Sample records for aperture masking interferometry

  1. Studying the inner regions of young stars and their disks with aperture masking interferometry (United States)

    Greenbaum, Alexandra; Sivaramakrishnan, Anand; GPI Instrument Team; NIRISS Instrument Team


    High resolution aperture masking interferometry complements coronagraphic imagers to provide a unique perspective on star and planet formation at more moderate contrast. By targeting young stars, especially those with disks, we aim to understand complex protoplanetary environments. Ground-based non-redundant masking (NRM) paired with spectrographs and polarimeters probes both thermally emitting young companions, possibly embedded in the disk or gap and scattered light in protoplanetary disks. And soon the community will have access to the most stable NRM conditions yet, with the Near Infrared Imager and Slitless Spectrograph (NIRISS) Aperture Masking Interferometry (AMI) mode on the James Webb Space Telescope. I will present my thesis work commissioning the Gemini Planet Imager’s NRM, highlighting results through both its spectroscopy and polarimetry modes, which set the stage for future space-based imaging. I will also give an overview of NIRISS-AMI capabilities and performance predictions for imaging young low-mass companions and disks, and how it will complement other instruments on JWST.

  2. AGN and quasar science with aperture masking interferometry on the James Webb Space Telescope

    CERN Document Server

    Ford, K E Saavik; Sivaramakrishnan, Anand; Martel, André R; Koekemoer, Anton; Lafrenière, David; Parmentier, Sébastien


    Due to feedback from accretion onto supermassive black holes (SMBHs), Active Galactic Nuclei (AGNs) are believed to play a key role in LambdaCDM cosmology and galaxy formation. However, AGNs' extreme luminosities and the small angular size of their accretion flows create a challenging imaging problem. We show James Webb Space Telescope's Near Infrared Imager and Slitless Spectrograph (JWST-NIRISS) Aperture Masking Interferometry (AMI) mode will enable true imaging (i.e. without any requirement of prior assumptions on source geometry) at ~65 mas angular resolution at the centers of AGNs. This is advantageous for studying complex extended accretion flows around SMBHs, and in other areas of angular-resolution-limited astrophysics. By simulating data sequences incorporating expected sources of noise, we demonstrate that JWST-NIRISS AMI mode can map extended structure at a pixel-to-pixel contrast of ~10^{-2} around an L=7.5 point source, using short exposure times (minutes). Such images will test models of AGN fee...

  3. Non-redundant Aperture Masking Interferometry (AMI) and segment phasing with JWST-NIRISS (United States)

    Sivaramakrishnan, Anand; Lafrenière, David; Ford, K. E. Saavik; McKernan, Barry; Cheetham, Anthony; Greenbaum, Alexandra Z.; Tuthill, Peter G.; Lloyd, James P.; Ireland, Michael J.; Doyon, René; Beaulieu, Mathilde; Martel, André; Koekemoer, Anton; Martinache, Frantz; Teuben, Peter


    The Aperture Masked Interferometry (AMI) mode on JWST-NIRISS is implemented as a 7-hole, 15% throughput, non-redundant mask (NRM) that operates with 5-8% bandwidth filters at 3.8, 4.3, and 4.8 microns. We present refined estimates of AMI's expected point-source contrast, using realizations of noise matched to JWST pointing requirements, NIRISS detector noise, and Rev-V JWST wavefront error models for the telescope and instrument. We describe our point-source binary data reduction algorithm, which we use as a standardized method to compare different observational strategies. For a 7.5 magnitude star we report a 10-a detection at between 8.7 and 9.2 magnitudes of contrast between 100 mas to 400 mas respectively, using closure phases and squared visibilities in the absence of bad pixels, but with various other noise sources. With 3% of the pixels unusable, the expected contrast drops by about 0.5 magnitudes. AMI should be able to reach targets as bright as M=5. There will be significant overlap between Gemini-GPI and ESO-SPHERE targets and AMI's search space, and a complementarity with NIRCam's coronagraph. We also illustrate synthesis imaging with AMI, demonstrating an imaging dynamic range of 25 at 100 mas scales. We tailor existing radio interferometric methods to retrieve a faint bar across a bright nucleus, and explain the similarities to synthesis imaging at radio wavelengths. Modest contrast observations of dusty accretion flows around AGNs will be feasible for NIRISS AMI. We show our early results of image-plane deconvolution as well. Finally, we report progress on an NRM-inspired approach to mitigate mission-level risk associated with JWST's specialized wavefront sensing hardware. By combining narrow band and medium band Nyquist-sampled images taken with a science camera we can sense JWST primary mirror segment tip-tilt to lOmas, and piston to a few nm. We can sense inter-segment piston errors of up to 5 coherence lengths of the broadest bandpass filter used

  4. Synthetic Aperture Radar Interferometry (United States)

    Rosen, P. A.; Hensley, S.; Joughin, I. R.; Li, F.; Madsen, S. N.; Rodriguez, E.; Goldstein, R. M.


    Synthetic aperture radar interferometry is an imaging technique for measuring the topography of a surface, its changes over time, and other changes in the detailed characteristics of the surface. This paper reviews the techniques of interferometry, systems and limitations, and applications in a rapidly growing area of science and engineering.

  5. Sparse aperture masking interferometry survey of transitional discs. Search for substellar-mass companions and asymmetries in their parent discs (United States)

    Willson, M.; Kraus, S.; Kluska, J.; Monnier, J. D.; Ireland, M.; Aarnio, A.; Sitko, M. L.; Calvet, N.; Espaillat, C.; Wilner, D. J.


    Context. Transitional discs are a class of circumstellar discs around young stars with extensive clearing of dusty material within their inner regions on 10s of au scales. One of the primary candidates for this kind of clearing is the formation of planet(s) within the disc that then accrete or clear their immediate area as they migrate through the disc. Aims: The goal of this survey was to search for asymmetries in the brightness distribution around a selection of transitional disc targets. We then aimed to determine whether these asymmetries trace dynamically-induced structures in the disc or the gap-opening planets themselves. Methods: Our sample included eight transitional discs. Using the Keck/NIRC2 instrument we utilised the Sparse Aperture Masking (SAM) interferometry technique to search for asymmetries indicative of ongoing planet formation. We searched for close-in companions using both model fitting and interferometric image reconstruction techniques. Using simulated data, we derived diagnostics that helped us to distinguish between point sources and extended asymmetric disc emission. In addition, we investigated the degeneracy between the contrast and separation that appear for marginally resolved companions. Results: We found FP Tau to contain a previously unseen disc wall, and DM Tau, LkHα330, and TW Hya to contain an asymmetric signal indicative of point source-like emission. We placed upper limits on the contrast of a companion in RXJ 1842.9-3532 and V2246 Oph. We ruled the asymmetry signal in RXJ 1615.3-3255 and V2062 Oph to be false positives. In the cases where our data indicated a potential companion we computed estimates for the value of McṀc and found values in the range of . Conclusions: We found significant asymmetries in four targets. Of these, three were consistent with companions. We resolved a previously unseen gap in the disc of FP Tau extending inwards from approximately 10 au. Based on observations made with the Keck observatory

  6. Progress to First Light for AMASING, an Aperture Masking Instrument (United States)

    Schmidt, Luke M.; Santoro, F. G.; Jurgenson, C. A.


    We report on construction progress for the AMASING (Aperture Masking And Speckle ImagiNG) instrument. AMASING is designed for aperture masking and speckle interferometry at optical wavelengths. This report will focus on three main aspects of the instrument construction. The optical and electronic components have been selected and are assembled in a laboratory. We describe the optical alignment procedures and expected visibility performance across the design wavelengths as well as a discussion on the types of aperture masks developed for the instrument. The support structure and enclosure have been designed to provide a stable platform for the instrument optics. We document the construction, predicted performance and the procedure for aligning the structure with the optical axis of the telescope. Finally we discuss the instrument software control architecture and interface with the telescope. This work has been supported by LANL-NMT MOU UCDRD funding, a College Cost Reduction and Access Act grant to Amarillo College, the New Mexico Space Grant Consortium and the New Mexico Tech Graduate Student Association Matuszeski Research Grant.

  7. Mask Design for the Space Interferometry Mission Internal Metrology (United States)

    Marx, David; Zhao, Feng; Korechoff, Robert


    This slide presentation reviews the mask design used for the internal metrology of the Space Interferometry Mission (SIM). Included is information about the project, the method of measurements with SIM, the internal metrology, numerical model of internal metrology, wavefront examples, performance metrics, and mask design

  8. Coronagraph-Integrated Wavefront Sensing with a Sparse Aperture Mask

    CERN Document Server

    Subedi, Hari; Kasdin, N Jeremy; Cavanagh, Kathleen; Riggs, A J Eldorado


    Stellar coronagraph performance is highly sensitive to optical aberrations. In order to effectively suppress starlight for exoplanet imaging applications, low-order wavefront aberrations entering a coronagraph such as tip-tilt, defocus and coma must be determined and compensated. Previous authors have established the utility of pupil-plane masks (both non-redundant/sparse-aperture and generally asymmetric aperture masks) for wavefront sensing. Here we show how a sparse aperture mask (SAM) can be integrated with a coronagraph to measure low-order, differential phase aberrations. Starlight rejected by the coronagraph's focal plane stop is collimated to a relay pupil, where the mask forms an interference fringe pattern on a subsequent detector. Our numerical Fourier propagation models show that the information encoded in the fringe intensity distortions is sufficient to accurately discriminate and estimate Zernike phase modes extending from tip-tilt up to radial degree $n=5$, with amplitude up to $\\lambda/20$ RM...

  9. Terahertz coded aperture mask using vanadium dioxide bowtie antenna array (United States)

    Nadri, Souheil; Percy, Rebecca; Kittiwatanakul, Lin; Arsenovic, Alex; Lu, Jiwei; Wolf, Stu; Weikle, Robert M.


    Terahertz imaging systems have received substantial attention from the scientific community for their use in astronomy, spectroscopy, plasma diagnostics and security. One approach to designing such systems is to use focal plane arrays. Although the principle of these systems is straightforward, realizing practical architectures has proven deceptively difficult. A different approach to imaging consists of spatially encoding the incoming flux of electromagnetic energy prior to detection using a reconfigurable mask. This technique is referred to as "coded aperture" or "Hadamard" imaging. This paper details the design, fabrication and testing of a prototype coded aperture mask operating at WR-1.5 (500-750 GHz) that uses the switching properties of vanadium dioxide(VO2). The reconfigurable mask consists of bowtie antennas with vanadium dioxide VO2 elements at the feed points. From the symmetry, a unit cell of the array can be represented by an equivalent waveguide whose dimensions limit the maximum operating frequency. In this design, the cutoff frequency of the unit cell is 640 GHz. The VO2 devices are grown using reactive-biased target ion beam deposition. A reflection coefficient (S11) measurement of the mask in the WR-1.5 (500-750 GHz) band is conducted. The results are compared with circuit models and found to be in good agreement. A simulation of the transmission response of the mask is conducted and shows a transmission modulation of up to 28 dB. This project is a first step towards the development of a full coded aperture imaging system operating at WR-1.5 with VO2 as the mask switching element.

  10. Three-dimensional imaging using differential synthetic aperture interferometry (United States)

    Zhang, Ning; Zhou, Yu; Sun, Jianfeng; Zhi, Ya'nan; Lu, Zhiyong; Xu, Qian; Sun, Zhiwei; Liu, Liren


    Synthetic aperture radar interferometry (InSAR) can gain three-dimensional topography with high spatial resolution and height accuracy using across track interferometry[1]. Conventional InSAR produce three-dimensional images from SAR data. But when the working wavelength transit from microwave to optical wave, the transmission antenna and receive antenna become very sensitive to platform vibration and beam quality[2]. Through differential receive antenna formation, we can relax the requirement of platform and laser using synthetic aperture imaging ladar (SAIL) concept[3]. Line-of-sight motion constraints are reduced by several orders of magnitude. We introduce two distinctive forms of antenna formation according to the position of interferogram. The first architecture can simplify the interferogram processing and phase extraction algorithm under time-division multiplex operation. The second architecture can process the 2D coordinate and height coordinate at the same time. Using optical diffraction theory, a systematic theory of side-looking SAIL is mathematically formulated and the necessary conditions for assuring a correct phase history are established[4]. Based on optical transformation and regulation of wavefront, a side-looking SAIL of two distinctive architectures is invented and the basic principle, systematic theory, design equations and necessary conditions are presented. It is shown that high height accuracy can be reached and the influences from atmospheric turbulence and unmodeled line-of-sight motion can be automatically compensated.

  11. Synthetic aperture radar and interferometry development at Sandia National Laboratories

    Energy Technology Data Exchange (ETDEWEB)



    Environmental monitoring, earth-resource mapping, and military systems require broad-area imaging at high resolutions. Many times the imagery must be acquired in inclement weather or during night as well as day. Synthetic aperture radar (SAR) provides such a capability. SAR systems take advantage of the long-range propagation characteristics of radar signals and the complex information processing capability of modern digital electronics to provide high resolution imagery. SAR complements photographic and other optical imaging capabilities because of the minimum constrains on time-of-day and atmospheric conditions and because of the unique responses of terrain and cultural targets to radar frequencies. Interferometry is a method for generating a three-dimensional image of terrain. The height projection is obtained by acquiring two SAR images from two slightly differing locations. It is different from the common method of stereoscopic imaging for topography. The latter relies on differing geometric projections for triangulation to define the surface geometry whereas interferometry relies on differences in radar propagation times between the two SAR locations. This paper presents the capabilities of SAR, explains how SAR works, describes a few SAR applications, provides an overview of SAR development at Sandia, and briefly describes the motion compensation subsystem.

  12. An image-plane algorithm for JWST's non-redundant aperture mask data

    CERN Document Server

    Greenbaum, Alexandra Z; Sivaramakrishnan, Anand; Lacour, Sylvestre


    The high angular resolution technique of non-redundant masking (NRM) or aperture masking interferometry (AMI) has yielded images of faint protoplanetary companions of nearby stars from the ground. AMI on James Webb Space Telescope (JWST)'s Near Infrared Imager and Slitless Spectrograph (NIRISS) has a lower thermal background than ground-based facilites and does not suffer from atmospheric instability. NIRISS AMI images are likely to have 90 - 95% Strehl ratio between 2.77 and 4.8 micron. In this paper we quantify factors that limit the raw point source contrast of JWST NRM. We develop an analytic model of the NRM point spread function which includes different optical path delays (pistons) between mask holes and fit the model parameters with image plane data. It enables a straightforward way to exclude bad pixels, is suited to limited fields of view, and can incorporate effects such as intra-pixel sensitivity variations. We simulate various sources of noise to estimate their effect on the standard deviation of...

  13. Extra Wideband Polarimetry, Interferometry and Polarimetric Interferometry in Synthetic Aperture Remote Sensing(Special Issue on Advances in Radar Systems)


    Boerner, Wolfgang-Martin; Yamaguchi, Yoshio


    The development of Radar Polarimetry and Radar Interferometry is advancing rapidly. Whereas with radar polarimetry, the textural fine-structure, target orientation, symmetries and material constituents can be recovered with considerable improvement above that of standard amplitude-only radar; with radar interferometry the spatial(in depth)structure can be explored. In Polarimetric Interferometric Synthetic Aperture Radar(POL-IN-SAR)Imaging, it is possible to recover such co-registered textura...


    Energy Technology Data Exchange (ETDEWEB)

    Greenbaum, Alexandra Z. [Johns Hopkins University Department of Physics and Astronomy 3400 North Charles, Baltimore, MD 21218 (United States); Pueyo, Laurent; Sivaramakrishnan, Anand [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Lacour, Sylvestre [LESIA, CNRS/UMR-8109, Observatoire de Paris, UPMC, Université Paris Diderot 5 place Jules Janssen, 92195 Meudon (France)


    The high angular resolution technique of non-redundant masking (NRM) or aperture masking interferometry (AMI) has yielded images of faint protoplanetary companions of nearby stars from the ground. AMI on James Webb Space Telescope (JWST)'s Near Infrared Imager and Slitless Spectrograph (NIRISS) has a lower thermal background than ground-based facilities and does not suffer from atmospheric instability. NIRISS AMI images are likely to have 90%-95% Strehl ratio between 2.77 and 4.8 μm. In this paper we quantify factors that limit the raw point source contrast of JWST NRM. We develop an analytic model of the NRM point spread function which includes different optical path delays (pistons) between mask holes and fit the model parameters with image plane data. It enables a straightforward way to exclude bad pixels, is suited to limited fields of view, and can incorporate effects such as intra-pixel sensitivity variations. We simulate various sources of noise to estimate their effect on the standard deviation of closure phase, σ{sub CP} (a proxy for binary point source contrast). If σ{sub CP} < 10{sup –4} radians—a contrast ratio of 10 mag—young accreting gas giant planets (e.g., in the nearby Taurus star-forming region) could be imaged with JWST NIRISS. We show the feasibility of using NIRISS' NRM with the sub-Nyquist sampled F277W, which would enable some exoplanet chemistry characterization. In the presence of small piston errors, the dominant sources of closure phase error (depending on pixel sampling, and filter bandwidth) are flat field errors and unmodeled variations in intra-pixel sensitivity. The in-flight stability of NIRISS will determine how well these errors can be calibrated by observing a point source. Our results help develop efficient observing strategies for space-based NRM.

  15. The Keck Aperture Masking Experiment: Dust Enshrouded Red Giants

    CERN Document Server

    Blasius, T D; Tuthill, P G; Danchi, W C; Anderson, M


    While the importance of dusty asymptotic giant branch (AGB) stars to galactic chemical enrichment is widely recognised, a sophisticated understanding of the dust formation and wind-driving mechanisms has proven elusive due in part to the difficulty in spatially-resolving the dust formation regions themselves. We have observed twenty dust-enshrouded AGB stars as part of the Keck Aperture Masking Experiment, resolving all of them in multiple near-infrared bands between 1.5 microns and 3.1 microns. We find 45% of the targets to show measurable elongations that, when correcting for the greater distances of the targets, would correspond to significantly asymmetric dust shells on par with the well-known cases of IRC+10216 or CIT6. Using radiative transfer models, we find the sublimation temperature of 1130 +- 90 K and 1170 +- 60 K for silicates and amorphous carbon respectively, both somewhat lower than expected from laboratory measurements and vastly below temperatures inferred from the inner edge of YSO disks. Th...

  16. An aperture masking mode for the MICADO instrument

    CERN Document Server

    Lacour, S; Gendron, E; Boccaletti, A; Galicher, R; Clénet, Y; Gratadour, D; Buey, T; Rousset, G; Hartl, M; Davies, R


    MICADO is a near-IR camera for the Europea ELT, featuring an extended field (75" diameter) for imaging, and also spectrographic and high contrast imaging capabilities. It has been chosen by ESO as one of the two first-light instruments. Although it is ultimately aimed at being fed by the MCAO module called MAORY, MICADO will come with an internal SCAO system that will be complementary to it and will deliver a high performance on axis correction, suitable for coronagraphic and pupil masking applications. The basis of the pupil masking approach is to ensure the stability of the optical transfer function, even in the case of residual errors after AO correction (due to non common path errors and quasi-static aberrations). Preliminary designs of pupil masks are presented. Trade-offs and technical choices, especially regarding redundancy and pupil tracking, are explained.

  17. Terahertz inverse synthetic aperture radar imaging using self-mixing interferometry with a quantum cascade laser. (United States)

    Lui, H S; Taimre, T; Bertling, K; Lim, Y L; Dean, P; Khanna, S P; Lachab, M; Valavanis, A; Indjin, D; Linfield, E H; Davies, A G; Rakić, A D


    We propose a terahertz (THz)-frequency synthetic aperture radar imaging technique based on self-mixing (SM) interferometry, using a quantum cascade laser. A signal processing method is employed which extracts and exploits the radar-related information contained in the SM signals, enabling the creation of THz images with improved spatial resolution. We demonstrate this by imaging a standard resolution test target, achieving resolution beyond the diffraction limit.

  18. Mapping Ocean Surface Topography with a Synthetic-Aperture Interferometry Radar (United States)

    Fu, Lee-Lueng; Rodriguez, Ernesto


    We propose to apply the technique of synthetic aperture radar interferometry to the measurement of ocean surface topography at spatial resolution approaching 1 km. The measurement will have wide ranging applications in oceanography, hydrology. and marine geophysics. The oceanographic and related societal applications are briefly discussed in the paper. To meet the requirements for oceanographic applications, the instrument must be flown in an orbit with proper sampling of ocean tides.

  19. Laboratory coded aperture imaging experiments: radial hole coded masks and depth-sensitive CZT detectors

    CERN Document Server

    Hong, J; Zhang, M; Bellm, E C; Yousef, A; Noss, J; Grindlay, J E; Narita, T


    The proposed black-hole finder mission EXIST will consist of multiple wide-field hard X-ray coded-aperture telescopes. The high science goals set for the mission require innovations in telescope design. In particular, wide energy band coverage and fine angular resolution require relatively thick coded masks and thick detectors compared to their pixel size, which may introduce mask self-collimation and depth-induced image blurring with conventional design approaches. Previously we proposed relatively simple solutions to these potential problems: radial hole for mask selfcollimation and cathode depth sensing detector for image blurring. We have now performed laboratory experiments to explore the potential of these two techniques. The experimental results show that the radial hole mask greatly alleviates mask self-collimation and a ~1 mm resolution depth-sensitive detector scheme can be relatively easily achieved for the large scale required for EXIST.

  20. Terahertz Coded Aperture Mask using a Vanadium Dioxide Bowtie Antenna Array

    CERN Document Server

    Nadri, Souheil; Kittiwatanakul, Lin; Arsenovic, Alex; Lu, Jiwei; Wolf, Stu; Weikle, Robert M


    Terahertz imaging systems have received substantial attention from the scientific community for their use in astronomy, spectroscopy, plasma diagnostics and security. One approach to designing such systems is to use focal plane arrays. Although the principle of these systems is straightforward, realizing practical architectures has proven deceptively difficult. A different approach to imaging consists of spatially encoding the incoming flux of electromagnetic energy prior to detection using a reconfigurable mask. This technique is referred to as coded aperture or Hadamard imaging. This paper details the design, fabrication and testing of a prototype coded aperture mask operating at WR 1.5 (500 to 750 GHz) that uses the switching properties of vanadium dioxide (VO2). The reconfigurable mask consists of bowtie antennas with vanadium dioxide VO2 elements at the feed points. From the symmetry, a unit cell of the array can be represented by an equivalent waveguide whose dimensions limit the maximum operating frequ...

  1. Towards Laser-Guide-Stars for Multi-Aperture Interferometry: an application to the Hypertelescope

    CERN Document Server

    Nuñez, Paul D; Riaud, Pierre


    Optical interferometry has been successful at achieving milliarcsecond resolution on bright stars. Imaging performance can improve greatly by increasing the number of baselines, which has motivated proposals to build large (~ 100 m) optical interferometers with tens to hundreds of telescopes. It is also desirable to adaptively correct atmospheric turbulence to obtain direct phased images of astrophysical sources. When a natural guide star is not available, we investigate the feasibility of using a modified laser-guide-star technique that is suitable for large diluted apertures. The method consists of using sub-sets of apertures to create an array of artificial stars in the sodium layer and collecting back-scattered light with the same sub-apertures. We present some numerical and laboratory simulations that quantify the requirements and sensitivity of the technique.

  2. Hybrid coded aperture and Compton imaging using an active mask

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, L.J. [Los Alamos National Laboratory, Los Alamos, NM (United States)], E-mail:; Wallace, M.S.; Galassi, M.C.; Hoover, A.S.; Mocko, M.; Palmer, D.M.; Tornga, S.R.; Kippen, R.M. [Los Alamos National Laboratory, Los Alamos, NM (United States); Hynes, M.V.; Toolin, M.J.; Harris, B.; McElroy, J.E. [Raytheon Integrated Defense Systems, Tewksbury, MA (United States); Wakeford, D. [Bubble Technology Industries, Chalk River, Ontario (Canada); Lanza, R.C.; Horn, B.K.P. [Massachusetts Institute of Technology, Cambridge, MA (United States); Wehe, D.K. [University of Michigan, Ann Arbor, MI (United States)


    The trimodal imager (TMI) images gamma-ray sources from a mobile platform using both coded aperture (CA) and Compton imaging (CI) modalities. In this paper we will discuss development and performance of image reconstruction algorithms for the TMI. In order to develop algorithms in parallel with detector hardware we are using a GEANT4 [J. Allison, K. Amako, J. Apostolakis, H. Araujo, P.A. Dubois, M. Asai, G. Barrand, R. Capra, S. Chauvie, R. Chytracek, G. Cirrone, G. Cooperman, G. Cosmo, G. Cuttone, G. Daquino, et al., IEEE Trans. Nucl. Sci. NS-53 (1) (2006) 270] based simulation package to produce realistic data sets for code development. The simulation code incorporates detailed detector modeling, contributions from natural background radiation, and validation of simulation results against measured data. Maximum likelihood algorithms for both imaging methods are discussed, as well as a hybrid imaging algorithm wherein CA and CI information is fused to generate a higher fidelity reconstruction.

  3. Optimized focal and pupil plane masks for vortex coronagraphs on telescopes with obstructed apertures (United States)

    Ruane, Garreth J.; Absil, Olivier; Huby, Elsa; Mawet, Dimitri; Delacroix, Christian; Carlomagno, Brunella; Piron, Pierre; Swartzlander, Grover A.


    We present methods for optimizing pupil and focal plane optical elements that improve the performance of vortex coronagraphs on telescopes with obstructed or segmented apertures. Phase-only and complex masks are designed for the entrance pupil, focal plane, and the plane of the Lyot stop. Optimal masks are obtained using both analytical and numerical methods. The latter makes use of an iterative error reduction algorithm to calculate "correcting" optics that mitigate unwanted diffraction from aperture obstructions. We analyze the achieved performance in terms of starlight suppression, contrast, off-axis image quality, and chromatic dependence. Manufacturing considerations and sensitivity to aberrations are also discussed. This work provides a path to joint optimization of multiple coronagraph planes to maximize sensitivity to exoplanets and other faint companions.

  4. Optimized focal and pupil plane masks for vortex coronagraphs on telescopes with obstructed apertures

    CERN Document Server

    Ruane, Garreth J; Huby, Elsa; Mawet, Dimitri; Delacroix, Christian; Carlomagno, Brunella; Piron, Pierre; Swartzlander, Grover A


    We present methods for optimizing pupil and focal plane optical elements that improve the performance of vortex coronagraphs on telescopes with obstructed or segmented apertures. Phase-only and complex masks are designed for the entrance pupil, focal plane, and the plane of the Lyot stop. Optimal masks are obtained using both analytical and numerical methods. The latter makes use of an iterative error reduction algorithm to calculate "correcting" optics that mitigate unwanted diffraction from aperture obstructions. We analyze the achieved performance in terms of starlight suppression, contrast, off-axis image quality, and chromatic dependence. Manufacturing considerations and sensitivity to aberrations are also discussed. This work provides a path to joint optimization of multiple coronagraph planes to maximize sensitivity to exoplanets and other faint companions.

  5. FIRST, a fibered aperture masking instrument. I. First on-sky test results (United States)

    Huby, E.; Perrin, G.; Marchis, F.; Lacour, S.; Kotani, T.; Duchêne, G.; Choquet, E.; Gates, E. L.; Woillez, J. M.; Lai, O.; Fédou, P.; Collin, C.; Chapron, F.; Arslanyan, V.; Burns, K. J.


    Aims: In this paper we present the first on-sky results with the fibered aperture masking instrument FIRST. Its principle relies on the combination of spatial filtering and aperture masking using single-mode fibers, a novel technique that is aimed at high dynamic range imaging with high angular resolution. Methods: The prototype has been tested with the Shane 3-m telescope at Lick Observatory. The entrance pupil is divided into sub-pupils feeding single-mode fibers. The flux injection into the fibers is optimized by a segmented mirror. The beams are spectrally dispersed and recombined in a non-redundant exit configuration in order to retrieve all contrasts and phases independently. Results: The instrument works at visible wavelengths between 600 nm and 760 nm and currently uses nine of the 30 43 cm sub-apertures constituting the full pupil. First fringes were obtained on Vega and Deneb. Stable closure phases were measured with standard deviations on the order of 1 degree. Closure phase precision can be further improved by addressing some of the remaining sources of systematic errors. While the number of fibers used in the experiment was too small to reliably estimate visibility amplitudes, we have measured closure amplitudes with a precision of 10% in the best case. Conclusions: These first promising results obtained under real observing conditions validate the concept of the fibered aperture masking instrument and open the way for a new type of ground-based instrument working in the visible. The next steps of the development will be to improve the stability and the sensitivity of the instrument in order to achieve more accurate closure phase and visibility measurements, and to increase the number of sub-pupils to reach full pupil coverage.

  6. Annular sub-aperture stitching interferometry testing for large-caliber aspheric (United States)

    Wu, Pengfei; Yang, Shuming; Sun, Lin; Zhao, Pu; Jiang, Zhuangde


    An annular sub-aperture stitching interferometry testing is proposed for large-caliber aspheric lens testing, expanding the dynamic range of the interferometer, broadening the scope of the measurement, and reducing the cost of the measurement to a large extent without the use of compensating elements. The large-caliber aspheric is divided into several annular sub-apertures, and there are some overlapping areas between each two adjacent sub-apertures. When testing, the test aspheric is moved along the optical axis according to path planning so that the reference spherical shape and the test aspheric interest at points of common tangency to reduce the fringe density of the sub-aperture. However, in the process of moving the test optic, six DOF (degrees of freedom) misalignment errors will occur. According to the rigid body kinematics theory, the misalignment error separation model is established so that the misalignment factors can be calculated by the information of each overlapping regions. Then all sub-apertures are unified to the same reference with proper algorithm, and subsequently, misalignment error of the reference is removed by Zernike polynomial fitting, and the whole surface error is recovered. Simulation results are shown to demonstrate the feasibility of the method we developed. By analyzing the influence of the six DOF on the stitching result, the most important factor is obtained, and some measures are taken, that is, a measurement system combining two interferometers is designed, one of which is to measure the departures between the reference and the aspheric, and another to test the piston errors to be transmitted to the control system to improve the accuracy.

  7. Synthetic Aperture Radar Interferometry for Digital Elevation Model of Kuwait Desert - Analysis of Errors (United States)

    Jassar, H. K. Al; Rao, K. S.


    Using different combinations of 29 Advanced Synthetic Aperture Radar (ASAR) images, 43 Digital Elevations Models (DEM) were generated adopting SAR Interferometry (InSAR) technique. Due to sand movement in desert terrain, there is a poor phase correlation between different SAR images. Therefore, suitable methodology for generating DEMs of Kuwait desert terrain using InSAR technique were worked out. Time series analysis was adopted to derive the best DEM out of 43 DEMs. The problems related to phase de-correlation over desert terrain are discussed. Various errors associated with the DEM generation are discussed which include atmospheric effects, penetration into soil medium, sand movement. The DEM of Shuttle Radar Topography Mission (SRTM) is used as a reference. The noise levels of DEM of SRTM are presented.

  8. Three-dimensional coastal geomorphology deformation modelling using differential synthetic aperture interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Marghany, Maged [Universiti Teknologi Malaysia, Skudai, Johor Bahru (Malaysia). Inst. for Science and Technology Geospatial (INSTeG)


    This work presents a new approach for three-dimensional (3D) coastal deformation simulation using differential synthetic aperture interferometry (DInSAR). In doing so, conventional InSAR procedures are implemented to three repeat passes of RADARSAT-1 SAR fine mode data (F1). Further, the DInSAR method is implemented with the phase unwrapping technique. Consequently, DInSAR is used to eliminate the phase decorrelation impact from the interferograms. The study shows the accurate performance of DInSAR with a root mean square error of 0.02 {+-} 0.21 m and 90% confidence intervals. In conclusion, the DInSAR technique produces an accurate 3D coastal geomorphology reconstruction. (orig.)

  9. FIRST, a fibered aperture masking instrument. I. First on-sky test results

    CERN Document Server

    Huby, E; Marchis, F; Lacour, S; Kotani, T; Duchêne, G; Choquet, E; Gates, E L; Woillez, J M; Lai, O; Fédou, P; Collin, C; Chapron, F; Arslanyan, V; Burns, K J


    In this paper we present the first on-sky results with the fibered aperture masking instrument FIRST. Its principle relies on the combination of spatial filtering and aperture masking using single-mode fibers, a novel technique that is aimed at high dynamic range imaging with high angular resolution. The prototype has been tested with the Shane 3-m telescope at Lick Observatory. The entrance pupil is divided into subpupils feeding single-mode fibers. The flux injection into the fibers is optimized by a segmented mirror. The beams are spectrally dispersed and recombined in a non-redundant exit configuration in order to retrieve all contrasts and phases independently. The instrument works at visible wavelengths between 600 nm and 760 nm and currently uses nine of the 30 43 cm subapertures constituting the full pupil. First fringes were obtained on Vega and Deneb. Stable closure phases were measured with standard deviations on the order of 1 degree. Closure phase precision can be further improved by addressing s...

  10. First Experimental Results Using Sparse Aperture Mask for Low Order Wavefront Sensing (United States)

    Subedi, Hari; Zimmerman, Neil T.; Kasdin, N. Jeremy; Eldorado Riggs, A. J.


    We can determine the existence of life outside of earth by analyzing the spectra of exoplanets. Such direct imaging will provide the capability to thoroughly characterize an exoplanet's atmosphere. Direct imaging of exoplanets, however, has many technical challenges and difficulties: scattering and diffraction of light and the large difference in contrast, which is the ratio of brightness between the bright star and the dimmer planet. A coronagraph is an optical device that manipulates the diffraction of starlight and creates a region of high contrast (dark hole) where the dimmer planets can be seen. While in principle the level of contrast required for direct imaging of exoplanets can be achieved by stellar coronagraphic imaging, the resulting dark hole is highly sensitive to phase aberrations. In order to effectively suppress starlight for exoplanet imaging applications, low-order wavefront aberrations entering a coronagraph such as tip-tilt, defocus and coma must be determined and compensated for. A sparse-aperture mask (SAM) can be integrated in the telescopic imaging system to make precise estimate of low-order wavefront aberrations. In this technique, the starlight rejected by the coronagraph's focal plane stop is collimated to a relay pupil, where the mask forms an interference fringe pattern on a detector and the phase aberrations are inferred from this fringe pattern. At Princeton's High Contrast Imaging Lab (HCIL), we have numerically proved this concept and we are currently working on verifying it experimentally.

  11. Experimental Verification of Sparse Aperture Mask for Low Order Wavefront Sensing (United States)

    Subedi, Hari; Kasdin, N. Jeremy


    To directly image exoplanets, future space-based missions are equipped with coronagraphs which manipulate the diffraction of starlight and create regions of high contrast called dark holes. Theoretically, coronagraphs can be designed to achieve the high level of contrast required to image exoplanets, which are billions of times dimmer than their host stars, however the aberrations caused by optical imperfections and thermal fluctuations cause the degradation of contrast in the dark holes. Focal plane wavefront control (FPWC) algorithms using deformable mirrors (DMs) are used to mitigate the quasi-static aberrations caused by optical imperfections. Although the FPWC methods correct the quasi-static aberrations, they are blind to dynamic errors caused by telescope jitter and thermal fluctuations. At Princeton's High Contrast Imaging Lab we have developed a new technique that integrates a sparse aperture mask with the coronagraph to estimate these low-order dynamic wavefront errors. This poster shows the effectiveness of a SAM Low-Order Wavefront Sensor in estimating and correcting these errors via simulation and experiment and compares the results to other methods, such as the Zernike Wavefront Sensor planned for WFIRST.

  12. Apertures

    CERN Document Server

    Hansen, R C


    Microwave Scanning Antennas, Volume I: Apertures is a comprehensive account of phased arrays, multiple beam arrays, time domain and synthetic apertures, and adaptive antennas. Advances in continuous apertures and near field theory are discussed. Low noise and monopulse apertures, optical scanners, and large radomes are also covered, along with radio astronomy instruments and associated theory.Comprised of five chapters, this volume begins with an overview of aperture theory as well as aperture distributions and near field theory. The second and third chapters deal with mechanically steered and

  13. Machine learning and synthetic aperture refocusing approach for more accurate masking of fish bodies in 3D PIV data (United States)

    Ford, Logan; Bajpayee, Abhishek; Techet, Alexandra


    3D particle image velocimetry (PIV) is becoming a popular technique to study biological flows. PIV images that contain fish or other animals around which flow is being studied, need to be appropriately masked in order to remove the animal body from the 3D reconstructed volumes prior to calculating particle displacement vectors. Presented here is a machine learning and synthetic aperture (SA) refocusing based approach for more accurate masking of fish from reconstructed intensity fields for 3D PIV purposes. Using prior knowledge about the 3D shape and appearance of the fish along with SA refocused images at arbitrarily oriented focal planes, the location and orientation of a fish in a reconstructed volume can be accurately determined. Once the location and orientation of a fish in a volume is determined, it can be masked out.

  14. A novel mask-based approach to improve low-k1 corner and angle definition in alternating-aperture phase-shift mask structures (United States)

    Nakagawa, Kent H.; Siefers, David; MacDonald, Susan; Buck, Peter D.


    A novel approach to improve the imaging of the critical magnetic pole structure in the disk drive read head is introduced. A 90-degree sub-resolution opening is added to an alternating aperture phase shift mask to reduce a strong proximity effect in the non-Manhattan tapered section, while maintaining the enhanced printability of the linear segment of the pole region.. Simulation indicates that this opening provides a method to correct the observed distortion in the printed edge without reducing the effectiveness of the altPSM character of the pole itself. We have designed test patterns with this concept and built photomasks to evaluate mask manufacturability and to empirically test the impact of the 90-degree window on final pattern fidelity on wafer. Preliminary results indicate positive correction effects, as well as some potential issues which may be resolved using additional, established correction approaches.

  15. Unveiling the near-infrared structure of the massive-young stellar object NGC3603 IRS 9A with sparse aperture masking and spectroastrometry

    CERN Document Server

    Sanchez-Bermudez, J; Tuthill, P; Alberdi, A; Schödel, R; Lacour, S


    According to the current theories, massive stars gather mass during their initial phases via accreting disk-like structures. However, those disks have remained elusive for massive young objects. This is mainly because of the observational challenges due to the large distances at which they are located, their rareness, and the high interstellar extinction. Therefore, the study of each young massive stellar object matters. NGC 3603 IRS 9A is a young massive stellar object still surrounded by an envelope of molecular gas. Previous mid-infrared observations with long-baseline interferometry provided evidence for a disk of 50 mas diameter at its core. This work studies the IRS 9A physics and morphology at near-infrared wavelengths. This study analyzed new sparse aperture masking data taken with NACO/VLT at K s and Lp filters in addition to archive CRIRES spectra of the H2 and Br_gamma lines. The calibrated visibilities trends of the Ks and Lp bands suggest the presence of a partially resolved compact object of 30 ...

  16. Ground settlement of Chek Lap Kok Airport, Hong Kong,detected by satellite synthetic aperture radar interferometry

    Institute of Scientific and Technical Information of China (English)


    Satellite synthetic aperture radar (SAR) interferometry is used to investigate the slowly accumulating ground settlement at the new Chek Lap Kok Airport in Hong Kong. Most of the land occupied by the airport was reclaimed from the sea and therefore certain ground settlement in the area has been expected. A pair of ERS-2 SAR images spanning nearly a year is used in the study. The high spatial resolution (20 m× 20 m) ground settlement map derived indicates that the settlement that occurred in the area over the time period is as large as 50 mm. The SAR measurement results agree with the levelling measurements at some benchmarks in the area to well within 1 cm(rms error),and the overall correlation between the two types of results is 0.89. The paper presents some brief background of interferometric SAR, and outlines the data processing methods and results.

  17. Synthetic Aperture Radar (SAR Interferometry for Assessing Wenchuan Earthquake (2008 Deforestation in the Sichuan Giant Panda Site

    Directory of Open Access Journals (Sweden)

    Fulong Chen


    Full Text Available Synthetic aperture radar (SAR has been an unparalleled tool in cloudy and rainy regions as it allows observations throughout the year because of its all-weather, all-day operation capability. In this paper, the influence of Wenchuan Earthquake on the Sichuan Giant Panda habitats was evaluated for the first time using SAR interferometry and combining data from C-band Envisat ASAR and L-band ALOS PALSAR data. Coherence analysis based on the zero-point shifting indicated that the deforestation process was significant, particularly in habitats along the Min River approaching the epicenter after the natural disaster, and as interpreted by the vegetation deterioration from landslides, avalanches and debris flows. Experiments demonstrated that C-band Envisat ASAR data were sensitive to vegetation, resulting in an underestimation of deforestation; in contrast, L-band PALSAR data were capable of evaluating the deforestation process owing to a better penetration and the significant coherence gain on damaged forest areas. The percentage of damaged forest estimated by PALSAR decreased from 20.66% to 17.34% during 2009–2010, implying an approximate 3% recovery rate of forests in the earthquake impacted areas. This study proves that long-wavelength SAR interferometry is promising for rapid assessment of disaster-induced deforestation, particularly in regions where the optical acquisition is constrained.

  18. Mapping three-dimensional surface deformation by combining multiple-aperture interferometry and conventional interferometry: Application to the June 2007 eruption of Kilauea Volcano, Hawaii (United States)

    Jung, H.-S.; Lu, Zhiming; Won, J.-S.; Poland, Michael P.; Miklius, Asta


    Surface deformation caused by an intrusion and small eruption during June 17-19, 2007, along the East Rift Zone of Kilauea Volcano, Hawaii, was three-dimensionally reconstructed from radar interferograms acquired by the Advanced Land Observing Satellite (ALOS) phased-array type L-band synthetic aperture radar (SAR) (PALSAR) instrument. To retrieve the 3-D surface deformation, a method that combines multiple-aperture interferometry (MAI) and conventional interferometric SAR (InSAR) techniques was applied to one ascending and one descending ALOS PALSAR interferometric pair. The maximum displacements as a result of the intrusion and eruption are about 0.8, 2, and 0.7 m in the east, north, and up components, respectively. The radar-measured 3-D surface deformation agrees with GPS data from 24 sites on the volcano, and the root-mean-square errors in the east, north, and up components of the displacement are 1.6, 3.6, and 2.1 cm, respectively. Since a horizontal deformation of more than 1 m was dominantly in the north-northwest-south-southeast direction, a significant improvement of the north-south component measurement was achieved by the inclusion of MAI measurements that can reach a standard deviation of 3.6 cm. A 3-D deformation reconstruction through the combination of conventional InSAR and MAI will allow for better modeling, and hence, a more comprehensive understanding, of the source geometry associated with volcanic, seismic, and other processes that are manifested by surface deformation.

  19. A-Differential Synthetic Aperture Radar Interferometry analysis of a Deep Seated Gravitational Slope Deformation occurring at Bisaccia (Italy). (United States)

    Di Martire, Diego; Novellino, Alessandro; Ramondini, Massimo; Calcaterra, Domenico


    This paper presents the results of an investigation on a Deep Seated Gravitational Slope Deformation (DSGSD), previously only hypothesized by some authors, affecting Bisaccia, a small town located in Campania region, Italy. The study was conducted through the integration of conventional methods (geological-geomorphological field survey, air-photo interpretation) and an Advanced-Differential Interferometry Synthetic Aperture Radar (A-DInSAR) technique. The DSGSD involves a brittle lithotype (conglomerates of the Ariano Irpino Supersynthem) resting over a Structurally Complex Formation (Varycoloured Clays of Calaggio Formation). At Bisaccia, probably as a consequence of post-cyclic recompression phenomena triggered by reiterated seismic actions, the rigid plate made up of conglomeratic sediments resulted to be split in five portions, showing different rates of displacements, whose deformations are in the order of some centimeter/year, thus inducing severe damage to the urban settlement. A-DInSAR techniques confirmed to be a reliable tool in monitoring slow-moving landslides. In this case 96 ENVIronmental SATellite-Advanced Synthetic Aperture Radar (ENVISAT-ASAR) images, in ascending and descending orbits, have been processed using SUBSOFT software, developed by the Remote Sensing Laboratory (RSLab) group from the Universitat Politècnica de Catalunya (UPC). The DInSAR results, coupled with field survey, supported the analysis of the instability mechanism and confirmed the historical record of the movements already available for the town.

  20. A-Differential Synthetic Aperture Radar Interferometry analysis of a Deep Seated Gravitational Slope Deformation occurring at Bisaccia (Italy)

    Energy Technology Data Exchange (ETDEWEB)

    Di Martire, Diego, E-mail: [Department of Earth Sciences, Environment and Resources, Federico II University of Naples, Largo San Marcellino 10, 80138 Naples (Italy); Novellino, Alessandro, E-mail: [Department of Earth Sciences, Environment and Resources, Federico II University of Naples, Largo San Marcellino 10, 80138 Naples (Italy); Ramondini, Massimo, E-mail: [Department of Civil, Architectural and Environmental Engineering, Federico II University of Naples, via Claudio 21, 80125 Naples (Italy); Calcaterra, Domenico, E-mail: [Department of Earth Sciences, Environment and Resources, Federico II University of Naples, Largo San Marcellino 10, 80138 Naples (Italy)


    This paper presents the results of an investigation on a Deep Seated Gravitational Slope Deformation (DSGSD), previously only hypothesized by some authors, affecting Bisaccia, a small town located in Campania region, Italy. The study was conducted through the integration of conventional methods (geological-geomorphological field survey, air-photo interpretation) and an Advanced-Differential Interferometry Synthetic Aperture Radar (A-DInSAR) technique. The DSGSD involves a brittle lithotype (conglomerates of the Ariano Irpino Supersynthem) resting over a Structurally Complex Formation (Varycoloured Clays of Calaggio Formation). At Bisaccia, probably as a consequence of post-cyclic recompression phenomena triggered by reiterated seismic actions, the rigid plate made up of conglomeratic sediments resulted to be split in five portions, showing different rates of displacements, whose deformations are in the order of some centimeter/year, thus inducing severe damage to the urban settlement. A-DInSAR techniques confirmed to be a reliable tool in monitoring slow-moving landslides. In this case 96 ENVIronmental SATellite-Advanced Synthetic Aperture Radar (ENVISAT-ASAR) images, in ascending and descending orbits, have been processed using SUBSOFT software, developed by the Remote Sensing Laboratory (RSLab) group from the Universitat Politècnica de Catalunya (UPC). The DInSAR results, coupled with field survey, supported the analysis of the instability mechanism and confirmed the historical record of the movements already available for the town. - Highlights: • DInSAR confirmed to be a reliable tool in monitoring slow-moving landslides. • Integration with traditional monitoring systems is crucial for DInSAR application. • DInSAR data can be used for the natural risk mitigation related to landslides.

  1. Measurement of slow-moving along-track displacement from an efficient multiple-aperture SAR interferometry (MAI) stacking (United States)

    Jo, Min-Jeong; Jung, Hyung-Sup; Won, Joong-Sun; Poland, Michael; Miklius, Asta; Lu, Zhong


    Multiple-aperture SAR interferometry (MAI) has demonstrated outstanding measurement accuracy of along-track displacement when compared to pixel-offset-tracking methods; however, measuring slow-moving (cm/year) surface displacement remains a challenge. Stacking of multi-temporal observations is a potential approach to reducing noise and increasing measurement accuracy, but it is difficult to achieve a significant improvement by applying traditional stacking methods to multi-temporal MAI interferograms. This paper proposes an efficient MAI stacking method, where multi-temporal forward- and backward-looking residual interferograms are individually stacked before the MAI interferogram is generated. We tested the performance of this method using ENVISAT data from Kīlauea Volcano, Hawai‘i, where displacement on the order of several centimeters per year is common. By comparing results from the proposed stacking methods with displacements from GPS data, we documented measurement accuracies of about 1.03 and 1.07 cm/year for the descending and ascending tracks, respectively—an improvement of about a factor of two when compared with that from the conventional stacking approach. Three-dimensional surface-displacement maps can be constructed by combining stacked InSAR and MAI observations, which will contribute to a better understanding of a variety of geological phenomena.

  2. Real Aperture Radar interferometry as a tool for buildings vibration monitoring: Limits and potentials from an experimental study (United States)

    Luzi, Guido; Monserrat, Oriol; Crosetto, Michele


    In the last decade several researchers have dealt with the potential of radar interferometry as a remote sensing tool able to provide measurements of vibrations of large structures. More recently the technique has been consolidated thanks to the recent introduction on the market of specifically devoted radar instruments. Exploiting the interferometric capability of coherent radar, successful monitoring of bridges, towers and wind turbine powers has been achieved. This technique allowed looking at the frequency behaviour of civil structures and estimating their amplitude of displacement in the order of fraction of millimetres. The activity here described reports the results of an experimental investigation aimed at evaluating the effectiveness of a coherent Real-Aperture-Radar sensor to estimate the vibration of buildings in an urban environment, through an ambient vibration testing, where the expected amplitude vibration spans within a few to some tens of microns. Critical aspects affecting the retrieval of this information are here discussed, on the basis of some experimental data collected in the last year with a microwave interferometer working at Ku band and available on the market. Preliminary results are shown and suggestions related to the measurement procedures are discussed.

  3. Application of synthetic aperture radar interferometry for mine subsidence monitoring in the western United States (United States)

    Wempen, Jessica Michelle

    Differential Interferometric Synthetic Aperture Radar (DInSAR), a satellite-based remote sensing technique, is a practical method for measuring deformation of the earth's surface. In this investigation, the application of DInSAR for monitoring mine subsidence was evaluated for active underground mining regions in the Green River Basin in southwest Wyoming and the Wasatch Plateau in central Utah. Interferograms were generated using X-band (3-cm wavelength) Synthetic Aperture Radar data from the TerraSAR-X mission and L-band (24-cm wavelength) Synthetic Aperture Radar data from the Advanced Land Observing Satellite. In general, the DInSAR data have high spatial and temporal resolutions and show gradual, progressive subsidence. In the Green River Basin, displacements were estimated using both L-band and X-band data. In the Wasatch Plateau, displacements were only estimated using L-band data; areas affected by subsidence are identifiable in the X-band data, but precisely quantifying subsidence magnitudes is difficult as a result of significant phase noise. In the Green River Basin, the maximum subsidence magnitude was 150 cm over 690 days, estimated using L-band DInSAR. In the Wasatch Plateau, the maximum subsidence magnitude was 180 cm over 414 days. In both regions, as a result of low coherence in the areas with large displacements, the maximum displacements may be underestimated by tens of centimeters. Additionally, relationships between surface deformations measured by DInSAR and mining-induced seismicity (MIS) in the Green River Basin and the Wasatch Plateau were explored. Both regions exhibit large magnitude, relatively rapid subsidence, but the characteristics (rates and magnitudes) of MIS in the Wasatch Plateau study region and the Green River Basin are significantly different. In the Wasatch Plateau study region, surface displacements tend to precede seismicity, event rates tend to be high, and event magnitudes tend to be relatively low. In the Green River

  4. On the importance of path for phase unwrapping in synthetic aperture radar interferometry. (United States)

    Osmanoglu, Batuhan; Dixon, Timothy H; Wdowinski, Shimon; Cabral-Cano, Enrique


    Phase unwrapping is a key procedure in interferometric synthetic aperture radar studies, translating ambiguous phase observations to topography, and surface deformation estimates. Some unwrapping algorithms are conducted along specific paths based on different selection criteria. In this study, we analyze six unwrapping paths: line scan, maximum coherence, phase derivative variance, phase derivative variance with branch-cut, second-derivative reliability, and the Fisher distance. The latter is a new path algorithm based on Fisher information theory, which combines the phase derivative with the expected variance to get a more robust path, potentially performing better than others in the case of low image quality. In order to compare only the performance of the paths, the same unwrapping function (phase derivative integral) is used. Results indicate that the Fisher distance algorithm gives better results in most cases.

  5. Diffraction-limited Speckle-Masking Interferometry of the Red Supergiant VY CMa

    CERN Document Server

    Wittkowski, M; Weigelt, G


    We present the first diffraction-limited images of the mass-loss envelope of the red supergiant star VY CMa. The two-dimensional optical and NIR images were reconstructed from 3.6 m telescope speckle data using bispectrum speckle interferometry. At the wavelengths ~0.8 \\mum (RG 780 filter), 1.28 \\mum, and 2.17 \\mum the diffraction-limited resolutions of 46 mas, 73 mas, and 124 mas were achieved. All images clearly show that the circumstellar envelope of VY CMa is non-spherical. The RG 780, 1.28 \\mum, and 2.17 mum FWHM Gauss fit diameters are 67 mas * 83 mas, 80 mas * 116 mas and 138 mas * 205 mas, respectively, or 100 AU * 125 AU, 120 AU * 174 AU and 207 AU * 308 AU (for a distance of 1500 pc). We discuss several interpretations for the asymmetric morphology. Combining recent results about the angular momentum evolution of red supergiants and their pulsational properties, we suggest that VY CMa is an immediate progenitor of IRC +10420, a post red supergiant during its transformation into a Wolf-Rayet star.

  6. Apodized phase mask coronagraphs for arbitrary apertures. II. Comprehensive review of solutions for the vortex coronagraph

    CERN Document Server

    Carlotti, Alexis; Mawet, Dimitri


    With a clear circular aperture, the vortex coronagraph perfectly cancels an on-axis point source and offers a 0.9 or 1.75 lambda/D inner working angle for topological charge 2 or 4, respectively. Current and near-future large telescopes are on-axis, however, and the diffraction effects of the central obscuration, and the secondary supports are strong enough to prevent the detection of companions 1e-3 - 1e-5 as bright as, or fainter than, their host star. Recent advances show that a ring apodizer can restore the performance of this coronagraph by compensating for the diffraction effects of a circular central obscuration in a 1D modeling of the pupil. We extend this work and optimize apodizers for arbitrary apertures in 2D in order to tackle the diffraction effects of the spiders and other noncircular artefacts in the pupil. We use a numerical optimization scheme to compute hybrid coronagraph designs that combine the advantages of the vortex coronagraph (small in IWA) and of shaped pupils coronagraphs (robustne...

  7. Unveiling the near-infrared structure of the massive-young stellar object NGC 3603 IRS 9A* with sparse aperture masking and spectroastrometry (United States)

    Sanchez-Bermudez, J.; Hummel, C. A.; Tuthill, P.; Alberdi, A.; Schödel, R.; Lacour, S.; Stanke, T.


    Context. Contemporary theory holds that massive stars gather mass during their initial phases via accreting disk-like structures. However, conclusive evidence for disks has remained elusive for most massive young objects. This is mainly due to significant observational challenges: objects are rare and located at great distances within dusty, highly opaque environments. Incisive studies, even targeting individual objects, are therefore relevant to the progression of the field. NGC 3603 IRS 9A* is a young massive stellar object that is still surrounded by an envelope of molecular gas for which previous mid-infrared observations with long-baseline interferometry have provided evidence of a plausible disk of 50 mas diameter at its core. Aims: This work aims at a comprehensive study of the physics and morphology of IRS 9A at near-infrared wavelengths. Methods: New sparse aperture-masking interferometry data, taken with the near-infrared camera NACO of the Very Large Telescope (VLT) at Ks and L' wavelengths, were analyzed together with archival high-resolution H2 and Brγ lines obtained with the cryogenic high-resolution infrared schelle spectrograph (CRIRES). Results: The trends in the calibrated visibilities at Ks and L'-bands suggest the presence of a partially resolved compact object with an angular size of ≤30 mas at the core of IRS 9A, together with the presence of over-resolved flux. The spectroastrometric signal of the H2 line, obtained from the CRIRES spectra, shows that this spectral feature proceeds from the large-scale extended emission (~300 mas), while the Brγ line appears to be formed at the core of the object (~20 mas). To better understand the physics that drive IRS 9A, we have performed continuum radiative transfer modeling. Our best model supports the existence of a compact disk with an angular diameter of 20 mas, together with an outer envelope of 1'' exhibiting a polar cavity with an opening angle of ~30°. This model reproduces the MIR morphology

  8. Astronomical Optical Interferometry. I. Methods and Instrumentation

    Directory of Open Access Journals (Sweden)

    Jankov, S.


    Full Text Available Previous decade has seen an achievement of large interferometricprojects including 8-10m telescopes and 100m class baselines. Modern computerand control technology has enabled the interferometric combination of lightfrom separate telescopes also in the visible and infrared regimes. Imagingwith milli-arcsecond (mas resolution and astrometry with micro-arcsecond($mu$as precision have thus become reality. Here, I review the methods andinstrumentation corresponding to the current state in the field ofastronomical optical interferometry. First, this review summarizes thedevelopment from the pioneering works of Fizeau and Michelson. Next, thefundamental observables are described, followed by the discussion of the basicdesign principles of modern interferometers. The basic interferometrictechniques such as speckle and aperture masking interferometry, aperture synthesisand nulling interferometry are disscused as well. Using the experience ofpast and existing facilities to illustrate important points, I considerparticularly the new generation of large interferometers that has beenrecently commissioned (most notably, the CHARA, Keck, VLT and LBTInterferometers. Finally, I discuss the longer-term future of opticalinterferometry, including the possibilities of new large-scale ground-based projects and prospects for space interferometry.

  9. Instruments of RT-2 Experiment onboard CORONASPHOTON and their test and evaluation III: Coded Aperture Mask and Fresnel Zone Plates in RT-2/CZT Payload

    CERN Document Server

    Nandi, Anuj; Debnath, D; Chakrabarti, Sandip K; Kotoch, T B; Sarkar, R; Yadav, Vipin K; Girish, V; Rao, A R; Bhattacharya, D; 10.1007/s10686-010-9184-3


    Imaging in hard X-rays of any astrophysical source with high angular resolution is a challenging job. Shadow-casting technique is one of the most viable options for imaging in hard X-rays. We have used two different types of shadow-casters, namely, Coded Aperture Mask (CAM) and Fresnel Zone Plate (FZP) pair and two types of pixellated solid-state detectors, namely, CZT and CMOS in RT-2/CZT payload, the hard X-ray imaging instrument onboard the CORONAS-PHOTON satellite. In this paper, we present the results of simulations with different combinations of coders (CAM & FZP) and detectors that are employed in the RT-2/CZT payload. We discuss the possibility of detecting transient Solar flares with good angular resolution for various combinations. Simulated results are compared with laboratory experiments to verify the consistency of the designed configuration.

  10. Error analysis in the digital elevation model of Kuwait desert derived from repeat pass synthetic aperture radar interferometry (United States)

    Rao, Kota S.; Al Jassar, Hala K.


    The aim of this paper is to analyze the errors in the Digital Elevation Models (DEMs) derived through repeat pass SAR interferometry (InSAR). Out of 29 ASAR images available to us, 8 are selected for this study which has unique data set forming 7 InSAR pairs with single master image. The perpendicular component of baseline (B highmod) varies between 200 to 400 m to generate good quality DEMs. The Temporal baseline (T) varies from 35 days to 525 days to see the effect of temporal decorrelation. It is expected that all the DEMs be similar to each other spatially with in the noise limits. However, they differ very much with one another. The 7 DEMs are compared with the DEM of SRTM for the estimation of errors. The spatial and temporal distribution of errors in the DEM is analyzed by considering several case studies. Spatial and temporal variability of precipitable water vapour is analysed. Precipitable water vapour (PWV) corrections to the DEMs are implemented and found to have no significant effect. The reasons are explained. Temporal decorrelation of phases and soil moisture variations seem to have influence on the accuracy of the derived DEM. It is suggested that installing a number of corner reflectors (CRs) and the use of Permanent Scatter approach may improve the accuracy of the results in desert test sites.

  11. Detecting Faults in Southern California using Computer-Vision Techniques and Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) Interferometry (United States)

    Barba, M.; Rains, C.; von Dassow, W.; Parker, J. W.; Glasscoe, M. T.


    Knowing the location and behavior of active faults is essential for earthquake hazard assessment and disaster response. In Interferometric Synthetic Aperture Radar (InSAR) images, faults are revealed as linear discontinuities. Currently, interferograms are manually inspected to locate faults. During the summer of 2013, the NASA-JPL DEVELOP California Disasters team contributed to the development of a method to expedite fault detection in California using remote-sensing technology. The team utilized InSAR images created from polarimetric L-band data from NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) project. A computer-vision technique known as 'edge-detection' was used to automate the fault-identification process. We tested and refined an edge-detection algorithm under development through NASA's Earthquake Data Enhanced Cyber-Infrastructure for Disaster Evaluation and Response (E-DECIDER) project. To optimize the algorithm we used both UAVSAR interferograms and synthetic interferograms generated through Disloc, a web-based modeling program available through NASA's QuakeSim project. The edge-detection algorithm detected seismic, aseismic, and co-seismic slip along faults that were identified and compared with databases of known fault systems. Our optimization process was the first step toward integration of the edge-detection code into E-DECIDER to provide decision support for earthquake preparation and disaster management. E-DECIDER partners that will use the edge-detection code include the California Earthquake Clearinghouse and the US Department of Homeland Security through delivery of products using the Unified Incident Command and Decision Support (UICDS) service. Through these partnerships, researchers, earthquake disaster response teams, and policy-makers will be able to use this new methodology to examine the details of ground and fault motions for moderate to large earthquakes. Following an earthquake, the newly discovered faults can

  12. Sparse aperture masking at the VLT II. Detection limits for the eight debris disks stars $\\beta$ Pic, AU Mic, 49 Cet, $\\eta$ Tel, Fomalhaut, g Lup, HD181327 and HR8799

    CERN Document Server

    Gauchet, L; Lagrange, A -M; Ehrenreich, D; Bonnefoy, M; Girard, J H; Boccaletti, A


    Context. The formation of planetary systems is a common, yet complex mechanism. Numerous stars have been identified to possess a debris disk, a proto-planetary disk or a planetary system. The understanding of such formation process requires the study of debris disks. These targets are substantial and particularly suitable for optical and infrared observations. Sparse Aperture masking (SAM) is a high angular resolution technique strongly contributing to probe the region from 30 to 200 mas around the stars. This area is usually unreachable with classical imaging, and the technique also remains highly competitive compared to vortex coronagraphy. Aims. We aim to study debris disks with aperture masking to probe the close environment of the stars. Our goal is either to find low mass companions, or to set detection limits. Methods. We observed eight stars presenting debris disks ( $\\beta$ Pictoris, AU Microscopii, 49 Ceti, $\\eta$ Telescopii, Fomalhaut, g Lupi, HD181327 and HR8799) with SAM technique on the NaCo ins...

