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1

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

2

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

NASA Astrophysics Data System (ADS)

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.

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

3

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

NASA Technical Reports Server (NTRS)

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.

Thurman, S. W.

1990-01-01

4

Synthetic interferometer radar for topographic mapping  

Microsoft Academic Search

The production of topographic maps requires two kinds of information. First, the detail to be placed on the map sheet must be identified. Second, the positions of the various objects and features must be measured in three dimensions. Current airborne radar technology provides the means to satisfy both of these requirements in adverse weather and at any time, day or

L. C. Graham

1974-01-01

5

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

NASA Astrophysics Data System (ADS)

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.

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

6

The Shuttle Radar Topography Mission  

Microsoft Academic Search

The Shuttle Radar Topography Mission (SRTM), which flew successfully aboard Endeavour in February 2000, is a cooperative project between NASA and the National Imagery and Mapping Agency (NIMA). The mission was 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 56 degrees south latitude. The

T. G. Farr; M. Kobrick

2001-01-01

7

Radar Interferometer for Topographic Mapping of Glaciers and Ice Sheets  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

8

The Shuttle Radar Topography Mission: Introduction to Special Session  

Microsoft Academic Search

The Shuttle Radar Topography Mission (SRTM), which flew successfully aboard Endeavour in February 2000, is a cooperative project between NASA, the National Imagery and Mapping Agency, and the German and Italian Space Agencies. The mission was designed to use a single-pass radar interferometer to produce a digital elevation model of the Earth's land surface between about 60^o north and 56^o

T. G. Farr; M. Werner; M. Kobrick

2003-01-01

9

Multifrequency, single pass free electron laser  

DOEpatents

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.

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

1985-01-01

10

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

11

Dilution in single pass arc welds  

SciTech Connect

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.

DuPont, J.N.; Marder, A.R. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science and Engineering

1996-06-01

12

Terrestrial Radar Interferometer Observations of a Rapid Landslide Over Vegetated Terrain  

NASA Astrophysics Data System (ADS)

In the Spring of 2013 a landslide in the Hintergraben region of canton Obwalden in Switzerland showed a rapid increase in velocity. Hintergraben, at an elevation of about 900 meters is characterized by meadow and some trees. A region approximately 200 meters wide and 500 meters long was affected. Starting in February, the velocity increased to 30 cm/day by 1-May and continued to accelerate by deceleration to 8 cm/day by 27-May. We report on observations of this landslide using the Gamma Portable Radar Interferometer (GPRI). The GPRI is an FM-CW radar operating at 17.2 GHz (Ku-Band) with an operational range up to 10 km. Range resolution is 90 cm along the LOS. The instrument operates in real-aperture mode with 0.4 degree wide fan-beam giving an azimuth resolution better than 7 meters at 1 kilometer range. During data acquisition, the radar performed an azimuth scan of the scene at a rate of 5 degrees/sec. The radar is phase coherent and capable of acquiring data suitable for differential interferometry with a precision for measuring changes in the LOS distance > 0.1 mm. Limiting factors in the accuracy of LOS motion are interferometric phase coherence and variations in delay due to water vapor. The GPRI was deployed to map ground motion for 2 campaigns on 6 May and 26-27 May 2013. The radar position over 3.5 km from the landslide on the opposite side of Lake Sarnen. Due to rapid temporal decorrelation at Ku-Band data, acquisitions were made at 1 minute intervals. The GPRI deformation maps cover almost the entire region of the active landslide during both observation periods of 6 hours on 6 May and 9 hours on 26-27 May. Measured peak velocities were 35 and 8 cm/day respectively. Point-wise verification of the radar observations was carried out using a Leica TCR803 total station with an estimated accuracy of 1/2 mm at 3.5 km distance. A set of optical corner cubes and radar reflectors were set up in the region of the landslide on 26-May. The radar deformation measurements are within 1/2 mm of the values derived using the total station. Operating the GPRI with 1 minute intervals between successive scans permitted making accurate maps of deformation with millimeter level accuracy over meadow and permitted reconstruction of complete deformation time series. Hitergraben deformation map measured with the GPRI for 6-May 2013. Contours are in cm/day along the LOS.

Werner, C. L.; Caduff, R.; Strozzi, T.; Wegmüller, U.

2013-12-01

13

Single Pass Multi-component Harvester  

SciTech Connect

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.

Reed Hoskinson; J. Richard Hess

2004-08-01

14

The Single Pass Multi-component Harvester  

SciTech Connect

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.

Reed Hoskinson; John R. Hess

2004-08-01

15

Efficient Single-Pass Index Construction for Text Databases.  

ERIC Educational Resources Information Center

Discusses index construction for text collections, reviews principal approaches to inverted indexes, analyzes their theoretical cost, and presents experimental results of the use of a single-pass inversion method on Web document collections. Shows that the single-pass approach is faster and does not require the complete vocabulary of the indexed…

Heinz, Steffen; Zobel, Justin

2003-01-01

16

The Shuttle Radar Topography Mission  

NASA Technical Reports Server (NTRS)

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.

Farr, Tom G.; Kobrick, Mike

2000-01-01

17

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

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

18

The Shuttle Radar Topography Mission: A Global DEM  

NASA Technical Reports Server (NTRS)

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.

Farr, Tom G.; Kobrick, Mike

2000-01-01

19

Experimental demonstration of frequency pulling in single-pass free-electron lasers.  

PubMed

Frequency pulling is a well-known phenomenon in standard laser physics, leading to a shift of the laser frequency when the cavity and maximum gain frequencies are detuned. In this letter we present the first experimental demonstration of frequency pulling in single-pass free-electron lasers. Measurements are performed using the single-pass free-electron laser installed on the Elettra storage ring. PMID:21643316

Allaria, E; De Ninno, G; Spezzani, C

2011-05-23

20

Practical aspects of single-pass scan Kelvin probe force microscopy  

NASA Astrophysics Data System (ADS)

The single-pass scan Kelvin probe force microscopy (KPFM) in ambient condition has a few advantages over the dual-pass lift-up scan KPFM. For example, its spatial resolution is expected to be higher; and its topographical errors caused by electrostatic forces are minimized because electrostatic forces are actively suppressed during the simultaneous topographical and KPFM measurement. Because single-pass scan KPFM in ambient condition is relatively new, it received little attention in the literature so far. In this article, we discuss several major practical aspects of single-pass scan KPFM especially in ambient condition. First, we define the resolution using a point spread function. With this definition, we analyze the relation between the resolution and the scanning parameters such as tip apex radius and tip-surface distance. We further study the accuracy of KPFM based on the point spread function. Then, we analyze the sensitivity of KPFM under different operation modes. Finally, we investigate the crosstalk between the topographical image and the surface potential image and demonstrate the practical ways to minimize the crosstalk. These discussions not only help us to understand the single-pass scan KPFM but also provide practical guidance in using single-pass scan KPFM.

Li, Guangyong; Mao, Bin; Lan, Fei; Liu, Liming

2012-11-01

21

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)

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.

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

2012-12-01

22

Ground-based portable radar interferometer for imaging glacier flow, ocean-glacier ice interactions, and river ice breakup  

NASA Astrophysics Data System (ADS)

Over the last 18 months we have deployed new 17 GHz imaging radars from Gamma Remote Sensing to document flow on land terminating and tidewater glaciers in Greenland and Alaska; to image glacier response to tides and calving; to track floating ice in fjords; and to document river ice movement, ice jams, and associated flooding during breakup on the Tanana River in Alaska. During these deployments we have learned much about atmospheric influences on interferometric measurements; combination of flow direction determinations from feature tracking in amplitude imagery with short-term flow variability from interferometry. We show examples documenting measurement capabilities and limitations from each of these deployments. These radars represent unique tools for study of rapid changes in dynamic parts of the cryosphere.

Fahnestock, M. A.; Cassotto, R.; Truffer, M.

2013-12-01

23

An Efficient Single-Pass Trace Compression Technique Utilizing Instruction Streams  

E-print Network

An Efficient Single-Pass Trace Compression Technique Utilizing Instruction Streams ALEKSANDAR of new ideas and design prototypes. Efficient trace compression and fast decompression are crucial-gzip compression ratio is from 80 to 35,595, and the SBC-bzip2 compression ratio is from 75 to 191,257. Moreover

Milenkovi, Aleksandar

24

Possibilities of Development in the Single-Pass Internal Cylindrical Grinding  

Microsoft Academic Search

The paper presents trends in the development in the single-pass internal cylindrical grinding worked out in the Department of Production Engineering, Koszalin University of Technology. The role of the computer modeling and simulation in creation of new abrasive tools using the grinding wheels of zoned diversified structure as an example was discussed. The techniques of introducing the artificial porosity into

Krzysztof Nadolny; J. Plichta

2008-01-01

25

Truth Discovery in Data Streams: A Single-Pass Probabilistic Approach  

E-print Network

Truth Discovery in Data Streams: A Single-Pass Probabilistic Approach Zhou Zhao, James Cheng}@cse.ust.hk, jcheng@cse.cuhk.edu.hk ABSTRACT Truth discovery is a long-standing problem for assessing the va- lidity and stock price prediction, effective techniques for truth discovery in data streams are demanded. However

Ng, Wilfred Siu Hung

26

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

SciTech Connect

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.

Gydesen, S.P.

1993-07-01

27

Investigation of catalysts based on activated aluminum oxide, prepared by single-pass continuous precipitation  

Microsoft Academic Search

The properties of an activated aluminum oxide obtained by continuous single-pass precipitation of the hydroxide from solutions of basic aluminum sulfate and sodium aluminate with a low alkali modulus have been studied by physicochemicalmethods; this study has shown that the crystalline and porous structure of this aluminum oxide differs considerably from that of aluminum oxide obtained by a double-pass batch

N. P. Poezd; I. Ya. Perezhigina; E. D. Radchenko; D. F. Poezd; A. V. Agafonov; A. N. Chagovets

1978-01-01

28

Combining Cluster Sampling with Single Pass Methods for Efficient Sampling Regimen Design  

E-print Network

],[5],[12],[17], set sampling [7],[10],[12], and stratified sampling [14]. These methods differ in which elementsCombining Cluster Sampling with Single Pass Methods for Efficient Sampling Regimen Design Paul D sampling and non-sampling biases. Researchers have devised clever methods for effectively reducing non-sampling

Conte, Thomas M.

29

Determining the 630nm emission altitude using modelling and observations from a tristatic configuration of Fabry-Perot Interferometers and EISCAT radars.  

NASA Astrophysics Data System (ADS)

Anasuya Aruliah, a.aruliah@ucl.ac.uk University College London, London, United Kingdom Michael Kosch, m.kosch@lancaster.ac.uk Lancaster University, Lancaster, United Kingdom Tristatic team Anasuya Aruliah,Ho-Ching Iris Yiu,Ian McWhirter, Michael Kosch,Kazuo Shiokawa,Shin-ichiro Oyama,Satonori Nozawa,Vikki Howells,Ian McCrea During early February 2010 a tristatic FPI-EISCAT experiment was run in order to investigate the peak emission altitude of the 630nm airglow and auroral emission in the region of the auroral oval. Two UCL Fabry-Perot Interferometers and a new STEL FPI have been located close to the three EISCAT radars at Tromsø, Kiruna and Sodankylü. The radars were pointed a at a common volume seen by all three FPIs, on assuming a peak emission height of 235km. This altitude is generally assumed to be fairly steady for FPI studies probing the behaviour of the upper atmosphere, though the height is a little different at other latitudes. The smoothing effect of the large viscosity of the upper thermosphere is invoked as a reason why the actual altitude is not too important, and there has been little investigation of the appropriateness of this assumption. However, mesoscale variability in the ionosphere has now been identified as producing a similar quantity of heating as does steady state convection; and FPIs and the CHAMP satellite have shown mesoscale structure in the high-latitude thermosphere. This indicates a need to revisit old assumptions that were based on the premise of thermospheric variability being large-scale. The STEL FPI at Ramfjord has a fully variable pointing direction mechanism and was programmed to point rapidly at successive volumes that would overlap the UCL KEOPS/Kiruna FPI look direction if the emission volume was 195km, 215km, 235km and 255km. Cross-correlation of the temperatures and intensity measurements would then identify the peak emission height. The EISCAT radar provided ionospheric parameters to model the 630nm emission profile for comparison with the FPI observations.

Aruliah, Anasuya; Kosch, Michael

30

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)

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.

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

2013-12-01

31

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

Microsoft Academic Search

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 ?M) at a flow rate of 0.25 ml\\/min. Preliminary binding and stability studies

Thomas J Cook; Smriti S Shenoy

2003-01-01

32

An efficient single-pass trace compression technique utilizing instruction streams  

Microsoft Academic Search

Trace-driven simulations have been widely used in computer architecture for quantitative evaluations of new ideas and design prototypes. Efficient trace compression and fast decompression are crucial for contemporary workloads, as representative benchmarks grow in size and number. This article presents Stream-Based Compression (SBC), a novel technique for single-pass compression of address traces. The SBC technique compresses both instruction and data

Aleksandar Milenkovic; Milena Milenkovic

2007-01-01

33

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

NASA Astrophysics Data System (ADS)

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.

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

2000-07-01

34

A Tandem TerraSAR-X Configuration for Single-Pass SAR Interferometry  

Microsoft Academic Search

TanDEM-X is a mission proposal for a TerraSAR-X add-on satellite to enable high-resolution single-pass SAR interferometry. The TanDEM-X mission has the goal of generating a global Digital Elevation Model (DEM) with an accuracy corresponding to the DTED-3 specifications (12 m posting, 2 m relative height accuracy for flat terrain). This paper describes the mission concept and requirements, including several innovative

Gerhard Krieger; Alberto Moreira; Irena Hajnsek; David Hounam; Marian Werner; Sebastian Riegger; Eckard Settelmeyer

2009-01-01

35

Supersonic COIL driven by centrifugal bubbling SOG with efficient depletion of chemicals in single pass  

NASA Astrophysics Data System (ADS)

An efficient and compact centrifugal bubbling SOG was employed as energy source in supersonic COIL. A centrifugal bubbling SOG generated gas at 100 torr of total pressure providing 90% of chlorine utilization and 60% of O2(1?) yield with efficient depletion of BHP chemicals in single pass through SOG. A 1 kW class ejector COIL powered by this SOG demonstrated a specific power of 12.5 W per 1cm3/s of BHP volumetric rate at chemical efficiency 22.7%.

Zagidullin, Marsel V.; Nikolaev, Valery D.; Khvatov, Nikolay A.; Svistun, Michael I.

2008-10-01

36

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

USGS Publications Warehouse

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.

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

2003-01-01

37

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

NASA Astrophysics Data System (ADS)

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.

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

38

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

39

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

SciTech Connect

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.

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

2005-08-21

40

Single-pass BPM system of the Photon Factory storage ring.  

PubMed

At the 2.5 GeV ring of the Photon Factory, a single-pass beam-position monitor (BPM) system is being prepared for the storage ring and the beam transport line. In the storage ring, the injected beam position during the first several turns can be measured with a single injection pulse. The BPM system has an adequate performance, useful for the commissioning of the new low-emittance lattice. Several stripline BPMs are being installed in the beam transport line. The continuous monitoring of the orbit in the beam transport line will be useful for the stabilization of the injection energy as well as the injection beam orbit. PMID:15263597

Honda, T; Katoh, M; Mitsuhashi, T; Ueda, A; Tadano, M; Kobayashi, Y

1998-05-01

41

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

SciTech Connect

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.

Choudhary, Shashank, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Tejesh, Chiruvolu Mohan, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Regalla, Srinivasa Prakash, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in; Suresh, Kurra, E-mail: shashankbit08@gmail.com, E-mail: mohantejesh93@gmail.com, E-mail: regalla@hyderabad.bits-pilani.ac.in, E-mail: ksuresh@hyderabad.bits-pilani.ac.in [Department of Mechanical Engineering, BITS-Pilani, Hyderabad Campus, Shamirpet, Hyderabad, 500078, Andhra Pradesh (India)

2013-12-16

42

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

43

The MST Radar Technique  

NASA Technical Reports Server (NTRS)

The coherent radar technique is reviewed with special emphasis to mesosphere-stratosphere-troposphere (MST) radars operating in the VHF band. Some basic introduction to Doppler radar measurements and the radar equation is followed by an outline of the characteristics of atmospheric turbulence, viewed from the scattering and reflection processes of radar signals. Radar signal acquisition and preprocessing, namely coherent detection, digital sampling, pre-integration and coding, is briefly discussed. The data analysis is represented in terms of the correlation and spectrum analysis, yielding the essential parameters: power, signal-to-noise ratio, average and fluctuating velocity and persistency. The techniques to measure wind velocities, viz. the different modes of the Doppler method as well as the space antenna method are surveyed and the feasibilities of the MST radar interferometer technique are elucidated. A general view on the criteria to design phased array antennas is given. An outline of the hardware of a typical MST radar system is presented.

Roettger, J.

1984-01-01

44

Effect of Composition on the Formation of Sigma during Single-Pass Welding of Mo-Bearing Stainless Steels  

E-print Network

- tional diffusivity in d-ferrite allows for homogenization during welding even at high cooling rates.[15Effect of Composition on the Formation of Sigma during Single-Pass Welding of Mo-Bearing Stainless, and laser welds were prepared on each alloy at constant power and travel speeds ranging from 4.2 to 42 mm

DuPont, John N.

45

ABSTRACT. Single-pass welds and multi-ple-pass cladding of Fe-Al alloys were  

E-print Network

ABSTRACT. Single-pass welds and multi- ple-pass cladding of Fe-Al alloys were deposited on carbon-temperature (600°C) sulfidation behavior of low-Al alloys (5­10 wt-% Al), which exhibited good weldabilty of dilution levels was achieved that resulted in fusion zone compositions with 3­30 wt-% Al. Under

DuPont, John N.

46

Design of a high gain single stage and single pass Nd:YVO4 passive picosecond amplifier  

E-print Network

); published August 7, 2012 A detailed comparison of the influence of pumping wavelength and crystal doping crystals and the importance of the crystal tem- perature for the design of a high gain amplifier. Using for only 50 mW of seed at 200 kHz in a single pass, single stage configuration. With a pulse duration of 22

47

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

SciTech Connect

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.

Ozawa, Akira; Udem, Thomas; Zeitner, Uwe D.; Haensch, Theodor W.; Hommelhoff, Peter [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Fraunhofer-Institut fuer Angewandte Optik und Feinmechanik IOF, Albert-Einstein-Strasse 7, D-07745 Jena (Germany); Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany)

2010-09-15

48

TanDEM-X: a TerraSAR-X add-on satellite for single-pass SAR interferometry  

Microsoft Academic Search

TanDEM-X is a mission proposal for a TerraSAR-X add-on satellite for high-resolution single-pass SAR interferometry. This mission proposal has been selected for a Phase A study within the scope of a Call for Proposals for a next German Earth Observation Mission to be launched in 2008\\/2009. The mission has the goal of generating a global Digital Elevation Model (DEM) with

Alberto Moreira; Gerhard Krieger; Irena Hajnsek; David Hounam; Marian Werner; Sebastian Riegger; Eckard Settelmeyer

2004-01-01

49

3 dB squeezing by single-pass parametric amplification in a periodically poled KTiOPO4 crystal  

NASA Astrophysics Data System (ADS)

We present the experimental observation of pulsed squeezed light from a degenerate optical parametric amplifier pumped by a second harmonic of a continuous-wave mode-locked Nd:YVO4 laser. With a single pass through a 10 mm long periodically poled KTiOPO4 crystal, the classical parametric gain of 11 is observed. The measured noise reduction in the quiet quadrature is 3.2 dB below the shot-noise level.

Hirano, T.; Kotani, K.; Ishibashi, T.; Okude, S.; Kuwamoto, T.

2005-07-01

50

A Fizeau interferometer system with double-pass and stitching for characterizing the figure error of large (>1m) synchrotron optics  

Microsoft Academic Search

A Fizeau interferometer based system has been developed to measure the figure error of large synchrotron optics using single-pass, double-pass, and stitching geometries. The system, which uses a lambda\\/100 reference flat, is designed to measure optics up to 1.5m in length, and is capable of nanometer level repeatability. Fizeau measurements, in single pass geometry, are conventionally limited to the diameter

G. D. Ludbrook; S. G. Alcock; K. J. S. Sawhney

2009-01-01

51

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

SciTech Connect

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.

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

2005-08-15

52

Single-pass kelvin force microscopy and dC/dZ imaging: applications for graphene-related nanomaterials  

NASA Astrophysics Data System (ADS)

Development of advanced imaging strategies that could either expand the breadth of what is measurable in material science or break the current limits on detection sensitivity and spatial resolution is highly desired for atomic force microscopy (AFM)-associated metrology. We report that single-pass Kelvin force microscopy (KFM) and capacitance gradient (dC/dZ) imaging can be performed in the intermittent contact regime, and it allows simultaneous acquisition of a sample's morphology as well as its two distinctive electric properties with nanometer-scale spatial resolution. Applications of this technique for enhanced sensing of graphene will be presented.

Yu, Jing-jiang; Wu, Shijie

2014-03-01

53

A Low-latency Sub-micron Resolution Stripline Beam Position Monitoring System for Single-pass Beamlines  

E-print Network

A low-latency, sub-micron resolution stripline beam position monitoring system has been developed for use in single-pass beamlines. The fast analogue front-end signal processor is based on a single-stage RF down-mixer and is combined with an FPGA-based system for digitisation and further signal processing. The system has been deployed and tested with beam at the Accelerator Test Facility at KEK. Performance results are presented on the calibration, resolution and stability of the system. A detailed simulation has been developed that is able to account for the measured performance.

Burrows, P N; Kraljevic, N Blaskovic; Christian, G B; Davis, M R; Perry, C; Apsimon, R J; Constance, B; Gerbershagen, A; Resta-Lopez, J

2012-01-01

54

Successes and limitations in imaging glacier and ice cover motion with ground-based radar interferometers - from Greenland outlet systems to a Cascade volcano  

NASA Astrophysics Data System (ADS)

Over the last year we have deployed several Gamma Remote Sensing Ground-based Portable Interferometers (GPRI) to address glaciological research problems in Greenland, Alaska, and the Pacific Northwest. In this talk we outline our successes in imaging the time varying deformation fields in several systems, including Jakobshavns Isbrae and Kangiata Nunata Sermia in western Greenland, Kennecott Glacier and shore-fast sea ice in Alaska, and ice flow on Mt Rainier in the state of Washington. These instruments have performed well in producing line of sight deformation maps in all of these systems, and techniques have been developed to use amplitude image time series from the same instruments to determine ice flow vector direction and to observe propagation of waves through the ice mélange covering the proglacial fjords on two systems. Useful measurements have been made out to a radius of 12 to 16 kilometers. The primary challenge limiting effective measurement of time varying motion in all systems is the impact of atmospheric variability on interferometric measurements over these long distances; techniques for determining and mitigating atmospheric impacts will be discussed.

