WorldWideScience

Sample records for subarcsecond resolution interferometric

  1. High-resolution diffraction grating interferometric transducer of linear displacements

    Science.gov (United States)

    Shang, Ping; Xia, Haojie; Fei, Yetai

    2016-01-01

    A high-resolution transducer of linear displacements is presented. The system is based on semiconductor laser illumination and a diffraction grating applied as a length master. The theory of the optical method is formulated using Doppler description. The relationship model among the interference strips, measurement errors, grating deflection around the X, Y and Z axes and translation along the Z axis is built. The grating interference strips' direction and space is not changed with movement along the X (direction of grating movement), Y (direction of grating line), Z axis, and the direction and space has a great effect when rotating around the X axis. Moreover the space is little affected by deflection around the Z axis however the direction is changed dramatically. In addition, the strips' position shifted rightward or downwards respectively for deflection around the X or Y axis. Because the emitted beams are separated on the grating plane, the tilt around the X axis error of the stage during motion will lead to the optical path difference of the two beams resulting in phase shift. This study investigates the influence of the tilt around the X axis error. Experiments show that after yaw error compensation, the high-resolution diffraction grating interferometric transducer readings can be significantly improved. The error can be reduced from +/-80 nm to +/-30 nm in maximum.

  2. A substellar-mass protostar and its outflow of IRAS 15398–3359 revealed by subarcsecond-resolution observations of H{sub 2}CO and CCH

    Energy Technology Data Exchange (ETDEWEB)

    Oya, Yoko; Sakai, Nami; Watanabe, Yoshimasa; Yamamoto, Satoshi [Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Sakai, Takeshi [Department of Communication Engineering and Informatics, Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofugaoka, Chofu, Tokyo 182-8585 (Japan); Hirota, Tomoya [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan); Lindberg, Johan E.; Bisschop, Suzanne E.; Jørgensen, Jes K. [Center for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Østeer Voldgade 5-7, DK-1350 Copenhagen K. (Denmark); Van Dishoeck, Ewine F., E-mail: nami@taurus.phys.s.u-tokyo.ac.jp [Leiden Observatory, Leiden University, P.O. Box 9513, 2300-RA Leiden, The Netherland (Netherlands)

    2014-11-10

    Subarcsecond (0.''5) images of H{sub 2}CO and CCH line emission have been obtained in the 0.8 mm band toward the low-mass protostar IRAS 15398–3359 in the Lupus 1 cloud as one of the Cycle 0 projects of the Atacama Large Millimeter/Submillimeter Array. We have detected a compact component concentrated in the vicinity of the protostar and a well-collimated outflow cavity extending along the northeast-southwest axis. The inclination angle of the outflow is found to be about 20°, or almost edge-on, based on the kinematic structure of the outflow cavity. This is in contrast to previous suggestions of a more pole-on geometry. The centrally concentrated component is interpreted by use of a model of the infalling rotating envelope with the estimated inclination angle and the mass of the protostar is estimated to be less than 0.09 M {sub ☉}. Higher spatial resolution data are needed to infer the presence of a rotationally supported disk for this source, hinted at by a weak high-velocity H{sub 2}CO emission associated with the protostar.

  3. Interferometric microwave radiometers for high-resolution imaging of the atmosphere brightness temperature based on the adaptive Capon signal processing algorithm.

    Science.gov (United States)

    Park, Hyuk; Choi, Junho; Katkovnik, Vladimir; Kim, Yonghoon

    2004-03-01

    Passive microwave remote sensing from satellites and ground stations has contributed uniquely, and substantially, to the study of atmospheric chemistry, meteorology, and environmental monitoring. As user requirements are raised, in terms of the accuracy and the spatial resolution, a mechanically scanning radiometer, with a real aperture, becomes impractical due to the requirement for a very large antenna size. However, an aperture synthesis interferometric radiometer presents a valuable alternative. The work presented in this paper was devoted to high spatial resolution imaging, using the 37 GHz band interferometric radiometer, developed by ourselves. The spatially adaptive Capon beamforming method was exploited for the imaging, which outperformed the conventional Fourier Transform method. We concluded that the high spatial resolution imaging of the brightness temperature of the atmosphere could be accomplished with an interferometric radiometer equipped with the developed Capon beamforming imaging algorithm.

  4. A frequency domain radar interferometric imaging (FII) technique based on high-resolution methods

    Science.gov (United States)

    Luce, H.; Yamamoto, M.; Fukao, S.; Helal, D.; Crochet, M.

    2001-01-01

    In the present work, we propose a frequency-domain interferometric imaging (FII) technique for a better knowledge of the vertical distribution of the atmospheric scatterers detected by MST radars. This is an extension of the dual frequency-domain interferometry (FDI) technique to multiple frequencies. Its objective is to reduce the ambiguity (resulting from the use of only two adjacent frequencies), inherent with the FDI technique. Different methods, commonly used in antenna array processing, are first described within the context of application to the FII technique. These methods are the Fourier-based imaging, the Capon's and the singular value decomposition method used with the MUSIC algorithm. Some preliminary simulations and tests performed on data collected with the middle and upper atmosphere (MU) radar (Shigaraki, Japan) are also presented. This work is a first step in the developments of the FII technique which seems to be very promising.

  5. Observing the Sun with the Atacama Large Millimeter/submillimeter Array (ALMA): High-Resolution Interferometric Imaging

    Science.gov (United States)

    Shimojo, M.; Bastian, T. S.; Hales, A. S.; White, S. M.; Iwai, K.; Hills, R. E.; Hirota, A.; Phillips, N. M.; Sawada, T.; Yagoubov, P.; Siringo, G.; Asayama, S.; Sugimoto, M.; Brajša, R.; Skokić, I.; Bárta, M.; Kim, S.; de Gregorio-Monsalvo, I.; Corder, S. A.; Hudson, H. S.; Wedemeyer, S.; Gary, D. E.; De Pontieu, B.; Loukitcheva, M.; Fleishman, G. D.; Chen, B.; Kobelski, A.; Yan, Y.

    2017-07-01

    Observations of the Sun at millimeter and submillimeter wavelengths offer a unique probe into the structure, dynamics, and heating of the chromosphere; the structure of sunspots; the formation and eruption of prominences and filaments; and energetic phenomena such as jets and flares. High-resolution observations of the Sun at millimeter and submillimeter wavelengths are challenging due to the intense, extended, low-contrast, and dynamic nature of emission from the quiet Sun, and the extremely intense and variable nature of emissions associated with energetic phenomena. The Atacama Large Millimeter/submillimeter Array (ALMA) was designed with solar observations in mind. The requirements for solar observations are significantly different from observations of sidereal sources and special measures are necessary to successfully carry out this type of observations. We describe the commissioning efforts that enable the use of two frequency bands, the 3-mm band (Band 3) and the 1.25-mm band (Band 6), for continuum interferometric-imaging observations of the Sun with ALMA. Examples of high-resolution synthesized images obtained using the newly commissioned modes during the solar-commissioning campaign held in December 2015 are presented. Although only 30 of the eventual 66 ALMA antennas were used for the campaign, the solar images synthesized from the ALMA commissioning data reveal new features of the solar atmosphere that demonstrate the potential power of ALMA solar observations. The ongoing expansion of ALMA and solar-commissioning efforts will continue to enable new and unique solar observing capabilities.

  6. High-resolution interferometric imaging of stress propagation in pediatric and adult skulls

    Science.gov (United States)

    Conerty, Michelle D.; Castracane, James; Clow, Lawrence P., Jr.; Koltai, Peter J.; Mouzakes, Jason

    1997-05-01

    Variations based on bone growth and development make stress and fracture propagation differ greatly in pediatric skulls as compared to adult skulls. Differentiating the stress propagation between the pediatric and adult skulls can improve diagnostic prediction when presented with direct frontal impact on a pediatric skull, a fairly common occurrence in the clinical environment. Critical diagnostic information can be learned from an in depth study of stress propagation as a function of impact force at critical locations on the periorbital region of the human skull. The Division of Pediatric Otolaryngology at Albany Medical College and InterScience, Inc. are utilizing electronic speckle pattern interferometry detection (ESPI) and high resolution imaging to evaluate and compare stress propagation in pediatric and adult skulls. A dual detection ESPI system was developed which integrates a medium resolution (2/3') CCD capable of real-time image processing, with a high resolution, megapixel detector capable of limited real time acquisition and image processing in software. Options to allow for high speed detection include integrating a custom, high performance image intensifier with the megapixel detector leg to be used as a high speed gate. The dual optical layout will allow for continuous and pulsed ESPI evaluation of calibrated impacts at specific landmarks on the skull. The goal of this work is to produce a full quantitative analysis of the stress propagation in pediatric versus adult skulls for a better understanding of bone dynamics. The work presented below concentrates on the development of the dual detection ESPI system and initial results achieved with an adult cadaver skull.

  7. Non-interferometric deep optical resolution photoacoustic remote sensing microscopy (Conference Presentation)

    Science.gov (United States)

    HajiReza, Parsin H.; Bell, Kevan L.; Shi, Wei; Zemp, Roger J.

    2017-03-01

    A novel all-optical non-contact photoacoustic microscopy system is introduced. The confocal configuration is used to ensure detection of initial pressure shock wave-induced intensity reflections at the subsurface origin where pressures are largest. Phantom studies confirm signal dependence on optical absorption, index-contrast, and excitation fluence. Taking advantage of a focused1310 nm interrogation beam, the penetration depth of the system is improved to 2mm for an optical resolution system. High signal-to-noise ratios (>60dB) with 2.5 cm working distance from the objective lens to the sample is achieved. Real-time in-vivo imaging of microvasculature and melanoma tumors are demonstrated.

  8. SPAM: A data reduction recipe for high-resolution,low-frequency radio-interferometric observations

    Science.gov (United States)

    Intema, H. T.

    High-resolution astronomical imaging at sub-GHz radio frequencies has been available for more than 15 years, with the VLA at 74 and 330 MHz, and the GMRT at 150, 240, 330 and 610 MHz. Recent developments include wide-bandwidth upgrades for VLA and GMRT, and commissioning of the aperture-array-based, multibeam telescope LOFAR. A common feature of these telescopes is the necessity to deconvolve the very many detectable sources within their wide fields-of-view and beyond. This is complicated by gain variations in the radio signal path that depend on viewing direction. One such example is phase errors due to the ionosphere. Here I discuss the inner workings of SPAM, a set of AIPS-based data reduction scripts in Python that includes direction-dependent calibration and imaging. Since its first version in 2008, SPAM has been applied to many GMRT data sets at various frequencies. Many valuable lessons were learned, and translated into various SPAM software modifications. Nowadays, semi-automated SPAM data reduction recipes can be applied to almost any GMRT data set, yielding good quality continuum images comparable with (or often better than) hand-reduced results. SPAM is currently being migrated from AIPS to CASA with an extension to handle wide bandwidths. This is aimed at providing users of the VLA low-band system and the upcoming widebandwidth GMRT with the necessary data reduction tools.

  9. Subarcsecond imaging of the water emission in Arp 220

    Science.gov (United States)

    König, S.; Martín, S.; Muller, S.; Cernicharo, J.; Sakamoto, K.; Zschaechner, L. K.; Humphreys, E. M. L.; Mroczkowski, T.; Krips, M.; Galametz, M.; Aalto, S.; Vlemmings, W. H. T.; Ott, J.; Meier, D. S.; Fuente, A.; García-Burillo, S.; Neri, R.

    2017-06-01

    Aims: Extragalactic observations of water emission can provide valuable insight into the excitation of the interstellar medium. In particular they allow us to investigate the excitation mechanisms in obscured nuclei, that is, whether an active galactic nucleus or a starburst dominates. Methods: We use subarcsecond resolution observations to tackle the nature of the water emission in Arp 220. ALMA Band 5 science verification observations of the 183 GHz H2O 313 - 220 line, in conjunction with new ALMA Band 7 H2O 515 - 422 data at 325 GHz, and supplementary 22 GHz H2O 616 - 523 VLA observations, are used to better constrain the parameter space in the excitation modeling of the water lines. Results: We detect 183 GHz H2O and 325 GHz water emission toward the two compact nuclei at the center of Arp 220, being brighter in Arp 220 West. The emission at these two frequencies is compared to previous single-dish data and does not show evidence of variability. The 183 and 325 GHz lines show similar spectra and kinematics, but the 22 GHz profile is significantly different in both nuclei due to a blend with an NH3 absorption line. Conclusions: Our findings suggest that the most likely scenario to cause the observed water emission in Arp 220 is a large number of independent masers originating from numerous star-forming regions. Based on observations carried in ALMA programs ADS/JAO.ALMA#2011.0.00018.SV and ADS/JAO.ALMA#2012.1.00453.S, with the IRAM 30 m telescope under project numbers 189-12 and 186-13.We dedicate this work to the memory of Fred Lo.

  10. Sub-Arcsecond Sub-mm Continuum Observations of Orion-KL

    Energy Technology Data Exchange (ETDEWEB)

    Beuther, H

    2004-06-25

    We present the first 865 {micro}m continuum image with sub-arcsecond resolution obtained with the Submillimeter Array. These data resolve the Orion-KL region into the hot core, the nearby radio source I, the sub-mm counterpart to the infrared source n (radio source L), and new sub-mm continuum sources. The radio to submillimeter emission from source I may be modeled as either the result of proton-electron free-free emission that is optically thick to {approx} 100 GHz plus dust emission that accounts for the majority of the submillimeter flux, or H{sup -} free-free emission that gives rise to a power-law spectrum with power-law index of {approx} 1.6. The latter model would indicate similar physical conditions as found in the inner circumstellar environment of Mira variable stars. Future sub-arcsecond observations at shorter sub-mm wavelengths should easily discriminate between these two possibilities. The sub-mm continuum emission toward source n can be interpreted in the framework of emission from an accretion disk.

  11. Three-dimensional Super Resolution Microscopy of F-actin Filaments by Interferometric PhotoActivated Localization Microscopy (iPALM).

    Science.gov (United States)

    Wang, Yilin; Kanchanawong, Pakorn

    2016-12-01

    Fluorescence microscopy enables direct visualization of specific biomolecules within cells. However, for conventional fluorescence microscopy, the spatial resolution is restricted by diffraction to ~ 200 nm within the image plane and > 500 nm along the optical axis. As a result, fluorescence microscopy has long been severely limited in the observation of ultrastructural features within cells. The recent development of super resolution microscopy methods has overcome this limitation. In particular, the advent of photoswitchable fluorophores enables localization-based super resolution microscopy, which provides resolving power approaching the molecular-length scale. Here, we describe the application of a three-dimensional super resolution microscopy method based on single-molecule localization microscopy and multiphase interferometry, called interferometric PhotoActivated Localization Microscopy (iPALM). This method provides nearly isotropic resolution on the order of 20 nm in all three dimensions. Protocols for visualizing the filamentous actin cytoskeleton, including specimen preparation and operation of the iPALM instrument, are described here. These protocols are also readily adaptable and instructive for the study of other ultrastructural features in cells.

  12. Interferometric filters for spectral discrimination in high-spectral-resolution lidar: performance comparisons between Fabry-Perot interferometer and field-widened Michelson interferometer.

    Science.gov (United States)

    Cheng, Zhongtao; Liu, Dong; Yang, Yongying; Yang, Liming; Huang, Hanlu

    2013-11-10

    Thanks to wavelength flexibility, interferometric filters such as Fabry-Perot interferometers (FPIs) and field-widened Michelson interferometers (FWMIs) have shown great convenience for spectrally separating the molecule and aerosol scattering components in the high-spectral-resolution lidar (HSRL) return signal. In this paper, performance comparisons between the FPI and FWMI as a spectroscopic discrimination filter in HSRL are performed. We first present a theoretical method for spectral transmission analysis and quantitative evaluation on the spectral discrimination. Then the process in determining the parameters of the FPI and FWMI for the performance comparisons is described. The influences from the incident field of view (FOV), the cumulative wavefront error induced by practical imperfections, and the frequency locking error on the spectral discrimination performance of the two filters are discussed in detail. Quantitative analyses demonstrate that FPI can produce higher transmittance while the remarkable spectral discrimination is one of the most appealing advantages of FWMI. As a result of the field-widened design, the FWMI still performs well even under the illumination with large FOV while the FPI is only qualified for a small incident angle. The cumulative wavefront error attaches a great effect on the spectral discrimination performance of the interferometric filters. We suggest if a cumulative wavefront error is less than 0.05 waves RMS, it is beneficial to employ the FWMI; otherwise, FPI may be more proper. Although the FWMI shows much more sensitivity to the frequency locking error, it can outperform the FPI given a locking error less than 0.1 GHz is achieved. In summary, the FWMI is very competent in HSRL applications if these practical engineering and control problems can be solved, theoretically. Some other estimations neglected in this paper can also be carried out through the analytical method illustrated herein.

  13. Probing Gas and Dust around B[e] Stars at the Highest Angular Resolution: A Decade of Interferometric Studies

    Science.gov (United States)

    Meilland, A.

    2017-02-01

    Long-baseline interferometry is the one and only technique offering the sub-milliarcsecond resolution needed to spatially resolve the close environment of stars. Since the construction of modern facilities such as the Very Large Telescope Interferometer (VLTI) in Chile, and the Center for High Resolution Array (CHARA) in California, it became a key technique to probe massive stars and their often complex circumstellar environments. The more recent generation of instruments even combines the power of interferometry and spectroscopy allowing to put more constraints on chemical, physical, and dynamical properties of circumstellar gas and dust. Here I briefly present the technique and the current generation of instruments, I review the main results obtained in the last decade on B[e] stars, and, I present the upcoming second generation of instruments at VLTI and the current plan to upgrade CHARA.

  14. New-Generation Interferometric Polarimetry

    Science.gov (United States)

    Marti-Vidal, Ivan

    2017-10-01

    Polarized emission encodes essential information for very different fields of Astrophysics: from the study of dust grains and magnetic fields in proto-planetary discs and evolved stars, to the formation and propagation of relativistic outflows in Active Galactic Nuclei, or the study of inflation and primordial gravitational waves from the CMB anisotropies. Observing polarized light at very high angular resolutions and sensitivities typically involves the use of interferometric techniques. New-generation interferometric instruments, which cover new windows to the Universe with wide fractional bandwidths, are pushing the polarimetric observational capabilities to the technical limits. In this talk, we will summarize the techniques of interferometric polarimetry, focusing on the problem of data calibration and interpretation, and will discuss novel algorithms developed for the new-generation interferometers, which are already starting to produce ground-breaking results in Astrophysics.

  15. Interferometric star tracker Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Optical Physics Company (OPC) proposes to develop a high accuracy version of its interferometric star tracker capable of meeting the milli-arcsecond-level pointing...

  16. CLUSTERED RADIO INTERFEROMETRIC CALIBRATION

    NARCIS (Netherlands)

    Kazemi, S.; Yatawatta, S.; Zaroubi, S.

    2011-01-01

    This paper introduces an amendment to radio interferometric calibration of sources below the noise level. The main idea is to employ the information of the stronger sources' measured signals as a plug-in criterion to solve for the weaker ones. For this purpose, we construct a number of source

  17. Interferometric Creep Testing.

    Science.gov (United States)

    1985-03-01

    Wolff and R. C. Savedra, "Precision Interferometric Dilatometer ," submitted to Rev. Sci. Instrum. *U.S.GPO: .1,35 41 , .. , , .. ., , ...4 . ...I...analysis; effects of solar activity, magnetic storms and nuclear explosions on the earth’s atmosphere, Ionosphere and magnetosphere; effects of

  18. Self Calibrating Interferometric Sensor

    DEFF Research Database (Denmark)

    Sørensen, Henrik Schiøtt

    This thesis deals with the development of an optical sensor based on micro interferometric backscatter detection (MIBD). A price effective, highly sensitive and ready for mass production platform is the goal of this project. The thesis covers three areas. The first part of the thesis deals...

  19. Subarcsecond resolution observations of warm water towards three deeply embedded low-mass protostars

    DEFF Research Database (Denmark)

    Persson, Magnus Vilhelm; Jørgensen, Jes Kristian; van Dishoeck, Ewine F.

    2012-01-01

    Water is present during all stages of star formation: as ice in the cold outer parts of protostellar envelopes and dense inner regions of circumstellar disks, and as gas in the envelopes close to the protostars, in the upper layers of circumstellar disks and in regions of powerful outflows and sh...

  20. Automation of interferometric observations

    Science.gov (United States)

    Bester, M.; Degiacomi, C. G.; Danchi, W. C.; Greenhill, L. J.; Townes, C. H.

    The Infrared Spatial Interferometer (ISI) is a heterodyne interferometer that operates in the 9-12 micron atmospheric window. It is located at Mount Wilson and consists of two 1.65-m Pfund-type telescopes. Presently baselines range up to 35 m. Lately the performance of the ISI was improved significantly, providing higher quality interferometric data. The improvements include all-reflective front-end optics, larger bandwidth and higher quantum efficiency heterodyne detectors, a fringe calibration system, a CCD autoguiding system, and a more advanced computer control system. The newly developed control software allows the observations to be largely automated.

  1. Evanescent interferometric lithography.

    Science.gov (United States)

    Blaikie, R J; McNab, S J

    2001-04-01

    Simulation results are presented to illustrate the main features of what we believe is a new photolithographic technique, evanescent interferometric lithography (EIL). The technique exploits interference between resonantly enhanced, evanescently decaying diffracted orders to create a frequency-doubled intensity pattern in the near field of a metallic diffraction grating. It is shown that the intensity in a grating's near field can be enhanced significantly compared with conventional interferometric lithography. Contrast in the interference pattern is also increased, owing to a reduction in the zeroth-order transmission near resonance. The pattern's depth of field reduces as the wavelength is increased beyond cutoff of the first-order diffracted components, and results are presented showing the trade-offs that can be made between depth of field and intensity enhancement. Examples are given for a 270-nm-period grating embedded in material with refractive index n = 1.6 and illuminated with wavelengths near 450 nm. Under these conditions it is predicted that high-intensity, high-contrast patterns with 135-nm period can be formed in photoresists more than 50 nm thick.

  2. Interferometric fiber optic sensors.

    Science.gov (United States)

    Lee, Byeong Ha; Kim, Young Ho; Park, Kwan Seob; Eom, Joo Beom; Kim, Myoung Jin; Rho, Byung Sup; Choi, Hae Young

    2012-01-01

    Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG) is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair.

  3. Interferometric Fiber Optic Sensors

    Directory of Open Access Journals (Sweden)

    Hae Young Choi

    2012-02-01

    Full Text Available Fiber optic interferometers to sense various physical parameters including temperature, strain, pressure, and refractive index have been widely investigated. They can be categorized into four types: Fabry-Perot, Mach-Zehnder, Michelson, and Sagnac. In this paper, each type of interferometric sensor is reviewed in terms of operating principles, fabrication methods, and application fields. Some specific examples of recently reported interferometeric sensor technologies are presented in detail to show their large potential in practical applications. Some of the simple to fabricate but exceedingly effective Fabry-Perot interferometers, implemented in both extrinsic and intrinsic structures, are discussed. Also, a wide variety of Mach-Zehnder and Michelson interferometric sensors based on photonic crystal fibers are introduced along with their remarkable sensing performances. Finally, the simultaneous multi-parameter sensing capability of a pair of long period fiber grating (LPG is presented in two types of structures; one is the Mach-Zehnder interferometer formed in a double cladding fiber and the other is the highly sensitive Sagnac interferometer cascaded with an LPG pair.

  4. Coherent interferometric imaging, time gating and beamforming

    Science.gov (United States)

    Borcea, Liliana; Garnier, Josselin; Papanicolaou, George; Tsogka, Chrysoula

    2011-06-01

    Coherent interferometric imaging is based on the backpropagation of local spacetime cross-correlations of array data and was introduced in order to improve images when the medium between the array and the object to be imaged is inhomogeneous and unknown (Borcea et al 2005 Inverse Problems 21 1419). Although this method has been shown to be effective and is well founded theoretically, the coherent interferometric imaging function is computationally expensive and therefore difficult to use. In this paper, we show that this function is equivalent to a windowed beamformer energy function, that is, a quadratic function that involves only time gating and time delaying signals in emission and in reception. In this form the coherent interferometric imaging can be implemented efficiently both in hardware and software, that is, at a computational cost that is comparable to the usual beamforming and migration imaging methods. We also revisit the trade-off between enhanced image stability and loss of resolution in coherent interferometry from the point of view of its equivalence to a windowed beamformer energy imaging function.

  5. Optical cements for interferometric applications

    OpenAIRE

    Wimperis, J.R.; Johnston, Sean F.

    1984-01-01

    The wave front distortion introduced by optical cements\\ud is important in interferometric applications. We describe\\ud here tests performed to characterize two common cements,\\ud Epo-Tek 301 and Norland Optical Adhesive 61.

  6. An optical fibre interferometric refractometer

    OpenAIRE

    Suhadolnik, Alojz

    2015-01-01

    A new type of optical fibre interferometric refractometer has been made. A double interferometer consists of an optical fibre Mach-Zehnder interferometerand a Michelson interferometer. The first one measures the optical path length difference of the moving sample, while the second one measures the liquid sample displacement in air. A fringe count technique was used on both interferometers in order to obtain the refractive indices of different liquids. The described optical fibre interferometr...

  7. The FLUOR interferometric beam combiner

    Science.gov (United States)

    Coudé du Foresto, Vincent; Chagnon, Gilles; Lacasse, Marc; Mennesson, Bertrand; Morel, Sébastien; Perrin, Guy; Ridgway, Steve; Traub, Wesley

    2001-01-01

    FLUOR stands for Fibered Linked Unit for Optical Recombination and is an interferometric instrument which started out as a technology demonstrator, demonstrated the potential of single-mode fiber optics for high precision visibility measurements, and has been operated as a focal instrument of the IOTA interferometer since 1995. After a presentation of the instrument, the programs carried out with FLUOR are reviewed, as well as the perspectives introduced by interferometric observations with a high dynamic range.

  8. Interferometric radar measurements

    Science.gov (United States)

    Smith, Ronald A.; Shipman, Mark; Holder, E. J.; Williams, James K.

    2002-08-01

    The United States Army Space and Missile Defense Command (USASMDC) has interest in a technology demonstration that capitalizes on investment in fire control and smart interceptor technologies that have matured beyond basic research. The concept SWORD (Short range missile defense With Optimized Radar Distribution) consists of a novel approach utilizing a missile interceptor and interferometric fire control radar. A hit-to-kill, closed-loop, command guidance scheme is planned that takes advantage of extremely accurate target and interceptor state vectors derived via the fire control radar. The fire control system has the capability to detect, track, and classify multiple threats in a tactical regime as well as simultaneously provide command guidance updates to multiple missile interceptors. The missile interceptor offers a cost reduction potential as well as an enhancement to the kinematics range and lethality over existing SHORAD systems. Additionally, the Radio Frequency (RF) guidance scheme offers increased battlefield weather performance. The Air Defense (AD) community, responding to current threat capabilities and trends, has identified an urgent need to have a capability to counter proliferated, low cost threats with a low cost-per-kill weapon system. The SWORD system will offer a solution that meets this need. The SWORD critical technologies will be identified including a detailed description of each. Validated test results and basic principles of operation will be presented to prove the merit of past investments. The Deputy Assistant Secretary of the Army for Research and Technology (DAS(R&T) has a three- year Science and Technology Program to evaluate the errors and proposed mitigation techniques associated with target spectral dispersion and range gate straddle. Preliminary bench-top experiment results will be presented in this paper.

  9. VCSELs for interferometric readout of MEMS sensors

    Science.gov (United States)

    Serkland, Darwin K.; Geib, Kent M.; Peake, Gregory M.; Keeler, Gordon A.; Shaw, Michael J.; Baker, Michael S.; Okandan, Murat

    2016-03-01

    We report on the development of single-frequency VCSELs (vertical-cavity surface-emitting lasers) for sensing the position of a moving MEMS (micro-electro-mechanical system) object with resolution much less than 1nm. Position measurement is the basis of many different types of MEMS sensors, including accelerometers, gyroscopes, and pressure sensors. Typically, by switching from a traditional capacitive electronic readout to an interferometric optical readout, the resolution can be improved by an order of magnitude with a corresponding improvement in MEMS sensor performance. Because the VCSEL wavelength determines the scale of the position measurement, laser wavelength (frequency) stability is desirable. This paper discusses the impact of VCSEL amplitude and frequency noise on the position measurement.

  10. MEMS Gyroscope with Interferometric Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is a novel MEMS gyroscope that uses micro-interferometric detection to measure the motion of the proof mass. Using an interferometric...

  11. Interferometric redatuming by sparse inversion

    NARCIS (Netherlands)

    Van der Neut, J.; Herrmann, F.J.

    2012-01-01

    Assuming that transmission responses are known between the surface and a particular depth level in the subsurface, seismic sources can be effectively mapped to this level by a process called interferometric redatuming. After redatuming, the obtained wavefields can be used for imaging below this

  12. Quantum interferometric measurements of temperature

    Science.gov (United States)

    Jarzyna, Marcin; Zwierz, Marcin

    2015-09-01

    We provide a detailed description of the quantum interferometric thermometer, which is a device that estimates the temperature of a sample from the measurements of the optical phase. We rigorously analyze the operation of such a device by studying the interaction of the optical probe system prepared in a single-mode Gaussian state with a heated sample modeled as a dissipative thermal reservoir. We find that this approach to thermometry is capable of measuring the temperature of a sample in the nanokelvin regime. Furthermore, we compare the fundamental precision of quantum interferometric thermometers with the theoretical precision offered by the classical idealized pyrometers, which infer the temperature from a measurement of the total thermal radiation emitted by the sample. We find that the interferometric thermometer provides a superior performance in temperature sensing even when compared with this idealized pyrometer. We predict that interferometric thermometers will prove useful for ultraprecise temperature sensing and stabilization of quantum optical experiments based on the nonlinear crystals and atomic vapors.

  13. Matched filtering with interferometric 21 cm experiments

    Science.gov (United States)

    White, Martin; Padmanabhan, Nikhil

    2017-10-01

    A new generation of interferometric instruments is emerging, which aims to use intensity mapping of redshifted 21 cm radiation to measure the large-scale structure of the Universe at z ≃ 1-2 over wide areas of the sky. While these instruments typically have limited angular resolution, they cover huge volumes and thus can be used to provide large samples of rare objects. In this paper we study how well such instruments could find spatially extended large-scale structures, such as cosmic voids, using a matched filter formalism. Such a formalism allows us to work in Fourier space, the natural space for interferometers, and to study the impact of finite u - v coverage, noise and foregrounds on our ability to recover voids. We find that in the absence of foregrounds, such instruments would provide enormous catalogs of voids, with high completeness, but that control of foregrounds is key to realizing this goal.

  14. The VAULT2.0 Observing Campaign: A Comprehensive Investigation of the Chromosphere-Corona Interface at Sub-arcsecond scales

    Science.gov (United States)

    Vourlidas, A.; Korendyke, C.; Tun-Beltran, S. D.; Ugarte-Urra, I.; Morrill, J. S.; Warren, H. P.; Young, P.; De Pontieu, B.; Gauzzi, G.; Reardon, K.

    2014-12-01

    We report the first results from an observing campaign in support of the VAULT2.0 sounding rocket launch on September 30, 2014. VAULT2.0 is a Lya (1216Å) spectroheliograph capable of 0.3" (~250 km) spatial resolution. The objective of the VAULT2.0 project is the study of the chromosphere-corona interface. This interface has acquired renewed emphasis over the last few years, thanks to high-resolution observations from Hinode/SOT and EIS instruments and the Lya imaging from the two VAULT flights. The observations have shown that the upper chromosphere may play a more important role in heating the corona and in affecting EUV observations that previously thought: (1) by supplying the mass via Type-II spicules and, (2) by absorbing coronal emission. Many of the required clues for further progress are located in sub-arcsecond structures with temperatures between 10000 and 50000 K, a regime not accessible by Hinode or SDO. Lyman-alpha observations are, therefore, ideal, for filling in this gap. The observing campaign in support of the VAULT2.0 is closely coordinated with the Hinode and IRIS missions to study the mass/energy flow from the chromosphere to the corona with joint observations of type-II spicules, and the magnetic connectivity of coronal loops using the full imaging and spectral capabilities of IRIS, Hinode and SDO. Several ground-based observatories also provide important observations (IBIS, BBSO, SOLIS). The VAULT2.0 project is funded by the NASA LCAS program.

  15. An optical fibre interferometric refractometer

    Science.gov (United States)

    Suhadolnik, A.

    2007-05-01

    A new type of optical fibre interferometric refractometer has been made. A double interferometer consists of an optical fibre Mach-Zehnder interferometer and a Michelson interferometer. The first one measures the optical path length difference of the moving sample, while the second one measures the liquid sample displacement in air. A fringe count technique was used on both interferometers in order to obtain the refractive indices of different liquids. The described optical fibre interferometric refractometer was tested by measuring the refractive indices of different liquids, and the achieved results were compared to the results found in the literature. In addition, the refractive index of different concentrations of NaCl in water was measured and compared with the calculated calibration curve. The advantage of the proposed refractometer is high accuracy measurements including the simple construction of the optical fibre Mach-Zehnder interferometer and the commercially available Michelson interferometer.

  16. Robust sparse image reconstruction of radio interferometric observations with PURIFY

    Science.gov (United States)

    Pratley, Luke; McEwen, Jason D.; d'Avezac, Mayeul; Carrillo, Rafael E.; Onose, Alexandru; Wiaux, Yves

    2018-01-01

    Next-generation radio interferometers, such as the Square Kilometre Array, will revolutionize our understanding of the Universe through their unprecedented sensitivity and resolution. However, to realize these goals significant challenges in image and data processing need to be overcome. The standard methods in radio interferometry for reconstructing images, such as CLEAN, have served the community well over the last few decades and have survived largely because they are pragmatic. However, they produce reconstructed interferometric images that are limited in quality and scalability for big data. In this work, we apply and evaluate alternative interferometric reconstruction methods that make use of state-of-the-art sparse image reconstruction algorithms motivated by compressive sensing, which have been implemented in the PURIFY software package. In particular, we implement and apply the proximal alternating direction method of multipliers algorithm presented in a recent article. First, we assess the impact of the interpolation kernel used to perform gridding and degridding on sparse image reconstruction. We find that the Kaiser-Bessel interpolation kernel performs as well as prolate spheroidal wave functions while providing a computational saving and an analytic form. Secondly, we apply PURIFY to real interferometric observations from the Very Large Array and the Australia Telescope Compact Array and find that images recovered by PURIFY are of higher quality than those recovered by CLEAN. Thirdly, we discuss how PURIFY reconstructions exhibit additional advantages over those recovered by CLEAN. The latest version of PURIFY, with developments presented in this work, is made publicly available.

  17. Interferometric and optical tests of water window imaging x ray microscopes

    Science.gov (United States)

    Johnson, R. Barry

    1993-01-01

    Interferometric tests of Schwarzchild X-ray Microscope are performed to evaluate the optical properties and alignment of the components. Photographic measurements of the spatial resolution, focal properties, and vignetting characteristics of the prototype Water Window Imaging X-ray Microscope are made and analyzed.

  18. Polarimetric and Interferometric SAR Calibration Verification Methods

    Science.gov (United States)

    Kim, Y.; Zyl, J van

    2001-01-01

    It is necessary to calibrate SAR data in order to use the data for science applications. When both polarimetric and interferometric data are collected simultaneously, these SAR data can be used for cross-calibration and verification.

  19. An Innovative Transponder-Based Interferometric Radar for Vibration Measurements

    Science.gov (United States)

    Coppi, F.; Cerutti, A.; Farina, P.; De Pasquale, G.; Novembrini, G.

    2010-05-01

    Ground-based radar interferometry has recently emerged as an innovative technology of remote sensing, able to accurately measure the static or dynamic displacement of several points of a structure. This technique in the last couple of years has been applied to different types of structures, such as bridges, towers and chimneys. This paper presents a prototype system developed by IDS, originally aimed at measuring the structural vibrations of helicopter rotor blades, based on an interferometric technique and constituted by combination of a radar sensor and a series of transponders installed on the target structure. The main advantages of this solution with respect to conventional interferometric radars, are related to the increased spatial resolution of the system, provided by the possibility to discriminate different transponders installed within the same resolution cell of the radar sensor, and to the reduction of the ambient noise (e.g. multi-path) on the radar measurement. The first feature allows the use of the microwave technology even on target areas with limited dimensions, such as industrial facilities, while the second aspect may extend the use of radar interferometric systems to complex scenarios, where multi-reflections are expected due to the presence of natural targets with high reflectivity to the radar signal. In the paper, the system and its major characteristics are first described; subsequently, application to the measurement of ambient vibration response of a lab set-up is summarized. Then the data acquired on a rotating mock-up are reported and analyzed to identify natural frequencies and mode shapes of the investigated structure.

  20. Interferometric study on birds' feathers.

    Science.gov (United States)

    De la Torre-Ibarra, Manuel H; Santoyo, Fernando Mendoza

    2013-05-01

    Optical techniques such as speckle pattern interferometry are well known in the nondestructive testing measurement community. They can be used, for instance, as a predictor of the mechanical behavior of a sample under study. However, in almost all circumstances, a mathematical model has to be applied in order to make sense of these measurements. This is a critical issue when an organic sample is studied, mainly due to its complex deformation response. A good example of this is observed in the birds' feathers. They have extraordinary mechanical and aerodynamic properties thanks to their stiffness and lightness. A couple of live birds are safely situated in front of an out-of-plane sensitive digital holographic interferometer (DHI), an optical system capable of recovering the optical phase in this type of nonrepeatable or unpredictable experiment. In order to recover the backscattering signal and its interferometric response, several images are recorded from different sections of the plumage. Displacement maps are obtained from what is, as far as is known, the first time that full field microdisplacement maps are presented over a hummingbird and a parakeet plumage.

  1. SUBARCSECOND ANALYSIS OF THE INFALLING–ROTATING ENVELOPE AROUND THE CLASS I PROTOSTAR IRAS 04365+2535

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Nami [The Institute of Physical and Chemical Research (RIKEN), 2-1, Hirosawa, Wako-shi, Saitama 351-0198 (Japan); Oya, Yoko; López-Sepulcre, Ana; Watanabe, Yoshimasa; Yamamoto, Satoshi [Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Sakai, Takeshi [Department of Communication Engineering and Informatics, Graduate School of Informatics and Engineering, The University of Electro-Communications, Chofugaoka, Chofu, Tokyo 182-8585 (Japan); Hirota, Tomoya [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan); Aikawa, Yuri [Center for Computational Science, University of Tsukuba, Tsukuba, Ibaraki 305-8577 (Japan); Ceccarelli, Cecilia; Lefloch, Bertrand; Kahane, Claudine [Universite de Grenoble Alpes, IPAG, F-38000 Grenoble (France); Caux, Emmanuel; Vastel, Charlotte [Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France)

    2016-04-01

    Subarcsecond images of the rotational line emission of CS and SO have been obtained toward the Class I protostar IRAS 04365+2535 in TMC-1A with ALMA. A compact component around the protostar is clearly detected in the CS and SO emission. The velocity structure of the compact component of CS reveals infalling–rotating motion conserving the angular momentum. It is well explained by a ballistic model of an infalling–rotating envelope with the radius of the centrifugal barrier (one-half of the centrifugal radius) of 50 au, although the distribution of the infalling gas is asymmetric around the protostar. The distribution of SO is mostly concentrated around the radius of the centrifugal barrier of the simple model. Thus, a drastic change in chemical composition of the gas infalling onto the protostar is found to occur at a 50 au scale probably due to accretion shocks, demonstrating that the infalling material is significantly processed before being delivered into the disk.

  2. Guide-star-based computational adaptive optics for broadband interferometric tomography

    Science.gov (United States)

    Adie, Steven G.; Shemonski, Nathan D.; Graf, Benedikt W.; Ahmad, Adeel; Scott Carney, P.; Boppart, Stephen A.

    2012-11-01

    We present a method for the numerical correction of optical aberrations based on indirect sensing of the scattered wavefront from point-like scatterers ("guide stars") within a three-dimensional broadband interferometric tomogram. This method enables the correction of high-order monochromatic and chromatic aberrations utilizing guide stars that are revealed after numerical compensation of defocus and low-order aberrations of the optical system. Guide-star-based aberration correction in a silicone phantom with sparse sub-resolution-sized scatterers demonstrates improvement of resolution and signal-to-noise ratio over a large isotome. Results in highly scattering muscle tissue showed improved resolution of fine structure over an extended volume. Guide-star-based computational adaptive optics expands upon the use of image metrics for numerically optimizing the aberration correction in broadband interferometric tomography, and is analogous to phase-conjugation and time-reversal methods for focusing in turbid media.

  3. Applications of interferometrically derived terrain slopes: Normalization of SAR backscatter and the interferometric correlation coefficient

    Science.gov (United States)

    Werner, Charles L.; Wegmueller, Urs; Small, David L.; Rosen, Paul A.

    1994-01-01

    Terrain slopes, which can be measured with Synthetic Aperture Radar (SAR) interferometry either from a height map or from the interferometric phase gradient, were used to calculate the local incidence angle and the correct pixel area. Both are required for correct thematic interpretation of SAR data. The interferometric correlation depends on the pixel area projected on a plane perpendicular to the look vector and requires correction for slope effects. Methods for normalization of the backscatter and interferometric correlation for ERS-1 SAR are presented.

  4. Physics of interferometric gravitational wave detectors

    Indian Academy of Sciences (India)

    The Caltech-MIT joint LIGO project is operating three long-baseline interferometers (one of 2 km and two of 4 km) in order to unambiguously measure the infinitesimal displacements of isolated test masses which convey the signature of gravitational waves from astrophysical sources. An interferometric gravitational wave ...

  5. Interferometrical techniques for the investigation of dynamic events

    Science.gov (United States)

    Pedrini, Giancarlo; Alexeenko, Igor; Osten, Wolfgang

    2013-06-01

    The availability of high resolution CCD and CMOS sensors together with the increasing computer capacity have enabled the development of different interferometrical techniques (speckle interferometry, digital holography, digital sherography) which are well suited for real time measurements. Two or more interferograms are recorded on a digital sensor at different times and the deformation of the object occurring between the exposures is calculated from the phase change. Since the process to investigate can be very fast we cannot use the well-known temporal phase shift method for the determination of the phase but we use a spatial carrier method which allows to determine that phase from one single hologram. We will show that this method can be used as well for shearography. Applications of digital holographic techniques for the investigation of vibrations, defect detection in mechanical structure and time resolved measurement of deformation of microelectromechanical systems (MEMS) are presented together with some investigation of mechanical structures by using digital shearography with spatial carrier.

  6. Calibration of a High Resolution Airborne 3-D SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Grinder-Pedersen, Jan; Madsen, S.N.

    1997-01-01

    The potential of across-track interferometric (XTI) synthetic aperture radar (SAR) for producing high resolution 3D imagery has been demonstrated by several airborne systems including EMISAR, the dual frequency, polarimetric, and interferometric SAR developed at the Dept. of Electromagnetic Systems...

  7. Millimeter-wave Interferometric Synthetic Aperture Radar Data Imaging Based on Terrain Surface Projection

    Directory of Open Access Journals (Sweden)

    Wei Shun-jun

    2015-02-01

    Full Text Available Millimeter-wave Interferometric Synthetic Aperture Radar (InSAR has smaller size, lower weight, and higher resolution compared with other bands. Thus, it has become a hot research topic. However, owing to its shorter wavelength, millimeter-wave InSAR data processing requires high-precision measurements of platform motion. For nonideal trajectories, traditional methods face difficulties in echo imaging and interferogram extraction. In addition, existing methods mainly produce SAR images based on plane projection. When the terrain changes abruptly, these methods may cause strong interferometric phase unwrapping and geometric distortion in SAR images. To overcome the abovementioned disadvantages of conventional methods in millimeter-wave InSAR imaging, an approach based on terrain surface projection is proposed. The echoes of different antennas are projected on the same terrain surface space for data imaging and interferogram extraction. In addition, the relation between terrain elevation and interferometric phase is derived. Simulations and experimental results verify the effectiveness of the proposed method; furthermore, the proposed approach improves the precision of interferometric phase extraction in complex motion conditions, while minimizing geometric distortion and phase wrapping in rough terrain, which is more conducive to terrain description and elevation inversion.

  8. Interferometric analysis of laser-driven cylindrically focusing shock waves in a thin liquid layer

    OpenAIRE

    David Veysset; Alexei A. Мaznev; Thomas Pezeril; Steven Kooi; Nelson, Keith A

    2016-01-01

    Shock waves in condensed matter are of great importance for many areas of science and technology ranging from inertially confined fusion to planetary science and medicine. In laboratory studies of shock waves, there is a need in developing diagnostic techniques capable of measuring parameters of materials under shock with high spatial resolution. Here, time-resolved interferometric imaging is used to study laser-driven focusing shock waves in a thin liquid layer in an all-optical experiment. ...

  9. Multi-epoch sub-arcsecond [Fe II] spectroimaging of the DG Tau outflows with NIFS - I. First data epoch

    Science.gov (United States)

    White, M. C.; McGregor, P. J.; Bicknell, G. V.; Salmeron, R.; Beck, T. L.

    2014-06-01

    Investigating the outflows emanating from young stellar objects (YSOs) on sub-arcsecond scales provides important clues to the nature of the underlying accretion-ejection process occurring near the central protostar. We have investigated the structures and kinematics of the outflows driven by the YSO DG Tauri, using the Near-infrared Integral Field Spectrograph (NIFS) on Gemini North. The blueshifted outflow shows two distinct components in [Fe II] 1.644 μm emission, which are separated using multicomponent line fitting. Jet parameters are calculated for the high-velocity component. A stationary recollimation shock is observed, in agreement with previous X-ray and far-ultraviolet observations. The presence of this shock indicates that the innermost streamlines of the high-velocity component are launched at a very small radius, 0.01-0.15 au, from the central star. The jet accelerates and expands downstream of the recollimation shock; the `acceleration' is likely a sign of velocity variations in the jet. No evidence of rotation is found, and we compare this non-detection to previous counterclaims. Moving jet knots, likely the result of the jet velocity variations, are observed. One of these knots moves more slowly than previously observed knots, and the knot ejection interval appears to be non-periodic. An intermediate-velocity component surrounds this central jet, and is interpreted as the result of a turbulent mixing layer along the jet boundaries generated by lateral entrainment of material by the high-velocity jet. Lateral entrainment requires the presence of a magnetic field of strength a few mG or less at hundreds of au above the disc surface, which is argued to be a reasonable proposition. In H2 1-0 S(1) 2.1218 μm emission, a wide-angle, intermediate-velocity blueshifted outflow is observed. Both outflows are consistent with being launched by a magnetocentrifugal disc wind, although an X-wind origin for the high-velocity jet cannot be ruled out. The

  10. Advanced interferometric gravitational-wave detectors

    CERN Document Server

    Saulson, Peter R

    2019-01-01

    Gravitational waves are one of the most exciting and promising emerging areas of physics and astrophysics today. The detection of gravitational waves will rank among the most significant physics discoveries of the 21st century.Advanced Interferometric Gravitational-Wave Detectors brings together many of the world's top experts to deliver an authoritative and in-depth treatment on current and future detectors. Volume I is devoted to the essentials of gravitational-wave detectors, presenting the physical principles behind large-scale precision interferometry, the physics of the underlying noise sources that limit interferometer sensitivity, and an explanation of the key enabling technologies that are used in the detectors. Volume II provides an in-depth look at the Advanced LIGO and Advanced Virgo interferometers that have just finished construction, as well as examining future interferometric detector concepts. This two-volume set will provide students and researchers the comprehensive background needed to und...

  11. Testing of PZT shifters for interferometric measurements

    Science.gov (United States)

    Schmit, Joanna; Piatkowski, Tadeusz

    1991-08-01

    Nowadays PZT shifters are widely used for interferometric measurements by phase shifting methods. The required accuracy of single step is very high. There for the methods of measuring metrological features of PZT shifters are described specificly intensity methods in Michelson and Sagnac interferometers and Lissajoux figures method 1-D and 2-D Fourier transform method (FTM) in Fizeau interferometer. The 1-D FTM is found most convenient for real time calibration in experimental setup.

  12. On quantum interferometric measurements of temperature

    OpenAIRE

    Jarzyna, Marcin; Zwierz, Marcin

    2014-01-01

    We provide a detailed description of the quantum interferometric thermometer, which is a device that estimates the temperature of a sample from the measurements of the optical phase. For the first time, we rigorously analyze the operation of such a device by studying the interaction of the optical probe system prepared in a single-mode Gaussian state with a heated sample modeled as a dissipative thermal reservoir. We find that this approach to thermometry is capable of measuring the temperatu...

  13. Cross-calibration of interferometric SAR data

    DEFF Research Database (Denmark)

    Dall, Jørgen

    2003-01-01

    Generation of digital elevation models from interferometric synthetic aperture radar (SAR) data is a well established technique. Achieving a high geometric fidelity calls for a calibration accounting for inaccurate navigation data and system parameters as well as system imperfections. Fully...... automated calibration techniques are preferable, especially for operational mapping. The author presents one such technique, called cross-calibration. Though developed for single-pass interferometry, it may be applicable to multi-pass interferometry, too. Cross-calibration requires stability during mapping...

  14. A Laser Interferometric Miniature Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Carr, Dustin W., PhD.; Baldwin, Patrick C.; Milburn, Howard; Robinson, David

    2011-09-12

    This is the second year of a Phase II Small Business Innovation Research (SBIR) contract geared towards the development of a new seismic sensor. Ground-based seismic monitoring systems have proven to be very capable in identifying nuclear tests, and can provide somewhat precise information on the location and yield of the explosive device. Making these measurements, however, currently requires very expensive and bulky seismometers that are difficult to deploy in places where they are most needed. A high performance, compact device can enable rapid deployment of large scale arrays, which can in turn be used to provide higher quality data during times of critical need. The use of a laser interferometer-based device has shown considerable promise, while also presenting significant challenges. The greatest strength of this optical readout technique is the ability to decouple the mechanical design from the transducer, thus enabling a miniaturized design that is not accessible with conventional sensing techniques. However, the nonlinearity in the optical response must be accounted for in the sensor output. Previously, we had proposed using a force-feedback approach to position the sensor at a point of maximum linearity. However, it can be shown that the combined nonlinearities of the optical response and the force-feedback curve necessarily results in a significant amount of unwanted noise at low frequencies. Having realized this, we have developed a new approach that eliminates force feedback, allowing the proof mass to move freely at all times. This takes advantage of some advanced optical spatial filtering that was developed at Symphony Acoustics for other types of sensors, and was recently adapted to this work. After processing the signals in real time, the digital output of the device is intrinsically linear, and the sensor can operate at any orientation with the same level of resolution, while instantly adapting to significant changes in orientation. Ultimately, we

  15. Onboard Interferometric SAR Processor for the Ka-Band Radar Interferometer (KaRIn)

    Science.gov (United States)

    Esteban-Fernandez, Daniel; Rodriquez, Ernesto; Peral, Eva; Clark, Duane I.; Wu, Xiaoqing

    2011-01-01

    An interferometric synthetic aperture radar (SAR) onboard processor concept and algorithm has been developed for the Ka-band radar interferometer (KaRIn) instrument on the Surface and Ocean Topography (SWOT) mission. This is a mission- critical subsystem that will perform interferometric SAR processing and multi-look averaging over the oceans to decrease the data rate by three orders of magnitude, and therefore enable the downlink of the radar data to the ground. The onboard processor performs demodulation, range compression, coregistration, and re-sampling, and forms nine azimuth squinted beams. For each of them, an interferogram is generated, including common-band spectral filtering to improve correlation, followed by averaging to the final 1 1-km ground resolution pixel. The onboard processor has been prototyped on a custom FPGA-based cPCI board, which will be part of the radar s digital subsystem. The level of complexity of this technology, dictated by the implementation of interferometric SAR processing at high resolution, the extremely tight level of accuracy required, and its implementation on FPGAs are unprecedented at the time of this reporting for an onboard processor for flight applications.

  16. High-temperature fiber-optic Fabry-Perot interferometric sensors.

    Science.gov (United States)

    Ding, Wenhui; Jiang, Yi; Gao, Ran; Liu, Yuewu

    2015-05-01

    A photonic crystal fiber (PCF) based high-temperature fiber-optic sensor is proposed and experimentally demonstrated. The sensor head is a Fabry-Perot cavity manufactured with a short section of endless single-mode photonic crystal fiber (ESM PCF). The interferometric spectrum of the Fabry-Perot interferometer is collected by a charge coupled device linear array based micro spectrometer. A high-resolution demodulation algorithm is used to interrogate the peak wavelengths. Experimental results show that the temperature range of 1200 °C and the temperature resolution of 1 °C are achieved.

  17. LIINUS/SERPIL: a design study for interferometric imaging spectroscopy at the LBT

    Science.gov (United States)

    Müller Sánchez, F.; Gál, C.; Eisenhauer, F.; Krabbe, A.; Haug, M.; Iserlohe, C.; Herbst, T. M.

    2008-07-01

    We present two design concepts and the science drivers of a proposed near-infrared interferometric integral field spectrograph for the LBT. This instrument will expand the capabilities of the currently-under-construction interferometric camera LINC-NIRVANA with spectroscopy by means of an integral field unit (IFU) located inside the LINC cryostat. Two instrument concepts have been studied in detail: a microlens array IFU with a spectrograph built entirely inside LINC (the LIINUS approach), and a lenslet+fibers IFU feeding an external spectrograph (the SERPIL approach). In both cases, the instrument incorporates imaging interferometry with integral field spectroscopy, an ideal combination for detailed studies of astronomical objects down to below 10mas angular resolution in the near-infrared. The scientific applications range from solar system studies and spectroscopy of exoplanets to the dynamics of stars and gas in the central regions of the Milky Way and other nearby galaxies.

  18. SAR Interferogram Filtering of Shearlet Domain Based on Interferometric Phase Statistics

    Directory of Open Access Journals (Sweden)

    Yonghong He

    2017-02-01

    Full Text Available This paper presents a new filtering approach for Synthetic Aperture Radar (SAR interferometric phase noise reduction in the shearlet domain, depending on the coherent statistical characteristics. Shearlets provide a multidirectional and multiscale decomposition that have advantages over wavelet filtering methods when dealing with noisy phase fringes. Phase noise in SAR interferograms is directly related to the interferometric coherence and the look number of the interferogram. Therefore, an optimal interferogram filter should incorporate information from both of them. The proposed method combines the phase noise standard deviation with the shearlet transform. Experimental results show that the proposed method can reduce the interferogram noise while maintaining the spatial resolution, especially in areas with low coherence.

  19. Interferometric Calibration with Natural Distributed Targets

    DEFF Research Database (Denmark)

    Dall, Jørgen; Christensen, Erik Lintz

    2002-01-01

    Cross-calibration is a fully automated algorithm for calibration of interferometric synthetic aperture radar (IFSAR) data. It has been developed for single-pass interferometry, but the principles may be applicable to multi-pass interferometry, too. The algorithm is based on natural distributed ta....... The algorithm appears to be fairly robust with respect to the terrain type. However, the result of the calibration may deteriorate if the terrain elevation, as measured with the SAR, changes systematically with the incidence angle or the aspect angle....

  20. Initial interferometric pre-investigations for LISA

    Energy Technology Data Exchange (ETDEWEB)

    Fitzsimons, E D; Bogenstahl, J; Hough, J; Killow, C; Perreur-Lloyd, M; Robertson, D I; Rowan, S; Ward, H, E-mail: e.fitzsimons@physics.gla.ac.u [Institute for Gravitational Research, Department of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

    2009-03-01

    LISA, the Laser Interferometer Space Antenna, is a proposed ESA/NASA space based gravitational wave detector. In order to help meet the many technological challenges of LISA, the ESA precursor mission LISA Pathfinder (LPF) will test some of the key enabling technologies for LISA. LPF however will only go so far, and much work is needed to take LPF technology to a state suitable for LISA. One such area is the use of polarising Mach-Zehnder interferometers. We report on the design and initial construction of an experiment to test the use of such interferometric techniques, as well as suitable component mounting mechanisms.

  1. Light-pulse atom interferometric device

    Science.gov (United States)

    Biedermann, Grant; McGuinness, Hayden James Evans; Rakholia, Akash; Jau, Yuan-Yu; Schwindt, Peter; Wheeler, David R.

    2016-03-22

    An atomic interferometric device useful, e.g., for measuring acceleration or rotation is provided. The device comprises at least one vapor cell containing a Raman-active chemical species, an optical system, and at least one detector. The optical system is conformed to implement a Raman pulse interferometer in which Raman transitions are stimulated in a warm vapor of the Raman-active chemical species. The detector is conformed to detect changes in the populations of different internal states of atoms that have been irradiated by the optical system.

  2. Probing interferometric parallax with interplanetary spacecraft

    Science.gov (United States)

    Rodeghiero, G.; Gini, F.; Marchili, N.; Jain, P.; Ralston, J. P.; Dallacasa, D.; Naletto, G.; Possenti, A.; Barbieri, C.; Franceschini, A.; Zampieri, L.

    2017-07-01

    We describe an experimental scenario for testing a novel method to measure distance and proper motion of astronomical sources. The method is based on multi-epoch observations of amplitude or intensity correlations between separate receiving systems. This technique is called Interferometric Parallax, and efficiently exploits phase information that has traditionally been overlooked. The test case we discuss combines amplitude correlations of signals from deep space interplanetary spacecraft with those from distant galactic and extragalactic radio sources with the goal of estimating the interplanetary spacecraft distance. Interferometric parallax relies on the detection of wavefront curvature effects in signals collected by pairs of separate receiving systems. The method shows promising potentialities over current techniques when the target is unresolved from the background reference sources. Developments in this field might lead to the construction of an independent, geometrical cosmic distance ladder using a dedicated project and future generation instruments. We present a conceptual overview supported by numerical estimates of its performances applied to a spacecraft orbiting the Solar System. Simulations support the feasibility of measurements with a simple and time-saving observational scheme using current facilities.

  3. Interferometric interpolation of sparse marine data

    KAUST Repository

    Hanafy, Sherif M.

    2013-10-11

    We present the theory and numerical results for interferometrically interpolating 2D and 3D marine surface seismic profiles data. For the interpolation of seismic data we use the combination of a recorded Green\\'s function and a model-based Green\\'s function for a water-layer model. Synthetic (2D and 3D) and field (2D) results show that the seismic data with sparse receiver intervals can be accurately interpolated to smaller intervals using multiples in the data. An up- and downgoing separation of both recorded and model-based Green\\'s functions can help in minimizing artefacts in a virtual shot gather. If the up- and downgoing separation is not possible, noticeable artefacts will be generated in the virtual shot gather. As a partial remedy we iteratively use a non-stationary 1D multi-channel matching filter with the interpolated data. Results suggest that a sparse marine seismic survey can yield more information about reflectors if traces are interpolated by interferometry. Comparing our results to those of f-k interpolation shows that the synthetic example gives comparable results while the field example shows better interpolation quality for the interferometric method. © 2013 European Association of Geoscientists & Engineers.

  4. Broadband circular interferometric millimetre-wave ISAR for threat detection

    Directory of Open Access Journals (Sweden)

    S. Bertl

    2007-06-01

    Full Text Available To detect threats on a person's body surface the application of millimetre-waves is possible. In order to get a view of the person from all sides either the person has to be rotated standing on a turntable (Inverse Synthetic Aperture Radar, ISAR or a sensor is moved on a circular path around the person (Synthetic Aperture Radar, SAR. The goal of the reconstruction is to obtain information about the shape of the threats and their positions in all three dimensions. At first the reconstruction is done along range and azimuth, which span the principal surface given by the sensor configuration. This paper reports on two methods to obtain the third spatial dimension. Due to the circular shape and its 3D focussing ability of the aperture this information can be obtained by the evaluation of the image focus. Secondly, if two coherent receiving channels are used, a possibility to achieve 3D spatial resolution is the processing of the interferometric phase. A comparison between these two will be presented.

  5. Interferometric study on the compression region of a magnetoplasma compressor

    Energy Technology Data Exchange (ETDEWEB)

    Astashinskij, V.M.; Kostyukevich, E.A. (AN Belorusskoj SSR, Minsk. Inst. Fiziki)

    High-rate interferometric filming of a compression area of a magnetoplasma compressor of gaseous type has been performed at 1 torr initial pressure of working gas (air) by means of two mirror autocollimation interferometer with visualization of interference field mated with a high-rate photodetector (HRP) operating in the frame-by-frame regime with time resolution not worse than 1 ..mu..s. Frequency of interference picture filming amounted to 375000 frame/second. Space distribution of electron concentrations for different discharge stages have been obtained. Maximum value of electron concentration is achieved at the plasma flow axis and constitutes 2x10/sup 18/ cm/sup -3/. Velocity of plasma boundary motion to the discharge axis and electron concentration gradients in the compression area have been determined. The presented values of electron concentration are in good agreement with results obtained with the spectroscopic method which points to truth of the results and the achieved accuracy of measurements permits to qualitatively compare the theory and experiment.

  6. The linearized inversion of the generalized interferometric multiple imaging

    KAUST Repository

    Aldawood, Ali

    2016-09-06

    The generalized interferometric multiple imaging (GIMI) procedure can be used to image duplex waves and other higher order internal multiples. Imaging duplex waves could help illuminate subsurface zones that are not easily illuminated by primaries such as vertical and nearly vertical fault planes, and salt flanks. To image first-order internal multiple, the GIMI framework consists of three datuming steps, followed by applying the zero-lag cross-correlation imaging condition. However, the standard GIMI procedure yields migrated images that suffer from low spatial resolution, migration artifacts, and cross-talk noise. To alleviate these problems, we propose a least-squares GIMI framework in which we formulate the first two steps as a linearized inversion problem when imaging first-order internal multiples. Tests on synthetic datasets demonstrate the ability to localize subsurface scatterers in their true positions, and delineate a vertical fault plane using the proposed method. We, also, demonstrate the robustness of the proposed framework when imaging the scatterers or the vertical fault plane with erroneous migration velocities.

  7. Interferometric near-infrared spectroscopy (Conference Presentation)

    Science.gov (United States)

    Borycki, Dawid; Kholiqov, Oybek; Chong, Shau Poh; Srinivasan, Vivek J.

    2016-03-01

    We introduce and implement interferometric near-infrared spectroscopy (iNIRS), which simultaneously extracts the optical and dynamic properties of turbid media from the analysis of the spectral interference fringe pattern. The spectral interference fringe pattern is measured using a Mach-Zehnder interferometer with a frequency swept narrow bandwidth light source such that the temporal intensity autocorrelations can be determined for all photon path lengths. This approach enables time-of-flight (TOF) resolved measurement of scatterer motion, which is a feature inaccessible in well-established diffuse correlation spectroscopy techniques. We prove this by analyzing intensity correlations of the light transmitted through diffusive fluid phantoms with photon random walks of up to 55 (approximately 110 scattering events) using laser sweep rates on the order of 100kHz. Thus, the results we present here advance diffuse optical methods by enabling simultaneous determination of depth-resolved optical properties and dynamics in highly scattering samples.

  8. Microstructured optical fiber interferometric breathing sensor.

    Science.gov (United States)

    Favero, Fernando C; Villatoro, Joel; Pruneri, Valerio

    2012-03-01

    In this paper a simple photonic crystal fiber (PCF) interferometric breathing sensor is introduced. The interferometer consists of a section of PCF fusion spliced at the distal end of a standard telecommunications optical fiber. Two collapsed regions in the PCF caused by the splicing process allow the excitation and recombination of a core and a cladding PCF mode. As a result, the reflection spectrum of the device exhibits a sinusoidal interference pattern that instantly shifts when water molecules, present in exhaled air, are adsorbed on or desorbed from the PCF surface. The device can be used to monitor a person's breathing whatever the respiration rate. The device here proposed could be particularly important in applications where electronic sensors fail or are not recommended. It may also be useful in the evaluation of a person's health and even in the diagnosis and study of the progression of serious illnesses such as sleep apnea syndrome. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).

  9. Fundamentals of interferometric gravitational wave detectors

    CERN Document Server

    Saulson, Peter R

    2017-01-01

    LIGO's recent discovery of gravitational waves was headline news around the world. Many people will want to understand more about what a gravitational wave is, how LIGO works, and how LIGO functions as a detector of gravitational waves.This book aims to communicate the basic logic of interferometric gravitational wave detectors to students who are new to the field. It assumes that the reader has a basic knowledge of physics, but no special familiarity with gravitational waves, with general relativity, or with the special techniques of experimental physics. All of the necessary ideas are developed in the book.The first edition was published in 1994. Since the book is aimed at explaining the physical ideas behind the design of LIGO, it stands the test of time. For the second edition, an Epilogue has been added; it brings the treatment of technical details up to date, and provides references that would allow a student to become proficient with today's designs.

  10. Laser-Interferometric Creep Rate Spectroscopy of Polymers

    Science.gov (United States)

    Bershtein, Vladimir A.; Yakushev, Pavel N.

