WorldWideScience

Sample records for heterodyne imaging array

  1. Next generation heterodyne array for JCMT

    Science.gov (United States)

    Chen, M.-T.; Dempsey, J.; Ho, P. T. P.; Friberg, P.; Bintley, D.; Walther, C.

    2016-07-01

    As part of the JCMT Future Instrumentation Project, the EAO looks to optimize the premier niche of the facility as the go-to telescope for fast, deep wide-field mapping of the universe at 345 GHz (850 um). The next generation heterodyne array for JCMT will be designed to provide deep ultra-fast mapping capabilities that takes advantage of the full field-of-view available to the telescope, and an array of 90 SIS mixers. This paper presents a preliminary design options and the critical science drivers for the project.

  2. Imaging doppler velocimeter with downward heterodyning in the optical domain

    Science.gov (United States)

    Reu, Phillip L; Hansche, Bruce D

    2013-05-21

    In a Doppler velocimeter, the incoming Doppler-shifted beams are heterodyned to reduce their frequencies into the bandwidth of a digital camera. This permits the digital camera to produce at every sampling interval a complete two-dimensional array of pixel values. This sequence of pixel value arrays provides a velocity image of the target.

  3. Alignment error analysis of detector array for spatial heterodyne spectrometer.

    Science.gov (United States)

    Jin, Wei; Chen, Di-Hu; Li, Zhi-Wei; Luo, Hai-Yan; Hong, Jin

    2017-12-10

    Spatial heterodyne spectroscopy (SHS) is a new spatial interference spectroscopy which can achieve high spectral resolution. The alignment error of the detector array can lead to a significant influence with the spectral resolution of a SHS system. Theoretical models for analyzing the alignment errors which are divided into three kinds are presented in this paper. Based on these models, the tolerance angle of these errors has been given, respectively. The result of simulation experiments shows that when the angle of slope error, tilt error, and rotation error are less than 1.21°, 1.21°, 0.066° respectively, the alignment reaches an acceptable level.

  4. Range imager performance comparison in homodyne and heterodyne operating modes

    Science.gov (United States)

    Conroy, Richard M.; Dorrington, Adrian A.; Künnemeyer, Rainer; Cree, Michael J.

    2009-01-01

    Range imaging cameras measure depth simultaneously for every pixel in a given field of view. In most implementations the basic operating principles are the same. A scene is illuminated with an intensity modulated light source and the reflected signal is sampled using a gain-modulated imager. Previously we presented a unique heterodyne range imaging system that employed a bulky and power hungry image intensifier as the high speed gain-modulation mechanism. In this paper we present a new range imager using an internally modulated image sensor that is designed to operate in heterodyne mode, but can also operate in homodyne mode. We discuss homodyne and heterodyne range imaging, and the merits of the various types of hardware used to implement these systems. Following this we describe in detail the hardware and firmware components of our new ranger. We experimentally compare the two operating modes and demonstrate that heterodyne operation is less sensitive to some of the limitations suffered in homodyne mode, resulting in better linearity and ranging precision characteristics. We conclude by showing various qualitative examples that demonstrate the system's three-dimensional measurement performance.

  5. HARP : A submillimetre heterodyne array receiver operating on the James Clerk Maxwell Telescope

    NARCIS (Netherlands)

    Smith, H.; Buckle, J.; Hills, R.; Bell, G.; Richer, J.; Curtis, E.; Withington, S.; Leech, J.; Williamson, R.; Klapwijk, T.M.

    2008-01-01

    This paper describes the key design features and performance of HARP, an innovative heterodyne focal-plane array receiver designed and built to operate in the submillimetre on the James Clerk Maxwell Telescope (JCMT) in Hawaii. The 4x4 element array uses SIS detectors, and is the first

  6. Recording multiple spatially-heterodyned direct to digital holograms in one digital image

    Science.gov (United States)

    Hanson, Gregory R [Clinton, TN; Bingham, Philip R [Knoxville, TN

    2008-03-25

    Systems and methods are described for recording multiple spatially-heterodyned direct to digital holograms in one digital image. A method includes digitally recording, at a first reference beam-object beam angle, a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram to sit on top of a first spatial-heterodyne carrier frequency defined by the first reference beam-object beam angle; digitally recording, at a second reference beam-object beam angle, a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram to sit on top of a second spatial-heterodyne carrier frequency defined by the second reference beam-object beam angle; applying a first digital filter to cut off signals around the first original origin and define a first result; performing a first inverse Fourier transform on the first result; applying a second digital filter to cut off signals around the second original origin and define a second result; and performing a second inverse Fourier transform on the second result, wherein the first reference beam-object beam angle is not equal to the second reference beam-object beam angle and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

  7. THz Direct Detector and Heterodyne Receiver Arrays in Silicon Nanoscale Technologies

    Science.gov (United States)

    Grzyb, Janusz; Pfeiffer, Ullrich

    2015-10-01

    The main scope of this paper is to address various implementation aspects of THz detector arrays in the nanoscale silicon technologies operating at room temperatures. This includes the operation of single detectors, detectors operated in parallel (arrays), and arrays of detectors operated in a video-camera mode with an internal reset to support continuous-wave illumination without the need to synchronize the source with the camera (no lock-in receiver required). A systematic overview of the main advantages and limitations in using silicon technologies for THz applications is given. The on-chip antenna design challenges and co-design aspects with the active circuitry are thoroughly analyzed for broadband detector/receiver operation. A summary of the state-of-the-art arrays of broadband THz direct detectors based on two different operation principles is presented. The first is based on the non-quasistatic resistive mixing process in a MOSFET channel, whereas the other relies on the THz signal rectification by nonlinearity of the base-emitter junction in a high-speed SiGe heterojunction bipolar transistor (HBT). For the MOSFET detector arrays implemented in a 65 nm bulk CMOS technology, a state-of-the-art optical noise equivalent power (NEP) of 14 pW/ at 720 GHz was measured, whereas for the HBT detector arrays in a 0.25 μm SiGe process technology, an optical NEP of 47 pW/ at 700 GHz was found. Based on the implemented 1k-pixel CMOS camera with an average power consumption of 2.5 μW/pixel, various design aspects specific to video-mode operation are outlined and co-integration issues with the readout circuitry are analyzed. Furthermore, a single-chip 2 × 2 array of heterodyne receivers for multi-color active imaging in a 160-1000 GHz band is presented with a well-balanced NEP across the operation bandwidth ranging from 0.1 to 0.24 fW/Hz (44.1-47.8 dB single-sideband NF) and an instantaneous IF bandwidth of 10 GHz. In its present implementation, the receiver RF

  8. Methods, compositions and kits for imaging cells and tissues using nanoparticles and spatial frequency heterodyne imaging

    Science.gov (United States)

    Rose-Petruck, Christoph; Wands, Jack R.; Rand, Danielle; Derdak, Zoltan; Ortiz, Vivian

    2016-04-19

    Methods, compositions, systems, devices and kits are provided herein for preparing and using a nanoparticle composition and spatial frequency heterodyne imaging for visualizing cells or tissues. In various embodiments, the nanoparticle composition includes at least one of: a nanoparticle, a polymer layer, and a binding agent, such that the polymer layer coats the nanoparticle and is for example a polyethylene glycol, a polyelectrolyte, an anionic polymer, or a cationic polymer, and such that the binding agent that specifically binds the cells or the tissue. Methods, compositions, systems, devices and kits are provided for identifying potential therapeutic agents in a model using the nanoparticle composition and spatial frequency heterodyne imaging.

  9. Background free CARS imaging by phase sensitive heterodyne CARS

    OpenAIRE

    Jurna, M.; Korterik, Jeroen P.; Otto, Cornelis; Herek, Jennifer Lynn; Offerhaus, Herman L.

    2008-01-01

    In this article we show that heterodyne CARS, based on a controlled and stable phase-preserving chain, can be used to measure amplitude and phase information of molecular vibration modes. The technique is validated by a comparison of the imaginary part of the heterodyne CARS spectrum to the spontaneous Raman spectrum of polyethylene. The detection of the phase allows for rejection of the non-resonant background from the data. The resulting improvement of the signal to noise ratio is shown by ...

  10. Complete Two-dimensional Muellermetric Imaging of Biological Tissue Using Heterodyned Optical Coherence Tomography

    CERN Document Server

    Liu, Xue; Shahriar, M S

    2010-01-01

    A polarization-sensitive optical coherence tomography system based on heterodyning and filtering techniques is built to perform Stokesmetric imaging of different layers of depths in a porcine tendon sample. The complete 4\\times4 backscattering Muellermetric images of one layer are acquired using such a system. The images reveal information indiscernible from a conventional OCT system.

  11. Saturation effects in heterodyne detection with Geiger-mode InGaAs avalanche photodiode detector arrays.

    Science.gov (United States)

    Luu, Jane X; Jiang, Leaf A

    2006-06-01

    We report, to the best of our knowledge, the first demonstration of heterodyne detection of a glint target using an InGaAs avalanche photodiode detector (APD) array in the Geiger mode. Due to the finite number of pixels, all such photon-counting arrays necessarily suffer from saturation effects. At large photon fluxes, saturation of the APD degrades the Doppler frequency resolution and the signal-to-noise ratio (SNR). We derive analytical expressions for the Doppler resolution and SNR, taking saturation effects into account. The optimal local oscillator power can be obtained numerically from the SNR expression.

  12. Super-Resolution Far-Field Infrared Imaging by Photothermal Heterodyne Imaging.

    Science.gov (United States)

    Li, Zhongming; Aleshire, Kyle; Kuno, Masaru; Hartland, Gregory V

    2017-09-21

    Infrared (IR) imaging provides chemical-specific information without the need for exogenous labels. Conventional far-field IR imaging techniques are diffraction limited, which means an effective spatial resolution of >5 μm with currently available optics. In this article, we present a novel far-field IR imaging technique based on photothermal heterodyne imaging (IR-PHI). In our version of IR-PHI, an IR pump laser excites the sample, causing a small temperature rise that is detected by a counterpropagating visible probe beam. Images and spectra of several different types of soft matter systems (polystyrene beads, thin polymer films, and single Escherichia coli bacterial cells) are presented to demonstrate the sensitivity and versatility of the technique. Importantly, the spatial resolution in the IR-PHI measurements is determined by the visible probe beam: a spatial resolution of 0.3 μm was achieved with a 0.53 μm probe wavelength and a high numerical aperture focusing objective. This is the highest spatial resolution reported to date for far-field IR imaging. Analysis of the experiments shows that for polymer beads in a dry environment, the magnitude of the IR-PHI signal is determined by the scattering cross section of the nano-object at the probe wavelength. This is in contrast to conventional PHI experiments in a heat-transfer medium, where the signal scales as the absorption cross section. This different scaling can be understood through the optical theorem. Our analysis also shows that both thermal expansion and changes in the refractive index of the material are important and that these two effects, in general, counteract each other.

  13. Phased array imaging

    Science.gov (United States)

    1990-09-01

    The problem of recoverable image resolution is investigated for the case where an imaging array is used which array has an optical transfer function that may be described as consisting of islands of nonzero value in a sea of zero values. Can the missing spatial frequency information can be provided--can, in effect, a form of (interpolative) super resolution. The CLEAN algorithm used by radio astronomers suggests that this should be possible. The results developed here indicate that this can be done, with no significant price in terms of signal-to-noise ratio to be paid, and further show that a nonlinear algorithm, like CLEAN, is not required. The results show that the feasibility of doing this depends on the angular size of the object being imaged. We find that its size must be less than the inverse of the largest gap between islands in the array's optical transfer function.

  14. The kilopixel array pathfinder project (KAPPa), a 16-pixel integrated heterodyne focal plane array: characterization of the single pixel prototype

    Science.gov (United States)

    Wheeler, Caleb H.; Groppi, Christopher E.; Mani, Hamdi; McGarey, Patrick; Kuenzi, Linda; Weinreb, Sander; Russell, Damon S.; Kooi, Jacob W.; Lichtenberger, Arthur W.; Walker, Christopher K.; Kulesa, Craig

    2014-07-01

    We report on the laboratory testing of KAPPa, a 16-pixel proof-of-concept array to enable the creation THz imaging spectrometer with ~1000 pixels. Creating an array an order of magnitude larger than the existing state of the art of 64 pixels requires a simple and robust design as well as improvements to mixer selection, testing, and assembly. Our testing employs a single pixel test bench where a novel 2D array architecture is tested. The minimum size of the footprint is dictated by the diameter of the drilled feedhorn aperture. In the adjoining detector block, a 6mm × 6mm footprint houses the SIS mixer, LNA, matching and bias networks, and permanent magnet. We present an initial characterization of the single pixel prototype using a computer controlled test bench to determine Y-factors for a parameter space of LO power, LO frequency, IF bandwidth, magnet field strength, and SIS bias voltage. To reduce the need to replace poorly preforming pixels that are already mounted in a large format array, we show techniques to improve SIS mixer selection prior to mounting in the detector block. The 2D integrated 16-pixel array design has been evolved as we investigate the properties of the single pixel prototype. Carful design of the prototype has allowed for rapid translation of single pixel design improvements to be easily incorporated into the 16-pixel model.

  15. CCAT Heterodyne Instrument Development Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A key challenge in building a large pixel heterodyne array is efficiently and simultaneously delivering the astronomical signal and local oscillator power to each...

  16. Photon heterodyning.

    Science.gov (United States)

    Okawa, Youhei; Omura, Fuminori; Yasutake, Yuhsuke; Fukatsu, Susumu

    2017-08-21

    Single-photon interference experiments are attempted in the time domain using true single-photon streams. Self-heterodyning beats are clearly observed by letting the field associated with a single photon interfere with itself on a field-quadratic detector, which is a time analogue of Young's two-slit interference experiment. The temporal first-order coherence of single-photon fields, i.e., transient interference fringes, develops as cumulative detection events are mapped point-by-point onto a virtual capture frame by properly correlating the time-series data. The ability to single out photon counts at a designated timing paves the way for digital heterodyning with faint light for such use as phase measurement and quantum information processing.

  17. Laser Heterodyning

    CERN Document Server

    Protopopov, Vladimir V

    2009-01-01

    Laser heterodyning is now a widespread optical technique, based on interference of two waves with slightly different frequencies within the sensitive area of a photo-detector. Its unique feature – preserving phase information about optical wave in the electrical signal of the photo-detector – finds numerous applications in various domains of applied optics and optoelectronics: in spectroscopy, polarimetry, radiometry, laser radars and Lidars, microscopy and other areas. The reader may be surprised by a variety of disciplines that this book covers and satisfied by detailed explanation of the phenomena. Very well illustrated, this book will be helpful for researches, postgraduates and students, working in applied optics.

  18. Phase imaging and detection in pseudo-heterodyne scattering scanning near-field optical microscopy measurements.

    Science.gov (United States)

    Moreno, Camilo; Alda, Javier; Kinzel, Edward; Boreman, Glenn

    2017-02-01

    When considering the pseudo-heterodyne mode for detection of the modulus and phase of the near field from scattering scanning near-field optical microscopy (s-SNOM) measurements, processing only the modulus of the signal may produce an undesired constraint in the accessible values of the phase of the near field. A two-dimensional analysis of the signal provided by the data acquisition system makes it possible to obtain phase maps over the whole [0, 2π) range. This requires post-processing of the data to select the best coordinate system in which to represent the data along the direction of maximum variance. The analysis also provides a quantitative parameter describing how much of the total variance is included within the component selected for calculation of the modulus and phase of the near field. The dependence of the pseudo-heterodyne phase on the mean position of the reference mirror is analyzed, and the evolution of the global phase is extracted from the s-SNOM data. The results obtained from this technique compared well with the expected maps of the near-field phase obtained from simulations.

  19. Scanning strategies for imaging arrays

    Science.gov (United States)

    Kovács, Attila

    2008-07-01

    Large-format (sub)millimeter wavelength imaging arrays are best operated in scanning observing modes rather than traditional position-switched (chopped) modes. The choice of observing mode is critical for isolating source signals from various types of noise interference, especially for ground-based instrumentation operating under a bright atmosphere. Ideal observing strategies can combat 1/f noise, resist instrumental defects, sensitively recover emission on large scales, and provide an even field coverage - all under feasible requirements of telescope movement. This work aims to guide the design of observing patterns that maximize scientific returns. It also compares some of the popular choices of observing modes for (sub)millimeter imaging, such as random, Lissajous, billiard, spiral, On-The-Fly (OTF), DREAM, chopped and stare patterns. Many of the conclusions are also applicable other imaging applications and imaging in one dimension (e.g. spectroscopic observations).

  20. Infrared laser transillumination CT imaging system using parallel fiber arrays and optical switches for finger joint imaging

    Science.gov (United States)

    Sasaki, Yoshiaki; Emori, Ryota; Inage, Hiroki; Goto, Masaki; Takahashi, Ryo; Yuasa, Tetsuya; Taniguchi, Hiroshi; Devaraj, Balasigamani; Akatsuka, Takao

    2004-05-01

    The heterodyne detection technique, on which the coherent detection imaging (CDI) method founds, can discriminate and select very weak, highly directional forward scattered, and coherence retaining photons that emerge from scattering media in spite of their complex and highly scattering nature. That property enables us to reconstruct tomographic images using the same reconstruction technique as that of X-Ray CT, i.e., the filtered backprojection method. Our group had so far developed a transillumination laser CT imaging method based on the CDI method in the visible and near-infrared regions and reconstruction from projections, and reported a variety of tomographic images both in vitro and in vivo of biological objects to demonstrate the effectiveness to biomedical use. Since the previous system was not optimized, it took several hours to obtain a single image. For a practical use, we developed a prototype CDI-based imaging system using parallel fiber array and optical switches to reduce the measurement time significantly. Here, we describe a prototype transillumination laser CT imaging system using fiber-optic based on optical heterodyne detection for early diagnosis of rheumatoid arthritis (RA), by demonstrating the tomographic imaging of acrylic phantom as well as the fundamental imaging properties. We expect that further refinements of the fiber-optic-based laser CT imaging system could lead to a novel and practical diagnostic tool for rheumatoid arthritis and other joint- and bone-related diseases in human finger.

  1. Handheld ultrasound array imaging device

    Science.gov (United States)

    Hwang, Juin-Jet; Quistgaard, Jens

    1999-06-01

    A handheld ultrasound imaging device, one that weighs less than five pounds, has been developed for diagnosing trauma in the combat battlefield as well as a variety of commercial mobile diagnostic applications. This handheld device consists of four component ASICs, each is designed using the state of the art microelectronics technologies. These ASICs are integrated with a convex array transducer to allow high quality imaging of soft tissues and blood flow in real time. The device is designed to be battery driven or ac powered with built-in image storage and cineloop playback capability. Design methodologies of a handheld device are fundamentally different to those of a cart-based system. As system architecture, signal and image processing algorithm as well as image control circuit and software in this device is deigned suitably for large-scale integration, the image performance of this device is designed to be adequate to the intent applications. To elongate the battery life, low power design rules and power management circuits are incorporated in the design of each component ASIC. The performance of the prototype device is currently being evaluated for various applications such as a primary image screening tool, fetal imaging in Obstetrics, foreign object detection and wound assessment for emergency care, etc.

  2. Plane wave imaging using phased array

    NARCIS (Netherlands)

    Volker, A.W.F.

    2014-01-01

    Phased arrays are often used for rapid inspections. Phased arrays can be used to synthesize different wave fronts. For imaging, focused wave fronts are frequently used. In order to build an image, the phased array has to be fired multiple times at the same location. Alternatively, different data

  3. ISPA (imaging silicon pixel array) experiment

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    Application components of ISPA tubes are shown: the CERN-developed anode chip, special windows for gamma and x-ray detection, scintillating crystal and fibre arrays for imaging and tracking of ionizing particles.

  4. Faster processing of multiple spatially-heterodyned direct to digital holograms

    Science.gov (United States)

    Hanson, Gregory R [Clinton, TN; Bingham, Philip R [Knoxville, TN

    2008-09-09

    Systems and methods are described for faster processing of multiple spatially-heterodyned direct to digital holograms. A method includes of obtaining multiple spatially-heterodyned holograms, includes: digitally recording a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; digitally recording a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a first angle between a first reference beam and a first object beam; applying a first digital filter to cut off signals around the first original origin and performing an inverse Fourier transform on the result; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a second angle between a second reference beam and a second object beam; and applying a second digital filter to cut off signals around the second original origin and performing an inverse Fourier transform on the result, wherein digitally recording the first spatially-heterodyned hologram is completed before digitally recording the second spatially-heterodyned hologram and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

  5. Faster processing of multiple spatially-heterodyned direct to digital holograms

    Science.gov (United States)

    Hanson, Gregory R.; Bingham, Philip R.

    2006-10-03

    Systems and methods are described for faster processing of multiple spatially-heterodyned direct to digital holograms. A method includes of obtaining multiple spatially-heterodyned holograms, includes: digitally recording a first spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; digitally recording a second spatially-heterodyned hologram including spatial heterodyne fringes for Fourier analysis; Fourier analyzing the recorded first spatially-heterodyned hologram by shifting a first original origin of the recorded first spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a first angle between a first reference beam and a first, object beam; applying a first digital filter to cut off signals around the first original origin and performing an inverse Fourier transform on the result; Fourier analyzing the recorded second spatially-heterodyned hologram by shifting a second original origin of the recorded second spatially-heterodyned hologram including spatial heterodyne fringes in Fourier space to sit on top of a spatial-heterodyne carrier frequency defined as a second angle between a second reference beam and a second object beam; and applying a second digital filter to cut off signals around the second original origin and performing an inverse Fourier transform on the result, wherein digitally recording the first spatially-heterodyned hologram is completed before digitally recording the second spatially-heterodyned hologram and a single digital image includes both the first spatially-heterodyned hologram and the second spatially-heterodyned hologram.

  6. Spin scan tomographic array-based imager.

    Science.gov (United States)

    Hovland, Harald

    2014-12-29

    This work presents a novel imaging device based on tomographic reconstruction. Similar in certain aspects to the earlier presented tomographic scanning (TOSCA) principle, it provides several important enhancements. The device described generates a stream of one-dimensional projections from a linear array of thin stripe detectors onto which the (circular) image of the scene is rotated. A two-dimensional image is then reproduced from the one-dimensional signals using tomographic processing techniques. A demonstrator is presented. Various aspects of the design and construction are discussed, and resulting images and movies are presented.

  7. ISPA (imaging silicon pixel array) experiment

    CERN Document Server

    Patrice Loïez

    2002-01-01

    On the table, under the scrutiny of some collaboration members, an ISPA tube (upper-left of the table) with some of its application components is shown: they consist of the CERN-developed anode chip, special windows for gamma and x-ray detection, scintillating crystal and fibre arrays for imaging and tracking of ionizing particles.

  8. Spatial Heterodyne Spectrometer for Aviation Hazard Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Physical Sciences Inc (PSI) proposes the development of a longwave infrared (LWIR) imaging spatial heterodyne spectrometer (I-SHS) for standoff detection of clear...

  9. Multispectral filter array design without training images

    Science.gov (United States)

    Shinoda, Kazuma; Yanagi, Yudai; Hayasaki, Yoshio; Hasegawa, Madoka

    2017-08-01

    Multispectral images (MSIs) have been studied for many applications; however, limitations persist in techniques to capture them due to the complexity of assembling one or more prisms and multiple sensor arrays in order to detect signals. Inspired by the application of color filter arrays to commercial digital RGB cameras, a number of researchers have studied multispectral filter arrays (MSFAs) to solve this problem. Determining the measurement wavelength and pattern of an MSFA is important for improving the quality of the demosaicked image. Some conventional studies for designing MSFAs have used training data and have optimized the measurement wavelengths and the pattern by iteratively minimizing the error between the training data and the demosaicked images. We propose a metric to evaluate an MSFA without MSIs, and optimize the measurement wavelengths and the pattern of the MSFA by minimizing the metric. The proposed metric measures the sampling distance between filters in a spatial-spectral domain and quantifies the dispersion of the sampling points by average nearest-neighbor distance (ANND) under a given arbitrary MSFA. Since the quality of the demosaicked image is assumed to be proportional to the degree of dispersion of the sampling points in the spatial-spectral domain, we optimize the MSFA by minimizing the ANND in a nested simulated annealing process. Experimental results show that the optimized MSFA obtained using our method attained a higher peak signal-to-noise ratio (PSNR) than conventional untrained MSFAs in many cases. In addition, the performance difference between some trained MSFAs and the proposed MSFA was small. We also confirmed the validity of the proposed ANND by a comparison with the mean square error obtained from MSI datasets.

  10. Image Filtering with Field Programmable Gate Array

    Directory of Open Access Journals (Sweden)

    Arūnas Šlenderis

    2013-05-01

    Full Text Available The research examined the use of field programmable gate arrays (FPGA in image filtering. Experimental and theoretical researches were reviewed. Experiments with Cyclone III family FPGA chip with implemented NIOS II soft processor were considered. Image filtering was achieved with symmetrical and asymmetrical finite impulse response filters with convolution kernel. The system, which was implemented with 3×3 symmetrical filter, which was implemented using the hardware description language, uses 59% of logic elements of the chip and 10 multiplication elements. The system with asymmetrical filter uses the same amount of logic elements and 13 multiplication elements. Both filter systems consume approx. 545 mW of power. The system, which is designed for filter implementation in C language, uses 65% of all logical elements and consumes 729 mW of power.Article in Lithuanian

  11. Heterodyne Interferometer Angle Metrology

    Science.gov (United States)

    Hahn, Inseob; Weilert, Mark A.; Wang, Xu; Goullioud, Renaud

    2010-01-01

    A compact, high-resolution angle measurement instrument has been developed that is based on a heterodyne interferometer. The common-path heterodyne interferometer metrology is used to measure displacements of a reflective target surface. In the interferometer setup, an optical mask is used to sample the measurement laser beam reflecting back from a target surface. Angular rotations, around two orthogonal axes in a plane perpendicular to the measurement- beam propagation direction, are determined simultaneously from the relative displacement measurement of the target surface. The device is used in a tracking telescope system where pitch and yaw measurements of a flat mirror were simultaneously performed with a sensitivity of 0.1 nrad, per second, and a measuring range of 0.15 mrad at a working distance of an order of a meter. The nonlinearity of the device is also measured less than one percent over the measurement range.

  12. Optical sound wave recording by digital holography with heterodyne technique

    Science.gov (United States)

    Quan, Xiangyu; Rajput, Sudheesh; Nitta, Kouichi; Matoba, Osamu; Awatsuji, Yasuhiro

    2017-06-01

    A visualization technique of sound wave propagation using digital holography with heterodyne technique is presented. In the proposed method, the frequency of the interference pattern in an off-axis digital holography is down converted into the detectable frequency in an image sensor operated at the video frame rate by using the heterodyne interferometer. We present the principle of the recording technique and experimental results are described.

  13. Two-dimensional random arrays for real time volumetric imaging

    DEFF Research Database (Denmark)

    Davidsen, Richard E.; Jensen, Jørgen Arendt; Smith, Stephen W.

    1994-01-01

    beams. A random array with Gaussian distribution of transmitters and uniform distribution of receivers was found to have better resolution and depth-of-field than both a Mills cross array and a random array with uniform distribution of both transmit and receive elements. The Gaussian random array......Two-dimensional arrays are necessary for a variety of ultrasonic imaging techniques, including elevation focusing, 2-D phase aberration correction, and real time volumetric imaging. In order to reduce system cost and complexity, sparse 2-D arrays have been considered with element geometries...... selected ad hoc, by algorithm, or by random process. Two random sparse array geometries and a sparse array with a Mills cross receive pattern were simulated and compared to a fully sampled aperture with the same overall dimensions. The sparse arrays were designed to the constraints of the Duke University...

  14. Toroidal sensor arrays for real-time photoacoustic imaging

    Science.gov (United States)

    Bychkov, Anton S.; Cherepetskaya, Elena B.; Karabutov, Alexander A.; Makarov, Vladimir A.

    2017-07-01

    This article addresses theoretical and numerical investigation of image formation in photoacoustic (PA) imaging with complex-shaped concave sensor arrays. The spatial resolution and the size of sensitivity region of PA and laser ultrasonic (LU) imaging systems are assessed using sensitivity maps and spatial resolution maps in the image plane. This paper also discusses the relationship between the size of high-sensitivity regions and the spatial resolution of real-time imaging systems utilizing toroidal arrays. It is shown that the use of arrays with toroidal geometry significantly improves the diagnostic capabilities of PA and LU imaging to investigate biological objects, rocks, and composite materials.

  15. Toroidal sensor arrays for real-time photoacoustic imaging.

    Science.gov (United States)

    Bychkov, Anton S; Cherepetskaya, Elena B; Karabutov, Alexander A; Makarov, Vladimir A

    2017-07-01

    This article addresses theoretical and numerical investigation of image formation in photoacoustic (PA) imaging with complex-shaped concave sensor arrays. The spatial resolution and the size of sensitivity region of PA and laser ultrasonic (LU) imaging systems are assessed using sensitivity maps and spatial resolution maps in the image plane. This paper also discusses the relationship between the size of high-sensitivity regions and the spatial resolution of real-time imaging systems utilizing toroidal arrays. It is shown that the use of arrays with toroidal geometry significantly improves the diagnostic capabilities of PA and LU imaging to investigate biological objects, rocks, and composite materials.

  16. Compact heterodyne NEMS oscillator for sensing applications

    Science.gov (United States)

    Sansa, Marc; Gourlat, Guillaume; Jourdan, Guillaume; Gely, Marc; Villard, Patrick; Sicard, Gilles; Hentz, Sébastien

    2016-11-01

    We present a novel topology of heterodyne nanoelectromechanical self-oscillator, aimed at the dense integration of resonator arrays for sensing applications. This oscillator is based on an original measurement method, suitable for both open loop and closed loop operations, which simplifies current down-mixing set-ups. When implemented on-chip, it will allow the reduction of the size and power consumption of readout CMOS circuitry. This is today the limiting factor for the integration density of NEMS oscillators for real-life applications. Here we characterize this method in both open-loop and closed-loop, and evaluate its frequency stability.

  17. Vertically integrated thin film color sensor arrays for imaging applications.

    Science.gov (United States)

    Knipp, Dietmar; Street, Robert A; Stiebig, Helmut; Krause, Mathias; Lu, Jeng-Ping; Ready, Steve; Ho, Jackson

    2006-04-17

    Large area color sensor arrays based on vertically integrated thin-film sensors were realized. The complete color information of each color pixel is detected at the same position of the sensor array without using optical filters. The sensor arrays consist of amorphous silicon thin film color sensors integrated on top of amorphous silicon readout transistors. The spectral sensitivity of the sensors is controlled by the applied bias voltage. The operating principle of the color sensor arrays is described. Furthermore, the image quality and the pixel cross talk of the sensor arrays is analyzed by measurements of the line spread function and the modulation transfer function.

  18. Photonic Doppler velocimetry lens array probe incorporating stereo imaging

    Science.gov (United States)

    Malone, Robert M.; Kaufman, Morris I.

    2015-09-01

    A probe including a multiple lens array is disclosed to measure velocity distribution of a moving surface along many lines of sight. Laser light, directed to the moving surface is reflected back from the surface and is Doppler shifted, collected into the array, and then directed to detection equipment through optic fibers. The received light is mixed with reference laser light and using photonic Doppler velocimetry, a continuous time record of the surface movement is obtained. An array of single-mode optical fibers provides an optic signal to the multiple lens array. Numerous fibers in a fiber array project numerous rays to establish many measurement points at numerous different locations. One or more lens groups may be replaced with imaging lenses so a stereo image of the moving surface can be recorded. Imaging a portion of the surface during initial travel can determine whether the surface is breaking up.

  19. Differential doppler heterodyning technique

    DEFF Research Database (Denmark)

    Lading, Lars

    1971-01-01

    Measuring velocity without disturbing the moving object is possible by use of the laser doppler heterodyning technique. Theoretical considerations on the doppler shift show that the antenna property of the photodetector can solve an apparent conflict between two different ways of calculating...... the detected doppler frequency. It is found that the doppler frequency for this particular setup is independent of the direction of detection. Investigations of the signal-to-noise ratio (SNR) show that the maximum SNR-considering the optical setup-is obtained by measuring the frequency difference between two...... doppler-shifted beams rather than by measuring the shift of a single beam by comparing it with a reference beam. Measurements seem to be in agreement with the theoretical consideration...

  20. Vision communications based on LED array and imaging sensor

    Science.gov (United States)

    Yoo, Jong-Ho; Jung, Sung-Yoon

    2012-11-01

    In this paper, we propose a brand new communication concept, called as "vision communication" based on LED array and image sensor. This system consists of LED array as a transmitter and digital device which include image sensor such as CCD and CMOS as receiver. In order to transmit data, the proposed communication scheme simultaneously uses the digital image processing and optical wireless communication scheme. Therefore, the cognitive communication scheme is possible with the help of recognition techniques used in vision system. By increasing data rate, our scheme can use LED array consisting of several multi-spectral LEDs. Because arranged each LED can emit multi-spectral optical signal such as visible, infrared and ultraviolet light, the increase of data rate is possible similar to WDM and MIMO skills used in traditional optical and wireless communications. In addition, this multi-spectral capability also makes it possible to avoid the optical noises in communication environment. In our vision communication scheme, the data packet is composed of Sync. data and information data. Sync. data is used to detect the transmitter area and calibrate the distorted image snapshots obtained by image sensor. By making the optical rate of LED array be same with the frame rate (frames per second) of image sensor, we can decode the information data included in each image snapshot based on image processing and optical wireless communication techniques. Through experiment based on practical test bed system, we confirm the feasibility of the proposed vision communications based on LED array and image sensor.

  1. Rad Hard Imaging Array with Picosecond Timing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For a wide range of remote sensing applications, there is a critical need to develop imaging arrays that simultaneously achieve high spatial resolution, high...

  2. Sparse acoustic imaging with a spherical array

    DEFF Research Database (Denmark)

    Fernandez Grande, Efren; Xenaki, Angeliki

    2015-01-01

    In recent years, a number of methods for sound source localization and sound field reconstruction with spherical microphone arrays have been proposed. These arrays have properties that are potentially very useful, e.g. omni-directionality, robustness, compensable scattering, etc. This paper...... proposes a plane wave expansion method based on measurements with a spherical microphone array, and solved in the framework provided by Compressed Sensing. The proposed methodology results in a sparse solution, i.e. few non-zero coefficients, and it is suitable for both source localization and sound field...... reconstruction. In general it provides fine spatial resolution for localization (delta-like functions), and robust reconstruction (the noisy components are naturally suppressed). The validity and performance of the proposed method is examined, and its limitations as well as the underlying assumptions...

  3. 7T Human Spine Imaging Arrays With Adjustable Inductive Decoupling

    Science.gov (United States)

    Wu, Bing; Wang, Chunsheng; Krug, Roland; Kelley, Douglas A.; Xu, Duan; Pang, Yong; Banerjee, Suchandrima; Vigneron, Daniel B.; Nelson, Sarah J.; Majumdar, Sharmila

    2010-01-01

    Ultrahigh-field human spine RF transceiver coil arrays face daunting technical challenges in achieving large imaging coverage with sufficient B1 penetration and sensitivity, and in attaining robust decoupling among coil elements. In this paper, human spine coil arrays for ultrahigh field were built and studied. Transceiver arrays with loop-shaped microstrip transmission line were designed, fabricated, and tested for 7-tesla (7T)MRI. With the proposed adjustable inductive decoupling technique, the isolation between adjacent coil elements is easily addressed. Preliminary results of human spine images acquired using the transceiver arrays demonstrate the feasibility of the design for ultrahigh-field MR applications and its robust performance for parallel imaging. PMID:19709956

  4. Highspeed multiplexed heterodyne interferometry.

    Science.gov (United States)

    Isleif, Katharina-S; Gerberding, Oliver; Köhlenbeck, Sina; Sutton, Andrew; Sheard, Benjamin; Goßler, Stefan; Shaddock, Daniel; Heinzel, Gerhard; Danzmann, Karsten

    2014-10-06

    Digitally enhanced heterodyne interferometry is a metrology technique that uses pseudo-random noise codes for modulating the phase of the laser light. Multiple interferometric signals from the same beam path can thereby be isolated based on their propagation delay, allowing one to use advantageous optical layouts in comparison to classic laser interferometers. We present here a high speed version of this technique for measuring multiple targets spatially separated by only a few centimetres. This allows measurements of multiplexed signals using free beams, making the technique attractive for several applications requiring compact optical set-ups like for example space-based interferometers. In an experiment using a modulation and sampling rate of 1.25 GHz we are able to demonstrate multiplexing between targets only separated by 36 cm and we achieve a displacement measurement noise floor of up. Utilising an active clock jitter correction scheme we are also able to reduce this noise in a null measurement configuration by one order of magnitude.

  5. In-vivo evaluation of convex array synthetic aperture imaging

    DEFF Research Database (Denmark)

    Pedersen, Morten Høgholm; Gammelmark, Kim Løkke; Jensen, Jørgen Arendt

    2007-01-01

    resolution, contrast resolution, and artifacts. Acquisition was performed using our research scanner RASMUS and a 5.5 MHz convex array transducer. STA imaging was acquired using circular wave emulation by 33-element subapertures and a 20 us linear FM signal as excitation pulse. For conventional imaging a 64...

  6. Multi beam imaging array based on leaky lens antennas

    NARCIS (Netherlands)

    Bruni, S.; Neto, A.; Gerini, G.; Bekers, D.J.

    2007-01-01

    This paper proposes a novel imaging architecture suited for use in the mm and the submm wave regimes. The structure is composed by a one dimensional array of radiators in order to enhance the image acquisition time with respect to single element detection. Moreover each of the antenna elements

  7. In-vivo Convex Array Vector Flow Imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Brandt, Andreas Hjelm; Nielsen, Michael Bachmann

    2014-01-01

    . For this volunteer the duration corresponded to roughly 3 heartbeats. The velocities were found at a beam-to-flow angle of 72 21, where a conventional CFM scan would yield poor results. Three VF images from the same position in the cardiac cycle were investigated and the mean lateral velocities were -0.079, -0......In-vivo VFI scans obtained from the abdomen of a human volunteer using a convex array transducers and trans- verse oscillation vector flow imaging (VFI) are presented. A 3 MHz BK Medical 8820e (Herlev, Denmark) 192-element convex array probe is used with the SARUS experimental ultrasound scanner...

  8. Adaptive-array Electron Cyclotron Emission diagnostics using data streaming in a Software Defined Radio system

    Science.gov (United States)

    Idei, H.; Mishra, K.; Yamamoto, M. K.; Hamasaki, M.; Fujisawa, A.; Nagashima, Y.; Hayashi, Y.; Onchi, T.; Hanada, K.; Zushi, H.; the QUEST Team

    2016-04-01

    Measurement of the Electron Cyclotron Emission (ECE) spectrum is one of the most popular electron temperature diagnostics in nuclear fusion plasma research. A 2-dimensional ECE imaging system was developed with an adaptive-array approach. A radio-frequency (RF) heterodyne detection system with Software Defined Radio (SDR) devices and a phased-array receiver antenna was used to measure the phase and amplitude of the ECE wave. The SDR heterodyne system could continuously measure the phase and amplitude with sufficient accuracy and time resolution while the previous digitizer system could only acquire data at specific times. Robust streaming phase measurements for adaptive-arrayed continuous ECE diagnostics were demonstrated using Fast Fourier Transform (FFT) analysis with the SDR system. The emission field pattern was reconstructed using adaptive-array analysis. The reconstructed profiles were discussed using profiles calculated from coherent single-frequency radiation from the phase array antenna.

  9. High-frequency ultrasonic arrays for ocular imaging

    Science.gov (United States)

    Jaeger, M. D.; Kline-Schoder, R. J.; Douville, G. M.; Gagne, J. R.; Morrison, K. T.; Audette, W. E.; Kynor, D. B.

    2007-03-01

    High-resolution ultrasound imaging of the anterior portion of the eye has been shown to provide important information for sizing of intraocular lens implants, diagnosis of pathological conditions, and creation of detailed maps of corneal topography to guide refractive surgery. Current ultrasound imaging systems rely on mechanical scanning of a single acoustic element over the surface of the eye to create the three-dimensional information needed by clinicians. This mechanical scanning process is time-consuming and subject to errors caused by eye movement during the scanning period. This paper describes development of linear ultrasound imaging arrays intended to increase the speed of image acquisition and reduce problems associated with ocular motion. The arrays consist of a linear arrangement of high-frequency transducer elements designed to operate in the 50 - 75 MHz frequency range. The arrays are produced using single-crystal lithium niobate piezoelectric material, thin film electrodes, and epoxy-based acoustic layers. The array elements have been used to image steel test structures and bovine cornea.

  10. Simulated electronic heterodyne recording and processing of pulsed-laser holograms

    Science.gov (United States)

    Decker, A. J.

    1979-01-01

    The electronic recording of pulsed-laser holograms is proposed. The polarization sensitivity of each resolution element of the detector is controlled independently to add an arbitrary phase to the image waves. This method which can be used to simulate heterodyne recording and to process three-dimensional optical images, is based on a similar method for heterodyne recording and processing of continuous-wave holograms.

  11. Code-modulated interferometric imaging system using phased arrays

    Science.gov (United States)

    Chauhan, Vikas; Greene, Kevin; Floyd, Brian

    2016-05-01

    Millimeter-wave (mm-wave) imaging provides compelling capabilities for security screening, navigation, and bio- medical applications. Traditional scanned or focal-plane mm-wave imagers are bulky and costly. In contrast, phased-array hardware developed for mass-market wireless communications and automotive radar promise to be extremely low cost. In this work, we present techniques which can allow low-cost phased-array receivers to be reconfigured or re-purposed as interferometric imagers, removing the need for custom hardware and thereby reducing cost. Since traditional phased arrays power combine incoming signals prior to digitization, orthogonal code-modulation is applied to each incoming signal using phase shifters within each front-end and two-bit codes. These code-modulated signals can then be combined and processed coherently through a shared hardware path. Once digitized, visibility functions can be recovered through squaring and code-demultiplexing operations. Pro- vided that codes are selected such that the product of two orthogonal codes is a third unique and orthogonal code, it is possible to demultiplex complex visibility functions directly. As such, the proposed system modulates incoming signals but demodulates desired correlations. In this work, we present the operation of the system, a validation of its operation using behavioral models of a traditional phased array, and a benchmarking of the code-modulated interferometer against traditional interferometer and focal-plane arrays.

  12. ISPA (imaging silicon pixel array) experiment

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    The ISPA tube is a position-sensitive photon detector. It belongs to the family of hybrid photon detectors (HPD), recently developed by CERN and INFN with leading photodetector firms. HPDs confront in a vacuum envelope a photocathode and a silicon detector. This can be a single diode or a pixelized detector. The electrons generated by the photocathode are efficiently detected by the silicon anode by applying a high-voltage difference between them. ISPA tube can be used in high-energy applications as well as bio-medical and imaging applications.

  13. Coded aperture subreflector array for high resolution radar imaging

    Science.gov (United States)

    Lynch, Jonathan J.; Herrault, Florian; Kona, Keerti; Virbila, Gabriel; McGuire, Chuck; Wetzel, Mike; Fung, Helen; Prophet, Eric

    2017-05-01

    HRL Laboratories has been developing a new approach for high resolution radar imaging on stationary platforms. High angular resolution is achieved by operating at 235 GHz and using a scalable tile phased array architecture that has the potential to realize thousands of elements at an affordable cost. HRL utilizes aperture coding techniques to minimize the size and complexity of the RF electronics needed for beamforming, and wafer level fabrication and integration allow tiles containing 1024 elements to be manufactured with reasonable costs. This paper describes the results of an initial feasibility study for HRL's Coded Aperture Subreflector Array (CASA) approach for a 1024 element micromachined antenna array with integrated single-bit phase shifters. Two candidate electronic device technologies were evaluated over the 170 - 260 GHz range, GaN HEMT transistors and GaAs Schottky diodes. Array structures utilizing silicon micromachining and die bonding were evaluated for etch and alignment accuracy. Finally, the overall array efficiency was estimated to be about 37% (not including spillover losses) using full wave array simulations and measured device performance, which is a reasonable value at 235 GHz. Based on the measured data we selected GaN HEMT devices operated passively with 0V drain bias due to their extremely low DC power dissipation.

  14. Rice8987 Array: Gel images - RMOS | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available List Contact us RMOS Rice8987 Array: Gel images Data detail Data name Rice8987 Array: Gel images DOI 10.1890...e by Wako), was used to other Dplate. Gel images were scanned by scanner (Molecular Dynamics Co.). Number of...Database Site Policy | Contact Us Rice8987 Array: Gel images - RMOS | LSDB Archive ...

  15. Nano-fabricated pixelated micropolarizer array for visible imaging polarimetry.

    Science.gov (United States)

    Zhang, Zhigang; Dong, Fengliang; Cheng, Teng; Qiu, Kang; Zhang, Qingchuan; Chu, Weiguo; Wu, Xiaoping

    2014-10-01

    Pixelated micropolarizer array (PMA) is a novel concept for real-time visible imaging polarimetry. A 320 × 240 aluminum PMA fabricated by electron beam lithography is described in this paper. The period, duty ratio, and depth of the grating are 140 nm, 0.5, and 100 nm, respectively. The units are standard square structures and the metal nanowires of the grating are collimating and uniformly thick. The extinction ratio of 75 and the maximum polarization transmittance of 78.8% demonstrate that the PMA is suitable for polarization imaging. When the PMA is applied to real-time polarization imaging, the degree of linear polarization image and the angle of linear polarization image are calculated from a single frame image. The polarized target object is highlighted from the unpolarized background, and the surface contour of the target object can be reflected by the polarization angle.

  16. Selenium coated CMOS passive pixel array for medical imaging

    Science.gov (United States)

    Majid, Shaikh Hasibul; Goldan, Amir H.; Hadji, Bahman; Belev, George; Kasap, Safa; Karim, Karim S.

    2011-03-01

    Digital imaging systems for medical applications use amorphous silicon thin-film transistor (TFT) technology due to its ability to be manufactured over large areas. However, TFT technology is far inferior to crystalline silicon CMOS technology in terms of the speed, stability, noise susceptibility, and feature size. This work investigates the feasibility of integrating an imaging array fabricated in CMOS technology with an a-Se detector. The design of a CMOS passive pixel sensor (PPS) array is presented, in addition to how an 8×8 PPS array is integrated with the 75 micron thick stabilized amorphous selenium detector. A non-linear increase in the dark current of 200 pA, 500 pA and 2 nA is observed with 0.27, 0.67 and 1.33 V/micron electric field respectively, which shows a successful integration of selenium layer with the CMOS array. Results also show that the integrated Selenium-CMOS PPS array has good responsivity to optical light and X-rays, leaving the door open for further research on implementing CMOS imaging architectures going forward. Demonstrating that the PPS chips using CMOS technology can use a-Se as a detector is thus the first step in a promising path of research, which should yield substantial and exciting results for the field. Though area may still prove challenging, larger CMOS wafers can be manufactured and tiled to allow for a large enough size for certain diagnostic imaging applications and potentially even large area applications like digital mammography.

  17. Uncooled infrared focal plane array imaging in China

    Science.gov (United States)

    Lei, Shuyu

    2015-06-01

    This article reviews the development of uncooled infrared focal plane array (UIFPA) imaging in China in the past decade. Sensors based on optical or electrical read-out mechanism were developed but the latter dominates the market. In resistive bolometers, VOx and amorphous silicon are still the two major thermal-sensing materials. The specifications of the IRFPA made by different manufactures were collected and compared. Currently more than five Chinese companies and institutions design and fabricate uncooled infrared focal plane array. Some devices have sensitivity as high as 30 mK; the largest array for commercial products is 640×512 and the smallest pixel size is 17 μm. Emphasis is given on the pixel MEMS design, ROIC design, fabrication, and packaging of the IRFPA manufactured by GWIC, especially on design for high sensitivities, low noise, better uniformity and linearity, better stabilization for whole working temperature range, full-digital design, etc.

  18. Imaging and magnetotransport in superconductor/magnetic dot arrays

    Science.gov (United States)

    Silevitch, D. M.; Reich, D. H.; Chien, C. L.; Field, S. B.; Shtrikman, H.

    2001-06-01

    Magnetoresistance and scanning Hall probe microscopy studies of Nb-film/Ni-dot structures are reported. The dots act as pinning sites for superconducting vortices. The transport measurements focus on the effects of introducing disorder into the positions of the pinning lattice near the superconducting critical temperature Tc in structures with 250 nm diameter Ni dots randomized about an ideal square lattice with lattice constant a=560 nm. Features observable in the ordered arrays at higher multiples of the matching field H0=Φ0/a2 are washed out in the disordered arrays, but those at H0 remain. Scanning Hall probe microscope images were taken of the vortex configurations at fields up to 1.2H0 in ordered arrays of 1-μm-diameter dots on a 5.2 μm×4 μm rectangular lattice. These show that despite the relatively weak pinning of the magnetic dots, ordering commensurate with the dot lattice occurs even for fields below H0. Both transport and imaging studies point to the importance of interstitial vortices in determining the properties of superconductor/magnetic dot arrays.

  19. Monitoring fatigue crack growth using nonlinear ultrasonic phased array imaging

    Science.gov (United States)

    Cheng, Jingwei; Potter, Jack N.; Croxford, Anthony J.; Drinkwater, Bruce W.

    2017-05-01

    Nonlinear imaging techniques have recently emerged which have the potential to detect material degradation and challenging defects, such as closed cracks. This paper describes an investigation into the performance of nonlinear ultrasonic imaging (NUI) for the monitoring of the early stages of fatigue crack growth. This technique, in conjunction with conventional array imaging, is applied to the periodic monitoring of steel compact tension specimens subjected to high cycle fatigue loading. The detection limits of these techniques are investigated. Their abilities to localise and detect small cracks are further quantified with the aid of micrography. The results suggest that NUI is more sensitive than conventional ultrasonic imaging to the microscale changes occurring at the early stages of failure, i.e. detectability starts c. 15% of fatigue life. In addition to early detection, the potential for NUI to deliver accurate sizing of fatigue cracks and monitor crack propagation is also presented.

  20. Least-Squares Estimation of Imaging Parameters for an Ultrasonic Array Using Known Geometric Image Features

    NARCIS (Netherlands)

    Hunter, A.J.; Drinkwater, B.W.; Wilcox, P.D.

    2011-01-01

    Ultrasonic array images are adversely affected by errors in the assumed or measured imaging parameters. For non-destructive testing and evaluation, this can result in reduced defect detection and characterization performance. In this paper, an autofocus algorithm is presented for estimating and

  1. Broadband image sensor array based on graphene-CMOS integration

    Science.gov (United States)

    Goossens, Stijn; Navickaite, Gabriele; Monasterio, Carles; Gupta, Shuchi; Piqueras, Juan José; Pérez, Raúl; Burwell, Gregory; Nikitskiy, Ivan; Lasanta, Tania; Galán, Teresa; Puma, Eric; Centeno, Alba; Pesquera, Amaia; Zurutuza, Amaia; Konstantatos, Gerasimos; Koppens, Frank

    2017-06-01

    Integrated circuits based on complementary metal-oxide-semiconductors (CMOS) are at the heart of the technological revolution of the past 40 years, enabling compact and low-cost microelectronic circuits and imaging systems. However, the diversification of this platform into applications other than microcircuits and visible-light cameras has been impeded by the difficulty to combine semiconductors other than silicon with CMOS. Here, we report the monolithic integration of a CMOS integrated circuit with graphene, operating as a high-mobility phototransistor. We demonstrate a high-resolution, broadband image sensor and operate it as a digital camera that is sensitive to ultraviolet, visible and infrared light (300-2,000 nm). The demonstrated graphene-CMOS integration is pivotal for incorporating 2D materials into the next-generation microelectronics, sensor arrays, low-power integrated photonics and CMOS imaging systems covering visible, infrared and terahertz frequencies.

  2. Improvements on Fresnel arrays for high contrast imaging

    Science.gov (United States)

    Wilhem, Roux; Laurent, Koechlin

    2018-01-01

    The Fresnel Diffractive Array Imager (FDAI) is based on a new optical concept for space telescopes, developed at Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France. For the visible and near-infrared it has already proven its performances in resolution and dynamic range. We propose it now for astrophysical applications in the ultraviolet with apertures from 6 to 30 meters, aimed at imaging in UV faint astrophysical sources close to bright ones, as well as other applications requiring high dynamic range. Of course the project needs first a probatory mission at small aperture to validate the concept in space. In collaboration with institutes in Spain and Russia, we will propose to board a small prototype of Fresnel imager on the International Space Station (ISS), with a program combining technical tests and astrophysical targets. The spectral domain should contain the Lyman-α line (λ = 121 nm). As part of its preparation, we improve the Fresnel array design for a better Point Spread Function in UV, presently on a small laboratory prototype working at 260 nm. Moreover, we plan to validate a new optical design and chromatic correction adapted to UV. In this article we present the results of numerical propagations showing the improvement in dynamic range obtained by combining and adapting three methods : central obturation, optimization of the bars mesh holding the Fresnel rings, and orthogonal apodization. We briefly present the proposed astrophysical program of a probatory mission with such UV optics.

  3. Microfabricated optically pumped magnetometer arrays for biomedical imaging

    Science.gov (United States)

    Perry, A. R.; Sheng, D.; Krzyzewski, S. P.; Geller, S.; Knappe, S.

    2017-02-01

    Optically-pumped magnetometers have demonstrated magnetic field measurements as precise as the best superconducting quantum interference device magnetometers. Our group develops miniature alkali atom-based magnetic sensors using microfabrication technology. Our sensors do not require cryogenic cooling, and can be positioned very close to the sample, making these sensors an attractive option for development in the medical community. We will present our latest chip-scale optically-pumped gradiometer developed for array applications to image magnetic fields from the brain noninvasively. These developments should lead to improved spatial resolution, and potentially sensitive measurements in unshielded environments.

  4. Ultrasonic phased array with surface acoustic wave for imaging cracks

    Directory of Open Access Journals (Sweden)

    Yoshikazu Ohara

    2017-06-01

    Full Text Available To accurately measure crack lengths, we developed a real-time surface imaging method (SAW PA combining an ultrasonic phased array (PA with a surface acoustic wave (SAW. SAW PA using a Rayleigh wave with a high sensitivity to surface defects was implemented for contact testing using a wedge with the third critical angle that allows the Rayleigh wave to be generated. Here, to realize high sensitivity imaging, SAW PA was optimized in terms of the wedge and the imaging area. The improved SAW PA was experimentally demonstrated using a fatigue crack specimen made of an aluminum alloy. For further verification in more realistic specimens, SAW PA was applied to stainless-steel specimens with a fatigue crack and stress corrosion cracks (SCCs. The fatigue crack was visualized with a high signal-to-noise ratio (SNR and its length was measured with a high accuracy of better than 1 mm. The SCCs generated in the heat-affected zones (HAZs of a weld were successfully visualized with a satisfactory SNR, although responses at coarse grains appeared throughout the imaging area. The SCC lengths were accurately measured. The imaging results also precisely showed complicated distributions of SCCs, which were in excellent agreement with the optically observed distributions.

  5. Characteristics of Monolithically Integrated InGaAs Active Pixel Image Array

    Science.gov (United States)

    Kim, Q.; Cunningham, T. J.; Pain, B.; Lange, M. J.; Olsen, G. H.

    1999-01-01

    Switching and amplifying characteristics of a newly developed monolithic InGaAs Active Pixel Imager Array are presented. The sensor array is fabricated from InGaAs material epitaxially deposited on an InP substrate.

  6. High-resolution imaging methods in array signal processing

    DEFF Research Database (Denmark)

    Xenaki, Angeliki

    The purpose of this study is to develop methods in array signal processing which achieve accurate signal reconstruction from limited observations resulting in high-resolution imaging. The focus is on underwater acoustic applications and sonar signal processing both in active (transmit and receive...... in active sonar signal processing for detection and imaging of submerged oil contamination in sea water from a deep-water oil leak. The submerged oil _eld is modeled as a uid medium exhibiting spatial perturbations in the acoustic parameters from their mean ambient values which cause weak scattering......-of-arrival (DOA) of the associated wavefronts from a limited number of observations. Usually, there are only a few sources generating the acoustic wavefield such that DOA estimation is essentially a sparse signal reconstruction problem. Conventional methods for DOA estimation (i.e., beamforming) suffer from...

  7. Prototype amorphous silicon array based radiotherapy portal imager

    Science.gov (United States)

    Drake, Douglas G.; Jaffray, David A.; Wong, John W.

    1997-05-01

    The trend toward highly conformal radiation fields in the treatment of cancer has increased the need for accurate verification of field placement.Conventionally, the placement has ben verified on a weekly basis using a film radiograph, or more recently electronic portal imaging devices (EPIDs). Fluoroscopic EPIDs consisting of a phosphor screen, one or more mirrors, lens, and camera provide reasonable performance but suffer from the poor collection efficiency and bulky nature of their optical components. Large area a-Si:H arrays provide an ideal replacement for the optical subsystem of fluoroscopic EPIDs. The purpose of this work is to (1) characterize the performance and logistics of a prototype a-Si:H array and (2) determine the metal plate/phosphor screen combination which will maximize the system's detective quantum efficiency (DQE) for megavoltage imaging. The prototype imager is based on a 10 X 10 cm2 a-Si:H array consisting of 128 X 128 sensor elements coupled to a Gd2O2S:Tb screen and 0.5 mm Al plate. The charge signal collected in each diode is digitized to 16 bits at frame rates of up to 25 frames/sec. Dark current and readout noise were determined under controlled conditions. The optical collection efficiency of the photodiodes and the escape fraction of optical quanta from the screen were estimated from the literature. X-ray quantum absorption efficiency, number of optical quanta from the screen were estimated from the literature. X-ray quantum absorption efficiency, number of optical quanta produced, and the Poisson excess associated with energy absorption and conversion in the plate/screen system were calculated using EGS4 Monte Carlo simulations. Using these results, the imaging system performance is estimated using the approach of Cunningham et al for both a 6 MV x-ray spectrum and a 60Co spectrum. For both the 6 MV and 60Co beams, the predicted system gain was approximately 60 percent of the measured value. For a 6 MV beam, the system DQE (f equals

  8. Anomaly effects of arrays for 3d geoelectrical resistivity imaging ...

    African Journals Online (AJOL)

    The anomaly effects observed in dipole-dipole (DDP), pole-dipole (PDP) and Wenner-Schlumberger (WSC) arrays were generally larger than that observed in other arrays considered. The least anomaly effect on the synthetic models was observed in pole-pole (PP) array. This indicates that DDP, PDP and WSC arrays are ...

  9. Multichannel Double-Row Transmission Line Array for Human MR Imaging at Ultrahigh Fields.

    Science.gov (United States)

    Yan, Xinqiang; Pedersen, Jan Ole; Wei, Long; Zhang, Xiaoliang; Xue, Rong

    2015-06-01

    In microstrip transmission line (MTL) transmit/receive (transceive) arrays used for ultrahigh field MRI, the array length is often constrained by the required resonant frequency, limiting the image coverage. The purpose of this study is to increase the imaging coverage and also improve its parallel imaging capability by utilizing a double-row design. A 16-channel double-row MTL transceive array was designed, constructed, and tested for human head imaging at 7 T. Array elements between two rows were decoupled by using the induced current elimination or magnetic wall decoupling technique. In vivo human head images were acquired, and g-factor results were calculated to evaluate the performance of this double-row array. Testing results showed that all coil elements were well decoupled with a better than -18 dB transmission coefficient between any two elements. The double-row array improves the imaging quality of the lower portion of the human head, and has low g-factors even at high acceleration rates. Compared with a regular single-row MTL array, the double-row array demonstrated a larger imaging coverage along the z-direction with improved parallel imaging capability. The proposed technique is particularly suitable for the design of large-sized transceive arrays with large channel counts, which ultimately benefits the imaging performance in human MRI.

  10. Photon-Counting Arrays for Time-Resolved Imaging

    Directory of Open Access Journals (Sweden)

    I. Michel Antolovic

    2016-06-01

    Full Text Available The paper presents a camera comprising 512 × 128 pixels capable of single-photon detection and gating with a maximum frame rate of 156 kfps. The photon capture is performed through a gated single-photon avalanche diode that generates a digital pulse upon photon detection and through a digital one-bit counter. Gray levels are obtained through multiple counting and accumulation, while time-resolved imaging is achieved through a 4-ns gating window controlled with subnanosecond accuracy by a field-programmable gate array. The sensor, which is equipped with microlenses to enhance its effective fill factor, was electro-optically characterized in terms of sensitivity and uniformity. Several examples of capture of fast events are shown to demonstrate the suitability of the approach.

  11. Transverse Oscillations for Phased Array Vector Velocity Imaging

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Jensen, Jørgen Arendt

    2010-01-01

    of superficial blood vessels. To broaden the usability of the method, it should be expanded to a phased array geometry enabling vector velocity imaging of the heart. Therefore, the scan depth has to be increased to 10-15 cm. This paper presents suitable pulse echo fields (PEF). Two lines are beamformed...... in receive to obtain lateral spatial in-phase and quadrature components. The relative mean bias and standard deviation of the lateral velocity component are computed as performance measures. For the PEF, the coefficient of variance, CV, of the spectral frequencies, and the energy ratio, ER, of leakage...... into negative frequencies are used as metrics to assess estimator performance. At 10 cm’s depth for an initial setup, the relative mean bias and standard deviation are 9.1% and 9.5%, respectively. At a depth of 15 cm, the values are 20% and 13%, respectively. The PEF metric ER can be used to assess the bias...

  12. CMOS nanoelectrode array for all-electrical intracellular electrophysiological imaging

    Science.gov (United States)

    Abbott, Jeffrey; Ye, Tianyang; Qin, Ling; Jorgolli, Marsela; Gertner, Rona S.; Ham, Donhee; Park, Hongkun

    2017-05-01

    Developing a new tool capable of high-precision electrophysiological recording of a large network of electrogenic cells has long been an outstanding challenge in neurobiology and cardiology. Here, we combine nanoscale intracellular electrodes with complementary metal-oxide-semiconductor (CMOS) integrated circuits to realize a high-fidelity all-electrical electrophysiological imager for parallel intracellular recording at the network level. Our CMOS nanoelectrode array has 1,024 recording/stimulation 'pixels' equipped with vertical nanoelectrodes, and can simultaneously record intracellular membrane potentials from hundreds of connected in vitro neonatal rat ventricular cardiomyocytes. We demonstrate that this network-level intracellular recording capability can be used to examine the effect of pharmaceuticals on the delicate dynamics of a cardiomyocyte network, thus opening up new opportunities in tissue-based pharmacological screening for cardiac and neuronal diseases as well as fundamental studies of electrogenic cells and their networks.

  13. Using Phased Array for Transverse Oscillation Vector Velocity Imaging

    DEFF Research Database (Denmark)

    Pihl, Michael Johannes; Haugaard, Per; Jensen, Jørgen Arendt

    be expanded to phased arrays enabling vector velocity imaging of the heart. Therefore, the performance of the TO estimator has to be evaluated for depths up to 10-15 cm. Methods The TO method is based on creating a double oscillating field. Flow phantoms were simulated with a transverse (90º) parabolic flow...... realizations. Results With a F-number of 10 in transmit and receive peaks (spaced 96 elements apart) shaped as Hanning functions, parabolic velocity profiles were be observed for all cases. At depths of 10, 12, and 15 cm, the following results were obtained in pairs of σr & Br: 6.5% & 2.6%, 7.5% & 3.8%, and 8...

  14. Time-Domain Fluorescence Lifetime Imaging Techniques Suitable for Solid-State Imaging Sensor Arrays

    Directory of Open Access Journals (Sweden)

    Robert K. Henderson

    2012-05-01

    Full Text Available We have successfully demonstrated video-rate CMOS single-photon avalanche diode (SPAD-based cameras for fluorescence lifetime imaging microscopy (FLIM by applying innovative FLIM algorithms. We also review and compare several time-domain techniques and solid-state FLIM systems, and adapt the proposed algorithms for massive CMOS SPAD-based arrays and hardware implementations. The theoretical error equations are derived and their performances are demonstrated on the data obtained from 0.13 μm CMOS SPAD arrays and the multiple-decay data obtained from scanning PMT systems. In vivo two photon fluorescence lifetime imaging data of FITC-albumin labeled vasculature of a P22 rat carcinosarcoma (BD9 rat window chamber are used to test how different algorithms perform on bi-decay data. The proposed techniques are capable of producing lifetime images with enough contrast.

  15. Rectangle Surface Coil Array in a Grid Arrangement for Resonance Imaging

    Science.gov (United States)

    2016-02-13

    magnet wires with insulating coating for rectangular surface coils. The wires are formed into four one turn 145mm x 32mm rectangular coils...switchable array, RF magnetic field, NQR, MRI, NMR, tuning, decoupling I. INTRODUCTION ESONANCE imaging can be accomplished using Nuclear Magnetic ...grid array. This achieves the switchable array configuration. Later, investigations will have circuit controlled multiplexer for switching to

  16. Tilted microstrip phased arrays with improved electromagnetic decoupling for ultrahigh-field magnetic resonance imaging.

    Science.gov (United States)

    Pang, Yong; Wu, Bing; Jiang, Xiaohua; Vigneron, Daniel B; Zhang, Xiaoliang

    2014-12-01

    One of the technical challenges in designing a dedicated transceiver radio frequency (RF) array for MR imaging in humans at ultrahigh magnetic fields is how to effectively decouple the resonant elements of the array. In this work, we propose a new approach using tilted microstrip array elements for improving the decoupling performance and potentially parallel imaging capability. To investigate and validate the proposed design technique, an 8-channel volume array with tilted straight-type microstrip elements was designed, capable for human imaging at the ultrahigh field of 7 Tesla. In this volume transceiver array, its electromagnetic decoupling behavior among resonant elements, RF field penetration to biological samples, and parallel imaging performance were studied through bench tests and in vivo MR imaging experiments. In this specific tilted element array design, decoupling among array elements changes with the tilted angle of the elements and the best decoupling can be achieved at certain tilted angle. In vivo human knee MR images were acquired using the tilted volume array at 7 Tesla for method validation. Results of this study demonstrated that the electromagnetic decoupling between array elements and the B1 field strength can be improved by using the tilted element method in microstrip RF coil array designs at the ultrahigh field of 7T.

  17. Scanning array radar system for bridge subsurface imaging

    Science.gov (United States)

    Lai, Chieh-Ping; Ren, Yu-Jiun; Yu, Tzu Yang

    2012-04-01

    Early damage detection of bridge has been an important issue for modern civil engineering technique. Existing bridge inspection techniques used by State Department of Transportation (DOT) and County DOT include visual inspection, mechanical sounding, rebound hammer, cover meter, electrical potential measurements, and ultrasonics; other NDE techniques include ground penetrating radar (GPR), radiography, and some experimental types of sensors. Radar technology like GPR has been widely used for the bridge structure detection with a good penetration depth using microwave energy. The system to be presented in this paper is a different type of microwave sensing technology. It is focus on the subsurface detection and trying to find out detail information at subsurface (10 cm) with high resolution radar imaging from a flexible standoff distance. Our radar operating frequency is from 8-12 GHz, which is different from most of the current GPR systems. Scanning array antenna system is designed for adjustable beamwidth, preferable scanning area, and low sidelobe level. From the theoretical analysis and experimental results, it is found that the proposed technique can successfully capture the presence of the near-surface anomaly. This system is part of our Multi- Modal Remote Sensing System (MRSS) and provides good imaging correlations with other MRSS sensors.

  18. Resolution comparison between integral-imaging-based hologram synthesis methods using rectangular and hexagonal lens arrays.