  13. Novel Polarimetric SAR Interferometry Algorithms Project (United States)

    National Aeronautics and Space Administration — Polarimetric SAR interferometry (PolInSAR) is a recently developed synthetic aperture radar (SAR) imaging mode that combines the capabilities of radar polarimetry...

  14. High-contrast Nulling Interferometry Techniques Project (United States)

    National Aeronautics and Space Administration — "We are developing rotating-baseline nulling-interferometry techniques and algorithms on the single-aperture Hale and Keck telescopes at near-infrared wavelengths,...

  15. Sparse aperture masking at the VLT. II. Detection limits for the eight debris disks stars β Pic, AU Mic, 49 Cet, η Tel, Fomalhaut, g Lup, HD 181327 and HR 8799 (United States)

    Gauchet, L.; Lacour, S.; Lagrange, A.-M.; Ehrenreich, D.; Bonnefoy, M.; Girard, J. H.; Boccaletti, A.


    Context. The formation of planetary systems is a common, yet complex mechanism. Numerous stars have been identified to possess a debris disk, a proto-planetary disk or a planetary system. The understanding of such formation process requires the study of debris disks. These targets are substantial and particularly suitable for optical and infrared observations. Sparse aperture masking (SAM) is a high angular resolution technique strongly contributing to probing the region from 30 to 200 mas around the stars. This area is usually unreachable with classical imaging, and the technique also remains highly competitive compared to vortex coronagraphy. Aims: We aim to study debris disks with aperture masking to probe the close environment of the stars. Our goal is either to find low-mass companions, or to set detection limits. Methods: We observed eight stars presenting debris disks (β Pictoris, AU Microscopii, 49 Ceti, η Telescopii, Fomalhaut, g Lupi, HD 181327, and HR 8799) with SAM technique on the NaCo instrument at the Very Large Telescope (VLT). Results: No close companions were detected using closure phase information under 0.5'' of separation from the parent stars. We obtained magnitude detection limits that we converted to Jupiter masses detection limits using theoretical isochrones from evolutionary models. Conclusions: We derived upper mass limits on the presence of companions in the area of a few times the telescope's diffraction limits around each target star. Based on observations collected at the European Southern Observatory (ESO) during runs 087.C-0450(A), 087.C-0450(B) 087.C-0750(A), 088.C-0358(A).All magnitude detection limits maps are only available at the CDS via anonymous ftp to ( or via

  16. The Palomar Kernel Phase Experiment: Testing Kernel Phase Interferometry for Ground-based Astronomical Observations

    CERN Document Server

    Pope, Benjamin; Hinkley, Sasha; Ireland, Michael J; Greenbaum, Alexandra; Latyshev, Alexey; Monnier, John D; Martinache, Frantz


    At present, the principal limitation on the resolution and contrast of astronomical imaging instruments comes from aberrations in the optical path, which may be imposed by the Earth's turbulent atmosphere or by variations in the alignment and shape of the telescope optics. These errors can be corrected physically, with active and adaptive optics, and in post-processing of the resulting image. A recently-developed adaptive optics post-processing technique, called kernel phase interferometry, uses linear combinations of phases that are self-calibrating with respect to small errors, with the goal of constructing observables that are robust against the residual optical aberrations in otherwise well-corrected imaging systems. Here we present a direct comparison between kernel phase and the more established competing techniques, aperture masking interferometry, point spread function (PSF) fitting and bispectral analysis. We resolve the alpha Ophiuchi binary system near periastron, using the Palomar 200-Inch Telesco...

  17. The life of massive stars seen through optical/infrared interferometry (United States)

    Sanchez-Bermudez, J.; Alberdi, A.; Schödel, R.


    During the last decade, optical/infrared interferometry has become an essential tool to contribute to the understanding of stellar astrophysics. We present our results in the study of different aspects in the life of massive stars using optical interferometry. Particularly, we focused the discussion in our findings about multiplicity, interactions of the massive stars with the interstellar medium, and the early stages of high-mass stars. Our near-infrared observations comprise both: (i) long-baseline interferometry making use of AMBER/VLTI, and (ii) sparse aperture masking with VLT/NACO/SAM. These data have been obtained by our research group in the previous years, and the results have been published in several peer-reviewed papers. The principles of the optical/near-infrared interferometry are briefly presented. Particularly, we describe how to get the calibrated Interferometric observables. Henceforth, we present our results of two massive systems (HD150136 and Herschel 36) for which we discovered their triple nature using AMBER/VLTI. Finally, we will present the recently found evidence of a disk and a binary system in a very massive young stellar object known as IRS 9A in the NGC 3603 region.

  18. Detection of small, slow ground targets using Synthetic Aperture Radar (United States)

    Chen, Curtis; Chapin, Elaine; Rosen, Paul


    Synthetic aperture radar (SAR) along-track interferometry (ATI) is a technique for sensing Earth-surface motion. The technique involves interferometrically combining data from two radar images acquired from phase centers separated along the platform flight track.

  19. Optimal pupil apodizations for arbitrary apertures

    CERN Document Server

    Carlotti, A; Kasdin, N J


    We present here fully optimized two-dimensional pupil apodizations for which no specific geometric constraints are put on the pupil plane apodization, apart from the shape of the aperture itself. Masks for circular and segmented apertures are displayed, with and without central obstruction and spiders. Examples of optimal masks are shown for Subaru, SPICA and JWST. Several high-contrast regions are considered with different sizes, positions, shapes and contrasts. It is interesting to note that all the masks that result from these optimizations tend to have a binary transmission profile.

  20. In-focus phase retrieval using JWST-NIRISS's non-redundant mask (United States)

    Greenbaum, Alexandra Z.; Gamper, Noah; Sivaramakrishnan, Anand


    The James Webb Space Telescope's Near InfraRed Imager and Slitless Spectrograph (NIRISS) contains a 7-hole non-redundant mask (NRM) in its pupil. NIRISS's Aperture Masking Interferometry (AMI) mode is useful both for science as well as wavefront sensing. In-focus science detector NRM and full pupil images of unresolved stars can be used to measure the wavefront without any dedicated wavefront sensing hardware or any moving mirrors. Using routine science operational sequences, these images can be taken before or after any science visit. NRM fringe phases constrain Gerchberg-Saxton phase retrieval to disambiguate the algorithm's two-fold degeneracy. We summarize how consecutive masked and unmasked exposures provide enough information to reconstruct a wavefront with up to ˜1-2 rms radians of error. We present our latest progress on using this approach on laboratory experiments, and discuss those results in the context of contingency for JWST segment phasing. We discuss extending our method to ground-based AO systems and future space telescopes.

  1. Extinction controlled adaptive phase-mask coronagraph

    CERN Document Server

    Bourget, P; Mawet, D; Haguenauer, P


    Context. Phase-mask coronagraphy is advantageous in terms of inner working angle and discovery space. It is however still plagued by drawbacks such as sensitivity to tip-tilt errors and chromatism. A nulling stellar coronagraph based on the adaptive phase-mask concept using polarization interferometry is presented in this paper. Aims. Our concept aims at dynamically and achromatically optimizing the nulling efficiency of the coronagraph, making it more immune to fast low-order aberrations (tip-tilt errors, focus, ...). Methods. We performed numerical simulations to demonstrate the value of the proposed method. The active control system will correct for the detrimental effects of image instabilities on the destructive interference. The mask adaptability both in size, phase and amplitude also compensates for manufacturing errors of the mask itself, and potentially for chromatic effects. Liquid-crystal properties are used to provide variable transmission of an annulus around the phase mask, but also to achieve t...

  2. Aperture Synthesis Methods and Applications to Optical Astronomy

    CERN Document Server

    Saha, Swapan Kumar


    Over the years long baseline optical interferometry has slowly gained in importance and today it is a powerful tool. This timely book sets out to highlight the basic principles of long baseline optical interferometry. The book addresses the fundamentals of stellar interferometry with emphasis on aperture synthesis using an array of telescopes particularly at optical/IR wavelengths. It discusses the fundamentals of electromagnetic fields, wave optics, interference, diffraction, and imaging at length. There is a chapter dedicated to radio and intensity interferometry corroborating with basic mathematical steps. The basic principle of optical interferometry and its requirements, its limitations and the technical challenges it poses, are also covered in depth. Assisted by illustrations and footnotes, the book examines the basic tricks of the trade, current trends and methods, and it points to the potential of true interferometry both from the ground and space.

  3. Clay Mask Workshop (United States)

    Gamble, David L.


    Masks can represent so many things, such as emotions (happy, sad, fearful) and power. The familiar "comedy and tragedy" masks, derived from ancient Greek theater, are just one example from mask history. Death masks from the ancient Egyptians influenced the ancient Romans into creating similar masks for their departed. Masks can represent many…

  4. Temporal decorrelation model for the bistatic SAR interferometry

    Institute of Scientific and Technical Information of China (English)

    Qilei Zhang; Wenge Chang


    This paper develops a temporal decorrelation model for the bistatic synthetic aperture radar (BSAR) interferometry. The temporal baseline is one of the important decorrelation sources for the repeat-pass synthetic aperture radar (SAR) interferometry. The study of temporal decorrelation is chal enging, especial y for the bistatic configuration, since temporal decorrelation is related to the data acquisition geometry. To develop an appropriate theoretical model for BSAR interferometry, the existing models for monostatic SAR cases are extended, and the general BSAR geometry con-figuration is involved in the derivation. Therefore, the developed temporal decorrelation model can be seen as a general model. The validity of the theoretical model is supported by Monte Carlo simulations. Furthermore, the impacts of the system parameters and BSAR geometry configurations on the temporal decorrelation model are discussed briefly.

  5. Direct 3D printed shadow mask on Silicon (United States)

    Rahiminejad, S.; Köhler, E.; Enoksson, P.


    A 3D printed shadow mask method is presented. The 3D printer prints ABS plastic directly on the wafer, thus avoiding gaps between the wafer and the shadow mask, and deformation during the process. The wafer together with the 3D printed shadow mask was sputtered with Ti and Au. The shadow mask was released by immersion in acetone. The sputtered patches through the shadow mask were compared to the opening of the 3D printed shadow mask and the design dimensions. The patterned Au patches were larger than the printed apertures, however they were smaller than the design widths. The mask was printed in 4 min, the cost is less than one euro cent, and the process is a low temperature process suitable for temperature sensitive components.

  6. Aperture area measurement facility (United States)

    Federal Laboratory Consortium — NIST has established an absolute aperture area measurement facility for circular and near-circular apertures use in radiometric instruments. The facility consists of...

  7. Parallel optical nanolithography using nanoscale bowtie apertures (United States)

    Uppuluri, Sreemanth M. V.

    Over the past two decades various branches of science and engineering have developed techniques for producing nanoscopic light sources for different applications such as imaging, detection and fabrication. These areas include near-field scanning optical microscopy (NSOM), surface-enhanced Raman scattering and detection (SERS), plasmonics and so on. In particular nanolithography techniques have been developed to produce feature sizes in the sub-100 nm length scales. These processes include variations of standard photolithography process to achieve high resolution, optical fiber-based near-field lithography, surface plasmon assisted nanolithography, interference optical lithography and so on. This work presents a study of the viability of using nanoscale bowtie apertures for nanolithography. Bowtie apertures exhibit a unique property of supporting a propagating TE10 mode at wavelengths of light in the visible and near-UV regimes. The energy of this mode is concentrated in the gap region of the aperture and thus these apertures have the potential to produce high intensity nanoscale light spots that can be used for nano-patterning applications. We demonstrate this capability of nanoscale bowtie apertures by patterning photoresist to obtain resolution less than 100 nm. Initially we present the results from static lithography experiments and show that the ridge apertures of different shapes -- C, H and bowtie produce holes in the photoresist of dimensions around 50-60 nm. Subsequently we address the issues involved in using these apertures for nano directwriting. We show that chromium thin-films offer a viable solution to produce high quality metal films of surface roughness less than 1 nm over an area of 25 mum2. This is indeed important to achieve intimate contact between the apertures and the photoresist surface. We also explain ways to decrease friction between the mask and photoresist surfaces during nano direct-writing. In addition, to decrease the contact force

  8. A system for airborne SAR interferometry

    DEFF Research Database (Denmark)

    Madsen, Søren Nørvang; Skou, Niels; Granholm, Johan


    Interferometric synthetic aperture radar (INSAR) systems have already demonstrated that elevation maps can be generated rapidly with single pass airborne across-track interferometry systems (XTT), and satellite repeat track interferometry (RTT) techniques have been used to map both elevation...... and perturbations of the surface of the Earth. The Danish Center for Remote Sensing (DCRS) has experimented with airborne INSAR since 1993. Multiple track data are collected in a special mode in which the radar directly steers the aircraft which allows for very precise control of the flight path. Such data sets...... have been acquired at both L- and C-band. During 1994/95 the system was further modified to add the capability to perform single pass interferometric data acquisitions at C-band. This paper will discuss: (1) the general principles of INSAR systems and their application to topographic mapping and (2...

  9. High-performance 3D waveguide architecture for astronomical pupil-remapping interferometry. (United States)

    Norris, Barnaby; Cvetojevic, Nick; Gross, Simon; Jovanovic, Nemanja; Stewart, Paul N; Charles, Ned; Lawrence, Jon S; Withford, Michael J; Tuthill, Peter


    The detection and characterization of extra-solar planets is a major theme driving modern astronomy. Direct imaging of exoplanets allows access to a parameter space complementary to other detection methods, and potentially the characterization of exoplanetary atmospheres and surfaces. However achieving the required levels of performance with direct imaging from ground-based telescopes (subject to Earth's turbulent atmosphere) has been extremely challenging. Here we demonstrate a new generation of photonic pupil-remapping devices which build upon the Dragonfly instrument, a high contrast waveguide-based interferometer. This new generation overcomes problems caused by interference from unguided light and low throughput. Closure phase measurement scatter of only ∼ 0.2° has been achieved, with waveguide throughputs of > 70%. This translates to a maximum contrast-ratio sensitivity between star and planet at 1λ/D (1σ detection) of 5.3 × 10(-4) (with a conventional adaptive-optics system) or 1.8 × 10(-4) (with 'extreme-AO'), improving even further when random error is minimized by averaging over multiple exposures. This is an order of magnitude beyond conventional pupil-segmenting interferometry techniques (such as aperture masking), allowing a previously inaccessible part of the star to planet contrast-separation parameter space to be explored.

  10. Mid-infrared interferometry of the massive young stellar object NGC3603 - IRS 9A

    CERN Document Server

    Vehoff, S; Monnier, J D; Tuthill, P; Nuernberger, D E A; Siebenmorgen, R; Chesneau, O; Duschl, W J


    We present observations and models for one of these MYSO candidates, NGC3603 IRS 9A. Our goal is to investigate with infrared interferometry the structure of IRS 9A on scales as small as 200AU, exploiting the fact that a cluster of O and B stars has blown away much of the obscuring foreground dust and gas. Observations in the N-band were carried out with the MIDI beam combiner attached to the VLTI. Additional interferometric observations which probe the structure of IRS 9A on larger scales were performed with an aperture mask installed in the T-ReCS instrument of Gemini South. The spectral energy distribution (SED) is constrained by the MIDI N-band spectrum and by data from the Spitzer Space Telescope. Our efforts to model the structure and SED of IRS 9A range from simple geometrical models of the brightness distribution to one- and two-dimensional radiative transfer computations. The target is resolved by T-ReCS, with an equivalent (elliptical) Gaussian width of 330mas by 280mas (2300 AU by 2000 AU). Despite...

  11. High performance 3D waveguide architecture for astronomical pupil-remapping interferometry (United States)

    Gross, Simon; Norris, Barnaby R.; Cvetojevic, Nick; Jovanovic, Nemanja; Arriola Martiarena, Alexander; Stewart, Paul N.; Lawrence, Jon S.; Withford, Michael J.; Tuthill, Peter G.


    Here we demonstrate a new generation of photonic pupil-remapping devices which build upon the interferometric framework developed for the Dragonfly instrument: a high contrast waveguide-based device which recovers robust complex visibility observables. New generation Dragonfly devices overcome problems caused by interference from unguided light and low throughput, promising unprecedented on-sky performance. Closure phase measurement scatter of only ~0.2° has been achieved, with waveguide throughputs of > 70%. This translates to a maximum contrast-ratio sensitivity (between the host star and its orbiting planet) at 1λ /D (1σ detection) of 5.3×10-4 (when a conventional adaptive-optics (AO) system is used) or 1.8×10-4 (for typical `extreme-AO' performance), improving even further when random error is minimised by averaging over multiple exposures. This is an order of magnitude beyond conventional pupil-segmenting interferometry techniques (such as aperture masking), allowing a previously inaccessible part of the star to planet contrast-separation parameter space to be explored.

  12. Aperture optical antennas

    CERN Document Server

    Wenger, Jerome


    This contribution reviews the studies on subwavelength aperture antennas in the optical regime, paying attention to both the fundamental investigations and the applications. Section 2 reports on the enhancement of light-matter interaction using three main types of aperture antennas: single subwavelength aperture, single aperture surrounded by shallow surface corrugations, and subwavelength aperture arrays. A large fraction of nanoaperture applications is devoted to the field of biophotonics to improve molecular sensing, which are reviewed in Section 3. Lastly, the applications towards nano-optics (sources, detectors and filters) are discussed in Section 4.

  13. Mask degradation monitoring with aerial mask inspector (United States)

    Tseng, Wen-Jui; Fu, Yung-Ying; Lu, Shih-Ping; Jiang, Ming-Sian; Lin, Jeffrey; Wu, Clare; Lifschitz, Sivan; Tam, Aviram


    As design rule continues to shrink, microlithography is becoming more challenging and the photomasks need to comply with high scanner laser energy, low CDU, and ever more aggressive RETs. This give rise to numerous challenges in the semiconductor wafer fabrication plants. Some of these challenges being contamination (mainly haze and particles), mask pattern degradation (MoSi oxidation, chrome migration, etc.) and pellicle degradation. Fabs are constantly working to establish an efficient methodology to manage these challenges mainly using mask inspection, wafer inspection, SEM review and CD SEMs. Aerial technology offers a unique opportunity to address the above mask related challenges using one tool. The Applied Materials Aera3TM system has the inherent ability to inspect for defects (haze, particles, etc.), and track mask degradation (e.g. CDU). This paper focuses on haze monitoring, which is still a significant challenge in semiconductor manufacturing, and mask degradation effects that are starting to emerge as the next challenge for high volume semiconductor manufacturers. The paper describes Aerial inspector (Aera3) early haze methodology and mask degradation tracking related to high volume manufacturing. These will be demonstrated on memory products. At the end of the paper we take a brief look on subsequent work currently conducted on the more general issue of photo mask degradation monitoring by means of an Aerial inspector.

  14. Plasmonic interferometry: probing launching dipoles in scanning-probe plasmonics

    CERN Document Server

    Mollet, O; Genet, C; Huant, S; Drezet, A


    We develop a semi-analytical method for analyzing surface plasmon interferometry using near-field scanning optical sources. We compare our approach to Young double hole interferometry experiments using scanning tunneling microscope (STM) discussed in the literature and realize experiments with an aperture near-field scanning optical microscope (NSOM) source positioned near a ring like aperture slit milled in a thick gold film. In both cases the agreement between experiments and model is very good. We emphasize the role of dipole orientations and discuss the role of magnetic versus electric dipole contributions to the imaging process as well as the directionality of the effective dipoles associated with the various optical and plasmonic sources.

  15. Radio & Optical Interferometry: Basic Observing Techniques and Data Analysis

    CERN Document Server

    Monnier, John D


    Astronomers usually need the highest angular resolution possible, but the blurring effect of diffraction imposes a fundamental limit on the image quality from any single telescope. Interferometry allows light collected at widely-separated telescopes to be combined in order to synthesize an aperture much larger than an individual telescope thereby improving angular resolution by orders of magnitude. Radio and millimeter wave astronomers depend on interferometry to achieve image quality on par with conventional visible and infrared telescopes. Interferometers at visible and infrared wavelengths extend angular resolution below the milli-arcsecond level to open up unique research areas in imaging stellar surfaces and circumstellar environments. In this chapter the basic principles of interferometry are reviewed with an emphasis on the common features for radio and optical observing. While many techniques are common to interferometers of all wavelengths, crucial differences are identified that will help new practi...

  16. Fully Optimized Shaped Pupils for Arbitrary Apertures (United States)

    Carlotti, Alexis; Vanderbei, R.; Kasdin, N. J.; Che, G.


    Optimal apodization masks for monolithic and segmented apertures are presented, with and without central obstruction and spider vanes. Examples of optimal masks are shown for several ground-based telescopes (The Subaru, Keck, Gemini, Palomar and Very Large telescopes). We also discuss the case of extremely large telescopes. Various high-contrast regions are considered with different inner and outer working angles, shapes and contrasts. These parameters are chosen to fit the specific constraints of each instrument, in particular those set by the dedicated coronagraphic adaptive optics system. Because of the limited size of the high-contrast regions, all the masks that result from these optimizations tend to have binary transmissions, and are thus as achromatic as previous shaped pupils. Effort is put on obtaining structurally connected masks. We intend to test these new shaped pupils in Princeton's high-contrast imaging laboratory, and to this end we explore different techniques to make the masks, such as cutting them in a metal layer, laying them on a glass substrate, or using a MOEMS device.

  17. Mask industry assessment: 2004 (United States)

    Shelden, Gilbert V.; Hector, Scott D.


    Microelectronics industry leaders routinely name mask cost and cycle time as top issues of concern. A survey was created with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of mask technologists from semiconductor manufacturers, merchant mask suppliers, and makers of equipment for mask fabrication. This year's assessment is the third in the current series of annual reports and is intended to be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the mask industry. This report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results may be used to guide future investments on critical path issues. This year's survey builds upon the 2003 survey to provide an ongoing database using the same questions as a baseline with only a few minor changes or additions. Questions are grouped into categories: general business profile information, data processing, yields and yield loss mechanisms, delivery times, returns and services. Within each category are a many questions that create a detailed profile of both the business and technical status of the mask industry. This assessment includes inputs from ten major global merchant and captive mask manufacturers whose revenue represents approximately 85% of the global mask market.

  18. Analyzing EUV mask costs (United States)

    Lercel, Michael; Kasprowicz, Bryan


    The introduction of Extreme Ultraviolet Lithography (EUV) as a replacement for multiple patterning is based on improvements of cycle time, yield, and cost. Earlier cost studies have assumed a simple assumption that EUV masks (being more complex with the multilayer coated blank) are not more than three times as expensive as advanced ArFi (ArF immersion) masks. EUV masks are expected to be more expensive during the ramp of the technology because of the added cost of the complex mask blank, the use of EUV specific mask tools, and a ramp of yield learning relative to the more mature technologies. This study concludes that, within a range of scenarios, the hypothesis that EUV mask costs are not more than three times that of advanced ArFi masks is valid and conservative.

  19. Mask industry assessment: 2003 (United States)

    Kimmel, Kurt R.


    Microelectronics industry leaders routinely name mask technology and mask supply issues of cost and cycle time as top issues of concern. A survey was initiated in 2002 with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition.1 This paper presents the results of the second annual survey which is an enhanced version of the inaugural survey building upon its strengths and improving the weak points. The original survey was designed with the input of member company mask technologists, merchant mask suppliers, and industry equipment makers. The assessment is intended to be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the critical mask industry. An objective is to create a valuable reference to identify strengths and opportunities and to guide investments on critical-path issues. As subsequent years are added, historical profiles can also be created. This assessment includes inputs from ten major global merchant and captive mask manufacturers representing approximately 80% of the global mask market (using revenue as the measure) and making this the most comprehensive mask industry survey ever. The participating companies are: Compugraphics, Dai Nippon Printing, Dupont Photomask, Hoya, IBM, Infineon, Intel, Taiwan Mask Company, Toppan, and TSMC. Questions are grouped into five categories: General Business Profile Information; Data Processing; Yields and Yield loss Mechanisms; Delivery Time; and Returns and Services. Within each category are a multitude of questions that create a detailed profile of both the business and technical status of the mask industry.

  20. Binary mask programmable hologram. (United States)

    Tsang, P W M; Poon, T-C; Zhou, Changhe; Cheung, K W K


    We report, for the first time, the concept and generation of a novel Fresnel hologram called the digital binary mask programmable hologram (BMPH). A BMPH is comprised of a static, high resolution binary grating that is overlaid with a lower resolution binary mask. The reconstructed image of the BMPH can be programmed to approximate a target image (including both intensity and depth information) by configuring the pattern of the binary mask with a simple genetic algorithm (SGA). As the low resolution binary mask can be realized with less stringent display technology, our method enables the development of simple and economical holographic video display.

  1. Mask industry assessment: 2005 (United States)

    Shelden, Gilbert; Hector, Scott


    Microelectronics industry leaders routinely name mask cost and cycle time as top issues of concern. A survey was created with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of mask technologists from semiconductor manufacturers, merchant mask suppliers, and makers of equipment for mask fabrication. This year's assessment is the fourth in the current series of annual reports and is intended to be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the mask industry. This report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results may be used to guide future investments on critical path issues. This year's survey contains all of the 2004 survey questions to provide an ongoing database. Additional questions were added to the survey covering operating cost factors and equipment utilization. Questions are grouped into categories: general business profile information, data processing, yields and yield loss mechanisms, delivery times, returns and services, operating cost factors and equipment utilization. Within each category are a many questions that create a detailed profile of both the business and technical status of the mask industry. This assessment includes inputs from eight major global merchant and captive mask manufacturers whose revenue represents approximately 85% of the global mask market. This participation rate is reduced by one captive from 2004. Note: Toppan, DuPont Photomasks Inc and AMTC (new) were consolidated into one input therefore the 2004 and 2005 surveys are basically equivalent.

  2. Mastering Apple Aperture

    CERN Document Server

    Fitzgerald, Thomas


    Written in a conversational style, the author will share his knowledge on advanced Aperture topics with detailed discussions of advanced topics, the theory behind some of those topics and lots of hints and tips for ways to improve your workflow.Photographer's who have a basic understanding of Aperture

  3. How the global layout of the mask influences masking strength. (United States)

    Ghose, Tandra; Hermens, Frouke; Herzog, Michael H


    In visual backward masking, the perception of a target is influenced by a trailing mask. Masking is usually explained by local interactions between the target and the mask representations. However, recently it has been shown that the global spatial layout of the mask rather than its local structure determines masking strength (Hermens & Herzog, 2007). Here, we varied the mask layout by spatial, luminance, and temporal cues. We presented a vernier target followed by a mask with 25 elements. Performance deteriorated when the length of the two mask elements neighboring the target vernier was doubled. However, when the length of every second mask element was doubled, performance improved. When the luminance of the neighboring elements was doubled, performance also deteriorated but no improvement in performance was observed when every second element had a double luminance. For temporal manipulations, a complex nonmonotonic masking function was observed. Hence, changes in the mask layout by spatial, luminance, and temporal cues lead to highly different results.

  4. Theory of supervirtual refraction interferometry

    KAUST Repository

    Bharadwaj, Pawan


    Inverting for the subsurface velocity distribution by refraction traveltime tomography is a well-accepted imaging method by both the exploration and earthquake seismology communities. A significant drawback, however, is that the recorded traces become noisier with increasing offset from the source position, and so accurate picking of traveltimes in far-offset traces is often prevented. To enhance the signal-to-noise ratio (SNR) of the far-offset traces, we present the theory of supervirtual refraction interferometry where the SNR of far-offset head-wave arrivals can be theoretically increased by a factor proportional to; here, N is the number of receiver or source positions associated with the recording and generation of the head-wave arrival. There are two steps to this methodology: correlation and summation of the data to generate traces with virtual head-wave arrivals, followed by the convolution of the data with the virtual traces to create traces with supervirtual head-wave arrivals. This method is valid for any medium that generates head-wave arrivals recorded by the geophones. Results with both synthetic traces and field data demonstrate the feasibility of this method. There are at least four significant benefits of supervirtual interferometry: (1) an enhanced SNR of far-offset traces so the first-arrival traveltimes of the noisy far-offset traces can be more reliably picked to extend the useful aperture of the data, (2) the SNR of head waves in a trace that arrive later than the first arrival can be enhanced for accurate traveltime picking and subsequent inversion by later-arrival traveltime tomography, (3) common receiver-pair gathers can be analysed to detect the presence of diving waves in the first arrivals, which can be used to assess the nature of the refracting boundary, and (4) the source statics term is eliminated in the correlation operations so that the timing of the virtual traces is independent of the source excitation time. This suggests the

  5. Multi-part mask for implanting workpieces

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Aaron P.; Carlson, Charles T.


    A multi-part mask has a pattern plate, which includes a planar portion that has the desired aperture pattern to be used during workpiece processing. The multi-part mask also has a mounting frame, which is used to hold the pattern plate. Prior to assembly, the pattern plate has an aligning portion, which has one or more holes through which reusable alignment pins are inserted. These alignment pins enter kinematic joints disposed on the mounting frame, which serve to precisely align the pattern plate to the mounting frame. After the pattern plate has been secured to the mounting frame, the aligning portion can be detached from the pattern plate. The alignment pins can be reused at a later time. In some embodiments, the pattern plate can later be removed from the mounting frame, so that the mounting frame may be reused.

  6. HBT Interferometry: Historical Perspective

    CERN Document Server

    Padula, S S


    I review the history of HBT interferometry, since its discovery in the mid 50's, up to the recent developments and results from BNL/RHIC experiments. I focus the discussion on the contributions to the subject given by members of our Brazilian group.

  7. Mask Phenomenon in Communication

    Institute of Scientific and Technical Information of China (English)



    People sometimes wear masks. Abusive expression may be used to convey love while polite words can be exchanged among enemies. This essay describes and discusses this special phenomenon in communication and analyzes the elements that con-tribute to the success of a mask communication.

  8. Defect printability in CPL mask technology (United States)

    Kuijten, Jan-Pieter; Verhappen, Arjan; Pijnenburg, Wil; Conley, Will; Litt, Lloyd C.; Wu, Wei; Montgomery, Patrick; Roman, Bernard J.; Kasprowicz, Bryan S.; Progler, Christopher J.; Socha, Robert J.; Van Den Broeke, Douglas J.; Schaefer, Erika; Cook, Pat


    Each generation of semiconductor device technology drive new and interesting resolution enhancement technology (RET"s). The race to smaller and smaller geometry"s has forced device manufacturers to k1"s approaching 0.40. The authors have been investigating the use of Chromeless phase-shifting masks (CPL) exposed with ArF, high numerical aperture (NA), and off-axis illumination (OAI) has been shown to produce production worthy sub-100nm resist patterns with acceptable overlapped process window across feature pitch. These new reticle technologies have many issues that are similar to simple binary masks. The authors have investigated the printability of defects in CPL mask technology. Programmed defects of various sizes and types have been simulated and printed for sub 100nm imaging. High resolution scanning electron microscopy has been used to characterize these defects and develop an understanding of size and type that prints. In this paper the authors will focus on image line end shortening and the impact of through dose and focus performance for very high NA ArF imaging. The authors have built a number of test structures that require superior 2D control for SRAM gate structures. Various types of line ends have been evaluated for either straight CPL mask or hybrid type builds.

  9. Astronomical optical interferometry, II: Astrophysical results

    Directory of Open Access Journals (Sweden)

    Jankov S.


    Full Text Available Optical interferometry is entering a new age with several ground- based long-baseline observatories now making observations of unprecedented spatial resolution. Based on a great leap forward in the quality and quantity of interferometric data, the astrophysical applications are not limited anymore to classical subjects, such as determination of fundamental properties of stars; namely, their effective temperatures, radii, luminosities and masses, but the present rapid development in this field allowed to move to a situation where optical interferometry is a general tool in studies of many astrophysical phenomena. Particularly, the advent of long-baseline interferometers making use of very large pupils has opened the way to faint objects science and first results on extragalactic objects have made it a reality. The first decade of XXI century is also remarkable for aperture synthesis in the visual and near-infrared wavelength regimes, which provided image reconstructions from stellar surfaces to Active Galactic Nuclei. Here I review the numerous astrophysical results obtained up to date, except for binary and multiple stars milliarcsecond astrometry, which should be a subject of an independent detailed review, taking into account its importance and expected results at microarcsecond precision level. To the results obtained with currently available interferometers, I associate the adopted instrumental settings in order to provide a guide for potential users concerning the appropriate instruments which can be used to obtain the desired astrophysical information.

  10. Research on lithography based on the digital coding-mask technique (United States)

    Xu, Yanqiang; Luo, Ningning; Zhang, Zhimin; Bai, Lu; Gao, Yiqing


    Digital coding-mask technique based on digital micro-mirror devices (DMD) is proposed in this paper. The fundamental rule of digital coding-mask technique is to modulate the incident light intensity by adjusting the transmittance of the units on the coding-mask. The transmittance is controlled by the apertures on the units of the coding-mask. Lohmann's III coding method and error diffusion coding method are employed to coding mask, and wavelet transformation is used to suppress the background noise of the mask image. Real-time control on the image of the digital coding mask can be realized by loading the coded mask image to DMD, which is driven by a computer. Digital coding-mask technique gives full play of the advantages of DMD, such as real time and flexibility. In addition, the digital coding-mask technique is helpful to deal with the problem of mask aberration, which is caused by the nonlinear effect in the process of projection and exposure. This technique can also make use of optimization algorithm to suppress the background noise of the digital coding-mask images so that the quality of the relief structure of photoresist is improved.

  11. APT: Aperture Photometry Tool (United States)

    Laher, Russ


    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It has a graphical user interface (GUI) which allows the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. Mouse-clicking on a source in the displayed image draws a circular or elliptical aperture and sky annulus around the source and computes the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs, including image histogram, and aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has functions for customizing calculations, including outlier rejection, pixel “picking” and “zapping,” and a selection of source and sky models. The radial-profile-interpolation source model, accessed via the radial-profile-plot panel, allows recovery of source intensity from pixels with missing data and can be especially beneficial in crowded fields.

  12. Iterative supervirtual refraction interferometry

    KAUST Repository

    Al-Hagan, Ola


    In refraction tomography, the low signal-to-noise ratio (S/N) can be a major obstacle in picking the first-break arrivals at the far-offset receivers. To increase the S/N, we evaluated iterative supervirtual refraction interferometry (ISVI), which is an extension of the supervirtual refraction interferometry method. In this method, supervirtual traces are computed and then iteratively reused to generate supervirtual traces with a higher S/N. Our empirical results with both synthetic and field data revealed that ISVI can significantly boost up the S/N of far-offset traces. The drawback is that using refraction events from more than one refractor can introduce unacceptable artifacts into the final traveltime versus offset curve. This problem can be avoided by careful windowing of refraction events.

  13. Detailed IR aperture measurements

    CERN Document Server

    Bruce, Roderik; Garcia Morales, Hector; Giovannozzi, Massimo; Hermes, Pascal Dominik; Mirarchi, Daniele; Quaranta, Elena; Redaelli, Stefano; Rossi, Carlo; Skowronski, Piotr Krzysztof; Wretborn, Sven Joel; CERN. Geneva. ATS Department


    MD 1673 was carried out on October 5 2016, in order to investigate in more detail the available aperture in the LHC high-luminosity insertions at 6.5 TeV and β∗=40 cm. Previous aperture measurements in 2016 during commissioning had shown that the available aperture is at the edge of protection, and that the aperture bottleneck at β∗=40 cm in certain cases is found in the separation plane instead of in the crossing plane. Furthermore, the bottlenecks were consistently found in close to the upstream end of Q3 on the side of the incoming beam, and not in Q2 on the outgoing beam as expected from calculations. Therefore, this MD aimed at measuring IR1 and IR5 separately (at 6.5 TeV and β∗=40 cm, for 185 µrad half crossing angle), to further localize the bottlenecks longitudinally using newly installed BLMs, investigate the difference in aperture between Q2 and Q3, and to see if any aperture can be gained using special orbit bumps.

  14. Geometric Time Delay Interferometry


    Vallisneri, Michele


    The space-based gravitational-wave observatory LISA, a NASA-ESA mission to be launched after 2012, will achieve its optimal sensitivity using Time Delay Interferometry (TDI), a LISA-specific technique needed to cancel the otherwise overwhelming laser noise in the inter-spacecraft phase measurements. The TDI observables of the Michelson and Sagnac types have been interpreted physically as the virtual measurements of a synthesized interferometer. In this paper, I present Geometric TDI, a new an...

  15. Gilded Silver Mask

    Institute of Scientific and Technical Information of China (English)


    This gilded silver mask from the Liao Dynasty is 31 cm long and 22.2 cm wide. The plump oval face was designed with a protruding brow ridge, narrow eyes, high-bridged nose and closed mouth. The chin is slightly round against a thin neck, the ears are long and the hair can be clearly seen from the finely carved lines. The use of masks was recorded as

  16. Binary Masking & Speech Intelligibility

    DEFF Research Database (Denmark)

    Boldt, Jesper

    The purpose of this thesis is to examine how binary masking can be used to increase intelligibility in situations where hearing impaired listeners have difficulties understanding what is being said. The major part of the experiments carried out in this thesis can be categorized as either experime...... mask using a directional system and a method for correcting errors in the target binary mask. The last part of the thesis, proposes a new method for objective evaluation of speech intelligibility.......The purpose of this thesis is to examine how binary masking can be used to increase intelligibility in situations where hearing impaired listeners have difficulties understanding what is being said. The major part of the experiments carried out in this thesis can be categorized as either...... experiments under ideal conditions or as experiments under more realistic conditions useful for real-life applications such as hearing aids. In the experiments under ideal conditions, the previously defined ideal binary mask is evaluated using hearing impaired listeners, and a novel binary mask -- the target...

  17. New mask technology challenges (United States)

    Kimmel, Kurt R.


    Mask technology development has accelerated dramatically in recent years from the glacial pace of the last three decades to the rapid and sometimes simultaneous introductions of new wavelengths and mask-based resolution enhancement techniques. The nature of the semiconductor business has also become one driven by time-to-market as an overwhelming factor in capturing market share and profit. These are among the factors that have created enormous stress on the mask industry to produce masks with enhanced capabilities, such as phase-shifting attenuators, sub-resolution assist bars, and optical proximity correction (OPC) features, while maintaining or reducing cost and cycle time. The mask can no longer be considered a commodity item that is purchased form the lowest-cost supplier. Instead, it must now be promoted as an integral part of the technical and business case for a total lithographic solution. Improving partnership between designer, mask-maker, and wafer lithographer will be the harbinger of success in finding a profitable balance of capability, cost, and cycle time. Likewise for equipment infrastructure development, stronger partnership on the international level is necessary to control development cost and mitigate schedule and technical risks.

  18. Integrated optics for astronomical interferometry; 1, Concept and astronomical applications

    CERN Document Server

    Malbet, M; Schanen-Duport, J P; Berger, J P; Rousselet-Perraut, K; Benech, P


    We propose a new instrumental concept for long-baseline optical single-mode interferometry using integrated optics which were developed for telecommunication. Visible and infrared multi-aperture interferometry requires many optical functions (spatial filtering, beam combination, photometric calibration, polarization control) to detect astronomical signals at very high angular resolution. Since the 80's, integrated optics on planar substrate have become available for telecommunication applications with multiple optical functions like power dividing, coupling, multiplexing, etc. We present the concept of an optical / infrared interferometric instrument based on this new technology. The main advantage is to provide an interferometric combination unit on a single optical chip. Integrated optics are compact, provide stability, low sensitivity to external constrains like temperature, pressure or mechanical stresses, no optical alignment except for coupling, simplicity and intrinsic polarization control. The integra...

  19. Evaluation of coded aperture radiation detectors using a Bayesian approach (United States)

    Miller, Kyle; Huggins, Peter; Labov, Simon; Nelson, Karl; Dubrawski, Artur


    We investigate tradeoffs arising from the use of coded aperture gamma-ray spectrometry to detect and localize sources of harmful radiation in the presence of noisy background. Using an example application scenario of area monitoring and search, we empirically evaluate weakly supervised spectral, spatial, and hybrid spatio-spectral algorithms for scoring individual observations, and two alternative methods of fusing evidence obtained from multiple observations. Results of our experiments confirm the intuition that directional information provided by spectrometers masked with coded aperture enables gains in source localization accuracy, but at the expense of reduced probability of detection. Losses in detection performance can however be to a substantial extent reclaimed by using our new spatial and spatio-spectral scoring methods which rely on realistic assumptions regarding masking and its impact on measured photon distributions.

  20. Fast-neutron, coded-aperture imager

    Energy Technology Data Exchange (ETDEWEB)

    Woolf, Richard S., E-mail:; Phlips, Bernard F., E-mail:; Hutcheson, Anthony L., E-mail:; Wulf, Eric A., E-mail:


    This work discusses a large-scale, coded-aperture imager for fast neutrons, building off a proof-of concept instrument developed at the U.S. Naval Research Laboratory (NRL). The Space Science Division at the NRL has a heritage of developing large-scale, mobile systems, using coded-aperture imaging, for long-range γ-ray detection and localization. The fast-neutron, coded-aperture imaging instrument, designed for a mobile unit (20 ft. ISO container), consists of a 32-element array of 15 cm×15 cm×15 cm liquid scintillation detectors (EJ-309) mounted behind a 12×12 pseudorandom coded aperture. The elements of the aperture are composed of 15 cm×15 cm×10 cm blocks of high-density polyethylene (HDPE). The arrangement of the aperture elements produces a shadow pattern on the detector array behind the mask. By measuring of the number of neutron counts per masked and unmasked detector, and with knowledge of the mask pattern, a source image can be deconvolved to obtain a 2-d location. The number of neutrons per detector was obtained by processing the fast signal from each PMT in flash digitizing electronics. Digital pulse shape discrimination (PSD) was performed to filter out the fast-neutron signal from the γ background. The prototype instrument was tested at an indoor facility at the NRL with a 1.8-μCi and 13-μCi 252Cf neutron/γ source at three standoff distances of 9, 15 and 26 m (maximum allowed in the facility) over a 15-min integration time. The imaging and detection capabilities of the instrument were tested by moving the source in half- and one-pixel increments across the image plane. We show a representative sample of the results obtained at one-pixel increments for a standoff distance of 9 m. The 1.8-μCi source was not detected at the 26-m standoff. In order to increase the sensitivity of the instrument, we reduced the fastneutron background by shielding the top, sides and back of the detector array with 10-cm-thick HDPE. This shielding configuration led

  1. Mask Blank Defect Detection

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, M A; Sommargren, G E


    Mask blanks are the substrates that hold the master patterns for integrated circuits. Integrated circuits are semiconductor devices, such as microprocessors (mPs), dynamic random access memory (DRAMs), and application specific integrated circuits (ASICs) that are central to the computer, communication, and electronics industries. These devices are fabricated using a set of master patterns that are sequentially imaged onto light-sensitive coated silicon wafers and processed to form thin layers of insulating and conductive materials on top of the wafer. These materials form electrical paths and transistors that control the flow of electricity through the device. For the past forty years the semiconductor industry has made phenomenal improvements in device functionality, compactness, speed, power, and cost. This progress is principally due to the exponential decrease in the minimum feature size of integrated circuits, which has been reduced by a factor of {radical}2 every three years. Since 1992 the Semiconductor Industry Association (SIA) has coordinated the efforts of producing a technology roadmap for semiconductors. In the latest document, ''The International Technology Roadmap for Semiconductors: 1999'', future technology nodes (minimum feature sizes) and targeted dates were specified and are summarized in Table 1. Lithography is the imaging technology for producing a de-magnified image of the mask on the wafer. A typical de-magnification factor is 4. Mask blank defects as small as one-eighth the equivalent minimum feature size are printable and may cause device failure. Defects might be the result of the surface preparation, such as polishing, or contamination due to handling or the environment. Table 2 shows the maximum tolerable defect sizes on the mask blank for each technology node. This downward trend puts a tremendous burden on mask fabrication, particularly in the area of defect detection and reduction. A new infrastructure for mask

  2. Antihydrogen Experiment Gravity Interferometry Spectroscopy

    CERN Multimedia

    Gerber, S; Tietje, I C; Allkofer, Y R; Trezzi, D; Dassa, L; Rienacker, B; Khalidova, O; Ferrari, G; Krasnicky, D; Perini, D; Cerchiari, G; Belov, A; Boscolo, I; Sacerdoti, M G; Ferragut, R O; Nedelec, P; Testera, G; Hinterberger, A; Al-qaradawi, I; Malbrunot, C L S; Brusa, R S; Prelz, F; Manuzio, G; Riccardi, C; Fontana, A; Genova, P; Haider, S; Haug, F; Merkt, F; Turbabin, A; Castelli, F; Lagomarsino, V E; Doser, M; Penasa, L; Gninenko, S; Cataneo, F; Zenoni, A; Cabaret, L; Comparat, D P; Zmeskal, J; Scampoli, P; Dudarev, A; Kellerbauer, A G; Mariazzi, S; Fesel, J V; Nesteruk, K P; Carraro, C; Zavatarelli, S M

    The AEGIS experiment (Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy) has the aim of carrying out the first measurement of the gravitational interaction of antimatter to a precision of 1%, by applying techniques from atomic physics, laser spectroscopy and interferometry to a beam of antihydrogen atoms. A further goal of the experiment is to carry out spectroscopy of the antihydrogen atoms in flight.

  3. White Light Heterodyne Interferometry SNR (United States)


    for Research and Engineering under Air Force Contract FA8721-05-C-0002. Approved for public release; distribution is unlimited. White Light ...White Light Heterodyne Interferometry SNR J.B. Ashcom Group 91...public release; distribution is unlimited. ii ABSTRACT White light heterodyne interferometry is a powerful technique for obtaining high-angular

  4. Overview of Mask Metrology (United States)

    Rice, Bryan J.; Jindal, Vibhu; Lin, C. C.; Harris-Jones, Jenah; Kwon, Hyuk Joo; Ma, Hsing-Chien; Goldstein, Michael; Chan, Yau-Wai; Goodwin, Frank


    Extreme ultraviolet (EUV) lithography is the successor to optical lithography and will enable advanced patterning in semiconductor manufacturing processes down to the 8 nm half pitch technology node and beyond. However, before EUV can successfully be inserted into high volume manufacturing a few challenges must be overcome. Central among these remaining challenges is the requirement to produce "defect free" EUV masks. Mask blank defects have been one of the top challenges in the commercialization of extreme ultraviolet (EUV) lithography. To determine defect sources and devise mitigation solutions, detailed characterization of defects is critical. However, small defects pose challenges in metrology scale-up. SEMATECH has a comprehensive metrology strategy to address any defect larger than a 20 nm core size to obtain solutions for defect-free EUV mask blanks. SEMATECH's Mask Blank Development Center has been working since 2003 to develop the technology to support defect free EUV mask blanks. Since 2003, EUV mask blank defects have been reduced from 10000 of size greater than 100 nm to about a few tens at size 70 nm. Unfortunately, today's state of the art defect levels are still about 10 to 100 times higher than needed. Closing this gap requires progress in the various processes associated with glass substrate creation and multilayer deposition. That process development improvement in turn relies upon the availability of metrology equipment that can resolve and chemically characterize defects as small as 30 nm. The current defect reduction efforts at SEMATECH have intensively included a focus on inspection and characterization. The facility boasts nearly 100M of metrology hardware, including an FEI Titan TEM, Lasertec M1350 and M7360 tools, an actinic inspection tool, AFM, SPM, and scanning auger capabilities. The newly established Auger tool at SEMATECH can run a standard 6-inch mask blank and is already providing important information on sub-100 nm defects on EUV

  5. Confocal coded aperture imaging

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, Jr., Kenneth William (Harriman, TN); Thomas, Jr., Clarence E. (Knoxville, TN)


    A method for imaging a target volume comprises the steps of: radiating a small bandwidth of energy toward the target volume; focusing the small bandwidth of energy into a beam; moving the target volume through a plurality of positions within the focused beam; collecting a beam of energy scattered from the target volume with a non-diffractive confocal coded aperture; generating a shadow image of said aperture from every point source of radiation in the target volume; and, reconstructing the shadow image into a 3-dimensional image of the every point source by mathematically correlating the shadow image with a digital or analog version of the coded aperture. The method can comprise the step of collecting the beam of energy scattered from the target volume with a Fresnel zone plate.

  6. [The laryngeal mask]. (United States)

    Poltroniéri, J


    A new type of airway has been widely used for two years, throughout hospitals in the United Kingdom. Designed and created since 1983 by Dr AIJ Brain, the Laryngeal Mask Airway (LMA) is a compromise between the endotracheal tube and the face-mask. Blindly inserted in an anaesthetized patient, without either a laryngoscope or neuromuscular blockade, it provides a good airway in almost all cases. It is often able to offer an effective alternative to difficult intubation. The LMA can be used with either spontaneous or positive pressure ventilation. Because it doesn't provide a reliable protection of the airway from aspiration, it should never be used in the patient with a full stomach. The spontaneously breathing patient, undergoing elective surgery for 15 to 60 minutes, in supine position, who would ordinarily be managed with a face-mask is the more likely candidate for the LMA. But, longer procedures, in lateral or prone position, with controlled ventilation can usually be carried out using the Brain's device. More effective and less demanding than the facial-mask, much less hurtful than the endotracheal tube, the Laryngeal Mask is potentially an important and valuable addition to anaesthetic care.

  7. Orion Emergency Mask Approach (United States)

    Tuan, George C.; Graf, John C.


    Emergency mask approach on Orion poses a challenge to the traditional Shuttle or Station approaches. Currently, in the case of a fire or toxic spill event, the crew utilizes open loop oxygen masks that provide the crew with oxygen to breath, but also dumps the exhaled oxygen into the cabin. For Orion, with a small cabin volume, the extra oxygen will exceed the flammability limit within a short period of time, unless a nitrogen purge is also provided. Another approach to a fire or toxic spill event is the use of a filtering emergency masks. These masks utilize some form of chemical beds to scrub the air clean of toxic providing the crew safe breathing air for a period without elevating the oxygen level in the cabin. Using the masks and a form of smoke-eater filter, it may be possible to clean the cabin completely or to a level for safe transition to a space suit to perform a cabin purge. Issues with filters in the past have been the reaction time, breakthroughs, and high breathing resistance. Development in a new form of chemical filters has shown promise to make the filtering approach feasible.

  8. High Performance Lyot and PIAA Coronagraphy for Arbitrarily shaped Telescope Apertures

    CERN Document Server

    Guyon, Olivier; Cady, Eric; Belikov, Ruslan; Martinache, Frantz


    Two high performance coronagraphic approaches compatible with segmented and obstructed telescope pupils are described. Both concepts use entrance pupil amplitude apodization and a combined phase and amplitude focal plane mask to achieve full coronagraphic extinction of an on-axis point source. While the first concept, named Apodized Pupil Complex Mask Lyot Coronagraph (APCMLC), relies on a transmission mask to perform the pupil apodization, the second concept, named Phase-Induced Amplitude Apodization complex mask coronagraph (PIAACMC), uses beam remapping for lossless apodization. Both concepts theoretically offer complete coronagraphic extinction (infinite contrast) of a point source in monochromatic light, with high throughput and sub-lambda/D inner working angle, regardless of aperture shape. The PIAACMC offers nearly 100% throughput and approaches the fundamental coronagraph performance limit imposed by first principles. The steps toward designing the coronagraphs for arbitrary apertures are described fo...

  9. Aperture Photometry Tool (United States)

    Laher, Russ R.; Gorjian, Varoujan; Rebull, Luisa M.; Masci, Frank J.; Fowler, John W.; Helou, George; Kulkarni, Shrinivas R.; Law, Nicholas M.


    Aperture Photometry Tool (APT) is software for astronomers and students interested in manually exploring the photometric qualities of astronomical images. It is a graphical user interface (GUI) designed to allow the image data associated with aperture photometry calculations for point and extended sources to be visualized and, therefore, more effectively analyzed. The finely tuned layout of the GUI, along with judicious use of color-coding and alerting, is intended to give maximal user utility and convenience. Simply mouse-clicking on a source in the displayed image will instantly draw a circular or elliptical aperture and sky annulus around the source and will compute the source intensity and its uncertainty, along with several commonly used measures of the local sky background and its variability. The results are displayed and can be optionally saved to an aperture-photometry-table file and plotted on graphs in various ways using functions available in the software. APT is geared toward processing sources in a small number of images and is not suitable for bulk processing a large number of images, unlike other aperture photometry packages (e.g., SExtractor). However, APT does have a convenient source-list tool that enables calculations for a large number of detections in a given image. The source-list tool can be run either in automatic mode to generate an aperture photometry table quickly or in manual mode to permit inspection and adjustment of the calculation for each individual detection. APT displays a variety of useful graphs with just the push of a button, including image histogram, x and y aperture slices, source scatter plot, sky scatter plot, sky histogram, radial profile, curve of growth, and aperture-photometry-table scatter plots and histograms. APT has many functions for customizing the calculations, including outlier rejection, pixel "picking" and "zapping," and a selection of source and sky models. The radial-profile-interpolation source model

  10. Monitoring Crustal Deformations with Radar Interferometry:A Review

    Institute of Scientific and Technical Information of China (English)

    刘国祥; 丁晓利; 黄丁发


    The crustal movements, probably motivating earthquakes, are considered as one of the main geodynamic sources. The quantitative measurements of ground surface deformations are vital for studying mechanisms of the buried faults or even estimating earthquake potential. A new space-geodetic technology, synthetic aperture radar interferometry (InSAR), can be applied to detect such large-area deformations, and has demonstrated some prominent advantages. This paper reviews the capacity and limitations of InSAR, and summarises the existing applications including some of our results in studying the earthquake-related crustal motions.Finally it gives the outlook for the future development of InSAR.

  11. Basics of interferometry

    CERN Document Server

    Hariharan, P


    This book is for those who have some knowledge of optics, but little or no previous experience in interferometry. Accordingly, the carefully designed presentation helps readers easily find and assimilate the interferometric techniques they need for precision measurements. Mathematics is held to a minimum, and the topics covered are also summarized in capsule overviews at the beginning and end of each chapter. Each chapter also contains a set of worked problems that give a feel for numbers.The first five chapters present a clear tutorial review of fundamentals. Chapters six and seven discus

  12. Utilization of InSAR differential interferometry for surface deformation detection caused by mining

    Energy Technology Data Exchange (ETDEWEB)

    Yang, F. [Liaoning Technical Univ., Fuxin (China). School of Geomatics; Shao, Y. [Liaoning Technical Univ., Fuxin (China). Dept. of Foreign Language; Guichen, M. [Gifu Univ., Yanagido, Gifu (Japan). Dept. of Civil Engineering


    In China, the surface deformation of ground has been a significant geotechnical problem as a result of cracks in the ground surface, collapsing of house, and subsidence of roads. A powerful technology for detecting surface deformation in the ground is differential interferometry using synthetic aperture radar (INSAR). The technology enables the analysis from different phase of micro-wave between two observed data by synthetic aperture radar (SAR) of surface deformation of ground such as ground subsidence, land slide, and slope failure. In January 2006, the advanced land observing satellite was launched by the Japan Aerospace Exploration Agency. This paper presented an analytical investigation to detect ground subsidence or change caused by mining, overuse of ground water, and disaster. Specifically, the paper discussed the INSAR monitoring technology of the mine slope, including INSAR data sources and processing software; the principle of synthetic aperture radar interferometry; principles of differential SAR interferometry; and INSAR technology to slope monitoring of the Haizhou open pit mine. The paper also discussed the Haizhou strip mine side slope INSAR monitoring results and tests. It was concluded that the use of synthetic aperture radar interferometer technique was the optimal technique to provide three-dimensional spatial information and minimal change from ground surface by spatial remote sensing device. 18 refs., 5 figs.

  13. Label-free single molecule imaging with numerical aperture-shaped interferometric scattering microscopy

    CERN Document Server

    Cole, Daniel; Weigel, Alexander; Kukura, P


    Our ability to optically interrogate nanoscopic objects is controlled by the difference between their extinction cross sections and the diffraction limited area to which light can be confined in the far field. We show that a partially transmissive spatial mask placed near the back focal plane of a high numerical aperture microscope objective enhances the extinction contrast of a scatterer near an interface by approximately $T^{-1/2}$, where T is the transmissivity of the mask. Numerical aperture based differentiation of background from scattered light represents a general approach to increasing extinction contrast and enables routine label free imaging down to the single molecule level.

  14. An Aperture Photometry Pipeline for K2 Data (United States)

    Buzasi, Derek L.; Carboneau, Lindsey; Lezcano, Andy; Vydra, Ekaterina


    As part of an ongoing research program with undergraduate students at Florida Gulf Coast University, we have constructed an aperture photometry pipeline for K2 data. The pipeline performs dynamic automated aperture mask definition for all targets in the K2 fields, followed by aperture photometry and detrending. Our pipeline is currently used to support a number of projects, including studies of stellar rotation and activity, red giant asteroseismology, gyrochronology, and exoplanet searches. In addition, output is used to support an undergraduate class on exoplanets aimed at a student audience of both majors and non-majors. The pipeline is designed for both batch and single-target use, and is easily extensible to data from other missions, and pipeline output is available to the community. This paper will describe our pipeline and its capabilities and illustrate the quality of the results, drawing on all of the applications for which it is currently used.

  15. Time-Delay Interferometry

    Directory of Open Access Journals (Sweden)

    Massimo Tinto


    Full Text Available Equal-arm detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is differenced at the photo detector. In this situation, much lower level secondary noises then set the overall performance. If, however, the two arms have different lengths (as will necessarily be the case with space-borne interferometers, the laser noise experiences different delays in the two arms and will hence not directly cancel at the detector. In order to solve this problem, a technique involving heterodyne interferometry with unequal arm lengths and independent phase-difference readouts has been proposed. It relies on properly time-shifting and linearly combining independent Doppler measurements, and for this reason it has been called time-delay interferometry (TDI. This article provides an overview of the theory, mathematical foundations, and experimental aspects associated with the implementation of TDI. Although emphasis on the application of TDI to the Laser Interferometer Space Antenna (LISA mission appears throughout this article, TDI can be incorporated into the design of any future space-based mission aiming to search for gravitational waves via interferometric measurements. We have purposely left out all theoretical aspects that data analysts will need to account for when analyzing the TDI data combinations.

  16. RHIC prefire protection masks

    Energy Technology Data Exchange (ETDEWEB)

    Drees, A.; Biscardi, C.; Curcio, T.; Gassner, D.; DeSanto, L.; Fu, W.; Liaw, C. J.; Montag, C.; Thieberger, P.; Yip, K.


    The protection of the RHIC experimental detectors from damage due to beam hitting close upstream elements in cases of abort kicker prefires requires some dedicated precautionary measures with two general options: to bring the beam close to a limiting aperture (i.e. the beam pipe wall), as far upstream of the detector components as possible or, alternatively, to bring a limiting aperture close to the circulating beam. Spontaneous and random prefires of abort kicker modules (Pulse Forming Network, PFN) have a history as long as RHIC is being operated. The abort system consist of 5 kickers in per ring, each of them equipped with its own dedicated PFN.

  17. Variable optofluidic slit aperture

    Institute of Scientific and Technical Information of China (English)

    Stefan Schuhladen; Kaustubh Banerjee; Moritz Stürmer; Philipp Müller; Ulrike Wallrabe; Hans Zappe


    The shape of liquid interfaces can be precisely controlled using electrowetting,an actuation mechanism which has been widely used for tunable optofluidic micro-optical components such as lenses or irises.We have expanded the considerable flexibility inherent in electrowetting actuation to realize a variable optofluidic slit,a tunable and reconfigurable two-dimensional aperture with no mechanically moving parts.This optofluidic slit is formed by precisely controlled movement of the liquid interfaces of two highly opaque ink droplets.The 1.5 mm long slit aperture,with controllably variable discrete widths down to 45 μm,may be scanned across a length of 1.5 mm with switching times between adjacent slit positions of less than 120 ms.In addition,for a fixed slit aperture position,the width may be tuned to a minimum of 3 μm with high uniformity and linearity over the entire slit length.This compact,purely fluidic device offers an electrically controlled aperture tuning range not achievable with extant mechanical alternatives of a similar size.

