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Sample records for acoustical holography based

  1. A refined wideband acoustical holography based on equivalent source method

    PubMed Central

    Ping, Guoli; Chu, Zhigang; Xu, Zhongming; Shen, Linbang

    2017-01-01

    This paper is concerned with acoustical engineering and mathematical physics problem for the near-field acoustical holography based on equivalent source method (ESM-based NAH). An important mathematical physics problem in ESM-based NAH is to solve the equivalent source strength, which has multiple solving algorithms, such as Tikhonov regularization ESM (TRESM), iterative weighted ESM (IWESM) and steepest descent iteration ESM (SDIESM). To explore a new solving algorithm which can achieve better reconstruction performance in wide frequency band, a refined wideband acoustical holography (RWAH) is proposed. RWAH adopts IWESM below a transition frequency and switches to SDIESM above that transition frequency, and the principal components of input data in RWAH have been truncated. Further, the superiority of RWAH is verified by the comparison of comprehensive performance of TRESM, IWESM, SDIESM and RWAH. Finally, the experiments are conducted, confirming that RWAH can achieve better reconstruction performance in wide frequency band. PMID:28266531

  2. A refined wideband acoustical holography based on equivalent source method

    NASA Astrophysics Data System (ADS)

    Ping, Guoli; Chu, Zhigang; Xu, Zhongming; Shen, Linbang

    2017-03-01

    This paper is concerned with acoustical engineering and mathematical physics problem for the near-field acoustical holography based on equivalent source method (ESM-based NAH). An important mathematical physics problem in ESM-based NAH is to solve the equivalent source strength, which has multiple solving algorithms, such as Tikhonov regularization ESM (TRESM), iterative weighted ESM (IWESM) and steepest descent iteration ESM (SDIESM). To explore a new solving algorithm which can achieve better reconstruction performance in wide frequency band, a refined wideband acoustical holography (RWAH) is proposed. RWAH adopts IWESM below a transition frequency and switches to SDIESM above that transition frequency, and the principal components of input data in RWAH have been truncated. Further, the superiority of RWAH is verified by the comparison of comprehensive performance of TRESM, IWESM, SDIESM and RWAH. Finally, the experiments are conducted, confirming that RWAH can achieve better reconstruction performance in wide frequency band.

  3. Acoustic holography. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Reed, W. E.

    1980-07-01

    Aspects of acoustic holography are covered in this bibliography of Federally funded research. Theory, equipment design, uses, and imaging techniques are presented. The applications include underwater and underground object locating, structural geology and tectonics, sonar imaging, non destructive testing, antenna radiation patterns, nuclear reactor inspection, remote sensing, and use in medical examination. This updated bibliography contains 166 citations, 15 of which are new entries to the previous edition.

  4. Nearfield Acoustical Holography

    NASA Astrophysics Data System (ADS)

    Hayek, Sabih I.

    Nearfield acoustical holography (NAH) is a method by which a set of acoustic pressure measurements at points located on a specific surface (called a hologram) can be used to image sources on vibrating surfaces on the acoustic field in three-dimensional space. NAH data are processed to take advantage of the evanescent wavefield to image sources that are separated less that one-eighth of a wavelength.

  5. Underwater patch near-field acoustical holography based on particle velocity and vector hydrophone array

    NASA Astrophysics Data System (ADS)

    Hu, Bo; Yang, DeSen; Li, SiChun; Sun, Yu; Mo, ShiQi; Shi, ShengGuo

    2012-11-01

    One-step patch near-field acoustical holography (PNAH) is a powerful tool for identifying noise sources from the partially known sound pressure field. The acoustical property to be reconstructed on the surface of interest is related to the partially measured pressure on the hologram surface in terms of sampling and bandlimiting matrices, which cost more in computation. A one-step procedure based on measuring of the normal component of the particle velocity is described, including the mathematical formulation. The numerical simulation shows that one-step PNAH based on particle velocity can obtain more accurately reconstructed results and it is also less sensitive to noise than the method based on pressure. These findings are confirmed by an underwater near-field acoustical holography experiment conducted with a vector hydrophone array. The experimental results have illustrated the high performance of one-step PNAH based on particle velocity in the reconstruction of sound field and the advantages of a vector hydrophone array in an underwater near-field measurement.

  6. Research on Diagnosing the Gearbox Faults Based on Near Field Acoustic Holography

    NASA Astrophysics Data System (ADS)

    Jiang, W. K.; Hou, J. J.; Xing, J. T.

    2011-07-01

    The gearbox fault diagnosis was developed for some decades. The current diagnosis techniques were mostly based on analyzing the shell vibration signals especially close to the bearing seat of gearbox. In order to utilize the spatial distribution information of fault signal, the near field acoustic holography (NAH) is employed for the condition monitoring and fault diagnosis of the gearbox in this presentation. The distribution images of sound pressure on the surface of gearbox are reconstructed by NAH, and the feature extraction and pattern recognition can be made by image processing techniques. A gearbox is studied in a semi-anechoic chamber to verify the fault diagnosis technique based on NAH. The pitting and partial broken tooth faults of gears are artificially made on one gear as the fault statuses, and the differences of acoustic images among normal and fault working states under the idling condition are analyzed. It can be found that the acoustic images of gearbox in the three different situations change regularly, and the main sound sources can be recognized from the acoustic images which also contain rich diagnosis information. After feature extraction of the acoustic images, the pattern reorganization technique is employed for diagnosis. The results indicate that this diagnosis procedure based on acoustic images is available and feasible for the gearbox fault diagnosis.

  7. Transient nearfield acoustic holography based on an interpolated time-domain equivalent source method.

    PubMed

    Zhang, Xiao-Zheng; Bi, Chuan-Xing; Zhang, Yong-Bin; Xu, Liang

    2011-09-01

    Transient nearfield acoustic holography based on an interpolated time-domain equivalent source method (ESM) is proposed to reconstruct transient acoustic fields directly in the time domain. Since the equivalent source strengths solved by the traditional time-domain ESM formulation cannot be used to reconstruct the pressure on the source surface directly, an interpolation function is introduced to develop an interpolated time-domain ESM formulation which permits one to deduce an iterative reconstruction process. As the reconstruction process is ill-conditioned and especially there exists a cumulative effect of errors, the Tikhonov regularization is used to stabilize the process. Numerical examples of reconstructing transient acoustic fields from a baffled planar piston, an impulsively accelerating sphere and a cube box, respectively, demonstrate that the proposed method not only can effectively reconstruct transient acoustic fields in the time domain, but also can visualize acoustic fields in the space domain. And, in the first numerical example, the cumulative effect of errors and the validity of using the Tikhonov regularization to suppress the errors are described.

  8. Acoustic emission linear pulse holography

    SciTech Connect

    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.

  9. Underwater hybrid near-field acoustical holography based on the measurement of vector hydrophone array

    NASA Astrophysics Data System (ADS)

    Hu, Bo; Yang, Desen; Sun, Yu

    2010-06-01

    Hybrid near-field acoustical holography (NAH) is developed for reconstructing acoustic radiation from a cylindrical source in a complex underwater environment. In hybrid NAH, we combine statistically optimized near-field acoustical holography (SONAH) and broadband acoustical holography from intensity measurements (BAHIM) to reconstruct the underwater cylindrical source field. First, the BAHIM is utilized to regenerate as much acoustic pressures on the hologram surface as necessary, and then the acoustic pressures are taken as input to the formulation implemented numerically by SONAH. The main advantages of this technology are that the complex pressure on the hologram surface can be reconstructed without reference signal, and the measurement array can be smaller than the source, thus the practicability and efficiency of this technology are greatly enhanced. Numerical examples of a cylindrical source are demonstrated. Test results show that hybrid NAH can yield a more accurate reconstruction than conventional NAH. Then, an experiment has been carried out with a vector hydrophone array. The experimental results show the advantage of hybrid NAH in the reconstruction of an acoustic field and the feasibility of using a vector hydrophone array in an underwater NAH measurement, as well as the identification and localization of noise sources.

  10. Experimental study of the mapping relationship based near-field acoustic holography with spherical fundamental solutions

    NASA Astrophysics Data System (ADS)

    Wu, Haijun; Jiang, Weikang

    2017-04-01

    This paper is a consequent work of the previously proposed mapping relationship based near-field acoustic holography (MRS-based NAH), [H.J.Wu W.K. Jiang and H.B. Zhang, JSV, 373:66-88, 2016]. It is devoted to the performance study of its practical application with error analysis and experimental validation. Two types of errors, the truncation errors due to the limited number of participant modes, and the inevitable measurement errors caused by uncertainties in the experiment, are considered in the analysis. The influences of the errors on the performance of MRS-based NAH are systematically investigated. First of all, expression of the relative reconstruction error of the pressure energy is derived based on the two types of errors. An approach is developed to estimate the lower and upper bounds of the relative error. It gives a guide to predict the error for a reconstruction under the condition that the truncation error and the signal-to-noise ratio are given. Then, the condition number of the inverse operator is investigated to measure the sensitivity of the reconstruction to the input errors. Asymptotic expressions of the condition number for a special case, conformal spherical model and hologram, are obtained, which indicates the condition number has a geometric growth with the number of participant modes. Numerical examples with different kinds of errors are elaborately designed to validate the stability as well as the correctness of the error analysis. At last, the MRS-based NAH is further examined and verified by a physical experiment, a vibrating cubic model reconstructed from measurement on a spherical hologram. A satisfied agreement with the directly measured pressure on a validation surface is observed for both quantity and distribution of the reconstructed pressure.

  11. On optimal retreat distance for the equivalent source method-based nearfield acoustical holography.

    PubMed

    Bai, Mingsian R; Chen, Ching-Cheng; Lin, Jia-Hong

    2011-03-01

    As a basic form of the equivalent source method (ESM) that is used to nearfield acoustical holography (NAH) problems, discrete monopoles are utilized to represent the sound field of interest. When setting up the virtual source distribution, it is vital to maintain a "retreat distance" between the virtual sources and the actual source surface such that reconstruction would not suffer from singularity problems. However, one cannot increase the distance without bound because of the ill-posedness inherent in the reconstruction process with large distance. In prior research, 1-2 times lattice spacing, or the inter-element distance of microphones, is generally recommended as retreat distance in using the ESM-based NAH. While this rule has shown to yield good results in many cases, the optimal choice is a complicated issue that depends on frequency, geometry of the physical source, content of evanescent waves, distribution of sensors and virtual sources, etc. This paper deals about attaining the best compromise between the reconstruction errors induced by the point source singularity; the reconstruction ill-posedness is an interesting problem in its own right. The paper revisits this issue, with the aid of an optimization algorithm based on the golden section search and parabolic interpolation. Numerical simulations were conducted for a baffled planar piston source and a spherically baffled piston source. The results revealed that the retreat distance appropriate for the ESM ranged from 0.4 to 0.5 times the spacing for the planar piston, while from 0.8 to 1.7 times average spacing for the spherical piston. Experiments carried out for a vibrating aluminum plate also revealed that the retreat distance with 0.5 times the spacing yielded better reconstructed velocity than those with 1/20 and 1 times the spacing.

  12. Complete de-Dopplerization and acoustic holography for external noise of a high-speed train.

    PubMed

    Yang, Diange; Wen, Junjie; Miao, Feng; Wang, Ziteng; Gu, Xiaoan; Lian, Xiaomin

    2016-09-01

    Identification and measurement of moving sound sources are the bases for vehicle noise control. Acoustic holography has been applied in successfully identifying the moving sound source since the 1990s. However, due to the high demand for the accuracy of holographic data, currently the maximum velocity achieved by acoustic holography is just above 100 km/h. The objective of this study was to establish a method based on the complete Morse acoustic model to restore the measured signal in high-speed situations, and to propose a far-field acoustic holography method applicable for high-speed moving sound sources. Simulated comparisons of the proposed far-field acoustic holography with complete Morse model, the acoustic holography with simplified Morse model and traditional delay-and-sum beamforming were conducted. Experiments with a high-speed train running at the speed of 278 km/h validated the proposed far-field acoustic holography. This study extended the applications of acoustic holography to high-speed situations and established the basis for quantitative measurements of far-field acoustic holography.

  13. A gearbox fault diagnosis scheme based on near-field acoustic holography and spatial distribution features of sound field

    NASA Astrophysics Data System (ADS)

    Lu, Wenbo; Jiang, Weikang; Yuan, Guoqing; Yan, Li

    2013-05-01

    Vibration signal analysis is the main technique in machine condition monitoring or fault diagnosis, whereas in some cases vibration-based diagnosis is restrained because of its contact measurement. Acoustic-based diagnosis (ABD) with non-contact measurement has received little attention, although sound field may contain abundant information related to fault pattern. A new scheme of ABD for gearbox based on near-field acoustic holography (NAH) and spatial distribution features of sound field is presented in this paper. It focuses on applying distribution information of sound field to gearbox fault diagnosis. A two-stage industrial helical gearbox is experimentally studied in a semi-anechoic chamber and a lab workshop, respectively. Firstly, multi-class faults (mild pitting, moderate pitting, severe pitting and tooth breakage) are simulated, respectively. Secondly, sound fields and corresponding acoustic images in different gearbox running conditions are obtained by fast Fourier transform (FFT) based NAH. Thirdly, by introducing texture analysis to fault diagnosis, spatial distribution features are extracted from acoustic images for capturing fault patterns underlying the sound field. Finally, the features are fed into multi-class support vector machine for fault pattern identification. The feasibility and effectiveness of our proposed scheme is demonstrated on the good experimental results and the comparison with traditional ABD method. Even with strong noise interference, spatial distribution features of sound field can reliably reveal the fault patterns of gearbox, and thus the satisfactory accuracy can be obtained. The combination of histogram features and gray level gradient co-occurrence matrix features is suggested for good diagnosis accuracy and low time cost.

  14. Acoustic-emission linear-pulse holography

    SciTech Connect

    Collins, H.D.; Lemon, D.K.; Busse, L.J.

    1982-06-01

    This paper describes Acoustic Emission Linear Pulse Holography which combines the advantages of linear imaging and acoustic emission into a single NDE inspection system. This unique system produces a chronological linear holographic image of a flaw by utilizing the acoustic energy emitted during crack growth. Conventional linear holographic imaging uses an ultrasonic transducer to transmit energy into the volume being imaged. When the crack or defect reflects that energy, the crack acts as a new source of acoustic waves. To formulate an image of that source, a receiving transducer is scanned over the volume of interest and the phase of the received signals is measured at successive points on the scan. The innovation proposed here is the utilization of the crack generated acoustic emission as the acoustic source and generation of a line image of the crack as it grows. A thirty-two point sampling array is used to construct phase-only linear holograms of simulated acoustic emission sources on large metal plates. The phases are calculated using the pulse time-of-flight (TOF) times from the reference transducer to the array of receivers. Computer reconstruction of the image is accomplished using a one-dimensional FFT algorithm (i.e., backward wave). Experimental results are shown which graphically illustrate the unique acoustic emission images of a single point and a linear crack in a 100 mm x 1220 mm x 1220 mm aluminum plate.

  15. Acoustic emission linear pulse holography

    DOEpatents

    Collins, H. Dale; Busse, Lawrence J.; Lemon, Douglas K.

    1985-01-01

    Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.

  16. Acoustic emission linear pulse holography

    SciTech Connect

    Collins, H. D.; Busse, L. J.; Lemon, D. K.