    Science.gov (United States)

    Chen, Ni; Yeom, Jiwoon; Jung, Jae-Hyun; Park, Jae-Hyeung; Lee, Byoungho

    2011-12-19

    We compare the resolution of the hologram reconstruction synthesis methods based on integral imaging using rectangular and hexagonal lens arrays. By using a hexagonal lens array instead of conventional rectangular lens array, the three-dimensional objects are sampled with hexagonal grids. Due to more efficient sampling of the hexagonal grid, the resolution of the reconstructed object is higher compared with the case of using rectangular lens array. We analyze the resolution enhancement of the hologram reconstruction quantitatively and verify it experimentally.

  19. A Broadband and High Gain Tapered Slot Antenna for W-Band Imaging Array Applications

    Directory of Open Access Journals (Sweden)

    Dong Sik Woo

    2014-01-01

    Full Text Available A broadband and high gain tapered slot antenna (TSA by utilizing a broadband microstrip- (MS- to-coplanar stripline (CPS balun has been developed for millimeter-wave imaging systems and sensors. This antenna exhibits ultrawideband performance for frequency ranges from 70 to over 110 GHz with the high antenna gain, low sidelobe levels, and narrow beamwidth. The validity of this antenna as imaging arrays is also demonstrated by analyzing mutual couplings and 4-element linear array. This antenna can be applied to mm-wave phased array, imaging array for plasma diagnostics applications.

  20. MAGPIS: A MULTI-ARRAY GALACTIC PLANE IMAGING SURVEY

    Energy Technology Data Exchange (ETDEWEB)

    Helfand, D J; Becker, R H; White, R L; Fallon, A; Tuttle, S

    2005-11-10

    We present the Multi-Array Galactic Plane Imaging Survey (MAGPIS), which maps portions of the first Galactic quadrant with an angular resolution, sensitivity and dynamic range that surpasses existing radio images of the Milky Way by more than an order of magnitude. The source detection threshold at 20 cm is in the range 1-2 mJy over the 85% of the survey region (5{sup o} < l < 32{sup o}, |b| < 0.8{sup o}) not covered by bright extended emission; the angular resolution is {approx} 6''. We catalog over 3000 discrete sources (diameters mostly < 30'') and present an atlas of {approx} 400 diffuse emission regions. New and archival data at 90 cm for the whole survey area are also presented. Comparison of our catalogs and images with the MSX mid-infrared data allow us to provide preliminary discrimination between thermal and non-thermal sources. We identify 49 high-probability supernova remnant candidates, increasing by a factor of seven the number of known remnants with diameters smaller than 50 in the survey region; several are pulsar wind nebula candidates and/or very small diameter remnants (D < 45''). We report the tentative identification of several hundred H II regions based on a comparison with the mid-IR data; they range in size from unresolved ultra-compact sources to large complexes of diffuse emission on scales of half a degree. In several of the latter regions, cospatial nonthermal emission illustrates the interplay between stellar death and birth. We comment briefly on plans for followup observations and our extension of the survey; when complemented by data from ongoing X-ray and mid-IR observations, we expect MAGPIS to provide an important contribution to our understanding of the birth and death of massive stars in the Milky Way.

  1. Speckle decorrelation in Ultrasound-modulated optical tomography made by heterodyne holography

    CERN Document Server

    Gross, M

    2016-01-01

    Ultrasound-modulated optical tomography (UOT) is a technique that images optical contrast deep inside scattering media. Heterodyne holography is a promising tool able to detect the UOT tagged photons with high efficiency. In this work, we describe theoretically the detection of the tagged photon in heterodyne holography based UOT, show how to filter the untagged photon discuss, and discuss the effect of speckle decorrelation. We show that optimal detection sensitivity can obtain, if the frame exposure time is of the order of the decorrelation time.

  2. 2D sparse array transducer optimization for 3D ultrasound imaging

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jae Hoon; Park, Kwan Kyu [Dept. of Mechanical Convergence Engineering, Hanyang University, Seoul (Korea, Republic of)

    2016-12-15

    A 3D ultrasound image is desired in many medical examinations. However, the implementation of a 2D array, which is needed for a 3D image, is challenging with respect to fabrication, interconnection and cabling. A 2D sparse array, which needs fewer elements than a dense array, is a realistic way to achieve 3D images. Because the number of ways the elements can be placed in an array is extremely large, a method for optimizing the array configuration is needed. Previous research placed the target point far from the transducer array, making it impossible to optimize the array in the operating range. In our study, we focused on optimizing a 2D sparse array transducer for 3D imaging by using a simulated annealing method. We compared the far-field optimization method with the near-field optimization method by analyzing a point-spread function (PSF). The resolution of the optimized sparse array is comparable to that of the dense array.

  3. Imaging of surface wave phase velocities from array phase observations

    Science.gov (United States)

    Weidle, Christian; Maupin, Valerie

    2010-05-01

    While temporary deployments some 10 years ago were largely based on short-period seismometers, the availability of broadband instruments in instrument pools increased strongly in recent years and as such modern temporary deployments for passive seismological recordings often consist to a large extent, if not exclusively, of broadband instruments. This opens for new analysis approaches as the broadband seismic wavefield is obtained at a relatively high spatial sampling relative to the wavelength. In an attempt to infer surface wave phase velocity anomalies beneath Southern Norway based on data from a temporary network of 41 broadband instruments, we present a new approach to overcome the limitations of two-station phase measurements (on the great circle with the source) and instead exploit the two-dimensional nature of the wavefield by taking into account phase measurements at all stations of the array from a single event. This is based on the assumption that the wavefield is at least piecewise linear within the study region. By triangulation of the network region and linear estimation of the phase gradient in each triangle we get without further a priori assumptions a coarse image of the phase velocity variations within our network. The image can be significantly refined for a single event recording by stacking multiple images based on arbitrary subsets of the available data. Phase velocity anomalies measured from single event recordings can be biased and blurred by non-plane arriving wavefield, reflections and diffractions of heterogeneities. Therefore, by averaging over velocity fields from different events with varying backazimuths, artefacts are reduced and the recovered image significantly improved. Another way to improve the recovered structures is to take into account the spatial variation of the amplitude field. However, while the phase between two neighboring stations may be (at least close to) linear, the amplitude may not, hence estimation of the second

  4. Examining small molecule: HIV RNA interactions using arrayed imaging reflectometry

    Science.gov (United States)

    Chaimayo, Wanaruk; Miller, Benjamin L.

    2014-03-01

    Human Immunodeficiency Virus (HIV) has been the subject of intense research for more than three decades as it causes an uncurable disease: Acquired Immunodeficiency Syndrome, AIDS. In the pursuit of a medical treatment, RNAtargeted small molecules are emerging as promising targets. In order to understand the binding kinetics of small molecules and HIV RNA, association (ka) and dissociation (kd) kinetic constants must be obtained, ideally for a large number of sequences to assess selectivity. We have developed Aqueous Array Imaged Reflectometry (Aq-AIR) to address this challenge. Using a simple light interference phenomenon, Aq-AIR provides real-time high-throughput multiplex capabilities to detect binding of targets to surface-immobilized probes in a label-free microarray format. The second generation of Aq-AIR consisting of high-sensitivity CCD camera and 12-μL flow cell was fabricated. The system performance was assessed by real-time detection of MBNL1-(CUG)10 and neomycin B - HIV RNA bindings. The results establish this second-generation Aq-AIR to be able to examine small molecules binding to RNA sequences specific to HIV.

  5. Focal plane resolution and overlapped array time delay and integrate imaging

    Science.gov (United States)

    Grycewicz, Thomas J.; Cota, Stephen A.; Lomheim, Terrence S.; Kalman, Linda S.

    2010-06-01

    In this paper we model sub-pixel image registration for a generic earth-observing satellite system with a focal plane using two offset time delay and integrate (TDI) arrays in the focal plane to improve the achievable ground resolution over the resolution achievable with a single array. The modeling process starts with a high-resolution image as ground truth. The Parameterized Image Chain Analysis & Simulation Software (PICASSO) modeling tool is used to degrade the images to match the optical transfer function, sampling, and noise characteristics of the target system. The model outputs a pair of images with a separation close to the nominal half-pixel separation between the overlapped arrays. A registration estimation algorithm is used to measure the offset for image reconstruction. The two images are aligned and summed on a grid with twice the capture resolution. We compare the resolution in images between the inputs before overlap, the reconstructed image, and a simulation for the image which would have been captured on a focal plane with twice the resolution. We find the performance to always be better than the lower resolution baseline, and to approach the performance of the high-resolution array in the ideal case. We show that the overlapped array imager significantly outperforms both the conventional high- and low-resolution imagers in conditions with high image smear.

  6. Analysis on optical heterodyne frequency error of full-field heterodyne interferometer

    Science.gov (United States)

    Li, Yang; Zhang, Wenxi; Wu, Zhou; Lv, Xiaoyu; Kong, Xinxin; Guo, Xiaoli

    2017-06-01

    The full-field heterodyne interferometric measurement technology is beginning better applied by employing low frequency heterodyne acousto-optical modulators instead of complex electro-mechanical scanning devices. The optical element surface could be directly acquired by synchronously detecting the received signal phases of each pixel, because standard matrix detector as CCD and CMOS cameras could be used in heterodyne interferometer. Instead of the traditional four-step phase shifting phase calculating, Fourier spectral analysis method is used for phase extracting which brings lower sensitivity to sources of uncertainty and higher measurement accuracy. In this paper, two types of full-field heterodyne interferometer are described whose advantages and disadvantages are also specified. Heterodyne interferometer has to combine two different frequency beams to produce interference, which brings a variety of optical heterodyne frequency errors. Frequency mixing error and beat frequency error are two different kinds of inescapable heterodyne frequency errors. In this paper, the effects of frequency mixing error to surface measurement are derived. The relationship between the phase extraction accuracy and the errors are calculated. :: The tolerance of the extinction ratio of polarization splitting prism and the signal-to-noise ratio of stray light is given. The error of phase extraction by Fourier analysis that caused by beat frequency shifting is derived and calculated. We also propose an improved phase extraction method based on spectrum correction. An amplitude ratio spectrum correction algorithm with using Hanning window is used to correct the heterodyne signal phase extraction. The simulation results show that this method can effectively suppress the degradation of phase extracting caused by beat frequency error and reduce the measurement uncertainty of full-field heterodyne interferometer.

  7. Acoustical cross-talk in row–column addressed 2-D transducer arrays for ultrasound imaging

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Jensen, Jørgen Arendt; Thomsen, Erik Vilain

    2015-01-01

    The acoustical cross-talk in row–column addressed 2-D transducer arrays for volumetric ultrasound imaging is investigated. Experimental results from a 2.7 MHz, λ/2-pitch capacitive micromachined ultrasonic transducer (CMUT) array with 62 rows and 62 columns are presented and analyzed in the frequ......The acoustical cross-talk in row–column addressed 2-D transducer arrays for volumetric ultrasound imaging is investigated. Experimental results from a 2.7 MHz, λ/2-pitch capacitive micromachined ultrasonic transducer (CMUT) array with 62 rows and 62 columns are presented and analyzed...

  8. BI-ground microstrip array coil vs. conventional microstrip array coil for mouse imaging at 7 tesla

    Science.gov (United States)

    Hernández, Ricardo; Terrones, M. A. López; Jakob, P. M.

    2012-10-01

    At high field strengths, the need for more efficient high frequency coils has grown. Since the radiation losses and the interaction between coil and sample increase proportionally to field strength, the quality factor (Q) and the sensitivity of the coil decrease as consequence of these negative effects. Since Zhang et al proposed in 2001 a new surface coil based on the microstrip transmission line for high frequency, different Tx-Rx phased arrays based on this concept have been already introduced in animal and whole body systems at high field strengths, each of them with different modifications in order to get better field homogeneity, SNR or isolation between coil elements in the array. All these arrays for animals systems have been built for rat imaging. One of these modifications is called BI-Ground Microstrip Array Coil (BIGMAC). The implementation of a smaller two-channel BIGMAC design for mouse imaging is studied and its performance compared to a two-channel conventional Microstrip array at 7 Tesla, the higher isolation by using BIGMAC elements in comparison with conventional Microstrip elements is shown in this work.

  9. Switched Antenna Array Tile for Real-Time Microwave Imaging Aperture

    Science.gov (United States)

    2016-06-26

    and is compatible with fast imaging techniques. Details on the design and realization of the tile are presented, as well as experimental images...mass transit systems, stadiums , public events). To this end, the system notionally depicted in Fig. 1 is currently under development at MIT Lincoln...of that array. In the next section, the design of the array and tile are discussed, while initial imaging results are presented in Section III. II

  10. Subsurface contrast due to friction in heterodyne force microscopy

    Science.gov (United States)

    Verbiest, G. J.; Oosterkamp, T. H.; Rost, M. J.

    2017-02-01

    The nondestructive imaging of subsurface structures on the nanometer scale has been a long-standing desire in both science and industry. A few impressive images were published so far that demonstrate the general feasibility by combining ultrasound with an atomic force microscope. From different excitation schemes, heterodyne force microscopy seems to be the most promising candidate delivering the highest contrast and resolution. However, the physical contrast mechanism is unknown, thereby preventing any quantitative analysis of samples. Here we show that friction at material boundaries within the sample is responsible for the contrast formation. This result is obtained by performing a full quantitative analysis, in which we compare our experimentally observed contrasts with simulations and calculations. Surprisingly, we can rule out all other generally believed responsible mechanisms, like Rayleigh scattering, sample (visco)elasticity, damping of the ultrasonic tip motion, and ultrasound attenuation. Our analytical description paves the way for quantitative subsurface-AFM imaging.

  11. A 32-Channel Head Coil Array with Circularly Symmetric Geometry for Accelerated Human Brain Imaging.

    Directory of Open Access Journals (Sweden)

    Ying-Hua Chu

    Full Text Available The goal of this study is to optimize a 32-channel head coil array for accelerated 3T human brain proton MRI using either a Cartesian or a radial k-space trajectory. Coils had curved trapezoidal shapes and were arranged in a circular symmetry (CS geometry. Coils were optimally overlapped to reduce mutual inductance. Low-noise pre-amplifiers were used to further decouple between coils. The SNR and noise amplification in accelerated imaging were compared to results from a head coil array with a soccer-ball (SB geometry. The maximal SNR in the CS array was about 120% (1070 vs. 892 and 62% (303 vs. 488 of the SB array at the periphery and the center of the FOV on a transverse plane, respectively. In one-dimensional 4-fold acceleration, the CS array has higher averaged SNR than the SB array across the whole FOV. Compared to the SB array, the CS array has a smaller g-factor at head periphery in all accelerated acquisitions. Reconstructed images using a radial k-space trajectory show that the CS array has a smaller error than the SB array in 2- to 5-fold accelerations.

  12. Heterodyne displacement interferometer, insensitive for input polarization

    NARCIS (Netherlands)

    Meskers, A.J.H.; Spronck, J.W.; Munnig Schmidt, R.H.

    2014-01-01

    Periodic nonlinearity (PNL) in displacement interferometers is a systematic error source that limits measurement accuracy. The PNL of coaxial heterodyne interferometers is highly influenced by the polarization state and orientation of the source frequencies. In this Letter, we investigate this error

  13. Laser Metrology Heterodyne Phase-Locked Loop

    Science.gov (United States)

    Loya, Frank; Halverson, Peter

    2009-01-01

    A method reduces sensitivity to noise in a signal from a laser heterodyne interferometer. The phase-locked loop (PLL) removes glitches that occur in a zero-crossing detector s output [that can happen if the signal-to-noise ratio (SNR) of the heterodyne signal is low] by the use of an internal oscillator that produces a square-wave signal at a frequency that is inherently close to the heterodyne frequency. It also contains phase-locking circuits that lock the phase of the oscillator to the output of the zero-crossing detector. Because the PLL output is an oscillator signal, it is glitch-free. This enables the ability to make accurate phase measurements in spite of low SNR, creates an immunity to phase error caused by shifts in the heterodyne frequency (i.e. if the target moves causing Doppler shift), and maintains a valid phase even when the signal drops out for brief periods of time, such as when the laser is blocked by a stray object.

  14. Low Power X-Ray Photon Resolving Imaging Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The solid-state detector array is the primary technology to implement the current generation of space borne high-energy astronomy missions that are managed by NASA...

  15. Cross-Correlation Properties of Costas Arrays and Their Images under Horizontal and Vertical Flips

    Directory of Open Access Journals (Sweden)

    Konstantinos Drakakis

    2008-01-01

    Full Text Available We consider the cross-correlation of a Costas array with its image under a horizontal and/or a vertical flip. We propose and prove several bounds on the maximal cross-correlation and on its value at the origin, for both general Costas arrays and for algebraically constructed ones.

  16. Comparison of 3-D Synthetic Aperture Phased-Array Ultrasound Imaging and Parallel Beamforming

    DEFF Research Database (Denmark)

    Rasmussen, Morten Fischer; Jensen, Jørgen Arendt

    2014-01-01

    This paper demonstrates that synthetic apertureimaging (SAI) can be used to achieve real-time 3-D ultra-sound phased-array imaging. It investigates whether SAI in-creases the image quality compared with the parallel beam-forming (PB) technique for real-time 3-D imaging. Data areobtained using bot...

  17. High Performance Dual Band Photodetector Arrays for MWIR/LWIR Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Hyperspectral imaging arrays offer far more data and the ability to discriminate objects being observed. Continued difficulties with applying HgCdTe materials,...

  18. Three-dimensional real-time synthetic aperture imaging using a rotating phased array transducer

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Dufait, Remi; Schoisswohl, Armin

    2002-01-01

    Current 3D real-time imaging is done either with sparse 2D arrays, or with mechanically moved phased arrays. The former results in a poor resolution and contrast due to a limited amount of elements. The latter has the disadvantage of low frame rates due to the sequential acquisition of the volume...... line-by-line and plane-by-plane. This paper describes an approach which combines mechanically moved phased array with synthetic transmit aperture imaging, resulting in high volume acquisition rates without a trade-off in image quality. The scan method uses a conventional fully populated 64 element...... phased array, which is rotated over the volume of interest. The data is acquired using coded signals and synthetic transmit aperture imaging. Only one group of elements transmits at a time. The delays are set such as to form a cylindrical wave. The back-scattered signal carries information not only from...

  19. Influence of microlens array manufacturing errors on light-field imaging

    Science.gov (United States)

    Li, Su-Ning; Yuan, Yuan; Liu, Bin; Wang, Fu-Qiang; Tan, He-Ping

    2018-03-01

    A microlens array (MLA) is a key optical element for four-dimensional light-field analysis in a light-field camera. MLA manufacturing errors affect light-field imaging, but their effects, especially on the physical imaging process and image-degradation mechanism, have not entirely been studied. In this paper, we develop a manufacturing-error model for MLA and quantitatively analyze raw images and refocused images using image quality evaluation indexes. The results indicate that manufacturing errors cause changes in image features including brightness, resolution, and spot position. The image-features undergo changes and the degree of degradation caused by different error types showed great differences.

  20. Algorithm-structured computer arrays and networks architectures and processes for images, percepts, models, information

    CERN Document Server

    Uhr, Leonard

    1984-01-01

    Computer Science and Applied Mathematics: Algorithm-Structured Computer Arrays and Networks: Architectures and Processes for Images, Percepts, Models, Information examines the parallel-array, pipeline, and other network multi-computers.This book describes and explores arrays and networks, those built, being designed, or proposed. The problems of developing higher-level languages for systems and designing algorithm, program, data flow, and computer structure are also discussed. This text likewise describes several sequences of successively more general attempts to combine the power of arrays wi

  1. A mobile ferromagnetic shape detection sensor using a Hall sensor array and magnetic imaging.

    Science.gov (United States)

    Misron, Norhisam; Shin, Ng Wei; Shafie, Suhaidi; Marhaban, Mohd Hamiruce; Mailah, Nashiren Farzilah

    2011-01-01

    This paper presents a mobile Hall sensor array system for the shape detection of ferromagnetic materials that are embedded in walls or floors. The operation of the mobile Hall sensor array system is based on the principle of magnetic flux leakage to describe the shape of the ferromagnetic material. Two permanent magnets are used to generate the magnetic flux flow. The distribution of magnetic flux is perturbed as the ferromagnetic material is brought near the permanent magnets and the changes in magnetic flux distribution are detected by the 1-D array of the Hall sensor array setup. The process for magnetic imaging of the magnetic flux distribution is done by a signal processing unit before it displays the real time images using a netbook. A signal processing application software is developed for the 1-D Hall sensor array signal acquisition and processing to construct a 2-D array matrix. The processed 1-D Hall sensor array signals are later used to construct the magnetic image of ferromagnetic material based on the voltage signal and the magnetic flux distribution. The experimental results illustrate how the shape of specimens such as square, round and triangle shapes is determined through magnetic images based on the voltage signal and magnetic flux distribution of the specimen. In addition, the magnetic images of actual ferromagnetic objects are also illustrated to prove the functionality of mobile Hall sensor array system for actual shape detection. The results prove that the mobile Hall sensor array system is able to perform magnetic imaging in identifying various ferromagnetic materials.

  2. Color filter array pattern identification using variance of color difference image

    Science.gov (United States)

    Shin, Hyun Jun; Jeon, Jong Ju; Eom, Il Kyu

    2017-07-01

    A color filter array is placed on the image sensor of a digital camera to acquire color images. Each pixel uses only one color, since the image sensor can measure only one color per pixel. Therefore, empty pixels are filled using an interpolation process called demosaicing. The original and the interpolated pixels have different statistical characteristics. If the image is modified by manipulation or forgery, the color filter array pattern is altered. This pattern change can be a clue for image forgery detection. However, most forgery detection algorithms have the disadvantage of assuming the color filter array pattern. We present an identification method of the color filter array pattern. Initially, the local mean is eliminated to remove the background effect. Subsequently, the color difference block is constructed to emphasize the difference between the original pixel and the interpolated pixel. The variance measure of the color difference image is proposed as a means of estimating the color filter array configuration. The experimental results show that the proposed method is effective in identifying the color filter array pattern. Compared with conventional methods, our method provides superior performance.

  3. 3D morphology reconstruction using linear array CCD binocular stereo vision imaging system

    Science.gov (United States)

    Pan, Yu; Wang, Jinjiang

    2018-01-01

    Binocular vision imaging system, which has a small field of view, cannot reconstruct the 3-D shape of the dynamic object. We found a linear array CCD binocular vision imaging system, which uses different calibration and reconstruct methods. On the basis of the binocular vision imaging system, the linear array CCD binocular vision imaging systems which has a wider field of view can reconstruct the 3-D morphology of objects in continuous motion, and the results are accurate. This research mainly introduces the composition and principle of linear array CCD binocular vision imaging system, including the calibration, capture, matching and reconstruction of the imaging system. The system consists of two linear array cameras which were placed in special arrangements and a horizontal moving platform that can pick up objects. The internal and external parameters of the camera are obtained by calibrating in advance. And then using the camera to capture images of moving objects, the results are then matched and 3-D reconstructed. The linear array CCD binocular vision imaging systems can accurately measure the 3-D appearance of moving objects, this essay is of great significance to measure the 3-D morphology of moving objects.

  4. A Novel ASI Array for Redline Auroral Imaging across Northern Canada

    Science.gov (United States)

    Unick, C.; Donovan, E.; Spanswick, E.; Jackel, B. J.; Groves, P.; McGuffin, N.; Chaddock, D.; James, S.; Lambrinoudis, C.

    2014-12-01

    The redline aurora is a tracer of magnetospheric structure and dynamics. From drifting polar cap patches to bursty bulk flows (BBFs) in the mid-tail, the redline aurora provides key information about system-level dynamics and coupling between plasma regimes. In this paper we present a new all-sky imager (ASI) array that measures the 6300Å emission line from neutral Oxygen in the aurora. The array coverage extends from south of Gillam, Manitoba, to north of Resolute Bay, Nunavut, and to the west of Fort Smith, NWT, and the array is synchronized at 3 second cadence in the same manner that the THEMIS ASI array is. The camera has superior resolution and noise performance compared to previous generations of auroral cameras. The imager employs only one filter and thus monitors one auroral line throughout the array simultaneously and continuously (at high cadence). The new design has better immunity to internal scatter and produces images of faint aurora when the moon is in the field of view, which corrects another deficiency of some currently deployed auroral imager systems. We present the new instrument design, test data from the commissioning phase of the array deployment, and thoughts on the scientific potential of the array.

  5. Analysis and System Design Framework for Infrared Spatial Heterodyne Spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Cooke, B.J.; Smith, B.W.; Laubscher, B.E.; Villeneuve, P.V.; Briles, S.D.

    1999-04-05

    The authors present a preliminary analysis and design framework developed for the evaluation and optimization of infrared, Imaging Spatial Heterodyne Spectrometer (SHS) electro-optic systems. Commensurate with conventional interferometric spectrometers, SHS modeling requires an integrated analysis environment for rigorous evaluation of system error propagation due to detection process, detection noise, system motion, retrieval algorithm and calibration algorithm. The analysis tools provide for optimization of critical system parameters and components including : (1) optical aperture, f-number, and spectral transmission, (2) SHS interferometer grating and Littrow parameters, and (3) image plane requirements as well as cold shield, optical filtering, and focal-plane dimensions, pixel dimensions and quantum efficiency, (4) SHS spatial and temporal sampling parameters, and (5) retrieval and calibration algorithm issues.

  6. Three-dimensional near-field MIMO array imaging using range migration techniques.

    Science.gov (United States)

    Zhuge, Xiaodong; Yarovoy, Alexander G

    2012-06-01

    This paper presents a 3-D near-field imaging algorithm that is formulated for 2-D wideband multiple-input-multiple-output (MIMO) imaging array topology. The proposed MIMO range migration technique performs the image reconstruction procedure in the frequency-wavenumber domain. The algorithm is able to completely compensate the curvature of the wavefront in the near-field through a specifically defined interpolation process and provides extremely high computational efficiency by the application of the fast Fourier transform. The implementation aspects of the algorithm and the sampling criteria of a MIMO aperture are discussed. The image reconstruction performance and computational efficiency of the algorithm are demonstrated both with numerical simulations and measurements using 2-D MIMO arrays. Real-time 3-D near-field imaging can be achieved with a real-aperture array by applying the proposed MIMO range migration techniques.

  7. Development of macropore arrays in silicon and related technologies for X-ray imaging applications

    OpenAIRE

    Badel, Xavier

    2003-01-01

    Digital devices have started to replace photographic film inX-ray imaging applications. As compared to photographic films,these devices are more convenient to obtain images and tohandle, treat and store these images. The goal of the presentstudy is to develop macropore arrays and related silicontechnologies in order to fabricate X-ray imaging detectors formedical applications, and in particular for dentistry. Althougha few detectors are already available on the market, theirperformances, such...

  8. Color Restoration of RGBN Multispectral Filter Array Sensor Images Based on Spectral Decomposition

    OpenAIRE

    Chulhee Park; Moon Gi Kang

    2016-01-01

    A multispectral filter array (MSFA) image sensor with red, green, blue and near-infrared (NIR) filters is useful for various imaging applications with the advantages that it obtains color information and NIR information simultaneously. Because the MSFA image sensor needs to acquire invisible band information, it is necessary to remove the IR cut-offfilter (IRCF). However, without the IRCF, the color of the image is desaturated by the interference of the additional NIR component of each RGB co...

  9. Synthetic Receive Beamforming and Image Acquisition Capabilities Using an 8 x 128 1.75D Array

    DEFF Research Database (Denmark)

    Fernandez, Anna T.; Gammelmark, Kim; Dahl, Jeremy J.

    2003-01-01

    Ultrasound imaging can be improved with higher order arrays through elevation dynamic focusing in future, higher channel count systems. However, modifications to current system hardware could yield increased imaging depth-of-field with 1.75D arrays (arrays with individually addressable elements, ...

  10. Echo decorrelation imaging of ex vivo HIFU and bulk ultrasound ablation using image-treat arrays

    Science.gov (United States)

    Fosnight, Tyler R.; Hooi, Fong Ming; Colbert, Sadie B.; Keil, Ryan D.; Barthe, Peter G.; Mast, T. Douglas

    2017-03-01

    In this study, the ability of ultrasound echo decorrelation imaging to map and predict heat-induced cell death was tested using bulk ultrasound thermal ablation, high intensity focused ultrasound (HIFU) thermal ablation, and pulse-echo imaging of ex vivo liver tissue by a custom image-treat array. Tissue was sonicated at 5.0 MHz using either pulses of unfocused ultrasound (N=12) (7.5 s, 50.9-101.8 W/cm2 in situ spatial-peak, temporal-peak intensity) for bulk ablation or focused ultrasound (N=21) (1 s, 284-769 W/cm2 in situ spatial-peak, temporal-peak intensity and focus depth of 10 mm) for HIFU ablation. Echo decorrelation and integrated backscatter (IBS) maps were formed from radiofrequency pulse-echo images captured at 118 frames per second during 5.0 s rest periods, beginning 1.1 s after each sonication pulse. Tissue samples were frozen at -80˚C, sectioned, vitally stained, imaged, and semi-automatically segmented for receiver operating characteristic (ROC) analysis. ROC curves were constructed to assess prediction performance for echo decorrelation and IBS. Logarithmically scaled mean echo decorrelation in non-ablated and ablated tissue regions before and after electronic noise and motion correction were compared. Ablation prediction by echo decorrelation and IBS was significant for both focused and bulk ultrasound ablation. The log10-scaled mean echo decorrelation was significantly greater in regions of ablation for both HIFU and bulk ultrasound ablation. Echo decorrelation due to electronic noise and motion was significantly reduced by correction. These results suggest that ultrasound echo decorrelation imaging is a promising approach for real-time prediction of heat-induced cell death for guidance and monitoring of clinical thermal ablation, including radiofrequency ablation and HIFU.

  11. Superconducting Microwave Resonator Arrays for Submillimeter/Far-Infrared Imaging

    Science.gov (United States)

    Noroozian, Omid

    Superconducting microwave resonators have the potential to revolutionize submillimeter and far-infrared astronomy, and with it our understanding of the universe. The field of low-temperature detector technology has reached a point where extremely sensitive devices like transition-edge sensors are now capable of detecting radiation limited by the background noise of the universe. However, the size of these detector arrays are limited to only a few thousand pixels. This is because of the cost and complexity of fabricating large-scale arrays of these detectors that can reach up to 10 lithographic levels on chip, and the complicated SQUID-based multiplexing circuitry and wiring for readout of each detector. In order to make substantial progress, next-generation ground-based telescopes such as CCAT or future space telescopes require focal planes with large-scale detector arrays of 104--10 6 pixels. Arrays using microwave kinetic inductance detectors (MKID) are a potential solution. These arrays can be easily made with a single layer of superconducting metal film deposited on a silicon substrate and pattered using conventional optical lithography. Furthermore, MKIDs are inherently multiplexable in the frequency domain, allowing ˜ 10 3 detectors to be read out using a single coaxial transmission line and cryogenic amplifier, drastically reducing cost and complexity. An MKID uses the change in the microwave surface impedance of a superconducting thin-film microresonator to detect photons. Absorption of photons in the superconductor breaks Cooper pairs into quasiparticles, changing the complex surface impedance, which results in a perturbation of resonator frequency and quality factor. For excitation and readout, the resonator is weakly coupled to a transmission line. The complex amplitude of a microwave probe signal tuned on-resonance and transmitted on the feedline past the resonator is perturbed as photons are absorbed in the superconductor. The perturbation can be

  12. An Axial Array for Volumetric Intravascular Ultrasound Imaging

    NARCIS (Netherlands)

    Alles, E.J.

    2012-01-01

    Intravascular ultrasound (IVUS) is a medical imaging modality aimed at imaging blood vessel walls from within the vessel. Current commercial IVUS catheters are designed to yield two-dimensional cross-sectional images perpendicular to the vessel wall. By pulling the catheter back through the artery

  13. Waveguide piezoelectric micromachined ultrasonic transducer array for short-range pulse-echo imaging

    Science.gov (United States)

    Lu, Y.; Tang, H.; Wang, Q.; Fung, S.; Tsai, J. M.; Daneman, M.; Boser, B. E.; Horsley, D. A.

    2015-05-01

    This paper presents an 8 × 24 element, 100 μm-pitch, 20 MHz ultrasound imager based on a piezoelectric micromachined ultrasonic transducer (PMUT) array having integrated acoustic waveguides. The 70 μm diameter, 220 μm long waveguides function both to direct acoustic waves and to confine acoustic energy, and also to provide mechanical protection for the PMUT array used for surface-imaging applications such as an ultrasonic fingerprint sensor. The imager consists of a PMUT array bonded with a CMOS ASIC using wafer-level conductive eutectic bonding. This construction allows each PMUT in the array to have a dedicated front-end receive amplifier, which together with on-chip analog multiplexing enables individual pixel read-out with high signal-to-noise ratio through minimized parasitic capacitance between the PMUT and the front-end amplifier. Finite element method simulations demonstrate that the waveguides preserve the pressure amplitude of acoustic pulses over distances of 600 μm. Moreover, the waveguide design demonstrated here enables pixel-by-pixel readout of the ultrasound image due to improved directivity of the PMUT by directing acoustic waves and creating a pressure field with greater spatial uniformity at the end of the waveguide. Pulse-echo imaging experiments conducted using a one-dimensional steel grating demonstrate the array's ability to form a two-dimensional image of a target.

  14. Ozone height profiles using laser heterodyne radiometer

    Science.gov (United States)

    Jain, S. L.

    1994-01-01

    The monitoring of vertical profiles of ozone and related minor constituents in the atmosphere are of great significance to understanding the complex interaction between atmospheric dynamics, chemistry and radiation budget. An ultra high spectral resolution tunable CO2 laser heterodyne radiometer has been designed, developed and set up at the National Physical Laboratory, New Delhi to obtain vertical profiles of various minor constituents the characteristic absorption lines in 9 to 11 micron spectral range. Due to its high spectral resolution the lines can be resolved completely and data obtained are inverted to get vertical profiles using an inversion technique developed by the author. In the present communication the salient features of the laser heterodyne system and the results obtained are discussed in detail.

  15. Heterodyne high-spectral-resolution lidar.

    Science.gov (United States)

    Chouza, Fernando; Witschas, Benjamin; Reitebuch, Oliver

    2017-10-10

    In this work, a novel lidar technique to perform high-spectral-resolution measurements of the atmospheric backscatter is discussed and the first results are presented. The proposed method, which relies on a heterodyne detection receiver, allows us not only to separate the molecular and the aerosol component of the atmospheric backscatter, but also to investigate the spectral shape of the Rayleigh-Brillouin line. As in the case of the direct-detection high-spectral-resolution lidars, the separation of the different scattering processes would allow an independent system calibration and aerosol extinction measurements. The proposed retrieval technique was successfully tested on the Deutsches Zentrum für Luft- und Raumfahrt airborne Doppler wind lidar system with measurements conducted during different measurement campaigns and under different atmospheric conditions. In light of these results, further ideas for the implementation of a dedicated heterodyne high-spectral-resolution lidar are discussed.

  16. Temporal heterodyne shearing speckle pattern interferometry

    Science.gov (United States)

    Wang, Xu; Gao, Zhan; Qin, Jie; Zhang, Xiaoqiong; Yang, Shanwei

    2017-06-01

    Shearing speckle pattern interferometry is a full-field speckle interferometric technique used to determine surface displacement derivatives. In this paper, a new measurement system of real-time heterodyne shearography interferometry is presented. This system combined with heterodyne measurement, shearography interferometry and time domain signal processing technology can dynamically detect the out-of-plane displacement gradient. The principles and system arrangement are described. Using the Jones matrix, the mathematical expression of light intensity distribution passing through this system is deduced. A preliminary experiment was performed to demonstrate the performance of this new device, and simulations were conducted using the finite element method. Comparison of results shows that quantitative measurement of the displacement derivative has been achieved.

  17. UWB Antennas and MIMO Antenna Arrays Development for Near-Field Imaging

    NARCIS (Netherlands)

    Yang, Y.

    2011-01-01

    UWB radar is the most promising radar system for the future. In addition, by combining the UWB and array signal processing, one can obtain 3-D images of the objects for classification and identification, which is very useful in many applications. To achieve high-resolution real-time 3-D imaging

  18. 3-D Imaging using Row--Column-Addressed 2-D Arrays with a Diverging Lens

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Engholm, Mathias; Stuart, Matthias Bo

    2016-01-01

    , is designed for imaging down to 14 cm at a volume rate of 88 Hz. The curvilinear imaging performance of a λ/2-pitch 3 MHz 62+62 RCA 2-D array is investigated as a function of depth, using a diverging lens with f-number of -1. The results of this study demonstrate that the proposed beamforming approach...

  19. Comparison Between Eight- and Sixteen-Channel TEM Transceive Arrays for Body Imaging at 7 Tesla

    Science.gov (United States)

    Snyder, CJ; DelaBarre, L; Moeller, S; Tian, J; Akgun, C; Van De Moortele, P-F; Bolan, PJ; Ugurbil, K; Vaughan, JT; Metzger, GJ

    2011-01-01

    Eight- and sixteen-channel transceive stripline/TEM body arrays were compared at 7 tesla (297 MHz) both in simulation and experimentally. Despite previous demonstrations of similar arrays for use in body applications, a quantitative comparison of the two configurations has not been undertaken to date. Results were obtained on a male pelvis for assessing transmit, SNR and parallel imaging performance and to evaluate local power deposition versus transmit B1 (B1+). All measurements and simulations were conducted after performing local B1+ phase shimming in the region of the prostate. Despite the additional challenges of decoupling immediately adjacent coils, the sixteen-channel array demonstrated improved or nearly equivalent performance to the eight-channel array based on the evaluation criteria. Experimentally, transmit performance and SNR were 22% higher for the sixteen-channel array while significantly increased reduction factors were achievable in the left-right direction for parallel imaging. Finite-difference time-domain simulations demonstrated similar results with respect to transmit and parallel imaging performance, however a higher transmit efficiency advantage of 33% was predicted. Simulations at both 3T and 7T verified the expected parallel imaging improvements with increasing field strength and showed that, for a specific B1+ shimming strategy employed, the sixteen-channel array exhibited lower local and global SAR for a given B1+. PMID:22102483

  20. Dispersion-based imaging for structural health monitoring using sparse and compact arrays

    Science.gov (United States)

    Quaegebeur, N.; Masson, P.; Langlois-Demers, D.; Micheau, P.

    2011-02-01

    In this paper, a technique called 'excitelet' is presented for the imaging of damage in structures using the correlation of the signals measured at elements of piezoceramic arrays with dispersed versions of the excitation signal. This approach is presented as an extension of classical imaging techniques and takes advantage of the chirplet-based matching pursuit algorithm. The applicability for sparse and compact arrays is investigated experimentally on an aluminum plate and comparison with the existing embedded ultrasonic structural radar (EUSR) algorithm is performed for A0 and S0 modes for three frequency ranges of interest. Significant improvement of imaging quality is demonstrated with respect to imaging techniques using time-of-flight (ToF) and group velocity considerations for both sparse and compact piezoceramic array arrangements.

  1. 3D Imaging Algorithm for Down-Looking MIMO Array SAR Based on Bayesian Compressive Sensing

    Directory of Open Access Journals (Sweden)

    Xiaozhen Ren

    2014-01-01

    Full Text Available Down-looking MIMO array SAR can reconstruct 3D images of the observed area in the inferior of the platform of the SAR and has wide application prospects. In this paper, a new strategy based on Bayesian compressive sensing theory is proposed for down-looking MIMO array SAR imaging, which transforms the cross-track imaging process of down-looking MIMO array SAR into the problem of sparse signal reconstruction from noisy measurements. Due to account for additive noise encountered in the measurement process, high quality image can be achieved. Simulation results indicate that the proposed method can provide better resolution and lower sidelobes compared to the conventional method.

  2. Isotropic high resolution optoacoustic imaging with linear detector arrays in bi-directional scanning.

    Science.gov (United States)

    Schwarz, Mathias; Buehler, Andreas; Ntziachristos, Vasilis

    2015-01-01

    Optoacoustic (photoacoustic) imaging is often performed with one-dimensional transducer arrays, in analogy to ultrasound imaging. Optoacoustic imaging using linear arrays offers ease of implementation but comes with several performance drawbacks, in particular poor elevation resolution, i.e. the resolution along the axis perpendicular to the focal plane. Herein, we introduce and investigate a bi-directional scanning approach using linear arrays that can improve the imaging performance to quasi-isotropic transverse resolution. We study the approach theoretically and perform numerical simulations and phantom measurements to evaluate its performance under defined conditions. Finally, we discuss the features and the limitations of the proposed method. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. SHIMS -- A Spatial Heterodyne Interferometer for Methane Sounding Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project develops the Spatial Heterodyne Interferometer for Methane Sounding (SHIMS), a lightweight, compact, robust spectrometer system for remote sensing of...

  4. Comparative Study on Ultrasonic Imaging Methods with Array Transducers

    Science.gov (United States)

    Matsuoka, C.; Nakahata, K.; Baba, A.; Kono, N.; Hirose, S.

    2008-02-01

    The performance of ultrasonic imaging methods developed in time domain and frequency domain algorithms is investigated in this study. The sectorial synthetic aperture focusing technique (S-SAFT) outputs the flaw image by superposing the sector-scan images obtained at various measurement points in the time domain. The inverse scattering imaging method (ISIM) is based on the elastodynamic inversion in the frequency domain and reconstructs the mathematical function which represents the flaw shape. The advantages and usabilities of these methods are discussed, taking into account the practical application to the NDE field.

  5. A 58 x 62 pixel Si:Ga array camera for 5 - 14 micron astronomical imaging

    Science.gov (United States)

    Gezari, D. Y.; Folz, W. C.; Woods, L. A.; Wooldridge, J. B.

    1989-01-01

    A new infrared array camera system has been successfully applied to high background 5 - 14 micron astronomical imaging photometry observations, using a hybrid 58 x 62 pixel Si:Ga array detector. The off-axis reflective optical design incorporating a parabolic camera mirror, circular variable filter wheel, and cold aperture stop produces diffraction-limited images with negligible spatial distortion and minimum thermal background loading. The camera electronic system architecture is divided into three subsystems: (1) high-speed analog front end, including 2-channel preamp module, array address timing generator, bias power suppies, (2) two 16 bit, 3 microsec per conversion A/D converters interfaced to an arithmetic array processor, and (3) an LSI 11/73 camera control and data analysis computer. The background-limited observational noise performance of the camera at the NASA/IRTF telescope is NEFD (1 sigma) = 0.05 Jy/pixel min exp 1/2.

  6. Comparison of digital beamforming algorithms for 3-D terahertz imaging with sparse multistatic line arrays

    Directory of Open Access Journals (Sweden)

    B. Baccouche

    2017-12-01

    Full Text Available In this contribution we compare the back-projection algorithm with our recently developed modified range migration algorithm for 3-D terahertz imaging using sparse multistatic line arrays. A 2-D planar sampling scheme is generated using the array's aperture in combination with an orthogonal synthetic aperture obtained through linear movement of the object under test. A stepped frequency continuous wave signal modulation is used for range focusing. Comparisons of the focusing quality show that results using the modified range migration algorithm reflect these of the back-projection algorithm except for some degradation along the array's axis due to the operation in the array's near-field. Nevertheless the highest computational efficiency is obtained from the modified range migration algorithm, which is better than the numerically optimized version of the back-projection algorithm. Measurements have been performed by using an imaging system operating in the W frequency band to verify the theoretical results.

  7. Gallium arsenide quantum well-based far infrared array radiometric imager

    Science.gov (United States)

    Forrest, Kathrine A.; Jhabvala, Murzy D.

    1991-01-01

    We have built an array-based camera (FIRARI) for thermal imaging (lambda = 8 to 12 microns). FIRARI uses a square format 128 by 128 element array of aluminum gallium arsenide quantum well detectors that are indium bump bonded to a high capacity silicon multiplexer. The quantum well detectors offer good responsivity along with high response and noise uniformity, resulting in excellent thermal images without compensation for variation in pixel response. A noise equivalent temperature difference of 0.02 K at a scene temperature of 290 K was achieved with the array operating at 60 K. FIRARI demonstrated that AlGaAS quantum well detector technology can provide large format arrays with performance superior to mercury cadmium telluride at far less cost.

  8. MTF measurements with high-resolution a-Si:H imaging arrays

    Science.gov (United States)

    Yorkston, John; Antonuk, Larry E.; Seraji, N.; Huang, Weidong; Siewerdsen, Jeffrey H.; El-Mohri, Youcef

    1995-05-01

    Recent advances in a-Si:H fabrication technology have opened the way for the application of flat panel imaging arrays in a number of areas in medical imaging. Their large area (up to approximately 26 X 26 cm), thin profile (x-ray imaging technologies such as film and image intensifier systems. As a first step towards a device suitable for clinical use we have created a 24.4 X 19.4 cm array with 127 micrometers pitch pixels. This device serves as a testbed for investigating the effects of design changes on array imaging performance. This paper reports on initial measurements of the spatial resolution of this device used in conjunction with an overlaying Lanex Regular screen and 90 kVp x rays. The measured pre-sampled modulation transfer function (p.s. MTF) is found to fall below the predicted value by up to approximately 8%. At least part of this reduction seems to be due to scattering of light photons between the array and the surface of the phosphor screen contacting the array.

  9. Luminescence imaging strategies for drone-based PV array inspection

    DEFF Research Database (Denmark)

    Benatto, Gisele Alves dos Reis; Riedel, Nicholas; Mantel, Claire

    2017-01-01

    The goal of this work is to perform outdoor defect detection imaging that will be used in a fast, accurate and automatic drone-based survey system for PV power plants. The imaging development focuses on techniques that do not require electrical contact, permitting automatic drone inspections...

  10. Luminescence Imaging Strategies for Drone-Based PV Array Inspection

    DEFF Research Database (Denmark)

    Benatto, Gisele Alves dos Reis; Riedel, Nicholas; Mantel, Claire

    2017-01-01

    The goal of this work is to develop outdoor defect detection imaging and understand fully its challenges and limitations. The imaging is based on luminescence strategies that will be used for fast and accurate UAV-based inspection system for PV power plants. We studied electroluminescence (EL...

  11. THz Imaging Using Uncooled Wideband Direct Detection Focal Plane Arrays

    NARCIS (Netherlands)

    van Berkel, S.L.; Yurduseven, O.; Freni, Angelo; Neto, A.; Llombart Juan, N.

    2017-01-01

    In millimeter and submillimeter-wave radiometric imaging systems, a persistent goal is the increase in the speed of acquisition of the image while maintaining a high sensitivity. Typically, the highest sensitivity is achieved by cryogenically cooling the detectors, specifically in astronomical

  12. Geometric Correction of Airborne Linear Array Image Based on Bias Matrix

    Science.gov (United States)

    Wang, M.; Hu, J.; Zhou, M.; Li, J. M.; Zhang, Z.

    2013-05-01

    As the linear array sensor has great potential in disaster monitoring, geological survey, the quality of the image geometric correction should be guaranteed. The primary focus of this paper is to present a new method correcting airbone linear image based on the bias matrix,which is bulit by describing and analysing the errors of airbone linear image included the misalignment. The bias matrix was considered as additional observations to the traditional geometric correction model in our method. And by using control points which have both image coordinate and object coordinate, the solving equation from geometric correction model can be established and the bias matrix can be calculated by adjustment strategy. To avoid the singularity problem in the calculating process, this paper uses quaternion to describe the image's attitude and rotation instead of traditional calculating method which is structured by the Euler angle. Finally, geometric correction of airborne linear array image with high accuracy based on bias matrix can be achieved.

  13. Coded aperture imaging with self-supporting uniformly redundant arrays. [Patent application

    Science.gov (United States)

    Fenimore, E.E.

    1980-09-26

    A self-supporting uniformly redundant array pattern for coded aperture imaging. The invention utilizes holes which are an integer times smaller in each direction than holes in conventional URA patterns. A balance correlation function is generated where holes are represented by 1's, nonholes are represented by -1's, and supporting area is represented by 0's. The self-supporting array can be used for low energy applications where substrates would greatly reduce throughput.

  14. Pixel electronic noise as a function of position in an active matrix flat panel imaging array

    Science.gov (United States)

    Yazdandoost, Mohammad Y.; Wu, Dali; Karim, Karim S.

    2010-04-01

    We present an analysis of output referred pixel electronic noise as a function of position in the active matrix array for both active and passive pixel architectures. Three different noise sources for Active Pixel Sensor (APS) arrays are considered: readout period noise, reset period noise and leakage current noise of the reset TFT during readout. For the state-of-the-art Passive Pixel Sensor (PPS) array, the readout noise of the TFT switch is considered. Measured noise results are obtained by modeling the array connections with RC ladders on a small in-house fabricated prototype. The results indicate that the pixels in the rows located in the middle part of the array have less random electronic noise at the output of the off-panel charge amplifier compared to the ones in rows at the two edges of the array. These results can help optimize for clearer images as well as help define the region-of-interest with the best signal-to-noise ratio in an active matrix digital flat panel imaging array.

  15. Spatiotemporal multiplexing: color decoding from single-array digital images

    Science.gov (United States)

    Martinez-Uriegas, Eugenio; Crane, Hewitt D.; Peters, John D.

    1997-06-01

    This is an update from our ongoing studies on a biologically inspired, digital color image representation presented here before. It has evolved into a technology named ChromaplexTM, with practical applications for both static (still pictures) and dynamic (digital video and motion pictures) images in three areas: (1) Simplification of processing, storage, compression, and transmission of digital color images. (2) Economical full-color upgrading of black and white (gray scale) image capturing systems. (3) Increase up to 4X of spatial resolution in high-quality digital image capturing systems currently designed for triplane color capture (three separate CCDs or three scans). Sample images of these applications are available on a world wide web site. In this paper we present data showing that spatial blur artifacts are worse when produced by conventional techniques of color interpolation than those produced by Chromaplex decoding. We also show that Chromaplex color decoding of CCD outputs, first demonstrated for CCDs with relatively narrow-band RGB filters, is equally applicable to digital imaging systems having CCDs with broad band subtractive color filters (like cyan, yellow, and magenta), but the often necessary color transformation from subtractive color to RGB brings in different tradeoffs.

  16. Curvilinear 3-D Imaging Using Row--Column-Addressed 2-D Arrays with a Diverging Lens: Feasibility Study

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Engholm, Mathias; Beers, Christopher

    2017-01-01

    on simulations. A synthetic aperture imaging sequence with single element transmissions is designed for imaging down to 14 cm at a volume rate of 88 Hz. Using a diverging lens with f-number of -1 circumscribing the underlying RCA array, the imaging quality of a double-curved λ/2-pitch 3 MHz 62+62 RCA 2-D array...

  17. High-resolution CCD imagers using area-array CCD's for sensing spectral components of an optical line image

    Science.gov (United States)

    Elabd, Hammam (Inventor); Kosonocky, Walter F. (Inventor)

    1987-01-01

    CCD imagers with a novel replicated-line-imager architecture are abutted to form an extended line sensor. The sensor is preceded by optics having a slit aperture and having an optical beam splitter or astigmatic lens for projecting multiple line images through an optical color-discriminating stripe filter to the CCD imagers. A very high resolution camera suitable for use in a satellite, for example, is thus provided. The replicated-line architecture of the imager comprises an area-array CCD, successive rows of which are illuminated by replications of the same line segment, as transmitted by respective color filter stripes. The charge packets formed by accumulation of photoresponsive charge in the area-array CCD are read out row by row. Each successive row of charge packets is then converted from parallel to serial format in a CCD line register and its amplitude sensed to generate a line of output signal.

  18. Top-orthogonal-to-bottom-electrode (TOBE) CMUT arrays for 3-D ultrasound imaging.

    Science.gov (United States)

    Sampaleanu, Alex; Zhang, Peiyu; Kshirsagar, Abhijeet; Moussa, Walied; Zemp, Roger J

    2014-02-01

    Two-dimensional ultrasound arrays hold great promise for 3-D imaging; however, wiring of each channel becomes impractical for large arrays or for small-footprint catheter probes for which the number of wires must be limited. Capacitive micromachined ultrasound transducers offer a promising solution for such 2-D array applications, but channel routing is still non-trivial. A top-orthogonal-to-bottom-electrode (TOBE) 2-D CMUT array architecture is presented along with row-column addressing schemes for low-channel-count 3-D ultrasound imaging. An N × N TOBE array is capable of obtaining 3-D images using only 2N channels. An interfacing scheme is presented in which transmit-receive signals are routed along rows while bias voltages are applied along columns, effectively allowing for single-element transmit/receive control. Simulations demonstrated potentially finer resolution and improved side lobe suppression over a previously published row-column-based imaging method. Laser vibrometer testing was done to measure membrane displacement in air and confirmed that single-element air-coupled actuation in transmit mode could be achieved using our proposed interfacing scheme. Acoustic testing was also performed in both transmit and receive modes to characterize the ability of the proposed interfacing scheme to achieve dominant-element transmission and reception in immersion operation. It was seen that membrane displacement in both modes was indeed largely confined to the active area.

  19. Cardiac cine imaging at 3 Tesla: initial experience with a 32-element body-array coil.

    Science.gov (United States)

    Fenchel, Michael; Deshpande, Vibhas S; Nael, Kambiz; Finn, J Paul; Miller, Stephan; Ruehm, Stefan; Laub, Gerhard

    2006-08-01

    We sought to assess the feasibility of cardiac cine imaging and evaluate image quality at 3 T using a body-array coil with 32 coil elements. Eight healthy volunteers (3 men; median age 29 years) were examined on a 3-T magnetic resonance scanner (Magnetom Trio, Siemens Medical Solutions) using a 32-element phased-array coil (prototype from In vivo Corp.). Gradient-recalled-echo (GRE) cine (GRAPPAx3), GRE cine with tagging lines, steady-state-free-precession (SSFP) cine (GRAPPAx3 and x4), and SSFP cine(TSENSEx4 andx6) images were acquired in short-axis and 4-chamber view. Reference images with identical scan parameters were acquired using the total-imaging-matrix (Tim) coil system with a total of 12 coil elements. Images were assessed by 2 observers in a consensus reading with regard to image quality, noise and presence of artifacts. Furthermore, signal-to-noise values were determined in phantom measurements. In phantom measurements signal-to-noise values were increased by 115-155% for the various cine sequences using the 32-element coil. Scoring of image quality yielded statistically significant increased image quality with the SSFP-GRAPPAx4, SSFP-TSENSEx4, and SSFP-TSENSEx6 sequence using the 32-element coil (P coil (P coil is feasible in healthy volunteers. Using a large number of coil elements with a favorable sensitivity profile supports faster image acquisition, with high diagnostic image quality even for high parallel imaging factors.

  20. Real-time system for imaging and object detection with a multistatic GPR array

    Energy Technology Data Exchange (ETDEWEB)

    Paglieroni, David W; Beer, N Reginald; Bond, Steven W; Top, Philip L; Chambers, David H; Mast, Jeffrey E; Donetti, John G; Mason, Blake C; Jones, Steven M

    2014-10-07

    A method and system for detecting the presence of subsurface objects within a medium is provided. In some embodiments, the imaging and detection system operates in a multistatic mode to collect radar return signals generated by an array of transceiver antenna pairs that is positioned across the surface and that travels down the surface. The imaging and detection system pre-processes the return signal to suppress certain undesirable effects. The imaging and detection system then generates synthetic aperture radar images from real aperture radar images generated from the pre-processed return signal. The imaging and detection system then post-processes the synthetic aperture radar images to improve detection of subsurface objects. The imaging and detection system identifies peaks in the energy levels of the post-processed image frame, which indicates the presence of a subsurface object.

  1. Hybrid-array-based optoacoustic and ultrasound (OPUS) imaging of biological tissues

    Science.gov (United States)

    Deán-Ben, X. L.; Merčep, E.; Razansky, D.

    2017-05-01

    Hybrid optoacoustic and pulse-echo ultrasound imaging is an attractive multi-modal combination owing to the highly complementary contrast of the two techniques. Efficient hybridization is often hampered by significant dissimilarities between their optimal data acquisition and image formation strategies. Herein, we introduce an approach for combined optoacoustic and ultrasound imaging based on a plano-concave detector array design with a non-uniform pitch distribution. The hybrid design optimized for both modalities allows for maintaining an extended field of view for efficient ultrasound navigation while simultaneously providing broad tomographic coverage for optimal optoacoustic imaging performance. Imaging sessions performed in tissue-mimicking phantoms and healthy volunteers demonstrate that the suggested approach renders an enhanced imaging performance as compared with the previously reported hybrid optoacoustic and ultrasound imaging approaches. Thus, it can greatly facilitate clinical translation of the optoacoustic imaging technology by means of its efficient combination with ultrasonography, a well-established clinical imaging modality.

  2. A novel imaging technique for structural health monitoring using sparse and compact arrays

    Science.gov (United States)

    Masson, Patrice; Quaegebeur, Nicolas; Demers, Dominique L.

    2011-04-01

    In the present paper, a technique called Excitelet is presented for the imaging of damages in thin-walled structures using the correlation of the measured signals with dispersed versions of the excitation signal. Piezoceramic (PZT) actuators are used to generate burst Lamb waves which interact with defects in metallic structures and the measurement is taken using sparse and compact array configurations of PZT sensors. The sparse sensing configuration consists of individual circular PZT elements distributed over the plate while the compact array configuration consists of a linear arrangement of sensors micro-machined on a single piece of bulk PZT wafer. This approach is presented as an extension of the classical imaging techniques and takes advantage of the chirplet-based matching pursuit algorithm. The approach is investigated experimentally on a 1.54 mm thick aluminum plate and comparison with existing Embedded Ultrasonic Structural Radar (EUSR) algorithm is performed for A0 and S0 modes for two frequency ranges of interest (centered at 150 kHz and 550 kHz). Damages are simulated using stacked magnets at different locations on the plate. Significant improvement of imaging quality is demonstrated with respect to existing imaging techniques based on group velocity and Time-of-Flight (ToF), for both sparse and compact PZT array configurations. Multimodal imaging strategies are presented to improve the imaging results. Moreover, it is shown that the proposed imaging technique provide accurate results in the case of dispersive propagation, while existing imaging techniques are no longer applicable.

  3. Volumetric Ultrasound Imaging with Row-Column Addressed 2-D Arrays Using Spatial Matched Filter Beamforming

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Engholm, Mathias; Christiansen, Thomas Lehrmann

    2015-01-01

    For 3-D ultrasound imaging with row-column addressed 2-D arrays, the two orthogonal 1-D transmit and receive arrays are both used for one-way focusing in the lateral and elevation directions separately and since they are not in the same plane, the two-way focusing is the same as one-way focusing...... resolution. The performance is investigated on both simulated and experimentally collected 3-D data by comparing the Point Spread Functions (PSFs) and the phantom images obtained with standard DAS and with SMF. Results show that the SMF beamformer outperforms DAS in both simulated and experimental trials...

  4. Resolution-enhanced integral imaging display using a dense point light source array

    Science.gov (United States)

    Wang, Zi; Wang, Anting; Ma, Xiaohui; Ma, Fenghua; Ming, Hai

    2017-11-01

    A scheme for the resolution enhancement of a dense point light source integral imaging display is proposed. The proposed method uses 9 light emitting diodes (LEDs), a collimating lens and a lens array to generate 4 times more point light sources than elemental lenses constituting the lens array. In consequence, the resolution of the 3D images is enhanced up to 4 times. The viewing angle keeps the same and no crosstalk appears. The principle of the proposed method is described and verified experimentally.

  5. Single photon imaging and timing array sensor apparatus and method

    Science.gov (United States)

    Smith, R. Clayton

    2003-06-24

    An apparatus and method are disclosed for generating a three-dimension image of an object or target. The apparatus is comprised of a photon source for emitting a photon at a target. The emitted photons are received by a photon receiver for receiving the photon when reflected from the target. The photon receiver determines a reflection time of the photon and further determines an arrival position of the photon on the photon receiver. An analyzer is communicatively coupled to the photon receiver, wherein the analyzer generates a three-dimensional image of the object based upon the reflection time and the arrival position.

  6. Terahertz heterodyne technology for astronomy and planetary science

    NARCIS (Netherlands)

    Wild, Wolfgang

    2007-01-01

    Heterodyne detection techniques play an important role in high-resolution spectroscopy in astronomy and planetary science. In particular, heterodyne technology in the Terahertz range has rapidly evolved in recent years. Cryogenically cooled receivers approaching quantum-limited sensitivity have been

  7. Hexabundles: imaging fiber arrays for low-light astronomical applications

    DEFF Research Database (Denmark)

    Bland-Hawthorn, Joss; Bryant, Julia; Robertson, Gordon

    2011-01-01

    We demonstrate for the first time an imaging fibre bundle (“hexabundle”) that is suitable for low-light applications in astronomy. The most successful survey instruments at optical-infrared wavelengths today have obtained data on up to a million celestial sources using hundreds of multimode fibre...

  8. Hexabundles: imaging fibre arrays for low-light astronomical applications

    DEFF Research Database (Denmark)

    Bland-Hawthorn, Joss; Bryant, Julie; Robertson, Gordon

    2010-01-01

    We demonstrate for the first time an imaging fibre bundle (“hexabundle”) that is suitable for low-light applications in astronomy. The most successful survey instruments at optical-infrared wavelengths today have obtained data on up to a million celestial sources using hundreds of multimode fibres...

  9. Algorithms and Array Design Criteria for Robust Imaging in Interferometry

    Science.gov (United States)

    2016-04-01

    Harvard SEAS, and especially to Ms. Kathy Masse and Ms. Lisa Frazier-Zezze. Both Kathy and Lisa were always so pleasant and helpful to me, and I...target selected was NASA’s Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite for which the truth image (Hill, 2008) is

  10. A coherent through-wall MIMO phased array imaging radar based on time-duplexed switching

    Science.gov (United States)

    Chen, Qingchao; Chetty, Kevin; Brennan, Paul; Lok, Lai Bun; Ritchie, Matthiew; Woodbridge, Karl

    2017-05-01

    Through-the-Wall (TW) radar sensors are gaining increasing interest for security, surveillance and search and rescue applications. Additionally, the integration of Multiple-Input, Multiple-Output (MIMO) techniques with phased array radar is allowing higher performance at lower cost. In this paper we present a 4-by-4 TW MIMO phased array imaging radar operating at 2.4 GHz with 200 MHz bandwidth. To achieve high imaging resolution in a cost-effective manner, the 4 Tx and 4 Rx elements are used to synthesize a uniform linear array (ULA) of 16 virtual elements. Furthermore, the transmitter is based on a single-channel 4-element time-multiplexed switched array. In transmission, the radar utilizes frequency modulated continuous wave (FMCW) waveforms that undergo de-ramping on receive to allow digitization at relatively low sampling rates, which then simplifies the imaging process. This architecture has been designed for the short-range TW scenarios envisaged, and permits sufficient time to switch between antenna elements. The paper first outlines the system characteristics before describing the key signal processing and imaging algorithms which are based on traditional Fast Fourier Transform (FFT) processing. These techniques are implemented in LabVIEW software. Finally, we report results from an experimental campaign that investigated the imaging capabilities of the system and demonstrated the detection of personnel targets. Moreover, we show that multiple targets within a room with greater than approximately 1 meter separation can be distinguished from one another.

  11. A Large Aperture UWB Antenna Array for Real Beam Radar Imaging

    Directory of Open Access Journals (Sweden)

    Chao-Hsiang Liao

    2012-01-01

    Full Text Available The development of four-element ultra-wideband (UWB comb taper slot antenna array with 18 cm element spacing for real beam radar imaging is described. The four-element UWB array system with optimum element spacing is analyzed by energy pattern. A wideband double ridge horn antenna is used as the transmitting antenna, the developed large aperture UWB array is used as the receiving antenna. The transmitting antenna and the receiving antenna are combined with impulse time domain measurement system to achieve real beam radar imaging. The receiving impulse signals at various positions are processed by the time delay and sum algorithm. The examples of several aluminum cans have been verified in the resolution and compared with using the UWB array as a receive antenna and the double ridge horn as a transmit antenna in the test setup. The crossrange resolution of UWB antenna array is better than wideband double ridge horn antenna because the beam width of UWB array is narrower.

  12. Experimental Demonstration of Adaptive Infrared Multispectral Imaging using Plasmonic Filter Array

    Science.gov (United States)

    Jang, Woo-Yong; Ku, Zahyun; Jeon, Jiyeon; Kim, Jun Oh; Lee, Sang Jun; Park, James; Noyola, Michael J.; Urbas, Augustine

    2016-10-01

    In our previous theoretical study, we performed target detection using a plasmonic sensor array incorporating the data-processing technique termed “algorithmic spectrometry”. We achieved the reconstruction of a target spectrum by extracting intensity at multiple wavelengths with high resolution from the image data obtained from the plasmonic array. The ultimate goal is to develop a full-scale focal plane array with a plasmonic opto-coupler in order to move towards the next generation of versatile infrared cameras. To this end, and as an intermediate step, this paper reports the experimental demonstration of adaptive multispectral imagery using fabricated plasmonic spectral filter arrays and proposed target detection scenarios. Each plasmonic filter was designed using periodic circular holes perforated through a gold layer, and an enhanced target detection strategy was proposed to refine the original spectrometry concept for spatial and spectral computation of the data measured from the plasmonic array. Both the spectrum of blackbody radiation and a metal ring object at multiple wavelengths were successfully reconstructed using the weighted superposition of plasmonic output images as specified in the proposed detection strategy. In addition, plasmonic filter arrays were theoretically tested on a target at extremely high temperature as a challenging scenario for the detection scheme.

  13. Experimental Demonstration of Adaptive Infrared Multispectral Imaging using Plasmonic Filter Array.

    Science.gov (United States)

    Jang, Woo-Yong; Ku, Zahyun; Jeon, Jiyeon; Kim, Jun Oh; Lee, Sang Jun; Park, James; Noyola, Michael J; Urbas, Augustine

    2016-10-10

    In our previous theoretical study, we performed target detection using a plasmonic sensor array incorporating the data-processing technique termed "algorithmic spectrometry". We achieved the reconstruction of a target spectrum by extracting intensity at multiple wavelengths with high resolution from the image data obtained from the plasmonic array. The ultimate goal is to develop a full-scale focal plane array with a plasmonic opto-coupler in order to move towards the next generation of versatile infrared cameras. To this end, and as an intermediate step, this paper reports the experimental demonstration of adaptive multispectral imagery using fabricated plasmonic spectral filter arrays and proposed target detection scenarios. Each plasmonic filter was designed using periodic circular holes perforated through a gold layer, and an enhanced target detection strategy was proposed to refine the original spectrometry concept for spatial and spectral computation of the data measured from the plasmonic array. Both the spectrum of blackbody radiation and a metal ring object at multiple wavelengths were successfully reconstructed using the weighted superposition of plasmonic output images as specified in the proposed detection strategy. In addition, plasmonic filter arrays were theoretically tested on a target at extremely high temperature as a challenging scenario for the detection scheme.

  14. Comparison of polystyrene scintillator fiber array and monolithic polystyrene for neutron imaging and radiography

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, R., E-mail: raspberry@lanl.gov; Cutler, T. E.; Danly, C. R.; Espy, M. A.; Goglio, J. H.; Hunter, J. F.; Madden, A. C.; Mayo, D. R.; Merrill, F. E.; Nelson, R. O.; Swift, A. L.; Wilde, C. H.; Zocco, T. G. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2016-11-15

    The neutron imaging diagnostic at the National Ignition Facility has been operating since 2011 generating neutron images of deuterium-tritium (DT) implosions at peak compression. The current design features a scintillating fiber array, which allows for high imaging resolution to discern small-scale structure within the implosion. In recent years, it has become clear that additional neutron imaging systems need to be constructed in order to provide 3D reconstructions of the DT source and these additional views need to be on a shorter line of sight. As a result, there has been increased effort to identify new image collection techniques that improve upon imaging resolution for these next generation neutron imaging systems, such as monolithic deuterated scintillators. This work details measurements performed at the Weapons Neutron Research Facility at Los Alamos National Laboratory that compares the radiographic abilities of the fiber scintillator with a monolithic scintillator, which may be featured in a future short line of sight neutron imaging systems.

