Sample records for single-pass radar interferometer

  1. The Glacier and Ice Surface Topography Interferometer: UAVSAR's Single-pass Ka-Band Interferometer

    NASA Astrophysics Data System (ADS)

    Moller, D.; Hensley, S.; Sadowy, G.; Wu, X.; Carswell, J.; Fisher, C.; Michel, T.; Lou, Y.

    2012-12-01

    In May 2009 a new radar technique for mapping ice surface topography was demonstrated in a Greenland campaign as part of the NASA International Polar Year (IPY) activities. This was achieved with the airborne Glacier and Ice Surface Topography Interferometer (GLISTIN-A): a 35.6 GHz single-pass interferometer. Although the technique of using radar interferometry for mapping terrain has been demonstrated before, this is the first such application at millimeter-wave frequencies. The proof-of-concept demonstration was achieved by interfacing Ka-band RF and antenna hardware with the Uninhabited Airborne Vehicle Synthetic Aperture Radar (UAVSAR). The GLISTIN-A was implemented as a custom installation of the NASA Dryden Flight Research Center Gulfstream III. Instrument performance indicates swath widths over the ice between 5-7km, with height precisions ranging from 30cm-3m at a posting of 3m x 3m. Processing challenges were encountered in achieving the accuracy requirements on several fronts including, aircraft motion sensitivity, multipath and systematic drifts. However, through a combination of processor optimization, a modified phase-screen and motion-compensation implementations were able to minimize the impact of these systematic error sources. We will present results from the IPY data collections including system performance evaluations and imagery. This includes a large area digital elevation model (DEM) collected over Jakobshavn glacier as an illustrative science data product. Further, by intercomparison with the NASA Wallops Airborne Topographic Mapper (ATM) and calibration targets we quantify the interferometric penetration bias of the Ka-band returns into the snow cover. Following the success of the IPY campaign, we are funded under the Earth Science Techonology Office (ESTO) Airborne Innovative Technology Transition (AITT) program to transition GLISTIN-A to a permanently-available pod-only system compatible with unpressurized operation. In addition fundamental system upgrades will greatly enhance the performance and make wider-swath and higher altitude operation possible. We will show results from first flights of GLISTIN-A and summarize the plans for the near future including GLISTIN-H: GLISTIN on the NASA Global Hawk Spring 2013.

  2. An interferometer tracking radar system

    NASA Technical Reports Server (NTRS)

    Broderick, R. F.

    1969-01-01

    Fine tuning acquisition and tracking interferometer radar system uses a first antenna array of at least three receiving antennas. Array includes a reference antenna, a coarse tuning antenna, and a fine tuning antenna aligned on a receiving axis. Short range rendezvous system provides increased position accuracy.

  3. A microwave interferometer radar for spacecraft rendezvous missions

    Microsoft Academic Search

    Werner Koppl; Rusty Smith

    1986-01-01

    A microwave interferometer docking radar is described. This system employs a pulse radar to measure the relative angles between two spacecraft at close ranges. A phase interferometer is implemented to provide accurate measurements of the angular location of the target spacecraft. A preliminary design of an interferometer radar is performed to illustrate the advantages of this approach.

  4. VISAR: A Next Generation Inteferometric Radar for Venus Exploration

    NASA Astrophysics Data System (ADS)

    Hensley, S.; Smrekar, S.; Shaffer, S.; Paller, M.; Figueroa, H.; Freeman, A.; Hodges, R.; Walkemayer, P.

    2015-04-01

    The VERITAS Mission is a proposed mission to Venus designed to obtain high resolution imagery and topography of the surface using an X-band radar configured as a single pass radar interferometer coupled with a multispectral NIR mapping capability.

  5. Radar interferometer calibration of the EISCAT Svalbard Radar and a additional receiver station

    NASA Astrophysics Data System (ADS)

    Schlatter, N. M.; Grydeland, T.; Ivchenko, N.; Belyey, V.; Sullivan, J.; La Hoz, C.; Blixt, M.

    2013-12-01

    The EISCAT Svalbard Radar has two parabolic dishes. In order to attempt to implement radar aperture synthesis imaging methods three smaller, passive receive array antennas were built. Several science goals for this new receiver system exist, the primary of which is to study so called naturally enhanced ion acoustic lines. In order to compare radar aperture synthesis imaging results with measurements from optical imagers, calibration of the radar interferometer system is necessary. In this work we present the phase calibration of the EISCAT Svalbard interferometer including one array antenna. The calibration was done using the coherent scatter from satellites passing through the radar beam. Optical signatures of the satellite transits provide accurate position for the satellites. Using transits of a number of satellites sufficient for mapping the radar beam, the interferometric cross-phase was fitted within the radar beam. The calibration technique presented in this work will be applied to all antenna pairs of the antenna configuration for future interferometry studies.

  6. Comparison of New Mexico Tech VHF Interferometer and Arecibo radar data of lightning

    Microsoft Academic Search

    M. A. Stanley; V. P. Pasko; J. D. Mathews

    2001-01-01

    The New Mexico Tech InterferometerSferic (NMT INTF) system records both broadband electric field data and narrowband VHF phase and amplitude information at 274 MHz. Previous studies have shown that the NMT INTF system can identify and map most forms of slow and fast negative breakdown processes, but generally has difficulty detecting slow positive breakdown processes. The Arecibo Observatory UHF radar

  7. An Assessment of a Ka-Band Radar Interferometer Mission Accuracy Over Eurasian Rivers

    Microsoft Academic Search

    Vivien M. Enjolras; Ernesto Rodriguez

    2009-01-01

    The Water Elevation Recovery satellite mission is dedicated to the determination of land surface water extent, elevation, and slope using a Ka-band radar interferometer (KaRIn) as its primary instrument. Determining these parameters to the accuracy desired for hydrologic applications is challenging. The scientific objectives of the mission have been set up to 10 cm for the height budget and 10

  8. Single Pass Streaming BLAST on FPGAs*†

    PubMed Central

    Herbordt, Martin C.; Model, Josh; Sukhwani, Bharat; Gu, Yongfeng; VanCourt, Tom

    2008-01-01

    Approximate string matching is fundamental to bioinformatics and has been the subject of numerous FPGA acceleration studies. We address issues with respect to FPGA implementations of both BLAST- and dynamic-programming- (DP) based methods. Our primary contribution is a new algorithm for emulating the seeding and extension phases of BLAST. This operates in a single pass through a database at streaming rate, and with no preprocessing other than loading the query string. Moreover, it emulates parameters turned to maximum possible sensitivity with no slowdown. While current DP-based methods also operate at streaming rate, generating results can be cumbersome. We address this with a new structure for data extraction. We present results from several implementations showing order of magnitude acceleration over serial reference code. A simple extension assures compatibility with NCBI BLAST. PMID:19081828

  9. Multifrequency, single-pass free-electron laser. [Patent application

    SciTech Connect

    Szoke, A.; Prosnitz, D.

    1982-01-26

    A method for simultaneous amplification of laser beams with a sequence of freqeuncies in a single pass, using a relativistic beam of electrons grouped in a sequence of energies corresponding to the sequence of laser beam frequencies is described. The method allows electrons to pass from one potential well or bucket to another adjacent bucket, thus increasing efficiency of trapping and energy conversion.

  10. Single Pass Stripline Beam Position Monitor Design, Fabrication and Commissioning

    NASA Astrophysics Data System (ADS)

    Tan, Y.-R. E.; Wang, D.; Van Garderen, E.; McKinlay, J.

    2012-10-01

    To monitor the position of the electron beam during transport from the Booster Synchrotron to the Storage Ring at the Australian Synchrotron, a stripline Beam Position Monitor (BPM) has been designed, fabricated and installed in-house. The design was based on an existing stripline in the Booster and modified for the transfer line with a particular emphasis on ensuring the line impedance is properly matched to the detector system. The initial bench tests of a prototype stripline showed that the fabrication of the four individual striplines in the BPM was made precisely, each with a measured standing wave ratio (SWR) of 1.8 at 500 MHz. Further optimization for impedance matching will be done for new stripline BPMs. The linearity and gain factor was measured with the detector system. The detector system that digitizes the signals is an Instrumentation Technologies Brilliance Single Pass [1]. The results show an error of 1 mm at an offset (from the electrical centre) of 10 mm when a linear gain factor is assumed and an RMS noise of ~150 um that decreases to < 10 um with increasing signal intensity. The results were under our requirements for the transport line. The commissioning results of the stripline will also be presented showing a strong signal for an electron beam with an estimated integrated charge of ~50 nC with a position stability of 28 um (horizontal) and 75 um (vertical).

  11. Single-channel UWB SAR ground moving targets detection method using change detection based on single-pass sub-aperture images

    Microsoft Academic Search

    Zhou Hong; Huang Xiaotao; Chang Yulin; Zhou Zhimin

    2007-01-01

    Ultra-wide band synthetic aperture radar (UWB SAR) operating in VHF\\/UHF band has the capabilities in high resolution imaging and foliage penetration. In this paper we exploit its large beamwidth and propose a new ground moving target detection method for single-channel UWB SAR using change detection based on single-pass sub-aperture images, which is called sub-aperture SAR images change detection (SASICD). When

  12. The Shuttle Radar Topography Mission: A Global DEM

    NASA Technical Reports Server (NTRS)

    Farr, Tom G.; Kobrick, Mike

    2000-01-01

    Digital topographic data are critical for a variety of civilian, commercial, and military applications. Scientists use Digital Elevation Models (DEM) to map drainage patterns and ecosystems, and to monitor land surface changes over time. The mountain-building effects of tectonics and the climatic effects of erosion can also be modeled with DEW The data's military applications include mission planning and rehearsal, modeling and simulation. Commercial applications include determining locations for cellular phone towers, enhanced ground proximity warning systems for aircraft, and improved maps for backpackers. The Shuttle Radar Topography Mission (SRTM) (Fig. 1), is a cooperative project between NASA and the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense. The mission is designed to use a single-pass radar interferometer to produce a digital elevation model of the Earth's land surface between about 60 degrees north and south latitude. The DEM will have 30 m pixel spacing and about 15 m vertical errors.

  13. SHORT-WAVELENGTH, SINGLE-PASS FREE-ELECTRON LASERS J. Rossbach, DESY, 22603 Hamburg, Germany

    E-print Network

    SHORT-WAVELENGTH, SINGLE-PASS FREE-ELECTRON LASERS J. Rossbach, DESY, 22603 Hamburg, Germany in demonstration of high power gain at single- pass free-electron lasers operating in the wavelength range from in the undulator. Eq. (1) exhibits two main advantages of the free-electron laser: the free tunability

  14. Radar

    Microsoft Academic Search

    James R. Zimbelman; Kenneth S. Edgett

    1994-01-01

    Over 1,000,000 km2 of the equatorial surface of Mars west of the Arsia Mons volcano displays no 3.5-cm radar echo to the very low level of the radar system noise for the Very Large Array; the area displaying this unique property has been terms \\

  15. Observations of a rapidly flowing and significantly retreated Jakobshavn Isbrae and the proglacial ice mélange from a ground based radar interferometer

    NASA Astrophysics Data System (ADS)

    Cassotto, R. K.; Fahnestock, M. A.; Amundson, J. M.; Truffer, M.; de la Pena, S.; Joughin, I. R.

    2012-12-01

    Jakobshavn Isbrae has experienced several changes in seasonal behavior over the last decade. During the period of floating ice tongue loss and late summer grounded calving from 2000-2010, the calving front experienced a seasonally modulated ~5km advance and retreat as calving ceased during the winter and re-initiated in the spring. During that time the glacier doubled its speed and the terminus retreated ~14 km. The glacier entered a new seasonal pattern in 2010 when it continued to calve throughout the winter and subsequently failed to significantly re-advance. The glacier continues to evolve into 2012; it is now moving at a new maximum speed and the terminus has already reached a new minimum position in mid-summer, far earlier than in previous years. The calving style has changed from full glacier thick icebergs that calve as episodic events at one week to few week intervals to smaller sub-kilometer icebergs that calve more frequently. A two-week field campaign was conducted observing the terminus and proglacial ice mélange during in August 2012. A group of ground based radar interferometers were deployed to monitor changes in speed and surface deformation in response to calving events and tidal cycles, helping to illustrate the new style of calving, which leads to significantly smaller icebergs in the fjord. Observations are compared against GPS instruments deployed along the terminus as well as time-lapse photography and satellite data. The radars not only capture the motion of glacier ice, but are also well suited to document the response of the ice melange to calving events. The effects of atmospheric variability on ground based radar interferometry can be important.

  16. Single-Pass Online Learning: Performance, Voting Schemes and Online Feature Selection

    E-print Network

    Cohen, William W.

    Single-Pass Online Learning: Performance, Voting Schemes and Online Feature Selection Vitor R, it is essential to design inference and learning methods that operate in real time with limited memory. Online of averaging, a.k.a. vot- ing, on online learning. Finally, we describe how the new Modified Margin Balanced

  17. Fuel-element failures in Hanford single-pass reactors 1944--1971

    SciTech Connect

    Gydesen, S.P.

    1993-07-01

    The primary objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation dose that individuals could have received as a result of emissions since 1944 from the US Department of Energy`s (DOE) Hanford Site near Richland, Washington. To estimate the doses, the staff of the Source Terms Task use operating information from historical documents to approximate the radioactive emissions. One source of radioactive emissions to the Columbia River came from leaks in the aluminum cladding of the uranium metal fuel elements in single-pass reactors. The purpose of this letter report is to provide photocopies of the documents that recorded these failures. The data from these documents will be used by the Source Terms Task to determine the contribution of single-pass reactor fuel-element failures to the radioactivity of the reactor effluent from 1944 through 1971. Each referenced fuel-element failure occurring in the Hanford single-pass reactors is addressed. The first recorded failure was in 1948, the last in 1970. No records of fuel-element failures were found in documents prior to 1948. Data on the approximately 2000 failures which occurred during the 28 years (1944--1971) of Hanford single-pass reactor operations are provided in this report.

  18. Analysis of single pass ECH propagation and absorption experiments in MTX

    Microsoft Academic Search

    M. E. Fenstermacher; S. L. Allen; J. A. Byers; T. A. Casper; R. H. Cohen; J. H. Foote; E. B. Hooper; M. A. Makowski; W. H. Meyer; J. M. Moller; K. Oasa; T. Ogawa; B. W. Rice; T. D. Rognlien; G. R. Smith; B. W. Stallard; K. I. Thomassen; R. D. Wood

    1990-01-01

    Summary form only given. An experiment is being designed to measure the single-pass propagation and absorption of electron cyclotron heating (ECH) waves in dense plasmas and to compare the results with theoretical predictions. Calculations of microwave transmission through the MTX (Microwave Tokamak Experiment) access port, propagation of the waves through the plasma, and the resulting power deposition profile on a

  19. Observations of ice motion changes at the terminus of Hubbard Glacier using co-located ground-based radar interferometer and LiDAR scanning systems (Invited)

    NASA Astrophysics Data System (ADS)

    Wolken, G. J.; Finnegan, D. C.; Sharp, M. J.; LeWinter, A.; Fahnestock, M. A.; Stevens, R.

    2013-12-01

    The tidewater terminus of Hubbard Glacier extends into Disenchantment Bay and currently blocks most of the mouth of Russell Fjord. Recent advances of Hubbard Glacier (1986 and 2002) caused the damming of Russell Fjord, creating one of the largest glacier-dammed lakes on the continent and exposing the community of Yakutat to a host of potential hazards. Detailed observations of the terminus of Hubbard Glacier were conducted during a field campaign in May 2013. Ground-based radar interferometer (GBRI) and ground-based light detection and ranging (LiDAR) scanning systems were deployed to observe changes in ice motion in response to calving events and tidal cycles. GBRI and LiDAR units were co-located and data acquisition was synchronized to maximize data recovery and to aid inter-system comparisons. Observations from ground-based scanners were also compared to meteorological and tidal measurements and to time-lapse photography and satellite data. Both ground-based scanning systems capture ice motion at very high resolution, but each offer specific technical and logistical advantages. The combination of these ground-based remote sensing techniques allows us to quantify high-frequency changes in the velocity and surface deformation at the terminus of Hubbard Glacier and to develop a better understanding of the mechanisms associated with advancing tidewater termini.

  20. A constant-quality, single-pass VBR control for DVD recorders

    Microsoft Academic Search

    Daniele Bagni; Bruno Biffi; Rui Ramalho

    2003-01-01

    This paper describes a low complexity variable bit-rate (VBR) control method that achieves excellent and constant visual quality for single-pass, real time MPEG-2 encoding in DVD recorders. The bit-rate is controlled in a very accurate way. The algorithm runs in software on a very long instruction word (VLIW) processor by using less than 3 Millions of clock cycles.

  1. Eliminating cold-shut defects in deep, single-pass, electron beam welds in uranium

    Microsoft Academic Search

    D. H. Wood; G. L. Mara

    1977-01-01

    A technique for avoiding cold-shut defects in deep, single-pass, electron beam welds is described and evaluated. Shims of an appropriate alloying metal are interleaved in the joint before welding, and during the welding process the shim is melted and mixed into the weld metal, lowering the solidification temperature and thus preventing the formation of cold-shuts. For uranium and some of

  2. A Peltier cooled single pass amplifier for Titanium:Sapphire laser pulses

    Microsoft Academic Search

    A. Ozawa; W. Schneider; F. Najafi; T. W. Hänsch; Th. Udem; P. Hommelhoff

    2010-01-01

    We report on a Peltier cooled single pass amplifier for high repetition rate Titanium:sapphire laser pulses. Pumped with 14\\u000a W and seeded with around 400 mW, the output reaches 1.1 W with good beam quality. This amplifier is very user-friendly, easy\\u000a to maintain and set up and thus represents a device situated between more complicated liquid-nitrogen cooled amplifiers that\\u000a can

  3. Assessing the Efficacy of Single-Pass Backpack Electrofishing to Characterize Fish Community Structure

    Microsoft Academic Search

    Michael R. Meador; Julie P. McIntyre; Kenneth H. Pollock

    2003-01-01

    Two-pass backpack electrofishing data collected as part of the U.S. Geological Survey's National Water-Quality Assessment Program were analyzed to assess the efficacy of single-pass backpack electrofishing. A two-capture removal model was used to estimate, within 10 river basins across the United States, proportional fish species richness from one-pass electro- fishing and probabilities of detection for individual fish species. Mean estimated

  4. Assessing the Efficacy of Single-Pass Backpack Electrofishing to Characterize Fish Community Structure

    Microsoft Academic Search

    Michael R. Meador; Julie P. McIntyre; Kenneth H. Pollock

    2003-01-01

    Two-pass backpack electrofishing data collected as part of the U.S. Geological Survey's National Water-Quality Assessment Program were analyzed to assess the efficacy of single-pass backpack electrofishing. A two-capture removal model was used to estimate, within 10 river basins across the United States, proportional fish species richness from one-pass electrofishing and probabilities of detection for individual fish species. Mean estimated species

  5. Emittance Reduction between EBIS LINAC and Booster by Electron Beam Cooling; Is Single Pass Cooling Possible?

    SciTech Connect

    Hershcovitch,A.

    2008-04-01

    Electron beam cooling is examined as an option to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster. Electron beam parameters are based on experimental data (obtained at BNL) of electron beams extracted from a plasma cathode. Preliminary calculations indicate that single pass cooling is feasible; momentum spread can be reduced by more than an order of magnitude in less than one meter.

  6. KARIN: The Ka-Band Radar Interferometer for the Proposed Surface Water and Ocean Topography (SWOT) Mission

    NASA Technical Reports Server (NTRS)

    Esteban-Fernandez, Daniel; Peral, Eva; McWatters, Dalia; Pollard, Brian; Rodriguez, Ernesto; Hughes, Richard

    2013-01-01

    Over the last two decades, several nadir profiling radar altimeters have provided our first global look at the ocean basin-scale circulation and the ocean mesoscale at wavelengths longer than 100 km. Due to sampling limitations, nadir altimetry is unable to resolve the small wavelength ocean mesoscale and sub-mesoscale that are responsible for the vertical mixing of ocean heat and gases and the dissipation of kinetic energy from large to small scales. The proposed Surface Water and Ocean Topography (SWOT) mission would be a partnership between NASA, CNES (Centre National d'Etudes Spaciales) and the Canadian Space Agency, and would have as one of its main goals the measurement of ocean topography with kilometer-scale spatial resolution and centimeter scale accuracy. In this paper, we provide an overview of all ocean error sources that would contribute to the SWOT mission.

  7. Single-pass high-harmonic generation at 20.8 MHz repetition rate.

    PubMed

    Vernaleken, Andreas; Weitenberg, Johannes; Sartorius, Thomas; Russbueldt, Peter; Schneider, Waldemar; Stebbings, Sarah L; Kling, Matthias F; Hommelhoff, Peter; Hoffmann, Hans-Dieter; Poprawe, Reinhart; Krausz, Ferenc; Hänsch, Theodor W; Udem, Thomas

    2011-09-01

    We report on single-pass high-harmonic generation (HHG) with amplified driving laser pulses at a repetition rate of 20.8?MHz. An Yb:YAG Innoslab amplifier system provides 35?fs pulses with 20?W average power at 1030?nm after external pulse compression. Following tight focusing into a xenon gas jet, we observe the generation of high-harmonic radiation of up to the seventeenth order. Our results show that state-of-the-art amplifier systems have become a promising alternative to cavity-assisted HHG for applications that require high repetition rates, such as frequency comb spectroscopy in the extreme UV. PMID:21886233

  8. Measurement of gain and subband non-parabolicity in a ??10?m Quantum Cascade Laser from single-pass transmission measurements

    Microsoft Academic Search

    A. O. Dirisu; D. Revin; Zhijun Liu; K. Kennedy; J. Cockburn; C. Gmachl

    2008-01-01

    Sensitive single-pass transmission measurements for probing the electron distribution of Quantum Cascade lasers under an applied bias are used to extract the intersubband nonparabolicity and single-pass gain of a lambda~10 mum Quantum Cascade laser.

  9. Beam-Beam Simulations for a Single Pass SuperB-Factory

    SciTech Connect

    Biagini, M.E.; /Frascati; Raimondi, P.; Seeman, J.; /SLAC; Schulte, D.; /CERN

    2007-05-18

    A study of beam-beam collisions for an asymmetric single pass SuperB-Factory is presented [1]. In this scheme an e{sup -} and an e{sup +} beam are first stored and damped in two Damping Rings (DR), then extracted, compressed and focused to the IP. After collision the two beams are re-injected in the DR to be damped and extracted for collision again. The explored beam parameters are similar to those used in the design of the International Linear Collider, except for the beam energies. Flat beams and round beams were compared in the simulations in order to optimize both luminosity performances and beam blowup after collision. With such approach a luminosity of the order of 10{sup 36} cm{sup -2} s{sup -1} can be achieved.

  10. Single pass electron beam cooling of gold ions between EBIS LINAC and booster is theoretically possible!

    SciTech Connect

    Hershcovitch, A.

    2011-01-01

    Electron beam cooling is examined as an option to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster. Electron beam parameters are based on experimental data (obtained at BNL) of electron beams extracted from a plasma cathode. Many issues, regarding a low energy high current electron beam that is needed for electron beam cooling to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster, were examined. Computations and some experimental data indicate that none of these issues is a show stopper. Preliminary calculations indicate that single pass cooling is feasible; momentum spread can be reduced by more than an order of magnitude in about one meter. Hence, this option cooling deserves further more serious considerations.

  11. Development of a 2D Vlasov Solver for Single-Pass Systems

    SciTech Connect

    Venturini, Marco; Warnock, Robert; Zholents, Alexander

    2006-07-31

    Direct numerical methods for solving the Vlasov equationoffer some advantages over macroparticle simulations, as they do notsuffer from the numerical noise inherent in using a number ofmacroparticles smaller than the bunch population. Unfortunately thesemethods are more time-consuming and generally considered impractical in afull 6D phase space. However, in a lower-dimension phase space they maybecome attractive if the beam dynamics is sensitive to the presence ofsmall charge-density fluctuations and a high resolution is needed. Inthis paper we present a 2D Vlasov solver for studying the longitudinalbeam dynamics in single-pass systems of interest for X-FEL's, wherecharacterization of the microbunching instability is of particularrelevance. The solver includes a model to account for the smearing effectof a finite horizontal emittance on microbuncing. We explore the effectof space charge and coherent synchrotron radiation (CSR). The numericalsolutions are compared with results from linear theory and good agreementis found in the regime where linear theory applies.

  12. Parametric analysis of plastic strain and force distribution in single pass metal spinning

    NASA Astrophysics Data System (ADS)

    Choudhary, Shashank; Tejesh, Chiruvolu Mohan; Regalla, Srinivasa Prakash; Suresh, Kurra

    2013-12-01

    Metal spinning also known as spin forming is one of the sheet metal working processes by which an axis-symmetric part can be formed from a flat sheet metal blank. Parts are produced by pressing a blunt edged tool or roller on to the blank which in turn is mounted on a rotating mandrel. This paper discusses about the setting up a 3-D finite element simulation of single pass metal spinning in LS-Dyna. Four parameters were considered namely blank thickness, roller nose radius, feed ratio and mandrel speed and the variation in forces and plastic strain were analysed using the full-factorial design of experiments (DOE) method of simulation experiments. For some of these DOE runs, physical experiments on extra deep drawing (EDD) sheet metal were carried out using En31 tool on a lathe machine. Simulation results are able to predict the zone of unsafe thinning in the sheet and high forming forces that are hint to the necessity for less-expensive and semi-automated machine tools to help the household and small scale spinning workers widely prevalent in India.

  13. Part II/Addendum Electron Beam Cooling between EBIS LINAC and Booster; Is Single Pass Cooling Possible?

    SciTech Connect

    Hershcovitch,A.

    2008-07-01

    Due to some miscommunication, incomplete data was erroneously used in examining electron beam cooling for reducing momentum of gold ions exiting the EBIS LINAC before injection into the booster. Corrected calculations still indicate that single pass cooling is, in principle, feasible; momentum spread can be reduced by an order of magnitude in about one meter. Preliminary results suggest that this cooling deserves further consideration.

  14. Study on a test of optical stochastic cooling scheme in a single pass beam line

    SciTech Connect

    Chattopadhyay, S.; Kim, C.; Massoletti, D.; Zholents, A. [and others

    1997-01-01

    A feasibility study of an experiment to test the principle of optical stochastic cooling is presented. We propose to build a new beamline in the extraction area of the ALS Booster synchrotron, where we will include a bypass lattice similar to the lattice that could be used in the cooling insertion in a storage ring. Of course, in the single pass beamline we cannot achieve cooling, but we can test all the functions of the bypass lattice that are required to achieve cooling in a storage ring. As it is stated in, there are stringent requirements on the time-of-flight properties of the bypass lattice employed in a cooling scheme. The pathlengths of particle trajectories in the bypass must be fairly insensitive to the standard set of errors that usually affect the performance of storage rings. Namely, it is necessary to preserve all fluctuations in the longitudinal particle density within the beam from the beginning to the end of the bypass lattice with the accuracy of {lambda}/2{pi}, where A is the carrying (optical) wavelength. According to, cooling will completely vanish if a combined effect of all kinds of errors will produce a spread of the pathlengths of particle trajectories larger than {lambda}/2 and the cooling time will almost double if the spread of the pathlengths is {lambda}/2{pi}. At a first glance, {lambda}/2{pi} {approx_equal} 0.1/{mu}m is such a small value that satisfying this accuracy looks nearly impossible. However, simulations show that a carefully designed bypass can meet all the requirements even with rather conservative tolerance to errors.

  15. Single-pass continuous-flow leach test of PNL 76-68 glass: some selected Bead Leach I results

    Microsoft Academic Search

    Coles

    1981-01-01

    A single-pass continuous-flow leach test of PNL 76-68 glass beads (7 mm dia) was concluded after 420 days of uninterrupted operation. Variables included in the experimental matrix were flow-rate, leachant composition, and temperature. Analysis was conducted on all leachate samples for ²³⁷Np and ²³⁹Pu as well as a number of nonradioactive elements. Results indicated that flow-rate and leachant systematically affected

  16. Periodic step-size adaptation in second-order gradient descent for single-pass on-line structured learning

    Microsoft Academic Search

    Chun-nan Hsu; Han-shen Huang; Yu-ming Chang; Yuh-jye Lee

    2009-01-01

    Abstract It has been established that the second-order stochastic gradient descent (SGD) method,can potentially achieve generalization performance,as well as empirical optimum in a single pass through the training examples. However, second-order SGD requires com- puting the inverse of the Hessian matrix of the loss function, which is prohibitively expen- sive for structured prediction problems,that usually involve a very high dimensional,feature

  17. Phase-stable single-pass cryogenic amplifier for high repetition rate few-cycle laser pulses

    Microsoft Academic Search

    Akira Ozawa; Waldemar Schneider; Theodor W. Hänsch; Thomas Udem; Peter Hommelhoff

    2009-01-01

    We demonstrate cryogenic Ti:sapphire single-pass amplification of sub-7 fs laser pulses with 80 MHz repetition rate. We amplify the output of a broadband Ti:sapphire oscillator by more than a factor of two, re-compress the pulses down to sub-7 fs, and show that the rms carrier-envelope phase jitter stays below 70 as after amplification. The amplified output exceeds 2 MW of

  18. Constitutive cleavage of the single-pass transmembrane protein alcadein? prevents aberrant peripheral retention of Kinesin-1.

    PubMed

    Maruta, Chiaki; Saito, Yuhki; Hata, Saori; Gotoh, Naoya; Suzuki, Toshiharu; Yamamoto, Tohru

    2012-01-01

    Various membrane proteins are shed by proteinases, constitutively and/or when stimulated by external signals. While the physiological significance of external signal-induced cleavages has been intensely investigated, relatively little is known about the function of constitutive cleavages. Alcadein? (Alc?; also called Calsyntenin-1) is an evolutionarily conserved type I single-pass transmembrane protein that binds to kinesin-1 light chain (KLC) to activate kinesin-1's transport of Alc?-containing vesicles. We found that Alc? was constitutively and efficiently cleaved to liberate its ectodomain into the extracellular space, and that full-length Alc? protein was rarely detected on the cell surface. The secretion efficiency of the ectodomain was unaltered by a mutation that both abolished Alc?'s KLC-binding activity and attenuated its peripheral transport, suggesting that Alc?'s cleavage occurred, at least partly, en route to the cell surface. We further demonstrated that uncleavable mutant Alc? proteins readily accumulated on the cell surface and induced aberrant peripheral recruitment of KLC1 and kinesin heavy chain. Our observations suggest that Alc? is efficiently processed in part to minimize the inappropriate peripheral retention of kinesin-1. This role might exemplify the functional relevance of the constitutive cleavage of single-pass transmembrane proteins. PMID:22905201

  19. VLA/Goldstone (California) planetary radar results

    NASA Technical Reports Server (NTRS)

    Grossman, A. W.; Muhleman, D. O.; Slade, M. A.; Butler, B. J.

    1991-01-01

    Recent results from an entirely new technique of planetary radar astronomy are presented. The Very Large Array (VLA)/Goldstone planetary radar combines the transmitter of the Goldstone antenna and the receivers of the VLA interferometer to create a synthesis imaging radar instrument with unprecedented capabilities. The technique yields improved sensitivity and produces a direct sky map of radar flux density while avoiding the ambiguities associated with conventional range Doppler mapping. The method is illustrated by application to radar mapping of Mars and radar detection of Titan.

  20. Single-pass continuous-flow leach test of PNL 76-68 glass: some selected Bead Leach I results

    SciTech Connect

    Coles, D.G.

    1981-08-20

    A single-pass continuous-flow leach test of PNL 76-68 glass beads (7 mm dia) was concluded after 420 days of uninterrupted operation. Variables included in the experimental matrix were flow-rate, leachant composition, and temperature. Analysis was conducted on all leachate samples for /sup 237/Np and /sup 239/Pu as well as a number of nonradioactive elements. Results indicated that flow-rate and leachant systematically affected the leach rate, but only slightly. Temperature effects were significant. Plutonium leach rate was lower at higher temperature suggesting that Pu sorption onto the beads was enhanced at the higher temperature. The range of leach rates for all analyzed elements (except Pu), at both temperatures, at all three flow rates, and with all three leachant compositions varied over only three orders of magnitude. The range of variables used in this experiment covered those expected in many proposed repository environments.

  1. Velocity-resolved 3D retinal microvessel imaging using single-pass flow imaging spectral domain optical coherence tomography?

    PubMed Central

    Tao, Yuankai K.; Kennedy, Kristen M.; Izatt, Joseph A.

    2009-01-01

    We demonstrate in vivo velocity-resolved, volumetric bidirectional blood flow imaging in human retina using single-pass flow imaging spectral domain optical coherence tomography (SPFI-SDOCT). This technique uses previously described methods for separating moving and non-moving scatterers within a depth by using a modified Hilbert transform. Additionally, a moving spatial frequency window is applied, creating a stack of depth-resolved images of moving scatterers, each representing a finite velocity range. The resulting velocity reconstruction is validated with and strongly correlated to velocities measured with conventional Doppler OCT in flow phantoms. In vivo velocity-resolved flow mapping is acquired in healthy human retina and demonstrate the measurement of vessel size, peak velocity, and total foveal blood flow with OCT. PMID:19259254

  2. Atom Interferometers

    E-print Network

    Alexander D. Cronin; Joerg Schmiedmayer; David E. Pritchard

    2007-12-21

    Interference with atomic and molecular matter waves is a rich branch of atomic physics and quantum optics. It started with atom diffraction from crystal surfaces and the separated oscillatory fields technique used in atomic clocks. Atom interferometry is now reaching maturity as a powerful art with many applications in modern science. In this review we first describe the basic tools for coherent atom optics including diffraction by nanostructures and laser light, three-grating interferometers, and double wells on AtomChips. Then we review scientific advances in a broad range of fields that have resulted from the application of atom interferometers. These are grouped in three categories: (1) fundamental quantum science, (2) precision metrology and (3) atomic and molecular physics. Although some experiments with Bose Einstein condensates are included, the focus of the review is on linear matter wave optics, i.e. phenomena where each single atom interferes with itself.

  3. Single-pass continuous-flow leach test of PNL 76-68 glass: some selected Bead Leach I results

    SciTech Connect

    Coles, D.G.

    1981-01-22

    A single-pass continuous-flow leach test of PNL 76-68 glass beads (7 mm dia) was concluded after 420 days of uninterrupted operation. Variables included in the experimental matrix were flow-rate, leachant composition, and temperature. Analysis was conducted on all leachate samples for /sup 237/Np and /sup 239/Pu as well as a number of nonradioactive elements. Results indicated that flow-rate and leachant systematically affected the leach rate, but only slightly. Temperature effects were significant. Plutonium leach rate was lower at higher temperature suggesting that Pu sorption onto the beads was enhanced at the higher temperature. The range of leach rates for all analyzed elements (except Pu), at both temperature, at all three flow rates, and with all three leachant compositions varied only three orders of magnitude. The range of variables used in this experiment covered those expected in many proposed repository environments. The preliminary interpretation of the results also indicated that matrix dissolution may be the dominant leaching mechanism, at least for Np in bicarbonate leachant. Regardless of the leaching mechanism the importance of this study is that it bounds the effects of repository environments when the ground water is oxidizing and when it doesn't reach the waste form until the waste has cooled to ambient rock temperature.

  4. Single-Pass Percutaneous Liver Biopsy for Diffuse Liver Disease Using an Automated Device: Experience in 154 Procedures

    SciTech Connect

    Rivera-Sanfeliz, Gerant, E-mail: gerantrivera@ucsd.edu; Kinney, Thomas B.; Rose, Steven C.; Agha, Ayad K.M.; Valji, Karim; Miller, Franklin J.; Roberts, Anne C. [UCSD Medical Center, Department of Radiology (United States)

    2005-06-15

    Purpose: To describe our experience with ultrasound (US)-guided percutaneous liver biopsies using the INRAD 18G Express core needle biopsy system.Methods: One hundred and fifty-four consecutive percutaneous core liver biopsy procedures were performed in 153 men in a single institution over 37 months. The medical charts, pathology reports, and radiology files were retrospectively reviewed. The number of needle passes, type of guidance, change in hematocrit level, and adequacy of specimens for histologic analysis were evaluated.Results: All biopsies were performed for histologic staging of chronic liver diseases. The majority of patients had hepatitis C (134/153, 90.2%). All patients were discharged to home after 4 hr of postprocedural observation. In 145 of 154 (94%) biopsies, a single needle pass was sufficient for diagnosis. US guidance was utilized in all but one of the procedures (153/154, 99.4%). The mean hematocrit decrease was 1.2% (44.1-42.9%). Pain requiring narcotic analgesia, the most frequent complication, occurred in 28 of 154 procedures (18.2%). No major complications occurred. The specimens were diagnostic in 152 of 154 procedures (98.7%).Conclusions: Single-pass percutaneous US-guided liver biopsy with the INRAD 18G Express core needle biopsy system is safe and provides definitive pathologic diagnosis of chronic liver disease. It can be performed on an outpatient basis. Routine post-biopsy monitoring of hematocrit level in stable, asymptomatic patients is probably not warranted.

  5. Development of a 2D Vlasov Solver for Longitudinal BeamDynamics in Single-Pass Systems

    SciTech Connect

    Venturini, M.; Warnock, R.; Zholents, A.; /SLAC

    2006-12-12

    Direct numerical methods for solving the Vlasov equation offer some advantages over macroparticle simulations, as they do not suffer from the numerical noise inherent in using a number of macroparticles smaller than the bunch population. Unfortunately these methods are more time-consuming and generally considered impractical in a full 6D phase space. However, in a lower-dimension phase space they may become attractive if the beam dynamics is sensitive to the presence of small charge-density fluctuations and a high resolution is needed. In this paper we present a 2D Vlasov solver for studying the longitudinal beam dynamics in single-pass systems of interest for X-FEL's, where characterization of the microbunching instability is of particular relevance. The solver includes a model to account for the smearing effect of a finite horizontal emittance on microbunching. We explore the effect of space charge and coherent synchrotron radiation (CSR). The numerical solutions are compared with results from linear theory and good agreement is found in the regime where linear theory applies.

  6. Profile and depth prediction in single-pass and two-pass CO2 laser microchanneling processes

    NASA Astrophysics Data System (ADS)

    Prakash, Shashi; Kumar, Subrata

    2015-03-01

    Polymer based microfluidic channels are used in many chemical and biological devices. Polymethylmethacrylate (PMMA) has emerged as a key material for such devices owing to its high optical transparency and mechanical strength. The use of CO2 laser processing for fabricating microchannels on PMMA has been proved as an efficient and cost effective method. In this work, theoretical models for predicting microchannel profile and depth have been proposed. A model for single-pass laser processing has been proposed based on energy balance. A two-pass laser process for microchannel fabrication produces smoother microchannels with better surface topography and reduced bulging around the microchannel edges. An energy balance based model has also been proposed for two-pass processing. The experimental verification of the proposed models was conducted. Spectroscopic tests were carried out to determine the absorptivity, and simultaneous thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) tests were performed to determine the thermo-physical properties of the PMMA used in the proposed model. The results predicted using the model were found to be in close agreement with the actual values.

  7. Experimental validation of single pass ion cyclotron resonance absorption in a high speed flowing plasma applied to the variable specific impulse magnetoplasma rocket (VASIMR)

    Microsoft Academic Search

    Christopher Nelson Davis

    2006-01-01

    The topic of this thesis is the experimental characterization and analysis of single pass ion cyclotron resonance heating as applied to acceleration of ions for electric propulsion. The experimental work was done on the VX-10 experiment of the VASIMR (Variable Specific Impulse Magnetoplasma Rocket) concept. In ion cyclotron resonance heating (ICRH) a RF wave is launched into a magnetized plasma

  8. January 1, 1999 / Vol. 24, No. 1 / OPTICS LETTERS 61 Single-pass measurements of the wave-front aberrations of the

    E-print Network

    Dainty, Chris

    for the left eye of subject LD, aged 26 years and with em- metropic eyes. The retina was illuminated by light-front aberrations of the human eye by use of retinal lipofuscin autofluorescence L. Diaz Santana Haro and J. C a technique for making single-pass measurements of the wave-front aberration of the eye. The technique

  9. Dissolution Kinetics of Titanium Pyrochlore Ceramics at 90?C by Single-Pass Flow-Through Experiments

    SciTech Connect

    Icenhower, Jonathan P.; McGrail, B. Peter; Schaef, Herbert T.; Cordova, Elsa A.

    2000-12-01

    Corrosion resistances of titanium-based ceramics are quantified using single-pass flow-through (SPFT) experiments. The materials tested include simple pyrochlore group (B2Ti2O7, where B=Lu^3+ or Gd^3+) and complex multiphase materials that are either pyrochlore- (PY12) or zirconolite-dominated (BSL3). Experiments are conducted at 90?C over a range of pH-buffered conditions with typical duration of experiments in excess of 120 days. Apparent steady-state dissolution rates at pH=2 determined on the Gd2Ti2O7 and Lu2Ti2O7 samples indicate congruent dissolution, with rates of the former (1.3x10^-3 to 4.3x10^-3) slightly faster than the latter (4.4x10^-4 to 7.0x10^-4 g m^-2 d^-1). Rates for PY12 materials into pH=2 solutions are 5.9x10^-5 to 8.6x10^-5 g m^-2 d^-1. In contrast, experiments with BSL3 material do not reach steady-state conditions, and appear to undergo rapid physical and chemical corrosion into solution. At faster flow-through rates, dissolution rates display a shallow amphoteric behavior, with a minimum (4.6x10^-5 to 5.8x10^-5 g m^-2 d^-1) near pH values of 7. Dissolution rates display a measurable increase (~10X) with increasing flow-through rate indicating the strong influence that chemical affinity asserts on the system. These results step towards an evaluation of the corrosion mechanism and an evaluation of the long-term performance of Pu-bearing titanite engineered materials in the subsurface.

  10. Interferometer for measuring displacement and distance

    Microsoft Academic Search

    Toshihiro Kubota; Makoto Nara; Toshihiko Yoshino

    1987-01-01

    A simple interferometer for measuring both relative displacement and absolute distance is fabricated that uses a laser diode. The sign of the displacementis detected by means of a lambda\\/8 plate, and the distance is measured by an FM radar technique of modulating the laser-diode frequency. Measurement accuracies of 0.02 micron for displacement and 100 microns for distance are obtained over

  11. Experimental investigation of high-power single-pass Raman shifters in the ultraviolet with Nd:YAG and KrF lasers

    Microsoft Academic Search

    Laurent de Schoulepnikoff; Valentin Mitev; Valentin Simeonov; Bertrand Calpini; Hubert van den Bergh

    1997-01-01

    Single-pass Raman cells pumped by either a quadrupled Nd:YAG (266-nm) laser or a KrF excimer laser are studied. The Raman-active gases comprise H 2 , D 2 , or CH 4 , as well as a mixture of them, with the addition of He, Ne, or Ar. A parametric study, in which the Stokes conversion efficiency and the beam quality

  12. Evaluation of the Long-Term Performance of Titanate Ceramics for Immobilization of Excess Weapons Plutonium: Results from Pressurized Unsaturated Flow and Single Pass Flow-Through Testing

    Microsoft Academic Search

    BP McGrail; HT Schaef; JP Icenhower; PF Martin; VL Legore

    1999-01-01

    This report summarizes our findings from pressurized unsaturated flow (PUF) and single-pass flow-through (SPFT) experiments to date. Results from the PUF test of a Pu-bearing ceramic with enclosing surrogate high-level waste glass show that the glass reacts rapidly to alteration products. Glass reaction causes variations in the solution pH in contact with the ceramic materials. We also document variable concentrations

  13. Special relativity and interferometers

    NASA Technical Reports Server (NTRS)

    Han, D.; Kim, Y. S.

    1988-01-01

    A new generation of gravitational wave detectors is expected to be based on interferometers. Yurke et al. (1986) introduced a class of interferometers characterized by SU(1,1) which can in principle achieve a phase sensitivity approaching 1/N, where N is thte total number of photons entering the interferometer. It is shown here that the SU(1,1) interferometer can serve as an analog computer for Wigner's little group of the Poincare\\'| group.

  14. Deployment of the Polar Atmospheric Emitted Radiance Interferometer (P-AERI) in Eureka, Canada for SEARCH

    E-print Network

    Walden, Von P.

    Deployment of the Polar Atmospheric Emitted Radiance Interferometer (P-AERI) in Eureka, Canada Interferometer (P-AERI) is an important instrument for Arctic research and for monitoring downwelling spectral Resolution Lidar (AHSRL) ­ SSEC, U. Wisconsin; Millimeter Cloud Radar ­ NOAA, Microwave Radiometer ­ NOAA

  15. Combined Twyman-Green and Mach-Zehnder interferometer for microlens testing

    NASA Astrophysics Data System (ADS)

    Reichelt, Stephan; Zappe, Hans

    2005-09-01

    A new interferometer design for microlens testing is presented. The phase-shifting system combines the advantages of a Twyman-Green and a Mach-Zehnder interferometer and permits full characterization of the aberrations of microlenses as well as radius of curvature and focal length measurements. The Twyman-Green system is applied to surface testing in reflection (single reflection), whereas the Mach-Zehnder system is used for lens testing in transmission (single pass). Both measurements are performed without removal of the test part, allowing for combination of the results without confusion of the actual lens and without an azimuthal orientation error. The interferometer setup is explained, the test procedure is described, and experimental results are given.