  18. 3D Marine CSEM Interferometry by Multidimensional Deconvolution in the Wavenumber Domain for a Sparse Receiver Grid

    NARCIS (Netherlands)

    Hunziker, J.W.; Slob, E.C.; Fan, Y.; Snieder, R.; Wapenaar, C.P.A.


    We use interferometry by multidimensional deconvolution in combination with synthetic aperture sources in 3D to suppress the airwave and the direct field, and to decrease source uncertainty in marine Controlled-Source electromagnetics. We show with this numerical study that the method works for very

  19. COAs: Behind the Masks. (United States)

    Birke, Szifra


    Provides information on alcoholism and codependency to help teachers identify and respond to children of alcoholics (COAs). Discusses characteristics of alcoholic homes and problems encountered by children and adult COAs. Examines survival "masks" of COAs, including hero, rebel, adjustor, clown, and caretaker. Lists organizational,…

  20. Masked mycotoxins: a review. (United States)

    Berthiller, Franz; Crews, Colin; Dall'Asta, Chiara; Saeger, Sarah De; Haesaert, Geert; Karlovsky, Petr; Oswald, Isabelle P; Seefelder, Walburga; Speijers, Gerrit; Stroka, Joerg


    The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non-extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders.

  1. CADAT integrated circuit mask analysis (United States)


    CADAT System Mask Analysis Program (MAPS2) is automated software tool for analyzing integrated-circuit mask design. Included in MAPS2 functions are artwork verification, device identification, nodal analysis, capacitance calculation, and logic equation generation.

  2. Bubble masks for time-encoded imaging of fast neutrons.

    Energy Technology Data Exchange (ETDEWEB)

    Brubaker, Erik; Brennan, James S.; Marleau, Peter; Nowack, Aaron B.; Steele, John T.; Sweany, Melinda; Throckmorton, Daniel J.


    Time-encoded imaging is an approach to directional radiation detection that is being developed at SNL with a focus on fast neutron directional detection. In this technique, a time modulation of a detected neutron signal is inducedtypically, a moving mask that attenuates neutrons with a time structure that depends on the source position. An important challenge in time-encoded imaging is to develop high-resolution two-dimensional imaging capabilities; building a mechanically moving high-resolution mask presents challenges both theoretical and technical. We have investigated an alternative to mechanical masks that replaces the solid mask with a liquid such as mineral oil. Instead of fixed blocks of solid material that move in pre-defined patterns, the oil is contained in tubing structures, and carefully introduced air gapsbubblespropagate through the tubing, generating moving patterns of oil mask elements and air apertures. Compared to current moving-mask techniques, the bubble mask is simple, since mechanical motion is replaced by gravity-driven bubble propagation; it is flexible, since arbitrary bubble patterns can be generated by a software-controlled valve actuator; and it is potentially high performance, since the tubing and bubble size can be tuned for high-resolution imaging requirements. We have built and tested various single-tube mask elements, and will present results on bubble introduction and propagation as a function of tubing size and cross-sectional shape; real-time bubble position tracking; neutron source imaging tests; and reconstruction techniques demonstrated on simple test data as well as a simulated full detector system.

  3. Decoherence Free Neutron Interferometry

    CERN Document Server

    Pushin, Dmitry A; Cory, David G


    Perfect single-crystal neutron interferometers are adversely sensitive to environmental disturbances, particularly mechanical vibrations. The sensitivity to vibrations results from the slow velocity of thermal neutrons and the long measurement time that are encountered in a typical experiment. Consequently, to achieve a good interference solutions for reducing vibration other than those normally used in optical experiments must be explored. Here we introduce a geometry for a neutron interferometer that is less sensitive to low-frequency vibrations. This design may be compared with both dynamical decoupling methods and decoherence-free subspaces that are described in quantum information processing. By removing the need for bulky vibration isolation setups, this design will make it easier to adopt neutron interferometry to a wide range of applications and increase its sensitivity.

  4. Bandwidth in bolometric interferometry

    CERN Document Server

    Charlassier, R; Hamilton, J -Ch; Kaplan, J; Malu, S


    Bolometric Interferometry is a technology currently under development that will be first dedicated to the detection of B-mode polarization fluctuations in the Cosmic Microwave Background. A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers in order to be competitive with imaging experiments. A crucial concern is that interferometers are presumed to be importantly affected by a spoiling effect known as bandwidth smearing. In this paper, we investigate how the bandwidth modifies the work principle of a bolometric interferometer and how it affects its sensitivity to the CMB angular power spectra. We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. Using an angular power spectrum estimator ...

  5. Congenital pyriform aperture stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Osovsky, Micky [Schneider Pediatric Hospital, Department of Neonatology, Petach Tikvah (Israel); Rabin Medical Center, Department of Neonatology, Schneider Children' s Medical Center of Israel, Beilinson Campus, Petah Tikvah (Israel); Aizer-Danon, Anat; Horev, Gadi [Schneider Pediatric Hospital, Department of Pediatric Radiology, Petach Tikvah (Israel); Sirota, Lea [Schneider Pediatric Hospital, Department of Neonatology, Petach Tikvah (Israel)


    Nasal airway obstruction is a potentially life-threatening condition in the newborn. Neonates are obligatory nasal breathers. The pyriform aperture is the narrowest, most anterior bony portion of the nasal airway, and a decrease in its cross-sectional area will significantly increase nasal airway resistance. Congenital nasal pyriform aperture stenosis (CNPAS) is a rare, unusual form of nasal obstruction. It should be considered in the differential diagnosis of any neonate or infant with signs and symptoms of upper airway compromise. It is important to differentiate this level of obstruction from the more common posterior choanal stenosis or atresia. CNPAS presents with symptoms of nasal airway obstruction, which are often characterized by episodic apnea and cyclical cyanosis. (orig.)

  6. Far field 3D localization of radioactive hot spots using a coded aperture camera. (United States)

    Shifeng, Sun; Zhiming, Zhang; Lei, Shuai; Daowu, Li; Yingjie, Wang; Yantao, Liu; Xianchao, Huang; Haohui, Tang; Ting, Li; Pei, Chai; Yiwen, Zhang; Wei, Zhou; Mingjie, Yang; Cunfeng, Wei; Chuangxin, Ma; Long, Wei


    This paper presents a coded aperture method to remotely estimate the radioactivity of a source. The activity is estimated from the detected counts and the estimated source location, which is extracted by factoring the effect of aperture magnification. A 6mm thick tungsten-copper alloy coded aperture mask is used to modulate the incoming gamma-rays. The location of point and line sources in all three dimensions was estimated with an accuracy of less than 10% when the source-camera distance was about 4 m. The estimated activities were 17.6% smaller and 50.4% larger than the actual activities for the point and line sources, respectively.

  7. The VIRMOS mask manufacturing tools; 2, Mask manufacturing and handling

    CERN Document Server

    Conti, G; Mattaini, E; MacCagni, D; Lefèvre, O; Saisse, M; Vettolani, G


    We describe the VIRMOS Mask Manufacturing Unit (MMU) configuration, composed of two units:the Mask Manufacturing Machine (with its Control Unit) and the Mask Handling Unit (inclusive of Control Unit, Storage Cabinets and robot for loading of the Instrument Cabinets). For both VIMOS and NIRMOS instruments, on the basis of orders received by the Mask Preparation Software (see paper (a) in same proceedings), the function of the MMU is to perform an off-line mask cutting and identification, followed by mask storing and subsequent filling of the Instrument Cabinets (IC). We describe the characteristics of the LPKF laser cutting machine and the work done to support the choice of this equipment. We also describe the remaining of the hardware configuration and the Mask Handling Software.

  8. Non-null annular subaperture stitching interferometry for aspheric test (United States)

    Zhang, Lei; Liu, Dong; Shi, Tu; Yang, Yongying; Chong, Shiyao; Miao, Liang; Huang, Wei; Shen, Yibing; Bai, Jian


    A non-null annular subaperture stitching interferometry (NASSI), combining the subaperture stitching idea and non-null test method, is proposed for steep aspheric testing. Compared with standard annular subaperture stitching interferometry (ASSI), a partial null lens (PNL) is employed as an alternative to the transmission sphere, to generate different aspherical wavefronts as the references. The coverage subaperture number would thus be reduced greatly for the better performance of aspherical wavefronts in matching the local slope of aspheric surfaces. Instead of various mathematical stitching algorithms, a simultaneous reverse optimizing reconstruction (SROR) method based on system modeling and ray tracing is proposed for full aperture figure error reconstruction. All the subaperture measurements are simulated simultaneously with a multi-configuration model in a ray-tracing program, including the interferometric system modeling and subaperture misalignments modeling. With the multi-configuration model, full aperture figure error would be extracted in form of Zernike polynomials from subapertures wavefront data by the SROR method. This method concurrently accomplishes subaperture retrace error and misalignment correction, requiring neither complex mathematical algorithms nor subaperture overlaps. A numerical simulation exhibits the comparison of the performance of the NASSI and standard ASSI, which demonstrates the high accuracy of the NASSI in testing steep aspheric. Experimental results of NASSI are shown to be in good agreement with that of Zygo® VerifireTM Asphere interferometer.

  9. Preparations for EUV interferometry of the 0.3 NA MET optic

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, Kenneth A.; Naulleau, Patrick P.; Denham, Paul E.; Rekawa, Senajith B.; Jackson, Keith H.; Liddle, J. Alexander; Harteneck, Bruce; Gullikson, Eric; Anderson, Erik H.


    An at-wavelength interferometer is being created for the measurement and alignment of the 0.3 numerical aperture Micro Exposure Tool projection optic at EUV wavelengths. The prototype MET system promises to provide early learning from EUV lithographic imaging down to 20-nm feature size. The threefold increase to 0.3 NA in the image-side numerical aperture presents several challenges for the extension of ultra-high-accuracy interferometry, including pinhole fabrication and the calibration and removal of systematic error sources.

  10. Fabrication of complex oxide microstructures by combinatorial chemical beam vapour deposition through stencil masks

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, E. [3D-OXIDES, 70 rue Gustave Eiffel, Saint Genis Pouilly 01630 (France); Sandu, C.S., E-mail: [3D-OXIDES, 70 rue Gustave Eiffel, Saint Genis Pouilly 01630 (France); Laboratoire de Céramique, Ecole Polytechnique Fédérale de Lausanne, Station 12, CH-1015 Lausanne (Switzerland); Harada, S.; Benvenuti, G. [3D-OXIDES, 70 rue Gustave Eiffel, Saint Genis Pouilly 01630 (France); Savu, V. [Laboratoire de Microsystèmes 1, Ecole Polytechnique Fédérale de Lausanne, Station 17, CH-1015 Lausanne (Switzerland); Muralt, P. [Laboratoire de Céramique, Ecole Polytechnique Fédérale de Lausanne, Station 12, CH-1015 Lausanne (Switzerland)


    Chemical Beam Vapour Deposition is a gas phase deposition technique, operated under high vacuum conditions, in which evaporated chemical precursors are thermally decomposed on heated substrates to form a film. In the particular equipment used in this work, different chemical beams effuse from a plurality of punctual precursor sources with line of sight trajectory to the substrate. A shadow mask is used to produce 3D-structures in a single step, replicating the apertures of a stencil as deposits on the substrate. The small gap introduced between substrate and mask induces a temperature difference between both surfaces and is used to deposit selectively solely on the substrate without modifying the mask, taking advantage of the deposition rate dependency on temperature. This small gap also enables the deposition of complex patterned structures resulting from the superposition of many patterns obtained using several precursor beams from different directions through a single mask aperture. A suitable process parameter window for precursor flow and substrate temperature is evidenced to maximize resolution. - Highlights: • Micro-feature growth with stencil mask by Chemical Beam Vapour Deposition • Growth of complex structured oxide films in one step • The gap between substrate and mask avoids deposition on the stencil. • Fabrication of 3D structures by superposing deposits from several beams • The versatile setup combines few chemical beams, variable geometry and stencil mask patterns.

  11. Masked multichannel analyzer (United States)

    Winiecki, A.L.; Kroop, D.C.; McGee, M.K.; Lenkszus, F.R.


    An analytical instrument and particularly a time-of-flight-mass spectrometer for processing a large number of analog signals irregularly spaced over a spectrum, with programmable masking of portions of the spectrum where signals are unlikely in order to reduce memory requirements and/or with a signal capturing assembly having a plurality of signal capturing devices fewer in number than the analog signals for use in repeated cycles within the data processing time period.

  12. Mask strategy at International SEMATECH (United States)

    Kimmel, Kurt R.


    International SEMATECH (ISMT) is a consortium consisting of 13 leading semiconductor manufacturers from around the globe. Its objective is to develop the infrastructure necessary for its member companies to realize the International Technology Roadmap for Semiconductors (ITRS) through efficiencies of shared development resources and knowledge. The largest area of effort is lithography, recognized as a crucial enabler for microelectronics technology progress. Within the Lithography Division, most of the efforts center on mask-related issues. The development strategy at International SEMATCH will be presented and the interlock of lithography projects clarified. Because of the limited size of the mask production equipment market, the business case is weak for aggressive investment commensurate with the pace of the International Technology Roadmap for Semiconductors. With masks becoming the overwhelming component of lithography cost, new ways of reducing or eliminating mask costs are being explored. Will mask technology survive without a strong business case? Will the mask industry limit the growth of the semiconductor industry? Are advanced masks worth their escalating cost? An analysis of mask cost from the perspective of mask value imparted to the user is presented with examples and generic formulas for the reader to apply independently. A key part to the success for both International SEMATECH and the industry globally will be partnerships on both the local level between mask-maker and mask-user, and the macro level where global collaborations will be necessary to resolve technology development cost challenges.


    Directory of Open Access Journals (Sweden)



    Full Text Available Avian influenza (bird flu is a disease of birds caused by influenza viruses closely related to human influenza viruses. The potential for transformation of avian influenza into a form that both causes severe disease in humans and spreads easily from person to person is a great concern for world health. The main purpose of a mask is to help prevent particles (droplets being expelled into the environment by the wearer. Masks are also resistant to fluids, and help protect the wearer from splashes of blood or other potentially infectious substances. They are not necessarily designed for filtration efficiency, or to seal tightly to the face. Masks and respirators are components of a number of infection control measures intended to protect healthcare workers, and prevent the spread of diseases. All healthcare workers who come into contact with a possible or probable case of any respiratory track infections should wear a respirator conforming to at least EN149:2001 FFP3. [TAF Prev Med Bull 2006; 5(4.000: 296-306

  14. High Performance Lyot and PIAA Coronagraphy for Arbitrarily Shaped Telescope Apertures (United States)

    Guyon, Olivier; Hinz, Philip M.; Cady, Eric; Belikov, Ruslan; Martinache, Frantz


    Two high-performance coronagraphic approaches compatible with segmented and obstructed telescope pupils are described. Both concepts use entrance pupil amplitude apodization and a combined phase and amplitude focal plane mask to achieve full coronagraphic extinction of an on-axis point source. While the first concept, called Apodized Pupil Complex Mask Lyot Coronagraph (APCMLC), relies on a transmission mask to perform the pupil apodization, the second concept, called Phase-Induced Amplitude Apodization complex mask coronagraph (PIAACMC), uses beam remapping for lossless apodization. Both concepts theoretically offer complete coronagraphic extinction (infinite contrast) of a point source in monochromatic light, with high throughput and sub-λ/D inner working angle, regardless of aperture shape. The PIAACMC offers nearly 100% throughput and approaches the fundamental coronagraph performance limit imposed by first principles. The steps toward designing the coronagraphs for arbitrary apertures are described for monochromatic light. Designs for the APCMLC and the higher performance PIAACMC are shown for several monolith and segmented apertures, such as the apertures of the Subaru Telescope, Giant Magellan Telescope, Thirty Meter Telescope, the European Extremely Large Telescope, and the Large Binocular Telescope. Performance in broadband light is also quantified, suggesting that the monochromatic designs are suitable for use in up to 20% wide spectral bands for ground-based telescopes.

  15. High performance Lyot and PIAA coronagraphy for arbitrarily shaped telescope apertures

    Energy Technology Data Exchange (ETDEWEB)

    Guyon, Olivier; Hinz, Philip M. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Cady, Eric [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Belikov, Ruslan [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Martinache, Frantz, E-mail: [National Astronomical Observatory of Japan, Subaru Telescope, Hilo, HI 96720 (United States)


    Two high-performance coronagraphic approaches compatible with segmented and obstructed telescope pupils are described. Both concepts use entrance pupil amplitude apodization and a combined phase and amplitude focal plane mask to achieve full coronagraphic extinction of an on-axis point source. While the first concept, called Apodized Pupil Complex Mask Lyot Coronagraph (APCMLC), relies on a transmission mask to perform the pupil apodization, the second concept, called Phase-Induced Amplitude Apodization complex mask coronagraph (PIAACMC), uses beam remapping for lossless apodization. Both concepts theoretically offer complete coronagraphic extinction (infinite contrast) of a point source in monochromatic light, with high throughput and sub-λ/D inner working angle, regardless of aperture shape. The PIAACMC offers nearly 100% throughput and approaches the fundamental coronagraph performance limit imposed by first principles. The steps toward designing the coronagraphs for arbitrary apertures are described for monochromatic light. Designs for the APCMLC and the higher performance PIAACMC are shown for several monolith and segmented apertures, such as the apertures of the Subaru Telescope, Giant Magellan Telescope, Thirty Meter Telescope, the European Extremely Large Telescope, and the Large Binocular Telescope. Performance in broadband light is also quantified, suggesting that the monochromatic designs are suitable for use in up to 20% wide spectral bands for ground-based telescopes.

  16. Extreme ultraviolet interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, Kenneth A. [Univ. of California, Berkeley, CA (United States). Dept. of Physics


    EUV lithography is a promising and viable candidate for circuit fabrication with 0.1-micron critical dimension and smaller. In order to achieve diffraction-limited performance, all-reflective multilayer-coated lithographic imaging systems operating near 13-nm wavelength and 0.1 NA have system wavefront tolerances of 0.27 nm, or 0.02 waves RMS. Owing to the highly-sensitive resonant reflective properties of multilayer mirrors and extraordinarily tight tolerances set forth for their fabrication, EUV optical systems require at-wavelength EUV interferometry for final alignment and qualification. This dissertation discusses the development and successful implementation of high-accuracy EUV interferometric techniques. Proof-of-principle experiments with a prototype EUV point-diffraction interferometer for the measurement of Fresnel zoneplate lenses first demonstrated sub-wavelength EUV interferometric capability. These experiments spurred the development of the superior phase-shifting point-diffraction interferometer (PS/PDI), which has been implemented for the testing of an all-reflective lithographic-quality EUV optical system. Both systems rely on pinhole diffraction to produce spherical reference wavefronts in a common-path geometry. Extensive experiments demonstrate EUV wavefront-measuring precision beyond 0.02 waves RMS. EUV imaging experiments provide verification of the high-accuracy of the point-diffraction principle, and demonstrate the utility of the measurements in successfully predicting imaging performance. Complementary to the experimental research, several areas of theoretical investigation related to the novel PS/PDI system are presented. First-principles electromagnetic field simulations of pinhole diffraction are conducted to ascertain the upper limits of measurement accuracy and to guide selection of the pinhole diameter. Investigations of the relative merits of different PS/PDI configurations accompany a general study of the most significant sources

  17. Scanning coherent scattering methods for actinic EUV mask inspection (United States)

    Ekinci, Y.; Helfenstein, P.; Rajeev, R.; Mochi, I.; Mohacsi, I.; Gobrecht, J.; Yoshitake, S.


    Actinic mask inspection for EUV lithography with targeted specifications of resolution, sensitivity, and throughput remains a big hurdle for the successful insertion of EUVL into high volume manufacturing and effective solutions are needed to address this. We present a method for actinic mask inspection based on scanning coherent scattering microscopy. In this method, the mask is scanned with an EUV beam of relatively small spot size and the scattered light is recorded with a pixel detector. Customized algorithms reconstruct the aerial image by iteratively solving the phaseproblem using over-determined diffraction data gathered by scanning across the specimen with a finite illumination. This approach provides both phase and amplitude of actinic aerial images of the mask with high resolution without the need to use high NA (numerical aperture) lenses. Futher, we describe a reflective mode EUV mask scanning lensless imaging tool (RESCAN), which was installed at the XIL-II beamline and later at the SIM beamline of the Swiss Light Source and show reconstructed aerial images down to 10 nm (on-wafer) resolution. As a complementary method, the a-priori knowledge of the sample is employed to identify potential defect sites by analyzing the diffraction patterns. In this method, the recorded diffraction patterns are compared with the die or database data (i.e. previously measured or calculated diffraction data from the defect-free mask layout respectively) and their difference is interpreted as the defect signal. Dynamic software filtering helps to suppress the strong diffraction from defect-free structures and allows registration of faint defects with high sensitivity. Here, we discuss the basic principles of these Fourier domain techniques and its potential for actinic mask inspection with high signal-to-noise ratio and high throughput.

  18. Lyot coronagraph design study for large, segmented space telescope apertures (United States)

    Zimmerman, Neil T.; N'Diaye, Mamadou; St. Laurent, Kathryn E.; Soummer, Rémi; Pueyo, Laurent; Stark, Christopher C.; Sivaramakrishnan, Anand; Perrin, Marshall; Vanderbei, Robert J.; Kasdin, N. J.; Shaklan, Stuart; Carlotti, Alexis


    Recent efforts combining the optimization techniques of apodized pupil Lyot coronagraphs (APLC) and shaped pupils have demonstrated the viability of a binary-transmission mask architecture for extremely high contrast (10-10) exoplanet imaging. We are now building on those innovations to carry out a survey of Lyot coronagraph performance for large, segmented telescope apertures. These apertures are of the same kind under considera- tion for NASA's Large UV/Optical/IR (LUVOIR) observatory concept. To map the multi-dimensional design parameter space, we have developed a software toolkit to manage large sets of mask optimization programs and execute them on a computing cluster. Here we summarize a preliminary survey of 500 APLC solutions for 4 reference hexagonal telescope apertures. Several promising designs produce annular, 10-10 contrast dark zones down to inner working angle 4λ0=D over a 15% bandpass, while delivering a half-max PSF core throughput of 18%. We also report our progress on devising solutions to the challenges of Lyot stop alignment/fabrication tolerance that arise in this contrast regime.

  19. Mask alignment system for semiconductor processing

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Aaron P.; Carlson, Charles T.; Weaver, William T.; Grant, Christopher N.


    A mask alignment system for providing precise and repeatable alignment between ion implantation masks and workpieces. The system includes a mask frame having a plurality of ion implantation masks loosely connected thereto. The mask frame is provided with a plurality of frame alignment cavities, and each mask is provided with a plurality of mask alignment cavities. The system further includes a platen for holding workpieces. The platen may be provided with a plurality of mask alignment pins and frame alignment pins configured to engage the mask alignment cavities and frame alignment cavities, respectively. The mask frame can be lowered onto the platen, with the frame alignment cavities moving into registration with the frame alignment pins to provide rough alignment between the masks and workpieces. The mask alignment cavities are then moved into registration with the mask alignment pins, thereby shifting each individual mask into precise alignment with a respective workpiece.

  20. Landau-Zener-Stueckelberg interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Shevchenko, S.N., E-mail: sshevchenko@ilt.kharkov.u [B.Verkin Institute for Low Temperature Physics and Engineering, Kharkov (Ukraine); RIKEN Advanced Science Institute, Wako-shi, Saitama (Japan); Ashhab, S.; Nori, Franco [RIKEN Advanced Science Institute, Wako-shi, Saitama (Japan); Department of Physics, The University of Michigan, Ann Arbor, MI (United States)


    A transition between energy levels at an avoided crossing is known as a Landau-Zener transition. When a two-level system (TLS) is subject to periodic driving with sufficiently large amplitude, a sequence of transitions occurs. The phase accumulated between transitions (commonly known as the Stueckelberg phase) may result in constructive or destructive interference. Accordingly, the physical observables of the system exhibit periodic dependence on the various system parameters. This phenomenon is often referred to as Landau-Zener-Stueckelberg (LZS) interferometry. Phenomena related to LZS interferometry occur in a variety of physical systems. In particular, recent experiments on LZS interferometry in superconducting TLSs (qubits) have demonstrated the potential for using this kind of interferometry as an effective tool for obtaining the parameters characterizing the TLS as well as its interaction with the control fields and with the environment. Furthermore, strong driving could allow for fast and reliable control of the quantum system. Here we review recent experimental results on LZS interferometry, and we present related theory.

  1. New Aperture Partitioning Element (United States)

    Griffin, S.; Calef, B.; Williams, S.

    Postprocessing in an optical system can be aided by adding an optical element to partition the pupil into a number of segments. When imaging through the atmosphere, the recorded data are blurred by temperature-induced variations in the index of refraction along the line of sight. Using speckle imaging techniques developed in the astronomy community, this blurring can be corrected to some degree. The effectiveness of these techniques is diminished by redundant baselines in the pupil. Partitioning the pupil reduces the degree of baseline redundancy, and therefore improves the quality of images that can be obtained from the system. It is possible to implement the described approach on an optical system with a segmented primary mirror, but not very practical. This is because most optical systems do not have segmented primary mirrors, and those that do have relatively low bandwidth positioning of segments due to their large mass and inertia. It is much more practical to position an active aperture partitioning element at an aft optics pupil of the optical system. This paper describes the design, implementation and testing of a new aperture partitioning element that is completely reflective and reconfigurable. The device uses four independent, annular segments that can be positioned with a high degree of accuracy without impacting optical wavefront of each segment. This mirror has been produced and is currently deployed and working on the 3.6 m telescope.

  2. Tissue Harmonic Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Rasmussen, Joachim

    The main purpose of this PhD project is to develop an ultrasonic method for tissue harmonic synthetic aperture imaging. The motivation is to advance the field of synthetic aperture imaging in ultrasound, which has shown great potentials in the clinic. Suggestions for synthetic aperture tissue...... system complexity compared to conventional synthetic aperture techniques. In this project, SASB is sought combined with a pulse inversion technique for 2nd harmonic tissue harmonic imaging. The advantages in tissue harmonic imaging (THI) are expected to further improve the image quality of SASB...

  3. Synthetic-Aperture Silhouette Imaging (SASI) (United States)

    Paxman, R.


    The problem of ground-based fine-resolution imaging of geosynchronous satellites continues to be an important unsolved space-surveillance problem. We are investigating a passive-illumination approach that is radically different from amplitude, intensity, or heterodyne interferometry approaches. The approach, called Synthetic-Aperture Silhouette Imaging (SASI), produces a fine-resolution image of the satellite silhouette. When plane-wave radiation emanating from a bright star is occluded by a GEO satellite, then the light is diffracted and a moving diffraction pattern (shadow) is cast on the surface of the earth. With prior knowledge of the satellite orbit and star location, the track of the moving shadow can be predicted with high precision. A linear array of inexpensive hobby telescopes can be deployed roughly perpendicular to the shadow track to collect a time history of the star intensity as the shadow passes by. A phase-retrieval algorithm, using the strong constraint that the occlusion of the satellite is a binary-valued silhouette, allows us to retrieve the missing phase and reconstruct a fine-resolution image of the silhouette. Silhouettes are highly informative, providing diagnostic information about deployment of antennas and solar panels, enabling satellite pose estimation, and revealing the presence and orientation of neighboring satellites in rendezvous and proximity operations.

  4. 100-Picometer Interferometry for EUVL

    Energy Technology Data Exchange (ETDEWEB)

    Sommargren, G E; Phillion, D W; Johnson, M A; Nguyen, N O; Barty, A; Snell, F J; Dillon, D R; Bradsher, L S


    Future extreme ultraviolet lithography (EWL) steppers will, in all likelihood, have six-mirror projection cameras. To operate at the diffraction limit over an acceptable depth of focus each aspheric mirror will have to be fabricated with an absolute figure accuracy approaching 100 pm rms. We are currently developing visible light interferometry to meet this need based on modifications of our present phase shifting diffraction interferometry (PSDI) methodology where we achieved an absolute accuracy of 250pm. The basic PSDI approach has been further simplified, using lensless imaging based on computational diffractive back-propagation, to eliminate auxiliary optics that typically limit measurement accuracy. Small remaining error sources, related to geometric positioning, CCD camera pixel spacing and laser wavelength, have been modeled and measured. Using these results we have estimated the total system error for measuring off-axis aspheric EUVL mirrors with this new approach to interferometry.

  5. Phase Referencing in Optical Interferometry

    CERN Document Server

    Filho, Mercedes E; Duvert, Gilles; Duchene, Gaspard; Thiebaut, Eric; Young, John; Absil, Olivier; Berger, Jean-Phillipe; Beckert, Thomas; Hoenig, Sebastian; Schertl, Dieter; Weigelt, Gerd; Testi, Leonardo; Tatuli, Eric; Borkowski, Virginie; de Becker, Michael; Surdej, Jean; Aringer, Bernard; Hron, Joseph; Lebzelter, Thomas; Chiavassa, Andrea; Corradi, Romano; Harries, Tim


    One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and optical interferometry are at the two extremes of phase corruption by the atmosphere. While in radio it is possible to obtain calibrated phases for the science objects, in the optical this is currently not possible. Instead, optical interferometry has relied on closure phase techniques to produce images. Such techniques allow only to achieve modest dynamic ranges. However, with high contrast objects, for faint targets or when structure detail is needed, phase referencing techniques as used in radio interferometry, should theoretically achieve higher dynamic ranges for the same number of telescopes. Our approach is not to provide evidence either for or against the hypothesis that phase referenced imaging gives better dynamic range than closure phase imaging. Instead we wish to explore the potential of this techniq...

  6. Masked hypertension: a systematic review. (United States)

    Bobrie, Guillaume; Clerson, Pierre; Ménard, Joël; Postel-Vinay, Nicolas; Chatellier, Gilles; Plouin, Pierre-François


    The purpose of this research was to review the literature on masked hypertension. Studies, reviews and editorials on masked hypertension were identified by PubMed, Pascal BioMed and Cochrane literature systematic searches. Then, we carried out a meta-analysis of the six cohort studies reporting quantitative data for masked hypertension prognosis. There is still no clear consensus definition of masked hypertension and the reproducibility of the phenomenon is unknown. Nevertheless, the prevalence of masked hypertension seems to lie between 8 and 20%, and can be up to 50% in treated hypertensive patients. Subjects with masked hypertension have a higher risk of cardiovascular accidents [hazard ratios: 1.92 (1.51-2.44)] than normotensive subjects. This is due to a possible failure to recognize and appropriately manage this particular form of hypertension, the frequent association with other risk factors and coexisting target organ damage. The remaining unresolved questions are as follows: is masked hypertension a clinical entity that requires identification and characterization or a statistical phenomenon linked to the variability of blood pressure measurements?; because screening of the entire population is not feasible, how to identify individuals with masked hypertension?; and, in the absence of randomized trial, how to treat masked hypertension?

  7. Trends in mask data preparation (United States)

    Fujimura, Aki; Pang, Liyong; Su, Bo; Choi, Yohan


    Whether for VSB mask writing or for multibeam mask writing, the shapes we need to write on masks are increasingly complex, increasingly curvilinear, and smaller in minimum width and space. The overwhelming trend in mask data preparation (MDP) is the shift from deterministic, rule-based, geometric, context-independent, shape-modulated, rectangular processing to statistical, simulation-based, context-dependent, dose- and shape-modulated any-shape processing. The paper briefly surveys the history of MDP, and explains through a simulation-based study that 50nm line and space is the tipping point where rule-based processing gives away to simulation-based processing.

  8. Techniques in Broadband Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D J


    This is a compilation of my patents issued from 1997 to 2002, generally describing interferometer techniques that modify the coherence properties of broad-bandwidth light and other waves, with applications to Doppler velocimetry, range finding, imaging and spectroscopy. Patents are tedious to read in their original form. In an effort to improve their readability I have embedded the Figures throughout the manuscript, put the Figure captions underneath the Figures, and added section headings. Otherwise I have resisted the temptation to modify the words, though I found many places which could use healthy editing. There may be minor differences with the official versions issued by the US Patent and Trademark Office, particularly in the claims sections. In my shock physics work I measured the velocities of targets impacted by flyer plates by illuminating them with laser light and analyzing the reflected light with an interferometer. Small wavelength changes caused by the target motion (Doppler effect) were converted into fringe shifts by the interferometer. Lasers having long coherence lengths were required for the illumination. While lasers are certainly bright sources, and their collimated beams are convenient to work with, they are expensive. Particularly if one needs to illuminate a wide surface area, then large amounts of power are needed. Orders of magnitude more power per dollar can be obtained from a simple flashlamp, or for that matter, a 50 cent light bulb. Yet these inexpensive sources cannot practically be used for Doppler velocimetry because their coherence length is extremely short, i.e. their bandwidth is much too wide. Hence the motivation for patents 1 & 2 is a method (White Light Velocimetry) for allowing use of these powerful but incoherent lamps for interferometry. The coherence of the illumination is modified by passing it through a preparatory interferometer.

  9. Bandwidth in bolometric interferometry (United States)

    Charlassier, R.; Bunn, E. F.; Hamilton, J.-Ch.; Kaplan, J.; Malu, S.


    Context. Bolometric interferometry is a promising new technology with potential applications to the detection of B-mode polarization fluctuations of the cosmic microwave background (CMB). A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers to be competitive with imaging experiments. A crucial concern is that interferometers are assumed to be significantly affected by a spoiling effect known as bandwidth smearing. Aims: We investigate how the bandwidth modifies the work principle of a bolometric interferometer and affects its sensitivity to the CMB angular power spectra. Methods: We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. If the phase shifters produce shifts that are constant with respect to frequency, the instrument works like its monochromatic version (the modulation matrix is not modified), while if they vary (linearly or otherwise) with respect to frequency, one has to perform a special reconstruction scheme, which allows the visibilities to be reconstructed in frequency subbands. Using an angular power spectrum estimator that accounts for the bandwidth, we finally calculate the sensitivity of a broadband bolometric interferometer. A numerical simulation is performed that confirms the analytical results. Results: We conclude that (i) broadband bolometric interferometers allow broadband visibilities to be reconstructed regardless of the type of phase shifters used and (ii) for dedicated B-mode bolometric interferometers, the sensitivity loss caused by bandwidth smearing is quite acceptable, even for wideband instruments (a factor of 2 loss for a typical 20% bandwidth experiment).

  10. Measurement of large aspheric surfaces by annular subaperture stitching interferometry

    Institute of Scientific and Technical Information of China (English)

    Xiaokun Wang; Lihui Wang; Longhai Yin; Binzhi Zhang; Di Fan; Xuejun Zhang


    A new method for testing aspheric surfaces by annular subaperture stitching interferometry is introduced.It can test large-aperture and large-relative-aperture aspheric surfaces at high resolution, low cost, and high efficiency without auxiliary null optics. The basic principle of the method is described, the synthetical optimization stitching model and effective algorithm are established based on simultaneous least-square fitting. A hyperboloid with an aperture of 350 mm is tested by this method. The obtained peak-to-valley (PV) and root-mean-square (RMS) values of the surface error after stitching are 0.433λ and 0.052λ (λis 632.8 nm), respectively. The reconstructed surface map is coincide with the entire surface map from null test, and the difference of PV and RMS errors between them are 0.031λ and 0.005λ, respectively.This stitching model provides another quantitive method for testing large aspheric surfaces besides null compensation.

  11. Advanced methods in synthetic aperture radar imaging (United States)

    Kragh, Thomas


    For over 50 years our world has been mapped and measured with synthetic aperture radar (SAR). A SAR system operates by transmitting a series of wideband radio-frequency pulses towards the ground and recording the resulting backscattered electromagnetic waves as the system travels along some one-dimensional trajectory. By coherently processing the recorded backscatter over this extended aperture, one can form a high-resolution 2D intensity map of the ground reflectivity, which we call a SAR image. The trajectory, or synthetic aperture, is achieved by mounting the radar on an aircraft, spacecraft, or even on the roof of a car traveling down the road, and allows for a diverse set of applications and measurement techniques for remote sensing applications. It is quite remarkable that the sub-centimeter positioning precision and sub-nanosecond timing precision required to make this work properly can in fact be achieved under such real-world, often turbulent, vibrationally intensive conditions. Although the basic principles behind SAR imaging and interferometry have been known for decades, in recent years an explosion of data exploitation techniques enabled by ever-faster computational horsepower have enabled some remarkable advances. Although SAR images are often viewed as simple intensity maps of ground reflectivity, SAR is also an exquisitely sensitive coherent imaging modality with a wealth of information buried within the phase information in the image. Some of the examples featured in this presentation will include: (1) Interferometric SAR, where by comparing the difference in phase between two SAR images one can measure subtle changes in ground topography at the wavelength scale. (2) Change detection, in which carefully geolocated images formed from two different passes are compared. (3) Multi-pass 3D SAR tomography, where multiple trajectories can be used to form 3D images. (4) Moving Target Indication (MTI), in which Doppler effects allow one to detect and

  12. Phase estimation in optical interferometry

    CERN Document Server

    Rastogi, Pramod


    Phase Estimation in Optical Interferometry covers the essentials of phase-stepping algorithms used in interferometry and pseudointerferometric techniques. It presents the basic concepts and mathematics needed for understanding the phase estimation methods in use today. The first four chapters focus on phase retrieval from image transforms using a single frame. The next several chapters examine the local environment of a fringe pattern, give a broad picture of the phase estimation approach based on local polynomial phase modeling, cover temporal high-resolution phase evaluation methods, and pre

  13. What Is Being Masked in Object Substitution Masking? (United States)

    Gellatly, Angus; Pilling, Michael; Cole, Geoff; Skarratt, Paul


    Object substitution masking (OSM) is said to occur when a perceptual object is hypothesized that is mismatched by subsequent sensory evidence, leading to a new hypothesized object being substituted for the first. For example, when a brief target is accompanied by a longer lasting display of nonoverlapping mask elements, reporting of target…

  14. Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav; Gammelmark, Kim Løkke


    The paper describes the use of synthetic aperture (SA) imaging in medical ultrasound. SA imaging is a radical break with today's commercial systems, where the image is acquired sequentially one image line at a time. This puts a strict limit on the frame rate and the possibility of acquiring...... of SA imaging. Due to the complete data set, it is possible to have both dynamic transmit and receive focusing to improve contrast and resolution. It is also possible to improve penetration depth by employing codes during ultrasound transmission. Data sets for vector flow imaging can be acquired using...... short imaging sequences, whereby both the correct velocity magnitude and angle can be estimated. A number of examples of both phantom and in-vivo SA images will be presented measured by the experimental ultrasound scanner RASMUS to demonstrate the many benefits of SA imaging....

  15. Synthetic Aperture Compound Imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk

    Medical ultrasound imaging is used for many purposes, e.g. for localizing and classifying cysts, lesions, and other processes. Almost any mass is first observed using B-mode imaging and later classified using e.g. color flow, strain, or attenuation imaging. It is therefore important that the B....... The method is investigated using simulations and through measurements using both phased array and convex array transducers. The images all show an improved contrast compared to images without compounding, and by construction, imaging using an improved frame rate is possible. Using a phased array transducer...... and the limiting factor is the amount of memory IO resources available. An equally high demand for memory throughput is found in the computer gaming industry, where a large part of the processing takes place on the graphics processing unit (GPU). Using the GPU, a framework for synthetic aperture imaging...

  16. SEMATECH EUVL mask program status (United States)

    Yun, Henry; Goodwin, Frank; Huh, Sungmin; Orvek, Kevin; Cha, Brian; Rastegar, Abbas; Kearney, Patrick


    As we approach the 22nm half-pitch (hp) technology node, the industry is rapidly running out of patterning options. Of the several lithography techniques highlighted in the International Technology Roadmap for Semiconductors (ITRS), the leading contender for the 22nm hp insertion is extreme ultraviolet lithography (EUVL). Despite recent advances with EUV resist and improvements in source power, achieving defect free EUV mask blank and enabling the EUV mask infrastructure still remain critical issues. To meet the desired EUV high volume manufacturing (HVM) insertion target date of 2013, these obstacles must be resolved on a timely bases. Many of the EUV mask related challenges remain in the pre-competitive stage and a collaborative industry based consortia, such as SEMATECH can play an important role to enable the EUVL landscape. SEMATECH based in Albany, NY is an international consortium representing several of the largest manufacturers in the semiconductor market. Full members include Intel, Samsung, AMD, IBM, Panasonic, HP, TI, UMC, CNSE (College of Nanoscience and Engineering), and Fuller Road Management. Within the SEMATECH lithography division a major thrust is centered on enabling the EUVL ecosystem from mask development, EUV resist development and addressing EUV manufacturability concerns. An important area of focus for the SEMATECH mask program has been the Mask Blank Development Center (MBDC). At the MBDC key issues in EUV blank development such as defect reduction and inspection capabilities are actively pursued together with research partners, key suppliers and member companies. In addition the mask program continues a successful track record of working with the mask community to manage and fund critical mask tools programs. This paper will highlight recent status of mask projects and longer term strategic direction at the MBDC. It is important that mask technology be ready to support pilot line development HVM by 2013. In several areas progress has been

  17. Holographically Correcting Synthetic Aperture Aberrations. (United States)


    Malacara (20:105-148). The synthetic aperture was aligned in accordance with the synthetic-aperture alignment technique of Gill (8:61-64). The...1987. 20. Malacara , Daniel, ed. Optical Shop Testing. New York: John Wiley & Sons, 1978. 21. Marciniak, Capt Michael. Tutorial Presentation of mV

  18. Shadow mask assisted heteroepitaxy of compound semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Schallenberg, T.


    Shadow Mask assisted Molecular Beam Epitaxy (SMMBE) is a technique enabling selected area epitaxy of semiconductor heterostructures through shadow masks. The objective of this work was the development of the SMMBE technique for the reliable fabrication of compound semiconductor nanostructures of high structural and optical quality. In order to accomplish this, technological processes have been developed and optimized. One of the technological developments to this effect, which has substantially enhanced the versatility of SMMBE, is the introduction of a new type of freestanding shadow masks. A consistent model has been developed, which successfully explains the growth dynamics of molecular beam epitaxy through shadow masks. The predictions of the model regarding the growth of II-VI and III-V compounds have been tested experimentally and the dependence of the growth rates on the growth parameters has been verified. Moreover, it has been shown, that selected area epitaxy of II-VI and III-V compounds are governed by different surface kinetics. In addition to the basic surface kinetic processes described by the model, the roles of orientation and strain-dependent growth dynamics, partial shadow, and material deposition on the mask (closure of apertures) have been discussed. The resulting advanced understanding of the growth dynamics (model and basic experiments) in combination with the implementation of technical improvements has enabled the development and application of a number of different processes for the fabrication of both II-VI and III-V nanostructures. In addition to specific material properties, various other phenomena have been exploited, e.g., self-organization. Bright cathodoluminescence demonstrates that the resulting quantum structures are of high structural and optical quality. In addition to these results the limitations of the method have also been discussed, and various approaches to overcome them have been suggested. Moreover, propositions for the

  19. The JWST/NIRCam Coronagraph: Mask Design and Fabrication (United States)

    Krista, John E.; Balasubramanian, Kunjithapatha; Beichman, Charles A.; Echternach, Pierre M.; Green, Joseph J.; Liewer, Kurt M.; Muller, Richard E.; Serabyn, Eugene; Shaklan, Stuart B.; Trauger, John T.; Wilson, Daniel W.; Horner, Scott D.; Mao, Yalan; Somerstein, Stephen F.; Vasudevan, Gopal; Kelly, Douglas M.; Rieke, Marcia J.


    The NIRCam instrument on the James Webb Space Telescope will provide coronagraphic imaging from lambda =1-5 microns of high contrast sources such as extrasolar planets and circumstellar disks. A Lyot coronagraph with a variety of circular and wedge-shaped occulting masks and matching Lyot pupil stops will be implemented. The occulters approximate grayscale transmission profiles using halftone binary patterns comprising wavelength-sized metal dots on anti-reflection coated sapphire substrates. The mask patterns are being created in the Micro Devices Laboratory at the Jet Propulsion Laboratory using electron beam lithography. Samples of these occulters have been successfully evaluated in a coronagraphic testbed. In a separate process, the complex apertures that form the Lyot stops will be deposited onto optical wedges. The NIRCam coronagraph flight components are expected to be completed this year.

  20. Masked Repetition Priming Using Magnetoencephalography (United States)

    Monahan, Philip J.; Fiorentino, Robert; Poeppel, David


    Masked priming is used in psycholinguistic studies to assess questions about lexical access and representation. We present two masked priming experiments using MEG. If the MEG signal elicited by words reflects specific aspects of lexical retrieval, then one expects to identify specific neural correlates of retrieval that are sensitive to priming.…

  1. Sparse synthetic aperture radar imaging with optimized azimuthal aperture

    Institute of Scientific and Technical Information of China (English)

    ZENG Cao; WANG MinHang; LIAO GuiSheng; ZHU ShengQi


    To counter the problem of acquiring and processing huge amounts of data for synthetic aperture radar (SAR) using traditional sampling techniques,a method for sparse SAR imaging with an optimized azimuthal aperture is presented.The equivalence of an azimuthal match filter and synthetic array beamforming is shown so that optimization of the azimuthal sparse aperture can be converted to optimization of synthetic array beamforming.The azimuthal sparse aperture,which is composed of a middle aperture and symmetrical bilateral apertures,can be obtained by optimization algorithms (density weighting and simulated annealing algorithms,respectively).Furthermore,sparse imaging of spectrum analysis SAR based on the optimized sparse aperture is achieved by padding zeros at null samplings and using a non-uniform Taylor window. Compared with traditional sampling,this method has the advantages of reducing the amount of sampling and alleviating the computational burden with acceptable image quality.Unlike periodic sparse sampling,the proposed method exhibits no image ghosts.The results obtained from airborne measurements demonstrate the effectiveness and superiority of the proposed method.

  2. AIPY: Astronomical Interferometry in PYthon (United States)

    Parsons, Aaron


    AIPY collects together tools for radio astronomical interferometry. In addition to pure-python phasing, calibration, imaging, and deconvolution code, this package includes interfaces to MIRIAD (ascl:1106.007) and HEALPix (ascl:1107.018), and math/fitting routines from SciPy.

  3. Virtual Reference Interferometry: Theory & Experiment (United States)

    Galle, Michael Anthony

    This thesis introduces the idea that a simulated interferogram can be used as a reference for an interferometer. This new concept represents a paradigm shift from the conventional thinking, where a reference is the phase of a wavefront that traverses a known path. The simulated interferogram used as a reference is called a virtual reference. This thesis develops the theory of virtual reference interferometry and uses it for the characterization of chromatic dispersion in short length (virtual reference combines the advantages of these techniques so that it is both accurate and easy to operate. Chromatic dispersion measurements based on virtual reference interferometry have similar accuracy as the best conventional measurement techniques due to the ability to measure first and second order dispersion directly from the interference pattern. Unique capabilities of virtual reference interferometry are demonstrated, followed by a derivation of the operational constraints and system parameters. The technique is also applied to the characterization of few-mode fibers, a hot topic in telecommunications research where mode division multiplexing promises to expand network bandwidth. Also introduced is the theory of dispersive virtual reference interferometry, which can be used to overcome the bandwidth limitations associated with the measurement of near-zero dispersion-length optical components via compression of the interference pattern. Additionally, a method for utilizing the virtual reference interferometer in a low-coherence setup is introduced, enabling characterization in new wavelength ranges and further reducing the cost of characterization.

  4. New Methods in Moire Interferometry (United States)

    Czarnek, Robert

    Experimental observations and measurements are the essential source of information necessary for correct development of mathematical models of real materials. Moire interferometry offers high sensitivity in full-field measurements of the in-plane displacements on the surface of the specimen. The (+OR-)45(DEGREES) method of moire interferometry increases the efficiency of a three-beam interferometer making its use outside of an optical laboratory more practical. Analysis of the (+OR-)45(DEGREES) method is provided. A concept of the vector representation of the fringe gradient is introduced and used in the analysis. Although existing systems require coherent light, the proposed system can use a relatively broad spectral bandwidth. Features that are related to the vibration sensitivity of such an instrument are investigated analytically. The basic concepts of an achromatic moire interferometry system are developed. Attachment of the critical elements of the system to the specimen solves the problem of relative rigid body motions, including vibrations, between the specimen and the virtual reference grating. Application of a laser diode light source reduces size, weight and cost of the interferometer making moire interferometry more practical for most materials testing laboratories. Laboratory tests confirmed the developed methods. This work enhances the probability of successful construction of a portable moire interferometer for measurements outside of the optical laboratory, in a mechanical testing or field environment.

  5. Vector wave diffraction pattern of slits masked by polarizing devices

    Indian Academy of Sciences (India)

    Mohammad Tahir; K Bhattacharya; A K Chakraborty


    Polarization property is important to the optical imaging system. It has recently been understood that the polarization properties of light can be fruitfully used for improving the characteristics of imaging system that includes polarizing devices. The vector wave imagery lends an additional degree of freedom that can be utilized for obtaining results that are unobtainable in scalar wave imagery. This calls for a systematic study of diffraction properties of different apertures using polarization-sensitive devices. In the present paper, we have studied the Fraunhofer diffraction pattern of slits masked by different kinds of polarizing devices which introduce a phase difference between the two orthogonal components of the incident beam.

  6. Bam earthquake: Surface deformation measurement using radar interferometry

    Institute of Scientific and Technical Information of China (English)

    XIA Ye


    On the 26th December 2003 an earthquake with Mw=6.5 shook a large area of the Kerman Province in Iran. The epicenter of the devastating earthquake was located near the city of Bam. This paper described the application of differential synthetic aperture radar interferometry (D-INSAR) and ENVISAT ASAR data to map the coseismic surface deformation caused by the Bam earthquake including the interferometric data processing and results in detail. Based on the difference in the coherence images before and after the event and edge search of the deformation field, a new fault ruptured on the surface was detected and used as a data source for parameter extraction of a theoretical seismic modeling. The simulated deformation field from the model perfectly coincides with the result derived from the SAR interferometric measurement.

  7. Biological Activity of Masked Endotoxin (United States)

    Schwarz, Harald; Gornicec, Jan; Neuper, Theresa; Parigiani, Maria Alejandra; Wallner, Michael; Duschl, Albert; Horejs-Hoeck, Jutta


    Low endotoxin recovery (LER) is a recently discovered phenomenon describing the inability of limulus amebocyte lysate (LAL)-based assays to detect lipopolysaccharide (LPS) because of a “masking effect” caused by chelators or detergents commonly used in buffer formulations for medical products and recombinant proteins. This study investigates the masking capacities of different buffer formulations and whether masked endotoxin is biologically active. We show that both naturally occurring endotoxin as well as control standard endotoxin can be affected by LER. Furthermore, whereas masked endotoxin cannot be detected in Factor C based assays, it is still detectable in a cell-based TLR4-NF-κB-luciferase reporter gene assay. Moreover, in primary human monocytes, masked LPS induces the expression of pro-inflammatory cytokines and surface activation markers even at very low concentrations. We therefore conclude that masked LPS is a potent trigger of immune responses, which emphasizes the potential danger of masked LPS, as it may pose a health threat in pharmaceutical products or compromise experimental results. PMID:28317862

  8. Super-virtual refraction interferometry: Theory

    KAUST Repository

    Bharadwaj, Pawan


    Inverting for the subsurface velocity distribution by refraction traveltime tomography is a well-accepted imaging method by both the exploration and earthquake seismology communities. A significant drawback, however, is that the recorded traces become noisier with increasing offset from the source position, and so prevents accurate picking of traveltimes in far-offset traces. To enhance the signal-to-noise ratio of the far-offset traces, we present the theory of super-virtual refraction interferometry where the signal-to-noise ratio (SNR) of far-offset head-wave arrivals can be theoretically increased by a factor proportional to N; here, N is the number of receiver and source positions associated with the recording and generation of the head-wave arrival. There are two steps to this methodology: correlation and summation of the data to generate traces with virtual head-wave arrivals, followed by the convolution of the data with the virtual traces to create traces with super-virtual head-wave arrivals. This method is valid for any medium that generates head-wave arrivals. There are at least three significant benefits to this methodology: 1). enhanced SNR of far-offset traces so the first-arrival traveltimes of the noisy far-offset traces can be more reliably picked to extend the useful aperture of data, 2). the SNR of head waves in a trace that arrive after the first arrival can be enhanced for accurate traveltime picking and subsequent inversion by traveltime tomography, and 3). common receiver-pair gathers can be analyzed to detect the presence of diving waves in the first arrivals, which can be used to assess the nature of the refracting boundary. © 2011 Society of Exploration Geophysicists.

  9. Hg-Mask Coronagraph (United States)

    Bourget, P.; Veiga, C. H.; Vieira Martins, R.; Assus, P.; Colas, F.

    In order to optimize the occulting process of a Lyot coronagraph and to provide a high dynamic range imaging, a new kind of occulting disk has been developed at the National Observatory of Rio de Janeiro. A mercury (Hg) drop glued onto an optical window by molecular cohesion and compressed by a pellicle film is used as the occulting disk. The minimum of the superficial tension potential function provides an optical precision (lambda/100) of the toric free surface of the mercury. This process provides a size control for the adaptation to the seeing conditions and to the apparent diameter of a resolved object, and in the case of adaptive optics, to the Airy diameter fraction needed. The occultation is a three dimensional process near the focal plane on the toric free surface that provides an apodization of the occultation. The Hg-Mask coronagraph has been projected for astrometric observations of faint satellites near to Jovian planets and works since 2000 at the 1.6 m telescope of the Pico dos Dias Observatory (OPD - Brazil).

  10. Interferometry meets the third and fourth dimensions in galaxies

    CERN Document Server

    Trimble, Virginia


    Radio astronomy began with one array (Jansky's) and one paraboloid of revolution (Reber's) as collecting areas and has now reached the point where a large number of facilities are arrays of paraboloids, each of which would have looked enormous to Reber in 1932. In the process, interferometry has contributed to the counting of radio sources, establishing superluminal velocities in AGN jets, mapping of sources from the bipolar cow shape on up to full grey-scale and colored images, determining spectral energy distributions requiring non-thermal emission processes, and much else. The process has not been free of competition and controversy, at least partly because it is just a little difficult to understand how earth-rotation, aperture-synthesis interferometry works. Some very important results, for instance the mapping of HI in the Milky Way to reveal spiral arms, warping, and flaring, actually came from single moderate-sized paraboloids. The entry of China into the radio astronomy community has given large (40-...

  11. Mechanical alignment of substrates to a mask

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Aaron P.; Carlson, Charles T.; Honan, Michael; Amato, Luigi G.; Grant, Christopher Neil; Strassner, James D.


    A plurality of masks is attached to the underside of a mask frame. This attachment is made such that each mask can independently move relative to the mask frame in three directions. This relative movement allows each mask to adjust its position to align with respective alignment pins disposed on a working surface. In one embodiment, each mask is attached to the mask frame using fasteners, where the fasteners have a shaft with a diameter smaller than the diameter of the mounting hole disposed on the mask. A bias element may be used to allow relative movement between the mask and the mask frame in the vertical direction. Each mask may also have kinematic features to mate with the respective alignment pins on the working surface.

  12. Vibrotactile masking through the body. (United States)

    D'Amour, Sarah; Harris, Laurence R


    Touches on one hand or forearm can affect tactile sensitivity at contralateral locations on the opposite side of the body. These interactions suggest an intimate connection between the two sides of the body. Here, we explore the effect of masking not across the body but through the body by measuring the effect of a masking stimulus on the back on the tactile sensitivity of the corresponding point on the front. Tactile sensitivity was measured on each side of the stomach, while vibrotactile masking stimulation was applied to one side of the front and to points on the back including the point directly behind the test point on the front. Results were compared to sensitivity, while vibrotactile stimulation was applied to a control site on the shoulder. A reduction in sensitivity of about .8 dB was found that required the masking stimulus to be within about 2 cm of the corresponding point on the back.

  13. A demonstrator for bolometric interferometry

    CERN Document Server

    Ghribi, Adnan; Galli, Silvia; Piat, Michel; Breelle, Eric; Hamilton, Jean-Christophe; Spinelli, Sebastiano; Gervasi, Massimo; Zannoni, Mario


    Bolometric Interferometry (BI) is one of the most promising techniques for precise measurements of the Cosmic Microwave Background polarization. In this paper, we present the results of DIBO (Demonstrateur d'Interferometrie Bolometrique), a single-baseline demonstrator operating at 90 GHz, built to proof the validity of the BI concept applied to a millimeter-wave interferometer. This instrument has been characterized in the laboratory with a detector at room temperature and with a 4 K bolometer. This allowed us to measure interference patterns in a clean way, both (1) rotating the source and (2) varying with time the phase shift among the two interferometer's arms. Detailed modelisation has also been performed and validated with measurements.

  14. Holographic interferometry in construction analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hartikainen, T.


    In this work techniques for visualizing phase and opaque objects by ruby laser interferometry are introduced. A leakage flow as a phase object is studied by holographic interferometry and the intensity distribution of the interferograms presenting the leakage flow are computer-simulated. A qualitative and quantitative analysis of the leakage flow is made. The analysis is based on the experimental and theoretical results presented in this work. The holographic setup and the double pass method for visualizing leakage flow are explained. A vibrating iron plate is the opaque object. Transient impact waves are generated by a pistol bullet on the iron plate and visualized by holographic interferometry. An apparatus with the capability of detecting and calculating the delays necessary for laser triggering is introduced. A time series of interferograms presenting elastic wave formation in an iron plate is shown. A computer-simulation of the intensity distributions of these interferograms is made. An analysis based on the computer-simulation and the experimental data of the transient elastic wave is carried out and the results are presented. (author)

  15. Recent Advances in Radar Polarimetry and Polarimetric SAR Interferometry (United States)

    Boerner, Wolfgang-Martin


    The development of Radar Polarimetry and Radar Interferometry is advancing rapidly, and these novel radar technologies are revamping Synthetic Aperture Radar Imaging decisively. In this exposition the successive advancements are sketched; beginning with the fundamental formulations and high-lighting the salient points of these diverse remote sensing techniques. Whereas with radar polarimetry the textural fine-structure, target-orientation and shape, symmetries and material constituents can be recovered with considerable improvements above that of standard amplitude-only Polarization Radar ; with radar interferometry the spatial (in depth) structure can be explored. In Polarimetric-Interferometric Synthetic Aperture Radar (POL-IN-SAR) Imaging it is possible to recover such co-registered textural plus spatial properties simultaneously. This includes the extraction of Digital Elevation Maps (DEM) from either fully Polarimetric (scattering matrix) or Interferometric (dual antenna) SAR image data takes with the additional benefit of obtaining co-registered three-dimensional POL-IN-DEM information. Extra-Wide-Band POL-IN-SAR Imaging - when applied to Repeat-Pass Image Overlay Interferometry - provides differential background validation and measurement, stress assessment, and environmental stress-change monitoring capabilities with hitherto unattained accuracy, which are essential tools for improved global biomass estimation. More recently, by applying multiple parallel repeat-pass EWB-POL-D(RP)-IN-SAR imaging along stacked (altitudinal) or displaced (horizontal) flight-lines will result in Tomographic (Multi- Interferometric) Polarimetric SAR Stereo-Imaging , including foliage and ground penetrating capabilities. It is shown that the accelerated advancement of these modern EWB-POL-D(RP)-IN-SAR imaging techniques is of direct relevance and of paramount priority to wide-area dynamic homeland security surveillance and local-to-global environmental ground-truth measurement

  16. Advances in space-borne SAR interferometry and its application to ground deformation monitoring

    Institute of Scientific and Technical Information of China (English)

    LIU Zhen-guo; BIAN Zheng-fu


    The development of Differential Synthetic Aperture Radar Interferometry (D-InSAR), in terms of its evolution from classic to advanced forms, such as Least-Squares approach, Permanent Scatterer Interferometry, Small Baseline Subset, and Coherent Pixel Technique, is reviewed, describing concisely the main principles of each method and highlighting the difference and relationship between them. Applications of InSAR technology in China were then introduced, together with the obstacles to overcome and feasible strategies, such as integrating MERIS/MODIS data to compensate for the atmospheric effect and GPS, and multi-platform SAR data to make InSAR technique practical and operational under various conditions. The latest developments were then analyzed along with high-quality SAR data, available thanks to the newly launched high-tech satellites, TerraSAR-X, and Cosmo Sky-med, and conclusions were drawn about the main limitations of the technique.

  17. Operational Monitoring of Mines by COSMO-SkyMed PSP SAR Interferometry (United States)

    Costantini, Mario; Malvarosa, Fabio; Miniati, Federico; de Assis, Luciano Mozer


    Synthetic aperture radar (SAR) interferometry is a powerful technology for detection and monitoring of slow ground surface movements. Monitoring of ground deformations in mining structures is an important application, particularly difficult because the scene changes with time. The persistent scatterer pair (PSP) approach, recently proposed to overcome some limitations of standard persistent scatter interferometry, proved to be effective also for mine monitoring. In this work, after resuming the main ideas of the PSP method, we describe the PSP measurements obtained from high- resolution X-band COSMO-SkyMed data over a large mining area in Minas Gerais state, Brazil. The outcomes demonstrate that dense and accurate ground deformation measurements can be obtained on the mining area and its structures (such as open pits, waste dumps, conveyor belts, water and tailings dams, etc.), achieving a consistent global view including also areas where field instruments are not installed.