  15. High-intensity focused ultrasound (HIFU) array system for image-guided ablative therapy (IGAT)

    Science.gov (United States)

    Kaczkowski, Peter J.; Keilman, George W.; Cunitz, Bryan W.; Martin, Roy W.; Vaezy, Shahram; Crum, Lawrence A.

    2003-06-01

    Recent interest in using High Intensity Focused Ultrasound (HIFU) for surgical applications such as hemostasis and tissue necrosis has stimulated the development of image-guided systems for non-invasive HIFU therapy. Seeking an all-ultrasound therapeutic modality, we have developed a clinical HIFU system comprising an integrated applicator that permits precisely registered HIFU therapy delivery and high quality ultrasound imaging using two separate arrays, a multi-channel signal generator and RF amplifier system, and a software program that provides the clinician with a graphical overlay of the ultrasound image and therapeutic protocol controls. Electronic phasing of a 32 element 2 MHz HIFU annular array allows adjusting the focus within the range of about 4 to 12 cm from the face. A central opening in the HIFU transducer permits mounting a commercial medical imaging scanhead (ATL P7-4) that is held in place within a special housing. This mechanical fixture ensures precise coaxial registration between the HIFU transducer and the image plane of the imaging probe. Recent enhancements include development of an acoustic lens using numerical simulations for use with a 5-element array. Our image-guided therapy system is very flexible and enables exploration of a variety of new HIFU therapy delivery and monitoring approaches in the search for safe, effective, and efficient treatment protocols.

  16. Photoacoustic imaging for deep targets in the breast using a multichannel 2D array transducer

    Science.gov (United States)

    Xie, Zhixing; Wang, Xueding; Morris, Richard F.; Padilla, Frederic R.; Lecarpentier, Gerald L.; Carson, Paul L.

    2011-03-01

    A photoacoustic (PA) imaging system was developed to achieve high sensitivity for the detection and characterization of vascular anomalies in the breast in the mammographic geometry. Signal detection from deep in the breast was achieved by a broadband 2D PVDF planar array that has a round shape with one side trimmed straight to improve fit near the chest wall. This array has 572 active elements and a -6dB bandwidth of 0.6-1.7 MHz. The low frequency enhances imaging depth and increases the size of vascular collections displayed without edge enhancement. The PA signals from all the elements go through low noise preamplifiers in the probe that are very close to the array elements for optimized noise control. Driven by 20 independent on-probe signal processing channels, imaging with both high sensitivity and good speed was achieved. To evaluate the imaging depth and the spatial resolution of this system,2.38mm I.D. artificial vessels embedded deeply in ex vivo breasts harvested from fresh cadavers and a 3mm I.D. tube in breast mimicking phantoms made of pork loin and fat tissues were imaged. Using near-infrared laser light with incident energy density within the ANSI safety limit, imaging depths of up to 49 mm in human breasts and 52 mm in phantoms were achieved. With a high power tunable laser working on multiple wavelengths, this system might contribute to 3D noninvasive imaging of morphological and physiological tissue features throughout the breast.

  17. Arrayed liquid crystal microlens based on graphene electrode for imaging application

    Science.gov (United States)

    Hu, Wei; Chen, Cheng; Wu, Yong; Luo, Jun; Lei, Yu; Tong, Qing; Zhang, Xinyu; Xie, Changsheng

    2015-10-01

    In this paper, an arrayed liquid crystal (LC) microlens (ALCM) based on graphene electrode instead of common indium tin oxide (ITO) electrode material is designed and fabricated, and the corresponding testing results have been obtained and presented. The graphene film used as patterned electrode in the project is grown by chemical vapor deposition (CVD) over copper foils, which demonstrate the properties of low sheet resistance and high transmittance of more than 90% in current stage. The key fabrication of the arrayed LC microlens based on graphene electrode includes the graphene transfering, ultraviolet lithography, ICP etching, liquid crystalline polymer encapsulation, etc. In the test of the arrayed LC microlens, the point spread functions (PSF) of incident laser beams with different wavelengths, such as red laser of ~600nm wavelength, and green laser of ~532nm wavelength, have been obtained. In addition, the arrayed LC microlenses are also used in visible light imaging. During the imaging tests, each microlens in the arrayed LC microlens can perform imaging process, independently.

  18. An MF/HF radio array for radio and radar imaging of the ionosphere

    Science.gov (United States)

    Isham, Brett; Gustavsson, Bjorn; Belyey, Vasyl; Bullett, Terrence

    2016-07-01

    The Aguadilla Radio Array will be installed at the Interamerican University Aguadilla Campus, located in northwestern Puerto Rico. The array is intended for broad-band medium and high-frequency (MF/HF, roughly 2 to 25 MHz) radio and bistatic radar observations of the ionosphere. The main array consists of 20 antenna elements, arranged in a semi-random pattern providing a good distribution of baseline vectors, with 6-meter minimum spacing to eliminate spacial aliasing. A relocatable 6-element array is also being developed, in which each element consists of a crossed pair of active electric dipoles and all associated electronics for phase-coherent radio measurements. A primary scientific goal of the array is to create images of the region of ionospheric radio emissions stimulated by the new Arecibo Observatory high-power high-frequency radio transmitter. A second primary goal is the study of ionospheric structure and dynamics via coherent radar imaging of the ionosphere in collaboration with the University of Colorado / NOAA Versatile Interferometric Pulsed Ionospheric Radar (VIPIR), located at the USGS San Juan Observatory in Cayey, Puerto Rico. In addition to ionospheric research in collaboration with the Cayey and Arecibo Observatories, the goals of the project include the development of radio sounding, polarization, interferometry, and imaging techniques, and training of students at the university and high school levels.

  19. Design of a Compact Wideband Antenna Array for Microwave Imaging Applications

    Directory of Open Access Journals (Sweden)

    J. Puskely

    2013-12-01

    Full Text Available In the paper, wideband antenna arrays aimed at microwave imaging applications and SAR applications operating at Ka band were designed. The antenna array feeding network is realized by a low-loss SIW technology. Moreover, we have replaced the large feed network comprised of various T and Y junctions by a simple broadband network of compact size to more reduce losses in the substrate integrated waveguide and also save space on the PCB. The designed power 8-way divider is complemented by a wideband substrate integrated waveguide to a grounded coplanar waveguide transition and directly connected to the antenna elements. The measured results of antenna array are consistent with our simulation. Obtained results of the developed array demonstrated improvement compared to previously developed binary feed networks with microstrip or SIW splitters.

  20. Silicon solid/state linear arrays for multispectral high resolution imaging systems

    Science.gov (United States)

    Thompson, L. L.

    1975-01-01

    Solid-state, electronically scanned, linear detector arrays are now available which can be used in a pushbroom scan mode imaging system for high-resolution multispectral earth resource survey applications. These arrays provide high performance in the visible to near-IR region. Two performance criteria must be assessed in the choice of a detector array: signal-to-noise ratio and spectral response. Consideration of diffraction limitations shows that optics size cannot be significantly reduced by using very low-noise detectors. The required spectral response for a viable detector array should not have spectral ripples that cause a low-level, but significant, error in the detected effective reflectance of the target.

  1. 3-D Ultrasound Imaging Performance of a Row-Column Addressed 2-D Array Transducer: A Measurement Study

    DEFF Research Database (Denmark)

    Rasmussen, Morten Fischer; Jensen, Jørgen Arendt

    2013-01-01

    -lobe levels are higher for the row-column addressed array. The cystic resolution sampled at a relative intensity difference of 20 dB shows a cyst size of 5.00mm for the row-column addressed array and 2.39mm for the fully sampled array. A simulation study is carried out which compares how the imaging quality......A real-time 3-D ultrasound measurement using only 32 elements and 32 emissions is presented. The imaging quality is compared to a conventionally fully addressed array using 1024 elements and 256 emissions. The main-lobe of the measured line spread function is almost identical, but the side...... of the two addressing methods scales with the number of beamforming channels used. It is shown that for any fixed number of active elements, a rowcolumn addressed array achieves a better image quality than fully addressing the array. When using 128 channels, the mainlobe when fully addressing the array...

  2. Two-dimensional photonic-crystal vertical-cavity array for nonlinear optical image processing.

    Science.gov (United States)

    Sievenpiper, D F; Lam, C F; Yablonovitch, E

    1998-04-10

    We investigate the electromagnetic properties of a two-dimensional (2-D) photonic-crystal array of vertical cavities for use in nonlinear optical image processing. We determine the 2-D photonic band structure of the array, and we discuss how it is influenced by the degree of interaction between cavities. We study the properties of defects in the 2-D lattice and show that neighboring cavities interact through their overlapping wave functions. This interaction can be used to produce nearest-neighbor nonlinear Boolean functions such asand, or, and xor, which are useful for optical image processing. We demonstrate the use of 2-D photonic bandgap structures for image processing by removing noise from a sample image with a nearest-neighbor and function.

  3. High-resolution thin "guest-host" micropolarizer arrays for visible imaging polarimetry.

    Science.gov (United States)

    Zhao, Xiaojin; Boussaid, Farid; Bermak, Amine; Chigrinov, Vladimir G

    2011-03-14

    We report a micropolarizer array technology exploiting "guest-host" interactions in liquid crystals for visible imaging polarimetry. We demonstrate high resolution thin micropolarizer arrays with a 5 μm×5 μm pixel pitch and a thickness of 0.95 μm. With the "host" nematic liquid crystal molecules photo-aligned by sulfonic azo-dye SD1, we report averaged major principal transmittance, polarization efficiency and order parameter of 80.3%, 0.863 and 0.848, respectively across the 400 nm-700 nm visible spectrum range. The proposed fabrication technology completely removes the need for any selective etching during the fabrication/integration process of the micropolarizer array. Fully CMOS compatible, it is simple and cost-effective, requiring only spin-coating followed by a single ultraviolet-exposure through a "photoalignment master". This makes it well suited to low cost polarization imaging applications.

  4. Full-field heterodyne dynamic interferometry based on hertz-level low differential-frequency acousto-optic frequency shifter

    Science.gov (United States)

    Wu, Zhou; Zhang, Wenxi; Xiangli, Bin; Kong, Xinxin

    2017-06-01

    High precision measurement of optical elements with long focal length is affected by vibration, airflow and other environmental factors due to the long cavity length, which has been difficulty and hot issue in optical machining and detection. In order to overcome the difficulties of high precision measurement of optical elements with long focal length, the paper proposes a full-field heterodyne interferometric measurement technique that could effectively suppress the environmental interference. In the early related research, a series of Hertz-level high-stability, low-differential frequency acousto-optic frequency shifters were successfully developed, which could be applied to heterodyne interferometry, instead of traditional phase-shifting intererometry. On this basis, a full-field heterodyne interference measurement system is developed, using array detector with conventional frame rate for full-field detection, to solve the problem of different optical paths of reference light and measuring light in dynamic interferometers. It could effectively suppress the vibration, noise, airflow and other factors, and thus significantly improve measurement accuracy and environmental adaptability. In typical environment with vibration and airflow, our measurement system can achieve technical indicators as follows: surface measurement accuracy is better than λ/1000 and repeated measurement accuracy is better than 5λ/10000. Thereby the new full-field heterodyne interferometry could be applied to dynamic measurement of large-diameter optical components and systems quality inspection, system installation correction, on-line measurement and other areas.

  5. Wideband 2D array design optimization with fabrication constraints for 3D US imaging.

    Science.gov (United States)

    Roux, Emmanuel; Ramalli, Alessandro; Herve, Liebgott; Cachard, Christian; Robini, Marc; Tortoli, Piero

    2016-10-03

    Ultrasound two-dimensional (2D) arrays are raising increasing interest for their electronic steering capability to investigate three-dimensional (3D) regions without requiring any probe movement. These arrays are typically populated by thousands of elements that, ideally, should be individually driven by the companion scanner. Since this is not convenient, the so-called microbeamforming methods, yielding a pre-beamforming stage performed in the probe handle by suitable custom integrated circuits, have been so far implemented in a few commercial high-end scanners. A possible approach to implement relatively cheap and efficient 3D ultrasound imaging systems is using 2D sparse arrays in which a limited number of elements can be coupled to an equal number of independent transmit/receive channels. In order to obtain ultrasound beams with adequate characteristics all over the investigated volume, the layout of such arrays must be carefully designed. This paper provides guidelines to design, by using simulated annealing optimization, 2D sparse arrays capable of fitting specific applications or fabrication/implementation constraints. In particular, an original energy function based on multi-depth 3D analysis of the beam pattern is also exploited. A tutorial example is given, addressed to find the �������� elements which should be activated in a 2D fully populated array to yield efficient acoustic radiating performance over the entire volume. The proposed method is applied to a 32x32 array centered at 3 MHz to select the 128, 192 and 256 elements that provide the best acoustic performance. It is shown that the 256-element optimized array yields sidelobe levels even lower (by 5.7 dB) than that of the reference 716-element circular and (by 10.3 dB) than that of the reference 1024-element array.

  6. Ontology-based, Tissue MicroArray oriented, image centered tissue bank

    Directory of Open Access Journals (Sweden)

    Viti Federica

    2008-04-01

    Full Text Available Abstract Background Tissue MicroArray technique is becoming increasingly important in pathology for the validation of experimental data from transcriptomic analysis. This approach produces many images which need to be properly managed, if possible with an infrastructure able to support tissue sharing between institutes. Moreover, the available frameworks oriented to Tissue MicroArray provide good storage for clinical patient, sample treatment and block construction information, but their utility is limited by the lack of data integration with biomolecular information. Results In this work we propose a Tissue MicroArray web oriented system to support researchers in managing bio-samples and, through the use of ontologies, enables tissue sharing aimed at the design of Tissue MicroArray experiments and results evaluation. Indeed, our system provides ontological description both for pre-analysis tissue images and for post-process analysis image results, which is crucial for information exchange. Moreover, working on well-defined terms it is then possible to query web resources for literature articles to integrate both pathology and bioinformatics data. Conclusions Using this system, users associate an ontology-based description to each image uploaded into the database and also integrate results with the ontological description of biosequences identified in every tissue. Moreover, it is possible to integrate the ontological description provided by the user with a full compliant gene ontology definition, enabling statistical studies about correlation between the analyzed pathology and the most commonly related biological processes.

  7. Chemical imaging of cotton fibers using an infrared microscope and a focal-plane array detector

    Science.gov (United States)

    In this presentation, the chemical imaging of cotton fibers with an infrared microscope and a Focal-Plane Array (FPA) detector will be discussed. Infrared spectroscopy can provide us with information on the structure and quality of cotton fibers. In addition, FPA detectors allow for simultaneous spe...

  8. A Custom-Made Linear Array Transducer for Photoacoustic Breast Imaging

    NARCIS (Netherlands)

    Xia, W.; Piras, D.; Heijblom, M.; van Hespen, Johannes C.G.; van Veldhoven, S.; Prins, C; van Leeuwen, Ton; Steenbergen, Wiendelt; Manohar, Srirang

    2012-01-01

    A custom-made first prototype of a linear array ultrasound transducer for breast imaging is presented. Large active area transducer elements (5 mm × 5 mm) with 1 MHz resonance frequency are chosen to obtain a relatively high sensitivity. Acoustic lenses are used to enlarge the narrow acceptance

  9. Mercuric iodide room-temperature array detectors for gamma-ray imaging

    Energy Technology Data Exchange (ETDEWEB)

    Patt, B. [Xsirius, Inc, Camarillo, CA (United States)

    1994-11-15

    Significant progress has been made recently in the development of mercuric iodide detector arrays for gamma-ray imaging, making real the possibility of constructing high-performance small, light-weight, portable gamma-ray imaging systems. New techniques have been applied in detector fabrication and then low noise electronics which have produced pixel arrays with high-energy resolution, high spatial resolution, high gamma stopping efficiency. Measurements of the energy resolution capability have been made on a 19-element protypical array. Pixel energy resolutions of 2.98% fwhm and 3.88% fwhm were obtained at 59 keV (241-Am) and 140-keV (99m-Tc), respectively. The pixel spectra for a 14-element section of the data is shown together with the composition of the overlapped individual pixel spectra. These techniques are now being applied to fabricate much larger arrays with thousands of pixels. Extension of these principles to imaging scenarios involving gamma-ray energies up to several hundred keV is also possible. This would enable imaging of the 208 keV and 375-414 keV 239-Pu and 240-Pu structures, as well as the 186 keV line of 235-U.

  10. Demonstration of nanoimprinted hyperlens array for high-throughput sub-diffraction imaging

    Science.gov (United States)

    Byun, Minsueop; Lee, Dasol; Kim, Minkyung; Kim, Yangdoo; Kim, Kwan; Ok, Jong G.; Rho, Junsuk; Lee, Heon

    2017-04-01

    Overcoming the resolution limit of conventional optics is regarded as the most important issue in optical imaging science and technology. Although hyperlenses, super-resolution imaging devices based on highly anisotropic dispersion relations that allow the access of high-wavevector components, have recently achieved far-field sub-diffraction imaging in real-time, the previously demonstrated devices have suffered from the extreme difficulties of both the fabrication process and the non-artificial objects placement. This results in restrictions on the practical applications of the hyperlens devices. While implementing large-scale hyperlens arrays in conventional microscopy is desirable to solve such issues, it has not been feasible to fabricate such large-scale hyperlens array with the previously used nanofabrication methods. Here, we suggest a scalable and reliable fabrication process of a large-scale hyperlens device based on direct pattern transfer techniques. We fabricate a 5 cm × 5 cm size hyperlenses array and experimentally demonstrate that it can resolve sub-diffraction features down to 160 nm under 410 nm wavelength visible light. The array-based hyperlens device will provide a simple solution for much more practical far-field and real-time super-resolution imaging which can be widely used in optics, biology, medical science, nanotechnology and other closely related interdisciplinary fields.

  11. Primary gamma ray selection in a hybrid timing/imaging Cherenkov array

    Directory of Open Access Journals (Sweden)

    Postnikov E.B.

    2017-01-01

    Full Text Available This work is a methodical study on hybrid reconstruction techniques for hybrid imaging/timing Cherenkov observations. This type of hybrid array is to be realized at the gamma-observatory TAIGA intended for very high energy gamma-ray astronomy (> 30 TeV. It aims at combining the cost-effective timing-array technique with imaging telescopes. Hybrid operation of both of these techniques can lead to a relatively cheap way of development of a large area array. The joint approach of gamma event selection was investigated on both types of simulated data: the image parameters from the telescopes, and the shower parameters reconstructed from the timing array. The optimal set of imaging parameters and shower parameters to be combined is revealed. The cosmic ray background suppression factor depending on distance and energy is calculated. The optimal selection technique leads to cosmic ray background suppression of about 2 orders of magnitude on distances up to 450 m for energies greater than 50 TeV.

  12. Push-broom imaging spectrometer based on planar lightwave circuit MZI array

    Science.gov (United States)

    Yang, Minyue; Li, Mingyu; He, Jian-Jun

    2017-05-01

    We propose a large aperture static imaging spectrometer (LASIS) based on planar lightwave circuit (PLC) MZI array. The imaging spectrometer works in the push-broom mode with the spectrum performed by interferometry. While the satellite/aircraft is orbiting, the same source, seen from the satellite/aircraft, moves across the aperture and enters different MZIs, while adjacent sources enter adjacent MZIs at the same time. The on-chip spectrometer consists of 256 input mode converters, followed by 256 MZIs with linearly increasing optical path delays and a detector array. Multiple chips are stick together to form the 2D image surface and receive light from the imaging lens. Two MZI arrays are proposed, one works in wavelength ranging from 500nm to 900nm with SiON(refractive index 1.6) waveguides and another ranging from 1100nm to 1700nm with SOI platform. To meet the requirements of imaging spectrometer applications, we choose large cross-section ridge waveguide to achieve polarization insensitive, maintain single mode propagation in broad spectrum and increase production tolerance. The SiON on-chip spectrometer has a spectral resolution of 80cm-1 with a footprint of 17×15mm2 and the SOI based on-chip spectrometer has a resolution of 38cm-1 with a size of 22×19mm2. The spectral and space resolution of the imaging spectrometer can be further improved by simply adding more MZIs. The on-chip waveguide MZI array based Fourier transform imaging spectrometer can provide a highly compact solution for remote sensing on unmanned aerial vehicles or satellites with advantages of small size, light weight, no moving parts and large input aperture.

  13. 7 Tesla 22-channel wrap-around coil array for cervical spinal cord and brainstem imaging.

    Science.gov (United States)

    Zhang, Bei; Seifert, Alan C; Kim, Joo-Won; Borrello, Joseph; Xu, Junqian

    2017-10-01

    Increased signal-to-noise ratio and blood oxygenation level-dependent sensitivity at 7 Tesla (T) have the potential to enable high-resolution imaging of the human cervical spinal cord and brainstem. We propose a new two-panel radiofrequency coil design for these regions to fully exploit the advantages of ultra-high field. A two-panel array, containing four transmit/receive and 18 receive-only elements fully encircling the head and neck, was constructed following simulations demonstrating the B1+ and specific absorption rate (SAR) benefits of two-panel over one-panel arrays. This array was compared with a previously reported posterior-only array and tested for safety using a phantom. Its anatomical, functional, and diffusion MRI performance was demonstrated in vivo. The two-panel array produced more uniform B1+ across the brainstem and cervical spinal cord without compromising SAR, and achieved 70% greater receive sensitivity than the posterior-only array. The two-panel design enabled acceleration of R = 2 × 2 in two dimensions or R = 3 in a single dimension. High quality in vivo anatomical, functional, and diffusion images of the human cervical spinal cord and brainstem were acquired. We have designed and constructed a wrap-around coil array with excellent performance for cervical spinal cord and brainstem MRI at 7T, which enables simultaneous human cervical spinal cord and brainstem functional MRI. Magn Reson Med 78:1623-1634, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  14. 640x512 InGaAs focal plane array camera for visible and SWIR imaging

    Science.gov (United States)

    Martin, Tara; Brubaker, Robert; Dixon, Peter; Gagliardi, Mari-Anne; Sudol, Tom

    2005-05-01

    We report on our 640x512 pixel InGaAs/InP focal plane array camera for visible and short-wavelength infrared imaging. For this camera, we have fabricated a 640x512 element substrate-removed backside-illuminated InGaAs/InP photodiode array (PDA) with a 25 mm pixel pitch. The PDA is indium bump bonded to a silicon read out integrated circuit. Removing the InP substrate from the focal plane array allows visible wavelengths, which would otherwise be absorbed by the InP substrate due to its 920 nm wavelength cut-off, to reach the pixels' active region. The quantum efficiency is approximately 15% at 500 nm, 70% at 850 nm, 85% at 1310 nm, and 80% at 1550 nm. Features incorporated into this video-rate, 14-bit output camera include external triggering, windowing, individual pixel correction, 8 operational settings of gain and exposure time, and gamma correction. The readout circuit uses a gate-modulated pixel for high sensitivity imaging over a wide illumination range. This camera is useable for visible imaging as well as imaging eye-safe lasers and is of particular interest seeing laser designators and night vision as well as hyperspectral imaging.

  15. A Nested Phosphorus and Proton Coil Array for Brain Magnetic Resonance Imaging and Spectroscopy

    Science.gov (United States)

    Brown, Ryan; Lakshmanan, Karthik; Madelin, Guillaume; Parasoglou, Prodromos

    2015-01-01

    A dual-nuclei radiofrequency coil array was constructed for phosphorus and proton magnetic resonance imaging and spectroscopy of the human brain at 7 Tesla. An eight-channel transceive degenerate birdcage phosphorus module was implemented to provide whole-brain coverage and significant sensitivity improvement over a standard dual-tuned loop coil. A nested eight-channel proton module provided adequate sensitivity for anatomical localization without substantially sacrificing performance on the phosphorus module. The developed array enabled phosphorus spectroscopy, a saturation transfer technique to calculate the global creatine kinase forward reaction rate, and single-metabolite whole-brain imaging with 1.4 cm nominal isotropic resolution in 15 min (2.3 cm actual resolution), while additionally enabling 1 mm isotropic proton imaging. This study demonstrates that a multi-channel array can be utilized for phosphorus and proton applications with improved coverage and/or sensitivity over traditional single-channel coils. The efficient multi-channel coil array, time-efficient pulse sequences, and the enhanced signal strength available at ultra-high fields can be combined to allow volumetric assessment of the brain and could provide new insights into the underlying energy metabolism impairment in several neurodegenerative conditions, such as Alzheimer’s and Parkinson’s diseases, as well as mental disorders such as schizophrenia. PMID:26375209

  16. Light intensity and SNR improvement for high-resolution optical imaging via time multiplexed pinhole arrays.

    Science.gov (United States)

    Schwarz, Ariel; Shemer, Amir; Zalevsky, Zeev

    2014-07-10

    In this paper, we present a novel method for pinhole optics with variable pinhole arrays. The imaging system is based on a time multiplexing method using variable and moving pinhole arrays. The improved resolution and signal-to-noise ratio are achieved with improved light intensity in the same exposure time, compared with that of a one-pinhole system. This new configuration preserves the advantages of pinhole optics while solving the resolution limitation problem and the long exposure time of such systems. The system also can be used as an addition to several existing optical systems, which use visible and invisible light and x-ray systems.

  17. Application of conformal map theory for design of 2-D ultrasonic array structure for NDT imaging application: a feasibility study.

    Science.gov (United States)

    Ramadas, Sivaram N; Jackson, Joseph C; Dziewierz, Jerzy; O'Leary, Richard; Gachagan, Anthony

    2014-03-01

    Two-dimensional ultrasonic phased arrays are becoming increasingly popular in nondestructive evaluation (NDE). Sparse array element configurations are required to fully exploit the potential benefits of 2-D phased arrays. This paper applies the conformal mapping technique as a means of designing sparse 2-D array layouts for NDE applications. Modeling using both Huygens' field prediction theory and 2-D fast Fourier transformation is employed to study the resulting new structure. A conformal power map was used that, for fixed beam width, was shown in simulations to have a greater contrast than rectangular or random arrays. A prototype aperiodic 2-D array configuration for direct contact operation in steel, with operational frequency ~3 MHz, was designed using the array design principle described in this paper. Experimental results demonstrate a working sparse-array transducer capable of performing volumetric imaging.

  18. Image scanning fluorescence emission difference microscopy based on a detector array.

    Science.gov (United States)

    Li, Y; Liu, S; Liu, D; Sun, S; Kuang, C; Ding, Z; Liu, X

    2017-06-01

    We propose a novel imaging method that enables the enhancement of three-dimensional resolution of confocal microscopy significantly and achieve experimentally a new fluorescence emission difference method for the first time, based on the parallel detection with a detector array. Following the principles of photon reassignment in image scanning microscopy, images captured by the detector array were arranged. And by selecting appropriate reassign patterns, the imaging result with enhanced resolution can be achieved with the method of fluorescence emission difference. Two specific methods are proposed in this paper, showing that the difference between an image scanning microscopy image and a confocal image will achieve an improvement of transverse resolution by approximately 43% compared with that in confocal microscopy, and the axial resolution can also be enhanced by at least 22% experimentally and 35% theoretically. Moreover, the methods presented in this paper can improve the lateral resolution by around 10% than fluorescence emission difference and 15% than Airyscan. The mechanism of our methods is verified by numerical simulations and experimental results, and it has significant potential in biomedical applications. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  19. A Full Parallel Event Driven Readout Technique for Area Array SPAD FLIM Image Sensors.

    Science.gov (United States)

    Nie, Kaiming; Wang, Xinlei; Qiao, Jun; Xu, Jiangtao

    2016-01-27

    This paper presents a full parallel event driven readout method which is implemented in an area array single-photon avalanche diode (SPAD) image sensor for high-speed fluorescence lifetime imaging microscopy (FLIM). The sensor only records and reads out effective time and position information by adopting full parallel event driven readout method, aiming at reducing the amount of data. The image sensor includes four 8 × 8 pixel arrays. In each array, four time-to-digital converters (TDCs) are used to quantize the time of photons' arrival, and two address record modules are used to record the column and row information. In this work, Monte Carlo simulations were performed in Matlab in terms of the pile-up effect induced by the readout method. The sensor's resolution is 16 × 16. The time resolution of TDCs is 97.6 ps and the quantization range is 100 ns. The readout frame rate is 10 Mfps, and the maximum imaging frame rate is 100 fps. The chip's output bandwidth is 720 MHz with an average power of 15 mW. The lifetime resolvability range is 5-20 ns, and the average error of estimated fluorescence lifetimes is below 1% by employing CMM to estimate lifetimes.

  20. A general approach to low noise readout of terahertz imaging arrays.

    Science.gov (United States)

    Chisum, Jonathan D; Grossman, Erich N; Popović, Zoya

    2011-06-01

    This article describes the theory and design of an ultra-low noise electronic readout circuit for use with room temperature video-rate terahertz imaging arrays. First, the noise characteristics of various imaging detectors, including low resistance bolometers and high resistance diodes are discussed. Theoretical approaches to white and 1/f noise mitigation are examined, and a corresponding low-noise readout circuit is designed, built, and tested. It is shown that the circuit is capable of achieving detector limited noise performance for use in room temperature terahertz imaging systems. A thorough noise analysis of the circuit provides the necessary information for applying the readout circuit to any type of imaging detector, and more generally, any measurement of small signals from various source impedances in the presence of white and 1/f noise. W-band measurements of an 8-element, high-resistance detector array, and a 32-element, low-resistance detector array demonstrate the usefulness of the readout circuit. Finally, recommended circuit configurations for various detectors in the literature are provided, with theoretical performance metrics summarized. © 2011 American Institute of Physics

  1. Self-mixing imaging sensor using a monolithic VCSEL array with parallel readout.

    Science.gov (United States)

    Lim, Yah Leng; Nikolic, Milan; Bertling, Karl; Kliese, Russell; Rakić, Aleksandar D

    2009-03-30

    The advent of two-dimensional arrays of Vertical-Cavity Surface-Emitting Lasers (VCSELs) opened a range of potential sensing applications for nanotechnology and life-sciences. With each laser independently addressable, there is scope for the development of high-resolution full-field imaging systems with electronic scanning. We report on the first implementation of a self-mixing imaging system with parallel readout based on a monolithic VCSEL array. A self-mixing Doppler signal was acquired from the variation in VCSEL junction voltage rather than from a conventional variation in laser power, thus markedly reducing the system complexity. The sensor was validated by imaging the velocity distribution on the surface of a rotating disc. The results obtained demonstrate that monolithic arrays of Vertical-Cavity lasers present a powerful tool for the advancement of self-mixing sensors into parallel imaging paradigms and provide a stepping stone to the implementation of a full-field self-mixing sensor systems.

  2. A Full Parallel Event Driven Readout Technique for Area Array SPAD FLIM Image Sensors

    Directory of Open Access Journals (Sweden)

    Kaiming Nie

    2016-01-01

    Full Text Available This paper presents a full parallel event driven readout method which is implemented in an area array single-photon avalanche diode (SPAD image sensor for high-speed fluorescence lifetime imaging microscopy (FLIM. The sensor only records and reads out effective time and position information by adopting full parallel event driven readout method, aiming at reducing the amount of data. The image sensor includes four 8 × 8 pixel arrays. In each array, four time-to-digital converters (TDCs are used to quantize the time of photons’ arrival, and two address record modules are used to record the column and row information. In this work, Monte Carlo simulations were performed in Matlab in terms of the pile-up effect induced by the readout method. The sensor’s resolution is 16 × 16. The time resolution of TDCs is 97.6 ps and the quantization range is 100 ns. The readout frame rate is 10 Mfps, and the maximum imaging frame rate is 100 fps. The chip’s output bandwidth is 720 MHz with an average power of 15 mW. The lifetime resolvability range is 5–20 ns, and the average error of estimated fluorescence lifetimes is below 1% by employing CMM to estimate lifetimes.

  3. Measuring ultra-sonic in-plane vibrations with the scanning confocal heterodyne interferometer

    Science.gov (United States)

    Rembe, C.; Ur-Rehman, F.; Heimes, F.; Boedecker, S.; Dräbenstedt, A.

    2010-05-01

    The advanced progress in miniaturization technologies of mechanical systems and structures has led to a growing demand of measurement tools for three-dimensional vibrations at ultra-high frequencies. Particularly radio-frequency, micro-electro-mechanical (RF-MEM) technology is a planar technology and, thus, the resonating structures are much larger in lateral dimensions compared to the height. Consequently, most ultra-high-frequency devices have larger inplane vibration amplitudes than out-of-plane amplitudes. Recently, we have presented a heterodyne interferometer for vibration frequencies up to 1.2 GHz. In this paper we demonstrate a new method to extract broad-bandwidth spectra of in-plane vibrations with our new heterodyne interferometer. To accomplish this goal we have combined heterodyne interferometry, scanning vibrometry, edge-knife technique, amplitude demodulation, and digital-image processing. With our experimental setup we can realize in-plane vibration measurements up to 600 MHz. We will also show our first measurements of a broad-bandwidth, in-plane vibration around 200 MHz. Our in-plane and out-of-plane vibration measurements are phase-correlated and, therefore, our technique is suitable for broad-bandwidth, full-3D vibration measurements of ultrasonic microdevices.

  4. Image-guided ultrasound phased arrays are a disruptive technology for non-invasive therapy

    Science.gov (United States)

    Hynynen, Kullervo; Jones, Ryan M.

    2016-09-01

    Focused ultrasound offers a non-invasive way of depositing acoustic energy deep into the body, which can be harnessed for a broad spectrum of therapeutic purposes, including tissue ablation, the targeting of therapeutic agents, and stem cell delivery. Phased array transducers enable electronic control over the beam geometry and direction, and can be tailored to provide optimal energy deposition patterns for a given therapeutic application. Their use in combination with modern medical imaging for therapy guidance allows precise targeting, online monitoring, and post-treatment evaluation of the ultrasound-mediated bioeffects. In the past there have been some technical obstacles hindering the construction of large aperture, high-power, densely-populated phased arrays and, as a result, they have not been fully exploited for therapy delivery to date. However, recent research has made the construction of such arrays feasible, and it is expected that their continued development will both greatly improve the safety and efficacy of existing ultrasound therapies as well as enable treatments that are not currently possible with existing technology. This review will summarize the basic principles, current statures, and future potential of image-guided ultrasound phased arrays for therapy.

  5. Image-guided ultrasound phased arrays are a disruptive technology for non-invasive therapy

    Science.gov (United States)

    Hynynen, Kullervo; Jones, Ryan M.

    2016-01-01

    Focused ultrasound offers a non-invasive way of depositing acoustic energy deep into the body, which can be harnessed for a broad spectrum of therapeutic purposes, including tissue ablation, the targeting of therapeutic agents, and stem cell delivery. Phased array transducers enable electronic control over the beam geometry and direction, and can be tailored to provide optimal energy deposition patterns for a given therapeutic application. Their use in combination with modern medical imaging for therapy guidance allows precise targeting, online monitoring, and post-treatment evaluation of the ultrasound-mediated bioeffects. In the past there have been some technical obstacles hindering the construction of large aperture, high-power, densely-populated phased arrays and, as a result, they have not been fully exploited for therapy delivery to date. However, recent research has made the construction of such arrays feasible, and it is expected that their continued development will both greatly improve the safety and efficacy of existing ultrasound therapies as well as enable treatments that are not currently possible with existing technology. This review will summarize the basic principles, current statures, and future potential of image-guided ultrasound phased arrays for therapy. PMID:27494561

  6. 3-D Imaging Using Row-Column-Addressed Arrays With Integrated Apodization

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Rasmussen, Morten Fischer; Bagge, Jan Peter

    2015-01-01

    This paper demonstrates the fabrication, characterization, and experimental imaging results of a 62+62 element λ/2-pitch row-column-addressed capacitive micromachined ultrasonic transducer (CMUT) array with integrated apodization. A new fabrication process was used to manufacture a 26.3 mm by 26.......3 mm array using five lithography steps. The array includes an integrated apodization, presented in detail in Part I of this paper, which is designed to reduce the amplitude of the ghost echoes that are otherwise prominent for row-column-addressed arrays. Custom front-end electronics were produced......Pa, and the sensitivity was 0.299 ± 0.090 V/Pa. The nearest neighbor crosstalk level was -23.9 ± 3.7 dB, while the transmit-to-receive-elements crosstalk level was -40.2 ± 3.5 dB. Imaging of a 0.3-mm-diameter steel wire using synthetic transmit focusing with 62 single-element emissions demonstrated axial and lateral...

  7. Fabrication and Performance of a Miniaturized and Integrated Endoscope Ultrasound Convex Array for Digestive Tract Imaging.

    Science.gov (United States)

    Peng, Jue; Peng, Xiaojian; Tang, Hu; Li, Xiaozhen; Chen, Ruimin; Li, Yang; Wang, Tianfu; Chen, Siping; Shung, Koping; Zhou, Qifa

    2017-04-24

    This work presents the design, fabrication and testing of a miniaturized and integrated ultrasound endoscope for use as an in situ digestive diagnostic device to facilitate real-time ultrasound guidance of intervention treatments. We designed an optimal structure to integrate an auto-focus 5-megapixel camera module with an 8-MHz, 64-element curvilinear ultrasonic array in one miniaturized package. A novel three-axis auto-focusing voice coil motor (VCM) was designed and manufactured for the camera module to move the lens position for auto-focusing and to adjust the lens tilt. The results showed that the array had a center frequency of 8.09 MHz and a -6-dB fractional bandwidth of 83%. At the center frequency, the two-way insertion loss was 40.6 dB. Endoscopic ultrasound imaging demonstrated satisfactory performance for imaging an anthropomorphic phantom of the esophagus. By slightly adjusting the tilt angle of the optical axis of the lens, the optical image captured by the auto-focusing lens obtained improved definition regardless of changes in the view angle of the camera with respect to the objects being captured. The integrated convex ultrasound endoscope, possessing minimal size, improved optical imaging definition, and good ultrasound imaging performance, can become a useful tool in digestive tract imaging. The miniaturized and integrated convex ultrasound endoscope can facilitate real-time ultrasound intervention guidance, reducing risks associated with the operation.

  8. Spectral imaging of O(2) infrared atmospheric airglow with an InGaAs array detector.

    Science.gov (United States)

    Doushkina, V V; Wiens, R H; Thomas, P J; Peterson, R N; Shepherd, G G

    1996-11-01

    A linear InGaAs array was used in an interference filter spectral imager to monitor the twilight decay of the O(2) Infrared Atmospheric (0-1) band in the twilight airglow. The interference filter was centered at 1.582 μm and had a bandwidth (full width at half-maximum) of 1.0 nm. The imaging lens was a simple doublet, and a Fresnel lens was used for smearing any possible sky inhomogeneities. Spectra measured over Toronto in October 1994 show that the sensitivity and spectral discrimination against the contaminating OH spectrum are potentially sufficient to infer meaningful rotational temperatures. The improvements that would result from an area InGaAs array are discussed.

  9. Sparse Array Imaging of Change-Detected Ultrasonic Signals by Minimum Variance Processing

    Science.gov (United States)

    Michaels, J. E.; Hall, J. S.; Hickman, G.; Krolik, J.

    2009-03-01

    Spatially distributed arrays of permanently attached ultrasonic sensors are being considered for structural health monitoring systems. Most algorithms for analyzing the received signals are based upon change detection whereby baselines from the undamaged structure are subtracted from current signals of interest, and the residual signals are analyzed. In particular, delay-and-sum algorithms applied to the residual signals have been shown to be effective for imaging damage in plate-like structures that support propagation of guided waves. Here we consider minimum variance processing of the residual signals, which is an adaptive beamforming method in common use for processing of radar signals where the weights are adjusted at each pixel location prior to summation based upon actual and expected signal amplitudes. Experimental results from a sparse sensor array show that this processing method can provide a significantly improved signal-to-noise ratio by suppressing unwanted sidelobes in the image.

  10. Two-dimensional Fast ESPRIT Algorithm for Linear Array SAR Imaging

    Directory of Open Access Journals (Sweden)

    Zhao Yi-chao

    2015-10-01

    Full Text Available The linear array Synthetic Aperture Radar (SAR system is a popular research tool, because it can realize three-dimensional imaging. However, owning to limitations of the aircraft platform and actual conditions, resolution improvement is difficult in cross-track and along-track directions. In this study, a twodimensional fast Estimation of Signal Parameters by Rotational Invariance Technique (ESPRIT algorithm for linear array SAR imaging is proposed to overcome these limitations. This approach combines the Gerschgorin disks method and the ESPRIT algorithm to estimate the positions of scatterers in cross and along-rack directions. Moreover, the reflectivity of scatterers is obtained by a modified pairing method based on “region growing”, replacing the least-squares method. The simulation results demonstrate the applicability of the algorithm with high resolution, quick calculation, and good real-time response.

  11. Phased-array intracardiac echocardiographic imaging of acute cardiovascular emergencies: Experimental studies in dogs.

    Science.gov (United States)

    Yamada, Elina; Zhang, Yi; Davies, Ray; Coddington, William; Kerber, Richard E

    2002-10-01

    We evaluated a newly developed phased-array intracardiac echocardiographic catheter. Our aim was to evaluate the imaging capability of this new ICE catheter in an animal model simulating acute cardiovascular abnormalities. ICE images were obtained from the right atrium during (1) acute left ventricular dysfunction; (2) acute coronary occlusion; (3) pericardial effusion and tamponade; and (4) pulmonary embolism. Left ventricular dysfunction, induced experimentally by halothane inhalation, resulted in a fall in echocardiography-calculated ejection fraction from 47% +/- 11% to 25% +/- 10%, P small as 15 mL. Right ventricular and atrial compression and respiratory variation in right ventricular inflow during tamponade were demonstrated. After injection of intravenous thrombin to create venous thromboembolism, we demonstrated right ventricular dilatation and dysfunction and thrombi attached to the tricuspid and pulmonary valves and in the pulmonary artery. This new phased-array ICE catheter may be a useful clinical tool for the diagnosis of heart failure, ischemia, tamponade, and pulmonary embolism.

  12. Four-state discrimination scheme beyond the heterodyne limit

    DEFF Research Database (Denmark)

    Muller, C. R.; Castaneda, Mario A. Usuga; Wittmann, C.

    2012-01-01

    We propose and experimentally demonstrate a hybrid discrimination scheme for the quadrature phase shift keying protocol, which outperforms heterodyne detection for any signal power. The discrimination is composed of a quadrature measurement, feed forward and photon detection.......We propose and experimentally demonstrate a hybrid discrimination scheme for the quadrature phase shift keying protocol, which outperforms heterodyne detection for any signal power. The discrimination is composed of a quadrature measurement, feed forward and photon detection....

  13. Ultraviolet photodetectors and imaging arrays based on III-V nitride heterostructures

    Science.gov (United States)

    Brown, Jeffrey David

    2000-10-01

    The III-V nitride class of compound semiconductors has received much attention in the last decade. These materials have a wide, direct bandgap, making them a prime candidate for optoelectronic devices in the blue, green, and ultraviolet spectral regions. These materials exhibit impressive optical, electrical, and thermal properties, even though there are fundamental materials issues that are thus far unresolved. This work explores the application of III-V nitride semiconductors to optical detectors in the ultraviolet region of the electromagnetic spectrum. Metalorganic vapor phase epitaxy was used to synthesize thin film p-i-n photodiode structures on double side polished sapphire substrates; these films were characterized for optical, electrical and structural properties. The grown structures were designed to respond to a predetermined region of the UV spectrum when illuminated from the substrate side. These structures were fabricated into devices using generally accepted techniques for dry etching and p and n-contact metallizations. Test devices were characterized using tools developed by the author. These devices demonstrated as high as 80% quantum efficiency and extremely low dark currents; resulting in spectral detectivities as large as 6 * 1013 cmHz1/2W-1. Devices were designed and demonstrated for a series of detection regions ranging from 365 nm to 250 nm. Photolithography masks were designed to allow the fabrication of photodiode arrays that would hybridize to commercially available CMOS based readout integrated circuits (ROICs), used routinely for infrared photodiode imaging. Photodiode arrays were fabricated and indium bumps were deposited onto the diode contacts and the ROICs to provide electrical connection. The hybrid detector arrays were placed in leadless chip carriers, wirebonded, and connected to commercially available drive and readout circuitry. Images of UV scenes were focused onto the arrays using fused quartz lenses. These images and movies

  14. Microscopy with microlens arrays: high throughput, high resolution and light-field imaging.

    Science.gov (United States)

    Orth, Antony; Crozier, Kenneth

    2012-06-04

    We demonstrate highly parallelized fluorescence scanning microscopy using a refractive microlens array. Fluorescent beads and rat femur tissue are imaged over a 5.5 mm x 5.5 mm field of view at a pixel throughput of up to 4 megapixels/s and a resolution of 706 nm. We also demonstrate the ability to extract different perspective views of a pile of microspheres.

  15. Low frequency ultrasonic array imaging using signal post-processing for concrete material

    Science.gov (United States)

    Ozawa, Akio; Izumi, Hideki; Nakahata, Kazuyuki; Ohira, Katsumi; Ogawa, Kenzo

    2017-02-01

    The use of ultrasonic arrays to conduct nondestructive evaluation has significantly increased in recent years. A post-processing beam-forming technique that utilizes a complete set of signals of all combinations of transmission and reception el-ements was proposed as an array imaging technique. In this study, a delay-and-sum beam reconstruction method utilizing post-processing was applied to the imaging of internal voids and reinforced steel bars in concrete material. Due to the high attenuation of the ultrasonic wave in concrete, it is necessary to use an ultrasonic wave as the incident wave at low frequencies and high in-tensities. In this study, an array transducer with a total of 16 elements was designed on the basis of a multigaussian beam model. The center frequency of the transducer was 50 kHz, and low frequency imaging was achieved by performing computations using a graphics processing unit accelerators in the post-processing beam formation. The results indicated that the shapes of through holes and steel bars in a concrete specimen with 700 mm height were reconstructed with high resolution.

  16. Assesment on the performance of electrode arrays using image processing technique

    Science.gov (United States)

    Usman, N.; Khiruddin, A.; Nawawi, Mohd

    2017-08-01

    Interpreting inverted resistivity section is time consuming, tedious and requires other sources of information to be relevant geologically. Image processing technique was used in order to perform post inversion processing which make geophysical data interpretation easier. The inverted data sets were imported into the PCI Geomatica 9.0.1 for further processing. The data sets were clipped and merged together in order to match the coordinates of the three layers and permit pixel to pixel analysis. Dipole-dipole array is more sensitive to resistivity variation with depth in comparison with Werner-Schlumberger and pole-dipole. Image processing serves as good post-inversion tool in geophysical data processing.

  17. Conformal Bulk Ablation And Therapy Monitoring Using Intracorporeal Image-Treat Ultrasound Arrays

    Science.gov (United States)

    Makin, I. R.; Faidi, W.; Mast, T. D.; Runk, M.; Slayton, M.; Barthe, P.

    2005-03-01

    For thermal treatment of soft tissue, an alternative to HIFU is bulk ablation using unfocused or weakly focused intense ultrasound fields. This approach offers faster ablation of large tissue volumes and can be performed in minimally invasive (e.g., laparoscopic or percutaneous) procedures. Here, methods for image-guided ablation of large tissue volumes using compact dual-modality (image and treat) ultrasound arrays are reported including tissue modification caused by the thermal therapy. The dual-modality arrays developed have 16-64 elements spanning apertures of 2-8 mm in elevation and 24-48 mm in azimuth. These devices can provide both therapeutically significant power (e.g. source intensity > 80 W/cm2 at 3.1 MHz) and broad bandwidth (e.g. 50% with a center frequency of 3.5 MHz) for imaging. Imaging challenges associated with limited probe dimensions and channel count are met using signal processing techniques that improve definition and contrast, allowing high-quality B-scan images and useful monitoring information to be obtained during therapy planning and treatment. Using linear and rotational scanning methods, large tissue volumes (20-60 cc) can be treated. The approach can be applied for ablation of other soft tissue pathologies, e.g., kidney, heart, uterus, brain, GI tract, etc.

  18. Wave path calculation for phased array imaging to evaluate weld zone of elbow pipes (Conference Presentation)

    Science.gov (United States)

    Park, Choon-Su; Park, Jin Kyu; Choi, Wonjae; Cho, Seunghyun; Kim, Dong-Yeol; Han, Ki Hyung

    2017-04-01

    It has long been non-destructively evaluated on weld joints of various pipes which are indispensable to most of industrial structures. Ultrasound evaluation has been used to detect flaws in welding joints, but some technical deficiencies still remain. Especially, ultrasound imaging on weld of elbow pipes has many challenging issues due to varying surface along circumferential direction. Conventional ultrasound imaging has particularly focused on ultrasonic wave propagation based on ray theory. This confines the incident angle and the position of an array transducer as well. Total focusing method (TFM), however, can provide not only high resolution images but also flexibility that enables to use ultrasonic waves to every direction that they can reach. This leads us to develop a method to get images of weld zone from an elbow part that curves. It is inevitable of each ultrasonic wave from the array transducer to transmit through different media and to be reflected from the boundary with angles along the curved surface. To form a correct PA image, careful calculation is made to ensure that time delay of receive-after-transmit is correctly shifted and summed even under non-planar boundary condition. Here, a method to calculate wave paths for the zone of interest at weld joint of an elbow pipe is presented. Numerical simulations of wave propagation on an elbow pipe are made to verify the proposed method. It is also experimentally demonstrated that the proposed method is well applied to various actual pipes that contains artificial flaws with a flexible wedge.

  19. Image fiber optic space-CDMA parallel transmission experiment using 8 x 8 VCSEL/PD arrays.

    Science.gov (United States)

    Nakamura, Moriya; Kitayama, Ken-ichi; Igasaki, Yasunori; Shamoto, Naoki; Kaneda, Keiji

    2002-11-10

    We experimentally demonstrate space-code-division multiple access (space-CDMA) based twodimensional (2-D) parallel optical interconnections by using image fibers and 8 x 8 vertical-cavity surface-emitting laser (VCSEL)/photo diode (PD) arrays. Two spatially encoded four-bit (2 x 2) parallel optical signals were emitted fiom 2-D VCSEL arrays and transmitted through image fibers. The encoded signals were multiplexed by an image-fiber coupler and detected by a 2-D PD array on the receiver side. The receiver recovered the intended parallel signal by decoding the signal. The transmission speed was 64 Mbps/ch (total throughput: 512 Mbps). Bit-error-rate (BER) measurement with a laterally misaligned PD array showed the array had a misalignment tolerance of 25 microm for a BER performance of 10(-9).

  20. Using a Planar Array of MEMS Microphones to Obtain Acoustic Images of a Fan Matrix

    Directory of Open Access Journals (Sweden)

    Lara del Val

    2017-01-01

    Full Text Available This paper proposes the use of a signal acquisition and processing system based on an 8×8 planar array of MEMS (Microelectromechanical Systems microphones to obtain acoustic images of a fan matrix. A 3×3 matrix of PC fans has been implemented to perform the study. Some tests to obtain the acoustic images of the individual fans and of the whole matrix have been defined and have been carried out inside an anechoic chamber. The nonstationary signals received by each MEMS microphone and their corresponding spectra have been analyzed, as well as the corresponding acoustic images. The analysis of the acoustic signals spectra reveals the resonance frequency of the individual fans. The obtained results reveal the feasibility of the proposed system to obtained acoustic images of a fan matrix and of its individual fans, in this last case, in order to estimate the real position of the fan inside the matrix.

  1. Study on magnetic mirror array image intensifier to work at room temperature.

    Science.gov (United States)

    Tang, Yuanhe; Yu, Yang; Gao, HaiYang; Liu, Shulin; Wang, Xiaolin

    2015-09-10

    In order to improve the detection capability of the current low-light-level (LLL) imaging systems at room temperature, a new device, a magnetic mirror array image intensifier (MMAII), is proposed in this paper. A magnetic mirror array device (MMAD) is coupled into an image intensifier which sits between the photocathode and the microchannel plate (MCP). The trace photoelectrons, one after another, are first sufficiently accumulated by the MMAD over a long time at room temperature, and then they are released and enter the MCP for further gain. These two steps are used to improve the detection capability at the LLL imaging system at room temperature. After the two-dimensional magnetic field distribution of the magnetic mirror array (MMA) is calculated, the MMA is designed and optimized with a rubidium Nd-Fe-B permanent magnet. Three groups of ideal parameters for the Nd-Fe-B permanent magnet MMAD, with a magnetic mirror ratio of 1.69, for all of them have been obtained. According to the research results on the noise of the escape cone of the MMAII, the angle between the incident direction and the axis is greater than 57°, so the trace electrons must be constrained by the magnetic mirror. We made 54 MMAs from Nd-Fe-B permanent magnets and packaged them in a container. Then the system was evacuated to 10-3  Pa at room temperature. It was found by experiment that the trace electrons could be actually constrained by the MMAD. The MMAII can be applied to images for static LLL objects.

  2. In vivo imaging of inducible tyrosinase gene expression with an ultrasound array-based photoacoustic system

    Science.gov (United States)

    Harrison, Tyler; Paproski, Robert J.; Zemp, Roger J.

    2012-02-01

    Tyrosinase, a key enzyme in the production of melanin, has shown promise as a reporter of genetic activity. While green fluorescent protein has been used extensively in this capacity, it is limited in its ability to provide information deep in tissue at a reasonable resolution. As melanin is a strong absorber of light, it is possible to image gene expression using tyrosinase with photoacoustic imaging technologies, resulting in excellent resolutions at multiple-centimeter depths. While our previous work has focused on creating and imaging MCF-7 cells with doxycycline-controlled tyrosinase expression, we have now established the viability of these cells in a murine model. Using an array-based photoacoustic imaging system with 5 MHz center frequency, we capture interleaved ultrasound and photoacoustic images of tyrosinase-expressing MCF-7 tumors both in a tissue mimicking phantom, and in vivo. Images of both the tyrosinase-expressing tumor and a control tumor are presented as both coregistered ultrasound-photoacoustic B-scan images and 3-dimensional photoacoustic volumes created by mechanically scanning the transducer. We find that the tyrosinase-expressing tumor is visible with a signal level 12dB greater than that of the control tumor in vivo. Phantom studies with excised tumors show that the tyrosinase-expressing tumor is visible at depths in excess of 2cm, and have suggested that our imaging system is sensitive to a transfection rate of less than 1%.

  3. Characteristics of Monolithically Integrated InGaAs Active Pixel Imager Array

    Science.gov (United States)

    Kim, Q.; Cunningham, T. J.; Pain, B.; Lange, M. J.; Olsen, G. H.

    2000-01-01

    Switching and amplifying characteristics of a newly developed monolithic InGaAs Active Pixel Imager Array are presented. The sensor array is fabricated from InGaAs material epitaxially deposited on an InP substrate. It consists of an InGaAs photodiode connected to InP depletion-mode junction field effect transistors (JFETs) for low leakage, low power, and fast control of circuit signal amplifying, buffering, selection, and reset. This monolithically integrated active pixel sensor configuration eliminates the need for hybridization with silicon multiplexer. In addition, the configuration allows the sensor to be front illuminated, making it sensitive to visible as well as near infrared signal radiation. Adapting the existing 1.55 micrometer fiber optical communication technology, this integration will be an ideal system of optoelectronic integration for dual band (Visible/IR) applications near room temperature, for use in atmospheric gas sensing in space, and for target identification on earth. In this paper, two different types of small 4 x 1 test arrays will be described. The effectiveness of switching and amplifying circuits will be discussed in terms of circuit effectiveness (leakage, operating frequency, and temperature) in preparation for the second phase demonstration of integrated, two-dimensional monolithic InGaAs active pixel sensor arrays for applications in transportable shipboard surveillance, night vision, and emission spectroscopy.

  4. Dual-Polarization, Multi-Frequency Antenna Array for use with Hurricane Imaging Radiometer

    Science.gov (United States)

    Little, John

    2013-01-01

    Advancements in common aperture antenna technology were employed to utilize its proprietary genetic algorithmbased modeling tools in an effort to develop, build, and test a dual-polarization array for Hurricane Imaging Radiometer (HIRAD) applications. Final program results demonstrate the ability to achieve a lightweight, thin, higher-gain aperture that covers the desired spectral band. NASA employs various passive microwave and millimeter-wave instruments, such as spectral radiometers, for a range of remote sensing applications, from measurements of the Earth's surface and atmosphere, to cosmic background emission. These instruments such as the HIRAD, SFMR (Stepped Frequency Microwave Radiometer), and LRR (Lightweight Rainfall Radiometer), provide unique data accumulation capabilities for observing sea surface wind, temperature, and rainfall, and significantly enhance the understanding and predictability of hurricane intensity. These microwave instruments require extremely efficient wideband or multiband antennas in order to conserve space on the airborne platform. In addition, the thickness and weight of the antenna arrays is of paramount importance in reducing platform drag, permitting greater time on station. Current sensors are often heavy, single- polarization, or limited in frequency coverage. The ideal wideband antenna will have reduced size, weight, and profile (a conformal construct) without sacrificing optimum performance. The technology applied to this new HIRAD array will allow NASA, NOAA, and other users to gather information related to hurricanes and other tropical storms more cost effectively without sacrificing sensor performance or the aircraft time on station. The results of the initial analysis and numerical design indicated strong potential for an antenna array that would satisfy all of the design requirements for a replacement HIRAD array. Multiple common aperture antenna methodologies were employed to achieve exceptional gain over the entire

  5. Fluorescence lifetime imaging using a single photon avalanche diode array sensor (Conference Presentation)

    Science.gov (United States)

    Wargocki, Piotr M.; Spence, David J.; Goldys, Ewa M.; Charbon, Edoardo; Bruschini, Claudio E.; Antalović, Ivan Michel; Burri, Samuel

    2017-02-01

    Single photon detectors allows us work with the weakest fluorescence signals. Single photon arrays, combined with ps-controlled gating allow us to create image maps of fluorescence lifetimes, which can be used for in-vivo discrimination of tissue activity. Here we present fluorescence lifetime imaging using the `SwissSPAD' sensor, a 512-by-128-pixel array of gated single photon detectors, fabricated in a standard high-voltage 0.35 μm CMOS process. We present a protocol for spatially resolved lifetime measurements where the lifetime can be retrieved for each pixel. We demonstrate the system by imaging patterns of Fluorescein and Rhodamine B on test slides, as well as measuring mixed samples to retrieve both components of the decay lifetime. The single photon sensitivity of the sensor creates a valuable instrument to perform live cell or live animal (in vivo) measurements of the weak autofluorescent signals, for example distinguishing unlabelled free and bound NADH. Our ultimate goal is to create a real time fluorescence lifetime imaging system, possibly integrated into augmented reality goggles, which could allow immediate discrimination of in vivo tissues.

  6. In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

    Science.gov (United States)

    Li, Mingyan; Jin, Jin; Zuo, Zhentao; Liu, Feng; Trakic, Adnan; Weber, Ewald; Zhuo, Yan; Xue, Rong; Crozier, Stuart

    2015-03-01

    Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) was capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo sensitivity profiles (B1-) become distinct at various angular positions. Therefore, sensitivity maps at other angular positions cannot be obtained by numerically rotating the acquired ones. In this work, a novel sensitivity estimation method for the RRFCA was developed and validated with human brain imaging. This method employed a library database and registration techniques to estimate coil sensitivity at an arbitrary angular position. The estimated sensitivity maps were then compared to the acquired sensitivity maps. The results indicate that the proposed method is capable of accurately estimating both magnitude and phase of sensitivity at an arbitrary angular position, which enables us to employ the rotating-SENSE algorithm to accelerate acquisition and reconstruct image. Compared to a stationary coil array with the same number of coil elements, the RRFCA was able to reconstruct images with better quality at a high reduction factor. It is hoped that the proposed rotation-dependent sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI.

  7. The wavenumber algorithm for full-matrix imaging using an ultrasonic array.

    Science.gov (United States)

    Hunter, Alan J; Drinkwater, Bruce W; Wilcox, Paul D

    2008-11-01

    Ultrasonic imaging using full-matrix capture, e.g., via the total focusing method (TFM), has been shown to increase angular inspection coverage and improve sensitivity to small defects in nondestructive evaluation. In this paper, we develop a Fourier-domain approach to full-matrix imaging based on the wavenumber algorithm used in synthetic aperture radar and sonar. The extension to the wavenumber algorithm for full-matrix data is described and the performance of the new algorithm compared with the TFM, which we use as a representative benchmark for the time-domain algorithms. The wavenumber algorithm provides a mathematically rigorous solution to the inverse problem for the assumed forward wave propagation model, whereas the TFM employs heuristic delay-and-sum beamforming. Consequently, the wavenumber algorithm has an improved point-spread function and provides better imagery. However, the major advantage of the wavenumber algorithm is its superior computational performance. For large arrays and images, the wavenumber algorithm is several orders of magnitude faster than the TFM. On the other hand, the key advantage of the TFM is its flexibility. The wavenumber algorithm requires a regularly sampled linear array, while the TFM can handle arbitrary imaging geometries. The TFM and the wavenumber algorithm are compared using simulated and experimental data.

  8. Evaluation of ultrasonic array imaging algorithms for inspection of a coarse grained material

    Science.gov (United States)

    Van Pamel, A.; Lowe, M. J. S.; Brett, C. R.

    2014-02-01

    Improving the ultrasound inspection capability for coarse grain metals remains of longstanding interest to industry and the NDE research community and is expected to become increasingly important for next generation power plants. A test sample of coarse grained Inconel 625 which is representative of future power plant components has been manufactured to test the detectability of different inspection techniques. Conventional ultrasonic A, B, and C-scans showed the sample to be extraordinarily difficult to inspect due to its scattering behaviour. However, in recent years, array probes and Full Matrix Capture (FMC) imaging algorithms, which extract the maximum amount of information possible, have unlocked exciting possibilities for improvements. This article proposes a robust methodology to evaluate the detection performance of imaging algorithms, applying this to three FMC imaging algorithms; Total Focusing Method (TFM), Phase Coherent Imaging (PCI), and Decomposition of the Time Reversal Operator with Multiple Scattering (DORT MSF). The methodology considers the statistics of detection, presenting the detection performance as Probability of Detection (POD) and probability of False Alarm (PFA). The data is captured in pulse-echo mode using 64 element array probes at centre frequencies of 1MHz and 5MHz. All three algorithms are shown to perform very similarly when comparing their flaw detection capabilities on this particular case.

  9. In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla.

    Science.gov (United States)

    Li, Mingyan; Jin, Jin; Zuo, Zhentao; Liu, Feng; Trakic, Adnan; Weber, Ewald; Zhuo, Yan; Xue, Rong; Crozier, Stuart

    2015-03-01

    Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) was capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo sensitivity profiles (B1(-)) become distinct at various angular positions. Therefore, sensitivity maps at other angular positions cannot be obtained by numerically rotating the acquired ones. In this work, a novel sensitivity estimation method for the RRFCA was developed and validated with human brain imaging. This method employed a library database and registration techniques to estimate coil sensitivity at an arbitrary angular position. The estimated sensitivity maps were then compared to the acquired sensitivity maps. The results indicate that the proposed method is capable of accurately estimating both magnitude and phase of sensitivity at an arbitrary angular position, which enables us to employ the rotating-SENSE algorithm to accelerate acquisition and reconstruct image. Compared to a stationary coil array with the same number of coil elements, the RRFCA was able to reconstruct images with better quality at a high reduction factor. It is hoped that the proposed rotation-dependent sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Information theory analysis of sensor-array imaging systems for computer vision

    Science.gov (United States)

    Huck, F. O.; Fales, C. L.; Park, S. K.; Samms, R. W.; Self, M. O.

    1983-01-01

    Information theory is used to assess the performance of sensor-array imaging systems, with emphasis on the performance obtained with image-plane signal processing. By electronically controlling the spatial response of the imaging system, as suggested by the mechanism of human vision, it is possible to trade-off edge enhancement for sensitivity, increase dynamic range, and reduce data transmission. Computational results show that: signal information density varies little with large variations in the statistical properties of random radiance fields; most information (generally about 85 to 95 percent) is contained in the signal intensity transitions rather than levels; and performance is optimized when the OTF of the imaging system is nearly limited to the sampling passband to minimize aliasing at the cost of blurring, and the SNR is very high to permit the retrieval of small spatial detail from the extensively blurred signal. Shading the lens aperture transmittance to increase depth of field and using a regular hexagonal sensor-array instead of square lattice to decrease sensitivity to edge orientation also improves the signal information density up to about 30 percent at high SNRs.

  11. Design of Frame-transferred Surface Array CCD Imaging System for Dark Objects

    Science.gov (United States)

    Zhang, Yu-heng; Yan, Yi-hua

    2016-01-01

    In order to realize the requirement of low-noise observations of dark objects in deep-space explorations, the design method for a simple and stable space camera imaging system is proposed in this paper. Based on the back-illuminated frame-transferred surface array CCD (CCD47-20AIMO) produced by the British E2V company, the circuitry design is given for the every part of the system. In which the applications of the correlated double-sampling analog-digital converter (AD) and the synchronous dynamic random access memory (SDRAM) can effectively suppress the correlated noise in the image signal. In addition, a drive control method favorable to the adjustment of exposure time is proposed, in the light-sensing stage it provides the exposure time with an independent and adjustable time delay to make the imaging system satisfy the requirement of long exposure time setting. The imaging system adopts the Cyclone III-series EP3C25Q240C8 field programable gate array produced by the Altera company as the kernel control device, and the drives are programmed in modules according to the function of the every device, in favor of transplantation. The simulative and experimental results indicate that the drive circuitry works normally, and that the system design can satisfy the preset requirement.

  12. Photoacoustic imaging of brachytherapy seeds using a channel-domain ultrasound array system

    Science.gov (United States)

    Harrison, Tyler; Zemp, Roger J.

    2011-03-01

    Brachytherapy is a technique commonly used in the treatment of prostate cancer that relies on the precise placement of small radioactive seeds near the tumor location. The advantage of this technique over traditional radiation therapies is that treatment can be continuous and uniform, resulting in fewer clinic visits and a shorter treatment duration. Two important phases of this treatment are needle guidance for implantation, and post-placement verification for dosimetry. Ultrasound is a common imaging modality used for these purposes, but it can be difficult to distinguish the seeds from surrounding tissues, often requiring other imaging techniques such as MRI or CT. Photoacoustic imaging may offer a viable alternative. Using a photoacoustic system based on an L7- 4 array transducer and a realtime ultrasound array system capable of parallel channel data acquisition streamed to a multi-core computer via PCI-express, we have demonstrated imaging of these seeds at an ultrasound depth of 16 mm and laser penetration depths ranging up to 50 mm in chicken tissue with multiple optical wavelengths. Ultrasound and photoacoustic images are coregistered via an interlaced pulse sequence. Two laser pulses are used to form a photoacoustic image, and at these depths, the brachytherapy seeds are detected with a signal-to-noise ratio of over 26dB. To obtain this result, 1064nm light was used with a fluence of 100mJ/cm2, the ANSI limit for human skin exposure at this wavelength. This study demonstrates the potential for photoacoustic imaging as a candidate technology for brachytherapy seed placement guidance and verification.

  13. Image Reconstruction in Radio Astronomy with Non-Coplanar Synthesis Arrays

    Science.gov (United States)

    Goodrick, L.