    Laser-interferometric creep rate meter (LICRM) and creep rate spectroscopy (CRS), as an original high-resolution method for discrete relaxation spectrometry and thermal analysis, were developed in the authors' Materials Dynamics Laboratory at Ioffe Physical-Technical Institute of the Russian Academy of Sciences (Saint-Petersburg). In the last few decades they have been successfully applied to solving various problems of polymer physics and materials science, especially being combined with DSC, structural, and other techniques. CRS involves measuring ultra-precisely a creep rate at small tensile or compressive stress, typically much lower than the yield stress, as a function of temperature, over the range from 100 to 800 K. LICRM setup allows one to register precisely creep rates on the basis of deformation increment of 150-300 nm. The survey describes this method and summarizes the results of numerous studies performed with the LICRM setup and CRS technique for different bulk polymeric materials, films, or thin fibers. This approach provided new experimental possibilities superior in resolution and sensitivity compared to the conventional relaxation spectrometry techniques. Among such possibilities are discrete analysis of dynamics; creep on submicro-, micro- and meso-scales; revealing relations between stepwise microplasticity and morphology; kinetic information on creep at any temperature and deformation; polymer dynamics at interfaces; analysis of microplasticity, relaxations, and phase transitions in brittle materials; using creep rate spectra for non-destructive prediction of temperature anomalies in mechanical behavior of materials, etc. Considerable attention has been paid to combined CRS/DSC analysis of the peculiarities of segmental dynamics, nanoscale dynamic, and compositional heterogeneity in different kinds of complex polymer systems and nanocomposites.

  11. Benefits and limitations of imaging multiples: Interferometric and resonant migration

    KAUST Repository

    Guo, Bowen

    2015-07-01

    The benefits and limitations of imaging multiples are reviewed for interferometric migration and resonant migration. Synthetic and field data examples are used to characterize the effectiveness of the methods.

  12. SPECTROSCOPIC AND INTERFEROMETRIC MEASUREMENTS OF NINE K GIANT STARS

    Energy Technology Data Exchange (ETDEWEB)

    Baines, Ellyn K. [Remote Sensing Division, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Döllinger, Michaela P. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Guenther, Eike W.; Hatzes, Artie P. [Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg (Germany); Hrudkovu, Marie [Isaac Newton Group of Telescopes, Apartado de Correos 321, E-387 00 Santa Cruz de la Palma, Canary Islands (Spain); Belle, Gerard T. van, E-mail: ellyn.baines@nrl.navy.mil [Lowell Observatory, Flagstaff, AZ 86001 (United States)

    2016-09-01

    We present spectroscopic and interferometric measurements for a sample of nine K giant stars. These targets are of particular interest because they are slated for stellar oscillation observations. Our improved parameters will directly translate into reduced errors in the final masses for these stars when interferometric radii and asteroseismic densities are combined. Here, we determine each star’s limb-darkened angular diameter, physical radius, luminosity, bolometric flux, effective temperature, surface gravity, metallicity, and mass. When we compare our interferometric and spectroscopic results, we find no systematic offsets in the diameters and the values generally agree within the errors. Our interferometric temperatures for seven of the nine stars are hotter than those determined from spectroscopy with an average difference of about 380 K.

  13. Interferometric crosstalk suppression using polarization multiplexing technique and an SOA

    DEFF Research Database (Denmark)

    Liu, Fenghai; Xueyan, Zheng; Pedersen, Rune Johan Skullerud

    2000-01-01

    Interferometric crosstalk can be greatly suppressed at 10Gb/s and 20Gb/s by using a gain saturated SOA and a polarization multiplexing technique that eliminates impairments like waveform and extinction ratio degradation from the SOA.......Interferometric crosstalk can be greatly suppressed at 10Gb/s and 20Gb/s by using a gain saturated SOA and a polarization multiplexing technique that eliminates impairments like waveform and extinction ratio degradation from the SOA....

  14. Fourier phase demodulation of interferometric fiber sensor

    Science.gov (United States)

    Fu, Xin; Lu, Ping; Liu, Deming; Zhang, Jiangshan

    2017-10-01

    A novel demodulation method for interferometric fiber sensor is proposed in this paper. The physical parameters to be measured by the sensor is obtained by calculating the phase variation of the interference components. The phase variation is computed with the assist of the fast Fourier analysis. For fiber interferometers, most of the energy is contained in the few spatial frequencies corresponding to the components that produce the interference. Therefore, the information of the interference fringe can be presented by the Fourier results at those intrinsic frequencies. Based on this assumption, we proposed a novel method to interrogate the fiber interferometer by calculating the Fourier phase at the spatial frequency. Theoretical derivation proves that the Fourier phase variation is equal to the phase change of the interferometer. Simulation results demonstrate the ability of noise resistance of the proposed method since the information of all wavelength sampling points are adopted for the demodulation process. A Sagnac interferometer based on a section of polarization-maintaining photonic crystal fiber is utilized to verify the feasibility of the phase demodulation technique by lateral pressure sensing. Experimental results of -0.069rad/kPa is acquired.

  15. Calibration Errors in Interferometric Radio Polarimetry

    Science.gov (United States)

    Hales, Christopher A.

    2017-08-01

    Residual calibration errors are difficult to predict in interferometric radio polarimetry because they depend on the observational calibration strategy employed, encompassing the Stokes vector of the calibrator and parallactic angle coverage. This work presents analytic derivations and simulations that enable examination of residual on-axis instrumental leakage and position-angle errors for a suite of calibration strategies. The focus is on arrays comprising alt-azimuth antennas with common feeds over which parallactic angle is approximately uniform. The results indicate that calibration schemes requiring parallactic angle coverage in the linear feed basis (e.g., the Atacama Large Millimeter/submillimeter Array) need only observe over 30°, beyond which no significant improvements in calibration accuracy are obtained. In the circular feed basis (e.g., the Very Large Array above 1 GHz), 30° is also appropriate when the Stokes vector of the leakage calibrator is known a priori, but this rises to 90° when the Stokes vector is unknown. These findings illustrate and quantify concepts that were previously obscure rules of thumb.

  16. The Stability of Chandra Telescope Pointing and Spacial Resolution

    Science.gov (United States)

    Zhao, Ping

    2018-01-01

    Chandra X-ray Observatory revolutionized the X-ray astronomy as being the first, and so far the only, X-ray telescope achieving sub-arcsecond spacial resolution. Chandra is comprised of three principal elements: the High Resolution Mirror Assembly (HRMA), Pointing Control and Aspect Determination (PCAD) system, and the Science Instrument Module (SIM), which is where the X-ray detectors mounted and is connected to the HRMA by a 10-meter long Optical Bench Assembly. To achieve and retain the unprecedented imaging quality, it is critical that these three principal elements to stay rigid and stable for the entire life time of the Chandra operation. I will review the issues of telescope pointing stability, optical Axis, aimpoint and their impacts to the Chandra operation, and evaluate the integrity and stability of the telescope. I will show images taken from all four detectors since launch to demonstrate the quality and stability of the Chandra spacial resolution.

  17. Bendable X-ray Optics for High Resolution Imaging

    Science.gov (United States)

    Gubarev, M.; Ramsey, B.; Kilaru, K.; Atkins, C.; Broadway, D.

    2014-01-01

    Current state-of the-art for x-ray optics fabrication calls for either the polishing of massive substrates into high-angular-resolution mirrors or the replication of thin, lower-resolution, mirrors from perfectly figured mandrels. Future X-ray Missions will require a change in this optics fabrication paradigm in order to achieve sub-arcsecond resolution in light-weight optics. One possible approach to this is to start with perfectly flat, light-weight surface, bend it into a perfect cone, form the desired mirror figure by material deposition, and insert the resulting mirror into a telescope structure. Such an approach is currently being investigated at MSFC, and a status report will be presented detailing the results of finite element analyses, bending tests and differential deposition experiments.

  18. Adaptive Spatial Filtering of Interferometric Data Stack Oriented to Distributed Scatterers

    Science.gov (United States)

    Zhang, Y.; Xie, C.; Shao, Y.; Yuan, M.

    2013-07-01

    Standard interferometry poses a challenge in non-urban areas due to temporal and spatial decorrelation of the radar signal, where there is high signal noise. Techniques such as Small Baseline Subset Algorithm (SBAS) have been proposed to make use of multiple interferometric combinations to alleviate the problem. However, the interferograms used in SBAS are multilooked with a boxcar (rectangle) filter to reduce phase noise, resulting in a loss of resolution and signal superstition from different objects. In this paper, we proposed a modified adaptive spatial filtering algorithm for accurate estimation of interferogram and coherence without resolution loss even in rural areas, to better support the deformation monitoring with time series interferometric synthetic aperture radar (InSAR) technique. The implemented method identifies the statistically homogenous pixels in a neighbourhood based on the goodness-of-fit test, and then applies an adaptive spatial filtering of interferograms. Three statistical tests for the identification of distributed targets will be presented, applied to real data. PALSAR data of the yellow river delta in China is used for demonstrating the effectiveness of this algorithm in rural areas.

  19. Opening a New Window on the Universe: High-Resolution, Long-Wavelength Radio Astronomy

    National Research Council Canada - National Science Library

    Kassim, Namir

    2002-01-01

    Although Jansky's (1933) discovery of radio astronomy was at decametric wavelengths, the urgent quest for ever higher angular resolution and the fact that ionospheric structure limits interferometric imaging to short (less than 5 km...

  20. MEMS Gyroscope with Interferometric Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR Phase I project will develop a MEMS gyroscope that uses an ultra high resolution sensing technique for measuring proof mass motion. The goal is to...

  1. Refractive Index Compensation in Over-Determined Interferometric Systems

    Directory of Open Access Journals (Sweden)

    Zdeněk Buchta

    2012-10-01

    Full Text Available We present an interferometric technique based on a differential interferometry setup for measurement under atmospheric conditions. The key limiting factor in any interferometric dimensional measurement are fluctuations of the refractive index of air representing a dominating source of uncertainty when evaluated indirectly from the physical parameters of the atmosphere. Our proposal is based on the concept of an over-determined interferometric setup where a reference length is derived from a mechanical frame made from a material with a very low thermal coefficient. The technique allows one to track the variations of the refractive index of air on-line directly in the line of the measuring beam and to compensate for the fluctuations. The optical setup consists of three interferometers sharing the same beam path where two measure differentially the displacement while the third evaluates the changes in the measuring range, acting as a tracking refractometer. The principle is demonstrated in an experimental setup.

  2. A simple, low cost interferometric autocorrelator with no moving parts

    Science.gov (United States)

    Kelly, T. J.; Davitt, S. J.; Costello, J. T.

    2016-11-01

    The design and implementation of a low cost interferometric autocorrelator with no moving parts is discussed. It is found that the device is optically simple, uses low cost components and self aligns. The device is used to measure the interferometric autocorrelation of an 800 nm Ti:Sapphire laser pulse produced from an 80 MHz oscillator. The theory and experiment of the design is discussed and compared to results from a commercial autocorrelator. The device is intended for use where pulse to pulse monitoring of the temporal duration is required.

  3. Adaptive interferometric null testing for unknown freeform optics metrology.

    Science.gov (United States)

    Huang, Lei; Choi, Heejoo; Zhao, Wenchuan; Graves, Logan R; Kim, Dae Wook

    2016-12-01

    We report an adaptive interferometric null testing method for overcoming the dynamic range limitations of conventional null testing approaches during unknown freeform optics metrology or optics manufacturing processes that require not-yet-completed surface measurements to guide the next fabrication process. In the presented adaptive method, a deformable mirror functions as an adaptable null component for an unknown optical surface. The optimal deformable mirror's shape is determined by the stochastic parallel gradient descent algorithm and controlled by a deflectometry system. An adaptive interferometric null testing setup was constructed, and its metrology data successfully demonstrated superb adaptive capability in measuring an unknown surface.

  4. Fabricating High-Resolution X-Ray Collimators

    Science.gov (United States)

    Appleby, Michael; Atkinson, James E.; Fraser, Iain; Klinger, Jill

    2008-01-01

    A process and method for fabricating multi-grid, high-resolution rotating modulation collimators for arcsecond and sub-arcsecond x-ray and gamma-ray imaging involves photochemical machining and precision stack lamination. The special fixturing and etching techniques that have been developed are used for the fabrication of multiple high-resolution grids on a single array substrate. This technology has application in solar and astrophysics and in a number of medical imaging applications including mammography, computed tomography (CT), single photon emission computed tomography (SPECT), and gamma cameras used in nuclear medicine. This collimator improvement can also be used in non-destructive testing, hydrodynamic weapons testing, and microbeam radiation therapy.

  5. Optimizing multiplexing scheme in interferometric microscopy

    Science.gov (United States)

    Tayebi, Behnam; Jaferzadeh, Keyvan; Sharif, Farnaz; Han, Jae-Ho

    2016-08-01

    In single exposure off-axis interferometry, multiple information can be recorded by spatial frequency multiplexing. We investigate optimum conditions for designing 2D sampling schemes to record larger field of view in off-axis interferometry multiplexing. The spatial resolution of the recorded image is related to the numerical aperture of the system and sensor pixel size. The spatial resolution should preserve by avoiding crosstalk in the frequency domain. Furthermore, the field of view depends on the sensor size and magnification of the imaging system. In order to preserve resolution and have a larger field of view, the frequency domain should be designed correctly. The experimental results demonstrate that selecting the wrong geometrical scheme in frequency domain decrease the recorded image area.

  6. The EDGE-CALIFA Survey: Interferometric Observations of 126 Galaxies with CARMA

    Science.gov (United States)

    Bolatto, Alberto D.; Wong, Tony; Utomo, Dyas; Blitz, Leo; Vogel, Stuart N.; Sánchez, Sebastián F.; Barrera-Ballesteros, Jorge; Cao, Yixian; Colombo, Dario; Dannerbauer, Helmut; García-Benito, Rubén; Herrera-Camus, Rodrigo; Husemann, Bernd; Kalinova, Veselina; Leroy, Adam K.; Leung, Gigi; Levy, Rebecca C.; Mast, Damián; Ostriker, Eve; Rosolowsky, Erik; Sandstrom, Karin M.; Teuben, Peter; van de Ven, Glenn; Walter, Fabian

    2017-09-01

    We present interferometric CO observations, made with the Combined Array for Millimeter-wave Astronomy (CARMA) interferometer, of galaxies from the Extragalactic Database for Galaxy Evolution survey (EDGE). These galaxies are selected from the Calar Alto Legacy Integral Field Area (CALIFA) sample, mapped with optical integral field spectroscopy. EDGE provides good-quality CO data (3σ sensitivity {{{Σ }}}{mol}˜ 11 {M}⊙ {{pc}}-2 before inclination correction, resolution ˜1.4 kpc) for 126 galaxies, constituting the largest interferometric CO survey of galaxies in the nearby universe. We describe the survey and data characteristics and products, then present initial science results. We find that the exponential scale lengths of the molecular, stellar, and star-forming disks are approximately equal, and galaxies that are more compact in molecular gas than in stars tend to show signs of interaction. We characterize the molecular-to-stellar ratio as a function of Hubble type and stellar mass and present preliminary results on the resolved relations between the molecular gas, stars, and star-formation rate. We then discuss the dependence of the resolved molecular depletion time on stellar surface density, nebular extinction, and gas metallicity. EDGE provides a key data set to address outstanding topics regarding gas and its role in star formation and galaxy evolution, which will be publicly available on completion of the quality assessment.

  7. Spotlight SAR interferometry for terrain elevation mapping and interferometric change detection

    Energy Technology Data Exchange (ETDEWEB)

    Eichel, P.H.; Ghiglia, D.C.; Jakowatz, C.V. Jr. [and others

    1996-02-01

    In this report, we employ an approach quite different from any previous work; we show that a new methodology leads to a simpler and clearer understanding of the fundamental principles of SAR interferometry. This methodology also allows implementation of an important collection mode that has not been demonstrated to date. Specifically, we introduce the following six new concepts for the processing of interferometric SAR (INSAR) data: (1) processing using spotlight mode SAR imaging (allowing ultra-high resolution), as opposed to conventional strip-mapping techniques; (2) derivation of the collection geometry constraints required to avoid decorrelation effects in two-pass INSAR; (3) derivation of maximum likelihood estimators for phase difference and the change parameter employed in interferometric change detection (ICD); (4) processing for the two-pass case wherein the platform ground tracks make a large crossing angle; (5) a robust least-squares method for two-dimensional phase unwrapping formulated as a solution to Poisson`s equation, instead of using traditional path-following techniques; and (6) the existence of a simple linear scale factor that relates phase differences between two SAR images to terrain height. We show both theoretical analysis, as well as numerous examples that employ real SAR collections to demonstrate the innovations listed above.

  8. Progress Toward A Very High Angular Resolution Imaging Spectrometer (VERIS)

    Science.gov (United States)

    Korendyke, Clarence M.; Vourlidas, A.; Landi, E.; Seely, J.; Klimchuck, J.

    2007-07-01

    Recent imaging at arcsecond (TRACE) and sub-arcsecond (VAULT) spatial resolution clearly show that structures with fine spatial scales play a key role in the physics of the upper solar atmosphere. Both theoretical and observational considerations point to the importance of small spatial scales, impulsive energy release, strong dynamics, and extreme plasma nonuniformity. Fundamental questions regarding the nature, structure, properties and dynamics of loops and filamentary structures in the upper atmosphere have been raised. To address these questions, we are developing a next generation, VEry high angular Resolution Imaging Spectrometer (VERIS) as a sounding rocket instrument. VERIS will obtain the necessary high spatial resolution, high fidelity measurements of plasma temperatures, densities and velocities. With broad simultaneous temperature coverage, the VERIS observations will directly address unresolved issues relating to interconnections of various temperature solar plasmas. VERIS will provide the first ever subarcsecond spectra of transition region and coronal structures. It will do so with a sufficient spectral resolution of to allow centroided Doppler velocity determinations to better than 3 km/s. VERIS uses a novel two element, normal incidence optical design with highly reflective EUV coatings to access a spectral range with broad temperature coverage (0.03-15 MK) and density-sensitive line ratios. Finally, in addition to the spectra, VERIS will simultaneously obtain spectrally pure slot images (10x150 arcsec) in the +/-1 grating orders, which can be combined to make instantaneous line-of-sight velocity maps with 8km/s accuracy over an unprecedented field of view. The VERIS program is beginning the second year of its three year development cycle. All design activities and reviews are complete. Fabrication of all major components has begun. Brassboard electronics cards have been fabricated, assembled and tested. The paper presents the essential scientific

  9. Exploratory submm space radio-interferometric telescope

    NARCIS (Netherlands)

    de Graauw, T; Helmich, FP; Cernicharo, J; Wild, W; Baryshev, A; Bos, A; den Herder, JW; Gunst, A; Jackson, B; van Langevelde, HJ; Maat, P; Martin-Pintado, J; Noordam, J; Quirrenbach, A; Roelfsema, PR; Wesselius, PR; Yagoubov, P; Venema, Lars; Wesselius, PR; Encrenaz, T

    2005-01-01

    Angular resolution in the far-infrared (FIR) wavelength regime limits the range of size scales accessible although the FIR range has become of prime importance for astrophysics. Observations of ionic, atomic and molecular lines, many of them only present in the FIR spectral region, provide important

  10. Effect of external digital elevation model on monitoring of mine subsidence by two-pass differential interferometric synthetic aperture radar

    Science.gov (United States)

    Tao, Qiuxiang; Gao, Tengfei; Liu, Guolin; Wang, Zhiwei

    2017-04-01

    The external digital elevation model (DEM) error is one of the main factors that affect the accuracy of mine subsidence monitored by two-pass differential interferometric synthetic aperture radar (DInSAR), which has been widely used in monitoring mining-induced subsidence. The theoretical relationship between external DEM error and monitored deformation error is derived based on the principles of interferometric synthetic aperture radar (DInSAR) and two-pass DInSAR. Taking the Dongtan and Yangcun mine areas of Jining as test areas, the difference and accuracy of 1:50000, ASTER GDEM V2, and SRTM DEMs are compared and analyzed. Two interferometric pairs of Advanced Land Observing Satellite Phased Array L-band SAR covering the test areas are processed using two-pass DInSAR with three external DEMs to compare and analyze the effect of three external DEMs on monitored mine subsidence in high- and low-coherence subsidence regions. Moreover, the reliability and accuracy of the three DInSAR-monitored results are compared and verified with leveling-measured subsidence values. Results show that the effect of external DEM on mine subsidence monitored by two-pass DInSAR is not only related to radar look angle, perpendicular baseline, slant range, and external DEM error, but also to the ground resolution of DEM, the magnitude of subsidence, and the coherence of test areas.

  11. An error prediction framework for interferometric SAR data

    DEFF Research Database (Denmark)

    Mohr, Johan Jacob; Merryman Boncori, John Peter

    2008-01-01

    Three of the major error sources in interferometric synthetic aperture radar measurements of terrain elevation and displacement are baseline errors, atmospheric path length errors, and phase unwrapping errors. In many processing schemes, these errors are calibrated out by using ground control poi...

  12. Interferometric key readable security holograms with secrete-codes

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 68; Issue 3. Interferometric ... A K Aggarwal1. Coherent Optics Division, Central Scientific Instruments Organisation, Sector 30, Chandigarh 160 030, India; Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125 001, India ...

  13. Tropical forest mapping using polarimetric and interferometric SAR data

    NARCIS (Netherlands)

    Prakoso, K.U.

    2006-01-01

    A study was made of the potential of the combined use of C-, L- and P-band polarimetric and C- and L-band interferometric airborne SAR data for tropical forest mapping. These data were collected with the NASA/JPL AirSAR during the PacRim-2 2000 campaign in Indonesia. The Sungai Wain forest reserve

  14. Interferometric direction finding with a metamaterial detector

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, Suresh; Schurig, David, E-mail: david.schurig@utah.edu [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Shrekenhamer, David; Padilla, Willie [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Xu, Wangren; Sonkusale, Sameer [Department of Electrical and Computer Engineering, Tufts University, Medford, Massachusetts 02155 (United States)

    2013-12-16

    We present measurements and analysis demonstrating useful direction finding of sources in the S band (2–4 GHz) using a metamaterial detector. An augmented metamaterial absorber that supports magnitude and phase measurement of the incident electric field, within each unit cell, is described. The metamaterial is implemented in a commercial printed circuit board process with off-board back-end electronics. We also discuss on-board back-end implementation strategies. Direction finding performance is analyzed for the fabricated metamaterial detector using simulated data and the standard algorithm, MUtiple SIgnal Classification. The performance of this complete system is characterized by its angular resolution as a function of radiation density at the detector. Sources with power outputs typical of mobile communication devices can be resolved at kilometer distances with sub-degree resolution and high frame rates.

  15. Reduced-Resolution Radar Imagery, Digital Elevation Models, and Related GIS Layers for Barrow, Alaska, USA, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This product set contains reduced-resolution Interferometric Synthetic Aperture Radar (IFSAR) imagery and geospatial data for the Barrow Peninsula (155.39 - 157.48...

  16. Interferometric fiber-optic bending / nano-displacement sensor using plastic dual-core fiber

    CERN Document Server

    Qu, H; Skorobogatiy, M

    2014-01-01

    We demonstrate an interferometric fiber-optic bending/micro-displacement sensor based on a plastic dual-core fiber with one end coated with a silver mirror. The two fiber cores are first excited with the same laser beam, the light in each core is then back-reflected at the mirror-coated fiber-end, and, finally, the light from the two cores is made to interfere at the coupling end. Bending of the fiber leads to shifting interference fringes that can be interrogated with a slit and a single photodetector. We find experimentally that the resolution of our bending sensor is ~3x10-4 m-1 for sensing of bending curvature, as well as ~70 nm for sensing of displacement of the fiber tip. We demonstrate operation of our sensor using two examples. One is weighting of the individual micro-crystals of salt, while the other one is monitoring dynamics of isopropanol evaporation.

  17. Current Development in Airborne Repeat-pass Interferometric Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Zhong Xue-lian

    2013-09-01

    Full Text Available Due to its agility, flexibility and accuracy, airborne repeat-pass Interferometric Synthetic Aperture Radar (InSAR is capable of overcoming the disadvantages of long revisit time and low resolution in space-borne SAR interferometry, and play an irreplaceable role in monitoring the deformation of landslides, volcanoes, earthquakes, etc. In this paper, the history and status in the world wide about the technology of airborne repeat-pass SAR interferometry are reviewed detailedly. Then after the accuracy of this technology is analyzed, its key problems in practice are presented, and the related researches in this field are also introduced comprehensively. The development trend and the prospect of this technology are also described in this paper. Finally, it is pointed that several problems still need to be studied further for accurate parameter inversion.

  18. Characterization of GEM foils and materials simulation, measurements and interferometric monitoring tools

    CERN Document Server

    Benussi, Luigi

    2015-01-01

    The GE1/1 CMS project consists of 144 GEM chambers of about 0.5 qm active area each, based on the triple GEMs technology, to be installed in the very forward region of the CMS endcap during the long shutdown of LHC in 2108-2019. GE1/1 chambers will be operated for decades in harsh environment, and are expected to perform consistently providing good space and time resolution and excellent rate capabilities. An extensive material science simulation and measurement campaign is in progress to characterize GEM materials, with main focus on the GEM foils. Results are presented on full Finite Element Analysis simulations, measurement of tensile properties and humidity absorption coefficients, both for unused and irradiated samples. Preliminary results are shown on interferometric methods based on Moirè fringes for the monitoring of GEM foils mechanical properties during chamber construction.

  19. TELAER: a multi-mode/multi-antenna interferometric airborne SAR system

    Science.gov (United States)

    Perna, Stefano; Amaral, Tiago; Berardino, Paolo; Esposito, Carmen; Jackson, Giuseppe; Pauciullo, Antonio; Vaz Junior, Eurico; Wimmer, Christian; Lanari, Riccardo

    2014-05-01

    The present contribution is aimed at showing the capabilities of the TELAER airborne Synthetic Aperture Radar (SAR) system recently upgraded to the interferometric mode [1]. TELAER is an Italian airborne X-Band SAR system, mounted onboard a LearJet 35A aircraft. Originally equipped with a single TX/RX antenna, it now operates in single-pass interferometric mode thanks to a system upgrading [1] funded by the Italian National Research Council (CNR), via the Italian Ministry of Education, Universities and Research (MIUR), in the framework of a cooperation between CNR and the Italian Agency for Agriculture Subsidy Payments (AGEA). In the frame of such cooperation, CNR has entrusted the Institute for Electromagnetic Sensing of the Environment (IREA) for managing all the activities, included the final flight tests, related to the system upgrading. According to such an upgrading, two additional receiving X-band antennas have been installed in order to allow, simultaneously, single-pass Across-Track and Along-Track interferometry [1]. More specifically, the three antennas are now installed in such a way to produce three different across-track baselines and two different along-track baselines. Moreover, in the frame of the same system upgrading, it has been mounted onboard the Learjet an accurate embedded Global Navigation Satellite System and Inertial Measurement Unit equipment. This allows precise measurement of the tracks described by the SAR antennas during the flight, in order to accurately implement Motion Compensation (MOCO) algorithms [2] during the image formation (focusing) step. It is worth remarking that the TELAER system upgraded to the interferometric mode is very flexible, since the user can set different operational modes characterized by different geometric resolutions and range swaths. In particular, it is possible to reach up to 0.5 m of resolution with a range swath of 2km; conversely, it is possible to enlarge the range swath up to 10 km at expenses of

  20. Compressed sensing reconstruction of a string signal from interferometric observations of the cosmic microwave background

    Science.gov (United States)

    Wiaux, Y.; Puy, G.; Vandergheynst, P.

    2010-03-01

    We propose an algorithm for the reconstruction of the signal induced by cosmic strings in the cosmic microwave background (CMB), from radio-interferometric data at arcminute resolution. Radio interferometry provides incomplete and noisy Fourier measurements of the string signal, which exhibits sparse or compressible magnitude of the gradient due to the Kaiser-Stebbins effect. In this context, the versatile framework of compressed sensing naturally applies for solving the corresponding inverse problem. Our algorithm notably takes advantage of a model of the prior statistical distribution of the signal fitted on the basis of realistic simulations. Enhanced performance relative to the standard CLEAN algorithm is demonstrated by simulated observations under noise conditions including primary and secondary CMB anisotropies.

  1. Dynamic full field optical coherence tomography: subcellular metabolic contrast revealed in tissues by temporal analysis of interferometric signals

    CERN Document Server

    Apelian, Clement; Thouvenin, Olivier; Boccara, A Claude

    2016-01-01

    We developed a new endogenous approach to reveal subcellular metabolic contrast in fresh ex vivo tissues taking advantage of the time dependence of the full field optical coherence tomography interferometric signals. This method reveals signals linked with local activity of the endogenous scattering elements which can reveal cells where other imaging techniques fail or need exogenous contrast agents. We benefit from the micrometric transverse resolution of full field OCT to image intracellular features. We used this time dependence to identify different dynamics at the millisecond scale on a wide range of organs in normal or pathological conditions.

  2. Interferometric fiber Bragg grating shift demodulation

    Science.gov (United States)

    Stepien, Karol; Jóźwik, Michalina; Nasilowski, Tomasz

    2015-09-01

    In this paper we present a fiber Bragg grating shift demodulator with changeable resolution based on an unbalanced fiber Mach-Zehnder interferometer. Preliminary research proves phase sensitivity to Bragg wavelength changes of 6,83 rad/mɛ. Phase sensitivity can be modified by changing the optical path difference witch is only limited by the coherence length of light reflected by the fiber Bragg grating. This solution can be used as a single sensor or as a part of a more complex system.

  3. Surface-mount sapphire interferometric temperature sensor

    Science.gov (United States)

    Zhu, Yizheng; Wang, Anbo

    2006-08-01

    A fiber-optic high-temperature sensor is demonstrated by bonding a 45°-polished single-crystal sapphire fiber on the surface of a sapphire wafer, whose optical thickness is temperature dependent and measured by white-light interferometry. A novel adhesive-free coupling between the silica and sapphire fibers is achieved by fusion splicing, and its performance is characterized. The sensor's interference signal is investigated for its dependence on angular alignment between the fiber and the wafer. A prototype sensor is tested to 1170 °C with a resolution of 0.4 °C, demonstrating excellent potential for high-temperature measurement.

  4. The 2001 U.S. Naval Observatory Double Star CD-Rom. III. The Third Catalog of Interferometric Measurements of Binary Stars

    Science.gov (United States)

    2001-12-01

    The Third Catalog of Interferometric Measurements of Binary Stars includes all published measures of binary and multiple star systems obtained by high-resolution techniques (speckle interferometry, photoelectric occultation timings, etc.), as well as negative examinations for duplicity, as of 2001 January 1. This catalog is one of four USNO double star catalogs to be included on a new CD-ROM. A brief summary and statistical analysis of the contents of the catalog are presented.

  5. REVIEW ARTICLE: The transmission interferometric adsorption sensor

    Science.gov (United States)

    Heuberger, M.; Balmer, T. E.

    2007-12-01

    This paper describes a high-speed adsorption sensor based on thin-film interference at the interfaces. The sensor can be used as a stand-alone instrument or in combination with a direct surface force measurement, which yields a wide range of additional information on molecular interactions on adsorbed films. The achieved mass resolution of the presented method (1-10 ng cm-2 Hz-1/2) is comparable to or better than other modern bio-sensors. The dependence of mass resolution on various factors is presented and demonstrated in a number of relevant examples. The described method is suitable for the implementation of a low-cost bio-sensor with a minimal number of optical elements. The measurement spot size is one micrometre or more and sampling rates >10 Hz are readily possible. In contrast to other bio-sensors, the signal baseline has a remarkable long-term stability since the measured signal is virtually independent of refractive index changes in the fluid medium above the sensor surface. In combination with an optical spectral correlation method, the classical computer calculations are substituted by an optical calculator and a label-free real-time imaging adsorption sensor is realized. We demonstrate sensor operation both inside the extended surface forces apparatus as well as in a stand-alone bio-sensor configuration. As a final point, we illustrate the imaging capability of this new sensor technology on a patterned bio-functionalized surface.

  6. rtpipe: Searching for Fast Radio Transients in Interferometric Data

    Science.gov (United States)

    Law, Casey J.

    2017-06-01

    rtpipe (real-time pipeline) analyzes radio interferometric data with an emphasis on searching for transient or variable astrophysical sources. The package combines single-dish concepts such as dedispersion and filters with interferometric concepts, including images and the uv-plane. In contrast to time-domain data recorded with large single-dish telescopes, visibilities from interferometers can precisely localize sources anywhere in the entire field of view. rtpipe opens interferometers to the study of fast transient sky, including sources like pulsars, stellar flares, rotating radio transients, and fast radio bursts. Key portions of the search pipeline, such as image generation and dedispersion, have been accelerated. That, in combination with its multi-threaded, multi-node design, makes rtpipe capable of searching millisecond timescale data in real time on small compute clusters.

  7. Synchronous interferometric demodulation of Placido mires applied to corneal topography

    CERN Document Server

    Servin, Manuel

    2012-01-01

    This paper presents a novel digital interferometric method to demodulate Placido fringe patterns. This is a synchronous method which uses a computer-stored conic-wavefront as demodulating reference. Here we focuses on the experimental aspects to phase-demodulate Placido mires applied to corneal topography. This synchronous method is applied to two topographic Placido images and their de-modulated corneal-slope deformation is estimated. This conic-interferometric method is highly robust against typical "noisy" signals in Placido topography such as: reflected eyelashes and iris structures. That is because the eyelashes and the iris structure are high frequency "noisy" signals corrupting the reflected Placido mire, so they are filtered-out by this method. Digital synchronous interferometry is here applied for the first time to demodulate corneal topographic concentric-rings images (Patent pending at the USPTO).

  8. Interferometric fiber optic sensors for biomedical applications of optoacoustic imaging.

    Science.gov (United States)

    Lamela, Horacio; Gallego, Daniel; Gutierrez, Rebeca; Oraevsky, Alexander

    2011-03-01

    We present a non-metallic interferometric silica optical fiber ultrasonic wideband sensor for optoacoustic imaging applications. The ultrasonic sensitivity of this sensor has been characterized over the frequency range from 1 to 10 MHz. A comparative analysis has been carried out between this sensor and an array of piezoelectric transducers using optoacoustic signals generated from an optical absorbent embedded in a tissue mimicking phantom. Also, a two dimensional reconstructed image of the phantom using the fiber interferometric sensor is presented and compared to the image obtained using the Laser Optoacoustic Imaging System, LOIS-64B. The feasibility of our fiber optic based sensor for wideband ultrasonic detection is demonstrated. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Rapid interferometric imaging of printed drug laden multilayer structures

    DEFF Research Database (Denmark)

    Sandler, Niklas; Kassamakov, Ivan; Ehlers, Henrik

    2014-01-01

    /and active pharmaceutical ingredients (API) adhere to each other. This is crucial in order to have predetermined drug release profiles. We also demonstrate non-invasive measurement of a polymer structure in a microfluidic channel. It shown that traceable interferometric 3D microscopy is a viable technique......The developments in printing technologies allow fabrication of micron-size nano-layered delivery systems to personal specifications. In this study we fabricated layered polymer structures for drug-delivery into a microfluidic channel and aimed to interferometrically assure their topography...... and adherence to each other. We present a scanning white light interferometer (SWLI) method for quantitative assurance of the topography of the embedded structure. We determined rapidly in non-destructive manner the thickness and roughness of the structures and whether the printed layers containing polymers or...

  10. Full-field interferometric confocal microscopy using a VCSEL array.

    Science.gov (United States)

    Redding, Brandon; Bromberg, Yaron; Choma, Michael A; Cao, Hui

    2014-08-01

    We present an interferometric confocal microscope using an array of 1200 vertical cavity surface emitting lasers (VCSELs) coupled to a multimode fiber. Spatial coherence gating provides ~18,000 continuous virtual pinholes, allowing an entire en face plane to be imaged in a snapshot. This approach maintains the same optical sectioning as a scanning confocal microscope without moving parts, while the high power of the VCSEL array (∼5  mW per laser) enables high-speed image acquisition with integration times as short as 100 μs. Interferometric detection also recovers the phase of the image, enabling quantitative phase measurements and improving the contrast when imaging phase objects.

  11. Spatial resolution limits of an optical profiler

    Science.gov (United States)

    Creath, Katherine

    1990-07-01

    Interferometric optical profilers have a spatial resolution which is either limited by the detector array sample spacing and element size or by the optical resolution of the system. To test the working spatial resolution of an optical profiler a sinsusoidal grating with 300 lines/mm was measured using an optical profiler at lOx 2Ox 40x and 200x with detector arrays having element-to-element spacings of 6. 8 j. tm and 40 tm. The highest magnification gave the greatest and most accurate depth for the grating for all of the detectors. At 40x as long as there were more than about 8 sample points per cycle as there were with the two smaller detector spacings the grating depth can be measured quite accurately. With fewer points the peak-to-valley height measurement of the grating is too low even though the optical resolution of the system is sufficient enough to resolve the grating. The results of this work show that for accurate representation of surface heights containing high frequency structures oversampling is desirable. Summary The spatial resolution of an interferometric optical proffler depends upon both the optical resolution of the system and the characteristics of the detector array used to sample the image. The limiting resolution wifi be the larger of the optical and detector resolution. One means of defining optical resolution is the Sparrow criterion which states that the image of two points is just

  12. Interferometric tomography of fuel cells for monitoring membrane water content.

    Science.gov (United States)

    Waller, Laura; Kim, Jungik; Shao-Horn, Yang; Barbastathis, George

    2009-08-17

    We have developed a system that uses two 1D interferometric phase projections for reconstruction of 2D water content changes over time in situ in a proton exchange membrane (PEM) fuel cell system. By modifying the filtered backprojection tomographic algorithm, we are able to incorporate a priori information about the object distribution into a fast reconstruction algorithm which is suitable for real-time monitoring.

  13. Magnonic interferometric switch for multi-valued logic circuits

    Science.gov (United States)

    Balynsky, Michael; Kozhevnikov, Alexander; Khivintsev, Yuri; Bhowmick, Tonmoy; Gutierrez, David; Chiang, Howard; Dudko, Galina; Filimonov, Yuri; Liu, Guanxiong; Jiang, Chenglong; Balandin, Alexander A.; Lake, Roger; Khitun, Alexander

    2017-01-01

    We investigated a possible use of the magnonic interferometric switches in multi-valued logic circuits. The switch is a three-terminal device consisting of two spin channels where input, control, and output signals are spin waves. Signal modulation is achieved via the interference between the source and gate spin waves. We report experimental data on a micrometer scale prototype based on the Y3Fe2(FeO4)3 structure. The output characteristics are measured at different angles of the bias magnetic field. The On/Off ratio of the prototype exceeds 13 dB at room temperature. Experimental data are complemented by the theoretical analysis and the results of micro magnetic simulations showing spin wave propagation in a micrometer size magnetic junction. We also present the results of numerical modeling illustrating the operation of a nanometer-size switch consisting of just 20 spins in the source-drain channel. The utilization of spin wave interference as a switching mechanism makes it possible to build nanometer-scale logic gates, and minimize energy per operation, which is limited only by the noise margin. The utilization of phase in addition to amplitude for information encoding offers an innovative route towards multi-state logic circuits. We describe possible implementation of the three-value logic circuits based on the magnonic interferometric switches. The advantages and shortcomings inherent in interferometric switches are also discussed.

  14. Laser characteristics and interferometric process and sensor applications

    Science.gov (United States)

    Glatz, Otto

    2005-04-01

    Begin Fiber Bragg Gratings (FBGs) are basic elements in DWDM technology. They are produced by UV illumination. UV light sources have been steadily improved to meet the demands of FBG writing industry. We want to characterize some parameters of interest of a simple, line-narrowed excimer laser source, its improvements and contribution to interferometric non-proximity FBG writing. Parameters of interest to be discussed are the temporal and spatial coherence length, the beam stability and spectrum control of produced FBG. With a temporal coherence length of ~ 5 mm it is possible to utilize cost efficient excimer laser technology for the interferometric non-proximity FBG writing process. Correspondingly the line-narrowed Excimer laser can replace expensive frequency doubled Argon ion lasers driving interferometric FBG writing set-ups in production and R & D. Beyond it FBGs for sensor applications play an important role. They have the potential for the measurement of strain / deformation and temperature with applications including monitoring of highways, bridges, aerospace components and chemical and biological sensors. We want to discuss the requirements for excimer lasers for this application: The spatial coherence length, beam profile, pointing and energy stability.

  15. An Inexpensive Interferometric Setup for Measuring Microscopic Displacements

    Science.gov (United States)

    Alanís, Elvio; Romero, Graciela; Martínez, Carlos; Álvarez, Liliana; Salazar, Germán

    2004-04-01

    In an interesting article published in an issue of The Physics Teacher, Reichert gives some didactic examples about static friction force between a plastic block and a wooden plane on which it rests. To explain the experiments, he uses a simple model based on a microscopic "elastic band" that connects the atoms of both surfaces. Reichert remarks that "the block moves, albeit a microscopic distance," and that it would be helpful if the student could see these displacements. In another paragraph he states that "measuring it (displacement) requires delicate and expensive optical instruments." Effectively, a measurement of such small displacements generally requires interferometric devices. At our university, we teach basic physics and we are aware of the difficulties that beginners have grasping the concepts involved in static friction force. At the same time, as our research field is related to optics metrology, we could not ignore Reichert's statement. Could we design an experimental device to measure the microscopic displacement referred to by Reichert, keeping it inexpensive and easy to implement? Incidentally, in the same issue of The Physics Teacher, Sawicki2 gives an excellent example of how, with a few common elements, a simple experiment of interferometric measurement can be put within students' reach. In this paper, we suggest the use of a simple interferometric device, built with very common and inexpensive elements, and describe an experiment on static friction force in which the instrument is applied to measure microscopic displacements.

  16. Iterated unscented Kalman filter for phase unwrapping of interferometric fringes.

    Science.gov (United States)

    Xie, Xianming

    2016-08-22

    A fresh phase unwrapping algorithm based on iterated unscented Kalman filter is proposed to estimate unambiguous unwrapped phase of interferometric fringes. This method is the result of combining an iterated unscented Kalman filter with a robust phase gradient estimator based on amended matrix pencil model, and an efficient quality-guided strategy based on heap sort. The iterated unscented Kalman filter that is one of the most robust methods under the Bayesian theorem frame in non-linear signal processing so far, is applied to perform simultaneously noise suppression and phase unwrapping of interferometric fringes for the first time, which can simplify the complexity and the difficulty of pre-filtering procedure followed by phase unwrapping procedure, and even can remove the pre-filtering procedure. The robust phase gradient estimator is used to efficiently and accurately obtain phase gradient information from interferometric fringes, which is needed for the iterated unscented Kalman filtering phase unwrapping model. The efficient quality-guided strategy is able to ensure that the proposed method fast unwraps wrapped pixels along the path from the high-quality area to the low-quality area of wrapped phase images, which can greatly improve the efficiency of phase unwrapping. Results obtained from synthetic data and real data show that the proposed method can obtain better solutions with an acceptable time consumption, with respect to some of the most used algorithms.

  17. Atomic Interferometric Gravitational-Wave Space Observatory (AIGSO)

    Science.gov (United States)

    Gao, Dong-Feng; Wang, Jin; Zhan, Ming-Sheng

    2018-01-01

    We propose a space-borne gravitational-wave detection scheme, called atom interferometric gravitational-wave space observatory (AIGSO). It is motivated by the progress in the atomic matter-wave interferometry, which solely utilizes the standing light waves to split, deflect and recombine the atomic beam. Our scheme consists of three drag-free satellites orbiting the Earth. The phase shift of AIGSO is dominated by the Sagnac effect of gravitational-waves, which is proportional to the area enclosed by the atom interferometer, the frequency and amplitude of gravitational-waves. The scheme has a strain sensitivity ground-based laser interferometric detectors. Thus, our proposed AIGSO can be a good complementary detection scheme to the space-borne laser interferometric schemes, such as LISA. Considering the current status of relevant technology readiness, we expect our AIGSO to be a promising candidate for the future space-based gravitational-wave detection plan. Supported by the National Key Research Program of China under Grant No. 2016YFA0302002, the National Science Foundation of China under Grant Nos. 11227803 and 91536221, and the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No. XDB21010100

  18. Interferometric characterization of tear film dynamics

    Science.gov (United States)

    Primeau, Brian Christopher

    The anterior refracting surface of the eye is the thin tear film that forms on the surface of the cornea. When a contact lens is on worn, the tear film covers the contact lens as it would a bare cornea, and is affected by the contact lens material properties. Tear film irregularity can cause both discomfort and vision quality degradation. Under normal conditions, the tear film is less than 10 microns thick and the thickness and topography change in the time between blinks. In order to both better understand the tear film, and to characterize how contact lenses affect tear film behavior, two interferometers were designed and built to separately measure tear film behavior in vitro and in vivo. An in vitro method of characterizing dynamic fluid layers applied to contact lenses mounted on mechanical substrates has been developed using a phase-shifting Twyman-Green interferometer. This interferometer continuously measures light reflected from the surface of the fluid layer, allowing precision analysis of the dynamic fluid layer. Movies showing this fluid layer behavior can be generated. The fluid behavior on the contact lens surface is measured, allowing quantitative analysis beyond what typical contact angle or visual inspection methods provide. The in vivo interferometer is a similar system, with additional modules included to provide capability for human testing. This tear film measurement allows analysis beyond capabilities of typical fluorescein visual inspection or videokeratometry and provides better sensitivity and resolution than shearing interferometry methods.

  19. High-Resolution Broadband Spectral Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D J; Edelstein, J

    2002-08-09

    We demonstrate solar spectra from a novel interferometric method for compact broadband high-resolution spectroscopy. The spectral interferometer (SI) is a hybrid instrument that uses a spectrometer to externally disperse the output of a fixed-delay interferometer. It also has been called an externally dispersed interferometer (EDI). The interferometer can be used with linear spectrometers for imaging spectroscopy or with echelle spectrometers for very broad-band coverage. EDI's heterodyning technique enhances the spectrometer's response to high spectral-density features, increasing the effective resolution by factors of several while retaining its bandwidth. The method is extremely robust to instrumental insults such as focal spot size or displacement. The EDI uses no moving parts, such as purely interferometric FTS spectrometers, and can cover a much wider simultaneous bandpass than other internally dispersed interferometers (e.g. HHS or SHS).

  20. Calibration of a high spatial resolution laser two-color heterodyne interferometer for density profile measurements in the TJ-II stellarator.

    Science.gov (United States)

    Acedo, Pablo; Pedreira, P; Criado, A R; Lamela, Horacio; Sánchez, Miguel; Sánchez, Joaquín

    2008-10-01

    A high spatial resolution two-color (CO(2), lambda=10.6 microm, He-Ne, lambda=633 nm) interferometer for density profile measurements in the TJ-II stellarator is under development and installation, based in the currently operational single channel two-color heterodyne interferometer. To achieve the objectives of 32 channels, with 4-5 mm lateral separation between plasma chords, careful design and calibration of the interferometric waveforms for both the measurement and vibration compensation wavelengths are undertaken. The first step has been to set up in our laboratories an expanded-beam heterodyne/homodyne interferometer to evaluate the quality of both interferometric wavefronts, a reported source of poor vibration compensation and thus low resolution in the density profile measurements. This novel interferometric setup has allowed us to calibrate the spatial resolution in the profile measurements resulting in approximately 2 mm lateral resolution in the reconstruction of the interferometric wavefront.

  1. Demonstration of Interferometric SAR Onboard Processing for Planetary Mapping Missions Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This task will enable future planetary mapping missions through a technique called interferometric synthetic aperture radar, using microwave and triangulation to...

  2. In situ non-destructive measurement of biofilm thickness and topology in an interferometric optical microscope

    Energy Technology Data Exchange (ETDEWEB)

    Larimer, Curtis [Pacific Northwest National Laboratory, Battelle for the USDOE, PO Box 999, MSIN P7-50 Richland WA 99354 USA; Suter, Jonathan D. [Pacific Northwest National Laboratory, Battelle for the USDOE, PO Box 999, MSIN P7-50 Richland WA 99354 USA; Bonheyo, George [Pacific Northwest National Laboratory, Battelle for the USDOE, PO Box 999, MSIN P7-50 Richland WA 99354 USA; Addleman, Raymond Shane [Pacific Northwest National Laboratory, Battelle for the USDOE, PO Box 999, MSIN P7-50 Richland WA 99354 USA

    2016-03-15

    Biofilms are ubiquitous and deleteriously impact a wide range of industrial processes, medical and dental health issues, and environmental problems such as transport of invasive species and the fuel efficiency of ocean going vessels. Biofilms are difficult to characterize when fully hydrated, especially in a non-destructive manner, because of their soft structure and water-like bulk properties. Herein we describe a non-destructive high resolution method of measuring and monitoring the thickness and topology of live biofilms of using white light interferometric optical microscopy. Using this technique, surface morphology, surface roughness, and biofilm thickness can be measured non-destructively and with high resolution as a function of time without disruption of the biofilm activity and processes. The thickness and surface topology of a P. putida biofilm were monitored growing from initial colonization to a mature biofilm. Typical bacterial growth curves were observed. Increase in surface roughness was a leading indicator of biofilm growth.

  3. New orbital elements of 5 interferometric double stars

    Directory of Open Access Journals (Sweden)

    Olević D.

    1999-01-01

    Full Text Available In this paper, for the first time, are presented elliptical and Thiel- Innes orbitatal elements for the following interferometric pairs: WDS 00416+2438 = WRH, WDS 03271+1845 = CHARA 10, WDS 04044+2406 = McA 13 Aa, WDS 17095+4047 = McA 45 and WDS 23019+4219 = o And Aa. For the pairs WDS 03271+1845 = CHARA 10 andWDS 04044+2406 = McA 13 Aa are calculated total masses and dynamical parallaxes which are compared with corresponding Hipparcos parallaxes.

  4. Imaging Stars by Performing Full-Stokes Optical Interferometric Polarimetry

    Directory of Open Access Journals (Sweden)

    Nicholas M. Elias II

    2012-03-01

    Full Text Available Optical interferometry and polarimetry have separately provided new insights into stellar astronomy, especially in the fields of fundamental parameters and atmospheric models. We present: scientific justifications for “full-Stokes” optical interferometric polarimetry (OIP; updated instrument requirements; preliminary beam combiner designs; polarimeter design; end-to-end OIP data reduction; and realistic reimaged full-Stokes models of Be stars with a suitable number of telescopes plus noise sources. All of this work represents preliminary research to construct an OIP beam combiner.

  5. Interferometric millimeter wave and THz wave doppler radar

    Science.gov (United States)

    Liao, Shaolin; Gopalsami, Nachappa; Bakhtiari, Sasan; Raptis, Apostolos C.; Elmer, Thomas

    2015-08-11

    A mixerless high frequency interferometric Doppler radar system and methods has been invented, numerically validated and experimentally tested. A continuous wave source, phase modulator (e.g., a continuously oscillating reference mirror) and intensity detector are utilized. The intensity detector measures the intensity of the combined reflected Doppler signal and the modulated reference beam. Rigorous mathematics formulas have been developed to extract bot amplitude and phase from the measured intensity signal. Software in Matlab has been developed and used to extract such amplitude and phase information from the experimental data. Both amplitude and phase are calculated and the Doppler frequency signature of the object is determined.

  6. Noise robustness of interferometric surface topography evaluation methods. Correlogram correlation

    Science.gov (United States)

    Kiselev, Ilia; Kiselev, Egor I.; Drexel, Michael; Hauptmannl, Michael

    2017-12-01

    Different surface height estimation methods are differently affected by interferometric noise. From a theoretical analysis we obtain height variance estimators for the methods. The estimations allow us to rigorously compare the noise robustness of popular evaluation algorithms. The envelope methods have the highest variances and hence the lowest noise resistances. The noise robustness improves from the envelope to the phase methods, but a technique involving the correlation of correlograms is superior even to the latter. We dwell on some details of this correlogram correlation method and the range of its application.

  7. Interferometric full-waveform inversion of time-lapse data

    KAUST Repository

    Sinha, Mrinal

    2017-08-17

    One of the key challenges associated with time-lapse surveys is ensuring the repeatability between the baseline and monitor surveys. Non-repeatability between the surveys is caused by varying environmental conditions over the course of different surveys. To overcome this challenge, we propose the use of interferometric full waveform inversion (IFWI) for inverting the velocity model from data recorded by baseline and monitor surveys. A known reflector is used as the reference reflector for IFWI, and the data are naturally redatumed to this reference reflector using natural reflections as the redatuming operator. This natural redatuming mitigates the artifacts introduced by the repeatability errors that originate above the reference reflector.

  8. Satellite SAR interferometric techniques applied to emergency mapping

    Science.gov (United States)

    Stefanova Vassileva, Magdalena; Riccardi, Paolo; Lecci, Daniele; Giulio Tonolo, Fabio; Boccardo Boccardo, Piero; Chiesa, Giuliana; Angeluccetti, Irene

    2017-04-01

    This paper aim to investigate the capabilities of the currently available SAR interferometric algorithms in the field of emergency mapping. Several tests have been performed exploiting the Copernicus Sentinel-1 data using the COTS software ENVI/SARscape 5.3. Emergency Mapping can be defined as "creation of maps, geo-information products and spatial analyses dedicated to providing situational awareness emergency management and immediate crisis information for response by means of extraction of reference (pre-event) and crisis (post-event) geographic information/data from satellite or aerial imagery". The conventional differential SAR interferometric technique (DInSAR) and the two currently available multi-temporal SAR interferometric approaches, i.e. Permanent Scatterer Interferometry (PSI) and Small BAseline Subset (SBAS), have been applied to provide crisis information useful for the emergency management activities. Depending on the considered Emergency Management phase, it may be distinguished between rapid mapping, i.e. fast provision of geospatial data regarding the area affected for the immediate emergency response, and monitoring mapping, i.e. detection of phenomena for risk prevention and mitigation activities. In order to evaluate the potential and limitations of the aforementioned SAR interferometric approaches for the specific rapid and monitoring mapping application, five main factors have been taken into account: crisis information extracted, input data required, processing time and expected accuracy. The results highlight that DInSAR has the capacity to delineate areas affected by large and sudden deformations and fulfills most of the immediate response requirements. The main limiting factor of interferometry is the availability of suitable SAR acquisition immediately after the event (e.g. Sentinel-1 mission characterized by 6-day revisiting time may not always satisfy the immediate emergency request). PSI and SBAS techniques are suitable to produce

  9. Next Generation X-Ray Optics: High-Resolution, Light-Weight, and Low-Cost

    Science.gov (United States)

    Zhang, William W.

    2012-01-01

    X-ray telescopes are essential to the future of x-ray astronomy. In this talk I will describe a comprehensive program to advance the technology for x-ray telescopes well beyond the state of the art represented by the three currently operating missions: Chandra, XMM-Newton, and Suzaku. This program will address the three key issues in making an x-ray telescope: (1) angular resolution, (2) effective area per unit mass, and (3) cost per unit effective area. The objectives of this technology program are (1) in the near term, to enable Explorer-class x-ray missions and an IXO-type mission, and (2) in the long term, to enable a flagship x-ray mission with sub-arcsecond angular resolution and multi-square-meter effective area, at an affordable cost. We pursue two approaches concurrently, emphasizing the first approach in the near term (2-5 years) and the second in the long term (4-10 years). The first approach is precision slumping of borosilicate glass sheets. By design and choice at the outset, this technique makes lightweight and low-cost mirrors. The development program will continue to improve angular resolution, to enable the production of 5-arcsecond x-ray telescopes, to support Explorer-class missions and one or more missions to supersede the original IXO mission. The second approach is precision polishing and light-weighting of single-crystal silicon mirrors. This approach benefits from two recent commercial developments: (1) the inexpensive and abundant availability of large blocks of monocrystalline silicon, and (2) revolutionary advances in deterministic, precision polishing of mirrors. By design and choice at the outset, this technique is capable of producing lightweight mirrors with sub-arcsecond angular resolution. The development program will increase the efficiency and reduce the cost of the polishing and the light-weighting processes, to enable the production of lightweight sub-arcsecond x-ray telescopes. Concurrent with the fabrication of lightweight

  10. Thermal wave imaging using lockin-interferometric methods

    Energy Technology Data Exchange (ETDEWEB)

    Menner, P; Gerhard, H; Busse, G, E-mail: Philipp.Menner@ikt.uni-stuttgart.d [Institute of Polymer Technology (IKT), - Non Destructive Testing (IKT-ZfP) -, University of Stuttgart, Pfaffenwaldring 32, D-70569 Stuttgart (Germany)

    2010-03-01

    We report about a technique where we transferred the Lockin-principle from Lockin-thermography to interferometry to perform thermal wave lockin-interferometry. This technique is based on speckle-interferometric imaging of periodical height changes going along with the temperature modulation in a thermal wave. We used both electronic speckle pattern interferometry and shearography setups and operated them with low frequency periodical heat deposition while a stack of interferometric fringe patterns was recorded. After unwrapping, each pixel of the stack was Fourier-analysed at the Lockin-frequency, giving an amplitude image and phase image of low frequency thermal deformation. Though this is very much like Lockin-thermography, the image generating mechanism is substantially different: The thermal wave generates periodical thermal expansion correlated with an overall deformation where the depth integral of the thermal wave is involved. At such a low frequency (below 1 Hz), deformation occurs simultaneously everywhere except in areas where thermal wave propagation is modified e.g. by boundaries, which affect the phase of deformation. Depth range is adjusted via modulation frequency as in lockin thermography.

  11. CHARACTERISTICS OF AIRBORNE INTERFEROMETRIC SYNTHETIC APERTURE RADAR WITH SECTOR SCAN

    Directory of Open Access Journals (Sweden)

    Evgenii E. Nechayev

    2017-01-01

    Full Text Available One of the drawbacks of airborne interferometric synthetic aperture radar is a relatively narrow swath compared to analogous space based systems. Increasing the swath with side view of the interferometer can be possible by increasing the flight altitude and angle of sight. At the same time the height measurement accuracy decreases due to slant range distance increase. Another possible way of swath increasing is using sector scan. The efficiency of sector scan using in interferometric synthetic aperture radar is analyzed in this paper. The mathematical model and geometry of height measurement at a sector scan have been discussed. There was made an analysis of the effect of terrain height and observation angle on received signal phase changing. Observation angle changing is shown to contribute to the phase changing. Potential height accuracy measurement was calculated. The calculation results show that increasing the observation angle reduces height accuracy measurement. The maximum accuracy decrease is obtained at the observation angle of 90°. Despite height accuracy measurement decrease applying the sector scan allow to expand the swath. The accuracy decrease can be limited by selecting optimal parameters of scanning.

  12. Super-virtual interferometric diffractions as guide stars

    KAUST Repository

    Dai, Wei

    2011-01-01

    A significant problem in seismic imaging is seismically seeing below salt structures: large velocity contrasts and the irregular geometry of the salt-sediment interface strongly defocus both the downgoing and upgoing seismic wavefields. This can result in severely defocused migration images so as to seismically render some subsalt reserves invisible. The potential cure is a good estimate of the subsalt and salt velocity distributions, but that is also the problem: severe velocity contrasts prevent the appearance of coherent subsalt reflections in the surface records so that MVA or tomographic methods can become ineffective. We now present an interferometric method for extracting the diffraction signals that emanate from diffractors, also denoted as seismic guide stars. The signal-to-noise ratio of these interferometric diffractions is enhanced by N, where N is the number of source points coincident with the receiver points. Thus, diffractions from subsalt guide stars can then be rendered visible and so can be used for velocity analysis, migration, and focusing of subsalt reflections. Both synthetic and field data records are used to demonstrate the benefits and limitations of this method. © 2011 Society of Exploration Geophysicists.

  13. Interferometric Synthetic Aperture Microscopy: Computed Imaging for Scanned Coherent Microscopy

    Directory of Open Access Journals (Sweden)

    Stephen A. Boppart

    2008-06-01

    Full Text Available Three-dimensional image formation in microscopy is greatly enhanced by the use of computed imaging techniques. In particular, Interferometric Synthetic Aperture Microscopy (ISAM allows the removal of out-of-focus blur in broadband, coherent microscopy. Earlier methods, such as optical coherence tomography (OCT, utilize interferometric ranging, but do not apply computed imaging methods and therefore must scan the focal depth to acquire extended volumetric images. ISAM removes the need to scan the focus by allowing volumetric image reconstruction from data collected at a single focal depth. ISAM signal processing techniques are similar to the Fourier migration methods of seismology and the Fourier reconstruction methods of Synthetic Aperture Radar (SAR. In this article ISAM is described and the close ties between ISAM and SAR are explored. ISAM and a simple strip-map SAR system are placed in a common mathematical framework and compared to OCT and radar respectively. This article is intended to serve as a review of ISAM, and will be especially useful to readers with a background in SAR.

  14. Interferometric and localized surface plasmon based fiber optic sensor

    Science.gov (United States)

    Muri, Harald Ian D. I.; Bano, Andon; Hjelme, Dag Roar

    2017-02-01

    We demonstrate a novel single point, multi-parameter, fiber optic sensor concept based on a combination of interferometric and plasmonic sensor modalities on an optical fiber end face. The sensor consists of a micro-Fabry-Perot interferometer in the form of a hemispherical stimuli-responsive hydrogel with immobilized gold nanoparticles. We present results of proof-of-concept experiments demonstrating local surface plasmon resonance (LSPR) sensing of refractive index (RI) in the visible range and interferometric measurements of volumetric changes of the pH stimuli-responsive hydrogel in near infrared range. The response of LSPR to RI (Δλr/ΔRI 877nm/RI) and the free spectral range (FSR) to pH (ΔpH/ΔFSR = 0.09624/nm) were measured with LSPR relatively constant for hydrogel swelling degree and FSR relatively constant for RI. We expect this novel sensor concept to be of great value for biosensors for medical applications.

  15. Interferometric measurement of a laser produced plasma using Nomarski interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Seong Y.; Hong, Youngjun; Ha, Sungyong; Kim, Heejin; Lim, Changhwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    It is important to understand its temporal and spatial dynamics for obtaining plasma conditions in each application. Laser interferometry tool has a capability for determining the spatial distribution of electron density at early stages of plume expansion. In this study, the interferometric analysis was carried out with the aim of investigating the characteristics of laser-induced plasma on the surface of titanium (Ti) metal target. We employed the Nomarski interferometry tool to obtain interference fringe patterns from the plasma. The Nomarski interferometry tool can be convenient approach to other common tools such as Michelson and Mach-Zehnder interferometers because it has intrinsic advantages of its compact size and easy alignment. Nomarski interferometry tool is based on the concept that the probe beam passing the laser-produced plasmas is divided by the bi-prism and recombined to generate interference patterns. The spatial and temporal behavior of laser-produced plasma was investigated on the basis of interferometric analysis using Nomarski interferometer. Electron density profile was calculated using Abel inversion equation via Fast Fourier-transformation method.

  16. Noninvasive encapsulated fiber optic probes for interferometric measurement

    Science.gov (United States)

    Zboril, O.; Cubik, J.; Kepak, S.; Nedoma, J.; Fajkus, M.; Zavodny, P.; Vasinek, V.

    2017-10-01

    This article focuses on the sensitivity of encapsulated interferometric probes. These probes are used mainly for BioMed and security applications. Fiber-optic sensors are interesting for these applications, as they are resistant to electromagnetic interference (EMI) and that also do not affect the surrounding medical and security equipment. Using a loop of the optical fiber with is not a suitable for these measurements. The optical fiber should be fixed to one position, and should not significantly bend. For these reasons, the optical fiber is encapsulated. Furthermore, it is necessary that the encapsulated measuring probes were flexible, inert, water resistant and not toxic. Fiber-optic sensors shouldn't be magnetically active, so they can be used for example, in magnetic resonance environments (MR). Probes meeting these requirements can be widely used in health care and security applications. Encapsulation of interferometric measuring arm brings changes in susceptibility of measurements in comparison with the optical fiber without encapsulation. To evaluate the properties of the encapsulated probes, series of probes made from different materials for encapsulation was generated, using two types of optical fibers with various degrees of protection. Comparison of the sensitivity of different encapsulated probes was performed using a series of measurements at various frequencies. The measurement results are statistically compared in the article and commented. Given the desired properties polydimethylsiloxane (PDMS) polymer has been proven the most interesting encapsulating material for further research.

  17. Secure space-to-space interferometric communications and its nexus to the physics of quantum entanglement

    Science.gov (United States)

    Duarte, F. J.

    2016-12-01

    The history of the probability amplitude equation | ψ > = ( | x , y > - | y , x > ) applicable to quanta pairs, propagating in different directions with entangled polarizations, is reviewed and traced back to the 1947-1949 period. The interferometric Dirac foundations common to | ψ > = ( | x , y > - | y , x > ) and the generalized N-slit interferometric equation, for indistinguishable quanta, are also described. The results from a series of experiments on N-slit laser interferometers, with intra interferometric propagation paths up to 527 m, are reviewed. Particular attention is given to explain the generation of interferometric characters, for secure space-to-space communications, which immediately collapse on attempts of interception. The design of a low divergence N-slit laser interferometer for low Earth orbit-low Earth orbit (LEO-LEO), and LEO-geostationary Earth orbit (LEO-GEO), secure interferometric communications is described and a weight assessment is provided.

  18. Non-convex optimization for self-calibration of direction-dependent effects in radio interferometric imaging

    Science.gov (United States)

    Repetti, Audrey; Birdi, Jasleen; Dabbech, Arwa; Wiaux, Yves

    2017-10-01

    Radio interferometric imaging aims to estimate an unknown sky intensity image from degraded observations, acquired through an antenna array. In the theoretical case of a perfectly calibrated array, it has been shown that solving the corresponding imaging problem by iterative algorithms based on convex optimization and compressive sensing theory can be competitive with classical algorithms such as clean. However, in practice, antenna-based gains are unknown and have to be calibrated. Future radio telescopes, such as the Square Kilometre Array, aim at improving imaging resolution and sensitivity by orders of magnitude. At this precision level, the direction-dependency of the gains must be accounted for, and radio interferometric imaging can be understood as a blind deconvolution problem. In this context, the underlying minimization problem is non-convex, and adapted techniques have to be designed. In this work, leveraging recent developments in non-convex optimization, we propose the first joint calibration and imaging method in radio interferometry, with proven convergence guarantees. Our approach, based on a block-coordinate forward-backward algorithm, jointly accounts for visibilities and suitable priors on both the image and the direction-dependent effects (DDEs). As demonstrated in recent works, sparsity remains the prior of choice for the image, while DDEs are modelled as smooth functions of the sky, I.e. spatially band-limited. Finally, we show through simulations the efficiency of our method, for the reconstruction of both images of point sources and complex extended sources. matlab code is available on GitHub.

