isolated sources of gravitational waves. As LISA is an all-sky detector, it is necessary to understand the role played by concurrent detection of numerous sources. This work derives an extension of the Fisher Information Matrix approach for determining parameter resolution, and applies it to multiple sources for LISA. The next original work is an exploration of the method of genetic algorithms on the problem of extracting the binary parameters of gravitational wave sources from the LISA data stream. These are global algorithms providing a means to cover the entire search space of parameter values. This work describes the basics of and provides the results for such genetic algorithm-based searches, with a focus on improving algorithm efficiency. The last original work included is a study of Markov Chain Monte Carlo (MCMC) methods applied to parameter extraction of gravitational wave sources in the LISA data stream. This work shows how an MCMC approach provides a global

  15. Photon-Noise Limited Direct Detector Based on Disorder-Controlled Electron Heating

    NASA Technical Reports Server (NTRS)

    Karasik, B.; McGrath, W.; Gershenson, M.; Sergeev, A.

    1999-01-01

    We present a new concept for a hot-electron direct detector (HEDD) capable of counting single millimeter-wave photons. The detector is based on a transition edge sensor (1-meu size bridge) made form a disordered superconducting film.

  16. Imaging performance of amorphous selenium based flat-panel detectors for digital mammography: characterization of a small area prototype detector.

    PubMed

    Zhao, Wei; Ji, W G; Debrie, Anne; Rowlands, J A

    2003-02-01

    Our work is to investigate and understand the factors affecting the imaging performance of amorphous selenium (a-Se) flat-panel detectors for digital mammography. Both theoretical and experimental methods were developed to investigate the spatial frequency dependent detective quantum efficiency [DQE(f)] of a-Se flat-panel detectors for digital mammography. Since the K edge of a-Se is 12.66 keV and within the energy range of a mammographic spectrum, a theoretical model was developed based on cascaded linear system analysis with parallel processes to take into account the effect of K fluorescence on the modulation transfer function (MTF), noise power spectrum (NPS), and DQE(f) of the detector. This model was used to understand the performance of a small-area prototype detector with 85 microm pixel size. The presampling MTF, NPS, and DQE(f) of the prototype were measured, and compared to the theoretical calculation of the model. The calculation showed that K fluorescence accounted for a 15% reduction in the MTF at the Nyquist frequency (fNy) of the prototype detector, and the NPS at fNy was reduced to 89% of that at zero spatial frequency. The measurement of presampling MTF of the prototype detector revealed an additional source of blurring, which was attributed to charge trapping in the blocking layer at the interface between a-Se and the active matrix. This introduced a drop in both presampling MTF and NPS at high spatial frequency, and reduced aliasing in the NPS. As a result, the DQE(f) of the prototype detector at fNy approached 40% of that at zero spatial frequency. The measured and calculated DQE(f) using the linear system model have reasonable agreement, indicating that the factors controlling image quality in a-Se based mammographic detectors are fully understood, and the model can be used to further optimize detector imaging performance. PMID:12607843

  17. Micro flame-based detector suite for universal gas sensing.

    SciTech Connect

    Hamilton, Thomas Warren; Washburn, Cody M.; Moorman, Matthew Wallace; Manley, Robert George; Lewis, Patrick Raymond; Miller, James Edward; Clem, Paul Gilbert; Shelmidine, Gregory J.; Manginell, Ronald Paul; Okandan, Murat

    2005-11-01

    A microflame-based detector suit has been developed for sensing of a broad range of chemical analytes. This detector combines calorimetry, flame ionization detection (FID), nitrogen-phosphorous detection (NPD) and flame photometric detection (FPD) modes into one convenient platform based on a microcombustor. The microcombustor consists in a micromachined microhotplate with a catalyst or low-work function material added to its surface. For the NPD mode a low work function material selectively ionizes chemical analytes; for all other modes a supported catalyst such as platinum/alumina is used. The microcombustor design permits rapid, efficient heating of the deposited film at low power. To perform calorimetric detection of analytes, the change in power required to maintain the resistive microhotplate heater at a constant temperature is measured. For FID and NPD modes, electrodes are placed around the microcombustor flame zone and an electrometer circuit measures the production of ions. For FPD, the flame zone is optically interrogated to search for light emission indicative of deexcitation of flame-produced analyte compounds. The calorimetric and FID modes respond generally to all hydrocarbons, while sulfur compounds only alarm in the calorimetric mode, providing speciation. The NPD mode provides 10,000:1 selectivity of nitrogen and phosphorous compounds over hydrocarbons. The FPD can distinguish between sulfur and phosphorous compounds. Importantly all detection modes can be established on one convenient microcombustor platform, in fact the calorimetric, FID and FPD modes can be achieved simultaneously on only one microcombustor. Therefore, it is possible to make a very universal chemical detector array with as little as two microcombustor elements. A demonstration of the performance of the microcombustor in each of the detection modes is provided herein.

  18. Optimizing timing performance of silicon photomultiplier-based scintillation detectors

    PubMed Central

    Yeom, Jung Yeol; Vinke, Ruud

    2013-01-01

    Precise timing resolution is crucial for applications requiring photon time-of-flight (ToF) information such as ToF positron emission tomography (PET). Silicon photomultipliers (SiPM) for PET, with their high output capacitance, are known to require custom preamplifiers to optimize timing performance. In this paper, we describe simple alternative front-end electronics based on a commercial low-noise RF preamplifier and methods that have been implemented to achieve excellent timing resolution. Two radiation detectors with L(Y)SO scintillators coupled to Hamamatsu SiPMs (MPPC S10362–33-050C) and front-end electronics based on an RF amplifier (MAR-3SM+), typically used for wireless applications that require minimal additional circuitry, have been fabricated. These detectors were used to detect annihilation photons from a Ge-68 source and the output signals were subsequently digitized by a high speed oscilloscope for offline processing. A coincident resolving time (CRT) of 147 ± 3 ps FWHM and 186 ± 3 ps FWHM with 3 × 3 × 5 mm3 and with 3 × 3 × 20 mm3 LYSO crystal elements were measured, respectively. With smaller 2 × 2 × 3 mm3 LSO crystals, a CRT of 125 ± 2 ps FWHM was achieved with slight improvement to 121 ± 3 ps at a lower temperature (15°C). Finally, with the 20 mm length crystals, a degradation of timing resolution was observed for annihilation photon interactions that occur close to the photosensor compared to shallow depth-of-interaction (DOI). We conclude that commercial RF amplifiers optimized for noise, besides their ease of use, can produce excellent timing resolution comparable to best reported values acquired with custom readout electronics. On the other hand, as timing performance degrades with increasing photon DOI, a head-on detector configuration will produce better CRT than a side-irradiated setup for longer crystals. PMID:23369872

  19. Compressive spectral imaging systems based on linear detector

    NASA Astrophysics Data System (ADS)

    Liu, Yanli; Zhong, Xiaoming; Zhao, Haibo; Li, Huan

    2015-08-01

    The spectrometers capture large amount of raw and 3-dimensional (3D) spatial-spectral scene information with 2- dimensional (2D) focal plane arrays(FPA). In many applications, including imaging system and video cameras, the Nyquist rate is so high that too many samples result, making compression a precondition to storage or transmission. Compressive sensing theory employs non-adaptive linear projections that preserve the structure of the signal, the signal is then reconstructed from these projections using an optimization process. This article overview the fundamental spectral imagers based on compressive sensing, the coded aperture snapshot spectral imagers (CASSI) and high-resolution imagers via moving random exposure. Besides that, the article propose a new method to implement spectral imagers with linear detector imager systems based on spectrum compressed. The article describes the system introduction and code process, and it illustrates results with real data and imagery. Simulations are shown to illustrate the performance improvement attained by the new model and complexity of the imaging system greatly reduced by using linear detector.

  20. Development of a soil detector based on an optical sensor

    NASA Astrophysics Data System (ADS)

    Zheng, Lihua; Pan, Luan; Li, Minzan; An, Xiaofei

    2008-12-01

    An estimation model of the soil organic matter content has been built based on NIR spectroscopy and a portable soil organic matter detector based on optical sensor is developed. The detector uses a micro processor 89S52 as the Micro Controller Unit (MCU) and consists of an optical system and a control system. The optical system includes a 850nm near-infrared lamp-house, a lamp-house driving-circuit, a Y type optical fiber, a probe, and a photoelectric sensor. The control system includes an amplified circuit, an A/D circuit, a display circuit with LCD, and a storage circuit with USB interface. Firstly the single waveband optical signal from the near-infrared lamp-house is transferred to the surface of the target soil via the incidence fibers. Then the reflected optical signal is collected and transferred to photoelectric sensor, where the optical signal is conveyed to the electrical signal. Subsequently, the obtained electrical signal is processed by 89S52 MCU. Finally, the calculated soil organic matter content is displayed on the LCD and stored in the USB disk. The calibration experiment using the estimation model of the soil organic matter is conducted. The decision coefficient (R2) reaches 0.9839 between the measured data by the soil organic matter sensor and by the laboratory chemistry method.

  1. Atmospheric Neutron Measurements using a Small Scintillator Based Detector

    NASA Astrophysics Data System (ADS)

    Kole, Merlin; Pearce, Mark; Fukazawa, Yasushi; Fukuda, Kentaro; Ishizu, Sumito; Jackson, Miranda; Kamae, Tune; Kawaguchi, Noriaki; Kawano, Takafumi; Kiss, Mozsi; Moretti, Elena; Yanagida, Takayuki; Chauvin, Maxime; Mikhalev, Victor; Rydstrom, Stefan; Takahashi, Hiromitsu

    PoGOLino is a standalone scintillator-based neutron detector designed for balloon-borne missions. Its main purpose is to provide data of the neutron flux in 2 different energy ranges in the high altitude / high latitude region where the highest neutron flux in the atmosphere is found. Furthermore the influence of the Solar activity upon the neutron environment in this region is relatively strong. As a result both short and long term time fluctuations are strongest in this region. At high altitudes neutrons can form a source of background for balloon-borne scientific measurements. They can furthermore form a major source for single event upsets in electronics. A good understanding of the high altitude / high latitude neutron environment is therefore important. Measurements of the neutron environment in this region are however lacking. PoGOLino contains two 5 mm thick Lithium Calcium Aluminium Fluoride (LiCAF) scintillators used for neutron detection. The LiCAF crystals are sandwiched between 2 Bismuth Germanium Oxide (BGO) scintillating crystals, which serve to veto signals produced by gamma-rays and charged particles. The veto system makes measurements of the neutron flux possible even in high radiation environments. One LiCAF detector is shielded with polyethylene while the second remains unshielded, making the detectors sensitive in different energy ranges. The choice of a scintillator crystals as the detection material ensures a high detection efficiency while keeping the instrument small, robust and light weight. The full standalone cylindrical instrument has a radius of 120 mm, a height of 670 mm and a total mass of 13 kg, making it suitable as a piggy back mission. PoGOLino was successfully launched on March 20th 2013 from the Esrange Space Center in Northern Sweden to an altitude of 30.9 km. A detailed description of the detector design is presented, along with results of of the flight. The neutron flux measured during flight is compared to predictions based

  2. Fast, high-contrast imaging of animal development with scanned light sheet-based structured-illumination microscopy.

    PubMed

    Keller, Philipp J; Schmidt, Annette D; Santella, Anthony; Khairy, Khaled; Bao, Zhirong; Wittbrodt, Joachim; Stelzer, Ernst H K

    2010-08-01

    Recording light-microscopy images of large, nontransparent specimens, such as developing multicellular organisms, is complicated by decreased contrast resulting from light scattering. Early zebrafish development can be captured by standard light-sheet microscopy, but new imaging strategies are required to obtain high-quality data of late development or of less transparent organisms. We combined digital scanned laser light-sheet fluorescence microscopy with incoherent structured-illumination microscopy (DSLM-SI) and created structured-illumination patterns with continuously adjustable frequencies. Our method discriminates the specimen-related scattered background from signal fluorescence, thereby removing out-of-focus light and optimizing the contrast of in-focus structures. DSLM-SI provides rapid control of the illumination pattern, exceptional imaging quality and high imaging speeds. We performed long-term imaging of zebrafish development for 58 h and fast multiple-view imaging of early Drosophila melanogaster development. We reconstructed cell positions over time from the Drosophila DSLM-SI data and created a fly digital embryo. PMID:20601950

  3. Prototype of a porous ZnO SPV-based sensor for PCB detection at room temperature under visible light illumination.

    PubMed

    Li, Mingtao; Meng, Guowen; Huang, Qing; Yin, Zhijun; Wu, Mingzai; Zhang, Zhuo; Kong, Mingguang

    2010-08-17

    To detect polychlorinated biphenyls (PCBs), a prototype of a porous ZnO sensor based on the surface photovoltage (SPV) mechanism working under visible light illumination at room temperature has been presented. The SPV of the porous ZnO sensor can be remarkably reduced under visible light illumination after PCB adsorption, and the reduction of amplitude is proportional to the population of adsorbed PCB molecules. We propose that the reduction of SPV response is due to trapping of the electrons in the surface states by the adsorbed PCBs. The lower detection limits of this new prototype sensor reach at least 2.2 micromol/L for PCB29 and 1.1 micromol/L for PCB101, respectively. So, it demonstrates great potential for practical application in trace detection of PCBs. PMID:20695623

  4. Accelerometer-Based Event Detector for Low-Power Applications

    PubMed Central

    Smidla, József; Simon, Gyula

    2013-01-01

    In this paper, an adaptive, autocovariance-based event detection algorithm is proposed, which can be used with micro-electro-mechanical systems (MEMS) accelerometer sensors to build inexpensive and power efficient event detectors. The algorithm works well with low signal-to-noise ratio input signals, and its computational complexity is very low, allowing its utilization on inexpensive low-end embedded sensor devices. The proposed algorithm decreases its energy consumption by lowering its duty cycle, as much as the event to be detected allows it. The performance of the algorithm is tested and compared to the conventional filter-based approach. The comparison was performed in an application where illegal entering of vehicles into restricted areas was detected. PMID:24135991

  5. Modulator based high bandwidth optical readout for HEP detectors

    NASA Astrophysics Data System (ADS)

    Drake, G.; Fernando, W. S.; Stanek, R. W.; Underwood, D. G.

    2013-02-01

    Optical links will be an integral part of future LHC experiments at various scales from coupled sensors to off-detector communication. We are investigating CW lasers and light modulators as an alternative to VCSELs. Light modulators are small, use less power, have high bandwidth, are reliable, have low bit error rates and are very rad-hard. We present the quality of the links at 10Gbps and the results of radiation hardness measurements for the modulators built based on LiNbO3, InP, and Si. Also we present results on modulator-based free space data links, steered by MEMS mirrors and optical feedback paths for the control loop.

  6. Advantages of gated silicon single photon detectors

    NASA Astrophysics Data System (ADS)

    Legré, Matthieu; Lunghi, Tommaso; Stucki, Damien; Zbinden, Hugo

    2013-05-01

    We present gated silicon single photon detectors based on two commercially available avalanche photodiodes (APDs) and one customised APD from ID Quantique SA. This customised APD is used in a commercially available device called id110. A brief comparison of the two commercial APDs is presented. Then, the charge persistence effect of all of those detectors that occurs just after a strong illumination is shown and discussed.

  7. Time-based position estimation in monolithic scintillator detectors.

    PubMed

    Tabacchini, Valerio; Borghi, Giacomo; Schaart, Dennis R

    2015-07-21

    Gamma-ray detectors based on bright monolithic scintillation crystals coupled to pixelated photodetectors are currently being considered for several applications in the medical imaging field. In a typical monolithic detector, both the light intensity and the time of arrival of the earliest scintillation photons can be recorded by each of the photosensor pixels every time a gamma interaction occurs. Generally, the time stamps are used to determine the gamma interaction time while the light intensities are used to estimate the 3D position of the interaction point. In this work we show that the spatio-temporal distribution of the time stamps also carries information on the location of the gamma interaction point and thus the time stamps can be used as explanatory variables for position estimation. We present a model for the spatial resolution obtainable when the interaction position is estimated using exclusively the time stamp of the first photon detected on each of the photosensor pixels. The model is shown to be in agreement with experimental measurements on a 16 mm  ×  16 mm  ×  10 mm LSO : Ce,0.2%Ca crystal coupled to a digital photon counter (DPC) array where a spatial resolution of 3 mm (root mean squared error) is obtained. Finally we discuss the effects of the main parameters such as scintillator rise and decay time, light output and photosensor single photon time resolution and pixel size. PMID:26133784

  8. Time-based position estimation in monolithic scintillator detectors

    NASA Astrophysics Data System (ADS)

    Tabacchini, Valerio; Borghi, Giacomo; Schaart, Dennis R.

    2015-07-01

    Gamma-ray detectors based on bright monolithic scintillation crystals coupled to pixelated photodetectors are currently being considered for several applications in the medical imaging field. In a typical monolithic detector, both the light intensity and the time of arrival of the earliest scintillation photons can be recorded by each of the photosensor pixels every time a gamma interaction occurs. Generally, the time stamps are used to determine the gamma interaction time while the light intensities are used to estimate the 3D position of the interaction point. In this work we show that the spatio-temporal distribution of the time stamps also carries information on the location of the gamma interaction point and thus the time stamps can be used as explanatory variables for position estimation. We present a model for the spatial resolution obtainable when the interaction position is estimated using exclusively the time stamp of the first photon detected on each of the photosensor pixels. The model is shown to be in agreement with experimental measurements on a 16 mm  ×  16 mm  ×  10 mm LSO : Ce,0.2%Ca crystal coupled to a digital photon counter (DPC) array where a spatial resolution of 3 mm (root mean squared error) is obtained. Finally we discuss the effects of the main parameters such as scintillator rise and decay time, light output and photosensor single photon time resolution and pixel size.

  9. Illicit material detector based on gas sensors and neural networks

    NASA Astrophysics Data System (ADS)

    Grimaldi, Vincent; Politano, Jean-Luc

    1997-02-01

    In accordance with its missions, le Centre de Recherches et d'Etudes de la Logistique de la Police Nationale francaise (CREL) has been conducting research for the past few years targeted at detecting drugs and explosives. We have focused our approach of the underlying physical and chemical detection principles on solid state gas sensors, in the hope of developing a hand-held drugs and explosives detector. The CREL and Laboratory and Scientific Services Directorate are research partners for this project. Using generic hydrocarbon, industrially available, metal oxide sensors as illicit material detectors, requires usage precautions. Indeed, neither the product's concentrations, nor even the products themselves, belong to the intended usage specifications. Therefore, the CREL is currently investigating two major research topics: controlling the sensor's environment: with environmental control we improve the detection of small product concentration; determining detection thresholds: both drugs and explosives disseminate low gas concentration. We are attempting to quantify the minimal concentration which triggers detection. In the long run, we foresee a computer-based tool likely to detect a target gas in a noisy atmosphere. A neural network is the suitable tool for interpreting the response of heterogeneous sensor matrix. This information processing structure, alongside with proper sensor environment control, will lessen the repercussions of common MOS sensor sensitivity characteristic dispersion.

  10. New Fast Shower Max Detector Based on MCP as an Active Element

    NASA Astrophysics Data System (ADS)

    Ronzhin, A.; Los, S.; Ramberg, E.; Spiropulu, M.; Apresyan, A.; Xie, S.; Kim, H.; Zatserklyaniy, A.

    2015-02-01

    One possibility to make a fast and radiation resistant shower maximum (SM) detector is to use a secondary emitter as an active element. We present below test beam results, obtained with different types of photo detectors based on micro channel plates (MCP) as secondary emitter. The SM time resolution - we obtained for this new type of detector is at the level of 20-30 ps. We estimate that a significant contribution to the detector response originates from secondary emission of the MCP.

  11. Gamma detectors based on high-pressure xenon: their development and application

    NASA Astrophysics Data System (ADS)

    Ulin, Sergey E.; Dmitrenko, Valery V.; Grachev, V. M.; Uteshev, Z. M.; Vlasik, K. F.; Chernysheva, I. V.; Dukhvalov, A. G.; Kotler, F. G.; Pushkin, K. N.

    2004-10-01

    Various modifications of xenon detectors and their parameters in comparison with gamma-detectors of other types are considered. Prospects of xenon detectors' applicatins in gamma-spectroscopy based on experimental results are discussed including detection and control of radioactive and fissile materials displacement, definition of uranium enrichment rate, and measurements of nuclear reactor radioactive gas waste concentration. Possibilities for xenon detector use for environmental control and measurement of cosmic gamma radiation on orbital stations are considered.

  12. Gamma detectors based on high pressure xenon: their development and application

    NASA Astrophysics Data System (ADS)

    Ulin, Sergey E.; Dmitrenko, Valery V.; Grachev, V. M.; Uteshev, Z. M.; Vlasic, K. F.; Chernysheva, I. V.; Duhvalov, A. G.; Kotler, F. G.; Pushkin, K. N.

    2004-01-01

    Various modifications of xenon detectors and their parameters in comparison with gamma-detectors of other types are considered. Prospects of xenon detectors' applications in gamma-spectroscopy based on experimental results are discussed including detection and control of radioactive and fissile materials displacement, definition of uranium enrichment rate, and measurements of nuclear reactor radioactive gas waste concentration. Possibilities for xenon detector use for environmental control and measurement of cosmic gamma radiation on orbital stations are considered.

  13. Position sensitive and energy dispersive x-ray detector based on silicon strip detector technology

    NASA Astrophysics Data System (ADS)

    Wiącek, P.; Dąbrowski, W.; Fink, J.; Fiutowski, T.; Krane, H.-G.; Loyer, F.; Schwamberger, A.; Świentek, K.; Venanzi, C.

    2015-04-01

    A new position sensitive detector with a global energy resolution for the entire detector of about 380 eV FWHM for 8.04 keV line at ambient temperature is presented. The measured global energy resolution is defined by the energy spectra summed over all strips of the detector, and thus it includes electronic noise of the front-end electronics, charge sharing effects, matching of parameters across the channels and other system noise sources. The target energy resolution has been achieved by segmentation of the strips to reduce their capacitance and by careful optimization of the front-end electronics. The key design aspects and parameters of the detector are discussed briefly in the paper. Excellent noise and matching performance of the readout ASIC and negligible system noise allow us to operate the detector with a discrimination threshold as low as 1 keV and to measure fluorescence radiation lines of light elements, down to Al Kα of 1.49 keV, simultaneously with measurements of the diffraction patterns. The measurement results that demonstrate the spectrometric and count rate performance of the developed detector are presented and discussed in the paper.

  14. Polarimetric target detection under uneven illumination.

    PubMed

    Huang, Bingjing; Liu, Tiegen; Han, Jiahui; Hu, Haofeng

    2015-09-01

    In polarimetric imaging, the uneven illumination could cause the significant spatial intensity fluctuations in the scene, and thus hampers the target detection. In this paper, we propose a method of illumination compensation and contrast optimization for Stokes polarimetric imaging, which allows significantly increasing the performance of target detection under uneven illumination. We show with numerical simulation and real-world experiment that, based on the intensity information contained in the polarization information, the contrast can be effectively enhanced by proper approach, which is of particular importance in practical applications with spatial illumination fluctuations, such as remote sensing. PMID:26368458

  15. LAMBDA — Large Area Medipix3-Based Detector Array

    NASA Astrophysics Data System (ADS)

    Pennicard, D.; Lange, S.; Smoljanin, S.; Hirsemann, H.; Graafsma, H.

    2012-11-01

    Medipix3 is a photon-counting readout chip for X-ray detection. It has a small pixel size (55 μm) and a high frame rate with zero dead time, which makes it attractive for experiments at synchrotrons. Using Medipix3, DESY are developing the LAMBDA (Large Area Medipix3-Based Detector Array) system. A single LAMBDA module carries either a single large silicon sensor of 1536 by 512 pixels, or two smaller high-Z sensors. The sensor is bonded to 12 Medipix3 chips, and mounted on a ceramic carrier board. The readout system for the module then provides a fast FPGA, a large RAM and four 10 Gigabit Ethernet links to allow operation at high frame rates. Multiple modules may then be tiled together a larger area. Currently, the first large silicon modules have been constructed and tested at low speed, and the firmware for fast readout is being developed.

  16. Optimizing timing performance of silicon photomultiplier-based scintillation detectors.

    PubMed

    Yeom, Jung Yeol; Vinke, Ruud; Levin, Craig S

    2013-02-21

    Precise timing resolution is crucial for applications requiring photon time-of-flight (ToF) information such as ToF positron emission tomography (PET). Silicon photomultipliers (SiPM) for PET, with their high output capacitance, are known to require custom preamplifiers to optimize timing performance. In this paper, we describe simple alternative front-end electronics based on a commercial low-noise RF preamplifier and methods that have been implemented to achieve excellent timing resolution. Two radiation detectors with L(Y)SO scintillators coupled to Hamamatsu SiPMs (MPPC S10362-33-050C) and front-end electronics based on an RF amplifier (MAR-3SM+), typically used for wireless applications that require minimal additional circuitry, have been fabricated. These detectors were used to detect annihilation photons from a Ge-68 source and the output signals were subsequently digitized by a high speed oscilloscope for offline processing. A coincident resolving time (CRT) of 147 ± 3 ps FWHM and 186 ± 3 ps FWHM with 3 × 3 × 5 mm(3) and with 3 × 3 × 20 mm(3) LYSO crystal elements were measured, respectively. With smaller 2 × 2 × 3 mm(3) LSO crystals, a CRT of 125 ± 2 ps FWHM was achieved with slight improvement to 121 ± 3 ps at a lower temperature (15° C). Finally, with the 20 mm length crystals, a degradation of timing resolution was observed for annihilation photon interactions that occur close to the photosensor compared to shallow depth-of-interaction (DOI). We conclude that commercial RF amplifiers optimized for noise, besides their ease of use, can produce excellent timing resolution comparable to best reported values acquired with custom readout electronics. On the other hand, as timing performance degrades with increasing photon DOI, a head-on detector configuration will produce better CRT than a side-irradiated setup for longer crystals. PMID:23369872

  17. VME-based data acquisition system for the India-based Neutrino Observatory prototype detector

    NASA Astrophysics Data System (ADS)

    Bhuyan, M.; Chandratre, V. B.; Dasgupta, S.; Datar, V. M.; Kalmani, S. D.; Lahamge, S. M.; Mondal, N. K.; Nagaraj, P.; Pal, S.; Rao, S. K.; Redij, A.; Samuel, D.; Saraf, M. N.; Satyanarayana, B.; Shinde, R. R.; Upadhya, S. S.

    2012-01-01

    The India-based Neutrino Observatory (INO) collaboration has proposed to build a 50 kton Iron-Calorimeter (ICAL) to study neutrino oscillations. About 28,800 Resistive Plate Chambers will be used as active detector elements in this experiment. Preliminary studies are currently underway and as a part of it, a prototype detector was developed which now serves as a cosmic-ray telescope and as a test-bench to study the indigenously built RPCs. A VME-based data acquisition system was designed for this prototype system. Modern software tools were used in the designing of the DAQ software. The design and development of this DAQ system are discussed.

  18. Ultrafast soft x-ray two-dimensional plasma imaging system based on gas electron multiplier detector with pixel readout

    NASA Astrophysics Data System (ADS)

    Pacella, D.; Pizzicaroli, G.; Gabellieri, L.; Leigheb, M.; Bellazzini, R.; Brez, A.; Gariano, G.; Latronico, L.; Lumb, N.; Spandre, G.; Massai, M. M.; Reale, S.

    2001-02-01

    In the present article a new diagnostic device in the soft x-ray range, for magnetic fusion plasmas, is proposed based on a gas electron multiplier detector with 2.5×2.5 cm active area, equipped with a true two-dimensional readout system. The readout printed circuit board, designed for these experiments, has 128 pads. Each pad is 2 mm square and covers a roughly circular area. The operational conditions of the detector are settled to work in the x-ray range 3-15 keV at very high counting rates, with a linear response up to 2 MHz/pixel. This limitation is due to the electronic dead time. Images of a wrench and two pinholes were done at rates of 2.5 MHz/pixel with a powerful x-ray laboratory source showing an excellent imaging capability. Finally preliminary measurements of x-ray emission from a magnetic fusion plasma were performed on the Frascati tokamak upgrade experiment. The system was able to image the plasma with a wide dynamic range (more than a factor of 100), with a sampling frequency of 20 kHz and with counting rates up to 4 MHz/pixel, following the changes of the x-ray plasma emissivity due to additional radio frequency heating. The spatial resolution and imaging properties of this detector have been studied in this work for conditions of high counting rates and high gain, with the detector fully illuminated by very intense x-ray sources (laboratory tube and tokamak plasma).

  19. Multiple-illumination photoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Barber, Quinn M.; Zemp, Roger J.

    2016-03-01

    Previously we described the potential for multiple illumination photoacoustic tomography to provide quantitative reconstructions, however this work used only simulated data. We have developed a custom photoacoustic-ultrasound tomography system capable of multiple illuminations and parallel acquisition from a 256 element 5 MHz transducer ring array with 8-cm diameter. The multiple illumination scheme uses a free-space light delivery geometry where a rotational stage scans a pulsed laser beam onto different incident locations around the sample. For each illumination location a photoacoustic image is reconstructed using a modified backprojection algorithm. Images from different source locations have the potential to be combined to form an improved deep-tissue image using our previously developed iterative algorithms. We complement the photoacoustic imaging data with unique ultrasound imaging data. Most previous ultrasound tomography methods have used migration algorithms, iterative ray-based analysis, wave-equation modeling, or frequency-based algorithms that all demand large amounts of data and computational power. We propose a new UST method that offers isotropic resolution, provides scattering contrast, as well as the potential for measuring ultrasound scattering anisotropy and decoupling density and compressibility contributions. The imaging system is driven by a Verasonics scan engine and programmed for both ultrasound and photoacoustic imaging modes. Resolution has been measured to be 150 μm for ultrasound and 200 μm for photoacoustic images. Imaging capabilities are demonstrated on phantoms with custom-tailored ultrasound scattering and optical properties, as well as in murine models.

  20. Fission-fragment detector for DANCE based on thin scintillating films

    NASA Astrophysics Data System (ADS)

    Rusev, G.; Roman, A. R.; Daum, J. K.; Springs, R. K.; Bond, E. M.; Jandel, M.; Baramsai, B.; Bredeweg, T. A.; Couture, A.; Favalli, A.; Ianakiev, K. D.; Iliev, M. L.; Mosby, S.; Ullmann, J. L.; Walker, C. L.

    2015-12-01

    A fission-fragment detector based on thin scintillating films has been built to serve as a trigger/veto detector in neutron-induced fission measurements at DANCE. The fissile material is surrounded by scintillating films providing 4 π detection of the fission fragments. The scintillation photons were registered with silicon photomultipliers. A measurement of the 235U (n , f) reaction with this detector at DANCE revealed a correct time-of-flight spectrum and provided an estimate for the efficiency of the prototype detector of 11.6(7)%. Design and test measurements with the detector are described.

  1. Optical position detectors based on thin film amorphous silicon

    NASA Astrophysics Data System (ADS)

    Henry, Jasmine; Livingstone, John

    2001-10-01

    Thin film optical position sensitive detectors (PSDs) based on novel hydrogenated amorphous silicon Schottky barrier (SB) structures are compared in this work. The three structures reported here have been tested under different light sources to measure their linear properties and wavelength response characteristics. The sputtered a-Si sensors were configured as layered structures of platinum, a-Si and indium tin oxide, forming SB-i-n devices and exhibited linear properties similar to multi-layer a-Si p-i- n devices produced by complex chemical vapor deposition procedures, which involve flammable and toxic gases. All structures were test4ed as possible configurations for 2D sensors. The devices were tested under white light, filtered white light and also a red diode laser. Each of the three structures responded quite differently to each of the sources. Results, based on the correlation coefficient, which measures the linearity of output and which has a maximum value of 1, produced r values ranging between 0.992 to 0.999, in the best performances.

  2. Shackleton Crater Illumination

    NASA Video Gallery

    Simulated illumination conditions near the lunar South Pole. The 30km x 30km region highlights the Shackleton crater. The movie runs for 28 days, centered on the LCROSS impact date on October 9th, ...

  3. Wood's lamp illumination (image)

    MedlinePlus

    A Wood's lamp emits ultraviolet light and can be a diagnostic aid in determining if someone has a fungal ... is an infection on the area where the Wood's lamp is illuminating, the area will fluoresce. Normally ...

  4. Illuminating black holes

    NASA Astrophysics Data System (ADS)

    Barr, Ian A.; Bull, Anne; O’Brien, Eileen; Drillsma-Milgrom, Katy A.; Milgrom, Lionel R.

    2016-07-01

    Two-dimensional shadows formed by illuminating vortices are shown to be visually analogous to the gravitational action of black holes on light and surrounding matter. They could be useful teaching aids demonstrating some of the consequences of general relativity.

  5. Blind multiuser detector for chaos-based CDMA using support vector machine.

    PubMed

    Kao, Johnny Wei-Hsun; Berber, Stevan Mirko; Kecman, Vojislav

    2010-08-01

    The algorithm and the results of a blind multiuser detector using a machine learning technique called support vector machine (SVM) on a chaos-based code division multiple access system is presented in this paper. Simulation results showed that the performance achieved by using SVM is comparable to existing minimum mean square error (MMSE) detector under both additive white Gaussian noise (AWGN) and Rayleigh fading conditions. However, unlike the MMSE detector, the SVM detector does not require the knowledge of spreading codes of other users in the system or the estimate of the channel noise variance. The optimization of this algorithm is considered in this paper and its complexity is compared with the MMSE detector. This detector is much more suitable to work in the forward link than MMSE. In addition, original theoretical bit-error rate expressions for the SVM detector under both AWGN and Rayleigh fading are derived to verify the simulation results. PMID:20570769

  6. Development of stable nuclear radiation detectors based on n-silicon/cobalt-phthalocyanine heterojunctions

    NASA Astrophysics Data System (ADS)

    Ray, A.; Prasad, R.; Betty, C. A.; Chandrasekhar Rao, T. V.

    2016-03-01

    n-silicon/cobalt-phthalocyanine (CoPc) heterojunction based nuclear detectors have been fabricated using thermally evaporated CoPc films. Two different thicknesses of CoPc film (viz. 100 nm and 200 nm) were tried out to make detectors by depositing on chemically polished n-Si wafers. Gold film on CoPc was used as electrical contact. The detectors were characterized by measuring their current-voltage (I-V) and leakage current-time (I-t) characteristics, followed by alpha energy spectra obtained on exposure to α-particles. Variation of alpha energy resolution with applied reverse bias voltage for each of the detectors was also studied. The detectors showed very low leakage current and high breakdown voltage as compared to conventional Au/n-Si surface barrier detectors. Finally, the durability of the detectors was established by measuring their I-V characteristics and energy resolution for nearly 15 months.

  7. Ethernet-Based DAQ System for QUIET-II Detectors

    NASA Astrophysics Data System (ADS)

    Nagai, M.; Ishidoshiro, K.; Higuchi, T.; Ikeno, M.; Hasegawa, M.; Hazumi, M.; Tajima, O.; Tanaka, M.; Uchida, T.

    2012-06-01

    The B-modes in cosmic microwave background polarization are a smoking gun for the inflationary universe. For the detection of the B-modes, having a large detector array is a generic approach since the B-modes is so faint pattern ( T b≲0.1 μK). The Q/U Imaging ExperimenT Phase-II (QUIET-II) is proposed to search the B-modes, using an array with 500 HEMT-based polarimeters. Each polarimeter element has 4-outputs, therefore we have to manage 2000 channels in total. We developed a scalable DAQ system based on TCP/Ethernet for QUIET-II. The DAQ system is composed of the polarimeters, ADC boards, a Master Clock and a control computer (PC). The analog signals from the polarimeters are digitized on the ADC boards. On-board demodulation, which synchronizes the phase flip modulations on the polarimeter, extracts the polarized components in the digitized signal. The Master Clock distributes all necessary clocks to the ADC boards as well as the polarimeters. This scheme guarantees the synchronization of the modulations and demodulations. We employed Ethernet-based communication scheme between the data collection program (Collector) on the PC and the ADC boards as well as the Master Clock. Such an Ethernet-based communication scheme allows us to construct a simple structure of the upper level software, which results in the high scalability to increase the number of channels. All basic functions and requirements are confirmed by the laboratory tests; demonstration with test signals as well as the signals from the polarimeters, measurements of the data transfer rate, and the synchronous operation with two ADC boards. Therefore, the DAQ system is confirmed to be suitable for QUIET-II.

  8. Characterization of the KID-Based Light Detectors of CALDER

    NASA Astrophysics Data System (ADS)

    Casali, N.; Bellini, F.; Cardani, L.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2016-07-01

    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5 × 5 cm2 and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of 0{-}30 keV.

  9. Characterization of the KID-Based Light Detectors of CALDER

    NASA Astrophysics Data System (ADS)

    Casali, N.; Bellini, F.; Cardani, L.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; D'Addabbo, A.; Di Domizio, S.; Martinez, M.; Tomei, C.; Vignati, M.