    2015-03-01

    Traditional radio astronomy imaging techniques assume that the interferometric array is coplanar, with a small field of view, and that the two-dimensional Fourier relationship between brightness and visibility remains valid, allowing the Fast Fourier Transform to be used. In practice, to acquire more accurate data, the non-coplanar baseline effects need to be incorporated, as small height variations in the array plane introduces the w spatial frequency component. This component adds an additional phase shift to the incoming signals. There are two approaches to account for the non-coplanar baseline effects: either the full three-dimensional brightness and visibility model can be used to reconstruct an image, or the non-coplanar effects can be removed, reducing the three dimensional relationship to that of the two-dimensional one. This thesis describes and implements the w-projection and w-stacking algorithms. The aim of these algorithms is to account for the phase error introduced by non-coplanar synthesis arrays configurations, making the recovered visibilities more true to the actual brightness distribution model. This is done by reducing the 3D visibilities to a 2D visibility model. The algorithms also have the added benefit of wide-field imaging, although w-stacking supports a wider field of view at the cost of more FFT bin support. For w-projection, the w-term is accounted for in the visibility domain by convolving it out of the problem with a convolution kernel, allowing the use of the two-dimensional Fast Fourier Transform. Similarly, the w-Stacking algorithm applies a phase correction in the image domain to image layers to produce an intensity model that accounts for the non-coplanar baseline effects. This project considers the KAT7 array for simulation and analysis of the limitations and advantages of both the algorithms. Additionally, a variant of the Högbom CLEAN algorithm was used which employs contour trimming for extended source emission flagging. The

  14. Airship Sparse Array Antenna Radar Real Aperture Imaging Based on Compressed Sensing and Sparsity in Transform Domain

    Directory of Open Access Journals (Sweden)

    Li Liechen

    2016-02-01

    Full Text Available A conformal sparse array based on combined Barker code is designed for airship platform. The performance of the designed array such as signal-to-noise ratio is analyzed. Using the hovering characteristics of the airship, interferometry operation can be applied on the real aperture imaging results of two pulses, which can eliminate the random backscatter phase and make the image sparse in the transform domain. Building the relationship between echo and transform coefficients, the Compressed Sensing (CS theory can be introduced to solve the formula and achieving imaging. The image quality of the proposed method can reach the image formed by the full array imaging. The simulation results show the effectiveness of the proposed method.

  15. New images of the crustal structure beneath eastern Tibet from a high-density seismic array

    Science.gov (United States)

    Liu, Zhen; Tian, Xiaobo; Gao, Rui; Wang, Gaochun; Wu, Zhenbo; Zhou, Beibei; Tan, Ping; Nie, Shitan; Yu, Guiping; Zhu, Gaohua; Xu, Xiao

    2017-12-01

    An east-west trending, high-density seismic array was deployed along the eastern margin of the Tibetan Plateau to investigate its eastward expansion. The 160 km long array spans the Ruoergai basin, Minjiang fault, Minshan Mountains, Tazang fault, and West Qinling. The array included 330 short-period seismographs spaced at 500 m intervals, which recorded teleseismic 3-component waveforms over a one month period. P-wave receiver functions calculated from 35 teleseismic events provided an image of crustal structure. The results show a massive thrust nappe structure around the Minshan Mountains and beneath the Minjiang fault. We suggest that this nappe formed after the closure of the Paleo-Tethyan ocean. The resultant Triassic thrusting contributed to partial uplift of the eastern Ruoergai basin and the Minshan Mountains in middle-to-late Miocene time. Receiver function images show that the Tazang fault is a crustal-scale rupture cutting across the Moho. The western Tazang fault appears as a nearly vertical strike-slip fault accommodating left lateral shear at the terminus of the eastern Kunlun fault. After clockwise rotation from an approximate east-west orientation to a nearly north-south orientation, the eastern Tazang fault became a west-dipping thrust fault, which caused crustal thickening beneath the Minshan Mountains and the West Qinling. Our results suggest that late Cenozoic uplift of the eastern margin of the plateau is produced by eastward overthrusting and crustal shortening, processes that absorbed slip along the Tazang and Kunlun faults.

  16. Combining Multiple Electrode Arrays for Two-Dimensional Electrical Resistivity Imaging Using the Unsupervised Classification Technique

    Science.gov (United States)

    Ishola, K. S.; Nawawi, M. N. M.; Abdullah, K.

    2015-06-01

    This article describes the use of k-means clustering, an unsupervised image classification technique, to help interpret subsurface targets. The k-means algorithm is employed to combine and classify the two-dimensional (2D) inverse resistivity models obtained from three different electrode arrays. The algorithm is initialized through the selection of the number of clusters, number of iterations and other parameters such as stopping criteria. Automatically, it seeks to find groups of closely related resistivity values that belong to the same cluster and are more similar to each other than resistivity values belonging to other clusters. The approach is applied to both synthetic and field data. The 2D postinversions of the resistivity data were preprocessed by resampling and interpolating to the same coordinate. Following the preprocessing, the three images are combined into a single classified image. All the image preprocessing, manipulation and analysis are performed using the PCI Geomatics software package. The results of the clustering and classification are presented as classified images. An assessment of the performance of the individual and combined images for the synthetic models is carried out using an error matrix, mean absolute error and mean absolute percent error. The estimated errors show that images obtained from maximum values of the reconstructed resistivity for the different models give the best representation of the true models. Additionally, the overall accuracy and kappa values show good agreement between the combined classified images and true models. Depending on the model, the overall accuracy ranges from 86 to 99 %, while the kappa coefficient is in the range of 54-98 %. Classified images with kappa coefficients greater than 0.8 show strong agreement, while images with kappa coefficients greater than 0.5 but less than 0.8 give moderate agreement. For the field data, the k-mean classifier produces images that incorporate structural features of

  17. CHAMP + : A powerful array receiver for APEX

    NARCIS (Netherlands)

    Kasemann, C.; Güsten, R.; Heyminck, S.; Klein, B.; Klein, T.; Philipp, S. D.; Korn, A.; Schneider, G.; Henseler, A.; Baryshev, A.; Klapwijk, T. M.

    2006-01-01

    CHAMP +, a dual-color 2 × 7 element heterodyne array for operation in the 450 μm and 350 μm atmospheric windows is under development. The instrument, which is currently undergoing final evaluation in the laboratories, will be deployed for commissioning at the APEX telescope in August this year. With

  18. CHAMP+ : A powerful array receiver for APEX

    NARCIS (Netherlands)

    Kasemann, C.; Güsten, R.; Heyminck, S.; Klein, B.; Klein, T.; Philipp, S.D.; Korn, A.; Schneider, G.; Henseler, A.; Baryshev, A.; Klapwijk, T.M.

    2006-01-01

    CHAMP+, a dual-color 2 × 7 element heterodyne array for operation in the 450 ?m and 350 ?m atmospheric windows is under development. The instrument, which is currently undergoing final evaluation in the laboratories, will be deployed for commissioning at the APEX telescope in August this year. With

  19. Full image-processing pipeline in field-programmable gate array for a small endoscopic camera

    Science.gov (United States)

    Mostafa, Sheikh Shanawaz; Sousa, L. Natércia; Ferreira, Nuno Fábio; Sousa, Ricardo M.; Santos, Joao; Wäny, Martin; Morgado-Dias, F.

    2017-01-01

    Endoscopy is an imaging procedure used for diagnosis as well as for some surgical purposes. The camera used for the endoscopy should be small and able to produce a good quality image or video, to reduce discomfort of the patients, and to increase the efficiency of the medical team. To achieve these fundamental goals, a small endoscopy camera with a footprint of 1 mm×1 mm×1.65 mm is used. Due to the physical properties of the sensors and human vision system limitations, different image-processing algorithms, such as noise reduction, demosaicking, and gamma correction, among others, are needed to faithfully reproduce the image or video. A full image-processing pipeline is implemented using a field-programmable gate array (FPGA) to accomplish a high frame rate of 60 fps with minimum processing delay. Along with this, a viewer has also been developed to display and control the image-processing pipeline. The control and data transfer are done by a USB 3.0 end point in the computer. The full developed system achieves real-time processing of the image and fits in a Xilinx Spartan-6LX150 FPGA.

  20. Image quality improvement in megavoltage cone beam CT using an imaging beam line and a sintered pixelated array system

    Energy Technology Data Exchange (ETDEWEB)

    Breitbach, Elizabeth K.; Maltz, Jonathan S.; Gangadharan, Bijumon; Bani-Hashemi, Ali; Anderson, Carryn M.; Bhatia, Sudershan K.; Stiles, Jared; Edwards, Drake S.; Flynn, Ryan T. [Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States); Siemens Oncology Care Systems, Siemens Medical Solutions, Inc., Concord, California 94520 (United States); Department of Radiation Oncology, University of Iowa, 200 Hawkins Drive, Iowa City, Iowa 52242 (United States)

    2011-11-15

    Purpose: To quantify the improvement in megavoltage cone beam computed tomography (MVCBCT) image quality enabled by the combination of a 4.2 MV imaging beam line (IBL) with a carbon electron target and a detector system equipped with a novel sintered pixelated array (SPA) of translucent Gd{sub 2}O{sub 2}S ceramic scintillator. Clinical MVCBCT images are traditionally acquired with the same 6 MV treatment beam line (TBL) that is used for cancer treatment, a standard amorphous Si (a-Si) flat panel imager, and the Kodak Lanex Fast-B (LFB) scintillator. The IBL produces a greater fluence of keV-range photons than the TBL, to which the detector response is more optimal, and the SPA is a more efficient scintillator than the LFB. Methods: A prototype IBL + SPA system was installed on a Siemens Oncor linear accelerator equipped with the MVision{sup TM} image guided radiation therapy (IGRT) system. A SPA strip consisting of four neighboring tiles and measuring 40 cm by 10.96 cm in the crossplane and inplane directions, respectively, was installed in the flat panel imager. Head- and pelvis-sized phantom images were acquired at doses ranging from 3 to 60 cGy with three MVCBCT configurations: TBL + LFB, IBL + LFB, and IBL + SPA. Phantom image quality at each dose was quantified using the contrast-to-noise ratio (CNR) and modulation transfer function (MTF) metrics. Head and neck, thoracic, and pelvic (prostate) cancer patients were imaged with the three imaging system configurations at multiple doses ranging from 3 to 15 cGy. The systems were assessed qualitatively from the patient image data. Results: For head and neck and pelvis-sized phantom images, imaging doses of 3 cGy or greater, and relative electron densities of 1.09 and 1.48, the CNR average improvement factors for imaging system change of TBL + LFB to IBL + LFB, IBL + LFB to IBL + SPA, and TBL + LFB to IBL + SPA were 1.63 (p < 10{sup -8}), 1.64 (p < 10{sup -13}), 2.66 (p < 10{sup -9}), respectively. For all imaging

  1. Image quality improvement in megavoltage cone beam CT using an imaging beam line and a sintered pixelated array system.

    Science.gov (United States)

    Breitbach, Elizabeth K; Maltz, Jonathan S; Gangadharan, Bijumon; Bani-Hashemi, Ali; Anderson, Carryn M; Bhatia, Sudershan K; Stiles, Jared; Edwards, Drake S; Flynn, Ryan T

    2011-11-01

    To quantify the improvement in megavoltage cone beam computed tomography (MVCBCT) image quality enabled by the combination of a 4.2 MV imaging beam line (IBL) with a carbon electron target and a detector system equipped with a novel sintered pixelated array (SPA) of translucent Gd(2)O(2)S ceramic scintillator. Clinical MVCBCT images are traditionally acquired with the same 6 MV treatment beam line (TBL) that is used for cancer treatment, a standard amorphous Si (a-Si) flat panel imager, and the Kodak Lanex Fast-B (LFB) scintillator. The IBL produces a greater fluence of keV-range photons than the TBL, to which the detector response is more optimal, and the SPA is a more efficient scintillator than the LFB. A prototype IBL + SPA system was installed on a Siemens Oncor linear accelerator equipped with the MVision(TM) image guided radiation therapy (IGRT) system. A SPA strip consisting of four neighboring tiles and measuring 40 cm by 10.96 cm in the crossplane and inplane directions, respectively, was installed in the flat panel imager. Head- and pelvis-sized phantom images were acquired at doses ranging from 3 to 60 cGy with three MVCBCT configurations: TBL + LFB, IBL + LFB, and IBL + SPA. Phantom image quality at each dose was quantified using the contrast-to-noise ratio (CNR) and modulation transfer function (MTF) metrics. Head and neck, thoracic, and pelvic (prostate) cancer patients were imaged with the three imaging system configurations at multiple doses ranging from 3 to 15 cGy. The systems were assessed qualitatively from the patient image data. For head and neck and pelvis-sized phantom images, imaging doses of 3 cGy or greater, and relative electron densities of 1.09 and 1.48, the CNR average improvement factors for imaging system change of TBL + LFB to IBL + LFB, IBL + LFB to IBL + SPA, and TBL + LFB to IBL + SPA were 1.63 (p < 10(- 8)), 1.64 (p < 10(- 13)), 2.66 (p < 10(- 9)), respectively. For all

  2. A 72 × 60 Angle-Sensitive SPAD Imaging Array for Lens-less FLIM

    Directory of Open Access Journals (Sweden)

    Changhyuk Lee

    2016-09-01

    Full Text Available We present a 72 × 60, angle-sensitive single photon avalanche diode (A-SPAD array for lens-less 3D fluorescence lifetime imaging. An A-SPAD pixel consists of (1 a SPAD to provide precise photon arrival time where a time-resolved operation is utilized to avoid stimulus-induced saturation, and (2 integrated diffraction gratings on top of the SPAD to extract incident angles of the incoming light. The combination enables mapping of fluorescent sources with different lifetimes in 3D space down to micrometer scale. Futhermore, the chip presented herein integrates pixel-level counters to reduce output data-rate and to enable a precise timing control. The array is implemented in standard 180 nm complementary metal-oxide-semiconductor (CMOS technology and characterized without any post-processing.

  3. Convex Array Vector Velocity Imaging Using Transverse Oscillation and Its Optimization

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Brandt, Andreas Hjelm; Bachmann Nielsen, Michael

    2015-01-01

    A method for obtaining vector flow images using the transverse oscillation (TO) approach on a convex array is presented. The paper presents optimization schemes for TO fields and evaluates their performance using simulations and measurements with an experimental scanner. A 3-MHz 192-element convex...... array probe (pitch 0.33 mm) is used in both simulations and measurements. A parabolic velocity profile is simulated at a beam-to-flow angle of 90°. The optimization routine changes the lateral oscillation period λx as a function of depth to yield the best possible estimates based on the energy ratio...... between positive and negative spatial frequencies in the ultrasound field. The energy ratio is reduced from −17.1 dB to −22.1 dB. Parabolic profiles are estimated on simulated data using 16 emissions. The optimization gives a reduction in standard deviation from 8.81% to 7.4% for 16 emissions...

  4. Water management in a planar air-breathing fuel cell array using operando neutron imaging

    Science.gov (United States)

    Coz, E.; Théry, J.; Boillat, P.; Faucheux, V.; Alincant, D.; Capron, P.; Gébel, G.

    2016-11-01

    Operando Neutron imaging is used for the investigation of a planar air-breathing array comprising multiple cells in series. The fuel cell demonstrates a stable power density level of 150 mW/cm2. Water distribution and quantification is carried out at different operating points. Drying at high current density is observed and correlated to self-heating and natural convection. Working in dead-end mode, water accumulation at lower current density is largely observed on the anode side. However, flooding mechanisms are found to begin with water condensation on the cathode side, leading to back-diffusion and anodic flooding. Specific in-plane and through-plane water distribution is observed and linked to the planar array design.

  5. Supplemental Blue LED Lighting Array to Improve the Signal Quality in Hyperspectral Imaging of Plants

    Directory of Open Access Journals (Sweden)

    Anne-Katrin Mahlein

    2015-06-01

    Full Text Available Hyperspectral imaging systems used in plant science or agriculture often have suboptimal signal-to-noise ratio in the blue region (400–500 nm of the electromagnetic spectrum. Typically there are two principal reasons for this effect, the low sensitivity of the imaging sensor and the low amount of light available from the illuminating source. In plant science, the blue region contains relevant information about the physiology and the health status of a plant. We report on the improvement in sensitivity of a hyperspectral imaging system in the blue region of the spectrum by using supplemental illumination provided by an array of high brightness light emitting diodes (LEDs with an emission peak at 470 nm.

  6. Development of an ordered array of optoelectrochemical individually readable sensors with submicrometer dimensions: application to remote electrochemiluminescence imaging.

    Science.gov (United States)

    Chovin, Arnaud; Garrigue, Patrick; Vinatier, Philippe; Sojic, Neso

    2004-01-15

    A novel array of optoelectrochemical submicrometer sensors for remote electrochemiluminescence (ECL) imaging is presented. This device was fabricated by chemical etching of a coherent optical fiber bundle to produce a nanotip array. The surface of the etched bundle was sputter-coated with a thin layer of indium tin oxide in order to create a transparent and electrically conductive surface that is insulated eventually by a new electrophoretic paint except for the apex of the tip. These fabrication steps produced an ordered array of optoelectrochemical sensors with submicrometer dimensions that retains the optical fiber bundle architecture. The electrochemical behavior of the sensor array was independently characterized by cyclic voltammetry and ECL experiments. The steady-state current indicates that the sensors are diffusively independent. This sensor array was further studied with a co-reactant ECL model system, such as Ru(bpy)(3)(2+)/TPrA. We clearly observed an ordered array of individual ECL micrometer spots, which corresponds to the sensor array structure. While the sensors of the array are not individually addressable electrochemically, we could establish that the sensors are optically independent and individually readable. Finally, we show that remote ECL imaging is performed quantitatively through the optoelectrochemical sensor array itself.

  7. Resolution-enhanced integral imaging using two micro-lens arrays with different focal lengths for capturing and display.

    Science.gov (United States)

    Wang, Zi; Wang, Anting; Wang, Shulu; Ma, Xiaohui; Ming, Hai

    2015-11-02

    We proposed a resolution enhanced integral imaging display method using two micro-lens arrays (MLA) with different focal lengths for capturing and display respectively. An elemental image array (EIA) is captured with MLA of focal length of f(1) and a processed EIA is displayed with MLA of focal length of f(2) which is larger than f(1). We enlarge the "effective area" in processed EIA to increase the information obtained by viewer, in other words, enhance the viewing resolution. The two micro-lens arrays for capturing and display are g and mg distant from display device respectively, and we can get m(2) times resolution enhancement.

  8. Smart-phone based computational microscopy using multi-frame contact imaging on a fiber-optic array.

    Science.gov (United States)

    Navruz, Isa; Coskun, Ahmet F; Wong, Justin; Mohammad, Saqib; Tseng, Derek; Nagi, Richie; Phillips, Stephen; Ozcan, Aydogan

    2013-10-21

    We demonstrate a cellphone based contact microscopy platform, termed Contact Scope, which can image highly dense or connected samples in transmission mode. Weighing approximately 76 grams, this portable and compact microscope is installed on the existing camera unit of a cellphone using an opto-mechanical add-on, where planar samples of interest are placed in contact with the top facet of a tapered fiber-optic array. This glass-based tapered fiber array has ~9 fold higher density of fiber optic cables on its top facet compared to the bottom one and is illuminated by an incoherent light source, e.g., a simple light-emitting-diode (LED). The transmitted light pattern through the object is then sampled by this array of fiber optic cables, delivering a transmission image of the sample onto the other side of the taper, with ~3× magnification in each direction. This magnified image of the object, located at the bottom facet of the fiber array, is then projected onto the CMOS image sensor of the cellphone using two lenses. While keeping the sample and the cellphone camera at a fixed position, the fiber-optic array is then manually rotated with discrete angular increments of e.g., 1-2 degrees. At each angular position of the fiber-optic array, contact images are captured using the cellphone camera, creating a sequence of transmission images for the same sample. These multi-frame images are digitally fused together based on a shift-and-add algorithm through a custom-developed Android application running on the smart-phone, providing the final microscopic image of the sample, visualized through the screen of the phone. This final computation step improves the resolution and also removes spatial artefacts that arise due to non-uniform sampling of the transmission intensity at the fiber optic array surface. We validated the performance of this cellphone based Contact Scope by imaging resolution test charts and blood smears.

  9. Broadband Infrared Heterodyne Spectrometer: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, C G; Cunningham, C T; Tringe, J W

    2010-12-16

    This report summarizes the most important results of our effort to develop a new class of infrared spectrometers based on a novel broadband heterodyne design. Our results indicate that this approach could lead to a near-room temperature operation with performance limited only by quantum noise carried by the incoming signal. Using a model quantum-well infrared photodetector (QWIP), we demonstrated key performance features of our approach. For example, we directly measured the beat frequency signal generated by superimposing local oscillator (LO) light of one frequency and signal light of another through a spectrograph, by injecting the LO light at a laterally displaced input location. In parallel with the development of this novel spectrometer, we modeled a new approach to reducing detector volume though plasmonic resonance effects. Since dark current scales directly with detector volume, this ''photon compression'' can directly lead to lower currents. Our calculations indicate that dark current can be reduced by up to two orders of magnitude in an optimized ''superlens'' structure. Taken together, our spectrometer and dark current reduction strategies provide a promising path toward room temperature operation of a mid-wave and possibly long-wave infrared spectrometer.

  10. Optical Demonstration of a Medical Imaging System with an EMCCD-Sensor Array for Use in a High Resolution Dynamic X-ray Imager

    OpenAIRE

    Qu, Bin; Huang, Ying; Wang, Weiyuan; Sharma, Prateek; Kuhls-Gilcrist, Andrew T.; Cartwright, Alexander N.; Titus, Albert H.; Bednarek, Daniel R.; Rudin, Stephen

    2010-01-01

    Use of an extensible array of Electron Multiplying CCDs (EMCCDs) in medical x-ray imager applications was demonstrated for the first time. The large variable electronic-gain (up to 2000) and small pixel size of EMCCDs provide effective suppression of readout noise compared to signal, as well as high resolution, enabling the development of an x-ray detector with far superior performance compared to conventional x-ray image intensifiers and flat panel detectors. We are developing arrays of EMCC...

  11. Color Restoration of RGBN Multispectral Filter Array Sensor Images Based on Spectral Decomposition

    Directory of Open Access Journals (Sweden)

    Chulhee Park

    2016-05-01

    Full Text Available A multispectral filter array (MSFA image sensor with red, green, blue and near-infrared (NIR filters is useful for various imaging applications with the advantages that it obtains color information and NIR information simultaneously. Because the MSFA image sensor needs to acquire invisible band information, it is necessary to remove the IR cut-offfilter (IRCF. However, without the IRCF, the color of the image is desaturated by the interference of the additional NIR component of each RGB color channel. To overcome color degradation, a signal processing approach is required to restore natural color by removing the unwanted NIR contribution to the RGB color channels while the additional NIR information remains in the N channel. Thus, in this paper, we propose a color restoration method for an imaging system based on the MSFA image sensor with RGBN filters. To remove the unnecessary NIR component in each RGB color channel, spectral estimation and spectral decomposition are performed based on the spectral characteristics of the MSFA sensor. The proposed color restoration method estimates the spectral intensity in NIR band and recovers hue and color saturation by decomposing the visible band component and the NIR band component in each RGB color channel. The experimental results show that the proposed method effectively restores natural color and minimizes angular errors.

  12. Color Restoration of RGBN Multispectral Filter Array Sensor Images Based on Spectral Decomposition.

    Science.gov (United States)

    Park, Chulhee; Kang, Moon Gi

    2016-05-18

    A multispectral filter array (MSFA) image sensor with red, green, blue and near-infrared (NIR) filters is useful for various imaging applications with the advantages that it obtains color information and NIR information simultaneously. Because the MSFA image sensor needs to acquire invisible band information, it is necessary to remove the IR cut-offfilter (IRCF). However, without the IRCF, the color of the image is desaturated by the interference of the additional NIR component of each RGB color channel. To overcome color degradation, a signal processing approach is required to restore natural color by removing the unwanted NIR contribution to the RGB color channels while the additional NIR information remains in the N channel. Thus, in this paper, we propose a color restoration method for an imaging system based on the MSFA image sensor with RGBN filters. To remove the unnecessary NIR component in each RGB color channel, spectral estimation and spectral decomposition are performed based on the spectral characteristics of the MSFA sensor. The proposed color restoration method estimates the spectral intensity in NIR band and recovers hue and color saturation by decomposing the visible band component and the NIR band component in each RGB color channel. The experimental results show that the proposed method effectively restores natural color and minimizes angular errors.

  13. An LTCC Based Compact SIW Antenna Array Feed Network for a Passive Imaging Radiometer

    KAUST Repository

    Abuzaid, Hattan

    2013-02-05

    Passive millimeter-wave (PMMW) imaging is a technique that allows the detection of inherent millimeter-wave radiation emitted by bodies. Since different bodies with varying properties emit unequal power intensities, a contrast can be established to detect their presence. The advantage of this imaging scheme over other techniques, such as optical and infrared imaging, is its ability to operate under all weather conditions. This is because the relatively long wavelengths of millimeter-waves, as compared to visible light, penetrate through clouds, fog, and sandstorms. The core of a PMMW camera is an antenna, which receives the electromagnetic radiation from a scene. Because PMMW systems require high gains to operate, large antenna arrays are typically employed. This mandatory increase of antenna elements is associated with a large feeding network. Therefore, PMMW cameras usually have a big profile. In this work, two enabling technologies, namely, Substrate integrated Waveguide (SIW) and Low Temperature Co-fired Ceramic (LTCC), are coupled with an innovative design to miniaturize the passive front-end. The two technologies synergize very well with the shielded characteristics of SIW and the high density multilayer integration of LTCC. The proposed design involves a novel multilayer power divider, which is incorporated in a folded feed network structure by moving between layers. The end result is an efficient feeding network, which footprint is least affected by an increase in array size. This is because the addition of more elements is accommodated by a vertical expansion rather than a lateral one. To characterize the feed network, an antenna array has been designed and integrated through efficient transitions.The complete structure has been simulated and fabricated. The results demonstrate an excellent performance, manifesting in a gain of 20 dBi and a bandwidth of more than 11.4% at 35 GHz. These values satisfy the general requirements of a PMMW system.

  14. High-resolution pulse-counting array detectors for imaging and spectroscopy at ultraviolet wavelengths

    Science.gov (United States)

    Timothy, J. Gethyn; Bybee, Richard L.

    1986-01-01

    The performance characteristics of multianode microchannel array (MAMA) detector systems which have formats as large as 256 x 1024 pixels and which have application to imaging and spectroscopy at UV wavelengths are evaluated. Sealed and open-structure MAMA detector tubes with opaque CsI photocathodes can determine the arrival time of the detected photon to an accuracy of 100 ns or better. Very large format MAMA detectors with CsI and Cs2Te photocathodes and active areas of 52 x 52 mm (2048 x 2048 pixels) will be used as the UV solar blind detectors for the NASA STIS.

  15. Origins Space Telescope: HEterodyne Receiver for OST (HERO)

    Science.gov (United States)

    Bergin, Edwin; Wiedner, Martina; Laurens, Andre; Gerin, Maryvonne; HERO team, Origins Space Telescope Science and Technology Definition Team

    2018-01-01

    The Origins Space Telescope (OST) is a mission concept for the Far-Infrared Surveyor, one of the four science and technology definition studies selected by NASA HQ for the 2020 Astronomy and Astrophysics Decadal survey. The OST study will encompass two mission concepts (poster by A. Cooray). Concept 1 is an extremely versatile observatory with 5 science instruments, of which the HEterodyne Receivers for OST (HERO) is one.HERO’s main targets are high spectral resolution observations (Dl/l up to 107 or Dv = 0.03km/s) of water to follow its trail from cores to YSOs as well as H2O and HDO observations on comets to explore the origins of water. HERO will probe all neutral ISM phases using cooling lines ([CII], [OI]) and hydrides as probes of CO-dark H2 (CH, HF). HERO will reveal how molecular clouds and filaments form in the local ISM up to nearby galaxies. HERO will enable detailed understanding of feedback mechanisms : shocks, cosmic rays, UV induced feedback and will provide a map of the cosmic ray ionization rate in the Galaxy and nearby galaxies using molecular ions (ArH+, OH+, H3O+).In order to achieve these observational goals, HERO will cover an extremely wide frequency range from 468 to 2700 GHz (641 to 111microns) and a window around the OI line at 4563 to 4752GHz (66 to 63 microns). It will consist of very large focal plane arrays of 128 pixels between 900 - 2700 GHz and at 4.7 THz, and 32 pixels for the 468 to 900 GHz range. The instrument is exploiting Herschel/HIFI heritage, but will go well beyond HIFIs capacities. HERO’s large arrays require low dissipation and low power components. The HERO concept makes use of the latest cryogenic SiGe amplifier technology, as well as CMOS technology for the backends with 2 orders of magnitude lower power. Advances in Local Oscillator technology have also been taken into account and ambitious, but realistic assumptions have been made for future amplifier multiplier chains going up to 4.7 THz.Origins will enable

  16. OpenMSI Arrayed Analysis Toolkit: Analyzing Spatially Defined Samples Using Mass Spectrometry Imaging

    Energy Technology Data Exchange (ETDEWEB)

    de Raad, Markus [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); de Rond, Tristan [Univ. of California, Berkeley, CA (United States); Rübel, Oliver [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Keasling, Jay D. [Univ. of California, Berkeley, CA (United States); Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Technical Univ. of Denmark, Lyngby (Denmark); Northen, Trent R. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States); Bowen, Benjamin P. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); USDOE Joint Genome Institute (JGI), Walnut Creek, CA (United States)

    2017-05-03

    Mass spectrometry imaging (MSI) has primarily been applied in localizing biomolecules within biological matrices. Although well-suited, the application of MSI for comparing thousands of spatially defined spotted samples has been limited. One reason for this is a lack of suitable and accessible data processing tools for the analysis of large arrayed MSI sample sets. In this paper, the OpenMSI Arrayed Analysis Toolkit (OMAAT) is a software package that addresses the challenges of analyzing spatially defined samples in MSI data sets. OMAAT is written in Python and is integrated with OpenMSI (http://openmsi.nersc.gov), a platform for storing, sharing, and analyzing MSI data. By using a web-based python notebook (Jupyter), OMAAT is accessible to anyone without programming experience yet allows experienced users to leverage all features. OMAAT was evaluated by analyzing an MSI data set of a high-throughput glycoside hydrolase activity screen comprising 384 samples arrayed onto a NIMS surface at a 450 μm spacing, decreasing analysis time >100-fold while maintaining robust spot-finding. The utility of OMAAT was demonstrated for screening metabolic activities of different sized soil particles, including hydrolysis of sugars, revealing a pattern of size dependent activities. Finally, these results introduce OMAAT as an effective toolkit for analyzing spatially defined samples in MSI. OMAAT runs on all major operating systems, and the source code can be obtained from the following GitHub repository: https://github.com/biorack/omaat.

  17. Prototype AEGIS: A Pixel-Array Readout Circuit for Gamma-Ray Imaging

    Science.gov (United States)

    Barber, H. Bradford; Augustine, F. L.; Furenlid, L.; Ingram, C. M.; Grim, G. P.

    2015-01-01

    Semiconductor detector arrays made of CdTe/CdZnTe are expected to be the main components of future high-performance, clinical nuclear medicine imaging systems. Such systems will require small pixel-pitch and much larger numbers of pixels than are available in current semiconductor-detector cameras. We describe the motivation for developing a new readout integrated circuit, AEGIS, for use in hybrid semiconductor detector arrays, that may help spur the development of future cameras. A basic design for AEGIS is presented together with results of an HSPICE™ simulation of the performance of its unit cell. AEGIS will have a shaper-amplifier unit cell and neighbor pixel readout. Other features include the use of a single input power line with other biases generated on-board, a control register that allows digital control of all thresholds and chip configurations and an output approach that is compatible with list-mode data acquisition. An 8×8 prototype version of AEGIS is currently under development; the full AEGIS will be a 64×64 array with 300 μm pitch. PMID:26345126

  18. Tactile soft-sparse mean fluid-flow imaging with a robotic whisker array.

    Science.gov (United States)

    Tuna, Cagdas; Jones, Douglas L; Kamalabadi, Farzad

    2015-08-04

    An array of whiskers is critical to many mammals to survive in their environment. However, current engineered systems generally employ vision, radar or sonar to explore the surroundings, not having sufficiently benefited from tactile perception. Inspired by the whisking animals, we present here a novel tomography-based tactile fluid-flow imaging technique for the reconstruction of surroundings with an artificial whisker array. The moment sensed at the whisker base is the weighted integral of the drag force per length, which is proportional to the relative velocity squared on a whisker segment. We demonstrate that the 2D cross-sectional mean fluid-flow velocity-field can be successfully mapped out by collecting moment measurements at different angular positions with the whisker array. We use a regularized version of the FOCal underdetermined system solver algorithm with a smoothness constraint to obtain soft-sparse static estimates of the 2D cross-sectional velocity-squared distribution. This new proposed approach has the strong potential to be an alternative environmental sensing technology, particularly in dark or murky environments.

  19. Velocity measurement by coherent x-ray heterodyning

    Energy Technology Data Exchange (ETDEWEB)

    Lhermitte, Julien R. M.; Rogers, Michael C.; Manet, Sabine; Sutton, Mark

    2017-01-01

    We present a small-angle coherent x-ray scattering technique used for measuring flow velocities in slow moving materials. The technique is an extension of X-ray Photon Correlation Spectroscopy (XPCS): It involves mixing the scattering from moving tracer particles with a static reference that heterodynes the signal. This acts to elongate temporal effects caused by flow in homodyne measurements, allowing for a more robust measurement of flow properties. Using coherent x-ray heterodyning, velocities ranging from 0.1 to 10 μm/s were measured for a viscous fluid pushed through a rectangular channel. We describe experimental protocols and theory for making these Poiseuille flow profile measurements and also develop the relevant theory for using heterodyne XPCS to measure velocities in uniform and Couette flows.

  20. Multi-Axis Heterodyne Interferometry (MAHI)

    Science.gov (United States)

    Thorpe, James

    The detection and measurement of gravitational waves represents humanity’s next, and final, opportunity to open an entirely new spectrum with which to view the universe. The first steps of this process will likely take place later this decade when the second-generation ground-based instruments such as Advanced LIGO approach design sensitivity. While these events will be historic, it will take a space-based detector to access the milliHertz gravitational wave frequency band, a band that is rich in both number and variety of sources. The Laser Interferometer Space Antenna (LISA) concept has been developed over the past two decades in the US and Europe to provide access to this band. The European Space Agency recently selected The Gravitational Universe as the science theme for the 3rd Large-class mission in the Cosmic Visions Programme, with the assumption that a LISA-like instrument would be implemented for launch in 2034. NASA has expressed interest in partnering on this effort and the US community has made its own judgment on the scientific potential of a space-based gravitational wave observatory through the selection of LISA as the 3rd flagship mission in the 2010 Decadal Survey. Much of the effort has been in retiring risk for the unique technologies that comprise a gravitational wave detector. A prime focus of this effort is LISA Pathfinder (LPF), a dedicated technology demonstrator mission led by ESA with contributions from NASA and several member states. LPF’s primary objective is to validate drag-free flight as an approach to realizing an inertial reference mass. Along the way, several important technologies will be demonstrated, including picometer-level heterodyne interferometry. However, there are several important differences between the interferometry design for LISA and that for LPF. These mostly result from the fact that LISA interferometry involves multiple lasers on separate spacecraft whereas LPF can use a single laser on a single spacecraft

  1. Multi-Contrast Imaging and Digital Refocusing on a Mobile Microscope with a Domed LED Array.

    Directory of Open Access Journals (Sweden)

    Zachary F Phillips

    Full Text Available We demonstrate the design and application of an add-on device for improving the diagnostic and research capabilities of CellScope--a low-cost, smartphone-based point-of-care microscope. We replace the single LED illumination of the original CellScope with a programmable domed LED array. By leveraging recent advances in computational illumination, this new device enables simultaneous multi-contrast imaging with brightfield, darkfield, and phase imaging modes. Further, we scan through illumination angles to capture lightfield datasets, which can be used to recover 3D intensity and phase images without any hardware changes. This digital refocusing procedure can be used for either 3D imaging or software-only focus correction, reducing the need for precise mechanical focusing during field experiments. All acquisition and processing is performed on the mobile phone and controlled through a smartphone application, making the computational microscope compact and portable. Using multiple samples and different objective magnifications, we demonstrate that the performance of our device is comparable to that of a commercial microscope. This unique device platform extends the field imaging capabilities of CellScope, opening up new clinical and research possibilities.

  2. Multi-Contrast Imaging and Digital Refocusing on a Mobile Microscope with a Domed LED Array.

    Science.gov (United States)

    Phillips, Zachary F; D'Ambrosio, Michael V; Tian, Lei; Rulison, Jared J; Patel, Hurshal S; Sadras, Nitin; Gande, Aditya V; Switz, Neil A; Fletcher, Daniel A; Waller, Laura

    2015-01-01

    We demonstrate the design and application of an add-on device for improving the diagnostic and research capabilities of CellScope--a low-cost, smartphone-based point-of-care microscope. We replace the single LED illumination of the original CellScope with a programmable domed LED array. By leveraging recent advances in computational illumination, this new device enables simultaneous multi-contrast imaging with brightfield, darkfield, and phase imaging modes. Further, we scan through illumination angles to capture lightfield datasets, which can be used to recover 3D intensity and phase images without any hardware changes. This digital refocusing procedure can be used for either 3D imaging or software-only focus correction, reducing the need for precise mechanical focusing during field experiments. All acquisition and processing is performed on the mobile phone and controlled through a smartphone application, making the computational microscope compact and portable. Using multiple samples and different objective magnifications, we demonstrate that the performance of our device is comparable to that of a commercial microscope. This unique device platform extends the field imaging capabilities of CellScope, opening up new clinical and research possibilities.

  3. Megahertz rate, volumetric imaging of bubble clouds in sonothrombolysis using a sparse hemispherical receiver array

    Science.gov (United States)

    Acconcia, Christopher N.; Jones, Ryan M.; Goertz, David E.; O'Reilly, Meaghan A.; Hynynen, Kullervo

    2017-09-01

    It is well established that high intensity focused ultrasound can be used to disintegrate clots. This approach has the potential to rapidly and noninvasively resolve clot causing occlusions in cardiovascular diseases such as deep vein thrombosis (DVT). However, lack of an appropriate treatment monitoring tool is currently a limiting factor in its widespread adoption. Here we conduct cavitation imaging with a large aperture, sparse hemispherical receiver array during sonothrombolysis with multi-cycle burst exposures (0.1 or 1 ms burst lengths) at 1.51 MHz. It was found that bubble cloud generation on imaging correlated with the locations of clot degradation, as identified with high frequency (30 MHz) ultrasound following exposures. 3D images could be formed at integration times as short as 1 µs, revealing the initiation and rapid development of cavitation clouds. Equating to megahertz frame rates, this is an order of magnitude faster than any other imaging technique available for in vivo application. Collectively, these results suggest that the development of a device to perform DVT therapy procedures would benefit greatly from the integration of receivers tailored to bubble activity imaging.

  4. Tunable Talbot imaging distance using an array of beam-steered metamaterial leaky-wave antennas

    Science.gov (United States)

    Gómez-Díaz, J. S.; Álvarez-Melcón, A.; Gupta, S.; Caloz, C.

    2009-10-01

    A tunable spatio-temporal Talbot imaging phenomenon is presented. This phenomenon is based on the radiation properties of an array of beam-steered metamaterial composite right-/left-handed leaky-wave antennas, which is excited by a modulated pulse. The scanning law property of these antennas is exploited to achieve off-axis radiation, which leads to a tunable Talbot distance, as a function of the input pulse modulation frequency. The proposed Talbot phenomenon is analyzed theoretically, taking into account the aberrations produced by higher-order terms present in the free-space transfer function. Numerical simulations confirm the self-imaging and pulse multiplication effects and their tunability capabilities as a function of frequency. Finally, the experimental results are included to confirm the phenomenon predicted.

  5. Analysis of cortical arrays from Tradescantia virginiana at high resolution reveals discrete microtubule subpopulations and demonstrates that confocal images of arrays can be misleading.

    Science.gov (United States)

    Barton, Deborah A; Vantard, Marylin; Overall, Robyn L

    2008-04-01

    Cortical microtubule arrays are highly organized networks involved in directing cellulose microfibril deposition within the cell wall. Their organization results from complex interactions between individual microtubules and microtubule-associated proteins. The precise details of these interactions are often not evident using optical microscopy. Using high-resolution scanning electron microscopy, we analyzed extensive regions of cortical arrays and identified two spatially discrete microtubule subpopulations that exhibited different stabilities. Microtubules that lay adjacent to the plasma membrane were often bundled and more stable than the randomly aligned, discordant microtubules that lay deeper in the cytoplasm. Immunolabeling revealed katanin at microtubule ends, on curves, or at sites along microtubules in line with neighboring microtubule ends. End binding 1 protein also localized along microtubules, at microtubule ends or junctions between microtubules, and on the plasma membrane in direct line with microtubule ends. We show fine bands in vivo that traverse and may encircle microtubules. Comparing confocal and electron microscope images of fluorescently tagged arrays, we demonstrate that optical images are misleading, highlighting the fundamental importance of studying cortical microtubule arrays at high resolution.

  6. Uncooled Terahertz real-time imaging 2D arrays developed at LETI: present status and perspectives

    Science.gov (United States)

    Simoens, François; Meilhan, Jérôme; Dussopt, Laurent; Nicolas, Jean-Alain; Monnier, Nicolas; Sicard, Gilles; Siligaris, Alexandre; Hiberty, Bruno

    2017-05-01

    As for other imaging sensor markets, whatever is the technology, the commercial spread of terahertz (THz) cameras has to fulfil simultaneously the criteria of high sensitivity and low cost and SWAP (size, weight and power). Monolithic silicon-based 2D sensors integrated in uncooled THz real-time cameras are good candidates to meet these requirements. Over the past decade, LETI has been studying and developing such arrays with two complimentary technological approaches, i.e. antenna-coupled silicon bolometers and CMOS Field Effect Transistors (FET), both being compatible to standard silicon microelectronics processes. LETI has leveraged its know-how in thermal infrared bolometer sensors in developing a proprietary architecture for THz sensing. High technological maturity has been achieved as illustrated by the demonstration of fast scanning of large field of view and the recent birth of a commercial camera. In the FET-based THz field, recent works have been focused on innovative CMOS read-out-integrated circuit designs. The studied architectures take advantage of the large pixel pitch to enhance the flexibility and the sensitivity: an embedded in-pixel configurable signal processing chain dramatically reduces the noise. Video sequences at 100 frames per second using our 31x31 pixels 2D Focal Plane Arrays (FPA) have been achieved. The authors describe the present status of these developments and perspectives of performance evolutions are discussed. Several experimental imaging tests are also presented in order to illustrate the capabilities of these arrays to address industrial applications such as non-destructive testing (NDT), security or quality control of food.

  7. Convex array vector velocity imaging using transverse oscillation and its optimization.

    Science.gov (United States)

    Jensen, Jørgen Arendt; Brandt, Andreas Hjelm; Nielsen, Michael Bachmann

    2015-12-01

    A method for obtaining vector flow images using the transverse oscillation (TO) approach on a convex array is presented. The paper presents optimization schemes for TO fields and evaluates their performance using simulations and measurements with an experimental scanner. A 3-MHz 192-element convex array probe (pitch 0.33 mm) is used in both simulations and measurements. A parabolic velocity profile is simulated at a beam-to-flow angle of 90°. The optimization routine changes the lateral oscillation period λ࠭ as a function of depth to yield the best possible estimates based on the energy ratio between positive and negative spatial frequencies in the ultrasound field. The energy ratio is reduced from -17.1 dB to -22.1 dB. Parabolic profiles are estimated on simulated data using 16 emissions. The optimization gives a reduction in standard deviation from 8.81% to 7.4% for 16 emissions, with a reduction in lateral velocity bias from -15.93% to 0.78% at 90° (transverse flow) at a depth of 40 mm. Measurements have been performed using the experimental ultrasound scanner and a convex array transducer. A bias of -0.93% was obtained at 87° for a parabolic velocity profile along with a standard deviation of 6.37%. The livers of two healthy volunteers were scanned using the experimental setup. The in vivo images demonstrate that the method yields realistic estimates with a consistent angle and mean velocity across three heart cycles.

  8. Graphene-based liquid-crystal microlens arrays for synthetic-aperture imaging

    Science.gov (United States)

    Wu, Yong; Hu, Wei; Tong, Qing; Lei, Yu; Xin, Zhaowei; Wei, Dong; Zhang, Xinyu; Liao, Jing; Wang, Haiwei; Xie, Changsheng

    2017-09-01

    In this paper, a new kind of liquid-crystal microlens array with graphene electrodes controlled electrically are designed and fabricated successfully. The graphene-based liquid-crystal microlens arrays (GLCMAs) exhibit excellent beam focusing performances in both the visible and near infrared (NIR) wavelength regions and also synthetic aperture imaging function. The graphene films used to fabricate the electrodes of the GLCMAs are grown by chemical vapor deposition over copper foils, demonstrating several characters of low sheet resistance and high transmittance in both wavelength ranges above. The key processes for shaping the GLCMAs include: transferring graphene films from copper foils to wafers selected, conventional UV-photolithography, ICP etching, and liquid-crystal encapsulation. Through performing common optical measurements, the point spread functions of incident lasers with different wavelength, such as red lasers of ∼600 nm, green lasers of ∼532 nm, and NIR lasers of ∼980 nm, have been obtained. Several key parameters including focal spots size, average normalized light intensity, focal length, average deviation rate and contrast ratio have been acquired and analyzed. A particular synthetic-aperture imaging based on the GLCMA is realized so as to certify a fact that a single target pattern can be constructed effectively based on some sub-aperture patterns with several tens or hundreds of micrometer scale, and thus highlight a way to fast process partial or small-zoned patterns for enhancing the detection efficiency of special targets.

  9. MR imaging of the prostate at 3 Tesla: comparison of an external phased-array coil to imaging with an endorectal coil at 1.5 Tesla.

    Science.gov (United States)

    Sosna, Jacob; Pedrosa, Ivan; Dewolf, William C; Mahallati, Houman; Lenkinski, Robert E; Rofsky, Neil M

    2004-08-01

    To qualitatively compare the image quality of torso phased-array 3-Tesla (3T) imaging of the prostate with that of endorectal 1.5-Tesla imaging. Twenty cases of torso phased-array prostate imaging performed at 3-Tesla with FSE T2 weighted images were evaluated by two readers independently for visualization of the posterior border (PB), seminal vesicles (SV), neurovascular bundles (NVB), and image quality rating (IQR). Studies were performed at large fields of view(FOV) (25 cm) (14 cases) (3TL) and smaller FOV (14 cm) (19 cases) (3TS). A comparison was made to 20 consecutive cases of 1.5-T endorectal evaluation performed during the same time period.Results. 3TL produced a significantly better image quality compared with the small FOV for PB (P = .0001), SV (P =.0001), and IQR (P = .0001). There was a marginally significant difference within the NVB category (P = .0535). 3TL produced an image of similar quality to image quality at 1.5 T for PB (P = .3893), SV (P = .8680), NB (P = .2684), and IQR (P = .8599). Prostate image quality at 3T with a torso phased-array coil can be comparable with that of endorectal 1.5-T imaging. These findings suggest that additional options are now available for magnetic resonance imaging of the prostate gland.

  10. Forward-looking intracardiac ultrasound imaging using a 1-D CMUT array integrated with custom front-end electronics.

    Science.gov (United States)

    Nikoozadeh, Amin; Wygant, Ira O; Lin, Der-Song; Oralkan, Omer; Ergun, A Sanli; Stephens, Douglas N; Thomenius, Kai E; Dentinger, Aaron M; Wildes, Douglas; Akopyan, Gina; Shivkumar, Kalyanam; Mahajan, Aman; Sahn, David J; Khuri-Yakub, Butrus T

    2008-12-01

    Minimally invasive catheter-based electrophysiological (EP) interventions are becoming a standard procedure in diagnosis and treatment of cardiac arrhythmias. As a result of technological advances that enable small feature sizes and a high level of integration, nonfluoroscopic intracardiac echocardiography (ICE) imaging catheters are attracting increasing attention. ICE catheters improve EP procedural guidance while reducing the undesirable use of fluoroscopy, which is currently the common catheter guidance method. Phased-array ICE catheters have been in use for several years now, although only for side-looking imaging. We are developing a forward-looking ICE catheter for improved visualization. In this effort, we fabricate a 24-element, fine-pitch 1-D array of capacitive micromachined ultrasonic transducers (CMUT), with a total footprint of 1.73 mm x 1.27 mm. We also design a custom integrated circuit (IC) composed of 24 identical blocks of transmit/ receive circuitry, measuring 2.1 mm x 2.1 mm. The transmit circuitry is capable of delivering 25-V unipolar pulses, and the receive circuitry includes a transimpedance preamplifier followed by an output buffer. The CMUT array and the custom IC are designed to be mounted at the tip of a 10-Fr catheter for high-frame-rate forward-looking intracardiac imaging. Through-wafer vias incorporated in the CMUT array provide access to individual array elements from the back side of the array. We successfully flip-chip bond a CMUT array to the custom IC with 100% yield. We coat the device with a layer of polydimethylsiloxane (PDMS) to electrically isolate the device for imaging in water and tissue. The pulse-echo in water from a total plane reflector has a center frequency of 9.2 MHz with a 96% fractional bandwidth. Finally, we demonstrate the imaging capability of the integrated device on commercial phantoms and on a beating ex vivo rabbit heart (Langendorff model) using a commercial ultrasound imaging system.

  11. Forward-Looking Intracardiac Ultrasound Imaging Using a 1-D CMUT Array Integrated With Custom Front-End Electronics

    Science.gov (United States)

    Nikoozadeh, Amin; Wygant, Ira O.; Lin, Der-Song; Oralkan, Ömer; Ergun, A. Sanlı; Stephens, Douglas N.; Thomenius, Kai E.; Dentinger, Aaron M.; Wildes, Douglas; Akopyan, Gina; Shivkumar, Kalyanam; Mahajan, Aman; Sahn, David J.; Khuri-Yakub, Butrus T.

    2009-01-01

    Minimally invasive catheter-based electrophysiological (EP) interventions are becoming a standard procedure in diagnosis and treatment of cardiac arrhythmias. As a result of technological advances that enable small feature sizes and a high level of integration, nonfluoroscopic intracardiac echocardiography (ICE) imaging catheters are attracting increasing attention. ICE catheters improve EP procedural guidance while reducing the undesirable use of fluoroscopy, which is currently the common catheter guidance method. Phased-array ICE catheters have been in use for several years now, although only for side-looking imaging. We are developing a forward-looking ICE catheter for improved visualization. In this effort, we fabricate a 24-element, fine-pitch 1-D array of capacitive micromachined ultrasonic transducers (CMUT), with a total footprint of 1.73 mm × 1.27 mm. We also design a custom integrated circuit (IC) composed of 24 identical blocks of transmit/receive circuitry, measuring 2.1 mm × 2.1 mm. The transmit circuitry is capable of delivering 25-V unipolar pulses, and the receive circuitry includes a transimpedance preamplifier followed by an output buffer. The CMUT array and the custom IC are designed to be mounted at the tip of a 10-Fr catheter for high-frame-rate forward-looking intracardiac imaging. Through-wafer vias incorporated in the CMUT array provide access to individual array elements from the back side of the array. We successfully flip-chip bond a CMUT array to the custom IC with 100% yield. We coat the device with a layer of polydimethylsiloxane (PDMS) to electrically isolate the device for imaging in water and tissue. The pulse-echo in water from a total plane reflector has a center frequency of 9.2 MHz with a 96% fractional bandwidth. Finally, we demonstrate the imaging capability of the integrated device on commercial phantoms and on a beating ex vivo rabbit heart (Langendorff model) using a commercial ultrasound imaging system. PMID:19126489

  12. Linear-array-based photoacoustic imaging of human microcirculation with a range of high frequency transducer probes.

    Science.gov (United States)

    Zafar, Haroon; Breathnach, Aedán; Subhash, Hrebesh M; Leahy, Martin J

    2015-05-01

    Photoacoustic imaging (PAI) with a linear-array-based probe can provide a convenient means of imaging the human microcirculation within its native structural context and adds functional information. PAI using a multielement linear transducer array combined with multichannel collecting system was used for in vivo volumetric imaging of the blood microcirculation, the total concentration of hemoglobin (HbT), and the hemoglobin oxygen saturation (sO₂) within human tissue. Three-dimensional (3-D) PA and ultrasound (US) volumetric scans were acquired from the forearm skin by linearly translating the transducer with a stepper motor over a region of interest, while capturing two-dimensional images using 15, 21, and 40 MHz frequency transducer probes. For the microvasculature imaging, PA images were acquired at 800- and 1064-nm wavelengths. For the HbT and sO₂ estimates, PA images were collected at 750- and 850-nm wavelengths. 3-D microcirculation, HbT, and sO₂ maps of the forearm skin were obtained from normal subjects. The linear-array-based PAI has been found promising in terms of resolution, imaging depth, and imaging speed for in vivo microcirculation imaging within human skin. We believe that a reflection type probe, similar to existing clinical US probes, is most likely to succeed in real clinical applications. Its advantages include ease of use, speed, and familiarity for radiographers and clinicians.

  13. Diagnostic and quality-assurance tools for low-contrast images obtained from array detectors

    Science.gov (United States)

    Hatfield, D. B.; Sandel, Bill R.

    1993-01-01

    We investigate methods of estimating a background image frame for subtraction from a data frame for use when a more suitable measured background frame is not available. We define background as any signal component that is not attributable to the phenomenon currently under investigation. We describe a technique that is based on pixel-by-pixel least-squares regression of images for computing a background frame from available data. We argue that the same technique can be a useful quality-assurance tool for evaluating instrument performance. For example, it can help to separate image structure resulting from the reading process from structure resulting from the characteristics of the detector itself. We demonstrate that background estimation can be nontrivial by comparing the results of different background estimation procedures by using data obtained from a CCD array detector. We investigate the temperature-dependent contributions of the detector and readout electronics to the total signal as a demonstration of the diagnostic capabilities of least-squares image regression.

  14. Detailed Radio Imaging of a CME with the Murchison Widefield Array

    Science.gov (United States)

    Kozarev, Kamen; Oberoi, Divya; Morgan, John; Crowley, Meagan; Benkevitch, Leonid; Lonsdale, Colin; McCauley, Patrick; Winter, Henry; Cairns, Iver

    2017-04-01

    Solar radio observations allow us to constrain the dynamics of high energy electron beams accelerated in both flares and coronal mass ejections (CME). In particular, the synchrotron emission from erupting flux ropes should give important information about the distributions of energetic electrons trapped in the cores of CMEs. The Murchison Widefield Array is one of several new radio interferometric instruments, and is particularly well-suited to imaging the Sun and solar transients at multiple frequency channels between 80 and 300 MHz. This instrument holds great promise for improving the status of direct CME imaging in the radio. Here we present imaging observations with high frequency and time resolution of a CME, which occurred on November 4, 2015. The observations allow us to obtain detailed frequency spectra of the plasma and synchrotron emission. In addition, such observations may provide independent information about the thermal electron density, as well as the magnetic field strength in the CME flux rope. Finally, these observations provide information about the detailed evolution and kinematics of the CME and its flux rope in its early stages. The new observations demonstrate the capability of the MWA to contribute to the monitoring and detailed analysis of solar eruptions through its high sensitivity, high dynamic range radio imaging.

  15. Photon Counting Energy Dispersive Detector Arrays for X-ray Imaging

    Science.gov (United States)

    Iwanczyk, Jan S.; Nygård, Einar; Meirav, Oded; Arenson, Jerry; Barber, William C.; Hartsough, Neal E.; Malakhov, Nail; Wessel, Jan C.

    2009-01-01

    The development of an innovative detector technology for photon-counting in X-ray imaging is reported. This new generation of detectors, based on pixellated cadmium telluride (CdTe) and cadmium zinc telluride (CZT) detector arrays electrically connected to application specific integrated circuits (ASICs) for readout, will produce fast and highly efficient photon-counting and energy-dispersive X-ray imaging. There are a number of applications that can greatly benefit from these novel imagers including mammography, planar radiography, and computed tomography (CT). Systems based on this new detector technology can provide compositional analysis of tissue through spectroscopic X-ray imaging, significantly improve overall image quality, and may significantly reduce X-ray dose to the patient. A very high X-ray flux is utilized in many of these applications. For example, CT scanners can produce ~100 Mphotons/mm2/s in the unattenuated beam. High flux is required in order to collect sufficient photon statistics in the measurement of the transmitted flux (attenuated beam) during the very short time frame of a CT scan. This high count rate combined with a need for high detection efficiency requires the development of detector structures that can provide a response signal much faster than the transit time of carriers over the whole detector thickness. We have developed CdTe and CZT detector array structures which are 3 mm thick with 16×16 pixels and a 1 mm pixel pitch. These structures, in the two different implementations presented here, utilize either a small pixel effect or a drift phenomenon. An energy resolution of 4.75% at 122 keV has been obtained with a 30 ns peaking time using discrete electronics and a 57Co source. An output rate of 6×106 counts per second per individual pixel has been obtained with our ASIC readout electronics and a clinical CT X-ray tube. Additionally, the first clinical CT images, taken with several of our prototype photon-counting and energy

  16. Technical Note: Rapid prototyping of 3D grid arrays for image guided therapy quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Kittle, David; Holshouser, Barbara; Slater, James M.; Guenther, Bob D.; Pitsianis, Nikos P.; Pearlstein, Robert D. [Department of Radiation Medicine, Epilepsy Radiosurgery Research Program, Loma Linda University, Loma Linda, California 92354 (United States); Department of Radiology, Loma Linda University Medical Center, Loma Linda, California 92354 (United States); Department of Radiation Medicine, Loma Linda University, Loma Linda, California 92354 (United States); Department of Physics, Duke University, Durham, North Carolina 27708 (United States); Department of Electrical and Computer Engineering and Department of Computer Science, Duke University, Durham, North Carolina 27708 (United States); Department of Radiation Medicine, Epilepsy Radiosurgery Research Program, Loma Linda University, Loma Linda, California 92354 and Department of Surgery-Neurosurgery, Duke University and Medical Center, Durham, North Carolina 27710 (United States)

    2008-12-15

    Three dimensional grid phantoms offer a number of advantages for measuring imaging related spatial inaccuracies for image guided surgery and radiotherapy. The authors examined the use of rapid prototyping technology for directly fabricating 3D grid phantoms from CAD drawings. We tested three different fabrication process materials, photopolymer jet with acrylic resin (PJ/AR), selective laser sintering with polyamide (SLS/P), and fused deposition modeling with acrylonitrile butadiene styrene (FDM/ABS). The test objects consisted of rectangular arrays of control points formed by the intersections of posts and struts (2 mm rectangular cross section) and spaced 8 mm apart in the x, y, and z directions. The PJ/AR phantom expanded after immersion in water which resulted in permanent warping of the structure. The surface of the FDM/ABS grid exhibited a regular pattern of depressions and ridges from the extrusion process. SLS/P showed the best combination of build accuracy, surface finish, and stability. Based on these findings, a grid phantom for assessing machine-dependent and frame-induced MR spatial distortions was fabricated to be used for quality assurance in stereotactic neurosurgical and radiotherapy procedures. The spatial uniformity of the SLS/P grid control point array was determined by CT imaging (0.6x0.6x0.625 mm{sup 3} resolution) and found suitable for the application, with over 97.5% of the control points located within 0.3 mm of the position specified in CAD drawing and none of the points off by more than 0.4 mm. Rapid prototyping is a flexible and cost effective alternative for development of customized grid phantoms for medical physics quality assurance.

  17. High-speed X-ray imaging pixel array detector for synchrotron bunch isolation

    Energy Technology Data Exchange (ETDEWEB)

    Philipp, Hugh T., E-mail: htp2@cornell.edu; Tate, Mark W.; Purohit, Prafull; Shanks, Katherine S.; Weiss, Joel T. [Cornell University, Ithaca, NY 14853 (United States); Gruner, Sol M. [Cornell University, Ithaca, NY 14853 (United States); Cornell University, Ithaca, NY 14853 (United States)

    2016-01-28

    A high-speed pixel array detector for time-resolved X-ray imaging at synchrotrons has been developed. The ability to isolate single synchrotron bunches makes it ideal for time-resolved dynamical studies. A wide-dynamic-range imaging X-ray detector designed for recording successive frames at rates up to 10 MHz is described. X-ray imaging with frame rates of up to 6.5 MHz have been experimentally verified. The pixel design allows for up to 8–12 frames to be stored internally at high speed before readout, which occurs at a 1 kHz frame rate. An additional mode of operation allows the integration capacitors to be re-addressed repeatedly before readout which can enhance the signal-to-noise ratio of cyclical processes. This detector, along with modern storage ring sources which provide short (10–100 ps) and intense X-ray pulses at megahertz rates, opens new avenues for the study of rapid structural changes in materials. The detector consists of hybridized modules, each of which is comprised of a 500 µm-thick silicon X-ray sensor solder bump-bonded, pixel by pixel, to an application-specific integrated circuit. The format of each module is 128 × 128 pixels with a pixel pitch of 150 µm. In the prototype detector described here, the three-side buttable modules are tiled in a 3 × 2 array with a full format of 256 × 384 pixels. The characteristics, operation, testing and application of the detector are detailed.

  18. Highly accelerated acquisition and homogeneous image reconstruction with rotating RF coil array at 7T-A phantom based study.

    Science.gov (United States)

    Li, Mingyan; Zuo, Zhentao; Jin, Jin; Xue, Rong; Trakic, Adnan; Weber, Ewald; Liu, Feng; Crozier, Stuart

    2014-03-01

    Parallel imaging (PI) is widely used for imaging acceleration by means of coil spatial sensitivities associated with phased array coils (PACs). By employing a time-division multiplexing technique, a single-channel rotating radiofrequency coil (RRFC) provides an alternative method to reduce scan time. Strategically combining these two concepts could provide enhanced acceleration and efficiency. In this work, the imaging acceleration ability and homogeneous image reconstruction strategy of 4-element rotating radiofrequency coil array (RRFCA) was numerically investigated and experimental validated at 7T with a homogeneous phantom. Each coil of RRFCA was capable of acquiring a large number of sensitivity profiles, leading to a better acceleration performance illustrated by the improved geometry-maps that have lower maximum values and more uniform distributions compared to 4- and 8-element stationary arrays. A reconstruction algorithm, rotating SENSitivity Encoding (rotating SENSE), was proposed to provide image reconstruction. Additionally, by optimally choosing the angular sampling positions and transmit profiles under the rotating scheme, phantom images could be faithfully reconstructed. The results indicate that, the proposed technique is able to provide homogeneous reconstructions with overall higher and more uniform signal-to-noise ratio (SNR) distributions at high reduction factors. It is hoped that, by employing the high imaging acceleration and homogeneous imaging reconstruction ability of RRFCA, the proposed method will facilitate human imaging for ultra high field MRI. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Imaging method for downward-looking sparse linear array three-dimensional synthetic aperture radar based on reweighted atomic norm

    Science.gov (United States)

    Bao, Qian; Han, Kuoye; Lin, Yun; Zhang, Bingchen; Liu, Jianguo; Hong, Wen

    2016-01-01

    We propose an imaging algorithm for downward-looking sparse linear array three-dimensional synthetic aperture radar (DLSLA 3-D SAR) in the circumstance of cross-track sparse and nonuniform array configuration. Considering the off-grid effect and the resolution improvement, the algorithm combines pseudo-polar formatting algorithm, reweighed atomic norm minimization (RANM), and a parametric relaxation-based cyclic approach (RELAX) to improve the imaging performance with a reduced number of array antennas. RANM is employed in the cross-track imaging after pseudo-polar formatting the DLSLA 3-D SAR echo signal, then the reconstructed results are refined by RELAX. By taking advantage of the reweighted scheme, RANM can improve the resolution of the atomic norm minimization, and outperforms discretized compressive sensing schemes that suffer from off-grid effect. The simulated and real data experiments of DLSLA 3-D SAR verify the performance of the proposed algorithm.

  20. High-Resolution Spin-on-Patterning of Perovskite Thin Films for a Multiplexed Image Sensor Array.

    Science.gov (United States)

    Lee, Woongchan; Lee, Jongha; Yun, Huiwon; Kim, Joonsoo; Park, Jinhong; Choi, Changsoon; Kim, Dong Chan; Seo, Hyunseon; Lee, Hakyong; Yu, Ji Woong; Lee, Won Bo; Kim, Dae-Hyeong

    2017-10-01

    Inorganic-organic hybrid perovskite thin films have attracted significant attention as an alternative to silicon in photon-absorbing devices mainly because of their superb optoelectronic properties. However, high-definition patterning of perovskite thin films, which is important for fabrication of the image sensor array, is hardly accomplished owing to their extreme instability in general photolithographic solvents. Here, a novel patterning process for perovskite thin films is described: the high-resolution spin-on-patterning (SoP) process. This fast and facile process is compatible with a variety of spin-coated perovskite materials and perovskite deposition techniques. The SoP process is successfully applied to develop a high-performance, ultrathin, and deformable perovskite-on-silicon multiplexed image sensor array, paving the road toward next-generation image sensor arrays. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Rupture Imaging of the 12 May 2008 Wenchuan Earthquake Using Teleseismic Arrays

    Science.gov (United States)

    Xu, Y.; Koper, K. D.; Sufri, O.

    2008-12-01

    In this work we constrain the source properties of the 7.9 Mw Wenchuan earthquake by back-projecting teleseismic P energy from virtual seismic arrays. Using the IRIS DMC, we collected 255 broadband P waves at 30-90 degrees from the epicenter. We applied a multi-channel cross-correlation algorithm and found that at periods > 5 s nearly all of the station averaged correlation coefficients were above 0.9. We used a genetic algorithm to search for sets of station weights that yielded array response functions (ARFs) with symmetric, narrow mainlobes and small sidelobes at a period of 5 s; however, none of them were significantly better than those derived from a simple downsampling heuristic in which we randomly selected a single station from each 1000 km by 1000 km patch on the Earth's surface. We also considered three regional subarrays in Alaska, Australia, and Europe with apertures less than 30 degrees. Coherence observations implied that these arrays would be effective to periods of 1-2 s. Individual ARFs for the regional subarrays were skewed towards the seismometers, however the linear sum of the regional subarray beams at 1 s produced a symmetric ARF similar to that of the groomed global subarray at 5 s. We considered three measures of beam power in constructing the rupture images: linear, Nth root, and F stacking. We found that F stacking was best for detecting the beginning and duration of the rupture, but that it produced the most biased relative amplitudes among patches of energy release. Linear stacking showed relative amplitudes that agreed with the finite fault results, but it gave the poorest spatial resolution. The Nth root stacks (with N=4) worked the best overall, showing consistent relative amplitudes with high spatial resolution. The spatial distribution of energy release imaged by the global subarray at 5 s is slightly different than that imaged by the combination of three regional subarrays at 1 s, which may indicate some frequency dependence to the

  2. Calibration and Stokes Imaging with Full Embedded Element Primary Beam Model for the Murchison Widefield Array

    Science.gov (United States)

    Sokolowski, M.; Colegate, T.; Sutinjo, A. T.; Ung, D.; Wayth, R.; Hurley-Walker, N.; Lenc, E.; Pindor, B.; Morgan, J.; Kaplan, D. L.; Bell, M. E.; Callingham, J. R.; Dwarakanath, K. S.; For, Bi-Qing; Gaensler, B. M.; Hancock, P. J.; Hindson, L.; Johnston-Hollitt, M.; Kapińska, A. D.; McKinley, B.; Offringa, A. R.; Procopio, P.; Staveley-Smith, L.; Wu, C.; Zheng, Q.

    2017-11-01

    The Murchison Widefield Array (MWA), located in Western Australia, is one of the low-frequency precursors of the international Square Kilometre Array (SKA) project. In addition to pursuing its own ambitious science programme, it is also a testbed for wide range of future SKA activities ranging from hardware, software to data analysis. The key science programmes for the MWA and SKA require very high dynamic ranges, which challenges calibration and imaging systems. Correct calibration of the instrument and accurate measurements of source flux densities and polarisations require precise characterisation of the telescope's primary beam. Recent results from the MWA GaLactic Extragalactic All-sky Murchison Widefield Array (GLEAM) survey show that the previously implemented Average Embedded Element (AEE) model still leaves residual polarisations errors of up to 10-20% in Stokes Q. We present a new simulation-based Full Embedded Element (FEE) model which is the most rigorous realisation yet of the MWA's primary beam model. It enables efficient calculation of the MWA beam response in arbitrary directions without necessity of spatial interpolation. In the new model, every dipole in the MWA tile (4 × 4 bow-tie dipoles) is simulated separately, taking into account all mutual coupling, ground screen, and soil effects, and therefore accounts for the different properties of the individual dipoles within a tile. We have applied the FEE beam model to GLEAM observations at 200-231 MHz and used false Stokes parameter leakage as a metric to compare the models. We have determined that the FEE model reduced the magnitude and declination-dependent behaviour of false polarisation in Stokes Q and V while retaining low levels of false polarisation in Stokes U.