  19. First Results of the Performance of the Global Forest/Non-Forest Map derived from TanDEM-X Interferometric Data

    Science.gov (United States)

    Gonzalez, Carolina; Rizzoli, Paola; Martone, Michele; Wecklich, Christopher; Bueso Bello, Jose Luis; Krieger, Gerhard; Zink, Manfred

    2017-04-01

    The globally acquired interferometric synthetic aperture radar (SAR) data set, used for the recently completed primary goal of the TanDEM-X mission, enables a big opportunity for scientific geo-applications. Of great importance for land characterization, classification, and monitoring is that the data set is globally acquired without gaps and includes multiple acquisitions of every region, with comparable parameters. One of the most valuable maps that can be derived from interferometric SAR data for land classification describes the presence/absence of vegetation. In particular, here we report about the deployment of the Global Forest/Non-Forest Map, derived from TanDEM-X interferometric SAR quick-look data, at a ground resolution of 50 m by 50 m. Presence of structures and in particular vegetation produces multiple scattering known as volume decorrelation. Its contribution can be directly estimated from the assessment of coherence loss in the interferometric bistatic pair, by compensating for all other decorrelation sources, such as poor signal-to-noise ratio or quantization noise. Three different forest types have been characterized based on the estimated volume decorrelation: tropical, temperate, and boreal forest. This characterization was then used in a fuzzy clustering approach for the discrimination of vegetated areas on a global scale. Water and cities are filtered out from the generated maps in order to distinguish volume decorrelation from other decorrelation sources. The validation and performance comparison of the delivered product is also presented, and represents a fundamental tool for optimizing the whole algorithm at all different stages. Furtheremore, as the time interval of the acquisitions is almost 4 years, change detection can be performed as well and examples of deforestation are also going to be included in the final paper.

  20. An optical fiber interferometric system for non-contact measurement of atmospheric optical turbulence

    Science.gov (United States)

    Mei, Haiping; Rao, Ruizhong

    2006-02-01

    Optical turbulence degrades the quality of laser beam propagation and the quality of the image of optical system, limiting the spatial resolution that can be obtained. A novel single-air-gap fiber optical interferometric system useful for non-contact measurement of the fine structure of optical turbulence is presented. The main idea of this system is based on the application of a specially constructed optical fiber Mach-Zehnder interferometer to measure the phase fluctuations effected by the random fluctuations of refractive index in the turbulent atmosphere. The light source is a long coherence length infrared laser operating at the wavelength of 1.31μm and the optical path exposed to the atmosphere can be adjusted to a most suitable value according to the operational environment. Theoretical estimation illustrates that the system can measure the minimal atmospheric refractive index fluctuation up to 10 -10 during a 2cm propagation path. It is easy to have a calibration of the system and the result shows that the voltage refractive index sensitivity is about 2.1x10 -6 V -1. The system is integrated and well fixed in a burly airproof box with only the sensing arm exposed to the air. It follows that the system is suitable for the measurement of atmospheric turbulence over land and ocean surfaces.

  1. Interferometric analysis of laser-driven cylindrically focusing shock waves in a thin liquid layer.

    Science.gov (United States)

    Veysset, David; Мaznev, Alexei A; Pezeril, Thomas; Kooi, Steven; Nelson, Keith A

    2016-12-23

    Shock waves in condensed matter are of great importance for many areas of science and technology ranging from inertially confined fusion to planetary science and medicine. In laboratory studies of shock waves, there is a need in developing diagnostic techniques capable of measuring parameters of materials under shock with high spatial resolution. Here, time-resolved interferometric imaging is used to study laser-driven focusing shock waves in a thin liquid layer in an all-optical experiment. Shock waves are generated in a 10 µm-thick layer of water by focusing intense picosecond laser pulses into a ring of 95 µm radius. Using a Mach-Zehnder interferometer and time-delayed femtosecond laser pulses, we obtain a series of images tracing the shock wave as it converges at the center of the ring before reemerging as a diverging shock, resulting in the formation of a cavitation bubble. Through quantitative analysis of the interferograms, density profiles of shocked samples are extracted. The experimental geometry used in our study opens prospects for spatially resolved spectroscopic studies of materials under shock compression.

  2. Measurement and Mitigation of the Ionosphere in L-Band Interferometric SAR Data

    Science.gov (United States)

    Rosen, Paul A.; Hensley, Scott; Chen, Curtis

    2010-01-01

    Satellite-based repeat-pass Interferometric Synthetic Aperture Radar (InSAR) provides a synoptic high spatial resolution perspective of Earth's changing surface, permitting one to view large areas quickly and efficiently. By measuring relative phase change from one observation to the next on a pixel-by-pixel basis, maps of deformation and change can be derived. Variability of the atmosphere and the ionosphere leads to phase/time delays that are present in the data that can mask many of the subtle deformation signatures of interest, so methods for mitigation of these effects are important. Many of these effects have been observed in existing ALOS PALSAR data, and studies are underway to characterize and mitigate the ionosphere using these data. Since the ionosphere is a dispersive medium, it is possible in principle distinguish the ionospheric signatures from the non-dispersive effects of deformation and the atmosphere. In this paper, we describe a method for mapping the ionosphere in InSAR data based on a multi-frequency split-spectrum processing technique.

  3. Coherent change detection and interferometric ISAR measurements in the folded compact range

    Energy Technology Data Exchange (ETDEWEB)

    Sorensen, K.W.

    1996-08-01

    A folded compact range configuration has been developed ant the Sandia National Laboratories` compact range antenna and radar-cross- section measurement facility as a means of performing indoor, environmentally-controlled, far-field simulations of synthetic aperture radar (SAR) measurements of distributed target samples (i.e. gravel, sand, etc.). The folded compact range configuration has previously been used to perform coherent-change-detection (CCD) measurements, which allow disturbances to distributed targets on the order of fractions of a wavelength to be detected. This report describes follow-on CCD measurements of other distributed target samples, and also investigates the sensitivity of the CCD measurement process to changes in the relative spatial location of the SAR sensor between observations of the target. Additionally, this report describes the theoretical and practical aspects of performing interferometric inverse-synthetic-aperture-radar (IFISAR) measurements in the folded compact range environment. IFISAR measurements provide resolution of the relative heights of targets with accuracies on the order of a wavelength. Several examples are given of digital height maps that have been generated from measurements performed at the folded compact range facility.

  4. Radio-interferometric Neutrino Reconstruction for the Askaryan Radio Array

    Directory of Open Access Journals (Sweden)

    Lu Ming-Yuan

    2017-01-01

    Full Text Available The Askaryan Radio Array (ARA is a neutrino telescope array under phased deployment near the South Pole. The array aims to discover and determine the ultra-high energy neutrino flux via detection of the Askaryan signal from neutrino-induced showers. This novel detection channel makes ARA the most cost-effective neutrino observatory in probing the neutrino flux from 1017eV – 1019eV. This contribution will discuss an interferometric vertex reconstruction technique developed for ARA, taking into account the curved paths traveled by EM radiation in inhomogeneous ice. Preliminary results on the directional reconstruction of an in situ calibration pulser as well as simulated neutrino vertices will be presented.

  5. INTERFEROMETRIC SYNTHETIC APERTURE RADAR (INSAR TECHNOLOGY AND GEOMORPHOLOGY INTERPRETATION

    Directory of Open Access Journals (Sweden)

    M. Maghsoudi

    2013-09-01

    Full Text Available Geomorphology is briefly the study of landforms and their formative processes on the surface of the planet earth as human habitat. The landforms evolution and the formative processes can best be studied by technologies with main application in study of elevation. Interferometric Synthetic Aperture Radar (InSAR is the appropriate technology for this application. With phase differences calculations in radar waves, the results of this technology can extensively be interpreted for geomorphologic researches. The purpose of the study is to review the geomorphologic studies using InSAR and also the technical studies about InSAR with geomorphologic interpretations. This study states that the InSAR technology can be recommended to be employed as a fundamental for geomorphology researches.

  6. Graphene-oxide-coated interferometric optical microfiber ethanol vapor sensor.

    Science.gov (United States)

    Zhang, Jingle; Fu, Haiwei; Ding, Jijun; Zhang, Min; Zhu, Yi

    2017-11-01

    A graphene-oxide-coated interferometric microfiber-sensor-based polarization-maintaining optical fiber is proposed for highly sensitive detecting for ethanol vapor concentration at room temperature in this paper. The strong sensing capability of the sensor to detect the concentration of ethanol vapor is demonstrated, taking advantage of the evanescent field enhancement and gas absorption of a graphene-oxide-coated microfiber. The transmission spectrum of the sensor varies with concentrations of ethanol vapor, and the redshift of the transmission spectrum has been analyzed for the concentration range from 0 to 80 ppm with sensitivity as high as 0.138 nm/ppm. The coated graphene oxide layer induces the evanescent field enhancement and gas selective adsorption, which improves sensitivity and selectivity of the microfiber gas sensor for ethanol vapor detection.

  7. Interferometric control of the photon-number distribution

    Directory of Open Access Journals (Sweden)

    H. Esat Kondakci

    2017-07-01

    Full Text Available We demonstrate deterministic control over the photon-number distribution by interfering two coherent beams within a disordered photonic lattice. By sweeping a relative phase between two equal-amplitude coherent fields with Poissonian statistics that excite adjacent sites in a lattice endowed with disorder-immune chiral symmetry, we measure an output photon-number distribution that changes periodically between super-thermal and sub-thermal photon statistics upon ensemble averaging. Thus, the photon-bunching level is controlled interferometrically at a fixed mean photon-number by gradually activating the excitation symmetry of the chiral-mode pairs with structured coherent illumination and without modifying the disorder level of the random system itself.

  8. Biomolecular detection with an interferometric microfiber-capillary optofluidic sensor

    Science.gov (United States)

    Liang, Lili; Jin, Long; Guan, Bai-Ou

    2017-04-01

    We have developed a chip-scale optofluidic sensor for biomolecular detection, by tapering laterally aligned silica microfiber and capillary to form a modal interferometer. With the pre-immobilization of DNA probes, the sensor is capable of selectively detecting single-stranded microRNA-let7a (molecular weight: 6.5 k) by measuring the spectral shift of the interferometric spectrum. A log-linear response from 2 nM to 20 μM and a minimum detectable concentration of 212 pM (1.43 ng/mL) have been achieved. The sensor is promising for future diagnosis applications due to its high sensitivity, resistance to environmental perturbations, improved portability, and intrinsic connection to fiber optic measurement.

  9. Interferometric readout of a monolithic accelerometer, towards the fm/√Hz resolution

    NARCIS (Netherlands)

    van Heijningen, J. V.; Bertolini, A.; Van Den Brand, J. F J

    2016-01-01

    The European Gravitational wave Observatory Virgo is undergoing an upgrade to increase its strain sensitivity to about 3×10-241/√Hz in the detection band of 10 Hz-10 kHz. The upgrade for this detector necessitates seismically isolating sensing optics in a vacuum environment that were on an optical

  10. Picometer resolution interferometric characterization of the dimensional stability of zero CTE CFRP

    Science.gov (United States)

    Cordero Machado, Jorge; Heinrich, Thomas; Schuldt, Thilo; Gohlke, Martin; Lucarelli, Stefano; Weise, Dennis; Johann, Ulrich; Peters, Achim; Braxmaier, Claus

    2008-07-01

    Highly stable but lightweight structural materials are essential for the realization of spaceborne optical instruments, for example telescopes. In terms of optical performance, usually tight tolerances on the absolute spacing between telescope mirrors have to be maintained from integration on ground to operation in final orbit. Furthermore, a certain stability of the telescope structure must typically be ensured in the measurement band. Particular challenging requirements have to be met for the LISA Mission (Laser Interferometer Space Antenna), where the spacing between primary and secondary mirror must be stable to a few picometers. Only few materials offer sufficient thermal stability to provide such performance. Candidates are for example Zerodur and Carbon-Fiber Reinforced Plastic (CFRP), where the latter is preferred in terms of mechanical stiffness and robustness. We are currently investigating the suitability of CFRP with respect to the LISA requirements by characterization of its dimensional stability with heterodyne laser interferometry. The special, highly symmetric interferometer setup offers a noise level of 2 pm/√Hz at 0.1Hz and above, and therefore represents a unique tool for this purpose. Various procedures for the determination of the coefficient of thermal expansion (CTE) have been investigated, both on a test sample with negative CTE, as well as on a CFRP tube specifically tuned to provide a theoretical zero expansion in the axial dimension.

  11. Differential group refractive index dispersion of glasses of optical fibres measured by a white-light spectral interferometric technique

    Science.gov (United States)

    Hlubina, Petr; Chlebus, Radek; Ciprian, Dalibor

    2007-05-01

    We report on a white-light interferometric technique employing a low-resolution spectrometer to measure the differential group refractive index of glasses of optical fibres over a wide wavelength range. The technique utilizes an unbalanced Mach-Zehnder interferometer with a fibre under test of known length inserted in one of the interferometer arms and the other arm with adjustable path length. We record a series of spectral interferograms to measure the equalization wavelength as a function of the path length difference, or equivalently the group dispersion. Subtracting the group dispersion of the optical components present in the interferometer along with the fibre, we measure the wavelength dependence of differential group refractive index for pure silica and SK222 glasses. We confirm that the differential group dispersion measured for pure silica glass agrees well with that described by the dispersion equation.

  12. The Space Infrared Interferometric Telescope (SPIRIT): The Mission Design Solution Space and the Art of the Possible

    Science.gov (United States)

    Leisawitz, David; Hyde, T. Tupper; Rinehart, Stephen A.; Weiss, Michael

    2008-01-01

    Although the Space Infrared Interferometric Telescope (SPIRIT) was studied as a candidate NASA Origins Probe mission, the real world presents a broader set of options, pressures, and constraints. Fundamentally, SPIRIT is a far-IR observatory for high-resolution imaging and spectroscopy designed to address a variety of compelling scientific questions. How do planetary systems form from protostellar disks, dousing some planets in water while leaving others dry? Where do planets form, and why are some ice giants while others are rocky? How did high-redshift galaxies form and merge to form the present-day population of galaxies? This paper takes a pragmatic look at the mission design solution space for SPIRIT, presents Probe-class and facility-class mission scenarios, and describes optional design changes. The costs and benefits of various mission design alternatives are roughly evaluated, giving a basis for further study and to serve as guidance to policy makers.

  13. Reservoir monitoring and characterization using satellite geodetic data: Interferometric Synthetic Aperture Radar observations from the Krechba field, Algeria

    Energy Technology Data Exchange (ETDEWEB)

    Vasco, D.W.; Ferretti, Alessandro; Novali, Fabrizio

    2008-05-01

    Deformation in the material overlying an active reservoir is used to monitor pressure change at depth. A sequence of pressure field estimates, eleven in all, allow us to construct a measure of diffusive travel time throughout the reservoir. The dense distribution of travel time values means that we can construct an exactly linear inverse problem for reservoir flow properties. Application to Interferometric Synthetic Aperture Radar (InSAR) data gathered over a CO{sub 2} injection in Algeria reveals pressure propagation along two northwest trending corridors. An inversion of the travel times indicates the existence of two northwest-trending high permeability zones. The high permeability features trend in the same direction as the regional fault and fracture zones. Model parameter resolution estimates indicate that the features are well resolved.

  14. Novel Fibre Optic-Based Interferometric Sensors Exploiting Coherent and Low-Coherence Signal Processing Techniques.

    Science.gov (United States)

    Gerges, Awad Samir

    Available from UMI in association with The British Library. The work presented in this thesis is concerned with the introduction of several novel fibre-optic-based interferometric sensors. The main objectives have been to design practical sensors which are remote, passive, insensitive to environmental perturbations and capable of reinitialisation when it is switched on. A sensor for temperature or strain measurement is demonstrated using a short coherence length light source. A novel signal processing technique, based on either tracking the point of maximum visibility (zero path imbalance) or the first quadrature point, has been introduced. The advantages of both techniques are that the value of the measurand can be recovered when the sensor is 'powered up' and the accuracy of the sensor is nearly independent of drift in the source wavelength. The potential of using multi-mode laser diodes, as alternatives to the low coherence-length sources such as LED's or SLD's commonly used in 'white light' fibre-optic interferometric sensors has been studied. It is shown that the main advantage gained in using such sources is improved resolution due to the significant increase in the launched optical power. The use of such sources however is subject to certain restrictions. A novel form of sensor in which the sensing element is a miniature hemispherical air cavity Fabry Perot interferometer has been introduced. The properties of the cavity are theoretically studied and then verified experimentally. This new cavity design has been exploited for two different types of thermometers. A novel accelerometer, in which the sensing element is a weighted diaphragm, has also been introduced. The displacement of the diaphragm produced by acceleration is measured using a similar miniature hemispherical air -spaced Fabry-Perot interferometer, of which one mirror is mounted on the diaphragm. The design of the accelerometer has been developed to have minimal sensitivity to environmental and

  15. In situ calibration of an interferometric velocity sensor for measuring small scale flow structures using a Talbot-pattern

    Science.gov (United States)

    König, Jörg; Czarske, Jürgen

    2017-10-01

    Small scale flow phenomena play an important role across engineering, biological and chemical sciences. To gain deeper understanding of the influence of those flow phenomena involved, measurement techniques with high spatial resolution are often required, presuming a calibration of very low uncertainty. To enable such measurements, a method for the in situ calibration of an interferometric flow velocity profile sensor is presented. This sensor, with demonstrated spatial resolution better than 1 μm, allows for spatially-resolving measurements with low velocity uncertainty in flows with high velocity gradients, on condition that the spatial behavior of the interference fringe systems is well-known by calibration with low uncertainty, especially challenging to obtain at applications with geometries difficult to access. The calibration method described herein uses three interfering beams to form the interference fringe systems of the sensor, yielding Doppler burst signals exhibiting two peaks in the frequency domain whose amplitude ratio varies periodically along the measurement volume major z-axis, giving a further independent value of the axial tracer particle position that can be used to determine the calibration functions of the sensor during the flow measurement. A flow measurement in a microchannel experimentally validates that the presented approach allows for simultaneously estimating the calibration functions and the velocity profile, providing flow measurements with very low systematic measurement errors of the particle position of less than 400 nm (confidence interval 95%). In that way, the interferometric flow velocity profile sensor utilizing the in situ self-calibration method promises valuable insights on small scale flow phenomena, such as those given in shear and boundary layer flows, by featuring reliable flow measurements due to minimum systematic and statistical measurement errors.

  16. Monitoring forest carbon in a Tanzanian woodland using interferometric SAR: a novel methodology for REDD

    National Research Council Canada - National Science Library

    Solberg, Svein; Gizachew, Belachew; Næsset, Erik; Gobakken, Terje; Bollandsås, Ole Martin; Mauya, Ernest William; Olsson, Håkan; Malimbwi, Rogers; Zahabu, Eliakimu

    2015-01-01

    ... as a basis for a reference emission level. Working in a miombo woodland in Tanzania, we here aim at demonstrating a novel 3D satellite approach based on interferometric processing of radar imagery (InSAR...

  17. Ultra-Low Noise Quad Photoreceiver for Space Based Laser Interferometric Gravity Wave Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Gravity wave detection using space-based long-baseline laser interferometric sensors imposes stringent noise requirements on the system components, including the...

  18. Sculpting the disk around T Chamaeleontis: an interferometric view

    Science.gov (United States)

    Olofsson, J.; Benisty, M.; Le Bouquin, J.-B.; Berger, J.-P.; Lacour, S.; Ménard, F.; Henning, Th.; Crida, A.; Burtscher, L.; Meeus, G.; Ratzka, T.; Pinte, C.; Augereau, J.-C.; Malbet, F.; Lazareff, B.; Traub, W.

    2013-04-01

    Context. Circumstellar disks are believed to be the birthplace of planets and are expected to dissipate on a timescale of a few Myr. The processes responsible for the removal of the dust and gas will strongly modify the radial distribution of the circumstellar matter and consequently the spectral energy distribution. In particular, a young planet will open a gap, resulting in an inner disk dominating the near-IR emission and an outer disk emitting mostly in the far-infrared. Aims: We analyze a full set of data involving new near-infrared data obtained with the 4-telescope combiner (VLTI/PIONIER), new mid-infrared interferometric VLTI/MIDI data, literature photometric and archival data from VLT/NaCo/SAM to constrain the structure of the transition disk around T Cha. Methods: After a preliminary analysis with a simple geometric model, we used the MCFOST radiative transfer code to simultaneously model the SED and the interferometric observables from raytraced images in the H-, L'-, and N-bands. Results: We find that the dust responsible for the strong emission in excess in the near-IR must have a narrow temperature distribution with a maximum close to the silicate sublimation temperature. This translates into a narrow inner dusty disk (0.07-0.11 AU), with a significant height (H/r ~ 0.2) to increase the geometric surface illuminated by the central star. We find that the outer disk starts at about 12 AU and is partially resolved by the PIONIER, SAM, and MIDI instruments. We discuss the possibility of a self-shadowed inner disk, which can extend to distances of several AU. Finally, we show that the SAM closure phases, interpreted as the signature of a candidate companion, may actually trace the asymmetry generated by forward scattering by dust grains in the upper layers of the outer disk. These observations help constrain the inclination and position angle of the disk to about + 58° and - 70°, respectively. Conclusions: The circumstellar environment of T Cha appears

  19. STATISTICAL CHARACTERISTICS INVESTIGATION OF PREDICTION ERRORS FOR INTERFEROMETRIC SIGNAL IN THE ALGORITHM OF NONLINEAR KALMAN FILTERING

    Directory of Open Access Journals (Sweden)

    E. L. Dmitrieva

    2016-05-01

    Full Text Available Basic peculiarities of nonlinear Kalman filtering algorithm applied to processing of interferometric signals are considered. Analytical estimates determining statistical characteristics of signal values prediction errors were obtained and analysis of errors histograms taking into account variations of different parameters of interferometric signal was carried out. Modeling of the signal prediction procedure with known fixed parameters and variable parameters of signal in the algorithm of nonlinear Kalman filtering was performed. Numerical estimates of prediction errors for interferometric signal values were obtained by formation and analysis of the errors histograms under the influence of additive noise and random variations of amplitude and frequency of interferometric signal. Nonlinear Kalman filter is shown to provide processing of signals with randomly variable parameters, however, it does not take into account directly the linearization error of harmonic function representing interferometric signal that is a filtering error source. The main drawback of the linear prediction consists in non-Gaussian statistics of prediction errors including cases of random deviations of signal amplitude and/or frequency. When implementing stochastic filtering of interferometric signals, it is reasonable to use prediction procedures based on local statistics of a signal and its parameters taken into account.

  20. The Information Content of Interferometric Synthetic Aperture Radar: Vegetation and Underlying Surface Topography

    Science.gov (United States)

    Treuhaft, Robert N.

    1996-01-01

    This paper first gives a heuristic description of the sensitivity of Interferometric Synthetic Aperture Radar to vertical vegetation distributions and underlying surface topography. A parameter estimation scenario is then described in which the Interferometric Synthetic Aperture Radar cross-correlation amplitude and phase are the observations from which vegetation and surface topographic parameters are estimated. It is shown that, even in the homogeneous-layer model of the vegetation, the number of parameters needed to describe the vegetation and underlying topography exceeds the number of Interferometric Synthetic Aperture Radar observations for single-baseline, single-frequency, single-incidence-angle, single-polarization Interferometric Synthetic Aperture Radar. Using ancillary ground-truth data to compensate for the underdetermination of the parameters, forest depths are estimated from the INSAR data. A recently-analyzed multibaseline data set is also discussed and the potential for stand-alone Interferometric Synthetic Aperture Radar parameter estimation is assessed. The potential of combining the information content of Interferometric Synthetic Aperture Radar with that of infrared/optical remote sensing data is briefly discussed.

  1. Spectral interferometric fiber optic temperature sensor with enhanced sensitivity

    Science.gov (United States)

    Militky, J.; Kadulova, M.; Hlubina, P.

    2016-12-01

    Spectral interferometric techniques utilizing the interference of polarization modes in a highly birefringent (HB) elliptical-core fiber to measure temperature are analyzed experimentally. First, an experimental setup comprising a white-light source, a polarizer, a sensing birefringent fiber, an analyzer and a spectrometer is considered. Temperature sensing by this method is based on the wavelength interrogation. Second, the above setup is extended by a birefringent quartz crystal to increase the sensitivity of the temperature sensing. Third, the above setup is extended by an analyzer, and the combination of a polarizer, a birefringent quartz crystal and an analyzer represents another interferometer, which is used to increase the sensitivity of the temperature sensing. In this case the Vernier effect is present and the resultant spectrum is with an envelope, which is utilized in temperature sensing. We reached a sensitivity of 0.56 nm/K in the third setup, compared to -0.12 nm/K and -0.19 nm/K in the first and the second setup, respectively.

  2. Interferometric measurement of the angular velocity of moving humans

    Science.gov (United States)

    Nanzer, Jeffrey A.

    2012-06-01

    This paper presents an analysis of the measurement of the angular velocity of walking humans using a millimeter-wave correlation interferometer. Measurement of the angular velocity of moving objects is a desirable function in remote sensing applications. Doppler radar sensors are able to measure the signature of moving humans based on micro-Doppler analysis; however, a person moving with little to no radial velocity produces negligible Doppler returns. Measurement of the angular movement of humans can be done with traditional radar techniques, however the process involves either continuous tracking with narrow beamwidth or angle-of-arrival estimation algorithms. A new method of measuring the angular velocity of moving objects using interferometry has recently been developed which measures the angular velocity of an object without tracking or complex processing. The frequency of the interferometer signal response is proportional to the angular velocity of the object as it passes through the interferometer beam pattern. In this paper, the theory of the interferometric measurement of angular velocity is covered and simulations of the response of a walking human are presented. Simulations are produced using a model of a walking human to show the significant features associated with the interferometer response, which may be used in classification algorithms.

  3. Experimental demonstration of interferometric imaging using photonic integrated circuits.

    Science.gov (United States)

    Su, Tiehui; Scott, Ryan P; Ogden, Chad; Thurman, Samuel T; Kendrick, Richard L; Duncan, Alan; Yu, Runxiang; Yoo, S J B

    2017-05-29

    This paper reports design, fabrication, and demonstration of a silica photonic integrated circuit (PIC) capable of conducting interferometric imaging with multiple baselines around λ = 1550 nm. The PIC consists of four sets of five waveguides (total of twenty waveguides), each leading to a three-band spectrometer (total of sixty waveguides), after which a tunable Mach-Zehnder interferometer (MZI) constructs interferograms from each pair of the waveguides. A total of thirty sets of interferograms (ten pairs of three spectral bands) is collected by the detector array at the output of the PIC. The optical path difference (OPD) of each interferometer baseline is kept to within 1 µm to maximize the visibility of the interference measurement. We constructed an experiment to utilize the two baselines for complex visibility measurement on a point source and a variable width slit. We used the point source to demonstrate near unity value of the PIC instrumental visibility, and used the variable slit to demonstrate visibility measurement for a simple extended object. The experimental result demonstrates the visibility of baseline 5 and 20 mm for a slit width of 0 to 500 µm in good agreement with theoretical predictions.

  4. Interferometric Observations of the Cepheid ζ Geminorum with FLUOR / IOTA

    Science.gov (United States)

    Kervella, P.; Coudé du Foresto, V.; Traub, W. A.; Lacasse, M. G.

    The classical galactic cepheid zeta Gem has the largest angular diameter of all the northern classical cepheids, making it a very desirable target for interferometric observations. We used the IOTA interferometer and the FLUOR beam combiner to observe this star in late March 1999 over a four nights period. A variation of the angular diameter was detected at the 2 sigma level, allowing us to measure a uniform disk diameter of 2.15 mas +/-0.10 and a pulsation amplitude over the period of 0.38 mas +/-0.20. Based on previous Baade-Wesselink radius estimations of Zeta Gem, our measurements provide a distance of 299 pc +41/-33, in good agreement with the Hipparcos value of 358 pc +149/-81. Very high accuracy (0.5 %) visibility measurements enabled us to derive diameters with 8 % error bars despite a relatively short baseline of 38 m, which hardly resolves the star (mean visibility of 96 %). These observations open new possibilities for distance determination of pulsating stars by combining radial velocity and interferometry measurements. ESO's VLT Interferometer, with 200 m baseline and increased sensitivity will provide angular diameter estimations for hundreds of galactic cepheids at down to 0.1 % precision, and direct distance measurements based on the pulsation amplitude at 1 % precision.

  5. Absolute interferometric distance measurement using a FM-demodulation technique

    Science.gov (United States)

    Fischer, Edgar; Dalhoff, Ernst; Heim, Silke; Hofbauer, Ulrich; Tiziani, Hans J.

    1995-09-01

    We propose an interferometric method for measuring absolute distances larger than the wavelength. A laser diode is used as a light source. The principle of operation is based on multiple-wavelength interferometry that uses a modulated light source. This method uses the fact that the wavelength of light emitted by the laser diode can be varied by means of the injection current. The modulation of the injection current in combination with the optical heterodyne technique causes a high-frequency phase-modulated detector signal. The phase deviation of the signal is a measure of the optical path difference in the interferometer. By FM demodulation of the detector output with a phase-locked loop demodulator, the optical path difference can be determined directly without the classical ambiguity problem of interferometry. The measuring range in the experiments was limited to 50 mm by the maximum travel range of the used specimen translation stage. Because of the inherent light sensitivity of the method described, the rangefinder can be used for three-dimensional profile measurements on a wide variety of objects, even on diffuse scattering surfaces.

  6. Code-modulated interferometric imaging system using phased arrays

    Science.gov (United States)

    Chauhan, Vikas; Greene, Kevin; Floyd, Brian

    2016-05-01

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

  7. Super-Virtual Refraction Interferometric Redatuming: Enhancing the Refracted Energy

    KAUST Repository

    Aldawood, Ali

    2012-02-26

    onshore seismic data processing. Refraction tomography is becoming a common way to estimate an accurate near surface velocity model. One of the problems with refraction tomography is the low signal to noise ration in far offset data. To improve, we propose using super-virtual refraction interferometry to enhance the weak energy at far offsets. We use Interferometric Green\\'s functions to redatum sources by cross-correlating two traces recorded at receiver stations, A and B, from a source at location W. The result is a redatumed trace with a virtual source at A and a receiver at B, which can also be obtained by correlating two traces recorded at A and B from different shots. Stacking them would enhance the signal-to-noise ratio of this "virtual" trace. We next augment redatuming with convolution and stacking. The trace recorded at B from a virtual source at A is convolved with the original trace recorded at A from a source at W. The result is a "super-virtual" trace at B in the far-offset from a source at W. Stacking N traces gives a vN-improvement. We applied our method to noisy synthetic and field data recorded over a complex near-surface and we could pick more traces at far offsets. It was possible to accommodate more picks resulting in a better subsurface coverage

  8. Individual sperm selection by microfluidics integrated with interferometric phase microscopy.

    Science.gov (United States)

    Eravuchira, Pinkie J; Mirsky, Simcha K; Barnea, Itay; Levi, Mattan; Balberg, Michal; Shaked, Natan T

    2017-09-27

    The selection of sperm cells possessing normal morphology and motility is crucial for many assisted reproductive technologies (ART), especially for intracytoplasmic sperm injection (ICSI), as sperm quality directly affects the probability of inducing healthy pregnancy. We present a novel platform for real-time quantitative analysis and selection of individual sperm cells without staining. Towards this end, we developed an integrated approach, combining interferometric phase microscopy (IPM), for stain-free sperm imaging and real-time automatic analysis based on the sperm cell 3D morphology and contents, with a disposable microfluidic device, for sperm selection and enrichment. On testing the capabilities of the microfluidic device, we obtained successful selection of sperm cells with a selectivity of 89.5±3.5%, with no negative-decision sperm cells being inadvertently selected. In addition, we demonstrate the accuracy of sperm cell analysis using IPM by comparing the quantitative analysis produced by our IPM-based algorithm to the qualitative visual analysis performed independently by an experienced embryologist, which resulted in precision and specificity of 100%. We believe that the presented integrated approach has the potential to dramatically change the way sperm cells are selected for ICSI and other ART procedures, making the selection process more objective, quantitative and automatic, and thereby increasing success rates. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Multiplexed interferometric displacement sensing below the laser frequency noise limit

    Science.gov (United States)

    Lam, Timothy T.; Wuchenich, Danielle M. R.; Chow, Jong H.; McClelland, David E.; Shaddock, Daniel A.

    2011-05-01

    The resolution of fiber optic interferometry sensors is often limited by frequency noise in the laser. For this reason, prestabilization techniques have been used to reduce laser frequency fluctuations and improve signal resolution. However, for multi-element systems this becomes cumbersome and difficult to implement. In this paper, we demonstrate the use of digitally-enhanced interferometry for the interrogation of a multi-element sensing system. Over 50 dB of cross-talk rejection was found, with displacement resolutions of ~ 100 pm. Furthermore, using this technique, sub-frequency noise displacement resolution was obtained without the need for high performance sensors.

  10. Narrow head-tail radio galaxies at very high resolution

    Science.gov (United States)

    Terni de Gregory, B.; Feretti, L.; Giovannini, G.; Govoni, F.; Murgia, M.; Perley, R. A.; Vacca, V.

    2017-12-01

    Aims: Narrow-angle tailed (NAT) sources in clusters of galaxies can show on the large scale very narrow tails that are unresolved even at arcsecond resolution. These sources could therefore be classified as one-sided jets. The aim of this paper is to gain new insight into the structure of these sources, and establish whether they are genuine one-sided objects, or if they are two-sided sources. Methods: We observed a sample of apparently one-sided NAT sources at subarcsecond resolution to obtain detailed information on their structure in the nuclear regions of radio galaxies. Results: Most radio galaxies are found to show two-sided jets with sharp bends, and therefore the sources are similar to the more classical NATs, which are affected by strong projection effects. The reduced images (FITS) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/608/A58

  11. GRAVITY Spectro-interferometric Study of the Massive Multiple Stellar System HD 93206 A

    Science.gov (United States)

    Sanchez-Bermudez, J.; Alberdi, A.; Barbá, R.; Bestenlehner, J. M.; Cantalloube, F.; Brandner, W.; Henning, Th.; Hummel, C. A.; Maíz Apellániz, J.; Pott, J.-U.; Schödel, R.; van Boekel, R.

    2017-08-01

    Characterization of the dynamics of massive star systems and the astrophysical properties of the interacting components are a prerequisite for understanding their formation and evolution. Optical interferometry at milliarcsecond resolution is a key observing technique for resolving high-mass multiple compact systems. Here, we report on Very Large Telescope Interferometer/GRAVITY, Magellan/Folded-port InfraRed Echellette, and MPG2.2 m/FEROS observations of the late-O/early-B type system HD 93206 A, which is a member of the massive cluster Collinder 228 in the Carina nebula complex. With a total mass of about 90 {M}⊙ , it is one of the most compact massive quadruple systems known. In addition to measuring the separation and position angle of the outer binary Aa-Ac, we observe Brγ and He I variability in phase with the orbital motion of the two inner binaries. From the differential phase ({{{Δ }}}φ ) analysis, we conclude that the Brγ emission arises from the interaction regions within the components of the individual binaries, which is consistent with previous models for the X-ray emission of the system based on wind-wind interaction. With an average 3σ deviation of {{{Δ }}}φ ˜ 15^\\circ , we establish an upper limit of p ˜ 0.157 mas (0.35 au) for the size of the Brγ line-emitting region. Future interferometric observations with GRAVITY using the 8 m Unit Telescopes will allow us to constrain the line-emitting regions down to angular sizes of 20 μas (0.05 au at the distance of the Carina nebula).

  12. Integrated Analysis of Interferometric SAR, Satellite Altimetry and Hydraulic Modeling to Quantify Louisiana Wetland Dynamics

    Science.gov (United States)

    Lee, Hyongki; Kim, Jin-woo; Lu, Zhong; Jung, Hahn Chul; Shum, C. K.; Alsdorf, Doug

    2012-01-01

    Wetland loss in Louisiana has been accelerating due primarily to anthropogenic and nature processes, and is being advocated as a problem with national importance. Accurate measurement or modeling of wetland-wide water level changes, its varying extent, its storage and discharge changes resulting in part from sediment loads, erosion and subsidence are fundamental to assessment of hurricane-induced flood hazards and wetland ecology. Here, we use innovative method to integrate interferometric SAR (InSAR) and satellite radar altimetry for measuring absolute or geocentric water level changes and applied the methodology to remote areas of swamp forest in coastal Louisiana. Coherence analysis of InSAR pairs suggested that the HH polarization is preferred for this type of observation, and polarimetric analysis can help to identi:fy double-bonnce backscattering areas in the wetland. Envisat radar altimeter-measured 18- Hz (along-track sampling of 417 m) water level data processed with regional stackfile method have been used to provide vertical references for water bodies separated by levees. The high-resolution (approx.40 m) relative water changes measured from ALOS PALSAR L-band and Radarsat-l C-band InSAR are then integrated with Envisat radar altimetry to obtain absolute water level. The resulting water level time series were validated with in situ gauge observations within the swamp forest. Furthermore, we compare our water elevation changes with 2D flood modeling from LISFLOOD hydrodynamic model. Our study demonstrates that this new technique allows retrospective reconstruction and concurrent monitoring of water conditions and flow dynamics in wetlands, especially those lacking gauge networks.

  13. THE VLA NASCENT DISK AND MULTIPLICITY (VANDAM) SURVEY OF PERSEUS PROTOSTARS. RESOLVING THE SUB-ARCSECOND BINARY SYSTEM IN NGC 1333 IRAS2A

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, John J.; Looney, Leslie W. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Dunham, Michael M. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Li, Zhi-Yun [Department of Astronomy, University of Virginia, Charlottesville, VA 22903 (United States); Chandler, Claire J.; Perez, Laura M. [National Radio Astronomy Observatory, Socorro, NM 87801 (United States); Segura-Cox, Dominique; Harris, Robert J.; Hull, Charles L. H. [Department of Astronomy, University of Illinois, Urbana, IL 61801 (United States); Sadavoy, Sarah I. [Max-Planck-Institut für Astronomie, D-69117 Heidelberg (Germany); Melis, Carl [Center for Astrophysics and Space Sciences, University of California, San Diego, CA 92093 (United States); Kratter, Kaitlin [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Jørgensen, Jes K. [Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen Ø. (Denmark); Plunkett, Adele L., E-mail: jtobin@nrao.edu, E-mail: jeskj@nbi.dk [Department of Astronomy, Yale University, New Haven, CT 06520 (United States)

    2015-01-01

    We are conducting a Jansky Very Large Array (VLA) Ka-band (8 mm and 1 cm) and C-band (4 cm and 6.4 cm) survey of all known protostars in the Perseus Molecular Cloud, providing resolution down to ∼0.''06 and ∼0.''35 in the Ka band and C band, respectively. Here we present first results from this survey that enable us to examine the source NGC 1333 IRAS2A in unprecedented detail and resolve it into a protobinary system separated by 0.''621 ± 0.''006 (∼143 AU) at 8 mm, 1 cm, and 4 cm. These two sources (IRAS2A VLA1 and VLA2) are likely driving the two orthogonal outflows known to originate from IRAS2A. The brighter source IRAS2A VLA1 is extended perpendicular to its outflow in the VLA data, with a deconvolved size of 0.''055 (∼13 AU), possibly tracing a protostellar disk. The recently reported candidate companions (IRAS2A MM2 and MM3) are not detected in either our VLA data, Combined Array for Research in Millimeter-wave Astronomy (CARMA) 1.3 mm data, or Submillimeter Array (SMA) 850 μm data. SMA CO (J = 3 → 2), CARMA CO (J = 2 → 1), and lower-resolution CARMA CO (J = 1 → 0) observations are used to examine the outflow origins and the nature of the candidate companions to IRAS2A VLA1. The CO (J = 3 → 2) and (J = 2 → 1) data show that IRAS2A MM2 is coincident with a bright CO emission spot in the east-west outflow, and IRAS2A MM3 is within the north-south outflow. In contrast, IRAS2A VLA2 lies at the east-west outflow symmetry point. We propose that IRAS2A VLA2 is the driving source of the east-west outflow and a true companion to IRAS2A VLA1, whereas IRAS2A MM2 and MM3 may not be protostellar.

  14. The first interferometric detections of fast radio bursts

    Science.gov (United States)

    Caleb, M.; Flynn, C.; Bailes, M.; Barr, E. D.; Bateman, T.; Bhandari, S.; Campbell-Wilson, D.; Farah, W.; Green, A. J.; Hunstead, R. W.; Jameson, A.; Jankowski, F.; Keane, E. F.; Parthasarathy, A.; Ravi, V.; Rosado, P. A.; van Straten, W.; Venkatraman Krishnan, V.

    2017-07-01

    We present the first interferometric detections of fast radio bursts (FRBs), an enigmatic new class of astrophysical transient. In a 180-d survey of the Southern sky, we discovered three FRBs at 843 MHz with the UTMOST array, as a part of commissioning science during a major ongoing upgrade. The wide field of view of UTMOST (≈9 deg2) is well suited to FRB searches. The primary beam is covered by 352 partially overlapping fan-beams, each of which is searched for FRBs in real time with pulse widths in the range 0.655-42 ms, and dispersion measures ≤2000 pc cm-3. Detections of FRBs with the UTMOST array place a lower limit on their distances of ≈104 km (limit of the telescope near-field) supporting the case for an astronomical origin. Repeating FRBs at UTMOST or an FRB detected simultaneously with the Parkes radio telescope and UTMOST would allow a few arcsec localization, thereby providing an excellent means of identifying FRB host galaxies, if present. Up to 100 h of followup for each FRB has been carried out with the UTMOST, with no repeating bursts seen. From the detected position, we present 3σ error ellipses of 15 arcsec × 8.4° on the sky for the point of origin for the FRBs. We estimate an all-sky FRB rate at 843 MHz above a fluence F_lim of 11 Jy ms of ˜78 events sky-1 d-1 at the 95 per cent confidence level. The measured rate of FRBs at 843 MHz is two times higher than we had expected, scaling from the FRB rate at the Parkes radio telescope, assuming that FRBs have a flat spectral index and a uniform distribution in Euclidean space. We examine how this can be explained by FRBs having a steeper spectral index and/or a flatter logN-logF distribution than expected for a Euclidean Universe.

  15. Interferometric laser imaging for in-flight cloud droplet sizing

    Science.gov (United States)

    Dunker, Christina; Roloff, Christoph; Grassmann, Arne

    2016-12-01

    A non-intrusive particle sizing method with a high spatial distribution is used to estimate cloud droplet spectra during flight test campaigns. The interferometric laser imaging for droplet sizing (ILIDS) method derives particle diameters of transparent spheres by evaluating the out-of-focus image patterns. This sizing approach requires a polarized monochromatic light source, a camera including an objective lens with a slit aperture, a synchronization unit and a processing tool for data evaluation. These components are adapted to a flight test environment to enable the microphysical investigation of different cloud genera. The present work addresses the design and specifications of ILIDS system, flight test preparation and selected results obtained in the lower and middle troposphere. The research platform was a Dornier Do228-101 commuter aircraft at the DLR Flight Operation Center in Braunschweig. It was equipped with the required instrumentation including a high-energy laser as the light source. A comprehensive data set of around 71 800 ILIDS images was acquired over the course of five flights. The data evaluation of the characteristic ILIDS fringe patterns relies, among other things, on a relationship between the fringe spacing and the diameter of the particle. The simplest way to extract this information from a pattern is by fringe counting, which is not viable for such an extensive number of data. A brief contrasting comparison of evaluation methods based on frequency analysis by means of fast Fourier transform and on correlation methods such as minimum quadratic difference is used to encompass the limits and accuracy of the ILIDS method for such applications.

  16. On the COSMO-SkyMed Exploitation for Interferometric DEM Generation

    Science.gov (United States)

    Teresa, C. M.; Raffaele, N.; Oscar, N. D.; Fabio, B.

    2011-12-01

    DEM products for Earth observation space-borne applications are being to play a role of increasing importance due to the new generation of high resolution sensors (both optical and SAR). These new sensors demand elevation data for processing and, on the other hand, they provide new possibilities for DEM generation. Till now, for what concerns interferometric DEM, the Shuttle Radar Topography Mission (SRTM) has been the reference product for scientific applications all over the world. SRTM mission [1] had the challenging goal to meet the requirements for a homogeneous and reliable DEM fulfilling the DTED-2 specifications. However, new generation of high resolution sensors (including SAR) pose new requirements for elevation data in terms of vertical precision and spatial resolution. DEM are usually used as ancillary input in different processing steps as for instance geocoding and Differential SAR Interferometry. In this context, the recent SAR missions of DLR (TerraSAR-X and TanDEM-X) and ASI (COSMO-SkyMed) can play a promising role thanks to their high resolution both in space and time. In particular, the present work investigates the potentialities of the COSMO/SkyMed (CSK) constellation for ground elevation measurement with particular attention devoted to the impact of the improved spatial resolution wrt the previous SAR sensors. The recent scientific works, [2] and [3], have shown the advantages of using CSK in the monitoring of terrain deformations caused by landslides, earthquakes, etc. On the other hand, thanks to the high spatial resolution, CSK appears to be very promising in monitoring man-made structures, such as buildings, bridges, railways and highways, thus enabling new potential applications (urban applications, precise DEM, etc.). We present results obtained by processing both SPOTLIGHT and STRIPMAP acquisitions through standard SAR Interferometry as well as multi-pass interferometry [4] with the aim of measuring ground elevation. Acknowledgments

  17. Interferometric enhancement of x-ray reflectivity from unperturbed Langmuir monolayers of amphiphiles at the liquid-gas interface.

    Science.gov (United States)

    Krishnan, Venkata; Strzalka, Joseph; Liu, Jing; Liu, Chian; Kuzmenko, Ivan; Gog, Thomas; Blasie, J Kent

    2010-02-01

    Langmuir monolayers provide an important system for the investigation of the intramolecular structure and intermolecular ordering of organic and bio-organic macromolecular amphiphiles at an interface between polar and nonpolar media, e.g., the liquid-gas interface. Specular x-ray and neutron reflectivity have contributed substantially to these investigations. However, these reflectivity techniques are generally limited by the absence of crucial phase information, the relatively small contribution of the amphiphile to the scattering-length density contrast across the interface, and the relatively limited range of momentum transfer available perpendicular to the interface. Although several procedures have been developed to provide model-independent solutions to the phase problem, there remains a limited ability to distinguish features of slightly differing contrast (i.e., the "sensitivity") as well as their minimum allowable separation (i.e., the "spatial resolution") along the length of the scattering-length density profile derived from the reflectivity data via solution to the phase problem. Here, we demonstrate how the well-known interferometric approach can be extended to the structural investigation of otherwise unperturbed Langmuir monolayers of these amphiphiles to provide a direct solution to the phase problem and importantly, substantially enhance both the sensitivity and the spatial resolution in the derived profiles.

  18. San Francisco Bay Interferometric Side Scan Imagery: Area B

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — High resolution sonar data were collected over ultra-shallow areas of the San Francisco Bay estuary system. Bathymetric and acoustic backscatter data were collected...

  19. Advanced Interferometric Synthetic Aperture Imaging Radar (InSAR) for Dune Mapping

    Science.gov (United States)

    Havivi, Shiran; Amir, Doron; Schvartzman, Ilan; August, Yitzhak; Mamman, Shimrit; Rotman, Stanely R.; Blumberg, Dan G.

    2016-04-01

    Aeolian morphologies are formed in the presence of sufficient wind energy and available lose particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970s, remote sensing imagery, both optical and radar, have been used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two or more images. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR methods. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This work aims to demonstrate how interferometric decorrelation can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the coherence change detection method was used, in order to identify dune stability or instability and the dune activity level. The Nitzanim-Ashdod coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of

  20. A Concept of Dark Age Interferometric Array (DAIA)

    Science.gov (United States)

    Yan, Jingye

    After the epoch of recombination the Universe remained in neutral state until the large scale formation of galaxies released a sufficient number of ionizing photons to lightning the universe. In this period, the only emission is from the 21cm wavelength neutral hydrogen that may be observed today at 0.5-30MHz after the red shift. However, due to the ionosphere block and human/industrial RFI in this band, to observe the space from ground and also in the LOE is not possible. The concept of Dark Age Interferometric Array (DAIA) is aimed to place a linear array of nano-satellite with low noise receivers at the 10-1000m wavelength band in a lunar orbit. The distances between the nano-satellites are designed to form 1D uniformly distributed base lines in the uv-plane. A full coverage is then obtained after half rotation of the array in the orbit. The measurements are taken in the far side of the moon in order to have the lowest RFI from the earth. The thinned synthetic aperture linear array composed of ~15 elements (one small mother satellite and 14 nano daughter satellites) with the longest baseline over 100km. There are 3 dipoles antennas on each satellite in perpendicular to each other. Each of the antenna connected with a low-noise and periodically calibrated digital receiver. The received signals from each element are all sent to the mother satellite and processed onboard to generate the visibility functions for image processing. The mission composed of a mother satellite and 14 daughter satellites. The mass of the mother is ~110kg, and the mass of each daughter is <10kg. The complete set may be launched by CZ-2D carrier plus an upper stage or Vega. The mother satellite and 14 daughter satellites are bound onto a single structure during launch. When they arrive at the lunar orbit, the mother will release the daughters one by one according to the designs of the element spacing of the array with a controlled period of time. During the operation, daughters receive

  1. An overview of interferometric metrology and NDT techniques and applications for the aerospace industry

    Science.gov (United States)

    Georges, Marc P.; Thizy, Cédric; Languy, Fabian; Vandenrijt, Jean-François

    2016-08-01

    We review some full-field interferometric techniques which have been successfully applied in different applications related to the aerospace industry. The first part of the paper concerns the long-wave infrared (LWIR) digital holographic interferometry which allows the measurement large displacements that occur when space structures undergo large temperature excursions. A second part of the paper concerns different developments in interferometric nondestructive testing (NDT) techniques intended to improve their usability in aerospace industrial environments. Among others, we discuss LWIR speckle interferometry for simultaneous deformation and temperature variation measurements and new post-processing techniques applied to shearography for an easier detection of flaws in composite structures.

  2. Determination of the Size of Irregular Particles Using Interferometric Out-of-Focus Imaging

    Directory of Open Access Journals (Sweden)

    Marc Brunel

    2014-01-01

    Full Text Available We present a mathematical formalism to predict speckle-like interferometric out-of-focus patterns created by irregular scattering objects. We describe the objects by an ensemble of Dirac emitters. We show that it is not necessary to describe rigorously the scattering properties of an elliptical irregular object to predict some physical properties of the interferometric out-of-focus pattern. The fit of the central peak of the 2D autocorrelation of the pattern allows the prediction of the size of the scattering element. The method can be applied to particles in a size range from a tenth of micrometers to the millimeter.

  3. Unambiguous chirp characterization using modified-spectrum auto-interferometric correlation and pulse spectrum.

    Science.gov (United States)

    Yellampalle, B; Averitt, R D; Taylor, A J

    2006-09-18

    Modified-spectrum auto-interferometric correlation (MOSAIC), derived from a conventional second order interferometric autocorrelation trace, is a sensitive and visual chirp diagnostic method for ultrashort laser pulses. We construct several pairs of example pulse shapes that have nearly identical MOSAIC traces and demonstrate that chirp ambiguity can result when the field amplitude or spectrum are not known, thus making MOSAIC a qualitative tool for chirped pulses. However, when the pulse spectrum is known, a unique chirp reconstruction is possible. With the help of a new reconstruction technique, we experimentally demonstrate complete pulse characterization using MOSAIC envelopes and the pulse spectrum.

  4. Combining Single Dish and Interferometric data: a new tool in CASA

    Science.gov (United States)

    Teuben, Peter; Koda, Jin

    2018-01-01

    The basic mapping and deconvolution techniques used for (radio) interferometric data only works well for spatial scales that are sampled by the interferometer. Since interferometers cannot sample below a certain spacing, this implies spatial scales above a certain scale are not sampled. Our new tool converts the short spacings represented by a single dish map into a virtual radio interferometric dataset, and then performs a joint deconvolution of all spatial scales to recover a high fidelity image. Using recent ALMA data we will illustrate how this works.

  5. An analog modulation and demodulation method employing LVDT signal conditioner for fiber-optic interferometric sensors

    Science.gov (United States)

    Zhou, Kejiang; Rao, Qi; Zhang, Minjie; Hu, Keke; Ruan, Yefeng

    2017-09-01

    An analog method to modulate and demodulate fiber-optic interferometric sensors employing a linear variable differential transformer signal conditioner to generate sine modulation wave and demodulate phase-modulated signal from the photodetector’s output is presented in this letter. No external lock-in amplifiers or digital components are used in this design. All the necessary components for signal processing are integrated in a single analog electronic microchip AD698, which reduces the system’s complexity significantly. After implementation on an interferometric fiber-optic gyroscope as an example, this method demonstrates a bias stability of 0.063 deg h-1 (i.e. 0.220 µrad).

  6. EMISAR: C- and L-band polarimetric and interferometric SAR

    DEFF Research Database (Denmark)

    Christensen, Erik Lintz; Dall, Jørgen; Skou, Niels

    1996-01-01

    EMISAR is a C- and L-band fully polarimetric (i.e. 4 complex channel per frequency) synthetic aperture radar designed for remote sensing with high demands for resolution (2 m), polarization discrimination, and absolute radiometric and polarimetric calibration. The present installation has one 3-a...

  7. Segmentation of high-resolution InSar data of tropical forest using Fourier parameterised deformable models

    NARCIS (Netherlands)

    Varekamp, C.; Hoekman, D.H.

    2001-01-01

    Currently, tree maps are produced from field measurements that are time consuming and expensive. Application of existing techniques based on aerial photography is often hindered by cloud cover. This has initiated research into the segmentation of high resolution airborne interferometric Synthetic

  8. Optimization of GPS Interferometric Reflectometry for Remote Sensing

    Science.gov (United States)

    Chen, Qiang

    GPS Interferometric Reflectometry (GPS-IR), a passive microwave remote sensing technique utilizing GPS signal as a source of opportunity, characterizes the Earth's surface through a bistatic radar configuration. The key idea of GPS-IR is utilizing a ground-based antenna to coherently receive the direct, or line-of-sight (LOS), signal and the Earth's surface reflected signal simultaneously. The direct and reflected signals create an interference pattern of the Signal-to-Noise Ratio (SNR), which contains the information about the Earth's surface environment. GPS-IR has proven its utility in a variety of environmental remote sensing applications, including the measurements of near-surface soil moisture, coastal sea level, snow depth and snow water equivalent, and vegetation biophysical parameters. A major approach of the GPS-IR technique is using the SNR data provided by the global network of the geodetic GPS stations deployed for tectonic and surveying applications. The geodetic GPS networks provide wide spatial coverage and have no additional cost for this capability expansion. However, the geodetic GPS instruments have intrinsic limitations: the geodetic-quality GPS antennas are designed to suppress the reflected signals, which is counter to the requirement of GPS-IR. As a result, it is desirable to refine and optimize the instrument and realize the full potential of the GPS-IR technique. This dissertation first analyzes the signal characteristics of four available polarizations of the GPS signal, and then discusses how these characteristics are related to and can be used for remote sensing applications of GPS-IR. Two types of antennas, a half-wavelength dipole antenna and a patch antenna, are proposed and fabricated to utilize the desired polarizations. Four field experiments are conducted to assess the feasibility of the design criteria and the performance of the proposed antennas. Three experiments are focused on snow depth measurement. The Table Mountain

  9. Breast cancer detection using interferometric MUSIC: experimental and numerical assessment.

    Science.gov (United States)

    Ruvio, Giuseppe; Solimene, Raffaele; Cuccaro, Antonio; Gaetano, Domenico; Browne, Jacinta E; Ammann, Max J

    2014-10-01

    In microwave breast cancer detection, it is often beneficial to arrange sensors in close proximity to the breast. The resultant coupling generally changes the antenna response. As an a priori characterization of the radio frequency system becomes difficult, this can lead to severe degradation of the detection efficacy. The purpose of this paper is to demonstrate the advantages of adopting an interferometric multiple signal classification (I-MUSIC) approach due to its limited dependence from a priori information on the antenna. The performance of I-MUSIC detection was measured in terms of signal-to-clutter ratio (SCR), signal-to-mean ratio (SMR), and spatial displacement (SD) and compared to other common linear noncoherent imaging methods, such as migration and the standard wideband MUSIC (WB-MUSIC) which also works when the antenna is not accounted for. The data were acquired by scanning a synthetic oil-in-gelatin phantom that mimics the dielectric properties of breast tissues across the spectrum 1-3 GHz using a proprietary breast microwave multi-monostatic radar system. The phantom is a multilayer structure that includes skin, adipose, fibroconnective, fibroglandular, and tumor tissue with an adipose component accounting for 60% of the whole structure. The detected tumor has a diameter of 5 mm and is inserted inside a fibroglandular region with a permittivity contrast εr-tumor/εr-fibroglandular MUSIC method from antenna characterizations. The datasets were processed by using I-MUSIC, noncoherent migration, and wideband MUSIC under equivalent conditions (i.e., operative bandwidth, frequency samples, and scanning positions). SCR, SMR, and SD figures were measured from all reconstructed images. In order to benchmark experimental results, numerical simulations of equivalent scenarios were carried out by using CST Microwave Studio. The three numerical datasets were then processed following the same procedure that was designed for the experimental case. Detection

  10. Reduction of interferometric crosstalk induced penalty using a saturated semiconductor optical amplifier

    DEFF Research Database (Denmark)

    Liu, Fenghai; Zheng, Xueyan; Poulsen, Henrik Nørskov

    2000-01-01

    We successfully demonstrated that a simple saturated SOA could be used to reduce the impact from the interferometric crosstalk at 2.5 and 10 Gb/s. It is shown that 4 dB more crosstalk power can be tolerated at 1 dB penalty by using the SOA. This will greatly reduce the crosstalk requirement...

  11. Compensation of gain saturation in SOA-gates by interferometric Mach-Zehnder wavelength converters

    DEFF Research Database (Denmark)

    Danielsen, Søren Lykke; Jørgensen, Carsten; Hansen, Peter Bukhave

    1996-01-01

    Compensation of signal degradation in semiconductor optical amplifier (SOA) gates for optical switch nodes using all-active integrated Mach-Zehnder interferometric wavelength converters is experimentally demonstrated at 2.5 and 10 Gb/s. More than 10 dB improvement of the dynamic range is obtained...

  12. Cascadability of broadcast and select switch blocks with interferometric wavelength converters at 10 Gbit/s

    DEFF Research Database (Denmark)

    Hansen, Peter Bukhave; Jørgensen, Carsten; Danielsen, Søren Lykke

    1997-01-01

    In conclusion, it is demonstrated that the use of interferometric wavelength convertors (IWCs) in the broadcast and select packet switch block results in an improved cascadability. Furthermore, it is predicted that successful concatenation of eight 8 x 8 and four 16 X 16 switch blocks is possible...

  13. Interferometric SAR Coherence Models for Characterization of Hemiboreal Forests Using TanDEM-X Data

    Directory of Open Access Journals (Sweden)

    Aire Olesk

    2016-08-01

    Full Text Available In this study, four models describing the interferometric coherence of the forest vegetation layer are proposed and compared with the TanDEM-X data. Our focus is on developing tools for hemiboreal forest height estimation from single-pol interferometric SAR measurements, suitable for wide area forest mapping with limited a priori information. The multi-temporal set of 19 TanDEM-X interferometric pairs and the 90th percentile forest height maps are derived from Airborne LiDAR Scanning (ALS, covering an area of 2211 ha of forests over Estonia. Three semi-empirical models along with the Random Volume over Ground (RVoG model are examined for applicable parameter ranges and model performance under various conditions for over 3000 forest stands. This study shows that all four models performed well in describing the relationship between forest height and interferometric coherence. Use of an advanced model with multiple parameters is not always justified when modeling the volume decorrelation in the boreal and hemiboreal forests. The proposed set of semi-empirical models, show higher robustness compared to a more advanced RVoG model under a range of seasonal and environmental conditions during data acquisition. We also examine the dynamic range of parameters that different models can take and propose optimal conditions for forest stand height inversion for operationally-feasible scenarios.

  14. Integrating interferometric SAR data with levelling measurements of land subsidence using geostatistics

    NARCIS (Netherlands)

    Zhou, Y.; Stein, A.; Molenaar, M.

    2003-01-01

    Differential Synthetic Aperture Radar (SAR) interferometric (D-InSAR) data of ground surface deformation are affected by several error sources associated with image acquisitions and data processing. In this paper, we study the use of D-InSAR for quantifying land subsidence due to groundwater

  15. Interferometric signals analysis based on the extended Kalman filter tuned by machine learning technique

    Science.gov (United States)

    Ermolaev, Petr A.; Volynsky, Maxim A.

    2017-06-01

    The paper deals with the machine learning approach to automatic tuning of extended Kalman filter in application to interferometric signals processing. The representation of interferometric signals as output of dynamic systems with varying state vector is presented. It is shown that the challenge of the extended Kalman filter application to interferometric data processing is selection of initial parameters for the filter. The complex tuning problem is described in a formal form. The machine learning approach to the automatic filter tuning is proposed. The combination of Monte Carlo optimization and the gradient descent are implemented for initial filter parameters selection. The optimization criterion in the form of sum differences between measured and estimated signal value is presented and discussed. The results of simulated and experimental interferometric signals processing are presented and analyzed. The quality of amplitude and phase estimation by the automatically tuned filter is at the same level as hand tuned filter. It is shown, that proposed approach allows to obtain robust results of experimental data processing.

  16. Determining Snow Depth Using Airborne Multi-Pass Interferometric Synthetic Aperture Radar

    Science.gov (United States)

    2013-09-01

    The high albedo of snow greatly impacts the local and global scale radiational balance. The snow decreases the absorption of solar energy...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA DISSERTATION Approved for public release: distribution is unlimited DETERMINING SNOW ...DATES COVERED Dissertation 4. TITLE AND SUBTITLE DETERMINING SNOW DEPTH USING AIRBORNE MULTI-PASS INTERFEROMETRIC SYNTHETIC APERTURE RADAR 5

  17. A new method for bidimensional analysis of interferometric patterns of liquid films.

    Science.gov (United States)

    Nogueira, Rui; Vazquez, Rosa; Mata, José Luís; Saramago, Benilde

    2005-06-01

    A new method for bidimensional analysis of interferometric patterns of wetting liquid films obtained with the captive bubble technique is described. This method replaces one-dimensional analysis along various intensity profiles with analysis of one average intensity profile. The advantage is to concentrate the surface characteristics of the whole film image into a single intensity profile.

  18. The flight test of Pi-SAR(L) for the repeat-pass interferometric SAR

    Science.gov (United States)

    Nohmi, Hitoshi; Shimada, Masanobu; Miyawaki, Masanori

    2006-09-01

    This paper describes the experiment of the repeat pass interferometric SAR using Pi-SAR(L). The air-borne repeat-pass interferometric SAR is expected as an effective method to detect landslide or predict a volcano eruption. To obtain a high-quality interferometric image, it is necessary to make two flights on the same flight pass. In addition, since the antenna of the Pi-SAR(L) is secured to the aircraft, it is necessary to fly at the same drift angle to keep the observation direction same. We built a flight control system using an auto pilot which has been installed in the airplane. This navigation system measures position and altitude precisely with using a differential GPS, and the PC Navigator outputs a difference from the desired course to the auto pilot. Since the air density is thinner and the speed is higher than the landing situation, the gain of the control system is required to be adjusted during the repeat pass flight. The observation direction could be controlled to some extent by adjusting a drift angle with using a flight speed control. The repeat-pass flight was conducted in Japan for three days in late November. The flight was stable and the deviation was within a few meters for both horizontal and vertical direction even in the gusty condition. The SAR data were processed in time domain based on range Doppler algorism to make the complete motion compensation. Thus, the interferometric image processed after precise phase compensation is shown.

  19. Coastal sea level from inland CryoSat-2 interferometric SAR altimetry

    DEFF Research Database (Denmark)

    Abulaitijiang, Adili; Andersen, Ole Baltazar; Stenseng, Lars

    2015-01-01

    The European Space Agency's CryoSat-2 satellite can operate in a novel synthetic aperture radar interferometric (SARIn) mode where its nominal footprint (swath) is observed by two antennas and the phase difference between the signals is used to determination the exact location of the scatterer...

  20. Interferometric methods for mapping static electric and magnetic fields

    DEFF Research Database (Denmark)

    Pozzi, Giulio; Beleggia, Marco; Kasama, Takeshi

    2014-01-01

    The mapping of static electric and magnetic fields using electron probes with a resolution and sensitivity that are sufficient to reveal nanoscale features in materials requires the use of phase-sensitive methods such as the shadow technique, coherent Foucault imaging and the Transport of Intensity......) the model-independent determination of the locations and magnitudes of field sources (electric charges and magnetic dipoles) directly from electron holographic data....

  1. White-light spectral interferometric techniques used to measure the group dispersion of isotropic and anisotropic optical elements

    Science.gov (United States)

    Hlubina, P.; Ciprian, D.; Chlebus, R.

