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Sample records for acoustic interferometry sfai

  1. Applications of swept-frequency acoustic interferometry technique in chemical diagnostics

    SciTech Connect

    Sinha, D.N.; Springer, K.; Lizon, D.; Hasse, R.

    1996-09-01

    Swept-Frequency Acoustic Interferometry (SFAI) is a noninvasive fluid characterization technique currently being developed for chemical weapons treaty verification. The SFAI technique determines sound speed and sound attenuation in a fluid over a wide frequency range completely noninvasively from outside a container (e.g., pipe, tank, reactor vessel, etc.,). These acoustic parameters, along with their frequency-dependence, can be used to identify various chemicals. This technique can be adapted for a range of chemical diagnostic applications, particularly, in process control where monitoring of acoustic properties of chemicals may provide appropriate feedback information. Both experimental data and theoretical modeling are presented. Examples of several novel applications of the SFAI technique are discussed.

  2. Swept frequency acoustic interferometry technique for chemical weapons verification and monitoring

    SciTech Connect

    Sinha, D.N.; Anthony, B.W.; Lizon, D.C.

    1995-03-01

    Nondestructive evaluation (NDE) techniques are important for rapid on-site verification and monitoring of chemical munitions, such as artillery shells and bulk containers. Present NDE techniques provide only limited characterizations of such munitions. This paper describes the development of a novel noninvasive technique, swept-frequency acoustic interferometry (SFAI), that significantly enhances the capability of munitions characterizations. The SFAI technique allows very accurate and simultaneous determination of sound velocity and attenuation of chemical agents over a large frequency range inside artillery shells, in addition to determining agent density. The frequency-dependent sound velocity and attenuation can, in principle, provide molecular relaxation properties of the chemical agent. The same instrument also enables a direct fill-level measurement in bulk containers. Industrial and other applications of this general-purpose technique are also discussed.

  3. Applications of swept-frequency acoustic interferometer for nonintrusive detection and identification of chemical warfare compounds

    SciTech Connect

    Sinha, D.N.; Springer, K.; Han, W.; Lizon, D.; Kogan, S.

    1997-12-01

    Swept-Frequency Acoustic Interferometry (SFAI) is a nonintrusive liquid characterization technique developed specifically for detecting and identifying chemical warfare (CW) compounds inside sealed munitions. The SFAI technique can rapidly (less than 20 seconds) and accurately determine sound speed and sound attenuation of a liquid inside a container over a wide frequency range (1 kHz-15 MHz). From the frequency-dependent sound attenuation measurement, liquid density is determined. These three physical properties are used to uniquely identify the CW compounds. In addition, various chemical relaxation processes in liquids and particle size distribution in emulsions can also be determined from the frequency-dependent attenuation measurement. The SFAI instrument is battery-operated and highly portable (< 6 lb.). The instrument has many potential application in industry ranging from sensitive detection (ppm level) of contamination to process control. The theory of the technique will be described and examples of several chemical industry applications will be presented.

  4. Pulsed-Source Interferometry in Acoustic Imaging

    NASA Technical Reports Server (NTRS)

    Shcheglov, Kirill; Gutierrez, Roman; Tang, Tony K.

    2003-01-01

    A combination of pulsed-source interferometry and acoustic diffraction has been proposed for use in imaging subsurface microscopic defects and other features in such diverse objects as integrated-circuit chips, specimens of materials, and mechanical parts. A specimen to be inspected by this technique would be mounted with its bottom side in contact with an acoustic transducer driven by a continuous-wave acoustic signal at a suitable frequency, which could be as low as a megahertz or as high as a few hundred gigahertz. The top side of the specimen would be coupled to an object that would have a flat (when not vibrating) top surface and that would serve as the acoustical analog of an optical medium (in effect, an acoustical "optic").

  5. Imaging of acoustic fields using optical feedback interferometry.

    PubMed

    Bertling, Karl; Perchoux, Julien; Taimre, Thomas; Malkin, Robert; Robert, Daniel; Rakić, Aleksandar D; Bosch, Thierry

    2014-12-01

    This study introduces optical feedback interferometry as a simple and effective technique for the two-dimensional visualisation of acoustic fields. We present imaging results for several pressure distributions including those for progressive waves, standing waves, as well as the diffraction and interference patterns of the acoustic waves. The proposed solution has the distinct advantage of extreme optical simplicity and robustness thus opening the way to a low cost acoustic field imaging system based on mass produced laser diodes. PMID:25606963

  6. Applications of whole field interferometry in mechanics and acoustics

    NASA Astrophysics Data System (ADS)

    Molin, Nils-Erik

    1999-07-01

    A description is given of fringe formation in holographic interferometry, in electronic speckle pattern interferometry, in electro-optic or TV holography and for a newly developed system for pulsed TV-holography. A numerical example, which simulates the equations describing the different techniques, is included. A strain measuring system using defocused digital speckle photography is described. Experiments showing mode shapes of musical instruments, transient bending wave propagation in beams and plates as well as sound pressure fields in air are included.

  7. Noninvasive identification of fluids by swept-frequency acoustic interferometry

    DOEpatents

    Sinha, Dipen N.

    1998-01-01

    A method for rapid, noninvasive identification and monitoring of chemicals in sealed containers or containers where direct access to the chemical is not possible is described. Multiple ultrasonic acoustic properties (up to four) of a fluid are simultaneously determined. The present invention can be used for chemical identification and for determining changes in known chemicals from a variety of sources. It is not possible to identify all known chemicals based on the measured parameters, but known classes of chemicals in suspected containers, such as in chemical munitions, can be characterized. In addition, a large number of industrial chemicals can be identified.

  8. Interferometry

    NASA Technical Reports Server (NTRS)

    Ridgway, Stephen; Wilson, Robert W.; Begelman, Mitchell C.; Bender, Peter; Burke, Bernard F.; Cornwell, Tim; Drever, Ronald; Dyck, H. Melvin; Johnston, Kenneth J.; Kibblewhite, Edward

    1991-01-01

    The following recommended programs are reviewed: (1) infrared and optical interferometry (a ground-based and space programs); (2) compensation for the atmosphere with adaptive optics (a program for development and implementation of adaptive optics); and (3) gravitational waves (high frequency gravitational wave sources (LIGO), low frequency gravitational wave sources (LAGOS), a gravitational wave observatory program, laser gravitational wave observatory in space, and technology development during the 1990's). Prospects for international collaboration and related issues are also discussed.

  9. Imaging of transient surface acoustic waves by full-field photorefractive interferometry

    SciTech Connect

    Xiong, Jichuan; Xu, Xiaodong E-mail: christ.glorieux@fys.kuleuven.be; Glorieux, Christ E-mail: christ.glorieux@fys.kuleuven.be; Matsuda, Osamu; Cheng, Liping

    2015-05-15

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 μm. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz.

  10. Noninvasive Measurement of Acoustic Properties of Fluids Using Ultrasonic Interferometry Technique

    SciTech Connect

    Han, W.; Sinha, D.N.; Springer, K.N.; Lizon, D.C.

    1997-06-15

    A swept-frequency ultrasonic interferometry technique is used for noninvasively determining acoustic properties of fluids inside containers. Measurements over a frequency range 1-15 MHz on six liquid chemicals are presented. Measurements were made with the liquid inside standard rectangular optical glass cells and stainless steel cylindrical shells. A theoretical model based on one-dimensional planar acoustic wave propagation through multi-layered media is employed for the interpretation of the observed resonance (interference) spectrum. Two analytical methods, derived from the transmission model are used for determination of sound speed, sound attenuation coefficient, and density of liquids from the relative amplitude and half-power peak width of the observed resonance peaks. Effects of the container material and geometrical properties, path-length, wall thickness are also studied. This study shows that the interferometry technique and the experimental method developed are capable of accurate determination of sound speed, sound attenuation, and density in fluids completely noninvasively. It is a capable and versatile fluid characterization technique and has many potential NDE applications.

  11. Photoacoustic tomography based on the Green's function retrieval with ultrasound interferometry for sample partially behind an acoustically scattering layer

    SciTech Connect

    Yin, Jie; Tao, Chao Cai, Peng; Liu, Xiaojun

    2015-06-08

    Acoustically inhomogeneous mediums with multiple scattering are often the nightmare of photoacoustic tomography. In order to break this limitation, a photoacoustic tomography scheme combining ultrasound interferometry and time reversal is proposed to achieve images in acoustically scattering medium. An ultrasound interferometry is developed to determine the unknown Green's function of strong scattering tissue. Using the determined Greens' function, a time-reversal process is carried out to restore images behind an acoustically inhomogeneous layer from the scattering photoacoustic signals. This method effectively decreases the false contrast, noise, and position deviation of images induced by the multiple scattering. Phantom experiment is carried out to validate the method. Therefore, the proposed method could have potential value in extending the biomedical applications of photoacoustic tomography in acoustically inhomogeneous tissue.

  12. Imaging of transient surface acoustic waves by full-field photorefractive interferometry.

    PubMed

    Xiong, Jichuan; Xu, Xiaodong; Glorieux, Christ; Matsuda, Osamu; Cheng, Liping

    2015-05-01

    A stroboscopic full-field imaging technique based on photorefractive interferometry for the visualization of rapidly changing surface displacement fields by using of a standard charge-coupled device (CCD) camera is presented. The photorefractive buildup of the space charge field during and after probe laser pulses is simulated numerically. The resulting anisotropic diffraction upon the refractive index grating and the interference between the polarization-rotated diffracted reference beam and the transmitted signal beam are modeled theoretically. The method is experimentally demonstrated by full-field imaging of the propagation of photoacoustically generated surface acoustic waves with a temporal resolution of nanoseconds. The surface acoustic wave propagation in a 23 mm × 17 mm area on an aluminum plate was visualized with 520 × 696 pixels of the CCD sensor, yielding a spatial resolution of 33 μm. The short pulse duration (8 ns) of the probe laser yields the capability of imaging SAWs with frequencies up to 60 MHz. PMID:26026514

  13. Acoustic interferometry for geoacoustic characterization in a soft-layered sediment environment.

    PubMed

    Ren, Qun-yan; Hermand, Jean-Pierre

    2013-01-01

    The broadband spectrogram of a moving surface ship usually exhibits striations. Their structure is determined by bottom conditions of the shallow water waveguide and can therefore be used for environmental characterization. A two-step acoustic interferometry technique is proposed to estimate main geoacoustic properties of unconsolidated sediment by exploiting local features of the striations. Their positions at low frequencies are first used to detect the changes in sediment properties with respect to a reference sediment and provide a reliable estimation of the changes through the determination of a frequency shift. Then toward higher frequencies, local frequency-range areas with salient striations are selected to refine the solution with their structure features. The technique is tested with passive acoustic ship run data collected southeast of the island of Elba in the Mediterranean Sea in 2007. Data from the four receivers of a shallow sparse vertical array are processed to estimate the thickness and compression wave speed of a soft clay layer overlying a harder bottom. The results from individual receivers are close and agree well with active inversion results and seismic profiles in the same area. Moreover, a better resolution is obtained by combining these results. This method is demonstrated to be robust to source range uncertainties due to the striation stability to its small variation. The good experimental results suggest the technique is an effective tool for mapping the geoacoustic properties of wide coastal areas with easily deployed receiver systems or even one single receiver. PMID:23297885

  14. Active monitoring of formaldehyde diffusion into histological tissues with digital acoustic interferometry.

    PubMed

    Bauer, Daniel R; Stevens, Benjamin; Chafin, David; Theiss, Abbey P; Otter, Michael

    2016-01-01

    The preservation of certain labile cancer biomarkers with formaldehyde-based fixatives can be considerably affected by preanalytical factors such as quality of fixation. Currently, there are no technologies capable of quantifying a fixative's concentration or the formation of cross-links in tissue specimens. This work examined the ability to detect formalin diffusion into a histological specimen in real time. As formaldehyde passively diffused into tissue, an ultrasound time-of-flight (TOF) shift of several nanoseconds was generated due to the distinct sound velocities of formalin and exchangeable fluid within the tissue. This signal was resolved with a developed digital acoustic interferometry algorithm, which compared the phase differential between signals and computed the absolute TOF with subnanosecond precision. The TOF was measured repeatedly across the tissue sample for several hours until diffusive equilibrium was realized. The change in TOF from 6-mm thick ex vivo human tonsil fit a single-exponential decay ([Formula: see text]) with rate constants that varied drastically spatially between 2 and 10 h ([Formula: see text]) due to substantial heterogeneity. This technology may prove essential to personalized cancer diagnostics by documenting and tracking biospecimen preanalytical fixation, guaranteeing their suitability for diagnostic assays, and speeding the workflow in clinical histopathology laboratories. PMID:26866049

  15. A comparison between heterodyne and homodyne interferometry to realise the SI unit of acoustic pressure in water

    NASA Astrophysics Data System (ADS)

    Koukoulas, Triantafillos; Robinson, Stephen; Rajagopal, Srinath; Zeqiri, Bajram

    2016-04-01

    Optical approaches for hydrophone calibrations offer significant advantages over existing methods based on reciprocity. In particular, heterodyne and homodyne interferometry can accurately measure particle velocity and displacements at a specific point in space thus enabling the acoustical pressure to be measured in an absolute, direct, assumption-free manner, with traceability through the SI definition of the metre. The calibration of a hydrophone can then be performed by placing the active element of the sensor at the point where the acoustic pressure field was measured and monitoring its electrical output. However, it is crucial to validate the performance and accuracy of such optical methods by direct comparison rather than through device calibration. Here we report on the direct comparison of two such optical interferometers used in underwater acoustics and ultrasonics in terms of acoustic pressure estimation and their associated uncertainties in the frequency range 200 kHz-3.5 MHz, with results showing agreement better than 1% in terms of pressure and typical expanded uncertainties better than 3% for both reported methods.

  16. Experimental Study of High-Range-Resolution Medical Acoustic Imaging for Multiple Target Detection by Frequency Domain Interferometry

    NASA Astrophysics Data System (ADS)

    Kimura, Tomoki; Taki, Hirofumi; Sakamoto, Takuya; Sato, Toru

    2009-07-01

    We employed frequency domain interferometry (FDI) for use as a medical acoustic imager to detect multiple targets with high range resolution. The phase of each frequency component of an echo varies with the frequency, and target intervals can be estimated from the phase variance. This processing technique is generally used in radar imaging. When the interference within a range gate is coherent, the cross correlation between the desired signal and the coherent interference signal is nonzero. The Capon method works under the guiding principle that output power minimization cancels the desired signal with a coherent interference signal. Therefore, we utilize frequency averaging to suppress the correlation of the coherent interference. The results of computational simulations using a pseudoecho signal show that the Capon method with adaptive frequency averaging (AFA) provides a higher range resolution than a conventional method. These techniques were experimentally investigated and we confirmed the effectiveness of the proposed method of processing by FDI.

  17. Temporal Changes in Eruptive Behavior at Fuego Volcano, Guatemala Identified with Seismic Coda Wave Interferometry and Seismo-acoustic Observations

    NASA Astrophysics Data System (ADS)

    Erdem, J.; Waite, G. P.

    2011-12-01

    Fuego Volcano (14°29'N, 90°53'W, 3800m) is the southernmost vent of the north-south trending Fuego-Acatenango volcanic complex. A basaltic-andesite stratovolcano, Fuego has had more than 60 sub-plinian eruptions since 1524 AD, making it one of the most active volcanoes in the world. Since 1999 Fuego has exhibited continuous low-level activity, which alternates between periods of lava effusion with strombolian explosions and periods of discrete explosions with no lava effusion. We analyzed 138 explosions recorded on a broadband seismometer and infrasonic microphones from 7 to 14 June 2008 at a distance of 7.5 km from the vent. During the observation period, a new lava flow began. Additional observations were made at a distance of 1 km between 27 June and 1 July 2008. The explosions were identified through a combination of visual field observations and the examination of infrasound records. Acoustic waveform cross-correlation indicated a highly repetitive source appropriate for investigating temporal variations in the wavefield. We measured variations in seismic and acoustic wave arrival time differences in the range of 0.5 s for the more distant station, which might occur as a result of variations in source depth, for example. However, after examining a wind speed model for the region, we find that wind speed variations are more likely to explain the delays. We also detected short-term relative changes in the velocity structure ranging from -0.23% to 0.61% at the distant station and -0.8% to 0.7% at the closer station using seismic coda wave interferometry. This rapid variation, sometimes changing by 0.23% in 90 minutes, may indicate minor fluctuations in volatile content.

  18. Quantitative Interferometry in the Severe Acoustic Environment of Resonant Supersonic Jets

    NASA Technical Reports Server (NTRS)

    Mercer, Carolyn R.; Raman, Ganesh

    1999-01-01

    Understanding fundamental fluidic dynamic and acoustic processes in high-speed jets requires quantitative velocity, density and temperature measurements. In this paper we demonstrate a new, robust Liquid Crystal Point Diffraction Interferometer (LCPDI) that includes phase stepping and can provide accurate data even in the presence of intense acoustic fields. This novel common path interferometer (LCPDI) was developed to overcome difficulties with the Mach Zehnder interferometer in vibratory environments and is applied here to the case of a supersonic shock- containing jet. The environmentally insensitive LCPDI that is easy to align and capable of measuring optical wavefronts with high accuracy is briefly described, then integrated line of sight density data from the LCPDI for two underexpanded jets are presented.

  19. Digital stroboscopic holographic interferometry for power flow measurements in acoustically driven membranes

    NASA Astrophysics Data System (ADS)

    Keustermans, William; Pires, Felipe; De Greef, Daniël; Vanlanduit, Steve J. A.; Dirckx, Joris J. J.

    2016-06-01

    Despite the importance of the eardrum and the ossicles in the hearing chain, it remains an open question how acoustical energy is transmitted between them. Identifying the transmission path at different frequencies could lead to valuable information for the domain of middle ear surgery. In this work a setup for stroboscopic holography is combined with an algorithm for power flow calculations. With our method we were able to accurately locate the power sources and sinks in a membrane. The setup enabled us to make amplitude maps of the out-of-plane displacement of a vibrating rubber membrane at subsequent instances of time within the vibration period. From these, the amplitude maps of the moments of force and velocities are calculated. The magnitude and phase maps are extracted from this amplitude data, and form the input for the power flow calculations. We present the algorithm used for the measurements and for the power flow calculations. Finite element models of a circular plate with a local energy source and sink allowed us to test and optimize this algorithm in a controlled way and without the present of noise, but will not be discussed below. At the setup an earphone was connected with a thin tube which was placed very close to the membrane so that sound impinges locally on the membrane, hereby acting as a local energy source. The energy sink was a little piece of foam carefully placed against the membrane. The laser pulses are fired at selected instants within the vibration period using a 30 mW HeNe continuous wave laser (red light, 632.8 nm) in combination with an acousto-optic modulator. A function generator controls the phase of these illumination pulses and the holograms are recorded using a CCD camera. We present the magnitude and phase maps as well as the power flow measurements on the rubber membrane. Calculation of the divergence of this power flow map provides a simple and fast way of identifying and locating an energy source or sink. In conclusion

  20. Characterization of irradiation damage distribution near TiO{sub 2}/SrTiO{sub 3} interfaces using coherent acoustic phonon interferometry

    SciTech Connect

    Yarotski, Dmitry; Yan Li; Jia Quanxi; Taylor, Antoinette J.; Fu Engang; Wang Yongqiang; Uberuaga, Blas P.

    2012-06-18

    We apply ultrafast coherent acoustic phonon interferometry to characterize the distribution of the radiation damage near the TiO{sub 2}/SrTiO{sub 3} interfaces. We show that the optical and mechanical properties of anatase TiO{sub 2} remain unaffected by the radiation dosages in the 0.1 Division-Sign 5 dpa (displacements per atom) range, while the degraded optical response indicates a significant defect accumulation in the interfacial region of SrTiO{sub 3} at 0.1 dpa and subsequent amorphization at 3 dpa. Comparison between the theoretical simulations and the experimental results reveals an almost threefold reduction of the sound velocity in the irradiated SrTiO{sub 3} layer with peak damage levels of 3 and 5 dpa.

  1. Acoustics

    NASA Astrophysics Data System (ADS)

    The acoustics research activities of the DLR fluid-mechanics department (Forschungsbereich Stroemungsmechanik) during 1988 are surveyed and illustrated with extensive diagrams, drawings, graphs, and photographs. Particular attention is given to studies of helicopter rotor noise (high-speed impulsive noise, blade/vortex interaction noise, and main/tail-rotor interaction noise), propeller noise (temperature, angle-of-attack, and nonuniform-flow effects), noise certification, and industrial acoustics (road-vehicle flow noise and airport noise-control installations).

  2. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  3. Non-contact fluid characterization in containers using ultrasonic waves

    DOEpatents

    Sinha, Dipen N.

    2012-05-15

    Apparatus and method for non-contact (stand-off) ultrasonic determination of certain characteristics of fluids in containers or pipes are described. A combination of swept frequency acoustic interferometry (SFAI), wide-bandwidth, air-coupled acoustic transducers, narrowband frequency data acquisition, and data conversion from the frequency domain to the time domain, if required, permits meaningful information to be extracted from such fluids.

  4. Atom Interferometry

    SciTech Connect

    Kasevich, Mark

    2008-05-08

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton's constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gyroscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be used to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  5. Atom Interferometry

    SciTech Connect

    Mark Kasevich

    2008-05-07

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton’s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  6. Atom Interferometry

    ScienceCinema

    Mark Kasevich

    2010-01-08

    Atom de Broglie wave interferometry has emerged as a tool capable of addressing a diverse set of questions in gravitational and condensed matter physics, and as an enabling technology for advanced sensors in geodesy and navigation. This talk will review basic principles, then discuss recent applications and future directions. Scientific applications to be discussed include measurement of G (Newton?s constant), tests of the Equivalence Principle and post-Newtonian gravity, and study of the Kosterlitz-Thouless phase transition in layered superfluids. Technology applications include development of precision gryoscopes and gravity gradiometers. The talk will conclude with speculative remarks looking to the future: Can atom interference methods be sued to detect gravity waves? Can non-classical (entangled/squeezed state) atom sources lead to meaningful sensor performance improvements?

  7. Quantum Interferometry

    NASA Technical Reports Server (NTRS)

    Dowling, Jonathan P.

    2000-01-01

    Recently, several researchers, including yours truly, have been able to demonstrate theoretically that quantum photon entanglement has the potential to also revolutionize the entire field of optical interferometry, by providing many orders of magnitude improvement in interferometer sensitivity. The quantum entangled photon interferometer approach is very general and applies to many types of interferometers. In particular, without nonlocal entanglement, a generic classical interferometer has a statistical-sampling shot-noise limited sensitivity that scales like 1/Sqrt[N], where N is the number of particles (photons, electrons, atoms, neutrons) passing through the interferometer per unit time. However, if carefully prepared quantum correlations are engineered between the particles, then the interferometer sensitivity improves by a factor of Sqrt[N] (square root of N) to scale like 1/N, which is the limit imposed by the Heisenberg Uncertainty Principle. For optical (laser) interferometers operating at milliwatts of optical power, this quantum sensitivity boost corresponds to an eight-order-of-magnitude improvement of signal to noise. Applications are to tests of General Relativity such as ground and orbiting optical interferometers for gravity wave detection, Laser Interferometer Gravity Observatory (LIGO) and the European Laser Interferometer Space Antenna (LISA), respectively.

  8. History of Stellar Interferometry

    NASA Technical Reports Server (NTRS)

    Lawson, Peter R.

    2004-01-01

    This viewgraph presentation reviews the history of stellar interferometry from the suggestion of Fizeau that stellar interferometry was possible,to the use of the Mark I, II and III for astrometry. Photographs, and parts of original articles are presented.

  9. Electronic Speckle Pattern Interferometry

    NASA Astrophysics Data System (ADS)

    Lokberg, Ole J.

    1988-01-01

    The basic principles of electronic speckle pattern interferometry (ESPI) are described, stressing its close similarity to hologram interferometry. The technique's applications for vibration and deformation testing within industrial and medical research are outlined. Future developments are discussed.

  10. Synthetic Aperture Radar Interferometry

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  11. Source-receiver wave field interferometry.

    PubMed

    Curtis, Andrew; Halliday, David

    2010-04-01

    Correlation or convolution of recordings of diffuse fields at a pair of locations have been shown to result in estimates of the Green's function between the two locations. Variously referred to as wave field or seismic interferometry in different fields of research, Green's functions can thus be constructed between either pairs of receivers or pairs of energy sources. Proofs of these results rely on representation theorems. We show how to derive three acoustic and elastic representation theorems that unify existing correlational and convolutional approaches. We thus derive three forms of interferometry that provide Green's functions on source-to-receiver paths, using only energy that has propagated from surrounding sources or to surrounding receivers. The three forms correspond to three possible canonical geometries. We thus allow interferometric theory and methods to be applied to commonly used source-receiver configurations. PMID:20481847

  12. Holograph and Interferometry.

    ERIC Educational Resources Information Center

    Altman, Thomas C.

    1992-01-01

    Describes a method to create holograms for use in different interferometry techniques. Students utilize these techniques in experiments to study the structural integrity of a clarinet reed and the effects of temperature on objects. (MDH)

  13. PALSAR SCANSAR SCANSAR Interferometry

    NASA Astrophysics Data System (ADS)

    Shimada, Masanobu

    2008-11-01

    We have examined the capability of the PALSAR SCANSAR SCANSAR interferometry by observing the African forest and Sahara desert, both of which are separated 46 days in March and April of 2008. These two paths are well tuned for the orbital tube of 200m and the beam synchronization of the transmission positions in 200m to 500m, we have succeeded the PALSAR SCANSAR SCANSAR interferometry and achieved the detection of the height information. We will report the results in this paper.

  14. LISA Long-Arm Interferometry

    NASA Technical Reports Server (NTRS)

    Thorpe, James I.

    2009-01-01

    An overview of LISA Long-Arm Interferometry is presented. The contents include: 1) LISA Interferometry; 2) Constellation Design; 3) Telescope Design; 4) Constellation Acquisition; 5) Mechanisms; 6) Optical Bench Design; 7) Phase Measurement Subsystem; 8) Phasemeter Demonstration; 9) Time Delay Interferometry; 10) TDI Limitations; 11) Active Frequency Stabilization; 12) Spacecraft Level Stabilization; 13) Arm-Locking; and 14) Embarassment of Riches.

  15. Interferometry science center

    NASA Technical Reports Server (NTRS)

    Sargent, A. I.

    2002-01-01

    The Interferometry Science Center (ISC) is operated jointly by Caltech and JPL and is part of NASA's Navigator Program. The ISC has been created to facilitate the timely and successful execution of scientific investigations within the Navigator program, particularly those that rely on observations from NASA's interferometer projects. Currently, ISC is expected to provide full life cycle support for the Keck Interferometer, the Starlight mission, the Space Interferometry Mission, and the Terrestrial Planet Finder Mission. The nature and goals of ISc will be described.

  16. Coda wave interferometry for estimating nonlinear behavior in seismic velocity.

    PubMed

    Snieder, Roel; Grêt, Alexandre; Douma, Huub; Scales, John

    2002-03-22

    In coda wave interferometry, one records multiply scattered waves at a limited number of receivers to infer changes in the medium over time. With this technique, we have determined the nonlinear dependence of the seismic velocity in granite on temperature and the associated acoustic emissions. This technique can be used in warning mode, to detect the presence of temporal changes in the medium, or in diagnostic mode, where the temporal change in the medium is quantified. PMID:11910107

  17. Acoustic neuroma

    MedlinePlus

    Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor ... Acoustic neuromas have been linked with the genetic disorder neurofibromatosis type 2 (NF2). Acoustic neuromas are uncommon.

  18. Simultaneous Immersion Mirau Interferometry

    NASA Astrophysics Data System (ADS)

    Lyulko, Oleksandra

    The present work describes a novel imaging technique for label-free no-UV vibration-insensitive imaging of live cells in an epi-illumination geometry. This technique can be implemented in a variety of imaging applications. For example, it can be used for cell targeting as a part of a platform for targeted cell irradiations - single-cell microbeam. The goal of microbeam facilities is to provide biological researchers with tools to study the effects of ionizing radiation on live cells. A common way of cell labeling - fluorescent staining - may alter cellular metabolism and UV illumination presents potential damage for the genetic material. The new imaging technique will allow the researchers to separate radiation-induced effects from the effects caused by confounding factors like fluorescent staining or UV light. Geometry of irradiation endstations at some microbeam facilities precludes the use of transmitted light, e.g. in the Columbia University's Radiological Research Accelerator Facility microbeam endstation, where the ion beam exit window is located just below the sample. Imaging techniques used at such endstations must use epi-illumination. Mirau Interferometry is an epi-illumination, non-stain imaging modality suitable for implementation at a microbeam endstation. To facilitate interferometry and to maintain cell viability, it is desirable that cells stay in cell growth medium during the course of an experiment. To accommodate the use of medium, Immersion Mirau Interferometry has been developed. A custom attachment for a microscope objective has been designed and built for interferometric imaging with the possibility of immersion of the apparatus into cell medium. The implemented data collection algorithm is based on the principles of Phase-Shifting Interferometry. The largest limitation of Phase-Shifting Interferometry is its sensitivity to the vertical position of the sample. In environments where vibration isolation is difficult, this makes image

  19. Digitally Enhanced Heterodyne Interferometry

    NASA Technical Reports Server (NTRS)

    Shaddock, Daniel; Ware, Brent; Lay, Oliver; Dubovitsky, Serge

    2010-01-01

    Spurious interference limits the performance of many interferometric measurements. Digitally enhanced interferometry (DEI) improves measurement sensitivity by augmenting conventional heterodyne interferometry with pseudo-random noise (PRN) code phase modulation. DEI effectively changes the measurement problem from one of hardware (optics, electronics), which may deteriorate over time, to one of software (modulation, digital signal processing), which does not. DEI isolates interferometric signals based on their delay. Interferometric signals are effectively time-tagged by phase-modulating the laser source with a PRN code. DEI improves measurement sensitivity by exploiting the autocorrelation properties of the PRN to isolate only the signal of interest and reject spurious interference. The properties of the PRN code determine the degree of isolation.

  20. A LISA Interferometry Primer

    NASA Technical Reports Server (NTRS)

    Thorpe, James Ira

    2010-01-01

    A key challenge for all gravitational wave detectors in the detection of changes in the fractional difference between pairs of test masses with sufficient precision to measure astrophysical strains with amplitudes on the order of approx.10(exp -21). ln the case of the five million km arms of LISA, this equates to distance measurements on the ten picometer level. LISA interferometry utilizes a decentralized topology, in which each of the sciencecraft houses its own light sources, detectors, and electronics. The measurements made at each of the sciencecraft are then telemetered to ground and combined to extract the strain experienced by the constellation as a whole. I will present an overview of LISA interferometry and highlight some of the key components and technologies that make it possible.

  1. Null Stellar Intensity Interferometry

    NASA Astrophysics Data System (ADS)

    Tan, P. K.; Chia, C. M.; Han, W. D.; Chan, A. H.; Kurtsiefer, C.

    2014-04-01

    Since the discovery of the first exoplanet in 1989, though over 850 candidates have been verified (Schneider 2012), few are similar to our Earth in terms of mass and size. Hence here we would like to propose the revival and improvement of optical intensity interferometry to achieve sub-milliarcsecond resolution, which promises also to be less sensitive to weather conditions, light pollution and optomechanical alignments, yet only requiring baselines <100m.

  2. Spatial interferometry in optical astronomy

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    A bibliographic guide is presented to publications of spatial interferometry techniques applied to optical astronomy. Listings appear in alphabetical order, by first author, as well as in specific subject categories listed in chronological order, including imaging theory and speckle interferometry, experimental techniques, and observational results of astronomical studies of stars, the Sun, and the solar system.

  3. Deflectometry vs. interferometry

    NASA Astrophysics Data System (ADS)

    Häusler, Gerd; Faber, Christian; Olesch, Evelyn; Ettl, Svenja

    2013-04-01

    Quantitative deflectometry is a new tool to measure specular surfaces. The spectrum of measurable surfaces ranges from flat to freeform surfaces with steep slopes, with a size ranging from millimeters to several meters. We illustrate this by several applications: eye glass measurements, measurements of big mirrors, and in-line measurements in ultra-precision manufacturing without unclamping of the sample. We describe important properties of deflectometry and compare its potentials and limitations with interferometry. We discuss which method is superior for which application and how the potential of deflectometry may be developing in the future.

  4. Complex master slave interferometry.

    PubMed

    Rivet, Sylvain; Maria, Michael; Bradu, Adrian; Feuchter, Thomas; Leick, Lasse; Podoleanu, Adrian

    2016-02-01

    A general theoretical model is developed to improve the novel Spectral Domain Interferometry method denoted as Master/Slave (MS) Interferometry. In this model, two functions, g and h are introduced to describe the modulation chirp of the channeled spectrum signal due to nonlinearities in the decoding process from wavenumber to time and due to dispersion in the interferometer. The utilization of these two functions brings two major improvements to previous implementations of the MS method. A first improvement consists in reducing the number of channeled spectra necessary to be collected at Master stage. In previous MSI implementation, the number of channeled spectra at the Master stage equated the number of depths where information was selected from at the Slave stage. The paper demonstrates that two experimental channeled spectra only acquired at Master stage suffice to produce A-scans from any number of resolved depths at the Slave stage. A second improvement is the utilization of complex signal processing. Previous MSI implementations discarded the phase. Complex processing of the electrical signal determined by the channeled spectrum allows phase processing that opens several novel avenues. A first consequence of such signal processing is reduction in the random component of the phase without affecting the axial resolution. In previous MSI implementations, phase instabilities were reduced by an average over the wavenumber that led to reduction in the axial resolution. PMID:26906857

  5. Time-Delay Interferometry

    NASA Astrophysics Data System (ADS)

    Dhurandhar, Sanjeev V.; Tinto, Massimo

    2005-07-01

    Equal-arm interferometric detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is differenced at the photo detector. In this situation, much lower level secondary noises then set the overall performance. If, however, the two arms have different lengths (as will necessarily be the case with space-borne interferometers), the laser noise experiences different delays in the two arms and will hence not directly cancel at the detector. In order to solve this problem, a technique involving heterodyne interferometry with unequal arm lengths and independent phase-difference readouts has been proposed. It relies on properly time-shifting and linearly combining independent Doppler measurements, and for this reason it has been called Time-Delay Interferometry (TDI). This article provides an overview of the theory and mathematical foundations of TDI as it will be implemented by the forthcoming space-based interferometers such as the Laser Interferometer Space Antenna (LISA) mission. We have purposely left out from this first version of our "Living Review" article on TDI all the results of more practical and experimental nature, as well as all the aspects of TDI that the data analysts will need to account for when analyzing the LISA TDI data combinations. Our forthcoming "second edition" of this review paper will include these topics.

  6. Intellectual property in holographic interferometry

    NASA Astrophysics Data System (ADS)

    Reingand, Nadya; Hunt, David

    2006-08-01

    This paper presents an overview of patents and patent applications on holographic interferometry, and highlights the possibilities offered by patent searching and analysis. Thousands of patent documents relevant to holographic interferometry were uncovered by the study. The search was performed in the following databases: U.S. Patent Office, European Patent Office, Japanese Patent Office and Korean Patent Office for the time frame from 1971 through May 2006. The patent analysis unveils trends in patent temporal distribution, patent families formation, significant technological coverage within the market of system that employ holographic interferometry and other interesting insights.

  7. Deep frequency modulation interferometry.

    PubMed

    Gerberding, Oliver

    2015-06-01

    Laser interferometry with pm/Hz precision and multi-fringe dynamic range at low frequencies is a core technology to measure the motion of various objects (test masses) in space and ground based experiments for gravitational wave detection and geodesy. Even though available interferometer schemes are well understood, their construction remains complex, often involving, for example, the need to build quasi-monolithic optical benches with dozens of components. In recent years techniques have been investigated that aim to reduce this complexity by combining phase modulation techniques with sophisticated digital readout algorithms. This article presents a new scheme that uses strong laser frequency modulations in combination with the deep phase modulation readout algorithm to construct simpler and easily scalable interferometers. PMID:26072834

  8. Shaken lattice interferometry

    NASA Astrophysics Data System (ADS)

    Weidner, Carrie; Yu, Hoon; Anderson, Dana

    2016-05-01

    In this work, we report on progress towards performing interferometry using atoms trapped in an optical lattice. That is, we start with atoms in the ground state of an optical lattice potential V(x) =V0cos [ 2 kx + ϕ(t) ] , and by a prescribed phase function ϕ(t) , transform from one atomic wavefunction to another. In this way, we implement the standard interferometric sequence of beam splitting, propagation, reflection, reverse propagation, and recombination. Through the use of optimal control techniques, we have computationally demonstrated a scalable accelerometer that provides information on the sign of the applied acceleration. Extension of this idea to a two-dimensional shaken-lattice-based gyroscope is discussed. In addition, we report on the experimental implementation of the shaken lattice system.

  9. Spectroscopic Low Coherence Interferometry

    NASA Astrophysics Data System (ADS)

    Bosschaart, Nienke; van Leeuwen, T. G.; Aalders, Maurice C.; Hermann, Boris; Drexler, Wolfgang; Faber, Dirk J.

    Low-coherence interferometry (LCI) allows high-resolution volumetric imaging of tissue morphology and provides localized optical properties that can be related to the physiological status of tissue. This chapter discusses the combination of spatial and spectroscopic information by means of spectroscopic OCT (sOCT) and low-coherence spectroscopy (LCS). We describe the theory behind these modalities for the assessment of spatially resolved optical absorption and (back)scattering coefficient spectra. These spectra can be used for the highly localized quantification of chromophore concentrations and assessment of tissue organization on (sub)cellular scales. This leads to a wealth of potential clinical applications, ranging from neonatology for the determination of billibrubin concentrations, to oncology for the optical assessment of the aggressiveness of a cancerous lesion.

  10. Portable intensity interferometry

    NASA Astrophysics Data System (ADS)

    Horch, Elliott P.; Camarata, Matthew A.

    2012-07-01

    A limitation of the current generation of long baseline optical interferometers is the need to make the light interfere prior to detection. This is unlike the radio regime where signals can be recorded fast enough to use electronics to accomplish the same result. This paper describes a modern optical intensity interferometer based on electronics with picosecond timing resolution. The instrument will allow for portable optical interferometry with much larger baselines than currently possible by using existing large telescopes. With modern electronics, the limiting magnitude of the technique at a 4-m aperture size becomes competitive with some amplitude-based interferometers. The instrumentation will permit a wireless mode of operation with GPS clocking technology, extending the work to extremely large baselines. We discuss the basic observing strategy, a planned observational program at the Lowell Observatory 1.8-m and 1.0-m telescopes, and the science that can realistically be done with this instrumentation.

  11. Interferometry for rotating sources

    NASA Astrophysics Data System (ADS)

    Velle, S.; Mehrabi Pari, S.; Csernai, L. P.

    2016-06-01

    The two particle interferometry method to determine the size of the emitting source after a heavy ion collision is extended. Following the extension of the method to spherical expansion dynamics, here we extend the method to rotating systems. It is shown that rotation of a cylindrically symmetric system leads to modifications, which can be perceived as spatial asymmetry by the "azimuthal HBT" method. We study an exact rotating and expanding solution of the fluid dynamical model of heavy ion reactions. We consider a source that is azimuthally symmetric in space around the axis of rotation, and discuss the features of the resulting two particle correlation function. This shows the azimuthal asymmetry arising from the rotation. We show that this asymmetry leads to results similar to those given by spatially asymmetric sources.

  12. Optical Long Baseline Interferometry News

    NASA Astrophysics Data System (ADS)

    Lawson, P. R.; Malbet, F.

    2005-12-01

    The Optical Long Baseline Interferometry News is a website and forum for scientists, engineers, and students who share an interest in long baseline stellar interferometry. It was established in 1995 and is the focus of activity of the IAU Working Group on Optical/Infrared Interferometry. Here you will find links to projects devoted to stellar interferometry, news items, recent papers and preprints, and resources for further research. The email news forum was established in 2001 to complement the website and to facilitate exchanges and collaborations. The forum includes an email exploder and an archived list of discussions. You are invited to explore the forum and website at http://olbin.jpl.nasa.gov. Work by PRL was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  13. Seismic interferometry for temporal monitoring

    NASA Astrophysics Data System (ADS)

    Nakata, Norimitsu

    Seismic interferometry, where one computes coherency of waves between two or more receivers and averages over many sources, is a technique of signal processing to reconstruct wavefields. This technique is used in geophysics, especially exploration geophysics and seismology. After more than a half century from the first study related to seismic interferometry (although the name of seismic interferometry has been used for approximately the last 15 years), researchers have developed this technique for many aspects: using multiples for increasing illuminations, enhancement of survey areas, ambient-noise analysis, and removal of the imprint of a complicated overburden. In this dissertation, I focus on the advantages of seismic interferometry for time-lapse measurements. Measurements of temporal changes yield beneficial information of fluid flow, crustal deformation, temperature, and/or stress. Estimation of temporal changes using active sources is, however, technically and economically challenging. Because seismic interferometry reconstruct waves that would have been recorded with a repeatable active sources using only receivers, this technique is appropriate for temporal monitoring. With seismic interferometry, one obtains some advantages that include canceling the complexity of wave propagation to a virtual source, creating virtual shear-wave (S-wave) sources (active S sources are expensive), and using waves that are not usable for active sources (e.g., ambient noise and multiples). I seek applications of seismic interferometry in a variety of topics (i.e., seismology, structural engineering, and exploration geophysics), and develop and/or modify several techniques of seismic interferometry for each application. Some chapters focus on developing techniques of seismic interferometry, and other chapters aim to estimate and interpret temporal changes with the developed techniques. For passive seismic sources, deconvolution-based seismic interferometry has better

  14. High-speed imaging of sound using parallel phase-shifting interferometry.

    PubMed

    Ishikawa, Kenji; Yatabe, Kohei; Chitanont, Nachanant; Ikeda, Yusuke; Oikawa, Yasuhiro; Onuma, Takashi; Niwa, Hayato; Yoshii, Minoru

    2016-06-13

    Sound-field imaging, the visualization of spatial and temporal distribution of acoustical properties such as sound pressure, is useful for understanding acoustical phenomena. This study investigated the use of parallel phase-shifting interferometry (PPSI) with a high-speed polarization camera for imaging a sound field, particularly high-speed imaging of propagating sound waves. The experimental results showed that the instantaneous sound field, which was generated by ultrasonic transducers driven by a pure tone of 40 kHz, was quantitatively imaged. Hence, PPSI can be used in acoustical applications requiring spatial information of sound pressure. PMID:27410311

  15. Optical Interferometry Motivation and History

    NASA Technical Reports Server (NTRS)

    Lawson, Peter

    2006-01-01

    A history and motivation of stellar interferometry is presented. The topics include: 1) On Tides, Organ Pipes, and Soap Bubbles; 2) Armand Hippolyte Fizeau (1819-1896); 3) Fizeau Suggests Stellar Interferometry 1867; 4) Edouard Stephan (1837-1923); 5) Foucault Refractor; 6) Albert A. Michelson (1852-1931); 7) On the Application of Interference Methods to Astronomy (1890); 8) Moons of Jupiter (1891); 9) Other Applications in 19th Century; 10) Timeline of Interferometry to 1938; 11) 30 years goes by; 12) Mount Wilson Observatory; 13) Michelson's 20 ft Interferometer; 14) Was Michelson Influenced by Fizeau? 15) Work Continues in the 1920s and 30s; 16) 50 ft Interferometer (1931-1938); 17) Light Paths in the 50 ft Interferometer; 18) Ground-level at the 50 ft; 19) F.G. Pease (1881-1938); 20) Timeline of Optical Interferometry to 1970; 21) A New Type of Stellar Interferometer (1956); 22) Intensity Interferometer (1963- 1976; 23) Robert Hanbury Brown; 24) Interest in Optical Interferometry in the 1960s; 25) Interferometry in the Early 1970s; and 26) A New Frontier is Opened up in 1974.

  16. Extreme ultraviolet interferometry

    SciTech Connect

    Goldberg, K A

    1997-12-01

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

  17. Internal stress determination in a polymer composite by Coda wave interferometry

    NASA Astrophysics Data System (ADS)

    Zhu, Q.; Binetruy, C.; Burtin, C.

    2016-07-01

    Coda wave interferometry (CWI) is largely employed in geotechnical applications to monitor changes due to cracks in materials but it is still not used for composite materials. In this paper, the technique is proposed to study internal stresses in a composite laminate [0°/90°]63 and was compared with the traditional acoustic technique. It is shown that the Coda wave interferometry has better precision and sensibility than the method based on the first arriving time of flight (TOF) measurement, especially when the fiber orientation is normal to the wave propagation. This method is found to be promising for residual stress evaluation in composite materials.

  18. Preview of Blackbeard interferometry

    SciTech Connect

    Carter, M.J.

    1992-09-01

    Blackbeard is a broadband VHF measurements satellite experiment designed and built by the Space Science and Technology division of the Los Alamos National Laboratory. Blackbeard is a piggy-back experiment on the ALEXIS satellite to be launched into a 70 degree inclination orbit at an altitude of 750 km. The satellite experimental operation and data retrieval are controlled through a telemetry link from the Satellite Operations Center (SOC) located at Los Alamos, NM. The primary experimental objectives of Blackbeard are three-fold: (1) Study the dispersion of broad-band impulsive electromagnetic signals -- in particular, the higher-order amplitude and phase distortion due to propagation through the ionosphere. These depend on ionospheric conditions and irregularities. (2) Utilize RF interferometry and scintillation techniques in the low VHF-band to determine the size and extent of ionospheric irregularities and wave structure -- both natural and artificially induced. This narrow-band data will be used to categorize the ionospheric media as undisturbed, oscillatory, or turbulent. These parameters will then be input into transfer function simulations for broad-band propagation and compared with broad-band propagation data from Blackbeard. (3) Survey and characterize background noise in the VHF-band-consisting of (1) cataloging broadcast amplitudes and signatures and mapping their global pattern, and (2) cataloging the signatures of lightning events. Also, correlate emissions in the visible and VHF bands in an attempt to confirm broad-band RF emissions assumed to be associated with lightning.

  19. Preview of Blackbeard interferometry

    SciTech Connect

    Carter, M.J.

    1992-01-01

    Blackbeard is a broadband VHF measurements satellite experiment designed and built by the Space Science and Technology division of the Los Alamos National Laboratory. Blackbeard is a piggy-back experiment on the ALEXIS satellite to be launched into a 70 degree inclination orbit at an altitude of 750 km. The satellite experimental operation and data retrieval are controlled through a telemetry link from the Satellite Operations Center (SOC) located at Los Alamos, NM. The primary experimental objectives of Blackbeard are three-fold: (1) Study the dispersion of broad-band impulsive electromagnetic signals -- in particular, the higher-order amplitude and phase distortion due to propagation through the ionosphere. These depend on ionospheric conditions and irregularities. (2) Utilize RF interferometry and scintillation techniques in the low VHF-band to determine the size and extent of ionospheric irregularities and wave structure -- both natural and artificially induced. This narrow-band data will be used to categorize the ionospheric media as undisturbed, oscillatory, or turbulent. These parameters will then be input into transfer function simulations for broad-band propagation and compared with broad-band propagation data from Blackbeard. (3) Survey and characterize background noise in the VHF-band-consisting of (1) cataloging broadcast amplitudes and signatures and mapping their global pattern, and (2) cataloging the signatures of lightning events. Also, correlate emissions in the visible and VHF bands in an attempt to confirm broad-band RF emissions assumed to be associated with lightning.

  20. Highspeed multiplexed heterodyne interferometry.

    PubMed

    Isleif, Katharina-S; Gerberding, Oliver; Köhlenbeck, Sina; Sutton, Andrew; Sheard, Benjamin; Goßler, Stefan; Shaddock, Daniel; Heinzel, Gerhard; Danzmann, Karsten

    2014-10-01

    Digitally enhanced heterodyne interferometry is a metrology technique that uses pseudo-random noise codes for modulating the phase of the laser light. Multiple interferometric signals from the same beam path can thereby be isolated based on their propagation delay, allowing one to use advantageous optical layouts in comparison to classic laser interferometers. We present here a high speed version of this technique for measuring multiple targets spatially separated by only a few centimetres. This allows measurements of multiplexed signals using free beams, making the technique attractive for several applications requiring compact optical set-ups like for example space-based interferometers. In an experiment using a modulation and sampling rate of 1.25 GHz we are able to demonstrate multiplexing between targets only separated by 36 cm and we achieve a displacement measurement noise floor of <3 pm/√Hz at 10 Hz between them. We identify a limiting excess noise at low frequencies which is unique to this technique and is probably caused by the finite bandwidth in our measurement set-up. Utilising an active clock jitter correction scheme we are also able to reduce this noise in a null measurement configuration by one order of magnitude. PMID:25322043

  1. Shaken Lattice Interferometry

    NASA Astrophysics Data System (ADS)

    Weidner, Carrie; Yu, Hoon; Anderson, Dana

    2015-05-01

    This work introduces a method to perform interferometry using atoms trapped in an optical lattice. Starting at t = 0 with atoms in the ground state of a lattice potential V(x) =V0cos [ 2 kx + ϕ(t) ] , we show that it is possible to transform from one atomic wavefunction to another by a prescribed shaking of the lattice, i.e., by an appropriately tailored time-dependent phase shift ϕ(t) . In particular, the standard interferometer sequence of beam splitting, propagation, reflection, reverse propagation, and recombination can be achieved via a set of phase modulation operations {ϕj(t) } . Each ϕj(t) is determined using a learning algorithm, and the split-step method calculates the wavefunction dynamics. We have numerically demonstrated an interferometer in which the shaken wavefunctions match the target states to better than 1 % . We carried out learning using a genetic algorithm and optimal control techniques. The atoms remain trapped in the lattice throughout the full interferometer sequence. Thus, the approach may be suitable for use in an dynamic environment. In addition to the general principles, we discuss aspects of the experimental implementation. Supported by the Office of Naval Research (ONR) and Northrop Grumman.

  2. 100-Picometer Interferometry for EUVL

    SciTech Connect

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

    2002-03-18

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

  3. Three-color differential interferometry.

    PubMed

    Desse, J M

    1997-10-01

    It is shown that differential interferometry using a Wollaston prism and a three-color laser source is an optical technique that has all the advantages of differential interferometry in polarized white light and of classical monochromatic interferometry. The interference fringe pattern obtained is very large and colored and presents a central white fringe that enables easy identification of the zero order of the interferogram. The three-color source is obtained by filtering the unwanted lines of the ionized laser (mixed argon and krypton) and balancing the three red, green, and blue lines by a technique that involves placing birefringent plates between the polarizer and the analyzer, the thickness of which has been calculated to create a natural filter. The unsteady aerodynamic flow downstream of a diamond shape airfoil has been visualized with this technique, which shows that the power of the light source is sufficient to record the interferograms at a high rate. PMID:18264221

  4. Techniques in Broadband Interferometry

    SciTech Connect

    Erskine, D J

    2004-01-04

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

  5. Coarse frequency comb interferometry

    NASA Astrophysics Data System (ADS)

    Schwider, J.