  3. Higher moments of scattered light fields by heterodyne analysis

    Science.gov (United States)

    Harris, M.; Paerson, G. N.; Hill, C. A.; Vaughan, J. M.

    1994-10-01

    A simple scattering experiment employing heterodyne detection and operating in Gaussian scattering regime (with large number of illuminated independent scatterers) is shown to yield experimental values of higher-order moments of scattered light intensity distribution in agreement with theoretical predictions. This permits assessment of Gaussian behavior. Laser light scattering from a rotating glass screen is used in the study.

  4. Ultrasound Nondestructive Evaluation (NDE Imaging with Transducer Arrays and Adaptive Processing

    Directory of Open Access Journals (Sweden)

    Minghui Li

    2011-12-01

    Full Text Available This paper addresses the challenging problem of ultrasonic non-destructive evaluation (NDE imaging with adaptive transducer arrays. In NDE applications, most materials like concrete, stainless steel and carbon-reinforced composites used extensively in industries and civil engineering exhibit heterogeneous internal structure. When inspected using ultrasound, the signals from defects are significantly corrupted by the echoes form randomly distributed scatterers, even defects that are much larger than these random reflectors are difficult to detect with the conventional delay-and-sum operation. We propose to apply adaptive beamforming to the received data samples to reduce the interference and clutter noise. Beamforming is to manipulate the array beam pattern by appropriately weighting the per-element delayed data samples prior to summing them. The adaptive weights are computed from the statistical analysis of the data samples. This delay-weight-and-sum process can be explained as applying a lateral spatial filter to the signals across the probe aperture. Simulations show that the clutter noise is reduced by more than 30 dB and the lateral resolution is enhanced simultaneously when adaptive beamforming is applied. In experiments inspecting a steel block with side-drilled holes, good quantitative agreement with simulation results is demonstrated.

  5. Ultrasound nondestructive evaluation (NDE) imaging with transducer arrays and adaptive processing.

    Science.gov (United States)

    Li, Minghui; Hayward, Gordon

    2012-01-01

    This paper addresses the challenging problem of ultrasonic non-destructive evaluation (NDE) imaging with adaptive transducer arrays. In NDE applications, most materials like concrete, stainless steel and carbon-reinforced composites used extensively in industries and civil engineering exhibit heterogeneous internal structure. When inspected using ultrasound, the signals from defects are significantly corrupted by the echoes form randomly distributed scatterers, even defects that are much larger than these random reflectors are difficult to detect with the conventional delay-and-sum operation. We propose to apply adaptive beamforming to the received data samples to reduce the interference and clutter noise. Beamforming is to manipulate the array beam pattern by appropriately weighting the per-element delayed data samples prior to summing them. The adaptive weights are computed from the statistical analysis of the data samples. This delay-weight-and-sum process can be explained as applying a lateral spatial filter to the signals across the probe aperture. Simulations show that the clutter noise is reduced by more than 30 dB and the lateral resolution is enhanced simultaneously when adaptive beamforming is applied. In experiments inspecting a steel block with side-drilled holes, good quantitative agreement with simulation results is demonstrated.

  6. Summary of the operational land imager focal plane array for the Landsat Data Continuity Mission

    Science.gov (United States)

    Lindahl, Kirk A.; Burmester, William; Malone, Kevin; Schrein, Ronald J.; Irwin, Ronda; Donley, Eric; Collins, Sandra R.

    2011-10-01

    The Landsat missions are the longest continuous record of changes in the Earth's surface as seen from space. The next follow-on activity is the Landsat Data Continuity Mission (LDCM). The LDCM objective is to extend the ability to detect and quantitatively characterize changes on the global land surface at a scale where natural and man-made causes of change can be detected and differentiated. The Operational Land Imager (OLI) is one of two instruments on the LDCM spacecraft. OLI will produce science data for the reflective bands, which include 6 visible and near-infrared (VNIR) and 3 short-wave infrared (SWIR) bands. The OLI instrument utilizes a pushbroom design with 15.5 degree field of view. As a result, the OLI Focal Plane Array (FPA) cross track dimension is large, and the FPA is a critical technology for the success of the mission. The FPA contains 14 critically aligned Focal Plane Modules (FPM) and consists of 6916 imaging pixels in each of the 8 multi-spectral bands, and 13,832 imaging pixels in the panchromatic band. Prior to integration into the FPA, the FPMs were characterized for radiometric, spectral, and spatial performance. The Flight FPA has been built and its performance has also been characterized. In this paper, the critical attributes of the FPMs and FPA are highlighted. Detailed description of the FPM and FPA test sets are provided. The performance results that demonstrate compliance to the science mission requirements are presented.

  7. Intensity Interferometry with Cherenkov Telescope Arrays: Prospects for submilliarcsecond optical imaging

    Science.gov (United States)

    Dravins, D.

    2014-04-01

    Intensity interferometry measures the second-order coherence of light. Very rapid (nanosecond) fluctuations are correlated between separate telescopes, without any optical connection. This makes the method insensitive to atmospheric turbulence and optical imperfections, permitting observations over long baselines, and at short wavelengths. The required large telescopes are becoming available as those primarily erected to study gamma rays: the planned Cherenkov Telescope Array (https://www.cta-observatory.org/) envisions many tens of telescopes distributed over a few square km. Digital signal handling enables very many baselines to be simultaneously synthesized between many pairs of telescopes, while stars may be tracked across the sky with electronic time delays, synthesizing an optical interferometer in software. Simulations indicate limiting magnitudes around m(v)=8, reaching a resolution of 30 microarcseconds in the violet. Since intensity interferometry provides only the modulus (not phase) of any spatial frequency component of the source image, image reconstruction requires phase retrieval techniques. As shown in simulations, full two-dimensional images can be retrieved, provided there is an extensive coverage of the (u,v)-plane, such as will be available once the number of telescopes reaches numbers on the order of ten.

  8. Using field programmable gate array hardware for the performance improvement of ultrasonic wave propagation imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Shan, Jaffry Syed [Hamdard University, Karachi (Pakistan); Abbas, Syed Haider; Lee, Jung Ryul [Dept. of Aerospace Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kang, Dong Hoon [Advanced Materials Research Team, Korea Railroad Research Institute, Uiwang (Korea, Republic of)

    2015-12-15

    Recently, wave propagation imaging based on laser scanning-generated elastic waves has been intensively used for nondestructive inspection. However, the proficiency of the conventional software based system reduces when the scan area is large since the processing time increases significantly due to unavoidable processor multitasking, where computing resources are shared with multiple processes. Hence, the field programmable gate array (FPGA) was introduced for a wave propagation imaging method in order to obtain extreme processing time reduction. An FPGA board was used for the design, implementing post-processing ultrasonic wave propagation imaging (UWPI). The results were compared with the conventional system and considerable improvement was observed, with at least 78% (scanning of 100x100mm{sup 2} with 0.5 mm interval) to 87.5% (scanning of 200x200mm{sup 2} with 0.5 mm interval) less processing time, strengthening the claim for the research. This new concept to implement FPGA technology into the UPI system will act as a break-through technology for full-scale automatic inspection.

  9. Thermal imager based on the array light sensor device of 128×128 CdHgTe-photodiodes

    Directory of Open Access Journals (Sweden)

    Reva V. P.

    2010-08-01

    Full Text Available The results of investigation of developed thermal imager for middle (3—5 µm infrared region are presented and its applications features are discussed. The thermal imager consists of cooled to 80 K 128×128 diodes focal plane array on the base of cadmium–mercury–telluride compound and cryostat with temperature checking system. The photodiode array is bonded with readout device (silicon focal processor via indium microcontacts. The measured average value of noise equivalent temperature difference was NETD= 20±4 mK (background radiation temperature T = 300 K, field of view 2θ = 180°, the cooled diaphragm was not used.

  10. Optical Demonstration of a Medical Imaging System with an EMCCD-Sensor Array for Use in a High Resolution Dynamic X-ray Imager.

    Science.gov (United States)

    Qu, Bin; Huang, Ying; Wang, Weiyuan; Sharma, Prateek; Kuhls-Gilcrist, Andrew T; Cartwright, Alexander N; Titus, Albert H; Bednarek, Daniel R; Rudin, Stephen

    2010-10-30

    Use of an extensible array of Electron Multiplying CCDs (EMCCDs) in medical x-ray imager applications was demonstrated for the first time. The large variable electronic-gain (up to 2000) and small pixel size of EMCCDs provide effective suppression of readout noise compared to signal, as well as high resolution, enabling the development of an x-ray detector with far superior performance compared to conventional x-ray image intensifiers and flat panel detectors. We are developing arrays of EMCCDs to overcome their limited field of view (FOV). In this work we report on an array of two EMCCD sensors running simultaneously at a high frame rate and optically focused on a mammogram film showing calcified ducts. The work was conducted on an optical table with a pulsed LED bar used to provide a uniform diffuse light onto the film to simulate x-ray projection images. The system can be selected to run at up to 17.5 frames per second or even higher frame rate with binning. Integration time for the sensors can be adjusted from 1 ms to 1000 ms. Twelve-bit correlated double sampling AD converters were used to digitize the images, which were acquired by a National Instruments dual-channel Camera Link PC board in real time. A user-friendly interface was programmed using LabVIEW to save and display 2K × 1K pixel matrix digital images. The demonstration tiles a 2 × 1 array to acquire increased-FOV stationary images taken at different gains and fluoroscopic-like videos recorded by scanning the mammogram simultaneously with both sensors. The results show high resolution and high dynamic range images stitched together with minimal adjustments needed. The EMCCD array design allows for expansion to an M×N array for arbitrarily larger FOV, yet with high resolution and large dynamic range maintained.

  11. Synaptic molecular imaging in spared and deprived columns of mouse barrel cortex with array tomography.

    Science.gov (United States)

    Weiler, Nicholas C; Collman, Forrest; Vogelstein, Joshua T; Burns, Randal; Smith, Stephen J

    2014-01-01

    A major question in neuroscience is how diverse subsets of synaptic connections in neural circuits are affected by experience dependent plasticity to form the basis for behavioral learning and memory. Differences in protein expression patterns at individual synapses could constitute a key to understanding both synaptic diversity and the effects of plasticity at different synapse populations. Our approach to this question leverages the immunohistochemical multiplexing capability of array tomography (ATomo) and the columnar organization of mouse barrel cortex to create a dataset comprising high resolution volumetric images of spared and deprived cortical whisker barrels stained for over a dozen synaptic molecules each. These dataset has been made available through the Open Connectome Project for interactive online viewing, and may also be downloaded for offline analysis using web, Matlab, and other interfaces.

  12. Hybrid Si nanowire/amorphous silicon FETs for large-area image sensor arrays.

    Science.gov (United States)

    Wong, William S; Raychaudhuri, Sourobh; Lujan, René; Sambandan, Sanjiv; Street, Robert A

    2011-06-08

    Silicon nanowire (SiNW) field-effect transistors (FETs) were fabricated from nanowire mats mechanically transferred from a donor growth wafer. Top- and bottom-gate FET structures were fabricated using a doped a-Si:H thin film as the source/drain (s/d) contact. With a graded doping profile for the a-Si:H s/d contacts, the off-current for the hybrid nanowire/thin-film devices was found to decrease by 3 orders of magnitude. Devices with the graded contacts had on/off ratios of ∼10(5), field-effect mobility of ∼50 cm(2)/(V s), and subthreshold swing of 2.5 V/decade. A 2 in. diagonal 160 × 180 pixel image sensor array was fabricated by integrating the SiNW backplane with an a-Si:H p-i-n photodiode.

  13. A comparison between ultrasonic array beamforming and super resolution imaging algorithms for non-destructive evaluation.

    Science.gov (United States)

    Fan, Chengguang; Caleap, Mihai; Pan, Mengchun; Drinkwater, Bruce W

    2014-09-01

    In this paper the total focusing method, the so called gold standard in classical beamforming, is compared with the widely used time-reversal MUSIC super resolution technique in terms of its ability to resolve closely spaced scatterers in a solid. The algorithms are tested with simulated and experimental array data, each containing different noise levels. The performance of the algorithms is evaluated in terms of lateral resolution and sensitivity to noise. It is shown that for the weak noise situation (SNR>20 dB), time-reversal MUSIC provides significantly enhanced lateral resolution when compared to the total focusing method, breaking the diffraction limit. However, for higher noise levels, the total focusing method is shown to be robust, whilst the performance of time-reversal MUSIC is degraded. The influence of multiple scattering on the imaging algorithms is also investigated and shown to be small. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  14. Non-Destructive Spent Fuel Characterization with Semi-Conducting Gallium Arsinde Neutron Imaging Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Douglas S. McGregor; Holly K. Gersch; Jeffrey D. Sanders; John C. Lee; Mark D. Hammig; Michael R. Hartman; Yong Hong Yang; Raymond T. Klann; Brian Van Der Elzen; John T. Lindsay; Philip A. Simpson

    2002-01-30

    High resistivity bulk grown GaAs has been used to produce thermal neutron imaging devices for use in neutron radiography and characterizing burnup in spent fuel. The basic scheme utilizes a portable Sb/Be source for monoenergetic (24 keV) neutron radiation source coupled to an Fe filter with a radiation hard B-coated pixellated GaAs detector array as the primary neutron detector. The coated neutron detectors have been tested for efficiency and radiation hardness in order to determine their fitness for the harsh environments imposed by spent fuel. Theoretical and experimental results are presented, showing detector radiation hardness, expected detection efficiency and the spatial resolution from such a scheme. A variety of advanced neutron detector designs have been explored, with experimental results achieving 13% thermal neutron detection efficiency while projecting the possibility of over 30% thermal neutron detection efficiency.

  15. Ordered arrays of native chromatin molecules for high-resolution imaging and analysis.

    Science.gov (United States)

    Cerf, Aline; Tian, Harvey C; Craighead, Harold G

    2012-09-25

    Individual chromatin molecules contain valuable genetic and epigenetic information. To date, there have not been reliable techniques available for the controlled stretching and manipulation of individual chromatin fragments for high-resolution imaging and analysis of these molecules. We report the controlled stretching of single chromatin fragments extracted from two different cancerous cell types (M091 and HeLa) characterized through fluorescence microscopy and atomic force microscopy (AFM). Our method combines soft lithography with molecular stretching to form ordered arrays of more than 250,000 individual chromatin fragments immobilized into a beads-on-a-string structure on a solid transparent support. Using fluorescence microscopy and AFM, we verified the presence of histone proteins after the stretching and transfer process.

  16. Comparative study of sampling strategies for sparse photon multispectral lidar imaging: towards mosaic filter arrays

    Science.gov (United States)

    Tobin, Rachael; Altmann, Yoann; Ren, Ximing; McCarthy, Aongus; Lamb, Robert A.; McLaughlin, Stephen; Buller, Gerald S.

    2017-09-01

    In this paper, we investigate the recovery of range and spectral profiles associated with remote three-dimensional scenes sensed via single-photon multispectral lidar (MSL). We consider two different spatial/spectral sampling strategies and compare their performance for a similar overall number of detected photons. For a regular spatial grid of pixels, the first strategy consists of sampling all the spatial locations of the grid for each of the L wavelengths. The second strategy is consistent with the use of mosaic filter-based arrays and consists of acquiring only one wavelength (out of L) per spatial location. Despite the reduction of spectral content observed in each location, the second strategy has clear potential advantages for fast multispectral imaging using only a single frame read out. We propose a fully automated computational method, adapted for each of the two sampling strategies in order to recover the target range profile, as well as the reflectivity profiles associated with the different wavelengths. These strategies were also assessed with high ambient background. The performance of the two sampling strategies is illustrated using a single-photon MSL system with L = 4 wavelengths (473, 532, 589 and 640 nm). The results presented demonstrate that although the first strategy usually provides more accurate results, the second strategy does not exhibit a significant performance degradation, particularly for sparse photon data (down to 1 photon per pixel on average). These results suggest a way forward for the integration of single-photon detector arrays with mosaic filters for use in a range of emerging photon-starved two-dimensional and three-dimensional imaging applications.

  17. Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System

    Directory of Open Access Journals (Sweden)

    Jong-Ryul Yang

    2016-03-01

    Full Text Available A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s.

  18. Smart-phone based computational microscopy using multi-frame contact imaging on a fiber-optic array

    Science.gov (United States)

    Navruz, Isa; Coskun, Ahmet F.; Wong, Justin; Mohammad, Saqib; Tseng, Derek; Nagi, Richie; Phillips, Stephen; Ozcan, Aydogan

    2013-01-01

    We demonstrate a cellphone based contact microscopy platform, termed Contact Scope, which can image highly dense or connected samples in transmission mode. Weighing approximately 76 grams, this portable and compact microscope is installed on the existing camera unit of a cellphone using an opto-mechanical add-on, where planar samples of interest are placed in contact with the top facet of a tapered fiber-optic array. This glass-based tapered fiber array has ∼9 fold higher density of fiber optic cables on its top facet compared to the bottom one and is illuminated by an incoherent light source, e.g., a simple light-emitting-diode (LED). The transmitted light pattern through the object is then sampled by this array of fiber optic cables, delivering a transmission image of the sample onto the other side of the taper, with ∼3× magnification in each direction. This magnified image of the object, located at the bottom facet of the fiber array, is then projected onto the CMOS image sensor of the cellphone using two lenses. While keeping the sample and the cellphone camera at a fixed position, the fiber-optic array is then manually rotated with discrete angular increments of e.g., 1-2 degrees. At each angular position of the fiber-optic array, contact images are captured using the cellphone camera, creating a sequence of transmission images for the same sample. These multi-frame images are digitally fused together based on a shift-and-add algorithm through a custom-developed Android application running on the smart-phone, providing the final microscopic image of the sample, visualized through the screen of the phone. This final computation step improves the resolution and also gets rid of spatial artefacts that arise due to non-uniform sampling of the transmission intensity at the fiber optic array surface. We validated the performance of this cellphone based Contact Scope by imaging resolution test charts and blood smears. PMID:23939637

  19. MMW/THz imaging using upconversion to visible, based on glow discharge detector array and CCD camera

    Science.gov (United States)

    Aharon, Avihai; Rozban, Daniel; Abramovich, Amir; Yitzhaky, Yitzhak; Kopeika, Natan S.

    2017-10-01

    An inexpensive upconverting MMW/THz imaging method is suggested here. The method is based on glow discharge detector (GDD) and silicon photodiode or simple CCD/CMOS camera. The GDD was previously found to be an excellent room-temperature MMW radiation detector by measuring its electrical current. The GDD is very inexpensive and it is advantageous due to its wide dynamic range, broad spectral range, room temperature operation, immunity to high power radiation, and more. An upconversion method is demonstrated here, which is based on measuring the visual light emitting from the GDD rather than its electrical current. The experimental setup simulates a setup that composed of a GDD array, MMW source, and a basic CCD/CMOS camera. The visual light emitting from the GDD array is directed to the CCD/CMOS camera and the change in the GDD light is measured using image processing algorithms. The combination of CMOS camera and GDD focal plane arrays can yield a faster, more sensitive, and very inexpensive MMW/THz camera, eliminating the complexity of the electronic circuits and the internal electronic noise of the GDD. Furthermore, three dimensional imaging systems based on scanning prohibited real time operation of such imaging systems. This is easily solved and is economically feasible using a GDD array. This array will enable us to acquire information on distance and magnitude from all the GDD pixels in the array simultaneously. The 3D image can be obtained using methods like frequency modulation continuous wave (FMCW) direct chirp modulation, and measuring the time of flight (TOF).

  20. Comparison of Thermal Detector Arrays for Off-Axis THz Holography and Real-Time THz Imaging

    Directory of Open Access Journals (Sweden)

    Erwin Hack

    2016-02-01

    Full Text Available In terahertz (THz materials science, imaging by scanning prevails when low power THz sources are used. However, the application of array detectors operating with high power THz sources is increasingly reported. We compare the imaging properties of four different array detectors that are able to record THz radiation directly. Two micro-bolometer arrays are designed for infrared imaging in the 8–14 μm wavelength range, but are based on different absorber materials (i vanadium oxide; (ii amorphous silicon; (iii a micro-bolometer array optimized for recording THz radiation based on silicon nitride; and (iv a pyroelectric array detector for THz beam profile measurements. THz wavelengths of 96.5 μm, 118.8 μm, and 393.6 μm from a powerful far infrared laser were used to assess the technical performance in terms of signal to noise ratio, detector response and detectivity. The usefulness of the detectors for beam profiling and digital holography is assessed. Finally, the potential and limitation for real-time digital holography are discussed.

  1. Influence of the number of basis images and projection array on caries detection using tuned aperture computed tomography (TACT).

    Science.gov (United States)

    Abreu, M; Tyndall, D A; Ludlow, J B; Nortjé, C J

    2002-01-01

    to determine if the number of basis images and spatial distribution of the projection array used for TACT slice generation influence observer performance in caries detection. In the first experiment, 2, 4, 8 and 12 basis projections of each of 40 teeth were acquired using a CMOS digital radiography sensor. Projections were distributed radially in space using a 20 degree angular disparity. TACT slices were generated from the four subgroups of images, presented to eight observers, and viewed on a high-resolution monitor. Observers scored the presence/absence of caries using a 5-point confidence scale. Gold standard was histological examination of tooth sections. ROC curves measured observer diagnostic performance. ANOVA tested for significant differences between observers and experimental conditions. In the second experiment, the number of basis projections judged to be satisfactory for TACT slice generation was used. Horizontal and vertical linear arrays of projections were compared to the circular projection array. There was a statistically significant difference between the numbers of basis projections in the detection of both occlusal (P=0.006) and proximal caries (P=0.005). No significant difference was found between projection arrays in the detection of either occlusal (P=0.065) or proximal (P=0.515) caries. The number of TACT basis projections significantly influences caries detection. Eight or more images should be used. Either linear-vertical, linear-horizontal or circular arrays of basis projections may be used for TACT slice generation in caries detection tasks.

  2. Dual-mode ultrasound arrays for image-guided targeting of atheromatous plaques

    Science.gov (United States)

    Ballard, John R.; Casper, Andrew J.; Liu, Dalong; Haritonova, Alyona; Shehata, Islam A.; Troutman, Mitchell; Ebbini, Emad S.

    2012-11-01

    A feasibility study was undertaken in order to investigate alternative noninvasive treatment options for atherosclerosis. In particular, the aim of this study was to investigate the potential use of Dual-Mode Ultrasound Arrays (DMUAs) for image guided treatment of atheromatous plaques. DMUAs offer a unique treatment paradigm for image-guided surgery allowing for robust image-based identification of tissue targets for localized application of HIFU. In this study we present imaging and therapeutic results form a 3.5 MHz, 64-element fenestrated prototype DMUA for targeting lesions in the femoral artery of familial hypercholesterolemic (FH) swine. Before treatment, diagnostic ultrasound was used to verify the presence of plaque in the femoral artery of the swine. Images obtained with the DMUA and a diagnostic (HST 15-8) transducer housed in the fenestration were analyzed and used for guidance in targeting of the plaque. Discrete therapeutic shots with an estimated focal intensity of 4000-5600 W/cm2 and 500-2000 msec duration were performed at several planes in the plaque. During therapy, pulsed HIFU was interleaved with single transmit focus imaging from the DMUA and M2D imaging from the diagnostic transducer for further analysis of lesion formation. After therapy, the swine's were recovered and later sacrificed after 4 and 7 days for histological analysis of lesion formation. At sacrifice, the lower half of the swine was perfused and the femoral artery with adjoining muscle was fixed and stained with H&E to characterize HIFU-induced lesions. Histology has confirmed that localized thermal lesion formation within the plaque was achieved according to the planned lesion maps. Furthermore, the damage was confined to the plaque tissue without damage to the intima. These results offer the promise of a new treatment potentially suited for vulnerable plaques. The results also provide the first real-time demonstration of DMUA technology in targeting fine tissue structures for

  3. Single beam write and/or replay of spatial heterodyne holograms

    Science.gov (United States)

    Thomas, Clarence E.; Hanson, Gregory R.

    2007-11-20

    A method of writing a spatially heterodyne hologram having spatially heterodyne fringes includes: passing a single write beam through a spatial light modulator that digitally modulates said single write beam; and focusing the single write beam at a focal plane of a lens to impose a holographic diffraction grating pattern on the photorefractive crystal, the holographic diffraction grating pattern including the spatially heterodyne hologram having spatially heterodyne fringes, wherein only said single write beam is incident on said photorefractive crystal without a reference beam. A method of replaying a spatially heterodyne hologram having spatially heterodyne fringes at a replay angle includes: illuminating a photorefractive crystal having a holographic diffraction grating with a beam from a laser at an illumination angle, the holographic diffraction grating pattern including the spatially heterodyne hologram having spatially heterodyne fringes, wherein a difference between said illumination angle and said replay angle defines a diffraction angle .alpha. that is a function of a plane wave mathematically added to original object wave phase and amplitude data of said spatially heterodyne hologram having spatially heterodyne fringes.

  4. Performance evaluation of a PET detector consisting of an LYSO array coupled to a 4 × 4 array of large-size GAPD for MR compatible imaging

    Science.gov (United States)

    Hong, Key Jo; Choi, Yong; Kang, Jihoon; Hu, Wei; Jung, Jin Ho; Min, Byung Jun; Chung, Yong Hyun; Jackson, Carl

    2011-05-01

    We examined a PET detector consisting of an LYSO array coupled to a 4 × 4 array of large-size Geiger-mode avalanche photodiode (GAPD). The GAPD coupled to 3 mm × 3 mm × 20 mm LYSO pixel crystal has been investigated for possible use as an MR-compatible PET photosensor. Primary characteristics of a PET detector, such as energy resolution and coincidence timing resolution were measured. Gain variation, count uniformity, and count estimation error of 4 × 4 array of LYSO-GAPD were measured to evaluate the performance parameters relevant for PET imaging. The energy resolution and coincidence timing resolution with 511 keV gamma rays were 18.5 ± 0.7% and 1.6 ns, respectively. The gain variation, count uniformity for all 16 channels were 1.3:1 and 1.3:1, respectively. The count estimation error between adjacent channels measured with an LYSO connected to a GAPD pixel was negligible (0.24 ± 0.04%). Long-term stability results show that there was no significant change in the photopeak position, energy resolution and count rate for 20 days. Cable lengths up to 300 cm, used between the GAPD and preamplifier, did not affect photopeak position and energy resolution. The performance of the LYSO-GAPD detector inside the MRI exhibited no significant change compared to that measured outside the MRI. The MR images acquired with and without the operating LYSO-GAPD detector located on top of the RF coil showed no considerable degradation in image quality. These results demonstrate the feasibility of using the LYSO-GAPD detector as PET photosensors, which could be used for MR compatible PET development.

  5. Multi-Channel Deconvolution for Forward-Looking Phase Array Radar Imaging

    Directory of Open Access Journals (Sweden)

    Jie Xia

    2017-07-01

    Full Text Available The cross-range resolution of forward-looking phase array radar (PAR is limited by the effective antenna beamwidth since the azimuth echo is the convolution of antenna pattern and targets’ backscattering coefficients. Therefore, deconvolution algorithms are proposed to improve the imaging resolution under the limited antenna beamwidth. However, as a typical inverse problem, deconvolution is essentially a highly ill-posed problem which is sensitive to noise and cannot ensure a reliable and robust estimation. In this paper, multi-channel deconvolution is proposed for improving the performance of deconvolution, which intends to considerably alleviate the ill-posed problem of single-channel deconvolution. To depict the performance improvement obtained by multi-channel more effectively, evaluation parameters are generalized to characterize the angular spectrum of antenna pattern or singular value distribution of observation matrix, which are conducted to compare different deconvolution systems. Here we present two multi-channel deconvolution algorithms which improve upon the traditional deconvolution algorithms via combining with multi-channel technique. Extensive simulations and experimental results based on real data are presented to verify the effectiveness of the proposed imaging methods.

  6. [Research on the neas infrared focal plane array detector imaging technology used in the laser warning].

    Science.gov (United States)

    Wang, Zhi-Bin; Huang, Yan-Fei; Wang, Yao-Li; Zhang, Rui; Wang, Yan-Chao

    2014-04-01

    In order to achieve the incoming laser's accurate position, it is necessary to improve the detected laser's direction resolution. The InGaAs focal plane array detector with the type of FPA-320 x 256-C was selected as the core component of the diffraction grating laser warning device. The detection theory of laser wavelength and direction based on diffraction grating was introduced. The drive circuit was designed through the analysis of the detector's performance and parameters. Under the FPGA' s timing control, the detector's analog output was sampled by the high-speed AD. The data was cached to FPGA's extended SRAM, and then transferred to a PC through USB. Labview on a PC collects the raw data for processing and displaying. The imaging experiments were completed with the above method. With the wavelength of 1550 nm and 980 nm laser from different directions the diffraction images were detected. Through analysis the location of the zero order and one order can be determined. According to the grating diffraction theory, the wavelength and the direction of the two-dimensional angle can be calculated. It indicates that the wavelength error is less than 10 nm, and the angle error is less than 1 degrees.

  7. Automated image analysis reveals the dynamic 3-dimensional organization of multi-ciliary arrays

    Directory of Open Access Journals (Sweden)

    Domenico F. Galati

    2016-01-01

    Full Text Available Multi-ciliated cells (MCCs use polarized fields of undulating cilia (ciliary array to produce fluid flow that is essential for many biological processes. Cilia are positioned by microtubule scaffolds called basal bodies (BBs that are arranged within a spatially complex 3-dimensional geometry (3D. Here, we develop a robust and automated computational image analysis routine to quantify 3D BB organization in the ciliate, Tetrahymena thermophila. Using this routine, we generate the first morphologically constrained 3D reconstructions of Tetrahymena cells and elucidate rules that govern the kinetics of MCC organization. We demonstrate the interplay between BB duplication and cell size expansion through the cell cycle. In mutant cells, we identify a potential BB surveillance mechanism that balances large gaps in BB spacing by increasing the frequency of closely spaced BBs in other regions of the cell. Finally, by taking advantage of a mutant predisposed to BB disorganization, we locate the spatial domains that are most prone to disorganization by environmental stimuli. Collectively, our analyses reveal the importance of quantitative image analysis to understand the principles that guide the 3D organization of MCCs.

  8. A digital magnetic resonance imaging spectrometer using digital signal processor and field programmable gate array.

    Science.gov (United States)

    Liang, Xiao; Binghe, Sun; Yueping, Ma; Ruyan, Zhao

    2013-05-01

    A digital spectrometer for low-field magnetic resonance imaging is described. A digital signal processor (DSP) is utilized as the pulse programmer on which a pulse sequence is executed as a subroutine. Field programmable gate array (FPGA) devices that are logically mapped into the external addressing space of the DSP work as auxiliary controllers of gradient control, radio frequency (rf) generation, and rf receiving separately. The pulse programmer triggers an event by setting the 32-bit control register of the corresponding FPGA, and then the FPGA automatically carries out the event function according to preset configurations in cooperation with other devices; accordingly, event control of the spectrometer is flexible and efficient. Digital techniques are in widespread use: gradient control is implemented in real-time by a FPGA; rf source is constructed using direct digital synthesis technique, and rf receiver is constructed using digital quadrature detection technique. Well-designed performance is achieved, including 1 μs time resolution of the gradient waveform, 1 μs time resolution of the soft pulse, and 2 MHz signal receiving bandwidth. Both rf synthesis and rf digitalization operate at the same 60 MHz clock, therefore, the frequency range of transmitting and receiving is from DC to ~27 MHz. A majority of pulse sequences have been developed, and the imaging performance of the spectrometer has been validated through a large number of experiments. Furthermore, the spectrometer is also suitable for relaxation measurement in nuclear magnetic resonance field.

  9. Imaging Ionospheric Disturbances with a Global Array of the Ground-Based GPS TEC Receivers

    Science.gov (United States)

    Foster, J. C.; Coster, A.; Rideout, B.; Immel, T.; Rich, F. J.

    2004-05-01

    A prime example of distributed arrays of small instruments for space science research is found in the use of the existing global array of GPS receivers to provide high spatial/temporal resolution mapping of the total electron electron content (TEC) at equatorial, mid, auroral, and polar latitudes. Particularly dramatic effects are observed during major disturbances when magnetospheric electric fields perturb and redistribute the thermal plasmas of inner magnetosphere (plasmasphere/ionosphere). Enhancement and poleward displacement of the equatorial anomalies (EA), the formation of plasmaspheric drainage plumes which erode the outer plasmasphere and produce significant storm enhanced density and space weather effects at mid latitudes, and tongues of ionization which span the polar caps are all a part of the systematic redistribution of the low-latitude thermal plasma during strong events. The present distribution of GPS receivers permits mapping such features primarily over the land masses of North America and Europe, where 1x1 deg spatial and 30-sec temporal observations of vertical TEC can be achieved. Few receivers currently exist in developing countries and large gaps in coverage exist over the oceans. However, the large and meso-scale characteristics and evolution of these thermal plasma storm effects can be identified in the global maps. We address the cross-calibration of ground-based and space-based techniques to image and sample such features by comparing simultaneous observations of the major features observed during the strong storm on May 30, 2003. GPS TEC mapping observed the rapid enhancement of the EA and the formation of a concentration of enhanced plasma in the Carribean sector. This co-rotating enhancement provided a continuing a source for the dusk-sector plasmaspheric drainage plume. The down-looking IMAGE FUV instrument can map enhancements in the equatorial emissions associated with the EA and observed the spatial extent and evolution of the co

  10. Fiber array based hyperspectral Raman imaging for chemical selective analysis of malaria-infected red blood cells

    Energy Technology Data Exchange (ETDEWEB)

    Brückner, Michael [Leibniz Institute of Photonic Technology, 07745 Jena (Germany); Becker, Katja [Justus Liebig University Giessen, Biochemistry and Molecular Biology, 35392 Giessen (Germany); Popp, Jürgen [Leibniz Institute of Photonic Technology, 07745 Jena (Germany); Friedrich Schiller University Jena, Institute for Physical Chemistry, 07745 Jena (Germany); Friedrich Schiller University Jena, Abbe Centre of Photonics, 07745 Jena (Germany); Frosch, Torsten, E-mail: torsten.frosch@uni-jena.de [Leibniz Institute of Photonic Technology, 07745 Jena (Germany); Friedrich Schiller University Jena, Institute for Physical Chemistry, 07745 Jena (Germany); Friedrich Schiller University Jena, Abbe Centre of Photonics, 07745 Jena (Germany)

    2015-09-24

    A new setup for Raman spectroscopic wide-field imaging is presented. It combines the advantages of a fiber array based spectral translator with a tailor-made laser illumination system for high-quality Raman chemical imaging of sensitive biological samples. The Gaussian-like intensity distribution of the illuminating laser beam is shaped by a square-core optical multimode fiber to a top-hat profile with very homogeneous intensity distribution to fulfill the conditions of Koehler. The 30 m long optical fiber and an additional vibrator efficiently destroy the polarization and coherence of the illuminating light. This homogeneous, incoherent illumination is an essential prerequisite for stable quantitative imaging of complex biological samples. The fiber array translates the two-dimensional lateral information of the Raman stray light into separated spectral channels with very high contrast. The Raman image can be correlated with a corresponding white light microscopic image of the sample. The new setup enables simultaneous quantification of all Raman spectra across the whole spatial area with very good spectral resolution and thus outperforms other Raman imaging approaches based on scanning and tunable filters. The unique capabilities of the setup for fast, gentle, sensitive, and selective chemical imaging of biological samples were applied for automated hemozoin analysis. A special algorithm was developed to generate Raman images based on the hemozoin distribution in red blood cells without any influence from other Raman scattering. The new imaging setup in combination with the robust algorithm provides a novel, elegant way for chemical selective analysis of the malaria pigment hemozoin in early ring stages of Plasmodium falciparum infected erythrocytes. - Highlights: • Raman hyperspectral imaging allows for chemical selective analysis of biological samples with spatial heterogeneity. • A homogeneous, incoherent illumination is essential for reliable

  11. Characterization of analytical figures of merit of a sub-diffraction limited fiber bundle array for SERS imaging

    Science.gov (United States)

    Languirand, Eric R.; Cullum, Brian M.

    2016-05-01

    Super resolution chemical imaging can provide high spatial resolution images that contain chemically specific information. Additionally, using a technique such as Raman scattering provides molecular specific information based on the inherent vibrations within the analyte of interest. In this work, commercially available fiber bundle arrays (1mm diameter) consisting of 30,000 individual fiber elements (4μm diameter) that are then modified to obtain surface enhanced Raman scatter are employed. This allows for the visualization of vibrational information with high spatial (i.e. sub-diffraction limited) resolution over the 30,000 individual points of interrogation covering a total imaging diameter of approximately 20μm in a non-scanning format. Using these bundles, it has been shown that dithering can increase the spatial resolution of the arrays further by obtaining several sub-element shifted images. To retain the spatial resolution of such images, cross talk associated with these tpared bundles must be kept at a negligible level. In this paper, a study of luminescent particles isolated in individual fiber wells has been performed to characterize the cross talk associated with these fiber bundles. Scanning-electron microscope (SEM) images provide nanometric characterization of the fiber array, while luminescent signals allow for the quantitation of cross talk between adjacent fiber elements. From these studies negligible cross-talk associated with both untapered and tapered bundles was found to exist.

  12. Intensity correction method customized for multi-animal abdominal MR imaging with 3T clinical scanner and multi-array coil.

    Science.gov (United States)

    Mitsuda, Minoru; Yamaguchi, Masayuki; Nakagami, Ryutaro; Furuta, Toshihiro; Sekine, Norio; Niitsu, Mamoru; Moriyama, Noriyuki; Fujii, Hirofumi

    2013-01-01

    Simultaneous magnetic resonance (MR) imaging of multiple small animals in a single session increases throughput of preclinical imaging experiments. Such imaging using a 3-tesla clinical scanner with multi-array coil requires correction of intensity variation caused by the inhomogeneous sensitivity profile of the coil. We explored a method for correcting intensity that we customized for multi-animal MR imaging, especially abdominal imaging. Our institutional committee for animal experimentation approved the protocol. We acquired high resolution T₁-, T₂-, and T₂*-weighted images and low resolution proton density-weighted images (PDWIs) of 4 rat abdomens simultaneously using a 3T clinical scanner and custom-made multi-array coil. For comparison, we also acquired T₁-, T₂-, and T₂*-weighted volume coil images in the same rats in 4 separate sessions. We used software created in-house to correct intensity variation. We applied thresholding to the PDWIs to produce binary images that displayed only a signal-producing area, calculated multi-array coil sensitivity maps by dividing low-pass filtered PDWIs by low-pass filtered binary images pixel by pixel, and divided uncorrected T₁-, T₂-, or T₂*-weighted images by those maps to obtain intensity-corrected images. We compared tissue contrast among the liver, spinal canal, and muscle between intensity-corrected multi-array coil images and volume coil images. Our intensity correction method performed well for all pulse sequences studied and corrected variation in original multi-array coil images without deteriorating the throughput of animal experiments. Tissue contrasts were comparable between intensity-corrected multi-array coil images and volume coil images. Our intensity correction method customized for multi-animal abdominal MR imaging using a 3T clinical scanner and dedicated multi-array coil could facilitate image interpretation.

  13. Imaging of heart acoustic based on the sub-space methods using a microphone array.

    Science.gov (United States)

    Moghaddasi, Hanie; Almasganj, Farshad; Zoroufian, Arezoo

    2017-07-01

    Heart disease is one of the leading causes of death around the world. Phonocardiogram (PCG) is an important bio-signal which represents the acoustic activity of heart, typically without any spatiotemporal information of the involved acoustic sources. The aim of this study is to analyze the PCG by employing a microphone array by which the heart internal sound sources could be localized, too. In this paper, it is intended to propose a modality by which the locations of the active sources in the heart could also be investigated, during a cardiac cycle. In this way, a microphone array with six microphones is employed as the recording set up to be put on the human chest. In the following, the Group Delay MUSIC algorithm which is a sub-space based localization method is used to estimate the location of the heart sources in different phases of the PCG. We achieved to 0.14cm mean error for the sources of first heart sound (S1) simulator and 0.21cm mean error for the sources of second heart sound (S2) simulator with Group Delay MUSIC algorithm. The acoustical diagrams created for human subjects show distinct patterns in various phases of the cardiac cycles such as the first and second heart sounds. Moreover, the evaluated source locations for the heart valves are matched with the ones that are obtained via the 4-dimensional (4D) echocardiography applied, to a real human case. Imaging of heart acoustic map presents a new outlook to indicate the acoustic properties of cardiovascular system and disorders of valves and thereby, in the future, could be used as a new diagnostic tool. Copyright © 2017. Published by Elsevier B.V.

  14. Flexible integration of high-imaging-resolution and high-power arrays for ultrasound-induced thermal strain imaging (US-TSI).

    Science.gov (United States)

    Stephens, Douglas N; Mahmoud, Ahmed M; Ding, Xuan; Lucero, Steven; Dutta, Debaditya; Yu, Francois T H; Chen, Xucai; Kim, Kang

    2013-12-01

    Ultrasound-induced thermal strain imaging (USTSI) for carotid artery plaque detection requires both high imaging resolution (array design is particularly expensive and inflexible, a new integrated approach is presented which utilizes independent ultrasound arrays to meet the requirements for this particular application. This work demonstrates a new approach in dual-array construction. A 3-D printed manifold was built to support both a high-resolution 20 MHz commercial imaging array and 6 custom heating elements operating in the 3.5 to 4 MHz range. For the application of US-TSI in carotid plaque characterization, the tissue target site is 20 to 30 mm deep, with a typical target volume of 2 mm (elevation) × 8 mm (azimuthal) × 5 mm (depth). The custom heating array performance was fully characterized for two design variants (flat and spherical apertures), and can easily deliver 30 W of total acoustic power to produce intensities greater than 15 W/cm(2) in the tissue target region.

  15. Super-resolution imaging of aquaporin-4 orthogonal arrays of particles in cell membranes.

    Science.gov (United States)

    Rossi, Andrea; Moritz, Tobias J; Ratelade, Julien; Verkman, A S

    2012-09-15

    Aquaporin-4 (AQP4) is a water channel expressed in astrocytes, skeletal muscle and epithelial cells that forms supramolecular aggregates in plasma membranes called orthogonal arrays of particles (OAPs). AQP4 is expressed as a short isoform (M23) that forms large OAPs, and a long isoform (M1) that does not form OAPs by itself but can mingle with M23 to form relatively small OAPs. AQP4 OAPs were imaged with ~20 nm spatial precision by photoactivation localization microscopy (PALM) in cells expressing chimeras of M1- or M23-AQP4 with photoactivatable fluorescent proteins. Native AQP4 was imaged by direct stochastic optical reconstruction microscopy (dSTORM) using a primary anti-AQP4 antibody and fluorescent secondary antibodies. We found that OAP area increased from 1878±747 to 3647±958 nm(2) with decreasing M1:M23 ratio from 1:1 to 1:3, and became elongated. Two-color dSTORM indicated that M1 and M23 co-assemble in OAPs with a M1-enriched periphery surrounding a M23-enriched core. Native AQP4 in astrocytes formed OAPs with an area of 2142±829 nm(2), which increased to 5137±1119 nm(2) with 2-bromopalmitate. PALM of AQP4 OAPs in live cells showed slow diffusion (average ~10(-12) cm(2)/s) and reorganization. OAP area was not altered by anti-AQP4 IgG autoantibodies (NMO-IgG) that cause the neurological disease neuromyelitis optica. Super-resolution imaging allowed elucidation of novel nanoscale structural and dynamic features of OAPs.

  16. 6-Plex microsphere immunoassay with imaging planar array detection for mycotoxins in barley.

    Science.gov (United States)

    Peters, Jeroen; Cardall, Alice; Haasnoot, Willem; Nielen, Michel W F

    2014-08-21

    Mycotoxins are produced by fungi as secondary metabolites. They often multi-contaminate food and feed commodities posing a health risk to humans and animals. A fast and easy to apply multiplex screening of these commodities could be useful to detect multi-contamination. For this, we developed a semi-quantitative 6-plex immunoassay using a suspension array of paramagnetic colour-coded microspheres combined with imaging planar array detection for the mycotoxins aflatoxin B1, ochratoxin A, zearalenone, deoxynivalenol, T2-toxin, HT-2 toxin and fumonisin B1. Mycotoxin specific monoclonal antibodies were coupled to different sets of microspheres and mycotoxins conjugated to the fluorescent protein R-phycoerythrin served as reporter molecules. Competition between free mycotoxins in the sample and mixed reporter molecules for antibody binding sites on mixed microspheres created a multiplex direct inhibition immunoassay. The reagents were selected for no or low cross-interactions between the assays and cross-reactions with metabolites and possible masked forms were determined. A within-laboratory validation was carried out using blank and spiked barley samples. Furthermore, the 6-plex was used to screen available barley, and malted barley, reference materials. The validation showed very high inter and intra-day precision for all samples with a maximum relative standard deviation value of 10%. The screening assay allows easy and rapid multiplex detection of the target mycotoxins in barley according to EU legislation. With a cut off factor of 50%, based on the EU maximum levels, we were able to screen at 2 μg kg(-1) for aflatoxin B1, 2.5 μg kg(-1) for ochratoxin A, 625 μg kg(-1) for deoxynivalenol, 50 μg kg(-1) for zearalenone, 1000 μg kg(-1) for fumonisin B1 and 25 μg kg(-1) for T-2 toxin. Thanks to the transportable planar array system, the developed 6-plex has potential for future on-site testing. Future implementation of this method as a pre-screening tool, prior to

  17. Three-dimensional magnetotelluric imaging of Cascadia subduction zone from an amphibious array

    Science.gov (United States)

    Yang, B.; Egbert, G. D.; Key, K.; Bedrosian, P.; Livelybrooks, D.; Schultz, A.

    2016-12-01

    We present results from three-dimensional inversion of an amphibious magnetotelluric (MT) array consisting of 71 offshore and 75 onshore sites in the central part of Cascadia, to image down-dip and along strike variations of electrical conductivity, and constrain the 3D distribution of fluids and melt in the subduction zone. A larger scale array consisting of EarthScope transportable-array data and several 2D legacy profiles (e.g. EMSLAB, CAFE-MT, SWORMT) which covers WA, OR, northern CA and northern NV has been inverted separately, to provide a broader view of the subduction zone. Inverting these datasets including seafloor data, and involving strong coast effects presents many challenges, especially for the nominal TE mode impedances which have very anomalous phases in both land and seafloor sites. We find that including realistic bathymetry and conductive seafloor sediments significantly stabilizes the inversion, and that a two stage inversion strategy, first emphasizing fit to the more challenging TE data, improved overall data fits. We have also constrained the geometry of the (assumed resistive) subducting plates by extracting morphological parameters (e.g. upper boundary and thickness) from seismological models (McCrory et al 2012, Schmandt and Humphreys 2010). These constraints improve recovery and resolution of subduction related conductivity features. With the strategies mentioned above, we improved overall data fits, resulting in a model which reveals (for the first time) a conductive oceanic asthenosphere, extending under the North America plate. The most striking model features are conductive zones along the plate interface, including a continuous stripe of high conductivity just inboard of the coast, extending from the northern limits of our model in Washington state, to north-central Oregon. High conductivities also occur in patches near the tip of the mantle wedge, at depths appropriate for eclogitization, and at greater depth beneath the arc, in

  18. Sensitivity of an eight-element phased array coil in 3 Tesla MR imaging: a basic analysis.

    Science.gov (United States)

    Hiratsuka, Yoshiyasu; Miki, Hitoshi; Kikuchi, Keiichi; Kiriyama, Ikuko; Mochizuki, Teruhito; Takahashi, Shizue; Sadamoto, Kazuhiko

    2007-01-01

    To evaluate the performance advantages of an 8-element phased array head coil (8 ch coil) over a conventional quadrature-type birdcage head coil (QD coil) with regard to the signal-to-noise ratio (SNR) and image uniformity in 3 Tesla magnetic resonance (MR) imaging. We scanned a phantom filled with silicon oil using an 8 ch coil and a QD coil in a 3T MR imaging system and compared the SNR and image uniformity obtained from T(1)-weighted spin echo (SE) images and T(2)-weighted fast SE images between the 2 coils. We also visually evaluated images from 4 healthy volunteers. The SNR with the 8 ch coil was approximately twice that with the QD coil in the region of interest (ROI), which was set as 75% of the area in the center of the phantom images. With regard to the spatial variation of sensitivity, the SNR with the 8 ch coil was lower at the center of the images than at the periphery, whereas the SNR with the QD coil exhibited an inverse pattern. At the center of the images with the 8 ch coil, the SNR was somewhat lower, and that distribution was relatively flat compared to that in the periphery. Image uniformity varied less with the 8 ch coil than with the QD coil on both imaging sequences. The 8 ch phased array coil was useful for obtaining high quality 3T images because of its higher SNR and improved image uniformity than those obtained with conventional quadrature-type birdcage head coil.

  19. Miniaturized Ultrasound Imaging Probes Enabled by CMUT Arrays with Integrated Frontend Electronic Circuits

    Science.gov (United States)

    Khuri-Yakub, B. (Pierre) T.; Oralkan, Ömer; Nikoozadeh, Amin; Wygant, Ira O.; Zhuang, Steve; Gencel, Mustafa; Choe, Jung Woo; Stephens, Douglas N.; de la Rama, Alan; Chen, Peter; Lin, Feng; Dentinger, Aaron; Wildes, Douglas; Thomenius, Kai; Shivkumar, Kalyanam; Mahajan, Aman; Seo, Chi Hyung; O’Donnell, Matthew; Truong, Uyen; Sahn, David J.

    2010-01-01

    Capacitive micromachined ultrasonic transducer (CMUT) arrays are conveniently integrated with frontend integrated circuits either monolithically or in a hybrid multichip form. This integration helps with reducing the number of active data processing channels for 2D arrays. This approach also preserves the signal integrity for arrays with small elements. Therefore CMUT arrays integrated with electronic circuits are most suitable to implement miniaturized probes required for many intravascular, intracardiac, and endoscopic applications. This paper presents examples of miniaturized CMUT probes utilizing 1D, 2D, and ring arrays with integrated electronics. PMID:21097106

  20. Probabilistic shaping for ROF system with heterodyne coherent detection

    Directory of Open Access Journals (Sweden)

    Bo Liu

    2017-05-01

    Full Text Available We investigate and compare the performance of normal and probabilistic shaping (PS 16-ary quadrature amplitude modulation (16QAM in a photonic vector millimeter-wave (mm-wave signal generation system adopting heterodyne coherent detection. And we obtain a better bit-error ratio (BER performance in the PS 16QAM scheme compared to the normal 16QAM scheme in the simulation. We also for the first time experimentally demonstrate the feasibility of PS-polarization-division-multiplexing 16QAM in a photonic vector mm-wave signal generation system employing heterodyne coherent detection. We obtain the same BER in PS and normal schemes with the PS scheme providing a higher bit rate. Then we experimentally carry out the performance investigation of PS in a 16QAM-modulated radio over fiber system with 40 m wireless transmission.

  1. Piezoelectric dilatometric analysis using homodyne and heterodyne laser interferometry

    Science.gov (United States)

    Delahoussaye, Keith

    The electromechanical coupling of piezoelectric materials has been widely studied since such property is found to be a key element of enhanced sensitivity in piezoelectric sensors or actuators. However a unified view of this coupling as function of frequencies verified using multiple measurement techniques has not previously been available. This study examines and compares multiple optical based homodyne and heterodyne interferometry techniques for piezoelectric displacement measurement, over a wide range of frequencies from DC to 20 MHz. A custom configured homodyne optical interferometer and a commercial heterodyne Laser Doppler Vibrometer are used in the study. Because the frequency ranges used by these devices overlap, it is possible to compare the results. Ferroelectric lead titanate PbTiO3 (PT) ceramic sample with high ferroelectric strain is studied in this work. Frequency dependence of the electromechanical displacement is obtained using multiple techniques and the emphasis of the interrogations is given to frequencies near piezoelectric resonances.

  2. Probabilistic shaping for ROF system with heterodyne coherent detection

    Science.gov (United States)

    Liu, Bo; Li, Xinying; Zhang, Ying; Xin, Xiangjun; Yu, Jianjun

    2017-05-01

    We investigate and compare the performance of normal and probabilistic shaping (PS) 16-ary quadrature amplitude modulation (16QAM) in a photonic vector millimeter-wave (mm-wave) signal generation system adopting heterodyne coherent detection. And we obtain a better bit-error ratio (BER) performance in the PS 16QAM scheme compared to the normal 16QAM scheme in the simulation. We also for the first time experimentally demonstrate the feasibility of PS-polarization-division-multiplexing 16QAM in a photonic vector mm-wave signal generation system employing heterodyne coherent detection. We obtain the same BER in PS and normal schemes with the PS scheme providing a higher bit rate. Then we experimentally carry out the performance investigation of PS in a 16QAM-modulated radio over fiber system with 40 m wireless transmission.

  3. Digital pixel CMOS focal plane array with on-chip multiply accumulate units for low-latency image processing

    Science.gov (United States)

    Little, Jeffrey W.; Tyrrell, Brian M.; D'Onofrio, Richard; Berger, Paul J.; Fernandez-Cull, Christy

    2014-06-01

    A digital pixel CMOS focal plane array has been developed to enable low latency implementations of image processing systems such as centroid trackers, Shack-Hartman wavefront sensors, and Fitts correlation trackers through the use of in-pixel digital signal processing (DSP) and generic parallel pipelined multiply accumulate (MAC) units. Light intensity digitization occurs at the pixel level, enabling in-pixel DSP and noiseless data transfer from the pixel array to the peripheral processing units. The pipelined processing of row and column image data prior to off chip readout reduces the required output bandwidth of the image sensor, thus reducing the latency of computations necessary to implement various image processing systems. Data volume reductions of over 80% lead to sub 10μs latency for completing various tracking and sensor algorithms. This paper details the architecture of the pixel-processing imager (PPI) and presents some initial results from a prototype device fabricated in a standard 65nm CMOS process hybridized to a commercial off-the-shelf short-wave infrared (SWIR) detector array.

  4. Elemental X-ray imaging using the Maia detector array: The benefits and challenges of large solid-angle

    Science.gov (United States)

    Ryan, C. G.; Kirkham, R.; Hough, R. M.; Moorhead, G.; Siddons, D. P.; de Jonge, M. D.; Paterson, D. J.; De Geronimo, G.; Howard, D. L.; Cleverley, J. S.

    2010-07-01

    The fundamental parameter method for quantitative SXRF and PIXE analysis and imaging using the dynamic analysis method is extended to model the changing X-ray yields and detector sensitivity with angle across large detector arrays. The method is implemented in the GeoPIXE software and applied to cope with the large solid-angle of the new Maia 384 detector array and its 96 detector prototype developed by CSIRO and BNL for SXRF imaging applications at the Australian and NSLS synchrotrons. Peak-to-background is controlled by mitigating charge-sharing between detectors through careful optimization of a patterned molybdenum absorber mask. A geological application demonstrates the capability of the method to produce high definition elemental images up to ˜100 M pixels in size.

  5. Spatial-heterodyne spectrometer for transmission-Raman observations.

    Science.gov (United States)

    Foster, M J; Storey, J; Zentile, M A

    2017-01-23

    A new transmission Raman spectrometer has been developed using a spatial heterodyne spectrometer (SHS), taking advantage of the high etendue inherent in this class of spectrometer to maximize the light collected from the target. The system has been tested against paracetamol tablet samples. The instrument has been shown to accept light from 0.05 mm up to a 3 mm core diameter fibre bundle with a numerical aperture of 0.22, whilst no degradation in resolution is observed.

  6. Molecular Spectroscopy With a Compact 557-GHz Heterodyne Receiver

    OpenAIRE

    Neumaier, Philipp F.-X.; Richter, Heiko; Stake, Jan; Zhao, Huan; Tang, Aik-Yean; Drakinskiy, Vladimir; Sobis, Peter; Emrich, Anders; Hülsmann, Axel; Johansen, Tom K.; Bryllert, Tomas; Hanning, Johanna; Krozer, Viktor; Hübers, Heinz-Wilhelm

    2014-01-01

    We report on a heterodyne terahertz spectrometer based on a fully integrated 557-GHz receiver and a digital fast Fourier transform spectrometer. The receiver consists of a chain of multipliers and power amplifiers, followed by a heterostructure barrier varactor tripler that subharmonically pumps a membrane GaAs Schottky diode mixer. All sub-components are newly developed and optimized with regard to the overall receiver performance such as noise temperature, power consumption, weight and phys...

  7. Smart-phone based computational microscopy using multi-frame contact imaging on a fiber-optic array

    OpenAIRE

    Navruz, Isa; Coskun, Ahmet F.; Wong, Justin; Mohammad, Saqib; Tseng, Derek; Nagi, Richie; Phillips, Stephen; Ozcan, Aydogan

    2013-01-01

    We demonstrate a cellphone based contact microscopy platform, termed Contact Scope, which can image highly dense or connected samples in transmission mode. Weighing approximately 76 grams, this portable and compact microscope is installed on the existing camera unit of a cellphone using an opto-mechanical add-on, where planar samples of interest are placed in contact with the top facet of a tapered fiber-optic array. This glass-based tapered fiber array has ∼9 fold higher density of fiber opt...

  8. Scintillating Fiber Array Characterization and Alignment for Neutron Imaging using the High Energy X-ray (HEX) Facility

    Energy Technology Data Exchange (ETDEWEB)

    Buckles, R. A., Ali, Z. A., Cradick, J. R., Traille, A. J., Warthan, W. A.

    2009-09-04

    The Neutron Imager diagnostic at the National Ignition Facility (NIF) located at Lawrence Livermore National Laboratory (LLNL) will produce high-resolution, gated images of neutron-generating implosions. A similar pinhole imaging experiment (PINEX) diagnostic was recently deployed at the Z facility at Sandia National Laboratories (SNL). Both the SNL and LLNL neutron imagers use similar fiber array scintillators (BCF-99-555). Despite diverse resolution and magnification requirements, both diagnostics put significant onus on the scintillator spatial quality and alignment precision to maintain optimal point spread. Characterization and alignment of the Z-PINEX scintillator and imaging system were done at NSTec/Livermore Operations in 2009, and is currently underway for the NIF Neutron Imager.

  9. Heterodyne QELS instrument for diagnostics of biological fluids

    Science.gov (United States)

    Lebedev, Andrei D.; Ivanova, Mariya A.; Lomakin, Aleksey V.; Noskin, Valentin A.

    1997-05-01

    The instrument for the quasielastic light scattering (QELS), LCS-03 utilizes heterodyne optical scheme which permits a high resolution determination of particle size distribution. The vibration related problems, which are common for the heterodyne techniques, have been overcome by using a single glass block incorporating all the optical elements. The real-time correlation analysis of the photocurrent fluctuations is performed by a PC-embedded analog-to-digit converter card with digital signal processor (DSP) using an original algorithm. Both the technical specifications of the instrument and the software for the size distribution analysis are presented. The heterodyne technique consistently outperforms the homodyne one when the accurate characterization of the particle size distributions in heterogeneous systems is required. Diagnostic analysis of size distribution of particles in blood serum/plasma, liquor and saliva is such an application. This kind of diagnostics usually requires a simultaneous analysis of huge number of QELS data. The original statistical algorithm with graphic user interface is described. We discuss the technical specifications of instrumentation as well as methodical problems of biological fluids QELS diagnostics.

  10. Infrared Heterodyne Spectroscopy and its Unique Application to Planetary Studies

    Science.gov (United States)

    Kostiuk, Theodore

    2009-01-01

    Since the early 1970's the infrared heterodyne technique has evolved into a powerful tool for the study of molecular constituents, temperatures, and dynamics in planetary atmospheres. Its extremely high spectral resolution (Lambda/(Delta)Lambda/>10(exp 6)) and highly accurate frequency measurement (to 1 part in 10(exp 8)) enabled the detection of nonthermal/natural lasing phenomena on Mars and Venus; direct measurements of winds on Venus, Mars, and Titan; study of mid-infrared aurorae on Jupiter; direct measurement of species abundances on Mars (ozone, isotopic CO2), hydrocarbons on Jupiter, Saturn., Neptune, and Titan, and stratospheric composition in the Earth's stratosphere (O3, CIO, N2O, CO2 ....). Fully resolved emission and absorption line shapes measured by this method enabled the unambiguous retrieval of molecular abundances and local temperatures and thermal structure in regions not probed by other techniques. The mesosphere of Mars and thermosphere of Venus are uniquely probed by infrared heterodyne spectroscopy. Results of these studies tested and constrained photochemical and dynamical theoretical models describing the phenomena measured. The infrared heterodyne technique will be described. Highlights in its evolution to today's instrumentation and resultant discoveries will be presented, including work at Goddard Space Flight Center and the University of Koln. Resultant work will include studies supporting NASA and ESA space missions and collaborations between instrumental and theoretical groups.

  11. Design and implementation of Gm-APD array readout integrated circuit for infrared 3D imaging

    Science.gov (United States)

    Zheng, Li-xia; Yang, Jun-hao; Liu, Zhao; Dong, Huai-peng; Wu, Jin; Sun, Wei-feng

    2013-09-01

    A single-photon detecting array of readout integrated circuit (ROIC) capable of infrared 3D imaging by photon detection and time-of-flight measurement is presented in this paper. The InGaAs avalanche photon diodes (APD) dynamic biased under Geiger operation mode by gate controlled active quenching circuit (AQC) are used here. The time-of-flight is accurately measured by a high accurate time-to-digital converter (TDC) integrated in the ROIC. For 3D imaging, frame rate controlling technique is utilized to the pixel's detection, so that the APD related to each pixel should be controlled by individual AQC to sense and quench the avalanche current, providing a digital CMOS-compatible voltage pulse. After each first sense, the detector is reset to wait for next frame operation. We employ counters of a two-segmental coarse-fine architecture, where the coarse conversion is achieved by a 10-bit pseudo-random linear feedback shift register (LFSR) in each pixel and a 3-bit fine conversion is realized by a ring delay line shared by all pixels. The reference clock driving the LFSR counter can be generated within the ring delay line Oscillator or provided by an external clock source. The circuit is designed and implemented by CSMC 0.5μm standard CMOS technology and the total chip area is around 2mm×2mm for 8×8 format ROIC with 150μm pixel pitch. The simulation results indicate that the relative time resolution of the proposed ROIC can achieve less than 1ns, and the preliminary test results show that the circuit function is correct.

  12. Tracking serum antibody response to viral antigens with arrayed imaging reflectometry

    Science.gov (United States)

    Mace, Charles R.; Rose, Robert C.; Miller, Benjamin L.

    2009-02-01

    Arrayed Imaging Reflectometry, or "AIR", is a new label-free technique for detecting proteins that relies on bindinginduced changes in the response of an antireflective coating on the surface of a silicon ship. Because the technique provides high sensitivity, excellent dynamic range, and readily integrates with standard silicon wafer processing technology, it is an exceptionally attractive platform on which to build systems for detecting proteins in complex solutions. In our early research, we used AIR chips bearing secreted receptor proteins from enteropathogenic E. coli to develop sensors for this pathogen. Recently, we have been exploring an alternative strategy: Rather than detecting the pathogen directly, can one immobilize antigens from a pathogen, and employ AIR to detect antibody responses to those antigens? Such a strategy would provide enhanced sensitivity for pathogen detection (as the immune system essentially amplifies the "signal" caused by the presence of an organism to which it responds), and would also potentially prove useful in the process of vaccine development. We describe herein preliminary results in the application of such a strategy to the detection of antibodies to human papillomavirus (HPV).

  13. Ultra-fast processing of gigapixel Tissue MicroArray images using high performance computing.

    Science.gov (United States)

    Wang, Yinhai; McCleary, David; Wang, Ching-Wei; Kelly, Paul; James, Jackie; Fennell, Dean A; Hamilton, Peter W

    2011-10-01

    Tissue MicroArrays (TMAs) are a valuable platform for tissue based translational research and the discovery of tissue biomarkers. The digitised TMA slides or TMA Virtual Slides, are ultra-large digital images, and can contain several hundred samples. The processing of such slides is time-consuming, bottlenecking a potentially high throughput platform. A High Performance Computing (HPC) platform for the rapid analysis of TMA virtual slides is presented in this study. Using an HP high performance cluster and a centralised dynamic load balancing approach, the simultaneous analysis of multiple tissue-cores were established. This was evaluated on Non-Small Cell Lung Cancer TMAs for complex analysis of tissue pattern and immunohistochemical positivity. The automated processing of a single TMA virtual slide containing 230 patient samples can be significantly speeded up by a factor of circa 22, bringing the analysis time to one minute. Over 90 TMAs could also be analysed simultaneously, speeding up multiplex biomarker experiments enormously. The methodologies developed in this paper provide for the first time a genuine high throughput analysis platform for TMA biomarker discovery that will significantly enhance the reliability and speed for biomarker research. This will have widespread implications in translational tissue based research.

  14. Terahertz Real-Time Imaging Uncooled Arrays Based on Antenna-Coupled Bolometers or FET Developed at CEA-Leti

    Science.gov (United States)

    Simoens, François; Meilhan, Jérôme; Nicolas, Jean-Alain

    2015-10-01

    Sensitive and large-format terahertz focal plane arrays (FPAs) integrated in compact and hand-held cameras that deliver real-time terahertz (THz) imaging are required for many application fields, such as non-destructive testing (NDT), security, quality control of food, and agricultural products industry. Two technologies of uncooled THz arrays that are being studied at CEA-Leti, i.e., bolometer and complementary metal oxide semiconductor (CMOS) field effect transistors (FET), are able to meet these requirements. This paper reminds the followed technological approaches and focuses on the latest modeling and performance analysis. The capabilities of application of these arrays to NDT and security are then demonstrated with experimental tests. In particular, high technological maturity of the THz bolometer camera is illustrated with fast scanning of large field of view of opaque scenes achieved in a complete body scanner prototype.

  15. 3D ultrasound imaging performance of a row-column addressed 2D array transducer: a simulation study

    DEFF Research Database (Denmark)

    Rasmussen, Morten Fischer; Jensen, Jørgen Arendt

    2013-01-01

    This paper compares the imaging performance of a 128+128 element row-column addressed array with a fully addressed 1616 2D array. The comparison is made via simulations of the point spread function with Field II. Both arrays have lambda-pitch, a center frequency of 3:5MHz and use 256 active...... echoes are shown to be suppressed when the sub-elements within each of the emulated row and column elements are apodized. The maximum ghost intensity is suppressed by 22:2 dB compared to using no apodization. With apodization applied, the full-width-at-half-maximum in the lateral direction for the fully...

  16. Fast, high-resolution surface potential measurements in air with heterodyne Kelvin probe force microscopy

    Science.gov (United States)

    Garrett, Joseph L.; Munday, Jeremy N.

    2016-06-01

    Kelvin probe force microscopy (KPFM) adapts an atomic force microscope to measure electric potential on surfaces at nanometer length scales. Here we demonstrate that Heterodyne-KPFM enables scan rates of several frames per minute in air, and concurrently maintains spatial resolution and voltage sensitivity comparable to frequency-modulation KPFM, the current spatial resolution standard. Two common classes of topography-coupled artifacts are shown to be avoidable with H-KPFM. A second implementation of H-KPFM is also introduced, in which the voltage signal is amplified by the first cantilever resonance for enhanced sensitivity. The enhanced temporal resolution of H-KPFM can enable the imaging of many dynamic processes, such as such as electrochromic switching, phase transitions, and device degredation (battery, solar, etc), which take place over seconds to minutes and involve changes in electric potential at nanometer lengths.