Fahnestock, M. A.; Cassotto, R. K.; Truffer, M.

2012-12-01

55

A bounding estimate of neutron dose based on measured photon dose around single pass reactors at the Hanford site.  

PubMed

Neutron and photon radiation survey records have been used to evaluate and develop a neutron to photon (NP) ratio to reconstruct neutron doses to workers around Hanford's single pass reactors that operated from 1945 to 1972. A total of 5,773 paired neutron and photon measurements extracted from 57 boxes of survey records were used in the development of the NP ratio. The development of the NP ratio enables the use of the recorded dose from an individual's photon dosimeter badge to be used to estimate the unmonitored neutron dose. The Pearson rank correlation between the neutron and photon measurements was 0.71. The NP ratio best fit a lognormal distribution with a geometric mean (GM) of 0.8, a geometric standard deviation (GSD) of 2.95, and the upper 95 th % of this distribution was 4.75. An estimate of the neutron dose based on this NP ratio is considered bounding due to evidence that up to 70% of the total photon exposure received by workers around the single pass reactors occurs during shutdown maintenance and refueling activities when there is no significant neutron exposure. Thus when this NP ratio is applied to the total measured photon dose from an individual film badge dosimeter, the resulting neutron dose is considered bounded. PMID:20539122

Taulbee, Timothy D; Glover, Samuel E; Macievic, Gregory V; Hunacek, Mickey; Smith, Cheryl; DeBord, Gary W; Morris, Donald; Fix, Jack

2010-07-01

56

Atom Interferometers  

E-print Network

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

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

2007-12-21

57

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

NASA Astrophysics Data System (ADS)

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.

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

2010-05-01

58

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

SciTech Connect

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.

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

59

VLA/Goldstone (California) planetary radar results  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

60

Michelson Interferometer  

NASA Technical Reports Server (NTRS)

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.

Rogers, Ryan

2007-01-01

61

Condor equatorial electrojet campaign: Radar results  

Microsoft Academic Search

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

Erhan Kudeki; Bela G. Fejer; Donald T. Farley; Christian Hanuise

1987-01-01

62

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

PubMed

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

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

63

Standard practice for measurement of the glass dissolution rate using the single-pass flow-through test method  

E-print Network

1.1 This practice describes a single-pass flow-through (SPFT) test method that can be used to measure the dissolution rate of a homogeneous silicate glass, including nuclear waste glasses, in various test solutions at temperatures less than 100°C. Tests may be conducted under conditions in which the effects from dissolved species on the dissolution rate are minimized to measure the forward dissolution rate at specific values of temperature and pH, or to measure the dependence of the dissolution rate on the concentrations of various solute species. 1.2 Tests are conducted by pumping solutions in either a continuous or pulsed flow mode through a reaction cell that contains the test specimen. Tests must be conducted at several solution flow rates to evaluate the effect of the flow rate on the glass dissolution rate. 1.3 This practice excludes static test methods in which flow is simulated by manually removing solution from the reaction cell and replacing it with fresh solution. 1.4 Tests may be conducted wit...

American Society for Testing and Materials. Philadelphia

2010-01-01

64

Permethrin absorption not detected in single-pass perfused rabbit ear, and absorption with oxidation of 3-phenoxybenzyl alcohol.  

PubMed

Isolated rabbit ears were single-pass perfused with a protein-free medium. Permethrin (0.05-23.5%, w/w) was applied in four distinct ointments. Permethrin, 3-phenoxybenzyl alcohol, 3-phenoxybenzaldehyde, and 3-phenoxybenzoic acid were analysed by HPLC. Permethrin was not detected in the effluent. The permeation coefficient, calculated from the detection limit was < 7.3 x 10(-12) (cm/sec). The appearance rate of the 3-phenoxybenzyl moieties in the effluent agreed with the absorption of the corresponding impurities in the various ointments. In supernatant of homogenised skin, the hydrolysis rate of permethrin was linear; about 4 pmol/min per cm2 at 10 microM substrate concentration. The proportion of 3-phenoxybenzoic acid, a further metabolite of 3-phenoxybenzyl alcohol increased when an oxidizing co-factor system was added. The appearance rate in the effusate of 3-phenoxybenzyl alcohol following the lipophobic ointment was five times faster than from isopropyl myristate. The formation rate of 3-phenoxybenzoic acid followed saturation kinetics. Occupational systemic poisoning by dermal absorption of permethrin seems very unlikely since humans bear more epithelial cell layers than rabbits. These experiments do not contradict, however, possible paraesthesia during systemic poisoning after inhalation or ingestion of the pyrethroid-containing aerosols used in agriculture. PMID:9049055

Bast, G E; Taeschner, D; Kampffmeyer, H G

1997-01-01

65

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

SciTech Connect

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.

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

2005-06-15

66

Green light source by single-pass second harmonic generation with laser and crystal in a tilted butt joint setup  

NASA Astrophysics Data System (ADS)

In this work a compact green laser light source is presented based on a single-pass second harmonic generation (SHG) in non-linear material. The green light source consists of a distributed feedback (DFB) laser with a monolithically integrated power amplifier (PA) and a periodically poled lithium niobate (PPLN) crystal with a ridge waveguide. To achieve the smallest size and to reduce the number of parts to be assembled, a direct coupling approach is implemented without using any lens. The waveguide of the laser is bent and the facet of the crystal is tilted and AR-coated in order to reduce undesired reflections and to increase the stability of operation. By varying the injection current of the amplifier the infrared output power of the laser changes proportionally. The wavelength remains stable during current variation and in that way the green optical output power can also be modulated. No additional external modulator is required for the generation of distinct green light levels. At a wavelength of 530 nm, a green optical output power of more than 35 mW is achieved for injection currents of 93 mA and 400 mA through the DFB section and amplifier section respectively.

Wiedmann, J.; Scholz, F.; Tekin, T.; Marx, S.; Lang, G.; Schröder, H.; Brox, O.; Erbert, G.

2009-02-01

67

Special relativity and interferometers  

NASA Technical Reports Server (NTRS)

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.

Han, D.; Kim, Y. S.

1988-01-01

68

Phase shifting interferometer  

DOEpatents

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.

Sommargren, G.E.

1999-08-03

69

Phase shifting interferometer  

DOEpatents

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.

Sommargren, Gary E. (Santa Cruz, CA)

1999-01-01

70

Radar Entomology  

NSDL National Science Digital Library

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

0000-00-00

71

Radar principles  

NASA Technical Reports Server (NTRS)

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.

Sato, Toru

1989-01-01

72

Meteor wind observations with the MU radar  

Microsoft Academic Search

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

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

1991-01-01

73

Condor equatorial electrojet campaign: Radar results  

SciTech Connect

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.

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

1987-12-01

74

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

PubMed Central

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

Alexander, John

2011-01-01

75

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

SciTech Connect

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)

Neeway, James J.; Qafoku, Nikolla P.; Williams, Benjamin D.; Valenta, Michelle M.; Cordova, Elsa A.; Strandquist, Sara C.; Dage, DeNomy C.; Brown, Christopher F. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

2012-07-01

76

N-isopropyl-(/sup 123/I)p-iodoamphetamine: single-pass brain uptake and washout; binding to brain synaptosomes; and localization in dog and monkey brain  

SciTech Connect

The kinetics of N-isopropyl-p-(/sup 123/I)iodoamphetamine in rat brains were determined by serial measurements of brain uptake index (BUI) after intracarotid injection; also studied were its effects on amine uptake and release in rat's brain cortical synaptosomes; and its in vivo distribution in the dog and monkey. No specific localization in brain nuclei of the dog was seen, but there was progressive accumulation in the eyes. Rapid initial brain uptake in the ketamine-sedated monkey was noted, and further slow brain uptake occurred during the next 20 min but without retinal localization. High levels of brain activity were maintained for several hours. The quantitative initial single-pass clearance of the agent in the brain suggests its use in evaluation of regional brain perfusion. Its interaction with brain amine-binding sites suggests its possible application in studies of cerebral amine metabolism.

Winchell, H.S. (Medi-Physics, Inc., Emeryville, CA); Horst, W.D.; Braun, L.; Oldendorf, W.H.; Hattner, R.; Parker, H.

1980-10-01

77

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

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.

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. (Washington Univ. School of Medicine, St. Louis, MO (USA))

1990-03-01

78

Fizeau plasma interferometer  

SciTech Connect

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

Frank, A.M.

1980-01-01

79

Phase shifting diffraction interferometer  

DOEpatents

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.

Sommargren, G.E.

1996-08-29

80

The Palomar Testbed Interferometer  

NASA Technical Reports Server (NTRS)

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.

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

81

Dual surface interferometer  

DOEpatents

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.

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

1980-09-12

82

Phase shifting diffraction interferometer  

DOEpatents

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.

Sommargren, Gary E. (Santa Cruz, CA)

1996-01-01

83

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

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

84

The meteor radar as a tool for upper atmosphere research  

NASA Astrophysics Data System (ADS)

Meteor radars provide measurements of the upper mesosphere-lower thermosphere neutral wind field by using the reflection of electromagnetic waves from meteor trails. These radars are relatively inexpensive and provide an excellent means of monitoring the mean winds and tides in the 80-100 km region. Recently new techniques have been developed to detect meteor echoes from other ground-based radar systems operating in the HF/VHF frequency range. The meteor echo information augments the data that is routinely collected by these radars. In this paper I will review the meteor radar technique and emphasize new methods of detection of meteor echoes on Mesosphere-Stratosphere-Troposphere (ST/MST) radars and on the Imaging Doppler Interferometer (IDI) radar.

Avery, S. K.

85

Heterodyne Interferometer Angle Metrology  

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

86

Radar astronomy  

Microsoft Academic Search

Radar Astronomy is a new and growing branch of Astronomy. Although it seems that radio echo studies must be confined to the solar system, they can play an important part in developing our understanding of the Sun and the planets. At the present time these objects are barely detectable by radar techniques and much of the work has been concerned

J. V. Evans

1960-01-01

87

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

SciTech Connect

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.

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

2013-01-01

88

Capric Acid Absorption in the Presence of Hydroxypropyl-?-Cyclodextrin in the Rat Ileum using the In Situ Single-Pass Perfusion Technique.  

PubMed

The purpose of the present study was to gain quantitative mechanistic insight into the role cyclodextrin carriers may play in the intestinal absorption of highly lipophilic molecules. The physical model approach was employed to investigate capric acid absorption in the rat ileum using the in situ single-pass method with 2-hydroxypropyl-?-cyclodextrin (HPB) present in the perfusate. Two physical models were examined: the flat surface model in which the intestinal wall was treated as a hollow, smooth, circular cylinder, and the villus model in which the intestinal surface allowed for the presence of villi. Capric acid absorption was found to be essentially 100% aqueous boundary layer controlled at low HPB concentrations and increasingly membrane controlled at the higher HPB concentrations. Theoretical calculations based on the experimental data and model parameters were found to be consistent with: at low HPB concentrations, capric acid was mainly absorbed at the villus tips and there was very little capric acid penetration into the intervillus space; in contrast, at 50 mM HPB, there was considerable capric acid penetration into the intervillus space, this corresponding to around a 4.5-fold increase in the accessible area for absorption when compared with 0 mM HPB. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci. PMID:25393711

Hymas, Richard V; Ho, Norman F H; Higuchi, William I

2014-11-12

89

The interferometer in radio astronomy  

Microsoft Academic Search

A theory is developed for the response of a two-element radio interferometer to a partially coherent field, without restriction as to bandwidth or antenna properties. It is shown that for a completely incoherent source the narrow-band interferometer output is a component of the Fourier transform of the source brightness, which can therefore be mapped by repeated interferometer observations. A partially

N. C. Mathur

1968-01-01

90

Rotatable shear plate interferometer  

DOEpatents

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.

Duffus, Richard C. (Livermore, CA)

1988-01-01

91

The Fizeau Interferometer Testbed  

Microsoft Academic Search

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

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

2002-01-01

92

Dual beam optical interferometer  

NASA Technical Reports Server (NTRS)

A dual beam interferometer device is disclosed that enables moving an optics module in a direction, which changes the path lengths of two beams of light. The two beams reflect off a surface of an object and generate different speckle patterns detected by an element, such as a camera. The camera detects a characteristic of the surface.

Gutierrez, Roman C. (Inventor)

2003-01-01

93

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

PubMed

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

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

2013-03-12

94

A systematic examination of the in vitro Ussing chamber and the in situ single-pass perfusion model systems in rat ileum permeation of model solutes.  

PubMed

In situ and in vitro intestinal absorption in the rat ileum was systematically studied and mechanistically quantified in terms of permeability coefficients (P) of a series of [(3)H]steroids as model transcellular permeants, [(3)H]taurocholate utilizing the active membrane transport systems to define the aqueous boundary layer (ABL), and [(14)C]urea and [(14)C]mannitol as pore-hindered paracellular diffusants. In situ single-pass perfusion experiments were performed in isolated ileal segments and blood samples were collected from the cannulated mesenteric vein. For the in vitro experiments, an excised, serosal and muscular layer-removed, ileal tissue was mounted in the Ussing chamber diffusion cells. In situ and in vitro P values versus logarithm of the partition coefficient in n-octanol/water (log K) of the steroids were characterized by a sigmoidal-shaped curve in which plateau values were attained for the highly lipophilic steroids with log K greater, similar 2.5. The in situ and in vitro transport barriers in series were viewed as ABL/mucosal epithelium and ABL/mucosal epithelium/submucosal tissue, respectively. Within this framework and the use of experimental strategies and theoretical reasoning, the transport barriers of the steroids were quantitatively delineated and the rate-determining barriers identified. In the plateau region, the analyses indicate that the in situ absorption of the lipophilic steroids was essentially ABL controlled, whereas the in vitro absorption was about equally controlled by diffusion across the ABL and submucosal tissue. The in situ and in vitro pore radii of the paracellular route were 7.2 and 9.2 A, respectively, and the difference was likely the result of perturbation of the tight junctions during the in vitro preparation of the ileal tissue. PMID:12532384

Tsutsumi, Keiko; Li, S Kevin; Ghanem, Abdel-Halim; Ho, Norman F H; Higuchi, William I

2003-02-01

95

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

SciTech Connect

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.

Ebert, W. L.; Chemical Engineering

2007-01-29

96

The Antarctic Planet Interferometer  

NASA Technical Reports Server (NTRS)

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.

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

97

One-element interferometer  

NASA Astrophysics Data System (ADS)

We apply the phase-switching method of Ryle to convert single dish radio telescopes to one-element interferometers and thereby accord them the benefit of correlation measurements, viz. to measure only the flux from the celestial sources avoiding contributions from the receiver and the atmosphere. This application has many uses: (a) enables single dishes to image the sky efficiently without the need to scan, measuring all sources, point, extended, spectral and continuum, with both bolometric and coherent receivers; (b) enables adding reliable short-spacing data to existing interferometers such as Atacama Large Millimetre-wave Array,, mitigating calibration issues; (c) enables ground-based NIR/MIR imaging to accurately remove atmospheric contributions; (d) can be adapted to provide an alternate surface measurement method for telescopes.

Balasubramanyam, Ramesh

2014-11-01

98

The Tidbinbilla interferometer  

NASA Technical Reports Server (NTRS)

This paper describes a technique to detect and identify weak, small-diameter radio sources with flux densities in the millijansky range. An interferometer system is proposed which will use existing 64 m and 24 m antennas of the Tidbinbilla Deep Space Network near Canberra. Design parameters of the system are described, and a schematic is presented with attention to low-noise traveling wave masers, and phase oscillation devices.

Batty, M. J.; Jauncey, D. L.; Gulkis, S.; Yerbury, M. J.

1977-01-01

99

Multipulsed dynamic moire interferometer  

DOEpatents

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.

Deason, Vance A. (Idaho Falls, ID)

1991-01-01

100

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

Microsoft Academic Search

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

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

2000-01-01

101

TIMED Doppler Interferometer  

NASA Technical Reports Server (NTRS)

The Timed Doppler Interferometer (TIDI) will accurately and precisely determine the global vector MLTI (Mesosphere and Lower Thermosphere) wind, temperature, and density profiles. It will measure characteristics of the gravity wave and planetary wave spectra. The tidal characteristics of temperature, density, and wind in the MLTI will be determined. The neutral and ion winds will be measured to characterize the electrodynamical behavior of the MLTI. Oxygen and O2 abundances and nocticulent cloud activity will be measured. This review goes into the calibration and error sources, optical design, mechanisms design, detector design, electronics design, microprocessor and flight software design, and quality assurance and parts.

Killeen, Timothy L. (Principal Investigator)

1995-01-01

102

Improved Skin Friction Interferometer  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

103

Solar Radar  

NASA Astrophysics Data System (ADS)

Radar echoes from the Sun were first detected in 1959 at 25 MHz and an extensive set of measurements was made at 38 MHz between 1960 and 1969. The results were unexpected and could not be explained at the time. Interest in the technique waned and radar astronomy evolved to the use of higher frequencies so it became impossible to repeat the measurements. The early observations can be explained in the light of our present understanding of the corona. New radar observations, with correlative optical, UV, and soft X-ray observations, would be very useful in probing the corona near the origin of the solar wind. Radar measures the range to the reflection point and the plasma velocity at the reflection point. Reflection occurs where the dielectric constant goes to zero, which is polarization dependent. Thus dual polarization observations provide estimates of the electron density, magnetic field, and velocity at the reflection point. Solar echoes can be observed at frequencies between 18 MHz and 100 MHz, corresponding to reflection heights between (roughly) 1.8 Rs and 1.15 Rs. It may be possible to operate up to 200 MHz and probe to the edge of the transition region. Here we will review the early observations; explain their basic features; outline existing and potential opportunities for new observations; and speculate on the future development of the technique.

Coles, W. A.

2002-12-01

104

JET polari-interferometer  

NASA Astrophysics Data System (ADS)

A multichannel far-infrared interferometer used on the Joint European Torus (JET) is described. The light source is a 195-?m DCN laser. The instrument is of the Mach-Zehnder type, with a heterodyne detection system. The modulation frequency (100 kHz) is produced by diffraction from a rotating grating. There are six vertical and two oblique channels. The latter rely on retroreflection from mirrors mounted on the vessel wall. Their vibration is compensated by a second wavelength interferometer at 118.8 ?m. The various subsystems are described, with emphasis on features necessitated by (a) large path lengths, (b) remote handling requirements, (c) fluctuations in atmospheric humidity, and (d) unmanned automatic operation. Typical measurements, along with real-time and off-line data analysis, are presented. The phase-shift measurement is made with an accuracy of (1)/(20) of a fringe, corresponding to a line-integrated electron density of 5×1017 m-2. Comparison with other electron density diagnostics are shown. The introduction of additional optics allows measurements of the Faraday effect and a determination of the poloidal magnetic field distribution. The signal processing and data analysis are described. Errors introduced by the calibration procedure, birefringence of the probing beams, toroidal field pickup, the flux geometry, and the density profile are considered. The Faraday angle is measured with an accuracy of 5% and a time resolution of 1-10 ms. The poloidal magnetic field is deduced with an accuracy of ±15%.

Braithwaite, G.; Gottardi, N.; Magyar, G.; O'Rourke, J.; Ryan, J.; Véron, D.

1989-09-01

105

Status of the Jicamarca radar  

NASA Astrophysics Data System (ADS)

The capabilities of the large 50-MHz radar at Jicamarca for mesosphere-stratosphere-troposphere MST observations were discussed in some detail. Hence this description will be quite brief and will concentrate on recent improvements in the facility. The radar is located about 20 km from Lima, Peru. It is well shielded by surrounding mountains, and most of the ground clutter is restricted to ranges of 15 km or less. The antenna consists of 18,432 half-wave dipoles (9216 crossed pairs) covering an area of 290 m by 290 m and divided up into 64 independent modules which can be individually phased and/or used as separate antennas in any way desired. The whole array can be steered about 3 degrees from the on-axis position (the limit is the beam width of the individual modules, which cannot be steered), and any polarization can be arranged. Even with this limited steerability it is straightforward to determine vector wind velocities by pointing segments of the antenna in different directions. The radar can also be used as in interferometer.

Farley, T.

1984-12-01

106

An improved interferometer design for use with meteor radars  

Microsoft Academic Search

The measurement of the directions of radio meteors with an inter- ferometric system is beset by two problems: (1) The ambiguity in the measured directions for antennas spaced by more than )\\/2 and (2) the effects of mutual impedance when the antennas are spaced at )\\/2 and less to avoid these ambiguities. In this paper we discuss the effects of

J. Jones; A. R. Webster; W. K. Hocking

1998-01-01

107

The Fizeau Interferometer Testbed  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

108

Heterodyne imaging speckle interferometer  

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

109

MIT's interferometer CST testbed  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

110

A Fizeau interferometer system with double-pass and stitching for characterizing the figure error of large (>1m) synchrotron optics  

NASA Astrophysics Data System (ADS)

A Fizeau interferometer based system has been developed to measure the figure error of large synchrotron optics using single-pass, double-pass, and stitching geometries. The system, which uses a ?/100 reference flat, is designed to measure optics up to 1.5m in length, and is capable of nanometer level repeatability. Fizeau measurements, in single pass geometry, are conventionally limited to the diameter of the laser beam, typically 150mm or 300mm. Stitching adjacent fields of view together or using a double-pass geometry, allows much larger optics to be characterized. Results for the single-pass, double-pass, and stitching geometries are shown to give consistent figure error values. Data is also in good agreement with an autocollimator-based slope profiler. The Fizeau method is also advantageous since data can be acquired in less than 1 minute, particularly useful for characterizing the many degrees of freedom of active or adaptive optics. To obtain results consistent with alternative techniques, the importance of an a priori knowledge of the surface topography of the reference optics is also demonstrated.

Ludbrook, G. D.; Alcock, S. G.; Sawhney, K. J. S.

2009-06-01

111

Weather Radar Fundamentals  

NSDL National Science Digital Library

This 2-hour module presents the fundamental principles of Doppler weather radar operation and how to interpret common weather phenomena using radar imagery. This is accomplished via conceptual animations and many interactive radar examples in which the user can practice interpreting both radar reflectivity and radar velocity imagery. Although intended as an accelerated introduction to understanding and using basic Doppler weather radar products, the module can also serve as an excellent refresher for more experienced users.