    2008-08-01

    Real wedge interferometers of the Fizeau-type do not allow for fringes in case of a spectral broad band source - or in short: for white light fringes. Here, the use of a suitable frequency comb source will help to overcome this limitation on the one hand and on the other will offer the capability for enhanced phase sensitivity in high precision measurements of surface deviations. Frequency combs can be produced either by using a pulse train from a fs-laser or by passive filtering of the light emitted by a broad band source as a superlum-diode or a fs-laser. The frequency comb produced by a common fs-laser is extremely fine, i.e., the frequency difference of consecutive peaks is very small or the distance of consecutive pulses of the pulse train might be of the order of 1m. Therefore, the coarse pulse train produced by passive filtering of a broad band source is better adapted to the needs of surface testing interferometers. White light fringes are either applied for the profiling of discontinuous surfaces and/or can serve as an indication for the correct choice of multiplication factors in superposition interferometry. During the last decennium it became more and more clear that spatially incoherent sources provide better measuring accuracy in surface measurements due to the reduced influence of dust diffraction patterns. The advantage of laser illumination can nevertheless be maintained if the laser light is made spatially incoherent through moving scatterers in the light path. Here, we will discuss the application of spatially incoherent broad band light frequency filtered through a Fabry-Perot filter. The main applications are in the following fields: (1) surface profiling applications using two-beam Fizeau interferometers, (2) selection of single cavities out of a series of interlaced cavities, and (3) sensitivity enhancement for multi-beam interferometers for planeness or sphericity measurements. Some of the discussed possibilities will be experimentally

  6. Atom Interferometry on Sounding Rockets

    NASA Astrophysics Data System (ADS)

    Seidel, S. T.; Lachmann, M. D.; Becker, D.; Grosse, J.; Popp, M. A.; Wang, J. B.; Wendrich, T.; Rasel, E. M.; Quantus Collaboration

    2015-09-01

    Atom interferometry in microgravity offers the possibility to perform high precision measurements of inertial forces complementary to experiments based on classical test masses. The ultimate goal is to perform these quantum measurements in space on board dedicated satellite missions. To reach this, a series of pathfinder microgravity experiments with cold atoms were build. The latest installment of these are conducted on sounding rockets. Here we give a short motivation of atom interferometry in space, an overview of the techniques used, and an introduction of the current mission MAIUS- 1.

  7. High-Speed Digital Interferometry

    NASA Technical Reports Server (NTRS)

    De Vine, Glenn; Shaddock, Daniel A.; Ware, Brent; Spero, Robert E.; Wuchenich, Danielle M.; Klipstein, William M.; McKenzie, Kirk

    2012-01-01

    Digitally enhanced heterodyne interferometry (DI) is a laser metrology technique employing pseudo-random noise (PRN) codes phase-modulated onto an optical carrier. Combined with heterodyne interferometry, the PRN code is used to select individual signals, returning the inherent interferometric sensitivity determined by the optical wavelength. The signal isolation arises from the autocorrelation properties of the PRN code, enabling both rejection of spurious signals (e.g., from scattered light) and multiplexing capability using a single metrology system. The minimum separation of optical components is determined by the wavelength of the PRN code.

  8. Acoustics of old Asian bells

    NASA Astrophysics Data System (ADS)

    Rossing, Thomas D.

    2001-05-01

    The art of casting bronze bells developed to a high level of sophistication in China during the Shang dynasty (1766-1123 BC). Many chimes of two-tone bells remain from the Western and Eastern Zhou dynasties (1122-249 BC). With the spread of Buddhism from the third century, large round temple bells developed in China and later in Korea, Japan, and other Asian countries. Vibrational modes of some of these bells have been studied by means of holographic interferometry and experimental modal testing. Their musical as well as acoustical properties are discussed.

  9. Acoustic Neuroma

    MedlinePlus

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

  10. Acoustic Seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

  11. Acoustic seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

  12. The Space Interferometry Mission

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen C.

    1998-01-01

    The Space Interferometry Mission (SIM) is the next major space mission in NASA's Origins program after SIRTF. The SIM architecture uses three Michelson interferometers in low-earth orbit to provide 4 microarcsecond precision absolute astrometric measurements on approx. 40,000 stars. SIM will also provide synthesis imaging in the visible waveband to a resolution of 10 milliarcsecond, and interferometric nulling to a depth of 10(exp -4). A near-IR (1-2 micron) capability is being considered. Many key technologies will be demonstrated by SIM that will be carried over directly or can be readily scaled to future Origins missions such as TPF. The SIM spacecraft will carry a triple Michelson interferometer with baselines in the 10 meter range. Two interferometers act as high precision trackers, providing attitude information at all time, while the third one conducts the science observations. Ultra-accurate laser metrology and active systems monitor the systematic errors and to control the instrument vibrations in order to reach the 4 microarcsecond level on wide-angle measurements. SIM will produce a wealth of new astronomical data. With an absolute positional precision of 4 microarcsecond, SIM will improve on the best currently available measures (the Hipparcos catalog) by 2 or 3 orders of magnitude, providing parallaxes accurate to 10% and transverse velocities to 0.2 km/s anywhere in the Galaxy, to stars as faint as 20th magnitude. With the addition of radial velocities, knowledge of the 6-dimension phase space for objects of interest will allow us to attack a wide array of previously inaccessible problems such as: search for planets down to few earth masses; calibration of stellar luminosities and by means of standard candles, calibration of the cosmic distance scale; detecting perturbations due to spiral arms, disk warps and central bar in our galaxy; probe of the gravitational potential of the Galaxy, several kiloparsecs out of the galactic plane; synthesis imaging

  13. Meteorology Gauges for Spatial Interferometry

    NASA Technical Reports Server (NTRS)

    Gursel, Y.

    1996-01-01

    Heterodyne interferometers have been commercially available for many years. In addition, many versions have been built at JPL for various projects. This activity is aimed at improving the accuracy of such interferometers from the 1-30 nanometer level to the picometer level for use in the proposes Stellar Interferometry Mission (SIM) as metrology gauges.

  14. Retrieving time-dependent Green's functions in optics with low-coherence interferometry.

    PubMed

    Badon, Amaury; Lerosey, Geoffroy; Boccara, Albert C; Fink, Mathias; Aubry, Alexandre

    2015-01-16

    We report on the passive measurement of time-dependent Green's functions in the optical frequency domain with low-coherence interferometry. Inspired by previous studies in acoustics and seismology, we show how the correlations of a broadband and incoherent wave field can directly yield the Green's functions between scatterers of a complex medium. Both the ballistic and multiple scattering components of the Green's function are retrieved. This approach opens important perspectives for optical imaging and characterization in complex scattering media. PMID:25635547

  15. Topological Acoustics

    NASA Astrophysics Data System (ADS)

    Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

    2015-03-01

    The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers.

  16. Topological acoustics.

    PubMed

    Yang, Zhaoju; Gao, Fei; Shi, Xihang; Lin, Xiao; Gao, Zhen; Chong, Yidong; Zhang, Baile

    2015-03-20

    The manipulation of acoustic wave propagation in fluids has numerous applications, including some in everyday life. Acoustic technologies frequently develop in tandem with optics, using shared concepts such as waveguiding and metamedia. It is thus noteworthy that an entirely novel class of electromagnetic waves, known as "topological edge states," has recently been demonstrated. These are inspired by the electronic edge states occurring in topological insulators, and possess a striking and technologically promising property: the ability to travel in a single direction along a surface without backscattering, regardless of the existence of defects or disorder. Here, we develop an analogous theory of topological fluid acoustics, and propose a scheme for realizing topological edge states in an acoustic structure containing circulating fluids. The phenomenon of disorder-free one-way sound propagation, which does not occur in ordinary acoustic devices, may have novel applications for acoustic isolators, modulators, and transducers. PMID:25839273

  17. Optical and Infrared Interferometry IV

    NASA Astrophysics Data System (ADS)

    Rajagopal, Jayadev K.; Creech-Eakman, Michelle J.; Malbet, Fabien

    2014-08-01

    Optical and IR Interferometry IV at the SPIE 2014 symposium in Montreal had a strong and vibrant program. After initial fears about budget cuts and travel-funding constraints, the Program Committee had to work hard to accommodate as many quality submissions as possible. Innovative, creative and visionary work ensured that the field has progressed well, despite the bleak funding climate felt in the US, Europe and elsewhere. Montreal proved an excellent venue for this, the largest of Interferometry conferences and the only one that brings together practitioners from the world over. Let us summarize a few highlights to convey a glimpse of the excitement that is detailed in the rest of these Proceedings.

  18. Precision Geodesy via Radio Interferometry.

    PubMed

    Hinteregger, H F; Shapiro, I I; Robertson, D S; Knight, C A; Ergas, R A; Whitney, A R; Rogers, A E; Moran, J M; Clark, T A; Burke, B F

    1972-10-27

    Very-long-baseline interferometry experiments, involving observations of extragalactic radio sources, were performed in 1969 to determine the vector separations between antenna sites in Massachusetts and West Virginia. The 845.130-kilometer baseline was estimated from two separate experiments. The results agreed with each other to within 2 meters in all three components and with a special geodetic survey to within 2 meters in length; the differences in baseline direction as determined by the survey and by interferometry corresponded to discrepancies of about 5 meters. The experiments also yielded positions for nine extragalactic radio sources, most to within 1 arc second, and allowed the hydrogen maser clocks at the two sites to be synchronized a posteriori with an uncertainty of only a few nanoseconds. PMID:17815361

  19. Virtually calibrated projection moire interferometry.

    PubMed

    Kimber, Mark; Blotter, Jonathan

    2005-05-01

    Projection moire interferometry (PMI) is an out-of-plane displacement measurement technique that consists of differencing reference and deformed images of a grid pattern projected onto the test object. In conventional PMI, a tedious process of computing the fringe sensitivity coefficient (FSC), which requires moving the test object or the reference plane to known displacements, is used. We present a new technique for computing the FSC values that is called virtually calibrated projection moire interferometry (VCPMI). VCPMI is based on computer simulations of the conventional PMI process and does not require moving the actual test object or reference plane. We validate the VCPMI approach by comparing results for a flat plate and an airfoil with those made by use of other measurement methods. PMID:15881060

  20. Meson interferometry in relativistic heavy ion collisions

    SciTech Connect

    Not Available

    1993-05-01

    This report contains discussions on the following topics: Recent HBT results form CERN experiment NA44; interferometry results from E802/E859/E866; recent results on two particle correlations from E814; source sizes from CERN data; intermittency and interferometry; Bose-Einstein correlations in 200A GeV S+Au collisions; HBT correlations at STAR; HBT interferometry with PHENIX; HBT calculations from ARC; three pion correlations; and pion correlations in proton-induced reactions.

  1. Geometric Landau-Zener interferometry.

    PubMed

    Gasparinetti, S; Solinas, P; Pekola, J P

    2011-11-11

    We propose a new type of interferometry, based on geometric phases accumulated by a periodically driven two-level system undergoing multiple Landau-Zener transitions. As a specific example, we study its implementation in a superconducting charge pump. We find that interference patterns appear as a function of the pumping frequency and the phase bias, and clearly manifest themselves in the pumped charge. We also show that the effects described should persist in the presence of realistic decoherence. PMID:22181761

  2. Acoustic neuroma

    MedlinePlus

    Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor ... 177. Battista RA. Gamma knife radiosurgery for vestibular schwannoma. Otolaryngol Clin North Am . 2009;42:635-654. ...

  3. Quasi-Heterodyne Hologram Interferometry

    NASA Astrophysics Data System (ADS)

    Hariharan, P.

    1985-08-01

    Wider use of hologram interferometry for quantitative measure-ments has been delayed by the fact that interpolation between the fringe maxima and minima to obtain the optical path difference at a particular point in the field is laborious and inaccurate. A solution to this problem is quasi-hetero-dyne interferometry, which permits rapid and accurate measurements simultaneously at a number of points distributed over the interference pattern. In this technique a television camera is used in conjunction with digital electronics to measure and store the irradiance values at points on a rectangular sampling grid covering the real-time interference fringes. The phase difference between the interfering wavefronts at each point is then calculated from the irradiance values obtained from successive scans of the camera made while the phase of one of the wavefronts is shifted either continuously or in steps. A practical system is described with which values of the optical path difference for 10,000 data points can be obtained with an accuracy of +/- A/200 in less than 10 s. The application of quasi-heterodyne hologram interferometry to the measurement of vector displacements and to holographic contouring is discussed.

  4. Stitching interferometry: side effects and PSD

    NASA Astrophysics Data System (ADS)

    Bray, Michael

    1999-11-01

    Stitching Interferometry is rapidly emerging as an alternative to Standard Interferometry, in the measurement of Large Optics -- such as those found in Laser MegaJoule and NIF. Stitching Interferometry involves multiple overlapping sub-aperture measurements over large components, and a computer software to reconstruct the wavefronts. Obviously, the Stitching Interferometer's measurement characteristics have to be different to those of the Standard Interferometer of same nominal measurement area. Two questions emerge: (1) What metric do we choose to express these characteristics? (2) How does Stitching Interferometry compare to Standard Interferometry, using this metric? We choose to use the PSD to illustrate how Stitching Interferometry of large components compares with Standard Large-Size Interferometry, for various lateral scales. Also, we highlight some important characteristics of Stitching Interferometry, which arise from judicious use of the particular configuration of the device. Ignorance of basic propagation phenomena can lead to bad design of the Stitching Interferometer, and loss of any performance advantage over Standard Interferometry. Because many of these effects are not direct consequences of the Stitching process, we call them side effects. In this paper, we provide basic explanation, and keep the mathematics to a low profile -- indeed, it is not necessary to actually compute anything to understand the effects. However, some very basic formulas, a few numerical tables and lots of graphs are presented, in order to provide basis for discussion.

  5. Musical Acoustics

    NASA Astrophysics Data System (ADS)

    Gough, Colin

    This chapter provides an introduction to the physical and psycho-acoustic principles underlying the production and perception of the sounds of musical instruments. The first section introduces generic aspects of musical acoustics and the perception of musical sounds, followed by separate sections on string, wind and percussion instruments.

  6. Interferometry with synthetic gauge fields

    SciTech Connect

    Anderson, Brandon M.; Taylor, Jacob M.; Galitski, Victor M.

    2011-03-15

    We propose a compact atom interferometry scheme for measuring weak, time-dependent accelerations. Our proposal uses an ensemble of dilute trapped bosons with two internal states that couple to a synthetic gauge field with opposite charges. The trapped gauge field couples spin to momentum to allow time-dependent accelerations to be continuously imparted on the internal states. We generalize this system to reduce noise and estimate the sensitivity of such a system to be S{approx}10{sup -7}(m/s{sup 2}/{radical}(Hz)).

  7. 50 years of holographic interferometry

    NASA Astrophysics Data System (ADS)

    Stetson, Karl A.

    2015-01-01

    Fifty years ago, Robert L. Powell and I discovered holographic interferometry while working at the Radar Laboratory of the University of Michigan's Institute of Science and Technology. I have worked in this field for this entire time span, watched it grow from an unexplored technology to become a widespread industrial testing method, and I have contributed to these developments. In this paper, I will trace my history in this field from our discovery to my involvement in its theory and applications. I will conclude with a discussion of digital holography, which is currently replacing photographic holography for most research and industrial applications.

  8. Vibration modulated subaperture stitching interferometry.

    PubMed

    Liang, Chao-Wen; Chang, Hung-Sheng; Lin, Po-Chih; Lee, Cheng-Chung; Chen, Yi-Chun

    2013-07-29

    A novel subaperture stitching interferometry is developed to measure the surface deformation of the lens by utilizing the mechanical vibration induced from a motorized stage. The interferograms of different subapertures are acquired on the fly while the tested optics is rotating against its symmetrical axis. The measurement throughput and the subaperture positioning accuracy are improved simultaneously by adopting both the synchronous rotational scanning mechanism and the non-uniform phase shifting algorithm. The experimental measurement shows the stitched phase RMS error of 0.0037 waves proving the feasibility of the proposed phase acquisition method. PMID:23938696

  9. Virtual Reference Interferometry: Theory & Experiment

    NASA Astrophysics Data System (ADS)

    Galle, Michael Anthony

    This thesis introduces the idea that a simulated interferogram can be used as a reference for an interferometer. This new concept represents a paradigm shift from the conventional thinking, where a reference is the phase of a wavefront that traverses a known path. The simulated interferogram used as a reference is called a virtual reference. This thesis develops the theory of virtual reference interferometry and uses it for the characterization of chromatic dispersion in short length (<1m) fibers and optical components. Characterization of chromatic dispersion on short length fiber and optical components is a very difficult challenge. Accurate measurement of first and second order dispersion is important for applications from optical component design to nonlinear photonics, sensing and communications. Techniques for short-length dispersion characterization are therefore critical to the development of many photonic systems. The current generation of short-length dispersion measurement techniques are either easy to operate but lack sufficient accuracy, or have sufficient accuracy but are difficult to operate. The use of a virtual reference combines the advantages of these techniques so that it is both accurate and easy to operate. Chromatic dispersion measurements based on virtual reference interferometry have similar accuracy as the best conventional measurement techniques due to the ability to measure first and second order dispersion directly from the interference pattern. Unique capabilities of virtual reference interferometry are demonstrated, followed by a derivation of the operational constraints and system parameters. The technique is also applied to the characterization of few-mode fibers, a hot topic in telecommunications research where mode division multiplexing promises to expand network bandwidth. Also introduced is the theory of dispersive virtual reference interferometry, which can be used to overcome the bandwidth limitations associated with the

  10. An Interferometry Imaging Beauty Contest

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  11. Golographic interferometry of physical processes

    NASA Astrophysics Data System (ADS)

    Ostrovskaya, G. V.

    2016-06-01

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

  12. Two-frequency Ramsey interferometry

    SciTech Connect

    Seidel, D.; Muga, J. G.

    2007-02-15

    We investigate Ramsey interferometry for two separated fields oscillating with different frequencies. It is shown that the interplay between average and relative detuning leads to interference effects not present in the standard, single-frequency setup. For a large free-flight time of ground-state atoms before entering the first field region, the Ramsey fringes with respect to the relative detuning become much narrower than the usual ones. The stability of these effects with respect to phase or velocity fluctuations is discussed.

  13. Room Acoustics

    NASA Astrophysics Data System (ADS)

    Kuttruff, Heinrich; Mommertz, Eckard

    The traditional task of room acoustics is to create or formulate conditions which ensure the best possible propagation of sound in a room from a sound source to a listener. Thus, objects of room acoustics are in particular assembly halls of all kinds, such as auditoria and lecture halls, conference rooms, theaters, concert halls or churches. Already at this point, it has to be pointed out that these conditions essentially depend on the question if speech or music should be transmitted; in the first case, the criterion for transmission quality is good speech intelligibility, in the other case, however, the success of room-acoustical efforts depends on other factors that cannot be quantified that easily, not least it also depends on the hearing habits of the listeners. In any case, absolutely "good acoustics" of a room do not exist.

  14. Acoustic Neuroma

    MedlinePlus

    ... slow growing tumor which arise primarily from the vestibular portion of the VIII cranial nerve and lie ... you have a "brain tumor" called acoustic neuroma (vestibular schwannoma). You think you are the only one ...

  15. Underwater Acoustics

    NASA Astrophysics Data System (ADS)

    Kuperman, William A.; Roux, Philippe

    It is well underwater established that sound waves, compared to electromagnetic waves, propagate long distances in the ocean. Hence, in the ocean as opposed to air or a vacuum, one uses sound navigation and ranging (SONAR) instead navigation and ranging (SONAR) of radar, acoustic communication instead of radio, and acoustic imaging and tomography instead of microwave or optical imaging or X-ray tomography. Underwater acoustics is the science of sound in water (most commonly in the ocean) and encompasses not only the study of sound propagation, but also the masking of sound signals by interfering phenomenon and signal processing for extracting these signals from interference. This chapter we will present the basics physics of ocean acoustics and then discuss applications.

  16. Measuring Speeds with Microwave Interferometry

    NASA Astrophysics Data System (ADS)

    Hillberry, Logan

    2014-03-01

    The speed of an approximately frictionless cart is simultaneously measured in two ways. A 10.5 GHz microwave source is used in the familiar Michelson interferometry setup with one of the arms being the mobile cart and the other being a stationary microwave receiver. As the cart travels, the changing interference pattern is captured on an oscilloscope which, when combined with the source frequency, can be used to determine the cart's speed. The second speed measurement is achieved by sending a laser beam across the cart's path into a photo detector which is connected a second channel on the oscilloscope. The cart breaks the beam and travels a distance equal to its length before allowing the beam to reach the photo detector again. Using the oscilloscope's timing measurement and the known cart length, one can readily calculate the cart's speed. Comparison of the two methods conveys agreement within error, confirming the path length difference model used to calculate the speed of the cart in the microwave interferometry method.

  17. Bibliography of spatial interferometry in optical astronomy

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  18. Bibliography of spatial interferometry in optical astronomy

    NASA Astrophysics Data System (ADS)

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

    1990-02-01

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

  19. Acoustic biosensors

    PubMed Central

    Fogel, Ronen; Seshia, Ashwin A.

    2016-01-01

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. PMID:27365040

  20. Acoustic biosensors.

    PubMed

    Fogel, Ronen; Limson, Janice; Seshia, Ashwin A

    2016-06-30

    Resonant and acoustic wave devices have been researched for several decades for application in the gravimetric sensing of a variety of biological and chemical analytes. These devices operate by coupling the measurand (e.g. analyte adsorption) as a modulation in the physical properties of the acoustic wave (e.g. resonant frequency, acoustic velocity, dissipation) that can then be correlated with the amount of adsorbed analyte. These devices can also be miniaturized with advantages in terms of cost, size and scalability, as well as potential additional features including integration with microfluidics and electronics, scaled sensitivities associated with smaller dimensions and higher operational frequencies, the ability to multiplex detection across arrays of hundreds of devices embedded in a single chip, increased throughput and the ability to interrogate a wider range of modes including within the same device. Additionally, device fabrication is often compatible with semiconductor volume batch manufacturing techniques enabling cost scalability and a high degree of precision and reproducibility in the manufacturing process. Integration with microfluidics handling also enables suitable sample pre-processing/separation/purification/amplification steps that could improve selectivity and the overall signal-to-noise ratio. Three device types are reviewed here: (i) bulk acoustic wave sensors, (ii) surface acoustic wave sensors, and (iii) micro/nano-electromechanical system (MEMS/NEMS) sensors. PMID:27365040

  1. Software tools for optical interferometry

    NASA Astrophysics Data System (ADS)

    Thureau, Nathalie D.; Ireland, Michael; Monnier, John D.; Pedretti, Ettore

    2006-06-01

    We describe a set of general purpose utilities for visualizing and manipulating optical interferometry data stored in the FITS-based OIFITS data format. This class of routines contains code like the OiPlot navigation/visualization tool which allows the user to extract visibility, closure phase and UV-coverage information from the OIFITS files and to display the information in various ways. OiPlot also has basic data model fitting capabilities which can be used for a rapid first analysis of the scientific data. More advanced image reconstruction techniques are part of a dedicated utility. In addition, these routines allow data from multiple interferometers to be combined and used together. Part of our work also aims at developing software specific to the Michigan InfraRed Combiner (MIRC). Our experience designing a flexible and robust graphical user interfaced based on sockets using python libraries has wide applicability and this paper will discuss practicalities.

  2. Synthetic aperture interferometry: error analysis

    SciTech Connect

    Biswas, Amiya; Coupland, Jeremy

    2010-07-10

    Synthetic aperture interferometry (SAI) is a novel way of testing aspherics and has a potential for in-process measurement of aspherics [Appl. Opt.42, 701 (2003)].APOPAI0003-693510.1364/AO.42.000701 A method to measure steep aspherics using the SAI technique has been previously reported [Appl. Opt.47, 1705 (2008)].APOPAI0003-693510.1364/AO.47.001705 Here we investigate the computation of surface form using the SAI technique in different configurations and discuss the computational errors. A two-pass measurement strategy is proposed to reduce the computational errors, and a detailed investigation is carried out to determine the effect of alignment errors on the measurement process.

  3. Some applications of holographic interferometry in biomechanics

    NASA Astrophysics Data System (ADS)

    Ebbeni, Jean P. L.

    1992-03-01

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

  4. Two-center interferometry and decoherence effects

    SciTech Connect

    Feagin, James M.

    2006-02-15

    We analyze reduced fringe visibilities and decoherence effects in two-center interference experiments involving photon scattering and trapped-ion and atom interferometry. We introduce an impulse approximation to analyze the resulting photon-atom momentum entanglement. We find that the simple decoherence due to photon scattering of double-humped center-of-mass states of a single trapped ion strongly resembles that observed in atom interferometry.

  5. Results of Infrasound Interferometry in Netherlands

    NASA Astrophysics Data System (ADS)

    Fricke, J. T.; Ruigrok, E. N.; Evers, L. G.; Simons, D. G.; Wapenaar, K.

    2012-04-01

    with an aperture of around 100 km. The in-house developed microbarometers are able to measure infrasound up to a period of 1000 seconds, which is in the acoustic-gravity wave regime. The results will also be directly applicable to the verification of the 'Comprehensive Nuclear-Test-Ban Treaty' (CTBT), where uncertainties in the atmospheric propagation of infrasound play a dominant role. This research is made possible by the support of the 'Netherlands Organisation for Scientific Research' (NWO). Haney, M., 2009. Infrasonic ambient noise interferometry from correlations of microbaroms, Geophysical Research Letters, 36, L19808, doi:10.1029/2009GL040179

  6. Visualisation and analysis of three dimensional transonic flows by holographic interferometry

    NASA Astrophysics Data System (ADS)

    Towers, D. P.; Towers, C. E.; Bryanston-Cross, P. J.; Fry, K.; Harris, A. E.

    1992-01-01

    Holographic interferometry has been used in a large scale transonic wind tunnel to produce a 3D flow visualization. The experiments have been carried out on a model civil transport aircraft wing and turbine powered engine simulator combination. This study is significant industrially as the method forms a diagnostic for turbofan installations. The holograms show many relevant flow features including shock waves, flow interactions between the engine simulator flow and the freestream flow, secondary flows, and acoustic waves. Quantitative 3D position information has also been obtained for some of these features. A comparison to other flow diagnostic methods has been made in this paper.

  7. Acoustic transducer for acoustic microscopy

    DOEpatents

    Khuri-Yakub, Butrus T.; Chou, Ching H.

    1990-01-01

    A shear acoustic transducer-lens system in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens.

  8. Acoustic transducer for acoustic microscopy

    DOEpatents

    Khuri-Yakub, B.T.; Chou, C.H.

    1990-03-20

    A shear acoustic transducer-lens system is described in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens. 9 figs.

  9. Precision optical interferometry in space

    NASA Technical Reports Server (NTRS)

    Reasenberg, Robert D.

    1993-01-01

    POINTS, an astrometric Optical interferometer with a nominal measurement accuracy of 5 microarcseconds for the angle between a pair of stars separated by about 90 deg, is presently under consideration by two divisions of NASA-OSSA. It will be a powerful new multi-disciplinary tool for astronomical research. If chosen as the TOPS-1 (Toward Other Planetary Systems) instrument by the Solar-System Exploration Division, it will perform a definitive search for extra-solar planetary systems, either finding and characterizing a large number of them or showing that they are far less numerous than now believed. If chosen as the AIM (Astrometric Interferometry Mission) by the Astrophysics Division, POINTS will open new areas of astrophysical research and change the nature of the questions being asked in some old areas. In either case. it will be the first of a new class of powerful instruments in space and will prove the technology for the larger members of that class to follow. Based on a preliminary indication of the observational needs of the two missions, we find that a single POINTS mission will meet the science objectives of both TOPS-1 and AIM. The instrument detects dispersed fringe (channel led spectrum) and therefore can tolerate large pointing errors.

  10. Structural influences on intensity interferometry

    NASA Astrophysics Data System (ADS)

    Maji, Arup; Harris, Mark

    2016-01-01

    Intensity interferometry (II) is an alternate form of creating images of distant objects. It is significantly less sensitive to atmospheric distortions and aberrations of telescope surfaces than conventional amplitude-based imaging. The deficiencies of II can be overcome as photodetectors' read-out rates are becoming faster and computers more powerful. In recognition of the possibility of very large space-based imaging systems, this paper investigates how the deformation of a large, thin optical surface would influence the accuracy of II. Based on the theoretical foundation of II, an optical ray-tracing algorithm was used to examine how the statistics of a photon stream changes from the source to the detector. Ray-tracing and finite element analyses of the structure were thereafter integrated to quantify how the correlation of the intensity field changes as the reflective structure deforms. Varying the positions of the detector from the focal plane and the surface profile of the mirror provided an understanding and quantification of how the various scenarios affect the statistics of the detected light and the correlation measurement. This research and analysis provide the means to quantify how structural perturbations of focal mirrors affect the statistics of photon stream detections inherent in II instrumentation.

  11. Stitching interferometry of aspherical surfaces

    NASA Astrophysics Data System (ADS)

    Haensel, Thomas; Nickel, Andreas; Schindler, Axel

    2001-12-01

    Sub-aperture stitching interferometry (SASI) is an appropriate method to measure either large optical plane surface topologies or aspheres with strong deviation from the flatness with standard interferometers. Using SASI the surface shape is measured with a higher lateral resolution by multiple adjacent sub-aperture measurements with a sufficient overlap of the neighboring areas. In a second step, the total surface shape is composed with the help of a computer code by stitching the sub-aperture areas together. The overlap areas allow fitting. By means of a regression analysis, tilt and vertical displacement of adjacent areas are calculated and minimized. A confidence band calculated using a MATLAB based code describes the accuracy of the composition. The variance of this estimation is inverse proportional to the peak to valley value (PV) of the measured area and decreases with a 10-3 scaling of the width of the overlapping area. A statistical experimental design method is used to minimize the number of sub-apertures to be measured. The accuracy of the stitched total surface measurement can be increased with the help of model calculations by optimizing (i) the position of the sub-aperture, which was regarded as a standard, and (ii) the sequence of the stitched adjacent areas.

  12. Neutron interferometry with cold stage

    NASA Astrophysics Data System (ADS)

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

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

  13. KERNEL PHASE IN FIZEAU INTERFEROMETRY

    SciTech Connect

    Martinache, Frantz

    2010-11-20

    The detection of high contrast companions at small angular separation appears feasible in conventional direct images using the self-calibration properties of interferometric observable quantities. The friendly notion of closure phase, which is key to the recent observational successes of non-redundant aperture masking interferometry used with adaptive optics, appears to be one example of a wide family of observable quantities that are not contaminated by phase noise. In the high-Strehl regime, soon to be available thanks to the coming generation of extreme adaptive optics systems on ground-based telescopes, and already available from space, closure phase like information can be extracted from any direct image, even taken with a redundant aperture. These new phase-noise immune observable quantities, called kernel phases, are determined a priori from the knowledge of the geometry of the pupil only. Re-analysis of archive data acquired with the Hubble Space Telescope NICMOS instrument using this new kernel-phase algorithm demonstrates the power of the method as it clearly detects and locates with milliarcsecond precision a known companion to a star at angular separation less than the diffraction limit.

  14. ARISE - Advanced Radio Interferometry Between Space and Earth

    NASA Technical Reports Server (NTRS)

    Ulvestad, J. S.; Linfield, R. P.; Wannier, P. G.; Preston, R. A.; Hirabayashi, H.; Zensus, J. A.; Veal, G. R.

    1995-01-01

    A mission is described called ARISE, Advanced Radio Interferometry between Space and Earth. ARISE will will provide affordable very long baseline interferometry (VLBI) using second- generation VLBI and one or more inflatable space radio telescopes.

  15. Persistent Scatterer Interferometry Using SENTINEL-1 Data

    NASA Astrophysics Data System (ADS)

    Crosetto, M.; Monserrat, O.; Devanthéry, N.; Cuevas-González, M.; Barra, A.; Crippa, B.

    2016-06-01

    This paper is focused on deformation monitoring using a Persistent Scatterer Interferometry technique and the interferometric SAR data acquired by the Sentinel-1 satellite of the European Space Agency. The first part of the paper describes the procedure used to process and analyze Sentinel-1 interferometric SAR data. Two main approaches are described. The first one is a simplified Persistent Scatterer Interferometry approach that exploits two key properties of the Sentinel-1 data: the high coherence of the 12-day interferograms and the reduced orbital tube. The second approach is a full Persistent Scatterer Interferometry approach, where a more sophisticate data treatment is employed. The second part of the paper illustrates the results obtained with the two processing approaches. Two case studies are described. The first one concerns landslide detection and monitoring. In this case, the simplified Persistent Scatterer Interferometry approach was used. The second one regards the deformation monitoring of an urban area. In this case, a full Persistent Scatterer Interferometry approach was used.

  16. Medical Acoustics

    NASA Astrophysics Data System (ADS)

    Beach, Kirk; Dunmire, Barbrina

    Medical acoustics can be subdivided into diagnostics and therapy. Diagnostics are further separated into auditory and ultrasonic methods, and both employ low amplitudes. Therapy (excluding medical advice) uses ultrasound for heating, cooking, permeablizing, activating and fracturing tissues and structures within the body, usually at much higher amplitudes than in diagnostics. Because ultrasound is a wave, linear wave physics are generally applicable, but recently nonlinear effects have become more important, even in low-intensity diagnostic applications.

  17. Acoustic chaos

    SciTech Connect

    Lauterborn, W.; Parlitz, U.; Holzfuss, J.; Billo, A.; Akhatov, I.

    1996-06-01

    Acoustic cavitation, a complex, spatio-temporal dynamical system, is investigated with respect to its chaotic properties. The sound output, the {open_quote}{open_quote}noise{close_quote}{close_quote}, is subjected to time series analysis. The spatial dynamics of the bubble filaments is captured by high speed holographic cinematography and subsequent digital picture processing from the holograms. Theoretical models are put forward for describing the pattern formation. {copyright} {ital 1996 American Institute of Physics.}

  18. Active and passive interferometry with a deep-water OBS array

    NASA Astrophysics Data System (ADS)

    Carrière, O.; Gerstoft, P.

    2012-12-01

    Green's function estimation between two points from ambient noise relies on the assumption of diffuse noise field. Directional noise field from ships or other anthropogenic activity may bias the travel time estimates. In April 2011, fifteen ocean bottom seismometers (OBS) were deployed on a straight line in the Gulf of Mexico at 900-m water depth. During the next few days, both ambient noise data and active surveys using air-gun were recorded. This work compares the reflectivity estimates obtained from controlled source (active) interferometry and ambient noise (passive) crosscorrelation of hydrophone and geophone signals. Compared to conventional seismic processing, active interferometry suppresses the need of survey source position knowledge and removes statics. Passive interferometry removes the need of active surveys but typically requires longer term deployment. The noise sequence collected in the Gulf of Mexico is dominated by a distant seismic exploration from a single direction. The impact of such strong and highly directional and acoustic source on the Green's function extraction is discussed and compared to simulated diffuse noise field crosscorrelation. The utility of beamforming technique and eigenvector subspace projection for attenuating the directional noise is examined in details.

  19. Optical intensity interferometry through atmospheric turbulence

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  20. Soft x-ray interferometry

    SciTech Connect

    Not Available

    1993-09-01

    The purpose of the soft x-ray interferometry workshop held at Lawrence Berkeley Laboratory was to discuss with the scientific community the proposed technical design of the soft x-ray Fourier-transform spectrometer being developed at the ALS. Different design strategies for the instrument`s components were discussed, as well as detection methods, signal processing issues, and how to meet the manufacturing tolerances that are necessary for the instrument to achieve the desired levels of performance. Workshop participants were encouraged to report on their experiences in the field of Fourier transform spectroscopy. The ALS is developing a Fourier transform spectrometer that is intended to operate up to 100 eV. The motivation is solely improved resolution and not the throughput (Jaquinot) or multiplex (Fellgett) advantage, neither of which apply for the sources and detectors used in this spectral range. The proposed implementation of this is via a Mach-Zehnder geometry that has been (1) distorted from a square to a rhombus to get grazing incidence of a suitable angle for 100 eV and (2) provided with a mirror-motion system to make the path difference between the interfering beams tunable. The experiment consists of measuring the emergent light intensity (I(x)) as a function of the path difference (x). The resolving power of the system is limited by the amount of path difference obtainable that is 1 cm (one million half-waves at 200{angstrom} wavelength) in the design thus allowing a resolving power of one million. The free spectral range of the system is limited by the closeness with which the function I(x) is sampled. It is proposed to illuminate a helium absorption cell with roughly 1%-band-width light from a monochromator thus allowing one hundred aliases without spectral overlap even for sampling of I(x) at one hundredth of the Nyquist frequency.

  1. Parasitic interference in nulling interferometry

    NASA Astrophysics Data System (ADS)

    Matter, A.; Defrère, D.; Danchi, W. C.; Lopez, B.; Absil, O.

    2013-05-01

    Nulling interferometry aims to detect faint objects close to bright stars. Its principle is to produce a destructive interference along the line of sight so that the stellar flux is rejected, while the flux of the off-axis source can be transmitted. In practice, various instrumental perturbations can degrade the nulling performance. Any imperfection in phase, amplitude or polarization produces a spurious flux that leaks to the interferometer output and corrupts the transmitted off-axis flux. One of these instrumental perturbations is the crosstalk phenomenon, which occurs because of multiple parasitic reflections inside transmitting optics, and/or diffraction effects related to beam propagation along finite size optics. It can include a crosstalk of a beam with itself, and a mutual crosstalk between different beams. This can create a parasitic interference pattern, which degrades the intrinsic transmission map - or intensity response - of the interferometer. In this context, we describe how this instrumental effect impairs the performance of a Bracewell interferometer. A simple formalism is developed to derive the corresponding modified intensity response of the interferometer, as a function of the two parameters of interest: the crosstalk level (or contamination rate) and the phase shift between the primary and secondary - parasitic - beams. We then apply our mathematical approach to a few scientific cases, both analytically and using the GENIESIM simulation software, adapted to handle coherent crosstalk. Our results show that a coherent crosstalk level of about 1 per cent implies a 20 per cent drop of the signal-to-noise ratio at most. Careful attention should thus be paid to reduce the crosstalk level inside an interferometric instrument and ensure an instrumental stability that provides the necessary sensitivity through calibration procedures.

  2. Advances in Small-Telescope Speckle Interferometry

    NASA Astrophysics Data System (ADS)

    Rowe, David J.

    2016-06-01

    The current revolution in CMOS camera technology has enabled a new generation of small telescope systems targeted at the measurement of close binary systems using the techniques of speckle interferometry and bispectrum analysis. These inexpensive, ultra-sensitive, high resolution cameras are now outperforming CCD technology, and come at a truly affordable price. In addition, dedicated, user-friendly speckle interferometry reduction software has been developed for the amateur, making it easy to perform the otherwise complicated data processing tasks. This talk will address these recent advances in hardware and software, and describe some of the results of the informal amateur-professional collaboration that has formed around them.

  3. Dispersed interferometry for infrared exoplanet velocimetry

    NASA Astrophysics Data System (ADS)

    Edelstein, Jerry; Muterspaugh, Matthew W.; Erskine, David; Marckwordt, Mario; Feuerstein, W. Michael; Mercer, Tony; Czeszumska, Agnieszka; Schwer, Jaclyn; Halverson, Sam; Lloyd, James P.; Muirhead, Philip S.; Wright, Jason T.; Herter, Terry

    2008-07-01

    The TEDI (TripleSpec - Exoplanet Discovery Instrument) is the first instrument dedicated to the near infrared radial velocity search for planetary companions to low-mass stars. The TEDI uses Externally Dispersed Interferometry (EDI), a combination of interferometry and multichannel dispersive spectroscopy. We have joined a white-light interferometer with the Cornell TripleSpec (0.9 - 2.4 μm) spectrograph at the Palomar Observatory 200" telescope and begun an experimental program to establish both the experimental and analytical techniques required for precision IR velocimetry and the Doppler-search for planets orbiting low mass stars and brown dwarfs.

  4. Spectral modulation interferometry for quantitative phase imaging

    PubMed Central

    Shang, Ruibo; Chen, Shichao; Li, Chengshuai; Zhu, Yizheng

    2015-01-01

    We propose a spectral-domain interferometric technique, termed spectral modulation interferometry (SMI), and present its application to high-sensitivity, high-speed, and speckle-free quantitative phase imaging. In SMI, one-dimensional complex field of an object is interferometrically modulated onto a broadband spectrum. Full-field phase and intensity images are obtained by scanning along the orthogonal direction. SMI integrates the high sensitivity of spectral-domain interferometry with the high speed of spectral modulation to quantify fast phase dynamics, and its dispersive and confocal nature eliminates laser speckles. The principle and implementation of SMI are discussed. Its performance is evaluated using static and dynamic objects. PMID:25780737

  5. Altimetry Using GPS-Reflection/Occultation Interferometry

    NASA Technical Reports Server (NTRS)

    Cardellach, Estel; DeLaTorre, Manuel; Hajj, George A.; Ao, Chi

    2008-01-01

    A Global Positioning System (GPS)- reflection/occultation interferometry was examined as a means of altimetry of water and ice surfaces in polar regions. In GPS-reflection/occultation interferometry, a GPS receiver aboard a satellite in a low orbit around the Earth is used to determine the temporally varying carrier- phase delay between (1) one component of a signal from a GPS transmitter propagating directly through the atmosphere just as the GPS transmitter falls below the horizon and (2) another component of the same signal, propagating along a slightly different path, reflected at glancing incidence upon the water or ice surface.

  6. Holographic interferometry: A user`s guide

    SciTech Connect

    Griggs, D.

    1993-10-01

    This manual describes the procedures and components necessary to produce a holographic interferogram of a flow field in the Sandia National Laboratories hypersonic wind tunnel. In contrast to classical interferometry, holographic interferometry records the amplitude and phase distribution of a lightwave passing through the flow field at some instant of time. This information can then be reconstructed outside the wind tunnel for visual analysis and digital processing, yielding precise characterizations of aerodynamic phenomena. The reconstruction and subsequent hologram image storage process is discussed, with particular attention paid to the digital image processor and the data reduction technique.

  7. Shear-strain contours from moire interferometry

    NASA Technical Reports Server (NTRS)

    Post, D.; Czarnek, R.; Joh, D.

    1985-01-01

    The development of whole-field contour maps of shear strains gamma (xy), derived from displacement fields obtained by moire interferometry with 2400 lines/mm, is described. The use of mechanical differentiation to obtain cross-derivatives of displacements and the use of graphical additive moire to sum the cross-derivatives are explained. Quantitative analysis in the small-strain domain is possible because of the high sensitivity of moire interferometry. The applicability of this technique is shown by the testing of a short epoxy beam under three-point bending.

  8. Ocean acoustic remote sensing using ambient noise: results from the Florida Straits

    NASA Astrophysics Data System (ADS)

    Brown, M. G.; Godin, O. A.; Zang, X.; Ball, J. S.; Zabotin, N. A.; Zabotina, L. Y.; Williams, N. J.

    2016-07-01

    Noise interferometry is the process by which approximations to acoustic Green's functions, which describe sound propagation between two locations, are estimated by cross-correlating time series of ambient noise measured at those locations. Noise-interferometry-based approximations to Green's functions can be used as the basis for a variety of inversion algorithms, thereby providing a purely passive alternative to active-source ocean acoustic remote sensing. In this paper we give an overview of results from noise interferometry experiments conducted in the Florida Straits at 100 m depth in December 2012, and at 600 m depth in September/October 2013. Under good conditions for noise interferometry, estimates of cross-correlation functions are shown to allow one to perform advanced phase-coherent signal processing techniques to perform waveform inversions, estimate currents by exploiting non-reciprocity, perform time-reversal/back-propagation calculations and investigate modal dispersion using time-warping techniques. Conditions which are favourable for noise interferometry are identified and discussed.

  9. Acoustic Tooth Cleaner

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.

    1984-01-01

    Acoustically-energized water jet aids in plaque breakdown. Acoustic Wand includes acoustic transducer 1/4 wave plate, and tapered cone. Together elements energize solution of water containing mild abrasive injected into mouth to help prevent calculous buildup.

  10. Subsonic jet pressure fluctuation characterization by tomographic laser interferometry

    NASA Astrophysics Data System (ADS)

    Martarelli, Milena; Castellini, Paolo; Tomasini, Enrico Primo

    2013-12-01

    This paper describes the application of a nonconventional experimental technique based on optical interferometry for the characterization of aeroacoustic sources. The specific test case studied is a turbulent subsonic jet. Traditional experimental methods exploited for the measurement of aerodynamic velocity fields are laser Doppler anemometer and particle image velocimetry which have an important drawback due to the fact that they can measure only if the flow is seeded with tracer particles. The technique proposed, by exploiting a laser Doppler interferometer and a tomographic algorithm for 3D field reconstruction, overcomes the problem of the flow seeding since it allows directly measuring the flow pressure fluctuation due to the flow turbulence. A laser Doppler interferometer indeed is sensitive to the density oscillation within the medium traversed by the laser beam even though it integrates the density oscillation along the entire path traveled by the laser. Consequently, the 3D distribution of the flow density fluctuation can be recovered only by exploiting a tomographic reconstruction algorithm applied to several projections. Finally, the flow pressure fluctuation can be inferred from the flow density measured, which comprehends both the aerodynamic pressure related to the turbulence and the sound pressure due to the propagation of the acoustic waves into the far field. In relation to the test case studied in this paper, e.g., the turbulent subsonic jet, the method allows a complete aeroacoustic characterization of the flow field since it measures both the aerodynamic "cause" of the noise, such as the vortex shedding, and the acoustic "effect" of it, i.e., the sound propagation in the 3D space. The performances and the uncertainty have been evaluated and discussed, and the technique has been experimentally validated.

  11. Acoustic transducer

    DOEpatents

    Drumheller, D.S.

    1997-12-30

    An acoustic transducer is described comprising a one-piece hollow mandrel into the outer surface of which is formed a recess with sides perpendicular to the central axis of the mandrel and separated by a first distance and with a bottom parallel to the central axis and within which recess are a plurality of washer-shaped discs of a piezoelectric material and at least one disc of a temperature-compensating material with the discs being captured between the sides of the recess in a pre-stressed interference fit, typically at 2,000 psi of compressive stress. The transducer also includes a power supply and means to connect to a measurement device. The transducer is intended to be used for telemetry between a measurement device located downhole in an oil or gas well and the surface. The transducer is of an construction that is stronger with fewer joints that could leak fluids into the recess holding the piezoelectric elements than is found in previous acoustic transducers. 4 figs.

  12. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S.

    1997-01-01

    An acoustic transducer comprising a one-piece hollow mandrel into the outer surface of which is formed a recess with sides perpendicular to the central axis of the mandrel and separated by a first distance and with a bottom parallel to the central axis and within which recess are a plurality of washer-shaped discs of a piezoelectric material and at least one disc of a temperature-compensating material with the discs being captured between the sides of the recess in a pre-stressed interference fit, typically at 2000 psi of compressive stress. The transducer also includes a power supply and means to connect to a measurement device. The transducer is intended to be used for telemetry between a measurement device located downhole in an oil or gas well and the surface. The transducer is of an construction that is stronger with fewer joints that could leak fluids into the recess holding the piezoelectric elements than is found in previous acoustic transducers.

  13. Detection of deoxynivalenol using biolayer interferometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biolayer interferometry allows for the real time monitoring of the interactions between molecules without the need for reagents with enzymatic, fluorescent, or radioactive labels. The technology is based upon the changes in interference pattern of light reflected from the surface of an optical fiber...

  14. Multiple Beam Interferometry in Elementary Teaching

    ERIC Educational Resources Information Center

    Tolansky, S.

    1970-01-01

    Discusses a relatively simple technique for demonstrating multiple beam interferometry. The technique can be applied to measuring (1) radii of curvature of lenses, (2) surface finish of glass, and (3) differential phase change on reflection. Microtopographies, modulated fringe systems and opaque objects may also be observed by this technique.…

  15. Phase-Shifted Laser Feedback Interferometry

    NASA Technical Reports Server (NTRS)

    Ovryn, Benjie

    1999-01-01

    Phase-shifted, laser feedback interferometry is a new diagnostic tool developed at the NASA Lewis Research Center under the Advanced Technology Development (ATD) Program directed by NASA Headquarters Microgravity Research Division. It combines the principles of phase-shifting interferometry (PSI) and laser-feedback interferometry (LFI) to produce an instrument that can quantify both optical path length changes and sample reflectivity variations. In a homogenous medium, the optical path length between two points is the product of the index of refraction and the geometric distance between the two points. LFI differs from other forms of interferometry by using the laser as both the source and the phase detector. In LFI, coherent feedback of the incident light either reflected directly from a surface or reflected after transmission through a region of interest will modulate the output intensity of the laser. The combination of PSI and LFI has produced a robust instrument, based on a low-power helium-neon (HeNe) gas laser, with a high dynamic range that can be used to measure either static or oscillatory changes of the optical path length. Small changes in optical path length are limited by the fraction of a fringe that can be measured; we can measure nonoscillatory changes with a root mean square (rms) error of the wavelength/1000 without averaging.

  16. Limitations To Optical/IR Interferometry

    NASA Technical Reports Server (NTRS)

    Colavita, M. M.

    1993-01-01

    The primary limitation to ground-based optical/IR interferometry is the turbulent atmosphere, which limits sensitivity by restricting the coherence volume, limits imaging accuracy by corrupting the fringe phase, and limits astrometric acuracy by corrupting the angel of arrival.

  17. Apparatus and method for laser velocity interferometry

    DOEpatents

    Stanton, Philip L.; Sweatt, William C.; Crump, Jr., O. B.; Bonzon, Lloyd L.

    1993-09-14

    An apparatus and method for laser velocity interferometry employing a fixed interferometer cavity and delay element. The invention permits rapid construction of interferometers that may be operated by those non-skilled in the art, that have high image quality with no drift or loss of contrast, and that have long-term stability even without shock isolation of the cavity.

  18. Radio interferometry: Techniques for Geodesy. [conference

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Progress in the development and application of radio interferometry as a tool for geophysical research is reported and discussed. Among the topics reviewed are: Surveys of is the Seventies, Movements, Terrestrial and Celestial, Degrees Kelvin and Degrees of Phase, the Mark 3 VLBI System, Waves of the Future and other Emissions, and Adherence and Coherence in Networks, and Plans.

  19. Space Interferometry System Testbed-3: architecture

    NASA Technical Reports Server (NTRS)

    Alvarez-Salazar, Oscar S.; Renaud, Goullioud; Azizi, Ali

    2004-01-01

    The Space Interferometry Mission's System testbed-3 has recently integrated its Precision Support Structure and spacecraft backpack on a pseudo free-free 0.5 Hz passive isolation system. The Precision Support Structure holds a 3-baseline stellar interferometer instrument.

  20. Measurements of the tympanic membrane with digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Muñoz Solís, S.; Mendoza Santoyo, F.; Del Socorro Hernández-Montes, M.

    2011-08-01

    In this paper a digital holographic interferometry (DHI) system with three object-illumination beams is used for the first time to detect and measure micrometer deformations on the surface of a tympanic membrane. Using this optical setup allows all three object displacement components x, y, and z, to be independently calculated. The corresponding deformations are registered using a cw laser in stroboscopic mode and a CCD camera synchronized to the excitation acoustic wave that produces a resonant vibration mode on the tympanic membrane surface. A series of digital holographic interferograms record the displacements undergone by the tympanic membrane and from them full field deformation phase maps are obtained. From the latter it is possible to observe the displacement of the tympanic membrane in response to the sound pressure. The study was performed on the tympanic membrane taken from a post-mortem cat. The results show the feasibility to apply a similar optomechanical arrangement for the study in humans, representing an alternative technique for the study of pathologies in the tympanic membrane.