    2015-11-01

    The aim of the Cryogenic wide-Area Light Detectors with Excellent Resolution (CALDER) project is the development of light detectors with active area of 5 × 5 cm2 and noise energy resolution smaller than 20 eV RMS, implementing phonon-mediated kinetic inductance detectors. The detectors are developed to improve the background suppression in large-mass bolometric experiments such as CUORE, via the double read-out of the light and the heat released by particles interacting in the bolometers. In this work, we present the characterization of the first light detectors developed by CALDER. We describe the analysis tools to evaluate the resonator parameters (resonant frequency and quality factors) taking into account simultaneously all the resonance distortions introduced by the read-out chain (as the feed-line impedance and its mismatch) and by the power stored in the resonator itself. We detail the method for the selection of the optimal point for the detector operation (maximizing the signal-to-noise ratio). Finally, we present the response of the detector to optical pulses in the energy range of 0{-}30 keV.

  10. Study of a nTHGEM-based thermal neutron detector

    NASA Astrophysics Data System (ADS)

    Li, Ke; Zhou, Jian-Rong; Wang, Xiao-Dong; Xiong, Tao; Zhang, Ying; Xie, Yu-Guang; Zhou, Liang; Xu, Hong; Yang, Gui-An; Wang, Yan-Feng; Wang, Yan; Wu, Jin-Jie; Sun, Zhi-Jia; Hu, Bi-Tao

    2016-07-01

    With new generation neutron sources, traditional neutron detectors cannot satisfy the demands of the applications, especially under high flux. Furthermore, facing the global crisis in 3He gas supply, research on new types of neutron detector as an alternative to 3He is a research hotspot in the field of particle detection. GEM (Gaseous Electron Multiplier) neutron detectors have high counting rate, good spatial and time resolution, and could be one future direction of the development of neutron detectors. In this paper, the physical process of neutron detection is simulated with Geant4 code, studying the relations between thermal conversion efficiency, boron thickness and number of boron layers. Due to the special characteristics of neutron detection, we have developed a novel type of special ceramic nTHGEM (neutron THick GEM) for neutron detection. The performance of the nTHGEM working in different Ar/CO2 mixtures is presented, including measurements of the gain and the count rate plateau using a copper target X-ray source. A detector with a single nTHGEM has been tested for 2-D imaging using a 252Cf neutron source. The key parameters of the performance of the nTHGEM detector have been obtained, providing necessary experimental data as a reference for further research on this detector. Supported by National Natural Science Foundation of China (11127508, 11175199, 11205253, 11405191), Key Laboratory of Neutron Physics, CAEP (2013DB06, 2013BB04) and CAS (YZ201512)

  11. A beta-ray spectrometer based on a two-or three silicon detector coincidence telescope

    NASA Astrophysics Data System (ADS)

    Horowitz, Y. S.; Weizman, Y.; Hirning, C. R.

    1996-02-01

    This report describes the operation of a beta-ray energy spectrometer based on a silicon detector telescope using two or three elements. The front detector is a planar, totally-depleted, silicon surface barrier detector that is 97 μm thick, the back detector is a room-temperature, lithium compensated, silicon detector that is 5000 μm thick, and the intermediate detector is similar to the front detector but 72 μm thick and intended to be used only in intense photon fields. The three detectors are mounted in a light-tight aluminum housing. The capability of the spectrometer to reject photons is based upon the fact that the incident photon will have a small probability of simultaneously losing detectable energy in two detectors, and an even smaller probability of losing detectable energy in all three detectors. Electrons will, however, almost always record measurable events in either the front two or all three detectors. A coincidence requirement between the detectors thus rejects photon induced events. With a 97 μm thick detector the lower energy coincidence threshold is approximately 110 keV. With an ultra-thin 40 μm thick front detector, and operated at 15°C, the spectrometer is capable of detecting even 60-70 keV electrons with a coincidence efficiency of 60%. The spectrometer has been used to measure beta radiation fields in CANDU reactor working environments, and the spectral information is intended to support dose algorithms for the LiF TLD chips used in the Ontario Hydro dosimetry program.

  12. Self-powered flexible and transparent photovoltaic detectors based on CdSe nanobelt/graphene Schottky junctions.

    PubMed

    Gao, Zhiwei; Jin, Weifeng; Zhou, Yu; Dai, Yu; Yu, Bin; Liu, Chu; Xu, Wanjin; Li, Yanping; Peng, Hailin; Liu, Zhongfan; Dai, Lun

    2013-06-21

    Flexible and transparent electronic and optoelectronic devices have attracted more and more research interest due to their potential applications in developing portable, wearable, low-cost, and implantable devices. We have fabricated and studied high-performance flexible and transparent CdSe nanobelt (NB)/graphene Schottky junction self-powered photovoltaic detectors for the first time. Under 633 nm light illumination, typical photosensitivity and responsivity of the devices are about 1.2 × 10(5) and 8.7 A W(-1), respectively. Under 3500 Hz switching frequency, the response and recovery times of them are about 70 and 137 μs, respectively, which, to the best of our knowledge, are the best reported values for nanomaterial based Schottky junction photodetectors up to date. The detailed properties of the photodetectors, such as the influences of incident light wavelength and light intensity on the external quantum efficiency and speed, are also investigated. Detailed discussions are made in order to understand the observed phenomena. Our work demonstrates that the self-powered flexible and transparent CdSe NB/graphene Schottky junction photovoltaic detectors have a bright application prospect. PMID:23681339

  13. A high-dynamic range (HDR) back-side illuminated (BSI) CMOS image sensor for extreme UV detection

    NASA Astrophysics Data System (ADS)

    Wang, Xinyang; Wolfs, Bram; Bogaerts, Jan; Meynants, Guy; BenMoussa, Ali

    2012-03-01

    This paper describes a back-side illuminated 1 Megapixel CMOS image sensor made in 0.18um CMOS process for EUV detection. The sensor applied a so-call "dual-transfer" scheme to achieve low noise, high dynamic range. The EUV sensitivity is achieved with backside illumination use SOI-based solution. The epitaxial silicon layer is thinned down to less than 3um. The sensor is tested and characterized at 5nm to 30nm illumination. At 17.4nm targeted wavelength, the detector external QE (exclude quantum yield factor) reaches almost 60%. The detector reaches read noise of 1.2 ph- (@17.4nm), i.e. close to performance of EUV photon counting.

  14. Physics-based generation of gamma-ray response functions for CDZNTE detectors

    SciTech Connect

    Prettyman, T.H.; Mercer, D.J.; Cooper, C.; Russo, P.A.; Rawool-Sullivan, M.; Close, D.A.; Luke, P.N.; Amman, M.; Soldner, S.

    1997-09-01

    A physics-based approach to gamma-ray response-function generation is presented in which the response of CdZnTe detectors is modeled from first principles. Computer modeling is used to generate response functions needed for spectrum analysis for general detector configurations (e.g., electrode design, detector materials and geometry, and operating conditions). With computer modeling, requirements for calibration and characterization are significantly reduced. Elements of the physics-based model, including gamma-ray transport, charge drift-diffusion, and circuit response, are presented. Calculated and experimental gamma-ray spectra are compared for a coplanar-grid CdZnTe detector.

  15. Electronics and data acquisition system for the ICAL prototype detector of India-based neutrino observatory

    NASA Astrophysics Data System (ADS)

    Behere, A.; Bhuyan, M.; Chandratre, V. B.; Dasgupta, S.; Datar, V. M.; Kalmani, S. D.; Lahamge, S. M.; Mondal, N. K.; Mukhopadhyay, P. K.; Nagaraj, P.; Nagesh, B. K.; Pal, S.; Rao, Shobha K.; Samuel, D.; Saraf, M. N.; Satyanarayana, B.; Shastrakar, R. S.; Shinde, R. R.; Sudheer, K. M.; Upadhya, S. S.; Verma, P.

    2013-02-01

    The India-based Neutrino Observatory (INO) collaboration has proposed to build a 50 kton magnetized Iron Calorimeter (ICAL) detector with the primary goal to study neutrino oscillations, employing Resistive Plate Chambers (RPCs) as active detector elements. A prototype of the ICAL detector has been built in order to develop and characterize the intrinsic sub-systems, like RPCs, gas system, electronics and data acquisition system, etc. This paper describes in detail the readout electronics as well as the VME-based data acquisition system for the prototype detector.

  16. Minimal Conductance-Based Model of Auditory Coincidence Detector Neurons

    PubMed Central

    Ashida, Go; Funabiki, Kazuo; Kretzberg, Jutta

    2015-01-01

    Sound localization is a fundamental sensory function of a wide variety of animals. The interaural time difference (ITD), an important cue for sound localization, is computed in the auditory brainstem. In our previous modeling study, we introduced a two-compartment Hodgkin-Huxley type model to investigate how cellular and synaptic specializations may contribute to precise ITD computation of the barn owl's auditory coincidence detector neuron. Although our model successfully reproduced fundamental physiological properties observed in vivo, it was unsuitable for mathematical analyses and large scale simulations because of a number of nonlinear variables. In the present study, we reduce our former model into three types of conductance-based integrate-and-fire (IF) models. We test their electrophysiological properties using data from published in vivo and in vitro studies. Their robustness to parameter changes and computational efficiencies are also examined. Our numerical results suggest that the single-compartment active IF model is superior to other reduced models in terms of physiological reproducibility and computational performance. This model will allow future theoretical studies that use more rigorous mathematical analysis and network simulations. PMID:25844803

  17. MEMS-based infrared detector for body thermometer

    NASA Astrophysics Data System (ADS)

    Yoo, Kum-Pyo; Kim, Yun-Ho; Min, Nam-Ki

    2005-12-01

    Infrared detectors have many application fields. One of those, MEMS based thermopile is attractive for many low-cost commercial and industrial applications, mainly because it does not require cooling for operation and the process technologies are relatively simple. The MEMS thermopile fabricated on a silicon nitride microbridge structure was proposed. Using microbridge rather conventional membrane makes it possible to fabricate much smaller micro thermopile and to reduce heat loss because of small contact area at silicon rim. The bridge material is only composed of Si3N4. The thermocouple was used a poly-Si and an aluminum. The characteristic of electromotive force (EMF) generation was evaluated for various patterns at hot junction. Aluminum thermocouple shape on bridge structure was designed two patterns. One was a square shape and the other shape was a hollow square. The output voltage of hollow square-type electrode was increased in compared with square-type electrode from 3.03uV/°C to 4.609uV/°C at body temperature (37°C). With the same membrane dimensions and the same overall thickness of the chip a thermopile on microbridge is almost 53% smaller a conventional thermopile chip.

  18. Low power adder based digital filter for QRS detector.

    PubMed

    Murali, L; Chitra, D; Manigandan, T

    2014-01-01

    Most of the Biomedical applications use dedicated processors for the implementation of complex signal processing. Among them, sensor network is also a type, which has the constraint of low power consumption. Since the processing elements are the most copiously used operations in the signal processors, the power consumption of this has the major impact on the system level application. In this paper, we introduce low power concept of transistor stacking to reduce leakage power; and new architectures based on stacking to implement the full adder and its significance at the digital filter level for QRS detector are implemented. The proposed concept has lesser leakage power at the adder as well as filter level with trade-off in other quality metrics of the design. This enabled the design to be dealt with as the low-power corner and can be made adaptable to any level of hierarchical abstractions as per the requirement of the application. The proposed architectures are designed, modeled at RTL level using the Verilog-HDL, and synthesized in Synopsys Design Compiler by mapping the design to 65 nm technology library standard cells. PMID:24895649

  19. Airplane Ice Detector Based on a Microwave Transmission Line

    NASA Technical Reports Server (NTRS)

    Ngo, Phong; Arndt, G. Dickey; Carl, James R.

    2004-01-01

    An electronic instrument that could detect the potentially dangerous buildup of ice on an airplane wing is undergoing development. The instrument is based on a microwave transmission line configured as a capacitance probe: at selected spots, the transmission-line conductors are partly exposed to allow any ice and/or liquid water present at those spots to act as predominantly capacitive electrical loads on the transmission line. These loads change the input impedance of the transmission line, as measured at a suitable excitation frequency. Thus, it should be possible to infer the presence of ice and/or liquid water from measurements of the input impedance and/or electrical parameters related to the input impedance. The sensory transmission line is of the microstrip type and thus thin enough to be placed on an airplane wing without unduly disturbing airflow in flight. The sensory spots are small areas from which the upper layer of the microstrip has been removed to allow any liquid water or ice on the surface to reach the transmission line. The sensory spots are spaced at nominal open-circuit points, which are at intervals of a half wavelength (in the transmission line, not in air) at the excitation frequency. The excitation frequency used in the experiments has been 1 GHz, for which a half wavelength in the transmission line is .4 in. (.10 cm). The figure depicts a laboratory prototype of the instrument. The impedance-related quantities chosen for use in this version of the instrument are the magnitude and phase of the scattering parameter S11 as manifested in the in-phase (I ) and quadrature (Q) outputs of the phase detector. By careful layout of the transmission line (including the half-wavelength sensor spacing), one can ensure that the amplitude and phase of the input to the phase detector keep shifting in the same direction as ice forms on one or more of the sensor areas. Although only one transmission-line sensor strip is used in the laboratory version, in a

  20. Performance of a PSPMT based detector for scintimammography.

    PubMed

    Williams, M B; Williams, M B; Goode, A R; Galbis-Reig, V; Majewski, S; Weisenberger, A G; Wojcik, R

    2000-03-01

    In breast scintigraphy, compact detectors with high intrinsic spatial resolution and small inactive peripheries can provide improvements in extrinsic spatial resolution, efficiency and contrast for small lesions relative to larger conventional cameras. We are developing a pixelated small field-of-view gamma camera for scintimammography. Extensive measurements of the imaging properties of a prototype system have been made, including spatial resolution, sensitivity, uniformity of response, geometric linearity and energy resolution. An anthropomorphic torso phantom providing a realistic breast exit gamma spectrum has been used in a qualitative study of lesion detectability. A new type of breast imaging system that combines scintimammography and digital mammography in a single upright unit has also been developed. The system provides automatic co-registration between the scintigram and the digital mammogram, obtained with the breast in a single configuration. Intrinsic spatial resolution was evaluated via calculation of the phase-dependent modulation transfer function (MTF). Measurements of extrinsic spatial resolution, sensitivity and uniformity of response were made for two types of parallel hole collimator using NEMA (National Electrical Manufacturers Association) protocols. Geometric linearity was quantified using a line input and least squares analysis of the measured line shape. Energy resolution was measured for seven different crystal types, and the effectiveness of optical grease coupling was assessed. Exit gamma spectra were obtained using a cadmium zinc telluride based spectrometer. These were used to identify appropriate radioisotope concentrations for the various regions of an anthropomorphic torso phantom, such that realistic scatter conditions could be obtained during phantom measurements. For prone scintimammography, a special imaging table was constructed that permits simultaneous imaging of both breasts, as well as craniocaudal views. A dedicated

  1. Performance of 6cmx6cm MCP-based picosecond photo-detectors

    NASA Astrophysics Data System (ADS)

    Wang, Jingbo; Xie, Junqi; Wagner, Robert; Walters, Dean; Byrum, Karen; Xia, Lei; Zhao, Allen; May, Edward; Demarteau, Marcel; Anlpd Team

    2015-04-01

    Microchannel plate (MCP)-based photo-detectors are capable of micron-level spatial imaging and picosecond-level timing resolution, making them a promising candidate for the next generation high-precision photo-detectors. Argonne National Laboratory (ANL) is currently producing 6x6 cm2, cost-effective, thin planar, glass-body, MCP-based photo-detectors at a newly constructed production system. An indium sealing technique was successfully developed for a permanent detector seal and a several photo-detectors have been produced. The performance of the photo-detectors were characterized with a pulsed laser facility, showing a 60 ps Transit Time Spread (TTS) resolution and <500 μm spatial resolution. The test setup, data acquisition, data analysis and the experimental results will be presented and discussed.

  2. Simulation for Iron Calorimeter prototype detector of India-based Neutrino Observatory

    SciTech Connect

    Ghosh, Tapasi; Chattopadhyay, Subhasis

    2010-03-30

    The India-based Neutrino Observatory (INO) collaboration is proposing to build a 50 kton magnetized iron calorimeter (ICAL) detector in an underground laboratory to be located in South India. As a first step towards building the ICAL detector, a 35 ton prototype of the same design has been set up on the surface to track cosmic ray muons. This paper discusses the prototype detector geometry simulation by GEANT4, and the detector response to the cosmic muons. We have developed a track fitting procedure based on the Kalman Filter technique for the prototype detector when the detector is exposed to single muon tracks. The relevant track parameters i.e., momentum, direction and charge are reconstructed and analyzed. Finally we show the resolution of reconstructed momenta.

  3. Theoretical performance analysis for CMOS based high resolution detectors.

    PubMed

    Jain, Amit; Bednarek, Daniel R; Rudin, Stephen

    2013-03-01

    High resolution imaging capabilities are essential for accurately guiding successful endovascular interventional procedures. Present x-ray imaging detectors are not always adequate due to their inherent limitations. The newly-developed high-resolution micro-angiographic fluoroscope (MAF-CCD) detector has demonstrated excellent clinical image quality; however, further improvement in performance and physical design may be possible using CMOS sensors. We have thus calculated the theoretical performance of two proposed CMOS detectors which may be used as a successor to the MAF. The proposed detectors have a 300 μm thick HL-type CsI phosphor, a 50 μm-pixel CMOS sensor with and without a variable gain light image intensifier (LII), and are designated MAF-CMOS-LII and MAF-CMOS, respectively. For the performance evaluation, linear cascade modeling was used. The detector imaging chains were divided into individual stages characterized by one of the basic processes (quantum gain, binomial selection, stochastic and deterministic blurring, additive noise). Ranges of readout noise and exposure were used to calculate the detectors' MTF and DQE. The MAF-CMOS showed slightly better MTF than the MAF-CMOS-LII, but the MAF-CMOS-LII showed far better DQE, especially for lower exposures. The proposed detectors can have improved MTF and DQE compared with the present high resolution MAF detector. The performance of the MAF-CMOS is excellent for the angiography exposure range; however it is limited at fluoroscopic levels due to additive instrumentation noise. The MAF-CMOS-LII, having the advantage of the variable LII gain, can overcome the noise limitation and hence may perform exceptionally for the full range of required exposures; however, it is more complex and hence more expensive. PMID:24353390

  4. Characterization of Silicon Photomultiplier based detectors with digital electronics

    NASA Astrophysics Data System (ADS)

    Daugherty, Hadyn; Taylor, Steven; Hasse, Adam; Grzywacz, Robert

    2014-09-01

    Due to their compact design and good timing performance Silicon Photomultipliers (SiPMT) were chosen to be used to readout the light from the plastic scintillator detector used as a trigger for the Versatile Array of Neutron Detectors at Low Energy (VANDLE). Prior to development of the new system, we have performed proof of principle studies, to demonstrate that the SiPMT, provided by Sensl is a viable replacement for the conventional photomultiplier. We have build a prototype detector, develop electronics readout chain and characterized its performance using the Digital Data Acquisition system at the University of Tennessee. This experience led to construction of segmented trigger detector which will be used in future VANDLE experiments. *This research was sponsored in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement No. DE-FG52-08NA28552 and the DOE Office of Nuclear Physics. Due to their compact design and good timing performance Silicon Photomultipliers (SiPMT) were chosen to be used to readout the light from the plastic scintillator detector used as a trigger for the Versatile Array of Neutron Detectors at Low Energy (VANDLE). Prior to development of the new system, we have performed proof of principle studies, to demonstrate that the SiPMT, provided by Sensl is a viable replacement for the conventional photomultiplier. We have build a prototype detector, develop electronics readout chain and characterized its performance using the Digital Data Acquisition system at the University of Tennessee. This experience led to construction of segmented trigger detector which will be used in future VANDLE experiments. *This research was sponsored in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement No. DE-FG52-08NA28552 and the DOE Office of Nuclear Physics. University of Tennessee

  5. Model-based beam control for illumination of remote objects, part I: theory and near real-time feasibility

    NASA Astrophysics Data System (ADS)

    Chandler, Susan M.; Lukesh, Gordon W.; Voelz, David; Basu, Santasri; Sjogren, Jon

    2004-10-01

    On September 1, 2003, Nukove Scientific Consulting, together with partner New Mexico State University (NMSU), began work on a Phase I Small Business Technology TRansfer (STTR) grant from the Air Force Office of Scientific Research (AFOSR). The purpose of the grant was to show the feasibility of taking Nukove's pointing estimation technique from a post-processing tool for estimation of laser system characteristics to a real-time tool usable in the field. Nukove's techniques for pointing, shape, and OCS estimation do not require an imaging sensor nor a target board, thus estimates may be made very quickly. To prove feasibility, Nukove developed an analysis tool RHINO (Real-time Histogram Interpretation of Numerical Observations) and successfully demonstrated the emulation of real-time, frame-by-frame estimation of laser system charcteristics, with data streamed into the tool and the estimates displayed as they are made. The eventual objective will be to use the frame-by-frame estimates to allow for feedback to a fielded system. Closely associated with this, NMSU has developed a laboratory testbed to illuminate test objects, collect the received photons, and stream the data into RHINO. The two coupled efforts clearly demonstrate the feasibility of real-time pointing control of a laser system.

  6. Bright field illumination system

    NASA Technical Reports Server (NTRS)

    Huber, Edward D. (Inventor)

    1998-01-01

    A Bright Field Illumination system for inspecting a range of characteristically different kinds of defects, depressions, and ridges in a selected material surface. The system has an illumination source placed near a first focus of an elliptical reflector. In addition, a camera facing the inspected area is placed near the illumination source and the first focus. The second focus of the elliptical reflector is located at a distance approximately twice the elliptical reflector's distance above the inspected surface. The elliptical reflector directs the light from the source onto the inspected surface. Due to the shape of the elliptical reflector, light that is specularly reflected from the inspected surface is directed into the camera is which located at the position of the reflected second focus of the ellipse. This system creates a brightly lighted background field against which damage sites appear as high contrast dark objects which can be easily detected by a person or an automated inspection system. In addition, the Bright Field Illumination system and method can be used in combination with a vision inspection system providing for multiplexed illumination and data handling of multiple kinds of surface characteristics including abrupt and gradual surface variations and differences between measured characteristics of different kinds and prior instruments.

  7. 25 Gb/s photoreceiver based on vertical-illumination type Ge-on-Si photodetector and CMOS amplifier circuit for optical interconnects

    NASA Astrophysics Data System (ADS)

    Joo, Jiho; Jang, Ki-Seok; Kim, Sanghoon; Kim, In Gyoo; Oh, Jin Hyuk; Kim, Sun Ae; Kim, Gyungock; Jeong, Gyu-Seob; Chi, Hankyu; Jeong, Deog-Kyoon

    2015-02-01

    We report the silicon photonic receivers based on the hybrid-integrated vertical-illumination-type germanium-on-silicon photodetector and CMOS amplifier circuit, for optical interconnects. The high-speed vertical-illumination-type Ge-on-Si photodetector is defined on a bulk-silicon wafer, and the CMOS amplifier chip was designed with 65nm ground rule. The PCB-packaged 4 channel 25 Gb/s photoreceiver exhibits a resposivity of 0.68A/W. The sensitivity measured at a BER of 10-12 is -8.3 dBm and -2.4dBm for 25Gb/s and 32Gb/s, respectively. The energy efficiency is 2.19 pJ/bit at 25 Gb/s. The single-channel butterfly-packaged photoreceiver exhibits the sensitivity of -11dBm for 25 Gb/s at a BER of 10-12. The energy efficiency is 2.67 pJ/bit at 25 Gb/s.

  8. [Calorimeter based detectors for high energy hadron colliders]. [Progress report

    SciTech Connect

    Not Available

    1992-08-04

    This document provides a progress report on research that has been conducted under DOE Grant DEFG0292ER40697 for the past year, and describes proposed work for the second year of this 8 year grant starting November 15, 1992. Personnel supported by the contract include 4 faculty, 1 research faculty, 4 postdocs, and 9 graduate students. The work under this grant has in the past been directed in two complementary directions -- DO at Fermilab, and the second SSC detector GEM. A major effort has been towards the construction and commissioning of the new Fermilab Collider detector DO, including design, construction, testing, the commissioning of the central tracking and the central calorimeters. The first DO run is now underway, with data taking and analysis of the first events. Trigger algorithms, data acquisition, calibration of tracking and calorimetry, data scanning and analysis, and planning for future upgrades of the DO detector with the advent of the FNAL Main Injector are all involved. The other effort supported by this grant has been towards the design of GEM, a large and general-purpose SSC detector with special emphasis on accurate muon measurement over a large solid angle. This effort will culminate this year in the presentation to the SSC laboratory of the GEM Technical Design Report. Contributions are being made to the detector design, coordination, and physics simulation studies with special emphasis on muon final states. Collaboration with the RD5 group at CERN to study muon punch through and to test cathode strip chamber prototypes was begun.

  9. The Next Generation of Ground-based Gravitational Wave Detectors

    NASA Astrophysics Data System (ADS)

    Losurdo, Giovanni; LIGO Scientific Collaboration; Virgo Collaboration

    2007-12-01

    LIGO, Virgo and GEO600, the first generation long-baseline interferometric detectors of gravitational waves, were taking data up until last fall. The analysis of the data collected is in progress and the first detection might be possible with these instruments. But, more sensitive detectors will be needed to start the field of gravitational wave astronomy. Advanced interferometers will improve the sensitivity by a factor of ten, thus enabling the exploration of a universe volume that is 1000 times larger than the present. The technology is almost ready and the construction of Advanced LIGO and Advanced Virgo is planned to start at the beginning of the next decade. With an expected event rate of 1/week-1/day these detectors will be powerful instruments that will provide a new way of observing the universe. As an intermediate step, in 2008 LIGO and Virgo will start the upgrade of the current detectors, working towards Enhanced LIGO and Virgo+. GEO600 has also planned a set of incremental upgrades (GEO HF) in order to enhance sensitivity in the high frequency range. In this talk the path towards the advanced detectors will be reviewed and the perspectives of the so-called 2nd generation long-baseline interferometers will be outlined.

  10. A Selenium-Based Detector System For Digital Slot-Radiography

    NASA Astrophysics Data System (ADS)

    Hillen, W.; Schiebel, U.; Zaengel, T.

    1988-06-01

    A research system for digital radiography is described, which is based on a selenium detector with capacitive probe readout. The detector, in which a selenium drum is used as the primary image receptor, is exposed by a scanning fan beam. Scatter reduction and primary transmission by slot-radiography as well as the imaging properties of the selenium detector are discussed. The spatial resolution and the noise behaviour of the detector are analysed. The signal-to-noise ratios expressed in terms of noise equivalent quanta and detective quantum efficiency are calculated and compared with competitive systems.

  11. Study of aging of nuclear detector based on n-silicon/copper phthalocyanine heterojunction

    SciTech Connect

    Ray, A.; Gupta, S. K.

    2013-02-05

    Nuclear detectors based on n-silicon/copper-phthalocyanine (CuPc) heterojunction were fabricated using thermally evaporated CuPc thin film. These detectors exhibited stable electrical and {alpha}-particle characteristics for prolonged periods of time under ordinary laboratory conditions and also exposing to {alpha}- particles (during {alpha}- spectroscopic measurements). The electrical and alpha particle characteristics of these detectors were studied after a long gap of 3 - 5 years and the best result obtained from one detector (five year old) is reported here. Degradation in electrical and alpha particle characteristics were not found to be very significant over the period.

  12. Development of wide-ranged diamond-based detector unit for gamma radiation measurement

    NASA Astrophysics Data System (ADS)

    Baranova, M. A.; Boyko, A. V.; Chebyshev, S. B.; Cherkashin, I. I.; Kireev, V. P.; Petrov, V. I.

    2016-02-01

    In the article the description of wide-ranged diamond-based detector unit is given. Characteristics of the diamond detector were studied in current and in impulse mode. As well it was studied how detector's sensitivity depends on power doze within the limits from 10-3 to 0,4Gy/h (impulse mode) and from 10-1to 2 104Gy/h (current mode). On the basis of the obtained data it is possible to estimate about the possibility of using the detector to prevent emergency accident on a nuclear power plant and for everyday control at a nuclear power plant.

  13. Flexible infrared detectors based on p-n junctions of multi-walled carbon nanotubes.

    PubMed

    Huang, Zhenlong; Gao, Min; Yan, Zhuocheng; Pan, Taisong; Liao, Feiyi; Lin, Yuan

    2016-05-14

    Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm(-2) even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors. PMID:27101973

  14. An Omnidirectional Polarization Detector Based on a Metamaterial Absorber.

    PubMed

    Zhang, Binzhen; Zhang, Yong; Duan, Junping; Zhang, Wendong; Wang, Wanjun

    2016-01-01

    The theory, design, simulation, fabrication, and performance of an omnidirectional polarization detector (PD) with two resonances located in the X and Ka ranges based on a metamaterial absorber (MMA) are presented in this paper. The sandwich structure of PD is composed of 0.1 μm periodic "I" shaped patches on the metasurface, a dielectric of 200 μm FR-4 on the interlayer, and a 0.3 μm copper film on the substrate. PD absorptivity is first used to reflect and describe the polarization of the incident wave. The numerical results, derived from the standard full wave finite integration technology (FIT) of CST 2015, indicates that the designed PD shows polarization sensitivity at all incidence angles. The effects on absorptivity produced by the incidence angles, polarization angles, and materials are investigated. The amplitude of absorptivity change caused by polarization reaches 99.802%. A laser ablation process is adopted to prepare the designed PD on a FR-4 board coated with copper on the double plane with a thickness that was 1/93 and 1/48 of wavelength at a resonance frequency of 16.055 GHz and 30.9 GHz, respectively. The sample test results verify the designed PD excellent detectability on the polarization of the incident waves. The proposed PD, which greatly enriches the applications of metamaterials in bolometers, thermal images, stealth materials, microstructure measurements, and electromagnetic devices, is easy to mass produce and market because of its strong detectability, ultrathin thickness, effective cost, and convenient process. PMID:27455280

  15. Design and construct of a new detector for gas chromatography based on continuous negative corona discharge.

    PubMed

    Ghahfarokhi, M Sharifian; Khayamian, T

    2011-05-01

    In this work, a new detector was designed and constructed based on negative corona discharge. This detector can be used separately or as a detector in gas chromatography. The detector and chromatographic variables including cell temperature, gas flow rates, voltage between the two electrodes, and column temperature were optimized. Chloroform was used as a test compound to evaluate the performance of the detector. The detection limit of chloroform was obtained 0.78 ng∕ml and its dynamic range was over the range of 2-840 ng∕ml. The relative standard detection was about 6% for the limit of quantification. This detector is able to be used as an alternative for analysis of compounds containing electronegative elements. PMID:21639545

  16. A measurement method of a detector response function for monochromatic electrons based on the Compton scattering

    NASA Astrophysics Data System (ADS)

    Bakhlanov, S. V.; Bazlov, N. V.; Derbin, A. V.; Drachnev, I. S.; Kayunov, A. S.; Muratova, V. N.; Semenov, D. A.; Unzhakov, E. V.

    2016-06-01

    In this paper we present a method of scintillation detector energy calibration using the gamma-rays. The technique is based on the Compton scattering of gamma-rays in a scintillation detector and subsequent photoelectric absorption of the scattered photon in the Ge-detector. The novelty of this method is that the source of gamma rays, the germanium and scintillation detectors are immediately arranged adjacent to each other. The method presents an effective solution for the detectors consisting of a low atomic number materials, when the ratio between Compton effect and photoelectric absorption is large and the mean path of gamma-rays is comparable to the size of the detector. The technique can be used for the precision measurements of the scintillator light yield dependence on the electron energy.

  17. Defective pixel map creation based on wavelet analysis in digital radiography detectors

    NASA Astrophysics Data System (ADS)

    Park, Chun Joo; Lee, Hyoung Koo; Song, William Y.; Achterkirchen, Thorsten Graeve; Kim, Ho Kyung

    2011-04-01

    The application of digital radiography detectors has attracted increasing attention in both medicine and industry. Since the imaging detectors are fabricated by semiconductor manufacturing process over large areas, defective pixels in the detectors are unavoidable. Moreover, the radiation damage due to the routine use of the detectors progressively increases the density of defective pixels. In this study, we present a method of identifying defective pixels in digital radiography detectors based on wavelet analysis. Artifacts generated due to wavelet transformations have been prevented by an additional local threshold method. The proposed method was applied to a sample digital radiography and the result was promising. The proposed method uses a single pair of dark and white images and does not require them to be corrected in gain-and-offset properties. This method will be helpful for the reliable use of digital radiography detectors through the working lifetime.

  18. Background illumination simulator

    SciTech Connect

    Towry, E.R.

    1992-05-12

    This patent describes a testing apparatus for testing and evaluating the performance of laser seeking warheads for missiles, under simulated weather conditions. It comprises support means for supporting a warhead seeker; laser means for generating a laser beam and for directing a laser beam towards the seeker; a diffusion screen interposed between the seeker support means and the laser means for diffusing the laser beam; a collimating lens interposed between the diffusion screen and the seeker support means for collimating the diffused laser beam and for directing the collimated laser beam onto a warhead seeker, supported in the seeker support; background illuminator means for illuminating the seeker support and a seeker disposed therein, supported for movement into and out of an operating position between the diffusion means and the collimating lens for providing background lighting in simulation of weather lighting conditions; and control means for controlling the intensity of the light provided by the illuminator means to simulate various weather conditions.

  19. Quantum structure based infrared detector research and development within Acreo’s centre of excellence IMAGIC

    NASA Astrophysics Data System (ADS)

    Andersson, J. Y.; Höglund, L.; Noharet, B.; Wang, Q.; Ericsson, P.; Wissmar, S.; Asplund, C.; Malm, H.; Martijn, H.; Hammar, M.; Gustafsson, O.; Hellström, S.; Radamson, H.; Holtz, P. O.

    2010-07-01

    Acreo has a long tradition of working with quantum structure based infrared (IR) detectors and arrays. This includes QWIP (quantum well infrared photodetector), QDIP (quantum dot infrared photodetector), and InAs/GaInSb based photon detectors of different structure and composition. It also covers R&D on uncooled microbolometers. The integrated thermistor material of such detectors is advantageously based on quantum structures that are optimised for high temperature coefficient and low noise. Especially the SiGe material system is preferred due to the compatibility with silicon technology. The R&D work on IR detectors is a prominent part of Acreo's centre of excellence "IMAGIC" on imaging detectors and systems for non-visible wavelengths. IMAGIC is a collaboration between Acreo, several industry partners and universities like the Royal Institute of Technology (KTH) and Linköping University.

  20. 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.

  1. InAs/AlAsSb based quantum cascade detector

    SciTech Connect

    Reininger, Peter Zederbauer, Tobias; Schwarz, Benedikt; MacFarland, Donald; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried; Detz, Hermann

    2015-08-24

    In this letter, we introduce the InAs/AlAsSb material system for quantum cascade detectors (QCDs). InAs/AlAsSb can be grown lattice matched to InAs and exhibits a conduction band offset of approximately 2.1 eV, enabling the design of very short wavelength quantum cascade detectors. Another benefit using this material system is the low effective mass of the well material that improves the total absorption of the detector and decreases the intersubband scattering rates, which increases the device resistance and thus enhances the noise behavior. We have designed, grown, and measured a QCD that detects at a wavelength of λ = 4.84 μm and shows a peak specific detectivity of approximately 2.7 × 10{sup 7 }Jones at T = 300 K.

  2. Particle tracking with a Timepix based triple GEM detector

    NASA Astrophysics Data System (ADS)

    George, S. P.; Murtas, F.; Alozy, J.; Curioni, A.; Rosenfeld, A. B.; Silari, M.

    2015-11-01

    This paper details the response of a triple GEM detector with a 55 μmetre pitch pixelated ASIC for readout. The detector is operated as a micro TPC with 9.5 cm3 sensitive volume and characterized with a mixed beam of 120 GeV protons and positive pions. A process for reconstruction of incident particle tracks from individual ionization clusters is described and scans of the gain and drift fields are performed. The angular resolution of the measured tracks is characterized. Also, the readout was operated in a mixed mode where some pixels measure drift time and others charge. This was used to measure the energy deposition in the detector and the charge cloud size as a function of interaction depth. The future uses of the device, including in microdosimetry are discussed.

  3. A robot-based detector manipulator system for a hard x-ray nanoprobe instrument.

    SciTech Connect

    Shu, D., Maser, J., Holt, M. , Winarski, R., Preissner, C.,Lai, B., Vogt, S., Stephenson, G.B.

    2007-11-11

    This paper presents the design of a robot-based detector manipulator for microdiffraction applications with a hard X-ray nanoprobe instrument system being constructed at the Advanced Photon Source (APS) for the Center for Nanoscale Materials (CNM) being constructed at Argonne National Laboratory (ANL). Applications for detectors weighing from 1.5 to 100 kg were discussed in three configurations.

  4. OLED area illumination source

    DOEpatents

    Foust, Donald Franklin; Duggal, Anil Raj; Shiang, Joseph John; Nealon, William Francis; Bortscheller, Jacob Charles

    2008-03-25

    The present invention relates to an area illumination light source comprising a plurality of individual OLED panels. The individual OLED panels are configured in a physically modular fashion. Each OLED panel comprising a plurality of OLED devices. Each OLED panel comprises a first electrode and a second electrode such that the power being supplied to each individual OLED panel may be varied independently. A power supply unit capable of delivering varying levels of voltage simultaneously to the first and second electrodes of each of the individual OLED panels is also provided. The area illumination light source also comprises a mount within which the OLED panels are arrayed.