  18. Research on 3D marine electromagnetic interferometry with synthetic sources for suppressing the airwave interference

    Institute of Scientific and Technical Information of China (English)

    Zhang Jian-Guo; Wu Xin; Qi You-Zheng; Huang Ling; Fang Guang-You


    In order to suppress the airwave noise in marine controlled-source electromagnetic (CSEM) data, we propose a 3D deconvolution (3DD) interferometry method with a synthetic aperture source and obtain the relative anomaly coefficient (RAC) of the EM field reflection responses to show the degree for suppressing the airwave. We analyze the potential of the proposed method for suppressing the airwave, and compare the proposed method with traditional methods in their effectiveness. A method to select synthetic source length is derived and the effect of the water depth on RAC is examined via numerical simulations. The results suggest that 3DD interferometry method with a synthetic source can effectively suppress the airwave and enhance the potential of marine CSEM to hydrocarbon exploration.

  19. An imaging interferometry capability for the EISCAT Svalbard Radar

    Directory of Open Access Journals (Sweden)

    T. Grydeland


    Full Text Available Interferometric imaging (aperture synthesis imaging is a technique used by radio astronomers to achieve angular resolution that far surpasses what is possible with a single large aperture. A similar technique has been used for radar imaging studies of equatorial ionospheric phenomena at the Jicamarca Radio Observatory. We present plans for adding an interferometric imaging capability to the EISCAT Svalbard Radar (ESR, a capability which will contribute significantly to several areas of active research, including naturally and artificially enhanced ion-acoustic echoes and their detailed relation in space and time to optical phenomena, polar mesospheric summer echoes (PMSE, and meteor studies.

    Interferometry using the two antennas of the ESR has demonstrated the existence of extremely narrow, field-aligned scattering structures, but having only a single baseline is a severe limitation for such studies. Building additional IS-class antennas at the ESR is not a trivial task. However, the very high scattering levels in enhanced ion-acoustic echoes and PMSE means that a passive receiver antenna of more modest gain should still be capable of detecting these echoes.

    In this paper we present simulations of what an imaging interferometer will be capable of observing for different antenna configurations and brightness distributions, under ideal conditions, using two different image inversion algorithms. We also discuss different antenna and receiver technologies.

  20. Multi-static MIMO along track interferometry (ATI) (United States)

    Knight, Chad; Deming, Ross; Gunther, Jake


    Along-track interferometry (ATI) has the ability to generate high-quality synthetic aperture radar (SAR) images and concurrently detect and estimate the positions of ground moving target indicators (GMTI) with moderate processing requirements. This paper focuses on several different ATI system configurations, with an emphasis on low-cost configurations employing no active electronic scanned array (AESA). The objective system has two transmit phase centers and four receive phase centers and supports agile adaptive radar behavior. The advantages of multistatic, multiple input multiple output (MIMO) ATI system configurations are explored. The two transmit phase centers can employ a ping-pong configuration to provide the multistatic behavior. For example, they can toggle between an up and down linear frequency modulated (LFM) waveform every other pulse. The four receive apertures are considered in simple linear spatial configurations. Simulated examples are examined to understand the trade space and verify the expected results. Finally, actual results are collected with the Space Dynamics Laboratorys (SDL) FlexSAR system in diverse configurations. The theory, as well as the simulated and actual SAR results, are presented and discussed.

  1. Enhancing core-diffracted arrivals by supervirtual interferometry

    KAUST Repository

    Bharadwaj, P.


    A supervirtual interferometry (SVI) method is presented that can enhance the signal-to-noise ratio (SNR) of core diffracted waveforms by as much as O( √ N), where N is the number of inline receivers that record the core-mantle boundary (CMB) diffractions from more than one event. Here, the events are chosen to be approximately inline with the receivers along the same great circle. Results with synthetic and teleseismic data recorded by USArray stations demonstrate that formerly unusable records with low SNR can be transformed to high SNR records with clearly visible CMB diffractions. Another benefit is that SVI allows for the recording of a virtual earthquake at stations not deployed during the time of the earthquake. This means that portable arrays such as USArray can extend the aperture of one recorded earthquake from the West coast to the East coast, even though the teleseism might have only been recorded during theWest coast deployment. In summary, SVI applied to teleseismic data can significantly enlarge the catalogue of usable records both in SNR and available aperture for analysing CMB diffractions. A potential drawback of this method is that it generally provides the correct kinematics of CMB diffractions, but does not necessarily preserve correct amplitude information. © The Authors 2013. Published by Oxford University Press on behalf of The Royal Astronomical Society.

  2. Lyot-plane phase masks for improved high-contrast imaging with a vortex coronagraph

    CERN Document Server

    Ruane, Garreth J; Absil, Olivier; Mawet, Dimitri; Delacroix, Christian; Carlomagno, Brunella; Swartzlander, Grover A


    The vortex coronagraph is an optical instrument that precisely removes on-axis starlight allowing for high contrast imaging at small angular separation from the star, thereby providing a crucial capability for direct detection and characterization of exoplanets and circumstellar disks. Telescopes with aperture obstructions, such as secondary mirrors and spider support structures, require advanced coronagraph designs to provide adequate starlight suppression. We introduce a phase-only Lyot-plane optic to the vortex coronagraph that offers improved contrast performance on telescopes with complicated apertures. Potential solutions for the European Extremely Large Telescope (E-ELT) are described and compared. Adding a Lyot-plane phase mask relocates residual starlight away from a region of the image plane thereby reducing stellar noise and improving sensitivity to off-axis companions. The phase mask is calculated using an iterative phase retrieval algorithm. Numerically, we achieve a contrast on the order of $10^...

  3. Contralateral tactile masking between forearms. (United States)

    D'Amour, Sarah; Harris, Laurence R


    Masking effects have been demonstrated in which tactile sensitivity is affected when one touch is close to another on the body surface. Such effects are likely a result of local lateral inhibitory circuits that sharpen the spatial tuning of a given tactile receptor. Mutually inhibitory pathways have also been demonstrated between cortical tactile maps of the two halves of the body. Occasional reports have indicated that touches on one hand or forearm can affect tactile sensitivity at contralateral locations. Here, we measure the spatial tuning and effect of posture on this contralateral masking effect. Tactile sensitivity was measured on one forearm, while vibrotactile masking stimulation was applied to the opposite arm. Results were compared to sensitivity while vibrotactile stimulation was applied to a control site on the right shoulder. Sensitivity on the forearm was reduced by over 3 dB when the arms were touching and by 0.52 dB when they were held parallel. The masking effect depended on the position of the masking stimulus. Its effectiveness fell off by 1 STD when the stimulus was 29 % of arm length from the corresponding contralateral point. This long-range inhibitory effect in the tactile system suggests a surprisingly intimate relationship between the two sides of the body.

  4. Self-Rescue Mask Training

    CERN Multimedia


    Nine new self-rescue mask instructors have been trained since early 2013, which provides CERN with a total of 26 self-rescue mask instructors to date. This will allow us to meet the increasing training needs caused by the Long Shut Down LS1.   The self-rescue mask instructors have trained 1650 persons in 2012 and about 500 persons since the beginning of the year on how to wear the masks properly. We thank all the instructors and all the persons that made this training possible. Please remember that the self-rescue masks training sessions are scheduled as follows: Basic course: Tuesday and Thursday mornings (2 sessions – 8.30 AM and 10.30 AM), duration:  1.30 hour, in French and English – registration via CERN online training catalogue – Course code 077Y00. Refresher training : Monday mornings (2 sessions – 8.30 AM and 10.30 AM), duration: 1.30 hour , in French and English – registration via CERN online training catalogue &...

  5. Interferometric synthetic aperture radar imagery of the Gulf Stream (United States)

    Ainsworth, T. L.; Cannella, M. E.; Jansen, R. W.; Chubb, S. R.; Carande, R. E.; Foley, E. W.; Goldstein, R. M.; Valenzuela, G. R.


    The advent of interferometric synthetic aperture radar (INSAR) imagery brought to the ocean remote sensing field techniques used in radio astronomy. Whilst details of the interferometry differ between the two fields, the basic idea is the same: Use the phase information arising from positional differences of the radar receivers and/or transmitters to probe remote structures. The interferometric image is formed from two complex synthetic aperture radar (SAR) images. These two images are of the same area but separated in time. Typically the time between these images is very short -- approximately 50 msec for the L-band AIRSAR (Airborne SAR). During this short period the radar scatterers on the ocean surface do not have time to significantly decorrelate. Hence the two SAR images will have the same amplitude, since both obtain the radar backscatter from essentially the same object. Although the ocean surface structure does not significantly decorrelate in 50 msec, surface features do have time to move. It is precisely the translation of scattering features across the ocean surface which gives rise to phase differences between the two SAR images. This phase difference is directly proportional to the range velocity of surface scatterers. The constant of proportionality is dependent upon the interferometric mode of operation.

  6. Passive seismic interferometry by multidimensional deconvolution

    NARCIS (Netherlands)

    Wapenaar, C.P.A.; Van der Neut, J.R.; Ruigrok, E.N.


    We introduce seismic interferometry of passive data by multidimensional deconvolution (MDD) as an alternative to the crosscorrelation method. Interferometry by MDD has the potential to correct for the effects of source irregularity, assuming the first arrival can be separated from the full response.

  7. Digital Holographic Interferometry for Airborne Particle Characterization (United States)


    hologram and its extinction cross section, and a computational demonstration that holographic interferometry can resolve aerosol particle size ...holographic interferometry can resolve aerosol particle size evolution. (a) Papers published in peer-reviewed journals (N/A for none) Enter List of...Characterization of Atmospheric Aerosols workshop, Smolenice, Slovak Republic (2013). 7. Poster : Digital Holographic Imaging of Aerosol Particles In-Flight

  8. Progress in Interferometry for LISA at JPL

    CERN Document Server

    Spero, Robert; de Vine, Glenn; Dickson, Jeffrey; Klipstein, William; Ozawa, Tetsuo; McKenzie, Kirk; Shaddock, Daniel; Robison, David; Sutton, Andrew; Ware, Brent


    Recent advances at JPL in experimentation and design for LISA interferometry include the demonstration of Time Delay Interferometry using electronically separated end stations, a new arm-locking design with improved gain and stability, and progress in flight readiness of digital and analog electronics for phase measurements.

  9. Progress in interferometry for LISA at JPL

    Energy Technology Data Exchange (ETDEWEB)

    Spero, Robert; Bachman, Brian; De Vine, Glenn; Dickson, Jeffrey; Klipstein, William; Ozawa, Tetsuo; McKenzie, Kirk; Shaddock, Daniel; Robison, David; Ware, Brent [Jet Propulsion Laboratory (JPL), California Institute of Technology, 4800 Oak Grove Drive Pasadena, CA 91109 (United States); Sutton, Andrew, E-mail: [Centre for Gravitational Physics, The Australian National University, ACT 0200 (Australia)


    Recent advances at JPL in experimentation and design for LISA interferometry include the demonstration of time delay interferometry using electronically separated end stations, a new arm-locking design with improved gain and stability, and progress in flight readiness of digital and analog electronics for phase measurements.

  10. Dynamic optical aberration correction with adaptive coded apertures techniques in conformal imaging (United States)

    Li, Yan; Hu, Bin; Zhang, Pengbin; Zhang, Binglong


    Conformal imaging systems are confronted with dynamic aberration in optical design processing. In classical optical designs, for combination high requirements of field of view, optical speed, environmental adaption and imaging quality, further enhancements can be achieved only by the introduction of increased complexity of aberration corrector. In recent years of computational imaging, the adaptive coded apertures techniques which has several potential advantages over more traditional optical systems is particularly suitable for military infrared imaging systems. The merits of this new concept include low mass, volume and moments of inertia, potentially lower costs, graceful failure modes, steerable fields of regard with no macroscopic moving parts. Example application for conformal imaging system design where the elements of a set of binary coded aperture masks are applied are optimization designed is presented in this paper, simulation results show that the optical performance is closely related to the mask design and the reconstruction algorithm optimization. As a dynamic aberration corrector, a binary-amplitude mask located at the aperture stop is optimized to mitigate dynamic optical aberrations when the field of regard changes and allow sufficient information to be recorded by the detector for the recovery of a sharp image using digital image restoration in conformal optical system.

  11. Sequential Beamforming Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Kortbek, Jacob; Jensen, Jørgen Arendt; Gammelmark, Kim Løkke


    Synthetic aperture sequential beamforming (SASB) is a novel technique which allows to implement synthetic aperture beamforming on a system with a restricted complexity, and without storing RF-data. The objective is to improve lateral resolution and obtain a more depth independent resolution...... and a range independent lateral resolution is obtained. The SASB method has been investigated using simulations in Field II and by off-line processing of data acquired with a commercial scanner. The lateral resolution increases with a decreasing F#. Grating lobes appear if F# 6 2 for a linear array with k-pitch...

  12. Monitoring Land Subsidence over Mining Areas with Sentinel-1 Differential SAR Interferometry (United States)

    Mirek, Katarzna


    This paper presents possibilities for monitoring man- made surface deformation on example of two areas (Fig. 1): Upper Silesian Coal Basin and Lubelskie Coal Basin (Poland). Synthetic Aperture Radar (SAR) images acquired by Sentinel-1A satellite are utilized in subsidence studies. Satellite radar interferometry technique (InSAR) was used to detecting and monitoring subsidence. There are clearly visible on obtained interferograms subsidence troughs as a distinctive concentric fringes. This study is a part of initiated the SSUMMO project (Surface Subsidence Multidisciplinary Monitoring). The project will provide multidisciplinary monitoring of mining areas and it will prepare the methodology and research software for continuous observation of the impact of exploitation on surface.

  13. Advances in understanding young high-mass stars using optical interferometry

    CERN Document Server

    de Wit, W J


    The closest examples of high-mass star birth occurs in deeply embedded environments at kiloparsec distances. Although much progress has been made, an observationally validated picture of the dominant processes which allows the central hydrostatic object to grow in mass has yet to be established. The observational technique of optical interferometry has demonstrated its potential in the field of high-mass star formation by delivering a milli-arcsecond infrared view on the complex accretion environment. We provide an overview of the scientific results obtained with multi-aperture telescope arrays and briefly discuss future instruments and their anticipated impact on our understanding of massive young stellar objects.

  14. Golographic interferometry of physical processes (United States)

    Ostrovskaya, G. V.


    This paper is devoted to the contribution of Yuri Ostrovsky to holographic interferometry, one of the fundamental scientific and practical applications of holography. The title of this paper is the same as the title of his doctoral thesis that he defended in 1974, and, as it seems to me, reflects most of the specific features of the majority of his scientific publications, viz., an inseparable link of the methods developed by him with the results obtained with the help of these methods in a wide range of investigations of physical processes and phenomena.

  15. Radar interferometry persistent scatterer technique

    CERN Document Server

    Kampes, Bert M


    Only book on Permanent Scatterer technique of radar interferometryExplains the Permanent Scatterer technique in detail, possible pitfalls, and details a newly developed stochastic model and estimator algorithm to cope with possible problems for the application of the PS techniqueThe use of Permanent Scatterer allows very precise measurements of the displacement of hundreds of points per square kilometerDescribes the only technique currently able to perform displacement measurements in the past, utilizing the ERS satellite data archive using data acquired from 1992-prese

  16. Vibration analysis using moire interferometry (United States)

    Asundi, A.; Cheung, M. T.

    The present use of moire interferometry for low amplitude vibration and analysis demonstrates the possibility of obtaining out-of-plane displacement contours whose sensitivity is comparable to that of holographic methods. A major advantage of the present system, is the obviation of prior knowledge of resonant frequencies, as called for in time-average holography. The experimental apparatus employed encompasses a laser beam, a parabolic mirror, a high frequency (600 line/mm) grating, and a camera, in addition to the test model.

  17. An Interferometry Imaging Beauty Contest (United States)

    Lawson, Peter R.; Cotton, William D.; Hummel, Christian A.; Monnier, John D.; Zhaod, Ming; Young, John S.; Thorsteinsson, Hrobjartur; Meimon, Serge C.; Mugnier, Laurent; LeBesnerais, Guy; Thiebaut, Eric; Tuthill, Peter G.; Hani, Christopher A.; Pauls, Thomas; DuvertI, Gilles; Garcia, Paulo; Kuchner, Marc


    We present a formal comparison of the performance of algorithms used for synthesis imaging with optical/infrared long-baseline interferometers. Six different algorithms are evaluated based on their performance with simulated test data. Each set of test data is formated in the interferometry Data Exchange Standard and is designed to simulate a specific problem relevant to long-baseline imaging. The data are calibrated power spectra and bispectra measured with a ctitious array, intended to be typical of existing imaging interferometers. The strengths and limitations of each algorithm are discussed.

  18. Informational masking and musical training. (United States)

    Oxenham, Andrew J; Fligor, Brian J; Mason, Christine R; Kidd, Gerald


    The relationship between musical training and informational masking was studied for 24 young adult listeners with normal hearing. The listeners were divided into two groups based on musical training. In one group, the listeners had little or no musical training; the other group was comprised of highly trained, currently active musicians. The hypothesis was that musicians may be less susceptible to informational masking, which is thought to reflect central, rather than peripheral, limitations on the processing of sound. Masked thresholds were measured in two conditions, similar to those used by Kidd et al. [J. Acoust. Soc. Am. 95, 3475-3480 (1994)]. In both conditions the signal was comprised of a series of repeated tone bursts at 1 kHz. The masker was comprised of a series of multitone bursts, gated with the signal. In one condition the frequencies of the masker were selected randomly for each burst; in the other condition the masker frequencies were selected randomly for the first burst of each interval and then remained constant throughout the interval. The difference in thresholds between the two conditions was taken as a measure of informational masking. Frequency selectivity, using the notched-noise method, was also estimated in the two groups. The results showed no difference in frequency selectivity between the two groups, but showed a large and significant difference in the amount of informational masking between musically trained and untrained listeners. This informational masking task, which requires no knowledge specific to musical training (such as note or interval names) and is generally not susceptible to systematic short- or medium-term training effects, may provide a basis for further studies of analytic listening abilities in different populations.

  19. Production mask composition checking flow (United States)

    Ma, Shou-Yuan; Yang, Chuen-Huei; Tsai, Joe; Wang, Alice; Lin, Roger; Lee, Rachel; Deng, Erwin; Lin, Ling-Chieh; Liao, Hung-Yueh; Tsai, Jenny; Bowhill, Amanda; Vu, Hien; Russell, Gordon


    The mask composition checking flow is an evolution of the traditional mask rule check (MRC). In order to differentiate the flow from MRC, we call it Mask Data Correctness Check (MDCC). The mask house does MRC only to identify process limitations including writing, etching, metrology, etc. There still exist many potential errors that could occur when the frame, main circuit and dummies all together form a whole reticle. The MDCC flow combines the design rule check (DRC) and MRC concepts to adapt to the complex patterns in today's wafer production technologies. Although photomask data has unique characteristics, the MRC tool in Calibre® MDP can easily achieve mask composition by using the Extended MEBES job deck (EJB) format. In EJB format, we can customize the combination of any input layers in an IC design layout format, such as OASIS. Calibre MDP provides section-based processing for many standard verification rule format (SVRF) commands that support DRC-like checks on mask data. Integrating DRC-like checking with EJB for layer composition, we actually perform reticle-level DRC, which is the essence of MDCC. The flow also provides an early review environment before the photomask pattern files are available. Furthermore, to incorporate the MDCC in our production flow, runtime is one of the most important indexes we consider. When the MDCC is included in the tape-out flow, the runtime impact is very limited. Calibre, with its multi-threaded processes and good scalability, is the key to achieving acceptable runtime. In this paper, we present real case runtime data for 28nm and 14nm technology nodes, and prove the practicability of placing MDCC into mass production.

  20. Imaging with Synthetic Aperture Radar

    CERN Document Server

    Massonnet, Didier


    Describing a field that has been transformed by the recent availability of data from a new generation of space and airborne systems, the authors offer a synthetic geometrical approach to the description of synthetic aperture radar, one that addresses physicists, radar specialists, as well as experts in image processing.  

  1. Optimizing Synthetic Aperture Compound Imaging

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Jensen, Jørgen Arendt


    Spatial compound images are constructed from synthetic aperture data acquired using a linear phased-array transducer. Compound images of wires, tissue, and cysts are created using a method, which allows both transmit and receive compounding without any loss in temporal resolution. Similarly to co...

  2. Ultrasound fields from triangular apertures

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt


    The pulsed field from a triangular aperture mounted in an infinite, rigidbaffle is calculated. The approach of spatial impulse responses,as developed by Tupholme and Stepanishen, is used. By this both the emitted and received pulsed ultrasound field can be found for any transducerexcitation...

  3. Synthetic Aperture Radar - Hardware Development

    Directory of Open Access Journals (Sweden)

    V. Rosner


    Full Text Available Experimental real and synthetic aperture radar are developed from the base-band digital unit to the analogue RF parts, based on solid state units, using pulse compression for radar imaging. Proper QPSK code is found for matched filter.

  4. Stop-flow Lithography to Continuously Fabricate Microlens Structures Utilizing an Adjustable Three-Dimensional Mask

    Directory of Open Access Journals (Sweden)

    Shih-Hao Huang


    Full Text Available Stop-flow lithography (SFL is a microfluidic-based particle synthesis method, in which photolithography with a two dimensional (2D photomask is performed in situ within a microfluidic environment to fabricate multifunctional microstructures. Here, we modified the SFL technique by utilizing an adjustable electrostatic-force-modulated 3D (EFM-3D mask to continuously fabricate microlens structures for high-throughput production. The adjustable EFM-3D mask contains a layer filled with a UV-absorbing liquid and transparent elastomer structures in the shape of microlenses between two conductive glass substrates. An acrylate oligomer stream is photopolymerized via the microscope projection photolithography, where the EFM-3D mask was set at the field-stop plane of the microscope, thus forming the microlens structures. The produced microlens structures flow downstream without adhesion to the polydimethysiloxane (PDMS microchannel surfaces due to the existence of an oxygen-aided inhibition layer. Microlens structures with variations in curvature and aperture can be produced by changing objective magnifications, controlling the morphology of the EFM-3D mask through electrostatic force, and varying the concentration of UV-light absorption dyes. We have successfully demonstrated to produce microlens structures with an aperture ranging from 50 μm to 2 mm and the smallest focus spot size of 0.59 μm. Our proposed method allows one to fabricate microlens structures in a fast, simple and high-throughput mode for application in micro-optical systems.

  5. Masked hypertension in diabetes mellitus

    DEFF Research Database (Denmark)

    Franklin, Stanley S; Thijs, Lutgarde; Li, Yan


    Although distinguishing features of masked hypertension in diabetics are well known, the significance of antihypertensive treatment on clinical practice decisions has not been fully explored. We analyzed 9691 subjects from the population-based 11-country International Database on Ambulatory Blood...

  6. Bibliography of spatial interferometry in optical astronomy (United States)

    Gezari, Daniel Y.; Roddier, Francois; Roddier, Claude


    The Bibliography of Spatial Interferometry in Optical Astronomy is a guide to the published literature in applications of spatial interferometry techniques to astronomical observations, theory and instrumentation at visible and infrared wavelengths. The key words spatial and optical define the scope of this discipline, distinguishing it from spatial interferometry at radio wavelengths, interferometry in the frequency domain applied to spectroscopy, or more general electro-optics theoretical and laboratory research. The main bibliography is a listing of all technical articles published in the international scientific literature and presented at the major international meetings and workshops attended by the spatial interferometry community. Section B summarizes publications dealing with the basic theoretical concepts and algorithms proposed and applied to optical spatial interferometry and imaging through a turbulent atmosphere. The section on experimental techniques is divided into twelve categories, representing the most clearly identified major areas of experimental research work. Section D, Observations, identifies publications dealing specifically with observations of astronomical sources, in which optical spatial interferometry techniques have been applied.

  7. "The Mask Who Wasn't There": Visual Masking Effect with the Perceptual Absence of the Mask (United States)

    Rey, Amandine Eve; Riou, Benoit; Muller, Dominique; Dabic, Stéphanie; Versace, Rémy


    Does a visual mask need to be perceptually present to disrupt processing? In the present research, we proposed to explore the link between perceptual and memory mechanisms by demonstrating that a typical sensory phenomenon (visual masking) can be replicated at a memory level. Experiment 1 highlighted an interference effect of a visual mask on the…

  8. High Annular Resolution Stellar Interferometry. (United States)


    2. Note that or no aperture integra- proportionality have been omitted from Eq., 7. and h tion i.e.. D -; = 1) the -7,6 po6 oer Law is obe_ ed: it...the aoer~ure. . - is t-. tcc . _1sr ,ran tme acer:ure. The at-ttzci:ucs. nrugout --he analysis. two important assumptions wili se -7 t .hen

  9. Measurement of absolute optical thickness of mask glass by wavelength-tuning Fourier analysis. (United States)

    Kim, Yangjin; Hbino, Kenichi; Sugita, Naohiko; Mitsuishi, Mamoru


    Optical thickness is a fundamental characteristic of an optical component. A measurement method combining discrete Fourier-transform (DFT) analysis and a phase-shifting technique gives an appropriate value for the absolute optical thickness of a transparent plate. However, there is a systematic error caused by the nonlinearity of the phase-shifting technique. In this research the absolute optical-thickness distribution of mask blank glass was measured using DFT and wavelength-tuning Fizeau interferometry without using sensitive phase-shifting techniques. The error occurring during the DFT analysis was compensated for by using the unwrapping correlation. The experimental results indicated that the absolute optical thickness of mask glass was measured with an accuracy of 5 nm.

  10. The co-phasing detection method for sparse optical synthetic aperture systems

    Institute of Scientific and Technical Information of China (English)

    Liu Zheng; Wang Sheng-Qian; Rao Chang-Hui


    Co-phasing between different sub-apertures is important for sparse optical synthetic aperture telescope systems to achieve high-resolution imaging.For co-phasing detection in such a system,a new aspect of the system's far-field interferometry is analysed and used to construct a novel method to detect piston errors.An optical setup is built to demonstrate the efficacy of this method.Experimental results show that the relative differences between measurements by this method and the criterion are less than 4%,and their residual detecting errors are about 0.01 λ for different piston errors,which makes the use of co-phasing detection within such a system promising.

  11. High sensitivity moiré interferometry with compact achromatic interferometry (United States)

    Czarnek, Robert

    Experimental observations and measurements are the sources of information essential for correct development of mathematical models of real structural materials. Moiré interferometry offers high sensitivity in full-field measurements of in-plane displacements on the surface of a specimen. Although it is a powerful method in experimental stress analysis, it has some shortcomings. One is that existing systems require highly coherent light. The only sufficient source of light for this application is a long cavity laser, which is relatively expensive and at best cumbersome. Another shortcoming is that measurements must be performed in a vibration-free environment, such as that found on a holographic table. These requirements limit the use of existing moiré interferometers to a holographic laboratory. In this paper a modified concept of compensation is presented, which permits the use of a chromatic source of light in a compact moiré system. The compensator provides order in the angles of incident light for each separate wavelength, so that the virtual reference grating created by each wavelength in a continuous spectrum is identical in frequency and spatial position. The result is a virtual reference grating that behaves exactly like that created in coherent light. With this development the use of a laser diode, which is a non-coherent light source of tiny dimensions, becomes practical. The special configuration of the optics that create the virtual grating allows its synchronization with the specimen grating and leads to an interferometer design that is relatively insensitive to the vibrations found in a mechanical testing laboratory. Sensitivity to relative motion is analyzed theoretically. This development provides the oppurtunity to apply moiré interferometry to solid mechanics problems that cannot be studied in an optics laboratory. Experimental verification of the optical concepts is provided. A compact moiré interferometer based on the presented idea was

  12. Coherence Studies for Synthetic Aperture Sonar (United States)


    TITLE AND SUBTITLE Coherence Studies for Synthetic Aperture Sonar 5a. CONTRACT NUMBER 5b. GRANT NUMBER N00014-13-1-0020 5c. PROGRAM...systematic look at, coherence. 15. SUBJECT TERMS Synthetic; Aperture Sonar , Coherence, Seafloor Scatter, Propagation Variability 16. SECURITY...reconstruction of the document. Coherence Studies for Synthetic Aperture Sonar Anthony P. Lyons The Pennsylvania State University Applied Research

  13. Mask qualification strategies in a wafer fab (United States)

    Jaehnert, Carmen; Kunowski, Angela


    Having consistent high quality photo masks is one of the key factors in lithography in the wafer fab. Combined with stable exposure- and resist processes, it ensures yield increases in production and fast learning cycles for technology development and design evaluation. Preventive controlling of incoming masks and quality monitoring while using the mask in production is essential for the fab to avoid yield loss or technical problems caused by mask issues, which eventually result in delivery problems to the customer. In this paper an overview of the procedures used for mask qualification and production release, for both logic and DRAM, at Infineon Dresden is presented. Incoming qualification procedures, such as specification checks, incoming inspection, and inline litho process window evaluation, are described here. Pinching and electrical tests, including compatibility tests for mask copies for high volume products on optimized litho processes, are also explained. To avoid mask degradation over lifetime, re-inspection checks are done for re-qualification while using the mask in production. The necessity of mask incoming inspection and re-qualification, due to the repeater printing from either the processing defects of the original mask or degrading defects of being used in the fab (i.e. haze, ESD, and moving particles, etc.), is demonstrated. The need and impact of tight mask specifications, such as CD uniformity signatures and corresponding electrical results, are shown with examples of mask-wafer CD correlation.

  14. 21 CFR 868.5580 - Oxygen mask. (United States)


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  15. Parasitic interference in nulling interferometry

    CERN Document Server

    Matter, Alexis; Danchi, William C; Lopez, Bruno; Absil, Olivier


    Nulling interferometry aims to detect faint objects close to bright stars. Its principle is to produce a destructive interference along the line-of-sight so that the stellar flux is rejected, while the flux of the off-axis source can be transmitted. In practice, various instrumental perturbations can degrade the nulling performance. Any imperfection in phase, amplitude, or polarization produces a spurious flux that leaks to the interferometer output and corrupts the transmitted off-axis flux. One of these instrumental pertubations is the crosstalk phenomenon, which occurs because of multiple parasitic reflections inside transmitting optics, and/or diffraction effects related to beam propagation along finite size optics. It can include a crosstalk of a beam with itself, and a mutual crosstalk between different beams. This can create a parasitic interference pattern, which degrades the intrinsic transmission map - or intensity response - of the interferometer. In this context, we describe how this instrumental ...

  16. Moire interferometry with increased sensitivity (United States)

    Han, Bongtae; Post, Daniel

    The basic sensitivity of moire interferometry was increased beyond the previously conceived theoretical limit. This was accomplished by creating the virtual reference grating inside a refractive medium instead of air, thus shortening the wavelength of light. A very compact four-beam moire interferometer in a refractive medium was developed for microscopic viewing, which produced a basic sensitivity of 208 nm per fringe order, corresponding to moire with 4800 lines per mm. Its configuration made it inherently stable and relatively insensitive to environmental disturbances. An optical microscope was employed as the image recording system to obtain high spatial resolution. The method was demonstrated for deformation of a thick graphite/epoxy composite at the 0/90 deg ply interface.

  17. Binary Cepheids from optical interferometry

    CERN Document Server

    Gallenne, A; Mérand, A; Monnier, J D; Pietrzyński, J Breitfelder G; Gieren, W


    Classical Cepheid stars have been considered since more than a century as reliable tools to estimate distances in the universe thanks to their Period-Luminosity (P-L) relationship. Moreover, they are also powerful astrophysical laboratories, providing fundamental clues for studying the pulsation and evolution of intermediate-mass stars. When in binary systems, we can investigate the age and evolution of the Cepheid, estimate the mass and distance, and constrain theoretical models. However, most of the companions are located too close to the Cepheid (1-40 mas) to be spatially resolved with a 10-meter class telescope. The only way to spatially resolve such systems is to use long-baseline interferometry. Recently, we have started a unique and long-term interferometric program that aims at detecting and characterizing physical parameters of the Cepheid companions, with as main objectives the determination of accurate masses and geometric distances.

  18. Broadband synthetic aperture geoacoustic inversion. (United States)

    Tan, Bien Aik; Gerstoft, Peter; Yardim, Caglar; Hodgkiss, William S


    A typical geoacoustic inversion procedure involves powerful source transmissions received on a large-aperture receiver array. A more practical approach is to use a single moving source and/or receiver in a low signal to noise ratio (SNR) setting. This paper uses single-receiver, broadband, frequency coherent matched-field inversion and exploits coherently repeated transmissions to improve estimation of the geoacoustic parameters. The long observation time creates a synthetic aperture due to relative source-receiver motion. This approach is illustrated by studying the transmission of multiple linear frequency modulated (LFM) pulses which results in a multi-tonal comb spectrum that is Doppler sensitive. To correlate well with the measured field across a receiver trajectory and to incorporate transmission from a source trajectory, waveguide Doppler and normal mode theory is applied. The method is demonstrated with low SNR, 100-900 Hz LFM pulse data from the Shallow Water 2006 experiment.

  19. Computational mask defect review for contamination and haze inspections (United States)

    Morgan, Paul; Rost, Daniel; Price, Daniel; Corcoran, Noel; Satake, Masaki; Hu, Peter; Peng, Danping; Yonenaga, Dean; Tolani, Vikram; Wolf, Yulian; Shah, Pinkesh


    As optical lithography continues to extend into sub-0.35 k1 regime, mask defect inspection and subsequent review has become tremendously challenging, and indeed the largest component to mask manufacturing cost. The routine use of various resolution enhancement techniques (RET) have resulted in complex mask patterns, which together with the need to detect even smaller defects due to higher MEEFs, now requires an inspection engineer to use combination of inspection modes. This is achieved in 193nm AeraTM mask inspection systems wherein masks are not only inspected at their scanner equivalent aerial exposure conditions, but also at higher Numerical Aperture resolution, and special reflected-light, and single-die contamination modes, providing better coverage over all available patterns, and defect types. Once the required defects are detected by the inspection system, comprehensively reviewing and dispositioning each defect then becomes the Achilles heel of the overall mask inspection process. Traditionally, defects have been reviewed manually by an operator, which makes the process error-prone especially given the low-contrast in the convoluted aerial images. Such manual review also limits the quality and quantity of classifications in terms of the different types of characterization and number of defects that can practically be reviewed by a person. In some ways, such manual classification limits the capability of the inspection tool itself from being setup to detect smaller defects since it often results in many more defects that need to be then manually reviewed. Paper 8681-109 at SPIE Advanced Lithography 2013 discussed an innovative approach to actinic mask defect review using computational technology, and focused on Die-to-Die transmitted aerial and high-resolution inspections. In this approach, every defect is characterized in two different ways, viz., quantitatively in terms of its print impact on wafer, and qualitatively in terms of its nature and origin in

  20. Some applications of holographic interferometry in biomechanics (United States)

    Ebbeni, Jean P. L.


    Holographic interferometry is well adapted for the determination of 2D strain fields in osseous structures. The knowledge of those strain fields is important for the understanding of structure behavior such as arthrosis.

  1. Fundamental physics research and neutron interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Ioffe, A. [Hahn-Meitner-Institut Berlin GmbH (Germany)


    The possibility of the use of an extremely sensitive neutron interferometry technique for the study of electromagnetic structure of the neutron and the parity non-conservative effects in neutron spin rotation is discussed. (author)

  2. Novel Polarimetric SAR Interferometry Algorithms Project (United States)

    National Aeronautics and Space Administration — Polarimetric radar interferometry (PolInSAR) is a new SAR imaging mode that is rapidly becoming an important technique for bare earth topographic mapping, tree...

  3. Extra Solar Planet Science With a Non Redundant Mask (United States)

    Minto, Stefenie Nicolet; Sivaramakrishnan, Anand; Greenbaum, Alexandra; St. Laurent, Kathryn; Thatte, Deeparshi


    To detect faint planetary companions near a much brighter star, at the Resolution Limit of the James Webb Space Telescope (JWST) the Near-Infrared Imager and Slitless Spectrograph (NIRISS) will use a non-redundant aperture mask (NRM) for high contrast imaging. I simulated NIRISS data of stars with and without planets, and run these through the code that measures interferometric image properties to determine how sensitive planetary detection is to our knowledge of instrumental parameters, starting with the pixel scale. I measured the position angle, distance, and contrast ratio of the planet (with respect to the star) to characterize the binary pair. To organize this data I am creating programs that will automatically and systematically explore multi-dimensional instrument parameter spaces and binary characteristics. In the future my code will also be applied to explore any other parameters we can simulate.

  4. JERS-1 Synthetic Aperture Radar Interferometry Applications: Mapping of Rain Forest Environments and Crustal Deformation Studies (United States)

    Rosen, P.; Hensley, S.; Peltzer, G.; Rignot, E.; Werner, C.


    This research using JERS-1 SAR data has been very fruitful, resulting in a strong collaboration with geodesists and geophysicists in Japan, and several important papers characterizing crustal deformation, and the capabilities and limitations of JERS data for these studies.

  5. Fringe formation in dual-hologram interferometry (United States)

    Burner, A. W.


    Reference-fringe formation in nondiffuse dual-hologram interferometry is described by combining a first-order geometrical hologram treatment with interference fringes generated by two point sources. The first-order imaging relationships can be used to describe reference-fringe patterns for the geometry of the dual-hologram interferometry. The process can be completed without adjusting the two holograms when the reconstructing wavelength is less than the exposing wavelength, and the process is found to facilitate basic intereferometer adjustments.

  6. Reduction of batwing effect in white light interferometry for measurement of patterned sapphire substrates (PSS) wafer (United States)

    Tapilouw, Abraham Mario; Chang, Yi-Wei; Yu, Long-Yo; Wang, Hau-Wei


    Patterned sapphire substrates (PSS) wafers are used in LED manufacturing to enhance the luminous conversion of LED chips. The most critical characteristics in PSS wafers are height, width, pitch and shape of the pattern. The common way to measure these characteristics is by using surface electron microscope (SEM). White light interferometry is capable to measure dimension with nanometer accuracy and it is suitable for measuring the characteristics of PSS wafers. One of the difficulties in measuring PSS wafers is the aspect ratio and density of the features. The high aspect ratio combined with dense pattern spacing diffracts incoming lights and reduces the accuracy of the white light interferometry measurement. In this paper, a method to improve the capability of white light interferometry for measuring PSS wafers by choosing the appropriate wavelength and microscope objective with high numerical aperture. The technique is proven to be effective for reducing the batwing effect in edges of the feature and improves measurement accuracy for PSS wafers with circular features of 1.95 um in height and diameters, and 700 nm spacing between the features. Repeatability of the measurement is up to 5 nm for height measurement and 20 nm for pitch measurement.

  7. Topographic Phase Recovery from Stacked ERS Interferometry and a Low-Resolution Digital Elevation Model (United States)

    Sandwell, David T.; Sichoix, Lydie; Frey, Herbert V. (Technical Monitor)


    A hybrid approach to topographic recovery from ERS interferometry is developed and assessed. Tropospheric/ionospheric artifacts, imprecise orbital information, and layover are key issues in recovering topography and surface deformation from repeat-pass interferometry. Previously, we developed a phase gradient approach to stacking interferograms to reduce these errors and also to reduce the short-wavelength phase noise (see Sandwell arid Price [1998] and Appendix A). Here the method is extended to use a low-resolution digital elevation model to constrain long-wavelength phase errors and an iteration scheme to minimize errors in the computation of phase gradient. We demonstrate the topographic phase recovery on 16-m postings using 25 ERS synthetic aperture radar images from an area of southern California containing 2700 m of relief. On the basis of a comparison with 81 GPS monuments, the ERS derived topography has a typical absolute accuracy of better than 10 m except in areas of layover. The resulting topographic phase enables accurate two-pass, real-time interferometry even in mountainous areas where traditional phase unwrapping schemes fail. As an example, we form a topography-free (127-m perpendicular baseline) interferogram spanning 7.5 years; fringes from two major earthquakes and a seismic slip on the San Andreas Fault are clearly isolated.

  8. A Coded Aperture Compressive Imaging Array and Its Visual Detection and Tracking Algorithms for Surveillance Systems

    Directory of Open Access Journals (Sweden)

    Hanxiao Wu


    Full Text Available In this paper, we propose an application of a compressive imaging system to the problem of wide-area video surveillance systems. A parallel coded aperture compressive imaging system is proposed to reduce the needed high resolution coded mask requirements and facilitate the storage of the projection matrix. Random Gaussian, Toeplitz and binary phase coded masks are utilized to obtain the compressive sensing images. The corresponding motion targets detection and tracking algorithms directly using the compressive sampling images are developed. A mixture of Gaussian distribution is applied in the compressive image space to model the background image and for foreground detection. For each motion target in the compressive sampling domain, a compressive feature dictionary spanned by target templates and noises templates is sparsely represented. An l1 optimization algorithm is used to solve the sparse coefficient of templates. Experimental results demonstrate that low dimensional compressed imaging representation is sufficient to determine spatial motion targets. Compared with the random Gaussian and Toeplitz phase mask, motion detection algorithms using a random binary phase mask can yield better detection results. However using random Gaussian and Toeplitz phase mask can achieve high resolution reconstructed image. Our tracking algorithm can achieve a real time speed that is up to 10 times faster than that of the l1 tracker without any optimization.

  9. Shadows alter facial expressions of Noh masks.

    Directory of Open Access Journals (Sweden)

    Nobuyuki Kawai

    Full Text Available BACKGROUND: A Noh mask, worn by expert actors during performance on the Japanese traditional Noh drama, conveys various emotional expressions despite its fixed physical properties. How does the mask change its expressions? Shadows change subtly during the actual Noh drama, which plays a key role in creating elusive artistic enchantment. We here describe evidence from two experiments regarding how attached shadows of the Noh masks influence the observers' recognition of the emotional expressions. METHODOLOGY/PRINCIPAL FINDINGS: In Experiment 1, neutral-faced Noh masks having the attached shadows of the happy/sad masks were recognized as bearing happy/sad expressions, respectively. This was true for all four types of masks each of which represented a character differing in sex and age, even though the original characteristics of the masks also greatly influenced the evaluation of emotions. Experiment 2 further revealed that frontal Noh mask images having shadows of upward/downward tilted masks were evaluated as sad/happy, respectively. This was consistent with outcomes from preceding studies using actually tilted Noh mask images. CONCLUSIONS/SIGNIFICANCE: Results from the two experiments concur that purely manipulating attached shadows of the different types of Noh masks significantly alters the emotion recognition. These findings go in line with the mysterious facial expressions observed in Western paintings, such as the elusive qualities of Mona Lisa's smile. They also agree with the aesthetic principle of Japanese traditional art "yugen (profound grace and subtlety", which highly appreciates subtle emotional expressions in the darkness.

  10. Spatial release from informational masking (United States)

    Rakerd, Brad; Aaronson, Neil L.


    A new method for investigating spatial release from informational masking was developed and employed in two experiments. The new method is computer controlled and efficient. It employs the versatile coordinate response measure speech stimulus set [Bolia et al., J. Acoust. Soc. Am. 107, 1065 (2000)]. The experiments were conducted in an anechoic room, with a primary loudspeaker in front of the listener and a secondary loudspeaker at 60 deg to the right. Target messages were presented from the primary speaker only. For a standard, distractor messages, simultaneous with the target, were also presented from the primary speaker only. Spatial release was measured by presenting the distractors from both primary and secondary speakers with a temporal offset. Experiment 1 fixed the offset (secondary leading, +4 ms) and varied the number of distractors (1 to 3) and the target-to-distractor ratio (-12 to +4 dB). Masking release, sometimes as large as 10 dB, was found for all combinations of these variables. Experiment 2 varied the offset over a wide range of values. Substantial release from masking was found for both positive and negative offsets, but only in the range in which speech echoes are suppressed (<50 ms). [Work supported by NIDCD grant DC 00181.

  11. Event Localization in Bulk Scintillator Crystals Using Coded Apertures

    Energy Technology Data Exchange (ETDEWEB)

    Ziock, Klaus-Peter [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Braverman, Joshua B. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Fabris, Lorenzo [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Harrison, Mark J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hornback, Donald Eric [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Newby, Jason [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)


    The localization of radiation interactions in bulk scintillators is generally limited by the size of the light distribution at the readout surface of the crystal/light-pipe system. By finding the centroid of the light spot, which is typically of order centimeters across, practical single-event localization is limited to ~2 mm/cm of crystal thickness. Similar resolution can also be achieved for the depth of interaction by measuring the size of the light spot. Through the use of near-field coded-aperture techniques applied to the scintillation light, light transport simulations show that for 3-cm-thick crystals, more than a five-fold improvement (millimeter spatial resolution) can be achieved both laterally and in event depth. At the core of the technique is the requirement to resolve the shadow from an optical mask placed in the scintillation light path between the crystal and the readout. In this paper, experimental results are presented that demonstrate the overall concept using a 1D shadow mask, a thin-scintillator crystal and a light pipe of varying thickness to emulate a 2.2-cm-thick crystal. Spatial resolutions of ~ 1 mm in both depth and transverse to the readout face are obtained over most of the crystal depth.

  12. Super Unit Cells in Aperture-Based Metamaterials

    Directory of Open Access Journals (Sweden)

    Dragan Tanasković


    Full Text Available An important class of electromagnetic metamaterials are aperture-based metasurfaces. Examples include extraordinary optical transmission arrays and double fishnets with negative refractive index. We analyze a generalization of such metamaterials where a simple aperture is now replaced by a compound object formed by superposition of two or more primitive objects (e.g., rectangles, circles, and ellipses. Thus obtained “super unit cell” shows far richer behavior than the subobjects that comprise it. We show that nonlocalities introduced by overlapping simple subobjects can be used to produce large deviations of spectral dispersion even for small additive modifications of the basic geometry. Technologically, some super cells may be fabricated by simple spatial shifting of the existing photolithographic masks. In our investigation we applied analytical calculations and ab initio finite element modeling to prove the possibility to tailor the dispersion including resonances for plasmonic nanocomposites by adjusting the local geometry and exploiting localized interactions at a subwavelength level. Any desired form could be defined using simple primitive objects, making the situation a geometrical analog of the case of series expansion of a function. Thus an additional degree of tunability of metamaterials is obtained. The obtained designer structures can be applied in different fields like waveguiding and sensing.

  13. High performance mask fabrication process for the next-generation mask production (United States)

    Yagawa, Keisuke; Ugajin, Kunihiro; Suenaga, Machiko; Kobayashi, Yoshihito; Motokawa, Takeharu; Hagihara, Kazuki; Saito, Masato; Itoh, Masamitsu


    ArF immersion lithography combined with double patterning has been used for fabricating below half pitch 40nm devices. However, when pattern size shrinks below 20nm, we must use new technology like quadruple patterning process or next generation lithography (NGL) solutions. Moreover, with change in lithography tool, next generation mask production will be needed. According to ITRS 2013, fabrication of finer patterns less than 15nm will be required on mask plate in NGL mask production 5 years later [1]. In order to fabricate finer patterns on mask, higher resolution EB mask writer and high performance fabrication process will be required. In a previous study, we investigated a potential of mask fabrication process for finer patterning and achieved 17nm dense line pattern on mask plate by using VSB (Variable Shaped Beam) type EB mask writer and chemically amplified resist [2][3]. After a further investigation, we constructed higher performance mask process by using new EB mask writer EBM9000. EBM9000 is the equipment supporting hp16nm generation's photomask production and has high accuracy and high throughput. As a result, we achieved 15.5nm pattern on mask with high productivity. Moreover, from evaluation of isolated pattern, we proved that current mask process has the capability for sub-10nm pattern. These results show that the performance of current mask fabrication process have the potential to fabricate the next-generation mask.

  14. Structural colour printing from a reusable generic nanosubstrate masked for the target image (United States)

    Rezaei, M.; Jiang, H.; Kaminska, B.


    Structural colour printing has advantages over traditional pigment-based colour printing. However, the high fabrication cost has hindered its applications in printing large-area images because each image requires patterning structural pixels in nanoscale resolution. In this work, we present a novel strategy to print structural colour images from a pixelated substrate which is called a nanosubstrate. The nanosubstrate is fabricated only once using nanofabrication tools and can be reused for printing a large quantity of structural colour images. It contains closely packed arrays of nanostructures from which red, green, blue and infrared structural pixels can be imprinted. To print a target colour image, the nanosubstrate is first covered with a mask layer to block all the structural pixels. The mask layer is subsequently patterned according to the target colour image to make apertures of controllable sizes on top of the wanted primary colour pixels. The masked nanosubstrate is then used as a stamp to imprint the colour image onto a separate substrate surface using nanoimprint lithography. Different visual colours are achieved by properly mixing the red, green and blue primary colours into appropriate ratios controlled by the aperture sizes on the patterned mask layer. Such a strategy significantly reduces the cost and complexity of printing a structural colour image from lengthy nanoscale patterning into high throughput micro-patterning and makes it possible to apply structural colour printing in personalized security features and data storage. In this paper, nanocone array grating pixels were used as the structural pixels and the nanosubstrate contains structures to imprint the nanocone arrays. Laser lithography was implemented to pattern the mask layer with submicron resolution. The optical properties of the nanocone array gratings are studied in detail. Multiple printed structural colour images with embedded covert information are demonstrated.

  15. Aperture scanning Fourier ptychographic microscopy (United States)

    Ou, Xiaoze; Chung, Jaebum; Horstmeyer, Roarke; Yang, Changhuei


    Fourier ptychographic microscopy (FPM) is implemented through aperture scanning by an LCOS spatial light modulator at the back focal plane of the objective lens. This FPM configuration enables the capturing of the complex scattered field for a 3D sample both in the transmissive mode and the reflective mode. We further show that by combining with the compressive sensing theory, the reconstructed 2D complex scattered field can be used to recover the 3D sample scattering density. This implementation expands the scope of application for FPM and can be beneficial for areas such as tissue imaging and wafer inspection. PMID:27570705

  16. Space noise synthetic aperture radar (United States)

    Kulpa, Krzysztof S.


    The paper presents limitations of space borne synthetic aperture radars, caused by range and Doppler velocity ambiguities, and the concept of usage of the noise radar technology for creation of high-resolution space SAR images. The noise SAR is free from limitation caused by the periodicity of pulse waveform ambiguity function, and therefore this technology can be used in the future space missions. The basic concept of noise SAR image formation is also presented. The image formation algorithm has been verified using the simulated data produced by Raw Radar Data Simulator.

  17. Novel dispersion tolerant interferometry method for accurate measurements of displacement (United States)

    Bradu, Adrian; Maria, Michael; Leick, Lasse; Podoleanu, Adrian G.


    We demonstrate that the recently proposed master-slave interferometry method is able to provide true dispersion free depth profiles in a spectrometer-based set-up that can be used for accurate displacement measurements in sensing and optical coherence tomography. The proposed technique is based on correlating the channelled spectra produced by the linear camera in the spectrometer with previously recorded masks. As such technique is not based on Fourier transformations (FT), it does not require any resampling of data and is immune to any amounts of dispersion left unbalanced in the system. In order to prove the tolerance of technique to dispersion, different lengths of optical fiber are used in the interferometer to introduce dispersion and it is demonstrated that neither the sensitivity profile versus optical path difference (OPD) nor the depth resolution are affected. In opposition, it is shown that the classical FT based methods using calibrated data provide less accurate optical path length measurements and exhibit a quicker decays of sensitivity with OPD.

  18. Theoretical study on optical storage of the transmitted-aperture type super-RENS (United States)

    Shen, Quanhong; Xu, Duanyi; Ma, Jianshe; Liu, Rong; Qi, Guosheng


    In this paper, theoretical work on the transmitted-aperture (TA) type super-RENS was introduced. Firstly, the forming of transmitted-aperture in the mask layer was studied based on laser-induced thermal model with Gauss assumption. A numerical simulation was carried out by FEMLAB. The simulation results showed that transmitted aperture would not be formed until the exposure power exceeded a threshold within a certain pulse time and vice versa. Secondly, a calculation model of electromagnetic field of TA type super-RENS disk was presented based on the three-dimensional finite-difference time-domain method (3D-FDTD) together with a vector method of Gaussian beam. Lorenz dispersive model was employed for mask layer and reflective layer. The distributions of electric field for TA type super-RENS were theoretically analyzed. Lastly, the static writing experiment for TA type Super-RENS was carried out with different power and pulse time, as well as for conventional CD-R/W. The experiment results well satisfied the simulation.

  19. SAMSI: An orbiting spatial interferometer for micro-arc second astronomical observations. [Spacecraft Array for Michelson Spatial Interferometry (SAMSI) (United States)

    Stachnik, R. V.; Gezari, D. Y.


    The concept and performance of (SAMSI) Spacecraft Array for Michelson Spatial Interferometry, an orbiting spatial interferometer comprised of three free-flying spacecraft, two collector telescopes and a central mixing station are described. In the one-dimensional interferometry mode orbits exist which provide natural scanning of the baseline. These orbits place extremely small demands on thrusters and fuel consumption. Resolution of 0.00001 arcsecond and magnitude limits of mv = 15 to 20 are achievable in a single orbit. In the imaging mode, SAMSI could synthesize images equivalent to those produced by equal diameter filled apertures in space, making use of the fuel resupply capability of a space station. Simulations indicate that image reconstruction can be performed with milliarcsecond resolution to a visual magnitude 12 in 12 hr of spiral scanning integration time.

  20. Updated progress in theories and applications of spaceborne SAR interferometry (United States)

    Chen, Yan-Ling; Huang, Cheng; Ding, Xiao-Li; Li, Zhi-Wei


    InSAR (Interferometric Synthetic Aperture Radar) and D-InSAR (Differential InSAR) are rapidly developed new technologies of space geodesy during the late 20th century, and now obviously become hot research topics in the field of microwave remote sensing. Compared with the other sensors, InSAR possesses many incomparable advantages such as the capability to work at all-time and under all weather, very high spatial resolution and strong penetrability through the ground surface. This paper introduces general status of SAR, InSAR, D-InSAR technology, and the principles of InSAR and D-InSAR. New theories and the potential problems of (D-)InSAR technology are largely discussed, including multi-baseline interferometry, Pol-InSAR technique, the correction of atmospheric effects, permanent Scatterers method, the synthesization technique between InSAR and GPS, LIDAR etc., and the InSAR parallel algorithm. Then the new applications of InSAR and D-InSAR are described in detail including 3D topographic mapping, deformation monitoring (including surface subsidence, landside monitoring and ITRF's foundation and maintenance, etc.), thematic mapping (including agriculture and forestry, oceanic surveying and flood monitoring, etc.) and meteorology etc.. Finally, the prospect and future trends in InSAR development are summarized.

  1. Fourier domain multispectral multiple scattering low coherence interferometry. (United States)

    Matthews, Thomas E; Giacomelli, Michael G; Brown, William J; Wax, Adam


    We have implemented multispectral multiple scattering low coherence interferometry (ms2/LCI) with Fourier domain data collection. The ms2/LCI system is designed to localize features with spectroscopic contrast with millimeter resolution up to 1 cm deep in scattering samples by using photons that have undergone multiple low-angle (forward) scattering events. Fourier domain detection both increases the data acquisition speed of the system and gives access to rich spectroscopic information, compared to the previous single channel, time-domain implementation. Separate delivery and detection angular apertures reduce collection of the diffuse background signal in order to isolate localized spectral features from deeper in scattering samples than would be possible with traditional spectroscopic optical coherence tomography. Light from a supercontinuum source is used to acquire absorption spectra of chromophores in the visible range within a tissue-like scattering phantom. An intensity modulation and digital lock-in detection scheme is implemented to mitigate relative intensity and spectral noise inherent in supercontinuum sources. The technical parameters of the system and comparative analysis are presented.

  2. Dynamic measurement of deformation using Fourier transform digital holographic interferometry (United States)

    Gao, Xinya; Wu, Sijin; Yang, Lianxiang


    Digital holographic interferometry (DHI) is a well-established optical technique for measurement of nano-scale deformations. It has become more and more important due to the rapid development of applications in aerospace engineering and biomedicine. Traditionally, phase shift technique is used to quantitatively measure the deformations in DHI. However, it cannot be applied in dynamic measurement. Fourier transform phase extraction method, which can determine the phase distribution from only a single hologram, becomes a promising method to extract transient phases in DHI. This paper introduces a digital holographic interferometric system based on 2D Fourier transform phase extraction method, with which deformations of objects can be measured quickly. In the optical setup, the object beam strikes a CCD via a lens and aperture, and the reference beam is projected on the CCD through a single-mode fiber. A small inclination angle between the diverging reference beam and optical axial is introduced in order to physically separate the Fourier components in frequency domain. Phase maps are then obtained by the utilization of Fourier transform and windowed inverse Fourier transform. The capability of the Fourier transform DHI is discussed by theoretical discussion as well as experiments.

  3. Atmospheric Turbulence Compensation with Laser Phase Shifting Interferometry

    CERN Document Server

    Rabien, S; Genzel, R; Davies, R I; Ott, T


    Laser guide stars with adaptive optics allow astronomical image correction in the absence of a natural guide star. Single guide star systems with a star created in the earth's sodium layer can be used to correct the wavefront in the near infrared spectral regime for 8-m class telescopes. For possible future telescopes of larger sizes, or for correction at shorter wavelengths, the use of a single guide star is ultimately limited by focal anisoplanatism that arises from the finite height of the guide star. To overcome this limitation we propose to overlap coherently pulsed laser beams that are expanded over the full aperture of the telescope, traveling upwards along the same path which light from the astronomical object travels downwards. Imaging the scattered light from the resultant interference pattern with a camera gated to a certain height above the telescope, and using phase shifting interferometry we have found a method to retrieve the local wavefront gradients. By sensing the backscattered light from tw...

  4. Earthquake Monitoring in Australia Using Satellite Radar Interferometry

    Institute of Scientific and Technical Information of China (English)

    Ge Lin-lin; E. Cheng; D. Polonska; C. Rizos; C. Collins; C. Smith


    Are there any earthquakes in Australia? Although most Australians are not as familiar with earthquakes as citizens in countries such as Japan, there are some quakes on the Australian continent every year. Differential Synthetic Aperture Radar Interferometry (DInSAR) has been widely used in recent years for monitoring crustal deformation due to earthquakes, volcanoes, underground mining, oil extraction,and so on. Hence the follow-on question is, can repeat-pass satellite DInSAR be used in Australian regions to monitor earthquakes? Nine ERS-1 and ERS-2 radar images of the Burakin region in Western Australia were used to form the InSAR pairs.Twenty-two InSAR pairs were formed and were used to study the temporal decorrelation characteristics in the Burakin area. It was found that good coherence could be maintained all over the full scene for a pair spanning 211 d. The repeat cycles of RADARSAT and ERS (all C-band SAR missions) are 24 and 35 drespectively, Furthermore it is easier to maintain good coherence in L-band SAR images (e.g. the JERS-1 mission has a 44 d repeat cycle). Therefore the authors are confident that repeat-pass differential InSAR can be used to monitor ground deformation due to earthquakes in the Burakin region.

  5. Parsimonious Refraction Interferometry and Tomography

    KAUST Repository

    Hanafy, Sherif


    We present parsimonious refraction interferometry and tomography where a densely populated refraction data set can be obtained from two reciprocal and several infill shot gathers. The assumptions are that the refraction arrivals are head waves, and a pair of reciprocal shot gathers and several infill shot gathers are recorded over the line of interest. Refraction traveltimes from these shot gathers are picked and spawned into O(N2) virtual refraction traveltimes generated by N virtual sources, where N is the number of geophones in the 2D survey. The virtual traveltimes can be inverted to give the velocity tomogram. This enormous increase in the number of traveltime picks and associated rays, compared to the many fewer traveltimes from the reciprocal and infill shot gathers, allows for increased model resolution and a better condition number with the system of normal equations. A significant benefit is that the parsimonious survey and the associated traveltime picking is far less time consuming than that for a standard refraction survey with a dense distribution of sources.

  6. Neutron interferometry with cold stage (United States)

    Mineeva, Taisiya; Arif, M.; Huber, M. G.; Shahi, C. B.; Clark, C. W.; Cory, D. G.; Nsofini, J.; Sarenac, D.; Pushin, D. A.

    Neutron interferometry (NI) is amongst the most precise methods for characterizing neutron interactions by measuring the relative difference between two neutron paths, one of which contains a sample-of-interest. Because neutrons carry magnetic moment and are deeply penetrating, they are excellent probes to investigate properties of magnetic materials. The advantage of NI is its unique sensitivity which allows to directly measure magnetic and structural transitions in materials. Up to now NI has been sparingly used in material research due to its sensitivity to environmental noise. However, recent successes in implementing Quantum Error Correction principles lead to an improved NI design making it robust against mechanical vibrations. Following these advances, a new user facility at the National Institute for Standards and Technology was built to study condensed matter applications, biology and quantum physics. Incorporating cold sample stage inside NI is the first of its kind experiment which can be carried out on large range of temperatures down to 4K. Upon successful realization, it will open new frontiers to characterize magnetic domains, phase transitions and spin properties in a variety of materials such as, for example, iron-based superconductors and spintronic materials. Supported in part by CERC, CIFAR, NSERC and CREATE.