  16. A High Speed Microwave Interferometer used for Monitoring Stromboli Volcano

    Microsoft Academic Search

    Linhsia Noferini; Daniele Mecatti; Giovanni Macaluso; Massimiliano Pieraccini; Carlo Atzeni; Maurizio Ripepe

    2009-01-01

    This work reports on the results obtained with a high speed ground based radar interferometer applied to the monitoring of the explosive activity of Stromboli volcano, Italy. The sensor illuminated a few craters below the summit distinguishing among them according to their distances from the sensor. The sampling rate allowed tracking the craters' movements even while they were erupting providing

  17. Phase shifting interferometer

    DOEpatents

    Sommargren, Gary E. (Santa Cruz, CA)

    1999-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. Whereas current interferometers illuminate the optic to be tested with an aberrated wavefront which also limits the accuracy of the measurement, this interferometer uses an essentially perfect spherical measurement wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  18. High sensitivity two-frequency paired polarized interferometer in Faraday rotation angle measurement of ambient air with single-traveling configuration

    Microsoft Academic Search

    Chu-En Lin; Chih-Jen Yu; Ying-Chang Li; Chien-Chung Tsai; Chien Chou

    2008-01-01

    High sensitivity detection on Faraday rotation and Verdet constant of ambient air under weak applied magnet field and single-pass configuration specimen is setup in which a two-frequency paired linear polarized interferometer (TPPI) coupled with balanced detector shown at shot-noise-limited detection is demonstrated. The Verdet constant of ambient air at 1.3×10-6 rad\\/mT m and its sensitivity at 4.3×10-8 rad\\/mT m were

  19. Radar Entomology

    NSDL National Science Digital Library

    0000-00-00

    Radar tracking used to profile insect migration, mating and flight patterns. Many links to various pages include current workers in radar entomology, historical uses of the technology, and many images.

  20. Radar principles

    NASA Technical Reports Server (NTRS)

    Sato, Toru

    1989-01-01

    Discussed here is a kind of radar called atmospheric radar, which has as its target clear air echoes from the earth's atmosphere produced by fluctuations of the atmospheric index of refraction. Topics reviewed include the vertical structure of the atmosphere, the radio refractive index and its fluctuations, the radar equation (a relation between transmitted and received power), radar equations for distributed targets and spectral echoes, near field correction, pulsed waveforms, the Doppler principle, and velocity field measurements.

  1. Meteor wind observations with the MU radar

    Microsoft Academic Search

    T. Nakamura; M. Tsutsumi; T. Uehara; S. Fukao; S. Kato

    1991-01-01

    Meteor wind observations were conducted with the middle and upper atmosphere (MU) radar at Shigaraki, Japan (35 deg N, 136 deg E), utilizing an interferometer to determine the arrival angle of a meteor echo. Meteor echoes are widely distributed in zenith angles as large as 50 deg and the narrow main lobe of a transmitting antenna cannot effectively detect meteor

  2. High-Repetition-Rate, Single-Pass Third-Harmonic Generation of 354 nm Ultraviolet Laser with 51.5% Efficiency

    NASA Astrophysics Data System (ADS)

    Chen, Hailong; Liu, Qiang; Yan, Ping; Xiao, Qirong; Gong, Mali

    2012-09-01

    At a high repetition rate of 1 MHz, the maximum 32.1 W TEM00 mode ultraviolet (UV) laser is generated by harmonically converting the output of semiconductor-diode-seeded four-cascaded fiber amplifiers. The master-oscillator-fiber-power-amplifier (fiber-MOPA) configuration based IR source exhibits high power with excellent spatial, temporal, spectral, and polarizing performances. The novel single-pass frequency tripling scheme, beginning with the noncritical phase matching (PM) for second-harmonic generation and the subsequent noncollinear PM for third-harmonic generation, is used to minimize the spatial walk-off effect. Due to the overall system optimization, the optic-optic conversion efficiency from IR to UV is scaled up to 51.5%.

  3. Single-pass Kelvin force microscopy and dC/dZ measurements in the intermittent contact: applications to polymer materials

    PubMed Central

    Alexander, John

    2011-01-01

    Summary We demonstrate that single-pass Kelvin force microscopy (KFM) and capacitance gradient (dC/dZ) measurements with force gradient detection of tip–sample electrostatic interactions can be performed in the intermittent contact regime in different environments. Such combination provides sensitive detection of the surface potential and capacitance gradient with nanometer-scale spatial resolution as it was verified on self-assemblies of fluoroalkanes and a metal alloy. The KFM and dC/dZ applications to several heterogeneous polymer materials demonstrate the compositional mapping of these samples in dry and humid air as well as in organic vapors. In situ imaging in different environments facilitates recognition of the constituents of multi-component polymer systems due to selective swelling of components. PMID:21977411

  4. Sub-Aperture Interferometers

    NASA Technical Reports Server (NTRS)

    Zhao, Feng

    2010-01-01

    Sub-aperture interferometers -- also called wavefront-split interferometers -- have been developed for simultaneously measuring displacements of multiple targets. The terms "sub-aperture" and "wavefront-split" signify that the original measurement light beam in an interferometer is split into multiple sub-beams derived from non-overlapping portions of the original measurement-beam aperture. Each measurement sub-beam is aimed at a retroreflector mounted on one of the targets. The splitting of the measurement beam is accomplished by use of truncated mirrors and masks, as shown in the example below

  5. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, Gary E. (Santa Cruz, CA)

    1996-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  6. Fizeau plasma interferometer

    SciTech Connect

    Frank, A.M.

    1980-01-01

    This paper describes a technique by which the sensitivity of plasma interferometers can be increased. Stabilization and fractional fringe measurement techniques have improved to the point where additional optical sensitivity could be useful. (MOW)

  7. Dual surface interferometer

    DOEpatents

    Pardue, Robert M. (Knoxville, TN); Williams, Richard R. (Oak Ridge, TN)

    1982-01-01

    A double-pass interferometer is provided which allows direct measurement of relative displacement between opposed surfaces. A conventional plane mirror interferometer may be modified by replacing the beam-measuring path cube-corner reflector with an additional quarter-wave plate. The beam path is altered to extend to an opposed plane mirrored surface and the reflected beam is placed in interference with a retained reference beam split from dual-beam source and retroreflected by a reference cube-corner reflector mounted stationary with the interferometer housing. This permits direct measurement of opposed mirror surfaces by laser interferometry while doubling the resolution as with a conventional double-pass plane mirror laser interferometer system.

  8. Dual surface interferometer

    DOEpatents

    Pardue, R.M.; Williams, R.R.

    1980-09-12

    A double-pass interferometer is provided which allows direct measurement of relative displacement between opposed surfaces. A conventional plane mirror interferometer may be modified by replacing the beam-measuring path cube-corner reflector with an additional quarterwave plate. The beam path is altered to extend to an opposed plane mirrored surface and the reflected beam is placed in interference with a retained reference beam split from dual-beam source and retroreflected by a reference cube-corner reflector mounted stationary with the interferometer housing. This permits direct measurement of opposed mirror surfaces by laser interferometry while doubling the resolution as with a conventional double-pass plane mirror laser interferometer system.

  9. X-ray crystal interferometers

    NASA Astrophysics Data System (ADS)

    Lider, V. V.

    2014-11-01

    Various configurations of the X-ray crystal interferometer are reviewed. The interferometer applications considered include metrology, the measurement of fundamental physical constants, the study of weakly absorbing phase objects, time-resolved diagnostics, the determination of hard X-ray beam parameters, and the characterization of structural defects in the context of developing an X-ray Michelson interferometer. The three-crystal Laue interferometer (LLL-interferometer), its design, and the experimental opportunities it offers are given particular attention.

  10. SRTM X-SAR motion compensation: concept and first assessment of the interferometric observation geometry

    Microsoft Academic Search

    Nico Adam; Michael Eineder; Helko Breit

    2001-01-01

    The space shuttle Endeavour that flew from 11 until 22 February carried the radar systems for the Shuttle Radar Topography Mission (SRTM). In the course of this project the first space born single pass interferometer has mapped the Earth's topography. Two different radar systems operated on board of the space shuttle: the C-band radar of the American NASA\\/JPL and the

  11. Spaceborne radar

    NASA Technical Reports Server (NTRS)

    Moore, R. K.; Eckerman, J.; Meneghini, R.; Atlas, D.; Boerner, W. M.; Cherry, S.; Clark, J. F.; Doviak, R. J.; Goldhirsh, J.; Lhermitte, R. M.

    1981-01-01

    The spaceborne radar panel considered how radar could be used to measure precipitation from satellites. The emphasis was on how radar could be used with radiometry (at microwave, visible (VIS), and infrared (IR) wavelengths) to reduce the uncertainties of measuring precipitation with radiometry alone. In addition, the fundamental electromagnetic interactions involved in the measurements were discussed to determine the key work areas for research and development to produce effective instruments. Various approaches to implementing radar systems on satellites were considered for both shared and dedicated instruments. Finally, a research and development strategy was proposed for establishing the parametric relations and retrieval algorithms required for extracting precipitation information from the radar and associated radiometric data.

  12. PDX multichannel interferometer

    SciTech Connect

    Bitzer, R.; Ernst, W.; Cutsogeorge, G.

    1980-10-01

    A 10 channel, 140 GHz homodyne interferometer is described for use on PDX. One feature of this interferometer is the separation of the signal source and electronics from the power splitters, delay line, and receiving systems. The latter is situated near the upper and lower vacuum ports between the toroidal field magnets. A second feature is the signal stabilization of the EIO source by means of an AFC system. The complete interferometer is described including block diagrams, circuit diagrams, test data, and magnetic field test conducted on the preamplifiers, microwave diodes, isolators, etc., to determine the extent of magnetic shielding required. The description of the tracking filters and digital phase display circuit is referenced to accompanying reports.

  13. A microwave interferometer with imaging capability for remote measurements of building displacements

    Microsoft Academic Search

    M. Pieraccini; G. Luzi; D. Mecatti; L. Carissimi; G. Franchioni; C. Atzeni

    2005-01-01

    In this paper the authors report some experimental activities carried out in Italy during the last few years, aimed at verifying\\u000a the effectiveness of the use of coherent radar imaging to retrieve information on buildings deformations. Maps of differential\\u000a phase obtained by means of a microwave interferometer with imaging capabilities are presented. Images were obtained by a synthetic-aperture\\u000a interferometric radar

  14. Comparison of the results of short-term static tests and single-pass flow-through tests with LRM glass.

    SciTech Connect

    Ebert, W. L.; Chemical Engineering

    2007-01-29

    Static dissolution tests were conducted to measure the forward dissolution rate of LRM glass at 70 C and pH(RT) 11.7 {+-} 0.1 for comparison with the rate measured with single-pass flow-through (SPFT) tests in an interlaboratory study (ILS). The static tests were conducted with monolithic specimens having known geometric surface areas, whereas the SPFT tests were conducted with crushed glass that had an uncertain specific surface area. The error in the specific surface area of the crushed glass used in the SPFT tests, which was calculated by modeling the particles as spheres, was assessed based on the difference in the forward dissolution rates measured with the two test methods. Three series of static tests were conducted at 70 C following ASTM standard test method C1220 using specimens with surfaces polished to 600, 800, and 1200 grit and a leachant solution having the same composition as that used in the ILS. Regression of the combined results of the static tests to the affinity-based glass dissolution model gives a forward rate of 1.67 g/(m{sup 2}d). The mean value of the forward rate from the SPFT tests was 1.64 g/(m{sup 2}d) with an extended uncertainty of 1.90 g/(m{sup 2}d). This indicates that the calculated surface area for the crushed glass used in the SPFT tests is less than 2% higher than the actual surface area, which is well within the experimental uncertainties of measuring the forward dissolution rate using each test method. These results indicate that the geometric surface area of crushed glass calculated based on the size of the sieves used to isolate the fraction used in a test is reliable. In addition, the C1220 test method provides a means for measuring the forward dissolution rate of borosilicate glasses that is faster, easier, and more economical than the SPFT test method.

  15. Accuracy and resolution of shuttle radar topography mission data Bridget Smith and David Sandwell

    E-print Network

    Sandwell, David T.

    ascending and descending C-band swaths from the Shuttle interferometer were processed into a digitalAccuracy and resolution of shuttle radar topography mission data Bridget Smith and David Sandwell provided by the Shuttle Radar Topography Mission (SRTM) through spectral comparisons with the National

  16. Radar interferometry: A new technique for studying plasma turbulence in the ionosphere

    Microsoft Academic Search

    D.T. Farley; H.M. Ierkic; B.G. Fejer

    1981-01-01

    A new radar interferometer technique has been developed and used successfully at the Jicamarca Radio Observatory in Peru to study the strong nighttime plasma turbulence in the equatorial electrojet. The technique represents a major step forward in radar probing of turbulent irregularities such as (but not limited to) those in the electrojet. In many situations it provides far more information

  17. Multispectral infrared imaging interferometer

    NASA Technical Reports Server (NTRS)

    Potter, A. E., Jr.

    1971-01-01

    Device permitting simultaneous viewing of infrared images at different wavelengths consists of imaging lens, Michelson interferometer, array of infrared detectors, data processing equipment for Fourier transformation of detector signal, and image display unit. Invention is useful in earth resources applications, nondestructive testing, and medical diagnoses.

  18. Ultrasonic Interferometers Revisited

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2007-01-01

    I have been tinkering with ultrasonic transducers once more. In earlier notes I reported on optics-like experiments performed with ultrasonics, described a number of ultrasonic interferometers, and showed how ultrasonic transducers can be used for Fourier analysis. This time I became interested in trying the technique of using two detectors in…

  19. Digital elevation models of the Moon from Earth-based radar interferometry

    Microsoft Academic Search

    Jean-Luc Margot; Donald B. Campbell; Raymond F. Jurgens; Martin A. Slade

    2000-01-01

    Three-dimensional (3D) maps of the nearside and polar regions of the Moon can be obtained with an Earth-based radar interferometer. This paper describes the theoretical background, experimental setup, and processing techniques for a sequence of observations performed with the Goldstone Solar System Radar in 1997. These data provide radar imagery and digital elevation models of the polar areas and other

  20. Imaging system for low-density plasma by heterodyne interferometer with fan beam microwave

    Microsoft Academic Search

    H. Ito; N. Yugami; Y. Nishida; W. Sakai

    2002-01-01

    A microwave imaging system based on a heterodyne interferometer has been developed to measure the spatial distribution of the plasma density without introducing any direct disturbance to the plasma by employing a diode array scattering technique. The imaging system with the use of a fan beam microwave for a radar system demonstrates the principle of the technique by placing finite-size

  1. Visible nulling interferometer

    NASA Technical Reports Server (NTRS)

    Shao, M.; Serabyn, E.; Martin, B. M.; Mennesson, B.; Velusamy, T.

    2002-01-01

    The direct detection of Earthlike planets in the visible is a very challenging goal. This paper describes a new concept for visible direct detection of Earths using a nulling interferometer instrument behind a 4m telescope in space. The basic concept is described along with the key advantages of the nulling interferometer over more traditional approaches, an apodized aperture telescope or coronagraph. In the baseline design, a 4 beam nuller produces a very deep theta^4 null. With perfect optics, the stellar leakage is less than le-11 of the starlight at the location of the planet. With diffraction limited (lambda/20) telescope optics suppression of the starlight to -1e-10 would be possible.

  2. Correlation interferometer geolocation

    Microsoft Academic Search

    Keith Struckman; Nashua NH

    2006-01-01

    Geolocation solutions based on the correlation interferometer geolocation (CIGL) equation depend on searching over (xi,y i) space and identifying the transmitter location as the (x,y) value that maximizes the correlation value. Under cross-polarized incident field conditions this correlation depends on both the array manifold calibration polarization and the targets transmission polarization. Computation of the transmitted polarization is accomplished by maximizing

  3. Directional borehole radar with dipole antenna array using optical modulators

    Microsoft Academic Search

    Satoshi Ebihara

    2004-01-01

    In this paper, we describe a directional borehole radar comprising a dipole antenna array with an optical modulator capable of determining the position of targets in three dimensions (3-D). Optical modulators using a Mach-Zehnder interferometer are used to transform electrical signals into optical signals at the feeding points of the dipole antennas. The advantages of using these modulators are that

  4. Nonlinear microwave spin wave interferometer

    Microsoft Academic Search

    A. B. Ustinov; B. A. Kalinikos

    2001-01-01

    The characteristics of a nonlinear microwave spin wave interferometer were experimentally studied for the first time. The\\u000a interferometer was implemented according to a bridge scheme with a nonlinear spin wave phase shifter based on an yttrium-iron\\u000a garnet film. The maximum sensitivity of the nonlinear interferometer with respect to the input signal level was reached with\\u000a a phase shifter operating on

  5. Evaluation of the Long-Term Performance of Titanate Ceramics for Immobilization of Excess Weapons Plutonium: Results from Pressurized Unsaturated Flow and Single Pass Flow-Through Testing

    SciTech Connect

    BP McGrail; HT Schaef; JP Icenhower; PF Martin; RD Orr; VL Legore

    1999-09-13

    This report summarizes our findings from pressurized unsaturated flow (PUF) and single-pass flow-through (SPFT) experiments to date. Results from the PUF test of a Pu-bearing ceramic with enclosing surrogate high-level waste glass show that the glass reacts rapidly to alteration products. Glass reaction causes variations in the solution pH in contact with the ceramic materials. We also document variable concentrations of Pu in solution, primarily in colloidal form, which appear to be related to secular variations in solution composition. The apparent dissolution rate of the ceramic waste form, based on Ba concentrations in the effluent, is estimated at {le} 10{sup {minus}5} g/(m{sup 2} {center_dot} d). Pu-bearing colloids were recovered in the size range of 0.2 to 2 {micro}m, but it is not clear that such entities would be transported in a system that is not advective-flow dominated. Results from SPFT experiments give information on the corrosion resistance of two surrogate Pu-ceramics (Ce-pyrochlore and Ce-zirconolite) at 90 C over a pH range of 2 to 12. The two ceramics were doped with minor quantities ({approximately}0.1 mass%) of MoO{sub 3}, so that concentrations of Mo in the effluent solution could be used to monitor the reaction behavior of the materials. The data obtained thus far from experiments with durations up to 150 d do not conclusively prove that the solid-aqueous solution systems have reached steady-state conditions. Therefore, the dissolution mechanism cannot be determined. Apparent dissolution rates of the two ceramic materials based on Ce, Gd, and Mo concentrations in the effluent solutions from the SPFT are nearly identical and vary between 1.1 to 8.5 x 10{sup {minus}4} g/(m{sup 2} {center_dot} d). In addition, the data reveal a slightly amphoteric dissolution behavior, with a minimum apparent rate at pH = 7 to 8, over the pH range examined. Results from two related ceramic samples suggest that radiation damage can have a measurable effect on the dissolution of titanium-based ceramics. The rare earth pyrochlores, Gd{sub 2}Ti{sub 2}O{sub 7} and Lu{sub 2}Ti{sub 2}O{sub 7}, are being studied as part of the DOE Environmental Management Science Program, and the results are germane to this study. The corrosion resistances of both heavy-ion bombarded and pristine (non-bombarded) specimens are being examined with the SPFT test. Initial data indicate that the dissolution rate may increase by a factor of 3 times or more when these materials become amorphous from radiation damage.

  6. A 250 GHz microwave interferometer for divertor experiments on DIII-D

    SciTech Connect

    James, R.A.; Nilson, D.G.; Stever, R.D.; Hill, D.N.; Casper, T.A.

    1994-01-31

    A new 250 GHz, two-frequency microwave interferometer system has been developed to diagnose divertor plasmas on DIII-D. This diagnostic will measure the line-averaged density across both the inner and outer, lower divertor legs. With a cut-off density of over 7 {times} 10{sup 14} cm{sup {minus}3}, temporal measurements of ELMs, MARFs and plasma detachment are expected. The outer leg system will use a double pass method while the inner leg system will be single pass. Two special 3D carbon composite tiles are used, one to protect the microwave antennas mounted directly under the strike point and the other as the outer leg reflecting surface. Performance, design constraints, and the thermalmechanical design of the 3D carbon composite tiles are discussed.

  7. A 250-GHz microwave interferometer for divertor experiments on DIII-D

    SciTech Connect

    James, R.A.; Nilson, D.G.; Stever, R.D.; Hill, D.N.; Casper, T.A. (Lawrence Livermore National Laboratory, University of California, Livermore, California 94551 (United States))

    1995-01-01

    A new 250-GHz, two-frequency microwave interferometer system has been developed to diagnose divertor plasmas on DIII-D. This diagnostic will measure the line-averaged density across both the inner and outer, lower divertor legs. With a cutoff density of over 7[times]10[sup 14] cm[sup [minus]3], temporal measurements of edge localized modes (ELMs) and plasma detachment are expected. The outer-leg system will use a double-pass method while the inner-leg system will be single pass. Two special three-dimensional (3D) carbon composite tiles are used, one to protect the microwave antennas mounted directly under the strike point and the other as the outer-leg reflecting surface. Performance, design constraints, and the thermal-mechanical design of the 3D carbon composite tiles are discussed.

  8. RADAR PRINCIPLES I Introduction

    E-print Network

    Sato, Toru

    ) bands. Antenna size of weather radarsis a few to about ten metersin diameter, but an} atmospheric radar atmospheric radars have antennas witli dialneter of 10- 300 in. Weather radars cover a wide horizontal areaRADAR PRINCIPLES I Introduction Radar is a general technique, willcli has a wide range

  9. Limitations of Radar Coordinates

    E-print Network

    Donato Bini; Luca Lusanna; Bahram Mashhoon

    2004-12-17

    The construction of a radar coordinate system about the world line of an observer is discussed. Radar coordinates for a hyperbolic observer as well as a uniformly rotating observer are described in detail. The utility of the notion of radar distance and the admissibility of radar coordinates are investigated. Our results provide a critical assessment of the physical significance of radar coordinates.

  10. Imaging Electron Interferometer

    NASA Astrophysics Data System (ADS)

    Leroy, B. J.; Bleszynski, A. C.; Aidala, K. E.; Westervelt, R. M.; Kalben, A.; Heller, E. J.; Shaw, S. E.; Maranowski, K. D.; Gossard, A. C.

    2005-04-01

    An imaging interferometer was created in a two-dimensional electron gas by reflecting electron waves emitted from a quantum point contact with a circular mirror. Images of electron flow obtained with a scanning probe microscope at liquid He temperatures show interference fringes when the mirror is energized. A quantum phase shifter was created by moving the mirror via its gate voltage, and an interferometric spectrometer can be formed by sweeping the tip over many wavelengths. Experiments and theory demonstrate that the interference signal is robust against thermal averaging.

  11. Improved Skin Friction Interferometer

    NASA Technical Reports Server (NTRS)

    Westphal, R. V.; Bachalo, W. D.; Houser, M. H.

    1986-01-01

    An improved system for measuring aerodynamic skin friction which uses a dual-laser-beam oil-film interferometer was developed. Improvements in the optical hardware provided equal signal characteristics for each beam and reduced the cost and complexity of the system by replacing polarization rotation by a mirrored prism for separation of the two signals. An automated, objective, data-reduction procedure was implemented to eliminate tedious manual manipulation of the interferometry data records. The present system was intended for use in two-dimensional, incompressible flows over a smooth, level surface without pressure gradient, but the improvements discussed are not limited to this application.

  12. An interferometric radar for non-contact measurement of deflections on civil engineering structures: laboratory and full-scale tests

    Microsoft Academic Search

    Carmelo Gentile; Giulia Bernardini

    2010-01-01

    Recent progress in radar techniques and systems has led to the development of a microwave interferometer, potentially suitable for non-contact vibration monitoring of civil engineering structures. The main characteristic of the new radar system, named IBIS-S, is the possibility of simultaneously measuring the (static or dynamic) displacement at several points of a structure with high sensitivity. The paper first describes

  13. TRMM radar

    NASA Technical Reports Server (NTRS)

    Okamoto, Kenichi

    1993-01-01

    The results of a conceptual design study and the performance of key components of the Bread Board Model (BBM) of the Tropical Rainfall Measuring Mission (TRMM) radar are presented. The radar, which operates at 13.8 GHz and is designed to meet TRMM mission objectives, has a minimum measurable rain rate of 0.5 mm/h with a range resolution of 250 m, a horizontal resolution of about 4 km, and a swath width of 220 km. A 128-element active phased array system is adopted to achieve contiguous scanning within the swath. The basic characteristics of BBM were confirmed by experiments. The development of EM started with the cooperation of NASDA and CRL.

  14. Single-shot interferometer: Development and Testing

    E-print Network

    ;Interferometer Results · HeNe ­ Alignment ­ Visually observed interference pattern · Co2 ­ Golay cell ­ Interferometer ­ Detector Array ­ Reconstruction Algorithm · Hurdles ­ THz Optics ­ Alignment ­ THz transmission

  15. First Results of the TOPSAR C-Band / L-Band Interferometer: Calibration and Differential Penetration

    NASA Technical Reports Server (NTRS)

    Rosen, Paul A.; Hensley, Scott

    1996-01-01

    The NASA/JPL TOPSAR instrument recently was extended from a single wavelength C-band dual aperture synthetic aperture radar (SAR) interferometer to include a second wavelength at the L-band. Adding the second wavelength invites comparison of wavelength-diverse effects in topographic mapping of surfaces, with the principal goal of understanding the penetration of the radar signals in vegetation canopies, and determining the inferred topographic height. A first analysis of these data was conducted at two sites. Elkhorn Slough near Monterey, California presented flat, vegetation free terrain required for calibrating the radar interferometer parameters. A second site stretching from San Jose to Santa Cruz, California, which is heavily vegetated, provided the first test case for wavelength diverse penetration studies. Preliminary results show that: (a) the interferometer calibration determined at Elkhorn Slough is extenable to Laurel Quad and gives confidence in the C- and L-band height measurements; (b) Clear differences were observed between the C- and L-band heights associated with vegetation, with the C-band derived topographic heights generally higher than those from L-band. The noise level in the L-band interferometer is presently the limiting factor in penetration studies.

  16. The single antenna interferometer

    SciTech Connect

    Fitch, J.P.

    1990-01-15

    Air and space borne platforms using synthetic aperture radars (SAR) have made interferometric measurements by using either two physical antennas mounted on one air-frame or two passes of one antenna over a scene. In this paper, a new interferometric technique using one pass of a single-antenna SAR system is proposed and demonstrated on data collected by the NASA-JPL AirSAR. Remotely sensed L-band microwave data are used to show the sensitivity of this technique to ocean surface features as well as a baseline for comparison with work by others using two-antenna systems. 7 refs., 3 figs.

  17. Imaging Electron Interferometer

    NASA Astrophysics Data System (ADS)

    Bleszynski, A. C.; Aidala, K. E.; LeRoy, B. J.; Westervelt, R. M.; Heller, E. J.; Maranowski, K. D.; Gossard, A. C.

    2005-06-01

    An imaging electron interferometer was created in a two-dimensional electron gas (2DEG) using a liquid-He cooled scanning probe microscope (SPM). Electron waves emitted from a quantum point contact (QPC) return to the QPC along two paths: reflection from a concave mirror formed by a gate, and backscattering from the depleted disc underneath the charged SPM tip. Interference of these waves when they return to the QPC produces strong interference fringes in images of electron flow. A quantum phase shifter is formed by moving the mirror via its gate voltage — the fringes move a corresponding amount. The coherent fringes are robust to thermal averaging when the lengths of the two paths are within lT = ?vF/?kBT of each other.

  18. The Fizeau Interferometer Testbed

    NASA Technical Reports Server (NTRS)

    Zhang, Xiaolei; Carpenter, Kenneth G.; Lyon, Richard G,; Huet, Hubert; Marzouk, Joe; Solyar, Gregory

    2003-01-01

    The Fizeau Interferometer Testbed (FIT) is a collaborative effort between NASA's Goddard Space Flight Center, the Naval Research Laboratory, Sigma Space Corporation, and the University of Maryland. The testbed will be used to explore the principles of and the requirements for the full, as well as the pathfinder, Stellar Imager mission concept. It has a long term goal of demonstrating closed-loop control of a sparse array of numerous articulated mirrors to keep optical beams in phase and optimize interferometric synthesis imaging. In this paper we present the optical and data acquisition system design of the testbed, and discuss the wavefront sensing and control algorithms to be used. Currently we have completed the initial design and hardware procurement for the FIT. The assembly and testing of the Testbed will be underway at Goddard's Instrument Development Lab in the coming months.

  19. Single-pass sum-frequency-generation of 589-nm yellow light based on dual-wavelength Nd:YAG laser with periodically-poled LiTaO(3) crystal.

    PubMed

    Zhao, L N; Su, J; Hu, X P; Lv, X J; Xie, Z D; Zhao, G; Xu, P; Zhu, S N

    2010-06-21

    We demonstrate a compact all-solid-state yellow laser source based on Q-switched dual-wavelength Nd:YAG laser and periodically-poled LiTaO(3) crystal. 589-nm yellow light was generated by single-pass sum-frequency generation of the fundamental IR waves at 1064 and 1319 nm. The maximum output power of yellow light was 506 mW and the corresponding conversion efficiency was approximately 5.5% [W(-1)cm(-1)]. PMID:20588462

  20. Radar: The Cassini Titan Radar Mapper

    Microsoft Academic Search

    C. Elachi; M. D. Allison; L. Borgarelli; P. Encrenaz; E. Im; M. A. Janssen; W. T. K. Johnson; R. L. Kirk; R. D. Lorenz; J. I. Lunine; D. O. Muhleman; S. J. Ostro; G. Picardi; F. Posa; C. G. Rapley; L. E. Roth; R. Seu; L. A. Soderblom; S. Vetrella; S. D. Wall; C. A. Wood; H. A. Zebker

    2004-01-01

    The Cassini RADAR instrument is a multimode 13.8 GHz multiple-beam sensor that can operate as a synthetic-aperture radar (SAR) imager, altimeter, scatterometer, and radiometer. The principal objective of the RADAR is to map the surface of Titan. This will be done in the imaging, scatterometer, and radiometer modes. The RADAR altimeter data will provide information on relative elevations in selected

  1. Future Trends in Automotive Radar \\/ Imaging Radar

    Microsoft Academic Search

    J. Wenger

    1998-01-01

    There is a growing interest of car manufacturers in sensors monitoring the car's surrounding area in order to improve safety systems from mere crash survival to crash prediction or prevention by early detection of hazardous situations. Therefore radar sensors have been intensively investigated for many years. A large variety of radar based vehicular sensors have been developed. Narrow-beam radars are

  2. Three-Dimensional Interferometer System

    NASA Astrophysics Data System (ADS)

    Pfeifer, T.; Waltar, Johann

    1990-04-01

    A new arrangement of interferometers allows to measure the movement of a retroreflector in space with high precision. Applications are the testing of the position accuracy of three dimensional coordinate machines, industrial mbots, tooling machines etc. This system uses four Michelson interferometers with deflector units, controlled by a servo system. For the position of the retro-reflector and the position of the deflector units are unknown at start-up, a at least ten point calibration cycle is necessary. A mathematical algorithm, using the signals of the four Michelson interferometers, allows to determine the position of the retroreflector and the deflector units in a given coordinate system.

  3. Observation and theory of the radar aurora

    SciTech Connect

    Sahr, J.D.

    1990-01-01

    Plasma density irregularities occurring near the Aurora Borealis cause scattering of HF, VHF, and UHF radio waves. Analysis of the resulting radar signal provides great detail about the spatial and temporal characteristics of these auroral E region irregularities. Observations are presented of the radar aurora from recent campaigns in northern Sweden. After reviewing the basic theory and observations of auroral electrojet irregularities, a simple nonlinear fluid theory of electrojet ion-acoustic waves is introduced, and reduced to a form of the three-wave interaction equations. This theory provides a simple mechanism for excitation of linearly stable waves at large aspect and flow angles, as well as a prediction of the power spectra that a coherent scatter radar should observe. In addition, this theory may be able to account for type 3 waves without resorting to ion gyro modes, such as the electrostatic ion-cyclotron wave. During the course of the research a simple new radar transmitting mode and signal processing algorithm was generated which very simply solves a frequency aliasing problem that often occurs in CUPRI auroral radar studies. Several new radar data analysis routines were developed, including the principally cross-beam image and scatter plots of the second versus first moments of the power spectrum of the irregularities. Analysis of vertical interferometer data shows that type 3 waves originate at ordinary electrojet altitudes, not in the upper E region, from which it is concluded that the electrostatic ion-cyclotron mode does not generate type 3 waves. The measured height of type 3 waves and other spectral analyses provide support for the pure ion-acoustic theory of type 3 waves. Suggestions are offered for hardware improvements to the CUPRI radar, new experiments to test new and existing theories.

  4. Radar frequency radiation

    Microsoft Academic Search

    E. Malowicki

    1981-01-01

    A method is presented for the determination of radar frequency radiation power densities that the PAVE PAWS radar system could produce in its air and ground environment. The effort was prompted by the concern of the people in the vicinity of OTIS AFB MA and BEALE AFB CA about the possible radar frequency radiation hazard of the PAVE PAWS radar.

  5. GMTI MIMO radar

    Microsoft Academic Search

    D. W. Bliss; K. W. Forsythe; S. K. Davis; G. S. Fawcett; D. J. Rabideau; L. L. Horowitz; S. Kraut

    2009-01-01

    Multiple-input multiple-output (MIMO) extensions to radar systems enable a number of advantages compared to traditional approaches. These advantages include improved angle estimation and target detection. In this paper, MIMO ground moving target indication (GMTI) radar is addressed. The concept of coherent MIMO radar is introduced. Comparisons are presented comparing MIMO GMTI and traditional radar performance. Simulations and theoretical bounds for

  6. Spaceborne weather radar

    Microsoft Academic Search

    Robert Meneghini; Toshiaki Kozu

    1990-01-01

    The present work on the development status of spaceborne weather radar systems and services discusses radar instrument complementarities, the current forms of equations for the characterization of such aspects of weather radar performance as surface and mirror-image returns, polarimetry, and Doppler considerations, and such essential factors in spaceborne weather radar design as frequency selection, scanning modes, and the application of

  7. Wind shear radar simulation

    NASA Technical Reports Server (NTRS)

    Britt, Charles L.

    1988-01-01

    Viewgraphs used in a presentation on wind shear radar simulation are given. Information on a microburst model of radar reflectivity and wind velocity, radar pulse output, the calculation of radar return, microburst power spectrum, and simulation plans are given. A question and answer session is transcribed.

  8. A general statistical instrument theory of atmospheric and ionospheric radars

    SciTech Connect

    Woodman, R.F. (Instituto Geofisico del Peru, Lima (Peru))

    1991-05-01

    Some basic functional relationships between the statistics of the signals received in a radar and the statistics of the density fluctuations of a scattering medium are derived. They vary in their degree of generality, but they are all very general in scope. They include monostatic and bistatic radars scattering from either atmospheric, ionospheric, or meteorological media. They are valid for refractive and slightly dispersive media, so they can also be used for HF ionospheric radars. They include the effects of filtering, including receiver filtering, pulse compression coding and decoding schemes, and coherent integration, or any alternative linear digital filtering scheme. Functional relationships to include cross-correlation schemes, such as Faraday rotation experiments and interferometers, are included. Some simplified expressions are derived for frequently encountered situations, where different approximations can be made. These simplified expressions cover a large number of radar techniques currently in use for atmospheric and ionospheric applications.

  9. The Einstein polarization interferometer for cosmology (EPIC) and the millimeter-wave bolometric interferometer (MBI)

    E-print Network

    Timbie, Peter

    The Einstein polarization interferometer for cosmology (EPIC) and the millimeter-wave bolometric). Our study investigates the advantages and tradeoffs of using an interferometer (EPIC) for the mission

  10. Two-Frequency Paired Polarization Interferometer for Faraday Rotation Angle Detection

    NASA Astrophysics Data System (ADS)

    Lin, Chu-En; Chang, Jin-Gor; Chou, Li-Dek; Yu, Chih-Jen; Lee, Cheng-Chung; Chou, Chien

    2009-08-01

    A highly sensitive two-frequency paired linear polarized interferometer (TPPI) for measuring the Faraday rotation angle and Verdet constant of the Bi12SiO20 (BSO) crystal in real time was set up by an amplitude-sensitive detection method. TPPI features a common-path heterodyne interferometer in conjunction with a highly correlated paired linear polarized laser beam. Then, the antisymmetry of polarized heterodyne signals is produced and Faraday rotation angle detection by a balanced detector scheme is satisfied automatically. As a result, shot-noise-limited detection of Faraday rotation angle is possible. In addition, the Faraday rotation angle detection is also insensitive to the scattering and absorption caused by the specimen because of the common-path propagation of the paired linear polarized laser beam. Experimentally, the sensitivities of Faraday rotation angle and Verdet constant measurements of the BSO crystal under the arrangement with a single pass of the laser beam in TPPI are 4.93×10-5 rad/mm and 2.6×10-7 rad/(mT·mm), respectively. This suggests that the Faraday rotation angle detection sensitivity has the potential to be on the order of 10-8 rad/mm if a Fabry-Perot cavity with a finesse of F=120 is used in TPPI.

  11. The Analysis of Moonborne Cross Track Synthetic Aperture Radar Interferometry for Global Environment Change Monitoring

    NASA Astrophysics Data System (ADS)

    Yixing, Ding; Huadong, Guo; Guang, Liu; Daowei, Zhang

    2014-03-01

    Faced to the earth observation requirement of large scale global environment change, a SAR (Synthetic Aperture Radar) antenna system is proposed to set on Moon's surface for interferometry in this paper. With several advantages superior to low earth obit SAR, such as high space resolution, large range swath and short revisit interval, the moonborne SAR could be a potential data resource of global changes monitoring and environment change research. Due to the high stability and ease of maintenance, the novel system is competent for offering a long and continuous time series of remote sensing imagery. The Moonborne SAR system performance is discussed at the beginning. Then, the peculiarity of interferometry is analyzed in both repeat pass and single pass cases. The chief distinguishing feature which is worth to research the potentiality of repeat pass interferometry is that the revisit interval is reduced to one day in most cases, and in worst case one month. Decorrelation deriving from geometry variety is discussed in detail. It turns out that the feasibility of moonborne SAR repeat pass interferometry depends on the declination of Moon. The severity of shift effects in radar echoes increased as Moon approaches to the equatorial plane. Moreover, referring to the single pass interferometry, two antennas are assumed to set on different latitude of Moon. There is enough space on Moon to form a long baseline, which is highly related to the interferogram precision.

  12. A microwave interferometer as a non-contacting cardio-pulmonary monitor

    Microsoft Academic Search

    P. E. Engler; S. S. Reisman; C. Y. Ho

    1988-01-01

    A coherent, phase-locked microwave interferometer radar system that records the mechanical vibrations of the surface of the chest cavity resulting from the cardiac activity within the chest is described. The instrument operates at 9.3 GHz, which corresponds to a free-space wavelength of 3.1 cm. With a phase resolution of about 0.01° of carrier phase shift, the system has the capability

  13. IR interferometers using modern cameras

    NASA Astrophysics Data System (ADS)

    Ai, Chiayu

    1997-11-01

    Laser interferometers have been used widely in the optics and disk drive industries. Often the surface of the sample is either too curved to resolve the fringes or too rough to reflect the incident beam back into the interferometer. Illuminating at a graze incident angle effectively increases the equivalent wavelength, and hence the reflectivity, but the image of a circular aperture becomes elliptical. Lasers with a long IR wavelength seem to be the solution. However,the spatial resolution of the vidicon cameras is usually poor, and the image lag is often too long. These limit the accuracy of an IR phase-shifting interferometer. Recently, we have designed tow types of interferometers for 3.39 micrometers and 10.6 micrometers using an InSb array and a micro- bolometer array, respectively. These modern cameras have a high resolution and hence greatly extend the range of measurable material from a blank to a finished optics. Because the refractive index of the optical material at the IR wavelength is usually very high, the anti-reflection coating of the optics at IR is more critical than that at a visible wavelength. The interferometer's design, the resolution, the dependence of the fringe contrast on the sample roughness, and the measurement results of various samples are presented.

  14. First Results of the TOPSAR C-Band/L-Band Interferometer: Calibration and Differential Penetration

    NASA Technical Reports Server (NTRS)

    Rosen, Paul A.; Hensley, Scott

    1996-01-01

    The NASA/JPL TOPSAR instrument recently was extended from a single- wavelength C-band (5.6 cm-lambda) dual aperture synthetic aperture radar interferometer to include a second wavelength at L-band (24 cm). Adding the second wavelength invites comparison of wavelength-diverse effects in topographic mapping of surfaces, with the principal goal of understanding the penetration of the radar signals in vegetation canopies, and determining the inferred topographic height. A first analysis of these data was conducted at two sites. Elkhorn Slough near Monterey, California presented flat, vegetation free terrain required for calibrating the radar interferometric parameters. A second site stretching from San Jose to Santa Cruz, CA, which is heavily vegetated, provided the first test case for wavelength diverse penetration studies. Preliminary results show that: (a) the interferometer calibration determined at Elkhorn Slough is extendable to Laurel Quad and gives confidence in the C- and L-band height measurements; and (b) Clear differences are observed between the C- and L-band heights associated with vegetation, with C-band-derived topographic heights generally higher than those from L-band. The noise level in the L-band interferometer is presently the limiting factor in penetration studies.

  15. Laser Altimeter Evaluation of an SRTM DEM for Western Washington State

    Microsoft Academic Search

    C. C. Carabajal; D. J. Harding

    2002-01-01

    Interferometric Synthetic Aperture Radar (InSAR) and laser altimeter measurements of topography provide complimentary approaches to characterize landforms. Results from the Shuttle Radar Topography Mission (SRTM) will provide an unprecedented, near-global, Digital Elevation Model (DEM) at 30 m resolution using a single pass C-band (5.6 cm wavelength) radar interferometer. In vegetated terrains, the C-band radar energy penetrates part way into vegetation

  16. Remorque RADAR Description technique

    E-print Network

    Heurteaux, Yanick

    ANNEXE: Remorque RADAR Description technique Le but de la remorque est de transporter un RADAR et pour héberger l'électronique radar et son opérateur. Caractéristiques générales de la remorque : · PTC'un côté, une baie de l'autre. Un hublot sur le toit et une baie donnant sur la partie RADAR. Un plafonnier

  17. UWB RADAR Receiver Architecture

    Microsoft Academic Search

    Nuno Paulino; Adolfo Steiger Garção; João Goes

    this chapter describes the operation of a radar system. The differences and advantages of using UWB signals in the radar system,\\u000a over traditional narrow band signals, are discussed. The radar equation, usually defined for narrow band signals, is redefined\\u000a for UWB signals. This new radar equation is used to analyze the echo signals from targets with basic shapes, resulting in

  18. Fiber-optic coupled heterodyne interferometer

    Microsoft Academic Search

    Liang Zhang

    2003-01-01

    A lightweight and electrically passive interferometer is demanded by a number of applications for precision metrology such as machine tool metrology and on-machine feedback. To satisfy these requirements, a fiber-optic coupled heterodyne displacement measuring Michelson interferometer is developed. In this interferometer, the laser light is coupled into the interferometer with a polarization-maintaining (PM) fiber to separate the application environment of

  19. Cassini Titan Radar Mapper

    Microsoft Academic Search

    CHARLES ELACHI; E. Im; L. E. Roth; C. L. Werner

    1991-01-01

    The Cassini Titan Radar Mapper is a multimode radar instrument designed to probe the optically inaccessible surface of Titan, Saturn's largest moon. The instrument is to be included in the payload of the Cassini Saturn Mission, scheduled for launch in 1995. The individual modes of Cassini Radar Mapper will allow topographic mapping and surface imaging at few hundred meters resolution.

  20. Lunar radar backscatter studies

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.

    1979-01-01

    The lunar surface material in the Plato area is characterized using Earth based visual, infrared, and radar signatures. Radar scattering in the lunar regolith with an existing optical scattering computer program is modeled. Mapping with 1 to 2 km resolution of the Moon using a 70 cm Arecibo radar is presented.

  1. Microwave interferometer controls cutting depth of plastics

    NASA Technical Reports Server (NTRS)

    Heisman, R. M.; Iceland, W. F.

    1969-01-01

    Microwave interferometer system controls the cutting of plastic materials to a prescribed depth. The interferometer is mounted on a carriage with a spindle and cutting tool. A cross slide, mounted on the carriage, allows the interferometer and cutter to move toward or away from the plastic workpiece.

  2. Interferometer for the measurement of plasma density

    DOEpatents

    Jacobson, Abram R. (Los Alamos, NM)

    1980-01-01

    An interferometer which combines the advantages of a coupled cavity interferometer requiring alignment of only one light beam, and a quadrature interferometer which has the ability to track multi-fringe phase excursions unambiguously. The device utilizes a Bragg cell for generating a signal which is electronically analyzed to unambiguously determine phase modulation which is proportional to the path integral of the plasma density.

  3. Slow wave atom interferometers for rotation sensing

    Microsoft Academic Search

    Meriç Özcan

    2007-01-01

    A gyroscope based on Sagnac interferometer measures the rotation rate relative to an inertial frame of reference. Sagnac effect originally has been derived and experimentally demonstrated with optical waves. Later, matter wave based Sagnac interferometers were developed due to inherent sensitivity over a photon based system. However in any interferometer whether it is photon or matter wave based the resultant

  4. The laser interferometer: Application to plasma diagnostics

    Microsoft Academic Search

    J. B. Gerardo; J. T. Verdeyen

    1964-01-01

    A laser interferometer employing a reference arm with a spherical mirror is discussed. This interferometer is extremely promising in many fields of scientific endeavor, for instance, in plasma physics, due to its simplicity and high sensitivity. Its sensitivity is greater than that of a similar interferometer with planar mirrors because the closely spaced normal modes with nonzero transverse indexes can

  5. Holographic Twyman-Green interferometer

    NASA Technical Reports Server (NTRS)

    Chen, C. W.; Breckinridge, J. B.