  5. Nonimaging optical illumination system

    DOEpatents

    Winston, R.; Ries, H.

    1998-10-06

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source a light reflecting surface, and a family of light edge rays defined along a reference line with the reflecting surface defined in terms of the reference lines a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line, and D is a distance from a point on the reference line to the reflection surface along the desired edge ray through the point. 35 figs.

  6. Nonimaging optical illumination system

    DOEpatents

    Winston, R.; Ries, H.

    1996-12-17

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source, a light reflecting surface, and a family of light edge rays defined along a reference line with the reflecting surface defined in terms of the reference line as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line, and D is a distance from a point on the reference line to the reflection surface along the desired edge ray through the point. 35 figs.

  7. Dead-time effects in microchannel-plate imaging detectors

    NASA Technical Reports Server (NTRS)

    Zombeck, Martin V.; Fraser, George W.

    1991-01-01

    The observed counting rates of microchannel plate (MCP) based detectors for high resolution observations of celestial EUV and X-ray sources vary over many orders of magnitude; the counting capability of an individual channel, however, is not high, and is associated with dead-times ranging from 0.1 msec to 1 sec. The dead-time increases with the area illuminated; attention is presently given to laboratory determinations of the count rate characteristics of a MCP detector as a function of illuminated area, and a model is developed for these results' use in the interpretation of space observations.

  8. Resonant metamaterial detectors based on THz quantum-cascade structures

    PubMed Central

    Benz, A.; Krall, M.; Schwarz, S.; Dietze, D.; Detz, H.; Andrews, A. M.; Schrenk, W.; Strasser, G.; Unterrainer, K.

    2014-01-01

    We present the design, fabrication and characterisation of an intersubband detector employing a resonant metamaterial coupling structure. The semiconductor heterostructure relies on a conventional THz quantum-cascade laser design and is operated at zero bias for the detector operation. The same active region can be used to generate or detect light depending on the bias conditions and the vertical confinement. The metamaterial is processed directly into the top metal contact and is used to couple normal incidence radiation resonantly to the intersubband transitions. The device is capable of detecting light below and above the reststrahlenband of gallium-arsenide corresponding to the mid-infrared and THz spectral region. PMID:24608677

  9. Predicting Ground Illuminance

    NASA Astrophysics Data System (ADS)

    Lesniak, Michael V.; Tregoning, Brett D.; Hitchens, Alexandra E.

    2015-01-01

    Our Sun outputs 3.85 x 1026 W of radiation, of which roughly 37% is in the visible band. It is directly responsible for nearly all natural illuminance experienced on Earth's surface, either in the form of direct/refracted sunlight or in reflected light bouncing off the surfaces and/or atmospheres of our Moon and the visible planets. Ground illuminance, defined as the amount of visible light intercepting a unit area of surface (from all incident angles), varies over 7 orders of magnitude from day to night. It is highly dependent on well-modeled factors such as the relative positions of the Sun, Earth, and Moon. It is also dependent on less predictable factors such as local atmospheric conditions and weather.Several models have been proposed to predict ground illuminance, including Brown (1952) and Shapiro (1982, 1987). The Brown model is a set of empirical data collected from observation points around the world that has been reduced to a smooth fit of illuminance against a single variable, solar altitude. It provides limited applicability to the Moon and for cloudy conditions via multiplicative reduction factors. The Shapiro model is a theoretical model that treats the atmosphere as a three layer system of light reflectance and transmittance. It has different sets of reflectance and transmittance coefficients for various cloud types.In this paper we compare the models' predictions to ground illuminance data from an observing run at the White Sands missile range (data was obtained from the United Kingdom's Meteorology Office). Continuous illuminance readings were recorded under various cloud conditions, during both daytime and nighttime hours. We find that under clear skies, the Shapiro model tends to better fit the observations during daytime hours with typical discrepancies under 10%. Under cloudy skies, both models tend to poorly predict ground illuminance. However, the Shapiro model, with typical average daytime discrepancies of 25% or less in many cases

  10. Organic Position-Sensitive Detectors Based on ZnO:Al and CuPc:C60.

    PubMed

    Morimune, Taichiro; Kajii, Hirotake; Nishimaru, Hiroki; Ono, Shinji

    2016-04-01

    Organic position-sensitive detector (OPSD) based on copper phthalocyanine CuPc:fullerene C60 bulk-heterojunction with an inverted structure have been fabricated using aluminum doped ZnO (ZnO:Al) as a resistive layer, which is prepared by sol-gel method. The resistance length of the one-dimensional PSD is fixed at 5 mm, and the Ag common electrode is fabricated by vacuum evaporation within the 100-µm width. The current density-voltage characteristics with different structures of photodetector, the influence of ZnO:Al resistivity on the thickness and the position characteristics of PSDs are investigated. The experimental results indicate that the architecture, which uses an inverted structure, increases sensitivity under red light illumination compared to the conventional structure. In addition, the thickness of the ZnO:Al has influence on the position characteristics. The resistivity of ZnO:A film with Al doping concentration of 2 mol% prepared in this study is around 150 Ωcm and it increases from less than approximately 400 nm-thickness. These characteristics seem to be correlated with the properties of ZnO:AI resistive layer. For a device with a 620 nm-thick ZnO:Al layer, the measured position values obtained from the output photocurrent agree with the actual position values under red laser light illumination. CuPc:C60 OPSD with an inverted structure exhibits red light sensitivity, high incident-photon-to-current conversion efficiency of above 80% at -3 V and linearity error of 5.9% at -2 V. PMID:27451643

  11. Flexible infrared detectors based on p-n junctions of multi-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Huang, Zhenlong; Gao, Min; Yan, Zhuocheng; Pan, Taisong; Liao, Feiyi; Lin, Yuan

    2016-05-01

    Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm-2 even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors.Different types of multi-walled carbon nanotubes (CNTs), synthesized by chemical vapor deposition, are used to fabricate infrared (IR) detectors on flexible substrates based on CNT p-n junctions. It is found that this kind of detector is sensitive to infrared signals with a power density as low as 90 μW mm-2 even at room temperature. Besides, unlike other devices, the detector with this unique structure can be bent for 100 cycles without any damage and its functionality does not degenerate once it recovers to the initial state. The results give a good reference for developing efficient, low-cost, and flexible IR detectors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08791k

  12. Performances of a HGCDTE APD Based Detector with Electric Cooling for 2-μm DIAL/IPDA Applications

    NASA Astrophysics Data System (ADS)

    Dumas, A.; Rothman, J.; Gibert, F.; Lasfargues, G.; Zanatta, J.-P.; Edouart, D.

    2016-06-01

    In this work we report on design and testing of an HgCdTe Avalanche Photodiode (APD) detector assembly for lidar applications in the Short Wavelength Infrared Region (SWIR : 1,5 - 2 μm). This detector consists in a set of diodes set in parallel -making a 200 μm large sensitive area- and connected to a custom high gain TransImpedance Amplifier (TIA). A commercial four stages Peltier cooler is used to reach an operating temperature of 185K. Crucial performances for lidar use are investigated : linearity, dynamic range, spatial homogeneity, noise and resistance to intense illumination.

  13. Porous Silicon-Based Quantum Dot Broad Spectrum Radiation Detector

    PubMed Central

    Urdaneta, M.; Stepanov, P.; Weinberg, I. N.; Pala, I. R.; Brock, S.

    2013-01-01

    Silicon is a convenient and inexpensive platform for radiation detection, but has low stopping power for x-rays and gamma-rays with high energy (e.g., 100 keV, as used in computed tomography and digital radiography, or 1 MeV, as desired for detection of nuclear materials). We have effectively increased the stopping power of silicon detectors by producing a layer of porous or micro-machined silicon, and infusing this layer with semiconductor quantum dots made of electron-dense materials. Results of prototype detectors show sensitivity to infrared, visible light, and x-rays, with dark current of less than 1 nA/mm2. PMID:24432047

  14. Performance characteristics of a silicon photomultiplier based compact radiation detector for Homeland Security applications

    NASA Astrophysics Data System (ADS)

    Park, Hye Min; Joo, Koan Sik

    2015-05-01

    A next-generation compact radiation detector was studied for more accurate measurement of radiation and for improvement of detector reliability for the purpose of developing radiation protection technology and military applications. The previously used radiation detector had some limitations due to its bulky size, limited range and its environment for radiation measurement. On the other hand, the compact radiation detector examined in this study utilizes a silicon photomultiplier which appears to be more suitable for this application because of its physical superiority characterized by its small size, high sensitivity, and durability. Accordingly, a SiPM based scintillation detector has been developed as part of this basic study of military radiation detectors. The detector has been tested for its ability to obtain the operating characteristics of a sensor and analyzed with variations of parameter values and for efficiency of detection in accordance with its ability to measure radiation in the environment. Two SiPM based Scintillation detectors with LYSO, BGO and CsI:Tl scintillators were developed and the detectors were analyzed by a number of operating characteristics such as reverse bias, operating temperature and high magnetic field, that depend on environmental changes in radiation measurement. The Photon count rate and spectra were compared for these three scintillators. We found that there were variations in the radiation detection which were characterized by reverse bias, temperature and high magnetic field. It was also found that there was an 11.9% energy resolution for the LYSO, 15.5% for BGO and 13.5% for CsI:Tl using Array SiPM, and 18% for CsI:Tl energy resolution using single SiPM when we measured energy resolution of 511 keV for 22Na. These results demonstrate the potential widespread use of SiPM based compact radiation detectors for Homeland Security applications.

  15. HgZnTe-based detectors for LWIR NASA applications

    NASA Technical Reports Server (NTRS)

    Patten, Elizabeth A.; Kalisher, Murray H.

    1990-01-01

    The initial goal was to grow and characterize HgZnTe and determine if it indeed had the advantageous properties that were predicted. Researchers grew both bulk and liquid phase epitaxial HgZnTe. It was determined that HgZnTe had the following properties: (1) microhardness at least 50 percent greater than HgCdTe of equivalent bandgap; (2) Hg annealing rates of at least 2 to 4 times longer than HgCdTe; and (3) higher Hg vacancy formation energies. This early work did not focus on one specific composition (x-value) of HgZnTe since NASA was interested in HgZnTe's potential for a variety of applications. Since the beginning of 1989, researchers have been concentrating, however, on the liquid phase growth of very long wavelength infrared (VLWIR) HgZnTe (cutoff approx. equals 17 microns at 65K) to address the requirements of the Earth Observing System (EOS). Since there are no device models to predict the advantages in reliability one can gain with increased microhardness, surface stability, etc., one must fabricate HgZnTe detectors and assess their relative bake stability (accelerated life test behavior) compared with HgCdTe devices fabricated in the same manner. Researchers chose to fabricate HIT detectors as a development vehicle for this program because high performance in the VLWIR has been demonstrated with HgCdTe HIT detectors and the HgCdTe HIT process should be applicable to HgZnTe. HIT detectors have a significant advantage for satellite applications since these devices dissipate much less power than conventional photoconductors to achieve the same responsivity.

  16. Development of a Microcantilever-Based Pathogen Detector

    SciTech Connect

    Weeks, B L; Camarero, J; Noy, A; Miller, A E; De Yoreo, J J

    2002-11-18

    The ability to detect small amounts of materials, especially whole organisms, is important for medical diagnostics and national security issues. Engineered micro-mechanical systems can serve as multifunctional, highly sensitive, real time, immunospecific biological detectors under certain circumstances. We present qualitative detection of specific Salmonella strains using a functionalized silicon nitride microcantilever. Detection is achieved due to differential surface stress on the cantilever surface in-situ. Scanning electron micrographs indicate that less than 25 adsorbed bacteria are required for detection.

  17. Novel semiconductor radiation detector based on mercurous halides

    NASA Astrophysics Data System (ADS)

    Chen, Henry; Kim, Joo-Soo; Amarasinghe, Proyanthi; Palosz, Withold; Jin, Feng; Trivedi, Sudhir; Burger, Arnold; Marsh, Jarrod C.; Litz, Marc S.; Wiejewarnasuriya, Priyalal S.; Gupta, Neelam; Jensen, Janet; Jensen, James

    2015-08-01

    The three most important desirable features in the search for room temperature semiconductor detector (RTSD) candidate as an alternative material to current commercially off-the-shelf (COTS) material for gamma and/or thermal neutron detection are: low cost, high performance and long term stability. This is especially important for pager form application in homeland security. Despite years of research, no RTSD candidate so far can satisfy the above 3 features simultaneously. In this work, we show that mercurous halide materials Hg2X2 (X= I, Cl, Br) is a new class of innovative compound semiconductors that is capable of delivering breakthrough advances to COTS radiation detector materials. These materials are much easier to grow thicker and larger volume crystals. They can detect gamma and potentially neutron radiation making it possible to detect two types of radiation with just one crystal material. The materials have wider bandgaps (compared to COTS) meaning higher resistivity and lower leakage current, making this new technology more compatible with available microelectronics. The materials also have higher atomic number and density leading to higher stopping power and better detector sensitivity/efficiency. They are not hazardous so there are no environmental and health concerns during manufacturing and are more stable making them more practical for commercial deployment. Focus will be on Hg2I2. Material characterization and detector performance will be presented and discussed. Initial results show that an energy resolution better than 2% @ 59.6 keV gamma from Am-241 and near 1% @ 662 keV from Cs-137 source can be achieved at room temperature.

  18. Development of LAMBDA: Large Area Medipix-Based Detector Array

    NASA Astrophysics Data System (ADS)

    Pennicard, David; Lange, Sabine; Smoljanin, Sergej; Becker, Julian; Hirsemann, Helmut; Epple, Michael; Graafsma, Heinz

    2011-11-01

    The Medipix3 photon counting readout chip has a range of features — small pixel size, high readout rate and inter-pixel communication — which make it attractive for X-ray scattering and imaging at synchrotrons. DESY have produced a prototype large-area detector module that can carry a 6 by 2 array of Medipix3 chips (1536 by 512 pixels), which can be used with a single large silicon sensor (85mm by 28mm) or two ``hexa'' high-Z sensors. The detector head is designed to be tilable and compatible with low temperatures, and will allow high speed parallel readout of the Medipix3 chips. It consists of a ceramic board, on which the sensor assembly is mounted, and a secondary board for signal routing and voltage regulators. A prototype DAQ board using USB2 readout has also been produced. A ``quad'' Medipix3 sensor assembly has been mounted on the detector head, and successfully configured and read out by the DAQ board. Development has begun on a high-speed readout board, and large-area silicon assemblies are in production.

  19. Miniature Trace Gas Detector Based on Microfabricated Optical Resonators

    NASA Technical Reports Server (NTRS)

    Aveline, David C.; Yu, Nan; Thompson, Robert J.; Strekalov, Dmitry V.

    2013-01-01

    While a variety of techniques exist to monitor trace gases, methods relying on absorption of laser light are the most commonly used in terrestrial applications. Cavity-enhanced absorption techniques typically use high-reflectivity mirrors to form a resonant cavity, inside of which a sample gas can be analyzed. The effective absorption length is augmented by the cavity's high quality factor, or Q, because the light reflects many times between the mirrors. The sensitivity of such mirror-based sensors scales with size, generally making them somewhat bulky in volume. Also, specialized coatings for the high-reflectivity mirrors have limited bandwidth (typically just a few nanometers), and the delicate mirror surfaces can easily be degraded by dust or chemical films. As a highly sensitive and compact alternative, JPL is developing a novel trace gas sensor based on a monolithic optical resonator structure that has been modified such that a gas sample can be directly injected into the cavity. This device concept combines ultra-high Q optical whispering gallery mode resonators (WGMR) with microfabrication technology used in the semiconductor industry. For direct access to the optical mode inside a resonator, material can be precisely milled from its perimeter, creating an open gap within the WGMR. Within this open notch, the full optical mode of the resonator can be accessed. While this modification may limit the obtainable Q, calculations show that the reduction is not significant enough to outweigh its utility for trace gas detection. The notch can be milled from the high- Q crystalline WGMR with a focused ion beam (FIB) instrument with resolution much finer than an optical wavelength, thereby minimizing scattering losses and preserving the optical quality. Initial experimental demonstrations have shown that these opened cavities still support high-Q whispering gallery modes. This technology could provide ultrasensitive detection of a variety of molecular species in an

  20. A new 3He-free thermal neutrons detector concept based on the GEM technology

    NASA Astrophysics Data System (ADS)

    Pietropaolo, A.; Murtas, F.; Claps, G.; Quintieri, L.; Raspino, D.; Celentano, G.; Vannozzi, A.; Frasciello, O.

    2013-11-01

    A thermal neutron detector based on the Gas Electron Multiplier technology is presented. It is configured to let a neutron beam interact with a series of borated glass layers placed in sequence along the neutron path inside the device. The detector has been tested on beam both at the ISIS (UK) spallation neutron source and at the TRIGA reactor of ENEA, at the Casaccia Research Center, near Rome in Italy. For a complete characterization and description of the physical mechanism underlying the detector operation, several Monte Carlo simulations were performed using both Fluka and Geant4 code. These simulations are intended to help in seeking the optimal geometrical set-up and material thickness (converter layer, gas gap, sheet substrate) to improve the final detector design in terms of achieving the best detector efficiency possible.

  1. Terahertz detectors arrays based on orderly aligned InN nanowires

    PubMed Central

    Chen, Xuechen; Liu, Huiqiang; Li, Qiuguo; Chen, Hao; Peng, Rufang; Chu, Sheng; Cheng, Binbin

    2015-01-01

    Nanostructured terahertz detectors employing a single semiconducting nanowire or graphene sheet have recently generated considerable interest as an alternative to existing THz technologies, for their merit on the ease of fabrication and above-room-temperature operation. However, the lack of alignment in nanostructure device hindered their potential toward practical applications. The present work reports ordered terahertz detectors arrays based on neatly aligned InN nanowires. The InN nanostructures (nanowires and nano-necklaces) were achieved by chemical vapor deposition growth, and then InN nanowires were successfully transferred and aligned into micrometer-sized groups by a “transfer-printing” method. Field effect transistors on aligned nanowires were fabricated and tested for terahertz detection purpose. The detector showed good photoresponse as well as low noise level. Besides, dense arrays of such detectors were also fabricated, which rendered a peak responsivity of 1.1 V/W from 7 detectors connected in series. PMID:26289498

  2. Antenna-integrated 0.6 THz FET direct detectors based on CVD graphene.

    PubMed

    Zak, Audrey; Andersson, Michael A; Bauer, Maris; Matukas, Jonas; Lisauskas, Alvydas; Roskos, Hartmut G; Stake, Jan

    2014-10-01

    We present terahertz (THz) detectors based on top-gated graphene field effect transistors (GFETs) with integrated split bow-tie antennas. The GFETs were fabricated using graphene grown by chemical vapor deposition (CVD). The THz detectors are capable of room-temperature rectification of a 0.6 THz signal and achieve a maximum optical responsivity better than 14 V/W and minimum optical noise-equivalent power (NEP) of 515 pW/Hz(0.5). Our results are a significant improvement over previous work on graphene direct detectors and are comparable to other established direct detector technologies. This is the first time room-temperature direct detection has been demonstrated using CVD graphene, which introduces the potential for scalable, wafer-level production of graphene detectors. PMID:25203787

  3. Instruments, Detectors and the Future of Astronomy with Large Ground Based Telescopes

    NASA Astrophysics Data System (ADS)

    Simons, Douglas A.; Amico, Paola; Baade, Dietrich; Barden, Sam; Campbell, Randall; Finger, Gert; Gilmore, Kirk; Gredel, Roland; Hickson, Paul; Howell, Steve; Hubin, Norbert; Kaufer, Andreas; Kohley, Ralf; MacQueen, Philip; Markelov, Sergej; Merrill, Mike; Miyazaki, Satoshi; Nakaya, Hidehiko; O'Donoghue, Darragh; Oliva, Tino; Richichi, Andrea; Salmon, Derrick; Schmidt, Ricardo; Su, Hongjun; Tulloch, Simon; García Vargas, Maria Luisa; Wagner, R. Mark; Wiecha, Olivier; Ye, Binxun

    2005-01-01

    Results of a survey of instrumentation and detector systems, either currently deployed or planned for use at telescopes larger than 3.5 m, in ground based observatories world-wide, are presented. This survey revealed a number of instrumentation design trends at optical, near, and mid-infrared wavelengths. Some of the most prominent trends include the development of vastly larger optical detector systems (> 109 pixels) than anything built to date, and the frequent use of mosaics of near-infrared detectors - something that was quite rare only a decade ago in astronomy. Some future science applications for detectors are then explored, in an attempt to build a bridge between current detectors and what will be needed to support the research ambitions of astronomers in the future.

  4. Nonimaging optical illumination system

    DOEpatents

    Winston, Roland; Ries, Harald

    2000-01-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source 102, a light reflecting surface 108, and a family of light edge rays defined along a reference line 104 with the reflecting surface 108 defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  5. Nonimaging optical illumination system

    DOEpatents

    Winston, Roland; Ries, Harald

    1998-01-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source 102, a light reflecting surface 108, and a family of light edge rays defined along a reference line 104 with the reflecting surface 108 defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  6. Nonimaging optical illumination system

    DOEpatents

    Winston, Roland; Ries, Harald

    1996-01-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source 102, a light reflecting surface 108, and a family of light edge rays defined along a reference line 104 with the reflecting surface 108 defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  7. Nonimaging Optical Illumination System

    DOEpatents

    Winston, Roland

    1994-02-22

    A nonimaging illumination or concentration optical device. An optical device is provided having a light source, a light reflecting surface with an opening and positioned partially around the light source which is opposite the opening of the light reflecting surface. The light reflecting surface is disposed to produce a substantially uniform intensity output with the reflecting surface defined in terms of a radius vector R.sub.i in conjunction with an angle .phi..sub.i between R.sub.i, a direction from the source and an angle .theta..sub.i between direct forward illumination and the light ray reflected once from the reflecting surface. R.sub.i varies as the exponential of tan (.phi..sub.i -.theta..sub.i)/2 integrated over .phi..sub.i.

  8. Trend towards low cost, low power, ultra-violet (UV) based biological agent detectors

    NASA Astrophysics Data System (ADS)

    Sickenberger, David

    2005-11-01

    Ultra-violet fluorescence remains a corner stone technique for the detection of biological agent aerosols. Historically, these UV based detectors have employed relatively costly and power demanding lasers that have influenced the exploitation of the technology to wider use. Recent advancements from the Defense Advanced Research Project Agency's (DARPA) Solid-state Ultra Violet Optical Sources (SUVOS) program has changed this. The UV light emitting diode (LED) devices based on Gallium Nitride offer a unique opportunity to produce small, low power, and inexpensive detectors. It may, in fact, be possible to extend the SUVOS technology into detectors that are potentially disposable. This report will present ongoing efforts to explore this possibility. It will present candidate UV fluorescence based detector designs along with the biological aerosol responses obtained from these designs.

  9. Smartphone based point-of-care detector of urine albumin

    NASA Astrophysics Data System (ADS)

    Cmiel, Vratislav; Svoboda, Ondrej; Koscova, Pavlina; Provaznik, Ivo

    2016-03-01

    Albumin plays an important role in human body. Its changed level in urine may indicate serious kidney disorders. We present a new point-of-care solution for sensitive detection of urine albumin - the miniature optical adapter for iPhone with in-built optical filters and a sample slot. The adapter exploits smart-phone flash to generate excitation light and camera to measure the level of emitted light. Albumin Blue 580 is used as albumin reagent. The proposed light-weight adapter can be produced at low cost using a 3D printer. Thus, the miniaturized detector is easy to use out of lab.

  10. Tests of a multichannel photometer based on silicon diode detectors

    NASA Technical Reports Server (NTRS)

    Borucki, William J.; Allen, L. E.; Taylor, S. W.; Torbet, E. B.; Schaefer, A. R.; Fowler, J.

    1988-01-01

    A breadboard photometer was constructed that demonstrates a precision of 2 times 10 to the 4th power in the laboratory and scintillation-limited performance when used with an 0.5 m aperture telescope. Because the detectors and preamps are not cooled, only stars with m sub v approx. less than 4 are bright enough to allow the photometer to attain a precision of 1 times 10 to the 3rd power for three minute observations with an 0.5 m aperature telescope. Cooling the telescope should allow much fainter stars to be observed. Increasing the aperture of the telescope will allow higher precision and the observation of fainter stars.

  11. Image quality in two phosphor-based flat panel digital radiographic detectors.

    PubMed

    Samei, Ehsan

    2003-07-01

    Two general types of phosphor screens are currently used in indirect digital radiographic systems: structured phosphor screens and turbid phosphor screens. The purpose of the study was to experimentally compare the image quality characteristics of two flat-panel digital radiography detectors with similar electronics and pixel sizes (0.127 mm), but otherwise equipped with the two types of screens (0.6-mm-thick structured CsI and Lanex Regular). The presampled modulation transfer functions (MTFs) of the detectors were assessed using an edge method. The noise power spectra (NPS) were measured by two-dimensional Fourier analysis of uniformly-exposed radiographs at 50-100 kVp with 19 mm added Al filtration. The detective quantum efficiencies (DQEs) were assessed from the MTF, the NPS, and estimates of the ideal signal-to-noise ratio. The MTF measures of the two detectors were generally similar above a spatial frequency of 2 mm(-1), with approximately 2.5 and approximately 3.8 mm(-1) spatial frequencies corresponding to 0.2 MTF and 0.1 MTF, respectively. Below 2 mm(-1), the MTF for the CsI-based detector was slightly higher by an average of 0.07. At 70 kVp, the measured DQE values in the diagonal (and axial) direction(s) at spatial frequencies of 0.15 mm(-1) and 2.5 mm(-1) were 78% (78%) and 26% (20%) for the CsI-based detector, and 20% (20%) and 7% (6%) for the Lanex-based detector, respectively. The comparative findings experimentally confirm that in indirect flat-panel detectors, structured phosphor screens provide a more favorable tradeoff between resolution and noise compared to turbid-phosphor screens, effectively increasing the detection efficiency of the detector without a negative impact on the detector's spatial resolution response. PMID:12906192

  12. AQUARIUS, the next generation mid-IR detector for ground-based astronomy

    NASA Astrophysics Data System (ADS)

    Ives, Derek; Finger, Gert; Jakob, Gerd; Eschbaumer, Siegfried; Mehrgan, Leander; Meyer, Manfred; Steigmeier, Joerg

    2012-07-01

    ESO has recently funded the development of the AQUARIUS detector at Raytheon Vision Systems, a new mega-pixel Si:As Impurity Band Conduction array for use in ground based astronomical applications at wavelengths between 3 - 28 μm. The array has been designed to have low noise, low dark current, switchable gain and be read out at very high frame rates. It has 64 individual outputs capable of pixel read rates of 3MHz, implying continuous data-rates in excess of 300 Mbytes/second. It is scheduled for deployment into the VISIR instrument at the VLT in 2012, for next generation VLTI instruments and base-lined for METIS, the mid-IR candidate instrument for the E-ELT. A new mid-IR test facility has been developed for AQUARIUS detector development which includes a low thermal background cryostat, high speed cryogenic pre-amplification and high speed data acquisition and detector operation at 5K. We report on all the major performance aspects of this new detector including conversion gain, read noise, dark generation rate, linearity, well capacity, pixel operability, low frequency noise, persistence and electrical cross-talk. We describe the many possible readout modes of this detector and their application. We also report on external issues with the operation of these detectors at such low temperatures. Finally we report on the electronic developments required to operate such a detector at the required high data rates and in a typical mid-IR instrument.

  13. Experimental and theoretical performance analysis for a CMOS-based high resolution image detector

    NASA Astrophysics Data System (ADS)

    Jain, Amit; Bednarek, Daniel R.; Rudin, Stephen

    2014-03-01

    Increasing complexity of endovascular interventional procedures requires superior x-ray imaging quality. Present stateof- the-art x-ray imaging detectors may not be adequate due to their inherent noise and resolution limitations. With recent developments, CMOS based detectors are presenting an option to fulfill the need for better image quality. For this work, a new CMOS detector has been analyzed experimentally and theoretically in terms of sensitivity, MTF and DQE. The detector (Dexela Model 1207, Perkin-Elmer Co., London, UK) features 14-bit image acquisition, a CsI phosphor, 75 μm pixels and an active area of 12 cm x 7 cm with over 30 fps frame rate. This detector has two modes of operations with two different full-well capacities: high and low sensitivity. The sensitivity and instrumentation noise equivalent exposure (INEE) were calculated for both modes. The detector modulation-transfer function (MTF), noise-power spectra (NPS) and detective quantum efficiency (DQE) were measured using an RQA5 spectrum. For the theoretical performance evaluation, a linear cascade model with an added aliasing stage was used. The detector showed excellent linearity in both modes. The sensitivity and the INEE of the detector were found to be 31.55 DN/μR and 0.55 μR in high sensitivity mode, while they were 9.87 DN/μR and 2.77 μR in low sensitivity mode. The theoretical and experimental values for the MTF and DQE showed close agreement with good DQE even at fluoroscopic exposure levels. In summary, the Dexela detector's imaging performance in terms of sensitivity, linear system metrics, and INEE demonstrates that it can overcome the noise and resolution limitations of present state-of-the-art x-ray detectors.

  14. Reproducibility and calibration of MMC-based high-resolution gamma detectors

    DOE PAGESBeta

    Bates, C. R.; Pies, C.; Kempf, S.; Hengstler, D.; Fleischmann, A.; Gastaldo, L.; Enss, C.; Friedrich, S.

    2016-07-15

    Here, we describe a prototype γ-ray detector based on a metallic magnetic calorimeter with an energy resolution of 46 eV at 60 keV and a reproducible response function that follows a simple second-order polynomial. The simple detector calibration allows adding high-resolution spectra from different pixels and different cool-downs without loss in energy resolution to determine γ-ray centroids with high accuracy. As an example of an application in nuclear safeguards enabled by such a γ-ray detector, we discuss the non-destructive assay of 242Pu in a mixed-isotope Pu sample.

  15. Reproducibility and calibration of MMC-based high-resolution gamma detectors

    NASA Astrophysics Data System (ADS)

    Bates, C. R.; Pies, C.; Kempf, S.; Hengstler, D.; Fleischmann, A.; Gastaldo, L.; Enss, C.; Friedrich, S.

    2016-07-01

    We describe a prototype γ-ray detector based on a metallic magnetic calorimeter with an energy resolution of 46 eV at 60 keV and a reproducible response function that follows a simple second-order polynomial. The simple detector calibration allows adding high-resolution spectra from different pixels and different cool-downs without loss in energy resolution to determine γ-ray centroids with high accuracy. As an example of an application in nuclear safeguards enabled by such a γ-ray detector, we discuss the non-destructive assay of 242Pu in a mixed-isotope Pu sample.

  16. A V-BLAST Detector Based on Modified Householder QRD over the Spatially Correlated Fading Channel

    NASA Astrophysics Data System (ADS)

    Jing, Xiaorong; Zhou, Zhengzhong; Zhang, Tianqi

    We propose a feasible V-BLAST detector based on modified Householder QRD (M-H-QRD) over spatially correlated fading channel, which can almost match the performance of the V-BLAST algorithm with much lower complexity and better numerical stability. Compared to the sorted QRD (S-QRD) detector, the proposed detector requires a smaller minimum word-length to reach the same value of error floor for fixed-point (FP) numerical precision despite no significant performance difference for floating-point machine precision. All these advantages make it attractive when implemented using FP arithmetic.

  17. Microwave detectors based on the spin-torque diode effect

    NASA Astrophysics Data System (ADS)

    Prokopenko, O. V.; Slavin, A. N.

    2015-05-01

    The spin-transfer torque (STT) effect provides a new method of manipulation of magnetization in nanoscale objects. The STT effect manifests itself as a transfer of spin angular momentum between the parallel magnetic layers separated by a nonmagnetic spacer and traversed by a dc electric current. The transfer of the spin angular momentum from one layer to another could result in the excitation of the microwave-frequency magnetization dynamics in one of the magnetic layers. On the other hand, when a magnetization dynamics is excited in a magnetic layered structure by an external microwave signal both the structure electrical resistance and current through the structure will acquire microwave components resulting in the appearance of a rectified dc voltage on the magnetic structure. This "spin-torque diode effect" can be used for the development of ultra-sensitive spin-torque microwave detectors (STMD). Below we present a brief review of our recent work on the general properties of STMDs, analyze the performance of the "resonance-type" and "threshold-type STMD" and consider the possible applications for such microwave detectors.

  18. High-nitrogen-based pyrotechnics: longer- and brighter-burning, perchlorate-free, red-light illuminants for military and civilian applications.

    PubMed

    Sabatini, Jesse J; Nagori, Amita V; Chen, Gary; Chu, Phillip; Damavarapu, Reddy; Klapötke, Thomas M

    2012-01-01

    The full-up prototype testing of perchlorate-free, hand-held, signal illuminants for the US Army's M126A1 red star parachute hand-held signal is described. Compared to the perchlorate-containing control, the disclosed illuminants yielded excellent stabilities toward various ignition stimuli while offering superior pyrotechnic performance. Militarily, the illuminants provided further evidence that development of smaller hand-held signal items in an environmentally conscious way is a realistic and obtainable goal. The results are also important from the perspective of civilian fireworks, as the development of brighter, longer-burning, and environmentally compatible red-light-emitting pyrotechnics is now possible. PMID:22161957

  19. Novel illumination architectures based on nonimaging optics for low visual ground signature rapid deployment aircraft landing director

    NASA Astrophysics Data System (ADS)

    Lindsey, Lonnie; Savant, Gajendra D.; Jannson, Tomasz P.

    2000-08-01

    Traditional methods of marking aircraft landing zones during combat deployment operations range from simple reflective panels and colored smoke to the more elaborate strobe lighting systems and active radio frequency transceivers. Downed pilots, pathfinders, and special operations personnel are in jeopardy of detection by unfriendly ground forces, active location/direction devices act as beacons to foes as well as friends. Even passive devices can have unacceptable detection profiles. A highly directional fiber optic-based miniaturized landing director minimizes the more undesirable consequences of high profile directional devices.

  20. Highlight area inpainting guided by illumination model

    NASA Astrophysics Data System (ADS)

    Wang, Yifan; Jiang, Zhiguo; Shi, Jun

    2014-01-01

    In this paper, we proposed a two-step algorithm based on the combination of the exemplar-based algorithm and the illumination model to deal with specular images, especially those contain saturated pixels in the highlight areas. First the proposed modified exemplar-based algorithm is employed to process the unsaturated specular pixels under the supervision of illumination model. Then we inpaint the rest regions in which the pixels are saturated with original exemplar-based algorithm to obtain the final result. Experimental results demonstrate that the proposed algorithm performs better on the images with saturated pixels in the highlight areas compared with classical highlight removal and image inpainting algorithms.

  1. High dynamic range CMOS-based mammography detector for FFDM and DBT

    NASA Astrophysics Data System (ADS)

    Peters, Inge M.; Smit, Chiel; Miller, James J.; Lomako, Andrey

    2016-03-01

    Digital Breast Tomosynthesis (DBT) requires excellent image quality in a dynamic mode at very low dose levels while Full Field Digital Mammography (FFDM) is a static imaging modality that requires high saturation dose levels. These opposing requirements can only be met by a dynamic detector with a high dynamic range. This paper will discuss a wafer-scale CMOS-based mammography detector with 49.5 μm pixels and a CsI scintillator. Excellent image quality is obtained for FFDM as well as DBT applications, comparing favorably with a-Se detectors that dominate the X-ray mammography market today. The typical dynamic range of a mammography detector is not high enough to accommodate both the low noise and the high saturation dose requirements for DBT and FFDM applications, respectively. An approach based on gain switching does not provide the signal-to-noise benefits in the low-dose DBT conditions. The solution to this is to add frame summing functionality to the detector. In one X-ray pulse several image frames will be acquired and summed. The requirements to implement this into a detector are low noise levels, high frame rates and low lag performance, all of which are unique characteristics of CMOS detectors. Results are presented to prove that excellent image quality is achieved, using a single detector for both DBT as well as FFDM dose conditions. This method of frame summing gave the opportunity to optimize the detector noise and saturation level for DBT applications, to achieve high DQE level at low dose, without compromising the FFDM performance.

  2. Sn-based Ge/Ge0.975Sn0.025/Ge p-i-n photodetector operated with back-side illumination

    NASA Astrophysics Data System (ADS)

    Chang, C.; Li, H.; Huang, S. H.; Cheng, H. H.; Sun, G.; Soref, R. A.

    2016-04-01

    We report an investigation of a GeSn-based p-i-n photodetector grown on a Ge wafer that collects light signal from the back of the wafer. Temperature dependent absorption measurements performed over a wide temperature range (300 K down to 25 K) show that (a) absorption starts at the indirect bandgap of the active GeSn layer and continues up to the direct bandgap of the Ge wafer, and (b) the peak responsivity increases rapidly at first with decreasing temperature, then increases more slowly, followed by a decrease at the lower temperatures. The maximum responsivity happens at 125 K, which can easily be achieved with the use of liquid nitrogen. The temperature dependence of the photocurrent is analyzed by taking into consideration of the temperature dependence of the electron and hole mobility in the active layer, and the analysis result is in reasonable agreement with the data in the temperature regime where the rapid increase occurs. This investigation demonstrates the feasibility of a GeSn-based photodiode that can be operated with back-side illumination for applications in image sensing systems.