  1. Acoustic cryocooler

    DOEpatents

    Swift, Gregory W.; Martin, Richard A.; Radenbaugh, Ray

    1990-01-01

    An acoustic cryocooler with no moving parts is formed from a thermoacoustic driver (TAD) driving a pulse tube refrigerator (PTR) through a standing wave tube. Thermoacoustic elements in the TAD are spaced apart a distance effective to accommodate the increased thermal penetration length arising from the relatively low TAD operating frequency in the range of 15-60 Hz. At these low operating frequencies, a long tube is required to support the standing wave. The tube may be coiled to reduce the overall length of the cryocooler. One or two PTR's are located on the standing wave tube adjacent antinodes in the standing wave to be driven by the standing wave pressure oscillations. It is predicted that a heat input of 1000 W at 1000 K will maintian a cooling load of 5 W at 80 K.

  2. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S.

    2000-01-01

    An active acoustic transducer tool for use down-hole applications. The tool includes a single cylindrical mandrel including a shoulder defining the boundary of a narrowed portion over which is placed a sandwich-style piezoelectric tranducer assembly. The piezoelectric transducer assembly is prestressed by being placed in a thermal interference fit between the shoulder of the mandrel and the base of an anvil which is likewise positioned over the narrower portion of the mandrel. In the preferred embodiment, assembly of the tool is accomplished using a hydraulic jack to stretch the mandrel prior to emplacement of the cylindrical sandwich-style piezoelectric transducer assembly and anvil. After those elements are positioned and secured, the stretched mandrel is allowed to return substantially to its original (pre-stretch) dimensions with the result that the piezoelectric transducer elements are compressed between the anvil and the shoulder of the mandrel.

  3. Acoustic hemostasis

    NASA Astrophysics Data System (ADS)

    Crum, L.; Andrew, M.; Bailey, M.; Beach, K.; Brayman, A.; Curra, F.; Kaczkowski, P.; Kargl, S.; Martin, R.; Vaezy, S.

    2003-04-01

    Over the past several years, the Center for Industrial and Medical Ultrasound (CIMU) at the Applied Physics Laboratory in the University of Washington has undertaken a broad research program in the general area of High Intensity Focused Ultrasound (HIFU). Our principal emphasis has been on the use of HIFU to induce hemostasis; in particular, CIMU has sought to develop a small, lightweight, portable device that would use ultrasound for both imaging and therapy. Such a technology is needed because nearly 50% of combat casualty mortality results from exsanguinations, or uncontrolled bleeding. A similar percentage occurs for civilian death due to trauma. In this general review, a presentation of the general problem will be given, as well as our recent approaches to the development of an image-guided, transcutaneous, acoustic hemostasis device. [Work supported in part by the USAMRMC, ONR and the NIH.

  4. Acoustic telemetry.

    SciTech Connect

    Drumheller, Douglas Schaeffer; Kuszmaul, Scott S.

    2003-08-01

    Broadcasting messages through the earth is a daunting task. Indeed, broadcasting a normal telephone conversion through the earth by wireless means is impossible with todays technology. Most of us don't care, but some do. Industries that drill into the earth need wireless communication to broadcast navigation parameters. This allows them to steer their drill bits. They also need information about the natural formation that they are drilling. Measurements of parameters such as pressure, temperature, and gamma radiation levels can tell them if they have found a valuable resource such as a geothermal reservoir or a stratum bearing natural gas. Wireless communication methods are available to the drilling industry. Information is broadcast via either pressure waves in the drilling fluid or electromagnetic waves in the earth and well tubing. Data transmission can only travel one way at rates around a few baud. Given that normal Internet telephone modems operate near 20,000 baud, these data rates are truly very slow. Moreover, communication is often interrupted or permanently blocked by drilling conditions or natural formation properties. Here we describe a tool that communicates with stress waves traveling through the steel drill pipe and production tubing in the well. It's based on an old idea called Acoustic Telemetry. But what we present here is more than an idea. This tool exists, it's drilled several wells, and it works. Currently, it's the first and only acoustic telemetry tool that can withstand the drilling environment. It broadcasts one way over a limited range at much faster rates than existing methods, but we also know how build a system that can communicate both up and down wells of indefinite length.

  5. All-optical probing of the nonlinear acoustics of a crack.

    PubMed

    Mezil, Sylvain; Chigarev, Nikolay; Tournat, Vincent; Gusev, Vitalyi

    2011-09-01

    Experiments with an all-optical method for the study of the nonlinear acoustics of cracks in solids are reported. Nonlinear acoustic waves are initiated by the absorption of radiation from a pair of laser beams intensity modulated at two different frequencies. The detection of acoustic waves at mixed frequencies, absent in the frequency spectrum of the heating lasers, by optical interferometry or deflectometry provides unambiguous evidence of the elastic nonlinearity of the crack. The high contrast in crack imaging achieved by remote optical monitoring of the nonlinear acoustic processes is due to the strong dependence of the efficiency of optoacoustic conversion on the state of the crack. The highest acoustic nonlinearity is observed in the transitional state of the crack, which is intermediate between the open and the closed ones. PMID:21886240

  6. Near-Earth Object Astrometric Interferometry

    NASA Technical Reports Server (NTRS)

    Werner, Martin R.

    2005-01-01

    Using astrometric interferometry on near-Earth objects (NEOs) poses many interesting and difficult challenges. Poor reflectance properties and potentially no significant active emissions lead to NEOs having intrinsically low visual magnitudes. Using worst case estimates for signal reflection properties leads to NEOs having visual magnitudes of 27 and higher. Today the most sensitive interferometers in operation have limiting magnitudes of 20 or less. The main reason for this limit is due to the atmosphere, where turbulence affects the light coming from the target, limiting the sensitivity of the interferometer. In this analysis, the interferometer designs assume no atmosphere, meaning they would be placed at a location somewhere in space. Interferometer configurations and operational uncertainties are looked at in order to parameterize the requirements necessary to achieve measurements of low visual magnitude NEOs. This analysis provides a preliminary estimate of what will be required in order to take high resolution measurements of these objects using interferometry techniques.

  7. Kinetic titration series with biolayer interferometry.

    PubMed

    Frenzel, Daniel; Willbold, Dieter

    2014-01-01

    Biolayer interferometry is a method to analyze protein interactions in real-time. In this study, we illustrate the usefulness to quantitatively analyze high affinity protein ligand interactions employing a kinetic titration series for characterizing the interactions between two pairs of interaction patterns, in particular immunoglobulin G and protein G B1 as well as scFv IC16 and amyloid beta (1-42). Kinetic titration series are commonly used in surface plasmon resonance and involve sequential injections of analyte over a desired concentration range on a single ligand coated sensor chip without waiting for complete dissociation between the injections. We show that applying this method to biolayer interferometry is straightforward and i) circumvents problems in data evaluation caused by unavoidable sensor differences, ii) saves resources and iii) increases throughput if screening a multitude of different analyte/ligand combinations. PMID:25229647

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

    SciTech Connect

    Abbott, Robert; Knox, Hunter Anne; James, Stephanie; Lee, Rebekah; Cole, Chris

    2016-01-01

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

  9. Atom interferometry in an optical cavity.

    PubMed

    Hamilton, Paul; Jaffe, Matt; Brown, Justin M; Maisenbacher, Lothar; Estey, Brian; Müller, Holger

    2015-03-13

    We propose and demonstrate a new scheme for atom interferometry, using light pulses inside an optical cavity as matter wave beam splitters. The cavity provides power enhancement, spatial filtering, and a precise beam geometry, enabling new techniques such as low power beam splitters (<100  μW), large momentum transfer beam splitters with modest power, or new self-aligned interferometer geometries utilizing the transverse modes of the optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with >75% contrast and measure the acceleration due to gravity, g, to 60  μg/sqrt[Hz] resolution in a Mach-Zehnder geometry. We use >10(7) cesium atoms in the compact mode volume (600  μm 1/e(2) waist) of the cavity and show trapping of atoms in higher transverse modes. This work paves the way toward compact, high sensitivity, multiaxis interferometry. PMID:25815912

  10. Externally Dispersed Interferometry for Planetary Studies

    SciTech Connect

    Erskine, D J; Edelstein, J; Harbeck, D; Lloyd, J

    2005-07-06

    We describe a plan to study the radial velocity of low mass stars and brown dwarfs using a combination of interferometry and multichannel dispersive spectroscopy, Externally Dispersed Interferometry (EDI). The EDI technology allows implementation of precision velocimetry and spectroscopy on existing moderate-resolution echelle or linear grating spectrograph over their full and simultaneous bandwidth. We intend to add EDI to the new Cornell TripleSpec infrared simultaneous JHK-band spectrograph at the Palomar Observatory 200'' telescope for a science-demonstration program that will allow a unique Doppler-search for planets orbiting low mass faint M, L and T type stars. The throughput advantage of EDI with a moderate resolution spectrograph is critical to achieving the requisite sensitivity for the low luminosity late L and T dwarfs.

  11. Nanoscale optical interferometry with incoherent light

    NASA Astrophysics Data System (ADS)

    Li, Dongfang; Feng, Jing; Pacifici, Domenico

    2016-02-01

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

  12. Nanoscale optical interferometry with incoherent light.

    PubMed

    Li, Dongfang; Feng, Jing; Pacifici, Domenico

    2016-01-01

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

  13. Station keeping strategy for multiple spacecraft interferometry

    NASA Technical Reports Server (NTRS)

    Decou, Anthony B.

    1991-01-01

    The feasibility of multiple spacecraft stationkeeping for submillimeter and optical interferometry is examined. A condition for interferometry is that two or more spacecraft must control their relative positions with better than 1 mn accuracy indefinitely in both radial and transverse directions although separated by as much as 1 Km in LEO and 100 Km in GEO. They must also maneuver through a useful area of the U-V plane of an arbitrary astronomical source. The problem is first outlined and a solution which utilizes gravity gradient forces to do most of the work and ion thrusters for additional maneuvering is proposed. All the perturbing forces are shown to be small compared to the ion thruster requirements. An inertial position and attitude control strategy is suggested which utilizes existing or soon to be available sensors and actuators. Finally, the fuel and power system mass requirements are estimated and found to be within reason for a 10 year mission.

  14. Stitching interferometry: recent results and absolute calibration

    NASA Astrophysics Data System (ADS)

    Bray, Michael

    2004-02-01

    Stitching Interferometry is a method of analysing large optical components using a standard "small" interferometer. This result is obtained by taking multiple overlapping images of the large component, and numerically "stitching" these sub-apertures together. We have already reported the industrial use our Stitching Interferometry systems (Previous SPIE symposia), but experimental results had been lacking because this technique is still new, and users needed to get accustomed to it before producing reliable measurements. We now have more results. We will report user comments and show new, unpublished results. We will discuss sources of error, and show how some of these can be reduced to arbitrarily small values. These will be discussed in some detail. We conclude with a few graphical examples of absolute measurements performed by us.

  15. Atom Interferometry in an Optical Cavity

    NASA Astrophysics Data System (ADS)

    Hamilton, Paul; Jaffe, Matt; Brown, Justin M.; Maisenbacher, Lothar; Estey, Brian; Müller, Holger

    2015-03-01

    We propose and demonstrate a new scheme for atom interferometry, using light pulses inside an optical cavity as matter wave beam splitters. The cavity provides power enhancement, spatial filtering, and a precise beam geometry, enabling new techniques such as low power beam splitters (<100 μ W ), large momentum transfer beam splitters with modest power, or new self-aligned interferometer geometries utilizing the transverse modes of the optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with >75 % contrast and measure the acceleration due to gravity, g , to 60 μ g /√{Hz } resolution in a Mach-Zehnder geometry. We use >107 cesium atoms in the compact mode volume (600 μ m 1 /e2 waist) of the cavity and show trapping of atoms in higher transverse modes. This work paves the way toward compact, high sensitivity, multiaxis interferometry.

  16. Coherence and interferometry through optical fibers

    NASA Astrophysics Data System (ADS)

    Froehly, C.

    Attention is given to the way in which the insertion of optical fibers on the arms of a stellar interferometer modifies the conditions of interference and the intensity patterns in the observation plane. This modification is compared with the usual situation, where the light propagates in the free space between the foci of the telescopes and the detection plane. This problem is considered for both single-mode and multimode fibers and for monochromatic and polychromatic radiation, that is, in 'partially coherent' light. A Fourier analysis is made of the spatiotemporal distortions of the scalar optical field propagating along the fibers; this makes it possible to calculate the complex correlations of the field introduced by the guide. The analysis is begun by considering interferometry through single-mode fibers. Orders of magnitude are given for practical fiber length limitations for white light interferometry, with an allowance made for the usual losses and performances of the fibers and spectroscopic devices commercially available today.

  17. Hidden observables in neutron quantum interferometry

    NASA Astrophysics Data System (ADS)

    Rauch, Helmut; Baron, Matthias; Filipp, Stefan; Hasegawa, Yuji; Lemmel, Hartmut; Loidl, Rudolf

    2006-11-01

    Neutron interferometry using monolithic perfect single crystals has become an important tool for fundamental, nuclear, and solid-state physics research. New features of quantum mechanics become measurable by means of neutron interferometry. Such features are quantum phases, which provide a more direct access to properties of wave functions and permit wave function reconstruction, and wave function engineering. Most recently, new experiments concerning off-diagonal and non-cyclic geometrical phases, confinement induced phases, and contextuality related experiments have been performed. These experiments show an intrinsic entanglement of different degrees of freedom of a single particle. Proper post-selection experiments yield to more quantum complete experiments and may help to make quantum mechanics less mystic. Unavoidable quantum losses may play an important role to explain the transition from the quantum to the classical world. All these investigations concern the heart of quantum mechanics and demonstrate the non-local feature of this theory.

  18. Use of interferometry in preschool children.

    PubMed

    Richman, J E; Kozol, N; Crawford, R D

    1989-05-01

    Any procedure that can help to predict the outcome of treatment for a vision disorder is a desired clinical goal. Interferometry has shown such an ability for predicting the post-treatment visual acuities in amblyopia and other vision disorders. In this study, we investigated the effectiveness of using interferometry with preschool children, aged 3-5 years. We determined that they can be reliably tested in 5-10 minutes using a non-verbal, forced choice technique. Due to developmental differences, the 3-year-olds needed slightly more time to test and were more variable in their responses than the 4-years-olds. Overall, the prognostic value of interferometer visual acuity measures should be considered for use in preschool children with visual acuity disorders, e.g., amblyopia. PMID:2732416

  19. Nanoscale optical interferometry with incoherent light

    PubMed Central

    Li, Dongfang; Feng, Jing; Pacifici, Domenico

    2016-01-01

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

  20. Infrasound Interferometry for Active and Passive Sources: A Synthetic Example for Waves Refracted in the Stratosphere

    NASA Astrophysics Data System (ADS)

    Fricke, J.; Ruigrok, E. N.; Evers, L. G.; El Allouche, N.; Simons, D.; Wapenaar, C. A.

    2012-12-01

    The travel time of infrasound through the stratosphere depends on the temperature profile and the wind speed. These atmospheric conditions can be estimated by determining the travel times between different receivers (microbarometers). Therefore the determination of the travel time of infrasound between different receivers becomes more and more important. An approach to determine the travel time is infrasound interferometry. In this work, the infrasound interferometry is applied to synthetic data of active and passive sources refracted by the stratosphere is tested. The synthetic data were generated with a raytracing model. The inputs of the raytracing model are the atmospheric conditions and a source wavelet. As source wavelet we used blast waves and microbaroms. With the atmospheric conditions and the source wavelet the raytracing model calculates the raypath and the travel time of the infrasound. In order to simulate the measurement of a receiver the rays which reach the receiver need to be found. The rays which propagate from a source to the receiver are called eigen rays. The simulation of the receiver measurements takes into account the travel time along the eigen rays, the attenuation of the different atmospheric layers, the spreading of the rays and the influence of caustics. The simulated measurements of the different receivers are combined to synthetic barograms. Two synthetic experiments were performed with the described model. In the first experiment the interferometry was applied to barograms of active sources like blast waves. The second experiment with microbaroms tests the applicability of interferometry to barograms of passive sources. In the next step infrasound interferometry will be applied to measured barograms. These barograms are measured with the 'Large Aperture Infrasound Array' (LAIA). LAIA is being installed by the Royal Netherlands Meteorological Institute (KNMI) in the framework of the radio-astronomical 'Low Frequency Array' (LOFAR

  1. Acoustic hemostasis

    NASA Astrophysics Data System (ADS)

    Crum, Lawrence; Beach, Kirk; Carter, Stephen; Chandler, Wayne; Curra, Francesco; Kaczkowski, Peter; Keilman, George; Khokhlova, Vera; Martin, Roy; Mourad, Pierre; Vaezy, Shahram

    2000-07-01

    In cases of severe injury, physicians speak of a "golden hour"—a brief grace period in which quickly applied, proper therapy can save the life of the patient. Much of this mortality results from exsanguination, i.e., bleeding to death—often from internal hemorrhage. The inability of a paramedic to treat breaches in the vascular system deep within the body or to stem the loss of blood from internal organs is a major reason for the high level of mortality associated with blunt trauma. We have undertaken an extensive research program to treat the problem of internal bleeding. Our approach is as follows: (a) We use scanning ultrasound to identify internal bleeding and hemorrhage, (b) we use ultrasound imaging to locate specific breaches in the vascular system, both from damaged vessels and gross damage to the capillary bed, and (c) we use High Intensity Focused Ultrasound (HIFU) to treat the damaged region and to induce hemostasis. We present a general review of this research with some emphasis on the role of nonlinear acoustics.

  2. Precision surveying using very long baseline interferometry

    NASA Technical Reports Server (NTRS)

    Ryan, J. W.; Clark, T. A.; Coates, R.; Ma, C.; Robertson, D. S.; Corey, B. E.; Counselman, C. C.; Shapiro, I. I.; Wittels, J. J.; Hinteregger, H. F.

    1977-01-01

    Radio interferometry measurements were used to measure the vector baselines between large microwave radio antennas. A 1.24 km baseline in Massachusetts between the 36 meter Haystack Observatory antenna and the 18 meter Westford antenna of Lincoln Laboratory was measured with 5 mm repeatability in 12 separate experiments. Preliminary results from measurements of the 3,928 km baseline between the Haystack antenna and the 40 meter antenna at the Owens Valley Radio Observatory in California are presented.

  3. Kaon decay interferometry as meson dynamics probes

    NASA Astrophysics Data System (ADS)

    D'ambrosio, G.; Paver, N.

    1994-05-01

    We discuss the time-dependent interferences between KL and KS in the decays in 3π and ππγ, to be studied at interferometry machines such as the φ factory and CERN LEAR. We emphasize the possibilities and the advantages of using interferences, in comparision with width measurements, to obtain information both on CP-conserving and CP-violating amplitudes. Comparision with present data and suggestions for future experiments are made.

  4. The Lindley paradox in optical interferometry

    NASA Astrophysics Data System (ADS)

    Mauri, Camillo; Paris, Matteo G. A.

    2016-02-01

    The so-called Lindley paradox is a counterintuitive statistical effect where the Bayesian and frequentist approaches to hypothesis testing give radically different answers, depending on the choice of the prior distribution. In this paper we address the occurrence of the Lindley paradox in optical interferometry and discuss its implications for high-precision measurements. In particular, we focus on phase estimation by Mach-Zehnder interferometers and show how to mitigate the conflict between the two approaches by using suitable priors.

  5. Rejection of RFI by means of interferometry

    NASA Technical Reports Server (NTRS)

    Dreher, J. W.

    1989-01-01

    The feasibility of using radio interferometry to reduce the levels of RF interference (RFI) encountered in the NASA Targeted Search SETI program is discussed. It is shown that a radio interferometer will be much less sensitive to RFI than a single antenna system. However, the use of an interferometer would entail a reduction in the noise-limited sensitivity of the system as well as some additional costs due to added complexity.

  6. Defect Depth Measurement Using White Light Interferometry

    NASA Technical Reports Server (NTRS)

    Parker, Don; Starr, Stan

    2009-01-01

    The objectives of the White Light Interferometry project are the following: (1) Demonstrate a small hand-held instrument capable of performing inspections of identified defects on Orbiter outer pane window surfaces. (2) Build and field-test a prototype device using miniaturized optical components. (3) Modify the instrument based on field testing and begin the conversion of the unit to become a certified shop-aid.

  7. Generalised receiver functions and seismic interferometry

    NASA Astrophysics Data System (ADS)

    Galetti, Erica; Curtis, Andrew

    2012-04-01

    Classical seismological receiver functions are correlational or deconvolutional combinations of vertical and horizontal component seismometer recordings of earthquake waves that focus information on near-receiver subsurface Earth structure and properties. We show that seismic interferometry can be thought of as a generalisation of receiver functions analysis to cases where recordings at pairs of receivers are considered simultaneously, and where either the same or different component recordings are combined. Further, seismic interferometry uses any of deconvolution, convolution and cross-correlation, and energy from either impulsive or random noise sources. We show both how receiver functions can logically be extended to a new, convolutional form, and that the now little-used correlational form of receiver functions contains more intuitive information than previously realised. Seismic interferometry has provided other extraordinary extensions to seismologists' arsenal. Passive noise recordings can be converted into seismograms from virtual (imagined) earthquakes that in turn can be used to image the real Earth. Active sources (e.g., earthquakes or man-made sources) can be redatumed into new, virtual sources elsewhere, or can be converted into virtual sensors (seismometers) that record seismograms from other real earthquakes, man-made sources or noise sources that occur either in the future or in the past. And the ability to construct virtual sources and sensors at desired times and locations (rather than having to wait for earthquake sources that occur at uncontrollable locations) promises more repeatable monitoring of changes in Earth subsurface properties over time. Indeed, so-called coda wave interferometry offers unprecedented accuracy in detecting such changes. Finally, existing theoretical extensions to other regimes such as electromagnetic, electrokinetic and diffusive energy propagation may lead to future revolutions in other domains of science.

  8. Moire interferometry for thermal expansion of composites

    NASA Technical Reports Server (NTRS)

    Bowles, D. E.; Tenney, D. R.; Post, D.; Herakovich, C. T.

    1981-01-01

    Moire interferometry by reflection has been demonstrated using a real reference grating of 1200 lines/mm. The method is shown to be well adapted to thermal environments. Thermal expansion coefficients of graphite-epoxy composites have been measured with high precision over a wide range from nearly zero to 3300 microstrains in the temperature range 297-422 K. Random errors characterized by one standard deviation can be as small as one microstrain.

  9. Interferometry theory for the block 2 processor

    NASA Technical Reports Server (NTRS)

    Thomas, J. B.

    1987-01-01

    Presented is the interferometry theory for the Block 2 processor, including a high-level functional description and a discussion of data structure. The analysis covers the major processing steps: cross-correlation, fringe counter-rotation, transformation to the frequency domain, phase calibration, bandwidth synthesis, and extraction of the observables of amplitude, phase, phase rate, and delay. Also included are analyses for fractional bitshift correction, station clock error, ionosphere correction, and effective frequencies for the observables.

  10. Gravitational wave detection using atom interferometry

    NASA Astrophysics Data System (ADS)

    Hogan, Jason

    2016-05-01

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

  11. Development of Speckle Interferometry Algorithm and System

    SciTech Connect

    Shamsir, A. A. M.; Jafri, M. Z. M.; Lim, H. S.

    2011-05-25

    Electronic speckle pattern interferometry (ESPI) method is a wholefield, non destructive measurement method widely used in the industries such as detection of defects on metal bodies, detection of defects in intergrated circuits in digital electronics components and in the preservation of priceless artwork. In this research field, this method is widely used to develop algorithms and to develop a new laboratory setup for implementing the speckle pattern interferometry. In speckle interferometry, an optically rough test surface is illuminated with an expanded laser beam creating a laser speckle pattern in the space surrounding the illuminated region. The speckle pattern is optically mixed with a second coherent light field that is either another speckle pattern or a smooth light field. This produces an interferometric speckle pattern that will be detected by sensor to count the change of the speckle pattern due to force given. In this project, an experimental setup of ESPI is proposed to analyze a stainless steel plate using 632.8 nm (red) wavelength of lights.

  12. Optical interferometry in fluid dynamics research

    NASA Technical Reports Server (NTRS)

    Bachalo, W. D.; Houser, M. J.

    1987-01-01

    Optical interferometry techniques were applied to the investigation of transonic airfoil flow fields in large wind tunnels. Holographic interferometry techniques were used to study 2 dimensional symmetric NACA 64A010 and Douglas Aircraft Co. DSMA671 supercritical airfoil performance in the NASA Ames 2 x 2 ft transonic wind tunnel. Quantitative data obtained from the interferograms were compared to the surface pressure data. The agreement obtained verified the accuracy of the flow visualization and demonstrated the potential for acquiring quantitative scalar results. Measurements of the inviscid flow speed and the boundary layer and wake velocity profiles were extracted from the interferograms and compared to laser Doppler velocimeter measurements. These results were also in good agreement. A method for acquiring real time interferometric data in large scale facilities was developed. This method, based on the point diffraction interferometer, was successfully tested in the 2 x 2 ft transonic wind tunnel. The holographic and real time interferometry methods were applied to the investigations of circulation control airfoils utilizing the Coanda effect. These results reveals the details of the jet interacting with the trailing edge boundary layer and the other parameters affecting the lift augmentation.

  13. Optical interferometry in fluid dynamics research

    NASA Technical Reports Server (NTRS)

    Bachalo, W. D.; Houser, M. J.

    1985-01-01

    Optical interferometry techniques have been applied to the investigation of transonic airfoil flow fields in large-scale wind tunnels. Holographic interferometry techniques were used in the study of two-dimensional symmetric NACA 64A010 and Douglas Aircraft Company DSMA671 supercritical airfoil performance in the NASA Ames 2 ft x 2 ft transonic wind tunnel. Quantitative data obtained from the interferograms were compared to the surface pressure data. The excellent agreement obtained verified the accuracy of the flow visualization and demonstrated the potential for acquiring quantitative scalar results. Measurements of the inviscid flow speed and the boundary layer and wake velocity profiles were extracted from the interferograms and compared to laser Doppler velocimeter measurements. These results were also in good agreement. A method for acquiring real-time interferometric data in large-scale facilities was developed. This method, based on the point diffraction interferometer, was successfully tested in the Ames 2 ft x 2 ft transonic wind tunnel. The holographic and real-time interferometry methods were applied to the investigations of circulation control airfoils utilizing the Coanda effect. These results revealed the details of the jet interaction with the trailing edge boundary layer and the other parameters affecting the lift augmentation.

  14. Two color holographic interferometry for microgravity application

    NASA Technical Reports Server (NTRS)

    Trolinger, James D.; Weber, David C.

    1995-01-01

    Holographic interferometry is a primary candidate for determining temperature and concentration in crystal growth experiments designed for space. The method measures refractive index changes within the fluid of an experimental test cell resulting from temperature and/or concentration changes. When the refractive index changes are caused by simultaneous temperature and concentration changes, the contributions of the two effects cannot be separated by single wavelength interferometry. By using two wavelengths, however, two independent interferograms can provide the additional independent equation required to determine the two unknowns. There is no other technique available that provides this type of information. The primary objectives of this effort were to experimentally verify the mathematical theory of two color holographic interferometry (TCHI) and to determine the practical value of this technique for space application. In the foregoing study, the theory of TCHI has been tested experimentally over a range of interest for materials processing in space where measurements of temperature and concentration in a solution are required. New techniques were developed and applied to stretch the limits beyond what could be done with existing procedures. The study resulted in the production of one of the most advanced, enhanced sensitivity holographic interferometers in existence. The interferometric measurements made at MSFC represent what is believed to be the most accurate holographic interferometric measurements made in a fluid to date. The tests have provided an understanding of the limitations of the technique in practical use.

  15. Development of Speckle Interferometry Algorithm and System

    NASA Astrophysics Data System (ADS)

    Shamsir, A. A. M.; Jafri, M. Z. M.; Lim, H. S.

    2011-05-01

    Electronic speckle pattern interferometry (ESPI) method is a wholefield, non destructive measurement method widely used in the industries such as detection of defects on metal bodies, detection of defects in intergrated circuits in digital electronics components and in the preservation of priceless artwork. In this research field, this method is widely used to develop algorithms and to develop a new laboratory setup for implementing the speckle pattern interferometry. In speckle interferometry, an optically rough test surface is illuminated with an expanded laser beam creating a laser speckle pattern in the space surrounding the illuminated region. The speckle pattern is optically mixed with a second coherent light field that is either another speckle pattern or a smooth light field. This produces an interferometric speckle pattern that will be detected by sensor to count the change of the speckle pattern due to force given. In this project, an experimental setup of ESPI is proposed to analyze a stainless steel plate using 632.8 nm (red) wavelength of lights.

  16. Two color holographic interferometry for microgravity application

    NASA Technical Reports Server (NTRS)

    Trolinger, James D.

    1993-01-01

    Holographic interferometry is a primary candidate for the measurement of temperature and concentration in various crystal growth experiments destined for space. The method measures refractive index changes in the experiment test cell. A refractive index change can be caused by concentration changes, temperature changes, or a combination of temperature and concentration changes. If the refractive index changes are caused by temperature and concentration changes occurring simultaneously in the experiment test cell, the contributions by the two effects cannot be separated by conventional measurement methods. By using two wavelengths, two independent interferograms can be produced from the reconstruction of the hologram. The two interferograms will be different due to dispersion properties of fluid materials. These differences provide the additional information that allows the separation of simultaneously occurring temperature and concentration gradients. There is no other technique available that can provide this type of information. The primary objectives of this effort are to experimentally verify the mathematical theory of two color holographic interferometry and to determine the practical value of this technique for space application. To achieve these objectives, the accuracy and sensitivity of the technique must be determined for geometry's and materials that are relevant to the Materials Processing in the Space program of NASA. This will be achieved through the use of a specially designed two-color holographic interferometry breadboard optical system. In addition to experiments to achieve the primary goals, the breadboard will also provide inputs to the design of an optimum space flight system.

  17. Atom Interferometry on a Sounding Rocket

    NASA Astrophysics Data System (ADS)

    Becker, Dennis; Seidel, Stephan; Lachmann, Maike; Rasel, Ernst; Quantus Collaboration

    2015-05-01

    The universality of free fall is one of the fundamental postulates of our description of nature. The comparison of the free fall of two ultra-cold clouds of different atomic species via atom interferometry comprises a method to precisely test this assumption. By performing the experiments in a microgravity environment the sensitivity of such an atom interferometric measurement can be increased. In order to fully utilize the potential of these experiments the usage of a Bose-Einstein condensate as the initial state of the atom interferometer is necessary. As a step towards the transfer of such a system in space an atom optical experiment is currently being prepared as the scientific payload for a sounding rocket mission. This mission is aiming at the first demonstration of a Bose-Einstein condensate in space and using this quantum degenerate matter as a source for atom interferometry. The launch of the rocket is planned for 2015 from ESRANGE. This first mission will be followed by two more that extend the scientific goals to the creation of degenerate mixtures in space and simultaneous atom interferometry with two atomic species. Their success would mark a major advancement towards a precise measurement of the universality of free fall with a space-born atom interferometer. This research is funded by the German Space Agency DLR under grant number DLR 50 1131-37.

  18. Comparing Laser Interferometry and Atom Interferometry Approaches to Space-Based Gravitational-Wave Measurement

    NASA Technical Reports Server (NTRS)

    Baker, John; Thorpe, Ira

    2012-01-01

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

  19. The AFGL image reconstruction program 2 speckle interferometry

    NASA Astrophysics Data System (ADS)

    Worden, S. P.; Hege, E. K.; Hubbard, E. N.; Woolf, N. J.; Strittmatter, P. A.

    1981-12-01

    Recent work indicates that large-telescope, optics-limited images are recoverable for objects as faint as +15 stellar magnitudes using a technique called speckle interferometry. This report presents a review of speckle interferometry, including current status and results. Section 2 provides a background of the Fourier mathematics used in image processing and optical systems. Section 3 describes how the atmosphere degrades astronomical images and how speckle interferometry has been used to recover high-resolution detail. Section 4 describes new work to recover actual optics-limited images, and compares active optics systems with speckle interferometry.

  20. Zeeman laser interferometry for detection and chemical analysis

    SciTech Connect

    Johnston, R.G.

    1993-12-01

    Zeeman interferometry has a number of applications for ultrasensitive detection and chemical analysis, including refractive index detection, micro-thermometry, thermooptic spectroscopy, and light scattering.

  1. Range-resolved signal processing for fibre segment interferometry applied to dynamic long-gauge length strain sensing

    NASA Astrophysics Data System (ADS)

    Kissinger, Thomas; Correia, Ricardo; Charrett, Thomas O. H.; James, Stephen W.; Tatam, Ralph P.

    2015-09-01

    A range-resolved interferometric signal processing technique using sinusoidal optical frequency modulation is applied to fibre segment interferometry. Here, six optical fibre segments of gauge length 12.5 cm are used as interferometric strain sensors and are formed between seven weak, broadband fibre Bragg gratings, acting as in-fibre partial reflectors. In a very simple and cost-effective optical setup using injection current modulation of a laser diode source, interferometric measurement of acoustic wave propagation in a metal rod is used to demonstrate the capabilities of the technique.

  2. Acoustic source for generating an acoustic beam

    DOEpatents

    Vu, Cung Khac; Sinha, Dipen N.; Pantea, Cristian

    2016-05-31

    An acoustic source for generating an acoustic beam includes a housing; a plurality of spaced apart piezo-electric layers disposed within the housing; and a non-linear medium filling between the plurality of layers. Each of the plurality of piezoelectric layers is configured to generate an acoustic wave. The non-linear medium and the plurality of piezo-electric material layers have a matching impedance so as to enhance a transmission of the acoustic wave generated by each of plurality of layers through the remaining plurality of layers.

  3. Acoustic Holography

    NASA Astrophysics Data System (ADS)

    Kim, Yang-Hann

    One of the subtle problems that make noise control difficult for engineers is the invisibility of noise or sound. A visual image of noise often helps to determine an appropriate means for noise control. There have been many attempts to fulfill this rather challenging objective. Theoretical (or numerical) means for visualizing the sound field have been attempted, and as a result, a great deal of progress has been made. However, most of these numerical methods are not quite ready for practical applications to noise control problems. In the meantime, rapid progress with instrumentation has made it possible to use multiple microphones and fast signal-processing systems. Although these systems are not perfect, they are useful. A state-of-the-art system has recently become available, but it still has many problematic issues; for example, how can one implement the visualized noise field. The constructed noise or sound picture always consists of bias and random errors, and consequently, it is often difficult to determine the origin of the noise and the spatial distribution of the noise field. Section 26.2 of this chapter introduces a brief history, which is associated with sound visualization, acoustic source identification methods and what has been accomplished with a line or surface array. Section 26.2.3 introduces difficulties and recent studies, including de-Dopplerization and de-re verberation methods, both essential for visualizing a moving noise source, such as occurs for cars or trains. This section also addresses what produces ambiguity in realizing real sound sources in a room or closed space. Another major issue associated with sound/noise visualization is whether or not we can distinguish between mutual dependencies of noise in space (Sect. 26.2.4); for example, we are asked to answer the question, Can we see two birds singing or one bird with two beaks?

  4. Acoustic Holography

    NASA Astrophysics Data System (ADS)

    Kim, Yang-Hann

    One of the subtle problems that make noise control difficult for engineers is the invisibility of noise or sound. A visual image of noise often helps to determine an appropriate means for noise control. There have been many attempts to fulfill this rather challenging objective. Theoretical (or numerical) means for visualizing the sound field have been attempted, and as a result, a great deal of progress has been made. However, most of these numerical methods are not quite ready for practical applications to noise control problems. In the meantime, rapid progress with instrumentation has made it possible to use multiple microphones and fast signal-processing systems. Although these systems are not perfect, they are useful. A state-of-the-art system has recently become available, but it still has many problematic issues; for example, how can one implement the visualized noise field. The constructed noise or sound picture always consists of bias and random errors, and consequently, it is often difficult to determine the origin of the noise and the spatial distribution of the noise field. Section 26.2 of this chapter introduces a brief history, which is associated with "sound visualization," acoustic source identification methods and what has been accomplished with a line or surface array. Section 26.2.3 introduces difficulties and recent studies, including de-Dopplerization and de-reverberation methods, both essentialfor visualizing a moving noise source, such as occurs for cars or trains. This section also addresses what produces ambiguity in realizing real sound sources in a room or closed space. Another major issue associated with sound/noise visualization is whether or not we can distinguish between mutual dependencies of noise in space (Sect. 26.2.4); for example, we are asked to answer the question, "Can we see two birds singing or one bird with two beaks?"

  5. Electronic speckle pattern interferometry and digital holographic interferometry with microbolometer arrays at 10.6 {mu}m

    SciTech Connect

    Vandenrijt, Jean-Francois; Georges, Marc P.

    2010-09-20

    Electronic speckle pattern interferometry and digital holographic interferometry are investigated at long infrared wavelengths. Using such wavelengths allows one to extend the measurement range and decrease the sensitivity of the techniques to external perturbations. We discuss the behavior of reflection by the object surfaces due to the long wavelength. We have developed different experimental configurations associating a CO2 laser emitting at 10.6{mu}m and microbolometer arrays. Phase-shifting in-plane and out-of-plane electronic speckle pattern interferometry and lensless digital holographic interferometry are demonstrated on rotation measurements of a solid object.

  6. What Is an Acoustic Neuroma

    MedlinePlus

    ... Acoustic Neuroma An acoustic neuroma, also called a vestibular schwannoma, is a rare benign tumor of the ... Acoustic Neuroma? An acoustic neuroma, known as a vestibular schwannoma, is a benign (non-cancerous) growth that ...

  7. Canonical Acoustics and Its Application to Surface Acoustic Wave on Acoustic Metamaterials

    NASA Astrophysics Data System (ADS)

    Shen, Jian Qi

    2016-08-01

    In a conventional formalism of acoustics, acoustic pressure p and velocity field u are used for characterizing acoustic waves propagating inside elastic/acoustic materials. We shall treat some fundamental problems relevant to acoustic wave propagation alternatively by using canonical acoustics (a more concise and compact formalism of acoustic dynamics), in which an acoustic scalar potential and an acoustic vector potential (Φ ,V), instead of the conventional acoustic field quantities such as acoustic pressure and velocity field (p,u) for characterizing acoustic waves, have been defined as the fundamental variables. The canonical formalism of the acoustic energy-momentum tensor is derived in terms of the acoustic potentials. Both the acoustic Hamiltonian density and the acoustic Lagrangian density have been defined, and based on this formulation, the acoustic wave quantization in a fluid is also developed. Such a formalism of acoustic potentials is employed to the problem of negative-mass-density assisted surface acoustic wave that is a highly localized surface bound state (an eigenstate of the acoustic wave equations). Since such a surface acoustic wave can be strongly confined to an interface between an acoustic metamaterial (e.g., fluid-solid composite structures with a negative dynamical mass density) and an ordinary material (with a positive mass density), it will give rise to an effect of acoustic field enhancement on the acoustic interface, and would have potential applications in acoustic device design for acoustic wave control.

  8. Symptoms of Acoustic Neuroma

    MedlinePlus

    ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ... Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions to Ask Yourself ...

  9. Phonon counting and intensity interferometry of a nanomechanical resonator

    NASA Astrophysics Data System (ADS)

    Cohen, Justin D.; Meenehan, Seán M.; Maccabe, Gregory S.; Gröblacher, Simon; Safavi-Naeini, Amir H.; Marsili, Francesco; Shaw, Matthew D.; Painter, Oskar

    2015-04-01

    In optics, the ability to measure individual quanta of light (photons) enables a great many applications, ranging from dynamic imaging within living organisms to secure quantum communication. Pioneering photon counting experiments, such as the intensity interferometry performed by Hanbury Brown and Twiss to measure the angular width of visible stars, have played a critical role in our understanding of the full quantum nature of light. As with matter at the atomic scale, the laws of quantum mechanics also govern the properties of macroscopic mechanical objects, providing fundamental quantum limits to the sensitivity of mechanical sensors and transducers. Current research in cavity optomechanics seeks to use light to explore the quantum properties of mechanical systems ranging in size from kilogram-mass mirrors to nanoscale membranes, as well as to develop technologies for precision sensing and quantum information processing. Here we use an optical probe and single-photon detection to study the acoustic emission and absorption processes in a silicon nanomechanical resonator, and perform a measurement similar to that used by Hanbury Brown and Twiss to measure correlations in the emitted phonons as the resonator undergoes a parametric instability formally equivalent to that of a laser. Owing to the cavity-enhanced coupling of light with mechanical motion, this effective phonon counting technique has a noise equivalent phonon sensitivity of 0.89 +/- 0.05. With straightforward improvements to this method, a variety of quantum state engineering tasks using mesoscopic mechanical resonators would be enabled, including the generation and heralding of single-phonon Fock states and the quantum entanglement of remote mechanical elements.

  10. Phonon counting and intensity interferometry of a nanomechanical resonator.

    PubMed

    Cohen, Justin D; Meenehan, Seán M; MacCabe, Gregory S; Gröblacher, Simon; Safavi-Naeini, Amir H; Marsili, Francesco; Shaw, Matthew D; Painter, Oskar

    2015-04-23

    In optics, the ability to measure individual quanta of light (photons) enables a great many applications, ranging from dynamic imaging within living organisms to secure quantum communication. Pioneering photon counting experiments, such as the intensity interferometry performed by Hanbury Brown and Twiss to measure the angular width of visible stars, have played a critical role in our understanding of the full quantum nature of light. As with matter at the atomic scale, the laws of quantum mechanics also govern the properties of macroscopic mechanical objects, providing fundamental quantum limits to the sensitivity of mechanical sensors and transducers. Current research in cavity optomechanics seeks to use light to explore the quantum properties of mechanical systems ranging in size from kilogram-mass mirrors to nanoscale membranes, as well as to develop technologies for precision sensing and quantum information processing. Here we use an optical probe and single-photon detection to study the acoustic emission and absorption processes in a silicon nanomechanical resonator, and perform a measurement similar to that used by Hanbury Brown and Twiss to measure correlations in the emitted phonons as the resonator undergoes a parametric instability formally equivalent to that of a laser. Owing to the cavity-enhanced coupling of light with mechanical motion, this effective phonon counting technique has a noise equivalent phonon sensitivity of 0.89 ± 0.05. With straightforward improvements to this method, a variety of quantum state engineering tasks using mesoscopic mechanical resonators would be enabled, including the generation and heralding of single-phonon Fock states and the quantum entanglement of remote mechanical elements. PMID:25903632

  11. Acoustic emission frequency discrimination

    NASA Technical Reports Server (NTRS)

    Sugg, Frank E. (Inventor); Graham, Lloyd J. (Inventor)

    1988-01-01

    In acoustic emission nondestructive testing, broadband frequency noise is distinguished from narrow banded acoustic emission signals, since the latter are valid events indicative of structural flaws in the material being examined. This is accomplished by separating out those signals which contain frequency components both within and beyond (either above or below) the range of valid acoustic emission events. Application to acoustic emission monitoring during nondestructive bond verification and proof loading of undensified tiles on the Space Shuttle Orbiter is considered.

  12. Acoustically Evoked Different Vibration Pattern Across the Width of the Cochlea Partition

    NASA Astrophysics Data System (ADS)

    Zha, Dingjun; Chen, Fangyi; Friderberg, Anders; Choudhury, Niloy; Nuttall, Alfred

    2011-11-01

    Using optical low coherence interferometry, the acoustically evoked vibration patterns of the basilar membrane (BM) and reticular lamina (RL) in the first turn of living guinea pigs were measured as function of the radial location. It was demonstrated that the vibration of the BM varied widely in amplitude, but little in phase across the width of the partition, while the RL had a different vibration pattern compared with the BM.

  13. Tutorial on architectural acoustics

    NASA Astrophysics Data System (ADS)

    Shaw, Neil; Talaske, Rick; Bistafa, Sylvio

    2002-11-01

    This tutorial is intended to provide an overview of current knowledge and practice in architectural acoustics. Topics covered will include basic concepts and history, acoustics of small rooms (small rooms for speech such as classrooms and meeting rooms, music studios, small critical listening spaces such as home theatres) and the acoustics of large rooms (larger assembly halls, auditoria, and performance halls).

  14. Atom Interferometry for Fundamental Physics and Gravity Measurements in Space

    NASA Technical Reports Server (NTRS)

    Kohel, James M.

    2012-01-01

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

  15. Phase-Shift Interferometry with a Digital Photocamera

    ERIC Educational Resources Information Center

    Vannoni, Maurizio; Trivi, Marcelo; Molesini, Giuseppe

    2007-01-01

    A phase-shift interferometry experiment is proposed, working on a Twyman-Green optical configuration with additional polarization components. A guideline is provided to modern phase-shift interferometry, using concepts and laboratory equipment at the level of undergraduate optics courses. (Contains 5 figures.)

  16. Applying the seismic interferometry method to vertical seismic profile data using tunnel excavation noise as source

    NASA Astrophysics Data System (ADS)

    Jurado, Maria Jose; Teixido, Teresa; Martin, Elena; Segarra, Miguel; Segura, Carlos

    2013-04-01

    response and the reflection response for a 1D multilayer structure, and next 3D approach (Wapenaar 2004). As a result of this seismic interferometry experiment the 3D reflectivity model (frequencies and resolution ranges) was obtained. We proved also that the seismic interferometry approach can be applied in asynchronous seismic auscultation. The reflections detected in the virtual seismic sections are in agreement with the geological features encountered during the excavation of the tunnel and also with the petrophysical properties and parameters measured in previous geophysical borehole logging. References Claerbout J.F., 1968. Synthesis of a layered medium from its acoustic transmision response. Geophysics, 33, 264-269 Flavio Poletto, Piero Corubolo and Paolo Comeli.2010. Drill-bit seismic interferometry whith and whitout pilot signals. Geophysical Prospecting, 2010, 58, 257-265. Wapenaar, K., J. Thorbecke, and D. Draganov, 2004, Relations between reflection and transmission responses of three-dimensional inhomogeneous media: Geophysical Journal International, 156, 179-194.

  17. Reflection imaging of the Moon's interior using deep-moonquake seismic interferometry

    NASA Astrophysics Data System (ADS)

    Nishitsuji, Yohei; Rowe, C. A.; Wapenaar, Kees; Draganov, Deyan

    2016-04-01

    The internal structure of the Moon has been investigated over many years using a variety of seismic methods, such as travel time analysis, receiver functions, and tomography. Here we propose to apply body-wave seismic interferometry to deep moonquakes in order to retrieve zero-offset reflection responses (and thus images) beneath the Apollo stations on the nearside of the Moon from virtual sources colocated with the stations. This method is called deep-moonquake seismic interferometry (DMSI). Our results show a laterally coherent acoustic boundary around 50 km depth beneath all four Apollo stations. We interpret this boundary as the lunar seismic Moho. This depth agrees with Japan Aerospace Exploration Agency's (JAXA) SELenological and Engineering Explorer (SELENE) result and previous travel time analysis at the Apollo 12/14 sites. The deeper part of the image we obtain from DMSI shows laterally incoherent structures. Such lateral inhomogeneity we interpret as representing a zone characterized by strong scattering and constant apparent seismic velocity at our resolution scale (0.2-2.0 Hz).

  18. Dynamic 3D imaging based on acousto-optic heterodyne fringe interferometry.

    PubMed

    Guan, Yingjian; Yin, Yongkai; Li, Ameng; Liu, Xiaoli; Peng, Xiang

    2014-06-15

    An acoustic-optics heterodyne fringe interferometry coupled with a three-camera system is developed for dynamic 3D imaging. In this system, first-order beams with a slight frequency difference diffracted from two acousto-optic deflectors (AODs) form a beat intensity fringe pattern. Setting the frequency of the trigger signal for the CCD cameras into four times the beat frequency, four-step phase-shifting fringe patterns can be obtained, and the wrapped phase map (WPM) can be calculated. Under the epipolar constraint among three cameras, the homologous points can be determined unambiguously with the assistant of a WPM; thus the 3D shape can be reconstructed while skipping the phase unwrapping step. Experimental results are presented to validate this approach. PMID:24978566

  19. All-fiber ultrasound sensor array implemented by swept frequency interferometry

    NASA Astrophysics Data System (ADS)

    Gabai, Haniel; Steinberg, Idan; Shiloh, Lihi; Eyal, Avishay

    2015-09-01

    Fiber ultrasound (US) sensing is gaining popularity in recent years. Unique characteristics such as immunity to electromagnetic interference and embedding compatibility makes them advantageous in many applications. Multiplexing of US fiber sensors, however, remains a challenge. Here, a new multiplexing approach is introduced. Based on Swept Frequency Interferometry (SFI), it enables practical multiplexing of tens of US sensors. For demonstration, a 3-sensors setup was excited by ultrasound tone-bursts. While using low driving voltage (2.5-10V vs. ~100-400V in similar studies) and not implementing acoustic-impedance optimization or optical-resonance sensitivity enhancement, the sensors detected the excitation with high SNR (~25dB).

  20. Ultrafast high strain rate acoustic wave measurements at high static pressure in a diamond anvil cell

    SciTech Connect

    Armstrong, M; Crowhurst, J; Reed, E; Zaug, J

    2008-02-04

    We have used sub-picosecond laser pulses to launch ultra-high strain rate ({approx} 10{sup 9} s{sup -1}) nonlinear acoustic waves into a 4:1 methanol-ethanol pressure medium which has been precompressed in a standard diamond anvil cell. Using ultrafast interferometry, we have characterized acoustic wave propagation into the pressure medium at static compression up to 24 GPa. We find that the velocity is dependent on the incident laser fluence, demonstrating a nonlinear acoustic response which may result in shock wave behavior. We compare our results with low strain, low strain-rate acoustic data. This technique provides controlled access to regions of thermodynamic phase space that are otherwise difficult to obtain.

  1. Detection of nonlinear picosecond acoustic pulses by time-resolved Brillouin scattering

    SciTech Connect

    Gusev, Vitalyi E.

    2014-08-14

    In time-resolved Brillouin scattering (also called picosecond ultrasonic interferometry), the time evolution of the spatial Fourier component of an optically excited acoustic strain distribution is monitored. The wave number is determined by the momentum conservation in photon-phonon interaction. For linear acoustic waves propagating in a homogeneous medium, the detected time-domain signal of the optical probe transient reflectivity shows a sinusoidal oscillation at a constant frequency known as the Brillouin frequency. This oscillation is a result of heterodyning the constant reflection from the sample surface with the Brillouin-scattered field. Here, we present an analytical theory for the nonlinear reshaping of a propagating, finite amplitude picosecond acoustic pulse, which results in a time-dependence of the observed frequency. In particular, we examine the conditions under which this information can be used to study the time-evolution of the weak-shock front speed. Depending on the initial strain pulse parameters and the time interval of its nonlinear transformation, our theory predicts the detected frequency to either be monotonically decreasing or oscillating in time. We support these theoretical predictions by comparison with available experimental data. In general, we find that picosecond ultrasonic interferometry of nonlinear acoustic pulses provides access to the nonlinear acoustic properties of a medium spanning most of the GHz frequency range.

  2. Feasibility of satellite interferometry for surveillance, navigation, and traffic control

    NASA Technical Reports Server (NTRS)

    Gopalapillai, S.; Ruck, G. T.; Mourad, A. G.