    1982-01-01

    A dichromated gelatin off-axis Fresnel zone plate was designed, fabricated, and used in a new type of interferometer for optical metrology. This single hologram optical element combines the functions of a beam splitter, beam diverger, and aberrated null lens. Data presented show the successful application for an interferometric test of an f/6, 200-mm diam parabolic mirror.

  6. Radar Meteorology Tutorial

    NSDL National Science Digital Library

    McNoldy, Brian

    Brian McNoldy at Multi-community Environmental Storm Observatory (MESO) educates the public about the use of radar in meteorology in this pdf document. After reading about the history of radar, visitors can find out how radar can detect storms by transmitting a high-power beam of radiation. Students can learn how scatter, absorption, frequencies, scan angles, and moments impact the radar display. With the help of many example images, the author also discusses how to interpret the images collected. At the end of the online document, visitors can learn about the characteristics and capabilities of NEXRAD WSR-88D, the radar used throughout the United States.

  7. Multidimensional radar picture

    NASA Astrophysics Data System (ADS)

    Waz, Mariusz

    2010-05-01

    In marine navigation systems, the three-dimensional (3D) visualization is often and often used. Echosonders and sonars working in hydroacustic systems can present pictures in three dimensions. Currently, vector maps also offer 3D presentation. This presentation is used in aviation and underwater navigation. In the nearest future three-dimensional presentation may be obligatory presentation in displays of navigation systems. A part of these systems work with radar and communicates with it transmitting data in a digital form. 3D presentation of radar picture require a new technology to develop. In the first step it is necessary to compile digital form of radar signal. The modern navigation radar do not present data in three-dimensional form. Progress in technology of digital signal processing make it possible to create multidimensional radar pictures. For instance, the RSC (Radar Scan Converter) - digital radar picture recording and transforming tool can be used to create new picture online. Using RSC and techniques of modern computer graphics multidimensional radar pictures can be generated. The radar pictures mentioned should be readable for ECDIS. The paper presents a method for generating multidimensional radar picture from original signal coming from radar receiver.

  8. Standing waves in fiber-optic interferometers.

    PubMed

    de Haan, V; Santbergen, R; Tijssen, M; Zeman, M

    2011-10-10

    A study is presented giving the response of three types of fiber-optic interferometers by which a standing wave through an object is investigated. The three types are a Sagnac, Mach-Zehnder and Michelson-Morley interferometer. The response of the Mach-Zehnder interferometer is similar to the Sagnac interferometer. However, the Sagnac interferometer is much harder to study because of the fact that one input port and output port coincide. Further, the Mach-Zehnder interferometer has the advantage that the output ports are symmetric, reducing the systematic effects. Examples of standing wave light absorption in several simple objects are given. Attention is drawn to the influence of standing waves in fiber-optic interferometers with weak-absorbing layers incorporated. A method is described for how these can be theoretically analyzed and experimentally measured. Further experiments are needed for a thorough comparison between theory and experiment. PMID:22015361

  9. The wide swath ocean altimeter: radar interferometry for global ocean mapping with centimetric accuracy

    NASA Technical Reports Server (NTRS)

    Pollard, Brian D.; Rodriguez, Ernesto; Veilleux, Louise; Akins, Torry; Brown, Paula; Kitiyakara, Amirit; Zawadski, Mark

    2002-01-01

    We have developed an instrument concept that combines a conventional nadir altimeter with a radar interferometer to meet the above requirements. In this paper, we describe the overall mission concept and the interferometric radar design. We also describe several new technology developments that facilitate the inclusion of this instrument on a small, inexpensive spacecraft bus. Those include ultra-light, deployable reflectarray antennas for the radar interferometer; a novel five frequency feed horn for the radiometer and altimeter; a lightweight, low power integrated three frequency radiometer; and a field programmable gate array-based onboard data processor. Finally, we discuss recent algorithm developments for the onboard date processing, and present the expected instatements performance improvements over previously reported results.

  10. Multistatic radar systems signal processing

    Microsoft Academic Search

    I. Bradaric; G. T. Capraro; D. D. Weiner; M. C. Wicks

    2006-01-01

    In this paper, a multistatic radar system with multiple receivers and one transmitter is analyzed. We address the rules for selecting the weights for fusing multiple receivers in order to meet pre-specified performance goals. A multistatic radar ambiguity function is used to relate different radar performance measures to system parameters such as radar geometry and radar waveforms. Simulations are used

  11. Apollo experience report: Lunar module landing radar and rendezvous radar

    NASA Technical Reports Server (NTRS)

    Rozas, P.; Cunningham, A. R.

    1972-01-01

    A developmental history of the Apollo lunar module landing and rendezvous radar subsystems is presented. The Apollo radar subsystems are discussed from initial concept planning to flight configuration testing. The major radar subsystem accomplishments and problems are discussed.

  12. The TEXT upgrade vertical interferometer

    SciTech Connect

    Hallock, G.A.; Gartman, M.L.; Li, W.; Chiang, K.; Shin, S.; Castles, R.L.; Chatterjee, R.; Rahman, A.S. (The University of Texas at Austin, Austin, Texas 78712 (United States))

    1992-10-01

    A far-infrared interferometer has been installed on TEXT upgrade to obtain electron density profiles. The primary system views the plasma vertically through a set of large (60-cm radial{times}7.62-cm toroidal) diagnostic ports. A 1-cm channel spacing (59 channels total) and fast electronic time response is used, to provide high resolution for radial profiles and perturbation experiments. Initial operation of the vertical system was obtained late in 1991, with six operating channels.

  13. MIMO radar, SIMO radar, and IFIR radar: a P. P. Vaidyanathan and Piya Pal

    E-print Network

    Vaidyanathan, P. P.

    MIMO radar, SIMO radar, and IFIR radar: a comparison P. P. Vaidyanathan and Piya Pal Dept and SIMO radar systems for the case where the transmitter and receiver are collocated. The simplicity of the application allows one to see clearly where the advantages of MIMO radar come from, and what the tradeoffs are

  14. Radar in transition

    NASA Astrophysics Data System (ADS)

    Barton, D. K.

    1984-12-01

    It is pointed out that radar engineers, at the end of 1984, find their field in transition between the conventional designs of the post War II era and the digitally controlled, solid-state systems which will be in place for the year 2000. The U.S. Navy has two major phased array radar systems in operation, including the rotating three-dimensional (3D) AN/SPS-48, and the phased-scanned AN/SPY-1 (Aegis) radars. The Aegis represents a major step beyond the conventional 3D and mechanical fire-control radars. However, it requires a special ship, dedicated to its use. Attention is given to questions regarding an extension of the application of Aegis technology to other U.S. Navy applications and to other navies, an ambitious solid-state radar program in the UK, and Army radars.

  15. Radar performance improvement

    Microsoft Academic Search

    G. R. Little

    1976-01-01

    The AN\\/APQ-153 fire control radar modified to provide angle tracking was evaluated for improved performance. The frequency agile modifications are discussed along with the range-rate improvement modifications, and the radar to computer interface. A parametric design and comparison of noncoherent and coherent radar systems are presented. It is shown that the shuttle rendezvous range and range-rate requirements can be made

  16. Caribbean Radar Cases

    NSDL National Science Digital Library

    2014-09-14

    This module presents radar case studies taken from events in the Caribbean that highlight radar signatures of severe weather. These cases include examples of deep convection, squall lines, bow echoes, tornadoes, and heavy rain resulting in flooding. Each case study includes a discussion of the conceptual models of each type of event as a review before showing the radar signatures and allowing the learner to analyze each one.

  17. Equatorial radar system

    NASA Technical Reports Server (NTRS)

    Rukao, S.; Tsuda, T.; Sato, T.; Kato, S.

    1989-01-01

    A large clear air radar with the sensitivity of an incoherent scatter radar for observing the whole equatorial atmosphere up to 1000 km altitude is now being designed in Japan. The radar, called the Equatorial Radar, will be built in Pontianak, Kalimantan Island, Indonesia (0.03 N, 109.3 E). The system is a 47 MHz monostatic Doppler radar with an active phased array configuration similar to that of the MU radar in Japan, which has been in successful operation since 1983. It will have a PA product of more than 5 x 10(9) sq. Wm (P = average transmitter power, A = effective antenna aperture) with sensitivity more than 10 times that of the MU radar. This system configuration enables pulse-to-pulse beam steering within 25 deg from the zenith. As is the case of the MU radar, a variety of sophisticated operations will be made feasible under the supervision of the radar controller. A brief description of the system configuration is presented.

  18. The Invisible Radar Triangle

    NSDL National Science Digital Library

    2014-09-18

    Students learn about radar imaging and its various military and civilian applications that include recognition and detection of human-made targets, and the monitoring of space, deforestation and oil spills. They learn how the concepts of similarity and scaling are used in radar imaging to create three-dimensional models of various targets. Students apply the critical attributes of similar figures to create scale models of a radar imaging scenario using infrared range sensors (to emulate radar functions) and toy airplanes (to emulate targets). They use technology tools to measure angles and distances, and relate the concept of similar figures to real-world applications.

  19. Nonlocal polarization interferometer for entanglement detection

    SciTech Connect

    Williams, Brian P [ORNL; Humble, Travis S [ORNL; Grice, Warren P [ORNL

    2014-01-01

    We report a nonlocal interferometer capable of detecting entanglement and identifying Bell states statistically. This is possible due to the interferometer's unique correlation dependence on the antidiagonal elements of the density matrix, which have distinct bounds for separable states and unique values for the four Bell states. The interferometer consists of two spatially separated balanced Mach-Zehnder or Sagnac interferometers that share a polarization-entangled source. Correlations between these interferometers exhibit nonlocal interference, while single-photon interference is suppressed. This interferometer also allows for a unique version of the Clauser-Horne-Shimony-Holt Bell test where the local reality is the photon polarization. We present the relevant theory and experimental results.

  20. Generalized radar/radiometry imaging problems

    E-print Network

    Genève, Université de

    Paper Generalized radar/radiometry imaging problems Ivan Prudyus, Sviatoslav Voloshynovskiy, Andriy- ing simulation based on radar, synthetic aperture radar (SAR) and radiometry systems are presented systems, synthetic aperture radar, spatio-temporal imaging. 1. Introduction Resolution of radar

  1. Cryogenic Michelson interferometer on the space shuttle

    Microsoft Academic Search

    Stan Wellard; Jeff Blakeley; Steven Brown; Brent Bartschi; E. R. Huppi

    1993-01-01

    A helium-cooled interferometer was flown aboard shuttle flight STS-39. This interferometer, along with its sister radiometer, set new benchmarks for the quantity and quality of data collected. The interferometer generated approximately 150,000 interferograms during the course of the flight. Data was collected at tangent heights from the earth's surface to celestial targets. The interferograms encoded spectral data from aurora, earth

  2. Decoherence measure by gravitational wave interferometers

    E-print Network

    Yasushi Mino

    2008-08-14

    We consider the possibility to measure the quantum decoherence using gravitational wave interferometers. Gravitational wave interferometers create the superposition state of photons and measure the interference of the photon state. If the decoherence occurs, the interference of the photon state vanishes and it can be measured by the interferometers. As examples of decoherence mechanisms, we consider 1) decoherence by spontaneous localization, 2) gravitational decoherence and 3) decoherence by extra-dimensional gravity.

  3. A three-grating electron interferometer

    NASA Astrophysics Data System (ADS)

    Gronniger, G.; Barwick, B.; Batelaan, H.

    2006-10-01

    We report the observation of fringes from a three-grating electron interferometer. Interference fringes have been observed at low energies ranging from 6 to 10 keV. Contrasts of up to 25% are recorded and exceed the maximal contrast of the classical equivalent Moiré deflectometer. This type of interferometer could serve as a separate beam Mach Zehnder interferometer for low-energy electron interferometry experiments.

  4. High sensitivity two-frequency paired polarized interferometer in Faraday rotation angle measurement of ambient air with single-traveling configuration

    NASA Astrophysics Data System (ADS)

    Lin, Chu-En; Yu, Chih-Jen; Li, Ying-Chang; Tsai, Chien-Chung; Chou, Chien

    2008-08-01

    High sensitivity detection on Faraday rotation and Verdet constant of ambient air under weak applied magnet field and single-pass configuration specimen is setup in which a two-frequency paired linear polarized interferometer (TPPI) coupled with balanced detector shown at shot-noise-limited detection is demonstrated. The Verdet constant of ambient air at 1.3×10-6 rad/mT m and its sensitivity at 4.3×10-8 rad/mT m were measured. Additionally, this method also is able to extend into a broad spectral range on Faraday rotation angle or Verdet constant measurement. Finally, the enhancement on detection sensitivity by integrating a Fabry-Pérot cavity into TPPI is discussed.

  5. Java Radar Analysis Tool

    NASA Technical Reports Server (NTRS)

    Zaczek, Mariusz P.

    2005-01-01

    Java Radar Analysis Tool (JRAT) is a computer program for analyzing two-dimensional (2D) scatter plots derived from radar returns showing pieces of the disintegrating Space Shuttle Columbia. JRAT can also be applied to similar plots representing radar returns showing aviation accidents, and to scatter plots in general. The 2D scatter plots include overhead map views and side altitude views. The superposition of points in these views makes searching difficult. JRAT enables three-dimensional (3D) viewing: by use of a mouse and keyboard, the user can rotate to any desired viewing angle. The 3D view can include overlaid trajectories and search footprints to enhance situational awareness in searching for pieces. JRAT also enables playback: time-tagged radar-return data can be displayed in time order and an animated 3D model can be moved through the scene to show the locations of the Columbia (or other vehicle) at the times of the corresponding radar events. The combination of overlays and playback enables the user to correlate a radar return with a position of the vehicle to determine whether the return is valid. JRAT can optionally filter single radar returns, enabling the user to selectively hide or highlight a desired radar return.

  6. Noncooperative rendezvous radar system

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A fire control radar system was developed, assembled, and modified. The baseline system and modified angle tracking system are described along with the performance characteristics of the baseline and modified systems. Proposed changes to provide additional techniques for radar evaluation are presented along with flight test data.

  7. Decoders for MST radars

    NASA Technical Reports Server (NTRS)

    Woodman, R. F.

    1983-01-01

    Decoding techniques and equipment used by MST radars are described and some recommendations for new systems are presented. Decoding can be done either by software in special-purpose (array processors, etc.) or general-purpose computers or in specially designed digital decoders. Both software and hardware decoders are discussed and the special case of decoding for bistatic radars is examined.

  8. Phased-array radars

    Microsoft Academic Search

    Eli Brookner

    1985-01-01

    The operating principles, technology, and applications of phased-array radars are reviewed and illustrated with diagrams and photographs. Consideration is given to the antenna elements, circuitry for time delays, phase shifters, pulse coding and compression, and hybrid radars combining phased arrays with lenses to alter the beam characteristics. The capabilities and typical hardware of phased arrays are shown using the US

  9. Determination of radar MTF

    SciTech Connect

    Chambers, D. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    The ultimate goal of the Current Meter Array (CMA) is to be able to compare the current patterns detected with the array with radar images of the water surface. The internal wave current patterns modulate the waves on the water surface giving a detectable modulation of the radar cross-section (RCS). The function relating the RCS modulations to the current patterns is the Modulation Transfer Function (MTF). By comparing radar images directly with co-located CMA measurements the MTF can be determined. In this talk radar images and CMA measurements from a recent experiment at Loch Linnhe, Scotland, will be used to make the first direct determination of MTF for an X and S band radar at low grazing angles. The technical problems associated with comparing radar images to CMA data will be explained and the solution method discussed. The results suggest the both current and strain rate contribute equally to the radar modulation for X band. For S band, the strain rate contributes more than the current. The magnitude of the MTF and the RCS modulations are consistent with previous estimates when the wind is blowing perpendicular to the radar look direction.

  10. Active radar stealth device

    Microsoft Academic Search

    R. N. Cain; Albert J. Corda

    1991-01-01

    This patent discloses an active radar stealth device mounted on a host platform for minimizing the radar cross-section of the host platform. A coating which is essentially microwave transparent is attached to the surface of a host platform and is exposed to an incident microwave field. A plurality of detector\\/emitter pairs contained within the coating detect and actively cancel, respectively,

  11. Diffraction phases in atom interferometers

    E-print Network

    Caroline Champenois; Matthias Buchner; Remi Delhuille; Cecile Robilliard; Jacques Vigue; Alain Miffre

    2003-03-12

    Diffraction of atoms by laser is a very important tool for matter wave optics. Although this process is well understood, the phase shifts induced by this diffraction process are not well known. In this paper, we make analytic calculations of these phase shifts in some simple cases and we use these results to model the contrast interferometer recently built by the group of D. Pritchard at MIT. We thus show that the values of the diffraction phases are large and that they probably contribute to the phase noise observed in this experiment.

  12. Looking at Radar Images

    NSDL National Science Digital Library

    These activities pertain to the value of the different types of images, including a false color mosaic, a Compressed Stokes image, a vegetation map and key, and various ground photographs. Students are given specific directions on how to decide what features of a radar image indicate such structures as upland forest, clear-cut areas, and roads. In a second activity, students look at the radar images to see if they can produce a vegetation map similar to the one they have been given. The third activity introduces 15 Decade Volcanoes that pose a particular threat to humans. Using the Decade Volcanoes as examples, students view radar images of volcanoes that occur around the world. The final exercise is aimed at helping students distinguish the differences between radar image data and visible photographs. Students will look at radar data and photographs of three sites taken by the astronauts.

  13. Spaceborne weather radar

    NASA Technical Reports Server (NTRS)

    Meneghini, Robert; Kozu, Toshiaki

    1990-01-01

    The present work on the development status of spaceborne weather radar systems and services discusses radar instrument complementarities, the current forms of equations for the characterization of such aspects of weather radar performance as surface and mirror-image returns, polarimetry, and Doppler considerations, and such essential factors in spaceborne weather radar design as frequency selection, scanning modes, and the application of SAR to rain detection. Attention is then given to radar signal absorption by the various atmospheric gases, rain drop size distribution and wind velocity determinations, and the characteristics of clouds, as well as the range of available estimation methods for backscattering, single- and dual-wavelength attenuation, and polarimetric and climatological characteristics.

  14. Micropower impulse radar imaging

    SciTech Connect

    Hall, M.S.

    1995-11-01

    From designs developed at the Lawrence Livermore National Laboratory (LLNL) in radar and imaging technologies, there exists the potential for a variety of applications in both public and private sectors. Presently tests are being conducted for the detection of buried mines and the analysis of civil structures. These new systems use a patented ultra-wide band (impulse) radar technology known as Micropower Impulse Radar (GPR) imaging systems. LLNL has also developed signal processing software capable of producing 2-D and 3-D images of objects embedded in materials such as soil, wood and concrete. My assignment while at LLNL has focused on the testing of different radar configurations and applications, as well as assisting in the creation of computer algorithms which enable the radar to scan target areas of different geometeries.

  15. Browse > Conferences> Radar Conference, 2008. RADAR ... INDEX TERMS

    E-print Network

    Préaux, Jean-Philippe

    Browse > Conferences> Radar Conference, 2008. RADAR ... INDEX TERMS REFERENCES CITING DOCUMENTS Force, MorphoAnalysis in Signal Process. Lab., Salon-de-Provence This paper appears in: Radar Conference, 2008. RADAR '08. IEEE Issue Date: 26-30 May 2008 On page(s): 1 - 5 Location: Rome ISSN: 1097-5659 Print

  16. GEOS-3 ocean current investigation using radar altimeter profiling. [Gulf Stream surface topography

    NASA Technical Reports Server (NTRS)

    Leitao, C. D.; Huang, N. E.; Parra, C. G.

    1978-01-01

    Both quasi-stationary and dynamic departures from the marine geoid were successfully detected using altitude measurements from the GEOS-3 radar altimeter. The quasi-stationary departures are observed either as elevation changes in single pass profiles across the Gulf Stream or at the crowding of contour lines at the western and northern areas of topographic maps generated using altimeter data spanning one month or longer. Dynamic features such as current meandering and spawned eddies can be monitored by comparing monthly mean maps. Comparison of altimeter inferred eddies with IR detected thermal rings indicates agreement of the two techniques. Estimates of current velocity are made using derived slope estimates in conjunction with the geostrophic equation.

  17. The DELTA Synchrotron Light Interferometer

    SciTech Connect

    Berges, U. [DELTA, University of Dortmund, Maria-Goeppert-Mayer Str. 2, 4421 Dortmund (Germany); Fachbereich Physik, University of Dortmund, Otto-Hahn-Str. 4, 44221 Dortmund (Germany)

    2004-05-12

    Synchrotron radiation sources like DELTA, the Dortmund Electron Accelerator, a third generation synchrotron light source, need an optical monitoring system to measure the beam size at different points of the ring with high resolution and accuracy. These measurements also allow an investigation of the emittance of the storage ring, an important working parameter for the efficiency of working beamlines with experiments using the synchrotron radiation. The resolution limits of the different types of optical synchrotron light monitors at DELTA are investigated. The minimum measurable beamsize with the normal synchrotron light monitor using visible light at DELTA is about 80 {mu}m. Due to this a synchrotron light interferometer was built up and tested at DELTA. The interferometer uses the same beamline in the visible range. The minimum measurable beamsize is with about 8 {mu}m one order of magnitude smaller. This resolution is sufficient for the expected small vertical beamsizes at DELTA. The electron beamsize and emittance were measured with both systems at different electron beam energies of the storage ring. The theoretical values of the present optics are smaller than the measured emittance. So possible reasons for beam movements are investigated.

  18. In-line Sagnac interferometer current sensor

    Microsoft Academic Search

    J. Blake; P. Tantaswadi; R. T. de Carvalho

    1996-01-01

    The authors demonstrate for the first time a near shot noise limited in-line Sagnac interferometer current sensor. It is shown to have a number of advantages over the optical current sensors based on polarimetric Faraday and Faraday\\/Sagnac loop interferometer topologies, including lower sensitivity to environmental disturbances, less demanding optical components, and easy installation.

  19. Mosaicking with Cosmic Microwave Background Interferometers

    Microsoft Academic Search

    Emory F. Bunn; Martin White

    2007-01-01

    Measurements of cosmic microwave background (CMB) anisotropies by interferometers offer several advantages over single-dish observations. The formalism for analyzing interferometer CMB data is well developed in the flat-sky approximation, which is valid for small fields of view. As the area of sky is increased to obtain finer spectral resolution, this approximation needs to be relaxed. We extend the formalism for

  20. CIST....CORRTEX interferometer simulation test

    SciTech Connect

    Heinle, R.A.

    1994-12-01

    Testing was performed in order to validate and cross calibrate an RF interferometer and the crush threshold of cable. Nitromethane was exploded (inside of PVC pipe). The explosion was used to crush the interferometer sensor cables which had been placed inside and outside the pipe. Results are described.

  1. FLUOR fibered instrument at the IOTA interferometer

    Microsoft Academic Search

    Vincent Coudé du Foresto; Guy Perrin; Cyril Ruilier; Bertrand P. Mennesson; Wesley A. Traub; Marc G. Lacasse

    1998-01-01

    The FLUOR project started in 1991 with a prototype fiber recombination unit that transformed a pair of independent 80 cm telescopes into a stellar interferometer. An improved version of this unit is now used as part of the instrumentation at the IOTA interferometer on Mt. Hopkins. The system is based on fluoride glass single-mode waveguides for observations at IR wavelengths

  2. The FLUOR\\/IOTA fiber stellar interferometer

    Microsoft Academic Search

    Vincent Coudé du Foresto; Guy Perrin; Jean-Marie Mariotti; Marc Lacasse; Wes Traub

    1997-01-01

    The FLUOR project started in 1991 with a prototype fiber recombination unit that transformed a pair of independent 80cm telescopes into a stellar interferometer. An improved version of this unit is now used as part of the instrumentation at the IOTA interferometer on Mt Hopkins (Arizona). The system is based on fluoride glass single- mode waveguides (non polarization-preserving) for observations

  3. Study Of Space-Based Optical Interferometer

    NASA Technical Reports Server (NTRS)

    Redding, David C.; Laskin, Robert A.; Breckenridge, William G.; Shao, Michael

    1992-01-01

    Report discusses calibration and operation of conceptual Focus Mission Interferometer (FMI), consisting of component instruments mounted at widely separated locations on large truss structure in orbit 1,400 km above Earth. Includes six telescopes in linear array. Outputs combined in pairlike fashion so FMI operates as three distinct two-telescope interferometers. Accurate enough for submilliarcsecond astrometry.

  4. AN ATOM INTERFEROMETER GYROSCOPE JAMES GREENBERG

    E-print Network

    Cronin, Alex D.

    AN ATOM INTERFEROMETER GYROSCOPE By JAMES GREENBERG A Thesis Submitted to the Honors College gyroscope that is sensitive to the abso- lute rotation rate of the lab with respect to an inertial frame. We accelerations of ±0.005g and absolute rotation rates of ±0.5E. Sensitive atom interferometer gyroscopes

  5. Use and Interpretation of Radar

    NSDL National Science Digital Library

    John Nielsen-Gammon

    1996-01-01

    This undergraduate meteorology tutorial from Texas A&M University discusses the basic principles of operation of weather radars, describes how to interpret radar mosaics, and discusses the use of radar in weather forecasting. Students learn the relationship between range and elevation and how to use radar images and mosaics in short-range forecasting.

  6. Ground-penetrating radar methods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ground-penetrating radar geophysical methods are finding greater and greater use in agriculture. With the ground-penetrating radar (GPR) method, an electromagnetic radio energy (radar) pulse is directed into the subsurface, followed by measurement of the elapsed time taken by the radar signal as it ...

  7. Radar remote sensing in biology

    USGS Publications Warehouse

    Moore, Richard K.; Simonett, David S.

    1967-01-01

    The present status of research on discrimination of natural and cultivated vegetation using radar imaging systems is sketched. The value of multiple polarization radar in improved discrimination of vegetation types over monoscopic radars is also documented. Possible future use of multi-frequency, multi-polarization radar systems for all weather agricultural survey is noted.

  8. Optimal interferometer designs for optical coherence tomography.

    PubMed

    Rollins, A M; Izatt, J A

    1999-11-01

    We introduce a family of power-conserving fiber-optic interferometer designs for low-coherence reflectometry that use optical circulators, unbalanced couplers, and (or) balanced heterodyne detection. Simple design equations for optimization of the signal-to-noise ratio of the interferometers are expressed in terms of relevant signal and noise sources and measurable system parameters. We use the equations to evaluate the expected performance of the new configurations compared with that of the standard Michelson interferometer that is commonly used in optical coherence tomography (OCT) systems. The analysis indicates that improved sensitivity is expected for all the new interferometer designs, compared with the sensitivity of the standard OCT interferometer, under high-speed imaging conditions. PMID:18079840

  9. Multi-instrument coordinated observations of auroral dynamics at EISCAT Svalbard and Sondrestrom Radar sites

    NASA Astrophysics Data System (ADS)

    Bhatt, A.; Stromme, A.; Häggström, I.; Samara, M.; Michell, R. G.; Labelle, J. W.; Broughton, M.; Lanchester, B. S.

    2011-12-01

    A multi-instrument campaign to observe auroral dynamics was conducted during February 7-10, 2011 at the EISCAT Svalbard Radar (ESR) in Norway and the Sondrestrom radar in Greenland. This campaign involved measurements of incoherent scatter spectra from both the radars, optical observations of aurora on both sites, and auroral radio emissions measured with a spectrum analyzer and with an LF/MF/HF interferometer at Sondrestrom. In this paper, we will present data from this coordinated study, focusing on correlations of plasma line enhancements and any NEIALs events with other datasets during auroral precipitation periods and substorm onsets. We will also present a comparative analysis of the same event reflected in two radars with very different wavelengths.

  10. Radar frequency radiation

    NASA Astrophysics Data System (ADS)

    Malowicki, E.

    1981-11-01

    A method is presented for the determination of radar frequency radiation power densities that the PAVE PAWS radar system could produce in its air and ground environment. The effort was prompted by the concern of the people in the vicinity of OTIS AFB MA and BEALE AFB CA about the possible radar frequency radiation hazard of the PAVE PAWS radar. The method is based on the following main assumptions that: (a) the total field can be computed as the vector summation of the individual fields due to each antenna element; (b) the individual field can be calculated using distances for which the field point is in the far field of the antenna element. An RFR computer program was coded for the RADC HE 6180 digital computer and exercised to calculate the radiation levels in the air and ground space for the present baseline and the possible Six DB and 10 DB growth systems of the PAVE PAWS radar system at OTIS AFB MA. The average radiation levels due to the surveillance fence were computed for three regions: in the air space in front of the radar, at the radar hazard fence at OTIS AFB MA and at representative ground points in the OTIS AFB vicinity. It was concluded that the radar frequency radiation of PAVE PAWS does not present a hazard to personnel provided there is no entry to the air hazard zone or to the area within the hazard fence. The method developed offers a cost effective way to determine radiation levels from a phased array radar especially in the near field and transition regions.

  11. Development of newly designed VHF interferometer system for observing earthquake-related atmospheric anomalies.

    PubMed

    Yamamoto, Isao; Fujiwara, Hironobu; Kamogawa, Masashi; Iyono, Atsushi; Kroumov, Valeri; Azakami, Takashi

    2009-01-01

    Temporal correlation between atmospheric anomalies and earthquakes has recently been verified statistically through measuring VHF FM radio waves transmitted beyond the line-of-sight. In order to locate the sources of such atmospheric anomalies, we developed a VHF interferometer system (bistatic-radar type) capable of finding the arrival direction of FM radio waves scattered possibly by earthquake-related atmospheric anomalies. In general, frequency modulation of FM radio waves produces ambiguity of arrival direction. However, our system, employing high-sampling rates of the order of kHz, can precisely measure the arrival direction of FM radio waves by stacking received signals. PMID:20009381

  12. Development of newly designed VHF interferometer system for observing earthquake-related atmospheric anomalies

    PubMed Central

    Yamamoto, Isao; Fujiwara, Hironobu; Kamogawa, Masashi; Iyono, Atsushi; Kroumov, Valeri; Azakami, Takashi

    2009-01-01

    Temporal correlation between atmospheric anomalies and earthquakes has recently been verified statistically through measuring VHF FM radio waves transmitted beyond the line-of-sight. In order to locate the sources of such atmospheric anomalies, we developed a VHF interferometer system (bistatic-radar type) capable of finding the arrival direction of FM radio waves scattered possibly by earthquake-related atmospheric anomalies. In general, frequency modulation of FM radio waves produces ambiguity of arrival direction. However, our system, employing high-sampling rates of the order of kHz, can precisely measure the arrival direction of FM radio waves by stacking received signals. PMID:20009381

  13. Spaceborne laser radar.

    PubMed

    Flom, T

    1972-02-01

    Laser radar systems are being developed to acquire and track targets in applications such as the rendezvous and docking of two spacecraft. To search effectively for and locate a target using a narrow laser beam, a scanning system is needed. This paper describes a scan technique whereby a narrow laser beam is synchronously scanned with an equally narrow receiver field-of-view without the aid of mechanical gimbals. Equations are developed in order to examine the maximum acquisition and tracking rates, and the maximum target range for a scanning laser radar system. A recently built prototype of a small, lightweight, low-power-consuming scanning laser radar is described. PMID:20111497

  14. Radar transmitter procedures

    NASA Astrophysics Data System (ADS)

    1993-03-01

    This ITOP outlines the test methods used in evaluating the performance and characteristics of general types of radar transmitters to include single or variable frequency transmitters. The test methods serve as a guide in determining the overall efficiency of such equipment as a function of their design and their recorded performance. This ITOP is limited to methods for measuring the performance of the radar transmitter under test as a major component. Some performance aspects of the transmitter can be tested only when configured as part of a total radar system.

  15. Sustained low efficiency dialysis using a single-pass batch system in acute kidney injury - a randomized interventional trial: the REnal Replacement Therapy Study in Intensive Care Unit PatiEnts

    PubMed Central

    2012-01-01

    Introduction Acute kidney injury (AKI) is associated with a high mortality of up to 60%. The mode of renal replacement therapy (intermittent versus continuous) has no impact on patient survival. Sustained low efficiency dialysis using a single-pass batch dialysis system (SLED-BD) has recently been introduced for the treatment of dialysis-dependent AKI. To date, however, only limited evidence is available in the comparison of SLED-BD versus continuous veno-venous hemofiltration (CVVH) in intensive care unit (ICU) patients with AKI. Methods Prospective, randomized, interventional, clinical study at a surgical intensive care unit of a university hospital. Between 1 April 2006 and 31 January 2009, 232 AKI patients who underwent renal replacement therapy (RRT) were randomized in the study. Follow-up was assessed until 30 August 2009. Patients were either assigned to 12-h SLED-BD or to 24-h predilutional CVVH. Both therapies were performed at a blood flow of 100 to 120 ml/min. Results 115 patients were treated with SLED-BD (total number of treatments n = 817) and 117 patients with CVVH (total number of treatments n = 877).The primary outcome measure, 90-day mortality, was similar between groups (SLED: 49.6% vs. CVVH: 55.6%, P = 0.43). Hemodynamic stability did not differ between SLED-BD and CVVH, whereas patients in the SLED-BD group had significantly fewer days of mechanical ventilation (17.7 ± 19.4 vs. 20.9 ± 19.8, P = 0.047) and fewer days in the ICU (19.6 ± 20.1 vs. 23.7 ± 21.9, P = 0.04). Patients treated with SLED needed fewer blood transfusions (1,375 ± 2,573 ml vs. 1,976 ± 3,316 ml, P = 0.02) and had a substantial reduction in nursing time spent for renal replacement therapy (P < 0.001) resulting in lower costs. Conclusions SLED-BD was associated with reduced nursing time and lower costs compared to CVVH at similar outcomes. In the light of limited health care resources, SLED-BD offers an attractive alternative for the treatment of AKI in ICU patients. Trial registration ClinicalTrials.gov NCT00322530 PMID:22839577

  16. X-ray shearing interferometer

    DOEpatents

    Koch, Jeffrey A. (Livermore, CA)

    2003-07-08

    An x-ray interferometer for analyzing high density plasmas and optically opaque materials includes a point-like x-ray source for providing a broadband x-ray source. The x-rays are directed through a target material and then are reflected by a high-quality ellipsoidally-bent imaging crystal to a diffraction grating disposed at 1.times. magnification. A spherically-bent imaging crystal is employed when the x-rays that are incident on the crystal surface are normal to that surface. The diffraction grating produces multiple beams which interfere with one another to produce an interference pattern which contains information about the target. A detector is disposed at the position of the image of the target produced by the interfering beams.

  17. Hubble Extra Solar Planet Interferometer

    NASA Technical Reports Server (NTRS)

    Shao, M.

    1991-01-01

    This paper describes a proposed third-generation Hubble instrument for extra-solar planet detection, the Hubble Extra-Solar Planet Interferometer (HESPI). This instrument would be able to achieve starlight cancellation at the 10 exp 6 to 10 exp 8 level, given a stellar wavefront with phase errors comparable to the present Hubble telescope wavefront. At 10 exp 6 starlight cancellation, HESPI would be able to detect a Jupiter-like planet next to a star at a distance of about 10 parsec, for which there are about 400 candidate stars. This paper describes a novel approach for starlight suppression, using a combination of active control and single-mode spatial filters, to achieve starlight suppression far below the classical limit set by scattering due to microsurface imperfections. In preliminary lab experiments, suppression by a factor of 40 below the classical scatter limit due to optical wavefront errors has been demonstrated.

  18. Radar - The Future

    NASA Astrophysics Data System (ADS)

    Warwick, G.

    1985-02-01

    Progress in civil and military radar units since the invention of radar in 1935 is summarized, noting the trend to multipurpose units. The earliest systems functioned at 10 cm, then 3 cm after development of a cavity magnetron to provide power for shorter wavelengths. Military needs are driving improvements in three-dimensional scanning capabilities, Primarily to locate aircraft in the presence of ground clutter and sea surface scattering. Autonomous, separate transmitter and receiver units are being tested. Lengthening ground-based radar wavelengths to tens of meters will permit over-the-horizon sensing with backscattering, ionospheric bounce, or induction of a potential in the sea surface as the possible techniques. Mode S monopulse radars will permit transponder queries between small and large aircraft. Finally, pulse Doppler SAR systems may afford terrain recognition with no corroborating data except an expert systems data base.

  19. Caribbean Radar Products

    NSDL National Science Digital Library

    2014-09-14

    This module provides examples of radar imagery from various locations in the Caribbean to demonstrate the different types of images available. Also, examples of different meteorological and non meteorological features are presented to show features seen in island locations.

  20. Millimeter Waves Ballistic Radar

    Microsoft Academic Search

    A. N. Zubkov; V. S. Gavrilov; Ya. M. Kempa; Z. V. Dufanets; N. A. Naumets

    2006-01-01

    Solid-state Doppler millimeter waves ballistic radar designed for measuring of exterior and interior ballistic parameters of highly dynamical faint objects is developed. The coherence characteristics of transmit-receive module are supported by the floating heterodyne oscillation behavior

  1. Fiber-optic coupled heterodyne interferometer

    NASA Astrophysics Data System (ADS)

    Zhang, Liang

    A lightweight and electrically passive interferometer is demanded by a number of applications for precision metrology such as machine tool metrology and on-machine feedback. To satisfy these requirements, a fiber-optic coupled heterodyne displacement measuring Michelson interferometer is developed. In this interferometer, the laser light is coupled into the interferometer with a polarization-maintaining (PM) fiber to separate the application environment of the interferometer from the laser head. The primary limitation of accuracy encountered with this fiber-optic coupled heterodyne interferometer is the optical mixing arising from the imperfection of fiber-optic coupling system. The optical mixing results in the nonlinearity (first order and second order errors) in the displacement measurement of the interferometer. Thermal translation is developed to measure the nonlinearity. A theoretical model using Jones calculus is developed and corresponding experiments are carried out with good agreement. A strategy of combined optical alignment and signal processing is determined to reduce nonlinearity below the level of 2 nm.

  2. Dispersion cancellation in a triple Laue interferometer

    NASA Astrophysics Data System (ADS)

    Lemmel, Hartmut

    2014-10-01

    The concept of dispersion cancellation has been established in light optics to improve the resolution of interferometric measurements on dispersive media. Odd order dispersion cancellation allows to measure phase shifts without defocusing the interferometer due to wave packet displacements, while even order dispersion cancellation allows to measure time lags without losing resolution due to wave packet spreading. We report that either type of dispersion cancellation can be realized very easily in a triple Laue interferometer. Such interferometers are Mach-Zehnder interferometers based on Bragg diffraction, and are commonly used for neutrons and x-rays. Although the first x-ray interferometer was built nearly five decades ago, the feature of dispersion cancellation hasn't been recognized so far because the concept was hardly known in the neutron and x-ray community. However, it explains right away the surprising decoupling of phase shift and spatial displacement that we have discovered recently in neutron interferometry (Lemmel and Wagh 2010 Phys. Rev. A 82 033626). Furthermore, this article might inspire the light optics community to consider whether a triple Laue interferometer for laser light would be useful and feasible. We explain how dispersion cancellation works in neutron interferometry, and we describe the setup rigorously by solving the Schrödinger equation and by calculating the path integral. We point out, that the latter has to be evaluated with special care since in our setup the beam trajectory moves with respect to the crystal lattice of the interferometer.

  3. Active radar stealth device

    NASA Astrophysics Data System (ADS)

    Cain, R. N.; Corda, Albert J.

    1991-07-01

    This patent discloses an active radar stealth device mounted on a host platform for minimizing the radar cross-section of the host platform. A coating which is essentially microwave transparent is attached to the surface of a host platform and is exposed to an incident microwave field. A plurality of detector/emitter pairs contained within the coating detect and actively cancel, respectively, the microwave field at each respective detector/emitter pair.

  4. Cassini Radar hardware technologies

    SciTech Connect

    Wheeler, K.; Renick, P. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)

    1996-03-01

    The hardware development portion of the Cassini Radar task is complete. The flight model Digital Assembly and Energy Storage Assembly have been integrated and tested, as has the engineering/qualification model Radio Frequency Electronics Assembly. Integration of the flight model Radio Frequency Electronics Assembly is ready to begin. The intent of this paper is to describe some of the more interesting technologies implemented in the electronics to achieve the requirements of the Cassini Radar experiment. {copyright} {ital 1996 American Institute of Physics.}

  5. Phased-array radars

    NASA Astrophysics Data System (ADS)

    Brookner, E.

    1985-02-01

    The operating principles, technology, and applications of phased-array radars are reviewed and illustrated with diagrams and photographs. Consideration is given to the antenna elements, circuitry for time delays, phase shifters, pulse coding and compression, and hybrid radars combining phased arrays with lenses to alter the beam characteristics. The capabilities and typical hardware of phased arrays are shown using the US military systems COBRA DANE and PAVE PAWS as examples.

  6. Multiresolution GMTI radar

    Microsoft Academic Search

    J. R. Guerci; A. O. Steinhardt

    2003-01-01

    The detection and tracking of ground moving vehicles from airborne radar can be challenging at slow target velocities due to the close space-time (angle-Doppler) proximity of strong competing mainbeam clutter. Moreover, in complex non-stationary clutter environments, conventional space-time adaptive processing (STAP) cannot be relied upon to provide precision ing. In this paper, we re-examine GMTI radar from a multiresolution perspective

  7. Weather Radar Network Design

    Microsoft Academic Search

    Francesc Junyent; V. Chandrasekar

    2008-01-01

    The Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) is investigating the use of dense networks of short-range radars for weather sensing. A first test-bed of this new paradigm is currently deployed in southwest Oklahoma. The potential benefits of closely deployed, overlapping, short-range weather radars are easy to see intuitively amounting to a greater ability to measure

  8. Terminal Doppler weather radar

    Microsoft Academic Search

    M. Michelson; W. W. Shrader; J. G. Wieler

    1990-01-01

    The terminal Doppler weather radar (TDWR) system, now under development, will provide automatic detection of microbursts and low-level wind shear. This paper discusses the TDWR performance parameters and describes its structural elements, including the antenna subsystem, the transmitter, the receiver\\/exciter, the digital signal processor, and the radar product generator\\/remote monitoring subsystem. Attention is also given to the processes of the

  9. Doppler Radar Technology

    NSDL National Science Digital Library

    This resource provides an introduction to the function and uses of the The National Weather Service's (NWS) Weather Surveillance Doppler Radar (WSR-88D). Topics include the components of the system, an overview of the products and overlays the system creates, and some example images with captions explaining what is being shown. There are also links to radar meteorology tutorials and to information on training to use the system and interpret its imagery.

  10. Radar network characterization

    Microsoft Academic Search

    Francesc Junyent; V. Chandrasekar

    2007-01-01

    The use of dense networks of small radars for weather sensing is being investigated by the Engineering Research Center for Collaborative Adaptive Sensing of the Atmosphere, with a first test-bed of this new paradigm well underway. The potential benefits of closely-deployed, overlapping, short-range weather radars are easy to see intuitively, and can be summarized as a greater ability to mitigate

  11. Slow wave atom interferometers for rotation sensing

    NASA Astrophysics Data System (ADS)

    Özcan, Meriç

    2007-02-01

    A gyroscope based on Sagnac interferometer measures the rotation rate relative to an inertial frame of reference. Sagnac effect originally has been derived and experimentally demonstrated with optical waves. Later, matter wave based Sagnac interferometers were developed due to inherent sensitivity over a photon based system. However in any interferometer whether it is photon or matter wave based the resultant phase shift due to counter-rotating waves is independent of the wave velocity. Here we show that one can have a larger phase shift with slower matter waves using Aharonov-Bohm effect: the phase difference of the counter propagating waves is proportional to the inverse square of the particle velocity.

  12. Active noise cancellation in a suspended interferometer

    E-print Network

    Jennifer C. Driggers; Matthew Evans; Keenan Pepper; Rana Adhikari

    2011-12-09

    We demonstrate feed-forward vibration isolation on a suspended Fabry-Perot interferometer using Wiener filtering and a variant of the common Least Mean Square (LMS) adaptive filter algorithm. We compare the experimental results with theoretical estimates of the cancellation efficiency. Using data from the recent LIGO Science Run, we also estimate the impact of this technique on full scale gravitational wave interferometers. In the future, we expect to use this technique to also remove acoustic, magnetic, and gravitational noise perturbations from the LIGO interferometers. This noise cancellation technique is simple enough to implement in standard laboratory environments and can be used to improve SNR for a variety of high precision experiments.

  13. X-ray Interferometer Using Prism Optics

    SciTech Connect

    Suzuki, Yoshio [JASRI/SPring-8 Mikazuki, Hyogo 6791-5198 (Japan)

    2004-05-12

    Two-beam X-ray interferometer using refractive optics has been developed. A prism made of acrylic resin is used as the beam deflector for hard X-ray wavefront dividing interferometer. This configuration is the same as that of the Fresnel's bi-prism interferometer or the Leith-Upatnieks type two-beam holography in visible light region. Therefore, quantitative analysis of the degree of transversal coherence can be performed by measuring the visibility of interference fringes. It is also possible to realize two-beam holographic imaging in hard X-ray regions.

  14. A compact, robust and versatile moiré interferometer

    NASA Astrophysics Data System (ADS)

    Mollenhauer, D. H.; Ifju, P. G.; Han, B.

    A moiré interferometer was designed and constructed based on a general system design using a reflective crossed-line diffraction grating to produce the four beams of light necessary for moiré interferometry. The design concept, basic design and tuning procedures are discussed. The important features of the interferometer, i.e. compactness, versatility, polarization insensitivity, relaxed collimation requirements, low laser power and remote optics, are addressed. Several such interferometers have been constructed and successfully applied to engineering problems. These include examining the displacement fields surrounding drilled and preformed holes in composite laminates loaded in tension, and the evaluation of nonhomogeneous behavior in textile composites.