  3. Gamma-Free Neutron Detector Based upon Lithium Phosphate Nanoparticles

    SciTech Connect

    Steven Wallace

    2007-08-28

    A gamma-free neutron-sensitive scintillator is needed to enhance radiaition sensing and detection for nonproliferation applications. Such a scintillator would allow very large detectors to be placed at the perimeter of spent-fuel storage facilities at commercial nuclear power plants, so that any movement of spontaneously emitted neutrons from spent nuclear fuel or weapons grade plutonium would be noted in real-time. This task is to demonstrate that the technology for manufacturing large panels of fluor-doped plastic containing lithium-6 phosphate nanoparticles can be achieved. In order to detect neutrons, the nanoparticles must be sufficiently small so that the plastic remains transparent. In this way, the triton and alpha particles generated by the capture of the neutron will result in a photon burst that can be coupled to a wavelength shifting fiber (WLS) producing an optical signal of about ten nanoseconds duration signaling the presence of a neutron emitting source.

  4. A large area, silicon photomultiplier-based PET detector module

    PubMed Central

    Raylman, RR; Stolin, A; Majewski, S; Proffitt, J

    2013-01-01

    The introduction of silicon photomultipliers (SiPM) has facilitated construction of compact, efficient and magnetic field-hardened positron emission tomography (PET) scanners. To take full advantage of these devices, methods for using them to produce large field-of-view PET scanners are needed. In this investigation, we explored techniques to combine two SiPM arrays to form the building block for a small animal PET scanner. The module consists of a 26 × 58 array of 1.5 × 1.5mm2 LYSO elements (spanning 41 × 91mm2) coupled to two SensL SiPM arrays. The SiPMs were read out with new multiplexing electronics developed for this project. To facilitate calculation of event position with multiple SiPM arrays it was necessary to spread scintillation light amongst a number of elements with a small light guide. This method was successful in permitting identification of all detector elements, even at the seam between two SiPM arrays. Since the performance of SiPMs is enhanced by cooling, the detector module was fitted with a cooling jacket, which allowed the temperature of the device and electronics to be controlled. Testing demonstrated that the peak-to-valley contrast ratio of the light detected from the scintillation array was increased by ∼45% when the temperature was reduced from 28 °C to 16 °C. Energy resolution for 511 keV photons improved slightly from 18.8% at 28 °C to 17.8% at 16 °C. Finally, the coincidence timing resolution of the module was found to be insufficient for time-of-flight applications (∼2100 ps at 14 °C). The first use of these new modules will be in the construction of a small animal PET scanner to be integrated with a 3T clinical magnetic resonance imaging scanner. PMID:24319305

  5. A large area, silicon photomultiplier-based PET detector module

    NASA Astrophysics Data System (ADS)

    Raylman, R. R.; Stolin, A.; Majewski, S.; Proffitt, J.

    2014-01-01

    The introduction of silicon photomultipliers (SiPM) has facilitated construction of compact, efficient and magnetic field-hardened positron emission tomography (PET) scanners. To take full advantage of these devices, methods for using them to produce large field-of-view PET scanners are needed. In this investigation, we explored techniques to combine two SiPM arrays to form the building block for a small animal PET scanner. The module consists of a 26×58 array of 1.5×1.5 mm2 LYSO elements (spanning 41×91 mm2) coupled to two SensL SiPM arrays. The SiPMs were read out with new multiplexing electronics developed for this project. To facilitate calculation of event position with multiple SiPM arrays it was necessary to spread scintillation light amongst a number of elements with a small light guide. This method was successful in permitting identification of all detector elements, even at the seam between two SiPM arrays. Since the performance of SiPMs is enhanced by cooling, the detector module was fitted with a cooling jacket, which allowed the temperature of the device and electronics to be controlled. Testing demonstrated that the peak-to-valley contrast ratio of the light detected from the scintillation array was increased by ~45% when the temperature was reduced from 28 °C to 16 °C. Energy resolution for 511 keV photons improved slightly from 18.8% at 28 °C to 17.8% at 16 °C. Finally, the coincidence timing resolution of the module was found to be insufficient for time-of-flight applications (~2100 ps at 14 °C). The first use of these new modules will be in the construction of a small animal PET scanner to be integrated with a 3 T clinical magnetic resonance imaging scanner.

  6. Nonimaging Optical Illumination System

    DOEpatents

    Winston, Roland

    1994-08-02

    A nonimaging illumination optical device for producing selected intensity output over an angular range. The device includes a light reflecting surface (24, 26) around a light source (22) which is disposed opposite the aperture opening of the light reflecting surface (24, 26). The light source (22) has a characteristic dimension which is small relative to one or more of the distance from the light source (22) to the light reflecting surface (24, 26) or the angle subtended by the light source (22) at the light reflecting surface (24, 26).

  7. ILLUMINATION RESPONSE OF CDZNTE

    SciTech Connect

    Teague, L.; Washington, A.; Duff, M.

    2011-08-02

    CdZnTe (CZT) semiconducting crystals are of interest for use as room temperature X- and {gamma}-ray spectrometers. Several studies have focused on understanding the various electronic properties of these materials, such as the surface and bulk resistivities and the distribution of the electric field within the crystal. Specifically of interest is how these properties are influenced by a variety of factors including structural heterogeneities, such as secondary phases (SPs) and line defects as well as environmental effects. Herein, we report the bulk current, surface current, electric field distribution and performance of a spectrometer-grade CZT crystal exposed to above band-gap energy illumination.

  8. Illumination-compensated non-contact imaging photoplethysmography via dual-mode temporally coded illumination

    NASA Astrophysics Data System (ADS)

    Amelard, Robert; Scharfenberger, Christian; Wong, Alexander; Clausi, David A.

    2015-03-01

    Non-contact camera-based imaging photoplethysmography (iPPG) is useful for measuring heart rate in conditions where contact devices are problematic due to issues such as mobility, comfort, and sanitation. Existing iPPG methods analyse the light-tissue interaction of either active or passive (ambient) illumination. Many active iPPG methods assume the incident ambient light is negligible to the active illumination, resulting in high power requirements, while many passive iPPG methods assume near-constant ambient conditions. These assumptions can only be achieved in environments with controlled illumination and thus constrain the use of such devices. To increase the number of possible applications of iPPG devices, we propose a dual-mode active iPPG system that is robust to changes in ambient illumination variations. Our system uses a temporally-coded illumination sequence that is synchronized with the camera to measure both active and ambient illumination interaction for determining heart rate. By subtracting the ambient contribution, the remaining illumination data can be attributed to the controlled illuminant. Our device comprises a camera and an LED illuminant controlled by a microcontroller. The microcontroller drives the temporal code via synchronizing the frame captures and illumination time at the hardware level. By simulating changes in ambient light conditions, experimental results show our device is able to assess heart rate accurately in challenging lighting conditions. By varying the temporal code, we demonstrate the trade-off between camera frame rate and ambient light compensation for optimal blood pulse detection.

  9. Monte Carlo based performance assessment of different animal PET architectures using pixellated CZT detectors

    NASA Astrophysics Data System (ADS)

    Visvikis, D.; Lefevre, T.; Lamare, F.; Kontaxakis, G.; Santos, A.; Darambara, D.

    2006-12-01

    The majority of present position emission tomography (PET) animal systems are based on the coupling of high-density scintillators and light detectors. A disadvantage of these detector configurations is the compromise between image resolution, sensitivity and energy resolution. In addition, current combined imaging devices are based on simply placing back-to-back and in axial alignment different apparatus without any significant level of software or hardware integration. The use of semiconductor CdZnTe (CZT) detectors is a promising alternative to scintillators for gamma-ray imaging systems. At the same time CZT detectors have the potential properties necessary for the construction of a truly integrated imaging device (PET/SPECT/CT). The aims of this study was to assess the performance of different small animal PET scanner architectures based on CZT pixellated detectors and compare their performance with that of state of the art existing PET animal scanners. Different scanner architectures were modelled using GATE (Geant4 Application for Tomographic Emission). Particular scanner design characteristics included an overall cylindrical scanner format of 8 and 24 cm in axial and transaxial field of view, respectively, and a temporal coincidence window of 8 ns. Different individual detector modules were investigated, considering pixel pitch down to 0.625 mm and detector thickness from 1 to 5 mm. Modified NEMA NU2-2001 protocols were used in order to simulate performance based on mouse, rat and monkey imaging conditions. These protocols allowed us to directly compare the performance of the proposed geometries with the latest generation of current small animal systems. Results attained demonstrate the potential for higher NECR with CZT based scanners in comparison to scintillator based animal systems.

  10. Prototyping of MWIR MEMS-based optical filter combined with HgCdTe detector

    NASA Astrophysics Data System (ADS)

    Kozak, Dmitry A.; Fernandez, Bautista; Velicu, Silviu; Kubby, Joel

    2010-02-01

    In the past decades, there have been several attempts to create a tunable optical detector with operation in the infrared. The drive for creating such a filter is its wide range of applications, from passive night vision to biological and chemical sensors. Such a device would combine a tunable optical filter with a wide-range detector. In this work, we propose using a Fabry-Perot interferometer centered in the mid-wave infrared (MWIR) spectrum with an HgCdTe detector. Using a MEMS-based interferometer with an integrated Bragg stack will allow in-plane operation over a wide range. Because such devices have a tendency to warp, creating less-than-perfect optical surfaces, the Fabry-Perot interferometer is prototyped using the SOI-MUMPS process to ensure desirable operation. The mechanical design is aimed at optimal optical flatness of the moving membranes and a low operating voltage. The prototype is tested for these requirements. An HgCdTe detector provides greater performance than a pyroelectic detector used in some previous work, allowing for lower noise, greater detection speed and higher sensitivity. Both a custom HgCdTe detector and commercially available pyroelectric detector are tested with commercial optical filter. In previous work, monolithic integration of HgCdTe detectors with optical filters proved to be problematic. Part of this work investigates the best approach to combining these two components, either monolithically in HgCdTe or using a hybrid packaging approach where a silicon MEMS Fabry-Perot filter is bonded at low temperature to a HgCdTe detector.

  11. Microwave quantum illumination.

    PubMed

    Barzanjeh, Shabir; Guha, Saikat; Weedbrook, Christian; Vitali, David; Shapiro, Jeffrey H; Pirandola, Stefano

    2015-02-27

    Quantum illumination is a quantum-optical sensing technique in which an entangled source is exploited to improve the detection of a low-reflectivity object that is immersed in a bright thermal background. Here, we describe and analyze a system for applying this technique at microwave frequencies, a more appropriate spectral region for target detection than the optical, due to the naturally occurring bright thermal background in the microwave regime. We use an electro-optomechanical converter to entangle microwave signal and optical idler fields, with the former being sent to probe the target region and the latter being retained at the source. The microwave radiation collected from the target region is then phase conjugated and upconverted into an optical field that is combined with the retained idler in a joint-detection quantum measurement. The error probability of this microwave quantum-illumination system, or quantum radar, is shown to be superior to that of any classical microwave radar of equal transmitted energy. PMID:25768743

  12. Parallel hierarchical global illumination

    SciTech Connect

    Snell, Q.O.

    1997-10-08

    Solving the global illumination problem is equivalent to determining the intensity of every wavelength of light in all directions at every point in a given scene. The complexity of the problem has led researchers to use approximation methods for solving the problem on serial computers. Rather than using an approximation method, such as backward ray tracing or radiosity, the authors have chosen to solve the Rendering Equation by direct simulation of light transport from the light sources. This paper presents an algorithm that solves the Rendering Equation to any desired accuracy, and can be run in parallel on distributed memory or shared memory computer systems with excellent scaling properties. It appears superior in both speed and physical correctness to recent published methods involving bidirectional ray tracing or hybrid treatments of diffuse and specular surfaces. Like progressive radiosity methods, it dynamically refines the geometry decomposition where required, but does so without the excessive storage requirements for ray histories. The algorithm, called Photon, produces a scene which converges to the global illumination solution. This amounts to a huge task for a 1997-vintage serial computer, but using the power of a parallel supercomputer significantly reduces the time required to generate a solution. Currently, Photon can be run on most parallel environments from a shared memory multiprocessor to a parallel supercomputer, as well as on clusters of heterogeneous workstations.

  13. Lightness constancy and illumination discounting.

    PubMed

    Logvinenko, Alexander D; Tokunaga, Rumi

    2011-08-01

    effect of articulation. This leads to the conclusion that inexperienced observers are unable to estimate both the brightness and the luminance contrast of the light reflected from real objects lit by real lights. None of our observers perceived illumination edges purely as illumination edges: A partial Gelb effect ("partial illumination discounting") always took place. The lightness inconstancy in our experiment resulted from this partial illumination discounting. We propose an account of our results based on the two-dimensionality of achromatic colour. We argue that large interindividual variations and the effect of articulation are caused by the large ambiguity of luminance ratios in the stimulus displays used in laboratory conditions. PMID:21688072

  14. Applications of TM polarized illumination

    NASA Astrophysics Data System (ADS)

    Smith, Bruce; Zhou, Jianming; Xie, Peng

    2008-03-01

    The use of transverse electric (TE) polarization has dominated illumination schemes as selective polarization is used for high-NA patterning. The benefits of TE polarization are clear - the interference of diffracted beams remains absolute at oblique angles. Transverse magnetic (TM) polarization is usually considered less desirable as imaging modulation from interference at large angle falls off rapidly as the 1/cosθ. Significant potential remains, however, for the use of TM polarization at large angles when its reflection component is utilized. By controlling the resist/substrate interface reflectivity, high modulation for TM polarization can be maintained for angles up to 90° in the resist. This can potentially impact the design of illumination away from most recent TE-only schemes for oblique imaging angles (high NA). We demonstrate several cases of TM illumination combined with tuned substrate reflectivity for 0.93NA, 1.20NA, and 1.35NA and compare results to TE and unpolarized cases. The goal is to achieve a flat response through polarization at large imaging angles. An additional application of TM illumination is its potential use for double patterning. As double patterning and double exposure approaches are sought in order to meet the needs of 32nm device generations and beyond, materials and process engineering challenges become prohibitive. We have devised a method for frequency doubling in a single exposure using an unconventional means of polarization selection and by making use of the reflective component produced at the photoresist/substrate interface. In doing so, patterns can be deposited into a photoresist film with double density. As an example, using a projection system numerical aperture of 1.20, with water as an immersion fluid, and a conventional polyacrylate 193nm photoresist, pattern resolution at 20nm half-pitch are obtainable (which is 0.125lambda/NA). The process to transfer this geometry into a hardmask layer uses conventional materials

  15. GaN-Based Detector Enabling Technology for Next Generation Ultraviolet Planetary Missions

    NASA Technical Reports Server (NTRS)

    Aslam, S.; Gronoff, G.; Hewagama, T.; Janz, S.; Kotecki, C.

    2012-01-01

    The ternary alloy AlN-GaN-InN system provides several distinct advantages for the development of UV detectors for future planetary missions. First, (InN), (GaN) and (AlN) have direct bandgaps 0.8, 3.4 and 6.2 eV, respectively, with corresponding wavelength cutoffs of 1550 nm, 365 nm and 200 nm. Since they are miscible with each other, these nitrides form complete series of indium gallium nitride (In(sub l-x)Ga(sub x)N) and aluminum gallium nitride (Al(sub l-x)Ga(sub x)N) alloys thus allowing the development of detectors with a wavelength cut-off anywhere in this range. For the 2S0-365 nm spectral wavelength range AlGaN detectors can be designed to give a 1000x solar radiation rejection at cut-off wavelength of 325 nm, than can be achieved with Si based detectors. For tailored wavelength cut-offs in the 365-4S0 nm range, InGaN based detectors can be fabricated, which still give 20-40x better solar radiation rejection than Si based detectors. This reduced need for blocking filters greatly increases the Detective Quantum efficiency (DQE) and simplifies the instrument's optical systems. Second, the wide direct bandgap reduces the thermally generated dark current to levels allowing many observations to be performed at room temperature. Third, compared to narrow bandgap materials, wide bandgap semiconductors are significantly more radiation tolerant. Finally, with the use of an (AI, In)GaN array, the overall system cost is reduced by eliminating stringent Si CCD cooling systems. Compared to silicon, GaN based detectors have superior QE based on a direct bandgap and longer absorption lengths in the UV.

  16. Nanosecond X-ray detector based on high resistivity ZnO single crystal semiconductor

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaolong; Chen, Liang; He, Yongning; Liu, Jinliang; Peng, Wenbo; Huang, Zhiyong; Qi, Xiaomeng; Pan, Zijian; Zhang, Wenting; Zhang, Zhongbing; Ouyang, Xiaoping

    2016-04-01

    The pulse radiation detectors are sorely needed in the fields of nuclear reaction monitoring, material analysis, astronomy study, spacecraft navigation, and space communication. In this work, we demonstrate a nanosecond X-ray detector based on ZnO single crystal semiconductor, which emerges as a promising compound-semiconductor radiation detection material for its high radiation tolerance and advanced large-size bulk crystal growth technique. The resistivity of the ZnO single crystal is as high as 1013 Ω cm due to the compensation of the donor defects (VO) and acceptor defects (VZn and Oi) after high temperature annealing in oxygen. The photoconductive X-ray detector was fabricated using the high resistivity ZnO single crystal. The rise time and fall time of the detector to a 10 ps pulse electron beam are 0.8 ns and 3.3 ns, respectively, indicating great potential for ultrafast X-ray detection applications.

  17. Near midplane scintillator-based fast ion loss detector on DIII-D

    SciTech Connect

    Chen, X.; Heidbrink, W. W.; Fisher, R. K.; Pace, D. C.; Chavez, J. A.; Van Zeeland, M. A.; Garcia-Munoz, M.

    2012-10-15

    A new scintillator-based fast-ion loss detector (FILD) installed near the outer midplane of the plasma has been commissioned on DIII-D. This detector successfully measures coherent fast ion losses produced by fast-ion driven instabilities ({<=}500 kHz). Combined with the first FILD at {approx}45 Degree-Sign below the outer midplane [R. K. Fisher, et al., Rev. Sci. Instrum. 81, 10D307 (2010)], the two-detector system measures poloidal variation of losses. The phase space sensitivity of the new detector (gyroradius r{sub L}{approx}[1.5-8] cm and pitch angle {alpha}{approx}[35 Degree-Sign -85 Degree-Sign ]) is calibrated using neutral beam first orbit loss measurements. Since fast ion losses are localized poloidally, having two FILDs at different poloidal locations allows for the study of losses over a wider range of plasma shapes and types of loss orbits.

  18. Calibration method for spectral responsivity of infrared detector based on blackbody at multiple temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Y. F.; Shao, Z. F.; Wu, Y. Q.

    2015-08-01

    The spectral responsivity is one of the most important technical indicators of infrared detector which has an important significance for radiation thermometry and emissivity measurement. Using a blackbody radiation at multiple temperatures, the calibration for spectral responsivity of the infrared detector is proposed. With the Planck's law, the spectral radiance of blackbody at the different temperature is calculated. The detector captures the radiation and generates output values each of those is the function of spectral responsivity, spectral radiance and environmental radiation. Calibration equation is established by means of the calculated radiance and output values. By solving the equations based on principle of least squares, the calibration of spectral responsivity is implemented. From the comparison experiment of measuring the radiance of blackbody at 850K, radiance value measured by the MCT detector has a good consistency with the theoretical data.

  19. Optimization of a bolometer detector for ITER based on Pt absorber on SiN membrane.

    PubMed

    Meister, H; Eich, T; Endstrasser, N; Giannone, L; Kannamüller, M; Kling, A; Koll, J; Trautmann, T; Detemple, P; Schmitt, S

    2010-10-01

    Any plasma diagnostic in ITER must be able to operate at temperatures in excess of 200 °C and neutron loads corresponding to 0.1 dpa over its lifetime. To achieve this aim for the bolometer diagnostic, a miniaturized metal resistor bolometer detector based on Pt absorbers galvanically deposited on SiN membranes is being developed. The first two generations of detectors featured up to 4.5 μm thick absorbers. Results from laboratory tests are presented characterizing the dependence of their calibration constants under thermal loads up to 450 °C. Several detectors have been tested in ASDEX Upgrade providing reliable data but also pointing out the need for further optimization. A laser trimming procedure has been implemented to reduce the mismatch in meander resistances below 1% for one detector and the thermal drifts from this mismatch. PMID:21061487

  20. A Hybrid Multiuser Detector Based on MMSE and AFSA for TDRS System Forward Link

    PubMed Central

    Yin, Zhendong; Liu, Xiaohui

    2014-01-01

    This study mainly focuses on multiuser detection in tracking and data relay satellite (TDRS) system forward link. Minimum mean square error (MMSE) is a low complexity multiuser detection method, but MMSE detector cannot achieve satisfactory bit error ratio and near-far resistance, whereas artificial fish swarm algorithm (AFSA) is expert in optimization and it can realize the global convergence efficiently. Therefore, a hybrid multiuser detector based on MMSE and AFSA (MMSE-AFSA) is proposed in this paper. The result of MMSE and its modified formations are used as the initial values of artificial fishes to accelerate the speed of global convergence and reduce the iteration times for AFSA. The simulation results show that the bit error ratio and near-far resistance performances of the proposed detector are much better, compared with MF, DEC, and MMSE, and are quite close to OMD. Furthermore, the proposed MMSE-AFSA detector also has a large system capacity. PMID:24883418

  1. Multi-class geospatial object detection and geographic image classification based on collection of part detectors

    NASA Astrophysics Data System (ADS)

    Cheng, Gong; Han, Junwei; Zhou, Peicheng; Guo, Lei

    2014-12-01

    The rapid development of remote sensing technology has facilitated us the acquisition of remote sensing images with higher and higher spatial resolution, but how to automatically understand the image contents is still a big challenge. In this paper, we develop a practical and rotation-invariant framework for multi-class geospatial object detection and geographic image classification based on collection of part detectors (COPD). The COPD is composed of a set of representative and discriminative part detectors, where each part detector is a linear support vector machine (SVM) classifier used for the detection of objects or recurring spatial patterns within a certain range of orientation. Specifically, when performing multi-class geospatial object detection, we learn a set of seed-based part detectors where each part detector corresponds to a particular viewpoint of an object class, so the collection of them provides a solution for rotation-invariant detection of multi-class objects. When performing geographic image classification, we utilize a large number of pre-trained part detectors to discovery distinctive visual parts from images and use them as attributes to represent the images. Comprehensive evaluations on two remote sensing image databases and comparisons with some state-of-the-art approaches demonstrate the effectiveness and superiority of the developed framework.

  2. A novel optical apparatus for the study of rolling contact wear/fatigue based on a high-speed camera and multiple-source laser illumination.

    PubMed

    Bodini, I; Sansoni, G; Lancini, M; Pasinetti, S; Docchio, F

    2016-08-01

    Rolling contact wear/fatigue tests on wheel/rail specimens are important to produce wheels and rails of new materials for improved lifetime and performance, which are able to operate in harsh environments and at high rolling speeds. This paper presents a novel non-invasive, all-optical system, based on a high-speed video camera and multiple laser illumination sources, which is able to continuously monitor the dynamics of the specimens used to test wheel and rail materials, in a laboratory test bench. 3D macro-topography and angular position of the specimen are simultaneously performed, together with the acquisition of surface micro-topography, at speeds up to 500 rpm, making use of a fast camera and image processing algorithms. Synthetic indexes for surface micro-topography classification are defined, the 3D macro-topography is measured with a standard uncertainty down to 0.019 mm, and the angular position is measured on a purposely developed analog encoder with a standard uncertainty of 2.9°. The very small camera exposure time enables to obtain blur-free images with excellent definition. The system will be described with the aid of end-cycle specimens, as well as of in-test specimens. PMID:27587125

  3. Optical multiple-image encryption based on the chaotic structured phase masks under the illumination of a vortex beam in the gyrator domain.

    PubMed

    Liansheng, Sui; Bei, Zhou; Xiaojuan, Ning; Ailing, Tian

    2016-01-11

    A novel multiple-image encryption scheme using the nonlinear iterative phase retrieval algorithm in the gyrator transform domain under the illumination of an optical vortex beam is proposed. In order to increase the randomness, the chaotic structured phase mask based on the logistic map, Fresnel zone plate and radial Hilbert mask is proposed. With the help of two chaotic phase masks, each plain image is encoded into two phase-only masks that are considered as the private keys by using the iterative phase retrieval process in the gyrator domain. Then, the second keys of all plain images are modulated into the ciphertext, which has the stationary white noise distribution. Due to the use of the chaotic structured phase masks, the problem of axis alignment in the optical setup can easily be solved. Two private keys are directly relative to the plain images, which makes that the scheme has high resistance against various potential attacks. Moreover, the use of the vortex beam that can integrates more system parameters as the additional keys into one phase mask can improve the security level of the cryptosystem, which makes the key space enlarged widely. Simulation results are given to verify the feasibility and robustness of the proposed encryption scheme. PMID:26832280

  4. A novel optical apparatus for the study of rolling contact wear/fatigue based on a high-speed camera and multiple-source laser illumination

    NASA Astrophysics Data System (ADS)

    Bodini, I.; Sansoni, G.; Lancini, M.; Pasinetti, S.; Docchio, F.

    2016-08-01

    Rolling contact wear/fatigue tests on wheel/rail specimens are important to produce wheels and rails of new materials for improved lifetime and performance, which are able to operate in harsh environments and at high rolling speeds. This paper presents a novel non-invasive, all-optical system, based on a high-speed video camera and multiple laser illumination sources, which is able to continuously monitor the dynamics of the specimens used to test wheel and rail materials, in a laboratory test bench. 3D macro-topography and angular position of the specimen are simultaneously performed, together with the acquisition of surface micro-topography, at speeds up to 500 rpm, making use of a fast camera and image processing algorithms. Synthetic indexes for surface micro-topography classification are defined, the 3D macro-topography is measured with a standard uncertainty down to 0.019 mm, and the angular position is measured on a purposely developed analog encoder with a standard uncertainty of 2.9°. The very small camera exposure time enables to obtain blur-free images with excellent definition. The system will be described with the aid of end-cycle specimens, as well as of in-test specimens.

  5. Characterization of InGaAs-based cameras for astronomical applications using a new VIS-NIR-SWIR detector test bench

    NASA Astrophysics Data System (ADS)

    Schindler, Karsten; Wolf, Jürgen; Krabbe, Alfred

    2014-07-01

    A new test bench for detector and camera characterization in the visible and near-infrared spectral range between 350 -2500 nm has been setup at the Max Planck Institute for Solar System Research (MPS). The detector under study is illuminated by an integrating sphere that is fed by a Czerny-Turner monochromator with quasi-monochromatic light. A quartz tungsten halogen lamp is used as a light source for the monochromator. Si- and InGaAs-based photodiodes have been calibrated against secondary reference standards at PTB (Germany), NPL (UK) and NRC (Canada) for precise spectral flux measurements. The test bench allows measurements of fundamental detector properties such as linearity of response, conversion gain, full well capacity, quantum efficiency (QE), fixed pattern noise and pixel response non-uniformity. The article will focus on the commissioning of the test bench and subsequent performance evaluation and characterization of a commercial camera system with a 640 x 480 InGaAs-detector, sensitive between 900 to 1650 nm. The study aimed at the potential use of InGaAs cameras in ground-based and airborne astronomical observations or as target acquisition and tracking cameras in the NIR supporting infrared observations at longer wavelengths, e.g. on SOFIA. An intended future application of the test bench in combination with an appropriate test dewar is the characterization of focal plane assemblies for imaging spectrometers on spacecraft missions, such as the VIS-SWIR channel of MAJIS, the Moons and Jupiter Imaging Spectrometer aboard JUICE (Jupiter Icy Moons Explorer).

  6. Long-distance entanglement-based quantum key distribution experiment using practical detectors.

    PubMed

    Takesue, Hiroki; Harada, Ken-Ichi; Tamaki, Kiyoshi; Fukuda, Hiroshi; Tsuchizawa, Tai; Watanabe, Toshifumi; Yamada, Koji; Itabashi, Sei-Ichi

    2010-08-01

    We report an entanglement-based quantum key distribution experiment that we performed over 100 km of optical fiber using a practical source and detectors. We used a silicon-based photon-pair source that generated high-purity time-bin entangled photons, and high-speed single photon detectors based on InGaAs/InP avalanche photodiodes with the sinusoidal gating technique. To calculate the secure key rate, we employed a security proof that validated the use of practical detectors. As a result, we confirmed the successful generation of sifted keys over 100 km of optical fiber with a key rate of 4.8 bit/s and an error rate of 9.1%, with which we can distill secure keys with a key rate of 0.15 bit/s. PMID:20721069

  7. Lunar Polar Illumination for Power Analysis

    NASA Technical Reports Server (NTRS)

    Fincannon, James

    2008-01-01

    This paper presents illumination analyses using the latest Earth-based radar digital elevation model (DEM) of the lunar south pole and an independently developed analytical tool. These results enable the optimum sizing of solar/energy storage lunar surface power systems since they quantify the timing and durations of illuminated and shadowed periods. Filtering and manual editing of the DEM based on comparisons with independent imagery were performed and a reduced resolution version of the DEM was produced to reduce the analysis time. A comparison of the DEM with lunar limb imagery was performed in order to validate the absolute heights over the polar latitude range, the accuracy of which affects the impact of long range, shadow-casting terrain. Average illumination and energy storage duration maps of the south pole region are provided for the worst and best case lunar day using the reduced resolution DEM. Average illumination fractions and energy storage durations are presented for candidate low energy storage duration south pole sites. The best site identified using the reduced resolution DEM required a 62 hr energy storage duration using a fast recharge power system. Solar and horizon terrain elevations as well as illumination fraction profiles are presented for the best identified site and the data for both the reduced resolution and high resolution DEMs compared. High resolution maps for three low energy storage duration areas are presented showing energy storage duration for the worst case lunar day, surface height, and maximum absolute surface slope.

  8. Color rendering indices in global illumination methods

    NASA Astrophysics Data System (ADS)

    Geisler-Moroder, David; Dür, Arne

    2009-02-01

    Human perception of material colors depends heavily on the nature of the light sources used for illumination. One and the same object can cause highly different color impressions when lit by a vapor lamp or by daylight, respectively. Based on state-of-the-art colorimetric methods we present a modern approach for calculating color rendering indices (CRI), which were defined by the International Commission on Illumination (CIE) to characterize color reproduction properties of illuminants. We update the standard CIE method in three main points: firstly, we use the CIELAB color space, secondly, we apply a Bradford transformation for chromatic adaptation, and finally, we evaluate color differences using the CIEDE2000 total color difference formula. Moreover, within a real-world scene, light incident on a measurement surface is composed of a direct and an indirect part. Neumann and Schanda1 have shown for the cube model that interreflections can influence the CRI of an illuminant. We analyze how color rendering indices vary in a real-world scene with mixed direct and indirect illumination and recommend the usage of a spectral rendering engine instead of an RGB based renderer for reasons of accuracy of CRI calculations.

  9. Highly Resolved Intravital Striped-illumination Microscopy of Germinal Centers

    PubMed Central

    Andresen, Volker; Sporbert, Anje

    2014-01-01

    Monitoring cellular communication by intravital deep-tissue multi-photon microscopy is the key for understanding the fate of immune cells within thick tissue samples and organs in health and disease. By controlling the scanning pattern in multi-photon microscopy and applying appropriate numerical algorithms, we developed a striped-illumination approach, which enabled us to achieve 3-fold better axial resolution and improved signal-to-noise ratio, i.e. contrast, in more than 100 µm tissue depth within highly scattering tissue of lymphoid organs as compared to standard multi-photon microscopy. The acquisition speed as well as photobleaching and photodamage effects were similar to standard photo-multiplier-based technique, whereas the imaging depth was slightly lower due to the use of field detectors. By using the striped-illumination approach, we are able to observe the dynamics of immune complex deposits on secondary follicular dendritic cells – on the level of a few protein molecules in germinal centers. PMID:24748007

  10. Adaptive non-uniformity correction method based on temperature for infrared detector array

    NASA Astrophysics Data System (ADS)

    Zhang, Zhijie; Yue, Song; Hong, Pu; Jia, Guowei; Lei, Bo

    2013-09-01

    The existence of non-uniformities in the responsitivity of the element array is a severe problem typical to common infrared detector. These non-uniformities result in a "curtain'' like fixed pattern noises (FPN) that appear in the image. Some random noise can be restrained by the method kind of equalization method. But the fixed pattern noise can only be removed by .non uniformity correction method. The produce of non uniformities of detector array is the combined action of infrared detector array, readout circuit, semiconductor device performance, the amplifier circuit and optical system. Conventional linear correction techniques require costly recalibration due to the drift of the detector or changes in temperature. Therefore, an adaptive non-uniformity method is needed to solve this problem. A lot factors including detectors and environment conditions variety are considered to analyze and conduct the cause of detector drift. Several experiments are designed to verify the guess. Based on the experiments, an adaptive non-uniformity correction method is put forward in this paper. The strength of this method lies in its simplicity and low computational complexity. Extensive experimental results demonstrate the disadvantage of traditional non-uniformity correct method is conquered by the proposed scheme.

  11. A MAPS Based Micro-Vertex Detector for the STAR Experiment

    NASA Astrophysics Data System (ADS)

    Schambach, Joachim; Anderssen, Eric; Contin, Giacomo; Greiner, Leo; Silber, Joe; Stezelberger, Thorsten; Sun, Xiangming; Szelezniak, Michal; Videbaek, Flemming; Vu, Chinh; Wieman, Howard; Woodmansee, Sam

    For the 2014 heavy ion run of RHIC a new micro-vertex detector called the Heavy Flavor Tracker (HFT) was installed in the STAR experiment. The HFT consists of three detector subsystems with various silicon technologies arranged in 4 approximately concentric cylinders close to the STAR interaction point designed to improve the STAR detector's vertex resolution and extend its measurement capabilities in the heavy flavor domain. The two innermost HFT layers are placed at radii of 2.8 cm and 8 cm from the beam line. These layers are constructed with 400 high resolution sensors based on CMOS Monolithic Active Pixel Sensor (MAPS) technology arranged in 10-sensor ladders mounted on 10 thin carbon fiber sectors to cover a total silicon area of 0.16 m2. Each sensor of this PiXeL ("PXL") sub-detector combines a pixel array of 928 rows and 960 columns with a 20.7 μm pixel pitch together with front-end electronics and zero-suppression circuitry in one silicon die providing a sensitive area of ˜3.8 cm2. This sensor architecture features 185.6 μs readout time and 170 mW/cm2 power dissipation. This low power dissipation allows the PXL detector to be air-cooled, and with the sensors thinned down to 50 μm results in a global material budget of only 0.4% radiation length per layer. A novel mechanical approach to detector insertion allows us to effectively install and integrate the PXL sub-detector within a 12 hour period during an on-going multi-month data taking period. The detector requirements, architecture and design, as well as the performance after installation, are presented in this paper.

  12. DDG4 A Simulation Framework based on the DD4hep Detector Description Toolkit

    NASA Astrophysics Data System (ADS)

    Frank, M.; Gaede, F.; Nikiforou, N.; Petric, M.; Sailer, A.

    2015-12-01

    The detector description is an essential component that has to be used to analyse and simulate data resulting from particle collisions in high energy physics experiments. Based on the DD4hep detector description toolkit a flexible and data driven simulation framework was designed using the Geant4 tool-kit. We present this framework and describe the guiding requirements and the architectural design, which was strongly driven by ease of use. The goal was, given an existing detector description, to simulate the detector response to particle collisions in high energy physics experiments with minimal effort, but not impose restrictions to support enhanced or improved behaviour. Starting from the ROOT based geometry implementation used by DD4hep an automatic conversion mechanism to Geant4 was developed. The physics response and the mechanism to input particle data from generators was highly formalized and can be instantiated on demand using known factory patterns. A palette of components to model the detector response is provided by default, but improved or more sophisticated components may easily be added using the factory pattern. Only the final configuration of the instantiated components has to be provided by end-users using either C++ or python scripting or an XML based description.