    1976-01-01

    The feasibility of using a satellite borne interferometry system for surveillance, navigation, and traffic control applications was investigated. The evaluation was comprised of: (1) a two part systems analysis (software and hardware); (2) a survey of competitive navigation systems (both experimental and planned); (3) a comparison of their characteristics and capabilities with those of an interferometry system; and (4) a limited survey of potential users to determine the variety of possible applications for the interferometry system and the requirements which it would have to meet. Five candidate or "strawman" interferometry systems for various applications with various capabilities were configured (on a preliminary basis) and were evaluated. It is concluded that interferometry in conjunction with a geostationary satellite has an inherent ability to provide both a means for navigation/position location and communication. It offers a very high potential for meeting a large number of user applications and requirements for navigation and related functions.

  3. Report on ''European Radio Interferometry School 2015''

    NASA Astrophysics Data System (ADS)

    Laing, R.; Richards, A.

    2016-03-01

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

  4. The critical angle in seismic interferometry

    USGS Publications Warehouse

    Van Wijk, K.; Calvert, A.; Haney, M.; Mikesell, D.; Snieder, R.

    2008-01-01

    Limitations with respect to the characteristics and distribution of sources are inherent to any field seismic experiment, but in seismic interferometry these lead to spurious waves. Instead of trying to eliminate, filter or otherwise suppress spurious waves, crosscorrelation of receivers in a refraction experiment indicate we can take advantage of spurious events for near-surface parameter extraction for static corrections or near-surface imaging. We illustrate this with numerical examples and a field experiment from the CSM/Boise State University Geophysics Field Camp.

  5. Damage Detection Using Holography and Interferometry

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    2003-01-01

    This paper reviews classical approaches to damage detection using laser holography and interferometry. The paper then details the modern uses of electronic holography and neural-net-processed characteristic patterns to detect structural damage. The design of the neural networks and the preparation of the training sets are discussed. The use of a technique to optimize the training sets, called folding, is explained. Then a training procedure is detailed that uses the holography-measured vibration modes of the undamaged structures to impart damage-detection sensitivity to the neural networks. The inspections of an optical strain gauge mounting plate and an International Space Station cold plate are presented as examples.

  6. Enhanced spectral resolution via externally dispersed interferometry

    NASA Astrophysics Data System (ADS)

    Edelstein, Jerry; Erskine, David; Sirk, Martin; Vanderburg, Andrew; Wishnow, Edward H.

    2012-09-01

    Externally dispersed interferometry (EDI) uses a hybrid spectrometer that combines a Michelson interferometer in series with a grating spectrometer. EDI provides a means of deriving spectral information at a resolution substantially higher than that provided by the grating spectrograph alone. Near IR observations have been conducted using the Triplespec spectrometer mounted on the 5m Hale telescope. Spectra have been reconstructed at a resolution of ~27000 where the resolution of Triplespec is ~2700. Progress in the development of the EDI technique is reported herein emphasizing studies related to the accuracy of the reconstructed spectra.

  7. Probing dark energy with atom interferometry

    NASA Astrophysics Data System (ADS)

    Burrage, Clare; Copeland, Edmund J.; Hinds, E. A.

    2015-03-01

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

  8. Geometric-phase atom optics and interferometry

    NASA Astrophysics Data System (ADS)

    Zygelman, B.

    2015-10-01

    We illustrate how geometric gauge forces and topological phase effects emerge in atomic and molecular systems without employing assumptions that rely on adiabaticity. We show how geometric magnetism may be harnessed to engineer novel quantum devices including a velocity sieve, a component in mass spectrometers, for neutral atoms. We introduce and outline a possible experimental setup that demonstrates topological interferometry for neutral spin-1/2 systems. For that two-level system, we study the transition from Abelian to non-Abelian behavior and explore its relation to the molecular Aharonov-Bohm effect.

  9. A simple laser system for atom interferometry

    NASA Astrophysics Data System (ADS)

    Merlet, S.; Volodimer, L.; Lours, M.; Pereira Dos Santos, F.

    2014-07-01

    We present here a simple laser system for a laser-cooled atom interferometer, where all functions (laser cooling, interferometry and detection) are realized using only two extended cavity laser diodes, amplified by a common tapered amplifier. One laser is locked by frequency modulation transfer spectroscopy, the other being phase locked with an offset frequency determined by an field-programmable gate array-controlled direct digital synthesizer, which allows for efficient and versatile tuning of the laser frequency. Raman lasers are obtained with a double pass acoustooptic modulator. We demonstrate a gravimeter using this laser system, with performances close to the state of the art.

  10. Phase contrast laminography based on Talbot interferometry.

    PubMed

    Altapova, Venera; Helfen, Lukas; Myagotin, Anton; Hänschke, Daniel; Moosmann, Julian; Gunneweg, Jan; Baumbach, Tilo

    2012-03-12

    Synchrotron laminography is combined with Talbot grating interferometry to address weakly absorbing specimens. Integrating both methods into one set-up provides a powerful x-ray diagnostical technique for multiple contrast screening of macroscopically large flat specimen and a subsequent non-destructive three-dimensional (3-D) inspection of regions of interest. The technique simultaneously yields the reconstruction of the 3-D absorption, phase, and the so-called dark-field contrast maps. We report on the theoretical and instrumental implementation of of this novel technique. Its broad application potential is exemplarily demonstrated for the field of cultural heritage, namely study of the historical Dead Sea parchment. PMID:22418532

  11. MAXIM Pathfinder x-ray interferometry mission

    NASA Astrophysics Data System (ADS)

    Gendreau, Keith C.; Cash, Webster C.; Shipley, Ann F.; White, Nicholas

    2003-03-01

    The MAXIM Pathfinder (MP) mission is under study as a scientific and technical stepping stone for the full MAXIM X-ray interferometry mission. While full MAXIM will resolve the event horizons of black holes with 0.1 microarcsecond imaging, MP will address scientific and technical issues as a 100 microarcsecond imager with some capabilities to resolve microarcsecond structure. We will present the primary science goals of MP. These include resolving stellar coronae, distinguishing between jets and accretion disks in AGN. This paper will also present the baseline design of MP. We will overview the challenging technical requirements and solutions for formation flying, target acquisition, and metrology.

  12. Spaceborne radar interferometry for coastal DEM construction

    USGS Publications Warehouse

    Hong, S.-H.; Lee, C.-W.; Won, J.-S.; Kwoun, Oh-Ig; Lu, Zhiming

    2005-01-01

    Topographic features in coastal regions including tidal flats change more significantly than landmass, and are characterized by extremely low slopes. High precision DEMs are required to monitor dynamic changes in coastal topography. It is difficult to obtain coherent interferometric SAR pairs especially over tidal flats mainly because of variation of tidal conditions. Here we focus on i) coherence of multi-pass ERS SAR interferometric pairs and ii) DEM construction from ERS-ENVISAT pairs. Coherences of multi-pass ERS interferograms were good enough to construct DEM under favorable tidal conditions. Coherence in sand dominant area was generally higher than that in muddy surface. The coarse grained coastal areas are favorable for multi-pass interferometry. Utilization of ERS-ENVISAT interferometric pairs is taken a growing interest. We carried out investigation using a cross-interferometric pair with a normal baseline of about 1.3 km, a 30 minutes temporal separation and the height sensitivity of about 6 meters. Preliminary results of ERS-ENVISAT interferometry were not successful due to baseline and unfavorable scattering conditions. ?? 2005 IEEE.

  13. Interferometry-based Kolsky bar apparatus

    NASA Astrophysics Data System (ADS)

    Avinadav, C.; Ashuach, Y.; Kreif, R.

    2011-07-01

    A new experimental approach of the Kolsky bar system using optical interferometry is presented for determination of dynamic behavior of materials. Conventional measurements in the Kolsky bar system are based on recording the strain histories on the incident and transmitter bars with two strain gauges, and require good adhesion between the gauge and the bar. We suggest an alternative approach, based on measuring the actual velocities of the bars by using fiber-based velocity interferometry. Two fiber focusers illuminate the bars at a small angle and collect reflected Doppler-shifted light, which is interfered with a reference beam. Velocities are calculated from short-time Fourier transform and phase-based analysis, and the dynamic stress-strain curve is derived directly from the measured velocity traces. We demonstrate that the results coincide with those obtained by conventional strain gauge measurements. The new method is non-intervening and thus not affected by bar impacts, making it more robust and reliable than strain gauges.

  14. Testing the equivalence principle with atomic interferometry

    NASA Astrophysics Data System (ADS)

    Herrmann, Sven; Dittus, Hansjörg; Lämmerzahl, Claus; pre="the" post=""> QUANTUS,

    2012-09-01

    The weak equivalence principle (WEP), that is, the universality of free fall, states that all point-like neutral particles in a gravitational field fall in the same way. This is the basis of the geometrization of the gravitational interaction. Together with further requirements on the behavior of point particles, light propagation and clocks one can show that gravity is modeled by a Riemannian geometry. Since in the quantum domain all objects are extended, it is not clear whether the notion of a WEP in the quantum domain makes sense at all. We show that for matter wave interferometry the notion of WEP still can be given a meaning. We give a short overview over schemes which allows a violation of the WEP and emphasize that there are also schemes which show that there might be violations of the WEP in the quantum regime which are not present classically. This makes a test of the WEP with quantum matter necessary. We also give a brief outline of the efforts made for testing the WEP with interferometry with cold atoms in the Bremen drop tower carried out by the QUANTUS and PRIMUS collaboration.

  15. Non-Abelian Anyons and Interferometry

    NASA Astrophysics Data System (ADS)

    Bonderson, Parsa Hassan

    This thesis is primarily a study of the measurement theory of non-Abelian anyons through interference experiments. We give an introduction to the theory of anyon models, providing all the formalism necessary to apply standard quantum measurement theory to such systems. This formalism is then applied to give a detailed analysis of a Mach-Zehnder interferometer for arbitrary anyon models. In this treatment, we find that the collapse behavior exhibited by a target anyon in a superposition of states is determined by the monodromy of the probe anyons with the target. Such measurements may also be used to gain knowledge that would help to properly identify the anyon model describing an unknown system. The techniques used and results obtained from this model interferometer have general applicability, and we use them to also describe the interferometry measurements in a two point-contact interferometer proposed for non-Abelian fractional quantum Hall states. Additionally, we give the complete description of a number of important examples of anyon models, as well as their corresponding quantities that are relevant for interferometry. Finally, we give a partial classification of anyon models with small numbers of particle types.

  16. Is Space-based Interferometry Dead?

    NASA Astrophysics Data System (ADS)

    Leisawitz, David; Benford, D.; Blain, A.; Carr, J.; Fich, M.; Fischer, J.; Goldsmith, P.; Greaves, J.; Griffin, M.; Helou, G.; Ivison, R.; Kuchner, M.; Lyon, R.; Matsuo, H.; Rinehart, S. A.; Serabyn, E.; Shibai, H.; Silverberg, R.; Staguhn, J.; Unwin, S.; Wilner, D.; Wootten, A.; Wright, E. L.

    2011-05-01

    In the wake of the Decadal Survey and a January 2011 meeting of NASA's Exoplanet Exploration Program Analysis Group (ExoPAG), one might be tempted to conclude that space interferometry is dead. We explain why this slogan is hyperbole, summarize the steps currently being taken to prepare for a space-based far-IR interferometer, and reiterate the science case for an imaging and spectroscopic interferometer - SPIRIT - that would operate in space at long infrared wavelengths. Space-based interferometry is alive and well, but the center of activity has shifted to a spectral region (25 to 400 microns) in which no alternative measurement technique can provide information essential to answering several scientific questions deemed compelling by the Decadal Survey. Astrophysicists will use SPIRIT to: discover how the conditions for habitability arise during planetary system formation; find and characterize exoplanets by measuring their sculpting effects on protoplanetary and debris disks; and study the formation, merger history, and star formation history of galaxies.

  17. Using atom interferometry to detect dark energy

    NASA Astrophysics Data System (ADS)

    Burrage, Clare; Copeland, Edmund J.

    2016-04-01

    We review the tantalising prospect that the first evidence for the dark energy driving the observed acceleration of the universe on giga-parsec scales may be found through metre scale laboratory-based atom interferometry experiments. To do that, we first introduce the idea that scalar fields could be responsible for dark energy and show that in order to be compatible with fifth force constraints, these fields must have a screening mechanism which hides their effects from us within the solar system. Particular emphasis is placed on one such screening mechanism known as the chameleon effect where the field's mass becomes dependent on the environment. The way the field behaves in the presence of a spherical source is determined and we then go on to show how in the presence of the kind of high vacuum associated with atom interferometry experiments, and when the test particle is an atom, it is possible to use the associated interference pattern to place constraints on the acceleration due to the fifth force of the chameleon field - this has already been used to rule out large regions of the chameleon parameter space and maybe one day will be able to detect the force due to the dark energy field in the laboratory.

  18. Deflectometry challenges interferometry: the competition gets tougher!

    NASA Astrophysics Data System (ADS)

    Faber, Christian; Olesch, Evelyn; Krobot, Roman; Häusler, Gerd

    2012-09-01

    Deflectometric methods that are capable of providing full-field topography data for specular freeform surfaces have been around for more than a decade. They have proven successful in various fields of application, such as the measurement of progressive power eyeglasses, painted car body panels, or windshields. However, up to now deflectometry has not been considered as a viable competitor to interferometry, especially for the qualification of optical components. The reason is that, despite the unparalleled local sensitivity provided by deflectometric methods, the global height accuracy attainable with this measurement technique used to be limited to several microns over a field of 100 mm. Moreover, spurious reflections at the rear surface of transparent objects could easily mess up the measured signal completely. Due to new calibration and evaluation procedures, this situation has changed lately. We will give a comparative assessment of the strengths and - now partly revised - weaknesses of both measurement principles from the current perspective. By presenting recent developments and measurement examples from different applications, we will show that deflectometry is now heading to become a serious competitor to interferometry.

  19. AST Launch Vehicle Acoustics

    NASA Technical Reports Server (NTRS)

    Houston, Janice; Counter, D.; Giacomoni, D.

    2015-01-01

    The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible pre-launch test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments and to determine the acoustic reduction with an above deck water sound suppression system. The SMAT was conducted at Marshall Space Flight Center and the test article included a 5% scale SLS vehicle model, tower and Mobile Launcher. Acoustic and pressure data were measured by approximately 250 instruments. The SMAT liftoff acoustic results are presented, findings are discussed and a comparison is shown to the Ares I Scale Model Acoustic Test (ASMAT) results.

  20. Acoustic Translation of an Acoustically Levitated Sample

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Allen, J. L.

    1986-01-01

    Acoustic-levitation apparatus uses only one acoustic mode to move sample from one region of chamber to another. Sample heated and cooled quickly by translation between hot and cold regions of levitation chamber. Levitated sample is raised into furnace region by raising plunger. Frequency of sound produced by transducers adjusted by feedback system to maintain (102) resonant mode, which levitates sample midway between transducers and plunger regardless of plunger position.

  1. The Wide-Field Imaging Interferometry Testbed: Recent Progress

    NASA Technical Reports Server (NTRS)

    Rinehart, Stephen A.

    2010-01-01

    The Wide-Field Imaging Interferometry Testbed (WIIT) at NASA's Goddard Space Flight Center was designed to demonstrate the practicality and application of techniques for wide-field spatial-spectral ("double Fourier") interferometry. WIIT is an automated system, and it is now producing substantial amounts of high-quality data from its state-of-the-art operating environment, Goddard's Advanced Interferometry and Metrology Lab. In this paper, we discuss the characterization and operation of the testbed and present the most recent results. We also outline future research directions. A companion paper within this conference discusses the development of new wide-field double Fourier data analysis algorithms.

  2. Calibration and imaging algorithms for full-Stokes optical interferometry

    NASA Astrophysics Data System (ADS)

    Elias, Nicholas M.; Mozurkewich, David; Schmidt, Luke M.; Jurgenson, Colby A.; Edel, Stanislav S.; Jones, Carol E.; Halonen, Robert J.; Schmitt, Henrique R.; Jorgensen, Anders M.; Hutter, Donald J.

    2012-07-01

    Optical interferometry and polarimetry have separately provided new insights into stellar astronomy, especially in the fields of fundamental parameters and atmospheric models. Optical interferometers will eventually add full-Stokes polarization measuring capabilities, thus combining both techniques. In this paper, we: 1) list the observables, calibration quantities, and data acquisition strategies for both limited and full optical interferometric polarimetry (OIP); 2) describe the masking interferometer AMASING and its polarization measuring enhancement called AMASING-POL; 3) show how a radio interferometry imaging package, CASA, can be used for optical interferometry data reduction; and 4) present imaging simulations for Be stars.

  3. Status of holographic interferometry at Wright Patterson Air Force Base

    NASA Technical Reports Server (NTRS)

    Seibert, George

    1987-01-01

    At Wright Patterson AFB, holographic interferometry has been used for nearly 15 years in a variety of supersonic and hypersonic wind tunnels. Specifically, holographic interferometry was used to study boundary layers, shock boundary layer interaction, and general flow diagnostics. Although a considerable amount of quantitative work was done, the difficulty of reducing data severely restricted this. In the future, it is of interest to use holographic interferometry in conjunction with laser Doppler velocimetry to do more complete diagnostics. Also, there is an interest to do particle field diagnostics in the combustion research facility. Finally, there are efforts in nondestructive testing where automated fringe readout and analysis would be extremely helpful.

  4. Nonlinear Acoustics in Fluids

    NASA Astrophysics Data System (ADS)

    Lauterborn, Werner; Kurz, Thomas; Akhatov, Iskander

    At high sound intensities or long propagation distances at in fluids sufficiently low damping acoustic phenomena become nonlinear. This chapter focuses on nonlinear acoustic wave properties in gases and liquids. The origin of nonlinearity, equations of state, simple nonlinear waves, nonlinear acoustic wave equations, shock-wave formation, and interaction of waves are presented and discussed. Tables are given for the nonlinearity parameter B/A for water and a range of organic liquids, liquid metals and gases. Acoustic cavitation with its nonlinear bubble oscillations, pattern formation and sonoluminescence (light from sound) are modern examples of nonlinear acoustics. The language of nonlinear dynamics needed for understanding chaotic dynamics and acoustic chaotic systems is introduced.

  5. Monitoring gas reservoirs by seismic interferometry

    NASA Astrophysics Data System (ADS)

    Grigoli, Francesco; Cesca, Simone; Sens-Schoenfelder, Christoph; Priolo, Enrico

    2014-05-01

    Ambient seismic noise can be used to image spatial anomalies in the subsurface, without the need of recordings from seismic sources, such as earthquakes or explosions. Furthermore, the temporal variation of ambient seismic noise's can be used to infer temporal changes of the seismic velocities in the investigated medium. Such temporal variations can reflect changes of several physical properties/conditions in the medium. For example, they may be consequence of stress changes, variation of hydrogeological parameters, pore pressure and saturation changes due to fluid injection or extraction. Passive image interferometry allows to continuously monitor small temporal changes of seismic velocities in the subsurface, making it a suitable tool to monitor time-variant systems such as oil and gas reservoirs or volcanic environments. The technique does not require recordings from seismic sources in the classical sense, but is based on the processing of noise records. Moreover, it requires only data from one or two seismic stations, their locations constraining the sampled target area. Here we apply passive image interferometry to monitor a gas storage reservoir in northern Italy. The Collalto field (Northern Italy) is a depleted gas reservoir located at 1500 m depth, now used as a gas storage facility. The reservoir experience a significant temporal variation in the amount of stored gas: the injection phases mainly occur in the summer, while the extraction take place mostly in winter. In order to monitor induced seismicity related to gas storage operations, a seismic network (the Collalto Seismic Network) has been deployed in 2011. The Collalto Seismic Network is composed by 10 broadband stations, deployed within an area of about 20 km x 20 km, and provides high-quality continuous data since January 1st, 2012. In this work we present preliminary results from ambient noise interferometry using a two-months sample of continuous seismic data, i.e. from October 1st, 2012, to the

  6. Localized acoustic surface modes

    NASA Astrophysics Data System (ADS)

    Farhat, Mohamed; Chen, Pai-Yen; Bağcı, Hakan

    2016-04-01

    We introduce the concept of localized acoustic surface modes. We demonstrate that they are induced on a two-dimensional cylindrical rigid surface with subwavelength corrugations under excitation by an incident acoustic plane wave. Our results show that the corrugated rigid surface is acoustically equivalent to a cylindrical scatterer with uniform mass density that can be represented using a Drude-like model. This, indeed, suggests that plasmonic-like acoustic materials can be engineered with potential applications in various areas including sensing, imaging, and cloaking.

  7. Low frequency acoustic microscope

    DOEpatents

    Khuri-Yakub, Butrus T.

    1986-11-04

    A scanning acoustic microscope is disclosed for the detection and location of near surface flaws, inclusions or voids in a solid sample material. A focused beam of acoustic energy is directed at the sample with its focal plane at the subsurface flaw, inclusion or void location. The sample is scanned with the beam. Detected acoustic energy specularly reflected and mode converted at the surface of the sample and acoustic energy reflected by subsurface flaws, inclusions or voids at the focal plane are used for generating an interference signal which is processed and forms a signal indicative of the subsurface flaws, inclusions or voids.

  8. Acoustic dispersive prism.

    PubMed

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  9. Acoustic dispersive prism

    PubMed Central

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz–1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  10. Acoustic dispersive prism

    NASA Astrophysics Data System (ADS)

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium.

  11. Refractive index determination by coherence scanning interferometry.

    PubMed

    Yoshino, H; Kaminski, P M; Smith, R; Walls, J M; Mansfield, D

    2016-05-20

    Coherence scanning interferometry is established as a powerful noncontact, three-dimensional, metrology technique used to determine accurate surface roughness and topography measurements with subnanometer precision. The helical complex field (HCF) function is a topographically defined helix modulated by the electrical field reflectance, originally developed for the measurement of thin films. An approach to extend the capability of the HCF function to determine the spectral refractive index of a substrate or absorbing film has recently been proposed. In this paper, we confirm this new capability, demonstrating it on surfaces of silicon, gold, and a gold/palladium alloy using silica and zirconia oxide thin films. These refractive index dispersion measurements show good agreement with those obtained by spectroscopic ellipsometry. PMID:27411157

  12. Polarization Effects Aboard the Space Interferometry Mission

    NASA Technical Reports Server (NTRS)

    Levin, Jason; Young, Martin; Dubovitsky, Serge; Dorsky, Leonard

    2006-01-01

    For precision displacement measurements, laser metrology is currently one of the most accurate measurements. Often, the measurement is located some distance away from the laser source, and as a result, stringent requirements are placed on the laser delivery system with respect to the state of polarization. Such is the case with the fiber distribution assembly (FDA) that is slated to fly aboard the Space Interferometry Mission (SIM) next decade. This system utilizes a concatenated array of couplers, polarizers and lengthy runs of polarization-maintaining (PM) fiber to distribute linearly-polarized light from a single laser to fourteen different optical metrology measurement points throughout the spacecraft. Optical power fluctuations at the point of measurement can be traced back to the polarization extinction ration (PER) of the concatenated components, in conjunction with the rate of change in phase difference of the light along the slow and fast axes of the PM fiber.

  13. Observations of Circumstellar Disks with Infrared Interferometry

    NASA Technical Reports Server (NTRS)

    Akeson, Rachel

    2008-01-01

    Star formation is arguably the area of astrophysics in which infrared interferometry has had the biggest impact. The optically thick portion of T Tauri and Herbig Ae/Be disks DO NOT extend to a few stellar radii of the stellar surface. Emission is coming from near the dust sublimation radius, but not all from a single radius. The Herbig Ae stars can be either flared or self-shadowed but very massive (early Be) stars are geometrically thin. The Herbig Ae stars can be either flared or self-shadowed but very massive (early Be) stars are geometrically thin. Observational prospects are rapidly improving: a) Higher spectral resolution will allow observations of the gas: jets, winds, accretion. b) Closure phase and imaging will help eliminate model uncertainties/dependencies.

  14. Towards experimental demonstration of shaken lattice interferometry

    NASA Astrophysics Data System (ADS)

    Weidner, Carrie; Yu, Hoon; Anderson, Dana

    2016-05-01

    We report on experimental progress towards performing interferometry using atoms trapped in an optical lattice. That is, we load Rb-87 atoms into the ground state of a red-detuned optical lattice potential V(x) =V0cos [ 2 kx + ϕ(t) ] . By changing ϕ(t) , we wish to implement the standard interferometric sequence of beam splitting, propagation, reflection, reverse propagation, and recombination. In order to find the desired ϕ(t) , we implement a closed-loop learning algorithm which provides a guess for ϕ(t) , analyzes experimental data, then modifies the guess in order to converge upon an optimal shaking function that results in transformation of the initial wavefunction to the desired atomic state. For example, splitting of the atom wavefunction, with equal populations of atoms in the +/- 2 ℏk momentum states may be implemented. The experimental implementation of such a system is described and progress towards the full interferometric sequence is detailed.

  15. Shell deformation studies using holographic interferometry

    NASA Technical Reports Server (NTRS)

    Parmerter, R. R.

    1974-01-01

    The buckling of shallow spherical shells under pressure has been the subject of many theoretical and experimental papers. Experimental data above the theoretical buckling load of Huang have given rise to speculation that shallow shell theory may not adequately predict the stability of nonsymmetric modes in higher-rise shells which are normally classified as shallow by the Reissner criterion. This article considers holographic interferometry as a noncontact, high-resolution method of measuring prebuckling deformations. Prebuckling deformations of a lambda = 9, h/b = 0.038 shell are Fourier-analyzed. Buckling is found to occur in an N = 5 mode as predicted by Huang's theory. The N = 4 mode was unusually stable, suggesting that even at this low value of h/b, stabilizing effects may be at work.

  16. Speckle interferometry of asteroids. I - 433 Eros

    NASA Technical Reports Server (NTRS)

    Drummond, J. D.; Cocke, W. J.; Hege, E. K.; Strittmatter, P. A.; Lambert, J. V.

    1985-01-01

    Analytical expressions are derived for the semimajor and semiminor axes and orientation angle of the ellipse projected by a triaxial asteroid, and the results are applied speckle-interferometry observations of the 433 Eros asteroid. The expressions were calculated as functions of the dimensions and pole of the body and of the asterocentric position of the earth and the sun. On the basis of the analytical expressions, the dimensions of 433 Eros are obtained. The light curve from December 18, 1981 is compared to the dimensions to obtain a geometric albedo of 0.156 (+ or - 0.010). A series of two-dimensional power spectra and autocorrelation functions for 433 Eros show that it is spinning in space.

  17. Sagnac Interferometry with a Single Atomic Clock.

    PubMed

    Stevenson, R; Hush, M R; Bishop, T; Lesanovsky, I; Fernholz, T

    2015-10-16

    The Sagnac effect enables interferometric measurements of rotation with high precision. Using matter waves instead of light promises resolution enhancement by orders of magnitude that scales with particle mass. So far, the paradigm for matter wave Sagnac interferometry relies on de Broglie waves and thus on free propagation of atoms either in free fall or within waveguides. However, the Sagnac effect can be expressed as a proper time difference experienced by two observers moving in opposite directions along closed paths and has indeed been measured with atomic clocks flown around Earth. Inspired by this, we investigate an interferometer comprised of a single atomic clock. The Sagnac effect manifests as a phase shift between trapped atoms in different internal states after transportation along closed paths in opposite directions, without any free propagation. With analytic models, we quantify limitations of the scheme arising from atomic dynamics and finite temperature. Furthermore, we suggest an implementation with previously demonstrated technology. PMID:26550871

  18. Optics and interferometry with atoms and molecules

    SciTech Connect

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

    2009-07-15

    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 the basic tools for coherent atom optics are described including diffraction by nanostructures and laser light, three-grating interferometers, and double wells on atom chips. Scientific advances in a broad range of fields that have resulted from the application of atom interferometers are reviewed. These are grouped in three categories: (i) fundamental quantum science, (ii) precision metrology, and (iii) 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.

  19. Confocal simultaneous phase-shifting interferometry

    SciTech Connect

    Zhao Chenguang; Tan Jiubin; Tang Jianbo; Liu Tao; Liu Jian

    2011-02-10

    In order to implement the ultraprecise measurement with large range and long working distance in confocal microscopy, confocal simultaneous phase-shifting interferometry (C-SPSI) has been presented. Four channel interference signals, with {pi}/2 phase shift between each other, are detected simultaneously in C-SPSI. The actual surface height is then calculated by combining the optical sectioning with the phase unwrapping in the main cycle of the interference phase response, and the main cycle is determined using the bipolar property of differential confocal microscopy. Experimental results showed that 1 nm of axial depth resolution was achieved for either low- or high-NA objective lenses. The reflectivity disturbance resistibility of C-SPSI was demonstrated by imaging a typical microcircuit specimen. C-SPSI breaks through the restriction of low NA on the axial depth resolution of confocal microscopy effectively.

  20. Sagnac Interferometry with a Single Atomic Clock

    NASA Astrophysics Data System (ADS)

    Stevenson, R.; Hush, M. R.; Bishop, T.; Lesanovsky, I.; Fernholz, T.

    2015-10-01

    The Sagnac effect enables interferometric measurements of rotation with high precision. Using matter waves instead of light promises resolution enhancement by orders of magnitude that scales with particle mass. So far, the paradigm for matter wave Sagnac interferometry relies on de Broglie waves and thus on free propagation of atoms either in free fall or within waveguides. However, the Sagnac effect can be expressed as a proper time difference experienced by two observers moving in opposite directions along closed paths and has indeed been measured with atomic clocks flown around Earth. Inspired by this, we investigate an interferometer comprised of a single atomic clock. The Sagnac effect manifests as a phase shift between trapped atoms in different internal states after transportation along closed paths in opposite directions, without any free propagation. With analytic models, we quantify limitations of the scheme arising from atomic dynamics and finite temperature. Furthermore, we suggest an implementation with previously demonstrated technology.

  1. Testing General Relativity with Atom Interferometry

    SciTech Connect

    Dimopoulos, Savas; Graham, Peter W.; Hogan, Jason M.; Kasevich, Mark A.

    2007-03-16

    The unprecedented precision of atom interferometry will soon lead to laboratory tests of general relativity to levels that will rival or exceed those reached by astrophysical observations. We propose such an experiment that will initially test the equivalence principle to 1 part in 10{sup 15} (300 times better than the current limit), and 1 part in 10{sup 17} in the future. It will also probe general relativistic effects--such as the nonlinear three-graviton coupling, the gravity of an atom's kinetic energy, and the falling of light--to several decimals. In contrast with astrophysical observations, laboratory tests can isolate these effects via their different functional dependence on experimental variables.

  2. Testing general relativity with atom interferometry.

    PubMed

    Dimopoulos, Savas; Graham, Peter W; Hogan, Jason M; Kasevich, Mark A

    2007-03-16

    The unprecedented precision of atom interferometry will soon lead to laboratory tests of general relativity to levels that will rival or exceed those reached by astrophysical observations. We propose such an experiment that will initially test the equivalence principle to 1 part in 10(15) (300 times better than the current limit), and 1 part in 10(17) in the future. It will also probe general relativistic effects - such as the nonlinear three-graviton coupling, the gravity of an atom's kinetic energy, and the falling of light - to several decimals. In contrast with astrophysical observations, laboratory tests can isolate these effects via their different functional dependence on experimental variables. PMID:17501039

  3. Apparatus for Ultra-Cold Fermion Interferometry

    NASA Astrophysics Data System (ADS)

    Aubin, Seth; Garcia, Aiyana; Desalvo, Brian

    2008-05-01

    We present progress on the construction of an apparatus for ultra-cold fermion interferometry experiments. The apparatus consists of two connected glass vacuum cells: Fermionic potassium (^40K) and bosonic rubidium (^87Rb) atoms are cooled and collected in a dual-species magneto-optical trap (MOT) in the first cell and are then transported magnetically to the second cell, where they are loaded into a micro-magnetic chip trap. We use radio-frequency (RF) evaporation to cool the rubidium atoms, which in turn sympathetically cool the potassium atoms. The apparatus takes advantage of the rapid cooling inherent to micro-magnetic traps, while also benefiting from the ultra high vacuum achievable with a two chamber vacuum system. In describing our experimental approach, we address the experimental challenges and possible force-sensing applications of fermion interferometers on chips.

  4. Radio-frequency low-coherence interferometry.

    PubMed

    Fernández-Pousa, Carlos R; Mora, José; Maestre, Haroldo; Corral, Pablo

    2014-06-15

    A method for retrieving low-coherence interferograms, based on the use of a microwave photonics filter, is proposed and demonstrated. The method is equivalent to the double-interferometer technique, with the scanning interferometer replaced by an analog fiber-optics link and the visibility recorded as the amplitude of its radio-frequency (RF) response. As a low-coherence interferometry system, it shows a decrease of resolution induced by the fiber's third-order dispersion (β3). As a displacement sensor, it provides highly linear and slope-scalable readouts of the interferometer's optical path difference in terms of RF, even in the presence of third-order dispersion. In a proof-of-concept experiment, we demonstrate 20-μm displacement readouts using C-band EDFA sources and standard single-mode fiber. PMID:24978555

  5. Ultrafast electrooptic dual-comb interferometry.

    PubMed

    Durán, Vicente; Tainta, Santiago; Torres-Company, Victor

    2015-11-16

    Dual-comb interferometry is a particularly compelling technique that relies on the phase coherence of two laser frequency combs for measuring broadband complex spectra. This method is rapidly advancing the field of optical spectroscopy and empowering new applications, from nonlinear microscopy to laser ranging. Up to now, most dual-comb interferometers were based on modelocked lasers, whose repetition rates have restricted the measurement speed to ~kHz. Here we demonstrate a dual-comb interferometer that is based on electrooptic frequency combs and measures consecutive complex spectra at an ultra-high refresh rate of 25 MHz. These results pave the way for novel scientific and metrology applications of frequency comb generators beyond the realm of molecular spectroscopy, where the measurement of ultrabroadband waveforms is of paramount relevance. PMID:26698533

  6. Nanoscale defect detection by heterodyne interferometry

    SciTech Connect

    Lin Haoshan; Li Yuhe; Wang Dongsheng; Tong Xiaolei; Liu Mei

    2009-03-10

    We construct an instrument that facilitates the measurement of nanoscale defects. It is based on heterodyne interferometry with phase measurement that utilizes a polarizing beam splitter to form a measuring signal and an oscillating cantilever tip that acts as a scanning probe to get the measurement values of sample topography. The dependence of the tip displacement on the variation of tip-sample distance and the comb scanning of the sample topography are investigated by experiments. The results prove that the tip displacement increases and is enough to be discriminated in various positions where the sample is approached. The system has been successfully utilized to measure the defect characterization by measuring the pitch of the standard sample. The results also show that the heterodyne system has good repeatability, a large measurement range, and high accuracy, with a measurement stability of 0.5 nm.

  7. Low Coherence Interferometry in Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Neef, A.; Seyda, V.; Herzog, D.; Emmelmann, C.; Schönleber, M.; Kogel-Hollacher, M.

    Selective Laser Melting (SLM) is an additive layer manufacturing technology that offers several advantages compared to conven- tional methods of production such as an increased freedom of design and a toolless production suited for variable lot sizes. Despite these attractive aspects today's state of the art SLM machines lack a holistic process monitoring system that detects and records typical defects during production. A novel sensor concept based on the low coherence interferometry (LCI) was integrated into an SLM production setup. The sensor is mounted coaxially to the processing laser beam and is capable of sampling distances along the optical axis. Measurements during and between the processing of powder layers can reveal crucial topology information which is closely related to the final part quality. The overall potential of the sensor in terms of quality assurance and process control is being discussed. Furthermore fundamental experiments were performed to derive the performance of the system.

  8. Molecular wave packet interferometry and quantum entanglement

    NASA Astrophysics Data System (ADS)

    Martínez-Galicia, Ricardo; Romero-Rochín, Víctor

    2005-03-01

    We study wave packet interferometry (WPI) considering the laser pulse fields both classical and quantum mechanically. WPI occurs in a molecule after subjecting it to the interaction with a sequence of phase-locked ultrashort laser pulses. Typically, the measured quantity is the fluorescence of the molecule from an excited electronic state. This signal has imprinted the interference of the vibrational wave packets prepared by the different laser pulses of the sequence. The consideration of the pulses as quantum entities in the analysis allows us to study the entanglement of the laser pulse states with the molecular states. With a simple model for the molecular system, plus several justified approximations, we solve for the fully quantum mechanical molecule-electromagnetic field state. We then study the reduced density matrices of the molecule and the laser pulses separately. We calculate measurable corrections to the case where the fields are treated classically.

  9. Externally Dispersed Interferometry for Precision Radial Velocimetry

    SciTech Connect

    Erskine, D J; Muterspaugh, M W; Edelstein, J; Lloyd, J; Herter, T; Feuerstein, W M; Muirhead, P; Wishnow, E

    2007-03-27

    Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic spectral comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. The moire pattern shifts in phase in response to a Doppler shift. Moire patterns are broader than the underlying spectral features and more easily survive spectrograph blurring and common distortions. Thus, the EDI technique allows lower resolution spectrographs having relaxed optical tolerances (and therefore higher throughput) to return high precision velocity measurements, which otherwise would be imprecise for the spectrograph alone.

  10. Nulling interferometry without achromatic phase shifters.

    PubMed

    Mieremet, Arjan L; Braat, Joseph J M

    2002-08-01

    In the infrared wavelength region, a typical star is approximately a million times brighter than the planet that surrounds it, which is a major problem when we attempt to detect exoplanets in a direct manner. Nulling interferometry is a technique that one can use to solve this problem by attenuating the stellar light and enhancing that of the planet. Generally, deep nulling is achieved by use of achromatic phase shifters (APSs). Unfortunately, the technology needed to build these APSs is not yet fully developed. We show that deep nulling can also be achieved by using delay lines only. We investigate the nulling depth as a function of the width of the wavelength interval and the number of telescopes. We also show that we can obtain nulling depths of less than 10(-6), which are required for exoplanet detection. Furthermore, we investigate the properties of the transmission map and make a comparison between our system and an APS system. PMID:12153105

  11. Moire interferometry for thermal expansion of composites

    NASA Technical Reports Server (NTRS)

    Bowles, D. E.; Tenney, D. R.; Post, D.; Herakovich, C. T.

    1982-01-01

    Moire interferometry by reflection is described and demonstrated for the case of a real reference grating of 1200 lines/mm. Extraneous beams can be displaced and stopped by using a wedge-shaped air gap between reference and specimen gratings. Double-order dominance, the use of diffraction sequences for reflection, the isolation of preferred sequences, and the use of two-beam interference are discussed. Experimental accuracy is enhanced significantly by using several data points to establish displacements along a line, and random errors characterized by one standard deviation can be as small as one microstrain. The method is well adapted to thermal environments, coefficients of thermal expansion of selected graphite-epoxy laminates being determined in the temperature range of 297-422 K. Very good precision was achieved for a wide range of thermal expansion coefficients, from approximately zero to 27 microstrains/K.

  12. Transonic flow visualization using holographic interferometry

    NASA Technical Reports Server (NTRS)

    Bryanston-Cross, Peter J.

    1987-01-01

    An account is made of some of the applications of holographic interferometry to the visualization of transonic flows. In the case of the compressor shock visualization, the method is used regularly and has moved from being a research department invention to a design test tool. With the implementation of automatic processing and simple digitization systems, holographic vibrational analysis has also moved into routine nondestructive testing. The code verification interferograms were instructive, but the main turbomachinery interest is now in 3 dimensional flows. A major data interpretation effort will be required to compute tomographically the 3 dimensional flow around the leading or the trailing edges of a rotating blade row. The bolt on approach shows the potential application to current unsteady flows of interest. In particular that of the rotor passing and vortex interaction effects is experienced by the new generation of unducted fans. The turbocharger tests presents a new area for the application of holography.

  13. Edge effects in composites by moire interferometry

    NASA Technical Reports Server (NTRS)

    Czarnek, R.; Post, D.; Herakovich, C.

    1983-01-01

    The very high sensitivity of moire interferometry has permitted the present edge effect experiments to be conducted at a low average stress and strain level, assuring linear and elastic behavior in the composite material samples tested. Sensitivity corresponding to 2450 line/mm moire was achieved with a 0.408 micron/fringe. Simultaneous observations of the specimen face and edge displacement fields showed good fringe definition despite the 1-mm thickness of the specimens and the high gradients, and it is noted that the use of a carrier pattern and optical filtering was effective in even these conditions. Edge effects and dramatic displacement gradients were confirmed in angle-ply composite laminates.

  14. Aperture-synthesis interferometry at optical wavelengths

    NASA Technical Reports Server (NTRS)

    Burke, Bernard F.

    1987-01-01

    The prospects for applying aperture-synthesis interferometry to the optical domain are reviewed. The radio examples such as the VLA provide a model, since the concepts are equally valid for radio and optical wavelengths. If scientific problems at the milliarc-second resolution level (or better) are to be addressed, a space-based optical array seems to be the only practical alternative, for the same reasons that dictated array development at radio wavelengths. One concept is examined, and speculations are offered concerning the prospects for developing real systems. Phase-coherence is strongly desired for a practical array, although self-calibration and phase-closure techniques allow one to relax the restriction on absolute phase stability. The design of an array must be guided by the scientific problems to be addressed.

  15. Self-calibrating common-path interferometry.

    PubMed

    Porras-Aguilar, Rosario; Falaggis, Konstantinos; Ramirez-San-Juan, Julio C; Ramos-Garcia, Ruben

    2015-02-01

    A quantitative phase measuring technique is presented that estimates the object phase from a series of phase shifted interferograms that are obtained in a common-path configuration with unknown phase shifts. The derived random phase shifting algorithm for common-path interferometers is based on the Generalized Phase Contrast theory [pl. Opt.40(2), 268 (2001)10.1063/1.1404846], which accounts for the particular image formation and includes effects that are not present in two-beam interferometry. It is shown experimentally that this technique can be used within common-path configurations employing nonlinear liquid crystal materials as self-induced phase filters for quantitative phase imaging without the need of phase shift calibrations. The advantages of such liquid crystal elements compared to spatial light modulator based solutions are given by the cost-effectiveness, self-alignment, and the generation of diminutive dimensions of the phase filter size, giving unique performance advantages. PMID:25836191

  16. Grading of wooden plates for musical instrument making by means of holographic interferometry

    NASA Astrophysics Data System (ADS)

    Urgela, Stanislav

    1998-07-01

    Wood selection for musical instrument making is usually based on visual estimation and on manual mechanical and vibrational subjective testing. The method proposed uses TV holography and holographic interferometry with a double- pulsed laser to visualize the standing acoustic waves and the impact generated by transient waves as inspection testing tools. The theory of bending waves in orthotropic plates is used to interpret the experimental results. This enables us to estimate Young's moduli parallel to and perpendicular to the grain and the in-plane shear modulus in wood. The testing is nondestructive, so the expensive wooden plates can be used in production. Properly modified, the test can be applied to the judgement of any wooden and wooden composite plates. The 3D charts for a set of the physioacoustical characteristics--density, modulus of elasticity, and acoustic constant on the axes--are confirmed as a useful procedure that can help to provide more objective results in wood grading for materials selection in the design of musical instruments, mainly bowed string instruments and pianos.

  17. Interferometry using undulator sources (invited, abstract)

    NASA Astrophysics Data System (ADS)

    Beguiristain, R.; Goldberg, K. A.; Tejnil, E.; Bokor, J.; Medecki, H.; Attwood, D. T.; Jackson, K.

    1996-09-01

    Optical systems for extreme ultraviolet (EUV) lithography need to use optical components with subnanometer surface figure error tolerances to achieve diffraction-limited performance [M.D. Himel, in Soft X-Ray Projection Lithography, A.M. Hawryluk and R.H. Stulen, eds. (OSA, Washington, D.C., 1993), 18, 1089, and D. Attwood et al., Appl. Opt. 32, 7022 (1993)]. Also, multilayer-coated optics require at-wavelength wavefront measurement to characterize phase effects that cannot be measured by conventional optical interferometry. Furthermore, EUV optical systems will additionally require final testing and alignment at the operational wavelength for adjustment and reduction of the cumulative optical surface errors. Therefore, at-wavelength interferometric measurement of EUV optics will be the necessary metrology tool for the successful development of optics for EUV lithography. An EUV point diffraction interferometer (PDI) has been developed at the Center for X-Ray Optics (CXRO) and has been already in operation for a year [K. Goldberg et al., in Extreme Ultra Lithography, D.T. Attwood and F. Zernike, eds. (OSA, Washington, D.C., 1994), K. Goldberg et al., Proc. SPIE 2437, to be published, and K. Goldberg et al., J. Vac. Sci. Technol. B 13, 2923 (1995)] using an undulator radiation source and coherent optics beamline at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. An overview of the PDI interferometer and some EUV wavefront measurements obtained with this instrument will be presented. In addition, future developments planned for EUV interferometry at CXRO towards the measurement of actual EUV lithography optics will be shown.

  18. Ultrafast nonlinear acoustics in crystals and nanostructures

    NASA Astrophysics Data System (ADS)

    van Capel, P. J. S.

    2008-09-01

    This research aims at experimentally monitoring nonlinear generation and propagation of picosecond coherent acoustic strain wave packets in solids. The experiments are performed by ultrafast pump-probe reflectometry and interferometry. At first, nonlinear strain generation in thin nickel and chromium films is characterized. At high pump fluences, the elevated electron and lattice temperatures in the absorption layer significantly modify thermal and mechanical material parameters, thereby increasing the strain amplitude superlinearly. Electron diffusion is suppressed by electron-electron collisions. The results are accurately described by a two-temperature model for fluences up to 80% of the damage threshold, above which nonthermal processes come into play. At room temperature, the high-amplitude strain waves generated in a thin chromium film and launched into the sapphire substrate, transform into an acoustic shock wave within tens of micrometer due to large atomic displacements and the nonparabolic interatomic potential. When lowering the temperature, thermal attenuation gradually decreases and lattice dispersion comes into play. At 20 K, propagation is undamped, thus leading to the formation of acoustic solitons. A maximum number of seven solitons is measured. By performing measurements on different sample thicknesses, the superlinear soliton velocity can be determined. Since the soliton velocity is intimately linked to its spatial width, a soliton width as short as two nanometer can be derived. The measured soliton velocities and volumes are in excellent agreement with numerical simulations of propagation, as well with the exact predictions by the Korteweg - De Vries equation. Following the demonstration of acoustic solitons, an experiment was devised in which these solitons are used to modulate nanostructures on ultrafast timescales. Modulation of exciton states inside a semiconductor within times shorter than the exciton lifetime leads to chirping, i

  19. Determination of thin hydrodynamic lubricating film thickness using dichromatic interferometry.

    PubMed

    Guo, L; Wong, P L; Guo, F; Liu, H C

    2014-09-10

    This paper introduces the application of dichromatic interferometry for the study of hydrodynamic lubrication. In conventional methods, two beams with different colors are projected consecutively on a static object. By contrast, the current method deals with hydrodynamic lubricated contacts under running conditions and two lasers with different colors are projected simultaneously to form interference images. Dichromatic interferometry incorporates the advantages of monochromatic and chromatic interferometry, which are widely used in lubrication research. This new approach was evaluated statically and dynamically by measuring the inclination of static wedge films and the thickness of the hydrodynamic lubricating film under running conditions, respectively. Results show that dichromatic interferometry can facilitate real-time determination of lubricating film thickness and is well suited for the study of transient or dynamic lubricating problems. PMID:25321689

  20. Full-Field Imaging of GHz Film Bulk Acoustic Resonator Motion

    SciTech Connect

    Telschow, Kenneth Louis; Deason, Vance Albert; Cottle, David Lynn; Larson III, J. D.

    2003-10-01

    A full-field view laser ultrasonic imaging method has been developed that measures acoustic motion at a surface without scanning. Images are recorded at normal video frame rates by using dynamic holography with photorefractive interferometric detection. By extending the approach to ultra high frequencies, an acoustic microscope has been developed that is capable of operation at gigahertz frequency and micron length scales. Both acoustic amplitude and phase are recorded, allowing full calibration and determination of phases to within a single arbitrary constant. Results are presented of measurements at frequencies of 800-900 MHz, illustrating a multitude of normal mode behavior in electrically driven thin film acoustic resonators. Coupled with microwave electrical impedance measurements, this imaging mode provides an exceptionally fast method for evaluation of electric-to-acoustic coupling of these devices and their performance. Images of 256 /spl times/ 240 pixels are recorded at 18 fps rates synchronized to obtain both in-phase and quadrature detection of the acoustic motion. Simple averaging provides sensitivity to the subnanometer level at each pixel calibrated over the image using interferometry. Identification of specific acoustic modes and their relationship to electrical impedance characteristics show the advantages and overall high speed of the technique.

  1. Wedge Prism for Direction Resolved Speckle Correlation Interferometry

    SciTech Connect

    Pechersky, M.J.

    1999-01-20

    The role of a wedge prism for strain sign determination and enhancing the sensitivity for sub-fringe changes is emphasized. The design and incorporation aspects for in-plane sensitive interferometers have been described in detail. Some experimental results dealing with stress determination by laser annealing and speckle corelation interferometry are presented. The prism can also be applied to produce standardized carrier fringes in spatial phase shifting interferometry.

  2. Wedge prism for direction resolved speckle correlation interferometry

    SciTech Connect

    Vikram, C.S.; Pechersky, M.J.

    1999-10-01

    The role of a wedge prism for strain sign determination and to enhance the sensitivity for subfringe changes is presented. The design and incorporation aspects for in-plane sensitive interferometers are described in detail. Some experimental results dealing with stress determination by laser annealing and speckle correlation interferometry are presented. The prism can also be applied to produce standardized carrier fringes in spatial phase shifting interferometry. {copyright} {ital 1999 Society of Photo-Optical Instrumentation Engineers.}

  3. A Possible Future for Space-Based Interferometry

    NASA Technical Reports Server (NTRS)

    Labadie, L.; Leger, A.; Malbet, F.; Danchi, William C.; Lopez, B.

    2013-01-01

    We address the question of space interferometry following the recent outcome of the science themes selection by ESA for the L2/L3 missions slots. We review the current context of exoplanetary sciences and its impact for an interferometric mission. We argue that space interferometry will make a major step forward when the scientific communities interested in this technique will merge their efforts into a coherent technology development plan.

  4. Resolving The Sky - Radio Interferometry: Past, Present and Future

    NASA Astrophysics Data System (ADS)

    For more than half a century, radio interferometry has revolutionised our view of the Universe. New phenomena, such as relativistic motion in AGN have been discovered, and a wealth of detail has been revealed about a wide variety of astronomical sources, from nearby stars to the most distant galaxies. These discoveries have been enabled by radio interferometry's routine capability to deliver images with sub-milliarcsecond resolution and micro-arcsecond precision astrometry. Major new advances in both the interferometric technique and the science it delivers are expected over the coming decade. This conference will take a look at the past, present and future of radio interferometry, as the astronomical community prepares for the next big step forward, the Square Kilometre Array (SKA). The meeting coincides with the retirement of Prof. Richard T. Schilizzi, Director of the SKA Project Development Office (SPDO) and past director of the Joint Institute for VLBI in Europe (JIVE). We celebrate the major contribution Richard has made to the field with a scientific programme that will address the following topics: key historical developments in interferometry, the study of micro-quasars and AGN, the development of advanced interferometry techniques and new calibration algorithms, future interferometers (incl. ALMA, SKA and the SKA pathfinders & precursors), mm and sub-mm interferometry, precision spacecraft navigation, geodetic VLBI and Space VLBI.