  17. Ultrafast chirped optical waveform recording using referenced heterodyning and a time microscope

    Science.gov (United States)

    Bennett, Corey Vincent

    2010-06-15

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. This invention expands upon previous work in temporal imaging by adding heterodyning, which can be self-referenced for improved precision and stability, to convert frequency chirp (the second derivative of phase with respect to time) into a time varying intensity modulation. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  18. Ultrafast chirped optical waveform recorder using referenced heterodyning and a time microscope

    Science.gov (United States)

    Bennett, Corey Vincent [Livermore, CA

    2011-11-22

    A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. This invention expands upon previous work in temporal imaging by adding heterodyning, which can be self-referenced for improved precision and stability, to convert frequency chirp (the second derivative of phase with respect to time) into a time varying intensity modulation. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.

  19. Characterization of the impact to PET quantification and image quality of an anterior array surface coil for PET/MR imaging.

    Science.gov (United States)

    Wollenweber, Scott D; Delso, Gaspar; Deller, Timothy; Goldhaber, David; Hüllner, Martin; Veit-Haibach, Patrick

    2014-04-01

    The aim of this study was to determine the impact to PET quantification, image quality and possible diagnostic impact of an anterior surface array used in a combined PET/MR imaging system. An extended oval phantom and 15 whole-body FDG PET/CT subjects were re-imaged for one bed position following placement of an anterior array coil at a clinically realistic position. The CT scan, used for PET attenuation correction, did not include the coil. Comparison, including liver SUV(mean), was performed between the coil present and absent images using two methods of PET reconstruction. Due to the time delay between PET scans, a model was used to account for average physiologic time change of SUV. On phantom data, neglecting the coil caused a mean bias of -8.2% for non-TOF/PSF reconstruction, and -7.3% with TOF/PSF. On clinical data, the liver SUV neglecting the coil presence fell by -6.1% (± 6.5%) for non-TOF/PSF reconstruction; respectively -5.2% (± 5.3%) with TOF/PSF. All FDG-avid features seen with TOF/PSF were also seen with non-TOF/PSF reconstruction. Neglecting coil attenuation for this anterior array coil results in a small but significant reduction in liver SUV(mean) but was not found to change the clinical interpretation of the PET images.

  20. A field-programmable gate array based system for high frame rate laser Doppler blood flow imaging.

    Science.gov (United States)

    Nguyen, H C; Hayes-Gill, B R; Morgan, S P; Zhu, Y; Boggett, D; Huang, X; Potter, M

    2010-01-01

    This paper presents a general embedded processing system implemented in a field-programmable gate array providing high frame rate and high accuracy for a laser Doppler blood flow imaging system. The proposed system can achieve a basic frame rate of flow images at 1 frame/second for 256 x 256 images with 1024 fast Fourier transform (FFT) points used in the processing algorithm. Mixed fixed-floating point calculations are utilized to achieve high accuracy but with a reasonable resource usage. The implementation has a root mean square deviation of the relative difference in flow values below 0.1% when compared with a double-precision floating point implementation. The system can contain from one or more processing units to obtain the required frame rate and accuracy. The performance of the system is significantly higher than other methods reported to date. Furthermore, a dedicated field-programmable gate array (FPGA) board has been designed to test the proposed processing system. The board is linked with a laser line scanning system, which uses a 64 x 1 photodetector array. Test results with various operating parameters show that the performance of the new system is better, in terms of noise and imaging speed, than has been previously achieved.

  1. On an adaptive scene-based gray super-resolution technique of infrared focal plane array imaging system

    Science.gov (United States)

    He, Ming; Zhang, Tian-yi; Liu, Wei-xin; Zhang, Cheng-bin; Zhang, Jin-hao

    2013-09-01

    When infrared focal plane array imaging system detects targets, especially small targets, there is the problem of low gray resolution. In this paper, an adaptive scene-based gray super-resolution technique is proposed, aiming to solve the problem. The paper gives a detailed description on the method of image gray super-resolution by adjusting the signal sample range in infrared focal plane array (IRFPA) imaging system. The method contains the following three parts: extracting the effective gray range from the scene, and obtaining the basis of super-resolution adjustment; providing the adjusting parameters after filter-predicting the basis of adjustment, combining with the adaptive LMS-based filtering algorithm; and completing gray super-resolution by controlling the parameters in super-resolution circuit. Finally, the total solution is experiment validated. The experiment in infrared focal plane array imaging system has proven the feasibility and effectiveness of this method, and the improvement of super-resolution. Then test set shows the MRTD can be increased more than one time.

  2. High-resolution imaging of remanent state and magnetization reversal of superdomain structures in high-density cobalt antidot arrays.

    Science.gov (United States)

    Rodríguez, L A; Magén, C; Snoeck, E; Gatel, C; Castán-Guerrero, C; Sesé, J; García, L M; Herrero-Albillos, J; Bartolomé, J; Bartolomé, F; Ibarra, M R

    2014-09-26

    Remanent state and magnetization reversal processes of a series of cobalt antidot arrays with a fixed hole diameter (d ≈ 55 nm) and an array periodicity (p) ranging between 95 and 524 nm were studied by in situ Lorentz microscopy (LM) as a function of the magnetic field. At remanence, defocused LM images showed the periodicity dependence of the magnetic states inside the lattice. A remarkable transition was observed in the type of domain structures as a function of p: for the large periodicities (p > 300 nm), conventional 90° and 180° domain walls were formed, whereas in small-period antidot arrays (p ≦ 160 nm) magnetic superdomain walls (SDWs) were nucleated to separate regions with different average magnetization direction, the so-called magnetic superdomains. In the SDW regime, a low-frequency Fourier filtering method was implemented to allow a quantitative analysis of the LM images by the transport of intensity equation method. In situ LM experiments under applied magnetic fields were performed to study the reversal magnetization process in a particular array (p = 160 nm), and clear differences were observed as a function of the magnetic field orientation. The switching process under magnetic fields parallel to the horizontal antidot rows occurs in two stages: the system first nucleates and propagates horizontal SDWs, parallel to the field. Then, at higher magnetic fields, vertical SDWs, perpendicular to the field, appear before saturation. When the magnetic field is applied at 45° with respect to the antidot rows, both horizontal and vertical SDWs are nucleated and propagated simultaneously. All the experiments were successfully correlated with micromagnetic simulations. The current study sheds new light on the magnetization reversal processes of antidot arrays and opens new possibilities of exploiting the potential of high-resolution in situ LM and new data analysis procedures to probe magnetization processes in nanomagnetism, particularly in

  3. Cryogenic phased-array for high resolution magnetic resonance imaging (MRI); assessment of clinical and research applications

    Science.gov (United States)

    Ip, Flora S.

    Magnetic Resonance (MR) imaging is one of the most powerful tools in diagnostic medicine for soft tissue imaging. Image acquisition techniques and hardware receivers are very important in achieving high contrast and high resolution MR images. An aim of this dissertation is to design single and multi-element room and cryogenic temperature arrays and make assessments of their signal-to-noise ratio (SNR) and SNR gain. In this dissertation, four sets of MR receiver coils are built. They are the receiver-only cryo-coils that are not commercially available. A tuning and matching circuit is attached to each coil. The tuning and matching circuits are simple; however, each device component has to operate at a high magnetic field and cryogenic temperature environment. Remote DC bias of the varactor controls the tuning and matching outside the scanner room. Active detuning of the resonator is done by two p-i-n junction (PIN) diodes. Cooling of the receiver is done by a customized liquid nitrogen cryostat. The first application is to build a 3-Tesla 2x1 horseshoe counter-rotating current (CRC) cryogenic array to image the tibia in a human body. With significant increase in SNR, the surface coil should deliver high contrast and resolution images that can show the trabecular bone and bone marrow structure. This structural image will be used to model the mechanical strength of the bone as well as bone density and chance of fracture. The planar CRC is a unique design of this surface array. The second application is to modify the coil design to 7-Tesla to study the growth of infant rhesus monkey eyes. Fast scan MR images of the infant monkey heads are taken for monitoring shapes of their eyeballs. The monkeys are induced with shortsightedness by eye lenses, and they are scanned periodically to get images of their eyeballs. The field-of-view (FOV) of these images is about five centimeters and the area of interest is two centimeters deep from the surface. Because of these reasons

  4. Advanced 3-D Ultrasound Imaging: 3-D Synthetic Aperture Imaging using Fully Addressed and Row-Column Addressed 2-D Transducer Arrays

    DEFF Research Database (Denmark)

    Bouzari, Hamed

    because synthetic aperture imaging removes the limitation of a fixed transmit focal depth and instead enables dynamic transmit focusing. Particularly, synthetic aperture imaging could increase the achievable volume rate compared with parallel beamforming, to almost 50 times. Lately, the major ultrasound...... companies have produced ultrasound scanners using 2-D transducer arrays with enough transducer elements to produce high quality 3-D images. Because of the large matrix transducers with integrated custom electronics, these systems are extremely expensive. The relatively low price of ultrasound scanners...

  5. Core-shell diode array for high performance particle detectors and imaging sensors: status of the development

    Science.gov (United States)

    Jia, G.; Hübner, U.; Dellith, J.; Dellith, A.; Stolz, R.; Plentz, J.; Andrä, G.

    2017-02-01

    We propose a novel high performance radiation detector and imaging sensor by a ground-breaking core-shell diode array design. This novel core-shell diode array are expected to have superior performance respect to ultrahigh radiation hardness, high sensitivity, low power consumption, fast signal response and high spatial resolution simultaneously. These properties are highly desired in fundamental research such as high energy physics (HEP) at CERN, astronomy and future x-ray based protein crystallography at x-ray free electron laser (XFEL) etc.. This kind of detectors will provide solutions for these fundamental research fields currently limited by instrumentations. In this work, we report our progress on the development of core-shell diode array for the applications as high performance imaging sensors and particle detectors. We mainly present our results in the preparation of high aspect ratio regular silicon rods by metal assisted wet chemical etching technique. Nearly 200 μm deep and 2 μm width channels with high aspect ratio have been etched into silicon. This result will open many applications not only for the core-shell diode array, but also for a high density integration of 3D microelectronics devices.

  6. Fabrication of Prototype of Artificial Retina Adapted to a Curved Image Plane Based on Arrayed PMMA Microfibers

    Directory of Open Access Journals (Sweden)

    Jian Hong Chen

    2011-05-01

    Full Text Available The traditional visual prosthesis combines both a camera and an electrode array implanted on the visual neural networks. Here, we introduce a new design of artificial retina which integrate the transmission of image and the electrical stimulation of cortical neurons on a single PMMA micro fiber. It is comprised of multiple PMMA microfibers with both ends connected with one flexible and one rigid substrates. The flexible one is a PDMS mold of microrods and ready to conform to a curved image plane. The rigid one is in the form of a silica plate coated with a PMMA thin film and could be attached to a CMOS image sensor for the evaluation of its optical performance. The multiple PMMA microfibers were directly drawn from liquid PMMA thin film with PDMS rods. With arrayed PMMA microfibers, the image planes could be transferred from the flexible to rigid substrate. Each PMMA microfiber delivers a part of the image the PDMS mold transmits. Incorporated with O/E convertors, each micro fiber could function as an unit of electrical stimulation in accordance with part of the image the artificial retina delivered and is ready to function as a cortical neural prosthesis in the future application.

  7. Design and analysis of an ultrasonic transducer micro-array for near-field imaging of age related macular degeneration

    Science.gov (United States)

    Clarke, Clyde C.

    Obtaining quantitative data about tissue has been a goal of ultrasonography since its inception, such data provides invaluable information for diagnosing disease. Traditional ultrasound imaging techniques (B-Mode, C-Mode and M-Mode) have been used to diagnose diseases from images of organs. However, images obtained via these techniques, in some cases, provide limited information about the pathology of the tissues being examined. This is because much of the information that is used for diagnosis depends upon qualitative cues emerging from the echoic profiles of bulk tissue properties. In order to obtain quantitative information about tissue properties, an understanding of the interaction of the ultrasound system proper and tissue is necessary. This requires the creation of detailed models of both the ultrasound imaging system and tissue. These models enable us to obtain quantitative information about tissue, by examining features of backscattered data, generated by the interaction of the ultrasonic imaging system with the tissue under examination. Imaging systems are typically designed with little consideration of the constraints of the imaging environment or the acoustic features of the tissue which include impedance, scatterer size, shape and density. We propose to take into account the physical properties of tissue in designing ultrasonic imaging arrays. We develop a framework for designing ultrasonic imaging systems (primarily the transducer and transducer array) with physical parameters that are tuned to detect specific features of tissue. The design methodology obtains the parameters of an NxN transducer array constrained to a size of e.g. 2mm x 2mm (the size required for medical imaging). The physical parameters of the transducer elements are also obtained for capacitive micromachined ultrasonic transducer (cMUT) technology. In addition to the overall size constraints (2 mm x 2 mm), several other constraints put limitation upon the possible system

  8. Spatial Heterodyne Imager for Mesospheric Radicals on STPSat-1

    Science.gov (United States)

    2010-10-22

    the door, which was comprised of blackened knife edges to minimize scattered light. 4.1.2. Passband Filter [20] An interference filter was located in...the camera housing by a solid copper heat pipe. Before launch, the evacuation port of the housing was replaced by a light tight, sintered metal disk

  9. 320x240 pixel InGaAs/InP focal plane array for short-wave infrared and visible light imaging

    Science.gov (United States)

    Martin, Tara; Dixon, Peter; Gagliardi, Mari-Anne; Masaun, Navneet

    2005-04-01

    We report on the recent production release of our 320x240 pixel InGaAs/InP focal plane array and camera for visible and short-wavelength infrared light imaging. For this camera, we have fabricated a substrate-removed backside-illuminated InGaAs/InP photodiode array hybridized to a silicon read out integrated circuit (ROIC). Removing the InP substrate from the focal plane array allows visible wavelengths, which would otherwise be absorbed by the InP substrate due to its 920 nm wavelength cut-off, to reach the pixels" active region. Quantum efficiency is approximately 15% at 500 nm, 70% at 850 nm, 85% at 1310 nm and 80% at 1550 nm. This focal plane array is useable for visible imaging as well as imaging eye-safe lasers and is of particular interest for day and low light level imaging as well as hyperspectral imaging.

  10. Linear terrestrial laser scanning using array avalanche photodiodes as detectors for rapid three-dimensional imaging.

    Science.gov (United States)

    Cai, Yinqiao; Tong, Xiaohua; Tong, Peng; Bu, Hongyi; Shu, Rong

    2010-12-01

    As an active remote sensor technology, the terrestrial laser scanner is widely used for direct generation of a three-dimensional (3D) image of an object in the fields of geodesy, surveying, and photogrammetry. In this article, a new laser scanner using array avalanche photodiodes, as designed by the Shanghai Institute of Technical Physics of the Chinese Academy of Sciences, is introduced for rapid collection of 3D data. The system structure of the new laser scanner is first presented, and a mathematical model is further derived to transform the original data to the 3D coordinates of the object in a user-defined coordinate system. The performance of the new laser scanner is tested through a comprehensive experiment. The result shows that the new laser scanner can scan a scene with a field view of 30° × 30° in 0.2 s and that, with respect to the point clouds obtained on the wall and ground floor surfaces, the root mean square errors for fitting the two planes are 0.21 and 0.01 cm, respectively. The primary advantages of the developed laser scanner include: (i) with a line scanning mode, the new scanner achieves simultaneously the 3D coordinates of 24 points per single laser pulse, which enables it to scan faster than traditional scanners with a point scanning mode and (ii) the new scanner makes use of two galvanometric mirrors to deflect the laser beam in both the horizontal and the vertical directions. This capability makes the instrument smaller and lighter, which is more acceptable for users.

  11. 3-D Imaging using Row–Column-Addressed 2-D Arrays with a Diverging Lens: Phantom Study

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Engholm, Mathias; Beers, Christopher

    2017-01-01

    A double-curved diverging lens over a flat row– column-addressed (RCA) 2-D array can extend its inherent rectilinear 3-D imaging field-of-view (FOV) to a curvilinear volume region, which is necessary for applications such as abdominal and cardiac imaging. A concave lens with radius of 12.7 mm...... was manufactured using RTV664 silicone. The diverging properties of the lens were evaluated based on measurements on several phantoms. The measured 6 dB FOV in contact with a material similar to human soft tissue was less than 15% different from the theoretical predictions, i.e., a curvilinear FOV of 32...

  12. Enhanced depth-of-field of an integral imaging microscope using a bifocal holographic optical element-micro lens array.

    Science.gov (United States)

    Kwon, Ki-Chul; Lim, Young-Tae; Shin, Chang-Won; Erdenebat, Munkh-Uchral; Hwang, Jae-Moon; Kim, Nam

    2017-08-15

    We propose and implement an integral imaging microscope with extended depth-of-field (DoF) using a bifocal holographic micro lens array (MLA). The properties of the two MLAs are switched via peristrophic multiplexing, where different properties of the MLA are recorded onto the single holographic optical element (HOE). The recorded MLA properties are perpendicular to each other: after the first mode is recorded, the HOE is rotated by 90° clockwise, and the second mode is recorded. The experimental results confirm that the DoF of the integral imaging microscopy system is extended successfully by using the bifocal MLA.

  13. Efficient Array Design for Sonotherapy

    OpenAIRE

    Stephens, Douglas N.; Kruse, Dustin E.; Ergun, Arif S.; Barnes, Stephen; Ming Lu, X.; Ferrara, Katherine

    2008-01-01

    New linear multi-row, multi-frequency arrays have been designed, constructed and tested as fully operational ultrasound probes to produce confocal imaging and therapeutic acoustic intensities with a standard commercial ultrasound imaging system. The triple-array probes and imaging system produce high quality B-mode images with a center row imaging array at 5.3 MHz, and sufficient acoustic power with dual therapeutic arrays to produce mild hyperthermia at 1.54 MHz. The therapeutic array pair i...

  14. Heterodyne pump probe measurements of nonlinear dynamics in an indium phosphide photonic crystal cavity

    DEFF Research Database (Denmark)

    Heuck, Mikkel; Combrié, S.; Lehoucq, G.

    2013-01-01

    Using a sensitive two-color heterodyne pump-probe technique, we investigate the carrier dynamics of an InP photonic crystal nanocavity. The heterodyne technique provides unambiguous results for all wavelength configurations, including the degenerate case, which cannot be investigated with the wid...

  15. The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)

    NARCIS (Netherlands)

    Graauw, T. de; Helmich, F.P.; Phillips, T.G.; Stutzki, J.; Caux, E.; Whyborn, N.D.; Dieleman, P.; Roelfsema, P.R.; Aarts, H.; Assendorp, R.; Bachiller, R.; Baechtold, W.; Barcia, A.; Beintema, D.A.; Belitsky, V.; Benz, A.O.; Bieber, R.; Boogert, A.; Borys, C.; Bumble, B.; Caïs, P.; Caris, M.; Cerulli-Irelli, P.; Chattopadhyay, G.; Cherednichenko, S.; Ciechanowicz, M.; Coeur-Joly, O.; Comito, C.; Cros, A.; Jonge, A. de; Lange, G. de; Delforges, B.; Delorme, Y.; Boggende, T. den; Desbat, J.M.; Diez-González, C.; Di Giorgio, A.M.; Dubbeldam, L.; Edwards, K.; Eggens, M.; Erickson, N.; Evers, J.; Fich, M.; Finn, T.; Franke, B.; Gaier, T.; Gal, C.; Gao, J.R.; Gallego, J.D.; Gauffre, S.; Gill, J.J.; Glenz, S.; Golstein, H.; Goulooze, H.; Gunsing, T.; Güsten, R.; Hartogh, P.; Hatch, W.A.; Higgins, R.; Honingh, E.C.; Huisman, R.; Jackson, B.D.; Jacobs, H.; Jacobs, K.; Jarchow, C.; Javadi, H.; Jellema, W.; Justen, M.; Karpov, A.; Kasemann, C.; Kawamura, J.; Keizer, G.; Kester, D.; Klapwijk, T.M.; Klein, T.; Kollberg, E.; Kooi, J.; Kooiman, P.P.; Kopf, B.; Krause, M.; Krieg, J.M.; Kramer, C.; Kruizenga, B.; Kuhn, T.; Laauwen, W.; Lai, R.; Larsson, B.; Leduc, H.G.; Leinz, C.; Lin, R.H.; Liseau, R.; Liu, G.S.; Loose, A.; López-Fernandez, I.; Lord, S.; Luinge, W.; Marston, A.; Martín-Pintado, J.; Maestrini, A.; Maiwald, F.W.; McCoey, C.; Mehdi, I.; Megej, A.; Melchior, M.; Meinsma, L.; Merkel, H.; Michalska, M.; Monstein, C.; Moratschke, D.; Morris, P.; Muller, H.; Murphy, J.A.; Naber, A.; Natale, E.; Nowosielski, W.; Nuzzolo, F.; Olberg, M.; Olbrich, M.; Orfei, R.; Orleanski, P.; Ossenkopf, V.; Peacock, T.; Pearson, J.C.; Peron, I.; Phillip-May, S.; Piazzo, L.; Planesas, P.; Rataj, M.; Ravera, L.; Risacher, C.; Salez, M.; Samoska, L.A.; Saraceno, P.; Schieder, R.; Schlecht, E.; Schlöder, F.; Schmülling, F.; Schultz, M.; Schuster, K.; Siebertz, O.; Smit, H.; Szczerba, R.; Shipman, R.; Steinmetz, E.; Stern, J.A.; Stokroos, M.; Teipen, R.; Teyssier, D.; Tils, T.; Trappe, N.; Baaren, C. van; Leeuwen, B.J. van; Stadt, H. van de; Visser, H.; Wildeman, K.J.; Wafelbakker, C.K.; Ward, J.S.; Wesselius, P.; Wild, W.; Wulff, S.; Wunsch, H.J.; Tielens, X.; Zaal, P.; Zirath, H.; Zmuidzinas, J.; Zwart, F.

    2010-01-01

    Aims. This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods. The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the

  16. A Novel 3D Imaging Method for Airborne Downward-Looking Sparse Array SAR Based on Special Squint Model

    Directory of Open Access Journals (Sweden)

    Xiaozhen Ren

    2014-01-01

    Full Text Available Three-dimensional (3D imaging technology based on antenna array is one of the most important 3D synthetic aperture radar (SAR high resolution imaging modes. In this paper, a novel 3D imaging method is proposed for airborne down-looking sparse array SAR based on the imaging geometry and the characteristic of echo signal. The key point of the proposed algorithm is the introduction of a special squint model in cross track processing to obtain accurate focusing. In this special squint model, point targets with different cross track positions have different squint angles at the same range resolution cell, which is different from the conventional squint SAR. However, after theory analysis and formulation deduction, the imaging procedure can be processed with the uniform reference function, and the phase compensation factors and algorithm realization procedure are demonstrated in detail. As the method requires only Fourier transform and multiplications and thus avoids interpolations, it is computationally efficient. Simulations with point scatterers are used to validate the method.

  17. Design methodology for a confocal imaging system using an objective microlens array with an increased working distance.

    Science.gov (United States)

    Choi, Woojae; Shin, Ryung; Lim, Jiseok; Kang, Shinill

    2016-09-12

    In this study, a design methodology for a multi-optical probe confocal imaging system was developed. To develop an imaging system that has the required resolving power and imaging area, this study focused on a design methodology to create a scalable and easy-to-implement confocal imaging system. This system overcomes the limitations of the optical complexities of conventional multi-optical probe confocal imaging systems and the short working distance using a micro-objective lens module composed of two microlens arrays and a telecentric relay optical system. The micro-objective lens module was fabricated on a glass substrate using backside alignment photolithography and thermal reflow processes. To test the feasibility of the developed methodology, an optical system with a resolution of 1 μm/pixel using multi-optical probes with an array size of 10 × 10 was designed and constructed. The developed system provides a 1 mm × 1 mm field of view and a sample scanning range of 100 μm. The optical resolution was evaluated by conducting sample tests using a knife-edge detecting method. The measured lateral resolution of the system was 0.98 μm.

  18. Imaging of the dynamic magnetic structure in a parallel array of shunted Josephson junctions

    DEFF Research Database (Denmark)

    Doderer, T.; Kaplunenko, V. K.; Mygind, Jesper

    1994-01-01

    A one-dimensional (1D) parallel array of shunted Josephson junctions is one of the basic elements in the family of rapid single-flux quantum logic circuits. It was found recently that current steps always show up in the current-voltage curve of the generator junction when an additional bias current...... is applied to the edge junction of the array. This effect was found to be due to the self-induced magnetic field produced by the edge current. This nonuniform field divides the array into domains each spanning several unit cells and each containing the same number of flux quanta. We report on experimental...

  19. Hot Spots Detection of Operating PV Arrays through IR Thermal Image Using Method Based on Curve Fitting of Gray Histogram

    Directory of Open Access Journals (Sweden)

    Jiang Lin

    2016-01-01

    Full Text Available The overall efficiency of PV arrays is affected by hot spots which should be detected and diagnosed by applying responsible monitoring techniques. The method using the IR thermal image to detect hot spots has been studied as a direct, noncontact, nondestructive technique. However, IR thermal images suffer from relatively high stochastic noise and non-uniformity clutter, so the conventional methods of image processing are not effective. The paper proposes a method to detect hotspots based on curve fitting of gray histogram. The result of MATLAB simulation proves the method proposed in the paper is effective to detect the hot spots suppressing the noise generated during the process of image acquisition.

  20. High resolution imaging of the Venus night side using a Rockwell 128x128 HgCdTe array

    Science.gov (United States)

    Hodapp, K.-W.; Sinton, W.; Ragent, B.; Allen, D.

    1989-01-01

    The University of Hawaii operates an infrared camera with a 128x128 HgCdTe detector array on loan from JPL's High Resolution Imaging Spectrometer (HIRIS) project. The characteristics of this camera system are discussed. The infrared camera was used to obtain images of the night side of Venus prior to and after inferior conjunction in 1988. The images confirm Allen and Crawford's (1984) discovery of bright features on the dark hemisphere of Venus visible in the H and K bands. Our images of these features are the best obtained to date. Researchers derive a pseudo rotation period of 6.5 days for these features and 1.74 microns brightness temperatures between 425 K and 480 K. The features are produced by nonuniform absorption in the middle cloud layer (47 to 57 Km altitude) of thermal radiation from the lower Venus atmosphere (20 to 30 Km altitude). A more detailed analysis of the data is in progress.

  1. Ambient Vehicular Noise recorded on a 2D Distributed Fiber Optic Sensing Array :Applications to Permafrost Thaw Detection and Imaging

    Science.gov (United States)

    Ajo Franklin, J. B.; Lindsey, N.; Wagner, A. M.; Dou, S.; Martin, E. R.; Ekblaw, I.; Ulrich, C.; James, S. R.; Freifeld, B. M.; Daley, T. M.

    2016-12-01

    Distributed Acoustic Sensing (DAS) is a recently developed technique that allows the spatially dense ( 1m) continuous recording of seismic signals on long strands of commercial fiber optic cables. The availability of continuous recording on dense arrays offers unique possibilities for long-term timelapse monitoring of environmental processes in arctic environments. In the absence of a repeatable semi-permanent seismic source, the use of ambient surface wave noise from infrastructure use (e.g. moving vehicles) for seismic imaging allows tomographic monitoring of evolving subsurface systems. Challenges in such scenarios include (1) the processing requirements for dense (1000+ channel) arrays recording weeks to months of seismic data, (2) appropriate methods to retrieve empirical noise correlation functions (NCFs) in environments with non-optimal array geometries and both coherent as well as incoherent noise, and (3) semi-automated approaches to invert timelapse NCFs for near-surface soil properties.We present an exploratory study of data from a sparse 2D DAS array acquisition on 4000 linear meters of trenched fiber deployed in 10 crossing profiles. The dataset, collected during July and August of 2016, covers a zone of permafrost undergoing a controlled thaw induced by an array of resistive heaters. The site, located near a heavily used road, has a high level of infrastructure noise but exhibits distance-dependent variation in both noise amplitude and spectrum. We apply seismic interferometry to retrieve the empirical NCF across array subsections, and use collocated geophone and broadband sensors to measure the NCF against the true impulse response function of the medium. We demonstrate that the combination of vehicle tracking and data windowing allows improved reconstruction of stable NCFs appropriate for dispersion analysis and inversion. We also show both spatial and temporal patterns of background noise at the site using 2D beamforming and spectral analysis. Our

  2. Design and Imaging of Ground-Based Multiple-Input Multiple-Output Synthetic Aperture Radar (MIMO SAR) with Non-Collinear Arrays.

    Science.gov (United States)

    Hu, Cheng; Wang, Jingyang; Tian, Weiming; Zeng, Tao; Wang, Rui

    2017-03-15

    Multiple-Input Multiple-Output (MIMO) radar provides much more flexibility than the traditional radar thanks to its ability to realize far more observation channels than the actual number of transmit and receive (T/R) elements. In designing the MIMO imaging radar arrays, the commonly used virtual array theory generally assumes that all elements are on the same line. However, due to the physical size of the antennas and coupling effect between T/R elements, a certain height difference between T/R arrays is essential, which will result in the defocusing of edge points of the scene. On the other hand, the virtual array theory implies far-field approximation. Therefore, with a MIMO array designed by this theory, there will exist inevitable high grating lobes in the imaging results of near-field edge points of the scene. To tackle these problems, this paper derives the relationship between target's point spread function (PSF) and pattern of T/R arrays, by which the design criterion is presented for near-field imaging MIMO arrays. Firstly, the proper height between T/R arrays is designed to focus the near-field edge points well. Secondly, the far-field array is modified to suppress the grating lobes in the near-field area. Finally, the validity of the proposed methods is verified by two simulations and an experiment.

  3. Super-resolution imaging of aquaporin-4 orthogonal arrays of particles in cell membranes

    National Research Council Canada - National Science Library

    Rossi, Andrea; Moritz, Tobias J; Ratelade, Julien; Verkman, A S

    2012-01-01

    Aquaporin-4 (AQP4) is a water channel expressed in astrocytes, skeletal muscle and epithelial cells that forms supramolecular aggregates in plasma membranes called orthogonal arrays of particles (OAPs...

  4. Megapixel mercury cadmium telluride focal plane arrays for infrared imaging out to 12 microns Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose the fabrication of large format, long wave infrared (LWIR) mercury cadmium telluride (HgCdTe or MCT) detector arrays where the cutoff wavelength is...

  5. High Performance Dual Band Photodetector Arrays for MWIR/LWIR Imaging Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposed Phase II program seeks to create dual-band pixel-collocated MWIR/LWIR photodetector arrays based on III-V semiconductor materials in a Type-II...

  6. Multistatic Array Sampling Scheme for Fast Near-Field Image Reconstruction

    Science.gov (United States)

    2016-01-01

    subjects in high foot traffic environments, such as mass transit systems, stadiums , and large public events. In order to handle a potentially constant...in [4], however, a key difference in this work is the sampling scheme. As will be discussed, the presented design samples the scene on a uniform phase...elementary unit of the design is the Boundary Array (BA) [6], a sparse array topology first used in ultrasonic sensing. This design employs four linear

  7. Accurate, precise modeling of cell proliferation kinetics from time-lapse imaging and automated image analysis of agar yeast culture arrays

    Directory of Open Access Journals (Sweden)

    Zhao Lue

    2007-01-01

    Full Text Available Abstract Background Genome-wide mutant strain collections have increased demand for high throughput cellular phenotyping (HTCP. For example, investigators use HTCP to investigate interactions between gene deletion mutations and additional chemical or genetic perturbations by assessing differences in cell proliferation among the collection of 5000 S. cerevisiae gene deletion strains. Such studies have thus far been predominantly qualitative, using agar cell arrays to subjectively score growth differences. Quantitative systems level analysis of gene interactions would be enabled by more precise HTCP methods, such as kinetic analysis of cell proliferation in liquid culture by optical density. However, requirements for processing liquid cultures make them relatively cumbersome and low throughput compared to agar. To improve HTCP performance and advance capabilities for quantifying interactions, YeastXtract software was developed for automated analysis of cell array images. Results YeastXtract software was developed for kinetic growth curve analysis of spotted agar cultures. The accuracy and precision for image analysis of agar culture arrays was comparable to OD measurements of liquid cultures. Using YeastXtract, image intensity vs. biomass of spot cultures was linearly correlated over two orders of magnitude. Thus cell proliferation could be measured over about seven generations, including four to five generations of relatively constant exponential phase growth. Spot area normalization reduced the variation in measurements of total growth efficiency. A growth model, based on the logistic function, increased precision and accuracy of maximum specific rate measurements, compared to empirical methods. The logistic function model was also more robust against data sparseness, meaning that less data was required to obtain accurate, precise, quantitative growth phenotypes. Conclusion Microbial cultures spotted onto agar media are widely used for genotype

  8. Locating non-volcanic tremor along the San Andreas Fault using a multiple array source imaging technique

    Science.gov (United States)

    Ryberg, T.; Haberland, C.H.; Fuis, G.S.; Ellsworth, W.L.; Shelly, D.R.

    2010-01-01

    Non-volcanic tremor (NVT) has been observed at several subduction zones and at the San Andreas Fault (SAF). Tremor locations are commonly derived by cross-correlating envelope-transformed seismic traces in combination with source-scanning techniques. Recently, they have also been located by using relative relocations with master events, that is low-frequency earthquakes that are part of the tremor; locations are derived by conventional traveltime-based methods. Here we present a method to locate the sources of NVT using an imaging approach for multiple array data. The performance of the method is checked with synthetic tests and the relocation of earthquakes. We also applied the method to tremor occurring near Cholame, California. A set of small-aperture arrays (i.e. an array consisting of arrays) installed around Cholame provided the data set for this study. We observed several tremor episodes and located tremor sources in the vicinity of SAF. During individual tremor episodes, we observed a systematic change of source location, indicating rapid migration of the tremor source along SAF. ?? 2010 The Authors Geophysical Journal International ?? 2010 RAS.

  9. Development of Very Long Baseline Interferometry (VLBI) techniques in New Zealand: Array simulation, image synthesis and analysis

    Science.gov (United States)

    Weston, S. D.

    2008-04-01

    This thesis presents the design and development of a process to model Very Long Base Line Interferometry (VLBI) aperture synthesis antenna arrays. In line with the Auckland University of Technology (AUT) Institute for Radiophysics and Space Research (IRSR) aims to develop the knowledge, skills and experience within New Zealand, extensive use of existing radio astronomical software has been incorporated into the process namely AIPS (Astronomical Imaging Processing System), MIRIAD (a radio interferometry data reduction package) and DIFMAP (a program for synthesis imaging of visibility data from interferometer arrays of radio telescopes). This process has been used to model various antenna array configurations for two proposed New Zealand sites for antenna in a VLBI array configuration with existing Australian facilities and a passable antenna at Scott Base in Antarctica; and the results are presented in an attempt to demonstrate the improvement to be gained by joint trans-Tasman VLBI observation. It is hoped these results and process will assist the planning and placement of proposed New Zealand radio telescopes for cooperation with groups such as the Australian Long Baseline Array (LBA), others in the Pacific Rim and possibly globally; also potential future involvement of New Zealand with the SKA. The developed process has also been used to model a phased building schedule for the SKA in Australia and the addition of two antennas in New Zealand. This has been presented to the wider astronomical community via the Royal Astronomical Society of New Zealand Journal, and is summarized in this thesis with some additional material. A new measure of quality ("figure of merit") for comparing the original model image and final CLEAN images by utilizing normalized 2-D cross correlation is evaluated as an alternative to the existing subjective visual operator image comparison undertaken to date by other groups. This new unit of measure is then used ! in the presentation of the

  10. Investigation of a CPG-array CdZnTe γ-ray imaging detector with single collecting electrodes readout.

    Science.gov (United States)

    Ma, Yuedong; Xiao, Shali; Yang, Guoqiang; Zhang, Liuqiang

    2015-11-01

    The single-electrode readout method has been applied to a coplanar grid (CPG) array CdZnTe detector in order to halve the number of preamplifiers previously needed and to facilitate imaging applications of CPG detectors. A method of predetermining the width of the optimum collecting electrodes has also been proposed, using the calculated optimum relative gain factor G. Meanwhile, a detailed process for calculating the charge induction efficiency (CIE) is presented. To simplify the calculation process, the computational formula of the CIE was deduced through the integration of the weighting potential. For performance evaluation, a 2 × 2 CPG-array CdZnTe detector was elaborately designed and tested with (137)Cs at 662 keV. Experimental results showed the capability of using the CPG-array CdZnTe detector with single collecting electrode readout for γ-ray imaging applications, with the same complexity of associated readout electronics as that of the pixelated CdZnTe detectors.

  11. Microwave Imaging Using CMOS Integrated Circuits with Rotating 4 × 4 Antenna Array on a Breast Phantom

    Directory of Open Access Journals (Sweden)

    Hang Song

    2017-01-01

    Full Text Available A digital breast cancer detection system using 65 nm technology complementary metal oxide semiconductor (CMOS integrated circuits with rotating 4 × 4 antenna array is presented. Gaussian monocycle pulses are generated by CMOS logic circuits and transmitted by a 4 × 4 matrix antenna array via two CMOS single-pole-eight-throw (SP8T switching matrices. Radar signals are received and converted to digital signals by CMOS equivalent time sampling circuits. By rotating the 4 × 4 antenna array, the reference signal is obtained by averaging the waveforms from various positions to extract the breast phantom target response. A signal alignment algorithm is proposed to compensate the phase shift of the signals caused by the system jitter. After extracting the scattered signal from the target, a bandpass filter is applied to reduce the noise caused by imperfect subtraction between original and the reference signals. The confocal imaging algorithm for rotating antennas is utilized to reconstruct the breast image. A 1 cm3 bacon block as a cancer phantom target in a rubber substrate as a breast fat phantom can be detected with reduced artifacts.

  12. Position and time-delay calibration of transducer elements in a sparse array for underwater ultrasound imaging.

    Science.gov (United States)

    Li, Yue

    2006-08-01

    This paper describes a novel method for the calibration of the position and time delay of transducer elements in a large, sparse array used for underwater, high-resolution ultrasound imaging. This method is based on the principles used in the global positioning system (GPS). However, unlike GPS, in which the wave propagation speed is generally assumed known, the sound propagation speed in the water usually is unknown and it is calibrated simultaneously in this method to achieve high calibration accuracy. In this method, a high-precision positioning system is used to scan a single hydrophone (used for transmission) in the imaging field of the array. The hydrophone transmits pulses at selected positions, and the transducer elements in the sparse array receive the transmitted signals. Time of flight (TOF) values between transducer elements and hydrophone positions then are measured. From a series of measured TOF values, the position and time delay values for each transducer element as well as the propagation speed can be calibrated. The performances of the calibration algorithm are theoretically analyzed and evaluated with numerical calculations and simulation studies. It is found that this method is capable of calibrating the positions and time delays of transducer elements with high accuracy.

  13. Nonlinear imaging (NIM) of flaws in a complex composite stiffened panel using a constructive nonlinear array (CNA) technique.

    Science.gov (United States)

    Malfense Fierro, Gian Piero; Meo, Michele

    2017-02-01

    Recently, there has been high interest in the capabilities of nonlinear ultrasound techniques for damage/defect detection as these techniques have been shown to be quite accurate in imaging some particular type of damage. This paper presents a Constructive Nonlinear Array (CNA) method, for the detection and imaging of material defects/damage in a complex composite stiffened panel. CNA requires the construction of an ultrasound array in a similar manner to standard phased arrays systems, which require multiple transmitting and receiving elements. The method constructively phase-match multiple captured signals at a particular position given multiple transmit positions, similar to the total focusing method (TFM) method. Unlike most of the ultrasonic linear techniques, a longer excitation signal was used to achieve a steady-state excitation at each capturing position, so that compressive and tensile stress at defect/crack locations increases the likelihood of the generation of nonlinear elastic waves. Moreover, the technique allows the reduction of instrumentation nonlinear wave generation by relying on signal attenuation to naturally filter these errors. Experimental tests were carried out on a stiffened panel with manufacturing defects. Standard industrial linear ultrasonic test were carried out for comparison. The proposed new method allows to image damages/defects in a reliable and reproducible manner and overcomes some of the main limitations of nonlinear ultrasound techniques. In particular, the effectiveness and robustness of CNA and the advantages over linear ultrasonic were clearly demonstrated allowing a better resolution and imaging of complex and realistic flaws. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Quantitative Analysis of Rat Dorsal Root Ganglion Neurons Cultured on Microelectrode Arrays Based on Fluorescence Microscopy Image Processing.

    Science.gov (United States)

    Mari, João Fernando; Saito, José Hiroki; Neves, Amanda Ferreira; Lotufo, Celina Monteiro da Cruz; Destro-Filho, João-Batista; Nicoletti, Maria do Carmo

    2015-12-01

    Microelectrode Arrays (MEA) are devices for long term electrophysiological recording of extracellular spontaneous or evocated activities on in vitro neuron culture. This work proposes and develops a framework for quantitative and morphological analysis of neuron cultures on MEAs, by processing their corresponding images, acquired by fluorescence microscopy. The neurons are segmented from the fluorescence channel images using a combination of segmentation by thresholding, watershed transform, and object classification. The positioning of microelectrodes is obtained from the transmitted light channel images using the circular Hough transform. The proposed method was applied to images of dissociated culture of rat dorsal root ganglion (DRG) neuronal cells. The morphological and topological quantitative analysis carried out produced information regarding the state of culture, such as population count, neuron-to-neuron and neuron-to-microelectrode distances, soma morphologies, neuron sizes, neuron and microelectrode spatial distributions. Most of the analysis of microscopy images taken from neuronal cultures on MEA only consider simple qualitative analysis. Also, the proposed framework aims to standardize the image processing and to compute quantitative useful measures for integrated image-signal studies and further computational simulations. As results show, the implemented microelectrode identification method is robust and so are the implemented neuron segmentation and classification one (with a correct segmentation rate up to 84%). The quantitative information retrieved by the method is highly relevant to assist the integrated signal-image study of recorded electrophysiological signals as well as the physical aspects of the neuron culture on MEA. Although the experiments deal with DRG cell images, cortical and hippocampal cell images could also be processed with small adjustments in the image processing parameter estimation.

  15. Real-time micro-vibration multi-spot synchronous measurement within a region based on heterodyne interference

    Science.gov (United States)

    Lan, Ma; Xiao, Wen; Chen, Zonghui; Hao, Hongliang; Pan, Feng

    2018-01-01

    Real-time micro-vibration measurement is widely used in engineering applications. It is very difficult for traditional optical detection methods to achieve real-time need in a relatively high frequency and multi-spot synchronous measurement of a region at the same time,especially at the nanoscale. Based on the method of heterodyne interference, an experimental system of real-time measurement of micro - vibration is constructed to satisfy the demand in engineering applications. The vibration response signal is measured by combing optical heterodyne interferometry and a high-speed CMOS-DVR image acquisition system. Then, by extracting and processing multiple pixels at the same time, four digital demodulation technique are implemented to simultaneously acquire the vibrating velocity of the target from the recorded sequences of images. Different kinds of demodulation algorithms are analyzed and the results show that these four demodulation algorithms are suitable for different interference signals. Both autocorrelation algorithm and cross-correlation algorithm meet the needs of real-time measurements. The autocorrelation algorithm demodulates the frequency more accurately, while the cross-correlation algorithm is more accurate in solving the amplitude.

  16. Near-infrared Compressive Line Sensing Imaging System using Individually Addressable Laser Diode Array

    Science.gov (United States)

    2015-05-11

    Salmon, K. G. Cooper, "Development and testing of a synchronous-scanning underwater imaging system capable of rapid two-dimensional frame imaging,", Appl...Opt. Jul 1;32(19):3520-30, 1993. [12] B. C. Redman, A. J. Griffis, and E. B. Schibley, “Streak Tube Imaging Lidar ( STIL ) for 3-D Imaging of

  17. Free-Space Quantum Signatures Using Heterodyne Measurements.

    Science.gov (United States)

    Croal, Callum; Peuntinger, Christian; Heim, Bettina; Khan, Imran; Marquardt, Christoph; Leuchs, Gerd; Wallden, Petros; Andersson, Erika; Korolkova, Natalia

    2016-09-02

    Digital signatures guarantee the authorship of electronic communications. Currently used "classical" signature schemes rely on unproven computational assumptions for security, while quantum signatures rely only on the laws of quantum mechanics to sign a classical message. Previous quantum signature schemes have used unambiguous quantum measurements. Such measurements, however, sometimes give no result, reducing the efficiency of the protocol. Here, we instead use heterodyne detection, which always gives a result, although there is always some uncertainty. We experimentally demonstrate feasibility in a real environment by distributing signature states through a noisy 1.6 km free-space channel. Our results show that continuous-variable heterodyne detection improves the signature rate for this type of scheme and therefore represents an interesting direction in the search for practical quantum signature schemes. For transmission values ranging from 100% to 10%, but otherwise assuming an ideal implementation with no other imperfections, the signature length is shorter by a factor of 2 to 10. As compared with previous relevant experimental realizations, the signature length in this implementation is several orders of magnitude shorter.

  18. Teaching real-time ultrasonic imaging with a 4-channel sonar array, TI C6711 DSK and MATLAB.

    Science.gov (United States)

    York, George W P; Welch, Thad B; Wright, Cameron H G

    2005-01-01

    Ultrasonic medical imaging courses often stop at the theory or MATLAB simulation level, since professors find it challenging to give the students the experience of designing a real-time ultrasonic system. Some of the practical problems of working with real-time data from the ultrasonic transducers can be avoided by working at lower frequencies (sonar to low ultrasound) range. To facilitate this, we have created a platform using the ease of MATLAB programming with the real-time processing capability of the low-cost Texas Instruments C6711 DSP starter kit and a 4-channel sonar array. With this platform students can design a B-mode or Color-Mode sonar system in the MATLAB environment. This paper will demonstrate how the platform can be used in the classroom to demonstrate the real-time signal processing stages including beamforming, multi-rate sampling, demodulation, filtering, image processing, echo imaging, and Doppler frequency estimation.

  19. On-Demand Formation of Supported Lipid Membrane Arrays by Trehalose-Assisted Vesicle Delivery for SPR Imaging.

    Science.gov (United States)

    Hinman, Samuel S; Ruiz, Charles J; Drakakaki, Georgia; Wilkop, Thomas E; Cheng, Quan

    2015-08-12

    The fabrication of large-scale, solid-supported lipid bilayer (SLB) arrays has traditionally been an arduous and complex task, primarily due to the need to maintain SLBs within an aqueous environment. In this work, we demonstrate the use of trehalose vitrified phospholipid vesicles that facilitate on-demand generation of microarrays, allowing each element a unique composition, for the label-free and high-throughput analysis of biomolecular interactions by SPR imaging (SPRi). Small, unilamellar vesicles (SUVs) are suspended in trehalose, deposited in a spatially defined manner, with the trehalose vitrifying on either hydrophilic or hydrophobic SPR substrates. SLBs are subsequently spontaneously formed on-demand simply by in situ hydration of the array in the SPR instrument flow cell. The resulting SLBs exhibit high lateral mobility, characteristic of fluidic cellular lipid membranes, and preserve the biological function of embedded cell membrane receptors, as indicated by SPR affinity measurements. Independent fluorescence and SPR imaging studies show that the individual SLBs stay localized at the area of deposition, without any encapsulating matrix, confining coral, or boundaries. The introduced methodology allows individually addressable SLB arrays to be analyzed with excellent label-free sensitivity in a real-time, high-throughput manner. Various protein-ganglioside interactions have been selected as a model system to illustrate discrimination of strong and weak binding responses in SPRi sensorgrams. This methodology has been applied toward generating hybrid bilayer membranes on hydrophobic SPR substrates, demonstrating its versatility toward a range of surfaces and membrane geometries. The stability of the fabricated arrays, over medium to long storage periods, was evaluated and found to be good. The highly efficient and easily scalable nature of the method has the potential to be applied to a variety of label-free sensing platforms requiring lipid membranes for

  20. Development of Eu:SrI2 Scintillator Array for Gamma-Ray Imaging Applications

    Science.gov (United States)

    Yoshino, Masao; Kamada, Kei; Shoji, Yasuhiro; Kurosawa, Shunsuke; Yokota, Yuui; Ohashi, Yuji; Yoshikawa, Akira; Yamamoto, Seiichi

    2017-07-01

    Eu:SrI2 bulk single crystals with 1.5-in diameter were grown using the Bridgman-Stockbarger technique and special-shaped crucibles. We will report on the growth of the 1.5-in size Eu:SrI2 single crystal and the preliminary test of the same sample cut in size of 10×10×10 mm3 with polishing. An energy resolution of 3.2% full width at half maximum (FWHM) was obtained for 137Cs. After cutting and polishing the grown crystal to the size of 3×3×3 mm3, 8×8 matrix Eu:SrI2 arrays were fabricated. We made a test module consisting of Eu:SrI2 arrays, which was optically coupled with position sensitive photomultiplier tube (PSPMT) and multi-pixel photon counter (MPPC) array. The position and energy performance of the test module were evaluated using 137Cs and 57Co radioactive sources. As a result, we were able to resolve all pixels clearly. A good energy resolution of 6.7% ± 0.7% (FWHM) and 8.2% ± 2.5% (FWHM) for 662 keV was obtained using PSPMT and MPPC arrays, respectively. In the same way, energy resolution of 12.7% ± 1.3% and 14.7% ± 3.4% (FWHM) for 122 keV was obtained using PSPMT and MPPC-array, respectively. These energy resolutions considerably degraded compared with an energy resolution of the single piece of Eu:SrI2 sample owing to the thinness of the Teflon reflector. This conclusion can be considered as a strong motivation for future research on the choice of reflector materials and structure of the Eu:SrI2 array.

  1. Characterization of NIR InGaAs imager arrays for the JDEM SNAP mission concept

    OpenAIRE

    Seshadri, S; Cole, M D; Hancock, B.; Ringold, P.; Wrigley, C; Bonati, M.; Brown, M. G.; Schubnell, M.; Rahmer, G.; Guzman, D.; Figer, D.; Tarle, G; Smith, R M; Bebek, C.

    2006-01-01

    We present the results of a study of the performance of InGaAs detectors conducted for the SuperNova Acceleration Probe (SNAP) dark energy mission concept. Low temperature data from a nominal 1.7um cut-off wavelength 1kx1k InGaAs photodiode array, hybridized to a Rockwell H1RG multiplexer suggest that InGaAs detector performance is comparable to those of existing 1.7um cut-off HgCdTe arrays. Advances in 1.7um HgCdTe dark current and noise initiated by the SNAP detector research and devel...

  2. OpenMSI Arrayed Analysis Toolkit: Analyzing Spatially Defined Samples Using Mass Spectrometry Imaging

    DEFF Research Database (Denmark)

    de Raad, Markus; de Rond, Tristan; Rübel, Oliver

    2017-01-01

    ://openmsinersc.gov), a platform for storing, sharing, and analyzing MSI data. By using a web-based python notebook (Jupyter), OMAAT is accessible to anyone without programming experience yet allows experienced users to leverage all features. OMAAT was :evaluated by analyzing an MSI data set of a high-throughput glycoside...... processing tools for the analysis of large arrayed MSI sample sets. The OpenMSI Arrayed Analysis Toolkit (OMAAT) is a software package that addresses the challenges of analyzing spatially defined samples in MSI data sets. OMAAT is written in Python and is integrated with OpenMSI (http...

  3. FPGA-Based Smart Sensor for Online Displacement Measurements Using a Heterodyne Interferometer

    Science.gov (United States)

    Vera-Salas, Luis Alberto; Moreno-Tapia, Sandra Veronica; Garcia-Perez, Arturo; de Jesus Romero-Troncoso, Rene; Osornio-Rios, Roque Alfredo; Serroukh, Ibrahim; Cabal-Yepez, Eduardo

    2011-01-01

    The measurement of small displacements on the nanometric scale demands metrological systems of high accuracy and precision. In this context, interferometer-based displacement measurements have become the main tools used for traceable dimensional metrology. The different industrial applications in which small displacement measurements are employed requires the use of online measurements, high speed processes, open architecture control systems, as well as good adaptability to specific process conditions. The main contribution of this work is the development of a smart sensor for large displacement measurement based on phase measurement which achieves high accuracy and resolution, designed to be used with a commercial heterodyne interferometer. The system is based on a low-cost Field Programmable Gate Array (FPGA) allowing the integration of several functions in a single portable device. This system is optimal for high speed applications where online measurement is needed and the reconfigurability feature allows the addition of different modules for error compensation, as might be required by a specific application. PMID:22164040

  4. Potential of a superconducting photon counter for heterodyne detection at the telecommunication wavelength.

    Science.gov (United States)

    Shcherbatenko, M; Lobanov, Y; Semenov, A; Kovalyuk, V; Korneev, A; Ozhegov, R; Kazakov, A; Voronov, B M; Goltsman, G N

    2016-12-26

    Here, we report on the successful operation of a NbN thin film superconducting nanowire single-photon detector (SNSPD) in a coherent mode (as a mixer) at the telecommunication wavelength of 1550 nm. Providing the local oscillator power of the order of a few picowatts, we were practically able to reach the quantum noise limited sensitivity. The intermediate frequency gain bandwidth (also referred to as response or conversion bandwidth) was limited by the spectral band of a single-photon response pulse of the detector, which is proportional to the detector size. We observed a gain bandwidth of 65 MHz and 140 MHz for 7 × 7 µm2 and 3 × 3 µm2 devices, respectively. A tiny amount of the required local oscillator power and wide gain and noise bandwidths, along with unnecessary low noise amplification, make this technology prominent for various applications, with the possibility for future development of a photon counting heterodyne-born large-scale array.

  5. Estimation and application of 2-D scattering matrices for sparse array imaging of simulated damage in composite panels

    Science.gov (United States)

    Williams, Westin B.; Michaels, Thomas E.; Michaels, Jennifer E.

    2017-02-01

    Reliable detection of damage in composites is critically important for failure prevention in the aerospace industry since these materials are more frequently being used in high stress applications. Structural health monitoring (SHM) via guided wave sensors mounted on or embedded within a composite structure can help detect and localize damage in real-time while potentially reducing overall maintenance costs. One approach to guided wave SHM is sparse array imaging via the minimum variance algorithm, and it has been shown in prior work that incorporating expected scattering from defects of interest can improve the quality of damage localization and characterization. For this study, simulated damage in the form of attached magnets was used for estimating scattering from recorded wavefield data. Data were recorded on a circle centered at the damage location from multiple incident directions before and after the magnets were attached. Baseline subtraction is used to estimate scattering patterns for each incident direction, and these patterns are combined and interpolated to form a full 2-D scattering matrix. This matrix is then incorporated into the minimum variance imaging algorithm, and the efficacy of this scattering estimation methodology is evaluated by comparing the resulting sparse array images to those generated using simpler scattering assumptions.

  6. Solid-State Multi-Sensor Array System for Real Time Imaging of Magnetic Fields and Ferrous Objects

    Science.gov (United States)

    Benitez, D.; Gaydecki, P.; Quek, S.; Torres, V.

    2008-02-01

    In this paper the development of a solid-state sensors based system for real-time imaging of magnetic fields and ferrous objects is described. The system comprises 1089 magneto inductive solid state sensors arranged in a 2D array matrix of 33×33 files and columns, equally spaced in order to cover an approximate area of 300 by 300 mm. The sensor array is located within a large current-carrying coil. Data is sampled from the sensors by several DSP controlling units and finally streamed to a host computer via a USB 2.0 interface and the image generated and displayed at a rate of 20 frames per minute. The development of the instrumentation has been complemented by extensive numerical modeling of field distribution patterns using boundary element methods. The system was originally intended for deployment in the non-destructive evaluation (NDE) of reinforced concrete. Nevertheless, the system is not only capable of producing real-time, live video images of the metal target embedded within any opaque medium, it also allows the real-time visualization and determination of the magnetic field distribution emitted by either permanent magnets or geometries carrying current. Although this system was initially developed for the NDE arena, it could also have many potential applications in many other fields, including medicine, security, manufacturing, quality assurance and design involving magnetic fields.

  7. Design and performance of a low noise, 128-channel ASIC preamplifier for readout of active matrix flat-panel imaging arrays

    CERN Document Server

    Maolinbay, M; Yarema, R J; Antonuk, L E; El-Mohri, Y; Yeakey, M

    2002-01-01

    Design architecture and performance measurements of a low noise, 128-channel application-specific-integrated-circuit (ASIC) preamplifier are reported. The ASIC was designed for readout of active matrix flat-panel imager (AMFPI) arrays. Such arrays, which presently can be made as large as 41 cmx41 cm and with pixel-to-pixel pitches down to approx 70 mu m, require large numbers of low noise, high density, custom integrated readout circuits. The design of this new chip is specifically tailored for research and development of active matrix flat-panel arrays for various medical imaging applications. The design architecture includes the following features: (1) Programmable signal gain which allows acquisition of a wide range of signal sizes from various array designs so as to optimize the signal-to-noise ratio; (2) Correlated double sampling (CDS) which significantly reduces certain noise components; (3) Pipelined readout (simultaneously sampling and multiplexing signals) which reduces image acquisition time; (4) P...

  8. Improving the resolution of three-dimensional acoustic imaging with planar phased arrays

    DEFF Research Database (Denmark)

    Xenaki, Angeliki; Jacobsen, Finn; Fernandez Grande, Efren

    2012-01-01

    This paper examines and compares two methods of improving the quality of three-dimensional beamforming with phased microphone arrays. The intended application is the detection of aerodynamic noise sources on wind turbines. Both methods employ Fourier based deconvolution. The first method involves...

  9. Transfer-printing of single DNA molecule arrays on graphene for high resolution electron imaging and analysis

    Science.gov (United States)

    Cerf, Aline; Alava, Thomas; Barton, Robert A.; Craighead, Harold G.

    2011-01-01

    Graphene represents the ultimate substrate for high-resolution transmission electron microscopy, but the deposition of biological samples on this highly hydrophobic material has until now been a challenge. We present a reliable method for depositing ordered arrays of individual elongated DNA molecules on single-layer graphene substrates for high resolution electron beam imaging and electron energy loss spectroscopy analysis. This method is a necessary step towards the observation of single elongated DNA molecules with single base spatial resolution to directly read genetic and epigenetic information. PMID:21919532

  10. Transfer-printing of single DNA molecule arrays on graphene for high-resolution electron imaging and analysis.

    Science.gov (United States)

    Cerf, Aline; Alava, Thomas; Barton, Robert A; Craighead, Harold G

    2011-10-12

    Graphene represents the ultimate substrate for high-resolution transmission electron microscopy, but the deposition of biological samples on this highly hydrophobic material has until now been a challenge. We present a reliable method for depositing ordered arrays of individual elongated DNA molecules on single-layer graphene substrates for high-resolution electron beam imaging and electron energy loss spectroscopy analysis. This method is a necessary step toward the observation of single elongated DNA molecules with single base spatial resolution to directly read genetic and epigenetic information.

  11. Integrated infrared array technology

    Science.gov (United States)

    Goebel, J. H.; Mccreight, C. R.

    1987-01-01

    An overview of integrated infrared (IR) array technology is presented. Although the array pixel formats are smaller, and the readout noise of IR arrays is larger than the corresponding values achieved with optical charge-coupled-device silicon technology, substantial progress is being made in IR technology. Both existing IR arrays and those being developed are described. Examples of astronomical images are given which illustrate the potential of integrated IR arrays for scientific investigations.

  12. Laser tweezer actuated microphotonic array devices for high resolution imaging and analysis in chip-based biosystems

    Science.gov (United States)

    Birkbeck, Aaron L.

    A new technology is developed that functionally integrates arrays of lasers and micro-optics into microfluidic systems for the purpose of imaging, analyzing, and manipulating objects and biological cells. In general, the devices and technologies emerging from this area either lack functionality through the reliance on mechanical systems or provide a serial-based, time consuming approach. As compared to the current state of art, our all-optical design methodology has several distinguishing features, such as parallelism, high efficiency, low power, auto-alignment, and high yield fabrication methods, which all contribute to minimizing the cost of the integration process. The potential use of vertical cavity surface emitting lasers (VCSELs) for the creation of two-dimensional arrays of laser optical tweezers that perform independently controlled, parallel capture, and transport of large numbers of individual objects and biological cells is investigated. One of the primary biological applications for which VCSEL array sourced laser optical tweezers are considered is the formation of engineered tissues through the manipulation and spatial arrangement of different types of cells in a co-culture. Creating devices that combine laser optical tweezers with select micro-optical components permits optical imaging and analysis functions to take place inside the microfluidic channel. One such device is a micro-optical spatial filter whose motion and alignment is controlled using a laser optical tweezer. Unlike conventional spatial filter systems, our device utilizes a refractive optical element that is directly incorporated onto the lithographically patterned spatial filter. This allows the micro-optical spatial filter to automatically align itself in three-dimensions to the focal point of the microscope objective, where it then filters out the higher frequency additive noise components present in the laser beam. As a means of performing high resolution imaging in the

  13. Electronic intraoral dental x-ray imaging system employing a direct sensing CCD array

    Energy Technology Data Exchange (ETDEWEB)

    Cox, J.D.; Langford, D.S.; Williams, D.W. [General Imaging Corp., Gainesville, FL (United States)

    1993-12-31

    A commercial prototype intraoral radiography system has been developed that can provide digital x-ray images for diagnosis. The system consists of an intraoral detector head, an intermediate drive electronics package, a main drive electronics package and a PC-based digital image management system. The system has the potential to replace the use of dental film in intraoral radiographic examinations. High-resolution images are acquired, then displayed on a CRT within seconds of image acquisition.

  14. Electronic intraoral dental x-ray imaging system employing a direct-sensing CCD array

    Science.gov (United States)

    Cox, John D.; Langford, D. S.; Williams, Donald W.

    1993-12-01

    A commercial prototype intraoral radiography system has been developed that can provide digital x-ray images for diagnosis. The system consists of an intraoral detector head, an intermediate drive electronics package, a main drive electronics package, and a PC-based digital image management system. The system has the potential to replace the use of dental film in intraoral radiographic examinations. High-resolution images are acquired, then displayed on a CRT within seconds of image acquisition.

  15. Preliminary In-Vivo Evaluation of Convex Array Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Pedersen, Morten Høgholm; Gammelmark, Kim; Jensen, Jørgen Arendt

    2004-01-01

    sinusoid excitation pulse. Conventional and STA images were acquired interleaved yielding ensuring exact same anatomical location. Image sequences were recorded in real-time, and processing was done offline. Male volunteers were scanned abdominally, and resulting images were compared by medical doctors...

  16. Calcium Imaging of GPCR Activation Using Arrays of Reverse Transfected HEK293 Cells in a Microfluidic System.

    Science.gov (United States)

    Roelse, Margriet; Henquet, Maurice G L; Verhoeven, Harrie A; de Ruijter, Norbert C A; Wehrens, Ron; van Lenthe, Marco S; Witkamp, Renger F; Hall, Robert D; Jongsma, Maarten A

    2018-02-16

    Reverse-transfected cell arrays in microfluidic systems have great potential to perform large-scale parallel screening of G protein-coupled receptor (GPCR) activation. Here, we report the preparation of a novel platform using reverse transfection of HEK293 cells, imaging by stereo-fluorescence microscopy in a flowcell format, real-time monitoring of cytosolic calcium ion fluctuations using the fluorescent protein Cameleon and analysis of GPCR responses to sequential sample exposures. To determine the relationship between DNA concentration and gene expression, we analyzed cell arrays made with variable concentrations of plasmid DNA encoding fluorescent proteins and the Neurokinin 1 (NK1) receptor. We observed pronounced effects on gene expression of both the specific and total DNA concentration. Reverse transfected spots with NK1 plasmid DNA at 1% of total DNA still resulted in detectable NK1 activation when exposed to its ligand. By varying the GPCR DNA concentration in reverse transfection, the sensitivity and robustness of the receptor response for sequential sample exposures was optimized. An injection series is shown for an array containing the NK1 receptor, bitter receptor TAS2R8 and controls. Both receptors were exposed 14 times to alternating samples of two ligands. Specific responses remained reproducible. This platform introduces new opportunities for high throughput screening of GPCR libraries.

  17. Investigation of high-resolution functional magnetic resonance imaging by means of surface and array radiofrequency coils at 7 T.

    Science.gov (United States)

    van der Zwaag, Wietske; Marques, José P; Hergt, Martin; Gruetter, Rolf

    2009-10-01

    In this investigation, high-resolution, 1x1x1-mm(3) functional magnetic resonance imaging (fMRI) at 7 T is performed using a multichannel array head coil and a surface coil approach. Scan geometry was optimized for each coil separately to exploit the strengths of both coils. Acquisitions with the surface coil focused on partial brain coverage, while whole-brain coverage fMRI experiments were performed with the array head coil. BOLD sensitivity in the occipital lobe was found to be higher with the surface coil than with the head array, suggesting that restriction of signal detection to the area of interest may be beneficial for localized activation studies. Performing independent component analysis (ICA) decomposition of the fMRI data, we consistently detected BOLD signal changes and resting state networks. In the surface coil data, a small negative BOLD response could be detected in these resting state network areas. Also in the data acquired with the surface coil, two distinct components of the positive BOLD signal were consistently observed. These two components were tentatively assigned to tissue and venous signal changes.

  18. Noise Immune Cavity Enhanced Optical Heterodyne Velocity Modulation Spectroscopy

    Science.gov (United States)

    Siller, Brian; Mills, Andrew; Porambo, Michael; McCall, Benjamin

    2011-06-01

    The technique of Cavity Enhanced Velocity Modulation Spectroscopy (CEVMS) has recently been developed. By demodulating the detector signal at twice the plasma modulation frequency (2f), the velocity-modulated ionic absorption signal can be extracted. Although the concentration-modulated excited neutral molecules are also observed at 2f, the ion and neutral signals can be distinguished and separated with phase-sensitive demodulation. The optical cavity provides two major benefits. It increases both the optical path length and the intracavity laser power by a factor of 2×Finesse/π. The multipass advantage allows for much longer path length than was previously possible with unidirectional multipass White cells. The power enhancement combined with perfectly overlapped counterpropagating beams within the cavity allows for sub-Doppler spectroscopy. Although CEVMS showed much potential, its sensitivity was ultimately limited by electronic noise from the plasma interfering with the cavity-locking electronics. We have further improved upon CEVMS by combining it with Noise Immune Cavity Enhanced Optical Heterodyne Molecular Spectroscopy (NICE-OHMS). The laser is frequency modulated at precisely an integer multiple of the free spectral range of the optical cavity; this allows the heterodyne sidebands to be coupled into the optical cavity. Heterodyne detection of the cavity leak-out is immune to noise in the laser-cavity lock, and 2f demodulation further decreases electronic noise in the system and retains ion-neutral discrimination. The additional level of modulation beyond ordinary CEVMS has the added advantage of enabling the observation of both absorption and dispersion signals simultaneously by using two RF mixers, each driving its own lock-in amplifier. In a single scan, four distinct signals can be obtained: absorption and dispersion for ions and excited neutrals. The technique has been demonstrated in the near-IR for N_2^+. B. M. Siller, A. A. Mills and B. J. Mc

  19. Design and application of combined 8-channel transmit and 10-channel receive arrays and radiofrequency shimming for 7-T shoulder magnetic resonance imaging.

