Science.gov

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

    NASA Astrophysics Data System (ADS)

    Moller, D.; Hensley, S.; Wu, X.; Michel, T.; Muellerschoen, R.; Carswell, J.; Fisher, C.; Miller, T.; Milligan, L.; Sadowy, G.; Sanchez-Barbetty, M.; Lou, Y.

    2013-12-01

    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. 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 indicated swath widths over the ice between 5-7km, with height precisions ranging from 30cm-3m at a posting of 3m x 3m. Following the success of the IPY campaign, the Earth Science Techonology Office (ESTO) Airborne Innovative Technology Transition (AITT) program funded the upgrade of GLISTIN-A to a permanently-available pod-only system compatible with unpressurized operation. The AITT made three fundamental upgrades to improve system performance: 1. State-of-the-art solid-state power amplifiers (80W peak) were integrated directly on the antenna panel reducing front-end losses; 2. A ping-pong capability was incorporated to effectively double the baseline thereby improving height measurement precision by a factor of two; and 3. A high-fidelity calibration loop was implemented which is critical for routine processing. Upon completion of our engineering flights in February 2013, GLISTIN-A flew a brief campaign to Alaska (4/24-4/27/13). The purpose was to fully demonstrate GLISTIN-A's ability to generate high-precision, high resolution maps of ice surface topography with swaths in excess of 10km. Furthermore, the question of the utility of GLISTIN-A for sea-ice mapping, tracking and inventory has received a great deal of interest. To address this GLISTIN-A collected data over sea-ice in the Beaufort sea including an underflight of CryoSAT II. Note that there are ongoing activities to stage GLISTIN on the Global Hawk (GLISTIN-H) for which sea ice-mapping is a primary driver. Analysis of the data will focus on assessment of performance and interpretation over ice to include: 1. intercomparison of GLISTIN-A glacier height maps with lidar data and heritage SRTM DEM's for performance validation of GLISTIN-A over ice, 2. quantitative evaluation of mass change over the Columbia glacier via repeat observations made by GLISTIN-A with a 3 day separation, 3. assessment of GLISTIN-A's ability map sea ice extent, dynamics and possibly to measure freeboard.

  3. EcoSAR: NASA's P-band fully polarimetric single pass interferometric airborne radar

    NASA Astrophysics Data System (ADS)

    Osmanoglu, B.; Rincon, R. F.; Fatoyinbo, T. E.; Lee, S. K.; Sun, G.; Daniyan, O.; Harcum, M. E.

    2014-12-01

    EcoSAR is a new airborne synthetic aperture radar imaging system, developed at the NASA Goddard Space Flight Center. It is a P-band sensor that employs a non-conventional and innovative design. The EcoSAR system was designed as a multi-disciplinary instrument to image the 3-dimensional surface of the earth from a single pass platform with two antennas. EcoSAR's principal mission is to penetrate the forest canopy to return vital information about the canopy structure and estimate biomass. With a maximum bandwidth of 200 MHz in H and 120 MHz in V polarizations it can provide sub-meter resolution imagery of the study area. EcoSAR's dual antenna, 32 transmit and receive channel architecture provides a test-bed for developing new algorithms in InSAR data processing such as single pass interferometry, full polarimetry, post-processing synthesis of multiple beams, simultaneous measurement over both sides of the flight track, selectable resolution and variable incidence angle. The flexible architecture of EcoSAR will create new opportunities in radar remote sensing of forest biomass, permafrost active layer thickness, and topography mapping. EcoSAR's first test flight occurred between March 27th and April 1st, 2014 over the Andros Island in Bahamas and Corcovado and La Selva National Parks in Costa Rica. The 32 channel radar system collected about 6 TB of radar data in about 12 hours of data collection. Due to the existence of radio and TV communications in the operational frequency band, acquired data contains strong radar frequency interference, which had to be removed prior to beamforming and focusing. Precise locations of the antennas are tracked using high-rate GPS and inertial navigation units, which provide necessary information for accurate processing of the imagery. In this presentation we will present preliminary imagery collected during the test campaign, show examples of simultaneous dual track imaging, as well as a single pass interferogram. The interferometric product will be compared against existing DEMs for quality assessment.

  4. Information content of a single pass of phase-delay data from a short baseline connected element interferometer

    NASA Technical Reports Server (NTRS)

    Thurman, S. W.

    1990-01-01

    An analytic development of the information array obtained with a single tracking pass of phase-delay measurements made from a short baseline interferometer is presented. Phase-delay observations can be made with great precision from two antennas using a single, common distributed frequency standard, hence the name connected element. With the information array, closed-form expressions are developed for the error covariance in declination and right ascension. These equations serve as useful tools for analyzing the relative merits of candidate station locations for connected element interferometry (CEI). The navigation performance of a short baseline interferometer located at the Deep Space Network's (DSN's) Goldstone intracomplex is compared with that which is presently achievable using Very Long Baseline Interferometry (VLBI) over intercontinental baselines. The performance of an intracomplex pair of short baselines formed by three stations is also investigated, along with the use of a single baseline in conjunction with conventional two-way Doppler data. The phase-delay measurement accuracy and data rate used in the analysis are based on the expected performance of an experimental connected element system presently under construction at Goldstone. The results indicate that the VLBI system that will be used during the Galileo mission can determine the declination and right ascension of a distant spacecraft to an accuracy of 20 to 25 nrad, while the CEI triad system and the combination of CEI-Doppler system are both capable of 30 to 70 nrad performance.

  5. 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.

  6. TanDEM-X: A radar interferometer with two formation-flying satellites

    NASA Astrophysics Data System (ADS)

    Krieger, Gerhard; Zink, Manfred; Bachmann, Markus; Bräutigam, Benjamin; Schulze, Daniel; Martone, Michele; Rizzoli, Paola; Steinbrecher, Ulrich; Walter Antony, John; De Zan, Francesco; Hajnsek, Irena; Papathanassiou, Kostas; Kugler, Florian; Rodriguez Cassola, Marc; Younis, Marwan; Baumgartner, Stefan; López-Dekker, Paco; Prats, Pau; Moreira, Alberto

    2013-08-01

    TanDEM-X (TerraSAR-X add-on for Digital Elevation Measurements) is an innovative formation-flying radar mission that opens a new era in spaceborne radar remote sensing. The primary objective is the acquisition of a global digital elevation model (DEM) with unprecedented accuracy (12 m horizontal resolution and 2 m relative height accuracy). This goal is achieved by extending the TerraSAR-X synthetic aperture radar (SAR) mission by a second, TerraSAR-X like satellite (TDX) flying in close formation with TerraSAR-X (TSX). Both satellites form together a large single-pass SAR interferometer with the opportunity for flexible baseline selection. This enables the acquisition of highly accurate cross-track interferograms without the inherent accuracy limitations imposed by repeat-pass interferometry due to temporal decorrelation and atmospheric disturbances. Besides the primary goal of the mission, several secondary mission objectives based on along-track interferometry as well as new bistatic and multistatic SAR techniques have been defined, representing an important and innovative asset of the TanDEM-X mission. TanDEM-X is implemented in the framework of a public-private partnership between the German Aerospace Center (DLR) and EADS Astrium GmbH. The TanDEM-X satellite was successfully launched in June 2010 and the mission started its operational data acquisition in December 2010. This paper provides an overview of the TanDEM-X mission and summarizes its actual status and performance. Furthermore, results from several scientific radar experiments are presented that show the great potential of future formation-flying interferometric SAR missions to serve novel remote sensing applications.

  7. Radar Interferometer for Topographic Mapping of Glaciers and Ice Sheets

    NASA Technical Reports Server (NTRS)

    Moller, Delwyn K.; Sadowy, Gregory A.; Rignot, Eric J.; Madsen, Soren N.

    2007-01-01

    A report discusses Ka-band (35-GHz) radar for mapping the surface topography of glaciers and ice sheets at high spatial resolution and high vertical accuracy, independent of cloud cover, with a swath-width of 70 km. The system is a single- pass, single-platform interferometric synthetic aperture radar (InSAR) with an 8-mm wavelength, which minimizes snow penetration while remaining relatively impervious to atmospheric attenuation. As exhibited by the lower frequency SRTM (Shuttle Radar Topography Mission) AirSAR and GeoSAR systems, an InSAR measures topography using two antennas separated by a baseline in the cross-track direction, to view the same region on the ground. The interferometric combination of data received allows the system to resolve the pathlength difference from the illuminated area to the antennas to a fraction of a wavelength. From the interferometric phase, the height of the target area can be estimated. This means an InSAR system is capable of providing not only the position of each image point in along-track and slant range as with a traditional SAR but also the height of that point through interferometry. Although the evolution of InSAR to a millimeter-wave center frequency maximizes the interferometric accuracy from a given baseline length, the high frequency also creates a fundamental problem of swath coverage versus signal-to-noise ratio. While the length of SAR antennas is typically fixed by mass and stowage or deployment constraints, the width is constrained by the desired illuminated swath width. As the across-track beam width which sets the swath size is proportional to the wavelength, a fixed swath size equates to a smaller antenna as the frequency is increased. This loss of antenna size reduces the two-way antenna gain to the second power, drastically reducing the signal-to-noise ratio of the SAR system. This fundamental constraint of high-frequency SAR systems is addressed by applying digital beam-forming (DBF) techniques to synthesize multiple simultaneous receive beams in elevation while maintaining a broad transmit illumination. Through this technique, a high antenna gain on receive is preserved, thereby reducing the required transmit power and thus enabling high-frequency SARs and high-precision InSAR from a single spacecraft.

  8. Multifrequency, single pass free electron laser

    DOEpatents

    Szoke, Abraham (Fremont, CA); Prosnitz, Donald (Walnut Creek, CA)

    1985-01-01

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

  9. The altitude of type 3 auroral irregularities: Radar interferometer observations and implications

    SciTech Connect

    Sahr, J.D.; Farley, D.T.; Swartz, W.E. ); Providakes, J.F. )

    1991-10-01

    VHF coherent scatter radars at auroral latitudes have observed scatterers with narrow power spectra at sub-ion acoustic mean Doppler shifts. These spectra have been designated type 3. The mean Doppler shift of these waves is often near the atomic (O{sup +}) or, less frequently, the molecular (O{sub 2}{sup +} and NO{sup +}) gyro frequencies. These type 3 echoes have been attributed to an electrostatic ion-cyclotron (EIC) instability in the upper E region (h > 140 km), where the ion collision frequency becomes low enough to permit ion gyromotion. Interferometric analysis of recent coherent radar observations with the CUPRI (Cornell University portable radar interferometer) shows that type 3 events occur at typical electrojet altitudes (100-120 km), however. At these altitudes the ion collision frequency is greater than the ion gyrofrequency and there can be no cyclotron motion. The cause of the observed type 3 echoes hence remains a mystery.

  10. Dilution in single pass arc welds

    SciTech Connect

    DuPont, J.N.; Marder, A.R.

    1996-06-01

    A study was conducted on dilution of single pass arc welds of type 308 stainless steel filler metal deposited onto A36 carbon steel by the plasma arc welding (PAW), gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and submerged arc welding (SAW) processes. Knowledge of the arc and melting efficiency was used in a simple energy balance to develop an expression for dilution as a function of welding variables and thermophysical properties of the filler metal and substrate. Comparison of calculated and experimentally determined dilution values shows the approach provides reasonable predictions of dilution when the melting efficiency can be accurately predicted. The conditions under which such accuracy is obtained are discussed. A diagram is developed from the dilution equation which readily reveals the effect of processing parameters on dilution to aid in parameter optimization.

  11. Auroral ion acoustic wave enhancement observed with a radar interferometer system

    NASA Astrophysics Data System (ADS)

    Schlatter, N. M.; Belyey, V.; Gustavsson, B.; Ivchenko, N.; Whiter, D.; Dahlgren, H.; Tuttle, S.; Grydeland, T.

    2015-07-01

    Measurements of naturally enhanced ion acoustic line (NEIAL) echoes obtained with a five-antenna interferometric imaging radar system are presented. The observations were conducted with the European Incoherent SCATter (EISCAT) radar on Svalbard and the EISCAT Aperture Synthesis Imaging receivers (EASI) installed at the radar site. Four baselines of the interferometer are used in the analysis. Based on the coherence estimates derived from the measurements, we show that the enhanced backscattering region is of limited extent in the plane perpendicular to the geomagnetic field. Previously it has been argued that the enhanced backscatter region is limited in size; however, here the first unambiguous observations are presented. The size of the enhanced backscatter region is determined to be less than 900 × 500 m, and at times less than 160 m in the direction of the longest antenna separation, assuming the scattering region to have a Gaussian scattering cross section in the plane perpendicular to the geomagnetic field. Using aperture synthesis imaging methods volumetric images of the NEIAL echo are obtained showing the enhanced backscattering region to be aligned with the geomagnetic field. Although optical auroral emissions are observed outside the radar look direction, our observations are consistent with the NEIAL echo occurring on field lines with particle precipitation.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  13. Single Pass Multi-component Harvester

    SciTech Connect

    Reed Hoskinson; J. Richard Hess

    2004-08-01

    Abstract. In order to meet the U. S. government’s goal of supplementing the energy available from petroleum by increasing the production of energy from renewable resources, increased production of bioenergy has become one of the new goals of the United States government and our society. U.S. Executive Orders and new Federal Legislation have mandated changes in government procedures and caused reorganizations within the government to support these goals. The Biomass Research and Development Initiative is a multi-agency effort to coordinate and accelerate all U.S. Federal biobased products and bioenergy research and development. The Initiative is managed by the National Biomass Coordination Office, which is staffed by both the DOE and the USDA. One of the most readily available sources of biomass from which to produce bioenergy is an agricultural crop residue, of which straw from small grains is the most feasible residue with which to start. For the straw residue to be used its collection must be energy efficient and its removal must not impact the sustainability of the growing environment. In addition, its collection must be economically advantageous to the producer. To do all that, a single pass multi-component harvester system is most desirable. Results from our first prototype suggest that current combines probably do adequate threshing and that a separate chassis can be developed that does additional separation and that is economically feasible.

  14. The Single Pass Multi-component Harvester

    SciTech Connect

    Reed Hoskinson; John R. Hess

    2004-08-01

    The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the official position of the American Society of Agricultural Engineers (ASAE), and its printing and distribution does not constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by ASAE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ASAE meeting paper. EXAMPLE: Author's Last Name, Initials. 2004. Title of Presentation. ASAE Paper No. 04xxxx. St. Joseph, Mich.: ASAE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASAE at hq@asae.org or 269-429-0300 (2950 Niles Road, St. Joseph, MI 49085-9659 USA). Abstract. In order to meet the U. S. government’s goal of supplementing the energy available from petroleum by increasing the production of energy from renewable resources, increased production of bioenergy has become one of the new goals of the United States government and our society. U.S. Executive Orders and new Federal Legislation have mandated changes in government procedures and caused reorganizations within the government to support these goals. The Biomass Research and Development Initiative is a multi-agency effort to coordinate and accelerate all U.S. Federal biobased products and bioenergy research and development. The Initiative is managed by the National Biomass Coordination Office, which is staffed by both the DOE and the USDA. One of the most readily available sources of biomass from which to produce bioenergy is an agricultural crop residue, of which straw from small grains is the most feasible residue with which to start. For the straw residue to be used its collection must be energy efficient and its removal must not impact the sustainability of the growing environment. In addition, its collection must be economically advantageous to the producer. To do all that, a single pass multi-component harvester system is most desirable. Results from our first prototype suggest that current combines probably do adequate threshing and that a separate chassis can be developed that does additional separation and that is economically feasible.

  15. Thermal efficiency of single-pass solar air collector

    SciTech Connect

    Ibrahim, Zamry; Ibarahim, Zahari; Yatim, Baharudin; Ruslan, Mohd Hafidz

    2013-11-27

    Efficiency of a finned single-pass solar air collector was studied. This paper presents the experimental study to investigate the effect of solar radiation and mass flow rate on efficiency. The fins attached at the back of absorbing plate to improve the thermal efficiency of the system. The results show that the efficiency is increased proportional to solar radiation and mass flow rate. Efficiency of the collector archived steady state when reach to certain value or can be said the maximum performance.

  16. The Shuttle Radar Topography Mission

    NASA Technical Reports Server (NTRS)

    Farr, Tom G.; Kobrick, Mike

    2000-01-01

    On February 22, 2000 Space Shuttle Endeavour landed at Kennedy Space Center, completing the highly successful 11-day flight of the Shuttle Radar Topography Mission (SRTM). Onboard were over 300 high-density tapes containing data for the highest resolution, most complete digital topographic map of Earth ever made. SRTM is a cooperative project between NASA and the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense. The mission was designed to use a single-pass radar interferometer to produce a digital elevation model (DEM) of the Earth's land surface between about 60 deg north and 56 deg south latitude. When completed, the DEM will have 30 m pixel spacing and about 15 m vertical accuracy. Two orthorectified image mosaics (one from the ascending passes with illumination from the southeast and one from descending passes with illumination from the southwest) will also be produced.

  17. Comparison of medium frequency pulsed radar interferometer and correlation analysis winds, part 1

    NASA Technical Reports Server (NTRS)

    Meek, C. E.; Reid, I. M.; Manson, A. H.

    1986-01-01

    In principle, the interferometer analysis determines the radial velocity and direction of single scatterers provided that each has a sufficiently different Doppler frequency to permit separation by spectral analysis. In fact, scatterers will not have constant radial velocity, and their Doppler frequencies as well as their directions will be modulated by their horizontal motion. Thus, there is a tradeoff between the poorer resolution but less smeared scatterers on shorter records and the higher resolution (longer) records. Three or more non-collinear scatterers are sufficient to determine the wind. It appears that the velocity found from the combined interferometer peaks agrees well with the apparent velocity from correlation methods, but the true velocity is a factor of 2 smaller. This difference might be resolved by searching for scatters showing regular movement between adjacent records.

  18. Comparison of medium frequency pulsed radar interferometer and correlation analysis winds, part 2

    NASA Technical Reports Server (NTRS)

    Meek, C. E.; Reid, I. M.; Manson, A. H.

    1986-01-01

    In order to test whether the chosen Doppler peaks represent localized scatters in motion, as opposed to some sort of integrated composite, an attempt was made to determine the change in position of single scatterers over a series of sequential records. A four-antenna system was employed which had 1 degree of freedom in phase. Due to limitations N-S linear transmission and E-W linear reception were used. The Doppler frequency peak selection criteria were that at least two of the four power spectra should have a local peak, and that normalized phase discrepancy, should be less than 0.3. The lack of success in tracking individual scatters seems to suggest a short lifetime. If this is the case, then the present experiment is not able to resolve the difference found between the correlation analysis true velocity and the interferometer value. On the other hand, it appears that the interferometer may be of some use in tracking waves.

  19. Observations of storm time midlatitude ion-neutral coupling using SuperDARN radars and NATION Fabry-Perot interferometers

    NASA Astrophysics Data System (ADS)

    Joshi, P. P.; H. Baker, J. B.; Ruohoniemi, J. M.; Makela, J. J.; Fisher, D. J.; Harding, B. J.; Frissell, N. A.; Thomas, E. G.

    2015-10-01

    Ion drag is known to play an important role in driving neutral thermosphere circulation at auroral latitudes, especially during the main phase of geomagnetic storms. During the recovery phase, the neutrals are known to drive the ions and generate ionospheric electric fields and currents via the disturbance dynamo mechanism. At midlatitudes, the precise interplay between ions and neutrals is less understood largely because of the paucity of measurements that have been available. In this work, we investigate ion-neutral coupling at middle latitudes using colocated ion drift velocity measurements obtained from Super Dual Auroral Radar Network radars and neutral wind velocity and temperature measurements obtained from the North American Thermosphere Ionosphere Observing Network (NATION) Fabry-Perot interferometers. We examine one recent storm period on 2-3 October 2013 during both the main phase and late recovery phase. By using ion-neutral momentum exchange theory and a time-lagged correlation analysis, we analyze the coupling time scales and dominant driving mechanisms. We observe that during the main phase the neutrals respond to the ion convection on a time scale of ˜84 min which is significantly faster than what would be expected from local ion drag momentum forcing alone. This suggests that other storm time influences are important for driving the neutrals during the main phase, such as Joule heating. During the late recovery phase, the neutrals are observed to drive the ion convection without any significant time delay, consistent with the so-called "neutral fly wheel effect" or disturbance dynamo persisting well into the late recovery phase.

  20. Error Analysis for High Resolution Topography with Bi-Static Single-Pass SAR Interferometry

    NASA Technical Reports Server (NTRS)

    Muellerschoen, Ronald J.; Chen, Curtis W.; Hensley, Scott; Rodriguez, Ernesto

    2006-01-01

    We present a flow down error analysis from the radar system to topographic height errors for bi-static single pass SAR interferometry for a satellite tandem pair. Because of orbital dynamics the baseline length and baseline orientation evolve spatially and temporally, the height accuracy of the system is modeled as a function of the spacecraft position and ground location. Vector sensitivity equations of height and the planar error components due to metrology, media effects, and radar system errors are derived and evaluated globally for a baseline mission. Included in the model are terrain effects that contribute to layover and shadow and slope effects on height errors. The analysis also accounts for nonoverlapping spectra and the non-overlapping bandwidth due to differences between the two platforms' viewing geometries. The model is applied to a 514 km altitude 97.4 degree inclination tandem satellite mission with a 300 m baseline separation and X-band SAR. Results from our model indicate that global DTED level 3 can be achieved.

  1. Nonlinear Effects in Single-Pass ICRF Heating

    NASA Technical Reports Server (NTRS)

    Arefiev, A. V.; Breizman, B. N.

    1999-01-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) concept employs Ion Cyclotron Resonant Frequency (ICRF) heating as the main power deposition mechanism. Since the ions accelerate to the full energy in a single pass through the cyclotron resonance, their response to the RF-field will be essentially nonlinear - hence the motivation to amend the commonly used linear approach to the problem. In a collisionless plasma, the energy gain of an accelerated ion is limited by the time the particle spends at the resonance. This time is affected by: (1) incident flow velocity, (2) longitudinal grad B force, (3) ambipolar electric field, and (4) ponderomotive force of the RF-field. Our analysis shows that the grad B force is the dominant factor at low to moderate levels of RF-power. We present nonlinear scaling for the energy gain and the absorption efficiency with RF-power and plasma parameters. We also demonstrate that the nonlinear regime exhibits a steep decrease in the plasma density at the resonance.

  2. The E-Region Wind Interferometer (ERWIN): Description of the Least Mean Squares Data Analysis Routine, Wind Results, and Comparisons with the Meteor Radar

    NASA Astrophysics Data System (ADS)

    Kristoffersen, Samuel Kaare

    The E-Region Wind Interferometer (ERWIN) is a Michelson interferometer which observes mesospheric winds using Doppler shifts in three airglow emissions (atomic oxygen, molecular oxygen, and hydroxyl). Innovations include a quad mirror and a CCD detector which allow simultaneous observation of winds in four directions and the vertical. A measurement cadence of ~ 3 minutes for all the airglow emissions and directions with an accuracy of ~2m/sis achieved. This is the highest temporal resolution for accurate mesospheric winds in the world, providing the possibility for the first vertical wind measurements in airglow to be achieved. Data analysis algorithms and procedures are developed for this instrument including a Levenberg-Marquardt technique, and a bin-by-bin analysis routine. Interesting geophysical phenomena including a large semidiurnal tide, and significant airglow intensity variations were observed during a sudden stratospheric warming. Comparisons with a meteor radar validate both instruments, and allow the determination of airglow layer heights.

  3. Fine Resolution Topographic Mapping of the Jovian Moons: A Ka-Band High Resolution Topographic Mapping Interferometric Synthetic Aperture Radar

    NASA Technical Reports Server (NTRS)

    Madsen, S. N.; Carsey, F. D.; Turtle, E. P.

    2003-01-01

    The topographic data set obtained by MOLA has provided an unprecedented level of information about Mars' geologic features. The proposed flight of JIMO provides an opportunity to accomplish a similar mapping of and comparable scientific discovery for the Jovian moons through use of an interferometric imaging radar analogous to the Shuttle radar that recently generated a new topographic map of Earth. A Ka-band single pass across-track synthetic aperture radar (SAR) interferometer can provide very high resolution surface elevation maps. The concept would use two antennas mounted at the ends of a deployable boom (similar to the Shuttle Radar Topographic Mapper) extended orthogonal to the direction of flight. Assuming an orbit altitude of approximately 100km and a ground velocity of approximately 1.5 km/sec, horizontal resolutions at the 10 meter level and vertical resolutions at the sub-meter level are possible.

  4. Fine resolution topographic mapping of the Jovian moons: a Ka-band high resolution topographic mapping interferometric synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Madsen, Soren N.; Carsey, Frank D.; Turtle, Elizabeth P.

    2003-01-01

    The topographic data set obtained by MOLA has provided an unprecedented level of information about Mars' geologic features. The proposed flight of JIMO provides an opportunity to accomplish a similar mapping of and comparable scientific discovery for the Jovian moons through us of an interferometric imaging radar analogous to the Shuttle radar that recently generated a new topographic map of Earth. A Ka-band single pass across-track synthetic aperture radar (SAR) interferometer can provide very high resolution surface elevation maps. The concept would use two antennas mounted at the ends of a deployable boom (similar to the Shuttle Radar Topographic Mapper) extended orthogonal to the direction of flight. Assuming an orbit altitude of approximately 100 km and a ground velocity of approximately 1.5 km/sec, horizontal resolutions at the 10 meter level and vertical resolutions at the sub-meter level are possible.

  5. 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.

  6. 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.

  7. Global Identification of Protein Post-translational Modifications in a Single-Pass Database Search

    PubMed Central

    2015-01-01

    Bottom-up proteomics database search algorithms used for peptide identification cannot comprehensively identify post-translational modifications (PTMs) in a single-pass because of high false discovery rates (FDRs). A new approach to database searching enables global PTM (G-PTM) identification by exclusively looking for curated PTMs, thereby avoiding the FDR penalty experienced during conventional variable modification searches. We identified over 2200 unique, high-confidence modified peptides comprising 26 different PTM types in a single-pass database search. PMID:26418581

  8. 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.

  9. Evaluating single-pass catch as a tool for identifying spatial pattern in fish distribution

    USGS Publications Warehouse

    Bateman, D.S.; Gresswell, R.E.; Torgersen, C.E.

    2005-01-01

    We evaluate the efficacy of single-pass electrofishing without blocknets as a tool for collecting spatially continuous fish distribution data in headwater streams. We compare spatial patterns in abundance, sampling effort, and length-frequency distributions from single-pass sampling of coastal cutthroat trout (Oncorhynchus clarki clarki) to data obtained from a more precise multiple-pass removal electrofishing method in two mid-sized (500-1000 ha) forested watersheds in western Oregon. Abundance estimates from single- and multiple-pass removal electrofishing were positively correlated in both watersheds, r = 0.99 and 0.86. There were no significant trends in capture probabilities at the watershed scale (P > 0.05). Moreover, among-sample variation in fish abundance was higher than within-sample error in both streams indicating that increased precision of unit-scale abundance estimates would provide less information on patterns of abundance than increasing the fraction of habitat units sampled. In the two watersheds, respectively, single-pass electrofishing captured 78 and 74% of the estimated population of cutthroat trout with 7 and 10% of the effort. At the scale of intermediate-sized watersheds, single-pass electrofishing exhibited a sufficient level of precision to be effective in detecting spatial patterns of cutthroat trout abundance and may be a useful tool for providing the context for investigating fish-habitat relationships at multiple scales.

  10. 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.

  11. 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.

  12. Performance evaluation of pyrochlore ceramic waste forms by single pass flow through testing

    NASA Astrophysics Data System (ADS)

    Zhao, P.; Bourcier, W. L.; Esser, B. K.; Shaw, H. F.

    2000-07-01

    Titanate-based ceramic waste forms for the disposal of nuclear wastes have been the subjects of numerous studies over the past decades. In order to assess the performance of this ceramic in a potential Yucca Mountain high-level waste (HLW) repository, it is necessary to understand the kinetics and mechanisms of corrosion of the ceramic under repository conditions. To this end, we are conducting single pass flow-through (SPFT) dissolution tests on ceramics relevant to Pu disposition.

  13. 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.

  14. Assessing the efficacy of single-pass backpack electrofishing to characterize fish community structure

    USGS Publications Warehouse

    Meador, M.R.; McIntyre, J.P.; Pollock, K.H.

    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 richness from first-pass sampling (p??s1) ranged from 80.7% to 100% of estimated total species richness for each river basin, based on at least seven samples per basin. However, p??s1 values for individual sites ranged from 40% to 100% of estimated total species richness. Additional species unique to the second pass were collected in 50.3% of the samples. Of these, cyprinids and centrarchids were collected most frequently. Proportional fish species richness estimated for the first pass increased significantly with decreasing stream width for 1 of the 10 river basins. When used to calculate probabilities of detection of individual fish species, the removal model failed 48% of the time because the number of individuals of a species was greater in the second pass than in the first pass. Single-pass backpack electrofishing data alone may make it difficult to determine whether characterized fish community structure data are real or spurious. The two-pass removal model can be used to assess the effectiveness of sampling species richness with a single electrofishing pass. However, the two-pass removal model may have limited utility to determine probabilities of detection of individual species and, thus, limit the ability to assess the effectiveness of single-pass sampling to characterize species relative abundances. Multiple-pass (at least three passes) backpack electrofishing at a large number of sites may not be cost-effective as part of a standardized sampling protocol for large-geographic-scale studies. However, multiple-pass electrofishing at some sites may be necessary to better evaluate the adequacy of single-pass electrofishing and to help make meaningful interpretations of fish community structure.

  15. Observations of single-pass ion cyclotron heating in a trans-sonic flowing plasma

    NASA Astrophysics Data System (ADS)

    Bering, E. A.; Díaz, F. R. Chang; Squire, J. P.; Glover, T. W.; Carter, M. D.; McCaskill, G. E.; Longmier, B. W.; Brukardt, M. S.; Chancery, W. J.; Jacobson, V. T.

    2010-04-01

    The VAriable Specific Impulse Magnetoplasma Rocket (VASIMR®) is a high power electric spacecraft propulsion system, capable of Isp/thrust modulation at constant power [F. R. Chang Díaz et al., Proceedings of the 39th AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, 8-11 Jan. 2001]. The VASIMR® uses a helicon discharge to generate plasma. This plasma is energized by an rf booster stage that uses left hand polarized slow mode waves launched from the high field side of the ion cyclotron resonance. In the experiments reported in this paper, the booster uses 2-4 MHz waves with up to 50 kW of power. This process is similar to the ion cyclotron heating (ICH) in tokamaks, but in the VASIMR® the ions only pass through the resonance region once. The rapid absorption of ion cyclotron waves has been predicted in recent theoretical studies. These theoretical predictions have been supported with several independent measurements in this paper. The single-pass ICH produced a substantial increase in ion velocity. Pitch angle distribution studies showed that this increase took place in the resonance region where the ion cyclotron frequency was roughly equal to the frequency on the injected rf waves. Downstream of the resonance region the perpendicular velocity boost should be converted to axial flow velocity through the conservation of the first adiabatic invariant as the magnetic field decreases in the exhaust region of the VASIMR®. This paper will review all of the single-pass ICH ion acceleration data obtained using deuterium in the first VASIMR® physics demonstrator machine, the VX-50. During these experiments, the available power to the helicon ionization stage increased from 3 to 20+ kW. The increased plasma density produced increased plasma loading of the ICH coupler. Starting with an initial demonstration of single-pass ion cyclotron acceleration, the experiments demonstrate significant improvements in coupler efficiency and in ion heating efficiency. In deuterium plasma, ≥80% efficient absorption of 20 kW of ICH input power was achieved. No clear evidence for power limiting instabilities in the exhaust beam has been observed.

  16. Improved reduced models for single-pass and reflective semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    O Duill, S. P.; Barry, L. P.

    2015-01-01

    We present highly accurate and easy to implement, improved lumped semiconductor optical amplifier (SOA) models for both single-pass and reflective semiconductor optical amplifiers (RSOA). The key feature of the model is the inclusion of the internal losses and we show that a few SOA subdivisions are required to achieve a computational accuracy of <0.12 dB. For the case of RSOAs, we generalize a recently published model to account for the internal losses that are vital to replicate the observed RSOA behavior. The results of the improved reduced RSOA model show large overlap when compared to a full bidirectional travelling wave model for over a 40 dB dynamic range of input powers and a 20 dB dynamic range of reflectivity values. The models would be useful for the rapid system simulation of signals in communication systems, i.e. passive optical networks that employ RSOAs, signal processing using SOAs.

  17. AN EXPERIMENTAL TEST OF SUPERRADIANCE IN A SINGLE PASS SEEDED FEL.

    SciTech Connect

    WATANABE, T.; LIU, D.; MURPHY, J.B.; ROSE, J.; SHAFTAN, T.; TSANG, T.; WANG, X.J.; YU, L.H.

    2005-08-21

    Superradiance and nonlinear evolution of a FEL pulse in a single-pass FEL were experimentally demonstrated at the National Synchrotron Light Source (NSLS) Source Development Laboratory (SDL). The experiment was performed using a 1.5 ps high-brightness electron beam and a 100fs Ti:Sapphire seed laser. The seed laser and electron beam interact in the 10 meter long NISUS undulator with a period of 3.89 cm. The FEL spectrum, energy and pulse length along the undulator were measured. FEL saturation was observed, and gain of more the 200 (relative to seed laser) was measured. Both FEL spectrum widening and pulse length shortening were observed; FEL pulses as short as 65 fs FWHM were measured. The superradiance and nonlinear evolution were also simulated using the numerical code GENESIS1.3 yielding good agreement with the experimental results.

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

    SciTech Connect

    Biagini, M.E.; Raimondi, P.; Seeman, J.; 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.

  19. 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.

  20. Augmented Binary Substitution: Single-pass CDR germ-lining and stabilization of therapeutic antibodies.

    PubMed

    Townsend, Sue; Fennell, Brian J; Apgar, James R; Lambert, Matthew; McDonnell, Barry; Grant, Joanne; Wade, Jason; Franklin, Edward; Foy, Niall; Ní Shúilleabháin, Deirdre; Fields, Conor; Darmanin-Sheehan, Alfredo; King, Amy; Paulsen, Janet E; Hickling, Timothy P; Tchistiakova, Lioudmila; Cunningham, Orla; Finlay, William J J

    2015-12-15

    Although humanized antibodies have been highly successful in the clinic, all current humanization techniques have potential limitations, such as: reliance on rodent hosts, immunogenicity due to high non-germ-line amino acid content, v-domain destabilization, expression and formulation issues. This study presents a technology that generates stable, soluble, ultrahumanized antibodies via single-step complementarity-determining region (CDR) germ-lining. For three antibodies from three separate key immune host species, binary substitution CDR cassettes were inserted into preferred human frameworks to form libraries in which only the parental or human germ-line destination residue was encoded at each position. The CDR-H3 in each case was also augmented with 1 ± 1 random substitution per clone. Each library was then screened for clones with restored antigen binding capacity. Lead ultrahumanized clones demonstrated high stability, with affinity and specificity equivalent to, or better than, the parental IgG. Critically, this was mainly achieved on germ-line frameworks by simultaneously subtracting up to 19 redundant non-germ-line residues in the CDRs. This process significantly lowered non-germ-line sequence content, minimized immunogenicity risk in the final molecules and provided a heat map for the essential non-germ-line CDR residue content of each antibody. The ABS technology therefore fully optimizes the clinical potential of antibodies from rodents and alternative immune hosts, rendering them indistinguishable from fully human in a simple, single-pass process. PMID:26621728

  1. 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.

  2. Packaging design criteria for the N Reactor/single pass reactor fuel characterization shipments

    SciTech Connect

    Stevens, P.F.

    1994-08-31

    The majority of the spent fuel from the N Reactor and the single pass reactors (SPR) is presently being stored at the basins in the 100 K Area. Characterization of these fuels is essential to formulate a safe and efficient processing/disposal method for the spent fuel. Consequently, it is necessary to transport a cross section of spent fuel from the K Basins to the hot cells at the 327 Building in the 300 Area for analysis. The CNS 1-13G cask, a US Nuclear Regulatory Commission (NRC) certified cask manufactured by the ChemNuclear company, will be utilized for the transportation for irradiated fuel elements from the K Basins to the 327 Laboratories for characterization. The cask will utilize an inner container to compensate for the possibility of failed fuel cladding and to reduce the chances of contaminating the cask or the off loading facility. The Packaging Design Criteria (PDC) for these shipments establishes the acceptance criteria for the cask and for the design of an inner container that will be used in the Safety Evaluation for Packaging (SEP).

  3. Double-Sided Single-Pass Submerged Arc Welding for 2205 Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Luo, Jian; Yuan, Yi; Wang, Xiaoming; Yao, Zongxiang

    2013-09-01

    The duplex stainless steel (DSS), which combines the characteristics of ferritic steel and austenitic steel, is used widely. The submerged arc welding (SAW) method is usually applied to join thick plates of DSS. However, an effective welding procedure is needed in order to obtain ideal DSS welds with an appropriate proportion of ferrite (?) and austenite (?) in the weld zone, particularly in the melted zone and heat-affected zone. This study evaluated the effectiveness of a high efficiency double-sided single-pass (DSSP) SAW joining method for thick DSS plates. The effectiveness of the converse welding procedure, characterizations of weld zone, and mechanical properties of welded joint are analyzed. The results show an increasing appearance and continuous distribution feature of the ? phase in the fusion zone of the leading welded seam. The converse welding procedure promotes the ? phase to precipitate in the fusion zone of leading welded side. The microhardness appears to significantly increase in the center of leading welded side. Ductile fracture mode is observed in the weld zone. A mixture fracture feature appears with a shear lip and tears in the fusion zone near the fusion line. The ductility, plasticity, and microhardness of the joints have a significant relationship with ? phase and heat treatment effect influenced by the converse welding step. An available heat input controlling technology of the DSSP formation method is discussed for SAW of thick DSS plates.

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

    SciTech Connect

    Choudhary, Shashank E-mail: mohantejesh93@gmail.com E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Tejesh, Chiruvolu Mohan E-mail: mohantejesh93@gmail.com E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Regalla, Srinivasa Prakash E-mail: mohantejesh93@gmail.com E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Suresh, Kurra E-mail: mohantejesh93@gmail.com E-mail: ksuresh@hyderabad.bits-pilani.ac.in

    2013-12-16

    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.

  5. Augmented Binary Substitution: Single-pass CDR germ-lining and stabilization of therapeutic antibodies

    PubMed Central

    Townsend, Sue; Fennell, Brian J.; Apgar, James R.; Lambert, Matthew; McDonnell, Barry; Grant, Joanne; Wade, Jason; Franklin, Edward; Foy, Niall; Ní Shúilleabháin, Deirdre; Fields, Conor; Darmanin-Sheehan, Alfredo; King, Amy; Paulsen, Janet E.; Tchistiakova, Lioudmila; Cunningham, Orla; Finlay, William J. J.

    2015-01-01

    Although humanized antibodies have been highly successful in the clinic, all current humanization techniques have potential limitations, such as: reliance on rodent hosts, immunogenicity due to high non-germ-line amino acid content, v-domain destabilization, expression and formulation issues. This study presents a technology that generates stable, soluble, ultrahumanized antibodies via single-step complementarity-determining region (CDR) germ-lining. For three antibodies from three separate key immune host species, binary substitution CDR cassettes were inserted into preferred human frameworks to form libraries in which only the parental or human germ-line destination residue was encoded at each position. The CDR-H3 in each case was also augmented with 1 ± 1 random substitution per clone. Each library was then screened for clones with restored antigen binding capacity. Lead ultrahumanized clones demonstrated high stability, with affinity and specificity equivalent to, or better than, the parental IgG. Critically, this was mainly achieved on germ-line frameworks by simultaneously subtracting up to 19 redundant non-germ-line residues in the CDRs. This process significantly lowered non-germ-line sequence content, minimized immunogenicity risk in the final molecules and provided a heat map for the essential non-germ-line CDR residue content of each antibody. The ABS technology therefore fully optimizes the clinical potential of antibodies from rodents and alternative immune hosts, rendering them indistinguishable from fully human in a simple, single-pass process. PMID:26621728

  6. Mechanics of single pass equal channel angular extrusion of powder in tubes

    NASA Astrophysics Data System (ADS)

    Nagasekhar, A. V.; Tick-Hon, Y.; Ramakanth, K. S.

    2006-11-01

    In the current study powder in tubes (PITs) are processed through single pass equal channel angular extrusion (ECAE), for two different powders by using three different tube materials. Studies were conducted for the first time to understand the processing mechanism of ECAE of PITs. In the case of hard brittle intermetallic magnesium boride (MgB2) powder, the process was found to primarily involve compaction and shear-sliding of the powder, and localized-deformation of the tube. Reasons for localized-deformation occurring during ECAE were discussed in detail. Compaction efficiency was understood to depend not only on the material of the tube but also on the homogeneity of stress and strain in the composite PIT. Various frictional stresses and mechanisms of localized-deformation were found to be the reasons for stress-strain inhomogeneity. In the case of copper powder, even though localized-deformation occurred, higher inter-particle friction and low yield strength of the powder helped in the complete densification of the powders.

  7. Intestinal permeability of forskolin by in situ single pass perfusion in rats.

    PubMed

    Liu, Zhen-Jun; Jiang, Dong-bo; Tian, Lu-Lu; Yin, Jia-Jun; Huang, Jian-Ming; Weng, Wei-Yu

    2012-05-01

    The intestinal permeability of forskolin was investigated using a single pass intestinal perfusion (SPIP) technique in rats. SPIP was performed in different intestinal segments (duodenum, jejunum, ileum, and colon) with three concentrations of forskolin (11.90, 29.75, and 59.90 µg/mL). The investigations of adsorption and stability were performed to ensure that the disappearance of forskolin from the perfusate was due to intestinal absorption. The results of the SPIP study indicated that forskolin could be absorbed in all segments of the intestine. The effective permeability (P (eff)) of forskolin was in the range of drugs with high intestinal permeability. The P (eff) was highest in the duodenum as compared to other intestinal segments. The decreases of P (eff) in the duodenum and ileum at the highest forskolin concentration suggested a saturable transport process. The addition of verapamil, a P-glycoprotein inhibitor, significantly enhanced the permeability of forskolin across the rat jejunum. The absorbed fraction of dissolved forskolin after oral administration in humans was estimated to be 100 % calculated from rat P (eff). In conclusion, dissolved forskolin can be absorbed readily in the intestine. The low aqueous solubility of forskolin might be a crucial factor for its poor oral bioavailability. PMID:22411728

  8. Non-destructive single-pass low-noise detection of ions in a beamline.

    PubMed

    Schmidt, Stefan; Murböck, Tobias; Andelkovic, Zoran; Birkl, Gerhard; Nörtershäuser, Wilfried; Stahl, Stefan; Vogel, Manuel

    2015-11-01

    We have conceived, built, and operated a device for the non-destructive single-pass detection of charged particles in a beamline. The detector is based on the non-resonant pick-up and subsequent low-noise amplification of the image charges induced in a cylindrical electrode surrounding the particles' beam path. The first stage of the amplification electronics is designed to be operated from room temperature down to liquid helium temperature. The device represents a non-destructive charge counter as well as a sensitive timing circuit. We present the concept and design details of the device. We have characterized its performance and show measurements with low-energy highly charged ions (such as Ar(13+)) passing through one of the electrodes of a cylindrical Penning trap. This work demonstrates a novel approach of non-destructive, low noise detection of charged particles which is, depending on the bunch structure, suitable, e.g., for ion traps, low-energy beamlines or accelerator transfer sections. PMID:26628124

  9. Non-destructive single-pass low-noise detection of ions in a beamline

    NASA Astrophysics Data System (ADS)

    Schmidt, Stefan; Murböck, Tobias; Andelkovic, Zoran; Birkl, Gerhard; Nörtershäuser, Wilfried; Stahl, Stefan; Vogel, Manuel

    2015-11-01

    We have conceived, built, and operated a device for the non-destructive single-pass detection of charged particles in a beamline. The detector is based on the non-resonant pick-up and subsequent low-noise amplification of the image charges induced in a cylindrical electrode surrounding the particles' beam path. The first stage of the amplification electronics is designed to be operated from room temperature down to liquid helium temperature. The device represents a non-destructive charge counter as well as a sensitive timing circuit. We present the concept and design details of the device. We have characterized its performance and show measurements with low-energy highly charged ions (such as Ar13+) passing through one of the electrodes of a cylindrical Penning trap. This work demonstrates a novel approach of non-destructive, low noise detection of charged particles which is, depending on the bunch structure, suitable, e.g., for ion traps, low-energy beamlines or accelerator transfer sections.

  10. Modeling and optimization of single-pass laser amplifiers for high-repetition-rate laser pulses

    SciTech Connect

    Ozawa, Akira; Udem, Thomas; Zeitner, Uwe D.; Haensch, Theodor W.; Hommelhoff, Peter

    2010-09-15

    We propose a model for a continuously pumped single-pass amplifier for continuous and pulsed laser beams. The model takes into account Gaussian shape and focusing geometry of pump and seed beam. As the full-wave simulation is complex we have developed a largely simplified numerical method that can be applied to rotationally symmetric geometries. With the tapered-shell model we treat (focused) propagation and amplification of an initially Gaussian beam in a gain crystal. The implementation can be done with a few lines of code that are given in this paper. With this code, a numerical parameter optimization is straightforward and example results are shown. We compare the results of our simple model with those of a full-wave simulation and show that they agree well. A comparison of model and experimental data also shows good agreement. We investigate in detail different regimes of amplification, namely the unsaturated, the fully saturated, and the intermediate regime. Because the amplification process is affected by spatially varying saturation and exhibits a nonlinear response against pump and seed power, no analytical expression for the expected output is available. For modeling of the amplification we employ a four-level system and show that if the fluorescence lifetime of the gain medium is larger than the inverse repetition rate of the seed beam, continuous-wave amplification can be employed to describe the amplification process of ultrashort pulse trains. We limit ourselves to this regime, which implies that if titanium:sapphire is chosen as gain medium the laser repetition rate has to be larger than a few megahertz. We show detailed simulation results for titanium:sapphire for a large parameter set.

  11. 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.

    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.

  12. Intestinal permeability of chlorpyrifos using the single-pass intestinal perfusion method in the rat.

    PubMed

    Cook, Thomas J; Shenoy, Smriti S

    2003-03-01

    The intestinal transport of chlorpyrifos (CPF), an organothiophosphate pesticide, was investigated using the single-pass intestinal perfusion (SPIP) technique in male, Sprague-Dawley rats. SPIP was performed in each isolated region of the small intestine (i.e. duodenum, jejunum and ileum) with three concentrations of CPF (0.1, 2.0 and 10 microM) at a flow rate of 0.25 ml/min. Preliminary binding and stability studies were conducted to ensure that the loss of CPF in the SPIP study can be attributed to intestinal absorption. The effective permeability (P(eff)) of CPF was determined for each segment and concentration. CPF exhibits a high intestinal permeability over the length of the small intestine indicative of compounds that are well absorbed. Decreases in permeability values at the highest CPF concentration studied in the duodenum and ileum suggest a saturable transport process. Based on these results, passive, transcellular diffusion dominates the intestinal transport mechanism of CPF, with a saturable transport process evident in the duodenum and ileum. The P(eff) of CPF is in the range of drugs with high intestinal permeability and high fraction of dose absorbed indicating that CPF readily crosses the intestine. The dependence of CPF's P(eff) on concentration in the duodenum and ileum suggests that CPF is transported by a combination of mechanisms across the intestine. Using established relationships, the human fraction dose absorbed for CPF was estimated to be >99%. The permeability values obtained from this study may be useful in models of exposure assessment. PMID:12499115

  13. [In situ rats single pass perfusion intestinal absorption of the effectivein components in Radix Angelicae Pubescentis].