  5. Acoustics Critical Readiness Review

    NASA Technical Reports Server (NTRS)

    Ballard, Kenny

    2010-01-01

    This presentation reviews the status of the acoustic equipment from the medical operations perspective. Included is information about the acoustic dosimeters, sound level meter, and headphones that are planned for use while on orbit. Finally there is information about on-orbit hearing assessments.

  6. The challenge of acoustics

    NASA Astrophysics Data System (ADS)

    Lord, P.

    1981-01-01

    The various applications of acoustics, including sonar, ultrasonic examination of unborn foetuses and architectural applications, are briefly reviewed. Problems in traffic and industrial noise, auditorium design and explosive noise are considered in more detail. The educational aspects of acoustical science and technology are briefly considered.

  7. Highly directional acoustic receivers.

    PubMed

    Cray, Benjamin A; Evora, Victor M; Nuttall, Albert H

    2003-03-01

    The theoretical directivity of a single combined acoustic receiver, a device that can measure many quantities of an acoustic field at a collocated point, is presented here. The formulation is developed using a Taylor series expansion of acoustic pressure about the origin of a Cartesian coordinate system. For example, the quantities measured by a second-order combined receiver, denoted a dyadic sensor, are acoustic pressure, the three orthogonal components of acoustic particle velocity, and the nine spatial gradients of the velocity vector. The power series expansion, which can be of any order, is cast into an expression that defines the directivity of a single receiving element. It is shown that a single highly directional dyadic sensor can have a directivity index of up to 9.5 dB. However, there is a price to pay with highly directive sensors; these sensors can be significantly more sensitive to nonacoustic noise sources. PMID:12656387

  8. Ocean acoustic hurricane classification.

    PubMed

    Wilson, Joshua D; Makris, Nicholas C

    2006-01-01

    Theoretical and empirical evidence are combined to show that underwater acoustic sensing techniques may be valuable for measuring the wind speed and determining the destructive power of a hurricane. This is done by first developing a model for the acoustic intensity and mutual intensity in an ocean waveguide due to a hurricane and then determining the relationship between local wind speed and underwater acoustic intensity. From this it is shown that it should be feasible to accurately measure the local wind speed and classify the destructive power of a hurricane if its eye wall passes directly over a single underwater acoustic sensor. The potential advantages and disadvantages of the proposed acoustic method are weighed against those of currently employed techniques. PMID:16454274

  9. Acoustic Remote Sensing

    NASA Astrophysics Data System (ADS)

    Dowling, David R.; Sabra, Karim G.

    2015-01-01

    Acoustic waves carry information about their source and collect information about their environment as they propagate. This article reviews how these information-carrying and -collecting features of acoustic waves that travel through fluids can be exploited for remote sensing. In nearly all cases, modern acoustic remote sensing involves array-recorded sounds and array signal processing to recover multidimensional results. The application realm for acoustic remote sensing spans an impressive range of signal frequencies (10-2 to 107 Hz) and distances (10-2 to 107 m) and involves biomedical ultrasound imaging, nondestructive evaluation, oil and gas exploration, military systems, and Nuclear Test Ban Treaty monitoring. In the past two decades, approaches have been developed to robustly localize remote sources; remove noise and multipath distortion from recorded signals; and determine the acoustic characteristics of the environment through which the sound waves have traveled, even when the recorded sounds originate from uncooperative sources or are merely ambient noise.

  10. Acoustic integrated extinction

    PubMed Central

    Norris, Andrew N.

    2015-01-01

    The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122, 3206–3210. (doi:10.1121/1.2801546)) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we derive a formula for the acoustic IE that is valid for causal and non-causal scattering. The general result is expressed as an integral of the time-dependent forward scattering function. The IE reduces to a finite integral for scatterers with zero long-wavelength monopole and dipole amplitudes. Implications for acoustic cloaking are discussed and a new metric is proposed for broadband acoustic transparency. PMID:27547100

  11. Virtual acoustics displays

    NASA Technical Reports Server (NTRS)

    Wenzel, Elizabeth M.; Fisher, Scott S.; Stone, Philip K.; Foster, Scott H.

    1991-01-01

    The real time acoustic display capabilities are described which were developed for the Virtual Environment Workstation (VIEW) Project at NASA-Ames. The acoustic display is capable of generating localized acoustic cues in real time over headphones. An auditory symbology, a related collection of representational auditory 'objects' or 'icons', can be designed using ACE (Auditory Cue Editor), which links both discrete and continuously varying acoustic parameters with information or events in the display. During a given display scenario, the symbology can be dynamically coordinated in real time with 3-D visual objects, speech, and gestural displays. The types of displays feasible with the system range from simple warnings and alarms to the acoustic representation of multidimensional data or events.

  12. Cochlear bionic acoustic metamaterials

    NASA Astrophysics Data System (ADS)

    Ma, Fuyin; Wu, Jiu Hui; Huang, Meng; Fu, Gang; Bai, Changan

    2014-11-01

    A design of bionic acoustic metamaterial and acoustic functional devices was proposed by employing the mammalian cochlear as a prototype. First, combined with the experimental data in previous literatures, it is pointed out that the cochlear hair cells and stereocilia cluster are a kind of natural biological acoustic metamaterials with the negative stiffness characteristics. Then, to design the acoustic functional devices conveniently in engineering application, a simplified parametric helical structure was proposed to replace actual irregular cochlea for bionic design, and based on the computational results of such a bionic parametric helical structure, it is suggested that the overall cochlear is a local resonant system with the negative dynamic effective mass characteristics. There are many potential applications in the bandboard energy recovery device, cochlear implant, and acoustic black hole.

  13. Surface acoustic BLOCH oscillations, the Wannier-Stark ladder, and Landau-Zener tunneling in a solid.

    PubMed

    de Lima, M M; Kosevich, Yu A; Santos, P V; Cantarero, A

    2010-04-23

    We present the experimental observation of Bloch oscillations, the Wannier-Stark ladder, and Landau-Zener tunneling of surface acoustic waves in perturbed grating structures on a solid substrate. A model providing a quantitative description of our experimental observations, including multiple Landau-Zener transitions of the anticrossed surface acoustic Wannier-Stark states, is developed. The use of a planar geometry for the realization of the Bloch oscillations and Landau-Zener tunneling allows a direct access to the elastic field distribution. The vertical surface displacement has been measured by interferometry. PMID:20482064

  14. Ocean seismo-acoustics. Low-frequency underwater acoustics

    SciTech Connect

    Akal, T.; berkson, J.M.

    1986-01-01

    This book presents information on seismo-acoustic propagation in seawater and sea beds that includes theoretical developments, modelling and experiments, and fluctuations. Boundary scatteiring, seismo-acoustic waves and seismo-acoustic noise are discussed. Technology and new approaches in seismo-acoustic measurements are presented.

  15. Evaluation of Homogeneity and Elastic Properties of Solid Argon at High Pressures Using Picosecond Laser Ultrasonic Interferometry

    NASA Astrophysics Data System (ADS)

    Zerr, A.; Kuriakose, M.; Raetz, S.; Chigarev, N.; Nikitin, S. M.; Gasteau, D.; Tournat, V.; Bulou, A.; Castagnede, B.; Gusev, V. E.; Lomonosov, A.

    2015-12-01

    In picosecond ultrasonic interferometry [1], femto- or picosecond pump laser pulses are first used to generate acoustic pulses ranging from several to a few tens of nanometres length, thanks to the optoacoustic transduction in a light absorbing generator. Time-delayed femto- or picosecond probe laser pulses are then used to follow the propagation of these ultrashort acoustic pulses through a transparent medium that is in contact with the generator surface. The transient signal thus contains, at each moment in time, information on the local elastic, optical and elasto-optical properties of the tested material at the position where the laser-generated picosecond acoustic pulse is located during its propagation in the sample depth. Hence, the technique allows evaluation of sound velocities and elastic anisotropy of micro-crystallites composing a transparent material compressed to high pressures in a diamond anvil cell (DAC). This interferometry technique also helps to understand the micro-crystallite orientations in a case of elastically anisotropic material. Here we report the preliminary results of picosecond ultrasonic interferometry applied to the evaluation of homogeneities and elastic properties of polycrystalline solid argon compressed to 10 GPa and 15 GPa. In comparison with the earlier reported experiments on H2O ice at Mbar pressures [2], more efforts were spent to the evaluation of the lateral microstructure of the sample at high pressures, i.e., to inhomogeneities along the surface of the optoacoustic generator, rather than to the in-depth imaging along the axis of the DAC. The lateral imaging is performed over a distance of 60 - 90 µm, nearly corresponding to the complete sample diameter. In addition to the presence of expected lateral inhomogeneities the obtained results demonstrate important changes in their distribution upon pressure increase from 10 to 15 GPa. On the basis of the analysis of the statistic probability in the detection of differently

  16. Acoustic cooling engine

    DOEpatents

    Hofler, Thomas J.; Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1988-01-01

    An acoustic cooling engine with improved thermal performance and reduced internal losses comprises a compressible fluid contained in a resonant pressure vessel. The fluid has a substantial thermal expansion coefficient and is capable of supporting an acoustic standing wave. A thermodynamic element has first and second ends and is located in the resonant pressure vessel in thermal communication with the fluid. The thermal response of the thermodynamic element to the acoustic standing wave pumps heat from the second end to the first end. The thermodynamic element permits substantial flow of the fluid through the thermodynamic element. An acoustic driver cyclically drives the fluid with an acoustic standing wave. The driver is at a location of maximum acoustic impedance in the resonant pressure vessel and proximate the first end of the thermodynamic element. A hot heat exchanger is adjacent to and in thermal communication with the first end of the thermodynamic element. The hot heat exchanger conducts heat from the first end to portions of the resonant pressure vessel proximate the hot heat exchanger. The hot heat exchanger permits substantial flow of the fluid through the hot heat exchanger. The resonant pressure vessel can include a housing less than one quarter wavelength in length coupled to a reservoir. The housing can include a reduced diameter portion communicating with the reservoir. The frequency of the acoustic driver can be continuously controlled so as to maintain resonance.

  17. Acoustic mapping velocimetry

    NASA Astrophysics Data System (ADS)

    Muste, M.; Baranya, S.; Tsubaki, R.; Kim, D.; Ho, H.; Tsai, H.; Law, D.

    2016-05-01

    Knowledge of sediment dynamics in rivers is of great importance for various practical purposes. Despite its high relevance in riverine environment processes, the monitoring of sediment rates remains a major and challenging task for both suspended and bed load estimation. While the measurement of suspended load is currently an active area of testing with nonintrusive technologies (optical and acoustic), bed load measurement does not mark a similar progress. This paper describes an innovative combination of measurement techniques and analysis protocols that establishes the proof-of-concept for a promising technique, labeled herein Acoustic Mapping Velocimetry (AMV). The technique estimates bed load rates in rivers developing bed forms using a nonintrusive measurements approach. The raw information for AMV is collected with acoustic multibeam technology that in turn provides maps of the bathymetry over longitudinal swaths. As long as the acoustic maps can be acquired relatively quickly and the repetition rate for the mapping is commensurate with the movement of the bed forms, successive acoustic maps capture the progression of the bed form movement. Two-dimensional velocity maps associated with the bed form migration are obtained by implementing algorithms typically used in particle image velocimetry to acoustic maps converted in gray-level images. Furthermore, use of the obtained acoustic and velocity maps in conjunction with analytical formulations (e.g., Exner equation) enables estimation of multidirectional bed load rates over the whole imaged area. This paper presents a validation study of the AMV technique using a set of laboratory experiments.

  18. Some Problems of modern acoustics

    NASA Technical Reports Server (NTRS)

    Stan, A.

    1974-01-01

    The multidisciplinary and interdisciplinary character of acoustics is considered and its scientific, technological, economical and social implications, as well as the role of acoustics in creating new machines and equipment and improving the quality of products are outlined. Research beyond audible frequencies, as well as to extremely high acoustic intensities, which requires the development of a nonlinear acoustics is elaborated.

  19. Acoustic well cleaner

    DOEpatents

    Maki, Jr., Voldi E.; Sharma, Mukul M.

    1997-01-21

    A method and apparatus are disclosed for cleaning the wellbore and the near wellbore region. A sonde is provided which is adapted to be lowered into a borehole and which includes a plurality of acoustic transducers arranged around the sonde. Electrical power provided by a cable is converted to acoustic energy. The high intensity acoustic energy directed to the borehole wall and into the near wellbore region, redissolves or resuspends the material which is reducing the permeability of the formation and/or restricting flow in the wellbore.

  20. Acoustic rotation control

    NASA Technical Reports Server (NTRS)

    Elleman, D. D.; Croonquist, A. P.; Wang, T. G. (Inventor)

    1983-01-01

    A system is described for acoustically controlled rotation of a levitated object, which avoids deformation of a levitated liquid object. Acoustic waves of the same wavelength are directed along perpendicular directions across the object, and with the relative phases of the acoustic waves repeatedly switched so that one wave alternately leads and lags the other by 90 deg. The amount of torque for rotating the object, and the direction of rotation, are controlled by controlling the proportion of time one wave leads the other and selecting which wave leads the other most of the time.

  1. PRSEUS Acoustic Panel Fabrication

    NASA Technical Reports Server (NTRS)

    Nicolette, Velicki; Yovanof, Nicolette P.; Baraja, Jaime; Mathur, Gopal; Thrash, Patrick; Pickell, Robert

    2011-01-01

    This report describes the development of a novel structural concept, Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS), that addresses the demanding fuselage loading requirements for the Hybrid Wing or Blended Wing Body (BWB) airplane configuration with regards to acoustic response. A PRSEUS panel was designed and fabricated and provided to NASA-LaRC for acoustic response testing in the Structural Acoustics Loads and Transmission (SALT) facility). Preliminary assessments of the sound transmission characteristics of a PRSEUS panel subjected to a representative Hybrid Wing Body (HWB) operating environment were completed for the NASA Environmentally Responsible Aviation (ERA) Program.

  2. Acoustical heat pumping engine

    DOEpatents

    Wheatley, John C.; Swift, Gregory W.; Migliori, Albert

    1983-08-16

    The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium.

  3. Acoustical heat pumping engine

    DOEpatents

    Wheatley, J.C.; Swift, G.W.; Migliori, A.

    1983-08-16

    The disclosure is directed to an acoustical heat pumping engine without moving seals. A tubular housing holds a compressible fluid capable of supporting an acoustical standing wave. An acoustical driver is disposed at one end of the housing and the other end is capped. A second thermodynamic medium is disposed in the housing near to but spaced from the capped end. Heat is pumped along the second thermodynamic medium toward the capped end as a consequence both of the pressure oscillation due to the driver and imperfect thermal contact between the fluid and the second thermodynamic medium. 2 figs.

  4. Advancing differential atom interferometry for space applications

    NASA Astrophysics Data System (ADS)

    Chiow, Sheng-Wey; Williams, Jason; Yu, Nan

    2016-05-01

    Atom interferometer (AI) based sensors exhibit precision and accuracy unattainable with classical sensors, thanks to the inherent stability of atomic properties. Dual atomic sensors operating in a differential mode further extend AI applicability beyond environmental disturbances. Extraction of the phase difference between dual AIs, however, typically introduces uncertainty and systematic in excess of that warranted by each AI's intrinsic noise characteristics, especially in practical applications and real time measurements. In this presentation, we report our efforts in developing practical schemes for reducing noises and enhancing sensitivities in the differential AI measurement implementations. We will describe an active phase extraction method that eliminates the noise overhead and demonstrates a performance boost of a gravity gradiometer by a factor of 3. We will also describe a new long-baseline approach for differential AI measurements in a laser ranging assisted AI configuration. The approach uses well-developed AIs for local measurements but leverage the mature schemes of space laser interferometry for LISA and GRACE. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a Contract with NASA.

  5. A spectroscopic refractometer based on plasmonic interferometry

    NASA Astrophysics Data System (ADS)

    Feng, Jing; Pacifici, Domenico

    2016-02-01

    We describe the design, fabrication, and testing of a spectroscopic refractometer that employs plasmonic interferometry to measure the optical dielectric functions of materials in the visible range. The proposed device, dubbed a plasmonic refractometer, consists of an array of slit-groove plasmonic interferometers etched in a ˜300 nm-thick metal film (silver or gold) with arm lengths varying in steps of 25 nm up to ˜8 μm. The nano-groove in each interferometer is able to generate propagating surface plasmon polaritons efficiently in a broad wavelength range, without requiring prism- or grating-coupling configurations. An integrated microfluidic channel ensures uniform delivery of dielectric materials in liquid phase. Spectrally resolved plasmonic interferograms are generated by measuring light transmission spectra through the slit of each slit-groove plasmonic interferometer and plotting the normalized intensity as a function of arm length (0.26-8.16 μm) and incident wavelength (400-800 nm) for various combinations of metal/dielectric materials. Fits of the plasmonic interferograms with a surface plasmon interference model allow determination of the refractive index dispersion of a broad class of dielectric materials, over a wide range of wavelengths and dielectric constants. As proof of concept, we extract and report the dielectric functions of representative materials, such as silver, gold, water, methanol, and ethanol.

  6. Glaciological Applications of Terrestrial Radar Interferometry

    NASA Astrophysics Data System (ADS)

    Voytenko, D.; Dixon, T. H.

    2014-12-01

    Terrestrial Radar Interferometry (TRI) is a relatively new ground-based technique that combines the precision and spatial resolution of InSAR with the temporal resolution of GPS. Although TRI can be applied to a variety of fields including bridge and landslide monitoring, it is ideal for studies of the highly dynamic terminal zones of marine-terminating glaciers. Our TRI instrument is the Gamma Portable Radar Interferometer, which operates at 17.2 GHz (1.74 cm wavelength), has two receiving antennas for DEM generation, and generates amplitude and phase images at minute-scale sampling rates. Here we review preliminary results from Breiðamerkurjökull in Iceland and Helheim and Jakobshavn in Greenland. We show that the high sampling rate of the TRI can be used to observe velocity variations at the glacier terminus associated with calving, and the spatial distribution of tidal forcing. Velocity uncertainties, mainly due to atmospheric effects, are typically less than 0.05 m/d. Additionally, iceberg tracking using the amplitude imagery may provide insight into ocean currents near the terminus when fjord or lagoon conditions permit.

  7. Experimental demonstration of deep frequency modulation interferometry.

    PubMed

    Isleif, Katharina-Sophie; Gerberding, Oliver; Schwarze, Thomas S; Mehmet, Moritz; Heinzel, Gerhard; Cervantes, Felipe Guzmán

    2016-01-25

    Experiments for space and ground-based gravitational wave detectors often require a large dynamic range interferometric position readout of test masses with 1 pm/√Hz precision over long time scales. Heterodyne interferometer schemes that achieve such precisions are available, but they require complex optical set-ups, limiting their scalability for multiple channels. This article presents the first experimental results on deep frequency modulation interferometry, a new technique that combines sinusoidal laser frequency modulation in unequal arm length interferometers with a non-linear fit algorithm. We have tested the technique in a Michelson and a Mach-Zehnder Interferometer topology, respectively, demonstrated continuous phase tracking of a moving mirror and achieved a performance equivalent to a displacement sensitivity of 250 pm/Hz at 1 mHz between the phase measurements of two photodetectors monitoring the same optical signal. By performing time series fitting of the extracted interference signals, we measured that the linearity of the laser frequency modulation is on the order of 2% for the laser source used. PMID:26832546

  8. General relativistic effects in atom interferometry

    SciTech Connect

    Dimopoulos, Savas; Hogan, Jason M.; Kasevich, Mark A.; Graham, Peter W.

    2008-08-15

    Atom interferometry is now reaching sufficient precision to motivate laboratory tests of general relativity. We begin by explaining the nonrelativistic calculation of the phase shift in an atom interferometer and deriving its range of validity. From this, we develop a method for calculating the phase shift in general relativity. Both the atoms and the light are treated relativistically and all coordinate dependencies are removed, thus revealing novel terms, cancellations, and new origins for previously calculated terms. This formalism is then used to find the relativistic effects in an atom interferometer in a weak gravitational field for application to laboratory tests of general relativity. The potentially testable relativistic effects include the nonlinear three-graviton coupling, the gravity of kinetic energy, and the falling of light. We propose specific experiments, one currently under construction, to measure each of these effects. These experiments could provide a test of the principle of equivalence to 1 part in 10{sup 15} (300 times better than the present limit), and general relativity at the 10% level, with many potential future improvements. We also consider applications to other metrics including the Lense-Thirring effect, the expansion of the Universe, and preferred frame and location effects.

  9. Quantum Phenomena Tested By Neutron Interferometry

    SciTech Connect

    Rauch, Helmut

    2005-02-15

    Entanglement of two photons, or atoms is a complementary situation to a double slit situation of a single photon, neutron or atom. With neutrons single particle interference phenomena can be observed and the 'entanglement of degrees of freedom', i.e. contextuality can be verified. In this respect, neutrons are proper tools for testing quantum mechanics because they are massive, they couple to electromagnetic fields due to their magnetic moment and they are subject to all basic interactions, and they are sensitive to topological effects, as well. Related experiments will be discussed. Deterministic and stochastic partial absorption experiments can be described by Bell-type inequalities. Recent neutron interferometry experiments based on postselection methods renewed the discussion about quantum nonlocality and the quantum measuring process. It has been shown that interference phenomena can be revived even when the overall interference pattern has lost its contrast. This indicates a persisting coupling in phase space even in cases of spatially separated Schroedinger cat-like situations. These states are extremely fragile and sensitive against any kind of fluctuations and other decoherence processes. More complete quantum experiments also show that a complete retrieval of quantum states behind an interaction volume becomes impossible in principle.

  10. Quasar Astrophysics with the Space Interferometry Mission

    NASA Technical Reports Server (NTRS)

    Unwin, Stephen; Wehrle, Ann; Meier, David; Jones, Dayton; Piner, Glenn

    2007-01-01

    Optical astrometry of quasars and active galaxies can provide key information on the spatial distribution and variability of emission in compact nuclei. The Space Interferometry Mission (SIM PlanetQuest) will have the sensitivity to measure a significant number of quasar positions at the microarcsecond level. SIM will be very sensitive to astrometric shifts for objects as faint as V = 19. A variety of AGN phenomena are expected to be visible to SIM on these scales, including time and spectral dependence in position offsets between accretion disk and jet emission. These represent unique data on the spatial distribution and time dependence of quasar emission. It will also probe the use of quasar nuclei as fundamental astrometric references. Comparisons between the time-dependent optical photocenter position and VLBI radio images will provide further insight into the jet emission mechanism. Observations will be tailored to each specific target and science question. SIM will be able to distinguish spatially between jet and accretion disk emission; and it can observe the cores of galaxies potentially harboring binary supermassive black holes resulting from mergers.

  11. Clutter suppression interferometry system design and processing

    NASA Astrophysics Data System (ADS)

    Knight, Chad; Deming, Ross; Gunther, Jake

    2015-05-01

    Clutter suppression interferometry (CSI) has received extensive attention due to its multi-modal capability to detect slow-moving targets, and concurrently form high-resolution synthetic aperture radar (SAR) images from the same data. The ability to continuously augment SAR images with geo-located ground moving target indicators (GMTI) provides valuable real-time situational awareness that is important for many applications. CSI can be accomplished with minimal hardware and processing resources. This makes CSI a natural candidate for applications where size, weight and power (SWaP) are constrained, such as unmanned aerial vehicles (UAVs) and small satellites. This paper will discuss the theory for optimal CSI system configuration focusing on sparse time-varying transmit and receive array manifold due to SWaP considerations. The underlying signal model will be presented and discussed as well as the potential benefits that a sparse time-varying transmit receive manifold provides. The high-level processing objectives will be detailed and examined on simulated data. Then actual SAR data collected with the Space Dynamic Laboratory (SDL) FlexSAR radar system will be analyzed. The simulated data contrasted with actual SAR data helps illustrate the challenges and limitations found in practice vs. theory. A new novel approach incorporating sparse signal processing is discussed that has the potential to reduce false- alarm rates and improve detections.

  12. Optical vernier interferometry for aspheric metrology

    NASA Astrophysics Data System (ADS)

    Murphy, Paul E.; Brown, Thomas G.; Moore, Duncan T.

    1999-06-01

    The ease of manufacture and testing spherical optical surfaces has made them the default choice for optical systems. Optical designs could greatly benefit form aspheric surfaces; the use of aspherics for projection photolithography in particular puts increasingly greater demands on optical manufacturing. Extreme UV (EUV) lithography requires all reflective elements, some of which will likely be strong aspheres. Modeling software and manufacturing have outpaced aspheric metrology, and we must be able to measure an optical component to have any hope of fabricating it. We seek to extend the dynamic range of optical interferometry to include aspheric surface metrology. We employ two wavelengths to create a vernier effect, allowing the measurement of larger departures without fundamentally sacrificing measurement accuracy. Such large departures impose more rigorous specifications on the interferometer. We explain the new challenges in the acquisition and interpretation of aspheric surface data, and compare to conventional spherical testing. The interferometer optical components are modeled using OSLO SIX design tools. Preliminary experimental results confirm the theory of operation. Some obstacles to practical implementation were also observed, and will be addressed.

  13. Geodetic long baseline interferometry research in Canada

    NASA Technical Reports Server (NTRS)

    Langley, R. B.; Petrachenko, W. T.; Canon, W. H.

    1980-01-01

    The objectives and results of several studies using the Canadian long baseline interferometry system (LBI) are presented. The precision of measurements from radio telescopes at the Algonquin Radio Observatory (ARO), Lake Traverse, Ontario; the Owens Valley Radio Observatory (OVRO), Big Pine, California; and the Chilbolton Observatory (CHIL), Chilbolton, England, is discussed. Also, since LBI is insensitive to the uncertainty in the geocentric gravitational constant, it is a very useful technique for determining the scales of the coordinate systems used by other precise techniques. Beginning in May 1977, a number of LBI observing sessions were accompanied by simultaneous satellite Doppler observations. The baseline components obtained from the satellite Doppler observations were compared to the LBI values. The weighted mean scale bias of the NSWC 9Z-2 satellite Doppler coordinate system relative to the LBI system was found to be 0.42 + or - 0.05 PPM. The weighted mean difference in the origin of longitude was found to be 0.87 sec + or - 0.01 while the difference in declination origin was found to be 0.06 sec + or - 0.01.

  14. General Relativistic Effects in Atom Interferometry

    SciTech Connect

    Dimopoulos, Savas; Graham, Peter W.; Hogan, Jason M.; Kasevich, Mark A.; /Stanford U., Phys. Dept.

    2008-03-17

    Atom interferometry is now reaching sufficient precision to motivate laboratory tests of general relativity. We begin by explaining the non-relativistic calculation of the phase shift in an atom interferometer and deriving its range of validity. From this we develop a method for calculating the phase shift in general relativity. This formalism is then used to find the relativistic effects in an atom interferometer in a weak gravitational field for application to laboratory tests of general relativity. The potentially testable relativistic effects include the non-linear three-graviton coupling, the gravity of kinetic energy, and the falling of light. We propose experiments, one currently under construction, that could provide a test of the principle of equivalence to 1 part in 10{sup 15} (300 times better than the present limit), and general relativity at the 10% level, with many potential future improvements. We also consider applications to other metrics including the Lense-Thirring effect, the expansion of the universe, and preferred frame and location effects.

  15. Synchrotron Light Interferometry at Jefferson Lab

    SciTech Connect

    Arne Freyberger; Pavel Chevtsov; Anthony Day; William Hicks

    2004-07-01

    The hyper-nuclear physics program at JLAB requires an upper limit on the RMS momentum spread of {delta}p/p < 3 x 10{sup -5}. The momentum spread is determined by measuring the beam width at a dispersive location (D {approx} 4m) in the transport line to the experimental halls. Ignoring the epsilon-beta contribution to the intrinsic beam size, this momentum spread corresponds to an upper bound on the beam width of {sigma}{sub beam} < 120 {micro}m. Typical techniques to measure and monitor the beam size are either invasive or do not have the resolution to measure such small beam sizes. Using interferometry of the synchrotron light produced in the dispersive bend, the resolution of the optical system can be made very small. The non-invasive nature of this measurement allows continuous monitoring of the momentum spread. Two synchrotron light interferometers have been built and installed at JLAB, one each in the Hall-A and Hall-C transport lines. The devices operate over a beam current range from 20 {micro}A to 120 {micro}A and have a spatial resolution of 10um. The structure of the interferometers, the experience gained during its installation, beam measurements and momentum spread stability are presented. The dependence of the measured momentum spread on beam current will be presented.

  16. Bounding the Higgs boson width through interferometry.

    PubMed

    Dixon, Lance J; Li, Ye

    2013-09-13

    We study the change in the diphoton-invariant-mass distribution for Higgs boson decays to two photons, due to interference between the Higgs resonance in gluon fusion and the continuum background amplitude for gg→γγ. Previously, the apparent Higgs mass was found to shift by around 100 MeV in the standard model in the leading-order approximation, which may potentially be experimentally observable. We compute the next-to-leading-order QCD corrections to the apparent mass shift, which reduce it by about 40%. The apparent mass shift may provide a way to measure, or at least bound, the Higgs boson width at the Large Hadron Collider through "interferometry." We investigate how the shift depends on the Higgs width, in a model that maintains constant Higgs boson signal yields. At Higgs widths above 30 MeV, the mass shift is over 200 MeV and increases with the square root of the width. The apparent mass shift could be measured by comparing with the ZZ* channel, where the shift is much smaller. It might be possible to measure the shift more accurately by exploiting its strong dependence on the Higgs transverse momentum. PMID:24074073

  17. Radar Interferometry with Public Domain Tools

    NASA Astrophysics Data System (ADS)

    Kampes, B. M.; Hanssen, R. F.; Perski, Z.

    2004-06-01

    The development of public-domain software in the scientific community has stimulated a fast and free dissemination of ideas. Here we present latest contributions to public-domain radar interferometry software to create interferometric products and to analyze and visualize these products. We present the feasibility of the Doris radar interferometric software of Delft University of Technology to create ENVISAT interferometric products such as DEMs and deformation maps. A stepwise description of the creation of an ENVISAT DEM of the Las Vegas area is presented, using besides Doris the ESA BEAM toolbox, the statistical cost phase unwrapper SNAPHU (Stanford University), the Generic Mapping Tools (University of Hawaii), and the PROJ.4 package (USGS). Finally, the GRASS GIS software is used to drape a LandSAT image on top of the computed DEM in order to show the analysis and visualization capabilities of this free GIS package. These packages are also described briefly in this paper. Both advantages as well as drawbacks of these tools are discussed. It is the intention of this paper to demonstrate how a larger scientific community can benefit from freely available tools, and which contributions need to be solicited for.

  18. Thermal expansion of composites using Moire interferometry

    NASA Technical Reports Server (NTRS)

    Bowles, D. E.; Post, D.; Herakovich, C. T.; Tenny, D. R.

    1980-01-01

    An experimental technique for precise measurement of the thermal response of fiber-reinforced composite materials uses moire interferometry with fringe multiplication which yield a sensitivity of 833 nm (32.8 mu in.) per fringe. Results from the technique are compared with those obtained from electrical resistance strain gages, and also those predicted from classical lamination theory. Temperature dependent coefficients of thermal expansion for composite materials subjected to thermal cycling in the temperature range of 297 K (75 F) to 422 K (300 F) were determined for four laminate configurations (0, 90, 0/ + or - 45/90 sub s and 0/90/ + or - 45 sub s) of T300/5208 graphite epoxy, and ranged from -0.107 mu epsilon K/1 (-0.059 mu epsilon deg F/-) for the 0 laminate to 32.18 mu epsilon K/1 (17.88 mu epsilon F/1) for the 90 laminate. Moisture was found to greatly influence the thermal response of a quasi-isotropic laminate, resulting in hysteresis and residual compressive strain as the moisture content was reduced. Comparisons between moire and strain gage measurements were inconclusive with both techniques giving consistent but systematically different results. Differences of as much as 29% were observed.

  19. Multifrequency perturbations in matter-wave interferometry

    NASA Astrophysics Data System (ADS)

    Günther, A.; Rembold, A.; Schütz, G.; Stibor, A.

    2015-11-01

    High-contrast matter-wave interferometry is essential in various fundamental quantum mechanical experiments as well as for technical applications. Thereby, contrast and sensitivity are typically reduced by decoherence and dephasing effects. While decoherence accounts for a general loss of quantum information in a system due to entanglement with the environment, dephasing is due to collective time-dependent external phase shifts, which can be related to temperature drifts, mechanical vibrations, and electromagnetic oscillations. In contrast to decoherence, dephasing can, in principle, be reversed. Here, we demonstrate in experiment and theory a method for the analysis and reduction of the influence of dephasing noise and perturbations consisting of several external frequencies in an electron interferometer. This technique uses the high spatial and temporal resolution of a delay-line detector to reveal and remove dephasing perturbations by second-order correlation analysis. It allows matter-wave experiments under perturbing laboratory conditions and can be applied, in principle, to electron, atom, ion, neutron, and molecule interferometers.

  20. Detection of breast lesions by holographic interferometry

    NASA Astrophysics Data System (ADS)

    Hong, HyunDae; Sheffer, Daniel B.; Loughry, C. William

    1999-07-01

    The holographic interferometry (HI) technique commonly used for nondestructive testing of laminate materials was applied to create fringe contour distortion near the site of indwelling breast lesions. For this medical imaging application, the HI technique was successful in demonstrating abnormal mechanical properties of living tissue. Adequate density and contrast of fringes, crucial factors necessary for analysis of surface deformation of an object, can be made only with an appropriate stressing method. We have applied vibration and mild pressure to the surface of female breasts for the purpose of detecting localized densities and mass alterations of the tissue, which may be indicative of an abnormality of that tissue. Even though each stressing method had both positive and negative aspects, pneumatic pressure was adopted for the present study because it was more suitable for a noninvasive and noncontact breast examination. We also developed a computer based holographic imaging system to precisely control the stressing phase for the pressure and laser triggering so the resultant holograms had manageable fringe density and repeatability.

  1. Two-dimensional laser interferometry analysis

    NASA Astrophysics Data System (ADS)

    Mehr, Leo; Concepcion, Ricky; Duggan, Robert; Moore, Hannah; Novick, Asher; Ransohoff, Lauren; Gourdain, Pierre-Alexandre; Hammer, David; Kusse, Bruce

    2013-10-01

    The objective of our research was to create a two-dimensional interferometer which we will use to measure plasma densities at the Cornell Research Beam Accelerator (COBRA). We built two shearing interferometers and mounted them on an optics table. They intercept the probe laser beam which travels directly through the plasma and is captured by a 16-bit CCD camera. In comparing the interferometer images before the shot and during the plasma shot, we observed both lateral and vertical shifts in the interference pattern caused by the change of the refractive index due to the plasma electrons. We developed a computer program using Matlab to map a vector field depicting the shift between the two images. This shift is proportional to the line integral of electron density through the plasma chamber. We show this method provides a reliable way to determine the plasma electron density profile. Additionally, we hope this method can improve upon the diagnostic capabilities and efficiency of data collection used with standard one-dimensional interferometry. Undergraduate.

  2. Speckle reference beam holographic and speckle photographic interferometry in non-destructive test systems

    NASA Technical Reports Server (NTRS)

    Liu, H. K.

    1976-01-01

    The techniques of speckle beam holographic interferometry and speckle photographic interferometry are described. In particular, their practical limitations and their applications to the existing holographic nondestructive test system are discussed.

  3. Interferometry in the Era of Very Large Telescopes

    NASA Technical Reports Server (NTRS)

    Barry, Richard K.

    2010-01-01

    Research in modern stellar interferometry has focused primarily on ground-based observatories, with very long baselines or large apertures, that have benefited from recent advances in fringe tracking, phase reconstruction, adaptive optics, guided optics, and modern detectors. As one example, a great deal of effort has been put into development of ground-based nulling interferometers. The nulling technique is the sparse aperture equivalent of conventional coronography used in filled aperture telescopes. In this mode the stellar light itself is suppressed by a destructive fringe, effectively enhancing the contrast of the circumstellar material located near the star. Nulling interferometry has helped to advance our understanding of the astrophysics of many distant objects by providing the spatial resolution necessary to localize the various faint emission sources near bright objects. We illustrate the current capabilities of this technique by describing the first scientific results from the Keck Interferometer Nuller that combines the light from the two largest optical telescopes in the world including new, unpublished measurements of exozodiacal dust disks. We discuss prospects in the near future for interferometry in general, the capabilities of secondary masking interferometry on very large telescopes, and of nulling interferometry using outriggers on very large telescopes. We discuss future development of a simplified space-borne NIR nulling architecture, the Fourier-Kelvin Stellar Interferometer, capable of detecting and characterizing an Earth twin in the near future and how such a mission would benefit from the optical wavelength coverage offered by large, ground-based instruments.

  4. Elastic properties of transparent nano-polycrystalline diamond measured by GHz-ultrasonic interferometry and resonant sphere methods

    NASA Astrophysics Data System (ADS)

    Chang, Yun-Yuan; Jacobsen, Steven D.; Kimura, Masaki; Irifune, Tetsuo; Ohno, Ichiro

    2014-03-01

    The sound velocities and elastic moduli of transparent nano-polycrystalline diamond (NPD) have been determined by GHz-ultrasonic interferometry on three different bulk samples, and by resonant spectroscopy on a spherically fabricated NPD sample. We employ a newly-developed optical contact micrometer to measure the thickness of ultrasonic samples to ±0.05 μm with a spatial resolution of ∼50 μm in the same position of the GHz-ultrasonic measurements, resulting in acoustic-wave sound velocity measurements with uncertainties of 0.005-0.02%. The isotropic and adiabatic bulk and shear moduli of NPD measured by GHz-ultrasonic interferometry are KS0 = 442.5 (±0.5) GPa and G0 = 532.4 (±0.5) GPa. By rotating the shear-wave polarization direction, we observe no transverse anisotropy in this NPD. Using resonant sphere spectroscopy, we obtain KS0 = 440.3 (±0.5) GPa and G0 = 532.7 (±0.4) GPa. For comparison, we also measured by GHz-ultrasonic interferometry the elastic constants of a natural single-crystal type-IA diamond with about one-half the experimental uncertainty of previous measurements. The resulting Voigt-Reuss-Hill averaged bulk and shear moduli of natural diamond are KS0 = 441.8 (±0.8) GPa and G0 = 532.6 (±0.5) GPa, demonstrating that the bulk-elastic properties of transparent NPD are equivalent to natural single-crystal diamond as calculated from polycrystalline averaging of its elastic constants.

  5. Acoustic Neuroma Association

    MedlinePlus

    ... Platinum Sponsors More from this sponsor... Platinum Sponsor Gold Sponsor University of Colorado Acoustic Neuroma Program Rocky Mountain Gamma Knife Center Gold Sponsor NYU Langone Medical Center Departments of Neurosurgery ...

  6. Compact acoustic refrigerator

    DOEpatents

    Bennett, Gloria A.

    1992-01-01

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits (22), in a borehole environment. An acoustic engine (12, 14) includes first thermodynamic elements (12) for generating a standing acoustic wave in a selected medium. An acoustic refrigerator (16, 26, 28) includes second thermodynamic elements (16) located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements (16) and a relatively hot temperature at a second end of the second thermodynamic elements (16). A resonator volume (18) cooperates with the first and second thermodynamic elements (12, 16) to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements (12, 16), first heat pipes (24, 26) transfer heat from the heat load (22) to the second thermodynamic elements (16) and second heat pipes (28, 32) transfer heat from first and second thermodynamic elements (12, 16) to the borehole environment.

  7. Acoustic imaging system

    DOEpatents

    Smith, Richard W.

    1979-01-01

    An acoustic imaging system for displaying an object viewed by a moving array of transducers as the array is pivoted about a fixed point within a given plane. A plurality of transducers are fixedly positioned and equally spaced within a laterally extending array and operatively directed to transmit and receive acoustic signals along substantially parallel transmission paths. The transducers are sequentially activated along the array to transmit and receive acoustic signals according to a preestablished sequence. Means are provided for generating output voltages for each reception of an acoustic signal, corresponding to the coordinate position of the object viewed as the array is pivoted. Receptions from each of the transducers are presented on the same display at coordinates corresponding to the actual position of the object viewed to form a plane view of the object scanned.

  8. Acoustics lecturing in Mexico

    NASA Astrophysics Data System (ADS)

    Beristain, Sergio

    2002-11-01

    Some thirty years ago acoustics lecturing started in Mexico at the National Polytechnic Institute in Mexico City, as part of the Bachelor of Science degree in Communications and Electronics Engineering curricula, including the widest program on this field in the whole country. This program has been producing acoustics specialists ever since. Nowadays many universities and superior education institutions around the country are teaching students at the B.Sc. level and postgraduate level many topics related to acoustics, such as Architectural Acoustics, Seismology, Mechanical Vibrations, Noise Control, Audio, Audiology, Music, etc. Also many institutions have started research programs in related fields, with participation of medical doctors, psychologists, musicians, engineers, etc. Details will be given on particular topics and development.

  9. Compact acoustic refrigerator

    SciTech Connect

    Bennett, G.A.

    1991-12-31

    This invention is comprised of a compact acoustic refrigeration system that actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment.

  10. Compact acoustic refrigerator

    DOEpatents

    Bennett, G.A.

    1992-11-24

    A compact acoustic refrigeration system actively cools components, e.g., electrical circuits, in a borehole environment. An acoustic engine includes first thermodynamic elements for generating a standing acoustic wave in a selected medium. An acoustic refrigerator includes second thermodynamic elements located in the standing wave for generating a relatively cold temperature at a first end of the second thermodynamic elements and a relatively hot temperature at a second end of the second thermodynamic elements. A resonator volume cooperates with the first and second thermodynamic elements to support the standing wave. To accommodate the high heat fluxes required for heat transfer to/from the first and second thermodynamic elements, first heat pipes transfer heat from the heat load to the second thermodynamic elements and second heat pipes transfer heat from first and second thermodynamic elements to the borehole environment. 18 figs.

  11. Numerical Techniques in Acoustics

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J. (Compiler)

    1985-01-01

    This is the compilation of abstracts of the Numerical Techniques in Acoustics Forum held at the ASME's Winter Annual Meeting. This forum was for informal presentation and information exchange of ongoing acoustic work in finite elements, finite difference, boundary elements and other numerical approaches. As part of this forum, it was intended to allow the participants time to raise questions on unresolved problems and to generate discussions on possible approaches and methods of solution.

  12. Assessment of a direct acoustic cochlear stimulator.

    PubMed

    Chatzimichalis, Michail; Sim, Jae Hoon; Huber, Alexander M

    2012-01-01

    This study aimed to assess the functional results of a new, active, acoustic-mechanical hearing implant, the Direct Acoustic Cochlear Stimulation Partial Implant (DACS PI), in a preclinical study. The DACS PI is an electromagnetic device fixed to the mastoid by screws and coupled to a standard stapes prosthesis by an artificial incus (AI). The function of the DACS PI-aided reconstruction was assessed by determining: (1) the maximum equivalent sound pressure level (SPL) of the implant, which was obtained from measurements of the volume displacement at the round window in normal and implanted ears, and (2) the quality at the coupling interface between the AI of the DACS and the stapes prosthesis, which was quantified from measurements of relative motions between the AI and the prosthesis. Both measurements were performed with fresh temporal bones using a scanning laser Doppler interferometry system. The expected maximum equivalent SPL with a typical driving voltage of 0.3 V was about 115-125 dB SPL up to 1.5 kHz in reconstruction with the DACS PI, and decreased with a roll-off slope of about 65 dB/decade, reaching 90 dB SPL at 8 kHz. The large roll-off relative to a normal ear was presumed to be a relatively high inductive impedance of the coil of the DACS PI actuator at higher frequencies. Good coupling quality between the AI and the prosthesis was achieved below the resonance (∼1.5 kHz) of the DACS PI for all tested stapes prostheses. Above the resonance, the SMart Piston, which is composed of a shape-memory alloy, had the best coupling quality. PMID:22739432

  13. Wavefront modulation and subwavelength diffractive acoustics with an acoustic metasurface.

    PubMed

    Xie, Yangbo; Wang, Wenqi; Chen, Huanyang; Konneker, Adam; Popa, Bogdan-Ioan; Cummer, Steven A

    2014-01-01

    Metasurfaces are a family of novel wavefront-shaping devices with planar profile and subwavelength thickness. Acoustic metasurfaces with ultralow profile yet extraordinary wave manipulating properties would be highly desirable for improving the performance of many acoustic wave-based applications. However, designing acoustic metasurfaces with similar functionality to their electromagnetic counterparts remains challenging with traditional metamaterial design approaches. Here we present a design and realization of an acoustic metasurface based on tapered labyrinthine metamaterials. The demonstrated metasurface can not only steer an acoustic beam as expected from the generalized Snell's law, but also exhibits various unique properties such as conversion from propagating wave to surface mode, extraordinary beam-steering and apparent negative refraction through higher-order diffraction. Such designer acoustic metasurfaces provide a new design methodology for acoustic signal modulation devices and may be useful for applications such as acoustic imaging, beam steering, ultrasound lens design and acoustic surface wave-based applications. PMID:25418084

  14. Acoustic communication by ants

    NASA Astrophysics Data System (ADS)

    Hickling, Robert

    2002-05-01

    Many ant species communicate acoustically by stridulating, i.e., running a scraper over a washboard-like set of ridges. Ants appear to be insensitive to airborne sound. Consequently, myrmecologists have concluded that the stridulatory signals are transmitted through the substrate. This has tended to diminish the importance of acoustic communication, and it is currently believed that ant communication is based almost exclusively on pheromones, with acoustic communication assigned an almost nonexistent role. However, it can be shown that acoustic communication between ants is effective only if the medium is air and not the substrate. How, then, is it possible for ants to appear deaf to airborne sound and yet communicate through the air? An explanation is provided in a paper [R. Hickling and R. L. Brown, ``Analysis of acoustic communication by ants,'' J. Acoust. Soc. Am. 108, 1920-1929 (2000)]. Ants are small relative to the wavelengths they generate. Hence, they create a near field, which is characterized by a major increase in sound velocity (particle velocity of sound) in the vicinity of the source. Hair sensilla on the ants' antennae respond to sound velocity. Thus, ants are able to detect near-field sound from other ants and to exclude extraneous airborne sound.

  15. Acoustic detection of pneumothorax

    NASA Astrophysics Data System (ADS)

    Mansy, Hansen A.; Royston, Thomas J.; Balk, Robert A.; Sandler, Richard H.

    2003-04-01

    This study aims at investigating the feasibility of using low-frequency (<2000 Hz) acoustic methods for medical diagnosis. Several candidate methods of pneumothorax detection were tested in dogs. In the first approach, broadband acoustic signals were introduced into the trachea during end-expiration and transmitted waves were measured at the chest surface. Pneumothorax was found to consistently decrease pulmonary acoustic transmission in the 200-1200-Hz frequency band, while less change was observed at lower frequencies (p<0.0001). The ratio of acoustic energy between low (<220 Hz) and mid (550-770 Hz) frequency bands was significantly different in the control (healthy) and pneumothorax states (p<0.0001). The second approach measured breath sounds in the absence of an external acoustic input. Pneumothorax was found to be associated with a preferential reduction of sound amplitude in the 200- to 700-Hz range, and a decrease of sound amplitude variation (in the 300 to 600-Hz band) during the respiration cycle (p<0.01 for each). Finally, chest percussion was implemented. Pneumothorax changed the frequency and decay rate of percussive sounds. These results imply that certain medical conditions may be reliably detected using appropriate acoustic measurements and analysis. [Work supported by NIH/NHLBI #R44HL61108.

  16. Ocean acoustic reverberation tomography.

    PubMed

    Dunn, Robert A

    2015-12-01

    Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., <10 km), the acoustic wave field densely samples properties of the water column over the width of the receiver array. A method, referred to as ocean acoustic reverberation tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography. PMID:26723303

  17. Evaluation by holographic interferometry of impact damage in composite aeronautical structures

    NASA Astrophysics Data System (ADS)

    Ferraro, Pietro

    1992-01-01

    The results of an experimental study of holographic interferometry for impact damage detection and evaluation, in composite aeronautical sandwich structures is presented. The results show that holographic interferometry using thermal loading can accurately estimate delaminated areas on test samples in respect to ultrasonic inspection. The capability of holographic interferometry for detection of such damages in large composite components is shown also.

  18. Capabilities of Imaging Interferometry for Plasma Diagnostics in Open Systems

    SciTech Connect

    Vyacheslavov, L.N.; Sanin, A.L.; Tanaka, K.; Kawahata, K.

    2005-01-15

    Two modifications of imaging interferometry: heterodyne (HI) and phase contrast interferometers (PCI) are designed for observation of plasma density profiles and density fluctuations respectively. Besides, spatial distributions of plasma velocities, velocities fluctuations and related electrical fields can be obtained from the analysis of HI and PCI data. New sensitive phase counters, developed at Budker Institute of Nuclear Physics, enable HI to include some capabilities of the PCI. In addition to well recognized transversal spatial resolution of imaging technique, progress in deconvolution of line-of-sight-integrated data was recently made. Computer simulation, bench-test experiments and recent experimental results from the Large Helical Device illustrate the potentials of the imaging interferometry for investigation of plasma. Application of the imaging interferometry with spatial resolution along the viewing line to mirror machines is finally considered.

  19. Resolving microstructures in Z pinches with intensity interferometry

    SciTech Connect

    Apruzese, J. P.; Kroupp, E.; Maron, Y.; Giuliani, J. L.; Thornhill, J. W.

    2014-03-15

    Nearly 60 years ago, Hanbury Brown and Twiss [R. Hanbury Brown and R. Q. Twiss, Nature 178, 1046 (1956)] succeeded in measuring the 30 nrad angular diameter of Sirius using a new type of interferometry that exploited the interference of photons independently emitted from different regions of the stellar disk. Its basis was the measurement of intensity correlations as a function of detector spacing, with no beam splitting or preservation of phase information needed. Applied to Z pinches, X pinches, or laser-produced plasmas, this method could potentially provide spatial resolution under one micron. A quantitative analysis based on the work of Purcell [E. M. Purcell, Nature 178, 1449 (1956)] reveals that obtaining adequate statistics from x-ray interferometry of a Z-pinch microstructure would require using the highest-current generators available. However, using visible light interferometry would reduce the needed photon count and could enable its use on sub-MA machines.

  20. The application of interferometry to optical astronomical imaging.

    PubMed

    Baldwin, John E; Haniff, Christopher A

    2002-05-15

    In the first part of this review we survey the role optical/infrared interferometry now plays in ground-based astronomy. We discuss in turn the origins of astronomical interferometry, the motivation for its development, the techniques of its implementation, examples of its astronomical significance, and the limitations of the current generation of interferometric arrays. The second part focuses on the prospects for ground-based astronomical imaging interferometry over the near to mid-term (i.e. 10 years) at optical and near-infrared wavelengths. An assessment is made of the astronomical and technical factors which determine the optimal designs for imaging arrays. An analysis based on scientific capability, technical feasibility and cost argues for an array of large numbers of moderate-sized (2 m class) telescopes rather than one comprising a small number of much larger collectors. PMID:12804289

  1. Advances in Astrometry and Geophysics Made Possible by Radio Interferometry

    NASA Astrophysics Data System (ADS)

    Johnston, Kenneth J.