COMET

2012-03-21

112

Balloon Exoplanet Nulling Interferometer (BENI)  

NASA Technical Reports Server (NTRS)

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.

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

113

Compact portable diffraction moire interferometer  

DOEpatents

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.

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

1989-01-01

114

Compact portable diffraction moire interferometer  

DOEpatents

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.

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

1988-05-23

115

Interferometer with dynamic reference  

NASA Astrophysics Data System (ADS)

Interferometric testing of optical surfaces is problematic when strong asphericities are present. The spatial frequencies of the interference fringes exceed the detector resolution where the slope difference between test beam and reference beam is too large. CGHs are frequently used to avoid this effect but availability and flexibility is a problem. Alternatively we propose a new method to extend the dynamic range of interferometric measurements. For this purpose the reference beam in an interferometer is adapted. An active element containing a spatial light modulator (SLM) is used to vary the slope of the reference beam within a few degrees in both x- and y-directions. Hereby different areas of the interferogram become evaluable. Furthermore the active element can introduce phase shifts necessary for the phase shift interferometry algorithms. Several interferograms with different reference beam slopes are recorded and finally the phase functions are "stitched" together. By using an SLM for the reference beam tilt, no mechanical motion of any hardware which would limit the accuracy is necessary. A calibration of the tilts can be performed with interferometric accuracy.

Liesener, Jan; Tiziani, Hans J.

2004-02-01

116

Surface profiling interferometer  

DOEpatents

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.

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

117

Selected tendencies of modern radars and radar systems development  

Microsoft Academic Search

This paper presents modern radars and radar systems problems caused by troubles and dangers connected with actual battlefield conditions. The usefulness of the phased array radar (PAR), low probability of intercept (LPI) radar and the multi-junction radar (MFR) has been described from the point of view of the single radar using. Moreover chosen aspects of the modem radar systems development,

J. F. Pietrasinski; T. W. Brenner; C. J. Lesnik

1998-01-01

118

Netted radar sensing  

Microsoft Academic Search

Future radar applications are beginning to stretch monostatic radar systems beyond their fundamental sensitivity and information limits. Networks of smaller radar systems can offer a route to overcome these limitations; for example, networks of radar sensors can counter stealth technology whilst simultaneously providing additional information for improved target classification. More generally, multiple independent sensors can provide an energetically more efficient

C. J. Baker; A. L. Hume

2003-01-01

119

Wind shear radar simulation  

NASA Technical Reports Server (NTRS)

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.

Britt, Charles L.

1988-01-01

120

Radar Ionospheric Impact Mitigation  

Microsoft Academic Search

New ionospheric modeling technology is being developed to improve correction of ionospheric impacts on the performance of ground-based space-surveillance radars (SSRs) in near-real-time. These radars, which detect and track space objects, can experience significant target location errors due to ionospheric delay and refraction of the radar signals. Since these radars must detect and track targets essentially to the radar horizon,

G. Bishop; D. Decker; C. Baker

2006-01-01

121

Temporal analysis of a landslide by means of a ground-based SAR Interferometer  

Microsoft Academic Search

A ground-based synthetic aperture radar (GB-SAR) interferometer is used to retrieve the velocity field of a landslide. High-resolution images are obtained by means of a time domain SAR processor. An in-depth analysis of the sequence of SAR interferograms enables the recognition of a slowly deforming upper scarp in the scene, and a debris flow that feeds the accumulation zone of

Davide Leva; Giovanni Nico; Dario Tarchi; Joaquim Fortuny-Guasch; Alois J. Sieber

2003-01-01

122

Fiber-based swept-source terahertz radar.  

PubMed

We demonstrate an all-terahertz swept-source imaging radar operated at room temperature by using terahertz fibers for radiation delivery and with a terahertz-fiber directional coupler acting as a Michelson interferometer. By taking advantage of the high water reflection contrast in the low terahertz regime and by electrically sweeping at a high speed a terahertz source combined with a fast rotating mirror, we obtained the living object's distance information with a high image frame rate. Our experiment showed that this fiber-based swept-source terahertz radar could be used in real time to locate concealed moving live objects with high stability. PMID:20436563

Huang, Yu-Wei; Tseng, Tzu-Fang; Kuo, Chung-Chiu; Hwang, Yuh-Jing; Sun, Chi-Kuang

2010-05-01

123

Surface profilometry by wavelength scanning Fizeau interferometer  

Microsoft Academic Search

We have applied wavelength scanning interferometry to Fizeau interferometer for surface profilometry. This interferometer is free from ambiguity of the sign in the measurement result. It is more compact in setup than the Michelson interferometer used previously. Experimental results from a step and a dip on a mirror surface are shown. In the focal depth of imaging system, we could

Akihiro Yamamoto; Ichirou Yamaguchi

2000-01-01

124

Microwave interferometer controls cutting depth of plastics  

NASA Technical Reports Server (NTRS)

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

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

1969-01-01

125

Interferometer for the measurement of plasma density  

DOEpatents

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.

Jacobson, Abram R. (Los Alamos, NM)

1980-01-01

126

Holographic Twyman-Green interferometer  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

127

Building the Fizeau interferometer testbed  

Microsoft Academic Search

The Fizeau interferometer testbed (FIT) is a collaborative effort between NASA's Goddard Space Flight Center, the Naval Research Laboratory, Sigma Research and Engineering Corp., and the University of Maryland. The testbed is 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

Richard G. Lyon; Kenneth G. Carpenter; Hubert Huet; Paul Cottle; Peter Petrone; Peter Dogoda; Peter Liiva; Joe Marzouk; Gregory Solyar; L. Mazzuca; X. Zhang

2004-01-01

128

Radar tomography  

NASA Astrophysics Data System (ADS)

Results of experimental researches on radar sounding of non-uniform mediums and objects with use as multi frequency scanning in a UWB strip (from 0.5 up to 17 GHz), and sub nanosecond impulses are considered. It is shown, that addition of measurements by angular and spatial scanning with SAR technologies to realize 3-D tomography inhomogeneous with the spatial resolutions about 1 cm at the physical models of interaction of electromagnetic radiation with substance in which dominating mechanisms are allocated lay. It allows to simplify essentially the decision of inverse problems and to use fast algorithms of their realization. Focusing of radiation is carried out with use of mirrors, lenses, and also methods of 3-D coordinated filtrations with regularization. The examples confirming working capacity of a method for without contact tomography of structure of a forest, detection and visualization landmines hidden under a rough surface of sand are resulted. The description of the developed experimental installations is given. It is shown, that using of UWB radiation allows raising considerably accuracy of measurements at preservation of a real time scale of data processing.

Yakubov, V. P.; Telpuchovski, E. D.; Zepelev, G. M.; Klokov, A. V.; Moiseenko, N. A.; Novik, S. N.; Suhanov, D. Ya.; Yakubova, O. V.

2006-11-01

129

Remorque RADAR Description technique  

E-print Network

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

Heurteaux, Yanick

130

The MU radar  

NASA Astrophysics Data System (ADS)

The middle atmosphere (stratosphere, mesosphere, and lower thermosphere) is now being studied intensively. Mesosphere-stratosphere-troposphere (MST) radars are playing a vital role in observing middle atmospheric motions. These radars receive very weak echoes caused by scattering from atmospheric density fluctuations that are produced by clear air turbulence. These irregularities move with the local wind so that the Doppler shift of the radar echo power spectrum gives the component of the local wind along the line of sight of the radar beam.

Kato, S.

131

Temperature fluctuations near the mesopause inferred from meteor observations with the middle and upper atmosphere radar  

Microsoft Academic Search

Using meteor echo measurements with the middle and upper atmosphere (MU) radar (35 deg N, 136 deg E), operated at 46.5 MHz, we examined time-height variation of the ambipolar diffusion coefficient D, determined from the decay rate of meteor echoes. The height of a meteor trail was determined with an accuracy of about 1 km, by using an interferometer for

Masaki Tsutsumi; Toshitaka Tsuda; Takuji Nakamura; Shoichiro Fukao

1994-01-01

132

Lunar radar backscatter studies  

NASA Technical Reports Server (NTRS)

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.

Thompson, T. W.

1979-01-01

133

Synthetic aperture radar interferometry  

Microsoft Academic Search

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 characteristic of the surface. By exploiting the phase of the coherent radar signal, interferometry has transformed radar remote sensing from a largely interpretive science to a quantitative tool, with applications in cartography, geodesy, land cover

PAUL A. ROSEN; SCOTT HENSLEY; IAN R. JOUGHIN; FUK K. LI; SØREN N. MADSEN; ERNESTO RODRÍGUEZ; RICHARD M. GOLDSTEIN

2000-01-01

134

Radar hydrology: rainfall estimation  

Microsoft Academic Search

Radar observations of rainfall and their use in hydrologic research provide the focus for the paper. Radar-rainfall products are crucial for input to runoff and flood prediction models, validation of satellite remote sensing algorithms, and for statistical characterization of extreme rainfall frequency. In this context we discuss the issues of radar-rainfall product development, and the theoretical and practical requirements of

W. F. Krajewski; J. A. Smith

2002-01-01

135

Netted radar sensing  

Microsoft Academic Search

In this paper we consider a number of aspects illustrating how networks of radar sensor systems (rather than a single monostatic radar) can offer a counter to stealth technology whilst simultaneously providing more detailed information for improved target detection, classification and location. The netted radar equation is developed, coverage, detection and location performance are quantified, and the potential utility of

A. L. Hume; C. J. Baker

2001-01-01

136

Customizable Digital Receivers for Radar  

NASA Technical Reports Server (NTRS)

Compact, highly customizable digital receivers are being developed for the system described in 'Radar Interferometer for Topographic Mapping of Glaciers and Ice Sheets' (NPO-43962), NASA Tech Briefs, Vol. 31, No. 7 (August 2007), page 72. The receivers are required to operate in unison, sampling radar returns received by the antenna elements in a digital beam-forming (DBF) mode. The design of these receivers could also be adapted to commercial radar systems. At the time of reporting the information for this article, there were no commercially available digital receivers capable of satisfying all of the operational requirements and compact enough to be mounted directly on the antenna elements. A provided figure depicts the overall system of which the digital receivers are parts. Each digital receiver includes an analog-to-digital converter (ADC), a demultiplexer (DMUX), and a field-programmable gate array (FPGA). The ADC effects 10-bit band-pass sampling of input signals having frequencies up to 3.5 GHz. The input samples are demultiplexed at a user-selectable rate of 1:2 or 1:4, then buffered in part of the FPGA that functions as a first-in/first-out (FIFO) memory. Another part of the FPGA serves as a controller for the ADC, DMUX, and FIFO memory and as an interface between (1) the rest of the receiver and (2) a front-panel data port (FPDP) bus, which is an industry-standard parallel data bus that has a high data-rate capability and multichannel configuration suitable for DBF. Still other parts of the FPGA in each receiver perform signal-processing functions. The digital receivers can be configured to operate in a stand-alone mode, or in a multichannel mode as needed for DBF. The customizability of the receiver makes it applicable to a broad range of system architectures. The capability for operation of receivers in either a stand-alone or a DBF mode enables the use of the receivers in an unprecedentedly wide variety of radar systems.

Moller, Delwyn; Heavey, Brandon; Sadowy, Gregory

2008-01-01

137

Status of the LBT interferometer  

NASA Astrophysics Data System (ADS)

The Large Binocular Telescope Interferometer, a thermal infrared imager and nulling interferometer for the LBT, is currently being integrated and tested at Steward Observatory. The system consists of a general purpose or universal beamcombiner (UBC) and three camera ports, one of which is populated currently by the Nulling and Imaging Camera (NIC). Wavefront sensing is carried out using pyramid-based "W" units developed at Arcetri Observatory. The system is designed for high spatial resolution, high dynamic range imaging in the thermal infrared. A key project for the program is to survey nearby stars for debris disks down to levels which may obscure detection of Earth-like planets. During 2007-2008 the UBC portion of the LBTI was assembled and tested at Steward Observatory. Initial integration of the system with the LBT is currently in progress as the W units and NIC are being completed in parallel.

Hinz, Philip M.; Bippert-Plymate, Teresa; Breuninger, Andy; Connors, Tom; Duffy, Brian; Esposito, Simone; Hoffmann, William; Kim, Jihun; Kraus, Joe; McMahon, Thomas; Montoya, Manny; Nash, Richard; Durney, Olivier; Solheid, Elliott; Tozzi, Andrea; Vaitheeswaran, Vidhya

2008-07-01

138

Radar Meteorology Tutorial  

NSDL National Science Digital Library

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

McNoldy, Brian

139

Fiber Sagnac interferometer temperature sensor  

Microsoft Academic Search

A modified Sagnac interferometer-based fiber temperature sensor is proposed. Polarization independent operation and high temperature sensitivity of this class of sensors make them cost effective instruments for temperature measurements. A comparison of the proposed sensor with Bragg grating and long-period grating fiber sensors is derived. A temperature-induced spectral displacement of 0.99 nm\\/K is demonstrated for an internal stress birefringent fiber-based

A. N. Starodumov; L. A. Zenteno; D. Monzon; E. De La Rosa

1997-01-01

140

Polarized-interferometer feasibility study  

NASA Technical Reports Server (NTRS)

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.

Raab, F. H.

1983-01-01

141

Single Pass Electron Cooling Simulations for MEIC  

SciTech Connect

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.

Bell, G. I. [Tech-X Corp.; Pogorelov, I. V. [Tech-X Corp.; Schwartz, B. T. [Tech-X Corp.; Zhang, Yuhong [JLAB; Zhang, He [JLAB

2013-12-01

142

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

143

Nonlocal polarization interferometer for entanglement detection  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

144

A nonlocal polarization interferometer for entanglement detection  

E-print Network

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 anti-diagonal 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 non-local interference, while single photon interference is suppressed. This interferometer also allows for a unique version of the CHSH-Bell test where the local reality is the photon polarization. We present the relevant theory and experimental results.

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

2014-10-22

145

Radar Imaging Systems Joseph Charpentier  

E-print Network

Radar Imaging Systems Joseph Charpentier Department of Computing Sciences Villanova University types of radar imaging systems; synthetic aperture radar (SAR), through-the-wall radar, and digital holographic near field radar. Each system surveyed experiments that improved the quality of the resulting

146

LPI radar: fact or fiction  

Microsoft Academic Search

LPI radar is a system that consists of a radar and ES system. Its performance depends on both components. An LPI performance factor is derived and applied to several examples. Operational LPI radars are described. A digital LPI radar detector is described and test results presented. A recent book on LPI radar received a number of somewhat critical reviews that

D. C. Schleher

2006-01-01

147

Alignment of a two-beam interferometer  

NASA Technical Reports Server (NTRS)

Two beam interferometers have been proposed for space applications such as sensing the shape of a large antenna. Since alignment and adjustment of interferometers have long been considered difficult laboratory tasks, the question of making their operation sufficiently automatic for space applications is a serious one. As a first step in addressing this question certain manual procedures, which may not be well known, have been collected from widely scattered sources. These techniques are illustrated by two examples: (1) the alignment of a Mach-Zehnder interferometer and the adjustment of fringe location. (2) The adjustment of a Michelson interferometer for zero path difference (white light fringes).

Tubbs, E. F.

1980-01-01

148

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

149

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

150

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

SciTech Connect

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.

Golovashkin, A. I.; Zherikhina, L. N., E-mail: zherikh@sci.lebedev.ru; Tskhovrebov, A. M. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Izmailov, G. N.; Ozolin, V. V. [Moscow Aviation Institute (State Technical University) (Russian Federation)

2010-08-15

151

Planetary radar studies  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

152

Laser radar in robotics  

SciTech Connect

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.

Carmer, D.C.; Peterson, L.M. [Environmental Research Inst. of Michigan, Ann Arbor, MI (United States)

1996-02-01

153

Radar in transition  

NASA Astrophysics Data System (ADS)

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

Barton, D. K.

1984-12-01

154

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

E-print Network

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

Vaidyanathan, P. P.

155

1999 IEEE radar conference  

SciTech Connect

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.

NONE

1999-07-01

156

Caribbean Radar Cases  

NSDL National Science Digital Library

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

COMET

2013-12-31

157

Silence tracking radar  

Microsoft Academic Search

A high performance linear FMCW radar sensor and its implementation as tracking radar are presented. The radar has been built with an all-solid state transmitter with 200 mw output power and two channel receivers with 9 dB noise figure. Tracking range of more than 10 km, angle error of better than 0.5 mrad and range error of better than 5

Zhang Guanjie; Guo Min; Bao Yongjie

2001-01-01

158

Aircraft radar echoes characterization  

NASA Astrophysics Data System (ADS)

Electromagnetic wave diffraction and reflection theories enable prediction of most of the effects generated by radar echoes on aircraft. However, it is difficult to modelize some complex effects originating in canopies, radomes and cavities. In order to supplement the present theoretical knowledge by experimental results obtained on actual targets, ONERA has developed a novel analysis method allowing the generation of radar images. This method provides an efficient working tool to assist in defining radar wise discrete aerial targets.

Pouit, C.

1980-04-01

159

The Invisible Radar Triangle  

NSDL National Science Digital Library

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

RET-ENET Program, Electrical Engineering Department,

160

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

161

Generalized radar/radiometry imaging problems  

E-print Network

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

Genève, Université de

162

The DELTA Synchrotron Light Interferometer  

SciTech Connect

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

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

2004-05-12

163

Dual-prism interferometer for collimation testing  

SciTech Connect

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.

Hii, King Ung; Kwek, Kuan Hiang

2009-01-10

164

Fizeau interferometer for global astrometry in space  

Microsoft Academic Search

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

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

2004-01-01

165

AN ATOM INTERFEROMETER GYROSCOPE JAMES GREENBERG  

E-print Network

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

Cronin, Alex D.

166

A chevron beam-splitter interferometer  

NASA Technical Reports Server (NTRS)

Fully tilt compensated double-pass chevron beam splitter, that removes channelling effects and permits optical phase tuning, is wavelength independent and allows small errors in alignment that are not tolerated in Michelson, Machzender, or Sagnac interferometers. Device is very useful in experiments where background vibration affects conventional interferometers.

Breckinridge, J. B.

1979-01-01

167

102?k large area atom interferometers.  

PubMed

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

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

2011-09-23

168

Orientational atom interferometers sensitive to gravitational waves  

SciTech Connect

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.

Lorek, Dennis; Laemmerzahl, Claus; Wicht, Andreas [Center of Applied Space Technology and Microgravity, University of Bremen, Am Fallturm, D-28359 Bremen (Germany); Ferdinand-Braun-Institut fuer Hoechstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, D-12489 Berlin (Germany); Humboldt-Universitaet zu Berlin, Institut fuer Physik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)

2010-02-15

169

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

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.

Ebert, W. L.; Chemical Engineering

2006-02-28

170

GeoSAR: A Radar Terrain Mapping System for the New Millennium  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

171

Decoders for MST radars  

NASA Technical Reports Server (NTRS)

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

Woodman, R. F.

1983-01-01

172

The Cloud Radar System  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

173

Radars for the eighties  

Microsoft Academic Search

The Modular Survivable Radar (MSR), proposed by the General Electric Company as the solution to the USAF's airborne attack radar requirements, is a flexible system with ECCM and low probability of intercept (LPI) protection capabilities. The system is built with standard modular line replaceable units (LRU) and is adaptable to a wide range of performance requirements. The structure of the

M. Shohat

1979-01-01

174

Netted radar sensing  

Microsoft Academic Search

We consider how networks of radar sensors can offer a counter to stealth technology whilst simultaneously providing more detailed information for improved target classification. Specifically, it is shown how multiple independent sensors can provide an energetically more efficient collector of radar scatter. Further, the relative merits of non-coherent and coherent dependent networks are discussed particularly emphasising the balance between increased

A. L. Hume; C. J. Baker

2001-01-01

175

Aircraft radar antennas  

Microsoft Academic Search

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

Helmut E. Schrank

1987-01-01

176

Java Radar Analysis Tool  

NASA Technical Reports Server (NTRS)

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.

Zaczek, Mariusz P.

2005-01-01

177

Radar illusion via metamaterials  

NASA Astrophysics Data System (ADS)

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.

Jiang, Wei Xiang; Cui, Tie Jun

2011-02-01

178

Looking at Radar Images  

NSDL National Science Digital Library

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

179

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

180

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

181

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

E-print Network

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

Préaux, Jean-Philippe

182

Beam shuttering interferometer and method  

DOEpatents

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.

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

1993-07-27

183

Beam shuttering interferometer and method  

DOEpatents

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.

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

1993-01-01

184

X-ray shearing interferometer  

DOEpatents

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.

Koch, Jeffrey A. (Livermore, CA)

2003-07-08

185

Angle interferometer cross axis errors  

SciTech Connect

Angle interferometers are commonly used to measure surface plate flatness. An error can exist when the centerline of the double comer cube mirror assembly is not square to the surface plate and the guide bar for the mirror sled is curved. Typical errors can be one to two microns per meter. A similar error can exist in the calibration of rotary tables when the centerline of the double comer cube mirror assembly is not square to the axes of rotation of the angle calibrator and the calibrator axis is not parallel to the rotary table axis. Commercial double comer cube assemblies typically have non-parallelism errors of ten milli-radians between their centerlines and their sides and similar values for non-squareness between their centerlines and end surfaces. The authors have developed a simple method for measuring these errors and correcting them by remachining the reference surfaces.

Bryan, J.B.; Carter, D.L.; Thompson, S.L.

1994-01-01

186

Multiple spacecraft Michelson stellar interferometer  

NASA Technical Reports Server (NTRS)

Results of an orbital analysis and performance assessment of SAMSI (Spacecraft Array for Michelson Spatial Interferometry) are presented. The device considered includes two one-meter telescopes in orbits which are identical except for slightly different inclinations; the telescopes achieve separations as large as 10 km and relay starlight to a central station which has a one-meter optical delay line in one interferometer arm. It is shown that a 1000-km altitude, zero mean inclination orbit affords natural scanning of the 10-km baseline with departures from optical pathlength equality which are well within the corrective capacity of the optical delay line. Electric propulsion is completely adequate to provide the required spacecraft motions, principally those needed for repointing. Resolution of 0.00001 arcsec and magnitude limits of 15 to 20 are achievable.

Stachnik, R. V.; Arnold, D.; Melroy, P.; Mccormack, E. F.; Gezari, D. Y.