    PubMed

    Wu, Ya-Na; Luan, Li-Biao

    2008-01-01

    In order to study the intestinal absorption behaviors of three active constituents, columbianetin acetate, osthole and columbianadin in Radix Angelicae Pubescentis extracts, in situ rat single pass intestine perfusion (SPIP) was carried out by the perfusion solution of the extract I containing less than 10% total coumarins. The absorption of extract II containing more than 60% total coumarins was compared with that of extract I by rat colon SPIP to elucidate the influence on absorption of the different coumarin content extracts of the Chinese traditional medicine. The samples of the perfusion solution were collected in certain intervals. The concentrations of three active components in the perfusion samples were determined by HPLC method. The results demonstrated that the absorption rate constants (Ka) or apparent permeability coefficients (Papp) of columbianetin acetate, osthole and columbianadin from extract I had no significant difference among concentration ranges of 62-555 microg x mL(-1), 101-887 microg x mL(-1), 19-186 microg x mL(-1), respectively. The absorption quantity of three components was proportional to its concentration respectively and the saturate absorption phenomena were not observed. This suggested that the absorption of columbianetin acetate, osthole and columbianadin showed the passive diffusion process. Three components could be absorbed in whole intestinal sections. The Ka and Papp of three components all showed colon > duodenum > jejunum > ileum in four different regions of rat intestine. At colon, Ka and P app were significant different from the others. The Ka or Papp of three components from the extract I was significantly more than that of same components from extract II. The extract I redounded to increase the absorption of three active components. PMID:18357742

  14. [Intestinal absorption of berberine alone and in combinations by rats single pass intestinal perfusion in situ].

    PubMed

    Zhang, Yan; Zhu, Hua-Xu; Guo, Li-Wei

    2012-02-01

    The aim of the study is to investigate the effects of concentration, intestinal segments, pH, inhibitors of proteins (P-gp), Na(+)-dependent glucose transporter (SGLT1) on the intestinal absorption of berberine, and to compare intestinal absorption of berberine in combinations. With phenol red as the indicator, in situ single pass intestinal perfusion (SPIP) model was used and intestinal absorption of pure berberine at concentrations of 36.70, 46.17 and 92.33 microg x mL(-1), simulated system of HLJDT (mixture of berberine, baicalin and geniposide), HLJDT with the concentration of berberine 92.33 microg x mL(-1) in perfusion solution of different intestinal segments (duodenum, jejunum, ileum, and colon) were determined by HPLC in combination with diode array detection (DAD). The results indicated that Ka values ofberberine at different concentrations had little significant difference among that obtained after perfusing via duodenum, jejunum, ileum and colon indicating that the absorption of berberine was mainly the passive diffusion. It was also suggested that SGLT1 and P-gp might exert some effects on the absorption of berberine. Ka and Peff values of berberine in a mixture of pure compounds and HLJDT for different intestine segments of rat showed an increasing tendency and was significantly different (P < 0.05) indicating that berberine in a mixture of pure compounds and HLJDT was assimilated better in small intestine. These results indicate that the intestinal absorption of berberine may be affected by compatibility of compounds. Additionally, berberine has wide absorption window and better absorption in colon. PMID:22512037

  15. 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.

  16. SINGLE-PASS, SPLIT-STREAM OF CORN GRAIN AND STOVER: CHARACTERISTIC PERFORMANCE OF THREE HARVESTER CONFIGURATIONS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A grain combine was modified to produce single-pass, whole-plant corn harvesting with two crop streams, grain and stover. Three corn heads were used: ear-snapper, stalk-gathering and whole plant. Capture of potential stover dry matter (DM) was 30, 67, and 90% of DM for a combine harvester configur...

  17. The Surface Water and Ocean Topography Mission (SWOT): the Ka-band Radar Interferometer (KaRIn) for water level measurements at all scales

    NASA Astrophysics Data System (ADS)

    Rodriguez, Ernesto; Esteban-Fernandez, Daniel

    2010-10-01

    The Surface Water and Ocean Topography (SWOT) mission will study ocean mesoscale and submesoscale phenomena and provide an inventory of storage change and discharge for fresh water bodies and rivers. In this paper, we examine the combination of measurements that will be used by SWOT to achieve a globally consistent data set. We introduce a new channel in the SWOT measurement that combines data transmitted by the interferometer antennas and received by the radiometer antenna allows the closing of the SWOT nadir coverage gap. This new mode also allows for improved calibration between the nadir altimeter and the interferometer, resulting in consistent range measurements. Consistency in the phase measurements is achieved using a mixture of cross-over calibration combined with optimal estimation of system error drift.

  18. Intestinal permeability of metformin using single-pass intestinal perfusion in rats

    PubMed Central

    Song, Nai-Ning; Li, Quan-Sheng; Liu, Chang-Xiao

    2006-01-01

    AIM: To characterize the intestinal transport and mechanism of metformin in rats and to investigate whether or not metformin is a substrate for P-glycoprotein (P-gp). METHODS: The effective intestinal permeability of metformin was investigated using single-pass intestinal perfusion (SPIP) technique in male Waster rats. SPIP was performed in three isolated intestinal segments (duodenum, jejunum and ileum) at the same concentration of metformin (50 μg/mL) to test if the intestinal transport of metformin exhibited site-dependent changes, and in a same isolated intestinal segment (duodenal segment) at three different concentrations of metformin (10, 50, 200 μg/mL) to test if the intestinal transport of metformin exhibited concentration-dependent changes. Besides, P-gp inhibitor verapamil (400 μg/mL) was co-perfused with metformin (50 μg/mL) in the duodenum segment to find out if the intestinal absorption of metformin was affected by P-gp exiting along the gastrointestinal track. Stability studies were conducted to ensure that the loss of metformin could be attributed to intestinal absorption. RESULTS: The effective permeability values (Peff) of metformin in the jejunum and ileum at 50 μg/mL were significantly lower than those in the duodenum at the same concentration. Besides, Peff values in the duodenum at high concentration (200 μg/mL) were found to be significantly lower than those at low and medium concentrations (10 and 50 μg/mL). Moreover the co-perfusion with verapamil did not increase the Peff value of metformin at 50 μg/mL in the duodenum. CONCLUSION: Metformin could be absorbed from the whole intestine, with the main absorption site at duodenum. This concentration-dependent permeability behavior in the duodenum indicates that metformin is transported by both passive and active carrier-mediated saturable mechanism. The Peff value can not be increased by co-perfusion with verapamil, indicating that absorption of metformin is not efficiently transported by P-gp in the gut wall. Furthermore metformin is neither a substrate nor an inducer of P-gp. Based on the Peff values obtained in the present study and using established relationships, the human fraction dose absorbed for metformin is estimated to be 74%-90% along human intestine. PMID:16810761

  19. Single-Pass Flow Through (SPFT) Testing of Fluidized-Bed Steam Reforming (FBSR) Waste Forms

    SciTech Connect

    Lorier, T. H.; Pareizs, J. M.; Jantzen, C. M.

    2005-08-15

    Two samples of fluidized-bed steam reforming (FBSR) mineral waste form product were subjected to single-pass flow-through (SPFT) testing. Sample LAW 1123 resulted from pilot-scale FBSR processing with a Hanford Envelope A low-activity waste (LAW) simulant. Sample SBW 1173 resulted from pilot-scale FBSR processing with an Idaho National Laboratory (INL) simulant commonly referred to as sodium-bearing waste (SBW). The pilot-scale waste forms were made at the Science and Technology Applications Research (STAR) facility in Idaho Falls, Idaho. The durability of the two FBSR waste forms was assessed via the SPFT test in this study. Both samples were multiphase mineral waste forms, so the SPFT test results provide an overall release rate from the multiple mineral species in each sample and are dependent on the amount of each phase present and the mineralogy of the phases present. SPFT testing was performed at temperatures of 25, 40, 70, and 90 C on LAW 1123, while SBW 1173 was only tested at 70 and 90 C. The 70 and 90 C data were compared to each other and the LAW-1123 results were compared to previous testing performed by the Pacific Northwest National Laboratory (PNNL) on a LAW Envelope C (high organic content) waste simulant. The objectives of this study were to obtain forward dissolution rate data for both STAR FBSR bed products (using SPFT tests). Also, a qualitative comparison of the FBSR bed products to a glass waste form (specifically the low-activity reference material (LRM) glass) was performed. For these comparisons, the relative surface areas of the FBSR and glass products had to be measured. Due to the more porous and irregular surface of FBSR bed products, the surface area of the bed products was determined using the Brunauer, Emmett, and Teller (BET) measurement method. The surface area of a glass is much smoother and the calculated geometric surface area is typically used for determining dissolution behavior. Presently there are no specifications or standard release rates that the FBSR tested materials have to meet, e.g. the data from the FBSR testing is normally used during subsequent Performance Assessment (PA) calculations. Since a PA calculation is not part of this study, the LAW and SBW steam reforming samples were compared to each other, to previous LAW FBSR SPFT results, and to the results from the LRM reference glass. The experimental durability data generated from this study suggests that an FBSR mineral waste form product would be an adequate alternative form to borosilicate glass. The tested FBSR mineral waste forms showed normalized release rates for matrix elements such as Si to be more than 200X slower than the LRM glass. However, further durability testing and mineral phase information is recommended to further substantiate these findings.

  20. Single-pass versus two-pass boat electrofishing for characterizing river fish assemblages: Species richness estimates and sampling distance

    USGS Publications Warehouse

    Meador, M.R.

    2005-01-01

    Determining adequate sampling effort for characterizing fish assemblage structure in nonwadeable rivers remains a critical issue in river biomonitoring. Two-pass boat electrofishing data collected from 500-1,000-m-long river reaches as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program were analyzed to assess the efficacy of single-pass boat electrofishing. True fish species richness was estimated by use of a two-pass removal model and nonparametric jackknife estimation for 157 sampled reaches across the United States. Compared with estimates made with a relatively unbiased nonparametric estimator, estimates of true species richness based on the removal model may be biased, particularly when true species richness is greater than 10. Based on jackknife estimation, the mean percent of estimated true species richness collected in the first electrofishing pass (p??j,s1) for all 157 reaches was 65.5%. The effectiveness of single-pass boat electrofishing may be greatest when the expected species richness is relatively low (>10 species). The second pass produced additional species (1-13) in 89.2% of sampled reaches. Of these additional species, centrarchids were collected in 50.3% of reaches and cyprinids were collected in 45.9% of reaches. Examination of relations between channel width ratio (reach length divided by wetted channel width) and p??j,s1 values provided no clear recommendation for sampling distances based on channel width ratios. Increasing sampling effort through an extension of the sampled reach distance can increase the percent species richness obtained from single-pass boat electrofishing. When single-pass boat electrofishing is used to characterize fish assemblage structure, determination of the sampling distance should take into account such factors as species richness and patchiness, the presence of species with relatively low probabilities of detection, and human alterations to the channel.

  1. Keck Interferometer

    NASA Astrophysics Data System (ADS)

    Swanson, P.; Colavita, M.; Boden, A.; van Belle, G.; Shao, M.

    1998-01-01

    The Keck Interferometer is being developed by JPL and CARA as one of the ground-based components of NASA's Origins program. The system will interferometrically combine the two 10-m Keck telescopes with four proposed 1.8-m outrigger telescopes located at the periphery of the Keck site on Mauna Kea. Using an isoplanatic reference, adaptive optics on the Keck telescopes will provide phased wavefronts to the interferometer, which, in conjuction with wavefront path length matching in the interferometer (cophasing), will provide high sensitivity. Back-end instrumentation will include two-way combiners for cophasing and single-baseline measurements, a nulling combiner for high-dynamic range measurements, and a multiway imaging combiner. Science objectives include the measurement of exozodical dust around other stars, the detection of warm stellar companions through multi-color differential-phase measurements, astrometric searches for Jupiter and Uranus mass stellar companions, and a wide range of infrared imaging.

  2. Single pass, THz spectral range free-electron laser driven by a photocathode hybrid rf linear accelerator

    NASA Astrophysics Data System (ADS)

    Lurie, Yu.; Friedman, A.; Pinhasi, Y.

    2015-07-01

    A single pass, THz spectral range free-electron laser (FEL) driven by a photocathode hybrid rf-LINAC is considered, taking the Israeli THz FEL project developed in Ariel University as an example. Two possible configurations of such FEL are discussed: an enhanced coherent spontaneous emission FEL, and a prebunched FEL utilizing periodically modulated short electron beam pulses. A general study of the FEL configurations is carried out in the framework of a space-frequency approach, realized in WB3D numerical code. The configurations are studied and compared based on preliminary parameters of a drive hybrid rf-LINAC gun under development in University of California, Los Angeles.

  3. UV x-ray free electron lasers through high-gain single pass amplifier: Basic principles and issues

    SciTech Connect

    Kim, K.J.

    1994-09-01

    The author reviews the basic principles of high gain free electron laser amplifier in single pass configuration for generation of intense, tunable radiation for wavelength shorter than 1,000 {angstrom}. Two schemes are discussed: for wavelength region between 1,000--100 {angstrom}, the high gain harmonic generation of a coherent input radiation can be used. For x-ray wavelength as short as a few {angstrom}, the self-amplified spontaneous emission is currently the only known free electron laser scheme. The author also presents a brief introduction of various key issues in realizing these schemes, which will be discussed in detail in other papers in these proceedings.

  4. Study on cross-section clad profile in coaxial single-pass cladding with a low-power laser

    NASA Astrophysics Data System (ADS)

    Liu, Jichang; Li, Lijun

    2005-09-01

    In this paper, a model of cross-section clad profile on the substrate in coaxial single-pass cladding with a low-power laser was studied. The static model of powder mass concentration distribution at cold-stream conditions was defined as a Gaussian function. In coaxial single-pass cladding with a low-power laser, since the influence of surface tension, gravity and gas flow on the clad bead could be neglected, the cross-section profile of the clad bead deposited by a low-power laser on the substrate was dominated by the powder concentration at each point on the pool and the time when the material was liquid at this point. The height of each point on the cross-section clad profile was defined as a definite integration of a Gaussian function from the moment at which the melt pool was just arriving at the point to the moment at which the point left the melt pool. In the presented experiment, powder of Steel 63 (at 0.63 wt% C) was deposited on a substrate of Steel 20 (at 0.20 wt% C) at the laser power of 135 W. The experimental results testified the model.

  5. Using a Ground Based radar interferometer during emergency: the case of A3 motorway (Salerno Reggio-Calabria) treated by landslide

    NASA Astrophysics Data System (ADS)

    Del Ventisette, Chiara; Intrieri, Emanuele; Luzi, Guido; Casagli, Nicola

    2010-05-01

    An application of Ground Based radar interferometry (GB-InSAR) technique to monitor a landslide threatening infrastructures in emergency conditions is presented. During December 2008 and January 2009 intense rainfalls occurred in Italy, especially in the southern regions. These rain events occurred in the last days of January, worsened the already critical hydrogeological conditions of some areas and triggered many landslides. One of these landslides, named Santa Trada landslide, is located close to a periodical stream called Fiumara di Santa Trada, near Villa San Giovanni municipality (Reggio Calabria, Calabria Region). The volume involved is about 100 000 m3. This estimate represents the case of a collapse of the landslide which destabilize a larger part of the slope, involving other areas delimited by some fractures observed upstream. Nevertheless the landslide does not directly threaten the roadway, its complete collapse would hit the pillars of a motorway viaduct. Through GB-InSAR data it has been possible to obtain an overview of the area affected by movement and to quantify the displacements magnitude. The main benefit of the system was not only limited to the capability of fully characterizing the landslide in spatial terms, it also permitted emergency operators to follow, during the whole campaign, the evolution of the mass movement and to study its cinematic behaviour. This aspect is fundamental to evaluate the volume of the material involved and to assess the temporal evolution of the risk scenario. The GB-InSAR installed at Santa Trada points up toward the landslide from a distance of 250 m. The apparatus produces a synthesized radar image of the observed area every 6 minutes, night and day, with a pixel resolution of about 0.75 m in range and 1.2 m on average in cross range, performing a millimeter accuracy on the final displacement maps. The interferometric analysis of sequences of consecutive images allows the operator to derive the entire line of sight (LoS) displacement field of the observed portion of the slope in the elapsed time. Despite the GB-InSAR can measure only the displacement component along the LoS direction, an accurate alignment of the system with respect to the moving direction, allowed us to assess almost completely the motion of the landslide. The landslide, never detected before, occurred on the 30th of January; at 8.00 PM of the same day the Civil Protection Department entrusted the monitoring of the unstable slope to the Earth Science Department - University of Firenze. On the 31st of January a GB-InSAR system was installed (by Ellegi-Lisalab s.r.l.) and, after the test, carried out on the 1st of February, just 48 hours after the occurrence of the landslide, the monitoring campaign started. On the 2nd of February, thanks to GB-InSAR data interpretation, the A3 motorway, previously inhibited to vehicular traffic, was already partially re-opened. The opening of the A3 motorway was particularly significant considering that the by-pass constituted by the state highway SS18 and other 28 country roads in the neighbour area were inhibited due to rainfall. The campaign lasted until the 24th of April when the alarm ceased definitely. The brief chronicle and the analysis of the data acquired during this period described in this contribution highlights the potentiality of this system during emergency.

  6. Michelson Interferometer

    NASA Technical Reports Server (NTRS)

    Rogers, Ryan

    2007-01-01

    The Michelson Interferometer is a device used in many applications, but here it was used to measure small differences in distance, in the milli-inch range, specifically for defects in the Orbiter windows. In this paper, the method of using the Michelson Interferometer for measuring small distances is explained as well as the mathematics of the system. The coherence length of several light sources was calculated in order to see just how small a defect could be measured. Since white light is a very broadband source, its coherence length is very short and thus can be used to measure small defects in glass. After finding the front and back reflections from a very thin glass slide with ease and calculating the thickness of it very accurately, it was concluded that this system could find and measure small defects on the Orbiter windows. This report also discusses a failed attempt for another use of this technology as well as describes an area of promise for further analysis. The latter of these areas has applications for finding possible defects in Orbiter windows without moving parts.

  7. Lucretia: A Matlab-Based Toolbox for the Modellingand Simulation of Single-Pass Electron Beam Transport Systems

    SciTech Connect

    Tenenbaum, P.; /SLAC

    2005-09-30

    We report on Lucretia, a new simulation tool for the study of single-pass electron beam transport systems. Lucretia supports a combination of analytic and tracking techniques to model the tuning and operation of bunch compressors, linear accelerators, and beam delivery systems of linear colliders and linac-driven Free Electron Laser (FEL) facilities. Extensive use of Matlab scripting, graphics, and numerical capabilities maximize the flexibility of the system, and emphasis has been placed on representing and preserving the fixed relationships between elements (common girders, power supplies, etc.) which must be respected in the design of tuning algorithms. An overview of the code organization, some simple examples, and plans for future development are discussed.

  8. Single Pass Flow-Through (SPFT) Test Results of Fluidized Bed Steam Reforming (FBSR) Waste Forms used for LAW Immobilization

    SciTech Connect

    Neeway, James J.; Qafoku, Nikolla; Williams, Benjamin D.; Valenta, Michelle M.; Cordova, Elsa A.; Strandquist, Sara C.; Dage, DeNomy C.; Brown, Christopher F.

    2012-03-20

    Several supplemental technologies for treating and immobilizing Hanford low activity waste (LAW) are being evaluated. One such immobilization technology being considered is the Fluidized Bed Steam Reforming (FBSR) granular product. The FBSR granular product is composed of insoluble sodium aluminosilicate (NAS) feldspathoid minerals. Production of the FBSR mineral product has been demonstrated both at the industrial and laboratory scale. Single-Pass Flow-Through (SPFT) tests at various flow rates have been conducted with the granular products fabricated using these two methods. Results show that the materials exhibit a relatively low forward dissolution rate on the order of 10-3 g/(m2d) with the material made in the laboratory giving slightly higher values.

  9. Novel interferometer

    NASA Astrophysics Data System (ADS)

    Williamson, Ray

    2004-01-01

    Thin, visibly opaque components for use in infrared transmission present a challenge in tolerancing and manufacture: Most optical shops do not have access to infrared interferometry and so must evaluate the opposing surfaces in visible light. The inevitable bending of thin parts will create surface deformations that are individually far in excess of allowable limits. However if the opposing surface deformations track each other, the part may be perfectly functional. The dilemma is between over-specification of the surfaces and consequent multiplication in costs and schedule; vs. verification in the infrared, thus eliminating most perfectly competent vendors. Herein, I present a novel interferometric cavity setup utilizing a standard, commercial interferometer, in which the test beam reflects twice from each side, in point by point registration across the aperture. I also present fringe-scaling factors based on angle of incidence and index of refraction. The cavity error can be conveniently subtracted. Small wedge can be measured or eliminated, or if desired, large wedge can be eliminated. The components can, thus, be specified and verified functionally with significant reduction in difficulty and cost. NOTE: this work was presented at SPIE in 1991, v 1527 p 188. The audience that day was very small. I think the technique remains valuable and virtually unknown.

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

    SciTech Connect

    Rivera-Sanfeliz, Gerant Kinney, Thomas B.; Rose, Steven C.; Agha, Ayad K.M.; Valji, Karim; Miller, Franklin J.; Roberts, Anne C.

    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.

  11. Merits of a sub-harmonic approach to a single-pass, 1.5-{Angstrom} FEL

    SciTech Connect

    Fawley, W.M.; Nuhn, H.D.; Bonifacio, R.; Scharlemann, E.T.

    1995-03-01

    SLAC/SSRL and collaborators elsewhere are studying th physics of a single-pass, FEL amplifier operating in th 1 -- 2 {Angstrom}, wavelength region based on electron beams from the SLAC linac at {approximately} 15 GeV energy. Hoping to reduce the total wiggler length needed to reach saturation when starting from shot noise, we have examined the benefits of making the first part of the wiggler resonant at a subharmonic wavelength (e.g. 4.5 {Angstrom}) at which the gain length can be significantly shorter. This leads to bunching of the electron beam at both the subharmonic and fundaments wavelengths, thus providing a strong coherent ``seed`` for exponential growth of radiation at the fundamental in the second part of the wiggler. Using both multi-harmonic and multi-frequency 2D FEL simulation codes, we have examined the predicted performance of such devices and the sensitivity to electron beam parameters such as current, emittance, and instantaneous energy spread.

  12. Intestinal absorptive transport of Genkwanin from Flos genkwa using a single-pass intestinal perfusion rat model.

    PubMed

    Jiang, Cui-Ping; He, Xin; Yang, Xiao-Lin; Zhang, Su-Li; Li, Hui; Song, Zi-Jing; Zhang, Chun-Feng; Yang, Zhong-Lin; Li, Ping

    2014-01-01

    To investigate the absorptive transport behavior of genkwanin and the beneficial effects of monoterpene enhancers with different functional groups, the single-pass intestinal perfusion (SPIP) of rats was used. The results showed that genkwanin was segmentally-dependent and the best absorptive site was the duodenum. The effective permeability coefficient (P eff ) was 1.97 × 10(-4) cm/s and the absorption rate constant (Ka) was 0.62 × 10(-2) s(-1). Transepithelial transportation descended with increasing concentrations of genkwanin. This was a 1.4-fold increase in P eff by probenecid, whereas a 1.4-fold or 1.6-fold decrease was observed by verapamil and pantoprazole, respectively. Furthermore, among the absorption enhancers, the enhancement with carbonyl (camphor and menthone) was higher than that with hydroxyl (borneol and menthol). The concentration-independent permeability and enhancement by coperfusion of probenecid indicated that genkwanin was transported by both passive diffusion and multidrug resistance protein (MDR)-mediated efflux mechanisms. PMID:24707867

  13. Evaluation of a single-pass intestinal-perfusion method in rat for the prediction of absorption in man.

    PubMed

    Salphati, L; Childers, K; Pan, L; Tsutsui, K; Takahashi, L

    2001-07-01

    Prediction of the fraction of dose absorbed from the intestine (Fa) in man is essential in the early drug discovery stage. In-vitro assays in Caco-2 and MDCK cells are routinely used for that purpose, and their predictive value has been reported. However, in-situ techniques might provide a more accurate estimation of Fa. In this study, we evaluated a single-pass intestinal-perfusion (SPIP) method in the rat for its use in the prediction of absorption in man and compared it with a previous report using cell-based assays. Effective permeability coefficients (Peff) were determined in rats for 14 compounds, and ranged from 0.043x 10(-4) cm s(-1) to 1.67 x 10(-4) cm s(-1). These values strongly correlated (r2 = 0.88) with reported Peff values for man. In addition, the Spearman rank correlation coefficient calculated for in-situ-derived Peff and absorption in man was 0.92 while for the previously tested in-vitro Caco-2 and MDCK systems vs absorption in man, the correlation coefficients were 0.61 and 0.59, respectively. SPIP provided a better prediction of human absorption than the cell-based assays. This method, although time consuming, could be used as a secondary test for studying the mechanisms governing the absorption of new compounds, and for predicting more accurately the fraction absorbed in man. PMID:11480535

  14. 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.

  15. An efficient continuous-wave and Q-switched single-pass two-stage Ho:YLF MOPA system

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, Jacek; Jabczynski, Jan Karol; Zendzian, Waldemar

    2015-04-01

    We report on the efficient operation of an Ho:YLF laser single-pass in-band pumped by a Tm-doped fiber laser. The research in a continuous-wave (CW) operation in an oscillator scheme was done for a crystal of 0.5 at% Ho dopant concentration and the length of 30 mm for the output coupler transmittances of TOC=10%, 20%, 30% and 40%. At room temperature, for the output coupling transmission of 20%, the maximum CW output power of 24.5 W for 82.5 W of incident pump power, corresponding to the slope efficiency of 35.4% and optical-to-optical conversion efficiency of 29.7% was achieved. The highest slope efficiency of 81.6% with respect to absorbed pump power was obtained. Carrying out the measurements of the laser spectrum, for the out-coupling transmittance of TOC=30%, we observed a very short time wavelength shift between 2051.5 and 2062.4 nm in an Ho:YLF laser operation. Trying to fully utilize the pump power unabsorbed by the active crystal in an oscillator stage, an amplifier system based on two additional Ho:YLF crystals was developed. For the output coupling transmission of 40% the slope efficiency increased from 31.5% in an oscillator scheme to 47.3% with respect to the incident pump power in a two-stage amplifier scheme with a beam quality parameter of M2 better than 1.1. For a Q-switched operation, for the maximum incident pump power and the pulse repetition frequency (PRF) of 1 kHz, pulse energies of 18.5 mJ with a 22 ns FWHM pulse width corresponding to 841 kW peak power in the amplifier system were recorded.

  16. [Intestinal absorption of the effective components of Schisandra chinensis Baill by rats single-pass perfusion in situ].

    PubMed

    Chen, Xin-Min; Li, Jun-Song; Li, Wen; Han, Lei; Liu, Xun-Hong; Di, Liu-Qing; Cai, Bao-Chang

    2010-05-01

    The aim of the study is to investigate rat intestinal absorption behavior of three main active components, schisandrol A, schisandrin A and schisandrin B in Schisandra chinensis Baill extracts in intestine of rats. With phenol red as the indicator, in situ single pass intestinal perfusion (SPIP) model was used and the concentrations of three main active components in perfusion solution of different intestinal segments (duodenum, jejunum, ileum, and colon) were determined by HPLC in combination with diode array detection. The results showed that the absorption rate constant (Ka) and effective permeability values (Peff) of three main active components in Schisandra chinensis Baill extracts had significant difference (P < 0.05) at different concentrations of perfusion solution, the Ka and Peff first increased and then decreased with the increase of drug concentration, the middle concentration was higher than those of the other two concentrations. The saturate absorption phenomena were observed, and it suggested that the transport mechanisms of three main active components in vivo were similar to active transport or facilitated diffusion. Three active components can be well absorbed in all of the intestinal segments, while duodenum is the best absorption region. The Ka and Peff of three active components in jejunum and ileum had no significant difference (P > 0.05). The absorption of the three active components displayed significant difference (P < 0.05) at different intestinal segments of rats. Schisandrin A had the best absorption in duodenum. The Ka and Peff among three active components were sequenced as follows: schisandrin A > schisandrin B > schisandrol A in other intestinal segments, and there is significant difference (P < 0.05) between them. PMID:20931771

  17. 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.

  18. Evaluation of Intermittent Hemodialysis in Critically Ill Cancer Patients with Acute Kidney Injury Using Single-Pass Batch Equipment

    PubMed Central

    Torres da Costa e Silva, Verônica; Costalonga, Elerson C.; Oliveira, Ana Paula Leandro; Hung, James; Caires, Renato Antunes; Hajjar, Ludhmila Abrahão; Fukushima, Julia T.; Soares, Cilene Muniz; Bezerra, Juliana Silva; Oikawa, Luciane; Yu, Luis; Burdmann, Emmanuel A.

    2016-01-01

    Background Data on renal replacement therapy (RRT) in cancer patients with acute kidney injury (AKI) in the intensive care unit (ICU) is scarce. The aim of this study was to assess the safety and the adequacy of intermittent hemodialysis (IHD) in critically ill cancer patients with AKI. Methods and Findings In this observational prospective cohort study, 149 ICU cancer patients with AKI were treated with 448 single-pass batch IHD procedures and evaluated from June 2010 to June 2012. Primary outcomes were IHD complications (hypotension and clotting) and adequacy. A multiple logistic regression was performed in order to identify factors associated with IHD complications (hypotension and clotting). Patients were 62.2 ± 14.3 years old, 86.6% had a solid cancer, sepsis was the main AKI cause (51%) and in-hospital mortality was 59.7%. RRT session time was 240 (180–300) min, blood/dialysate flow was 250 (200–300) mL/min and UF was 1000 (0–2000) ml. Hypotension occurred in 25% of the sessions. Independent risk factors (RF) for hypotension were dialysate conductivity (each ms/cm, OR 0.81, CI 0.69–0.95), initial mean arterial pressure (each 10 mmHg, OR 0.49, CI 0.40–0.61) and SOFA score (OR 1.16, CI 1.03–1.30). Clotting and malfunctioning catheters (MC) occurred in 23.8% and 29.2% of the procedures, respectively. Independent RF for clotting were heparin use (OR 0.57, CI 0.33–0.99), MC (OR 3.59, CI 2.24–5.77) and RRT system pressure increase over 25% (OR 2.15, CI 1.61–4.17). Post RRT blood tests were urea 71 (49–104) mg/dL, creatinine 2.71 (2.10–3.8) mg/dL, bicarbonate 24.1 (22.5–25.5) mEq/L and K 3.8 (3.5–4.1) mEq/L. Conclusion IHD for critically ill patients with cancer and AKI offered acceptable hemodynamic stability and provided adequate metabolic control. PMID:26938932

  19. Phase shifting interferometer

    DOEpatents

    Sommargren, G.E.

    1999-08-03

    An interferometer is disclosed 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. 11 figs.

  20. 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.

  1. The Glacier and Ice Sheet Topography Interferometer: An Update on a Unique Sensor for High Accuracy Swath Mapping of Land Ice

    NASA Astrophysics Data System (ADS)

    Moller, D.; Heavey, B.; Hensley, S.; Hodges, R.; Rengarajan, S.; Rignot, E.; Sadowy, G.; Simard, M.; Zawadzki, M.

    2007-12-01

    We discuss the innovative concept and technology development of a Ka-band (35 GHz) radar for mapping the surface topography of glaciers and ice sheets. The "Glacier and Land Ice Surface Topography Interferometer" (GLISTIN) is a single-pass, single platform interferometric synthetic aperture radar (InSAR) with an 8mm wavelength, which minimizes snow penetration yet remains relatively impervious to atmospheric attenuation. Such a system has the potential for delivering topographic maps at high spatial resolution, high vertical accuracy, independent of cloud cover, with a subseasonal update and would greatly enhance current observational and modeling capabilities of ice mass-balance and glacial retreat. To enable such measurements, a digitally beamformed antenna array is utilized to provide a wide measurement swath at a technologically feasible transmit power. To prove this concept and advance the technology readiness of this design we are currently funded by the NASA Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP) to build and test a 1m x 1m digitally-beamformed (DBF) Ka-band slotted waveguide antenna with integrated digital receivers. This antenna provides 16 simultaneous receive beams, effectively broadening the swath without reducing receive antenna gain. The implementation of such a large aperture at Ka-band presents many design, manufacturing and calibration challenges which are addressed as part of this IIP. The integrated DBF array will be fielded at the Jet Propulsion Laboratory's antenna range to demonstrate the overall calibration, beamforming and interferometric performance through creation of topographic imagery of the local Arroyo Seco. Currently entering the third year of the program, we will overview the system concept, array implementation and status of the technology. While the IIP addresses the development of the major technology challenges, an additional effort will demonstrate the phenomenology of the measurement by adapting the NASA ESTO-funded Uninhabited Aerial Vehicle - Synthetic Aperture Radar (UAVSAR) system for Ka-band single-pass interferometry. The conversion to Ka-Band will utilize the modular UAVSAR system originally designed for L-Band operation, retaining the radar control, data acquisition and processing infrastructure and requiring only minor pod and RF modifications. We will fly the Ka-Band interferometer aboard the UAVSAR platform over regions of Greenland, flying a grid over Jakobshavn glacier, then a transect from the coast to Swiss Camp ending at Greenland's Summit. Over a period of 4-5 weeks at the beginning of the melt season, these flight missions will be repeated in different snow/ice conditions. The flight data will be compared with airborne laser altimetry (Airborne Topographic Mapper lidar instrument, NASA GSFC/Wallops), field observations (GPS data at Swiss Camp, Summit), and climate data from the Automatic Weather Station (Colorado University) network (snowfall, corrected for densification) to estimate penetration and produce topographic surface maps. Topography is an essential piece of information for glaciology and a high-quality topographic map (tens of cm height accuracy over 10m pixels) will be produced. The experiment will pave the way to making more topographic products available to glaciologists and aid in the design a spaceborne mission capable of delivering similar products at the continental scale.

  2. Elevation Changes on Malaspina, Agassiz and Marvine Glaciers, Alaska, from the Shuttle Radar Topography Mission

    NASA Astrophysics Data System (ADS)

    Muskett, R. R.; Lingle, C. S.; Tangborn, W. V.; Rabus, B.

    2002-12-01

    The Chugach-St. Elias Mountains bordering the Gulf of Alaska is the location of the largest connected glacier and icefield complex in continental North America: The Bering and Malaspina glacier systems (Molnia, 1993; Sharp, 1951). The Malaspina Glacier piedmont lobe has an area of about 2200 km2. Agassiz and Marvine Glacier, on the west-east sides of the Malaspina piedmont, have areas of about 591 and 223 km2 respectively. The combined Malaspina-Seward system, including tributaries, has an area of about 4,300 km2. Malaspina has a quasi-periodic surge period of 20 to 30 years. The Shuttle Radar Topography Mission/X-Synthetic Aperture Radar (SRTM/X-SAR), flown on STS-99 (February 2000) was the first spaceborne single-pass interferometric SAR mission (Geudtner and others, 2002). The SRTM/X-SAR system was composed of C and X-band SAR. The single-pass SAR interferometer configuration with an inboard (transmit and receive) and outboard (receive only) antenna system enabled the removal of large error sources inherent with the repeat-pass technique. X-band digital elevation models (DEM) produced by the German Remote Sensing Center (DFD) have a nominal pixel size of 25 m-by-25 m in UTM projection. The vertical and horizontal reference datum is World Geodetic System 84 (WGS 84). Nominal vertical accuracy is 6 m (16 m absolute) and horizontal accuracy is 15 m (20 m absolute) at the 90% confidence level. We present new surface elevation changes on the Malaspina piedmont lobe, Agassiz and Marvine Glaciers from 1972-'73 to 2000 based on spatial analysis of co-located Shuttle Radar Topography Mission X-band DEM with United States Geological Survey DEMs. X-band DEM elevations were changed from the WGS 84 vertical datum (ellipsoid) to the GEOID 99-Alaska (NOAA National Geodetic Survey geoid) datum. USGS DEMs were transformed from North America Datum 1927 (NAD 27) to WGS 84 in UTM projection. A correction for X-band radar penetration depth of snow cover is in progress. Preliminary results indicate the Malaspina piedmont surface lowered on average by 43 +/- 4 m from 1972 to 2000 (1.6 +/- 0.1 m a-1) for a volume loss of 59 +/- 5 km3 in water equivalent (we). The spatial distribution of surface lowering is non-uniform for all three glaciers. The Marvine Glacier shows an average of 50 +/- 4 m we of surface lowering. The Agassiz Glacier shows an average of 24 +/- 4 m we of surface lowering. However, Agassiz Glacier has a bulge of surface rising up to 52 +/- 4 m, about 4 km in diameter, located across from Agassiz Lakes. Geudtner and 3 others, Interferometric alignment of the X-SAR antenna system on the Space Shuttle Radar Topography Mission, IEEE Trans. on Geoscience RS, 40 (5), 995-1005, 2002. Molnia, Major surge of the Bering Glacier, Eos, 74 (29), 321-322, 1993. Sharp, Accumulation and ablation on the Seward-Malaspina glacier system, Canada-Alaska, Bull. Geo. Soc. Am., 62, 725-744, 1951.

  3. Self-calibrating interferometer

    SciTech Connect

    Nussmeier, T.A.

    1982-10-26

    A self-calibrating interferometer is disclosed which forms therein a pair of Michelson interferometers with one beam length of each Michelson interferometer being controlled by a common phase shifter. The transfer function measured from the phase shifter to either of a pair of detectors is sinusoidal with a full cycle for each half wavelength of phase shifter travel. The phase difference between these two sinusoidal detector outputs represents the optical phase difference between a path of known distance and a path of unknown distance.

  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. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, G.E.

    1996-08-29

    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. 8 figs.

  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. Michelson and His Interferometer

    ERIC Educational Resources Information Center

    Shankland, Robert S.

    1974-01-01

    Presents a brief historical account of Michelson's invention of his interferometer with some subsequent ingenious applications of its capabilities for precise measurement discussed in details, including the experiment on detrmination of the diameters for heavenly bodies. (CC)

  10. The Palomar Testbed Interferometer

    NASA Technical Reports Server (NTRS)

    Colavita, M. M.; Wallace, J. K.; Hines, B. E.; Gursel, Y.; Malbet, F.; Palmer, D. L.; Pan, X. P.; Shao, M.; Yu, J. W.; Boden, A. F.

    1999-01-01

    The Palomar Testbed Interferometer (PTI) is a long-baseline infrared interferometer located at Palomar Observatory, California. It was built as a testbed for interferometric techniques applicable to the Keck Interferometer. First fringes were obtained in 1995 July. PTI implements a dual-star architecture, tracking two stars simultaneously for phase referencing and narrow-angle astrometry. The three fixed 40 cm apertures can be combined pairwise to provide baselines to 110 m. The interferometer actively tracks the white-light fringe using an array detector at 2.2 microns and active delay lines with a range of +/-38 m. Laser metrology of the delay lines allows for servo control, and laser metrology of the complete optical path enables narrow-angle astrometric measurements. The instrument is highly automated, using a multiprocessing computer system for instrument control and sequencing.

  11. High-precision Ice Surface Topography Mapping Using Radar Interferometry

    NASA Astrophysics Data System (ADS)

    Moller, D.; Hensley, S.; Michel, T.; Rignot, E. J.; Simard, M.; Krabill, W. B.; Sonntag, J. G.

    2010-12-01

    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 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. 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. However, for this application the electromagnetic wave will penetrate an unknown amount into the snow cover thus producing an effective bias that must be calibrated. To evaluate this, GLISTIN-A flew a coordinated collection with the NASA Wallops Airborne Topographic Mapper (ATM) on a transect from Greenland’s Summit to its West coast. Two field calibration sites were established at Colorado Institute for Research in Environmental Science’s Swiss Camp and the National Science Foundation’s Summit station. Additional collections entailed flying a mosaic over Jakobshavn glacier which was repeated after 6 days to reveal surface dynamics. Through detailed calibration and inter-sensor comparisons we were able to observe penetration biases and compare them with theoretical expectations. We also demonstrated GLISTIN-A’s capability to measure the topography of large glacier systems in a seamless fashion and accurately measuring volume changes with a high level of spatial detail. In particular, repeating the airborne campaigns to observe elevation changes over time will allow very accurate volume change measurements. Not only is this very important for mass balance studies to have a precise mass-loss estimate, but the spatial pattern can reveal ice dynamics effects and surface mass balance effects. In this manner a high resolution, high-precision topographic mapping capability is an ideal complement to the ICESat, ICESat II and Cryosat altimeters. Interpolating between the high-accuracy elevation profiles from altimeters such as the ATM or ICESat II with the high-resolution GLISTIN-A swath will enable detailed ice-surface topography maps and extended spatial coverage. The result is the potential for higher fidelity mass-balance estimates and improved observational coverage. Upgrades are currently underway to improve the performance and portability of GLISTIN-A such that, onboard a long-range aircraft this radar can map Greenland’s significant glaciers in a few days. The upgraded GLISTIN-A will be compatible with GlobalHawk installation making, Antarctica basin and coastal mapping feasible. GLISTIN will make more topographic products available to glaciologists, initially through dedicated airborne campaigns or ultimately, perhaps, as a satellite mission.

  12. Continuous-wave sodium D2 resonance radiation generated in single-pass sum-frequency generation with periodically poled lithium niobate.

    PubMed

    Yue, J; She, C-Y; Williams, B P; Vance, J D; Acott, P E; Kawahara, T D

    2009-04-01

    With two cw single-mode Nd:YAG lasers at 1064 and 1319 nm and a periodically poled lithium niobate crystal, 11 mW of 2 kHz/100 ms bandwidth single-mode tunable 589 nm cw radiation has been detected using single-pass sum-frequency generation. The demonstrated conversion efficiency is approximately 3.2%[W(-1) cm(-1)]. This compact solid-state light source has been used in a solid-state-dye laser hybrid sodium fluorescence lidar transmitter to measure temperatures and winds in the upper atmosphere (80-105 km); it is being implemented into the transmitter of a mobile all-solid-state sodium temperature and wind lidar under construction. PMID:19340230

  13. Single Pass Flow-Through (SPFT) Test Results of Fluidized Bed Steam Reforming (FBSR) Waste Forms used for LAW Immobilization - 12252

    SciTech Connect

    Neeway, James J.; Qafoku, Nikolla P.; Williams, Benjamin D.; Valenta, Michelle M.; Cordova, Elsa A.; Strandquist, Sara C.; Dage, DeNomy C.; Brown, Christopher F.

    2012-07-01

    Several supplemental technologies for treating and immobilizing Hanford low activity waste (LAW) are being evaluated. One such immobilization technology being considered is the Fluidized Bed Steam Reforming (FBSR) product, which is granular and will be monolithed into a final waste form. The granular component is composed of insoluble sodium aluminosilicate (NAS) feldspathoid minerals. Production of the FBSR mineral product has been demonstrated at the industrial, engineering, and laboratory scales. Single-Pass Flow-Through (SPFT) tests at various flow rates have been conducted with the granular products fabricated using the engineering- and laboratory-scale methods. Results show that the forward dissolution rate for the engineering-scale mineral product is 0.6 (±0.2)x10{sup -3} g/m{sup 2}d while the forward dissolution rate for the laboratory-scale mineral product is 1.3 (±0.5)x10{sup -3} g/m{sup 2}d. (authors)

  14. Single-pass UV generation at 222.5?nm based on high-power GaN external cavity diode laser.

    PubMed

    Ruhnke, N; Müller, A; Eppich, B; Güther, R; Maiwald, M; Sumpf, B; Erbert, G; Tränkle, G

    2015-05-01

    We demonstrate a compact system for single-pass frequency doubling of high-power GaN diode laser radiation. The deep UV laser light at 222.5 nm is generated in a ?-BaB2O4 (BBO) crystal. A high-power GaN external cavity diode laser (ECDL) system in Littrow configuration with narrowband emission at 445 nm is used as pump source. At a pump power of 680 mW, a maximum UV power of 16 ?W in continuous-wave operation at 222.5 nm is achieved. This concept enables a compact diode laser-based system emitting in the deep ultraviolet spectral range. PMID:25927802

  15. Evaluation of a potential generator-produced PET tracer for cerebral perfusion imaging: Single-pass cerebral extraction measurements and imaging with radiolabeled Cu-PTSM

    SciTech Connect

    Mathias, C.J.; Welch, M.J.; Raichle, M.E.; Mintun, M.A.; Lich, L.L.; McGuire, A.H.; Zinn, K.R.; John, E.K.; Green, M.A. )

    1990-03-01

    Copper(II) pyruvaldehyde bis(N4-methylthiosemicarbazone) (Cu-PTSM), copper(II) pyruvaldehyde bis(N4-dimethylthiosemicarbazone) (Cu-PTSM2), and copper(II) ethylglyoxal bis(N4-methylthiosemicarbazone) (Cu-ETSM), have been proposed as PET tracers for cerebral blood flow (CBF) when labeled with generator-produced 62Cu (t1/2 = 9.7 min). To evaluate the potential of Cu-PTSM for CBF PET studies, baboon single-pass cerebral extraction measurements and PET imaging were carried out with the use of 67Cu (t1/2 = 2.6 days) and 64Cu (t1/2 = 12.7 hr), respectively. All three chelates were extracted into the brain with high efficiency. There was some clearance of all chelates in the 10-50-sec time frame and Cu-PTSM2 continued to clear. Cu-PTSM and Cu-ETSM have high residual brain activity. PET imaging of baboon brain was carried out with the use of (64Cu)-Cu-PTSM. For comparison with the 64Cu brain image, a CBF (15O-labeled water) image (40 sec) was first obtained. Qualitatively, the H2(15)O and (64Cu)-Cu-PTSM images were very similar; for example, a comparison of gray to white matter uptake resulted in ratios of 2.42 for H2(15)O and 2.67 for Cu-PTSM. No redistribution of 64Cu was observed in 2 hr of imaging, as was predicted from the single-pass study results. Quantitative determination of blood flow using Cu-PTSM showed good agreement with blood flow determined with H2(15)O. This data suggests that (62Cu)-Cu-PTSM may be a useful generator-produced radiopharmaceutical for blood flow studies with PET.

  16. High-power, high-repetition-rate performance characteristics of β-BaB₂O₄ for single-pass picosecond ultraviolet generation at 266 nm.