    Science.gov (United States)

    Brown, Ryan; Deniz, Cem Murat; Zhang, Bei; Chang, Gregory; Sodickson, Daniel K; Wiggins, Graham C

    2014-01-01

    The objective of the study was to investigate the feasibility of 7-T shoulder magnetic resonance imaging by developing transmit and receive radiofrequency (RF) coil arrays and exploring RF shim methods. A mechanically flexible 8-channel transmit array and an anatomically conformable 10-channel receive array were designed and implemented. The transmit performance of various RF shim methods was assessed through local flip angle measurements in the right and left shoulders of 6 subjects. The receive performance was assessed through signal-to-noise ratio measurements using the developed 7-T coil and a baseline commercial 3-T coil. The 7-T transmit array driven with phase-coherent RF shim weights provided adequate B₁⁺ efficiency and uniformity for turbo spin echo shoulder imaging. B₁⁺ twisting that is characteristic of high-field loop coils necessitates distinct RF shim weights in the right and left shoulders. The 7-T receive array provided a 2-fold signal-to-noise ratio improvement over the 3-T array in the deep articular shoulder cartilage. Shoulder imaging at 7-T is feasible with a custom transmit/receive array either in a single-channel transmit mode with a fixed RF shim or in a parallel transmit mode with a subject-specific RF shim.

  20. Imaging, object detection, and change detection with a polarized multistatic GPR array

    Energy Technology Data Exchange (ETDEWEB)

    Beer, N. Reginald; Paglieroni, David W.

    2015-07-21

    A polarized detection system performs imaging, object detection, and change detection factoring in the orientation of an object relative to the orientation of transceivers. The polarized detection system may operate on one of several modes of operation based on whether the imaging, object detection, or change detection is performed separately for each transceiver orientation. In combined change mode, the polarized detection system performs imaging, object detection, and change detection separately for each transceiver orientation, and then combines changes across polarizations. In combined object mode, the polarized detection system performs imaging and object detection separately for each transceiver orientation, and then combines objects across polarizations and performs change detection on the result. In combined image mode, the polarized detection system performs imaging separately for each transceiver orientation, and then combines images across polarizations and performs object detection followed by change detection on the result.

  1. MRI of the wrist at 7 tesla using an eight-channel array coil combined with parallel imaging: preliminary results.

    Science.gov (United States)

    Chang, Gregory; Friedrich, Klaus M; Wang, Ligong; Vieira, Renata L R; Schweitzer, Mark E; Recht, Michael P; Wiggins, Graham C; Regatte, Ravinder R

    2010-03-01

    To determine the feasibility of performing MRI of the wrist at 7 Tesla (T) with parallel imaging and to evaluate how acceleration factors (AF) affect signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and image quality. This study had institutional review board approval. A four-transmit eight-receive channel array coil was constructed in-house. Nine healthy subjects were scanned on a 7T whole-body MR scanner. Coronal and axial images of cartilage and trabecular bone micro-architecture (3D-Fast Low Angle Shot (FLASH) with and without fat suppression, repetition time/echo time = 20 ms/4.5 ms, flip angle = 10 degrees , 0.169-0.195 x 0.169-0.195 mm, 0.5-1 mm slice thickness) were obtained with AF 1, 2, 3, 4. T1-weighted fast spin-echo (FSE), proton density-weighted FSE, and multiple-echo data image combination (MEDIC) sequences were also performed. SNR and CNR were measured. Three musculoskeletal radiologists rated image quality. Linear correlation analysis and paired t-tests were performed. At higher AF, SNR and CNR decreased linearly for cartilage, muscle, and trabecular bone (r < -0.98). At AF 4, reductions in SNR/CNR were:52%/60% (cartilage), 72%/63% (muscle), 45%/50% (trabecular bone). Radiologists scored images with AF 1 and 2 as near-excellent, AF 3 as good-to-excellent (P = 0.075), and AF 4 as average-to-good (P = 0.11). It is feasible to perform high resolution 7T MRI of the wrist with parallel imaging. SNR and CNR decrease with higher AF, but image quality remains above-average.

  2. Nanoscale localization sampling based on nanoantenna arrays for super-resolution imaging of fluorescent monomers on sliding microtubules.

    Science.gov (United States)

    Kim, Kyujung; Yajima, Junichiro; Oh, Youngjin; Lee, Wonju; Oowada, Shinsuke; Nishizaka, Takayuki; Kim, Donghyun

    2012-03-26

    Sub-diffraction-limited imaging of fluorescent monomers on sliding microtubules in vitro by nanoscale localization sampling (NLS) is reported. NLS is based on periodic nanohole antenna arrays that create locally amplified electromagnetic hot spots through surface plasmon localization. The localized near-field hot spot temporally samples microtubular movement for enhanced spatial resolution. A fourfold improvement in spatial resolution compared to conventional wide-field microscopy is demonstrated. The resolution enhancement is achieved by imaging rhodamine-labeled microtubules that are sampled by the hot spots to provide sub-diffraction-limited images at 76 nm resolution in the direction of movement and 135 nm orthogonally. The intensity distribution produced by the NLS is measured to be broader than that of conventional imaging, which is consistent with the improvement of imaging resolution. Correlation studies between neighboring nanoantennas are also performed. This confirms the possibility of measuring microtubular transport dynamics. NLS can be useful for moving objects that have a high labeling density or for performing fluctuation spectroscopy in small volumes, and may allow "super-resolution on demand" by customizing nanoantenna structures for specific resolution needs. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Temporal resolution in electrochemical imaging on single PC12 cells using amperometry and voltammetry at microelectrode arrays.

    Science.gov (United States)

    Zhang, Bo; Heien, Michael L A V; Santillo, Michael F; Mellander, Lisa; Ewing, Andrew G

    2011-01-15

    Carbon-fiber-microelectrode arrays (MEAs) have been utilized to electrochemically image neurochemical secretion from individual pheochromocytoma (PC12) cells. Dopamine release events were electrochemically monitored from seven different locations on single PC12 cells using alternately constant-potential amperometry and fast-scan cyclic voltammetry (FSCV). Cyclic voltammetry, when compared to amperometry, can provide excellent chemical resolution; however, spatial and temporal resolution are both compromised. The spatial and temporal resolution of these two methods have been quantitatively compared and the differences explained using models of molecular diffusion at the nanogap between the electrode and the cell. A numerical simulation of the molecular flux reveals that the diffusion of dopamine molecules and electrochemical reactions both play important roles in the temporal resolution of electrochemical imaging. The simulation also reveals that the diffusion and electrode potential cause the differences in signal crosstalk between electrodes when comparing amperometry and FSCV.

  4. Characterization of NIR InGaAs imager arrays for the JDEM SNAPmission concept

    Energy Technology Data Exchange (ETDEWEB)

    Seshadri, S.; Cole, M.D.; Hancock, B.; Ringold, P.; Wrigley, C.; Bonati, M.; Brown, M.G.; Schubnell, M.; Rahmer, G.; Guzman, D.; Figer,D.; Tarle, G.; Smith, R.M.; Bebek, C.

    2006-05-23

    We present the results of a study of the performance of InGaAs detectors conducted for the SuperNova Acceleration Probe (SNAP) dark energy mission concept. Low temperature data from a nominal 1.7um cut-off wavelength 1kx1k InGaAs photodiode array, hybridized to a Rockwell H1RG multiplexer suggest that InGaAs detector performance is comparable to those of existing 1.7um cut-off HgCdTe arrays. Advances in 1.7um HgCdTe dark current and noise initiated by the SNAP detector research and development program makes it the baseline detector technology for SNAP. However, the results presented herein suggest that existing InGaAs technology is a suitable alternative for other future astronomy applications.

  5. The Chara Array Angular Diameter of HR 8799 Favors Planetary Masses for Its Imaged Companions

    Science.gov (United States)

    2012-12-10

    Department of Physics & Astronomy, Macquarie University, New South Wales, NSW 2109, Australia 5 NASA Exoplanet Science Institute, California Institute of...effect would evaporate any surface water while the outer boundary is the limit where a cloudless atmosphere could maintain a surface temperature of 273 K...would be on the exoplanet /brown dwarf cusp. We thank Gerard van Belle for his insight on the nature of HR 8799’s pirouette through space. The CHARA Array

  6. Transmission Raman Measurements Using a Spatial Heterodyne Raman Spectrometer (SHRS).

    Science.gov (United States)

    Strange, K Alicia; Paul, Kelly C; Angel, S Michael

    2017-02-01

    A spatial heterodyne Raman spectrometer (SHRS) was used to measure transmission Raman spectra of highly scattering compounds. Transmission Raman spectral intensities of ibuprofen were only 2.4 times lower in intensity than backscatter Raman spectra. The throughput was about eight times higher than an f/1.8 dispersive spectrometer, and the width of the area viewed was found to be seven to nine times higher, using 50.8 mm and 250 mm focal length collection lenses. However, the signal-to-noise (S/N) ratio was two times lower for the SHRS than the f/1.8 dispersive spectrometer, apparently due to high levels of stray light.

  7. Self Referencing Heterodyne Transient Grating Spectroscopy with Short Wavelength

    Directory of Open Access Journals (Sweden)

    Jakob Grilj

    2015-04-01

    Full Text Available Heterodyning by a phase stable reference electric field is a well known technique to amplify weak nonlinear signals. For short wavelength, the generation of a reference field in front of the sample is challenging because of a lack of suitable beamsplitters. Here, we use a permanent grating which matches the line spacing of the transient grating for the creation of a phase stable reference field. The relative phase among the two can be changed by a relative translation of the permanent and transient gratings in direction orthogonal to the grating lines. We demonstrate the technique for a transient grating on a VO2 thin film and observe constructive as well as destructive interference signals.

  8. Heterodyne x-ray diffuse scattering from coherent phonons.

    Science.gov (United States)

    Kozina, M; Trigo, M; Chollet, M; Clark, J N; Glownia, J M; Gossard, A C; Henighan, T; Jiang, M P; Lu, H; Majumdar, A; Zhu, D; Reis, D A

    2017-09-01

    Here, we report Fourier-transform inelastic x-ray scattering measurements of photoexcited GaAs with embedded ErAs nanoparticles. We observe temporal oscillations in the x-ray scattering intensity, which we attribute to inelastic scattering from coherent acoustic phonons. Unlike in thermal equilibrium, where inelastic x-ray scattering is proportional to the phonon occupation, we show that the scattering is proportional to the phonon amplitude for coherent states. The wavevectors of the observed phonons extend beyond the excitation wavevector. The nanoparticles break the discrete translational symmetry of the lattice, enabling the generation of large wavevector coherent phonons. Elastic scattering of x-ray photons from the nanoparticles provides a reference for heterodyne mixing, yielding signals proportional to the phonon amplitude.

  9. Heterodyne interferometric system with subnanometer accuracy for measurement of straightness.

    Science.gov (United States)

    Wu, Chien-Ming

    2004-07-01

    A generalized laser interferometer system based on three design principles, i.e., heterodyne frequency, prevention of mixing, and perfect symmetry, is described. These design principles give rise to an interferometer in a highly stable system with no periodic nonlinearity. A novel straightness sensor, consisting of a straightness prism and a straightness reflector, is incorporated into the generalized system to form a straightness interferometer. A Hewlett-Packard commercial linear interferometer was used to validate the interferometer's parameters. Based on the present design, the interferometer has a gain of 0.348, a periodic nonlinearity of less than 40 pm, and a displacement noise of 12 pm/mean square root of Hz at a bandwidth of 7.8 kHz. This system is useful for precision straightness measurements.

  10. Phosphor-filled micro-well arrays for digital x-ray imaging: effects of surface treatments

    Science.gov (United States)

    Yun, Seungman; Lim, Chang Hwy; Kim, Tae Woo; Cunningham, Ian; Achterkirchen, Thorsten; Kim, Ho Kyung

    2010-04-01

    We are developing pixel-structured scintillators for the eventual purpose of high-resolution and high-sensitivity x-ray imaging applications. The pixel-structured scintillators were fabricated by filling Gd2O2S:Tb phosphor powder into the silicon micro-well arrays by using a simple sedimentation method. The micro-well arrays having a depth of 180 μm were fabricated by deep reactive ion etching of silicon wafers. To enhance the optical gain and the Swank noise factor, we applied reflectance at the inside wall surfaces. Two different inside-surface treatments were applied; 0.2-μm-thick titanium which has 70% reflectance and 1-μm-thick silicon dioxide which was grown by thermal oxidation. The imaging performance was evaluated in terms of modulation-transfer function (MTF), noise-power spectrum (NPS), and detective quantum efficiency (DQE). Compared with the commercial phosphor screen as a reference, much enhanced MTF results were measured. However, very low values of the system gain due to trapping of the generated optical photons at the wall surfaces give rise to the poorer DQE performance rather than that of the reference detector. The theoretical cascaded model analysis estimates much improved DQE performances with improved design parameters, such as higher reflectance of 90% at the wall surfaces.

  11. SU-C-201-05: Silicon Array Dosimeter in Situ with Electronic Portal Image Device for Simultaneous Transit Dose and Image Verification in Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Deshpande, S [Liverpool and Macarthur cancer therapy centre, Liverpool, NSW (United Kingdom); Alhujaili, S [University of Wollongong, Wollongong, Wollongong, NSW (Australia); Vial, P [Liverpool Hospital, Sydney, NSW (Australia); Holloway, L [Liverpool Hospital & Ingham Institute, Liverpool, NSW (United Kingdom); Petasecca, M; Rozenfeld, A [University of Wollongong, Wollongong, NSW (Australia); Metcalfe, P [University of Wollongong, Wollongong, NSW (Australia)

    2016-06-15

    Purpose: To investigate an Electronic Portal Imaging Device (EPID) coupled to a 2D array dosimeter to provide simultaneous imaging and dose verification. Methods: The novel dual detector configuration comprised of a 2D diode array dosimeter, referred to as a Magic Plate (MP) placed directly on a standard EPID. Dose response of the MP was evaluated by measuring the detector’s response with respect to off-axis position and field size with 30 cm of solid water (SW) acting as a transit object in the beam. Measurements were performed with 3, 5, 10 and 15 mm SW build-up and compared to 2D ionisation chamber array (ICA) measurements and the PinnacleTM treatment planning system (TPS) at a source to detector distance of 150 cm with a 6 MV beam. Clinical dosimetric performance was evaluated by measuring a number of intensity-modulated radiation therapy (IMRT) beams in transit geometry. Imaging performance of the EPID was quantified by measuring the contrast-to-noise ratio (CNR) and spatial resolution. Images of a Rando phantom were used for qualitative assessment. Results: Measured MP off-axis and field size response agreed within 2% of TPS and ICA responses when measured using 15 mm SW build-up. Clinical IMRT beams had gamma pass rates of ≥95% at 3%/3mm criteria. Measured CNR and spatial resolution (f50) were 264.96, 210.6, and 0.41, 0.40 with build-up of 5 and 15 mm respectively for the dual detector configuration. CNR and spatial resolution of 643.9 and 0.41 were measured for standard EPID. CNR was quantitatively worse in the dual detector configuration. Differences in imaging performance were not visible in a qualitative assessment using a Rando phantom. Conclusion: Combining a prototype MP 2D dosimeter with a conventional EPID did not significantly detract from the performance of either device and has the potential for simultaneous on-line patient transit dosimetry and image assessment in radiation therapy. Cancer Institute NSW Australia(Research Equipment Grant 10

  12. HARDWARE REALIZATION OF CANNY EDGE DETECTION ALGORITHM FOR UNDERWATER IMAGE SEGMENTATION USING FIELD PROGRAMMABLE GATE ARRAYS

    Directory of Open Access Journals (Sweden)

    ALEX RAJ S. M.

    2017-09-01

    Full Text Available Underwater images raise new challenges in the field of digital image processing technology in recent years because of its widespread applications. There are many tangled matters to be considered in processing of images collected from water medium due to the adverse effects imposed by the environment itself. Image segmentation is preferred as basal stage of many digital image processing techniques which distinguish multiple segments in an image and reveal the hidden crucial information required for a peculiar application. There are so many general purpose algorithms and techniques that have been developed for image segmentation. Discontinuity based segmentation are most promising approach for image segmentation, in which Canny Edge detection based segmentation is more preferred for its high level of noise immunity and ability to tackle underwater environment. Since dealing with real time underwater image segmentation algorithm, which is computationally complex enough, an efficient hardware implementation is to be considered. The FPGA based realization of the referred segmentation algorithm is presented in this paper.

  13. Multistatic Array Sampling Scheme for Fast Near-Field Image Reconstruction

    Science.gov (United States)

    2016-01-01

    frequency response of the scene is sampled on a regularly spaced two-dimensional grid. Following collection of all measurements, the image can be...images were formed with 18-26.5 GHz stimulus , using 160 frequency points. The 3D images were realized with 21 depth slices, spaced by 0.015m. Fig. 7...McMakin, and T. E. Hall, “Three-dimensional millimeter-wave imaging for concealed weapon detection,” IEEE Trans- actions on Microwave Theory and

  14. A Monolithic, Non-Field-Widened Spatial Heterodyne Spectrometer for Solar System Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of this project is to produce a monolithic Spatial Heterodyne Spectrometer (a Fourier Transform Interferometer) for use in Solar System exploration. In...

  15. Non-intrusive, high-resolution, real-time, two-dimensional imaging of multiphase materials using acoustic array sensors

    Science.gov (United States)

    Cassiède, M.; Shaw, J. M.

    2015-04-01

    Two parallel multi-element ultrasonic acoustic arrays combined with sets of focal laws for acoustic signal generation and a classical tomographic inversion algorithm are used to generate real-time two-dimensional micro seismic acoustic images of multiphase materials. Proof of concept and calibration measurements were performed for single phase and two phase liquids, uniform polyvinyl chloride (PVC) plates, and aluminum cylinders imbedded in PVC plates. Measurement artefacts, arising from the limited range of viewing angles, and the compromise between data acquisition rate and image quality are discussed. The angle range of scanning and the image resolution were varied, and the effects on the quality of the reproduction of the speed of sound profiles of model solids and liquids with known geometries and compositions were analysed in detail. The best image quality results were obtained for a scanning angle range of [-35°, 35°] at a step size of 2.5° post processed to generate images on a 40 μm square grid. The data acquisition time for high quality images with a 30 mm × 40 mm view field is 10 min. Representation of two-phase solids with large differences in speed of sound between phases and where one phase is dispersed in the form of macroscopic objects (greater than 1 mm in diameter) proved to be the most difficult to image accurately. Liquid-liquid and liquid-vapor phase boundaries, in micro porous solids by contrast, were more readily defined. Displacement of air by water and water by heptane in natural porous limestone provides illustrative kinetic examples. Measurement results with these realistic cases demonstrate the feasibility of the technique to monitor in real time and on the micrometer length scale local composition and flow of organic liquids in inorganic porous media, one of many envisioned engineering applications. Improvement of data acquisition rate is an area for future collaborative study.

  16. Focal Plane Array Concept and Technologies for the X-Ray Microcalorimeter Spectrometer on the Advanced X-ray Spectroscopic Imaging Observatory (AXSIO)

    Science.gov (United States)

    Bandler, Simon; Adams, J. D.; Busch, S. E.; Chervenak, J. A.; Eckart, M. E.; Finkbeiner, F. M.; Kilbourne, C.; Lee, S.; Porter, F. S.; Porst, J.; Sadleir, J. E.; Smith, S. J.; Doriese, W. B.; Fowler, J. W.; Hilton, G. C.; Irwin, K.; Reintsema, C. D.; Ullom, J. N.

    2013-04-01

    We are developing large-format arrays of x-ray microcalorimeters to enable high-resolution, imaging X-ray imaging spectroscopy that meet the needs of the AXSIO mission. This mission requires microcalorimeter focal plane with an overall field of view of of 4x4 arcmin and an energy resolution of better then 3 eV (or, a spectral resolving power of > 2000 at 6 keV) over part of the array. To achieve this, we are developing technologies to implement an overall array that consists of three components: a small, central inner array with very small pixels to purposely over-sample the x-ray beam to provide high spectral resolution (strategy to use these technologies to design the microcalorimeter instrument for AXSIO with optimal performance and engineering margin.

  17. Characterization of the effective performance of a high-frequency annular-array based imaging system using anechoic-pipe phantoms

    Science.gov (United States)

    Filoux, Erwan; Mamou, Jonathan; Moran, Carmel M.; Pye, Stephen D.; Ketterling, Jeffrey A.

    2012-01-01

    A resolution integral (RI) method based on anechoic-pipe, tissue-mimicking phantoms was used to compare the detection capabilities of high-frequency imaging systems based on a single-element transducer, a state-of-the-art, 256-element linear array or a 5-element annular array. All transducers had a central frequency of 40 MHz with similar conventionally measured axial and lateral resolutions (about 50 and 85 μm, respectively). Using the RI metric, the annular array achieved the highest performance (RI = 60), followed by the linear array (47) and the single-element transducer (24). Results showed that the RI metric could be used to efficiently quantify the effective transducer performance and compare the image quality of different systems. PMID:23221233

  18. Correspondence - Characterization of the effective performance of a high-frequency annular-array-based imaging system using anechoic-pipe phantoms.

    Science.gov (United States)

    Filoux, Erwan; Mamou, Jonathan; Moran, Carmel M; Pye, Stephen D; Ketterling, Jeffrey A

    2012-12-01

    A resolution integral (RI) method based on anechoic- pipe, tissue-mimicking phantoms was used to compare the detection capabilities of high-frequency imaging systems based on a single-element transducer, a state-of-the-art 256-element linear array, or a 5-element annular array. All transducers had a central frequency of 40 MHz with similar conventionally measured axial and lateral resolutions (about 50 and 85 μm, respectively). Using the RI metric, the annular array achieved the highest performance (RI = 60), followed by the linear array (RI = 47), and the single-element transducer (RI = 24). Results showed that the RI metric could be used to efficiently quantify the effective transducer performance and compare the image quality of different systems.

  19. Development of outdoor luminescence imaging for drone-based PV array inspection

    DEFF Research Database (Denmark)

    Benatto, Gisele Alves dos Reis; Thorsteinsson, Sune; Riedel, Nicholas

    2017-01-01

    This work has the goal to perform outdoor defect detection imaging that will be used in a fast, accurate and automatic drone-based survey system for PV power plants. The imaging development focuses on techniques that do not require electrical contact, permitting automatic drone inspections...

  20. Development of outdoor luminescence imaging for drone-based PV array inspection

    DEFF Research Database (Denmark)

    Benatto, Gisele Alves dos Reis; Thorsteinsson, Sune; Riedel, Nicholas

    2017-01-01

    This work has the goal to perform outdoor defect detection imaging that will be used in a fast, accurate and automatic drone-based survey system for PV power plants. The imaging development focuses on techniques that do not require electrical contact, permitting automatic drone inspections...... new perspective in large-scale PV inspection....

  1. Improving performance of a CdZnTe imaging array by mapping the detector with gamma rays

    CERN Document Server

    Marks, D G; Barrett, H H; Tüller, J; Woolfenden, J M

    1999-01-01

    We can greatly reduce image artifacts in our pixellated CdZnTe arrays by mapping imperfect regions with a narrow collimated beam of gamma rays. Portions of our detectors produce signals that agree well with simulations of gamma-ray interactions, but there are many examples of structures in the material that respond unpredictably to gamma rays. We mapped some of these imperfect regions using 60 and 140 keV gamma-ray beams, recording a 7x7 set of pixel signals for each interaction. The pixel pitch was 380 mu m. We used the mapped data to estimate the probability density function (PDF) of the pixel signals for each interaction position. Images were taken on the mapped sections, storing each gamma ray as a list of pixel signals. Images could be formed by either estimating each gamma-ray interaction position individually or using the entire set of image data in a single iterative computation using the expectation-maximization (EM) algorithm. At 60 keV individual interaction positions were estimated by fitting the ...

  2. Comparison of Vector Velocity Imaging using Directional Beamforming and Transverse Oscillation for a Convex Array Transducer

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2014-01-01

    been acquired using the SARUS experimental ultrasound scanner connected to a BK 8820e (BK Medical, Herlev, Denmark) convex array probe with 192 active elements. A duplex sequence with 129 B-mode emissions interleaved with 129 flow emissions has been made. The flow was generated in a recirculating flow...... rig with a stationary, laminar flow, and the volume flow was measured by a MAG 3000 (Danfos, Sønderbog, Denmark) magnetic flow meter for reference. Data were beamformed with an optimized transverse oscillation scheme for the TO VFI, and standard fourth-order estimators were employed for the velocity...

  3. Large-Format AlGaN PIN Photodiode Arrays for UV Images

    Science.gov (United States)

    Aslam, Shahid; Franz, David

    2010-01-01

    A large-format hybridized AlGaN photodiode array with an adjustable bandwidth features stray-light control, ultralow dark-current noise to reduce cooling requirements, and much higher radiation tolerance than previous technologies. This technology reduces the size, mass, power, and cost of future ultraviolet (UV) detection instruments by using lightweight, low-voltage AlGaN detectors in a hybrid detector/multiplexer configuration. The solar-blind feature eliminates the need for additional visible light rejection and reduces the sensitivity of the system to stray light that can contaminate observations.

  4. The Application of Seismic Array Techniques to Image UXO-Contaminated Littoral Environments

    Science.gov (United States)

    Gritto, R.; Korneev, V.; Nihei, K.; Johnson, L.

    2004-12-01

    We investigate the application of seismic array techniques to increase the energy radiation and resolution of seismic waves in littoral areas to improve the success rate of detecting UXO in contaminated underwater sites. The investigation is carried out based on numerical modeling, including 2-D finite difference modeling and 3-D analytical solutions of the problem. In addition to various UXO orientations, we also modeled the presence of clutter in the subsurface. An array of 31 source and receiver elements was located floating in the water as well as sited on the seafloor, which allowed the comparison between single source-receiver combinations and beam-forming techniques. The numerical forward modeling involved noise-free and noisy data as well as interferences by free surface reflections (off the water-air interface), which produced the strongest phases on the seismograms. The inversion of the scattered seismic energy was performed using a 2-D eikonal solver (curved rays), which stacked and located the recorded amplitudes in space to determine the location of the UXO. The inversion also included the determination of the best fitting velocity model for the bay mud. The results of the 2-D modeling indicated that a single, horizontally oriented, UXO could be well detected as a function of depth and horizontal location. In the case of the source-receiver array being placed on the seafloor, the edges of the UXO were resolved indicating its horizontal extent, while the top of the UXO was correctly located. The cases of a second, vertically oriented, UXO and clutter located 0.1 m next to the first UXO, produced similar results. In each case the two objects produced slight interference in the backscattered seismic signal, yet the resolution of the seismic wave was still good enough to resolve the two objects from each other. The introduction of a rippled water-seafloor interface during the forward modeling didn't change the results for the case of a floating source

  5. Structure of multiphoton quantum optics. II. Bipartite systems, physical processes, and heterodyne squeezed states

    Science.gov (United States)

    dell'Anno, Fabio; de Siena, Silvio; Illuminati, Fabrizio

    2004-03-01

    Extending the scheme developed for a single mode of the electromagnetic field in the preceding paper [F. Dell’Anno, S. De Siena, and F. Illuminati, Phys. Rev. A 69, 033812 (2004)], we introduce two-mode nonlinear canonical transformations depending on two heterodyne mixing angles. They are defined in terms of Hermitian nonlinear functions that realize heterodyne superpositions of conjugate quadratures of bipartite systems. The canonical transformations diagonalize a class of Hamiltonians describing nondegenerate and degenerate multiphoton processes. We determine the coherent states associated with the canonical transformations, which generalize the nondegenerate two-photon squeezed states. Such heterodyne multiphoton squeezed states are defined as the simultaneous eigenstates of the transformed, coupled annihilation operators. They are generated by nonlinear unitary evolutions acting on two-mode squeezed states. They are non-Gaussian, highly nonclassical, entangled states. For a quadratic nonlinearity the heterodyne multiphoton squeezed states define two-mode cubic phase states. The statistical properties of these states can be widely adjusted by tuning the heterodyne mixing angles, the phases of the nonlinear couplings, as well as the strength of the nonlinearity. For quadratic nonlinearity, we study the higher-order contributions to the susceptibility in nonlinear media and we suggest possible experimental realizations of multiphoton conversion processes generating the cubic-phase heterodyne squeezed states.

  6. A twenty-eight channel coil array for improved optic nerve imaging

    Science.gov (United States)

    Merrill, Robb Phillip

    The purpose of this work was to design and construct a radio-frequency coil optimized for imaging the Optic Nerve (ON) on a Siemens 3T magnetic resonance imaging (MRI) scanner. The specific goals were to optimize signal sensitivity from the orbit to the optic chiasm and improve SNR over designs currently in use. The constructed coil features two fiberglass formers that can slide over each other to accommodate any arbitrary head size, while maintaining close coupling near the eyes and around the head in general. This design eliminates the air void regions that occur between the coil elements and the forehead when smaller heads are imaged in one-piece, nonadjustable coil formers. The 28 coil elements were placed using a soccer-ball pattern layout to maximize head coverage. rSNR profiles from phantom imaging studies show that the ON coil provides approximately 55% greater rSNR at the region of the optic chiasm and approximately 400% near the orbits compared to the 12-channel commercial coil. The improved rSNR in the optic nerve region allows performance of high resolution DTI, which provides a qualitative measurement for evaluating optic neuritis. Images from volunteer and patient studies with the ON coil reveal plaques that correspond well with the patient disease history of chronic bilateral optic neuritis. Correspondence of image findings with patient disease histories demonstrates that optic neuritis can be visualized and detected in patients using 3T MRI with advanced imaging coils, providing improved patient care.

  7. Dense-array concentrator photovoltaic system using non-imaging dish concentrator and crossed compound parabolic concentrator

    Science.gov (United States)

    Chong, Kok-Keong; Yew, Tiong-Keat; Wong, Chee-Woon; Tan, Ming-Hui; Tan, Woei-Chong; Lai, An-Chow; Lim, Boon-Han; Lau, Sing-Liong; Rahman, Faidz Abdul

    2015-04-01

    Solar concentrating device plays an important role by making use of optical technology in the design, which can be either reflector or lens to deliver high flux of sunlight onto the Concentrator Photovoltaic (CPV) module receiver ranging from hundreds to thousand suns. To be more competitive compared with fossil fuel, the current CPV systems using Fresnel lens and Parabolic dish as solar concentrator that are widely deployed in United States, Australia and Europe are facing great challenge to produce uniformly focused sunlight on the solar cells as to reduce the cost of electrical power generation. The concept of non-imaging optics is not new, but it has not fully explored by the researchers over the world especially in solving the problem of high concentration solar energy, which application is only limited to be a secondary focusing device or low concentration device using Compound Parabolic Concentrator. With the current advancement in the computer processing power, we has successfully invented the non-imaging dish concentrator (NIDC) using numerical simulation method to replace the current parabolic dish as primary focusing device with high solar concentration ratio (more than 400 suns) and large collective area (from 25 to 125 m2). In this paper, we disclose our research and development on dense array CPV system based on non-imaging optics. The geometry of the NIDC is determined using a special computational method. In addition, an array of secondary concentrators, namely crossed compound parabolic concentrators, is also proposed to further focus the concentrated sunlight by the NIDC onto active area of solar cells of the concentrator photovoltaic receiver. The invention maximizes the absorption of concentrated sunlight for the electric power generation system.

  8. In vivo multiphoton imaging of a diverse array of fluorophores to investigate deep neurovascular structure.

    Science.gov (United States)

    Miller, David R; Hassan, Ahmed M; Jarrett, Jeremy W; Medina, Flor A; Perillo, Evan P; Hagan, Kristen; Shams Kazmi, S M; Clark, Taylor A; Sullender, Colin T; Jones, Theresa A; Zemelman, Boris V; Dunn, Andrew K

    2017-07-01

    We perform high-resolution, non-invasive, in vivo deep-tissue imaging of the mouse neocortex using multiphoton microscopy with a high repetition rate optical parametric amplifier laser source tunable between λ=1,100 and 1,400 nm. By combining the high repetition rate (511 kHz) and high pulse energy (400 nJ) of our amplifier laser system, we demonstrate imaging of vasculature labeled with Texas Red and Indocyanine Green, and neurons expressing tdTomato and yellow fluorescent protein. We measure the blood flow speed of a single capillary at a depth of 1.2 mm, and image vasculature to a depth of 1.53 mm with fine axial steps (5 μm) and reasonable acquisition times. The high image quality enabled analysis of vascular morphology at depths to 1.45 mm.

  9. Image processing system architecture using parallel arrays of digital signal processors

    Science.gov (United States)

    Kshirsagar, Shirish P.; Hobson, Clifford A.; Hartley, David A.; Harvey, David M.

    1993-10-01

    The paper describes the requirements of a high definition, high speed image processing system. Different types of parallel architectures were considered for the system. Advantages and limitations of SIMD and MIMD architectures are briefly discussed for image processing applications. A parallel image processing system based on MIMD architecture has been developed using multiple digital signal processors which can communicate with each other through an interconnection network. Texas Instruments TMS320C40 digital signal processors have been selected because they have a powerful floating point CPU supported by fast parallel communication ports, a DMA coprocessor and two memory interfaces. A five processor system is described in the paper. The EISA bus is used as the host interface and VISION bus is used to transfer images between the processors. The system is being used for automated non-contact inspection in which electro-optic signals are processed to identify manufacturing problems.

  10. Three-dimensional integral imaging displays using a quick-response encoded elemental image array: an overview

    Science.gov (United States)

    Markman, A.; Javidi, B.

    2016-06-01

    Quick-response (QR) codes are barcodes that can store information such as numeric data and hyperlinks. The QR code can be scanned using a QR code reader, such as those built into smartphone devices, revealing the information stored in the code. Moreover, the QR code is robust to noise, rotation, and illumination when scanning due to error correction built in the QR code design. Integral imaging is an imaging technique used to generate a three-dimensional (3D) scene by combining the information from two-dimensional (2D) elemental images (EIs) each with a different perspective of a scene. Transferring these 2D images in a secure manner can be difficult. In this work, we overview two methods to store and encrypt EIs in multiple QR codes. The first method uses run-length encoding with Huffman coding and the double-random-phase encryption (DRPE) to compress and encrypt an EI. This information is then stored in a QR code. An alternative compression scheme is to perform photon-counting on the EI prior to compression. Photon-counting is a non-linear transformation of data that creates redundant information thus improving image compression. The compressed data is encrypted using the DRPE. Once information is stored in the QR codes, it is scanned using a smartphone device. The information scanned is decompressed and decrypted and an EI is recovered. Once all EIs have been recovered, a 3D optical reconstruction is generated.

  11. Development of outdoor luminescence imaging for drone-based PV array inspection

    DEFF Research Database (Denmark)

    Benatto, Gisele Alves dos Reis; Riedel, Nicholas; Thorsteinsson, Sune

    This work has the goal to examined experimentally PV module imaging methods under natural light conditions, that will be used in a fast, accurate and automatic drone-based inspection system for PV power plants.......This work has the goal to examined experimentally PV module imaging methods under natural light conditions, that will be used in a fast, accurate and automatic drone-based inspection system for PV power plants....

  12. Real time imaging analysis using a terahertz quantum cascade laser and a microbolometer focal plane array

    OpenAIRE

    Buchanan, Kevin William.

    2008-01-01

    It is widely published that the terahertz (THz) spectral range has potential for imaging in the fields of military and security applications. The Sensors Research Laboratory previously achieved real-time imaging of concealed objects using a 1mW quantum cascade laser (QCL) and an uncooled vanadium oxide/silicon nitride based microbolometer. This thesis introduces an amorphous silicon based microbolometer with improved NETD in the 8-12 micrometer infrared spectral range. The QCL is usually oper...

  13. Double Stage Delay Multiply and Sum Beamforming Algorithm: Application to Linear-Array Photoacoustic Imaging.

    Science.gov (United States)

    Mozaffarzadeh, Moein; Mahloojifar, Ali; Orooji, Mahdi; Adabi, Saba; Nasiriavanaki, Mohammadreza

    2017-04-05

    Photoacoustic imaging (PAI) is an emerging medical imaging modality capable of providing high spatial resolution of Ultrasound (US) imaging and high contrast of optical imaging. Delay-and-Sum (DAS) is the most common beamforming algorithm in PAI. However, using DAS beamformer leads to low resolution images and considerable contribution of offaxis signals. A new paradigm namely Delay-Multiply-and-Sum (DMAS), which was originally used as a reconstruction algorithm in confocal microwave imaging, was introduced to overcome the challenges in DAS. DMAS was used in PAI systems and it was shown that this algorithm results in resolution improvement and sidelobe degrading. However, DMAS is still sensitive to high levels of noise, and resolution improvement is not satisfying. Here, we propose a novel algorithm based on DAS algebra inside DMAS formula expansion, Double Stage DMAS (DSDMAS), which improves the image resolution and levels of sidelobe, and is much less sensitive to high level of noise compared to DMAS. The performance of DS-DMAS algorithm is evaluated numerically and experimentally. The resulted images are evaluated qualitatively and quantitatively using established quality metrics including signal-to-noise ratio (SNR), full-widthhalf- maximum (FWHM) and contrast ratio (CR). It is shown that DS-DMAS outperforms DAS and DMAS at the expense of higher computational load. DS-DMAS reduces the lateral valley for about 15 dB and improves the SNR and FWHM better than 13% and 30%, respectively. Moreover, the levels of sidelobe are reduced for about 10 dB in comparison with those in DMAS.

  14. CHIMPS: the 13CO/C18O (J = 3 → 2) Heterodyne Inner Milky Way Plane Survey

    Science.gov (United States)

    Rigby, A. J.; Moore, T. J. T.; Plume, R.; Eden, D. J.; Urquhart, J. S.; Thompson, M. A.; Mottram, J. C.; Brunt, C. M.; Butner, H. M.; Dempsey, J. T.; Gibson, S. J.; Hatchell, J.; Jenness, T.; Kuno, N.; Longmore, S. N.; Morgan, L. K.; Polychroni, D.; Thomas, H.; White, G. J.; Zhu, M.

    2016-03-01

    We present the 13CO/C18O (J = 3 → 2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) which has been carried out using the Heterodyne Array Receiver Program on the 15 m James Clerk Maxwell Telescope (JCMT) in Hawaii. The high-resolution spectral survey currently covers |b| ≤ 0.5° and 28° ≲ l ≲ 46°, with an angular resolution of 15 arcsec in 0.5 km s-1 velocity channels. The spectra have a median rms of ˜0.6 K at this resolution, and for optically thin gas at an excitation temperature of 10 K, this sensitivity corresponds to column densities of NH2 ˜ 3 × 1020 cm-2 and NH2 ˜ 4 × 1021 cm-2 for 13CO and C18O, respectively. The molecular gas that CHIMPS traces is at higher column densities and is also more optically thin than in other publicly available CO surveys due to its rarer isotopologues, and thus more representative of the three-dimensional structure of the clouds. The critical density of the J = 3 → 2 transition of CO is ≳104 cm-3 at temperatures of ≤20 K, and so the higher density gas associated with star formation is well traced. These data complement other existing Galactic plane surveys, especially the JCMT Galactic Plane Survey which has similar spatial resolution and column density sensitivity, and the Herschel infrared Galactic Plane Survey. In this paper, we discuss the observations, data reduction and characteristics of the survey, presenting integrated-emission maps for the region covered. Position-velocity diagrams allow comparison with Galactic structure models of the Milky Way, and while we find good agreement with a particular four-arm model, there are some significant deviations.

  15. Implementation of a multi-spectral color imaging device without color filter array

    Science.gov (United States)

    Langfelder, G.; Longoni, A. F.; Zaraga, F.

    2011-01-01

    In this work the use of the Transverse Field Detector (TFD) as a device for multispectral image acquisition is proposed. The TFD is a color imaging pixel capable of color reconstruction without color filters. Its basic working principle is based on the generation of a suitable electric field configuration inside a Silicon depleted region by means of biasing voltages applied to surface contacts. With respect to previously proposed methods for performing multispectral capture, the TFD has a unique characteristic of electrically tunable spectral responses. This feature allows capturing an image with different sets of spectral responses (RGB, R'G'B', and so on) simply by tuning the device biasing voltages in multiple captures. In this way no hardware complexity (no external filter wheels or varying sources) is added with respect to a colorimetric device. The estimation of the spectral reflectance of the area imaged by a TFD pixel is based in this work on a linear combination of six eigenfunctions. It is shown that a spectral reconstruction can be obtained either (1) using two subsequent image captures that generate six TFD spectral responses or (2) using a new asymmetric biasing scheme, which allows the implementation of five spectral responses for each TFD pixel site in a single configuration, definitely allowing one-shot multispectral imaging.

  16. Theoretical investigation of the noise performance of active pixel imaging arrays based on polycrystalline silicon thin film transistors.

    Science.gov (United States)

    Koniczek, Martin; Antonuk, Larry E; El-Mohri, Youcef; Liang, Albert K; Zhao, Qihua

    2017-07-01

    Active matrix flat-panel imagers, which typically incorporate a pixelated array with one a-Si:H thin-film transistor (TFT) per pixel, have become ubiquitous by virtue of many advantages, including large monolithic construction, radiation tolerance, and high DQE. However, at low exposures such as those encountered in fluoroscopy, digital breast tomosynthesis and breast computed tomography, DQE is degraded due to the modest average signal generated per interacting x-ray relative to electronic additive noise levels of ~1000 e, or greater. A promising strategy for overcoming this limitation is to introduce an amplifier into each pixel, referred to as the active pixel (AP) concept. Such circuits provide in-pixel amplification prior to readout as well as facilitate correlated multiple sampling, enhancing signal-to-noise and restoring DQE at low exposures. In this study, a methodology for theoretically investigating the signal and noise performance of imaging array designs is introduced and applied to the case of AP circuits based on low-temperature polycrystalline silicon (poly-Si), a semiconductor suited to manufacture of large area, radiation tolerant arrays. Computer simulations employing an analog circuit simulator and performed in the temporal domain were used to investigate signal characteristics and major sources of electronic additive noise for various pixel amplifier designs. The noise sources include photodiode shot noise and resistor thermal noise, as well as TFT thermal and flicker noise. TFT signal behavior and flicker noise were parameterized from fits to measurements performed on individual poly-Si test TFTs. The performance of three single-stage and three two-stage pixel amplifier designs were investigated under conditions relevant to fluoroscopy. The study assumes a 20 × 20 cm 2 , 150 μm pitch array operated at 30 fps and coupled to a CsI:Tl x-ray converter. Noise simulations were performed as a function of operating conditions, including

  17. Computationally rapid method of estimating signal-to-noise ratio for phased array image reconstructions.

    Science.gov (United States)

    Wiens, Curtis N; Kisch, Shawn J; Willig-Onwuachi, Jacob D; McKenzie, Charles A

    2011-10-01

    Measuring signal-to-noise ratio (SNR) for parallel MRI reconstructions is difficult due to spatially dependent noise amplification. Existing approaches for measuring parallel MRI SNR are limited because they are not applicable to all reconstructions, require significant computation time, or rely on repeated image acquisitions. A new SNR estimation approach is proposed, a hybrid of the repeated image acquisitions method detailed in the National Electrical Manufacturers Association (NEMA) standard and the Monte Carlo based pseudo-multiple replica method, in which the difference between images reconstructed from the unaltered acquired data and that same data reconstructed after the addition of calibrated pseudo-noise is used to estimate the noise in the parallel MRI image reconstruction. This new noise estimation method can be used to rapidly compute the pixel-wise SNR of the image generated from any parallel MRI reconstruction of a single acquisition. SNR maps calculated with the new method are validated against existing SNR calculation techniques. Copyright © 2011 Wiley-Liss, Inc.

  18. Identification and Quantification of Microplastics in Wastewater Using Focal Plane Array-Based Reflectance Micro-FT-IR Imaging.

    Science.gov (United States)

    Tagg, Alexander S; Sapp, Melanie; Harrison, Jesse P; Ojeda, Jesús J

    2015-06-16

    Microplastics (microplastics in these matrices has not been investigated. Although efficient methods for the analysis of microplastics in sediment samples and marine organisms have been published, no methods have been developed for detecting these pollutants within organic-rich wastewater samples. In addition, there is no standardized method for analyzing microplastics isolated from environmental samples. In many cases, part of the identification protocol relies on visual selection before analysis, which is open to bias. In order to address this, a new method for the analysis of microplastics in wastewater was developed. A pretreatment step using 30% hydrogen peroxide (H2O2) was employed to remove biogenic material, and focal plane array (FPA)-based reflectance micro-Fourier-transform (FT-IR) imaging was shown to successfully image and identify different microplastic types (polyethylene, polypropylene, nylon-6, polyvinyl chloride, polystyrene). Microplastic-spiked wastewater samples were used to validate the methodology, resulting in a robust protocol which was nonselective and reproducible (the overall success identification rate was 98.33%). The use of FPA-based micro-FT-IR spectroscopy also provides a considerable reduction in analysis time compared with previous methods, since samples that could take several days to be mapped using a single-element detector can now be imaged in less than 9 h (circular filter with a diameter of 47 mm). This method for identifying and quantifying microplastics in wastewater is likely to provide an essential tool for further research into the pathways by which microplastics enter the environment.

  19. Inspection of copper canisters for spent nuclear fuel by means of ultrasound. Phased arrays, ultrasonic imaging and nonlinear acoustics

    Energy Technology Data Exchange (ETDEWEB)

    Stepinski, Tadeusz (ed.); Ping Wu; Wennerstroem, Erik [Uppsala Univ. (Sweden). Signals and Systems

    2004-09-01

    This report contains the research results concerning advanced ultrasound for the inspection of copper canisters for spent nuclear fuel obtained at Signals and Systems, Uppsala University in years 2003/2004. After a short introduction a review of beam forming fundamentals required for proper understanding phased array operation is included. The factors that determine lateral resolution during ultrasonic imaging of flaws in solids are analyzed and results of simulations modelling contact inspection of copper are presented. In the second chapter an improved synthetic aperture imaging (SAI) technique is introduced. The proposed SAI technique is characterized by an enhanced lateral resolution compared with the previously proposed extended synthetic aperture focusing technique (ESAFT). The enhancement of imaging performance is achieved due to more realistic assumption concerning the probability density function of scatterers in the region of interest. The proposed technique takes the form of a two-step algorithm using the result obtained in the first step as a prior for the second step. Final chapter contains summary of our recent experimental and theoretical research on nonlinear ultrasonics of unbounded interfaces. A new theoretical model for rough interfaces is developed, and the experimental results from the copper specimens that mimic contact cracks of different types are presented. Derivation of the theory and selected measurement results are given in appendix.

  20. Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): High-Resolution Interferometric Imaging

    Science.gov (United States)

    Shimojo, M.; Bastian, T. S.; Hales, A. S.; White, S. M.; Iwai, K.; Hills, R. E.; Hirota, A.; Phillips, N. M.; Sawada, T.; Yagoubov, P.; Siringo, G.; Asayama, S.; Sugimoto, M.; Brajša, R.; Skokić, I.; Bárta, M.; Kim, S.; de Gregorio-Monsalvo, I.; Corder, S. A.; Hudson, H. S.; Wedemeyer, S.; Gary, D. E.; De Pontieu, B.; Loukitcheva, M.; Fleishman, G. D.; Chen, B.; Kobelski, A.; Yan, Y.

    2017-07-01

    Observations of the Sun at millimeter and submillimeter wavelengths offer a unique probe into the structure, dynamics, and heating of the chromosphere; the structure of sunspots; the formation and eruption of prominences and filaments; and energetic phenomena such as jets and flares. High-resolution observations of the Sun at millimeter and submillimeter wavelengths are challenging due to the intense, extended, low-contrast, and dynamic nature of emission from the quiet Sun, and the extremely intense and variable nature of emissions associated with energetic phenomena. The Atacama Large Millimeter/submillimeter Array (ALMA) was designed with solar observations in mind. The requirements for solar observations are significantly different from observations of sidereal sources and special measures are necessary to successfully carry out this type of observations. We describe the commissioning efforts that enable the use of two frequency bands, the 3-mm band (Band 3) and the 1.25-mm band (Band 6), for continuum interferometric-imaging observations of the Sun with ALMA. Examples of high-resolution synthesized images obtained using the newly commissioned modes during the solar-commissioning campaign held in December 2015 are presented. Although only 30 of the eventual 66 ALMA antennas were used for the campaign, the solar images synthesized from the ALMA commissioning data reveal new features of the solar atmosphere that demonstrate the potential power of ALMA solar observations. The ongoing expansion of ALMA and solar-commissioning efforts will continue to enable new and unique solar observing capabilities.

  1. Optimization of multi-pulse sequences for nonlinear contrast agent imaging using a cMUT array.

    Science.gov (United States)

    Novell, Anthony; Arena, Christopher B; Kasoji, Sandeep; Dayton, Paul A

    2015-04-21

    Capacitive micromachined ultrasonic transducer (cMUT) technology provides advantages such as wide frequency bandwidth, which can be exploited for contrast agent imaging. Nevertheless, the efficiency of traditional multi-pulse imaging schemes, such as pulse inversion (PI), remains limited because of the intrinsic nonlinear character of cMUTs. Recently, a new contrast imaging sequence, called bias voltage modulation sequence (BVM), has been specifically developed for cMUTs to suppress their unwanted nonlinear behavior. In this study, we propose to optimize contrast agent detection by combining the BVM sequence with PI and/or chirp reversal (CR). An aqueous dispersion of lipid encapsulated microbubbles was exposed to several combinations of multi-pulse imaging sequences. Approaches were evaluated in vitro using 9 inter-connected elements of a cMUT linear array (excitation frequency of 4 MHz; peak negative pressure of 100 kPa). For sequences using chirp excitations, a specific compression filter was designed to compress and extract several nonlinear components from the received microbubble responses. A satisfactory cancellation of the nonlinear signal from the source is achieved when BVM is combined with PI and CR. In comparison with PI and CR imaging modes alone, using sequences incorporating BVM increases the contrast-to-tissue ratio by 10.0 dB and 4.6 dB, respectively. Furthermore, the combination of BVM with CR and PI results in a significant increase of the contrast-to-noise ratio (+29 dB). This enhancement is attributed to the use of chirps as excitation signals and the improved preservation of several nonlinear components contained within the contrast agent response.

  2. Real-Time Imaging with Frequency Scanning Array Antenna for Industrial Inspection Applications at W band

    Science.gov (United States)

    Larumbe, Belen; Laviada, Jaime; Ibáñez-Loinaz, Asier; Teniente, Jorge

    2017-09-01

    A real-time imaging system based on a frequency scanning antenna for conveyor belt setups is presented in this paper. The frequency scanning antenna together with an inexpensive parabolic reflector operates at the W band enabling the detection of details with dimensions in the order of 2 mm. In addition, a low level of sidelobes is achieved by optimizing unequal dividers to window the power distribution for sidelobe reduction. Furthermore, the quality of the images is enhanced by the radiation pattern properties. The performance of the system is validated by showing simulation as well as experimental results obtained in real time, proving the feasibility of these kinds of frequency scanning antennas for cost-effective imaging applications.

  3. Real-Time Imaging with Frequency Scanning Array Antenna for Industrial Inspection Applications at W band

    Science.gov (United States)

    Larumbe, Belen; Laviada, Jaime; Ibáñez-Loinaz, Asier; Teniente, Jorge

    2018-01-01

    A real-time imaging system based on a frequency scanning antenna for conveyor belt setups is presented in this paper. The frequency scanning antenna together with an inexpensive parabolic reflector operates at the W band enabling the detection of details with dimensions in the order of 2 mm. In addition, a low level of sidelobes is achieved by optimizing unequal dividers to window the power distribution for sidelobe reduction. Furthermore, the quality of the images is enhanced by the radiation pattern properties. The performance of the system is validated by showing simulation as well as experimental results obtained in real time, proving the feasibility of these kinds of frequency scanning antennas for cost-effective imaging applications.

  4. A virtually imaged defocused array (VIDA) for high-speed 3D microscopy.

    Science.gov (United States)

    Schonbrun, Ethan; Di Caprio, Giuseppe

    2016-10-01

    We report a method to capture a multifocus image stack based on recording multiple reflections generated by imaging through a custom etalon. The focus stack is collected in a single camera exposure and consequently the information needed for 3D reconstruction is recorded in the camera integration time, which is only 100 µs. We have used the VIDA microscope to temporally resolve the multi-lobed 3D morphology of neutrophil nuclei as they rotate and deform through a microfluidic constriction. In addition, we have constructed a 3D imaging flow cytometer and quantified the nuclear morphology of nearly a thousand white blood cells flowing at a velocity of 3 mm per second. The VIDA microscope is compact and simple to construct, intrinsically achromatic, and the field-of-view and stack number can be easily reconfigured without redesigning diffraction gratings and prisms. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Wall Clutter Mitigation in Through-the-Wall Imaging Radar with Sparse Array Antenna Based on Independent Component Analysis

    Directory of Open Access Journals (Sweden)

    Zhang Chi

    2014-10-01

    Full Text Available For Through-the-Wall Imaging Radar (TWIR, wall clutter is critical for detecting target signals behind a wall. For a system with a sparse antenna array, the lack of observation channels makes it more difficult to separate the target signals and wall clutter. On the basis of fluctuation of the range profile in real transmit/receive channels, this paper proposes to use Independent Component Analysis (ICA on multiple down-range observations of each transmit/receive channel to remove the wall clutter. The simulation and experimental results show that the proposed method effectively separate target and clutter components, even though the signal-to-clutter ratio is only -30 dB.

  6. 640 x 512 Pixels Long-Wavelength Infrared (LWIR) Quantum-Dot Infrared Photodetector (QDIP) Imaging Focal Plane Array

    Science.gov (United States)

    Gunapala, Sarath D.; Bandara, Sumith V.; Hill, Cory J.; Ting, David Z.; Liu, John K.; Rafol, Sir B.; Blazejewski, Edward R.; Mumolo, Jason M.; Keo, Sam A.; Krishna, Sanjay; hide

    2007-01-01

    Epitaxially grown self-assembled. InAs-InGaAs-GaAs quantum dots (QDs) are exploited for the development of large-format long-wavelength infrared focal plane arrays (FPAs). The dot-in-a-well (DWELL) structures were experimentally shown to absorb both 45 degrees and normal incident light, therefore, a reflection grating structure was used to enhance the quantum efficiency. The devices exhibit peak responsivity out to 8.1 micrometers, with peak detectivity reaching approximately 1 X 10(exp 10) Jones at 77 K. The devices were fabricated into the first long-wavelength 640 x 512 pixel QD infrared photodetector imaging FPA, which has produced excellent infrared imagery with noise equivalent temperature difference of 40 mK at 60-K operating temperature.

  7. Status of the Whipple Observatory Cerenkov air shower imaging telescope array

    Science.gov (United States)

    Akerlof, C. W.; Cawley, M. F.; Fegan, D. J.; Fennell, S.; Freeman, S.; Frishman, D.; Harris, K.; Hillas, A. M.; Jennings, D.; Lamb, R. C.

    1992-01-01

    Recently the power of the Cerenkov imaging technique in Very High Energy gamma-ray astronomy was demonstrated by the detection of the Crab nebula at high statistical significance. In order to further develop this technique to allow the detection of weaker or more distant sources a second 10 m class reflector was constructed about 120 m from the original instrument. The addition of the second reflector will allow both a reduction in the energy threshold and an improvement in the rejection of the hadronic background. The design and construction of the second reflector, Gamma Ray Astrophysics New Imaging TElescope (GRANITE) is described.

  8. Focal plane array detectors with micro-bolometer structure and its application in IR and THz imaging

    Science.gov (United States)

    Wang, Jun; Mou, Wenchao; Gou, Jun; Jiang, Yadong

    2016-10-01

    Focal Plane Array (FPA) detector has characteristics of low cost, operating at room temperature, compatibility with the silicon CMOS technology, and high detecting performance, therefore it becomes a hot spot in infrared (IR) or terahertz (THz) detect field recently. However, the tradition structure of micro-bolometer has the conflict of the pixel size and thermal performance. In order to improve the detecting performance of small pixel size bolometer, high fill factor and low thermal conductance design should be considered. In IR detecting, double layers structure is an efficient method to improve the absorption of micro-bolometer and reduce thermal conductance. The three-dimension model of small size micro-bolometer was built in this article. The thermal and mechanical characters of those models were simulated and optimized, and finally the double layer structure micro-bolometer was fabricated with multifarious semiconductor recipes on the readout integrated chip wafer. For THz detecting, to improve the detecting performance, different dimension THz detectors based on micro-bridge structure were designed and fabricated to get optimizing micro-bolometer parameters from the test results of membrane deformation. A nanostructured titanium thin film absorber is integrated in the micro-bridge structure of the VOx micro-bolometer to enhance the absorption of THz radiation. Continuous-wave THz detection and imaging are demonstrated with a 2.52 THz far infrared CO2 laser and fabricated 320×240 vanadium oxide micro-bolometer focal plane array with optimized cell structure. With this detecting system, THz imaging of metal concealed in wiping cloth and envelope is demonstrated.

  9. Experimental Demonstration of Adaptive Infrared Multispectral Imaging Using Plasmonic Filter Array (Postprint)

    Science.gov (United States)

    2016-10-10

    three different types of color-sensing elements. Analogous to the functionality of the lens and the film in a camera, an image of the visual world is...photoreceptor cells are light sensitive elements, mainly of two types: rods and cones. Particularly, cones support daytime vision and the perception of color

  10. Subarcminute Resolution Imaging of Radio Sources at 74 MHz with the Very Large Array

    National Research Council Canada - National Science Library

    Kassim, N. E; Perley, R. A; Erickson, W. C; Dwarakanath, K. S

    1993-01-01

    .... Although the system is of low efficiency, it works well for imaging strong sources (S ̃ > 20O Jy) on long baselines (> 5 km) since self-calibration has sufficient signal to noise to remove phase errors on the short time scales...

  11. LOFAR tied-array imaging of Type III solar radio bursts

    NARCIS (Netherlands)

    Morosan, D.E.; et al., [Unknown; Hessels, J.W.T.; Markoff, S.

    2014-01-01

    Context. The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), the Sun has not been imaged extensively because of the instrumental limitations of previous radio

  12. LOFAR tied-array imaging of Type III solar radio bursts

    NARCIS (Netherlands)

    Morosan, D.E.; Gallagher, P.T.; Zucca, P.; Fallows, R.; Carley, E.P.; Mann, G.; Bisi, M.M.; Kerdraon, A.; Avruch, I.M.; Bentum, Marinus Jan; Bernardi, G.; Best, P.; Bonafede, A.; Bregman, J.; Breitling, F.

    2014-01-01

    Context: The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (<100 MHz), the Sun has not been imaged extensively because of the instrumental limitations of previous radio

  13. Short-Range Ultra-Wideband Imaging with Multiple-Input Multiple-Output Arrays

    NARCIS (Netherlands)

    Zhuge, X.

    2010-01-01

    Compact, cost-efficient and high-resolution imaging sensors are especially desirable in the field of short-range observation and surveillance. Such sensors are of great value in fields of security, rescue and medical applications. Systems can be formed for various practical purposes, such as

  14. Auralizations with loudspeaker arrays from a phased combination of the image source method and acoustical radiosity

    DEFF Research Database (Denmark)

    Marbjerg, Gerd Høy; Brunskog, Jonas; Jeong, Cheol-Ho

    2017-01-01

    In order to create a simulation tool that is well-suited for small rooms with low diffusion and highly absorbing ceilings, a new room acoustic simulation tool has been developed that combines a phased version of the image source with acoustical radiosity and that considers the angle dependence of...

  15. A line array based near field imaging technique for characterising acoustical properties of elongated targets

    NARCIS (Netherlands)

    Driessen, F.P.G.

    1995-01-01

    With near field imaging techniques the acoustical pressure waves at distances other than the recorded can be calculated. Normally, acquisition on a two dimensional plane is necessary and extrapolation is performed by a Rayleigh integral. A near field single line instead of two dimensional plane

  16. 3D near-infrared imaging based on a single-photon avalanche diode array sensor

    NARCIS (Netherlands)

    Mata Pavia, J.; Charbon, E.; Wolf, M.

    2011-01-01

    An imager for optical tomography was designed based on a detector with 128x128 single-photon pixels that included a bank of 32 time-to-digital converters. Due to the high spatial resolution and the possibility of performing time resolved measurements, a new contact-less setup has been conceived in

  17. Fabrication and experimental observation of monolithic multi-air-core fiber array for image transmission.

    Science.gov (United States)

    Wang, Jian; Yang, Xinghua; Wang, Lili

    2008-05-26

    Two kinds of multi-air-core optical fibers were designed and fabricated by extruding optical grade PMMA pellets and drawing to fiber. The imaging function of the fibers was investigated with home-made specialized microscopy. This new type of fiber provides strong potential for applications in endoscopy, chemical sensing, biosensors, fiber-optical faceplates.

  18. Sub-micron resolution surface plasmon resonance imaging enabled by nanohole arrays with surrounding Bragg mirrors for enhanced sensitivity and isolation.

    Science.gov (United States)

    Lindquist, Nathan C; Lesuffleur, Antoine; Im, Hyungsoon; Oh, Sang-Hyun

    2009-02-07

    We present nanohole arrays in thin gold films as sub-micron resolution surface plasmon resonance (SPR) imaging pixels in a microarray format. With SPR imaging, the resolution is not limited by diffraction, but by the propagation of surface plasmon waves to adjacent sensing areas, or nanohole arrays, causing unwanted interference. For ultimate scalability, several issues need to be addressed, including: (1) as several nanohole arrays are brought close to each other, surface plasmon interference introduces large sources of error; and (2) as the size of the nanohole array is reduced, i.e. fewer holes, detection sensitivity suffers. To address these scalability issues, we surround each biosensing pixel (a 3-by-3 nanohole array) with plasmonic Bragg mirrors, blocking interference between adjacent SPR sensing pixels for high-density packing, while maintaining the sensitivity of a 50 x larger footprint pixel (a 16-by-16 nanohole array). We measure real-time, label-free streptavidin-biotin binding kinetics with a microarray of 600 sub-micron biosensing pixels at a packing density of more than 10(7) per cm(2).

  19. Submillimeter Array 12CO (2-1) Imaging of the NGC 6946 Giant Molecular Clouds

    Science.gov (United States)

    Wu, Ya-Lin; Sakamoto, Kazushi; Pan, Hsi-An

    2017-04-01

    We present a 12CO (2-1) mosaic map of the spiral galaxy NGC 6946 by combining data from the Submillimeter Array and the IRAM 30 m telescope. We identify 390 giant molecular clouds (GMCs) from the nucleus to 4.5 kpc in the disk. GMCs in the inner 1 kpc are generally more luminous and turbulent, some of which have luminosities >106 K km s-1 pc2 and velocity dispersions >10 km s-1. Large-scale bar-driven dynamics likely regulate GMC properties in the nuclear region. Similar to the Milky Way and other disk galaxies, GMC mass function of NGC 6946 has a shallower slope (index > -2) in the inner region, and a steeper slope (index outer region. This difference in mass spectra may be indicative of different cloud formation pathways: gravitational instabilities might play a major role in the nuclear region, while cloud coalescence might be dominant in the outer disk. Finally, the NGC 6946 clouds are similar to those in M33 in terms of statistical properties, but they are generally less luminous and turbulent than the M51 clouds.

  20. Imaging and Interpreting Lithospheric Structure in the Southern Appalachians using the SESAME Broadband Array

    Science.gov (United States)

    Verellen, D.; Alberts, E.; Parker, H., Jr.; Hawman, R. B.; Fischer, K. M.; Wagner, L. S.

    2016-12-01

    The Southeastern Suture of the Appalachian Margin Experiment (SESAME) was designed to investigate the role of crustal and subcrustal deformation associated with Alleghanian collision and Mesozoic extension of the lithosphere across the southeastern United States. It involved the deployment of three profiles with a total length of 1300 kilometers. In this study, we use zero-offset reflections generated by the global seismic phase PKIKP as a virtual source to image structure within the lithosphere. Together with Consortium for Continental Reflection Profiling (COCORP) surveys, these data allow us to study the nature of the Moho and other discontinuities over a wide range of scales. A major objective of this work is to track variations in the detailed structure of the crust-mantle transition from Grenville basement beneath the Valley & Ridge to accreted terranes beneath the Coastal Plain and across the boundary between Laurentian and Gondwanan lithosphere. We also investigate the scale of layering in the uppermost mantle and its possible relation to contrasts in anisotropy in relation to shearing. Preliminary findings for a single earthquake (mb=6.1) recorded along a profile trending northwest across the Carolina Terrane, Inner Piedmont, and Blue Ridge show dipping reflectors at a depth of approximately 15-20 km in the crust, and layered, relatively flat-lying reflectors at a depth of roughly 70 km in the upper mantle. Ongoing work includes stacking of waveforms for multiple events in order to enhance signal-to-noise levels and construction of images for two additional north-south trending profiles across the Coastal Plain, where deep structure is more difficult to image due to reverberations within low-velocity sediments. The resulting broadband images of P-wave reflectivity will be used in combination with models of S-wave reflectivity derived by other methods to provide insight into the complex deformational history of the southern Appalachian system.

  1. Laser-induced breakdown spectroscopy combined with spatial heterodyne spectroscopy.

    Science.gov (United States)

    Gornushkin, Igor B; Smith, Ben W; Panne, Ulrich; Omenetto, Nicoló

    2014-01-01

    A spatial heterodyne spectrometer (SHS) is tested for the first time in combination with laser-induced breakdown spectroscopy (LIBS). The spectrometer is a modified version of the Michelson interferometer in which mirrors are replaced by diffraction gratings. The SHS contains no moving parts and the gratings are fixed at equal distances from the beam splitter. The main advantage is high throughput, about 200 times higher than that of dispersive spectrometers used in LIBS. This makes LIBS-SHS a promising technique for low-light standoff applications. The output signal of the SHS is an interferogram that is Fourier-transformed to retrieve the original plasma spectrum. In this proof-of-principle study, we investigate the potential of LIBS-SHS for material classification and quantitative analysis. Brass standards with broadly varying concentrations of Cu and Zn were tested. Classification via principal component analysis (PCA) shows distinct groupings of materials according to their origin. The quantification via partial least squares regression (PLS) shows good precision (relative standard deviation < 10%) and accuracy (within ± 5% of nominal concentrations). It is possible that LIBS-SHS can be developed into a portable, inexpensive, rugged instrument for field applications.

  2. A simple and versatile phase detector for heterodyne interferometers.

    Science.gov (United States)

    Mlynek, A; Faugel, H; Eixenberger, H; Pautasso, G; Sellmair, G

    2017-02-01

    The measurement of the relative phase of two sinusoidal electrical signals is a frequently encountered task in heterodyne interferometry, but also occurs in many other applications. Especially in interferometry, multi-radian detectors are often required, which track the temporal evolution of the phase difference and are able to register phase changes that exceed 2π. While a large variety of solutions to this problem is already known, we present an alternative approach, which pre-processes the signals with simple analog circuitry and digitizes two resulting voltages with an analog-to-digital converter (ADC), whose sampling frequency can be far below the frequency of the sinusoidal signals. Phase reconstruction is finally carried out by software. The main advantage of this approach is its simplicity, using only few low-cost hardware components and a standard 2-channel ADC with low performance requirements. We present an application on the two-color interferometer of the ASDEX Upgrade tokamak, where the relative phase of 40 MHz sinusoids is measured.

  3. Observing Quantum State Diffusion by Heterodyne Detection of Fluorescence

    Directory of Open Access Journals (Sweden)

    P. Campagne-Ibarcq

    2016-01-01

    Full Text Available A qubit can relax by fluorescence, which prompts the release of a photon into its electromagnetic environment. By counting the emitted photons, discrete quantum jumps of the qubit state can be observed. The succession of states occupied by the qubit in a single experiment, its quantum trajectory, depends in fact on the kind of detector. How are the quantum trajectories modified if one measures continuously the amplitude of the fluorescence field instead? Using a superconducting parametric amplifier, we perform heterodyne detection of the fluorescence of a superconducting qubit. For each realization of the measurement record, we can reconstruct a different quantum trajectory for the qubit. The observed evolution obeys quantum state diffusion, which is characteristic of quantum measurements subject to zero-point fluctuations. Independent projective measurements of the qubit at various times provide a quantitative verification of the reconstructed trajectories. By exploring the statistics of quantum trajectories, we demonstrate that the qubit states span a deterministic surface in the Bloch sphere at each time in the evolution. Additionally, we show that when monitoring fluorescence field quadratures, coherent superpositions are generated during the decay from excited to ground state. Counterintuitively, measuring light emitted during relaxation can give rise to trajectories with increased excitation probability.