    1985-07-30

    Defects in a structure are imaged as they propagate, using their emitted acoustic energy as a monitored source. Short bursts of acoustic energy propagate through the structure to a discrete element receiver array. A reference timing transducer located between the array and the inspection zone initiates a series of time-of-flight measurements. A resulting series of time-of-flight measurements are then treated as aperture data and are transferred to a computer for reconstruction of a synthetic linear holographic image. The images can be displayed and stored as a record of defect growth.

  17. Nearfield acoustic holography. I - Theory of generalized holography and the development of NAH

    NASA Technical Reports Server (NTRS)

    Maynard, J. D.; Williams, E. G.; Lee, Y.

    1985-01-01

    Because its underlying principles are so fundamental, holography has been studied and applied in many areas of science. Recently, a technique has been developed which takes the maximum advantage of the fundamental principles and extracts much more information from a hologram than is customarily associated with such a measurement. In this paper the fundamental principles of holography are reviewed, and a sound radiation measurement system, called nearfield acoustic holography (NAH), which fully exploits the fundamental principles, is described.

  18. Krylov subspace iterative methods for boundary element method based near-field acoustic holography.

    PubMed

    Valdivia, Nicolas; Williams, Earl G

    2005-02-01

    The reconstruction of the acoustic field for general surfaces is obtained from the solution of a matrix system that results from a boundary integral equation discretized using boundary element methods. The solution to the resultant matrix system is obtained using iterative regularization methods that counteract the effect of noise on the measurements. These methods will not require the calculation of the singular value decomposition, which can be expensive when the matrix system is considerably large. Krylov subspace methods are iterative methods that have the phenomena known as "semi-convergence," i.e., the optimal regularization solution is obtained after a few iterations. If the iteration is not stopped, the method converges to a solution that generally is totally corrupted by errors on the measurements. For these methods the number of iterations play the role of the regularization parameter. We will focus our attention to the study of the regularizing properties from the Krylov subspace methods like conjugate gradients, least squares QR and the recently proposed Hybrid method. A discussion and comparison of the available stopping rules will be included. A vibrating plate is considered as an example to validate our results.

  19. Cylindrical acoustical holography applied to full-scale jet noise.

    PubMed

    Wall, Alan T; Gee, Kent L; Neilsen, Tracianne B; Krueger, David W; James, Michael M

    2014-09-01

    Near-field acoustical holography methods are used to predict sound radiation from an engine installed on a high-performance military fighter aircraft. Cylindrical holography techniques are an efficient approach to measure the large and complex sound fields produced by full-scale jets. It is shown that a ground-based, one-dimensional array of microphones can be used in conjunction with a cylindrical wave function field representation to provide a holographic reconstruction of the radiated sound field at low frequencies. In the current work, partial field decomposition methods and numerical extrapolation of data beyond the boundaries of the hologram aperture are required prior to holographic projection. Predicted jet noise source distributions and directionality are shown for four frequencies between 63 and 250 Hz. It is shown that the source distribution narrows and moves upstream, and that radiation directionality shifts toward the forward direction, with increasing frequency. A double-lobe feature of full-scale jet radiation is also demonstrated.

  20. Digital holography based submicron thermometry.

    PubMed

    Moradi, Amin; Akhlaghi, Ehsan A; Hajizedeh, Faegheh; Reihani, S Nader S

    2016-12-12

    Here we introduce a phase-shifting digital holography-based method to determine the temperature profile around an irradiated (sub-)micron spherical bead. The method utilizes a Mach-Zehnder interferometer implemented into an open setup microscope. The results of irradiated gold spheres with diameter of 400 nm and also silver-coated micron-sized silica beads embedded in silicone oil are presented. We show that the applied method is able to accurately determine the surface temperature with accuracy of 1 °C. Our experimental results perfectly confirm the theoretical prediction of temperature profile around the irradiated bead.

  1. Identification of vibration excitations from acoustic measurements using near field acoustic holography and the force analysis technique

    NASA Astrophysics Data System (ADS)

    Pézerat, C.; Leclère, Q.; Totaro, N.; Pachebat, M.

    2009-10-01

    This study presents a method of using acoustic holography and the force analysis technique to identify vibration sources from radiated noise measurements. The structure studied is a plate excited by a shaker on which three measurements were performed: the first is a reference measurement of plate velocity obtained by scanning laser vibrometry, the second is based on sound pressure measurements in the near field of the structure, and the third is the measurement of normal acoustic velocities by using a p-U probe recently developed by Microflown Technologies. This was followed by the application of classical NAH, known as pressure-to-velocity holography and velocity-to-velocity holography to predict the plate velocity field from acoustic measurements at distances of 1 and 5 cm. Afterwards, the force analysis technique, also known as the RIFF technique, is applied with these five data sets. The principle is to inject the displacement field of the structure into its equation of motion and extract the resulting force distribution. This technique requires regularization done by a low-pass filter in the wavenumber domain. Apart from pressure-to-velocity holography at 5 cm, the reconstructed force distribution allows localizing the excitation point in the measurement area. FAT regularization is also shown to improve results as its cutoff wavenumber is optimized with the natural wavenumber of the plate. Lastly, quantitative force values are extracted from force distributions at all frequencies of the band 0-4 kHz studied and compared with the force spectrum measured directly by a piezoelectric sensor.

  2. Regularization methods for near-field acoustical holography.

    PubMed

    Williams, E G

    2001-10-01

    The reconstruction of the pressure and normal surface velocity provided by near-field acoustical holography (NAH) from pressure measurements made near a vibrating structure is a linear, ill-posed inverse problem due to the existence of strongly decaying, evanescentlike waves. Regularization provides a technique of overcoming the ill-posedness and generates a solution to the linear problem in an automated way. We present four robust methods for regularization; the standard Tikhonov procedure along with a novel improved version, Landweber iteration, and the conjugate gradient approach. Each of these approaches can be applied to all forms of interior or exterior NAH problems; planar, cylindrical, spherical, and conformal. We also study two parameter selection procedures, the Morozov discrepancy principle and the generalized cross validation, which are crucial to any regularization theory. In particular, we concentrate here on planar and cylindrical holography. These forms of NAH which rely on the discrete Fourier transform are important due to their popularity and to their tremendous computational speed. In order to use regularization theory for the separable geometry problems we reformulate the equations of planar, cylindrical, and spherical NAH into an eigenvalue problem. The resulting eigenvalues and eigenvectors couple easily to regularization theory, which can be incorporated into the NAH software with little sacrifice in computational speed. The resulting complete automation of the NAH algorithm for both separable and nonseparable geometries overcomes the last significant hurdle for NAH.

  3. Near-field acoustical holography of military jet aircraft noise

    NASA Astrophysics Data System (ADS)

    Wall, Alan T.; Gee, Kent L.; Neilsen, Tracianne; Krueger, David W.; Sommerfeldt, Scott D.; James, Michael M.

    2010-10-01

    Noise radiated from high-performance military jet aircraft poses a hearing-loss risk to personnel. Accurate characterization of jet noise can assist in noise prediction and noise reduction techniques. In this work, sound pressure measurements were made in the near field of an F-22 Raptor. With more than 6000 measurement points, this is the most extensive near-field measurement of a high-performance jet to date. A technique called near-field acoustical holography has been used to propagate the complex pressure from a two- dimensional plane to a three-dimensional region in the jet vicinity. Results will be shown and what they reveal about jet noise characteristics will be discussed.

  4. Acoustic holography as a metrological tool for characterizing medical ultrasound sources and fields

    PubMed Central

    Sapozhnikov, Oleg A.; Tsysar, Sergey A.; Khokhlova, Vera A.; Kreider, Wayne

    2015-01-01

    Acoustic holography is a powerful technique for characterizing ultrasound sources and the fields they radiate, with the ability to quantify source vibrations and reduce the number of required measurements. These capabilities are increasingly appealing for meeting measurement standards in medical ultrasound; however, associated uncertainties have not been investigated systematically. Here errors associated with holographic representations of a linear, continuous-wave ultrasound field are studied. To facilitate the analysis, error metrics are defined explicitly, and a detailed description of a holography formulation based on the Rayleigh integral is provided. Errors are evaluated both for simulations of a typical therapeutic ultrasound source and for physical experiments with three different ultrasound sources. Simulated experiments explore sampling errors introduced by the use of a finite number of measurements, geometric uncertainties in the actual positions of acquired measurements, and uncertainties in the properties of the propagation medium. Results demonstrate the theoretical feasibility of keeping errors less than about 1%. Typical errors in physical experiments were somewhat larger, on the order of a few percent; comparison with simulations provides specific guidelines for improving the experimental implementation to reduce these errors. Overall, results suggest that holography can be implemented successfully as a metrological tool with small, quantifiable errors. PMID:26428789

  5. Acoustic holography as a metrological tool for characterizing medical ultrasound sources and fields.

    PubMed

    Sapozhnikov, Oleg A; Tsysar, Sergey A; Khokhlova, Vera A; Kreider, Wayne

    2015-09-01

    Acoustic holography is a powerful technique for characterizing ultrasound sources and the fields they radiate, with the ability to quantify source vibrations and reduce the number of required measurements. These capabilities are increasingly appealing for meeting measurement standards in medical ultrasound; however, associated uncertainties have not been investigated systematically. Here errors associated with holographic representations of a linear, continuous-wave ultrasound field are studied. To facilitate the analysis, error metrics are defined explicitly, and a detailed description of a holography formulation based on the Rayleigh integral is provided. Errors are evaluated both for simulations of a typical therapeutic ultrasound source and for physical experiments with three different ultrasound sources. Simulated experiments explore sampling errors introduced by the use of a finite number of measurements, geometric uncertainties in the actual positions of acquired measurements, and uncertainties in the properties of the propagation medium. Results demonstrate the theoretical feasibility of keeping errors less than about 1%. Typical errors in physical experiments were somewhat larger, on the order of a few percent; comparison with simulations provides specific guidelines for improving the experimental implementation to reduce these errors. Overall, results suggest that holography can be implemented successfully as a metrological tool with small, quantifiable errors.

  6. Acoustic Holography of the Solar Convection Zone with SOHO-MDI Observations

    NASA Technical Reports Server (NTRS)

    Lindsey, Charles

    2005-01-01

    The original grant with the title stated above was NAG5-10984, awarded to the Solar Physics Research Corporation (SPRC) in July, 2001, and was to be a three-year project. The basic theme of the project was the development and application of computational seismic holography for imaging, diagnostics, and monitoring of magnetic anomalies beneath active regions, in the deep solar interior, and on the Sun's far surface. The project was roughly separated into the following five tasks: (1) A holographic survey of active regions. (2) p-Mode absorption diagnostics of magnetic regions. (3) Acoustic modeling of the shallow subphotospheres of active regions and the quiet-Sun supergranulation based on phase-correlation seismic holography. (4) Seismic holography of the deep convection zone. (5) Improvements in holographic imaging of the far surface of the Sun. Following the death of Karen Harvey, President of SPRC, during the first year, the grant was transferred to Northwest Research Associates as NAG5-12901. Substantial but progress had been made on most of the above tasks in the first year under NAG5-10984, but none were completed. This work was continued under NAG5-12901.

  7. Holography.

    ERIC Educational Resources Information Center

    Klein, H. Arthur

    Holography is a process which numbers among its many applications the creation of holograms--unique three dimensional photographs that show spatial relations and shifts just as they exist in reality. This book recounts the history of holography, tracing its development from Euclid's theory of light rays through Huygens' theory of wave motion to…

  8. A sparse equivalent source method for near-field acoustic holography.

    PubMed

    Fernandez-Grande, Efren; Xenaki, Angeliki; Gerstoft, Peter

    2017-01-01

    This study examines a near-field acoustic holography method consisting of a sparse formulation of the equivalent source method, based on the compressive sensing (CS) framework. The method, denoted Compressive-Equivalent Source Method (C-ESM), encourages spatially sparse solutions (based on the superposition of few waves) that are accurate when the acoustic sources are spatially localized. The importance of obtaining a non-redundant representation, i.e., a sensing matrix with low column coherence, and the inherent ill-conditioning of near-field reconstruction problems is addressed. Numerical and experimental results on a classical guitar and on a highly reactive dipole-like source are presented. C-ESM is valid beyond the conventional sampling limits, making wide-band reconstruction possible. Spatially extended sources can also be addressed with C-ESM, although in this case the obtained solution does not recover the spatial extent of the source.

  9. Analytical study of acousto/optical holography-interfacing methods for acoustical and optical holography NDT research

    NASA Technical Reports Server (NTRS)

    El-Sum, H. M. A.

    1976-01-01

    The international status of the art of acousto optical imaging techniques adaptable to nondestructive testing and, interfacing methods for acoustical and optical holography in nondestructive testing research are studied. Evaluation of 20 different techniques encompassed investigation of varieties of detectors and detection schemes, all of which are described and summarized. Related investigation is reported in an Appendix. Important remarks on image quality, factors to be considered in designing a particular system, and conclusions and recommendations are presented. Three bibliographies are included.

  10. Haptic Holography: Acoustic Space and the Evolution of the Whole Message

    NASA Astrophysics Data System (ADS)

    Logan, N.

    2013-02-01

    The paper argues that the Haptic Holography Work Station is an example of a medium that fit's with McLuhan's notion of Acoustic Space, that is it is a medium which stimulates more than one sense of perception at a time. As a result, the Haptic Holography Work Station transmits information about the subject much more rapidly than other media that precedes it, be it text, photography or television.

  11. Investigation of an acoustical holography system for real-time imaging

    NASA Astrophysics Data System (ADS)

    Fecht, Barbara A.; Andre, Michael P.; Garlick, George F.; Shelby, Ronald L.; Shelby, Jerod O.; Lehman, Constance D.

    1998-07-01

    A new prototype imaging system based on ultrasound transmission through the object of interest -- acoustical holography -- was developed which incorporates significant improvements in acoustical and optical design. This system is being evaluated for potential clinical application in the musculoskeletal system, interventional radiology, pediatrics, monitoring of tumor ablation, vascular imaging and breast imaging. System limiting resolution was estimated using a line-pair target with decreasing line thickness and equal separation. For a swept frequency beam from 2.6 - 3.0 MHz, the minimum resolution was 0.5 lp/mm. Apatite crystals were suspended in castor oil to approximate breast microcalcifications. Crystals from 0.425 - 1.18 mm in diameter were well resolved in the acoustic zoom mode. Needle visibility was examined with both a 14-gauge biopsy needle and a 0.6 mm needle. The needle tip was clearly visible throughout the dynamic imaging sequence as it was slowly inserted into a RMI tissue-equivalent breast biopsy phantom. A selection of human images was acquired in several volunteers: a 25 year-old female volunteer with normal breast tissue, a lateral view of the elbow joint showing muscle fascia and tendon insertions, and the superficial vessels in the forearm. Real-time video images of these studies will be presented. In all of these studies, conventional sonography was used for comparison. These preliminary investigations with the new prototype acoustical holography system showed favorable results in comparison to state-of-the-art pulse-echo ultrasound and demonstrate it to be suitable for further clinical study. The new patient interfaces will facilitate orthopedic soft tissue evaluation, study of superficial vascular structures and potentially breast imaging.

  12. Enhanced nearfield acoustic holography for larger distances of reconstructions using fixed parameter Tikhonov regularization

    DOE PAGES

    Chelliah, Kanthasamy; Raman, Ganesh G.; Muehleisen, Ralph T.