    PubMed

    Kumar, S Chaitanya; Casals, J Canals; Wei, Junxiong; Ebrahim-Zadeh, M

    2015-10-19

    We report a systematic study on the performance characteristics of a high-power, high-repetition-rate, picosecond ultraviolet (UV) source at 266 nm based on β-BaB2O4 (BBO). The source, based on single-pass fourth harmonic generation (FHG) of a compact Yb-fiber laser in a two-crystal spatial walk-off compensation scheme, generates up to 2.9 W of average power at 266 nm at a pulse repetition rate of ~80 MHz with a single-pass FHG efficiency of 35% from the green to UV. Detrimental issues such as thermal effects have been studied and confirmed by performing relevant measurements. Angular and temperature acceptance bandwidths in BBO for FHG to 266 nm are experimentally determined, indicating that the effective interaction length is limited by spatial walk-off and thermal gradients under high-power operation. The origin of dynamic color center formation due to two-photon absorption in BBO is investigated by measurements of intensity-dependent transmission at 266 nm. Using a suitable theoretical model, two-photon absorption coefficients as well as the color center densities have been estimated at different temperatures. The measurements show that the two-photon absorption coefficient in BBO at 266 nm is ~3.5 times lower at 200°C compared to that at room temperature. The long-term power stability as well as beam pointing stability is analyzed at different output power levels and focusing conditions. Using cylindrical optics, we have circularized the generated elliptic UV beam to a circularity of >90%. To our knowledge, this is the first time such high average powers and temperature-dependent two-photon absorption measurements at 266 nm are reported at repetition rates as high as ~80 MHz. PMID:26480467

  17. 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.

  18. 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.

  19. Heterodyne Interferometer Angle Metrology

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  20. Optical interferometer testbed

    NASA Technical Reports Server (NTRS)

    Blackwood, Gary H.

    1991-01-01

    Viewgraphs on optical interferometer testbed presented at the MIT Space Research Engineering Center 3rd Annual Symposium are included. Topics covered include: space-based optical interferometer; optical metrology; sensors and actuators; real time control hardware; controlled structures technology (CST) design methodology; identification for MIMO control; FEM/ID correlation for the naked truss; disturbance modeling; disturbance source implementation; structure design: passive damping; low authority control; active isolation of lightweight mirrors on flexible structures; open loop transfer function of mirror; and global/high authority control.

  1. Condor equatorial electrojet campaign: Radar results

    SciTech Connect

    Kudeki, E.; Fejer, B.G.; Farley, D.T.; Hanuise, C.

    1987-12-01

    A review of the experimental and theoretical background to the Condor equatorial electrojet compaign is followed by the presentation and discussion of VHF radar interferometer and HF radar backscatter data taken concurrently with two rocket in situ experiments reported in companion papers (Pfaff et al., this issue (a, b). Both experiments were conducted in strongly driven periods with the on-line radar interferometer displaying signatures of what has been interpreted in earlier radar work (Kudeki et al., 1982) as kilometer scale gradient drift waves. Low-frequency density fluctuations detected by in situ rocket sensors confirm the earlier interpretation. VHF radar/rocket data comparisons also indicate the existence of a turbulent layer in the upper portion of the daytime electrojet at about 108 km altitude driven purely by the two-stream instability. Nonlinear mode coupling of linearly growing two-stream waves to linearly damped 3-m vertical modes could account for the radar echoes scattered from this layer, which showed no indication of large-scale gradient drift waves. Nonlinear mode coupling may therefore compete with the wave-induced anomalous diffusion mechanism proposed recently by Sudan (1983) for the saturation of directly excited two-stream waves. Nighttime radar data show a bifurcated layer with the two parts having comparable echo strength but oppositely directed zonal drift velocities. The lower layer shows narrow backscatter spectra; the upper layer is characterized by kilometer scale waves and vertically propagating type 1 waves.

  2. Mesoscopic Interferometers for Electron Waves

    SciTech Connect

    Rohrlich, D.

    2005-09-15

    Mesoscopic interferometers are electronic analogues of optical interferometers, with 'quantum point contacts' playing the role of optical beam splitters. Mesoscopic analogues of two-slit, Mach-Zehnder and Fabry-Perot interferometers have been built. A fundamental difference between electron and photon interferometry is that electron interferometry is nonlocal.

  3. 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.

  4. 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…

  5. 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…

  6. Dual differential interferometer

    NASA Technical Reports Server (NTRS)

    Claus, R. O.; Turner, T. M. (inventors)

    1985-01-01

    A dual two-beam differential interferometer that measures both the amplitude and orientation of propagating, broadband surface acoustic waves is disclosed. Four beams are focused on a surface. The four reflected beams are separated into two pairs. The two pairs are detected to produce two signals that are used to compute amplitude and orientation.

  7. Rotatable shear plate interferometer

    DOEpatents

    Duffus, Richard C. (Livermore, CA)

    1988-01-01

    A rotatable shear plate interferometer comprises a transparent shear plate mounted obliquely in a tubular supporting member at 45.degree. with respect to its horizontal center axis. This tubular supporting member is supported rotatably around its center axis and a collimated laser beam is made incident on the shear plate along this center axis such that defocus in different directions can be easily measured.

  8. The Glacier and Land Ice Surface Topography Interferometer (GLISTIN): A Novel Ka-band Digitally Beamformed Interferometer

    NASA Technical Reports Server (NTRS)

    Moller, Delwyn K.; Heavey, Brandon; Hodges, Richard; Rengarajan, Sembiam; Rignot, Eric; Rogez, Francois; Sadowy, Gregory; Simard, Marc; Zawadzki, Mark

    2006-01-01

    The estimation of the mass balance of ice sheets and glaciers on Earth is a problem of considerable scientific and societal importance. A key measurement to understanding, monitoring and forecasting these changes is ice-surface topography, both for ice-sheet and glacial regions. As such NASA identified 'ice topographic mapping instruments capable of providing precise elevation and detailed imagery data for measurements on glacial scales for detailed monitoring of ice sheet, and glacier changes' as a science priority for the most recent Instrument Incubator Program (IIP) opportunities. Funded under this opportunity is the technological development for a Ka-Band (35GHz) single-pass digitally beamformed interferometric synthetic aperture radar (InSAR). Unique to this concept is the ability to map a significant swath impervious of cloud cover with measurement accuracies comparable to laser altimeters but with variable resolution as appropriate to the differing scales-of-interest over ice-sheets and glaciers.

  9. Single-Pass Flow-Through Test Elucidation of Weathering Behavior and Evaluation of Contaminant Release Models for Hanford Tank Residual Radioactive Waste

    SciTech Connect

    Cantrell, Kirk J.; Carroll, Kenneth C.; Buck, Edgar C.; Neiner, Doinita; Geiszler, Keith N.

    2013-01-01

    Contaminant release models are required to evaluate and predict long-term environmental impacts of even residual amounts of high-level radioactive waste after cleanup and closure of radioactively contaminated sites such as the DOE’s Hanford Site. More realistic and representative models have been developed for release of uranium, technetium, and chromium from Hanford Site tanks C-202, C-203, and C-103 residual wastes using data collected with a single-pass flow-through test (SPFT) method. These revised models indicate that contaminant release concentrations from these residual wastes will be considerably lower than previous estimates based on batch experiments. For uranium, a thermodynamic solubility model provides an effective description of uranium release, which can account for differences in pore fluid chemistry contacting the waste that could occur through time and as a result of different closure scenarios. Under certain circumstances in the SPFT experiments various calcium rich precipitates (calcium phosphates and calcite) form on the surfaces of the waste particles, inhibiting dissolution of the underlying uranium phases in the waste. This behavior was not observed in previous batch experiments. For both technetium and chromium, empirical release models were developed. In the case of technetium, release from all three wastes was modeled using an equilibrium Kd model. For chromium release, a constant concentration model was applied for all three wastes.

  10. In-situ intestinal rat perfusions for human Fabs prediction and BCS permeability class determination: Investigation of the single-pass vs. the Doluisio experimental approaches.

    PubMed

    Lozoya-Agullo, Isabel; Zur, Moran; Wolk, Omri; Beig, Avital; González-Álvarez, Isabel; González-Álvarez, Marta; Merino-Sanjuán, Matilde; Bermejo, Marival; Dahan, Arik

    2015-03-01

    Intestinal drug permeability has been recognized as a critical determinant of the fraction dose absorbed, with direct influence on bioavailability, bioequivalence and biowaiver. The purpose of this research was to compare intestinal permeability values obtained by two different intestinal rat perfusion methods: the single-pass intestinal perfusion (SPIP) model and the Doluisio (closed-loop) rat perfusion method. A list of 15 model drugs with different permeability characteristics (low, moderate, and high, as well as passively and actively absorbed) was constructed. We assessed the rat intestinal permeability of these 15 model drugs in both SPIP and the Doluisio methods, and evaluated the correlation between them. We then evaluated the ability of each of these methods to predict the fraction dose absorbed (Fabs) in humans, and to assign the correct BCS permeability class membership. Excellent correlation was obtained between the two experimental methods (r(2)=0.93). An excellent correlation was also shown between literature Fabs values and the predictions made by both rat perfusion techniques. Similar BCS permeability class membership was designated by literature data and by both SPIP and Doluisio methods for all compounds. In conclusion, the SPIP model and the Doluisio (closed-loop) rat perfusion method are both equally useful for obtaining intestinal permeability values that can be used for Fabs prediction and BCS classification. PMID:25595387

  11. Segmental-dependent membrane permeability along the intestine following oral drug administration: Evaluation of a triple single-pass intestinal perfusion (TSPIP) approach in the rat.

    PubMed

    Dahan, Arik; West, Brady T; Amidon, Gordon L

    2009-02-15

    In this paper we evaluate a modified approach to the traditional single-pass intestinal perfusion (SPIP) rat model in investigating segmental-dependent permeability along the intestine following oral drug administration. Whereas in the traditional model one single segment of the intestine is perfused, we have simultaneously perfused three individual segments of each rat intestine: proximal jejunum, mid-small intestine and distal ileum, enabling to obtain tripled data from each rat compared to the traditional model. Three drugs, with different permeabilities, were utilized to evaluate the model: metoprolol, propranolol and cimetidine. Data was evaluated in comparison to the traditional method. Metoprolol and propranolol showed similar P(eff) values in the modified model in all segments. Segmental-dependent permeability was obtained for cimetidine, with lower P(eff) in the distal parts. Similar P(eff) values for all drugs were obtained in the traditional method, illustrating that the modified model is as accurate as the traditional, throughout a wide range of permeability characteristics, whether the permeability is constant or segment-dependent along the intestine. Three-fold higher statistical power to detect segmental-dependency was obtained in the modified approach, as each subject serves as his own control. In conclusion, the Triple SPIP model can reduce the number of animals utilized in segmental-dependent permeability research without compromising the quality of the data obtained. PMID:19028572

  12. Comparison of the gravimetric, phenol red, and 14C-PEG-3350 methods to determine water absorption in the rat single-pass intestinal perfusion model.

    PubMed

    Sutton, S C; Rinaldi, M T; Vukovinsky, K E

    2001-01-01

    This study was undertaken to determine whether the gravimetric method provided an accurate measure of water flux correction and to compare the gravimetric method with methods that employ nonabsorbed markers (eg, phenol red and 14C-PEG-3350). Phenol red,14C-PEG-3350, and 4-[2-[[2-(6-amino-3-pyridinyl)-2-hydroxyethyl]amino]ethoxy]-, methyl ester, (R)-benzene acetic acid (Compound I) were co-perfused in situ through the jejunum of 9 anesthetized rats (single-pass intestinal perfusion [SPIP]). Water absorption was determined from the phenol red,14C-PEG-3350, and gravimetric methods. The absorption rate constant (ka) for Compound I was calculated. Both phenol red and 14C-PEG-3350 were appreciably absorbed, underestimating the extent of water flux in the SPIP model. The average +/- SD water flux microg/h/cm) for the 3 methods were 68.9 +/- 28.2 (gravimetric), 26.8 +/- 49.2 (phenol red), and 34.9 +/- 21.9 (14C-PEG-3350). The (average +/- SD) ka for Compound I (uncorrected for water flux) was 0.024 +/- 0.005 min(-1). For the corrected, gravimetric method, the average +/- SD was 0.031 +/- 0.001 min(-1). The gravimetric method for correcting water flux was as accurate as the 2 "nonabsorbed" marker methods. PMID:11741276

  13. A latent capacity of the C. elegans polycystins to disrupt sensory transduction is repressed by the single-pass ciliary membrane protein CWP-5

    PubMed Central

    Miller, Renee M.; Portman, Douglas S.

    2010-01-01

    SUMMARY Autosomal dominant polycystic kidney disease (ADPKD) results from loss-of-function mutations in PKD1 or PKD2. The products of these genes, the polycystins PC-1 and PC-2, form a transmembrane channel that is necessary for flow sensing by renal cilia. In C. elegans, the polycystin orthologs LOV-1 and PKD-2 function in sensory neurons that mediate male mating behavior. Here, we report that the novel single-pass membrane protein CWP-5 is necessary for polycystin signaling during the response step of mating behavior. As with the polycystins, CWP-5 localizes to neuronal cilia; this localization requires LOV-1. The response defect of cwp-5 mutants does not appear to result from disruption of ciliogenesis or polycystin localization. Instead, genetic and behavioral analyses indicate that CWP-5 represses a previously undescribed antagonistic effect of the polycystins on sensory function. Although cwp-5 does not have a primary-sequence ortholog in vertebrates, it has intriguing parallels with the autosomal recessive PKD gene FPC (also known as PKHD1). Together, this study identifies a new component of C. elegans polycystin signaling, demonstrates that the polycystins have a latent capacity to hinder sensory transduction, and suggests that aberrant functions of the polycystins could contribute to the pathogenesis of PKD. PMID:20223935

  14. The Antarctic Planet Interferometer

    NASA Technical Reports Server (NTRS)

    Swain, Mark R.; Walker, Christopher K.; Traub, Wesley A.; Storey, John W.; CoudeduForesto, Vincent; Fossat, Eric; Vakili, Farrok; Stark, Anthony A.; Lloyd, James P.; Lawson, Peter R.; Burrows, Adam S.; Ireland, Michael; Millan-Gabet, Rafael; vanBelle, Gerard T.; Lane, Benjamin; Vasisht, Gautam; Travouillon, Tony

    2004-01-01

    The Antarctic Planet Interferometer is an instrument concept designed to detect and characterize extrasolar planets by exploiting the unique potential of the best accessible site on earth for thermal infrared interferometry. High-precision interferometric techniques under development for extrasolar planet detection and characterization (differential phase, nulling and astrometry) all benefit substantially from the slow, low-altitude turbulence, low water vapor content, and low temperature found on the Antarctic plateau. At the best of these locations, such as the Concordia base being developed at Dome C, an interferometer with two-meter diameter class apertures has the potential to deliver unique science for a variety of topics, including extrasolar planets, active galactic nuclei, young stellar objects, and protoplanetary disks.

  15. Multipulsed dynamic moire interferometer

    DOEpatents

    Deason, Vance A. (Idaho Falls, ID)

    1991-01-01

    An improved dynamic moire interferometer comprised of a lasing medium providing a plurality of beams of coherent light, a multiple q-switch producing multiple trains of 100,000 or more pulses per second, a combining means collimating multiple trains of pulses into substantially a single train and directing beams to specimen gratings affixed to a test material, and a controller, triggering and sequencing the emission of the pulses with the occurrence and recording of a dynamic loading event.

  16. Cold Lithium Atom Interferometer

    NASA Astrophysics Data System (ADS)

    Cassella, Kayleigh; Copenhaver, Eric; Lai, Chen; Hamilton, Paul; Estey, Brian; Feng, Yanying; Mueller, Holger

    2015-05-01

    Atom interferometers often use heavy alkali atoms such as rubidium or cesium. In contrast, interferometry with light atoms offers a larger recoil velocity and recoil energy, yielding a larger interference signal. This would allow for sensitive measurements of the fine structure constant, gravity gradients and spatially varying potentials. We have built the first light-pulse cold-atom interferometer with lithium in a Mach-Zehnder geometry based on short (100 ns), intense (2.5 W/cm2) pulses. We initially capture approximately 107 lithium atoms at a temperature of about 300 ?K in a magneto-optical trap. To perform interferometry, we couple the F = 1 and F = 2 hyperfine levels of the ground state with a sequence of two-photon Raman transitions, red-detuned from lithium's unresolved 2P3/2 state. Cold lithium atoms offer a broad range of new possibilities for atom interferometry including a large recoil velocity and a fermionic and bosonic isotope. Lithium's isotopes also allow for independent measurements of gravity thus constraining the equivalence principle violations predicted by the Standard-Model Extension. In the near future, we plan to perform a recoil measurement using a Ramsey-Bordé interferometer.

  17. The Keck Interferometer

    NASA Astrophysics Data System (ADS)

    Colavita, M. M.; Wizinowich, P. L.; Akeson, R. L.; Ragland, S.; Woillez, J. M.; Millan-Gabet, R.; Serabyn, E.; Abajian, M.; Acton, D. S.; Appleby, E.; Beletic, J. W.; Beichman, C. A.; Bell, J.; Berkey, B. C.; Berlin, J.; Boden, A. F.; Booth, A. J.; Boutell, R.; Chaffee, F. H.; Chan, D.; Chin, J.; Chock, J.; Cohen, R.; Cooper, A.; Crawford, S. L.; Creech-Eakman, M. J.; Dahl, W.; Eychaner, G.; Fanson, J. L.; Felizardo, C.; Garcia-Gathright, J. I.; Gathright, J. T.; Hardy, G.; Henderson, H.; Herstein, J. S.; Hess, M.; Hovland, E. E.; Hrynevych, M. A.; Johansson, E.; Johnson, R. L.; Kelley, J.; Kendrick, R.; Koresko, C. D.; Kurpis, P.; Le Mignant, D.; Lewis, H. A.; Ligon, E. R.; Lupton, W.; McBride, D.; Medeiros, D. W.; Mennesson, B. P.; Moore, J. D.; Morrison, D.; Nance, C.; Neyman, C.; Niessner, A.; Paine, C. G.; Palmer, D. L.; Panteleeva, T.; Papin, M.; Parvin, B.; Reder, L.; Rudeen, A.; Saloga, T.; Sargent, A.; Shao, M.; Smith, B.; Smythe, R. F.; Stomski, P.; Summers, K. R.; Swain, M. R.; Swanson, P.; Thompson, R.; Tsubota, K.; Tumminello, A.; Tyau, C.; van Belle, G. T.; Vasisht, G.; Vause, J.; Vescelus, F.; Walker, J.; Wallace, J. K.; Wehmeier, U.; Wetherell, E.

    2013-10-01

    The Keck Interferometer (KI) combined the two 10 m W. M. Keck Observatory telescopes on Mauna Kea, Hawaii, as a long-baseline near- and mid-infrared interferometer. Funded by NASA, it operated from 2001 until 2012. KI used adaptive optics on the two Keck telescopes to correct the individual wavefronts, as well as active fringe tracking in all modes for path-length control, including the implementation of cophasing to provide long coherent integration times. KI implemented high sensitivity fringe-visibility measurements at H (1.6 μm), K (2.2 μm), and L (3.8 μm) bands, and nulling measurements at N band (10 μm), which were used to address a broad range of science topics. Supporting these capabilities was an extensive interferometer infrastructure and unique instrumentation, including some additional functionality added as part of the NSF-funded ASTRA program. This paper provides an overview of the instrument architecture and some of the key design and implementation decisions, as well as a description of all of the key elements and their configuration at the end of the project. The objective is to provide a view of KI as an integrated system, and to provide adequate technical detail to assess the implementation. Included is a discussion of the operational aspects of the system, as well as of the achieved system performance. Finally, details on V2 calibration in the presence of detector nonlinearities as applied in the data pipeline are provided.

  18. 5.7??W cw single-frequency laser at 671??nm by single-pass second harmonic generation of a 17.2??W injection-locked 1342??nm Nd?:?YVO4 ring laser using periodically poled MgO?:?LiNbO3.

    PubMed

    Koch, Peter; Ruebel, Felix; Bartschke, Juergen; L'huillier, Johannes A

    2015-11-20

    We demonstrate a continuous wave single-frequency laser at 671.1 nm based on a high-power 888 nm pumped Nd:YVO4 ring laser at 1342.2 nm. Unidirectional operation of the fundamental ring laser is achieved with the injection-locking technique. A Nd:YVO4 microchip laser serves as the injecting seed source, providing a tunable single-frequency power of up to 40 mW. The ring laser emits a single-frequency power of 17.2 W with a Gaussian beam profile and a beam propagation factor of M2<1.1. A 60-mm-long periodically poled MgO-doped LiNbO3 crystal is used to generate the second harmonic in a single-pass scheme. Up to 5.7 W at 671.1 nm with a Gaussian shaped beam profile and a beam propagation factor of M2<1.2 are obtained, which is approximately twice the power of previously reported lasers. This work opens possibilities in cold atoms experiments with lithium, allowing the use of larger ensembles in magneto-optical traps or higher diffraction orders in atomic beam interferometers. PMID:26836563

  19. 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.

  20. Lamivudine permeability study: a comparison between PAMPA, ex vivo and in situ Single-Pass Intestinal Perfusion (SPIP) in rat jejunum.

    PubMed

    Reis, J M; Dezani, A B; Pereira, T M; Avdeef, A; Serra, C H R

    2013-03-12

    In order to reach the bloodstream and thus the target receptor, an orally-administered drug must first cross the intestinal barrier, which can occur via a paracellular, passive transcellular, or carrier-mediated uptake and/or efflux process (active or concentration gradient-driven). Our work aimed to explore the transport mechanism of the antiretroviral lamivudine (deoxycytidine nucleoside analogue), using a three-part strategy: in vitro, an ex vivo and an in situ method, represented by PAMPA, rat jejunum patches and rat Single Pass Intestinal Perfusion (SPIP), respectively. The determined permeability coefficients were compared with those from a published Caco-2 and MDCK study. Computational prediction of human jejunal permeability was explored, using various non-human permeability coefficients as descriptors. The ex vivo technique was performed in Franz-type diffusion cells, mounted with male Wistar rat jejunum segment patches. PAMPA was performed with an acceptor solution simulating the binding of serum proteins, an artificial membrane impregnated with egg lecithin/cholesterol and a gradient of pH between donor and acceptor solutions. The SPIP was conducted by proximal jejunum cannulation and drug perfusion in a constant flow rate of 0.2 mL/min. The outcomes of our studies showed the following predicted pattern for lamivudine effective jejunal permeability: P(eff)(exvivoA>B)>P(eff)(SPIP)>P(eff)(exvivo B>A)>P(eff)(Caco-2)?P(eff)(MDCK)?P(eff)(PAMPA), strongly suggesting that this compound has carrier-mediated uptake as its dominant transport mechanism. Notwithstanding, Caco-2 cells may indicate an under-expression of uptake transporters and possibly an over-expression efflux transporters, compared to that found in the rat jejunum. PMID:23298578

  1. The shuttle topography mission

    NASA Technical Reports Server (NTRS)

    Farr, T. G.; Kobrick, M.

    2000-01-01

    This mission was designed to use a single-pass radar interferometer to produce a digital elevation model (DEM) of the Earth's land surface between about 60 degrees north and 56 degrees south latitude.

  2. 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.

  3. Atom-Light Hybrid Interferometer

    NASA Astrophysics Data System (ADS)

    Chen, Bing; Qiu, Cheng; Chen, Shuying; Guo, Jinxian; Chen, L. Q.; Ou, Z. Y.; Zhang, Weiping

    2015-07-01

    A new type of hybrid atom-light interferometer is demonstrated with atomic Raman amplification processes replacing the beam splitting elements in a traditional interferometer. This nonconventional interferometer involves correlated optical and atomic waves in the two arms. The correlation between atoms and light developed with the Raman process makes this interferometer different from conventional interferometers with linear beam splitters. It is observed that the high-contrast interference fringes are sensitive to the optical phase via a path change as well as the atomic phase via a magnetic field change. This new atom-light correlated hybrid interferometer is a sensitive probe of the atomic internal state and should find wide applications in precision measurement and quantum control with atoms and photons.

  4. Atom-Light Hybrid Interferometer.

    PubMed

    Chen, Bing; Qiu, Cheng; Chen, Shuying; Guo, Jinxian; Chen, L Q; Ou, Z Y; Zhang, Weiping

    2015-07-24

    A new type of hybrid atom-light interferometer is demonstrated with atomic Raman amplification processes replacing the beam splitting elements in a traditional interferometer. This nonconventional interferometer involves correlated optical and atomic waves in the two arms. The correlation between atoms and light developed with the Raman process makes this interferometer different from conventional interferometers with linear beam splitters. It is observed that the high-contrast interference fringes are sensitive to the optical phase via a path change as well as the atomic phase via a magnetic field change. This new atom-light correlated hybrid interferometer is a sensitive probe of the atomic internal state and should find wide applications in precision measurement and quantum control with atoms and photons. PMID:26252684

  5. Infrared lateral shearing interferometers

    NASA Astrophysics Data System (ADS)

    Kwon, O.

    1980-04-01

    Recently IR interferometry has received much attention for its special capabilities of testing IR materials, diamond-turned metal mirrors, deep aspherics, unpolished rough surface optics, and other unconventional optics. A CW CO2 laser is used as a coherent light source at 10.6 microns, and germanium and zinc selenide optics are used for lenses and beam splitters. A pyroelectric vidicon (PEV) detects the modulated interference pattern through a TV monitor and video recorder-player. This paper presents three methods of IR lateral shear interferometry using (1) a germanium plane-parallel plate, (2) a Ronchi ruling, and (3) a double-grating lateral shear interferometer.

  6. 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.

  7. Mark-3 interferometer

    NASA Astrophysics Data System (ADS)

    Staelin, David H.; Barrett, John W.; Kim, Edward J.; Stuart, Howard R.

    1989-09-01

    The development and testing of the Mark-3 stellar interferometer is considered. The instrument employs a two color technique to reduce position errors due to atmospheric turbulence, and can operate with four possible baseline configurations ranging from 9 to 20 meters. Despite its function as a technology development platform, it is also capable of stellar separation and stellar diameter measurements with nearly unprecedented accuracy and sensitivity. The major contributions are the development of a dispersed-fringe group delay measurement system which can boost the system sensitivity by several stellar magnitudes, and the initial stages of development of an infrared capability, which should increase the future scientific interest of the facility.

  8. The Stress-Relief Cracking Susceptibility of a New Ferritic Steel - Part I: Single-Pass Heat-Affected Zone Simulations

    SciTech Connect

    NAWROCKI,J.G.; DUPONT,J.N.; ROBINO,CHARLES V.; MARDER,A.R.

    1999-12-15

    The stress-relief cracking susceptibility of single-pass welds in a new ferritic steel, HCM2S, has been evaluated and compared to 2.25Cr-1Mo steel using Gleeble techniques. Simulated coarse-grained heat-affected zones (CGHAZ) were produced under a range of energy inputs and tested at various post-weld heat treatment (PWHT) temperatures. Both alloys were tested at a stress of 325 MPa. The 2.25 Cr-1Mo steel was also tested at 270 MPa to normalize for the difference in yield strength between the two materials. Light optical and scanning electron microscopy were used to characterize the CGHAZ microstructure. The ''as-welded'' CGHAZ of each alloy consisted of lath martensite or bainite and had approximately equal prior austenite grain sizes. The as-welded hardness of the 2.25Cr-1Mo steel CGHAZ was significantly higher than that of the HCM2S alloy. Over the range studied energy input had no effect on the as-welded microstructure or hardness of either alloy. The energy input also had no effect on the stress-relief cracking susceptibility of either material. Both alloys failed intergranularly along prior austenite grain boundaries under all test conditions. The 2.25Cr-1Mo steel samples experienced significant macroductility and some microductility when tested at 325 MPa. The ductility decreased significantly when tested at 270 MPa but was still higher that than of HCM2S at each test condition. The time to failure decreased with increasing PWHT Temperature for each material. There was no significant difference in the times to failure between the two materials. Varying energy input and stress had no effect on the time-to failure. The ductility, as measured by reduction in are% increased with increasing PWHT temperature for 2.25 Cr-1Mo steel tested at both stresses. However, PWHT temperature had no effect on the ductility of HCM2S. The hardness of the CGHAZ for 2.25Cr-1Mo steel decreased significantly after PWHT, but remained constant for HCM2S. The differences in stress-relief cracking response are discussed in terms of the differences in composition and expected carbide precipitation sequence for each alloy during PWHT.

  9. Wavelength independent interferometer

    NASA Technical Reports Server (NTRS)

    Hochberg, Eric B. (Inventor); Page, Norman A. (Inventor)

    1991-01-01

    A polychromatic interferometer utilizing a plurality of parabolic reflective surfaces to properly preserve the fidelity of light wavefronts irrespective of their wavelengths as they pass through the instrument is disclosed. A preferred embodiment of the invention utilizes an optical train which comprises three off-axis parabolas arranged in conjunction with a beam-splitter and a reference mirror to form a Twyman-Green interferometer. An illumination subsystem is provided and comprises a pair of lasers at different preselected wavelengths in the visible spectrum. The output light of the two lasers is coaxially combined by means of a plurality of reflectors and a grating beam combiner to form a single light source at the focal point of the first parabolic reflection surface which acts as a beam collimator for the rest of the optical train. By using visible light having two distinct wavelengths, the present invention provides a long equivalent wavelength interferogram which operates at visible light wherein the effective wavelength is equal to the product of the wavelengths of the two laser sources divided by their difference in wavelength. As a result, the invention provides the advantages of what amounts to long wavelength interferometry but without incurring the disadvantage of the negligible reflection coefficient of the human eye to long wavelength frequencies which would otherwise defeat any attempt to form an interferogram at that low frequency using only one light source.

  10. Planetary Radar

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1992-01-01

    Planetary radar astronomy is the study of solar system entities (the moon, asteroids, and comets, as well as the major planets and their satellites and ring systems) by transmitting radio signals towards a target and receiving and analyzing the echoes.

  11. Radio Seeing Monitor Interferometer

    NASA Astrophysics Data System (ADS)

    Hiriart, David; Valdez, Jorge; Zaca, Placido; Medina, José L.

    2002-10-01

    A two-element interferometer for monitoring atmospheric phase fluctuations (radio seeing) is presented; this uses the unmodulated beacon signal at 11.715 GHz from a geostationary satellite. The system measures phase differences on the signal received by two small antennas separated by 50 m. The system incorporates the best features from previous designs: a heterodyne phase-lock receiver and an IQ demodulator system. Phase fluctuations measured at this frequency may be extrapolated to millimetric and submillimetric wavelengths since the atmosphere is not dispersive at these frequencies. The instrument has been tested at the Observatory San Pedro Martir (Mexico) at 2800 m above sea level. The final destination of the instrument is Cerro la Negra (Mexico), where the Large Millimeter Telescope is under construction, at an altitude of 4600 m.

  12. Mark 3 interferometer

    NASA Astrophysics Data System (ADS)

    Staelin, David H.; Barrett, John W.; Kim, Edward J.; Stuart, Howard R.

    1990-01-01

    This work is a continuation of that begun under Naval Research Laboratory Contracts N00014-84-C-2082 and N00014-86-C-2114. All three of these contracts involved participation in the development and testing of the Mark-III stellar interferometer at the Mount Wilson Observatory in California. This instrument employs a two-color technique to reduce position errors due to atmospheric turbulence, and can operate with four possible baseline configurations ranging from 9 to 20 meters. Despite its function as a technology development platform, it is also capable of stellar separation and stellar diameter measurements with nearly unprecedented accuracy and sensitivity. The major contributions of this work are the development of a dispersed-fringe group delay measurement system which can boost the system sensitivity be several stellar magnitudes, and the initial stages of development of an infrared capability, which should increase the future scientific interest of the facility.

  13. Heterodyne imaging speckle interferometer

    NASA Astrophysics Data System (ADS)

    Wang, Shengjia; Gao, Zhan; Feng, Ziang; Zhang, Xiaoqiong; Yang, Dong; Yuan, Hao

    2015-03-01

    A heterodyne imaging speckle interferometer coupled with lithium niobate is developed for whole field dynamic deformation imaging. In this device, the carrier frequency is introduced by the dual-transverse linear electro-optic effect. It is electrically controlled within a large range, which is twice the angular velocity of the driving alternating electric fields. By setting the angular velocity, the carrier frequency can fit most of area-array detectors, making it feasible to achieve whole field real time imaging. By using temporal evolution of the light intensity in heterodyne interferometry, the temporal intensity analysis method is employed to extract the deformation at each pixel dynamically. The principle and system configuration are described. The preliminary experiment is conducted with a cantilever beam and the results are compared with theoretical simulations to validate the proposed approach.

  14. 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.

  15. The VLT Interferometer

    NASA Astrophysics Data System (ADS)

    Richichi, A.

    2008-07-01

    The ESO Very Large Telescope Interferometer (VLTI) is arguably the most powerful optical interferometric facility available at present. In addition to the wide choice of baselines and the light collecting power of its 8.2 m and 1.8 m telescopes, the VLTI also offers a smooth and user-friendly operation which makes interferometry accessible to any astronomer and covers a wide range of scientific applications. Behind the routine scientific operations, however, the VLTI is in constant evolution. I will present some of the technological and instrumental improvements which are planned for the near and mid-term future, and discuss their implications for astrometry in particular. Among them, the PRIMA facility and the proposed GRAVITY instrument are designed to reach the level of 10 microarcseconds in the near-infrared.

  16. MIT's interferometer CST testbed

    NASA Technical Reports Server (NTRS)

    Hyde, Tupper; Kim, ED; Anderson, Eric; Blackwood, Gary; Lublin, Leonard

    1990-01-01

    The MIT Space Engineering Research Center (SERC) has developed a controlled structures technology (CST) testbed based on one design for a space-based optical interferometer. The role of the testbed is to provide a versatile platform for experimental investigation and discovery of CST approaches. In particular, it will serve as the focus for experimental verification of CSI methodologies and control strategies at SERC. The testbed program has an emphasis on experimental CST--incorporating a broad suite of actuators and sensors, active struts, system identification, passive damping, active mirror mounts, and precision component characterization. The SERC testbed represents a one-tenth scaled version of an optical interferometer concept based on an inherently rigid tetrahedral configuration with collecting apertures on one face. The testbed consists of six 3.5 meter long truss legs joined at four vertices and is suspended with attachment points at three vertices. Each aluminum leg has a 0.2 m by 0.2 m by 0.25 m triangular cross-section. The structure has a first flexible mode at 31 Hz and has over 50 global modes below 200 Hz. The stiff tetrahedral design differs from similar testbeds (such as the JPL Phase B) in that the structural topology is closed. The tetrahedral design minimizes structural deflections at the vertices (site of optical components for maximum baseline) resulting in reduced stroke requirements for isolation and pointing of optics. Typical total light path length stability goals are on the order of lambda/20, with a wavelength of light, lambda, of roughly 500 nanometers. It is expected that active structural control will be necessary to achieve this goal in the presence of disturbances.

  17. MIT's interferometer CST testbed

    NASA Astrophysics Data System (ADS)

    Hyde, Tupper; Kim, Ed; Anderson, Eric; Blackwood, Gary; Lublin, Leonard

    1990-12-01

    The MIT Space Engineering Research Center (SERC) has developed a controlled structures technology (CST) testbed based on one design for a space-based optical interferometer. The role of the testbed is to provide a versatile platform for experimental investigation and discovery of CST approaches. In particular, it will serve as the focus for experimental verification of CSI methodologies and control strategies at SERC. The testbed program has an emphasis on experimental CST--incorporating a broad suite of actuators and sensors, active struts, system identification, passive damping, active mirror mounts, and precision component characterization. The SERC testbed represents a one-tenth scaled version of an optical interferometer concept based on an inherently rigid tetrahedral configuration with collecting apertures on one face. The testbed consists of six 3.5 meter long truss legs joined at four vertices and is suspended with attachment points at three vertices. Each aluminum leg has a 0.2 m by 0.2 m by 0.25 m triangular cross-section. The structure has a first flexible mode at 31 Hz and has over 50 global modes below 200 Hz. The stiff tetrahedral design differs from similar testbeds (such as the JPL Phase B) in that the structural topology is closed. The tetrahedral design minimizes structural deflections at the vertices (site of optical components for maximum baseline) resulting in reduced stroke requirements for isolation and pointing of optics. Typical total light path length stability goals are on the order of lambda/20, with a wavelength of light, lambda, of roughly 500 nanometers. It is expected that active structural control will be necessary to achieve this goal in the presence of disturbances.

  18. The Keck Interferometer Nuller

    NASA Technical Reports Server (NTRS)

    Serabyn, E.; Mennesson, B.; Colavita, M. M.; Koresko, C.; Kuchner, M. J.

    2012-01-01

    The Keck Interferometer Nuller (KIN), the first operational separated-aperture infrared nulling interferometer, was designed to null the mid-infrared emission from nearby stars so as to ease the measurement of faint circumstellar emission. This paper describes the basis of the KIN's four-beam, two-stage measurement approach and compares it 10 the simpler case of a two-beam nuller. In the four-beam KIN system, the starlight is first nulled in a pair of nullers operating on parallel 85 m Keck-Keck baselines, after which "cross-combination" on 4 m baselines across the Keck apertures is used to modulate and detect residual coherent off-axis emission. Comparison to the constructive itellar fringe provides calibration. The response to an extended source is similar in the two cases, except that the four-beam response includes a term due to the visibility of the source on the cross-combiner baseline-a small effect for relatively compact sources. The characteristics of the dominant null depth errors are also compared for the two cases. In the two-beam nuller, instrumental imperfections and asymmetries lead to a series of quadratic, positivedefinite null leakage terms. For the four-beam nuller, the leakage is instead a series of correlation cross-tenns combining corresponding errors in each of the two nullers, which contribute offsets only to the extent that these errors are correlated on the timescale of the measurement. This four-beam architecture has allowed a significant (approx. order of magnitude) improvement in mid-infrared long-baseline fringe-visibility accuracies.

  19. The Keck Interferometer Nuller

    NASA Astrophysics Data System (ADS)

    Serabyn, E.; Mennesson, B.; Colavita, M. M.; Koresko, C.; Kuchner, M. J.

    2012-03-01

    The Keck Interferometer Nuller (KIN), the first operational separated-aperture infrared nulling interferometer, was designed to null the mid-infrared emission from nearby stars so as to ease the measurement of faint circumstellar emission. This paper describes the basis of the KIN's four-beam, two-stage measurement approach and compares it to the simpler case of a two-beam nuller. In the four-beam KIN system, the starlight is first nulled in a pair of nullers operating on parallel 85 m Keck-Keck baselines, after which "cross-combination" on 4 m baselines across the Keck apertures is used to modulate and detect residual coherent off-axis emission. Comparison to the constructive stellar fringe provides calibration. The response to an extended source is similar in the two cases, except that the four-beam response includes a term due to the visibility of the source on the cross-combiner baseline—a small effect for relatively compact sources. The characteristics of the dominant null depth errors are also compared for the two cases. In the two-beam nuller, instrumental imperfections and asymmetries lead to a series of quadratic, positive-definite null leakage terms. For the four-beam nuller, the leakage is instead a series of correlation cross-terms combining corresponding errors in each of the two nullers, which contribute offsets only to the extent that these errors are correlated on the timescale of the measurement. This four-beam architecture has allowed a significant (~order of magnitude) improvement in mid-infrared long-baseline fringe-visibility accuracies.

  20. 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.

  1. 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.

  2. Terrestrial quadstatic interferometric radar observations of Mars

    NASA Astrophysics Data System (ADS)

    Larsen, Kristopher William

    2003-12-01

    The goal of this research was to develop the techniques to map the surface of Mars using a terrestrial quadstatic radar interferometer. A series of X-band (3.5 centimeter) delay-Doppler radar observations surrounding the 2001 Mars opposition provided a data-set with which to develop the quadstatic technique while exploring one of Mars' unique geologic terrains, the hematite region of Terra Meridiani. Using four telescopes of the Goldstone Deep Space Communications Complex in the interferometer array allowed for the robust solution of the ambiguity inherent to the delay-Doppler radar technique. The analysis of the collected data focused on observations of Terra Meridiani. The Mars Global Surveyor spacecraft detected significant concentrations of crystalline gray hematite in Terra Meridiani, prompting its selection as one of the landing sites for the 2003 Mars Exploration Rover mission. Both one-dimensional radar profiles that cross the hematite deposits, and two- dimensional maps of the radar properties of the surface were produced and analyzed. Two observations produced one-dimensional profiles of the Hagfors' scattering parameters across the hematite deposits. Both show enhanced Fresnel reflection coefficients coincident with the detected hematite deposits. Analysis of the enhancement provides estimates of surface properties that are testable by the Mars Exploration Rover upon its arrival in 2004. Derived roughness for the landing site ellipse show a very smooth surface on the scale of a meter, implying a highly traversable site for the rover. The highest resolution maps of the Martian radar backscatter coefficient, five kilometers per pixel, are produced for northern Terra Meridiani using the quadstatic interferometric techniques herein developed. Craters and the floor of Ares Valles are anti-correlated with the thermal inertia and larger scale roughness calculated from the Mars Orbiter Laser Altimeter. The addition of high-resolution radar data provides additional information about the surface characteristics of Mars that can be used to decipher the planet's geologic history.

  3. Scanning heterodyne optical interferometers

    NASA Astrophysics Data System (ADS)

    Riza, Nabeel A.

    1996-07-01

    Compact, high performance, scanning heterodyne optical interferometers are introduced for interferometric phase-based measurement applications. The novel, in-line, almost common-path optical interferometer design offers robustness to externally induced phase noise via mechanical vibrations, thermal effects, and other environmental effects. Novel instrument designs are introduced for both transmissive and reflective interferometry. These instruments use acousto-optic devices or Bragg cells to implement rapid (e.g., <50 ?s/scan spot) optical scanning of the test medium. Although the read optical beam scans a given test region, the double Bragg diffraction optical design of the instrument makes the final interfering output beams stationary on the two high speed photodetectors used for radio frequency signal generation via heterodyne detection. One photodetector acts as the fixed phase reference, while the other fixed photodetector picks up the test medium phase information as the optical beam scans the test region. The transmissive design instrument is built in the laboratory using flint glass Bragg cells. A typical 120 MHz heterodyne detected signal output had a carrier-to-noise ratio of 108.9 dBc/Hz measured at a +160 kHz offset using a spectrum analyzer resolution bandwidth of 30 kHz. The corresponding single-sideband phase noise was estimated at -101.57 dBc/Hz at 160 kHz offset. The measured instrument radio frequency dynamic range was ˜60 dB or an equivalent of 30 dB optical dynamic range, with a 1/1000 of a fringe cycle phase measurement accuracy. Test medium optical phase mapping was successfully tested with the instrument using a large area, 6 ?m thick, birefringent-mode nematic liquid crystal cell. Our instrument allows the use of high continuous wave or peak power, broad spectral linewidth, coherent light sources. The instrument can have a high 50% optical power efficiency. High speed two-dimensional optical scanning of a test medium is possible with our instrument by using a fixed one-dimensional output high speed detector array, or via the use of high speed nonmechanical electro-optic deflectors.

  4. Balloon Exoplanet Nulling Interferometer (BENI)

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Clampin, Mark; Woodruff, Robert A.; Vasudevan, Gopal; Ford, Holland; Petro, Larry; Herman, Jay; Rinehart, Stephen; Carpenter, Kenneth; Marzouk, Joe

    2009-01-01

    We evaluate the feasibility of using a balloon-borne nulling interferometer to detect and characterize exosolar planets and debris disks. The existing instrument consists of a 3-telescope Fizeau imaging interferometer with 3 fast steering mirrors and 3 delay lines operating at 800 Hz for closed-loop control of wavefront errors and fine pointing. A compact visible nulling interferometer is under development which when coupled to the imaging interferometer would in-principle allow deep suppression of starlight. We have conducted atmospheric simulations of the environment above 100,000 feet and believe balloons are a feasible path forward towards detection and characterization of a limited set of exoplanets and their debris disks. Herein we will discuss the BENI instrument, the balloon environment and the feasibility of such as mission.

  5. Compact portable diffraction moire interferometer

    DOEpatents

    Deason, Vance A. (Shelley, ID); Ward, Michael B. (Idaho Falls, ID)

    1989-01-01

    A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observation means including film and video cameras may be used to view and record the resultant fringe patterns.

  6. Compact portable diffraction moire interferometer

    DOEpatents

    Deason, V.A.; Ward, M.B.

    1988-05-23

    A compact and portable moire interferometer used to determine surface deformations of an object. The improved interferometer is comprised of a laser beam, optical and fiber optics devices coupling the beam to one or more evanescent wave splitters, and collimating lenses directing the split beam at one or more specimen gratings. Observations means including film and video cameras may be used to view and record the resultant fringe patterns. 7 figs.

  7. Surface profiling interferometer

    DOEpatents

    Takacs, Peter Z. (P.O. Box 385, Upton, NY 11973); Qian, Shi-Nan (Hefei Synchrotron Radiation Laboratory, University of Science and, Hefei, Anhui, CN)

    1989-01-01

    The design of a long-trace surface profiler for the non-contact measurement of surface profile, slope error and curvature on cylindrical synchrotron radiation (SR) mirrors. The optical system is based upon the concept of a pencil-beam interferometer with an inherent large depth-of-field. The key feature of the optical system is the zero-path-difference beam splitter, which separates the laser beam into two colinear, variable-separation probe beams. A linear array detector is used to record the interference fringe in the image, and analysis of the fringe location as a function of scan position allows one to reconstruct the surface profile. The optical head is mounted on an air bearing slide with the capability to measure long aspheric optics, typical of those encountered in SR applications. A novel feature of the optical system is the use of a transverse "outrigger" beam which provides information on the relative alignment of the scan axis to the cylinder optic symmetry axis.

  8. A quantum scattering interferometer.

    PubMed

    Hart, Russell A; Xu, Xinye; Legere, Ronald; Gibble, Kurt

    2007-04-19

    The collision of two ultracold atoms results in a quantum mechanical superposition of the two possible outcomes: each atom continues without scattering, and each atom scatters as an outgoing spherical wave with an s-wave phase shift. The magnitude of the s-wave phase shift depends very sensitively on the interaction between the atoms. Quantum scattering and the underlying phase shifts are vitally important in many areas of contemporary atomic physics, including Bose-Einstein condensates, degenerate Fermi gases, frequency shifts in atomic clocks and magnetically tuned Feshbach resonances. Precise experimental measurements of quantum scattering phase shifts have not been possible because the number of scattered atoms depends on the s-wave phase shifts as well as the atomic density, which cannot be measured precisely. Here we demonstrate a scattering experiment in which the quantum scattering phase shifts of individual atoms are detected using a novel atom interferometer. By performing an atomic clock measurement using only the scattered part of each atom's wavefunction, we precisely measure the difference of the s-wave phase shifts for the two clock states in a density-independent manner. Our method will enable direct and precise measurements of ultracold atom-atom interactions, and may be used to place stringent limits on the time variations of fundamental constants. PMID:17443182

  9. Michelson Interferometer (MINT)

    NASA Astrophysics Data System (ADS)

    Lacis, Andrew; Carlson, Barbara

    1993-09-01

    MINT is a Michelson interferometer designed to measure the thermal emission from the earth at high spectral resolution (2/cm) over a broad spectral range (250-1700/cm, 6-40 mu m) with contiguous 3-pixel wide (12 mrad, 8 km field of view) along-track sampling. MINT is particularly well suited for monitoring cloud properties (cloud cover, effective temperature, optical thickness, ice/water phase, and effective particle size) both day and night, as well as tropospheric water vapor, ozone, and temperature. The key instrument characteristics that make MINT ideally suited for decadal monitoring purposes are: high wavelength to wavelength precision across the full IR spectrum with high spectral resolution; space-proven long-term durability and calibration stability; and small size, low cost, low risk instrument incorporating the latest detector and electronics technology. MINT also incorporates simplicity in design and operation by utilizing passively cooled DTGS detectors and nadir viewing geometry (with target motion compensation). MINT measurement objectives, instrument characteristics, and key advantages are summarized in this paper.