    1998-01-01

    Radio Interferometry has had a tremendous impact on the development of astrometry and geodesy. Barry Clark has played a leading role in developing the technology of radio interferometry through his work on connected-element interferometry, i.e., the Green Bank Interferometer and Very Large Array; and VLBI, i.e., the Mark I and II VLBI systems and the Very Long Baseline Array (VLBA). These efforts resulted in an increase in astrometric accuracy of four orders of magnitude. Stellar positions at radio wavelengths now can be measured with a precision of 0.1 milliarcseconds (mas). Earth orientation parameters such as UT1 and polar motion are now measured with precisions of 10 microarcseconds (micronas). The precession constants and models for nutation need revision to precisions at the microarcsecond level. Tectonic plate motion was directly measured in the 1980s. These were and are exciting times for research in these fields and Barry's scientific career parallels them especially in astrometry.

  2. A publication database for optical long baseline interferometry

    NASA Astrophysics Data System (ADS)

    Malbet, Fabien; Mella, Guillaume; Lawson, Peter; Taillifet, Esther; Lafrasse, Sylvain

    2010-07-01

    Optical long baseline interferometry is a technique that has generated almost 850 refereed papers to date. The targets span a large variety of objects from planetary systems to extragalactic studies and all branches of stellar physics. We have created a database hosted by the JMMC and connected to the Optical Long Baseline Interferometry Newsletter (OLBIN) web site using MySQL and a collection of XML or PHP scripts in order to store and classify these publications. Each entry is defined by its ADS bibcode, includes basic ADS informations and metadata. The metadata are specified by tags sorted in categories: interferometric facilities, instrumentation, wavelength of operation, spectral resolution, type of measurement, target type, and paper category, for example. The whole OLBIN publication list has been processed and we present how the database is organized and can be accessed. We use this tool to generate statistical plots of interest for the community in optical long baseline interferometry.

  3. The Beauty and Limitations of 10 Micron Heterodyne Interferometry (ISI)

    NASA Technical Reports Server (NTRS)

    Danchi, William C.

    2003-01-01

    Until recently, heterodyne interferometry at 10 microns has been the only successful technique for stellar interferometry in the very difficult atmospheric window from 9-12 microns. For most of its operational lifetime the U.C. Berkeley Infrared Spatial Interferometer was a single-baseline two telescope (1.65 m aperture) system using CO2 lasers as local oscillators. This instrument was designed and constructed from 1983-1988, and first fringes were obtained at Mt. Wilson in June 1988. During the past few years, a third telescope was constructed and just recently the first closure phases were obtained at 11.15 microns. We discuss the history, physics and technology of heterodyne interferometry in the mid-infrared, and some key astronomical results that have come from this unique instrument.

  4. Infrasonic interferometry of stratospherically refracted microbaroms--a numerical study.

    PubMed

    Fricke, Julius T; El Allouche, Nihed; Simons, Dick G; Ruigrok, Elmer N; Wapenaar, Kees; Evers, Läslo G

    2013-10-01

    The atmospheric wind and temperature can be estimated through the traveltimes of infrasound between pairs of receivers. The traveltimes can be obtained by infrasonic interferometry. In this study, the theory of infrasonic interferometry is verified and applied to modeled stratospherically refracted waves. Synthetic barograms are generated using a raytracing model and taking into account atmospheric attenuation, geometrical spreading, and phase shifts due to caustics. Two types of source wavelets are implemented for the experiments: blast waves and microbaroms. In both numerical experiments, the traveltimes between the receivers are accurately retrieved by applying interferometry to the synthetic barograms. It is shown that microbaroms can be used in practice to obtain the traveltimes of infrasound through the stratosphere, which forms the basis for retrieving the wind and temperature profiles. PMID:24116404

  5. Progress in electron- and ion-interferometry

    NASA Astrophysics Data System (ADS)

    Hasselbach, Franz

    2010-01-01

    In the 1970s the prominent goal was to overcome the limitations of electron microscopy caused by aberrations of electron lenses by the development of electron holography. In the meantime this problem has been solved, not only in the roundabout way of holography, but directly by correcting the aberrations of the lenses. Nevertheless, many quantitative electron microscopical measurement methods—e.g. mapping and visualization of electric and magnetic fields—were developed within the context of holography and have become fields of their own. In this review we focus on less popular electron interferometric experiments which complement the field of electron holography. The paper is organized as follows. After a short sketch of the development of electron biprism interferometry after its invention in 1954, recent advances in technology are discussed that made electron biprism interferometry an indispensable tool for solving fundamental and applied questions in physics: the development and preparation of conventional and single-atom field electron and field ion sources with their extraordinary properties. Single- and few-atom sources exhibit spectacular features: their brightness at 100 keV exceeds that of conventional field emitters by two orders in magnitude. Due to the extremely small aberrations of diode field emitter extraction optics, the virtual source size of single-atom tips is on the order of 0.2 nm. As a consequence it illuminates an area 7 cm in diameter on a screen at a distance of 15 cm coherently. Projection electron micrographs taken with these sources reach spatial resolutions of atomic dimensions and in-line holograms are—due to the absence of lenses with their aberrations—not blurred. Their reconstruction is straightforward. By addition of a carbon nanotube biprism into the beam path of a projection microscope a lensless electron interferometer has been realized. In extremely ultrahigh vacuum systems flicker noise is practically absent in the new

  6. Acoustic calibration apparatus for calibrating plethysmographic acoustic pressure sensors

    NASA Technical Reports Server (NTRS)

    Zuckerwar, Allan J. (Inventor); Davis, David C. (Inventor)

    1995-01-01

    An apparatus for calibrating an acoustic sensor is described. The apparatus includes a transmission material having an acoustic impedance approximately matching the acoustic impedance of the actual acoustic medium existing when the acoustic sensor is applied in actual in-service conditions. An elastic container holds the transmission material. A first sensor is coupled to the container at a first location on the container and a second sensor coupled to the container at a second location on the container, the second location being different from the first location. A sound producing device is coupled to the container and transmits acoustic signals inside the container.

  7. Bayesian Methodology for the Space Interferometry Mission

    NASA Astrophysics Data System (ADS)

    Loredo, T. J.; Chernoff, D. F.

    2000-05-01

    We will describe work in progress on the development of Bayesian methodology for the analysis of data from the Space Interferometry Mission (SIM). There are two main thrusts to this work: development of new methods for the detection and analysis of Keplerian reflex motion in astrometric data; and adaptive experimental design for on-the-fly refinement of the SIM grid. For detection and measurement of reflex motions (e.g., from planetary companions), we use the algorithm developed by Bretthorst for the Bayesian analysis of superposed nonlinear models to develop an alternative to the commonly used Lomb-Scargle (LS) periodogram that we call the Kepler periodogram. The LS periodogram emerges as a special case of the Kepler periodogram when the data are 1-dimensional (e.g., radial velocity (RV) measurements) and the bodies in question are in a circular orbit. But the Kepler periodogram generalizes the LS periodogram to account for orbital eccentricity, higher dimensional data (e.g., astrometric data, or a combination of astrometric and RV data), and sources of systematic error such as uncertainty in inertial motion. We use the Bayesian theory of experimental design to develop adaptive strategies for SIM observing. This includes identifying the best sampling scheme for detecting and monitoring Keplerian reflex motions in science targets, and (perhaps more crucially) the adaptive refinement of the SIM astrometric grid from observations of candidate grid stars throughout the SIM mission. Included in this latter task are classification of candidate grid objects as inertial or noninertial and scheduling of observations to best update our knowledge of grid star motions.

  8. Integrated Optics Achromatic Nuller for Stellar Interferometry

    NASA Technical Reports Server (NTRS)

    Ksendzov, Alexander

    2012-01-01

    This innovation will replace a beam combiner, a phase shifter, and a mode conditioner, thus simplifying the system design and alignment, and saving weight and space in future missions. This nuller is a dielectric-waveguide-based, four-port asymmetric coupler. Its nulling performance is based on the mode-sorting property of adiabatic asymmetric couplers that are intrinsically achromatic. This nuller has been designed, and its performance modeled, in the 6.5-micrometer to 9.25-micrometer spectral interval (36% bandwidth). The calculated suppression of starlight for this 15-cm-long device is 10(exp -5) or better through the whole bandwidth. This is enough to satisfy requirements of a flagship exoplanet-characterization mission. Nulling interferometry is an approach to starlight suppression that will allow the detection and spectral characterization of Earth-like exoplanets. Nulling interferometers separate the light originating from a dim planet from the bright starlight by placing the star at the bottom of a deep, destructive interference fringe, where the starlight is effectively cancelled, or nulled, thus allowing the faint off-axis light to be much more easily seen. This process is referred to as nulling of the starlight. Achromatic nulling technology is a critical component that provides the starlight suppression in interferometer-based observatories. Previously considered space-based interferometers are aimed at approximately 6-to-20-micrometer spectral range. While containing the spectral features of many gases that are considered to be signatures of life, it also offers better planet-to-star brightness ratio than shorter wavelengths. In the Integrated Optics Achromatic Nuller (IOAN) device, the two beams from the interferometer's collecting telescopes pass through the same focusing optic and are incident on the input of the nuller.

  9. Detection of deoxynivalenol using biolayer interferometry.

    PubMed

    Maragos, Chris M

    2011-08-01

    Biolayer interferometry allows for the real time monitoring of the interactions between molecules without the need for reagents with enzymatic, fluorescent, or radioactive labels. The technology is based upon the changes in interference pattern of light reflected from the surface of an optical fiber when materials bind to the tip of the fiber. The technique represents an alternative to technologies such as surface plasmon resonance, with an advantage in that the flow of extracts through small capillaries is not required. In this report, a deoxynivalenol-bovine serum albumin (DON-BSA) conjugate was non-covalently immobilized to the surface of aminopropylsilane sensors and the change in interference pattern resulting from the binding of DON-specific antibodies was measured. The basis for the assay was the competition between DON and the immobilized DON-BSA for binding to limited amounts of antibody. The technique was used to measure DON in extracts of spiked whole wheat flour, with a limit of detection of 0.10 mg DON/kg. Matrix interferences were an issue, and adequate quantification required using matrix-matched standards. When samples were tested with sensors that had not been conditioned to remove loosely attached DON-BSA, the recoveries at five spiking levels over the range from 0.2 to 5 mg/kg averaged 108.8% [relative standard deviation (RSD) 16.0%]. Using sensors that had been conditioned lowered the average recovery (101.4%) and improved the RSD (13.2%). This suggests that conditioning the sensors helped reduce a bias in the assay towards overestimation. These results, and the ease with which assays can be conducted, suggest further exploration of this technology for detection of mycotoxins is warranted. PMID:23605795

  10. Single-mode fiber, velocity interferometry

    SciTech Connect

    Krauter, K. G.; Jacobson, G. F.; Patterson, J. R.; Nguyen, J. H.; Ambrose, W. P.

    2011-04-15

    In this paper, we describe a velocity interferometer system based entirely on single-mode fiber optics. This paper includes a description of principles used in developing the single-mode velocity interferometry system (SMV). The SMV design is based on polarization-insensitive components. Polarization adjusters are included to eliminate the effects of residual birefringence and polarization dependent losses in the interferometers. Characterization measurements and calibration methods needed for data analysis and a method of data analysis are described. Calibration is performed directly using tunable lasers. During development, we demonstrated its operation using exploding-foil bridge-wire fliers up to 200 m/s. In a final test, we demonstrated the SMV in a gas gun experiment up to 1.2 km/sec. As a basis for comparison in the gas gun experiment, we used another velocimetry technique that is also based on single-mode fiber optics: photonic Doppler velocimetry (PDV). For the gas gun experiment, we split the light returned from a single target spot and performed a direct comparison of the homodyne (SMV) and heterodyne (PDV) techniques concurrently. The two techniques had a negligible mean difference and a 1.5% standard deviation in the one-dimensional shock zone. Within one interferometer delay time after a sudden Doppler shift, a SMV unencumbered by multimode-fiber dispersion exhibits two color beats. These beats have the same period as PDV beats--this interference occurs between the ''recently'' shifted and ''formerly unshifted'' paths within the interferometer. We believe that recognizing this identity between homodyne and heterodyne beats is novel in the shock-physics field. SMV includes the conveniences of optical fiber, while removing the time resolution limitations associated with the multimode delivery fiber.

  11. Single-mode fiber, velocity interferometry.

    PubMed

    Krauter, K G; Jacobson, G F; Patterson, J R; Nguyen, J H; Ambrose, W P

    2011-04-01

    In this paper, we describe a velocity interferometer system based entirely on single-mode fiber optics. This paper includes a description of principles used in developing the single-mode velocity interferometry system (SMV). The SMV design is based on polarization-insensitive components. Polarization adjusters are included to eliminate the effects of residual birefringence and polarization dependent losses in the interferometers. Characterization measurements and calibration methods needed for data analysis and a method of data analysis are described. Calibration is performed directly using tunable lasers. During development, we demonstrated its operation using exploding-foil bridge-wire fliers up to 200 m/s. In a final test, we demonstrated the SMV in a gas gun experiment up to 1.2 km/sec. As a basis for comparison in the gas gun experiment, we used another velocimetry technique that is also based on single-mode fiber optics: photonic Doppler velocimetry (PDV). For the gas gun experiment, we split the light returned from a single target spot and performed a direct comparison of the homodyne (SMV) and heterodyne (PDV) techniques concurrently. The two techniques had a negligible mean difference and a 1.5% standard deviation in the one-dimensional shock zone. Within one interferometer delay time after a sudden Doppler shift, a SMV unencumbered by multimode-fiber dispersion exhibits two color beats. These beats have the same period as PDV beats-this interference occurs between the "recently" shifted and "formerly unshifted" paths within the interferometer. We believe that recognizing this identity between homodyne and heterodyne beats is novel in the shock-physics field. SMV includes the conveniences of optical fiber, while removing the time resolution limitations associated with the multimode delivery fiber. PMID:21529042

  12. Seismic interferometry by multidimensional deconvolution without wavefield separation

    NASA Astrophysics Data System (ADS)

    Ravasi, Matteo; Meles, Giovanni; Curtis, Andrew; Rawlinson, Zara; Yikuo, Liu

    2015-07-01

    Seismic interferometry comprises a suite of methods to redatum recorded wavefields to those that would have been recorded if different sources (so-called virtual sources) had been activated. Seismic interferometry by cross-correlation has been formulated using either two-way (for full wavefields) or one-way (for directionally decomposed wavefields) representation theorems. To obtain improved Green's function estimates, the cross-correlation result can be deconvolved by a quantity that identifies the smearing of the virtual source in space and time, the so-called point-spread function. This type of interferometry, known as interferometry by multidimensional deconvolution (MDD), has so far been applied only to one-way directionally decomposed fields, requiring accurate wavefield decomposition from dual (e.g. pressure and velocity) recordings. Here we propose a form of interferometry by multidimensional deconvolution that uses full wavefields with two-way representations, and simultaneously invert for pressure and (normal) velocity Green's functions, rather than only velocity responses as for its one-way counterpart. Tests on synthetic data show that two-way MDD improves on results of interferometry by cross-correlation, and generally produces estimates of similar quality to those obtained by one-way MDD, suggesting that the preliminary decomposition into up- and downgoing components of the pressure field is not required if pressure and velocity data are jointly used in the deconvolution. We also show that constraints on the directionality of the Green's functions sought can be added directly into the MDD inversion process to further improve two-way multidimensional deconvolution. Finally, as a by-product of having pressure and particle velocity measurements, we adapt one- and two-way representation theorems to convert any particle velocity receiver into its corresponding virtual dipole/gradient source by means of MDD. Thus data recorded from standard monopolar (e

  13. Coda Wave Interferometry Method Applied in Structural Monitoring to Assess Damage Evolution in Masonry and Concrete Structures

    NASA Astrophysics Data System (ADS)

    Masera, D.; Bocca, P.; Grazzini, A.

    2011-07-01

    In this experimental program the main goal is to monitor the damage evolution in masonry and concrete structures by Acoustic Emission (AE) signal analysis applying a well-know seismic method. For this reason the concept of the coda wave interferometry is applied to AE signal recorded during the tests. Acoustic Emission (AE) are very effective non-destructive techniques applied to identify micro and macro-defects and their temporal evolution in several materials. This technique permits to estimate the velocity of ultrasound waves propagation and the amount of energy released during fracture propagation to obtain information on the criticality of the ongoing process. By means of AE monitoring, an experimental analysis on a set of reinforced masonry walls under variable amplitude loading and strengthening reinforced concrete (RC) beams under monotonic static load has been carried out. In the reinforced masonry wall, cyclic fatigue stress has been applied to accelerate the static creep and to forecast the corresponding creep behaviour of masonry under static long-time loading. During the tests, the evaluation of fracture growth is monitored by coda wave interferometry which represents a novel approach in structural monitoring based on AE relative change velocity of coda signal. In general, the sensitivity of coda waves has been used to estimate velocity changes in fault zones, in volcanoes, in a mining environment, and in ultrasound experiments. This method uses multiple scattered waves, which travelled through the material along numerous paths, to infer tiny temporal changes in the wave velocity. The applied method has the potential to be used as a "damage-gauge" for monitoring velocity changes as a sign of damage evolution into masonry and concrete structures.

  14. Information-recycling beam splitters for quantum enhanced atom interferometry.

    PubMed

    Haine, S A

    2013-02-01

    We propose a scheme to significantly enhance the sensitivity of atom interferometry performed with Bose-Einstein condensates. When an optical two-photon Raman transition is used to split the condensate into two modes, some information about the number of atoms in one of the modes is contained in one of the optical modes. We introduce a simple model to describe this process, and find that by processing this information in an appropriate way, the phase sensitivity of atom interferometry can be enhanced by more than a factor of 10 for realistic parameters. PMID:23414016

  15. Modulated Source Interferometry with Combined Amplitude and Frequency Modulation

    NASA Technical Reports Server (NTRS)

    Gutierrez, Roman C. (Inventor)

    1998-01-01

    An improved interferometer is produced by modifying a conventional interferometer to include amplitude and/or frequency modulation of a coherent light source at radio or higher frequencies. The phase of the modulation signal can be detected in an interfering beam from an interferometer and can be used to determine the actual optical phase of the beam. As such, this improvement can be adapted to virtually any two-beam interferometer, including: Michelson, Mach-Zehnder, and Sagnac interferometers. The use of an amplitude modulated coherent tight source results in an interferometer that combines the wide range advantages of coherent interferometry with the precise distance measurement advantages of white light interferometry.

  16. Random phase-shifting interferometry based on independent component analysis

    NASA Astrophysics Data System (ADS)

    Xu, Xiaofei; Lu, Xiaoxu; Tian, Jindong; Shou, Junwei; Zheng, Dejin; Zhong, Liyun

    2016-07-01

    In random phase-shifting interferometry, a novel phase retrieval algorithm is proposed based on the independent component analysis (ICA). By performing the recombination of pixel position, a sequence of phase-shifting interferograms with random phase shifts are decomposed into a group of mutual independent components, and then the background and the measured phase of interferogram can obtained with a simple arctangent operation. Compared with the conventional advanced iterative algorithm (AIA) with high accuracy, both the simulation and the experimental results demonstrate that the proposed ICA algorithm reveals high accuracy, rapid convergence, and good noise-tolerance in random phase-shifting interferometry.

  17. Generalized parametric down conversion, many particle interferometry, and Bell's theorem

    NASA Technical Reports Server (NTRS)

    Choi, Hyung Sup

    1992-01-01

    A new field of multi-particle interferometry is introduced using a nonlinear optical spontaneous parametric down conversion (SPDC) of a photon into more than two photons. The study of SPDC using a realistic Hamiltonian in a multi-mode shows that at least a low conversion rate limit is possible. The down converted field exhibits many stronger nonclassical phenomena than the usual two photon parametric down conversion. Application of the multi-particle interferometry to a recently proposed many particle Bell's theorem on the Einstein-Podolsky-Rosen problem is given.

  18. Determination of Young's modulus of silica aerogels using holographic interferometry

    NASA Astrophysics Data System (ADS)

    Chikode, Prashant P.; Sabale, Sandip R.; Vhatkar, Rajiv S.

    2016-05-01

    Digital holographic interferometry technique is used to determine elastic modulus of silica aerogels. Tetramethoxysilane precursor based Silica aerogels were prepared by the sol-gel process followed by supercritical methanol drying. The alcogels were prepared by keeping the molar ratio of tetramethoxysilane: methyltrimethoxysilane: H2O constant at 1:0.6:4 while the methanol / tetramethoxysilane molar ratio (M) was varied systematically from 12 to 18. Holograms of translucent aerogel samples have been successfully recorded using the digital holographic interferometry technique. Stimulated digital interferograms gives localization of interference fringes on the aerogel surface and these fringes are used to determine the surface deformation and Young's modulus (Y) of the aerogels.

  19. Aberration-free holographic reverse-shearing interferometry

    SciTech Connect

    Lyalikov, A M

    2005-02-28

    The peculiarities of holographic reverse-shearing interferometry, which make it possible to obtain two simultaneous real-time interferograms of the phase object free from aberrations of the optical system are studied. The behaviour of fringes in the interferograms is identical to their behaviour in the conventional two-beam interferometry with a standard reference wave. The peculiarities of fringe alignment in the interferograms are considered. The real-time interferograms of a glass test plate with various fringe alignments are obtained, confirming the practical prospects of this technique. (laser applications and other topics in quantum electronics)

  20. Seismic interferometry of scattered surface waves in attenuative media

    NASA Astrophysics Data System (ADS)

    Halliday, David; Curtis, Andrew

    2009-07-01

    Seismic interferometry can be used to estimate interreceiver surface wave signals by cross-correlation of signals recorded at each receiver that are emitted from a surrounding boundary of impulsive or uncorrelated noise sources. We study seismic interferometry for scattered surface waves using a stationary-phase analysis and surface wave Green's functions for isotropic point scatterers embedded in laterally homogeneous media. Our analysis reveals key differences between the interferometric construction of reflected and point-scattered body or surface waves, since point scatterers radiate energy in all directions but a reflection from a finite flat reflector is specular. In the case of surface waves, we find that additional cancelling terms are introduced in the stationary-phase analysis for scattered waves related to the constraint imposed by the optical theorem for surface waves. The additional terms are of second order even for single-scattered waves, and we show that these can be highly significant in multiple-scattering cases. In attenuative media errors are introduced due to amplitude errors in these additional terms. Further, we find that as the distribution of scatterers in a medium becomes more complex the errors in correlation-type interferometry caused by attenuation in the background medium become larger. Convolution-type interferometry has been shown to be effective when considering electromagnetic wavefields in lossy media, and we show that this is also true for scattered surface waves in attenuating elastic media. By adapting our stationary-phase approach to this case, we reveal why convolution-type interferometry performs well in such media: the second-order cancelling terms that appear in the correlation-type approach do not appear in convolution-type interferometry. Finally, we find that when using both correlation- and convolution-type interferometry with realistic source geometries (illustrative of both industrial seismics and `passive noise

  1. Measuring acoustic habitats

    PubMed Central

    Merchant, Nathan D; Fristrup, Kurt M; Johnson, Mark P; Tyack, Peter L; Witt, Matthew J; Blondel, Philippe; Parks, Susan E

    2015-01-01

    1. Many organisms depend on sound for communication, predator/prey detection and navigation. The acoustic environment can therefore play an important role in ecosystem dynamics and evolution. A growing number of studies are documenting acoustic habitats and their influences on animal development, behaviour, physiology and spatial ecology, which has led to increasing demand for passive acoustic monitoring (PAM) expertise in the life sciences. However, as yet, there has been no synthesis of data processing methods for acoustic habitat monitoring, which presents an unnecessary obstacle to would-be PAM analysts. 2. Here, we review the signal processing techniques needed to produce calibrated measurements of terrestrial and aquatic acoustic habitats. We include a supplemental tutorial and template computer codes in matlab and r, which give detailed guidance on how to produce calibrated spectrograms and statistical analyses of sound levels. Key metrics and terminology for the characterisation of biotic, abiotic and anthropogenic sound are covered, and their application to relevant monitoring scenarios is illustrated through example data sets. To inform study design and hardware selection, we also include an up-to-date overview of terrestrial and aquatic PAM instruments. 3. Monitoring of acoustic habitats at large spatiotemporal scales is becoming possible through recent advances in PAM technology. This will enhance our understanding of the role of sound in the spatial ecology of acoustically sensitive species and inform spatial planning to mitigate the rising influence of anthropogenic noise in these ecosystems. As we demonstrate in this work, progress in these areas will depend upon the application of consistent and appropriate PAM methodologies. PMID:25954500

  2. A new model for film bulk acoustic wave resonators

    NASA Astrophysics Data System (ADS)

    Li, Yu-Jin; Yuan, Xiu-Hua

    2014-11-01

    Based on cavity resonance and sandwich composite plate theory, this paper presents a universal three-dimensional (3D) theoretical model for frequency dispersion characterization and displacement profile shapes of the film bulk acoustic resonator (FBARs). This model provides results of FBAR excited thickness-extensional and flexure modes, and the result of frequency dispersion is proposed in which the thicknesses and impedance of the electrodes and the piezoelectric material are taken into consideration; its further simplification shows good agreement with the modified Butterworth—Van-Dyke (MBVD) model. The displacement profile reflects the vibration stress distribution of electrode shapes and the lateral resonance effect, which depends on the axis ratio of the electrode shapes a/b. The results are consistent with the 3D finite element method modeling and laser interferometry measurement in general.

  3. Acoustic emission monitoring system

    DOEpatents

    Romrell, Delwin M.

    1977-07-05

    Methods and apparatus for identifying the source location of acoustic emissions generated within an acoustically conductive medium. A plurality of acoustic receivers are communicably coupled to the surface of the medium at a corresponding number of spaced locations. The differences in the reception time of the respective sensors in response to a given acoustic event are measured among various sensor combinations prescribed by the monitoring mode employed. Acoustic reception response encountered subsequent to the reception by a predetermined number of the prescribed sensor combinations are inhibited from being communicated to the processing circuitry, while the time measurements obtained from the prescribed sensor combinations are translated into a position measurement representative of the location on the surface most proximate the source of the emission. The apparatus is programmable to function in six separate and five distinct operating modes employing either two, three or four sensory locations. In its preferred arrangement the apparatus of this invention will re-initiate a monitoring interval if the predetermined number of sensors do not respond to a particular emission within a given time period.

  4. Scanning Tomographic Acoustic Microscopy

    NASA Astrophysics Data System (ADS)

    Wade, G.; Meyyappan, A.

    1988-07-01

    The technology for "seeing" with sound has an important and interesting history. Some of nature's creatures have been using sound waves for many millenia to image otherwise unobservable objects. The human species, lacking this natural ability, have overcome this deficiency by developing several different ultrasonic imaging techniques. acoustic microscopy is one such technique, which produces high resolution images of detailed structure of small objects in a non-destructive fashion. Two types of acoustic microscopes have evolved for industrial exploitation. They are the scanning laser acoustic microscope (SLAM) and the scanning acoustic microscope (SAM). In this paper, we review the principles of SLAM and describe how we use elements of SLAM to realize the scanning tomographic acoustic microscope (STAM). We describe the data acquisition process and the image reconstruction procedure. We also describe techniques to obtain projection data from different angles of wave incidence enabling us to reconstruct different planes of a complex specimen tomo-graphically. Our experimental results show that STAM is capable of producing high-quality high-resolution subsurface images.

  5. Tracking changes in volcanic systems with seismic Interferometry

    USGS Publications Warehouse

    Haney, Matt; Alicia J. Hotovec-Ellis; Ninfa L. Bennington; Silvio De Angelis; Clifford Thurber

    2014-01-01

    The detection and evaluation of time-dependent changes at volcanoes form the foundation upon which successful volcano monitoring is built. Temporal changes at volcanoes occur over all time scales and may be obvious (e.g., earthquake swarms) or subtle (e.g., a slow, steady increase in the level of tremor). Some of the most challenging types of time-dependent change to detect are subtle variations in material properties beneath active volcanoes. Although difficult to measure, such changes carry important information about stresses and fluids present within hydrothermal and magmatic systems. These changes are imprinted on seismic waves that propagate through volcanoes. In recent years, there has been a quantum leap in the ability to detect subtle structural changes systematically at volcanoes with seismic waves. The new methodology is based on the idea that useful seismic signals can be generated “at will” from seismic noise. This means signals can be measured any time, in contrast to the often irregular and unpredictable times of earthquakes. With seismic noise in the frequency band 0.1–1 Hz arising from the interaction of the ocean with the solid Earth known as microseisms, researchers have demonstrated that cross-correlations of passive seismic recordings between pairs of seismometers yield coherent signals (Campillo and Paul 2003; Shapiro and Campillo 2004). Based on this principle, coherent signals have been reconstructed from noise recordings in such diverse fields as helioseismology (Rickett and Claerbout 2000), ultrasound (Weaver and Lobkis 2001), ocean acoustic waves (Roux and Kuperman 2004), regional (Shapiro et al. 2005; Sabra et al. 2005; Bensen et al. 2007) and exploration (Draganov et al. 2007) seismology, atmospheric infrasound (Haney 2009), and studies of the cryosphere (Marsan et al. 2012). Initial applications of ambient seismic noise were to regional surface wave tomography (Shapiro et al. 2005). Brenguier et al. (2007) were the first to

  6. Digital Stroboscopic Holography Setup for Deformation Measurement at Both Quasi-Static and Acoustic Frequencies

    NASA Astrophysics Data System (ADS)

    De Greef, Daniël; Soons, Joris; Dirckx, Joris J. J.

    2014-10-01

    A setup for digital stroboscopic holography that combines the advantages of full-field digital holographic interferometry with a high temporal resolution is presented. The setup can be used to identify and visualize complicated vibrational patterns with nanometer amplitudes, ranging from quasi-static to high frequency vibrations. By using a high-energy pulsed laser, single-shot holograms can be recorded and stability issues are avoided. Results are presented for an acoustically stimulated rubber membrane and the technique is evaluated by means of an accuracy and a repeatability test. The presented technique offers wide application possibilities in areas such as biomechanics and industrial testing.

  7. Fiber-optic sensors for acoustic studies and biological applications

    NASA Astrophysics Data System (ADS)

    Zhou, Chonghua

    1997-11-01

    This study is directed at the investigation of the applicability of various fiber-optic techniques in acoustic studies and biological sensing. The acoustic studies are conducted both at low frequencies, such as in audible sound and dynamic wave propagation measurements, and at high frequencies, such as in ultrasound for nondestructive evaluation. In biological sensing, an all- fiber-optic design biosensor with evanescent-mode coupling has been implemented and an enhanced biosensor using ultrasonic localization has been studied. The type of sensor considered for audible sound measurement is based on a combination of Fabry-Perot interferometry and intensity modulation. The technique provides information on both the amplitude and direction of the vibration and thus removes fringe counting ambiguity over a wide dynamic range, and still keeps the high-sensitivity property of interferometry. A novel microbend fiber-optic strain sensor was developed and applied to static and dynamic fracture problems and dynamic wave propagation studies. Static and dynamic fracture experiments and dynamic impact experiment have been performed and the results match well with the theoretical predications and the results obtained with electrical strain gages. The application of polarimetric fiber-optic ultrasonic sensors in nondestructive evaluation of materials is also presented. Theoretical analysis and experimental optimization have been performed and both immersion testing and embedding testing of internal defects of materials have been conducted and promising results have been obtained. For biological application, a compact fiber-optic evanescent-wave sensing system with all-fiber optical design and red semiconductor-laser excitation has been developed and tested. In this system, the fluorescent signal is confined in the fiber system so the signal-to- noise ratio is greatly improved and the sensor can be operated in ambient light conditions. To further enhance this biosensor, an

  8. ACOUSTICS IN ARCHITECTURAL DESIGN, AN ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS.

    ERIC Educational Resources Information Center

    DOELLE, LESLIE L.

    THE PURPOSE OF THIS ANNOTATED BIBLIOGRAPHY ON ARCHITECTURAL ACOUSTICS WAS--(1) TO COMPILE A CLASSIFIED BIBLIOGRAPHY, INCLUDING MOST OF THOSE PUBLICATIONS ON ARCHITECTURAL ACOUSTICS, PUBLISHED IN ENGLISH, FRENCH, AND GERMAN WHICH CAN SUPPLY A USEFUL AND UP-TO-DATE SOURCE OF INFORMATION FOR THOSE ENCOUNTERING ANY ARCHITECTURAL-ACOUSTIC DESIGN…

  9. Acoustic energy shaping

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Elleman, D. D. (Inventor)

    1977-01-01

    A suspended mass is shaped by melting all or a selected portion of the mass and applying acoustic energy in varying amounts to different portions of the mass. In one technique for forming an optical waveguide slug, a mass of oval section is suspended and only a portion along the middle of the cross-section is heated to a largely fluid consistency. Acoustic energy is applied to opposite edges of the oval mass to press the unheated opposite edge portions together so as to form bulges at the middle of the mass. In another technique for forming a ribbon of silicon for constructing solar cells, a cylindrical thread of silicon is drawn from a molten mass of silicon, and acoustic energy is applied to opposite sides of the molten thread to flatten it into a ribbon.

  10. Passive broadband acoustic thermometry

    NASA Astrophysics Data System (ADS)

    Anosov, A. A.; Belyaev, R. V.; Klin'shov, V. V.; Mansfel'd, A. D.; Subochev, P. V.

    2016-04-01

    The 1D internal (core) temperature profiles for the model object (plasticine) and the human hand are reconstructed using the passive acoustothermometric broadband probing data. Thermal acoustic radiation is detected by a broadband (0.8-3.5 MHz) acoustic radiometer. The temperature distribution is reconstructed using a priori information corresponding to the experimental conditions. The temperature distribution for the heated model object is assumed to be monotonic. For the hand, we assume that the temperature distribution satisfies the heat-conduction equation taking into account the blood flow. The average error of reconstruction determined for plasticine from the results of independent temperature measurements is 0.6 K for a measuring time of 25 s. The reconstructed value of the core temperature of the hand (36°C) generally corresponds to physiological data. The obtained results make it possible to use passive broadband acoustic probing for measuring the core temperatures in medical procedures associated with heating of human organism tissues.

  11. Surface Acoustic Wave Microfluidics

    NASA Astrophysics Data System (ADS)

    Yeo, Leslie Y.; Friend, James R.

    2014-01-01

    Fluid manipulations at the microscale and beyond are powerfully enabled through the use of 10-1,000-MHz acoustic waves. A superior alternative in many cases to other microfluidic actuation techniques, such high-frequency acoustics is almost universally produced by surface acoustic wave devices that employ electromechanical transduction in wafer-scale or thin-film piezoelectric media to generate the kinetic energy needed to transport and manipulate fluids placed in adjacent microfluidic structures. These waves are responsible for a diverse range of complex fluid transport phenomena - from interfacial fluid vibration and drop and confined fluid transport to jetting and atomization - underlying a flourishing research literature spanning fundamental fluid physics to chip-scale engineering applications. We highlight some of this literature to provide the reader with a historical basis, routes for more detailed study, and an impression of the field's future directions.

  12. Latticed pentamode acoustic cloak

    PubMed Central

    Chen, Yi; Liu, Xiaoning; Hu, Gengkai

    2015-01-01

    We report in this work a practical design of pentamode acoustic cloak with microstructure. The proposed cloak is assembled by pentamode lattice made of a single-phase solid material. The function of rerouting acoustic wave round an obstacle has been demonstrated numerically. It is also revealed that shear related resonance due to weak shear resistance in practical pentamode lattices punctures broadband feature predicted based on ideal pentamode cloak. As a consequence, the latticed pentamode cloak can only conceal the obstacle in segmented frequency ranges. We have also shown that the shear resonance can be largely reduced by introducing material damping, and an improved broadband performance can be achieved. These works pave the way for experimental demonstration of pentamode acoustic cloak. PMID:26503821

  13. Seamount acoustic scattering

    NASA Astrophysics Data System (ADS)

    Boehlert, George W.

    The cover of the March 1 issue of Eos showed a time series of acoustic scattering above Southeast Hancock Seamount (29°48‧N, 178°05‧E) on July 17-18, 1984. In a comment on that cover Martin Hovland (Eos, August 2, p. 760) argued that gas or “other far reaching causes” may be involved in the observed acoustic signals. He favors a hypothesis that acoustic scattering observed above a seeping pockmark in the North Sea is a combination of bubbles, stable microbubbles, and pelagic organisms and infers that this may be a more general phenomenon and indeed plays a role in the attraction of organisms to seamounts

  14. A New Wave of Acoustics.

    ERIC Educational Resources Information Center

    Beyer, Robert

    1981-01-01

    Surveys 50 years of acoustical studies by discussing selected topics including the ear, nonlinear representations, underwater sound, acoustical diagnostics, absorption, electrolytes, phonons, magnetic interaction, and superfluidity and the five sounds. (JN)

  15. A new polarized neutron interferometry facility at the NCNR

    NASA Astrophysics Data System (ADS)

    Shahi, C. B.; Arif, M.; Cory, D. G.; Mineeva, T.; Nsofini, J.; Sarenac, D.; Williams, C. J.; Huber, M. G.; Pushin, D. A.

    2016-03-01

    A new monochromatic beamline and facility has been installed at the National Institute of Standards and Technology (NIST) Center for Neutron Research (NCNR) devoted to neutron interferometry in the research areas of spin control, spin manipulation, quantum mechanics, quantum information science, spintronics, and material science. This facility is possible in part because of advances in decoherence free subspace interferometer designs that have demonstrated consistent contrast in the presence of vibrational noise; a major environmental constraint that has prevented neutron interferometry from being applied at other neutron facilities. Neutron interferometry measures the phase difference between a neutron wave function propagating along two spatially separated paths. It is a practical example of self interference and due to its modest path separation of a few centimeters allows the insertion of samples and macroscopic neutron spin rotators. Phase shifts can be caused by gravitational, magnetic and nuclear interactions as well as purely quantum mechanical effects making interferometer a robust tool in neutron research. This new facility is located in the guide hall of the NCNR upstream of the existing Neutron Interferometry and Optics Facility (NIOF) and has several advantages over the NIOF including higher incident flux, better neutron polarization, and increased accessibility. The long term goal for the new facility is to be a user supported beamline and makes neutron interferometer more generally available to the scientific community. This paper addresses both the capabilities and characteristics of the new facility.

  16. Mask Design for the Space Interferometry Mission Internal Metrology

    NASA Technical Reports Server (NTRS)

    Marx, David; Zhao, Feng; Korechoff, Robert

    2005-01-01

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

  17. Speckle interferometry applied to asteroids and other solar system objects

    NASA Technical Reports Server (NTRS)

    Drummond, J. D.; Hege, E. K.

    1985-01-01

    The application of speckle interferometry to asteroids and other solar system objects is discussed. The assumption of a triaxial ellipsoid rotating about its shortest axis is the standard model. Binary asteroids, 433 Eros, 532 Herculina, 511 Davida, and Pallas are discussed.

  18. Distinguishing between Dirac and Majorana neutrinos withtwo-particle interferometry

    SciTech Connect

    Gutierrez, Thomas D.

    2006-03-02

    Two-particle interferometry, a second-order interferenceeffect, is explored as another possible tool to distinguish betweenmassive Dirac and Majorana neutrinos. A simple theoretical framework isdiscussed in the context of several gedanken experiments. The method canin principle provide both the mass scale and the quantum nature of theneutrino for a certain class of incoherent left-handed sourcecurrents.

  19. How to Test Atom and Neutron Neutrality with Atom Interferometry

    SciTech Connect

    Arvanitaki, Asimina; Dimopoulos, Savas; Geraci, Andrew A.; Hogan, Jason; Kasevich, Mark

    2008-03-28

    We propose an atom-interferometry experiment based on the scalar Aharonov-Bohm effect which detects an atom charge at the 10{sup -28}e level, and improves the current laboratory limits by 8 orders of magnitude. This setup independently probes neutron charges down to 10{sup -28}e, 7 orders of magnitude below current bounds.

  20. How to test atom and neutron neutrality with atom interferometry.

    PubMed

    Arvanitaki, Asimina; Dimopoulos, Savas; Geraci, Andrew A; Hogan, Jason; Kasevich, Mark

    2008-03-28

    We propose an atom-interferometry experiment based on the scalar Aharonov-Bohm effect which detects an atom charge at the 10{-28}e level, and improves the current laboratory limits by 8 orders of magnitude. This setup independently probes neutron charges down to 10{-28}e, 7 orders of magnitude below current bounds. PMID:18517846

  1. Results of 1993 Repeat-Pass SAR Interferometry Experiments

    NASA Technical Reports Server (NTRS)

    Klein, J. D.; Hensley, S.; Madsen, S. N.; Webb, F. H.

    1994-01-01

    In this talk we present results of a repeat-pass SAR interferometry experiment performed in June 1993 near Portage, Maine. Differential GPS data accurate to +/-10cm were acquired to aid in motion compensation and geolocation of targets in the imagery. The experiment and data analysis will be discussed, and results will be shown during the presentation.

  2. Digital holographic interferometry for measurement of temperature in axisymmetric flames.

    PubMed

    Sharma, Shobhna; Sheoran, Gyanendra; Shakher, Chandra

    2012-06-01

    In this paper, experimental investigations and analysis is presented to measure the temperature and temperature profile of gaseous flames using lensless Fourier transform digital holographic interferometry. The evaluations of the experimental results give the accuracy, sensitivity, spatial resolution, and range of measurements to be well within the experimental limits. Details of the experimental results and analysis are presented. PMID:22695554

  3. Waveguide Zeeman interferometry for thin-film chemical sensors

    SciTech Connect

    Grace, K.M.; Shrouf, K.; Johnston, R.G.; Yang, X.; Swanson, B.; Honkanen, S.; Ayras, P.; Peyghambarian, N.; Katila, P.; Leppihalme, M.

    1997-10-01

    A chemical sensor is demonstrated which is based on Si{sub 3}N{sub 4} optical waveguides coated with species-selective thin films and using Zeeman interferometry as the detection technique. Relative phase change between TE and TM modes is measured. Real time and reversible response to toluene is shown with ppm level sensitivity.

  4. The Compact and Inexpensive "Arrowhead" Setup for Holographic Interferometry

    ERIC Educational Resources Information Center

    Ladera, Celso L.; Donoso, Guillermo

    2011-01-01

    Hologram recording and holographic interferometry are intrinsically sensitive to phase changes, and therefore both are easily perturbed by minuscule optical path perturbations. It is therefore very convenient to bank on holographic setups with a reduced number of optical components. Here we present a compact off-axis holographic setup that…

  5. Testing Atom and Neutron Neutrality with Atom Interferometry

    SciTech Connect

    Arvanitaki, Asimina; Dimopoulos, Savas; Geraci, Andrew A.; Hogan, Jason; Kasevich, Mark; /Stanford U., Phys. Dept.

    2008-01-07

    We propose an atom-interferometry experiment based on the scalar Aharonov-Bohm effect which detects an atom charge at the 10{sup -28} e level, and improves the current laboratory limits by 8 orders of magnitude. This setup independently probes neutron charges down to 10{sup 28} e, 7 orders of magnitude below current bounds.

  6. Kitt Peak Speckle Interferometry of Close Visual Binary Stars (Abstract)

    NASA Astrophysics Data System (ADS)

    Gener, R.; Rowe, D.; Smith, T. C.; Teiche, A.; Harshaw, R.; Wallace, D.; Weise, E.; Wiley, E.; Boyce, G.; Boyce, P.; Branston, D.; Chaney, K.; Clark, R. K.; Estrada, C.; Estrada, R.; Frey, T.; Green, W. L.; Haurberg, N.; Jones, G.; Kenney, J.; Loftin, S.; McGieson, I.; Patel, R.; Plummer, J.; Ridgely, J.; Trueblood, M.; Westergren, D.; Wren, P.

    2014-12-01

    (Abstract only) Speckle interferometry can be used to overcome normal seeing limitations by taking many very short exposures at high magnification and analyzing the resulting speckles to obtain the position angles and separations of close binary stars. A typical speckle observation of a close binary consists of 1,000 images, each 20 milliseconds in duration. The images are stored as a multi-plane FITS cube. A portable speckle interferometry system that features an electron-multiplying CCD camera was used by the authors during two week-long observing runs on the 2.1-meter telescope at Kitt Peak National Observatory to obtain some 1,000 data cubes of close binaries selected from a dozen different research programs. Many hundreds of single reference stars were also observed and used in deconvolution to remove undesirable atmospheric and telescope optical effects. The database of well over one million images was reduced with the Speckle Interferometry Tool of platesolve3. A few sample results are provided. During the second Kitt Peak run, the McMath-Pierce 1.6- and 0.8-meter solar telescopes were evaluated for nighttime speckle interferometry, while the 0.8-meter Coude feed was used to obtain differential radial velocities of short arc binaries.

  7. Probing Non-Abelian Statistics with Quasiparticle Interferometry

    SciTech Connect

    Bonderson, Parsa; Shtengel, Kirill; Slingerland, J.K.

    2006-07-07

    We examine interferometric experiments in systems that exhibit non-Abelian braiding statistics, expressing outcomes in terms of the modular S-matrix. In particular, this result applies to fractional quantum Hall interferometry, and we give a detailed treatment of the Read-Rezayi states, providing explicit predictions for the recently observed {nu}=12/5 plateau.

  8. A primary standard for low-g shock calibration by laser interferometry

    NASA Astrophysics Data System (ADS)

    Sun, Qiao; Wang, Jian-lin; Hu, Hong-bo

    2014-07-01

    This paper presents a novel implementation of a primary standard for low-g shock acceleration calibration by laser interferometry based on rigid body collision at National Institute of Metrology, China. The mechanical structure of the standard device and working principles involved in the shock acceleration exciter, laser interferometers and virtual instruments are described. The novel combination of an electromagnetic exciter and a pneumatic exciter as the mechanical power supply of the standard device can deliver a wide range of shock acceleration levels. In addition to polyurethane rubber, two other types of material are investigated to ensure a wide selection of cushioning pads for shock pulse generation, with pulse shapes and data displayed. A heterodyne He-Ne laser interferometer is preferred for its precise and reliable measurement of shock acceleration while a homodyne one serves as a check standard. Some calibration results of a standard acceleration measuring chain are shown in company with the uncertainty evaluation budget. The expanded calibration uncertainty of shock sensitivity of the acceleration measuring chain is 0.8%, k = 2, with the peak acceleration range from 20 to 10 000 m s-2 and pulse duration from 0.5 to 10 ms. This primary shock standard can meet the traceability requirements of shock acceleration from various applications of industries from automobile to civil engineering and therefore is used for piloting the ongoing shock comparison of Technical Committee of Acoustics, Ultrasound and Vibration (TCAUV) of Asia Pacific Metrology Program (APMP), coded as APMP.AUV.V-P1.

  9. Laboratory coda wave interferometry for the monitoring of rock property variations

    NASA Astrophysics Data System (ADS)

    Schmittbuhl, Jean; Chaintreuil, Marie; Lengliné, Olivier; Griffiths, Luke; Heap, Mike; Baud, Patrick

    2016-04-01

    A significant effort is on-going in the community to continuously monitor deep geothermal reservoirs using ambient seismic noise tomography (e.g. Calo et al, 2013; Lehujeur et al, 2015). It is a method that determines the Green's function between a pair of receivers by correlating sufficiently long seismic noise records. Very small changes of the medium are accessible using this new monitoring technique (significantly smaller than those deduced from direct arrivals). In particular, very small variations of seismic velocities are shown to appear both in time and space during the stimulation of the reservoir. A central question is how to interpret these transient or lateral variations of the seismic velocities for a precise 4D tomography of the reservoir properties. In this study, we address the direct problem of monitoring small variations in seismic velocities when small variations in stress or temperature are slowly applied to the sample. We use a network of piezo-electric sensors on laboratory samples (sandstone and granite from Soultz-sous-Forêts core samples) to perform coda wave interferometry from the multiple scattering of well-controlled seismic pulses (Grêt et al, 2006). The data collected are estimates of the relative variation of travel time. We combine acoustic measurements and strain gauges to differentiate between travel time variations due to seismic velocity changes and those due to deformation effects. We expect this approach to provide useful information for large scale seismic tomography despite the significant difference of considered wavelengths.

  10. Densitometry By Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Trinh, Eugene H.

    1989-01-01

    "Static" and "dynamic" methods developed for measuring mass density of acoustically levitated solid particle or liquid drop. "Static" method, unknown density of sample found by comparison with another sample of known density. "Dynamic" method practiced with or without gravitational field. Advantages over conventional density-measuring techniques: sample does not have to make contact with container or other solid surface, size and shape of samples do not affect measurement significantly, sound field does not have to be know in detail, and sample can be smaller than microliter. Detailed knowledge of acoustic field not necessary.

  11. Acoustic tooth cleaner

    NASA Technical Reports Server (NTRS)

    Heyman, J. S. (Inventor)

    1982-01-01

    An acoustic oral hygiene unit is described that uses acoustic energy to oscillate mild abrasive particles in a water suspension which is then directed in a low pressure stream onto the teeth. The oscillating abrasives scrub the teeth clean removing food particles, plaque, calculous, and other foreign material from tooth surfaces, interproximal areas, and tooth-gingiva interface more effectively than any previous technique. The relatively low power output and the basic design makes the invention safe and convenient for everyday use in the home without special training. This invention replaces all former means of home dental prophylaxis, and requires no augmentation to fulfill all requirements for daily oral hygienic care.

  12. Acoustic emission intrusion detector

    DOEpatents

    Carver, Donald W.; Whittaker, Jerry W.

    1980-01-01

    An intrusion detector is provided for detecting a forcible entry into a secured structure while minimizing false alarms. The detector uses a piezoelectric crystal transducer to sense acoustic emissions. The transducer output is amplified by a selectable gain amplifier to control the sensitivity. The rectified output of the amplifier is applied to a Schmitt trigger circuit having a preselected threshold level to provide amplitude discrimination. Timing circuitry is provided which is activated by successive pulses from the Schmitt trigger which lie within a selected time frame for frequency discrimination. Detected signals having proper amplitude and frequency trigger an alarm within the first complete cycle time of a detected acoustical disturbance signal.

  13. Strong acoustic wave action

    NASA Astrophysics Data System (ADS)

    Gokhberg, M. B.

    1983-07-01

    Experiments devoted to acoustic action on the atmosphere-magnetosphere-ionosphere system using ground based strong explosions are reviewed. The propagation of acoustic waves was observed by ground observations over 2000 km in horizontal direction and to an altitude of 200 km. Magnetic variations up to 100 nT were detected by ARIEL-3 satellite near the epicenter of the explosion connected with the formation of strong field aligned currents in the magnetosphere. The enhancement of VLF emission at 800 km altitude is observed.

  14. Acoustic bubble removal method

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Elleman, D. D.; Wang, T. G. (Inventor)

    1983-01-01

    A method is described for removing bubbles from a liquid bath such as a bath of molten glass to be used for optical elements. Larger bubbles are first removed by applying acoustic energy resonant to a bath dimension to drive the larger bubbles toward a pressure well where the bubbles can coalesce and then be more easily removed. Thereafter, submillimeter bubbles are removed by applying acoustic energy of frequencies resonant to the small bubbles to oscillate them and thereby stir liquid immediately about the bubbles to facilitate their breakup and absorption into the liquid.

  15. Acoustic and electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Jones, Douglas Samuel

    Theoretical models of EM and acoustic wave propagation are presented in an introductory text intended for intermediate-level science and engineering students. Chapters are devoted to the mathematical representation of acoustic and EM fields, the special theory of relativity, radiation, resonators, waveguide theory, refraction, surface waves, scattering by smooth objects, diffraction by edges, and transient waves. The mathematical tools required for the analysis (Bessel, Legendre, Mathieu, parabolic-cylinder, and spheroidal functions; tensor calculus; and the asymptotic evaluation of integrals) are covered in appendices.