1984-01-01

187

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

188

Use and Interpretation of Radar  

NSDL National Science Digital Library

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

John Nielsen-Gammon

1996-01-01

189

Low probability of intercept radar  

Microsoft Academic Search

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

D. C. Schleher

1985-01-01

190

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 ...

191

Radar sensing of the ocean  

Microsoft Academic Search

Radar remote sensing of the ocean has been the subject of research for about 20 years. Spaceborne radar altimetry and scatterometry are approaching maturity, and synthetic-aperture radars (SAR) show great promise. The principles of radar scattering from the sea are outlined here, along with some recently discovered questions. For wind-vector scatterometry, the principle is presented, and remaining uncertainties are outlined.

RICHARD K. MOORE

1985-01-01

192

The Millimeter-Wave Bolometric Interferometer  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

193

Goldstone solar system radar  

NASA Technical Reports Server (NTRS)

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.

Jurgens, Raymond F.

1988-01-01

194

Radar Remote Sensing  

NASA Technical Reports Server (NTRS)

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.

Rosen, Paul A.

2012-01-01

195

Radar investigation of asteroids  

NASA Technical Reports Server (NTRS)

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.

Ostro, S. J.

1984-01-01

196

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

NASA Technical Reports Server (NTRS)

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.

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

1978-01-01

197

The effect of rotations on Michelson interferometers  

NASA Astrophysics Data System (ADS)

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.

Maraner, Paolo

2014-11-01

198

Active noise cancellation in a suspended interferometer  

E-print Network

We demonstrate feed-forward vibration isolation on a suspended Fabry-Perot interferometer using Wiener filtering and a variant of the common least mean square adaptive filter algorithm. We compare the experimental results ...

Driggers, Jennifer C.

199

Atom Interferometers with Scalable Enclosed Area  

NASA Astrophysics Data System (ADS)

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

Müller, Holger; Chiow, Sheng-Wey; Herrmann, Sven; Chu, Steven

2009-06-01

200

Atom interferometers with scalable enclosed area.  

PubMed

Bloch oscillations (i.e., coherent acceleration of matter waves by an optical lattice) and Bragg diffraction are integrated into light-pulse atom interferometers with large momentum splitting between the interferometer arms, and hence enhanced sensitivity. Simultaneous acceleration of both arms in the same internal states suppresses systematic effects, and simultaneously running a pair of interferometers suppresses the effect of vibrations. Ramsey-Bordé interferometers using four such Bloch-Bragg-Bloch beam splitters exhibit 15% contrast at 24variant Planck's over 2pik splitting, the largest so far (variant Planck's over 2pik is the photon momentum); single beam splitters achieve 88variant Planck's over 2pik. The prospects for reaching 100 s of variant Planck's over 2pik and applications such as gravitational wave sensors are discussed. PMID:19658985

Müller, Holger; Chiow, Sheng-wey; Herrmann, Sven; Chu, Steven

2009-06-19

201

The VLA Atmospheric Phase Interferometer  

NASA Astrophysics Data System (ADS)

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

Morris, Keith

2014-05-01

202

Stroboscopic interferometer system for dynamic MEMS characterization  

Microsoft Academic Search

We describe a computer-controlled stroboscopic phase-shifting interferometer system for measuring out-of-plane motions and deformations of MEMS structures with nanometer accuracy. To aid rapid device characterization, our system incorporates (1) an imaging interferometer that records motion at many points simultaneously without point-by-point scanning, (2) an integrated computer-control and data-acquisition unit to automate measurement, and (3) an analysis package that generates sequences

Matthew R. Hart; Robert A. Conant; Kam Y. Lau; Richard S. Muller

2000-01-01

203

Dual-beam skin friction interferometer  

NASA Technical Reports Server (NTRS)

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.

Monson, D. J. (inventor)

1981-01-01

204

Interferometer Designs for the Terrestrial Planet Finder  

NASA Technical Reports Server (NTRS)

The Terrestrial Planet Finder (TPF) is a space-based infrared interferometer that will combine high sensitivity and spatial resolution to detect and characterize planetary systems within 15 pc of our sun. TPF is a key element in NASA's Origins Program and is currently under study in its Pre-Project Phase. We review some of the interferometer designs that have been considered for starlight nulling, with particular attention to the architecture and subsystems of the central beam-combiner.

Lawson, P. R.; Dumont, P. J.; Colavita, M. M.

1999-01-01

205

Thermal Dephasing in the Laughlin Quasiparticle Interferometer  

Microsoft Academic Search

We report experiments on thermal dephasing of the Aharonov-Bohm oscillations in the novel Laughlin quasiparticle (LQP) interferometer, [1] where quasiparticles of the 1\\/3 FQH fluid execute a closed path around an island of the 2\\/5 fluid. In the 10.2 <=T <=141 mK temperature range, qualitatively, the experimental results follow a thermal dephasing dependence expected for an electron interferometer, and show

F. E. Camino; Wei Zhou; V. J. Goldman

2006-01-01

206

Portable radar simulator  

NASA Astrophysics Data System (ADS)

A portable radar simulator, when connected to a transmitting means such as a waveguide horn antenna, provides a radar signal to test a radar receiver. The portable radar simulator comprises a tunable oscillator which generates a continuous wave signal in the microwave frequency range with the desired frequency of the signal being selected by an operator. The signal generated by the tunable oscillator is supplied to a microwave switch. The microwave switch receives a control signal provided by a pulse repetition frequency generating circuit and in response to the control signal turns the switch on or off controlling the transmission of the oscillator generated signal to the wave guide horn antenna. The pulse repetition frequency generating circuit which comprises an integrated circuit timer and a monostable multivibrator provides a variable frequency and variable pulse width control signal. The frequency and pulse width of the control signal are, in turn, set by the operator.

Aw, Kenneth

1992-09-01

207

Caribbean Radar Products  

NSDL National Science Digital Library

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

2014-09-14

208

GMTI MIMO radar  

E-print Network

Multiple-input multiple-output (MIMO) extensions to radar systems enable a number of advantages compared to traditional approaches. These advantages include improved angle estimation and target detection. In this paper, ...

Bliss, Daniel W., Jr.

209

Imaging with Radar  

NSDL National Science Digital Library

This interactive activity from NOVA features synthetic aperture radar (SAR), which uses radio waves to create high-quality images. Examine SAR images of Washington, D.C., and learn about this technology's unique advantages.

2004-01-29

210

Aircraft radar antennas  

NASA Astrophysics Data System (ADS)

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.

Schrank, Helmut E.

1987-04-01

211

Downhole pulse radar  

DOEpatents

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.

Chang, Hsi-Tien

1987-09-28

212

Doppler Radar Technology  

NSDL National Science Digital Library

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

213

Downhole pulse radar  

DOEpatents

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.

Chang, Hsi-Tien (Albuquerque, NM)

1989-01-01

214

Adaptive MIMO radar waveforms  

Microsoft Academic Search

Multiple-Input, Multiple-Output (MIMO) radars enhance performance by transmitting and receiving coded waveforms from multiple locations. To date, the theoretical literature on MIMO radar has focused largely on the use of ldquoorthogonal waveforms.rdquo Practical approaches to approximate orthogonality (e.g., via waveforms characterized by low cross-correlation and low autocorrelation sidelobe levels) have also started to emerge. We show, however, that such waveforms

Daniel J. Rabideau; Lexington MA

2008-01-01

215

Achromatic self-referencing interferometer  

DOEpatents

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.

Feldman, M.

1994-04-19

216

Achromatic self-referencing interferometer  

DOEpatents

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.

Feldman, Mark (Pleasanton, CA)

1994-01-01

217

Radar Ionospheric Impact Mitigation  

NASA Astrophysics Data System (ADS)

New ionospheric modeling technology is being developed to improve correction of ionospheric impacts on the performance of ground-based space-surveillance radars (SSRs) in near-real-time. These radars, which detect and track space objects, can experience significant target location errors due to ionospheric delay and refraction of the radar signals. Since these radars must detect and track targets essentially to the radar horizon, it is necessary to accurately model the ionosphere as the radar would observe it, down to the local horizon. To correct for spatial and temporal changes in the ionosphere the model must be able to update in near-real-time using ionospheric sensor data. Since many radars are in isolated locations, or may have requirements to operate autonomously, an additional required capability is to provide accurate ionospheric mitigation by exploiting only sensor data from the radar site. However, the model must also be able to update using additional data from other types of sensors that may be available. The original radar ionospheric mitigation approach employed the Bent climatological model. This 35-year-old technology is still the means employed in the many DoD SSRs today. One more recent approach used capabilities from the PRISM model. PRISM technology has today been surpassed by `assimilative models' which employ better physics and Kalman filtering techniques. These models are not necessarily tailored for SSR application which needs to optimize modeling of very small regions using only data from a single sensor, or very few. The goal is to develop and validate the performance of innovative and efficient ionospheric modeling approaches that are optimized for the small regions applicable to ground-based radar coverage (radius of ~2000 km at ionospheric altitudes) and somewhat beyond. These approaches must adapt a continuous modeling scheme in near-real-time to be consistent with all observational data that may become available, and degrade gracefully toward a climatological representation in the absence of data. In this presentation we will discuss the issues for improving correction of ionospheric impacts on SSRs, some of the capabilities and limitations of current models, and the requirements and goals for new modeling technologies.

Bishop, G.; Decker, D.; Baker, C.

2006-12-01

218

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

E-print Network

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

Rutledge, Steven

219

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

220

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

E-print Network

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.

John G. Baker; James Ira Thorpe

2012-01-26

221

Weather Radar and Instrumentation: Laboratory Modules  

NSDL National Science Digital Library

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

222

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

223

The Ponape ST radar  

NASA Astrophysics Data System (ADS)

In May, 1984, a 50-MHz ST radar was installed on the island of Ponape in the western equatorial Pacific (7 deg N, 158 deg E) by the Aeronomy Laboratory of NOAA. The radar consists of a 100 m x 100 m array with a single, vertically directed, beam and is initially transmitting micro sec. (2.25 km) pulses. The radar is operating continuously, with Doppler spectra being recorded at approximately 1 1/2 minute intervals and sent to Boulder for later analysis. One of the principal goals of the radar is to measure vertical motions in the troposphere and lower stratosphere at a location which is within the intertropical convergence zone during part of the year. First results, during generally fair weather conditions, show detectable echoes up to about 21 km with the tropopause at 17-18 km. Once daily balloon soundings are available locally from a NOAA Weather Service Office on the island, it is planned that this radar will be joined in the coming year by two others with oblique as well as vertical beams on two yet-to-be-selected equatorial islands as part of the TOGA (Tropical Oceans Global Atmosphere) program.

Carter, D. A.; Ecklund, W. L.; Balsley, B. B.

1984-12-01

224

Process control system using polarizing interferometer  

DOEpatents

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.

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

1994-02-15

225

Furnace control apparatus using polarizing interferometer  

DOEpatents

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.

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

1995-03-28

226

Quantum correlations in a noisy neutron interferometer  

NASA Astrophysics Data System (ADS)

We investigate quantum coherences in the presence of noise by entangling the spin and path degrees of freedom of the output neutron beam from a noisy three-blade perfect crystal neutron interferometer. We find that in the presence of dephasing noise on the path degree of freedom the entanglement of the output state reduces to 0, however the quantum discord remains nonzero for all noise values. Hence even in the presence of strong phase noise nonclassical correlations persist between the spin and the path of the neutron beam. This indicates that measurements performed on the spin of the neutron beam will induce a disturbance on the path state. We calculate the effect of the spin measurement by observing the changes in the observed contrast of the interferometer for an output beam postselected on a given spin state. In doing so we demonstrate that these measurements allow us to implement a quantum eraser and a which-way measurement of the path taken by the neutron through the interferometer. While strong phase noise removes the quantum eraser, the spin-filtered which-way measurement is robust to phase noise. We experimentally demonstrate this disturbance by comparing the contrasts of the output beam with and without spin measurements of three neutron interferometers with varying noise strengths. This demonstrates that even in the presence of noise that suppresses path coherence and spin-path entanglement, a neutron interferometer still exhibits uniquely quantum behavior.

Wood, Christopher J.; Abutaleb, Mohamed O.; Huber, Michael G.; Arif, Muhammad; Cory, David G.; Pushin, Dmitry A.

2014-09-01

227

The AEI 10 m prototype interferometer  

NASA Astrophysics Data System (ADS)

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.

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

228

Mars 96 subsurface radar  

NASA Astrophysics Data System (ADS)

The Mars 96 International Scientific Mission to launch an aerostat that will drift in the Martian atmosphere for ten days is described. The stabilizing element of the aerostat (guiderope) will be dragged on the Martian surface every night. A ground penetrating radar will be installed within the guiderope. Its external surface will act as a transmit and receive antenna. A full scale model was built and tested on different soils and glaciers. Further experiments will be performed to test the full specifications. Radar potential and data processing could yield a penetrating depth down to 2.5 km with 30 m resolution on Mars. The main technical features of the radar are described. Its implementation into the guiderope is discussed. Some experimental results are presented.

Barbin, Y.; Kofman, W.; Elkine, M.; Finkelstein, M.; Glotov, V.; Zolotarev, V.

1991-12-01

229

Radar sector blanker  

NASA Astrophysics Data System (ADS)

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

Hall, Roger B.

1994-03-01

230

The MST Radar Technique  

NASA Technical Reports Server (NTRS)

The past ten year have witnessed the development of a new radar technique to examine the structure and dynamics of the atmosphere between roughly 1 to 100 km on a continuous basis. The technique is known as the MST (for Mesosphere-Stratosphere-Troposphere) technique and is usable in all weather conditions, being unaffected by precipitation or cloud cover. MST radars make use of scattering from small scale structure in the atmospheric refractive index, with scales of the order of one-half the radar wavelength. Pertinent scale sizes for middle atmospheric studies typically range between a fraction of a meter and a few meters. The structure itself arises primarily from atmospheric turbulence. The technique is briefly described along with the meteorological parameters it measures.

Balsley, B. B.

1985-01-01

231

The MST radar technique  

NASA Astrophysics Data System (ADS)

The past ten year have witnessed the development of a new radar technique to examine the structure and dynamics of the atmosphere between roughly 1 to 100 km on a continuous basis. The technique is known as the MST (for Mesosphere-Stratosphere-Troposphere) technique and is usable in all weather conditions, being unaffected by precipitation or cloud cover. MST radars make use of scattering from small scale structure in the atmospheric refractive index, with scales of the order of one-half the radar wavelength. Pertinent scale sizes for middle atmospheric studies typically range between a fraction of a meter and a few meters. The structure itself arises primarily from atmospheric turbulence. The technique is briefly described along with the meteorological parameters it measures.

Balsley, B. B.

1985-07-01

232

Side looking radar calibration study  

NASA Technical Reports Server (NTRS)

Calibration of an airborne sidelooking radar is accomplished by the use of a model that relates the radar parameters to the physical mapping situation. Topics discussed include: characteristics of the transmitters; the antennas; target absorption and reradiation; the receiver and map making or radar data processing; and the calibration process.

Edwards, W. D.

1975-01-01

233

The Shuttle Radar Topography Mission  

Microsoft Academic Search

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.

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

2007-01-01

234

Development of random signal radars  

Microsoft Academic Search

Development of random signal radar (RSR) over the past 30 years is described. Conventional methods of implementing RSR are summarized such as correlation, spectrum analysis, and anticorrelation. Some typical RSR systems are introduced, for example, noise frequency modulation CW radar, random binary phase-coded CW radar, etc., and their merits and demerits are also pointed out. Finally, RSR development trends are

Guosui Liu; Hong Gu; Weimin Su

1999-01-01

235

Interception of LPI radar signals  

Microsoft Academic Search

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

Jim P. Lee

1991-01-01

236

Comet Radar Explorer  

NASA Astrophysics Data System (ADS)

Comet Radar Explorer (CORE) is a low cost mission that uses sounding radar to image the 3D internal structure of the nucleus of Jupiter-family comet (JFC) Tempel 2. Believed to originate in the Kuiper Belt, JFCs are among the most primitive bodies in the inner solar system. CORE operates a 5 and 15 MHz Radar Reflection Imager from close orbit about the nucleus of Tempel 2, obtaining a dense network of echoes that are used to map its interior dielectric contrasts to high resolution (? m) and resolve the dielectric constants to ? m throughout the 16x8x9 km nucleus. The resulting clear images of internal structure and composition reveal how the nucleus was formed and how it has evolved. Radiometric tracking of the spacecraft orbit results in an interior mass distribution that constrains the radar-based models of interior composition. High-resolution visible and infrared color images provide the surface and exterior boundary conditions for interior models and hypotheses. They present the geology and morphology of the nucleus surface at meter-scales, and also the time-evolving activity, structure and composition of the inner coma. By making deep connections from interior to exterior, the data CORE provides will answer fundamental questions about the earliest stages of planetesimal evolution and planet formation, and lay the foundation for a comet nucleus sample return mission. CORE is led by Prof. Erik Asphaug of the University of California, Santa Cruz and is managed by JPL. It benefits from key scientific and payload contributions by ASI and CNES. The international science team has been assembled on the basis of their key involvement in past and ongoing missions to comets, and in Mars radar missions, and for their expertise in radar data analysis.

Asphaug, Erik; CORE Science Team

2010-10-01

237

Radar Investigations of Asteroids  

NASA Technical Reports Server (NTRS)

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.

Ostro, S. J.

1984-01-01

238

Spaceborne Imaging Radar Symposium  

NASA Technical Reports Server (NTRS)

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.

Elachi, C.

1983-01-01

239

Venus Radar Mapper (VRM): Multimode radar system design  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

240

Matter-wave interferometer for large molecules.  

PubMed

We demonstrate a near-field Talbot-Lau interferometer for C70 fullerene molecules. Such interferometers are particularly suitable for larger masses. Using three free-standing gold gratings of 1 microm period and a transversally incoherent but velocity-selected molecular beam, we achieve an interference fringe visibility of 40% with high count rate. Both the high visibility and its velocity dependence are in good agreement with a quantum simulation that takes into account the van der Waals interaction of the molecules with the gratings and are in striking contrast to a classical moiré model. PMID:11909334

Brezger, Björn; Hackermüller, Lucia; Uttenthaler, Stefan; Petschinka, Julia; Arndt, Markus; Zeilinger, Anton

2002-03-11

241

Continuous phase amplification with a Sagnac interferometer  

E-print Network

We describe a weak value inspired phase amplification technique in a Sagnac interferometer. We monitor the relative phase between two paths of a slightly misaligned interferometer by measuring the average position of a split-Gaussian mode in the dark port. Although we monitor only the dark port, we show that the signal varies linearly with phase and that we can obtain similar sensitivity to balanced homodyne detection. We derive the source of the amplification both with classical wave optics and as an inverse weak value.

David J. Starling; P. Ben Dixon; Nathan S. Williams; Andrew N. Jordan; John C. Howell

2009-12-16

242

(presentation) Precision Mechanisms for Space Interferometers: A Tutorial  

NASA Technical Reports Server (NTRS)

To maximize salability, spaceborne interferometer designs must minimize actuator cost while maximizing science quality and quantity. Interferometer designers must have the knowledge to design a system with the simplist, most reliable, and least expensive actuators possible.

Agronin, Michael L.

1993-01-01

243

Jamin interferometer for precise measurement of refractive index of gases  

NASA Astrophysics Data System (ADS)

Modified folded Jamin interferometer for on-line measurement of refractive index of gases was designed, constructed and tested. The accuracy of this interferometer is better than 10-6 and can be still approved about two orders by appropriate mathematical method. Interferometer is almost vibration insensitive with vibration noise equivalent to refractive index variation 2•10-9. The interferometer qualities were tested by air refractive index monitoring.

Sulc, Miroslav

2015-01-01

244

Cold atom interferometers and their applications in precision measurements  

NASA Astrophysics Data System (ADS)

Experimental realization of cold 85Rb atom interferometers and their applications in precision measurements are reported in this paper. Mach-Zehnder and Ramsey-Bordè type interferometers were demonstrated. Detailed descriptions of the interferometers are given including manipulation of cold atoms, Rabi oscillation, stimulated Raman transitions, and optical pumping. As an example of using atom interferometers in precision measurements, the quadratic Zeeman shift of hyperfine sublevels of 85Rb was determined.

Wang, Jin; Zhou, Lin; Li, Run-Bing; Liu, Min; Zhan, Ming-Sheng

2009-06-01

245

Miniaturized Ka-Band Dual-Channel Radar  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

246

Radar detection in clutter  

Microsoft Academic Search

Clutter is defined as any unwanted radar return. The presence of clutter in a range\\/Doppler cell complicates the detection of a target return signal in that cell. In order to quantify the effect of clutter on the probability of detection, we must first specify sets of models suitable for representing the clutter and target. The simplest and most common model

D. A. Shnidman

2005-01-01

247

Radar reflectivity in snowfall  

Microsoft Academic Search

Backscattering properties of dry snowflakes at different microwave frequencies are examined. It is shown that the Rayleigh approximation does not often provide the necessary accuracy for snowflake reflectivity calculations for radar wavelengths used in meteorology; however, another simple approximation, the Rayleigh-Gans approximation, can be safely used for such calculations. Reflectivity-snowfall rate relationships are derived for different snow densities and different

S. Y. Matrosov

1992-01-01

248

Impulse radar studfinder  

DOEpatents

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.

McEwan, T.E.

1995-10-10

249

Impulse radar studfinder  

DOEpatents

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.

McEwan, Thomas E. (Livermore, CA)

1995-01-01

250

Rain radar instrument definition  

NASA Astrophysics Data System (ADS)

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

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

1996-12-01

251

Rain radar instrument definition  

Microsoft Academic Search

As a result of a pre-phase a study, founded by ESA, this paper presents the definition of a spaceborne Rain Radar, candidate instrument for earth explorer precipitation mission. Based upon the description of user requirements for such a dedicated mission, a mission analysis defines the most suitable space segment. At system level, a parametric analysis compares pros and cons of

N. Vincent; J. Chenebault; Noel Suinot; P. L. Mancini

1996-01-01

252

Frequency diverse array radars  

Microsoft Academic Search

This paper presents a generalized structure for a frequency diverse array radar. In its simplest form, the frequency diverse array applies a linear phase progression across the aperture. This linear phase progression induces an electronic beam scan, as in a conventional phased array. When an additional linear frequency shift is applied across the elements, a new term is generated which

Paul Antonik; Michael C. Wicks; Hugh D. Griffiths; Christopher J. Baker

2006-01-01

253

Aircraft radar echoes characterization  

Microsoft Academic Search

Electromagnetic wave diffraction and reflection theories enable prediction of most of the effects generated by radar echoes on aircraft. However, it is difficult to modelize some complex effects originating in canopies, radomes and cavities. In order to supplement the present theoretical knowledge by experimental results obtained on actual targets, ONERA has developed a novel analysis method allowing the generation of

C. Pouit

1980-01-01

254

Radar investigation of asteroids  

NASA Technical Reports Server (NTRS)

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.