  7. Aperture Effects on Spectroscopic Galaxy Activity Classification

    CERN Document Server

    Maragkoudakis, A; Ashby, M L N; Willner, S P


    Activity classification of galaxies based on long-slit and fiber spectroscopy can be strongly influenced by aperture effects. Here we investigate how activity classification for 14 nearby galaxies depends on the proportion of the host galaxy's light that is included in the aperture. We use both observed long-slit spectra and simulated elliptical-aperture spectra of different sizes. The degree of change varies with galaxy morphology and nuclear activity type. Starlight removal techniques can mitigate but not remove the effect of host galaxy contamination in the nuclear aperture. Galaxies with extra-nuclear star formation can show higher [O III] {\\lambda}5007/H{\\beta} ratios with increasing aperture, in contrast to the naive expectation that integrated light will only dilute the nuclear emission lines. We calculate the mean dispersion for the diagnostic line ratios used in the standard BPT diagrams with respect to the central aperture of spectral extraction to obtain an estimate of the uncertainties resulting f...

  8. The role of Fizeau interferometry in planetary science (United States)

    Conrad, Albert R.


    Historically, two types of interferometer have been used to the study of solar system objects: coaxial and Fizeau. While coaxial interferometers are well-suited to a wide range of galactic and extra-galactic science cases, solar system science cases are, in most cases, better carried out with Fizeau imagers. Targets of interest in our solar system are often bright and compact, and the science cases for these objects often call for a complete, or nearly complete, image at high angular resolution. For both methods, multiple images must be taken at varying baselines to reconstruct an image. However, with the Fizeau technique that number is far fewer than it is for the aperture synthesis method employed by co-axial interferometers. In our solar system, bodies rotate and their surfaces are sometimes changing over yearly, or even weekly, time scales. Thus, the need to be able to exploit the high angular resolution of an interferometer with only a handful of observations taken on a single night, as is the case for Fizeau interferometers, gives a key advantage to this technique. The aperture of the Large Binocular Telescope (LBT), two 8.4 circular mirrors separated center-to-center by 14.4 meters, is optimal for supporting Fizeau interferometry. The first of two Fizeau imagers planned for LBT, the LBT Interferometer (LBTI),1 saw first fringes in 2010 and has proven to be a valuable tool for solar system studies. Recent studies of Jupiters volcanic moon Io have yielded results that rely on the angular resolution provided by the full 23-meter baseline of LBT Future studies of the aurora at Jupiters poles and the shape and binarity of asteroids are planned. While many solar system studies can be carried out on-axis (i.e., using the target of interest as the beacon for both adaptive optics correction and fringe tracking), studies such as Io-in-eclipse, full disk of Jupiter and Mars, and binarity of Kuiper belt objects, require off-axis observations (i.e., using one or more

  9. Advanced Multiple Aperture Seeing Profiler (United States)

    Ren, Deqing; Zhao, Gang


    Measurements of the seeing profile of the atmospheric turbulence as a function of altitude are crucial for solar astronomical site characterization, as well as the optimized design and performance estimation of solar Multi-Conjugate Adaptive Optics (MCAO). Knowledge of the seeing distribution, up to 30 km, with a potential new solar observation site, is required for future solar MCAO developments. Current optical seeing profile measurement techniques are limited by the need to use a large facility solar telescope for such seeing profile measurements, which is a serious limitation on characterizing a site's seeing conditions in terms of the seeing profile. Based on our previous work, we propose a compact solar seeing profiler called the Advanced Multiple Aperture Seeing Profile (A-MASP). A-MASP consists of two small telescopes, each with a 100 mm aperture. The two small telescopes can be installed on a commercial computerized tripod to track solar granule structures for seeing profile measurement. A-MASP is extreme simple and portable, which makes it an ideal system to bring to a potential new site for seeing profile measurements.

  10. Directional synthetic aperture flow imaging

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav


    A method for flow estimation using synthetic aperture imaging and focusing along the flow direction is presented. The method can find the correct velocity magnitude for any flow angle and full color flow images can be measured using only 32 to 128 pulse emissions. The approach uses spherical wave...... artery and jugular vein of a healthy 29 years old volunteer was acquired. A full color flow image using only 128 emissions could be made with a high velocity precision.......A method for flow estimation using synthetic aperture imaging and focusing along the flow direction is presented. The method can find the correct velocity magnitude for any flow angle and full color flow images can be measured using only 32 to 128 pulse emissions. The approach uses spherical wave...... angle is manually determined from the B-mode image. The approach can be used for both tissue and blood velocity determination. The approach was investigated using both simulations and a flow system with a laminar flow. The flow profile was measured with a commercial 7.5 MHz linear array transducer...

  11. Advanced Optics Experiments Using Nonuniform Aperture Functions

    CERN Document Server

    Wood, Lowell T


    A method to create instructive, nonuniform aperture functions using spatial frequency filtering is described. The diffraction from a single slit in the Fresnel limit and the interference from a double slit in the Fraunhofer limit are spatially filtered to create electric field distributions across an aperture to produce apodization, inverse apodization or super-resolution, and apertures with phase shifts across their widths. The diffraction effects from these aperture functions are measured and calculated. The excellent agreement between the experimental results and the calculated results makes the experiment ideal for use in an advanced undergraduate or graduate optics laboratory to illustrate experimentally several effects in Fourier optics.

  12. Ion mobility spectrometer with virtual aperture grid (United States)

    Pfeifer, Kent B.; Rumpf, Arthur N.


    An ion mobility spectrometer does not require a physical aperture grid to prevent premature ion detector response. The last electrodes adjacent to the ion collector (typically the last four or five) have an electrode pitch that is less than the width of the ion swarm and each of the adjacent electrodes is connected to a source of free charge, thereby providing a virtual aperture grid at the end of the drift region that shields the ion collector from the mirror current of the approaching ion swarm. The virtual aperture grid is less complex in assembly and function and is less sensitive to vibrations than the physical aperture grid.

  13. Computational defect review for actinic mask inspections (United States)

    Morgan, Paul; Rost, Daniel; Price, Daniel; Corcoran, Noel; Satake, Masaki; Hu, Peter; Peng, Danping; Yonenaga, Dean; Tolani, Vikram


    As optical lithography continues to extend into low-k1 regime, resolution of mask patterns continues to diminish. The limitation of 1.35 NA posed by water-based lithography has led to the application of various resolution enhancement techniques (RET), for example, use of strong phase-shifting masks, aggressive OPC and sub-resolution assist features, customized illuminators, etc. The adoption of these RET techniques combined with the requirements to detect even smaller defects on masks due to increasing MEEF, poses considerable challenges for a mask inspection engineer. Inspecting masks under their actinic-aerial image conditions would detect defects that are more likely to print under those exposure conditions. However, this also makes reviewing such defects in their low-contrast aerial images very challenging. On the other hand, inspecting masks under higher resolution inspection optics would allow for better viewing of defects post-inspection. However, such inspections generally would also detect many more defects, including printable and nuisance, thereby making it difficult to judge which are of real concern for printability on wafer. Often, an inspection engineer may choose to use Aerial and/or high resolution inspection modes depending on where in the process flow the mask is and the specific device-layer characteristics of the mask. Hence, a comprehensive approach is needed in handling defects both post-aerial and post-high resolution inspections. This analysis system is designed for the Applied Materials Aera™ mask inspection platform, all data reported was collected using the Aera.

  14. Feasibility of Using Synthetic Aperture Radar to Aid UAV Navigation

    Directory of Open Access Journals (Sweden)

    Davide O. Nitti


    Full Text Available This study explores the potential of Synthetic Aperture Radar (SAR to aid Unmanned Aerial Vehicle (UAV navigation when Inertial Navigation System (INS measurements are not accurate enough to eliminate drifts from a planned trajectory. This problem can affect medium-altitude long-endurance (MALE UAV class, which permits heavy and wide payloads (as required by SAR and flights for thousands of kilometres accumulating large drifts. The basic idea is to infer position and attitude of an aerial platform by inspecting both amplitude and phase of SAR images acquired onboard. For the amplitude-based approach, the system navigation corrections are obtained by matching the actual coordinates of ground landmarks with those automatically extracted from the SAR image. When the use of SAR amplitude is unfeasible, the phase content can be exploited through SAR interferometry by using a reference Digital Terrain Model (DTM. A feasibility analysis was carried out to derive system requirements by exploring both radiometric and geometric parameters of the acquisition setting. We showed that MALE UAV, specific commercial navigation sensors and SAR systems, typical landmark position accuracy and classes, and available DTMs lead to estimated UAV coordinates with errors bounded within ±12 m, thus making feasible the proposed SAR-based backup system.

  15. Feasibility of Using Synthetic Aperture Radar to Aid UAV Navigation. (United States)

    Nitti, Davide O; Bovenga, Fabio; Chiaradia, Maria T; Greco, Mario; Pinelli, Gianpaolo


    This study explores the potential of Synthetic Aperture Radar (SAR) to aid Unmanned Aerial Vehicle (UAV) navigation when Inertial Navigation System (INS) measurements are not accurate enough to eliminate drifts from a planned trajectory. This problem can affect medium-altitude long-endurance (MALE) UAV class, which permits heavy and wide payloads (as required by SAR) and flights for thousands of kilometres accumulating large drifts. The basic idea is to infer position and attitude of an aerial platform by inspecting both amplitude and phase of SAR images acquired onboard. For the amplitude-based approach, the system navigation corrections are obtained by matching the actual coordinates of ground landmarks with those automatically extracted from the SAR image. When the use of SAR amplitude is unfeasible, the phase content can be exploited through SAR interferometry by using a reference Digital Terrain Model (DTM). A feasibility analysis was carried out to derive system requirements by exploring both radiometric and geometric parameters of the acquisition setting. We showed that MALE UAV, specific commercial navigation sensors and SAR systems, typical landmark position accuracy and classes, and available DTMs lead to estimated UAV coordinates with errors bounded within ±12 m, thus making feasible the proposed SAR-based backup system.

  16. Optical Intensity Interferometry through Atmospheric Turbulence

    CERN Document Server

    Tan, Peng Kian; Kurtsiefer, Christian


    Conventional ground-based astronomical observations suffer from image distortion due to atmospheric turbulence. This can be minimized by choosing suitable geographic locations or adaptive optical techniques, and avoided altogether by using orbital platforms outside the atmosphere. One of the promises of optical intensity interferometry is its independence from atmospherically induced phase fluctuations. By performing narrowband spectral filtering on sunlight and conducting temporal intensity interferometry using actively quenched avalanche photon detectors (APDs), the Solar $g^{(2)}(\\tau)$ signature was directly measured. We observe an averaged photon bunching signal of $g^{(2)}(\\tau) = 1.693 \\pm 0.003$ from the Sun, consistently throughout the day despite fluctuating weather conditions, cloud cover and elevation angle. This demonstrates the robustness of the intensity interferometry technique against atmospheric turbulence and opto-mechanical instabilities, and the feasibility to implement measurement scheme...

  17. Optical intensity interferometry through atmospheric turbulence (United States)

    Tan, P. K.; Chan, A. H.; Kurtsiefer, C.


    Conventional ground-based astronomical observations suffer from image distortion due to atmospheric turbulence. This can be minimized by choosing suitable geographic locations or adaptive optical techniques, and avoided altogether by using orbital platforms outside the atmosphere. One of the promises of optical intensity interferometry is its independence from atmospherically induced phase fluctuations. By performing narrow-band spectral filtering on sunlight and conducting temporal intensity interferometry using actively quenched avalanche photodiodes, the Solar g(2)(τ) signature was directly measured. We observe an averaged photon bunching signal of g(2)(τ) = 1.693 ± 0.003 from the Sun, consistently throughout the day despite fluctuating weather conditions, cloud cover and elevation angle. This demonstrates the robustness of the intensity interferometry technique against atmospheric turbulence and opto-mechanical instabilities, and the feasibility to implement measurement schemes with both large baselines and long integration times.

  18. An Adaptive Iterated Nonlocal Interferometry Filtering Method

    Directory of Open Access Journals (Sweden)

    Lin Xue


    Full Text Available Interferometry filtering is one of the key steps in obtain high-precision Digital Elevation Model (DEM and Digital Orthophoto Map (DOM. In the case of low-correlation or complicated topography, traditional phase filtering methods fail in balancing noise elimination and phase preservation, which leads to inaccurate interferometric phase. This paper proposed an adaptive iterated nonlocal interferometry filtering method to deal with the problem. Based on the thought of nonlocal filtering, the proposed method filters the image with utilization of the image redundancy information. The smoothing parameter of the method is adaptive to the interferometry, and automatic iteration, in which the window size is adjusted, is applied to improve the filtering precision. Validity of the proposed method is verified by simulated and real data. Comparison with existed methods is given at the same time.

  19. Demonstration of X-ray talbot interferometry

    CERN Document Server

    Momose, A; Kawamoto, S; Hamaishi, Y; Takai, K; Suzuki, Y


    First Talbot interferometry in the hard X-ray region was demonstrated using a pair of transmission gratings made by forming gold stripes on glass plates. By aligning the gratings on the optical axis of X-rays with a separation that caused the Talbot effect by the first grating, moire fringes were produced inclining one grating slightly against the other around the optical axis. A phase object placed in front of the first grating was detected by moire-fringe bending. Using the technique of phase-shifting interferometry, the differential phase corresponding to the phase object could also be measured. This result suggests that X-ray Talbot interferometry is a novel and simple method for phase-sensitive X-ray radiography. (author)

  20. The Wide Field Imaging Interferometry Testbed

    CERN Document Server

    Zhang, X; Leisawitz, D T; Leviton, D B; Martino, A J; Mather, J C; Zhang, Xiaolei; Feinberg, Lee; Leisawitz, Dave; Leviton, Douglas B.; Martino, Anthony J.; Mather, John C.


    We are developing a Wide-Field Imaging Interferometry Testbed (WIIT) in support of design studies for NASA's future space interferometry missions, in particular the SPIRIT and SPECS far-infrared/submillimeter interferometers. WIIT operates at optical wavelengths and uses Michelson beam combination to achieve both wide-field imaging and high-resolution spectroscopy. It will be used chiefly to test the feasibility of using a large-format detector array at the image plane of the sky to obtain wide-field interferometry images through mosaicing techniques. In this setup each detector pixel records interferograms corresponding to averaging a particular pointing range on the sky as the optical path length is scanned and as the baseline separation and orientation is varied. The final image is constructed through spatial and spectral Fourier transforms of the recorded interferograms for each pixel, followed by a mosaic/joint-deconvolution procedure of all the pixels. In this manner the image within the pointing range ...

  1. Model-based mask verification on critical 45nm logic masks (United States)

    Sundermann, F.; Foussadier, F.; Takigawa, T.; Wiley, J.; Vacca, A.; Depre, L.; Chen, G.; Bai, S.; Wang, J.-S.; Howell, R.; Arnoux, V.; Hayano, K.; Narukawa, S.; Kawashima, S.; Mohri, H.; Hayashi, N.; Miyashita, H.; Trouiller, Y.; Robert, F.; Vautrin, F.; Kerrien, G.; Planchot, J.; Martinelli, C.; Di-Maria, J. L.; Farys, V.; Vandewalle, B.; Perraud, L.; Le Denmat, J. C.; Villaret, A.; Gardin, C.; Yesilada, E.; Saied, M.


    In the continuous battle to improve critical dimension (CD) uniformity, especially for 45-nanometer (nm) logic advanced products, one important recent advance is the ability to accurately predict the mask CD uniformity contribution to the overall global wafer CD error budget. In most wafer process simulation models, mask error contribution is embedded in the optical and/or resist models. We have separated the mask effects, however, by creating a short-range mask process model (MPM) for each unique mask process and a long-range CD uniformity mask bias map (MBM) for each individual mask. By establishing a mask bias map, we are able to incorporate the mask CD uniformity signature into our modelling simulations and measure the effects on global wafer CD uniformity and hotspots. We also have examined several ways of proving the efficiency of this approach, including the analysis of OPC hot spot signatures with and without the mask bias map (see Figure 1) and by comparing the precision of the model contour prediction to wafer SEM images. In this paper we will show the different steps of mask bias map generation and use for advanced 45nm logic node layers, along with the current results of this new dynamic application to improve hot spot verification through Brion Technologies' model-based mask verification loop.

  2. Synthetic Aperture Vector Flow Imaging

    DEFF Research Database (Denmark)

    Villagómez Hoyos, Carlos Armando

    The main objective of this project was to continue the development of a synthetic aperture vector flow estimator. This type of estimator is capable of overcoming two of the major limitations in conventional ultrasound systems: 1) the inability to scan large region of interest with high temporal...... resolutions; 2) the lack of capability in detecting flow other than the one along the direction of the beam. Addressing these technical limitations would translate in the clinic as a gain in valuable clinical information and a removal of operator-dependant sources of error, which would improve the diagnosis....... The main contribution of this work was the development of an angle estimator which features high accuracy and low standard deviation over the full 360◦ range. The estimator demonstrated its capability of operating at high frame rates (> 1000 Hz), and simultaneously detecting a large range of flow...

  3. Mask process correction (MPC) modeling and its application to EUV mask for electron beam mask writer EBM-7000 (United States)

    Kamikubo, Takashi; Ohnishi, Takayuki; Hara, Shigehiro; Anze, Hirohito; Hattori, Yoshiaki; Tamamushi, Shuichi; Bai, Shufeng; Wang, Jen-Shiang; Howell, Rafael; Chen, George; Li, Jiangwei; Tao, Jun; Wiley, Jim; Kurosawa, Terunobu; Saito, Yasuko; Takigawa, Tadahiro


    In electron beam writing on EUV mask, it has been reported that CD linearity does not show simple signatures as observed with conventional COG (Cr on Glass) masks because they are caused by scattered electrons form EUV mask itself which comprises stacked heavy metals and thick multi-layers. To resolve this issue, Mask Process Correction (MPC) will be ideally applicable. Every pattern is reshaped in MPC. Therefore, the number of shots would not increase and writing time will be kept within reasonable range. In this paper, MPC is extended to modeling for correction of CD linearity errors on EUV mask. And its effectiveness is verified with simulations and experiments through actual writing test.

  4. Deflection unit for multi-beam mask making (United States)

    Letzkus, Florian; Butschke, Joerg; Irmscher, Mathias; Jurisch, Michael; Klingler, Wolfram; Platzgummer, Elmar; Klein, Christof; Loeschner, Hans; Springer, Reinhard


    Two main challenges of future mask making are the decreasing throughput of the pattern generators and the insufficient line edge roughness of the resist structures. The increasing design complexity with smaller feature sizes combined with additional pattern elements of the Optical Proximity Correction generates huge data volumes which reduce correspondingly the throughput of conventional single e-beam pattern generators. On the other hand the achievable line edge roughness when using sensitive chemically amplified resists does not fulfill the future requirements. The application of less sensitive resists may provide an improved roughness, however on account of throughput, as well. To overcome this challenge a proton multi-beam pattern generator is developed [1]. Starting with a highly parallel broad beam, an aperture-plate is used to generate thousands of separate spot beams. These beams pass through a blanking-plate unit, based on a CMOS device for de-multiplexing the writing data and equipped with electrodes placed around the apertures switching the beams "on" or "off", dependent on the desired pattern. The beam array is demagnified by a 200x reduction optics and the exposure of the entire substrate is done by a continuous moving stage. One major challenge is the fabrication of the required high aspect deflection electrodes and their connection to the CMOS device. One approach is to combine a post-processed CMOS chip with a MEMS component containing the deflection electrodes and to realize the electrical connection of both by vertical integration techniques. For the evaluation and assessment of this considered scheme and fabrication technique, a proof-of-concept deflection unit has been realized and tested. Our design is based on the generation of the deflection electrodes in a silicon membrane by etching trenches and oxide filling afterwards. In a 5mm x 5mm area 43,000 apertures with the corresponding electrodes have been structured and wired individually or in

  5. Towards Very Large Aperture Massive MIMO

    DEFF Research Database (Denmark)

    Oliveras Martínez, Àlex; De Carvalho, Elisabeth; Nielsen, Jesper Ødum


    on the impact of the array aperture which is the main limiting factor in the degrees of freedom available in the multiple antenna channel. We find that performance is improved as the aperture increases, with an impact mostly visible in crowded scenarios where the users are closely spaced. We also test MIMO...

  6. High frame rate synthetic aperture duplex imaging

    DEFF Research Database (Denmark)

    Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Pihl, Michael Johannes


    aperture flow imaging as demonstrated in this paper. Synthetic aperture, directional beamforming, and cross-correlation are used to produce B-mode and vector velocity images at high frame rates. The frame rate equals the effective pulse repetition frequency of each imaging mode. Emissions for making the B...

  7. Fast Parametric Beamformer for Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt; Tomov, Borislav Gueorguiev


    . The implementation of the beamformer is optimized with respect to the architecture of a novel synthetic aperture real-time ultrasound scanner (SARUS), in which 4 channels are processed by the same set of field-programmable gate arrays (FPGA). In synthetic transmit aperture imaging, low-resolution images are formed...

  8. Masked hypertension, a review of the literature.

    NARCIS (Netherlands)

    Verberk, W.J.; Thien, Th.; Leeuw, P.W. de


    Masked hypertension (blood pressure that is normal in the physicians' office but elevated elsewhere) is a common phenomenon as prevalence among studies varies from 8 to 45% and is seen at all ages. large discrepancies, however, exist between studies that have dealt with masked hypertension. It is of

  9. Masking the Feeling of Being Stupid. (United States)

    Smith, Sally L.


    Teaching experience at The Lab School of Washington has shown that learning-disabled children and adults cope with their lack of self-esteem and feelings of stupidity by developing masks to hide their hurt. These include masks of super-competence, helplessness, invisibility, clowning, injustice collecting, indifference, boredom, outrageousness,…

  10. Computing Challenges in Coded Mask Imaging (United States)

    Skinner, Gerald


    This slide presaentation reviews the complications and challenges in developing computer systems for Coded Mask Imaging telescopes. The coded mask technique is used when there is no other way to create the telescope, (i.e., when there are wide fields of view, high energies for focusing or low energies for the Compton/Tracker Techniques and very good angular resolution.) The coded mask telescope is described, and the mask is reviewed. The coded Masks for the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) instruments are shown, and a chart showing the types of position sensitive detectors used for the coded mask telescopes is also reviewed. Slides describe the mechanism of recovering an image from the masked pattern. The correlation with the mask pattern is described. The Matrix approach is reviewed, and other approaches to image reconstruction are described. Included in the presentation is a review of the Energetic X-ray Imaging Survey Telescope (EXIST) / High Energy Telescope (HET), with information about the mission, the operation of the telescope, comparison of the EXIST/HET with the SWIFT/BAT and details of the design of the EXIST/HET.

  11. A facial mask comprising Dead Sea mud. (United States)

    Abu-Jdayil, Basim; Mohameed, Hazim A


    Many investigators have proved that Dead Sea salt and mud are useful in treating skin disorders and skin diseases. Therefore, the black mud has been extensively used as a base for the preparation of soaps, creams, and unguents for skin care. This study concerns a facial mask made mainly of Dead Sea mud. The effects of temperature and shearing conditions on the rheological behavior of the facial mask were investigated. The mud facial mask exhibited a shear thinning behavior with a yield stress. It was found that the apparent viscosity of the mask has a strong dependence on the shear rate as well as on the temperature. The facial mask exhibited a maximum yield stress and very shear thinning behavior at 40 degrees C, which is attributed to the gelatinization of the polysaccharide used to stabilize the mud particles. On the other hand, the mud mask exhibited a time-independent behavior at low temperatures and shear rates and changed to a thixotropic behavior upon increasing both the temperature and the shear rate. The shear thinning and thixotropic behaviors have a significant importance in the ability of the facial mask to spread on the skin: the Dead Sea mud mask can break down for easy spreading, and the applied film can gain viscosity instantaneously to resist running. Moreover, particle sedimentation, which in this case would negatively affect consumer acceptance of the product, occurs slowly due to high viscosity at rest conditions.

  12. Interferometry to Image Surface Spots (United States)

    Perrin, Guy


    I present in this lecture the technique of interferometric imaging at optical/infrared wavelengths. The technique has matured since the pioneering work of Michelson at the end of the XIXth—beginning of the XXth when he first resolved the surface of a star, Betelgeuse, with his colleague Pease. Images were obtained for the first time 20 years ago with the COAST instrument and interferometers have made constant progress to reach the minimum level where blind image reconstruction can be achieved. I briefly introduce the topic to recall why studying the surface and close environment of stars is important in some fields of stellar physics. I introduce the theory of imaging with telescopes and interferometers. I discuss the nature of interferometric data in this wavelength domain and give a few insights on the importance of getting access to visibility phases to obtain information on asymmetries of stellar surfaces. I then present the issue of aperture synthesis with a small number of telescopes, a signature of optical/infrared interferometers compared to the radio domain. Despite the impossibility to measure the phase of visibilities because of turbulence I show that useful information can be recovered from the closure phase. I eventually introduce the principles of image reconstruction and I discuss some recent results on several types of stars.

  13. Scanning coherent diffractive imaging methods for actinic extreme ultraviolet mask metrology (United States)

    Helfenstein, Patrick; Mohacsi, Istvan; Rajeev, Rajendran; Ekinci, Yasin


    For the successful implementation of extreme ultraviolet (EUV) lithography in the upcoming technology nodes, a major challenge to overcome is the stable and reliable detection and characterization of mask defects. We have recently presented a reflective mode EUV mask scanning lensless imaging tool (RESCAN) which was installed at the XIL-II beamline of the swiss light source and showed reconstructed aerial images of test patterns on EUV masks. RESCAN uses scanning coherent diffractive imaging (SCDI) methods to obtain actinic aerial images of EUV photomasks and was designed for 80 nm onmask resolution. Our SCDI algorithm reconstructs the measured sample by iteratively solving the phase problem using overdetermined diffraction data gathered by scanning across the specimen with a finite illumination. It provides the phase and amplitude aerial images of EUV photomasks with high resolution without the need to use high numerical aperture (NA) lenses. Contrary to scanning microscopy and full-field microscopy, where the resolution is limited by the spot size or NA of the lens, the achievable resolution with our method depends on the detector noise and NA of the detector. To increase the resolution of our tool, we upgraded RESCAN with a detector and algorithms. Here, we present the results obtained with the tool that is capable of up to 40-nm onmask resolution. We believe that the realization of our prototype marks a significant step toward overcoming the limitations imposed by methods relying on imaging optics and shows a viable solution for actinic mask metrology.

  14. Laser Micromachining and Information Discovery Using a Dual Beam Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Senthil P. Theppakuttaikomaraswamy


    Lasers have proven to be among the most promising tools for micromachining because they can process features down to the size of the laser wavelength (smaller than 1 micrometer) and they provide a non-contact technology for machining. The demand for incorporating in-situ diagnostics technology into the micromachining environment is driven by the increasing need for producing micro-parts of high quality and accuracy. Laser interferometry can be used as an on-line monitoring tool and it is the aim of this work to enhance the understanding and application of Michelson interferometry principle for the in-situ diagnostics of the machining depth on the sub-micron and micron scales. micromachining is done on two different materials and a comprehensive investigation is done to control the width and depth of the machined feature. To control the width of the feature, laser micromachining is done on copper and a detailed analysis is performed. The objective of this experiment is to make a precision mask for sputtering with an array of holes on it using an Nd:YAG laser of 532 nm wavelength. The diameter of the hole is 50 {micro}m and the spacing between holes (the distance between the centers) is 100 {micro}m. Michelson interferometer is integrated with a laser machining system to control the depth of machining. An excimer laser of 308 nm wavelength is used for micromachining. A He-Ne laser of 632.8 nm wavelength is used as the light source for the interferometer. Interference patterns are created due to the change in the path length between the two interferometer arms. The machined depth information is obtained from the interference patterns on an oscilloscope detected by a photodiode. To compare the predicted depth by the interferometer with the true machining depth, a surface profilometer is used to measure the actual machining depth on the silicon. It is observed that the depths of machining obtained by the surface profile measurement are in accordance with the

  15. Laser Micromachining and Information Discovery Using a Dual Beam Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Theppakuttaikomaraswamy, Senthil P. [Iowa State Univ., Ames, IA (United States)


    Lasers have proven to be among the most promising tools for micromachining because they can process features down to the size of the laser wavelength (smaller than 1 micrometer) and they provide a non-contact technology for machining. The demand for incorporating in-situ diagnostics technology into the micromachining environment is driven by the increasing need for producing micro-parts of high quality and accuracy. Laser interferometry can be used as an on-line monitoring tool and it is the aim of this work to enhance the understanding and application of Michelson interferometry principle for the in-situ diagnostics of the machining depth on the sub-micron and micron scales. micromachining is done on two different materials and a comprehensive investigation is done to control the width and depth of the machined feature. To control the width of the feature, laser micromachining is done on copper and a detailed analysis is performed. The objective of this experiment is to make a precision mask for sputtering with an array of holes on it using an Nd:YAG laser of 532 nm wavelength. The diameter of the hole is 50 μm and the spacing between holes (the distance between the centers) is 100 μm. Michelson interferometer is integrated with a laser machining system to control the depth of machining. An excimer laser of 308 nm wavelength is used for micromachining. A He-Ne laser of 632.8 nm wavelength is used as the light source for the interferometer. Interference patterns are created due to the change in the path length between the two interferometer arms. The machined depth information is obtained from the interference patterns on an oscilloscope detected by a photodiode. To compare the predicted depth by the interferometer with the true machining depth, a surface profilometer is used to measure the actual machining depth on the silicon. It is observed that the depths of machining obtained by the surface profile measurement are in accordance with the interferometer

  16. Monitoring civil infrastructure using satellite radar interferometry

    NARCIS (Netherlands)

    Chang, L.


    Satellite radar interferometry (InSAR) is a precise and efficient technique to monitor deformation on Earth with millimeter precision. Most InSAR applications focus on geophysical phenomena, such as earthquakes, volcanoes, or subsidence. Monitoring civil infrastructure with InSAR is relatively new,

  17. Airborne Repeat Pass Interferometry for Deformation Measurements

    NARCIS (Netherlands)

    Groot, J.; Otten, M.; Halsema, E. van


    In ground engineering the need for deformation measurements is urgent. SAR interferometry can be used to measure small (sub-wavelength) deformations. An experiment to investigate this for dike deformations was set up, using the C-band SAR system PHARUS (PHased ARray Universal SAR). This paper descri

  18. Basic radio interferometry for future lunar missions

    NARCIS (Netherlands)

    Aminaei, Amin; Klein Wolt, Marc; Chen, Linjie; Bronzwaer, Thomas; Pourshaghaghi, Hamid Reza; Bentum, Mark J.; Falcke, Heino


    In light of presently considered lunar missions, we investigate the feasibility of the basic radio interferometry (RIF) for lunar missions. We discuss the deployment of two-element radio interferometer on the Moon surface. With the first antenna element is envisaged to be placed on the lunar lander,

  19. Constraining symmetron fields with atom interferometry

    CERN Document Server

    Burrage, Clare; Stevenson, James; Thrussell, Ben


    We apply the new constraints from atom-interferometry searches for screening mechanisms to the symmetron model, finding that these experiments exclude a previously unexplored region of parameter space. We discuss the possibility of networks of domain walls forming in the vacuum chamber, and how this could be used to discriminate between models of screening.

  20. Results from a multi aperture Fizeau interferometer ground testbed: demonstrator for a future space-based interferometer (United States)

    Baccichet, Nicola; Caillat, Amandine; Rakotonimbahy, Eddy; Dohlen, Kjetil; Savini, Giorgio; Marcos, Michel


    In the framework of the European FP7-FISICA (Far Infrared Space Interferometer Critical Assessment) program, we developed a miniaturized version of the hyper-telescope to demonstrate multi-aperture interferometry on ground. This setup would be ultimately integrated into a CubeSat platform, therefore providing the first real demonstrator of a multi aperture Fizeau interferometer in space. In this paper, we describe the optical design of the ground testbed and the data processing pipeline implemented to reconstruct the object image from interferometric data. As a scientific application, we measured the Sun diameter by fitting a limb-darkening model to our data. Finally, we present the design of a CubeSat platform carrying this miniature Fizeau interferometer, which could be used to monitor the Sun diameter over a long in-orbit period.

  1. Evaluation Of Digital Unsharp-Mask Filtering For The Detection Of Subtle Mammographic Microcalcifications (United States)

    Chan, Heang-Ping; Vyborny, Carl J.; MacMahon, Heber; Metz, Charles E.; Doi, Kunio; Sickles, Edward A.


    We have conducted a study to assess the effects of digitization and unsharp-mask filtering on the ability of observers to detect subtle microcalcifications in mammograms. Thirty-two conventional screen-film mammograms were selected from patient files by two experienced mammographers. Twelve of the mammograms contained a suspicious cluster of microcalcifications in patients who subsequently underwent biopsy. Twenty of the mammograms were normal cases which were initially interpreted as being free of clustered microcalcifications and did not demonstrate such on careful review. The mammograms were digitized with a high-quality Fuji image processing/simulation system. The system consists of two drum scanners with which an original radiograph can be digitized, processed by a minicomputer, and reconstituted on film. In this study, we employed a sampling aperture of 0.1 mm X 0.1 mm and a sampling distance of 0.1 mm. The density range from 0.2 to 2.75 was digitized to 1024 grey levels per pixel. The digitized images were printed on a single emulsion film with a display aperture having the same size as the sampling aperture. The system was carefully calibrated so that the density and contrast of a digitized image were closely matched to those of the original radiograph. Initially, we evaluated the effects of the weighting factor and the mask size of a unsharp-mask filter on the appearance of mammograms for various types of breasts. Subjective visual comparisons suggested that a mask size of 91 X 91 pixels (9.1 mm X 9.1 mm) enhances the visibility of microcalcifications without excessively increasing the high-frequency noise. Further, a density-dependent weighting factor that increases linearly from 1.5 to 3.0 in the density range of 0.2 to 2.5 enhances the contrast of microcalcifications without introducing many potentially confusing artifacts in the low-density areas. An unsharp-mask filter with these parameters was used to process the digitized mammograms. We conducted

  2. Nonpolar III-nitride vertical-cavity surface-emitting laser with a photoelectrochemically etched air-gap aperture

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, J. T., E-mail:; Yonkee, B. P.; Cohen, D. A.; Megalini, L.; Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Lee, S. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); DenBaars, S. P.; Nakamura, S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)


    We demonstrate a III-nitride nonpolar vertical-cavity surface-emitting laser (VCSEL) with a photoelectrochemically (PEC) etched aperture. The PEC lateral undercut etch is used to selectively remove the multi-quantum well (MQW) region outside the aperture area, defined by an opaque metal mask. This PEC aperture (PECA) creates an air-gap in the passive area of the device, allowing one to achieve efficient electrical confinement within the aperture, while simultaneously achieving a large index contrast between core of the device (the MQW within the aperture) and the lateral cladding of the device (the air-gap formed by the PEC etch), leading to strong lateral confinement. Scanning electron microscopy and focused ion-beam analysis is used to investigate the precision of the PEC etch technique in defining the aperture. The fabricated single mode PECA VCSEL shows a threshold current density of ∼22 kA/cm{sup 2} (25 mA), with a peak output power of ∼180 μW, at an emission wavelength of 417 nm. The near-field emission profile shows a clearly defined single linearly polarized (LP) mode profile (LP{sub 12,1}), which is in contrast to the filamentary lasing that is often observed in III-nitride VCSELs. 2D mode profile simulations, carried out using COMSOL, give insight into the different mode profiles that one would expect to be displayed in such a device. The experimentally observed single mode operation is proposed to be predominantly a result of poor current spreading in the device. This non-uniform current spreading results in a higher injected current at the periphery of the aperture, which favors LP modes with high intensities near the edge of the aperture.

  3. Masking property of quantum random cipher with phase mask encryption (United States)

    Sohma, Masaki; Hirota, Osamu


    The security analysis of physical encryption protocol based on coherent pulse position modulation (CPPM) originated by Yuen is one of the most interesting topics in the study of cryptosystem with a security level beyond the Shannon limit. Although the implementation of CPPM scheme has certain difficulty, several methods have been proposed recently. This paper deals with the CPPM encryption in terms of symplectic transformation, which includes a phase mask encryption as a special example, and formulates a unified security analysis for such encryption schemes. Specifically, we give a lower bound of Eve's symbol error probability using reliability function theory to ensure that our proposed system exceeds the Shannon limit. Then we assume the secret key is given to Eve after her heterodyne measurement. Since this assumption means that Eve has a great advantage in the sense of the conventional cryptography, the lower bound of her error indeed ensures the security level beyond the Shannon limit. In addition, we show some numerical examples of the security performance.

  4. Walking through Apertures in Individuals with Stroke (United States)

    Higuchi, Takahiro


    Objective Walking through a narrow aperture requires unique postural configurations, i.e., body rotation in the yaw dimension. Stroke individuals may have difficulty performing the body rotations due to motor paralysis on one side of their body. The present study was therefore designed to investigate how successfully such individuals walk through apertures and how they perform body rotation behavior. Method Stroke fallers (n = 10), stroke non-fallers (n = 13), and healthy controls (n = 23) participated. In the main task, participants walked for 4 m and passed through apertures of various widths (0.9–1.3 times the participant’s shoulder width). Accidental contact with the frame of an aperture and kinematic characteristics at the moment of aperture crossing were measured. Participants also performed a perceptual judgment task to measure the accuracy of their perceived aperture passability. Results and Discussion Stroke fallers made frequent contacts on their paretic side; however, the contacts were not frequent when they penetrated apertures from their paretic side. Stroke fallers and non-fallers rotated their body with multiple steps, rather than a single step, to deal with their motor paralysis. Although the minimum passable width was greater for stroke fallers, the body rotation angle was comparable among groups. This suggests that frequent contact in stroke fallers was due to insufficient body rotation. The fact that there was no significant group difference in the perceived aperture passability suggested that contact occurred mainly due to locomotor factors rather than perceptual factors. Two possible explanations (availability of vision and/or attention) were provided as to why accidental contact on the paretic side did not occur frequently when stroke fallers penetrated the apertures from their paretic side. PMID:28103299

  5. Direct unwrapped phase estimation in phase shifting interferometry using Levenberg–Marquardt algorithm (United States)

    Kulkarni, Rishikesh; Rastogi, Pramod


    An algorithm for the direct unwrapped phase estimation from the linearly phase shifted interferograms is presented. The temporal fringe intensity along each pixel is represented as a function of fringe amplitude, phase step and the searched phase. These parameters are estimated in the nonlinear least squares sense using the Levenberg–Marquardt algorithm. The proposed method allows the masked interferograms to be handled using a pixel selection approach to provide the appropriate initial conditions at a given pixel utilizing the estimated parameters at one of its neighboring pixels, which results in direct unwrapped phase estimation. Simulation results are provided to evaluate the performance of the proposed method as a function of noise power, spatially varying phase step, number of interferograms and phase step detuning error. The experimental results are also provided in the case of a holographic interferometry setup.

  6. Space and time in masking and crowding. (United States)

    Lev, Maria; Polat, Uri


    Masking and crowding are major phenomena associated with contextual modulations, but the relationship between them remains unclear. We have recently shown that crowding is apparent in the fovea when the time available for processing is limited, pointing to the strong relationship between crowding in the spatial and temporal domains. Models of crowding emphasize the size (acuity) of the target and the spacing between the target and flankers as the main determinants that predict crowding. Our model, which is based on lateral interactions, posits that masking and crowding are related in the spatial and temporal domains at the fovea and periphery and that both can be explained by the increasing size of the human perceptive field (PF) with increasing eccentricity. We explored the relations between masking and crowding using letter identification and contrast detection by correlating the crowding effect with the estimated size of the PF and with masking under different spatiotemporal conditions. We found that there is a large variability in PF size and crowding effects across observers. Nevertheless, masking and crowding were both correlated with the estimated size of the PF in the fovea and periphery under a specific range of spatiotemporal parameters. Our results suggest that under certain conditions, crowding and masking share common neural mechanisms that underlie the spatiotemporal properties of these phenomena in both the fovea and periphery. These results could explain the transfer of training gains from spatiotemporal Gabor masking to letter acuity, reading, and reduced crowding.

  7. Intact crowding and temporal masking in dyslexia. (United States)

    Doron, Adi; Manassi, Mauro; Herzog, Michael H; Ahissar, Merav


    Phonological deficits in dyslexia are well documented. However, there is an ongoing discussion about whether visual deficits limit the reading skills of people with dyslexia. Here, we investigated visual crowding and backward masking. We presented a Vernier (i.e., two vertical bars slightly offset to the left or right) and asked observers to indicate the offset direction. Vernier stimuli are visually similar to letters and are strongly affected by crowding, even in the fovea. To increase task difficulty, Verniers are often followed by a mask (i.e., backward masking). We measured Vernier offset discrimination thresholds for the basic Vernier task, under crowding, and under backward masking, in students with dyslexia (n = 19) and age and intelligence matched students (n = 27). We found no group differences in any of these conditions. Controls with fast visual processing (good backward masking performance), were faster readers. By contrast, no such correlation was found among the students with dyslexia, suggesting that backward masking does not limit their reading efficiency. These findings indicate that neither elevated crowding nor elevated backward masking pose a bottleneck to reading skills of people with dyslexia.

  8. Practical Applications of Synthetic Aperture Imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav Ivanov; Kortbek, Jacob; Jensen, Jørgen Arendt


    Synthetic aperture imaging has been a focus of research for almost 3 decades. The research carried out at the Center for Fast Ultrasound Imaging has demonstrated that synthetic aperture focusing not only can be used in-vivo, but that it also yields superior B-mode and blood flow images. In the last......, and multiple angle flash imaging are just a few of the names used to describe the commercial implementations of synthetic aperture focusing. Although they sound like different algorithms, they are the same in their core, as revealed in this paper....

  9. Passive microwave imaging by aperture synthesis technology (United States)

    Lang, Liang; Zhang, Zuyin; Guo, Wei; Gui, Liangqi


    In order to verify the theory of aperture synthesis at low expense, two-channel ka-band correlation radiometer which is basic part of synthetic aperture radiometer is designed firstly before developing the multi-channel synthetic aperture radiometer. The performance of two-channel correlation radiometer such as stability and coherence of visibility phase are tested in the digital correlation experiment. Subsequently all required baselines are acquired by moving the antenna pair sequentially, corresponding samples of the visibility function are measured and the image of noise source is constructed using an inverse Fourier transformation.

  10. Long-baseline optical intensity interferometry: Laboratory demonstration of diffraction-limited imaging

    CERN Document Server

    Dravins, Dainis; Nuñez, Paul D


    A long-held vision has been to realize diffraction-limited optical aperture synthesis over kilometer baselines. This will enable imaging of stellar surfaces and their environments, and reveal interacting gas flows in binary systems. An opportunity is now opening up with the large telescope arrays primarily erected for measuring Cherenkov light in air induced by gamma rays. With suitable software, such telescopes could be electronically connected and also used for intensity interferometry. Second-order spatial coherence of light is obtained by cross correlating intensity fluctuations measured in different pairs of telescopes. With no optical links between them, the error budget is set by the electronic time resolution of a few nanoseconds. Corresponding light-travel distances are approximately one meter, making the method practically immune to atmospheric turbulence or optical imperfections, permitting both very long baselines and observing at short optical wavelengths. Previous theoretical modeling has shown ...

  11. On the application of SAR interferometry to geomorphological studies: estimation of landform attributes and mass movements (United States)

    Catani, Filippo; Farina, Paolo; Moretti, Sandro; Nico, Giovanni; Strozzi, Tazio


    This paper presents two examples of application of Synthetic Aperture Radar (SAR) interferometry (InSAR) to typical geomorphological problems. The principles of InSAR are introduced, taking care to clarify the limits and the potential of this technique for geomorphological studies. The application of InSAR to the quantification of landform attributes such as the slope and to the estimation of landform variations is investigated. Two case studies are presented. A first case study focuses on the problem of measuring landform attributes by interferometric SAR data. The interferometric result is compared with the corresponding one obtained by a Digital Elevation Model (DEM). In the second case study, the use of InSAR for the estimation of landform variations caused by a landslide is detailed.

  12. The coseismic displacement field of the Zhangbei-Shangyi earthquake mapped by differential radar interferometry

    Institute of Scientific and Technical Information of China (English)


    The coseismic deformation produced by 1998 earthquake (Ms = 6.2) in Zhangbei-Shangyi of northern China is measured by the differential synthetic aperture radar interferometry (D-InSAR) technique using the European Remote Sensing satellite (ERS) SAR data. Interferograms are constructed from the ERS-1/2 SAR data by the three-pass method. The line-of-sight displacement map indicates that the deformation center of the earthquake is located at E114°20′,N40°57′,with the maximum uplift of 25 cm. The extent of the displacement is around 300 km2. The focal mechanism and earthquake-induced structures are analyzed based on the spatial distribution of the deformation. The results give new insights into the seismic mechanism study.

  13. Interseismic deformation of the Shahroud fault system (NE Iran) from space-borne radar interferometry measurements (United States)

    Mousavi, Z.; Pathier, E.; Walker, R. T.; Walpersdorf, A.; Tavakoli, F.; Nankali, H.; Sedighi, M.; Doin, M.-P.


    The Shahroud fault system is a major active structure in the Alborz range of NE Iran whose slip rate is not well constrained despite its potential high seismic hazard. In order to constrain the slip rate of the eastern Shahroud fault zone, we use space-borne synthetic aperture radar interferometry with both ascending and descending Envisat data to determine the rate of interseismic strain accumulation across the system. We invert the slip rate from surface velocity measurements using a half-space elastic dislocation model. The modeling results are consistent with a left-lateral slip rate of 4.75 ± 0.8 mm/yr on the Abr and Jajarm, strands of the Shahroud fault, with a 10 ± 4 km locking depth. This is in good agreement with the 4-6 mm/yr of left-lateral displacement rate accumulated across the total Shahroud fault system obtained from GPS measurements.

  14. Stellar intensity interferometry over kilometer baselines: Laboratory simulation of observations with the Cherenkov Telescope Array

    CERN Document Server

    Dravins, Dainis


    A long-held astronomical vision is to realize diffraction-limited optical aperture synthesis over kilometer baselines. This will enable imaging of stellar surfaces and their environments, show their evolution over time, and reveal interactions of stellar winds and gas flows in binary star systems. An opportunity is now opening up with the large telescope arrays primarily erected for measuring Cherenkov light in air induced by gamma rays. With suitable software, such telescopes could be electronically connected and used also for intensity interferometry. With no optical connection between the telescopes, the error budget is set by the electronic time resolution of a few nanoseconds. Corresponding light-travel distances are on the order of one meter, making the method practically insensitive to atmospheric turbulence or optical imperfections, permitting both very long baselines and observing at short optical wavelengths. Theoretical modeling has shown how stellar surface images can be retrieved from such observ...

  15. Printed shadow masks for organic transistors (United States)

    Noguchi, Yoshiaki; Sekitani, Tsuyoshi; Someya, Takao


    We have manufactured organic field-effect transistors by using shadow masks that are patterned by a screen printing system. The 50-nm-thick pentacene layer is sublimed as a channel in the vacuum system through the shadow mask on the base film with a multilayer patterned by ink-jet. After the deposition of the pentacene layer, the shadow mask is peeled off from the base film without any mechanical damages to the lower structures. The mobility in the saturation regime is 0.4cm2/Vs and the on-off ratio exceeds 105.

  16. Periodic wrappings in coded aperture imaging (United States)

    Shutler, Paul M. E.; Springham, Stuart V.; Talebitaher, Alireza


    We classify all coded masks onto which cyclic difference sets can be wrapped periodically using a generalization of the Finger and Prince construction. In particular, we establish simple numerical criteria which determine whether any given mask can be wrapped periodically in this way and, for each mask which can, we provide explicit constructions which will produce at least one such wrapping. We show that all periodic wrappings currently reported in the literature are special cases of our explicit constructions, and we often provide simpler alternatives. Using these constructions we show that all Singer cyclic difference sets of practical size and open fraction can be wrapped exactly onto masks which are very nearly as compact and symmetrical as hexagons, without the need for pixel padding.

  17. Tom Pickering as a clinical scientist: masked hypertension. (United States)

    Eguchi, Kazuo


    Masked hypertension has been 'unmasked' by the use of the out-of-office measurement of blood pressure, as home BP monitoring or ambulatory blood pressure monitoring has become available. The term masked hypertension could be used more widely than the original version of masked hypertension; morning hypertension, stress-induced hypertension, and nocturnal hypertension are all classified as subtypes of masked hypertension. Masked hypertension can also be seen in patients with diabetes, that could change clinical practice in diabetes. Masked hypertension is associated with cardiovascular events, but most of the outcome studies are on antihypertensive medications. Therefore, masked hypertension includes insufficient treatment of hypertension. In Dr Pickering's latest review of masked hypertension, prehypertension or high normal blood pressure was stressed as an associating factor with masked hypertension. The biggest theme in the field of hypertension is how we can detect masked hypertension. I present two interesting cases of possible masked hypertension in this commentary.

  18. Use of Synthetic Aperture Radar in Cold Climate Flood Response (United States)

    Yarbrough, L. D.


    The purpose of this study was to investigate the usefulness of Synthetic Aperture Radar (SAR) satellite images during a cold climate disaster response event. There were 15 European Space Agency (ESA) Advanced Synthetic Aperture Radar ASAR scenes, five Japan Aerospace Exploration Agency (JAXA) Phased Array type L-band Synthetic Aperture Radar (PALSAR) scenes, one RADARSAT2 scene, and numerous optical sensor data. These data were primarily used to indentify floodwater inundation polygons and flow vectors. However, in cold climate flooding, there are complicating factors such as frazil ice, ice jams, and snow-covered, frozen flood waters that are not present during warmer flooding events. The imagery was obtained through the International Charter "Space and Major Disasters.” The Charter aims at providing a unified system of space data acquisition and delivery to those affected by natural or man-made disasters through Authorized Users. Each member agency has committed resources to support the provisions of the Charter, and thus is helping to mitigate the effects of disasters on human life and property. On 25 March 2009, the Charter was activated in response to the flooding along the Red River of the North in the states of North Dakota and Minnesota of the United States. The delivery time of a single SAR scene from a Charter participant was less than 12 hours from the time of acquisition. This expedited service allowed additional time for creating image-based derivations, field checking and delivery to a decision maker or emergency responder. SAR-derived data sets include identification of river ice and saturated ground conditions. This data could be provided to experts in river ice engineering for use in the development of plans to reduce ice jamming, its effect on water levels and additional stresses on river infrastructure. During disaster response applications, SAR data was found to very useful in indentifying open water and the front of ice jams. Using a river

  19. Synthetic Aperture Radar Missions Study Report (United States)

    Bard, S.


    This report reviews the history of the LightSAR project and summarizes actions the agency can undertake to support industry-led efforts to develop an operational synthetic aperture radar (SAR) capability in the United States.

  20. Beam Combination for Sparse Aperture Telescopes Project (United States)

    National Aeronautics and Space Administration — The Stellar Imager, an ultraviolet, sparse-aperture telescope, was one of the fifteen Vision Missions chosen for a study completed last year. Stellar Imager will...

  1. Beam Combination for Sparse Aperture Telescopes Project (United States)

    National Aeronautics and Space Administration — This proposal is for funding to continue development of an alternative beam combiner for Stellar Imager (SI), a 30-aperture, interferometric telescope chosen as one...

  2. Intensity interferometry with Aqueye+ and Iqueye in Asiago (United States)

    Zampieri, Luca; Naletto, Giampiero; Barbieri, Cesare; Barbieri, Mauro; Verroi, Enrico; Umbriaco, Gabriele; Favazza, Paolo; Lessio, Luigi; Farisato, Giancarlo


    Since a number of years our group is engaged in the design, construction and operation of instruments with very high time resolution in the optical band for applications to Quantum Astronomy and more conventional Astrophysics. Two instruments were built to perform photon counting with sub-nanosecond temporal accuracy. The first of the two, Aqueye+, is regularly mounted at the 1.8 m Copernicus telescope in Asiago, while the second one, Iqueye, was mounted at the ESO New Technology Telescope in Chile, and at the William Herschel Telescope and Telescopio Nazionale Galileo on the Roque (La Palma, Canary Islands). Both instruments deliver extraordinarily accurate results in optical pulsar timing. Recently, Iqueye was moved to Asiago to be mounted at the 1.2 m Galileo telescope to attempt, for the first time ever, experiments of optical intensity interferometry (à la Hanbury Brown and Twiss) on a baseline of a few kilometers, together with the Copernicus telescope. This application was one of the original goals for the development of our instrumentation. To carry out these measurements, we are experimenting a new way of coupling the instruments to the telescopes, by means of moderate-aperture, low-optical-attenuation multi-mode optical fibers with a double-clad design. Fibers are housed in dedicated optical interfaces attached to the focus of another instrument of the 1.8 m telescope (Aqueye+) or to the Nasmyth focus of the 1.2 m telescope (Iqueye). This soft-mount solution has the advantage to facilitate the mounting of the photon counters, to keep them under controlled temperature and humidity conditions (reducing potential systematics related to varying ambient conditions), and to mitigate scheduling requirements. Here we will describe the first successful implementation of the Asiago intensity interferometer and future plans for improving it.

  3. Calculation and Error Analysis of a Digital Elevation Model of Hofsjokull, Iceland from SAR Interferometry (United States)

    Barton, Jonathan S.; Hall, Dorothy K.; Sigurosson, Oddur; Williams, Richard S., Jr.; Smith, Laurence C.; Garvin, James B.


    Two ascending European Space Agency (ESA) Earth Resources Satellites (ERS)-1/-2 tandem-mode, synthetic aperture radar (SAR) pairs are used to calculate the surface elevation of Hofsjokull, an ice cap in central Iceland. The motion component of the interferometric phase is calculated using the 30 arc-second resolution USGS GTOPO30 global digital elevation product and one of the ERS tandem pairs. The topography is then derived by subtracting the motion component from the other tandem pair. In order to assess the accuracy of the resultant digital elevation model (DEM), a geodetic airborne laser-altimetry swath is compared with the elevations derived from the interferometry. The DEM is also compared with elevations derived from a digitized topographic map of the ice cap from the University of Iceland Science Institute. Results show that low temporal correlation is a significant problem for the application of interferometry to small, low-elevation ice caps, even over a one-day repeat interval, and especially at the higher elevations. Results also show that an uncompensated error in the phase, ramping from northwest to southeast, present after tying the DEM to ground-control points, has resulted in a systematic error across the DEM.

  4. Seismic interferometry of railroad induced ground motions: body and surface wave imaging (United States)

    Quiros, Diego A.; Brown, Larry D.; Kim, Doyeon


    Seismic interferometry applied to 120 hr of railroad traffic recorded by an array of vertical component seismographs along a railway within the Rio Grande rift has recovered surface and body waves characteristic of the geology beneath the railway. Linear and hyperbolic arrivals are retrieved that agree with surface (Rayleigh), direct and reflected P waves observed by nearby conventional seismic surveys. Train-generated Rayleigh waves span a range of frequencies significantly higher than those recovered from typical ambient noise interferometry studies. Direct P-wave arrivals have apparent velocities appropriate for the shallow geology of the survey area. Significant reflected P-wave energy is also present at relatively large offsets. A common midpoint stack produces a reflection image consistent with nearby conventional reflection data. We suggest that for sources at the free surface (e.g. trains) increasing the aperture of the array to record wide angle reflections, in addition to longer recording intervals, might allow the recovery of deeper geological structure from railroad traffic. Frequency-wavenumber analyses of these recordings indicate that the train source is symmetrical (i.e. approaching and receding) and that deeper refracted energy is present although not evident in the time-offset domain. These results confirm that train-generated vibrations represent a practical source of high-resolution subsurface information, with particular relevance to geotechnical and environmental applications.

  5. Fundamental aspects of resolution and precision in vertical scanning white-light interferometry (United States)

    Lehmann, Peter; Tereschenko, Stanislav; Xie, Weichang


    We discuss the height and lateral resolution that can be achieved in vertical scanning white-light interferometry (SWLI). With respect to interferometric height resolution, phase-shifting interferometry (PSI) is assumed to provide the highest accuracy. However, if the noise dependence of SWLI phase evaluation and PSI algorithms is considered, SWLI measurements can be shown to be more precise. With respect to lateral resolution, the determination of the coherence peak position of SWLI signals seems to lead to better results compared to phase based-interferometric measurements. This can be attributed to the well-known batwing effect. Since batwing is a nonlinear effect applying nonlinear filters, e.g. a median filter, it reduces them significantly. If filtering is applied prior to the fringe order determination and phase evaluation, the number of artefacts known as ghost steps can be eliminated without changing the modulus of the phase. Finally, we discuss the dependence of measured height values on surface slope. We show that in interference microscopy there are additional limitations which are more rigid compared to the maximum surface slope angle resulting from the numerical aperture of the objective lens. As a consequence, the measurement precision breaks down at slope changes of steeper flanks even if the modulation depth of the interference signals is still good enough for signal analysis.

  6. Micromorphology of epicuticular waxes and epistomatal chambers of pine species by electron microscopy and white light scanning interferometry. (United States)

    Kim, Ki Woo; Lee, In Jung; Kim, Chang Soo; Lee, Don Koo; Park, Eun Woo


    High-resolution imaging and quantitative surface analysis of epicuticular waxes and epistomatal chambers of pine species were performed by field emission scanning electron microscopy and white light scanning interferometry. Both juvenile and adult needles were collected from the two-year-old seedlings of Pinus rigida and Pinus densiflora and subjected to surface observations. Epicuticular wax structures developed on the cuticle layer as well as in the epistomatal chambers and appeared to occlude the cavities in the two pine species. The stomata of P. densiflora were characterized by more distinctly raised rings around openings than P. rigida. The most common epicuticular wax structures of the two pine species included tubules with terminal openings and coiled rodlets. Wax platelets were deposited on epistomatal chambers. Either rodlets or tubules seemed to be longer and thicker in P. rigida than those in P. densiflora. White light scanning interferometry revealed quantitative surface profiles, demonstrating more ridged (ca. 4 μm high) stomatal apertures and nearly twofold deeper (ca. 20 μm deep) epistomatal chambers of P. densiflora than those of P. rigida. These results suggest that white light scanning interferometry can be applied to unravel the quantitative surface features of epicuticular sculptures on plant leaves.

  7. Parametric Transverse Patterns in Broad Aperture Lasers

    DEFF Research Database (Denmark)

    Grigorieva, E.V.; Kashchenko, S.A.; Mosekilde, Erik


    Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence on the geo......Parametrically generated optical patterns are investigated for finite and large-scale transverse aperture lasers. Standing and rotating patterns as well as periodic and chaotic pattern alternations are described in the framework of the amplitude equation formalism. Sensitive dependence...

  8. Polishing Your Transparencies: Mounting, Masking, Overlays. (United States)

    Jobe, Holly; Cannon, Glenn

    This brief guide discusses the mounting of overhead transparencies on frames, the types of mounts, the proper masking for presentation, and the use of overlays. Numerous line drawings provide the reader with a helpful visual reference. (RAO)

  9. Masking of aluminum surface against anodizing (United States)

    Crawford, G. B.; Thompson, R. E.


    Masking material and a thickening agent preserve limited unanodized areas when aluminum surfaces are anodized with chromic acid. For protection of large areas it combines well with a certain self-adhesive plastic tape.

  10. Nablus mask-like facial syndrome

    DEFF Research Database (Denmark)

    Allanson, Judith; Smith, Amanda; Hare, Heather


    Nablus mask-like facial syndrome (NMLFS) has many distinctive phenotypic features, particularly tight glistening skin with reduced facial expression, blepharophimosis, telecanthus, bulky nasal tip, abnormal external ear architecture, upswept frontal hairline, and sparse eyebrows. Over the last fe...

  11. Resonant Effects in Nanoscale Bowtie Apertures (United States)

    Ding, Li; Qin, Jin; Guo, Songpo; Liu, Tao; Kinzel, Edward; Wang, Liang


    Nanoscale bowtie aperture antennas can be used to focus light well below the diffraction limit with extremely high transmission efficiencies. This paper studies the spectral dependence of the transmission through nanoscale bowtie apertures defined in a silver film. A realistic bowtie aperture is numerically modeled using the Finite Difference Time Domain (FDTD) method. Results show that the transmission spectrum is dominated by Fabry-Pérot (F-P) waveguide modes and plasmonic modes. The F-P resonance is sensitive to the thickness of the film and the plasmonic resonant mode is closely related to the gap distance of the bowtie aperture. Both characteristics significantly affect the transmission spectrum. To verify these numerical results, bowtie apertures are FIB milled in a silver film. Experimental transmission measurements agree with simulation data. Based on this result, nanoscale bowtie apertures can be optimized to realize deep sub-wavelength confinement with high transmission efficiency with applications to nanolithography, data storage, and bio-chemical sensing. PMID:27250995

  12. Nanostructure Secondary-Mirror Apodizing Mask for Transmitter Signal Suppression in a Duplex Telescope (United States)

    Hagopian, John; Livas, Jeffrey; Shiri, Shahram; Getty, Stephanie; Tveekrem, June; Butler, James


    A document discusses a nanostructure apodizing mask, made of multi-walled carbon nanotubes, that is applied to the centers (or in and around the holes) of the secondary mirrors of telescopes that are used to interferometrically measure the strain of space-time in response to gravitational waves. The shape of this ultra-black mask can be adjusted to provide a smooth transition to the clear aperture of the secondary mirror to minimize diffracted light. Carbon nanotubes grown on silicon are a viable telescope mirror substrate, and can absorb significantly more light than other black treatments. The hemispherical reflectance of multi-walled carbon nanotubes grown at GSFC is approximately 3 to 10 times better than a standard aerospace paint used for stray light control. At the LISA (Laser Interferometer Space Antenna) wavelength of 1 micron, the advantage over paint is a factor of 10. Primarily, in the center of the secondary mirror (in the region of central obscuration, where no received light is lost) a black mask is applied to absorb transmitted light that could be reflected back into the receiver. In the LISA telescope, this is in the center couple of millimeters. The shape of this absorber is critical to suppress diffraction at the edge. By using the correct shape, the stray light can be reduced by approximately 10 to the 9 orders of magnitude versus no center mask. The effect of the nanotubes has been simulated in a stray-light model. The effect of the apodizing mask has been simulated in a near-field diffraction model. Specifications are geometry-dependent, but the baseline design for the LISA telescope has been modeled as well. The coatings are somewhat fragile, but work is continuing to enhance adhesion.