    2016-07-07

    This paper evaluates the performance of various regularization parameter choice methods applied to different approaches of nearfield acoustic holography when a very nearfield measurement is not possible. For a fixed grid resolution, the larger the hologram distance, the larger the error in the naive nearfield acoustic holography reconstructions. These errors can be smoothed out by using an appropriate order of regularization. In conclusion, this study shows that by using a fixed/manual choice of regularization parameter, instead of automated parameter choice methods, reasonably accurate reconstructions can be obtained even when the hologram distance is 16 times larger than the grid resolution.

  13. Digital holography-based steganography.

    PubMed

    Hamam, Habib

    2010-12-15

    A steganographic method offering a high hiding capacity is presented in which the techniques of digital holography are used to distribute information from a small secret image across the larger pixel field of a cover image. An iterative algorithm is used to design a phase-only or complex hologram from a padded version of the secret image, quantizing this data according to the carrier data bits that are available within the intended cover image. By introducing the hologram data only into low-order bits of larger amplitude cover pixels, the change in the cover image remains imperceptible to the casual observer, with a peak signal-to-noise ratio of >40 dB.

  14. Subaperture stitching interferometry based on digital holography

    NASA Astrophysics Data System (ADS)

    Pan, Feng; Lu, Xiaoyun; Dong, Bin; Ma, Xichao; Xiao, Wen

    2016-11-01

    A novel subaperture stitching interferometry based on digital holography is developed to measure the deformation of spherical surfaces. The subaperture measurement is performed by off-axis digital holography on single exposure. Then, the subaperture phase maps are obtained by digital holographic reconstruction, in which the phase aberration caused by position errors of each subaperture measurement is effectively compensated by the method of numerical parametric lens. After that, the full aperture phase map is retrieved by a subaperture stitching algorithm, in which the relative alignment errors of adjacent subapertures are eliminated with an iterative process of stitching optimization. The experiments demonstrate the feasibility and effectiveness of the proposed interferometry, which provides a rapid and robust way to measure spherical surfaces with high resolution and precision. A practical example is given to demonstrate the performance of this method. The stitching result shows good agreement with the full-aperture result.

  15. Tomographic reconstruction of transient acoustic fields recorded by pulsed TV holography.

    PubMed

    Gren, P; Schedin, S; Li, X

    1998-02-10

    Pulsed TV holography combined with computerized tomography (CT) are used to evaluate the three-dimensional distribution of transient acoustic fields in air. Experiments are performed with an electrical discharge between two electrodes as the sound source. Holograms from several directions of the acoustic field are recorded directly onto a CCD detector by use of a double-pulsed ruby laser as the light source. Phase maps, representing projections of the acoustic field, are evaluated quantitatively from the recorded holograms. The projections are used for the CT reconstruction to evaluate the pressure-field distribution in any cross section of the measured volume of air.

  16. Leakage detection and quantification techniques using various methods of nearfield acoustic holography

    NASA Astrophysics Data System (ADS)

    Chelliah, Kanthasamy

    This thesis proposes an acoustic technique to detect and relatively quantify leakages in buildings and enclosures using various methods of nearfield acoustic holography (NAH). This laboratory study was performed on a scaled, wooden building model. Known leakages can be created in the wooden model and the acoustic method was tested to localize and relatively quantify these known leakage areas. An acoustic source was placed inside the building model and a planar hologram measurement was performed near the surface of the building model. Various methods of NAH were applied on the hologram data to reconstruct the sound pressure field on the wall of the building model. The detection and quantification capabilities of four different NAH methods, namely, discrete Fourier transform (DFT) based NAH, equivalent source model (ESM) based NAH, boundary element method (BEM) based NAH and statistically optimized NAH (SONAH), were compared in this study. It was shown that the NAH methods were able to successfully locate and relatively quantify the area of the leakages using the reconstructions. Although all the four algorithms produced comparable results in the very nearfield, at larger hologram distances, ESM and SONAH reconstructions were more accurate than the reconstructions using the other methods. Although, ESM and SONAH produced similar results for most of the cases, ESM is more preferable due to its simplicity in implementation and less computational time requirements. Lower frequency reconstructions were found to be more accurate and advantageous in the context of leakage detection and quantification. When the hologram distance was increased more than a particular limit, all the four algorithms arrive at inaccurate reconstructions due to the very ill-conditioned propagation matrices. New filtering methods to alleviate these larger reconstruction errors were introduced and the results were demonstrated. Effects of large sensor phase mismatch were also studied. It was

  17. Polarization manipulation in single refractive prism based holography lithography

    NASA Astrophysics Data System (ADS)

    Xiong, Wenjie; Xu, Yi; Xiao, Yujian; Lv, Xiaoxu; Wu, Lijun

    2015-01-01

    We propose theoretically and demonstrate experimentally a simple but effective strategy for polarization manipulation in single refractive prism based holographic lithography. By tuning the polarization of a single laser beam, we can obtain the pill shape interference pattern with a high-contrast where a complex optical setup and multiple polarizers are needed in the conventional holography lithography. Fabrication of pill shape two-dimensional polymer photonic crystals using one beam and one shoot holography lithography is shown as an example to support our theoretical results. This integrated polarization manipulation technique can release the crucial stability restrictions imposed on the multiple beams holography lithography.

  18. Near-field acoustic holography using sparse regularization and compressive sampling principles.

    PubMed

    Chardon, Gilles; Daudet, Laurent; Peillot, Antoine; Ollivier, François; Bertin, Nancy; Gribonval, Rémi

    2012-09-01

    Regularization of the inverse problem is a complex issue when using near-field acoustic holography (NAH) techniques to identify the vibrating sources. This paper shows that, for convex homogeneous plates with arbitrary boundary conditions, alternative regularization schemes can be developed based on the sparsity of the normal velocity of the plate in a well-designed basis, i.e., the possibility to approximate it as a weighted sum of few elementary basis functions. In particular, these techniques can handle discontinuities of the velocity field at the boundaries, which can be problematic with standard techniques. This comes at the cost of a higher computational complexity to solve the associated optimization problem, though it remains easily tractable with out-of-the-box software. Furthermore, this sparsity framework allows us to take advantage of the concept of compressive sampling; under some conditions on the sampling process (here, the design of a random array, which can be numerically and experimentally validated), it is possible to reconstruct the sparse signals with significantly less measurements (i.e., microphones) than classically required. After introducing the different concepts, this paper presents numerical and experimental results of NAH with two plate geometries, and compares the advantages and limitations of these sparsity-based techniques over standard Tikhonov regularization.

  19. Military jet noise source imaging using multisource statistically optimized near-field acoustical holography.

    PubMed

    Wall, Alan T; Gee, Kent L; Neilsen, Tracianne B; McKinley, Richard L; James, Michael M

    2016-04-01

    The identification of acoustic sources is critical to targeted noise reduction efforts for jets on high-performance tactical aircraft. This paper describes the imaging of acoustic sources from a tactical jet using near-field acoustical holography techniques. The measurement consists of a series of scans over the hologram with a dense microphone array. Partial field decomposition methods are performed to generate coherent holograms. Numerical extrapolation of data beyond the measurement aperture mitigates artifacts near the aperture edges. A multisource equivalent wave model is used that includes the effects of the ground reflection on the measurement. Multisource statistically optimized near-field acoustical holography (M-SONAH) is used to reconstruct apparent source distributions between 20 and 1250 Hz at four engine powers. It is shown that M-SONAH produces accurate field reconstructions for both inward and outward propagation in the region spanned by the physical hologram measurement. Reconstructions across the set of engine powers and frequencies suggests that directivity depends mainly on estimated source location; sources farther downstream radiate at a higher angle relative to the inlet axis. At some frequencies and engine powers, reconstructed fields exhibit multiple radiation lobes originating from overlapped source regions, which is a phenomenon relatively recently reported for full-scale jets.

  20. Novel Acoustic Scattering Processes for Target Discrimination

    DTIC Science & Technology

    2006-09-30

    based on acoustic holography algorithms): It has been possible to form images from data acquired as noted in item (2) by the application of a back...propagation algorithm based on the methods of acoustic holography . Selected results relevant to the interpretation of Bistatic SAS images are noted...to back-propagate the sampled acoustic signal using algorithms originally developed for high-frequency acoustical holography [10]. Data is only

  1. Synthetic holography based on scanning microcavity

    NASA Astrophysics Data System (ADS)

    Di Donato, A.; Farina, M.

    2015-11-01

    Synthetic optical holography (SOH) is an imaging technique, introduced in scanning microscopy to record amplitude and phase of a scattered field from a sample. In this paper, it is described a novel implementation of SOH through a lens-free low-coherence system, based on a scanning optical microcavity. This technique combines the low-coherence properties of the source with the mutual interference of scattered waves and the resonant behavior of a micro-cavity, in order to realize a high sensitive imaging system. Micro-cavity is compact and realized by approaching a cleaved optical fiber to the sample. The scanning system works in an open-loop configuration without the need for a reference wave, usually required in interferometric systems. Measurements were performed over calibration samples and a lateral resolution of about 1 μm is achieved by means of an optical fiber with a Numerical Aperture (NA) equal to 0.1 and a Mode Field Diameter (MDF) of 5.6 μm.

  2. Novel Acoustic Scattering Processes for Target Discrimination

    DTIC Science & Technology

    2007-09-30

    acoustic signal using algorithms originally developed for high-frequency acoustical holography [11]. Data is only acquired by scanning a hydrophone ...by the application of a back-propagation algorithm based on the methods of acoustic holography . Selected results relevant to the interpretation of...Novel Acoustic Scattering Processes for Target Discrimination Philip L. Marston Physics and Astronomy Dept., Washington State University, Pullman

  3. Investigation of 3D surface acoustic waves in granular media with 3-color digital holography

    NASA Astrophysics Data System (ADS)

    Leclercq, Mathieu; Picart, Pascal; Penelet, Guillaume; Tournat, Vincent

    2017-01-01

    This paper reports the implementation of digital color holography to investigate elastic waves propagating along a layer of a granular medium. The holographic set-up provides simultaneous recording and measurement of the 3D dynamic displacement at the surface. Full-field measurements of the acoustic amplitude and phase at different excitation frequencies are obtained. It is shown that the experimental data can be used to obtain the dispersion curve of the modes propagating in this granular medium layer. The experimental dispersion curve and that obtained from a finite element modeling of the problem are found to be in good agreement. In addition, full-field images of the interaction of an acoustic wave guided in the granular layer with a buried object are also shown.

  4. Developing a confocal acoustic holography microscope for non-invasive 3D temperature and composition measurements.

    PubMed

    Herring, Rodney A; Jacquemin, Peter; Sawicka, Barbara D; Atalick, Stefan

    2009-06-01

    A confocal acoustic holography microscope (CAHM) has been designed, simulated and partially verified experimentally to take holograms for non-invasive, three-dimensional measurements of a specimen's refractive indices from one view point. The designed and simulated prototype CAHM used a frequency of 2.25 MHz and measured sound speed changes of 16 m/s, temperature changes of 5 degrees C and had a spatial resolution of 660 microm. With future improvements utilizing the latest technologies such as two-dimensional array detectors, Micro-Electro-Mechanical Systems (MEMS), and acoustic lenses, resolutions of 1m/s, 0.5 degrees C, and 150 microm are expected. The CAHM is expected to have many useful applications, including non-invasive mass and heat transfer measurements in fluids and materials and as a medical diagnostic tool to non-intrusively visualize compositions and temperatures within the human body.

  5. Near field acoustic holography measurements of carbon nanotube thin film speakers.

    PubMed

    Asgarisabet, Mahsa; Barnard, Andrew R; Bouman, Troy M

    2016-12-01

    Carbon nanotube (CNT) thin film speakers produce sound with the thermoacoustic effect. Better understanding of the physical acoustic properties of these speakers will drive future design improvements. Measuring acoustic properties at the surface of the CNT thin film is difficult because the films, themselves, do not vibrate, are fragile and have a high surface temperature. In order to measure the surface particle velocity and sound pressure level (SPL), near field acoustic holography (NAH) has been used by employing probe microphones. NAH images the acoustic quantities of the source system using the set of acoustic pressure measurements on a hologram parallel to the source surface. It is shown that the particle velocity at the surface of an open-air, double-sided speaker is nominally zero, as expected. However, the SPL distribution is not uniform on the source surface, contrary to common lumped parameter model assumptions. Also, particle velocity and sound intensity distributions on the hologram have been obtained in this study. Finally, measured directivity patterns of the planar CNT speaker are reported.

  6. Compressive Fresnel digital holography using Fresnelet based sparse representation

    NASA Astrophysics Data System (ADS)

    Ramachandran, Prakash; Alex, Zachariah C.; Nelleri, Anith

    2015-04-01

    Compressive sensing (CS) in digital holography requires only very less number of pixel level detections in hologram plane for accurate image reconstruction and this is achieved by exploiting the sparsity of the object wave. When the input object fields are non-sparse in spatial domain, CS demands a suitable sparsification method like wavelet decomposition. The Fresnelet, a suitable wavelet basis for processing Fresnel digital holograms is an efficient sparsifier for the complex Fresnel field obtained by the Fresnel transform of the object field and minimizes the mutual coherence between sensing and sparsifying matrices involved in CS. The paper demonstrates the merits of Fresnelet based sparsification in compressive digital Fresnel holography over conventional method of sparsifying the input object field. The phase shifting digital Fresnel holography (PSDH) is used to retrieve the complex Fresnel field for the chosen problem. The results are presented from a numerical experiment to show the proof of the concept.

  7. Experimental study using Nearfield Acoustical Holography of sound transmission fuselage sidewall structures

    NASA Technical Reports Server (NTRS)

    Maynard, J. D.

    1983-01-01

    This project involves the development of the Nearfield Acoustic Holography (NAH) technique (in particular its extension from single frequency to wideband noise measurement) and its application in a detailed study of the noise radiation characteristics of several samples of aircraft sidewall panels. With the extensive amount of information provided by the NAH technique, the properties of the sound field radiated by the panels may be correlated with their structure, mounting, and excitation (single frequency or wideband, spatially correlated or uncorrelated, structure-borne). The work accomplished at the beginning of this grant period included: (1) Calibration of the 256 microphone array and test of its accuracy. (2) extension of the facility to permit measurements on wideband noise sources. The extensions incuded the addition of high-speed data acquisition hardware and an array processor, and the development of new software. (3) Installation of motion picture graphics for correlating panel motion with structure, mounting, radiation, etc. (4) Development of new holographic data processing techniques.

  8. Regularization method for measurement of structural intensity using nearfield acoustical holography.

    PubMed

    Saijyou, Kenji; Okawara, Chiaki

    2005-04-01

    The regularization method for measurement of structural intensity using nearfield acoustical holography is proposed. Spatial derivatives of normal displacement are necessary to obtain the structural intensity. The derivative operations amplify high-wave-number components of measurement noise. Therefore, the estimation of an appropriate wave-number filter is crucial for implementation of the measurement of structural intensity. In conventional methods, this wave-number filter is determined from the flexural wavelength. And the same wave-number filter is applied to obtain all spatial derivatives. As a result, structural intensity obtained from the pressure hologram, whose signal-to-noise ratio is low, is seriously contaminated by the noise. To overcome this difficulty, regularization theory is applied to determine the appropriate wave-number filter for each order of derivatives. The effectiveness of the proposed method is demonstrated by experiments.