    2007-06-01

    We present two di.erent white-light spectral interferometric techniques employing a low-resolution spectrometer for a direct measurement of the group dispersion of isotropic and anisotropic optical elements. First, the dispersion of the group refractive index for glass plate is measured in a Michelson interferometer with the plate of known thickness inserted in one of the interferometer arms. The technique utilizes the spectrometer to record a series of spectral interferograms for measuring the equalization wavelength as a function of the displacement of the interferometer mirror from the reference position, which corresponds to a balanced Michelson interferometer. The use of the technique is extended for measuring the dispersion of the group refractive indices for the ordinary and extraordinary polarizations in a quartz crystal. We con.rm that the measured group dispersions agree well with those resulting from the semiempirical dispersion equations. We also show that the measured mirror displacement depends, in accordance with the theory, linearly on the theoretical group refractive index and that the slope of the corresponding straight line gives precisely the thickness of the quartz crystal. Second, the group dispersion of the quartz crystal is measured in an unbalanced Mach-Zehnder interferometer with the adjustable path length when the crystal is inserted in the test arm. The use of the second technique is extended for measuring the di.erential group dispersion of a glass of a holey optical fiber.

  2. Using temporarily coherent point interferometric synthetic aperture radar for land subsidence monitoring in a mining region of western China

    Science.gov (United States)

    Fan, Hongdong; Xu, Qiang; Hu, Zhongbo; Du, Sen

    2017-04-01

    Yuyang mine is located in the semiarid western region of China where, due to serious land subsidence caused by underground coal exploitation, the local ecological environment has become more fragile. An advanced interferometric synthetic aperture radar (InSAR) technique, temporarily coherent point InSAR, is applied to measure surface movements caused by different mining conditions. Fifteen high-resolution TerraSAR-X images acquired between October 2, 2012, and March 27, 2013, were processed to generate time-series data for ground deformation. The results show that the maximum accumulated values of subsidence and velocity were 86 mm and 162 mm/year, respectively; these measurements were taken above the fully mechanized longwall caving faces. Based on the dynamic land subsidence caused by the exploitation of one working face, the land subsidence range was deduced to have increased 38 m in the mining direction with 11 days' coal extraction. Although some mining faces were ceased in 2009, they could also have contributed to a small residual deformation of overlying strata. Surface subsidence of the backfill mining region was quite small, the maximum only 21 mm, so backfill exploitation is an effective method for reducing the land subsidence while coal is mined.

  3. Distinguishing between ultrafast optical harmonic generation and multi-photon-induced luminescence from ZnO thin films by frequency-resolved interferometric autocorrelation microscopy.

    Science.gov (United States)

    Schmidt, S; Mascheck, M; Silies, M; Yatsui, T; Kitamura, K; Ohtsu, M; Lienau, C

    2010-11-22

    The nonlinear optical properties of thin ZnO film are studied using interferometric autocorrelation (IFRAC) microscopy. Ultrafast, below-bandgap excitation with 6-fs laser pulses at 800 nm focused to a spot size of 1 µm results in two emission bands in the blue and blue-green spectral region with distinctly different coherence properties. We show that an analysis of the wavelength-dependence of the interference fringes in the IFRAC signal allows for an unambiguous assignment of these bands as coherent second harmonic emission and incoherent, multiphoton-induced photoluminescence, respectively. More generally our analysis shows that IFRAC allows for a complete characterization of the coherence properties of the nonlinear optical emission from nanostructures in a single-beam experiment. Since this technique combines a very high temporal and spatial resolution we anticipate broad applications in nonlinear nano-optics.

  4. Distinguishing between ultrafast optical harmonic generation and multi-photon-induced luminescence from ZnO thin films by interferometric frequency-resolved autocorrelation microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Slawa; Mascheck, Manfred; Silies, Martin [Carl-von-Ossietzky-Universitaet, Oldenburg (Germany); Yatsui, Takashi; Kitamura, Kokoro; Ohtsu, Motoichi; Lienau, Christoph [University of Tokyo (Japan)

    2011-07-01

    The nonlinear optical properties of a thin ZnO film are studied using interferometric frequency-resolved autocorrelation (IFRAC) microscopy. By exciting the film with 6-fs, below-bandgap laser pulses at 800nm focused to a spot size of 1 {mu}m two emission bands in the blue and bluegreen spectral region with distinctly different coherence properties can be detected. We show that an analysis of the wavelength-dependence of the interference fringes in the IFRAC signal allows for an unambiguous assignment of these bands as coherent second harmonic emission and incoherent, multiphoton-induced photoluminescence, respectively. More generally our analysis shows that IFRAC allows for a complete characterization of the coherence properties of the nonlinear optical emission from nanostructures in a single-beam experiment. Since this technique combines a very high temporal and spatial resolution we anticipate broad applications in nonlinear nano-optics.

  5. Resolution and super-resolution.

    Science.gov (United States)

    Sheppard, Colin J R

    2017-06-01

    Many papers have claimed the attainment of super-resolution, i.e. resolution beyond that achieved classically, by measurement of the profile of a feature in the image. We argue that measurement of the contrast of the image of a dark bar on a bright background does not give a measure of resolution, but of detection sensitivity. The width of a bar that gives an intensity at the center of the bar of 0.735 that in the bright region (the same ratio as in the Rayleigh resolution criterion) is λ/(13.9×numerical aperture) for the coherent case with central illumination. This figure, which compares with λ/(numerical aperture) for the Abbe resolution limit with central illumination, holds for the classical case, and so is no indication of super-resolution. Theoretical images for two points, two lines, arrays of lines, arrays of bars, and grating objects are compared. These results can be used a reference for experimental results, to determine if super-resolution has indeed been attained. The history of the development of the theory of microscope resolution is outlined. © 2017 Wiley Periodicals, Inc.

  6. Resolution and Functionality Enhancements in Optical Metrology

    Science.gov (United States)

    Gillmer, Steven R.

    The effective implementation of optical metrology and its associated instrumentation involves a multi-disciplinary approach. This dissertation will draw from mechanical, electrical, and optical engineering subject areas in order to implement the proposed resolution and functionality enhancements. The discussion will focus on three forms of optical metrology: optical displacement sensing, scatterometry, and interferometric weak measurements. A variety of novel concepts and experiments will be presented within these fields of research. First, in optical displacement sensing, increased degree-of-freedom measurements will be explored. The development of a three degree-of-freedom displacement measuring interferometer will serve as the foundation for a six degree-of-freedom optical measurement system. In the pursuit of simultaneous six axis measurement, novel straightness and roll angle sensors will develop. Second, a novel form of scatterometry that uses a spatially varying polarization applied to a focused beam will be presented. The principles of precision control and optical holography are necessary in the system development of the instrument. It will be shown that lateral scanning applied to the inspected sample greatly enhances sensitivity to changes in process parameters. Finally, optical displacement sensing and scatterometry will find parallels through weak measurements. Both application areas have potential for vast performance improvements via the measurement of a weak value. The feasibility of weak value amplification will be investigated for optical roll sensing and the novel scatterometry approach using an interferometric analogy.

  7. Exploitation of a large COSMO-SkyMed interferometric dataset

    Science.gov (United States)

    Nutricato, Raffaele; Nitti, Davide O.; Bovenga, Fabio; Refice, Alberto; Chiaradia, Maria T.

    2014-10-01

    In this work we explored a dataset made by more than 100 images acquired by COSMO-SkyMed (CSK) constellation over the Port-au-Prince (Haiti) metropolitan and surrounding areas that were severely hit by the January 12th, 2010 earthquake. The images were acquired along ascending pass by all the four sensors of the constellation with a mean rate of 1 acquisition/week. This consistent CSK dataset was fully exploited by using the Persistent Scatterer Interferometry algorithm SPINUA with the aim of: i) providing a displacement map of the area; ii) assessing the use of CSK and PSI for ground elevation measurements; iii) exploring the CSK satellite orbital tube in terms of both precision and size. In particular, significant subsidence phenomena were detected affecting river deltas and coastal areas of the Port-au-Prince and Carrefour region, as well as very slow slope movements and local ground instabilities. Ground elevation was also measured on PS targets with resolution of 3m. The density of these measurable targets depends on the ground coverage, and reaches values higher than 4000 PS/km2 over urban areas, while it drops over vegetated areas or along slopes affected by layover and shadow. Heights values were compared with LIDAR data at 1m of resolution collected soon after the 2010 earthquake. Furthermore, by using geocoding procedures and the precise LIDAR data as reference, the orbital errors affecting CSK records were investigated. The results are in line with other recent studies.

  8. Interferometric Characterization of the Earth's Atmosphere from Lagrange Point 2

    Science.gov (United States)

    Herman, Jay R.; Komar, George (Technical Monitor)

    2001-01-01

    Part of the NASA plans for future Earth Science missions calls for observations using novel vantage points that can produce science products otherwise unobtainable. Observations of the Earth from the Lagrange-2 point, L-2, (1.5 million km behind the Earth on the Earth-Sun line) affords a unique vantage point for atmospheric science. Spectral observation of the Earth's atmosphere using solar occultation techniques in the near infrared (1 to 4 microns) provides one of the most accurate methods of passively sensing attitude profiles of the major species (CO2, O3, O2, CH4, H2O N2O). While traditional polar orbiting occultation measurements can obtain about 14 measurements per day (2 per orbit), solar occultation observations from the Lagrange-2 point will yield hourly profile measurements at all latitudes. The expected spatial resolution is 2 km in altitude, 0.5 degrees in latitude, and 2 degrees in longitude. The result from 24 hours of observations will be a three-dimensional map of atmospheric composition. To accomplish this task from L-2 requires the development of a large moderate spectral resolution instrument whose entrance aperture is about 10 meters. Use of a standard telescope design with a 10-meter circular mirror or a 10-meter strip mirror would be prohibitively expensive and excessively massive. Instead, we are proposing the development of a 10-meter linear interferometer coupled to a Fourier transform imaging spectrometer. The result will be a highly efficient design with sufficient sensitivity, while having both spatial and spectral resolution to produce the desired results. Preliminary calculations show that seven species (CO2, O3, O2, CH4, H2O N2O) have clearly separated spectral features in the I to 4 microns range with sufficient absorption to produce profile information from near the Earth's surface to the middle stratosphere. For CO2 the estimated sensitivity to change is 0.33% or 1 part in 330. This should be sufficient to detect changes that are

  9. Measurement uncertainty budget of an interferometric flow velocity sensor

    Science.gov (United States)

    Bermuske, Mike; Büttner, Lars; Czarske, Jürgen

    2017-06-01

    Flow rate measurements are a common topic for process monitoring in chemical engineering and food industry. To achieve the requested low uncertainties of 0:1% for flow rate measurements, a precise measurement of the shear layers of such flows is necessary. The Laser Doppler Velocimeter (LDV) is an established method for measuring local flow velocities. For exact estimation of the flow rate, the flow profile in the shear layer is of importance. For standard LDV the axial resolution and therefore the number of measurement points in the shear layer is defined by the length of the measurement volume. A decrease of this length is accompanied by a larger fringe distance variation along the measurement axis which results in a rise of the measurement uncertainty for the flow velocity (uncertainty relation between spatial resolution and velocity uncertainty). As a unique advantage, the laser Doppler profile sensor (LDV-PS) overcomes this problem by using two fan-like fringe systems to obtain the position of the measured particles along the measurement axis and therefore achieve a high spatial resolution while it still offers a low velocity uncertainty. With this technique, the flow rate can be estimated with one order of magnitude lower uncertainty, down to 0:05% statistical uncertainty.1 And flow profiles especially in film flows can be measured more accurately. The problem for this technique is, in contrast to laboratory setups where the system is quite stable, that for industrial applications the sensor needs a reliable and robust traceability to the SI units, meter and second. Small deviations in the calibration can, because of the highly position depending calibration function, cause large systematic errors in the measurement result. Therefore, a simple, stable and accurate tool is needed, that can easily be used in industrial surroundings to check or recalibrate the sensor. In this work, different calibration methods are presented and their influences to the

  10. Nano-Hertz Gravitational Waves Searches with Interferometric Pulsar Timing Experiments

    CERN Document Server

    Tinto, Massimo

    2011-01-01

    We estimate the sensitivity to nano-Hertz gravitational waves of pulsar timing experiments in which two highly-stable millisecond pulsars are tracked simultaneously with two neighboring radio telescopes that are referenced to the same time-keeping subsystem (i.e. "the clock"). By taking the difference of the two time-of-arrival residual data streams we can exactly cancel the clock noise in the combined data set, thereby enhancing the sensitivity to gravitational waves. We estimate that, in the band ($10^{-9} - 10^{-8}$) Hz, this "interferometric" pulsar timing technique can potentially improve the sensitivity to gravitational radiation by almost two orders of magnitude over that of single-telescopes. Interferometric pulsar timing experiments could be performed with neighboring pairs of antennas of the forthcoming large arraying projects.

  11. Interferometric microstructured polymer optical fiber ultrasound sensor for optoacoustic endoscopic imaging in biomedical applications

    DEFF Research Database (Denmark)

    Gallego, Daniel; Sáez-Rodríguez, David; Webb, David

    2014-01-01

    We report a characterization of the acoustic sensitivity of microstructured polymer optical fiber interferometric sensors at ultrasonic frequencies from 100kHz to 10MHz. The use of wide-band ultrasonic fiber optic sensors in biomedical ultrasonic and optoacoustic applications is an open alternative...... to conventional piezoelectric transducers. These kind of sensors, made of biocompatible polymers, are good candidates for the sensing element in an optoacoustic endoscope because of its high sensitivity, its shape and its non-brittle and non-electric nature. The acoustic sensitivity of the intrinsic fiber optic...... interferometric sensors depends strongly of the material which is composed of. In this work we compare experimentally the intrinsic ultrasonic sensitivities of a PMMA mPOF with other three optical fibers: a singlemode silica optical fiber, a single-mode polymer optical fiber and a multimode graded...

  12. Measurement of the defect size by shearography or other interferometric techniques

    Science.gov (United States)

    Michel, Fabrice; Renotte, Yvon L.; Habraken, Serge

    2012-03-01

    Shearography is an interferometric technique suitable for detecting defects because they yield singular fringes and high phase values in wrapped and unwrapped phasemaps, respectively. We propose a methodology that leads to the defect size from unwrapped phasemap by extracting the size of the high phase values area. The area size is evaluated, thanks to a wavelet transform algorithm that enables the location of its borders. The performances of the methodology and of the algorithm have been tested by applying them on a defect where the size is known. An error less than 1.5% root mean square was reached. Our approach is independent of the shearing amount and of the phase profile, and it can be extended for other interferometric techniques.

  13. Interferometric measurement of displacements and displacement velocities for nondestructive quality control

    Science.gov (United States)

    Shpeĭzman, V. V.; Peschanskaya, N. N.

    2007-07-01

    It is shown that the interferometric measurement of small displacements and small-displacement velocities can be used to determine internal stresses or the stresses induced by an applied load in solids and to control structural changes in them. The interferometric method based on the measurement of the reaction of a solid to a small perturbation in its state of stress is applied to determine stresses from the deviation of the reaction to perturbations from that in the standard stress-free case. For structural control, this method is employed to study the specific features of the characteristics of microplastic deformation that appear after material treatment or operation and manifest themselves in the temperature and force dependences of the rate of a small inelastic strain.

  14. Investigations into the Uncertainties of Interferometric Measurements of Linear and Circular Vibrations

    Directory of Open Access Journals (Sweden)

    Hans-Jürgen von Martens

    1997-01-01

    Full Text Available A uniform description is given of a method of measurement using a Michelson interferometer for measuring the linear motion quantities acceleration, velocity and displacement, and a diffraction grating interferometer for measuring the circular motion quantities angular acceleration, angular velocity and rotation angle. The paper focusses on an analysis of the dynamic behaviour of an interferometric measurement system based on the counting technique with regard to the measurement errors due to deterministic and stochastic disturbing quantities. The error analysis and description presented are aimed at giving some rules, mathematical expressions and graphical presentations that have proved to be helpful in recognizing the errors in interferometric measurements of motion quantities, optimizing the measurement conditions (e.g., filter settings, obtaining corrections and estimating the uncertainty of measurement.

  15. Instrumentation for ice crystal characterization in laboratory using interferometric out-of-focus imaging

    Science.gov (United States)

    Brunel, M.; Demange, G.; Fromager, M.; Talbi, M.; Zapolsky, H.; Patte, R.; Aït Ameur, K.; Jacquot-Kielar, J.; Coetmellec, S.; Gréhan, G.; Quevreux, B.

    2017-08-01

    Airborne characterization of ice crystals has important applications. The extreme difficulty of realizing in situ tests requires the development of a complete instrumentation in the laboratory. Such an installation should enable design, development, test, and calibration of instruments in conditions as close as possible to real ones. We present a set of numerical and experimental tools that have been developed to realize ice crystal sensors based on interferometric particle imaging. The set of tools covers the development of complementary simulators for crystal growth and interferometric particle imaging predictions, experimental generation of "programmable" ice crystals, and instrumentation of a freezing column where different techniques as in-focus imaging, out-of-focus imaging, and digital in-line holography can be combined simultaneously for test and calibration.

  16. JouFLU: upgrades to the fiber linked unit for optical recombination (FLUOR) interferometric beam combiner.

    Science.gov (United States)

    Scott, N. J.; Lhomé, E.; ten Brummelaar, T. A.; Coudé du Foresto, V.; Millan-Gabet, R.; Sturmann, J.; Sturmann, L.

    2014-07-01

    The Fiber Linked Unit for Optical Recombination (FLUOR) is a precision interferometric beam combiner operating at the CHARA Array on Mt. Wilson, CA. It has recently been upgraded as part of a mission known as "Jouvence of FLUOR" or JouFLU. As part of this program JouFLU has new mechanic stages and optical payloads, new alignment systems, and new command/control software. Furthermore, new capabilities have been implemented such as a Fourier Transform Spectrograph (FTS) mode and spectral dispersion mode. These upgrades provide new capabilities to JouFLU as well as improving statistical precision and increasing observing efficiency. With these new systems, measurements of interferometric visibility to the level of 0.1% precision are expected on targets as faint as 6th magnitude in the K band. Here we detail the upgrades of JouFLU and report on its current status.

  17. Interferometric microstructured polymer optical fiber ultrasound sensor for optoacoustic endoscopic imaging in biomedical applications

    Science.gov (United States)

    Gallego, Daniel; Sáez-Rodríguez, David; Webb, David; Bang, Ole; Lamela, Horacio

    2014-05-01

    We report a characterization of the acoustic sensitivity of microstructured polymer optical fiber interferometric sensors at ultrasonic frequencies from 100kHz to 10MHz. The use of wide-band ultrasonic fiber optic sensors in biomedical ultrasonic and optoacoustic applications is an open alternative to conventional piezoelectric transducers. These kind of sensors, made of biocompatible polymers, are good candidates for the sensing element in an optoacoustic endoscope because of its high sensitivity, its shape and its non-brittle and non-electric nature. The acoustic sensitivity of the intrinsic fiber optic interferometric sensors depends strongly of the material which is composed of. In this work we compare experimentally the intrinsic ultrasonic sensitivities of a PMMA mPOF with other three optical fibers: a singlemode silica optical fiber, a single-mode polymer optical fiber and a multimode graded-index perfluorinated polymer optical fiber.

  18. Tuning fork enhanced interferometric photoacoustic spectroscopy: a new method for trace gas analysis

    Science.gov (United States)

    Köhring, M.; Pohlkötter, A.; Willer, U.; Angelmahr, M.; Schade, W.

    2011-01-01

    A photoacoustic trace gas sensor based on an optical read-out method of a quartz tuning fork is shown. Instead of conventional piezoelectric signal read-out, as applied in well-known quartz-enhanced photoacoustic spectroscopy (QEPAS), an interferometric read-out method for measurement of the tuning fork's oscillation is presented. To demonstrate the potential of the optical read-out of tuning forks in photoacoustics, a comparison between the performances of a sensor with interferometric read-out and conventional QEPAS with piezoelectric read-out is reported. The two sensors show similar characteristics. The detection limit (L) for the optical read-out is determined to be L opt=(2598±84) ppm (1 σ) compared to L elec=(2579±78) ppm (1 σ) for piezoelectric read-out. In both cases the detection limit is defined by the thermal noise of the tuning fork.

  19. Transmission enhancement by deployment of interferometric wavelength converters within all-optical cross connects

    DEFF Research Database (Denmark)

    Poulsen, Henrik Nørskov; Mikkelsen, Benny; Stubkjær, Kristian

    1997-01-01

    Wavelength-division multiplexing (WDM) networks are expected to utilize all-optical cross connects (OXCN) for signal routing. Because a signal path is likely to contain a number of OXCNs, their cascadability is essential. Furthermore, because wavelength converters in the OXCNs improve traffic per...... performance and ease network management, their cascadability, in particular, is important. Using interferometric wavelength converters (IWCs) we have previously demonstrated experimentally a cascade of 10 converters at 10 Gbit/s with...

  20. Orthogonal ribbons for suspending test masses in interferometric gravitational wave detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.H. [School of Physics, University of Western Australia, Crawley 6009, WA (Australia)]. E-mail: bhl@physics.uwa.edu.au; Ju, L. [School of Physics, University of Western Australia, Crawley 6009, WA (Australia); Blair, D.G. [School of Physics, University of Western Australia, Crawley 6009, WA (Australia)

    2005-05-23

    We show that a simple modification of proposed ribbon suspensions for laser interferometric gravitational wave detectors can substantially reduce the amplitude of violin modes at the expense of a small deterioration of suspension thermal noise. Using low loss fused silica, large amplitude peaks which cause dynamic range problems can be reduced by 21 dB. The total number of horizontal longitudinal direction violin modes below 5 kHz is reduced to less than half that expected with conventional ribbon suspensions.

  1. Infrared Interferometric Gravity Darkening Observations of Vega with CHARA/FLUOR

    Science.gov (United States)

    Aufdenberg, J.; Mérand, A.; Coudé du Foresto, V.; Absil, O.; di Folco, E.; Kervella, P.; Ridgway, S.; Berger, D.; ten Brummelaar, T.; McAlister, H.; Sturmann, J.; Turner, N.

    We have obtained high-precision measurements of Vega at projected baselines between 103 m and 273 m with the CHARA Array using the (FLUOR) beam combiner in the K' band. A strongly gravity-darkened model atmosphere is in general agreement with both our interferometric data and archival spectrophotometry. This model indicates that Vega is rotating at 91%ofitsangular break-uprateandthatthepole-to-equator effectivetemperaturedifference is 2250 K.

  2. Spectral phase retrieval from interferometric autocorrelation by a combination of graduated optimization and genetic algorithms.

    Science.gov (United States)

    Yang, Wenlong; Springer, Matthew; Strohaber, James; Kolomenski, Alexandre; Schuessler, Hans; Kattawar, George; Sokolov, Alexei

    2010-07-05

    We describe a method for retrieving spectral phase information from second harmonic interferometric autocorrelation measurements supplemented by the use of the observed spectral intensity. By applying a combination of graduated optimization and genetic algorithms, accurate phase retrieval of laser pulses as short as a few optical cycles was obtained from the measured autocorrelation and spectral intensity. The effectiveness of the combined algorithms is demonstrated on a set of significantly different femtosecond pulse shapes.

  3. Interferometric characterization of ultrashort deep ultraviolet pulses using a multiphoton ionization mass spectrometer.

    Science.gov (United States)

    Zaitsu, Shin-ichi; Miyoshi, Yuki; Kira, Fumiaki; Yamaguchi, Satoshi; Uchimura, Tomohiro; Imasaka, Tatoro

    2007-06-15

    The temporal characterization of a femtosecond laser pulse in the deep ultraviolet region using an interferometric autocorrelation scheme is demonstrated. Two-photon ionization of a molecule in a time-of-flight mass spectrometer was used as a nonlinear detector to obtain an autocorrelation trace. This setup proved useful in not only providing a temporal characterization of a pulse but also investigating the ultrafast dynamics of photochemical processes.

  4. Laser-diode interferometric heterodyne vibrometer: application to linear motor control.

    Science.gov (United States)

    Chebbour, A; Gharbi, T; Tribillon, G

    2001-11-01

    We describe an interferometric heterodyne vibrometer that uses a laser diode with a triangular modulation frequency. This optical sensor is used to probe a vibrating polished surface. As an illustration of the sensor performance, the control of nonuniform velocity of a linear motor is achieved. The technique can be used over a large bandwidth between a few hertz and several tens of kilohertz. Generalization of the technique to the sensing of frequency vibrations is also demonstrated theoretically.

  5. Seismic time-lapse imaging using Interferometric least-squares migration

    KAUST Repository

    Sinha, Mrinal

    2016-09-06

    One of the problems with 4D surveys is that the environmental conditions change over time so that the experiment is insufficiently repeatable. To mitigate this problem, we propose the use of interferometric least-squares migration (ILSM) to estimate the migration image for the baseline and monitor surveys. Here, a known reflector is used as the reference reflector for ILSM. Results with synthetic and field data show that ILSM can eliminate artifacts caused by non-repeatability in time-lapse surveys.

  6. Dynamic measurements of flowing cells labeled by gold nanoparticles using full-field photothermal interferometric imaging

    Science.gov (United States)

    Turko, Nir A.; Roitshtain, Darina; Blum, Omry; Kemper, Björn; Shaked, Natan T.

    2017-06-01

    We present highly dynamic photothermal interferometric phase microscopy for quantitative, selective contrast imaging of live cells during flow. Gold nanoparticles can be biofunctionalized to bind to specific cells, and stimulated for local temperature increase due to plasmon resonance, causing a rapid change of the optical phase. These phase changes can be recorded by interferometric phase microscopy and analyzed to form an image of the binding sites of the nanoparticles in the cells, gaining molecular specificity. Since the nanoparticle excitation frequency might overlap with the sample dynamics frequencies, photothermal phase imaging was performed on stationary or slowly dynamic samples. Furthermore, the computational analysis of the photothermal signals is time consuming. This makes photothermal imaging unsuitable for applications requiring dynamic imaging or real-time analysis, such as analyzing and sorting cells during fast flow. To overcome these drawbacks, we utilized an external interferometric module and developed new algorithms, based on discrete Fourier transform variants, enabling fast analysis of photothermal signals in highly dynamic live cells. Due to the self-interference module, the cells are imaged with and without excitation in video-rate, effectively increasing signal-to-noise ratio. Our approach holds potential for using photothermal cell imaging and depletion in flow cytometry.

  7. Wide-field interferometric phase microscopy with molecular specificity using plasmonic nanoparticles.

    Science.gov (United States)

    Turko, Nir A; Peled, Anna; Shaked, Natan T

    2013-11-01

    We present a method for adding molecular specificity to wide-field interferometric phase microscopy (IPM) by recording the phase signatures of gold nanoparticles (AuNPs) labeling targets of interest in biological cells. The AuNPs are excited by time-modulated light at a wavelength corresponding to their absorption spectral peak, evoking a photothermal (PT) effect due to their plasmonic resonance. This effect induces a local temperature rise, resulting in local refractive index and phase changes that can be detected optically. Using a wide-field interferometric phase microscope, we acquired an image sequence of the AuNP sample phase profile without requiring lateral scanning, and analyzed the time-dependent profile of the entire field of view using a Fourier analysis, creating a map of the locations of AuNPs in the sample. The system can image a wide-field PT phase signal from a cluster containing down to 16 isolated AuNPs. AuNPs are then conjugated to epidermal growth factor receptor (EGFR) antibodies and inserted to an EGFR-overexpressing cancer cell culture, which is imaged using IPM and verified by confocal microscopy. To the best of our knowledge, this is the first time wide-field interferometric PT imaging is performed at the subcellular level without the need for total internal reflection effects or scanning.

  8. PAU-SA: A Synthetic Aperture Interferometric Radiometer Test Bed for Potential Improvements in Future Missions

    Directory of Open Access Journals (Sweden)

    Merce Vall-llosera

    2012-06-01

    Full Text Available The Soil Moisture and Ocean Salinity (SMOS mission is an Earth Explorer Opportunity mission from the European Space Agency (ESA. Its goal is to produce global maps of soil moisture and ocean salinity using the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS. The purpose of the Passive Advanced Unit Synthetic Aperture (PAU-SA instrument is to study and test some potential improvements that could eventually be implemented in future missions using interferometric radiometers such as the Geoestacionary Atmosferic Sounder (GAS, the Precipitation and All-weather Temperature and Humidity (PATH and the Geostationary Interferometric Microwave Sounder (GIMS. Both MIRAS and PAU-SA are Y-shaped arrays with uniformly distributed antennas, but the receiver topology and the processing unit are quite different. The purpose of this work is to identify the elements in the MIRAS’s design susceptible of improvement and apply them in the PAU-SA instrument demonstrator, to test them in view of these future interferometric radiometer missions.

  9. PAU-SA: A Synthetic Aperture Interferometric Radiometer Test Bed for Potential Improvements in Future Missions

    Science.gov (United States)

    Ramos-Perez, Isaac; Camps, Adriano; Bosch-Lluis, Xavi; Rodriguez-Alvarez, Nereida; Valencia-Domènech, Enric; Park, Hyuk; Forte, Giuseppe; Vall-llosera, Merce

    2012-01-01

    The Soil Moisture and Ocean Salinity (SMOS) mission is an Earth Explorer Opportunity mission from the European Space Agency (ESA). Its goal is to produce global maps of soil moisture and ocean salinity using the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS). The purpose of the Passive Advanced Unit Synthetic Aperture (PAU-SA) instrument is to study and test some potential improvements that could eventually be implemented in future missions using interferometric radiometers such as the Geoestacionary Atmosferic Sounder (GAS), the Precipitation and All-weather Temperature and Humidity (PATH) and the Geostationary Interferometric Microwave Sounder (GIMS). Both MIRAS and PAU-SA are Y-shaped arrays with uniformly distributed antennas, but the receiver topology and the processing unit are quite different. The purpose of this work is to identify the elements in the MIRAS's design susceptible of improvement and apply them in the PAU-SA instrument demonstrator, to test them in view of these future interferometric radiometer missions. PMID:22969371

  10. MART-type CT algorithms for the reconstruction of multidirectional interferometric data

    Science.gov (United States)

    Verhoeven, Dean D.

    1992-01-01

    There has been much recent interest in the application of optical tomography to the study of transport phenomena and chemical reactions in transparent fluid flows. An example is the use of multidirectional holographic interferometry and computed tomography for the study of crystal growth from solution under microgravity conditions. A critical part of any such measurement system is the computed tomography program used to convert the measured interferometric data to refractive index distributions in the object under study. Several of the most promising CT algorithms for this application are presented and compared here. Because of the practical difficulty of making multidirectional interferometric measurements, these measurements generally provide only limited amounts of data. Recent studies have indicated that of the several classes of reconstruction algorithms applicable in the limited-data situation, those based on the Multiplicative Algebraic Reconstruction Technique (MART) are the fastest, most flexible, and most accurate. Several MART-type algorithms have been proposed in the literature. In this paper we compare the performance of state-of-the-art implementations of four such algorithms under conditions of interest to those reconstructing multidirectional interferometric data. The algorithms are tested using numerically-generated data from two phantom objects, with two levels of added noise and with two different imaging geometries. A reconstruction of real data from a multidirectional holographic interferometer using the best of the algorithms is shown.

  11. Interferometric Astrometry with Hubble Space Telescope - A Review

    Science.gov (United States)

    Benedict, G. F.; McArthur, B. E.; Franz, O. G.; Wasserman, L. H.; Henry, T. J.; Takato, T.; Strateva, I.

    2000-05-01

    We review recent results from fringe tracking (POS) and fringe scanning (TRANS) mode astrometry using Fine Guidance Sensor 3 aboard Hubble Space Telescope. The relatively large field of regard, faint limiting magnitude, and raw resolution of FGS 3 have allowed us to obtain sub-millisecond of arc precision parallaxes for several Cataclysmic Variables ( RW Tri & TV Col), a fundamental distance scale calibrator (RR Lyr), a Planetary Nebula central star (NGC 6853), and a hot White Dwarf binary (Feige 24). We have determined parallaxes, orbital parameters, and masses for low-mass binaries critical to the lower main sequence Mass-Luminosity Relationship (Gl 791.2, Wolf 1062, Gl 623). The Astrometry Science Team presently consists of W. H. Jefferys, P.I., G. F. Benedict, Deputy P.I., B. McArthur, O.G. Franz, L. H. Wasserman, L. W. Fredrick, W. van Altena, E. Nelan, R. Duncombe, P. J. Shelus, and P. D. Hemenway. This research had the support of NASA Grants NAS5-1603 (GSFC), and GO-06036.01-94A, GO-07491.01-97A (STScI).

  12. Global carbon monoxide vertical distributions from spaceborne high-resolution FTIR nadir measurements

    OpenAIRE

    B. Barret; Turquety, S.; Hurtmans, D; Clerbaux, C.; Hadji-Lazaro, J.; I. Bey; Auvray, M.; P.-F. Coheur

    2005-01-01

    This paper presents the first global distributions of CO vertical profiles retrieved from a thermal infrared FTS working in the nadir geometry. It is based on the exploitation of the high resolution and high quality spectra measured by the Interferometric Monitor of Greenhouse gases (IMG) which flew onboard the Japanese ADEOS platform in 1996-1997. The retrievals are performed with an algorithm based on the Optimal Estimation Method (OEM) and are characterized in terms of vertical sensitivity...

  13. High resolution imaging detectors and applications

    CERN Document Server

    Saha, Swapan K

    2015-01-01

    Interferometric observations need snapshots of very high time resolution of the order of (i) frame integration of about 100 Hz or (ii) photon-recording rates of several megahertz (MHz). Detectors play a key role in astronomical observations, and since the explanation of the photoelectric effect by Albert Einstein, the technology has evolved rather fast. The present-day technology has made it possible to develop large-format complementary metal oxide–semiconductor (CMOS) and charge-coupled device (CCD) array mosaics, orthogonal transfer CCDs, electron-multiplication CCDs, electron-avalanche photodiode arrays, and quantum-well infrared (IR) photon detectors. The requirements to develop artifact-free photon shot noise-limited images are higher sensitivity and quantum efficiency, reduced noise that includes dark current, read-out and amplifier noise, smaller point-spread functions, and higher spectral bandwidth. This book aims to address such systems, technologies and design, evaluation and calibration, control...

  14. Unary resolution

    DEFF Research Database (Denmark)

    Aubert, Clément; Bagnol, Marc; Seiller, Thomas

    2016-01-01

    We give a characterization of deterministic polynomial time computation based on an algebraic structure called the resolution semiring, whose elements can be understood as logic programs or sets of rewriting rules over first-order terms. This construction stems from an interactive interpretation ...

  15. Interferometric and numerical study of the temperature field in the boundary layer and heat transfer in subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Lucic, Anita; Emans, Maximilian; Mayinger, Franz; Zenger, Christoph

    2004-04-01

    An interferometric study and a numerical simulation are presented of the combined process of the bulk turbulent convection and the dynamic of a vapor bubble which is formed in the superheated boundary layer of a subcooled flowing liquid, in order to determine the heat transfer to the flowing subcooled liquid. In this investigation focus has been given on a single vapor bubble at a defined cavity site to provide reproducible conditions. In the experimental study single bubbles were generated at a single artificial cavity by means of a CO{sub 2}-laser as a spot heater at a uniformly heated wall of a vertical rectangular channel with water as the test fluid. The experiments were performed at various degrees of subcooling and mass flow rates. The bubble growth and the temporal decrease of the bubble volume were captured by means of the high-speed cinematography. The thermal boundary layer and the temperature field at the phase-interface between fluid and bubble were visualized by means of the optical measurement method holographic interferometry with a high temporal and spatial resolution, and thus the local and temporal heat transfer could be quantified. The experimental results form a significant data basis for the description of the mean as well as the local heat transfer as a function of the flow conditions. According to the experimental configuration and the obtained data the numerical simulations were performed. A numerical method has been developed to simulate the influence of single bubbles on the surrounding fluid which is based on a Lagrangian approach to describe the motion of the bubbles. The method is coupled to a large-eddy simulations by the body force term which is locally evaluated based on the density field. The obtained experimental data correspond well with the numerical predictions, both of which demonstrate the thermo- and fluiddynamic characteristics of the interaction between the vapor bubble and the subcooled liquid.

  16. Using a low-noise interferometric fiber optic gyro in a pointing, acquisition, and tracking system

    Science.gov (United States)

    Kaufmann, John; Hakimi, Farhad; Boroson, Don

    2013-03-01

    Heritage pointing, acquisition, and tracking (PAT) systems have relied on optical tracking with a cooperative remote terminal to stabilize the line-of-sight of optical communications links. A hybrid approach, using new interferometric fiberoptic gyro (IFOG) technology to sense and correct local angular disturbances, blended with optical tracking, is shown to yield two significant advantages over traditional all-optical tracking: (1) line-of-sight stabilization over a very wide disturbance frequency range, down to extremely low frequencies (architect an optimal hybrid IFOG/optical PAT system. In addition, flow-down benefits that can simplify PAT system hardware will be discussed.

  17. Detection and characterization of single nanoparticles by interferometric phase modulated ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Barroso, F.; Bosch, S.; Tort, N.; Arteaga, O. [Universitat de Barcelona, IN2UB, Dep. Fisica Aplicada i Optica, c/Marti i Franques 1, 08028 (Spain); Sancho-Parramon, J. [Rudjer Boskovic Institute, Bijenicka c. 54, Zagreb 10002 (Croatia); Jover, E.; Bertran, E. [Universitat de Barcelona, IN2UB, Dep. Fisica Aplicada i Optica, c/Marti i Franques 1, 08028 (Spain); Canillas, A., E-mail: acanillas@ub.ed [Universitat de Barcelona, IN2UB, Dep. Fisica Aplicada i Optica, c/Marti i Franques 1, 08028 (Spain)

    2011-02-28

    We introduce a new measurement system called Nanopolar interferometer devoted to monitor and characterize single nanoparticles which is based on the interferometric phase modulated ellipsometry technique. The system collects the backscattered light by the particles in the solid angle subtended by a microscope objective and then analyses its frequency components. The results for the detection of 2 {mu}m and 50 nm particles are explained in terms of a cross polarization effect of the polarization vectors when the beam converts from divergent to parallel in the microscope objective. This explanation is supported with the results of the optical modelling using the exact Mie theory for the light scattered by the particles.

  18. Precision Laser Development for Interferometric Space Missions NGO, SGO, and GRACE Follow-On

    Science.gov (United States)

    Numata, Kenji; Camp, Jordan

    2011-01-01

    Optical fiber and semiconductor laser technologies have evolved dramatically over the last decade due to the increased demands from optical communications. We are developing a laser (master oscillator) and optical amplifier based on those technologies for interferometric space missions, including the gravitational-wave missions NGO/SGO (formerly LISA) and the climate monitoring mission GRACE Follow-On, by fully utilizing the matured wave-guided optics technologies. In space, where simpler and more reliable system is preferred, the wave-guided components are advantageous over bulk, crystal-based, free-space laser, such as NPRO (Nonplanar Ring Oscillator) and bulk-crystal amplifier.

  19. Evaluation of the internal field in lithium niobate ferroelectric domains by an interferometric method

    Science.gov (United States)

    de Angelis, M.; De Nicola, S.; Finizio, A.; Pierattini, G.; Ferraro, P.; Grilli, S.; Paturzo, M.

    2004-10-01

    We report on the evaluation of internal electric field of a ferroelectric engineered-domain in a LiNbO3 wafer crystal by detecting optical path length variation with a noninvasive interferometric inspection method. The lithium niobate wafer has been patterned and subjected to electric field poling to obtain two antiparallel ferroelectric domains separated by a single domain wall. The crystal has been mounted into one arm of a Mach-Zehnder-type interferometer to study the phase map and evaluate the effects of domain reversion by a digital holographic technique. Evaluation of the internal field and consequent variation of the electro-optical properties of the different domains is analyzed.

  20. Partially Filled Aperture Interferometric Telescopes: Achieving Large Aperture and Coronagraphic Performance

    Science.gov (United States)

    Moretto, G.; Kuhn, J.; Langlois, M.; Berdugyna, S.; Tallon, M.

    2017-09-01

    Telescopes larger than currently planned 30-m class instruments must break the mass-aperture scaling relationship of the Keck-generation of multi-segmented telescopes. Partially filled aperture, but highly redundant baseline interferometric instruments may achieve both large aperture and high dynamic range. The PLANETS FOUNDATION group has explored hybrid telescope-interferometer concepts for narrow-field optical systems that exhibit coronagraphic performance over narrow fields-of-view. This paper describes how the Colossus and Exo-Life Finder telescope designs achieve 10x lower moving masses than current Extremely Large Telescopes.

  1. Spatial chirp revisited: matrix analysis of dispersionless optical systems and correct interferometric autocorrelation

    Science.gov (United States)

    Dimitrov, Nikolay; Chakarov, Nedyalko; Dreischuh, Alexander

    2008-12-01

    In this work, by using 4x4 ray-pulse matrices, we analyze the influence of the position of the output diffraction grating in 4f- and 2f-2f-systems with respect to the eventually introduced group-delay dispersion, spatial and angular chirp. We show that in the 4f-configuration, in contrast to the 2f-2f-setup, the grating offset does not cause angular chirp and pulse front tilt. We theoretically derive an expression for the interferometric autocorrelation signal in the presence of an arbitrary pulse-front tilt.

  2. Interferometric characterization of a sub-wavelength near-infrared negative index metamaterial.

    Science.gov (United States)

    Zhang, Xuhuai; Davanço, Marcelo; Maller, Kara; Jarvis, Thomas W; Wu, Chihhui; Fietz, Chris; Korobkin, Dmitriy; Li, Xiaoqin; Shvets, Gennady; Forrest, Stephen R

    2010-08-16

    Negative phase advance through a single layer of near-IR negative index metamaterial (NIM) is identified through interferometric measurements. The NIM unit cell, sub-wavelength in both the lateral and light propagation directions, is comprised of a pair of Au strips separated by two dielectric and one Au film. Numerical simulations show that the negative phase advance through the single-layer sample is consistent with the negative index exhibited by a bulk material comprised of multiple layers of the same structure. We also numerically demonstrate that the negative index band persists in the lossless limit.

  3. Study of terahertz intensity dependence on time resolved dynamic fringes in the interferometric autocorrelation setup

    Science.gov (United States)

    Venkatesh, M.; Chaudhary, A. K.

    2014-10-01

    Terahertz signal is generated from Low temperature gallium arsenide photoconductive dipole antennas (gap = 5μm, length = 20μm) by focusing 15 fs laser pulses and applying 12V DC across it. Terahertz intensity is detected by Pyroelectric detector (THZ1.5MB-USB). The collinear autocorrelation arrangement provides dynamic fringes which are allowed to be incident on photoconductive antennas to study the variation in terahertz intensity with respect to delay between laser pulses. Interestingly, the profile of THz intensity variation was similar to interferometric autocorrelation signal of laser pulses. The THz power attenuation with its propagation distance in atmosphere was measured.

  4. Spatially resolved small-angle noncollinear interferometric autocorrelation of ultrashort pulses with microaxicon arrays.

    Science.gov (United States)

    Grunwald, R; Griebner, U; Nibbering, E T; Kummrow, A; Rini, M; Elsaesser, T; Kebbel, V; Hartmann, H J; Jüptner, W

    2001-11-01

    Small-angle, noncollinear, first- and second-order interferometric autocorrelation experiments with Ti:sapphire laser pulses of 9-80-fs duration have been performed with microaxicon arrays. Predictions of short-pulse spatial frequency effects were verified by comparison of interference patterns of single elements and matrices. An angular spectrum of Gaussian-shaped axicons was analyzed on the basis of linear refraction. Experimental data indicate contributions to autocorrelation by nonlinear refraction and travel-time differences. The influence of the spectral bandwidth was separated from the pulse-duration-dependent effects. Spatially resolved information about the coherence time was delivered by the multichannel structure.

  5. Non-interferometric, non-iterative phase retrieval by Green's functions.

    Science.gov (United States)

    Frank, Johannes; Altmeyer, Stefan; Wernicke, Guenther

    2010-10-01

    In this paper a non-interferometric, non-iterative method for phase retrieval by Green's functions is presented. The theory is based on the parabolic wave equation that describes propagation of light in the Fresnel approximation in homogeneous media. Green's first identity will be used to derive an algorithm for phase retrieval considering different boundary conditions. Finally it will be shown that a commonly used solution of the transport-of-intensity equation can be obtained as a special case of the more general Green's function formulation derived here.

  6. Three-dimensional Reconstruction Method Study Based on Interferometric Circular SAR

    Directory of Open Access Journals (Sweden)

    Hou Liying

    2016-10-01

    Full Text Available Circular Synthetic Aperture Radar (CSAR can acquire targets’ scattering information in all directions by a 360° observation, but a single-track CSAR cannot efficiently obtain height scattering information for a strong directive scatter. In this study, we examine the typical target of the three-dimensional circular SAR interferometry theoryand validate the theory in a darkroom experiment. We present a 3D reconstruction of the actual tank metal model of interferometric CSAR for the first time, verify the validity of the method, and demonstrate the important potential applications of combining 3D reconstruction with omnidirectional observation.

  7. Dynamic Strain Measured by Mach-Zehnder Interferometric Optical Fiber Sensors

    Directory of Open Access Journals (Sweden)

    Shiuh-Chuan Her

    2012-03-01

    Full Text Available Optical fibers possess many advantages such as small size, light weight and immunity to electro-magnetic interference that meet the sensing requirements to a large extent. In this investigation, a Mach-Zehnder interferometric optical fiber sensor is used to measure the dynamic strain of a vibrating cantilever beam. A 3 × 3 coupler is employed to demodulate the phase shift of the Mach-Zehnder interferometer. The dynamic strain of a cantilever beam subjected to base excitation is determined by the optical fiber sensor. The experimental results are validated with the strain gauge.

  8. Phase measurements of erythrocytes affected by metal ions with quantitative interferometric microscopy

    Science.gov (United States)

    Wang, Shouyu; Yan, Keding; Shan, Yanke; Xu, Mingfei; Liu, Fei; Xue, Liang

    2015-12-01

    Erythrocyte morphology is an important factor in disease diagnosis, however, traditional setups as microscopes and cytometers cannot provide enough quantitative information of cellular morphology for in-depth statistics and analysis. In order to capture variations of erythrocytes affected by metal ions, quantitative interferometric microscopy (QIM) is applied to monitor their morphology changes. Combined with phase retrieval and cell recognition, erythrocyte phase images, as well as phase area and volume, can be accurately and automatically obtained. The research proves that QIM is an effective tool in cellular observation and measurement.

  9. An interferometer for high-resolution optical surveillance from geostationary orbit

    Science.gov (United States)

    Bonino, L.; Bresciani, F.; Piasini, G.; Flebus, C.; Lecat, J.-H.; Roose, S.; Pisani, M.; Cabral, A.; Rebordão, J.; Proença, C.; Costal, J.; Lima, P. U.; Loix, N.; Musso, F.

    2017-11-01

    The activities described in this paper have been developed in the frame of the EUCLID CEPA 9 RTP 9.9 "High Resolution Optical Satellite Sensor" project of the WEAO Research Cell. They have been focused on the definition of an interferometric instrument optimised for the high-resolution optical surveillance from geostationary orbit (GEO) by means of the synthetic aperture technique, and on the definition and development of the related enabling technologies. In this paper we describe the industrial team, the selected mission specifications and overview of the whole design and manufacturing activities performed.

  10. Development Status of Adjustable X-Ray Optics with 0.5 Arcsecond Resolution

    Science.gov (United States)

    Reid, P. B.; ODell, Stephen; Elsner, Ron; Ramsey, Brian; Gubarev, Misha; Aldcroft, T.; Allured, R.; Cotroneo, V.; Johnson-Wilke, R. L.; McMuldroch, S.; hide

    2014-01-01

    We report on the continuing development of adjustable, grazing incidence X-ray optics for 0.5 arcsec telescopes. Adjustable X-ray optics offer the potential for achieving sub-arcsecond imaging resolution while sufficiently thin and light-weight to constitute a mirror assembly with several square meters collecting area. The adjustable mirror concept employs a continuous thin film of piezoelectric material deposited on the back of the paraboloid and hyperboloid mirror segments. Individually addressable electrodes on the piezoelectric layer allow the introduction of deformations in localized "cells" which are used to correct mirror figure errors resulting from fabrication, mounting and aligning the thin mirrors, residual gravity release and temperature changes. We describe recent results of this development. These include improving cell yield to approx. 100 per cent, measurements of hysteresis and stability, comparisons of modeled and measured behavior, simulations of mirror performance, and the development and testing of conical Wolter- I mirror segments. We also present our plans going forward toward the eventual goal of achieving TRL 6 prior to the 2020 Decadal Review.

  11. Mitigation of defocusing by statics and near-surface velocity errors by interferometric least-squares migration

    KAUST Repository

    Sinha, Mrinal

    2015-08-19

    We propose an interferometric least-squares migration method that can significantly reduce migration artifacts due to statics and errors in the near-surface velocity model. We first choose a reference reflector whose topography is well known from the, e.g., well logs. Reflections from this reference layer are correlated with the traces associated with reflections from deeper interfaces to get crosscorrelograms. These crosscorrelograms are then migrated using interferometric least-squares migration (ILSM). In this way statics and velocity errors at the near surface are largely eliminated for the examples in our paper.

  12. Microgravity vertical gradient measurement in the site of VIRGO interferometric antenna (Pisa plain, Italy

    Directory of Open Access Journals (Sweden)

    F. Fidecaro

    2008-06-01

    Full Text Available The site of the European Gravitational Observatory (EGO located in the countryside near Pisa (Tuscany, Italy was investigated by a microgravity vertical gradient (MVG survey. The EGO site houses the VIRGO interferometric antenna for gravitational waves detection. The microgravity survey aims to highlight the gravity anomalies of high-frequency related to more superficial geological sources in order to obtain a detailed model of the lithologic setting of the VIRGO site, that will allow an estimate of the noise induced by seismic waves and by Newtonian interference. This paper presents the results of the gradiometric survey of 2006 in the area of the interferometric antenna. MVG measurements allow us to enhance the high frequency signal strongly associated with the shallow structures. The gradient gravity map shows a main negative pattern that seems related to the trending of the high density layer of gravel that was evidenced in geotechnical drillings executed along the orthogonal arms during the construction of the VIRGO complex. Calibrating the relationship between the vertical gradient and the depth of the gravel interface we have computed a model of gravity gradient for the whole VIRGO site, defining the 3D distribution of the top surface of this layer. This latter shows a NE-SW negative pattern that may represent a palaeo-bed alluvial of the Serchio from the Bientina River system.

  13. Filtering of Interferometric SAR Phase Images as a Fuzzy Matching-Pursuit Blind Estimation

    Directory of Open Access Journals (Sweden)

    Luciano Alparone

    2005-12-01

    Full Text Available We present an original application of fuzzy logic to restoration of phase images from interferometric synthetic aperture radar (InSAR, which are affected by zero-mean uncorrelated noise, whose variance depends on the underlying coherence, thereby yielding a nonstationary random noise process. Spatial filtering of the phase noise is recommended, either before phase unwrapping is accomplished, or simultaneously with it. In fact, phase unwrapping basically relies on a smoothness constraint of the phase field, which is severely hampered by the noise. Space-varying linear MMSE estimation is stated as a problem of matching pursuit, in which the estimator is obtained as an expansion in series of a finite number of prototype estimators, fitting the spatial features of the different statistical classes encountered, for example, fringes and steep slope areas. Such estimators are calculated in a fuzzy fashion through an automatic training procedure. The space-varying coefficients of the expansion are stated as degrees of fuzzy membership of a pixel to each of the estimators. Neither a priori knowledge on the noise variance is required nor particular signal and noise models are assumed. Filtering performances on simulated phase images show a steady SNR improvement over conventional box filtering. Applications of the proposed filter to interferometric phase images demonstrate a superior ability of restoring fringes yet preserving their discontinuities, together with an effective noise smoothing performance, irrespective of locally varying coherence characteristics.

  14. Lower frequency companions for the Advanced LIGO gravitational wave interferometric detectors: an observational opportunity?

    Energy Technology Data Exchange (ETDEWEB)

    DeSalvo, Riccardo [California Institute of Technology, LIGO Project, Pasadena, CA 91125 (United States)

    2004-03-07

    Recent x-ray and optical observations provide evidence for a population of intermediate mass black holes with masses of tens to thousands of solar masses. Dynamical braking in high stellar density regions may 'catalyze' the inspiral of heavy mass objects down to the million-year time scale. Black-hole binaries, with the masses implied by the observations, will plunge below 100 Hz. It may be technologically possible to build ground-based low frequency gravitational wave interferometric detectors optimized to detect these events and install them next to Advanced LIGO (AdL), within the existing LIGO facilities. This additional interferometer, operated coherently with AdL and Virgo, would greatly enhance the effectiveness of the existing interferometers by generating a wealth of triggers for potentially frequent but otherwise undetectable heavy mass inspirals. AdL would study, at higher frequency, the triggered, ultra-relativistic phases (merging and ringdown) of these inspirals. Comparisons are made between the expected detection performances of AdL in its proposed wide band tuning, as well as AdL in its best low frequency tuning, with a low frequency gravitational wave interferometric detector that is mechanically and optically optimized for operation at the lowest possible frequency. Finally, the synergies of tandem operation of AdL and the proposed low frequency interferometer have been considered.

  15. Interferometric SAR monitoring of the Vallcebre landslide (Spain using corner reflectors

    Directory of Open Access Journals (Sweden)

    M. Crosetto

    2013-04-01

    Full Text Available This paper describes the deformation monitoring of the Vallcebre landslide (Eastern Pyrenees, Spain using the Differential Interferometric Synthetic Aperture Radar (DInSAR technique and corner reflectors (CRs. The fundamental aspects of this satellite-based deformation monitoring technique are described to provide the key elements needed to fully understand and correctly interpret its results. Several technical and logistic aspects related to the use of CRs are addressed including an analysis of the suitability of DInSAR data to monitor a specific landslide, a discussion on the choice of the type of CRs, suggestions for the installation of CRs and a description of the design of a CR network. This is followed by the description of the DInSAR data analysis procedure required to derive deformation estimates starting from the main observables of the procedure, i.e., the interferometric phases. The main observation equation is analysed, discussing the role of each phase component. A detailed discussion is devoted to the phase unwrapping problem, which has a direct impact on the deformation monitoring capability. Finally, the performance of CRs for monitoring ground displacements has been tested in the Vallcebre landslide (Eastern Pyrenees, Spain. Two different periods, which provide interesting results to monitor over time the kinematics of different parts of the considered landslide unit, are analysed and described.

  16. DYNAMIC PARAMETERS ESTIMATION OF INTERFEROMETRIC SIGNALS BASED ON SEQUENTIAL MONTE CARLO METHOD

    Directory of Open Access Journals (Sweden)

    M. A. Volynsky

    2014-05-01

    Full Text Available The paper deals with sequential Monte Carlo method applied to problem of interferometric signals parameters estimation. The method is based on the statistical approximation of the posterior probability density distribution of parameters. Detailed description of the algorithm is given. The possibility of using the residual minimum between prediction and observation as a criterion for the selection of multitude elements generated at each algorithm step is shown. Analysis of input parameters influence on performance of the algorithm has been conducted. It was found that the standard deviation of the amplitude estimation error for typical signals is about 10% of the maximum amplitude value. The phase estimation error was shown to have a normal distribution. Analysis of the algorithm characteristics depending on input parameters is done. In particular, the influence analysis for a number of selected vectors of parameters on evaluation results is carried out. On the basis of simulation results for the considered class of signals, it is recommended to select 30% of the generated vectors number. The increase of the generated vectors number over 150 does not give significant improvement of the obtained estimates quality. The sequential Monte Carlo method is recommended for usage in dynamic processing of interferometric signals for the cases when high immunity is required to non-linear changes of signal parameters and influence of random noise.

  17. Validation of Forested Inundation Extent Revealed by L-Band Polarimetric and Interferometric SAR Data

    Science.gov (United States)

    Chapman, Bruce; Celi, Jorge; Hamilton, Steve; McDonald, Kyle

    2013-01-01

    UAVSAR, NASA's airborne Synthetic Aperture Radar (SAR), conducted an extended observational campaign in Central and South America in March 2013, primarily related to volcanic deformations along the Andean Mountain Range but also including a large number of flights studying other scientific phenomena. During this campaign, the L-Band SAR collected data over the Napo River in Ecuador. The objectives of this experiment were to acquire polarimetric and interferometric L-Band SAR data over an inundated tropical forest in Ecuador simultaneously with on-the-ground field work ascertaining the extent of inundation, and to then derive from this data a quantitative estimate for the error in the SAR-derived inundation extent. In this paper, we will first describe the processing and preliminary analysis of the SAR data. The polarimetric SAR data will be classified by land cover and inundation state. The interferometric SAR data will be used to identify those areas where change in inundation extent occurred, and to measure the change in water level between two observations separated by a week. Second, we will describe the collection of the field estimates of inundation, and have preliminary comparisons of inundation extent measured in the field field versus that estimated from the SAR data.

  18. Optimization of Positioning of Interferometric Array Antennas Using Division Algorithm for Radio Astronomy Applications

    Science.gov (United States)

    Kiehbadroudinezhad, Shahideh; Valente, Daniela; Cada, Michael; Kamariah Noordin, Nor; Shahabi, Adib

    2017-10-01

    The Square Kilometre Array (SKA) ushers in the new generation of large radio telescopes that will work at wavelengths between meters and centimeters. In order to competitively design interferometric antenna arrays such as SKA, it is crucial to focus on the optimization of system performance. In this paper, we contribute to the solution by introducing a new optimization algorithm called Division Algorithm (DA). This algorithm finds the optimal positions of antennas to simultaneously maximize u-v coverage and decrease sidelobe level (SLL). The DA is able to optimize the configuration of the interferometric array in both snapshot and Earth rotation synthesis observations. To demonstrate its efficiency, the DA is applied to configure an optimum 30-element array for the Giant Metrewave Radio Telescope. The proposed algorithm is able to improve the overlapped samples parameter by about 4% and the unsampled cells parameter by about 12%, at snapshot observation, compared to the Genetic Algorithm (GA). DA is able to improve these two parameters for a 6-hr tracking observation as well. Finally, the proposed algorithm is compared with the GA for different source declination. Results show that the DA is able to decrease the SLL better than the GA.

  19. Interferometric adaptive optics for high power laser pointing, wave-front control and phasing

    Energy Technology Data Exchange (ETDEWEB)

    Baker, K L; Stappaerts, E A; Homoelle, D C; Henesian, M A; Bliss, E S; Siders, C W; Barty, C J

    2009-01-21

    Implementing the capability to perform fast ignition experiments, as well as, radiography experiments on the National Ignition Facility (NIF) places stringent requirements on the control of each of the beam's pointing and overall wavefront quality. One quad of the NIF beams, 4 beam pairs, will be utilized for these experiments and hydrodynamic and particle-in-cell simulations indicate that for the fast ignition experiments, these beams will be required to deliver 50% (4.0 kJ) of their total energy (7.96 kJ) within a 40 {micro}m diameter spot at the end of a fast ignition cone target. This requirement implies a stringent pointing and overall phase conjugation error budget on the adaptive optics system used to correct these beam lines. The overall encircled energy requirement is more readily met by phasing of the beams in pairs but still requires high Strehl ratios, Sr, and rms tip/tilt errors of approximately one {micro}rad. To accomplish this task we have designed an interferometric adaptive optics system capable of beam pointing, high Strehl ratio and beam phasing with a single pixilated MEMS deformable mirror and interferometric wave-front sensor. We present the design of a testbed used to evaluate the performance of this wave-front sensor below along with simulations of its expected performance level.

  20. Optical birefringence and molecular orientation of crazed fibres utilizing the phase shifting interferometric technique

    Science.gov (United States)

    Sokkar, T. Z. N.; El-Farahaty, K. A.; El-Bakary, M. A.; Omar, E. Z.; Hamza, A. A.

    2017-09-01

    In this article, the features of the phase shifting interferometric technique were utilized to investigate the effect of the presence of crazes in both outer and inner layers on optical birefringence and molecular orientation of polypropylene fibres. The Pluta polarizing interference microscope was used as a phase shifting technique. This method includes adding a stepper motor with a control unit to the micrometer screw of the Pluta microscope. This optical system was calibrated to be used as a phase shifting interferometric technique. The advantage of this technique is that it can detect the crazes in both inner and outer layers of the sample under test. Via this method, the relation between the presence of the crazes (in both inner and outer layers) and the optical molecular orientation of polypropylene (PP) fibres was demonstrated. To clarify the role of this method, the spatial carrier frequency technique was used to show the effect of the presence of the crazes only in the outer layers on the phase distribution values and hence the structural properties of PP fibres.

  1. Non-Interferometric Tomography of Phase Objects Using Spatial Light Modulators

    Directory of Open Access Journals (Sweden)

    Thanh Nguyen

    2016-10-01

    Full Text Available Quantitative 3D phase retrieval techniques are based on either interferometric techniques such as holography or noninterferometric intensity-based techniques such as the transport of intensity equation (TIE. Interferometric techniques are vibration-sensitive and often use a reference beam requiring complicated optical alignment. In this work we develop a simple, fast, and noninterferometric tomographic 3D phase retrieval technique based on the TIE which does not suffer from such drawbacks. The optical setup is a modified 4f TIE system which uses an SLM to replace the slow translation of the CCD required to record several diffraction patterns in a traditional TIE system. This novel TIE setup is suitable for dynamical events such as imaging biological processes. A rotating mechanical stage is constructed to obtain tomographic phase images of the object. The tomographic reconstruction algorithm is based on the Fourier slice theorem (backprojection algorithm which applies to objects with a small refractive index span. Simulation and experimental results are shown as part of this work. A graphical user interface is developed to perform the TIE tomographic reconstruction algorithm and to synchronize the captured intensities by the CCD, the phase patterns displayed on the SLM, and the Arduino controlled rotating stage assembly.

  2. Real time self-mixing interferometric laser sensor for embedded applications

    Science.gov (United States)

    Zabit, Usman; Bernal, Olivier D.; Bosch, Thierry

    2013-12-01

    We present a Self-Mixing (SM) interferometric laser displacement sensor that is capable of providing correct target measurements in real time, even when it is subject to extraneous parasitic movements. The sensor achieves such robustness by using an embedded MEMS Solid -State Accelerometer (SSA) that has been coupled with the laser sensor. The SSA thus measures the extraneous movement acting on the laser s ensor and this information is used to provide correct sensing. The proposed SSA-SM sensing system uses Consecutive-Samples based Unwrapping (CSU) to process the SM interferometric signal while a Digital Signal Processor (DSP) takes care of band-pass filtering, double integration as well as phase and gain corrections needed for the acceleration signal. Hence, a compact, real-time, precise and self-aligned SSA-SM sensor has been designed that has a displacement measurement precision of approximately 100 nm with a parasitic movement elimination of 31dB for a laser diode emitting at 785 nm.

  3. Gap Resolution

    Energy Technology Data Exchange (ETDEWEB)

    2017-04-25

    Gap Resolution is a software package that was developed to improve Newbler genome assemblies by automating the closure of sequence gaps caused by repetitive regions in the DNA. This is done by performing the follow steps:1) Identify and distribute the data for each gap in sub-projects. 2) Assemble the data associated with each sub-project using a secondary assembler, such as Newbler or PGA. 3) Determine if any gaps are closed after reassembly, and either design fakes (consensus of closed gap) for those that closed or lab experiments for those that require additional data. The software requires as input a genome assembly produce by the Newbler assembler provided by Roche and 454 data containing paired-end reads.

  4. High resolution interferometry as a tool for characterization of swelling of weakly charged hydrogels subjected to amphiphile and cyclodextrin exposure

    OpenAIRE

    Gao, Ming; Gawel, Kamila; Stokke, Bjørn Torger

    2013-01-01

    A high resolution interferometric technique was used to determine swelling behavior of weakly charged polyacrylamide hydrogels in the presence of oppositely charged surfactants and subsequent exposure to cyclodextrins. Hydrogels of copolymerized acrylamide and 2-acrylamido-2-methyl-1-propanesulfonic acid (0.22, 0.44, 0.88 mol%) and crosslinked with bisacrylamide (3, 6, 12 mol%) were employed. The equilibrium swelling and swelling kinetics of the hydrogels were determined with 2 nanometer reso...

  5. Nondestructive testing by using long-wave infrared interferometric techniques with CO2 lasers and microbolometer arrays.

    Science.gov (United States)

    Alexeenko, Igor; Vandenrijt, Jean-François; Pedrini, Giancarlo; Thizy, Cédric; Vollheim, Birgit; Osten, Wolfgang; Georges, Marc P

    2013-01-01

    We describe three different interferometric techniques (electronic speckle pattern interferometry, digital holographic interferometry, and digital shearography), using a long-wave infrared radiation produced by a CO(2) laser and recorded on a microbolometer array. Experimental results showing how these methods can be used for nondestructive testing are presented. Advantages and disadvantages of these approaches are discussed.

  6. Continuous monitoring of biophysical Eucalyptus sp. parameters using interferometric synthetic aperture radar data in P and X bands

    Science.gov (United States)

    Gama, Fábio Furlan; dos Santos, João Roberto; Mura, José Claudio

    2016-04-01

    This work aims to verify the applicability of models obtained using interferometric synthetic aperture radar (SAR) data for estimation of biophysical Eucalyptus saligna parameters [diameter of breast height (DBH), total height and volume], as a method of continuous forest inventory. In order to obtain different digital elevation models, and the interferometric height (Hint) to retrieve the tree heights, SAR surveying was carried out by an airborne interferometric SAR in two frequencies X and P bands. The study area, located in the Brazilian southeast region (S 22°53‧22″/W 45°26‧16″ and S 22°53‧22″/W 45°26‧16″), comprises 128.64 hectares of Eucalyptus saligna stands. The methodological procedures encompassed: forest inventory, topographic surveying, radar mapping, radar processing, and multivariable regression techniques to build Eucalyptus volume, DBH, and height models. The statistical regression pointed out Hint and interferometric coherence as the most important variables for the total height and DBH estimation; for the volume model, however, only the Hint variable was selected. The performance of the biophysical models from the second campaign, two years later (2006), were consistent and its results are very promising for updating annual inventories needed for managing Eucalyptus plantations.