  10. Michelson Interferometer (MINT)

    NASA Technical Reports Server (NTRS)

    Lacis, Andrew; Carlson, Barbara

    1993-01-01

    MINT is a Michelson interferometer designed to measure the thermal emission from the earth at high spectral resolution (2/cm) over a broad spectral range (250-1700/cm, 6-40 mu m) with contiguous 3-pixel wide (12 mrad, 8 km field of view) along-track sampling. MINT is particularly well suited for monitoring cloud properties (cloud cover, effective temperature, optical thickness, ice/water phase, and effective particle size) both day and night, as well as tropospheric water vapor, ozone, and temperature. The key instrument characteristics that make MINT ideally suited for decadal monitoring purposes are: high wavelength to wavelength precision across the full IR spectrum with high spectral resolution; space-proven long-term durability and calibration stability; and small size, low cost, low risk instrument incorporating the latest detector and electronics technology. MINT also incorporates simplicity in design and operation by utilizing passively cooled DTGS detectors and nadir viewing geometry (with target motion compensation). MINT measurement objectives, instrument characteristics, and key advantages are summarized in this paper.

  11. 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.

  12. 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

  13. Anomalous dynamic backaction in interferometers

    NASA Astrophysics Data System (ADS)

    Tarabrin, Sergey P.; Kaufer, Henning; Khalili, Farid Ya.; Schnabel, Roman; Hammerer, Klemens

    2013-08-01

    We analyze the dynamic optomechanical backaction in signal-recycled Michelson and Michelson-Sagnac interferometers that are operated off the dark port. We show that in this case—and in contrast to the well-studied canonical form of dynamic backaction on the dark port—optical damping in a Michelson-Sagnac interferometer acquires a nonzero value on cavity resonance, and additional stability and instability regions on either side of the resonance, revealing additional regimes of cooling and heating of micromechanical oscillators. In a free-mass Michelson interferometer for a certain region of parameters we predict a stable single-carrier optical spring (positive spring and positive damping), which can be utilized for the reduction of quantum noise in future-generation gravitational-wave detectors.

  14. Intestinal absorption and intestinal lymphatic transport of sirolimus from self-microemulsifying drug delivery systems assessed using the single-pass intestinal perfusion (SPIP) technique and a chylomicron flow blocking approach: linear correlation with oral bioavailabilities in rats.

    PubMed

    Sun, Minghui; Zhai, Xuezhen; Xue, Kewen; Hu, Lei; Yang, Xiangliang; Li, Gao; Si, Luqin

    2011-06-14

    This work aims to investigate the impact of different amount of oil or surfactant included in self-microemulsifying drug delivery systems on the intestinal lymphatic transport of sirolimus using the single-pass intestinal perfusion (SPIP) technique and a chylomicron flow blocking approach. Male Sprague-Dawley rats were pretreated intraperitoneally with 3.0mg/kg cycloheximide or saline. One hour later, single-pass intestinal perfusion experiments in jejunum and ileum and in vivo bioavailability studies were carried out to calculate the effective permeability coefficient and pharmacokinetic parameters, respectively. Drug absorption from oil-free formulation was mostly via the portal blood. In contrast, for the SMEDDS formulations containing ?25% MCT, the lymphatic transport of sirolimus was a major contributor to oral bioavailability. The formulation including more content of oil presented higher lymphatic transport of drug and further exhibited the increased oral bioavailability. Besides, distal ileum presented much more lymphatic transport of drug compared to proximal jejunum. Furthermore, even though the smaller droplet size of resultant microemulsions and more surfactant content also can positively influence the intestinal absorption of drug, their influences on the drug intestinal lymphatic transport were relatively weaker than that of more oil content. In addition, there was a high linear correlation between the AUC values and the mean of P(eff) values in jejunum and ileum. PMID:21530655

  15. A review of earth-based radar mapping of the moon

    NASA Technical Reports Server (NTRS)

    Thompson, T. W.

    1979-01-01

    Lunar radar mappings carried out in the late 1960s and 1970s have provided several valuable insights into lunar surface processes. These radar mappings used the delay-Doppler technique and needed the narrow antenna beams now available with large radio telescopes. Two-element radar interferometers have provided resolution of the delay-Doppler ambiguity at meter wavelengths and provided topographic information at centimeter wavelengths. These techniques have provided high resolution lunar radar maps at 3.8-cm, 70-cm, and 7.5-m wavelengths, a set of wavelengths which span the window available for earth-based radar mapping of the moon. These radar maps have been used along with other earth-based and Apollo orbital measurements to define surface units. The radar maps and these other data can describe physical properties such as small-scale blockiness and surface chemistry.

  16. 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.

  17. Radar TopoMapper concept for planetary exploration

    NASA Astrophysics Data System (ADS)

    Madsen, Soren N.; Lou, Yun-Ling; Hensley, Scott; Harvey, Wayne L.; McKinnon, William B.

    2004-12-01

    Topographic information is key to interpreting the geology and geophysics of planetary bodies such as the icy Galilean satellites. Traditionally elevation information has been derived from stereo-photogrammetry, but the last couple of decades have offered new techniques, including radar interferometry, photoclinometry (shape from shading) and laser altimetry. Combining synthetic aperture radar (SAR) technology with interferometry (InSAR) enables high resolution imaging with elevation information at each image point. With two appropriately spaced antennas on a spacecraft, single-pass imaging radar interferometry can provide wide swath topographic data, independent of solar illumination, as was recently demonstrated on Earth by the Shuttle Topographic Radar Mission (SRTM; www.jpl.nasa.gov/srtm). We will present the science requirements, measurement principle, a straw-man"s design, and the predicted performance of a "compact SRTM" which could be flown on NASA missions such as the proposed Jupiter Icy Moons Orbiter (JIMO). In this paper we discuss challenges, including the calibration strategy and critical technology elements such as the high power RF-amplifier. We expect that the performance, both in terms of elevation accuracy and mapping rate would suffice to 1) determine topography on local and regional scales; 2) search for active geological change on the time scale of JIMO"s orbit around, e.g., Europa (30-60 days); and 3) determine the global tidal amplitude at Europa, Callisto, and Ganymede, which would constitute direct proof of the existence of oceans in all three icy moons.

  18. 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.

  19. A Martin-Puplett cartridge FIR interferometer

    NASA Astrophysics Data System (ADS)

    Smith, Roger J.; Penniman, Edwin E.; Jarboe, Thomas R.

    2004-10-01

    A compact prealigned Martin-Puplett interferometer (MPI) cartridge for plasma interferometry is described. The MPI cartridge groups all components of a MP interferometer, with the exception of the end mirror for the scene beam, on a stand-alone rigid platform. The interferometer system is completed by positioning a cartridge anywhere along and coaxial with the scene beam, considerably reducing the amount of effort in alignment over a discrete component layout. This allows the interferometer to be expanded to any number of interferometry chords consistent with optical access, limited only by the laser power. The cartridge interferometer has been successfully incorporated as a second chord on the Helicity Injected Torus II (HIT-II) far infrared interferometer system and a comparison with the discrete component system is presented. Given the utility and compactness of the cartridge, a possible design for a five-chord interferometer arrangement on the HIT-II device is described.

  20. 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.

  1. Using dynamic interferometric synthetic aperature radar (InSAR) to image fast-moving surface waves

    DOEpatents

    Vincent, Paul

    2005-06-28

    A new differential technique and system for imaging dynamic (fast moving) surface waves using Dynamic Interferometric Synthetic Aperture Radar (InSAR) is introduced. This differential technique and system can sample the fast-moving surface displacement waves from a plurality of moving platform positions in either a repeat-pass single-antenna or a single-pass mode having a single-antenna dual-phase receiver or having dual physically separate antennas, and reconstruct a plurality of phase differentials from a plurality of platform positions to produce a series of desired interferometric images of the fast moving waves.

  2. Divertor interferometer diagnostic for ITER

    SciTech Connect

    Brower, D. L.; Deng, B. H.; Ding, W. X.

    2006-10-15

    In the harsh environment of the divertor region in ITER, plasmas spanning a huge density range from 10{sup 19} to 10{sup 22} m{sup -3} are anticipated making measurement of the electron density particularly challenging. For any reasonable wavelength choice, the total phase measured by a conventional two-color interferometer system is always >>2{pi} and therefore subject to fringe counting errors. This problem can be remedied by adding a polarimeter capability whereby the Cotton-Mouton effect is measured or by employing differential interferometry. Using either approach, the total phase is always <<2{pi}. The conceptual design of an interferometer system along with possible wavelength choices will be explored.

  3. Stellar Interferometer Technology Experiment (SITE)

    NASA Technical Reports Server (NTRS)

    Crawley, Edward F.; Miller, David; Laskin, Robert; Shao, Michael

    1995-01-01

    The MIT Space Engineering Research Center and the Jet Propulsion Laboratory stand ready to advance science sensor technology for discrete-aperture astronomical instruments such as space-based optical interferometers. The objective of the Stellar Interferometer Technology Experiment (SITE) is to demonstrate system-level functionality of a space-based stellar interferometer through the use of enabling and enhancing Controlled-Structures Technologies (CST). SITE mounts to the Mission Peculiar Experiment Support System inside the Shuttle payload bay. Starlight, entering through two apertures, is steered to a combining plate where it is interferred. Interference requires 27 nanometer pathlength (phasing) and 0.29 archsecond wavefront-tilt (pointing) control. The resulting 15 milli-archsecond angular resolution exceeds that of current earth-orbiting telescopes while maintaining low cost by exploiting active optics and structural control technologies. With these technologies, unforeseen and time-varying disturbances can be rejected while relaxing reliance on ground alignment and calibration. SITE will reduce the risk and cost of advanced optical space systems by validating critical technologies in their operational environment. Moreover, these technologies are directly applicable to commercially driven applications such as precision matching, optical scanning, and vibration and noise control systems for the aerospace, medical, and automotive sectors. The SITE team consists of experienced university, government, and industry researchers, scientists, and engineers with extensive expertise in optical interferometry, nano-precision opto-mechanical control and spaceflight experimentation. The experience exists and the technology is mature. SITE will validate these technologies on a functioning interferometer science sensor in order to confirm definitely their readiness to be baselined for future science missions.

  4. 10-micron heterodyne stellar interferometer

    NASA Technical Reports Server (NTRS)

    Johnson, M. A.; Betz, A. L.; Townes, C. H.

    1974-01-01

    A spatial interferometer for 10-micron wavelength which uses two independent telescopes separated by 5.5 m, heterodyne detection of the infrared radiation, and path equalization by a variable-length RF cable, has given interference fringes from radiation of the planet Mercury. Continuous fringe observations during 4000 sec indicate remarkable stability in the optical-path difference through the atmosphere and the two telescopes, fluctuations between 20-sec averages being about 1/6 of the 10-micron wavelength.

  5. Polarized-interferometer feasibility study

    NASA Technical Reports Server (NTRS)

    Raab, F. H.

    1983-01-01

    The feasibility of using a polarized-interferometer system as a rendezvous and docking sensor for two cooperating spacecraft was studied. The polarized interferometer is a radio frequency system for long range, real time determination of relative position and attitude. Range is determined by round trip signal timing. Direction is determined by radio interferometry. Relative roll is determined from signal polarization. Each spacecraft is equipped with a transponder and an antenna array. The antenna arrays consist of four crossed dipoles that can transmit or receive either circularly or linearly polarized signals. The active spacecraft is equipped with a sophisticated transponder and makes all measurements. The transponder on the passive spacecraft is a relatively simple repeater. An initialization algorithm is developed to estimate position and attitude without any a priori information. A tracking algorithm based upon minimum variance linear estimators is also developed. Techniques to simplify the transponder on the passive spacecraft are investigated and a suitable configuration is determined. A multiple carrier CW signal format is selected. The dependence of range accuracy and ambiguity resolution error probability are derived and used to design a candidate system. The validity of the design and the feasibility of the polarized interferometer concept are verified by simulation.

  6. Fifty years of radar

    NASA Astrophysics Data System (ADS)

    Skolnik, M. I.

    1985-02-01

    A development history of radar technology is presented, with attention to the driving of radar system design advances by the emergence of such weapon systems as long range aircraft and cruise missiles in World War II and the range of current applications for state-of-the-art radar techniques. The applications noted encompass over-the-horizon backscatter radars for aircraft detection at 500-1800 nmi ranges, ultralow sidelobe antenna military radars, a long range, frequency scanning three-dimensional S-band radar, a shipborne phased array radar for the collection of exoatmospheric and endoatmospheric data on ballistic missile reentry vehicles, multimission/multimode X-band fighter aircraft radars, and phased array air defense radars.

  7. Keck Interferometer Science: Present and Future

    NASA Technical Reports Server (NTRS)

    Akeson, Rachel L.

    2004-01-01

    The Keck Interferometer is a NASA funded project developed by the Jet Propulsion Laboratory, the William M. Keck Observatory and the Michelson Science Center at the California Institute of Technology. A technical description of the interferometer is given elsewhere in this volume. This paper will discuss the science topics and goals of the Keck Interferometer project, including a brief description of the Key Science projects, the science projects executed to date and the current availability of the interferometer for new projects. The Keck Interferometer Project consists of the Keck-Keck Interferometer, which combines the two Keck lo-meter telescopes on an 85-meter baseline, and the Outrigger Telescopes Project, a proposal to add four to six 1.8-meter telescopes that would work in conjunction with the two Kecks.

  8. Nonlocal polarization interferometer for entanglement detection

    SciTech Connect

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

    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.

  9. Single Pass Electron Cooling Simulations for MEIC

    SciTech Connect

    Bell, G. I.; Pogorelov, I. V.; Schwartz, B. T.; Zhang, Yuhong; Zhang, He

    2013-12-01

    Cooling of medium energy protons is critical for the proposed Jefferson Lab Medium Energy Ion Collider (MEIC). We present simulations of electron cooling of protons up to 60 GeV. In the beam frame in which the proton and electrons are co-propagating, their motion is non-relativistic. We use a binary collision model which treats the cooling process as the sum of a large number of two-body collisions which are calculated exactly. This model can treat even very close collisions between an electron and ion with high accuracy. We also calculate dynamical friction using a delta-f PIC model. The code VSim (formerly Vorpal) is used to perform the simulations. We compare the friction rates with that obtained by a 3D integral over electron velocities which is used by BETACOOL.

  10. A new x-ray interferometer

    NASA Astrophysics Data System (ADS)

    Kitamoto, S.; Murakami, H.; Takei, D.; Sakata, K.; Yoshida, Y.

    2011-09-01

    We report a study of a new X-ray interferometer with a beam splitter for future observation of celestial objects. A possible configuration of an interferometer is proposed. By using a beam splitter, the length of the interferometer becomes short and without a formation flight of satellites a reasonable X-ray interferometric observation can be possible. An observation of early type stars is discussed. A laboratory experiment for performance verification is also discussed.

  11. Perimitrax: the next generation in guided radar perimeter security technology

    NASA Astrophysics Data System (ADS)

    Maki, Melvin C.; Hill, Charles R.

    1997-01-01

    The first application of 'leaky' or 'ported' coaxial cables to radar system for covert detection of human intruders for outdoor perimeter security was in the early 1970's. Early systems were relatively rudimentary using large central processors and difficult to manufacture sensing cables. However, since that time these systems have evolved in both design and performance and been proven to have both high detection performance and low false and nuisance response in such diverse, all-weather perimeter applications as military bases, corrections, and industrial sites. This paper introduces the latest generation of guided radar security technology now being fielded. This generation features more flexible and modular 'plug and play' electronics, matched to both large and small installations from the sensor zone end, up to the control and display. Advanced signal processing is now included which is tuned to discriminate the unique features of the intruder from those of the environment. Such processing capitalize on the ability to look at and classify features of larger perimeters. New 'TR' technology sensor cables have ben developed which are manufactured in a single pass approach to provide more uniformity of sensor performance. These sensor include both a siamese design for single slot burial, and also a small diameter dual cable for wider zone requirements. This paper will outline the major elements of guided radar sensors and overview the new components and architecture of this latest generation. It will discuss the results of early operational performance testing, and the new benefits for diverse applications from government, to corrections and airports.

  12. Ordinary SQUID interferometers and superfluid helium matter wave interferometers: The role of quantum fluctuations

    SciTech Connect

    Golovashkin, A. I.; Zherikhina, L. N. Tskhovrebov, A. M.; Izmailov, G. N.; Ozolin, V. V.

    2010-08-15

    When comparing the operation of a superfluid helium matter wave quantum interferometer (He SQUID) with that of an ordinary direct-current quantum interferometer (dc SQUID), we estimate their resolution limitation that correspond to quantum fluctuations. An alternative mode of operation of the interferometer as a unified macroquantum system is considered.

  13. Spectropolarimetric analysis of differential interferometer

    NASA Astrophysics Data System (ADS)

    Gut, Kazimierz

    2014-08-01

    The paper presents the principle of the operation of a spectropolarimetric interferometer. In the planar waveguide orthogonal modes of type TE and TM can be excited for the entire visible light. During the propagation the difference of the phases between the modes is determined, which is the function of the length of the path of propagation, the difference of the effective refractive index (NTM-NTE) and the wavelength. At the output of this system the spectral distribution of intensity is recorded, the shape of which depends on the value of the refractive index of the cover of the waveguides.

  14. Quantum noise in optical interferometers

    SciTech Connect

    Voronov, Volodymyr G.; Weyrauch, Michael

    2010-05-15

    We study the photon counting noise in optical interferometers used for gravitational wave detection. In order to reduce quantum noise, a squeezed vacuum is injected into the usually unused input port. It is investigated under which conditions the gravitational wave signal may be amplified without increasing counting noise concurrently. Such a possibility was suggested as a consequence of the entanglement of the two output ports of a beam splitter. We find that amplification without concurrent increase of noise is not possible for reasonable squeezing parameters. Photon distributions for various beam splitter angles and squeezing parameters are calculated.

  15. Doppler radar results

    NASA Technical Reports Server (NTRS)

    Bracalente, Emedio M.

    1992-01-01

    The topics are covered in viewgraph form and include the following: (1) a summary of radar flight data collected; (2) a video of combined aft cockpit, nose camera, and radar hazard displays; (3) a comparison of airborne radar F-factor measurements with in situ and Terminal Doppler Weather Radar (TDWR) F-factors for some sample events; and (4) a summary of wind shear detection performance.

  16. 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.

  17. Interferometer for Space Station Windows

    NASA Technical Reports Server (NTRS)

    Hall, Gregory

    2003-01-01

    Inspection of space station windows for micrometeorite damage would be a difficult task insitu using current inspection techniques. Commercially available optical profilometers and inspection systems are relatively large, about the size of a desktop computer tower, and require a stable platform to inspect the test object. Also, many devices currently available are designed for a laboratory or controlled environments requiring external computer control. This paper presents an approach using a highly developed optical interferometer to inspect the windows from inside the space station itself using a self- contained hand held device. The interferometer would be capable as a minimum of detecting damage as small as one ten thousands of an inch in diameter and depth while interrogating a relatively large area. The current developmental state of this device is still in the proof of concept stage. The background section of this paper will discuss the current state of the art of profilometers as well as the desired configuration of the self-contained, hand held device. Then, a discussion of the developments and findings that will allow the configuration change with suggested approaches appearing in the proof of concept section.

  18. Note: Periodic error measurement in heterodyne interferometers using a subpicometer accuracy Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Zhu, Minhao; Wei, Haoyun; Wu, Xuejian; Li, Yan

    2014-08-01

    Periodic error is the major problem that limits the accuracy of heterodyne interferometry. A traceable system for periodic error measurement is developed based on a nonlinearity free Fabry-Perot (F-P) interferometer. The displacement accuracy of the F-P interferometer is 0.49 pm at 80 ms averaging time, with the measurement results referenced to an optical frequency comb. Experimental comparison between the F-P interferometer and a commercial heterodyne interferometer is carried out and it shows that the first harmonic periodic error dominates in the commercial heterodyne interferometer with an error amplitude of 4.64 nm.

  19. Liquid-Crystal Point-Diffraction Interferometer

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R.

    1996-01-01

    Liquid-crystal point-diffraction interferometer (LCPDI) invented to combine flexible control of liquid-crystal phase-shifts with robustness of point-diffraction interferometers. Produces interferograms indicative of shapes of wavefronts of laser beams having passed through or reflected from objects of interest. Interferograms combined in computers to produce phase maps describing wavefronts.

  20. Dual-prism interferometer for collimation testing

    SciTech Connect

    Hii, King Ung; Kwek, Kuan Hiang

    2009-01-10

    An air-wedge lateral-shear interferometer using two prisms is presented. With a variable shear, the interferometer is suitable for testing collimation of a wide range of beam sizes down to a few millimeters in diameter. No antireflection coatings are necessary. Collimation for a light source with short coherent length is also demonstrated.

  1. 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.

  2. Development of a radiation pressure noise interferometer

    NASA Astrophysics Data System (ADS)

    Okutomi, Akira; Yamamoto, K.; Miyoki, S.; Ohashi, M.; Kuroda, K.

    2006-03-01

    We are developing a small-scale interferometer in order to observe radiation pressure noise. This radiation pressure noise interferometer is composed of two cavities whose mirror mass is less than 1g. In this system, radiation pressure noise is dominant around at a few hundred Hz. The design and the current status of our prototype system are described.

  3. Orientational atom interferometers sensitive to gravitational waves

    SciTech Connect

    Lorek, Dennis; Laemmerzahl, Claus; Wicht, Andreas

    2010-02-15

    We present an atom interferometer that differs from common atom interferometers as it is not based on the spatial splitting of electronic wave functions, but on orienting atoms in space. As an example we present how an orientational atom interferometer based on highly charged hydrogen-like atoms is affected by gravitational waves. We show that a monochromatic gravitational wave will cause a frequency shift that scales with the binding energy of the system rather than with its physical dimension. For a gravitational wave amplitude of h=10{sup -23} the frequency shift is of the order of 110 {mu}Hz for an atom interferometer based on a 91-fold charged uranium ion. A frequency difference of this size can be resolved by current atom interferometers in 1 s.

  4. 102?k large area atom interferometers.

    PubMed

    Chiow, Sheng-wey; Kovachy, Tim; Chien, Hui-Chun; Kasevich, Mark A

    2011-09-23

    We demonstrate atom interferometers utilizing a novel beam splitter based on sequential multiphoton Bragg diffractions. With this sequential Bragg large momentum transfer (SB-LMT) beam splitter, we achieve high contrast atom interferometers with momentum splittings of up to 102 photon recoil momenta (102?k). To our knowledge, this is the highest momentum splitting achieved in any atom interferometer, advancing the state-of-the-art by an order of magnitude. We also demonstrate strong noise correlation between two simultaneous SB-LMT interferometers, which alleviates the need for ultralow noise lasers and ultrastable inertial environments in some future applications. Our method is intrinsically scalable and can be used to dramatically increase the sensitivity of atom interferometers in a wide range of applications, including inertial sensing, measuring the fine structure constant, and detecting gravitational waves. PMID:22026831

  5. Planetary Radar Astronomy

    NASA Astrophysics Data System (ADS)

    Black, Gregory J.

    2002-12-01

    Radar is a powerful tool for studying the Solar System, with its reach limited in theory only by the transmitter power available. It has been used to observe targets ranging in size from the rings of Saturn down to house-sized asteroids. An observer has control of the illumination source, so a radar experiment provides information not available from passive observing methods. On centimeter to meter scales it is a sensitive probe of surface characteristics such as dielectric constant and roughness, and on larger scales can map topography and determine shapes of irregular objects at resolutions finer than other ground-based methods. This lecture will cover the basic techniques of planetary radar astronomy, give an overview of the scientific questions that can be addressed, and survey some recent results. Key points of the lecture will be: what can be learned from radar experiments; types of radar experiments; observable quantities; the radar equation; and an outline of current radar systems.

  6. Planetary radar astronomy

    NASA Technical Reports Server (NTRS)

    Ostro, Steven J.

    1987-01-01

    The scientific aims, theoretical principles, techniques and instrumentation, and future potential of radar observations of solar-system objects are discussed in a general overview. Topics examined include the history of radar technology, echo detectability, the Arecibo and Goldstone radar observatories, echo time delay and Doppler shift, radar waveforms, albedo and polarization ratio, measurement of dynamical properties, and the dispersion of echo power. Consideration is given to angular scattering laws; the radar signatures of the moon and inner planets, Mars, and asteroids; topographic relief; delay-Doppler radar maps and their physical interpretation; and radar observations of the icy Galilean satellites of Jupiter, comets, and the rings of Saturn. Diagrams, drawings, photographs, and sample maps and images are provided.

  7. Planetary radar astronomy

    NASA Astrophysics Data System (ADS)

    Ostro, Steven J.

    The scientific aims, theoretical principles, techniques and instrumentation, and future potential of radar observations of solar-system objects are discussed in a general overview. Topics examined include the history of radar technology, echo detectability, the Arecibo and Goldstone radar observatories, echo time delay and Doppler shift, radar waveforms, albedo and polarization ratio, measurement of dynamical properties, and the dispersion of echo power. Consideration is given to angular scattering laws; the radar signatures of the moon and inner planets, Mars, and asteroids; topographic relief; delay-Doppler radar maps and their physical interpretation; and radar observations of the icy Galilean satellites of Jupiter, comets, and the rings of Saturn. Diagrams, drawings, photographs, and sample maps and images are provided.

  8. 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.

  9. Beam shuttering interferometer and method

    DOEpatents

    Deason, V.A.; Lassahn, G.D.

    1993-07-27

    A method and apparatus resulting in the simplification of phase shifting interferometry by eliminating the requirement to know the phase shift between interferograms or to keep the phase shift between interferograms constant. The present invention provides a simple, inexpensive means to shutter each independent beam of the interferometer in order to facilitate the data acquisition requirements for optical interferometry and phase shifting interferometry. By eliminating the requirement to know the phase shift between interferograms or to keep the phase shift constant, a simple, economical means and apparatus for performing the technique of phase shifting interferometry is provide which, by thermally expanding a fiber optical cable changes the optical path distance of one incident beam relative to another.

  10. Navy precision optical interferometer database

    NASA Astrophysics Data System (ADS)

    Ryan, K. K.; Jorgensen, A. M.; Hall, T.; Armstrong, J. T.; Hutter, D.; Mozurkewich, D.

    2012-07-01

    The Navy Precision Optical Interferometer (NPOI) has now been recording astronomical observations for the better part of two decades. During that time period hundreds of thousands of observations have been obtained, with a total data volume of multiple terabytes. Additionally, in the next few years the data rate from the NPOI is expected to increase significantly. To make it easier for NPOI users to search the NPOI observations and to make it easier for them to obtain data, we have constructed a easily accessible and searchable database of observations. The database is based on a MySQL server and uses standard query language (SQL). In this paper we will describe the database table layout and show examples of possible database queries.

  11. 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.

  12. Beam shuttering interferometer and method

    DOEpatents

    Deason, Vance A. (Idaho Falls, ID); Lassahn, Gordon D. (Idaho Falls, ID)

    1993-01-01

    A method and apparatus resulting in the simplification of phase shifting interferometry by eliminating the requirement to know the phase shift between interferograms or to keep the phase shift between interferograms constant. The present invention provides a simple, inexpensive means to shutter each independent beam of the interferometer in order to facilitate the data acquisition requirements for optical interferometry and phase shifting interferometry. By eliminating the requirement to know the phase shift between interferograms or to keep the phase shift constant, a simple, economical means and apparatus for performing the technique of phase shifting interferometry is provide which, by thermally expanding a fiber optical cable changes the optical path distance of one incident beam relative to another.

  13. Michelson interferometer for laser wavelength

    NASA Astrophysics Data System (ADS)

    Wang, Liqiang; Ren, Wenjie

    2005-11-01

    A wavemeter based on Michelson interferometer accurately measure static wavelength of a tunable laser. Its operation principle is formulated in details. Double longitudinal-mode He-Ne laser with frequency stabilization is used as the reference optical source of the wavemeter. Voice-coil motor using PID means can realize to move in uniform motion. Phase-locked loop circuit including NE564 and 74LS193 is used to enhance resolution of the wavemeter. Data processing is carried out by the counter unit including two 8254 programmable timer, a MCU, a LCD. The test shows that its measurement accuracy is 1×10 -6 and is higher than those of other wavemeters such as Fizeau interference and Fabry-Perot wavemeter.

  14. Radar observations of ion cyclotron waves associated with two barium shaped-charge releases

    NASA Astrophysics Data System (ADS)

    Providakes, Jason; Swartz, Wesley E.; Kelley, Michael C.; Djuth, Frank T.; Noble, Steve

    1990-12-01

    Plasma waves associated with two shaped-charge barium releases from Wallops Island (Virginia) on May 13, 1986 were investigated using a 50 MHz Doppler radar interferometer and a 138-MHz Doppler radar operated from Kennedy Space Center. During the first barium release, measurements showed the existence of short-lived coherent 3-m and 1-m waves centered near 30 Hz. The coherent 30-Hz radar echoes were very similar to some naturally occurring auroral radar echoes that are believed to be generated by resistive current-driven electrostatic ion cyclotron (EIC) waves. The 30-Hz waves seen by the two radars far above the release are interpreted as strong EIC waves generated by intense field-aligned currents associated with the barium stream acting like an MHD generator coupled to the ionosphere.

  15. 2. VIEW SOUTHWEST, prime search radar tower, height finder radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. VIEW SOUTHWEST, prime search radar tower, height finder radar towards, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  16. Interlaboratory study of the reproducibility of the single-pass flow-through test method : measuring the dissolution rate of LRM glass at 70 {sup {degree}}C and pH 10.

    SciTech Connect

    Ebert, W. L.; Chemical Engineering

    2006-02-28

    An international interlaboratory study (ILS) was conducted to evaluate the precision with which single-pass flow-through (SPFT) tests can be conducted by following a method to be standardized by the American Society for Testing and Materials - International. Tests for the ILS were conducted with the low-activity reference material (LRM) glass developed previously for use as a glass test standard. Tests were conducted at 70 {+-} 2 C using a LiCl/LiOH solution as the leachant to impose an initial pH of about 10 (at 70 C). Participants were provided with LRM glass that had been crushed and sieved to isolate the -100 +200 mesh size fraction, and then washed to remove fines. Participants were asked to conduct a series of tests using different solution flow rate-to-sample mass ratios to generate a range of steady-state Si concentrations. The glass dissolution rate under each test condition was calculated using the steady-state Si concentration and solution flow rate that were measured in the test. The glass surface area was estimated from the mass of glass used in the test and the Si content of LRM glass was known. A linear relationship between the rate and the steady-state Si concentration (at Si concentrations less than 10 mg/L) was used to estimate the forward dissolution rate, which is the rate in the absence of dissolved Si. Participants were asked to sample the effluent solution at least five times after reaction times of between 3 and 14 days to measure the Si concentration and flow rate, and to verify that steady-state was achieved. Results were provided by seven participants and the data sets provided by five participants were sufficient to determine the forward rates independently.

  17. Magdalena Ridge Observatory Interferometer: status update

    NASA Astrophysics Data System (ADS)

    Creech-Eakman, M. J.; Bakker, E. J.; Buscher, D. F.; Coleman, T. A.; Haniff, C. A.; Jurgenson, C. A.; Klinglesmith, D. A., III; Parameswariah, C. B.; Romero, V. D.; Shtromberg, A. V.; Young, J. S.

    2006-06-01

    The Magdalena Ridge Observatory Interferometer (MROI) is a ten element optical and near-infrared imaging interferometer being built in the Magdalena mountains west of Socorro, NM at an altitude of 3230 m. The interferometer is being designed and built by a collaboration which includes the New Mexico Institute of Mining and Technology (NMT) as the prime contractor and center for the technical team, and the University of Cambridge, Physics Department at the Cavendish Laboratory, which participates in the design and executes work packages under contract with NMT. This manuscript serves as a status update on MROI, and will present progress and milestones toward the observatory's first fringes in 2008.

  18. The Millimeter-Wave Bolometric Interferometer

    NASA Technical Reports Server (NTRS)

    Ali, S.; Ade, P. A. R.; Bock, J. J.; Novak, G.; Piccirillo, L.; Timbie, P.; Tucker, G. S.

    2004-01-01

    The Millimeter-wave Bolometric Interferometer (MBI) is a proposed ground-based instrument designed for a wide range of cosmological and astrophysical observations including studies of the polarization of the cosmic microwave background (CMB). MBI combines the advantages of two well-developed technologies - interferometers and bolometric detectors. Interferometers have many advantages over .filled-aperture telescopes and are particularly suitable for high resolution imaging. Cooled bolometers are the highest sensitivity detectors at millimeter and sub-millimeter wavelengths. The combination of these two technologies results in an instrument with both high sensitivity and high angular resolution.

  19. Dynamic models of Fabry-Perot interferometers.

    PubMed

    Redding, David; Regehr, Martin; Sievers, Lisa

    2002-05-20

    Long-baseline, high-finesse Fabry-Perot interferometers can be used to make distance measurements that are precise enough to detect gravity waves. This level of sensitivity is achieved in part when the interferometer mirrors are isolated dynamically, with pendulum mounts and high-bandwidth cavity length control servos to reduce the effects of seismic noise. We present dynamical models of the cavity fields and signals of Fabry-Perot interferometers for use in the design and evaluation of length control systems for gravity-wave detectors. Models are described and compared with experimental data. PMID:12027177

  20. Comparative Sensitivities of Gravitational Wave Detectors Based on Atom Interferometers and Light Interferometers

    NASA Technical Reports Server (NTRS)

    Baker, John G.; Thorpe, J. I.

    2012-01-01

    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. Whether this potential advantage outweighs the additional complexity associated with including atom interferometers will require further study.

  1. 3. VIEW NORTHWEST, height finder radar towers, and radar tower ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. VIEW NORTHWEST, height finder radar towers, and radar tower (unknown function) - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  2. 30. Perimeter acquisition radar building room #318, showing radar control. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. Perimeter acquisition radar building room #318, showing radar control. Console and line printers - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  3. Planetary radar studies

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    A catalog of lunar and radar anomalies was generated to provide a base for comparison with Venusian radar signatures. The relationships between lunar radar anomalies and regolith processes were investigated, and a consortium was formed to compare lunar and Venusian radar images of craters. Time was scheduled at the Arecibo Observatory to use the 430 MHz radar to obtain high resolution radar maps of six areas of the lunar suface. Data from 1978 observations of Mare Serenitas and Plato are being analyzed on a PDP 11/70 computer to construct the computer program library necessary for the eventual reduction of the May 1981 and subsequent data acquisitions. Papers accepted for publication are presented.

  4. Laser radar in robotics

    SciTech Connect

    Carmer, D.C.; Peterson, L.M.

    1996-02-01

    In this paper the authors describe the basic operating principles of laser radar sensors and the typical algorithms used to process laser radar imagery for robotic applications. The authors review 12 laser radar sensors to illustrate the variety of systems that have been applied to robotic applications wherein information extracted from the laser radar data is used to automatically control a mechanism or process. Next, they describe selected robotic applications in seven areas: autonomous vehicle navigation, walking machine foot placement, automated service vehicles, manufacturing and inspection, automotive, military, and agriculture. They conclude with a discussion of the status of laser radar technology and suggest trends seen in the application of laser radar sensors to robotics. Many new applications are expected as the maturity level progresses and system costs are reduced.

  5. 1999 IEEE radar conference

    SciTech Connect

    1999-07-01

    This conference addresses the stringent radar technology demands facing the next century: target detection, tracking and identification; changing target environment; increased clutter mitigation techniques; air traffic control; transportation; drug smuggling; remote sensing, and other consumer oriented applications. A timely discussion covers how to minimize costs for these emerging areas. Advanced radar technology theory and applications are also presented. Topics covered include: signal processing; space time adaptive processing/antennas; surveillance technology; radar systems; dual use; and phenomenology.

  6. Bistatic-radar investigation

    NASA Technical Reports Server (NTRS)

    Howard, H. T.; Tyler, G. L.

    1972-01-01

    A bistatic-radar study during the Apollo 15 flight is reviewed, with the orbiting command module as one terminal. Bistatic-radar slopes are compared to geological maps of Copernicus and Riphaeus mountain regions and Kepler region. Basic theory is discussed, including the radar echoes composed of the sum of the reflections from the moon area that is mutually visible from the spacecraft and earth. A signal receiving system and data processing system are outlined schematically.

  7. 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

  8. 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.

  9. Planetary radar astronomy

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1983-03-01

    The present investigation is concerned with planetary radar research reported during the time from 1979 to 1982. A brief synopsis of radar definitions and technical terminology is also provided. In connection with the proximity of the moon to earth, lunar radar studies have been performed over a wider range of wavelengths than radar investigations of other planetary targets. The most recent study of lunar quasispecular scattering is due to Simpson and Tyler (1982). The latest efforts to interpret the lunar radar maps focus on maria-highlands regolith differences and models of crater ejecta evolution. The highly successful Pioneer Venus Radar Mapper experiment has provided a first look at Venus' global distributions of topography, lambda 17-cm radar reflectivity, and rms surface slopes. Attention is given to recent comparisons of Viking Orbiter images of Mars to groundbased radar altimetry of the planet, the icy Galilean satellites, radar observations of asteroids and comets, and lambda 4-cm and lambda 13-cm observations of Saturn's rings.

  10. 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.

  11. 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.

  12. Single and double superimposing interferometer systems

    DOEpatents

    Erskine, David J. (Oakland, CA)

    2000-01-01

    Interferometers which can imprint a coherent delay on a broadband uncollimated beam are described. The delay value can be independent of incident ray angle, allowing interferometry using uncollimated beams from common extended sources such as lamps and fiber bundles, and facilitating Fourier Transform spectroscopy of wide angle sources. Pairs of such interferometers matched in delay and dispersion can measure velocity and communicate using ordinary lamps, wide diameter optical fibers and arbitrary non-imaging paths, and not requiring a laser.

  13. Nonlinear Michelson interferometer for improved quantum metrology

    NASA Astrophysics Data System (ADS)

    Luis, Alfredo; Rivas, Ángel

    2015-08-01

    We examine quantum detection via a Michelson interferometer embedded in a gas with Kerr nonlinearity. This nonlinear 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 processes. 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.

  14. Digital Array Scanned Interferometer: Sensors And Results

    NASA Technical Reports Server (NTRS)

    Smith, William Hyaden; Hammer, Philip D.; Peterson, David L. (Technical Monitor)

    1995-01-01

    Digital Array Scanned Interferometers (DASI), blend characteristics of a grating spectrometer and a two-beam interferometer for acquisition of hyperspectra. DASIs possess field widened capabilities that permit very high throughput. Aspects of DASI design, hyperspectra and data processing methods are presented. In particular, we provide data showing the important result that photon noise limited hyperspectra are achievable for DASI data acquired with a variety of FPAs.

  15. 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.

  16. Achromatic self-referencing interferometer

    DOEpatents

    Feldman, Mark (Pleasanton, CA)

    1994-01-01

    A self-referencing Mach-Zehnder interferometer 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 ("first" 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.

  17. Subsurface "radar" camera

    NASA Technical Reports Server (NTRS)

    Jain, A.

    1977-01-01

    Long-wave length multiple-frequency radar is used for imaging and determining depth of subsurface stratified layers. Very-low frequency radar signals pinpoint below-ground strata via direct imagery techniques. Variation of frequency and scanning angle adjusts image depth and width.

  18. Radar illusion via metamaterials

    NASA Astrophysics Data System (ADS)

    Jiang, Wei Xiang; Cui, Tie Jun

    2011-02-01

    An optical illusion is an image of a real target perceived by the eye that is deceptive or misleading due to a physiological illusion or a specific visual trick. The recently developed metamaterials provide efficient approaches to generate a perfect optical illusion. However, all existing research on metamaterial illusions has been limited to theory and numerical simulations. Here, we propose the concept of a radar illusion, which can make the electromagnetic (EM) image of a target gathered by radar look like a different target, and we realize a radar illusion device experimentally to change the radar image of a metallic target into a dielectric target with predesigned size and material parameters. It is well known that the radar signatures of metallic and dielectric objects are significantly different. However, when a metallic target is enclosed by the proposed illusion device, its EM scattering characteristics will be identical to that of a predesigned dielectric object under the illumination of radar waves. Such an illusion device will confuse the radar, and hence the real EM properties of the metallic target cannot be perceived. We designed and fabricated the radar illusion device using artificial metamaterials in the microwave frequency, and good illusion performances are observed in the experimental results.

  19. 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.

  20. 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.

  1. The Cloud Radar System

    NASA Technical Reports Server (NTRS)

    Racette, Paul; Heymsfield, Gerald; Li, Lihua; Tian, Lin; Zenker, Ed

    2003-01-01

    Improvement in our understanding of the radiative impact of clouds on the climate system requires a comprehensive view of clouds including their physical dimensions, dynamical generation processes, and detailed microphysical properties. To this end, millimeter vave radar is a powerful tool by which clouds can be remotely sensed. The NASA Goddard Space Flight Center has developed the Cloud Radar System (CRS). CRS is a highly sensitive 94 GHz (W-band) pulsed-Doppler polarimetric radar that is designed to fly on board the NASA high-altitude ER-2 aircraft. The instrument is currently the only millimeter wave radar capable of cloud and precipitation measurements from above most all clouds. Because it operates from high-altitude, the CRS provides a unique measurement perspective for cirrus cloud studies. The CRS emulates a satellite view of clouds and precipitation systems thus providing valuable measurements for the implementation and algorithm validation for the upcoming NASA CloudSat mission that is designed to measure ice cloud distributions on the global scale using a spaceborne 94 GHz radar. This paper describes the CRS instrument and preliminary data from the recent Cirrus Regional Study of Tropical Anvils and Cirrus Layers - Florida Area Cirrus Experiment (CRYSTAL-FACE). The radar design is discussed. Characteristics of the radar are given. A block diagram illustrating functional components of the radar is shown. The performance of the CRS during the CRYSTAL-FACE campaign is discussed.

  2. Equatorial MU Radar project

    NASA Astrophysics Data System (ADS)

    Yamamoto, Mamoru; Hashiguchi, H.; Tsuda, Toshitaka; Yamamoto, Masayuki

    Research Institute for Sustainable Humanosphere, Kyoto University (RISH) has been studying the atmosphere by using radars. The first big facility was the MU (Middle and Upper atmosphere) radar installed in Shiga, Japan in 1984. This is one of the most powerful and multi-functional radar, and is successful of revealing importance of atmospheric waves for the dynamical vertical coupling processes. The next big radar was the Equatorial Atmosphere Radar (EAR) installed at Kototabang, West Sumatra, Indonesia in 2001. The EAR was operated under close collaboration with LAPAN (Indonesia National Institute for Aeronautics and Space), and conducted the long-term continuous observations of the equatorial atmosphere/ionosphere for more than 10 years. The MU radar and the EAR are both utilized for inter-university and international collaborative research program for long time. National Institute for Polar Research (NIPR) joined EISCAT Scientific Association together with Nagoya University, and developed the PANSY radar at Syowa base in Antarctica as a joint project with University of Tokyo. These are the efforts of radar study of the atmosphere/ionosphere in the polar region. Now we can find that Japan holds a global network of big atmospheric/ionospheric radars. The EAR has the limitation of lower sensitivity compared with the other big radars shown above. RISH now proposes a plan of Equatorial MU Radar (EMU) that is to establish the MU-radar class radar next to the EAR. The EMU will have an active phased array antenna with the 163m diameter and 1055 cross-element Yagis. Total output power of the EMU will be more than 500kW. The EMU can detect turbulent echoes from the mesosphere (60-80km). In the ionosphere incoherent-scatter observations of plasma density, drift, and temperature would be possible. Multi-channel receivers will realize radar-imaging observations. The EMU is one of the key facilities in the project "Study of coupling processes in the solar-terrestrial system" for Master Plan 2014 of the Science Council of Japan (SCJ). We show the EMU project and its science in the presentation.

  3. Cassini Titan Radar Mapper

    NASA Technical Reports Server (NTRS)

    Elachi, Charles; Im, Eastwood; Roth, Ladislav E.; Werner, Charles L.

    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. The requirements that lay behind the design are briefly discussed, and the configuration and capability of the instrument are described. The present limited knowledge of Titan's surface and the measurement requirements imposed on the radar instrument are addressed. Also discussed are the Cassini mission and the projected orbits, which imposed another set of design constraints that led to the multitude of modes and to an unconventional antenna configuration. The antenna configuration and the different radar modes are described.

  4. Intelligent radar data processing

    NASA Astrophysics Data System (ADS)

    Holzbaur, Ulrich D.

    The application of artificial intelligence principles to the processing of radar signals is considered theoretically. The main capabilities required are learning and adaptation in a changing environment, processing and modeling information (especially dynamics and uncertainty), and decision-making based on all available information (taking its reliability into account). For the application to combat-aircraft radar systems, the tasks include the combination of data from different types of sensors, reacting to electronic counter-countermeasures, evaluation of how much data should be acquired (energy and radiation management), control of the radar, tracking, and identification. Also discussed are related uses such as monitoring the avionics systems, supporting pilot decisions with respect to the radar system, and general applications in radar-system R&D.

  5. Meteorological radar calibration

    NASA Technical Reports Server (NTRS)

    Hodge, D. B.

    1978-01-01

    A meteorological radar calibration technique is developed. It is found that the integrated, range corrected, received power saturates under intense rain conditions in a manner analogous to that encountered for the radiometric path temperature. Furthermore, it is found that this saturation condition establishes a bound which may be used to determine an absolution radar calibration for the case of radars operating at attenuating wavelengths. In the case of less intense rainfall or for radars at nonattenuating wavelengths, the relationship for direct calibration in terms of an independent measurement of radiometric path temperature is developed. This approach offers the advantage that the calibration is in terms of an independent measurement of the rainfall through the same elevated region as that viewed by the radar.

  6. 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.

  7. GeoSAR: A Radar Terrain Mapping System for the New Millennium

    NASA Technical Reports Server (NTRS)

    Thompson, Thomas; vanZyl, Jakob; Hensley, Scott; Reis, James; Munjy, Riadh; Burton, John; Yoha, Robert

    2000-01-01

    GeoSAR Geographic Synthetic Aperture Radar) is a new 3 year effort to build a unique, dual-frequency, airborne Interferometric SAR for mapping of terrain. This is being pursued via a Consortium of the Jet Propulsion Laboratory (JPL), Calgis, Inc., and the California Department of Conservation. The airborne portion of this system will operate on a Calgis Gulfstream-II aircraft outfitted with P- and X-band Interferometric SARs. The ground portions of this system will be a suite of Flight Planning Software, an IFSAR Processor and a Radar-GIS Workstation. The airborne P-band and X-band radars will be constructed by JPL with the goal of obtaining foliage penetration at the longer P-band wavelengths. The P-band and X-band radar will operate at frequencies of 350 Mhz and 9.71 Ghz with bandwidths of either 80 or 160 Mhz. The airborne radars will be complemented with airborne laser system for measuring antenna positions. Aircraft flight lines and radar operating instructions will be computed with the Flight Planning Software The ground processing will be a two-step step process. First, the raw radar data will be processed into radar images and interferometer derived Digital Elevation Models (DEMs). Second, these radar images and DEMs will be processed with a Radar GIS Workstation which performs processes such as Projection Transformations, Registration, Geometric Adjustment, Mosaicking, Merging and Database Management. JPL will construct the IFSAR Processor and Calgis, Inc. will construct the Radar GIS Workstation. The GeoSAR Project was underway in November 1996 with a goal of having the radars and laser systems fully integrated onto the Calgis Gulfstream-II aircraft in early 1999. Then, Engineering Checkout and Calibration-Characterization Flights will be conducted through November 1999. The system will be completed at the end of 1999 and ready for routine operations in the year 2000.