  9. Holography: A survey

    NASA Technical Reports Server (NTRS)

    Dudley, D. D.

    1973-01-01

    The development of holography and the state of the art in recording and displaying information, microscopy, motion, pictures, and television applications are discussed. In addition to optical holography, information is presented on microwave, acoustic, ultrasonic, and seismic holography. Other subjects include data processing, data storage, pattern recognition, and computer-generated holography. Diagrams of holographic installations are provided. Photographs of typical holographic applications are used to support the theoretical aspects.

  10. Shape and 3D acoustically induced vibrations of the human eardrum characterized by digital holography

    NASA Astrophysics Data System (ADS)

    Khaleghi, Morteza; Furlong, Cosme; Cheng, Jeffrey Tao; Rosowski, John J.

    2014-07-01

    The eardrum or Tympanic Membrane (TM) transfers acoustic energy from the ear canal (at the external ear) into mechanical motions of the ossicles (at the middle ear). The acousto-mechanical-transformer behavior of the TM is determined by its shape and mechanical properties. For a better understanding of hearing mysteries, full-field-of-view techniques are required to quantify shape, nanometer-scale sound-induced displacement, and mechanical properties of the TM in 3D. In this paper, full-field-of-view, three-dimensional shape and sound-induced displacement of the surface of the TM are obtained by the methods of multiple wavelengths and multiple sensitivity vectors with lensless digital holography. Using our developed digital holographic systems, unique 3D information such as, shape (with micrometer resolution), 3D acoustically-induced displacement (with nanometer resolution), full strain tensor (with nano-strain resolution), 3D phase of motion, and 3D directional cosines of the displacement vectors can be obtained in full-field-ofview with a spatial resolution of about 3 million points on the surface of the TM and a temporal resolution of 15 Hz.

  11. Quantitative measurement of ultrasound pressure field by optical phase contrast method and acoustic holography

    NASA Astrophysics Data System (ADS)

    Oyama, Seiji; Yasuda, Jun; Hanayama, Hiroki; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    A fast and accurate measurement of an ultrasound field with various exposure sequences is necessary to ensure the efficacy and safety of various ultrasound applications in medicine. The most common method used to measure an ultrasound pressure field, that is, hydrophone scanning, requires a long scanning time and potentially disturbs the field. This may limit the efficiency of developing applications of ultrasound. In this study, an optical phase contrast method enabling fast and noninterfering measurements is proposed. In this method, the modulated phase of light caused by the focused ultrasound pressure field is measured. Then, a computed tomography (CT) algorithm used to quantitatively reconstruct a three-dimensional (3D) pressure field is applied. For a high-intensity focused ultrasound field, a new approach that combines the optical phase contrast method and acoustic holography was attempted. First, the optical measurement of focused ultrasound was rapidly performed over the field near a transducer. Second, the nonlinear propagation of the measured ultrasound was simulated. The result of the new approach agreed well with that of the measurement using a hydrophone and was improved from that of the phase contrast method alone with phase unwrapping.

  12. Source characterization of a subsonic jet by using near-field acoustical holography.

    PubMed

    Lee, Moohyung; Bolton, J Stuart

    2007-02-01

    In the present study, patch near-field acoustical holography was used in conjunction with a multireference, cross-spectral sound pressure measurement to visualize the sound field emitted by a subsonic jet and to predict its farfield radiation pattern. A strategy for microphone array design is described that accounts for the low spatial coherence of aeroacoustic sources and for microphone self-noise resulting from entrained flow near the jet. In the experiments, a 0.8-cm-diameter burner was used to produce a subsonic, turbulent jet with a Mach number of 0.26. Six fixed, linear arrays holding eight reference microphones apiece were disposed circumferentially around the jet, and a circular array holding sixteen, equally spaced field microphones was traversed along the jet axis to measure the sound field on a 30-cm-diameter cylindrical surface enclosing the jet. The results revealed that the jet could be modeled as a combination of eleven uncorrelated dipole-, quadrupole-, and octupole-like sources, and the contribution of each source type to the total radiated sound power could be identified. Both the total sound field reconstructed in a three-dimensional space and the farfield radiation directivity obtained by using the latter model were successfully validated by comparisons to directly measured results.

  13. Application of cylindrical near-field acoustical holography to the visualization of aeroacoustic sources.

    PubMed

    Lee, Moohyung; Bolton, J Stuart; Mongeau, Luc

    2003-08-01

    The purpose of this study was to develop methods for visualizing the sound radiation from aeroacoustic sources in order to identify their source strength distribution, radiation patterns, and to quantify the performance of noise control solutions. Here, cylindrical Near-field Acoustical Holography was used for that purpose. In a practical holographic measurement of sources comprising either partially correlated or uncorrelated subsources, it is necessary to use a number of reference microphones so that the sound field on the hologram surface can be decomposed into mutually incoherent partial fields before holographic projection. In this article, procedures are described for determining the number of reference microphones required when visualizing partially correlated aeroacoustic sources; performing source nonstationarity compensation; and applying regularization. The procedures have been demonstrated by application to a ducted fan. Holographic tests were performed to visualize the sound radiation from that source in its original form. The system was then altered to investigate the effect of two modifications on the fan's sound radiation pattern: first, leaks were created in the fan and duct assembly, and second, sound absorbing material was used to line the downstream duct section. Results in all three cases are shown at the blade passing frequency and for a broadband noise component. In the absence of leakage, both components were found to exhibit a dipole-like radiation pattern. Leakage was found to have a strong influence on the directivity of the blade passing tone. The increase of the flow resistance caused by adding the acoustical lining resulted in a nearly symmetric reduction of sound radiation.

  14. Compressive Holography

    NASA Astrophysics Data System (ADS)

    Lim, Se Hoon

    Compressive holography estimates images from incomplete data by using sparsity priors. Compressive holography combines digital holography and compressive sensing. Digital holography consists of computational image estimation from data captured by an electronic focal plane array. Compressive sensing enables accurate data reconstruction by prior knowledge on desired signal. Computational and optical co-design optimally supports compressive holography in the joint computational and optical domain. This dissertation explores two examples of compressive holography: estimation of 3D tomographic images from 2D data and estimation of images from under sampled apertures. Compressive holography achieves single shot holographic tomography using decompressive inference. In general, 3D image reconstruction suffers from underdetermined measurements with a 2D detector. Specifically, single shot holographic tomography shows the uniqueness problem in the axial direction because the inversion is ill-posed. Compressive sensing alleviates the ill-posed problem by enforcing some sparsity constraints. Holographic tomography is applied for video-rate microscopic imaging and diffuse object imaging. In diffuse object imaging, sparsity priors are not valid in coherent image basis due to speckle. So incoherent image estimation is designed to hold the sparsity in incoherent image basis by support of multiple speckle realizations. High pixel count holography achieves high resolution and wide field-of-view imaging. Coherent aperture synthesis can be one method to increase the aperture size of a detector. Scanning-based synthetic aperture confronts a multivariable global optimization problem due to time-space measurement errors. A hierarchical estimation strategy divides the global problem into multiple local problems with support of computational and optical co-design. Compressive sparse aperture holography can be another method. Compressive sparse sampling collects most of significant field

  15. Femtosecond digital holography based on spatial light modulator

    NASA Astrophysics Data System (ADS)

    Lu, Xiaowei; Li, Jingzhen; Chen, Hongyi

    2013-12-01

    A high-speed digital holography based on a liquid crystal Spatial Light Modulator (LC-SLM) is presented. The production of multi-beam and control of their delay time can be achieved by controllable wavefront coding theory. In this paper, a Dammann phase grating was designed using a SLM to product multi-beam for extremely high speed digital holographic imaging. The required beam deflection could be obtained by adjusting programmable phase mask for controlling the spatial diffraction of input beam. The framing time is decided by interval beam angles and the distances between input plane and record plane. Theoretical derivate of generation multi beams based on SLM was proposed, and phase recover software was also made.

  16. High resolution digital holography based on the point source scanning

    NASA Astrophysics Data System (ADS)

    Wang, Minchao; Wang, Dayong; Rong, Lu; Wang, Yunxin; Wang, Fengpeng; Lin, Qiaowen

    2016-10-01

    Digital holographic microscopy has been widely used for the imaging of micro-objects and biological samples. Lensless in-line digital holographic microscopy is capable of wide field-of-view imaging. However the spatial resolution of the reconstructed images is limited by the pixel size of the detector. The relative position shift between the sample and the detector can effectively improve the resolution in the traditional sub-pixel shifting method, but it requires a high precision of translation stage. To overcome this problem, we propose a method based on the point source scanning to realize sub-pixel shifting. High precision sub-pixel shifting is achieved easily by using the geometric between point source and detector. Through moving the point source, multiple holograms with sub-pixel shifts are captured. These holograms are merged together to obtained a high resolution hologram by a synthesizing algorithm. Then, the high resolution reconstructed image of the object can be obtained by the angular spectrum algorithm. The feasibility of the proposed method is demonstrated by simulation and experiments. A USAF resolution test target was used as the object. Compared with the traditional digital holography, a higher resolution reconstructed image is obtained by our method. The proposed method has the advantages of simple recording setup and lower precision requirement of the translation stage. It can achieve the wide field-of-view and high resolution imaging.

  17. Digital reflection holography based systems development for MEMS testing

    NASA Astrophysics Data System (ADS)

    Singh, Vijay Raj; Liansheng, Sui; Asundi, Anand

    2010-05-01

    MEMS are tiny mechanical devices that are built onto semiconductor chips and are measured in micrometers and nanometers. Testing of MEMS device is an important part in carrying out their functional assessment and reliability analysis. Development of systems based on digital holography (DH) for MEMS inspection and characterization is presented in this paper. Two DH reflection systems, table-top and handheld types, are developed depending on the MEMS measurement requirements and their capabilities are presented. The methodologies for the systems are developed for 3D profile inspection and static & dynamic measurements, which is further integrated with in-house developed software that provides the measurement results in near real time. The applications of the developed systems are demonstrated for different MEMS devices for 3D profile inspection, static deformation/deflection measurements and vibration analysis. The developed systems are well suitable for the testing of MEMS and Microsystems samples, with full-field, static & dynamic inspection as well as to monitor micro-fabrication process.

  18. Dynamic imaging through turbid media based on digital holography.

    PubMed

    Li, Shiping; Zhong, Jingang

    2014-03-01

    Imaging through turbid media using visible or IR light instead of harmful x ray is still a challenging problem, especially in dynamic imaging. A method of dynamic imaging through turbid media using digital holography is presented. In order to match the coherence length between the dynamic object wave and the reference wave, a cw laser is used. To solve the problem of difficult focusing in imaging through turbid media, an autofocus technology is applied. To further enhance the image contrast, a spatial filtering technique is used. A description of digital holography and experiments of imaging the objects hidden in turbid media are presented. The experimental result shows that dynamic images of the objects can be achieved by the use of digital holography.

  19. Partial sound field decomposition in multireference near-field acoustical holography by using optimally located virtual references

    NASA Astrophysics Data System (ADS)

    Kim, Yong-Joe; Bolton, J. Stuart; Kwon, Hyu-Sang

    2004-04-01

    It has been shown previously that the multiple reference and field signals recorded during a scanning acoustical holography measurement can be used to decompose the sound field radiated by a composite sound source into mutually incoherent partial fields. To obtain physically meaningful partial fields, i.e., fields closely related to particular component sources, the reference microphones should be positioned as close as possible to the component physical sources that together comprise the complete source. However, it is not always possible either to identify the optimal reference microphone locations prior to performing a holographic measurement, or to place reference microphones at those optimal locations, even if known, owing to physical constraints. Here, post-processing procedures are described that make it possible both to identify the optimal reference microphone locations and to place virtual references at those locations after performing a holographic measurement. The optimal reference microphone locations are defined to be those at which the MUSIC power is maximized in a three-dimensional space reconstructed by holographic projection. The acoustic pressure signals at the locations thus identified can then be used as optimal ``virtual'' reference signals. It is shown through an experiment and numerical simulation that the optimal virtual reference signals can be successfully used to identify physically meaningful partial sound fields, particularly when used in conjunction with partial coherence decomposition procedures.

  20. Recent progress on fully analytic mesh based computer-generated holography

    NASA Astrophysics Data System (ADS)

    Park, Jae-Hyeung

    2016-10-01

    Computer generated holography plays a main role in the contents generation for holographic displays and digital archiving of three-dimensional objects. The fully analytic mesh based computer generated holography finds exact complex optical field for each triangular mesh of the three-dimensional objects for given sampling interval in the hologram plane without any approximation, enhancing the quality of the reconstruction. The mesh based processing rather than conventional point based one makes it compatible with most computer graphics techniques and efficient especially for large objects. In this paper, we present a few recent progress on fully analytic mesh based computer generated holography techniques including the dark line artifact removal, continuous shading of each mesh surface, the implementation of the angular reflectance distribution of the object surface and application of the texture map.

  1. Applications of holography. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Carrigan, B.

    1980-05-01

    The bibliography covers studies on the applications of holography in such areas as photograping high-speed particles, nondestructive testing of material defects, strain analysis, microscopy, interferometry, vibration measurement, and medical diagnosis. This updated bibliography contains 249 abstracts, none of which are new entries to the previous edition.

  2. Applications of holography. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Carrigan, B.

    1980-05-01

    The bibliography covers studies on the applications of holography in such areas as photographing high-speed particles, nondestructive testing of material defects, strain analysis, microscopy, interferometry, vibration measurement, and medical diagnosis. This updated bibliography contains 59 abstracts, 42 of which are new entries to the previous edition.

  3. Reconstruction and separation of vibratory field using structural holography

    NASA Astrophysics Data System (ADS)

    Chesnais, C.; Totaro, N.; Thomas, J.-H.; Guyader, J.-L.

    2017-02-01

    A method for reconstructing and separating vibratory field on a plate-like structure is presented. The method, called ;Structural Holography; is derived from classical Near-field Acoustic Holography (NAH) but in the vibratory domain. In this case, the plate displacement is measured on one-dimensional lines (the holograms) and used to reconstruct the entire two-dimensional displacement field. As a consequence, remote measurements on non directly accessible zones are possible with Structural Holography. Moreover, as it is based on the decomposition of the field into forth and back waves, Structural Holography permits to separate forces in the case of multi-sources excitation. The theoretical background of the Structural Holography method is described first. Then, to illustrate the process and the possibilities of Structural Holography, the academic test case of an infinite plate excited by few point forces is presented. With the principle of vibratory field separation, the displacement fields produced by each point force separately is reconstructed. However, the displacement field is not always meaningful and some additional treatments are mandatory to localize the position of point forces for example. From the simple example of an infinite plate, a post-processing based on the reconstruction of the structural intensity field is thus proposed. Finally, Structural Holography is generalized to finite plates and applied to real experimental measurements

  4. Image authentication via sparsity-based phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Chen, Wen; Chen, Xudong

    2015-03-01

    Digital holography has been widely studied in recent years, and a number of applications have been demonstrated. In this paper, we demonstrate that sparsity-based phase-shifting digital holography can be applied for image authentication. In phase-shifting digital holography, the holograms are sequentially recorded. Only small parts of each hologram are available for numerical reconstruction. It is found that nonlinear correlation algorithm can be applied to simply authenticate the reconstructed object. The results illustrate that the recovered image can be correctly verified. In the developed system, the recorded holograms are highly compressed which can facilitate data storage or transmission, and one simple authentication strategy has been established instead of applying relatively complex algorithms (such as compressive sensing) to recover the object.