  7. All-solid birefringent hybrid photonic crystal fiber based interferometric sensor for measurement of strain and temperature

    DEFF Research Database (Denmark)

    Gu, Bobo; Yuan, Scott Wu; Zhang, A. Ping

    2011-01-01

    A highly sensitive fiber-optic interferometric sensor based on an all-solid birefringent hybrid photonic crystal fiber (PCF) is demonstrated for measuring strain and temperature. A strain sensitivity of similar to 23.8 pm/mu epsilon and a thermal sensitivity of similar to-1.12 nm/degrees C...

  8. Interferometric X-Ray Imaging of Breast Cancer Specimens at 51 keV X-Ray Energy

    Science.gov (United States)

    Takeda, Tohoru; Wu, Jin; Tsuchiya, Yoshinori; Yoneyama, Akio; Lwin, Thet Thet; Aiyoshi, Yuji; Zeniya, Tsutomu; Hyodo, Kazuyuki; Ueno, Ei

    2004-08-01

    The feasibility of the interferometric X-ray imaging technique is examined for revealing the features of breast cancer specimens. The interferometric X-ray imaging system consisted of an asymmetrically cut silicon crystal, a monolithic X-ray interferometer, a phase-shifter, an object cell, and an X-ray CCD camera. Ten 10-mm-thick formalin-fixed breast cancer specimens were imaged at 51 keV, and these images were compared with absorption-contrast X-ray images obtained at 18 keV monochromatic synchrotron X-ray. The interferometric X-ray images clearly depicted the essential features of the breast cancer such as microcalcification down to a size of 0.036 mm, spiculation, and detailed inner soft tissue structures closely matched with histopathological morphology, while the absorption-contrast X-ray images obtained using nearly the same X-ray dose only resolved microcalcification down to a size of 0.108 mm and spiculation. The interferometric X-ray imaging technique can be considered to be an innovative technique for the early and accurate diagnosis of breast cancer using an extremely low X-ray dose.

  9. Modeling and design of a spiral-shaped Mach-Zehnder interferometric sensor for refractive index sensing of watery solutions

    NARCIS (Netherlands)

    Hoekman, M.; Dijkstra, Marcel; Dijkstra, Mindert; Hoekstra, Hugo

    2006-01-01

    The modeling and design of a spiral-shaped Mach-Zehnder Interferometric sensor (sMZI sensor) for refractive index sensing of watery solutions is presented. The goal of the running project is to realise a multi-sensing array by placing multiple sMZIs in series to form a sensing branch, and to place

  10. LSPR and Interferometric Sensor Modalities Combined Using a Double-Clad Optical Fiber

    Directory of Open Access Journals (Sweden)

    Harald Ian Muri

    2018-01-01

    Full Text Available We report on characterization of an optical fiber-based multi-parameter sensor concept combining localized surface plasmon resonance (LSPR signal and interferometric sensing using a double-clad optical fiber. The sensor consists of a micro-Fabry-Perot in the form of a hemispherical stimuli-responsive hydrogel with immobilized gold nanorods on the facet of a cleaved double-clad optical fiber. The swelling degree of the hydrogel is measured interferometrically using the single-mode inner core, while the LSPR signal is measured using the multi-mode inner cladding. The quality of the interferometric signal is comparable to previous work on hydrogel micro-Fabry-Perot sensors despite having gold nanorods immobilized in the hydrogel. We characterize the effect of hydrogel swelling and variation of bulk solution refractive index on the LSPR peak wavelength. The results show that pH-induced hydrogel swelling causes only weak redshifts of the longitudinal LSPR mode, while increased bulk refractive index using glycerol and sucrose causes large blueshifts. The redshifts are likely due to reduced plasmon coupling of the side-by-side configuration as the interparticle distance increases with increasing swelling. The blueshifts with increasing bulk refractive index are likely due to alteration of the surface electronic structure of the gold nanorods donated by the anionic polymer network and glycerol or sucrose solutions. The recombination of biotin-streptavidin on gold nanorods in hydrogel showed a 7.6 nm redshift of the longitudinal LSPR. The LSPR response of biotin-streptavidin recombination is due to the change in local refractive index (RI, which is possible to discriminate from the LSPR response due to changes in bulk RI. In spite of the large LSPR shifts due to bulk refractive index, we show, using biotin-functionalized gold nanorods binding to streptavidin, that LSPR signal from gold nanorods embedded in the anionic hydrogel can be used for label

  11. Multi-temporal interferometric monitoring of ground deformations in Haiti with COSMO/SkyMed HIMAGE data

    Science.gov (United States)

    Nutricato, R.; Wasowski, J.; Chiaradia, M.; Piard, B. E.; Généa, S.

    2013-12-01

    The catastrophic Mw=7.0 shallow earthquake of 12 January 2010 that struck Haiti have led to numerous studies focused on the geodynamics of the region. In particular, the co-seismic fault mechanism of the 2010 Haiti earthquake as well as post-seismic deformations have been investigated through SAR interferometry (InSAR) techniques, thanks to the availability of satellite SAR sensors operating in different radar bands (ENVISAT ASAR, ALOS PALSAR, TerraSAR-X, COSMO/SkyMed). Moreover, advanced multitemporal SAR interferometry (MTI) based on COSMO/SkyMED (CSK) data is well suited for the detection and monitoring of post-seismic ground or structural instabilities. Indeed, with its short revisit time (up to 4 days) CSK allows building interferometric stacks much faster than previous satellite missions, like ERS/ENVISAT. Here we report the first outcomes of the MTI investigation based on high resolution (3 m) CSK data, conducted in the framework of a scientific collaboration between the Centre National de l'Information Géo-Spatiale (CNIGS) of Haiti and the Department of Physics (DIF) of the University of Bari, Italy. We rely on a stack of 89 CSK data (image mode: HIMAGE; polarization: HH; look side: right; pass direction: ascending; beam: H4-0A) acquired by the Italian Space Agency (ASI) over the Port-au-Prince (PaP) metropolitan and surrounding areas that were severely hit by the 2010 earthquake. CSK acquisitions span the period June 2011 ÷ February 2013, which is sufficient for detecting and monitoring significant ground instabilities. The MTI results were obtained through the application of the SPINUA processing chain, a Persistent Scatterers Interferometry (PSI)-like technique. In particular, we detected significant subsidence phenomena affecting river deltas and coastal areas of the PaP and Carrefour region. The maximum rate of subsidence movements exceed few cm/yr and this implies increasing flooding (or tsunami) hazard. Furthermore, maximum subsidence rates were

  12. A new method to extract forest height from repeat-pass polarimetric and interferometric radar data

    Science.gov (United States)

    Lavalle, M.; Hensley, S.; Dubayah, R.

    2012-12-01

    The objective of this paper is to present a new remote sensing method and a new physical model that will potentially enable estimating forest height and vegetation 3D structure using radar technology. The method is based on repeat-pass polarimetric-interferometric radar technique; the model is termed random-motion-over-ground (RMoG) model [1, 2]. We will describe a step-by-step procedure that will help the ecosystem community to monitor ecosystems at regional and global scale using radar data available from the forthcoming radar missions. We will show first results of forest height estimated from UAVSAR data and compared against LVIS data. We will quantify the error associated to our method. We will also discuss the improvements that we plan on including in future works. Our ultimate goal is to measure low and large biomass stocks using the large amount of radar data that will be available in the near future. The Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) is a fully polarimetric L-band airborne radar developed at the Jet Propulsion Laboratory (JPL). UAVSAR acquires repeat-pass interferometric data for measuring vegetation structure and monitoring crustal deformations. The UAVSAR team at JPL has acquired and processed several polarimetric-interferometric (Pol-InSAR) datasets over the Harvard Forest in Massachusetts (United States) that allows testing repeat-pass Pol-InSAR technique. Pol-InSAR technique was proposed 15 years ago to estimate vegetation biomass and overcome the inherent saturation of radar backscatter versus biomass [3]. The advantage of Pol-InSAR is the ability to estimate the 3D structure of vegetation using a small number of interferometric acquisitions. In order to extract vegetation properties from Pol-InSAR UAVSAR data, we use a model of temporal-volumetric coherence, the RMoG model, suitable for repeat-pass interferometry. In the RMoG model the vegetation is idealized as a two-layer scattering scenario constituted by a

  13. Interferometric Measurement of the Current-Phase Relationship of a Superfluid Weak Link

    Directory of Open Access Journals (Sweden)

    S. Eckel

    2014-09-01

    Full Text Available Weak connections between superconductors or superfluids can differ from classical links due to quantum coherence, which allows flow without resistance. Transport properties through such weak links can be described with a single function, the current-phase relationship, which serves as the quantum analog of the current-voltage relationship. Here, we present a technique for inteferometrically measuring the current-phase relationship of superfluid weak links. We interferometrically measure the phase gradient around a ring-shaped superfluid Bose-Einstein condensate containing a rotating weak link, allowing us to identify the current flowing around the ring. While our Bose-Einstein condensate weak link operates in the hydrodynamic regime, this technique can be extended to all types of weak links (including tunnel junctions in any phase-coherent quantum gas. Moreover, it can also measure the current-phase relationships of excitations. Such measurements may open new avenues of research in quantum transport.

  14. Interferometric phase microscopy using slightly-off-axis reflective point diffraction interferometer

    Science.gov (United States)

    Bai, Hongyi; Zhong, Zhi; Shan, Mingguang; Liu, Lei; Guo, Lili; Zhang, Yabin

    2017-03-01

    An interferometric phase microscopy (IPM) is proposed using slightly-off-axis reflective point diffraction interferometry for quantitative phase imaging. A retro-reflector consisting two mirrors is used to generate an angle between the object beam and reference beam, and a 45° tilted polarizing beam splitter is used to split the horizontal and vertical components of the both beams. Two carrier interferograms with π/2 phase-shift can be acquired in one shot, and the phase distribution of a thin specimen can be retrieved using a fast reconstruction method. The new IPM without loss in the utilization of the input-plane field of view combines the real time and optimizing detector bandwidth measurement benefit associated with slightly-off-axis method, high stability associated with common path geometry, and simplicity in terms of procedure and setup. Experiments are carried out on both static and dynamic specimens to demonstrate the validity and stability of the proposed method.

  15. Group index dispersion of holey fibres measured by a white-light spectral interferometric technique

    Science.gov (United States)

    Hlubina, P.; Ciprian, D.; Chlebus, R.

    2008-08-01

    We present a new white-light interferometric technique to measure the group index of holey fibres over a wide wavelength range. The technique utilizes an unbalanced Mach-Zehnder interferometer with a fibre under test of known length placed in one of the interferometer arms and the other arm with adjustable path length. In a first step, the differential group index of the fibre is measured over a wide wavelength range. In a second step, the fibre is replaced by the reference sample of known thickness and group dispersion to determine precisely the group index of the fibre at one specific wavelength. The group index as a function of wavelength is measured for two different holey fibres, one made of pure silica glass and the other made of SK222 glass. For both fibres, the wavelength dependence of the group index of the outer cladding and modes supported by the fibre is measured.

  16. Loop topology based white light interferometric fiber optic sensor network for application of perimeter security

    Science.gov (United States)

    Yuan, Libo; Dong, Yongtao

    2011-09-01

    A loop topology based white light interferometric sensor network for perimeter security has been designed and demonstrated. In the perimeter security sensing system, where fiber sensors are packaged in the suspended cable or buried cable, a bi-directional optical path interrogator is built by using Michelson or Mach-Zehnder interferometer. A practical implementation of this technique is presented by using an amplified spontaneous emission (ASE) light source and standard single mode fiber, which are common in communication industry. The sensor loop topology is completely passive and absolute length measurements can be obtained for each sensing fiber segment so that it can be used to measure quasi-distribution strain perturbation. For the long distance perimeter monitoring, this technique not only extends the multiplexing potential, but also provides a redundancy for the sensing system. One breakdown point is allowed in the sensor loop because the sensing system will still work even if the embedded sensor loop breaks somewhere.

  17. Thin walled Nb tubes for suspending test masses in interferometric gravitational wave detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.H. [School of Physics, University of Western Australia, Crawley 6009, WA (Australia)]. E-mail: bhl@physics.uwa.edu.au; Ju, L. [School of Physics, University of Western Australia, Crawley 6009, WA (Australia); Blair, D.G. [School of Physics, University of Western Australia, Crawley 6009, WA (Australia)

    2006-02-13

    In a previous Letter, we have shown that the use of orthogonal ribbons could provide a better mirror suspension technique in interferometric gravitational wave antennas. One of the key improvements presented by the orthogonal ribbon is the reduction in the number of violin string modes in the direction of the laser. We have considered more elaborate geometries in recent simulations and obtained a suspension that provides further reduction in the number of violin string modes in the direction of the laser, as well as in the direction orthogonal to the laser. This thin walled niobium tube suspension exhibits a reduction in the number of violin modes to 5 in each direction up to a frequency of 5 kHz. Furthermore, the violin mode thermal noise peaks can be reduced in amplitude by 30 dB.

  18. Characterization of the room temperature payload prototype for the cryogenic interferometric gravitational wave detector KAGRA.

    Science.gov (United States)

    Peña Arellano, Fabián Erasmo; Sekiguchi, Takanori; Fujii, Yoshinori; Takahashi, Ryutaro; Barton, Mark; Hirata, Naoatsu; Shoda, Ayaka; van Heijningen, Joris; Flaminio, Raffaele; DeSalvo, Riccardo; Okutumi, Koki; Akutsu, Tomotada; Aso, Yoichi; Ishizaki, Hideharu; Ohishi, Naoko; Yamamoto, Kazuhiro; Uchiyama, Takashi; Miyakawa, Osamu; Kamiizumi, Masahiro; Takamori, Akiteru; Majorana, Ettore; Agatsuma, Kazuhiro; Hennes, Eric; van den Brand, Jo; Bertolini, Alessandro

    2016-03-01

    KAGRA is a cryogenic interferometric gravitational wave detector currently under construction in the Kamioka mine in Japan. Besides the cryogenic test masses, KAGRA will also rely on room temperature optics which will hang at the bottom of vibration isolation chains. The payload of each chain comprises an optic, a system to align it, and an active feedback system to damp the resonant motion of the suspension itself. This article describes the performance of a payload prototype that was assembled and tested in vacuum at the TAMA300 site at the NAOJ in Mitaka, Tokyo. We describe the mechanical components of the payload prototype and their functionality. A description of the active components of the feedback system and their capabilities is also given. The performance of the active system is illustrated by measuring the quality factors of some of the resonances of the suspension. Finally, the alignment capabilities offered by the payload are reported.

  19. Interferometric technique for nanoscale dynamics of fluid drops on arbitrary substrates

    Science.gov (United States)

    Verma, Gopal; Pandey, Mrityunjay; Singh, Kamal P.

    2015-07-01

    We demonstrate a simple interferometric probe to detect nanoscale dynamics of sessile fluid drops on arbitrary rough or flexible substrates. The technique relies on producing high-contrast Newton-ring like dynamical fringes by interference between a weak Fresnel reflection from the air-fluid interface of the drop and an air-glass interface of a convex lens placed above the drop in quasi-normal geometry. By analyzing the dynamical fringes, we observed 100-700 nm/s fluctuations in water drops evaporating on metal, leaves, insect wing, and sand paper due to their surface roughness. Similar fluctuations were also observed during spreading of non-volatile glycerin drops on various rough surfaces. Another application of the technique is demonstrated in precision measurement of change in evaporation rate of a water drop due to cooling of a metal substrate. This technique can be further miniaturized with a microscope objective with potential for wide applications.

  20. Advancement of an Interferometric Flow Velocity Measurement Technique by Adaptive Optics

    Science.gov (United States)

    Büttner, Lars; Leithold, Christoph; Czarske, Jürgen

    2014-01-01

    Flow measurements often take place under difficult conditions. Optical flow measurement techniques are affected by variations of the refractive index, caused e.g., by temperature, concentration, or pressure gradients. This will give rise to an increased measurement uncertainty or cause the measurement to fail. To overcome these limitations, we propose the employment of adaptive optics. In this contribution we present interferometric flow velocity measurements through a fluctuating air-water interface by the use of adaptive optics. Using the adaptive optics, the rate of valid measurement signals can be improved from 28% to 83%. The results are promising to enable measurements in difficult environments affected by refractive index variations which were not accessible so far.

  1. Modeling and de-embedding the interferometric scanning microwave microscopy by means of dopant profile calibration

    Energy Technology Data Exchange (ETDEWEB)

    Michalas, L., E-mail: loukas.michalas@artov.imm.cnr.it; Marcelli, R. [National Research Council, Institute for Microelectronics and Microsystems (CNR-IMM), Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Wang, F.; Brillard, C.; Theron, D. [Institut d' Electronique, de Microélectronique et de Nanotechnologie, CNRS UMR 8520/University of Lille 1, Avenue Poincaré, CS 60069, 59652 Villeneuve d' Ascq (France); Chevalier, N.; Hartmann, J. M. [Univ. Grenoble Alpes, F-38000 Grenoble, France and CEA, LETI, MINATEC Campus, F-38054 Grenoble (France)

    2015-11-30

    This paper presents the full modeling and a methodology for de-embedding the interferometric scanning microwave microscopy measurements by means of dopant profile calibration. A Si calibration sample with different boron-doping level areas is used to that end. The analysis of the experimentally obtained S{sub 11} amplitudes based on the proposed model confirms the validity of the methodology. As a specific finding, changes in the tip radius between new and used tips have been clearly identified, leading to values for the effective tip radius in the range of 45 nm to 85 nm, respectively. Experimental results are also discussed in terms of the effective area concept, taking into consideration details related to the nature of tip-to-sample interaction.

  2. Interferometric autocorrelation of an attosecond pulse train in the single-cycle regime.

    Science.gov (United States)

    Nabekawa, Yasuo; Shimizu, Toshihiko; Okino, Tomoya; Furusawa, Kentaro; Hasegawa, Hirokazu; Yamanouchi, Kaoru; Midorikawa, Katsumi

    2006-10-13

    We report on the direct observation of the phase locking of the attosecond pulse train (APT) via interferometric autocorrelation in the extreme ultraviolet region. APT is formed with Fourier synthesis of high-order harmonic fields of a femtosecond laser pulse. Time-of-flight mass spectra of N+, resulting from the Coulomb explosion of N2 absorbing two photons of APT, efficiently yield correlated signals of APT. The measured autocorrelation trace exhibits that the duration of the pulse should be only 1.3 periods of the extreme ultraviolet carrier frequency. A few interference fringes within the short pulse duration clearly show two types of symmetry, which ensure the phase locking between pulses in APT.

  3. Characterization of a broadband interferometric autocorrelator for visible light with ultrashort blue laser pulses

    Science.gov (United States)

    Zürch, M.; Hoffmann, A.; Gräfe, M.; Landgraf, B.; Riediger, M.; Spielmann, Ch.

    2014-06-01

    We present a compact interferometric autocorrelator that allows the characterization of ultrashort laser pulses in the visible light domain (370-740 nm). The presented device uses a GaN photodiode with corresponding two-photon absorption. Different GaN and AlGaN photodiodes were characterized for this purpose. Despite AlGaN diodes have a better matched bandgap for this application, we have found that only the GaN diodes show sufficient nonlinear behavior. Using the autocorrelator we were able to characterize ultrashort frequency doubled Ti:Sapphire laser pulses with a pulse duration down to 18 fs in the second harmonic having just a few hundred nanojoules of pulse energy. The broadband behavior and extension towards the UV along with the need for only low energetic pulses are the novelties of this device.

  4. Imaging the noncentrosymmetric structural organisation of tissue with Interferometric Second Harmonic Generation microscopy

    CERN Document Server

    Rivard, Maxime; Laliberte, Mathieu; Bertrand-Grenier, Antony; Martin, Francois; Pepin, Henri; Pfeffer, Christian P; Brown, Cameron; Rammuno, Lora; Legare, Francois

    2012-01-01

    We report the imaging of tendon, a connective tissue rich in collagen type I proteins, with Interferometric Second Harmonic Generation (I-SHG) microscopy. We observed that the noncentrosymmetric structural organization can be maintained along the fibrillar axis over more than 150 {\\mu}m, while in the transverse direction it is ~1-15 {\\mu}m. Those results are explained by modeling tendon as a heterogeneous distribution of noncentrosymmetric nanocylinders (collagen fibrils) oriented along the fibrillar axis. The preservation of the noncentrosymmetric structural organization over multiple tens of microns reveals that tendon is made of domains in which the fraction occupied by fibrils oriented in one direction is larger than in the other.

  5. Optical interferometric synthesis of PAM4 signals based on dual-drive Mach-Zehnder modulation

    Science.gov (United States)

    Xu, Jianfeng; Du, Jiangbing; Ren, Rongrong; Ruan, Zhengshang; He, Zuyuan

    2017-11-01

    In this work, optical interferometric synthesis and demodulation of four-level pulse amplitude modulation (PAM4) signals by using commercial dual-drive Mach-Zehnder Modulator (DD-MZM) is proposed and studied. Simulations are carried out and signal quality is evaluated in terms of eye jitter, linearity and so on for the PAM4 signals generated by the proposed DD-MZM with improved performance unfolded. Experimental generation of the optically synthesized PAM4 signals up to 50 Gbaud (100 Gbps) is achieved. The transmission of the PAM4 signals over 5-Km standard single mode fiber (SSMF) is carried out with error-free below the FEC limit (3.8E-3) without digital equalization at 90 Gbps. The linear-amplifier-free configuration by DD-MZM leads to simplified implementation and improved performance for high speed PAM4 signal generation, which would be of great significance for short reach optical interconnection.

  6. Electro-Optic Swept Source Based on AOTF for Wavenumber-Linear Interferometric Sensing and Imaging

    Directory of Open Access Journals (Sweden)

    Ga-Hee Han

    2016-04-01

    Full Text Available We demonstrate a novel electro-optic swept source for wavenumber-linear interferometric sensing and imaging applications. The electro-optic swept source based on an acousto-optic tunable filter (AOTF provides high environmental stability and arbitrary drive function sweeping because the electro-optic wavelength selection does not depend on a mechanical moving component to tune the output lasing wavelength. We show improved stability of the suggested electro-optic swept source, compared to a conventional swept source based on a fiber Fabry–Perot tunable filter (FFP-TF. Various types of wavelength sweeping are demonstrated by applying the programmed drive function to the applied radio frequency (RF of the AOTF. We demonstrated improved image quality of optical coherence tomography (OCT by using the wavenumber-linear drive function of a simple triangular signal, which has a high wavenumber-linearity with an R-square value of 0.99991.

  7. Blind calibration of radio interferometric arrays using sparsity constraints and its implications for self-calibration

    Science.gov (United States)

    Chiarucci, Simone; Wijnholds, Stefan J.

    2018-02-01

    Blind calibration, i.e. calibration without a priori knowledge of the source model, is robust to the presence of unknown sources such as transient phenomena or (low-power) broad-band radio frequency interference that escaped detection. In this paper, we present a novel method for blind calibration of a radio interferometric array assuming that the observed field only contains a small number of discrete point sources. We show the huge computational advantage over previous blind calibration methods and we assess its statistical efficiency and robustness to noise and the quality of the initial estimate. We demonstrate the method on actual data from a Low-Frequency Array low-band antenna station showing that our blind calibration is able to recover the same gain solutions as the regular calibration approach, as expected from theory and simulations. We also discuss the implications of our findings for the robustness of regular self-calibration to poor starting models.

  8. Interferometric methods for the characterization of photosensitive and nonlinear optical materials

    Science.gov (United States)

    Yavrian, Artashes

    Dans cette these nous presentons d'abord nos etudes des proprietes photoinduites dans les polymeres dopes avec colorant azoique. Nous avons demontre experimentalement que l'onde optique polarisee circulairement induit aussi bien un axe d'anisotropie dans ces materiaux que l'onde polarisee lineairement. Les processus a deux couleurs ont ete etudies et utilises pour l'amelioration significative de la qualite d'une image enregistree holographiquement dans ces polymeres. Les coefficients non lineaires de l'indice de refraction et d'absorption des echantillons frais et vieillis ont ete mesures en utilisant la technique de z-scan. Le role du vieillissement de la matrice polymerique durant ces mesures a ete etudie. Nous avons aussi propose et realise experimentalement une nouvelle technique interferometrique-ayant-une excellente-stabilite-mecanique. La non-linearite optique des polymeres dopes avec les colorants azoique et des crystaux liquides a ete mesuree avec cet interferometre.

  9. Mach-Zehnder interferometric photonic crystal fiber for low acoustic frequency detections

    Energy Technology Data Exchange (ETDEWEB)

    Pawar, Dnyandeo; Rao, Ch. N.; Kale, S. N., E-mail: sangeetakale2004@gmail.com [Department of Applied Physics, Defence Institute of Advanced Technology (DU), Girinagar, Pune 411 025, Maharashtra (India); Choubey, Ravi Kant [Department of Applied Physics, Amity Institute of Applied Sciences, Amity University, Noida 201 313 (India)

    2016-01-25

    Low frequency under-water acoustic signal detections are challenging, especially for marine applications. A Mach-Zehnder interferometric hydrophone is demonstrated using polarization-maintaining photonic-crystal-fiber (PM-PCF), spliced between two single-mode-fibers, operated at 1550 nm source. These data are compared with standard hydrophone, single-mode and multimode fiber. The PM-PCF sensor shows the highest response with a power shift (2.32 dBm) and a wavelength shift (392.8 pm) at 200 Hz. High birefringence values and the effect of the imparted acoustic pressure on this fiber, introducing the difference between the fast and slow axis changes, owing to the phase change in the propagation waves, demonstrate the strain-optic properties of the sensor.

  10. Interferometric Reflectance Imaging Sensor (IRIS—A Platform Technology for Multiplexed Diagnostics and Digital Detection

    Directory of Open Access Journals (Sweden)

    Oguzhan Avci

    2015-07-01

    Full Text Available Over the last decade, the growing need in disease diagnostics has stimulated rapid development of new technologies with unprecedented capabilities. Recent emerging infectious diseases and epidemics have revealed the shortcomings of existing diagnostics tools, and the necessity for further improvements. Optical biosensors can lay the foundations for future generation diagnostics by providing means to detect biomarkers in a highly sensitive, specific, quantitative and multiplexed fashion. Here, we review an optical sensing technology, Interferometric Reflectance Imaging Sensor (IRIS, and the relevant features of this multifunctional platform for quantitative, label-free and dynamic detection. We discuss two distinct modalities for IRIS: (i low-magnification (ensemble biomolecular mass measurements and (ii high-magnification (digital detection of individual nanoparticles along with their applications, including label-free detection of multiplexed protein chips, measurement of single nucleotide polymorphism, quantification of transcription factor DNA binding, and high sensitivity digital sensing and characterization of nanoparticles and viruses.

  11. Range-resolved interferometric signal processing using sinusoidal optical frequency modulation.

    Science.gov (United States)

    Kissinger, Thomas; Charrett, Thomas O H; Tatam, Ralph P

    2015-04-06

    A novel signal processing technique using sinusoidal optical frequency modulation of an inexpensive continuous-wave laser diode source is proposed that allows highly linear interferometric phase measurements in a simple, self-referencing setup. Here, the use of a smooth window function is key to suppress unwanted signal components in the demodulation process. Signals from several interferometers with unequal optical path differences can be multiplexed, and, in contrast to prior work, the optical path differences are continuously variable, greatly increasing the practicality of the scheme. In this paper, the theory of the technique is presented, an experimental implementation using three multiplexed interferometers is demonstrated, and detailed investigations quantifying issues such as linearity and robustness against instrument drift are performed.

  12. Fully interferometric controllable anomalous refraction efficiency using cross modulation with plasmonic metasurfaces.

    Science.gov (United States)

    Liu, Zhaocheng; Chen, Shuqi; Li, Jianxiong; Cheng, Hua; Li, Zhancheng; Liu, Wenwei; Yu, Ping; Xia, Ji; Tian, Jianguo

    2014-12-01

    We present a method of fully interferometric, controllable anomalous refraction efficiency by introducing cross-modulated incident light based on plasmonic metasurfaces. Theoretical analyses and numerical simulations indicate that the anomalous and ordinary refracted beams generated from two opposite-helicity incident beams and following the generalized Snell's law will have a superposition for certain incident angles, and the anomalous refraction efficiency can be dynamically controlled by changing the relative phase of the incident sources. As the incident wavelength nears the resonant wavelength of the plasmonic metasurfaces, two equal-amplitude incident beams with opposite helicity can be used to control the anomalous refraction efficiency. Otherwise, two unequal-amplitude incident beams with opposite helicity can be used to fully control the anomalous refraction efficiency. This Letter may offer a further step in the development of controllable anomalous refraction.

  13. Super-virtual Interferometric Separation and Enhancement of Back-scattered Surface Waves

    KAUST Repository

    Guo, Bowen

    2015-08-19

    Back-scattered surface waves can be migrated to detect near-surface reflectors with steep dips. A robust surface-wave migration requires the prior separation of the back-scattered surface-wave events from the data. This separation is often difficult to implement because the back-scattered surface waves are masked by the incident surface waves. We mitigate this problem by using a super-virtual interferometric method to enhance and separate the back-scattered surface waves. The key idea is to calculate the virtual back-scattered surface waves by stacking the resulting virtual correlated and convolved traces associated with the incident and back-scattered waves. Stacking the virtual back-scattered surface waves improves their signal-to-noise ratio and separates the back-scattered surface-waves from the incident field. Both synthetic and field data results validate the robustness of this method.

  14. Method for suppressing the bias drift of interferometric all-fiber optic gyroscopes.

    Science.gov (United States)

    Wang, Xinyue; He, Changhong; Wang, Ziyu

    2011-04-01

    We propose a simple and, to our knowledge, novel method for suppressing the bias drift of interferometric all-fiber optic gyroscopes (I-FOGs) and for self-calibrating the bias of I-FOGs to zero. Using a square wave to reverse the polarity of the sinusoidal voltage on a piezoelectric (PZT) modulator periodically, and calculating the output signal of a demodulator circuit in-phase with the square wave by a digital signal processor (DSP), we successfully reduce the bias drift of I-FOGs. Experimental results show that, at room temperature, the proposed method dramatically reduces the bias instability of an I-FOG from 0.201 deg/h to 0.102 deg/h. With this method, the I-FOGs no longer need zero calibration.

  15. Symmetry evaluation for an interferometric fiber optic gyro coil utilizing a bidirectional distributed polarization measurement system.

    Science.gov (United States)

    Peng, Feng; Li, Chuang; Yang, Jun; Hou, Chengcheng; Zhang, Haoliang; Yu, Zhangjun; Yuan, Yonggui; Li, Hanyang; Yuan, Libo

    2017-07-10

    We propose a dual-channel measurement system for evaluating the optical path symmetry of an interferometric fiber optic gyro (IFOG) coil. Utilizing a bidirectional distributed polarization measurement system, the forward and backward transmission performances of an IFOG coil are characterized simultaneously by just a one-time measurement. The simple but practical configuration is composed of a bidirectional Mach-Zehnder interferometer and multichannel transmission devices connected to the IFOG coil under test. The static and dynamic temperature results of the IFOG coil reveal that its polarization-related symmetric properties can be effectively obtained with high accuracy. The optical path symmetry investigation is highly beneficial in monitoring and improving the winding technology of an IFOG coil and reducing the nonreciprocal effect of an IFOG.

  16. Simultaneous time-space resolved reflectivity and interferometric measurements of dielectrics excited with femtosecond laser pulses

    Science.gov (United States)

    Garcia-Lechuga, M.; Haahr-Lillevang, L.; Siegel, J.; Balling, P.; Guizard, S.; Solis, J.

    2017-06-01

    Simultaneous time-and-space resolved reflectivity and interferometric measurements over a temporal span of 300 ps have been performed in fused silica and sapphire samples excited with 800 nm, 120 fs laser pulses at energies slightly and well above the ablation threshold. The experimental results have been simulated in the frame of a multiple-rate equation model including light propagation. The comparison of the temporal evolution of the reflectivity and the interferometric measurements at 400 nm clearly shows that the two techniques interrogate different material volumes during the course of the process. While the former is sensitive to the evolution of the plasma density in a very thin ablating layer at the surface, the second yields an averaged plasma density over a larger volume. It is shown that self-trapped excitons do not appreciably contribute to carrier relaxation in fused silica at fluences above the ablation threshold, most likely due to Coulomb screening effects at large excited carrier densities. For both materials, at fluences well above the ablation threshold, the maximum measured plasma reflectivity shows a saturation behavior consistent with a scattering rate proportional to the plasma density in this fluence regime. Moreover, for both materials and for pulse energies above the ablation threshold and delays in the few tens of picoseconds range, a simultaneous "low reflectivity" and "low transmission" behavior is observed. Although this behavior has been identified in the past as a signature of femtosecond laser-induced ablation, its origin is alternatively discussed in terms of the optical properties of a material undergoing strong isochoric heating, before having time to substantially expand or exchange energy with the surrounding media.

  17. Large-Actuator-Number Horizontal Path Correction of Atmospheric Turbulence utilizing an Interferometric Phase Conjugate Engine

    Energy Technology Data Exchange (ETDEWEB)

    Baker, K L; Stappaerts, E A; Gavel, D; Tucker, J; Silva, D A; Wilks, S C; Olivier, S S; Olsen, J

    2004-08-25

    An adaptive optical system used to correct horizontal beam propagation paths has been demonstrated. This system utilizes an interferometric wave-front sensor and a large-actuator-number MEMS-based spatial light modulator to correct the aberrations incurred by the beam after propagation along the path. Horizontal path correction presents a severe challenge to adaptive optics systems due to the short atmospheric transverse coherence length and the high degree of scintillation incurred by laser propagation along these paths. Unlike wave-front sensors that detect phase gradients, however, the interferometric wave-front sensor measures the wrapped phase directly. Because the system operates with nearly monochromatic light and uses a segmented spatial light modulator, it does not require that the phase be unwrapped to provide a correction and it also does not require a global reconstruction of the wave-front to determine the phase as required by gradient detecting wave-front sensors. As a result, issues with branch points are eliminated. Because the atmospheric probe beam is mixed with a large amplitude reference beam, it can be made to operate in a photon noise limited regime making its performance relatively unaffected by scintillation. The MEMS-based spatial light modulator in the system contains 1024 pixels and is controlled to speeds in excess of 800 Hz, enabling its use for correction of horizontal path beam propagation. In this article results are shown of both atmospheric characterization with the system and open loop horizontal path correction of a 1.53 micron laser by the system. To date Strehl ratios of greater than 0.5 have been achieved.

  18. Photothermal nanoparticles as molecular specificity agents in interferometric phase microscopy (Conference Presentation)

    Science.gov (United States)

    Shaked, Natan T.

    2017-02-01

    I review our latest advances in wide-field interferometric imaging of biological cells with molecular specificity, obtained by time-modulated photothermal excitation of gold nanoparticles. Heat emitted from the nanoparticles affects the measured phase signal via both the nanoparticle surrounding refractive-index and thickness changes. These nanoparticles can be bio-functionalized to bind certain biological cell components; thus, they can be used for biomedical imaging with molecular specificity, as new nanoscopy labels, and for photothermal therapy. Predicting the ideal nanoparticle parameters requires a model that computes the thermal and phase distributions around the particle, enabling more efficient phase imaging of plasmonic nanoparticles, and sparing trial and error experiments of using unsuitable nanoparticles. We thus developed a new model for predicting phase signatures from photothermal nanoparticles with arbitrary parameters. We also present a dual-modality technique based on wide-field photothermal interferometric phase imaging and simultaneous ablation to selectively deplete specific cell populations labelled by plasmonic nanoparticles. We experimentally demonstrated our ability to detect and specifically ablate in vitro cancer cells over-expressing epidermal growth factor receptors (EGFRs), labelled with plasmonic nanoparticles, in the presence of either EGFR under-expressing cancer cells or white blood cells. This demonstration established an initial model for depletion of circulating tumour cells in blood. The proposed system is able to image in wide field the label-free quantitative phase profile together with the photothermal phase profile of the sample, and provides the ability of both detection and ablation of chosen cells after their selective imaging.

  19. Squeezed light for the interferometric detection of high-frequency gravitational waves

    Science.gov (United States)

    Schnabel, R.; Harms, J.; Strain, K. A.; Danzmann, K.

    2004-03-01

    The quantum noise of the light field is a fundamental noise source in interferometric gravitational-wave detectors. Injected squeezed light is capable of reducing the quantum noise contribution to the detector noise floor to values that surpass the so-called standard quantum limit (SQL). In particular, squeezed light is useful for the detection of gravitational waves at high frequencies where interferometers are typically shot-noise limited, although the SQL might not be beaten in this case. We theoretically analyse the quantum noise of the signal-recycled laser interferometric gravitational-wave detector GEO 600 with additional input and output optics, namely frequency-dependent squeezing of the vacuum state of light entering the dark port and frequency-dependent homodyne detection. We focus on the frequency range between 1 kHz and 10 kHz, where, although signal recycled, the detector is still shot-noise limited. It is found that the GEO 600 detector with present design parameters will benefit from frequency-dependent squeezed light. Assuming a squeezing strength of -6 dB in quantum noise variance, the interferometer will become thermal noise limited up to 4 kHz without further reduction of bandwidth. At higher frequencies the linear noise spectral density of GEO 600 will still be dominated by shot noise and improved by a factor of 106dB/20dB ap 2 according to the squeezing strength assumed. The interferometer might reach a strain sensitivity of 6 × 10-23 above 1 kHz (tunable) with a bandwidth of around 350 Hz. We propose a scheme to implement the desired frequency-dependent squeezing by introducing an additional optical component into GEO 600's signal-recycling cavity.

  20. Deformation vector measurement by means of ground based interferometric radar system

    Science.gov (United States)

    Michelini, Alberto; Coppi, Francesco

    2017-10-01

    Ground Based Interferometric Radar (GBInRad) is a class of terrestrial remote sensing imaging system, based on microwave interferometric techniques. The principal application of GBInRad system is deformation monitoring, since respect to other techniques they can provide remote sensing, high sensitivity to small deformations, long range of measurements, imaging capability and fast scan time. The main limitation of standard GBInRad system is their capability of detecting movements only along the Line of Sight (LoS) of the sensor, although actual targets may show deformations in any direction of space; this represents an important limitation with respect to other techniques able to estimate the full 3D deformation vector. If the displacement direction is not known a priori, combining together LoS displacement measured from different spatial positions, it is possible to reconstruct the actual 3D displacement vector of monitored targets. In this paper are introduced and analysed the various aspect of the displacement vector measurement with multiple GBInRad system that work both in a monostatic and in a bistatic configuration. In the monostatic configuration every system transmits and receives the signal independently from the others; this approach requires multiple GBInRad system deployed to monitoring the same scenario and therefore its main limitations lie in the costs, power consumption and maintenance. A possible cost-effective evolution of the monostatic configuration is to exploit GBInRad system in a multiple bistatic configuration; a multiple bistatic Radar is a system in which a transmitter operates together with multiple receivers located in different positions in space. In this paper, the deformation vector measurement by means of bistatic GBInRad is proposed.

  1. A mid-IR interferometric survey with MIDI/VLTI: resolving the second-generation protoplanetary disks around post-AGB binaries

    Science.gov (United States)

    Hillen, M.; Van Winckel, H.; Menu, J.; Manick, R.; Debosscher, J.; Min, M.; de Wit, W.-J.; Verhoelst, T.; Kamath, D.; Waters, L. B. F. M.

    2017-03-01

    Aims: We present a mid-IR interferometric survey of the circumstellar environment of a specific class of post-asymptotic giant branch (post-AGB) binaries. For this class the presence of a compact dusty disk has been postulated on the basis of various spatially unresolved measurements. The aim is to determine the angular extent of the N-band emission directly and to resolve the compact circumstellar structures. Methods: Our interferometric survey was performed with the MIDI instrument on the VLTI. In total 19 different systems were observed using variable baseline configurations. Combining all the visibilities at a single wavelength at 10.7 μm, we fitted two parametric models to the data: a uniform disk and a ring model mimicking a temperature gradient. We compared our observables of the whole sample, with synthetic data computed from a grid of radiative transfer models of passively irradiated disks in hydrostatic equilibrium. These models are computed with a Monte Carlo code that has been widely applied to describe the structure of protoplanetary disks around young stellar objects (YSO). Results: The spatially resolved observations show that the majority of our targets cluster closely together in the distance-independent size-colour diagram, and have extremely compact N-band emission regions. The typical uniform disk diameter of the N-band emission region is 40 mas, which corresponds to a typical brightness temperature of 400-600 K. The resolved objects display very similar characteristics in the interferometric observables and in the spectral energy distributions. Therefore, the physical properties of the disks around our targets must be similar. Our results are discussed in the light of recently published sample studies of YSOs to compare quantitatively the secondary discs around post-AGB stars to the ones around YSOs. Conclusions: Our high-angular-resolution survey further confirms the disk nature of the circumstellar structures present around wide post

  2. Quantifying time-of-flight-resolved optical field dynamics in turbid media with interferometric near-infrared spectroscopy (iNIRS) (Conference Presentation)

    Science.gov (United States)

    Borycki, Dawid; Kholiqov, Oybek; Zhou, Wenjun; Srinivasan, Vivek J.

    2017-03-01

    Sensing and imaging methods based on the dynamic scattering of coherent light, including laser speckle, laser Doppler, and diffuse correlation spectroscopy quantify scatterer motion using light intensity (speckle) fluctuations. The underlying optical field autocorrelation (OFA), rather than being measured directly, is typically inferred from the intensity autocorrelation (IA) through the Siegert relationship, by assuming that the scattered field obeys Gaussian statistics. In this work, we demonstrate interferometric near-infrared spectroscopy (iNIRS) for measurement of time-of-flight (TOF) resolved field and intensity autocorrelations in fluid tissue phantoms and in vivo. In phantoms, we find a breakdown of the Siegert relationship for short times-of-flight due to a contribution from static paths whose optical field does not decorrelate over experimental time scales, and demonstrate that eliminating such paths by polarization gating restores the validity of the Siegert relationship. Inspired by these results, we developed a method, called correlation gating, for separating the OFA into static and dynamic components. Correlation gating enables more precise quantification of tissue dynamics. To prove this, we show that iNIRS and correlation gating can be applied to measure cerebral hemodynamics of the nude mouse in vivo using dynamically scattered (ergodic) paths and not static (non-ergodic) paths, which may not be impacted by blood. More generally, correlation gating, in conjunction with TOF resolution, enables more precise separation of diffuse and non-diffusive contributions to OFA than is possible with TOF resolution alone. Finally, we show that direct measurements of OFA are statistically more efficient than indirect measurements based on IA.

  3. Polarimetric and Interferometric Synthetic Aperture Radar (Pol-InSAR); a new way to quantify three-dimensional structure of Earth and planetary surfaces Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This study will employ a three phased approach: SAR image formation and calibration. DBSAR polarimetric and interferometric data analysis. PolInSAR algorithm...

  4. Tuning operating point of extrinsic Fabry-Perot interferometric fiber-optic sensors using microstructured fiber and gas pressure.

    Science.gov (United States)

    Tian, Jiajun; Zhang, Qi; Fink, Thomas; Li, Hong; Peng, Wei; Han, Ming

    2012-11-15

    Intensity-based demodulation of extrinsic Fabry-Perot interferometric (EFPI) fiber-optic sensors requires the light wavelength to be on the quadrature point of the interferometric fringes for maximum sensitivity. In this Letter, we propose a novel and remote operating-point tuning method for EFPI fiber-optic sensors using microstructured fibers (MFs) and gas pressure. We demonstrated the method using a diaphragm-based EFPI sensor with a microstructured lead-in fiber. The holes in the MF were used as gas channels to remotely control the gas pressure inside the Fabry-Perot cavity. Because of the deformation of the diaphragm with gas pressure, the cavity length and consequently the operating point can be remotely tuned for maximum sensitivity. The proposed operating-point tuning method has the advantage of reduced complexity and cost compared to previously reported methods.

  5. Atmospheric corrections in interferometric synthetic aperture radar surface deformation – a case study of the city of Mendoza, Argentina

    OpenAIRE

    S. Balbarani; Euillades, P. A.; Euillades, L. D.; Casu, F.; Riveros, N. C.

    2013-01-01

    Differential interferometry is a remote sensing technique that allows studying crustal deformation produced by several phenomena like earthquakes, landslides, land subsidence and volcanic eruptions. Advanced techniques, like small baseline subsets (SBAS), exploit series of images acquired by synthetic aperture radar (SAR) sensors during a given time span. Phase propagation delay in the atmosphere is the main systematic error of interferometric SAR measurements. It affects differently images ...

  6. Investigation of the Chromosphere-Corona Interface with the Upgraded Very high angular Resolution ULtraviolet Telescope (VAULT2.0) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a three-year effort to upgrade our existing sub-arcsecond Lyman-alpha telescope payload to improve the observing cadence by a factor of 2, increase the...

  7. High temperature millimeter wave radiometric and interferometric measurements of slag-refractory interaction for application to coal gasifiers

    Energy Technology Data Exchange (ETDEWEB)

    McCloy, John S.; Crum, Jarrod V.; Sundaram, S. K.; Slaugh, Ryan W.; Woskov, Paul P.

    2011-09-17

    Millimeter wave (MMW) radiometry can be used for simultaneous measurement of emissivity and temperature of materials under extreme environments (high temperature, pressure, and corrosive environments) such as in slagging coal gasifiers, where sensors have been identified as a key enabling technology need for process optimization. We present a state-of-the-art dual-channel MMW heterodyne radiometer with active interferometric capability that allows simultaneous radiometric measurements of sample temperature, emissivity, and flow dynamics to over 1873 K. Interferometric capability is supplied via a probe signal originating from the 137 GHz radiometer local oscillator (LO). The interferometric 'video' channels allow measurement of additional parameters simultaneously, such as volume expansion, thickness change, and slag viscosity along with temperature or emissivity. This capability has been used to demonstrate measurement of temperature and simulated coal slag infiltration into a chromia refractory brick sample as well as slag flow down a vertically placed refractory brick. Observed phenomena include slag melting and slumping, slag reboil and foam with oxygen evolution, and eventual failure of the alumina crucible through corrosion by the molten slag. These results show the promise of the MMW system for extracting quantitative and qualitative process parameters from operating slagging coal gasifiers, providing valuable information for process efficiency, control, and increased productivity.

  8. Fusion of Multi-Temporal Interferometric Coherence and Optical Image Data for the 2016 Kumamoto Earthquake Damage Assessment

    Directory of Open Access Journals (Sweden)

    Nopphawan Tamkuan

    2017-06-01

    Full Text Available Earthquakes are one of the most devastating types of natural disasters, and happen with little to no warning. This study combined Landsat-8 and interferometric ALOS-2 coherence data without training area techniques by classifying the remote sensing ratios of specific features for damage assessment. Waterbodies and highly vegetated areas were extracted by the modified normalized difference water index (MNDWI and normalized difference vegetation index (NDVI, respectively, from after-earthquake images in order to improve the accuracy of damage maps. Urban areas were classified from pre-event interferometric coherence data. The affected areas from the earthquake were detected with the normalized difference (ND between the pre- and co-event interferometric coherence. The results presented three damage types; namely, damage to buildings caused by ground motion, liquefaction, and landslides. The overall accuracy (94% of the confusion matrix was excellent. Results for urban areas were divided into three damage levels (e.g., none–slight, slight–heavy, heavy–destructive at a high (90% overall accuracy level. Moreover, data on buildings damaged by liquefaction and landslides were in good agreement with field survey information. Overall, this study illustrates an effective damage assessment mapping approach that can support post-earthquake management activities for future events, especially in areas where geographical data are sparse.

  9. Development of high resolution shearography device for non-destructive testing of composite materials

    Science.gov (United States)

    Burkov, Mikhail; Lyubutin, Pavel; Byakov, Anton; Panin, Sergey

    2015-10-01

    The paper presents the results of preliminary testing of high-resolution shearographic device and software for signal processing to be applied for non-destructive evaluation (NDE) of composite materials. Shearography is an interferometric non-contact NDT/E method that allows obtaining strain data straightly at video frame rate to diagnose different composite structures to provide the safe operation of the structure and reduce the possibility of accidents. The optical part of the device based on the Canon 450D DSLR camera is described. The tests have been performed to ensure the proper functioning of the device and to establish the image processing technique.

  10. Linearized inversion frameworks toward high-resolution seismic imaging

    KAUST Repository

    Aldawood, Ali

    2016-09-01

    internally multiply scattered seismic waves to obtain highly resolved images delineating vertical faults that are otherwise not easily imaged by primaries. Seismic interferometry is conventionally based on the cross-correlation and convolution of seismic traces to transform seismic data from one acquisition geometry to another. The conventional interferometric transformation yields virtual data that suffers from low temporal resolution, wavelet distortion, and correlation/convolution artifacts. I therefore incorporate a least-squares datuming technique to interferometrically transform vertical-seismic-profile surface-related multiples to surface-seismic-profile primaries. This yields redatumed data with high temporal resolution and less artifacts, which are subsequently imaged to obtain highly resolved subsurface images. Tests on synthetic examples demonstrate the efficiency of the proposed techniques, yielding highly resolved migrated sections compared with images obtained by imaging conventionally redatumed data. I further advance the recently developed cost-effective Generalized Interferometric Multiple Imaging procedure, which aims to not only image first but also higher-order multiples as well. I formulate this procedure as a linearized inversion framework and solve it as a least-squares problem. Tests of the least-squares Generalized Interferometric Multiple imaging framework on synthetic datasets and demonstrate that it could provide highly resolved migrated images and delineate vertical fault planes compared with the standard procedure. The results support the assertion that this linearized inversion framework can illuminate subsurface zones that are mainly illuminated by internally scattered energy.

  11. High resolution ultraviolet imaging spectrometer for latent image analysis.

    Science.gov (United States)

    Lyu, Hang; Liao, Ningfang; Li, Hongsong; Wu, Wenmin

    2016-03-21

    In this work, we present a close-range ultraviolet imaging spectrometer with high spatial resolution, and reasonably high spectral resolution. As the transmissive optical components cause chromatic aberration in the ultraviolet (UV) spectral range, an all-reflective imaging scheme is introduced to promote the image quality. The proposed instrument consists of an oscillating mirror, a Cassegrain objective, a Michelson structure, an Offner relay, and a UV enhanced CCD. The finished spectrometer has a spatial resolution of 29.30μm on the target plane; the spectral scope covers both near and middle UV band; and can obtain approximately 100 wavelength samples over the range of 240~370nm. The control computer coordinates all the components of the instrument and enables capturing a series of images, which can be reconstructed into an interferogram datacube. The datacube can be converted into a spectrum datacube, which contains spectral information of each pixel with many wavelength samples. A spectral calibration is carried out by using a high pressure mercury discharge lamp. A test run demonstrated that this interferometric configuration can obtain high resolution spectrum datacube. The pattern recognition algorithm is introduced to analyze the datacube and distinguish the latent traces from the base materials. This design is particularly good at identifying the latent traces in the application field of forensic imaging.

  12. Pulse retrieval algorithm for interferometric frequency-resolved optical gating based on differential evolution

    Science.gov (United States)

    Hyyti, Janne; Escoto, Esmerando; Steinmeyer, Günter

    2017-10-01

    A novel algorithm for the ultrashort laser pulse characterization method of interferometric frequency-resolved optical gating (iFROG) is presented. Based on a genetic method, namely, differential evolution, the algorithm can exploit all available information of an iFROG measurement to retrieve the complex electric field of a pulse. The retrieval is subjected to a series of numerical tests to prove the robustness of the algorithm against experimental artifacts and noise. These tests show that the integrated error-correction mechanisms of the iFROG method can be successfully used to remove the effect from timing errors and spectrally varying efficiency in the detection. Moreover, the accuracy and noise resilience of the new algorithm are shown to outperform retrieval based on the generalized projections algorithm, which is widely used as the standard method in FROG retrieval. The differential evolution algorithm is further validated with experimental data, measured with unamplified three-cycle pulses from a mode-locked Ti:sapphire laser. Additionally introducing group delay dispersion in the beam path, the retrieval results show excellent agreement with independent measurements with a commercial pulse measurement device based on spectral phase interferometry for direct electric-field retrieval. Further experimental tests with strongly attenuated pulses indicate resilience of differential-evolution-based retrieval against massive measurement noise.

  13. Influence of sample pool on interference pattern in defocused interferometric particle imaging.

    Science.gov (United States)

    Zhang, Hongxia; Zhou, Ye; Liu, Jing; Jia, Dagong; Liu, Tiegen

    2017-04-01

    Particles widely exist in various fields. In practical experiments, sometimes it is necessary to dissolve particles in water in a sample pool. This article proposes two typical layouts of the sample pool in defocused interferometric particle imaging (IPI). Layout I is the sample pool surface perpendicular to the incident light and layout II is the sample pool surface perpendicular to the scattered light. For layout I, the scattered light of the particles does not keep symmetric at the meridional and sagittal planes after being refracted by the sample pool surface, and elliptical interference patterns are formed at the defocused IPI image plane. But for layout II, the scattered light keeps symmetric after being refracted, and circular interference patterns are formed. Aimed at the two sample pool layouts, the ray-tracing software ZEMAX was used to simulate the spot shape of particles at different defocus distances. Furthermore, its effect on the ellipticity of the interference pattern with the tilt angle of the sample pool is analyzed. The relative error of the axis ratio for layout I does not exceed 9.2% at different defocus distances. The experimental results have good agreement with the theoretical analyses, and it indicates that layout II is more reasonable for the IPI system.

  14. Interferometric characterization of pyroelectrically activated micro-arrays of liquid lenses in lithium niobate crystals

    Science.gov (United States)

    Grilli, S.; Miccio, L.; Vespini, V.; Ferraro, P.

    2008-08-01

    In recent years a wide variety of liquid based optical elements have been conceived, designed and fabricated even for commercial products like digital cameras. The impressive development of microfluidic systems in conjunction with optics has led to the creation of a completely new field of investigation named optofludics. Among other things, the optofluidic area deals with the investigation and the realization of liquid micro-lenses. Different methods and configurations have been proposed in literature to achieve liquid variable micro-lenses. This paper reports about the possibility to achieve lensing effect by a relatively easy to accomplish technique based on an open microfluidic system consisting of a tiny amount of appropriate liquid manipulated by the pyroelectric effect onto a periodically poled LiNbO3 substrate. Basically, an electrowetting process is performed to actuate the liquid film by using the surface charges generated pyroelectrically under temperature variation. The configuration is electrode-less compared to standard electrowetting systems, thus improving the device flexibility and easiness of fabrication. The curvature of the liquid lenses has been characterized by interferometric techniques based on the evaluation of the phase map through digital holography. The results showing the evolution of the lens curvature with the temperature variation will be presented and discussed.

  15. Quantitative diffusion and swelling kinetic measurements using large-angle interferometric refractometry.

    Science.gov (United States)

    Saunders, John E; Chen, Hao; Brauer, Chris; Clayton, McGregor; Chen, Weijian; Barnes, Jack A; Loock, Hans-Peter

    2015-12-07

    The uptake and release of sorbates into films and coatings is typically accompanied by changes of the films' refractive index and thickness. We provide a comprehensive model to calculate the concentration of the sorbate from the average refractive index and the film thickness, and validate the model experimentally. The mass fraction of the analyte partitioned into a film is described quantitatively by the Lorentz-Lorenz equation and the Clausius-Mosotti equation. To validate the model, the uptake kinetics of water and other solvents into SU-8 films (d = 40-45 μm) were explored. Large-angle interferometric refractometry measurements can be used to characterize films that are between 15 μm to 150 μm thick and, Fourier analysis, is used to determine independently the thickness, the average refractive index and the refractive index at the film-substrate interface at one-second time intervals. From these values the mass fraction of water in SU-8 was calculated. The kinetics were best described by two independent uptake processes having different rates. Each process followed one-dimensional Fickian diffusion kinetics with diffusion coefficients for water into SU-8 photoresist film of 5.67 × 10(-9) cm(2) s(-1) and 61.2 × 10(-9) cm(2) s(-1).

  16. Scalable splitting algorithms for big-data interferometric imaging in the SKA era

    Science.gov (United States)

    Onose, Alexandru; Carrillo, Rafael E.; Repetti, Audrey; McEwen, Jason D.; Thiran, Jean-Philippe; Pesquet, Jean-Christophe; Wiaux, Yves

    2016-11-01

    In the context of next-generation radio telescopes, like the Square Kilometre Array (SKA), the efficient processing of large-scale data sets is extremely important. Convex optimization tasks under the compressive sensing framework have recently emerged and provide both enhanced image reconstruction quality and scalability to increasingly larger data sets. We focus herein mainly on scalability and propose two new convex optimization algorithmic structures able to solve the convex optimization tasks arising in radio-interferometric imaging. They rely on proximal splitting and forward-backward iterations and can be seen, by analogy, with the CLEAN major-minor cycle, as running sophisticated CLEAN-like iterations in parallel in multiple data, prior, and image spaces. Both methods support any convex regularization function, in particular, the well-studied ℓ1 priors promoting image sparsity in an adequate domain. Tailored for big-data, they employ parallel and distributed computations to achieve scalability, in terms of memory and computational requirements. One of them also exploits randomization, over data blocks at each iteration, offering further flexibility. We present simulation results showing the feasibility of the proposed methods as well as their advantages compared to state-of-the-art algorithmic solvers. Our MATLAB code is available online on GitHub.

  17. Modelling of mid-infrared interferometric signature of hot exozodiacal dust emission

    Science.gov (United States)

    Kirchschlager, Florian; Wolf, Sebastian; Brunngräber, Robert; Matter, Alexis; Krivov, Alexander V.; Labdon, Aaron

    2018-01-01

    Hot exozodiacal dust emission was detected in recent surveys around two dozen main-sequence stars at distances of less than 1 au using the H- and K-band interferometry. Due to the high contrast as well as the small angular distance between the circumstellar dust and the star, direct observation of this dust component is challenging. An alternative way to explore the hot exozodiacal dust is provided by mid-infrared interferometry. We analyse the L, M and N bands interferometric signature of this emission in order to find stronger constraints for the properties and the origin of the hot exozodiacal dust. Considering the parameters of nine debris disc systems derived previously, we model the discs in each of these bands. We find that the M band possesses the best conditions to detect hot dust emission, closely followed by L and N bands. The hot dust in three systems - HD 22484 (10 Tau), HD 102647 (β Leo) and HD 177724 (ζ Aql) - shows a strong signal in the visibility functions, which may even allow one to constrain the dust location. In particular, observations in the mid-infrared could help to determine whether the dust piles up at the sublimation radius or is located at radii up to 1 au. In addition, we explore observations of the hot exozodiacal dust with the upcoming mid-infrared interferometer Multi AperTure mid-Infrared SpectroScopic Experiment (MATISSE) at the Very Large Telescope Interferometer.

  18. Simultaneous refractive index and thickness measurement with the transmission interferometric adsorption sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sannomiya, Takumi; Voeroes, Janos [Laboratory of Biosensors and Bioelectronics, Department of Information Technology and Electrical Engineering, ETH Zurich, 8092, Zurich (Switzerland); Balmer, Tobias E [Materials Research Center, ETH Zurich, 8093, Zurich (Switzerland); Heuberger, Manfred, E-mail: sannomiya@biomed.ee.ethz.c, E-mail: tobias.balmer@mat.ethz.c, E-mail: manfred.heuberger@empa.c, E-mail: janos.voros@biomed.ee.ethz.c [Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, 8093, Zurich (Switzerland)

    2010-10-13

    Refractive index and thickness of the adlayer are determined simultaneously using the transmission interferometric adsorption sensor (TInAS). Optical biosensors, where both refractive index and thickness of a homogeneous adlayer (thus the adsorbed mass) are determined simultaneously, so-called model-free biosensors, are important tools to investigate the adsorbed mass of biomolecules with unknown conformation. Our proposed calculation method enables model-free biosensing from a single spectrum acquired by a simple TInAS setup, namely using information of peak/dip positions as well as peak/dip intensities. The feasibility of this method was experimentally tested by adsorbing polyelectrolyte multilayer as well as biomolecules. To validate the new method also for the more intricate heterogeneous adlayer, the apparent refractive index and thickness were assessed theoretically by simulating a selection of different adsorbate configurations with the multiple multipole program (MMP). We found that a lateral inhomogeneity of the adsorbate (e.g. islands or adsorbed colloids) results in correct thickness and in reduced refractive index averaged in proportion to their density while vertically inhomogeneous density caused more complex responses. However, the apparent mass was always correct. Measurement errors can lead to significant errors in the apparent refractive index, particularly when the adlayer is very thin (<5 nm). This model-free TInAS technique would be useful not only for the measurement of adsorbed mass but also for the conformational analysis of the adsorbed molecules.

  19. Extrinsic Fabry-Perot interferometric sensor using a polarization-switched phase interrogator

    Science.gov (United States)

    Xia, Ji; Wang, Fuyin; Yang, Yangyang; Xiong, Shuidong; Luo, Hong; Wei, Wenjian

    2016-10-01

    In this paper, a phase variation tracking method for the extrinsic Fabry-Perot interferometric (EFPI) voice sensing system is designed and experimentally demonstrated through a polarization-switched unit based on the combination of polarization-maintaining fiber Bragg grating (PMFBG). The measurements at two operation wavelengths are firstly achieved in one total-optical path, which eliminates the imbalance of optical power from the external disturbances, optical source fluctuation, different detecting response of photoelectric detector and different background noise. Two operation wavelengths reflected from a PMFBG for interference phase tracking are switched via an electro-optic modulator at a high switching speed of 10 kHz. Besides, an ellipse fitting-differential cross multiplication (EF-DCM) algorithm is proposed and illustrated for interrogating the variation of EFPI cavity gap length of the EFPI voice sensor effectively. Preliminary experimental results have proven that the polarization-switched system based on the EF-DCM algorithm could find potential applications in the fields of marine acoustic, medical science measurements, etc.

  20. Remote access to an interferometric fringes stabilization active system via RENATA

    Science.gov (United States)

    Espitia-Gómez, Javier; Ángel-Toro, Luciano

    2013-11-01

    The Advanced Technology National Network (RENATA, for its acronym in Spanish) is a Colombian, collaborative work tool, linked to other networks worldwide, in which take participation researchers, teachers and students, by sharing laboratory resources located in different universities, institutes and research centers throughout the country. In the Universidad EAFIT (Medellín, Colombia) it has been designed an interferometric fringes stabilization active system, which can be accessed remotely via the RENATA network. A Mach-Zehnder interferometer was implemented, with independent piezoelectric actuators in each arm, with which the lengths of optical path of light that goes over in each of them can be modified. Using these actuators, one can simultaneously perturb the system and compensate the phase differences caused by that perturbation. This allows us to experiment with different disturbs, and analyze the system response to each one of them. This can be made from any location worldwide, and especially from those regions in which optical and optoelectronic components required for the implementation of the interferometer or for the stabilization system are not available. The device can also be used as a platform in order to conduct diverse experiments, involving optical and controlling aspects, constituting with this in a pedagogic tool. For the future, it can be predicted that remote access to available applications would be possible, as well as modifications of the implemented code in labVIEW™, so that researchers and teachers can adapt and improve their functionalities or develop new applications, based on the collaborative work.

  1. Interferometric method for quantitatively testing the RadOptic effect in bulk semiconductors

    Science.gov (United States)

    Peng, Bo-dong; Song, Yan; Hei, Dong-wei; Zhao, Jun

    2017-10-01

    For the quantitative investigation of MeV-photon-induced changes in the refractive indices of bulk semiconductors, a model was established to describe the evolution of the excess carrier density, including the generation and recombination processes. The two key parameters of the evolution model, namely, the summed injection intensity and the gamma intensity curve, were obtained via dose measurements and gamma pulse monitoring, respectively. An interferometric method of measuring instantaneous changes in the refractive index and obtaining real-time measurements of the excess carrier density in bulk materials was successfully implemented. The probe beam was transmitted through a single-mode fiber to form double-beam interference in a slab geometry. Two bulk samples, one consisting of intrinsic GaAs and one of intrinsic ZnO, were tested. The recombination time constant of the intrinsic GaAs sample was found to be approximately 0.6 ns and did not vary distinctly with the photon energy, whereas the ZnO sample's recombination behavior consisted of two components. The short component was evident when short and intense pulses were incident, whereas the long component dominated under long and relatively weak pulses. The method reported in this work can be used to study the excess carrier dynamics induced by pulsed gamma radiation and to investigate the mechanisms of refractive index modulation under pulsed gamma conditions; thus, it is expected to be beneficial for guiding the development of RadOptic systems based on bulk materials.