  8. Darwin Infrared Nulling Interferometer Demonstrator

    NASA Astrophysics Data System (ADS)

    Vosteen, L. L. A.; Ahlers, B.

    2005-08-01

    Darwin is a space based interferometry mission1 of the European Space Agency (ESA) with the aim to detect and characterise earth-like planets outside our solar system. The current Darwin baseline consists of four spacecrafts (3 telescopes). Destructive interference of the starlight is required to allow detection of much fainter planet signals. The nulling ratio required is 105. For Darwin high requirements are set upon the wavefront quality of the beams. In order to be able to have destructive interference with a contrast factor of 105, a wavefront quality of ?/1400 (?=6 micrometer) is needed. With current and/or foreseen technology, it is not possible to produce the optical elements with sufficient quality to meet this requirement. This means it is vital to develop wavefront filter devices for Darwin. Most promising for this purpose are single mode fibres. For visible and near-infrared light commercially available single mode fibres are available, however they do not extend yet to wavelengths above 4 micrometer. To overcome this shortcoming new single mode fibres are developed (i.e. by Astrium and TNO/ University of Rennes) for the Darwin wavelength range (6-20 ?m). To characterize and test these fibres a system is designed allowing to determine the possible star light suppression with the fibre. This system is called "Darwin Infrared Nulling Interferometer Demonstrator" (DINID). The system is designed using the in-house knowledge from previous nulling set-ups in the visible and near-infrared wavelength range. It will permit to test fibres around 4 and 9 micrometer and includes an optical path difference control in order to compensate drifts. This paper describes the basis on which the set-up is designed.

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

    NASA Technical Reports Server (NTRS)

    Baker, John G.

    2012-01-01

    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.

  10. 4. VIEW NORTHEAST, radar tower (unknown function), prime search radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW NORTHEAST, radar tower (unknown function), prime search radar tower, emergency power building, and height finder radar tower - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  11. 5. VIEW EAST, height finder radar towers, radar tower (unknown ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. VIEW EAST, height finder radar towers, radar tower (unknown function), prime search radar tower, operations building, and central heating plant - Fort Custer Military Reservation, P-67 Radar Station, .25 mile north of Dickman Road, east of Clark Road, Battle Creek, Calhoun County, MI

  12. High resolution Fourier interferometer-spectrophotopolarimeter

    NASA Technical Reports Server (NTRS)

    Fymat, A. L. (Inventor)

    1976-01-01

    A high-resolution Fourier interferometer-spectrophotopolarimeter is provided using a single linear polarizer-analyzer the transmission axis azimuth of which is positioned successively in the three orientations of 0 deg, 45 deg, and 90 deg, in front of a detector; four flat mirrors, three of which are switchable to either of two positions to direct an incoming beam from an interferometer to the polarizer-analyzer around a sample cell transmitted through a medium in a cell and reflected by medium in the cell; and four fixed focussing lenses, all located in a sample chamber attached at the exit side of the interferometer. This arrangement can provide the distribution of energy and complete polarization state across the spectrum of the reference light entering from the interferometer; the same light after a fixed-angle reflection from the sample cell containing a medium to be analyzed; and the same light after direct transmission through the same sample cell, with the spectral resolution provided by the interferometer.

  13. An electronic Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Ji, Yang; Chung, Yunchul; Sprinzak, D.; Heiblum, M.; Mahalu, D.; Shtrikman, Hadas

    2003-03-01

    Double-slit electron interferometers fabricated in high mobility two-dimensional electron gases are powerful tools for studying coherent wave-like phenomena in mesoscopic systems. However, they suffer from low visibility of the interference patterns due to the many channels present in each slit, and from poor sensitivity to small currents due to their open geometry. Moreover, these interferometers do not function in high magnetic fields-such as those required to enter the quantum Hall effect regime-as the field destroys the symmetry between left and right slits. Here we report the fabrication and operation of a single-channel, two-path electron interferometer that functions in a high magnetic field. This device is the first electronic analogue of the optical Mach-Zehnder interferometer, and opens the way to measuring interference of quasiparticles with fractional charges. On the basis of measurements of single edge state and closed geometry transport in the quantum Hall effect regime, we find that the interferometer is highly sensitive and exhibits very high visibility (62%). However, the interference pattern decays precipitously with increasing electron temperature or energy. Although the origin of this dephasing is unclear, we show, via shot-noise measurements, that it is not a decoherence process that results from inelastic scattering events.

  14. Furnace control apparatus using polarizing interferometer

    DOEpatents

    Schultz, T.J.; Kotidis, P.A.; Woodroffe, J.A.; Rostler, P.S.

    1995-03-28

    A system for nondestructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading. 38 figures.

  15. Process control system using polarizing interferometer

    DOEpatents

    Schultz, T.J.; Kotidis, P.A.; Woodroffe, J.A.; Rostler, P.S.

    1994-02-15

    A system for nondestructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading. 38 figures.

  16. Process control system using polarizing interferometer

    DOEpatents

    Schultz, Thomas J. (Maumee, OH); Kotidis, Petros A. (Waban, MA); Woodroffe, Jaime A. (North Reading, MA); Rostler, Peter S. (Newton, MA)

    1994-01-01

    A system for non-destructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading.

  17. Furnace control apparatus using polarizing interferometer

    DOEpatents

    Schultz, Thomas J. (Maumee, OH); Kotidis, Petros A. (Waban, MA); Woodroffe, Jaime A. (North Reading, MA); Rostler, Peter S. (Newton, MA)

    1995-01-01

    A system for non-destructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading.

  18. The AEI 10 m prototype interferometer

    NASA Astrophysics Data System (ADS)

    Goßler, S.; Bertolini, A.; Born, M.; Chen, Y.; Dahl, K.; Gering, D.; Gräf, C.; Heinzel, G.; Hild, S.; Kawazoe, F.; Kranz, O.; Kühn, G.; Lück, H.; Mossavi, K.; Schnabel, R.; Somiya, K.; Strain, K. A.; Taylor, J. R.; Wanner, A.; Westphal, T.; Willke, B.; Danzmann, K.

    2010-04-01

    A 10 m prototype interferometer facility is currently being set up at the AEI in Hannover, Germany. The prototype interferometer will be housed inside a 100 m3 ultra-high vacuum envelope. Seismically isolated optical tables inside the vacuum system will be interferometrically interconnected via a suspension platform interferometer. Advanced isolation techniques will be used, such as inverted pendulums and geometrical anti-spring filters in combination with multiple-cascaded pendulum suspensions, containing an all-silica monolithic last stage. The light source is a 35 W Nd:YAG laser, geometrically filtered by passing it through a photonic crystal fibre and a rigid pre-modecleaner cavity. Laser frequency stabilisation will be achieved with the aid of a high finesse suspended reference cavity in conjunction with a molecular iodine reference. Coating thermal noise will be reduced by the use of Khalili cavities as compound end mirrors. Data acquisition and control of the experiments is based on the AdvLIGO digital control and data system. The aim of the project is to test advanced techniques for GEO 600 as well as to conduct experiments in macroscopic quantum mechanics. Reaching standard quantum-limit sensitivity for an interferometer with 100 g mirrors and subsequently breaching this limit, features most prominently among these experiments. In this paper we present the layout and current status of the AEI 10 m Prototype Interferometer project.

  19. Goldstone solar system radar

    NASA Technical Reports Server (NTRS)

    Jurgens, Raymond F.

    1988-01-01

    Planning, direction, experimental design, and coordination of data-acquisition and engineering activities in support of all Goldstone planetary radar astronomy were performed. This work demands familiarity with the various components of a planetary radar telescope (transmitter, receiver, antenna, computer hardware and software) as well as knowledge of how the entire system must function as a cohesive unit to meet the particular scientific objectives at hand in a given observation. Support radar data-processing facilities, currently being used for virtually all Goldstone data reduction includes: a VAX 11/780 computer system, an FPS 5210 array processor, terminals, tape drives, and image-display devices, as well as a large body of data-reduction software to accommodate the variety of data-acquisition formats and strategems. Successful 113-cm radar observation of Callisto and the near-Earth asteroid 1981 Midas and Goldstone/VLA radar observations of Saturn's rings were obtained. Quick-look verification programs from data taken with phase-coded cw (i.e., ranging) waveforms, applicable to Venus, the Moon, and small bodies were completed. Definition of scientific and engineering requirements on instrument performance, radar system configuration, and personnel, for all 1988 Goldstone radar investigations was accomplished.

  20. 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 ...

  1. Radar applications overview

    NASA Astrophysics Data System (ADS)

    Greenspan, Marshall

    1996-06-01

    During the fifty years since its initial development as a means of providing early warning of airborne attacks against allied countries during World War II, radar systems have developed to the point of being highly mobile and versatile systems capable of supporting a wide variety of remote sensing applications. Instead of being tied to stationary land-based sites, radar systems have found their way into highly mobile land vehicles as well as into aircraft, missiles, and ships of all sizes. Of all these applications, however, the most exciting revolution has occurred in the airborne platform arena where advanced technology radars can be found in all shapes and sizes...ranging from the large AWACS and Joint STARS long range surveillance and targeting systems to small millimeter wave multi-spectral sensors on smart weapons that can detect and identify their targets through the use of highly sophisticated digital signal processing hardware and software. This paper presents an overview of these radar applications with the emphasis on modern airborne sensors that span the RF spectrum. It will identify and describe the factors that influence the parameters of low frequency and ultra wide band radars designed to penetrate ground and dense foliage environments and locate within them buried mines, enemy armor, and other concealed or camouflaged weapons of war. It will similarly examine the factors that lead to the development of airborne radar systems that support long range extended endurance airborne surveillance platforms designed to detect and precision-located both small high speed airborne threats as well as highly mobile time critical moving and stationary surface vehicles. The mission needs and associated radar design impacts will be contrasted with those of radar systems designed for high maneuverability rapid acquisition tactical strike warfare platforms, and shorter range cued air-to-surface weapons with integral smart radar sensors.

  2. Radar Imaging of Mercury

    NASA Astrophysics Data System (ADS)

    Rice, M.; Harmon, J.

    2004-11-01

    Radar images of the entire Mercurian surface have been created using the Arecibo S-band radar (wavelength 12.6cm) and the long code delay-Doppler method. We have mapped the locations of midlatitude radar-bright craters across all longitudes, and in the Mariner-10 imaged hemisphere we find several disagreements between the features that appear freshest in the unpolarized radar images and those that have been classified as most recent in the USGS geologic maps. All USGS c5 craters correspond to bright features in our same-circular polarized radar images; however, several c1 and c2 craters have radar-bright deposits as well. In our radar maps of the Skinakas Basin region of the Mariner-10 unimaged hemisphere, we find little agreement between the proposed basin rim locations and the radar features. We have mapped the south polar region using new data from April 2004 with a sub-Earth latitude of 4.5S, this being our first chance to view the south pole since the Arecibo telescope upgrade. We confirm the locations of features seen in the pre-upgrade maps and we identify 15 new "ice" features extending to latitudes as low as 73S. All south polar features have circular polarization inversions (average SC/OC=1.38) that are consistent with volume scattering off cold-trapped volatiles. We also present a preliminary analysis of our August 2004 observations, including new radar images of "Feature C" (the strongest echo feature in the Mariner-10 unimaged hemisphere) and of the north polar region. This research was funded by the NSF as part of the Research Experiences for Undergraduates program.

  3. Fabry-Perot interferometer based Mie Doppler lidar for low tropospheric wind observation.

    PubMed

    Xia, Haiyun; Sun, Dongsong; Yang, Yuanhong; Shen, Fahua; Dong, Jingjing; Kobayashi, Takao

    2007-10-10

    Similar in principle to recent implementations of a lidar system at 355 nm [Opt. Lett. 25, 1231 (2000), Appl. Opt. 44, 6023 (2005)], an incoherent-detection Mie Doppler wind lidar at 1064 nm was developed and deployed in 2005 [Opt. Rev. 12, 409 (2005)] for wind measurements in the low troposphere, taking advantage of aerosol scattering for signal enhancement. We present a number of improvements made to the original 1064 nm system to increase its robustness for long-period operation. These include a multimode fiber for receiving the reference signal, a mode scrambler to allow uniform illumination over the Fabry-Perot interferometer, and a fast scannable Fabry-Perot interferometer for calibration and for the determination of outgoing laser frequency during the wind observation. With these improvements in stability, the standard deviation of peak transmission and FWHM of the Fabry-Perot interferometer was determined to be 0.49% and 0.36%, respectively. The lidar wind measurements were validated within a dynamic range of +/-40 m/s. Comparison experiments with both wind profiler radar and Vaisala wiresonde show good agreement with expected observation error. An example of 24 h continuous observations of wind field and aerosol backscatter coefficients in the boundary layer with 1 min and 30 m temporal and spatial resolution and 3 m/s tolerated wind velocity error is presented and fully demonstrates the stability and robustness of this lidar. PMID:17932519

  4. The Cassini Radar Investigation

    NASA Technical Reports Server (NTRS)

    Wall, Stephen D.

    2008-01-01

    The Cassini/Huygens Mission is a nineteen-year multinational project to design, construct and execute an investigation of the Saturn system, with emphasis on its largest moon, Titan. Titan's atmosphere is nearly opaque at optical wavelengths, so a Ku-band radar imaging system was required to map its surface. In this paper we describe the radar instrument, discuss some of the challenges to its design, and review its operating modes. We briefly summarize the surprises that the radar instrument has revealed while investigating Titan.

  5. Micropower impulse radar

    SciTech Connect

    Azevedo, S.; McEwan, T.E.

    1996-01-01

    Invented and developed at Lawrence Livermore National Laboratory is an inexpensive and highly sensitive, low-power radar system that produces and samples extremely short pulses of energy at the rate of 2 million per second. Called micropower impulse radar (MIR), it can detect objects at a greater variety of distances with greater sensitivity than conventional radar. Its origins in the Laboratory`s Laser Directorate stem from Nova`s transient digitizer. The MIR`s extraordinary range of applications include security, search and rescue, life support, nondestructive evaluation, and transportation.

  6. Asteroid radar astrometry

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.; Jurgens, R. F.; Rosema, K. D.; Winkler, R.; Yeomans, D. K.; Campbell, D. B.; Chandler, J. F.; Shapiro, I. I.; Hine, A. A.; Velez, R.

    1991-01-01

    Measurements of time delay and Doppler frequency are reported for asteroid-radar echoes obtained at Arecibo and Goldstone during 1980-1990. Radar astrometry is presented for 23 near-earth asteroids and three mainbelt asteroids. These measurements, which are orthogonal to optical, angular-position measurements, and typically have a fractional precision between 10 to the -5th and 10 to the -8th, permit significant improvement in estimates of orbits and hence in the accuracy of prediction ephemerides. Estimates are also reported of radar cross-section and circular polarization ratio for all asteroids observed astrometrically during 1980-1990.

  7. Radar investigation of asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1981-05-01

    Efforts were focused on: (1) acquisition of radar data at Arecibo; (2) examination of raw data; (3) reduction of the unmodulated data to background-free, calibrated spectra; (4) integration and coherent analyses of the phase-coded data; and (5) calculation of Doppler shifts and preliminary values for echo limb-to-limb bandwidths, radar cross sections, and circular polarization ratios. Asteroids observed to data have radar properties distinct from those of the rocky terrestrial planets and those of the icy Galilean satellites.

  8. Radar Remote Sensing

    NASA Technical Reports Server (NTRS)

    Rosen, Paul A.

    2012-01-01

    This lecture was just a taste of radar remote sensing techniques and applications. Other important areas include Stereo radar grammetry. PolInSAR for volumetric structure mapping. Agricultural monitoring, soil moisture, ice-mapping, etc. The broad range of sensor types, frequencies of observation and availability of sensors have enabled radar sensors to make significant contributions in a wide area of earth and planetary remote sensing sciences. The range of applications, both qualitative and quantitative, continue to expand with each new generation of sensors.

  9. Radar investigation of asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1984-07-01

    The initial radar observations of the mainbelt asteroids 9 Metis, 27 Euterpe, and 60 Echo are examined. For each target, data are taken simultaneously in the same sense of circular polarization as transmitted as well as in the opposite (OC) sense. Estimates of the radar cross sections provide estimates of the circular polarization ratio, and the normalized OC radar cross section. The circular polarization ratio, is comparable to values measured for other large S type asteroids and for a few much smaller, Earth approaching objects, most of the echo is due to single reflection backscattering from smooth surface elements.

  10. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1984-01-01

    The initial radar observations of the mainbelt asteroids 9 Metis, 27 Euterpe, and 60 Echo are examined. For each target, data are taken simultaneously in the same sense of circular polarization as transmitted as well as in the opposite (OC) sense. Estimates of the radar cross sections provide estimates of the circular polarization ratio, and the normalized OC radar cross section. The circular polarization ratio, is comparable to values measured for other large S type asteroids and for a few much smaller, Earth approaching objects, most of the echo is due to single reflection backscattering from smooth surface elements.

  11. 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

  12. Multitone harmonic radar

    NASA Astrophysics Data System (ADS)

    Mazzaro, Gregory J.; Martone, Anthony F.

    2013-05-01

    Nonlinear radar exploits the electronic response from a target whose reflected frequencies are different from those transmitted. Reception of frequencies that are not part of the transmitted probe distinguishes the received signal from a linear return produced by clutter and indicates the presence of electronics. Presented in this paper is a type of nonlinear radar that transmits multiple frequencies and listens for a harmonic of these frequencies as well as other frequencies near that harmonic. A laboratory test-bed has been constructed to demonstrate the multitone radar concept. Measurements of nonlinear responses from RF devices probed by multiple tones are reported.

  13. A microprogrammable radar controller

    NASA Technical Reports Server (NTRS)

    Law, D. C.

    1986-01-01

    The Wave Propagation Lab. has completed the design and construction of a microprogrammable radar controller for atmospheric wind profiling. Unlike some radar controllers using state machines or hardwired logic for radar timing, this design is a high speed programmable sequencer with signal processing resources. A block diagram of the device is shown. The device is a single 8 1/2 inch by 10 1/2 inch printed circuit board and consists of three main subsections: (1) the host computer interface; (2) the microprogram sequencer; and (3) the signal processing circuitry. Each of these subsections are described in detail.

  14. Full counting statistics of Majorana interferometers

    NASA Astrophysics Data System (ADS)

    Strübi, Grégory; Belzig, Wolfgang; Schmidt, Thomas L.; Bruder, Christoph

    2015-11-01

    We study the full counting statistics of interferometers for chiral Majorana fermions with two incoming and two outgoing Dirac fermion channels. In the absence of interactions, the FCS can be obtained from the 4×4 scattering matrix S that relates the outgoing Dirac fermions to the incoming Dirac fermions. After presenting explicit expressions for the higher-order current correlations for a modified Hanbury Brown-Twiss interferometer, we note that the cumulant-generating function can be interpreted such that unit-charge transfer processes correspond to two independent half-charge transfer processes, or alternatively, to two independent electron-hole conversion processes. By a combination of analytical and numerical approaches, we verify that this factorization property holds for a general SO(4) scattering matrix, i.e. for a general interferometer geometry.

  15. A heterodyne interferometer for angle metrology

    SciTech Connect

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

    2010-04-15

    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/{radical}(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 {mu}rad rms, respectively.

  16. 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

  17. Infrared phase-shifting digital interferometer

    NASA Astrophysics Data System (ADS)

    Chen, Jinbang; Chen, Lei; Huang, Shenwang; Jin, Guoyou

    1996-10-01

    This paper describes theory and performance of a self- developed IR phase-shifting digital interferometer which uses a CO2 laser as light source, this instrument comprises of a Fizeau interferometer whose aperture reaches (Phi) 250mm with accuracy better than (lambda) /50, and a Twyman spherical interferometer. Using piezoelectric transducer to shift reference mirror, phase measurement interferometry can be carried out as well as the temperature modulation of PEV target. A series of software packages used as wavefront fitting, image quality evaluation, are incorporated into the instrument. With the help of microcomputer, this interferometric system can measure refractive-index homogeneity of IR transmitting materials, wavefront error of IR optical system and surface quality of rough surface etc., which can all be shown by detailed data of optical path difference, vivid 2D contour and 3D surface.

  18. The Table Mountain 8-mm wavelength interferometer

    NASA Technical Reports Server (NTRS)

    Janssen, M. A.; Gary, B. L.; Gulkis, S.; Olsen, E. T.; Soltis, F. S.; Yamane, N. I.

    1979-01-01

    A two-element radio interferometer operating at 8.33-mm wavelength has been developed at the Jet Propulsion Laboratory's Table Mountain Observatory near Wrightwood, CA. The interferometer employs a 5.5-m and a 3-m diameter antenna on an east-west baseline of 60 or 120 m, yielding fringe spacings at transit of 28 or 14 arcsec, respectively. The broad intermediate-frequency bandpass of 100-350 MHz and the system noise temperature of 500 K provide high sensitivity for the measurement of continuum sources. The interferometer has been used for high-resolution studies of the planets and the sun, and it is currently being adapted to study solar flare emissions at high spatial and time resolution.

  19. Photothermal measurements with a Jamin interferometer

    NASA Astrophysics Data System (ADS)

    Cournoyer, Alain; Baulaigue, Pierre; Lazarides, Eric; Blancher, Henri; Bertrand, Lionel; Occelli, Roland

    1997-07-01

    We present a numerical study of the behavior of the signal in a photothermal experiment combining the mirage effect and a Jamin interferometer. Our analysis is limited to a square-pulse excitation by a weakly absorbed Gaussian pump laser beam with a large radius. We investigate the influence of three parameters: the time of illumination of the sample, the time of extinction of the pump beam, and the height of the probe-beam arm of the Jamin interferometer above the sample. We show that the path difference, which induces the variation of intensity at the output of the Jamin interferometer, is caused by both probe-beam deflection and temperature variation of the refractive index of air above the sample. The first effect is dominant for short times, and interferometry is a sensitive tool to monitor it.

  20. Modeling the Laser Interferometer Space Antenna Optics

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Pedersen, Tracy R.; McNamara, paul

    2005-01-01

    The Laser Interferometer Space Antenna (LISA), shown below, will detect gravitational waves produced by objects such as binary black holes or objects falling into black holes (extreme mass ratio inspirals) over a frequency range of l0(exp -4) to 0.1 Hz. Within the conceptual frame work of Newtonian physics, a gravitational wave produces a strain, (Delta)l/l, with magnitudes of the order of Earth based gravitational wave detectors, such as the Laser Interferometer Gravitational-Wave Observatory (LIGO) project, use Michelson interferometers with arm lengths l = 4 km to detect these strains. Earth induced seismic noise limits ground-based instruments detecting gravitational waves with frequencies lower than approx. 1 Hz.

  1. Martin-Puplett interferometer: an analysis.

    PubMed

    Lambert, D K; Richards, P L

    1978-05-15

    A detailed analysis is presented of the Michelson polarizing interferometer suggested by Martin and Puplett. This instrument has many favorable properties for use as a far ir Fourier spectrometer. The effect of misalignments and imperfections of the optical components on the instrumental performance is calculated. Based on these results, we give a method of aligning the interferometer which optimizes its performance. In addition, this instrument may be used to measure the optical transfer function of a component in the output beam as a function of both spatial and optical frequency. A procedure is described by which this may be done. PMID:20198028

  2. Computer control of a far infrared interferometer

    NASA Technical Reports Server (NTRS)

    Breecher, J.

    1977-01-01

    A simple interface has been designed for the automatic control and data collection from a Grubb Parsons Mark III cube interferometer. A computer is used to automatically step the movable mirror on the interferometer. Data may be directly input into the computer for immediate transformation or stored for later analysis via a fast Fourier transformation. The interface is based on a commercial analog-to-digital converter having a parallel-to-serial data converter. The device can also display ASCII characters sent from the computer in parallel binary code. The system is applicable to recording interferograms having long time durations and to measuring multiple interferograms for statistical averaging.

  3. Self-referenced interferometer for cylindrical surfaces.

    PubMed

    Šarbort, Martin; Řeřucha, Šimon; Holá, Miroslava; Buchta, Zdeněk; Lazar, Josef

    2015-11-20

    We present a new interferometric method for shape measurement of hollow cylindrical tubes. We propose a simple and robust self-referenced interferometer where the reference and object waves are represented by the central and peripheral parts, respectively, of the conical wave generated by a single axicon lens. The interferogram detected by a digital camera is characterized by a closed-fringe pattern with a circular carrier. The interference phase is demodulated using spatial synchronous detection. The capabilities of the interferometer are experimentally tested for various hollow cylindrical tubes with lengths up to 600 mm. PMID:26836560

  4. Topography of the lunar poles from radar interferometry: a survey of cold trap locations.

    PubMed

    Margot, J L; Campbell, D B; Jurgens, R F; Slade, M A

    1999-06-01

    Detailed topographic maps of the lunar poles have been obtained by Earth-based radar interferometry with the 3.5-centimeter wavelength Goldstone Solar System Radar. The interferometer provided maps 300 kilometers by 1000 kilometers of both polar regions at 150-meter spatial resolution and 50-meter height resolution. Using ray tracing, these digital elevation models were used to locate regions that are in permanent shadow from solar illumination and may harbor ice deposits. Estimates of the total extent of shadowed areas poleward of 87.5 degrees latitude are 1030 and 2550 square kilometers for the north and south poles, respectively. PMID:10356393

  5. Aircraft radar antennas

    NASA Astrophysics Data System (ADS)

    Schrank, Helmut E.

    1987-04-01

    Many changes have taken place in airborne radar antennas since their beginnings over forty years ago. A brief historical review of the advances in technology is presented, from mechanically scanned reflectors to modern multiple function phased arrays. However, emphasis is not on history but on the state-of-the-art technology and trends for future airborne radar systems. The status of rotating surveillance antennas is illustrated by the AN/APY-1 Airborne Warning and Control System (AWACS) slotted waveguide array, which achieved a significant breakthrough in sidelobe suppression. Gimballed flat plate arrays in nose radomes are typified by the AN/APG-66 (F-16) antenna. Multifunction phased arrays are presented by the Electronically Agile Radar (EAR) antenna, which has achieved significant advances in performance versatility and reliability. Trends toward active aperture, adaptive, and digital beamforming arrays are briefly discussed. Antennas for future aircraft radar systems must provide multiple functions in less aperture space, and must perform more reliably.

  6. RADAR performance experiments

    NASA Technical Reports Server (NTRS)

    Leroux, C.; Bertin, F.; Mounir, H.

    1991-01-01

    Theoretical studies and experimental results obtained at Coulommiers airport showed the capability of Proust radar to detect wind shears, in clear air condition as well as in presence of clouds or rain. Several examples are presented: in a blocking highs situation an atmospheric wave system at the Brunt-Vaisala frequency can be clearly distinguished; in a situation of clouds without rain the limit between clear air and clouds can be easily seen; and a windshear associated with a gust front in rainy conditions is shown. A comparison of 30 cm clear air radar Proust and 5 cm weather Doppler radar Ronsard will allow to select the best candidate for wind shear detection, taking into account the low sensibility to ground clutter of Ronsard radar.

  7. 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.

  8. Radar investigation of asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    For 80 Sappho, 356 Liguria, 694 Ekard, and 2340 Hathor, data were taken simultaneously in the same sense of circular polarization as transmitted (SC) as well as in the opposite (OC) sense. Graphs show the average OC and SC radar echo power spectra soothed to a resolution of EFB Hz and plotted against Doppler frequency. Radar observations of the peculiar object 2201 Oljato reveal an unusual set of echo power spectra. The albedo and polarization ratio remain fairly constant but the bandwidths range from approximately 0.8 Hz to 1.4 Hz and the spectral shapes vary dramatically. Echo characteristics within any one date's approximately 2.5-hr observation period do not fluctuate very much. Laboratory measurements of the radar frequency electrical properties of particulate metal-plus-silicate mixtures can be combined with radar albedo estimates to constrain the bulk density and metal weight, fraction in a hypothetical asteroid regolith having the same particle size distribution as lab samples.

  9. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1983-01-01

    For 80 Sappho, 356 Liguria, 694 Ekard, and 2340 Hathor, data were taken simultaneously in the same sense of circular polarization as transmitted (SC) as well as in the opposite (OC) sense. Graphs show the average OC and SC radar echo power spectra soothed to a resolution of EFB Hz and plotted against Doppler frequency. Radar observations of the peculiar object 2201 Oljato reveal an unusual set of echo power spectra. The albedo and polarization ratio remain fairly constant but the bandwidths range from approximately 0.8 Hz to 1.4 Hz and the spectral shapes vary dramatically. Echo characteristics within any one date's approximately 2.5-hr observation period do not fluctuate very much. Laboratory measurements of the radar frequency electrical properties of particulate metal-plus-silicate mixtures can be combined with radar albedo estimates to constrain the bulk density and metal weight, fraction in a hypothetical asteroid regolith having the same particle size distribution as lab samples.

  10. Downhole pulse radar

    DOEpatents

    Chang, Hsi-Tien

    1987-09-28

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole. 7 figs.

  11. Downhole pulse radar

    DOEpatents

    Chang, Hsi-Tien

    1989-01-01

    A borehole logging tool generates a fast rise-time, short duration, high peak-power radar pulse having broad energy distribution between 30 MHz and 300 MHz through a directional transmitting and receiving antennas having barium titanate in the electromagnetically active region to reduce the wavelength to within an order of magnitude of the diameter of the antenna. Radar returns from geological discontinuities are sampled for transmission uphole.

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

    SciTech Connect

    Bach, Roger; Batelaan, Herman; Gronniger, Glen

    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.

  13. 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.

  14. Optical fiber voltage sensor based on Michelsion interferometer using Fabry-Perot demodulation interferometer

    NASA Astrophysics Data System (ADS)

    Chen, Xinwei; He, Shengnan; Li, Dandan; Wang, Kai; Fan, Yan'en; Wu, Shuai

    2014-11-01

    We present an optical fiber voltage sensor by Michelsion interferometer (MI) employing a Fabry-Perot (F-P) interferometer and the DC phase tracking (DCPT) signal processing method. By mounting a MI fabricated by an optical fiber coupler on a piezoelectric (PZT) transducer bar, a dynamic strain would be generated to change the optical path difference (OPD) of the interferometer when the measured voltage was applied on the PZT. Applying an F-P interferometer to demodulate the optical intensity variation output of the MI, the voltage can be obtained. The experiment results show that the relationship between the optical intensity variation and the voltage applied on the PZT is approximately linear. Furthermore, the phase generate carrier (PGC) algorithm was applied to demodulate the output of the sensor also.

  15. 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.

  16. The StarLight Space Interferometer

    NASA Technical Reports Server (NTRS)

    Folkner, William; Shao, Michael; Gorham, Peter

    2004-01-01

    Two papers describe the StarLight space interferometer a Michelson interferometer that would be implemented by two spacecraft flying in formation. The StarLight formation flying interferometer project has been testing and demonstrating engineering concepts for a new generation of space interferometers that would be employed in a search for extrasolar planets and in astrophysical investigations. As described in the papers, the original StarLight concept called for three spacecraft, and the main innovation embodied is a modification that makes it possible to reduce complexity by eliminating the third spacecraft. The main features of the modification are (1) introduction of an optical delay line on one spacecraft and (2) controlling the flying formation such that the two spacecraft are located at two points along a specified parabola so as to define the required baseline of specified length (which could be varied up to 125 m) perpendicular to the axis of the parabola. One of the papers presents a detailed description of the optical layout and discusses computational modeling of the performance; the other paper presents an overview of the requirements for operation and design, the overall architecture, and subsystems.

  17. A microwave interferometer to measure transient properties

    SciTech Connect

    Warthen, B.J.; Luther, G.G.

    1982-12-31

    A simple K-band microwave interferometer has been developed at the Los Alamos National Laboratory to measure various transient properties in both energetic (high explosive) and passive (grout and Teflon) materials. The interferometer measures the position as a function of time of either a dielectric discontinuity, i.e., a shock front, or the position as a function of time of a conducting surface such as the detonation wave in a high explosive. By embedding a reflector in a dielectric material, both the particle velocity and the shock velocity may be measured at the same time and in the same place. The interferometer is constructed (with slight modifications) of commercially available microwave components. The total material cost for a complete working instrument is a few hundred dollars. Details of the construction will be given. As an example of the range of uses of the interferometer, it has been used to measure the detonation-to-deflagration transition in HMX and the shock properties of the grout in a nuclear test in Nevada. Data on these and other experiments are presented.

  18. Differential Phase Mode with the Keck Interferometer

    NASA Technical Reports Server (NTRS)

    Akeson, Rachel; Swain, Mark

    2000-01-01

    We describe the differential phase mode of the Keck Interferometer. The scientific goal of this mode is the direct detection and spectroscopic characterization of hot, Jupiter mass planets. We describe the differential phase effect, the basic observational mode, and the expected differential phase signatures for the extrasolar planets discovered through radial velocity searches.

  19. Lock acquisition in resonant optical interferometers

    NASA Astrophysics Data System (ADS)

    Evans, Matthew John

    2002-08-01

    The LIGO (Laser Interferometric Gravitational-wave Observatory) project, and other projects around the world, are currently planning to use long-baseline (>1 km) interferometers to directly detect gravitational radiation from astrophysical sources. In this work we present a framework for lock acquisition, the process by which an initially uncontrolled resonant interferometer is brought to its operating point. Our approach begins with the identification of a path which takes the detector from the uncontrolled state to the operational state. The properties of the detector's outputs along this path, embodied in the sensing matrix, must be determined and parameterized in terms of measureables. Finally, a control system which can compute the inverse of the sensing matrix, apply it to the incoming signals, and make the resulting signals available for feedback is needed to close the control loop. This formalism was developed and explored extensively in simulation and was subsequently applied to the LIGO interferometers. Results were in agreement with expectation within error, typically ±20% on the sensing matrix elements, and the method proved capable of bringing a high-finesse power-recycled Fabry-Perot-Nlichelson interferometer (a LIGO detector) to its operating point.

  20. A Microwave Interferometer on an Air Track.

    ERIC Educational Resources Information Center

    Polley, J. Patrick

    1993-01-01

    Uses an air track and microwave transmitters and receivers to make a Michelson interferometer. Includes three experiments: (1) measuring the wavelength of microwaves, (2) measuring the wavelength of microwaves by using the Doppler Effect, and (3) measuring the Doppler shift. (MVL)

  1. Development of the test interferometer for ALMA

    NASA Astrophysics Data System (ADS)

    Olguin, R.; Shen, T.; Brito, R.; Saez, A.; Soto, R.; Asayama, S.; Follert, C.; Knee, L.; Quintana, A.; Rabanus, D.; Reynolds, E.; Saez, N.; Sepulveda, J.

    2012-09-01

    The ALMA Test Interferometer appeared as an infrastructure solution to increase both ALMA time availability for science activities and time availability for Software testing and Engineering activities at a reduced cost (<30000K USD) and a low setup time of less than 1 hour. The Test Interferometer could include up to 16 Antennas when used with only AOS resources and a possible maximum of 4 Antennas when configured using Correlator resources at OSF. A joined effort between ADC and ADE-IG took the challenge of generate the Test Interferometer from an already defined design for operations which imposed a lot of complex restrictions on how to implement it. Through and intensive design and evaluation work it was determined that is possible to make an initial implementation using the ACA Correlator and now it is also being tested the feasibility to implement the Testing Interferometer connecting the Test Array at AOS with Correlator equipment installed at the OSF, separated by 30 km. app. Lastly, efforts will be done to get interferometry between AOS and OSF Antennas with a baseline of approximately 24 km.

  2. Michelson Interferometer for Your Kitchen Table

    NASA Astrophysics Data System (ADS)

    Vollmer, M.; Möllmann, K.-P.

    2008-02-01

    Interferometry and related technologies are well known and often used in science and industry. Examples are measurements of small distances, determining the index of refraction of gases, testing the optical quality of optical components (e.g., lenses) and measuring the surface roughness with optical profilometers (which are more or less just computerized white light Michelson interferometers).

  3. Berkeley heterodyne interferometer. [for IR stellar observations

    NASA Technical Reports Server (NTRS)

    Betz, A.

    1975-01-01

    A prototype heterodyne stellar interferometer has been built in order to demonstrate the feasibility of heterodyne techniques in measuring angular diameters of bright infrared stars. The first system tests were performed in December 1972. Attention is given to investigations concerning the possibility that optical air turbulence within the structure of the solar telescope employed can possibly destroy the phase coherence of the fringe signals.

  4. The effect of rotations on Michelson interferometers

    SciTech Connect

    Maraner, Paolo

    2014-11-15

    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. - Highlights: • Rotations induce a phase shift in Michelson interferometers. • Earth’s rotation induces a constant bias in Michelson interferometers. • Michelson interferometers can be used to sense center and radius of rotations.

  5. 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.

  6. The Mask Designs for Space Interferometer Mission (SIM)

    NASA Technical Reports Server (NTRS)

    Wang, Xu

    2008-01-01

    The Space Interferometer Mission (SIM) consists of three interferometers (science, guide1, and guide2) and two optical paths (metrology and starlight). The system requirements for each interferometer/optical path combination are different and sometimes work against each other. A diffraction model is developed to design and optimize various masks to simultaneously meet the system requirements of three interferometers. In this paper, the details of this diffraction model will be described first. Later, the mask design for each interferometer will be presented to demonstrate the system performance compliance. In the end, a tolerance sensitivity study on the geometrical dimension, shape, and the alignment of these masks will be discussed.

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

    SciTech Connect

    Wu Chienming

    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.

  8. X-ray multilens interferometer based on Si refractive lenses

    NASA Astrophysics Data System (ADS)

    Snigirev, A.; Snigireva, I.; Lyubomirskiy, M.; Kohn, V.; Yunkin, V.; Kuznetsov, S.

    2014-09-01

    We report a multilens X-ray interferometer consisting of six parallel arrays of planar compound refractive lenses. The main concept of new interferometer is based on the same principle such a bilens interferometer. The interference fringe pattern produced by the multilens interferometer was described by Talbot imaging formalism. A theoretical analysis of the interference pattern formation was carried out and corresponding computer simulations were performed. The proposed multilens interferometer was experimentally tested at ID06 ESRF beamline in the X-ray energy range from 10 to 30 keV. Experimentally recorded fractional Talbot images are in a good agreement with computer calculations.

  9. Atomic multiwave interferometer for Aharonov-Casher-phase measurements

    NASA Astrophysics Data System (ADS)

    Zhou, Min-Kang; Zhang, Ke; Duan, Xiao-Chun; Ke, Yi; Shao, Cheng-Gang; Hu, Zhong-Kun

    2016-02-01

    We present an atomic multiwave interferometer with magnetic sublevels to precisely determine the Aharonov-Casher (AC) geometric phase. Simulations show that this interferometer has sharper fringes than a normal two-wave interferometer, which means a higher phase resolution can be achieved. Moreover, atoms evolving in a single hyperfine structure state make the interferometer insensitive to the dc Stark phase shift. This dc Stark shift is one of the main noise sources in AC phase measurements. The constraint of the photon rest mass is also discussed when using this atomic interferometer to measure the Aharonov-Casher phase.

  10. 66. VIEW SHOWING HOLD FOR RADAR CABLES AT RADAR SITE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    66. VIEW SHOWING HOLD FOR RADAR CABLES AT RADAR SITE, LOOKING NORTH Everett Weinreb, photographer, March 1988 - Mount Gleason Nike Missile Site, Angeles National Forest, South of Soledad Canyon, Sylmar, Los Angeles County, CA

  11. Radar Refractivity Retrieval: Validation and Application to Short-Term Forecasting.

    NASA Astrophysics Data System (ADS)

    Weckwerth, Tammy M.; Pettet, Crystalyne R.; Fabry, Frédéric; Park, Shinju; Lemone, Margaret A.; Wilson, James W.

    2005-03-01

    This study will validate the S-band dual-polarization Doppler radar (S-Pol) radar refractivity retrieval using measurements from the International H2O Project conducted in the southern Great Plains in May-June 2002. The range of refractivity measurements during this project extended out to 40-60 km from the radar. Comparisons between the radar refractivity field and fixed and mobile mesonet refractivity values within the S-Pol refractivity domain show a strong correlation. Comparisons between the radar refractivity field and low-flying aircraft also show high correlations. Thus, the radar refractivity retrieval provides a good representation of low-level atmospheric refractivity. Numerous instruments that profile the temperature and moisture are also compared with the refractivity field. Radiosonde measurements, Atmospheric Emitted Radiance Interferometers, and a vertical-pointing Raman lidar show good agreement, especially at low levels. Under most daytime summertime conditions, radar refractivity measurements are representative of an 250-m-deep layer. Analyses are also performed on the utility of refractivity for short-term forecasting applications. It is found that the refractivity field may detect low-level boundaries prior to the more traditional radar reflectivity and Doppler velocity fields showing their existence. Data from two days on which convection initiated within S-Pol refractivity range suggest that the refractivity field may exhibit some potential utility in forecasting convection initiation. This study suggests that unprecedented advances in mapping near-surface water vapor and subsequent improvements in predicting convective storms could result from implementing the radar refractivity retrieval on the national network of operational radars.

  12. How Can the TanDEM-X Digital Elevation Model Support Terrestrial Impact Crater Studies?

    NASA Astrophysics Data System (ADS)

    Gottwald, M.; Fritz, T.; Breit, H.; Schaettler, B.; Harris, A.

    2015-09-01

    The German Aerospace Center operated the X-band radar satellites TerraSAR-X and TanDEM-X as a single-pass SAR interferometer. Data acquisition occurred over the entire land surface for the generation of a very high quality digital elevation model.

  13. The TanDEM-X DEM — Status of the New Dataset for Studying Topography of the Global Impact Crater Record

    NASA Astrophysics Data System (ADS)

    Gottwald, M.; Fritz, T.; Breit, H.; Schaettler, B.; Harris, A.

    2015-07-01

    In the TanDEM-X mission two X-band radar satellites were operated as a single-pass SAR interferometer. From the acquired data a new digital elevation model is being generated. We report on the capabilities of this DEM for impact crater studies.

  14. A barrier radar concept

    NASA Astrophysics Data System (ADS)

    Marshall, J.; Ball, C.; Weissman, I.

    A description is given of a low power, light-weight radar that can be quickly set up and operated on batteries for extended periods of time to detect airborne intruders. With low equipment and operating costs, it becomes practical to employ a multiplicity of such radars to provide an unbroken intrusion fence over the desired perimeter. Each radar establishes a single transmitted fan beam extending vertically from horizon to horizon. The beam is generated by a two-face array antenna built in an A-frame configuration and is shaped, through phasing of the array elements, to concentrate the transmitter power in a manner consistent with the expected operating altitude ceiling of the targets of interest. The angular width of this beam in the dimension transverse to the fan depends on the radar transmission frequency and the antenna aperture dimension, but is typically wide enough so that a target at the maximum altitude or range will require tens of seconds to pass through the beam. A large number of independent samples of radar data will thus be available to provide many opportunities for target detection.

  15. Enhanced Mars Radar Observations with the Goldstone Solar System Radar

    NASA Astrophysics Data System (ADS)

    Haldemann, A. F. C.; Jurgens, R. F.; Anderson, F. S.; Slade, M. A.

    2000-10-01

    The Goldstone Solar System Radar (GSSR) has successfully collected radar echo data from Mars over the past 30 years. GSSR radar data were critical in assessing the Viking Lander 1 as well as the Mars Pathfinder landing sites. A reprocessing to common format of the last ten years worth of GSSR Mars delay-Doppler sub-Earth radar track profiles was recently completed in aid of landing site characterization. The radar data obtained since 1988 by the GSSR comprise some 73 delay-Doppler radar tracks. Sixteen of those tracks also have interferometric radar data, which has never been processed, because the signal to noise is insufficient to constrain both the phases and the radar scattering parameters. The new topographic data from the Mars Orbiter Laser Altimeter on the Mars Global Surveyor spacecraft offer the best means to finally make radar maps that extend the radar properties coverage some 3 to 4 degrees beyond the sub-Earth radar track. This would be a significant expansion of the dataset, and is all the more warranted as the radar spatial resolution improves away from the sub-Earth track. At the outer edges the radar resolution cell is of the same order of size as the landing site ellipses for future mission (approximately 20 km diameter). Initial results of processing the interferometric data will be presented at the meeting. The 2001 Mars opposition offers an opportunity to fill in some areas where radar data are lacking in the current dataset. We are planning 18 radar experiments from May through July of 2001. The goal of the observations will be to provide new, interferometric, improved-spatial-resolution radar data over the equatorial regions (latitudes -2 to +7) of Mars, in particular over the so-called Hematite Site in Sinus Meridiani. This work was carried out at the Jet Propulsion Laboratory, a division of the California Institute of Technology, with funding from the Mars Data Analysis Program of NASA OSS.

  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. A compact semiconductor digital interferometer and its applications

    NASA Astrophysics Data System (ADS)

    Britsky, Oleksander I.; Gorbov, Ivan V.; Petrov, Viacheslav V.; Balagura, Iryna V.

    2015-05-01

    The possibility of using semiconductor laser interferometers to measure displacements at the nanometer scale was demonstrated. The creation principles of miniature digital Michelson interferometers based on semiconductor lasers were proposed. The advanced processing algorithm for the interferometer quadrature signals was designed. It enabled to reduce restrictions on speed of measured movements. A miniature semiconductor digital Michelson interferometer was developed. Designing of the precision temperature stability system for miniature low-cost semiconductor laser with 0.01ºС accuracy enabled to use it for creation of compact interferometer rather than a helium-neon one. Proper firmware and software was designed for the interferometer signals real-time processing and conversion in to respective shifts. In the result the relative displacement between 0-500 mm was measured with a resolution of better than 1 nm. Advantages and disadvantages of practical use of the compact semiconductor digital interferometer in seismometers for the measurement of shifts were shown.

  19. 33. Perimeter acquisition radar building room #320, perimeter acquisition radar ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. Perimeter acquisition radar building room #320, perimeter acquisition radar operations center (PAROC), contains the tactical command and control group equipment required to control the par site. Showing spacetrack monitor console - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  20. Phase modulating the Urbana radar

    NASA Technical Reports Server (NTRS)

    Herrington, L. J., Jr.; Bowhill, S. A.

    1983-01-01

    The design and operation of a switched phase modulation system for the Urbana Radar System are discussed. The system is implemented and demonstrated using a simple procedure. The radar system and circuits are described and analyzed.

  1. Radar data smoothing filter study

    NASA Technical Reports Server (NTRS)

    White, J. V.