  13. Role of mask in asian shamanism




    In the article there is considered a phenomena of shamanism as a cultural universal. Analysis object is a clay mask of National Museum of the Republic of Kazakhstan. It was found in Keder settlement (Kuiryktobe), located in Otrar Oasis at one of the most busy part of the Silk Road. The mask as shamanistic ritual attribute is considered as an obligatory condition for meditative function of shaman.

  14. Optical interferometry for biology and medicine

    CERN Document Server

    Nolte, David D


    This book presents the fundamental physics of optical interferometry as applied to biophysical, biological and medical research. Interference is at the core of many types of optical detection and is a powerful probe of cellular and tissue structure in interfererence microscopy and in optical coherence tomography. It is also the root cause of speckle and other imaging artefacts that limit range and resolution. For biosensor applications, the inherent sensitivity of interferometry enables ultrasensitive detection of molecules in biological samples for medical diagnostics. In this book, emphasis is placed on the physics of light scattering, beginning with the molecular origins of refraction as light propagates through matter, and then treating the stochastic nature of random fields that ultimately dominate optical imaging in cells and tissue. The physics of partial coherence plays a central role in the text, with a focus on coherence detection techniques that allow information to be selectively detected out of ...

  15. A New Neutron Interferometry Facility at NCNR (United States)

    Shahi, Chandra; Wietfeldt, Fred; Huber, Michael; Pushin, Dmitry; Arif, Muhammad


    A neutron interferometer splits an incoming neutron beam into two coherent partial beams, which travel on different paths and then recombine to form an interference pattern. This pattern is used to precisely determine the phase shift of a sample in one of the paths, thus the neutron interaction potential in the sample can be measured with high precision. A new neutron interferometry setup (NIOFa) has been constructed at the NIST Center for Neutron Research (NCNR). This new facility is mainly focused on spin based interferometry, which will expand its applications in both quantum computation and material research. New spin-control mechanisms are being tested; including thin-film spin flippers and efficient polarizing double cavity super mirrors. Doubling the neutron's degrees of freedom inside the interferometer promises exciting new quantum mechanical experiments and research capabilities. This work is supported by the National Science Foundation.

  16. Joint Multi-baseline SAR Interferometry

    Directory of Open Access Journals (Sweden)

    S. Tebaldini


    Full Text Available We propose a technique to provide interferometry by combining multiple images of the same area. This technique differs from the multi-baseline approach in literature as (a it exploits all the images simultaneously, (b it performs a spectral shift preprocessing to remove most of the decorrelation, and (c it exploits distributed targets. The technique is mainly intended for DEM generation at centimetric accuracy, as well as for differential interferometry. The problem is framed in the contest of single-input multiple-output (SIMO channel estimation via the cross-relations (CR technique and the resulting algorithm provides significant improvements with respect to conventional approaches based either on independent analysis of single interferograms or multi-baselines phase analysis of single pixels of current literature, for those targets that are correlated in all the images, like for long-term coherent areas, or for acquisitions taken with a short revisit time (as those gathered with future satellite constellations.

  17. Time-average dynamic speckle interferometry (United States)

    Vladimirov, A. P.


    For the study of microscopic processes occurring at structural level in solids and thin biological objects, a method of dynamic speckle interferometry successfully applied. However, the method has disadvantages. The purpose of the report is to acquaint colleagues with the method of averaging in time in dynamic speckle - interferometry of microscopic processes, allowing eliminating shortcomings. The main idea of the method is the choice the averaging time, which exceeds the characteristic time correlation (relaxation) the most rapid process. The method theory for a thin phase and the reflecting object is given. The results of the experiment on the high-cycle fatigue of steel and experiment to estimate the biological activity of a monolayer of cells, cultivated on a transparent substrate is given. It is shown that the method allows real-time visualize the accumulation of fatigue damages and reliably estimate the activity of cells with viruses and without viruses.

  18. Freeform metrology using subaperture stitching interferometry (United States)

    Supranowitz, Chris; Lormeau, Jean-Pierre; Maloney, Chris; Murphy, Paul; Dumas, Paul


    As applications for freeform optics continue to grow, the need for high-precision metrology is becoming more of a necessity. Currently, coordinate measuring machines (CMM) that implement touch probes or optical probes can measure the widest ranges of shapes of freeform optics, but these measurement solutions often lack sufficient lateral resolution and accuracy. Subaperture stitching interferometry (SSI™) extends traditional Fizeau interferometry to provide accurate, high-resolution measurements of flats, spheres, and aspheres, and development is currently on-going to enable measurements of freeform surfaces. We will present recent freeform metrology results, including repeatability and cross-test data. We will also present MRF® polishing results where the stitched data was used as the input "hitmap" to the deterministic polishing process.

  19. Kinetic titration series with biolayer interferometry. (United States)

    Frenzel, Daniel; Willbold, Dieter


    Biolayer interferometry is a method to analyze protein interactions in real-time. In this study, we illustrate the usefulness to quantitatively analyze high affinity protein ligand interactions employing a kinetic titration series for characterizing the interactions between two pairs of interaction patterns, in particular immunoglobulin G and protein G B1 as well as scFv IC16 and amyloid beta (1-42). Kinetic titration series are commonly used in surface plasmon resonance and involve sequential injections of analyte over a desired concentration range on a single ligand coated sensor chip without waiting for complete dissociation between the injections. We show that applying this method to biolayer interferometry is straightforward and i) circumvents problems in data evaluation caused by unavoidable sensor differences, ii) saves resources and iii) increases throughput if screening a multitude of different analyte/ligand combinations.

  20. Kinetic titration series with biolayer interferometry.

    Directory of Open Access Journals (Sweden)

    Daniel Frenzel

    Full Text Available Biolayer interferometry is a method to analyze protein interactions in real-time. In this study, we illustrate the usefulness to quantitatively analyze high affinity protein ligand interactions employing a kinetic titration series for characterizing the interactions between two pairs of interaction patterns, in particular immunoglobulin G and protein G B1 as well as scFv IC16 and amyloid beta (1-42. Kinetic titration series are commonly used in surface plasmon resonance and involve sequential injections of analyte over a desired concentration range on a single ligand coated sensor chip without waiting for complete dissociation between the injections. We show that applying this method to biolayer interferometry is straightforward and i circumvents problems in data evaluation caused by unavoidable sensor differences, ii saves resources and iii increases throughput if screening a multitude of different analyte/ligand combinations.

  1. Towards the Intensity Interferometry Stellar Imaging System

    CERN Document Server

    Daniel, M; Dravins, D; Kieda, D; Le Bohec, S; Núñez, P; Ribak, E


    The imminent availability of large arrays of large light collectors deployed to exploit atmospheric Cherenkov radiation for gamma-ray astronomy at more than 100GeV, motivates the growing interest in application of intensity interferometry in astronomy. Indeed, planned arrays numbering up to one hundred telescopes will offer close to 5,000 baselines, ranging from less than 50m to more than 1000m. Recent and continuing signal processing technology developments reinforce this interest. Revisiting Stellar Intensity Interferometry for imaging is well motivated scientifically. It will fill the short wavelength (B/V bands) and high angular resolution (< 0.1mas) gap left open by amplitude interferometers. It would also constitute a first and important step toward exploiting quantum optics for astronomical observations, thus leading the way for future observatories. In this paper we outline science cases, technical approaches and schedule for an intensity interferometer to be constructed and operated in the visible...

  2. Nanoscale optical interferometry with incoherent light (United States)

    Li, Dongfang; Feng, Jing; Pacifici, Domenico


    Optical interferometry has empowered an impressive variety of biosensing and medical imaging techniques. A widely held assumption is that devices based on optical interferometry require coherent light to generate a precise optical signature in response to an analyte. Here we disprove that assumption. By directly embedding light emitters into subwavelength cavities of plasmonic interferometers, we demonstrate coherent generation of surface plasmons even when light with extremely low degrees of spatial and temporal coherence is employed. This surprising finding enables novel sensor designs with cheaper and smaller light sources, and consequently increases accessibility to a variety of analytes, such as biomarkers in physiological fluids, or even airborne nanoparticles. Furthermore, these nanosensors can now be arranged along open detection surfaces, and in dense arrays, accelerating the rate of parallel target screening used in drug discovery, among other high volume and high sensitivity applications. PMID:26880171

  3. Permafrost Active Layer Seismic Interferometry Experiment (PALSIE).

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, Robert [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Knox, Hunter Anne [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); James, Stephanie [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lee, Rebekah [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cole, Chris [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)


    We present findings from a novel field experiment conducted at Poker Flat Research Range in Fairbanks, Alaska that was designed to monitor changes in active layer thickness in real time. Results are derived primarily from seismic data streaming from seven Nanometric Trillium Posthole seismometers directly buried in the upper section of the permafrost. The data were evaluated using two analysis methods: Horizontal to Vertical Spectral Ratio (HVSR) and ambient noise seismic interferometry. Results from the HVSR conclusively illustrated the method's effectiveness at determining the active layer's thickness with a single station. Investigations with the multi-station method (ambient noise seismic interferometry) are continuing at the University of Florida and have not yet conclusively determined active layer thickness changes. Further work continues with the Bureau of Land Management (BLM) to determine if the ground based measurements can constrain satellite imagery, which provide measurements on a much larger spatial scale.

  4. Predicting polarization performance of high-numerical aperture inspection lenses (United States)

    Fahr, Stephan; Werschnik, Jan; Bening, Matthias; Uhlendorf, Kristina


    Along the course of increasing through-put and improving signal to noise ratio in optical wafer and mask inspection, demands on wave front aberrations and polarization characteristics are ever increasing. The system engineers and optical designers involved in the development of such optical systems will be responsible for specifying the quality of the optical material and the mechanical tolerances. Among optical designers it is well established how to estimate the wave front error of assembled and adjusted optical devices via sensitivity or Monte-Carlo analysis. However, when compared with the scalar problem of wave front estimation, the field of polarization control deems to pose a more complex problem due to its vectorial nature. Here we show our latest results in how to model polarization affecting aspects. In the realm of high numerical aperture (NA) inspection optics we will focus on the impact of coatings, stress induced birefringence due to non-perfect lens mounting, and finally the birefringence of the optical material. With all these tools at hand, we have a more complete understanding of the optical performance of our assembled optical systems. Moreover, we are able to coherently develop optical systems meeting demanding wave front criteria as well as high end polarization specifications.

  5. No masking between test and mask components in perceptually different depth planes. (United States)

    Hibbeler, Patrick J; Olzak, Lynn A


    2-D cues to perceived depth organization have been used to segregate test and mask stimulus components in a discrimination task. Observers made either spatial-frequency or orientation judgments on a rectangular test component by itself or in the presence of constant rectangular masks. There were two basic masking conditions: same-plane or different-plane. In the same-plane conditions, the test components and masks are perceived as existing in the same depth plane. In the different-plane conditions, the test and mask components are perceived to exist in different depth planes. The perception of different depth planes was achieved by using perceived occlusion, which could place either component closer or further from the observer. The results suggest that when test and mask components are separated into different depth planes they no longer influence one another. This effect could be observed in either depth organization, test components in front of the masks or mask components in front of the test. These results indicate that the figure-ground organization of components is not important. Only the designation as existing in the same or different depth planes affects whether or not a mask is effective.

  6. Masked Uncontrolled Hypertension in CKD. (United States)

    Agarwal, Rajiv; Pappas, Maria K; Sinha, Arjun D


    Masked uncontrolled hypertension (MUCH) is diagnosed in patients treated for hypertension who are normotensive in the clinic but hypertensive outside. In this study of 333 veterans with CKD, we prospectively evaluated the prevalence of MUCH as determined by ambulatory BP monitoring using three definitions of hypertension (daytime hypertension ≥135/85 mmHg; either nighttime hypertension ≥120/70 mmHg or daytime hypertension; and 24-hour hypertension ≥130/80 mmHg) or by home BP monitoring (hypertension ≥135/85 mmHg). The prevalence of MUCH was 26.7% by daytime ambulatory BP, 32.8% by 24-hour ambulatory BP, 56.1% by daytime or night-time ambulatory BP, and 50.8% by home BP. To assess the reproducibility of the diagnosis, we repeated these measurements after 4 weeks. Agreement in MUCH diagnosis by ambulatory BP was 75-78% (κ coefficient for agreement, 0.44-0.51), depending on the definition used. In contrast, home BP showed an agreement of only 63% and a κ coefficient of 0.25. Prevalence of MUCH increased with increasing clinic systolic BP: 2% in the 90-110 mmHg group, 17% in the 110-119 mmHg group, 34% in the 120-129 mmHg group, and 66% in the 130-139 mmHg group. Clinic BP was a good determinant of MUCH (receiver operating characteristic area under the curve 0.82; 95% confidence interval 0.76-0.87). In diagnosing MUCH, home BP was not different from clinic BP. In conclusion, among people with CKD, MUCH is common and reproducible, and should be suspected when clinic BP is in the prehypertensive range. Confirmation of MUCH diagnosis should rely on ambulatory BP monitoring.

  7. Uncertainty and confusion in temporal masking (United States)

    Formby, C.; Zhang, T.


    In a landmark study, Wright et al. [Nature 387, 176-178 (1997)] reported an apparent backward-masking deficit in language-impaired children. Subsequently, these controversial results have been influential in guiding treatments for childhood language problems. In this study we revisited Wright et al.'s temporal-masking paradigm to evaluate listener uncertainty effects. Masked detection was measured for 20-ms sinusoids (480, 1000, or 1680 Hz) presented at temporal positions before, during, or after a gated narrowband (W=600-1400 Hz) masker. Listener uncertainty was investigated by cueing various stimulus temporal properties with a 6000-Hz sinusoid presented either ipsi- or contra-lateral to the test ear or bilaterally. The primary cueing effect was measured in the backward-masking condition for a contralateral cue gated simultaneously with the on-frequency 1000-Hz signal. The resulting cued masked-detection threshold was reduced to quiet threshold. No significant cueing effects were obtained for other signal temporal positions in the masker nor for any off-frequency signal conditions. These results indicate that (1) uncertainty can be reduced or eliminated for on-frequency backward masking by cueing the signal and (2) the deficit reported by Wright et al. for language-impaired children may reflect uncertainty and confusion rather than a temporal-processing deficit per se. [Research supported by NIDCD.

  8. VSP wave separation by adaptive masking filters (United States)

    Rao, Ying; Wang, Yanghua


    In vertical seismic profiling (VSP) data processing, the first step might be to separate the down-going wavefield from the up-going wavefield. When using a masking filter for VSP wave separation, there are difficulties associated with two termination ends of the up-going waves. A critical challenge is how the masking filter can restore the energy tails, the edge effect associated with these terminations uniquely exist in VSP data. An effective strategy is to implement masking filters in both τ-p and f-k domain sequentially. Meanwhile it uses a median filter, producing a clean but smooth version of the down-going wavefield, used as a reference data set for designing the masking filter. The masking filter is implemented adaptively and iteratively, gradually restoring the energy tails cut-out by any surgical mute. While the τ-p and the f-k domain masking filters target different depth ranges of VSP, this combination strategy can accurately perform in wave separation from field VSP data.

  9. Claude Levi-Strauss: Mask and Myth

    Directory of Open Access Journals (Sweden)

    Senka Kovač


    Full Text Available This paper discuss a relationship between mask and myth and how the appropriate analysis by Claude Levi-Strauss may make clearer a complex field of masks in the part of North America. Claude Levi-Strauss stressed the multi- layered character of myth structure. Similar multi-layered character can be seen at the level of expression, content and meaning of Salish, Kwakiutl and other unique masks of this part of North America. Claude Levi-Strauss analysed certain myths trying to explain ‘the path’ of the masks that belong to the people with similar languages, or those who lived nearby. The mythology of Tsimshian, Tlingit and Haïda people have certain common characteristics that point to the similarities with the nearby groups (Kwakiutl. Despite differences that exist at the level of meanings of the masks, there is also common ‘mythological heritage’ of the people who used to live in the Northern Pacific Coast. Claude Levi-Strauss showed that there is no final solution in the myth analysis, and that there is no possibility that the dissection of the problem will reveal some hidden unity. "As mythical though does not want to start clearly somewhere and come somewhere, it never goes through its whole trajectory: there is always something waiting to be fullfield. The same way as rituals, myths are infinite." It seems that Levi-Strauss explanation of the Path of masks goes in that direction.

  10. Phase mask coronagraphy at JPL and Palomar

    Directory of Open Access Journals (Sweden)

    Serabyn E.


    Full Text Available For the imaging of faint companions, phase mask coronagraphy has the dual advantages of a small inner working angle and high throughput. This paper summarizes our recent work in developing phase masks and in demonstrating their capabilities at JPL. Four-quadrant phase masks have been manufactured at JPL by means of both evaporation and etching, and we have been developing liquid crystal vortex phase masks in partnership with a commercial vendor. Both types of mask have been used with our extreme adaptive optics well-corrected subaperture at Palomar to detect known brown dwarf companions as close as ~ 2.5 λ/D to stars. Moreover, our recent vortex masks perform very well in laboratory tests, with a demonstrated infrared contrast of about 10−6 at 3 λ/D, and contrasts of a few 10−7 with an initial optical wavelength device. The demonstrated performance already meets the needs of ground-based extreme adaptive optics coronagraphy, and further planned improvements are aimed at reaching the 10−10 contrast needed for terrestrial exoplanet detection with a space-based coronagraph.

  11. Measuring Close Binary Stars with Speckle Interferometry (United States)


    telescope has access to an adaptive optics system, and those telescopes utilize a prior method developed in 1970 by Antoine Labeyrie [2]. This method...23019+4220. a) b) c) 3. SPECKLE INTERFEROMETRY In 1970, Antoine Labeyrie [2] developed a technique to detect double stars that are closer than the...resulting in a simple product of cosine squared with no additive constant . The effects of a non- zero additive constant will become apparent in section 5

  12. Lateral shear interferometry with holo shear lens (United States)

    Joenathan, C.; Mohanty, R. K.; Sirohi, R. S.


    A simple method for obtaining lateral shear using holo shear lenses (HSL) has been discussed. This simple device which produces lateral shears in the orthogonal directions has been used for lens testing. The holo shear lens is placed at or near the focus of the lens to be tested. It has also been shown that HSL can be used in speckle shear interferometry as it performs both the functions of shearing and imaging.

  13. Large momentum beamsplitting in atom interferometry

    Institute of Scientific and Technical Information of China (English)

    G; D; McDonald; P; M; anju; P; B; Wigley; P; J; Everitt; WEI; Chunhua; M; A; Sooriyabandara; M; Boozarjmehr; A; Kordbacheh; C; Quinlivan; C; N; Kuhn; J; E; Debs; K; S; Hardman; N; P; Robins


    Large momentum transfer( LM T) beamsplitting in atom interferometry is review ed,focusing on the use of Bloch Oscillations to achieve high momentum separation w ithout loss of visibility. Phase sensitivity w ith a fringe visibility of 7% is observed in a horizontally guided,acceleration-sensitive atom interferometer w ith a momentum separation of 80k betw een its arms.In addition,a 510 k beamsplitter is demonstrated.

  14. Fundamental Stellar Properties from Optical Interferometry

    CERN Document Server

    van Belle, Gerard T; Boyajian, Tabetha; Harper, Graham; Hummel, Christian; Pedretti, Ettore; Baines, Ellyn; White, Russel; Ravi, Vikram; Ridgway, Steve


    High-resolution observations by visible and near-infrared interferometers of both single stars and binaries have made significant contributions to the foundations that underpin many aspects of our knowledge of stellar structure and evolution for cool stars. The CS16 splinter on this topic reviewed contributions of optical interferometry to date, examined highlights of current research, and identified areas for contributions with new observational constraints in the near future.

  15. Gravitational wave detection using atom interferometry (United States)

    Hogan, Jason


    The advent of gravitational wave astronomy promises to provide a new window into the universe. Low frequency gravitational waves below 10 Hz are expected to offer rich science opportunities both in astrophysics and cosmology, complementary to signals in LIGO's band. Detector designs based on atom interferometry have a number of advantages over traditional approaches in this band, including the possibility of substantially reduced antenna baseline length in space and high isolation from seismic noise for a terrestrial detector. In particular, atom interferometry based on the clock transition in group II atoms offers tantalizing new possibilities. Such a design is expected to be highly immune to laser frequency noise because the signal arises strictly from the light propagation time between two ensembles of atoms. This would allow for a gravitational wave detector with a single linear baseline, potentially offering advantages in cost and design flexibility. In support of these proposals, recent progress in long baseline atom interferometry in a 10-meter drop tower has enabled observation of matter wave interference with atomic wavepacket separations exceeding 50 cm and interferometer durations of more than 2 seconds. This approach can provide ground-based proof-of-concept demonstrations of many of the technical requirements of both terrestrial and satellite gravitational wave detectors.

  16. GPS radio interferometry of travelling ionospheric disturbances (United States)

    Afraimovich, E. L.; Palamartchouk, K. S.; Perevalova, N. P.


    This paper presents some results investigating the new possibilities of radio interferometry of Travelling Ionospheric Disturbances (TIDs) that are based on exploiting standard measurements of transionospheric radio signal characteristics and coordinate-time measurements using dual-frequency multichannel receivers of the Global Positioning System (GPS). A Statistical Angle-of-arrival and Doppler Method for GPS radio interferometry (SADM-GPS) is proposed for determining the characteristics of the TIDs dynamics by measuring variations of GPS phase derivatives with respect to time and spatial coordinates. These data are used to calculate corresponding values of the velocity vector, in view of a correction for satellite motions based on the current information available regarding the angular coordinates of the satellites. Subsequently, velocity and direction distributions are constructed and analyzed to verify the hypothesis of whether there is a predominant displacement. If it exists, then the pattern can be considered to be travelling, and the mean travel velocity can be determined from the velocity distribution. Through a computer simulation it was shown that multi-satellite GPS radio interferometry in conjunction with the SADM-GPS algorithm allows the detection and measurement of the velocity vector of TIDs in virtually the entire azimuthal range of possible TID propagation directions. The use of the proposed method is exemplified by an investigation of TIDs during the solar eclipse of 9 March 1997, using the GPS-radio interferometer GPSINT at Irkutsk.

  17. Interferometry and synthesis in radio astronomy

    CERN Document Server

    Thompson, A Richard; Swenson Jr , George W


    This book is open access under a CC BY-NC 4.0 license. The third edition of this indispensable book in radio interferometry provides extensive updates to the second edition, including results and technical advances from the past decade; discussion of arrays that now span the full range of the radio part of the electromagnetic spectrum observable from the ground, 10 MHz to 1 THz; an analysis of factors that affect array speed; and an expanded discussion of digital signal-processing techniques and of scintillation phenomena and the effects of atmospheric water vapor on image distortion, among many other topics. With its comprehensiveness and detailed exposition of all aspects of the theory and practice of radio interferometry and synthesis imaging, this book has established itself as a standard reference in the field. It begins with an overview of the basic principles of radio astronomy, a short history of the development of radio interferometry, and an elementary discussion of the operation of an interferomete...

  18. Holographic Interferometry Applications In External Osteosynthesis (United States)

    Jacquot, P.; Rastogi, P. K.; Pflug, L.


    In order to maintain fragments of fractured bones in a state of immobilization, the use of an external rigid frame has proved to be very advantageous. Confronted by contradictory requirements, the conception of external fixation has, however, been a difficult task. The present paper aims to show, through three examples of varied bearings, the interest of holographic interferometry in external osteosynthesis. The first example deals with the mechanical behavior of a key element of the fixation device the ball joint submitted to realistic loads. The last two examples compare two models of ball joints as to their characteristics of rigidity and of resistance to slipping. Whereas in the former case holographic interferometry primarily fulfills the function of a prelude to the modelization work, in the latter cases it serves to formulate an engineering diagnostic. The findings relate to the remarkable elastic behavior of the ball joint, to the effectiveness of a lightened bowl design, and to the fact that cousin models may behave quite differently as to their resistance to slipping rotations of the bar. In comparison with other experimental methods, holographic interferometry appears to be very competitive and result-oriented and, as such, is expected to multiply applications in similar evaluation tasks.

  19. Holographic interferometry for security and forensic applications (United States)

    Ambadiyil, Sajan; R. C., Sreelekshmi; Mahadevan Pillai, V. P.; Prabhu, Radhakrishna


    Security holograms having unique 3D images are one of the tools for enhancing the security for product and personnel authentication and anti-counterfeiting. Apart from the high technology that is required, the uniqueness of a 3D object presents a significant additional threshold for the counterfeiting of such security holograms. But, due to the development of 3D printing technology, the hurdles are disabled and allow the chances of counterfeiting. In order to overcome this, holographic interferometry is effectively utilized and the object is recorded twice before and after the state of random object change. At the time of reconstruction, two signal waves generated simultaneously interfere each other, resulting in a fringe modulation. This fringe modulation in 3D image hologram with respect to the random object change is exploited to generate a rigid and unique anticounterfeit feature. Though holographic interferometry techniques are being widely used for the non-destructive evaluation, the applicability of this technology for the security and forensic activity is less exploited. This paper describes our efforts to introduce holographic interferometry in 3D image holograms for security and forensic applications.

  20. Comparing Laser Interferometry and Atom Interferometry Approaches to Space-Based Gravitational-Wave Measurement (United States)

    Baker, John; Thorpe, Ira


    Thoroughly studied classic space-based gravitational-wave missions concepts such as the Laser Interferometer Space Antenna (LISA) are based on laser-interferometry techniques. Ongoing developments in atom-interferometry techniques have spurred recently proposed alternative mission concepts. These different approaches can be understood on a common footing. We present an comparative analysis of how each type of instrument responds to some of the noise sources which may limiting gravitational-wave mission concepts. Sensitivity to laser frequency instability is essentially the same for either approach. Spacecraft acceleration reference stability sensitivities are different, allowing smaller spacecraft separations in the atom interferometry approach, but acceleration noise requirements are nonetheless similar. Each approach has distinct additional measurement noise issues.

  1. Clean induced feature CD shift of EUV mask (United States)

    Nesládek, Pavel; Schedel, Thorsten; Bender, Markus


    EUV developed in the last decade to the most promising Second contributor is the fact that EUV mask is currently in contrary to optical mask not yet equipped with sealed pellicle, leading to much higher risk of mask contamination. Third reason is use of EUV mask in vacuum, possibly leading to deposition of vacuum contaminants on the EUV mask surface. Latter reason in combination with tight requirements on backside cleanliness lead to the request of frequent recleaning of the EUV mask, in order to sustain mask lifetime similar to that of optical mask. Mask cleaning process alters slightly the surface of any mask - binary COG mask, as well as phase shift mask of any type and naturally also of the EUV mask as well. In case of optical masks the changes are almost negligible, as the mask is exposed to max. 10-20 re-cleans within its life time. These modifications can be expressed in terms of different specified parameters, e.g. CD shift, phase/trans shift, change of the surface roughness etc. The CD shift, expressed as thinning (or exceptionally thickening) of the dark features on the mask is typically in order of magnitude 0.1nm per process run, which is completely acceptable for optical mask. Projected on the lifetime of EUV mask, assuming 100 clean process cycles, this will lead to CD change of about 10nm. For this reason the requirements for EUV mask cleaning are significantly tighter, << 0.1 nm per process run. This task will look even more challenging, when considering, that the tools for CD measurement at the EUV mask are identical as for optical mask. There is one aspect influencing the CD shift, which demands attention. The mask composition of the EUV mask is significantly different from the optical mask. More precisely there are 2 materials influencing the estimated CD in case of EUV mask, whereas there is one material only in case of optical masks, in first approximation. For optical masks, the CD changes can be attributed to modification of the absorber

  2. Optical inspection of EPL stencil masks (United States)

    Lee, Po-Tung; Engelstad, Roxann L.; Lovell, Edward G.; Kawata, Shintaro; Hirayanagi, Noriyuki; Sogard, Michael R.


    We are now at a major junction in lithography where non-optical lithographies, such as Electron Projection Lithography (EPL) [1], are being introduced. The mask used in EPL is a non-transparent silicon substrate with a thin silicon (~2μm) membrane with openings for electrons to pass through acting as a scatterer. This must be inspected as defects may cause printable defects. Initial mask inspection work has used SEM inspection to find these defects. However, we have historically used optical mask inspection tools, utilising wavelengths at or above what we are using for imaging, to qualify masks. This technology has been increasingly difficult to sustain as we have moved from imaging using mercury lamp based sources to pulsed excimer laser based sources that are not very suited to the inspection imaging. Indeed, review of defects found has moved from optical microscopes to SEM based tools. Inspection tools have also evolved, with the first SEM based mask inspection tools being developed to find the smallest defects, however these have the penalty of very low throughput. We will show the potential of using optical systems for the transmissive inspection of these EPL masks. The high potential of existing tools will be shown together with the need for a next generation of inspection tools. We will show that simulations indicate that an inspection source with 193nm wavelength would be required for the detection of 50nm defects on a mask used to print 70nm dense lines. It will also be shown how the position of the defect within the membrane greatly influences detection as well as the implications of moving to a thinner silicon membrane.

  3. Optimizing the Search for High-z GRBs: The JANUS X-ray Coded Aperture Telescope

    CERN Document Server

    Burrows, D N; Palmer, D; Romano, P; Mangano, V; La Parola, V; Falcone, A D; Roming, P W A


    We discuss the optimization of gamma-ray burst (GRB) detectors with a goal of maximizing the detected number of bright high-redshift GRBs, in the context of design studies conducted for the X-ray transient detector on the JANUS mission. We conclude that the optimal energy band for detection of high-z GRBs is below about 30 keV. We considered both lobster-eye and coded aperture designs operating in this energy band. Within the available mass and power constraints, we found that the coded aperture mask was preferred for the detection of high-z bursts with bright enough afterglows to probe galaxies in the era of the Cosmic Dawn. This initial conclusion was confirmed through detailed mission simulations that found that the selected design (an X-ray Coded Aperture Telescope) would detect four times as many bright, high-z GRBs as the lobster-eye design we considered. The JANUS XCAT instrument will detect 48 GRBs with z > 5 and fluence Sx > 3 {\\times} 10-7 erg cm-2 in a two year mission.

  4. Validation of burst overlapping for ALOS-2 PALSAR-2 ScanSAR-ScanSAR interferometry (United States)

    Natsuaki, Ryo; Motohka, Takeshi; Ohki, Masato; Watanabe, Manabu; Suzuki, Shinichi


    The Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) aboard the Advanced Land Observing Satellite- 2 (ALOS-2, "DAICHI-2") is the latest L-band spaceborne synthetic aperture radar (SAR). PALSAR-2 observes the world mainly with 10 m resolution / 70 km swath Stripmap mode and 25 m resolution / 350 km swath ScanSAR mode. The 3-m resolution Stripmap mode is mainly used upon Japan. 350 km ScanSAR observation could detect large scale deformation e.g., the Mw 7.8 Gorkha, Nepal earthquake and its aftershocks in 2015. ALOS-2 ScanSAR is the first one that supports ScanSAR-ScanSAR interferometry in L-band spaceborne SAR. However, because of the parameter setting error for the orbit estimation, ALOS-2 PALSAR-2 ScanSAR could achieve little number of interferometric pair until the software modification on February 8, 2015. That is, the burst overlap timing required for the interferometric analysis was insufficient and it depends on the observation date. In this paper, we report the investigation results of this case and discuss the current status of the ALOS-2 ScanSAR InSAR. Some archives achieved before February 8, 2015 can be used for interferometric analysis with after Feb. 8. However, most of them have no interferometric pair. We also report that the archives acquired after February 8, have enough burst overlapping.

  5. An etching mask and a method to produce an etching mask

    DEFF Research Database (Denmark)


    The present invention relates to an etching mask comprising silicon containing block copolymers produced by self-assembly techniques onto silicon or graphene substrate. Through the use of the etching mask, nanostructures having long linear features having sub-10 nm width can be produced....

  6. The Intervenor Effect in Masked Priming: How Does Masked Priming Survive across an Intervening Word? (United States)

    Forster, Kenneth I.


    Four masked priming experiments are reported investigating the effect of inserting an unrelated word between the masked prime and the target. When the intervening word is visible, identity priming is reduced to the level of one-letter-different form priming, but form priming is largely unaffected. However, when the intervening word is itself…

  7. Aperture effects in squid jet propulsion. (United States)

    Staaf, Danna J; Gilly, William F; Denny, Mark W


    Squid are the largest jet propellers in nature as adults, but as paralarvae they are some of the smallest, faced with the inherent inefficiency of jet propulsion at a low Reynolds number. In this study we describe the behavior and kinematics of locomotion in 1 mm paralarvae of Dosidicus gigas, the smallest squid yet studied. They swim with hop-and-sink behavior and can engage in fast jets by reducing the size of the mantle aperture during the contraction phase of a jetting cycle. We go on to explore the general effects of a variable mantle and funnel aperture in a theoretical model of jet propulsion scaled from the smallest (1 mm mantle length) to the largest (3 m) squid. Aperture reduction during mantle contraction increases propulsive efficiency at all squid sizes, although 1 mm squid still suffer from low efficiency (20%) because of a limited speed of contraction. Efficiency increases to a peak of 40% for 1 cm squid, then slowly declines. Squid larger than 6 cm must either reduce contraction speed or increase aperture size to maintain stress within maximal muscle tolerance. Ecological pressure to maintain maximum velocity may lead them to increase aperture size, which reduces efficiency. This effect might be ameliorated by nonaxial flow during the refill phase of the cycle. Our model's predictions highlight areas for future empirical work, and emphasize the existence of complex behavioral options for maximizing efficiency at both very small and large sizes.

  8. Asymmetric masks for large field-of-view and high-energy X-ray phase contrast imaging (United States)

    Endrizzi, M.; Astolfo, A.; Price, B.; Haig, I.; Olivo, A.


    We report on a large field of view, laboratory-based X-ray phase-contrast imaging setup. The method is based upon the asymmetric mask design that enables the retrieval of the absorption, refraction and scattering properties of the sample without the need to move any component of the imaging system. This can be thought of as a periodic repetition of a group of three (or more) apertures arranged in such a way that each laminar beam, defined by the apertures, produces a different illumination level when analysed with a standard periodic set of apertures. The sample is scanned through the imaging system, also removing possible aliasing problems that might arise from partial sample illumination when using the edge illumination technique. This approach preserves the incoherence and achromatic properties of edge illumination, removes the problems related to aliasing and it naturally adapts to those situations in clinical, industrial and security imaging where the image is acquired by scanning the sample relative to the imaging system. These concepts were implemented for a large field-of-view set of masks (20 cm × 1.5 cm and 15 cm × 1.2 cm), designed to work with a tungsten anode X-ray source operated up to 80-100 kVp, from which preliminary experimental results are presented.

  9. Theoretical and Numerical Analyses of a Slit-Masked Chicane for Modulated Bunch Generation

    CERN Document Server

    Zhu, Xiaofang; Shin, Young-Min


    Density modulations on electron beams can improve machine performance of beam-driven accelerators and FELs with resonance beam-wave coupling. The beam modulation is studied with a masked chicane by the analytic model and simulations with the beam parameters of the Fermilab Accelerator Science and Technology (FAST) facility. With the chicane design parameters (bending angle of 18{\\deg}, bending radius of 0.95 m and R56 ~ - 0.19 m) and a nominal beam of 3 ps bunch length, the analytic model showed that a slit-mask with slit period 900 {\\mu}m and aperture width 300 {\\mu}m induces a modulation of bunch-to-bunch spacing ~100 {\\mu}m to the bunch with 2.4% correlated energy spread. With the designed slit mask and a 3 ps bunch, particle-in-cell (PIC) simulations, including nonlinear energy distributions, space charge force, and coherent synchrotron radiation (CSR) effect, also result in beam modulation with bunch-to-bunch distance around 100 {\\mu}m and a corresponding modulation frequency of 3 THz. The beam modulatio...

  10. Metrology on phase-shift masks (United States)

    Roeth, Klaus-Dieter; Maurer, Wilhelm; Blaesing-Bangert, Carola


    In the evaluation of new manufacturing processes, metrology is a key function, beginning with the first step of process development through the final step of everyday mass production at the fabrication floor level. RIM-type phase shift masks are expected to be the first application of phase shift masks in high volume production, since they provide improved lithography process capability at the expense of only moderate complexity in their manufacturing. Measurements of critical dimension (CD) and pattern position (overlay) on experimental rim-type and chromeless phase shift masks are reported. Pattern placement (registration) was measured using the Leitz LMS 2000. The overall design and important components were already described. The pattern placement of the RIM type phase shift structures on the photomask described above was determined within a tolerance of 25 nm (3s); nominal accuracy was within 45 nm (3s). On the chromeless phase shift mask the measurement results were easily obtained using a wafer intensity algorithm available with the system. The measurement uncertainties were less than 25 nm and 50 nm for precision and nominal accuracy respectively. The measurement results from the Leitz CD 200 using transmitted light were: a CD- distribution of 135 nm (3s) on a typical 6 micrometers structure all over the mask; the 0.9 micrometers RIM structure had a distribution of 43 nm (3s). Typical long term precision performance values for the CD 200 on both chrome and phase shift structures have been less than 15 nm.

  11. Rapid raw data simulation for fixed-receiver bistatic interferometric synthetic aperture radar (United States)

    Yan, Feifei; Chang, Wenge; Li, Xiangyang


    Raw data simulation of synthetic aperture radar (SAR) is useful for system designing, mission planning, and testing of imaging algorithms. According to the two-dimensional (2-D) frequency spectrum of the fixed-receiver bistatic SAR system, a rapid raw data simulation approach is proposed. With the combination of 2-D inverse Stolt transform in the 2-D frequency domain and phase compensation in the range-Doppler frequency domain, our approach can significantly reduce the simulation time. Therefore, simulations of extended scenes can be performed much more easily. Moreover, the proposed algorithm offers high accuracy of phase distribution, therefore, it can be used for single-pass fixed-receiver bistatic interferometric usage. The proposal is verified by extensive simulations of point targets and extended scene, in which the results indicate the feasibility as well as the effectiveness of our approach. In the end, the accuracy of phase distribution of the proposed algorithm is further examined with simulations of synthetic aperture radar interferometry.

  12. Synthetic aperture tissue and flow ultrasound imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav

    imaging applied to medical ultrasound. It is divided into two major parts: tissue and blood flow imaging. Tissue imaging using synthetic aperture algorithms has been investigated for about two decades, but has not been implemented in medical scanners yet. Among the other reasons, the conventional scanning...... and beamformation methods are adequate for the imaging modalities in clinical use - the B-mode imaging of tissue structures, and the color mapping of blood flow. The acquisition time, however, is too long, and these methods fail to perform real-time three-dimensional scans. The synthetic transmit aperture......, on the other hand, can create a Bmode image with as little as 2 emissions, thus significantly speeding-up the scan procedure. The first part of the dissertation describes the synthetic aperture tissue imaging. It starts with an overview of the efforts previously made by other research groups. A classification...

  13. Solar energy apparatus with apertured shield (United States)

    Collings, Roger J. (Inventor); Bannon, David G. (Inventor)


    A protective apertured shield for use about an inlet to a solar apparatus which includesd a cavity receiver for absorbing concentrated solar energy. A rigid support truss assembly is fixed to the periphery of the inlet and projects radially inwardly therefrom to define a generally central aperture area through which solar radiation can pass into the cavity receiver. A non-structural, laminated blanket is spread over the rigid support truss in such a manner as to define an outer surface area and an inner surface area diverging radially outwardly from the central aperture area toward the periphery of the inlet. The outer surface area faces away from the inlet and the inner surface area faces toward the cavity receiver. The laminated blanket includes at least one layer of material, such as ceramic fiber fabric, having high infra-red emittance and low solar absorption properties, and another layer, such as metallic foil, of low infra-red emittance properties.

  14. Wide Aperture Multipole Magnets of Separator COMBAS

    CERN Document Server

    Artukh, A G; Gridnev, G F; Gruszecki, M; Koscielniak, F; Semchenkova, O V; Sereda, Yu M; Shchepunov, V A; Szmider, J; Teterev, Yu G; Severgin, Yu P; Rozhdestvensky, B V; Myasnikov, Yu A; Shilkin, N F; Lamzin, E A; Nagaenko, M G; Sytchevsky, S E; Vishnevski, I N


    The high-resolving wide aperture separator COMBAS has been designed and commissioned at the FLNR, JINR. Its magneto-optical structure is based on strong focusing principle. The magnetic fields of analysing magnets M_1, M_2, M_7, M_8, contain quadrupole components of alternating sign that provide necessary beam focusing. Besides, all the magnets M_1-M_8, contain sextupole and octupole field components, which minimizes the 2nd and 3rd order aberrations. All this allowed one to increase their apertures, to effectively form a beam of the required sizes, and to decrease the channel length. This implementation of wide aperture magnets with combined functions is unique for the separation technology. Three-components magnetic measurements of all the magnets were performed. The measured data allow reconstructing the 3D-distributions of the fields in all the magnets. 3D-maps are supposed to be used for particle trajectory simulations throughout the entire separator.

  15. Polarimetric SAR interferometry applied to land ice: modeling

    DEFF Research Database (Denmark)

    Dall, Jørgen; Papathanassiou, Konstantinos; Skriver, Henning


    This paper introduces a few simple scattering models intended for the application of polarimetric SAR interfer-ometry to land ice. The principal aim is to eliminate the penetration bias hampering ice sheet elevation maps generated with single-channel SAR interferometry. The polarimetric coherent...

  16. Atom Interferometry for Fundamental Physics and Gravity Measurements in Space (United States)

    Kohel, James M.


    Laser-cooled atoms are used as freefall test masses. The gravitational acceleration on atoms is measured by atom-wave interferometry. The fundamental concept behind atom interferometry is the quantum mechanical particle-wave duality. One can exploit the wave-like nature of atoms to construct an atom interferometer based on matter waves analogous to laser interferometers.

  17. Synthetic aperture radar capabilities in development

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M. [Lawrence Livermore National Lab., CA (United States)


    The Imaging and Detection Program (IDP) within the Laser Program is currently developing an X-band Synthetic Aperture Radar (SAR) to support the Joint US/UK Radar Ocean Imaging Program. The radar system will be mounted in the program`s Airborne Experimental Test-Bed (AETB), where the initial mission is to image ocean surfaces and better understand the physics of low grazing angle backscatter. The Synthetic Aperture Radar presentation will discuss its overall functionality and a brief discussion on the AETB`s capabilities. Vital subsystems including radar, computer, navigation, antenna stabilization, and SAR focusing algorithms will be examined in more detail.

  18. Multi-antenna synthetic aperture radar

    CERN Document Server

    Wang, Wen-Qin


    Synthetic aperture radar (SAR) is a well-known remote sensing technique, but conventional single-antenna SAR is inherently limited by the minimum antenna area constraint. Although there are still technical issues to overcome, multi-antenna SAR offers many benefits, from improved system gain to increased degrees-of-freedom and system flexibility. Multi-Antenna Synthetic Aperture Radar explores the potential and challenges of using multi-antenna SAR in microwave remote sensing applications. These applications include high-resolution imaging, wide-swath remote sensing, ground moving target indica

  19. Communication masking in marine mammals: A review and research strategy. (United States)

    Erbe, Christine; Reichmuth, Colleen; Cunningham, Kane; Lucke, Klaus; Dooling, Robert


    Underwater noise, whether of natural or anthropogenic origin, has the ability to interfere with the way in which marine mammals receive acoustic signals (i.e., for communication, social interaction, foraging, navigation, etc.). This phenomenon, termed auditory masking, has been well studied in humans and terrestrial vertebrates (in particular birds), but less so in marine mammals. Anthropogenic underwater noise seems to be increasing in parts of the world's oceans and concerns about associated bioacoustic effects, including masking, are growing. In this article, we review our understanding of masking in marine mammals, summarise data on marine mammal hearing as they relate to masking (including audiograms, critical ratios, critical bandwidths, and auditory integration times), discuss masking release processes of receivers (including comodulation masking release and spatial release from masking) and anti-masking strategies of signalers (e.g. Lombard effect), and set a research framework for improved assessment of potential masking in marine mammals.

  20. Improved Mask Protected DES using RSA Algorithm

    Directory of Open Access Journals (Sweden)

    Asha Latha S.


    Full Text Available The data encryption standard is a pioneering and farsighted standard which helped to set a new paradigm for encryption standards. But now DES is considered to be insecure for some application. Asymmetric mask protected DES is an advanced encryption method for effectively protecting the advanced DES. There are still probabilities to improve its security. This paper propose a method, which introduce a RSA key generation scheme in mask protected DES instead of plain key, which result in enhancement in the security of present asymmetric mask protected DES. We further propose a Vedic mathematical method of RSA implementation which reduce the complexity of computation in RSA block thereby resulting in reduced delay (four timesthat improves the performance of overall system. The software implementation was performed using Xilinx 13.2 and Model-Sim was used for the simulation environment.

  1. Coherent Diffractive Imaging Using Randomly Coded Masks

    CERN Document Server

    Seaberg, Matthew H; Turner, Joshua J


    Coherent diffractive imaging (CDI) provides new opportunities for high resolution X-ray imaging with simultaneous amplitude and phase contrast. Extensions to CDI broaden the scope of the technique for use in a wide variety of experimental geometries and physical systems. Here, we experimentally demonstrate a new extension to CDI that encodes additional information through the use of a series of randomly coded masks. The information gained from the few additional diffraction measurements removes the need for typical object-domain constraints; the algorithm uses prior information about the masks instead. The experiment is performed using a laser diode at 532.2 nm, enabling rapid prototyping for future X-ray synchrotron and even free electron laser experiments. Diffraction patterns are collected with up to 15 different masks placed between a CCD detector and a single sample. Phase retrieval is performed using a convex relaxation routine known as "PhaseCut" followed by a variation on Fienup's input-output algorit...

  2. Polymer Masks for nanostructuring of graphene

    DEFF Research Database (Denmark)

    Shvets, Violetta

    This PhD project is a part of Center for Nanostructured Graphene (CNG) activities. The aim of the project is to develop a new lithography method for creation of highly ordered nanostructures with as small as possible feature and period sizes. The method should be applicable for graphene...... polymer masks is developed. Mask fabrication is realized by microtoming of 30-60 nm thin sections from pre-aligned polymer monoliths with different morphologies. The resulting polymer masks are then transferred to both silicon and graphene substrates. Hexagonally packed hole patterns with 10 nm hole...... diameter and 20 nm periodicity are successfully transferred to both substrates. The method allowed to realize the first ever transfer of moiré patterns to silicon. Furthermore, in collaboration with CNG, device with nanostructured graphene are fabricated and electrical measurements made on these devices...

  3. Metacontrast masking is processed before grapheme-color synesthesia. (United States)

    Bacon, Michael Patrick; Bridgeman, Bruce; Ramachandran, Vilayanur S


    We investigated the physiological mechanism of grapheme-color synesthesia using metacontrast masking. A metacontrast target is rendered invisible by a mask that is delayed by about 60 ms; the target and mask do not overlap in space or time. Little masking occurs, however, if the target and mask are simultaneous. This effect must be cortical, because it can be obtained dichoptically. To compare the data for synesthetes and controls, we developed a metacontrast design in which nonsynesthete controls showed weaker dichromatic masking (i.e., the target and mask were in different colors) than monochromatic masking. We accomplished this with an equiluminant target, mask, and background for each observer. If synesthetic color affected metacontrast, synesthetes should show monochromatic masking more similar to the weak dichromatic masking among controls, because synesthetes could add their synesthetic color to the monochromatic condition. The target-mask pairs used for each synesthete were graphemes that elicited strong synesthetic colors. We found stronger monochromatic than dichromatic U-shaped metacontrast for both synesthetes and controls, with optimal masking at an asynchrony of 66 ms. The difference in performance between the monochromatic and dichromatic conditions in the synesthetes indicates that synesthesia occurs at a later processing stage than does metacontrast masking.

  4. Synchronous two-wavelength temporal interferometry (United States)

    Zhang, Xiaoqiong; Gao, Zhan; Qin, Jie; Li, Guangyu; Feng, Ziang; Wang, Shengjia


    Interferometry is an optical measuring method with the character of non-destructive, high sensitivity and high accuracy. However, its measurement range is limited by the phase ambiguity. Hence the method with two separate different wavelengths light source is introduced to enlarge the measurement range. As for the two-wavelength interferometry case, phase shifting is the traditional way to acquire the phase map, it needs to repeat the measurement twice, which means the measurement cannot be accomplished in real time. Hence to solve the problem, a temporal sequence interferometry has been used. This method can obtain the desired phase information in real time by using the Fourier transform methods of the interferogram recorded in a sequence while the object is being deformed. But, it is difficult to retrieve the phase information directly due to the multi extreme points in one period of the cosine function. In this paper, an algorithm based on the wavelet ridge analysis is adopted to retrieve the two wavelength phase fluctuation caused by the displacement simultaneously. The preliminary experiment is conducted and the results are compared with theoretical simulations to validate the proposed approach. The laser emits light with two wavelengths 532 nm and 473 nm, two separated interference patterns in time sequence are detected by the CCD camera in the same time. The overlapped interferograms of two colors are analyzed by this algorithm and the corresponding phase information are obtained. The maximum error value between the simulation and theory is 0.03 um and the relative error is 0.33%.

  5. Sub-aperture stitching test of a cylindrical mirror with large aperture (United States)

    Xue, Shuai; Chen, Shanyong; Shi, Feng; Lu, Jinfeng


    Cylindrical mirrors are key optics of high-end equipment of national defense and scientific research such as high energy laser weapons, synchrotron radiation system, etc. However, its surface error test technology develops slowly. As a result, its optical processing quality can not meet the requirements, and the developing of the associated equipment is hindered. Computer Generated-Hologram (CGH) is commonly utilized as null for testing cylindrical optics. However, since the fabrication process of CGH with large aperture is not sophisticated yet, the null test of cylindrical optics with large aperture is limited by the aperture of the CGH. Hence CGH null test combined with sub-aperture stitching method is proposed to break the limit of the aperture of CGH for testing cylindrical optics, and the design of CGH for testing cylindrical surfaces is analyzed. Besides, the misalignment aberration of cylindrical surfaces is different from that of the rotational symmetric surfaces since the special shape of cylindrical surfaces, and the existing stitching algorithm of rotational symmetric surfaces can not meet the requirements of stitching cylindrical surfaces. We therefore analyze the misalignment aberrations of cylindrical surfaces, and study the stitching algorithm for measuring cylindrical optics with large aperture. Finally we test a cylindrical mirror with large aperture to verify the validity of the proposed method.


    Institute of Scientific and Technical Information of China (English)

    Liu Wei; Zhang Chunhua; Liu Jiyuan


    Estimation precision of Displaced Phase Center Algorithm (DPCA) is affected by the number of displaced phase center pairs, the bandwidth of transmitting signal and many other factors. Detailed analysis is made on DPCA's estimation precision. Analysis results show that the directional vector estimation precision of DPCA is low, which will produce accumulating errors when phase centers' track is estimated. Because of this reason, DPCA suffers from accumulating errors seriously. To overcome this problem, a method combining DPCA with Sub Aperture Image Correlation (SAIC) is presented. Large synthetic aperture is divided into sub-apertures. Micro errors in sub-aperture are estimated by DPCA and compensated to raw echo data. Bulk errors between sub-apertures are estimated by SAIC and compensated directly to sub-aperture images. After that, sub-aperture images are directly used to generate ultimate SAS image. The method is applied to the lake-trial dataset of a 20 kHz SAS prototype system. Results show the method can successfully remove the accumulating error and produce a better SAS image.

  7. Three-dimensional glacier surface velocities of the Storstrømmen glacier, Greenland derived from radar interferometry and ice-sounding radar measurements


    Reeh, N; Mohr, J. J.; Madsen, S.N.; Oerter, Hans; Gundestrup, N.


    Non-steady-state vertical velocities of up to 5 m y-1 exceed the vertical surface-parallel-flow components over much of the ablation area of Storstrømmen, a large outlet glacier from the East Greenland ice sheet. Neglecting a contribution to the vertical velocity of this magnitude, results in substantial errors (up to 20%) also on the south north component of horizontal velocities derived by satellite synthetic aperture radar interferometry (InSAR) measurements. In many glacier environments t...

  8. Three-dimensional surface velocities of Storstrømmen glacier, Greenland, derived from radar interferometry and ice-sounding radar measurements

    DEFF Research Database (Denmark)

    Reeh, Niels; Mohr, Johan Jacob; Madsen, Søren Nørvang


    in substantial errors (up to 20%) also on the south-north component of horizontal velocities derived by satellite synthetic aperture radar interferometry (InSAR) measurements. In many glacier environments, the steady-state vertical velocity component required to balance the annual ablation rate is 5-10 m a(-1...... tracks with airborne ice-sounding radar measurement of ice thickness. The results are compared to InSAR velocities previously derived by using the SPF assumption, and to velocities obtained by in situ global positioning system (GPS) measurements. The velocities derived by using the MC principle...

  9. Frequency scanning interferometry for CLIC component fiducialisation

    CERN Document Server

    Kamugasa, Solomon William; Mainaud Durand, Helene; CERN. Geneva. ATS Department


    We present a strategy for the fiducialisation of CLIC’s Main Beam Quadrupole (MBQ) magnets using Frequency Scanning Interferometry (FSI). We have developed complementary device for a commercial FSI system to enable coordinate determination via multilateration. Using spherical high index glass retroreflectors with a wide acceptance angle, we optimise the geometry of measurement stations with respect to fiducials -- thus improving the precision of coordinates. We demonstrate through simulations that the 10 μm uncertainty required in the vertical and lateral axes for the fiducialisation of the MBQ can be attained using FSI multilateration.

  10. Report on ''European Radio Interferometry School 2015'' (United States)

    Laing, R.; Richards, A.


    The sixth European Interferometry School (ERIS2015) was held at ESO for the first time. As usual the school was aimed at graduate students and early-career postdocs, but this year the emphasis was on enhanced wide-bandwidth interferometers covering metre to submillimetre wavebands. More than 100 participants attended ERIS2015. The topics of the school are briefly described here. They covered a wide range, from an introduction to radio interferometric techniques through packages for data reduction and analysis to hands-on workshop sessions and proposal writing.

  11. Atom Interferometry in a Warm Vapor

    CERN Document Server

    Biedermann, G W; Rakholia, A V; Jau, Y -Y; Wheeler, D R; Sterk, J D; Burns, G R


    We demonstrate matterwave interference in a warm vapor of rubidium atoms. Established approaches to light pulse atom interferometry rely on laser cooling to concentrate a large ensemble of atoms into a velocity class resonant with the atom optical light pulse. In our experiment, we show that clear interference signals may be obtained without laser cooling. This effect relies on the Doppler selectivity of the atom interferometer resonance. This interferometer may be configured to measure accelerations, and we demonstrate that multiple interferometers may be operated simultaneously by addressing multiple velocity classes.

  12. Probing Dark Energy with Atom Interferometry

    CERN Document Server

    Burrage, Clare; Hinds, E A


    Theories of dark energy require a screening mechanism to explain why the associated scalar fields do not mediate observable long range fifth forces. The archetype of this is the chameleon field. Here we show that individual atoms are too small to screen the chameleon field inside a large high-vacuum chamber, and therefore can detect the field with high sensitivity. We derive new limits on the chameleon parameters from existing experiments, and show that most of the remaining chameleon parameter space is readily accessible using atom interferometry.

  13. Neutron interferometry constrains dark energy chameleon fields

    Directory of Open Access Journals (Sweden)

    H. Lemmel


    Full Text Available We present phase shift measurements for neutron matter waves in vacuum and in low pressure Helium using a method originally developed for neutron scattering length measurements in neutron interferometry. We search for phase shifts associated with a coupling to scalar fields. We set stringent limits for a scalar chameleon field, a prominent quintessence dark energy candidate. We find that the coupling constant β is less than 1.9×107 for n=1 at 95% confidence level, where n is an input parameter of the self-interaction of the chameleon field φ inversely proportional to φn.

  14. Atomic Interferometry Test of Dark Energy

    CERN Document Server

    Brax, Philippe


    Atomic interferometry can be used to probe dark energy models coupled to matter. We consider the constraints coming from recent experimental results on models generalising the inverse power law chameleons such as $f(R)$ gravity in the large curvature regime, the environmentally dependent dilaton and symmetrons. Using the tomographic description of these models, we find that only symmetrons with masses smaller than the dark energy scale can be efficiently tested. In this regime, the resulting constraints complement the bounds from the E\\"otwash experiment and exclude small values of the symmetron self-coupling.

  15. Stitching algorithm for annular subaperture interferometry

    Institute of Scientific and Technical Information of China (English)

    Xi Hou; Fan Wu; Li Yang; Shibin Wu; Qiang Chen


    @@ Annular subaperture interferometry (ASI) has been developed for low cost and flexible test of rotationally symmetric aspheric surfaces, in which accurately combining the subaperture measurement data corrupted by misalignments and noise into a complete surface figure is the key problem. By introducing the Zernike annular polynomials which are orthogonal over annulus, a method that eliminates the coupling problem in the earlier algorithm based on Zernike circle polynomials is proposed. Vector-matrix notation is used to simplify the description and calculations. The performance of this reduction method is evaluated by numerical simulation. The results prove this method with high precision and good anti-noise capability.

  16. Moire interferometry for vibration analysis of plates (United States)

    Asundi, A.; Cheung, M. T.


    Moire interferometry is used to locate nodal regions and measure vibration amplitudes of sinusoidally vibrating square plates. The high sensitivity afforded by this technique makes possible the study of plate vibrations at high frequencies and low amplitudes. The initial pattern is modulated by the zero-order Bessel function representing the vibratory motion. The fringe (or fringes) with best contrast indicate the nodal regions, while the higher order fringes, describing loci of points vibrating with the same amplitude, have decreasing contrast which is improved by spatial filtering.

  17. Precision polyimide single surface thin film shell apertures and active boundary control (United States)

    Flint, Eric M.; Lindler, Jason E.; Hall, Jonathan L.; Rankine, Charles; Reggelbrugge, Mark


    This paper discusses the current status of self supporting precision membrane optical shell technology (MOST) apertures based on thin (25 to 125 um thick) polyimide and polyester films primary shell. Optically relevant doubly curved reflective apertures are realized by inducing permanent curvature into thin substrates that can then be coated. The initial thin nature provides both very low areal density (20 to 200 grams/m2) and compatibility with compact roll stowage. The induced curvature/depth provides the ability to support the shell around the periphery at discrete locations and considerable structural and dynamic stiffness. The discrete mounts also provide an excellent location with which to improve the surface figure and to reject environmental and host structure induced errors. Material microroughness on the leading substrate/coating combination has been measured to down to 3 nm rms over small (100x100um's) sample sizes with white light interferometry. A variety of reflective coated substrates have also been shown to have sub micron rms surface roughness over up to 100mm diameter test apertures using interferometric measurements. Best materials currently have 20nm rms surface roughness noise floors at these sizes. The ability to fabricate shells over a range of prescriptions (R/0.9 to R/2.2) and a range of sizes (0.1 to 0.75m diameter) has been demonstrated. Global surface figure accuracies of 2 to 4 microns rms have been demonstrated at the 0.2m size, and further improvements are anticipated through ongoing improved fabrication techniques (preliminary results indicate sub-micron rms values). The ability of discrete boundary control to improve the shape and maintain it in the face of disturbances (gravity for example) is demonstrated as is the ability to implement high amplitude (multi-wave) Zernike mode surface figure control. Results extending boundary control to interferometric optical level are also presented.