  16. Structural Acoustics and Vibrations

    NASA Astrophysics Data System (ADS)

    Chaigne, Antoine

    This chapter is devoted to vibrations of structures and to their coupling with the acoustic field. Depending on the context, the radiated sound can be judged as desirable, as is mostly the case for musical instruments, or undesirable, like noise generated by machinery. In architectural acoustics, one main goal is to limit the transmission of sound through walls. In the automobile industry, the engineers have to control the noise generated inside and outside the passenger compartment. This can be achieved by means of passive or active damping. In general, there is a strong need for quieter products and better sound quality generated by the structures in our daily environment.

  17. Electromechanical acoustic liner

    NASA Technical Reports Server (NTRS)

    Sheplak, Mark (Inventor); Cattafesta, III, Louis N. (Inventor); Nishida, Toshikazu (Inventor); Horowitz, Stephen Brian (Inventor)

    2007-01-01

    A multi-resonator-based system responsive to acoustic waves includes at least two resonators, each including a bottom plate, side walls secured to the bottom plate, and a top plate disposed on top of the side walls. The top plate includes an orifice so that a portion of an incident acoustical wave compresses gas in the resonators. The bottom plate or the side walls include at least one compliant portion. A reciprocal electromechanical transducer coupled to the compliant portion of each of the resonators forms a first and second transducer/compliant composite. An electrical network is disposed between the reciprocal electromechanical transducer of the first and second resonator.

  18. Acoustic loading in straight pipes

    NASA Technical Reports Server (NTRS)

    El-Raheb, M.

    1980-01-01

    Based on linear one-dimensional acoustics, a geometrically perfect elastic waveguide would respond to an oscillatory internal pressure only in the presence of path deflectors (elbows and branches). In practice, a significant elasto-acoustic interaction results even in straight conduits as a result of manufacturing tolerances. A theoretical model of the linear acoustic loading in straight pipes is developed that considers the acoustic wave distortion due to perimeter, axial, and wall thickness nonuniformities.

  19. Spacecraft Internal Acoustic Environment Modeling

    NASA Technical Reports Server (NTRS)

    Allen, Christopher; Chu, S. Reynold

    2008-01-01

    The objective of the project is to develop an acoustic modeling capability, based on commercial off-the-shelf software, to be used as a tool for oversight of the future manned Constellation vehicles to ensure compliance with acoustic requirements and thus provide a safe and habitable acoustic environment for the crews, and to validate developed models via building physical mockups and conducting acoustic measurements.

  20. Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.

    2009-01-01

    Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in

  1. Variable-Position Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Stoneburner, J. D.; Jacobi, N.; Wang, T. G.

    1983-01-01

    Method of acoustic levitation supports objects at positions other than acoustic nodes. Acoustic force is varied so it balances gravitational (or other) force, thereby maintaining object at any position within equilibrium range. Levitation method applicable to containerless processing. Such objects as table-tennis balls, hollow plastic spheres, and balsa-wood spheres levitated in laboratory by new method.

  2. Acoustical Environment of School Buildings.

    ERIC Educational Resources Information Center

    Fitzroy, Dariel; Reid, John L.

    A field study was made of the acoustical environment of schools designed for increased flexibility to meet the spatial requirements of new teaching methods. The object of the study was to define all the criteria for the acoustical design of this type of classroom including the determination of--(1) minimum acoustical separation required for…

  3. ACOUSTICAL ENVIRONMENT OF SCHOOL BUILDINGS.

    ERIC Educational Resources Information Center

    FITZROY, DARIEL; REID, JOHN L.

    A FIELD STUDY WAS MADE OF THE ACOUSTICAL ENVIRONMENT OF SCHOOLS DESIGNED FOR INCREASED FLEXIBILITY TO MEET THE SPATIAL REQUIREMENTS OF NEW TEACHING METHODS. THE OBJECT OF THE STUDY WAS TO DEFINE ALL THE CRITERIA FOR THE ACOUSTICAL DESIGN OF THIS TYPE OF CLASSROOM INCLUDING THE DETERMINATION OF--(1) MINIMUM ACOUSTICAL SEPARATION REQUIRED FOR…

  4. Post Treatment of Acoustic Neuroma

    MedlinePlus

    Home What is an AN What is an Acoustic Neuroma? Identifying an AN Symptoms Acoustic Neuroma Keywords Educational Video Pre-Treatment Treatment Options Summary Treatment Options Watch and Wait Radiation Microsurgery Acoustic Neuroma Decision Tree Questions for Your Physician Questions ...

  5. Application of Seismic Interferometry to Natural Earthquake Records

    NASA Astrophysics Data System (ADS)

    Torii, K.; Matsuoka, T.; Aizawa, T.

    2007-12-01

    Recently, seismic interferometry has been one of the hottest topics in the exploration geophysics since this can be applied to reflection seismology. Seismic interferometry constructs Green's functions between arbitrary two points by taking cross-correlation of records observed at two locations. These Green's functions correspond to the wavefields as if an impulsive source was set at one location and seismic wave propagates from this source to the other receiver. Therefore, if we chose two surface receivers, we can reconstruct reflection seismic data. In case of using many receivers in a survey line, taking cross-correlation of all observed data at receivers generates pseudo shot-gather data for arbitrary locations. This technique does not need information of time 0 as long as all receivers measure wavefields synchronously. Therefore, there is no limitation with regard to the cause of the seismic vibrations. Natural earthquakes may be very good seismic sources for seismic interferometry. In our study, we adopt data provided by Hi-net system for applications of seismic interferometry. In 1995, 'The Great Hanshin Earthquake' struck around Osaka and Kobe in Japan. After that, Japanese Government decided to construct high-density and high-sensitivity sensor network all over Japan in order to accumulate effective information of earthquakes and understand the mechanism of earthquakes. This seismic network is called 'Hi- net system' in Japan. Hi-net system provides us much effective information, origin time, epicenter, depth, magnitude and waveform, etc... We used waveforms provided by Hi-net and generated pseudo shot-gather data by using seismic interferometry. Then, we applied these data to conventional reflection survey and analyzed underground structures in Japan.

  6. Fundamentals of Acoustics. Psychoacoustics and Hearing. Acoustical Measurements

    NASA Technical Reports Server (NTRS)

    Begault, Durand R.; Ahumada, Al (Technical Monitor)

    1997-01-01

    These are 3 chapters that will appear in a book titled "Building Acoustical Design", edited by Charles Salter. They are designed to introduce the reader to fundamental concepts of acoustics, particularly as they relate to the built environment. "Fundamentals of Acoustics" reviews basic concepts of sound waveform frequency, pressure, and phase. "Psychoacoustics and Hearing" discusses the human interpretation sound pressure as loudness, particularly as a function of frequency. "Acoustic Measurements" gives a simple overview of the time and frequency weightings for sound pressure measurements that are used in acoustical work.

  7. Acoustic subwavelength imaging of subsurface objects with acoustic resonant metalens

    SciTech Connect

    Cheng, Ying; Liu, XiaoJun; Zhou, Chen; Wei, Qi; Wu, DaJian

    2013-11-25

    Early research into acoustic metamaterials has shown the possibility of achieving subwavelength near-field acoustic imaging. However, a major restriction of acoustic metamaterials is that the imaging objects must be placed in close vicinity of the devices. Here, we present an approach for acoustic imaging of subsurface objects far below the diffraction limit. An acoustic metalens made of holey-structured metamaterials is used to magnify evanescent waves, which can rebuild an image at the central plane. Without changing the physical structure of the metalens, our proposed approach can image objects located at certain distances from the input surface, which provides subsurface signatures of the objects with subwavelength spatial resolution.

  8. Microfiber interferometric acoustic transducers.

    PubMed

    Wang, Xiuxin; Jin, Long; Li, Jie; Ran, Yang; Guan, Bai-Ou

    2014-04-01

    Acoustic and ultrasonic transducers are key components in biomedical information technology, which has been applied in medical diagnosis, photoacoustic endoscopy and photoacoustic imaging. In this paper, an acoustic transducer based on Fabry-Perot interferometer (FPI) fabricated in a microscaled optical fiber is demonstrated. The transducer is fabricated by forming two wavelength-matched Bragg gratings into the microfiber by means of side illumination with a 193nm excimer laser. When placing the transducer in water, the applied acoustic signal periodically changes the refractive index (RI) of the surrounding liquid and modulates the transmission of the FPI based on the evanescent-field interaction between the liquid and the transmitting light. As a result, the acoustic signal can be constructed with a tunable laser whose output wavelength is located at the slope of the inteferometric fringes. The transducer presents a sensitivity of 10 times higher than the counterparts fabricated in conventional singlemode fibers and has great potential to achieve higher resolution for photoacoustic imaging due to its reduced diameter. PMID:24718189

  9. Intelligent Engine Systems: Acoustics

    NASA Technical Reports Server (NTRS)

    Wojno, John; Martens, Steve; Simpson, Benjamin

    2008-01-01

    An extensive study of new fan exhaust nozzle technologies was performed. Three new uniform chevron nozzles were designed, based on extensive CFD analysis. Two new azimuthally varying variants were defined. All five were tested, along with two existing nozzles, on a representative model-scale, medium BPR exhaust nozzle. Substantial acoustic benefits were obtained from the uniform chevron nozzle designs, the best benefit being provided by an existing design. However, one of the azimuthally varying nozzle designs exhibited even better performance than any of the uniform chevron nozzles. In addition to the fan chevron nozzles, a new technology was demonstrated, using devices that enhance mixing when applied to an exhaust nozzle. The acoustic benefits from these devices applied to medium BPR nozzles were similar, and in some cases superior to, those obtained from conventional uniform chevron nozzles. However, none of the low noise technologies provided equivalent acoustic benefits on a model-scale high BPR exhaust nozzle, similar to current large commercial applications. New technologies must be identified to improve the acoustics of state-of-the-art high BPR jet engines.

  10. Acoustics in Schools.

    ERIC Educational Resources Information Center

    Singer, Miriam J.

    This paper explores the issues associated with poor acoustics within schools. Additionally, it suggests remedies for existing buildings and those under renovation, as well as concerns for new construction. The paper discusses the effects of unwanted noise on students in terms of physiological, motivational, and cognitive influences. Issues are…

  11. Teaching acoustics online

    NASA Astrophysics Data System (ADS)

    Morrison, Andrew; Rossing, Thomas D.

    2003-10-01

    We teach an introductory course in musical acoustics using a Blackboard. Students in this course can access audio and video materials as well as printed materials on our course website. All homework is submitted online, as are tests and examinations. The students also have the opportunity to use synchronous and asynchronous chat rooms to discuss the course with each other or with the instructors.

  12. Micro acoustic spectrum analyzer

    DOEpatents

    Schubert, W. Kent; Butler, Michael A.; Adkins, Douglas R.; Anderson, Larry F.

    2004-11-23

    A micro acoustic spectrum analyzer for determining the frequency components of a fluctuating sound signal comprises a microphone to pick up the fluctuating sound signal and produce an alternating current electrical signal; at least one microfabricated resonator, each resonator having a different resonant frequency, that vibrate in response to the alternating current electrical signal; and at least one detector to detect the vibration of the microfabricated resonators. The micro acoustic spectrum analyzer can further comprise a mixer to mix a reference signal with the alternating current electrical signal from the microphone to shift the frequency spectrum to a frequency range that is a better matched to the resonant frequencies of the microfabricated resonators. The micro acoustic spectrum analyzer can be designed specifically for portability, size, cost, accuracy, speed, power requirements, and use in a harsh environment. The micro acoustic spectrum analyzer is particularly suited for applications where size, accessibility, and power requirements are limited, such as the monitoring of industrial equipment and processes, detection of security intrusions, or evaluation of military threats.

  13. COMBUSTION ACOUSTICS DIAGNOSTICS

    EPA Science Inventory

    This is an Exploratory Research Project that was awarded by APPCD for research on developing an acoustic flame condition monitor. It will involve a bench scale experiment of 4-6 weeks duration to record adjacent audible energy of a Bunsen burner. The experiment will require a d...

  14. Acoustics- Version 1.0

    SciTech Connect

    2012-09-13

    This package contains modules that model acoustic sensors and acoustic sources (hearable) in Umbra. It is typically used to represent hearing in characters within Umbra. Typically, the acoustic sensors detect acoustic sources at a given point; however, it also contains the capability to detect bullet cracks by detecting the sound along the bullet path that is closest to the sensor. A memory module, acoustic memory, represents remembered sounds within a given character. Over time, the sounds are removed, as a character forgets what it has heard.

  15. Acoustics- Version 1.0

    2012-09-13

    This package contains modules that model acoustic sensors and acoustic sources (hearable) in Umbra. It is typically used to represent hearing in characters within Umbra. Typically, the acoustic sensors detect acoustic sources at a given point; however, it also contains the capability to detect bullet cracks by detecting the sound along the bullet path that is closest to the sensor. A memory module, acoustic memory, represents remembered sounds within a given character. Over time, themore » sounds are removed, as a character forgets what it has heard.« less

  16. Acoustical studies of the steelpan and HANG: Phase-sensitive holography and sound intensity measurements

    NASA Astrophysics Data System (ADS)

    Morrison, Andrew C. H.

    The Caribbean steelpan and an instrument closely related, the HANG, are two of the most, interesting acoustic musical instruments developed in the last century. Although simple in design, the acoustic properties of the steelpan and HANG are surprisingly complicated. Holographic interferometry was used to determine the resonances of a low tenor steelpan and a pentatonic HANG. Placement of a vibrating mirror in the optical path of the reference beam expands the capabilities of the holography system to include phase measurements. Phase maps and phase response curves of several low resonances of notes on a steelpan and HANG are shown. Sound intensity measurements were acquired to explore the relationship between the resonances and the radiated sound field. The instruments were placed in an anechoic chamber, and selected notes were excited electromagnetically with a swept sinusoid signal. A two-microphone probe was used to gather sound intensity measurements. Sound intensity reaps of the first three harmonics are shown for notes on both instruments.

  17. Verification of time-delay interferometry techniques using the University of Florida LISA interferometry simulator

    NASA Astrophysics Data System (ADS)

    Mitryk, Shawn J.; Wand, Vinzenz; Mueller, Guido

    2010-04-01

    Laser Interferometer Space Antenna (LISA) is a cooperative NASA/ESA mission proposed to directly measure gravitational waves (GW) in the frequency range from 30 \\,\\mu \\rm {Hz} to 1\\,\\rm {Hz} with an optimal strain sensitivity of 10^{-21}/\\sqrt{Hz} at 3\\,\\rm {mHz}. LISA will utilize a modified Michelson interferometer to measure length changes of 40\\,\\rm {pm}/\\sqrt{Hz} between drag-free proof masses located on three separate spacecraft (SC) separated by a distance of 5\\,\\rm {Gm}. The University of Florida has developed a hardware-in-the-loop simulator of the LISA constellation to verify the laser noise cancellation technique known as time-delay interferometry (TDI). We replicate the frequency stabilization of the laser on the local SC and the phase-locking of the lasers on the far SC. The laser photodetector beatnotes are electronically delayed, Doppler shifted and applied with a mock GW signal to simulate the laser link between the SC. The beatnotes are also measured with a LISA-like phasemeter and the data are used to extract the laser phase and residual phase-lock loop noise in post-processing through TDI. This uncovers the GW modulation signal buried under the laser noise. The results are then compared to the requirements defined by the LISA science collaboration.

  18. Acoustic Suppression Systems and Related Methods

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R. (Inventor); Kern, Dennis L. (Inventor)

    2013-01-01

    An acoustic suppression system for absorbing and/or scattering acoustic energy comprising a plurality of acoustic targets in a containment is described, the acoustic targets configured to have resonance frequencies allowing the targets to be excited by incoming acoustic waves, the resonance frequencies being adjustable to suppress acoustic energy in a set frequency range. Methods for fabricating and implementing the acoustic suppression system are also provided.

  19. Photofragmentation Beam Splitters for Matter-Wave Interferometry

    NASA Astrophysics Data System (ADS)

    Dörre, Nadine; Rodewald, Jonas; Geyer, Philipp; von Issendorff, Bernd; Haslinger, Philipp; Arndt, Markus

    2014-12-01

    Extending the range of quantum interferometry to a wider class of composite nanoparticles requires new tools to diffract matter waves. Recently, pulsed photoionization light gratings have demonstrated their suitability for high mass matter-wave physics. Here, we extend quantum interference experiments to a new class of particles by introducing photofragmentation beam splitters into time-domain matter-wave interferometry. We present data that demonstrate this coherent beam splitting mechanism with clusters of hexafluorobenzene and we show single-photon depletion gratings based both on fragmentation and ionization for clusters of vanillin. We propose that photofragmentation gratings can act on a large set of van der Waals clusters and biomolecules which are thermally unstable and often resilient to single-photon ionization.

  20. The Balloon Experimental Twin Telescope for Infrared Interferometry

    NASA Technical Reports Server (NTRS)

    Rinehart, Stephen A.

    2008-01-01

    Astronomical studies at infrared wavelengths have dramatically improved our understanding of the universe, and observations with Spitzer, the upcoming Herschel mission, and SOFIA will continue to provide exciting new discoveries. The relatively low angular resolution of these missions, however, is insufficient to resolve the physical scales on which mid- to far-infrared emission arises, resulting in source and structure ambiguities that limit our ability to answer key science questions. Interferometry enables high angular resolution at these wavelengths, a powerful tool for scientific discovery, We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETII), an eight-meter baseline Michelson stellar interferometer to fly on a high-altitude balloon. BETTII's spectral-spatial capability, provided by an instrument using double-Fourier techniques, will address key questions about the nature of disks in young star clusters and active galactic nuclei and the envelopes of evolved stars. BETTII will also lay the technological groundwork for future space interferometers,

  1. Deformations and strains in adhesive joints by moire interferometry

    NASA Technical Reports Server (NTRS)

    Post, D.; Czarnek, R.; Wood, J.; John, D.; Lubowinski, S.

    1984-01-01

    Displacement fields in a thick adherend lap joint and a cracked lap shear specimen were measured by high sensitivity moire interferometry. Contour maps of in-plane U and V displacements were obtained across adhesive and adherent surfaces. Loading sequences ranged from modest loads to near-failure loads. Quantitative results are given for displacements and certain strains in the adhesive and along the adhesive/adherend boundary lines. The results show nonlinear displacements and strains as a function of loads or stresses and they show viscoelastic or time-dependent response. Moire interferometry is an excellent method for experimental studies of adhesive joint performance. Subwavelength displacement resolution of a few micro-inches, and spatial resolution corresponding to 1600 fringes/inch (64 fringes/mm), were obtained in these studies. The whole-field contour maps offer insights not available from local measurements made by high sensitivity gages.

  2. Dual-wavelength laser source for onboard atom interferometry.

    PubMed

    Ménoret, V; Geiger, R; Stern, G; Zahzam, N; Battelier, B; Bresson, A; Landragin, A; Bouyer, P

    2011-11-01

    We present a compact and stable dual-wavelength laser source for onboard atom interferometry with two different atomic species. It is based on frequency-doubled telecom lasers locked on a femtosecond optical frequency comb. We take advantage of the maturity of fiber telecom technology to reduce the number of free-space optical components, which are intrinsically less stable, and to make the setup immune to vibrations and thermal fluctuations. The source provides the frequency agility and phase stability required for atom interferometry and can easily be adapted to other cold atom experiments. We have shown its robustness by achieving the first dual-species K-Rb magneto-optical trap in microgravity during parabolic flights. PMID:22048340

  3. Homodyne digital interferometry for a sensitive fiber frequency reference.

    PubMed

    Ngo, Silvie; McRae, Terry G; Gray, Malcolm B; Shaddock, Daniel A

    2014-07-28

    Digitally enhanced homodyne interferometry enables robust interferometric sensitivity to be achieved in an optically simple configuration by shifting optical complexity into the digital signal processing regime. We use digitally enhanced homodyne interferometry in a simple, all-fiber Michelson interferometer to achieve a frequency reference stability of better than 20 Hz/√Hz from 10 mHz to 1 Hz, satisfying, for the first time in an all fiber system, the stability requirements for the Gravity Recovery and Climate Experiment Follow On mission. In addition, we have demonstrated stability that satisfies the future mission objectives at frequencies down to 1 mHz. This frequency domain stability translates into a fractional Allan deviation of 3.3 × 10(-17) for an integration time of 55 seconds. PMID:25089435

  4. Hydrogen Lines in Mira Stars Through Interferometry and Polarimetry

    NASA Astrophysics Data System (ADS)

    Fabas, N.; Chiavassa, A.; Millour, F.; Wittkowski, M.

    2015-12-01

    Balmer lines in emission are the most prominent features in Mira stars spectra and have a strong potential as a proxy to study the lower atmosphere's dynamics. In Fabas et al. ([1]), we accumulated spectropolarimetric observations of Balmer lines in emission. As the shock is propagating outwards, linear polarization rate increases and the angle of this polarization evolves. Assuming that linear polarization arises from anisotropic scattering, it has the potential of telling us about the geometric structure of the shock as it propagates and the study of such atmospheric structures can typically be performed with interferometry. In 2012, AMBER data on the Mira star omicron Ceti were collected in which the Brackett γ line is studied. The data show signatures in the interferometric observables around this line. Olivier Chesneau was in the jury evaluating the PhD thesis of N. Fabas and he was seduced by the idea to study these shock waves with interferometry and use polarimetry as a complementary study.

  5. Hanbury Brown and Twiss interferometry with interacting photons

    NASA Astrophysics Data System (ADS)

    Bromberg, Y.; Lahini, Y.; Small, E.; Silberberg, Y.

    2010-10-01

    Five decades ago, Hanbury Brown and Twiss (HBT) demonstrated that the angular size of stars can be measured by correlating the intensity fluctuations measured by two detectors at two different locations. Since then, non-local correlation measurements have become ubiquitous in many areas of physics and have also been applied, beyond photons, to electrons, matter waves and subatomic particles. An important assumption in HBT interferometry is that the particles do not interact on their way from the source to the detectors. However, this assumption is not always valid. Here, we study the effects of interactions on HBT interferometry by considering the propagation of light fields in a nonlinear medium that induces interactions between the photons. We show that interactions affect multipath interference, limiting the ability to extract information on the source. Nevertheless, we find that proper analysis of the intensity fluctuations can recover the size of the source, even in the presence of interactions.

  6. Experimental steps towards a digital revival of Stellar Intensity Interferometry

    NASA Astrophysics Data System (ADS)

    Matthews, Nolan; Kieda, David; Lebohec, Stephan; Abeysekara, Udara

    2016-03-01

    Over the last decade there has been a growing interest in using Stellar intensity interferometry (sii) for high-resolution imaging of hot stars in the optical and uv. In contrast to standard amplitude interferometry, the sii technique is unaffected by atmospheric turbulence allowing for extremely large baselines (>100m) and angular resolution scales down to tens of micro-arcseconds. The technique can be applied to existing and planned observatories which employ imaging air cherenkov telescopes (iacts) due to the similar requirements of large light collection areas and nano-second time resolution capabilities. The university of utah operates the starbase-utah observatory, located in Grantsville, ut, consisting of dual three meter diameter telescopes serving as a test-bed for sii instrumentation. I will summarize the sii technique and highlight the motivation for using sii. I will also present laboratory results in the reconstruction of artificial sources using pseudo-thermal light and the development of starbase-utah.

  7. Data compression for speckle correlation interferometry temporal fringe pattern analysis

    SciTech Connect

    Tuck Wah Ng; Kar Tien Ang

    2005-05-01

    Temporal fringe pattern analysis is gaining prominence in speckle correlation interferometry, in particular for transient phenomena studies. This form of analysis, nevertheless, necessitates large data storage. Current compression schemes do not facilitate efficient data retrieval and may even result in important data loss. We describe a novel compression scheme that does not result in crucial data loss and allows for the efficient retrieval of data for temporal fringe analysis. In sample tests with digital speckle interferometry on fringe patterns of a plate and of a cantilever beam subjected to temporal phase and load evolution, respectively, we achieved a compression ratio of 1.6 without filtering out any data from discontinuous and low fringe modulation spatial points. By eliminating 38% of the data from discontinuous and low fringe modulation spatial points, we attained a significant compression ratio of 2.4.

  8. Interferometry With ENVISAT ASAR Alternating Polarization Mode Data

    NASA Astrophysics Data System (ADS)

    Zhou, Xiao; Zeng, Qiming; Liang, Cunren; Cui, Xiai; Jiao, Jian

    2010-10-01

    The Environmental Satellite Advanced Synthetic Aperture Radar (ASAR) sensor has been designed to provide enhanced capabilities for interferometric applications [?]. Different types of interferometric products can be obtained by combining the various ASAR modes, most of which are stripmap [image mode (IM)] and ScanSAR [wide swath (WS) mode]. However, the Alternating Polarization [AP mode] has been rarely used for interferometric experiments. This letter deals with the possibility of using AP mode data to produce two kinds of differential interferograms (HH/HH and HH/VV). We propose a complete processing chain of AP mode interferometry and the results are encouraging, of which the specialty of meaning is explained. The data is processed by the newly developed Peking University Multi-mode SAR Interferometry Processing Kit (PUMSIP v1.0), supported by ROI_PAC of JPL/Caltech.

  9. Radio and Optical Interferometry: Basic Observing Techniques and Data Analysis

    NASA Astrophysics Data System (ADS)

    Monnier, John D.; Allen, Ronald J.

    Astronomers usually need the highest angular resolution possible when observing celestial objects, but the blurring effect of diffraction imposes a fundamental limit on the image quality from any single telescope. Interferometry allows light collected at widely separated telescopes to be combined in order to synthesize an aperture much larger than an individual telescope, thereby improving angular resolution by orders of magnitude. Because diffraction has the largest effect for long wavelengths, radio and millimeter wave astronomers dependon interferometry to achieve image quality on par with conventional large-aperture visible and infrared telescopes. Interferometers at visible and infrared wavelengths extend angular resolution below the milliarcsecond level to openup unique research areas in imaging stellar surfaces and circumstellar environments.

  10. Searching for Dark Matter with Atomic Clocks and Laser Interferometry

    NASA Astrophysics Data System (ADS)

    Stadnik, Yevgeny; Flambaum, Victor

    2016-05-01

    We propose new schemes for the direct detection of low-mass bosonic dark matter, which forms a coherently oscillating classical field and resides in the observed galactic dark matter haloes, using atomic clock, atomic spectroscopy and laser interferometry measurements in the laboratory. We have recently shown that such dark matter can produce both a `slow' cosmological evolution and oscillating variations in the fundamental constants. Using recent atomic dysprosium spectroscopy measurements in, we have derived limits on the quadratic interactions of scalar dark matter with ordinary matter that improve on existing constraints by up to 15 orders of magnitude. We have also proposed the use of laser and maser interferometry as novel high-precision platforms to search for dark matter, with effects due to the variation of the electromagnetic fine-structure constant on alterations in the accumulated phase enhanced by up to 14 orders of magnitude. Other possibilities include the use of highly-charged ions, molecules and nuclear clocks.

  11. Holodiagram: elliptic visualizing interferometry, relativity, and light-in-flight.

    PubMed

    Abramson, Nils H

    2014-04-10

    In holographic interferometry, there is usually a static distance separating the point of illumination and the point of observation. In Special Relativity, this separation is dynamic and is caused by the velocity of the observer. The corrections needed to compensate for these separations are similar in the two fields. We use the ellipsoids of the holodiagram for measurement and in a graphic way to explain and evaluate optical resolution, gated viewing, radar, holography, three-dimensional interferometry, Special Relativity, and light-in-flight recordings. Lorentz contraction together with time dilation is explained as the result of the eccentricity of the measuring ellipsoid, caused by its velocity. The extremely thin ellipsoid of the very first light appears as a beam aimed directly at the observer, which might explain the wave or ray duality of light and entanglement. Finally, we introduce the concept of ellipsoids of observation. PMID:24787410

  12. Observations of binary stars by speckle interferometry. II

    NASA Astrophysics Data System (ADS)

    Morgan, B. L.; Beckmann, G. K.; Scaddan, R. J.

    1980-07-01

    This is the second paper in a series describing observations of binary stars using the technique of speckle interferometry. Observations were made using the 2.5-m Newton Telescope and the 1-m telescope of the Royal Greenwich Observatory and the 1.9-m telescope of the South African Astronomical Observatory. The classical Rayleigh diffraction limits are 0.050 arcsec for the 2.5-m telescope, 0.065 arcsec for the 1.9-m telescope and 0.125 arcsec for the 1-m telescope, at a wavelength of 500 nm. The results of 29 measurements of 26 objects are presented. The objects include long period spectroscopic binaries from the 6th Catalog of Batten, close visual binary systems from the 3rd Catalog of Finsen and Worley and variable stars. Nine of the objects have not been previously resolved by speckle interferometry. New members are detected in the systems Beta Cep, p Vel and Iota UMa.

  13. The Balloon Experimental Twin Telescope for Infrared Interferometry

    NASA Astrophysics Data System (ADS)

    Rinehart, S. A.; BETTII Team

    2010-10-01

    Astronomical studies at infrared wavelengths have dramatically improved our understanding of the universe, and Herschel and SOFIA will continue to provide exciting new discoveries. However, the relatively low angular resolution of these missions limits our ability to answer key science questions. Interferometry enables high angular resolution at long wavelengths - a powerful tool for scientific discovery. We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII), and eight-meter baseline Michelson stellar interferometer to fly on a high-altitude balloon. BETTII, using a double-Fourier technique, will simultaneously obtain spatial and spectral information. Further, BETTII will serve as a technological pathfinder for future space-based interferometers such as FKSI, TPF-I, and Darwin.

  14. Noise Characterization of Supercontinuum Sources for Low Coherence Interferometry Applications

    PubMed Central

    Brown, William J.; Kim, Sanghoon; Wax, Adam

    2015-01-01

    We examine the noise properties of supercontinuum light sources when used in low coherence interferometry applications. The first application is a multiple-scattering low-coherence interferometry (ms2/LCI) system where high power and long image acquisition times are required to image deep into tissue. For this system we compare the noise characteristics of two supercontinuum sources from different suppliers. Both sources have long term drift that limits the amount of time over which signal averaging is advantageous for reducing noise. The second application is a high resolution optical coherence tomography system where broadband light is needed for high axial resolution. For this system we compare the noise performance of the two supercontinuum sources and a light source based on four superluminescent diodes (SLDs) using imaging contrast as a comparative metric. We find that the NKT SuperK has superior noise performance compared to the Fianium SC-450-4 but neither meets the performance of the SLDs. PMID:25606759

  15. Optical Distortion Evaluation in Large Area Windows using Interferometry

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C.; Skow, Miles; Nurge, Mark A.

    2015-01-01

    It is important that imagery seen through large area windows, such as those used on space vehicles, not be substantially distorted. Many approaches are described in the literature for measuring the distortion of an optical window, but most suffer from either poor resolution or processing difficulties. In this paper a new definition of distortion is presented, allowing accurate measurement using an optical interferometer. This new definition is shown to be equivalent to the definitions provided by the military and the standards organizations. In order to determine the advantages and disadvantages of this new approach the distortion of an acrylic window is measured using three different methods; image comparison, Moiré interferometry, and phase-shifting interferometry.

  16. Education in acoustics in Argentina

    NASA Astrophysics Data System (ADS)

    Miyara, Federico

    2002-11-01

    Over the last decades, education in acoustics (EA) in Argentina has experienced ups and downs due to economic and political issues interfering with long term projects. Unlike other countries, like Chile, where EA has reached maturity in spite of the acoustical industry having shown little development, Argentina has several well-established manufacturers of acoustic materials and equipment but no specific career with a major in acoustics. At the university level, acoustics is taught as a complementary--often elective--course for careers such as architecture, communication engineering, or music. In spite of this there are several research centers with programs covering environmental and community noise, effects of noise on man, acoustic signal processing, musical acoustics and acoustic emission, and several national and international meetings are held each year in which results are communicated and discussed. Several books on a variety of topics such as sound system, architectural acoustics, and noise control have been published as well. Another chapter in EA is technical and vocational education, ranging between secondary and postsecondary levels, with technical training on sound system operation or design. Over the last years there have been several attempts to implement master degrees in acoustics or audio engineering, with little or no success.

  17. Acoustic energy harvesting based on a planar acoustic metamaterial

    NASA Astrophysics Data System (ADS)

    Qi, Shuibao; Oudich, Mourad; Li, Yong; Assouar, Badreddine

    2016-06-01

    We theoretically report on an innovative and practical acoustic energy harvester based on a defected acoustic metamaterial (AMM) with piezoelectric material. The idea is to create suitable resonant defects in an AMM to confine the strain energy originating from an acoustic incidence. This scavenged energy is converted into electrical energy by attaching a structured piezoelectric material into the defect area of the AMM. We show an acoustic energy harvester based on a meta-structure capable of producing electrical power from an acoustic pressure. Numerical simulations are provided to analyze and elucidate the principles and the performances of the proposed system. A maximum output voltage of 1.3 V and a power density of 0.54 μW/cm3 are obtained at a frequency of 2257.5 Hz. The proposed concept should have broad applications on energy harvesting as well as on low-frequency sound isolation, since this system acts as both acoustic insulator and energy harvester.

  18. Acoustics Discipline Overview

    NASA Technical Reports Server (NTRS)

    Envia, Edmane; Thomas, Russell

    2007-01-01

    As part of the Fundamental Aeronautics Program Annual Review, a summary of the progress made in 2007 in acoustics research under the Subsonic Fixed Wing project is given. The presentation describes highlights from in-house and external activities including partnerships and NRA-funded research with industry and academia. Brief progress reports from all acoustics Phase 1 NRAs are also included as are outlines of the planned activities for 2008 and all Phase 2 NRAs. N+1 and N+2 technology paths outlined for Subsonic Fixed Wing noise targets. NRA Round 1 progressing with focus on prediction method advancement. NRA Round 2 initiating work focused on N+2 technology, prediction methods, and validation. Excellent partnerships in progress supporting N+1 technology targets and providing key data sets.

  19. Radiosurgery of acoustic neurinomas

    SciTech Connect

    Flickinger, J.C.; Lunsford, L.D.; Coffey, R.J.; Linskey, M.E.; Bissonette, D.J.; Maitz, A.H.; Kondziolka, D. )

    1991-01-15

    Eighty-five patients with acoustic neurinomas underwent stereotactic radiosurgery with the gamma unit at the University of Pittsburgh (Pittsburgh, PA) during its first 30 months of operation. Neuroimaging studies performed in 40 patients with more than 1 year follow-up showed that tumors were smaller in 22 (55%), unchanged in 17 (43%), and larger in one (2%). The 2-year actuarial rates for preservation of useful hearing and any hearing were 46% and 62%, respectively. Previously undetected neuropathies of the trigeminal (n = 12) and facial nerves (n = 14) occurred 1 week to 1 year after radiosurgery (median, 7 and 6 months, respectively), and improved at median intervals of 13 and 8 months, respectively, after onset. Hearing loss was significantly associated with increasing average tumor diameter (P = 0.04). No deterioration of any cranial nerve function has yet developed in seven patients with average tumor diameters less than 10 mm. Radiosurgery is an important treatment alternative for selected acoustic neurinoma patients.

  20. Acoustic methodology review

    NASA Technical Reports Server (NTRS)

    Schlegel, R. G.

    1982-01-01

    It is important for industry and NASA to assess the status of acoustic design technology for predicting and controlling helicopter external noise in order for a meaningful research program to be formulated which will address this problem. The prediction methodologies available to the designer and the acoustic engineer are three-fold. First is what has been described as a first principle analysis. This analysis approach attempts to remove any empiricism from the analysis process and deals with a theoretical mechanism approach to predicting the noise. The second approach attempts to combine first principle methodology (when available) with empirical data to formulate source predictors which can be combined to predict vehicle levels. The third is an empirical analysis, which attempts to generalize measured trends into a vehicle noise prediction method. This paper will briefly address each.

  1. Acoustic tractor beam.

    PubMed

    Démoré, Christine E M; Dahl, Patrick M; Yang, Zhengyi; Glynne-Jones, Peter; Melzer, Andreas; Cochran, Sandy; MacDonald, Michael P; Spalding, Gabriel C

    2014-05-01

    Negative radiation forces act opposite to the direction of propagation, or net momentum, of a beam but have previously been challenging to definitively demonstrate. We report an experimental acoustic tractor beam generated by an ultrasonic array operating on macroscopic targets (>1 cm) to demonstrate the negative radiation forces and to map out regimes over which they dominate, which we compare to simulations. The result and the geometrically simple configuration show that the effect is due to nonconservative forces, produced by redirection of a momentum flux from the angled sides of a target and not by conservative forces from a potential energy gradient. Use of a simple acoustic setup provides an easily understood illustration of the negative radiation pressure concept for tractor beams and demonstrates continuous attraction towards the source, against a net momentum flux in the system. PMID:24836252

  2. Acoustic Tractor Beam

    NASA Astrophysics Data System (ADS)

    Démoré, Christine E. M.; Dahl, Patrick M.; Yang, Zhengyi; Glynne-Jones, Peter; Melzer, Andreas; Cochran, Sandy; MacDonald, Michael P.; Spalding, Gabriel C.

    2014-05-01

    Negative radiation forces act opposite to the direction of propagation, or net momentum, of a beam but have previously been challenging to definitively demonstrate. We report an experimental acoustic tractor beam generated by an ultrasonic array operating on macroscopic targets (>1 cm) to demonstrate the negative radiation forces and to map out regimes over which they dominate, which we compare to simulations. The result and the geometrically simple configuration show that the effect is due to nonconservative forces, produced by redirection of a momentum flux from the angled sides of a target and not by conservative forces from a potential energy gradient. Use of a simple acoustic setup provides an easily understood illustration of the negative radiation pressure concept for tractor beams and demonstrates continuous attraction towards the source, against a net momentum flux in the system.

  3. Alaskan river environmental acoustics

    NASA Astrophysics Data System (ADS)

    Dahl, Peter H.; Pfisterer, Carl; Geiger, Harold J.

    2005-04-01

    Sonars are used by the Alaska Department of Fish and Game (ADF&G) to obtain daily and hourly estimates of at least four species of migratory salmon during their seasonal migration which lasts from June to beginning of September. Suspended sediments associated with a river's sediment load is an important issue for ADF&G's sonar operations. Acoustically, the suspended sediments are a source of both volume reverberation and excess attenuation beyond that expected in fresh water. Each can impact daily protocols for fish enumeration via sonar. In this talk, results from an environmental acoustic study conducted in the Kenai River (June 1999) using 420 kHz and 200 kHz side looking sonars, and in the Yukon River (July 2001) using a 120 kHz side looking sonar, are discussed. Estimates of the volume scattering coefficient and attenuation are related to total suspended sediments. The relative impact of bubble scattering and sediment scattering is also discussed.

  4. Structural Acoustics and Vibrations

    NASA Astrophysics Data System (ADS)

    Chaigne, Antoine

    This structural chapter is devoted to vibrations of structures and to their coupling with the acoustic field. Depending on the context, the radiated sound can be judged as desirable, as is mostly the case for musical instruments, or undesirable, like noise generated by machinery. In architectural acoustics, one main goal is to limit the transmission of sound through walls. In the automobile industry, the engineers have to control the noise generated inside and outside the passenger compartment. This can be achieved by means of passive or active damping. In general, there is a strong need for quieter products and better sound quality generated by the structures in our daily environment.

  5. A Martian acoustic anemometer.

    PubMed

    Banfield, Don; Schindel, David W; Tarr, Steve; Dissly, Richard W

    2016-08-01

    An acoustic anemometer for use on Mars has been developed. To understand the processes that control the interaction between surface and atmosphere on Mars, not only the mean winds, but also the turbulent boundary layer, the fluxes of momentum, heat and molecular constituents between surface and atmosphere must be measured. Terrestrially this is done with acoustic anemometers, but the low density atmosphere on Mars makes it challenging to adapt such an instrument for use on Mars. This has been achieved using capacitive transducers and pulse compression, and was successfully demonstrated on a stratospheric balloon (simulating the Martian environment) and in a dedicated Mars Wind Tunnel facility. This instrument achieves a measurement accuracy of ∼5 cm/s with an update rate of >20 Hz under Martian conditions. PMID:27586767

  6. Books on acoustics

    NASA Astrophysics Data System (ADS)

    Shaw, Neil A.

    2001-05-01

    The legacy of a man is not limited to just his projects. His writings in many cases are a more lasting, and a definitely more accessible, monument. For 60 years, Leo L. Beranek has produced books on acoustics, acoustic measurements, sound control, music and architecture, noise and vibration control, concert halls, and opera houses in addition to teaching and consulting. His books are standard references and still cited in other books and in technical and professional articles. Many of his books were among, if not, the first comprehensive modern treatment of the subject and many are still foremost. A review of Dr. Beranek's many books as well as some anecdotes about the circumstances and consequences of same will be presented.

  7. HBT interferometry and the parton-hadron phase transition

    SciTech Connect

    Soff, Sven

    2002-02-23

    The authors discuss predictions for the pion and kaon interferometry measurements in relativistic heavy ion collisions at SPS and RHIC energies. In particular, they confront relativistic transport model calculations that include explicitly a first-order phase transition from a thermalized quark-gluon plasma to a hadron gas with recent data from the RHIC experiments. They critically examine the HBT-puzzle both from the theoretical as well as from the experimental point of view. Alternative scenarios are briefly explained.

  8. Laser Development for Gravitational-Wave Interferometry in Space

    NASA Astrophysics Data System (ADS)

    Numata, K.

    2013-01-01

    We are reporting on our development work on laser (master oscillator) and optical amplifier systems for gravitational-wave interferometry in space. Our system is based on the mature, wave-guided optics technologies, which have advantages over bulk, crystal-based, free-space optics. We are investing in a new type of compact, low-noise master oscillator, called the planar-waveguide external cavity diode laser. We made measurements, including those of noise, and performed space-qualification tests.

  9. Spatial interferometry for white light processing: The coherence interferometer

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.

    1984-01-01

    An optical systems design approach for a parallel optical processor that has an information throughput capacity in excess of one petabit per second is discussed. This system enables predetection processing of white light, passively illuminated scenes. Integrated with a programmable Van der Lugt filter, this system is an effective data compression method. A program to implement this parallel optical processing by interferometry system is discussed.

  10. Laser Development for Gravitational-Wave Interferometry in Space

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Camp, Jordan

    2012-01-01

    We are reporting on our development work on laser (master oscillator) and optical amplifier systems for gravitational-wave interferometry in space. Our system is based on the mature, wave-guided optics technologies, which have advantages over bulk, crystal-based, free-space optics. We are investing in a new type of compact, low-noise master oscillator, called the planar-waveguide external cavity diode laser. We made measurements, including those of noise, and performed space-qualification tests.

  11. Using Atom Interferometry to Search for New Forces

    SciTech Connect

    Wacker, Jay G.; /SLAC

    2009-12-11

    Atom interferometry is a rapidly advancing field and this Letter proposes an experiment based on existing technology that can search for new short distance forces. With current technology it is possible to improve the sensitivity by up to a factor of 10{sup 2} and near-future advances will be able to rewrite the limits for forces with ranges from 100 {micro}m to 1km.

  12. Infrasonic interferometry applied to synthetic and measured data

    NASA Astrophysics Data System (ADS)

    Fricke, Julius T.; Evers, Läslo G.; Ruigrok, Elmer; Wapenaar, Kees; Simons, Dick G.

    2013-04-01

    The estimation of the traveltime of infrasound through the atmosphere is interesting for several applications. For example, it could be used to determine temperature and wind of the atmosphere, since the traveltime depends on these atmospheric conditions (Haney, 2009). In this work the traveltime is estimated with infrasonic interferometry. In other words, we calculate the crosscorrelations of data of spatially distributed receivers. With this method the traveltime between two receivers is determined without the need for ground truth events. In a first step, we crosscorrelate synthetic data, which are generated by a raytracing model. This model takes into account the traveltime along the rays, the attenuation of the different atmospheric layers, the spreading of the rays and the influence of caustics. In these numerical experiments we show that it is possible to determine the traveltime through infrasonic interferometry. We present the results of infrasonic interferometry applied to measured data. Microbaroms are used in the crosscorrelation approach. Microbaroms are caused by ocean waves and are measured by the 'Large Aperture Infrasound Array' (LAIA). LAIA is being installed by the Royal Netherlands Meteorological Institute (KNMI) in the framework of the radio-astronomical 'Low Frequency Array' (LOFAR) initiative. LAIA consists currently of around twenty receivers (microbarometers) with an aperture of around 100 km, allowing for several inter-station distances. Here, we show the results of crosscorrelations as a function of receivers distance, to assess the signal coherency. This research is made possible by the support of the 'Netherlands Organization for Scientific Research' (NWO). Haney, M., 2009. Infrasonic ambient noise interferometry from correlations of microbaroms, Geophysical Research Letters, 36, L19808

  13. Sagnac interferometry using bright matter-wave solitons.

    PubMed

    Helm, J L; Cornish, S L; Gardiner, S A

    2015-04-01

    We use an effective one-dimensional Gross-Pitaevskii equation to study bright matter-wave solitons held in a tightly confining toroidal trapping potential, in a rotating frame of reference, as they are split and recombined on narrow barrier potentials. In particular, we present an analytical and numerical analysis of the phase evolution of the solitons and delimit a velocity regime in which soliton Sagnac interferometry is possible, taking account of the effect of quantum uncertainty. PMID:25884125

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

    NASA Technical Reports Server (NTRS)

    Hanel, R. A.

    1985-01-01

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

  15. Real-time laser holographic Interferometry for aerodynamics

    NASA Technical Reports Server (NTRS)

    Lee, George

    1987-01-01

    Recent developments in thermoplastic recording holograms and advancements in automated image digitalization and analysis make real-time laser holographic interferometry feasible for two-dimensional flows such as airfoil flows. Typical airfoil measurements would include airfoil presssure distributions, wake and boundary layer profiles, and flow field density contours. This paper addresses some of the problems and requirements of a real-time laser holographic interferometer.

  16. Real-time laser holographic interferometry for aerodynamics

    NASA Technical Reports Server (NTRS)

    Lee, George

    1987-01-01

    Recent developments in thermoplastic recording holograms and advancements in automated image digitalization and analysis make real-time laser holographic interferometry feasible for two-dimensional flows such as airfoil flows. Typical airfoil measurements would include airfoil pressure distributions, wake and boundary layer profiles, and flow field density contours. This paper addresses some of the problems and requirements of a real-time laser holographic interferometer.

  17. Gouy Interferometry: Properties of Multicomponent System Omega Graphs

    SciTech Connect

    Miller, D G

    2007-01-24

    We consider the properties of {Omega} graphs ({Omega} vs f(z)) obtained from Gouy interferometry on multicomponent systems with constant diffusion coefficients. We show that they must have (a) either a maximum or else a minimum between f(z)=0 and f(z)=1 and (b) an inflection point between the f(z) value at the extremum and f(z)=1. Consequently, an {Omega} graph cannot have both positive and negative {Omega} values.

  18. Circumstellar Matter Studied by Spectrally-Resolved Interferometry

    NASA Astrophysics Data System (ADS)

    Millour, F.

    2012-12-01

    This paper describes some generalities about spectro-interferometry and the role it has played in the last decade for the better understanding of circumstellar matter. I provide a small history of the technique and its origins, and recall the basics of differential phase and its central role for the recent discoveries. I finally provide a small set of simple interpretations of differential phases for specific astrophysical cases, and intend to provide a "cookbook" for the other cases.

  19. Theory on acoustic sources

    NASA Technical Reports Server (NTRS)

    Wright, S. E.

    1978-01-01

    A theory is described for the radiation emission emission from acoustic multipole sources. The sources can be stationary or moving at speeds including supersonic and experience stationary or moving disturbances. The effect of finite source distributions and disturbances is investigated as well as the manner in which they interact. Distinction is made between source distributions that responsed as a function of time and those that respond as a function of space.

  20. Acoustic velocity meter systems

    USGS Publications Warehouse

    Laenen, Antonius

    1985-01-01

    Acoustic velocity meter (AVM) systems operate on the principles that the point-to-point upstream traveltime of an acoustic pulse is longer than the downstream traveltime and that this difference in traveltime can be accurately measured by electronic devices. An AVM system is capable of recording water velocity (and discharge) under a wide range of conditions, but some constraints apply: 1. Accuracy is reduced and performance is degraded if the acoustic path is not a continuous straight line. The path can be bent by reflection if it is too close to a stream boundary or by refraction if it passes through density gradients resulting from variations in either water temperature or salinity. For paths of less than 100 m, a temperature gradient of 0.1' per meter causes signal bending less than 0.6 meter at midchannel, and satisfactory velocity results can be obtained. Reflection from stream boundaries can cause signal cancellation if boundaries are too close to signal path. 2. Signal strength is attenuated by particles or bubbles that absorb, spread, or scatter sound. The concentration of particles or bubbles that can be tolerated is a function of the path length and frequency of the acoustic signal. 3. Changes in streamline orientation can affect system accuracy if the variability is random. 4. Errors relating to signal resolution are much larger for a single threshold detection scheme than for multiple threshold schemes. This report provides methods for computing the effect of various conditions on the accuracy of a record obtained from an AVM. The equipment must be adapted to the site. Field reconnaissance and preinstallation analysis to detect possible problems are critical for proper installation and operation of an AVM system.

  1. Structures and Acoustics Division

    NASA Technical Reports Server (NTRS)

    Acquaviva, Cynthia S.

    1999-01-01

    The Structures and Acoustics Division of NASA Glenn Research Center is an international leader in rotating structures, mechanical components, fatigue and fracture, and structural aeroacoustics. Included are disciplines related to life prediction and reliability, nondestructive evaluation, and mechanical drive systems. Reported are a synopsis of the work and accomplishments reported by the Division during the 1996 calendar year. A bibliography containing 42 citations is provided.

  2. Structures and Acoustics Division

    NASA Technical Reports Server (NTRS)

    Acquaviva, Cynthia S.

    2001-01-01

    The Structures and Acoustics Division of the NASA Glenn Research Center is an international leader in rotating structures, mechanical components, fatigue and fracture, and structural aeroacoustics. Included in this report are disciplines related to life prediction and reliability, nondestructive evaluation, and mechanical drive systems. Reported is a synopsis of the work and accomplishments completed by the Division during the 1997, 1998, and 1999 calendar years. A bibliography containing 93 citations is provided.

  3. Fast wideband acoustical holography.

    PubMed

    Hald, Jørgen

    2016-04-01

    Patch near-field acoustical holography methods like statistically optimized near-field acoustical holography and equivalent source method are limited to relatively low frequencies, where the average array-element spacing is less than half of the acoustic wavelength, while beamforming provides useful resolution only at medium-to-high frequencies. With adequate array design, both methods can be used with the same array. But for holography to provide good low-frequency resolution, a small measurement distance is needed, whereas beamforming requires a larger distance to limit sidelobe issues. The wideband holography method of the present paper was developed to overcome that practical conflict. Only a single measurement is needed at a relatively short distance and a single result is obtained covering the full frequency range. The method uses the principles of compressed sensing: A sparse sound field representation is assumed with a chosen set of basis functions, a measurement is taken with an irregular array, and the inverse problem is solved with a method that enforces sparsity in the coefficient vector. Instead of using regularization based on the 1-norm of the coefficient vector, an iterative solution procedure is used that promotes sparsity. The iterative method is shown to provide very similar results in most cases and to be computationally much more efficient. PMID:27106299

  4. Acoustic paramagnetic logging tool

    DOEpatents

    Vail, III, William B.