    1984-01-01

    The accuracy of the current Wallops Flight Facility (WFF) data smoothing techniques for a variety of radars and payloads is examined. Alternative data reduction techniques are given and recommendations are made for improving radar data processing at WFF. A data adaptive algorithm, based on Kalman filtering and smoothing techniques, is also developed for estimating payload trajectories above the atmosphere from noisy time varying radar data. This algorithm is tested and verified using radar tracking data from WFF.

  2. An active radar calibration target

    NASA Technical Reports Server (NTRS)

    Brunfeldt, D. R.; Ulaby, F. T.

    1982-01-01

    An active radar calibrator (ARC), consisting of a receive antenna and a transmit antenna with an RF amplifier in between, is proposed as a tool for conducting high-precision calibration measurements of radar systems. The ARC can be designed to have a large radar cross-section with a broad pattern. Its major advantages over passive reflectors are its small physical size and its suitability for calibrating radars operating in a cross-polarized antenna configuration.

  3. Radar detection of phobos.

    PubMed

    Ostro, S J; Jurgens, R F; Yeomans, D K; Standish, E M; Greiner, W

    1989-03-24

    Radar echoes from the martian satellite Phobos provide information about that object's surface properties at scales near the 3.5-cm observing wavelength. Phobos appears less rough than the moon at centimeter-to-decimeter scales. The uppermost few decimeters of the satellite's regolith have a mean bulk density within 20% of 2.0 g cm(-3). The radar signature of Phobos (albedo, polarization ratio, and echo spectral shape) differs from signatures measured for small, Earth-approaching objects, but resembles those of large (>/=100-km), C-class, mainbelt asteroids. PMID:17847261

  4. Radar detection of Phobos

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.; Jurgens, R. F.; Yeomans, D. K.; Standish, E. M.; Greiner, W.

    1989-01-01

    Radar echoes from the martian satellite Phobos provide information about that object's surface properties at scales near the 3.5-cm observing wavelength. Phobos appears less rough than the moon at centimeter-to-decimeter scales. The uppermost few decimeters of the satellite's regolith have a mean bulk density within 20 percent of 2.0 g/cu cm. The radar signature of Phobos (albedo, polarization ratio, and echo spectral shape) differs from signatures measured for small, earth-approaching objects, but resembles those of large (greater than 100-km), C-class, mainbelt asteroids.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. A continuous cold atomic beam interferometer

    SciTech Connect

    Xue, Hongbo; Feng, Yanying Yan, Xueshu; Jiang, Zhikun; Chen, Shu; Wang, Xiaojia; Zhou, Zhaoying

    2015-03-07

    We demonstrate an atom interferometer that uses a laser-cooled continuous beam of {sup 87}Rb atoms having velocities of 10–20 m/s. With spatially separated Raman beams to coherently manipulate the atomic wave packets, Mach–Zehnder interference fringes are observed at an interference distance of 2L = 19 mm. The apparatus operates within a small enclosed area of 0.07 mm{sup 2} at a bandwidth of 190 Hz with a deduced sensitivity of 7.8×10{sup −5} rad/s/√(Hz) for rotations. Using a low-velocity continuous atomic source in an atom interferometer enables high sampling rates and bandwidths without sacrificing sensitivity and compactness, which are important for applications in real dynamic environments.

  11. A multipulsed dynamic diffraction moire interferometer

    NASA Astrophysics Data System (ADS)

    Deason, V. A.; Ward, M. B.

    A system capable of generating several tens of diffraction moire interferograms at rates on the order of 1 MHz is described. The interferometer consists of a specially modified, segmented ruby rod laser capable of producing a long train of 40-mJ pulses each with a width on the order of 20 to 50 ns. The interferograms are recorded on film using a high speed turbine camera capable of 2,000,000 frames per second for a total record of 80 frames. The interferometer is used in conjunction with any of several devices for impulsively loading a variety of materials so as to study dynamic material deformation, fracture, delamination, or other response to dynamic stress. This apparatus is the latest in a series of dynamic diffraction moire systems built at the Idaho National Engineering Laboratory. Dynamic moire studies of Colorado oil shale are briefly discussed.

  12. A multipulsed dynamic diffraction moire interferometer

    SciTech Connect

    Deason, V.A.; Ward, M.B.

    1989-01-01

    A system capable of generating several tens of diffraction moire interferograms at rates on the order of 1 MHz is described. The interferometer consists of a specially modified, segmented ruby rod laser capable of producing a long train of 40-mJ pulses each with a width on the order of 20 to 50 ns. The interferograms are recorded on film using a high speed turbine camera capable of 2,000,000 frames per second for a total record of 80 frames. The interferometer is used in conjunction with any of several devices for impulsively loading a variety of materials so as to study dynamic material deformation, fracture, delamination, or other response to dynamic stress. This apparatus is the latest in a series of dynamic diffraction moire systems built at the Idaho National Engineering Laboratory. Dynamic moire studies of Colorado oil shale are briefly discussed. 2 refs., 3 figs.

  13. Heterodyne interferometer with unequal path lengths

    SciTech Connect

    Kumar, Deepak; Bellan, Paul M.

    2006-08-15

    Laser interferometry is an extensively used diagnostic for plasma experiments. Existing plasma interferometers are designed on the presumption that the scene and reference beam path lengths have to be equal, a requirement that is costly in both the number of optical components and the alignment complexity. It is shown here that having equal path lengths is not necessary, instead, what is required is that the path length difference be an even multiple of the laser cavity length. This assertion has been verified in a heterodyne laser interferometer that measures typical line-average densities of {approx}10{sup 21}/m{sup 2} with an error of {approx}10{sup 19}/m{sup 2}.

  14. Analysis of atom-interferometer clocks

    NASA Astrophysics Data System (ADS)

    Peil, Steven; Ekstrom, Christopher R.

    2014-01-01

    We analyze the nature and performance of clocks formed by stabilizing an oscillator to the phase difference between two paths of an atom interferometer. The phase evolution has been modeled as being driven by the proper-time difference between the two paths, although it has an ambiguous origin in the nonrelativistic limit and it requires a full quantum-field-theory treatment in the general case. We present conditions for identifying deviations from the nonrelativistic limit as a way of testing the proper-time-driven phase evolution model. We show that the system performance belies the premise that an atom-interferometer clock is referenced to a divided-down Compton oscillation, and we suggest that this implies there is no physical oscillation at the Compton frequency.

  15. Phase-shifting point diffraction interferometer

    DOEpatents

    Medecki, Hector

    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.

  16. 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.

  17. Adaptive optics for fiber-fed interferometers

    NASA Astrophysics Data System (ADS)

    Hart, Michael; Stalcup, Thomas; Durney, Olivier; Emerson, Nicholas; Powell, Keith; Ward, Michael; Feller, Greg; Kendrick, Rick; Mason, James; Bold, Matthew; Dewell, Larry; Kubo, Tracy

    2013-05-01

    Optical interferometry is a cost-effective means to extend the resolving power of astronomical instruments. Typically, the light from separate small and movable telescopes is brought through vacuum pipes to a central beam combiner. We are developing a new generation of AO systems to enhance the performance of interferometers in which the vacuum lines are replaced with optical fibers. The AO, included on each of the telescopes, concentrates light on the fiber inputs to achieve the greatest optical throughput. We describe the design approach to the AO systems, how their requirements differ from those of a traditional system, and how the addition of AO enables further enhancements to the design of optical interferometers.

  18. An adaptive interferometer for optical testing .

    NASA Astrophysics Data System (ADS)

    Pariani, G.; Colella, L.; Bertarelli, C.; Aliverti, M.; Riva, M.; Bianco, A.

    Interferometry is a well-established technique to test optical elements. However, its use is challenging in the case of free-form and aspheric elements, due to the lack of the reference optics. The proposed idea concerns the development of a versatile interferometer, where its reference arm is equipped with a reprogrammable Computer Generated Hologram. This principle takes advantage from our study on photochromic materials for optical applications, which shows a strong and reversible modulation of transparency in the visible region. The encoding of the desired hologram can be done off-line, or directly into the interferometer, and different patterns may be realized sequentially after the erasing of the previous hologram. We report on the present state of the research and on the future perspectives. skip=5pt

  19. A double image Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Ramadan, W. A.; El-Tawargy, A. S.

    2015-02-01

    In this paper, we present a modified version of the Mach-Zehnder interferometer. An arrangement of two linear polarizers and a wave rotator has been inserted in the light's path. Using this new arrangement, we are able to obtain a double image of a birefringent fibre. This double image records the shifts of the Mach-Zehnder's fringes for the light vibrating parallel and perpendicular to the fibre's axis in the same image. Moreover, by controlling the beam splitters, we are able to get an overlap between two images of the fibre and to directly observe an image describing the birefringence of the investigated fibre. This new arrangement has been applied to three polypropylene fibres and a graded-index FOS optical fibre in order to demonstrate its validity and powerful ability for monitoring the direct birefringence. A set of images of the investigated samples is presented and compared with images obtained using the classical Mach-Zehnder interferometer.

  20. Adaptive DFT-based Interferometer Fringe Tracking

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    An automatic interferometer fringe tracking system has been developed, implemented, and tested at the Infrared Optical Telescope Array (IOTA) observatory at Mt. 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 off-line 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.

  1. Data Processing for Atmospheric Phase Interferometers

    NASA Technical Reports Server (NTRS)

    Acosta, Roberto J.; Nessel, James A.; Morabito, David D.

    2009-01-01

    This paper presents a detailed discussion of calibration procedures used to analyze data recorded from a two-element atmospheric phase interferometer (API) deployed at Goldstone, California. In addition, we describe the data products derived from those measurements that can be used for site intercomparison and atmospheric modeling. Simulated data is used to demonstrate the effectiveness of the proposed algorithm and as a means for validating our procedure. A study of the effect of block size filtering is presented to justify our process for isolating atmospheric fluctuation phenomena from other system-induced effects (e.g., satellite motion, thermal drift). A simulated 24 hr interferometer phase data time series is analyzed to illustrate the step-by-step calibration procedure and desired data products.

  2. 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.

  3. Analysis of a free oscillation atom interferometer

    SciTech Connect

    Kafle, Rudra P.; Zozulya, Alex A.; Anderson, Dana Z.

    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.

  4. Automatic null ellipsometry with an interferometer

    SciTech Connect

    Watkins, Lionel R.

    2009-11-10

    A new approach to automatic null ellipsometry is described in which the analyzer of a traditional polarizer compensator sample analyzer (PCSA) null ellipsometer is replaced with a heterodyne Michelson interferometer. One arm of this interferometer is modified such that it produces a fixed, linearly polarized reference beam, irrespective of the input polarization state. This beam is recombined interferometrically with the measurement beam and spatially separated into its p and s polarizations. The relative phase of the resulting temporal fringes is a linear function of the polarizer azimuthal angle P, and thus this component can be driven to its null position without iteration. Once at null, the azimuthal angle of the reflected, linearly polarized light is trivially determined from the relative amplitude of the fringes. Measurements made with this instrument on a native oxide film on a silicon wafer were in excellent agreement with those made with a traditional PCSA null ellipsometer.

  5. Two color far infrared laser interferometer

    SciTech Connect

    Kawahata, K.; Akiyama, T.; Pavlichenko, R.; Tanaka, K.; Tokuzawa, T.; Ito, Y.; Okajima, S.; Nakayama, K.; Wood, K.

    2006-10-15

    Two color interferometer using a short wavelength far infrared laser has been developed for high performance plasmas on large helical device and for future fusion devices such as ITER. High power laser lines simultaneously oscillating at 57.2 and 47.6 {mu}m were achieved in a CO{sub 2}-laser-pumped CH{sub 3}OD laser. By introducing Ge:Ga photoconductive detectors operating at liquid He temperature, we have successfully detected two color beat signals (0.55 and 1.2 MHz) with excellent signal-to-noise ratio ({approx}40 dB). These beat signals were fed into phase comparators for phase measurement after passing through intermediate frequency bandpass filters. Two color far infraned laser interferometer work was successful in the demonstration of mechanical vibration compensation.

  6. Nonlinear synthetic aperture radar imaging using a harmonic radar

    NASA Astrophysics Data System (ADS)

    Gallagher, Kyle A.; Mazzaro, Gregory J.; Ranney, Kenneth I.; Nguyen, Lam H.; Martone, Anthony F.; Sherbondy, Kelly D.; Narayanan, Ram M.

    2015-05-01

    This paper presents synthetic aperture radar (SAR) images of linear and nonlinear targets. Data are collected using a linear/nonlinear step frequency radar. We show that it is indeed possible to produce SAR images using a nonlinear radar. Furthermore, it is shown that the nonlinear radar is able to reduce linear clutter by at least 80 dB compared to a linear radar. The nonlinear SAR images also show the system's ability to detect small electronic devices in the presence of large linear clutter. The system presented here has the ability to completely ignore a 20-inch trihedral corner reflector while detecting a RF mixer with a dipole antenna attached.

  7. 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.

  8. 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.

  9. Large aperture ac interferometer for optical testing.

    PubMed

    Moore, D T; Murray, R; Neves, F B

    1978-12-15

    A 20-cm clear aperture modified Twyman-Green interferometer is described. The system measures phase with an AC technique called phase-lock interferometry while scanning the aperture with a dual galvanometer scanning system. Position information and phase are stored in a minicomputer with disk storage. This information is manipulated with associated software, and the wavefront deformation due to a test component is graphically displayed in perspective and contour on a CRT terminal. PMID:20208642

  10. Matter-wave interferometry: towards antimatter interferometers

    NASA Astrophysics Data System (ADS)

    Sala, Simone; Castelli, Fabrizio; Giammarchi, Marco; Siccardi, Stefano; Olivares, Stefano

    2015-10-01

    Starting from an elementary model and refining it to take into account more realistic effects, we discuss the limitations and advantages of matter-wave interferometry in different configurations. We focus on the possibility to apply this approach to scenarios involving antimatter, such as positrons and positronium atoms. In particular, we investigate the Talbot-Lau interferometer with material gratings and discuss in details the results in view of the possible experimental verification.

  11. Binaries for the Stellar Interferometer Program

    NASA Astrophysics Data System (ADS)

    Kelz, A.

    Interferometry combined with spectroscopy and spectrophotometry yields almost all stellar parameters for binary systems. The Sydney University Stellar Interferometer (SUSI) together with the Sydney University Spectrograph (SUSPECT) will be able to measure these fundamental properties. For interferometrically resolved double-lined spectroscopic binaries this method will allow an independent determination of the distance to these systems and will make acontribution to the mass-luminosity relationship.

  12. ALISEO: a new stationary imaging interferometer

    NASA Astrophysics Data System (ADS)

    Barducci, Alessandro; De Cosmo, Vittorio; Marcoionni, Paolo; Pippi, Ivan

    2004-10-01

    ALISEO (Aerospace Leap-frog Imaging Static Interferometer for Earth Observation) is a prototype of a new imaging interferometer for Earth Observation from the Space. This instrument has been derived from the so called "static interferometers", which do not employ any moving part to optically scan the instrument field-of-view. The device acquires the image of an object with superimposed a pattern of autocorrelation functions of the electromagnetic field coming from each pixel. The complete interferogram, constituted by a system of vertical fringes, is retrieved by moving the observed target with respect to the imaging device. The dependence of the OPD on the radiation-source spectral content, has been addressed performing a set of measurements by spectrally pre-filtering a 600W halogen lamp by means of interference filters with bandwidth of 10nm. We also describe the procedure of pre-elaboration of the acquired data to retrieve the spectrum of at-sensor radiance (dark signal subtraction, spectral instrument response compensation, effects of vignetting and Fourier transform algorithm). Laboratory measurements obtained by ALISEO are presented and discussed. This instrument was partially developed under a contract of Agenzia Spaziale Italiana (ASI).

  13. Fiber Fizeau interferometer for remote passive sensing

    NASA Astrophysics Data System (ADS)

    Bush, Jeff; Suh, Kwang

    2012-06-01

    Fizeau sensors constitute a large proportion of the fiber optic interferometric type sensors in use today. These include EFPI, FFPI, certain MEMS devices and in-line fiber intrinsic dual-reflector type sensors. The vast majority of the published literature covering these sensor types models them with a "2-beam" interferometer approximation, and implement interrogation approaches considering the same. Analysis performed and results presented show that the 2-beam model is not sufficient when reflection coefficients exceed 1% and traditional quadrature interrogation can result in linearity or distortion errors roughly in directly proportion to the reflectivity coefficients of the Fizeau sensor. A 4-beam multi-path interferometer model is developed and exercised to demonstrate this problem. Further this model shows that the "errors" in comparison to an ideal 2-beam interferometer model are symmetric across the unit circle and suggests that linear interrogation may be accomplished if orthonormal sample sets over the entire unit circle are used to replace the traditional (simple) quadrature sampling. This is shown to be true in both modeling and lab evaluations. The resulting approach has capabilities of remote, passive sensor operation, high frequency response, large, linear dynamic range and low noise. The interrogation technique demonstrated involves a phase generated carrier with full fringe sampling and quadrature determination which cancels the errors experienced from simple quadrature determination. Such an improvement enables higher reflectivity, higher SNR, high-fidelity fiber Fizeau sensor designs. Applications include embedded sensors, line sensors, or mechanically adapted for acoustic, pressure, vibration, acceleration or seismic sensing.

  14. MIKES’ primary phase stepping gauge block interferometer

    NASA Astrophysics Data System (ADS)

    Byman, V.; Lassila, A.

    2015-08-01

    MIKES’ modernized phase stepping interferometer for gauge block calibration (PSIGB) will be described. The instrument is based on the well-regarded NPL-TESA gauge block interferometer from 1994. The decision to upgrade the instrument resulted from several components, such as the PC and charge-coupled device (CCD) camera, having reached the end of their lifetime. In this paper modernized components, measurement method and analysis will be explained. The lasers are coupled to the instrument using single mode fiber. The instrument uses phase stepping generated by an added optical window on a controllable rotatory table in the reference arm with a recently developed nine-position phase stepping algorithm. Unwrapping is done with a robust path following algorithm. Procedures for adjusting the interferometer are explained. Determination and elimination of wavefront error, coherent noise and analysis of their influence on the results is described. Flatness and variation in length are also important parameters of gauge blocks to be characterized, and the corresponding analysis method is clarified. Uncertainty analysis for the central length, flatness and variation in length is also described. The results are compared against those of the old hardware and software. The standard uncertainty for central length measurement is u = [(9.5?nm)2 + (121 × 10-9?L)2]½, where L is measured length.

  15. Subaperture stitching interferometer for large optics

    NASA Astrophysics Data System (ADS)

    Zeng, Shengyue; Dai, Yifan; Chen, Shanyong

    2009-05-01

    Ultra-high precision measurement of the form is critical in deterministic machining of optical components. It is generally accomplished with an interferometer. However, a standard interferometer is incompetent for large convex aspherical surfaces or those with large relative apertures. Hence subaperture stitching interferometry was proposed to extend the vertical range of measurement and enhance the lateral resolution, based on the idea of "stitching pieces together". This paper presents a prototype design for subaperture stitching interferometer (SASI) for large optics. It applies to large flats (clear aperture<700mm), large concave spherical or aspherical surfaces (clear aperture<350mm, 1:2

  16. Model-based phase-shifting interferometer

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    A model-based phase-shifting interferometer (MPI) is developed, in which a novel calculation technique is proposed instead of the traditional complicated system structure, to achieve versatile, high precision and quantitative surface tests. In the MPI, the partial null lens (PNL) is employed to implement the non-null test. With some alternative PNLs, similar as the transmission spheres in ZYGO interferometers, the MPI provides a flexible test for general spherical and aspherical surfaces. Based on modern computer modeling technique, a reverse iterative optimizing construction (ROR) method is employed for the retrace error correction of non-null test, as well as figure error reconstruction. A self-compiled ray-tracing program is set up for the accurate system modeling and reverse ray tracing. The surface figure error then can be easily extracted from the wavefront data in forms of Zernike polynomials by the ROR method. Experiments of the spherical and aspherical tests are presented to validate the flexibility and accuracy. The test results are compared with those of Zygo interferometer (null tests), which demonstrates the high accuracy of the MPI. With such accuracy and flexibility, the MPI would possess large potential in modern optical shop testing.

  17. Fizeau interferometer for global astrometry in space.

    PubMed

    Loreggia, Davide; Gardiol, Daniele; Gai, Mario; Lattanzi, Mario G; Busonero, Deborah

    2004-02-01

    We discuss the design and the performance of a Fizeau interferometer with a long focal length and a large field of view that is well suited for a global astrometry space mission. Our work focuses on the geometric optimization and minimization of aberration of such an astrometric interferometer, which is able to observe astronomical targets down to the visual magnitude (mag) mv = 20 mag, with an accuracy in the measurements of 10 micro-arcseconds at mv = 15 mag. We assume a mission profile similar to that of the Global Astrometric Interferometer for Astrophysics mission of the European Space Agency. In this framework, data acquisition is performed by an array of CCDs working in time-delay integration mode. Optical aberrations, particularly distortion and coma, play a crucial role in the efficiency of this technique. We present a design solution that meets the requirements for the best possible exploitation of the time-delay integration mode over a field of view of 0.7 degrees x 0.7 degrees. PMID:14960061

  18. 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.

  19. A Study of Imaging Interferometer Simulators

    NASA Technical Reports Server (NTRS)

    Allen, Ronald J.

    2002-01-01

    Several new space science mission concepts under development at NASA-GSFC for astronomy are intended to carry out synthetic imaging using Michelson interferometers or direct (Fizeau) imaging with sparse apertures. Examples of these mission concepts include the Stellar Imager (SI), the Space Infrared Interferometric Telescope (SPIRIT), the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS), and the Fourier-Kelvin Stellar Interferometer (FKSI). We have been developing computer-based simulators for these missions. These simulators are aimed at providing a quantitative evaluation of the imaging capabilities of the mission by modelling the performance on different realistic targets in terms of sensitivity, angular resolution, and dynamic range. Both Fizeau and Michelson modes of operation can be considered. Our work is based on adapting a computer simulator called imSIM, which was initially written for the Space Interferometer Mission in order to simulate the imaging mode of new missions such as those listed. In a recent GSFC-funded study we have successfully written a preliminary version of a simulator SISIM for the Stellar Imager and carried out some preliminary studies with it. In a separately funded study we have also been applying these methods to SPECS/SPIRIT.

  20. Venus Radar Mapper (VRM): Multimode radar system design

    NASA Technical Reports Server (NTRS)

    Johnson, William T. K.; Edgerton, Alvin T.

    1986-01-01

    The surface of Venus has remained a relative mystery because of the very dense atmosphere that is opaque to visible radiation and, thus, normal photographic techniques used to explore the other terrestrial objects in the solar system are useless. The atmosphere is, however, almost transparent to radar waves and images of the surface have been produced via Earth-based and orbital radars. The technique of obtaining radar images of a surface is variously called side looking radar, imaging radar, or synthetic aperture radar (SAR). The radar requires a moving platform in which the antenna is side looking. High resolution is obtained in the cross-track or range direction by conventional radar pulse encoding. In the along-track or azimuth direction, the resolution would normally be the antenna beam width, but for the SAR case, a much longer antenna (or much sharper beam) is obtained by moving past a surface target as shown, and then combining the echoes from many pulses, by using the Doppler data, to obtain the images. The radar design of the Venus Radar Mapper (VRM) is discussed. It will acquire global radar imagery and altimetry data of the surface of Venus.

  1. Radar investigation of asteroids

    NASA Technical Reports Server (NTRS)

    Ostro, S. J.

    1986-01-01

    The number of radar detected asteroids has climbed from 6 to 40 (27 mainbelt plus 13 near-Earth). The dual-circular-polarization radar sample now comprises more than 1% of the numbered asteroids. Radar results for mainbelt asteroids furnish the first available information on the nature of these objects at macroscopic scales. At least one object (2 Pallas) and probably many others are extraordinarily smooth at centimeter-to-meter scales but are extremely rough at some scale between several meters and many kilometers. Pallas has essentially no small-scale structure within the uppermost several meters of the regolith, but the rms slope of this regolith exceeds 20 deg., much larger than typical lunar values (approx. 7 deg.). The origin of these slopes could be the hypervelocity impact cratering process, whose manifestations are likely to be different on low-gravity, low-radius-of-curvature objects from those on the terrestrial planets. The range of mainbelt asteroid radar albedoes is very broad and implies big variations in regolith porosity or metal concentration, or both. The highest albedo estimate, for 16 Psyche, is consistent with a surface having porosities typical of lunar soil and a composition nearly completely metallic. Therefore, Psyche might be the collisionally stripped core of a differentiated small plant, and might resemble mineralogically the parent bodies of iron meteorites.

  2. Radar investigation of asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1986-09-01

    The number of radar detected asteroids has climbed from 6 to 40 (27 mainbelt plus 13 near-Earth). The dual-circular-polarization radar sample now comprises more than 1% of the numbered asteroids. Radar results for mainbelt asteroids furnish the first available information on the nature of these objects at macroscopic scales. At least one object (2 Pallas) and probably many others are extraordinarily smooth at centimeter-to-meter scales but are extremely rough at some scale between several meters and many kilometers. Pallas has essentially no small-scale structure within the uppermost several meters of the regolith, but the rms slope of this regolith exceeds 20 deg., much larger than typical lunar values (approx. 7 deg.). The origin of these slopes could be the hypervelocity impact cratering process, whose manifestations are likely to be different on low-gravity, low-radius-of-curvature objects from those on the terrestrial planets. The range of mainbelt asteroid radar albedoes is very broad and implies big variations in regolith porosity or metal concentration, or both. The highest albedo estimate, for 16 Psyche, is consistent with a surface having porosities typical of lunar soil and a composition nearly completely metallic. Therefore, Psyche might be the collisionally stripped core of a differentiated small plant, and might resemble mineralogically the parent bodies of iron meteorites.

  3. Mars Radar Catalog

    NASA Technical Reports Server (NTRS)

    Simpson, R. A.; Tyler, G. L.

    1985-01-01

    Radar observations of Mars have been conducted since 1963 using four Earth based facilities. Wavelengths have ranged from about 3 to about 70 cm. Experiments have been conducted in ranging, spectral, and mixed modes. Results include topographic profiles, estimates of dielectric constant and meter scale surface roughness, and qualtitative determinations of centimeter scale structure.

  4. Synthetic Aperture Radar Interferometry

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  5. Impulse radar studfinder

    DOEpatents

    McEwan, Thomas E.

    1995-01-01

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes.

  6. Impulse radar studfinder

    DOEpatents

    McEwan, T.E.

    1995-10-10

    An impulse radar studfinder propagates electromagnetic pulses and detects reflected pulses from a fixed range. Unmodulated pulses, about 200 ps wide, are emitted. A large number of reflected pulses are sampled and averaged. Background reflections are subtracted. Reflections from wall studs or other hidden objects are detected and displayed using light emitting diodes. 9 figs.

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

    SciTech Connect

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

    2010-05-28

    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 K{sub u} 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.

  8. The University of Florida LISA interferometer simulator

    NASA Astrophysics Data System (ADS)

    Mueller, Guido; Hochman, Steven; Mitryk, Shawn; Sanjuan Munoz, Jose; Preston, Alix; Sweeney, Dylan; Yu, Yinan; Tanner, David B.; Mueller, Guido

    Interferometric gravitational wave detectors such as LISA are built around two major subsys-tems. Gravitational reference sensors (GRS) consist of several freely-falling proof masses which follow variations in space time caused by passing gravitational waves. Spurious accelerations of the proof masses caused by technical or environmental forces have to be below the fN/rtHz level in the frequency band of interest. Interferometer measurement systems (IMS) measure the changes in the distances between the proof masses with sufficient sensitivity. The GRS-system for LISA has been developed over the last ten years and will be tested in a dedicated test mission, the LISA Test Package (LTP), scheduled for launch in 2012. The IMS of LISA is one of the most dynamic and longest interferometers ever envisioned. It consists of many subsystems which depend on the long light-travel times, the changes in the light-travel times and the induced Doppler shifts. The signals of the IMS are beat tones taken between vari-ous lasers at various locations on the three spacecraft. The phase evolution of each signal is measured against on-board clocks, after which linear combinations between appropriately time-shifted signals are formed to cancel about 10 orders of magnitude of laser frequency noise and thereby reach LISA sensitivity. Achieving 10 orders of magnitude of common mode rejection is already a daunting task for a small static interferometer in an optical laboratory. LISA is a very large and highly dynamic interferometer with constantly changing arms which for exam-ple requires to adapt permanently the noise cancelling linear combinations to the current arm lengths and spacecraft velocities while continuously monitoring the relative noise between the three independent on-board clocks. The University of Florida LISA Interferometer Simulator (UFLIS) is a hardware-in-the-loop simulator which includes multiple lasers, LISA-like signal travel-times and LISA-like Doppler shifts. UFLIS generates signals that currently are the most LISA-like signals in the world; these can be used to develop, test, and verify various techniques and algorithms proposed to achieve the required LISA performance. In this presentation I will discuss the core elements of UFLIS and how these elements are used to generate LISA-like signals. I will present results from tests we have performed and discuss our future test plans. This work is supported by NASA grants NNX08AG75G and NNX09AF99G

  9. Reflective grating interferometer: a folded reversal and shearing wave-front interferometer.

    PubMed

    Ferraro, Pietro; De, Nicola Sergio; Finizio, Andrea; Pierattini, Giovanni

    2002-01-10

    The reflecting grating interferometer (RGI) is a folded and reversal wave-front interferometer sensitive only to asymmetrical aberrations such as third-order coma. The RGI can isolate and evaluate coma both in nearly collimated and in noncollimated beams. We propose a RGI with a different optical configuration that includes a lateral shearing in addition to folding and reversal operations. With lateral shear, the RGI also becomes sensitive to other terms of third-order aberrations such as defocusing, astigmatism, and spherical aberration. Optical path difference equations for interpreting interferograms and numerical simulations are presented to show how the interferometer works in the shearing configuration. Its potential applications are described and discussed. PMID:11899273

  10. Multiple interferometer interaction free measurement using polarized light

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Pitt, Kevin; Milgie, Michael

    2016-02-01

    This paper experimentally and theoretically investigates improving interaction free measurement (IFM) efficiency using a chain of multiple interferometers with transmissive beam splitters of reflectivity less than 50%. The object measured with IFM is present or absent from one of the interferometer paths depending on the polarization of the incident light. The ability to effectively move an object in and out of the system without physically moving it makes implementing a multiple chain interferometer more practical. It also allows verifying the desired interferometer phase while simultaneously making the IFM measurement. A recursive phase model of a chain of interferometers is presented which accounts for both losses and arbitrary phase differences between each pair of arms in the chain. The recursive model predicts the photodiode power and is experimentally validated for a chain of interferometers of lengths one and two.

  11. 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.

  12. 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

  13. 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

  14. 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.

  15. Terrestrial Planet Finder Interferometer: 2007-2008 Progress and Plans

    NASA Technical Reports Server (NTRS)

    Lawson, P. R.; Lay, O. P.; Martin, S. R.; Peters, R. D.; Gappinger, R. O.; Ksendzov, A.; Scharf, D. P.; Booth, A. J.; Beichman, C. A.; Serabyn, E.; Johnston, K. J.; Danchi, W. C.

    2008-01-01

    This paper provides an overview of technology development for the Terrestrial Planet Finder Interferometer (TPF-I). TPF-I is a mid-infrared space interferometer being designed with the capability of detecting Earth-like planets in the habitable zones around nearby stars. The overall technology roadmap is presented and progress with each of the testbeds is summarized. The current interferometer architecture, design trades, and the viability of possible reduced-scope mission concepts are also presented.

  16. Gravitational Wave Detection with Single-Laser Atom Interferometers

    NASA Technical Reports Server (NTRS)

    Yu, Nan; Tinto, Massimo

    2011-01-01

    A new design for a broadband detector of gravitational radiation relies on two atom interferometers separated by a distance L. In this scheme, only one arm and one laser are used for operating the two atom interferometers. The innovation here involves the fact that the atoms in the atom interferometers are not only considered as perfect test masses, but also as highly stable clocks. Atomic coherence is intrinsically stable, and can be many orders of magnitude more stable than a laser.

  17. Modeling Fizeau interferometer based on ray tracing with Zemax

    NASA Astrophysics Data System (ADS)

    He, Yiwei; Hou, Xi; Wu, Yongqian; Wu, Fan; Quan, Haiyang; Liu, Fengwei

    2015-10-01

    A convenient method to study the influence of error sources in Fizeau is to build a ray-tracing model to simulate the error sources. In this paper an interferometer model is presented; an extension program is called to simulate the interference; and a preliminary research of several error sources is conducted. These examples demonstrate error analysis based on interferometer models is feasible and provide some guidance for optimizing our interferometer design.

  18. 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.

  19. 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.

  20. 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.

  1. A neural network approach to correcting nonlinearity in optical interferometers

    NASA Astrophysics Data System (ADS)

    Li, Zhi; Herrmann, Konrad; Pohlenz, Frank

    2003-03-01

    Real interferometers with phase quadrature detecting subsystems usually demonstrate nonlinearity with length measurements. Conventional nonlinearity correction techniques based on elliptical fittings are reviewed and their limitation is investigated using computer simulations. A new approach based on neural networks (NNs) for correcting nonlinearity in optical interferometers for length and displacement measurements is introduced, the principle of which is given (including the architecture of the NN) and its training method. An experimental setup was developed based on a differential plane-mirror interferometer for testing the proposed method. The experimental results show that this new approach is successfully applicable to real, noisy interferometer signals.

  2. 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-

  3. Kuiper Belt Mapping Radar

    NASA Technical Reports Server (NTRS)

    Freeman, A.; Nilsen, E.

    2001-01-01

    Since their initial discovery in 1992, to date only a relatively small number of Kuiper Belt Objects (KBO's) have been discovered. Current detection techniques rely on frame-to-frame comparisons of images collected by optical telescopes such as Hubble, to detect KBO's as they move against the background stellar field. Another technique involving studies of KBO's through occultation of known stars has been proposed. Such techniques are serendipitous, not systematic, and may lead to an inadequate understanding of the size, range, and distribution of KBO's. In this paper, a future Kuiper Belt Mapping Radar is proposed as a solution to the problem of mapping the size distribution, extent, and range of KBO's. This approach can also be used to recover radar albedo and object rotation rates. Additional information is contained in the original extended abstract.

  4. 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.

  5. 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.

  6. RADAR Reveals Titan Topography

    NASA Technical Reports Server (NTRS)

    Kirk, R. L.; Callahan, P.; Seu, R.; Lorenz, R. D.; Paganelli, F.; Lopes, R.; Elachi, C.

    2005-01-01

    The Cassini Titan RADAR Mapper is a K(sub u)-band (13.78 GHz, lambda = 2.17 cm) linear polarized RADAR instrument capable of operating in synthetic aperture (SAR), scatterometer, altimeter and radiometer modes. During the first targeted flyby of Titan on 26 October, 2004 (referred to as Ta) observations were made in all modes. Evidence for topographic relief based on the Ta altimetry and SAR data are presented here. Additional SAR and altimetry observations are planned for the T3 encounter on 15 February, 2005, but have not been carried out at this writing. Results from the T3 encounter relevant to topography will be included in our presentation. Data obtained in the Ta encounter include a SAR image swath

  7. Radar cross-sectional study using noise radar

    NASA Astrophysics Data System (ADS)

    Freundorfer, A. P.; Siddiqui, J. Y.; Antar, Y. M. M.

    2015-05-01

    A noise radar system is proposed with capabilities to measure and acquire the radar cross-section (RCS) of targets. The proposed system can cover a noise bandwidth of near DC to 50 GHz. The noise radar RCS measurements were conducted for selective targets like spheres and carpenter squares with and without dielectric bodies for a noise band of 400MHz-5000MHz. The bandwidth of operation was limited by the multiplier and the antennae used.

  8. 51. View of upper radar scanner switch in radar scanner ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. View of upper radar scanner switch in radar scanner building 105 from upper catwalk level showing emanating waveguides from upper switch (upper one-fourth of photograph) and emanating waveguides from lower radar scanner switch in vertical runs. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  9. 41. Perimeter acquisition radar building radar element and coaxial display, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    41. Perimeter acquisition radar building radar element and coaxial display, with drawing of typical antenna section. Drawing, from left to right, shows element, aluminum ground plane, cable connectors and hardware, cable, and back-up ring. Grey area is the concrete wall - Stanley R. Mickelsen Safeguard Complex, Perimeter Acquisition Radar Building, Limited Access Area, between Limited Access Patrol Road & Service Road A, Nekoma, Cavalier County, ND

  10. Modified Phasemeter for a Heterodyne Laser Interferometer

    NASA Technical Reports Server (NTRS)

    Loya, Frank M.

    2010-01-01

    Modifications have been made in the design of instruments of the type described in "Digital Averaging Phasemeter for Heterodyne Interferometry". A phasemeter of this type measures the difference between the phases of the unknown and reference heterodyne signals in a heterodyne laser interferometer. The phasemeter design lacked immunity to drift of the heterodyne frequency, was bandwidth-limited by computer bus architectures then in use, and was resolution-limited by the nature of field-programmable gate arrays (FPGAs) then available. The modifications have overcome these limitations and have afforded additional improvements in accuracy, speed, and modularity. The modifications are summarized.

  11. Mach-Zehnder interferometer for movement monitoring

    NASA Astrophysics Data System (ADS)

    Vasinek, Vladimir; Cubik, Jakub; Kepak, Stanislav; Doricak, Jan; Latal, Jan; Koudelka, Petr

    2012-06-01

    Fiber optical interferometers belong to highly sensitive equipments that are able to measure slight changes like distortion of shape, temperature and electric field variation and etc. Their great advantage is that they are insensitive on ageing component, from which they are composed of. It is in virtue of herewith, that there are evaluated no changes in optical signal intensity but number interference fringes. To monitor the movement of persons, eventually to analyze the changes in state of motion we developed method based on analysis the dynamic changes in interferometric pattern. We have used Mach- Zehnder interferometer with conventional SM fibers excited with the DFB laser at wavelength of 1550 nm. It was terminated with optical receiver containing InGaAs PIN photodiode. Its output was brought into measuring card module that performs on FFT of the received interferometer signal. The signal rises with the composition of two waves passing through single interferometer arm. The optical fiber SMF 28e in one arm is referential; the second one is positioned on measuring slab at dimensions of 1x2m. A movement of persons around the slab was monitored, signal processed with FFT and frequency spectra were evaluated. They rose owing to dynamic changes of interferometric pattern. The results reflect that the individual subjects passing through slab embody characteristic frequency spectra, which are individual for particular persons. The scope of measuring frequencies proceeded from zero to 10 kHz. It was also displayed in experiments that the experimental subjects, who walked around the slab and at the same time they have had changed their state of motion (knee joint fixation), embodied characteristic changes in their frequency spectra. At experiments the stability of interferometric patterns was evaluated as from time aspects, so from the view of repeated identical experiments. Two kinds of balls (tennis and ping-pong) were used to plot the repeatability measurements and the gained spectra at repeated drops of balls were compared. Those stroked upon the same place and from the same elevation and dispersion of the obtained frequency spectra was evaluated. These experiments were performed on the series of 20 repeated drops from highs of 0,5 and 1m. The evaluation of experiments displayed that the dispersion of measured values is lower than 4%. Frequency response has been verified with the loudspeaker connected to signal generator and amplifier. Various slabs have been measured and frequency ranges were compared for particular slab designs.

  12. DASI: The Degree Angular Scale Interferometer

    NASA Astrophysics Data System (ADS)

    Leitch, E. M.; Carlstrom, J. E.; Davidson, G.; Dragovan, M.; Halverson, N. W.; Holzapfel, W. L.; Laroque, S.; Kovac, J.; Pryke, C.; Schartman, E.; Yamasaki, M. J.

    The Degree Angular Scale Interferometer (DASI) is a 13-element array of horns operating at 26 - 36 GHz designed explicitly to image anisotropy in the Cosmic Microwave Background radiation and to determine its angular power spectrum over the range 140 < l < 920. DASI was deployed sucessfully at the Amudsen-Scott South Pole station last austral summer (1999/2000) and is now collecting data. An overview of the instrument and its capabilities, as well as the current state of the observations and data analysis will be presented.

  13. In-fiber Michelson interferometer inclinometer

    NASA Astrophysics Data System (ADS)

    da Silveira, C. R.; Jorge, P. A. S.; Costa, J. W. A.; Giraldi, M. T. M. R.; Santos, J. L.; Frazão, O.

    2015-09-01

    This work describes an in-fiber Michelson interferometer inclinometer which is sensitive to curvature applied in the tapered region. The performance of this inclinometer is evaluated by calculating the variation of the fringe visibility near the 1550 nm spectral range as a function of the tilt angle. It is presented the results of four experimental measurements and calculated the average and standard deviation of those measurements. The results indicate a good response of the sensor within the angular range between 3° and 6°. The average of those four measurements is around -0.15/° and the greatest standard deviation is about 5.5%.

  14. Macroscopic coherent rectification in Andreev interferometers.

    PubMed

    Meair, Jonathan; Jacquod, Philippe

    2012-07-11

    We investigate nonlinear transport through quantum coherent metallic conductors contacted to superconducting components. We find that in certain geometries, the presence of superconductivity generates a large, finite-average rectification effect. Specializing to Andreev interferometers, we show that the direction and magnitude of rectification can be controlled by a magnetic flux tuning the superconducting phase difference at two contacts. In particular, this results in the breakdown of an Onsager reciprocity relation at finite bias. The rectification current is macroscopic in that it scales with the linear conductance, and we find that it exceeds 5% of the linear current at sub-gap biases of a few tens of microelectronvolts. PMID:22713687

  15. 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.

  16. Controller of the Laser Interferometer Space Antenna

    NASA Technical Reports Server (NTRS)

    Hyde, T. T.; Maghami, P. G.; Kim, J.

    2004-01-01

    The Laser Interferometer Space Antenna mission is a planned gravitational wave detector consisting of three spacecraft in heliocentric orbit. Laser interferometry is used to measure distance fluctuations between test masses aboard each spacecraft to the picometer level over a 5 million kilometer separation. The Disturbance Reduction System comprises the pointing and positioning control of the spacecraft, electrostatic suspension control of the test masses, and point-ahead and acquisition control. This paper presents a control architecture and design for the Disturbance Reduction System to meet the stringent pointing and positioning requirements. Simulations are performed to demonstrate the feasibility of the proposed architecture.

  17. Modeling the Laser Interferometer Space Antenna Optics

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Pedersen, Trace R.; McNamara, Paul

    2005-01-01

    Creating an optical model of the Laser Interferometer Space antenna which can be used to predict optical sensitivities and set tolerances sufficiently well such that picometer level displacements can be reliably seen poses certain challenges. In part, because the distances between key optical elements, the proof masses, are constantly changing, at speeds of meters/second, the separation between them is about 5 million kilometers and a contributing factor to optical jitter is the self-gravity of the spacecraft. A discussion of the current state and future approach(s) to the creation of such an optical model will be presented.

  18. Data Flow System for the VLT Interferometer

    NASA Astrophysics Data System (ADS)

    Ballester, P.; Licha, T.; Percheron, I.; Sabet, C.

    2006-07-01

    A milestone on the accuracy of angular measurements is reached with each new instrument on the VLT interferometer: about 10 milliarcsec for MIDI (N Band), 1 milliarcsec for AMBER (JHK bands) and, later, the ultimate goal of 10 microarcsec for the PRIMA imaging and astrometry facility. Extracting the science information from these measurements requires a unified understanding of the data obtained by modelling, homogeneous calibration of large datasets and robust data reduction methods. We describe in this poster the operational tools provided for observation preparation, pipeline processing, and data quality control.

  19. Goldstone solar system radar

    NASA Technical Reports Server (NTRS)

    Jurgens, Raymond F.

    1991-01-01

    Caltech/Jet Propulsion Laboratory (JPL) radar astronomers made use of the Very Large Array (VLA) at Socorro, NM, during February 1990, to receive radio echoes from the planet Venus. The transmitter was the 70 meter antenna at the Goldstone complex northwest of Barstow, CA. These observations contain new information about the roughness of Venus at cm to decimeter scales and are complementary to information being obtained by the Magellan spacecraft. Asteroid observations are also discussed.

  20. Radar detection of Iapetus

    NASA Astrophysics Data System (ADS)

    Black, G. J.; Campbell, D. B.; Carter, L. M.; Ostro, S. J.

    2002-09-01

    We have obtained echoes from the bright, trailing hemisphere of Iapetus using the Arecibo Observatory's 13-cm radar system on three dates in January 2002. A circularly polarized signal was transmitted and an echo in the opposite circular (OC) sense to that transmitted was clearly received along with a much weaker detection of echo power in the same circular (SC) sense. Prior to this experiment, one expectation may have been that the radar scattering properties of Iapetus may behave like the similar atmosphere-less, icy surfaces of the Galilean satellites which, due to an efficient multiple scattering mechanism, are strong backscatterers with SC reflections stronger than their OC reflections. Instead we find that Iapetus' radar cross section and polarization properties are very different from those of the icy Galilean satellites, and more reminiscent of less efficient and less exotic scattering mechanisms such as dominate the echoes from inner Solar System targets. Thus these observations indicate that there is a significant difference between the surface properties of Iapetus and the icy Galileans despite their overall classification as low temperature, water ice surfaces. A plausible explanation for Iapetus' inefficient scattering is that contaminants in the water ice increase the absorption of the signal and suppress any multiple scattering. Likely contaminants on Iapetus are ammonia and the dark material from Cassini Regio embedded below the surface. Proposed observations will seek to measure Iapetus' radar scattering law and to detect the dark, leading side which was not targeted during this observing session. The Arecibo Observatory is part of the National Astronomy and Ionosphere Center, which is operated by Cornell University under a cooperative agreement with the National Science Foundation.

  1. Imaging synthetic aperture radar

    DOEpatents

    Burns, Bryan L.; Cordaro, J. Thomas

    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.