  18. High quality mask storage in an advanced Logic-Fab (United States)

    Jähnert, Carmen; Fritsche, Silvio


    High efficient mask logistics as well as safe and high quality mask storage are essential requirements within an advanced lithography area of a modern logic waferfab. Fast operational availability of the required masks at the exposure tool with excellent mask condition requires a safe mask handling, safeguarding of high mask quality over the whole mask usage time without any quality degradation and an intelligent mask logistics. One big challenge is the prevention of haze on high advanced phase shift masks used in a high volume production line for some thousands of 248nm or 193nm exposures. In 2008 Infineon Dresden qualified a customer specific developed semi-bare mask storage system from DMSDynamic Micro Systems in combination with a high advanced mask handling and an interconnected complex logistic system. This high-capacity mask storage system DMS M1900.22 for more than 3000 masks with fully automated mask and box handling as well as full-blown XCDA purge has been developed and adapted to the Infineon Lithotoollandscape using Nikon and SMIF reticle cases. Advanced features for ESD safety and mask security, mask tracking via RFID and interactions with the exposure tools were developed and implemented. The stocker is remote controlled by the iCADA-RSM system, ordering of the requested mask directly from the affected exposure tool allows fast access. This paper discusses the advantages and challenges for this approach as well as the practical experience gained during the implementation of the new system which improves the fab performance with respect to mask quality, security and throughput. Especially the realization of an extremely low and stable humidity level in addition with a well controlled air flow at each mask surface, preventing masks from haze degradation and particle contamination, turns out to be a notable technical achievement. The longterm stability of haze critical masks has been improved significantly. Relevant environmental parameters like

  19. Coded aperture coherent scatter imaging for breast cancer detection: a Monte Carlo evaluation (United States)

    Lakshmanan, Manu N.; Morris, Robert E.; Greenberg, Joel A.; Samei, Ehsan; Kapadia, Anuj J.


    It is known that conventional x-ray imaging provides a maximum contrast between cancerous and healthy fibroglandular breast tissues of 3% based on their linear x-ray attenuation coefficients at 17.5 keV, whereas coherent scatter signal provides a maximum contrast of 19% based on their differential coherent scatter cross sections. Therefore in order to exploit this potential contrast, we seek to evaluate the performance of a coded- aperture coherent scatter imaging system for breast cancer detection and investigate its accuracy using Monte Carlo simulations. In the simulations we modeled our experimental system, which consists of a raster-scanned pencil beam of x-rays, a bismuth-tin coded aperture mask comprised of a repeating slit pattern with 2-mm periodicity, and a linear-array of 128 detector pixels with 6.5-keV energy resolution. The breast tissue that was scanned comprised a 3-cm sample taken from a patient-based XCAT breast phantom containing a tomosynthesis- based realistic simulated lesion. The differential coherent scatter cross section was reconstructed at each pixel in the image using an iterative reconstruction algorithm. Each pixel in the reconstructed image was then classified as being either air or the type of breast tissue with which its normalized reconstructed differential coherent scatter cross section had the highest correlation coefficient. Comparison of the final tissue classification results with the ground truth image showed that the coded aperture imaging technique has a cancerous pixel detection sensitivity (correct identification of cancerous pixels), specificity (correctly ruling out healthy pixels as not being cancer) and accuracy of 92.4%, 91.9% and 92.0%, respectively. Our Monte Carlo evaluation of our experimental coded aperture coherent scatter imaging system shows that it is able to exploit the greater contrast available from coherently scattered x-rays to increase the accuracy of detecting cancerous regions within the breast.

  20. Advances in mask fabrication and alignment for masked ion-beam lithography (United States)

    Stumbo, David P.; Damm, George A.; Engler, D. W.; Fong, F. O.; Sen, S.; Wolfe, John C.; Randall, John N.; Mauger, Phillip E.; Shimkunas, Alex R.; Loeschne, Hans


    This paper describes recent developments in three areas ofmasked ion beam lithography (MIBL). These are 1) fabrication oflarge area, low distortion, silicon stencilmasks for demagnifying ion projection lithography, 2) fabrication ofstencil masks with nanometer scale resolution for 1:1 proximity printing, and 3) development of a direct method of alignment using the ion beam induced fluorescence of Si02. These topics are discussed below. Demagnifying ion projection masks: We describe the fabrication of stencil masks in large area, low stress (10 MPa), n-type silicon membranes. The projection masks have a silicon foil area 95 mm in diameter, thicknesses between 1.5-5 and resolution of0.6um. Measured distortion (3a) in the IPL masks ranges between 0.23gm and 0.65,um, with an experimental error of 0.20 1um. Proximity printing masks: A process is described for fabricating stencil masks with 50 nm resolution in low stress, n-type silicon membranes. Membranes less than 0.5 ,ttm thick are shown to be free of the sidewall taper that limits resolution in thicker masks. These thin membranes show a slightly flared profile due to the imperfectly collimated etching ions. Alignment: A direct method of alignment is being developed which uses the ion beam induced fluorescence of Si02 marks. Fluorescence yield is characterized as a function of ion energy and resist coating thickness. The yield for Si02 is in the range between 0.1-1.0 photons/proton, while the yields for Si, Al, and photoresist are negligibly small. Thus, a simple alignment technique can be implemented where registration of a grating in the mask with a corresponding oxide pattern is detected as a fluorescence maximum. A simple model predicts that 50 nm alignment can be accomplished, following a 1 im prealignment, in 2 seconds.

  1. Cosmic Ballet or Devil's Mask? (United States)


    Stars like our Sun are members of galaxies, and most galaxies are themselves members of clusters of galaxies. In these, they move around among each other in a mostly slow and graceful ballet. But every now and then, two or more of the members may get too close for comfort - the movements become hectic, sometimes indeed dramatic, as when galaxies end up colliding. ESO PR Photo 12/04 shows an example of such a cosmic tango. This is the superb triple system NGC 6769-71, located in the southern Pavo constellation (the Peacock) at a distance of 190 million light-years. This composite image was obtained on April 1, 2004, the day of the Fifth Anniversary of ESO's Very Large Telescope (VLT). It was taken in the imaging mode of the VIsible Multi-Object Spectrograph (VIMOS) on Melipal, one of the four 8.2-m Unit Telescopes of the VLT at the Paranal Observatory (Chile). The two upper galaxies, NGC 6769 (upper right) and NGC 6770 (upper left), are of equal brightness and size, while NGC 6771 (below) is about half as bright and slightly smaller. All three galaxies possess a central bulge of similar brightness. They consist of elderly, reddish stars and that of NGC 6771 is remarkable for its "boxy" shape, a rare occurrence among galaxies. Gravitational interaction in a small galaxy group NGC 6769 is a spiral galaxy with very tightly wound spiral arms, while NGC 6770 has two major spiral arms, one of which is rather straight and points towards the outer disc of NGC 6769. NGC 6770 is also peculiar in that it presents two comparatively straight dark lanes and a fainter arc that curves towards the third galaxy, NGC 6771 (below). It is also obvious from this new VLT photo that stars and gas have been stripped off NGC 6769 and NGC 6770, starting to form a common envelope around them, in the shape of a Devil's Mask. There is also a weak hint of a tenuous bridge between NGC 6769 and NGC 6771. All of these features testify to strong gravitational interaction between the three galaxies

  2. Design and performance of coded aperture optical elements for the CESR-TA x-ray beam size monitor (United States)

    Alexander, J. P.; Chatterjee, A.; Conolly, C.; Edwards, E.; Ehrlichman, M. P.; Flanagan, J. W.; Fontes, E.; Heltsley, B. K.; Lyndaker, A.; Peterson, D. P.; Rider, N. T.; Rubin, D. L.; Seeley, R.; Shanks, J.


    We describe the design and performance of optical elements for an x-ray beam size monitor (xBSM), a device measuring e+ and e- beam sizes in the CESR-TA storage ring. The device can measure vertical beam sizes of 10 - 100 μm on a turn-by-turn, bunch-by-bunch basis at e± beam energies of ~ 2 - 5 GeV. x-rays produced by a hard-bend magnet pass through a single- or multiple-slit (coded aperture) optical element onto a detector. The coded aperture slit pattern and thickness of masking material forming that pattern can both be tuned for optimal resolving power. We describe several such optical elements and show how well predictions of simple models track measured performances.

  3. Design and performance of coded aperture optical elements for the CESR-TA x-ray beam size monitor

    CERN Document Server

    Alexander, J P; Conolly, C; Edwards, E; Ehrlichman, M P; Flanagan, J W; Fontes, E; Heltsley, B K; Lyndaker, A; Peterson, D P; Rider, N T; Rubin, D L; Seeley, R; Shanks, J


    We describe the design and performance of optical elements for an x-ray beam size monitor (xBSM), a device measuring $e^+$ and $e^-$ beam sizes in the CESR-TA storage ring. The device can measure vertical beam sizes of $10-100~\\mu$m on a turn-by-turn, bunch-by-bunch basis at $e^\\pm$ beam energies of $\\sim2-5~$GeV. X-rays produced by a hard-bend magnet pass through a single- or multiple-slit (coded aperture) optical element onto a detector. The coded aperture slit pattern and thickness of masking material forming that pattern can both be tuned for optimal resolving power. We describe several such optical elements and show how well predictions of simple models track measured performances.

  4. Synthetic Aperture Beamformation using the GPU

    DEFF Research Database (Denmark)

    Hansen, Jens Munk; Schaa, Dana; Jensen, Jørgen Arendt


    A synthetic aperture ultrasound beamformer is implemented for a GPU using the OpenCL framework. The implementation supports beamformation of either RF signals or complex baseband signals. Transmit and receive apodization can be either parametric or dynamic using a fixed F-number, a reference, and...... workstation with 2 quad-core Xeon-processors....

  5. Very Large Aperture Diffractive Space Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Hyde, Roderick Allen


    A very large (10's of meters) aperture space telescope including two separate spacecraft--an optical primary functioning as a magnifying glass and an optical secondary functioning as an eyepiece. The spacecraft are spaced up to several kilometers apart with the eyepiece directly behind the magnifying glass ''aiming'' at an intended target with their relative orientation determining the optical axis of the telescope and hence the targets being observed. The magnifying glass includes a very large-aperture, very-thin-membrane, diffractive lens, e.g., a Fresnel lens, which intercepts incoming light over its full aperture and focuses it towards the eyepiece. The eyepiece has a much smaller, meter-scale aperture and is designed to move along the focal surface of the magnifying glass, gathering up the incoming light and converting it to high quality images. The positions of the two space craft are controlled both to maintain a good optical focus and to point at desired targets.

  6. Optimization of Spatiotemporal Apertures in Channel Sounding

    DEFF Research Database (Denmark)

    Pedersen, Troels; Pedersen, Claus; Yin, Xuefeng;


    In this paper we investigate the impact of the spatio-temporal aperture of a channel sounding system equipped with antenna arrays at the transmitter and receiver on the accuracy of joint estimation of Doppler frequency and bi-direction. The contribution of this work is three-fold. Firstly, we sta...

  7. Vowel Aperture and Syllable Segmentation in French (United States)

    Goslin, Jeremy; Frauenfelder, Ulrich H.


    The theories of Pulgram (1970) suggest that if the vowel of a French syllable is open then it will induce syllable segmentation responses that result in the syllable being closed, and vice versa. After the empirical verification that our target French-speaking population was capable of distinguishing between mid-vowel aperture, we examined the…

  8. Interdisciplinary science with large aperture detectors

    Directory of Open Access Journals (Sweden)

    Wiencke Lawrence


    Full Text Available Large aperture detector systems to measure high energy cosmic rays also offer unique opportunities in other areas of science. Disciplines include geophysics such as seismic and volcanic activity, and atmospheric science ranging from clouds to lightning to aerosols to optical transients. This paper will discuss potential opportunities based on the ongoing experience of the Pierre Auger Observatory.

  9. Dynamic metamaterial aperture for microwave imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sleasman, Timothy; Imani, Mohammadreza F.; Gollub, Jonah N.; Smith, David R. [Center for Metamaterials and Integrated Plasmonics, Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina, 27708 (United States)


    We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.

  10. Optimization of Synthetic Aperture Image Quality

    DEFF Research Database (Denmark)

    Moshavegh, Ramin; Jensen, Jonas; Villagómez Hoyos, Carlos Armando;


    Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameter...

  11. Radiation safety considerations in proton aperture disposal. (United States)

    Walker, Priscilla K; Edwards, Andrew C; Das, Indra J; Johnstone, Peter A S


    Beam shaping in scattered and uniform scanned proton beam therapy (PBT) is made commonly by brass apertures. Due to proton interactions, these devices become radioactive and could pose safety issues and radiation hazards. Nearly 2,000 patient-specific devices per year are used at Indiana University Cyclotron Operations (IUCO) and IU Health Proton Therapy Center (IUHPTC); these devices require proper guidelines for disposal. IUCO practice has been to store these apertures for at least 4 mo to allow for safe transfer to recycling contractors. The devices require decay in two staged secure locations, including at least 4 mo in a separate building, at which point half are ready for disposal. At 6 mo, 20-30% of apertures require further storage. This process requires significant space and manpower and should be considered in the design process for new clinical facilities. More widespread adoption of pencil beam or spot scanning nozzles may obviate this issue, as apertures then will no longer be necessary.

  12. Diffraction contrast imaging using virtual apertures

    Energy Technology Data Exchange (ETDEWEB)

    Gammer, Christoph, E-mail: [National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory (United States); Department of Materials Science and Engineering, University of California, Berkeley (United States); Physics of Nanostructured Materials, Faculty of Physics, University of Vienna (Austria); Burak Ozdol, V. [National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory (United States); Liebscher, Christian H.; Minor, Andrew M. [National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory (United States); Department of Materials Science and Engineering, University of California, Berkeley (United States)


    Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast. - Highlights: • A dataset containing all structural information of a given position is recorded. • The dataset allows reconstruction of virtual diffraction patterns or images. • Specific virtual apertures are designed to image precipitates in a complex alloy. • Virtual diffraction patterns from arbitrarily small regions can be established. • Using STEM diffraction to record the dataset is more efficient than TEM dark-field.

  13. Adaptation to different noninvasive ventilation masks in critically ill patients

    Directory of Open Access Journals (Sweden)

    Renata Matos da Silva


    Full Text Available OBJECTIVE: To identify which noninvasive ventilation (NIV masks are most commonly used and the problems related to the adaptation to such masks in critically ill patients admitted to a hospital in the city of São Paulo, Brazil. METHODS: An observational study involving patients ≥ 18 years of age admitted to intensive care units and submitted to NIV. The reason for NIV use, type of mask, NIV regimen, adaptation to the mask, and reasons for non-adaptation to the mask were investigated. RESULTS: We evaluated 245 patients, with a median age of 82 years. Acute respiratory failure was the most common reason for NIV use (in 71.3%. Total face masks were the most commonly used (in 74.7%, followed by full face masks and near-total face masks (in 24.5% and 0.8%, respectively. Intermittent NIV was used in 82.4% of the patients. Adequate adaptation to the mask was found in 76% of the patients. Masks had to be replaced by another type of mask in 24% of the patients. Adequate adaptation to total face masks and full face masks was found in 75.5% and 80.0% of the patients, respectively. Non-adaptation occurred in the 2 patients using near-total facial masks. The most common reason for non-adaptation was the shape of the face, in 30.5% of the patients. CONCLUSIONS: In our sample, acute respiratory failure was the most common reason for NIV use, and total face masks were the most commonly used. The most common reason for non-adaptation to the mask was the shape of the face, which was resolved by changing the type of mask employed.

  14. Femtosecond laser direct hard mask writing for selective facile micron-scale inverted-pyramid patterning of silicon (United States)

    Kumar, K.; Lee, K. K. C.; Herman, P. R.; Nogami, J.; Kherani, N. P.


    We report on the fabrication of high-fidelity inverted-pyramids in crystalline silicon (c-Si) at the 1 μm scale through the selective removal of a silicon nitride (SiNx) hard-mask with a 522 nm femtosecond (fs) laser and subsequent alkaline potassium hydroxide (KOH) etching. Through a series of systematic experiments on a range of hard-mask thicknesses, the use of 20 nm thick SiNx film yielded a 0.6 μm diameter laser-ejected aperture in the hard-mask at a single pulse fluence of 0.45 J cm-2, resulting in 1 μm wide inverted-pyramid structure in c-Si after KOH etching. Anisotropic KOH etching of the partially amorphized c-Si underlying the fs-laser patterned hard mask was found to render clean (111) planes of c-Si. An array of inverted-pyramids on c-Si surfaces as large as 4 cm2 was produced with a defect density of less than 1 in 104. This facile, non-contact, and cleanroom-independent technique serves a variety of applications including anti-reflective texturing of thin c-Si for photovoltaics, wafer marking, labeling, and fabrication of microfluidic and optical devices or laboratories on silicon wafers.

  15. Mask cycle time reduction for foundry projects (United States)

    Balasinski, A.


    One of key deliverables of foundry based manufacturing is low cycletime. Building new and enhancing existing products by mask changes involves significant logistical effort, which could be reduced by standardizing data management and communication procedures among design house, mask shop, and foundry (fab) [1]. As an example, a typical process of taping out can take up to two weeks in addition to technical effort, for database handling, mask form completion, management approval, PO signoff and JDV review, translating into loss of revenue. In order to reduce this delay, we are proposing to develop a unified online system which should assist with the following functions: database edits, final verifications, document approvals, mask order entries, and JDV review with engineering signoff as required. This would help a growing number of semiconductor products to be flexibly manufactured at different manufacturing sites. We discuss how the data architecture based on a non-relational database management system (NRDMBS) extracted into a relational one (RDMBS) should provide quality information [2], to reduce cycle time significantly beyond 70% for an example 2 week tapeout schedule.

  16. A new mask exposure and analysis facility

    NARCIS (Netherlands)

    Sligte, E. te; Koster, N.B.; Deutz, A.F.; Staring, W.P.M.


    The introduction of ever higher source powers in EUV systems causes increased risks for contamination and degradation of EUV masks and pellicles. Appropriate testing can help to inventory and mitigate these risks. To this end, we propose EBL2: a laboratory EUV exposure system capable of operating at

  17. The fastest saccadic responses escape visual masking.

    Directory of Open Access Journals (Sweden)

    Sébastien M Crouzet

    Full Text Available Object-substitution masking (OSM occurs when a briefly presented target in a search array is surrounded by small dots that remain visible after the target disappears. The reduction of target visibility occurring after OSM has been suggested to result from a specific interference with reentrant visual processing while the initial feedforward processing is thought to be left intact. We tested a prediction derived from this hypothesis: the fastest responses, being triggered before the beginning of reentrant processing, should escape the OSM interference. In a saccadic choice reaction time task, which gives access to very early stages of visual processing, target visibility was reduced either by OSM, conventional backward masking, or low stimulus contrast. A general reduction of performance was observed in all three conditions. However, the fastest saccades did not show any sign of interference under either OSM or backward masking, as they did under the low-contrast condition. This finding supports the hypothesis that masking interferes mostly with reentrant processing at later stages, while leaving early feedforward processing largely intact.

  18. The laryngeal mask airway at altitude. (United States)

    Wilson, Grant D; Sittig, Steven E; Schears, Gregory J


    The Laryngeal Mask Airway (LMA) is an accepted adjunct for airway management in emergency patients. There are a number of case reports describing its use in transport medicine for infant to adult patients, including during flight. Although studies of the effect altitude has on air-filled tracheal tubes exists, we were unable to find documentation of the effect of altitude on laryngeal mask airways. Our objective was to assess the effect of altitude on the LMA in both fixed wing and rotary wing models. We performed an in vitro study of the effect of altitude on the LMA cuff. Infant and adult airway trainer mannequins with properly sized and inserted LMA-Classic laryngeal mask airways were monitored for cuff pressure changes while flown at altitudes commonly encountered during air medical transport. Both models demonstrated that LMA cuff pressures may exceed manufacturer recommended levels for safe use even at the relatively low altitudes experienced during rotor wing flight. Properly inserted and inflated laryngeal mask airways at ground level may result in overinflated LMA cuffs when flown to altitudes commonly used for rotor and fixed wing medical transport unless monitored and corrected.


    Directory of Open Access Journals (Sweden)

    Srivastava Saurabh


    Full Text Available Taste is an important factor in the development of dosage form. Nevertheless it is that arena of product development that has been overlooked and undermined for its importance. The problem of bitter and obnoxious taste of is a challenge to the pharmacist in the present scenario. Taste is an important parameter governing compliance. Several oral pharmaceuticals and bulking agents have unpleasant, bitter-tasting components. In numerous cases, the bitter taste modality is an undesirable trait of the product or formulations and can considerably affect its acceptability by consumers. Bitter characteristics found in such systems have been eliminated or minimized by various known processes, but no universally applicable technology for bitterness inhibition has ever been recognized. The desire of improved palatability in these products has prompted the development of numerous formulations with improved performance and acceptability Taste masking technologies offer a great scope for invention and patents. Several approaches like adding flavors and sweeteners, use of coating polymers for inhibiting bitterness, microencapsulation, prodrug formation, formation of inclusion and molecular complexes, solid dispersion system, addition of effervescent agents and application of ion exchange resins have been tried by the formulators to mask the unpleasant taste of the bitter drugs. The present review attempts to give a brief account of different technologies of taste masking with respect to dosage form and novel methods of evaluation of taste masking effect.

  20. Testing Tactile Masking between the Forearms. (United States)

    D'Amour, Sarah; Harris, Laurence R


    Masking, in which one stimulus affects the detection of another, is a classic technique that has been used in visual, auditory, and tactile research, usually using stimuli that are close together to reveal local interactions. Masking effects have also been demonstrated in which a tactile stimulus alters the perception of a touch at a distant location. Such effects can provide insight into how components of the body's representations in the brain may be linked. Occasional reports have indicated that touches on one hand or forearm can affect tactile sensitivity at corresponding contralateral locations. To explore the matching of corresponding points across the body, we can measure the spatial tuning and effect of posture on contralateral masking. Careful controls are required to rule out direct effects of the remote stimulus, for example by mechanical transmission, and also attention effects in which thresholds may be altered by the participant's attention being drawn away from the stimulus of interest. The use of this technique is beneficial as a behavioural measure for exploring which parts of the body are functionally connected and whether the two sides of the body interact in a somatotopic representation. This manuscript describes a behavioural protocol that can be used for studying contralateral tactile masking.

  1. Posleslovije k "Zolotoi maske" / Boris Tuch

    Index Scriptorium Estoniae

    Tuch, Boris, 1946-


    Vene draamafestivali "Kuldne mask Eestis" lavastusest : "September.doc", lav. Mihhail Ugarov, I. Võrõpajevi "Hapnik" lav. Viktor Rõzhakov Teatr.doc esituses, Sophoklese "Kuningas Oidipus" lav. Andrei Prikotenko Peterburi Teatri Liteinõi esituses, M. Ugarovi lavastus "OblomOFF"

  2. Masked object registration in the Fourier domain. (United States)

    Padfield, Dirk


    Registration is one of the most common tasks of image analysis and computer vision applications. The requirements of most registration algorithms include large capture range and fast computation so that the algorithms are robust to different scenarios and can be computed in a reasonable amount of time. For these purposes, registration in the Fourier domain using normalized cross-correlation is well suited and has been extensively studied in the literature. Another common requirement is masking, which is necessary for applications where certain regions of the image that would adversely affect the registration result should be ignored. To address these requirements, we have derived a mathematical model that describes an exact form for embedding the masking step fully into the Fourier domain so that all steps of translation registration can be computed efficiently using Fast Fourier Transforms. We provide algorithms and implementation details that demonstrate the correctness of our derivations. We also demonstrate how this masked FFT registration approach can be applied to improve the Fourier-Mellin algorithm that calculates translation, rotation, and scale in the Fourier domain. We demonstrate the computational efficiency, advantages, and correctness of our algorithm on a number of images from real-world applications. Our framework enables fast, global, parameter-free registration of images with masked regions.

  3. Cavity-excited Huygens' metasurface antennas: near-unity aperture efficiency from arbitrarily-large apertures

    CERN Document Server

    Epstein, Ariel; Eleftheriades, George V


    One of the long-standing problems in antenna engineering is the realization of highly-directive beams using low-profile devices. In this paper we provide a solution to this problem by means of Huygens' metasurfaces (HMSs), based on the equivalence principle. This principle states that a given excitation can be transformed to a desirable aperture field by inducing suitable electric and magnetic surface currents. Building on this concept, we propose and demonstrate cavity-excited HMS antennas, where the single-source cavity excitation is designed to optimize aperture illumination, while the HMS facilitates the current distribution that ensures phase purity of aperture fields. The HMS breaks the coupling between the excitation and radiation spectrum typical to standard partially-reflecting surfaces, allowing tailoring of the aperture properties to produce a desirable radiation pattern. As shown, a single semianalytical formalism can be followed to achieve control of a variety of radiation features, such as the d...

  4. Coded Aperture Nuclear Scintigraphy: A Novel Small Animal Imaging Technique

    Directory of Open Access Journals (Sweden)

    Dawid Schellingerhout


    Full Text Available We introduce and demonstrate the utility of coded aperture (CA nuclear scintigraphy for imaging small animals. CA imaging uses multiple pinholes in a carefully designed mask pattern, mounted on a conventional gamma camera. System performance was assessed using point sources and phantoms, while several animal experiments were performed to test the usefulness of the imaging system in vivo, with commonly used radiopharmaceuticals. The sensitivity of the CA system for 99mTc was 4.2 × 103 cps/Bq (9400 cpm/μCi, compared to 4.4 × 104 cps/Bq (990 cpm/μCi for a conventional collimator system. The system resolution was 1.7 mm, as compared to 4–6 mm for the conventional imaging system (using a high-sensitivity low-energy collimator. Animal imaging demonstrated artifact-free imaging with superior resolution and image quality compared to conventional collimator images in several mouse and rat models. We conclude that: (a CA imaging is a useful nuclear imaging technique for small animal imaging. The advantage in signal-to-noise can be traded to achieve higher resolution, decreased dose or reduced imaging time. (b CA imaging works best for images where activity is concentrated in small volumes; a low count outline may be better demonstrated using conventional collimator imaging. Thus, CA imaging should be viewed as a technique to complement rather than replace traditional nuclear imaging methods. (c CA hardware and software can be readily adapted to existing gamma cameras, making their implementation a relatively inexpensive retrofit to most systems.

  5. Green binary and phase shifting mask (United States)

    Shy, S. L.; Hong, Chao-Sin; Wu, Cheng-San; Chen, S. J.; Wu, Hung-Yu; Ting, Yung-Chiang


    SixNy/Ni thin film green mask blanks were developed , and are now going to be used to replace general chromium film used for binary mask as well as to replace molydium silicide embedded material for AttPSM for I-line (365 nm), KrF (248 nm), ArF (193 nm) and Contact/Proximity lithography. A bilayer structure of a 1 nm thick opaque, conductive nickel layer and a SixNy layer is proposed for binary and phase-shifting mask. With the good controlling of plasma CVD of SixNy under silane (50 sccm), ammonia (5 sccm) and nitrogen (100 sccm), the pressure is 250 mTorr. and RF frequency 13.56 MHz and power 50 W. SixNy has enough deposition latitude to meet the requirements as an embedded layer for required phase shift 180 degree, and the T% in 193, 248 and 365 nm can be adjusted between 2% to 20% for binary and phase shifting mask usage. Ni can be deposited by E-gun, its sheet resistance Rs is less than 1.435 kΩ/square. Jeol e-beam system and I-line stepper are used to evaluate these thin film green mask blanks, feature size less than 200 nm half pitch pattern and 0.558 μm pitch contact hole can be printed. Transmission spectrums of various thickness of SixNy film are inspected by using UV spectrometer and FTIR. Optical constants of the SixNy film are measured by n & k meter and surface roughness is inspected by using Atomic Force Microscope (AFM).

  6. Lithographic performance evaluation of a contaminated EUV mask after cleaning

    Energy Technology Data Exchange (ETDEWEB)

    George, Simi; Naulleau, Patrick; Okoroanyanwu, Uzodinma; Dittmar, Kornelia; Holfeld, Christian; Wuest, Andrea


    The effect of surface contamination and subsequent mask surface cleaning on the lithographic performance of a EUV mask is investigated. SEMATECH's Berkeley micro-field exposure tool (MET) printed 40 nm and 50 nm line and space (L/S) patterns are evaluated to compare the performance of a contaminated and cleaned mask to an uncontaminated mask. Since the two EUV masks have distinct absorber architectures, optical imaging models and aerial image calculations were completed to determine any expected differences in performance. Measured and calculated Bossung curves, process windows, and exposure latitudes for the two sets of L/S patterns are compared to determine how the contamination and cleaning impacts the lithographic performance of EUV masks. The observed differences in mask performance are shown to be insignificant, indicating that the cleaning process did not appreciably affect mask performance.

  7. Coded-aperture imaging using photo-induced reconfigurable aperture arrays for mapping terahertz beams

    CERN Document Server

    Kannegulla, Akash; Rahman, Syed; Fay, Patrick; Xing, Huili Grace; Cheng, Li-Jing; Liu, Lei


    We report terahertz coded-aperture imaging using photo-induced reconfigurable aperture arrays on a silicon wafer. The coded aperture was implemented using programmable illumination from a commercially available digital light processing projector. At 590 GHz, each of the array element apertures can be optically turned on and off with a modulation depth of 20 dB and a modulation rate of ~1.3 KHz. Prototype demonstrations of 4 by 4 coded-aperture imaging using Hadamard coding have been performed and this technique has been successfully applied to mapping THz beams by using a 6 by 6 aperture array at 590 GHz. The imaging results agree closely with theoretical calculations based on Gaussian beam transformation, demonstrating that this technique is promising for realizing real-time and low-cost terahertz cameras for many applications. The reported approach provides a simple but powerful means to visualize THz beams, which is highly desired in quasi-optical system alignment, quantum-cascade laser design and characte...

  8. Effects of the combination of mask preconditioning with midazolam pretreatment on anxiety and mask acceptance during pediatric inhalational induction and postoperative mask fear in children

    Institute of Scientific and Technical Information of China (English)

    LAN Yun-ping; HUANG Zhen-hua; G.Allen Finley; ZUO Yun-xia


    Background Anxiety and fear frequently causes an aversion to applying a face mask and increases difficulty during pediatric induction.There is at present little study of this problem.Therefore,the aim of this study was to investigate the effect of the combination of mask preconditioning and midazolam pretrealment on mask acceptance during pediatric induction and on postoperative mask fear.Methods One hundred and sixty children were randomly assigned into four groups:the mask preconditioning group (MaG),the midazolam pretreatment group (MiG),the mask/midazolam combination group (Ma/MiG),and the saline group (SaG).The Modified Yale Preoperative Anxiety Scale (m-YPAS) was employed to assess the anxiety in the operation room (OR).A Mask Acceptance Score (MAS) was measured during inhalational induction and the incidence of mask fear (MAS ≤2) was evaluated postoperatively.Results The MaG and Ma/MiG groups had the highest mask acceptance scores but there were no differences between these two groups (P <0.05).The average anxiety level of children entering the OR was much lower in the MaG and Ma/MiG groups than in the SaG group (P <0.05).During induction,the anxiety level increased in the SaG and MaG groups but decreased in the MiG and Ma/MiG groups (P <0.05).At the postoperative third day,the incidence of mask fears was as high as 23% in the SaG group,15% in the MiG group,but only 2.5% in the MaG and Ma/MiG groups.Conclusions The single use of mask preconditioning has a better influence than midazolam for increasing mask acceptance during inhalational induction and reducing postoperative mask fear,reducing the anxiety level during induction,improving induction compliance and shortening the total mask time.A mask preconditioning and midazolam combination did not increase mask acceptance during inhalational induction,reduce mask fears postoperatively,improve induction compliance,nor shorten the total mask time.But it can better reduce the anxiety level during

  9. High Gain, Very Low Areal Density, Scalable RF Apertures Enabled by Membrane Aperture Shell Technology (MAST) Project (United States)

    National Aeronautics and Space Administration — We propose that the Membrane Aperture Shell Technology (MAST) approach be expanded with a specific focus on space exploration orbiting comm network RF aperture...

  10. How color, regularity, and good Gestalt determine backward masking. (United States)

    Sayim, Bilge; Manassi, Mauro; Herzog, Michael


    The strength of visual backward masking depends on the stimulus onset asynchrony (SOA) between target and mask. Recently, it was shown that the conjoint spatial layout of target and mask is as crucial as SOA. Particularly, masking strength depends on whether target and mask group with each other. The same is true in crowding where the global spatial layout of the flankers and target-flanker grouping determine crowding strength. Here, we presented a vernier target followed by different flanker configurations at varying SOAs. Similar to crowding, masking of a red vernier target was strongly reduced for arrays of 10 green compared with 10 red flanking lines. Unlike crowding, single green lines flanking the red vernier showed strong masking. Irregularly arranged flanking lines yielded stronger masking than did regularly arranged lines, again similar to crowding. While cuboid flankers reduced crowding compared with single lines, this was not the case in masking. We propose that, first, masking is reduced when the flankers are part of a larger spatial structure. Second, spatial factors counteract color differences between the target and the flankers. Third, complex Gestalts, such as cuboids, seem to need longer processing times to show ungrouping effects as observed in crowding. Strong parallels between masking and crowding suggest similar underlying mechanism; however, temporal factors in masking additionally modulate performance, acting as an additional grouping cue.

  11. Model-based mask data preparation (MB-MDP) for ArF and EUV mask process correction (United States)

    Hagiwara, Kazuyuki; Bork, Ingo; Fujimura, Aki


    Using Model-Based Mask Data Preparation (MB-MDP) complex masks with complex sub-resolution assist features (SRAFs) can be written in practical write times with today's leading-edge production VSB machines by allowing overlapping VSB shots. This simulation-based approach reduces shot count by taking advantage of the added flexibility in being able to overlap shots. The freedom to overlap shots, it turns out, also increases mask fidelity, CDU on the mask, and CDU on the wafer by writing sub-100nm mask features more accurately, and with better dose margin. This paper describes how overlapping shots enhance mask and wafer quality for various sub-100nm features on ArF masks. In addition, this paper describes how EUV mask accuracy can be enhanced uniquely by allowing overlapping shots.

  12. Generalized interferometry - I: theory for interstation correlations (United States)

    Fichtner, Andreas; Stehly, Laurent; Ermert, Laura; Boehm, Christian


    We develop a general theory for interferometry by correlation that (i) properly accounts for heterogeneously distributed sources of continuous or transient nature, (ii) fully incorporates any type of linear and nonlinear processing, such as one-bit normalization, spectral whitening and phase-weighted stacking, (iii) operates for any type of medium, including 3-D elastic, heterogeneous and attenuating media, (iv) enables the exploitation of complete correlation waveforms, including seemingly unphysical arrivals, and (v) unifies the earthquake-based two-station method and ambient noise correlations. Our central theme is not to equate interferometry with Green function retrieval, and to extract information directly from processed interstation correlations, regardless of their relation to the Green function. We demonstrate that processing transforms the actual wavefield sources and actual wave propagation physics into effective sources and effective wave propagation. This transformation is uniquely determined by the processing applied to the observed data, and can be easily computed. The effective forward model, that links effective sources and propagation to synthetic interstation correlations, may not be perfect. A forward modelling error, induced by processing, describes the extent to which processed correlations can actually be interpreted as proper correlations, that is, as resulting from some effective source and some effective wave propagation. The magnitude of the forward modelling error is controlled by the processing scheme and the temporal variability of the sources. Applying adjoint techniques to the effective forward model, we derive finite-frequency Fréchet kernels for the sources of the wavefield and Earth structure, that should be inverted jointly. The structure kernels depend on the sources of the wavefield and the processing scheme applied to the raw data. Therefore, both must be taken into account correctly in order to make accurate inferences on

  13. Demonstration of high contrast with an obscured aperture with the WFIRST-AFTA shaped pupil coronagraph

    CERN Document Server

    Cady, Eric; An, Xin; Balasubramanian, Kunjithapatham; Diaz, Rosemary; Kasdin, N Jeremy; Kern, Brian; Kuhnert, Andreas; Nemati, Bijan; Poberezhskiy, Ilya; Riggs, A J Eldorado; Zimmer, Robert; Zimmerman, Neil


    The coronagraph instrument on the WFIRST-AFTA mission study has two coronagraphic architectures, shaped pupil and hybrid Lyot, which may be interchanged for use in different observing scenarios. Each architecture relies on newly-developed mask components to function in the presence of the AFTA aperture, and so both must be matured to a high technology readiness level (TRL) in advance of the mission. A series of milestones were set to track the development of the technologies required for the instrument; in this paper, we report on completion of WFIRST-AFTA Coronagraph Milestone 2---a narrowband $10^{-8}$ contrast test with static aberrations for the shaped pupil---and the plans for the upcoming broadband Coronagraph Milestone 5.

  14. Security enhancement of the phase-shifting interferometry-based cryptosystem by independent random phase modulation in each exposure (United States)

    Liao, Meihua; He, Wenqi; Lu, Dajiang; Wu, Jiachen; Peng, Xiang


    The traditional phase-shifting interferometry (PSI)-based cryptosystem is one of the most classical optical cryptosystems. It employs the Mach-Zahnder interferometer to record the intensity distributions to partly overcome the inconvenience while storing the complex-valued ciphertext in some other optical cryptosystems (e.g., double random phase encoding technique). However, it has been proven to be vulnerable to chosen-plaintext attack and known-plaintext attack. In this manuscript, we propose an alternative method to enhance the security strength of the traditional PSI-based cryptosystem. By substituting the fixed random phase mask (RPM) and the phase retarder in the reference arm with four independent and different RPMs (served as secret keys) in four exposures, we can correspondingly capture four intensity-only patterns (regarded as ciphertexts). Theoretical analysis, especially with respect to security characteristics, as well as the numerical simulations are presented to verify the feasibility and reliability of the proposed cryptosystem.

  15. Flame Reconstruction Using Synthetic Aperture Imaging

    CERN Document Server

    Murray, Preston; Tree, Dale; Truscott, Tadd


    Flames can be formed by burning methane (CH4). When oxygen is scarce, carbon particles nucleate into solid particles called soot. These particles emit photons, making the flame yellow. Later, methane is pre-mixed with air forming a blue flame; burning more efficiently, providing less soot and light. Imaging flames and knowing their temperature are vital to maximizing efficiency and validating numerical models. Most temperature probes disrupt the flame and create differences leading to an inaccurate measurement of the flame temperature. We seek to image the flame in three dimensions using synthetic aperture imaging. This technique has already successfully measured velocity fields of a vortex ring [1]. Synthetic aperture imaging is a technique that views one scene from multiple cameras set at different angles, allowing some cameras to view objects that are obscured by others. As the resulting images are overlapped different depths of the scene come into and out of focus, known as focal planes, similar to tomogr...

  16. Design of large aperture focal plane shutter (United States)

    Hu, Jia-wen; Ma, Wen-li; Huang, Jin-long


    To satisfy the requirement of large telescope, a large aperture focal plane shutter with aperture size of φ200mm was researched and designed to realize, which could be started and stopped in a relative short time with precise position, and also the blades could open and close at the same time at any orientation. Timing-belts and stepper motors were adopted as the drive mechanism. Velocity and position of the stepper motors were controlled by the PWM pulse generated by DSP. Exponential curve is applied to control the velocity of the stepper motors to make the shutter start and stop in a short time. The closing/open time of shutter is 0.2s, which meets the performance requirements of large telescope properly.

  17. IR aperture measurement at β*=40 cm

    CERN Document Server

    Bruce, Roderik; Hermes, Pascal Dominik; Kwee-Hinzmann, Regina; Mereghetti, Alessio; Mirarchi, Daniele; Redaelli, Stefano; Salvachua Ferrando, Belen Maria; Skowronski, Piotr Krzysztof; Valentino, Gianluca; Valloni, Alessandra; CERN. Geneva. ATS Department


    This note summarizes MD 307, performed on August 27 2015, during which we measured with beam the global apertures at 6.5 TeV with IR1 and IR5 squeezed to β* =40 cm and a half crossing angle of 205 rad. The measurement technique involved opening collimators in steps, while inducing beam losses at each step, until the main loss location moved from the collimators to the global bottleneck in one of the triplets. Measurements were performed in both beams and planes, and each measurement gave the minimum triplet aperture over IR1 and IR5. The results are in very good agreement with theoretical predictions. At the end of the MD, an asynchronous beam dump test was performed with all collimators moved in to so-called 2-σ retraction settings. This MD is one in a series meant to address various open points for the reach in β* in Run II.

  18. Parametric Beamformer for Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Tomov, Borislav Gueorguiev; Jensen, Jørgen Arendt


    . The beamformer consists of a number of identical beamforming blocks, each processing data from several channels and producing part of the image. A number of these blocks can be accommodated in a modern field-programmable gate array device (FPGA), and a whole synthetic aperture system can be implemented using......In this paper a parametric beamformer, which can handle all imaging modalities including synthetic aperture imaging, is presented. The image lines and apodization coefficients are specified parametrically, and the lines can have arbitrary orientation and starting point in 3D coordinates...... several FPGAs. For the current implementation, the input data is sampled at 4 times the center frequency of the excitation pulse and is match-filtered in the frequency domain. In-phase and quadrature data are beamformed with a sub-sample precision of the focusing delays of 1/16th of the sampling period...

  19. Externally Dispersed Interferometry for Precision Radial Velocimetry

    CERN Document Server

    Erskine, D J; Edelstein, J; Lloyd, J; Herter, T; Feuerstein, W M; Muirhead, P; Wishnow, E


    Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic spectral comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. The moire pattern shifts in phase in response to a Doppler shift. Moire patterns are broader than the underlying spectral features and more easily survive spectrograph blurring and common distortions. Thus, the EDI technique allows lower resolution spectrographs having relaxed optical tolerances (and therefore higher throughput) to return high precision velocity measurements, which otherwise would be imprecise for the spectrograph alone.

  20. Pulsed-Source Interferometry in Acoustic Imaging (United States)

    Shcheglov, Kirill; Gutierrez, Roman; Tang, Tony K.


    A combination of pulsed-source interferometry and acoustic diffraction has been proposed for use in imaging subsurface microscopic defects and other features in such diverse objects as integrated-circuit chips, specimens of materials, and mechanical parts. A specimen to be inspected by this technique would be mounted with its bottom side in contact with an acoustic transducer driven by a continuous-wave acoustic signal at a suitable frequency, which could be as low as a megahertz or as high as a few hundred gigahertz. The top side of the specimen would be coupled to an object that would have a flat (when not vibrating) top surface and that would serve as the acoustical analog of an optical medium (in effect, an acoustical "optic").

  1. Phase difference enhancement with classical intensity interferometry (United States)

    Shirai, Tomohiro


    It is demonstrated theoretically and experimentally that, as a novel function of classical intensity interferometry, a phase difference distribution recorded in the form of an interferogram can be enhanced by a factor of 2 on the basis of the classical intensity correlation. Such phase difference enhancement which is also referred to as phase difference amplification is, in general, known to be practically important since it increases sensitivity and accuracy in interferometric measurements. The method proposed in this study prevails over the existing methods in the sense that it can be readily implemented without difficulty in comparison with all other methods so far proposed, although the phase difference enhancement is limited to a factor of 2 in our method and thus so is the improvement of sensitivity and accuracy.

  2. Intensity interferometry: Optical imaging with kilometer baselines

    CERN Document Server

    Dravins, Dainis


    Optical imaging with microarcsecond resolution will reveal details across and outside stellar surfaces but requires kilometer-scale interferometers, challenging to realize either on the ground or in space. Intensity interferometry, electronically connecting independent telescopes, has a noise budget that relates to the electronic time resolution, circumventing issues of atmospheric turbulence. Extents up to a few km are becoming realistic with arrays of optical air Cherenkov telescopes (primarily erected for gamma-ray studies), enabling an optical equivalent of radio interferometer arrays. Pioneered by Hanbury Brown and Twiss, digital versions of the technique have now been demonstrated, reconstructing diffraction-limited images from laboratory measurements over hundreds of optical baselines. This review outlines the method from its beginnings, describes current experiments, and sketches prospects for future observations.

  3. Endoscopic low coherence interferometry in upper airways (United States)

    Delacrétaz, Yves; Boss, Daniel; Lang, Florian; Depeursinge, Christian


    We introduce Endoscopic Low Coherence Interferometry to obtain topology of upper airways through commonly used rigid endoscopes. Quantitative dimensioning of upper airways pathologies is crucial to provide maximum health recovery chances, for example in order to choose the correct stent to treat endoluminal obstructing pathologies. Our device is fully compatible with procedures used in day-to-day examinations and can potentially be brought to bedside. Besides this, the approach described here can be almost straightforwardly adapted to other endoscopy-related field of interest, such as gastroscopy and arthroscopy. The principle of the method is first exposed, then filtering procedure used to extract the depth information is described. Finally, demonstration of the method ability to operate on biological samples is assessed through measurements on ex-vivo pork bronchi.

  4. Chameleon Dark Energy and Atom Interferometry

    CERN Document Server

    Elder, Benjamin; Haslinger, Philipp; Jaffe, Matt; Müller, Holger; Hamilton, Paul


    Atom interferometry experiments are searching for evidence of chameleon scalar fields with ever-increasing precision. As experiments become more precise, so too must theoretical predictions. Previous work has made numerous approximations to simplify the calculation, which in general requires solving a 3-dimensional nonlinear partial differential equation (PDE). In this paper, we introduce a new technique for calculating the chameleonic force, using a numerical relaxation scheme on a uniform grid. This technique is more general than previous work, which assumed spherical symmetry to reduce the PDE to a 1-dimensional ordinary differential equation (ODE). We examine the effects of approximations made in previous efforts on this subject, and calculate the chameleonic force in a set-up that closely mimics the recent experiment of Hamilton et al. Specifically, we simulate the vacuum chamber as a cylinder with dimensions matching those of the experiment, taking into account the backreaction of the source mass, its o...

  5. Frequency Scanned Interferometry for ILC Tracker Alignment

    CERN Document Server

    Yang, Hai-Jun; Riles, Keith


    In this paper, we report high-precision absolute distance and vibration measurements performed with frequency scanned interferometry. Absolute distance was determined by counting the interference fringes produced while scanning the laser frequency. High-finesse Fabry-Perot interferometers were used to determine frequency changes during scanning. A dual-laser scanning technique was used to cancel drift errors to improve the absolute distance measurement precision. A new dual-channel FSI demonstration system is also presented which is an interim stage toward practical application of multi-channel distance measurement. Under realistic conditions, a precision of 0.3 microns was achieved for an absolute distance of 0.57 meters. A possible optical alignment system for a silicon tracker is also presented.

  6. Compressed sensing imaging techniques for radio interferometry

    CERN Document Server

    Wiaux, Y; Puy, G; Scaife, A M M; Vandergheynst, P


    Radio interferometry probes astrophysical signals through incomplete and noisy Fourier measurements. The theory of compressed sensing demonstrates that such measurements may actually suffice for accurate reconstruction of sparse or compressible signals. We propose new generic imaging techniques based on convex optimization for global minimization problems defined in this context. The versatility of the framework notably allows introduction of specific prior information on the signals, which offers the possibility of significant improvements of reconstruction relative to the standard local matching pursuit algorithm CLEAN used in radio astronomy. We illustrate the potential of the approach by studying reconstruction performances on simulations of two different kinds of signals observed with very generic interferometric configurations. The first kind is an intensity field of compact astrophysical objects. The second kind is the imprint of cosmic strings in the temperature field of the cosmic microwave backgroun...

  7. Shell deformation studies using holographic interferometry (United States)

    Parmerter, R. R.


    The buckling of shallow spherical shells under pressure has been the subject of many theoretical and experimental papers. Experimental data above the theoretical buckling load of Huang have given rise to speculation that shallow shell theory may not adequately predict the stability of nonsymmetric modes in higher-rise shells which are normally classified as shallow by the Reissner criterion. This article considers holographic interferometry as a noncontact, high-resolution method of measuring prebuckling deformations. Prebuckling deformations of a lambda = 9, h/b = 0.038 shell are Fourier-analyzed. Buckling is found to occur in an N = 5 mode as predicted by Huang's theory. The N = 4 mode was unusually stable, suggesting that even at this low value of h/b, stabilizing effects may be at work.

  8. Self-calibrating common-path interferometry. (United States)

    Porras-Aguilar, Rosario; Falaggis, Konstantinos; Ramirez-San-Juan, Julio C; Ramos-Garcia, Ruben


    A quantitative phase measuring technique is presented that estimates the object phase from a series of phase shifted interferograms that are obtained in a common-path configuration with unknown phase shifts. The derived random phase shifting algorithm for common-path interferometers is based on the Generalized Phase Contrast theory [pl. Opt.40(2), 268 (2001)10.1063/1.1404846], which accounts for the particular image formation and includes effects that are not present in two-beam interferometry. It is shown experimentally that this technique can be used within common-path configurations employing nonlinear liquid crystal materials as self-induced phase filters for quantitative phase imaging without the need of phase shift calibrations. The advantages of such liquid crystal elements compared to spatial light modulator based solutions are given by the cost-effectiveness, self-alignment, and the generation of diminutive dimensions of the phase filter size, giving unique performance advantages.

  9. Interferometry with Photon-Subtracted Thermal Light

    CERN Document Server

    Rafsanjani, Seyed Mohammad Hashemi; Magana-Loaiza, Omar S; Gard, Bryan T; Birrittella, Richard; Koltenbah, B E; Parazzoli, C G; Capron, Barbara A; Gerry, Christopher C; Dowling, Jonathan P; Boyd, Robert W


    We propose and implement a quantum procedure for enhancing the sensitivity with which one can determine the phase shift experienced by a weak light beam possessing thermal statistics in passing through an interferometer. Our procedure entails subtracting exactly one (which can be generalized to m) photons from the light field exiting an interferometer containing a phase-shifting element in one of its arms. As a consequence of the process of photon subtraction, and somewhat surprisingly, the mean photon number and signal-to-noise ratio of the resulting light field are thereby increased, leading to enhanced interferometry. This method can be used to increase measurement sensitivity in a variety of practical applications, including that of forming the image of an object illuminated only by weak thermal light.

  10. Radio sources - Very, Very Long Baseline Interferometry (United States)

    Roberts, D. H.


    With resolution of a thousandth of an arcsecond, the radio technique of Very Long Baseline Interferometry (VLBI) provides astronomers with their highest-resolution view of the universe. Data taken with widely-separated antennas are combined, with the help of atomic clocks, to form a Michelson interferometer whose size may be as great as the earth's diameter. Extraordinary phenomena, from the birth of stars as signaled by the brilliant flashes of powerful interstellar masers to the 'faster-than-light' expansion of the cores of distant quasars, are being explored with this technique. However, earth-bound VLBI suffers from several restrictions due to the location of the component antennas at fixed places on the earth's surface. The use of one or more antennas in space in concert with ground-based equipment will greatly expand the technical and scientific capabilities of VLBI, leading to a more complete and even higher resolution view of cosmic phenomena.

  11. Real-time color holographic interferometry (United States)

    Desse, Jean-Michel; Albe, Felix; Tribillon, Jean-Louis


    A new optical technique based on real-time color holographic interferometry has been developed for analyzing unsteady aerodynamic wakes in fluid mechanics or for measuring displacements and deformations in solid mechanics. The technique's feasibility is demonstrated here. It uses three coherent wavelengths produced simultaneously by a cw laser (mixed argon and krypton). Holograms are recorded on single-layer panchromatic silver halide (Slavich PFG 03C) plates. Results show the optical setup can be adjusted to obtain a uniform background color. The interference fringe pattern visualized is large and colored and exhibits a single central white fringe, which makes the zero order of the interferogram easy to identify. An application in a subsonic wind tunnel is presented, in which the unsteady wake past a cylinder is recorded at high rate.

  12. Ultrafast electrooptic dual-comb interferometry

    CERN Document Server

    Duran, Vicente; Torres-Company, Victor


    The femtosecond laser frequency comb has enabled the 21st century revolution in optical synthesis and metrology. A particularly compelling technique that relies on the broadband coherence of two laser frequency combs is dual-comb interferometry. This method is rapidly advancing the field of optical spectroscopy and empowering new applications, from nonlinear microscopy to laser ranging. Up to now, most dual-comb interferometers were based on modelocked lasers, whose repetition rates have restricted the measurement speed to ~ kHz. Here we demonstrate a novel dual-comb interferometer that is based on electrooptic frequency comb technology and measures consecutive complex spectra at a record-high refresh rate of 25 MHz. These results pave the way for novel scientific and metrology applications of frequency comb generators beyond the realm of molecular spectroscopy, where the measurement of ultrabroadband waveforms is of paramount relevance.

  13. Large-aperture hybrid photo-detector

    Energy Technology Data Exchange (ETDEWEB)

    Kawai, Y. [Institute for Particle and Nuclear Studies, The Graduate University for Advanced Studies, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Electron Tube Division, Hamamatsu Photonics K.K., 314-5 Shimokanzo, Iwata City 438-0193, Shizuoka (Japan)], E-mail:; Nakayama, H.; Kusaka, A.; Kakuno, H.; Abe, T.; Iwasaki, M.; Aihara, H. [Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Tanaka, M. [Institute for Particle and Nuclear Studies, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Shiozawa, M. [Institute for Cosmic Ray Research, University of Tokyo, Higashi-Mozumi, Kamioka-cho, Hida City, Gifu 506-1205 (Japan); Kyushima, H.; Suyama, M. [Electron Tube Division, Hamamatsu Photonics K.K., 314-5 Shimokanzo, Iwata City 438-0193, Shizuoka (Japan)


    We have developed the first complete large-aperture (13-inch diameter) hybrid photo-detector (HPD). The withstanding voltage problem has been overcome and we were able to attain an HPD operating voltage of +20 kV. Adoption of our newly developed backside illumination avalanche diode (AD) was also critical in successfully countering the additional problem of an increase in AD leakage after the activation process. We observed single photon signal timing jitter of under 450 ps in FWHM, electron transit time of {approx}12 ns, and clear pulse height separation up to several photoelectron peaks, all greatly superior to the performance of any conventional large-aperture photomultiplier tubes (PMTs). In addition, our HPD has a much simpler structure than conventional large-aperture PMTs, which simplifies mass production and lowers manufacturing cost. We believe that these attributes position our HPD as the most suitable photo-detector for the next generation mega-ton class water-Cherenkov detector, which is expected to be more than 20x larger than the Super-Kamiokande (SK) detector.

  14. Coded-aperture imaging in nuclear medicine (United States)

    Smith, Warren E.; Barrett, Harrison H.; Aarsvold, John N.


    Coded-aperture imaging is a technique for imaging sources that emit high-energy radiation. This type of imaging involves shadow casting and not reflection or refraction. High-energy sources exist in x ray and gamma-ray astronomy, nuclear reactor fuel-rod imaging, and nuclear medicine. Of these three areas nuclear medicine is perhaps the most challenging because of the limited amount of radiation available and because a three-dimensional source distribution is to be determined. In nuclear medicine a radioactive pharmaceutical is administered to a patient. The pharmaceutical is designed to be taken up by a particular organ of interest, and its distribution provides clinical information about the function of the organ, or the presence of lesions within the organ. This distribution is determined from spatial measurements of the radiation emitted by the radiopharmaceutical. The principles of imaging radiopharmaceutical distributions with coded apertures are reviewed. Included is a discussion of linear shift-variant projection operators and the associated inverse problem. A system developed at the University of Arizona in Tucson consisting of small modular gamma-ray cameras fitted with coded apertures is described.

  15. Interferometry using undulator sources (invited, abstract) (United States)

    Beguiristain, R.; Goldberg, K. A.; Tejnil, E.; Bokor, J.; Medecki, H.; Attwood, D. T.; Jackson, K.


    Optical systems for extreme ultraviolet (EUV) lithography need to use optical components with subnanometer surface figure error tolerances to achieve diffraction-limited performance [M.D. Himel, in Soft X-Ray Projection Lithography, A.M. Hawryluk and R.H. Stulen, eds. (OSA, Washington, D.C., 1993), 18, 1089, and D. Attwood et al., Appl. Opt. 32, 7022 (1993)]. Also, multilayer-coated optics require at-wavelength wavefront measurement to characterize phase effects that cannot be measured by conventional optical interferometry. Furthermore, EUV optical systems will additionally require final testing and alignment at the operational wavelength for adjustment and reduction of the cumulative optical surface errors. Therefore, at-wavelength interferometric measurement of EUV optics will be the necessary metrology tool for the successful development of optics for EUV lithography. An EUV point diffraction interferometer (PDI) has been developed at the Center for X-Ray Optics (CXRO) and has been already in operation for a year [K. Goldberg et al., in Extreme Ultra Lithography, D.T. Attwood and F. Zernike, eds. (OSA, Washington, D.C., 1994), K. Goldberg et al., Proc. SPIE 2437, to be published, and K. Goldberg et al., J. Vac. Sci. Technol. B 13, 2923 (1995)] using an undulator radiation source and coherent optics beamline at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. An overview of the PDI interferometer and some EUV wavefront measurements obtained with this instrument will be presented. In addition, future developments planned for EUV interferometry at CXRO towards the measurement of actual EUV lithography optics will be shown.

  16. Experiments on diffusion in liquids using holographic interferometry (United States)

    Fenichel, Henry; Frankena, Hans; Groen, Fokke


    An experiment is described which uses the technique of holographic interferometry to study diffusion in liquids. The diffusion process can be recorded on double exposed holograms or it can be observed and recorded in real time using video techniques.

  17. Digital speckle pattern shearing interferometry: Limitations and prospects

    DEFF Research Database (Denmark)

    Owner-Petersen, Mette


    requires optical processing of double exposed interferograms. Hence the technique is not in real time. This paper explores the possibilities and limitations for real time shearing fringe observation using the electronic speckle pattern interferometry technique. Prospects for quantitative determination...

  18. Range Surveillance Using Radio Interferometry and TDOA Techniques Project (United States)

    National Aeronautics and Space Administration — The proposed innovation will utilize a small network of remote sensors (Figure 2.1) to perform Radio Interferometry (RI) and Time Difference of Arrival (TDOA)...

  19. Range Surveillance Using Radio Interferometry and TDOA Techniques Project (United States)

    National Aeronautics and Space Administration — The proposed innovation will utilize a small network of remote sensors to perform Radio Interferometry (RI) and Time Difference of Arrival (TDOA) techniques to...

  20. ILT Approach for Compensating 3-D Mask Effects

    Institute of Scientific and Technical Information of China (English)

    XIONG Wei; ZHANG Jinyu; MinChun; WANG Yan; YU Zhiping


    As mask features scale to smaller dimensions,the so-called "3-D mask effects" which have mostly been neglected before,become important.This paper properly models the 3-D thick mask effects,and then analyses the object-based inverse lithography technique using a simulated annealing algorithm to determine the mask shapes that produce the desired on-wafer results.Evaluations against rigorous simulations show that the synthesized masks provide good image fidelity up to 0.94,and this approach gives improved accuracy and faster results than existing methods.

  1. Masking mediated print defect visibility predictor (United States)

    Jing, Xiaochen; Nachlieli, Hila; Shaked, Doron; Shiffman, Smadar; Allebach, Jan P.


    Banding is a well-known artifact produced by printing systems. It usually appears as lines perpendicular to the process direction of the print. Therefore, banding is an important print quality issue which has been analyzed and assessed by many researchers. However, little literature has focused on the study of the masking effect of content for this kind of print quality issue. Compared with other image and print quality research, our work is focused on the print quality of typical documents printed on a digital commercial printing press. In this paper, we propose a Masking Mediated Print Defect Visibility Predictor (MMPDVP) to predict the visibility of defects in the presence of customer content. The parameters of the algorithm are trained from ground-truth images that have been marked by subjects. The MMPDVP could help the press operator decide whether the print quality is acceptable for specific customer requirements. Ultimately, this model can be used to optimize the print-shop workflow.

  2. Reduced basis method for source mask optimization

    CERN Document Server

    Pomplun, J; Burger, S; Schmidt, F; Tyminski, J; Flagello, D; Toshiharu, N; 10.1117/12.866101


    Image modeling and simulation are critical to extending the limits of leading edge lithography technologies used for IC making. Simultaneous source mask optimization (SMO) has become an important objective in the field of computational lithography. SMO is considered essential to extending immersion lithography beyond the 45nm node. However, SMO is computationally extremely challenging and time-consuming. The key challenges are due to run time vs. accuracy tradeoffs of the imaging models used for the computational lithography. We present a new technique to be incorporated in the SMO flow. This new approach is based on the reduced basis method (RBM) applied to the simulation of light transmission through the lithography masks. It provides a rigorous approximation to the exact lithographical problem, based on fully vectorial Maxwell's equations. Using the reduced basis method, the optimization process is divided into an offline and an online steps. In the offline step, a RBM model with variable geometrical param...

  3. The Fastest Saccadic Responses Escape Visual Masking

    DEFF Research Database (Denmark)

    M. Crouzet, Sébastien; Overgaard, Morten; Busch, Niko A.


    , which gives access to very early stages of visual processing, target visibility was reduced either by OSM, conventional backward masking, or low stimulus contrast. A general reduction of performance was observed in all three conditions. However, the fastest saccades did not show any sign of interference......Object-substitution masking (OSM) occurs when a briefly presented target in a search array is surrounded by small dots that remain visible after the target disappears. The reduction of target visibility occurring after OSM has been suggested to result from a specific interference with reentrant...... visual processing while the initial feedforward processing is thought to be left intact. We tested a prediction derived from this hypothesis: the fastest responses, being triggered before the beginning of reentrant processing, should escape the OSM interference. In a saccadic choice reaction time task...