  15. The microwave interferometer on J-TEXT tokamak

    Microsoft Academic Search

    L. Gao; G. Zhuang; X. W. Hu; Z. J. Yang

    2008-01-01

    A 2 mm microwave interferometer is developed to measure plasma electron density for the J-TEXT tokamak. The interferometer views the plasma vertically through a set of large diagnostic ports and the system is configured as a frequency-modulated interferometer. The interferometer routinely provides real-time feedback control for the gas injection system.

  16. Overview of the control system for the Keck Interferometer

    Microsoft Academic Search

    Andrew J. Booth; Glenn Eychaner; Erik Hovland; Richard L. Johnson Jr.; William Lupton; Al Niessner; Dean L. Palmer; Leonard J. Reder; Andy C. Rudeen; Robert F. Smythe; Kevin Tsubota

    2002-01-01

    The Keck Interferometer links the two 10m Keck Telescopes located atop Mauna Kea in Hawaii. It is the first 10m class, fully AO equipped interferometer to enter operation. Further, it is the first large interferometer designed to be handed over from a design and implementation team to a separate operations team, and be used by astronomers who are not interferometer

  17. Radar MeteorologyRadar Meteorology Feb 20, 1941 10 cm (S-band) radar used to track rain showers (Ligda)

    E-print Network

    Rutledge, Steven

    Radar MeteorologyRadar Meteorology Feb 20, 1941 10 cm (S-band) radar used to track rain showers similar observations in the early 1940's (U.S. Air Corps meteorologists receiving "radar" training at MIT in 1943 First operational weather radar, Panama, 1943 Science of radar meteorology born from WWII research

  18. Analysis of phase relationships between radar signals in acoustooptic processing systems

    Microsoft Academic Search

    M. V. D’yakonov; T. F. Faîsullov; T. T. Sultanov; A. F. Tavasiev; A. N. Torgashin; V. A. Zubov

    1997-01-01

    The performance and the salient operation features of an interference correlator with a modified optical twin-wave Rayleigh\\u000a interferometer system in the mode of measurements of phase shifts between radar signals are considered. Such measurements\\u000a for signals received from two antennas provide information on the angular position of an object or its displacement. A system\\u000a wherein radio signals are fed for

  19. Fiber optics speckle interferometer for diffusivity measurements

    Microsoft Academic Search

    D. Paoletti; G. Schirripa Spagnolo

    1993-01-01

    A digital speckle pattern interferometer with optical fibers is proposed for the real time measurement of the diffusion coefficient of liquid binary mixtures. Some examples of application of the technique are reported.

  20. Atom Interferometers with Scalable Enclosed Area

    SciTech Connect

    Mueller, Holger; Chu, Steven [Department of Physics, 366 Le Conte Hall, University of California, Berkeley, California 94720-7300 (United States); Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720 (United States); Chiow, Sheng-wey; Herrmann, Sven [Physics Department, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305 (United States)

    2009-06-19

    Bloch oscillations (i.e., coherent acceleration of matter waves by an optical lattice) and Bragg diffraction are integrated into light-pulse atom interferometers with large momentum splitting between the interferometer arms, and hence enhanced sensitivity. Simultaneous acceleration of both arms in the same internal states suppresses systematic effects, and simultaneously running a pair of interferometers suppresses the effect of vibrations. Ramsey-Borde interferometers using four such Bloch-Bragg-Bloch beam splitters exhibit 15% contrast at 24(Planck constant/2pi)k splitting, the largest so far ((Planck constant/2pi)k is the photon momentum); single beam splitters achieve 88(Planck constant/2pi)k. The prospects for reaching 100 s of (Planck constant/2pi)k and applications such as gravitational wave sensors are discussed.

  1. Polymeric slot waveguide interferometer for sensor applications.

    PubMed

    Hiltunen, Marianne; Hiltunen, Jussi; Stenberg, Petri; Aikio, Sanna; Kurki, Lauri; Vahimaa, Pasi; Karioja, Pentti

    2014-03-24

    A refractive index sensor based on slot waveguide Young interferometer was developed in this work. The interferometer was fabricated on a polymer platform and operates at a visible wavelength of 633 nm. The phase shift of the interference pattern was measured with various concentrations of glucose-water solutions, utilizing both TE and TM polarization states. The sensor was experimentally observed to detect a refractive index difference of 6.4 × 10(-6) RIU. Furthermore, the slot Young interferometer was found to compensate for temperature variations. The results of this work demonstrate that high performance sensing capability can be obtained with a polymeric slot Young interferometer, which can be fabricated by a simple molding process. PMID:24664071

  2. Temperature compensated two-mode fiber interferometer 

    E-print Network

    Doma, Jagdish Ramchandra

    1993-01-01

    In this thesis we propose an innovative approach of designing and implementing a temperature compensated two-mode optical fiber interferometer in a control system of stabilizing the wavelength of a laser. We give the procedure for designing...

  3. Direct reading fast microwave interferometer for EBT

    SciTech Connect

    Uckan, T.

    1984-10-01

    A simple and inexpensive 4-mm direct reading fast (rise time approx. 100 ..mu..s) microwave interferometer is described. The system is particularly useful for density measurements on the ELMO Bumpy Torus (EBT) during pulsed operation.

  4. Polarization phase shifting lateral shearing interferometer

    NASA Astrophysics Data System (ADS)

    Liu, Lei; Zeng, Aijun; Zhu, Linglin; Song, Qiang; Huang, Huijie

    2013-08-01

    A polarization phase shifting lateral shearing interferometer based on a polarization beam splitting plate(PBSP) is proposed. The front surface of the PBSP is coated with polarization beam splitting film and its back surface is coated with total reflection film. The beam to be tested is split by the PBSP with an incidence angle of 45° and divided into two mutually perpendicular linearly polarization beams. Phase shifting can be introduced to the interferometer when the PBSP is combined with a polarzation temporal or spatial phase shifter. A polarizaiton temporal phase shifting lateral shearing interferometer system is built up both with the ASAP software and the experiments. The usefulness of the interferometer is verified.

  5. The effect of rotations on Michelson interferometers

    NASA Astrophysics Data System (ADS)

    Maraner, Paolo

    2014-11-01

    In the contest of the special theory of relativity, it is shown that uniform rotations induce a phase shift in Michelson interferometers. The effect is second order in the ratio of the interferometer's speed to the speed of light, further suppressed by the ratio of the interferometer's arms length to the radius of rotation and depends on the interferometer's position in the co-rotating frame. The magnitude of the phase shift is just beyond the sensitivity of turntable rotated optical resonators used in present tests of Lorentz invariance. It grows significantly large in Earth's rotated kilometer-scale Fabry-Perot enhanced interferometric gravitational-wave detectors where it appears as a constant bias. The effect can provide the means of sensing center and radius of rotations.

  6. Versatility of the vectorial shearing interferometer

    NASA Astrophysics Data System (ADS)

    Paez, Gonzalo; Strojnik, Marija

    2002-02-01

    Recently, we developed a new type of a shearing interferometer, based on the Mach-Zehnder configuration, except that a beam director is incorporated in one arm of the interferometer and a compensator in the other one. The wave-front displacement is accomplished upon the angle setting between two Risley prisms. With the control of this angle, wave-front displacements are effectuated such that large and small aberrations may be measured with the same instrument. The vectorial shearing interferometer allows the optimization of the measurement parameters tailored to the specific application and the possible absence of available references. We present several applications of the vectorial shearing interferometer to the optical testing and the alignment of the optical systems.

  7. The VLA Atmospheric Phase Interferometer

    NASA Astrophysics Data System (ADS)

    Morris, Keith

    2014-05-01

    The Atmospheric Phase Interferometer (API) is a two-element atmospheric seeing monitor located at the Very Large Array (VLA) site. The instrument measures turbulent refractive index variation through the atmosphere by examining phase differences in a satellite beacon signal detected at two (or more) antennas. With this measurement, the VLA scheduling software is able to consider atmospheric stability when determining which frequency observation to schedule next. We are in the process of extending this two-element interferometer to four elements, which will allow us to measure the turbulence in two dimensions and at multiple length scales. This thesis will look at some statistical properties of turbulence, the effects of atmospheric stability on radio interferometric observations, and discuss details of the instrument and the data that it collects. The thesis will also cover some techniques and principles of signal processing, and an analysis of some data from the instrument. The results demonstrate that other surface atmospheric variables (e.g. windspeed, water vapor pressure) show the same structure function exponent as the atmospheric phase fluctuations. In particular, the structure functions of water vapor partial pressure and wind speed show the same exponent as the phase. Though the agreement between meteorological variables and atmospheric phase is scientifically satisfying, these surface measurements are not nearly as sensitive as the API saturation phase measurement, and therefore cannot be used to schedule telescope time in its stead. What is informative about these results is that the similar structure functions for API and meteorological data are detecting reinforce the claim that both measurements represent turbulent transport, and not instrumental noise. Data from the instrument reveals that measurements are consistent with both Kolmogorov turbulence theory, and with prior observations. The API predominately measures three-dimensional isotropic turbulence, but is capable of seeing the transition to two-dimensional "thin screen" turbulence. There is evidence that water vapor scale height can be estimated from the API data. We can expect to be able measure and document variations in the water vapor scale height by looking at variation of structure function exponents. Once the reliability of the method is established, a series of altitude profiles could allow further validation of this method of scale height determination. We look at a method for statistical excision of instrumental noise from the data. The ability to discriminate noise from signal based on structure function exponent leads to a path to possible noise elimination techniques. With the redundant measurement baselines of the new API, experimental processing techniques such as this could be deployed on some baselines, but not others, leaving the production functions for VLA scheduling in a known state while allowing instrument improvement studies to proceed.

  8. In-Line Sagnac Interferometer Current Sensor

    Microsoft Academic Search

    Prinya Tantaswadi

    1995-01-01

    We demonstrate for the first time a near shot noise limited in-line Sagnac interferometer current sensor. It is shown to have a number of advantages over the optical current sensors based on polarimetric Faraday and Faraday\\/Sagnac loop interferometer topologies, including lower sensitivity to environmental disturbances, less demanding optical components, and easy installation. Our contributions to the field of fiber-optic current

  9. Microwave interferometer techniques for detonation study

    SciTech Connect

    Stanton, P.L.; Venturini, E.L.; Dietzel, R.W.

    1985-01-01

    Techniques have been developed to improve resolution in microwave interferometry of detonating explosives. Unwanted reflections in the measurement arm of the interferometer result in phase distortion of the recorded signal. By using tuning techniques, unwanted reflections can be virtually eliminated, and phase distortion is minimized, for some experimental conditions. The use of a quadrature detector and an intensity monitor also improve the resolution of the interferometer. Data obtained in several detonation experiments are presented and interpreted. 13 refs., 7 figs.

  10. Dual-beam skin friction interferometer

    NASA Technical Reports Server (NTRS)

    Monson, D. J. (inventor)

    1981-01-01

    A portable dual-laser beam interferometer is described that nonintrusively measures skin friction by monitoring the thickness change of an oil film at two locations while said oil film is subjected to shear stress. An interferometer flat is utilized to develop the two beams. Light detectors sense the beam reflections from the oil film and the surface thereunder. The signals from the detectors are recorded so that the number of interference fringes produced over a given time span may be counted.

  11. Nonlinear Michelson interferometer for improved quantum metrology

    E-print Network

    Alfredo Luis; Ángel Rivas

    2015-04-21

    We examine nonlinear quantum detection via a Michelson interferometer embedded in a gas with Kerr nonlinearity. The interferometer is illuminated by pulses of classical light. This strategy combines the robustness against practical imperfections of classical light with the improvement provided by nonlinear detection. Regarding ultimate quantum limits, we stress that, as a difference with linear schemes, the nonlinearity introduces pulse duration as a new variable into play along with the energy resources.

  12. Recent progress at the Keck Interferometer

    Microsoft Academic Search

    S. Ragland; R. Akeson; M. Colavita; R. Millan-Gabet; J. Woillez; P. Wizinowich; E. Appleby; B. Berkey; A. Cooper; C. Felizardo; J. Herstein; M. Hrynevych; D. Medeiros; D. Morrison; T. Panteleeva; J.-U. Pott; B. Smith; K. Summers; K. Tsubota; C. Tyau; E. Wetherell

    2010-01-01

    The Keck Interferometer (KI) combines the two 10m diameter Keck telescopes providing milliarcsecond angular resolution. KI has unique observing capabilities such as sensitive K-band V2, L-band V2 and N-band nulling operations. The instrument status of the Keck Interferometer since the last SPIE meeting in 2008 is summarized. We discuss the performance of new visibility observing capabilities including L-band and self-phase

  13. Weather Radar and Instrumentation: Laboratory Modules

    NSDL National Science Digital Library

    These 16 radar education modules, developed for the Weather Radar and Instrumentation Curriculum at the University of Oklahoma, provide hands-on instruction for beginning, intermediate, or advanced students to learn about radar systems, especially weather radar. Topics include hardware, weather radar, adaptive systems, advanced hydrometeors, applications of weather radar, and atmospheric interpretations. The modules may be downloaded.

  14. Microphysical cross validation of spaceborne radar and ground polarimetric radar

    Microsoft Academic Search

    V. Chandrasekar; Steven M. Bolen; Eugenio Gorgucci

    2003-01-01

    Ground-based polarimetric radar observations along the beam path of the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), matched in resolution volume and aligned to PR measurements, are used to estimate the parameters of a gamma raindrop size distribution (RSD) model along the radar beam in the presence of rain. The PR operates at 13.8 GHz, and its signal returns

  15. RADAR: THE CASSINI TITAN RADAR MAPPER C. ELACHI1,

    E-print Network

    RADAR: THE CASSINI TITAN RADAR MAPPER C. ELACHI1, , M. D. ALLISON2 , L. BORGARELLI3 , P. ENCRENAZ4; Accepted in final form 3 June 1999) Abstract. The Cassini RADAR instrument is a multimode 13.8 GHz multiple coefficient as low as -40 dB. 1. Introduction The Cassini spacecraft, launched on October 15, 1997, carries

  16. Minimum radar cross section bounds for passive radar responsive tags

    Microsoft Academic Search

    P. Bidigare; T. Stevens; B Correll; M. Beauvais

    2004-01-01

    A common problem in ground moving target indication (GMTI) radar is detecting a target with even a large radar cross section (RCS) when its line-of-sight velocity falls below the minimum detectable velocity (MDV) for that radar system. In a cooperative scenario, a target may employ a tagging device, which can shift or spread its Doppler signature to become more detectable.

  17. Achromatic self-referencing interferometer

    DOEpatents

    Feldman, M.

    1994-04-19

    A self-referencing Mach-Zehnder interferometer is described for accurately measuring laser wavefronts over a broad wavelength range (for example, 600 nm to 900 nm). The apparatus directs a reference portion of an input beam to a reference arm and a measurement portion of the input beam to a measurement arm, recombines the output beams from the reference and measurement arms, and registers the resulting interference pattern ([open quotes]first[close quotes] interferogram) at a first detector. Optionally, subportions of the measurement portion are diverted to second and third detectors, which respectively register intensity and interferogram signals which can be processed to reduce the first interferogram's sensitivity to input noise. The reference arm includes a spatial filter producing a high quality spherical beam from the reference portion, a tilted wedge plate compensating for off-axis aberrations in the spatial filter output, and mirror collimating the radiation transmitted through the tilted wedge plate. The apparatus includes a thermally and mechanically stable baseplate which supports all reference arm optics, or at least the spatial filter, tilted wedge plate, and the collimator. The tilted wedge plate is mounted adjustably with respect to the spatial filter and collimator, so that it can be maintained in an orientation in which it does not introduce significant wave front errors into the beam propagating through the reference arm. The apparatus is polarization insensitive and has an equal path length configuration enabling measurement of radiation from broadband as well as closely spaced laser line sources. 3 figures.

  18. Microwave emissions from police radar 

    E-print Network

    Fink, John Michael

    1994-01-01

    The purpose of this study was to evaluate police officers exposures to microwaves emitted by traffic radar units at the ocular and testicular level. Additionally, comparisons were made of the radar manufacturers published maximum power density...

  19. Venus wind-altitude radar

    NASA Technical Reports Server (NTRS)

    Levanon, N.

    1974-01-01

    A design study on adding a radar altimeter to the Pioneer Venus small probe is review. Block and timing diagrams are provided. The inherent and interface ambiguities, resolution, and data handling logic for radar altimeters are described.

  20. Systems and Methods for Radar Data Communication

    NASA Technical Reports Server (NTRS)

    Bunch, Brian (Inventor); Szeto, Roland (Inventor); Miller, Brad (Inventor)

    2013-01-01

    A radar information processing system is operable to process high bandwidth radar information received from a radar system into low bandwidth radar information that may be communicated to a low bandwidth connection coupled to an electronic flight bag (EFB). An exemplary embodiment receives radar information from a radar system, the radar information communicated from the radar system at a first bandwidth; processes the received radar information into processed radar information, the processed radar information configured for communication over a connection operable at a second bandwidth, the second bandwidth lower than the first bandwidth; and communicates the radar information from a radar system, the radar information communicated from the radar system at a first bandwidth.

  1. A review of array radars

    Microsoft Academic Search

    E. Brookner

    1981-01-01

    Achievements in the area of array radars are illustrated by such activities as the operational deployment of the large high-power, high-range-resolution Cobra Dane; the operational deployment of two all-solid-state high-power, large UHF Pave Paws radars; and the development of the SAM multifunction Patriot radar. This paper reviews the following topics: array radars steered in azimuth and elevation by phase shifting

  2. Radar sector blanker

    NASA Astrophysics Data System (ADS)

    Hall, Roger B.

    1994-03-01

    A radar sector blanker comprises in analog-to-digital converter and a sector controller unit. The analog-to-digital converter receives the analog synchro voltages describing the positioning of a radar antenna and changes these voltages into binary-coded decimal (BCD) information. The sector controller unit comprises a portable housing, a controller system, and a power supply. The controller system includes an OFF comparator circuit, an ON comparator circuit, an S-R latch, and a solid-state switch. Each comparator circuit comprises three cascaded transistor-transistor logic (TTL) integrated chips. The power supply gives a direct-current voltage to the solid-state switch and the TTL chips. The sector blanker blocks transmission for a predetermined rotational region or sector of a radar system.

  3. The Clementine Bistatic Radar Experiment

    Microsoft Academic Search

    S. Nozette; C. L. Lichtenberg; P. Spudis; R. Bonner; W. Ort; E. Malaret; M. Robinson; E. M. Shoemaker

    1996-01-01

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar

  4. The Shuttle Radar Topography Mission

    Microsoft Academic Search

    Tom G. Farr; Paul A. Rosen; Edward Caro; Robert Crippen; Riley Duren; Scott Hensley; Michael Kobrick; Mimi Paller; Ernesto Rodriguez; Ladislav Roth; David Seal; Scott Shaffer; Joanne Shimada; Jeffrey Umland; Marian Werner; Michael Oskin; Douglas Burbank; Douglas Alsdorf

    2007-01-01

    The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth. The project was a joint endeavor of NASA, the National Geospatial-Intelligence Agency, and the German and Italian Space Agencies and flew in February 2000. It used dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution.

  5. Target identification from radar signatures

    Microsoft Academic Search

    R. Strattan

    1978-01-01

    Modern high resolution radar techniques and real time digital signal processing advances indicate the feasibility of extracting characteristic features of aircraft targets from their radar signatures. Two basic approaches have been suggested. The low frequency approach utilizes harmonically related radar frequencies with wavelengths comparable to the target dimensions. The microwave approach utilizes spread spectrum techniques to achieve high range resolution.

  6. SEASAT Synthetic Aperture Radar Data

    NASA Technical Reports Server (NTRS)

    Henderson, F. M.

    1981-01-01

    The potential of radar imagery from space altitudes is discussed and the advantages of radar over passive sensor systems are outlined. Specific reference is made to the SEASAT synthetic aperture radar. Possible applications include oil spill monitoring, snow and ice reconnaissance, mineral exploration, and monitoring phenomena in the urban environment.

  7. Review of current radar interests

    Microsoft Academic Search

    M. I. Skolnik

    1974-01-01

    Current radar applications and problem areas are reviewed. Air traffic control, aircraft and ship navigation, remote sensing, and law enforcement are some of the applications mentioned. Both the Gemini and the Apollo space vehicles used radar for rendezvous and docking, and Apollo also utilized it for lunar landing. Equipment improvements suggested include better isolation in CW radar, efficient linear transmitters,

  8. A radar tour of Venus

    Microsoft Academic Search

    J. K. Beatty

    1985-01-01

    The surface of Venus is briefly characterized in a summary of results obtained by the Soviet Venera 15 and 16 8-cm synthetic-aperture radars, IR radiometers, and radar altimeters. A series of radar images, mainly from Kotelnikov et al. (1984), are presented and discussed, and the descent vehicles to be released by the two Vega spacecraft as they pass Venus in

  9. Analysis of Random Radar Networks

    E-print Network

    Adve, Raviraj

    a design tradeoff between spatial diversity and interference cancellation for multistatic radar networksAnalysis of Random Radar Networks Rani Daher, Raviraj Adve Department of Electrical and Computer.daher@utoronto.ca, rsadve@comm.utoronto.ca Abstract--We introduce the notion of random radar networks to analyze the effect

  10. Analysis of weather radar return

    Microsoft Academic Search

    D. Payne

    1977-01-01

    A mathematical model of detected clutter from an airborne weather radar of conventional design is developed. The model is the joint probability density of samples of radar return from hydrometeors at the same nominal range and scan angle. It is developed from analysis of the effect on the received signal of the following parameters: inhomogeneous hydrometeor motion, radar frequency stability,

  11. Spaceborne Imaging Radar Symposium

    NASA Technical Reports Server (NTRS)

    Elachi, C.

    1983-01-01

    An overview of the present state of the art in the different scientific and technological fields related to spaceborne imaging radars was presented. The data acquired with the SEASAT SAR (1978) and Shuttle Imaging Radar, SIR-A (1981) clearly demonstrated the important emphasis in the 80's is going to be on in-depth research investigations conducted with the more flexible and sophisticated SIR series instruments and on long term monitoring of geophysical phenomena conducted from free-flying platforms such as ERS-1 and RADARSAT.

  12. Spaceborne laser radar.

    NASA Technical Reports Server (NTRS)

    Flom, T.

    1972-01-01

    Development of laser systems to acquire and track targets in applications such as the rendezvous and docking of two spacecraft. A scan technique is described whereby a narrow laser beam is simultaneously scanned with an equally narrow receiver field-of-view without the aid of mechanical gimbals. Equations are developed in order to examine the maximum acquisition and tracking rates, and the maximum target range for a scanning laser radar system. A recently built prototype of a small, lightweight, low-power-consuming scanning laser radar is described.

  13. Microwave radar oceanographic investigations

    NASA Technical Reports Server (NTRS)

    Jackson, F. C.

    1988-01-01

    The Radar Ocean Wave Spectrometer (ROWS) technique was developed and demonstrated for measuring ocean wave directional spectra from air and space platforms. The measurement technique was well demonstrated with data collected in a number of flight experiments involving wave spectral comparisons with wave buoys and the Surface Contour Radar (SCR). Recent missions include the SIR-B underflight experiment (1984), FASINEX (1986), and LEWEX (1987). ROWS related activity is presently concentrating on using the aircraft instrument for wave-processes investigations and obtaining the necessary support (consensus) for a satellite instrument development program. Prospective platforms include EOS and the Canadian RADARSAT.

  14. Radar Investigations of Asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1984-01-01

    Radar investigations of asteroids, including observations during 1984 to 1985 of at least 8 potential targets and continued analyses of radar data obtained during 1980 to 1984 for 30 other asteroids is proposed. The primary scientific objectives include estimation of echo strength, polarization, spectral shape, spectral bandwidth, and Doppler shift. These measurements yield estimates of target size, shape, and spin vector; place constraints on topography, morphology, density, and composition of the planetary surface; yield refined estimates of target orbital parameters; and reveals the presence of asteroidal satellites.

  15. Comparison of Atom Interferometers and Light Interferometers as Space-Based Gravitational Wave Detectors

    E-print Network

    John G. Baker; James Ira Thorpe

    2012-01-26

    We consider a class of proposed gravitational wave detectors based on multiple atomic interferometers separated by large baselines and referenced by common laser systems. We compute the sensitivity limits of these detectors due to intrinsic phase noise of the light sources, non-inertial motion of the light sources, and atomic shot noise and compare them to sensitivity limits for traditional light interferometers. We find that atom interferometers and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g. multiple arm instruments) to reach interesting sensitivities. The sensitivity limit from motion of the light sources is slightly different and favors the atom interferometers in the low-frequency limit, although the limit in both cases is severe.

  16. Prospects for a Gradient Magnetometer Atom Interferometer

    NASA Astrophysics Data System (ADS)

    Narducci, Frank A.; Davis, Jon P.

    2008-03-01

    Atom interferometers form the basis for state-of-the-art sensors, including gravimeters, gravity gradiometers, gyroscopes and atomic clocks. Notably absent from this list are magnetometers, which can have a wide range of applications ranging from military to medical applications. We propose a scheme to realize an atom interferometer gradient magnetometer. We begin by demonstrating a light-pulse magnetic beam-splitter. The analysis is based on a full multi-level 2-laser field Maxwell-Bloch model including state selection rules, polarization selectivity, laser detuning, and Doppler averaging. We then consider an ensemble of atoms subject to a ?/2-?-?/2 pulse sequence. The phase of the interference pattern depends on the phase of the action along the classical path and on the phase of the combined laser fields imprinted on the atoms during the pulse sequence. From this analysis, we conclude that, to first order, the phase of the interferometer output is insensitive to the field across the interferometer, but is sensitive to the gradient of the field. Using realizable numbers from existing interferometers, we show that a gradient magnetometer of this type has can have a greater gradient sensitivity than many current magnetic sensors. We discuss the status of our current experiments using ultra-cold atoms.

  17. Miniaturized Ka-Band Dual-Channel Radar

    NASA Technical Reports Server (NTRS)

    Hoffman, James P.; Moussessian, Alina; Jenabi, Masud; Custodero, Brian

    2011-01-01

    Smaller (volume, mass, power) electronics for a Ka-band (36 GHz) radar interferometer were required. To reduce size and achieve better control over RFphase versus temperature, fully hybrid electronics were developed for the RF portion of the radar s two-channel receiver and single-channel transmitter. In this context, fully hybrid means that every active RF device was an open die, and all passives were directly attached to the subcarrier. Attachments were made using wire and ribbon bonding. In this way, every component, even small passives, was selected for the fabrication of the two radar receivers, and the devices were mounted relative to each other in order to make complementary components isothermal and to isolate other components from potential temperature gradients. This is critical for developing receivers that can track each other s phase over temperature, which is a key mission driver for obtaining ocean surface height. Fully hybrid, Ka-band (36 GHz) radar transmitter and dual-channel receiver were developed for spaceborne radar interferometry. The fully hybrid fabrication enables control over every aspect of the component selection, placement, and connection. Since the two receiver channels must track each other to better than 100 millidegrees of RF phase over several minutes, the hardware in the two receivers must be "identical," routed the same (same line lengths), and as isothermal as possible. This level of design freedom is not possible with packaged components, which include many internal passive, unknown internal connection lengths/types, and often a single orientation of inputs and outputs.

  18. A Software Tool for Processing the Displacement Time Series Extracted from Raw Radar Data

    NASA Astrophysics Data System (ADS)

    Coppi, Francesco; Gentile, Carmelo; Paolo Ricci, Pier

    2010-05-01

    The application of high-resolution radar waveform and interferometric principles recently led to the development of a microwave interferometer, suitable to simultaneously measuring the (static or dynamic) deflection of several points on a large structure. From the technical standpoint, the sensor is a Stepped Frequency Continuous Wave (SF-CW), coherent radar, operating in the Ku frequency band. In the paper, the main procedures adopted to extract the deflection time series from raw radar data and to assess the quality of data are addressed, and the MATLAB toolbox developed is described. Subsequently, other functions implemented in the software tool (e.g. evaluation of the spectral matrix of the deflection time-histories, identification of natural frequencies and operational mode shapes evaluation) are described and the application to data recorded on full-scale bridges is exemplified.

  19. Bistatic synthetic aperture radar

    Microsoft Academic Search

    A. M. Horne; G. Yates

    2002-01-01

    Synthetic aperture radar (SAR) is becoming increasingly important in many military ground surveillance and targeting roles because of its ability to operate in all weather, day and night, and to detect, classify and geolocate objects at long stand-off ranges. Bistatic SAR, where the transmitter and receiver are on separate platforms, is seen as a potential means of countering vulnerability. This

  20. Rain radar instrument definition

    NASA Astrophysics Data System (ADS)

    Vincent, Nicolas; Chenebault, J.; Suinot, Noel; Mancini, Paolo L.

    1996-12-01

    As a result of a pre-phase a study, founded by ESA, this paper presents the definition of a spaceborne Rain Radar, candidate instrument for earth explorer precipitation mission. Based upon the description of user requirements for such a dedicated mission, a mission analysis defines the most suitable space segment. At system level, a parametric analysis compares pros and cons of instrument concepts associated with rain rate retrieval algorithms in order to select the most performing one. Several trade-off analysis at subsystem level leads then to the definition of the proposed design. In particular, as pulse compression is implemented in order to increase the radar sensitivity, the selected method to achieve a pulse response with a side-lobe level below--60 dB is presented. Antenna is another critical rain radar subsystem and several designs are com pared: direct radiating array, single or dual reflector illuminated by single or dual feed arrays. At least, feasibility of centralized amplification using TWTA is compared with criticality of Tx/Rx modules for distributed amplification. Mass and power budgets of the designed instrument are summarized as well as standard deviations and bias of simulated rain rate retrieval profiles. The feasibility of a compliant rain radar instrument is therefore demonstrated.

  1. Bistatic radar meteorological satellite

    NASA Technical Reports Server (NTRS)

    Nathanson, F. E.

    1981-01-01

    A technique is discussed that employs a radar transmitter with a moderate size antenna placed in a geosynchronous orbit with either a 0 degree or a low inclination orbit. The reflected signals from the precipitation are then received either on a single beam from a satellite having a beamwidth of about 6 degrees or preferably with a beam that scans the U.S. in a raster pattern with about 0.9 degrees beamwidth. While it would seem that a bistatic system with the transmitter at synchronous altitude and the receivers near the surface would not be a very efficient way of designing a radar system, it is somewhat surprising that the required power and antenna sizes are not that great. Two factors make the meteorological application somewhat more attractive than the bistatic detection of point targets. First, the bistatic reflections of radar signals from precipitation are to a large extent omnidirectional, and while raindrops are spheriods rather than spheres, the relationship of the reflectivity of the rain to rainfall rate can be easily derived. The second reason is that the rain echo signal level is independent of range from a receive only radar, and if the bistatic system works at all, it will work at long ranges.

  2. Weather and radar interactions

    Microsoft Academic Search

    J. P. Booth

    2005-01-01

    This paper discusses the effects of weather on radar system performance. This discussion were based on computer simulations and climatological data. The relationships between frequency and range were explored as they interact with the weather. This effort is being conducted in the RF Technology Division of the Applied Sensors, Guidance, and Electronics Directorate, US Army Aviation and Missile Research, Development,

  3. Distributed aperture OFDM radar

    Microsoft Academic Search

    Byung Wook Jung; R aviraj S. Adve; Joohwan Chun

    2009-01-01

    This paper presents a new method of obtaining frequency diversity using orthogonal frequency division multiplexing (OFDM). Exploiting spatial diversity, the key advantage of a distributed aperture radar, requires orthogonality in, for example, the frequency, time, waveform, dimensions across sensors. This paper focuses on the simplest of these cases; frequency orthogonality. Here we address the key drawback associated with frequency diversity:

  4. The determination of time-stationary two-dimensional convection patterns with single-station radars

    SciTech Connect

    Freeman, M.P.; Ruohoniemi, J.M.; Greenwald, R.A. (Johns Hopkins Univ., Laurel, MD (United States))

    1991-09-01

    At the present time, most ground-based radar estimations of ionospheric convection use observations from single-station facilities. This approach requires certain assumptions as to the spatial and/or temporal uniformity of the convection. In this paper the authors present a critical examination of the accuracy of these vector velocity determinations, using realistic modeled flow patterns that are time-stationary but not spatially uniform. They find that under certain circumstances the actual and inferred flow fields show considerable discrepancy, sometimes not even agreeing in the sense of flow direction. Specifically, they show that the natural curvature present in ionospheric convection on varying spatial scales can introduce significant error in the velocity estimate, particularly when the radius of curvature of the flow structure is less than or equal to the radar range to the scattering volume. The presence of flow curvature cannot be detected by radars which determine velocities from measurements in two viewing directions, and it might not be detected by radars using azimuth scanning techniques. Thus they argue that every effort should be made to measure the ionospheric convection by bidirectional or multidirectional observations of a common ionospheric volume and that a synthesis of coherent and incoherent radar observations from different sites is preferable to multidirectional single-station observations using either radar alone. These conclusions are applicable to any Doppler measurement technique and are equally valid for high-latitude wind patterns using Fabry-Perot interferometer techniques.

  5. Civilian vehicle radar data domes

    NASA Astrophysics Data System (ADS)

    Dungan, Kerry E.; Austin, Christian; Nehrbass, John; Potter, Lee C.

    2010-04-01

    We present a set of simulated X-band scattering data for civilian vehicles. For ten facet models of civilian vehicles, a high-frequency electromagnetic simulation produced fully polarized, far-field, monostatic scattering for 360 degrees azimuth and elevation angles from 30 to 60 degrees. The 369 GB of phase history data is stored in a MATLAB file format. This paper describes the CVDomes data set along with example imagery using 2D backprojection, single pass 3D, and multi-pass 3D.

  6. A heterodyne interferometer for angle metrology.

    PubMed

    Hahn, Inseob; Weilert, M; Wang, X; Goullioud, R

    2010-04-01

    We have developed a compact, high-resolution, angle measurement instrument based on a heterodyne interferometer. Common-path heterodyne interferometer metrology is used to measure displacements of a reflective target surface. In the interferometer set up, an optical mask is used to sample the laser beam reflecting back from four areas on a target surface. From the relative displacement measurements of the target surface areas, we can simultaneously determine angular rotations around two orthogonal axes in a plane perpendicular to the measurement beam propagation direction. The device is used in a testbed for a tracking telescope system where pitch and yaw angle measurements of a flat mirror are performed. Angle noise measurement of the device shows 0.1 nrad/square root of Hz at 1 Hz, at a working distance of 1 m. The operation range and nonlinearity of the device when used with a flat mirror is approximately +/-0.15 mrad, and 3 microrad rms, respectively. PMID:20441364

  7. Full-field Fabry-Perot interferometer

    SciTech Connect

    Mathews, A.R.; Boat, R.M.; Hemsing, W.F.; Warnes, R.H.; Whittemore, G.R.

    1991-01-01

    This paper describes the use of a Fabry-Perot interferometer for simultaneously measuring velocity at many points on the surface of a shock-loaded solid. The method is based upon work reported by S. Gidon and G. Behar in 1986, but the data analysis has been improved by the application of image-processing techniques. Light from a pulsed single-frequency laser is focused onto a moving target and the returned Doppler-shifted image passed through a Fabry-Perot interferometer. Output of the interferometer is a set of fringes that are formed for specific combinations of wavelength and light angle. These fringes are recorded on film for subsequent analysis. Fringe position determines the velocity for each point on the target that forms a fringe. A method for determining the velocity as a function of both position and time will also be discussed. 5 refs., 6 figs.

  8. Computing extinction maps of star nulling interferometers.

    PubMed

    Hénault, Francois

    2008-03-31

    Herein is discussed the performance of spaceborne nulling interferometers searching for extra-solar planets, in terms of their extinction maps projected on-sky. In particular, it is shown that the designs of Spatial Filtering (SF) and Achromatic Phase Shifter (APS) subsystems, both required to achieve planet detection and characterization, can sensibly affect the nulling maps produced by a simple Bracewell interferometer. Analytical relationships involving cross correlation products are provided and numerical simulations are performed, demonstrating marked differences in the aspect of extinction maps and the values of attained fringes contrasts. It is concluded that depending on their basic principles and designs, FS and APS will result in variable capacities for serendipitous discoveries of planets orbiting around their parent star. The mathematical relationships presented in this paper are assumed to be general, i.e. they should apply to other types of multi-apertures nulling interferometers. PMID:18542551

  9. [Design of a compact structure interferometer].

    PubMed

    Shi, Lei; Li, Kai; Gao, Zhi-Fan; Zeng, Li-Bo; Wu, Qiong-Shui

    2013-08-01

    A novel interferometer system based on the combinations of cube-corner reflectors and fixed plane mirrors was designed, the moving mirror drive system was designed and analysed, and its governor PID algorithm was used to ensure that the movement of the moving mirror is collimated, uniform and smooth. The parameters of the optical system of the interferometer and the optical devices were described. Finally, after validation of the experiment, it was indicated that the wave number accuracy, resolution, signal to noise ratio and other key indicators can meet the needs of practical application. PMID:24159897

  10. Low-noise interferometer for microwave radiometry

    NASA Technical Reports Server (NTRS)

    Timbie, P. T.; Wilkinson, D. T.

    1988-01-01

    An interferometer for precision measurements in microwave radiometry is proposed which uses two low-noise heterodyne receivers based on SIS tunnel junction mixers in the 40-50-GHz band. The antenna interference pattern has lobes which lead to positive output signals and lobes which give negative output, and the radiometer measures the difference in the power from these lobes without beam switching or instrument motion. The present system cancels instrumental signals, has a very low 1/f noise in the output, and has a zero outpus signal when viewing a uniform source. It is noted that application of the interferometer may be limited to radiometry with relatively large beams.

  11. Sensitivity of an imaging space infrared interferometer.

    PubMed

    Nakajima, T; Matsuhara, H

    2001-02-01

    We study the sensitivities of space infrared interferometers. We formulate the signal-to-noise ratios of infrared images obtained by aperture synthesis in the presence of source shot noise, background shot noise, and detector read noise. We consider the case in which n beams are combined pairwise at n(n-1)/2 detectors and the case in which all the n beams are combined at a single detector. We apply the results to future missions, Terrestrial Planet Finder and Darwin. We also discuss the potential of a far-infrared interferometer for a deep galaxy survey. PMID:18357026

  12. One-beam interferometer by beam folding.

    PubMed

    Ferrari, José A; Frins, Erna M

    2002-09-01

    A novel one-beam interferometer based on beam folding is described. The device resembles a Mach-Zehnder interferometer in which the two arms are located together in one collimated beam. Different halves of the same beam interfere with the help of a mirror--with its reflecting surface along the axis of the optical system--placed near the focal plane of the imaging lens. Phase-delay control is achieved by application of an electrical potential to a Pockels cell, which permits the use of techniques of phase-stepping interferometry. PMID:12211558

  13. Gravitational wave detectors based on matter wave interferometers (MIGO) are no better than laser interferometers (LIGO)

    E-print Network

    Albert Roura; Dieter R. Brill; B. L. Hu; Charles W. Misner; William D. Phillips

    2004-12-17

    We show that a recent claim that matter wave interferometers have a much higher sensitivity than laser interferometers for a comparable physical setup is unfounded. We point out where the mistake in the earlier analysis is made. We also disprove the claim that only a description based on the geodesic deviation equation can produce the correct physical result. The equations for the quantum dynamics of non-relativistic massive particles in a linearly perturbed spacetime derived here are useful for treating a wider class of related physical problems. A general discussion on the use of atom interferometers for the detection of gravitational waves is also provided.

  14. METR 4624--Radar Meteorology SPRING 2012

    E-print Network

    Droegemeier, Kelvin K.

    METR 4624--Radar Meteorology SPRING 2012 Dr. Michael I. Biggerstaff; drdoppler@ou.edu (best method Principles of weather radar and storm observations including: radar system design, em wave propagation, radar&Q, moments of the power spectrum, ground clutter, attenuation, rainfall measurements using radar reflectivity

  15. METR 4624--Radar Meteorology SPRING 2014

    E-print Network

    Droegemeier, Kelvin K.

    METR 4624--Radar Meteorology SPRING 2014 Dr. Michael I. Biggerstaff; drdoppler@ou.edu (best method Principles of weather radar and storm observations including: radar system design, em wave propagation, radar&Q, moments of the power spectrum, ground clutter, attenuation, rainfall measurements using radar reflectivity

  16. Modeling the imaging process in optical stellar interferometers

    Microsoft Academic Search

    M. Schöller; R. Wilhelm; B. Koehler

    2000-01-01

    Optical interferometers on the ground, like ESO's Very Large Telescope Interferometer (VLTI) and the Keck Interferometer, and in space, like the InfraRed Space Interferometer (IRSI\\/Darwin) and the Space Interferometry Mission (SIM), will bring a major breakthrough in optical and near-infrared high angular resolution astronomy at the beginning of the next millennium. These instruments are complex systems with an exceptionally interdisciplinary

  17. An MSK Radar Waveform

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Srinivasan, Meera

    2012-01-01

    The minimum-shift-keying (MSK) radar waveform is formed by periodically extending a waveform that separately modulates the in-phase and quadrature- phase components of the carrier with offset pulse-shaped pseudo noise (PN) sequences. To generate this waveform, a pair of periodic PN sequences is each passed through a pulse-shaping filter with a half sinusoid impulse response. These shaped PN waveforms are then offset by half a chip time and are separately modulated on the in-phase and quadrature phase components of an RF carrier. This new radar waveform allows an increase in radar resolution without the need for additional spectrum. In addition, it provides self-interference suppression and configurable peak sidelobes. Compared strictly on the basis of the expressions for delay resolution, main-lobe bandwidth, effective Doppler bandwidth, and peak ambiguity sidelobe, it appears that bi-phase coded (BPC) outperforms the new MSK waveform. However, a radar waveform must meet certain constraints imposed by the transmission and reception of the modulation, as well as criteria dictated by the observation. In particular, the phase discontinuity of the BPC waveform presents a significant impediment to the achievement of finer resolutions in radar measurements a limitation that is overcome by using the continuous phase MSK waveform. The phase continuity, and the lower fractional out-of-band power of MSK, increases the allowable bandwidth compared with BPC, resulting in a factor of two increase in the range resolution of the radar. The MSK waveform also has been demonstrated to have an ambiguity sidelobe structure very similar to BPC, where the sidelobe levels can be decreased by increasing the length of the m-sequence used in its generation. This ability to set the peak sidelobe level is advantageous as it allows the system to be configured to a variety of targets, including those with a larger dynamic range. Other conventionally used waveforms that possess an even greater spectral efficiency than the MSK waveform, such as linear frequency modulation (LFM) and Costas frequency hopping, have a fixed peak sidelobe level that is therefore not configurable, and can be exceeded by high contrast targets. Furthermore, in the case of a multistatic experiment observing a target in motion, self-interference from the transmitter to the receiver is mitigated by the MSK waveform. Waveforms that have delay Doppler coupling, such as LFM, provide no such protection.

  18. Noise analysis of a suspended high power Michelson interferometer

    Microsoft Academic Search

    Partha Saha

    1997-01-01

    The Laser Interferometer Gravitational Wave Observatory (LIGO Project) will search for gravitational waves by observing shifts in the interference of a Michelson interferometer. To start detecting gravitational waves with any measure of confidence, current estimates require the interferometer to be sensitive to differences of at least 10-9 radians in the phase of light. Ground- based LIGO will offer this sensitivity

  19. An electron Talbot-Lau interferometer and magnetic field sensing

    SciTech Connect

    Bach, Roger; Batelaan, Herman [Department of Physics and Astronomy, University of Nebraska-Lincoln, Theodore P. Jorgensen Hall, Lincoln, Nebraska 68588 (United States)] [Department of Physics and Astronomy, University of Nebraska-Lincoln, Theodore P. Jorgensen Hall, Lincoln, Nebraska 68588 (United States); Gronniger, Glen [The National Secure Manufacturing Center (NSMC), National Nuclear Security Administration's Kansas City Plant, National Security Campus, 14520 Botts Road, Kansas City, Missouri 64147 (United States)] [The National Secure Manufacturing Center (NSMC), National Nuclear Security Administration's Kansas City Plant, National Security Campus, 14520 Botts Road, Kansas City, Missouri 64147 (United States)

    2013-12-16

    We present a demonstration of a three grating Talbot-Lau interferometer for electrons. As a proof of principle, the interferometer is used to measure magnetic fields. The device is similar to the classical Moiré deflectometer. The possibility to extend this work to build a scaled-up electron deflectometer or interferometer for sensitive magnetic field sensing is discussed.

  20. Phase conjugate Twyman-Green interferometer for testing conicoidal surfaces

    NASA Technical Reports Server (NTRS)

    Shukla, R. P.; Dokhanian, Mostafa; Venkateswarlu, Putcha; George, M. C.

    1990-01-01

    An application of a phase conjugate Twyman-Green interferometer for testing a parabolic mirror is demonstrated. The interferometer is free from aberrations due to the self-focusing property of the phase conjugate mirror in one arm of the interferometer. It does not require a precision spherical mirror in the reference arm.

  1. An electron Talbot-Lau interferometer and magnetic field sensing

    NASA Astrophysics Data System (ADS)

    Bach, Roger; Gronniger, Glen; Batelaan, Herman

    2013-12-01

    We present a demonstration of a three grating Talbot-Lau interferometer for electrons. As a proof of principle, the interferometer is used to measure magnetic fields. The device is similar to the classical Moiré deflectometer. The possibility to extend this work to build a scaled-up electron deflectometer or interferometer for sensitive magnetic field sensing is discussed.