  2. New interferometric technique to measure the length (thickness) of opaque objects using a commercial interferometer

    Science.gov (United States)

    Suratkar, Amit R.; Davies, Angela D.; Farahi, Faramarz

    2007-09-01

    Wavelength scanning interferometry offers many advantages over traditional phase shifting interferometry, most significantly the elimination of mechanical movement of the part/s for phase modulation by implementing a tunable light source. Further, Fourier analysis on the interference time history enables this technique to accurately measure distances, treating the distance between two optical surfaces as an interferometric cavity. We propose to use a newly acquired wavelength scanning Fizeau interferometer from Zygo Corporation, the MST (Multiple Surface Transform) to explore the limits of absolute thickness metrology to measure an opaque cavity, such as a gauge block. While transparent cavities can be measured with ease in a Fizeau setup, opaque cavities need additional optics. A two mirror Sagnac configuration in conjunction with the interferometer from Zygo Corporation is used to measure the length (thickness) of a 1 inch gauge block. Current gauge block measurements rely on comparison methods to determine the fractional length with respect to a reference or master gauge block or use techniques which require the absolute length of the gauge block to be previously known. By using wavelength scanning interferometry, the absolute length of the gauge block can be determined directly within limits of the repeatability of the instrument. While other techniques implement a point by point approach for measurement or use interpolation methods, we simply use a large aperture to provide the thickness variation over the sample. Experimental results of a 1 inch gauge block along with an uncertainty estimate are discussed.

  3. The circumstellar environment of the B[e] star GG Car: an interferometric modeling

    Science.gov (United States)

    Domiciano de Souza, A.; Borges Fernandes, M.; Carciofi, A. C.; Chesneau, O.

    2015-01-01

    The research of stars with the B[e] phenomenon is still in its infancy, with several unanswered questions. Physically realistic models that treat the formation and evolution of their complex circumstellar environments are rare. The code HDUST (developed by A. C. Carciofi and J. Bjorkman) is one of the few existing codes that provides a self-consistent treatment of the radiative transfer in a gaseous and dusty circumstellar environment seen around B[e] supergiant stars. In this work we used the HDUST code to study the circumstellar medium of the binary system GG Car, where the primary component is probably an evolved B[e] supergiant. This system also presents a disk (probably circumbinary), which is responsible for the molecular and dusty signatures seen in GG Car spectra. We obtained VLTI/MIDI data on GG~Car at eight baselines, which allowed to spatially resolve the gaseous and dusty circumstellar environment. From the interferometric visibilities and SED modeling with HDUST, we confirm the presence of a compact ring, where the hot dust lies. We also show that large grains can reproduce the lack of structure in the SED and visibilities across the silicate band. We conclude the dust condensation site is much closer to the star than previously thought. This result provides stringent constraints on future theories of grain formation and growth around hot stars.

  4. The w-effect in interferometric imaging: from a fast sparse measurement operator to superresolution

    Science.gov (United States)

    Dabbech, A.; Wolz, L.; Pratley, L.; McEwen, J. D.; Wiaux, Y.

    2017-11-01

    Modern radio telescopes, such as the Square Kilometre Array, will probe the radio sky over large fields of view, which results in large w-modulations of the sky image. This effect complicates the relationship between the measured visibilities and the image under scrutiny. In algorithmic terms, it gives rise to massive memory and computational time requirements. Yet, it can be a blessing in terms of reconstruction quality of the sky image. In recent years, several works have shown that large w-modulations promote the spread spectrum effect. Within the compressive sensing framework, this effect increases the incoherence between the sensing basis and the sparsity basis of the signal to be recovered, leading to better estimation of the sky image. In this article, we revisit the w-projection approach using convex optimization in realistic settings, where the measurement operator couples the w-terms in Fourier and the de-gridding kernels. We provide sparse, thus fast, models of the Fourier part of the measurement operator through adaptive sparsification procedures. Consequently, memory requirements and computational cost are significantly alleviated at the expense of introducing errors on the radio interferometric data model. We present a first investigation of the impact of the sparse variants of the measurement operator on the image reconstruction quality. We finally analyse the interesting superresolution potential associated with the spread spectrum effect of the w-modulation, and showcase it through simulations. Our c++ code is available online on GitHub.

  5. Air temperature measurements based on the speed of sound to compensate long distance interferometric measurements

    Directory of Open Access Journals (Sweden)

    Astrua Milena

    2014-01-01

    Full Text Available A method to measure the real time temperature distribution along an interferometer path based on the propagation of acoustic waves is presented. It exploits the high sensitivity of the speed of sound in air to the air temperature. In particular, it takes advantage of a special set-up where the generation of the acoustic waves is synchronous with the amplitude modulation of a laser source. A photodetector converts the laser light to an electronic signal considered as reference, while the incoming acoustic waves are focused on a microphone and generate a second signal. In this condition, the phase difference between the two signals substantially depends on the temperature of the air volume interposed between the sources and the receivers. The comparison with the traditional temperature sensors highlighted the limit of the latter in case of fast temperature variations and the advantage of a measurement integrated along the optical path instead of a sampling measurement. The capability of the acoustic method to compensate the interferometric distance measurements due to air temperature variations has been demonstrated for distances up to 27 m.

  6. Heterogeneous radio-over-fiber passive access network architecture to mitigate Rayleigh backscattering interferometric beat noise.

    Science.gov (United States)

    Yeh, C H; Chow, C W

    2011-03-28

    We propose and experimentally demonstrate a hybrid radio-over-fiber (ROF) wavelength division multiplexed and time division multiplexed passive optical network (WDM-TDM PON) architecture to mitigate Rayleigh backscattering (RB) interferometric beat noises. Here, only a single wavelength is needed at the central office (CO) to generate the downstream baseband data for optical wired application and optical millimeter-wave (mm-wave) signal for wireless application. The upstream signal is produced by remodulating the downstream signal. No optical filter is required at the optical network unit/remote antenna unit (ONU/RAU) to separate the optical wired and optical mm-wave signals. In the proposed network, 10 Gb/s differential phase shift keying (DPSK) signal is used for the downstream optical wired application and 2.5 Gb/s on-off keying (OOK) signal on 20 GHz carrier is used for the optical mm-wave signal. In each ONU, a reflective optical semiconductor amplifier (RSOA) is used to remodulate and produce a 2.5 Gb/s OOK format for upstream traffic. As the back-refection produced by the downstream DPSK signal and the upstream OOK signal is traveling in different fiber path, RB noise at the CO can be completely mitigated.

  7. Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    1997-01-01

    Full Text Available Interferometric techniques allow the SuperDARN coherent HF radars to determine the elevation angles of returned backscatter, giving information on the altitude of the scatter volume, in the case of ionospheric backscatter, or the reflection altitude, in the case of ground backscatter. Assumptions have to be made in the determination of elevation angles, including the direction of arrival, or azimuth, of the returned signals, usually taken to be the forward look-direction (north of the radars, specified by the phasing of the antenna arrays. It is shown that this assumption is not always valid in the case of ground backscatter, and that significant returns can be detected from the backward look-direction of the radars. The response of the interferometer to backscatter from behind the radar is modelled and compared with observations. It is found that ground backscatter from a field-of-view that is the mirror image of the forward-looking field-of-view is a common feature of the observations, and this interpretation successfully explains several anomalies in the received backscatter.

  8. Interferometric evidence for the observation of ground backscatter originating behind the CUTLASS coherent HF radars

    Directory of Open Access Journals (Sweden)

    S. E. Milan

    Full Text Available Interferometric techniques allow the SuperDARN coherent HF radars to determine the elevation angles of returned backscatter, giving information on the altitude of the scatter volume, in the case of ionospheric backscatter, or the reflection altitude, in the case of ground backscatter. Assumptions have to be made in the determination of elevation angles, including the direction of arrival, or azimuth, of the returned signals, usually taken to be the forward look-direction (north of the radars, specified by the phasing of the antenna arrays. It is shown that this assumption is not always valid in the case of ground backscatter, and that significant returns can be detected from the backward look-direction of the radars. The response of the interferometer to backscatter from behind the radar is modelled and compared with observations. It is found that ground backscatter from a field-of-view that is the mirror image of the forward-looking field-of-view is a common feature of the observations, and this interpretation successfully explains several anomalies in the received backscatter.

  9. First step towards an interferometric and localized surface plasmon fiber optic sensor

    Science.gov (United States)

    Muri, Harald Ian D. I.; Bano, Andon; Hjelme, Dag Roar

    2017-04-01

    We present a first demonstration of a novel multi-parameter fiber optic (FO) sensor concept based on gold nanoparticles (GNP) embedded in a stimuli-responsive hydrogel material. A hemispherical hydrogel immobilized on the optical fiber end-face forms a low-finesse Fabry-Perot (FP) interferometer. The GNPs exhibit local surface plasmon resonance (LSPR) that is sensitive towards the refractive index of the surrounding environment, while the stimuli-responsive hydrogel is sensitive towards specific chemical compounds. We evaluate the quality of the interferometric and LSPR signal as a function GNP concentration and of hydrogel swelling degree stimulated by ethanol solutions. The GNPs shows to have little influence on the visibility of the FP etalon, while LSPR of GNP shows to be sensitive towards the surface refractive index rather than bulk refractive index. This demonstration shows that the sensor concept has the potential to be used in applications such as an intravenous two-parametric real-time sensor for medical purpose.

  10. Remotely Sensed Active Layer Thickness (ReSALT at Barrow, Alaska Using Interferometric Synthetic Aperture Radar

    Directory of Open Access Journals (Sweden)

    Kevin Schaefer

    2015-03-01

    Full Text Available Active layer thickness (ALT is a critical parameter for monitoring the status of permafrost that is typically measured at specific locations using probing, in situ temperature sensors, or other ground-based observations. Here we evaluated the Remotely Sensed Active Layer Thickness (ReSALT product that uses the Interferometric Synthetic Aperture Radar technique to measure seasonal surface subsidence and infer ALT around Barrow, Alaska. We compared ReSALT with ground-based ALT obtained using probing and calibrated, 500 MHz Ground Penetrating Radar at multiple sites around Barrow. ReSALT accurately reproduced observed ALT within uncertainty of the GPR and probing data in ~76% of the study area. However, ReSALT was less than observed ALT in ~22% of the study area with well-drained soils and in ~1% of the area where soils contained gravel. ReSALT was greater than observed ALT in some drained thermokarst lake basins representing ~1% of the area. These results indicate remote sensing techniques based on InSAR could be an effective way to measure and monitor ALT over large areas on the Arctic coastal plain.

  11. Optical microscope using an interferometric source of two-color, two-beam entangled photons

    Science.gov (United States)

    Dress, William B.; Kisner, Roger A.; Richards, Roger K.

    2004-07-13

    Systems and methods are described for an optical microscope using an interferometric source of multi-color, multi-beam entangled photons. A method includes: downconverting a beam of coherent energy to provide a beam of multi-color entangled photons; converging two spatially resolved portions of the beam of multi-color entangled photons into a converged multi-color entangled photon beam; transforming at least a portion of the converged multi-color entangled photon beam by interaction with a sample to generate an entangled photon specimen beam; and combining the entangled photon specimen beam with an entangled photon reference beam within a single beamsplitter. An apparatus includes: a multi-refringent device providing a beam of multi-color entangled photons; a condenser device optically coupled to the multi-refringent device, the condenser device converging two spatially resolved portions of the beam of multi-color entangled photons into a converged multi-color entangled photon beam; a beam probe director and specimen assembly optically coupled to the condenser device; and a beam splitter optically coupled to the beam probe director and specimen assembly, the beam splitter combining an entangled photon specimen beam from the beam probe director and specimen assembly with an entangled photon reference beam.

  12. Interferometric characterization of few-mode fibers (FMF) for mode-division multiplexing (MDM)

    Science.gov (United States)

    Muliar, O.; Usuga, M. A.; Rottwitt, K.; Lægsgaard, J.

    2015-03-01

    The rapid growth of global data traffic demands the continuous search for new technologies and systems that could increase transmission capacity in optical links and recent experiments show that to do so, it is advantageous to explore new degrees of freedom such as polarization, wavelength or optical modes. Mode division multiplexing (MDM) appears in this context as a promising and viable solution for such capacity increase, since it utilizes multiple spatial modes of an optical fiber as individual communication channels for data transmission. In order to evaluate its performance, a MDM system requires advanced characterization methods with regard to the modal content of its photonics components and in particular of the fibers involved for data transmission. In this contribution we present a time-domain interferometric technique for a full modal characterization of few mode fibers (FMF), commonly used in a MDM scenario. This experimental technique requires the use of a Mach-Zehnder interferometer, where the reference's path length is controlled by an optical delay line. The interference between the output beams of reference and fiber under test (FUT) is recorded on a CCD camera and a careful evaluation of the resulting interferograms allows us to have full access to key parameters such as number of modes, modal weight, differential time delay between propagating modes and intensity profiles. In this work, we apply this simple and complete characterization method to the case of a short link with two optical modes propagating in a FMF, which illustrates its potential as a diagnostic tool for MDM systems.

  13. Interferometric Monitoring of Gamma-Ray Bright AGNs: S5 0716+714

    Science.gov (United States)

    Lee, Jee Won; Lee, Sang-Sung; Hodgson, Jeffrey A.; Kim, Dae-Won; Algaba, Juan-Carlos; Kang, Sincheol; Kang, Jiman; Kim, Sungsoo S.

    2017-06-01

    We present the results of very long baseline interferometry (VLBI) observations of gamma-ray bright blazar S5 0716+714 using the Korean VLBI Network (KVN) at the 22, 43, 86, and 129 GHz bands, as part of the Interferometric Monitoring of Gamma-ray Bright active galactic nuclei (iMOGABA) KVN key science program. Observations were conducted in 29 sessions from 2013 January 16 to 2016 March 1, with the source being detected and imaged at all available frequencies. In all epochs, the source was compact on the milliarcsecond scale, yielding a compact VLBI core dominating the synchrotron emission on these scales. Based on the multiwavelength data between 15 GHz (Owens Valley Radio Observatory) and 230 GHz (Submillimeter Array), we found that the source shows multiple prominent enhancements of the flux density at the centimeter (cm) and millimeter (mm) wavelengths, with mm enhancements leading cm enhancements by -16 ± 8 days. The turnover frequency was found to vary between 21 and 69 GHz during our observations. By assuming a synchrotron self-absorption model for the relativistic jet emission in S5 0716+714, we found the magnetic field strength in the mas emission region to be ≤5 mG during the observing period, yielding a weighted mean of 1.0 ± 0.6 mG for higher turnover frequencies (e.g., >45 GHz).

  14. An interferometric radar for displacement measurement and its application in civil engineering structures

    Science.gov (United States)

    Su, D.; Nagayama, T.; Sun, Z.; Fujino, Y.

    2012-04-01

    Recent progress in radar techniques and systems has led to the development of a microwave interferometer, potentially suitable for non-contact displacement monitoring of civil engineering structures. This paper describes a new interferometric radar system, named IBIS-S, which is possible to measure the static or dynamic displacement at multiple points of structures simultaneously with high accuracy. In this paper, the technical characteristics and specification of the radar system is described. Subsequently, the actual displacement sensitivity of the equipment is illustrated using the laboratory tests with random motion upon a shake table. Finally the applications of the radar system to the measurement on a cable-stayed bridge and a prestressed concrete bridge are presented and discussed. Results show that the new system is an accurate and effective method to measure displacements of multiple targets of structures. It should be noted that the current system can only measure the vibration of the target position along the sensor's line of sight. Hence, proper caution should be taken when designing the sensor posture and prior knowledge of the direction of motion is necessary.

  15. Interferometric windows characterization up to 450 K for shock wave experiments: Hugoniot curves and refractive index

    Directory of Open Access Journals (Sweden)

    Godefroit J.-L.

    2012-08-01

    Full Text Available Conventional shock wave experiments need interferometric windows in order to determine the equation of state of a large variety of metals. Lithium fluoride (LiF and sapphire are extensively used for that purpose because their optical transparencies enable the optical diagnostics at interfaces under a given range of shock pressure. In order to simulate and analyse the experiments it is necessary to gather a correct knowledge of the optical and mechanical properties of these windows. Therefore, our window supplies are systematically characterized and an experimental campaign under shock loading is conducted. Our preliminary work on LiF windows at 532 nm is in good agreement with literature data at room temperature and the new characterization at 450 K enables a better interpretation of our preheated target experiments. It confirms the predominant effect of density on optical properties under pressure and temperature. The present work demonstrates that the initial density determination is a key point and that the uncertainties need to be improved. For that purpose, complementary experiments are conducted on LiF windows with simplified target designs and enriched diagnostics, coupling VISAR (532 nm and PdV (1550 nm diagnostics. Furthermore, a similar campaign is conducted on sapphire windows with symmetric impact configuration.

  16. Two-dimensional interferometric characterization of laser-induced refractive index profiles in bulk Topas polymer

    Science.gov (United States)

    Hessler, Steffen; Rosenberger, Manuel; Schmauss, Bernhard; Hellmann, Ralf

    2018-01-01

    In this paper we precisely determine laser-induced refractive index profiles created in cyclic olefin copolymer Topas 6017 employing a sophisticated phase shifting Mach-Zehnder interferometry approach. Beyond the usual one-dimensional modification depth measurement we highlight that for straight waveguide structures also a two-dimensional refractive index distribution can be directly obtained providing full information of a waveguide's exact cross section and its gradient refractive index contrast. Deployed as direct data input in optical waveguide simulation, the evaluated 2D refractive index profiles permit a detailed calculation of the waveguides' actual mode profiles. Furthermore, conventional one-dimensional interferometric measurements for refractive index depth profiles with varying total imposed laser fluence of a 248 nm KrF excimer laser are included to investigate the effect on refractive index modification depth. Maximum surface refractive index increase turns out to attain up to 1.86 ·10-3 enabling laser-written optical waveguide channels. Additionally, a comprehensive optical material characterization in terms of dispersion, thermo-optic coefficient and absorption measurement of unmodified and UV-modified Topas 6017 is carried out.

  17. An acoustic thermometer for air refractive index estimation in long distance interferometric measurements

    Science.gov (United States)

    Pisani, Marco; Astrua, Milena; Zucco, Massimo

    2018-02-01

    We present a method to measure the temperature along the path of an optical interferometer based on the propagation of acoustic waves. It exploits the high sensitivity of the speed of sound to air temperature. In particular, it takes advantage of a technique where the generation of acoustic waves is synchronous with the amplitude modulation of a laser source. A photodetector converts the laser light into an electronic signal used as a reference, while the incoming acoustic waves are focused on a microphone and generate the measuring signal. Under this condition, the phase difference between the two signals substantially depends on the temperature of the air volume interposed between the sources and the receivers. A comparison with traditional temperature sensors highlighted the limit of the latter in the case of fast temperature variations and the advantage of a measurement integrated along the optical path instead of a sampling measurement. The capability of the acoustic method to compensate for the interferometric distance measurements due to air temperature variations has been demonstrated to the level of 0.1 °C corresponding to 10‑7 on the refractive index of air. We applied the method indoor for distances up to 27 m, outdoor at 78 m and finally tested the acoustic thermometer over a distance of 182 m.

  18. Laser holographic interferometric measurements of the flow behind a rearward facing step

    Science.gov (United States)

    Leonard, Rachel; Chokani, Ndaona

    1993-01-01

    A holographic interferometer has been designed, constructed, and evaluated in an experimental study of the supersonic flow over a rearward facing step. The nominal Mach number at the corner was 2.05 +/- 0.04 and the Reynolds number per inch was 11.9 x 10 exp 6. The holographic interferometric measurements were supplemented by classical measurements of surface pressure, oil flow, and schlieren visualization. The effects of step height and step width were examined. A method to determine the reattachment point from the interferograms was examined and found to be in good agreement with the other measurement techniques. The reattachment point moved closer to the step as the step height was decreased, but its location did not change with varying step width. In addition to providing surface data for the flow over a rearward facing step, this study provides quantitative off-surface density data and Mach number data throughout the flow, obtained from the holographic interferometry measurements, which are suited for code validation.

  19. Modeling and Validation of Performance Limitations for the Optimal Design of Interferometric and Intensity-Modulated Fiber Optic Displacement Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Moro, Erik A. [Los Alamos National Laboratory

    2012-06-07

    Optical fiber sensors offer advantages over traditional electromechanical sensors, making them particularly well-suited for certain measurement applications. Generally speaking, optical fiber sensors respond to a desired measurand through modulation of an optical signal's intensity, phase, or wavelength. Practically, non-contacting fiber optic displacement sensors are limited to intensity-modulated and interferometric (or phase-modulated) methodologies. Intensity-modulated fiber optic displacement sensors relate target displacement to a power measurement. The simplest intensity-modulated sensor architectures are not robust to environmental and hardware fluctuations, since such variability may cause changes in the measured power level that falsely indicate target displacement. Differential intensity-modulated sensors have been implemented, offering robustness to such intensity fluctuations, and the speed of these sensors is limited only by the combined speed of the photodetection hardware and the data acquisition system (kHz-MHz). The primary disadvantages of intensity-modulated sensing are the relatively low accuracy (?m-mm for low-power sensors) and the lack of robustness, which consequently must be designed, often with great difficulty, into the sensor's architecture. White light interferometric displacement sensors, on the other hand, offer increased accuracy and robustness. Unlike their monochromatic-interferometer counterparts, white light interferometric sensors offer absolute, unambiguous displacement measurements over large displacement ranges (cm for low-power, 5 mW, sources), necessitating no initial calibration, and requiring no environmental or feedback control. The primary disadvantage of white light interferometric displacement sensors is that their utility in dynamic testing scenarios is limited, both by hardware bandwidth and by their inherent high-sensitivity to Doppler-effects. The decision of whether to use either an intensity

  20. Advances in Measuring Soil Moisture using Global Navigation Satellite Systems Interferometric Reflectometry (GNSS-IR)

    Science.gov (United States)

    Moore, A. W.; Small, E. E.; Owen, S. E.; Hardman, S. H.; Wong, C.; Freeborn, D. J.; Larson, K. M.

    2016-12-01

    GNSS Interferometric Reflectometry (GNSS-IR) uses GNSS signals reflected off the land to infer changes in the near-antenna environment and monitor fluctuations in soil moisture, as well as other related hydrologic variables: snow depth/snow water equivalent (SWE), vegetation water content, and water level [Larson and Small, 2013; McCreight, et al., 2014; Larson et al., 2013]. GNSS instruments installed by geoscientists and surveyors to measure land motions can measure soil moisture fluctuations with accuracy (RMSE sites in the western U.S. (Figure 1) from a single network (the Plate Boundary Observatory) has been operated by the University of Colorado (CU) at http://xenon.colorado.edu/portal since October 2012. JPL and CU are funded by NASA ESTO to refactor the PBO H2O software within an Apache OODT framework for robust operational analysis of soil moisture data and auto-configuration when new stations are added. We will report progress on the new GNSS H2O analysis portal, and plans to expand to global networks and from GPS to other GNSS signals. ReferencesLarson, K. M., & Small, E. E. (2013) Eos, 94(52), 505-512. McCreight, J. L., Small, E. E., & Larson, K. M. (2014). Water Resour. Res., 50(8), 6892-6909. Larson, K. M., Ray, R. D., Nievinski, F. G., & Freymueller, J. T. (2013). IEEE Geosci Remote S, 10(5), 1200-1204. Small, E. E., Larson, K. M., Chew, C. C., Dong, J., & Ochsner, T. E. (2016). IEEE J Sel. Top. Appl. PP(39). Figure 1: (R) Western U.S. GPS-IR soil moisture sites. (L): Products derived from GNSS reflection data for (clockwise from upper left) vegetation water content, SWE, sea level, and volumetric soil moisture.

  1. Monitoring forest carbon in a Tanzanian woodland using interferometric SAR: a novel methodology for REDD.

    Science.gov (United States)

    Solberg, Svein; Gizachew, Belachew; Næsset, Erik; Gobakken, Terje; Bollandsås, Ole Martin; Mauya, Ernest William; Olsson, Håkan; Malimbwi, Rogers; Zahabu, Eliakimu

    2015-12-01

    REDD+ implementation requires establishment of a system for measuring, reporting and verification (MRV) of forest carbon changes. A challenge for MRV is the lack of satellite based methods that can track not only deforestation, but also degradation and forest growth, as well as a lack of historical data that can serve as a basis for a reference emission level. Working in a miombo woodland in Tanzania, we here aim at demonstrating a novel 3D satellite approach based on interferometric processing of radar imagery (InSAR). Forest carbon changes are derived from changes in the forest canopy height obtained from InSAR, i.e. decreases represent carbon loss from logging and increases represent carbon sequestration through forest growth. We fitted a model of above-ground biomass (AGB) against InSAR height, and used this to convert height changes to biomass and carbon changes. The relationship between AGB and InSAR height was weak, as the individual plots were widely scattered around the model fit. However, we consider the approach to be unique and feasible for large-scale MRV efforts in REDD+ because the low accuracy was attributable partly to small plots and other limitations in the data set, and partly to a random pixel-to-pixel variation in trunk forms. Further processing of the InSAR data provides data on the categories of forest change. The combination of InSAR data from the Shuttle RADAR Topography Mission (SRTM) and the TanDEM-X satellite mission provided both historic baseline of change for the period 2000-2011, as well as annual change 2011-2012. A 3D data set from InSAR is a promising tool for MRV in REDD+. The temporal changes seen by InSAR data corresponded well with, but largely supplemented, the changes derived from Landsat data.

  2. Interferometric observations of the supergiant stars α Orionis and α Herculis with FLUOR at IOTA

    Science.gov (United States)

    Perrin, G.; Ridgway, S. T.; Coudé du Foresto, V.; Mennesson, B.; Traub, W. A.; Lacasse, M. G.

    2004-05-01

    We report the observations in the K band of the red supergiant star α Orionis and of the bright giant star α Herculis with the FLUOR beamcombiner at the IOTA interferometer. The high quality of the data allows us to estimate limb-darkening and derive precise diameters in the K band which combined with bolometric fluxes yield effective temperatures. In the case of Betelgeuse, data collected at high spatial frequency although sparse are compatible with circular symmetry and there is no clear evidence for departure from circular symmetry. We have combined the K band data with interferometric measurements in the L band and at 11.15 μm. The full set of data can be explained if a 2055 K layer with optical depths τK=0.060±0.003, τL=0.026±0.002 and τ11.15 μm= 2.33±0.23 is added 0.33 R* above the photosphere providing a first consistent view of the star in this range of wavelengths. This layer provides a consistent explanation for at least three otherwise puzzling observations: the wavelength variation of apparent diameter, the dramatic difference in limb darkening between the two supergiant stars, and the previously noted reduced effective temperature of supergiants with respect to giants of the same spectral type. Each of these may be simply understood as an artifact due to not accounting for the presence of the upper layer in the data analysis. This consistent picture can be considered strong support for the presence of a sphere of warm water vapor, proposed by \\cite{tsuji2000} when interpreting the spectra of strong molecular lines. Based on observations collected at the IOTA interferometer, Whipple Observatory, Mount Hopkins, Arizona.

  3. Tunable coherent radiation at soft X-ray wavelengths: Generation and interferometric applications

    Energy Technology Data Exchange (ETDEWEB)

    Rosfjord, Kristine Marie [Univ. of California, Berkeley, CA (United States)

    2004-01-01

    The availability of high power, spectrally and spatially coherent soft x-rays (SXR) would facilitate a wide variety of experiments as this energy region covers the primary resonances of many magnetic and biological materials. Specifically, there are the carbon and oxygen K-edges that are critical for biological imaging in the water window and the L-edges of iron, nickel, and cobalt for which imaging and scattering studies can be performed. A new coherent soft X-ray branchline at the Advanced Light Source has begun operation (beamline 12.0.2). Using the third harmonic from an 8 cm period undulator, this branch delivers coherent soft x-rays with photon energies ranging from 200eV to 1keV. This branchline is composed of two sub-branches one at 14X demagnification and the other 8X demagnification. The former is optimized for use at 500eV and the latter at 800eV. Here the expected power from the third harmonic of this undulator and the beamline design and characterization is presented. The characterization includes measurements on available photon flux as well as a series of double pinhole experiments to determine the coherence factor with respect to transverse distance. The first high quality Airy patterns at SXR wavelengths are created with this new beamline. The operation of this new beamline allows for interferometry to be performed in the SXR region. Here an interferometric experiment designed to directly determine the index of refraction of a material under test is performed. Measurements are first made in the EUV region using an established beamline (beamline12.0.1) to measure silicon, ruthenium and tantalum silicon nitride. This work is then extended to the SXR region using beamline 12.0.2 to test chromium and vanadium.

  4. Low-Coherence Interferometric Fiber-Optic Sensors with Potential Applications as Biosensors.

    Science.gov (United States)

    Hirsch, Marzena; Majchrowicz, Daria; Wierzba, Paweł; Weber, Matthieu; Bechelany, Mikhael; Jędrzejewska-Szczerska, Małgorzata

    2017-01-28

    Fiber-optic Fabry-Pérot interferometers (FPI) can be applied as optical sensors, and excellent measurement sensitivity can be obtained by fine-tuning the interferometer design. In this work, we evaluate the ability of selected dielectric thin films to optimize the reflectivity of the Fabry-Pérot cavity. The spectral reflectance and transmittance of dielectric films made of titanium dioxide (TiO₂) and aluminum oxide (Al₂O₃) with thicknesses from 30 to 220 nm have been evaluated numerically and compared. TiO₂ films were found to be the most promising candidates for the tuning of FPI reflectivity. In order to verify and illustrate the results of modelling, TiO₂ films with the thickness of 80 nm have been deposited on the tip of a single-mode optical fiber by atomic layer deposition (ALD). The thickness, the structure, and the chemical properties of the films have been determined. The ability of the selected TiO₂ films to modify the reflectivity of the Fabry-Pérot cavity, to provide protection of the fibers from aggressive environments, and to create multi-cavity interferometric sensors in FPI has then been studied. The presented sensor exhibits an ability to measure refractive index in the range close to that of silica glass fiber, where sensors without reflective films do not work, as was demonstrated by the measurement of the refractive index of benzene. This opens up the prospects of applying the investigated sensor in biosensing, which we confirmed by measuring the refractive index of hemoglobin and glucose.

  5. Recent progress in bidirectional interrogation techniques for enhancing multiplexing capability of fiber optic white light interferometric sensors

    Science.gov (United States)

    Yuan, Libo; Zhou, Limin; Jin, Wei

    2003-11-01

    In smart structure applications where fiber sensors are embedded within structural materials, multiple lead in/out fibers are preferred for redundancy and improving reliability. The use of only one lead/out fiber is not optimal because the breakage of a fiber at one location due to, for example, local structural damage, would cause the failure of the whole sensing system. The multiplexing and networking techniques suitable for such applications have attracted considerable research recently. In this article, based on the bidirectional interrogation technique for white light interferometric sensors arrays, a multiplexed fiber optic deformation sensor loop network suitable for smart structure applications has been designed and demonstrated. Loop-network sensor systems are based on the white light interferometric technique. Michelson and Mach-Zehnder optical path interrogators have been developed and demonstrated, respectively. For the usually used one direction interrogate sensing system, it is clear that multiplexed sensor arrays suffer from relatively large fiber segment-induced optical reflective and excess insertion loss that generally limit the total number of sensors that can be accommodated in this configuration. This loop-network bidirection interrogating technique greatly extended the multiplexing capacity of fiber optic white light interferometric sensors system. A practical implementation of this technique is presented which makes use of a popular light emitting diode, superluminescent diode, or amplified spontaneous emission optical light source and standard single mode fiber, which are commonly used in the communication industry. The sensor loop topology is completely passive and absolute length measurements can be obtained for each sensing fiber segment so that it can be used to measure quasidistribution strain or temperature. For large-scale smart structures, this technique not only extends the multiplexing potential, but also provides a redundancy for

  6. Integrating gravimetric and interferometric synthetic aperture radar data for enhancing reservoir history matching of carbonate gas and volatile oil reservoirs

    KAUST Repository

    Katterbauer, Klemens

    2016-08-25

    Reservoir history matching is assuming a critical role in understanding reservoir characteristics, tracking water fronts, and forecasting production. While production data have been incorporated for matching reservoir production levels and estimating critical reservoir parameters, the sparse spatial nature of this dataset limits the efficiency of the history matching process. Recently, gravimetry techniques have significantly advanced to the point of providing measurement accuracy in the microgal range and consequently can be used for the tracking of gas displacement caused by water influx. While gravity measurements provide information on subsurface density changes, i.e., the composition of the reservoir, these data do only yield marginal information about temporal displacements of oil and inflowing water. We propose to complement gravimetric data with interferometric synthetic aperture radar surface deformation data to exploit the strong pressure deformation relationship for enhancing fluid flow direction forecasts. We have developed an ensemble Kalman-filter-based history matching framework for gas, gas condensate, and volatile oil reservoirs, which synergizes time-lapse gravity and interferometric synthetic aperture radar data for improved reservoir management and reservoir forecasts. Based on a dual state-parameter estimation algorithm separating the estimation of static reservoir parameters from the dynamic reservoir parameters, our numerical experiments demonstrate that history matching gravity measurements allow monitoring the density changes caused by oil-gas phase transition and water influx to determine the saturation levels, whereas the interferometric synthetic aperture radar measurements help to improve the forecasts of hydrocarbon production and water displacement directions. The reservoir estimates resulting from the dual filtering scheme are on average 20%-40% better than those from the joint estimation scheme, but require about a 30% increase in

  7. Crowdsourced online dispute resolution

    NARCIS (Netherlands)

    Dimov, D.V.

    2017-01-01

    Solving disputes often takes a considerable amount of time and money. That holds for everyone involved. A new type of dispute resolution called Crowdsourced Online Dispute Resolution (CODR) seems to have the potential to offer a cheap, fast, and democratic dispute resolution procedure. Since it is

  8. A comparison measurement of nonlinear ultrasonic waves in tubes by a microphone and by an optical interferometric probe.

    Science.gov (United States)

    Slegrová, Zuzana; Bálek, Rudolf

    2005-03-01

    This paper deals with the analysis of ultrasonic fields inside waveguides generated by ultrasonic waves of high amplitude. These waves behave nonlinearly, so it is not possible to use standard linear equations to describe their behaviour. Therefore, we started with an experimental determination of the acoustic pressure of air in glass tubes. We chose two methods of measurement--by a microphone and by an optical interferometric probe. The conventional method by a microphone creates numerous problems, which can be avoided by using an optical method, a heterodyne laser interferometer.

  9. Spatial Frequency Multiplexing of Fiber-Optic Interferometric Refractive Index Sensors Based on Graded-Index Multimode Fibers

    Science.gov (United States)

    Liu, Li; Gong, Yuan; Wu, Yu; Zhao, Tian; Wu, Hui-Juan; Rao, Yun-Jiang

    2012-01-01

    Fiber-optic interferometric sensors based on graded-index multimode fibers have very high refractive-index sensitivity, as we previously demonstrated. In this paper, spatial-frequency multiplexing of this type of fiber-optic refractive index sensors is investigated. It is estimated that multiplexing of more than 10 such sensors is possible. In the multiplexing scheme, one of the sensors is used to investigate the refractive index and temperature responses. The fast Fourier transform (FFT) of the combined reflective spectra is analyzed. The intensity of the FFT spectra is linearly related with the refractive index and is not sensitive to the temperature.

  10. Radio interferometric determination of intercontinental baselines and earth orientation utilizing deep space network antennas - 1971 to 1980

    Science.gov (United States)

    Sovers, O. J.; Thomas, J. B.; Fanselow, J. L.; Cohen, E. J.; Purcell, G. H., Jr.; Rogstad, D. H.; Skjerve, L. J.; Spitzmesser, D. J.

    1984-01-01

    Progress has been made toward the realization of the potential of radio interferometry for measuring crustal motions and global rotations of the earth with accuracies at the centimeter level. In this connection, a series of experiments, primarily with NASA's Deep Space Network (DSN) antennas, has been conducted to develop two generations of very long baseline interferometric (VLBI) systems. A description is presented of the employed techniques, an analysis of the experiments, and the results of geophysical significance. Attention is given to the interferometry technique, the geometric delay model, propagation media calibrations, and the observing strategy.

  11. Surface Ruptures and Building Damage of the 2003 Bam, Iran, Earthquake Mapped by Satellite Synthetic Aperture Radar Interferometric Correlation

    Science.gov (United States)

    Fielding, Eric J.; Talebian, M.; Rosen, P. A.; Nazari, H.; Jackson, J. A.; Ghorashi, M.; Walker, R.

    2005-01-01

    We use the interferometric correlation from Envisat synthetic aperture radar (SAR) images to map the details of the surface ruptures related to the 26 December 2003 earthquake that devastated Bam, Iran. The main strike-slip fault rupture south of the city of Bam has a series of four segments with left steps shown by a narrow line of low correlation in the coseismic interferogram. This also has a clear expression in the field because of the net extension across the fault. Just south of the city limits, the surface strain becomes distributed over a width of about 500 m, probably because of a thicker layer of soft sedimentary material.

  12. Swept-wavelength interferometric interrogation of fiber Rayleigh scatter for distributed sensing applications

    Science.gov (United States)

    Gifford, Dawn K.; Kreger, Steven T.; Sang, Alex K.; Froggatt, Mark E.; Duncan, Roger G.; Wolfe, Matthew S.; Soller, Brian J.

    2007-09-01

    We review recent advancements in making high resolution distributed strain and temperature measurements using swept-wavelength interferometry to observe the spectral characteristics of Rayleigh scatter in optical fibers. Current methods available for distributed strain or temperature sensing in optical fiber include techniques based on Raman, Brillouin, and Rayleigh scattering. These techniques typically employ optical time domain reflectometry and are thus limited in spatial resolution to 0.1 to 1 m. Fiber Bragg gratings can yield higher spatial resolution but are difficult to multiplex in large numbers for applications requiring wide scale coverage. Swept-wavelength interferometry allows the Rayleigh scatter amplitude and phase to be sampled with very high spatial resolution (10s of microns). The Rayleigh scatter complex amplitude can be Fourier Transformed to obtain the Rayleigh scatter optical spectrum and shifts in the spectral pattern can related to changes in strain or temperature. This technique results in distributed strain measurements with 1 μɛ resolution or temperature measurements with 0.1 C resolution. These measurements can be made with sub-cm spatial resolution over a 100 m measurement range or with sub-10 cm resolution over a 1 Km range. A principle advantage of this technique is that it does not require specialty fiber. Thus, measurements can be made in pre-installed single mode or multimode fibers, including those used for telecommunication networks. Applications range from fault monitoring in short range communications networks, structural health monitoring, shape sensing, pipeline and electrical transmission line monitoring, to perimeter security. Several examples are discussed in detail.

  13. Fabrication and Optimization of Bilayered Nanoporous Anodic Alumina Structures as Multi-Point Interferometric Sensing Platform

    Directory of Open Access Journals (Sweden)

    Mahdieh Nemati

    2018-02-01

    Full Text Available Herein, we present an innovative strategy for optimizing hierarchical structures of nanoporous anodic alumina (NAA to advance their optical sensing performance toward multi-analyte biosensing. This approach is based on the fabrication of multilayered NAA and the formation of differential effective medium of their structure by controlling three fabrication parameters (i.e., anodization steps, anodization time, and pore widening time. The rationale of the proposed concept is that interferometric bilayered NAA (BL-NAA, which features two layers of different pore diameters, can provide distinct reflectometric interference spectroscopy (RIfS signatures for each layer within the NAA structure and can therefore potentially be used for multi-point biosensing. This paper presents the structural fabrication of layered NAA structures, and the optimization and evaluation of their RIfS optical sensing performance through changes in the effective optical thickness (EOT using quercetin as a model molecule. The bilayered or funnel-like NAA structures were designed with the aim of characterizing the sensitivity of both layers of quercetin molecules using RIfS and exploring the potential of these photonic structures, featuring different pore diameters, for simultaneous size-exclusion and multi-analyte optical biosensing. The sensing performance of the prepared NAA platforms was examined by real-time screening of binding reactions between human serum albumin (HSA-modified NAA (i.e., sensing element and quercetin (i.e., analyte. BL-NAAs display a complex optical interference spectrum, which can be resolved by fast Fourier transform (FFT to monitor the EOT changes, where three distinctive peaks were revealed corresponding to the top, bottom, and total layer within the BL-NAA structures. The spectral shifts of these three characteristic peaks were used as sensing signals to monitor the binding events in each NAA pore in real-time upon exposure to different

  14. The use of Interferometric Microscopy to assess 3D modifications of deteriorated medieval glass.

    Science.gov (United States)

    Gentaz, L.; Lombardo, T.; Chabas, A.

    2012-04-01

    Due to low durability, Northern European medieval glass undergoes the action of the atmospheric environment leading in some cases to a state of dramatic deterioration. Modification features varies from a simple loss of transparency to a severe material loss. In order to understand the underlying mechanisms and preserve this heritage, fundamental research is necessary too. In this optic, field exposure of analogues and original stained glass was carried out to study the early stages of the glass weathering. Model glass and original stained glass (after removal of deterioration products) were exposed in real conditions in an urban site (Paris) for 48 months. A regular withdrawal of samples allowed a follow-up of short-term glass evolution. Morphological modifications of the exposed samples were investigated through conventional and non destructive microscopy, using respectively a Scanning Electron Microscope (SEM) and an Interferometric Microscope (IM). This latter allows a 3D quantification of the object with no sample preparation. For all glasses, both surface recession and build-up of deposit were observed as a consequence of a leaching process (interdiffusion of protons and glass cations). The build-up of a deposit comes from the reaction between the extracted glass cations and atmospheric gases. Instead, surface recession is due mainly to the formation of brittle layer of altered glass at the sub-surface, where a fracture network can appear, leading to the scaling of parts of this modified glass. Finally, dissolution of the glass takes place, inducing the formation of pits and craters. The arithmetic roughness (Ra) was used as an indicator of weathering increase, in order to evaluate the deterioration state. For instance, the Ra grew from few tens of nm for pristine glass to thousands of nm for scaled areas. This technique also allowed a precise quantification of dimensions (height, depth and width) of deposits and pits, and the estimation of their overall

  15. Gulf Coast Subsidence: Integration of Geodesy, Geophysical Modeling, and Interferometric Synthetic Aperture Radar Observations

    Science.gov (United States)

    Blom, R. G.; Chapman, B. D.; Deese, R.; Dokka, R. K.; Fielding, E. J.; Hawkins, B.; Hensley, S.; Ivins, E. R.; Jones, C. E.; Kent, J. D.; Liu, Z.; Lohman, R.; Zheng, Y.

    2012-12-01

    The vulnerability of the US Gulf Coast has received increased attention in the years since hurricanes Katrina and Rita. Agencies responsible for the long-term protection of lives and infrastructure require precise estimates of future subsidence and sea level rise. A quantitative, geophysically based methodology can provide such estimates by incorporating geological data, geodetic measurements, geophysical models of non-elastic mechanical behavior at depth, and geographically comprehensive deformation monitoring made possible with measurements from Interferometric Synthetic Aperture Radar (InSAR). To be effective, results must be available to user agencies in a format suitable for integration within existing decision-support processes. Work to date has included analysis of historical and continuing ground-based geodetic measurements. These reveal a surprising degree of complexity, including regions that are subsiding at rates faster than those considered for hurricane protection planning of New Orleans and other coastal communities (http://www.mvn.usace.army.mil/pdf/hps_verticalsettlement.pdf) as well as Louisiana's coastal restoration strategies (http://www.coast2050.gov/2050reports.htm) (Dokka, 2011, J. Geophys. Res., 116, B06403, doi:10.1029/2010JB008008). Traditional geodetic measurements provide precise information at single points, while InSAR observations provide geographically comprehensive measurements of surface deformation at lower vertical precision. Available InSAR data sources include X-, C- and L-band satellite, and NASA/JPL airborne UAVSAR L-band data. The Gulf Coast environment is very challenging for InSAR techniques, especially with systems not designed for interferometry. For example, the shorter wavelength C-band data decorrelates over short time periods requiring more elaborate time-series analysis techniques, with which we've had some success. Meanwhile, preliminary analysis of limited L-Band ALOS/PALSAR satellite data show promise

  16. Interferometric biosensing platform for multiplexed digital detection of viral pathogens and biomarkers

    Science.gov (United States)

    Daaboul, George

    Label-free optical biosensors have been established as proven tools for monitoring specific biomolecular interactions. However, compact and robust embodiments of such instruments have yet to be introduced in order to provide sensitive, quantitative, and high-throughput biosensing for low-cost research and clinical applications. Here we present the interferometric reflectance-imaging sensor (IRIS). IRIS allows sensitive label free analysis using an inexpensive and durable multi-color LED illumination source on a silicon based surface. IRIS monitors biomolecular interaction through measurement of biomass addition to the sensor's surface. We demonstrate the capability of this system to dynamically monitor antigen---antibody interactions with a noise floor of 5.2 pg/mm 2 and DNA single mismatch detection under isothermal melting conditions in an array format. Ensemble detection of binding events using IRIS did not provide the sensitivity needed for detection of infectious disease and biomarkers at clinically relevant concentrations. Therefore, a new approach was adapted to the IRIS platform that allowed the detection and identification of individual nanoparticles on the sensor's surface. The new detection method was termed single-particle IRIS (SP-IRIS). We developed two detection modalities for SP-IRIS. The first modality is when the target is a nanoparticle such as a virus. We verified that SP-IRIS can accurately detect and size individual viral particles. Then we demonstrated that single nanoparticle counting and sizing methodology on SP-IRIS leads to a specific and sensitive virus sensor that can be multiplexed. Finally, we developed an assay for the detection of Ebola and Marburg. A detection limit of 3 x 103 PFU/ml was demonstrated for vesicular stomatitis virus (VSV) pseudotyped with Ebola or Marburg virus glycoprotein. We have demonstrated that virus detection can be done in human whole blood directly without the need for sample preparation. The second modality

  17. Topics in LIGO-related physics: Interferometric speed meters and tidal work

    Science.gov (United States)

    Purdue, Patricia Marie

    In the quest to develop viable designs for third-generation interferometric gravitational-wave detectors (such as the Laser Interferometer Gravitational-Wave Observatory, LIGO), one strategy is monitoring the relative momentum or speed of the test-mass mirrors, rather than monitoring their relative position. The most straightforward design for a speed-meter interferometer that accomplishes this is analyzed in Chapter 2. It is shown that in principle this design can beat the standard quantum limit (SQL) by an arbitrarily large amount, over an arbitrarily wide range of frequencies. However, in practice, this specific speed meter requires exorbitantly high input light power. Chapter 3 proposes a more sophisticated version of a speed meter. This new design requires modest input power and appears to be a fully practical candidate for third-generation detectors. It can beat the SQL over a broad range of frequencies (˜10 to 100 Hz in practice) by a factor h/hSQL ˜ WSQLcirc/Wc irc . Here Wcirc is the light power circulating in the interferometer arms and WSQL ≃ 800 kW is the circulating power required to beat the SQL at 100 Hz. If squeezed vacuum (with a power-squeeze factor e-2 R) is injected into the interferometer's output port, the SQL can be beat with less laser power: h/h SQL ˜ WSQLcirc/Wc irce2R . For realistic parameters (e2 R ≃ 10 and Wcirc ≃ 800 kW), the SQL can be beat by a factor ˜3 from 10 to 100 Hz. By performing frequency-dependent homodyne detection on the output (using two kilometer-scale filter cavities), one can markedly improve the interferometer's sensitivity at frequencies above 100 Hz. Chapter 4 is a contribution to the foundations for analyzing sources of gravitational waves. Specifically, it presents an analysis of the tidal work done on a self-gravitating body in an external tidal field. By examining the change in the mass-energy of the body as a result of the tidal field, it is shown that the work done is gauge invariant, while the body

  18. Medida del coeficiente d33 de piezocomposites por interferometría láser

    Directory of Open Access Journals (Sweden)

    Montero de Espinosa, F.

    2002-02-01

    Full Text Available The measurement of piezoelectric coefficient d33 is made using devices like the Berlincourt Meter ®, based on a force generator internally calibrated by a reference piezoelectric element which measures the charge ratio Culomb/Newton. For estructures such as piezoelectric composites, formed by materials of very different elastic properties, the measurements made by the described system present a great dispersión which depends on both the size of the pressing head and the aplied arm pressure. This work presents a set of systematic measurements of d33 for several piezocomposite geometries by means of optical interferometry. These measurements are compared with those obtained with the Berlincourt. It is observed that both techniques render closer results as the net step is reduced.La medida del coeficiente piezoeléctrico d33 se realiza utilizando equipos como el Berlincourt Meter ®, basados en un generador de fuerza calibrado internamente por un elemento piezoeléctrico de referencia que mide la relación de carga, Culombio/ Newton. Estos sistemas están absolutamente contrastados, tomando los grupos de investigación sus medidas como estándar. En el caso de estructuras tales como los composites piezoeléctricos, en los que la estructura está formada por materiales de muy distinta elasticidad, bien por este hecho, bien por la misma estructura, las medidas con el sistema descrito presentan una gran dispersión dependiendo del tamaño de la cabeza presionante y la presión del brazo. Dado que en el modelado de resonadores piezocomposite para su uso en aplicaciones con acoplamiento en aire es necesario conocer dicho parámetro sin incertidumbre, se presentan en el trabajo una serie de medidas sistemáticas de dicho coeficiente para varias geometrías de piezocomposites utilizando interferometría óptica. Se relaciona así mismo estas medidas con el resultado obtenido con el equipo estándar antes referido observando como cuanto más pequeño es

  19. Time-series analysis of surface deformation at Brady Hot Springs geothermal field (Nevada) using interferometric synthetic aperture radar

    Energy Technology Data Exchange (ETDEWEB)

    Ali, S. T. [Univ. of Wisconsin, Madison, WI (United States); Akerley, J. [Ormat Technologies Inc., Reno, NV (United States); Baluyut, E. C. [Univ. of Wisconsin, Madison, WI (United States); Cardiff, M. [Univ. of Wisconsin, Madison, WI (United States); Davatzes, N. C. [Temple Univ., Philadelphia, PA (United States). Dept. of Earth and Environmental Science; Feigl, K. L. [Univ. of Wisconsin, Madison, WI (United States); Foxall, W. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Fratta, D. [Univ. of Wisconsin, Madison, WI (United States); Mellors, R. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Spielman, P. [Ormat Technologies Inc., Reno, NV (United States); Wang, H. F. [Univ. of Wisconsin, Madison, WI (United States); Zemach, E. [Ormat Technologies Inc., Reno, NV (United States)

    2016-05-01

    We analyze interferometric synthetic aperture radar (InSAR) data acquired between 2004 and 2014, by the ERS-2, Envisat, ALOS and TerraSAR-X/TanDEM-X satellite missions to measure and characterize time-dependent deformation at the Brady Hot Springs geothermal field in western Nevada due to extraction of fluids. The long axis of the ~4 km by ~1.5 km elliptical subsiding area coincides with the strike of the dominant normal fault system at Brady. Within this bowl of subsidence, the interference pattern shows several smaller features with length scales of the order of ~1 km. This signature occurs consistently in all of the well-correlated interferometric pairs spanning several months. Results from inverse modeling suggest that the deformation is a result of volumetric contraction in shallow units, no deeper than 600 m, likely associated with damaged regions where fault segments mechanically interact. Such damaged zones are expected to extend downward along steeply dipping fault planes, providing a high permeability conduit to the production wells. Using time series analysis, we test the hypothesis that geothermal production drives the observed deformation. We find a good correlation between the observed deformation rate and the rate of production in the shallow wells. We also explore mechanisms that could potentially cause the observed deformation, including thermal contraction of rock, decline in pore pressure and dissolution of minerals over time.

  20. Interferometric Water Level Tilt Meter Development in Finland and Comparison with Combined Earth Tide and Ocean Loading Models

    Science.gov (United States)

    Ruotsalainen, Hannu

    2017-05-01

    A modern third-generation interferometric water level tilt meter was developed at the Finnish Geodetic Institute in 2000. The tilt meter has absolute scale and can do high-precision tilt measurements on earth tides, ocean tide loading and atmospheric loading. Additionally, it can be applied in various kinds of geodynamic and geophysical research. The principles and results of the historical 100-year-old Michelson-Gale tilt meter, as well as the development of interferometric water tube tilt meters of the Finnish Geodetic Institute, Finland, are reviewed. Modern Earth tide model tilt combined with Schwiderski ocean tide loading model explains the uncertainty in historical tilt observations by Michelson and Gale. Earth tide tilt observations in Lohja2 geodynamic station, southern Finland, are compared with the combined model earth tide and four ocean tide loading models. The observed diurnal and semidiurnal harmonic constituents do not fit well with combined models. The reason could be a result of the improper harmonic modelling of the Baltic Sea tides in those models.

  1. Optimization of grating duty cycle in non-interferometric grating-based X-ray phase contrast imaging

    Science.gov (United States)

    Luo, Ronghui; Wu, Zhao; Xiong, Ying; Wei, Chenxi; Zhang, Xiaobo; Hu, Renfang; Wang, Lei; Guo, Liang; Liu, Gang; Tian, Yangchao

    2017-08-01

    Grating-based X-ray phase contrast imaging technology is one of the most potential imaging methods in real applications. It can be classified into two categories: interferometry and non-interferometric imaging. The non-interferometric grating-based X-ray phase contrast imaging (NIGPCI) instrument has a great advantage in the forthcoming commercial applications for the flexible system design and the use of large periodic gratings. The performance of the NIGPCI instrument depends on its angular sensitivity to a great extent. Therefore, good angular sensitivity is mandatory in order to obtain high quality phase-contrast images. Several parameters, such as the X-ray spectrum, the inter-grating distances, and the parameters of the three gratings, influence the angular sensitivity of the imaging system. However, the quantitative relationship between the angular sensitivity and grating duty cycle is unclear. Therefore, this paper is devoted to revealing their internal relation by theoretical deduction and emulation of the imaging process with the theories of linear system and Fourier optics. Furthermore, a quantitative analysis method to optimize the duty cycles of gratings is proposed and its applicability to a general NIGPCI system is verified.

  2. Smart pixel camera based signal processing in an interferometric test station for massive parallel inspection of MEMS and MOEMS

    Science.gov (United States)

    Styk, Adam; Lambelet, Patrick; Røyset, Arne; Kujawińska, Małgorzata; Gastinger, Kay

    2010-09-01

    The paper presents the electro-optical design of an interferometric inspection system for massive parallel inspection of Micro(Opto)ElectroMechanicalSystems (M(O)EMS). The basic idea is to adapt a micro-optical probing wafer to the M(O)EMS wafer under test. The probing wafer is exchangeable and contains a micro-optical interferometer array: a low coherent interferometer (LCI) array based on a Mirau configuration and a laser interferometer (LI) array based on a Twyman-Green configuration. The interference signals are generated in the micro-optical interferometers and are applied for M(O)EMS shape and deformation measurements by means of LCI and for M(O)EMS vibration analysis (the resonance frequency and spatial mode distribution) by means of LI. Distributed array of 5×5 smart pixel imagers detects the interferometric signals. The signal processing is based on the "on pixel" processing capacity of the smart pixel camera array, which can be utilised for phase shifting, signal demodulation or envelope maximum determination. Each micro-interferometer image is detected by the 140 × 146 pixels sub-array distributed in the imaging plane. In the paper the architecture of cameras with smart-pixel approach are described and their application for massive parallel electrooptical detection and data reduction is discussed. The full data processing paths for laser interferometer and low coherent interferometer are presented.

  3. High-resolution image reconstruction for GRIN rod lens probe (Conference Presentation)

    Science.gov (United States)

    Kim, Hyung-Jin; Park, Kwan Jun; Yang, Taeseok D.; Choi, Wonshik; Kim, Beop-Min; Choi, Youngwoon

    2017-02-01

    Graded-index (GRIN) lenses have been widely used for developing compact imaging devices due to the small dimensions and simple optics designs. GRIN lenses, however, have intrinsic aberration which causes a distortion of the image and thus are subject to limited resolution and blurred imaging quality. Here, we employ the high-precision wavefront measurement technique for compensation of the distortion of a GRIN lens to obtain a high-resolution and high-contrast image. In doing so, we demonstrate a high-resolution and ultra-thin endo-microscope using a GRIN. A reflection-type interferometric microscope through a GRIN lens was constructed using multiple lasers (473 nm, 532 nm, and 633 nm) as light sources. The characteristics of the aberration of the GRIN lens were measured using the digital holographic method. The distortion of the GRIN lens was removed by numerical image processing with the prior information from the pre-calibration. We apply this technique to a reflection image of biological tissues acquired by our custom-built GRIN lens probe. Consequently, a diffraction limited lateral resolution as well as improved axial resolution can be achieved. Our approach will facilitate the use of GRIN lenses for compact imaging devices without compromising optical resolution and image quality.

  4. Cold optics of MIDI : the mid-infrared interferometric instrument for the VLTI

    NARCIS (Netherlands)

    Pel, JW; Glazenborg-Kluttig, AW; de Haas, JCM; Hanenburg, H; Lenzen, R; Lena, PJ; Quirrenbach, A

    2000-01-01

    ESO's new Very Large Telescope will consist of four 8.2m telescopes and three moveable 1.8m telescopes. Light from these can be combined in the Very Large Telescope Interferometer (VLTI) providing milli-arcsecond resolution with high sensitivity. The VLTI will first operate in the infrared and will

  5. Experimental investigation at 10 Gb/s of the noise suppression capabilities in a pass-through configuration in SOA-based interferometric structures

    DEFF Research Database (Denmark)

    Wolfson, David; Fjelde, Tina; Kloch, Allan

    2000-01-01

    We experimentally investigate a pass-through scheme for all-optical noise suppression in a SOA-based interferometric structure at 10 Gb/s. An input power dynamic range of ~8 dB as well as a noise suppression capability of ~4.5 dB has been demonstrated. Furthermore, the transmission properties have...

  6. Experimental Verification of a New Model Describing the Influence of Incomplete Signal Extinction Ratio on the Sensitivity Degradation due to Multiple Interferometric Crosstalk

    DEFF Research Database (Denmark)

    Liu, Fenghai; Rasmussen, Christian Jørgen; Pedersen, Rune Johan Skullerud

    1999-01-01

    analytical relations for crosstalk induced power penalties are derived taking the signal extinction ratio into account and excellent agreement with 10-Gb/s experiments is obtained. Both theory and experiment show the importance of the signal extinction ratio in connection with interferometric crosstalk....

  7. A single-sided homogeneous Green's function representation for holographic imaging, inverse scattering, time-reversal acoustics and interferometric Green's function retrieval

    NARCIS (Netherlands)

    Wapenaar, C.P.A.; Thorbecke, J.W.; van der Neut, J.R.

    2016-01-01

    Green's theorem plays a fundamental role in a diverse range of wavefield imaging applications, such as holographic imaging, inverse scattering, time-reversal acoustics and interferometric Green's function retrieval. In many of those applications, the homogeneous Green's function (i.e. the Green's

  8. Bank Resolution in Europe

    DEFF Research Database (Denmark)

    N. Gordon, Jeffery; Ringe, Georg

    2015-01-01

    Bank resolution is a key pillar of the European Banking Union. This column argues that the current structure of large EU banks is not conducive to an effective and unbiased resolution procedure. The authors would require systemically important banks to reorganise into a ‘holding company’ structure...

  9. abour Dispute Resolution System

    African Journals Online (AJOL)

    for Conciliation, Mediation and Arbitration (CCMA). Even though the Labour. Relations Act 66/95 (LRA) has brought statutory dispute resolution within reach of the ordinary worker, it might actually have compounded the problems relating to dispute resolution in the country. The high rate of individual unfair dismissal cases ...

  10. Automated conflict resolution issues

    Science.gov (United States)

    Wike, Jeffrey S.

    1991-01-01

    A discussion is presented of how conflicts for Space Network resources should be resolved in the ATDRSS era. The following topics are presented: a description of how resource conflicts are currently resolved; a description of issues associated with automated conflict resolution; present conflict resolution strategies; and topics for further discussion.

  11. What causes the large extensions of red supergiant atmospheres?. Comparisons of interferometric observations with 1D hydrostatic, 3D convection, and 1D pulsating model atmospheres

    Science.gov (United States)

    Arroyo-Torres, B.; Wittkowski, M.; Chiavassa, A.; Scholz, M.; Freytag, B.; Marcaide, J. M.; Hauschildt, P. H.; Wood, P. R.; Abellan, F. J.

    2015-03-01

    Aims: This research has two main goals. First, we present the atmospheric structure and the fundamental parameters of three red supergiants (RSGs), increasing the sample of RSGs observed by near-infrared spectro-interferometry. Additionally, we test possible mechanisms that may explain the large observed atmospheric extensions of RSGs. Methods: We carried out spectro-interferometric observations of the RSGs V602 Car, HD 95687, and HD 183589 in the near-infrared K-band (1.92-2.47 μm) with the VLTI/AMBER instrument at medium spectral resolution (R ~ 1500). To categorize and comprehend the extended atmospheres, we compared our observational results to predictions by available hydrostatic PHOENIX, available 3D convection, and new 1D self-excited pulsation models of RSGs. Results: Our near-infrared flux spectra of V602 Car, HD 95687, and HD 183589 are well reproduced by the PHOENIX model atmospheres. The continuum visibility values are consistent with a limb-darkened disk as predicted by the PHOENIX models, allowing us to determine the angular diameter and the fundamental parameters of our sources. Nonetheless, in the case of V602 Car and HD 95686, the PHOENIX model visibilities do not predict the large observed extensions of molecular layers, most remarkably in the CO bands. Likewise, the 3D convection models and the 1D pulsation models with typical parameters of RSGs lead to compact atmospheric structures as well, which are similar to the structure of the hydrostatic PHOENIX models. They can also not explain the observed decreases in the visibilities and thus the large atmospheric molecular extensions. The full sample of our RSGs indicates increasing observed atmospheric extensions with increasing luminosity and decreasing surface gravity, and no correlation with effective temperature or variability amplitude. Conclusions: The location of our RSG sources in the Hertzsprung-Russell diagram is confirmed to be consistent with the red limits of recent evolutionary tracks

  12. Resolving Phase Ambiguities in the Calibration of Redundant Interferometric Arrays: Implications for Array Design (Preprint)

    Science.gov (United States)

    2016-02-29

    tele - scopes in the array. Therefore with interferometry one can achieve the same high resolution offered by an extremely ? Email: bkurien@ll.mit.edu...of the telescope positions, which is known as a baseline. For an array of N apertures, the data set then consists of all ( N 2 ) such measurements. A...the United States Government. Binoy Kurien would like to acknowledge the MATLAB- based software package NUFFT (Fessler 2003) developed by Prof. Jeff

  13. Reflectance-mode interferometric near-infrared spectroscopy quantifies brain absorption, scattering, and blood flow index in vivo.

    Science.gov (United States)

    Borycki, Dawid; Kholiqov, Oybek; Srinivasan, Vivek J

    2017-02-01

    Interferometric near-infrared spectroscopy (iNIRS) is a new technique that measures time-of-flight- (TOF-) resolved autocorrelations in turbid media, enabling simultaneous estimation of optical and dynamical properties. Here, we demonstrate reflectance-mode iNIRS for noninvasive monitoring of a mouse brain in vivo. A method for more precise quantification with less static interference from superficial layers, based on separating static and dynamic components of the optical field autocorrelation, is presented. Absolute values of absorption, reduced scattering, and blood flow index (BFI) are measured, and changes in BFI and absorption are monitored during a hypercapnic challenge. Absorption changes from TOF-resolved iNIRS agree with absorption changes from continuous wave NIRS analysis, based on TOF-integrated light intensity changes, an effective path length, and the modified Beer-Lambert Law. Thus, iNIRS is a promising approach for quantitative and noninvasive monitoring of perfusion and optical properties in vivo.

  14. Evidence for on-going inflation of the Socorro Magma Body, New Mexico, from interferometric synthetic aperture radar imaging

    Science.gov (United States)

    Fialko, Yuri; Simons, Mark

    Interferometric synthetic aperture radar (InSAR) imaging of the central Rio Grande rift (New Mexico, USA) during 1992-1999 reveals a crustal uplift of several centimeters that spatially coincides with the seismologically determined outline of the Socorro magma body, one of the largest currently active magma intrusions in the Earth’s continental crust. Modeling of interferograms shows that the observed deformation may be due to elastic opening of a sill-like intrusion at a rate of a few millimeters per year. Despite an apparent constancy of the geodetically determined uplift rate, thermodynamic arguments suggest that it is unlikely that the Socorro magma body has formed via steady state elastic inflation.

  15. Complete chirp analysis of a gain-switched pulse using an interferometric two-photon absorption autocorrelation.

    Science.gov (United States)

    Chin, Sang Hoon; Kim, Young Jae; Song, Ho Seong; Kim, Dug Young

    2006-10-10

    We propose a simple but powerful scheme for the complete analysis of the frequency chirp of a gain-switched optical pulse using a fringe-resolved interferometric two-photon absorption autocorrelator. A frequency chirp imposed on the gain-switched pulse from a laser diode was retrieved from both the intensity autocorrelation trace and the envelope of the second-harmonic interference fringe pattern. To verify the accuracy of the proposed phase retrieval method, we have performed an optical pulse compression experiment by using dispersion-compensating fibers with different lengths. We have obtained close agreement by less than a 1% error between the compressed pulse widths and numerically calculated pulse widths.

  16. A novel positioning method for dual Mach-Zehnder interferometric vibration sensor in submarine cable security application

    Science.gov (United States)

    Xie, Shangran; Zhang, Min; Li, Yanhe; Liao, Yanbiao

    2011-05-01

    Dual Mach-Zehnder interferometric vibration sensor is an appropriate solution for submarine cable security application. While in this application the detected vibration signal is always narrow-bandwidth and short-duration subject to environmental constraints, which makes correlation based vibration positioning algorithm a poor robustness to noise. A preprocessing method focusing on expanding signal 3dB bandwidth before correlation is proposed in purpose of reducing ultimate positioning mean square error. A high pass filter is imposed to enhance the weight of high frequency components by attenuating low frequency main lobe. Field test results indicate a significant positioning error reduction when using this novel method as long as the cutoff frequency of high pass filter is selected in a valid region where positive effect of bandwidth extension is larger than effect of SNR reduction, and MSE reduction value in valid region agrees well with theoretical prediction.