  5. Acoustic Holographic Rendering with Two-dimensional Metamaterial-based Passive Phased Array.

    PubMed

    Xie, Yangbo; Shen, Chen; Wang, Wenqi; Li, Junfei; Suo, Dingjie; Popa, Bogdan-Ioan; Jing, Yun; Cummer, Steven A

    2016-10-14

    Acoustic holographic rendering in complete analogy with optical holography are useful for various applications, ranging from multi-focal lensing, multiplexed sensing and synthesizing three-dimensional complex sound fields. Conventional approaches rely on a large number of active transducers and phase shifting circuits. In this paper we show that by using passive metamaterials as subwavelength pixels, holographic rendering can be achieved without cumbersome circuitry and with only a single transducer, thus significantly reducing system complexity. Such metamaterial-based holograms can serve as versatile platforms for various advanced acoustic wave manipulation and signal modulation, leading to new possibilities in acoustic sensing, energy deposition and medical diagnostic imaging.

  6. Acoustic Holographic Rendering with Two-dimensional Metamaterial-based Passive Phased Array

    NASA Astrophysics Data System (ADS)

    Xie, Yangbo; Shen, Chen; Wang, Wenqi; Li, Junfei; Suo, Dingjie; Popa, Bogdan-Ioan; Jing, Yun; Cummer, Steven A.

    2016-10-01

    Acoustic holographic rendering in complete analogy with optical holography are useful for various applications, ranging from multi-focal lensing, multiplexed sensing and synthesizing three-dimensional complex sound fields. Conventional approaches rely on a large number of active transducers and phase shifting circuits. In this paper we show that by using passive metamaterials as subwavelength pixels, holographic rendering can be achieved without cumbersome circuitry and with only a single transducer, thus significantly reducing system complexity. Such metamaterial-based holograms can serve as versatile platforms for various advanced acoustic wave manipulation and signal modulation, leading to new possibilities in acoustic sensing, energy deposition and medical diagnostic imaging.

  7. Acoustic Holographic Rendering with Two-dimensional Metamaterial-based Passive Phased Array

    PubMed Central

    Xie, Yangbo; Shen, Chen; Wang, Wenqi; Li, Junfei; Suo, Dingjie; Popa, Bogdan-Ioan; Jing, Yun; Cummer, Steven A.

    2016-01-01

    Acoustic holographic rendering in complete analogy with optical holography are useful for various applications, ranging from multi-focal lensing, multiplexed sensing and synthesizing three-dimensional complex sound fields. Conventional approaches rely on a large number of active transducers and phase shifting circuits. In this paper we show that by using passive metamaterials as subwavelength pixels, holographic rendering can be achieved without cumbersome circuitry and with only a single transducer, thus significantly reducing system complexity. Such metamaterial-based holograms can serve as versatile platforms for various advanced acoustic wave manipulation and signal modulation, leading to new possibilities in acoustic sensing, energy deposition and medical diagnostic imaging. PMID:27739472

  8. Twin image removal in digital in-line holography based on iterative inter-projections

    NASA Astrophysics Data System (ADS)

    Chen, Bing Kuan; Chen, Tai-Yu; Hung, Shau Gang; Huang, Sheng-Lung; Lin, Jiunn-Yuan

    2016-06-01

    A simple and efficient phase retrieval method based on the iterative inter-projections of the recorded Fourier modulus between two effective holographic planes is developed to eliminate the twin image in digital in-line holography. The proposed algorithm converges stably in phase extraction procedures without requiring any prior knowledge or sophisticated support of the object and is applicable to lensless Gabor and Fourier holography as well as holographic microscopy with imaging lenses. Numerical and experimental results suggest that the spatial resolution enhancement on the reconstructed image can be achieved with this technique due to the capability of recovering the diffraction phases of low-intensity signals.

  9. Violin f-hole contribution to far-field radiation via patch near-field acoustical holography.

    PubMed

    Bissinger, George; Williams, Earl G; Valdivia, Nicolas

    2007-06-01

    The violin radiates either from dual ports (f-holes) or via surface motion of the corpus (top+ribs+back), with no clear delineation between these sources. Combining "patch" near-field acoustical holography over just the f-hole region of a violin with far-field radiativity measurements over a sphere, it was possible to separate f-hole from surface motion contributions to the total radiation of the corpus below 2.6 kHz. A0, the Helmholtz-like lowest cavity resonance, radiated essentially entirely through the f-holes as expected while A1, the first longitudinal cavity mode with a node at the f-holes, had no significant f-hole radiation. The observed A1 radiation comes from an indirect radiation mechanism, induced corpus motion approximately mirroring the cavity pressure profile seen for violinlike bowed string instruments across a wide range of sizes. The first estimates of the fraction of radiation from the f-holes F(f) indicate that some low frequency corpus modes thought to radiate only via surface motion (notably the first corpus bending modes) had significant radiation through the f-holes, in agreement with net volume changes estimated from experimental modal analysis. F(f) generally trended lower with increasing frequency, following corpus mobility decreases. The f-hole directivity (top/back radiativity ratio) was generally higher than whole-violin directivity.

  10. Characterization of a multi-element clinical HIFU system using acoustic holography and nonlinear modeling.

    PubMed

    Kreider, Wayne; Yuldashev, Petr V; Sapozhnikov, Oleg A; Farr, Navid; Partanen, Ari; Bailey, Michael R; Khokhlova, Vera A

    2013-08-01

    High-intensity focused ultrasound (HIFU) is a treatment modality that relies on the delivery of acoustic energy to remote tissue sites to induce thermal and/or mechanical tissue ablation. To ensure the safety and efficacy of this medical technology, standard approaches are needed for accurately characterizing the acoustic pressures generated by clinical ultrasound sources under operating conditions. Characterization of HIFU fields is complicated by nonlinear wave propagation and the complexity of phased-array transducers. Previous work has described aspects of an approach that combines measurements and modeling, and here we demonstrate this approach for a clinical phased-array transducer. First, low amplitude hydrophone measurements were performed in water over a scan plane between the array and the focus. Second, these measurements were used to holographically reconstruct the surface vibrations of the transducer and to set a boundary condition for a 3-D acoustic propagation model. Finally, nonlinear simulations of the acoustic field were carried out over a range of source power levels. Simulation results were compared with pressure waveforms measured directly by hydrophone at both low and high power levels, demonstrating that details of the acoustic field, including shock formation, are quantitatively predicted.

  11. Characterization of a Multi-element Clinical HIFU System Using Acoustic Holography and Nonlinear Modeling

    PubMed Central

    Kreider, Wayne; Yuldashev, Petr V.; Sapozhnikov, Oleg A.; Farr, Navid; Partanen, Ari; Bailey, Michael R.; Khokhlova, Vera A.

    2014-01-01

    High-intensity focused ultrasound (HIFU) is a treatment modality that relies on the delivery of acoustic energy to remote tissue sites to induce thermal and/or mechanical tissue ablation. To ensure the safety and efficacy of this medical technology, standard approaches are needed for accurately characterizing the acoustic pressures generated by clinical ultrasound sources under operating conditions. Characterization of HIFU fields is complicated by nonlinear wave propagation and the complexity of phased-array transducers. Previous work has described aspects of an approach that combines measurements and modeling, and here we demonstrate this approach for a clinical phased array transducer. First, low-amplitude hydrophone measurements were performed in water over a scan plane between the array and the focus. Second, these measurements were used to holographically reconstruct the surface vibrations of the transducer and to set a boundary condition for a 3-D acoustic propagation model. Finally, nonlinear simulations of the acoustic field were carried out over a range of source power levels. Simulation results were compared to pressure waveforms measured directly by hydrophone at both low and high power levels, demonstrating that details of the acoustic field including shock formation are quantitatively predicted. PMID:25004539

  12. Predictive dynamic digital holography

    NASA Astrophysics Data System (ADS)

    Sulaiman, Sennan; Gibson, Steve; Spencer, Mark

    2016-09-01

    Digital holography has received recent attention for many imaging and sensing applications, including imaging through turbulent and turbid media, adaptive optics, three dimensional projective display technology and optical tweezing. A significant obstacle for digital holography in real-time applications, such as wavefront sensing for high energy laser systems and high speed imaging for target tracking, is the fact that digital holography is computationally intensive; it requires iterative virtual wavefront propagation and hill-climbing to optimize some sharpness criteria. This paper demonstrates real-time methods for digital holography based on approaches developed recently at UCLA for optimal and adaptive identification, prediction, and control of optical wavefronts. The methods presented integrate minimum variance wavefront prediction into digital holography schemes to short-circuit the computationally intensive algorithms for iterative propagation of virtual wavefronts and hill climbing for sharpness optimization.

  13. Cell imaging techniques based on digital image plane holography

    NASA Astrophysics Data System (ADS)

    Chen, Zhaoji; Gong, Wendi; Liu, Feifei; Wang, Huaying

    2010-11-01

    This paper has further studied the implementation methods and recording conditions of digital microscopic image plane holography (DMIPH). Two optical systems of DMIPH were built: one is recording hologram by using plane waves as reference light, the other is recording hologram by spherical reference light. Breast cancer cells and USAF resolution test target is used as tested samples in the experiment. Then the intensity distribution and three-dimensional shape information of the cells are got accurately. The experiment results show that DMIPH avoids the process of finding recording distance by using auto-focusing approach. The recording and reconstruction process of DMIPH is simple. Therefore DMIPH can be applied to the microscopic imaging of cells more effectively.

  14. CINCH (confocal incoherent correlation holography) super resolution fluorescence microscopy based upon FINCH (Fresnel incoherent correlation holography)

    PubMed Central

    Siegel, Nisan; Storrie, Brian; Bruce, Marc

    2016-01-01

    FINCH holographic fluorescence microscopy creates high resolution super-resolved images with enhanced depth of focus. The simple addition of a real-time Nipkow disk confocal image scanner in a conjugate plane of this incoherent holographic system is shown to reduce the depth of focus, and the combination of both techniques provides a simple way to enhance the axial resolution of FINCH in a combined method called “CINCH”. An important feature of the combined system allows for the simultaneous real-time image capture of widefield and holographic images or confocal and confocal holographic images for ready comparison of each method on the exact same field of view. Additional GPU based complex deconvolution processing of the images further enhances resolution. PMID:26839443

  15. Fully Integrated, Multiport, Planar-Waveguide, Spectral Comparators and Multiplexers Based on Lithographic Holography

    DTIC Science & Technology

    2005-08-31

    2005, San Jose, California, USA. 2. C. M. Greiner, T. W. Mossberg, D. Iazikov, "Planar lithographic holography as enabler of integrated photonics (Invited...line set displacement," in Integrated Photonics Research and Applications/Nanophotonicsfor Information Systems Topical Meetings on CD-ROM (The...Based on Holographic Bragg Reflectors," in Integrated Photonics 16 Research and Applications/Nanophotonics for Information Systems Topical Meetings on

  16. 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.

  17. 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.

  18. Field-portable reflection and transmission microscopy based on lensless holography.

    PubMed

    Lee, Myungjun; Yaglidere, Oguzhan; Ozcan, Aydogan

    2011-09-01

    We demonstrate a lensfree dual-mode holographic microscope that can image specimens in both transmission and reflection geometries using in-line transmission and off-axis reflection holography, respectively. This field-portable dual-mode holographic microscope has a weight of ~200 g with dimensions of 15 x 5.5 x 5cm, where a laser source is powered by two batteries. Based on digital in-line holography, our transmission microscope achieves a sub-pixel lateral resolution of ≤2 µm over a wide field-of-view (FOV) of ~24 mm(2) due to its unit fringe magnification geometry. Despite its simplicity and ease of operation, in-line transmission geometry is not suitable to image dense or connected objects such as tissue slides since the reference beam gets distorted causing severe aberrations in reconstruction of such objects. To mitigate this challenge, on the same cost-effective and field-portable assembly we built a lensless reflection mode microscope based on digital off-axis holography where a beam-splitter is used to interfere a tilted reference wave with the reflected light from the object surface, creating an off-axis hologram of the specimens on a CMOS sensor-chip. As a result of the reduced space-bandwidth product of the off-axis geometry compared to its in-line counterpart, the imaging FOV of our reflection mode is reduced to ~9 mm(2), while still achieving a similar sub-pixel resolution of ≤2 µm. We tested the performance of this compact dual-mode microscopy unit by imaging a US-air force resolution test target, various micro-particles as well as a histopathology slide corresponding to skin tissue. Due to its compact, cost-effective, and lightweight design, this dual-mode lensless holographic microscope might especially be useful for field-use or for conducting microscopic analysis in resource-poor settings.

  19. Artistic Representation with Pulsed Holography

    NASA Astrophysics Data System (ADS)

    Ishii, S.

    2013-02-01

    This thesis describes artistic representation through pulsed holography. One of the prevalent practical problems in making holograms is object movement. Any movement of the object or film, including movement caused by acoustic vibration, has the same fatal results. One way of reducing the chance of movement is by ensuring that the exposure is very quick; using a pulsed laser can fulfill this objective. The attractiveness of using pulsed laser is based on the variety of materials or objects that can be recorded (e.g., liquid material or instantaneous scene of a moving object). One of the most interesting points about pulsed holograms is that some reconstructed images present us with completely different views of the real world. For example, the holographic image of liquid material does not appear fluid; it looks like a piece of hard glass that would produce a sharp sound upon tapping. In everyday life, we are unfamiliar with such an instantaneous scene. On the other hand, soft-textured materials such as a feather or wool differ from liquids when observed through holography. Using a pulsed hologram, we can sense the soft touch of the object or material with the help of realistic three-dimensional (3-D) images. The images allow us to realize the sense of touch in a way that resembles touching real objects. I had the opportunity to use a pulsed ruby laser soon after I started to work in the field of holography in 1979. Since then, I have made pulsed holograms of activities, including pouring water, breaking eggs, blowing soap bubbles, and scattering feathers and popcorn. I have also created holographic art with materials and objects, such as silk fiber, fabric, balloons, glass, flowers, and even the human body. Whenever I create art, I like to present the spectator with a new experience in perception. Therefore, I would like to introduce my experimental artwork through those pulsed holograms.

  20. Stochastic dual-plane on-axis digital holography based on Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Wang, Fengpeng; Wang, Dayong; Rong, Lu; Wang, Yunxin; Zhao, Jie

    2016-09-01

    For traditional dual-plane on-axis digital holography, the robustness is lower because it is difficult to maintain the stability of the phase difference between the object beam and the reference beam, and it may be invalid when the objects are on the surface of a medium with uneven thickness. An improved dual-plane digital holographic method based on Mach-Zehnder interferometer is presented to address these problems. Two holograms are recorded at two different planes separated by a small distance. Then, the zero-order image and conjugated image are eliminated by Fourier domain processing. In order to enhance the robustness of the system, the object is illuminated by a stochastic beam that is a speckle wave produced by a diffuser. Simulated and experimental results are shown to demonstrate that the proposed method has greater robustness than the traditional dual-plane on-axis digital holography and it can be used to imaging on the irregular surface of a transparent medium.