Ostro, S. J.

1986-01-01

255

Coherent and incoherent scatter radar observations during intense mid-latitude spread F  

NASA Astrophysics Data System (ADS)

An intense mid-latitude spread-F event occurred over Puerto Rico during the night of February 17, 1998. Simultaneous observations were made with the Cornell University Portable Radar Interferometer (CUPRI) located near Isabela, PR, the University of Illinois VHF radar located at Salinas, PR, GPS receivers at Isabela and St. Croix, measuring total electron content, the Arecibo incoherent scatter radar, and the Cornell All-Sky imager located at the Arecibo Observatory. This was the first time that such a broad range of complementary instrumentation captured a mid-latitude spread-F space weather event. It was the first (and still only) time that a spread-F event over the Caribbean exhibited large Doppler shifts in the VHF spectra. This event was characterized with multiple filaments that initially produced receding Doppler velocities exceeding 300 m/s as seen by CUPRI and the Illinois radar. The Arecibo incoherent scatter radar recorded line-of-sight velocities exceeding 100 m/s that moved the F-layer peak to over 400-km altitude. Airglow images of 630.0 nm emissions from F-region heights showed depleted structures oriented southeast to northwest. The large velocities observed with the radars suggest that we caught this event in a stage of explosive development. It is interesting that the first fully documented Caribbean event occurred during a magnetically active period.

Swartz, Wesley E.; Kelley, Michael C.; Makela, Jonathan J.; Collins, Stephen C.; Kudeki, Erhan; Franke, Steve; Urbina, Julio; Aponte, Nestor; Sulzer, Michael P.; González, Sixto A.

2000-09-01

256

An electron Talbot-Lau interferometer and magnetic field sensing  

NASA Astrophysics Data System (ADS)

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.

Bach, Roger; Gronniger, Glen; Batelaan, Herman

2013-12-01

257

Imaging through turbulence with a quadrature-phase optical interferometer  

Microsoft Academic Search

We present an improved technique for imaging through turbulence at visible wavelengths using a rotation shearing pupil-plane interferometer, intended for astronomical and terrestrial imaging applications. While previous astronomical rotation shearing interferometers have made only visibility modulus measurements, this interferometer makes four simultaneous measurements on each interferometric baseline, with phase differences of 2 between each measurement, allowing complex visibility measurements (modulus

Brian Kern; Paul E. Dimotakis; Chris Martin; Daniel B. Lang; Rachel N. Thessin

2005-01-01

258

Microwave Interferometer Density Diagnostic for the Levitated Dipole Experiment  

E-print Network

a multi-channel microwave interferometer. Such a device makes use the relationship between a plasma's density and its index of refraction. The beams of an interferometer acquire a phase-shift when traversing Oscillator (LO), is mixed with the RF to produce an Intermediate Frequency (IF). · Our interferometer uses

259

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

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

260

Orbiting stellar interferometer for astrometry and imaging.  

PubMed

The orbiting stellar interferometer (OSI) is a concept for a first-generation space interferometer with astrometric and imaging goals and is responsive to the recommendations of the Astronomy and Astrophysics Survey Committee for an astrometric interferometer mission. The OSI, as developed at the Jet Propulsion Laboratory over the past several years, is a triple Michelson interferometer with articulating siderostats and optical delay lines. Two point designs for the instrument are described.

The 18-m design uses an 18-m maximum baseline and aperture diameters of 40 cm; the targeted astrometric performance is a wide-field accuracy of 10 microarsec for 16-mag objects in 100 s of integration time and for 20-mag objects in 1 h. The instrument would also be capable of synthesis imaging with a resolution of 5 marcsec, which corresponds to the diffraction limit of the 18-m base line. The design uses a deployed structure, which would fold to fit into an Atlas HAS shroud, for insertion into a 900-km sun-synchronous orbit In addition to the 18-m point design a 7-m point design that uses a shorter base line in order to simplify deployment is also discussed. OSI's high performance is made possible by utilizing laser metrology and controlled-optics technology.

PMID:20820313

Colavita, M M; Shao, M; Rayman, M D

1993-04-01

261

Accurate radio positions with the Tidbinbilla interferometer  

NASA Technical Reports Server (NTRS)

The Tidbinbilla interferometer, designed specifically to provide accurate radio position measurements of compact radio sources in the Southern Hemisphere with high sensitivity using the 26 m and 64 m antennas of the Deep Space Network at Tidbinbilla, near Canberra, is discussed. The instrument also provides high accuracy flux density measurements for compact radio sources.

Batty, M. J.; Jauncey, D. J.; Rayner, P. T.; Gulkis, S.

1980-01-01

262

Achromatic interferometer for imaging through turbulence  

Microsoft Academic Search

It is shown that the single-aperture grating interferometer produces a deep achromatic fringe field that yields information on the source separation of a two-point source; the intensity ratio between the two points, also, can be ascertained. The primary value of this method lies in the field of application to objects of greater complexity than can be addressed by such simpler

Hsuan Chen; Lian Shentu

1992-01-01

263

A Microwave Interferometer on an Air Track.  

ERIC Educational Resources Information Center

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)

Polley, J. Patrick

1993-01-01

264

Laser wavemeter with solid Fizeau wedge interferometer  

Microsoft Academic Search

A Fizeau wavemeter using a solid Fizeau wedge interferometer that is suitable for determining the wavelength of pulsed or CW laser light has been modeled and investigated experimentally. Accuracy of a few parts in 10 to the 6th over a wide wavelength range can be achieved with careful design. Experimental accuracy of 2 parts in 10 to the 6th was

Christopher Reiser; R. B. Lopert

1988-01-01

265

Low Coherence Vibration Insensitive Fizeau Interferometer  

Microsoft Academic Search

An on-axis, vibration insensitive, polarization Fizeau interferometer is realized through the use of a novel pixelated mask spatial carrier phase shifting technique in conjunction with a low coherence source and a polarization delay-line. In this arrangement, coherence is used to effectively separate out the orthogonally polarized test and reference beam components for interference. With both the test and the reference

Brad Kimbrough; James Millerd; James Wyant; John Hayes

2006-01-01

266

Fizeau interferometer profiles at finite acceptance angles  

Microsoft Academic Search

Instrument profiles of the wedge or Fizeau interferometer are determined under practical conditions. The appearance of subsidiary maxima on the high order side of the central maxima is confirmed, and the behaviour of these is noted as the solid angle of acceptance is varied. From these calculations it is inferred that the acceptable range of use of the instrument could

T A Hall

1969-01-01

267

Ramsey-Bordé interferometer for electrons  

NASA Astrophysics Data System (ADS)

A scheme to realize an electron interferometer using low-intensity, bichromatic laser pulses as beam splitter is proposed. The splitting process is based on a modification of the Kapitza-Dirac effect, which produces a momentum kick for electrons with a specific initial momentum. A full interferometric setup in Ramsey-Bordé configuration is theoretically analyzed.

Marzlin, Karl-Peter

2013-10-01

268

The Green Bank Interferometer Control Frank Ghigo  

E-print Network

Jansky Lab control rooms 2 #12; New Control System Hardware #15; Control Computer #15; Telescope; Monitor system #15; Data logger system #15; User interfaces #15; Support libraries 15 #12; The Green Bank Interferometer Control System John Ford Frank Ghigo 1 #12; The new hardware

Groppi, Christopher

269

Theory of fractional quantum Hall interferometers  

NASA Astrophysics Data System (ADS)

Interference of fractionally charged quasiparticles is expected to lead to Aharonov-Bohm oscillations with periods larger than the flux quantum. However, according to the Byers-Yang theorem, observables of an electronic system are invariant under an adiabatic insertion of a quantum of singular flux. We resolve this seeming paradox by considering a microscopic model of electronic interferometers made from a quantum Hall liquid at filling factor 1/m with the shape of a Corbino disk. In such interferometers, the quantum Hall edge states are utilized in place of optical beams, the quantum point contacts play the role of beam splitters connecting different edge channels, and Ohmic contacts represent a source and drain of quasiparticle currents. Depending on the position of Ohmic contacts, one distinguishes interferometers of Fabry-Pérot (FP) and Mach-Zehnder (MZ) type. An approximate ground state of such interferometers is described by a Laughlin-type wave function, and low-energy excitations are incompressible deformations of this state. We construct a low-energy effective theory by restricting the microscopic Hamiltonian of electrons to the space of incompressible deformations and show that the theory of the quantum Hall edge so obtained is a generalization of a chiral conformal field theory. In our theory, a quasiparticle tunneling operator is found to be a single-valued function of tunneling point coordinates, and its phase depends on the topology determined by the positions of Ohmic contacts. We describe strong coupling of the edge states to Ohmic contacts and the resulting quasiparticle current through the interferometer with the help of a master equation. We find that the coherent contribution to the average quasiparticle current through MZ interferometers does not vanish after summation over quasiparticle degrees of freedom. However, it acquires oscillations with the electronic period, in agreement with the Byers-Yang theorem. Importantly, our theory does not rely on any ad hoc constructions, such as Klein factors, etc. When the magnetic flux through an FP interferometer is varied with a modulation gate, current oscillations have the quasiparticle periodicity, thus allowing for spectroscopy of quantum Hall edge states.

Levkivskyi, Ivan P.; Fröhlich, Jürg; Sukhorukov, Eugene V.

2012-12-01

270

The millimeter-wave bolometric interferometer  

NASA Astrophysics Data System (ADS)

The Millimeter-wave Bolometric Interferometer (MBI) is a technology demonstrator for future searches for the B-mode polarization of the Cosmic Microwave Background (CMB). If observed, B-modes would be a direct probe of the energy scale of inflation, an energy scale that is impossible to reach with even the most sophisticated particle accelerators. In this thesis, I outline the technology differences between MBI and conventional interferometers, including the Faraday effect phase modulators (FPM) used both to control systematic effects and to allow for phase sensitive detection of signals. MBI is a four element adding interferometer with a Fizeau optical beam combiner. This allows simple scaling of the instrument to a large numbers of baselines without requiring complicated pair-wise correlations of signals. Interferometers have an advantage over imaging telescopes when measuring the CMB power spectrum as each baseline is sensitive to a single Fourier mode (angular scale) on the sky. Recovering individual baseline information with this combination scheme requires phase modulating the signal from each antenna. MBI performs this modulation with Faraday effect phase modulators. In these novel cryogenic devices a modulated magnetic field switches the phase of a millimeter-wave RF signal by +/- 90 degrees at frequencies up to a few Hertz. MBI's second season of observations occurred in the winter of 2009 at Pine Bluff Observatory a few miles west of Madsion, WI. We successfully observed interference fringes of a microwave test source located in the far field of the instrument that agree well with those expected from simulations. MBI has inspired a second generation bolometric interferometer, QUBIC, which will have hundreds of antennas and thousands of detectors. When it deploys in 2015, it will be sensitive enough to search for B-mode signals from the CMB.

Gault, Amanda Charlotte

271

Measuring the wavefront distortion of a phased-array laser radar by using a real-time optoelectronic measurement system  

NASA Astrophysics Data System (ADS)

A real-time optoelectronic measurement system is proposed to measure the wavefront distortions of scanning beams of a phased-array laser radar. This measurement system includes electric control rotating and translating platforms and a cyclic radial shearing interferometer(CRSI). CRSI is an effective interferometry to mesure the laser wavefront. A inversion algorithm is used to precisely reconstruct wavefront phase distribution from interferograms generated by the CRSI. An actual experiment of laser wavefront distortion measurement is implemented successfully. The experimental results show that this optoelectromic measurement system can measure laser wavefront distortion of a phased-array laser radar in accuracy and in real time.

Zheng, Chunyan; Wu, Jian

2009-11-01

272

State-labeling Wannier-Stark atomic interferometers  

NASA Astrophysics Data System (ADS)

Using cold 87Rb atoms trapped in a one-dimensional (1D)-optical lattice, atomic interferometers involving coherent superpositions between different Wannier-Stark atomic states are realized. Two different kinds of trapped interferometer schemes are presented: a Ramsey-type interferometer sensitive both to clock frequency and external forces, and a symmetric accordion-type interferometer, sensitive to external forces only. We evaluate the limits in terms of sensitivity and accuracy of those schemes and discuss their application as force sensors. As a first step, we apply these interferometers to the measurement of the Bloch frequency and the demonstration of a compact gravimeter.

Pelle, B.; Hilico, A.; Tackmann, G.; Beaufils, Q.; Pereira dos Santos, F.

2013-02-01

273

METR 4624--Radar Meteorology SPRING 2014  

E-print Network

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

Droegemeier, Kelvin K.

274

MIMO Radar with Widely Separated Antennas  

Microsoft Academic Search

MIMO (multiple-input multiple-output) radar refers to an architecture that employs multiple, spatially distributed transmitters and receivers. While, in a general sense, MIMO radar can be viewed as a type of multistatic radar, the separate nomenclature suggests unique features that set MIMO radar apart from the multistatic radar literature and that have a close relation to MIMO communications. This article reviews

Alexander Haimovich; Rick Blum; Leonard Cimini

2008-01-01

275

METR 4624--Radar Meteorology SPRING 2012  

E-print Network

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

Droegemeier, Kelvin K.

276

An MSK Radar Waveform  

NASA Technical Reports Server (NTRS)

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.

Quirk, Kevin J.; Srinivasan, Meera

2012-01-01

277

Investigation of Space Interferometer Control Using Imaging Sensor Output Feedback  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

278

Investigation of Space Interferometer Control Using Imaging Sensor Output Feedback  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

279

P15R.1 THE DETECTABILITY OF TORNADIC SIGNATURES WITH DOPPLER RADAR: A RADAR EMULATOR STUDY  

E-print Network

P15R.1 THE DETECTABILITY OF TORNADIC SIGNATURES WITH DOPPLER RADAR: A RADAR EMULATOR STUDY Ryan M the operation of a radar, using a software radar emulator, one can artificially generate large data sets describes a radar emulator designed to simulate the returns from a scanning Doppler radar on a pulse

Xue, Ming

280

Laser-Ranging Long Baseline Differential Atom Interferometers for Space  

E-print Network

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

Chiow, Sheng-wey; Yu, Nan

2015-01-01

281

Quantum metrology with parametric amplifier-based photon correlation interferometers  

PubMed Central

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

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

2014-01-01

282

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

283

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

284

Polarization radar processing technology  

NASA Astrophysics Data System (ADS)

A comprehensive effort involving measurements and performance evaluation for the detection of scatterers immersed in a background of natural and man-made clutter using polarization diverse waveforms is presented. The effort spans evaluation from the initial stages of theoretical formation to processor performance evaluation using real-world data. The theoretical approach consists of determining polarimetric statistical properties of the backscatter waveform and these properties to derive the optimum dual-polarized S-band radar system with selectable polarization on both transmit and receive. Several processors utilizing optimum and suboptimum algorithms were evaluated using simulated and live radar data, and performance results are compared. The processor types include fully adaptive algorithms designed to operate on polarimetric spectral spread waveforms, and several combinations of single channel and polarization diverse receivers with both single and dual transmit polarization. Results are plotted and evaluated by displaying probability of detection as a function of signal-to-noise ratio with processor type as a parameter.

Wicks, Michael C.; Vannicola, Vincent C.; Stiefvater, Kenneth C.; Brown, Russell D.

285

RADAR Reveals Titan Topography  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

286

Imaging synthetic aperture radar  

DOEpatents

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.

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

1997-01-01

287

Shuttle imaging radar experiment  

USGS Publications Warehouse

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

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

1982-01-01

288

Polarization diversity in radars  

Microsoft Academic Search

Many polarization techniques, which have been proposed and analyzed to enhance radar performance, are reviewed in this paper in order to assess the possible improvement they can provide in the signal-to-disturbance ratio, target detectability, target discrimination and resolution, and target classification and identification. Some recent experimentally-based results relating to these applications are also presented. Those techniques are emphasized for which

D. Giuli

1986-01-01

289

Radar Imagery of Mercury  

NASA Astrophysics Data System (ADS)

Radar observations of Mercury have yielded important results including the discovery of the 3:2 spin:orbit resonance [1] discovery of distinct large surface roughness features [2] measurement of the perihelion advance (as a test of general relativity) [3] ephemeris improvements [4] information on shape [5] topography [6] and more recent constraints on the spin and orbit state [7]. But perhaps the most stunning discoveries have come from mapping experiments made possible by the Goldstone/VLA radarand improvements in the Random Long Code techniques in monostatic experiments [8]. These experiments provide maps of radar reflectivity across most of the visible disk of the planet and have been used to infer the presence of polar ices and large fresh impact craters among other features [9]. We will present a summary of the knowledge gained from these radar mapping observations recent results and plans for future experiments. [1] Dyce et al. 1967. [2] Zohar & Goldstein 1974. [3] Anderson et al. 1991. [4] Jurgens et al. 1998. [5] Anderson et al. 1996. [6] Harmon et al. 1986; Slade et al. 1997. [7] Margot et al. 2002. [8] Muhleman et al. 1995; Harmon 2002. [9] Butler et al. 1993; Harmon et al. 2001; Harmon 1997.

Butler, Bryan J.; Harmon, John K.; Slade, Martin A.

290

Comet radar explorer  

NASA Astrophysics Data System (ADS)

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

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

291

Intrapulse Radar-Embedded Communications  

Microsoft Academic Search

The embedding of a covert communication signal amongst the ambient scattering from an incident radar pulse has previously been achieved by modulating a Doppler-like phase shift sequence over numerous pulses (i.e., on an inter-pulse basis). In contrast, this paper considers radar-embedded communications on an intrapulse basis whereby an incident radar waveform is converted into one of $K$ communication waveforms, each

Shannon D. Blunt; Padmaja Yatham; James Stiles

2010-01-01

292

RF MEMS on the radar  

Microsoft Academic Search

This article gives an overview of applications of radio frequency (RF) microelectromechanical system (MEMS) technology in radio detection and ranging (radar). RF MEMS components for radar include attenuators, limiters, (true-time-delay) phase shifters, transmit\\/receive (T\\/R) switches and tunable matching networks. Radar subsystems that benefit from RF MEMS technology include active electronically scanned arrays (T\\/R modules), passive electronically scanned arrays (lenses, reflect

Koen Van Caekenberghe

2009-01-01

293

Radar-aeolian roughness project  

NASA Technical Reports Server (NTRS)

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.

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

294

Radar studies of bird migration  

NASA Technical Reports Server (NTRS)

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.

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

1974-01-01

295

47 CFR 80.273 - Radar standards.  

Code of Federal Regulations, 2013 CFR

...Telecommunication 5 2013-10-01 2013-10-01 false Radar standards. 80.273 Section 80.273 Telecommunication...Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar installations on board ships that are...

2013-10-01

296

47 CFR 80.273 - Radar standards.  

Code of Federal Regulations, 2012 CFR

...Telecommunication 5 2012-10-01 2012-10-01 false Radar standards. 80.273 Section 80.273 Telecommunication...Authorization for Compulsory Ships § 80.273 Radar standards. (a) Radar installations on board ships that are...

2012-10-01

297

Overview of Radar Data Compression Valliappa Lakshmanan  

E-print Network

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

Lakshmanan, Valliappa

298

REVIEW ARTICLE Interferometric Synthetic Aperture Radar  

E-print Network

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

Kansas, University of

299

Reconfigurable L-Band Radar  

NASA Technical Reports Server (NTRS)

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.

Rincon, Rafael F.

2008-01-01

300

Soliton-based matter-wave interferometer  

NASA Astrophysics Data System (ADS)

We consider a matter-wave bright soliton interferometer composed of a harmonic potential trap with a Rosen-Morse barrier at its center on which an incident soliton collides and splits into two solitons. These two solitons recombine after a dipole oscillation in the trap at the position of the barrier. We focus on the characterization of the splitting process in the case in which the reflected and transmitted solitons have the same number of atoms. We obtain that the velocity of the split solitons strongly depends on the nonlinearity and on the width of the barrier and that the reflected soliton is in general slower than the transmitted one. Also, we study the phase difference acquired between the two solitons during the splitting and we fit semianalytically the main dependences with the velocity of the incident soliton, the nonlinearity, and the width of the barrier. The implementation of the full interferometer sequence is tested by means of the phase imprinting method.

Polo, J.; Ahufinger, V.

2013-11-01

301

Accurate radio positions with the Tidbinbilla interferometer  

NASA Technical Reports Server (NTRS)

The Tidbinbilla interferometer (Batty et al., 1977) is designed specifically to provide accurate radio position measurements of compact radio sources in the Southern Hemisphere with high sensitivity. The interferometer uses the 26-m and 64-m antennas of the Deep Space Network at Tidbinbilla, near Canberra. The two antennas are separated by 200 m on a north-south baseline. By utilizing the existing antennas and the low-noise traveling-wave masers at 2.29 GHz, it has been possible to produce a high-sensitivity instrument with a minimum of capital expenditure. The north-south baseline ensures that a good range of UV coverage is obtained, so that sources lying in the declination range between about -80 and +30 deg may be observed with nearly orthogonal projected baselines of no less than about 1000 lambda. The instrument also provides high-accuracy flux density measurements for compact radio sources.

Batty, M. J.; Gulkis, S.; Jauncey, D. L.; Rayner, P. T.

1979-01-01

302

Bright solitonic matter-wave interferometer.  

PubMed

We present the first realization of a solitonic atom interferometer. A Bose-Einstein condensate of 1×10(4) atoms of rubidium-85 is loaded into a horizontal optical waveguide. Through the use of a Feshbach resonance, the s-wave scattering length of the 85Rb atoms is tuned to a small negative value. This attractive atomic interaction then balances the inherent matter-wave dispersion, creating a bright solitonic matter wave. A Mach-Zehnder interferometer is constructed by driving Bragg transitions with the use of an optical lattice colinear with the waveguide. Matter-wave propagation and interferometric fringe visibility are compared across a range of s-wave scattering values including repulsive, attractive and noninteracting values. The solitonic matter wave is found to significantly increase fringe visibility even compared with a noninteracting cloud. PMID:25032924

McDonald, G D; Kuhn, C C N; Hardman, K S; Bennetts, S; Everitt, P J; Altin, P A; Debs, J E; Close, J D; Robins, N P

2014-07-01

303

Bright Solitonic Matter-Wave Interferometer  

NASA Astrophysics Data System (ADS)

We present the first realization of a solitonic atom interferometer. A Bose-Einstein condensate of 1×104 atoms of rubidium-85 is loaded into a horizontal optical waveguide. Through the use of a Feshbach resonance, the s-wave scattering length of the Rb85 atoms is tuned to a small negative value. This attractive atomic interaction then balances the inherent matter-wave dispersion, creating a bright solitonic matter wave. A Mach-Zehnder interferometer is constructed by driving Bragg transitions with the use of an optical lattice colinear with the waveguide. Matter-wave propagation and interferometric fringe visibility are compared across a range of s-wave scattering values including repulsive, attractive and noninteracting values. The solitonic matter wave is found to significantly increase fringe visibility even compared with a noninteracting cloud.