  13. AQUARIUS: the next generation mid-IR detector for ground-based astronomy, an update.

    NASA Astrophysics Data System (ADS)

    Ives, Derek; Finger, Gert; Jakob, Gerd; Beckmann, Udo

    2014-07-01

    ESO has already published data from a preliminary laboratory analysis on the new mid-IR detector, AQUARIUS, at the previous SPIE conference of 2012, held in Amsterdam2. This data analysis indicated that this new mid-IR Si:As IBC detector, from Raytheon Vision Systems, was an excellent astronomical detector when compared to previous generations of this detector type, specifically in terms of stability, read noise and cosmetic quality. Since that time, the detector has been deployed into the VISIR1 instrument at the VLT, with very mixed performance results, especially when used with the telescope secondary mirror, to chop between two areas of sky to do background subtraction and at the same time when many frames are co-added to improve the signal to noise performance. This is the typical mode of operation for a mid-IR instrument on a ground based telescope. Preliminary astronomical data analysis indicated that the new detector was a factor of two to three times less sensitive in terms of its signal to noise per unit time performance when directly compared to the old DRS detector that AQUARIUS was designed to replace. To determine the reason for this loss of sensitivity, the instrument was removed from the telescope and not offered to the ESO user community. A detector testing campaign was then initiated in our laboratory to determine the reasons for this loss of sensitivity, assuming that it was an issue with the new detector itself. This paper reports on our latest laboratory measurements to determine the reasons for this loss of sensitivity. We specifically report on indirect measurements made to measure the quantum efficiency of the detector, which can be difficult to measure directly. We also report on a little known source of noise, called Excess Low Frequency Noise (ELFN). Detailed analysis and testing has confirmed that this ELFN is the reason for the loss of instrument sensitivity. This has been proven by a re-commissioning phase at the telescope with the

  14. Software-Based Real-Time Acquisition and Processing of PET Detector Raw Data.

    PubMed

    Goldschmidt, Benjamin; Schug, David; Lerche, Christoph W; Salomon, André; Gebhardt, Pierre; Weissler, Bjoern; Wehner, Jakob; Dueppenbecker, Peter M; Kiessling, Fabian; Schulz, Volkmar

    2016-02-01

    In modern positron emission tomography (PET) readout architectures, the position and energy estimation of scintillation events (singles) and the detection of coincident events (coincidences) are typically carried out on highly integrated, programmable printed circuit boards. The implementation of advanced singles and coincidence processing (SCP) algorithms for these architectures is often limited by the strict constraints of hardware-based data processing. In this paper, we present a software-based data acquisition and processing architecture (DAPA) that offers a high degree of flexibility for advanced SCP algorithms through relaxed real-time constraints and an easily extendible data processing framework. The DAPA is designed to acquire detector raw data from independent (but synchronized) detector modules and process the data for singles and coincidences in real-time using a center-of-gravity (COG)-based, a least-squares (LS)-based, or a maximum-likelihood (ML)-based crystal position and energy estimation approach (CPEEA). To test the DAPA, we adapted it to a preclinical PET detector that outputs detector raw data from 60 independent digital silicon photomultiplier (dSiPM)-based detector stacks and evaluated it with a [(18)F]-fluorodeoxyglucose-filled hot-rod phantom. The DAPA is highly reliable with less than 0.1% of all detector raw data lost or corrupted. For high validation thresholds (37.1 ± 12.8 photons per pixel) of the dSiPM detector tiles, the DAPA is real time capable up to 55 MBq for the COG-based CPEEA, up to 31 MBq for the LS-based CPEEA, and up to 28 MBq for the ML-based CPEEA. Compared to the COG-based CPEEA, the rods in the image reconstruction of the hot-rod phantom are only slightly better separable and less blurred for the LS- and ML-based CPEEA. While the coincidence time resolution (∼ 500 ps) and energy resolution (∼12.3%) are comparable for all three CPEEA, the system sensitivity is up to 2.5 × higher for the LS- and ML-based CPEEA

  15. Development of a detector based on Silicon Drift Detectors for gamma-ray spectroscopy and imaging applications

    NASA Astrophysics Data System (ADS)

    Busca, P.; Butt, A. D.; Fiorini, C.; Marone, A.; Occhipinti, M.; Peloso, R.; Quaglia, R.; Bombelli, L.; Giacomini, G.; Piemonte, C.; Camera, F.; Giaz, A.; Million, B.; Nelms, N.; Shortt, B.

    2014-05-01

    This work deals with the development of a new gamma detector based on Silicon Drift Detectors (SDDs) to readout large LaBr3:Ce scintillators for gamma-ray spectroscopy and imaging applications. The research is supported by the European Space Agency through the Technology Research Programme (TRP) and by Istituto Nazionale di Fisica Nucleare (INFN) within the Gamma project. The SDDs, produced at Fondazione Bruno Kessler (FBK) semiconductor laboratories, are designed as monolithic arrays of 3 × 3 units, each one of an active area of 8 mm × 8 mm (overall area of 26 mm × 26 mm). The readout electronics and the architecture of the camera are briefly described and then first experimental results coupling the SDD array with a 1'' × 1'' LaBr3:Ce scintillator are reported. An energy resolution of 3% FWHM at 662 keV has been measured at -20°C, better than coupling the same scintillator with a photomultiplier tube. The same scintillator is also used to evaluate position sensitivity with a 1 mm collimated Cs-137 source. The main difficulty in determining the position of the gamma-ray interaction in the crystal is associated to the high thickness/diameter ratio of the crystal (1:1) and the use of reflectors on all lateral and top sides the crystal. This last choice enhances energy resolution but makes imaging capability more challenging because light is spread over all photodetectors. Preliminary results show that the camera is able to detect shifts in the measured signals, when the source is moved with steps of 5 mm. A modified version of the centroid method is finally implemented to evaluate the imaging capability of the system.

  16. DEPFET based x-ray detectors for the MIXS focal plane on BepiColombo

    NASA Astrophysics Data System (ADS)

    Treis, J.; Hälker, O.; Andricek, L.; Herrmann, S.; Heinzinger, K.; Lauf, T.; Lechner, P.; Lutz, G.; Mas-Hesse, J. M.; Porro, M.; Richter, R. H.; San Juan, J. L.; Schaller, G.; Schnecke, M.; Schopper, F.; Segneri, G.; Soltau, H.; Stevenson, T.; Strüder, L.; Whitford, C.

    2008-07-01

    DEPFET Macropixel detectors, based on the fusion of the combined Detector-Amplifier structure DEPFET with a silicon drift chamber (SDD) like drift ring structure, combine the excellent properties of the DEPFETs with the advantages of the drift detectors. As both device concepts rely on the principle of sideways depletion, a device entrance window with excellent properties is obtained at full depletion of the detector volume. DEPFET based focal plane arrays have been proposed for the Focal Plane Detectors for the MIXS (Mercury Imaging X-ray Spectrometer) instrument on BepiColombo, ESAs fifth cornerstone mission, with destination Mercury. MIXS uses a lightweight Wolter Type 1 mirror system to focus fluorescent radiation from the Mercury surface on the FPA detector, which yields the spatially resolved relative element abundance in Mercurys crust. In combination with the reference information from the Solar Intensity X-ray Spectrometer (SIXS), the element abundance can be measured quantitatively as well. The FPA needs to have an energy resolution better than 200 eV FWHM @ 1 keV and is required to cover an energy range from 0.5 keV to 10 keV, for a pixel size of 300 x 300 μm2. Main challenges for the instrument are the increase in leakage current due to a high level of radiation damage, and the limited cooling resources due to the difficult thermal environment in the mercury orbit. By applying an advanced cooling concept, using all available cooling power for the detector itself, and very high speed readout, the energy resolution requirement can be kept during the entire mission lifetime up to an end-of-life dose of ~ 3 × 1010 10 MeV p / cm2. The production of the first batch of flight devices has been finished at the MPI semiconductor laboratory, and first prototype modules have been built. The results of the first tests will be presented here.

  17. Split-illumination electron holography

    SciTech Connect

    Tanigaki, Toshiaki; Aizawa, Shinji; Suzuki, Takahiro; Park, Hyun Soon; Inada, Yoshikatsu; Matsuda, Tsuyoshi; Taniyama, Akira; Shindo, Daisuke; Tonomura, Akira

    2012-07-23

    We developed a split-illumination electron holography that uses an electron biprism in the illuminating system and two biprisms (applicable to one biprism) in the imaging system, enabling holographic interference micrographs of regions far from the sample edge to be obtained. Using a condenser biprism, we split an electron wave into two coherent electron waves: one wave is to illuminate an observation area far from the sample edge in the sample plane and the other wave to pass through a vacuum space outside the sample. The split-illumination holography has the potential to greatly expand the breadth of applications of electron holography.

  18. Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature

    NASA Astrophysics Data System (ADS)

    Villa, E.; Aja, B.; de la Fuente, L.; Artal, E.

    2016-01-01

    This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diode detector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diode detector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature.

  19. Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature.

    PubMed

    Villa, E; Aja, B; de la Fuente, L; Artal, E

    2016-01-01

    This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diode detector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diode detector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature. PMID:26827340

  20. Modified Anderson-Darling Test-Based Target Detector in Non-Homogenous Environments

    PubMed Central

    Li, Yang; Wei, Yinsheng; Li, Bingfei; Alterovitz, Gil

    2014-01-01

    A constant false alarm rate (CFAR) target detector in non-homogenous backgrounds is proposed. Based on K-sample Anderson-Darling (AD) tests, the method re-arranges the reference cells by merging homogenous sub-blocks surrounding the cell under test (CUT) into a new reference window to estimate the background statistics. Double partition test, clutter edge refinement and outlier elimination are used as an anti-clutter processor in the proposed Modified AD (MAD) detector. Simulation results show that the proposed MAD test based detector outperforms cell-averaging (CA) CFAR, greatest of (GO) CFAR, smallest of (SO) CFAR, order-statistic (OS) CFAR, variability index (VI) CFAR, and CUT inclusive (CI) CFAR in most non-homogenous situations. PMID:25177800

  1. Optimal color temperature adjustment for mobile devices under varying illuminants

    NASA Astrophysics Data System (ADS)

    Choi, Kyungah; Suk, Hyeon-Jeong

    2014-01-01

    With the wide use of mobile devices, display color reproduction has become extremely important. The purpose of this study is to investigate the optimal color temperature for mobile displays under varying illuminants. The effect of the color temperature and the illuminance of ambient lighting on user preferences were observed. For a visual examination, a total of 19 nuanced whites were examined under 20 illuminants. A total of 19 display stimuli with different color temperatures (2,500 K ~ 19,600 K) were presented on an iPad3 (New iPad). The ambient illuminants ranged in color temperature from 2,500 K to 19,800 K and from 0 lx to 3,000 lx in illuminance. Supporting previous studies of color reproduction, there was found to be a positive correlation between the color temperature of illuminants and that of optimal whites. However, the relationship was not linear. Based on assessments by 56 subjects, a regression equation was derived to predict the optimal color temperature adjustment under varying illuminants, as follows: [Display Tcp = 5138.93 log(Illuminant Tcp) - 11956.59, p<.001, R2=0.94]. Moreover, the influence of an illuminant was positively correlated with the illuminance level, confirming the findings of previous studies. It is expected that the findings of this study can be used as the theoretical basis when designing a color strategy for mobile display devices.

  2. Low-dose performance of wafer-scale CMOS-based X-ray detectors

    NASA Astrophysics Data System (ADS)

    Maes, Willem H.; Peters, Inge M.; Smit, Chiel; Kessener, Yves; Bosiers, Jan

    2015-03-01

    Compared to published amorphous-silicon (TFT) based X-ray detectors, crystalline silicon CMOS-based active-pixel detectors exploit the benefits of low noise, high speed, on-chip integration and featuring offered by CMOS technology. This presentation focuses on the specific advantage of high image quality at very low dose levels. The measurement of very low dose performance parameters like Detective Quantum Efficiency (DQE) and Noise Equivalent Dose (NED) is a challenge by itself. Second-order effects like defect pixel behavior, temporal and quantization noise effects, dose measurement accuracy and limitation of the x-ray source settings will influence the measurements at very low dose conditions. Using an analytical model to predict the low dose behavior of a detector from parameters extracted from shot-noise limited dose levels is presented. These models can also provide input for a simulation environment for optimizing the performance of future detectors. In this paper, models for predicting NED and the DQE at very low dose are compared to measurements on different CMOS detectors. Their validity for different sensor and optical stack combinations as well as for different x-ray beam conditions was validated.

  3. Growth and fabrication of sputtered TiO2 based ultraviolet detectors

    NASA Astrophysics Data System (ADS)

    Huang, Huolin; Xie, Yannan; Zhang, Zifeng; Zhang, Feng; Xu, Qiang; Wu, Zhengyun

    2014-02-01

    TiO2 films with high crystallinity and good stoichiometry were prepared by magnetron sputtering technique under the optimized process conditions and analyzed by various characterization methods. Metal-semiconductor-metal (MSM) structure detectors with diverse finger spacings were then fabricated on the TiO2 films by employing Au as the Schottky contact metal. Low dark current, large UV responsivity, and high UV-to-visible rejection ratio (310 versus 400 nm) were found in these detectors. In particular, the lowest dark current of 4.58 nA/cm2 at 5 V bias and the highest UV-to-visible rejection ratio of 3.52 × 103 were achieved in the detectors with 10 μm finger spacing which are comparable to the best results in the TiO2 based detectors reported to date. Considering the simple fabrication process and low cost, the sputtered TiO2 based MSM detectors are very promising in commercial production for the UV detection applications.

  4. Gamma-ray superconducting detector based on Abrikosov vortices: Principle of operation

    SciTech Connect

    Lisitskiy, M. P.

    2009-11-15

    The high atomic number of some superconducting elements such as niobium (Z=41) and tantalum (Z=73) and a high material thickness (e.g., t=300 mum) are emphasized as essential properties for development of a gamma-ray solid state detector with high intrinsic detection efficiency in the energy range up to 100 keV. To exploit these properties, a new detection principle based on the interaction of a single gamma-ray photon with Abrikosov vortex is proposed. The interaction of gamma-ray photon with a superconductor is discussed in terms of the photoelectric absorption and a hot-spot formation, the last acts as a short-time pinning center on an Abrikosov vortex and activates its motion, namely, a jump or damped vibration. Both types of vortex motion lead to variation (either static or dynamic) in the magnetic field on the absorber surface. The high sensitivity of the Josephson tunneling to weak magnetic field can be exploited for revealing the magnetic field variation and to make the readout of the detector. Main intrinsic properties of a gamma-ray detector based on Abrikosov vortices are evaluated, including the possibility to measure the energy deposited in the detector. A single Josephson tunnel junction configuration or a superconducting quantum interference device (SQUID) configuration is proposed and discussed as possible realization of working gamma-ray detector both in the counter operation mode and in the radiation spectroscopy operation mode.

  5. Development and characterization of a neutron detector based on a lithium glass-polymer composite

    NASA Astrophysics Data System (ADS)

    Mayer, M.; Nattress, J.; Kukharev, V.; Foster, A.; Meddeb, A.; Trivelpiece, C.; Ounaies, Z.; Jovanovic, I.

    2015-06-01

    We report on the fabrication and characterization of a neutron scintillation detector based on a Li-glass-polymer composite that utilizes a combination of pulse height and pulse shape discrimination (PSD) to achieve high gamma rejection. In contrast to fast neutron detection in a PSD medium, we combine two scintillating materials that do not possess inherent neutron/gamma PSD properties to achieve effective PSD/pulse height discrimination in a composite material. Unlike recoil-based fast neutron detection, neutron/gamma discrimination can be robust even at low neutron energies due to the high Q-value neutron capture on 6Li. A cylindrical detector with a 5.05 cm diameter and 5.08 cm height was fabricated from scintillating 1 mm diameter Li-glass rods and scintillating polyvinyltoluene. The intrinsic efficiency for incident fission neutrons from 252Cf and gamma rejection of the detector were measured to be 0.33% and less than 10-8, respectively. These results demonstrate the high selectivity of the detector for neutrons and provide motivation for prototyping larger detectors optimized for specific applications, such as detection and event-by-event spectrometry of neutrons produced by fission.

  6. Boron-coated straws as a replacement for 3He-based neutron detectors

    NASA Astrophysics Data System (ADS)

    Lacy, Jeffrey L.; Athanasiades, Athanasios; Sun, Liang; Martin, Christopher S.; Lyons, Tom D.; Foss, Michael A.; Haygood, Hal B.

    2011-10-01

    US and international government efforts to equip major seaports with large area neutron detectors, aimed to intercept the smuggling of nuclear materials, have precipitated a critical shortage of 3He gas. It is estimated that the annual demand of 3He for US security applications alone is more than the worldwide supply. This is strongly limiting the prospects of neutron science, safeguards, and other applications that rely heavily on 3He-based detectors. Clearly, alternate neutron detection technologies that can support large sensitive areas, and have low gamma sensitivity and low cost must be developed. We propose a low-cost technology based on long copper tubes (straws), coated on the inside with a thin layer of 10B-enriched boron carbide ( 10B 4C). In addition to the high abundance of boron on Earth and low cost of 10B enrichment, the boron-coated straw (BCS) detector offers distinct advantages over conventional 3He-based detectors, and alternate technologies such as 10BF 3 tubes and 10B-coated rigid tubes. These include better distribution inside moderator assemblies, many-times faster electronic signals, no pressurization, improved gamma-ray rejection, no toxic or flammable gases, and ease of serviceability. We present the performance of BCS detectors dispersed in a solid plastic moderator to address the need for portal monitoring. The design adopts the outer dimensions of currently deployed 3He-based monitors, but takes advantage of the small BCS diameter to achieve a more uniform distribution of neutron converter throughout the moderating material. We show that approximately 63 BCS detectors, each 205 cm long, distributed inside the moderator, can match or exceed the detection efficiency of typical monitors fitted with a 5 cm diameter 3He tube, 187 cm long, pressurized to 3 atm.

  7. Augmented 3D super-resolution of fluorescence-free nanoparticles using enhanced dark-field illumination based on wavelength-modulation and a least-cubic algorithm.

    PubMed

    Zhang, Peng; Kim, Kyungsoo; Lee, Seungah; Chakkarapani, Suresh Kumar; Fang, Ning; Kang, Seong Ho

    2016-01-01

    Augmented three-dimensional (3D) subdiffraction-limited resolution of fluorescence-free single-nanoparticles was achieved with wavelength-dependent enhanced dark-field (EDF) illumination and a least-cubic algorithm. Various plasmonic nanoparticles on a glass slide (i.e., gold nanoparticles, GNPs; silver nanoparticles, SNPs; and gold nanorods, GNRs) were imaged and sliced in the z-direction to a thickness of 10 nm. Single-particle images were then compared with simulation data. The 3D coordinates of individual GNP, SNP, and GNR nanoparticles (x, y, z) were resolved by fitting the data with 3D point spread functions using a least-cubic algorithm and collation. Final, 3D super-resolution microscopy (SRM) images were obtained by resolving 3D coordinates and their Cramér-Rao lower bound-based localization precisions in an image space (530 nm × 530 nm × 300 nm) with a specific voxel size (2.5 nm × 2.5 nm × 5 nm). Compared with the commonly used least-square method, the least-cubic method was more useful for finding the center in asymmetric cases (i.e., nanorods) with high precision and accuracy. This novel 3D fluorescence-free SRM technique was successfully applied to resolve the positions of various nanoparticles on glass and gold nanospots (in vitro) as well as in a living single cell (in vivo) with subdiffraction limited resolution in 3D. PMID:27619347

  8. Development of GAGG depth-of-interaction (DOI) block detectors based on pulse shape analysis

    NASA Astrophysics Data System (ADS)

    Yamamoto, Seiichi; Kobayashi, Takahiro; Yeol Yeom, Jung; Morishita, Yuki; Sato, Hiroki; Endo, Takanori; Usuki, Yoshiyuki; Kamada, Kei; Yoshikawa, Akira

    2014-12-01

    A depth-of-interaction (DOI) detector is required for developing a high resolution and high sensitivity PET system. Ce-doped Gd3Al2Ga3O12 (GAGG fast: GAGG-F) is a promising scintillator for PET applications with high light output, no natural radioisotope and suitable light emission wavelength for semiconductor based photodetectors. However, no DOI detector based on pulse shape analysis with GAGG-F has been developed to date, due to the lack of appropriate scintillators of pairing. Recently a new variation of this scintillator with different Al/Ga ratios-Ce-doped Gd3Al2.6Ga2.4O12 (GAGG slow: GAGG-S), which has slower decay time was developed. The combination of GAGG-F and GAGG-S may allow us to realize high resolution DOI detectors based on pulse shape analysis. We developed and tested two GAGG phoswich DOI block detectors comprised of pixelated GAGG-F and GAGG-S scintillation crystals. One phoswich block detector comprised of 2×2×5 mm pixel that were assembled into a 5×5 matrix. The DOI block was optically coupled to a silicon photomultiplier (Si-PM) array (Hamamatsu MPPC S11064-050P) with a 2-mm thick light guide. The other phoswich block detector comprised of 0.5×0.5×5 mm (GAGG-F) and 0.5×0.5×6 mm3 (GAGG-S) pixels that were assembled into a 20×20 matrix. The DOI block was also optically coupled to the same Si-PM array with a 2-mm thick light guide. In the block detector of 2-mm crystal pixels (5×5 matrix), the 2-dimensional histogram revealed excellent separation with an average energy resolution of 14.1% for 662-keV gamma photons. The pulse shape spectrum displayed good separation with a peak-to-valley ratio of 8.7. In the block detector that used 0.5-mm crystal pixels (20×20 matrix), the 2-dimensional histogram also showed good separation with energy resolution of 27.5% for the 662-keV gamma photons. The pulse shape spectrum displayed good separation with a peak-to-valley ratio of 6.5. These results indicate that phoswich DOI detectors with the two

  9. Assembling and Using an LED-Based Detector to Monitor Absorbance Changes during Acid-Base Titrations

    ERIC Educational Resources Information Center

    Santos, Willy G.; Cavalheiro, E´der T. G.

    2015-01-01

    A simple photometric assembly based in an LED as a light source and a photodiode as a detector is proposed in order to follow the absorbance changes as a function of the titrant volume added during the course of acid-base titrations in the presence of a suitable visual indicator. The simplicity and low cost of the electronic device allow the…

  10. Terrestrial detector for low frequency gravitational waves based on full tensor measurement

    NASA Astrophysics Data System (ADS)

    Lee, Hyung Mok; Paik, Hojung; Majorana, Ettore; Vol Moody, M.; Griggs, Cornelius E.; Nielsen, Alex; Kim, Chumglee

    2015-08-01

    Terrestrial gravitational wave (GW) detectors are mostly based on Michelson-type laser interferometers with arm lengths of a few km to reach a strain sensitivity of 10-23 Hz-1/2 in the frequency range of a few 100 to a few 1000 Hz. There should be a large variety of sources generating GWs at lower frequencies below 10 Hz. However, seismic and Newtonian noise has been serious obstacle in realizing terrestrial low-frequency GW detectors. Here we describe a new GW detector concept by adopting new measurement techniques and configurations to overcome the present low-frequency barrier due to seismic and Newtonian noise. The detector is an extension of the superconducting gravity gradiometer (SGG) that has been developed at the University of Maryland to measure all components of the gravity gradient tensor by orthogonally combining three bars with test masses at each end. The oscillating component of the gravity gradient tensor is the GW strain tensor, but the actual signal is likely to be dominated by Newtonian and seismic noise, whose amplitudes are several orders of magnitude larger than the GWs. We propose to mitigate seismic noise by (a) constructing detector in deep underground, (b) applying passive isolation with pendulum suspension, and (c) using the common-mode rejection characteristic of the detector. The Newtonian noise can be suppressed by combining the components of the gradient tensor with signals detected by seismometers and microphones. By constructing a detector of 100-m long bars cooled to 0.1 K, a strain sensitivity of a few times 10-21 Hz-1/2 can be achieved in the frequency range between 0.1 to 10 Hz. Binaries composed of intermediate mass black holes of 1000 to 10,000 M¤ could be detected at distances up to a few Gpc with this detector. Detectable range for the merging white dwarf binaries is up to a few Mpc. Unlike current two-dimensional detectors, our single detector is able to determine the polarization of GWs and the direction to sources on

  11. Timing in the NOvA detectors with atomic clock based time transfers between Fermilab, the Soudan mine and the NOvA Far detector

    NASA Astrophysics Data System (ADS)

    Norman, A.; Niner, E.; Habig, A.

    2015-12-01

    The NOvA experiment uses a GPS based timing system both to internally synchronize the readout of the DAQ components and to establish an absolute wall clock reference which can be used to link the Fermilab accelerator complex with the neutrino flux that crosses the NOvA detectors. We describe the methods that were used during the commissioning of the NOvA DAQ and Timing systems to establish the synchronization between the Fermilab beam and the NOvA far detector. We present how high precision atomic clocks were trained and transported between the MINOS and NOvA detectors during a Northern Minnesota blizzard to validate the absolute time offsets of the experiments and make the first observation of beam neutrinos in the NOvA far detector.

  12. A MAPS Based Micro-Vertex Detector for the STAR Experiment

    DOE PAGESBeta

    Schambach, Joachim; Anderssen, Eric; Contin, Giacomo; Greiner, Leo; Silber, Joe; Stezelberger, Thorsten; Sun, Xiangming; Szelezniak, Michal; Videbaek, Flemming; Vu, Chinh; et al

    2015-06-18

    For the 2014 heavy ion run of RHIC a new micro-vertex detector called the Heavy Flavor Tracker (HFT) was installed in the STAR experiment. The HFT consists of three detector subsystems with various silicon technologies arranged in 4 approximately concentric cylinders close to the STAR interaction point designed to improve the STAR detector’s vertex resolution and extend its measurement capabilities in the heavy flavor domain. The two innermost HFT layers are placed at radii of 2.8 cm and 8 cm from the beam line. These layers are constructed with 400 high resolution sensors based on CMOS Monolithic Active Pixel Sensormore » (MAPS) technology arranged in 10-sensor ladders mounted on 10 thin carbon fiber sectors to cover a total silicon area of 0.16 m2. Each sensor of this PiXeL (“PXL”) sub-detector combines a pixel array of 928 rows and 960 columns with a 20.7 μm pixel pitch together with front-end electronics and zero-suppression circuitry in one silicon die providing a sensitive area of ~3.8 cm2. This sensor architecture features 185.6 μs readout time and 170 mW/cm2 power dissipation. This low power dissipation allows the PXL detector to be air-cooled, and with the sensors thinned down to 50 μm results in a global material budget of only 0.4% radiation length per layer. A novel mechanical approach to detector insertion allows us to effectively install and integrate the PXL sub-detector within a 12 hour period during an on-going multi-month data taking period. The detector requirements, architecture and design, as well as the performance after installation, are presented in this paper.« less

  13. A MAPS Based Micro-Vertex Detector for the STAR Experiment

    SciTech Connect

    Schambach, Joachim; Anderssen, Eric; Contin, Giacomo; Greiner, Leo; Silber, Joe; Stezelberger, Thorsten; Sun, Xiangming; Szelezniak, Michal; Videbaek, Flemming; Vu, Chinh; Wieman, Howard; Woodmansee, Sam

    2015-06-18

    For the 2014 heavy ion run of RHIC a new micro-vertex detector called the Heavy Flavor Tracker (HFT) was installed in the STAR experiment. The HFT consists of three detector subsystems with various silicon technologies arranged in 4 approximately concentric cylinders close to the STAR interaction point designed to improve the STAR detector’s vertex resolution and extend its measurement capabilities in the heavy flavor domain. The two innermost HFT layers are placed at radii of 2.8 cm and 8 cm from the beam line. These layers are constructed with 400 high resolution sensors based on CMOS Monolithic Active Pixel Sensor (MAPS) technology arranged in 10-sensor ladders mounted on 10 thin carbon fiber sectors to cover a total silicon area of 0.16 m2. Each sensor of this PiXeL (“PXL”) sub-detector combines a pixel array of 928 rows and 960 columns with a 20.7 μm pixel pitch together with front-end electronics and zero-suppression circuitry in one silicon die providing a sensitive area of ~3.8 cm2. This sensor architecture features 185.6 μs readout time and 170 mW/cm2 power dissipation. This low power dissipation allows the PXL detector to be air-cooled, and with the sensors thinned down to 50 μm results in a global material budget of only 0.4% radiation length per layer. A novel mechanical approach to detector insertion allows us to effectively install and integrate the PXL sub-detector within a 12 hour period during an on-going multi-month data taking period. The detector requirements, architecture and design, as well as the performance after installation, are presented in this paper.

  14. Scene Illumination as an Indicator of Image Manipulation

    NASA Astrophysics Data System (ADS)

    Riess, Christian; Angelopoulou, Elli

    The goal of blind image forensics is to distinguish original and manipulated images. We propose illumination color as a new indicator for the assessment of image authenticity. Many images exhibit a combination of multiple illuminants (flash photography, mixture of indoor and outdoor lighting, etc.). In the proposed method, the user selects illuminated areas for further investigation. The illuminant colors are locally estimated, effectively decomposing the scene in a map of differently illuminated regions. Inconsistencies in such a map suggest possible image tampering. Our method is physics-based, which implies that the outcome of the estimation can be further constrained if additional knowledge on the scene is available. Experiments show that these illumination maps provide a useful and very general forensics tool for the analysis of color images.

  15. Solar illumination device

    SciTech Connect

    Eijadi, D.; Bennett, D.J.

    1986-06-10

    A solar concentrator is described for illuminating the interior of a building through a side wall thereof. The concentrator consists of: a stationary reflective collector located to view the sky and having discrete planar collector surfaces mounted in abutting relationship, the collector surface installed at an angle with respect to the vertical different from the angle of installation of the abutting collector surfaces; a stationary reflective reflector positioned to receive direct solar energy reflected by the collector and oriented to reflect such energy toward a target within the building, the reflector having a plurality of discrete planar reflector surfaces the reflector surface mounted in abutting relationship, the reflector surface installed at an angle with respect to the vertical different from the angle of installation of the abutting reflector surfaces; a low angle shield means for preventing direct solar rays from entering unreflected into the building between the collector and the reflector and penetrating a horizontal plane above the floor of the building, the horizontal plane spaced from the floor a distance substantially equal to the height of the eye of an occupant standing on the floor of the building, the low angle shield means including an opaque material and being affixed to the reflector; and a shield means for preventing rays reflected by the collector and the reflector from penetrating the horizontal plane, the shield means affixed to the building and extending in a generally horizontal direction.

  16. Evolution of Some Particle Detectors Based On the Discharge in Gases

    DOE R&D Accomplishments Database

    Charpak, G.

    1969-11-19

    Summary of the properties of some of the detectors that are commonly used in counter experiments to localize charged particles, and which are based on discharge in gases under the influence of electric fields and some basic facts of gaseous amplification in homogeneous and inhomogeneous fields.

  17. A Real Valued Neural Network Based Autoregressive Energy Detector for Cognitive Radio Application.

    PubMed

    Onumanyi, A J; Onwuka, E N; Aibinu, A M; Ugweje, O C; Salami, M J E

    2014-01-01

    A real valued neural network (RVNN) based energy detector (ED) is proposed and analyzed for cognitive radio (CR) application. This was developed using a known two-layered RVNN model to estimate the model coefficients of an autoregressive (AR) system. By using appropriate modules and a well-designed detector, the power spectral density (PSD) of the AR system transfer function was estimated and subsequent receiver operating characteristic (ROC) curves of the detector generated and analyzed. A high detection performance with low false alarm rate was observed for varying signal to noise ratio (SNR), sample number, and model order conditions. The proposed RVNN based ED was then compared to the simple periodogram (SP), Welch periodogram (WP), multitaper (MT), Yule-Walker (YW), Burg (BG), and covariance (CV) based ED techniques. The proposed detector showed better performance than the SP, WP, and MT while providing better false alarm performance than the YW, BG, and CV. Data provided here support the effectiveness of the proposed RVNN based ED for CR application. PMID:27379318

  18. Development of a thermal neutron detector based on scintillating fibers and silicon photomultipliers

    SciTech Connect

    Barbagallo, Massimo; Greco, Giuseppe; Scire, Carlotta; Scire, Sergio; Cosentino, Luigi; Pappalardo, Alfio; Finocchiaro, Paolo; Montereali, Rosa Maria; Vincenti, Maria Aurora

    2010-09-15

    We propose a technique for thermal neutron detection, based on a {sup 6}Li converter placed in front of scintillating fibers readout by means of silicon photomultipliers. Such a technique allows building cheap and compact detectors and dosimeters, thus possibly opening new perspectives in terms of granular monitoring of neutron fluxes as well as space-resolved neutron detection.

  19. A Low-Cost Liquid-Chromatography System Using a Spectronic 20-Based Detector.

    ERIC Educational Resources Information Center

    Jezorek, John R.; And Others

    1986-01-01

    Describes the design and evaluation of a Spectronic 20-based detector as well as a simple system for postcolumn derivatization useful for metal-ion chromatographic detection. Both detection and derivatization can be performed in the ultra-violet (UV) mode using a low-cost UV-visible spectrophotometer and UV-region derivatization reagents. (JN)

  20. Mixed ionic-electronic conductor-based radiation detectors and methods of fabrication

    DOEpatents

    Conway, Adam; Beck, Patrick R; Graff, Robert T; Nelson, Art; Nikolic, Rebecca J; Payne, Stephen A; Voss, Lars; Kim, Hadong

    2015-04-07

    A method of fabricating a mixed ionic-electronic conductor (e.g. TlBr)-based radiation detector having halide-treated surfaces and associated methods of fabrication, which controls polarization of the mixed ionic-electronic MIEC material to improve stability and operational lifetime.

  1. A Real Valued Neural Network Based Autoregressive Energy Detector for Cognitive Radio Application

    PubMed Central

    Onumanyi, A. J.; Onwuka, E. N.; Aibinu, A. M.; Ugweje, O. C.; Salami, M. J. E.

    2014-01-01

    A real valued neural network (RVNN) based energy detector (ED) is proposed and analyzed for cognitive radio (CR) application. This was developed using a known two-layered RVNN model to estimate the model coefficients of an autoregressive (AR) system. By using appropriate modules and a well-designed detector, the power spectral density (PSD) of the AR system transfer function was estimated and subsequent receiver operating characteristic (ROC) curves of the detector generated and analyzed. A high detection performance with low false alarm rate was observed for varying signal to noise ratio (SNR), sample number, and model order conditions. The proposed RVNN based ED was then compared to the simple periodogram (SP), Welch periodogram (WP), multitaper (MT), Yule-Walker (YW), Burg (BG), and covariance (CV) based ED techniques. The proposed detector showed better performance than the SP, WP, and MT while providing better false alarm performance than the YW, BG, and CV. Data provided here support the effectiveness of the proposed RVNN based ED for CR application. PMID:27379318

  2. Data acquisition system based on fast waveform digitizers for large neutrino detectors

    NASA Astrophysics Data System (ADS)

    Lukyanchenko, G.; Litvinovich, E.

    2016-02-01

    For large volume neutrino and antineutrino detectors it is crucial to have an efficient data acquisition system capable of digitizing data from thousands of detection channels. Here we present a flexible DAQ system architecture consisting of a large number of fast waveform digitizers and configurable FPGA-based trigger logic. The current implementation of the system is functioning in the Borexino neutrino detector providing zero dead time spectroscopy data in the energy range from 1 up to 100 MeV. Acquisition complex in combination with our custom analysis software is successfully being used for registration of geoneutrinos, as well as search for neutrino signal from GRBs, solar netrino spectroscopy and other applications.

  3. Segmented phosphors: MEMS-based high quantum efficiency detectors for megavoltage x-ray imaging.

    PubMed

    Sawant, Amit; Antonuk, Larry E; El-Mohri, Youcef; Li, Yixin; Su, Zhong; Wang, Yi; Yamamoto, Jin; Zhao, Qihua; Du, Hong; Daniel, Jurgen; Street, Robert

    2005-02-01

    Current electronic portal imaging devices (EPIDs) based on active matrix flat panel imager (AMFPI) technology use a metal plate+phosphor screen combination for x-ray conversion. As a result, these devices face a severe trade-off between x-ray quantum efficiency (QE) and spatial resolution, thus, significantly limiting their imaging performance. In this work, we present a novel detector design for indirect detection-based AMFPI EPIDs that aims to circumvent this trade-off. The detectors were developed using micro-electro-mechanical system (MEMS)-based fabrication techniques and consist of a grid of up to approximately 2 mm tall, optically isolated cells of a photoresist material, SU-8. The cells are dimensionally matched to the pixels of the AMFPI array, and packed with a scintillating phosphor. In this paper, various design considerations for such detectors are examined. An empirical evaluation of three small-area (approximately 7 x 7 cm2) prototype detectors is performed in order to study the effects of two design parameters--cell height and phosphor packing density, both of which are important determinants of the imaging performance. Measurements of the x-ray sensitivity, modulation transfer function (MTF) and noise power spectrum (NPS) were performed under radiotherapy conditions (6 MV), and the detective quantum efficiency (DQE) was determined for each prototype SU-8 detector. In addition, theoretical calculations using Monte Carlo simulations were performed to determine the QE of each detector, as well as the inherent spatial resolution due to the spread of absorbed energy. The results of the present studies were compared with corresponding measurements published in an earlier study using a Lanex Fast-B phosphor screen coupled to an indirect detection array of the same design. The SU-8 detectors exhibit up to 3 times higher QE, while achieving spatial resolution comparable or superior to Lanex Fast-B. However, the DQE performance of these early prototypes is

  4. Human emotion detector based on genetic algorithm using lip features

    NASA Astrophysics Data System (ADS)

    Brown, Terrence; Fetanat, Gholamreza; Homaifar, Abdollah; Tsou, Brian; Mendoza-Schrock, Olga

    2010-04-01

    We predicted human emotion using a Genetic Algorithm (GA) based lip feature extractor from facial images to classify all seven universal emotions of fear, happiness, dislike, surprise, anger, sadness and neutrality. First, we isolated the mouth from the input images using special methods, such as Region of Interest (ROI) acquisition, grayscaling, histogram equalization, filtering, and edge detection. Next, the GA determined the optimal or near optimal ellipse parameters that circumvent and separate the mouth into upper and lower lips. The two ellipses then went through fitness calculation and were followed by training using a database of Japanese women's faces expressing all seven emotions. Finally, our proposed algorithm was tested using a published database consisting of emotions from several persons. The final results were then presented in confusion matrices. Our results showed an accuracy that varies from 20% to 60% for each of the seven emotions. The errors were mainly due to inaccuracies in the classification, and also due to the different expressions in the given emotion database. Detailed analysis of these errors pointed to the limitation of detecting emotion based on the lip features alone. Similar work [1] has been done in the literature for emotion detection in only one person, we have successfully extended our GA based solution to include several subjects.