  1. Optical scanning holography based on compressive sensing using a digital micro-mirror device

    NASA Astrophysics Data System (ADS)

    A-qian, Sun; Ding-fu, Zhou; Sheng, Yuan; You-jun, Hu; Peng, Zhang; Jian-ming, Yue; xin, Zhou

    2017-02-01

    Optical scanning holography (OSH) is a distinct digital holography technique, which uses a single two-dimensional (2D) scanning process to record the hologram of a three-dimensional (3D) object. Usually, these 2D scanning processes are in the form of mechanical scanning, and the quality of recorded hologram may be affected due to the limitation of mechanical scanning accuracy and unavoidable vibration of stepper motor's start-stop. In this paper, we propose a new framework, which replaces the 2D mechanical scanning mirrors with a Digital Micro-mirror Device (DMD) to modulate the scanning light field, and we call it OSH based on Compressive Sensing (CS) using a digital micro-mirror device (CS-OSH). CS-OSH can reconstruct the hologram of an object through the use of compressive sensing theory, and then restore the image of object itself. Numerical simulation results confirm this new type OSH can get a reconstructed image with favorable visual quality even under the condition of a low sample rate.

  2. Content-based fused off-axis object illumination direct-to-digital holography

    DOEpatents

    Price, Jeffery R.

    2006-05-02

    Systems and methods are described for content-based fused off-axis illumination direct-to-digital holography. A method includes calculating an illumination angle with respect to an optical axis defined by a focusing lens as a function of data representing a Fourier analyzed spatially heterodyne hologram; reflecting a reference beam from a reference mirror at a non-normal angle; reflecting an object beam from an object the object beam incident upon the object at the illumination angle; focusing the reference beam and the object beam at a focal plane of a digital recorder to from the content-based off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis; and digitally recording the content based off-axis illuminated spatially heterodyne hologram including spatially heterodyne fringes for Fourier analysis.

  3. Sparsity-Based Pixel Super Resolution for Lens-Free Digital In-line Holography

    PubMed Central

    Song, Jun; Leon Swisher, Christine; Im, Hyungsoon; Jeong, Sangmoo; Pathania, Divya; Iwamoto, Yoshiko; Pivovarov, Misha; Weissleder, Ralph; Lee, Hakho

    2016-01-01

    Lens-free digital in-line holography (LDIH) is a promising technology for portable, wide field-of-view imaging. Its resolution, however, is limited by the inherent pixel size of an imaging device. Here we present a new computational approach to achieve sub-pixel resolution for LDIH. The developed method is a sparsity-based reconstruction with the capability to handle the non-linear nature of LDIH. We systematically characterized the algorithm through simulation and LDIH imaging studies. The method achieved the spatial resolution down to one-third of the pixel size, while requiring only single-frame imaging without any hardware modifications. This new approach can be used as a general framework to enhance the resolution in nonlinear holographic systems. PMID:27098438

  4. Thermodynamic holography

    NASA Astrophysics Data System (ADS)

    Wei, Bo-Bo; Jiang, Zhan-Feng; Liu, Ren-Bao

    2015-10-01

    The holographic principle states that the information about a volume of a system is encoded on the boundary surface of the volume. Holography appears in many branches of physics, such as optics, electromagnetism, many-body physics, quantum gravity, and string theory. Here we show that holography is also an underlying principle in thermodynamics, a most important foundation of physics. The thermodynamics of a system is fully determined by its partition function. We prove that the partition function of a finite but arbitrarily large system is an analytic function on the complex plane of physical parameters, and therefore the partition function in a region on the complex plane is uniquely determined by its values along the boundary. The thermodynamic holography has applications in studying thermodynamics of nano-scale systems (such as molecule engines, nano-generators and macromolecules) and provides a new approach to many-body physics.

  5. Seismic Holography of Solar Activity

    NASA Technical Reports Server (NTRS)

    Lindsey, Charles

    2000-01-01

    The basic goal of the project was to extend holographic seismic imaging techniques developed under a previous NASA contract, and to incorporate phase diagnostics. Phase-sensitive imaging gives us a powerful probe of local thermal and Doppler perturbations in active region subphotospheres, allowing us to map thermal structure and flows associated with "acoustic moats" and "acoustic glories". These remarkable features were discovered during our work, by applying simple acoustic power holography to active regions. Included in the original project statement was an effort to obtain the first seismic images of active regions on the Sun's far surface.

  6. A hard-threshold based sparse inverse imaging algorithm for optical scanning holography reconstruction

    NASA Astrophysics Data System (ADS)

    Zhao, Fengjun; Qu, Xiaochao; Zhang, Xing; Poon, Ting-Chung; Kim, Taegeun; Kim, You Seok; Liang, Jimin

    2012-03-01

    The optical imaging takes advantage of coherent optics and has promoted the development of visualization of biological application. Based on the temporal coherence, optical coherence tomography can deliver three-dimensional optical images with superior resolutions, but the axial and lateral scanning is a time-consuming process. Optical scanning holography (OSH) is a spatial coherence technique which integrates three-dimensional object into a two-dimensional hologram through a two-dimensional optical scanning raster. The advantages of high lateral resolution and fast image acquisition offer it a great potential application in three-dimensional optical imaging, but the prerequisite is the accurate and practical reconstruction algorithm. Conventional method was first adopted to reconstruct sectional images and obtained fine results, but some drawbacks restricted its practicality. An optimization method based on 2 l norm obtained more accurate results than that of the conventional methods, but the intrinsic smooth of 2 l norm blurs the reconstruction results. In this paper, a hard-threshold based sparse inverse imaging algorithm is proposed to improve the sectional image reconstruction. The proposed method is characterized by hard-threshold based iterating with shrinkage threshold strategy, which only involves lightweight vector operations and matrix-vector multiplication. The performance of the proposed method has been validated by real experiment, which demonstrated great improvement on reconstruction accuracy at appropriate computational cost.

  7. Characterization of Transducer Performance and Narrowband Transient Ultrasonic Fields in Metals by Rayleigh-Sommerfeld Backpropagation of Compression Acoustic Waves Measured with Double-Pulsed Tv Holography

    NASA Astrophysics Data System (ADS)

    Trillo, Cristina; Doval, Ángel F.; Fernández, José L.; Rodríguez-Gómez, Pablo; López-Vázquez, J. Carlos

    2014-10-01

    This article presents a method aimed at the characterization of the narrowband transient acoustic field radiated by an ultrasonic plane transducer into a homogeneous, isotropic and optically opaque prismatic solid, and the assessment of the performance of the acoustic source. The method relies on a previous technique based on the full-field optical measurement of an acoustic wavepacket at the surface of a solid and its subsequent numerical backpropagation within the material. The experimental results show that quantitative transversal and axial profiles of the complex amplitude of the beam can be obtained at any plane between the measurement and excitation surfaces. The reconstruction of the acoustic field at the transducer face, carried out on a defective transducer model, shows that the method could also be suitable for the nondestructive testing of the performance of ultrasonic sources. In all cases, the measurements were performed with the transducer working under realistic loading conditions.

  8. Study of key technology of ghost imaging via compressive sensing for a phase object based on phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Leihong, Zhang; Dong, Liang; Bei, Li; Zilan, Pan; Dawei, Zhang; Xiuhua, Ma

    2015-07-01

    In this article, the algorithm of compressing sensing is used to improve the imaging resolution and realize ghost imaging via compressive sensing for a phase object based on the theoretical analysis of the lensless Fourier imaging of the algorithm of ghost imaging based on phase-shifting digital holography. The algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography uses the bucket detector to measure the total light intensity of the interference and the four-step phase-shifting method is used to obtain the total light intensity of differential interference light. The experimental platform is built based on the software simulation, and the experimental results show that the algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography can obtain the high-resolution phase distribution figure of the phase object. With the same sampling times, the phase clarity of the phase distribution figure obtained by the algorithm of ghost imaging via compressive sensing based on phase-shifting digital holography is higher than that obtained by the algorithm of ghost imaging based on phase-shift digital holography. In this article, this study further extends the application range of ghost imaging and obtains the phase distribution of the phase object.

  9. Dental Holography

    NASA Astrophysics Data System (ADS)

    Dirtoft, Ingegerd

    1983-12-01

    Ten years have passed since the first articles appeared in this new field. The qualities of the laser light together with the need of contactless 3-D measurements for different dental purposes seemed to be extremely promising, but still just a few scientists have used the method and mostly for laboratory studies. For some reason there has been a preponderance for orthodontic measurements. This seems to be a bit peculiar from holographic view compared with measurements for engineering purposes, which usually are made on metals. So naturally holography can become a clinical tool for measurements in the field of fixed bridges, removable partial dentures and implants. One of the problems is that the need for holography in dental research must be fulfilled in collaboration with physicists. Only a two-way communication during an entire experiment can balance both technical and odontological demands and thus give practical and clinical important results. The need for an easy way of handling the evaluation to get all required information is another problem and of course the holographic equipment must be converted to a box easy to handle for everyone. At last the position of dental holography today is going to be carefully examined together with an attempt to look into the hopefully exciting and not to utopic future for this research field.

  10. Acoustically based fetal heart rate monitor

    NASA Technical Reports Server (NTRS)

    Baker, Donald A.; Zuckerwar, Allan J.

    1991-01-01

    The acoustically based fetal heart rate monitor permits an expectant mother to perform the fetal Non-Stress Test in her home. The potential market would include the one million U.S. pregnancies per year requiring this type of prenatal surveillance. The monitor uses polyvinylidene fluoride (PVF2) piezoelectric polymer film for the acoustic sensors, which are mounted in a seven-element array on a cummerbund. Evaluation of the sensor ouput signals utilizes a digital signal processor, which performs a linear prediction routine in real time. Clinical tests reveal that the acoustically based monitor provides Non-Stress Test records which are comparable to those obtained with a commercial ultrasonic transducer.

  11. Multiple-image encryption based on compressive holography using a multiple-beam interferometer

    NASA Astrophysics Data System (ADS)

    Wan, Yuhong; Wu, Fan; Yang, Jinghuan; Man, Tianlong

    2015-05-01

    Multiple-image encryption techniques not only improve the encryption capacity but also facilitate the transmission and storage of the ciphertext. We present a new method of multiple-image encryption based on compressive holography with enhanced data security using a multiple-beam interferometer. By modifying the Mach-Zehnder interferometer, the interference of multiple object beams and unique reference beam is implemented for encrypting multiple images simultaneously into one hologram. The original images modulated with the random phase masks are put in different positions with different distance away from the CCD camera. Each image plays the role of secret key for other images to realize the mutual encryption. Four-step phase shifting technique is combined with the holographic recording. The holographic recording is treated as a compressive sensing process, thus the decryption process is inverted as a minimization problem and the two-step iterative shrinkage/thresholding algorithm (TwIST) is employed to solve this optimization problem. The simulated results about multiple binary and grayscale images encryption are demonstrated to verify the validity and robustness of our proposed method.

  12. Millimeter-Wave Phaseless Antenna Measurement Based on a Modified Off-Axis Holography Setup

    NASA Astrophysics Data System (ADS)

    Arboleya, Ana; Ala-Laurinaho, Juha; Laviada, Jaime; Álvarez, Yuri; Las-Heras, Fernando; Räisänen, Antti V.

    2016-02-01

    A novel scheme for planar near-field phaseless antenna measurement based on off-axis holography is presented. Separation of the image terms of the hologram is artificially increased by multiplexing the measurements of two sub-sampled holograms generated with two 180° phase-shifted reference waves. Combination of both sub-sampled holograms produces replicas of the image terms at half a period distance of the originals in the spectral domain, while the amplitude of the original image terms is highly reduced, easing the filtering process of the desired replica. The higher separation of the image terms reduces overlapping making the method suitable also for the characterization of medium and low gain antennas in the near-field. As the separation is artificially increased, the reference antenna can be placed close to the antenna under test allowing to reduce the scan distance and the sensitivity to scan axis errors. Nevertheless, spatial multiplexing requires the retrieved data to be spatially low-pass filtered to remove the effect of the aliasing. Mirror reflection is used for illuminating the acquisition plane with the reference wave, being the phase shift achieved by means of a mechanical displacement of the mirror. The effect of the location of the reference antenna on the position and shape of the image terms and their replicas has been studied through numerical simulations for a setup in the W-band. Experimental validation of the method is presented for the characterization of three different antennas at 94 GHz.

  13. A novel image watermarking method based on singular value decomposition and digital holography

    NASA Astrophysics Data System (ADS)

    Cai, Zhishan

    2016-10-01

    According to the information optics theory, a novel watermarking method based on Fourier-transformed digital holography and singular value decomposition (SVD) is proposed in this paper. First of all, a watermark image is converted to a digital hologram using the Fourier transform. After that, the original image is divided into many non-overlapping blocks. All the blocks and the hologram are decomposed using SVD. The singular value components of the hologram are then embedded into the singular value components of each block using an addition principle. Finally, SVD inverse transformation is carried out on the blocks and hologram to generate the watermarked image. The watermark information embedded in each block is extracted at first when the watermark is extracted. After that, an averaging operation is carried out on the extracted information to generate the final watermark information. Finally, the algorithm is simulated. Furthermore, to test the encrypted image's resistance performance against attacks, various attack tests are carried out. The results show that the proposed algorithm has very good robustness against noise interference, image cut, compression, brightness stretching, etc. In particular, when the image is rotated by a large angle, the watermark information can still be extracted correctly.

  14. Study of 3D remote sensing system based on optical scanning holography

    NASA Astrophysics Data System (ADS)

    Zhao, Shihu; Yan, Lei

    2009-06-01

    High-precision and real-time remote sensing imaging system is an important part of remote sensing development. Holography is a method of wave front record and recovery which was presented by Dennis Gabor. As a new kind of holography techniques, Optical scanning holography (OSH) and remote sensing imaging are intended to be combined together and applied in acquisition and interference measurement of remote sensing. The key principles and applicability of OSH are studied and the mathematic relation between Fresnel Zone Plate number, numerical aperture and object distance was deduced, which are proved to be feasible for OSH to apply in large scale remote sensing. At last, a new three-dimensional reflected OSH remote sensing imaging system is designed with the combination of scanning technique to record hologram patterns of large scale remote sensing scenes. This scheme is helpful for expanding OSH technique to remote sensing in future.