  2. Radar images of Mars

    NASA Technical Reports Server (NTRS)

    Muhleman, Duane O.; Butler, Bryan J.; Grossman, Arie W.; Slade, Martin A.

    1991-01-01

    VLA radar-reflected flux-density mappings have yielded full disk images of Mars which reveal near-surface features, including a region in the Tharsis volcano area that displayed no echo to the very low level of the radar-system noise. This feature is interpreted as a deposit of dust or ash whose density is less than about 0.5 g/cu cm; it must be several meters thick, and may be much deeper. The most strongly reflecting geological feature was the south polar ice cap, which is interpretable as arising from nearly-pure CO2 or H2O ice, with less than 2 vol pct Martian dust. Only one anomalous reflecting feature was identified outside the Tharsis region.

  3. New weather radar coming

    NASA Astrophysics Data System (ADS)

    Maggs, William Ward

    What would you call the next generation of radar for severe weather prediction? NEXRAD, of course. A prototype for the new system was recently completed in Norman, Okla., and by the early 1990s up to 195 stations around the United States will be tracking dangerous weather and sending faster, more accurate, and more detailed warnings to the public.NEXRAD is being built for the Departments of Commerce, Transportation, and Defense by the Unisys Corporation under a $450 million contract signed in December 1987. Th e system will be used by the National Weather Service, the Federal Aviation Administration (FAA), and the U.S. Air Force and Navy. The NEXRAD radar tower in Norman is expected to be operational in October.

  4. Control of Formation-Flying Multi-Element Space Interferometers with Direct Interferometer-Output Feedback

    NASA Technical Reports Server (NTRS)

    Lu, Hui-Ling; Cheng, Victor H. L.; Lyon, Richard G.; Carpenter, Kenneth G.

    2007-01-01

    The long-baseline space interferometer concept involving formation flying of multiple spacecrafts holds great promise as future space missions for high-resolution imagery. A major challenge of obtaining high-quality interferometric synthesized images from long-baseline space interferometers is to accurately control these spacecraft and their optics payloads in the specified configuration. Our research focuses on the determination of the optical errors to achieve fine control of long-baseline space interferometers without resorting to additional sensing equipment. We present a suite of estimation tools that can effectively extract from the raw interferometric image relative x/y, piston translational and tip/tilt deviations at the exit pupil aperture. The use of these error estimates in achieving control of the interferometer elements is demonstrated using simulated as well as laboratory-collected interferometric stellar images.

  5. Cognitive processing for nonlinear radar

    NASA Astrophysics Data System (ADS)

    Martone, Anthony; Ranney, Kenneth; Hedden, Abigail; Mazzaro, Gregory; McNamara, David

    2013-05-01

    An increasingly cluttered electromagnetic environment (EME) is a growing problem for radar systems. This problem is becoming critical as the available frequency spectrum shrinks due to growing wireless communication device usage and changing regulations. A possible solution to these problems is cognitive radar, where the cognitive radar learns from the environment and intelligently modifies the transmit waveform. In this paper, a cognitive nonlinear radar processing framework is introduced where the main components of this framework consist of spectrum sensing processing, target detection and classification, and decision making. The emphasis of this paper is to introduce a spectrum sensing processing technique that identifies a transmit-receive frequency pair for nonlinear radar. It will be shown that the proposed technique successfully identifies a transmit-receive frequency pair for nonlinear radar from data collected from the EME.

  6. A review of array radars

    NASA Astrophysics Data System (ADS)

    Brookner, E.

    1981-10-01

    Achievements in the area of array radars are illustrated by such activities as the operational deployment of the large high-power, high-range-resolution Cobra Dane; the operational deployment of two all-solid-state high-power, large UHF Pave Paws radars; and the development of the SAM multifunction Patriot radar. This paper reviews the following topics: array radars steered in azimuth and elevation by phase shifting (phase-phase steered arrays); arrays steered + or - 60 deg, limited scan arrays, hemispherical coverage, and omnidirectional coverage arrays; array radars steering electronically in only one dimension, either by frequency or by phase steering; and array radar antennas which use no electronic scanning but instead use array antennas for achieving low antenna sidelobes.

  7. Outline of the Mu radar

    NASA Technical Reports Server (NTRS)

    Kato, S.

    1983-01-01

    A middle and upper atmospheric radar system is described. The antenna array consists of 25 groups each of which consists of 19 crossed-Yagis with three elements; each antenna has semiconductor transmitter and receiver, called a module, and each group of 19 antennas works as an independent small radar steering its radar beam under the control of a microcomputer. Thus, the total system consists of 25 small radars of this kind, enabling one to do various sophisticated operations with the system. The system is controlled by two other computers, one for radar controlling (HP9835A) and the other for data taking and on-line analysis (VAX11/750). The computer-controlled system is simple in operation for users and reliable in observation. Very quick beam steering (as quick as in a msec) is also possible because of electronic phase-changing of each module output under control of the microcomputer which is further controlled by the radar controller.

  8. Airborne bistatic radar applications

    Microsoft Academic Search

    James A. Foster

    1987-01-01

    Applications of bistatic radar when one or both of the units are airborne are discussed. Scenarios that merit deeper consideration are covert strike and head-on SAR using a stand-off illuminator, either airborne or space-based; area air defense with passive ground-based receivers and stand-off illuminators; an airborne picket line to detect stealth aircraft and missiles; AWACS aircraft providing mutual support in

  9. Radar receiver procedures

    NASA Astrophysics Data System (ADS)

    1990-04-01

    This International Test Operations Procedures (ITOP) outlines the test methods used in evaluating the performance and characteristics of general types of radar receivers to include single or variable frequency receivers. The test methods serve as a guide in determining the overall efficiency of such equipment as a function of their design and their recorded performance. If a conflict exists between the accuracies, frequency, and levels stated in this ITOP and those stated in the appropriate requirements documents, the requirements documents must be used.

  10. Imaging synthetic aperture radar

    DOEpatents

    Burns, Bryan L. (Tijeras, NM); Cordaro, J. Thomas (Albuquerque, NM)

    1997-01-01

    A linear-FM SAR imaging radar method and apparatus to produce a real-time image by first arranging the returned signals into a plurality of subaperture arrays, the columns of each subaperture array having samples of dechirped baseband pulses, and further including a processing of each subaperture array to obtain coarse-resolution in azimuth, then fine-resolution in range, and lastly, to combine the processed subapertures to obtain the final fine-resolution in azimuth. Greater efficiency is achieved because both the transmitted signal and a local oscillator signal mixed with the returned signal can be varied on a pulse-to-pulse basis as a function of radar motion. Moreover, a novel circuit can adjust the sampling location and the A/D sample rate of the combined dechirped baseband signal which greatly reduces processing time and hardware. The processing steps include implementing a window function, stabilizing either a central reference point and/or all other points of a subaperture with respect to doppler frequency and/or range as a function of radar motion, sorting and compressing the signals using a standard fourier transforms. The stabilization of each processing part is accomplished with vector multiplication using waveforms generated as a function of radar motion wherein these waveforms may be synthesized in integrated circuits. Stabilization of range migration as a function of doppler frequency by simple vector multiplication is a particularly useful feature of the invention; as is stabilization of azimuth migration by correcting for spatially varying phase errors prior to the application of an autofocus process.

  11. Shuttle imaging radar experiment

    USGS Publications Warehouse

    Elachi, C.; Brown, W.E.; Cimino, J.B.; Dixon, T.; Evans, D.L.; Ford, J.P.; Saunders, R.S.; Breed, C.; Masursky, H.; McCauley, J.F.; Schaber, G.; Dellwig, L.; England, A.; MacDonald, H.; Martin-Kaye, P.; Sabins, F.

    1982-01-01

    The shuttle imaging radar (SIR-A) acquired images of a variety of the earth's geologic areas covering about 10 million square kilometers. Structural and geomorphic features such as faults, folds, outcrops, and dunes are clearly visible in both tropical and arid regions. The combination of SIR-A and Seasat images provides additional information about the surface physical properties: topography and roughness. Ocean features were also observed, including large internal waves in the Andaman Sea. Copyright ?? 1982 AAAS.

  12. Adaptive elements in a precision laser interferometer

    NASA Astrophysics Data System (ADS)

    Simonova, Galina V.; Polovtsev, Igor G.; Tartakovsky, Valery A.

    2004-02-01

    The accuracy of a high-precision interferometric experiment depends on both instrument errors and errors connected with processing the interferograms. Both types of errors can be minimized by an optimum adjustment of the functions of the basic unit of the system. The paper addresses the issue of error optimization using different adaptive systems within a laser interferometer design.

  13. Spatial phase-shifting lateral shearing interferometer

    NASA Astrophysics Data System (ADS)

    Guo, Xiaoxian; Zeng, Aijun; Huang, Huijie

    2008-12-01

    The phase-shifting lateral shearing interferometer is widely adopted for wavefront measurement with high accuracy. For real-time wavefront measurement, a spatial phase-shifting lateral shearing interferometer is proposed. The interferometer includes a polarization lateral shearing module, a spatial phase-shifting module and an imaging module. The polarization lateral shearing module consists of a Savart polariscope. The spatial phase-shifting module is component of a non-polarization beam splitter, a polarization beam splitter, two rectangular prisms and a half wave-plate. The imaging module includes an imaging system and a CCD. The measured wavefront is sheared by the polarization lateral shearing module. The polarization directions of the two shearing beams are perpendicular to each other. The two shearing beams are split into four groups of beams by the spatial phase-shifting module to form four interferograms in a 2x2 matrix. The phase step of the four interferograms is 90 degrees. The four interferograms are captured in a single frame image by the imaging module. In experiments, a spherical wavefront with large radius of curvature was measured. Four spatial phase-shifting interferograms of the wavefront was obtained simultaneously. The usefulness of the interferometer is verified.

  14. A Novel Vector Microwave Phase Interferometer

    Microsoft Academic Search

    Jan Zela; Karel Hoffmannn; Premysl Hudec

    2006-01-01

    The paper describes a concept of a novel vector microwave phase interferometer based on a vector network analyzer system. The instrument is designed for fast vector measurements of a space distribution of an interference electromagnetic field using a matrix of antennas. It is supposed to be used in non-contact deformation and non-homogeneity measurements in civil engineering and other areas. Results

  15. Control system of the VLT Interferometer

    Microsoft Academic Search

    Massimo Verola

    1998-01-01

    During an interferometric observation the successful coordination of all the complex and heterogeneous devices of the VLT interferometer (VLTI) depends on the effectiveness and reliability of the control system, which carries out the ultimate system integration. The VLTI control system (VLTICS) is designed to satisfy both specific technical requirements and general operational constraints. It profits by the valuable experience gained

  16. Microwave interferometer techniques for detonation study

    Microsoft Academic Search

    P. L. Stanton; E. L. Venturini; R. W. Dietzel

    1985-01-01

    Techniques have been developed to improve resolution in microwave interferometry of detonating explosives. Unwanted reflections in the measurement arm of the interferometer result in phase distortion of the recorded signal. By using tuning techniques, unwanted reflections can be virtually eliminated, and phase distortion is minimized, for some experimental conditions. The use of a quadrature detector and an intensity monitor also

  17. Multipass holographic interferometer improves image resolution

    NASA Technical Reports Server (NTRS)

    Brooks, R. E.; Heflinger, L. O.

    1970-01-01

    Multipass holographic interferometer forms a hologram of high diffraction efficiency, and hence provides a bright and high contrast interferogram. It is used to study any effect which changes the index of refraction and to study surface deformations of a flat reflecting surface.

  18. Analysis of a Twophoton Interferometer Frank Rioux

    E-print Network

    Rioux, Frank

    , an atom simultaneously emits identical photons to the east and west. Two paths (long and short) are available to detectors A and B in the east and west arms of the interferometer. The short paths are the same on both sides, but the long paths can have different lengths causing phase differences for the east

  19. The VIRGO interferometer for gravitational wave detection

    Microsoft Academic Search

    V. Ferrari; E. Majorana; P. Puppo; P. Rapagnani; F. Ricci; F. Marion; L. Massonnet; C. Mehmel; R. Morand; B. Mours; V. Sannibale; M. Yvert; D. Babusci; S. Bellucci; S. Candusso; G. Giordano; G. Matone; J.-M. Mackowski; L. Pinard; F. Barone; E. Calloni; L. di Fiore; M. Flagiello; F. Garuti; A. Grado; M. Longo; M. Lops; S. Marano; L. Milano; S. Solimeno; V. Brisson; F. Cavalier; M. Davier; P. Hello; P. Heusse; P. Mann; Y. Acker; M. Barsuglia; B. Bhawal; F. Bondu; A. Brillet; H. Heitmann; J.-M. Innocent; L. Latrach; C. N. Man; M. Pham-Tu; E. Tournier; M. Taubmann; J.-Y. Vinet; C. Boccara; Ph. Gleyzes; V. Loriette; J.-P. Roger; G. Cagnoli; L. Gammaitoni; J. Kovalik; F. Marchesoni; M. Punturo; M. Beccaria; M. Bernardini; E. Bougleux; S. Braccini; C. Bradaschia; G. Cella; A. Ciampa; E. Cuoco; G. Curci; R. del Fabbro; R. de Salvo; A. di Virgilio; D. Enard; I. Ferrante; F. Fidecaro; A. Giassi; A. Giazotto; L. Holloway; P. La Penna; G. Losurdo; S. Mancini; M. Mazzoni; F. Palla; H.-B. Pan; D. Passuello; P. Pelfer; R. Poggiani; R. Stanga; A. Vicere; Z. Zhang

    1997-01-01

    The Virgo gravitational wave detector is an interferometer with 3 km long arms in construction near Pisa in Italy. The accessible sources at the design sensitivity and main noises are reviewed. Virgo has devoted a significant effort to extend sensitivity to low frequency reaching the strain level h~ = 10-21 Hz-1\\/2 at 10 Hz while at 200 Hzh~ = 3

  20. A stellar interferometer on the Moon

    Microsoft Academic Search

    Irene Porro

    1997-01-01

    The work I present in this document has been divided into two main parts, the first one related to the IOTA project and the second one related to the study on the lunar interferometer, and an introduction section. Each section can be read independently from the other, however they are presented following the logical order in which the research work

  1. Overview of the Palomar Testbed Interferometer

    NASA Astrophysics Data System (ADS)

    Colavita, M. M.

    1999-12-01

    The Palomar Testbed Interferometer (PTI) is a long baseline near-IR interferometer developed by JPL for NASA and installed at Palomar Observatory; first fringes were obtained in 1995. PTI serves as a testbed for other interferometer projects, especially the Keck Interferometer. PTI is capable of high accuracy fringe amplitude measurements at H and K using active fringe tracking over its 110-m baseline. Good visibilities are routinely obtained on sources as faint as 5.5 mK, with visibility calibration accuracies of 1.5-2% on brighter sources. The instrument is highly automated, and up to 100 130-sec scans per night are possible, allowing efficient pursuit of "amplitude" science on single and binary stars, and driving the development of automated planning, analysis, and archiving tools. PTI also incorporates a dual-star capability to enable high accuracy narrow-angle differential astrometry. From measurements of a bright visual binary, short-term precisions which correspond to a noise floor of less than 50 uas in an hour have been achieved, along with night-to-night positional repeatability of 100 uas over a 7-night run.

  2. Radar gun hazards

    SciTech Connect

    Not Available

    1991-12-20

    Radar guns - hand-held units used by the law to nail speeders - have been in use since the early '60s. Now they've been accused of causing cancer. Police officers in several states have so far filed eight suits against the manufacturer, claiming that they have contracted rare forms of cancer, such as of the eyelid and the testicle, from frequent proximity to the devices. Spurred by concerns expressed by police groups, researchers at the Rochester Institute of Technology are conducting what they believe to be the first research of its kind in the nation. Last month psychologist John Violanti, an expert in policy psychology and health, sent out a one-page survey to 6,000 active and retired police officers in New York State, asking them about their health and their use of radar guns. Violanti says melanoma, leukemia, and lymph node cancer may be linked to these as well as other electromagnetic devices. The Food and Drug Administration earlier this year issued a warning about radar guns, telling users not to operate them closer than 6 inches from the body. But this may not be a sufficient safeguard since the instruments can give off crisscrossing wave emissions within a police vehicle. The survey will be used to help determine if it would be safer to mount the guns, which are currently either hand-held or mounted on dashboards, outside troopers' cars.

  3. Comet radar explorer

    NASA Astrophysics Data System (ADS)

    Farnham, Tony; Asphaug, Erik; Barucci, Antonella; Belton, Mike; Bockelee-Morvan, Dominique; Brownlee, Donald; Capria, Maria Teresa; Carter, Lynn; Chesley, Steve; Farnham, Tony; Gaskell, Robert; Gim, Young; Heggy, Essam; Herique, Alain; Klaasen, Ken; Kofman, Wlodek; Kreslavsky, Misha; Lisse, Casey; Orosei, Roberto; Plaut, Jeff; Scheeres, Dan

    The Comet Radar Explorer (CORE) is designed to perform a comprehensive and detailed exploration of the interior, surface, and inner coma structures of a scientifically impor-tant Jupiter family comet. These structures will be used to investigate the origins of cometary nuclei, their physical and geological evolution, and the mechanisms driving their spectacular activity. CORE is a high heritage spacecraft, injected by solar electric propulsion into orbit around a comet. It is capable of coherent deep radar imaging at decameter wavelengths, high resolution stereo color imaging, and near-IR imaging spectroscopy. Its primary objective is to obtain a high-resolution map of the interior structure of a comet nucleus at a resolution of ¿100 elements across the diameter. This structure shall be related to the surface geology and morphology, and to the structural details of the coma proximal to the nucleus. This is an ideal complement to the science from recent comet missions, providing insight into how comets work. Knowing the structure of the interior of a comet-what's inside-and how cometary activity works, is required before we can understand the requirements for a cryogenic sample return mission. But more than that, CORE is fundamental to understanding the origin of comets and their evolution in time. The mission is made feasible at low cost by the use of now-standard MARSIS-SHARAD reflec-tion radar imaging hardware and data processing, together with proven flight heritage of solar electric propulsion. Radar flight heritage has been demonstrated by the MARSIS radar on Mars Express (Picardi et al., Science 2005; Plaut et al., Science 2007), the SHARAD radar onboard the Mars Reconnaissance Orbiter (Seu et al., JGR 2007), and the LRS radar onboard Kaguya (Ono et al, EPS 2007). These instruments have discovered detailed subsurface structure to depths of several kilometers in a variety of terrains on Mars and the Moon. A reflection radar deployed in orbit about a comet will enjoy significant simplifying benefits compared to using the same instrument for Mars or lunar radar science: (1) The proximity of operations leads to a much higher signal to noise, as much as +30 dB. (2) The lack of an ionosphere simplifies data modeling and analysis. (3) The body is globally illuminated during every data acquisition, minimizing ambiguity or 'clutter' and allowing for tomographic reconstruction. What is novel is the data processing, where instead of a planar radargram approach we coherently process the data into an image of the deep interior. CORE thus uses a MARSIS-SHARAD heritage radar to make coherent reflection sounding measurements, a 'CAT SCAN' of a comet nucleus. What is unique about this mission compared to the Mars radars mentioned above, is that the target is a finite mass of dirty ice in free space, rather than a sheet of dirty ice draped on a planet surface. The depth of penetration (kilometers), attainable resolution (decameters), and the target materials, are more or less the same. This means that the science story is robust, and the radar implementation is robust. The target is comet 10P/Tempel 2, discovered by Wilhelm Tempel in 1873 and observed on most apparitions since. It has been extensively studied, in part because of interest as a CRAF target in the mid-1980s, and much is known about it. Tempel 2 is one of the largest known comet nuclei, 16×8×8 km (about the same size as Halley) [1] and has rotation period 8.9 hours [3,5,6,7,9]. The spin state is evolving with time, spinning up by ˜10 sec per perihelion pass [5,7]. The comet is active, but not exceedingly so, especially given its size. The water production is measured at ˜ 4 × 1028 mol/sec at its peak [2], a factor of 25 lower than comet Halley, and it is active over only ˜2% of its surface. The dust environment is well known, producing a factor of ˜100 less dust than Halley. Comet References: [1] A'Hearn et al., ApJ 347, 1155, 1989 [2] Feldman and Festou, ACM 1991, p. 171, 1992 [3] Jewitt and Luu, AJ 97, 1766, 1989 [4] Lamy et al., Comets II p 223. 2009 [5] Muel

  4. Spaceborne Imaging Radar Project

    NASA Technical Reports Server (NTRS)

    Herman, Neil

    1986-01-01

    In June of 1985 the Project Initiation Agreement was signed by the Jet Propulsion Laboratory and the NASA Office of Space Science and Applications for the Spaceborne Imaging Radar Project (SIR). The thrust of the Spaceborne Imaging Radar Project is to continue the evolution of synthetic aperture radar (SAR) science and technology developed during SEASAT, SIR-A and SIR-B missions to meet the needs of the Earth Observing System (EOS) in the mid 1990's. As originally formulated, the Project plans were for a reflight of the SIR-B in 1987, the development of a new SAR, SIR-C, for missions in mid 1989 and early 1990, and the upgrade of SIR-C to EOS configuration with a qualification flight aboard the shuttle in the 1993 time frame (SIR-D). However, the loss of the shuttle Challenger has delayed the first manifest for SIR to early 1990. This delay prompted the decision to drop SIR-B reflight plans and move ahead with SIR-C to more effectively utilize this first mission opportunity. The planning for this project is discussed.

  5. The Shuttle Radar Topography Mission

    NASA Astrophysics Data System (ADS)

    Farr, Tom G.; Rosen, Paul A.; Caro, Edward; Crippen, Robert; Duren, Riley; Hensley, Scott; Kobrick, Michael; Paller, Mimi; Rodriguez, Ernesto; Roth, Ladislav; Seal, David; Shaffer, Scott; Shimada, Joanne; Umland, Jeffrey; Werner, Marian; Oskin, Michael; Burbank, Douglas; Alsdorf, Douglas

    2007-06-01

    The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth. The project was a joint endeavor of NASA, the National Geospatial-Intelligence Agency, and the German and Italian Space Agencies and flew in February 2000. It used dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution. Details of the development, flight operations, data processing, and products are provided for users of this revolutionary data set.

  6. Space-based radar handbook

    Microsoft Academic Search

    Leopold J. Cantafio

    1989-01-01

    The design and operation of space-based radar (SBR) systems are discussed in chapters contributed by leading experts. An overview of current and planned SBRs is presented, and particular attention is given to SBR-platform orbits, the ionospheric environment and its effects on SBR detection, space-based SARs, bistatic SBRs, rendezvous radars, radar altimeters for space vehicles, scatterometers and other modest-resolution systems, and

  7. Radar-aeolian roughness project

    NASA Technical Reports Server (NTRS)

    Greeley, Ronald; Dobrovolskis, A.; Gaddis, L.; Iversen, J. D.; Lancaster, N.; Leach, Rodman N.; Rasnussen, K.; Saunders, S.; Vanzyl, J.; Wall, S.

    1991-01-01

    The objective is to establish an empirical relationship between measurements of radar, aeolian, and surface roughness on a variety of natural surfaces and to understand the underlying physical causes. This relationship will form the basis for developing a predictive equation to derive aeolian roughness from radar backscatter. Results are given from investigations carried out in 1989 on the principal elements of the project, with separate sections on field studies, radar data analysis, laboratory simulations, and development of theory for planetary applications.

  8. Overview of Radar Data Compression Valliappa Lakshmanan

    E-print Network

    Lakshmanan, Valliappa

    Overview of Radar Data Compression Valliappa Lakshmanan Cooperative Institute of Mesoscale Meteorological Studies University of Oklahoma & National Severe Storms Laboratory Abstract Radar data is routinely transmitted in real-time from the coterminous United States (CONUS) radar sites and placed

  9. REVIEW ARTICLE Interferometric Synthetic Aperture Radar

    E-print Network

    Kansas, University of

    REVIEW ARTICLE Interferometric Synthetic Aperture Radar Christopher T. Allen Department of Electrical Engineering and Computer Science and Radar Systems and Remote Sensing Laboratory University of Kansas Abstract. This paper provides a brief review of interferometric synthetic aperture radar (In

  10. Solid-state radar transmitters

    NASA Astrophysics Data System (ADS)

    Ostroff, E. D.; Borkowski, M.; Thomas, H.; Curtis, J.

    The technology and design procedures for introducing transistors into radio transmitters are discussed. The design characteristics of solid-state radar transmitters are described, with emphasis given to power amplifier/modules and devices for summing the output power in space or in an output combiner. Some design issues related to power supplies, pulse waveform amplitude regulation; reliability; and cost; and also considered. Some examples of successful solid-state radar systems are described, including the AN/TPS-59 radar, the AN/SPS-40 system, and the Pave/PAWS phased array radar. Black and white photographs of the different systems are provided.

  11. Radar data processing and analysis

    NASA Technical Reports Server (NTRS)

    Ausherman, D.; Larson, R.; Liskow, C.

    1976-01-01

    Digitized four-channel radar images corresponding to particular areas from the Phoenix and Huntington test sites were generated in conjunction with prior experiments performed to collect X- and L-band synthetic aperture radar imagery of these two areas. The methods for generating this imagery are documented. A secondary objective was the investigation of digital processing techniques for extraction of information from the multiband radar image data. Following the digitization, the remaining resources permitted a preliminary machine analysis to be performed on portions of the radar image data. The results, although necessarily limited, are reported.

  12. Radar Image, Hokkaido, Japan

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The southeast part of the island of Hokkaido, Japan, is an area dominated by volcanoes and volcanic caldera. The active Usu Volcano is at the lower right edge of the circular Lake Toya-Ko and near the center of the image. The prominent cone above and to the left of the lake is Yotei Volcano with its summit crater. The city of Sapporo lies at the base of the mountains at the top of the image and the town of Yoichi -- the hometown of SRTM astronaut Mamoru Mohri -- is at the upper left edge. The bay of Uchiura-Wan takes up the lower center of the image. In this image, color represents elevation, from blue at the lowest elevations to white at the highest. The radar image has been overlaid to provide more details of the terrain. Due to a processing problem, an island in the center of this crater lake is missing and will be properly placed when further SRTM swaths are processed. The horizontal banding in this image is a processing artifact that will be removed when the navigation information collected by SRTM is fully calibrated. This image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. Size: 100 by 150 kilometers (62 by 93 miles) Location: 42.5 deg. North lat., 140.3 deg. East lon. Orientation: North towards upper left Image Data: SRTM Original Data Resolution: SRTM 30 meters (99 feet) Date Acquired: February 17, 2000

  13. Compact in-line laser radial shear interferometer

    NASA Technical Reports Server (NTRS)

    Shukla, R. P.; Moghbel, M.; Venkateswarlu, P.

    1992-01-01

    A compact in-line radial shearing interferometer using laser as a light source is presented. The interferometer is made out of a cube-type beam splitter so that the two opposite surfaces are generated with different curvatures while the normal to the entrance and exit surfaces are in the same line. The interferometer is simple to make and easy to align. Aberration analysis of the interferometer is also presented. Some applications of the interferometer for testing lenses and infrared optical systems and for accessing the quality of an emerging wave front from the exit slit of a monochromator are suggested.

  14. A generalized, periodic nonlinearity-reduced interferometer for straightness measurements

    SciTech Connect

    Wu Chienming [Department of Biomedical Engineering and Environmental Sciences, National TsingHua University, Hsinchu 300, Taiwan (China)

    2008-06-15

    Periodic nonlinearity is a systematic error limiting the accuracy of displacement measurements at the nanometer level. However, an interferometer with a displacement measurement accuracy of less than 1 nm is required in nanometrology and in fundamental scientific research. To meet this requirement, a generalized, periodic nonlinearity-reduced interferometer, based on three construction principles has been developed for straightness measurements. These three construction principles have resulted in an interferometer with a highly stable design with reduced periodic nonlinearity. Verifications by a straightness interferometer have demonstrated that the periodic nonlinearity was less than 40 pm. The results also demonstrate that the interferometer design is capable of subnanometer accuracy and is useful in nanometrology.

  15. Millimeter Wave Cloud Radar (MMCR) Handbook

    SciTech Connect

    KB Widener; K Johnson

    2005-01-30

    The millimeter cloud radar (MMCR) systems probe the extent and composition of clouds at millimeter wavelengths. The MMCR is a zenith-pointing radar that operates at a frequency of 35 GHz. The main purpose of this radar is to determine cloud boundaries (e.g., cloud bottoms and tops). This radar will also report radar reflectivity (dBZ) of the atmosphere up to 20 km. The radar possesses a doppler capability that will allow the measurement of cloud constituent vertical velocities.

  16. Investigation of Space Interferometer Control Using Imaging Sensor Output Feedback

    NASA Technical Reports Server (NTRS)

    Leitner, Jesse A.; Cheng, Victor H. L.

    2003-01-01

    Numerous space interferometry missions are planned for the next decade to verify different enabling technologies towards very-long-baseline interferometry to achieve high-resolution imaging and high-precision measurements. These objectives will require coordinated formations of spacecraft separately carrying optical elements comprising the interferometer. High-precision sensing and control of the spacecraft and the interferometer-component payloads are necessary to deliver sub-wavelength accuracy to achieve the scientific objectives. For these missions, the primary scientific product of interferometer measurements may be the only source of data available at the precision required to maintain the spacecraft and interferometer-component formation. A concept is studied for detecting the interferometer's optical configuration errors based on information extracted from the interferometer sensor output. It enables precision control of the optical components, and, in cases of space interferometers requiring formation flight of spacecraft that comprise the elements of a distributed instrument, it enables the control of the formation-flying vehicles because independent navigation or ranging sensors cannot deliver the high-precision metrology over the entire required geometry. Since the concept can act on the quality of the interferometer output directly, it can detect errors outside the capability of traditional metrology instruments, and provide the means needed to augment the traditional instrumentation to enable enhanced performance. Specific analyses performed in this study include the application of signal-processing and image-processing techniques to solve the problems of interferometer aperture baseline control, interferometer pointing, and orientation of multiple interferometer aperture pairs.

  17. Investigation of Space Interferometer Control Using Imaging Sensor Output Feedback

    NASA Technical Reports Server (NTRS)

    Cheng, Victore H. L.; Leitner, Jesse A.

    2003-01-01

    Numerous space interferometry missions are planned for the next decade to verify different enabling technologies towards very-long-baseline interferometry to achieve high-resolution imaging and high-precision measurements. These objectives will require coordinated formations of spacecraft separately carrying optical elements comprising the interferometer. High-precision sensing and control of the spacecraft and the interferometer-component payloads are necessary to deliver sub-wavelength accuracy to achieve the scientific objectives. For these missions, the primary scientific product of interferometer measurements may be the only source of data available at the precision required to maintain the spacecraft and interferometer-component formation. A concept is studied for detecting the interferometer's optical configuration errors based on information extracted from the interferometer sensor output. It enables precision control of the optical components, and, in cases of space interferometers requiring formation flight of spacecraft that comprise the elements of a distributed instrument, it enables the control of the formation flying vehicles because independent navigation or ranging sensors cannot deliver the high-precision metrology over the entire required geometry. Since the concept can act on the quality of the interferometer output directly, it can detect errors outside the capability of traditional metrology instruments, and provide the means needed to augment the traditional instrumentation to enable enhanced performance. Specific analyses performed in this study include the application of signal-processing and image-processing techniques to solve the problems of interferometer aperture baseline control, interferometer pointing, and orientation of multiple interferometer aperture pairs.

  18. Removing interfering clutter associated with radar pulses that an airborne radar receives from a radar transponder

    DOEpatents

    Ormesher, Richard C. (Albuquerque, NM); Axline, Robert M. (Albuquerque, NM)

    2008-12-02

    Interfering clutter in radar pulses received by an airborne radar system from a radar transponder can be suppressed by developing a representation of the incoming echo-voltage time-series that permits the clutter associated with predetermined parts of the time-series to be estimated. These estimates can be used to estimate and suppress the clutter associated with other parts of the time-series.

  19. Laser-Ranging Long Baseline Differential Atom Interferometers for Space

    E-print Network

    Chiow, Sheng-wey; Yu, Nan

    2015-01-01

    High sensitivity differential atom interferometers are promising for precision measurements in science frontiers in space, including gravity field mapping for Earth science studies and gravitational wave detection. We propose a new configuration of twin atom interferometers connected by a laser ranging interferometer (LRI-AI) to provide precise information of the displacements between the two AI reference mirrors and a means to phase-lock the two independent interferometer lasers over long distances, thereby further enhancing the feasibility of long baseline differential atom interferometers. We show that a properly implemented LRI-AI can achieve equivalent functionality to the conventional differential atom interferometer measurement system. LRI-AI isolates the laser requirements for atom interferometers and for optical phase readout between distant locations, thus enabling optimized allocation of available laser power within a limited physical size and resource budget. A unique aspect of LRI-AI also enables...

  20. Planetary radar studies. [radar mapping of the Moon and radar signatures of lunar and Venus craters

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.; Cutts, J. A.

    1981-01-01

    Progress made in studying the evolution of Venusian craters and the evolution of infrared and radar signatures of lunar crater interiors is reported. Comparison of radar images of craters on Venus and the Moon present evidence for a steady state Venus crater population. Successful observations at the Arecibo Observatory yielded good data on five nights when data for a mix of inner and limb areas were acquired. Lunar craters with radar bright ejects are discussed. An overview of infrared radar crater catalogs in the data base is included.

  1. Imaging Radar for Ecosystem Studies

    NASA Technical Reports Server (NTRS)

    Waring, Richard H.; Way, JoBea; Hunt, E. Raymond J.; Morrissey, Leslie; Ranson, K. Jon; Weishampel, John F.; Oren, Ram; Franklin, Steven E.

    1996-01-01

    Recently a number of satellites have been launched with radar sensors, thus expanding opportunities for global assessment. In this article we focus on the applications of imaging radar, which is a type of sensor that actively generates pulses of microwaves and, in the interval between sending pulses, records the returning signals reflected back to an antenna.

  2. Rendezvous radar for orbital vehicles

    Microsoft Academic Search

    John W. Locke; Larry D. Casey

    1992-01-01

    In this paper some of the factors which relate to the system design of rendezvous radars are discussed and the system design and the capabilities of the OMV Rendezvous Radar System (RRS) are described. The potential for transferring manufacturing technologies and methods which have been developed for high-volume-production commercial and military hardware systems into the relatively low volume world of

  3. OFDM waveforms for multistatic radars

    Microsoft Academic Search

    Y. Paichard

    2010-01-01

    In this paper, the benefits of OFDM waveforms are analyzed for multistatic radar systems, where several radar stations cooperate in the same frequency band. The signal is coded over a 2D pattern, in the time and the frequency domains, using orthogonal Golay complementary sets derived from Reed-Muller codes. Binary data are also encoded in the signal. The obtained ambiguity and

  4. Frequency diversity in multistatic radars

    Microsoft Academic Search

    Byung Wook Jung; R aviraj S. Adve; Joohwan Chun

    2008-01-01

    This paper presents the model and analysis of a frequency-diverse radar system. Multistatic radar systems provide an inherent spatial diversity by processing signals from different platforms which view a potential target from different aspect angles. By using different frequencies at each platform, an additional diversity gain can be obtained on top of the advantages of spatial diversity. Here, since platforms

  5. Classification algorithms for weather radar

    Microsoft Academic Search

    Felix Yanovsky; Vitaly Marchuk; Yaroslav Ostrovsky; Yulia Averyanova

    2008-01-01

    Theory, measurements, and signal processing applying to the radar remote sensing of weather objects are considered. Algorithms for hydrometeor type and turbulence intensity recognition are developed and analyzed. Particularly, fuzzy logic and neural network approaches are applied for weather radar signal processing.

  6. Space Radar Images of Earth

    NSDL National Science Digital Library

    This collection of images was captured by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar, which was flown on two flights of the space shuttle Endeavour in 1994. Images are classified into categories for ease in searching: archaeological sites, cities, ecology and agriculture, geology, interferometry, oceans, rivers, snow and ice, and volcanoes.

  7. Radar background signal reduction study

    Microsoft Academic Search

    E. F. Knott; C. J. Ray; M. S. West; R. J. Wohlers

    1980-01-01

    This report summarizes a study whose objective was to identify materials and\\/or techniques to reduce radar background signals for ground plane radar cross section (RCS) ranges. Background signal reduction is essential for improving the accuracy of RCS measurements and the primary application is for operations at the RATSCAT range on the White Sands Missile Range in New Mexico. A survey

  8. A radar image time series

    NASA Technical Reports Server (NTRS)

    Leberl, F.; Fuchs, H.; Ford, J. P.

    1981-01-01

    A set of ten side-looking radar images of a mining area in Arizona that were aquired over a period of 14 yr are studied to demonstrate the photogrammetric differential-rectification technique applied to radar images and to examine changes that occurred in the area over time. Five of the images are rectified by using ground control points and a digital height model taken from a map. Residual coordinate errors in ground control are reduced from several hundred meters in all cases to + or - 19 to 70 m. The contents of the radar images are compared with a Landsat image and with aerial photographs. Effects of radar system parameters on radar images are briefly reviewed.

  9. Space-based radar handbook

    NASA Astrophysics Data System (ADS)

    Cantafio, Leopold J.

    The design and operation of space-based radar (SBR) systems are discussed in chapters contributed by leading experts. An overview of current and planned SBRs is presented, and particular attention is given to SBR-platform orbits, the ionospheric environment and its effects on SBR detection, space-based SARs, bistatic SBRs, rendezvous radars, radar altimeters for space vehicles, scatterometers and other modest-resolution systems, and thermal control for SBRs. Also considered are the radar cross sections of satellites and other space targets, SBR clutter and interference, space antenna technology, onboard radar-signal processors, space power systems, and SBR structures. Diagrams, drawings, graphs, maps, and tables of numerical data are provided.

  10. Radar image registration and rectification

    NASA Technical Reports Server (NTRS)

    Naraghi, M.; Stromberg, W. D.

    1983-01-01

    Two techniques for radar image registration and rectification are presented. In the registration method, a general 2-D polynomial transform is defined to accomplish the geometric mapping from one image into the other. The degree and coefficients of the polynomial are obtained using an a priori found tiepoint data set. In the second part of the paper, a rectification procedure is developed that models the distortion present in the radar image in terms of the radar sensor's platform parameters and the topographic variations of the imaged scene. This model, the ephemeris data and the digital topographic data are then used in rectifying the radar image. The two techniques are then used in registering and rectifying two examples of radar imagery. Each method is discussed as to its benefits, shortcomings and registration accuracy.

  11. Analysis of a free oscillation atom interferometer

    SciTech Connect

    Kafle, Rudra P.; Zozulya, Alex A. [Department of Physics, Worcester Polytechnic Institute, 100 Institute Road, Worcester, Massachusetts 01609 (United States); Anderson, Dana Z. [Department of Physics and JILA, University of Colorado and National Institute of Standards and Technology, Boulder, Colorado 80309-0440 (United States)

    2011-09-15

    We analyze a Bose-Einstein condensate (BEC)-based free oscillation atom Michelson interferometer in a weakly confining harmonic magnetic trap. A BEC at the center of the trap is split into two harmonics by a laser standing wave. The harmonics move in opposite directions with equal speeds and turn back under the influence of the trapping potential at their classical turning points. The harmonics are allowed to pass through each other and a recombination pulse is applied when they overlap at the end of a cycle after they return for the second time. We derive an expression for the contrast of the interferometric fringes and obtain the fundamental limit of performance of the interferometer in the parameter space.

  12. Phase-shifting point diffraction interferometer

    DOEpatents

    Medecki, H.

    1998-11-10

    Disclosed is a point diffraction interferometer for evaluating the quality of a test optic. In operation, the point diffraction interferometer includes a source of radiation, the test optic, a beam divider, a reference wave pinhole located at an image plane downstream from the test optic, and a detector for detecting an interference pattern produced between a reference wave emitted by the pinhole and a test wave emitted from the test optic. The beam divider produces separate reference and test beams which focus at different laterally separated positions on the image plane. The reference wave pinhole is placed at a region of high intensity (e.g., the focal point) for the reference beam. This allows reference wave to be produced at a relatively high intensity. Also, the beam divider may include elements for phase shifting one or both of the reference and test beams. 8 figs.

  13. Phase-shifting point diffraction interferometer

    DOEpatents

    Medecki, Hector (Berkeley, CA)

    1998-01-01

    Disclosed is a point diffraction interferometer for evaluating the quality of a test optic. In operation, the point diffraction interferometer includes a source of radiation, the test optic, a beam divider, a reference wave pinhole located at an image plane downstream from the test optic, and a detector for detecting an interference pattern produced between a reference wave emitted by the pinhole and a test wave emitted from the test optic. The beam divider produces separate reference and test beams which focus at different laterally separated positions on the image plane. The reference wave pinhole is placed at a region of high intensity (e.g., the focal point) for the reference beam. This allows reference wave to be produced at a relatively high intensity. Also, the beam divider may include elements for phase shifting one or both of the reference and test beams.

  14. Mosaicking with cosmic microwave background interferometers

    E-print Network

    Bunn, E F; Bunn, Emory F.; White, Martin

    2006-01-01

    Measurements of cosmic microwave background (CMB) anisotropies by interferometers offer several advantages over single-dish observations. The formalism for analyzing interferometer CMB data is well developed in the flat-sky approximation, valid for small fields of view. As the area of sky is increased to obtain finer spectral resolution, this approximation needs to be relaxed. We extend the formalism for CMB interferometry, including both temperature and polarization, to mosaics of observations covering arbitrarily large areas of the sky, with each individual pointing lying within the flat-sky approximation. We present a method for computing the correlation between visibilities with arbitrary pointing centers and baselines and illustrate the effects of sky curvature on the l-space resolution that can be obtained from a mosaic.

  15. Mosaicking with cosmic microwave background interferometers

    E-print Network

    Emory F. Bunn; Martin White

    2006-06-19

    Measurements of cosmic microwave background (CMB) anisotropies by interferometers offer several advantages over single-dish observations. The formalism for analyzing interferometer CMB data is well developed in the flat-sky approximation, valid for small fields of view. As the area of sky is increased to obtain finer spectral resolution, this approximation needs to be relaxed. We extend the formalism for CMB interferometry, including both temperature and polarization, to mosaics of observations covering arbitrarily large areas of the sky, with each individual pointing lying within the flat-sky approximation. We present a method for computing the correlation between visibilities with arbitrary pointing centers and baselines and illustrate the effects of sky curvature on the l-space resolution that can be obtained from a mosaic.

  16. Thermal-noise-limited underground interferometer CLIO

    NASA Astrophysics Data System (ADS)

    Agatsuma, Kazuhiro; Arai, Koji; Fujimoto, Masa-Katsu; Kawamura, Seiji; Kuroda, Kazuaki; Miyakawa, Osamu; Miyoki, Shinji; Ohashi, Masatake; Suzuki, Toshikazu; Takahashi, Ryutaro; Tatsumi, Daisuke; Telada, Souichi; Uchiyama, Takashi; Yamamoto, Kazuhiro; collaborators, CLIO

    2010-04-01

    We report on the current status of CLIO (Cryogenic Laser Interferometer Observatory), which is a prototype interferometer for LCGT (large scale cryogenic gravitational-wave telescope). LCGT is a Japanese next-generation interferometric gravitational-wave detector featuring the use of cryogenic mirrors and a quiet underground site. The main purpose of CLIO is to demonstrate a reduction of the mirror thermal noise by cooling the sapphire mirrors. CLIO is located in an underground site of the Kamioka mine, 1000 m deep from the mountain top, to verify its advantages. After a few years of commissioning work, we have achieved a thermal-noise-limited sensitivity at room temperature. One of the main results of noise hunting was the elimination of thermal noise caused by a conductive coil holder coupled with a pendulum through magnets.

  17. Interferometer for Low-Uncertainty Vector Metrology

    NASA Technical Reports Server (NTRS)

    Toland, Ronald W.; Leviton, Douglas B.

    2006-01-01

    A simplified schematic diagram of a tilt-sensing unequal-path interferometer set up to measure the orientation of the normal vector of one surface of a cube mounted on a structure under test is described herein. This interferometer has been named a "theoferometer" to express both its interferometric nature and the intention to use it instead of an autocollimating theodolite. The theoferometer optics are mounted on a plate, which is in turn mounted on orthogonal air bearings for near-360 rotation in azimuth and elevation. Rough alignment of the theoferometer to the test cube is done by hand, with fine position adjustment provided by a tangent arm drive using linear inchwormlike motors.

  18. FLUOR fibered instrument at the IOTA interferometer

    NASA Astrophysics Data System (ADS)

    Coudé du Foresto, Vincent; Perrin, Guy; Ruilier, Cyril; Mennesson, Bertrand P.; Traub, Wesley A.; Lacasse, Marc G.

    1998-07-01

    The FLUOR project started in 1991 with a prototype fiber recombination unit that transformed a pair of independent 80 cm telescopes into a stellar interferometer. An improved version of this unit is now used as part of the instrumentation at the IOTA interferometer on Mt. Hopkins. The system is based on fluoride glass single-mode waveguides for observations at IR wavelengths between 2 and 2.4 micrometers . A triple coupler performs the coherent recombination of the beams and extracts two calibration signals. A passive polarization control is sufficient to maintain the interferometric efficiency above 80 percent, with variations of the order of a few percents form one night to the next. The combination FLUOR/IOTA now routinely provides stellar interferograms on baselines ranging between 5 and 38 m, with an accuracy of 1 percent or better in the fringe visibility measurements.

  19. Broadband, Achromatic Twyman-Green Interferometer

    NASA Technical Reports Server (NTRS)

    Steimle, Lawrence J.