McDonald, G. D.; Kuhn, C. C. N.; Hardman, K. S.; Bennetts, S.; Everitt, P. J.; Altin, P. A.; Debs, J. E.; Close, J. D.; Robins, N. P.

2014-07-01

304

Adaptive DFT-based Interferometer Fringe Tracking  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

305

Digital array scanned interferometers for astronomy  

NASA Technical Reports Server (NTRS)

Investigations are reported of digital array scanned interferometers (DASI) with silicon CCD array detectors to define the operational capabilities of a mapping (polarimetric) spectrometer for astronomical applications based on these instruments. For spectral mapping, spatially resolved spectra using a cylindrical lens to image in the interferometers's redundant coordinate are given. The signal-to-noise characteristics of the Fourier transformed data are demonstrated with regard to the effects of a rectangular sampling function, spectral multiplexing and the pixel-to-pixel variation of the CCD array. These data indicate that DASIs can offer simple, versatile (polarization) mapping spectrometers suitable for spectral mapping observations from the ultraviolet to the infrared of extended sources at variable spatial resolution, particularly where long term stable operation is essential, as for spacecraft instruments.

Smith, Wm. Hayden; Schempp, W. V.

1991-01-01

306

A stellar interferometer on the Moon  

NASA Astrophysics Data System (ADS)

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. Th

Porro, Irene

307

Interferometer for Low-Uncertainty Vector Metrology  

NASA Technical Reports Server (NTRS)

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.

Toland, Ronald W.; Leviton, Douglas B.

2006-01-01

308

Analysis of atom-interferometer clocks  

NASA Astrophysics Data System (ADS)

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.

Peil, Steven; Ekstrom, Christopher R.

2014-01-01

309

Cloud Base Height and Effective Cloud Emissivity Retrieval with Ground-Based Infrared Interferometer  

NASA Astrophysics Data System (ADS)

Based on ground-based Atmospheric Emitted Radiance Interferometer (AERI) observations in Shouxian, Anhui province, China, the cloud base height (CBH) and effective cloud emissivity are retrieved by using the minimum root-mean-square difference method. This method was originally developed for satellite remote sensing. The high-temporal-resolution retrieval results can depict the trivial variations of the zenith clouds continuously. The retrieval results are evaluated by comparing them with observations by the cloud radar. The comparison shows that the retrieval bias is smaller for the middle and low clouds, especially for opaque clouds. When two layers of clouds exist, the retrieval results reflect the weighting radiative contribution of the multi-layer cloud. The retrieval accuracy is affected by uncertainties of the AERI radiances and sounding profiles, in which the role of uncertainty in the temperature profile is dominant.

Pan, L.; Lu, D.

2012-12-01

310

Interferometer-Based Adaptive Optical System  

Microsoft Academic Search

Interferometer-based adaptive optics has an advantage of direct measurement of the wavefront profile. Nevertheless the majority\\u000a of adaptive optical systems, realized so far, use other types of wavefront sensors, such as Hartmann sensors. Interferometric\\u000a sensors have two problems: (1) a source of a coherent reference wave should be present and (2) in many cases it is impossible\\u000a to reconstruct the

O. Soloviev; G. Vdovin

311

Large aperture ac interferometer for optical testing.  

PubMed

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

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

1978-12-15

312

Laser wavemeter with solid Fizeau wedge interferometer  

SciTech Connect

A Fizeau wavemeter using a solid Fizeau wedge interferometer that is suitable for determining the wavelength of pulsed or cw laser light has been modeled and investigated experimentally. Accuracy of a few parts in 10/sup 6/ over a wide wavelength range can be achieved with careful design. Experimental accuracy of 2 parts in 10/sup 6/ was demonstrated over a range of 40 nm.

Reiser, C.; Lopert, R.B.

1988-09-01

313

Binaries for the Stellar Interferometer Program  

NASA Astrophysics Data System (ADS)

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.

Kelz, A.

314

Technology of polarization diversity radars for meteorology  

Microsoft Academic Search

Polarimetric techniques and their application to radar meteorology are reviewed. Four state-of-the-art radar systems are described and other dual-polarized radars and their measurement capabilities are also presented. A discussion of radar system considerations is provided. In the review of dual-polarized meteorological radar installations it was found that 21 such radars were currently or recently active, covering the frequency range 3-35

V. N. Bringi; A. Hendry

1990-01-01

315

Monitoring of Active Blazars using DSN Interferometer  

NASA Astrophysics Data System (ADS)

The Large Area Telescope (LAT) instrument on-board the Fermi Gamma-ray Space Telescope, formerly GLAST, has already provided unprecedented views of the gamma-ray sky. The LAT instrument with its high sensitivity, large field of view, and excellent energy and position resolution, offers a unique window for identification and study of high energy processes in blazars. To maximize the science return from the LAT, dedicated and robust multi-wavelength (MW) monitoring campaigns are crucial for identification and especially for understanding the underlying emission mechanisms of these sources. As part of an effort to demonstrate the capabilities of a sensitive radio interferometer, we have carried out a number of pilot observations of a sample of calibrators with a short baseline interferometer operating simultaneously at 2 and 8 GHz using a pair of large DSN antennas in Goldstone, CA. We present the results of these pilot observations, which demonstrate the capability of such a short baseline interferometer to carry out routine monitoring of active blazars, providing complementary information to dedicated monitoring programs using single dish antennas currently in operation. We also discuss the potential of a dedicated monitoring program using two 34-m antennas operated by a K-12 student-run program in Goldstone.

Majid, Walid A.

2010-05-01

316

Fizeau interferometer for global astrometry in space.  

PubMed

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

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

2004-02-01

317

A Study of Imaging Interferometer Simulators  

NASA Technical Reports Server (NTRS)

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.

Allen, Ronald J.

2002-01-01

318

Interferometers as probes of Planckian quantum geometry  

NASA Astrophysics Data System (ADS)

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

Hogan, Craig J.

2012-03-01

319

Photorefractive Interferometers for Ultrasonic Measurements on Paper  

SciTech Connect

Photorefractive interferometers have been employed for the detection of ultrasound in metals and composites since 1991 [1–4]. Instances of laser-generated ultrasound and laser-based detection in paper were reported in 1996 [5]. More recently, bismuth silicon oxide (BSO) photorefractive interferometers were adapted to detect ultrasound in paper [6]. In this article we discuss BSO and GaAs photorefractive detection of ultrasound on different paper grades and present the resulting waveforms. Compared to contact piezoelectric transducer methods, laser interferometry offers signifcant advantages. One of these is that it is a noncontact technique. This is especially important for on-line application to lightweight papers which could be marked or damaged by contact transducers. Broadband ultrasonic laser generation matched with the broadband sensitivity of laser interferometers is another beneft. This is important for obtaining narrow pulses in nondispersive time-of-fight determinations and for measuring the phase velocity of dispersive modes over a wide frequency band. Also, laser ultrasonic techniques provide a measure of bending stiffness through the analysis of low frequency A0 waves.

Lafond, E. F.; Brodeur, P. H.; Gerhardstein, J. P.; Habeger, C. C.; Telschow, Kenneth Louis

2002-12-01

320

Hybrid photonic chip interferometer for embedded metrology  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

321

Tunneling current through fractional quantum Hall interferometers  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

322

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

DOEpatents

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.

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

2008-12-02

323

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

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

324

Ramsey-Bordé interferometer and embedded Ramsey interferometer with molecular matter waves of 39K2  

NASA Astrophysics Data System (ADS)

A matter wave interferometer based on a molecular beam of K2 has been designed for observation of both exits: with molecules in the electronically excited state and in the ground state. In addition to the excited state fluorescence the molecular ground state population is detected with a further laser. Two transitions to different electronic states were employed for this purpose and their usefulness is compared. Under the present experimental conditions both interferometer exits show a superposition of different interference patterns due to the influence of transverse and longitudinal overlaps of the interfering matter waves. The interference patterns have been analyzed to be composed of a contribution caused by a two beam splitter Ramsey interference and Ramsey-Bordé pattern with four beam splitters. This overlap of interference signals influences the suitability of the matter wave interferometer for phase measurements of the interferences.

Liu, S.; Sherstov, I.; Lisdat, C.; Knöckel, H.; Tiemann, E.

2010-06-01

325

Venus - First Radar Test  

NASA Technical Reports Server (NTRS)

After traveling more than 1.5 billion kilometers (948 million miles), the Magellan spacecraft was inserted into orbit around Venus on Aug. 10, 1990. This mosaic consists of adjacent pieces of two Magellan image strips obtained on Aug. 16 in the first radar test. The radar test was part of a planned In Orbit Checkout sequence designed to prepare the Magellan spacecraft and radar to begin mapping after Aug. 31. The strip on the left was returned to the Goldstone Deep Space Network station in California; the strip to the right was received at the DSN in Canberra, Australia. A third station that will be receiving Magellan data is located near Madrid, Spain. Each image strip is 20 km (12 miles) wide and 16,000 km (10,000 miles) long. This mosaic is a small portion 80 km (50 miles) long. This image is centered at 21 degrees north latitude and 286.8 degrees east longitude, southeast of a volcanic highland region called Beta Regio. The resolution of the image is about 120 meters (400 feet), 10 times better than previous images of the same area of Venus, revealing many new geologic features. The bright line trending northwest southeast across the center of the image is a fracture or fault zone cutting the volcanic plains. In the upper left corner of the image, a multiple ring circular feature of probable volcanic origin can be seen, approximately 4.27 km (2.65 miles) across. The bright and dark variations seen in the plains surrounding these features correspond to volcanic lava flows of varying ages. The volcanic lava flows in the southern half of the image have been cut by north south trending faults. This area is similar geologically to volcanic deposits seen on Earth at Hawaii and the Snake River Plains in Idaho.

1990-01-01

326

Equatorial MST radars: Further consideration  

NASA Technical Reports Server (NTRS)

The results presented give additional support to the need of equatorial MST radars in order to obtain more information on the nature of equatorial waves in the MST region. Radar deduced winds such as obtained at Jicamarca for periods of months indicate that with these data the full range of equatorial waves, with time scales of seconds to years, can be studied.

Lagos, P.

1983-01-01

327

Decorrelation in interferometric radar echoes  

Microsoft Academic Search

A radar interferometric technique for topographic mapping of surfaces, implemented utilizing a single synthetic aperture radar (SAR) system in a nearly repeating orbit, is discussed. The authors characterize the various sources contributing to the echo correlation statistics, and isolate the term which most closely describes surficial change. They then examine the application of this approach to topographic mapping of vegetated

Howard A. Zebker; John Villasensor

1992-01-01

328

Wideband radar (advantages and problems)  

Microsoft Academic Search

Review of advantages and problems of wideband radar is given. Some criteria of wideband (UWB) radar are discussed to avoid misunderstanding when only the relative signal bandwidth is used as a criterion. Brief historical outline of the first and follow up experiments by different authors is presented. Advantages and disadvantages of bandwidth widening can be compared using the computer simulation

Y. D. Shirman; S. P. Leshchenko; V. M. Orlenko

2004-01-01

329

Interception of LPI radar signals  

Microsoft Academic Search

The interception problem is reviewed, an LPI radar design is examined and the performance of intercept receivers of the future is considered. The receiver needed to intercept LPI signals must respond across a broad band and provide noncoherent integration capabilities over times comparable to the coherent (or noncoherent) integration times used by radars. One useful receiver design is the rapidly

Gerd Schrick; R. G. Wiley

1990-01-01

330

Waveform diversity in distributed radar  

Microsoft Academic Search

The desire to anticipate actions before they occur is a goal within the military. Cognitive sensor and communications systems along with distributed radar systems are key enablers to meet this need. Close in sensing examples are provided showing the value of waveform diversity in distributed radar. The use of waveform diversity presents a challenge to the electromagnetic compatibility (EMC) community.

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

2009-01-01

331

Frequency diversity in multistatic radars  

Microsoft Academic Search

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

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

2008-01-01

332

Glacio RADAR system and results  

Microsoft Academic Search

Since 1997 the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Italy has been involved in the development of the airborne RES system named Glacio RADAR, which is continuously upgraded. Radio Echo Sounding (RES) techniques are widely used in glaciological measurements. They are based on the use of radar systems, to obtain information concerning ice thickness of ice sheets and

A. Zirizzotti; J. A. Baskaradas; C. Bianchi; U. Sciacca; I. E. Tabacco; E. Zuccheretti

2008-01-01

333

CURRENT APPLICATIONS OF IMAGING RADAR  

Microsoft Academic Search

This paper discusses the current status of imaging radar systems deployed on spacecraft and airborne platforms, such as aircraft and unmanned airborne vehicles (UAVs). Imaging radar technology has advanced considerably over the last twenty years, and the user can now be fairly certain of finding a sensor ideal for a specifi c application. The objective of the paper is to

M. R. Inggs; R. T. Lord; WG VII

334

Gravitational Wave Detection with Single-Laser Atom Interferometers  

NASA Technical Reports Server (NTRS)

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.

Yu, Nan; Tinto, Massimo

2011-01-01

335

Special topics in infrared interferometry. [Michelson interferometer development  

NASA Technical Reports Server (NTRS)

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.

Hanel, R. A.

1985-01-01

336

Optical guided-wave gallium arsenide monolithic interferometer  

NASA Astrophysics Data System (ADS)

A guided-wave interferometer capable of modulating 1.3-micron radiation via the electro-optic effect has been fabricated in GaAs. The interferometer uses three-guide couplers as the input and output sections and single-mode slab-coupled p(+)-n(-)-n(+) rib waveguides fabricated by means of Be-ion implantation for the two active arms. An extinction of approximately 14.5 dB of the output signal from the center guide is obtained with 22 V applied to one arm of the interferometer. Interferometers of this type should be capable of large signal modulation out to 5-10 GHz.

Donnelly, J. P.; Demeo, N. L.; Ferrante, G. A.; Nichols, K. B.; Odonnell, F. J.

1984-08-01

337

Software Radar Technology and the Open Radar Initiative  

NASA Astrophysics Data System (ADS)

We have recently implemented a Software Radar System as the production data taking and control system for the Millstone Hill Incoherent Scatter Radar. In a Software Radar the traditional real-time hardware control and signal processing elements of a radar system are replaced by software systems running on general purpose computer systems and interconnected by a high speed and low latency multicast network. From our efforts to develop this system we have identitified a number of architectural patterns which are important for achieving performance, modularity, and scalability in distributed systems for managing experimental instrumentation and the many terabytes of information that are produced. The most important of these patterns concern information organization and management in the system and they are general far beyond their application to ionospheric radar systems. After discussing our system and these patterns we will describe the Open Radar Initiative. This effort is an open source project to make Software Radar technology widely available and to ready it for use as the foundation of a ground based Global Space Weather Network.

Lind, F. D.; Grydeland, T.; Erickson, P. J.; Rideout, B.; Holt, J.

2002-12-01

338

Coherent backscatter radar imaging in Brazil: Bottomside radar plumes  

NASA Astrophysics Data System (ADS)

The 30 MHz coherent scatter backscatter radar in Sao Luis, Brazil has been used for routine two-antenna observations of equatorial E and F region field aligned irregularities since 2002. In 2005, two antenna modules were added to the already existing two modules. These new modules would allow observations with 6 independent interferometric baselines, which then could be used for construction of in-beam radar images similar to those produced at Jicamarca Radio Observatory [e.g. Hysell, 1996]. Despite the low transmitting power and reduced number of baselines, in-beam radar images of F-region scattering structures were successfully constructed with the Sao Luis radar observations. Initial imaging results were used to investigate the horizontal structure of a bottom-type scattering that preceded a fully developed radar plume [Rodrigues et al., 2009]. Here, we examine Sao Luis observations of bottomside radar plumes. Details of the observations and analysis will be presented and the characteristics of the scattering structures seen with this radar will be discussed.

Rodrigues, F. S.; de Paula, E. R.; Hysell, D. L.

2010-12-01

339

Mars Radar Observations with the Goldstone Solar System Radar  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

340

Measuring Cyclic Error in Laser Heterodyne Interferometers  

NASA Technical Reports Server (NTRS)

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-

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

2010-01-01

341

Understanding Radar Refractivity: Sources of Uncertainty  

E-print Network

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

Droegemeier, Kelvin K.

342

FIRE_CI2_ETL_RADAR  

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

2014-05-06

343

Navigation radar signal acquisition and measurement system  

Microsoft Academic Search

In the course of navigation, radar is a very important navigation aids. However, different types of radar always have different signal definition. In this paper, a kind of method on radar signal acquisition and measurement based on embedded system is proposed. The system, which could automatically detect some common radar signal parameter, is consist of CPLD, ARM micro processor, ADC

Shaowei Li; Xinqing Zhuang

2009-01-01

344

Advanced ground-based ESCAN radars  

Microsoft Academic Search

Electronically scanned radars (ESCAN radars) are key system elements of ground based military systems being developed for air and missile defense against future threats including tactical ballistic missiles, high agile and low RCS targets like drones, ARMs, UAVs. The radar design is governed on the one hand by challenging requirements on ESCAN radar performance and on the other hand by

U. Fuchs; W. Sieprath

2005-01-01

345

Talbot interferometer for radial and lateral derivatives.  

PubMed

The theory and experimental evidence of a shearing interferometer based on the Talbot effect are presented. Multiple-shearing interferences are obtained that can be reduced to triple-shearing or doubleshearing interferences by the addition of simple spatial filtering. When the shear is less than the width of the details in the object, these interferences become either the second or first derivative of the object under test, respectively. Either lateral or constant radial shear can be introduced by choosing Ronchi rulings or circular gratings. Thus both lateral and radial derivatives are easily obtained. If white light is used as a source, color fringes of high contrast are observed. PMID:20119380

Silva, D E

1972-11-01

346

Controller of the Laser Interferometer Space Antenna  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

347

Aperture correction for a sphere interferometer  

NASA Astrophysics Data System (ADS)

Considerations have been made to derive a correction for the diameter measurements of a sphere by means of a special sphere interferometer. This correction is caused by the finite diameter of the light source acting as the entrance 'pinhole' aperture in the light collimating system. The finite diameter has the effect that the wave which is incident on the sphere is a superposition of spherical waves which are slightly inclined with respect to each other. The resulting correction is essential for high accuracy dimensional measurements of silicon spheres to determine the Avogadro constant—a new determination of which is a contribution to a new definition of the kilogram.

Arnold Nicolaus, R.; Bönsch, Gerhard

2009-12-01

348

Micro-Precision Interferometer: Pointing Control System  

NASA Technical Reports Server (NTRS)

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.

O'Brien, John

1995-01-01

349

Interferometer observations of RS Canum Venaticorum binaries  

NASA Astrophysics Data System (ADS)

We present radio flux measurements at 5 GHz for a sample of RS CVn-type chromospherically active binary systems made from 1988 to 1992 using the Nuffield Radio Astronomy Laboratories (NRAL) broad-band interferometer (BBI). The derived radio luminosities are consistent with previous observations but show that radio flaring is a common feature which will effect the results of rotation-activity studies. The mean brightness temperature for our sample, assuming a radio source size equal to twice the radius of the active stellar component, is consistent with a gyrosynchrotron emission process from mildly relativistic electrons.

Gunn, A. G.; Spencer, R. E.; Abdul Aziz, H.; Doyle, J. G.; Davis, R. J.; Pavelin, P. E.

1994-11-01

350

Mach-Zehnder interferometer for movement monitoring  

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

351

Laser diode in a coherent resolved interferometer  

NASA Astrophysics Data System (ADS)

A short coherence length of a laser diode (LD) is required in coherent resolved interferometers. The coherence length of a LD can be reduced by modulating the source with a high frequency signal, which is superposed on the driving current for the LD. A 980nm laser diode in this paper is modulated with a frequency 40MHz and modulation depth 0.5, where its coherence length is compressed 20 times. The first side-band peak in the coherence function is reduced by 10dB, but it is hard to suppress them completely.

Sun, Dongsong; Liu, Shigang; Zhao, Yuan; Qiao, Lijie

1996-09-01

352

Modified Phasemeter for a Heterodyne Laser Interferometer  

NASA Technical Reports Server (NTRS)

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.

Loya, Frank M.

2010-01-01

353

Large phased-array radars  

SciTech Connect

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.

Brookner, D.E.

1988-12-15

354

A Bistatic Parasitical Radar (BIPAR)  

NASA Astrophysics Data System (ADS)

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.

Hartl, Philipp; Braun, Hans Martin

1989-01-01

355

Space Radar Images of Earth  

NSDL National Science Digital Library

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

356

The Clementine bistatic radar experiment  

USGS Publications Warehouse

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.

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

1996-01-01

357

Nonadaptive MIMO radar techniques for reducing clutter  

Microsoft Academic Search

Multiple-Input, Multiple-Output (MIMO) radars enhance performance by transmitting and receiving coded waveforms from multiple locations. This paper describes how MIMO techniques can be used to improve radar performance, especially in airborne GMTI applications. A previous analysis of the clutter-to-noise-ratio (CNR) for stationary, surface-based MIMO radar is extended to the airborne radar scenario. Our analysis shows that MIMO airborne radars will

Daniel J. Rabideau; Lexington MA

2008-01-01

358

Historical aspects of radar atmospheric dynamics  

NASA Technical Reports Server (NTRS)

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.

Kato, Susumu

1989-01-01

359

An Imaging Interferometer for Terrestrial Remote Sensing  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

360

CIRRIS-1A interferometer: radiometric analysis.  