  15. Tile-Based Two-Dimensional Phase Unwrapping for Digital Holography Using a Modular Framework

    PubMed Central

    Antonopoulos, Georgios C.; Steltner, Benjamin; Heisterkamp, Alexander; Ripken, Tammo; Meyer, Heiko

    2015-01-01

    A variety of physical and biomedical imaging techniques, such as digital holography, interferometric synthetic aperture radar (InSAR), or magnetic resonance imaging (MRI) enable measurement of the phase of a physical quantity additionally to its amplitude. However, the phase can commonly only be measured modulo 2π, as a so called wrapped phase map. Phase unwrapping is the process of obtaining the underlying physical phase map from the wrapped phase. Tile-based phase unwrapping algorithms operate by first tessellating the phase map, then unwrapping individual tiles, and finally merging them to a continuous phase map. They can be implemented computationally efficiently and are robust to noise. However, they are prone to failure in the presence of phase residues or erroneous unwraps of single tiles. We tried to overcome these shortcomings by creating novel tile unwrapping and merging algorithms as well as creating a framework that allows to combine them in modular fashion. To increase the robustness of the tile unwrapping step, we implemented a model-based algorithm that makes efficient use of linear algebra to unwrap individual tiles. Furthermore, we adapted an established pixel-based unwrapping algorithm to create a quality guided tile merger. These original algorithms as well as previously existing ones were implemented in a modular phase unwrapping C++ framework. By examining different combinations of unwrapping and merging algorithms we compared our method to existing approaches. We could show that the appropriate choice of unwrapping and merging algorithms can significantly improve the unwrapped result in the presence of phase residues and noise. Beyond that, our modular framework allows for efficient design and test of new tile-based phase unwrapping algorithms. The software developed in this study is freely available. PMID:26599984

  16. Optical sectioning using a digital Fresnel incoherent-holography-based confocal imaging system

    PubMed Central

    Kelner, Roy; Katz, Barak; Rosen, Joseph

    2015-01-01

    We propose a new type of confocal microscope using Fresnel incoherent correlation holography (FINCH). Presented here is a confocal configuration of FINCH using a phase pinhole and point illumination that is able to suppress out-of-focus information from the recorded hologram and hence combine the super-resolution capabilities of FINCH with the sectioning capabilities of confocal microscopy. PMID:26413560

  17. Dispersion-based stimulated Raman scattering spectroscopy, holography, and optical coherence tomography (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Robles, Francisco E.; Fischer, Martin C.; Warren, Warren S.

    2016-03-01

    Stimulated Raman scattering (SRS) enables fast, high resolution imaging of chemical constituents important to biological structures and functional processes. While this technology has shown remarkable potential, it is currently limited to point scanning and can only probe a few Raman bands at a time. In this work we take a fundamentally different approach to detecting the small nonlinear signals based on dispersion effects that accompany the loss/gain processes in SRS. We use a modified pump-probe system (pulses with duration of ~0.5 ps and 75 fs, respectively) with interferometric detection in the Fourier-domain to demonstrate that the dispersive measurements are more robust to noise (e.g., laser noise) compared to conventional amplitude measurements, which in turn permits facile spectral and spatial multiplexing. Results show that it is possible to assess a broadband dispersion spectrum (currently limited to ~400 cm-1) with a single laser shot or spectrometer acquisition (20-50 µs). For molecular imaging with broadband spectral information, we achieve spatial pixel rates of 2.5 kHz, and will discuss how this can be further improved to 20-50 kHz. We also combine SRS with optical coherence tomography (OCT) (molecular and structural information are rendered from the same data), which enables axial multiplexing by coherence gating and paves the way for volumetric biochemical imaging. The approach is tested on a thin water-and-oil phantom, a thick scattering polystyrene bead phantom, and thick freshly excised human adipose tissue. Finally, we will outline other opportunities for spatial multiplexing using wide-field holography and spectroscopic-OCT, which would massively parallelize the spatial and spectral information. The combination of dispersion-based SRS and phase imaging has the potential to enable faster wide-area and volumetric molecular imaging. Such methods would be valuable in a clinical setting for many applications.

  18. Analysis on the lateral resolution of optical scanning holography system based on random phase encoding using restricted pupils

    NASA Astrophysics Data System (ADS)

    Wang, Yun; Hu, Jian-Ping; Yuan, Sheng; Xie, Jian; Guo, Xue-Fan; Zhang, Luo-Zhi; Wan, Dao-Ming; Hu, You-Jun; Zhou, Xin

    2014-05-01

    In this paper, we analyze the point spread function of optical scanning holography (OSH) system based on random phase encoding (RPE-OSH) with restricted pupils and compare the lateral resolution of RPE-OSH system with the one of conventional OSH system by the definition of Rayleigh criterion. The results show that the main lobe width of RPE-OSH system is much narrower than that of the conventional OSH system under the same conditions; thus, the reconstructed image in RPE-OSH system has a higher lateral resolution and reserves more detailed information. This conclusion is verified by numerical simulations of the Cymbella cymbiformis image reconstruction.

  19. High-resolution parallel phase-shifting digital holography using a low-resolution phase-shifting array device based on image inpainting.

    PubMed

    Jiao, Shuming; Zou, Wenbin

    2017-02-01

    Parallel phase-shifting digital holography can record high-quality holograms efficiently from fast-moving objects in a dynamic scene. However, a phase-shifting array device with a cell size identical to image sensors is required, which imposes difficulty in practice. This Letter proposes a novel scheme to employ a low-resolution phase-shifting array device to achieve high-resolution parallel phase-shifting digital holography, based on image inpainting performed on incomplete holograms. The experimental results validate the effectiveness of the proposed scheme.

  20. Incoherent holography

    NASA Astrophysics Data System (ADS)

    Abramson, Nils H.

    2000-10-01

    Dennis Gabor invented in-line holography in 1947, but at that time the coherent light from a laser did not yet exist and therefore the holograms he produced were of very low quality. When the laser was born in 1960 beautiful 3-D off- center holograms were for the first time produced by Emmett Leith and Juris Upatnieks. However, already as early as 1934 the inventor and artist Hans Weil patented a method to produce simple pictures that appeared floating in space, by scratching a transparent or metallic surface in certain directions. In 1995 William J. Beaty published a method for Hand-Drawn Holograms. Then it became possible for any artist to draw his own 3-D pictures of simple objects and using his ingenious techniques these hand drawn images will mimic many of the qualities of ordinary holograms.

  1. Emerging holography

    SciTech Connect

    Erlich, Joshua; Kribs, Graham D.; Low, Ian

    2006-05-01

    We rederive AdS/CFT predictions for infrared two-point functions by an entirely four-dimensional approach, without reference to holography. This approach, originally due to Migdal in the context of QCD, utilizes an extrapolation from the ultraviolet to the infrared using a Pade approximation of the two-point function. We show that the Pade approximation and AdS/CFT give the same leading order predictions, and we discuss including power corrections such as those due to condensates of gluons and quarks in QCD. At finite order the Pade approximation provides a gauge invariant regularization of a higher dimensional gauge theory in the spirit of deconstructed extra dimensions. The radial direction of anti-de Sitter space emerges naturally in this approach.

  2. Holography and tomography

    SciTech Connect

    Howells, M.

    1997-02-01

    This session includes a collection of outlines of pertinent information, diagrams, graphs, electron micrographs, and color photographs pertaining to historical aspects and recent advances in the development of X-ray Gabor Holography. Many of the photographs feature or pertain to instrumentation used in holography, tomography, and cryo-holography.

  3. Differential-interference-contrast digital in-line holography microscopy based on a single-optical-element.

    PubMed

    Zhang, Yuchao; Xie, Changqing

    2015-11-01

    Both digital in-line holography (DIH) and zone plate-based microscopy have received considerable interest as powerful imaging tools. However, the former suffers from a twin-image noise problem. The latter suffers from low efficiency and difficulty in fabrication. Here, we present an effective and efficient phase-contrast imaging approach, named differential-interference-contrast digital in-line holography (DIC-DIH), by using a single optical element to split the incident light into a plane wave and a converging spherical wave and generate a two-dimensional (2D) DIC effect simultaneously. Specifically, to improve image contrast, we present a new single optical element, termed 2D DIC compound photon sieves, by combining two overlaid binary gratings and a compound photon sieve through two logical XOR operations. The proof-of-concept experiments demonstrate that the proposed technique can eliminate the twin-image noise problem and improve image contrast with high efficiency. Additionally, we present an example of the phase-contrast imaging nonuniform thick photoresist development process.

  4. Introducing passive acoustic filter in acoustic based condition monitoring: Motor bike piston-bore fault identification

    NASA Astrophysics Data System (ADS)

    Jena, D. P.; Panigrahi, S. N.

    2016-03-01

    Requirement of designing a sophisticated digital band-pass filter in acoustic based condition monitoring has been eliminated by introducing a passive acoustic filter in the present work. So far, no one has attempted to explore the possibility of implementing passive acoustic filters in acoustic based condition monitoring as a pre-conditioner. In order to enhance the acoustic based condition monitoring, a passive acoustic band-pass filter has been designed and deployed. Towards achieving an efficient band-pass acoustic filter, a generalized design methodology has been proposed to design and optimize the desired acoustic filter using multiple filter components in series. An appropriate objective function has been identified for genetic algorithm (GA) based optimization technique with multiple design constraints. In addition, the sturdiness of the proposed method has been demonstrated in designing a band-pass filter by using an n-branch Quincke tube, a high pass filter and multiple Helmholtz resonators. The performance of the designed acoustic band-pass filter has been shown by investigating the piston-bore defect of a motor-bike using engine noise signature. On the introducing a passive acoustic filter in acoustic based condition monitoring reveals the enhancement in machine learning based fault identification practice significantly. This is also a first attempt of its own kind.

  5. Single-shot polarization-imaging digital holography based on simultaneous phase-shifting interferometry.

    PubMed

    Tahara, Tatsuki; Awatsuji, Yasuhiro; Shimozato, Yuki; Kakue, Takashi; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2011-08-15

    We propose single-shot digital holography which is capable of simultaneously capturing both the information of multiple phase-shifted holograms and the distribution of the polarization. In this technique, a single image sensor records both the information required for phase-shifting interferometry and that of the polarization states of objects using an array of polarizers. The essence of the technique is the capability of imaging the distribution of the polarization of three-dimensional objects with a single-shot exposure by using the space-division multiplexing of holograms. The validity of the proposed technique was confirmed by the preliminary experiments.

  6. Guest Editoria Holography A Dedication To Dennis Gabor

    NASA Astrophysics Data System (ADS)

    Wyant, James C.; Chen, Chungte T.; Reynolds, George O.

    1980-10-01

    We thought it was time to bring the readers of Optical Engineering up to date on the new developments in holography, as was done exactly five years ago with the September/October 1975 special issue. The seeds for this special issue were sown during the 1978 Gordon Conference on Coherent Optics and Holography held at the Miramar Hotel in Santa Barbara, California. The conference clearly demonstrated, through the discussion of many interesting research and development applications, that holography is alive and well. For example, artists have discovered holography as a new medium and there is a museum for displaying new holographic developments and inventions. In addition to the opening of the New York museum where artists and patrons are thoroughly enjoying holography, the past five years have witnessed the publication of the Handbook of Optical Holography, continuing issues of the Acoustical Holography proceedings, the gathering of scientists to exchange ideas at three Gordon Conferences in 1976, 1978, and 1980, and the SPIE conference on holography held in Los Angeles in February 1980.

  7. Structure borne noise analysis using Helmholtz equation least squares based forced vibro acoustic components

    NASA Astrophysics Data System (ADS)

    Natarajan, Logesh Kumar

    This dissertation presents a structure-borne noise analysis technology that is focused on providing a cost-effective noise reduction strategy. Structure-borne sound is generated or transmitted through structural vibration; however, only a small portion of the vibration can effectively produce sound and radiate it to the far-field. Therefore, cost-effective noise reduction is reliant on identifying and suppressing the critical vibration components that are directly responsible for an undesired sound. However, current technologies cannot successfully identify these critical vibration components from the point of view of direct contribution to sound radiation and hence cannot guarantee the best cost-effective noise reduction. The technology developed here provides a strategy towards identifying the critical vibration components and methodically suppressing them to achieve a cost-effective noise reduction. The core of this technology is Helmholtz equation least squares (HELS) based nearfield acoustic holography method. In this study, the HELS formulations derived in spherical co-ordinates using spherical wave expansion functions utilize the input data of acoustic pressures measured in the nearfield of a vibrating object to reconstruct the vibro-acoustic responses on the source surface and acoustic quantities in the far field. Using these formulations, three steps were taken to achieve the goal. First, hybrid regularization techniques were developed to improve the reconstruction accuracy of normal surface velocity of the original HELS method. Second, correlations between the surface vibro-acoustic responses and acoustic radiation were factorized using singular value decomposition to obtain orthogonal basis known here as the forced vibro-acoustic components (F-VACs). The F-VACs enables one to identify the critical vibration components for sound radiation in a similar manner that modal decomposition identifies the critical natural modes in a structural vibration. Finally

  8. 48 Years with holography

    NASA Astrophysics Data System (ADS)

    Kubota, Toshihiro

    2014-11-01

    The invention of holography was epoch-making in optics. Although the research on holography has cycled through active and stagnant periods, holography has gradually become a practical technique thanks to researchers' steady efforts. The technique has many attractive features and is used in many fields nowadays. The latest developments in high-definition image sensors and ultrashort pulsed lasers have given rise to a new possibility of holography. I have been engaged in the research and development of holography since I knew it by casual opportunity. In this paper, the research in early stages of holography is briefly described, and some of my basic and applied research in which I have so far engaged are introduced.

  9. Acoustic microscope based on magneto-elastic wave phase conjugator

    NASA Astrophysics Data System (ADS)

    Brysev, A.; Krutyansky, L.; Pernod, P.; Preobrazhensky, V.

    2000-05-01

    Acoustic C-scan imaging (acoustic microscopy) by means of supercritical parametric wave phase conjugation (WPC) is studied experimentally. A phase conjugator based on a magneto-acoustic active material is used for compensating phase distortions introduced by solid and polymer aberration layers covering objects (electronic integrated circuits as examples). Improvement of images is demonstrated on an acoustic microscope, operating at a frequency of 10 MHz.

  10. Metasurfaces-based holography and beam shaping: engineering the phase profile of light

    NASA Astrophysics Data System (ADS)

    Scheuer, Jacob

    2017-01-01

    The ability to engineer and shape the phase profile of optical beams is in the heart of any optical element. Be it a simple lens or a sophisticated holographic element, the functionality of such components is dictated by their spatial phase response. In contrast to conventional optical components which rely on thickness variation to induce a phase profile, metasurfaces facilitate the realization of arbitrary phase distributions using large arrays with sub-wavelength and ultrathin (tens of nanometers) features. Such components can be easily realized using a single lithographic step and is highly suited for patterning a variety of substrates, including nonplanar and soft surfaces. In this article, we review the recent developments, potential, and opportunities of metasurfaces applications. We focus primarily on flat optical devices, holography, and beam-shaping applications as these are the key ingredients needed for the development of a new generation of optical devices which could find widespread applications in photonics.

  11. Metasurfaces-based holography and beam shaping: engineering the phase profile of light

    NASA Astrophysics Data System (ADS)

    Scheuer, Jacob

    2016-08-01

    The ability to engineer and shape the phase profile of optical beams is in the heart of any optical element. Be it a simple lens or a sophisticated holographic element, the functionality of such components is dictated by their spatial phase response. In contrast to conventional optical components which rely on thickness variation to induce a phase profile, metasurfaces facilitate the realization of arbitrary phase distributions using large arrays with sub-wavelength and ultrathin (tens of nanometers) features. Such components can be easily realized using a single lithographic step and is highly suited for patterning a variety of substrates, including nonplanar and soft surfaces. In this article, we review the recent developments, potential, and opportunities of metasurfaces applications. We focus primarily on flat optical devices, holography, and beam-shaping applications as these are the key ingredients needed for the development of a new generation of optical devices which could find widespread applications in photonics.

  12. Common-path on-axis Fresnel holography based on a pinhole array plate.

    PubMed

    Zhang, Xin-Ting; Guo, Cheng-Shan

    2015-01-01

    A common-path and on-axis configuration for improving the resolution power of a lensless Fresnel holographic imaging system is proposed. In this configuration, a pinhole array plate (PAP) is inserted between the object and the recording plane. We demonstrated that the complex amplitude of the object wave can be directly extracted from a single Fresnel hologram of the object wave sampled by the PAP, and the numerical aperture of the effective imaging system can be increased because of the diffraction effect of the pinhole array. It may provide one approach for improving the capabilities of digital holography available for a wide range of wavelengths from far-infrared to x-ray and electron beams.