    1991-01-01

    Improved Twyman-Green interferometer used in wave-front testing optical components at wavelengths from 200 to 1,100 nm, without having to readjust focus when changing wavelength. Built to measure aberrations of light passing through optical filters. Collimating and imaging lenses of classical Twyman-Green configuration replaced by single spherical mirror. Field lens replaced by field mirror. Mirrors exhibit no axial chromatic aberration and made to reflect light efficiently over desired broad range of wavelengths.

  20. The lunar interferometer for solar physics

    NASA Astrophysics Data System (ADS)

    Dame, L.; Martic, M.; Porteneuve, J.; Schnur, G. F. O.

    1992-12-01

    The concept of a Lunar Interferometer for Solar Physics (LISP) is presented. The choice of a configuration for the imaging complex and the optical and mechanical design are discussed. Particular attention is paid to the rationale for a compact two dimensional array and the use of a novel mechanical support structure based on linear mounting rods is proposed. These two conceptual choices optimize imaging capacities and room and mass issues for transportation to the Moon.

  1. Scanning microwave interferometer for ELMO bumpy torus

    SciTech Connect

    Uckan, T.

    1983-10-01

    A simple 4-mm scanning microwave interferometer has been developed and employed for electron density profile measurements on the ELMO bumpy torus (EBT). By making use of a pair of horizontally moving 45/sup 0/ mirrors that are located at the top and bottom of the plasma volume, the system avoids the deleterious effects of plasma sputtering and wall material flaking, since the microwave transmission and receiving horns do not view the plasma directly.

  2. Frequency Swept 40 GHz Microwave Interferometer System

    Microsoft Academic Search

    J. W. Volock

    2005-01-01

    A swept frequency 40 Gigahertz Microwave Interferometer has been constructed to measure line-averaged electron density in the new HELCAT (HELicon-CAThode) plasma device at UNM. This system utilizes many custom circuits, including a 1MHz sawtooth wave generator with a sweepback time less than 50ns, bandpass filters, and IF amplifiers. The system also utilizes easily adaptable mounts we designed and built that

  3. Interferometers as probes of Planckian quantum geometry

    NASA Astrophysics Data System (ADS)

    Hogan, Craig J.

    2012-03-01

    A theory of position of massive bodies is proposed that results in an observable quantum behavior of geometry at the Planck scale, tP. Departures from classical world lines in flat spacetime are described by Planckian noncommuting operators for position in different directions, as defined by interactions with null waves. The resulting evolution of position wave functions in two dimensions displays a new kind of directionally coherent quantum noise of transverse position. The amplitude of the effect in physical units is predicted with no parameters, by equating the number of degrees of freedom of position wave functions on a 2D space-like surface with the entropy density of a black hole event horizon of the same area. In a region of size L, the effect resembles spatially and directionally coherent random transverse shear deformations on time scale ?L/c with typical amplitude ?ctPL. This quantum-geometrical “holographic noise” in position is not describable as fluctuations of a quantized metric, or as any kind of fluctuation, dispersion or propagation effect in quantum fields. In a Michelson interferometer the effect appears as noise that resembles a random Planckian walk of the beam splitter for durations up to the light-crossing time. Signal spectra and correlation functions in interferometers are derived, and predicted to be comparable with the sensitivities of current and planned experiments. It is proposed that nearly colocated Michelson interferometers of laboratory scale, cross-correlated at high frequency, can test the Planckian noise prediction with current technology.

  4. Tunneling current through fractional quantum Hall interferometers

    NASA Astrophysics Data System (ADS)

    Smits, O.; Slingerland, J. K.; Simon, S. H.

    2014-01-01

    We calculate the tunneling current through a Fabry-Pérot interferometer in the fractional quantum Hall regime. Within linear response theory (weak tunneling but arbitrary source-drain voltage), we find a general expression for the current due to tunneling of quasiparticles in terms of Carlson's R function. Our result is valid for fractional quantum Hall states with an edge theory consisting of a charged channel and any number of neutral channels, with possibly different edge velocities and different chiralities. We analyze the case with a single neutral channel in detail, which applies for instance to the edge of the Moore-Read state. In addition, we consider an asymmetric interferometer with different edge lengths between the point contacts on opposite edges, and we study the behavior of the current as a function of varying edge length. Recent experiments attempted to measure the Aharanov-Bohm effect by changing the area inside the interferometer using a plunger gate. Theoretical analyses of these experiments have so far not taken into account the accompanying change in the edge lengths. We show that the tunneling current exhibits multiple oscillations as a function of this edge length, with frequencies proportional to the injected edge current and inversely proportional to the edge velocities. In particular, the edge velocities can be measured by looking at the Fourier spectrum of the edge current. We provide a numerical scheme to calculate and plot the R function, and include sample plots for a variety of edge states with parameter values, which are experimentally relevant.

  5. Hybrid photonic chip interferometer for embedded metrology

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Martin, H.; Maxwell, G.; Jiang, X.

    2014-03-01

    Embedded metrology is the provision of metrology on the manufacturing platform, enabling measurement without the removal of the work piece. Providing closer integration of metrology upon the manufacturing platform can lead to the better control and increased throughput. In this work we present the development of a high precision hybrid optical chip interferometer metrology device. The complete metrology sensor system is structured into two parts; optical chip and optical probe. The hybrid optical chip interferometer is based on a silica-on-silicon etched integrated-optic motherboard containing waveguide structures and evanescent couplers. Upon the motherboard, electro-optic components such as photodiodes and a semiconductor gain block are mounted and bonded to provide the required functionality. The key structure in the device is a tunable laser module based upon an external-cavity diode laser (ECDL). Within the cavity is a multi-layer thin film filter which is rotated to select the longitudinal mode at which the laser operates. An optical probe, which uses a blazed diffracting grating and collimating objective lens, focuses light of different wavelengths laterally over the measurand. Incident laser light is then tuned in wavelength time to effectively sweep an `optical stylus' over the surface. Wavelength scanning and rapid phase shifting can then retrieve the path length change and thus the surface height. We give an overview of the overall design of the final hybrid photonic chip interferometer, constituent components, device integration and packaging as well as experimental test results from the current version now under evaluation.

  6. An improved radar detection range plotting method based on radar equation

    Microsoft Academic Search

    Li-Wei Wang; Xiao-Song Jiang

    2011-01-01

    In this paper, an improved radar detection range plotting method based on radar equation is proposed. Radar equation can be used to plot the radar detection range in theory from the point of view of energy. But in practice, the condition can not be satisfied. Based on radar equation, this method takes ground reflection, atmospheric refraction, earth curvature and obstacle

  7. Understanding Radar Refractivity: Sources of Uncertainty

    E-print Network

    Droegemeier, Kelvin K.

    Understanding Radar Refractivity: Sources of Uncertainty David Bodine1,2 , Dan Michaud1,2 , Robert Radar Research Center, University of Oklahoma, Norman, OK, USA 3 NOAA/OAR National Severe Storms validation of WSR-88D radar refractiv- ity retrievals, and discusses some challenges to implementing radar

  8. Shuttle rendezvous radar performance: evaluation and simulation

    Microsoft Academic Search

    J. W. Griffin; A. C. Lindberg; T. B. Ahn; P. L. Harton

    1989-01-01

    The authors describe the performance evaluation and simulation of the Ku-band shuttle rendezvous radar. Computer simulation, using the radar cross section for specific spacecraft, provided an estimate of rendezvous radar range performance for that spacecraft. The radar cross section model included smooth metallic surfaces, rough surfaces, and shadowing effects, as well as phase differences due to different path lengths to

  9. Evaluation of high frequency radar wave measurement

    Microsoft Academic Search

    L. R Wyatt; S. P Thompson; R. R Burton

    1999-01-01

    The spatial coverage, temporal availability and spectral and parameter accuracy of wave measurements using radars operating at the upper end of the high frequency (HF) radio band are discussed. The two radars used are the Ocean Surface Current Radar (OSCR) developed in the UK and the Wellen Radar (WERA) developed in Germany. The measurements show that useful accuracy is obtainable

  10. Soviet oceanographic synthetic aperture radar (SAR) research

    Microsoft Academic Search

    D. N. Held; R. F. Gasparovic; A. W. Mansfield; W. K. Melville; E. L. Mollo-Christensen; H. A. Zebker

    1991-01-01

    Radar non-acoustic anti-submarine warfare (NAASW) became the subject of considerable scientific investigation and controversy in the West subsequent to the discovery by the Seasat satellite in 1978 that manifestations of underwater topography, thought to be hidden from the radar, were visible in synthetic aperture radar (SAR) images of the ocean. In addition, the Seasat radar produced images of ship wakes

  11. The applicability of GMTI MIMO Radar

    Microsoft Academic Search

    Michael Zatman

    2010-01-01

    MIMO Radar has been proposed as a technique for improving the Minimum Detectable Velocity (MDV) performance of airborne radar systems. However, the increased pulse repetition frequency associated with waveform multiplexing techniques used in GMTI MIMO Radar increases the amount of range ambiguous clutter the radar must suppress, reducing the amount of clutter-free Doppler space available to detect targets and often

  12. Electron density profile measurement using an ultrashort-pulsed radar reflectometer on large helical device

    SciTech Connect

    Kaneba, T.; Tokuzawa, T.; Kawahata, K.; Ito, Y.; Nagayama, Y. [Department of Fusion Science, School of Mathematical and Physical Science, Graduate University for Advanced Studies, Hayama 240-0193 (Japan); National Institute for Fusion Science, Toki 509-5292 (Japan)

    2004-10-01

    We have installed a six channel ultrashort-pulsed radar reflectometer system on the large helical device and performed electron density profile measurements. The delay time of the reflected pulses from each cutoff layer in the plasma is measured by a time-of-flight measurement technique in order to avoid the mixture of radiation effects and spurious reflections. The electron density profile is reconstructed using an Abel inversion method from the profile of the delay time as a function of the probing frequency. The reconstructed density profile is compared with the profile measured with the far-infrared (FIR) interferometer. It is found that the arrival time of each reflected pulse differs from the estimated time measured with the FIR interferometer.

  13. Large phased-array radars

    SciTech Connect

    Brookner, D.E.

    1988-12-15

    Large phased-array radars can play a very important part in arms control. They can be used to determine the number of RVs being deployed, the type of targeting of the RVs (the same or different targets), the shape of the deployed objects, and possibly the weight and yields of the deployed RVs. They can provide this information at night as well as during the day and during rain and cloud covered conditions. The radar can be on the ground, on a ship, in an airplane, or space-borne. Airborne and space-borne radars can provide high resolution map images of the ground for reconnaissance, of anti-ballistic missile (ABM) ground radar installations, missile launch sites, and tactical targets such as trucks and tanks. The large ground based radars can have microwave carrier frequencies or be at HF (high frequency). For a ground-based HF radar the signal is reflected off the ionosphere so as to provide over-the-horizon (OTH) viewing of targets. OTH radars can potentially be used to monitor stealth targets and missile traffic.

  14. Large phased-array radars

    NASA Astrophysics Data System (ADS)

    Brookner, Eli, Dr.

    1988-12-01

    Large phased-array radars can play a very important part in arms control. They can be used to determine the number of RVs being deployed, the type of targeting of the RVs (the same or different targets), the shape of the deployed objects, and possibly the weight and yields of the deployed RVs. They can provide this information at night as well as during the day and during rain and cloud covered conditions. The radar can be on the ground, on a ship, in an airplane, or space-borne. Airborne and space-borne radars can provide high resolution map images of the ground for reconnaissance, of anti-ballistic missile (ABM) ground radar installations, missile launch sites, and tactical targets such as trucks and tanks. The large ground based radars can have microwave carrier frequencies or be at HF (high frequency). For a ground-based HF radar the signal is reflected off the ionosphere so as to provide over-the-horizon (OTH) viewing of targets. OTH radars can potentially be used to monitor stealth targets and missile traffic.

  15. Automatic Adjustments of a Michelson Interferometer Using Genetic Algorithms

    NASA Astrophysics Data System (ADS)

    Nosato, Hirokazu; Sasage, Toshimichi; Murakawa, Masahiro; Itatani, Taro; Higuchi, Tetsuya; Furuya, Tatsumi

    This paper describes automatic adjustment of a michelson interferometer using genetic algorithms. The michelson interferometer consists of optical components (such as mirrors, lens, and prisms) that must be physically positioned with micron-meter precision to obtain optimal performance. Therefore, it is very difficult to use an interferometer outside for environmental measurement such as air pollution, because outside use causes mis-alignment of optical components. In order to overcome this problem, we propose automatic adjustment method using genetic algorithms that realize the optimal and quick alignment of optical components of interferometer. We also develop new compact mirror holder that allows portable and on-site use of interferometer. We confirmed the advantage of this system by the comparison with conventional adjustment algorithms. The proposed interferometer including the new compact mirror holders has been successfully adjusted by genetic algorithm in three minutes. The quick adjustment time indicates the possibility that the system can be used for on-site measurement.

  16. Refractometric sensor based on all-fiber coaxial Michelson interferometers

    NASA Astrophysics Data System (ADS)

    Barrios, Paola; Sáez-Rodríguez, David; Rodríguez, Amparo; Cruz, José L.; Díez, Antonio; Andrés, Miguel V.

    2009-05-01

    All-fiber coaxial Michelson interferometers are compact and very stable interferometers that can be dipped directly into water solutions for chemical and biological sensing. The sensitivity of the cladding mode to the surrounding medium can be exploited to use the interferometer as a compact fiber refractometer. Several interferometers have been fabricated and characterized as glucose sensors. A first series of devices were designed to work at 1550 nm, while a second series was prepared to work at 850 nm. Thus, the second series of interferometers enables the use of compact, robust and low cost optical spectrum analyzers. In our present experiments, the length of the fiber that forms the interferometer was within the range 1-10 cm. When the shift of the spectrum maxima were measured as a function of the glucose concentration, a slope of 350 pm/% was achieved. The use of the 850 nm sensor heads as a portable sensor system to monitor sewage treatment plants is shown.

  17. Development of stable monolithic wide-field Michelson interferometers.

    PubMed

    Wan, Xiaoke; Ge, Jian; Chen, Zhiping

    2011-07-20

    Bulk wide-field Michelson interferometers are very useful for high precision applications in remote sensing and astronomy. A stable monolithic Michelson interferometer is a key element in high precision radial velocity (RV) measurements for extrasolar planets searching and studies. Thermal stress analysis shows that matching coefficients of thermal expansion (CTEs) is a critical requirement for ensuring interferometer stability. This requirement leads to a novel design using BK7 and LAK7 materials, such that the monolithic interferometer is free from thermal distortion. The processes of design, fabrication, and testing of interferometers are described in detail. In performance evaluations, the field angle is typically 23.8° and thermal sensitivity is typically -2.6×10(-6)/°C near 550 nm, which corresponds to ?800 m/s/°C in the RV scale. Low-cost interferometer products have been commissioned in multiple RV instruments, and they are producing high stability performance over long term operations. PMID:21772398

  18. Compensation for the Variable Cyclic Error in Homodyne Laser Interferometers

    PubMed Central

    Hu, Pengcheng; Zhu, Jinghao; Guo, Xuanbiao; Tan, Jiubin

    2015-01-01

    This paper presents a real-time method to compensate for the variable cyclic error in a homodyne laser interferometer. The parameters describing the quadrature signals of the interferometer are estimated using simple peak value detectors. The cyclic error in the homodyne laser interferometer was then corrected through simple arithmetic calculations of the quadrature signals. A field programmable gate array was utilized for the real-time compensation of the cyclic error in a homodyne laser interferometer. The simulation and experimental results indicated that the proposed method could provide a cyclic error that was fixed without compensation down to a value under 0.6 nm in a homodyne laser interferometer. The proposed method could also reduce the time-varying cyclic error to a value under 0.6 nm in a homodyne laser interferometer, in contrast to the equivalent value of 13.3 nm for a conventional elliptical fitting method. PMID:25647739

  19. Special topics in infrared interferometry. [Michelson interferometer development

    NASA Technical Reports Server (NTRS)

    Hanel, R. A.

    1985-01-01

    Topics in IR interferometry related to the development of a Michelson interferometer are treated. The selection and reading of the signal from the detector to the analog to digital converter is explained. The requirements for the Michelson interferometer advance speed are deduced. The effects of intensity modulation on the interferogram are discussed. Wavelength and intensity calibration of the interferometer are explained. Noise sources (Nyquist or Johnson noise, phonon noise), definitions of measuring methods of noise, and noise measurements are presented.

  20. A Comparison of Structurally Connected and Multiple Spacecraft Interferometers

    NASA Technical Reports Server (NTRS)

    Surka, Derek M.; Crawley, Edward F.

    1996-01-01

    Structurally connected and multiple spacecraft interferometers are compared in an attempt to establish the maximum baseline (referred to as the "cross-over baseline") for which it is preferable to operate a single-structure interferometer in space rather than an interferometer composed of numerous, smaller spacecraft. This comparison is made using the total launched mass of each configuration as the comparison metric. A framework of study within which structurally connected and multiple spacecraft interferometers can be compared is presented in block diagram form. This methodology is then applied to twenty-two different combinations of trade space parameters to investigate the effects of different orbits, orientations, truss materials, propellants, attitude control actuators, onboard disturbance sources, and performance requirements on the cross-over baseline. Rotating interferometers and the potential advantages of adding active structural control to the connected truss of the structurally connected interferometer are also examined. The minimum mass design of the structurally connected interferometer that meets all performance-requirements and satisfies all imposed constraints is determined as a function of baseline. This minimum mass design is then compared to the design of the multiple spacecraft interferometer. It is discovered that the design of the minimum mass structurally connected interferometer that meets all performance requirements and constraints in solar orbit is limited by the minimum allowable aspect ratio, areal density, and gage of the struts. In the formulation of the problem used in this study, there is no advantage to adding active structural control to the truss for interferometers in solar orbit. The cross-over baseline for missions of practical duration (ranging from one week to thirty years) in solar orbit is approximately 400 m for non-rotating interferometers and 650 m for rotating interferometers.

  1. Electro-optical Tuning of Fabry-Perot Interferometers

    NASA Technical Reports Server (NTRS)

    Schwemmer, G. K.

    1986-01-01

    Compact unit operates much faster than conventional piezoelectric scanners. High voltage creates electric field in Pockels cell, changing refractive properties. Cell changes optical path length between mirrors without mechanically moving anything in gap. High voltage varied rapidly to scan interferometer. Voltage applied longitudinally or transversely, depending on type of Pockels cell. New electro-optic scanner scans given range in one-millionth time of piezoelectric scanner - tens to hundreds of nanoseconds per interferometer order. Also reducing size of interferometer.

  2. Historical aspects of radar atmospheric dynamics

    NASA Technical Reports Server (NTRS)

    Kato, Susumu

    1989-01-01

    A review of the history of radar techniques which have been applied to atmospheric observation is given. The author starts with ionosphere observation with the ionosonde, symbolizing as it does the earliest history of radar observation, and proceeds to later developments in radar observation such as the use of partial reflection, meteor, and incoherent scatter radars. Mesosphere stratosphere troposphere (MST) radars are discussed in terms of lower atmosphere observation.

  3. Imaging radar applications to mapping and charting

    NASA Technical Reports Server (NTRS)

    Leberl, F.

    1976-01-01

    The paper outlines the major actual and potential radar mapping applications, gives an account of the present state of satellite radar imaging, and reviews the radargrammetric work achieved since 1972. Attention is focused on the mapping methods and accuracy regarding single-image radar mapping, stereo radargrammetry, and mapping from blocks of overlapping imagery. It is recommended that more radargrammetric expertise be applied in radar mapping projects so that full advantage may be taken of the metric information potential of imaging radar.

  4. The Clementine bistatic radar experiment.

    PubMed

    Nozette, S; Lichtenberg, C L; Spudis, P; Bonner, R; Ort, W; Malaret, E; Robinson, M; Shoemaker, E M

    1996-11-29

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole. PMID:8929403

  5. The Clementine bistatic radar experiment

    USGS Publications Warehouse

    Nozette, S.; Lichtenberg, C.L.; Spudis, P.; Bonner, R.; Ort, W.; Malaret, E.; Robinson, M.; Shoemaker, E.M.

    1996-01-01

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, ??, for selected lunar areas. Observations of the lunar south pole yield a same- sense polarization enhancement around ?? = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole.

  6. Space Radar Images of Earth

    NSDL National Science Digital Library

    Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR), part of NASA's Mission to Planet Earth, is studying how our global environment is changing. From the unique vantage point of space, the radar system observes, monitors and assesses large-scale environmental processes with a focus on climate change. The spaceborne data, complemented by aircraft and ground studies, gives scientists highly detailed information that will help them distinguish natural environmental changes from those that are the result of human activity. The images are divided into nine categories for easier viewing.

  7. The Clementine Bistatic Radar Experiment

    NASA Technical Reports Server (NTRS)

    Nozette, S.; Lichtenberg, C. L.; Spudis, P.; Bonner, R.; Ort, W.; Malaret, E.; Robinson, M.; Shoemaker, E. M.

    1996-01-01

    During the Clementine 1 mission, a bistatic radar experiment measured the magnitude and polarization of the radar echo versus bistatic angle, beta, for selected lunar areas. Observations of the lunar south pole yield a same-sense polarization enhancement around beta = 0. Analysis shows that the observed enhancement is localized to the permanently shadowed regions of the lunar south pole. Radar observations of periodically solar-illuminated lunar surfaces, including the north pole, yielded no such enhancement. A probable explanation for these differences is the presence of low-loss volume scatterers, such as water ice, in the permanently shadowed region at the south pole.

  8. Quantum heat engines based on electronic Mach-Zehnder interferometers

    NASA Astrophysics Data System (ADS)

    Hofer, Patrick P.; Sothmann, Björn

    2015-05-01

    We theoretically investigate the thermoelectric properties of heat engines based on Mach-Zehnder interferometers. The energy dependence of the transmission amplitudes in such setups arises from a difference in the interferometer arm lengths. Any thermoelectric response is thus of purely quantum-mechanical origin. In addition to an experimentally established three-terminal setup, we also consider a two-terminal geometry as well as a four-terminal setup consisting of two interferometers. We find that Mach-Zehnder interferometers can be used as powerful and efficient heat engines which perform well under realistic conditions.

  9. Regenerative processes in a radio-frequency Josephson interferometer

    SciTech Connect

    Gusev, A.V.; Rudenko, V.N.

    1985-01-01

    Phase modulation of rf oscillations in a Josephson interferometer with hysteresis is described theoretically outside the plateau in the voltage-current characteristic. A generalized phenomenological model is developed for the magnetic flux quantum jumps in interferometers which treats the phase change produced by external perturbations and fluctuations. The forced oscillations become unstable when the coupling between the interferometer loop and the pumping channel reaches a certain value. The application of this instability to maximizing the sensitivity of quantum rf interferometers (so that the sensitivity is limited only by the constraints imposed by fluctuations in the Josephson contact) is discussed.

  10. Nonlocal labeling of paths in a single-photon interferometer

    SciTech Connect

    Pysher, M. J.; Galvez, E. J.; Misra, K.; Wilson, K. R.; Melius, B. C.; Malik, M. [Department of Physics and Astronomy, Colgate University, Hamilton, NY 13346 (United States)

    2005-11-15

    We prepared polarization-entangled photon pairs and sent one of the photons through a Mach-Zehnder interferometer. The apparatus was arranged so that when going through each arm of the interferometer the pairs were in a different Bell state. The distinguishability of the interferometer paths was determined by projecting the entangled state of the two photons with a polarizer placed in the path of the photon that does not go through the interferometer. As a consequence, actions on the remote photon determined nonlocally the visibility of the interference pattern. We present a full theoretical analysis and experimental results that confirm the theoretical predictions.

  11. Airborne bistatic radar applications

    NASA Astrophysics Data System (ADS)

    Foster, James A.

    1987-09-01

    Applications of bistatic radar when one or both of the units are airborne are discussed. Scenarios that merit deeper consideration are covert strike and head-on SAR using a stand-off illuminator, either airborne or space-based; area air defense with passive ground-based receivers and stand-off illuminators; an airborne picket line to detect stealth aircraft and missiles; AWACS aircraft providing mutual support in ECM environments; and passive surveillance of hostile air space using illuminators of opportunity and an airborne receiver. Scenarios considered impractical are bistatic air-to-air missile guidance using an aircraft other than the launch aircraft as illuminator; passive interdiction using illuminators of opportunity; and scenarios involving a ground based illuminator and an aircraft as the receiver.

  12. Radar backscatter modelling

    NASA Astrophysics Data System (ADS)

    Schaber, G. G.; Kozak, R. C.; Gurule, R. L.

    1984-04-01

    The terrain analysis software package was restructured and documentation was added. A program was written to test Johnson Space Center's four band scatterometer data for spurious signals data. A catalog of terrain roughness statistics and calibrated four frequency multipolarization scatterometer data is being published to support the maintenance of Death Valley as a radar backscatter calibration test site for all future airborne and spacecraft missions. Test pits were dug through sand covered terrains in the Eastern Sahara to define the depth and character of subsurface interfaces responsible for either backscatter or specular response in SIR-A imagery. Blocky sandstone bedrock surfaces at about 1 m depth were responsible for the brightest SIR-A returns. Irregular very dense CaCO3 cemented sand interfaces were responsible for intermediate grey tones. Ancient river valleys had the weakest response. Reexamination of SEASAT l-band imagery of U.S. deserts continues.

  13. Fly eye radar or micro-radar sensor technology

    NASA Astrophysics Data System (ADS)

    Molchanov, Pavlo; Asmolova, Olga

    2014-05-01

    To compensate for its eye's inability to point its eye at a target, the fly's eye consists of multiple angularly spaced sensors giving the fly the wide-area visual coverage it needs to detect and avoid the threats around him. Based on a similar concept a revolutionary new micro-radar sensor technology is proposed for detecting and tracking ground and/or airborne low profile low altitude targets in harsh urban environments. Distributed along a border or around a protected object (military facility and buildings, camp, stadium) small size, low power unattended radar sensors can be used for target detection and tracking, threat warning, pre-shot sniper protection and provides effective support for homeland security. In addition it can provide 3D recognition and targets classification due to its use of five orders more pulses than any scanning radar to each space point, by using few points of view, diversity signals and intelligent processing. The application of an array of directional antennas eliminates the need for a mechanical scanning antenna or phase processor. It radically decreases radar size and increases bearing accuracy several folds. The proposed micro-radar sensors can be easy connected to one or several operators by point-to-point invisible protected communication. The directional antennas have higher gain, can be multi-frequency and connected to a multi-functional network. Fly eye micro-radars are inexpensive, can be expendable and will reduce cost of defense.

  14. Ambient vibration testing of bridges by microwave interferometer

    Microsoft Academic Search

    Gaetano De Pasquale; Giulia Bernardini; Pier Paolo Ricci; Carmelo Gentile

    2009-01-01

    Recent progress in radar techniques and systems led to the development of an interferometric radar suitable to the application in dynamic testing and vibration monitoring of civil engineering structures. The main characteristic of the new radar system is the possibility of simultaneously measuring the (static or dynamic) displacement of several points of a structure with high sensitivity. This describes the

  15. Measuring Cyclic Error in Laser Heterodyne Interferometers

    NASA Technical Reports Server (NTRS)

    Ryan, Daniel; Abramovici, Alexander; Zhao, Feng; Dekens, Frank; An, Xin; Azizi, Alireza; Chapsky, Jacob; Halverson, Peter

    2010-01-01

    An improved method and apparatus have been devised for measuring cyclic errors in the readouts of laser heterodyne interferometers that are configured and operated as displacement gauges. The cyclic errors arise as a consequence of mixing of spurious optical and electrical signals in beam launchers that are subsystems of such interferometers. The conventional approach to measurement of cyclic error involves phase measurements and yields values precise to within about 10 pm over air optical paths at laser wavelengths in the visible and near infrared. The present approach, which involves amplitude measurements instead of phase measurements, yields values precise to about .0.1 microns . about 100 times the precision of the conventional approach. In a displacement gauge of the type of interest here, the laser heterodyne interferometer is used to measure any change in distance along an optical axis between two corner-cube retroreflectors. One of the corner-cube retroreflectors is mounted on a piezoelectric transducer (see figure), which is used to introduce a low-frequency periodic displacement that can be measured by the gauges. The transducer is excited at a frequency of 9 Hz by a triangular waveform to generate a 9-Hz triangular-wave displacement having an amplitude of 25 microns. The displacement gives rise to both amplitude and phase modulation of the heterodyne signals in the gauges. The modulation includes cyclic error components, and the magnitude of the cyclic-error component of the phase modulation is what one needs to measure in order to determine the magnitude of the cyclic displacement error. The precision attainable in the conventional (phase measurement) approach to measuring cyclic error is limited because the phase measurements are af-

  16. VISAR (Velocity Interferometer System for Any Reflector): Line-imaging interferometer

    Microsoft Academic Search

    W. F. Hemsing; A. R. Mathews; R. H. Warnes; G. R. Whittemore

    1990-01-01

    This paper describes a Velocity Interferometer System for Any Reflector (VISAR) technique that extends velocity measurements from single points to a line. Single-frequency argon laser light was focused through a cylindrical lens to illuminate a line on a surface. The initially stationary, flat surface was accelerated unevenly during the experiment. Motion produced a Doppler-shift of light reflected from the surface

  17. Advanced Borehole Radar for Hydrogeology

    NASA Astrophysics Data System (ADS)

    Sato, M.

    2014-12-01

    Ground Penetrating Radar is a useful tool for monitoring the hydrogeological environment. We have developed GPR systems which can be applied to these purposes, and we will demonstrate examples borehole radar measurements. In order to have longer radar detection range, frequency lower than100MHz has been normally adopted in borehole radar. Typical subsurface fractures of our interests have a few mm aperture and radar resolution is much poorer than a few cm in this frequency range. We are proposing and demonstrating to use radar polarimetry to solve this problem. We have demonstrated that a full-polarimetry borehole radar can be used for characterization of subsurface fractures. Together with signal processing for antenna characteristic compensation to equalize the signal by a dipole antenna and slot antennas, we could demonstrate that polarimetric borehole radar can estimate the surface roughness of subsurface fractures, We believe the surface roughness is closely related to water permeability through the fractures. We then developed a directional borehole radar, which uses optical field sensor. A dipole antenna in a borehole has omni-directional radiation pattern, and we cannot get azimuthal information about the scatterers. We use multiple dipole antennas set around the borehole axis, and from the phase differences, we can estimate the 3-diemnational orientation of subsurface structures. We are using optical electric field sensor for receiver of borehole radar. This is a passive sensor and connected only with optical fibers and does not require any electric power supply to operate the receiver. It has two major advantages; the first one is that the receiver can be electrically isolated from other parts, and wave coupling to a logging cable is avoided. Then, secondary, it can operate for a long time, because it does not require battery installed inside the system. It makes it possible to set sensors in fixed positions to monitor the change of environmental conditions for a long period. We demonstrated this idea using cross- hole borehole radar measurement. We think this method is useful for detecting any changes in hydrogeological situations, which will be useful for subsurface storage such as LNG and nuclear waste.

  18. Micro-Precision Interferometer: Pointing Control System

    NASA Technical Reports Server (NTRS)

    O'Brien, John

    1995-01-01

    This paper describes the development of the wavefront tilt (pointing) control system for the JPL Micro-Precision Interferometer (MPI). This control system employs piezo-electric actuators and a digital imaging sensor with feedback compensation to reject errors in instrument pointing. Stringent performance goals require large feedback, however, several characteristics of the plant tend to restrict the available bandwidth. A robust 7th-order wavefront tilt control system was successfully implemented on the MPI instrument, providing sufficient disturbance rejection performance to satisfy the established interference fringe visibility.

  19. Third telescope project at the IOTA interferometer

    NASA Astrophysics Data System (ADS)

    Traub, Wesley A.; Carleton, Nathaniel P.; Bregman, Jesse D.; Brewer, M. K.; Lacasse, Marc G.; Maymounkov, P.; Millan-Gabet, Rafael; Monnier, John D.; Morel, Sebastien; Papaliolios, Costas D.; Pearlman, Michael R.; Porro, Irene L.; Schloerb, F. Peter; Souccar, Kamal

    2000-07-01

    The third telescope project to enable phase-closure observations at the IOTA interferometer is well underway, and is anticipated to be completed later this year. For this project, we present the main technical improvements which we have already made or expect to make, including a new VxWorks control system, improved star acquisition cameras, improved siderostat and primary mirror supports, five-axis control of the telescope secondary mirrors, automated control of the long delay line, trihedral retroreflectors, three-beam combination, the PICNIC camera, and fringe packet tracking.

  20. Mapping surface winds using ocean acoustic interferometers

    NASA Astrophysics Data System (ADS)

    Voronovich, A.; Penland, C.

    2008-12-01

    We discuss the feasibility of using an acoustic interferometer consisting of a pair of acoustic hydrophones separated horizontally by a few tens of kilometers to diagnose the location and intensity of noise generated by tropical cyclones. Since the intensity of noise is strongly dependent on wind, noise mapping is essentially equivalent to wind mapping. The method is based on coherent processing of a broadband ambient noise within a frequency band of tens of Hertz. We demonstrate that resolution of the order of a few kilometers, at distances of the order of a thousand kilometers, is achievable in principle. An estimate of the signal to noise ratio is also provided.

  1. Radar imaging of Saturn's rings

    Microsoft Academic Search

    Philip D. Nicholson; Richard G. French; Donald B. Campbell; Jean-Luc Margot; Michael C. Nolan; Gregory J. Black; Heikki J. Salo

    2005-01-01

    We present delay–Doppler images of Saturn's rings based on radar observations made at Arecibo Observatory between 1999 and 2003, at a wavelength of 12.6 cm and at ring opening angles of 20.1°?|B|?26.7°. The average radar cross-section of the A ring is ?77% relative to that of the B ring, while a stringent upper limit of 3% is placed on the

  2. Rendezvous radar for orbital vehicles

    NASA Astrophysics Data System (ADS)

    Locke, John W.; Casey, Larry D.

    1992-03-01

    In this paper some of the factors which relate to the system design of rendezvous radars are discussed and the system design and the capabilities of the OMV Rendezvous Radar System (RRS) are described. The potential for transferring manufacturing technologies and methods which have been developed for high-volume-production commercial and military hardware systems into the relatively low volume world of hi-rel electronics hardware for space is discussed.

  3. The NASA Polarimetric Radar (NPOL)

    NASA Technical Reports Server (NTRS)

    Petersen, Walter A.; Wolff, David B.

    2013-01-01

    Characteristics of the NASA NPOL S-band dual-polarimetric radar are presented including its operating characteristics, field configuration, scanning capabilities and calibration approaches. Examples of precipitation science data collections conducted using various scan types, and associated products, are presented for different convective system types and previous field campaign deployments. Finally, the NASA NPOL radar location is depicted in its home base configuration within the greater Wallops Flight Facility precipitation research array supporting NASA Global Precipitation Measurement Mission ground validation.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Radar reflectivity calibration using differential propagation phase measurement

    E-print Network

    Zhang, Guifu

    Radar reflectivity calibration using differential propagation phase measurement J. Vivekanandan,1 reflectivity using polarization radar measurements in rain is described. Accurate calibration of radar reflectivity is essential for obtaining reliable rain rate estimation. In the case of polarization radar, rain

  6. Testing Gravity with Cold-Atom Interferometers

    E-print Network

    G. W. Biedermann; X. Wu; L. Deslauriers; S. Roy; C. Mahadeswaraswamy; M. A. Kasevich

    2014-12-10

    We present a horizontal gravity gradiometer atom interferometer for precision gravitational tests. The horizontal configuration is superior for maximizing the inertial signal in the atom interferometer from a nearby proof mass. In our device, we have suppressed spurious noise associated with the horizonal configuration to achieve a differential acceleration sensitivity of 4.2$\\times10^{-9}g/\\sqrt{Hz}$ over a 70 cm baseline or 3.0$\\times10^{-9}g/\\sqrt{Hz}$ inferred per accelerometer. Using the performance of this instrument, we characterize the results of possible future gravitational tests. We complete a proof-of-concept measurement of the gravitational constant with a precision of 3$\\times10^{-4}$ that is competitive with the present limit of 1.2$\\times10^{-4}$ using other techniques. From this measurement, we provide a statistical constraint on a Yukawa-type fifth force at 8$\\times$10$^{-3}$ near the poorly known length scale of 10 cm. Limits approaching 10$^{-5}$ appear feasible. We discuss improvements that can enable uncertainties falling well below 10$^{-5}$ for both experiments.

  7. Testing gravity with cold-atom interferometers

    NASA Astrophysics Data System (ADS)

    Biedermann, G. W.; Wu, X.; Deslauriers, L.; Roy, S.; Mahadeswaraswamy, C.; Kasevich, M. A.

    2015-03-01

    We present a horizontal gravity gradiometer atom interferometer for precision gravitational tests. The horizontal configuration is superior for maximizing the inertial signal in the atom interferometer from a nearby proof mass. In our device, we have suppressed spurious noise associated with the horizonal configuration to achieve a differential acceleration sensitivity of 4.2 ×10-9g /?{Hz } over a 70-cm baseline or 3.0 ×10-9g /?{Hz } inferred per accelerometer. Using the performance of this instrument, we characterize the results of possible future gravitational tests. We demonstrate a statistical uncertainty of 3 ×10-4 for a proof-of-concept measurement of the gravitational constant that is competitive with the present limit of 1.2 ×10-4 using other techniques. From this measurement, we provide a statistical constraint on a Yukawa-type fifth force at 8 ×10-3 near the poorly known length scale of 10 cm. Limits approaching 10-5 appear feasible. We discuss improvements that can enable uncertainties falling well below 10-5 for both experiments.

  8. The millimeter-wave bolometric interferometer (MBI)

    NASA Astrophysics Data System (ADS)

    Tucker, Gregory S.; Korotkov, Andrei L.; Gault, Amanda C.; Hyland, Peter O.; Malu, Siddharth; Timbie, Peter T.; Bunn, Emory F.; Keating, Brian G.; Bierman, Evan; O'Sullivan, Créidhe; Ade, Peter A. R.; Piccirillo, Lucio

    2008-07-01

    We report on the design and tests of a prototype of the Millimeter-wave Bolometric Interferometer (MBI). MBI is designed to make sensitive measurements of the polarization of the cosmic microwave background (CMB). It combines the differencing capabilities of an interferometer with the high sensitivity of bolometers at millimeter wavelengths. The prototype, which we call MBI-4, views the sky directly through four corrugated horn antennas. MBI ultimately will have ~ 1000 antennas. These antennas have low sidelobes and nearly symmetric beam patterns, so spurious instrumental polarization from reflective optics is avoided. The MBI-4 optical band is defined by filters with a central frequency of 90 GHz. The set of baselines, determined by placement of the four antennas, results in sensitivity to CMB polarization fluctuations over the multipole range l = 150 - 270. The signals are combined with a Fizeau beam combiner and interference fringes are detected by an array of spider-web bolometers. In order to separate the visibility signals from the total power detected by each bolometer, the phase of the signal from each antenna is modulated by a ferrite-based waveguide phase shifter. Initial tests and observations have been made at Pine Bluff Observatory (PBO) outside Madison, WI.

  9. The Millimeter-Wave Bolometric Interferometer

    NASA Astrophysics Data System (ADS)

    Korotkov, Andrei; Ade, P. A.; Ali, S.; Bierman, E.; Bunn, E. F.; Calderon, C.; Gault, A. C.; Hyland, P. O.; Keating, B. G.; Kim, J.; Malu, S. S.; Mauskopf, P. D.; Murphy, J. A.; O'Sullivan, C.; Piccirillo, L.; Timbie, P. T.; Tucker, G. S.; Wandelt, B. D.

    2006-12-01

    We report on the status of the Millimeter-Wave Bolometric Interferometer (MBI), an instrument designed for polarization measurements of the cosmic microwave background (CMB). MBI combines the differencing capabilities of an interferometer with the high sensitivity of bolometers. The design of the ground-based four-channel version of the instrument with 7-degree-FOV corrugated horns (MBI-4) and first measurements results are discussed. Corrugated horn antennas with low sidelobes and nearly symmetric beam patterns minimize spurious instrumental polarization. The MBI-4 optical band is limited by filters with a central frequency of 90 GHz. The antenna separation is chosen so the instrument is sensitive over the multipole range l=150-270. In MBI-4, the signals from antennas are combined with a quasi-optical Fizeau beam combiner and interference fringes are detected by an array of spider-web bolometers with NTD germanium thermistors. In order to separate the visibility signals from the total power detected by each bolometer, the phase of the signal from each antenna is modulated by a ferrite-based waveguide phase shifter. First observations will be from the Pine Bluff Observatory outside Madison, WI. The project is supported by NASA.

  10. The millimeter-wave bolometric interferometer

    NASA Astrophysics Data System (ADS)

    Korotkov, Andrei L.; Kim, Jaiseung; Tucker, Gregory S.; Gault, Amanda; Hyland, Peter; Malu, Siddharth; Timbie, Peter T.; Bunn, Emory F.; Bierman, Evan; Keating, Brian; Murphy, Anthony; O'Sullivan, Créidhe; Ade, Peter A. R.; Calderon, Carolina; Piccirillo, Lucio

    2006-06-01

    The Millimeter-Wave Bolometric Interferometer (MBI) is designed for sensitive measurements of the polarization of the cosmic microwave background (CMB). MBI combines the differencing capabilities of an interferometer with the high sensitivity of bolometers at millimeter wavelengths. It views the sky directly through corrugated horn antennas with low sidelobes and nearly symmetric beam patterns to avoid spurious instrumental polarization from reflective optics. The design of the first version of the instrument with four 7-degree-FOV corrugated horns (MBI-4) is discussed. The MBI-4 optical band is defined by filters with a central frequency of 90 GHz. The set of baselines determined by the antenna separation makes the instrument sensitive to CMB polarization fluctuations over the multipole range l=150-270. In MBI-4, the signals from antennas are combined with a Fizeau beam combiner and interference fringes are detected by an array of spider-web bolometers with NTD germanium thermistors. In order to separate the visibility signals from the total power detected by each bolometer, the phase of the signal from each antenna is modulated by a ferrite-based waveguide phase shifter. Observations are planned from the Pine Bluff Observatory outside Madison, WI.

  11. Quadrature density interferometer with optical fiber

    NASA Astrophysics Data System (ADS)

    Kim, M.-S.; Bellan, P. M.

    2000-10-01

    A He-Ne interferometer is being constructed and will be used to measure the plasma density in the Caltech solar prominence simulation experiment. The design is based on the Buchenauer-Jacobson [1] quadrature concept but uses retroreflectors to have a double-pass optical path and also an optical fiber in order to have flexibility in the optical path. A 632.8 nm polarized He-Ne laser beam is split and travels along two separate paths (reference and scene beams). The scene beam is guided by a one meter single-mode phase-maintaining fiber before entering the vacuum chamber. The beam will pass through the plasma, be reflected from a retroreflector mounted inside the vacuum chamber and then travel back to re-enter the fiber. The flexibility of the fiber permits translations or rotations of the signal path so that different portions of the plasma can be measured. We have successfully demonstrated the operation of the fiber-coupled quadrature interferometer on the benchtop and will be installing it shortly on the solar prominence equipment. [1]: C.J. Buchenauer and A.R. Jacobson, Rev. Sci. Instrum. 48, 769 (1997).

  12. Integrated optic Michelson interferometer for sensors application

    NASA Astrophysics Data System (ADS)

    Mar?, P.; Gorecki, C.; Nieradko, ?.

    2008-04-01

    Integrated optic interferometric systems have been developed since many years and most of them are connected with telecommunication. In case of our group research profile we are focused on integrated optic sensors technology. One of possible application is the atomic force microscope (AFM). In the paper is presented the new concept that combines the AFM with the integrated optic interferometer. In the AFM system a cantilever movement control is the most important. The main goal of the project is improving sensitivity of the AFM by means integrated optic Michelson interferometer (IOMI). The optical waveguide structure was fabricated by surface micromachining technique, based on sandwiched silicon oxide and silicon oxynitride layers. The standard IOMI consist of two Y-junction in which one arm is playing the role of reference arm and other the measuring arm. Such configuration requires four fiber-to-chip connections. Thus, in our configuration, the integrated optic loop mirror in reference arm is fabricated. In the signal arm of our chip standard Grin lens to form an illumination cantilever optical beam is used. In the paper some theoretical descriptions and preliminary results are presented. The possibility of applying the heterodyned detection scheme in a IOMI as a step with sensitivity improvement is described, also. As the project is in progress, the paper is focused in the fabrication of the optical sensor. Next step will be optimization of the electronic part to improve the z-axis sensitivity of the AFM.

  13. Adaptive DFT-Based Interferometer Fringe Tracking

    NASA Astrophysics Data System (ADS)

    Wilson, Edward; Pedretti, Ettore; Bregman, Jesse; Mah, Robert W.; Traub, Wesley A.

    An automatic interferometer fringe tracking system has been developed, implemented, and tested at the Infrared Optical Telescope Array (IOTA) Observatory at Mount Hopkins, Arizona. The system can minimize the optical path differences (OPDs) for all three baselines of the Michelson stellar interferometer at IOTA. Based on sliding window discrete Fourier-transform (DFT) calculations that were optimized for computational efficiency and robustness to atmospheric disturbances, the algorithm has also been tested extensively on offline data. Implemented in ANSI C on the 266 MHz PowerPC processor running the VxWorks real-time operating system, the algorithm runs in approximately 2.0 milliseconds per scan (including all three interferograms), using the science camera and piezo scanners to measure and correct the OPDs. The adaptive DFT-based tracking algorithm should be applicable to other systems where there is a need to detect or track a signal with an approximately constant-frequency carrier pulse. One example of such an application might be to the field of thin-film measurement by ellipsometry, using a broadband light source and a Fourier-transform spectrometer to detect the resulting fringe patterns.