  5. Illuminated push-button switch

    NASA Technical Reports Server (NTRS)

    Iwagiri, T.

    1983-01-01

    An illuminated push-button switch is described. It is characterized by the fact that is consists of a switch group, an operator button opening and closing the switch group, and a light-emitting element which illuminates the face of the operator button.

  6. Examining Signal Decomposition in Ge Tracking Detectors through Source-Based Coincidence Measurements

    NASA Astrophysics Data System (ADS)

    Cromaz, M.; Campbell, C. M.; Clark, R. M.; Crawford, H. L.; Fallon, P.; Lee, I. Y.; Macchiavelli, A. O.; Wiens, A.; Riley, L.; Taniuchi, R.

    2016-03-01

    The performance of a gamma-ray tracking detector, such as those used in the GRETINA spectrometer, is dependent on its ability to accurately locate multiple interaction points in the Ge crystal. Interactions are located by observing both net and induced charge as a function of time on the detector's segmented contact. As multiple interactions are likely, linear combinations of basis signals, a set of simulated signals with unit charge deposited on a grid that spans the detector volume, are fit against the observed signal yielding the interaction positions. While the location of the primary interaction point was found to be good (σpos <= 2 mm) the location of secondary, lower energy interactions appear less reliable. To investigate this issue, we carried out a series of source-based coincidence measurements. These employed a collimated source and a secondary detector by which we could select single interaction events. Given these events originate from known positions, we can take them in combination to directly test the efficacy of the signal decomposition procedure. We will present a description of the method and preliminary results with a GRETINA quad detector. This work is supported by the U.S. Department of Energy under Contract No. DE-AC02-05CHI1231.

  7. Fiber methane gas detector based on harmonic detection and application in ventilation air methane power generation

    NASA Astrophysics Data System (ADS)

    Li, Yanfang; Wei, Yubin; Shang, Ying; Zhao, Yanjie; Zhang, Tingting; Zhao, Weisong; Wang, Chang; Liu, Tongyu

    2010-10-01

    A fiber methane detector based on spectrum absorption is reported. The methane monitor use a distributed feedback diode lasers(DFB) which is near infrared spectroscopy as the optic source, we realized online harmonic detection of the methane. The advantages of this detector include high precision, elimination of interference from humidity and other gases as well as long recalibration cycle. The detection of CH4 is very important in the methane power generation. Especially the detection of the tail gas with high temperature is the dependence to judge the generator. In this paper, we give some data witch gained from the local of methane power generation. The data reach an agreement with the measurements of the sensor using in mine. And the detector has the function of self reference, so the detector is more depended. This proved that the fiber methane detector can meet the needs of the generator. It have some contribution to the production safety of the mine and the energy saving and emission reduction and the environmental protection.

  8. ROOT based Offline and Online Analysis (ROAn): An analysis framework for X-ray detector data

    NASA Astrophysics Data System (ADS)

    Lauf, Thomas; Andritschke, Robert

    2014-10-01

    The ROOT based Offline and Online Analysis (ROAn) framework was developed to perform data analysis on data from Depleted P-channel Field Effect Transistor (DePFET) detectors, a type of active pixel sensors developed at the MPI Halbleiterlabor (HLL). ROAn is highly flexible and extensible, thanks to ROOT's features like run-time type information and reflection. ROAn provides an analysis program which allows to perform configurable step-by-step analysis on arbitrary data, an associated suite of algorithms focused on DePFET data analysis, and a viewer program for displaying and processing online or offline detector data streams. The analysis program encapsulates the applied algorithms in objects called steps which produce analysis results. The dependency between results and thus the order of calculation is resolved automatically by the program. To optimize algorithms for studying detector effects, analysis parameters are often changed. Such changes of input parameters are detected in subsequent analysis runs and only the necessary recalculations are triggered. This saves time and simultaneously keeps the results consistent. The viewer program offers a configurable Graphical User Interface (GUI) and process chain, which allows the user to adapt the program to different tasks such as offline viewing of file data, online monitoring of running detector systems, or performing online data analysis (histogramming, calibration, etc.). Because of its modular design, ROAn can be extended easily, e.g. be adapted to new detector types and analysis processes.

  9. Feasibility of Amorphous Selenium Based Photon Counting Detectors for Digital Breast Tomosynthesis

    SciTech Connect

    Chen, J.; O'Connor, P.; Lehnert, J., De Geronimo, G., Dolazza, E., Tousignant, O., Laperriere, L., Greenspan, J., Zhao, W.

    2009-02-27

    Amorphous selenium (a-Se) has been incorporated successfully in direct conversion flat panel x-ray detectors, and has demonstrated superior image quality in screening mammography and digital breast tomosynthesis (DBT) under energy integration mode. The present work explores the potential of a-Se for photon counting detectors in DBT. We investigated major factors contributing to the variation in the charge collected by a pixel upon absorption of each x-ray photon. These factors included x-ray photon interaction, detector geometry, charge transport, and the pulse shaping and noise properties of the photon counting readout circuit. Experimental measurements were performed on a linear array test structure constructed by evaporating an a-Se layer onto an array of 100 {mu}m pitch strip electrodes, which are connected to a 32 channel low noise photon counting integrated circuit. The measured pulse height spectrum (PHS) under polychromatic xray exposure was interpreted quantitatively using the factors identified. Based on the understanding of a-Se photon counting performance, design parameters were proposed for a 2D detector with high quantum efficiency and count rate that could meet the requirements of photon counting detector for DBT.

  10. 6:1 aspect ratio silicon pillar based thermal neutron detector filled with {sup 10}B

    SciTech Connect

    Nikolic, R. J.; Conway, A. M.; Reinhardt, C. E.; Graff, R. T.; Wang, T. F.; Deo, N.; Cheung, C. L.

    2008-09-29

    Current helium-3 tube based thermal neutron detectors have shortcomings in achieving simultaneously high efficiency and low voltage while maintaining adequate fieldability performance. By using a three-dimensional silicon p-i-n diode pillar array filled with boron-10 these constraints can be overcome. The fabricated pillar structured detector reported here is composed of 2 {mu}m diameter silicon pillars with a 4 {mu}m pitch and height of 12 {mu}m. A thermal neutron detection efficiency of 7.3+/-0.6% and a neutron-to-gamma discrimination of 10{sup 5} at 2 V reverse bias were measured for this detector. When scaled to larger aspect ratio, a high efficiency device is possible.

  11. Detection of fast neutrons using detectors based on semi-insulating GaAs

    NASA Astrophysics Data System (ADS)

    Zat'ko, B.; Sedlačková, K.; Dubecký, F.; Boháček, P.; Sekáčová, M.; Nečas, V.

    2011-12-01

    Detectors with AuZn square Schottky contact of the area of 2.5 × 2.5 mm2 were fabricated. On the back side, the whole area AuGeNi eutectic ohmic contact was evaporated. The thickness of the base material (semi-insulating GaAs) was 220 μm. The connection of 4 detectors in parallel was tested to get the detection area of 25 mm2. The 239Pu-Be fast neutron source with energies between 0.5 and 12 MeV was used in experimental measurements. We have investigated the optimal thickness of HDPE (high-density polyethylene) conversion layer for fast neutron detection. The spectra of the neutrons were measured by detectors covered by HDPE converter of different thicknesses. The fast neutron detection efficiency proved experimentally was compared with results from simulations performed by MCNPX (Monte Carlo N-Particle eXtended) code.

  12. Discriminating cosmic muons and X-rays based on rise time using a GEM detector

    NASA Astrophysics Data System (ADS)

    Wu, Hui-Yin; Zhao, Sheng-Ying; Wang, Xiao-Dong; Zhang, Xian-Ming; Qi, Hui-Rong; Zhang, Wei; Wu, Ke-Yan; Hu, Bi-Tao; Zhang, Yi

    2016-08-01

    Gas electron multiplier (GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade. In this work, a triple GEM device with an effective readout area of 10 cm × 10 cm is developed, and a method of discriminating between cosmic muons and X-rays based on rise time is tested. The energy resolution of the GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. Analysis of the complete signal-cycles allows us to get the rise time and pulse heights. The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold. Supported by National Natural Science Foundation of China (11135002, 11275235, 11405077, 11575073)

  13. A flood map based DOI decoding method for block detector: a GATE simulation study.

    PubMed

    Shi, Han; Du, Dong; Su, Zhihong; Peng, Qiyu

    2014-01-01

    Positron Emission Tomography (PET) systems using detectors with Depth of Interaction (DOI) capabilities could achieve higher spatial resolution and better image quality than those without DOI. Up till now, most DOI methods developed are not cost-efficient for a whole body PET system. In this paper, we present a DOI decoding method based on flood map for low-cost conventional block detector with four-PMT readout. Using this method, the DOI information can be directly extracted from the DOI-related crystal spot deformation in the flood map. GATE simulations are then carried out to validate the method, confirming a DOI sorting accuracy of 85.27%. Therefore, we conclude that this method has the potential to be applied in conventional detectors to achieve a reasonable DOI measurement without dramatically increasing their complexity and cost of an entire PET system. PMID:25227021

  14. Fabrication of Gamma Detectors Based on Magnetic Ag:Er Microcalorimeters

    SciTech Connect

    Friedrich, Stephan; Boyd, Stephen; Cantor, Robin

    2015-11-25

    This report discusses the photolithographic fabrication of ultra-high resolution gamma-ray detectors based on magnetic microcalorimeters (MMCs). The MMC uses a novel Er-doped silver sensor (Ag:Er) that is expected to have higher sensitivity than the Er-doped gold (Au:Er) sensors currently in use. The MMC also integrates the first-stage SQUID preamplifier on the same chip as the MMC gamma detector to increase its signal-to-noise ratio. In addition, the MMC uses a passive Ta-Nb heat switch to replace one of the common long-term failure points in earlier detectors. This report discusses the fabrication process we have developed to implement the proposed improvements.

  15. Heralded linear optical quantum Fredkin gate based on one auxiliary qubit and one single photon detector

    NASA Astrophysics Data System (ADS)

    Zhu, Chang-Hua; Cao, Xin; Quan, Dong-Xiao; Pei, Chang-Xing

    2014-08-01

    Linear optical quantum Fredkin gate can be applied to quantum computing and quantum multi-user communication networks. In the existing linear optical scheme, two single photon detectors (SPDs) are used to herald the success of the quantum Fredkin gate while they have no photon count. But analysis results show that for non-perfect SPD, the lower the detector efficiency, the higher the heralded success rate by this scheme is. We propose an improved linear optical quantum Fredkin gate by designing a new heralding scheme with an auxiliary qubit and only one SPD, in which the higher the detection efficiency of the heralding detector, the higher the success rate of the gate is. The new heralding scheme can also work efficiently under a non-ideal single photon source. Based on this quantum Fredkin gate, large-scale quantum switching networks can be built. As an example, a quantum Beneš network is shown in which only one SPD is used.

  16. Demonstrating a directional detector based on neon for characterizing high energy neutrons

    NASA Astrophysics Data System (ADS)

    Hexley, Allie

    2016-03-01

    MITPC is a gas-based time projection chamber used for detecting fast, MeV-scale neutrons. The standard version of the detector relies on a mixture of 600 torr gas composed of 87.5% helium-4 and 12.5% tetrafluoromethane for precisely measuring the energy and direction of neutron-induced nuclear recoils. I describe studies performed with a prototype detector investigating the use of neon, as a replacement for helium-4, in the gas mixture. My discussion focuses on the advantages of neon as the fast neutron target for high energy neutron events (100 MeV) and a demonstration that the mixture will be effective for this event class. I show that the achievable gain and transverse diffusion of drifting electrons in the neon mixture are acceptable and that the detector uptime lost due to voltage breakdowns in the amplification plane is negligible, compared to 20% with the helium-4 mixture.

  17. Demonstrating a directional detector based on neon for characterizing high energy neutrons

    NASA Astrophysics Data System (ADS)

    Hexley, A.; Moulai, M. H.; Spitz, J.; Conrad, J. M.

    2015-11-01

    MITPC is a gas-based time projection chamber used for detecting fast, MeV-scale neutrons. The standard version of the detector relies on a mixture of 600 torr gas composed of 87.5% 4He and 12.5% CF4 for precisely measuring the energy and direction of neutron-induced nuclear recoils. We describe studies performed with a prototype detector investigating the use of Ne, as a replacement for 4He, in the gas mixture. Our discussion focuses on the advantages of Ne as the fast neutron target for high energy neutron events (lesssim100 MeV) and a demonstration that the mixture will be effective for this event class. We find that the achievable gain and transverse diffusion of drifting electrons in the Ne mixture are acceptable and that the detector uptime lost due to voltage breakdowns in the amplification plane is negligible, compared to ~ 20% with the 4He mixture.

  18. Python based integration of GEM detector electronics with JET data acquisition system

    NASA Astrophysics Data System (ADS)

    Zabołotny, Wojciech M.; Byszuk, Adrian; Chernyshova, Maryna; Cieszewski, Radosław; Czarski, Tomasz; Dalley, Simon; Hogben, Colin; Jakubowska, Katarzyna L.; Kasprowicz, Grzegorz; Poźniak, Krzysztof; Rzadkiewicz, Jacek; Scholz, Marek; Shumack, Amy

    2014-11-01

    This paper presents the system integrating the dedicated measurement and control electronic systems for Gas Electron Multiplier (GEM) detectors with the Control and Data Acquisition system (CODAS) in the JET facility in Culham, England. The presented system performs the high level procedures necessary to calibrate the GEM detector and to protect it against possible malfunctions or dangerous changes in operating conditions. The system also allows control of the GEM detectors from CODAS, setting of their parameters, checking their state, starting the plasma measurement and to reading the results. The system has been implemented using the Python language, using the advanced libraries for implementation of network communication protocols, for object based hardware management and for data processing.

  19. Germanium-Based Detectors for Gamma-Ray Imaging andSpectroscopy

    SciTech Connect

    Amman, Mark; Luke, Paul N.; Boggs, Steven E.

    2006-10-13

    Germanium-based detectors are the standard technology usedfor gamma-ray spectroscopy when high efficiency and excellent energyresolution are desired. By dividing the electrical contacts on thesedetectors into segments, the locations of the gamma-ray interactionevents within the detectors can be determined as well as the depositedenergies. This enables simultaneous gamma-ray imaging and spectroscopyand leads to applications in the areas of astronomy, nuclear physics,environmental remediation, nuclear nonproliferation, and homelandsecurity. Producing the fine-pitched electrode segmentation oftenrequired for imaging has been problematic in the past. To address thisissue, we have developed an amorphous-semiconductor contact technology.Using this technology, fully passivated detectors with closely spacedcontacts can be produced using a simple fabrication process. The currentstate of the amorphous-semiconductor contact technology and thechallenges that remain will be given in this paper.

  20. Nano-optical observation of cascade switching in a parallel superconducting nanowire single photon detector

    SciTech Connect

    Heath, Robert M. Tanner, Michael G.; Casaburi, Alessandro; Hadfield, Robert H.; Webster, Mark G.; San Emeterio Alvarez, Lara; Jiang, Weitao; Barber, Zoe H.; Warburton, Richard J.

    2014-02-10

    The device physics of parallel-wire superconducting nanowire single photon detectors is based on a cascade process. Using nano-optical techniques and a parallel wire device with spatially separate pixels, we explicitly demonstrate the single- and multi-photon triggering regimes. We develop a model for describing efficiency of a detector operating in the arm-trigger regime. We investigate the timing response of the detector when illuminating a single pixel and two pixels. We see a change in the active area of the detector between the two regimes and find the two-pixel trigger regime to have a faster timing response than the one-pixel regime.

  1. Do humans discount the illuminant?

    NASA Astrophysics Data System (ADS)

    McCann, John J.

    2005-03-01

    In constancy experiments, humans report very small changes in appearance with substantial illumination changes. Hermann von Helmholtz introduced the term "discounting the illuminant" to describe 19th century thinking about underlying mechanisms of constancy. It uses an indirect approach. Since observers see objects as constant, observers "must" be able to detect the spatial and spectral changes in illumination and automatically compensate by altering the signals from the quanta catches of retinal receptors. Instead of solving the problem directly by calculating an object"s reflectance from the array of scene radiances, Helmholtz chose to solve the problem of identifying the illumination. Twentieth century experiments by Hubel and Wiesel, Campbell, Land, and Gibson demonstrate the power of mechanisms using spatial comparisons. This paper analyses a series of different experiments looking for unequivocal evidence that either supports "discounting the illuminant" or supports spatial comparisons as the underlying mechanism of constancy.

  2. EIT Based Gas Detector Design by Using Michelson Interferometer

    SciTech Connect

    Abbasian, K.; Rostami, A.; Abdollahi, M. H.

    2011-12-26

    Electromagnetically induced transparency (EIT) is one of the interesting phenomena of light-matter interaction which modifies matter properties for propagation of light. In other words, we can change the absorption and refractive index (RI) in neighborhood of the resonant frequency using EIT. In this paper, we have doped 3-level quantum dots in one of the Michelson Interferometer's mirror and used EIT to change its RI. So, a controllable phase difference between lights in two arms of interferometer is created. Long response time is the main drawback of Michelson interferometer based sensor, which is resolved by this technique.

  3. Diagnosis of pneumothorax using a microwave-based detector

    NASA Astrophysics Data System (ADS)

    Ling, Geoffrey S. F.; Riechers, Ronald G., Sr.; Pasala, Krishna M.; Blanchard, Jeremy; Nozaki, Masako; Ramage, Anthony; Jackson, William; Rosner, Michael; Garcia-Pinto, Patricia; Yun, Catherine; Butler, Nathan; Riechers, Ronald G., Jr.; Williams, Daniel; Zeidman, Seth M.; Rhee, Peter; Ecklund, James M.; Fitzpatrick, Thomas; Lockhart, Stephen

    2001-08-01

    A novel method for identifying pneumothorax is presented. This method is based on a novel device that uses electromagnetic waves in the microwave radio frequency (RF) region and a modified algorithm previously used for the estimation of the angle of arrival of radar signals. In this study, we employ this radio frequency triage tool (RAFT) to the clinical condition of pneumothorax, which is a collapsed lung. In anesthetized pigs, RAFT can detect changes in the RF signature from a lung that is 20 percent or greater collapsed. These results are compared to chest x-ray. Both studies are equivalent in their ability to detect pneumothorax in pigs.

  4. Radioactive threat detection using scintillant-based detectors

    NASA Astrophysics Data System (ADS)

    Chalmers, Alex

    2004-09-01

    An update to the performance of AS&E's Radioactive Threat Detection sensor technology. A model is presented detailing the components of the scintillant-based RTD system employed in AS&E products aimed at detecting radiological WMD. An overview of recent improvements in the sensors, electrical subsystems and software algorithms are presented. The resulting improvements in performance are described and sample results shown from existing systems. Advanced and future capabilities are described with an assessment of their feasibility and their application to Homeland Defense.

  5. Signal processing for a single detector MOEMS based NIR micro spectrometer

    NASA Astrophysics Data System (ADS)

    Heberer, Andreas; Grüger, Heinrich; Zimmer, Fabian; Schenk, Harald; Kenda, Andreas; Frank, Albert; Scherf, Werner

    2005-10-01

    The examination of spectra in the NIR range is necessary for applications like process control, element analysis or medical systems. Typically integrated NIR spectrometers are based on optical setups with diffraction grating and detector arrays. The main disadvantage is price and availability of NIR array InGaAs-based detectors. The implementation of a scanning grating chip realized in a MOEMS technology which integrates the diffractive element makes it possible to detect spectra with single detectors time resolved. Either simple InGaAs photodiodes or cooled detectors may be used. The set up is a shrinked Czerny-Turner spectrometer. The light is coupled in by an optical fibre. After focussing the light passes the scanning grating moving at 150-500 Hz in a sinusoidal way. There it is split off in the different wavelength, the monochrome intensity is caught by a second mirror and led to the detector. The detector signal is amplified by a transimpedance stage and converted to digital with 12 bit resolution. The main part of the signal processing is done by a digital signal processor, which is used to unfold the sinusoidal position and calculate the final spectra. The data rate can be up to 3 MHz, then a spectrum is acquired every 2ms by using a 500Hz Mirror. Using the DSP, the spectrometer can operate autarkic without any PC. Then the spectrum is display on a 160 x 80 pixel graphic LCD. A keypad is used to control the functions. For communication a USB port is included, additional interfaces can be realized by a 16-pin expansion port, which is freely programmable, by the system firmware.

  6. An instrumentation amplifier based readout circuit for a dual element microbolometer infrared detector

    NASA Astrophysics Data System (ADS)

    de Waal, D. J.; Schoeman, J.

    2014-06-01

    The infrared band is widely used in many applications to solve problems stretching over very diverse fields, ranging from medical applications like inflammation detection to military, security and safety applications employing thermal imaging in low light conditions. At the heart of these optoelectrical systems lies a sensor used to detect incident infrared radiation, and in the case of this work our focus is on uncooled microbolometers as thermal detectors. Microbolometer based thermal detectors are limited in sensitivity by various parameters, including the detector layout and design, operating temperature, air pressure and biasing that causes self heating. Traditional microbolometers use the entire membrane surface for a single detector material. This work presents the design of a readout circuit amplifier where a dual detector element microbolometer is used, rather than the traditional single element. The concept to be investigated is based on the principle that both elements will be stimulated with a similar incoming IR signal and experience the same resistive change, thus creating a common mode signal. However, such a common mode signal will be rejected by a differential amplifier, thus one element is placed within a negative resistance converter to create a differential mode signal that is twice the magnitude of the comparable single mode signal of traditional detector designs. An instrumentation amplifier is used for the final stage of the readout amplifier circuit, as it allows for very high common mode rejection with proper trimming of the Wheatstone bridge to compensate for manufacturing tolerance. It was found that by implementing the above, improved sensitivity can be achieved.

  7. Standoff gas leak detectors based on tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Frish, M. B.; Wainner, R. T.; Green, B. D.; Laderer, M. C.; Allen, M. G.

    2005-11-01

    Trace gas sensing and analysis by Tunable Diode Laser Absorption Spectroscopy (TDLAS) has become a robust and reliable technology accepted for industrial process monitoring and control, quality assurance, environmental sensing, plant safety, and infrastructure security. Sensors incorporating well-packaged wavelength-stabilized near-infrared (1.2 to 2.0 μm) laser sources sense over a dozen toxic or industrially-important gases. A large emerging application for TDLAS is standoff sensing of gas leaks, e.g. from natural gas pipelines. The Remote Methane Leak Detector (RMLD), a handheld standoff TDLAS leak survey tool that we developed, is replacing traditional leak detection tools that must be physically immersed within a leak to detect it. Employing a 10 mW 1.6 micron DFB laser, the RMLD illuminates a non-cooperative topographic surface, up to 30 m distant, and analyzes returned scattered light to deduce the presence of excess methane. The eye-safe, battery-powered, 6-pound handheld RMLD enhances walking pipeline survey rates by more than 30%. When combined with a spinning or rastering mirror, the RMLD serves as a platform for mobile leak mapping systems. Also, to enable high-altitude surveying and provide aerial disaster response, we are extending the standoff range to 3000 m by adding an EDFA to the laser transmitter.

  8. Cardiac Multi-detector CT Segmentation Based on Multiscale Directional Edge Detector and 3D Level Set.

    PubMed

    Antunes, Sofia; Esposito, Antonio; Palmisano, Anna; Colantoni, Caterina; Cerutti, Sergio; Rizzo, Giovanna

    2016-05-01

    Extraction of the cardiac surfaces of interest from multi-detector computed tomographic (MDCT) data is a pre-requisite step for cardiac analysis, as well as for image guidance procedures. Most of the existing methods need manual corrections, which is time-consuming. We present a fully automatic segmentation technique for the extraction of the right ventricle, left ventricular endocardium and epicardium from MDCT images. The method consists in a 3D level set surface evolution approach coupled to a new stopping function based on a multiscale directional second derivative Gaussian filter, which is able to stop propagation precisely on the real boundary of the structures of interest. We validated the segmentation method on 18 MDCT volumes from healthy and pathologic subjects using manual segmentation performed by a team of expert radiologists as gold standard. Segmentation errors were assessed for each structure resulting in a surface-to-surface mean error below 0.5 mm and a percentage of surface distance with errors less than 1 mm above 80%. Moreover, in comparison to other segmentation approaches, already proposed in previous work, our method presented an improved accuracy (with surface distance errors less than 1 mm increased of 8-20% for all structures). The obtained results suggest that our approach is accurate and effective for the segmentation of ventricular cavities and myocardium from MDCT images. PMID:26319010

  9. An Adaptive Failure Detector Based on Quality of Service in Peer-to-Peer Networks

    PubMed Central

    Dong, Jian; Ren, Xiao; Zuo, Decheng; Liu, Hongwei

    2014-01-01

    The failure detector is one of the fundamental components that maintain high availability of Peer-to-Peer (P2P) networks. Under different network conditions, the adaptive failure detector based on quality of service (QoS) can achieve the detection time and accuracy required by upper applications with lower detection overhead. In P2P systems, complexity of network and high churn lead to high message loss rate. To reduce the impact on detection accuracy, baseline detection strategy based on retransmission mechanism has been employed widely in many P2P applications; however, Chen's classic adaptive model cannot describe this kind of detection strategy. In order to provide an efficient service of failure detection in P2P systems, this paper establishes a novel QoS evaluation model for the baseline detection strategy. The relationship between the detection period and the QoS is discussed and on this basis, an adaptive failure detector (B-AFD) is proposed, which can meet the quantitative QoS metrics under changing network environment. Meanwhile, it is observed from the experimental analysis that B-AFD achieves better detection accuracy and time with lower detection overhead compared to the traditional baseline strategy and the adaptive detectors based on Chen's model. Moreover, B-AFD has better adaptability to P2P network. PMID:25198005

  10. An adaptive failure detector based on quality of service in peer-to-peer networks.

    PubMed

    Dong, Jian; Ren, Xiao; Zuo, Decheng; Liu, Hongwei

    2014-01-01

    The failure detector is one of the fundamental components that maintain high availability of Peer-to-Peer (P2P) networks. Under different network conditions, the adaptive failure detector based on quality of service (QoS) can achieve the detection time and accuracy required by upper applications with lower detection overhead. In P2P systems, complexity of network and high churn lead to high message loss rate. To reduce the impact on detection accuracy, baseline detection strategy based on retransmission mechanism has been employed widely in many P2P applications; however, Chen's classic adaptive model cannot describe this kind of detection strategy. In order to provide an efficient service of failure detection in P2P systems, this paper establishes a novel QoS evaluation model for the baseline detection strategy. The relationship between the detection period and the QoS is discussed and on this basis, an adaptive failure detector (B-AFD) is proposed, which can meet the quantitative QoS metrics under changing network environment. Meanwhile, it is observed from the experimental analysis that B-AFD achieves better detection accuracy and time with lower detection overhead compared to the traditional baseline strategy and the adaptive detectors based on Chen's model. Moreover, B-AFD has better adaptability to P2P network. PMID:25198005

  11. Gamma thermometer based reactor core liquid level detector

    DOEpatents

    Burns, Thomas J.

    1983-01-01

    A system is provided which employs a modified gamma thermometer for determining the liquid coolant level within a nuclear reactor core. The gamma thermometer which normally is employed to monitor local core heat generation rate (reactor power), is modified by thermocouple junctions and leads to obtain an unambiguous indication of the presence or absence of coolant liquid at the gamma thermometer location. A signal processor generates a signal based on the thermometer surface heat transfer coefficient by comparing the signals from the thermocouples at the thermometer location. The generated signal is a direct indication of loss of coolant due to the change in surface heat transfer when coolant liquid drops below the thermometer location. The loss of coolant indication is independent of reactor power at the thermometer location. Further, the same thermometer may still be used for the normal power monitoring function.

  12. A new GMTI detector based on spaceborne single channel SAR

    NASA Astrophysics Data System (ADS)

    Gao, Fei; Sun, Jinping; Bai, Xia; Yu, Zhenming

    2007-11-01

    This paper examines moving targets detection using single channel Synthetic aperture radar (SAR) in spaceborne platform. Building on previous work moving targets can be retrieved from multi-look images via magnitude subtraction or phase interferometry. A more effective method is proposed which mainly consists of signal subspace processing- based data equilibrium and change detection in multi-look covariance matrix. Also different baseline is checked and weak targets may be found. Test results show that precise calibration of multi-look images are essential and short baseline is preferred when the interesting targets are weak. Therefore, the proposed method leads to improved detection performance and provides ways of GMTI in single channel SAR.

  13. Gamma thermometer based reactor core liquid level detector

    SciTech Connect

    Burns, T.J.

    1983-09-20

    A system is provided which employs a modified gamma thermometer for determining the liquid coolant level within a nuclear reactor core. The gamma thermometer which normally is employed to monitor local core heat generation rate (reactor power), is midified by thermocouple junctions and leads to obtain an unambiguous indication of the presence or absence of coolant liquid at the gamma thermometer location. A signal processor generates a signal based on the thermometer surface heat transfer coefficient by comparing the signals from the thermocouples at the thermometer location. The generated signal is a direct indication of loss of coolant due to the change in surface heat transfer when coolant liquid drops below the thermometer location. The loss of coolant indication is independent of reactor power at the thermometer location. Further, the same thermometer may still be used for the normal power monitoring function.

  14. Bioaerosol collection and concentration for microseparations-based detectors.

    SciTech Connect

    Cummings, Eric B. (Sandia National Laboratories, Livermore, CA); Ellis, C. R. Bowe (Sandia National Laboratories, Livermore, CA); Kanouff, Michael P. (Sandia National Laboratories, Livermore, CA); Rader, Daniel John; Wally, Karl

    2005-03-01

    The ability to detect Weapons of Mass Destruction biological agents rapidly and sensitively is vital to homeland security, spurring development of compact detection systems at Sandia and elsewhere. One such system is Sandia's microseparations-based pChemLab. Many bio-agents are serious health threats even at extremely low concentrations. Therefore, a universal challenge for detection systems is the efficient collection and selective transport of highly diffuse bio-agents against the enormous background of benign particles and species ever present in the ambient environment. We have investigated development of a ''front end'' system for the collection, preconcentration, and selective transport of aerosolized biological agents from dilute (1-10 active particles per liter of air) atmospheric samples, to ultimate concentrations of {approx}20 active particles per microliter of liquid, for interface with microfluidic-based analyses and detection systems. Our approach employs a Sandia-developed aerosol particle-focusing microseparator array to focus size-selected particles into a mating microimpinger array of open microfluidic transport channels. Upon collection (i.e., impingement, submergence, and liquid suspension), microfluidic dielectrophoretic particle concentrators and sorters can be employed to further concentrate and selectively transport bio-agent particles to the sample preparation stages of microfluidic analyses and detection systems. This report documents results in experimental testing, modeling and analysis, component design, and materials fabrication critical to establishing proof-of-principle for this collection ''front end''. Outstanding results have been achieved for the aerodynamic microseparator, and for the post-collection dielectrophoretic concentrator and sorter. Results have been obtained for the microimpinger, too, but issues of particle-trapping by surface tension in liquid surfaces have proven difficult. Subsequent particle submergence into

  15. High-flux ptychographic imaging using the new 55 µm-pixel detector ‘Lambda’ based on the Medipix3 readout chip

    SciTech Connect

    Wilke, R. N. Wallentin, J.; Osterhoff, M.; Pennicard, D.; Zozulya, A.; Sprung, M.; Salditt, T.

    2014-11-01

    The Large Area Medipix-Based Detector Array (Lambda) has been used in a ptychographic imaging experiment on solar-cell nanowires. By using a semi-transparent central stop, the high flux density provided by nano-focusing Kirkpatrick–Baez mirrors can be fully exploited for high-resolution phase reconstructions. Suitable detection systems that are capable of recording high photon count rates with single-photon detection are instrumental for coherent X-ray imaging. The new single-photon-counting pixel detector ‘Lambda’ has been tested in a ptychographic imaging experiment on solar-cell nanowires using Kirkpatrick–Baez-focused 13.8 keV X-rays. Taking advantage of the high count rate of the Lambda and dynamic range expansion by the semi-transparent central stop, a high-dynamic-range diffraction signal covering more than seven orders of magnitude has been recorded, which corresponds to a photon flux density of about 10{sup 5} photons nm{sup −2} s{sup −1} or a flux of ∼10{sup 10} photons s{sup −1} on the sample. By comparison with data taken without the semi-transparent central stop, an increase in resolution by a factor of 3–4 is determined: from about 125 nm to about 38 nm for the nanowire and from about 83 nm to about 21 nm for the illuminating wavefield.

  16. Estimating Ultra-High Energy Cosmic Ray Data as seen from the JEM-EUSO Fluorescence Detector for the planned space based JEM-EUSO detector

    NASA Astrophysics Data System (ADS)

    Fenn, Jeremy; Wiencke, Lawrence

    2014-03-01

    Ultra-high energy cosmic rays (UHECRs) are subatomic particles with energies above 1018 eV. UHECRs are of interest because they are the highest energy particles known to exist. Their source(s), compositions, and the acceleration mechanisms to produce them with energies beyond 1020 eV remain unknown. The Pierre Auger Observatory, located in Argentina, is the world's largest UHECR observatory. It is one of the few a hybrid detectors in the world that combines surface (SD) and fluorescence (FD) detectors. The hybrid detection system is advantageous as it provides a more accurate reconstruction of the incoming cosmic ray's energy and trajectory as it travels through the atmosphere. However, even with the advantage of a hybrid detector, the Pierre Auger has limitations being a ground based observatory. The next generation in UHECR detection is the planned JEM-EUSO mission. The JEM-EUSO mission will consist of a fluorescence detector telescope attached to the International Space Station (ISS). The JEM-EUSO detector is expected to receive an exposure level to UHECRs many times that of the Pierre Auger Observatory by viewing a much larger volume of the atmosphere. In this presentation, I will discuss how data from specific UHECRs collected by the Pierre Auger Observatory is analyzed and altered to estimate what their signatures would look like from space at the planned JEM-EUSO detector. Research advisor

  17. GEM400: A front-end chip based on capacitor-switch array for pixel-based GEM detector

    NASA Astrophysics Data System (ADS)

    Li, H. S.; Jiang, X. S.; Liu, G.; Wang, N.; Sheng, H. Y.; Zhuang, B. A.; Zhao, J. W.

    2012-03-01

    The upgrade of Beijing Synchrotron Radiation Facility (BSRF) needs two-dimensional position-sensitive detection equipment to improve the experimental performance. Gas Electron Multiplier (GEM) detector, in particular, pixel-based GEM detector has good application prospects in the domain of synchrotron radiation. The read-out of larger scale pixel-based GEM detector is difficult for the high density of the pixels (PAD for collecting electrons). In order to reduce the number of cables, this paper presents a read-out scheme for pixel-based GEM detector, which is based on System-in-Package technology and ASIC technology. We proposed a circuit structure based on capacitor switch array circuit, and design a chip GEM400, which is a 400 channels ASIC. The proposed circuit can achieve good stability and low power dissipation. The chip is implemented in a 0.35μm CMOS process. The basic functional circuitry in ths chip includes analog switch, analog buffer, voltage amplifier, bandgap and control logic block, and the layout of this chip takes 5mm × 5mm area. The simulation results show that the chip can allow the maximum amount of input charge 70pC on the condition of 100pF external integrator capacitor. Besides, the chip has good channel uniformity (INL is better than 0.1%) and lower power dissipation.

  18. Edge-on illumination photon-counting for medical imaging

    NASA Astrophysics Data System (ADS)

    Doni, M.; Visser, J.; Koffeman, E.; Herrmann, C.

    2015-08-01

    In medical X-ray Computed Tomography (CT) a silicon based sensor (300-1000 μm) in face-on configuration does not collect the incoming X-rays effectively because of their high energy (40-140 keV). For example, only 2% of the incoming photons at 100 keV are stopped by a 500 μm thick silicon layer. To increase the efficiency, one possibility is to use materials with higher Z (e.g. GaAs, CZT), which have some drawbacks compared to silicon, such as short carrier lifetime or low mobility. Therefore, we investigate whether illuminating silicon edge-on instead of face-on is a solution. Aim of the project is to find and take advantage of the benefits of this new geometry when used for a pixel detector. In particular, we employ a silicon hybrid pixel detector, which is read out by a chip from the Medipix family. Its capabilities to be energy selective will be a notable advantage in energy resolved (spectral) X-ray CT.