  17. Gravitational Wave (GW Classification, Space GW Detection Sensitivities and AMIGO (Astrodynamical Middle-frequency Interferometric GW Observatory

    Directory of Open Access Journals (Sweden)

    Ni Wei-Tou

    2018-01-01

    Full Text Available After first reviewing the gravitational wave (GW spectral classification. we discuss the sensitivities of GW detection in space aimed at low frequency band (100 nHz–100 mHz and middle frequency band (100 mHz–10 Hz. The science goals are to detect GWs from (i Supermassive Black Holes; (ii Extreme-Mass-Ratio Black Hole Inspirals; (iii Intermediate-Mass Black Holes; (iv Galactic Compact Binaries; (v Stellar-Size Black Hole Binaries; and (vi Relic GW Background. The detector proposals have arm length ranging from 100 km to 1.35×109 km (9 AU including (a Solar orbiting detectors and (b Earth orbiting detectors. We discuss especially the sensitivities in the frequency band 0.1-10 μHz and the middle frequency band (0.1 Hz–10 Hz. We propose and discuss AMIGO as an Astrodynamical Middlefrequency Interferometric GW Observatory.

  18. Resolution exchange simulation.

    Science.gov (United States)

    Lyman, Edward; Ytreberg, F Marty; Zuckerman, Daniel M

    2006-01-20

    We extend replica-exchange simulation in two ways and apply our approaches to biomolecules. The first generalization permits exchange simulation between models of differing resolution--i.e., between detailed and coarse-grained models. Such "resolution exchange" can be applied to molecular systems or spin systems. The second extension is to "pseudoexchange" simulations, which require little CPU usage for most levels of the exchange ladder and also substantially reduce the need for overlap between levels. Pseudoexchanges can be used in either replica or resolution exchange simulations. We perform efficient, converged simulations of a 50-atom peptide to illustrate the new approaches.

  19. Model Accuracy Comparison for High Resolution Insar Coherence Statistics Over Urban Areas

    Science.gov (United States)

    Zhang, Yue; Fu, Kun; Sun, Xian; Xu, Guangluan; Wang, Hongqi

    2016-06-01

    The interferometric coherence map derived from the cross-correlation of two complex registered synthetic aperture radar (SAR) images is the reflection of imaged targets. In many applications, it can act as an independent information source, or give additional information complementary to the intensity image. Specially, the statistical properties of the coherence are of great importance in land cover classification, segmentation and change detection. However, compared to the amount of work on the statistical characters of SAR intensity, there are quite fewer researches on interferometric SAR (InSAR) coherence statistics. And to our knowledge, all of the existing work that focuses on InSAR coherence statistics, models the coherence with Gaussian distribution with no discrimination on data resolutions or scene types. But the properties of coherence may be different for different data resolutions and scene types. In this paper, we investigate on the coherence statistics for high resolution data over urban areas, by making a comparison of the accuracy of several typical statistical models. Four typical land classes including buildings, trees, shadow and roads are selected as the representatives of urban areas. Firstly, several regions are selected from the coherence map manually and labelled with their corresponding classes respectively. Then we try to model the statistics of the pixel coherence for each type of region, with different models including Gaussian, Rayleigh, Weibull, Beta and Nakagami. Finally, we evaluate the model accuracy for each type of region. The experiments on TanDEM-X data show that the Beta model has a better performance than other distributions.

  20. LHCb VELO Tracking Resolutions

    CERN Multimedia

    Alexander, Michael

    2011-01-01

    The excellent tracking performance of the Vertex Locator (VELO) at LHCb is presented. The resolutions it achieves on single hits, impact parameters, and primary vertex positions are shown, with particular attention paid to measurement of impact parameters.

  1. High Resolution Elevation Contours

    Data.gov (United States)

    Minnesota Department of Natural Resources — This dataset contains contours generated from high resolution data sources such as LiDAR. Generally speaking this data is 2 foot or less contour interval.

  2. Comparison study of Lightning VHF interferometric and LF time-of-arival maps

    Science.gov (United States)

    Kudo, A.; Stock, M.; Kawasaki, Z.; Ushio, T.

    2016-12-01

    Lightning discharges radiate broad band frequency electromagnetic waves from ULF to UHF. Using sensors which detect this radiation is an effective technique to detect lightning flashes, even if they are in a cloud. If multiple sensors are present, a lightning flash can be located using various techniques. At low frequencies, the power radiated by lightning is very high, but because the wavelengths are long, the location resolution is somewhat low. At very high frequencies, the wavelengths are much shorter allowing for much better location resolution, but the power radiation is also much lower, making it more difficult to detect. The VHF band is a good compromise between good location resolution, and good detection efficiency. One technique to locate VHF signals from lightning is interferometry. Using this technique, the signals arriving at three or more VHF broadband antennas are coherently combined to produce an image of the lightning flash. The current generation broadband lightning interferometer being developed in Japan by RAIRAN and the University of Osaka called Lightning Interferometer via VHF Emission (LIVE). Currently, LIVE is installed in Kaizuka, a city to the south of Osaka, near Osaka Bay to observe Japanese summer lightning. In the current study, we are comparing the high detail, 2-dimensional lightning maps produced by LIVE to the lower detail, 3-dimensional maps produced by a low frequency time-of-arrival system called the Broadband Observation network for Lightning and Thunderstorms (BOLT). In order to better compare the data, a new GPS timing device is being developed for LIVE to allow high absolute timing accuracy without sacrificing one of the 4 high speed digitizer channels. The objectives of the study are to better understand Japanese summer lightning, and to prepare for a future campaign as part of the GLM validation study.

  3. Scalable Resolution Display Walls

    KAUST Repository

    Leigh, Jason

    2013-01-01

    This article will describe the progress since 2000 on research and development in 2-D and 3-D scalable resolution display walls that are built from tiling individual lower resolution flat panel displays. The article will describe approaches and trends in display hardware construction, middleware architecture, and user-interaction design. The article will also highlight examples of use cases and the benefits the technology has brought to their respective disciplines. © 1963-2012 IEEE.

  4. Ultra high resolution tomography

    Energy Technology Data Exchange (ETDEWEB)

    Haddad, W.S.

    1994-11-15

    Recent work and results on ultra high resolution three dimensional imaging with soft x-rays will be presented. This work is aimed at determining microscopic three dimensional structure of biological and material specimens. Three dimensional reconstructed images of a microscopic test object will be presented; the reconstruction has a resolution on the order of 1000 A in all three dimensions. Preliminary work with biological samples will also be shown, and the experimental and numerical methods used will be discussed.

  5. Dynamic systemic resolution.

    Science.gov (United States)

    Sakulsombat, Morakot; Zhang, Yan; Ramström, Olof

    2012-01-01

    Dynamic Systemic Resolution is a powerful technique for selecting optimal constituents from dynamic systems by applying selection pressures, either externally by addition of target entities, or internally within the system constraints. This concept is a subset of Constitutional Dynamic Chemistry, and the dynamic systems are generally based on reversible covalent interactions between a range of components where the systems are maintained under thermodynamic control. In the present chapter, the concept will be described in detail, and a range of examples will be given for both selection classes. For external pressure generation, target enzymes, in aqueous and/or organic solution, have been used to demonstrate the resolution processes. In a first example, a dynamic transthiolesterification system was generated in aqueous solution at neutral pH, and resolved by hydrolysis using serine hydrolases (cholinesterases). In organic solution, lipase-catalyzed acylation was chosen to demonstrate asymmetric resolution in different dynamic systems, generating chiral ester and amide structures. By use of such biocatalysts, the optimal constituents were selectively chosen and amplified from the dynamic systems in one-pot processes. In internal selection pressure resolution, self-transformation and crystallization-induced diastereomeric resolution have been successfully used to challenge dynamic systems. The technique was, for example, used to identify the best diastereomeric substrate from a large and varied dynamic system in a single resolution reaction.

  6. Conflict Prevention and Resolution Center

    Science.gov (United States)

    The Conflict Prevention and Resolution Center is EPA's primary resource for services and expertise in the areas of consensus-building, collaborative problem solving, alternative dispute resolution, and environmental collaboration and conflict resolution.

  7. Laser heterodyne interferometric signal processing method based on rising edge locking with high frequency clock signal.

    Science.gov (United States)

    Zhang, Enzheng; Chen, Benyong; Yan, Liping; Yang, Tao; Hao, Qun; Dong, Wenjun; Li, Chaorong

    2013-02-25

    A novel phase measurement method composed of the rising-edge locked signal processing and the digital frequency mixing is proposed for laser heterodyne interferometer. The rising-edge locked signal processing, which employs a high frequency clock signal to lock the rising-edges of the reference and measurement signals, not only can improve the steepness of the rising-edge, but also can eliminate the error counting caused by multi-rising-edge phenomenon in fringe counting. The digital frequency mixing is realized by mixing the digital interference signal with a digital base signal that is different from conventional frequency mixing with analogue signals. These signal processing can improve the measurement accuracy and enhance anti-interference and measurement stability. The principle and implementation of the method are described in detail. An experimental setup was constructed and a series of experiments verified the feasibility of the method in large displacement measurement with high speed and nanometer resolution.

  8. Interferometric Spectroscopy of Scattered Light Can Quantify the Statistics of Subdiffractional Refractive-Index Fluctuations

    Science.gov (United States)

    Cherkezyan, L.; Capoglu, I.; Subramanian, H.; Rogers, J. D.; Damania, D.; Taflove, A.; Backman, V.

    2013-07-01

    Despite major importance in physics, biology, and other sciences, the optical sensing of nanoscale structures in the far zone remains an open problem due to the fundamental diffraction limit of resolution. We establish that the expected value of spectral variance (Σ˜2) of a far-field, diffraction-limited microscope image can quantify the refractive-index fluctuations of a label-free, weakly scattering sample at subdiffraction length scales. We report the general expression of Σ˜ for an arbitrary refractive-index distribution. For an exponential refractive-index spatial correlation, we obtain a closed-form solution of Σ˜ that is in excellent agreement with three-dimensional finite-difference time-domain solutions of Maxwell’s equations. Sensing complex inhomogeneous media at the nanoscale can benefit fields from material science to medical diagnostics.

  9. The nature of stars with the B[e] phenomenon through interferometric eyes

    Science.gov (United States)

    Borges Fernandes, M.

    2010-02-01

    Stars that present the B[e] phenomenon are known to form a heterogeneous group. This group is composed by objects in different evolutionary stages, like high- and low-mass evolved stars, intermediate-mass pre-main sequence stars and symbiotic objects. However, for more than 50% of the confirmed B[e] stars the evolutionary stage is still unknown, so that they are gathered in the group of the unclassified B[e] stars. High-angular resolution interferometry is certainly an important tool to answer questions related to the circumstellar geometry of these objects. In this work, we present the results related to seven objects, based on observations from VLTI/MIDI, VLTI/AMBER and CHARA/VEGA.

  10. Observing Turbulent Fragmentation In Simulations: Through the Looking Glass of CARMA and ALMA

    Science.gov (United States)

    Offner, Stella; Capodilupo, J.; Schnee, S.; Goodman, A.

    2012-01-01

    We use the CASA software package to synthetically observe binaries forming as a result of turbulent fragmentation in a radiation-hydrodynamic simulation of a collapsing molecular cloud. By following the evolution of such pairs beginning in the prestellar core stage, we are able to make predictions about the feasibility of observing such fragmentation using the Combined Array for Research in Millimeter-wave Astronomy (CARMA) and the Atacama Large Millimeter/submillimeter Array (ALMA). We find that while intermediate ALMA configurations may potentially resolve structure with one fourth the integration time of CARMA, both instruments only marginally resolve sub-structure within 25 kyr of the onset of gravitational collapse. In addition, interferometric spatial filtering significantly reduces traces of filamentary gas morphology on < 0.1 pc scales. Thus, even with the improved sub-arcsecond resolution of ALMA, constraining stellar multiplicity at the earliest stages of star formation will be challenging.

  11. Interferometric comparison of the performance of a CMOS and sCMOS detector

    Science.gov (United States)

    Flores-Moreno, J. M.; De la Torre I., Manuel H.; Hernández-Montes, M. S.; Pérez-López, Carlos; Mendoza S., Fernando

    2015-08-01

    We present an analysis of the imaging performance of two state-of-the-art sensors widely used in the nondestructive- testing area (NDT). The analysis is based on the quantification of the signal-to-noise (SNR) ratio from an optical phase image. The calculation of the SNR is based on the relation of the median (average) and standard deviation measurements over specific areas of interest in the phase images of both sensors. This retrieved phase is coming from the vibrational behavior of a large object by means of an out-of-plane holographic interferometer. The SNR is used as a figure-of-merit to evaluate and compare the performance of the CMOS and scientific CMOS (sCMOS) camera as part of the experimental set-up. One of the cameras has a high speed CMOS sensor while the other has a high resolution sCMOS sensor. The object under study is a metallically framed table with a Formica cover with an observable area of 1.1 m2. The vibration induced to the sample is performed by a linear step motor with an attached tip in the motion stage. Each camera is used once at the time to record the deformation keeping the same experimental conditions for each case. These measurements may complement the conventional procedures or technical information commonly used to evaluate a camerás performance such as: quantum efficiency, spatial resolution and others. Results present post processed images from both cameras, but showing a smoother and easy to unwrap optical phase coming from those recorded with the sCMOS camera.

  12. An accelerated splitting algorithm for radio-interferometric imaging: when natural and uniform weighting meet

    Science.gov (United States)

    Onose, Alexandru; Dabbech, Arwa; Wiaux, Yves

    2017-07-01

    Next-generation radio interferometers, like the Square Kilometre Array, will acquire large amounts of data with the goal of improving the size and sensitivity of the reconstructed images by orders of magnitude. The efficient processing of large-scale data sets is of great importance. We propose an acceleration strategy for a recently proposed primal-dual distributed algorithm. A preconditioning approach can incorporate into the algorithmic structure both the sampling density of the measured visibilities and the noise statistics. Using the sampling density information greatly accelerates the convergence speed, especially for highly non-uniform sampling patterns, while relying on the correct noise statistics optimizes the sensitivity of the reconstruction. In connection to clean, our approach can be seen as including in the same algorithmic structure both natural and uniform weighting, thereby simultaneously optimizing both the resolution and the sensitivity. The method relies on a new non-Euclidean proximity operator for the data fidelity term, that generalizes the projection on to the ℓ2 ball where the noise lives for naturally weighted data, to the projection on to a generalized ellipsoid incorporating sampling density information through uniform weighting. Importantly, this non-Euclidean modification is only an acceleration strategy to solve the convex imaging problem with data fidelity dictated only by noise statistics. We show through simulations with realistic sampling patterns the acceleration obtained using the preconditioning. We also investigate the algorithm performance for the reconstruction of the 3C129 radio galaxy from real visibilities and compare with multiscale clean, showing better sensitivity and resolution. Our matlab code is available online on GitHub.

  13. Resolution and termination

    Directory of Open Access Journals (Sweden)

    Adina FOLTIŞ

    2012-01-01

    Full Text Available The resolution, the termination and the reduction of labour conscription are regulated by articles 1549-1554 in the new Civil Code, which represents the common law in this matter. We appreciate that the new regulation does not conclusively clarify the issue related to whether the existence of liability in order to call upon the resolution is necessary or not, because the existence of this condition has been inferred under the previous regulation from the fact that the absence of liability shifts the inexecution issue on the domain of fortuitous impossibility of execution, situation in which the resolution of the contract is not in question, but that of the risk it implies.

  14. Applications of Polarimetric and Interferometric SAR to Environmental Remote Sensing and its Activities: Recent Advances in Extrawideband Polarimetry, Interferometry and Polarimetric Interferometry in Synthetic Aperture Remote Sensing and its Applications

    Science.gov (United States)

    2007-02-01

    is the “Multiple Signal Classification ( MUSIC )” technique introduced by R. O. Schmidt [225], which is based on an eigenvector/eigenvalue...interferometric and the polarimetric-interferometric radar and SAR cases [99, 225]. This MUSIC algorithm was applied successfully in telecommunications...Of Photogrammetry and Remote Sensing, vol.56 (2), pp.81-99, December 2001. [112] Imhoff, M.L., M. King, and C. Parkinson , 2002, “NASA’s Earth

  15. Lensfree Spectral Light-field Fusion Microscopy for Contrast- and Resolution-enhanced Imaging of Biological Specimens

    CERN Document Server

    Kazemzadeh, Farnoud; Molladavoodi, Sara; Mei, Yu; Emelko, Monica B; Gorbet, Maud B; Wong, Alexander

    2015-01-01

    A lensfree spectral light-field fusion microscopy (LSLFM) system is presented for enabling contrast- and resolution-enhanced imaging of biological specimens. LSLFM consists of a pulsed multispectral lensfree microscope for capturing interferometric light-field encodings at different wavelengths, and Bayesian-based fusion to reconstruct a fused object light-field from the encodings. By fusing unique object detail information captured at different wavelengths, LSLFM can achieve improved resolution, contrast, and signal-to-noise ratio (SNR) over a single-channel lensfree microscopy system. A five-channel LSLFM system was developed and quantitatively evaluated to validate the design. Experimental results demonstrated that the LSLFM system provided SNR improvements of 6.81-16.55 dB, as well as a six-fold improvement in the dispersion index (DI), over that achieved using a single-channel lensfree deconvolution microscopy system at individual wavelengths. Furthermore, the LSLFM system achieved an increase in numeric...

  16. Two color multichannel heterodyne interferometer set up for high spatial resolution electron density profile measurements in TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Pedreira, P.; Criado, A. R.; Acedo, P. [Department of Electronics Technology, Universidad Carlos III de Madrid, Leganes, Madrid 28911 (Spain); Esteban, L.; Sanchez, M.; Sanchez, J. [Laboratorio Nacional de Fusion por ConfinamientoMagnetico-CIEMAT, Madrid 28040 (Spain)

    2010-10-15

    A high spatial resolution two color [CO{sub 2}, {lambda}=10.6 {mu}m/Nd:YAG (Nd:YAG denotes neodymium-doped yttrium aluminum garnet), and {lambda}=1.064 {mu}m] expanded-beam multichannel heterodyne interferometer has been installed on the TJ-II stellarator. Careful design of the optical system has allowed complete control on the evolution of both Gaussian beams along the interferometer, as well as the evaluation and optimization of the spatial resolution to be expected in the measurements. Five CO{sub 2} (measurement) channels and three Nd:YAG (vibration compensation) channels have been used to illuminate the plasma with a probe beam of 100 mm size. An optimum interpolation method has been applied to recover both interferometric phasefronts prior to mechanical vibration subtraction. The first results of the installed diagnostic are presented in this paper.

  17. A neural network-based approach to noise identification of interferometric GW antennas: the case of the 40 m Caltech laser interferometer

    CERN Document Server

    Acernese, F; Rosa, M D; Rosa, R D; Eleuteri, A; Milano, L; Tagliaferri, R

    2002-01-01

    In this paper, a neural network-based approach is presented for the real time noise identification of a GW laser interferometric antenna. The 40 m Caltech laser interferometer output data provide a realistic test bed for noise identification algorithms because of the presence of many relevant effects: violin resonances in the suspensions, main power harmonics, ring-down noise from servo control systems, electronic noises, glitches and so on. These effects can be assumed to be present in all the first interferometric long baseline GW antennas such as VIRGO, LIGO, GEO and TAMA. For noise identification, we used the Caltech-40 m laser interferometer data. The results we obtained are pretty good notwithstanding the high initial computational cost. The algorithm we propose is general and robust, taking into account that it does not require a priori information on the data, nor a precise model, and it constitutes a powerful tool for time series data analysis.

  18. Fiber optic sensor for H2 gas detection in the presence of methane based on Pd/WO3 low-coherence interferometric structure

    Science.gov (United States)

    Maciak, Erwin

    2017-08-01

    In this paper I report the preparation and characterisation of an improved hydrogen gas sensor with a better sensitivity, using an amorphous thin WO3 film covered Pd film. Using a very sensitive optical sensing technique, such as the interference phenomena and a special configuration of the sensing structure were obtained interested results showing the influence of H2 gas on the optical sensor response. I present the design and results for an interferometric fiber optic hydrogen gas sensor, the Intrinsic Fabry-Perot Interferometer (IFPI), which uses the changing properties of layered interferometric sensing structure Pd/WO3 to detect hydrogen gas concentrations in the 500 - 2,000 ppm in synthetic dry air, with the working temperature at 80 °C in the presence of CH4.

  19. A neural network-based approach to noise identification of interferometric GW antennas: the case of the 40 m Caltech laser interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Acernese, F [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II, Complesso Universitario di Monte S Angelo, via Cintia, I-80126 Naples (Italy); Barone, F [Istituto Nazionale di Fisica Nucleare, sez. Napoli, Complesso Universitario di Monte S Angelo, via Cintia, I-80126 Naples (Italy); Rosa, M de [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II, Complesso Universitario di Monte S Angelo, via Cintia, I-80126 Naples (Italy); Rosa, R De [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II, Complesso Universitario di Monte S Angelo, via Cintia, I-80126 Naples (Italy); Eleuteri, A [Istituto Nazionale di Fisica Nucleare, sez. Napoli, Complesso Universitario di Monte S Angelo, via Cintia, I-80126 Naples (Italy); Milano, L [Dipartimento di Scienze Fisiche, Universita di Napoli Federico II, Complesso Universitario di Monte S Angelo, via Cintia, I-80126 Naples (Italy); Tagliaferri, R [Dipartimento di Matematica ed Informatica, Universita di Salerno, via S Allende, I-84081 Baronissi (Salerno) (Italy)

    2002-06-21

    In this paper, a neural network-based approach is presented for the real time noise identification of a GW laser interferometric antenna. The 40 m Caltech laser interferometer output data provide a realistic test bed for noise identification algorithms because of the presence of many relevant effects: violin resonances in the suspensions, main power harmonics, ring-down noise from servo control systems, electronic noises, glitches and so on. These effects can be assumed to be present in all the first interferometric long baseline GW antennas such as VIRGO, LIGO, GEO and TAMA. For noise identification, we used the Caltech-40 m laser interferometer data. The results we obtained are pretty good notwithstanding the high initial computational cost. The algorithm we propose is general and robust, taking into account that it does not require a priori information on the data, nor a precise model, and it constitutes a powerful tool for time series data analysis.

  20. A high-resolution radio image of a young supernova

    Energy Technology Data Exchange (ETDEWEB)

    Bartel, N.; Rupen, M.P.; Shapiro, I.I. (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA)); Preston, R.A. (Jet Propulsion Lab., Pasadena, CA (USA)); Rius, A. (Universidad Complutense de Madrid (Spain). Inst. de Astronomia y Geodesia)

    1991-03-21

    Supernovae in our own Galaxy are so rare that images of their remnants can show only the late aftermath of an explosion that occurred anything from a few hundred to several tens of thousands of years ago. Young supernovae are seen frequently in other galaxies, but because they are more distant it has not been possible until now to obtain high-resolution images that would reveal details of the explosion and the immediate development of the ejected material. Here we present a very-long-baseline interferometric (VLBI) radio image of the bright supernova 1986J, which occurred in the galaxy NGC891 at a distance of {similar to}12 Mpc. No detailed image of any supernova or remnant has been obtained before so soon after the explosion. Our image shows a shell of emission with jet-like protrusions. Their analysis should advance our understanding of the dynamics of the expanding debris, the dissipation of energy into the surrounding circumstellar medium, and the evolution of the supernova into the remnant. (author).

  1. The influence of technological mounting of lightweight large size space astronomical mirrors into the shape of its reflecting surface during interferometric control

    Science.gov (United States)

    Vlasenko, Oleg; Sachkov, Mikhail

    2016-07-01

    The technological mounting is necessary during the ground base tests to exclude the gravity influence into the lightweight large-size space astronomical mirrors (diameter of 1.7 m and more). We propose a method that allows to correct the influence of this mounting onto the mirror shape surface during an interferometric control. Here we present results based on primary mirror tests of the WSO-UV project.

  2. High resolution and stability roll angle measurement method for precision linear displacement stages

    Science.gov (United States)

    Jin, Tao; Xia, Guizheng; Hou, Wenmei; Le, Yanfen; Han, Sen

    2017-02-01

    A method for high resolution roll angle measurement of linear displacement stages is developed theoretically and tested experimentally. The new optical configuration is based on a special differential plane mirror interferometer, a wedge prism assembly, and a wedge mirror assembly. The wedge prisms assembly is used as a roll angle sensor, which converts roll angle to the changes of optical path. The special interferometer, composed a polarization splitter plane, a half wave plate, a beam splitter, a retro-reflector and a quarter wave plate, is designed for high resolution measurement of the changes of the optical path. The interferometric beams are a completely common path for the adoption of the centrosymmetrical measurement structure, and the cross talk of the straightness, yaw, and pitch errors is avoided. The angle measurement resolution of the proposed method is 3.5 μrad in theoretical with a phase meter which has a resolution of 2 π /512 . The experimental result also shows the great stability and accuracy of the present roll angle measurement system.

  3. Bank Resolution in Europe

    DEFF Research Database (Denmark)

    Gordon, Jeffrey N.; Ringe, Georg

    of taxpayer assistance. A holding company structure in which the public parent holds unsecured term debt sufficient to cover losses at an operating financial subsidiary would facilitate a “Single Point of Entry” resolution procedure that would minimize knock-on effects from the failure of a systemically...

  4. Bank Resolution in Europe

    DEFF Research Database (Denmark)

    N. Gordon, Jeffery; Ringe, Georg

    2015-01-01

    of taxpayer assistance. A holding company structure in which the public parent holds unsecured term debt sufficient to cover losses at an operating financial subsidiary would facilitate a “Single Point of Entry” resolution procedure that would minimize knock-on effects from the failure of a systemically...

  5. Review of interferometric spectroscopy of scattered light for the quantification of subdiffractional structure of biomaterials

    Science.gov (United States)

    Cherkezyan, Lusik; Zhang, Di; Subramanian, Hariharan; Capoglu, Ilker; Taflove, Allen; Backman, Vadim

    2017-03-01

    Optical microscopy is the staple technique in the examination of microscale material structure in basic science and applied research. Of particular importance to biology and medical research is the visualization and analysis of the weakly scattering biological cells and tissues. However, the resolution of optical microscopy is limited to ≥200 nm due to the fundamental diffraction limit of light. We review one distinct form of the spectroscopic microscopy (SM) method, which is founded in the analysis of the second-order spectral statistic of a wavelength-dependent bright-field far-zone reflected-light microscope image. This technique offers clear advantages for biomedical research by alleviating two notorious challenges of the optical evaluation of biomaterials: the diffraction limit of light and the lack of sensitivity to biological, optically transparent structures. Addressing the first issue, it has been shown that the spectroscopic content of a bright-field microscope image quantifies structural composition of samples at arbitrarily small length scales, limited by the signal-to-noise ratio of the detector, without necessarily resolving them. Addressing the second issue, SM utilizes a reference arm, sample arm interference scheme, which allows us to elevate the weak scattering signal from biomaterials above the instrument noise floor.

  6. In-vitro interferometric characterization of dynamic fluid layers on contact lenses

    Science.gov (United States)

    Primeau, Brian C.; Greivenkamp, John E.; Sullivan, John J.

    2011-08-01

    The anterior refracting surface of the eye when wearing a contact lens is the thin fluid layer that forms on the surface of the contact lens. Under normal conditions, this fluid layer is less than 10 microns thick. The fluid layer thickness and topography change over time and are affected by the material properties of the contact lens, and may affect vision quality and comfort. An in vitro method of characterizing dynamic fluid layers applied to contact lenses mounted on mechanical substrates has been developed using a phase-shifting Twyman-Green interferometer. This interferometer continuously measures light reflected from the surface of the fluid layer, allowing precision analysis of the dynamic fluid layer. Movies showing this fluid layer behavior can be generated. The fluid behavior on the contact lens surface is measured, allowing quantitative analysis beyond what typical contact angle or visual inspection methods provide. The interferometer system has measured the formation and break up of fluid layers. Different fluid and contact lens material combinations have been used, and significant fluid layer properties have been observed in some cases. The interferometer is capable of identifying features in the fluid layer less than a micron in depth with a spatial resolution of about ten microns. An area on the contact lens approximately 6 mm wide can be measured with the system. This paper will discuss the interferometer design and analysis methods used. Measurement results of different material and fluid combinations are presented.

  7. 3D beam shape estimation based on distributed coaxial cable interferometric sensor

    Science.gov (United States)

    Cheng, Baokai; Zhu, Wenge; Liu, Jie; Yuan, Lei; Xiao, Hai

    2017-03-01

    We present a coaxial cable interferometer based distributed sensing system for 3D beam shape estimation. By making a series of reflectors on a coaxial cable, multiple Fabry-Perot cavities are created on it. Two cables are mounted on the beam at proper locations, and a vector network analyzer (VNA) is connected to them to obtain the complex reflection signal, which is used to calculate the strain distribution of the beam in horizontal and vertical planes. With 6 GHz swept bandwidth on the VNA, the spatial resolution for distributed strain measurement is 0.1 m, and the sensitivity is 3.768 MHz mɛ -1 at the interferogram dip near 3.3 GHz. Using displacement-strain transformation, the shape of the beam is reconstructed. With only two modified cables and a VNA, this system is easy to implement and manage. Comparing to optical fiber based sensor systems, the coaxial cable sensors have the advantage of large strain and robustness, making this system suitable for structure health monitoring applications.

  8. Performances Study of Interferometric Radar Altimeters: from the Instrument to the Global Mission Definition

    Directory of Open Access Journals (Sweden)

    Anny Cazenave

    2006-03-01

    Full Text Available The main limitations of standard nadir-looking radar altimeters have been knownfor long. They include the lack of coverage (intertrack distance of typically 150 km for theT/P / Jason tandem, and the spatial resolution (typically 2 km for T/P and Jason, expectedto be a limiting factor for the determination of mesoscale phenomena in deep ocean. In thiscontext, various solutions using off-nadir radar interferometry have been proposed byRodriguez and al to give an answer to oceanographic mission objectives. This paperaddresses the performances study of this new generation of instruments, and dedicatedmission. A first approach is based on the Wide-Swath Ocean Altimeter (WSOA intended tobe implemented onboard Jason-2 in 2004 but now abandoned. Every error domain has beenchecked: the physics of the measurement, its geometry, the impact of the platform andexternal errors like the tropospheric and ionospheric delays. We have especially shown thestrong need to move to a sun-synchronous orbit and the non-negligible impact of propagation media errors in the swath, reaching a few centimetres in the worst case. Some changes in the parameters of the instrument have also been discussed to improve the overall error budget. The outcomes have led to the definition and the optimization of such an instrument and its dedicated mission.

  9. Wideband and high-power light sources for in-line interferometric diagnostics of laser structuring systems

    Science.gov (United States)

    Peterka, Pavel; Todorov, Filip; KašÎ¯k, Ivan; Matějec, Vlastimil; Podrazký, Ondřej; Šašek, Ladislav; Mallmann, Guilherme; Schmitt, Robert

    2012-01-01

    Laser structuring is rapidly developing manufacturing technique for broad spectrum of industrial branches, e.g. aerospace, power engineering, tool- and mould making, and automotive. It enables to prepare work pieces and products with very fine micro structures achieving a far better degree of details than conventional structuring techniques like etching or eroding. However, the state of art in laser structuring shows a crucial deficit. Used systems contain no metrology setup to detect the shape geometry (depth and length) and contour accuracy during the process. Therefore, an innovative in-line metrology technique based on low coherence interferometry for laser structuring systems has been investigated and described in the paper. In this contribution we present our results in the research of wideband and highpower light sources for the proposed low-coherence interferometric measurement system. The system can be incorporated into a structuring workplace equipped with a Q-switched ytterbium-doped fiber laser at 1064 nm for material processing. In the paper we focus on two wideband sources for such a measurement system. The first source is based on a superluminescent diode and the second one is based on an amplified spontaneous emission in a double-clad ytterbium-doped fiber. An example of results measured with the proposed in-line metrology system is presented.

  10. Saturn's rings - Particle composition and size distribution as constrained by observations at microwave wavelengths. II - Radio interferometric observations

    Science.gov (United States)

    Cuzzi, J. N.; Pollack, J. B.; Summers, A. L.

    1980-01-01

    Theoretical models are presented of the brightness of Saturn's rings at microwave wavelengths (0.34-21.0 cm) including both intrinsic ring emission and diffuse scattering by the rings of the planetary emission. In addition, several previously existing sets of interferometric observations of the Saturn system at 0.83, 3.71, 6.0, 11.1, and 21.0 cm wavelengths are analyzed. A comparison of models and experimental data make it possible to establish improved constraints on the properties of the rings. In particular, it is found that (1) the maximum optical depths in the rings is 1.5 + or - 0.3 referred to visible wavelengths; (2) a significant decrease in ring optical depths from 3.7 to 21.0 cm makes it possible to rule out the possibility that more than 30% of the cross section of the rings is composed of particles larger than about a meter; and (3) the ring particles cannot be primarily of silicate composition (independently of particle size), and the particles cannot be primarily smaller than about 0.1 cm, independently of composition.

  11. Investigating ground deformation and subsidence in northern Metro Manila, Philippines using Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR)

    Science.gov (United States)

    Eco, R. C.; Lagmay, A. A.; Bato, M. P.

    2011-12-01

    The extent of ground deformation and subsidence in northern Metro Manila was examined using Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) technique. Using the Stanford Method for Persistent Scatterers/Multi-Temporal InSAR (StaMPS/MTI) software, we processed 21 descending ENVISAT radar imageries taken from 2003 to 2006. The processed interferograms show high coherence due to the high density of PS points in the region of interest. The PSInSAR processing reveals several areas in northern Metro Manila, specifically in Caloocan, Malabon, Navotas and Valenzuela-collectively known as CAMANAVA-that exhibit deformation characteristics similar to that of ground subsidence. Results show that the areas manifesting apparent subsidence are moving with a maximum rate of 4.38 cm/year relative to the satellite. This is consistent with the geodetic surveying results from 1979 to 2009 showing subsidence of approximately 1 meter or 3.33 cm/year per year. Government data also identify these areas as among those with the highest rates of groundwater extraction in Metro Manila, suggesting the possibility of anthropogenic activities as the major cause of subsidence. With this study, we hope to get a better understanding of the nature of subsidence affecting parts of northern Metro Manila. Doing so would help mitigate the effects of potential flood disasters.

  12. Big data managing in a landslide early warning system: experience from a ground-based interferometric radar application

    Science.gov (United States)

    Intrieri, Emanuele; Bardi, Federica; Fanti, Riccardo; Gigli, Giovanni; Fidolini, Francesco; Casagli, Nicola; Costanzo, Sandra; Raffo, Antonio; Di Massa, Giuseppe; Capparelli, Giovanna; Versace, Pasquale

    2017-10-01

    A big challenge in terms or landslide risk mitigation is represented by increasing the resiliency of society exposed to the risk. Among the possible strategies with which to reach this goal, there is the implementation of early warning systems. This paper describes a procedure to improve early warning activities in areas affected by high landslide risk, such as those classified as critical infrastructures for their central role in society. This research is part of the project LEWIS (Landslides Early Warning Integrated System): An Integrated System for Landslide Monitoring, Early Warning and Risk Mitigation along Lifelines. LEWIS is composed of a susceptibility assessment methodology providing information for single points and areal monitoring systems, a data transmission network and a data collecting and processing center (DCPC), where readings from all monitoring systems and mathematical models converge and which sets the basis for warning and intervention activities. The aim of this paper is to show how logistic issues linked to advanced monitoring techniques, such as big data transfer and storing, can be dealt with compatibly with an early warning system. Therefore, we focus on the interaction between an areal monitoring tool (a ground-based interferometric radar) and the DCPC. By converting complex data into ASCII strings and through appropriate data cropping and average, and by implementing an algorithm for line-of-sight correction, we managed to reduce the data daily output without compromising the capability for performing.

  13. BINERY PSEUDO-RANDOM GRATING AS A STANDARD TEST SURFACE FOR MEASUREMENT OF MODULATION TRANSFER FUNCTION OF INTERFEROMETRIC MICROSCOPES.

    Energy Technology Data Exchange (ETDEWEB)

    YASHCHUK,V.V.; MCKINNEY, W.R.; TAKACS, P.Z.

    2007-08-01

    The task of designing high performance X-ray optical systems requires the development of sophisticated X-ray scattering calculations based on rigorous information about the optics. One of the most insightful approaches to these calculations is based on the power spectral density (PSD) distribution of the surface height. The major problem of measurement of a PSD distribution with an interferometric and/or atomic force microscope arises due to the unknown Modulation Transfer Function (MTF) of the instruments. The MTF characterizes the perturbation of the PSD distribution at higher spatial frequencies. Here, we describe a new method and dedicated test surfaces for calibration of the MTF of a microscope. The method is based on use of a specially designed Binary Pseudo-random (BPR) grating. Comparison of a theoretically calculated PSD spectrum of a BPR grating with a spectrum measured with the grating provides the desired calibration of the instrumental MTF. The theoretical background of the method, as well as results of experimental investigations are presented.

  14. Real-time interferometric monitoring and measuring of photopolymerization based stereolithographic additive manufacturing process: sensor model and algorithm

    Science.gov (United States)

    Zhao, X.; Rosen, D. W.

    2017-01-01

    As additive manufacturing is poised for growth and innovations, it faces barriers of lack of in-process metrology and control to advance into wider industry applications. The exposure controlled projection lithography (ECPL) is a layerless mask-projection stereolithographic additive manufacturing process, in which parts are fabricated from photopolymers on a stationary transparent substrate. To improve the process accuracy with closed-loop control for ECPL, this paper develops an interferometric curing monitoring and measuring (ICM&M) method which addresses the sensor modeling and algorithms issues. A physical sensor model for ICM&M is derived based on interference optics utilizing the concept of instantaneous frequency. The associated calibration procedure is outlined for ICM&M measurement accuracy. To solve the sensor model, particularly in real time, an online evolutionary parameter estimation algorithm is developed adopting moving horizon exponentially weighted Fourier curve fitting and numerical integration. As a preliminary validation, simulated real-time measurement by offline analysis of a video of interferograms acquired in the ECPL process is presented. The agreement between the cured height estimated by ICM&M and that measured by microscope indicates that the measurement principle is promising as real-time metrology for global measurement and control of the ECPL process.

  15. Comparison of PALSAR-2 Interferometric Estimates of Snow Water Equivalent, Airborne Snow Observatory Snow Depths, and Results from a Distributed Energy Balance Snow Model (iSnobal)

    Science.gov (United States)

    Deeb, E. J.; Marshall, H. P.; Painter, T. H.; Marks, D. G.; Hedrick, A. R.; Havens, S.; Forster, R. R.; Siqueira, P.

    2016-12-01

    The interferometric approach to estimating snow water equivalent (SWE) leverages the fact that at relatively low frequencies ( 1 GHz, L-Band), differences in snow microstructure and layering do not significantly affect the radar backscatter of dry snow. At these frequencies, the main contribution of the radar backscatter is the snow/ground interface, and the difference in the timing of the radar propagation through the snowpack is controlled by snow depth, density and liquid water content. While engineering limitations prevent direct measurement of absolute radar travel-time, interferometric phase shift between acquisitions can be used to monitor changes in radar travel-time, caused by changes in snow properties. PALSAR-2 is a L-Band synthetic aperture radar (SAR) aboard the Japan Aerospace Exploration Agency's (JAXA) ALOS-2 satellite. Launched in 2014, PALSAR-2 interferometric pairs geographically and temporally overlap data collected by the NASA/JPL Airborne Snow Observatory (ASO) which provides spatial distribution of snow depths across basins (e.g. Tuolumne, CA and Grand Mesa, CO) identified as contributing significantly to NASA's multi-year airborne SnowEx campaign. As part of ASO's operational requirements, a spatially distributed energy balance snow model (iSnobal) is run over these domains estimating density (and other snow properties) and providing SWE products for water resource managers as well as other cryospheric science applications. This effort identifies PALSAR-2 satellite pairs closely coincident with ASO collections, processes interferometric products of coherence and phase change, and compares these results with the spatially distributed snow depths from ASO and modeled snow densities from iSnobal. Moreover, for satellite acquisitions not temporally matching the ASO collections, the modeled snow properties (depths and densities) from iSnobal are used for comparison with interferometric estimates of SWE. The integration of ground measurements

  16. Super-resolution

    DEFF Research Database (Denmark)

    Nasrollahi, Kamal; Moeslund, Thomas B.

    2014-01-01

    and aerial imaging to medical image processing, to facial image analysis, text image analysis, sign and number plates reading, and biometrics recognition, to name a few. This has resulted in many research papers, each developing a new super-resolution algorithm for a specific purpose. The current...... comprehensive survey provides an overview of most of these published works by grouping them in a broad taxonomy. For each of the groups in the taxonomy, the basic concepts of the algorithms are first explained and then the paths through which each of these groups have evolved are given in detail, by mentioning...... the contributions of different authors to the basic concepts of each group. Furthermore, common issues in super-resolution algorithms, such as imaging models and registration algorithms, optimization of the cost functions employed, dealing with color information, improvement factors, assessment of super...

  17. ALTERNATIVE DISPUTE RESOLUTION

    Directory of Open Access Journals (Sweden)

    Mihaela Irina IONESCU

    2016-05-01

    Full Text Available Alternative dispute resolution (ADR includes dispute resolution processes and techniques that act as a means for disagreeing parties to come to an agreement short of litigation. It is a collective term for the ways that parties can settle disputes, with (or without the help of a third party. Despite historic resistance to ADR by many popular parties and their advocates, ADR has gained widespread acceptance among both the general public and the legal profession in recent years. In fact, some courts now require some parties to resort to ADR of some type, before permitting the parties' cases to be tried. The rising popularity of ADR can be explained by the increasing caseload of traditional courts, the perception that ADR imposes fewer costs than litigation, a preference for confidentiality, and the desire of some parties to have greater control over the selection of the individual or individuals who will decide their dispute. Directive 2013/11/EU of the European Parliament and of the Council on alternative dispute resolution for consumer disputes and amending Regulation (EC No 2006/2004 and Directive 2009/22/EC (hereinafter „Directive 2013/11/EU” aims to ensure a high level of consumer protection and the proper functioning of the internal market by ensuring that complaints against traders can be submitted by consumers on a voluntary basis, to entities of alternative disputes which are independent, impartial, transparent, effective, simple,quick and fair. Directive 2013/11/EU establishes harmonized quality requirements for entities applying alternative dispute resolution procedure (hereinafter "ADR entity" to provide the same protection and the same rights of consumers in all Member States. Besides this, the present study is trying to present broadly how are all this trasposed in the romanian legislation.

  18. Interferometric view of the circumstellar envelopes of northern FU Orionis-type stars

    Science.gov (United States)

    Fehér, O.; Kóspál, Á.; Ábrahám, P.; Hogerheijde, M. R.; Brinch, C.

    2017-11-01

    Context. FU Orionis-type objects are pre-main sequence, low-mass stars with large outbursts in visible light that last for several years or decades. They are thought to represent an evolutionary phase during the life of every young star when accretion from the circumstellar disk is enhanced during recurring time periods. These outbursts are able to rapidly build up the star while affecting the physical conditions inside the circumstellar disk and thus the ongoing or future planet formation. In many models, infall from a circumstellar envelope seems to be necessary to trigger the outbursts. Aims: We characterise the morphology and the physical parameters of the circumstellar material around FU Orionis-type stars using the emission of millimetre-wavelength molecular tracers. The high-spatial-resolution study provides insight into the evolutionary state of the objects, the distribution of parameters in the envelopes and the physical processes forming the environment of these stars. Methods: We observed the J = 1-0 rotational transition of 13CO and C18O towards eight northern FU Orionis-type stars (V1057 Cyg, V1515 Cyg, V2492 Cyg, V2493 Cyg, V1735 Cyg, V733 Cep, RNO 1B and RNO 1C) and determine the spatial and velocity structure of the circumstellar gas on a scale of a few thousand AU. We derive temperatures and envelope masses and discuss the kinematics of the circumstellar material. Results: We detected extended CO emission associated with all our targets. Smaller-scale CO clumps were found to be associated with five objects with radii of 2000-5000 AU and masses of 0.02-0.5 M⊙; these are clearly heated by the central stars. Three of these envelopes are also strongly detected in the 2.7 mm continuum. No central CO clumps were detected around V733 Cep and V710 Cas which can be interpreted as envelopes but there are many other clumps in their environments. Traces of outflow activity were observed towards V1735 Cyg, V733 Cep and V710 Cas. Conclusions: The diversity of

  19. Retrieving mesospheric winds and gravity waves using high resolution radar measurements of polar mesospheric summer echoes with MAARSY

    Science.gov (United States)

    Stober, G.; Sommer, S.; Schult, C.; Chau, J. L.; Latteck, R.

    2013-12-01

    The Middle Atmosphere Alomar Radar System (MAARSY) located at the northern Norwegian island of Andøya (69.3 ° N, 16° E) observes polar mesosphere summer echoes (PMSE) on a regular basis. This backscatter turned out to be an ideal tracer of atmospheric dynamics and to investigate the wind field at the mesosphere/lower thermosphere (MLT) at high spatial and temporal scales. MAARSY is dedicated to explore the polar mesosphere at such high resolution and employs an active phased array antenna with the capability to steer the beam on a pulse-to-pulse basis, which permits to perform systematic scanning of PMSE and to investigate the horizontal structure of the backscatter. The radar also uses a 16 channel receiver system for interferometric applications e.g. mean angle of arrival analysis or coherent radar imaging. Here we present measurements using these features of MAARSY to study the wind field at the MLT applying sophisticated wind analysis algorithms such as velocity azimuth display or volume velocity processing to derive gravity wave parameters such as horizontal wave length, phase speed and propagation direction. Further, we compare the interferometrically corrected and uncorrected wind measurements to emphasize the importance to account for likely edge effects using PMSE as tracer of the dynamics. The observations indicate huge deviations from the nominal beam pointing direction at the upper and lower edges of the PMSE altering the wind analysis.

  20. Ground Deformation Monitoring of Nisyros Volcano (SE Greece) based on Space Geodesy and SqueeSAR Interferometric Technique

    Science.gov (United States)

    Sakkas, Vassilis; Novali, Fabrizio; Ferretti, Alessandro; Lagios, Evangelos

    2017-04-01

    The Hellenic Volcanic Arc (HVA) is regarded as a magmatic expression of the still-active north-eastward-directed subduction of the African Plate beneath the Aegean micro-plate. The south-eastern part of the HVA, including Kos, Yali and Nisyros islands, is geodynamically very active that exhibited an "unrest" period during 1996-2000. At that period Nisyros volcanic field showed a significant ground deformation and a temperature increase of the fumaroles, during and after an intense seismic activity that broke out in the area between 1996 and 1998. A dense GPS network was installed in the island in 1997 that was expanded to the neighbouring islets of Yali and Strongyli to monitor the ground deformation. Differential Interferometry was also applied to determine the ground deformation prior to 1997. The study revealed "opening" of the island along the main faulting zones and intense uplift (>90 mm) during 1997-1999 that was gradually reduced the following years. The observed deformation was modelled using two expanding Mogi point sources, being correlated to magmatic chambers on- and off-shore of Nisyros, their location of which was also supported from geophysical and neotectonic data. Continuation of the GPS measurements up to 2016, in combination with continuous GPS data from the broader area and advanced interferometric data analysis, provided a detailed spatial and temporal ground deformation monitoring of Nisyros-Yali volcanic field after the period of the volcanic crisis. The continuous (since 2012) GPS data from the neighbouring islands of Kalymnos, Tilos and Rhodes revealed regional velocity vectors slightly different from the ones observed in Nisyros-Kos, especially in the vertical component. The GPS campaign results from 2000 to 2016 showed intense subsidence (-5 to -10 mm/yr) in the northern and southern parts of Nisyros, and even higher rates in the central part (up to -20 mm/yr). That caused the western, the eastern and the southern flanks of the caldera

  1. HIGH RESOLUTION DEFORMATION TIME SERIES ESTIMATION FOR DISTRIBUTED SCATTERERS USING TERRASAR-X DATA

    Directory of Open Access Journals (Sweden)

    K. Goel

    2012-07-01

    Full Text Available In recent years, several SAR satellites such as TerraSAR-X, COSMO-SkyMed and Radarsat-2 have been launched. These satellites provide high resolution data suitable for sophisticated interferometric applications. With shorter repeat cycles, smaller orbital tubes and higher bandwidth of the satellites; deformation time series analysis of distributed scatterers (DSs is now supported by a practical data basis. Techniques for exploiting DSs in non-urban (rural areas include the Small Baseline Subset Algorithm (SBAS. However, it involves spatial phase unwrapping, and phase unwrapping errors are typically encountered in rural areas and are difficult to detect. In addition, the SBAS technique involves a rectangular multilooking of the differential interferograms to reduce phase noise, resulting in a loss of resolution and superposition of different objects on ground. In this paper, we introduce a new approach for deformation monitoring with a focus on DSs, wherein, there is no need to unwrap the differential interferograms and the deformation is mapped at object resolution. It is based on a robust object adaptive parameter estimation using single look differential interferograms, where, the local tilts of deformation velocity and local slopes of residual DEM in range and azimuth directions are estimated. We present here the technical details and a processing example of this newly developed algorithm.

  2. Lens-free spectral light-field fusion microscopy for contrast- and resolution-enhanced imaging of biological specimens

    Science.gov (United States)

    Kazemzadeh, Farnoud; Jin, Chao; Molladavoodi, Sara; Mei, Yu; Emelko, Monica B.; Gorbet, Maud B.; Wong, Alexander

    2015-08-01

    A lensfree spectral light-field fusion microscopy (LSLFM) system is presented for enabling contrast- and resolution-enhanced imaging of biological specimens. LSLFM consists of a pulsed multispectral lensfree microscope for capturing interferometric light-field encodings at various wavelengths, and Bayesian-based fusion to reconstruct a fused object light-field from the encodings. By fusing unique object detail information captured at different wavelengths, LSLFM can achieve improved resolution, contrast, and signal-to-noise ratio (SNR) over a single-channel lensfree microscopy system. A five-channel LSLFM system was developed and quantitatively evaluated to validate the design. Experimental results demonstrated that the LSLFM system provided SNR improvements of 6-12 dB, as well as a six-fold improvement in the dispersion index (DI), over that achieved using a single-channel, resolution-enhancing lensfree deconvolution microscopy system or its multi-wavelength counterpart. Furthermore, the LSLFM system achieved an increase in numerical aperture (NA) of ~16% over a single-channel resolution-enhancing lensfree deconvolution microscopy system at the highest-resolution wavelength used in the study. Samples of Staurastrum paradoxum, a waterborne algae, and human corneal epithelial cells were imaged using the system to illustrate its potential for enhanced imaging of biological specimens.

  3. Fundamental study of microelectronic chip response under laser ultrasonic-interferometric inspection using C-scan method

    Science.gov (United States)

    Yang, Lei; Gong, Jie; Ume, I. Charles

    2014-02-01

    In modern surface mount packaging technologies, such as flip chips, chip scale packages, and ball grid arrays(BGA), chips are attached to the substrates/printed wiring board (PWB) using solder bump interconnections. The quality of solder bumps between the chips and the substrate/board is difficult to inspect. Laser ultrasonic-interferometric technique was proved to be a promising approach for solder bump inspection because of its noncontact and nondestructive characteristics. Different indicators extracted from received signals have been used to predict the potential defects, such as correlation coefficient, error ratio, frequency shifting, etc. However, the fundamental understanding of the chip behavior under laser ultrasonic inspection is still missing. Specifically, it is not sure whether the laser interferometer detected out-of-plane displacements were due to wave propagation or structural vibration when the chip was excited by pulsed laser. Plus, it is found that the received signals are chip dependent. Both challenges impede the interpretation of acquired signals. In this paper, a C-scan method was proposed to study the underlying phenomenon during laser ultrasonic inspection. The full chip was inspected. The response of the chip under laser excitation was visualized in a movie resulted from acquired signals. Specifically, a BGA chip was investigated to demonstrate the effectiveness of this method. By characterizing signals using discrete wavelet transform(DWT), both ultrasonic wave propagation and vibration were observed. Separation of them was successfully achieved using ideal band-pass filter and visualized in resultant movies, too. The observed ultrasonic waves were characterized and their respective speeds were measured by applying 2-D FFT. The C-scan method, combined with different digital signal processing techniques, was proved to be an very effective methodology to learn the behavior of chips under laser excitation. This general procedure can be

  4. FIRST-LIGHT LBT NULLING INTERFEROMETRIC OBSERVATIONS: WARM EXOZODIACAL DUST RESOLVED WITHIN A FEW AU OF η Crv

    Energy Technology Data Exchange (ETDEWEB)

    Defrère, D.; Hinz, P. M.; Skemer, A. J.; Bailey, V. P.; Hoffmann, W. F.; Arbo, P.; Brusa, G.; Downey, E. C.; Durney, O.; Gaspar, A.; Grenz, P. [Steward Observatory, Department of Astronomy, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Kennedy, G. M. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Mennesson, B.; Bryden, G. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States); Millan-Gabet, R.; Beichman, C. [NASA Exoplanet Science Institute, California Institute of Technology, 770 South Wilson Avenue, Pasadena, CA 91125 (United States); Danchi, W. C. [NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory, Code 667, Greenbelt, MD 20771 (United States); Absil, O. [Département d' Astrophysique, Géophysique et Océanographie, Université de Liège, 17 Allée du Six Août, B-4000 Sart Tilman (Belgium); Esposito, S. [INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, I-50125 Firenze (Italy); Haniff, C., E-mail: ddefrere@email.arizona.edu [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); and others

    2015-01-20

    We report on the first nulling interferometric observations with the Large Binocular Telescope Interferometer (LBTI), resolving the N' band (9.81-12.41 μm) emission around the nearby main-sequence star η Crv (F2V, 1-2 Gyr). The measured source null depth amounts to 4.40% ± 0.35% over a field-of-view of 140 mas in radius (∼2.6 AU for the distance of η Crv) and shows no significant variation over 35° of sky rotation. This relatively low null is unexpected given the total disk to star flux ratio measured by the Spitzer Infrared Spectrograph (IRS; ∼23% across the N' band), suggesting that a significant fraction of the dust lies within the central nulled response of the LBTI (79 mas or 1.4 AU). Modeling of the warm disk shows that it cannot resemble a scaled version of the solar zodiacal cloud unless it is almost perpendicular to the outer disk imaged by Herschel. It is more likely that the inner and outer disks are coplanar and the warm dust is located at a distance of 0.5-1.0 AU, significantly closer than previously predicted by models of the IRS spectrum (∼3 AU). The predicted disk sizes can be reconciled if the warm disk is not centrosymmetric, or if the dust particles are dominated by very small grains. Both possibilities hint that a recent collision has produced much of the dust. Finally, we discuss the implications for the presence of dust for the distance where the insolation is the same as Earth's (2.3 AU)

  5. Interferometric investigations with the S1 constellation: an application to the Vesuvius/Campi Flegrei volcanic test site

    Science.gov (United States)

    Borgstrom, Sven; Del Gaudio, Carlo; De Martino, Prospero; Siniscalchi, Valeria; Prats-Iraola, Pau; Nannini, Matteo; Yague-Martinez, Nestor; Pinheiro, Muriel; Kim, Jun-Su; Vecchioli, Francesco; Minati, Federico; Costantini, Mario; Foumelis, Michael; Desnos, Yves-Louis

    2017-04-01

    The contribution focuses on the current status of the ESA study entitled "INSARAP Sentinel-1 Constellation Study" and investigates the interferometric performance of the S1A/S1B units. In particular, we refer to the Vesuvius/Campi Flegrei (Southern Italy) volcanic test site, where the continuous inflation (about 35 cm from 2011 to date) and the huge availability of ground-based geodetic data (continuous GPS - cGPS - leveling, tiltmetric, gravimetric, etc.) from the INGV-Osservatorio Vesuviano monitoring networks have allowed to get a clear deformation signal, besides the comparison between S1A/S1B and geodetic data. In this regard, the integration between InSAR and geodetic measurements is crucial for a continuous and extended monitoring of such an active volcanic area, as InSAR investigations allow to get an information on wide areas, whereas permanent networks (e.g., cGPS), allow to provide a continuous information complementing InSAR, which is limited by its revisiting time. Comparisons between S1 constellation data and geodetic measurements, with a particular focus on cGPS, will be presented, exploiting both LOS and inverted (E-W and vertical inversion) InSAR data starting from October, 2014. In addition, as a next step we are planning to model the deformation source of the area by exploiting the S1 time series results. Ultimately, very encouraging results suggest for a continuation of this activity also for the future, showing the great potential of S1 constellation data for monitoring active volcanic areas and, in general, to retrieve a very high quality deformation signal.

  6. Interferometric acquisition and fire control radar for short-range missile defense with optimized radar distribution (SWORD)

    Science.gov (United States)

    Smith, Ronald A.; Shipman, Mark; Holder, E. J.; Williams, James K.

    2002-07-01

    The United States Army Space and Missile Defense Command (USASMDC) has interest in a technology demonstration that capitalizes on investment in fire control and smart interceptor technologies that have matured beyond basic research. The concept "SWORD" (Short range missile defense With Optimized Radar Distribution) consists of a novel approach utilizing a missile interceptor and interferometric fire control radar. A hit-to-kill, closed-loop, command guidance scheme is planned that takes advantage of extremely accurate target and interceptor state vectors derived via the fire control radar. The fire control system has the capability to detect, track, and classify multiple threats in a tactical regime as well as simultaneously provide command guidance updates to multiple missile interceptors. The missile interceptor offers a cost reduction potential as well as an enhancement to the kinematics range and lethality over existing SHORAD systems. Additionally, the Radio Frequency (RF) guidance scheme offers increased battlefield weather performance. The Air Defense (AD) community, responding to current threat capabilities and trends, has identified an urgent need to have a capability to counter proliferated, low cost threats with a low cost-per-kill weapon system. The SWORD system will offer a solution that meets this need. The SWORD critical technologies will be identified including a detailed description of each. Validated test results and basic principles of operation will be presented to prove the merit of the past investments. The Deptuy Assistant Secretary of the Army for Research and Technology [DAS(R&T)] has a three-year Science and Technology Program to evaluate the errors and proposed mitigation techniques associated with target spectral dispersion and range gate straddle. Preliminary Bench-Top Experiment results will be presented in this paper.

  7. Resolution Enhancement of Multilook Imagery

    Energy Technology Data Exchange (ETDEWEB)

    Galbraith, Amy E. [Univ. of Arizona, Tucson, AZ (United States)

    2004-07-01

    This dissertation studies the feasibility of enhancing the spatial resolution of multi-look remotely-sensed imagery using an iterative resolution enhancement algorithm known as Projection Onto Convex Sets (POCS). A multi-angle satellite image modeling tool is implemented, and simulated multi-look imagery is formed to test the resolution enhancement algorithm. Experiments are done to determine the optimal con guration and number of multi-angle low-resolution images needed for a quantitative improvement in the spatial resolution of the high-resolution estimate. The important topic of aliasing is examined in the context of the POCS resolution enhancement algorithm performance. In addition, the extension of the method to multispectral sensor images is discussed and an example is shown using multispectral confocal fluorescence imaging microscope data. Finally, the remote sensing issues of atmospheric path radiance and directional reflectance variations are explored to determine their effect on the resolution enhancement performance.

  8. Failure Diameter Resolution Study

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-12-19

    Previously the SURFplus reactive burn model was calibrated for the TATB based explosive PBX 9502. The calibration was based on fitting Pop plot data, the failure diameter and the limiting detonation speed, and curvature effect data for small curvature. The model failure diameter is determined utilizing 2-D simulations of an unconfined rate stick to find the minimum diameter for which a detonation wave propagates. Here we examine the effect of mesh resolution on an unconfined rate stick with a diameter (10mm) slightly greater than the measured failure diameter (8 to 9 mm).

  9. LHCb VELO tracking resolutions

    Science.gov (United States)

    Alexander, M. T.; LHCb VELO Group

    2013-01-01

    The LHCb detector at the Large Hadron Collider (LHC) at CERN is designed to make precision measurements of mesons and baryons containing b and c quarks. Many analyses performed using data from LHCb examine properties of particles and anti-particles as a function of proper decay time. Precise measurements of production and decay vertices are thus essential. The Vertex Locator (VELO) subdetector of LHCb performs this task. The excellent performance of the VELO with respect to the resolutions it achieves on single hits, impact parameters, and primary vertex positions is presented, with particular attention paid to measurement of impact parameters.

  10. High resolution imaging of massive young stellar objects and a sample of molecular outflow sources

    Science.gov (United States)

    Maud, Luke Thomas

    2013-09-01

    This thesis contains a study of millimetre wavelength observations of massive young stellar objects (MYSOs) both via interferometric and single dish observations. First, the high angular resolution observations ( up to ∼0.1") from a variety of interferometers of the MYSO, S140 IRS1, are presented. This source is one of only two prototypes that have ionised equatorial emission from a radiatively driven disc wind. The observations confirm that IRS1 has a dusty disc at a position angle compatible with that of the disc wind emission, and confirms the disc wind nature for the first time. Secondly, the observations of S140 IRS1 are modelled using a 2D axisymmetric radiative transfer code. Extensive models producing synthetic data at millimetre wavelengths were developed. These models show that on the largest scales, typically accessible with single dish observations or compact interferometric configurations, the spectral energy distribution is relatively unchanged by the addition of a compact dust disc. However, a disc is required to match the interferometric visibilities at the smaller scales. The position angle of the disc is well constrained via a newly developed 2D visibility fitting method. The models however, are degenerate and there are a range of realistic best fitting discs. The third section presents the single dish observations of the core material traced by C18O around 99 MYSOs and compact HII regions from the RMS survey. A method to calculate the core masses and velocity extent is reported. The method is accurate and robust, and can be applied to any molecular line emission. An updated distance limited sample contains 87 sources and is complete to 1000 L⊙. It is a representative sample of MYSOs and HII regions. All of the cores harbour at least one massive protostar. Finally, methodologies to establish outflow parameters via 12CO (3-2) and 13CO (3-2) data are investigated. Multiple techniques are trialed for a well studied test! source, IRAS 20126

  11. Resolution of praziquantel.

    Directory of Open Access Journals (Sweden)

    Michael Woelfle

    2011-09-01

    Full Text Available BACKGROUND: Praziquantel remains the drug of choice for the worldwide treatment and control of schistosomiasis. The drug is synthesized and administered as a racemate. Use of the pure active enantiomer would be desirable since the inactive enantiomer is associated with side effects and is responsible for the extremely bitter taste of the pill. METHODOLOGY/PRINCIPAL FINDINGS: We have identified two resolution approaches toward the production of praziquantel as a single enantiomer. One approach starts with commercially available praziquantel and involves a hydrolysis to an intermediate amine, which is resolved with a derivative of tartaric acid. This method was discovered through an open collaboration on the internet. The second method, identified by a contract research organisation, employs a different intermediate that may be resolved with tartaric acid itself. CONCLUSIONS/SIGNIFICANCE: Both resolution procedures identified show promise for the large-scale, economically viable production of praziquantel as a single enantiomer for a low price. Additionally, they may be employed by laboratories for the production of smaller amounts of enantiopure drug for research purposes that should be useful in, for example, elucidation of the drug's mechanism of action.

  12. Interferometric measurements of dry mass content in nuclei and cytoplasm in the life cycle of antheridial filaments cells of Chara vulgaris L. in their successive developmental stages

    Directory of Open Access Journals (Sweden)

    Hanna Kuran

    2015-01-01

    Full Text Available Interferometric measurements of the nucleus and cytoplasm dry mass during interphase in the successive stages of development of antheridial filaments of Chara vulgaris demonstrated that the dry mass and surface area of cell nuclei double in size in each of the successive generations of the filaments, whereas neither the surface nor the dry mass of the cytoplasm increase in such proportion in the same period. In the successive stages of development of the antheridial filaments the dry mass and surface area of the nuclei and cytoplasm gradually diminish.

  13. Civil Engineering Dispute Resolution

    CERN Document Server

    Osborne, J

    2001-01-01

    Construction work on the civil engineering contract started at Point 5 in August 1998. The new surface buildings and underground structures are necessary to accommodate the CMS detector for the LHC Project. The principal underground works consist of two new shafts, two parallel caverns separated by a supporting pillar, and a number of small connection tunnels and service galleries. A dispute resolution procedure has been included in the contract, whereby a Panel of Adjudicators may be called upon to make a decision in the case of a difference or dispute between the parties. The aim of this paper is to present CERN's first experience of civil engineering Adjudication arising from problems encountered with the ground freezing technique employed to allow construction of two new shafts.

  14. High Time Resolution Astrophysics

    CERN Document Server

    Phelan, Don; Shearer, Andrew

    2008-01-01

    High Time Resolution Astrophysics (HTRA) is an important new window to the universe and a vital tool in understanding a range of phenomena from diverse objects and radiative processes. This importance is demonstrated in this volume with the description of a number of topics in astrophysics, including quantum optics, cataclysmic variables, pulsars, X-ray binaries and stellar pulsations to name a few. Underlining this science foundation, technological developments in both instrumentation and detectors are described. These instruments and detectors combined cover a wide range of timescales and can measure fluxes, spectra and polarisation. These advances make it possible for HTRA to make a big contribution to our understanding of the Universe in the next decade.