  2. A stellar interferometer on the Moon

    NASA Astrophysics Data System (ADS)

    Porro, Irene

    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 has been developed. As a guide for the reader here I describe the content of each chapter, which represents the original contribution (except when it is specifically declared) to the research accomplished. This section consists in the Introduction itself, with a presentation of the motivations for this research work, and in the chapter Interferometry from the Earth and from the Moon. The first part of this chapter shows the performances which are expected to be reached by ground-based interferometers (Colavita, 1992) by using adaptive optics systems (Beckers, 1993). The evaluation is made separately for the case of high resolution imaging and for high accuracy astrometric measurements. The most optimistic results expected for ground-based instruments determine the level of the performance that has to be required from a space interferometer (both an orbiting and a lunar instrument). In the second part of the chapter I specifically deal with the case of a lunar interferometer, which allows to put together the advantages o ered by a ground-based instrument (very long baseline, a stable platform) and those offered by the space environment (absence of atmospheric turbulence, long integration times, and wavelength range of observation from the ultraviolet to the far infrared). In order to evaluate the limits of the lunar interferometer, I need to consider three subjects with which I did not explicitly dealt for the study on IOTA: the maximum length of the baseline (Tango and Twiss, 1974), the maximum integration time, and the performances obtainable at the minimum temperature of operation (Ridgway, 1990). The chapter ends with a list of the main reviews which deal with the scientific objectives of space and lunar interferometry. In Appendix A I present an introduction to the principles of optical stellar interferometry. This part is mainly derived by the study and re-elaboration of the contents of the following works: Armstrong et al. (1995), Shao and Colavita (1992), and Born and Wolf (1980). In this section I present the work I specifically developed within the IOTA project. This work allowed me to, directly or indirectly, acquire the theoretical and technical knowledge I then applied in the study on the lunar interferometer. After having identified some of the main sources of systematic error for an interferometer, I examined: the problem of the telescope alignment, the beamsplitter behaviour, the effects that thermal variations cause on the optics and their support structures. The results obtained in these analyses and the evaluations performed on the performances of other subsystems of the instrument, allowed me to proceed in the evaluation of the instrumental visibility loss for IOTA. In the first chapter (I) I present a general description of the IOTA instrument, avoiding a detailed description of each subsystem. When it is necessary, this is given in its appropriate context. The second chapter (II) is the result of the largest part of my work done on IOTA: the analisys of the alignment of each telescope of the interferometer. A non-perfect alignment of the telescope optics causes a distortion of the wavefront coming from the observed object. The distortions affecting the wavefront are responsible for the corruption of the interference fringes produced by the instrument, and eventually of the astrophysics information derived from their analysis. In order to study the effect of the optics misalignment on the performances of IOTA, I wrote a program to simulate some misalignment conditions and to evaluate the wavefront aberration they cause. For each case considered, an interferogram is produced by simulating the interference of the distorted wavefront with a plane wavefront. This interferogram is a means to represent the loss in the optical performance of the system. The interferograms produced by the simulation program are collected in an "atlas" (I present an extract of it as an independent appendix of this thesis) which will be used during the telescope alignment operation to help in diagnosing the error in the optics position. The initial part of the chapter is devoted to a brief introduction to the wavefront aberration theory (from Schroeder, 1987) and to the analysis of one of the IOTA telescopes when it is in auto-collimation mode (the configuration used for the alignment operation). On the basis of this analysis I derived the misalignment conditions which I studied by means of the simulation program. The third chapter (III) is devoted to the beamsplitter, a fundamental element for most Michelson optical stellar interferometers. The beamsplitter is the optical element by means of which the beams are made interfere. In the first part of the chapter I describe the characteristics of a beamsplitter for astronomical applications. This description is mainly based on a study that James D. Phillips accomplished within the project of the space interferometer POINTS. To my knowledge, this is the only study which deals with both the theoretical approach of the problem and the experimental aspect involved in the design of a beamsplitter for astronomical applications. In the second part of the chapter I present the original contribution on this subject, which consists in the analysis of the polarizations effects introduced by the beamsplitter. In particular I obtain the expression of the fringe intensity when considering the polarization effects. This expression contains a term which gives the visibility loss due to the phase difference between the polarization components of the interfering beams. Then I evaluate the loss in visibility for IOTA and present the results of the simulation of the interfering fringes obtained when polarization effects are present. In the fourth chapter (IV) I deal with the problem of how thermal e ects a ect the performance of a stellar interferometer. Knowing these effects and the thermal characteristic of the site when designing the instrument, allows to riduce its sensibility to the thermal changes. In the first part of the chapter I take into consideration the optical components, both reffective and refractive, of the system: I evaluate the wavefront error due to the alteration of the physical characteristics of the optical material as a consequence of a temperature variation. In the second part I consider the effects on the structure which supports and connects the primary and the secondary mirrors: a temperature variation may cause a perturbation in the telescope alignment and hence a wavefront error. The general expressions for the wavefront error obtained in the rst and second part are then applied to IOTA. In particular the result of this study are used to perform an a posteriori evaluation of the visibility loss for IOTA. Finally, I performed a detailed analysis for the evaluation of the wavefront error introduced by a non-perfect thermal compensation affecting the metric structure which connects the mirrors of the telescope. The fifth chapter (V) consists in a description of the causes of mechanical instability which can a effect the operation of IOTA. In most cases I only present a qualitative description of the phenomena and a rough evaluation of their effects. This is because an accurate evaluation of the wavefront error induced by each of them requires a specialistic study of the vibration propagation throughout the whole structure of the interferometer, a study which is beyond the purposes of this work. I performed a more detailed evaluation only to determine the efficiency of the insolation system applied to the vacuum pumps. One of the problems arisen the first times the instrument was used for observation in the visible was that of the vibrations introduced by the vacuum pump system. Because of them, it was often impossible to detect the interferometric fringes even if the overall conditions for observation were good. In the sixth chapter (VI) I deal with the evaluation of the wavefront error due to the deformation of the primary mirror caused by the gravitational load. In the seventh chapter (VII) I eventually use the results presented in the previous chapters to evaluate the instrumental visibility of IOTA. A means to evaluate the efficiency of an interferometer is by determining the fringe visibility loss due to the intrinsic characteristics of the instrument. In fact, the smaller is the fringe visibility the more difficult is to extract from it accurate information about the observed object. In the introduction of this chapter I describe the relation, which has ben derived by ten Brummelar et al.(1994), between the Strehl ratio (a quantity which defines the performance of an optical system by means of the wavefront error due to the system itself) and the factor which relates the actual visibility of the object and the visibility measured by the instrument. The rest of the chapter is devoted to the calculation, based on the wavefront error estimations made previously, of the visibility loss related to different subsystems of IOTA. In addition, I evaluated the visibility loss due to di raction e ects on the transmitted beams and to the residual error left by the wavefront tilt correction system. The final result is summarized in a table which shows the value of visibility for the four main subsystems in which the interferometer has been divided: the product of these values gives the instrumental visibility for IOTA. Since most of the instrumental parameters are already fixed, the main contribution of this evaluation consists in the estimation of the potential of the instrument in terms of both visibility and magnitude limit (the signal-to-noise ratio of the measurement depends on the visibility) of the IOTA interferometer. In this section I present the study developed to get a strawman design for the lunar interferometer. In this study I take into consideration some characteristics of the IOTA design (initial system with two collectors, telescope con guration consisting in a siderostat plus a beam-compressor, two delay lines for the compensation of the optical path delay) which are analyzed to be properly make suitable for a lunar interferometer. I also deal with subjects which, even if not explicitly considered in the study for IOTA, constitute a fundamental part of the knowledge derived by working on IOTA, and need to be considered for the de nition of the lunar instrument. The last chapter, devoted to the evaluation of the visibility budget for the lunar interferometer, sums up the relations with the study performed for IOTA. I suggest the analogy between the contribution due to the atmosphere for a ground-based instrument and that due to the environment for a lunar one, and I evaluate the wavefront error related to di erent subsystems on the basis of the analyses performed for IOTA. However there is a main difference between the two cases. For IOTA I evaluated the instrumental visibility which derives from the already de ned instrument characteristics. On the contrary, for the lunar interferometer I first estimated a minimum value for the instrumental visibility so that the instrument has performances better than those of a ground-based instrument, and then I evaluated the maximum contribution to the wavefront error that each subsystem can give. When it was possible, I also derived the subsystem components' specifications which allow to meet the initial budget. In the first chapter (I) I deal with the orientation of the baseline and with the implication it has both on the variation of the optical path difference (OP D) and on the u-v plane coverage (which is the quantity that determines the imaging performance of the instrument). In the rst part of the chapter I obtain the expressions, as a function of the Moon rotation, for the calculation of the OPD variation and of its rate of variation. Then I show the results for two specific cases: baseline orientation N-S and E-W. In the second part of the chapter I present the results for the u-v coverage obtained with di erent baseline orientations. I considered three orientations (N-S, E-W, NW-SE) and for each of them I evaluated the u-v coverage for three di erent baseline latitudes and three di erent object declinations. In the second chapter (II) I present the analysis on the telescope configuration. In particular, I considered the con guration adopted for IOTA, which consists in a siderostat followed by an afocal beam-compressor. I show that by defining two angular parameters, the maximum and the minimum incidence angle on the siderostat, we can derive a set of conditions and consequent trade-o s related to: the declination and hour angle ranges available for observation, the dimensions of the siderostat and the compactness of the telescope structure. I first explain the reasons for the choice of the siderostat plus beamcompressor solution for the lunar interferometer, then most of the chapter is devoted to the analysis of the telescope parameters. In the last part, I also take into consideration other aspects related to the telescope con guration which are not main drivers for the de nition of the telescope parameters. In the third chapter (III) I deal with the lunar thermal environment and I present the thermal analysis for one of the telescopes of the interferometer. The lunar thermal environment implies extreme conditions for the operation of any instrument and severe constraints may be imposed on the components of an interferometer, as it can be suggested on the basis of the study on the thermal effects performed for IOTA. Without a suited thermal control system, these thermal conditions may cause permanent misalignments of the telescope optics, introduce structural deformations, and damage mechanical and electronic systems. In the first part of the chapter I present an analysis of the thermal characteristics of the lunar surface. It is based on the study, by Cremers et al. (1972), of some samples of lunar soil collected during the Apollo 12 mission. In the second part I present the results of the thermal analysis, performed by Sherry Walker of the NASA Marshall Space Center, of a 16 m lunar telescope. On the basis of several interaction and discussion with engineer Walker I was able to adapt these results to the case of a 1 m telescope, which is the size of the telescope that I would expect for a lunar interferometer. In the third part of the chapter I present the results to be applied for this case, which consist in the temperature and the temperature variations, relative to three periods of the lunar night and two periods of the day, to which the telescope is exposed. Finally, the Appendix L is a complementary part of this chapter: in it I speci cally deal with some e ects induced on the primary mirror by the thermal environment. The data I present are due to a study which Hughes Danbury Optical System, Inc. performed for the selection of the material and the geometry of the primary mirror of LUTE (Lunar Ultraviolet Telescope Experiment). I used the results obtained by Hughes to estimate an appropriate temperature range within which the lunar interferometer should be kept. This result is important because it constitute the starting point for the analysis of the subsystem interactions which I present in the following chapter. In the forth chapter (IV) I give an example of the relations among the parameters of different subsystems and show how the choice of the value of these parameters depends on the environmental conditions. In order to de ne the set of parameters which characterize the strawman design that I propose, I make use of the results from the analyses presented in the chapters Thermal analysis for a telescope of the lunar interferometer, The siderostat plus beam-compressor solution for a lunar interferometer, and Baseline orientation: OPD variation and u-v coverage. The instrument consists in two collectors separated by a baseline 1 km long, and it will operate only during the lunar night. From the results of the thermal analysis, in particular those related to the period of radiative equilibrium for the telescope, I derived the hour angle range which is available for observations. On the basis of this result I determine the other parameters which de ne the telescope con guration. Finally, I consider the baseline orientation and calculate the u-v coverage obtainable with the maximum integration time (de ned by the hour angle range previously found) available. I show the results of this exercise for two di erent baseline latitude, 0 and 30 , and from their comparison I suggest the following preliminary instrument design: ; two-element interferometer with a baseline of 1 km ; each telescope is provided of a dome-shade which allows to keep within 100 K the maximum temperature variation su ered by the telescope ; equatorial baseline with E-W orientation ; the optical path difference compensation is realized by means of two delay lines: a coarse delay line with 5 fixed station separated by 100 m a ne delay line, movable, with maximum length of 50 m ; maximum integration time of 130 h ; telescope oriented in direction E-W and tilted by 35 with respect to the horizontal ; primary mirror diameter of 1 m. This preliminary design should be considered as the starting point for a detailed evaluation of the constraints on the instrument components and the de nition, for the parameters involved, of one set of values which allows to reach the mission objectives. In the fth chapter (V) I deal with the lunar environment and in particular with those aspects which have main impacts on the operation of a lunar interferometer. The description I present is mainly based on the results of experiments performed during the Surveyor 3 and several Apollo missions. I provide more detailed information about the e ects induced by the lunar dust and the lunar seismic activity, since both of them may signi cantly a ect the operation of an interferometer. Other subjects I take into consideration are the ux of meteoroids, the characterization of the lunar atmosphere, and the cosmic and solar radiation that reaches the lunar surface. I do not deal with the thermal environment which is already described in the chapter on the thermal analysis of the telescope. In the sixth chapter (VI) I perform, as I did for the study on IOTA, a global estimation of the lunar interferometer performances by means of the visibility budget of the instrument. In order to work out a realistic budget it is necessary to know the architecture of the whole design, to single out the main subsystems and to determine their contribution to the degradation of the instrument performance, by taking into account each subsystem architecture, its interaction with the other subsystems and with the environment. Since the visibility budget is one of the means to determine the instrument potential, it is also a means to evaluate the worthwhileness of a lunar interferometer project. In the first part of the chapter I determine the visibility goal for the instrument, by taking into account the best performances expected for a ground-based interferometer of the next generation. In this context, in order to characterize the causes of visibility loss, I introduce the analogy between the role played by the atmosphere for a ground-based interferometer and that played by the environment for a lunar interferometer. In the second part of the chapter I take into consideration various causes of visibility loss which may a ect the components of the four main subsystems of the instrument (in particular visibility loss related to the optical components, to a variation of the optical path difference during an integration time, to di raction e ects on the transmitted beam, and to the servo control system for the correction of tilt of the beam). When it is possible, I allocate to each item a value of visibility loss which allows to meet the suggested visibility goal. The result of this analysis shows the need of improving, both qualitatively and quantitatively, our knowledge about the lunar environment expecially for those aspects which mainly a ects the operation an interferometer. This can be achieved by means of one or several missions designed to perform in situ experiments to measure the parameters which characterize the thermal environment, the seismic activity, the dust transport mechanism, and the lunar atmosphere. Two missions which, in the near future, could provide part of these information are LUNAR-A and LEDA, and they are brie y described in the conclusion chapter of this work.

  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] Mueller and Ferrin, Icarus 123, 463, 1996 [6] Sekanina, AJ 102, 350, 1991 [7] Schleicher et al., BAAS 41, 1028, 2009 [8] Sykes et al, Icarus 86, 236, 1990 [9] Wisniewsi, Icarus 86, 52, 1990

  4. 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.

  5. Low probability of intercept radar

    NASA Astrophysics Data System (ADS)

    Schleher, D. C.

    The objective of LPI radars is defined and performance characteristics are examined. A performance criterion relating the range at which the LPI radar can detect a target to the range at which an intercept receiver aboard the target can detect the LPI radar is defined. The response of various operational and advanced intercept receivers to wideband LPI radar waveforms is explored. The performance criterion is evaluated as a function of the LPI radars time-bandwidth product and sidelobe response (both ordinary and ultralow) for a number of operational and advanced intercept receivers. An ambiguity diagram that provides the response of the intercept receiver to the LPI waveform for mismatches in receiver time and frequency response is described. The ambiguity diagram is evaluated for various mismatched receivers. A processor is discussed that improves the response of intercept receivers to pulse compression radar waveforms.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Radar studies of bird migration

    NASA Technical Reports Server (NTRS)

    Williams, T. C.; Williams, J. M.

    1974-01-01

    Observations of bird migration with NASA radars were made at Wallops Island, Va. Simultaneous observations were made at a number of radar sites in the North Atlantic Ocean in an effort to discover what happened to those birds that were observed leaving the coast of North America headed toward Bermuda, the Caribbean and South America. Transatlantic migration, utilizing observations from a large number of radars is discussed. Detailed studies of bird movements at Wallops Island are presented.

  11. Goldstone radar observations of Mercury

    NASA Technical Reports Server (NTRS)

    Clark, P. E.; Jurgens, R. F.; Leake, M. A.

    1988-01-01

    Radar observations of Mercury were made during the past two decades at the Goldstone radar facility. Correlations of these observations with geologic maps are presented in this chapter. Topographic profiles indicate that Mercurian craters are rather shallow. Some topographic features are seen on the side of Mercury not imaged by Mariner 10. There are global correlations between topography and radar roughness. Mercury's surface may be rougher on a 1-cm scale than on a 10-cm scale, in comparison with the moon.

  12. 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.

  13. 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.

  14. 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.

  15. An Imaging Interferometer for Terrestrial Remote Sensing

    NASA Technical Reports Server (NTRS)

    Hammer, Philip D.; Valero, Francisco P. J.; Peterson, David L.; Smith, William Hayden

    1993-01-01

    A prototype imaging interferometer called DASI (digital array scanned interferometer) is under development at our laboratories. Our objective is to design an instrument for remote sensing of Earth's atmosphere and surface. This paper describes the unusual characteristics of DASIs which make them promising candidates for ground and aircraft-based terrestrial measurements. These characteristics include superior signal-to-noise, design simplicity and compactness, relative to dispersion based imaging spectrometers. Perhaps one of the most notable features of DASIs is their ability to acquire an entire interferogram simultaneously without any moving optical elements. We also describe selected laboratory and ground based field measurements using the prototype DASI. A CCD detector array was placed at the DASI detector plane for wavelength coverage from 0.4 to 1.0 micron. A NICMOS MCT detector was used for coverage from 1.1 to 2.2 micron. The DASI was configured to have a spectral resolution of about 300 1/cm, a spatial field of view of 5 degrees, and a constant number of transverse spatial elements (detector dependent) for each exposure frame. Frame exposure rates were up to 0.6 Hz with the potential to achieve 5 Hz. Image cube measurements of laboratory targets and terrestrial scenes were obtained by multiple frame scanning over the field of view. These data sets reveal the potential science yields from obtaining simultaneous high resolution spatial and spectral information.

  16. Advanced lightning location interferometer. Final report

    SciTech Connect

    1995-05-25

    In January, 1994, New Mexico Institute for Mining and Technology (NM Tech) was commissioned by Los Alamos National Laboratories (LANL) to develop a three-axis interferometric lightning mapping system to be used in determining the source of certain frequency-dispersed pulse pairs which had been detected by spaceborne sensors. The existing NM Tech VHF Lightning Interferometer was a two axis system operating at 274 MHz with 6 MHz bandwidth. The third axis was to be added to refine estimates of the elevation angle to distant RF sources in that band. The system was to be initially deployed in support of an Air Force Technical Applications Center (AFTAC) effort planned for the Kennedy Space Center/Cape Canaveral AFS area in June-July of 1994. The project was, however, postponed until September of 1994. The interferometer was set up and operated at KSC near the Lightning Detection and Ranging (LDAR) central station. The initial setup was in two-axis configuration, and the third (vertical) axis was added at about mid-project. Though the storms were reduced in frequency and severity over what one would expect in mid-summer, several good data sets were obtained and delivered to AFTAC.

  17. Automated calibration system for laser interferometers

    NASA Astrophysics Data System (ADS)

    Tang, Chung-Chi; Cheng, Kai-Yu

    2003-11-01

    For dimensional measurements and positioning, laser interferometers are often used to obtain highly accurate readings. To service their reliability, a system of laser interferometry standards is made available at the National Measurement Laboratory to offer instrument calibration as well as to ensure their traceability to the SI units. Owing much to their great sensitivity, the accuracy of laser interferometers undergoing calibration is strictly influenced by surrounding conditions, especially the correction parameter in the refractive index of air - a complex combination of ambient temperature, humidity, and atmosphere pressure. In order to minimize the deviation, an automated calibration system is constructed by employing a computer-controlled driver stage to perform linear displacement and data acquisition in the absence of operator intervention. A supplementary displacement measurement sub-system was set up to serve as an independent control on the stage. An average of 12 data points were taken at each predefined positions along the 20-m travel to support the comparison between the original system and the automated one. Several test runs from the calibration operation showed a standard deviation of 2.4×10-8 for the automated system and 6.5×10-8 for the previous. In addition to lower operational cost, experimental data also indicated improved calibration reliability benefited from the automation.

  18. Retrievals with the Infrared Atmospheric Sounding Interferometer

    NASA Technical Reports Server (NTRS)

    Zhou, Daniel K.; Liu, Xu; Larar, Allen M.; Smith, William L.; Taylor, Jonathan P.; Schlussel, Peter; Strow, L. Larrabee; Calbet, Xavier; Mango, Stephen A.

    2007-01-01

    The Infrared Atmospheric Sounding Interferometer (IASI) on the MetOp satellite was launched on October 19, 2006. The Joint Airborne IASI Validation Experiment (JAIVEx) was conducted during April 2007 mainly for validation of the IASI on the MetOp satellite. IASI possesses an ultra-spectral resolution of 0.25/cm and a spectral coverage from 645 to 2760/cm. Ultraspectral resolution infrared spectral radiance obtained from near nadir observations provide atmospheric, surface, and cloud property information. An advanced retrieval algorithm with a fast radiative transfer model, including cloud effects, is used for atmospheric profile and cloud parameter retrieval. Preliminary retrievals of atmospheric soundings, surface properties, and cloud optical/microphysical properties with the IASI observations during the JAIVEx are obtained and presented. These retrievals are further inter-compared with those obtained from airborne FTS system, such as the NPOESS Airborne Sounder Testbed Interferometer (NAST-I), dedicated dropsondes, radiosondes, and ground based Raman Lidar. The capabilities of satellite ultra-spectral sounder such as the IASI are investigated.

  19. Ultraviolet-Infrared Mapping Interferometic Spectrometer

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Prism and grating spectrometers have been the defacto devices for spectral mapping and imaging (hereafter referred to as hyperspectra). We have developed a new, hybrid instrument with many superior capabilities, the Digital Array Scanned Interferometer, DASI. The DASI performs the hyperspectral data acquisition in the same way as a grating or prism spectrograph, but retains the substantial advantages of the two-beam (Michelson) interferometer with additional capabilities not possessed by either of the other devices. The DASI is capable of hyperspectral studies in virtually any space or surface environment at any wavelength from below 50 nm to beyond 12 microns with available array detectors. By our efforts, we have defined simple, low cost, no-moving parts DASI's capable of carrying out hyperspectral science measurements for solar system exploration missions, e.g. for martian, asteroid, lunar, or cometary surveys. DASI capabilities can be utilized to minimize cost, weight, power, pointing, and other physical requirements while maximizing the science data return for spectral mapping missions. Our success in the development of DASI's has become and continues to be an important influence on the efforts of the best research groups developing remote sensing instruments for space and other applications.

  20. 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.

  1. Reconfigurable L-Band Radar

    NASA Technical Reports Server (NTRS)

    Rincon, Rafael F.

    2008-01-01

    The reconfigurable L-Band radar is an ongoing development at NASA/GSFC that exploits the capability inherently in phased array radar systems with a state-of-the-art data acquisition and real-time processor in order to enable multi-mode measurement techniques in a single radar architecture. The development leverages on the L-Band Imaging Scatterometer, a radar system designed for the development and testing of new radar techniques; and the custom-built DBSAR processor, a highly reconfigurable, high speed data acquisition and processing system. The radar modes currently implemented include scatterometer, synthetic aperture radar, and altimetry; and plans to add new modes such as radiometry and bi-static GNSS signals are being formulated. This development is aimed at enhancing the radar remote sensing capabilities for airborne and spaceborne applications in support of Earth Science and planetary exploration This paper describes the design of the radar and processor systems, explains the operational modes, and discusses preliminary measurements and future plans.

  2. Python-ARM Radar Toolkit

    SciTech Connect

    2013-03-17

    The Python-ARM Radar Toolkit (Py-ART) is a collection of radar quality control and retrieval codes which all work on two unifying Python objects: the PyRadar and PyGrid objects. By building ingests to several popular radar formats and then abstracting the interface Py-ART greatly simplifies data processing over several other available utilities. In addition Py-ART makes use of Numpy arrays as its primary storage mechanism enabling use of existing and extensive community software tools.

  3. Temperature Measurement Using all Fiber Fabry-Perot Interferometers Based on Phase Measurement Between Reference and Sensing Interferometer Spectral Characteristic

    NASA Astrophysics Data System (ADS)

    Njegovec, Matej; ?onlagic, Denis

    2010-04-01

    This paper presents the signal interrogator for fiber optic temperature sensors based on all-fiber miniature Fabry-Perot interferometers that are implemented by creation of the low reflectivity mirrors within optical fiber. This kind of Fabry-Perot interferometer has low finesse and nearly sinusoidal spectral characteristics. Since the optical path length between mirrors depends on refractive index and thereby temperature, change in sensor temperature shifts the sensor's spectral characteristics in wavelength domain. The presented measurement system is composed of the sensing interferometer and signal interrogator that further includes the reference interferometer. The reference interferometer is also an all-fiber interferometer with nearly identical length as sensing interferometer. The wavelength of the signal interrogator optical source was cyclically swept over available wavelength range while both interferometers' spectral responses were simultaneously recorded. The optical path length variation of the sensing interferometer was determined by direct phase difference measurement between both recorded sinusoidal spectral characteristics. This phase difference was directly correlated to the temperature difference between sensing and reference interferometer. Since reference interferometer was situated within the signal integrator its temperature was measured by the reference electrical sensors. Thus the proposed system can provide accurate absolute temperature measurements. In the proposed interrogator we used as an optical source a standard telecommunication DFB diode module with integrated thermo-electric cooler. Standard DFB diode can be shifted in wavelength for abut 2 nm, which allows interrogation of the Fabry-Perot interferometers having free spectral range below 2 nm. In case of an all fiber Fabry-Perot interferometers, this corresponds to interferometers with length that is more than 0.5 mm. Since recorded nearly sinusoidal spectral characteristics include single or few periods including various non idealities, various phase difference measurement algorithms and signal preconditioning methods were investigated. Spectral characteristic phase difference resolution of abut 3.5e-3 rad was achieved in real physical system, witch corresponds to resolution of 0.3 °C in case of 1 mm long sensing and reference interferometer. The estimated absolute accuracy of the system was about 0.5 °C. System was build with only few relatively standard telecommunication optoelectronic components and it is therefore simple to implement and potentially cost effective.

  4. Improvements on calibration measurements with a Martin Puplett interferometer

    NASA Astrophysics Data System (ADS)

    Colin, Angel

    2007-09-01

    We describe a simple and efficient improvement to the Martin-Puplett interferometer, built at the Max-Planck Institute for Radioastronomy in Bonn. Interferograms with its corresponding spectra taken with the interferometer operating in the vacuum mode, have confirmed that the detector's signal increases up to ˜10% when the microwave foam absorbers used as radiation sources are replaced by blackbody cavities.

  5. Two-Dimensional X-Ray Grating Interferometer

    SciTech Connect

    Zanette, Irene; Weitkamp, Timm; Donath, Tilman; Rutishauser, Simon; David, Christian

    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.

  6. Silicon Carbide Mounts for Fabry-Perot Interferometers

    NASA Technical Reports Server (NTRS)

    Lindemann, Scott

    2011-01-01

    Etalon mounts for tunable Fabry- Perot interferometers can now be fabricated from reaction-bonded silicon carbide structural components. These mounts are rigid, lightweight, and thermally stable. The fabrication of these mounts involves the exploitation of post-casting capabilities that (1) enable creation of monolithic structures having reduced (in comparison with prior such structures) degrees of material inhomogeneity and (2) reduce the need for fastening hardware and accommodations. Such silicon carbide mounts could be used to make lightweight Fabry-Perot interferometers or could be modified for use as general lightweight optical mounts. Heretofore, tunable Fabry-Perot interferometer structures, including mounting hardware, have been made from the low-thermal-expansion material Invar (a nickel/iron alloy) in order to obtain the thermal stability required for spectroscopic applications for which such interferometers are typically designed. However, the high mass density of Invar structures is disadvantageous in applications in which there are requirements to minimize mass. Silicon carbide etalon mounts have been incorporated into a tunable Fabry-Perot interferometer of a prior design that originally called for Invar structural components. The strength, thermal stability, and survivability of the interferometer as thus modified are similar to those of the interferometer as originally designed, but the mass of the modified interferometer is significantly less than the mass of the original version.

  7. 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.

    2006-01-01

    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. The confocal interferometer's unique properties allow a simultaneous increase in both etendue and spectral power. Methods: We have constructed and tested two confocal interferometers. Conclusions: In this paper we compare the confocal interferometer with other spectral imaging filters, provide initial design parameters, show construction details for two designs, and report on the laboratory test results for these interferometers, and propose a multiple etalon system for future testing of these units and to obtain sub-picometer spectral resolution information on the photosphere in both the visible and near-infrared.

  8. Monolithic interferometer for high precision radial velocity measurements

    NASA Astrophysics Data System (ADS)

    Wan, Xiaoke; Ge, Jian; Wang, Ji; Lee, Brian

    2009-08-01

    In high precision radial velocity (RV) measurements for extrasolar planets searching and studies, a stable wide field Michelson interferometer is very critical in Exoplanet Tracker (ET) instruments. Adopting a new design, monolithic interferometers are homogenous and continuous in thermal expansion, and field compensation and thermal compensation are both satisfied. Interferometer design and fabrication are decrypted in details. In performance evaluations, field angle is typically 22° and thermal sensitivity is typically -1.7 x 10-6/°C, which corresponds to ~500 m/s /°C in RV scale. In interferometer stability monitoring using a wavelength stabilized laser source, phase shift data was continuously recorded for nearly seven days. Appling a frequent calibration every 30 minutes as in typical star observations, the interferometer instability contributes less than 1.4 m/s in RV error, in a conservative estimation.

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

    NASA Astrophysics Data System (ADS)

    Akiyama, T.; Yasuhara, R.; Kawahata, K.; Okajima, S.; Nakayama, K.

    2014-11-01

    Since a dispersion interferometer is insensitive to mechanical vibrations, a vibration compensation system is not necessary. The CO2 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 × 1017 m-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 × 1020 m-3 can be overcome by a sufficient sampling rate of about 100 kHz.

  10. Interferometers for Displacement-Noise-Free Gravitational-Wave Detection

    SciTech Connect

    Chen, Yanbei; Pai, Archana; Somiya, Kentaro; Kawamura, Seiji; Sato, Shuichi; Kokeyama, Keiko; Ward, Robert L.; Goda, Keisuke; Mikhailov, Eugeniy E.

    2006-10-13

    We propose a class of displacement- and laser-noise-free gravitational-wave-interferometer configurations, which does not sense nongeodesic mirror motion and laser noise, but provides a nonvanishing gravitational-wave signal. Our interferometers consist of four mirrors and two beam splitters, which form four Mach-Zehnder interferometers. By contrast to previous works, no composite mirrors with multiple reflective surfaces are required. Each mirror in our configuration is sensed redundantly, by at least two pairs of incident and reflected beams. Displacement- and laser-noise-free detection is achieved when output signals from these four interferometers are combined appropriately. Our 3-dimensional interferometer configuration has a low-frequency response proportional to f{sup 2}, which is better than the f{sup 3} achievable by previous 2-dimensional configurations.

  11. SU(1,1)-type light-atom-correlated interferometer

    NASA Astrophysics Data System (ADS)

    Ma, Hongmei; Li, Dong; Yuan, Chun-Hua; Chen, L. Q.; Ou, Z. Y.; Zhang, Weiping

    2015-08-01

    The quantum correlation of light and atomic collective excitation can be used to compose an SU(1,1)-type hybrid light-atom interferometer, where one arm in the optical SU(1,1) interferometer is replaced by the atomic collective excitation. The phase-sensing probes include not only the photon field but also the atomic collective excitation inside the interferometer. For a coherent squeezed state as the phase-sensing field, the phase sensitivity can approach the Heisenberg limit under the optimal conditions. We also study the effects of the loss of light field and the dephasing of atomic excitation on the phase sensitivity. This kind of active SU(1,1) interferometer can also be realized in other systems, such as circuit quantum electrodynamics in microwave systems, which provides a different method for basic measurement using the hybrid interferometers.

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

    SciTech Connect

    Akiyama, T. Yasuhara, R.; Kawahata, K.; Okajima, S.; Nakayama, K.

    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.

  13. Developing an Interferometer to Measure the Global 21cm Monopole

    NASA Astrophysics Data System (ADS)

    Domagalski, Rachel; Patra, Nipanjana; Day, Cherie; Parsons, Aaron

    2016-01-01

    When radio interferometers observe over very small fields of view, they cannot measure the monopole mode of the sky. However, when the field of view extends to a large region of the sky, it becomes possible to use an measure the monopole with an interferometer. We are currently developing such an interferometer at UC Berkeley's Radio Astronomy Lab (RAL) with the goal of measuring the early stages of the Epoch of Reionization by probing the sky for the global 21cm signal between 50 and 100 MHz, and we have deployed a preliminary version of this experiment in Colorado. We present the current status of the interferometer, the future development plans, and some measurements taken in July of 2015. These measurements demonstrate performance of the analog signal chain of the interferometer as well as the RFI environment of the deployment site in Colorado.

  14. Thermodynamic properties of a quantum Hall anti-dot interferometer

    NASA Astrophysics Data System (ADS)

    Levy Schreier, Sarah; Stern, Ady; Rosenow, Bernd; Halperin, Bertrand I.

    2016-02-01

    We study quantum Hall interferometers in which the interference loop encircles a quantum anti-dot. We base our study on thermodynamic considerations, which we believe reflect the essential aspects of interference transport phenomena. We find that similar to the more conventional Fabry-Perot quantum Hall interferometers, in which the interference loop forms a quantum dot, the anti-dot interferometer is affected by the electro-static Coulomb interaction between the edge modes defining the loop. We show that in the Aharonov-Bohm regime, in which effects of fractional statistics should be visible, is easier to access in interferometers based on anti-dots than in those based on dots. We discuss the relevance of our results to recent measurements on anti-dots interferometers.

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

    DOEpatents

    Ormesher, Richard C.; Axline, Robert M.

    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.

  16. 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.

  17. 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.

  18. 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.

  19. Doppler radar flowmeter

    DOEpatents

    Petlevich, Walter J.; Sverdrup, Edward F.

    1978-01-01

    A Doppler radar flowmeter comprises a transceiver which produces an audio frequency output related to the Doppler shift in frequency between radio waves backscattered from particulate matter carried in a fluid and the radiated radio waves. A variable gain amplifier and low pass filter are provided for amplifying and filtering the transceiver output. A frequency counter having a variable triggering level is also provided to determine the magnitude of the Doppler shift. A calibration method is disclosed wherein the amplifier gain and frequency counter trigger level are adjusted to achieve plateaus in the output of the frequency counter and thereby allow calibration without the necessity of being able to visually observe the flow.

  20. Thermal effects in the Input Optics of the Enhanced Laser Interferometer Gravitational-Wave Observatory interferometers

    NASA Astrophysics Data System (ADS)

    Dooley, Katherine L.; Arain, Muzammil A.; Feldbaum, David; Frolov, Valery V.; Heintze, Matthew; Hoak, Daniel; Khazanov, Efim A.; Lucianetti, Antonio; Martin, Rodica M.; Mueller, Guido; Palashov, Oleg; Quetschke, Volker; Reitze, David H.; Savage, R. L.; Tanner, D. B.; Williams, Luke F.; Wu, Wan

    2012-03-01

    We present the design and performance of the LIGO Input Optics subsystem as implemented for the sixth science run of the LIGO interferometers. The Initial LIGO Input Optics experienced thermal side effects when operating with 7 W input power. We designed, built, and implemented improved versions of the Input Optics for Enhanced LIGO, an incremental upgrade to the Initial LIGO interferometers, designed to run with 30 W input power. At four times the power of Initial LIGO, the Enhanced LIGO Input Optics demonstrated improved performance including better optical isolation, less thermal drift, minimal thermal lensing, and higher optical efficiency. The success of the Input Optics design fosters confidence for its ability to perform well in Advanced LIGO.

  1. Towards a Suspension Platform Interferometer for the AEI 10 m Prototype Interferometer

    NASA Astrophysics Data System (ADS)

    Dahl, K.; Bertolini, A.; Born, M.; Chen, Y.; Gering, D.; Goßler, S.; Gräf, C.; Heinzel, G.; Hild, S.; Kawazoe, F.; Kranz, O.; Kühn, G.; Lück, H.; Mossavi, K.; Schnabel, R.; Somiya, K.; Strain, K. A.; Taylor, J. R.; Wanner, A.; Westphal, T.; Willke, B.; Danzmann, K.

    2010-05-01

    Currently, the AEI 10 m Prototype is being set up at the Albert Einstein Institute in Hannover, Germany. The Suspension Platform Interferometer (SPI) will be an additional interferometer set up inside the vacuum envelope of the AEI 10 m Prototype. It will interferometrically link the three suspended in-vacuum tables. The inter-table distance will be 11.65 m. The SPI will measure and stabilise the relative motions between these tables for all degrees of freedom, except roll around the optical axis. In this way, all tables can be regarded as one large platform. The design goal is 100 pm/ differential distance stability between 10mHz and 100Hz.

  2. SMAP's Radar OBP Algorithm Development

    NASA Technical Reports Server (NTRS)

    Le, Charles; Spencer, Michael W.; Veilleux, Louise; Chan, Samuel; He, Yutao; Zheng, Jason; Nguyen, Kayla

    2009-01-01

    An approach for algorithm specifications and development is described for SMAP's radar onboard processor with multi-stage demodulation and decimation bandpass digital filter. Point target simulation is used to verify and validate the filter design with the usual radar performance parameters. Preliminary FPGA implementation is also discussed.

  3. Review of United Kingdom radar

    NASA Astrophysics Data System (ADS)

    Clarke, J.; Davies, D. E. N.; Radford, M. F.

    1984-09-01

    A review of primary radar systems in the United Kingdom that have recently entered service or are at an advanced stage of development is presented. Naval, airborn, and land-based types are all discussed covering both civil and military interests, although particular emphasis is given to airborne equipments. Some general supporting radar technology including university programs is also covered.

  4. Cassini Radar Investigation of Titan

    NASA Technical Reports Server (NTRS)

    Wall, S.; Elachi, C.; Roth, L.

    1995-01-01

    Saturn's largest moon, Titan, boasts organic chemistry that may hold clues to how life formed on the primitive Earth. The Cassini Mission, to be launched in October 1997, will explore Saturn and its moons, especially Titan. Mapping the surface of Titan will be accomplished with a radar instrument that acts as a 14 GHz synthetic aperture radar, microwave radiometer, altimeter, and scatterometer.

  5. 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.

  6. Millimeter radar improves target identification

    NASA Astrophysics Data System (ADS)

    McAulay, Alastair D.

    2011-06-01

    Recently developed millimeter wave radar has advantages for target identification over conventional microwave radar which typically use lower frequencies. We describe the pertinent features involved in the construction of the new millimeter wave radar, the pseudo-optical cavity source and the quasi-optical duplexer. The long wavelength relative to light allows the radar beam to penetrate through most weather because the wavelength is larger than the particle size for dust, drizzle rain, fog. Further the mm wave beam passes through an atmospheric transmission window that provides a dip in attenuation. The higher frequency than conventional radar provides higher Doppler frequencies, for example, than X-band radar. We show by simulation that small characteristic vibrations and slow turns of an aircraft become visible so that the Doppler signature improves identification. The higher frequency also reduces beam width, which increases transmit and receive antenna gains. For the same power the transmit beam extends to farther range and the increase in receive antenna gain increases signal to noise ratio for improved detection and identification. The narrower beam can also reduce clutter and reject other noise more readily. We show by simulation that the radar can be used at lower elevations over the sea than conventional radar.

  7. 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.

  8. Over-under double-pass interferometer

    NASA Technical Reports Server (NTRS)

    Schindler, R. A. (Inventor)

    1977-01-01

    An over-under double pass interferometer in which the beamsplitter area and thickness can be reduced to conform only with optical flatness considerations was achieved by offsetting the optical center line of one cat's-eye retroreflector relative to the optical center line of the other in order that one split beam be folded into a plane distinct from the other folded split beam. The beamsplitter is made transparent in one area for a first folded beam to be passed to a mirror for doubling back and is made totally reflective in another area for the second folded beam to be reflected to a mirror for doubling back. The two beams thus doubled back are combined in the central, beamsplitting area of the beamsplitting and passed to a detector. This makes the beamsplitter insensitive to minimum thickness requirements and selection of material.

  9. TFTR Michelson interferometer electron cyclotron emission diagnostic

    NASA Astrophysics Data System (ADS)

    Stauffer, F. J.; Boyd, D. A.; Cutler, R. C.; McCarthy, M. P.

    1985-05-01

    In July 1984, a Fourier transform spectrometer employing a fast-scanning Michelson interferometer began operating on TFTR. This diagnostic system can measure the electron cyclotron emission spectrum 72 times per s with a time resolution of 11 ms and a spectral resolution of 3.6 GHz. The initial operating spectral range is 75-540 GHz, which is adequate for measuring the first three cyclotron harmonics at present TFTR magnetic field levels. The range can be extended easily to 75-1080 GHz in order to accommodate increases in toroidal magnetic field or to study superthermal ECE. The measured spectra are absolutely calibrated using a liquid nitrogen cooled blackbody reference source. The second harmonic feature of each spectrum is used to calculate the absolute electron temperature profile.

  10. Heterodyne Interferometer with a Phase Modulated Source

    NASA Technical Reports Server (NTRS)

    Dubovitsky, Serge (Inventor)

    2004-01-01

    The present invention relates to a heterodyne interferometer system with a pre-processing of the target signal to isolate and remove self-interference signals using a known phase modulation of the carrier signal's frequency. Where self- interference signals do not include a time delay inherent in the target signal that travels to the target reflector, by selecting a modulation frequency tuned to the time delay and then filtering the resultant signal the target beam can be isolated and the self-interference signal can be effectively removed The system includes a modulation unit to apply a phase modulation to the carrier signal, and a mixing unit that demodulates the target signal at the modulation frequency to isolate the target beam.

  11. An 'X-banded' Tidbinbilla interferometer

    NASA Technical Reports Server (NTRS)

    Batty, Michael J.; Gardyne, R. G.; Gay, G. J.; Jauncy, David L.; Gulkis, S.; Kirk, A.

    1986-01-01

    The recent upgrading of the Tidbinbilla two-element interferometer to simultaneous S-band (2.3 GHz) and X-band (8.4 GHz) operation has provided a powerful new astronomical facility for weak radio source measurement in the Southern Hemisphere. The new X-band system has a minimum fringe spacing of 38 arcsec, and about the same positional measurement capability (approximately 2 arcsec) and sensitivity (1 s rms noise of 10 mJy) as the previous S-band system. However, the far lower confusion limit will allow detection and accurate positional measurements for sources as weak as a few millijanskys. This capability will be invaluable for observations of radio stars, X-ray sources and other weak, compact radio sources.

  12. Digital holographic interferometer with correction of distortions

    NASA Astrophysics Data System (ADS)

    Sevryugin, A. A.; Pulkin, S. A.; Tursunov, I. M.; Venediktov, D. V.; Venediktov, V. Y.

    2015-10-01

    The paper considers the use of holographic interferometer for hologram re-recording with correction of distortions. Each optical system contains some beam path deviations, called aberrations of the optical system. They are seen in the resulting interference pattern as a distortion of fringes. While increasing the sensitivity of the interference pattern by N times at the same time we introduce new aberrations, caused by re-recording setup in addition to aberrations that are already presented on the interferogram, caused by initial recording, also multiplied by N times. In this experiment we decided to use a modified setup with spatially combined interferograms with use of matrix spatial light modulator and digital image processing of the interferograms recorded by CCD or CMOS camera.

  13. The Very Large Telescope Interferometer v2012+

    NASA Astrophysics Data System (ADS)

    Haguenauer, Pierre; Abuter, Roberto; Andolfato, Luigi; Alonso, Jaime; Blanchard, Guillaume; Berger, Jean-Philippe; Bourget, Pierre; Brillant, Stephane; Derie, Frédéric; Delplancke, Françoise; Di Lieto, Nicola; Dupuy, Christophe; Gilli, Bruno; Gitton, Philippe; Gonzalez, Juan Carlos; Guisard, Stéphane; Guniat, Serge; Hudepohl, Gerhard; Kaufer, Andreas; Lévêque, Samuel; Ménardi, Serge; Mérand, Antoine; Morel, Sebastien; Percheron, Isabelle; Phan Duc, Than; Poupar, Sebastien; Ramirez, Andres; Reineiro, Claudio; Rengaswamy, Sridharan; Rivinius, Thomas; Schöller, Markus; Schmid, Christian; Segovia, Alex; Schuhler, Nicolas; Valdes, Guillermo; de Wit, Willem Jan; Wittkowski, Markus

    2012-07-01

    The ESO Very Large Telescope Interferometer (VLTI) offers access to the four 8-m Unit Telescopes (UT) and the four 1.8-m Auxiliary Telescopes (AT) of the Paranal Observatory located in the Atacama Desert in northern Chile. The two VLTI instruments, MIDI and AMBER deliver regular scientific results. In parallel to the operation, the instruments developments are pursued, and new modes are studied and commissioned to offer a wider range of scientific possibilities to the community and increase sensitivity. New configurations of the ATs have been offered and are frequently discussed with the science users of the VLTI and implemented to optimize the scientific return. The PRIMA instrument, bringing astrometry capability to the VLTI and phase referencing to the instruments is being commissioned. The visitor instrument PIONIER is now fully operational and bringing imaging capability to the VLTI. The current status of the VLTI is described with successes and scientific results, and prospects on future evolution are presented.

  14. The very large telescope Interferometer: 2010 edition

    NASA Astrophysics Data System (ADS)

    Haguenauer, Pierre; Alonso, Jaime; Bourget, Pierre; Brillant, Stephane; Gitton, Philippe; Guisard, Stephane; Poupar, Sébastien; Schuhler, Nicolas; Abuter, Roberto; Andolfato, Luigi; Blanchard, Guillaume; Berger, Jean-Philippe; Cortes, Angela; Dérie, Frédéric; Delplancke, Françoise; Di Lieto, Nicola; Dupuy, Christophe; Gilli, Bruno; Glindemann, Andreas; Guniat, Serge; Huedepohl, Gerhard; Kaufer, Andreas; Le Bouquin, Jean-Baptiste; Lév"que, Samuel; Ménardi, Serge; Mérand, Antoine; Morel, Sebastien; Percheron, Isabelle; Phan Duc, Than; Pino, Andres; Ramirez, Andres; Rengaswamy, Sridharan; Richichi, Andrea; Rivinius, Thomas; Sahlmann, Johannes; Schoeller, Markus; Schmid, Christian; Stefl, Stan; Valdes, Guillermo; van Belle, Gerard; Wehner, Stefan; Wittkowski, Markus

    2010-07-01

    The ESO Very Large Telescope Interferometer (VLTI) offers access to the four 8-m Unit Telescopes (UT) and the four 1.8-m Auxiliary Telescopes (AT) of the Paranal Observatory located in the Atacama Desert in northern Chile. The two VLTI instruments, MIDI and AMBER deliver regular scientific results. In parallel to the operation, the instruments developments are pursued, and new modes are studied and commissioned to offer a wider range of scientific possibilities to the community. New configurations of the ATs array are discussed with the science users of the VLTI and implemented to optimize the scientific return. The monitoring and improvement of the different systems of the VLTI is a continuous work. The PRIMA instrument, bringing astrometry capability to the VLTI and phase referencing to the instruments has been successfully installed and the commissioning is ongoing. The possibility for visiting instruments has been opened to the VLTI facility.