PubMed

The CIRRIS-lA spectroradiometer system is designed to obtain spectral and spatial airglow data on the shuttle platform over a global extent. The sensor system includes a Michelson interferometer which exhibits a noise equivalent sterance [radiance] (NER) of 2 x 10(-13) W cm(-2) sr(-1) Hz(-1/2); and at a resolution of 0.964 cm(-1) (scan time 9.1 s) exhibits a noise equivalent spectral sterance [radiance] NESR of 7 x 10(-14) W cm(-2)sr(-1)/cm(-1). The entire optical subsystem, silicon-arsenic focal-plane, off-axis high-rejection telescope, and removable cover are cooled below 20 K. The measured performance is shown to agree with theory to within a few percent. Noise-equivalent-sterance [radiance] per root-Hz is recommended as a figure of merit for interferometers that is independent of the specific operating conditions; i.e., mirror velocity, scan time or transform size. PMID:20556001

Wyatt, C L

1989-12-01

361

Ultraviolet-Infrared Mapping Interferometic Spectrometer  

NASA Technical Reports Server (NTRS)

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.

1994-01-01

362

Retrievals with the Infrared Atmospheric Sounding Interferometer  

NASA Technical Reports Server (NTRS)

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.

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

363

Radar backscatter modelling  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

364

Modes in a maser interferometer with curved and tilted mirrors  

Microsoft Academic Search

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

A. G. Fox; Tingye Li

1963-01-01

365

Fiber-optic interferometer for remote subangstrom vibration measurement  

NASA Astrophysics Data System (ADS)

A single-mode fiber-optic interferometer for measuring subangstrom vibrations has been designed and constructed. The interferometer is based on the Fizeau configuration and employs peak detection schemes in the signal processing. The instrument has been used to measure the displacement of a cricket's tympanic membrane.

Drake, Allen Dean; Leiner, Dennis C.

1984-02-01

366

Michelson interferometer based interleaver design using classic IIR filter decomposition.  

PubMed

An elegant method to design a Michelson interferometer based interleaver using a classic infinite impulse response (IIR) filter such as Butterworth, Chebyshev, and elliptic filters as a starting point are presented. The proposed design method allows engineers to design a Michelson interferometer based interleaver from specifications seamlessly. Simulation results are presented to demonstrate the validity of the proposed design method. PMID:24514708

Cheng, Chi-Hao; Tang, Shasha

2013-12-16

367

Numerical simulation and experimental verification of extended source interferometer  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

368

Fiber-optic interferometer using frequency-modulated laser diodes  

NASA Technical Reports Server (NTRS)

This paper describes an electrically passive fiber-optic interferometer which uses dual frequency-modulated laser diodes. Experimental results show that this type of interferometer can attain a displacement range of 100 micron with subnanometer resolution. This technique can serve as the basis for a number of high-precision fiber-optic sensors.

Beheim, G.

1986-01-01

369

Silicon Carbide Mounts for Fabry-Perot Interferometers  

NASA Technical Reports Server (NTRS)

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.

Lindemann, Scott

2011-01-01

370

Polarization Sagnac interferometer with a common-path  

E-print Network

Polarization Sagnac interferometer with a common-path local oscillator for heterodyne detection, Stanford, California 94305 Received January 5, 1999 We describe a free-space common-path polarization Sagnac interferometer. The polarization Sagnac interfer- ometer is used in a symmetric fashion

Byer, Robert L.

371

Imaging interferometer using dual broadband quantum well infrared photodetectors  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

372

Surface figure measurements of radio telescopes with a shearing interferometer  

Microsoft Academic Search

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

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

1991-01-01

373

Extraction of energy from gravitational waves by laser interferometer detectors  

NASA Astrophysics Data System (ADS)

In this paper, we discuss the energy interaction between gravitational waves and laser interferometer gravitational wave detectors. We show that the widely held view that the laser interferometer gravitational wave detector absorbs no energy from gravitational waves is only valid under the approximation of a frequency-independent optomechanical coupling strength and a pump laser without detuning with respect to the resonance of the interferometer. For a strongly detuned interferometer, the optical-damping dynamics dissipates gravitational wave energy through the interaction between the test masses and the optical field. For a non-detuned interferometer, the frequency-dependence of the optomechanical coupling strength causes a tiny energy dissipation, which is proved to be equivalent to the Doppler friction raised by Braginsky et al.

Ma, Yiqiu; Blair, David G.; Zhao, Chunnong; Kells, William

2015-01-01

374

Dispersion interferometer using modulation amplitudes on LHD (invited)  

SciTech Connect

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.

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

2014-11-15

375

Radar imaging of Saturn's rings  

Microsoft Academic Search

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

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

2005-01-01

376

The NASA Polarimetric Radar (NPOL)  

NASA Technical Reports Server (NTRS)

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

Petersen, Walter A.; Wolff, David B.

2013-01-01

377

LPI considerations for surveillance radars  

Microsoft Academic Search

A low probability-of-intercept (LPI) radar is designed for covert operations which uses minimum radiated power and measures target characteristics with a waveform modulation that is difficult for an intercept receiver to identify. It is established that while doubling the number of an LPI radar's receivers improves the LPI factor by 3 dB, it increases cost by a factor of 2.

L. I. Ruffe; G. F. Stott

1992-01-01

378

Simulation of orbital radar images  

NASA Technical Reports Server (NTRS)

The operating parameters for spaceborne synthetic aperture imaging radar systems was addressed in the cost effective manner by using simulation techniques. The use of airborne images, Seasat images, and computer simulation were the first computer simulation of spaceborne radar imagery was analyzed for system definition studies. Analysis of the simulation indicates that incidence angles as small as 30 are useful for general terrain geomorphologic analysis.

Saunders, R. S.; Holtzman, J. C.; Elachi, C.

1980-01-01

379

Landform identification: Lunar radar images  

NASA Technical Reports Server (NTRS)

Three sets of polarized radar-echo images of the Moon were examined to establish the relation between radar resolution and landform-identification resolution. After comparison with lunar maps and photographs, real and apparent landforms on the radar images were grouped into one of seven classes. Results show strong relations between radar resolution and diameter or relief of landforms that are clearly identified and those that would probably be correctly identified (class 1 and class 2). Landforms are not detected (class 5) at all diameters and reliefs, but the percentage of undetected landforms decreases with increasing mean diameter and mean relief. Landforms are simply detected (class 4) at most mean diameters and reliefs. Ambiguous arrays (class 6) portrayed by the radar constitute up to about 16, 22, and 15% of the landforms at various diameters and relief values for the 3.8 cm, 70 cm high resolution, and 70 cm low resolution images, respectively. Only a few percent of the landforms portrayed by the radar images at various diameters and relief values are fictitious (class 7).

Moore, Henry J.; Thompson, T. W.

1987-01-01

380

Observing hourly changes in a glacier's surface with Terrestrial Radar Interferometry  

NASA Astrophysics Data System (ADS)

Capturing rapid changes in the surface of a glacier requires frequent observations. Terrestrial Radar Interferometry (TRI) is a new technique that relies on a portable, ground-based radar to image the terminal zones of glaciers up to 10 km from the calving front. TRI offers denser spatial sampling than GPS and higher temporal sampling than satellite SAR, making it an excellent tool to monitor fast-moving glaciers. This study focuses on developing methods to generate robust topographic and deformation maps with TRI. Breidamerkurjokull is a fast-moving glacier in southeastern Iceland with summer velocities as high as 4 m/d at the calving front. The glacier terminates at, and continuously calves icebergs into, a tidally-influenced lagoon. To better understand its dynamics, we image the glacier with the GAMMA Portable Radar Interferometer (GPRI). The GPRI is a Ku-band real-aperture radar with one transmitting and two receiving antennas. The configuration of the receiving antennas allows estimates of glacier topography with each subsequent image acquisition along with a deformation map, since the baseline between the antennas is known and fixed. We will present results that show the temporal evolution of the glacier's surface over a period of approximately one week, including volumetric ice change estimates for the imaged area.

Voytenko, D.; Dixon, T. H.; Osmanoglu, B.; Werner, C. L.; Howat, I. M.

2012-12-01

381

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

NASA Astrophysics Data System (ADS)

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.

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

382

Coherent Thermoelectric Effects in Mesoscopic Andreev Interferometers  

E-print Network

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

Ph. Jacquod; R. S. Whitney

2009-10-15

383

An 'X-banded' Tidbinbilla interferometer  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

384

Over-under double-pass interferometer  

NASA Technical Reports Server (NTRS)

An over-under double-pass interferometer in which the beamsplitter area and thickness can be reduced to conform only with optical flatness considerations is 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, beam-splitting area of the beamsplitter and passed to a detector. This makes the beamsplitter insensitive to minimum-thickness requirements and selection of material.

Schindler, Rudolf A. (Inventor)

1980-01-01

385

Over-under double-pass interferometer  

NASA Technical Reports Server (NTRS)

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.

Schindler, R. A. (inventor)

1977-01-01

386

VINCI: the VLT Interferometer commissioning instrument  

NASA Astrophysics Data System (ADS)

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.

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

2000-07-01

387

Ultra deep nulling interferometry using fractal interferometers  

NASA Astrophysics Data System (ADS)

The difficult goal of directly detecting a planet around a star requires the cancellation of, as far as possible, the stellar light and nulling interferometry is one way to do so: the star is put on a central dark fringe while the planet is supposed to be on a bright fringe. One problem is, however, leaks due to the finite angular dimension of the stellar disk, resolved by the interferometer. The solution is to increase the exponent of the term ? which describes the cancellation efficiency with respect to the angular distance to the axis of the central dark fringe. Efficient configurations have been found, using basically guess and check methods until recently. I present here one method to define configurations of telescopes that achieve any given power of ?. The principle is based on a peculiar property of a partition into two sets of the first 2 integers; the partition is built using the Prouhet Thué Morse sequence which presents some fractal properties. A phase shift (0 or ?) between 2 telescopes is applied according to this partition. I first examine 1-D pattern of identical telescopes, then extend the method to 2-D configurations of identical telescopes, to 1-D arrays and 2-D arrays of non-identical telescopes and finally to arrays where the phase shift between n groups of telescopes is 2k?/n. I examine then how a non-perfect fractal interferometer behaves and show that its robustness with respect to nulling stability is an important advantage. To cite this article: D. Rouan, C. R. Physique 8 (2007).

Rouan, Daniel

2007-04-01

388

Effect of scattering on radar system performance  

NASA Astrophysics Data System (ADS)

The effect of both forward and backward scattering effect on the performance of radar systems was investigated. It is shown that forward scatter causes considerable error in the target elevation in tracking radars. Thus, low angle tracking radars are greatly affected by specular reflection whereas airborne tracking radars are affected by forward scatter. The backscattered signal (clutter) reduces the maximum range of the pulse radar to a great extent. Finally, the radar range decreases rapidly with increasing grazing angles. This implies that the probability of detection of a target decreases as the grazing angle increases.

Vishvakarma, Babau Ram; Taha, Bazil; Al-Hafid, H. T.

389

Australian Weather Watch Radar Home Page  

NSDL National Science Digital Library

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

390

Urbana radar systems: Possibilities and limitations  

NASA Astrophysics Data System (ADS)

The Aeronomy Laboratory Field Station of the University of Illinois at Urbana contains three different radar systems capable of probing various regions of the atmosphere below about 100 km. These are an mesosphere-stratosphere-troposphere (MST) radar, a VHF meteor radar and an MF partial-reflection radar. All three radars can measure winds and waves in the ionospheric D region. The MST radar is, in addition, capable of probing the lower stratosphere and upper troposphere. A sodium (Na) LIDAR is also located at the Field Station and provides an additional way of studing winds and waves in the mesosphere by observing temporal variations in the sodium density profile.

Royrvik, O.

1984-12-01

391

All-digital radar architecture  

NASA Astrophysics Data System (ADS)

All digital radar architecture requires exclude mechanical scan system. The phase antenna array is necessarily large because the array elements must be co-located with very precise dimensions and will need high accuracy phase processing system for aggregate and distribute T/R modules data to/from antenna elements. Even phase array cannot provide wide field of view. New nature inspired all digital radar architecture proposed. The fly's eye consists of multiple angularly spaced sensors giving the fly simultaneously thee wide-area visual coverage it needs to detect and avoid the threats around him. Fly eye radar antenna array consist multiple directional antennas loose distributed along perimeter of ground vehicle or aircraft and coupled with receiving/transmitting front end modules connected by digital interface to central processor. Non-steering antenna array allows creating all-digital radar with extreme flexible architecture. Fly eye radar architecture provides wide possibility of digital modulation and different waveform generation. Simultaneous correlation and integration of thousands signals per second from each point of surveillance area allows not only detecting of low level signals ((low profile targets), but help to recognize and classify signals (targets) by using diversity signals, polarization modulation and intelligent processing. Proposed all digital radar architecture with distributed directional antenna array can provide a 3D space vector to the jammer by verification direction of arrival for signals sources and as result jam/spoof protection not only for radar systems, but for communication systems and any navigation constellation system, for both encrypted or unencrypted signals, for not limited number or close positioned jammers.

Molchanov, Pavlo A.

2014-10-01

392

Single-pass rub testing of abradable seal materials  

NASA Technical Reports Server (NTRS)

A pendulum-type test device has been built for use in studying rubs between a turbine or compressor blade tip or labyrinth seal knife edge and specimens of abradable gas path seal materials. The device allows measurement of the rub energy dissipated in a single wear event, along with friction and normal forces and wear. Subsequent rubs over the same surface can also be monitored, with microscopic observation of the rub surface being possible after any of the passes. The device was used in tests of several potential abradable materials, ranging from porous to fully dense. It was shown that the rub energy dissipated in initial and subsequent passes is a fundamental parameter in the evaluation of material abradability. Rub energy was found to be influenced by such factors as: density and tensile (or yield) strength of the abradable material, prior densification or work hardening of the rub surface, and the sharpness of the leading edge of the blade tip.

Kennedy, F. E.; Hine, N. P.

1981-01-01

393

Single-pass memory system evaluation for multiprogramming workloads  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

394

Orbital Single-Pass Interferometry for Vessel Detection and Classification  

Microsoft Academic Search

This manuscript tackles the possible usage of Polarimetric SAR interferometry in vessel classification. It presents a simple technique that combines the retrieved height information with a Pauli analysis of polarimetric data to build a tri-dimensional map of scattering centers. By comparing this output with a vessel pattern database generated from previous scattering studies, a decision on vessel identification can then

Gerard Margarit; Jordi J. Mallorqui; J. M. Rius; Jesus Sanz-Marcos; Xavier Fabregas

2006-01-01

395

A Study of Single Pass Ion Effects at the ALS  

SciTech Connect

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.

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

2011-09-13

396

Hanford single-pass reactor fuel storage basin demolition.  

PubMed

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

Armstrong, Jason A

2003-02-01

397

Hanford Single-Pass Reactor Fuel Storage Basin Demolition.  

PubMed

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

Armstrong, Jason A.

2003-02-01

398

Large-aperture interferometer using local reference beam  

NASA Technical Reports Server (NTRS)

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.

Howes, W. L.

1982-01-01

399

Developing a new hyperspectral imaging interferometer for earth observation  

NASA Astrophysics Data System (ADS)

The Aerospace Leap-frog Imaging Stationary interferometer for Earth Observation (ALISEO) is a hyperspectral imaging interferometer for Earth remote sensing. The instrument belongs to the class of Sagnac stationary interferometers and acquires the image of the target superimposed to the pattern of autocorrelation functions of the electromagnetic field coming from each pixel. The ALISEO sensor together with the data processing algorithms that retrieve the at-sensor spectral radiance are discussed. A model describing the instrument OPD and interferogram center is also discussed, improving the procedures for phase retrieval and spectral estimation. Images acquired by ALISEO are shown, and examples of retrieved reflectance spectra are presented.

Barducci, Alessandro; Castagnoli, Francesco; Castellini, Guido; Guzzi, Donatella; Lastri, Cinzia; Marcoionni, Paolo; Nardino, Vanni; Pippi, Ivan

2012-11-01

400

Topological phase shift in a cold-atom interferometer  

NASA Astrophysics Data System (ADS)

Matter-wave interferences in a four-pulse version of a Ramsey-Bordé atom interferometer have been utilized to study phase shifts. A topological phase shift analogous to the scalar Aharonov-Bohm effect proposed for charged-particle interferences in the presence of a pulsed electrostatic potential has been investigated. The time-dependent potential has been generated by the interaction of a laser field with an induced atomic dipole without spatial variation along the interferometer arms. The atom interferometer has been run with laser-cooled magnesium atoms stored in a magneto-optical trap.

Müller, J. H.; Bettermann, D.; Rieger, V.; Sengstock, K.; Sterr, U.; Ertmer, W.

1995-02-01

401

Fourier-transform and global contrast interferometer alignment methods  

DOEpatents

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.

Goldberg, Kenneth A. (Berkeley, CA)

2001-01-01

402

Instantaneous Radar Polarimetry with Multiple Dually-polarized Antennas  

Microsoft Academic Search

Fully polarimetric radar systems are capable of simultaneously transmitting and receiving in two orthogonal polarizations. Instantaneous radar polarimetry exploits both polarization modes of a dually-polarized radar transmitter and receiver on a pulse by pulse basis, and can improve the radar detection performance and suppress range sidelobes . In this paper, we extend the use of instantaneous radar polarimetry for radar

A. R. Calderbank; S. D. Howard; W. Moran; A. Pezeshki; M. Zoltowski

2006-01-01

403

Spatially Waveform Diverse Radar: Perspectives for High Frequency OTHR  

Microsoft Academic Search

The application of multi-input multi-output (MIMO) radar concepts to HF over-the-horizon radar is considered to improve radar timeline management flexibility and to permit adaptivity on transmit. MIMO radar concepts in the literature are inconsistent and in this paper the taxonomy of MIMO radar is clarified and distinctions between different MIMO radar types drawn. The term \\

Gordon J. Frazer; Yuri I. Abramovich; B. A. Johnson

2007-01-01

404

A comparison between matter wave and light wave interferometers for the detection of gravitational waves  

E-print Network

We calculate and compare the response of light wave interferometers and matter wave interferometers to gravitational waves. We find that metric matter wave interferometers will not challenge kilometric light wave interferometers such as Virgo or LIGO, but could be a good candidate for the detection of very low frequency gravitational waves.

Pacôme Delva; Marie-Christine Angonin; Philippe Tourrenc

2006-09-20

405

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

E-print Network

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

Paris-Sud XI, Université de

406

VALIDATION OF A RADAR DOPPLER SPECTRA SIMULATOR USING MEASUREMENTS FROM THE ARM CLOUD RADARS  

E-print Network

VALIDATION OF A RADAR DOPPLER SPECTRA SIMULATOR USING MEASUREMENTS FROM THE ARM CLOUD RADARS to compare models with observations contains advantages and challenges. Radar Doppler spectra simulators model output with the Doppler spectra recorded from the vertically pointing cloud radars at the ARM

407

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

E-print Network

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

Willsky, Alan S.

408

MST radar data-base management  

NASA Technical Reports Server (NTRS)

Data management for Mesospheric-Stratospheric-Tropospheric, (MST) radars is addressed. An incoherent-scatter radar data base is discussed in terms of purpose, centralization, scope, and nature of the data base management system.

Wickwar, V. B.

1983-01-01

409

Levee Monitoring with Radar Remote Sensing  

NASA Technical Reports Server (NTRS)

Topics in this presentation are: 1. Overview of radar remote sensing 2. Surface change detection with Differential Interferometric Radar Processing 3. Study of the Sacramento - San Joaquin levees 4. Mississippi River Levees during the Spring 2011 floods.

Jones, Cathleen E.

2012-01-01

410

Obstacle penetrating dynamic radar imaging system  

DOEpatents

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

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

2006-12-12

411

MIMO Radar Waveform Constraints for GMTI  

E-print Network

Ground moving-target indication (GMTI) provides both an opportunity and challenge for coherent multiple-input multiple-output (MIMO) radar. MIMO techniques can improve a radar's angle estimation and the minimum detectable ...

Forsythe, Keith W.

412

Signal processing for airborne bistatic radar   

E-print Network

The major problem encountered by an airborne bistatic radar is the suppression of bistatic clutter. Unlike clutter echoes for a sidelooking airborne monostatic radar, bistatic clutter echoes are range dependent. Using ...

Ong, Kian P

413

Meteorological radar facility. Part 1: System design  

NASA Technical Reports Server (NTRS)

A compilation of information regarding systems design of space shuttles used in meteorological radar probes is presented. Necessary radar equipment is delineated, while space system elements, calibration techniques, antenna systems and other subsystems are reviewed.

Brassaw, L. L., Jr.; Hamren, S. D.; Mullins, W. H.; Schweitzer, B. P.

1976-01-01

414

Eliminating Clutter in Synthetic-Aperture Radar  

NASA Technical Reports Server (NTRS)

Diffusion technique reduces clutter noise in coherent SAR (synthetic-aperature radar) image signal without degrading its resolution. Technique makes radar-mapped terrain features more obvious.It also has potential application in holographic microscopy.

Jain, A.

1979-01-01

415

Progress in existing and planned MST radars  

NASA Astrophysics Data System (ADS)

Radar systems are described which use two different wind measuring techniques: the partial-reflection drift technique and the mesosphere-stratosphere-troposphere (MST) or Doppler beam-swing radar technique. The advantages and disadvantages of each technique are discussed.

Vanzandt, T. E.

1986-06-01

416

Progress in existing and planned MST radars  

NASA Technical Reports Server (NTRS)

Radar systems are described which use two different wind measuring techniques: the partial-reflection drift technique and the mesosphere-stratosphere-troposphere (MST) or Doppler beam-swing radar technique. The advantages and disadvantages of each technique are discussed.

Vanzandt, T. E.

1986-01-01

417

Extended target recognition in cognitive radar networks.  

PubMed

We address the problem of adaptive waveform design for extended target recognition in cognitive radar networks. A closed-loop active target recognition radar system is extended to the case of a centralized cognitive radar network, in which a generalized likelihood ratio (GLR) based sequential hypothesis testing (SHT) framework is employed. Using Doppler velocities measured by multiple radars, the target aspect angle for each radar is calculated. The joint probability of each target hypothesis is then updated using observations from different radar line of sights (LOS). Based on these probabilities, a minimum correlation algorithm is proposed to adaptively design the transmit waveform for each radar in an amplitude fluctuation situation. Simulation results demonstrate performance improvements due to the cognitive radar network and adaptive waveform design. Our minimum correlation algorithm outperforms the eigen-waveform solution and other non-cognitive waveform design approaches. PMID:22163464

Wei, Yimin; Meng, Huadong; Liu, Yimin; Wang, Xiqin

2010-01-01

418

German Radar Observation Shuttle Experiment (ROSE)  

NASA Technical Reports Server (NTRS)

The success of radar sensors in several different application areas of interest depends on the knowledge of the backscatter of radar waves from the targets of interest, the variance of these interaction mechanisms with respect to changing measurement parameters, and the determination of the influence of he measuring systems on the results. The incidence-angle dependency of the radar cross section of different natural targets is derived. Problems involved by the combination of data gained with different sensors, e.g., MSS-, TM-, SPOTand SAR-images are analyzed. Radar cross-section values gained with ground-based radar spectrometers and spaceborne radar imaging, and non-imaging scatterometers and spaceborne radar images from the same areal target are correlated. The penetration of L-band radar waves into vegetated and nonvegetated surfaces is analyzed.