  19. LBHNC: A lunar-based heavy nucleus detector

    NASA Astrophysics Data System (ADS)

    Salamon, M. H.; Price, P. B.; Tarlé, G.

    1990-03-01

    A passive, large-area experiment for the detection of cosmic ray actinides on the lunar surface is discussed. Due to the absence of a geomagnetic cutoff, a 100 m2 array of nuclear-track-detecting glass plates in 5 years will detect ~300-1000 U and Th cosmic ray nuclei of energies >~0.85 GeV/u (compared to the present world's total of 4 actinides). With a charge resolution at uranium of ~0.25e, the U/Th ratio can be accurately determined, thereby dating the r-process component of the cosmic rays; the presence of a fresh r-process component would be corroborated by the likely detection of transuranics as well. In addition, abundances in the Pt/Pb and sub-Pt/Pb regions and abundances of secondary actinides would provide detailed data on the 0-1 g/cm2 region of the cosmic ray path length distribution, hence on the astrophysical site of origin of these cosmic rays. Finally, should a fresh r-process component exist, the dection of postulated suerheavy nuclei is conceivable. With an analysis station at the Lunar Base, glass plates could periodically be harvested, analyzed, annealed/remelted, and replaced onto the lunar surface.

  20. An ultrasensitive universal detector based on neutralizer displacement

    NASA Astrophysics Data System (ADS)

    Das, Jagotamoy; Cederquist, Kristin B.; Zaragoza, Alexandre A.; Lee, Paul E.; Sargent, Edward H.; Kelley, Shana O.

    2012-08-01

    Diagnostic technologies that can provide the simultaneous detection of nucleic acids for gene expression, proteins for host response and small molecules for profiling the human metabolome will have a significant advantage in providing comprehensive patient monitoring. Molecular sensors that report changes in the electrostatics of a sensor's surface on analyte binding have shown unprecedented sensitivity in the detection of charged biomolecules, but do not lend themselves to the detection of small molecules, which do not carry significant charge. Here, we introduce the neutralizer displacement assay that allows charge-based sensing to be applied to any class of molecule irrespective of the analyte charge. The neutralizer displacement assay starts with an aptamer probe bound to a neutralizer. When analyte binding occurs the neutralizer is displaced, which results in a dramatic change in the surface charge for all types of analytes. We have tested the sensitivity, speed and specificity of this system in the detection of a panel of molecules: (deoxy)ribonucleic acid, ribonucleic acid, cocaine, adenosine triphosphate and thrombin.

  1. Gamma-ray irradiation effects on InAs/GaSb-based nBn IR detector

    NASA Astrophysics Data System (ADS)

    Cowan, Vincent M.; Morath, Christian P.; Swift, Seth M.; Myers, Stephen; Gautam, Nutan; Krishna, Sanjay

    2011-01-01

    IR detectors operated in a space environment are subjected to a variety of radiation effects while required to have very low noise performance. When properly passivated, conventional mercury cadmium telluride (MCT)-based infrared detectors have been shown to perform well in space environments. However, the inherent manufacturing difficulties associated with the growth of MCT has resulted in a research thrust into alternative detector technologies, specifically type-II Strained Layer Superlattice (SLS) infrared detectors. Theory predicts that SLS-based detector technologies have the potential of offering several advantages over MCT detectors including lower dark currents and higher operating temperatures. Experimentally, however, it has been found that both p-on-n and n-on-p SLS detectors have larger dark current densities than MCT-based detectors. An emerging detector architecture, complementary to SLS-technology and hence forth referred to here as nBn, mitigates this issue via a uni-polar barrier design which effectively blocks majority carrier conduction thereby reducing dark current to more acceptable levels. Little work has been done to characterize nBn IR detectors tolerance to radiation effects. Here, the effects of gamma-ray radiation on an nBn SLS detector are considered. The nBn IR detector under test was grown by solid source molecular beam epitaxy and is composed of an InAs/GaSb SLS absorber (n) and contact (n) and an AlxGa1-xSb barrier (B). The radiation effects on the detector are characterized by dark current density measurements as a function of bias, device perimeter-to-area ratio and total ionizing dose (TID).

  2. Illumination optimization in optical projective lithography

    NASA Astrophysics Data System (ADS)

    Jiang, Hai-bo; Xing, Ting-wen; Du, Meng; Chen, An

    2013-08-01

    As lithography still pushing toward to lower K1 imaging, traditional illumination source shapes may perform marginally in resolving complex layouts, freeform source shapes are expected to achieve better image quality. Illumination optimization as one of inverse lithography techniques attempts to synthesize the input source which leads to the desired output wafer pattern by inverting the forward model from mask to wafer. Usually, inverse lithography problem could be solved by standard numerical methods. Recently, a set of gradient-based numerical methods have been developed to solve the mask optimization problem based on Hopkins' approach. In this study, the same method is also applied to resolve the illumination optimization but based on Abbe imaging formulation for partially coherent illumination. Firstly we state a pixel-based source representation, and analyze the constraint condition for source intensity. Secondly, we propose an objective function which includes three aspects: image fidelity, source smoothness and discretization penalty. Image fidelity is to ensure that the image is as close to the given mask as possible. Source smoothness and discretization penalty are to decrease the source complexity. All of the three items could be described mathematically. Thirdly, we describe the detailed optimization flow, and present the advantages of using Abbe imaging formulation as calculation mode of light intensity. Finally, some simulations were done with initial conventional illumination for 90nm isolated, dense and elbow features separately. As a result, we get irregular dipole source shapes for isolated and dense pattern, and irregular quadrupole for elbow pattern. The results also show that our method could provide great improvements in both image fidelity and source complexity.

  3. Biological Effects Of Artificial Illumination

    NASA Astrophysics Data System (ADS)

    Corth, Richard

    1980-10-01

    We are increasingly being warned of the possible effects of so called "polluted" light, that is light that differs in spectral content from that of sunlight. We should be concerned, we are told, because all animals and plants have evolved under this natural daylight and therefore any difference between that illuminant and the artificial illuminants that are on the market today, is suspect. The usual presentation of the differences between the sunlight and the artificial illuminants are as shown in Figure 1. Here we are shown the spectral power distribution of sunlight and Cool White fluorescent light. The spectral power distributions of each have been normalized to some convenient wavelength so that each can be seen and easily compared on the same figure. But this presentation is misleading for one does not experience artificial illuminants at the same intensity as one experiences sunlight. Sunlight intensities are ordinarily found to be in the 8000 to 10,000 footcandle range whereas artificial illuminants are rarely experienced at intensity levels greater than 100 footcandles. Therefore a representative difference between the two types of illumination conditions is more accurately represented as in Figure 2. Thus if evolutionary adaptations require that humans and other animals be exposed to sunlight to ensure wellbeing, it is clear that one must be exposed to sunlight intensities. It is not feasible to expect that artificially illuminated environments will be lit to the same intensity as sunlight

  4. Transient photocurrent response of three-color detectors based on amorphous silicon

    NASA Astrophysics Data System (ADS)

    Stannowski, B.; Stiebig, H.; Knipp, D.; Wagner, H.

    1999-04-01

    Color detectors based on multilayers of amorphous-silicon alloys facilitate the detection of the three fundamental components of visible light in one single pixel of a sensor array. In order to achieve sensitivity for the blue, green, and red components of light, three different bias voltages are applied to the device. By switching them sequentially the detector is read out. n-i-p-i-i-n structures with a controlled band gap and mobility-lifetime product exhibit excellent stationary properties, namely: good color separation and have dynamic behaviors above 95 dB. Besides the stationary behavior the transient response of a color detector is a further optimization criterion. The experimentally found transient photocurrent response after switching on monochromatic light at different applied bias voltages showed reasonable delay times in the range of tens of milliseconds before reaching steady state. Numerical simulations have been carried out which reproduce this characteristic behavior and facilitate a study of time dependent processes within the device, such as charge transport and storage in localized states. The delay times can be explained by the recharging of electrical defect states in the amorphous material. Consequently, the electrical potential within the device changes, which remarkably affects the carrier transport. Based on these results optimization criteria for the transient behavior of the color detectors are discussed.

  5. GATE simulation of a LYSO-based SPECT imager: Validation and detector optimization

    NASA Astrophysics Data System (ADS)

    Li, Suying; Zhang, Qiushi; Xie, Zhaoheng; Liu, Qi; Xu, Baixuan; Yang, Kun; Li, Changhui; Ren, Qiushi

    2015-02-01

    This paper presents a small animal SPECT system that is based on cerium doped lutetium-yttrium oxyorthosilicate (LYSO) scintillation crystal, position sensitive photomultiplier tubes (PSPMTs) and parallel hole collimator. Spatial resolution test and animal experiment were performed to demonstrate the imaging performance of the detector. Preliminary results indicated a spatial resolution of 2.5 mm at FWHM that cannot meet our design requirement. Therefore, we simulated this gamma camera using GATE (GEANT 4 Application for Tomographic Emission) aiming to make detector spatial resolution less than 2 mm. First, the GATE simulation process was validated through comparison between simulated and experimental data. This also indicates the accuracy and effectiveness of GATE simulation for LYSO-based gamma camera. Then the different detector sampling methods (crystal size with 1.5, and 1 mm) and collimator design (collimator height with 30, 34.8, 38, and 43 mm) were studied to figure out an optimized parameter set. Detector sensitivity changes were also focused on with different parameters set that generated different spatial resolution results. Tradeoff curves of spatial resolution and sensitivity were plotted to determine the optimal collimator height with different sampling methods. Simulation results show that scintillation crystal size of 1 mm and collimator height of 38 mm, which can generate a spatial resolution of ~1.8 mm and sensitivity of ~0.065 cps/kBq, can be an ideal configuration for our SPECT imager design.

  6. Integrated USB based readout interface for silicon strip detectors of the ATLAS SCT module

    NASA Astrophysics Data System (ADS)

    Masek, P.; Linhart, V.; Granja, C.; Pospisil, S.; Husak, M.

    2011-12-01

    An integrated portable USB based readout interface for the ATLAS semiconductor trackers (SCT) has been built. The ATLAS SCT modules are large area silicon strip detectors designed for tracking of high-energy charged particles resulting in collisions on Large Hadron Collider (LHC) in CERN. These modules can be also used on small accelerators for medical or industry applications where a compact and configurable readout interface would be useful. A complete custom made PC-host software tool was written for Windows platform for control and DAQ with build-in online visualization. The new constructed interface provides integrated power, control and DAQ and configurable communication between the detector module and the controlling PC. The interface is based on the Field Programmable Gate Array (FPGA) and the high speed USB 2.0 standard. This design permits to operate the modules under high particle fluence while minimizing the dead time of the whole detection system. Utilization of the programmable device simplifies the operation and permits future expansion of the functionality without any hardware changes. The device includes the high voltage source for detector bias up to 500 V and it is equipped with number of devices for monitoring the operation and conditions of measurement (temperature, humidity, voltage). These features are particularly useful as the strip detector must be operated in a well controlled environment. The operation of the interface will be demonstrated on data measured with different particles from radiation sources.

  7. A Wireless Sensor Network-Based Portable Vehicle Detector Evaluation System

    PubMed Central

    Yoo, Seong-eun

    2013-01-01

    In an upcoming smart transportation environment, performance evaluations of existing Vehicle Detection Systems are crucial to maintain their accuracy. The existing evaluation method for Vehicle Detection Systems is based on a wired Vehicle Detection System reference and a video recorder, which must be operated and analyzed by capable traffic experts. However, this conventional evaluation system has many disadvantages. It is inconvenient to deploy, the evaluation takes a long time, and it lacks scalability and objectivity. To improve the evaluation procedure, this paper proposes a Portable Vehicle Detector Evaluation System based on wireless sensor networks. We describe both the architecture and design of a Vehicle Detector Evaluation System and the implementation results, focusing on the wireless sensor networks and methods for traffic information measurement. With the help of wireless sensor networks and automated analysis, our Vehicle Detector Evaluation System can evaluate a Vehicle Detection System conveniently and objectively. The extensive evaluations of our Vehicle Detector Evaluation System show that it can measure the traffic information such as volume counts and speed with over 98% accuracy. PMID:23344388

  8. Studying radiation hardness of a cadmium tungstate crystal based radiation detector

    NASA Astrophysics Data System (ADS)

    Shtein, M. M.; Smekalin, L. F.; Stepanov, S. A.; Zatonov, I. A.; Tkacheva, T. V.; Usachev, E. Yu

    2016-06-01

    The given article considers radiation hardness of an X-ray detector used in production of non-destructive testing instruments and inspection systems. In the course of research, experiments were carried out to estimate radiation hardness of a detector based on cadmium tungstate crystal and its structural components individually. The article describes a layout of an experimental facility that was used for measurements of radiation hardness. The radiation dose dependence of the photodiode current is presented, when it is excited by a light flux of a scintillator or by an external light source. Experiments were carried out to estimate radiation hardness of two types of optical glue used in detector production; they are based on silicon rubber and epoxy. With the help of a spectrophotometer and cobalt gun, each of the glue samples was measured for a relative light transmission factor with different wavelengths, depending on the radiation dose. The obtained data are presented in a comprehensive analysis of the results. It was determined, which of the glue samples is most suitable for production of detectors working under exposure to strong radiation.

  9. Radon monitoring using long-range alpha detector-based technology

    SciTech Connect

    Bolton, R.D.

    1994-11-01

    Long-Range Alpha Detector (LRAD) technology is being studied for monitoring radon gas concentrations. LRAD-based instruments collect and measure the ionization produced in air by alpha decays. These ions can be moved to a collection grid via electrostatic ion-transport design collected approximately 95% of the radon produced ions, while instruments using an airflow transport design collected from 44% to 77% of these ions, depending on detector geometry. The current produced by collecting this ionization is linear with respect to {sup 222}Rn concentration over the available test range of 0.07 to 820 pCi/L. In the absence of statistical limitations due to low radon concentrations, the speed of response of LRAD-based instruments is determined by the air exchange rate, and therefore changes in radon concentration can be detected in just a few seconds. Recent tests show that at radon concentrations below 20 pCi/L current pulses produced by individual alpha decays can be counted, thus improving detector sensitivity and stability even further. Because these detectors are simple, rugged, and do not consume much power, they are natural candidates for portable, battery operation.

  10. Geometric optimization of a neutron detector based on a lithium glass-polymer composite

    NASA Astrophysics Data System (ADS)

    Mayer, M.; Nattress, J.; Trivelpiece, C.; Jovanovic, I.

    2015-06-01

    We report on the simulation and optimization of a neutron detector based on a glass-polymer composite that achieves high gamma rejection. Lithium glass is embedded in polyvinyltoluene in three geometric forms: disks, rods, and spheres. Optimal shape, geometric configuration, and size of the lithium glass fragments are determined using Geant4 simulations. All geometrical configurations maintain an approximate 7% glass to polymer mass ratio. Results indicate a 125-mm diameter as the optimal detector size for initial prototype design achieving a 10% efficiency for the thermalization of incident fission neutrons from 252Cf. The geometrical features of a composite detector are shown to have little effect on the intrinsic neutron efficiency, but a significant effect on the gamma rejection is observed. The sphere geometry showed the best overall performance with an intrinsic neutron efficiency of approximately 6% with a gamma rejection better than 10-7 for 280-μm diameter spheres. These promising results provide a motivation for prototype composite detector development based on the simulated designs.

  11. Measurement of image plane illumination uniformity of photoelectric imaging system

    NASA Astrophysics Data System (ADS)

    Kang, Deng-kui; Yang, Hong; Sha, Ding-guo; Jiang, Chang-lu; Chen, Min; Zhong, Xing-hui; Ma, Shi-bang; Yuan, Liang

    2014-09-01

    The image plane illumination nonuniformity caused by optical system or detector will affect the detection precision of photoelectric imaging system, especially in image guidance, positioning and recognition. An image plane illumination uniformity measurement device was set up, which was characteristiced of high uniformity and wide dynamic range. The device was composed of an asymmetric integrating sphere,the image collection and processing system, as well as the electrical control system.The asymmetric integrating sphere had two different radius,which was respectively 800mm and 1000mm.The spectral region was (0.4~1.1)μm, the illumination range was (1×10-4~2×104)lx. The image collection and processing system had two different acquisition card,which were respectively used for analog and digital signals. The software can process for dynamic image or static image. The TracePro software was used to make a internal ray tracing of integrating sphere, the illumination uniformity at the export was simulated for the size of 330mm×230mm and Φ 100mm export, the results were respectively 97.95% and 98.33%. Then,an illuminometer was used to measure the actual illumination uniformity of integrating sphere, the result was shown the actual illumination uniformity was 98.8%. Finally, a visible photoelectric imaging system was tested ,and three different uniformity indicators results were given.

  12. Low SWaP MWIR detector based on XBn focal plane array

    NASA Astrophysics Data System (ADS)

    Klipstein, P. C.; Gross, Y.; Aronov, D.; ben Ezra, M.; Berkowicz, E.; Cohen, Y.; Fraenkel, R.; Glozman, A.; Grossman, S.; Klin, O.; Lukomsky, I.; Marlowitz, T.; Shkedy, L.; Shtrichman, I.; Snapi, N.; Tuito, A.; Yassen, M.; Weiss, E.

    2013-06-01

    Over the past few years, a new type of High Operating Temperature (HOT) photon detector has been developed at SCD, which operates in the blue part of the MWIR window of the atmosphere (3.4-4.2 μm). This window is generally more transparent than the red part of the MWIR window (4.4-4.9 μm), especially for mid and long range applications. The detector has an InAsSb active layer, and is based on the new "XBn" device concept. We have analyzed various electrooptical systems at different atmospheric temperatures, based on XBn-InAsSb operating at 150K and epi-InSb at 95K, respectively, and find that the typical recognition ranges of both detector technologies are similar. Therefore, for very many applications there is no disadvantage to using XBn-InAsSb instead of InSb. On the other hand XBn technology confers many advantages, particularly in low Size, Weight and Power (SWaP) and in the high reliability of the cooler and Integrated Detector Cooler Assembly (IDCA). In this work we present a new IDCA, designed for 150K operation. The 15 μm pitch 640×512 digital FPA is housed in a robust, light-weight, miniaturised Dewar, attached to Ricor's K562S Stirling cycle cooler. The complete IDCA has a diameter of 28 mm, length of 80 mm and weight of < 300 gm. The total IDCA power consumption is ~ 3W at a 60Hz frame rate, including an external miniature proximity card attached to the outside of the Dewar. We describe some of the key performance parameters of the new detector, including its NETD, RNU and operability, pixel cross-talk, and early stage yield results from our production line.

  13. Recent progress in InSb based quantum detectors in Israel

    NASA Astrophysics Data System (ADS)

    Klipstein, Philip; Aronov, Daniel; Ezra, Michael ben; Barkai, Itzik; Berkowicz, Eyal; Brumer, Maya; Fraenkel, Rami; Glozman, Alex; Grossman, Steve; Jacobsohn, Eli; Klin, Olga; Lukomsky, Inna; Shkedy, Lior; Shtrichman, Itay; Snapi, Noam; Yassen, Michael; Weiss, Eliezer

    2013-07-01

    InSb is a III-V binary semiconductor material with a bandgap wavelength of 5.4 μm at 77 K, well matched to the 3-5 μm MWIR atmospheric transmission window. When configured as a Focal Plane Array (FPA) detector, InSb photodiodes offer a large quantum efficiency, combined with excellent uniformity and high pixel operability. As such, InSb arrays exhibit good scalability and are an excellent choice for large format FPAs at a reasonable cost. The dark current is caused by Generation-Recombination (G-R) centres in the diode depletion region, and this leads to a typical operating temperature of ˜80 K in detectors with a planar implanted p-n junction. Over the last 15 years SCD has developed and manufactured a number of different 2-dimensional planar FPA formats, with pitches in the range of 15-30 μm. In recent years a new epi-InSb technology has been developed at SCD, in which the G-R contribution to the dark current is reduced. This enables InSb detector operation at 95-100 K, with equivalent performance to standard InSb at 80 K. In addition, using a new patented XBnn device architecture in which the G-R current is totally suppressed, epitaxial InAsSb detectors have been developed with a bandgap wavelength of 4.2 μm, which can operate in the 150-170 K range. In this short review of the past two decades, a number of key achievements in SCD's InSb based detector development program are described. These include High Operating Temperature (HOT) epi-InSb FPAs, large format megapixel FPAs with high functionality using a digital Read Out Integrated Circuit (ROIC), and ultra low Size, Weight and Power (SWaP) FPAs based on the HOT XBnn architecture.

  14. Efficient Illumination for Microsecond Tracking Microscopy

    PubMed Central

    Dulin, David; Barland, Stephane; Hachair, Xavier; Pedaci, Francesco

    2014-01-01

    The possibility to observe microsecond dynamics at the sub-micron scale, opened by recent technological advances in fast camera sensors, will affect many biophysical studies based on particle tracking in optical microscopy. A main limiting factor for further development of fast video microscopy remains the illumination of the sample, which must deliver sufficient light to the camera to allow microsecond exposure times. Here we systematically compare the main illumination systems employed in holographic tracking microscopy, and we show that a superluminescent diode and a modulated laser diode perform the best in terms of image quality and acquisition speed, respectively. In particular, we show that the simple and inexpensive laser illumination enables less than s camera exposure time at high magnification on a large field of view without coherence image artifacts, together with a good hologram quality that allows nm-tracking of microscopic beads to be performed. This comparison of sources can guide in choosing the most efficient illumination system with respect to the specific application. PMID:25251462

  15. A Quantitative Measure of Field Illumination.

    PubMed

    Brown, Claire M; Reilly, Andrew; Cole, Richard W

    2015-07-01

    In this paper, we describe a statistically based algorithm to quantify the uniformity of illumination in an optical light microscopy imaging system that outputs a single quality factor (QF) score. The importance of homogeneous field illumination in quantitative light microscopy is well understood and often checked. However, there is currently no standard automatic quantitative measure of the uniformity of the field illumination. Images from 89 different laser-scanning confocal microscopes (LSCMs), which were collected as part of an international study on microscope quality assessment, were used as a "training" set to build the algorithm. To validate the algorithm and verify its robustness, images from 33 additional microscopes, including LSCM and wide-field (WF) microscopes, were used. The statistical paradigm used for developing the quality scoring scale was a regression approach to supervised learning. Three intensity profiles across each image-2 corner-to-corner diagonals and a center horizontal-were used to generate pixel-intensity data. All of the lines passed through the center of the image. The intensity profile data then were converted into a single-field illumination QF score in the range of 0-100, with 0 having extreme variation, and therefore, essentially unusable, and 100 having no deviation, i.e., straight lines with a constant uniform intensity. Empirically, a QF ≥ 83 was determined to be the minimum acceptable value based on manufacturer acceptance tests and reasonably achievable values. This new QF is an invaluable metric to ascertain objectively and easily the uniformity of illumination quality, provide a traceable reference for monitoring field uniformity over time, and make a direct comparison among different microscopes. The QF can also be used as an indicator of system failure and the need for alignment or service of the instrument. PMID:25802488

  16. A Quantitative Measure of Field Illumination

    PubMed Central

    Brown, Claire M.; Reilly, Andrew

    2015-01-01

    In this paper, we describe a statistically based algorithm to quantify the uniformity of illumination in an optical light microscopy imaging system that outputs a single quality factor (QF) score. The importance of homogeneous field illumination in quantitative light microscopy is well understood and often checked. However, there is currently no standard automatic quantitative measure of the uniformity of the field illumination. Images from 89 different laser-scanning confocal microscopes (LSCMs), which were collected as part of an international study on microscope quality assessment, were used as a “training” set to build the algorithm. To validate the algorithm and verify its robustness, images from 33 additional microscopes, including LSCM and wide-field (WF) microscopes, were used. The statistical paradigm used for developing the quality scoring scale was a regression approach to supervised learning. Three intensity profiles across each image—2 corner-to-corner diagonals and a center horizontal—were used to generate pixel-intensity data. All of the lines passed through the center of the image. The intensity profile data then were converted into a single-field illumination QF score in the range of 0–100, with 0 having extreme variation, and therefore, essentially unusable, and 100 having no deviation, i.e., straight lines with a constant uniform intensity. Empirically, a QF ≥ 83 was determined to be the minimum acceptable value based on manufacturer acceptance tests and reasonably achievable values. This new QF is an invaluable metric to ascertain objectively and easily the uniformity of illumination quality, provide a traceable reference for monitoring field uniformity over time, and make a direct comparison among different microscopes. The QF can also be used as an indicator of system failure and the need for alignment or service of the instrument. PMID:25802488

  17. Hourly Illumination of Shackleton Crater

    NASA Video Gallery

    Illumination of Shackleton crater, a 21-km-diameter (12.5 mile-diameter) structure situated adjacent to the Moon’s south pole. The resolution is 30 meters (approximately 100 feet) per pixel. Fra...

  18. Laser sources for object illumination

    SciTech Connect

    Albrecht, G.F.

    1994-11-15

    The considerations which formulate the specifications for a laser illuminator are explained, using the example of an underwater object. Depending on the parameters which define the scenario, widely varying laser requirements result.

  19. Recent developments in a CdTe-based x-ray detector for digital radiography

    NASA Astrophysics Data System (ADS)

    Glasser, Francis; Martin, Jean-Luc; Thevenin, Bernard; Schermesser, Patrick; Pantigny, Philippe; Laurent, Jean Yves; Rambaud, Philippe; Pitault, Bernard; Paltrier, Sylvain

    1997-05-01

    The performance of a new CdTe based x-ray detector devoted to digital radiography are presented. The detectors consist of a 6 cm2 CdTe 2D-array connected to CMOS readout circuit by indium bumps. The final image has 400 X 600 pixels with a 50 micron pitch. This solid-state detector presents the advantages of direct conversion, i.e. high stopping power with high spatial resolution and a significantly higher signal than commercially available scintillator/photodetector systems. The experimental results show excellent linearity, spatial resolution and detective quantum efficiency. The MTF was measured by the angled-slit method: 20 to 30 percent at 10 1p/mm depending on the incident x-ray energy. The measured DQE is about 0.8 at 40 KeV and 100 (mu) Gray dose. Our simulation shows that these experimental results do not reach the theoretical limit. Further improvements are in progress. The first industrial application will be dental radiography due to the small size and the excellent performances. We also tested the detector with x-rays form 20 KeV to 1.25 MeV. Of course the CdTe thickness should then be adapted to the incident x-ray energy.

  20. Ultracold neutron detectors based on 10B converters used in the qBounce experiments☆

    PubMed Central

    Jenke, Tobias; Cronenberg, Gunther; Filter, Hanno; Geltenbort, Peter; Klein, Martin; Lauer, Thorsten; Mitsch, Kevin; Saul, Heiko; Seiler, Dominik; Stadler, David; Thalhammer, Martin; Abele, Hartmut

    2013-01-01

    Gravity experiments with very slow, so-called ultracold neutrons connect quantum mechanics with tests of Newton's inverse square law at short distances. These experiments face a low count rate and hence need highly optimized detector concepts. In the frame of this paper, we present low-background ultracold neutron counters and track detectors with micron resolution based on a 10B converter. We discuss the optimization of 10B converter layers, detector design and concepts for read-out electronics focusing on high-efficiency and low-background. We describe modifications of the counters that allow one to detect ultracold neutrons selectively on their spin-orientation. This is required for searches of hypothetical forces with spin–mass couplings. The mentioned experiments utilize a beam-monitoring concept which accounts for variations in the neutron flux that are typical for nuclear research facilities. The converter can also be used for detectors, which feature high efficiencies paired with high spatial resolution of 1–2μm. They allow one to resolve the quantum mechanical wave function of an ultracold neutron bound in the gravity potential above a neutron mirror. PMID:25843998

  1. Cooled and uncooled infrared detectors based on yttrium barium copper oxide

    NASA Astrophysics Data System (ADS)

    Sobolewski, Roman; Butler, Donald P.; Celik-Butler, Zeynep

    2001-03-01

    We review performance and physical characteristics of yttrium barium copper oxide (YBCO) compound as an infrared (IR) photodetector. YBCO has been used as the IR detector material in both superconducting (oxygen-rich) and semiconducting (oxygen-depleted) phases. YBCO in its crystalline, Yba2Cu3O6+x phase with x>0.95 is a high-temperature superconducting material with the superconducting transition Tcapproximately equals 90K. The superconducting YBCOIR detectors operate as either nonequilibrium (quantum) or bolometric (thermal) devices. The nonequilibrium devices are characterized by very short, single-picosecond photoresponse times and are expected to find applications in optoelectronics and imaging, as well as ultrafast optical-to-electrical transducers for digital input applications. The bolometric mechanism results in relatively slow but very sensitive detectors with possible applications in astronomy. In addition to superconducting IR sensors, interest in uncooled YBCO devices is growing very rapidly. Despite somewhat lower sensitivity and significantly reduced speed of response, as compared to the superconducting counterpartners, the uncooled IR detectors are characterized by much lower operating cost and weight due to lack of cooling cryogens and are compatible with existing silicon-based processing and fabrication. The last point is of paramount importance if the IR-sensitive pixels are to be integrated with CMOS read-out circuitry for monolithic focal plane arrays and infrared cameras. Amorphous uncooled YBCO photodetectors operate as either photoconductive bolometers of unbiased pyroelectric devices.

  2. Study on the technology of mutual alignment based on the four-quadrant photo electric detector

    NASA Astrophysics Data System (ADS)

    Hu, Ya-bin; Wang, Miao

    2015-11-01

    Panoramic stereo cameras and laser radars have their own coordinate system in the dynamic spatial sensing area and they have to determine the position relationship between each other through joint calibration. As using the traditional technology of mutual alignment based on the telescope cross wire is tedious and requires high operating skills, a new method of mutual alignment using lasers and four-quadrant photo electric detectors is provided after analyzing the working principle of four-quadrant photo electric detectors. Firstly make the laser beam irradiate the active area of the four-quadrant photo electric detector through coarse aiming. Then the center of a light spot offset relative to the center of the active area can be obtained according to the output voltage of four quadrants. The pose of two instruments can be adjusted properly to realize mutual alignment. The experimental results indicate that the alignment accuracy of four-quadrant detectors can meet the requirements of mutual alignment, which provides a new idea for joint calibration.

  3. A spectroscopy-based detector to monitor tomato growth condition in greenhouse

    NASA Astrophysics Data System (ADS)

    Yang, Ce; Li, Minzan; Cui, Di

    2008-12-01

    A spectroscopy-based detector is developed to measure the nitrogen and chlorophyll content of tomato leaves and then to predict the growth condition of tomato plants in greenhouse. The detector uses two wavebands, 527 nm and 762 nm, since it is proved that these wavebands are sensitive to nitrogen and chlorophyll content in plant leaves by previous field test. The detector contains: A Y-type optic fiber, two silicon photocells, a signal processing unit, and a MCU. Light reflection from tomato leaves is transmitted by the Y-type optic fiber to the surface of the silicon photo cells, which transfer optical signal into electrical signal. Then the analog signal is amplified to conform to the TTL level signal standard and finally converted to digital signal by MAX186. After that, the MCU carries on a series of actions, including data calculating, displaying and storage. Using the measured data, the Normalized Difference Vegetation Index (NDVI) is calculated to estimate the nitrogen and chlorophyll content in plant leaves. The result is directly displayed on an LCD screen. Users have an option in saving data, either into a USB-memory stick or into a database over the PC serial port. The detector is portable, inexpensive, and convenient, which make it meet farmers' need in China. The performance test shows that the growth model works very well, and the device has high accuracy in predicting the growth condition of tomato plants in greenhouse.

  4. A Novel Temperature Monitoring Sensor for Gas-Based Detectors in Large HEP Experiments

    NASA Astrophysics Data System (ADS)

    Benussi, L.; Bianco, S.; Caponero, M. A.; Colafranceschi, S.; Ferrini, M.; Felli, F.; Passamonti, L.; Pierluigi, D.; Polimadei, A.; Russo, A.; Saviano, G.; Vendittozzi, C.

    Gaseous detectors are commonly used in HEP (High Energy Physics) experiments to reconstruct the track of elementary particles. They are often made by a very large number of chambers with relatively small individual volume, arranged in thick layers placed approximately all around the vertex of the experiment in order to detect elementary particles produced in any direction. The large volume of gas inside the detector must be monitored for many parameters as they can affect both the efficiency and the working life of the detector. The temperature of the gas inside the individual chambers is a critical parameter to be monitored, as it can both affect the efficiency of the detector and point out on-board electronic circuitry overheating. In this paper we propose a novel gas temperature sensing system based on optical fibre technology. The adopted technology is well suited to make distributed sensing systems with large number of sensors, it is immune to electromagnetic disturbances and it has adequate radiation hardness. A prototype of the basic sensor of the proposed system was tested at the experimental facility for Resistive Plate Chamber characterization available at the INFN laboratories in Frascati. Results are presented and discussed.

  5. Research on infrared-image denoising algorithm based on the noise analysis of the detector

    NASA Astrophysics Data System (ADS)

    Liu, Songtao; Zhou, Xiaodong; Shen, Tongsheng; Han, Yanli

    2005-01-01

    Since the conventional denoising algorithms have not considered the influence of certain concrete detector, they are not very effective to remove various noises contained in the low signal-to-noise ration infrared image. In this paper, a new thinking for infrared image denoising is proposed, which is based on the noise analyses of detector with an example of L model infrared multi-element detector. According to the noise analyses of this detector, the emphasis is placed on how to filter white noise and fractal noise in the preprocessing phase. Wavelet analysis is a good tool for analyzing 1/f process. 1/f process can be viewed as white noise approximately since its wavelet coefficients are stationary and uncorrelated. So if wavelet transform is adopted, the problem of removing white noise and fraction noise is simplified as the only one problem, i.e., removing white noise. To address this problem, a new wavelet domain adaptive wiener filtering algorithm is presented. From the viewpoint of quantitative and qualitative analyses, the filtering effect of our method is compared with those of traditional median filter, mean filter and wavelet thresholding algorithm in detail. The results show that our method can reduce various noises effectively and raise the ratio of signal-to-noise evidently.

  6. An HEMT-Based Cryogenic Charge Amplifier for Sub-kelvin Semiconductor Radiation Detectors

    NASA Astrophysics Data System (ADS)

    Phipps, A.; Sadoulet, B.; Juillard, A.; Jin, Y.

    2016-07-01

    We present the design and noise performance of a fully cryogenic (T=4 K) high-electron mobility transistor (HEMT)-based charge amplifier for readout of sub-kelvin semiconductor radiation detectors. The amplifier is being developed for use in direct detection dark matter searches such as the cryogenic dark matter search and will allow these experiments to probe weakly interacting massive particle masses below 10 GeV/c^2 while retaining background discrimination. The amplifier dissipates ≈ 1 mW of power and provides an open loop voltage gain of several hundreds. The measured noise performance is better than that of JFET-based charge amplifiers and is dominated by the noise of the input HEMT. An optimal filter calculation using the measured closed loop noise and typical detector characteristics predicts a charge resolution of σ _q=106 eV (35 electrons) for leakage currents below 4 × 10^{-15} A.

  7. A Review of Accelerometry-Based Wearable Motion Detectors for Physical Activity Monitoring

    PubMed Central

    Yang, Che-Chang; Hsu, Yeh-Liang

    2010-01-01

    Characteristics of physical activity are indicative of one’s mobility level, latent chronic diseases and aging process. Accelerometers have been widely accepted as useful and practical sensors for wearable devices to measure and assess physical activity. This paper reviews the development of wearable accelerometry-based motion detectors. The principle of accelerometry measurement, sensor properties and sensor placements are first introduced. Various research using accelerometry-based wearable motion detectors for physical activity monitoring and assessment, including posture and movement classification, estimation of energy expenditure, fall detection and balance control evaluation, are also reviewed. Finally this paper reviews and compares existing commercial products to provide a comprehensive outlook of current development status and possible emerging technologies. PMID:22163626

  8. Binary complementary white LED illumination

    NASA Astrophysics Data System (ADS)

    Roberts, John K.

    2001-12-01

    For widespread adoption in general-purpose illumination applications, light-emitting diodes (LEDs) must reliably produce a substantial amount of white light at a reasonable cost. While several white LED technologies appear capable of meeting the implicit technical requirements for illumination, their high purchase price (relative to traditional light sources) has heretofore impeded their market advancement. Binary complementary white (BCW) LED illuminators, first introduced commercially in late 1997, appear to offer great potential for addressing the commercial and technical demands of general-purpose illumination applications. Many properties of BCW LED systems derive from AlInGaP LED chips, the source of up to 80% of the luminous flux projected from BCW devices. This configuration yields a number of benefits, relative to other white LED approaches, including high luminous efficacy, low cost per lumen, and high luminous flux per discrete component. This document describes BCW illumination systems in detail, beginning with a review of generic LED attributes, basic illumination requirements and applied photometric and colorimetric techniques.

  9. Fluence-based dosimetry of proton and heavier ion beams using single track detectors

    NASA Astrophysics Data System (ADS)

    Klimpki, G.; Mescher, H.; Akselrod, M. S.; Jäkel, O.; Greilich, S.