  15. Lexical ambiguity resolution

    Energy Technology Data Exchange (ETDEWEB)

    Small, S.; Cottrell, G.; Tanenhaus, M.

    1987-01-01

    This book collects much of the best research currently available on the problem of lexical ambiguity resolution in the processing of human language. When taken out of context, sentences are usually ambiguous. When actually uttered in a dialogue or written in text, these same sentences often have unique interpretations. The inherent ambiguity of isolated sentences, becomes obvious in the attempt to write a computer program to understand them. Different views have emerged on the nature of context and the mechanisms by which it directs unambiguous understanding of words and sentences. These perspectives are represented and discussed. Eighteen original papers from a valuable source book for cognitive scientists in AI, psycholinguistics, neuropsychology, or theoretical linguistics.

  16. Set-up of a high-resolution 300 mK atomic force microscope in an ultra-high vacuum compatible 3He/10 T cryostat

    Science.gov (United States)

    von Allwörden, H.; Ruschmeier, K.; Köhler, A.; Eelbo, T.; Schwarz, A.; Wiesendanger, R.

    2016-07-01

    The design of an atomic force microscope with an all-fiber interferometric detection scheme capable of atomic resolution at about 500 mK is presented. The microscope body is connected to a small pumped 3He reservoir with a base temperature of about 300 mK. The bakeable insert with the cooling stage can be moved from its measurement position inside the bore of a superconducting 10 T magnet into an ultra-high vacuum chamber, where the tip and sample can be exchanged in situ. Moreover, single atoms or molecules can be evaporated onto a cold substrate located inside the microscope. Two side chambers are equipped with standard surface preparation and surface analysis tools. The performance of the microscope at low temperatures is demonstrated by resolving single Co atoms on Mn/W(110) and by showing atomic resolution on NaCl(001).

  17. Set-up of a high-resolution 300 mK atomic force microscope in an ultra-high vacuum compatible (3)He/10 T cryostat.

    Science.gov (United States)

    von Allwörden, H; Ruschmeier, K; Köhler, A; Eelbo, T; Schwarz, A; Wiesendanger, R

    2016-07-01

    The design of an atomic force microscope with an all-fiber interferometric detection scheme capable of atomic resolution at about 500 mK is presented. The microscope body is connected to a small pumped (3)He reservoir with a base temperature of about 300 mK. The bakeable insert with the cooling stage can be moved from its measurement position inside the bore of a superconducting 10 T magnet into an ultra-high vacuum chamber, where the tip and sample can be exchanged in situ. Moreover, single atoms or molecules can be evaporated onto a cold substrate located inside the microscope. Two side chambers are equipped with standard surface preparation and surface analysis tools. The performance of the microscope at low temperatures is demonstrated by resolving single Co atoms on Mn/W(110) and by showing atomic resolution on NaCl(001).

  18. A novel interferometric method for the study of the viscoelastic properties of ultra-thin polymer films determined from nanobubble inflation

    Science.gov (United States)

    Chapuis, P.; Montgomery, P. C.; Anstotz, F.; Leong-Hoï, A.; Gauthier, C.; Baschnagel, J.; Reiter, G.; McKenna, G. B.; Rubin, A.

    2017-09-01

    Glass formation and glassy behavior remain as the important areas of investigation in soft matter physics with many aspects which are still not completely understood, especially at the nanometer size-scale. In the present work, we show an extension of the "nanobubble inflation" method developed by O'Connell and McKenna [Rev. Sci. Instrum. 78, 013901 (2007)] which uses an interferometric method to measure the topography of a large array of 5 μ m sized nanometer thick films subjected to constant inflation pressures during which the bubbles grow or creep with time. The interferometric method offers the possibility of making measurements on multiple bubbles at once as well as having the advantage over the AFM methods of O'Connell and McKenna of being a true non-contact method. Here we demonstrate the method using ultra-thin films of both poly(vinyl acetate) (PVAc) and polystyrene (PS) and discuss the capabilities of the method relative to the AFM method, its advantages and disadvantages. Furthermore we show that the results from experiments on PVAc are consistent with the prior work on PVAc, while high stress results with PS show signs of a new non-linear response regime that may be related to the plasticity of the ultra-thin film.

  19. A novel interferometric method for the study of the viscoelastic properties of ultra-thin polymer films determined from nanobubble inflation.

    Science.gov (United States)

    Chapuis, P; Montgomery, P C; Anstotz, F; Leong-Hoï, A; Gauthier, C; Baschnagel, J; Reiter, G; McKenna, G B; Rubin, A

    2017-09-01

    Glass formation and glassy behavior remain as the important areas of investigation in soft matter physics with many aspects which are still not completely understood, especially at the nanometer size-scale. In the present work, we show an extension of the "nanobubble inflation" method developed by O'Connell and McKenna [Rev. Sci. Instrum. 78, 013901 (2007)] which uses an interferometric method to measure the topography of a large array of 5 μm sized nanometer thick films subjected to constant inflation pressures during which the bubbles grow or creep with time. The interferometric method offers the possibility of making measurements on multiple bubbles at once as well as having the advantage over the AFM methods of O'Connell and McKenna of being a true non-contact method. Here we demonstrate the method using ultra-thin films of both poly(vinyl acetate) (PVAc) and polystyrene (PS) and discuss the capabilities of the method relative to the AFM method, its advantages and disadvantages. Furthermore we show that the results from experiments on PVAc are consistent with the prior work on PVAc, while high stress results with PS show signs of a new non-linear response regime that may be related to the plasticity of the ultra-thin film.

  20. Interferometric visibility and coherence

    Science.gov (United States)

    Biswas, Tanmoy; García Díaz, María; Winter, Andreas

    2017-07-01

    Recently, the basic concept of quantum coherence (or superposition) has gained a lot of renewed attention, after Baumgratz et al. (Phys. Rev. Lett. 113, 140401. (doi:10.1103/PhysRevLett.113.140401)), following Åberg (http://arxiv.org/abs/quant-ph/0612146), have proposed a resource theoretic approach to quantify it. This has resulted in a large number of papers and preprints exploring various coherence monotones, and debating possible forms for the resource theory. Here, we take the view that the operational foundation of coherence in a state, be it quantum or otherwise wave mechanical, lies in the observation of interference effects. Our approach here is to consider an idealized multi-path interferometer, with a suitable detector, in such a way that the visibility of the interference pattern provides a quantitative expression of the amount of coherence in a given probe state. We present a general framework of deriving coherence measures from visibility, and demonstrate it by analysing several concrete visibility parameters, recovering some known coherence measures and obtaining some new ones.

  1. Interferometric shoreline mapping

    NARCIS (Netherlands)

    Koppen, C.G. van; Groot, J.S.; Vogelzang, J.; Dierikx-Platschorre, Y.

    2000-01-01

    Information on the location and evolution of shorelines is valuable. This information can be obtained from satellite Synthetic Aperture Radar (SAR) imagery. Direct, unsupervised classifications methods give poor results because of the high noise level in SAR images and the scattering properties of

  2. Optical fiber sensors-based temperature distribution measurement in ex vivo radiofrequency ablation with submillimeter resolution

    Science.gov (United States)

    Macchi, Edoardo Gino; Tosi, Daniele; Braschi, Giovanni; Gallati, Mario; Cigada, Alfredo; Busca, Giorgio; Lewis, Elfed

    2014-11-01

    Radiofrequency thermal ablation (RFTA) induces a high-temperature field in a biological tissue having steep spatial (up to 6°C/mm) and temporal (up to 1°C/s) gradients. Applied in cancer care, RFTA produces a localized heating, cytotoxic for tumor cells, and is able to treat tumors with sizes up to 3 to 5 cm in diameter. The online measurement of temperature distribution at the RFTA point of care has been previously carried out with miniature thermocouples and optical fiber sensors, which exhibit problems of size, alteration of RFTA pattern, hysteresis, and sensor density worse than 1 sensor/cm. In this work, we apply a distributed temperature sensor (DTS) with a submillimeter spatial resolution for the monitoring of RFTA in porcine liver tissue. The DTS demodulates the chaotic Rayleigh backscattering pattern with an interferometric setup to obtain the real-time temperature distribution. A measurement chamber has been set up with the fiber crossing the tissue along different diameters. Several experiments have been carried out measuring the space-time evolution of temperature during RFTA. The present work showcases the temperature monitoring in RFTA with an unprecedented spatial resolution and is exportable to in vivo measurement; the acquired data can be particularly useful for the validation of RFTA computational models.

  3. Tele-AAC Resolution.

    Science.gov (United States)

    Anderson, Kate; Boisvert, Michelle K; Doneski-Nicol, Janis; Gutmann, Michelle L; Hall, Nerissa C; Morelock, Cynthia; Steele, Richard; Cohn, Ellen R

    2012-01-01

    Approximately 1.3% of all people, or about 4 million Americans, cannot rely on their natural speech to meet their daily communication needs. Telepractice offers a potentially cost-effective service delivery mechanism to provide clinical AAC services at a distance to the benefit of underserved populations in the United States and worldwide. Tele-AAC is a unique cross-disciplinary clinical service delivery model that requires expertise in both telepractice and augmentative and alternative communication (AAC) systems. The Tele-AAC Working Group of the 2012 ISAAC Research Symposium therefore drafted a resolution underscoring the importance of identifying and characterizing the unique opportunities and constraints of Tele-AAC in all aspects of service delivery. These include, but are not limited to: needs assessments; implementation planning; device/system procurement, set-up and training; quality assurance, client progress monitoring, and follow-up service delivery. Tele-AAC, like other telepractice applications, requires adherence to the ASHA Code of Ethics and other policy documents, and state, federal, and international laws, as well as a competent technological infrastructure. The Working Group recommends that institutions of higher education and professional organizations provide training in Tele-AAC service provision. In addition, research and development are needed to create validity measures across Tele-AAC practices (i.e., assessment, implementation, and consultation); determine the communication competence levels achieved by Tele-AAC users; discern stakeholders' perceptions of Tele-AAC services (e.g., acceptability and viability); maximize Tele-AAC's capacity to engage multiple team members in AAC assessment and ongoing service; identify the limitations and barriers of Tele-AAC provision; and develop potential solutions.

  4. Tele-AAC Resolution

    Directory of Open Access Journals (Sweden)

    Kate Anderson

    2012-12-01

    Full Text Available Approximately 1.3% of all people, or about 4 million Americans, cannot rely on their natural speech to meet their daily communication needs. Telepractice offers a potentially cost-effective service delivery mechanism to provide clinical AAC services at a distance to the benefit of underserved populations in the United States and worldwide.  Tele-AAC is a unique cross-disciplinary clinical service delivery model that requires expertise in both telepractice and augmentative and alternative communication (AAC systems.  The Tele-AAC Working Group of the 2012 ISAAC Research Symposium therefore drafted a resolution underscoring the importance of identifying and characterizing the unique opportunities and constraints of Tele-AAC in all aspects of service delivery. These include, but are not limited to: needs assessments; implementation planning; device/system procurement, set-up and training; quality assurance, client progress monitoring, and follow-up service delivery. Tele-AAC, like other telepractice applications, requires adherence to the ASHA Code of Ethics and other policy documents, and state, federal, and international laws, as well as a competent technological infrastructure. The Working Group recommends that institutions of higher education and professional organizations provide training in Tele-AAC service provision. In addition, research and development are needed to create validity measures across Tele-AAC practices (i.e., assessment, implementation, and consultation; determine the communication competence levels achieved  by Tele-AAC users; discern stakeholders’  perceptions of Tele-AAC services (e.g., acceptability and viability; maximize Tele-AAC’s capacity to engage multiple team members in AAC assessment and ongoing service; identify the limitations and barriers of Tele-AAC provision; and develop potential solutions. 

  5. Quantitative super-resolution microscopy

    NARCIS (Netherlands)

    Harkes, Rolf

    2016-01-01

    Super-Resolution Microscopy is an optical fluorescence technique. In this thesis we focus on single molecule super-resolution, where the position of single molecules is determined. Typically these molecules can be localized with a 10 to 30nm precision. This technique is applied in four different

  6. Equalization equations in reactant resolution

    Indian Academy of Sciences (India)

    Unknown

    reactant, atoms-in-molecule, orbital, and local resolutions. In this paper ... resolution, i.e., the mutually polarized reactants before the charge-transfer among them. ..... and Komorowski L 2005 Int. J. Quantum Chem. 101. 703. 23. (a) Meneses L, Tiznado W, Contreras R and Fuen- tealba P 2004 Chem. Phys. Lett. 383 181. 24.

  7. "Planar" Tautologies Hard for Resolution

    DEFF Research Database (Denmark)

    Dantchev, Stefan; Riis, Søren

    2001-01-01

    We prove exponential lower bounds on the resolution proofs of some tautologies, based on rectangular grid graphs. More specifically, we show a 2Ω(n) lower bound for any resolution proof of the mutilated chessboard problem on a 2n×2n chessboard as well as for the Tseitin tautology (G. Tseitin, 196...

  8. Super resolution volume rendering hardware

    NARCIS (Netherlands)

    Bosma, Marco; Smit, Jaap; Terwisscha van Scheltinga, Jeroen

    1995-01-01

    The resolution obtained in volume rendering is greatly increased over known methods through the introduction of super resolution techniques which make it possible to enlarge the view o f the dataset without the introduction of unnecessary positional, gradient and opacity errors. In this paper our

  9. Super-resolution Phase Tomography

    KAUST Repository

    Depeursinge, Christian

    2013-04-21

    Digital Holographic Microscopy (DHM) yields reconstructed complex wavefields. It allows synthesizing the aperture of a virtual microscope up to 2π, offering super-resolution phase images. Live images of micro-organisms and neurons with resolution less than 100 nm are presented.

  10. Enhanced High Resolution RBS System

    Science.gov (United States)

    Pollock, Thomas J.; Hass, James A.; Klody, George M.

    2011-06-01

    Improvements in full spectrum resolution with the second NEC high resolution RBS system are summarized. Results for 50 Å TiN/HfO films on Si yielding energy resolution on the order of 1 keV are also presented. Detector enhancements include improved pulse processing electronics, upgraded shielding for the MCP/RAE detector, and reduced noise generated from pumping. Energy resolution measurements on spectra front edge coupled with calculations using 0.4mStr solid angle show that beam energy spread at 400 KeV from the Pelletron® accelerator is less than 100 eV. To improve user throughput, magnet control has been added to the automatic data collection. Depth profiles derived from experimental data are discussed. For the thin films profiled, depth resolutions were on the Angstrom level with the non-linear energy/channel conversions ranging from 100 to 200 eV.

  11. Gaspra - Highest Resolution Mosaic

    Science.gov (United States)

    1992-01-01

    This picture of asteroid 951 Gaspra is a mosaic of two images taken by the Galileo spacecraft from a range of 5,300 kilometers (3,300 miles), some 10 minutes before closest approach on October 29, 1991. The Sun is shining from the right; phase angle is 50 degrees. The resolution, about 54 meters/pixel, is the highest for the Gaspra encounter and is about three times better than that in the view released in November 1991. Additional images of Gaspra remain stored on Galileo's tape recorder, awaiting playback in November. Gaspra is an irregular body with dimensions about 19 x 12 x 11 kilometers (12 x 7.5 x 7 miles). The portion illuminated in this view is about 18 kilometers (11 miles) from lower left to upper right. The north pole is located at upper left; Gaspra rotates counterclockwise every 7 hours. The large concavity on the lower right limb is about 6 kilometers (3.7 miles) across, the prominent crater on the terminator, center left, about 1.5 kilometers (1 mile). A striking feature of Gaspra's surface is the abundance of small craters. More than 600 craters, 100-500 meters (330-1650 feet) in diameter are visible here. The number of such small craters compared to larger ones is much greater for Gaspra than for previously studied bodies of comparable size such as the satellites of Mars. Gaspra's very irregular shape suggests that the asteroid was derived from a larger body by nearly catastrophic collisions. Consistent with such a history is the prominence of groove-like linear features, believed to be related to fractures. These linear depressions, 100-300 meters wide and tens of meters deep, are in two crossing groups with slightly different morphology, one group wider and more pitted than the other. Grooves had previously been seen only on Mars's moon Phobos, but were predicted for asteroids as well. Gaspra also shows a variety of enigmatic curved depressions and ridges in the terminator region at left. The Galileo project, whose primary mission is the

  12. Highest Resolution Gaspra Mosaic

    Science.gov (United States)

    1992-01-01

    This picture of asteroid 951 Gaspra is a mosaic of two images taken by the Galileo spacecraft from a range of 5,300 kilometers (3,300 miles), some 10 minutes before closest approach on October 29, 1991. The Sun is shining from the right; phase angle is 50 degrees. The resolution, about 54 meters/pixel, is the highest for the Gaspra encounter and is about three times better than that in the view released in November 1991. Additional images of Gaspra remain stored on Galileo's tape recorder, awaiting playback in November. Gaspra is an irregular body with dimensions about 19 x 12 x 11 kilometers (12 x 7.5 x 7 miles). The portion illuminated in this view is about 18 kilometers (11 miles) from lower left to upper right. The north pole is located at upper left; Gaspra rotates counterclockwise every 7 hours. The large concavity on the lower right limb is about 6 kilometers (3.7 miles) across, the prominent crater on the terminator, center left, about 1.5 kilometers (1 mile). A striking feature of Gaspra's surface is the abundance of small craters. More than 600 craters, 100-500 meters (330-1650 feet) in diameter are visible here. The number of such small craters compared to larger ones is much greater for Gaspra than for previously studied bodies of comparable size such as the satellites of Mars. Gaspra's very irregular shape suggests that the asteroid was derived from a larger body by nearly catastrophic collisions. Consistent with such a history is the prominence of groove-like linear features, believed to be related to fractures. These linear depressions, 100-300 meters wide and tens of meters deep, are in two crossing groups with slightly different morphology, one group wider and more pitted than the other. Grooves had previously been seen only on Mars's moon Phobos, but were predicted for asteroids as well. Gaspra also shows a variety of enigmatic curved depressions and ridges in the terminator region at left. The Galileo project, whose primary mission is the

  13. A revised calibration of the interferometric mode of the CryoSat-2 radar altimeter improves ice height and height change measurements in western Greenland

    Science.gov (United States)

    Gray, Laurence; Burgess, David; Copland, Luke; Dunse, Thorben; Langley, Kirsty; Moholdt, Geir

    2017-05-01

    We compare geocoded heights derived from the interferometric mode (SARIn) of CryoSat to surface heights from calibration-validation sites on Devon Ice Cap and western Greenland. Comparisons are included for both the heights derived from the first return (the point-of-closest-approach or POCA) and heights derived from delayed waveform returns (swath processing). While swath-processed heights are normally less precise than edited POCA heights, e.g. standard deviations of ˜ 3 and ˜ 1.5 m respectively for the western Greenland site, the increased coverage possible with swath data complements the POCA data and provides useful information for both system calibration and improving digital elevation models (DEMs). We show that the pre-launch interferometric baseline coupled with an additional roll correction ( ˜ 0.0075° ± 0.0025°), or equivalent phase correction ( ˜ 0.0435 ± 0.0145 radians), provides an improved calibration of the interferometric SARIn mode. We extend the potential use of SARIn data by showing the influence of surface conditions, especially melt, on the return waveforms and that it is possible to detect and measure the height of summer supraglacial lakes in western Greenland. A supraglacial lake can provide a strong radar target in the waveform, stronger than the initial POCA return, if viewed at near-normal incidence. This provides an ideal situation for swath processing and we demonstrate a height precision of ˜ 0.5 m for two lake sites, one in the accumulation zone and one in the ablation zone, which were measured every year from 2010 or 2011 to 2016. Each year the lake in the ablation zone was viewed in June by ascending passes and then 5.5 days later by descending passes, which allows an approximate estimate of the filling rate. The results suggest that CryoSat waveform data and measurements of supraglacial lake height change could complement the use of optical satellite imagery and be helpful as proxy indicators for surface melt around

  14. High-Resolution Force Balance Analyses of Tidewater Glacier Dynamics

    Science.gov (United States)

    Enderlin, E. M.; Hamilton, G. S.; O'Neel, S.

    2015-12-01

    Changes in glacier velocity, thickness, and terminus position have been used to infer the dynamic response of tidewater glaciers to environmental perturbations, yet few analyses have attempted to quantify the associated variations in the glacier force balance. Where repeat high-resolution ice thickness and velocity estimates are available, force balance time series can be constructed to investigate the redistribution of driving and resistive forces associated with changes in terminus position. Comparative force balance analyses may, therefore, help us understand the variable dynamic response observed for glaciers in close proximity to each other. Here we construct force balance time series for Helheim Glacier, SE Greenland, and Columbia Glacier, SE Alaska, to investigate differences in dynamic sensitivity to terminus position change. The analysis relies on in situ and remotely sensed observations of ice thickness, velocity, and terminus position. Ice thickness time series are obtained from stereo satellite image-derived surface elevation and continuity-derived bed elevations that are constrained by airborne radar observations. Surface velocity time series are obtained from interferometric synthetic aperture radar (InSAR) observations. Approximately daily terminus positions are from a combination of satellite images and terrestrial time-lapse photographs. Helheim and Columbia glaciers are two of the best-studied Arctic tidewater glaciers with comprehensive high-resolution observational time series, yet we find that bed elevation uncertainties and poorly-constrained stress-coupling length estimates still hinder the analysis of spatial and temporal force balance variations. Here we use a new observationally-based method to estimate the stress-coupling length which successfully reduces noise in the derived force balance but preserves spatial variations that can be over-smoothed when estimating the stress-coupling length as a scalar function of the ice thickness

  15. Super-resolution biomolecular crystallography with low-resolution data.

    Science.gov (United States)

    Schröder, Gunnar F; Levitt, Michael; Brunger, Axel T

    2010-04-22

    X-ray diffraction plays a pivotal role in the understanding of biological systems by revealing atomic structures of proteins, nucleic acids and their complexes, with much recent interest in very large assemblies like the ribosome. As crystals of such large assemblies often diffract weakly (resolution worse than 4 A), we need methods that work at such low resolution. In macromolecular assemblies, some of the components may be known at high resolution, whereas others are unknown: current refinement methods fail as they require a high-resolution starting structure for the entire complex. Determining the structure of such complexes, which are often of key biological importance, should be possible in principle as the number of independent diffraction intensities at a resolution better than 5 A generally exceeds the number of degrees of freedom. Here we introduce a method that adds specific information from known homologous structures but allows global and local deformations of these homology models. Our approach uses the observation that local protein structure tends to be conserved as sequence and function evolve. Cross-validation with R(free) (the free R-factor) determines the optimum deformation and influence of the homology model. For test cases at 3.5-5 A resolution with known structures at high resolution, our method gives significant improvements over conventional refinement in the model as monitored by coordinate accuracy, the definition of secondary structure and the quality of electron density maps. For re-refinements of a representative set of 19 low-resolution crystal structures from the Protein Data Bank, we find similar improvements. Thus, a structure derived from low-resolution diffraction data can have quality similar to a high-resolution structure. Our method is applicable to the study of weakly diffracting crystals using X-ray micro-diffraction as well as data from new X-ray light sources. Use of homology information is not restricted to X

  16. Evaluation of InSAR and TomoSAR for Monitoring Deformations Caused by Mining in a Mountainous Area with High Resolution Satellite-Based SAR

    Directory of Open Access Journals (Sweden)

    Donglie Liu

    2014-02-01

    Full Text Available Interferometric Synthetic Aperture Radar (InSAR and Differential Interferometric Synthetic Aperture Radar (DInSAR have shown numerous applications for subsidence monitoring. In the past 10 years, the Persistent Scatterer InSAR (PSI and Small BAseline Subset (SBAS approaches were developed to overcome the problem of decorrelation and atmospheric effects, which are common in interferograms. However, DInSAR or PSI applications in rural areas, especially in mountainous regions, can be extremely challenging. In this study we have employed a combined technique, i.e., SBAS-DInSAR, to a mountainous area that is severely affected by mining activities. In addition, L-band (ALOS and C-band (ENVISAT data sets, 21 TerraSAR-X images provided by German Aerospace Center (DLR with a high resolution have been used. In order to evaluate the ability of TerraSAR-X for mining monitoring, we present a case study of TerraSAR-X SAR images for Subsidence Hazard Boundary (SHB extraction. The resulting data analysis gives an initial evaluation of InSAR applications within a mountainous region where fast movements and big phase gradients are common. Moreover, the experiment of four-dimension (4-D Tomography SAR (TomoSAR for structure monitoring inside the mining area indicates a potential near all-wave monitoring, which is an extension of conventional InSAR.

  17. Second catalog of interferometric measurements of binary stars (McAlister and Hartkopf 1988): Documentation for the machine-readable version

    Science.gov (United States)

    Warren, Wayne H., Jr.

    1989-01-01

    The machine-readable version of the catalog, as it is currently being distributed from the Astronomical Data Center, is described. The catalog is a compilation of measurements of binary- and multiple-star systems obtained by speckle interferometric techniques; this version supersedes a previous edition of the catalog published in 1985. Stars that have been examined for multiplicity with negative results are included, in which case upper limits for the separation are given. The second version is expanded from the first in that a file of newly resolved systems and six cross-index files of alternate designations are included. The data file contains alternate identifications for the observed systems, epochs of observation, reported errors in position angles and separation, and bibliographical references.

  18. Mean angular diameters, distances, and pulsation modes of the classical Cepheids FF Aquilae and T Vulpeculae. CHARA/FLUOR near-infrared interferometric observations

    Science.gov (United States)

    Gallenne, A.; Kervella, P.; Mérand, A.; McAlister, H.; ten Brummelaar, T.; Coudé du Foresto, V.; Sturmann, J.; Sturmann, L.; Turner, N.; Farrington, C.; Goldfinger, P. J.

    2012-05-01

    We report the first angular diameter measurements of two classical Cepheids, FF Aql and T Vul, that we obtain using observations with the FLUOR instrument installed at the CHARA interferometric array. We derive average limb-darkened angular diameters of θLD = 0.878 ± 0.013 mas and θLD = 0.629 ± 0.013 mas, respectively, for FF Aql and T Vul. Combining these angular diameters with the HST-FGS trigonometric parallaxes leads to linear radii R = 33.6 ± 2.2 R⊙ and R = 35.6 ± 4.4 R⊙, respectively. The comparison with empirical and theoretical period-radius relations leads to the conclusion that these Cepheids are pulsating in their fundamental mode. The knowledge of this pulsation mode is of prime importance to calibrating the period-luminosity relation with a uniform sample of fundamental mode Cepheids.

  19. Small-scale loess landslide monitoring with small baseline subsets interferometric synthetic aperture radar technique-case study of Xingyuan landslide, Shaanxi, China

    Science.gov (United States)

    Zhao, Chaoying; Zhang, Qin; He, Yang; Peng, Jianbing; Yang, Chengsheng; Kang, Ya

    2016-04-01

    Small baseline subsets interferometric synthetic aperture radar technique is analyzed to detect and monitor the loess landslide in the southern bank of the Jinghe River, Shaanxi province, China. Aiming to achieve the accurate preslide time-series deformation results over small spatial scale and abrupt temporal deformation loess landslide, digital elevation model error, coherence threshold for phase unwrapping, and quality of unwrapping interferograms must be carefully checked in advance. In this experience, land subsidence accompanying a landslide with the distance sound precursor for small-scale loess landslide detection. Moreover, the longer and continuous land subsidence has been monitored while deformation starting point for the landslide is successfully inverted, which is key to monitoring the similar loess landslide. In addition, the accelerated landslide deformation from one to two months before the landslide can provide a critical clue to early warning of this kind of landslide.

  20. Direct Polishing of Full-Shell, High-Resolution X-Ray Optics

    Science.gov (United States)

    Roche, Jacqueline M.; Gubarev, Mikhail V.; Smith, W. Scott; O'Dell, Stephen L.; Kolodziejczak, Jeffrey J.; Weisskopf, Martin C.; Ramsey, Brian D.; Elsner, Ronald F.

    2014-01-01

    Future x-ray telescopes will likely require lightweight mirrors to attain the large collecting areas needed to accomplish the science objectives. Understanding and demonstrating processes now is critical to achieving sub-arcsecond performance in the future. Consequently, designs not only of the mirrors but of fixtures for supporting them during fabrication, metrology, handling, assembly, and testing must be adequately modeled and verified. To this end, MSFC is using finite-element modeling to study the effects of mounting on thin, full-shell grazing-incidence mirrors, during all processes leading to a flight.

  1. High-resolution Mapping of Offshore and Onshore Glaciogenic Features in Melville Bay, Northwestern Greenland

    Science.gov (United States)

    Freire, F.; Gyllencreutz, R.; Greenwood, S.; Mayer, L. A.; Jakobsson, M.

    2014-12-01

    This study presents results from high resolution mapping in the northwestern part of Greenland's continental shelf, offshore from the Greenland Ice Sheet. The study area is located at about 74o30'N and 58 o40'W where high-resolution seafloor imagery were collected from ~200-500 m water depth. These data were analyzed and compared to existing high-resolution satellite imagery of exposed glacial landforms from the nearby coastal areas. Offshore geophysical mapping equipment consisted of a Kongsberg EM2040 multibeam that was bow-mounted on the sailing vessel Explorer of Sweden together with a Seatex MRU5+ motion sensor and GPS antennas. In addition, a GAVIA autonomous underwater vehicle (AUV) from University of Iceland with installed Geoswath interfometric sonar and Marine Sonic side-scan was used. The data from these systems permitted the production of both 5-m (for the EM2040) and 2-m (for the Geoswath) resolution bathymetric grids for landform analyzes. Sediment characterization analysis was also undertaken using the co-registered backscatter data. The exposed onshore landforms were studied using data from the high-res QuickBird satellite images with a 2-m pixel resolution. Geomorphic analysis of the data shows that past tectonic and glacial scouring processes have shaped the present-day landscape in both the offshore and onshore study areas. The terrain consists of glacially eroded bedrock covered with very thin surficial sediments resembling a 'cnoc-and-lochan' terrain, although the degree of erosion varies spatially, probably as a result of local variations in the rock properties. Different glacially influenced features are identified and described in the study. These features have been used to understand and infer past ice-sheet processes, particularly ice-flow direction and the extent of ice-cover on the continental shelves from previous extreme glaciation events. The backscatter information from the high-resolution interferometric sonar show fine

  2. War Powers Resolution: Presidential Compliance

    National Research Council Canada - National Science Library

    Grimmett, Richard F

    2009-01-01

    .... One issue concerns the division of war powers between the President and Congress, whether the use of armed forces falls within the purview of the congressional power to declare war and the War Powers Resolution (WPR...

  3. House passes resolution on occupation

    Index Scriptorium Estoniae

    2005-01-01

    Venemaalt Baltimaade okupeerimise tunnistamist nõudva resolutsiooni vastuvõtmisest USA Kongressi Esindajate Kojas Leedu päritolu kongressmani John Shimkuse eestvedamisel. Vt. ka resolutsiooni teksti "House Concurrent Resolution 128" lk. 14

  4. High Spatiotemporal Resolution Prostate MRI

    Science.gov (United States)

    2017-09-01

    AWARD NUMBER: W81XWH-15-1-0341 TITLE: High Spatiotemporal Resolution Prostate MRI PRINCIPAL INVESTIGATOR: Stephen J. Riederer, Ph.D...Resolution Prostate MRI 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-15-1-0341 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Stephen J. Riederer E-Mail...overall purpose of this project is to develop improved means using MRI for detecting prostate cancer with the potential for differentiating disease

  5. High-resolution neutron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Mikerov, V.I. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Zhitnik, I.A. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Ignat`ev, A.P. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Isakov, A.I. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Korneev, V.V. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Krutov, V.V. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Kuzin, S.V. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Oparin, S.N. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Pertsov, A.A. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Podolyak, E.R. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Sobel`man, I.I. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Tindo, I.P. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation); Tukarev, B.A. [P.N. Lebedev Physical Inst., RAN, Moscow (Russian Federation)

    1995-12-31

    A neutron tomography technique with a coordinate resolution of several tens of micrometers has been developed. Our results indicate that the technique resolves details with dimensions less than 100 {mu}m and measures a linear attenuation of less than {approx} 0.1 cm{sup -1}. Tomograms can be reconstructed using incomplete data. Limits on the resolution of the restored pattern are analyzed, and ways to improve the sensitivity of the technique are discussed. (orig.).

  6. Enhanced Contention Resolution Aloha - ECRA

    OpenAIRE

    Clazzer, Federico; Kissling, Christian

    2012-01-01

    Random Access (RA) Medium Access (MAC) protocols are simple and effective when the nature of the traffic is unpredictable and random. In the following paper, a novel RA protocol called Enhanced Contention Resolution ALOHA (ECRA) is presented. This evolution, based on the previous Contention Resolution ALOHA (CRA) protocol, exploits the nature of the interference in unslotted Aloha-like channels for trying to resolve most of the partial collision that can occur there. I...

  7. Estimating uncertainty in resolution tests

    CSIR Research Space (South Africa)

    Goncalves, DP

    2006-05-01

    Full Text Available frequencies yields a biased estimate, and we provide an improved estimator. An application illustrates how the results derived can be incorporated into a larger un- certainty analysis. ? 2006 Society of Photo-Optical Instrumentation Engineers. H20851DOI: 10....1117/1.2202914H20852 Subject terms: resolution testing; USAF 1951 test target; resolution uncertainity. Paper 050404R received May 20, 2005; revised manuscript received Sep. 2, 2005; accepted for publication Sep. 9, 2005; published online May 10, 2006. 1...

  8. Frequency resolution and hearing loss.

    Science.gov (United States)

    Tyler, R S; Wood, E J; Fernandes, M

    1982-02-01

    Future scientific and diagnostic interest in frequency resolution requires an evaluation of the different methods that are available to measure it. We compared three methods: (1) pure-tone thresholds in broadband noise, (2) pure-tone thresholds in the presence of a fixed pure-tone masker and (3) psychoacoustical tuning curves. We additionally obtained estimates of temporal integration and of speech intelligibility in noise. Three subject groups were tested: 10 normals, 13 subjects with a noise-induced hearing loss and 18 subjects with a cochlear hearing loss but no history of noise exposure. Generally the three measures of frequency resolution show moderate agreement with each other. Poor frequency resolution is invariably associated with a pure-tone threshold loss. Temporal integration appears unrelated either to the pure-tone threshold loss or frequency resolution. Some of the measures of frequency resolution display significant correlation with speech intelligibility in noise. However, since both variables are correlated with pure-tone threshold loss the exact relationship between frequency resolution and speech intelligibility cannot be clearly established.

  9. Single Image Super Resolution via Sparse Reconstruction

    NARCIS (Netherlands)

    Kruithof, M.C.; Eekeren, A.W.M. van; Dijk, J.; Schutte, K.

    2012-01-01

    High resolution sensors are required for recognition purposes. Low resolution sensors, however, are still widely used. Software can be used to increase the resolution of such sensors. One way of increasing the resolution of the images produced is using multi-frame super resolution algorithms.

  10. A NEW HIGH-RESOLUTION ELEVATION MODEL OF GREENLAND DERIVED FROM TANDEM-X

    Directory of Open Access Journals (Sweden)

    B. Wessel

    2016-06-01

    Full Text Available In this paper we present for the first time the new digital elevation model (DEM for Greenland produced by the TanDEM-X (TerraSAR add-on for digital elevation measurement mission. The new, full coverage DEM of Greenland has a resolution of 0.4 arc seconds corresponding to 12 m. It is composed of more than 7.000 interferometric synthetic aperture radar (InSAR DEM scenes. X-Band SAR penetrates the snow and ice pack by several meters depending on the structures within the snow, the acquisition parameters, and the dielectricity constant of the medium. Hence, the resulting SAR measurements do not represent the surface but the elevation of the mean phase center of the backscattered signal. Special adaptations on the nominal TanDEM-X DEM generation are conducted to maintain these characteristics and not to raise or even deform the DEM to surface reference data. For the block adjustment, only on the outer coastal regions ICESat (Ice, Cloud, and land Elevation Satellite elevations as ground control points (GCPs are used where mostly rock and surface scattering predominates. Comparisons with ICESat data and snow facies are performed. In the inner ice and snow pack, the final X-Band InSAR DEM of Greenland lies up to 10 m below the ICESat measurements. At the outer coastal regions it corresponds well with the GCPs. The resulting DEM is outstanding due to its resolution, accuracy and full coverage. It provides a high resolution dataset as basis for research on climate change in the arctic.

  11. Speckle-interferometric measurement system of 3D deformation to obtain thickness changes of thin specimen under tensile loads

    Science.gov (United States)

    Kowarsch, Robert; Zhang, Jiajun; Sguazzo, Carmen; Hartmann, Stefan; Rembe, Christian

    2017-06-01

    The analysis of materials and geometries in tensile tests and the extraction of mechanic parameters is an important field in solid mechanics. Especially the measurement of thickness changes is important to obtain accurate strain information of specimens under tensile loads. Current optical measurement methods comprising 3D digital image correlation enable thickness-change measurement only with nm-resolution. We present a phase-shifting electronic speckle-pattern interferometer in combination with speckle-correlation technique to measure the 3D deformation. The phase-shift for the interferometer is introduced by fast wavelength tuning of a visible diode laser by injection current. In a post-processing step, both measurements can be combined to reconstruct the 3D deformation. In this contribution, results of a 3Ddeformation measurement for a polymer membrane are presented. These measurements show sufficient resolution for the detection of 3D deformations of thin specimen in tensile test. In future work we address the thickness changes of thin specimen under tensile loads.

  12. Application of seismic interferometric migration for shallow seismic high precision data processing: A case study in the Shenhu area

    Science.gov (United States)

    Wei, Jia; Liu, Huaishan; Xing, Lei; Du, Dong

    2018-02-01

    The stability of submarine geological structures has a crucial influence on the construction of offshore engineering projects and the exploitation of seabed resources. Marine geologists should possess a detailed understanding of common submarine geological hazards. Current marine seismic exploration methods are based on the most effective detection technologies. Therefore, current research focuses on improving the resolution and precision of shallow stratum structure detection methods. In this article, the feasibility of shallow seismic structure imaging is assessed by building a complex model, and differences between the seismic interferometry imaging method and the traditional imaging method are discussed. The imaging effect of the model is better for shallow layers than for deep layers because coherent noise produced by this method can result in an unsatisfactory imaging effect for deep layers. The seismic interference method has certain advantages for geological structural imaging of shallow submarine strata, which indicates continuous horizontal events, a high resolution, a clear fault, and an obvious structure boundary. The effects of the actual data applied to the Shenhu area can fully illustrate the advantages of the method. Thus, this method has the potential to provide new insights for shallow submarine strata imaging in the area.

  13. Section on High Resolution Optical Imaging (HROI)

    Data.gov (United States)

    Federal Laboratory Consortium — The Section on High Resolution Optical Imaging (HROI) develops novel technologies for studying biological processes at unprecedented speed and resolution. Research...

  14. Resolution in forensic microbial genotyping

    Energy Technology Data Exchange (ETDEWEB)

    Velsko, S P

    2005-08-30

    Resolution is a key parameter for differentiating among the large number of strain typing methods that could be applied to pathogens involved in bioterror events or biocrimes. In this report we develop a first-principles analysis of strain typing resolution using a simple mathematical model to provide a basis for the rational design of microbial typing systems for forensic applications. We derive two figures of merit that describe the resolving power and phylogenetic depth of a strain typing system. Rough estimates of these figures-of-merit for MLVA, MLST, IS element, AFLP, hybridization microarrays, and other bacterial typing methods are derived from mutation rate data reported in the literature. We also discuss the general problem of how to construct a ''universal'' practical typing system that has the highest possible resolution short of whole-genome sequencing, and that is applicable with minimal modification to a wide range of pathogens.

  15. KINOFORM LENSES - TOWARD NANOMETER RESOLUTION.

    Energy Technology Data Exchange (ETDEWEB)

    STEIN, A.; EVANS-LUTTERODT, K.; TAYLOR, A.

    2004-10-23

    While hard x-rays have wavelengths in the nanometer and sub-nanometer range, the ability to focus them is limited by the quality of sources and optics, and not by the wavelength. A few options, including reflective (mirrors), diffractive (zone plates) and refractive (CRL's) are available, each with their own limitations. Here we present our work with kinoform lenses which are refractive lenses with all material causing redundant 2{pi} phase shifts removed to reduce the absorption problems inherently limiting the resolution of refractive lenses. By stacking kinoform lenses together, the effective numerical aperture, and thus the focusing resolution, can be increased. The present status of kinoform lens fabrication and testing at Brookhaven is presented as well as future plans toward achieving nanometer resolution.

  16. Requirements on high resolution detectors

    Energy Technology Data Exchange (ETDEWEB)

    Koch, A. [European Synchrotron Radiation Facility, Grenoble (France)

    1997-02-01

    For a number of microtomography applications X-ray detectors with a spatial resolution of 1 {mu}m are required. This high spatial resolution will influence and degrade other parameters of secondary importance like detective quantum efficiency (DQE), dynamic range, linearity and frame rate. This note summarizes the most important arguments, for and against those detector systems which could be considered. This article discusses the mutual dependencies between the various figures which characterize a detector, and tries to give some ideas on how to proceed in order to improve present technology.

  17. High Resolution Processing with an Active Phased Array SAR

    NARCIS (Netherlands)

    Nijenboer, F.J.; Otten, M.P.G.

    1999-01-01

    The Dutch PHARUS system is a polarimetric active phased array SAR capable of performing advanced SAR modes. Advanced SAR modes that are being investigated are: spotlight SAR, sliding spotlight SAR, stepped frequency SAR and interferometric SAR. The flight experiments and automatic beam steering

  18. The High Angular Resolution Multiplicity of Massive Stars

    Science.gov (United States)

    2009-02-01

    binaries: visual – stars: early-type – stars: individual (iota Ori, delta Ori, delta Sco) – techniques: interferometric Online-only material...26 Inf. Circ., 135 Ling, J. F., Prieto, C., & Magdalena , P. 2005, IAU Comm. 26 Inf. Circ., 155 Maı́z-Apellániz, J., Walborn, N.R., Galue, H.A., & Wei

  19. Modelling high resolution ALMA observations of strongly lensed highly star forming galaxies detected by Herscheltype="fn" rid="fn1" />

    Science.gov (United States)

    Dye, S.; Furlanetto, C.; Dunne, L.; Eales, S. A.; Negrello, M.; Nayyeri, H.; van der Werf, P. P.; Serjeant, S.; Farrah, D.; Michałowski, M. J.; Baes, M.; Marchetti, L.; Cooray, A.; Riechers, D. A.; Amvrosiadis, A.

    2018-02-01

    We have modelled ˜0.1 arcsec resolution ALMA imaging of six strong gravitationally lensed galaxies detected by the Herschel Space Observatory. Our modelling recovers mass properties of the lensing galaxies and, by determining magnification factors, intrinsic properties of the lensed sub-millimetre sources. We find that the lensed galaxies all have high ratios of star formation rate to dust mass, consistent with or higher than the mean ratio for high redshift sub-millimetre galaxies and low redshift ultra-luminous infra-red galaxies. Source reconstruction reveals that most galaxies exhibit disturbed morphologies. Both the cleaned image plane data and the directly observed interferometric visibilities have been modelled, enabling comparison of both approaches. In the majority of cases, the recovered lens models are consistent between methods, all six having mass density profiles that are close to isothermal. However, one system with poor signal to noise shows mildly significant differences.

  20. Global carbon monoxide vertical distributions from spaceborne high-resolution FTIR nadir measurements

    Directory of Open Access Journals (Sweden)

    B. Barret

    2005-01-01

    Full Text Available This paper presents the first global distributions of CO vertical profiles retrieved from a thermal infrared FTS working in the nadir geometry. It is based on the exploitation of the high resolution and high quality spectra measured by the Interferometric Monitor of Greenhouse gases (IMG which flew onboard the Japanese ADEOS platform in 1996-1997. The retrievals are performed with an algorithm based on the Optimal Estimation Method (OEM and are characterized in terms of vertical sensitivity and error budget. It is found that most of the IMG measurements contain between 1.5 and 2.2 independent pieces of information about the vertical distribution of CO from the lower troposphere to the upper troposphere-lower stratosphere (UTLS. The retrievals are validated against coincident NOAA/CMDL in situ surface measurements and NDSC/FTIR total columns measurements. The retrieved global distributions of CO are also found to be in good agreement with the distributions modeled by the GEOS-CHEM 3D CTM, highlighting the ability of IMG to capture the horizontal as well as the vertical structure of the CO distributions.

  1. Expressway deformation mapping using high-resolution TerraSAR-X images

    KAUST Repository

    Shi, Xuguo

    2014-01-27

    Monitoring deformation of linear infrastructures such as expressway and railway caused by natural processes or anthropogenic activities is a vital task to ensure the safety of human lives and properties. Interferometric Synthetic Aperture Radar (InSAR) has been widely recognized as an effective technology to carry out large-area surface deformation mapping. However, its application in linear infrastructure deformation monitoring has not been intensively studied till now. In this article, a modified Small BAseline Subset (SBAS) method is proposed to retrieve the deformation patterns of the expressway. In our method, only the point-like targets identified on the expressway were kept in our analysis, and two complementary subsets of interferograms were formed to better separate the signals of height error and deformation from inteferometric phase observations. We successfully applied this method with multitemporal high-resolution TerraSAR-X images to retrieve the spatialoral pattern of surface deformation along the Beian-Heihe expressway that is located in island-permafrost areas and threatened by geohazards. © 2014 Taylor & Francis.

  2. High-resolution all-optical photoacoustic imaging system for remote interrogation of biological specimens

    Science.gov (United States)

    Sampathkumar, Ashwin

    2014-05-01

    Conventional photoacoustic imaging (PAI) employs light pulses to produce a photoacoustic (PA) effect and detects the resulting acoustic waves using an ultrasound transducer acoustically coupled to the target tissue. The resolution of conventional PAI is limited by the sensitivity and bandwidth of the ultrasound transducer. We have developed an all-optical versatile PAI system for characterizing ex vivo and in vivo biological specimens. The system employs noncontact interferometric detection of the acoustic signals that overcomes limitations of conventional PAI. A 532-nm pump laser with a pulse duration of 5 ns excited the PA effect in tissue. Resulting acoustic waves produced surface displacements that were sensed using a 532-nm continuous-wave (CW) probe laser in a Michelson interferometer with a GHz bandwidth. The pump and probe beams were coaxially focused using a 50X objective giving a diffraction-limited spot size of 0.48 μm. The phase-encoded probe beam was demodulated using a homodyne interferometer. The detected time-domain signal was time reversed using k-space wave-propagation methods to produce a spatial distribution of PA sources in the target tissue. Performance was assessed using PA images of ex vivo rabbit lymph node specimens and human tooth samples. A minimum peak surface displacement sensitivity of 0.19 pm was measured. The all-optical PAI (AOPAI) system is well suited for assessment of retinal diseases, caries lesion detection, skin burns, section less histology and pressure or friction ulcers.

  3. Sub-Airy disk angular resolution with high dynamic range in the near-infrared

    Directory of Open Access Journals (Sweden)

    Richichi A.

    2011-07-01

    Full Text Available Lunar occultations (LO are a simple and effective high angular resolution method, with minimum requirements in instrumentation and telescope time. They rely on the analysis of the diffraction fringes created by the lunar limb. The diffraction phenomen occurs in space, and as a result LO are highly insensitive to most of the degrading effects that limit the performance of traditional single telescope and long-baseline interferometric techniques used for direct detection of faint, close companions to bright stars. We present very recent results obtained with the technique of lunar occultations in the near-IR, showing the detection of companions with very high dynamic range as close as few milliarcseconds to the primary star. We discuss the potential improvements that could be made, to increase further the current performance. Of course, LO are fixed-time events applicable only to sources which happen to lie on the Moon’s apparent orbit. However, with the continuously increasing numbers of potential exoplanets and brown dwarfs beign discovered, the frequency of such events is not negligible. I will list some of the most favorable potential LO in the near future, to be observed from major observatories.

  4. SOLAR FLARE CHROMOSPHERIC LINE EMISSION: COMPARISON BETWEEN IBIS HIGH-RESOLUTION OBSERVATIONS AND RADIATIVE HYDRODYNAMIC SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Fatima Rubio da; Petrosian, Vahé [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Kleint, Lucia [University of Applied Sciences and Arts Northwestern Switzerland, 5210 Windisch (Switzerland); Dalda, Alberto Sainz [Stanford-Lockheed Institute for Space Research, Stanford University, HEPL, 466 Via Ortega, Stanford, CA 94305 (United States); Liu, Wei, E-mail: frubio@stanford.edu [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Palo Alto, CA 94304 (United States)

    2015-05-01

    Solar flares involve impulsive energy release, which results in enhanced radiation over a broad spectral range and a wide range of heights. In particular, line emission from the chromosphere can provide critical diagnostics of plasma heating processes. Thus, a direct comparison between high-resolution spectroscopic observations and advanced numerical modeling results could be extremely valuable, but has not yet been attempted. In this paper, we present such a self-consistent investigation of an M3.0 flare observed by the Dunn Solar Telescope’s Interferometric Bi-dimensional Spectrometer (IBIS) on 2011 September 24 which we have modeled using the radiative hydrodynamic code RADYN. We obtained images and spectra of the flaring region with IBIS in Hα 6563 Å and Ca ii 8542 Å, and with RHESSI in X-rays. The latter observations were used to infer the non-thermal electron population, which was passed to RADYN to simulate the atmospheric response to electron collisional heating. We then synthesized spectral lines and compared their shapes and intensities to those observed by IBIS and found a general agreement. In particular, the synthetic Ca ii 8542 Å profile fits well to the observed profile, while the synthetic Hα profile is fainter in the core than for the observation. This indicates that Hα emission is more responsive to the non-thermal electron flux than the Ca ii 8542 Å emission. We suggest that it is necessary to refine the energy input and other processes to resolve this discrepancy.

  5. A Seamless, High-Resolution, Coastal Digital Elevation Model (DEM) for Southern California

    Science.gov (United States)

    Barnard, Patrick L.; Hoover, Daniel

    2010-01-01

    A seamless, 3-meter digital elevation model (DEM) was constructed for the entire Southern California coastal zone, extending 473 km from Point Conception to the Mexican border. The goal was to integrate the most recent, high-resolution datasets available (for example, Light Detection and Ranging (Lidar) topography, multibeam and single beam sonar bathymetry, and Interferometric Synthetic Aperture Radar (IfSAR) topography) into a continuous surface from at least the 20-m isobath to the 20-m elevation contour. This dataset was produced to provide critical boundary conditions (bathymetry and topography) for a modeling effort designed to predict the impacts of severe winter storms on the Southern California coast (Barnard and others, 2009). The hazards model, run in real-time or with prescribed scenarios, incorporates atmospheric information (wind and pressure fields) with a suite of state-of-the-art physical process models (tide, surge, and wave) to enable detailed prediction of water levels, run-up, wave heights, and currents. Research-grade predictions of coastal flooding, inundation, erosion, and cliff failure are also included. The DEM was constructed to define the general shape of nearshore, beach and cliff surfaces as accurately as possible, with less emphasis on the detailed variations in elevation inland of the coast and on bathymetry inside harbors. As a result this DEM should not be used for navigation purposes.

  6. Retrieval and analysis of a polarized high-spectral-resolution lidar for profiling aerosol optical properties.

    Science.gov (United States)

    Liu, Dong; Yang, Yongying; Cheng, Zhongtao; Huang, Hanlu; Zhang, Bo; Ling, Tong; Shen, Yibing

    2013-06-03

    Taking advantage of the broad spectrum of the Cabannes-Brillouin scatter from atmospheric molecules, the high spectral resolution lidar (HSRL) technique employs a narrow spectral filter to separate the aerosol and molecular scattering components in the lidar return signals and therefore can obtain the aerosol optical properties as well as the lidar ratio (i.e., the extinction-to-backscatter ratio) which is normally selected or modeled in traditional backscatter lidars. A polarized HSRL instrument, which employs an interferometric spectral filter, is under development at the Zhejiang University (ZJU), China. In this paper, the theoretical basis to retrieve the aerosol lidar ratio, depolarization ratio and extinction and backscatter coefficients, is presented. Error analyses and sensitivity studies have been carried out on the spectral transmittance characteristics of the spectral filter. The result shows that a filter that has as small aerosol transmittance (i.e., large aerosol rejection rate) and large molecular transmittance as possible is desirable. To achieve accurate retrieval, the transmittance of the spectral filter for molecular and aerosol scattering signals should be well characterized.

  7. Advantages to Geoscience and Disaster Response from QuakeSim Implementation of Interferometric Radar Maps in a GIS Database System

    Science.gov (United States)

    Parker, Jay; Donnellan, Andrea; Glasscoe, Margaret; Fox, Geoffrey; Wang, Jun; Pierce, Marlon; Ma, Yu

    2015-08-01

    High-resolution maps of earth surface deformation are available in public archives for scientific interpretation, but are primarily available as bulky downloads on the internet. The NASA uninhabited aerial vehicle synthetic aperture radar (UAVSAR) archive of airborne radar interferograms delivers very high resolution images (approximately seven meter pixels) making remote handling of the files that much more pressing. Data exploration requiring data selection and exploratory analysis has been tedious. QuakeSim has implemented an archive of UAVSAR data in a web service and browser system based on GeoServer (http://geoserver.org). This supports a variety of services that supply consistent maps, raster image data and geographic information systems (GIS) objects including standard earthquake faults. Browsing the database is supported by initially displaying GIS-referenced thumbnail images of the radar displacement maps. Access is also provided to image metadata and links for full file downloads. One of the most widely used features is the QuakeSim line-of-sight profile tool, which calculates the radar-observed displacement (from an unwrapped interferogram product) along a line specified through a web browser. Displacement values along a profile are updated to a plot on the screen as the user interactively redefines the endpoints of the line and the sampling density. The profile and also a plot of the ground height are available as CSV (text) files for further examination, without any need to download the full radar file. Additional tools allow the user to select a polygon overlapping the radar displacement image, specify a downsampling rate and extract a modest sized grid of observations for display or for inversion, for example, the QuakeSim simplex inversion tool which estimates a consistent fault geometry and slip model.

  8. RESOLUTION

    CERN Multimedia

    STAFF ASSOCIATION

    2010-01-01

    Research without a budget = Europe without a future !   Noting that the CERN Management has submitted to the Member States for the Finance Committee meeting on 25th August 2010 a budget for 2011 and a medium-term plan (MTP) for the period 2012-2015; Deploring the fact that, on the Member States’ request, this plan proposes a reduction of resources of 478 million Swiss francs over the period 2011–2015, compared to the initial proposal by the Management, which corresponded even then to the minimum needed to exploit the machines and experiments; Recalling that, following a decision by Council in 1996, CERN has suffered an annual budget cut of 100 million Swiss francs; Considering that this approach equates to an abandonment by the Member States of the European Union of a policy agreed upon in Barcelona in 2003 to invest 3% of their GDP in R&D by 2010, and today they can barely manage 1.85%; Considering that these budget cuts imposed on CERN compromise not on...

  9. Entity resolution for uncertain data

    NARCIS (Netherlands)

    Ayat, N.; Akbarinia, R.; Afsarmanesh, H.; Valduriez, P.

    2012-01-01

    Entity resolution (ER), also known as duplicate detection or record matching, is the problem of identifying the tuples that represent the same real world entity. In this paper, we address the problem of ER for uncertain data, which we call ERUD. We propose two different approaches for the ERUD

  10. African Journal on Conflict Resolution

    African Journals Online (AJOL)

    Envisaged readers are academic researchers, teachers and students and practitioners in the field of dealing with conflict. The African Journal on Conflict Resolution (AJCR) publishes the writings of a wide range of African and international authors in the field, but emphasis has deliberately been kept on African writers and ...

  11. Limits to Drift Chamber Resolution

    CERN Document Server

    Riegler, Werner

    1998-01-01

    ATLAS (A Large Toroidal LHC Apparatus) will be a general-purpose experiment at the Large Hadron Collider that will be operational at CERN in the year 2004. The ATLAS muon spectrometer aims for a momentum resolution of 10% for a transverse momentum of pT=1TeV. The precision tracking devices in the muon system will be high pressure drift tubes (MDTs) with a single wire resolution of 1100 chambers covering an area of ≈ 2500m2. The high counting rates in the spectrometer as well as the aim for excellent spatial resolution and high efficiency put severe constraints on the MDT operating parameters. This work describes a detailed study of all the resolution limiting factors in the ATLAS environment. A ’full chain’ simulation of the MDT response to photons and charged particles as well as quantitative comparisons with measurements was performed. The good agreement between simulation and measurements resulted in a profound understanding of the drift chamber processes and the individual contributions to the spat...

  12. Ambiguity Resolution in Lateralized Arabic

    Science.gov (United States)

    Hayadre, Manar; Kurzon, Dennis; Peleg, Orna; Zohar, Eviatar

    2015-01-01

    We examined ambiguity resolution in reading in Arabic. Arabic is an abjad orthography and is morphologically similar to Hebrew. However, Arabic literacy occurs in a diglossic context, and its orthography is more visually complex than Hebrew. We therefore tested to see whether hemispheric differences will be similar or different from previous…

  13. Processing of Interferometric Time-Series acquired with Ground-Based Radar for Mapping Deformation of the Calaveras Fault at Coyote Dam

    Science.gov (United States)

    Werner, C. L.; Baker, B.; Cassotto, R.; Wegmüller, U.; Roberstson, E.; Miller, K.; Fahnestock, M. A.

    2016-12-01

    A creeping section of the Calaveras fault passes directly through Coyote Dam, an earthen dam located 13 km northeast of Gilroy, CA. Aseismic deformation causes measurable deformation of the dam between 10 and 15 mm/year. Assessment of fault related deformation and determining the fault location relative to the dam structure are essential for evaluation of dam safety and planning a seismic retrofit. Terrestrial Radar Interferometry (TRI) has the capability to generate spatially continuous deformation maps due to fault creep and other processes with accuracy on the order of 0.1mm along the line of sight (LOS). TRI also permits multiple illumination directions required for 3D deformation mapping, the ability to acquire large numbers of observations (>500/day) to mitigate the effect of atmosphere on the interferometric phase, and near zero-baseline geometry reducing the need for high accuracy digital elevation models. The first phase of our radar investigation of Coyote Dam took place during February through July 2015. On the upstream face of the dam, the fault surface LOS deformation was very clearly delineated and the deformation was consistent with existing fault model. On the downstream side, the motion field was shown to be more complex with LOS motion from a single observation position that was difficult to reconcile with the existing model. This motion includes possible rotation of a large silicate/carbonate block within the fault zone. A follow-on campaign, begun in May 2016, aims to elucidate the 3D motion field on the down-stream side of the dam using 5 different observation positions including 4 new positions on the crest of the dam. This campaign aims to develop and demonstrate 1) improved methods for mitigation of atmospheric phase error using both radar reflector measurements and meteorological in-situ data, 2) a 3D least-squares solution for deformation using interferometric data from multiple observation points. A network of corner reflectors has been

  14. A near-infrared interferometric survey of debris disc stars. II. CHARA/FLUOR observations of six early-type dwarfs

    Science.gov (United States)

    Absil, O.; di Folco, E.; Mérand, A.; Augereau, J.-C.; Coudé du Foresto, V.; Defrère, D.; Kervella, P.; Aufdenberg, J. P.; Desort, M.; Ehrenreich, D.; Lagrange, A.-M.; Montagnier, G.; Olofsson, J.; ten Brummelaar, T. A.; McAlister, H. A.; Sturmann, J.; Sturmann, L.; Turner, N. H.

    2008-09-01

    Aims: We aim at directly detecting the presence of optically thin circumstellar dust emission within the terrestrial planetary zone around main sequence stars known to harbour cold debris discs. The present study focuses on a sample of six bright A- and early F-type stars. Methods: High-precision interferometric observations have been obtained in the near-infrared K band with the FLUOR instrument installed on the CHARA Array. The measured squared visibilities are compared to the expected visibility of the stellar photospheres based on theoretical photospheric models taking into account rotational distortion. We search for potential visibility reduction at short baselines, a direct piece of evidence for resolved circumstellar emission. Results: Our observations bring to light the presence of resolved circumstellar emission around one of the six target stars (ζ Aql) at the 5σ level. The morphology of the emission source cannot be directly constrained because of the sparse spatial frequency sampling of our interferometric data. Using complementary adaptive optics observations and radial velocity measurements, we find that the presence of a low-mass companion is a likely origin for the excess emission. The potential companion is characterised by a K-band contrast of four magnitudes. It has a most probable mass of about 0.6~M⊙ and is expected to orbit between about 5.5 AU and 8 AU from its host star assuming a purely circular orbit. Nevertheless, by adjusting a physical debris disc model to the observed Spectral Energy Distribution of the ζ Aql system, we also show that the presence of hot dust within 10 AU from ζ Aql, producing a total thermal emission equal to 1.69 ± 0.31% of the photospheric flux in the K band, is another viable explanation for the observed near-infrared excess. Our re-interpretation of archival near- to far-infrared photometric measurements shows however that cold dust is not present around ζ Aql at the sensitivity limit of the IRS and MIPS

  15. High resolution tomographic instrument development

    Energy Technology Data Exchange (ETDEWEB)

    1992-01-01

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefited greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational.

  16. High resolution tomographic instrument development

    Energy Technology Data Exchange (ETDEWEB)

    1992-08-01

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefited greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational.

  17. Interpretación sismotectónica de la serie sísmica de Gérgal (2002, Mw 4.8) mediante datos sismológicos y de interferometría de RADAR (INSAR)

    OpenAIRE

    Bejar, M.; Herráiz, E.; Martínez Díaz, J. J.; López, C.; Capote, Ramón; Tsige, Meaza

    2005-01-01

    This work analyzes the geological source of the Mw 4.8 February 4 2002, Gérgal earthquake. The interpretation of local geological data, the relocation of the aftershocks sequence using a local velocity model, the focal mechanism calculation and the interferometric study of the area using RADAR images give evidences that support a tensional stress source with a rupture plane oriented NW-SE to NNE-SSW

  18. High-Resolution Data for a Low-Resolution World

    Energy Technology Data Exchange (ETDEWEB)

    Brady, Brendan Williams [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-10

    In the past 15 years, the upper section of Cañon de Valle has been severely altered by wildfires and subsequent runoff events. Loss of root structures on high-angle slopes results in debris flow and sediment accumulation in the narrow canyon bottom. The original intent of the study described here was to better understand the changes occurring in watershed soil elevations over the course of several post-fire years. An elevation dataset from 5 years post-Cerro Grande fire was compared to high-resolution LiDAR data from 14 years post-Cerro Grande fire (also 3 years post-Las Conchas fire). The following analysis was motivated by a problematic comparison of these datasets of unlike resolution, and therefore focuses on what the data reveals of itself. The objective of this study is to highlight the effects vegetation can have on remote sensing data that intends to read ground surface elevation.

  19. A nanometre-scale resolution interference-based probe of interfacial phenomena between microscopic objects and surfaces

    Science.gov (United States)

    Contreras-Naranjo, Jose C.; Ugaz, Victor M.

    2013-01-01

    Interferometric techniques have proven useful to infer proximity and local surface profiles of microscopic objects near surfaces. But a critical trade-off emerges between accuracy and mathematical complexity when these methods are applied outside the vicinity of closest approach. Here we introduce a significant advancement that enables reflection interference contrast microscopy to provide nearly instantaneous reconstruction of an arbitrary convex object’s contour next to a bounding surface with nanometre resolution, making it possible to interrogate microparticle/surface interaction phenomena at radii of curvature 1,000 times smaller than those accessible by the conventional surface force apparatus. The unique view-from-below perspective of reflection interference contrast microscopy also reveals previously unseen deformations and allows the first direct observation of femtolitre-scale capillary condensation dynamics underneath micron-sized particles. Our implementation of reflection interference contrast microscopy provides a generally applicable nanometre-scale resolution tool that can be potentially exploited to dynamically probe ensembles of objects near surfaces so that statistical/probabilistic behaviour can be realistically captured. PMID:23715278

  20. A deployable telescope for sub-meter resolutions from microsatellite platforms

    Science.gov (United States)

    Dolkens, D.; Kuiper, J. M.

    2017-11-01

    Sub-meter resolution imagery has become increasingly important for disaster response, defence and security applications. Earth Observation (EO) at these resolutions has long been the realm of large and heavy telescopes, which results in high image costs, limited availability and long revisit times. Using synthetic aperture technology, instruments can now be developed that can reach these resolutions using a substantially smaller launch volume and mass. To obtain a competitive MicroSatellite telescope design, a concept study was performed to develop a deployable instrument that can reach a ground resolution of 25 cm from an orbital altitude of 500 km. Two classes of instruments were analysed: the Fizeau synthetic aperture, a telescope that uses a segmented primary mirror, and a Michelson synthetic aperture, an instrument concept that combines the light of a distributed array of afocal telescopes into a final image. In a trade-off the Fizeau synthetic aperture was selected as the most promising concept for obtaining high resolution imagery from a Low Earth Orbit. The optical design of the Fizeau synthetic aperture is based on a full-field Korsch telescope that has been optimized for compactness and an excellent wavefront quality. It uses three aperture segments in a tri-arm configuration that can be folded alongside the instrument during launch. The secondary mirror is mounted on a deployable boom, further decreasing the launch volume. To maintain a high image quality while operating in the harsh and dynamic space environment, one of the most challenging obstacles that must be addressed is the very tight tolerance on the positioning of the three primary mirror segments and the secondary mirror. Following a sensitivity analysis, systems engineering budgets have been defined. The instrument concept features a robust thermo-mechanical design, aimed at reducing the mechanical uncertainties to a minimum. Silicon Carbide mirror segments, the use of Invar for the deployable