Sleber, A. J.; Hartl, P.; Haydn, R.; Hildebrandt, G.; Konecny, G.; Muehlfeld, R.

1984-01-01

419

Spaceborne radar remote sensing: Applications and techniques  

Microsoft Academic Search

The operation and applications of spaceborne radars for terrestrial and planetary remote sensing are described in an introduction for advanced students and practicing scientists. Chapters are devoted to imaging radars, wave-surface interactions and geoscientific applications, real- and synthetic-aperture radars, end-to-end system design, SAR data processing, altimeters, and scatterometers. Extensive diagrams, drawings, graphs, photographs, and sample radar images are provided.

Charles Elachi

1988-01-01

420

Radar Images of the Earth: Interferometry  

NSDL National Science Digital Library

This site features links to nineteen NASA radar images using interferometry to enhance details or measure changes in elevation. The image pages contain brief descriptions of the respective processes and settings. They were created with the Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) as part of NASA's Mission to Planet Earth. The radar illuminates Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions.

421

Radar Images of the Earth: Volcanoes  

NSDL National Science Digital Library

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

422

Radar Images of the Earth: Cities  

NSDL National Science Digital Library

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

423

Space Radar Images of the Earth: Archaeology  

NSDL National Science Digital Library

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

424

Radar Images of the Earth: Oceans  

NSDL National Science Digital Library

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

425

Orthogonal polarization Mirau interferometer using reflective-type waveplate.  

PubMed

This work proposes an orthogonal polarization Mirau interferometry using a reflective-type waveplate to generate different polarization orientations for broadband white light interferometry. The reflective-type half-waveplate is employed as the reference arm of the Mirau interferometer to convert polarization and it generates a reference light with an orientation orthogonal to the object light. An advantage of the proposed interferometer is its ability to control the ratio of light intensity between the object and reference arms to maximize the interferometric fringe contrast. Better, more accurate calibration of standard step height has been achieved by the developed interferometer, which also can measure solder bumps that traditional Mirau interferometers usually cannot measure. PMID:23939094

Tapilouw, Abraham Mario; Chen, Liang-Chia; Jen, Yi-Jun; Lin, Shyh-Tsong; Yeh, Sheng-Lih

2013-07-15

426

A polarization sensitive interferometer for Faraday rotation detection.  

E-print Network

??Time-resolved Faraday rotation (TRFR) is a pulsed laser pump/probe optical measurement used to characterize electron spin dynamics in semiconductor materials. A Mach-Zehnder type interferometer with… (more)

LaForge, Joshua Michael

2007-01-01

427

On the design of lithographic interferometers and their application  

E-print Network

Interference lithography is presented as an ideal technique for fabricating large-area periodic structures with sub-100nm dimensions. A variety of interferometer designs are discussed and implemented, each of which emphasizes ...

Walsh, Michael E. (Michael Edward), 1975-

2004-01-01

428

Feasibility of a Small Scale Intensity Correlation Interferometer  

E-print Network

Demand for high-resolution imaging capabilities for both space-based and ground-based imaging systems has created significant interest in improving the design of multi-aperture interferometry imaging systems. Interferometers are a desirable...

Kelderman, Gregory Peter

2013-04-29

429

Two-interferometers fiber optic sensor for disturbance localization  

NASA Astrophysics Data System (ADS)

Initial researches of Two-interferometers Fibre Optic Sensor for Disturbance Localization will be presented. The sensor is typically susceptible to environmentally induced mechanical perturbation at low frequencies. The presented sensor consists of two interferometers: Sagnac and Michelson. The Sagnac transfer function is proportional to the product of two factors: firstly the rate of change, d?/dt, of the optical signal, induced at a point by external disturbance, and secondly the distance between the disturbance point and the Sagnac coil centre. The second interferometer transfer function gives an output proportional to ?. So, if we determine a pulsation ? of the mechanical disturbance from both interferometers output signals, we will be able to localize point where the mechanical disturbance takes place along the fibre by means of simple division of these transfer function. A laboratory arrangement of the sensor and the results of numerical signal processing are also shown.

Zyczkowski, Marek; Ciurapinski, Wieslaw; Kondrat, Marcin

2005-09-01

430

Interferometer combines laser light source and digital counting system  

NASA Technical Reports Server (NTRS)

Measurement of small linear displacements in digital readouts with extreme accuracy and sensitivity is achieved by an interferometer. The instrument combines a digital electro-optical fringe-counting system and a laser light source.

1965-01-01

431

SMAP RADAR Processing and Calibration  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

432

Scanning ARM Cloud Radar Handbook  

SciTech Connect

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

Widener, K; Bharadwaj, N; Johnson, K

2012-06-18

433

GMTI radar minimum detectable velocity.  

SciTech Connect

Minimum detectable velocity (MDV) is a fundamental consideration for the design, implementation, and exploitation of ground moving-target indication (GMTI) radar imaging modes. All single-phase-center air-to-ground radars are characterized by an MDV, or a minimum radial velocity below which motion of a discrete nonstationary target is indistinguishable from the relative motion between the platform and the ground. Targets with radial velocities less than MDV are typically overwhelmed by endoclutter ground returns, and are thus not generally detectable. Targets with radial velocities greater than MDV typically produce distinct returns falling outside of the endoclutter ground returns, and are thus generally discernible using straightforward detection algorithms. This document provides a straightforward derivation of MDV for an air-to-ground single-phase-center GMTI radar operating in an arbitrary geometry.

Richards, John Alfred

2011-04-01

434

Airborne Differential Doppler Weather Radar  

NASA Technical Reports Server (NTRS)

The Precipitation Radar aboard the Tropical Rain Measuring Mission (TRMM) Satellite has shown the potential for spaceborne sensing of snow and rain by means of an incoherent pulsed radar operating at 13.8 GHz. The primary advantage of radar relative to passive instruments arises from the fact that the radar can image the 3-dimensional structure of storms. As a consequence, the radar data can be used to determine the vertical rain structure, rain type (convective/stratiform) effective storm height, and location of the melting layer. The radar, moreover, can be used to detect snow and improve the estimation of rain rate over land. To move toward spaceborne weather radars that can be deployed routinely as part of an instrument set consisting of passive and active sensors will require the development of less expensive, lighter-weight radars that consume less power. At the same time, the addition of a second frequency and an upgrade to Doppler capability are features that are needed to retrieve information on the characteristics of the drop size distribution, vertical air motion and storm dynamics. One approach to the problem is to use a single broad-band transmitter-receiver and antenna where two narrow-band frequencies are spaced apart by 5% to 10% of the center frequency. Use of Ka-band frequencies (26.5 GHz - 40 GHz) affords two advantages: adequate spatial resolution can be attained with a relatively small antenna and the differential reflectivity and mean Doppler signals are directly related to the median mass diameter of the snow and raindrop size distributions. The differential mean Doppler signal has the additional property that this quantity depends only on that part of the radial speed of the hydrometeors that is drop-size dependent. In principle, the mean and differential mean Doppler from a near-nadir viewing radar can be used to retrieve vertical air motion as well as the total mean radial velocity. In the paper, we present theoretical calculations for the differential reflectivity and Doppler as functions of the center frequency, frequency difference, and median mass diameter. For a fixed pair of frequencies, the detectability of the differential signals can be expressed as the number of independent samples required to detect rain or snow with a particular median mass diameter. Because sampling numbers on the order of 1000 are needed to detect the differential signal over a range of size distributions, the instrument must be confined to a near-nadir, narrow swath. Radar measurements from a zenith directed radar operated at 9.1 GHz and 10 GHz are used to investigate the qualitative characteristics of the differential signals. Disdrometer and rain gauge data taken at the surface, just below the radar, are used to test whether the differential signals can be used to estimate characteristics of the raindrop size distribution.

Meneghini, R.; Bidwell, S.; Liao, L.; Rincon, R.; Heymsfield, G.; Hildebrand, Peter H. (Technical Monitor)

2001-01-01

435

Agricultural and hydrological applications of radar  

Microsoft Academic Search

Program objectives, covering a wide range of disciplines and activities in radar remote sensing, include radar systems development and analysis, data processing and display, and data interpretation in geology, geography and oceanography. Research was focused on the evaluation of radar remote sensing applications in hydrology and agriculture based on data acquired with the Microwave Active Spectrometer (MAS) system. The title,

F. T. Ulaby

1976-01-01

436

Radar Technology Applied to Air Traffic Control  

Microsoft Academic Search

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

WILLIAM W. SHRADER

1973-01-01

437

46 CFR 11.480 - Radar observer.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Radar observer. 11.480 Section 11.480...Requirements for Deck Officers § 11.480 Radar observer. (a) This section contains...that an applicant must meet to qualify as a radar observer. (Part 15 of this chapter...

2013-10-01

438

46 CFR 169.726 - Radar reflector.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Radar reflector. 169.726 Section 169...Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design...

2012-10-01

439

46 CFR 130.310 - Radar.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

440

46 CFR 15.815 - Radar observers.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Radar observers. 15.815 Section 15.815...REQUIREMENTS Computations § 15.815 Radar observers. (a) Each person in...vessels of 300 gross tons or over which are radar equipped, shall hold an endorsement...

2012-10-01

441

EISCAT Radar School, Kiruna, 2005 Outrigger in  

E-print Network

EISCAT Radar School, Kiruna, 2005 LOFAR Outrigger in Scandinavia Physics in Space Programme LOFAR Centre, Växjö University #12;Bo Thidé EISCAT Radar School, Kiruna,, 20052 LOFAR Low Frequency Array (10 radio system for space radio #12;Bo Thidé EISCAT Radar School, Kiruna,, 20053 Hydrogen radiates at 1420

442

46 CFR 184.404 - Radars.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

443

46 CFR 108.717 - Radar.  

...2014-10-01 2014-10-01 false Radar. 108.717 Section 108.717 Shipping...Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1...coastwise service must have— (a) A marine radar system for surface navigation; and...

2014-10-01

444

46 CFR 130.310 - Radar.  

...2014-10-01 2014-10-01 false Radar. 130.310 Section 130.310 Shipping... Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the...

2014-10-01

445

46 CFR 108.717 - Radar.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Radar. 108.717 Section 108.717 Shipping...Miscellaneous Equipment § 108.717 Radar. Each self-propelled unit of 1...coastwise service must have— (a) A marine radar system for surface navigation; and...

2013-10-01

446

46 CFR 15.815 - Radar observers.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

447

46 CFR 108.717 - Radar.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

448

46 CFR 108.717 - Radar.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

449

46 CFR 130.310 - Radar.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Radar. 130.310 Section 130.310 Shipping... Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the...

2012-10-01

450

46 CFR 121.404 - Radars.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

451

46 CFR 121.404 - Radars.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

452

46 CFR 169.726 - Radar reflector.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

453

46 CFR 169.726 - Radar reflector.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Radar reflector. 169.726 Section 169...Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design...

2013-10-01

454

46 CFR 167.40-40 - Radar.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Radar. 167.40-40 Section 167.40-40...Equipment Requirements § 167.40-40 Radar. All mechanically propelled vessels...coastwise service must be fitted with a marine radar system for surface navigation....

2012-10-01

455

46 CFR 15.815 - Radar observers.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Radar observers. 15.815 Section 15.815...REQUIREMENTS Computations § 15.815 Radar observers. (a) Each person in...vessels of 300 gross tons or over which are radar equipped, shall hold an endorsement...

2013-10-01

456

46 CFR 169.726 - Radar reflector.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

457

46 CFR 15.815 - Radar observers.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

458

46 CFR 121.404 - Radars.  

...2014-10-01 2014-10-01 false Radars. 121.404 Section 121.404 Shipping... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph...Commission (FCC) type accepted general marine radar system for surface navigation with...

2014-10-01

459

46 CFR 121.404 - Radars.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Radars. 121.404 Section 121.404 Shipping... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph...Commission (FCC) type accepted general marine radar system for surface navigation with...

2013-10-01

460

APPLICATION OF SENSOR SCHEDULING CONCEPTS TO RADAR  

E-print Network

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

Nehorai, Arye

461

46 CFR 11.480 - Radar observer.  

...2014-10-01 2014-10-01 false Radar observer. 11.480 Section 11.480...Deck Officer Endorsements § 11.480 Radar observer. (a) This section contains...that an applicant must meet to qualify as a radar observer. (b) If an applicant...

2014-10-01

462

46 CFR 130.310 - Radar.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

463

46 CFR 11.480 - Radar observer.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Radar observer. 11.480 Section 11.480...Requirements for Deck Officers § 11.480 Radar observer. (a) This section contains...that an applicant must meet to qualify as a radar observer. (Part 15 of this chapter...

2012-10-01

464

46 CFR 15.815 - Radar observers.  

...2014-10-01 2014-10-01 false Radar observers. 15.815 Section 15.815...REQUIREMENTS Computations § 15.815 Radar observers. (a) Each person in...inspected vessels of 300 GRT or over which are radar equipped, must hold an endorsement...

2014-10-01

465

46 CFR 167.40-40 - Radar.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

466

46 CFR 167.40-40 - Radar.  

...2014-10-01 2014-10-01 false Radar. 167.40-40 Section 167.40-40...Equipment Requirements § 167.40-40 Radar. All mechanically propelled vessels...coastwise service must be fitted with a marine radar system for surface navigation....

2014-10-01

467

46 CFR 167.40-40 - Radar.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

468

46 CFR 184.404 - Radars.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Radars. 184.404 Section 184.404 Shipping... Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with...Commission (FCC) type accepted general marine radar system for surface navigation with...

2013-10-01

469

46 CFR 184.404 - Radars.  

...2014-10-01 2014-10-01 false Radars. 184.404 Section 184.404 Shipping... Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with...Commission (FCC) type accepted general marine radar system for surface navigation with...

2014-10-01

470

46 CFR 11.480 - Radar observer.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

471

46 CFR 130.310 - Radar.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Radar. 130.310 Section 130.310 Shipping... Navigational Equipment § 130.310 Radar. Each vessel of 100 or more gross tons must be fitted with a general marine radar in the...

2013-10-01

472

46 CFR 184.404 - Radars.  

Code of Federal Regulations, 2010 CFR

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

2010-10-01

473

46 CFR 121.404 - Radars.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Radars. 121.404 Section 121.404 Shipping... Navigation Equipment § 121.404 Radars. (a) Except as allowed by paragraph...Commission (FCC) type accepted general marine radar system for surface navigation with...

2012-10-01

474

WAVE-DRIVEN SURFACE FROM HF RADAR  

E-print Network

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

Miami, University of

475

Synthetic aperture radar calibration using reference reflectors  

Microsoft Academic Search

A simple expression for the terrain backscatter coefficient is derived in terms of the integrated power of an adjacent known radar reflector in a synthetic aperture radar (SAR) image. It is shown that this technique for SAR image calibration is independent of the radar system focus or partial coherence and thereby possesses an important advantage over the usual technique, which

A. L. Gray; P. W. Vachon; C. E. Livingstone; T. I. Lukowski

1990-01-01

476

46 CFR 11.480 - Radar observer.  

Code of Federal Regulations, 2011 CFR

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

2011-10-01

477

46 CFR 167.40-40 - Radar.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Radar. 167.40-40 Section 167.40-40...Equipment Requirements § 167.40-40 Radar. All mechanically propelled vessels...coastwise service must be fitted with a marine radar system for surface navigation....

2013-10-01

478

46 CFR 184.404 - Radars.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Radars. 184.404 Section 184.404 Shipping... Navigation Equipment § 184.404 Radars. (a) A vessel must be fitted with...Commission (FCC) type accepted general marine radar system for surface navigation with...

2012-10-01

479

46 CFR 169.726 - Radar reflector.  

...2014-10-01 2014-10-01 false Radar reflector. 169.726 Section 169...Systems, and Equipment § 169.726 Radar reflector. Each nonmetallic vessel less than 90 feet in length must exhibit a radar reflector of suitable size and design...

2014-10-01

480

Efficient Ways to Learn Weather Radar Polarimetry  

ERIC Educational Resources Information Center

The U.S. weather radar network is currently being upgraded with dual-polarization capability. Weather radar polarimetry is an interdisciplinary area of engineering and meteorology. This paper presents efficient ways to learn weather radar polarimetry through several basic and practical topics. These topics include: 1) hydrometeor scattering model…

Cao, Qing; Yeary, M. B.; Zhang, Guifu

2012-01-01

481

Course Syllabus Course name: Radar Meteorology  

E-print Network

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

482

Noise modulated multistatic surveillance radar concept  

Microsoft Academic Search

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

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

2006-01-01

483

Simple Sea Clutter Canceller for Noise Radar  

Microsoft Academic Search

In the last decade the noise radar technology is intensively investigated. The low transmitting power and nonspecific waveform makes that the noise radar has very god LPI properties. The simultaneous emission and reception of signals in such kind of radars make them sensitive to near-far problem. Strong echoes, originated from ground clutter can completely mask the weak target return. In

Krzysztof Kulpa

2006-01-01

484

CWLFM Radar for Ship Detection and Identification  

Microsoft Academic Search

Continuous wave lineal frequency modulated (CWLFM) radar presents some interesting advantages for coast surveillance and control as well as low probability of interception (LPI). This paper presents real results obtained with a radar prototype and processed with ISAR techniques. Also, results of an automatic ship identification system applied to simulated ISAR images are exposed. Moreover, radar behavior with unfavorable meteorological

C. C. Duarte; B. P. Dorta Naranjo; A. A. Lopez; A. B. del Campo

2007-01-01

485

The design of broadband radar absorbing surfaces  

Microsoft Academic Search

There has been a growing and widespread interest in radar absorbing material technology. As the name implies, radar absorbing materials or RAM's are coatings whose electric and magnetic properties have been selected to allow the absorption of microwave energy at discrete or broadband frequencies. In military applications low radar cross section (RCS) of a vehicle may be required in order

Go H. Suk

1990-01-01

486

Nonsinusoidal radar signal design for stealth targets  

Microsoft Academic Search

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

Nasser J. Mohamed

1995-01-01

487

Tracking radar studies of bird migration  

NASA Technical Reports Server (NTRS)

The application of tracking radar for determining the flight paths of migratory birds is discussed. The effects produced by various meteorological parameters are described. Samples of radar scope presentations obtained during tracking studies are presented. The characteristics of the radars and their limitations are examined.

Williams, T. C.; Williams, J. M.; Teal, J. M.; Kanwisher, J. W.

1972-01-01

488

Performance analysis of radar antenna systems  

Microsoft Academic Search

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

J. J. Kim; O. B. Kesler

1999-01-01

489

Installed performance analysis of radar antenna systems  

Microsoft Academic Search

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

Jacob J. Kim; Oren B. Kesler

1998-01-01

490

Jet stream related observations by MST radars  

NASA Technical Reports Server (NTRS)

An overview of the jet stream and its observation by MST radar is presented. The climatology and synoptic and mesoscale structure of jet streams is briefly reviewed. MST radar observations of jet stream winds, and associated waves and turbulence are then considered. The possibility of using a network of ST radars to track jet stream winds in near real time is explored.

Gage, K. S.

1983-01-01

491

Radar target classification of commercial aircraft  

Microsoft Academic Search

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

ANTHONY ZYWECK; ROBERT E. BOGNER

1996-01-01

492

Autonomous deployment of the UAVSAR radar instrument  

Microsoft Academic Search

The UAVSAR program was formed to provide repeat pass radar interferometry on an uninhabited aircraft platform. The UAVSAR imaging radar system is housed in an external unpressurized pod that may be attached to an Uninhabited Aerial Vehicle (UAV), although initial flight tests were performed aboard a Gulfstream-III aircraft with flight test personnel on-board. Since the radar science missions are to

K. Vines; R. Chao

2010-01-01

493

UAV Collision Avoidance Radar - Build and Test  

Microsoft Academic Search

This paper describes an experimental radar and data recording system designed to provide the 'sense and avoid' capability required by UAV's to fly in uncontrolled airspace. The radar incorporates the MIMO technique, forming multiple staring beams giving wide angular protection. Algorithms for detection in clutter, tracking, and miss-distance estimation for this radar have been developed, based on synthesised data only,

Benjamin J. Shannon; Ashoka Halappa; Ian D. Longstaff

494

Submillimeter laser interferometer for high density plasma diagnostic  

NASA Astrophysics Data System (ADS)

There are presented the results of investigation of the one-channel homodyne laser interferometer ?=119 µm made on the basis of the hollow dielectric beamguide and quasioptical functional devices. The interferometer is designed for determination of the plasma electron density of the TOKAMAK-7. The density response threshold is 0.7% from the expected plasma density and the phase difference measurement total error is 5°

Kamenev, Yu. E.; Kiselyev, V. K.; Kuleshov, E. M.; Knyaz'kov, B. N.; Kononenko, V. K.; Nesterov, P. K.; Yanovsky, M. S.

1995-06-01

495

Phase Tomography Using X-ray Talbot Interferometer  

Microsoft Academic Search

A biological tomography result obtained with an X-ray Talbot interferometer is reported. An X-ray Talbot interferometer was constructed using an amplitude grating fabricated by X-ray lithography at the LIGA beamline of NewSUBARU and gold electroplating. The pitch and pattern thickness of the grating were 8 mum and 30 mum, respectively. The effective area was 20 × 20 mm2, which was

A. Momose; W. Yashiro; Y. Takeda; M. Moritake; K. Uesugi; Y. Suzuki; T. Hattori

2007-01-01

496

Remote polarization control for fiber-optic interferometers.  

PubMed

A simple method has been developed for control and prevention of polarization fade on a single output lead from a remotely located fiber-optic interferometer. The method has been demonstrated using a fiber-optic Michelson interferometer. In contrast to a previously suggested method, only a single detector is required. The technique has application for passive, remotely located sensors. Extension to balanced homodyne detection schemes and coherent communications is discussed. PMID:19738844

Wanser, K H; Safar, N H

1987-03-01

497

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

SciTech Connect

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.

Khriplovich, I. B. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation); Lamoreaux, S. K.; Sushkov, A. O. [Department of Physics, Yale University, Post Office Box