    2016-02-01

    Due to their superior spatial resolution, small and biocompatible fluorescent nuclear track detectors (FNTDs) open up the possibility of characterizing swift heavy charged particle fields on a single track level. Permanently stored spectroscopic information such as energy deposition and particle field composition is of particular importance in heavy ion radiotherapy, since radiation quality is one of the decisive predictors for clinical outcome. Findings presented within this paper aim towards single track reconstruction and fluence-based dosimetry of proton and heavier ion fields. Three-dimensional information on individual ion trajectories through the detector volume is obtained using fully automated image processing software. Angular distributions of multidirectional fields can be measured accurately within  ±2° uncertainty. This translates into less than 5% overall fluence deviation from the chosen irradiation reference. The combination of single ion tracking with an improved energy loss calibration curve based on 90 FNTD irradiations with protons as well as helium, carbon and oxygen ions enables spectroscopic analysis of a detector irradiated in Bragg peak proximity of a 270 MeV u-1 carbon ion field. Fluence-based dosimetry results agree with treatment planning software reference.

  10. Fluence-based dosimetry of proton and heavier ion beams using single track detectors.

    PubMed

    Klimpki, G; Mescher, H; Akselrod, M S; Jäkel, O; Greilich, S

    2016-02-01

    Due to their superior spatial resolution, small and biocompatible fluorescent nuclear track detectors (FNTDs) open up the possibility of characterizing swift heavy charged particle fields on a single track level. Permanently stored spectroscopic information such as energy deposition and particle field composition is of particular importance in heavy ion radiotherapy, since radiation quality is one of the decisive predictors for clinical outcome. Findings presented within this paper aim towards single track reconstruction and fluence-based dosimetry of proton and heavier ion fields. Three-dimensional information on individual ion trajectories through the detector volume is obtained using fully automated image processing software. Angular distributions of multidirectional fields can be measured accurately within  ±2° uncertainty. This translates into less than 5% overall fluence deviation from the chosen irradiation reference. The combination of single ion tracking with an improved energy loss calibration curve based on 90 FNTD irradiations with protons as well as helium, carbon and oxygen ions enables spectroscopic analysis of a detector irradiated in Bragg peak proximity of a 270 MeV u(-1) carbon ion field. Fluence-based dosimetry results agree with treatment planning software reference. PMID:26757791

  11. Development of Ta-based Superconducting Tunnel Junction X-ray Detectors for Fluorescence XAS

    SciTech Connect

    Friedrich, S; Drury, O; Hall, J; Cantor, R

    2009-09-23

    We are developing superconducting tunnel junction (STJ) soft X-ray detectors for chemical analysis of dilute samples by fluorescence-detected X-ray absorption spectroscopy (XAS). Our 36-pixel Nb-based STJ spectrometer covers a solid angle {Omega}/4{pi} {approx} 10{sup -3}, offers an energy resolution of {approx}10-20 eV FWHM for energies up to {approx}1 keV, and can be operated at total count rates of {approx}10{sup 6} counts/s. For increased quantum efficiency and cleaner response function, we have now started the development of Ta-based STJ detector arrays. Initial devices modeled after our Nb-based STJs have an energy resolution below 10 eV FWHM for X-ray energies below 1 keV, and pulse rise time discrimination can be used to improve their response function for energies up to several keV. We discuss the performance of the Ta-STJs and outline steps towards the next-generation of large STJ detector arrays with higher sensitivity.

  12. Development of Ta-based Superconducting Tunnel Junction X-ray Detectors for Fluorescence XAS

    SciTech Connect

    Friedrich, Stephan; Drury, Owen B.; Hall, John; Cantor, Robin

    2010-06-23

    We are developing superconducting tunnel junction (STJ) soft X-ray detectors for chemical analysis of dilute samples by fluorescence-detected X-ray absorption spectroscopy (XAS). Our 36-pixel Nb-based STJ spectrometer covers a solid angle {Omega}/4{pi}{approx_equal}10{sup -3}, offers an energy resolution of {approx}10-20 eV FWHM for energies up to {approx}1 keV, and can be operated at total count rates of {approx}10{sup 6} counts/s. For increased quantum efficiency and cleaner response function, we have now started the development of Ta-based STJ detector arrays. Initial devices modeled after our Nb-based STJs have an energy resolution below 10 eV FWHM for X-ray energies below 1 keV, and pulse rise time discrimination can be used to improve their response function for energies up to several keV. We discuss the performance of the Ta-STJs and outline steps towards the next-generation of large STJ detector arrays with higher sensitivity.

  13. Geometric filtration of classification-based object detectors in realtime road scene recognition systems

    NASA Astrophysics Data System (ADS)

    Prun, Viktor; Bocharov, Dmitry; Koptelov, Ivan; Sholomov, Dmitry; Postnikov, Vassily

    2015-12-01

    We study the issue of performance improvement of classification-based object detectors by including certain geometric-oriented filters. Configurations of the observed 3D scene may be used as a priori or a posteriori information for object filtration. A priori information is used to select only those object parameters (size and position on image plane) that are in accordance with the scene, restricting implausible combinations of parameters. On the other hand the detection robustness can be enhanced by rejecting detection results using a posteriori information about 3D scene. For example, relative location of detected objects can be used as criteria for filtration. We have included proposed filters in object detection modules of two different industrial vision-based recognition systems and compared the resulting detection quality before detectors improving and after. Filtering with a priori information leads to significant decrease of detector's running time per frame and increase of number of correctly detected objects. Including filter based on a posteriori information leads to decrease of object detection false positive rate.

  14. Evaluation of Compton gamma camera prototype based on pixelated CdTe detectors.

    PubMed

    Calderón, Y; Chmeissani, M; Kolstein, M; De Lorenzo, G

    2014-06-01

    A proposed Compton camera prototype based on pixelated CdTe is simulated and evaluated in order to establish its feasibility and expected performance in real laboratory tests. The system is based on module units containing a 2×4 array of square CdTe detectors of 10×10 mm(2) area and 2 mm thickness. The detectors are pixelated and stacked forming a 3D detector with voxel sizes of 2 × 1 × 2 mm(3). The camera performance is simulated with Geant4-based Architecture for Medicine-Oriented Simulations(GAMOS) and the Origin Ensemble(OE) algorithm is used for the image reconstruction. The simulation shows that the camera can operate with up to 10(4) Bq source activities with equal efficiency and is completely saturated at 10(9) Bq. The efficiency of the system is evaluated using a simulated (18) F point source phantom in the center of the Field-of-View (FOV) achieving an intrinsic efficiency of 0.4 counts per second per kilobecquerel. The spatial resolution measured from the point spread function (PSF) shows a FWHM of 1.5 mm along the direction perpendicular to the scatterer, making it possible to distinguish two points at 3 mm separation with a peak-to-valley ratio of 8. PMID:24932209

  15. Ion track reconstruction in 3D using alumina-based fluorescent nuclear track detectors.

    PubMed

    Niklas, M; Bartz, J A; Akselrod, M S; Abollahi, A; Jäkel, O; Greilich, S

    2013-09-21

    Fluorescent nuclear track detectors (FNTDs) based on Al2O3: C, Mg single crystal combined with confocal microscopy provide 3D information on ion tracks with a resolution only limited by light diffraction. FNTDs are also ideal substrates to be coated with cells to engineer cell-fluorescent ion track hybrid detectors (Cell-Fit-HD). This radiobiological tool enables a novel platform linking cell responses to physical dose deposition on a sub-cellular level in proton and heavy ion therapies. To achieve spatial correlation between single ion hits in the cell coating and its biological response the ion traversals have to be reconstructed in 3D using the depth information gained by the FNTD read-out. FNTDs were coated with a confluent human lung adenocarcinoma epithelial (A549) cell layer. Carbon ion irradiation of the hybrid detector was performed perpendicular and angular to the detector surface. In situ imaging of the fluorescently labeled cell layer and the FNTD was performed in a sequential read-out. Making use of the trajectory information provided by the FNTD the accuracy of 3D track reconstruction of single particles traversing the hybrid detector was studied. The accuracy is strongly influenced by the irradiation angle and therefore by complexity of the FNTD signal. Perpendicular irradiation results in highest accuracy with error of smaller than 0.10°. The ability of FNTD technology to provide accurate 3D ion track reconstruction makes it a powerful tool for radiobiological investigations in clinical ion beams, either being used as a substrate to be coated with living tissue or being implanted in vivo. PMID:23965401

  16. Ion track reconstruction in 3D using alumina-based fluorescent nuclear track detectors

    NASA Astrophysics Data System (ADS)

    Niklas, M.; Bartz, J. A.; Akselrod, M. S.; Abollahi, A.; Jäkel, O.; Greilich, S.

    2013-09-01

    Fluorescent nuclear track detectors (FNTDs) based on Al2O3: C, Mg single crystal combined with confocal microscopy provide 3D information on ion tracks with a resolution only limited by light diffraction. FNTDs are also ideal substrates to be coated with cells to engineer cell-fluorescent ion track hybrid detectors (Cell-Fit-HD). This radiobiological tool enables a novel platform linking cell responses to physical dose deposition on a sub-cellular level in proton and heavy ion therapies. To achieve spatial correlation between single ion hits in the cell coating and its biological response the ion traversals have to be reconstructed in 3D using the depth information gained by the FNTD read-out. FNTDs were coated with a confluent human lung adenocarcinoma epithelial (A549) cell layer. Carbon ion irradiation of the hybrid detector was performed perpendicular and angular to the detector surface. In situ imaging of the fluorescently labeled cell layer and the FNTD was performed in a sequential read-out. Making use of the trajectory information provided by the FNTD the accuracy of 3D track reconstruction of single particles traversing the hybrid detector was studied. The accuracy is strongly influenced by the irradiation angle and therefore by complexity of the FNTD signal. Perpendicular irradiation results in highest accuracy with error of smaller than 0.10°. The ability of FNTD technology to provide accurate 3D ion track reconstruction makes it a powerful tool for radiobiological investigations in clinical ion beams, either being used as a substrate to be coated with living tissue or being implanted in vivo.

  17. Development of a Timepix based detector for the NanoXCT project

    NASA Astrophysics Data System (ADS)

    Nachtrab, F.; Hofmann, T.; Speier, C.; Lučić, J.; Firsching, M.; Uhlmann, N.; Takman, P.; Heinzl, C.; Holmberg, A.; Krumm, M.; Sauerwein, C.

    2015-11-01

    The NanoXCT EU FP7 project [1] aims at developing a laboratory, i.e. bench top sized X-ray nano-CT system with a large field-of-view (FOV) for non-destructive testing needs in the micro- and nano-technology sector. The targeted voxel size is 50 nm at 0.175 mm FOV, the maximum FOV is 1 mm at 285 nm voxel size. Within the project a suitable X-ray source, detector and manipulation system have been developed. The system concept [2] omits the use of X-ray optics, to be able to provide a large FOV of up to 1 mm and to preserve the flexibility of state-of-the-art micro-CT systems. The targeted resolution will be reached via direct geometric magnification made possible by the development of a specialized high-flux nano-focus transmission X-ray tube. The end-user's demand for elemental analysis will be covered by energy-resolved measurement techniques, in particular a K-edge imaging method. Timepix [3] modules were chosen as the basis for the detector system, since a photon counting detector is advantageous for the long exposure times that come with very small focal spot sizes. Additional advantages are the small pixel size and adjustable energy threshold. To fulfill the requirements on field-of-view, a detector width 0> 300 pixels was needed. The NanoXCT detector consists of four Hexa modules with 500 μm silicon sensors supplied by X-ray Imaging Europe. An adapter board was developed to connect all four modules to one Fitpix3 readout. The final detector has an active area of 3072 × 512 pixels or approximately 17 × 3 cm2.In this contribution we present the development of the Timepix based NanoXCT detector, it's application in the NanoXCT project for CT and material specific measurements and the current status of results.

  18. Advanced microbolometer detectors for a next-generation uncooled FPA for space-based thermal remote sensing

    NASA Astrophysics Data System (ADS)

    Williamson, Fraser; Marchese, Linda; Baldenberger, Georges; Châteauneuf, François; Provencal, Francis; Caron, Jean-Sol; Dupont, Fabien; Osouf, Jocelyne; Couture, Patrick; Ngo Phong, Linh; Pope, Tim

    2009-02-01

    INO has established a VOx-based uncooled microbolometer detector technology and an expertise in the development of custom detectors and focal plane arrays. Thanks to their low power consumption and broadband sensitivity, uncooled microbolometer detectors are finding an increased number of applications in the field of space-based thermal remote sensing. A mission requirement study has identified at least seven applications with a need for data in the MWIR (3-8 μm), LWIR (8-15 μm) and or FIR (15-100 μm) wavelength bands. The requirement study points to the need for two main classes of uncooled thermal detectors, the first requiring small and fast detectors for MWIR and LWIR imaging with small ground sampling distance, and the second requiring larger detectors with sensitivity out to the FIR. In this paper, the simulation, design, microfabrication and radiometric testing of detectors for these two classes of requirements will be presented. The performance of the experimental detectors closely approach the mission requirements and show the potential of microbolometer technology to fulfill the requirements of future space based thermal imaging missions.

  19. New multicolor illumination system for automatic optical inspection

    NASA Astrophysics Data System (ADS)

    Xiong, Guangjie; Ma, Shuyuan; Nie, Xuejun; Tang, Xiaohua

    2010-10-01

    In automatic optical inspection (AOI), the illumination system affects the quality of input images and the result of image processing in the AOI. This paper developed a new multi-color illumination system specially used in the printed circuit board (PCB) inspection to detect a variety of defects in automated optical inspection system. The new illumination system consists of four kinds of colors of light emitting diode (LED) arrays composed of high-density LED surface light source. In order to detect a variety of defects, the radiation angle of the each LED array is different. The system uses a micro-controller to control the four sets of LED arrays, after acquisition of the image, which can self-adjust the light intensity of the illumination system based on the reference and comparison of histogram of the image in real time and can control different color LED array respectively according to the quality of the tested image. This paper analyzed the structural model of the illumination system and designed the control system. The experimental results show that the new illumination system has important performances such as uniform illumination, adjustable light intensity, fast response, lower heat and etc. The system can provide highly stable illumination for the AOI to obtain high-quality images effectively for detect the defects of PCB, and improve the defect detection rate and reduce the defects of the false alarm rate of AOI.

  20. A carbon nanotubes photoconductive detector for middle and far infrared regions based on porous silicon and a polyamide nylon polymer

    NASA Astrophysics Data System (ADS)

    Saleh, Wasan R.

    2015-06-01

    Sensitive and good response photoconductive detectors working in the middle and far infrared regions were fabricated. These detectors were fabricated based on multi and double walled carbon nanotube films and works at room temperature. The films were deposited on a porous silicon (PSi) nanosurface. The surfaces were functionalized by a thin layer of polyamide nylon polymer to improve the photoresponsivity of the fabricated detectors. The response time of the fabricated MWCNTs-PSi detectors were 30 and 0.22 ms for the middle and far IR region respectively. The functionalisation of the MWCNTs-PSi film surface by the polyamide nylon polymer improved the photoconductive gain, photoresponsivity, and specific conductivity in both MWCNTs-PSi and DWCNTs-PSi detectors. The designed carbon nanotube (CNT) based photodetector has low cost, high sensitivity and reasonable speed for the middle and far IR spectral range without cooling.

  1. Specimen illumination apparatus with optical cavity for dark field illumination

    DOEpatents

    Pinkel, Daniel; Sudar, Damir; Albertson, Donna

    1999-01-01

    An illumination apparatus with a specimen slide holder, an illumination source, an optical cavity producing multiple reflection of illumination light to a specimen comprising a first and a second reflective surface arranged to achieve multiple reflections of light to a specimen is provided. The apparatus can further include additional reflective surfaces to achieve the optical cavity, a slide for mounting the specimen, a coverslip which is a reflective component of the optical cavity, one or more prisms for directing light within the optical cavity, antifading solutions for improving the viewing properties of the specimen, an array of materials for analysis, fluorescent components, curved reflective surfaces as components of the optical cavity, specimen detection apparatus, optical detection equipment, computers for analysis of optical images, a plane polarizer, fiberoptics, light transmission apertures, microscopic components, lenses for viewing the specimen, and upper and lower mirrors above and below the specimen slide as components of the optical cavity. Methods of using the apparatus are also provided.

  2. Estimation of illuminator scintillation in laser-illuminated imagery

    NASA Astrophysics Data System (ADS)

    Dayton, David C.; Lasche, James B.

    2013-09-01

    It is well known that atmospheric turbulence corrupts the phase front of laser beam propagation. The phase distortions manifest themselves as intensity fluctuations when the beam is propagated over some distance. This intensity fluctuation is often referred to as scintillation. Laser illuminated imaging systems are used for a variety of applications including night time imaging and tracking. The illuminator intensity fluctuation is often considered a noise effect on the imagery, however if an estimate of the scintillation can be separated from the images, it would be useful in estimating atmospheric turbulence parameters. In past work we have used a Bayesian estimation approach to separate the illuminator fluctuations from the target images. In this paper we extend that approach to included calculations of the spatial and temporal statistics of the scintillation estimate to extract atmospheric turbulence parameters

  3. A pixellated γ-camera based on CdTe detectors clinical interests and performances

    NASA Astrophysics Data System (ADS)

    Chambron, J.; Arntz, Y.; Eclancher, B.; Scheiber, Ch; Siffert, P.; Hage Hali, M.; Regal, R.; Kazandjian, A.; Prat, V.; Thomas, S.; Warren, S.; Matz, R.; Jahnke, A.; Karman, M.; Pszota, A.; Nemeth, L.

    2000-07-01

    A mobile gamma camera dedicated to nuclear cardiology, based on a 15 cm×15 cm detection matrix of 2304 CdTe detector elements, 2.83 mm×2.83 mm×2 mm, has been developed with a European Community support to academic and industrial research centres. The intrinsic properties of the semiconductor crystals - low-ionisation energy, high-energy resolution, high attenuation coefficient - are potentially attractive to improve the γ-camera performances. But their use as γ detectors for medical imaging at high resolution requires production of high-grade materials and large quantities of sophisticated read-out electronics. The decision was taken to use CdTe rather than CdZnTe, because the manufacturer (Eurorad, France) has a large experience for producing high-grade materials, with a good homogeneity and stability and whose transport properties, characterised by the mobility-lifetime product, are at least 5 times greater than that of CdZnTe. The detector matrix is divided in 9 square units, each unit is composed of 256 detectors shared in 16 modules. Each module consists in a thin ceramic plate holding a line of 16 detectors, in four groups of four for an easy replacement, and holding a special 16 channels integrated circuit designed by CLRC (UK). A detection and acquisition logic based on a DSP card and a PC has been programmed by Eurorad for spectral and counting acquisition modes. Collimators LEAP and LEHR from commercial design, mobile gantry and clinical software were provided by Siemens (Germany). The γ-camera head housing, its general mounting and the electric connections were performed by Phase Laboratory (CNRS, France). The compactness of the γ-camera head, thin detectors matrix, electronic readout and collimator, facilitates the detection of close γ sources with the advantage of a high spatial resolution. Such an equipment is intended to bedside explorations. There is a growing clinical requirement in nuclear cardiology to early assess the extent of an

  4. Electrical properties of amorphous selenium based photoconductive devices for application in x-ray image detectors

    NASA Astrophysics Data System (ADS)

    Belev, Gueorgui Stoev

    In the last 10-15 years there has been a renewed interest in amorphous Se (a-Se) and its alloys due to their application as photoconductor materials in the new fully digital direct conversion flat panel x-ray medical image detectors. For a number of reasons, the a-Se photoconductor layer in such x-ray detectors has to be operated at very high electric fields (up to 10 V mum-1) and one of the most difficult problems related to such applications of a-Se is the problem of the dark current (the current in the absence of any radiation) minimization in the photoconductor layer. This PhD work has been devoted to researching the possibilities for dark current minimization in a-Se x-ray photoconductors devices through a systematic study of the charge transport (carrier mobility and carrier lifetimes) and dark currents in single and multilayered a-Se devices as a function of alloying, doping, deposition condition and other fabrication factors. The results of the studies are extensively discussed in the thesis. We have proposed a new technological method for dark current reduction in single and multilayered a-Se based photoconductor for x-ray detector applications. The new technology is based on original experimental findings which demonstrate that both hole transport and the dark currents in a-Se films are a very strong function of the substrate temperature (Tsubstrate) during the film deposition process. We have shown that the new technique reduces the dark currents to approximately the same levels as achievable with the previously existing methods for dark current reduction. However, the new method is simpler to implement, and offers some potential advantages, especially in cases when a very high image resolution (20 lp/mm) and/or fast pixel readout (>30 s-1) are needed. Using the new technology we have fabricated simple single and double (ni-like) photoconductor layers on prototype x-ray image detectors with CCD (Charge Coupled Device) readout circuits. Dark currents in

  5. A Comparison of Video-Based and Interaction-Based Affect Detectors in Physics Playground

    ERIC Educational Resources Information Center

    Kai, Shiming; Paquette, Luc; Baker, Ryan S.; Bosch, Nigel; D'Mello, Sidney; Ocumpaugh, Jaclyn; Shute, Valerie; Ventura, Matthew

    2015-01-01

    Increased attention to the relationships between affect and learning has led to the development of machine-learned models that are able to identify students' affective states in computerized learning environments. Data for these affect detectors have been collected from multiple modalities including physical sensors, dialogue logs, and logs of…

  6. A multiuser detector based on artificial bee colony algorithm for DS-UWB systems.

    PubMed

    Yin, Zhendong; Liu, Xiaohui; Wu, Zhilu

    2013-01-01

    Artificial Bee Colony (ABC) algorithm is an optimization algorithm based on the intelligent behavior of honey bee swarm. The ABC algorithm was developed to solve optimizing numerical problems and revealed premising results in processing time and solution quality. In ABC, a colony of artificial bees search for rich artificial food sources; the optimizing numerical problems are converted to the problem of finding the best parameter which minimizes an objective function. Then, the artificial bees randomly discover a population of initial solutions and then iteratively improve them by employing the behavior: moving towards better solutions by means of a neighbor search mechanism while abandoning poor solutions. In this paper, an efficient multiuser detector based on a suboptimal code mapping multiuser detector and artificial bee colony algorithm (SCM-ABC-MUD) is proposed and implemented in direct-sequence ultra-wideband (DS-UWB) systems under the additive white Gaussian noise (AWGN) channel. The simulation results demonstrate that the BER and the near-far effect resistance performances of this proposed algorithm are quite close to those of the optimum multiuser detector (OMD) while its computational complexity is much lower than that of OMD. Furthermore, the BER performance of SCM-ABC-MUD is not sensitive to the number of active users and can obtain a large system capacity. PMID:23983638

  7. Photon-statistics-based classical ghost imaging with one single detector.

    PubMed

    Kuhn, Simone; Hartmann, Sébastien; Elsäßer, Wolfgang

    2016-06-15

    We demonstrate a novel ghost imaging (GI) scheme based on one single-photon-counting detector with subsequent photon statistics analysis. The key idea is that instead of measuring correlations between the object and reference beams such as in standard GI schemes, the light of the two beams is superimposed. The photon statistics analysis of this mixed light allows us to determine the photon number distribution as well as to calculate the central second-order correlation coefficient. The image information is obtained as a function of the spatial resolution of the reference beam. The performance of this photon-statistics-based GI system with one single detector (PS-GI) is investigated in terms of visibility and resolution. Finally, the knowledge of the complete photon statistics allows easy access to higher correlation coefficients such that we are able to perform here third- and fourth-order GI. The PS-GI concept can be seen as a complement to already existing GI technologies thus enabling a broader dissemination of GI as a superior metrology technique, paving the road for new applications in particular with advanced photon counting detectors. PMID:27304308

  8. Comparison of spectral CT imaging methods based a photon-counting detector: Experimental study

    NASA Astrophysics Data System (ADS)

    Lee, Youngjin; Lee, Seungwan; Kim, Hee-Joung

    2016-04-01

    Photon-counting detectors allow spectral computed tomography (CT) imaging using energy-resolved information from a polychromatic X-ray spectrum. The spectral CT images based on the photon-counting detectors are dependent on the energy ranges defined by energy bins for image acquisition. In this study, K-edge and energy weighting imaging methods were experimentally implemented by using a spectral CT system with a cadmium zinc telluride (CZT)-based photon-counting detector. The spectral CT images were obtained by various energy bins and compared in terms of CNR improvement for investigating the effect of energy bins and the efficiency of the spectral CT imaging methods. The results showed that the spectral CT image quality was improved by using the particular energy bins, which were optimized for each spectral CT imaging method and target material. The CNR improvement was different for the spectral CT imaging methods and target materials. It can be concluded that an appropriate selection of imaging method for each target material and the optimization of energy bin can maximize the quality of spectral CT images.

  9. Grid artifact reduction for direct digital radiography detectors based on rotated stationary grids with homomorphic filtering

    SciTech Connect

    Kim, Dong Sik; Lee, Sanggyun

    2013-06-15

    Purpose: Grid artifacts are caused when using the antiscatter grid in obtaining digital x-ray images. In this paper, research on grid artifact reduction techniques is conducted especially for the direct detectors, which are based on amorphous selenium. Methods: In order to analyze and reduce the grid artifacts, the authors consider a multiplicative grid image model and propose a homomorphic filtering technique. For minimal damage due to filters, which are used to suppress the grid artifacts, rotated grids with respect to the sampling direction are employed, and min-max optimization problems for searching optimal grid frequencies and angles for given sampling frequencies are established. The authors then propose algorithms for the grid artifact reduction based on the band-stop filters as well as low-pass filters. Results: The proposed algorithms are experimentally tested for digital x-ray images, which are obtained from direct detectors with the rotated grids, and are compared with other algorithms. It is shown that the proposed algorithms can successfully reduce the grid artifacts for direct detectors. Conclusions: By employing the homomorphic filtering technique, the authors can considerably suppress the strong grid artifacts with relatively narrow-bandwidth filters compared to the normal filtering case. Using rotated grids also significantly reduces the ringing artifact. Furthermore, for specific grid frequencies and angles, the authors can use simple homomorphic low-pass filters in the spatial domain, and thus alleviate the grid artifacts with very low implementation complexity.

  10. A detector based on silica fibers for ion beam monitoring in a wide current range

    NASA Astrophysics Data System (ADS)

    Auger, M.; Braccini, S.; Carzaniga, T. S.; Ereditato, A.; Nesteruk, K. P.; Scampoli, P.

    2016-03-01

    A detector based on doped silica and optical fibers was developed to monitor the profile of particle accelerator beams of intensity ranging from 1 pA to tens of μA. Scintillation light produced in a fiber moving across the beam is measured, giving information on its position, shape and intensity. The detector was tested with a continuous proton beam at the 18 MeV Bern medical cyclotron used for radioisotope production and multi-disciplinary research. For currents from 1 pA to 20 μA, Ce3+ and Sb3+ doped silica fibers were used as sensors. Read-out systems based on photodiodes, photomultipliers and solid state photomultipliers were employed. Profiles down to the pA range were measured with this method for the first time. For currents ranging from 1 pA to 3 μA, the integral of the profile was found to be linear with respect to the beam current, which can be measured by this detector with an accuracy of ~1%. The profile was determined with a spatial resolution of 0.25 mm. For currents ranging from 5 μA to 20 μA, thermal effects affect light yield and transmission, causing distortions of the profile and limitations in monitoring capabilities. For currents higher than ~1 μA, non-doped optical fibers for both producing and transporting scintillation light were also successfully employed.

  11. Design and development of a fNIRS system prototype based on SiPM detectors

    NASA Astrophysics Data System (ADS)

    Sanfilippo, D.; Valvo, G.; Mazzillo, M.; Piana, A.; Carbone, B.; Renna, L.; Fallica, P. G.; Agrò, D.; Morsellino, G.; Pinto, M.; Canicattı, R.; Galioto, N.; Tomasino, A.; Adamo, G.; Stivala, S.; Parisi, A.; Curcio, L.; Giaconia, C.; Busacca, A. C.; Pagano, R.; Libertino, S.; Lombardo, S.

    2014-03-01

    Functional Near Infrared Spectroscopy (fNIRS) uses near infrared sources and detectors to measure changes in absorption due to neurovascular dynamics in response to brain activation. The use of Silicon Photomultipliers (SiPMs) in a fNIRS system has been estimated potentially able to increase the spatial resolution. Dedicated SiPM sensors have been designed and fabricated by using an optimized process. Electrical and optical characterizations are presented. The design and implementation of a portable fNIRS embedded system, hosting up to 64 IR-LED sources and 128 SiPM sensors, has been carried out. The system has been based on a scalable architecture whose elementary leaf is a flexible board with 16 SiPMs and 4 couples of LEDs each operating at two wavelengths. An ARM based microcontroller has been joined with a multiplexing interface, able to control power supply for the LEDs and collect data from the SiPMs in a time-sharing fashion and with configurable temporal slots. The system will be validated by using a phantom made by materials of different scattering and absorption indices layered to mimic a human head. A preliminary characterization of the optical properties of the single material composing the phantom has been performed using the SiPM in the diffuse radial reflectance measurement technique. The first obtained results confirm the high sensitivity of such kind of detector in the detection of weak light signal even at large distance between the light source and the detector.

  12. Low-power adaptive spike detector based on a sigma-delta control loop.

    PubMed

    Gagnon-Turcotte, G; Sawan, M; Gosselin, B

    2015-08-01

    This paper presents a resources-optimized digital action potential (AP) detector featuring an adaptive threshold based on a new Sigma-delta control loop. The proposed AP detector is optimized for utilizing low hardware resources, which makes it suitable for implementation on most popular low-power microcontrollers units (MCU). The adaptive threshold is calculated using a digital control loop based on a Sigma-delta modulator that precisely estimates the standard deviation of the amplitude of the neuronal signal. The detector was implemented on a popular low-power MCU and fully characterized experimentally using previously recorded neural signals with different signal-to-noise ratios. A comparison of the obtained results with other thresholding approaches shows that the proposed method can compete with high performance and highly resources demanding spike detection approaches while achieving up to 100% of true positive detection rate at high SNR, and up to 63% for an SNR as low as 0 dB, while necessitating an execution time as low as 11 μs with the MCU operating at 8 MHz. PMID:26736719

  13. Detectability and Parameter Estimation of Gravitational Waves from Cosmic String with Ground-Based Detectors

    NASA Astrophysics Data System (ADS)

    Yuzurihara, Hirotaka; Kanda, Nobuyuki

    Cosmic string is one dimensional topological defects which might be formed at the phase transition in the early universe. Gravitational Wave (GW) waveform and its power spectrum from structure in closed cosmic string loop that is called as "cusp" are theoretically predicted. Cosmic string is thought to be described with two characteristic parameters: string tension μ and initial loop size α. We demonstrate numerical simulation for GWs from closed comic string loops to study detectability and parameter decision with ground-based detectors, such as KAGRA, advanced LIGO, advanced Virgo and LIGO-India. We employ characteristic parameters 10 - 13 < Gμ < 10 - 7 and 10 - 16 < α < 10 - 1, assuming uniform distribution of cosmic string in isotropic direction, at time epochs of loop forming and GW emission according to the universe model. We calculate waveform numerically in time domain of each GW from these distributed cosmic strings, and superpose waveforms to generate continuously observational signal on the ground-based GW detectors, including detector responses. We consider data analysis for stochastic background type gravitational wave signatures in the observation.

  14. Moonbase night power by laser illumination

    NASA Technical Reports Server (NTRS)

    Landis, Geoffrey A.

    1992-01-01

    Moonbase solar-power concepts must somehow address the energy storage problem posed by the 354-hour lunar night. Attention is presently given to the feasibility of laser-array illumination of a lunar base, using technology that is projected to be available in the near term. Beam-spreading due to atmospheric distortions could be reduced through the use of adaptive optics to compensate for atmospheric turbulence.

  15. A 1200 element detector system for synchrotron-based coronary angiography

    SciTech Connect

    Thompson, A.C.; Lavender, W.M.; Rubenstein, E.; Giacomini, J.C.; Rosso, V.; Schulze, C.; Chapman, D.; Thomlinson, W.

    1993-08-23

    A 1200 channel Si(Li) detector system has been developed for transvenous coronary angiography experiments using synchrotron radiation. It is part of the synchrotron medical imaging facility at the National Synchrotron Light Source. The detector is made from a single crystal of lithium-drifted silicon with an active area 150 mm long {times} 11 mm high {times} 5 mm thick. The elements are arranged in two parallel rows of 600 elements with a center-to-center spacing of 0.25 mm. All 1200 elements are read out simultaneously every 4 ms. A Intel 80486 based computer with a high speed digital signal processing interface is used to control the beamline hardware and to acquire a series of images. The signal-to-noise, linearity and resolution of the system have been measured. Human images have been taken with this system.

  16. Comparison of atom interferometers and light interferometers as space-based gravitational wave detectors.

    PubMed

    Baker, John G; Thorpe, J I

    2012-05-25

    We consider a class of proposed gravitational-wave detectors based on multiple atomic interferometers separated by large baselines and referenced by common laser systems. We compute the sensitivity limits of these detectors due to intrinsic phase noise of the light sources, noninertial motion of the light sources, and atomic shot noise and compare them to sensitivity limits for traditional light interferometers. We find that atom interferometers and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g., multiple-arm instruments) to reach interesting sensitivities. The sensitivity limit from motion of the light sources is slightly different and, in principle, favors the atom interferometers in the low-frequency limit, although the limit in both cases is severe. PMID:23003235

  17. Continuous emission monitoring system based on a PbSe detector array

    NASA Astrophysics Data System (ADS)

    Pujadas, Manuel; Oche, A.; Barcala, J. M.; Teres, J.

    1995-09-01

    PbSe is a very important photoconductive material extensively used as IR detector for military applications and may be considered one of the most useful materials for detection in the MIR range. In the last years the opening of its production for wide civil use has allowed the conception of new detection systems based on this semiconductor. Considering some possible applications of it in environmental control, PbSe can provide, for instance, good response band to monitor several gases of major importance (SO2, NO, CO, etc.), especially when their concentrations are high. In this paper, we present applications of this semiconductor for this purpose: the developemnt of a new continuous emission monitoring system (CEMS) using a PbSe detector array in a nondispersive configuration. The basics of this prototype and some experimental results related to the detection of different typical emission gases with this system are presented here.

  18. Terahertz response of NbN-based microwave kinetic inductance detectors with rewound spiral resonator

    NASA Astrophysics Data System (ADS)

    Ariyoshi, S.; Nakajima, K.; Saito, A.; Taino, T.; Otani, C.; Yamada, H.; Ohshima, S.; Bae, J.; Tanaka, S.

    2016-03-01

    We have developed microwave kinetic inductance detectors (MKIDs) consisting of dual-purpose rewound spirals (spiral-MKIDs) made of a metal nitride superconductor for terahertz imaging applications. An NbN-based spiral-MKID array with 25 pixels was fabricated, and the fundamental performance of the terahertz receptivity was evaluated at the equilibrium temperature of a conventional 4He refrigerator (≃3 K). The microwave transmission property of the array showed the 25 resonance lines, equally separated by frequency, in the microwave range from 2.70 to 2.95 GHz. To evaluate its optical performance as a terahertz detector, we measured the spiral-MKID’s spectral response, response time, and noise equivalent power (NEP), and confirmed that it revealed a broad spectral response from 1 to 9 THz and an effective response time of approximately 80 μs. The noise-equivalent power was estimated to be {10}-13 {{W}}/\\sqrt{{Hz}}.

  19. Natural gas pipeline leak detector based on NIR diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Gao, Xiaoming; Fan, Hong; Huang, Teng; Wang, Xia; Bao, Jian; Li, Xiaoyun; Huang, Wei; Zhang, Weijun

    2006-09-01

    The paper reports on the development of an integrated natural gas pipeline leak detector based on diode laser absorption spectroscopy. The detector transmits a 1.653 μm DFB diode laser with 10 mW and detects a fraction of the backscatter reflected from the topographic targets. To eliminate the effect of topographic scatter targets, a ratio detection technique was used. Wavelength modulation and harmonic detection were used to improve the detection sensitivity. The experimental detection limit is 50 ppm m, remote detection for a distance up to 20 m away topographic scatter target is demonstrated. Using a known simulative leak pipe, minimum detectable pipe leak flux is less than 10 ml/min.

  20. Natural gas pipeline leak detector based on NIR diode laser absorption spectroscopy.

    PubMed

    Gao, Xiaoming; Fan, Hong; Huang, Teng; Wang, Xia; Bao, Jian; Li, Xiaoyun; Huang, Wei; Zhang, Weijun

    2006-09-01

    The paper reports on the development of an integrated natural gas pipeline leak detector based on diode laser absorption spectroscopy. The detector transmits a 1.653 microm DFB diode laser with 10 mW and detects a fraction of the backscatter reflected from the topographic targets. To eliminate the effect of topographic scatter targets, a ratio detection technique was used. Wavelength modulation and harmonic detection were used to improve the detection sensitivity. The experimental detection limit is 50 ppmm, remote detection for a distance up to 20 m away topographic scatter target is demonstrated. Using a known simulative leak pipe, minimum detectable pipe leak flux is less than 10 ml/min. PMID:16563854