  14. Dual-domain lateral shearing interferometer

    DOEpatents

    Naulleau, Patrick P.; Goldberg, Kenneth Alan

    2004-03-16

    The phase-shifting point diffraction interferometer (PS/PDI) was developed to address the problem of at-wavelength metrology of extreme ultraviolet (EUV) optical systems. Although extremely accurate, the fact that the PS/PDI is limited to use with coherent EUV sources, such as undulator radiation, is a drawback for its widespread use. An alternative to the PS/PDI, with relaxed coherence requirements, is lateral shearing interferometry (LSI). The use of a cross-grating, carrier-frequency configuration to characterize a large-field 4.times.-reduction EUV lithography optic is demonstrated. The results obtained are directly compared with PS/PDI measurements. A defocused implementation of the lateral shearing interferometer in which an image-plane filter allows both phase-shifting and Fourier wavefront recovery. The two wavefront recovery methods can be combined in a dual-domain technique providing suppression of noise added by self-interference of high-frequency components in the test-optic wavefront.

  15. Contrast optimization in a high-precision interferometer

    NASA Astrophysics Data System (ADS)

    Simonova, Galina V.

    2004-12-01

    The accuracy of a high-precision interferometric experiment depends both on instrument errors and errors connected to interferograms processing. Both types of errors can be minimized by an optimum adjustment of the interferometer functions. The paper addresses the issue of the fringe pattern contrast optimization via the application of the electrochromic coating on the reference surface of the interferometer.

  16. Simulation of Fabry-Perot cavities in a Michelson interferometer

    Microsoft Academic Search

    Lina Aguilar-Lobo; Claudia Moreno; Guillermo Garcia-Torales

    2009-01-01

    The Laser Interferometer Gravitational-Wave Observatory (LIGO) has designed to detect Gravitational Waves (GW); its system of detection is based on the Michelson interferometer configuration. When a GW hit on it, the optical elements are disturbed inducing a change in the optical path difference (OPD). The arms length in the detector should be of hundreds of kilometers, due to the small

  17. Method of single-fiber multimode interferometer speckle signal processing

    Microsoft Academic Search

    Yuri N. Kulchin; Oleg B. Vitrik; Oleg V. Kirichenko; Oleg T. Kamenev; Yuri S. Petrov; Oleg G. Maksayev

    1996-01-01

    A method of correlation processing of speckle-signals formed by multimode interferometer is theoretically and experimentally investigated. The method permits to transform modulation of a speckle-pattern to optical or electrical signal, which linear depends on correlation coefficient of reference and current speckle patterns. The functional dependence of correlation coefficient from value of lengthening of interferometer is studied. The results allow to

  18. Interferometer for measurement of absolute refractive index and thickness

    Microsoft Academic Search

    Serguei A. Alexandrov; I. V. Chernyh

    1993-01-01

    The interferometer model for measurement of the absolute refractive index of the optical media with the accuracy of 0.00001 has been developed, manufactured and researched. The sample for test to be manufactured as the flat parallel plate. The interferometer gives possibility to defined sample geometrical thickness with accuracy 0.0002 mm simultaneously with index measurement. The range of index and thickness

  19. Numerical simulation and experimental verification of extended source interferometer

    NASA Astrophysics Data System (ADS)

    Hou, Yinlong; Li, Lin; Wang, Shanshan; Wang, Xiao; Zang, Haijun; Zhu, Qiudong

    2013-12-01

    Extended source interferometer, compared with the classical point source interferometer, can suppress coherent noise of environment and system, decrease dust scattering effects and reduce high-frequency error of reference surface. Numerical simulation and experimental verification of extended source interferometer are discussed in this paper. In order to provide guidance for the experiment, the modeling of the extended source interferometer is realized by using optical design software Zemax. Matlab codes are programmed to rectify the field parameters of the optical system automatically and get a series of interferometric data conveniently. The communication technique of DDE (Dynamic Data Exchange) was used to connect Zemax and Matlab. Then the visibility of interference fringes can be calculated through adding the collected interferometric data. Combined with the simulation, the experimental platform of the extended source interferometer was established, which consists of an extended source, interference cavity and image collection system. The decrease of high-frequency error of reference surface and coherent noise of the environment is verified. The relation between the spatial coherence and the size, shape, intensity distribution of the extended source is also verified through the analysis of the visibility of interference fringes. The simulation result is in line with the result given by real extended source interferometer. Simulation result shows that the model can simulate the actual optical interference of the extended source interferometer quite well. Therefore, the simulation platform can be used to guide the experiment of interferometer which is based on various extended sources.

  20. Surface figure measurements of radio telescopes with a shearing interferometer

    Microsoft Academic Search

    E. Serabyn; T. G. Phillips; C. R. Masson

    1991-01-01

    A new technique for determining the surface figure of large submillimeter wavelength telescopes is presented, which is based on measuring the telescope's focal plane diffraction pattern with a shearing interferometer. In addition to the instrumental theory, results obtained using such an interferometer on the 10.4-m diam telescope of the Caltech Submillimeter Observatory are discussed. Using wavelengths near 1 mm, a

  1. Imaging interferometer using dual broadband quantum well infrared photodetectors

    NASA Technical Reports Server (NTRS)

    Reininger, F.; Gunapala, S.; Bandara, S.; Grimm, M.; Johnson, D.; Peters, D.; Leland, S.; Liu, J.; Mumolo, J.; Rafol, D.; Thomas, I.; Ting, D.; Wilson, D.

    2002-01-01

    The Jet Propulsion Laboratory is developing a new imaging interferometer that has double the efficiency of conventional interferometers and only a fraction of the mass and volume. The project is being funded as part of the Defense Advanced Research Projects Agency (DARPA) Photonic Wavelength And Spatial Signal Processing program (PWASSSP).

  2. Mission analysis for the Laser Interferometer Space Antenna (LISA) mission

    Microsoft Academic Search

    F. Hechler; W. M. Folkner

    2003-01-01

    The interplanetary orbits of three pairs of spacecraft, forming three laser interferometers, are designed such that their separations, i.e. the lengths of the interferometer arms, remain nearly constant. Each spacecraft pair is located near the vertex of a rotating equilateral triangle formed by the individual orbits of the spacecraft about the Sun. Feasible spacecraft masses are computed for a scenario

  3. Transmission line based microwave interferometers for plasma density measurements

    Microsoft Academic Search

    C. H. Hsieh; J. H. Wang; C. Lin; K. C. Leou

    2010-01-01

    Summary form only given. Here we report the development of microwave interferometers based on transmission-line (TL) structures for monitoring of plasma density for applications in process monitoring or realtime feedback control of plasma based semiconductor fabrication tools, such plasma etchers or PECVDs. The principle of this technique is the same as the conventional microwave interferometers except that the sensing microwave

  4. Measurement of polarization with the Degree Angular Scale Interferometer

    E-print Network

    Cai, Long

    Measurement of polarization with the Degree Angular Scale Interferometer E. M. Leitch*, J. M. Kovac ........................................................................................................................................................................................................................... Measurements of the cosmic microwave background (CMB) radiation can reveal with remarkable precision Interferometer (DASI), an array of radio telescopes, which for the past two years has conducted polarization

  5. A quantum scattering interferometer Russell A. Hart1

    E-print Network

    Gibble, Kurt

    LETTERS A quantum scattering interferometer Russell A. Hart1 , Xinye Xu1 {, Ronald Legere1 { & Kurt shifts of individual atoms are detected using a novel atom interferometer. By per- forming an atomic pass through a microwave (clock) cavity, which puts the atoms in cloud 2 in a coherent superposition

  6. Measuring nanomechanical motion with a microwave cavity interferometer

    E-print Network

    Loss, Daniel

    ARTICLES Measuring nanomechanical motion with a microwave cavity interferometer C. A. REGAL*, J. D of a nanomechanical beam using a superconducting transmission-line microwave cavity. We realize excellent mechanical displacement detector that, in principle, is capable of reaching the SQL is an optical cavity interferometer

  7. Reflectors for a Microwave Fabry-Perot Interferometer

    Microsoft Academic Search

    W. Culshaw

    1959-01-01

    The advantages of microwave interferometers for wavelength and other measurements at millimeter wavelengths are indicated, and a microwave Fabry-Perot interferometer discussed in detail. Analogous to the cavity resonator, this requires reflectors of high reflectivity, small absorption, and adequate size. Stacked dielectric plates, and stacked planar or rod gratings are shown to be suitable forms of reflectors, and equations for the

  8. Calculations and measurements on an X-band microwave interferometer

    Microsoft Academic Search

    A. J. Postma; J. C. Terlouw

    1963-01-01

    A microwave interferometer which is suitable for the measurement of the electron density in the positive column of a gas discharge is described. The discharge tube is placed in the waveguide structure. The construction of the interferometer is such that reflexions of the e.m. signal on the plasma boundary are very small. The propagation constant was solved numerically from the

  9. Modes in a maser interferometer with curved and tilted mirrors

    Microsoft Academic Search

    A. G. Fox; Tingye Li

    1963-01-01

    Fabry-Perot interferometers have played an important role in the conception and realization of optical masers. The authors have previously made a study of the idealized interferometer. In this paper they present some results of a continued study of the effects of certain simple forms of aberration. The first is represented by tilted plane mirrors and the second by curved mirrors.

  10. CONTROL TECHNOLOGY READINESS FOR SPACEBORNE OPTICAL INTERFEROMETER MISSIONS

    Microsoft Academic Search

    Gregory W. NEAT; Alex ABRAMOVICI; James W. MELODY; Robert J. CALVET; Noble M. NERHEIM; John F. O'BRIEN

    This paper describes the Micro-Precision Interferometer (MPI) testbed and its ma- jor achievements to date related to mitigating risk for future spaceborne optical inter- ferometer missions. The MPI testbed is a ground-based hardware model of a future spaceborne interferometer. The three primary objectives of the testbed are to: (1) demonstrate the 10 nm positional stability requirement in the ambient lab

  11. Length Sensing and Control in the Virgo Gravitational Wave Interferometer

    Microsoft Academic Search

    Fausto Acernese; P. Amico; M. Al-Shourbagy; S. Aoudia; S. Avinok; D. Babusci; G. Ballardin; R. Barille; Fabrizio Barone; L. Barsotti; M. A. Bizouardyy; F. Beauville; M. A. Bizouard; C. Bradaschia; F. Bondu; L. Bosi; S. Braccini; A. Brillet; V. Brisson; L. Brocco; D. Buskulic; E. Calloni; E. Campagna; F. Cavalier; R. Cavalieri; G. Cella; E. Chassande-Mottin; C. Corda; A.-C. Clapson; F. Cleva; J.-P. Coulon; Elena Cuoco; V. Dattilo; M. Davier; Rosario De Rosa; L. Di Fiore; A. Di Virgilio; B. Dujardin; Antonio Eleuteri; D. Enard; I. Ferrante; F. Fidecaro; I. Fiori; R. Flaminio; J.-D. Fournier; S. Frasca; F. Frasconi; A. Freise; L. Gammaitoni; A. Gennai; A. Giazotto; G. Giordano; L. Giordano; R. Gouaty; D. Grosjean; G. Guidi; S. Hebri; H. Heitmann; P. Hello; L. Holloway; S. Kreckelbergh; Paolo La Penna; Vincent Loriette; M. Loupias; Giovanni Losurdo; J.-M. Mackowski; E. Majorana; C. N. Man; Marco Mantovani; Fabio Marchesoni; F. Marion; J. Marque; F. Martelli; A. Masserot; Massimo Mazzoni; Leopoldo Milano; C. Moins; J. Moreau; N. Morgado; B. Mours; A. Pai; C. Palomba; F. Paoletti; S. Pardi; A. Pasqualetti; R. Passaquieti; D. Passuello; B. Perniola; F. Piergiovanni; L. Pinard; R. Poggiani; M. Punturo; P. Puppo; K. Qipiani; P. Rapagnani; V. Reita; A. Remillieux; F. Ricci; I. Ricciardi; P. Ruggi; Giovanni Russo; S. Solimeno; A. Spallicci; Ruggero Stanga; R. Taddei; D. Tombolato; Mauro Tonelli; Alessandra Toncelli; E. Tournefier; F. Travasso; G. Vajente; D. Verkindt; F. Vetrano; Andrea Vicerè; J.-Y. Vinet; Helios Vocca; M. Yvert; Z. Zhang

    2006-01-01

    The gravitational wave detector Virgo is presently being commissioned. A significant part of last year was spent in setting up the cavity length control system. This work was carried out with steps of increasing complexity: locking a simple Fabry- Perot cavity, then a Michelson interferometer with Fabry-Perot cavities in both arms, and finally recycling the light beam into the interferometer.

  12. Studies on arrays of Josephson tunnel junction interferometers

    Microsoft Academic Search

    Ronald F. Broom; T. O. Mohr

    1978-01-01

    Josephson-junction interferometers have previously been proposed as memory devices in which information is stored as a single flux quantum, (SFQ). To investigate the feasibility of making large arrays of SFQ cells suitable for the memory of a cryogenic computer, arrays containing 80 interferometers have been made and measured. The prime objective was to determine the distribution of the dc Josephson

  13. Two-Dimensional X-Ray Grating Interferometer

    SciTech Connect

    Zanette, Irene [European Synchrotron Radiation Facility, Grenoble (France); Weitkamp, Timm [European Synchrotron Radiation Facility, Grenoble (France); Synchrotron Soleil, Gif-sur-Yvette (France); Donath, Tilman; Rutishauser, Simon; David, Christian [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, Villigen (Switzerland)

    2010-12-10

    We report on the design and experimental realization of a 2D x-ray grating interferometer. We describe how this interferometer has been practically implemented, discuss its performance, and present multidirectional scattering (dark-field) maps and quantitative phase images that have been retrieved using this device.

  14. Australian Weather Watch Radar Home Page

    NSDL National Science Digital Library

    The Commonwealth Bureau of Meteorology's Weather Watch Radar website provides up-to-date radar images of the locations of rain in Australia in relation to local features such as coast lines. The newly developed Loops provide four consecutive radar images so that users can view how the weather has been changing in the last forty to fifty minutes. The website provides radar images of past cyclone events as well as updates on severe weather throughout Australia. Those interested in radar systems can discover how the weather radars work and how to interpret the maps. [RME

  15. Dispersion interferometer using modulation amplitudes on LHD (invited)

    SciTech Connect

    Akiyama, T., E-mail: takiyama@lhd.nifs.ac.jp; Yasuhara, R.; Kawahata, K. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki-shi, Gifu 509-5292 (Japan); Okajima, S.; Nakayama, K. [Chubu University, Matsumoto-cho, Kasugai-shi, Aichi 487-8501 (Japan)

    2014-11-15

    Since a dispersion interferometer is insensitive to mechanical vibrations, a vibration compensation system is not necessary. The CO{sub 2} laser dispersion interferometer with phase modulations on the Large Helical Device utilizes the new phase extraction method which uses modulation amplitudes and can improve a disadvantage of the original dispersion interferometer: measurement errors caused by variations of detected intensities. The phase variation within ±2 × 10{sup 17} m{sup ?3} is obtained without vibration compensation system. The measured line averaged electron density with the dispersion interferometer shows good agreement with that with the existing far infrared laser interferometer. Fringe jump errors in high density ranging up to 1.5 × 10{sup 20} m{sup ?3} can be overcome by a sufficient sampling rate of about 100 kHz.

  16. Multichannel microwave interferometer for the levitated dipole experiment

    SciTech Connect

    Boxer, Alexander C. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Garnier, Darren T.; Mauel, Michael E. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027 (United States)

    2009-04-15

    A four-channel microwave interferometer (center frequency: 60 GHz) has been constructed to measure plasma density profiles in the levitated dipole experiment (LDX). The LDX interferometer has a unique design owing to the unique geometry of LDX. The main design features of the interferometer are: (1) the transmitted beam traverses the plasma entirely in O-mode; (2) the interferometer is a heterodyne system employing two free-running oscillators; (3) four signals of data are received from just on transmitted beam; (4) phase shifts are detected in quadrature. Calibration tests demonstrate that the interferometer measures phase shifts with an uncertainty of approximately 5 deg. Plasma densities in LDX corresponding to phase shifts of up to 5{pi} are routinely and successfully measured.

  17. Multichannel microwave interferometer for the levitated dipole experiment.

    PubMed

    Boxer, Alexander C; Garnier, Darren T; Mauel, Michael E

    2009-04-01

    A four-channel microwave interferometer (center frequency: 60 GHz) has been constructed to measure plasma density profiles in the levitated dipole experiment (LDX). The LDX interferometer has a unique design owing to the unique geometry of LDX. The main design features of the interferometer are: (1) the transmitted beam traverses the plasma entirely in O-mode; (2) the interferometer is a heterodyne system employing two free-running oscillators; (3) four signals of data are received from just on transmitted beam; (4) phase shifts are detected in quadrature. Calibration tests demonstrate that the interferometer measures phase shifts with an uncertainty of approximately 5 degrees . Plasma densities in LDX corresponding to phase shifts of up to 5pi are routinely and successfully measured. PMID:19405655

  18. Design of a 24-in. phase shifting interferometer

    NASA Astrophysics Data System (ADS)

    Ai, Chiayu; Knowlden, Robert E.; Lamb, Joseph A.

    1996-11-01

    WYKO Corporation is designing and building 24' (61 cm) aperture phase shifting interferometers to aid in the manufacture and qualification of optics for the NIF (U.S. National Ignition Facility). The first interferometer is scheduled for delivery in early 1997. The 24' systems will be the largest commercially available phase shifting interferometers, and will use a megapixel CCD camera to give high lateral resolution. Some of the NIF optics will be tested at Brewster's angle, and that condition places unusual design requirements on the interferometer. The main effect of testing a planar optical element in transmission at Brewster's angle is that there is a large separation between areas of the element and the return flat, so that optical propagation effects become important. We describe our design of a large aperture phase shifting interferometer, and how it will be used to test the NIF optics.

  19. Wavefront testing of pinhole based on point diffraction interferometer

    NASA Astrophysics Data System (ADS)

    Jia, Xin; Xing, Tingwen; Xu, Jiajun; Lin, Wumei; Liao, Zhijie

    2013-04-01

    To overcome the accuracy limitation due to the aberration of reference wavefront in the interferometer testing, the point diffraction interferometer (PDI) uses the pinhole to create an ideal diffraction sphere wavefront as the reference wavefront. Because the perfect pinhole is hard to manufacture, then the imperfect pinhole will cause the wavefront errors which will influence the test accuracy. In this paper we use the absolute testing method to test the wave front of the pinhole. Then the testing accuracy of point diffraction interferometer can be improved by subtracting the error of the pinhole. In this paper a Phase-shifting point diffraction interferometer system is designed to testing the pinhole. We use three pinholes to test each other. According the algorithm of the absolute testing method, we can calculate the wavefront error of the pinhole. Then the testing accuracy of point diffraction interferometer can be improved by subtracting the error of the pinhole.

  20. Solar Confocal interferometers for Sub-Picometer-Resolution Spectral Filters

    NASA Technical Reports Server (NTRS)

    Gary, G. Allen; Pietraszewski, Chris; West, Edward A.; Dines. Terence C.

    2007-01-01

    The confocal Fabry-Perot interferometer allows sub-picometer spectral resolution of Fraunhofer line profiles. Such high spectral resolution is needed to keep pace with the higher spatial resolution of the new set of large-aperture solar telescopes. The line-of-sight spatial resolution derived for line profile inversions would then track the improvements of the transverse spatial scale provided by the larger apertures. In particular, profile inversion allows improved velocity and magnetic field gradients to be determined independent of multiple line analysis using different energy levels and ions. The confocal interferometer's unique properties allow a simultaneous increase in both etendue and spectral power. The higher throughput for the interferometer provides significant decrease in the aperture, which is important in spaceflight considerations. We have constructed and tested two confocal interferometers. A slow-response thermal-controlled interferometer provides a stable system for laboratory investigation, while a piezoelectric interferometer provides a rapid response for solar observations. In this paper we provide design parameters, show construction details, and report on the laboratory test for these interferometers. The field of view versus aperture for confocal interferometers is compared with other types of spectral imaging filters. We propose a multiple etalon system for observing with these units using existing planar interferometers as pre-filters. The radiometry for these tests established that high spectral resolution profiles can be obtained with imaging confocal interferometers. These sub-picometer spectral data of the photosphere in both the visible and near-infrared can provide important height variation information. However, at the diffraction-limited spatial resolution of the telescope, the spectral data is photon starved due to the decreased spectral passband.

  1. Processing System and Algorithms for the TanDEM-X Mission

    Microsoft Academic Search

    Michael Eineder; Thomas Fritz; Helko Breit; Nico Adam; Nestor Yague-Martinez; Marie Lachaise; Ramon Brcic

    2009-01-01

    In 2009, the German radar satellite TerraSAR-X will be supplemented with the TanDEM-X satellite to form the first bi-static single pass interferometer in space. TanDEM-X will fly close to TerraSAR-X in a controlled helix configuration for 3 years to jointly acquire interferometric SAR data in bistatic mode. The primary TanDEM-X mission goal is to generate a global Digital Elevation Model

  2. SUBMITTED TO IEE PROCEEDINGS RADAR, SONAR & NAVIGATION 1 Region-Enhanced Passive Radar Imaging

    E-print Network

    Willsky, Alan S.

    SUBMITTED TO IEE PROCEEDINGS RADAR, SONAR & NAVIGATION 1 Region-Enhanced Passive Radar Imaging M;SUBMITTED TO IEE PROCEEDINGS RADAR, SONAR & NAVIGATION 2 Abstract We adapt and apply a recently-developed region-enhanced synthetic aperture radar (SAR) image reconstruction technique to the problem of passive

  3. Space Plasma Exploration by Active Radar (SPEAR): an overview of a future radar facility

    E-print Network

    Paris-Sud XI, Université de

    Space Plasma Exploration by Active Radar (SPEAR): an overview of a future radar facility D. M is a new polar cap HF radar facility which is to be deployed on Svalbard. The principal capabilities of SPEAR will include the generation of arti®cial plasma irregularities, operation as an `all-sky' HF radar

  4. Multifrequency and multipolarization radar scatterometry of sand dunes and comparison with spaceborne and airborne radar images

    Microsoft Academic Search

    Ronald Blom; Charles Elachi

    1987-01-01

    Understanding the unusual radar scattering characteristics of sand dunes is necessary in the analysis of radar images of aeolian landscapes of the earth and of other planets. In this paper we report on airborne radar scatterometer data of sand dunes, acquired at multiple frequencies and polarizations. Radar backscatter from sand dunes is very sensitive to the imaging geometry. At small

  5. Imaging radar techniques for remote sensing applications.

    NASA Technical Reports Server (NTRS)

    Zelenka, J. S.

    1972-01-01

    The basic concepts of fine-resolution, imaging radar systems are reviewed. Both side-looking and hologram (downward-looking) radars are described and compared. Several examples of microwave imagery obtained with these two types of systems are shown.

  6. Obstacle penetrating dynamic radar imaging system

    DOEpatents

    Romero, Carlos E. (Livermore, CA); Zumstein, James E. (Livermore, CA); Chang, John T. (Danville, CA); Leach, Jr.. Richard R. (Castro Valley, CA)

    2006-12-12

    An obstacle penetrating dynamic radar imaging system for the detection, tracking, and imaging of an individual, animal, or object comprising a multiplicity of low power ultra wideband radar units that produce a set of return radar signals from the individual, animal, or object, and a processing system for said set of return radar signals for detection, tracking, and imaging of the individual, animal, or object. The system provides a radar video system for detecting and tracking an individual, animal, or object by producing a set of return radar signals from the individual, animal, or object with a multiplicity of low power ultra wideband radar units, and processing said set of return radar signals for detecting and tracking of the individual, animal, or object.

  7. A Study of Single Pass Ion Effects at the ALS

    SciTech Connect

    Byrd, J.M.; Thomson, J.; /LBL, Berkeley; Chao, A.W.; Heifets, S.; Minty, M.G.; Seeman, J.T.; Stupakov, G.V.; Zimmermann, F.; /SLAC; Raubenheimer, T.O.; /CERN

    2011-09-13

    We report the results of experiments on a 'fast beam-ion instability' at the Advanced Light Source (ALS). This ion instability, which can arise even when the ions are not trapped over multiple beam passages, will likely be important for many future accelerators. In our experiments, we filled the ALS storage ring with helium gas, raising the pressure approximately two orders of magnitude above the nominal pressure. With gaps in the bunch train large enough to avoid conventional (multi-turn) ion trapping, we observed a factor of 2-3 increase in the vertical beam size along with coherent beam oscillations which increased along the bunch train. Ion trapping has long been recognized as a potential limitation in electron storage rings. The ions, generated by beam-gas collisions, become trapped in the negative potential of the beam and accumulate over multiple beam passages. The trapped ions are then observed to cause a number of deleterious effects such as an increasing beam phase space, a broadening and shifting of the beam transverse oscillation frequencies (tunes), collective beam instabilities, and beam lifetime reductions. All of these effects are of concern for the next generation of accelerators, such as the B-factories or damping rings for future linear colliders, which will store high beam currents with closely spaced bunches and ultra-low beam emittances. One of the standard solutions used to prevent ion trapping is to include a gap in the bunch train which is long compared to the bunch spacing. In this case, the ions are first strongly-focused by the passing electron bunches and then over-focused in the gap. With a sufficiently large gap, the ions can be driven to large amplitudes where they form a diffuse halo and do not affect the beam. In this paper, we describe experiments that study a new regime of transient ion instabilities predicted to arise in future electron storage rings, and linacs with bunch trains. These future rings and linacs, which will be operated with higher beam currents, small transverse beam emittances, and long bunch trains, will use ion clearing gaps to prevent conventional ion trapping. But, while the ion clearing gap may suppress the conventional ion instabilities, it will not suppress a transient beam-ion instability where ions generated and trapped during the passage of a single train lead to a fast instability. While both conventional and transient ion instabilities have the same origin, namely ions produced by the beam, they have different manifestations and, more importantly, the new transient instability can arise even after the conventional ion instability is cured. This new instability is called the 'Fast Beam-Ion Instability' (FBII). In many future rings, the FBII is predicted to have very fast growth rates, much faster than the damping rates of existing and proposed transverse feedback systems, and thus is a potential limitation. To study the FBII, we performed experiments at the ALS, a 1.5 GeV electron storage ring. At the nominal ALS pressure of about 0.24 nTorr, the FBII is not evident. To study the instability, we intentionally added helium gas to the storage-ring vacuum system until the residual gas pressure was increased about 80 nTorr. This brought the predicted growth rate of the instability at least an order of magnitude above the growth rate of conventional multibunch instabilities driven by the RF cavities and above the damping rate of the transverse feedback system (TFB) in the ALS and, thereby, established conditions very similar to those in a future storage ring. We then filled the ring with a relatively short train of bunches, suppressing conventional ion instabilities. In the following, we will first briefly describe This paper describes the experiment and results in more detail.

  8. Single pass image warping method with anisotropic filter

    NASA Astrophysics Data System (ADS)

    Lachine, Vladimir; Smith, Gregory; Lee, Louie

    2013-09-01

    Conventional image capture and display devices are prone to various form of optical artifacts. These artifacts are inherent to the non-ideal behavior of the various optical elements such as sensors, displays, lens, prisms, mirrors, light sources. These optical distortions may be corrected digitally by image warping technology. Image warping may be defined as a process of dynamically resampling a regularly spaced input image to produce a nonregular spacing output image. In this paper, one-pass algorithm for digital image warping is presented. It is based on anisotropic circularly symmetric antialiasing filtering over elliptical or rectangular footprint. It is shown that developed design provides flexibility and better image quality than known two-pass methods. The proposed algorithm has been embedded into a few display processors for optical distortion corrections both at image acquisition and displaying sides.

  9. Hanford single-pass reactor fuel storage basin demolition.

    PubMed

    Armstrong, Jason A

    2003-02-01

    The Environmental Restoration Contractor at the Hanford Site is tasked with removing auxiliary reactor structures and leaving the remaining concrete structure surrounding each reactor core. This is referred to as Interim Safe Storage. Part of placing the F Reactor into Interim Safe Storage is the demolition of the fuel storage basin, which was deactivated in 1970 by placing debris material into the basin prior to back filling with soil. Besides the debris material (wooden floor decking, handrails, and monorail pieces), the fuel storage basin contents included the possibility of spent nuclear fuel, fuel buckets, fuel spacers, process tubes, and tongs. Demolition of the fuel storage basin offered many unique radiological control challenges and innovative approaches to demolition. This paper describes how the total effective dose equivalent and contamination were controlled, how the use of a remote operated excavator was employed to remove high-dose-rate material, and how wireless technology was used to monitor changing radiological conditions. PMID:12564339

  10. Radar Mosaic of Africa

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This is an image of equatorial Africa, centered on the equator at longitude 15degrees east. This image is a mosaic of almost 4,000 separate images obtained in 1996 by the L-band imaging radar onboard the Japanese Earth Resources Satellite. Using radar to penetrate the persistent clouds prevalent in tropical forests, the Japanese Earth Resources Satellite was able for the first time to image at high resolution this continental scale region during single flooding seasons. The area shown covers about 7.4 million square kilometers (2.8 million square miles) of land surface, spans more than 5,000 kilometers(3,100 miles) east and west and some 2,000 kilometers (1,240 miles) north and south. North is up in this image. At the full resolution of the mosaic (100 meters or 330 feet), this image is more than 500 megabytes in size, and was processed from imagery totaling more than 60 gigabytes.

    Central Africa was imaged twice in 1996, once between January and March, which is the major low-flood season in the Congo Basin, and once between October and November, which is the major high-flood season in the Congo Basin. The red color corresponds to the data from the low-flood season, the green to the high-flood season, and the blue to the 'texture' of the low-flood data. The forests appear green as a result, the flooded and palm forests, as well as urban areas, appear yellow, the ocean and lakes appear black, and savanna areas appear blue, black or green, depending on the savanna type, surface topography and other factors. The areas of the image that are black and white were mapped only between January and March 1996. In these areas, the black areas are savanna or open water, the gray are forests, and the white areas are flooded forests or urban areas. The Congo River dominates the middle of the image, where the nearby forests that are periodically flooded by the Congo and its tributaries stand out as yellow. The Nile River flows north from Lake Victoria in the middle right of the color portion of the mosaic.

    This image is one of the products resulting from the Global Rain Forest Mapping project, a joint project between the National Space Development Agency of Japan, the Space Applications Institute of the Joint Research Centre of the European Commission, NASA's Jet Propulsion Laboratory and an international team of scientists. The goal of the Global Rain Forest Mapping mission is to map with the Japanese Earth Resources Satellite the world's tropical rain forests. The Japanese satellite was launched in 1992 by the National Space Development Agency of Japan and the Japanese Ministry of International Trade and Industry, with support from the Remote Sensing Technology Center of Japan.

  11. Radar reflection off extensive air showers

    E-print Network

    Stasielak, J; Bertaina, M; Blümer, J; Chiavassa, A; Engel, R; Haungs, A; Huege, T; Kampert, K -H; Klages, H; Kleifges, M; Krömer, O; Ludwig, M; Mathys, S; Neunteufel, P; Pekala, J; Rautenberg, J; Riegel, M; Roth, M; Salamida, F; Schieler, H; Šmída, R; Unger, M; Weber, M; Werner, F; Wilczy?ski, H; Wochele, J

    2012-01-01

    We investigate the possibility of detecting extensive air showers by the radar technique. Considering a bistatic radar system and different shower geometries, we simulate reflection of radio waves off the static plasma produced by the shower in the air. Using the Thomson cross-section for radio wave reflection, we obtain the time evolution of the signal received by the antennas. The frequency upshift of the radar echo and the power received are studied to verify the feasibility of the radar detection technique.

  12. Bird-aircraft strike avoidance radar

    Microsoft Academic Search

    Ning Huansheng; Chen Weishi; Mao Xia; Li Jing

    2010-01-01

    Avian radar system has been developed for bird-aircraft strike hazard avoidance. Two representative systems, which are countrywide and airport-based avian radar systems, are surveyed to summarize the state-of-the-art in this research field. Avian radar experimental system built by Beihang University is introduced in detail, including system architecture, performance analysis, and processing algorithm for bird target detection and tracking. This radar

  13. Radar Images of the Earth: Volcanoes

    NSDL National Science Digital Library

    This site features links to thirty-five NASA radar images of the world's volcanoes, including brief descriptions of the respective processes and settings involved. The images were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radar illuminates Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions.

  14. Bistatic synthetic aperture radar

    NASA Astrophysics Data System (ADS)

    Yates, Gillian

    Synthetic aperture radar (SAR) allows all-weather, day and night, surface surveillance and has the ability to detect, classify and geolocate objects at long stand-off ranges. Bistatic SAR, where the transmitter and the receiver are on separate platforms, is seen as a potential means of countering the vulnerability of conventional monostatic SAR to electronic countermeasures, particularly directional jamming, and avoiding physical attack of the imaging platform. As the receiving platform can be totally passive, it does not advertise its position by RF emissions. The transmitter is not susceptible to jamming and can, for example, operate at long stand-off ranges to reduce its vulnerability to physical attack. This thesis examines some of the complications involved in producing high-resolution bistatic SAR imagery. The effect of bistatic operation on resolution is examined from a theoretical viewpoint and analytical expressions for resolution are developed. These expressions are verified by simulation work using a simple 'point by point' processor. This work is extended to look at using modern practical processing engines for bistatic geometries. Adaptations of the polar format algorithm and range migration algorithm are considered. The principal achievement of this work is a fully airborne demonstration of bistatic SAR. The route taken in reaching this is given, along with some results. The bistatic SAR imagery is analysed and compared to the monostatic imagery collected at the same time. Demonstrating high-resolution bistatic SAR imagery using two airborne platforms represents what I believe to be a European first and is likely to be the first time that this has been achieved outside the US (the UK has very little insight into US work on this topic). Bistatic target characteristics are examined through the use of simulations. This also compares bistatic imagery with monostatic and gives further insight into the utility of bistatic SAR.

  15. High-performance birefringent imaging interferometer

    NASA Astrophysics Data System (ADS)

    Miller, Peter J.

    2000-03-01

    A high-performance birefringent imaging optical spectrometer (BIOS) based on liquid crystal elements is designed, built, and characterized. The result is a remarkably compact and simple system for spectral imaging of 2D scenes, with high throughput (85%), no moving parts, and perfect spatial registration between images. Key results include resolution of 4 nm shifts and demonstration of near diffraction-limited image quality. One special benefit is that the interferometer has a setting at which all wavelengths are transmitted without loss; this `white light' setting is of practical benefit in focusing and other sample handling steps. The signal-to-noise of interferometric systems is derived theoretically and compared against filters-based instruments for various source spectra. Based on this analysis and the demonstrated performance of the BIOS system, it appears well-suited to applications such as discriminating between multiple fluorescent probes.

  16. Coherent Thermoelectric Effects in Mesoscopic Andreev Interferometers

    E-print Network

    Ph. Jacquod; R. S. Whitney

    2009-10-15

    We investigate thermoelectric transport through Andreev interferometers. We show that the ratio of the thermal and the charge conductance exhibits large oscillations with the phase difference $\\phi$ between the two superconducting contacts, and that the Wiedemann-Franz law holds only when $\\phi=\\pi$. A large average thermopower furthermore emerges whenever there is an asymmetry in the dwell times to reach the superconducting contacts. When this is the case, the thermopower is odd in $\\phi$. In contrast, when the average times to reach either superconducting contact are the same, the average thermopower is zero, however mesoscopic effects (analogous to universal conductance fluctuations) lead to a sample-dependent thermopower which is systematically even in $\\phi$.

  17. VINCI: the VLT Interferometer commissioning instrument

    NASA Astrophysics Data System (ADS)

    Kervella, Pierre; Coudé du Foresto, Vincent; Glindemann, Andreas; Hofmann, Reiner

    2000-07-01

    The Very Large Telescope Interferometer (VLTI) is a complex system, made of a large number of separated elements. To prepare an early successful operation, it will require a period of extensive testing and verification to ensure that the many devices involved work properly together, and can produce meaningful data. This paper describes the concept chosen for the VLTI commissioning instrument, LEONARDO da VINCI, and details its functionalities. It is a fiber based two-way beam combiner, associated with an artificial star and an alignment verification unit. The technical commissioning of the VLTI is foreseen as a stepwise process: fringes will first be obtained with the commissioning instrument in an autonomous mode (no other parts of the VLTI involved); then the VLTI telescopes and optical trains will be tested in autocollimation; finally fringes will be observed on the sky.

  18. An Optical Interferometer with Wavelength Dispersion

    E-print Network

    T. R. Bedding; J. G. Robertson; R. G. Marson

    1994-04-04

    MAPPIT is an optical interferometer installed at the coude focus of the 3.9-m Anglo-Australian Telescope. The instrument combines non-redundant masking with wavelength dispersion and is able to record fringes simultaneously over a wide bandwidth. For typical observations centred near 600 nm, the bandwidth is 55 nm and the spectral resolution is 3 nm. This paper describes the instrument and the data processing methods and presents some results. We find the star sigma Sgr to be a close binary; the system is only partially resolved, with a separation of (11.5 +/- 2) milliarcsec (assuming the components to have equal magnitudes). We also give angular diameter measurements of two red giant stars, alpha Sco and beta Gru. The observations of beta Gru (spectral type M5 III) resolve the star for the first time and give an equivalent uniform-disk diameter of (27 +/- 3) milliarcsec.

  19. The aerospace imaging interferometer ALISEO: further improvements of calibration methods and assessment of interferometer response

    NASA Astrophysics Data System (ADS)

    Barducci, A.; Castagnoli, F.; Guzzi, D.; Marcoionni, P.; Pippi, I.

    2007-10-01

    ALISEO (Aerospace Leap-frog Imaging Stationary Interferometer for Earth Observation) belongs to the stationary interferometers representing a promising architecture for future Earth Observation (EO) sensors due to their simple optical layout. ALISEO has been selected by the Italian Space Agency as the principal payload for a new optical mission based on a micro-satellite (MIOsat). Payloads planned for MIOsat are an extensible telescope, a high-resolution panchromatic camera, a Mach-Zehnder MEMS interferometer, and ALISEO. MIOsat is expected to provide a platform with pointing capability for those advanced sensors. ALISEO operates in the common-path Sagnac configuration, and it does not employ any moving part to generate phase delay between the two rays. The sensor acquires the target images modulated by a pattern of autocorrelation functions: a fringe pattern that is fixed with respect to the instrument's field of view. The complete interferogram of each target location is retrieved introducing relative source-observer motion, which allows any image pixels to be observed under different phase delays. Recent laboratory measurements performed with ALISEO are described and discussed in this paper. In order to calibrate the optical path difference (OPD) of raw interferograms, a set of measurements have been carried out using a double planar diffuser system and several coloured He-Ne lasers. Standard reflectance tiles together doped with Holmium and Rare Earths have been used for validating the wavelength calibration of the instrument and proving the reliability of the reflectance retrieving procedure.

  20. VISAR (Velocity Interferometer System for Any Reflector): Line-imaging interferometer

    SciTech Connect

    Hemsing, W.F.; Mathews, A.R.; Warnes, R.H.; Whittemore, G.R.

    1990-01-01

    This paper describes a Velocity Interferometer System for Any Reflector (VISAR) technique that extends velocity measurements from single points to a line. Single-frequency argon laser light was focused through a cylindrical lens to illuminate a line on a surface. The initially stationary, flat surface was accelerated unevenly during the experiment. Motion produced a Doppler-shift of light reflected from the surface that was proportional to the velocity at each point. The Doppler-shifted image of the illuminated line was focused from the surface through a push-pull VISAR interferometer where the light was split into four quadrature-coded images. When the surface accelerated, the Doppler-shift caused the interference for each point on each line image to oscillate sinusoidally. Coherent fiber optic bundles transmitted images from the interferometer to an electronic streak camera for sweeping in time and recording on film. Data reduction combined the images to yield a continuous velocity and displacement history for all points on the surface that reflected sufficient light. The technique was demonstrated in an experiment where most of the surface was rapidly driven to a saddle shape by an exploding foil. Computer graphics were used to display the measured velocity history and to aid visualization of the surface motion. 6 refs., 8 figs.

  1. Scanning ARM Cloud Radar Handbook

    SciTech Connect

    Widener, K; Bharadwaj, N; Johnson, K

    2012-06-18

    The scanning ARM cloud radar (SACR) is a polarimetric Doppler radar consisting of three different radar designs based on operating frequency. These are designated as follows: (1) X-band SACR (X-SACR); (2) Ka-band SACR (Ka-SACR); and (3) W-band SACR (W-SACR). There are two SACRs on a single pedestal at each site where SACRs are deployed. The selection of the operating frequencies at each deployed site is predominantly determined by atmospheric attenuation at the site. Because RF attenuation increases with atmospheric water vapor content, ARM's Tropical Western Pacific (TWP) sites use the X-/Ka-band frequency pair. The Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites field the Ka-/W-band frequency pair. One ARM Mobile Facility (AMF1) has a Ka/W-SACR and the other (AMF2) has a X/Ka-SACR.

  2. The PROUST radar: First results

    NASA Technical Reports Server (NTRS)

    Bertin, F.; Cremieu, A.; Glass, M.; Massebeuf, M.; Petitdidier, M.

    1986-01-01

    Two campaigns took place in 1984 with the PROUST Radar operating in a bistatic mode, the transmitting antenna pointing at the vertical and the receiving one, 1 deg. off the vertical axis. The antenna beam intersection covers an altitude range between 3 and 9 km. The first of these campaigns are analyzed. The results analyzed show the capability of the PROUST Radar to measure the turbulent parameters and study the turbulence-wave interaction. In its present configuration (bistatic mode and 600 m vertical resolution), it has been necessary to make some assumptions that are known not to be truly fulfilled: homogeneous turbulence and constant vertical wind intensity over a 600-m thickness. It is clear that a more detailed study of the interaction between wave and turbulence will be possible with the next version of PROUST Radar (30-m altitude resolution and monostatic mode) that will soon be achieved.

  3. Spaceborne radar studies of Venus

    SciTech Connect

    Nozette, S.

    1980-01-01

    Data obtained from the Pioneer Venus radar mapper experiment are discussed. The mission was primarily developed to study the atmosphere of Venus. A highly eccentric orbit (eccentricity of 0.84, period of 24 h) was selected. The instrumentation has two operating modes: altimetry and imaging. Three parameters were measured for every radar spot size: altitude, surface roughness and radar reflectivity at a normal incidence. The measurements have been extended to a topographic map. The results suggest that the Beta region consists of two large shields and that the equatorial region is dominated by Aphrodite Terra. It also appears that the surface of Venus is very smooth and that it lacks great basins and the global plate tectonics present on earth.

  4. SMAP RADAR Processing and Calibration

    NASA Astrophysics Data System (ADS)

    West, R. D.; Jaruwatanadilok, S.; Kwoun, O.; Chaubell, M. J.

    2013-12-01

    The Soil Moisture Active Passive (SMAP) mission uses L-band radar and radiometer measurements to estimate soil moisture with 4% volumetric accuracy at a resolution of 10 km, and freeze-thaw state at a resolution of 1-3 km. Model sensitivities translate the soil moisture accuracy to a radar backscatter accuracy of 1 dB at 3 km resolution and a brightness temperature accuracy of 1.3 K at 40 km resolution. This presentation will describe the level 1 radar processing and calibration challenges and the choices made so far for the algorithms and software implementation. To obtain the desired high spatial resolution the level 1 radar ground processor employs synthetic aperture radar (SAR) imaging techniques. Part of the challenge of the SMAP data processing comes from doing SAR imaging on a conically scanned system with rapidly varying squint angles. The radar echo energy will be divided into range/Doppler bins using time domain processing algorithms that can easily follow the varying squint angle. For SMAP, projected range resolution is about 250 meters, while azimuth resolution varies from 400 meters to 1.2 km. Radiometric calibration of the SMAP radar means measuring, characterizing, and where necessary correcting the gain and noise contributions from every part of the system from the antenna radiation pattern all the way to the ground processing algorithms. The SMAP antenna pattern will be computed using an accurate antenna model, and then validated post-launch using homogeneous external targets such as the Amazon rain forest to look for uncorrected gain variation. Noise subtraction is applied after image processing using measurements from a noise only channel. Variations of the internal electronics are tracked by a loopback measurement which will capture most of the time and temperature variations of the transmit power and receiver gain. Long-term variations of system performance due to component aging will be tracked and corrected using stable external reference targets. Candidate targets include the Amazon rain forest and a model-corrected global ocean measurement. Radio frequency interference (RFI) signals are expected in the L-band frequency window used by the SMAP radar because many other users also operate in this band. Based on results of prior studies at JPL, SMAP L1 radar processing will use a "Slow-time thresholding" or STT algorithm to handle RFI contamination. The STT technique looks at the slow-time series associated with a given range sample, sets an appropriate threshold, and identifies any samples that rise above this threshold as RFI events. The RFI events are removed and the data are azimuth compressed without those samples. Faraday rotation affects L-band signals by rotating the polarization vector during propagation through the ionosphere. This mixes HH, VV, HV, and VH results with each other introducing another source of error. The SMAP radar is not fully polarimetric so the radar data do not provide a correction by themselves. Instead a correction must be derived from other sources. L1 radar processing will use estimates of Faraday rotation derived from externally supplied GPS-based measurements of the ionosphere total electron content (TEC). This work is supported by the SMAP project at the Jet Propulsion Laboratory, California Institute of Technology.