  4. Strain Library Imaging Protocol for high-throughput, automated single-cell microscopy of large bacterial collections arrayed on multiwell plates.

    Science.gov (United States)

    Shi, Handuo; Colavin, Alexandre; Lee, Timothy K; Huang, Kerwyn Casey

    2017-02-01

    Single-cell microscopy is a powerful tool for studying gene functions using strain libraries, but it suffers from throughput limitations. Here we describe the Strain Library Imaging Protocol (SLIP), which is a high-throughput, automated microscopy workflow for large strain collections that requires minimal user involvement. SLIP involves transferring arrayed bacterial cultures from multiwell plates onto large agar pads using inexpensive replicator pins and automatically imaging the resulting single cells. The acquired images are subsequently reviewed and analyzed by custom MATLAB scripts that segment single-cell contours and extract quantitative metrics. SLIP yields rich data sets on cell morphology and gene expression that illustrate the function of certain genes and the connections among strains in a library. For a library arrayed on 96-well plates, image acquisition can be completed within 4 min per plate.

  5. Photon-counting hexagonal pixel array CdTe detector: Spatial resolution characteristics for image-guided interventional applications

    Energy Technology Data Exchange (ETDEWEB)

    Vedantham, Srinivasan; Shrestha, Suman; Karellas, Andrew, E-mail: andrew.karellas@umassmed.edu; Shi, Linxi; Gounis, Matthew J. [Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655 (United States); Bellazzini, Ronaldo; Spandre, Gloria; Brez, Alessandro; Minuti, Massimo [Istituto Nazionale di Fisica Nucleare (INFN), Pisa 56127, Italy and Pixirad Imaging Counters s.r.l., L. Pontecorvo 3, Pisa 56127 (Italy)

    2016-05-15

    Purpose: High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. Methods: A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixel pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. Results: At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54

  6. Photon-counting hexagonal pixel array CdTe detector: Spatial resolution characteristics for image-guided interventional applications

    Science.gov (United States)

    Shrestha, Suman; Karellas, Andrew; Shi, Linxi; Gounis, Matthew J.; Bellazzini, Ronaldo; Spandre, Gloria; Brez, Alessandro; Minuti, Massimo

    2016-01-01

    Purpose: High-resolution, photon-counting, energy-resolved detector with fast-framing capability can facilitate simultaneous acquisition of precontrast and postcontrast images for subtraction angiography without pixel registration artifacts and can facilitate high-resolution real-time imaging during image-guided interventions. Hence, this study was conducted to determine the spatial resolution characteristics of a hexagonal pixel array photon-counting cadmium telluride (CdTe) detector. Methods: A 650 μm thick CdTe Schottky photon-counting detector capable of concurrently acquiring up to two energy-windowed images was operated in a single energy-window mode to include photons of 10 keV or higher. The detector had hexagonal pixels with apothem of 30 μm resulting in pixel pitch of 60 and 51.96 μm along the two orthogonal directions. The detector was characterized at IEC-RQA5 spectral conditions. Linear response of the detector was determined over the air kerma rate relevant to image-guided interventional procedures ranging from 1.3 nGy/frame to 91.4 μGy/frame. Presampled modulation transfer was determined using a tungsten edge test device. The edge-spread function and the finely sampled line spread function accounted for hexagonal sampling, from which the presampled modulation transfer function (MTF) was determined. Since detectors with hexagonal pixels require resampling to square pixels for distortion-free display, the optimal square pixel size was determined by minimizing the root-mean-squared-error of the aperture functions for the square and hexagonal pixels up to the Nyquist limit. Results: At Nyquist frequencies of 8.33 and 9.62 cycles/mm along the apothem and orthogonal to the apothem directions, the modulation factors were 0.397 and 0.228, respectively. For the corresponding axis, the limiting resolution defined as 10% MTF occurred at 13.3 and 12 cycles/mm, respectively. Evaluation of the aperture functions yielded an optimal square pixel size of 54

  7. Controlling system for smart hyper-spectral imaging array based on liquid-crystal Fabry-Perot device

    Science.gov (United States)

    Jiang, Xue; Chen, Xin; Rong, Xin; Liu, Kan; Zhang, Xinyu; Ji, An; Xie, Changsheng

    2011-11-01

    A research for developing a kind of smart spectral imaging detection technique based on the electrically tunable liquidcrystal (LC) FP structure is launched. It has some advantages of low cost, highly compact integration, perfuming wavelength selection without moving any micro-mirror of FP device, and the higher reliability and stability. The controlling system for hyper-spectral imaging array based on LC-FP device includes mainly a MSP430F5438 as its core. Considering the characteristics of LC-FP device, the controlling system can provide a driving signal of 1-10 kHz and 0- 30Vrms for the device in a static driving mode. This paper introduces the hardware designing of the control system in detail. It presents an overall hardware solutions including: (1) the MSP430 controlling circuit, and (2) the operational amplifier circuit, and (3) the power supply circuit, and (4) the AD conversion circuit. The techniques for the realization of special high speed digital circuits, which is necessary for the PCB employed, is also discussed.

  8. Real-time photoacoustic and ultrasound imaging: a simple solution for clinical ultrasound systems with linear arrays.

    Science.gov (United States)

    Montilla, Leonardo G; Olafsson, Ragnar; Bauer, Daniel R; Witte, Russell S

    2013-01-07

    Recent clinical studies have demonstrated that photoacoustic imaging (PAI) provides important diagnostic information during a routine breast exam for cancer. PAI enhances contrast between blood vessels and background tissue, which can help characterize suspicious lesions. However, most PAI systems are either not compatible with commercial ultrasound systems or inefficiently deliver light to the region of interest, effectively reducing the sensitivity of the technique. To address and potentially overcome these limitations, we developed an accessory for a standard linear ultrasound array that optimizes light delivery for PAI. The photoacoustic enabling device (PED) exploits an optically transparent acoustic reflector to help direct laser illumination to the region of interest. This study compares the PED with standard fiber bundle illumination in scattering and non-scattering media. In scattering media with the same incident fluence, the PED enhanced the photoacoustic signal by 18 dB at a depth of 5 mm and 6 dB at a depth of 20 mm. To demonstrate in vivo feasibility, we also used the device to image a mouse with a pancreatic tumor. The PED identified blood vessels at the periphery of the tumor, suggesting that PAI provides complementary contrast to standard pulse echo ultrasound. The PED is a simple and inexpensive solution that facilitates the translation of PAI technology to the clinic for routine screening of breast cancer.

  9. Observations of a Cold Front at High Spatiotemporal Resolution Using an X-Band Phased Array Imaging Radar

    Directory of Open Access Journals (Sweden)

    Andrew Mahre

    2017-02-01

    Full Text Available While the vertical structure of cold fronts has been studied using various methods, previous research has shown that traditional methods of observing meteorological phenomena (such as pencil-beam radars in PPI/volumetric mode are not well-suited for resolving small-scale cold front phenomena, due to relatively low spatiotemporal resolution. Additionally, non-simultaneous elevation sampling within a vertical cross-section can lead to errors in analysis, as differential vertical advection cannot be distinguished from temporal evolution. In this study, a cold front from 19 September 2015 is analyzed using the Atmospheric Imaging Radar (AIR. The AIR transmits a 20-degree fan beam in elevation, and digital beamforming is used on receive to generate simultaneous receive beams. This mobile, X-band, phased-array radar offers temporal sampling on the order of 1 s (while in RHI mode, range sampling of 30 m (37.5 m native resolution, and continuous, arbitrarily oversampled data in the vertical dimension. Here, 0.5-degree sampling is used in elevation (1-degree native resolution. This study is the first in which a cold front has been studied via imaging radar. The ability of the AIR to obtain simultaneous RHIs at high temporal sampling rates without mechanical steering allows for analysis of features such as Kelvin-Helmholtz instabilities and feeder flow.

  10. Silicon Micromachined Heterodyne Array Receiver at 1.9 THz Project

    Data.gov (United States)

    National Aeronautics and Space Administration — "We are proposing a new concept of integrated component development technology at submillimeter wavelengths that will dramatically simplify the fabrication,...

  11. Optimization of a phased-array transducer for multiple harmonic imaging in medical applications: frequency and topology.

    Science.gov (United States)

    Matte, Guillaume M; Van Neer, Paul L M J; Danilouchkine, Mike G; Huijssen, Jacob; Verweij, Martin D; de Jong, Nico

    2011-03-01

    Second-harmonic imaging is currently one of the standards in commercial echographic systems for diagnosis, because of its high spatial resolution and low sensitivity to clutter and near-field artifacts. The use of nonlinear phenomena mirrors is a great set of solutions to improve echographic image resolution. To further enhance the resolution and image quality, the combination of the 3rd to 5th harmonics--dubbed the superharmonics--could be used. However, this requires a bandwidth exceeding that of conventional transducers. A promising solution features a phased-array design with interleaved low- and high-frequency elements for transmission and reception, respectively. Because the amplitude of the backscattered higher harmonics at the transducer surface is relatively low, it is highly desirable to increase the sensitivity in reception. Therefore, we investigated the optimization of the number of elements in the receiving aperture as well as their arrangement (topology). A variety of configurations was considered, including one transmit element for each receive element (1/2) up to one transmit for 7 receive elements (1/8). The topologies are assessed based on the ratio of the harmonic peak pressures in the main and grating lobes. Further, the higher harmonic level is maximized by optimization of the center frequency of the transmitted pulse. The achievable SNR for a specific application is a compromise between the frequency-dependent attenuation and nonlinearity at a required penetration depth. To calculate the SNR of the complete imaging chain, we use an approach analogous to the sonar equation used in underwater acoustics. The generated harmonic pressure fields caused by nonlinear wave propagation were modeled with the iterative nonlinear contrast source (INCS) method, the KZK, or the Burger's equation. The optimal topology for superharmonic imaging was an interleaved design with 1 transmit element per 6 receive elements. It improves the SNR by ~5 dB compared with

  12. Rectal cancer confined to the bowel wall: the role of 3 Tesla phased-array MR imaging in T categorization.

    Science.gov (United States)

    Çolakoğlu Er, Hale; Peker, Elif; Erden, Ayşe; Erden, İlhan; Geçim, Ethem; Savaş, Berna

    2017-11-21

    To determine the diagnostic value of 3 Tesla MR imaging in detection of mucosal (Tis), submucosal (T1) and muscularis propria (T2) invasion in patients with early rectal cancer. A total of 50 consecutive patients who underwent 3 Tesla MR imaging and curative-intent intervention for MRI-staged Tis/T1/T2 rectal cancer from March 2012 to December 2016 were included. The radiological T category of each rectal tumour was compared retrospectively with histopathological results assessed according to the tumor, node, metastasis (TNM) classification. The sensitivities, specificities, and overall accuracy rates of 3 Tesla MR imaging for Tis, T1, and T2 cases were calculated using MedCalc statistical software v. 16. The sensitivity, specificity, PPV, NPV of 3 Tesla MR imaging in T categorization for T2 were: 93.7% [95% CI (0.79-0.99)], 77.7% [95% CI (0.52-0.93)], 88.2% [95% CI (0.75-0.94)] and 87.5% [95% CI (0.64-0.96)]; for T1 were 92% [95% CI (0.63-0.99)], 91.8% [95% CI (0.78-0.98)], 80% [95% CI (0.57-0.92)] and 97.1% [95% CI (0.83-0.99)]; for Tis were: 20% [95% CI (0.51-0.71)], 100% [95% CI (0.92-1)], 100%, 91.8% [95% CI (0.87-0.94)], respectively. MR categorization accuracy rates for T2, T1 and Tis were calculated as 88, 92 and 92%, respectively. 3 Tesla MR imaging seems to be useful for accurate categorization of T-stage in early rectal cancer, especially for T1 cancers. The method is not a reliable tool to detect Tis cases. The potential for overstaging and understaging of the technique should be realized and taken into consideration when tailoring the treatment protocol for each patient. Advances in knowledge: High-resolution MR with phased-array coil is being increasingly used in the pre-operative assessment of rectal cancer. 3 Tesla high-resolution MR imaging allows improved definition of bowel wall and tumour infiltration.

  13. Digital electronics for 256 anode Hamamatsu H9500 PSPMT arrays in full-volume Compton imagers

    Science.gov (United States)

    Harris, J. T.; Grudberg, P. M.; Warburton, W. K.

    2014-07-01

    Ziock et al.'s [1] recent Monte Carlo study of a proposed ``full-volume'' Compton Imaging Camera concluded that simultaneously locating a Compton scatter event's multiple interaction points within a single large scintillator crystal might be possible at 1 mm spatial resolution using a coded aperture mask sandwiched between two light guides and coupled to a position sensitive photomultiplier (PSPMT) to record the output light pattern. The method promises high efficiency at a relatively low cost. They are currently developing a lower resolution prototype using a large cubic scintillator (25.4 cm/side) whose masked face will be tiled with 25 Hamamatsu H9500 PSPMTs (6,400 outputs). XIA has contracted to develop and produce the readout electronics, which present several significant design challenges, including capturing all 6,400 anode outputs individually, with single photon sensitivity, in a compact format that will fit behind the tiled PSPMTs. 10,000 event/sec operation is desired, as is a cost of less than about 50/channel. In our approach, each PSPMT front end integrates the 256 anode signals and 8-1 multiplexes them to 32 differential outputs that are digitized in a PXI card using 4 octal 50 MHz ADCs. The multiplexers run at 8 MHz, sampling each anode at 1 MHz, which becomes the image frame rate. The ADC signals are demultiplexed and digitally filtered to extract the number of photons in each pixel in the full 2-D image. The design has been completed and built and is undergoing evaluation tests at the single PSPMT level.

  14. A 2 x 2 imaging MIMO system based on LED Visible Light Communications employing space balanced coding and integrated PIN array reception

    DEFF Research Database (Denmark)

    Li, Jiehui; Xu, Yinfan; Shi, Jianyang

    2016-01-01

    In this paper, we proposed a 2 x 2 imaging Multi-Input Multi-Output (MIMO)-Visible Light Communication (VLC) system by employing Space Balanced Coding (SBC) based on two RGB LEDs and integrated PIN array reception. We experimentally demonstrated 1.4-Gbit/s VLC transmission at a distance of 2.5 m...

  15. Performance evaluation of a digital intraoral imaging device based on the CMOS photosensor array coupled with an integrated X-ray conversion fiber-optic faceplate

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hyosung [Department of Radiological Science, Yonsei University, 234 Maeji Heungup, Wonju 220 710 (Korea, Republic of)], E-mail: hscho1@yonsei.ac.kr; Choi, Sungil [Department of Radiological Science, Yonsei University, 234 Maeji Heungup, Wonju 220 710 (Korea, Republic of); Kim, Jongguk [Department of Physics, Myongji University, 38-2 Namdong Cheuingu, Yongin 449 728 (Korea, Republic of); Koo, Yangseo; Kim, Taewoo; Ro, Changjoon [Radiation Technology Laboratory, Vatech Co., Ltd., 75-11 Seogu Dongtan, Hwaseong 445 811 (Korea, Republic of); Lee, Bongsoo [School of Biomedical Engineering, Konkuk University, 322 Danweul, Chungju 380 701 (Korea, Republic of); Kim, Sin [Department of Nuclear and Energy Engineering, Cheju National University, 66 Chejudaehakro, Cheju 690 756 (Korea, Republic of); Kim, Hokyung [School of Mechanical Engineering, Pusan National University, 30 Jangjeun Geumjung, Pusan 609 735 (Korea, Republic of)

    2007-08-21

    As a continuation of our digital X-ray imaging sensor R and D, we have developed a cost-effective, intraoral imaging device based on the complementary-metal-oxide semiconductor (CMOS) photosensor array coupled with an integrated X-ray conversion fiber-optic faceplate. It consists of a commercially available CMOS photosensor of a 35x35 {mu}m{sup 2} pixel size and a 688x910 pixel array dimension, and a high-efficiency columnar CsI(Tl) scintillator of a 90 {mu}m thickness directly deposited on a fiber-optic faceplate of a 6 {mu}m core size and an 1.46 mm thickness with 85/15 core-cladding ratio (NA{approx}1.0 in air). The fiber-optic faceplate is a highly X-ray attenuating material that minimizes X-ray absorption on the end CMOS photosensor array, thus, minimizing X-ray induced noise at the photosensor array. It uses a high light-output columnar CsI(Tl) scintillator with a peak spectral emission at 545 nm, giving better spatial resolution, but attenuates some of this light due to interfacial and optical attenuation factors. In this paper, we presented the performance analysis of the intraoral imaging device with experimental measurements and acquired X-ray images in terms of modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE)

  16. Ground based mid-IR heterodyne spectrometer concept for planetary atmospheres observations

    Science.gov (United States)

    Garamov, V.; Benderov, O.; Semenov, V.; Spiridonov, M.; Rodin, A.; Stepanov, B.

    2017-09-01

    We present a heterodyne spectrometer concept based on distributed feedback (DFB) quantum cascade lasers (QCL) operated in midle infrared region (MIR). The instrument is assumed to be mount on the Russian infrared observatories. The core features of the concept are compact design, utilizing a novel mid-IR fiber optical components and dynamic local oscillator frequency locking using reference molecule absorption line. The instrument characteristics are similar to modern heterodyne devices THIS (Cologne University, Germany) and MILAHI (Tohoku University, Japan) in terms of fundamental parameters, including spectral resolution, spectral coverage in a single observation. At present moment we created laboratory setup including all necessary elements of MIR heterodyne spectrometer. We have studied different components of noises of our system and found optimal value of LO power. The measured signal to noise ratio (SNR) with MCT PD was about 10 times greater than LO's shot noise (theoretical limit of heterodyne technique SNR) and limited by QCL relative intensity noise (RIN). However, applying additional filtering it is possible to reduce this value better than 5 shot noise level, which is typical to TEC cooled MCT PD. Also we demonstrate heterodyne signal measurements using laboratory black body with temperature of 400 oC.

  17. Performance simulation of heterodyne synchronous receiving system in coherent optical communication

    Science.gov (United States)

    Zheng, BaiChao; Tong, ShouFeng

    2015-03-01

    Coherent optical communication technology is currently a hotpot research of communication. Coherent optical communication heterodyne synchronous receiving system is researched. The basic principle of coherent optical communication is introduced in briefly, the heterodyne synchronous receiving system is established in the basis of the principle. A simulation model, charactered as Synchronous receiving system of Coherent Heterodyne, was rightly set up. In addition, with regarding actual device parameters as reference, and under the situation of 2.5Gbps communication rate and 10km as communication distance, Optisystem was operating to accomplish simulation analysis for capacity of this system in different signal-radiation rate and distinguish weather condition. The consequence of simulation demonstrated: as the receiving sensitivity is relatively high when compared communication system of coherent heterodyne to that of IM/DD, the coherent optical communication system has lower requirement to signal rate of radiated laser in the same condition. Consequently, it can be concluded that coherent heterodyne system has high receiving sensitivity, and strong capacity of resisting disturbance, moreover it is appropriately communicated in channel with relatively high disturbance, it possesses great advantages to IM/DD method in atmosphere channel which has strong disturbance.

  18. Auralisations with loudspeaker arrays from a phased combination of the image source method and acoustical radiosity

    DEFF Research Database (Denmark)

    Marbjerg, Gerd Høy

    2017-01-01

    In order to create a simulation tool that is well-suited for small rooms with low diffusion and highly absorbing ceilings, a new room acoustic simulation tool has been developed that combines a phased version of the image source with acoustical radiosity and that considers the angle dependence...... with PARISM are described and compared to implementations of auralisations with another geometrical acoustic simulation tool, i.e. ODEON and the LoRA toolbox that applies Ambisonics to ODEON simulations. In opposition to the LoRA toolbox, higher order Ambisonics are also applied to the late part of the PARISM...

  19. What are “X-shaped” Radio Sources Telling Us? I. Very Large Array Imaging of a Large Sample of Candidate XRGs

    Science.gov (United States)

    Roberts, David H.; Saripalli, Lakshmi; Wang, Kevin X.; Sathyanarayana Rao, Mayuri; Subrahmanyan, Ravi; KleinStern, Carly C.; Morii-Sciolla, Christopher Y.; Simpson, Liana

    2018-01-01

    We present archival and Jansky Very Large Array multi-frequency multi-array radio continuum imaging of a unique sample of 100 radio sources that have been selected to be candidate “X-shaped” radio galaxies (XRGs). The archival data were calibrated in AIPS and imaged using DIFMAP, while the new Very Large Array data were calibrated and imaged in CASA. No attempt was made to re-image the archival data in CASA. Altogether we present images of 95 of the 100 sources. These observations give us the opportunity to study radio sources with synchrotron plasma that is significantly offset from the main radio axis and therefore to open a window into investigations of physical mechanisms responsible for depositing the plasma in off-axis regions. Here, we present the technical details of the observations and all of the total intensity images, while in subsequent papers we use them to examine critically various models for the formation of XRGs. Spectral index and linear polarization information is also presented and analyzed in further papers in this series.

  20. 3D-printed microwell arrays for Ciona microinjection and timelapse imaging.

    Directory of Open Access Journals (Sweden)

    Clint Gregory

    Full Text Available Ascidians such as Ciona are close chordate relatives of the vertebrates with small, simple embryonic body plans and small, simple genomes. The tractable size of the embryo offers considerable advantages for in toto imaging and quantitative analysis of morphogenesis. For functional studies, Ciona eggs are considerably more challenging to microinject than the much larger eggs of other model organisms such as zebrafish and Xenopus. One of the key difficulties is in restraining the eggs so that the microinjection needle can be easily introduced and withdrawn. Here we develop and test a device to cast wells in agarose that are each sized to hold a single egg. This injection mold is fabricated by micro-resolution stereolithography with a grid of egg-sized posts that cast corresponding wells in agarose. This 3D printing technology allows the rapid and inexpensive testing of iteratively refined prototypes. In addition to their utility in microinjection, these grids of embryo-sized wells are also valuable for timelapse imaging of multiple embryos.

  1. Cosmic Infrared Background Fluctuations in Deep Spitzer Infrared Array Camera Images: Data Processing and Analysis

    Science.gov (United States)

    Arendt, Richard; Kashlinsky, A.; Moseley, S.; Mather, J.

    2010-01-01

    This paper provides a detailed description of the data reduction and analysis procedures that have been employed in our previous studies of spatial fluctuation of the cosmic infrared background (CIB) using deep Spitzer Infrared Array Camera observations. The self-calibration we apply removes a strong instrumental signal from the fluctuations that would otherwise corrupt the results. The procedures and results for masking bright sources and modeling faint sources down to levels set by the instrumental noise are presented. Various tests are performed to demonstrate that the resulting power spectra of these fields are not dominated by instrumental or procedural effects. These tests indicate that the large-scale ([greater, similar]30') fluctuations that remain in the deepest fields are not directly related to the galaxies that are bright enough to be individually detected. We provide the parameterization of these power spectra in terms of separate instrument noise, shot noise, and power-law components. We discuss the relationship between fluctuations measured at different wavelengths and depths, and the relations between constraints on the mean intensity of the CIB and its fluctuation spectrum. Consistent with growing evidence that the [approx]1-5 [mu]m mean intensity of the CIB may not be as far above the integrated emission of resolved galaxies as has been reported in some analyses of DIRBE and IRTS observations, our measurements of spatial fluctuations of the CIB intensity indicate the mean emission from the objects producing the fluctuations is quite low ([greater, similar]1 nW m-2 sr-1 at 3-5 [mu]m), and thus consistent with current [gamma]-ray absorption constraints. The source of the fluctuations may be high-z Population III objects, or a more local component of very low luminosity objects with clustering properties that differ from the resolved galaxies. Finally, we discuss the prospects of the upcoming space-based surveys to directly measure the epochs

  2. Learning from concurrent Lightning Imaging Sensor and Lightning Mapping Array observations in preparation for the MTG-LI mission

    Science.gov (United States)

    Defer, Eric; Bovalo, Christophe; Coquillat, Sylvain; Pinty, Jean-Pierre; Farges, Thomas; Krehbiel, Paul; Rison, William

    2016-04-01

    The upcoming decade will see the deployment and the operation of French, European and American space-based missions dedicated to the detection and the characterization of the lightning activity on Earth. For instance the Tool for the Analysis of Radiation from lightNIng and Sprites (TARANIS) mission, with an expected launch in 2018, is a CNES mission dedicated to the study of impulsive energy transfers between the atmosphere of the Earth and the space environment. It will carry a package of Micro Cameras and Photometers (MCP) to detect and locate lightning flashes and triggered Transient Luminous Events (TLEs). At the European level, the Meteosat Third Generation Imager (MTG-I) satellites will carry in 2019 the Lightning Imager (LI) aimed at detecting and locating the lightning activity over almost the full disk of Earth as usually observed with Meteosat geostationary infrared/visible imagers. The American community plans to operate a similar instrument on the GOES-R mission for an effective operation in early 2016. In addition NASA will install in 2016 on the International Space Station the spare version of the Lightning Imaging Sensor (LIS) that has proved its capability to optically detect the tropical lightning activity from the Tropical Rainfall Measuring Mission (TRMM) spacecraft. We will present concurrent observations recorded by the optical space-borne Lightning Imaging Sensor (LIS) and the ground-based Very High Frequency (VHF) Lightning Mapping Array (LMA) for different types of lightning flashes. The properties of the cloud environment will also be considered in the analysis thanks to coincident observations of the different TRMM cloud sensors. The characteristics of the optical signal will be discussed according to the nature of the parent flash components and the cloud properties. This study should provide some insights not only on the expected optical signal that will be recorded by LI, but also on the definition of the validation strategy of LI, and

  3. Comparison of pelvic phased-array versus endorectal coil magnetic resonance imaging at 3 Tesla for local staging of prostate cancer.

    Science.gov (United States)

    Kim, Bum Soo; Kim, Tae-Hwan; Kwon, Tae Gyun; Yoo, Eun Sang

    2012-05-01

    Several studies have demonstrated the superiority of endorectal coil magnetic resonance imaging (MRI) over pelvic phased-array coil MRI at 1.5 Tesla for local staging of prostate cancer. However, few have studied which evaluation is more accurate at 3 Tesla MRI. In this study, we compared the accuracy of local staging of prostate cancer using pelvic phased-array coil or endorectal coil MRI at 3 Tesla. Between January 2005 and May 2010, 151 patients underwent radical prostatectomy. All patients were evaluated with either pelvic phased-array coil or endorectal coil prostate MRI prior to surgery (63 endorectal coils and 88 pelvic phased-array coils). Tumor stage based on MRI was compared with pathologic stage. We calculated the specificity, sensitivity and accuracy of each group in the evaluation of extracapsular extension and seminal vesicle invasion. Both endorectal coil and pelvic phased-array coil MRI achieved high specificity, low sensitivity and moderate accuracy for the detection of extracapsular extension and seminal vesicle invasion. There were statistically no differences in specificity, sensitivity and accuracy between the two groups. Overall staging accuracy, sensitivity and specificity were not significantly different between endorectal coil and pelvic phased-array coil MRI.

  4. Heterodyne detection at 300 GHz using neon indicator lamp glow discharge detector.

    Science.gov (United States)

    Aharon Akram, Avihai; Rozban, Daniel; Kopeika, Natan S; Abramovich, Amir

    2013-06-10

    A miniature neon indicator lamp, also known as a glow discharge detector (GDD), costing about 50 cents, was found to be an excellent room temperature terahertz radiation detector. Proof-of-concept 300 GHz heterodyne detection using GDD is demonstrated in this paper. Furthermore, a comparison to direct detection was carried out as well. Previous results with the GDD at 10 GHz showed 40 times better sensitivity using heterodyne detection compared to direct detection. Preliminary results at 300 GHz showed better sensitivity by a factor of 20 with only 56 μW local-oscillator power using heterodyne compared to direct detection. The higher the local-oscillator power (P(lo)), the better the sensitivity of the detector. Further improvement can be achieved by employing better quasi-optical design.

  5. Operating scheme for the light-emitting diode array of a volumetric display that exhibits multiple full-color dynamic images

    Science.gov (United States)

    Hirayama, Ryuji; Shiraki, Atsushi; Nakayama, Hirotaka; Kakue, Takashi; Shimobaba, Tomoyoshi; Ito, Tomoyoshi

    2017-07-01

    We designed and developed a control circuit for a three-dimensional (3-D) light-emitting diode (LED) array to be used in volumetric displays exhibiting full-color dynamic 3-D images. The circuit was implemented on a field-programmable gate array; therefore, pulse-width modulation, which requires high-speed processing, could be operated in real time. We experimentally evaluated the developed system by measuring the luminance of an LED with varying input and confirmed that the system works appropriately. In addition, we demonstrated that the volumetric display exhibits different full-color dynamic two-dimensional images in two orthogonal directions. Each of the exhibited images could be obtained only from the prescribed viewpoint. Such directional characteristics of the system are beneficial for applications, including digital signage, security systems, art, and amusement.

  6. Single-side access, isotropic resolution and multispectral 3D photoacoustic imaging with rotate-translate scanning of ultrasonic detector array

    CERN Document Server

    Gateau, Jérôme; Chassot, Jean-Marie; Bossy, Emmanuel

    2015-01-01

    Photoacoustic imaging can achieve high-resolution three-dimensional visualization of optical absorbers at penetration depths ~ 1 cm in biological tissues by detecting optically-induced high ultrasound frequencies. Tomographic acquisition with ultrasound linear arrays offers an easy implementation of single-side access, parallelized and high-frequency detection, but usually comes with an image quality impaired by the directionality of the detectors. Indeed, a simple translation of the array perpendicularly to its median imaging plane is often used, but results both in a poor resolution in the translation direction and in strong limited view artifacts. To improve the spatial resolution and the visibility of complex structures while keeping a planar detection geometry, we introduce, in this paper, a novel rotate-translate scanning scheme, and investigate the performance of a scanner implemented at 15 MHz center frequency. The developed system achieved a quasi-isotropic uniform 3D resolution of ~170 um over a cub...

  7. Comparison of Pelvic Phased-Array versus Endorectal Coil Magnetic Resonance Imaging at 3 Tesla for Local Staging of Prostate Cancer

    OpenAIRE

    Kim, Bum Soo; Kim, Tae-Hwan; Kwon, Tae Gyun; Yoo, Eun Sang

    2012-01-01

    Purpose Several studies have demonstrated the superiority of endorectal coil magnetic resonance imaging (MRI) over pelvic phased-array coil MRI at 1.5 Tesla for local staging of prostate cancer. However, few have studied which evaluation is more accurate at 3 Tesla MRI. In this study, we compared the accuracy of local staging of prostate cancer using pelvic phased-array coil or endorectal coil MRI at 3 Tesla. Materials and Methods Between January 2005 and May 2010, 151 patients underwent radi...

  8. An Indium Gallium Arsenide Visible/SWIR Focal Plane Array for Low Light Level Imaging

    Science.gov (United States)

    Cohen, Marshall J.; Ettenberg, Martin H.; Lange, Michael J.; Olsen, Gregory H.

    1999-01-01

    PIN photodiodes fabricated from indium gallium arsenide lattice-matched to indium phosphide substrates (In(.53)Ga(.47)As/InP) exhibit low reverse saturation current densities (JD 10(exp 6) omega-sq cm) at T=290K. Backside-illuminated, hybrid-integrated InGaAs FPAs are sensitive from 0.9 micrometers to 1.7 micrometers. 290K detectivities, D(*), greater than 10(exp 14) cm-(square root of Hz/W) are demonstrated. This represents the highest room temperature detectivity of any infrared material. The long wavelength cutoff (1.7 micrometers) makes In(.53)Ga(.47)As an idea match to the available airglow that has major peaks at 1.3 micrometers and 1.6 micrometers. The short wavelength 'cut-on' at 0.9 micrometers is due to absorption in the InP substrate. We will report on new InGaAs FPA epitaxial structures and processing techniques. These have resulted in improved performance in the form of a 10 x increase in detectivity and visible response via removal of the InP substrate. The resulting device features visible and SWIR response with greater than 15% quantum efficiency at 0.5 micrometers while maintaining the long wavelength cutoff. Imaging has been demonstrated under overcast starlight/urban glow conditions with cooling provided by a single stage thermoelectric cooler. Details on the material structure and device fabrication, quantitative characterization of spectral response and detectivity, as well as examples of night vision imagery are presented.

  9. Usefulness of the infrared heterodyne radiometer in remote sensing of atmospheric pollutants.

    Science.gov (United States)

    Menzies, R. T.; Shumate, M. S.

    1971-01-01

    The application of narrow-band optical receivers to the problem of sensing atmospheric pollution is discussed. The emission/absorption lines of many major atmospheric pollutant molecules overlap the operating frequency bands of CO2 laser and CO laser heterodyne receivers. Several remote pollution sensing systems which are based upon utilization of these spectral overlaps are described, and an analysis of their potential is presented. The possibility of using other lasers (e.g.: the PbSnTe tunable diode laser) as local oscillators is also considered. Results of laboratory experiments with a CO2 laser heterodyne radiometer are presented.

  10. Renal magnetic resonance angiography at 3.0 Tesla using a 32-element phased-array coil system and parallel imaging in 2 directions.

    Science.gov (United States)

    Fenchel, Michael; Nael, Kambiz; Deshpande, Vibhas S; Finn, J Paul; Kramer, Ulrich; Miller, Stephan; Ruehm, Stefan; Laub, Gerhard

    2006-09-01

    The aim of the present study was to assess the feasibility of renal magnetic resonance angiography at 3.0 T using a phased-array coil system with 32-coil elements. Specifically, high parallel imaging factors were used for an increased spatial resolution and anatomic coverage of the whole abdomen. Signal-to-noise values and the g-factor distribution of the 32 element coil were examined in phantom studies for the magnetic resonance angiography (MRA) sequence. Eleven volunteers (6 men, median age of 30.0 years) were examined on a 3.0-T MR scanner (Magnetom Trio, Siemens Medical Solutions, Malvern, PA) using a 32-element phased-array coil (prototype from In vivo Corp.). Contrast-enhanced 3D-MRA (TR 2.95 milliseconds, TE 1.12 milliseconds, flip angle 25-30 degrees , bandwidth 650 Hz/pixel) was acquired with integrated generalized autocalibrating partially parallel acquisition (GRAPPA), in both phase- and slice-encoding direction. Images were assessed by 2 independent observers with regard to image quality, noise and presence of artifacts. Signal-to-noise levels of 22.2 +/- 22.0 and 57.9 +/- 49.0 were measured with (GRAPPAx6) and without parallel-imaging, respectively. The mean g-factor of the 32-element coil for GRAPPA with an acceleration of 3 and 2 in the phase-encoding and slice-encoding direction, respectively, was 1.61. High image quality was found in 9 of 11 volunteers (2.6 +/- 0.8) with good overall interobserver agreement (k = 0.87). Relatively low image quality with higher noise levels were encountered in 2 volunteers. MRA at 3.0 T using a 32-element phased-array coil is feasible in healthy volunteers. High diagnostic image quality and extended anatomic coverage could be achieved with application of high parallel imaging factors.

  11. A transmit/receive radiofrequency array for imaging the carotid arteries at 7 Tesla: coil design and first in vivo results.

    Science.gov (United States)

    Kraff, Oliver; Bitz, Andreas K; Breyer, Tobias; Kruszona, Stefan; Maderwald, Stefan; Brote, Irina; Gizewski, Elke R; Ladd, Mark E; Quick, Harald H

    2011-04-01

    To develop a transmit/receive radiofrequency (RF) array for magnetic resonance imaging (MRI) of the carotid arteries at 7 T. The prototype is characterized in numerical simulations and bench measurements, and the feasibility of plaque imaging at 7 T is demonstrated in first in vivo images. The RF phased array coil consists of 8 surface loop coils. To allow imaging of both sides of the neck, the RF array is divided into 2 coil clusters, each with 4 overlapping loop elements. For safety validation, numerical computations of the RF field distribution and the corresponding specific absorption rate were performed on the basis of a heterogeneous human body model. To validate the coil model, maps of the transmit B1(+) field were compared between simulation and measurement. In vivo images of a healthy volunteer and a patient (ulcerating plaque and a 50% stenosis of the right internal carotid artery) were acquired using a 3-dimensional FLASH sequence with a high isotropic spatial resolution of 0.54 mm as well as using pulse-triggered proton density (PD)/T2-weighted turbo spin echo sequences. Measurements of the S-parameters yielded a reflection and isolation of the coil elements of better than -18 and -13 dB, respectively. Measurements of the g-factor indicated good image quality for parallel imaging acceleration factors up to 2.4. A similar distribution and a very good match of the absolute values were found between the measured and simulated B1(+) transmit RF field for the validation of the coil model. In vivo images revealed good signal excitation of both sides of the neck and a high vessel-to-background image contrast for the noncontrast-enhanced 3-dimensional FLASH sequence. Imaging at 7 T could depict the extent of stenosis, and revealed the disruption and ulcer of the plaque. This study demonstrates that 2 four-channel transmit/receive RF arrays for each side of the neck is a suitable concept for in vivo MRI of the carotid arteries at 7 Tesla. Further studies are

  12. Final report on LDRD project : single-photon-sensitive imaging detector arrays at 1600 nm.

    Energy Technology Data Exchange (ETDEWEB)

    Childs, Kenton David; Serkland, Darwin Keith; Geib, Kent Martin; Hawkins, Samuel D.; Carroll, Malcolm S.; Klem, John Frederick; Sheng, Josephine Juin-Jye; Patel, Rupal K.; Bolles, Desta; Bauer, Tom M.; Koudelka, Robert

    2006-11-01

    The key need that this project has addressed is a short-wave infrared light detector for ranging (LIDAR) imaging at temperatures greater than 100K, as desired by nonproliferation and work for other customers. Several novel device structures to improve avalanche photodiodes (APDs) were fabricated to achieve the desired APD performance. A primary challenge to achieving high sensitivity APDs at 1550 nm is that the small band-gap materials (e.g., InGaAs or Ge) necessary to detect low-energy photons exhibit higher dark counts and higher multiplication noise compared to materials like silicon. To overcome these historical problems APDs were designed and fabricated using separate absorption and multiplication (SAM) regions. The absorption regions used (InGaAs or Ge) to leverage these materials 1550 nm sensitivity. Geiger mode detection was chosen to circumvent gain noise issues in the III-V and Ge multiplication regions, while a novel Ge/Si device was built to examine the utility of transferring photoelectrons in a silicon multiplication region. Silicon is known to have very good analog and GM multiplication properties. The proposed devices represented a high-risk for high-reward approach. Therefore one primary goal of this work was to experimentally resolve uncertainty about the novel APD structures. This work specifically examined three different designs. An InGaAs/InAlAs Geiger mode (GM) structure was proposed for the superior multiplication properties of the InAlAs. The hypothesis to be tested in this structure was whether InAlAs really presented an advantage in GM. A Ge/Si SAM was proposed representing the best possible multiplication material (i.e., silicon), however, significant uncertainty existed about both the Ge material quality and the ability to transfer photoelectrons across the Ge/Si interface. Finally a third pure germanium GM structure was proposed because bulk germanium has been reported to have better dark count properties. However, significant

  13. 3-D Imaging Using Row–Column-Addressed Arrays With Integrated Apodization. Part I: Apodization Design and Line Element Beamforming

    DEFF Research Database (Denmark)

    Rasmussen, Morten Fischer; Christiansen, Thomas Lehrmann; Thomsen, Erik Vilain

    2015-01-01

    This paper investigates the effect of transducerintegrated apodization in row–column-addressed arrays and presents a beamforming approach specific for such arrays. Row–column addressing 2-D arrays greatly reduces the number of active channels needed to acquire a 3-D volume. A disadvantage of row–....... In Part II of this work, experimental results from a capacitive micromachined ultrasonic transducer with integrated roll-off apodization are given to validate the effect of integrating apodization into the line elements....

  14. Imaging Ionospheric/Plasmaspheric Disturbances Triggered by the 2017 Total Solar Eclipse with the Very Large Array

    Science.gov (United States)

    Helmboldt, Joseph; Schinzel, Frank K.; VLA Low-band Ionosphere and Transient Experiment (VLITE)

    2018-01-01

    Along with many Americans and several other observatories, the Karl G. Jansky Very Large Array (VLA) was observing the Sun before, during, and after the total solar eclipse on 21 August 2017. However, the VLA also simultaneously conducted a unique set of observations aimed at characterizing the effects of the eclipse on Earth’s ionosphere/plasmasphere. While most of the VLA antennas were pointed at the Sun, 12 were looking at the bright radio galaxy M87. These 12 antennas are part of the VLA Low-band Ionosphere and Transient Experiment (VLITE; http://vlite.nrao.edu), a dedicated backend that continuously captures, correlates, and analyzes data in the 320-384 MHz frequency range. In addition to traditional synthesis imaging, VLITE also characterizes fluctuations in ionospheric/plasmaspheric density via measured variations in visibility phases. When observing a bright cosmic source, this can be done with unmatched precision, the equivalent of ~1-10 ppm. To look for ionospheric/plasmaspheric disturbances tied to the eclipse, a specialized spectral decomposition was applied to the M87 VLITE data. This method exploits the fact that disturbed flux tubes within the plasmasphere appear as magnetic eastward-directed waves to the VLA because the plasmasphere is dynamically dominated by co-rotation. The phase speeds of these waves are proportional to distance, allowing for a reconstruction of the electron density gradient as a function of (slant) range and time. The time ranges spanned by the large-scale ionospheric depletion seen within concurrent Global Positioning System (GPS) data as a function of longitude were mapped to the flux tubes imaged with this method using the M87 observations. With the exception of some solar flare-induced fluctuations, the observed disturbances appear confined to this part of the range/time image. This strongly implies the disturbances resulted from the rapid depletion and slower recovery of the ionosphere/plasmasphere system brought on by

  15. Characterizing thawing permafrost with the Miniaturized Laser Heterodyne Radiometer (mini-LHR) through column measurements of methane

    Science.gov (United States)

    Wilson, E. L.; DiGregorio, A.

    2015-12-01

    We present mini-LHR measurements of column CH4 from our preliminary field campaign outside of Fairbanks, AK in June 2015. The mini-LHR is fully automated and works in tandem with the AERONET sun photometer for collection of column CH4 every 15 minutes. As part of a comprehensive array of ground based instruments, measurements made by the mini-LHR will aid in monitoring of changes in atmospheric greenhouse gas emissions and help interpret data collected by space-born instruments. The mini-LHR is a passive variation of typical heterodyne radiometry instruments, using sunlight as the light source for measuring CH4 in the infrared. Collecting through collimation optics mounted on the AERONET tracker, the sunlight is chopped in an optical chopper and mixed with a local oscillator in a fast photoreciever (InGaAs detector). The amplitude of the resultant RF (radio frequency) beat signal directly correlates with the concentration of the column gas being measured. Working in conjunction with ground penetrating radar, covariance flux tower, and high-resolution surface CO2 and CH4 measurements, our column CH4 measurements contribute to a holistic view of the atmospheric evolution and response to permafrost thaw. With the intent to expand our observational network to other North American sites, our column CH4 measurements will be instrumental in showing the effects of permafrost thaw on global CH4 levels, as well as benefiting ongoing efforts in retrospective and predictive simulations of greenhouse gasses.

  16. Development of a 400 Level 3C Clamped Downhole Seismic Receiver Array for 3D Borehole Seismic Imaging of Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Bjorn N. P. Paulsson

    2006-09-30

    Borehole seismology is the highest resolution geophysical imaging technique available today to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to perform high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology has been hampered by the lack of acquisition technology necessary to record large volumes of high frequency, high signal-to-noise-ratio borehole seismic data. This project took aim at this shortcoming by developing a 400 level 3C clamped downhole seismic receiver array, and accompanying software, for borehole seismic 3D imaging. This large borehole seismic array has removed the technical acquisition barrier for recording the data volumes necessary to do high resolution 3D VSP and 3D cross-well seismic imaging. Massive 3D VSP{reg_sign} and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that promise to take the gas industry to the next level in their quest for higher resolution images of deep and complex oil and gas reservoirs. Today only a fraction of the oil or gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of detailed compartmentalization of oil and gas reservoirs. In this project, we developed a 400 level 3C borehole seismic receiver array that allows for economic use of 3D borehole seismic imaging for reservoir characterization and monitoring. This new array has significantly increased the efficiency of recording large data volumes at sufficiently dense spatial sampling to resolve reservoir complexities. The receiver pods have been fabricated and tested to withstand high temperature (200 C/400 F) and high pressure (25,000 psi), so that they can operate in wells up to 7,620 meters (25,000 feet) deep. The receiver array is deployed on standard production or drill tubing. In combination with 3C surface seismic or 3C borehole seismic sources, the 400

  17. Single scan parameterization of space-variant point spread functions in image space via a printed array: the impact for two PET/CT scanners

    Energy Technology Data Exchange (ETDEWEB)

    Kotasidis, F A; Matthews, J C; Angelis, G I; Noonan, P J; Jackson, A [Imaging, Genomics and Proteomics, Wolfson Molecular Imaging Centre, MAHSC, University of Manchester, Manchester (United Kingdom); Price, P [Academic Department of Radiation Oncology, University of Manchester, Manchester (United Kingdom); Lionheart, W R [School of Mathematics, Alan Turing Building, University of Manchester, Manchester (United Kingdom); Reader, A J, E-mail: fotis.kotasidis@mmic.man.ac.uk [Brain Imaging Centre, Montreal Neurological Institute, McGill University, Montreal, QC (Canada)

    2011-05-21

    Incorporation of a resolution model during statistical image reconstruction often produces images of improved resolution and signal-to-noise ratio. A novel and practical methodology to rapidly and accurately determine the overall emission and detection blurring component of the system matrix using a printed point source array within a custom-made Perspex phantom is presented. The array was scanned at different positions and orientations within the field of view (FOV) to examine the feasibility of extrapolating the measured point source blurring to other locations in the FOV and the robustness of measurements from a single point source array scan. We measured the spatially-variant image-based blurring on two PET/CT scanners, the B-Hi-Rez and the TruePoint TrueV. These measured spatially-variant kernels and the spatially-invariant kernel at the FOV centre were then incorporated within an ordinary Poisson ordered subset expectation maximization (OP-OSEM) algorithm and compared to the manufacturer's implementation using projection space resolution modelling (RM). Comparisons were based on a point source array, the NEMA IEC image quality phantom, the Cologne resolution phantom and two clinical studies (carbon-11 labelled anti-sense oligonucleotide [{sup 11}C]-ASO and fluorine-18 labelled fluoro-l-thymidine [{sup 18}F]-FLT). Robust and accurate measurements of spatially-variant image blurring were successfully obtained from a single scan. Spatially-variant resolution modelling resulted in notable resolution improvements away from the centre of the FOV. Comparison between spatially-variant image-space methods and the projection-space approach (the first such report, using a range of studies) demonstrated very similar performance with our image-based implementation producing slightly better contrast recovery (CR) for the same level of image roughness (IR). These results demonstrate that image-based resolution modelling within reconstruction is a valid alternative to

  18. Terahertz heterodyne mixing with a hot electron bolometer and a quantum cascade laser

    NARCIS (Netherlands)

    Hajenius, M.

    2007-01-01

    Heterodyne measurements in the frequency range between 1 - 6 terahertz (THz) are expected to provide a wealth of information on questions ranging from the formation of new stars and the conditions under which life formed on our own planet to the ozone hole in our own atmosphere. Hot electron

  19. SUBMM heterodyne mixing using NbCN/Nb SIS tunnel junctions.

    NARCIS (Netherlands)

    vandeStadt, H; Mees, J; Barber, Z; Blamire, M; Dieleman, P; deGraauw, T

    We describe heterodyne mixing experiments with NbCN/Nb quasi-particle tunnel junctions at submillimeter wavelengths. In this wavelength range junctions with niobium nitride as superconducting material are promising because of the high gap voltage, about 5.7 mV, as compared to 3 mV for the more

  20. High-resolution heterodyne spectroscopy using a tunable quantum cascade laser around 3.5 THz

    NARCIS (Netherlands)

    Ren, Y.; Hovenier, J.N.; Higgins, R.; Gao, J.R.; Klapwijk, T.M.; Shi, S.C.; Klein, B.; Kao, T.Y.; Hu, Q.; Reno, J.L.

    2011-01-01

    A frequency tunable terahertz heterodyne spectrometer, based on a third-order distributed feedback quantum cascade laser as a local oscillator, has been demonstrated by measuring molecular spectral lines of methanol (CH3OH) gas at 3.5 THz. By varying the bias voltage of the laser, we achieved a

  1. Hydrogen-bond dynamics in water explored by heterodyne-detected photon echo

    NARCIS (Netherlands)

    Yeremenko, S; Pshenichnikov, MS; Wiersma, DA; Pshenichnikov, Maxim S.

    2003-01-01

    Results of heterodyne-detected photon echo experiments on the OH stretching mode of water are reported and discussed. Two vibrational dynamical processes with time constants of 130 and 900 fs were identified. The former is attributed to bond breaking dynamics of a single hydrogen bond, the latter to

  2. Three-Dimensional ISAR Imaging Method for High-Speed Targets in Short-Range Using Impulse Radar Based on SIMO Array

    OpenAIRE

    Zhou, Xinpeng; Wei, Guohua; Wu, Siliang; Wang, Dawei

    2016-01-01

    This paper proposes a three-dimensional inverse synthetic aperture radar (ISAR) imaging method for high-speed targets in short-range using an impulse radar. According to the requirements for high-speed target measurement in short-range, this paper establishes the single-input multiple-output (SIMO) antenna array, and further proposes a missile motion parameter estimation method based on impulse radar. By analyzing the motion geometry relationship of the warhead scattering center after transla...

  3. Caliste 64: detection unit of a spectro imager array for a hard x-ray space telescope

    Science.gov (United States)

    Limousin, O.; Meuris, A.; Lugiez, F.; Gevin, Olivier; Pinsard, F.; Blondel, C.; Le Mer, I.; Delagnes, E.; Vassal, M. C.; Soufflet, F.; Bocage, R.; Penquer, A.; Billot, M.

    2017-11-01

    In the frame of the hard X-ray Simbol-X observatory, a joint CNES-ASI space mission to be flown in 2014, a prototype of miniature Cd(Zn)Te camera equipped with 64 pixels has been designed. The device, called Caliste 64, is a spectro-imager with high resolution event timetagging capability. Caliste 64 integrates a Cd(Zn)Te semiconductor detector with segmented electrode and its front-end electronics made of 64 independent analog readout channels. This 1 × 1 × 2 cm3 camera, able to detect photons in the range from 2 keV up to 250 keV, is an elementary detection unit juxtaposable on its four sides. Consequently, large detector array can be made assembling a mosaic of Caliste 64 units. Electronics readout module is achieved by stacking four IDeF-X V1.1 ASICs, perpendicular to the detection plane. We achieved good noise performances, with a mean Equivalent Noise Charge of 65 electrons rms over the 64 channels. For the first prototypes, we chose Pt//CdTe//Al/Ti/Au Schottky detectors because of their very low dark current and excellent spectroscopic performances. Recently a Caliste 64 prototype has been also equipped with a 2 mm thick Au//CdZnTe//Au detector. This paper presents the performances of these four prototypes and demonstrates spectral performances better than 1 keV fwhm at 59.54 keV when the samples are moderately cooled down to -10°C.

  4. Advancement and New Optimizations of Microcalorimeter Arrays for High-Resolution Imaging X-ray Spectroscopy Project

    Data.gov (United States)

    National Aeronautics and Space Administration — "We propose to continue our successful research program in developing x-ray microcalorimeter arrays for astrophysics. This development will directly benefit not only...

  5. New compact and efficient local oscillator optic system for the KSTAR electron cyclotron emission imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Y. B., E-mail: southub@postech.ac.kr; Yun, G. S. [Department of Physics, Pohang University of Science and Technology, Pohang 37673 (Korea, Republic of); Lee, D. J.; Lee, J.; Lee, W. [Ulsan National Institute of Science and Technology, Ulsan 44919 (Korea, Republic of); Kim, C. [Pennsylvania State University, Old Main, State College, Pennsylvania 16801 (United States); Park, H. K. [Ulsan National Institute of Science and Technology, Ulsan 44919 (Korea, Republic of); National Fusion Research Institute, Daejeon 34133 (Korea, Republic of)

    2016-11-15

    Electron cyclotron emission imaging (ECEI) diagnostic on Korean Superconducting Tokamak Advanced Research utilizes quasi-optical heterodyne-detection method to measure 2D (vertical and radial) T{sub e} fluctuations from two toroidally separated poloidal cross section of the plasma. A cylindrical lens local oscillator (LO) optics with optical path length (OPL) 2–2.5 m has been used in the current ECEI system to couple the LO source to the 24 vertically aligned array of ECE detectors. For efficient and compact LO optics employing the Powell lens is proposed so that the OPL of the LO source is significantly reduced from ∼2.0 m to 0.4 m with new optics. The coupling efficiency of the LO source is expected to be improved especially at the edge channels. Results from the optical simulation together with the laboratory test of the prototype optics will be discussed in this paper.

  6. Double-heterodyne-interferometry with delay-lines larger than coherence length of the laser light used

    Science.gov (United States)

    Hofbauer, Ulrich; Dalhoff, Ernst; Tiziani, Hans

    1999-04-01

    A double-heterodyne-interferometer (DHI) was realized with a laser diode as light source and a 500-MHz acoustooptical modulator (AOM). We show that measurements of the phase between the two heterodyne signals at optical path differences (OPD) up to 3.25 km, which is more than 350 times the coherence length of the laser light used, are possible. By measurements with this delay line, a distance resolution of 0.14 mm was obtained.

  7. Multicolor, time-gated, soft x-ray pinhole imaging of wire array and gas puff Z pinches on the Z and Saturn pulsed power generators.

    Science.gov (United States)

    Jones, B; Coverdale, C A; Nielsen, D S; Jones, M C; Deeney, C; Serrano, J D; Nielsen-Weber, L B; Meyer, C J; Apruzese, J P; Clark, R W; Coleman, P L

    2008-10-01

    A multicolor, time-gated, soft x-ray pinhole imaging instrument is fielded as part of the core diagnostic set on the 25 MA Z machine [M. E. Savage et al., in Proceedings of the Pulsed Power Plasma Sciences Conference (IEEE, New York, 2007), p. 979] for studying intense wire array and gas puff Z-pinch soft x-ray sources. Pinhole images are reflected from a planar multilayer mirror, passing 277 eV photons with Saturn generator [R. B. Spielman et al., and A. I. P. Conf, Proc. 195, 3 (1989)] for imaging a bright Li-like Ar L-shell line. Ar gas puff Z pinches show an intense K-shell emission from a zippering stagnation front with L-shell emission dominating as the plasma cools.

  8. Large-scale, high-resolution electrophysiological imaging of field potentials in brain slices with microelectronic multielectrode arrays.

    Science.gov (United States)

    Ferrea, E; Maccione, A; Medrihan, L; Nieus, T; Ghezzi, D; Baldelli, P; Benfenati, F; Berdondini, L

    2012-01-01

    Multielectrode arrays (MEAs) are extensively used for electrophysiological studies on brain slices, but the spatial resolution and field of recording of conventional arrays are limited by the low number of electrodes available. Here, we present a large-scale array recording simultaneously from 4096 electrodes used to study propagating spontaneous and evoked network activity in acute murine cortico-hippocampal brain slices at unprecedented spatial and temporal resolution. We demonstrate that multiple chemically induced epileptiform episodes in the mouse cortex and hippocampus can be classified according to their spatio-temporal dynamics. Additionally, the large-scale and high-density features of our recording system enable the topological localization and quantification of the effects of antiepileptic drugs in local neuronal microcircuits, based on the distinct field potential propagation patterns. This novel high-resolution approach paves the way to detailed electrophysiological studies in brain circuits spanning spatial scales from single neurons up to the entire slice network.

  9. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2013-01-01

    Radar Techniques Using Array Antennas is a thorough introduction to the possibilities of radar technology based on electronic steerable and active array antennas. Topics covered include array signal processing, array calibration, adaptive digital beamforming, adaptive monopulse, superresolution, pulse compression, sequential detection, target detection with long pulse series, space-time adaptive processing (STAP), moving target detection using synthetic aperture radar (SAR), target imaging, energy management and system parameter relations. The discussed methods are confirmed by simulation stud

  10. Voltage tunable differential heterodyne spectroscopy in the far-infrared with Josephson junctions

    Science.gov (United States)

    Ulrich, B. T.

    1978-01-01

    The basic methods of differential heterodyne spectroscopy with Josephson junctions are described. A technique is outlined for bridging the gap between a local oscillator frequency and a signal frequency through the use of a voltage-tunable internal oscillation frequency in a Josephson junction structure. It is shown that an intermediate frequency can be converted to a conveniently low frequency by double frequency conversion carried out directly in a Josephson junction. The expected conversion efficiency is estimated qualitatively. Experiments are discussed in which the differential heterodyne frequency-conversion technique was demonstrated at a wavelength of 0.4 mm and a voltage-tunable oscillation in a double Josephson junction structure was observed, with oscillation line widths as narrow as 0.5 Hz, for a resistance of 3.3 nanohms and an estimated inductance of the order of 1 nH.

  11. A Miniaturized Laser Heterodyne Radiometer for Greenhouse Gas Measurements in the Atmospheric Column

    Science.gov (United States)

    Steel, Emily Wilson

    2015-01-01

    Laser Heterodyne Radiometry is a technique adapted from radio receiver technology has been used to measure trace gases in the atmosphere since the 1960s.By leveraging advances in the telecommunications industry, it has been possible to miniaturize this technology.The mini-LHR (Miniaturized Laser Heterodyne Radiometer) has been under development at NASA Goddard Space flight Center since 2009. This sun-viewing instrument measures carbon dioxide and methane in the atmospheric column and operates in tandem with an AERONET sun photometer producing a simultaneous measure of aerosols. The mini-LHR has been extensively field tested in a range of locations ranging in the continental US as well as Alaska and Hawaii and now operates autonomously with sensitivities of approximately 0.2 ppmv and approximately10 ppbv, for carbon dioxide and methane respectively, for 10 averaged scans under clear sky conditions.

  12. Experimental study on the 1550 nm all fiber heterodyne laser range finder.

    Science.gov (United States)

    Yang, Fu; He, Yan; Shang, Jianhua; Chen, Weibiao

    2009-12-01

    In this paper, a 1550 nm all fiber monostatic laser range finder system based on linear chirp modulation and heterodyne detection is presented. The fiber end face signal is used as a range starting indicator. The transmitted laser power is 5 mW with a laser pulse length of 131 micros and a linear chirp bandwidth of 40 MHz. The telescope with an aperture of 3 cm couples the return light into a single mode fiber. Better than 14 cm distance accuracy and 26 dB SNR can be achieved for a wood target at a distance of about 43 m by using the above system setup. Several experiments with different system parameters are conducted. The system performance is tested under variable laser pulse length, linear chirp bandwidth, local oscillator power, and background noise. Finally, an application of the linear chirp modulation heterodyne laser range finder in a spaceborne ranging system is proposed.

  13. Heterodyne lock-in thermography of early demineralized in dental tissues

    Science.gov (United States)

    Wang, Fei; Liu, Jun-yan; Mohummad, Oliullah; Wang, Xiao-chun; Wang, Yang

    2017-12-01

    Heterodyne lock-in thermography (HeLIT) is a highly sensitive method to detect early demineralized in dental tissues, which is based on nonlinear photothermal phenomena of dental tissues. In this paper, the nonlinear photothermal phenomena of dental tissues was introduced, and then the system of HeLIT was developed. The relationship between laser modulated parameters (modulated frequency and laser intensity) and heterodyne lock-in thermal wave signal was investigated. The comparison between HeLIT and homodyne lock-in thermography (HoLIT) for detecting the different types of dental caries (smooth surface caries, proximal surface caries and occlusal surface caries) were carried out. Experimental results illustrate that the HeLIT has the merits of high sensitivity and high specificity in detecting different types of early caries.

  14. Signal-to-noise ratio and MR tissue parameters in human brain imaging at 3, 7, and 9.4 tesla using current receive coil arrays.

    Science.gov (United States)

    Pohmann, Rolf; Speck, Oliver; Scheffler, Klaus

    2016-02-01

    Relaxation times, transmit homogeneity, signal-to-noise ratio (SNR) and parallel imaging g-factor were determined in the human brain at 3T, 7T, and 9.4T, using standard, tight-fitting coil arrays. The same human subjects were scanned at all three field strengths, using identical sequence parameters and similar 31- or 32-channel receive coil arrays. The SNR of three-dimensional (3D) gradient echo images was determined using a multiple replica approach and corrected with measured flip angle and T2 (*) distributions and the T1 of white matter to obtain the intrinsic SNR. The g-factor maps were derived from 3D gradient echo images with several GRAPPA accelerations. As expected, T1 values increased, T2 (*) decreased and the B1 -homogeneity deteriorated with increasing field. The SNR showed a distinctly supralinear increase with field strength by a factor of 3.10 ± 0.20 from 3T to 7T, and 1.76 ± 0.13 from 7T to 9.4T over the entire cerebrum. The g-factors did not show the expected decrease, indicating a dominating role of coil design. In standard experimental conditions, SNR increased supralinearly with field strength (SNR ∼ B0 (1.65) ). To take full advantage of this gain, the deteriorating B1 -homogeneity and the decreasing T2 (*) have to be overcome. © 2015 Wiley Periodicals, Inc.

  15. Laser-diode interferometric heterodyne vibrometer: application to linear motor control.

    Science.gov (United States)

    Chebbour, A; Gharbi, T; Tribillon, G

    2001-11-01

    We describe an interferometric heterodyne vibrometer that uses a laser diode with a triangular modulation frequency. This optical sensor is used to probe a vibrating polished surface. As an illustration of the sensor performance, the control of nonuniform velocity of a linear motor is achieved. The technique can be used over a large bandwidth between a few hertz and several tens of kilohertz. Generalization of the technique to the sensing of frequency vibrations is also demonstrated theoretically.

  16. Study of optical nonlinearity of a highly dispersive medium using optical heterodyne detection technique

    CERN Document Server

    Bhowmick, Arup; Mohapatra, Ashok K

    2016-01-01

    We discuss the optical heterodyne detection technique to study the absorption and dispersion of a probe beam propagating through a medium with a narrow resonance. The technique has been demonstrated for Rydberg Electro-magnetically induced transparency (EIT) in rubidium thermal vapor and the optical non-linearity of a probe beam with variable intensity has been studied. A quantitative comparison of the experimental result with a suitable theoretical model is presented. The limitations and the working regime of the technique are discussed.

  17. Dielectric Covered Planar Antennas at Submillimeter Wavelengths for Terahertz Imaging

    Science.gov (United States)

    Chattopadhyay, Goutam; Gill, John J.; Skalare, Anders; Lee, Choonsup; Llombart, Nuria; Siegel, Peter H.

    2011-01-01

    Most optical systems require antennas with directive patterns. This means that the physical area of the antenna will be large in terms of the wavelength. When non-cooled systems are used, the losses of microstrip or coplanar waveguide lines impede the use of standard patch or slot antennas for a large number of elements in a phased array format. Traditionally, this problem has been solved by using silicon lenses. However, if an array of such highly directive antennas is to be used for imaging applications, the fabrication of many closely spaced lenses becomes a problem. Moreover, planar antennas are usually fed by microstrip or coplanar waveguides while the mixer or the detector elements (usually Schottky diodes) are coupled in a waveguide environment. The coupling between the antenna and the detector/ mixer can be a fabrication challenge in an imaging array at submillimeter wavelengths. Antennas excited by a waveguide (TE10) mode makes use of dielectric superlayers to increase the directivity. These antennas create a kind of Fabry- Perot cavity between the ground plane and the first layer of dielectric. In reality, the antenna operates as a leaky wave mode where a leaky wave pole propagates along the cavity while it radiates. Thanks to this pole, the directivity of a small antenna is considerably enhanced. The antenna consists of a waveguide feed, which can be coupled to a mixer or detector such as a Schottky diode via a standard probe design. The waveguide is loaded with a double-slot iris to perform an impedance match and to suppress undesired modes that can propagate on the cavity. On top of the slot there is an air cavity and on top, a small portion of a hemispherical lens. The fractional bandwidth of such antennas is around 10 percent, which is good enough for heterodyne imaging applications.The new geometry makes use of a silicon lens instead of dielectric quarter wavelength substrates. This design presents several advantages when used in the submillimeter

  18. X-ray imager using solution processed organic transistor arrays and bulk heterojunction photodiodes on thin, flexible plastic substrate

    NARCIS (Netherlands)

    Gelinck, G.H.; Kumar, A.; Moet, D.; Steen, J.L. van der; Shafique, U.; Malinowski, P.E.; Myny, K.; Rand, B.P.; Simon, M.; Rütten, W.; Douglas, A.; Jorritsma, J.; Heremans, P.L.; Andriessen, H.A.J.M.

    2013-01-01

    We describe the fabrication and characterization of large-area active-matrix X-ray/photodetector array of high quality using organic photodiodes and organic transistors. All layers with the exception of the electrodes are solution processed. Because it is processed on a very thin plastic substrate

  19. A magnetic resonance imaging-compatible, large-scale array for trans-skull ultrasound surgery and therapy.

    Science.gov (United States)

    Clement, Gregory T; White, P Jason; King, Randy L; McDannold, Nathan; Hynynen, Kullervo

    2005-08-01

    Advances in ultrasound transducer array and amplifier technologies have prompted many intriguing scientific proposals for ultrasound therapy. These include both mildly invasive and noninvasive techniques to be used in ultrasound brain surgery through the skull. In previous work, it was shown how a 500-element hemisphere-shaped transducer could correct the wave distortion caused by the skull with a transducer that operates at a frequency near 0.8 MHz. Because the objective for trans-skull focusing is its ultimate use in a clinical context, a new hemispheric phased-array system has now been developed with acoustic parameters that are optimized to match the values determined in preliminary studies. The transducer was tested by focusing ultrasound through ex vivo human skulls and into a brain phantom by means of a phase-adaptive focusing technique. Simultaneously, the procedure was monitored by the use of magnetic resonance guidance and thermometry. The ultrasound focus of a 500-element 30-cm-diameter, 0.81-MHz array could be steered electronically through the skull over a volume of approximately 30 x 30 x 26 mm. Furthermore, temperature monitoring of the inner and outer surfaces of the skull showed that the array could coagulate targeted brain tissue without causing excessive skull heating. The successful outcome of these experiments indicates that intensities high enough to destroy brain tissue can be produced without excessive heating of the surrounding areas and without producing large magnetic resonance noise and artifacts.

  20. Design of a full-dynamic-range balanced detection heterodyne gyroscope with common-path configuration.

    Science.gov (United States)

    Lin, Chu-En; Yu, Chih-Jen; Chen, Chii-Chang

    2013-04-22

    In this article, we propose an optical heterodyne common-path gyroscope which has common-path configuration and full-dynamic range. Different from traditional non-common-path optical heterodyne technique such as Mach-Zehnder or Michelson interferometers, we use a two-frequency laser light source (TFLS) which can generate two orthogonally polarized light with a beat frequency has a common-path configuration. By use of phase measurement, this optical heterodyne gyroscope not only has the capability to overcome the drawback of the traditional interferometric fiber optic gyro: lack for full-dynamic range, but also eliminate the total polarization rotation caused by SMFs. Moreover, we also demonstrate the potential of miniaturizing this gyroscope as a chip device. Theoretically, if we assume that the wavelength of the laser light is 1550nm, the SMFs are 250m in length, and the radius of the fiber ring is 3.5cm, the bias stability is 0.872 deg/hr.