    1988-01-01

    New methods and apparatus are disclosed which allow measurement of the presence of oil and water in geological formations using a new physical effect called the Acoustic Paramagnetic Logging Effect (APLE). The presence of petroleum in formation causes a slight increase in the earth's magnetic field in the vicinity of the reservoir. This is the phenomena of paramagnetism. Application of an acoustic source to a geological formation at the Larmor frequency of the nucleons present causes the paramagnetism of the formation to disappear. This results in a decrease in the earth3 s magnetic field in the vicinity of the oil bearing formation. Repetitively frequency sweeping the acoustic source through the Larmor frequency of the nucleons present (approx. 2 kHz) causes an amplitude modulation of the earth's magnetic field which is a consequence of the APLE. The amplitude modulation of the earth's magnetic field is measured with an induction coil gradiometer and provides a direct measure of the amount of oil and water in the excitation zone of the formation . The phase of the signal is used to infer the longitudinal relaxation times of the fluids present, which results in the ability in general to separate oil and water and to measure the viscosity of the oil present. Such measurements may be preformed in open boreholes and in cased well bores.

  5. Scanning tomographic acoustic microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Hua

    2002-11-01

    This paper provides an overview of the design and development of the scanning tomographic acoustic microscopy (STAM). This research effort spans over a period of more than 12 years, which successfully elevated the acoustic microscopy from the traditional intensity-mapping mode to the level of holographic and tomographic imaging. The tomographic imaging capability of STAM was developed on the platform of the scanning laser acoustic microscope (SLAM), which operates in a coherent transmission mode with plane-wave illumination and scanning laser wavefield detection. The image formation techniques were based on the backward propagation method implemented in the plane-to-plane format. In this paper, the key elements of the design and development, including the modification of the data-acquisition hardware, implementation of image reconstruction algorithms for multiple-frequency and multiple-angle tomography, and the high-precision phase-correction and image registration techniques for the superposition of coherent sub-images, will be discussed. Results of full-scale experiments will also be included to demonstrate the capability of holographic and tomographic image formation in microscopic scale.

  6. Acoustically enhanced heat transport.

    PubMed

    Ang, Kar M; Yeo, Leslie Y; Friend, James R; Hung, Yew Mun; Tan, Ming K

    2016-01-01

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ∼ 10(6) Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξs ∼ 10(-9) m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξs ∼ 10(-8) m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10(-8) m with 10(6) Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation. PMID:26827343

  7. Acoustically enhanced heat transport

    NASA Astrophysics Data System (ADS)

    Ang, Kar M.; Yeo, Leslie Y.; Friend, James R.; Hung, Yew Mun; Tan, Ming K.

    2016-01-01

    We investigate the enhancement of heat transfer in the nucleate boiling regime by inducing high frequency acoustic waves (f ˜ 106 Hz) on the heated surface. In the experiments, liquid droplets (deionized water) are dispensed directly onto a heated, vibrating substrate. At lower vibration amplitudes (ξs ˜ 10-9 m), the improved heat transfer is mainly due to the detachment of vapor bubbles from the heated surface and the induced thermal mixing. Upon increasing the vibration amplitude (ξs ˜ 10-8 m), the heat transfer becomes more substantial due to the rapid bursting of vapor bubbles happening at the liquid-air interface as a consequence of capillary waves travelling in the thin liquid film between the vapor bubble and the air. Further increases then lead to rapid atomization that continues to enhance the heat transfer. An acoustic wave displacement amplitude on the order of 10-8 m with 106 Hz order frequencies is observed to produce an improvement of up to 50% reduction in the surface temperature over the case without acoustic excitation.

  8. Spatiotemporally resolved granular acoustics

    NASA Astrophysics Data System (ADS)

    Owens, Eli; Daniels, Karen

    2011-03-01

    Acoustic techniques provide a non-invasive method of characterizing granular material properties; however, there are many challenges in formulating accurate models of sound propagation due to the inherently heterogeneous nature of granular materials. In order to quantify acoustic responses in space and time, we perform experiments in a photoelastic granular material in which the internal stress pattern (in the form of force chains) is visible. We utilize two complementary methods, high-speed imaging and piezoelectric transduction, to provide particle-scale measurements of the amplitude of the acoustic wave. We observe that the average wave amplitude is largest within particles experiencing the largest forces. The force-dependence of this amplitude is in qualitative agreement with a simple Hertzian-like model for contact area. In addition, we investigate the power spectrum of the propagating signal using the piezoelectric sensors. For a Gaussian wave packet input, we observe a broad spectrum of transmitted frequencies below the driving frequency, and we quantify the characteristic frequencies and corresponding length scales of our material as the system pressure is varied.

  9. Infrared Vibrational Nanospectroscopy by Self-Referenced Interferometry.

    PubMed

    Pollard, Benjamin; Maia, Francisco C B; Raschke, Markus B; Freitas, Raul O

    2016-01-13

    Infrared vibrational scattering scanning near-field optical microscopy (s-SNOM) has emerged as a new frontier in imaging science due to its potential to provide nanoscale spatially resolved chemical spectroscopy for the investigation of molecular, soft-matter, and biological materials. As a phase-sensitive technique able to yield the full complex dielectric function of materials, different interferometric schemes have been developed involving asymmetric interferometry between sample and reference arms. In this work, we take advantage of a greatly simplified symmetric geometry that uses the spatially coherent background scattered light from within the confocal sample volume as a reference field for signal amplification in both self-homodyne and self-heterodyne interferometry. On the basis of a simple model for tip-sample scattering and interferometric detection, we demonstrate the measurement of the vibrational response of molecular materials in good agreement with established values. In addition to a compact design, enhanced signal levels, and a reduced sensitivity to fluctuations and drift, including those from the light source, self-referenced interferometry brings benefits for routine s-SNOM chemical spectroscopy, remaining robust even under a wide range of challenging experimental environments. PMID:26654680

  10. Stitching interferometry and absolute surface shape metrology: similarities

    NASA Astrophysics Data System (ADS)

    Bray, Michael

    2001-12-01

    Stitching interferometry is a method of analysing large optical components using a standard small interferometer. This result is obtained by taking multiple overlapping images of the large component, and numerically stitching these sub-apertures together by computing a correcting Tip- Tilt-Piston correction for each sub-aperture. All real-life measurement techniques require a calibration phase. By definition, a perfect surface does not exist. Methods abound for the accurate measurement of diameters (viz., the Three Flat Test). However, we need total surface knowledge of the reference surface, because the stitched overlap areas will suffer from the slightest deformation. One must not be induced into thinking that Stitching is the cause of this error: it simply highlights the lack of absolute knowledge of the reference surface, or the lack of adequate thermal control, issues which are often sidetracked... The goal of this paper is to highlight the above-mentioned calibration problems in interferometry in general, and in stitching interferometry in particular, and show how stitching hardware and software can be conveniently used to provide the required absolute surface shape metrology. Some measurement figures will illustrate this article.

  11. Terahertz reflection interferometry for automobile paint layer thickness measurement

    NASA Astrophysics Data System (ADS)

    Rahman, Aunik; Tator, Kenneth; Rahman, Anis

    2015-05-01

    Non-destructive terahertz reflection interferometry offers many advantages for sub-surface inspection such as interrogation of hidden defects and measurement of layers' thicknesses. Here, we describe a terahertz reflection interferometry (TRI) technique for non-contact measurement of paint panels where the paint is comprised of different layers of primer, basecoat, topcoat and clearcoat. Terahertz interferograms were generated by reflection from different layers of paints on a metallic substrate. These interferograms' peak spacing arising from the delay-time response of respective layers, allow one to model the thicknesses of the constituent layers. Interferograms generated at different incident angles show that the interferograms are more pronounced at certain angles than others. This "optimum" angle is also a function of different paint and substrate combinations. An automated angular scanning algorithm helps visualizing the evolution of the interferograms as a function of incident angle and also enables the identification of optimum reflection angle for a given paint-substrate combination. Additionally, scanning at different points on a substrate reveals that there are observable variations from one point to another of the same sample over its entire surface area. This ability may be used as a quality control tool for in-situ inspection in a production line. Keywords: Terahertz reflective interferometry, Paint and coating layers, Non-destructive

  12. Probing dusty circumstellar environments with polarimetric aperture-masking interferometry

    NASA Astrophysics Data System (ADS)

    Norris, Barnaby R. M.; Tuthill, Peter G.; Ireland, Michael J.; Lacour, Sylvestre; Zijlstra, Albert A.; Lykou, Foteini; Evans, Thomas M.; Stewart, Paul; Bedding, Timothy R.; Guyon, Olivier; Martinache, Frantz

    2012-07-01

    Aperture-masking interferometry allows diffraction-limited images to be recovered despite the turbulent atmo­ sphere. Here, this approach has been combined with polarimetry to form a novel technique allowing the dusty environments of mass-losing stars (so-called AGB stars) and proto-planetary and debris disks to be imaged, the characterisation of which is key to understanding the recycling of matter and the formation of new planetary systems. Polarimetric aperture-masking interferometry produces images by exploiting the fact that starlight scattered by circumstellar dust becomes strongly polarised. Essentially, aperture-masking allows access to the small spatial scales (rv1Omas) necessary while polarimetry allows light from the dust and star to be differentiated. Furthermore, measurements at multiple wavelengths allow dust grain sizes to be calculated using Mie scattering theory. Excellent results have already been obtained at near-IR wavelengths using the NACO instrument at the VLT. The next step is to leverage the higher spatial resolution and polarisation signal found in the visible, rather than near-IR. To this end, a new instrument allowing precision polarimetric aperture masking interferometry at 600-800nm is being developed for an 8m class telescope, details of which will also be presented.

  13. Surface displacement studies using differential SAR interferometry: an overview

    NASA Astrophysics Data System (ADS)

    Gupta, Sonal; Sajith V., K.; Arora, Manoj K.; Sharma, Mukut L.

    2006-12-01

    The differential SAR interferometry (DInSAR) has been increasing used to monitor ground surface displacements, which may be caused by various natural disasters such as earthquakes, landslides, mining activities, avalanches etc. Conventionally, these displacements were being estimated through field measurements, which are time consuming, hazardous and with data collected over few point locations. Since all the development and rehabilitation works after a natural disaster strikes is carried out on regional basis, any information at spatial level is advantageous in planning, management and monitoring activities. In recent years, the application of Differential SAR interferometry is gaining momentum to estimate the surface displacements at millimeter level accuracy. The displacement maps produced via this technique provide information at spatial level in the region thereby assisting in judicious developmental and planning works in an efficient and cost-effective manner. The aim of this paper is provide an overview of the use of Differential SAR Interferometry (DinSAR) technology for the study of surface displacements. As a case study, land subsidence occurred due to coal mining in Jharia coal fields, Jharkhand, have been estimated through this technique. All the procedural steps in implementing the approach based on DinSAR have been explained in a simplified manner.

  14. Comparison of Laser Interferometry and Atom Interferometry for Gravitational Wave Observations in Space

    NASA Astrophysics Data System (ADS)

    Bender, Peter L.

    2015-08-01

    1. In 2013 a suggestion was made by Graham et al. [1] [Phys. Rev. Lett. 110, 171102 (2013)] of possible GW observations over 10^3 km baselines using strongly forbidden single photon transitions in atoms such as Sr-87. A comparison of the requirements for such a mission with those for laser interferometer missions such as LISA or eLISA with roughly 10^6 km baselines was published in 2014 [Bender, Phys. Rev. D 89, 062004 (2014)]. The comparison will be somewhat updated in this talk.2. Recently, a possible method for gravitational wave observations with atom interferometry over million km scale baselines has been suggested by Hogan and Kasevich [arXiv:1501.06797v1 (2015)]. As an example, they consider observations similar to those discussed in [1], but over a 2*10^6 km baseline. The atomic transitions in the two spacecraft would be driven by separate lasers that are phase locked using 1 W laser power and 30 cm diam. telescopes. Total observation times for individual clouds of 80 to 320 s are assumed, along with 50 concurrent interferometers and a 60 Hz Rabi frequency for the laser pulses.3. After the flight of the LISA Pathfinder mission later this year, it is expected that more intensive work will start on a laser interferometer gravitational wave mission. Probably the most important objective will be the observation of GW signals from the mergers at high redshifts of massive black holes with masses in the range from perhaps 10^4 to 10^7 M_sun. Such signals would give new constraints on the mechanisms for the formation of intermediate mass and larger black holes at early times, and probably contribute to understanding the observed close correlation between the growth of galaxies and of the massive black holes at their centers.

  15. The use of holographic interferometry and electron speckle pattern interferometry for diffusion measurement in biochemical and pharmaceutical engineering applications

    NASA Astrophysics Data System (ADS)

    Axelsson, Anders; Marucci, Mariagrazia

    2008-12-01

    In this review holographic interferometry and electron speckle pattern interferometry are discussed as efficient techniques for diffusion measurements in biochemical and pharmaceutical applications. Transport phenomena can be studied, quantitatively and qualitatively, in gels, liquids and membranes. Detailed information on these phenomena is required to design effective chromatography bioseparation processes using gel beads or ultrafiltration membranes, and in the design of controlled-release pharmaceuticals using membrane-coated pellets or tablets. The influence of gel concentration, ion strength in the liquid and the size of diffusing protein molecules can easily be studied with good accuracy. When studying membranes, the resistance can be quantified, and it is also possible to discriminate between permeable and semi-permeable membranes. In this review the influence of temperature, natural convection and light deflection on the accuracy of the diffusion measurements is also discussed.

  16. Acoustic properties of triggered lightning

    NASA Astrophysics Data System (ADS)

    Dayeh, M. A.; Evans, N.; Ramaekers, J.; Trevino, J.; Rassoul, H.; Lucia, R. J.; Dwyer, J. R.; Uman, M. A.; Jordan, D. M.

    2014-12-01

    Acoustic signatures from rocket-triggered lightning are measured by a 15m long, one-dimensional microphone array consisting of 16 receivers situated 90 meters from the lightning channel. Measurements were taken at the International Center for Lightning Research and Testing (ICLRT) in Camp Blanding, FL during the summer of 2014. The linear array was oriented in an end-fire position so that the peak acoustic reception pattern can be steered vertically along the channel with a frequency-dependent spatial resolution, enabling us to sample the acoustic signatures from different portions along the lightning channel. We report on the characteristics of acoustic signatures associated with several return strokes in 6 measured flashes (total of 29 return strokes). In addition, we study the relationship between the amplitude, peak frequency, and inferred energy input of each stroke acoustic signature and the associated measured lightning parameters. Furthermore, challenges of obtaining acoustic measurements in thunderstorm harsh conditions and their countermeasures will also be discussed.

  17. Wireless Acoustic Measurement System

    NASA Technical Reports Server (NTRS)

    Anderson, Paul D.; Dorland, Wade D.; Jolly, Ronald L.

    2007-01-01

    A prototype wireless acoustic measurement system (WAMS) is one of two main subsystems of the Acoustic Prediction/ Measurement Tool, which comprises software, acoustic instrumentation, and electronic hardware combined to afford integrated capabilities for predicting and measuring noise emitted by rocket and jet engines. The other main subsystem is described in the article on page 8. The WAMS includes analog acoustic measurement instrumentation and analog and digital electronic circuitry combined with computer wireless local-area networking to enable (1) measurement of sound-pressure levels at multiple locations in the sound field of an engine under test and (2) recording and processing of the measurement data. At each field location, the measurements are taken by a portable unit, denoted a field station. There are ten field stations, each of which can take two channels of measurements. Each field station is equipped with two instrumentation microphones, a micro- ATX computer, a wireless network adapter, an environmental enclosure, a directional radio antenna, and a battery power supply. The environmental enclosure shields the computer from weather and from extreme acoustically induced vibrations. The power supply is based on a marine-service lead-acid storage battery that has enough capacity to support operation for as long as 10 hours. A desktop computer serves as a control server for the WAMS. The server is connected to a wireless router for communication with the field stations via a wireless local-area network that complies with wireless-network standard 802.11b of the Institute of Electrical and Electronics Engineers. The router and the wireless network adapters are controlled by use of Linux-compatible driver software. The server runs custom Linux software for synchronizing the recording of measurement data in the field stations. The software includes a module that provides an intuitive graphical user interface through which an operator at the control server

  18. Wireless Acoustic Measurement System

    NASA Technical Reports Server (NTRS)

    Anderson, Paul D.; Dorland, Wade D.

    2005-01-01

    A prototype wireless acoustic measurement system (WAMS) is one of two main subsystems of the Acoustic Prediction/Measurement Tool, which comprises software, acoustic instrumentation, and electronic hardware combined to afford integrated capabilities for predicting and measuring noise emitted by rocket and jet engines. The other main subsystem is described in "Predicting Rocket or Jet Noise in Real Time" (SSC-00215-1), which appears elsewhere in this issue of NASA Tech Briefs. The WAMS includes analog acoustic measurement instrumentation and analog and digital electronic circuitry combined with computer wireless local-area networking to enable (1) measurement of sound-pressure levels at multiple locations in the sound field of an engine under test and (2) recording and processing of the measurement data. At each field location, the measurements are taken by a portable unit, denoted a field station. There are ten field stations, each of which can take two channels of measurements. Each field station is equipped with two instrumentation microphones, a micro-ATX computer, a wireless network adapter, an environmental enclosure, a directional radio antenna, and a battery power supply. The environmental enclosure shields the computer from weather and from extreme acoustically induced vibrations. The power supply is based on a marine-service lead-acid storage battery that has enough capacity to support operation for as long as 10 hours. A desktop computer serves as a control server for the WAMS. The server is connected to a wireless router for communication with the field stations via a wireless local-area network that complies with wireless-network standard 802.11b of the Institute of Electrical and Electronics Engineers. The router and the wireless network adapters are controlled by use of Linux-compatible driver software. The server runs custom Linux software for synchronizing the recording of measurement data in the field stations. The software includes a module that

  19. Acoustic nonlinearity in dispersive solids

    NASA Technical Reports Server (NTRS)

    Cantrell, John H.; Yost, William T.

    1991-01-01

    An investigation to consider the effects of dispersion on the generation of the static acoustic wave component is presented. It is considered that an acoustic toneburst may be modeled as a modulated continuous waveform and that the generated initial static displacement pulse may be viewed as a modulation-confined disturbance. A theoretical model for the generation of the acoustic modulation solitons evolved is developed and experimental evidence in samples of vitreous silica demonstrating the essential validity of the model is provided.

  20. Spacecraft Internal Acoustic Environment Modeling

    NASA Technical Reports Server (NTRS)

    Chu, S. Reynold; Allen, Chris

    2009-01-01

    The objective of the project is to develop an acoustic modeling capability, based on commercial off-the-shelf software, to be used as a tool for oversight of the future manned Constellation vehicles. The use of such a model will help ensure compliance with acoustic requirements. Also, this project includes modeling validation and development feedback via building physical mockups and conducting acoustic measurements to compare with the predictions.

  1. Truck acoustic data analyzer system

    DOEpatents

    Haynes, Howard D.; Akerman, Alfred; Ayers, Curtis W.

    2006-07-04

    A passive vehicle acoustic data analyzer system having at least one microphone disposed in the acoustic field of a moving vehicle and a computer in electronic communication the microphone(s). The computer detects and measures the frequency shift in the acoustic signature emitted by the vehicle as it approaches and passes the microphone(s). The acoustic signature of a truck driving by a microphone can provide enough information to estimate the truck speed in miles-per-hour (mph), engine speed in rotations-per-minute (RPM), turbocharger speed in RPM, and vehicle weight.

  2. Transition section for acoustic waveguides

    DOEpatents

    Karplus, H.H.B.

    1975-10-28

    A means of facilitating the transmission of acoustic waves with minimal reflection between two regions having different specific acoustic impedances is described comprising a region exhibiting a constant product of cross-sectional area and specific acoustic impedance at each cross-sectional plane along the axis of the transition region. A variety of structures that exhibit this feature is disclosed, the preferred embodiment comprising a nested structure of doubly reentrant cones. This structure is useful for monitoring the operation of nuclear reactors in which random acoustic signals are generated in the course of operation.

  3. Guided acoustic wave inspection system

    DOEpatents

    Chinn, Diane J.

    2004-10-05

    A system for inspecting a conduit for undesirable characteristics. A transducer system induces guided acoustic waves onto said conduit. The transducer system detects the undesirable characteristics of the conduit by receiving guided acoustic waves that contain information about the undesirable characteristics. The conduit has at least two sides and the transducer system utilizes flexural modes of propagation to provide inspection using access from only the one side of the conduit. Cracking is detected with pulse-echo testing using one transducer to both send and receive the guided acoustic waves. Thinning is detected in through-transmission testing where one transducer sends and another transducer receives the guided acoustic waves.

  4. Powered-Lift Aerodynamics and Acoustics. [conferences

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Powered lift technology is reviewed. Topics covered include: (1) high lift aerodynamics; (2) high speed and cruise aerodynamics; (3) acoustics; (4) propulsion aerodynamics and acoustics; (5) aerodynamic and acoustic loads; and (6) full-scale and flight research.

  5. Ares I Scale Model Acoustic Test Lift-Off Acoustics

    NASA Technical Reports Server (NTRS)

    Counter, Douglas D.; Houston, Janie D.

    2011-01-01

    The lift-off acoustic (LOA) environment is an important design factor for any launch vehicle. For the Ares I vehicle, the LOA environments were derived by scaling flight data from other launch vehicles. The Ares I LOA predicted environments are compared to the Ares I Scale Model Acoustic Test (ASMAT) preliminary results.

  6. Acoustic Mechanical Feedthroughs

    NASA Technical Reports Server (NTRS)

    Sherrit, Stewart; Walkemeyer, Phillip; Bao, Xiaoqi; Bar-Cohen, Yoseph; Badescu, Mircea

    2013-01-01

    Electromagnetic motors can have problems when operating in extreme environments. In addition, if one needs to do mechanical work outside a structure, electrical feedthroughs are required to transport the electric power to drive the motor. In this paper, we present designs for driving rotary and linear motors by pumping stress waves across a structure or barrier. We accomplish this by designing a piezoelectric actuator on one side of the structure and a resonance structure that is matched to the piezoelectric resonance of the actuator on the other side. Typically, piezoelectric motors can be designed with high torques and lower speeds without the need for gears. One can also use other actuation materials such as electrostrictive, or magnetostrictive materials in a benign environment and transmit the power in acoustic form as a stress wave and actuate mechanisms that are external to the benign environment. This technology removes the need to perforate a structure and allows work to be done directly on the other side of a structure without the use of electrical feedthroughs, which can weaken the structure, pipe, or vessel. Acoustic energy is pumped as a stress wave at a set frequency or range of frequencies to produce rotary or linear motion in a structure. This method of transferring useful mechanical work across solid barriers by pumping acoustic energy through a resonant structure features the ability to transfer work (rotary or linear motion) across pressure or thermal barriers, or in a sterile environment, without generating contaminants. Reflectors in the wall of barriers can be designed to enhance the efficiency of the energy/power transmission. The method features the ability to produce a bi-directional driving mechanism using higher-mode resonances. There are a variety of applications where the presence of a motor is complicated by thermal or chemical environments that would be hostile to the motor components and reduce life and, in some instances, not be

  7. Dynamic acoustic tractor beams

    NASA Astrophysics Data System (ADS)

    Mitri, F. G.

    2015-03-01

    Pulling a sphere and vibrating it around an equilibrium position by amplitude-modulation in the near-field of a single finite circular piston transducer is theoretically demonstrated. Conditions are found where a fluid hexane sphere (with arbitrary radius) chosen as an example, centered on the axis of progressive propagating waves and submerged in non-viscous water, experiences an attractive (steady) force pulling it towards the transducer, as well as an oscillatory force forcing it to vibrate back-and-forth. Numerical predictions for the dynamic force illustrate the theory and suggest an innovative method in designing dynamic acoustical tractor beams.

  8. The acoustics of snoring.

    PubMed

    Pevernagie, Dirk; Aarts, Ronald M; De Meyer, Micheline

    2010-04-01

    Snoring is a prevalent disorder affecting 20-40% of the general population. The mechanism of snoring is vibration of anatomical structures in the pharyngeal airway. Flutter of the soft palate accounts for the harsh aspect of the snoring sound. Natural or drug-induced sleep is required for its appearance. Snoring is subject to many influences such as body position, sleep stage, route of breathing and the presence or absence of sleep-disordered breathing. Its presentation may be variable within or between nights. While snoring is generally perceived as a social nuisance, rating of its noisiness is subjective and, therefore, inconsistent. Objective assessment of snoring is important to evaluate the effect of treatment interventions. Moreover, snoring carries information relating to the site and degree of obstruction of the upper airway. If evidence for monolevel snoring at the site of the soft palate is provided, the patient may benefit from palatal surgery. These considerations have inspired researchers to scrutinize the acoustic characteristics of snoring events. Similarly to speech, snoring is produced in the vocal tract. Because of this analogy, existing techniques for speech analysis have been applied to evaluate snoring sounds. It appears that the pitch of the snoring sound is in the low-frequency range (<500 Hz) and corresponds to a fundamental frequency with associated harmonics. The pitch of snoring is determined by vibration of the soft palate, while nonpalatal snoring is more 'noise-like', and has scattered energy content in the higher spectral sub-bands (>500 Hz). To evaluate acoustic properties of snoring, sleep nasendoscopy is often performed. Recent evidence suggests that the acoustic quality of snoring is markedly different in drug-induced sleep as compared with natural sleep. Most often, palatal surgery alters sound characteristics of snoring, but is no cure for this disorder. It is uncertain whether the perceived improvement after palatal surgery, as

  9. Quantum positron acoustic waves

    SciTech Connect

    Metref, Hassina; Tribeche, Mouloud

    2014-12-15

    Nonlinear quantum positron-acoustic (QPA) waves are investigated for the first time, within the theoretical framework of the quantum hydrodynamic model. In the small but finite amplitude limit, both deformed Korteweg-de Vries and generalized Korteweg-de Vries equations governing, respectively, the dynamics of QPA solitary waves and double-layers are derived. Moreover, a full finite amplitude analysis is undertaken, and a numerical integration of the obtained highly nonlinear equations is carried out. The results complement our previously published results on this problem.

  10. Wind turbine acoustics

    NASA Technical Reports Server (NTRS)

    Hubbard, Harvey H.; Shepherd, Kevin P.

    1990-01-01

    Available information on the physical characteristics of the noise generated by wind turbines is summarized, with example sound pressure time histories, narrow- and broadband frequency spectra, and noise radiation patterns. Reviewed are noise measurement standards, analysis technology, and a method of characterizing wind turbine noise. Prediction methods are given for both low-frequency rotational harmonics and broadband noise components. Also included are atmospheric propagation data showing the effects of distance and refraction by wind shear. Human perception thresholds, based on laboratory and field tests, are given. Building vibration analysis methods are summarized. The bibliography of this report lists technical publications on all aspects of wind turbine acoustics.

  11. Dynamic acoustic tractor beams

    SciTech Connect

    Mitri, F. G.

    2015-03-07

    Pulling a sphere and vibrating it around an equilibrium position by amplitude-modulation in the near-field of a single finite circular piston transducer is theoretically demonstrated. Conditions are found where a fluid hexane sphere (with arbitrary radius) chosen as an example, centered on the axis of progressive propagating waves and submerged in non-viscous water, experiences an attractive (steady) force pulling it towards the transducer, as well as an oscillatory force forcing it to vibrate back-and-forth. Numerical predictions for the dynamic force illustrate the theory and suggest an innovative method in designing dynamic acoustical tractor beams.

  12. North Pacific Acoustic Laboratory.

    PubMed

    Worcester, Peter F; Spindel, Robert C

    2005-03-01

    A series of long-range acoustic propagation experiments have been conducted in the North Pacific Ocean during the last 15 years using various combinations of low-frequency, wide-bandwidth transmitters and horizontal and vertical line array receivers, including a 2-dimensional array with a maximum vertical aperture of 1400 m and a horizontal aperture of 3600 m. These measurements were undertaken to further our understanding of the physics of low-frequency, broadband propagation and the effects of environmental variability on signal stability and coherence. In this volume some of the results are presented. In the present paper the central issues these experiments have addressed are briefly summarized. PMID:15810685

  13. Acoustic microscopy of living cells.

    PubMed Central

    Hildebrand, J A; Rugar, D; Johnston, R N; Quate, C F

    1981-01-01

    This paper reports preliminary results of the observation by acoustic microscopy of living cells in vitro. The scanning acoustic microscope uses high-frequency sound waves to produce images with submicrometer resolution. The contrast observed in acoustic micrographs of living cells depends on the acoustic properties (i.e., density, stiffness, and attenuation) and on the topographic contour of the cell. Variation in distance separating the acoustic lens and the viewed cell also has a profound effect on the image. When the substratum is located at the focal plane, thick regions of the cell show a darkening that can be related to cellular acoustic attenuation (a function of cytoplasmic viscosity). When the top of the cell is placed near the focal plane, concentric bright and dark rings appear in the image. The location of the rings can be related to cell topography, and the ring contrast can be correlated to the stiffness and density of the cell. In addition, the character of the images of single cells varies dramatically when the substratum upon which they are grown is changed to a different material. By careful selection of the substratum, the information content of the acoustic images can be increased. Our analysis of acoustic images of actively motile cells indicates that leading lamella are less dense or stiff than the quiescent trailing processes of the cells. Images PMID:6940179

  14. Digital Controller For Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Tarver, D. Kent

    1989-01-01

    Acoustic driver digitally controls sound fields along three axes. Allows computerized acoustic levitation and manipulation of small objects for such purposes as containerless processing and nuclear-fusion power experiments. Also used for controlling motion of vibration-testing tables in three dimensions.

  15. Acoustical Environment for Academic Buildings.

    ERIC Educational Resources Information Center

    Lortie, L.J.

    Discussion of the parameters governing noise control and room acoustics are followed by a demonstration on how to achieve a good acoustical environment. Topics emphasized include--(1) design and control objectives, (2) noise sources and propagation, (3) reverberation parameters, (4) noise control factors and parameters, and (5) sound systems. Also…

  16. Acoustic Emissions Reveal Combustion Conditions

    NASA Technical Reports Server (NTRS)

    Ramohalli, D. N. R.; Seshan, P. K.

    1983-01-01

    Turbulent-flame acoustic emissions change with air/fuel ratio variations. Acoustic emissions sensed and processed to detect inefficient operation; control system responds by adjusting fuel/air mixture for greater efficiency. Useful for diagnosis of combustion processes and fuel/air control.

  17. Electronic dummy for acoustical testing

    NASA Technical Reports Server (NTRS)

    Bauer, B. B.; Di Mattia, A. L.; Rosencheck, A. J.; Stern, M.; Torick, E. L.

    1967-01-01

    Electronic Dummy /ED/ used for acoustical testing represents the average male torso from the Xiphoid process upward and includes an acoustic replica of the human head. This head simulates natural flesh, and has an artificial voice and artificial ears that measure sound pressures at the eardrum or the entrance to the ear canal.

  18. Sound Advice on Classroom Acoustics.

    ERIC Educational Resources Information Center

    Sturgeon, Julie

    2003-01-01

    Discusses the importance of acoustic standards in classroom design, presenting an interview with the Acoustical Society of America's (ASA's) standards manager which focuses on reasons for the new ASA standards, the standards document (which was written for K-12 classroom but applies to college classrooms), the need to avoid echo and be able to…

  19. Acoustic Similarity and Dichotic Listening.

    ERIC Educational Resources Information Center

    Benson, Peter

    1978-01-01

    An experiment tests conjectures that right ear advantage (REA) has an auditory origin in competition or interference between acoustically similar stimuli and that feature-sharing effect (FSE) has its origin in assignment of features of phonetically similar stimuli. No effect on the REA for acoustic similarity, and a clear effect of acoustic…

  20. Magnetostriction Measured by Holographic Interferometry with the Simple and Inexpensive "Arrowhead" Setup

    ERIC Educational Resources Information Center

    Ladera, Celso L.; Donoso, Guillermo; Contreras, Johnny H.

    2012-01-01

    Double-exposure holographic interferometry is applied to measure the "linear" or "longitudinal" magnetostriction constant of a soft-ferrite rod. This high-accuracy measurement is done indirectly, by measuring the small rotations of a lever in contact with the rod using double-exposure holographic interferometry implemented with a robust…

  1. The use of correlation interferometry for analysis of phase inhomogeneous environments and surfaces

    NASA Astrophysics Data System (ADS)

    Derzhypolska, L.; Gnatovskiy, O.; Negriyko, A.

    2015-12-01

    In the paper investigated are optically inhomogeneous objects using holographic interferometry, speckle-interferometry and optical correlation. A non-interferometricshift of interference fringes is observed. Shown is that the shift is related to the statistical distribution that describes the optical inhomogeneity of the objects of study.

  2. Determination of effective brain connectivity from functional connectivity using propagator-based interferometry and neural field theory with application to the corticothalamic system

    NASA Astrophysics Data System (ADS)

    Robinson, P. A.

    2014-10-01

    It is shown how to compute both direct and total effective connection matrices (deCMs and teCMs), which embody the strengths of neural connections between regions, from correlation-based functional CMs using propagator-based interferometry, a method that stems from geophysics and acoustics, coupled with the recent identification of deCMs and teCMs with bare and dressed propagators, respectively. The approach incorporates excitatory and inhibitory connections, multiple structures and populations, and measurement effects. The propagator is found for a generalized scalar wave equation derived from neural field theory, and expressed in terms of neural activity correlations and covariances, and wave damping rates. It is then related to correlation matrices that are commonly used to express functional and effective connectivities in the brain. The results are illustrated in analytically tractable test cases.

  3. Opto-acoustic thrombolysis

    DOEpatents

    Celliers, Peter; Da Silva, Luiz; Glinsky, Michael; London, Richard; Maitland, Duncan; Matthews, Dennis; Fitch, Pat

    2000-01-01

    This invention is a catheter-based device for generating an ultrasound excitation in biological tissue. Pulsed laser light is guided through an optical fiber to provide the energy for producing the acoustic vibrations. The optical energy is deposited in a water-based absorbing fluid, e.g. saline, thrombolytic agent, blood or thrombus, and generates an acoustic impulse in the fluid through thermoelastic and/or thermodynamic mechanisms. By pulsing the laser at a repetition rate (which may vary from 10 Hz to 100 kHz) an ultrasonic radiation field can be established locally in the medium. This method of producing ultrasonic vibrations can be used in vivo for the treatment of stroke-related conditions in humans, particularly for dissolving thrombus or treating vasospasm. The catheter can also incorporate thrombolytic drug treatments as an adjunct therapy and it can be operated in conjunction with ultrasonic detection equipment for imaging and feedback control and with optical sensors for characterization of thrombus type and consistency.

  4. Musical acoustics demonstrations

    NASA Astrophysics Data System (ADS)

    Hoekje, P. L.

    2003-10-01

    The ASA Musical Acoustics Demonstrations website (trial version at http://www.bw.edu/~phoekje) includes sound files, video clips, program code listings, and other material for demonstrations related to musical acoustics. Many of the sound demonstrations may be experienced either as expositions, in which the phenomena are explained before they are presented, or as experiments, in which the explanation comes after listeners have had the opportunity to draw their own conclusions. Suggestions are provided for apparatus construction and classroom experiments, as well as for building simple musical instruments. Software is recommended if it is available free and compatible with multiple personal computer operating systems. For example, Audacity (http://audacity.sourceforce.net) is a sound file editor and analyzer that can be used to visually represent sounds and manipulate them. Source files are included for the synthesized sound examples, which were created in Csound (http://csounds.com), so that interested users may create their own variations. Source code is also included for visual demonstrations created in Visual Python and Python (http://www.python.org), an efficient, high level programming language. Suggestions, criticisms, and contributions are always welcome! [Work supported by ASA and Baldwin-Wallace College.

  5. Acoustic source localization.

    PubMed

    Kundu, Tribikram

    2014-01-01

    In this article different techniques for localizing acoustic sources are described and the advantages/disadvantages of these techniques are discussed. Some source localization techniques are restricted to isotropic structures while other methods can be applied to anisotropic structures as well. Some techniques require precise knowledge of the direction dependent velocity profiles in the anisotropic body while other techniques do not require that knowledge. Some methods require accurate values of the time of arrival of the acoustic waves at the receivers while other techniques can function without that information. Published papers introducing various techniques emphasize the advantages of the introduced techniques while ignoring and often not mentioning the limitations and weaknesses of the new techniques. What is lacking in the literature is a comprehensive review and comparison of the available techniques; this article attempts to do that. After reviewing various techniques the paper concludes which source localization technique should be most effective for what type of structure and what the current research needs are. PMID:23870388

  6. MEMS Based Acoustic Array

    NASA Technical Reports Server (NTRS)

    Sheplak, Mark (Inventor); Nishida, Toshikaza (Inventor); Humphreys, William M. (Inventor); Arnold, David P. (Inventor)

    2006-01-01

    Embodiments of the present invention described and shown in the specification aid drawings include a combination responsive to an acoustic wave that can be utilized as a dynamic pressure sensor. In one embodiment of the present invention, the combination has a substrate having a first surface and an opposite second surface, a microphone positioned on the first surface of the substrate and having an input and a first output and a second output, wherein the input receives a biased voltage, and the microphone generates an output signal responsive to the acoustic wave between the first output and the second output. The combination further has an amplifier positioned on the first surface of the substrate and having a first input and a second input and an output, wherein the first input of the amplifier is electrically coupled to the first output of the microphone and the second input of the amplifier is electrically coupled to the second output of the microphone for receiving the output sinual from the microphone. The amplifier is spaced from the microphone with a separation smaller than 0.5 mm.

  7. Acoustic particle acceleration sensors

    SciTech Connect

    Franklin, J.B.; Barry, P.J.

    1996-04-01

    A crossed dipole array provides a directional receiving capability in a relatively small sensor package and is therefore very attractive for many applications in acoustics. Particle velocity measurements on two axes perpendicular to each other are required to provide the dipole signals. These can be obtained directly using particle velocity sensors or via simple transfer functions using acceleration and displacement sensors. Also, the derivative of the acoustic pressure with respect to space provides a signal proportional to the particle acceleration and gives rise to the pressure gradient sensor. Each of these sensors has strengths and drawbacks depending on the frequency regime of interest, the noise background, and whether a point or a line configuration of dipole sensors is desired. In this paper, the performance of acceleration sensors is addressed using a sensor concept developed at DREA. These sensors exploit bending stresses in a cantilever beam of piezoelectric material to obtain wide bandwidth and high sensitivity. Models which predict the acceleration sensitivity, pressure sensitivity, and natural frequency for this type of sensor are described. Experimental results obtained using several different versions of these sensors are presented and compared with theory. The predicted performance of acceleration sensors are compared with that of pressure gradient arrays and particle velocity sensors. {copyright} {ital 1996 American Institute of Physics.}

  8. Opto-acoustic thrombolysis

    SciTech Connect

    Celliers, P.; Silva, L. Da; Glinsky, M.; London, R.; Maitland, D.; Matthews, D.; Fitch, P.

    2000-02-08

    This invention is a catheter-based device for generating an ultrasound excitation in biological tissue. Pulsed laser light is guided through an optical fiber to provide the energy for producing the acoustic vibrations. The optical energy is deposited in a water-based absorbing fluid, e.g. saline, thrombolytic agent, blood or thrombus, and generates an acoustic impulse in the fluid through thermoelastic and/or thermodynamic mechanisms. By pulsing the laser at a repetition rate (which may vary from 10 Hz to 100 kHz) an ultrasonic radiation field can be established locally in the medium. This method of producing ultrasonic vibrations can be used in vivo for the treatment of stroke-related conditions in humans, particularly for dissolving thrombus or treating vasospasm. The catheter can also incorporate thrombolytic drug treatments as an adjunct therapy and it can be operated in conjunction with ultrasonic detection equipment for imaging and feedback control and with optical sensors for characterization of thrombus type and consistency.

  9. Acoustic emission linear pulse holography

    DOEpatents

    Collins, H.D.; Busse, L.J.; Lemon, D.K.

    1983-10-25

    This device relates to the concept of and means for performing Acoustic Emission Linear Pulse Holography, which combines the advantages of linear holographic imaging and Acoustic Emission into a single non-destructive inspection system. This unique system produces a chronological, linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. The innovation is the concept of utilizing the crack-generated acoustic emission energy to generate a chronological series of images of a growing crack by applying linear, pulse holographic processing to the acoustic emission data. The process is implemented by placing on a structure an array of piezoelectric sensors (typically 16 or 32 of them) near the defect location. A reference sensor is placed between the defect and the array.

  10. Acoustic Absorption in Porous Materials

    NASA Technical Reports Server (NTRS)

    Kuczmarski, Maria A.; Johnston, James C.

    2011-01-01

    An understanding of both the areas of materials science and acoustics is necessary to successfully develop materials for acoustic absorption applications. This paper presents the basic knowledge and approaches for determining the acoustic performance of porous materials in a manner that will help materials researchers new to this area gain the understanding and skills necessary to make meaningful contributions to this field of study. Beginning with the basics and making as few assumptions as possible, this paper reviews relevant topics in the acoustic performance of porous materials, which are often used to make acoustic bulk absorbers, moving from the physics of sound wave interactions with porous materials to measurement techniques for flow resistivity, characteristic impedance, and wavenumber.

  11. Differential interferometry with adjustable spatial carrier fringes for turbine blade cascade flow investigations

    NASA Astrophysics Data System (ADS)

    Woisetschläger, J.; Pretzler, G.; Jericha, H.; Mayrhofer, N.; Pirker, H. P.

    Digital evaluated differential interferometry using adjustable spatial carrier fringes was applied to flow measurements in a transonic turbine blade cascade. The interferograms were evaluated using a two-dimensional Fourier Analysis. This evaluation provided density gradient maps of the flow field in a digital form. A specially designed interferometer was used allowing adjustment of sensitivity and superposition of carrier-fringe system separately. This type of interferometer is also highly insensitive to vibration noise. For a turbine blade cooling film a comparison of this type of differential interferometry with holographic interferometry and a Schlieren visualisation is also given. As a result differential interferometry using adjustable spatial carrier fringes and digital fringe analysis gave density-gradient maps similar to Schlieren recordings but of quantitative nature, thus enabling compensation of wave front distortions. Integration of these density gradient maps resulted in density maps which were then compared to recordings done with pulsed holographic interferometry.

  12. Application of Phase Shifted, Laser Feedback Interferometry to Fluid Physics

    NASA Technical Reports Server (NTRS)

    Ovryn, Ben; Eppell, Steven J.; Andrews, James H.; Khaydarov, John

    1996-01-01

    We have combined the principles of phase-shifting interferometry (PSI) and laser-feedback interferometry (LFI) to produce a new instrument that can measure both optical path length (OPL) changes and discern sample reflectivity variations. In LFI, coherent feedback of the incident light either reflected directly from a surface or reflected after transmission through a region of interest will modulate the output intensity of the laser. LFI can yield a high signal-to-noise ratio even for low reflectivity samples. By combining PSI and LFI, we have produced a robust instrument, based upon a HeNe laser, with high dynamic range that can be used to measure either static (dc) or oscillatory changes along the optical path. As with other forms of interferometry, large changes in OPL require phase unwrapping. Conversely, small phase changes are limited by the fraction of a fringe that can be measured. We introduce the phase shifts with an electro-optic modulator (EOM) and use either the Carre or Hariharan algorithms to determine the phase and visibility. We have determined the accuracy and precision of our technique by measuring both the bending of a cantilevered piezoelectric bimorph and linear ramps to the EOM. Using PSI, sub-nanometer displacements can be measured. We have combined our interferometer with a commercial microscope and scanning piezoelectric stage and have measured the variation in OPL and visibility for drops of PDMS (silicone oil) on coated single crystal silicon. Our measurement of the static contact angle agrees with the value of 68 deg stated in the literature.

  13. Investigating the Salton Sea geothermal region using seismic interferometry

    NASA Astrophysics Data System (ADS)

    Matzel, E.

    2011-12-01

    Seismic interferometry has proven to be a powerful method for imaging the Earth's interior. To date, much of the work in seismic interferometry has used ambient noise correlation, which isolates the seismic energy between pairs of seismometers. This has resulted in sharp images of the crust and upper mantle, particularly in areas with dense seismic networks. Curtis et al. (2009) demonstrated that we can reverse the geometry of the problem to focus instead on the energy between pairs of earthquakes. The Virtual Seismometer method (VSM) involves correlating the coda of pairs of events recorded at individual stations and then stacking the results over all stations to obtain an estimate of the Green's function between the sources. By effectively replacing each earthquake with a "virtual station" recording all the others, VSM isolates the portion of the data that is sensitive to the source region and significantly improves our ability to see into tectonically active features. VSM is proving to be a powerful method for studying individual earthquakes and the source region. Using this technique, we are able to recover the expected Green's function between pairs of earthquakes, relocate the earthquakes in time and space, measure the source-time function and source magnitude, and finally image the structure along the path between them. Here we investigate the capability of seismic interferometry for geothermal studies. First, we apply ambient noise correlation to dozens of vertical component seismic stations in Southern California with a particular focus on the Salton Sea geothermal fields. We use these correlations to create a 3 dimensional model of the crust in the region. We then apply VSM to well located earthquakes and explosions in the region to determine the scalability of that technique to very small magnitude events recorded by nearby seismic networks. Of particular interest are the highest frequencies and smallest magnitudes the VSM can resolve.

  14. Research on stitching interferometry aspheric surface with correcting systemic aberration

    NASA Astrophysics Data System (ADS)

    Qiao, Yujing; Han, Guihua

    2010-10-01

    Sub-aperture stitching interferometry was originally used for measurement of large-diameter plane and spherical, it is a technological means that uses small-caliber interferometer to test each parts of optical component, and then all the subaperture data are combined or stitched together to create a map of the full surface. Correcting adjust errors of three directions is currently stitching algorithm for realizing the stitching testing aspheric surface. But without spatial analysis for bias errors of positioning mechanism, we can't know exactly the actual appearance of bias errors, consequently will not be able to implement a accuracy stitching.. Because the accuracy of individual stitching can't meet the accuracy requirements, the test result of stitching interferometry aspheric surface will not meet requirements of accuracy due to the errors accumulation. Correcting systemic aberration method is presented to solve the problem mentioned above. It is based on the analysis of the actual impact appearance of location components' bias error in interferometry. The actual appearance is exactly the same after comparing with the Seidle aberration. a correction bias errors model of stitching measure is found based on the analysis, and it proposed an accuracy stitching measurement for quadric surface measurement. It gets the stitching coefficients with least square fitting method, and acquires the estimate values of bias errors in sub-aperture stitching components, and corrects the high-order systemic aberration, therefore improve the fitting accuracy in sub-apertures overlap zone. The experiment result shows, the stitching accuracy of this stitching method is higher than traditional stitching method.

  15. Experimental Investigation of Textile Composite Materials Using Moire Interferometry

    NASA Technical Reports Server (NTRS)

    Ifju, Peter G.

    1995-01-01

    The viability as an efficient aircraft material of advanced textile composites is currently being addressed in the NASA Advanced Composites Technology (ACT) Program. One of the expected milestones of the program is to develop standard test methods for these complex material systems. Current test methods for laminated composites may not be optimum for textile composites, since the architecture of the textile induces nonuniform deformation characteristics on the scale of the smallest repeating unit of the architecture. The smallest repeating unit, also called the unit cell, is often larger than the strain gages used for testing of tape composites. As a result, extending laminated composite test practices to textiles can often lead to pronounced scatter in material property measurements. It has been speculated that the fiber architectures produce significant surface strain nonuniformities, however, the magnitudes were not well understood. Moire interferometry, characterized by full-field information, high displacement sensitivity, and high spatial resolution, is well suited to document the surface strain on textile composites. Studies at the NASA Langley Research Center on a variety of textile architectures including 2-D braids and 3-D weaves, has evidenced the merits of using moire interferometry to guide in test method development for textile composites. Moire was used to support tensile testing by validating instrumentation practices and documenting damage mechanisms. It was used to validate shear test methods by mapping the full-field deformation of shear specimens. Moire was used to validate open hole tension experiments to determine the strain concentration and compare then to numeric predictions. It was used for through-the-thickness tensile strength test method development, to verify capabilities for testing of both 2-D and 3-D material systems. For all of these examples, moire interferometry provided vision so that test methods could be developed with less

  16. Measurements of Laser Imprinting Using 2-D Velocity Interferometry

    NASA Astrophysics Data System (ADS)

    Boehly, T. R.; Fiksel, G.; Hu, S. X.; Goncharov, V. N.; Sangster, T. C.; Celliers, P. M.

    2014-10-01

    Evaluating laser imprinting and its effect on target performance is critical to direct-drive inertial confinement fusion research. Using high-resolution velocity interferometry, we measure modulations in the velocity of shock waves produced by the 351-nm beams on OMEGA. These modulations result from nonuniformities in the drive laser beams. We use these measurements to evaluate the effect on imprinting of multibeam irradiation and metal layers on both plastic and cryogenic deuterium targets driven with 100-ps pulses. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  17. IMAP: Interferometry for Material Property Measurement in MEMS

    SciTech Connect

    Jensen, B.D.; Miller, S.L.; de Boer, M.P.

    1999-03-10

    An interferometric technique has been developed for non-destructive, high-confidence, in-situ determination of material properties in MEMS. By using interferometry to measure the full deflection curves of beams pulled toward the substrate under electrostatic loads, the actual behavior of the beams has been modeled. No other method for determining material properties allows such detailed knowledge of device behavior to be gathered. Values for material properties and non-idealities (such as support post compliance) have then been extracted which minimize the error between the measured and modeled deflections. High accuracy and resolution have been demonstrated, allowing the measurements to be used to enhance process control.

  18. The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII)

    NASA Technical Reports Server (NTRS)

    Rinehart, Stephen A.

    2010-01-01

    Astronomical studies at infrared wavelengths have dramatically improved our understanding of the universe. The relatively low angular resolution of these missions, however, is insufficient to resolve the physical scale on which mid-to far-infrared emission arises. We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII), an eight-meter Michelson interferometer to fly on a high-altitude balloon. BETTII's spectral-spatial capability, provided by an instrument using double-Fourier techniques, will address key questions about the nature of disks in young star clusters and active galactic nuclei and the envelopes of evolved stars. BETTII will also lay the technological groundwork for future space interferometers.

  19. The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII)

    NASA Technical Reports Server (NTRS)

    Rinehart, Stephen

    2012-01-01

    The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) is an 8-meter baseline far-infrared interferometer to fly on a high altitude balloon. BETTII uses a double-Fourier Michelson interferometer to simultaneously obtain spatial and spectral information on science targets; the long baseline provides subarcsecond angular resolution, a capability unmatched by other far-infrared facilities. Here, we present key aspects of the overall design of the mission and provide an overview of the current status of the project. We also discuss briefly the implications of this experiment for future space-based far-infrared interferometers.

  20. BETTII: The Balloon Experimental Twin Telescope for Infrared Interferometry

    NASA Technical Reports Server (NTRS)

    Rinehart, Stephen

    2011-01-01

    Astronomical studies at infrared wavelengths have dramatically improved our understanding the universe. The relatively low angular resolution of these missions, however, is insufficient to resolve the physical scale on which mid-to far-infrared emission arises. We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII),8oeight-meter Michelson interferometer to fly on a high-altitude balloon. BETTII's spectral-spatial capability, provided by an instrument using double-Fourier techniques, will address key questions about the nature of disks io young star clusters and active galactic nuclei and the envelopes of evolved stars. BETTII will also lay the technological groundwork for future space interferometers.