  5. WAVE-DRIVEN SURFACE FROM HF RADAR

    E-print Network

    Miami, University of

    FEATURE INTERNAL CURRENTS WAVE-DRIVEN SURFACE FROM HF RADAR By Lynn K. Shay Observations from-fre- quency (HF) radar have revealed that not only are the low-frequency and tidal currents resolved of the horizontal flow structure from HF radar pro- vides the spatial context for moored and ship- based

  6. Spaceborne imaging radar-C instrument

    Microsoft Academic Search

    BRYAN L. HUNEYCUTT

    1989-01-01

    The Shuttle Imaging Radar (SIR)-C instrument has been designed to obtain simultaneous multifrequency and simultaneous multipolarization radar images from a low Earth orbit. It is a multiparameter imaging radar that will be flown during two different seasons. The instrument has been designed to operate in innovative modes such as the squint mode, the extended aperture mode, and the scansar mode,

  7. High-power transmitters for radar applications

    Microsoft Academic Search

    Meppalli K. Shandas

    2009-01-01

    High-power transmitters are one of the critical elements in a radar system. The radar waveform needs to be amplified without distortion to the desired output power level by the high-power transmitter. In addition to affecting the overall performance of the radar system, the design of the transmitter affects many other factors, such as size, weight, power consumption, operating cost, reliability

  8. Radar geomorphology of coastal and wetland environments

    NASA Technical Reports Server (NTRS)

    Lewis, A. J.; Macdonald, H. C.

    1973-01-01

    Details regarding the collection of radar imagery over the past ten years are considered together with the geomorphic, geologic, and hydrologic data which have been extracted from radar imagery. Recent investigations were conducted of the Louisiana swamp marsh and the Oregon coast. It was found that radar imagery is a useful tool to the scientist involved in wetland research.

  9. Installed performance analysis of radar antenna systems

    Microsoft Academic Search

    Jacob J. Kim; Oren B. Kesler

    1998-01-01

    If modern airborne radar systems are to function properly, the radar antenna radiation patterns must meet certain specifications. Previously, most radar antennas were designed and tested in a clean antenna environment, i.e., there are no near field scattering from host structures, or radome effects. However, these higher order effects are a matter of increasing concern with added performance demands in

  10. Performance analysis of radar antenna systems

    Microsoft Academic Search

    J. J. Kim; O. B. Kesler

    1999-01-01

    If modern airborne radar systems are to function properly, the radar antenna radiation patterns must meet certain specifications. Until recently, most radar antennas were designed and tested in a clean antenna environment, i.e., there is no near field scattering from host structures or radome effects. However, these higher order effects are the matter of increasing concern with added performance demands

  11. Environmental effects on airborne radar performance

    Microsoft Academic Search

    William A. Skillman

    2011-01-01

    A radar is designed to meet customer specifications of range performance, angle accuracy, etc. However, an airborne radar must operate in an environment which may be different from the assumptions used in writing the performance specification. In an aircraft installation, the radar antenna is protected from the atmospheric environment by a radome which may introduce distortions and reflections of the

  12. 46 CFR 15.815 - Radar observers.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar observers. 15.815 Section 15.815...REQUIREMENTS Computations § 15.815 Radar observers. (a) Each person in...vessels of 300 gross tons or over which are radar equipped, shall hold an endorsement...

  13. 46 CFR 169.726 - Radar reflector.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar reflector. 169.726 Section 169...Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design...

  14. 46 CFR 15.815 - Radar observers.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar observers. 15.815 Section 15.815...REQUIREMENTS Computations § 15.815 Radar observers. (a) Each person in...vessels of 300 gross tons or over which are radar equipped, shall hold an endorsement...

  15. 46 CFR 167.40-40 - Radar.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar. 167.40-40 Section 167.40-40...Equipment Requirements § 167.40-40 Radar. All mechanically propelled vessels...coastwise service must be fitted with a marine radar system for surface navigation....

  16. 46 CFR 121.404 - Radars.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radars. 121.404 Section 121.404 Shipping... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph...Commission (FCC) type accepted general marine radar system for surface navigation with...

  17. 46 CFR 130.310 - Radar.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar. 130.310 Section 130.310 Shipping... Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the...

  18. 46 CFR 130.310 - Radar.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar. 130.310 Section 130.310 Shipping... Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the...

  19. 46 CFR 108.717 - Radar.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar. 108.717 Section 108.717 Shipping...Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1...coastwise service must have— (a) A marine radar system for surface navigation; and...

  20. 46 CFR 184.404 - Radars.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radars. 184.404 Section 184.404 Shipping... Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with...Commission (FCC) type accepted general marine radar system for surface navigation with...

  1. 46 CFR 11.480 - Radar observer.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar observer. 11.480 Section 11.480...Requirements for Deck Officers § 11.480 Radar observer. (a) This section contains...that an applicant must meet to qualify as a radar observer. (Part 15 of this chapter...

  2. 46 CFR 184.404 - Radars.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radars. 184.404 Section 184.404 Shipping... Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with...Commission (FCC) type accepted general marine radar system for surface navigation with...

  3. 46 CFR 167.40-40 - Radar.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar. 167.40-40 Section 167.40-40...Equipment Requirements § 167.40-40 Radar. All mechanically propelled vessels...coastwise service must be fitted with a marine radar system for surface navigation....

  4. 46 CFR 121.404 - Radars.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radars. 121.404 Section 121.404 Shipping... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph...Commission (FCC) type accepted general marine radar system for surface navigation with...

  5. 46 CFR 108.717 - Radar.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar. 108.717 Section 108.717 Shipping...Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1...coastwise service must have— (a) A marine radar system for surface navigation; and...

  6. 46 CFR 169.726 - Radar reflector.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Radar reflector. 169.726 Section 169...Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design...

  7. 46 CFR 11.480 - Radar observer.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Radar observer. 11.480 Section 11.480...Requirements for Deck Officers § 11.480 Radar observer. (a) This section contains...that an applicant must meet to qualify as a radar observer. (Part 15 of this chapter...

  8. Radar Technology Applied to Air Traffic Control

    Microsoft Academic Search

    WILLIAM W. SHRADER

    1973-01-01

    Use of primary radars for air traffic control (ATC) is discussed. The location and the parameters of various ATC radars are described. The clutter environment (land clutter, birds, automobiles, and weather) has had a major impact on the configuration of these radars. Signal-processing techniques and antenna techniques utilized to cope with the clutter are described. Future signal-processing techniques for the

  9. Radar target classification of commercial aircraft

    Microsoft Academic Search

    ANTHONY ZYWECK; ROBERT E. BOGNER

    1996-01-01

    With the increased availability of coherent wideband radars there has been a renewed interest in radar target recognition. A large bandwidth gives high resolution in range which means target discrimination may be possible. Coherence makes cross-range resolution and radar images possible. Some of the problems of classifying high resolution range profiles (HRRPs) are examined and simple preprocessing techniques which may

  10. The nature of bistatic and multistatic radar

    Microsoft Academic Search

    Wang Beide

    2001-01-01

    Bistatic and multistatic radar has some properties which are completely different from current monostatic radar. Some special properties that are closely related to tactical applications are derived. Through overall analysis, we believe that this will become one of the most important military radar systems

  11. Fifty years of bistatic and multistatic radar

    Microsoft Academic Search

    J. I. Glaser

    1986-01-01

    The article begins with a review of bistatic and multistatic radars, including the simultaneous introduction of radar technology in several countries during the 1930s and the various areas of technology development pursued by those countries. Technical descriptions are presented of nine different experimental systems. The article continues with a discussion of the potential military and nonmilitary advantages of bistatic radars

  12. Noise modulated multistatic surveillance radar concept

    Microsoft Academic Search

    Vesa-Jukka Salminen; Timo Lensu; Pekka Eskelinen; Simo Mertanen

    2006-01-01

    Noise modulated surveillance radars have many desirable properties. However, practical problems with signal processing and system design have inhibited noise modulated radars to become common. Fast improving signal processing will probably change this in future. We have studied what kind of noise modulated radar might be realistic in 15 years. Advantages are good LPI, good ECCM, good ARM avoidance, good

  13. Course Syllabus Course name: Radar Meteorology

    E-print Network

    Course Syllabus Course name: Radar Meteorology Course number: AT741 Instructor: Prof. Steven a foundational understanding of radar meteorology. Topics presented include microwave scattering theory, Doppler is to provide the student with a working knowledge of radar meteorology including applications to remote sensing

  14. Radar Soundings of the Ionosphere of Mars

    E-print Network

    Gurnett, Donald A.

    Radar Soundings of the Ionosphere of Mars D. A. Gurnett,1 * D. L. Kirchner,1 R. L. Huff,1 D. D4 We report the first radar soundings of the ionosphere of Mars with the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument on board the orbiting Mars Express spacecraft. Several types

  15. MIMO Phased-Array for SMTI Radar

    Microsoft Academic Search

    Jameson Bergin; Steven McNeil; Linda Fomundam; Peter A. Zulch

    2008-01-01

    Waveform diversity techniques for radar have gained considerable interest over the past several years. Novel radar waveforms have been proposed to improve detection performance and metric accuracy (i.e., angle estimation performance). This paper explores the potential for using a waveform diversity technique known as multiple input, multiple output (MIMO) radar to improve the detection performance of slow moving surface targets

  16. APPLICATION OF SENSOR SCHEDULING CONCEPTS TO RADAR

    E-print Network

    Nehorai, Arye

    Chapter 10 APPLICATION OF SENSOR SCHEDULING CONCEPTS TO RADAR William Moran University of Melbourne time illustrating the ideas on sensor schedul- ing in a specific context: that of a radar system. A typical pulse radar system operates by illuminating a scene with a short pulse of electromagnetic energy

  17. Dual-use air traffic control radar

    Microsoft Academic Search

    Lewis Buckler

    1998-01-01

    During the past seven years the Federal Aviation Administration has had a research program called the Terminal Area Surveillance System (TASS) to develop the next generation airport surveillance radar. At present the FAA has two radars for aircraft and weather surveillance at the major airports. One of these radars, the ASR-9, is for aircraft surveillance and rain intensity. The other,

  18. ESTIMATING HYDROGEOLOGIC PARAMETERS FROM RADAR DATA

    Microsoft Academic Search

    Charles T. Young

    Radar reflections for a layered medium are dependant on the dielectric constants of the layers, which is closely linked to saturated porosity, and more loosely to hydraulic conductivity. Radar data have been obtained at a site where hydraulic conductivity has been measured in great detail. The radar cross section from the site clearly shows layering within the section, and it

  19. AESA upgrade option for Eurofighter Captor radar

    Microsoft Academic Search

    M. Barclay; U. Pietzschmann; G. Gonzalez; P. Tellini

    2008-01-01

    The Euroradar consortium has successfully developed and demonstrated an AESA technology upgrade for the Eurofighter Typhoon Captor radar. This technology demonstrator, designated CAESAR, enables E-scan capability to be fully exploited by the existing Captor radar, while retaining all features and capabilities of the original system. Advanced waveforms, designed and optimised for electronically scanned radar systems, have been evaluated in recent

  20. AESA upgrade option for Eurofighter Captor Radar

    Microsoft Academic Search

    M. Barclay; U. Pietzschmann; G. Gonzalez; P. Tellini

    2010-01-01

    The Euroradar Consortium has successfully developed and demonstrated an Active Electronically Scanned Array (AESA) technology upgrade for the Eurofighter Typhoon Captor Radar. This technology demonstrator, designated Captor Active Electronically Scanned Array Radar (CAESAR), enables E-scan capability to be fully exploited by the existing Captor radar, while retaining all features and capabilities of the original system. Advanced waveforms, designed and optimized

  1. Nonsinusoidal radar signal design for stealth targets

    Microsoft Academic Search

    Nasser J. Mohamed

    1995-01-01

    The detection of stealth point targets challenges the design of conventional radars using sinusoidal carriers since the objective of stealth technology is to reduce the radar cross section (RCS) of targets to a level where the radar receiver cannot detect the target. While there are a number of techniques employing different technologies to reduce the RCS of targets, shaping and

  2. Optimum Radar Parameters for Mapping Soil Moisture

    Microsoft Academic Search

    Fawwaz Ulaby; Percy Batlivala

    1976-01-01

    The radar response to soil moisture content was experimentally determined for each of three bare fields with considerably different surface roughnesses at eight frequencies in the 2-8 GHz band for HH and VV polarizations. Analysis of the data indicates that the effect of roughness on the radar backscattering coefficient can be minimized by proper choice of the radar parameters. If,

  3. Overview of hydros radar soil moisture algorithm

    Microsoft Academic Search

    Yunjin Kim; Jakob van Zyl

    2005-01-01

    In this paper, we will describe the Hydros algorithms to derive soil moisture from L-band polarimetric radar measurements. The baseline Hydros radar algorithm to estimate soil moisture is composed of three steps: land classification, preliminary soil moisture estimation, and final time-series improvement. Before soil moisture is estimated using Hydros radar data, each pixel will be classified in order to apply

  4. Hybrid array architectures for BMD radar systems

    Microsoft Academic Search

    J. Frank; J. D. Richards; A. Agrawal

    2003-01-01

    The proliferation of long range ballistic missiles has increased the need for radars capable of supporting early midcourse and ascent phase intercepts. In order to support these early midcourse and ascent phase intercepts, the ballistic missile defense (BMD) radar should be forward deployed. While a sea-based capability can be forward deployed, an easily transportable ground-based radar would be advantageous in

  5. Radar test range design considerations

    NASA Astrophysics Data System (ADS)

    Sofianos, D.

    1980-04-01

    This report presents considerations for and the preliminary design of a synthetic aperture RADAR (SAR) test range. The purpose is to present a methodology and conceptual design for a Flexible Test Bed (FTB) digital processor operational test. The objectives of this operational test are to: (1) determine whether the processor modifications improved image quality, (2) establish a processor performance baseline, and (3) determine whether the system will attain desired levels of probability of detection. It is assumed that SAI would develop a test design while GAC will fabricate and install the required radar test range.

  6. Results from a Grazing Incidence X-Ray Interferometer

    NASA Technical Reports Server (NTRS)

    Joy, Marshall K.; Shipley, Ann; Cash, Webster; Carter, James

    2000-01-01

    A prototype grazing incidence interferometer has been built and tested at EUV and X-ray wavelengths using a 120 meter long vacuum test facility at Marshall Space Flight Center. We describe the design and construction of the interferometer, the EUV and x-ray sources, the detector systems, and compare the interferometric fringe measurements with theoretical predictions. We also describe the next-generation grazing incidence system which is designed to provide laboratory demonstration of key technologies that will be needed for a space-based x-ray interferometer.

  7. Integrated heterodyne interferometer with on-chip modulators and detectors.

    PubMed

    Cole, David B; Sorace-Agaskar, Cheryl; Moresco, Michele; Leake, Gerald; Coolbaugh, Douglas; Watts, Michael R

    2015-07-01

    We demonstrate, to our knowledge, the first on-chip heterodyne interferometer fabricated on a 300-mm CMOS compatible process that exhibits root-mean-square (RMS) position noise on the order of 2 nm. Measuring 1 mm by 6 mm, the interferometer is also, to our knowledge, the smallest heterodyne interferometer demonstrated to date and will surely impact numerous interferometric and metrology applications, including displacement measurement, laser Doppler velocimetry and vibrometry, Fourier transform spectroscopy, imaging, and light detection and ranging (LIDAR). Here we present preliminary results that demonstrate the displacement mode. PMID:26125376

  8. Compact phase-shifted Sagnac interferometer for ultrasound detection

    NASA Astrophysics Data System (ADS)

    Fomitchov, P. A.; Krishnaswamy, S.; Achenbach, J. D.

    1997-09-01

    A compact fibre, phase-shifted Sagnac interferometer for ultrasound detection has been developed. The interferometer is a truly path-matched device, and therefore requires no path stabilization or heterodyning. It is a less expensive and more robust alternative to the heterodyne or path-stabilized Michelson interferometer. The device provides high spatial resolution of ultrasonic detection. It has been used in conjunction with conventional piezoelectric transducers (PZT) to detect Rayleigh and Lamb waves and to image a crack in a thin plate, rivet cracks in riveted plates, and for ultrasonic beam profiling.

  9. Fourier-transform and global contrast interferometer alignment methods

    DOEpatents

    Goldberg, Kenneth A. (Berkeley, CA)

    2001-01-01

    Interferometric methods are presented to facilitate alignment of image-plane components within an interferometer and for the magnified viewing of interferometer masks in situ. Fourier-transforms are performed on intensity patterns that are detected with the interferometer and are used to calculate pseudo-images of the electric field in the image plane of the test optic where the critical alignment of various components is being performed. Fine alignment is aided by the introduction and optimization of a global contrast parameter that is easily calculated from the Fourier-transform.

  10. Phase-shifting (Sagnac) interferometer with external phase control.

    PubMed

    Ferrari, José A; Garbusi, Eugenio

    2005-07-20

    A novel ring configuration for phase-shifting interferometry with external phase-shifting control is presented. The device is a polarization (ring) interferometer, in which the reference and test arms are parts of the same collimated beam. The key point is to manage the polarization of the light such that orthogonal linear polarizations describe counterpropagating paths in the ring interferometer. The phase shift between the two waves is externally controlled with a Pockels cell, which permits fast phase modulation without the need for moving parts inside the interferometer. PMID:16047900

  11. Quantum noise in gravitational wave interferometers: an overview and recent developments

    Microsoft Academic Search

    Thomas Corbitt; Nergis Mavalvala

    2003-01-01

    We present an overview of quantum noise in gravitational wave interferometers. Gravitational wave detectors are extensively modified variants of a Michelson interferometer and the quantum noise couplings are strongly influenced by the interferometer configuration. We describe recent developments in the treatment of quantum noise in the complex interferometer configurations of present-day and future gravitational-wave detectors. In addition, we explore prospects

  12. Radar volcano monitoring system in Iceland

    NASA Astrophysics Data System (ADS)

    Arason, Þórður; Yeo, Richard F.; Sigurðsson, Geirfinnur S.; Pálmason, Bolli; von Löwis, Sibylle; Nína Petersen, Guðrún; Bjornsson, Halldór

    2013-04-01

    Weather radars are valuable instruments in monitoring explosive volcanic eruptions. Temporal variations in the eruption strength can be monitored as well as variations in plume and ash dispersal. Strength of the reflected radar signal of a volcanic plume is related to water content and droplet sizes as well as type, shape, amount and the grain size distribution of ash. The Icelandic Meteorological Office (IMO) owns and operates three radars and one more is planned for this radar volcano monitoring system. A fixed position 250 kW C-band weather radar was installed in 1991 in SW-Iceland close to Keflavík International Airport, and upgraded to a doppler radar in 2010. In cooperation with the International Civil Aviation Organization (ICAO), IMO has recently invested in two mobile X-band radars and one fixed position C-band radar. The fixed position 250 kW doppler C-band weather radar was installed in April 2012 at Fljótsdalsheiði, E-Iceland, and in June 2012 IMO received a mobile 65 kW dual-polarization doppler X-band radar. Early in 2013 IMO will acquire another mobile radar of the same type. Explosive volcanic eruptions in Iceland during the past 22 years were monitored by the Keflavík radar: Hekla 1991, Gjálp 1996, Grímsvötn 1998, Hekla 2000, Grímsvötn 2004, Eyjafjallajökull 2010 and Grímsvötn 2011. Additionally, the Grímsvötn 2011 eruption was mointored by a mobile X-band radar on loan from the Italian Civil Protection Authorities. Detailed technical information is presented on the four radars with examples of the information acquired during previous eruptions. This expanded network of radars is expected to give valuable information on future volcanic eruptions in Iceland.

  13. L-band radar scattering from grass

    NASA Technical Reports Server (NTRS)

    Chauhan, N.; O'Neill, P.; Le Vine, D.; Lang, R.; Khadr, N.

    1992-01-01

    A radar system based on a network analyzer has been developed to study the backscatter from vegetation. The radar is operated at L-band. Radar measurements of a grass field were made in 1991. The radar returns from the grass were measured at three incidence angles. Ground truth and canopy parameters such as blade and stem dimensions, moisture content of the grass and the soil, and blade and stem density, were measured. These parameters are used in a distorted Born approximation model to compute the backscatter coefficients from the grass layer. The model results are compared with the radar data.

  14. Radar in the wake of WARC

    NASA Astrophysics Data System (ADS)

    Tompkins, R. D.

    1981-08-01

    The World Administrative Radio Conference of 1979 (WARC-79) will have a significant effect on the design, development, and operation of radar systems. This paper discusses the changes in the Table of Frequency Allocations which will affect radar and notes some of the problems which will be faced by the radar community in maintaining system performance requirements. An urgent need is shown for expanding the participation by radar developers in the affairs of the International Radio Consultative Committee (CCIR). This participation is essential to create and maintain a technical basis for radar which will define spectrum needs, examine spectrum usage, and describe techniques for efficient spectrum utilization within the International Telecommunications Union (ITU).

  15. Giant Eyes for the VLT Interferometer

    NASA Astrophysics Data System (ADS)

    2001-11-01

    First Scientific Results with Combined Light Beams from Two 8.2-m Unit Telescopes Summary It started as a preparatory technical experiment and it soon developed into a spectacular success. Those astronomers and engineers who were present in the control room that night now think of it as the scientific dawn of the Very Large Telescope Interferometer (VLTI) . On October 29, 2001, ANTU and MELIPAL , two of the four VLT 8.2-m Unit Telescopes at the ESO Paranal Observatory, were linked for the first time. Light from the southern star Achernar (Alpha Eridani) was captured by the two telescopes and sent to a common focus in the observatory's Interferometric Laboratory. Following careful adjustments of the optical paths, interferometric fringes were soon recorded there, proving that the beams from the two telescopes had been successfully combined "in phase" . From an analysis of the observed pattern (the "fringe contrast"), the angular diameter of Achernar was determined to be 1.9 milli-arcsec. At the star's distance (145 light-years), this corresponds to a size of 13 million km. The observation is equivalent to measuring the size of a 4-metre long car on the surface of the Moon. This result marks the exciting starting point for operations with the Very Large Telescope Interferometer (VLTI) and it was immediately followed up by other scientific observations. Among these were the first measurements of the diameters of three red dwarf stars ("Kapteyn's star" - HD 33793, HD 217987 and HD 36395), a precise determination of the variable diameters of the pulsating Cepheid stars Beta Doradus and Zeta Geminorum (of great importance for the calibration of the universal distance scale), as well as a first interferometric measurement of the core of Eta Carinae , an intriguing, massive southern object that may possibly become the next supernova in our galaxy. This milestone is another important step towards the ultimate goal of the VLT project - to combine all four 8.2-m telescopes into the most powerful optical/infrared telescope system on Earth. When ready, it will be able to reveal at least 15 times finer details in astronomical objects than what is possible with any existing, single ground-based telescope. PR Photo 30a/01 : Overview of the VLT Interferometer . PR Photo 30b/01 : "Joint" stellar light-spot produced via ANTU and MELIPAL at the VLTI focus. PR Photo 30c/01 : Interferometric fringes from the star Achernar . PR Photo 30d/01 : Time sequence of fringes from Achernar. PR Photo 30e/01 : "Visibility curve" of the star Psi Phoenicis . Scientific Appendix First VLTI observations with two 8.2-m telescopes ESO PR Photo 30a/01 ESO PR Photo 30a/01 [Preview - JPEG: 357 x 400 pix - 82k] [Normal - JPEG: 713 x 800 pix - 208k] [Hi-Res - JPEG: 2673 x 3000 pix - 1.4M] ESO PR Photo 30b/01 ESO PR Photo 30b/01 [Preview - JPEG: 400 x 350 pix - 57k] [Normal - JPEG: 800 x 700 pix - 176k] Caption : PR Photo 30a/01 : Overview of the VLT Interferometer as it was operated when the light beams from two of the 8.2-m telescopes were combined. The VINCI instrument that was used for the present test, is located at the common focus in the Interferometric Laboratory. PR Photo 30b/01 shows one of the first "joint" light-spots from a star as seen at this VLTI focus and resulting from the superposition of light collected with the 8.2-m VLT ANTU and MELIPAL telescopes. Despite the long optical paths (about 200 m), the quality is excellent (FWHM = 0.45 arcsec). Note that this is not (yet) an image of the stellar surface. At 1 o'clock in the morning of October 30, 2001, ESO astronomers and engineers working in the VLTI Control Room successfully combined the light from ANTU and MELIPAL , two of the four 8.2-m VLT Unit Telescopes at the Paranal Observatory. The same night, a series of high-resolution test observations with the VINCI instrument [1] at the focus of the VLT Interferometer (VLTI) proved that this complex system was functioning extremely well, and within the technical specifications . Following abo

  16. Enhanced Weather Radar (EWxR) System

    NASA Technical Reports Server (NTRS)

    Kronfeld, Kevin M. (Technical Monitor)

    2003-01-01

    An airborne weather radar system, the Enhanced Weather Radar (EWxR), with enhanced on-board weather radar data processing was developed and tested. The system features additional weather data that is uplinked from ground-based sources, specialized data processing, and limited automatic radar control to search for hazardous weather. National Weather Service (NWS) ground-based Next Generation Radar (NEXRAD) information is used by the EWxR system to augment the on-board weather radar information. The system will simultaneously display NEXRAD and on-board weather radar information in a split-view format. The on-board weather radar includes an automated or hands-free storm-finding feature that optimizes the radar returns by automatically adjusting the tilt and range settings for the current altitude above the terrain and searches for storm cells near the atmospheric 0-degree isotherm. A rule-based decision aid was developed to automatically characterize cells as hazardous, possibly-hazardous, or non-hazardous based upon attributes of that cell. Cell attributes are determined based on data from the on-board radar and from ground-based radars. A flight path impact prediction algorithm was developed to help pilots to avoid hazardous weather along their flight plan and their mission. During development the system was tested on the NASA B757 aircraft and final tests were conducted on the Rockwell Collins Sabreliner.

  17. Cognitive radar: A way forward

    Microsoft Academic Search

    Michael Wicks

    2011-01-01

    The desire to autonomously anticipate, find, fix, track, target, engage, and assess, anything, anytime, anywhere (AF2T2EA4) in spectrally dense environments will require changes to how we build, modify, and deploy radar and radio frequency systems. These spectrally dense environments coupled with the twenty-first century threat are already causing havoc throughout the world.

  18. Spatial Coverage of Radar Reflectors

    Microsoft Academic Search

    Daniel Levine; William H. Welch

    1964-01-01

    Passive reflectors may be employed to enhance the radar return of a space vehicle for some phases of tracking, as in orbital rendezvous. Contour charts prepared on a suitable base grid provide an objective means of evaluating the spatial coverage of different designs for this application. The superiority of a circular corner reflector over square or triangular designs is demonstrated

  19. CFAR detection for multistatic radar

    Microsoft Academic Search

    Vahideh Amanipour; Ali Olfat

    2011-01-01

    In this paper a multistatic radar system with n transmitters and one receiver is considered and several constant false alarm rate (CFAR) algorithms for detection are introduced. The decision statistics of the proposed detectors are the sum of the n largest returning signals in an array of N+n range cells. It is shown that the proposed decision statistic satisfies the

  20. Solid-state radar transmitters

    Microsoft Academic Search

    E. D. Ostroff; M. Borkowski; H. Thomas; J. Curtis

    1985-01-01

    The technology and design procedures for introducing transistors into radio transmitters are discussed. The design characteristics of solid-state radar transmitters are described, with emphasis given to power amplifier\\/modules and devices for summing the output power in space or in an output combiner. Some design issues related to power supplies, pulse waveform amplitude regulation; reliability; and cost; and also considered. Some

  1. Pioneer Venus radar mapper experiment

    USGS Publications Warehouse

    Pettengill, G.H.; Ford, P.G.; Brown, W.E.; Kaula, W.M.; Keller, C.H.; Masursky, H.; McGill, G.E.

    1979-01-01

    Altimetry and radar scattering data for Venus, obtained from 10 of the first 13 orbits of the Pioneer Venus orbiter, have disclosed what appears to be a rift valley having vertical relief of up to 7 kilometers, as well as a neighboring, gently rolling plain. Planetary oblateness appears unlikely to exceed 112500 and may be substantially smaller. Copyright ?? 1979 AAAS.

  2. Test equipment for coherent radar

    Microsoft Academic Search

    D. B. Leeson; W. K. Saunders

    1974-01-01

    Test equipment for pulsed Doppler and CW coherent radar is described. Equipment developed for testing the Vulcan tracking system is discussed, and the test procedure is outlined. The Vulcan equipment provides measurements of STAMO quality, the additive noise contributed by the sideband modulator and klystron amplifier, limitations on subclutter visibility and the minimum detected signal in the receiving chain, lock

  3. Radar Imagery of Oil Slicks

    Microsoft Academic Search

    R. O. Pilon; C. G. Purves

    1973-01-01

    A joint agency controlled oil slick experiment, sponsored by the United States Coast Guard, was conducted in the Pacific Ocean in the Fall of 1970. The Naval Research Laboratory's synthetic aperature radar was used to detect and monitor the slicks at frequencies of 428, 1228, 4455, and 8910 MHz during the low sea state conditions encountered. At frequencies of 1228

  4. UK airborne AESA radar research

    Microsoft Academic Search

    Stephen Moore

    2010-01-01

    This reviews current UK airborne active electronically scanned array (AESA) designs, discusses current trends toward higher digitisation and multi-function aperture concepts, and details key future challenges that this technology faces. Specifically, we discuss applications to fast-jets. Key requirements are for higher levels of digitisation to provide the performance required in ECCM, STAP, GMTI, and ESM modes. Building radar systems with

  5. Fractal radar scattering from soil.

    PubMed

    Oleschko, Klaudia; Korvin, Gabor; Figueroa, Benjamin; Vuelvas, Marco Antonio; Balankin, Alexander S; Flores, Lourdes; Carreón, Dora

    2003-04-01

    A general technique is developed to retrieve the fractal dimension of self-similar soils through microwave (radar) scattering. The technique is based on a mathematical model relating the fractal dimensions of the georadargram to that of the scattering structure. Clear and different fractal signatures have been observed over four geosystems (soils and sediments) compared in this work. PMID:12786363

  6. Radar attenuation in desert soil

    Microsoft Academic Search

    Gary Koh

    2008-01-01

    Soil properties make a significant impact in the observed responses of various sensors for subsurface target detection. Ground penetrating radars (GPRs) have been extensively researched as a tool for subsurface target detection. A key soil parameter of interest for evaluating GPR performance is the soil attenuation rate. The information about the soil attenuation rate coupled with target properties (size, shape,

  7. Fractal radar scattering from soil

    Microsoft Academic Search

    Klaudia Oleschko; Gabor Korvin; Benjamin Figueroa; Marco Antonio Vuelvas; Alexander S. Balankin; Lourdes Flores; Dora Carreón

    2003-01-01

    A general technique is developed to retrieve the fractal dimension of self-similar soils through microwave (radar) scattering. The technique is based on a mathematical model relating the fractal dimensions of the georadargram to that of the scattering structure. Clear and different fractal signatures have been observed over four geosystems (soils and sediments) compared in this work.

  8. Switchable multiwavelength filter based on a hybrid sagnac interferometer

    NASA Astrophysics Data System (ADS)

    Shim, Young Bo; Han, Young-Geun

    2012-04-01

    A switchable multichannel filter based on a hybrid Sagnac interferometer was proposed and experimentally demonstrated. The hybrid Sagnac interferometer was realized by inserting a sampled fiber Bragg grating (SFBG) into a fiber loop mirror by using a polarization-insensitive 3-dB coupler. By using a beam scanning technique, we fabricated a sampled fiber Bragg grating by exposing a photosensitive fiber to a frequency-doubled 244-nm Ar+ laser. The fabricated SFBG had multiple reflection peaks corresponding to the chirp ratio and the spacing of grating. The multiple peaks in the hybrid Sagnac interferometer could be controlled by changing the relative phase difference between two counter-propagating signals. The transmission characteristics of the proposed switchable multichannel filter were analyzed by using a Jones matrix method. Consequently, a switchable multichannel filter based on a sampled fiber Bragg grating incorporating a Sagnac interferometer could be achieved.

  9. Novel pressure sensor with a Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Li, Zhiquan; Fan, Lina; Qiang, Xifu

    2000-10-01

    A novel pressure sensor using a fiber Fabry-Perot interferometer (FFPI) has been developed in this paper. We use the internal F-P cavity pressure sensor in our research. Micromachined Fabry-Perot microcavity structures have been investigated for use as a pressure sensor. The single-mode fiber containing the interferometer is bonded at one end to the stainless-steel diaphragm and is also attached under longitudinal tension beyond the interferometer. An analysis relating the expected interferometer phase change to pressure is presented. And the dynamic response of FFPI sensor to pressure changes produced by an air pump is in good agreement with that measured with a conventional pressure sensor. The sensor is suitable for operation with other signal-processing and multiplexing schemes.

  10. Application of fixed delay Michelson interferometer for radial velocity measurement

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Jiang, Mingda; Zhu, Yongtian

    2010-07-01

    Fixed Delay Michelson Interferometer (FDMI) also called Wide-Angle Michelson Interferometer (WAMI) is different from conventional Michelson interferometer. Its fixed delay is not only useful to widen the field of view, but also improve the accuracy of RV measurement. So it's widely known that works well on upper atmospheric wind study by measuring the Doppler shift of single emission lines. On the other hand, a new technique called External Dispersed Interferometry (EDI) can efficiently overcome the fundamental limitation of narrow bandpass of interferometer by combination between FDMI and post-disperser. The related instruments have been successfully used in the exoplanet exploration field. In this paper, the FDMI concept and its application in these two fields are reviewed, and a major astronomical project in China, which is developing a multi-object exoplanet survey system (MESS) based on FDMI, is introduced.

  11. Mission analysis for the Laser Interferometer Space Antenna (LISA) mission

    NASA Astrophysics Data System (ADS)

    Hechler, F.; Folkner, W. M.

    2003-10-01

    The interplanetary orbits of three pairs of spacecraft, forming three laser interferometers, are designed such that their separations, i.e. the lengths of the interferometer arms, remain nearly constant. Each spacecraft pair is located near the vertex of a rotating equilateral triangle formed by the individual orbits of the spacecraft about the Sun. Feasible spacecraft masses are computed for a scenario with an Ariane 5 launch into a Geostationary Transfer Orbit (GTO) and a three-burn transfer from the GTO to the triangular configuration. The relative motion is perturbed by planetary gravity. However, the arm rate differences degrading the interferometer accuracy can be kept below certain limits by choosing optimum initial conditions and/or by controlling them by occasional orbit adjustment manoeuvres. The achievable orbit determination accuracy is given for systems processing two-way range and Doppler data collected on ground and/or laser interferometer measurements of the rate of change of distance between spacecraft.

  12. Searching for Gravitational Waves with a Geostationary Interferometer

    E-print Network

    M. Tinto; J. C. N. de Araujo; O. D. Aguiar; M. E. S. Alves

    2013-08-16

    We analyze the sensitivities of a geostationary gravitational wave interferometer mission operating in the sub-Hertz band. Because of its smaller armlength, in the lower part of its accessible frequency band ($10^{-4} - 2 \\times 10^{-2}$ Hz) our proposed Earth-orbiting detector will be less sensitive, by a factor of about seventy, than the Laser Interferometer Space Antenna (LISA) mission. In the higher part of its band instead ($2 \\times 10^{-2} - 10$ Hz), our proposed interferometer will have the capability of observing super-massive black holes (SMBHs) with masses smaller than $\\sim 10^{6}$ M$_{\\odot}$. With good event rates for these systems, a geostationary interferometer will be able to accurately probe the astrophysical scenarios that account for their formation.

  13. Overview of the control for the Keck Interferometer

    NASA Technical Reports Server (NTRS)

    Booth, A. J.; Eychaner, G.; Hovland, E.; Johnson, R.; Lupton, W.; Niessner, A.; Palmer, D.; Reder, L.; Rudeen, A.; Smythe, R.; Tsubota, K.

    2002-01-01

    This paper gives an overview of the control system that has been implemented for the single baseline operation of the Keck Interferometer and indicates how this will be extended to allow control of the future modes of the instrument.

  14. Direct reading fast microwave interferometer for ELMO Bumpy Torus

    SciTech Connect

    Uckan, T.

    1984-11-01

    A simple and inexpensive 4-mm direct reading fast (rise timeapprox.100 ..mu..s) microwave interferometer is described. The system is particularly useful for density measurements on the ELMO Bumpy Torus (EBT) during pulsed operation.

  15. Broadband detuned Sagnac interferometer for future generation gravitational wave astronomy

    E-print Network

    Voronchev, N V; Danilishin, S L

    2015-01-01

    Broadband suppression of quantum noise below the Standard Quantum Limit (SQL) becomes a top-priority problem for the future generation of large-scale terrestrial detectors of gravitational waves, as the interferometers of the Advanced LIGO project, predesigned to be quantum-noise-limited in the almost entire detection band, are phased in. To this end, among various proposed methods of quantum noise suppression or signal amplification, the most elaborate approach implies a so-called *xylophone* configuration of two Michelson interferometers, each optimised for its own frequency band, with a combined broadband sensitivity well below the SQL. Albeit ingenious, it is a rather costly solution. We demonstrate that changing the optical scheme to a Sagnac interferometer with weak detuned signal recycling and frequency dependent input squeezing can do almost as good a job, as the xylophone for significantly lower spend. We also show that the Sagnac interferometer is more robust to optical loss in filter cavity, used f...

  16. Gravitational wave detection with single-laser atom interferometers

    E-print Network

    Nan Yu; Massimo Tinto

    2010-03-22

    We present a new general design approach of a broad-band detector of gravitational radiation that relies on two atom interferometers separated by a distance L. In this scheme, only one arm and one laser will be used for operating the two atom interferometers. We consider atoms in the atom interferometers not only as perfect inertial reference sensors, but also as highly stable clocks. Atomic coherence is intrinsically stable and can be many orders of magnitude more stable than a laser. The unique one-laser configuration allows us to then apply time-delay interferometry to the responses of the two atom interferometers, thereby canceling the laser phase fluctuations while preserving the gravitational wave signal in the resulting data set. Our approach appears very promising. We plan to investigate further its practicality and detailed sensitivity analysis.

  17. Single and double bracewell nulling interferometer in space

    NASA Technical Reports Server (NTRS)

    Velusamy, T.; Angel, R. P.; Eatchel, A.; Tenerelli, D.; Woolf, N. J.

    2003-01-01

    As part of a NASA NRA study we have examined the design and use of a small Bracewell nulling interferometer in space for observations of Jovian and terrestrial planets in the 4-12 mu m spectral region.

  18. "First Light" for the VLT Interferometer

    NASA Astrophysics Data System (ADS)

    2001-03-01

    Excellent Fringes From Bright Stars Prove VLTI Concept Summary Following the "First Light" for the fourth of the 8.2-m telescopes of the VLT Observatory on Paranal in September 2000, ESO scientists and engineers have just successfully accomplished the next major step of this large project. On March 17, 2001, "First Fringes" were obtained with the VLT Interferometer (VLTI) - this important event corresponds to the "First Light" for an astronomical telescope. At the VLTI, it occurred when the infrared light from the bright star Sirius was captured by two small telescopes and the two beams were successfully combined in the subterranean Interferometric Laboratory to form the typical pattern of dark and bright lines known as " interferometric fringes ". This proves the success of the robust VLTI concept, in particular of the "Delay Line". On the next night, the VLTI was used to perform a scientific measurement of the angular diameter of another comparatively bright star, Alpha Hydrae ( Alphard ); it was found to be 0.00929±0.00017 arcsec . This corresponds to the angular distance between the two headlights of a car as seen from a distance of approx. 35,000 kilometres. The excellent result was obtained during a series of observations, each lasting 2 minutes, and fully confirming the impressive predicted abilities of the VLTI . This first observation with the VLTI is a monumental technological achievement, especially in terms of accuracy and stability . It crucially depends on the proper combination and functioning of a large number of individual opto-mechnical and electronic elements. This includes the test telescopes that capture the starlight, continuous and extremely precise adjustment of the various mirrors that deflect the light beams as well as the automatic positioning and motion of the Delay Line carriages and, not least, the optimal tuning of the VLT INterferometer Commissionning Instrument (VINCI). These initial observations prove the overall concept for the VLTI . It was first envisaged in the early 1980's and has been continuously updated, as new technologies and materials became available during the intervening period. The present series of functional tests will go on for some time and involve many different configurations of the small telescopes and the instrument. It is then expected that the first combination of light beams from two of the VLT 8.2-m telescopes will take place in late 2001 . According to current plans, regular science observations will start from 2002, when the European and international astronomical community will have access to the full interferometric facility and the specially developed VLTI instrumentation now under construction. A wide range of scientific investigations will then become possible, from the search for planets around nearby stars, to the study of energetic processes at the cores of distant galaxies. With its superior angular resolution (image sharpness), the VLT is now beginning to open a new era in observational optical and infrared astronomy. The ambition of ESO is to make this type of observations available to all astronomers, not just the interferometry specialists. Video Clip 03/01 : Various video scenes related to the VLTI and the "First Fringes". PR Photo 10a/01 : "First Fringes" from the VLTI on the computer screen. PR Photo 10b/01 : Celebrating the VLTI "First Fringes" . PR Photo 10c/01 : Overview of the VLT Interferometer . PR Photo 10d/01 : Interferometric observations: Fringes from two stars of different angular size . PR Photo 10e/01 : Interferometric observations: Change of fringes with increasing baseline . PR Photo 10f/01 : Aerial view of the installations for the VLTI on the Paranal platform. PR Photo 10g/01 : Stations for the VLTI Auxiliary Telescopes. PR Photo 10h/01 : A test siderostat in place for observations. PR Photo 10i/01 : A test siderostat ( close-up ). PR Photo 10j/01 : One of the Delay Line carriages in the Interferometric Tunnel. PR Photo 10k/01 : The VINCI instrume

  19. Planetary Radars Operating Centre PROC

    NASA Astrophysics Data System (ADS)

    Catallo, C.; Flamini, E.; Seu, R.; Alberti, G.

    2007-12-01

    Planetary exploration by means of radar systems, mainly using Ground Penetrating Radars (GPR) plays an important role in Italy. Numerous scientific international space programs are currently carried out jointly with ESA and NASA by Italian Space Agency, the scientific community and the industry. Three important experiments under Italian leadership ( designed and manufactured by the Italian industry), provided by ASI either as contribution to ESA programs either within a NASA/ASI joint venture framework, are now operating: MARSIS on-board Mars Express, SHARAD on-board Mars Reconnaissance Orbiter and CASSINI Radar on-board Cassini spacecraft. In order to support all the scientific communities, institutional customers and experiment teams operation three Italian dedicated operational centers have been realized, namely SHOC, (Sharad Operating Centre), MOC (Marsis Operating Center) and CASSINI PAD ( Processing Altimetry Data). Each center is dedicated to a single instrument management and control, data processing and distribution. Although they had been conceived to operate autonomously and independently one from each other, synergies and overlaps have been envisaged leading to the suggestion of a unified center, the Planetary Radar Processing Center (PROC). PROC is conceived in order to include the three operational centers, namely SHOC, MOC and CASSINI PAD, either from logistics point of view and from HW/SW capabilities point of view. The Planetary Radar Processing Center shall be conceived as the Italian support facility to the scientific community for on-going and future Italian planetary exploration programs. Therefore, scalability, easy use and management shall be the design drivers. The paper describes how PROC is designed and developed, to allow SHOC, MOC and CASSINI PAD to operate as before, and to offer improved functionalities to increase capabilities, mainly in terms of data exchange, comparison, interpretation and exploitation. Furthermore, in the frame of an operative experimental platform, where a specific payload ( to be developed by the Italian Industry) a GPR will be accommodated on-board the Italian Space Agency stratospheric balloon and the data analysed by PROC; as a minimum two flight campaigns over polar regions are foreseen. The system shall be capable of acquiring radar data upon scientists requests in order to help them refine their models, experiment new algorithms, improve data interpretation capabilities. The paper also describes how the system will be integrated in the PROC, sharing the operational resources and aiding scientists to increase their knowledge in the field of surface radar sounding. A specific PROC Web facility is foreseen to allow data gathering, request submission, data exchange and dissemination.

  20. VHF radar and rocket observations of equatorial spread F on Kwajalein

    SciTech Connect

    Hysell, D.L.; Kelley, M.C.; Swartz, W.E.; Farley, D.T. [Cornell Univ., Ithaca, NY (United States)] [Cornell Univ., Ithaca, NY (United States)

    1994-08-01

    VHF radar data from the Summer 1990 Equatorial Spread F campaign on Kwajalein are presented. The Cornell 50 MHz portable radar interferometer (CUPRI) operated concurrently with the Altair UHF incoherent scatter radar throughout July and August and supported two sounding rocket flights on July 30 and August 2. This experiment provided the first opportunity to simultaneously diagnose equatorial spread F using the three prime experimental techniques: VHF/UHF coherent scatter, incoherent scatter, and in situ probe measurements of electric field and density fluctuations. The intensity of the coherent echoes observed was consistent with typical Jicamarca spread F observations, but chains of periodic, large-scale plasma upwellings were observed more often and for much longer durations on Kwajalein than have been seen over Peru. CUPRI also measured Doppler frequencies in one upwelling corresponding to 1200-m/s plasma drift velocities. This measurement agrees with recent observations of supersonic drift rates at the magnetic equator by spacecraft. Near the most active localized plasma upwellings, interferometer data reveal that the zonal drift rate of plasma irregularities can vary sharply in space, as one would expect for two-dimensional incompressible flow. The authors introduce a semiempirical model of the three-dimensional spectrum of F region irregularities that is consistent with the one-dimensional spectra of density fluctuations observed by sounding rockets and with the axial ratio of irregularities determined recently. Normalized to data from one of the rocket flights on Kwajalein, the model predicts the 3-m scattering cross-section measured by CUPRI to within a few decibels. 55 refs., 12 figs.