  15. Interferometers Sharpen Measurements for Better Telescopes

    NASA Technical Reports Server (NTRS)

    2013-01-01

    Over the last decade, there have been a number of innovations that have made possible the largest and most powerful telescope of its time: the James Webb Space Telescope (JWST). Scheduled to launch in 2018, JWST will provide insight into what the oldest, most distant galaxies look like. When engineers build a first-of-its-kind instrument like the JWST, they often must make new tools to construct the new technology. Throughout the decades of planning, development, and construction of the JWST, NASA has worked with numerous partners to spur innovations that have enabled the telescope s creation. Though the JWST s launch date is still several years away, a number of these innovations are spinning off to provide benefits here on Earth. One of these spinoffs has emerged from the extensive testing the JWST must undergo to ensure it will function in the extreme environment of space. In order to test the JWST instruments in conditions that closely resemble those in space, NASA uses a cryogenic vacuum chamber. By dropping the temperatures down to -400 F and employing powerful pumps to remove air from the chamber, engineers can test whether the JWST instruments will function once the spacecraft leaves Earth. Traditionally, a phase-shifting interferometer is used to measure optics like the JWST s mirrors to verify their precise shape, down to tens of nanometers, during manufacturing. However, the large size of the mirrors, coupled with vibration induced by the cryo-pumps, prohibits the use of traditional phase-shifting interferometers to measure the mirrors within the chamber environment. Because the JWST will be located in deep space, far from any possible manned service mission, it was essential to find a robust solution to guarantee the performance of the mirrors.

  16. The Millimeter-wave Bolometric Interferometer

    NASA Astrophysics Data System (ADS)

    Hyland, Peter Owen

    2008-12-01

    The Millimeter-wave Bolometeric Interferometer (MBI) is a novel instrument for measuring signals from the cosmic microwave background (CMB) radiation. MBI is a proof-of-concept designed to control systematic effects with the use of bolometers and interferometry. This scheme extends radio astronomy techniques of spatial interferometry, which rely on coherent receivers, to a system using incoherent detectors. In this thesis we outline the principles upon which MBI works and provide the reader with an understanding of both the particulars involved in the design and operation of MBI as well as the analysis of the resulting data. MBI observes the sky directly with 4 corrugated horn antennas in a band centered on l = 3 mm . A quasi-optical beam combiner forms interference fringes on an array of bolometers cooled to 300 mK. Phase modulation of the signals modulates the fringe patterns on the array and allows decoding of the visibilities formed by each pair of antennas. An altitude-azimuth mounting structure allows the horns to observe any point on the sky; rotation about the boresite extends the u - v coverage of the interferometer and allows for systematics checks and measurements of the Stokes parameters. MBI was deployed at the Pine Bluff Observatory near UW - Madison in winter 2008 for its first test observations of astronomical and artificial sources. Interference fringes were seen from a microwave generator located in the far- field, verifying our basic model of bolometric interferometry. Further analysis is needed to measure the scattering matrix of the instrument and to compare it against simulations.

  17. Control of the Laser Interferometer Space Antenna

    NASA Technical Reports Server (NTRS)

    Maghami, Peiman; Hyde, T. Tupper

    2003-01-01

    The detection of gravity waves will open a new window of observation on the universe. Unlike typical observatories, which detect electromagnetic waves traveling through space-time, the Laser Interferometer Space Antenna (LISA) will detect ripples in space-time itself. Science targets include galactic binaries, merging supermassive black holes, intermediate-mass/seed black holes, and cosmological backgrounds. Gravity waves are detected by measuring the strain in space, i.e. the change in distance between a set of masses (test masses or proof masses) separated by a great distance. Ground based detection of gravity waves by Laser Interferometer Gravitational Wave Observatory (LIGO) and other observatories are possible with laser interferometry; hut the relatively short arm length (4 km) and seismic noise limit the measurement band to above 10 Hz on Earth. LISA also uses laser interferometric measurement of the change in distance between test masses, but does it in space. Each LISA spacecraft embodies two test masses. Space allows very long arm lengths (5 million km for LISA) and a very quiet acceleration environment (3.5x10(exp -15) meters per second squared/Hertz (sup 0.5) for LISA), which allows for the detection of gravity wave strains to a best sensitivity of 3x10(exp -24) strain/Hertz (sup 0.5) over the measurement band of 10(exp -4) to 10(exp -1) Hertz for a one-year observation. The LISA mission consists of three spacecraft in heliocentric orbit. The orbits are chosen so that the three spacecraft form a roughly equilateral triangle with its center located at a radius of 1 AU and 20 degrees behind the Earth, as shown. Requirements are placed on the rotational and translational dynamics of each spacecraft to ensure that the proper sensitivity for science measurements can be achieved.

  18. Gravitational Waves Interferometers and the Virgo Project

    NASA Astrophysics Data System (ADS)

    Gaddi, A.

    2002-11-01

    Radio, optical and X-rays telescopes are improving our knowledge of deep space. All these telescopes detect electromagnetic radiation at various frequencies. But a different kind of radiation is generated in the deeper space; it is the gravitational one. Gravitational waves change the space-time metric. As a consequence, GW telescopes should detect an extremely small strain (h < 10-21) of the geometry of a reference frame; if the frame has a reference dimension (L) of some kilometers, the deformation amplitude (?L = h × L) is limited to 10-16 meters. Laser interferometers are the most suitable devices to make precise measurements of distances. Their resolution is limited by the laser wavelength (? = 10-6 meters) and by the light wave-shift detection capability (? ?= 1 ppb). These theoretical limits are strongly degraded by different noise sources, which reduce the actual resolution by several orders of magnitude. Applied physicists and engineers are working together to overcome the technical problems that still keep the distance between theoretical and actual detectors' performances. Three large GW telescopes, based on the laser interferometric technology, are under commissioning in the USA (2) and Europe (1). They will become operatives in the next years, with sensitivity of the order of h = 10-21, in the range between 10 Hz and a few kHz. Among the others, two characteristics are peculiar of the VIRGO interferometer: the high performance of the mirrors' seismic isolation system and the huge ultra high vacuum volume, that will result in the biggest UHV apparatus ever built all over Europe.

  19. FIR interferometer and scattering measurements of ATF

    SciTech Connect

    Ma, C.H.; Hutchinson, D.P.; Fockedey, Y.; Vander Sluis, K.L.; Bennett, C.A.

    1989-01-01

    A 15-channel far-infrared (FIR) interferometer system has been constructed to measure the electron densities on the ATF plasmas. The system consists of a pair of cw 214-..mu..m difluoromethane (CH/sub 2/F/sub 2/) lasers, optically pumped by separate CO/sub 2/ lasers. The large number of channels is achieved by the use of reflective beam expansion optics to create a beam of 2 cm /times/ 45 cm. After passing through the plasma discharge, the elongated beam produced by the cylindrical mirrors is dissected by an array of 15 off-axis paraboloid reflectors, each of which illuminates a single Schottky-diode detector. The use of the beam expanding optics system reduces the number of optical elements required for the interferometer to approximately 2-3 per channel. The FIR laser beams are transported from the laser room to the experimental area by 25 mm i.d. dielectric waveguides purged with dry nitrogen. The system can also be operated at a wavelength of 119-..mu..m by changing the gas in FIR laser cavities to methanol for high density experiments. Details of the system are described. A study is underway to determine the optimum design of a FIR scattering system for the ATF. This scattering system will be used to investigate density fluctuations with scale lengths from 0.1 cm to the plasma radius. The laser for this scattering system may be operated at wavelengths of 447, 307, 214, 184, and 119 ..mu..m with power levels of 100 to 500 mW. A summary of the study is presented. 6 refs., 1 fig.

  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. Radar SLAM using visual features

    NASA Astrophysics Data System (ADS)

    Callmer, Jonas; Törnqvist, David; Gustafsson, Fredrik; Svensson, Henrik; Carlbom, Pelle

    2011-12-01

    A vessel navigating in a critical environment such as an archipelago requires very accurate movement estimates. Intentional or unintentional jamming makes GPS unreliable as the only source of information and an additional independent supporting navigation system should be used. In this paper, we suggest estimating the vessel movements using a sequence of radar images from the preexisting body-fixed radar. Island landmarks in the radar scans are tracked between multiple scans using visual features. This provides information not only about the position of the vessel but also of its course and velocity. We present here a navigation framework that requires no additional hardware than the already existing naval radar sensor. Experiments show that visual radar features can be used to accurately estimate the vessel trajectory over an extensive data set.

  2. 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.

  3. Low-brightness quantum radar

    NASA Astrophysics Data System (ADS)

    Lanzagorta, Marco

    2015-05-01

    One of the major scientific thrusts from recent years has been to try to harness quantum phenomena to dramatically increase the performance of a wide variety of classical information processing devices. These advances in quantum information science have had a considerable impact on the development of standoff sensors such as quantum radar. In this paper we analyze the theoretical performance of low-brightness quantum radar that uses entangled photon states. We use the detection error probability as a measure of sensing performance and the interception error probability as a measure of stealthiness. We compare the performance of quantum radar against a coherent light sensor (such as lidar) and classical radar. In particular, we restrict our analysis to the performance of low-brightness standoff sensors operating in a noisy environment. We show that, compared to the two classical standoff sensing devices, quantum radar is stealthier, more resilient to jamming, and more accurate for the detection of low reflectivity targets.

  4. Michelson-type Radio Interferometer for University Education

    NASA Astrophysics Data System (ADS)

    Koda, Jin; Barrett, J. W.; Hasegawa, T.; Hayashi, M.; Shafto, G.; Slechta, J.

    2013-01-01

    Despite the increasing importance of interferometry in astronomy, the lack of educational interferometers is an obstacle to training the futue generation of astronomers. Students need hands-on experiments to fully understand the basic concepts of interferometry. Professional interferometers are often too complicated for education, and it is difficult to guarantee access for classes in a university course. We have built a simple and affordable radio interferometer for education and used it for an undergraduate and graduate laboratory project. This interferometer's design is based on the Michelson & Peace's stellar optical interferometer, but operates at a radio wavelength using a commercial broadcast satellite dish and receiver. Two side mirrors are surfaced with kitchen aluminum foil and slide on a ladder, providing baseline coverage. This interferometer can resolve and measure the diameter of the Sun, a nice daytime experiment which can be carried out even under a marginal weather (i.e., partial cloud coverage). Commercial broadcast satellites provide convenient point sources. By comparing the Sun and satellites, students can learn how an interferometer works and resolves structures in the sky.

  5. Interferometer for Measuring Displacement to Within 20 pm

    NASA Technical Reports Server (NTRS)

    Zhao, Feng

    2003-01-01

    An optical heterodyne interferometer that can be used to measure linear displacements with an error <=20 pm has been developed. The remarkable accuracy of this interferometer is achieved through a design that includes (1) a wavefront split that reduces (relative to amplitude splits used in other interferometers) self interference and (2) a common-optical-path configuration that affords common-mode cancellation of the interference effects of thermal-expansion changes in optical-path lengths. The most popular method of displacement- measuring interferometry involves two beams, the polarizations of which are meant to be kept orthogonal upstream of the final interference location, where the difference between the phases of the two beams is measured. Polarization leakages (deviations from the desired perfect orthogonality) contaminate the phase measurement with periodic nonlinear errors. In commercial interferometers, these phase-measurement errors result in displacement errors in the approximate range of 1 to 10 nm. Moreover, because prior interferometers lack compensation for thermal-expansion changes in optical-path lengths, they are subject to additional displacement errors characterized by a temperature sensitivity of about 100 nm/K. Because the present interferometer does not utilize polarization in the separation and combination of the two interfering beams and because of the common-mode cancellation of thermal-expansion effects, the periodic nonlinear errors and the sensitivity to temperature changes are much smaller than in other interferometers

  6. Quantum metrology with parametric amplifier-based photon correlation interferometers

    PubMed Central

    Hudelist, F.; Kong, Jia; Liu, Cunjin; Jing, Jietai; Ou, Z.Y.; Zhang, Weiping

    2014-01-01

    Conventional interferometers usually utilize beam splitters for wave splitting and recombination. These interferometers are widely used for precision measurement. Their sensitivity for phase measurement is limited by the shot noise, which can be suppressed with squeezed states of light. Here we study a new type of interferometer in which the beam splitting and recombination elements are parametric amplifiers. We observe an improvement of 4.1±0.3 dB in signal-to-noise ratio compared with a conventional interferometer under the same operating condition, which is a 1.6-fold enhancement in rms phase measurement sensitivity beyond the shot noise limit. The improvement is due to signal enhancement. Combined with the squeezed state technique for shot noise suppression, this interferometer promises further improvement in sensitivity. Furthermore, because nonlinear processes are involved in this interferometer, we can couple a variety of different waves and form new types of hybrid interferometers, opening a door for many applications in metrology. PMID:24476950

  7. Mars Radar Observations with the Goldstone Solar System Radar

    NASA Technical Reports Server (NTRS)

    Haldemann, A. F. C.; Jurgens, R. F.; Larsen, K. W.; Arvidson, R. E.; Slade, M. A.

    2002-01-01

    The Goldstone Solar System Radar (GSSR) has successfully collected radar echo data from Mars over the past 30 years. As such, the GSSR has played a role as a specific mission element within Mars exploration. The older data provided local elevation information for Mars, along with radar scattering information with global resolution. Since the upgrade to the 70-m Deep Space Network (DSN) antenna at Goldstone completed in 1986, Mars data has been collected during all but the 1997 Mars opposition. Radar data, and non-imaging delay-Doppler data in particular, requires significant data processing to extract elevation, reflectivity and roughness of the reflecting surface. The spatial resolution of these experiments is typically some 20 km in longitude by some 150 km in latitude. The interpretation of these parameters while limited by the complexities of electromagnetic scattering, do provide information directly relevant to geophysical and geomorphic analyses of Mars. The usefulness of radar data for Mars exploration has been demonstrated in the past. Radar data were critical in assessing the Viking Lander 1 site as well as, more recently, the Pathfinder landing site. In general, radar data have not been available to the Mars exploration community at large. A project funded initially by the Mars Exploration Directorate Science Office at the Jet Propulsion Laboratory (JPL), and later funded by NASA's Mars Data Analysis Program has reprocessed to a common format a decade's worth of raw GSSR Mars delay-Doppler data in aid of landing site characterization for the Mars Program. These data will soon be submitted to the Planetary Data System (PDS). The radar data used were obtained between 1988 and 1995 by the GSSR, and comprise some 63 delay-Doppler radar tracks. Of these, 15 have yet to be recovered from old 9-track tapes, and some of the data may be permanently lost.

  8. Monolithic Michelson Interferometer as ultra stable wavelength reference

    NASA Astrophysics Data System (ADS)

    Wan, Xiaoke; Ge, Jian

    2010-07-01

    Ultra-stable Monolithic Michelson interferometer can be an ideal reference for highprecision applications such as RV measurement in planet searching and orbit study. The advantages include wide wavelength range, simple sinusoidal spectral format, and high optical efficiency. In this paper, we report that a monolithic Michelson interferometers has been in-house developed with minimized thermal sensitivity with compensation tuning. With a scanning white light interferometer, the thermal sensitivity is measured ~ 6x10-7/°C at 550 nm and it decreases to zero near 1000 nm. We expect the wideband wavelength reference source to be stabilized better than 0.3 m/s for RV experiments

  9. EIT Based Gas Detector Design by Using Michelson Interferometer

    SciTech Connect

    Abbasian, K.; Rostami, A.; Abdollahi, M. H.

    2011-12-26

    Electromagnetically induced transparency (EIT) is one of the interesting phenomena of light-matter interaction which modifies matter properties for propagation of light. In other words, we can change the absorption and refractive index (RI) in neighborhood of the resonant frequency using EIT. In this paper, we have doped 3-level quantum dots in one of the Michelson Interferometer's mirror and used EIT to change its RI. So, a controllable phase difference between lights in two arms of interferometer is created. Long response time is the main drawback of Michelson interferometer based sensor, which is resolved by this technique.

  10. Development of CO2 laser dispersion interferometer with photoelastic modulator.

    PubMed

    Akiyama, T; Kawahata, K; Okajima, S; Nakayama, K

    2010-10-01

    A dispersion interferometer is one of the promising methods of the electron density measurement on large and high density fusion devices. This paper describes development of a CO(2) laser dispersion interferometer with a photoelastic modulator for phase modulation. In order to make the dispersion interferometer free from variations of the detected intensity, a new phase extraction method is introduced: The phase shift is evaluated from a ratio of amplitudes of the fundamental and the second harmonics of the phase modulation frequency in the detected interference signal. The proof-of-principle experiments demonstrate the feasibility of this method. PMID:21033856

  11. 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.

  12. Method of calibrating an interferometer and reducing its systematic noise

    NASA Technical Reports Server (NTRS)

    Hammer, Philip D. (Inventor)

    1997-01-01

    Methods of operation and data analysis for an interferometer so as to eliminate the errors contributed by non-responsive or unstable pixels, interpixel gain variations that drift over time, and spurious noise that would otherwise degrade the operation of the interferometer are disclosed. The methods provide for either online or post-processing calibration. The methods apply prescribed reversible transformations that exploit the physical properties of interferograms obtained from said interferometer to derive a calibration reference signal for subsequent treatment of said interferograms for interpixel gain variations. A self-consistent approach for treating bad pixels is incorporated into the methods.

  13. High-Resolution Atom Interferometers with Suppressed Diffraction Phases

    NASA Astrophysics Data System (ADS)

    Estey, Brian; Yu, Chenghui; Müller, Holger; Kuan, Pei-Chen; Lan, Shau-Yu

    2015-08-01

    We experimentally and theoretically study the diffraction phase of large-momentum transfer beam splitters in atom interferometers based on Bragg diffraction. We null the diffraction phase and increase the sensitivity of the interferometer by combining Bragg diffraction with Bloch oscillations. We demonstrate agreement between experiment and theory, and a 1500-fold reduction of the diffraction phase, limited by measurement noise. In addition to reduced systematic effects, our interferometer has high contrast with up to 4.4 ×106 radians of phase difference, and a resolution in the fine structure constant of ? ? /? =0.25 ppb in 25 h of integration time.

  14. Large-aperture interferometer using local reference beam

    NASA Technical Reports Server (NTRS)

    Howes, W. L.

    1982-01-01

    A large-aperture interferometer was devised by adding a local-reference-beam-generating optical system to a schlieren system. Two versions of the interferometer are demonstrated, one employing 12.7 cm (5 in.) diameter schlieren optics, the other employing 30.48 cm (12 in.) diameter parabolic mirrors in an off-axis system. In the latter configuration a cylindrical lens is introduced near the light source to correct for astigmatism. A zone plate is a satisfactory decollimating element in the reference-beam arm of the interferometer. Attempts to increase the flux and uniformity of irradiance in the reference beam by using a diffuser are discussed.

  15. 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

  16. POLCAL - POLARIMETRIC RADAR CALIBRATION

    NASA Technical Reports Server (NTRS)

    Vanzyl, J.

    1994-01-01

    Calibration of polarimetric radar systems is a field of research in which great progress has been made over the last few years. POLCAL (Polarimetric Radar Calibration) is a software tool intended to assist in the calibration of Synthetic Aperture Radar (SAR) systems. In particular, POLCAL calibrates Stokes matrix format data produced as the standard product by the NASA/Jet Propulsion Laboratory (JPL) airborne imaging synthetic aperture radar (AIRSAR). POLCAL was designed to be used in conjunction with data collected by the NASA/JPL AIRSAR system. AIRSAR is a multifrequency (6 cm, 24 cm, and 68 cm wavelength), fully polarimetric SAR system which produces 12 x 12 km imagery at 10 m resolution. AIRSTAR was designed as a testbed for NASA's Spaceborne Imaging Radar program. While the images produced after 1991 are thought to be calibrated (phase calibrated, cross-talk removed, channel imbalance removed, and absolutely calibrated), POLCAL can and should still be used to check the accuracy of the calibration and to correct it if necessary. Version 4.0 of POLCAL is an upgrade of POLCAL version 2.0 released to AIRSAR investigators in June, 1990. New options in version 4.0 include automatic absolute calibration of 89/90 data, distributed target analysis, calibration of nearby scenes with calibration parameters from a scene with corner reflectors, altitude or roll angle corrections, and calibration of errors introduced by known topography. Many sources of error can lead to false conclusions about the nature of scatterers on the surface. Errors in the phase relationship between polarization channels result in incorrect synthesis of polarization states. Cross-talk, caused by imperfections in the radar antenna itself, can also lead to error. POLCAL reduces cross-talk and corrects phase calibration without the use of ground calibration equipment. Removing the antenna patterns during SAR processing also forms a very important part of the calibration of SAR data. Errors in the processing altitude or in the aircraft roll angle are possible causes of error in computing the antenna patterns inside the processor. POLCAL uses an altitude error correction algorithm to correctly remove the antenna pattern from the SAR images. POLCAL also uses a topographic calibration algorithm to reduce calibration errors resulting from ground topography. By utilizing the backscatter measurements from either the corner reflectors or a well-known distributed target, POLCAL can correct the residual amplitude offsets in the various polarization channels and correct for the absolute gain of the radar system. POLCAL also gives the user the option of calibrating a scene using the calibration data from a nearby site. This allows precise calibration of all the scenes acquired on a flight line where corner reflectors were present. Construction and positioning of corner reflectors is covered extensively in the program documentation. In an effort to keep the POLCAL code as transportable as possible, the authors eliminated all interactions with a graphics display system. For this reason, it is assumed that users will have their own software for doing the following: (1) synthesize an image using HH or VV polarization, (2) display the synthesized image on any display device, and (3) read the pixel locations of the corner reflectors from the image. The only inputs used by the software (in addition to the input Stokes matrix data file) is a small data file with the corner reflector information. POLCAL is written in FORTRAN 77 for use on Sun series computers running SunOS and DEC VAX computers running VMS. It requires 4Mb of RAM under SunOS and 3.7Mb of RAM under VMS for execution. The standard distribution medium for POLCAL is a .25 inch streaming magnetic tape cartridge in UNIX tar format. It is also available on a 9-track 1600 BPI magnetic tape in DEC VAX FILES-11 format or on a TK50 tape cartridge in DEC VAX FILES-11 format. Other distribution media may be available upon request. Documentation is included in the price of the program. POLCAL 4.0 was released in 1992 and is a copyrighted work with all copyright vested in NASA.

  17. Radar Imaging of Asteroids

    NASA Astrophysics Data System (ADS)

    Ostro, S. J.

    1996-09-01

    Measurements of the distribution of echo power in time delay (range) and Doppler frequency (line-of-sight velocity) can synthesize images of near-Earth and main-belt asteroids (NEAs and MBAs) that traverse the detectability windows of groundbased radar telescopes. Under ideal circumstances, current radar waveforms can achieve decameter surface resolution. The number of useful pixels obtainable in an imaging data set is of the same order as the signal-to-noise ratio, SNR, of an optimally filtered, weighted sum of all the data. (SNR increases as the square root of the integration time.) The upgraded Arecibo telescope which is about to become operational, should be able to achieve single-date SNRs {\\underline>} (20,100) for an average of (35,5) MBAs per year and single-date SNRs {\\underline>} (20,100,1000) for an average of (10,6,2) of the currently catalogued NEAs per year; optical surveying of the NEA population could increase the frequency of opportunities by an order of magnitude. The strongest imaging opportunities predicted for Arecibo between now and the end of 1997 include (the peak SNR/date is in parentheses): 9 Metis (110), 27 Euterpe (170), 80 Sappho (100), 139 Juewa (140), 144 Vibilia (140), 253 Mathilde (100), 2102 Tantalus (570), 3671 Dionysus (170), 3908 1980PA (4400), 4179 Toutatis (16000), 4197 1982TA (1200), 1991VK (700), and 1994PC1 (7400). A delay-Doppler image projects the echo power distribution onto the target's apparent equatorial plane. One cannot know a priori whether one or two (or more) points on the asteroid contributed power to a given pixel, so accurate interpretation of delay-Doppler images requires modeling (Hudson, 1993, Remote Sensing Rev. 8, 195-203). Inversion of an imaging sequence with enough orientational coverage can remove "north/south" ambiguities and can provide estimates of the target's three-dimensional shape, spin state, radar scattering properties, and delay-Doppler trajectory (e.g., Ostro et al. 1995, Science 270, 80-83; Hudson and Ostro 1995, Science 270, 84-86).

  18. A Bistatic Parasitical Radar (BIPAR)

    NASA Astrophysics Data System (ADS)

    Hartl, Philipp; Braun, Hans Martin

    1989-01-01

    After decades of remote sensing from aircraft and satellites with cameras and other optical sensors, earth observation by imaging radars becomes more and more suitable because of their night and day and all weather operations capability and their information content being complementary to those of optical sensors. The major problem with microwave sensors (radars) is that there are not enough of them presently in operation and therefore not enough data available for effective radar signature research for civil applications. It is shown that airborne bistatic real aperture radar receivers can be operated with spaceborne transmitters of opportunity. Famous candidates for those systems are high power communications or direct TV satellites illuminating the earth surface with a power denisty of more than 10(-12) Watt/sq meter. The high sophisticated status of signal processing technology today allows the realization of receivers correlating the received direct path signal from a communications satellite with its avoidable reflection on the ground. Coherent integration can improve the signal to noise ratio up to values where the radiometric resolution can satisfy users needs. The development of such parasitic radar receivers could even provide a cost effective way to open up new frequency bands for radar signature research. Advantages of these quiet systems for the purpose of classical radar reconnaissance are evident.

  19. Interception of LPI radar signals

    NASA Astrophysics Data System (ADS)

    Lee, Jim P.

    1991-11-01

    Most current radars are designed to transmit short duration pulses with relatively high peak power. These radars can be detected easily by the use of relatively modest EW intercept receivers. Three radar functions (search, anti-ship missile (ASM) seeker, and navigation) are examined to evaluate the effectiveness of potential low probability of intercept (LPI) techniques, such as waveform coding, antenna profile control, and power management that a radar may employ against current Electronic Warfare (EW) receivers. The general conclusion is that it is possible to design a LPI radar which is effective against current intercept EW receivers. LPI operation is most easily achieved at close ranges and against a target with a large radar cross section. The general system sensitivity requirement for the detection of current and projected LPI radars is found to be on the order of -100 dBmi which cannot be met by current EW receivers. Finally, three potential LPI receiver architectures, using channelized, superhet, and acousto-optic receivers with narrow RF and video bandwidths are discussed. They have shown some potential in terms of providing the sensitivity and capability in an environment where both conventional and LPI signals are present.

  20. 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.

  1. Reducing the interference between sidelobe cancellers and sidelobe blankers in electronic scanning array radars

    NASA Astrophysics Data System (ADS)

    Chin, J. E.; Liebman, P. M.; Fleming, J. E.

    The interferometer effects that result from combining SLB (sidelobe blanker) and SLC (sidelobe canceller) auxiliary antennas threaten the compatibility of the two functions within a single radar system. An investigation of techniques to reduce or eliminate these effects is presented. Descriptions are presented of the simulation models (which consisted of planar arrays and cylindrical arrays), analytical approach, and results of the study. The results from early tests of two techniques-namely, aperture switching and jammer assignment or beam switching of steerable auxiliaries on a pulse-to-pulse basis during the duration of a pulse burst-unmistakably indicate that the interference effects can be reduced.

  2. Radar, Insect Population Ecology, and Pest Management

    NASA Technical Reports Server (NTRS)

    Vaughn, C. R. (Editor); Wolf, W. (Editor); Klassen, W. (Editor)

    1979-01-01

    Discussions included: (1) the potential role of radar in insect ecology studies and pest management; (2) the potential role of radar in correlating atmospheric phenomena with insect movement; (3) the present and future radar systems; (4) program objectives required to adapt radar to insect ecology studies and pest management; and (5) the specific action items to achieve the objectives.

  3. 47 CFR 80.273 - Radar standards.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Radar standards. 80.273 Section 80.273... MARITIME SERVICES Equipment Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar... with radar must comply with the following standards (all incorporated by reference, see § 80.7):...

  4. 46 CFR 121.404 - Radars.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 4 2012-10-01 2012-10-01 false Radars. 121.404 Section 121.404 Shipping COAST GUARD... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph (b) of this section, all self... radar system for surface navigation with a radar screen mounted at the primary operating station....

  5. 46 CFR 121.404 - Radars.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Radars. 121.404 Section 121.404 Shipping COAST GUARD... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph (b) of this section, all self... radar system for surface navigation with a radar screen mounted at the primary operating station....

  6. 47 CFR 80.273 - Radar standards.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Radar standards. 80.273 Section 80.273... MARITIME SERVICES Equipment Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar... with radar must comply with the following standards (all incorporated by reference, see § 80.7):...

  7. 47 CFR 80.273 - Radar standards.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Radar standards. 80.273 Section 80.273... MARITIME SERVICES Equipment Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar... with radar must comply with the following standards (all incorporated by reference, see § 80.7):...

  8. FIRE_CI2_ETL_RADAR

    Atmospheric Science Data Center

    2015-11-25

    FIRE_CI2_ETL_RADAR Project Title:  FIRE II CIRRUS Discipline:  ... Platform:  Ground Station Instrument:  Radar Spatial Coverage:  (37.06, -95.34) Spatial ... Search Guide Documents:  ETL_RADAR Guide Readme Files:  Readme ETL_RADAR (PS) ...

  9. 46 CFR 121.404 - Radars.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Radars. 121.404 Section 121.404 Shipping COAST GUARD... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph (b) of this section, all self... radar system for surface navigation with a radar screen mounted at the primary operating station....

  10. 46 CFR 121.404 - Radars.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Radars. 121.404 Section 121.404 Shipping COAST GUARD... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph (b) of this section, all self... radar system for surface navigation with a radar screen mounted at the primary operating station....

  11. 46 CFR 121.404 - Radars.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Radars. 121.404 Section 121.404 Shipping COAST GUARD... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph (b) of this section, all self... radar system for surface navigation with a radar screen mounted at the primary operating station....

  12. Single-pass memory system evaluation for multiprogramming workloads

    NASA Technical Reports Server (NTRS)

    Conte, Thomas M.; Hwu, Wen-Mei W.

    1990-01-01

    Modern memory systems are composed of levels of cache memories, a virtual memory system, and a backing store. Varying more than a few design parameters and measuring the performance of such systems has traditionally be constrained by the high cost of simulation. Models of cache performance recently introduced reduce the cost simulation but at the expense of accuracy of performance prediction. Stack-based methods predict performance accurately using one pass over the trace for all cache sizes, but these techniques have been limited to fully-associative organizations. This paper presents a stack-based method of evaluating the performance of cache memories using a recurrence/conflict model for the miss ratio. Unlike previous work, the performance of realistic cache designs, such as direct-mapped caches, are predicted by the method. The method also includes a new approach to the problem of the effects of multiprogramming. This new technique separates the characteristics of the individual program from that of the workload. The recurrence/conflict method is shown to be practical, general, and powerful by comparing its performance to that of a popular traditional cache simulator. The authors expect that the availability of such a tool will have a large impact on future architectural studies of memory systems.

  13. 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

  14. Hanford Single-Pass Reactor Fuel Storage Basin Demolition.

    PubMed

    Armstrong, Jason A.

    2003-02-01

    ABSTRACT 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:12555029

  15. Single pass Doppler positioning for Search and Rescue satellite missions

    NASA Technical Reports Server (NTRS)

    Schmid, P. E.; Vonbun, F. O.; Lynn, J. J.

    1976-01-01

    This paper describes the implementation of beacon location experiments involving the NASA Nimbus-6 and the Amateur Satellite Corporation (AMSAT) Oscar-6 and Oscar-7 spacecraft. The purpose of these experiments is to demonstrate the feasibility of determining the geographical location of a low power VHF 'distress beacon' via satellite. Doppler data collected during satellite passes is reduced in a mini-computer by means of a simple algorithm resulting in the simultaneous recovery of the unknown receiver coordinates and the unknown Doppler bias frequency. Results indicate point positioning to within a few kilometers - which is within the required accuracies for the positioning of downed aircraft for Search/Rescue missions.

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

    SciTech Connect

    Byrd, J.M.; Thomson, J.; Chao, A.W.; Heifets, S.; Minty, M.G.; Seeman, J.T.; Stupakov, G.V.; Zimmermann, F.; 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.

  17. Ganymede: observations by radar.

    PubMed

    Goldstein, R M; Morris, G A

    1975-06-20

    Radar cross-section measurements indicate that Ganymede scatters to Earth 12 percent of the power expected from a conducting sphere of the same size and distance. This compares with 8 percent for Mars, 12 percent for Venus, 6 percent for Mercury, and about 8 percent for the asteroid Toro. Furthermore, Ganymede is considerably rougher (to the scale of the wavelength used, 12.6 centimeters) than Mars, Venus, or Mercury. Roughness is made evident in this experiment by the presence of echoes away from the center of the disk. A perfectly smooth target would reflect only a glint from the center, whereas a very rough target would reflect power from over the entire disk. PMID:17818164

  18. Multistatic radar resource management

    NASA Astrophysics Data System (ADS)

    Horridge, Paul R.; Hernandez, Marcel L.

    2003-12-01

    In this paper, we implement a previously developed sensor management framework within the domain of multistatic radar resource management. The methodology is based on controlling the Posterior Cram³er-Rao Lower Bound (PCRLB) which provides a bound on the performance of any unbiased target state estimator. In the second part of the paper, the additional complication of the Doppler Blind Zone, inside which the target cannot be detected, is considered. In the case of missed detections, the PCRLB has been shown to be overly optimistic, so we use a performance measure which more accurately accounts for missed detections. However, existing measures fail to accommodate constraints arising from the blind zone, so we modify the measure to incorporate this extra information. The modified measure is shown to give a more accurate estimate of tracking performance, facilitating efficient resource management.

  19. Multistatic radar resource management

    NASA Astrophysics Data System (ADS)

    Horridge, Paul R.; Hernandez, Marcel L.

    2004-01-01

    In this paper, we implement a previously developed sensor management framework within the domain of multistatic radar resource management. The methodology is based on controlling the Posterior Cra?er-Rao Lower Bound (PCRLB) which provides a bound on the performance of any unbiased target state estimator. In the second part of the paper, the additional complication of the Doppler Blind Zone, inside which the target cannot be detected, is considered. In the case of missed detections, the PCRLB has been shown to be overly optimistic, so we use a performance measure which more accurately accounts for missed detections. However, existing measures fail to accommodate constraints arising from the blind zone, so we modify the measure to incorporate this extra information. The modified measure is shown to give a more accurate estimate of tracking performance, facilitating efficient resource management.

  20. "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

  1. Radar images of Mars.

    PubMed

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

    1991-09-27

    Full disk images of Mars have been obtained with the use of the Very Large Array (VLA) to map the radar reflected flux density. The transmitter system was the 70-m antenna of the Deep Space Network at Goldstone, California. The surface of Mars was illuminated with continuous wave radiation at a wavelength of 3,5 cm. The reflected energy was mapped in individual 12-minute snapshots with the VLA in its largest configuration; fringe spacings as small as 67 km were obtained. The images reveal near-surface features including a region in the Tharsis volcano area, over 2000 km in east-west extent, that displayed no echo to the very low level of the radar system noise. The feature, called Stealth, is interpreted as a deposit of dust or ash with a density less than about 0.5 gram per cubic centimeter and free of rocks larger than 1 cm across. The deposit must be several meters thick and may be much deeper. The strongest reflecting geological feature was the south polar ice cap, which was reduced in size to the residual south polar ice cap at the season of observation. The cap image is interpreted as arising from nearly pure CO(2) or H(2)O ice with a small amount of martian dust (less than 2 percent by volume) and a depth greater than 2 to 5 m. Only one anomalous reflecting feature was identified outside of the Tharsis region, although the Elysium region was poorly sampled in this experiment and the north pole was not visible from Earth. PMID:17784090

  2. 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

  3. 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.

  4. 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.

  5. Automatic Alignment of Displacement-Measuring Interferometer

    NASA Technical Reports Server (NTRS)

    Halverson, Peter; Regehr, Martin; Spero, Robert; Alvarez-Salazar, Oscar; Loya, Frank; Logan, Jennifer

    2006-01-01

    A control system strives to maintain the correct alignment of a laser beam in an interferometer dedicated to measuring the displacement or distance between two fiducial corner-cube reflectors. The correct alignment of the laser beam is parallel to the line between the corner points of the corner-cube reflectors: Any deviation from parallelism changes the length of the optical path between the reflectors, thereby introducing a displacement or distance measurement error. On the basis of the geometrical optics of corner-cube reflectors, the length of the optical path can be shown to be L = L(sub 0)cos theta, where L(sub 0) is the distance between the corner points and theta is the misalignment angle. Therefore, the measurement error is given by DeltaL = L(sub 0)(cos theta - 1). In the usual case in which the misalignment is small, this error can be approximated as DeltaL approximately equal to -L(sub 0)theta sup 2/2. The control system (see figure) is implemented partly in hardware and partly in software. The control system includes three piezoelectric actuators for rapid, fine adjustment of the direction of the laser beam. The voltages applied to the piezoelectric actuators include components designed to scan the beam in a circular pattern so that the beam traces out a narrow cone (60 microradians wide in the initial application) about the direction in which it is nominally aimed. This scan is performed at a frequency (2.5 Hz in the initial application) well below the resonance frequency of any vibration of the interferometer. The laser beam makes a round trip to both corner-cube reflectors and then interferes with the launched beam. The interference is detected on a photodiode. The length of the optical path is measured by a heterodyne technique: A 100- kHz frequency shift between the launched beam and a reference beam imposes, on the detected signal, an interferometric phase shift proportional to the length of the optical path. A phase meter comprising analog filters and specialized digital circuitry converts the phase shift to an indication of displacement, generating a digital signal proportional to the path length.

  6. Stroboscopic Interferometer for Measuring Mirror Vibrations

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip; Robers, Ted

    2005-01-01

    Stroboscopic interferometry is a technique for measuring the modes of vibration of mirrors that are lightweight and, therefore, unavoidably flexible. The technique was conceived especially for modal characterization of lightweight focusing mirror segments to be deployed in outer space; however, the technique can be applied to lightweight mirrors designed for use on Earth as well as the modal investigation of other optical and mechanical structures. To determine the modal structure of vibration of a mirror, it is necessary to excite the mirror by applying a force that varies periodically with time at a controllable frequency. The excitation can utilize sinusoidal, square, triangular, or even asynchronous waveforms. Because vibrational modes occur at specific resonant frequencies, it is necessary to perform synchronous measurements and sweep the frequency to locate the significant resonant modes. For a given mode it is possible to step the phase of data acquisition in order to capture the modal behavior over a single cycle of the resonant frequency. In order to measure interferometrically the vibrational response of the mirror at a given frequency, an interferometer must be suitably aligned with the mirror and adjustably phase-locked with the excitation signal. As in conventional stroboscopic photography, the basic idea in stroboscopic interferometry is to capture an image of the shape of a moving object (in this case, the vibrating mirror) at a specified instant of time in the vibration cycle. Adjusting the phase difference over a full cycle causes the interference fringes to vary over the full range of motion for the mode at the excitation frequency. The interference-fringe pattern is recorded as a function of the phase difference, and, from the resulting data, the surface shape of the mirror for the given mode is extracted. In addition to the interferometer and the mirror to be tested, the equipment needed for stroboscopic interferometry includes an arbitrary-function generator (that is, a signal generator), an oscilloscope, a trigger filter, and an advanced charge-coupled-device (CCD) camera. The optical components are positioned to form a pupil image of the mirror under test on the CCD chip, so that the interference pattern representative of the instantaneous mirror shape is imaged on the CCD chip.

  7. 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.

  8. Coupled-Cavity Interferometer for the Optics Laboratory

    ERIC Educational Resources Information Center

    Peterson, R. W.

    1975-01-01

    Describes the construction of a flexible coupled-cavity interferometer for student use. A helium-neon laser and phonograph turntable are the main components. Lists activities which may be performed with the apparatus. (Author/CP)

  9. Increasing the Sensitivity of the Michelson Interferometer through Multiple Reflection

    NASA Astrophysics Data System (ADS)

    Youn, Woonghee

    Michelson interferometry has been one of the most famous and popular optical interference system for analyzing optical components and measuring optical metrology properties. Typical Michelson interferometer can measure object displacement with wavefront shapes to one half of the laser wavelength. As testing components and devices size reduce to micro and nano dimension, Michelson interferometer sensitivity is not suitable. The purpose of this study is to design and develop the Michelson interferometer using the concept of multiple reflections. This thesis proposes a new and novel design for a multiple reflection interferometer, where the number of reflections does not affect the quality of the interference. Theoretically we show that more than 1000 reflections can be achieved. Experimental results of greater than 100 reflections are presented in this thesis.

  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. Analysis Of An In-Line Object Beam Hologram Interferometer

    NASA Astrophysics Data System (ADS)

    Celaya, Martin; Tentori, Diana; Villagomez, Ricardo

    1988-01-01

    The performance characteristics of an In-line Object Beam Hologram Interferometer working with a diffuse object are analyzed. This analysis considers two criteria optical path difference and the correlation of homologous points at the image plane.

  12. 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.

  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. Large-momentum-transfer Bragg interferometer with strontium atoms

    NASA Astrophysics Data System (ADS)

    Mazzoni, T.; Zhang, X.; Del Aguila, R.; Salvi, L.; Poli, N.; Tino, G. M.

    2015-11-01

    We report on an atom interferometer based on Bragg diffraction in a fountain of alkaline-earth-metal atoms, namely 88Sr. We demonstrate large momentum transfer to the atoms up to eight photon recoils and the use of the interferometer as a gravimeter with a sensitivity ? g /g =4 ×10-8 . Thanks to the special characteristics of strontium atoms for precision measurements, this result introduces alternate possibilities for experiments in fundamental and applied physics.

  15. Polarization Considerations for the Laser Interferometer Space Antenna (LISA)

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Pedersen, Trace R.; McNamara, Paul

    2005-01-01

    A polarization ray trace model of the Laser Interferometer Space Antenna's (LISA) optical path is being created. The model will be able to assess the effects of various polarizing elements and the optical coatings on the required picometer level interferometry. All of the computational steps are described in detail. This should eliminate any ambiguities associated with polarization ray trace modeling of interferometers and provide a basis for determining its limitations and serve as a clearly defined starting point for future improvements.

  16. Comment on ''Rovibrational quantum interferometers and gravitational waves''

    SciTech Connect

    Khriplovich, I. B.; Lamoreaux, S. K.; Sushkov, A. O.; Sushkov, O. P.

    2010-06-15

    In a recent paper, Wicht, Laemmerzahl, Lorek, and Dittus [Phys. Rev. A 78, 013610 (2008)] come to the conclusion that a molecular rotational-vibrational quantum interferometer may possess the sensitivity necessary to detect gravitational waves. We do not agree with their results and demonstrate here that the true sensitivity of such an interferometer is many orders of magnitude worse than that claimed in the paper.

  17. Fiber Fabry-Perot interferometer with controllable temperature sensitivity.

    PubMed

    Zhang, Xinpu; Peng, Wei; Zhang, Yang

    2015-12-01

    We proposed a fiber taper based on the Fabry-Perot (FP) interferometer structure with controllable temperature sensitivity. The FP interferometer is formed by inserting a segment of tapered fiber tip into the capillary and subsequently splicing the other end of the capillary to a single-mode fiber (SMF), the tapered fiber endface, and the spliced face form the FP cavity. Through controlling the inserted tapered fiber length, a series of FP interferometers were made. Because the inserted taper tip has the degree of freedom along the fiber axial, when the FP interferometer is subjected to temperature variation, the thermal expansion of the fiber taper tip will resist the FP cavity length change caused by the evolution of capillary length, and we can control the temperature sensitivity by adjusting the inserted taper length. In this structure, the equivalent thermal expansion coefficient of the FP interferometer can be defined; it was used to evaluate the temperature sensitivity of the FP interferometer, which provides an effective method to eliminate the temperature effect and to enhance other measurement accuracy. We fabricated the FP interferometers and calibrated their temperature characters by measuring the wavelength shift of the resonance dips in the reflection spectrum. In a temperature range of 50°C to 150°C, the corresponding temperature sensitivities can be controlled between 0 and 1.97 pm/°C when the inserted taper is between 75 and 160 μm. Because of its controllable temperature sensitivity, ease of fabrication, and low cost, this FP interferometer can meet different temperature sensitivity requirements in various application areas, especially in the fields which need temperature insensitivity. PMID:26625075

  18. A Dual-Condensate Interferometer for Vibration-Free Measurements

    NASA Astrophysics Data System (ADS)

    Leonard, R. H.; Horne, R. A.; Sackett, C. A.

    2011-05-01

    A generic problem with atom interferometry is a high sensitivity to vibrational noise. In particular, the low frequency vibrations associated with building, traffic, and seismic activity can be very difficult to isolate, and can limit the usable measurement time of the interferometer. An alternative solution is to simultaneously implement two interferometers in the same apparatus, such that the vibrational noise is common mode but the signal to be measured is not. The difference in phase measured between the two interferometers then provides a signal measurement that is independent of the noise. This technique has previously been implemented effectively using non-condensed atoms for gravity gradiometry and rotational sensing. We present here a dual-interferometer scheme based on Bose-Einstein condensates confined in a linear magnetic guide. With only conventional vibration isolation, the coherence time of the interferometer is limited to about 70 ms, whereas (noisy) interference has been observed for up to 1 s. Current experimental results from the dual interferometer scheme will be presented, along with techniques for applying the scheme to various types of measurement.

  19. The optimal design method for the extended source of interferometer

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The optimal design for an extended source interferometer is discussed in this paper. Compared with the classical point source interferometer, interferometer with an extended source can decrease the coherent noise, dust/defects scattering effects and high-frequency error of reference surface significantly. The adjustable extended source model is introduced. The size, shape, and intensity distribution of the source are optimized by using the interferometer simulation platform which is established by Zemax optical design software and Matlab data analysis software in this paper. After determined parameters of the basic structure of the interferometer, an interferometer model was set up by using muti-configuration in the sequential mode of Zemax. The communication technique of DDE (Dynamic Data Exchange) between Zemax and Matlab was applied to the numeric simulation process. Under the control of Matlab, the field parameters of the optical system can be rectified, and it was easy to get a series of interferogram data. So it was convenient to calculate the visibility of interference fringes. The relation curves between the spatial coherence and the size, shape, intensity distribution of the extended source can be plotted by Matlab. In order to meet the operating requirements of different coherence lengths, Zemax was used to optimize the concrete forms of light sources. Simulation results show that short coherence length can be realized by the Sinc2—shaped extended source, while source of Cos—shape or Comb—shape can realize long coherence length.

  20. Experimental implementation of phase locking in a nonlinear interferometer

    NASA Astrophysics Data System (ADS)

    Wang, Hailong; Marino, A. M.; Jing, Jietai

    2015-09-01

    Based upon two cascade four-wave mixing processes in two identical hot rubidium vapor cells, a nonlinear interferometer has been experimentally realized [Jing et al., Appl. Phys. Lett. 99, 011110 (2011); Hudelist et al., Nat. Commun. 5, 3049 (2014)]. It has a higher degree of phase sensitivity than a traditional linear interferometer and has many potential applications in quantum metrology. Phase locking of the nonlinear interferometer is needed before it can find its way into applications. In this letter, we investigate the experimental implementation of phase locking of the relative phase between the three beams at different frequencies involved in such a nonlinear interferometer. We have utilized two different methods, namely, beat note locking and coherent modulation locking. We find that coherent modulation locking can achieve much better phase stability than beat note locking in our system. Our results pave the way for real applications of a nonlinear interferometer in precision measurement and quantum manipulation, for example, phase control in phase-sensitive N-wave mixing process, N-port nonlinear interferometer and quantum-enhanced real-time phase tracking.