  4. Contrast Gain Control Model Fits Masking Data (United States)

    Watson, Andrew B.; Solomon, Joshua A.; Null, Cynthia H. (Technical Monitor)


    We studied the fit of a contrast gain control model to data of Foley (JOSA 1994), consisting of thresholds for a Gabor patch masked by gratings of various orientations, or by compounds of two orientations. Our general model includes models of Foley and Teo & Heeger (IEEE 1994). Our specific model used a bank of Gabor filters with octave bandwidths at 8 orientations. Excitatory and inhibitory nonlinearities were power functions with exponents of 2.4 and 2. Inhibitory pooling was broad in orientation, but narrow in spatial frequency and space. Minkowski pooling used an exponent of 4. All of the data for observer KMF were well fit by the model. We have developed a contrast gain control model that fits masking data. Unlike Foley's, our model accepts images as inputs. Unlike Teo & Heeger's, our model did not require multiple channels for different dynamic ranges.

  5. Latent inhibition in human adults without masking. (United States)

    Escobar, Martha; Arcediano, Francisco; Miller, Ralph R


    Latent inhibition refers to attenuated responding to Cue X observed when the X-outcome pairings are preceded by X-alone presentations. It has proven difficult to obtain in human adults unless the preexposure (X-alone) presentations are embedded within a masking (i.e., distracting) task. The authors hypothesized that the difficulty in obtaining latent inhibition with unmasked tasks is related to the usual training procedures, in which the preexposure and conditioning experiences are separated by a set of instructions. Experiment 1 reports latent inhibition without masking in a task in which preexposure and conditioning occur without interruption. Experiments 2 and 3 demonstrate that this attenuation in responding to target Cue X does not pass a summation test for conditioned inhibition and is context specific, thereby confirming that it is latent inhibition. Experiments 3 and 4 confirm that introducing instructions between preexposure and conditioning disrupts latent inhibition.

  6. Sinking Chao Phraya delta plain, Thailand, derived from SAR interferometry time series analysis (United States)

    Tanaka, A.; Mio, A.; Saito, Y.


    The Bangkok Metropolitan region and its surrounding provinces are located in a low-lying delta plain of the Chao Phraya River. Extensive groundwater use from the late 1950s has caused the decline of groundwater levels in the aquifers and Holocene clay compaction beneath the Bangkok Region, resulting in significant subsidence of the ground. This ground deformation has been monitored using leveling surveys since 1978, and differential InSAR (Interferometric Synthetic Aperture Radar) analysis. It shows that the Bangkok Metropolitan region is subsiding at a rate of about 20 mm/year during the recent years due to law-limited groundwater pumping, although the highest subsidence rate as high as 120 mm/year was recorded in 1981. The subsidence rate in the Bangkok area has significantly decreased since the late 1980s; however, the affected area has spread out to the surrounding areas. The maximum subsidence rate up to 30 mm/year occurred in the outlying southeast and southwest coastal zones in 2002. In this study, we apply a SAR interferometry time series analysis to monitor ground deformations in the lower Chao Phraya delta plain (Lower Central Plain), Thailand, using ALOS (Advanced Land Observing Satellite) PALSAR (Phased Array type L-band SAR) data acquired between July 2007 and September 2010. We derive a single reference time series interferogram from the stacking of unwrapped phases under the assumptions that those phases are smoothly and continuously connected, and apply a smoothness-constrained inversion algorithm that optimizes the displacement from the phase unwrapping of multitemporal differential SAR interferograms. The SAR interferometry time series analysis succeeds to monitor the incremental line-of-sight (LOS)-change between SAR scene acquisitions. LOS displacements are converted to vertical displacements, based on the assumption that the ground displacement in this area occurs only in the vertical directions. This reveals an overall pattern of subsidence

  7. Sentinel-1 TOPS interferometry for geophysical applications: Dyke intrusion imaged during 2014 Pico do Fogo eruption (United States)

    Gonzalez, Pablo J.; Marinkovic, Petar; Samsonov, Sergey; Hooper, Andrew; Larsen, Yngvar; Wright, Tim


    Since the inception of the European Space Agency ERS Synthetic Aperture Radar (SAR) mission in the 1990s, radar interferometry has become an indispensable geophysical tool for measuring surface ground deformation over wide areas with high precision. Ground deformation is a key observation to study and monitoring multiple applications in geophysics such as earthquake and tectonics, volcano, land subsidence and landslides study and monitoring. Therefore, the frequent acquisition of SAR data to compute differential interferograms is a long standing goal in observational geodesy. A new mission designed by ESA, the Sentinel-1 mission would provide routinely frequent acquisitions (every 12 days) over larger areas (250-350 km). In April 2014, the first of expected four successive and overlapping similar spacecrafts was launched to start a total 20-year continuous operational mission. Terrain observation by progressive scans (TOPS) is a new radar acquisition mode, which provides with high quality radiometric radar amplitude images. TOPS mode allows us to acquire radar data over much wider areas than previous classical stripmap mode, and it is the default mode of acquisition of ESA Sentinel-1 satellite. However, due to a variable steering (ground scanning) of the antenna pattern, the corregistration of TOPSAR images result in a much higher demanding processing step. The higher precision azimuth SAR image corregistration and variable line-of-sight along azimuth direction intersect with the fact that image disparities on the order to a thousand of a pixel size also characterizes multiple geophysical phenomena (such as landslide dynamics, coseismic earthquake, fault creep or volcanic intrusions). In this paper, we present the first results using Sentinel-1 TOPS interferometry to measure an important deformation event. We successfully compute Sentinel-1 TOPS-InSAR and tested the effect of variable line-of-sight in azimuth, during the estimation of geophysical parameters. We

  8. Spatial Hearing, Attention and Informational Masking (United States)


    0704-0188). Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing improving our understanding of the processing of streams of speech masked by other speech. 15. SUBJECT TERMS Speech intelligibility ; informational...PAGES 12 19a. NAME OF RESPONSIBLE PERSON Gerald Kidd, Jr., Ph.D. a. REPORT b. ABSTRACT c. THIS PAGE 19b. TELEPHONE NUMBER (Include area code) 617

  9. Extreme ultraviolet lithography: reflective mask technology (United States)

    Walton, Christopher C.; Kearney, Patrick A.; Mirkarimi, Paul B.; Bowers, Joel M.; Cerjan, Charles J.; Warrick, Abbie L.; Wilhelmsen, Karl C.; Fought, Eric R.; Moore, Craig E.; Larson, Cindy C.; Baker, Sherry L.; Burkhart, Scott C.; Hector, Scott D.


    EUVL mask blanks consist of a distributed Bragg reflector made of 6.7 nm-pitch bi-layers of Mo and Si deposited upon a precision Si or glass substrate. The layer deposition process has been optimized for low defects, by application of a vendor-supplied but highly modified ion-beam sputter deposition system. This system is fully automated using SMIF technology to obtain the lowest possible environmental- and handling-added defect levels. Originally designed to coat 150 mm substrates, it was upgraded in July 1999 to 200 mm and has coated runs of over 50 substrates at a time with median added defects > 100 nm below 0.05/cm2. These improvements have resulted from a number of ion-beam sputter deposition system modifications, upgrades, and operational changes, which will be discussed. Success in defect reduction is highly dependent upon defect detection, characterization, and cross- platform positional registration. We have made significant progress in adapting and extending commercial tools to this purpose, and have identified the surface scanner detection limits for different defect classes, and the signatures of false counts and non-printable scattering anomalies on the mask blank. We will present key results and how they have helped reduce added defects. The physics of defect reduction and mitigation is being investigated by a program on multilayer growth over deliberately placed perturbations (defects) of varying size. This program includes modeling of multilayer growth and modeling of defect printability. We developed a technique for depositing uniformly sized gold spheres on EUVL substrates, and have studied the suppression of the perturbations during multilayer growth under varying conditions. This work is key to determining the lower limit of critical defect size for EUV Lithography. We present key aspects of this work. We will summarize progress in all aspects of EUVL mask blank development, and present detailed results on defect reduction and mask blank

  10. Masking a Compact AES S-box (United States)


    Lecture Notes in Computer Science , pages 309–18, 2001. [2] D. Canright. A very compact S-box for AES. In CHES2005, volume 3659 of Lecture Notes in Computer Science , al., editor, CHES2003, volume 2779 of Lecture Notes in Computer Science , pages 319–333. Springer, 2003. [4] Jovan Dj. Golić and Christophe Tymen...Multiplicative masking and power analysis of AES. In CHES 2002, volume 2523 of Lecture

  11. Extreme Ultraviolet Lithography - Reflective Mask Technology

    Energy Technology Data Exchange (ETDEWEB)

    Walton, C.C.; Kearney, P.A.; Mirkarimi, P.B.; Bowers, J.M.; Cerjan, C.; Warrick, A.L.; Wilhelmsen, K.; Fought, E.; Moore, C.; Larson, C.; Baker, S.; Burkhart, S.C.; Hector, S.D.


    EUVL mask blanks consist of a distributed Bragg reflector made of 6.7nm-pitch bi-layers of MO and Si deposited upon a precision Si or glass substrate. The layer deposition process has been optimized for low defects, by application of a vendor-supplied but highly modified ion-beam sputter deposition system. This system is fully automated using SMIF technology to obtain the lowest possible environmental- and handling-added defect levels. Originally designed to coat 150mm substrates, it was upgraded in July, 1999 to 200 mm and has coated runs of over 50 substrates at a time with median added defects >100nm below 0.05/cm{sup 2}. These improvements have resulted from a number of ion-beam sputter deposition system modifications, upgrades, and operational changes, which will be discussed. Success in defect reduction is highly dependent upon defect detection, characterization, and cross-platform positional registration. We have made significant progress in adapting and extending commercial tools to this purpose, and have identified the surface scanner detection limits for different defect classes, and the signatures of false counts and non-printable scattering anomalies on the mask blank. We will present key results and how they have helped reduce added defects. The physics of defect reduction and mitigation is being investigated by a program on multilayer growth over deliberately placed perturbations (defects) of varying size. This program includes modeling of multilayer growth and modeling of defect printability. We developed a technique for depositing uniformly sized gold spheres on EUVL substrates, and have studied the suppression of the perturbations during multilayer growth under varying conditions. This work is key to determining the lower limit of critical defect size for EUV Lithography. We present key aspects of this work. We will summarize progress in all aspects of EUVL mask blank development, and present detailed results on defect reduction and mask blank

  12. Symmetry: modeling the effects of masking noise, axial cueing and salience. (United States)

    Chen, Chien-Chung; Tyler, Christopher W


    Symmetry detection is an interesting probe of pattern processing because it requires the matching of novel patterns without the benefit of prior recognition. However, there is evidence that prior knowledge of the axis location plays an important role in symmetry detection. We investigated how the prior information about the symmetry axis affects symmetry detection under noise-masking conditions. The target stimuli were random-dot displays structured to be symmetric about vertical, horizontal, or diagonal axes and viewed through eight apertures (1.2 degrees diameter) evenly distributed around a 6 degrees diameter circle. The information about axis orientation was manipulated by (1) cueing of axis orientation before the trial and (2) varying axis salience by including or excluding the axis region within the noise apertures. The percentage of correct detection of the symmetry was measured at for a range of both target and masking noise densities. The threshold vs. noise density function was flat at low noise density and increased with a slope of 0.75-0.8 beyond a critical density. Axis cueing reduced the target threshold 2-4 fold at all noise densities while axis salience had an effect only at high noise density. Our results are inconsistent with an ideal observer or signal-to-noise account of symmetry detection but can be explained by a multiple-channel model is which the response in each channel is the ratio between the nonlinear transform of the responses of sets of early symmetry detectors and the sum of external and intrinsic sources of noise.

  13. Interferometry by deconvolution of multicomponent multioffset GPR data


    Slob, E.C.


    Interferometric techniques are now well known to retrieve data between two receivers by the cross correlation of the data recorded by these receivers. Cross-correlation methods for interferometry rely mostly on the assumption that the medium is loss free and that the sources are all around the receivers. A recently developed method introduced interferometry by deconvolution that is insensitive to loss mechanisms by principle and requires sources only on one side of the receivers. In this pape...

  14. Mask image position correction for double patterning lithography (United States)

    Saito, Masato; Itoh, Masamitsu; Ikenaga, Osamu; Ishigo, Kazutaka


    Application of double patterning technique has been discussed for lithography of HP 3X nm device generation. In this case, overlay budget for lithography becomes so hard that it is difficult to achieve it with only improvement of photomask's position accuracy. One of the factors of overlay error will be induced by distortion of photomask after chucking on the mask stage of exposure tool, because photomasks are bended by the force of vacuum chucking. Recently, mask flatness prediction technique was developed. This technique is simulating the surface shape of mask when it is on the mask stage by using the flatness data of free-standing state blank and the information of mask chucking stage. To use this predicted flatness data, it is possible to predict a pattern position error after exposed and it is possible to correct it on the photomask. A blank supplier developed the flatness data transfer system to mask vender. Every blanks are distinguished individually by 2D barcode mark on blank which including serial number. The flatness data of each blank is linked with this serial number, and mask vender can use this serial number as a key code to mask flatness data. We developed mask image position correction system by using 2D barcode mark linked to predicted flatness data, and position accuracy assurance system for these masks. And with these systems, we made some masks actually.

  15. Dose masking feature for BNCT radiotherapy planning (United States)

    Cook, Jeremy L.; Wessol, Daniel E.; Wheeler, Floyd J.


    A system for displaying an accurate model of isodoses to be used in radiotherapy so that appropriate planning can be performed prior to actual treatment on a patient. The nature of the simulation of the radiotherapy planning for BNCT and Fast Neutron Therapy, etc., requires that the doses be computed in the entire volume. The "entire volume" includes the patient and beam geometries as well as the air spaces in between. Isodoses derived from the computed doses will therefore extend into the air regions between the patient and beam geometries and thus depict the unrealistic possibility that radiation deposition occurs in regions containing no physical media. This problem is solved by computing the doses for the entire geometry and then masking the physical and air regions along with the isodose contours superimposed over the patient image at the corresponding plane. The user is thus able to mask out (remove) the contour lines from the unwanted areas of the image by selecting the appropriate contour masking region from the raster image.

  16. 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


    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.

  17. Contact printed masks for 3D microfabrication in negative resists

    DEFF Research Database (Denmark)

    Häfliger, Daniel; Boisen, Anja


    We present a process based on contact printed shadow masks for three dimensional microfabrication of soft and sensitive overhanging membranes in SU-8. A metal mask is transferred onto unexposed SU-8 from an elastomer stamp made of polydimethylsiloxane. This mask is subsequently embedded into the ......We present a process based on contact printed shadow masks for three dimensional microfabrication of soft and sensitive overhanging membranes in SU-8. A metal mask is transferred onto unexposed SU-8 from an elastomer stamp made of polydimethylsiloxane. This mask is subsequently embedded...... into the negative resist to protect buried material from UV-exposure. Unlike direct evaporation-deposition of a mask onto the SU-8, printing avoids high stress and radiation, thus preventing resist wrinkling and prepolymerization. We demonstrate effective monolithic fabrication of soft, 4-μm thick and 100-μm long...

  18. Mask design rules (45 nm): time for standardization (United States)

    Mason, Mark; Progler, Christopher J.; Martin, Patrick; Ham, Young-Mog; Dillon, Brian; Pack, Robert; Heins, Mitch; Gookassian, John; Garcia, John; Boksha, Victor


    Time-to-mask (ttm) has been growing exponentially in the subwavelength era with the increased application of advanced RET's (Resolution Enhancement Technology). Not only are a greater number of design/mask layers impacted but more-and-more layers also have more severe restrictions on critical dimension uniformity (CDU) despite operating at a very low k1 factors necessitating rigorous but practical tolerancing. Furthermore, designs are also more complex, may be built up from blocks spanning different design styles, and occupy increasingly-large Rayleigh field areas. Given these factors and scales, it's no wonder that the cycle time for verification of a design following RET, is growing however it is doing so exponentially and that this is a critical factor impeding ttm. Until an unambiguously interprable and standard Mask Design Rule (MaskDR) set is created, neither the designer nor the mask supplier can reliably verify manufacturability of the mask for the simple reason that ambiguity and inter-rule conflict are at the source of the problem and that the problem increasingly requires cooperation spanning a large ecosystem of tool, IP, and mask suppliers all needing to essentially speak the same language. Since the 130 nm node, Texas Instruments has enforced a strict set of mask rule checks (MRCs) in their mask data preparation (MDP) flow based on MaskDRs negotiated with their mask suppliers. The purpose of this effort has been to provide an a-priori guarantee that the data shipped to the mask shop can be used to manufacture a mask reliably and with high yield both from a mask standpoint and from the silicon standpoint. As has been reported earlier, mask manufacturing rules are usually determined from assumed or experimentally acquired/validated mask-manufacturing limits. These rules are then applied during RET/MDP data treatment to guide and/or limit pattern correction strategies. With increasing RET and low-k1 lithography challenges, the importance of MRCs

  19. Optical thickness measurement of mask blank glass plate by the excess fraction method using a wavelength-tuning interferometer (United States)

    Kim, Yangjin; Hibino, Kenichi; Sugita, Naohiko; Mitsuishi, Mamoru


    The absolute optical thickness of a 140-mm2 mask blank glass plate 3.1 mm thickness was measured by three-surface interferometry using a wavelength-tuning Fizeau interferometer. The interference order was determined by the excess fraction method. The wavelength of a tunable laser diode was scanned linearly from 632 to 642 nm, and a CCD detector recorded 2000 interference images. Two kinds of optical thicknesses measured by discrete Fourier analysis and phase-shifting were synthesized to obtain the optical thickness with respect to the ordinary refractive index. The optical thickness defined by the group refractive index at the 637 nm central wavelength was measured by wavelength scanning. The optical thickness deviation defined by the ordinary refractive index was measured using tunable phase-shifting. The systematic errors caused by nonlinearity in the wavelength tuning were corrected through correlation analysis between the theoretical and observed interference fringes.

  20. Precise slit-width control of niobium apertures for superconducting LEDs. (United States)

    Huh, Jae-Hoon; Hermannstädter, Claus; Sato, Hiroyasu; Ito, Saki; Idutsu, Yasuhiro; Sasakura, Hirotaka; Tanaka, Kazunori; Akazaki, Tatsushi; Suemune, Ikuo


    We introduce a novel three-step procedure for precise niobium (Nb)-etching on the nanometer-scale, including the design of high contrast resist patterning and sacrifice layer formation under high radio frequency (RF) power. We present the results of precise slit fabrication using this technique and discuss its application for the production of superconducting devices, such as superconductor-semiconductor-superconductor (S-Sm-S) Josephson junctions. For the reactive ion etching (RIE) of Nb, we selected CF(4) as etchant gas and a positive tone resist to form the etching mask. We found that the combination of resist usage and RIE process allows for etching of thicker Nb layers when utilizing the opposite dependence of the etching rate (ER) on the CF(4) pressure in the case of Nb as compared to the resist. Precise slit-width control of 80 and 200 nm thick Nb apertures was performed with three kinds of ER control, for the resist, the Nb, and the underlying layer. S-Sm-S Josephson junctions were fabricated with lengths as small as 80 nm, which can be considered clean and short and thus exhibit critical currents as high as 50 µA. Moreover, possible further applications, such as for apertures of superconducting light emitting diodes (SC LEDs), are addressed.

  1. A study on the factors that affect the advanced mask defect verification (United States)

    Woo, Sungha; Jang, Heeyeon; Lee, Youngmo; Kim, Sangpyo; Yim, Donggyu


    Defect verification has become significantly difficult to higher technology nodes over the years. Traditional primary method of defect (include repair point) control consists of inspection, AIMS and repair steps. Among them, AIMS process needs various wafer lithography conditions, such as NA, inner/outer sigma, illumination shape and etc. It has a limit to analyze for every layer accurately because AIMS tool uses the physical aperture system. And it requires meticulous management of exposure condition and CD target value which change frequently in advanced mask. We report on the influence of several AIMS parameters on the defect analysis including repair point. Under various illumination conditions with different patterns, it showed the significant correlation in defect analysis results. It is able to analyze defect under certain error budget based on the management specification required for each layer. In addition, it provided us with one of the clues in the analysis of wafer repeating defect. Finally we will present 'optimal specification' for defect management with common AIMS recipe and suggest advanced mask process flow.

  2. The physics of light transmission through subwavelength apertures and aperture arrays (United States)

    Weiner, J.


    The passage of light through apertures much smaller than the wavelength of the light has proved to be a surprisingly subtle phenomenon. This report describes how modern developments in nanofabrication, coherent light sources and numerical vector field simulations have led to the upending of early predictions from scalar diffraction theory and classical electrodynamics. Optical response of real materials to incident coherent radiation at petahertz frequencies leads to unexpected consequences for transmission and extinction of light through subwavelength aperture arrays. This paper is a report on progress in our understanding of this phenomenon over the past decade.

  3. The masked priming toolbox: an open-source MATLAB toolbox for masked priming researchers. (United States)

    Wilson, Andrew D; Tresilian, James; Schlaghecken, Friederike


    The Masked Priming Toolbox is an open-source collection of MATLAB functions that utilizes the free third-party PsychToolbox-3 (PTB3: Brainard, Spatial Vision, 10, 433-436, 1997; Kleiner, Brainard & Pelli, Perception, 36, 2007; Pelli, Spatial Vision, 10, 437-442, 1997). It is designed to allow a researcher to run masked (and unmasked) priming experiments using a variety of response devices (including keyboards, graphics tablets and force transducers). Very little knowledge of MATLAB is required; experiments are generated by creating a text file with the required parameters, and raw and analyzed data are output to Excel (as well as MATLAB) files for further analysis. The toolbox implements a variety of stimuli for use as primes and targets, as well as a variety of masks. Timing, size, location, and orientation of stimuli are all parameterizable. The code is open-source and made available on the Web under a Creative Commons License.

  4. Multi-beam mask writer MBM-1000 and its application field (United States)

    Matsumoto, Hiroshi; Inoue, Hideo; Yamashita, Hiroshi; Morita, Hirofumi; Hirose, Satoru; Ogasawara, Munehiro; Yamada, Hirokazu; Hattori, Kiyoshi


    NuFlare has started development of multi-beam mask writer MBM-1000 aiming to apply to N5 and to release in Q4 2017. MBM-1000 is based on large area projection optics with shaping aperture array plate, blanking aperture array (BAA) plate, single cathode and inline/realtime data path for vector data rasterization and bitmap dose correction. It is designed to accomplish higher throughput than EBM series (variable shaped beam (VSB) writers) with massive beam array, higher resolution by using 10-nm beam size and 10-bit dose control, and better writing accuracy with more write passes. Configuration of MBM-1000 and flow of data path processing are described. Write time estimation suggests MBM-1000 has advantage over VSB writer with shot count > 200 Gshot/pass and resist sensitivity >75 μC/cm2. Printing test of 20 nm hp 1:1 line and space pattern with ZEP-520 resist showed better beam resolution of MBM-1000 alpha tool than EBM series.

  5. Demonstrators: a vital step forward for projection mask-less lithography (PML2) (United States)

    Brandstaetter, Christoph; Haugeneder, Ernst; Doering, Hans-Joachim; Elster, Thomas; Heinitz, Joachim; Fortagne, Olaf; Eder-Kapl, Stefan; Lammer, Gertraud; Jochl, Peter; Loeschner, Hans; Reimer, Klaus; Saniter, Juergen; Talmi, Maati; Eberhardt, Ramona; Kroenert, Klaus


    Electron beam based Projection Mask-Less Lithography (PML2) is one of the promising candidates for fast chip devel-opment and prototyping as well as for small and medium volume device production for the 45nm technology node and beyond. The concept of the PML2 proof-of-concept tool comprises a single electron optical column, a multi beam blank-ing device (programmable "Aperture Plate System") including high speed optical data path and a scanning 300mm wa-fer stage. More than 290.000 beams will be projected onto the wafer used for a highly redundant scanning stripe expo-sure process. The PML2 proof-of-concept tool will be built as part of the European MEDEA+ project T409 and the joint project "Ab-bildungsmethodiken fur nanoelektronische Bauelemente-ABBILD" in Germany. To show the feasibility of PML2 key modules in an early stage several demonstrators and test stands have been developed. In this paper demonstration setups and first results of the electron optics modeling, gun prototype, Aperture Plate System and the Optical Data Path are pre-sented.

  6. SU-C-201-03: Coded Aperture Gamma-Ray Imaging Using Pixelated Semiconductor Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, S [Wayne State University, Detroit, MI (United States); Kaye, W; Jaworski, J [H3D, Inc., Ann Arbor, MI (United States); He, Z [University of Michigan, Ann Arbor, MI (United States)


    Purpose: Improved localization of gamma-ray emissions from radiotracers is essential to the progress of nuclear medicine. Polaris is a portable, room-temperature operated gamma-ray imaging spectrometer composed of two 3×3 arrays of thick CdZnTe (CZT) detectors, which detect gammas between 30keV and 3MeV with energy resolution of <1% FWHM at 662keV. Compton imaging is used to map out source distributions in 4-pi space; however, is only effective above 300keV where Compton scatter is dominant. This work extends imaging to photoelectric energies (<300keV) using coded aperture imaging (CAI), which is essential for localization of Tc-99m (140keV). Methods: CAI, similar to the pinhole camera, relies on an attenuating mask, with open/closed elements, placed between the source and position-sensitive detectors. Partial attenuation of the source results in a “shadow” or count distribution that closely matches a portion of the mask pattern. Ideally, each source direction corresponds to a unique count distribution. Using backprojection reconstruction, the source direction is determined within the field of view. The knowledge of 3D position of interaction results in improved image quality. Results: Using a single array of detectors, a coded aperture mask, and multiple Co-57 (122keV) point sources, image reconstruction is performed in real-time, on an event-by-event basis, resulting in images with an angular resolution of ∼6 degrees. Although material nonuniformities contribute to image degradation, the superposition of images from individual detectors results in improved SNR. CAI was integrated with Compton imaging for a seamless transition between energy regimes. Conclusion: For the first time, CAI has been applied to thick, 3D position sensitive CZT detectors. Real-time, combined CAI and Compton imaging is performed using two 3×3 detector arrays, resulting in a source distribution in space. This system has been commercialized by H3D, Inc. and is being acquired for

  7. Strategy optimization for mask rule check in wafer fab (United States)

    Yang, Chuen Huei; Lin, Shaina; Lin, Roger; Wang, Alice; Lee, Rachel; Deng, Erwin


    Photolithography process is getting more and more sophisticated for wafer production following Moore's law. Therefore, for wafer fab, consolidated and close cooperation with mask house is a key to achieve silicon wafer success. However, generally speaking, it is not easy to preserve such partnership because many engineering efforts and frequent communication are indispensable. The inattentive connection is obvious in mask rule check (MRC). Mask houses will do their own MRC at job deck stage, but the checking is only for identification of mask process limitation including writing, etching, inspection, metrology, etc. No further checking in terms of wafer process concerned mask data errors will be implemented after data files of whole mask are composed in mask house. There are still many potential data errors even post-OPC verification has been done for main circuits. What mentioned here are the kinds of errors which will only occur as main circuits combined with frame and dummy patterns to form whole reticle. Therefore, strategy optimization is on-going in UMC to evaluate MRC especially for wafer fab concerned errors. The prerequisite is that no impact on mask delivery cycle time even adding this extra checking. A full-mask checking based on job deck in gds or oasis format is necessary in order to secure acceptable run time. Form of the summarized error report generated by this checking is also crucial because user friendly interface will shorten engineers' judgment time to release mask for writing. This paper will survey the key factors of MRC in wafer fab.

  8. Source mask optimization using 3D mask and compact resist models (United States)

    El-Sewefy, Omar; Chen, Ao; Lafferty, Neal; Meiring, Jason; Chung, Angeline; Foong, Yee Mei; Adam, Kostas; Sturtevant, John


    Source Mask Optimization (SMO) has played an important role in technology setup and ground rule definition since the 2x nm technology node. While improvements in SMO algorithms have produced higher quality and more consistent results, the accuracy of the overall solution is critically linked to how faithfully the entire patterning system is modeled, from mask down to substrate. Fortunately, modeling technology has continued to advance to provide greater accuracy in modeling 3D mask effects, 3D resist behavior, and resist phenomena. Specifically, the Domain Decomposition Method (DDM) approximates the 3D mask response as a superposition of edge-responses.1 The DDM can be applied to a sectorized illumination source based on Hybrid-Hopkins Abbe approximation,2 which provides an accurate and fast solution for the modeling of 3D mask effects and has been widely used in OPC modeling. The implementation of DDM in the SMO flow, however, is more challenging because the shape and intensity of the source, unlike the case in OPC modeling, is evolving along the optimization path. As a result, it gets more complicated. It is accepted that inadequate pupil sectorization results in reduced accuracy in any application, however in SMO the required uniformity and density of pupil sampling is higher than typical OPC and modeling cases. In this paper, we describe a novel method to implement DDM in the SMO flow. The source sectorization is defined by following the universal pixel sizes used in SMO. Fast algorithms are developed to enable computation of edge signals from each fine pixel of the source. In this case, each pixel has accurate information to describe its contribution to imaging and the overall objective function. A more continuous angular spectrum from 3D mask scattering is thus captured, leading to accurate modeling of 3D mask effects throughout source optimization. This method is applied on a 2x nm middle-of-line layer test case. The impact of the 3D mask model accuracy on

  9. Women and trauma: transformation of self through mask making and action-based mask work


    Birch, June Elizabeth


    This secondary analysis study examined the stories of six women who were impacted by trauma. These women attended a ten-week counselling group in which they participated in the construction of masks and in action-based mask work as a means of expressing and working through their trauma experiences. Based on a constructivist approach, the methodology employed in this study was a narrative inquiry centred on the work of Lieblich, Tuval-Mashiach, and Zilber (1998). The data were generated from o...

  10. The Configurable Aperture Space Telescope (CAST) (United States)

    Ennico, Kimberly; Bendek, Eduardo A.; Lynch, Dana H.; Vassigh, Kenny K.; Young, Zion


    The Configurable Aperture Space Telescope, CAST, is a concept that provides access to a UV/visible-infrared wavelength sub-arcsecond imaging platform from space, something that will be in high demand after the retirement of the astronomy workhorse, the 2.4 meter diameter Hubble Space Telescope. CAST allows building large aperture telescopes based on small, compatible and low-cost segments mounted on autonomous cube-sized satellites. The concept merges existing technology (segmented telescope architecture) with emerging technology (smartly interconnected modular spacecraft, active optics, deployable structures). Requiring identical mirror segments, CAST's optical design is a spherical primary and secondary mirror telescope with modular multi-mirror correctors placed at the system focal plane. The design enables wide fields of view, up to as much as three degrees, while maintaining aperture growth and image performance requirements. We present a point design for the CAST concept based on a 0.6 meter diameter (3 x 3 segments) growing to a 2.6 meter diameter (13 x 13 segments) primary, with a fixed Rp=13,000 and Rs=8,750 mm curvature, f/22.4 and f/5.6, respectively. Its diffraction limited design uses a two arcminute field of view corrector with a 7.4 arcsec/mm platescale, and can support a range of platescales as fine as 0.01 arcsec/mm. Our paper summarizes CAST, presents a strawman optical design and requirements for the underlying modular spacecraft, highlights design flexibilities, and illustrates applications enabled by this new method in building space observatories.

  11. Practical use of the repeating patterns in mask writing (United States)

    Shoji, Masahiro; Inoue, Tadao; Yamabe, Masaki


    In May 2006, the Mask Design, Drawing, and Inspection Technology Research Department (Mask D2I) at the Association of Super-Advanced Electronics Technologies (ASET) launched a 4-year program for reducing mask manufacturing cost and TAT by concurrent optimization of MDP, mask writing, and mask inspection. As one of the tasks being pursued at the Mask Design Data Technology Research Laboratory, we have evaluated the effect of reducing the drawing shot counts by utilizing the repeating patterns, and showed positive impact on mask making by using CP drawing. During the past four years, we have developed a software to extract repeating patterns from fractured OPCed mask data which can be used to minimize the shot counts. In this evaluation, we have used an actual device production data obtained from the member companies of MaskD2I. To the extraction software we added new functions for extracting common repeating patterns from a set of multiple masks, and studied how this step can reduce the counts in comparison to the shot counts required during the conventional mask writing techniques. We have also developed software that uses the extraction result of repeating patterns and prepares drawing-data for the MCC/CP drawing system, which has been developed at the Mask Writing Equipment Technology Research Laboratory. With this software, we have simulated EB proximity effect on CP writing and examined how it affect the shot count reduction where CP shots with large CD errors are to be divided into VSB shots. In this paper, we will report the evaluation result of the practical application of repeating patterns in mask writing with this software.

  12. Synthetic aperture radar autofocus via semidefinite relaxation. (United States)

    Liu, Kuang-Hung; Wiesel, Ami; Munson, David C


    The autofocus problem in synthetic aperture radar imaging amounts to estimating unknown phase errors caused by unknown platform or target motion. At the heart of three state-of-the-art autofocus algorithms, namely, phase gradient autofocus, multichannel autofocus (MCA), and Fourier-domain multichannel autofocus (FMCA), is the solution of a constant modulus quadratic program (CMQP). Currently, these algorithms solve a CMQP by using an eigenvalue relaxation approach. We propose an alternative relaxation approach based on semidefinite programming, which has recently attracted considerable attention in other signal processing problems. Experimental results show that our proposed methods provide promising performance improvements for MCA and FMCA through an increase in computational complexity.

  13. Tissue Harmonic Synthetic Aperture Ultrasound Imaging

    DEFF Research Database (Denmark)

    Hemmsen, Martin Christian; Rasmussen, Joachim; Jensen, Jørgen Arendt


    Synthetic aperture sequential beamforming (SASB) and tissue har- monic imaging (THI) are combined to improve the image quality of medical ultrasound imaging. The technique is evaluated in a compar- ative study against dynamic receive focusing (DRF). The objective is to investigate if SASB combined......, and data were recorded with and without pulse inversion for tissue harmonic imaging. Data were acquired using a Sound Technol- ogy 192 element convex array transducer from both a wire phantom and a tissue mimicking phantom to investigate spatial resolution and pen- etration. In-vivo scans were also...

  14. VELO aperture considerations for the LHCb Upgrade

    CERN Document Server

    Appleby, R B; Giovannozzi, M; Holzer, B; Neat, M


    In Long Shutdown 2 the VELO detectors will be replaced by new modules compatible with the LHCb Upgrade 40 MHz read-out system. A smaller inner radius of the VELO RF foil and of the silicon sensor active area will allow LHCb to considerably improve the impact parameter resolution. Here, a limit of the minimum VELO aperture during physics (Stable Beams) is discussed. A value of 3.5 mm for the nominal radius of the inner edge fo the RF foil seems acceptable.

  15. Synthetic Aperture Imaging in Medical Ultrasound

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Gammelmark, Kim; Pedersen, Morten


    with high precision, and the imaging is easily extended to real-time 3D scanning. This paper presents the work done at the Center for Fast Ultrasound Imaging in the area of SA imaging. Three areas that benefit from SA imaging are described. Firstly a preliminary in-vivo evaluation comparing conventional B......Synthetic Aperture (SA) ultrasound imaging is a relatively new and unexploited imaging technique. The images are perfectly focused both in transmit and receive, and have a better resolution and higher dynamic range than conventional ultrasound images. The blood flow can be estimated from SA images...

  16. Combined synthetic aperture radar/Landsat imagery (United States)

    Marque, R. E.; Maurer, H. E.


    This paper presents the results of investigations into merging synthetic aperture radar (SAR) and Landsat multispectral scanner (MSS) images using optical and digital merging techniques. The unique characteristics of airborne and orbital SAR and Landsat MSS imagery are discussed. The case for merging the imagery is presented and tradeoffs between optical and digital merging techniques explored. Examples of Landsat and airborne SAR imagery are used to illustrate optical and digital merging. Analysis of the merged digital imagery illustrates the improved interpretability resulting from combining the outputs from the two sensor systems.

  17. Acoustics of finite-aperture vortex beams

    CERN Document Server

    Mitri, F G


    A method based on the Rayleigh-Sommerfeld surface integral is provided, which makes it feasible to rigorously model, evaluate and compute the acoustic scattering and other mechanical effects of finite-aperture vortex beams such as the acoustic radiation force and torque on a viscoelastic sphere in various applications in acoustic tweezers and microfluidics, particle entrapment, manipulation and rotation. Partial-wave series expansions are derived for the incident field of acoustic spiraling (vortex) beams, comprising high-order Bessel and Bessel-Gauss beams.

  18. Generic hierarchical engine for mask data preparation (United States)

    Kalus, Christian K.; Roessl, Wolfgang; Schnitker, Uwe; Simecek, Michal


    Electronic layouts are usually flattened on their path from the hierarchical source downstream to the wafer. Mask data preparation has certainly been identified as a severe bottleneck since long. Data volumes are not only doubling every year along the ITRS roadmap. With the advent of optical proximity correction and phase-shifting masks data volumes are escalating up to non-manageable heights. Hierarchical treatment is one of the most powerful means to keep memory and CPU consumption in reasonable ranges. Only recently, however, has this technique acquired more public attention. Mask data preparation is the most critical area calling for a sound infrastructure to reduce the handling problem. Gaining more and more attention though, are other applications such as large area simulation and manufacturing rule checking (MRC). They all would profit from a generic engine capable to efficiently treat hierarchical data. In this paper we will present a generic engine for hierarchical treatment which solves the major problem, steady transitions along cell borders. Several alternatives exist how to walk through the hierarchy tree. They have, to date, not been thoroughly investigated. One is a bottom-up attempt to treat cells starting with the most elementary cells. The other one is a top-down approach which lends itself to creating a new hierarchy tree. In addition, since the variety, degree of hierarchy and quality of layouts extends over a wide range a generic engine has to take intelligent decisions when exploding the hierarchy tree. Several applications will be shown, in particular how far the limits can be pushed with the current hierarchical engine.

  19. Crowding is unlike ordinary masking: distinguishing feature integration from detection. (United States)

    Pelli, Denis G; Palomares, Melanie; Majaj, Najib J


    A letter in the peripheral visual field is much harder to identify in the presence of nearby letters. This is "crowding." Both crowding and ordinary masking are special cases of "masking," which, in general, refers to any effect of a "mask" pattern on the discriminability of a signal. Here we characterize crowding, and propose a diagnostic test to distinguish it from ordinary masking. In ordinary masking, the signal disappears. In crowding, it remains visible, but is ambiguous, jumbled with its neighbors. Masks are usually effective only if they overlap the signal, but the crowding effect extends over a large region. The width of that region is proportional to signal eccentricity from the fovea and independent of signal size, mask size, mask contrast, signal and mask font, and number of masks. At 4 deg eccentricity, the threshold contrast for identification of a 0.32 deg signal letter is elevated (up to six-fold) by mask letters anywhere in a 2.3 deg region, 7 times wider than the signal. In ordinary masking, threshold contrast rises as a power function of mask contrast, with a shallow log-log slope of 0.5 to 1, whereas, in crowding, threshold is a sigmoidal function of mask contrast, with a steep log-log slope of 2 at close spacing. Most remarkably, although the threshold elevation decreases exponentially with spacing, the threshold and saturation contrasts of crowding are independent of spacing. Finally, ordinary masking is similar for detection and identification, but crowding occurs only for identification, not detection. More precisely, crowding occurs only in tasks that cannot be done based on a single detection by coarsely coded feature detectors. These results (and observers' introspections) suggest that ordinary masking blocks feature detection, so the signal disappears, while crowding (like "illusory conjunction") is excessive feature integration - detected features are integrated over an inappropriately large area because there are no smaller integration

  20. Aperture Effects and Mismatch Oscillations in an Intense Electron Beam

    Energy Technology Data Exchange (ETDEWEB)

    Harris, J R; O' Shea, P G


    When an electron beam is apertured, the transmitted beam current is the product of the incident beam current density and the aperture area. Space charge forces generally cause an increase in incident beam current to result in an increase in incident beam spot size. Under certain circumstances, the spot size will increase faster than the current, resulting in a decrease in current extracted from the aperture. When using a gridded electron gun, this can give rise to negative transconductance. In this paper, we explore this effect in the case of an intense beam propagating in a uniform focusing channel. We show that proper placement of the aperture can decouple the current extracted from the aperture from fluctuations in the source current, and that apertures can serve to alter longitudinal space charge wave propagation by changing the relative contribution of velocity and current modulation present in the beam.

  1. Defectivity and particle reduction for mask life extension, and imprint mask replication for high-volume semiconductor manufacturing (United States)

    Emoto, Keiji; Sakai, Fumio; Sato, Chiaki; Takabayashi, Yukio; Nakano, Hitoshi; Takabayashi, Tsuneo; Yamamoto, Kiyohito; Hattori, Tadashi; Hiura, Mitsuru; Ando, Toshiaki; Kawanobe, Yoshio; Azuma, Hisanobu; Iwanaga, Takehiko; Choi, Jin; Aghili, Ali; Jones, Chris; Irving, J. W.; Fletcher, Brian; Ye, Zhengmao


    Imprint lithography has been shown to be an effective technique for replication of nano-scale features. Jet and Flash* Imprint Lithography (J-FIL*) involves the field-by-field deposition and exposure of a low viscosity resist deposited by jetting technology onto the substrate. The patterned mask is lowered into the fluid which then quickly flows into the relief patterns in the mask by capillary action. Following this filling step, the resist is crosslinked under UV radiation, and then the mask is removed, leaving a patterned resist on the substrate. Criteria specific to any lithographic process for the semiconductor industry include overlay, throughput and defectivity. The purpose of this paper is to describe the technology advancements made in the reduction of particle adders in an imprint tool and introduce the new mask replication tool that will enable the fabrication of replica masks with added residual image placement errors suitable for memory devices with half pitches smaller than 15nm. Hard particles on a wafer or mask create the possibility of creating a permanent defect on the mask that can impact device yield and mask life. By using material methods to reduce particle shedding and by introducing an air curtain system, test stand results demonstrate the potential for extending mask life to better than 1000 wafers. Additionally, a new replication tool, the FPA-1100 NR2 is introduced. Mask chuck flatness simulation results were also performed and demonstrate that residual image placement errors can be reduced to as little as 1nm.

  2. Model-based virtual VSB mask writer verification for efficient mask error checking and optimization prior to MDP (United States)

    Pack, Robert C.; Standiford, Keith; Lukanc, Todd; Ning, Guo Xiang; Verma, Piyush; Batarseh, Fadi; Chua, Gek Soon; Fujimura, Akira; Pang, Linyong


    A methodology is described wherein a calibrated model-based `Virtual' Variable Shaped Beam (VSB) mask writer process simulator is used to accurately verify complex Optical Proximity Correction (OPC) and Inverse Lithography Technology (ILT) mask designs prior to Mask Data Preparation (MDP) and mask fabrication. This type of verification addresses physical effects which occur in mask writing that may impact lithographic printing fidelity and variability. The work described here is motivated by requirements for extreme accuracy and control of variations for today's most demanding IC products. These extreme demands necessitate careful and detailed analysis of all potential sources of uncompensated error or variation and extreme control of these at each stage of the integrated OPC/ MDP/ Mask/ silicon lithography flow. The important potential sources of variation we focus on here originate on the basis of VSB mask writer physics and other errors inherent in the mask writing process. The deposited electron beam dose distribution may be examined in a manner similar to optical lithography aerial image analysis and image edge log-slope analysis. This approach enables one to catch, grade, and mitigate problems early and thus reduce the likelihood for costly long-loop iterations between OPC, MDP, and wafer fabrication flows. It moreover describes how to detect regions of a layout or mask where hotspots may occur or where the robustness to intrinsic variations may be improved by modification to the OPC, choice of mask technology, or by judicious design of VSB shots and dose assignment.

  3. Silicon germanium mask for deep silicon etching

    KAUST Repository

    Serry, Mohamed


    Polycrystalline silicon germanium (SiGe) can offer excellent etch selectivity to silicon during cryogenic deep reactive ion etching in an SF.sub.6/O.sub.2 plasma. Etch selectivity of over 800:1 (Si:SiGe) may be achieved at etch temperatures from -80 degrees Celsius to -140 degrees Celsius. High aspect ratio structures with high resolution may be patterned into Si substrates using SiGe as a hard mask layer for construction of microelectromechanical systems (MEMS) devices and semiconductor devices.

  4. Computer-assisted area detector masking. (United States)

    Wright, Christopher J; Zhou, Xiao Dong


    Area detectors have become the predominant type of detector for the rapid acquisition of X-ray diffraction, small-angle scattering and total scattering. These detectors record the scattering for a large area, giving each shot good statistical significance to the resulting scattered intensity I(Q) pattern. However, many of these detectors have pixel level defects, which cause error in the resulting one-dimensional patterns. In this work, new software to automatically find and mask these dead pixels and other defects is presented. This algorithm is benchmarked with both ideal simulated and experimental datasets.

  5. Revolution with and without the mask

    Directory of Open Access Journals (Sweden)

    Milanko Vladan


    Full Text Available This paper is an attempt to provide a certain “second reading” of those commonplaces which imply that a particular, personal interest always lies behind the mask of objectivity, necessity and truth. As a paradigmatic example of this kind of structure that implies “hidden truths”, here will be taken that of a revolution, whether it is a fascist, a liberal-democratic or a communist revolution. By reexamining how this motif of “truth-behind-the-mask” figures in those regimes, we will try to say something about each of them, and also about the specific kind of subject that is produced under them.

  6. Vibration-resistant phase retrieval method with contrast compensation for phase-shifting interferometry (United States)

    Liu, Qian; He, Huabin; Yuan, Daocheng; He, Jianguo; Ji, Fang


    Vibration hinders the application of phase-shifting interferometry (PSI) to on-machine test and large-aperture mirror measurement. The investigation of PSI fringe disturbed by vibration indicates that, besides tilt-shifting error, inter- and intra-frame contrast variation is significant. The contrast variation is another dominant error source in phase retrieval of PSI. An inter- and intra-frame contrast compensation method is proposed here to retrieve wavefront phase from interferograms subjected to vibration. The method constructs algebraic equations with interferogram data and solves equations using iterative procedures. Experiments validate its effectiveness and manifest its capability to suppress vibration-induced error over a large frequency region. To enhance the calculation efficiency, a spatial subsampling strategy is proposed. Practical testing shows that subsampling reduces calculation time exponentially and preserves retrieval accuracy and spatial resolution. The proposed method, of which the unique ability is compensating the tilt-shifting error and fringe blur caused by vibration, predicates an effective and low-cost solution for PSI applied in vibration.

  7. TanDEM-X Across-Track Interferometry over Dry Snow Covered Terrain (United States)

    Panagiotopoulou, Dimitra; Brown, Ian A.


    We analyse bistatic HH-polarised TanDEM-X interferometric synthetic aperture radar (InSAR) data acquired over winter, dry snow conditions in a sub- Arctic site in Norway. Exploiting the principles of across-track interferometry, the elevation of the scattering phase centre estimated by the phase difference between the two SAR acquisitions. Interference patterns were assessed both qualitatively and quantitatively. Clearings and forest stands, were analysed. Interferometric phase uncertainty and spatio-temporal consistency were analysed by means of scattering phase centre elevation accuracy and coherence degree, γ with respect to hydro-meteorological conditions. Clearings displayed absolute height errors of < 1 m. The sole approximation was to consider volume decorrelation effects as main source of elevation ambiguities and coherence decay. Principal Component Analysis was conducted to identify the combined influence of variables describing the radar response and scattering centre. However, the derived DEMs attained high vertical accuracy, the sub-meter height errors might relate to snowcover effects. Coherence was strongly influenced by snowpack parameters suggesting TDM coherence inversion may enable snow cover monitoring.

  8. Observing hourly changes in a glacier's surface with Terrestrial Radar Interferometry (United States)

    Voytenko, D.; Dixon, T. H.; Osmanoglu, B.; Werner, C. L.; Howat, I. M.


    Capturing rapid changes in the surface of a glacier requires frequent observations. Terrestrial Radar Interferometry (TRI) is a new technique that relies on a portable, ground-based radar to image the terminal zones of glaciers up to 10 km from the calving front. TRI offers denser spatial sampling than GPS and higher temporal sampling than satellite SAR, making it an excellent tool to monitor fast-moving glaciers. This study focuses on developing methods to generate robust topographic and deformation maps with TRI. Breidamerkurjokull is a fast-moving glacier in southeastern Iceland with summer velocities as high as 4 m/d at the calving front. The glacier terminates at, and continuously calves icebergs into, a tidally-influenced lagoon. To better understand its dynamics, we image the glacier with the GAMMA Portable Radar Interferometer (GPRI). The GPRI is a Ku-band real-aperture radar with one transmitting and two receiving antennas. The configuration of the receiving antennas allows estimates of glacier topography with each subsequent image acquisition along with a deformation map, since the baseline between the antennas is known and fixed. We will present results that show the temporal evolution of the glacier's surface over a period of approximately one week, including volumetric ice change estimates for the imaged area.


    Directory of Open Access Journals (Sweden)

    Noorlaila Hayati


    Full Text Available This paper reviewed the result and processing of digital elevation model (DEM using L-Band ALOS PALSAR data and two-pass radar interferometry method in Bromo Mountain region. Synthetic Aperture Radar is an advanced technology that has been used to monitor deformation, land cover change, image detection and especially topographic information such as DEM.  We used two scenes of SAR imageries to generate DEM extraction which assumed there is no deformation effect between two acquisitions. We could derive topographic information using phase difference by combining two single looks complex (SLC images called focusing process. The next steps were doing interferogram generation, phase unwrapping and geocoding. DEM-InSAR was compared to SRTM 90m that there were significant elevation differences between two DEMs such as smoothing surface and detail topographic. Particularly for hilly areas, DEM-InSAR showed better quality than SRTM 90 m where the elevation could have 25.94 m maximum gap. Although the processing involved adaptive filter to amplify the phase signal, we concluded that InSAR DEM result still had error noise because of signal wavelength, incidence angle, SAR image relationship, and only using ascending orbit direction.

  10. Nulling interferometry: impact of exozodiacal clouds on the performance of future life-finding space missions

    CERN Document Server

    Defrère, D; Hartog, R den; Hanot, C; Stark, C; 10.1051/0004-6361/200912973


    Earth-sized planets around nearby stars are being detected for the first time by ground-based radial velocity and space-based transit surveys. This milestone is opening the path towards the definition of missions able to directly detect the light from these planets, with the identification of bio-signatures as one of the main objectives. In that respect, both ESA and NASA have identified nulling interferometry as one of the most promising techniques. The ability to study distant planets will however depend on exozodiacal dust clouds surrounding the target stars. In this paper, we assess the impact of exozodiacal dust clouds on the performance of an infrared nulling interferometer in the Emma X-array configuration. For the nominal mission architecture with 2-m aperture telescopes, we found that point-symmetric exozodiacal dust discs about 100 times denser than the solar zodiacal cloud can be tolerated in order to survey at least 150 targets during the mission lifetime. Considering modeled resonant structures c...

  11. Radar interferometry offers new insights into threats to the Angkor site (United States)

    Chen, Fulong; Guo, Huadong; Ma, Peifeng; Lin, Hui; Wang, Cheng; Ishwaran, Natarajan; Hang, Peou


    The conservation of World Heritage is critical to the cultural and social sustainability of regions and nations. Risk monitoring and preventive diagnosis of threats to heritage sites in any given ecosystem are a complex and challenging task. Taking advantage of the performance of Earth Observation technologies, we measured the impacts of hitherto imperceptible and poorly understood factors of groundwater and temperature variations on the monuments in the Angkor World Heritage site (400 km2). We developed a two-scale synthetic aperture radar interferometry (InSAR) approach. We describe spatial-temporal displacements (at millimeter-level accuracy), as measured by high-resolution TerraSAR/TanDEM-X satellite images, to provide a new solution to resolve the current controversy surrounding the potential structural collapse of monuments in Angkor. Multidisciplinary analysis in conjunction with a deterioration kinetics model offers new insights into the causes that trigger the potential decline of Angkor monuments. Our results show that pumping groundwater for residential and touristic establishments did not threaten the sustainability of monuments during 2011 to 2013; however, seasonal variations of the groundwater table and the thermodynamics of stone materials are factors that could trigger and/or aggravate the deterioration of monuments. These factors amplify known impacts of chemical weathering and biological alteration of temple materials. The InSAR solution reported in this study could have implications for monitoring and sustainable conservation of monuments in World Heritage sites elsewhere. PMID:28275729

  12. X-ray interferometry with transmissive beam combiners for ultra-high angular resolution astronomy

    CERN Document Server

    Skinner, G K; 10.1007/s10686-009-9175-4


    Interferometry provides one of the possible routes to ultra-high angular resolution for X-ray and gamma-ray astronomy. Sub-micro-arc-second angular resolution, necessary to achieve objectives such as imaging the regions around the event horizon of a super-massive black hole at the center of an active galaxy, can be achieved if beams from parts of the incoming wavefront separated by 100s of meters can be stably and accurately brought together at small angles. One way of achieving this is by using grazing incidence mirrors. We here investigate an alternative approach in which the beams are recombined by optical elements working in transmission. It is shown that the use of diffractive elements is a particularly attractive option. We report experimental results from a simple 2-beam interferometer using a low-cost commercially available profiled film as the diffractive elements. A rotationally symmetric filled (or mostly filled) aperture variant of such an interferometer, equivalent to an X-ray axicon, is shown to...

  13. Deformation of the Augustine Volcano, Alaska, 1992-2005, measured by ERS and ENVISAT SAR interferometry (United States)

    Lee, Chang-Wook; Lu, Zhong; Kwoun, Oh-Ig; Won, Joong-Sun


    The Augustine Volcano is a conical-shaped, active stratovolcano located on an island of the same name in Cook Inlet, about 290 km southwest of Anchorage, Alaska. Augustine has experienced seven significant explosive eruptions - in 1812, 1883, 1908, 1935, 1963, 1976, 1986, and in January 2006. To measure the ground surface deformation of the Augustine Volcano before the 2006 eruption, we applied satellite radar interferometry using Synthetic Aperture Radar (SAR) images from three descending and three ascending satellite tracks acquired by European Remote Sensing Satellite (ERS) 1 and 2 and the Environment Satellite (ENVISAT). Multiple interferograms were stacked to reduce artifacts caused by atmospheric conditions, and we used a singular value decomposition method to retrieve the temporal deformation history from several points on the island. Interferograms during 1992 and 2005 show a subsidence of about 1-3 cm/year, caused by the contraction of pyroclastic flow deposits from the 1986 eruption. Subsidence has decreased exponentially with time. Multiple interferograms between 1992 and 2005 show no significant inflation around the volcano before the 2006 eruption. The lack of a pre-eruption deformation signal suggests that the deformation signal from 1992 to August 2005 must have been very small and may have been obscured by atmospheric delay artifacts. 

  14. Application of Fractional Fourier Transform to Moving Target Indication via Along-Track Interferometry

    Directory of Open Access Journals (Sweden)

    Chiu Shen


    Full Text Available A relatively unknown yet powerful technique, the so-called fractional Fourier transform (FrFT, is applied to SAR along-track interferometry (SAR-ATI in order to estimate moving target parameters. By mapping a target's signal onto a fractional Fourier axis, the FrFT permits a constant-velocity target to be focused in the fractional Fourier domain thereby affording orders of magnitude improvement in SCR. Moving target velocity and position parameters are derived and expressed in terms of an optimum fractional angle and a measured fractional Fourier position , allowing a target to be accurately repositioned and its velocity components computed without actually forming an SAR image. The new estimation algorithm is compared with the matched filter bank approach, showing some of the advantages of the FrFT method. The proposed technique is applied to the data acquired by the two-aperture CV580 airborne radar system configured in its along-track mode. Results show that the method is effective in estimating target velocity and position parameters.

  15. X-ray Interferometry with Transmissive Beam Combiners for Ultra-High Angular Resolution Astronomy (United States)

    Skinner, G. K.; Krismanic, John F.


    Abstract Interferometry provides one of the possible routes to ultra-high angular resolution for X-ray and gamma-ray astronomy. Sub-micro-arc-second angular resolution, necessary to achieve objectives such as imaging the regions around the event horizon of a super-massive black hole at the center of an active galaxy, can be achieved if beams from parts of the incoming wavefront separated by 100s of meters can be stably and accurately brought together at small angles. One way of achieving this is by using grazing incidence mirrors. We here investigate an alternative approach in which the beams are recombined by optical elements working in transmission. It is shown that the use of diffractive elements is a particularly attractive option. We report experimental results from a simple 2-beam interferometer using a low-cost commercially available profiled film as the diffractive elements. A rotationally symmetric filled (or mostly filled) aperture variant of such an interferometer, equivalent to an X-ray axicon, is shown to offer a much wider bandpass than either a Phase Fresnel Lens (PFL) or a PFL with a refractive lens in an achromatic pair. Simulations of an example system are presented.

  16. Time Delay Interferometry with Moving Spacecraft Arrays

    CERN Document Server

    Tinto, M; Armstrong, J W; Tinto, Massimo; Estabrook, Frank B.; Armstrong, adn J.W.


    Space-borne interferometric gravitational wave detectors, sensitive in the low-frequency (millihertz) band, will fly in the next decade. In these detectors the spacecraft-to-spacecraft light-travel-times will necessarily be unequal, time-varying, and (due to aberration) have different time delays on up- and down-links. Reduction of data from moving interferometric laser arrays in solar orbit will in fact encounter non-symmetric up- and downlink light time differences that are about 100 times larger than has previously been recognized. The time-delay interferometry (TDI) technique uses knowledge of these delays to cancel the otherwise dominant laser phase noise and yields a variety of data combinations sensitive to gravitational waves. Under the assumption that the (different) up- and downlink time delays are constant, we derive the TDI expressions for those combinations that rely only on four inter-spacecraft phase measurements. We then turn to the general problem that encompasses time-dependence of the light...

  17. General Relativistic Effects in Atom Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Dimopoulos, Savas; /Stanford U., Phys. Dept.; Graham, Peter W.; /SLAC /Stanford U., Phys. Dept.; Hogan, Jason M.; Kasevich, Mark A.; /Stanford U., Phys. Dept.


    Atom interferometry is now reaching sufficient precision to motivate laboratory tests of general relativity. We begin by explaining the non-relativistic calculation of the phase shift in an atom interferometer and deriving its range of validity. From this we develop a method for calculating the phase shift in general relativity. This formalism is then used to find the relativistic effects in an atom interferometer in a weak gravitational field for application to laboratory tests of general relativity. The potentially testable relativistic effects include the non-linear three-graviton coupling, the gravity of kinetic energy, and the falling of light. We propose experiments, one currently under construction, that could provide a test of the principle of equivalence to 1 part in 10{sup 15} (300 times better than the present limit), and general relativity at the 10% level, with many potential future improvements. We also consider applications to other metrics including the Lense-Thirring effect, the expansion of the universe, and preferred frame and location effects.

  18. Chameleon dark energy and atom interferometry (United States)

    Elder, Benjamin; Khoury, Justin; Haslinger, Philipp; Jaffe, Matt; Müller, Holger; Hamilton, Paul


    Atom interferometry experiments are searching for evidence of chameleon scalar fields with ever-increasing precision. As experiments become more precise, so too must theoretical predictions. Previous work has made numerous approximations to simplify the calculation, which in general requires solving a three-dimensional nonlinear partial differential equation. This paper calculates the chameleonic force using a numerical relaxation scheme on a uniform grid. This technique is more general than previous work, which assumed spherical symmetry to reduce the partial differential equation to a one-dimensional ordinary differential equation. We examine the effects of approximations made in previous efforts on this subject and calculate the chameleonic force in a setup that closely mimics the recent experiment of Hamilton et al. Specifically, we simulate the vacuum chamber as a cylinder with dimensions matching those of the experiment, taking into account the backreaction of the source mass, its offset from the center, and the effects of the chamber walls. Remarkably, the acceleration on a test atomic particle is found to differ by only 20% from the approximate analytical treatment. These results allow us to place rigorous constraints on the parameter space of chameleon field theories, although ultimately the constraint we find is the same as the one we reported in Hamilton et al. because we had slightly underestimated the size of the vacuum chamber. This computational technique will continue to be useful as experiments become even more precise and will also be a valuable tool in optimizing future searches for chameleon fields and related theories.

  19. 3D super-virtual refraction interferometry

    KAUST Repository

    Lu, Kai


    Super-virtual refraction interferometry enhances the signal-to-noise ratio of far-offset refractions. However, when applied to 3D cases, traditional 2D SVI suffers because the stationary positions of the source-receiver pairs might be any place along the recording plane, not just along a receiver line. Moreover, the effect of enhancing the SNR can be limited because of the limitations in the number of survey lines, irregular line geometries, and azimuthal range of arrivals. We have developed a 3D SVI method to overcome these problems. By integrating along the source or receiver lines, the cross-correlation or the convolution result of a trace pair with the source or receiver at the stationary position can be calculated without the requirement of knowing the stationary locations. In addition, the amplitudes of the cross-correlation and convolution results are largely strengthened by integration, which is helpful to further enhance the SNR. In this paper, both synthetic and field data examples are presented, demonstrating that the super-virtual refractions generated by our method have accurate traveltimes and much improved SNR.

  20. Quasar Astrophysics with the Space Interferometry Mission (United States)

    Unwin, Stephen; Wehrle, Ann; Meier, David; Jones, Dayton; Piner, Glenn


    Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V = 19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.