  13. Parallel three-step phase-shifting digital holography.

    PubMed

    Awatsuji, Yasuhiro; Fujii, Atsushi; Kubota, Toshihiro; Matoba, Osamu

    2006-05-01

    We propose parallel three-step phase-shifting digital holography as a technique capable of noiseless instantaneous measurement of three-dimensional objects based on phase-shifting interferometry. The proposed digital holography carries out three-step phase shifting at the same time by using a phase-shifting array device located in the reference beam. The array device has a periodic three-step phase distribution, and its configuration is simplified compared with that required for conventional parallel phase-shifting digital holography. Therefore the optical system of the proposed parallel phase-shifting digital holography is more suitable for the realization of the proposed holography. We conduct both a numerical simulation and a preliminary experiment. The results of the simulation and experiment agree well with those of the conventional phase-shifting method and are superior to the results obtained by conventional digital holography by using the Fresnel transform alone. Thus the effectiveness of the proposed technique is verified.

  14. Helioseismic Holography and a Study of the Process of Magnetic Flux Disappearance in Canceling Bipoles

    NASA Technical Reports Server (NTRS)

    Lindsey, Charles; Harvey, Karen L.; Braun, D.; Jones, H. P.; Penn, M.; Hassler, D.

    2001-01-01

    Project 1: We have developed and applied a technique of helioseismic holography along the lines of originally set out in our proposal. The result of the application of this diagnostic technique to solar activity and the quiet Sun has produced a number of important discoveries: (1) acoustic moats surrounding sunspots; (2) acoustic glories surround large active regions; (3) acoustic condensations beneath active regions; and (4) temporally-resolve acoustic images of a solar flare. These results have been published in a series of papers in the Astrophysical Journal. We think that helioseismic holography is now established as the most powerful and discriminating diagnostic in local helioseismology. Project 2: We conducted a collaborative observational program to define the physical character and magnetic geometry of canceling magnetic bipoles aimed at determining if the cancellation process is the result of submergence of magnetic fields. This assessment is based on ground-based observations combining photospheric and chromospheric magnetograms from NSO/KP, BBSO, and SOHO-MDI, and EUV and X-ray images from SOHO EIT/CDS, Yohkoh/SXT, and TRACE. Our study involves the analysis of data taken during three observing campaigns to define the height structure of canceling bipoles inferred from magnetic field and intensity images, and how this varies with time. We find that some canceling bipoles can be explained by the submerge of their magnetic flux. A paper on the results of this analysis will be presented at an upcoming scientific meeting and be written up for publication.

  15. Auditorium acoustics evaluation based on simulated impulse response

    NASA Astrophysics Data System (ADS)

    Wu, Shuoxian; Wang, Hongwei; Zhao, Yuezhe

    2001-05-01

    The impulse responses and other acoustical parameters of Huangpu Teenager Palace in Guangzhou were measured. Meanwhile, the acoustical simulation and auralization based on software ODEON were also made. The comparison between the parameters based on computer simulation and measuring is given. This case study shows that auralization technique based on computer simulation can be used for predicting the acoustical quality of a hall at its design stage.

  16. Fiber based photonic-crystal acoustic sensor

    NASA Astrophysics Data System (ADS)

    Kilic, Onur

    -crystal reflector embedded in a compliant silicon diaphragm placed at the tip of a single-mode fiber. Measurements in air indicate that this sensor has a relatively uniform frequency response up to at least 50 kHz, which is at least one order of magnitude higher than existing all-fiber acoustic sensors. This sensor was also shown to be able to detect pressures as low as 18 muPa/Hz 1/2. This limit is four orders of magnitude lower than in similar types of acoustic fiber sensors that are based on a deflectable diaphragm at the fiber end. This significant improvement is to a large extent due to the higher reflectivity of the reflectors, which is itself due to the use of a photonic crystal. Through a modification in the design, such a sensor can also be used in water. In addition to the high compliance of the diaphragm, the advantage for using the photonic-crystal slab is that the holes provide a venting channel for pressure equalization. As a result, the hydrophone can be employed in deep-sea applications without suffering from the high static pressure. Measurements in water over the range of 10 kHz-50 kHz show that this hydrophone has a minimum detectable pressure of only 10 muPa/Hz1/2, close to the ambient thermal-noise level. A model was developed to show that after optimization to ocean acoustics, the sensor has a theoretical minimum detectable pressure that follows the minimum ambient noise spectrum of the ocean in the bandwidth of 1 Hz-100 kHz. This makes this sensor extremely broadband compared to commercial fiber hydrophones, which are bulky and poorly responsive to frequencies above a few hundred Hz, since they require a long length of fiber. By placing several such sensors with different acoustic power ranges within a single sensor chip, this hydrophone is capable of exhibiting a dynamic range in the excess of 200 dB (1010).

  17. Surpassing digital holography limits by lensless object scanning holography.

    PubMed

    Micó, Vicente; Ferreira, Carlos; García, Javier

    2012-04-23

    We present lensless object scanning holography (LOSH) as a fully lensless method, capable of improving image quality in reflective digital Fourier holography, by means of an extremely simplified experimental setup. LOSH is based on the recording and digital post-processing of a set of digital lensless holograms and results in a synthetic image with improved resolution, field of view (FOV), signal-to-noise ratio (SNR), and depth of field (DOF). The superresolution (SR) effect arises from the generation of a synthetic aperture (SA) based on the linear movement of the inspected object. The same scanning principle enlarges the object FOV. SNR enhancement is achieved by speckle suppression and coherent artifacts averaging due to the coherent addition of the multiple partially overlapping bandpass images. And DOF extension is performed by digital refocusing to different object's sections. Experimental results showing an impressive image quality improvement are reported for a one-dimensional reflective resolution test target.

  18. Denoising algorithm based on edge extraction and wavelet transform in digital holography

    NASA Astrophysics Data System (ADS)

    Zhang, Ming; Sang, Xin-zhu; Leng, Jun-min; Cao, Xue-mei

    2013-08-01

    Digital holography is a kind of coherent imaging method and inevitably affected by many factors in the process of recording. One of dominant problems is the speckle noise, which is essentially nonlinear multiplicative noise related to signals. So it is more difficult to remove than additive noise. Due to the noise pollution, the low resolution of image reconstructed is caused. A new solution for suppressing speckle noise in digital hologram is presented, which combines Canny filtering algorithm with wavelet threshold denoising algorithm. Canny filter is used to obtain the edge detail. Wavelet transformation performs denoising. In order to suppress speckle effectively and retain the image details as much as possible, Neyman-Pearson (N-P) criterion is introduced to estimate wavelet coefficient in every scale. An improved threshold function is proposed, whose curve is smoother. The reconstructed image is achieved by merging the denoised image with the edge details. Experimental results and performance parameters of the proposed algorithm are discussed and compared with other methods, which shows that the presented approach can not only effectively eliminate speckle noise, but also retain useful signals and edge information simultaneously.

  19. Lock-in camera based heterodyne holography for ultrasound-modulated optical tomography inside dynamic scattering media.

    PubMed

    Liu, Yan; Shen, Yuecheng; Ma, Cheng; Shi, Junhui; Wang, Lihong V

    2016-06-06

    Ultrasound-modulated optical tomography (UOT) images optical contrast deep inside scattering media. Heterodyne holography based UOT is a promising technique that uses a camera for parallel speckle detection. In previous works, the speed of data acquisition was limited by the low frame rates of conventional cameras. In addition, when the signal-to-background ratio was low, these cameras wasted most of their bits representing an informationless background, resulting in extremely low efficiencies in the use of bits. Here, using a lock-in camera, we increase the bit efficiency and reduce the data transfer load by digitizing only the signal after rejecting the background. Moreover, compared with the conventional four-frame based amplitude measurement method, our single-frame method is more immune to speckle decorrelation. Using lock-in camera based UOT with an integration time of 286 μs, we imaged an absorptive object buried inside a dynamic scattering medium exhibiting a speckle correlation time ([Formula: see text]) as short as 26 μs. Since our method can tolerate speckle decorrelation faster than that found in living biological tissue ([Formula: see text] ∼ 100-1000 μs), it is promising for in vivo deep tissue non-invasive imaging.

  20. Lock-in camera based heterodyne holography for ultrasound-modulated optical tomography inside dynamic scattering media

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Shen, Yuecheng; Ma, Cheng; Shi, Junhui; Wang, Lihong V.

    2016-06-01

    Ultrasound-modulated optical tomography (UOT) images optical contrast deep inside scattering media. Heterodyne holography based UOT is a promising technique that uses a camera for parallel speckle detection. In previous works, the speed of data acquisition was limited by the low frame rates of conventional cameras. In addition, when the signal-to-background ratio was low, these cameras wasted most of their bits representing an informationless background, resulting in extremely low efficiencies in the use of bits. Here, using a lock-in camera, we increase the bit efficiency and reduce the data transfer load by digitizing only the signal after rejecting the background. Moreover, compared with the conventional four-frame based amplitude measurement method, our single-frame method is more immune to speckle decorrelation. Using lock-in camera based UOT with an integration time of 286 μs, we imaged an absorptive object buried inside a dynamic scattering medium exhibiting a speckle correlation time ( τ c ) as short as 26 μs. Since our method can tolerate speckle decorrelation faster than that found in living biological tissue ( τ c ˜ 100-1000 μs), it is promising for in vivo deep tissue non-invasive imaging.

  1. Standing surface acoustic wave based cell coculture.

    PubMed

    Li, Sixing; Guo, Feng; Chen, Yuchao; Ding, Xiaoyun; Li, Peng; Wang, Lin; Cameron, Craig E; Huang, Tony Jun

    2014-10-07

    Precise reconstruction of heterotypic cell-cell interactions in vitro requires the coculture of different cell types in a highly controlled manner. In this article, we report a standing surface acoustic wave (SSAW)-based cell coculture platform. In our approach, different types of cells are patterned sequentially in the SSAW field to form an organized cell coculture. To validate our platform, we demonstrate a coculture of epithelial cancer cells and endothelial cells. Real-time monitoring of cell migration dynamics reveals increased cancer cell mobility when cancer cells are cocultured with endothelial cells. Our SSAW-based cell coculture platform has the advantages of contactless cell manipulation, high biocompatibility, high controllability, simplicity, and minimal interference of the cellular microenvironment. The SSAW technique demonstrated here can be a valuable analytical tool for various biological studies involving heterotypic cell-cell interactions.

  2. Standing Surface Acoustic Wave Based Cell Coculture

    PubMed Central

    2015-01-01

    Precise reconstruction of heterotypic cell–cell interactions in vitro requires the coculture of different cell types in a highly controlled manner. In this article, we report a standing surface acoustic wave (SSAW)-based cell coculture platform. In our approach, different types of cells are patterned sequentially in the SSAW field to form an organized cell coculture. To validate our platform, we demonstrate a coculture of epithelial cancer cells and endothelial cells. Real-time monitoring of cell migration dynamics reveals increased cancer cell mobility when cancer cells are cocultured with endothelial cells. Our SSAW-based cell coculture platform has the advantages of contactless cell manipulation, high biocompatibility, high controllability, simplicity, and minimal interference of the cellular microenvironment. The SSAW technique demonstrated here can be a valuable analytical tool for various biological studies involving heterotypic cell–cell interactions. PMID:25232648

  3. Sheathless Size-Based Acoustic Particle Separation

    PubMed Central

    Guldiken, Rasim; Jo, Myeong Chan; Gallant, Nathan D.; Demirci, Utkan; Zhe, Jiang

    2012-01-01

    Particle separation is of great interest in many biological and biomedical applications. Flow-based methods have been used to sort particles and cells. However, the main challenge with flow based particle separation systems is the need for a sheath flow for successful operation. Existence of the sheath liquid dilutes the analyte, necessitates precise flow control between sample and sheath flow, requires a complicated design to create sheath flow and separation efficiency depends on the sheath liquid composition. In this paper, we present a microfluidic platform for sheathless particle separation using standing surface acoustic waves. In this platform, particles are first lined up at the center of the channel without introducing any external sheath flow. The particles are then entered into the second stage where particles are driven towards the off-center pressure nodes for size based separation. The larger particles are exposed to more lateral displacement in the channel due to the acoustic force differences. Consequently, different-size particles are separated into multiple collection outlets. The prominent feature of the present microfluidic platform is that the device does not require the use of the sheath flow for positioning and aligning of particles. Instead, the sheathless flow focusing and separation are integrated within a single microfluidic device and accomplished simultaneously. In this paper, we demonstrated two different particle size-resolution separations; (1) 3 μm and 10 μm and (2) 3 μm and 5 μm. Also, the effects of the input power, the flow rate, and particle concentration on the separation efficiency were investigated. These technologies have potential to impact broadly various areas including the essential microfluidic components for lab-on-a-chip system and integrated biological and biomedical applications. PMID:22368502

  4. Acoustic transducer based on dielectric elastomers

    NASA Astrophysics Data System (ADS)

    Graf, Christian; Maas, Jügen

    2012-04-01

    Dielectric electroactive polymers are thin films based on elastomeric material coated with compliant and conductive electrodes. By applying an electrical field, the polymer performs large deformations, which can be utilized to generate sound waves. When using such kind of electrostatic loudspeakers, no additional resonating sound boxes are required and the vibrating mass is very lightweight, resulting in an excellent impulse and wide-band frequency response. For the loudspeaker's operation both an electrical bias voltage and a mechanical bias stress have to be applied. In this contribution different possibilities are presented to generate the mechanical bias stress. The design of an appropriate power electronics for the acoustic transducer, which is build of standard components, is also described. Finally, the loudspeaker concepts are evaluated by experiments in an anechoic room.

  5. Wavelet-based acoustic recognition of aircraft

    SciTech Connect

    Dress, W.B.; Kercel, S.W.

    1994-09-01

    We describe a wavelet-based technique for identifying aircraft from acoustic emissions during take-off and landing. Tests show that the sensor can be a single, inexpensive hearing-aid microphone placed close to the ground the paper describes data collection, analysis by various technique, methods of event classification, and extraction of certain physical parameters from wavelet subspace projections. The primary goal of this paper is to show that wavelet analysis can be used as a divide-and-conquer first step in signal processing, providing both simplification and noise filtering. The idea is to project the original signal onto the orthogonal wavelet subspaces, both details and approximations. Subsequent analysis, such as system identification, nonlinear systems analysis, and feature extraction, is then carried out on the various signal subspaces.

  6. Particle and flow field holography

    NASA Astrophysics Data System (ADS)

    Trolinger, J. D.

    1985-01-01

    The current status of particle field and flow field holography is examined, and the methods based on the principles of either class of imagery are described. Special consideration is given to the automated data reduction technology. Current applications of flow diagnostics, which can provide thousands of holograms during a one-day experiment, include NASA applications in wind tunnel holography, in a Laser Doppler Velocimeter, in holographic movies, and in an optical device for recording crystal growth at zero gravity, to be used in the Space Lab 3 shuttle mission scheduled for May 1985. Military applications of the flow diagnostics include the use of holographic tomography for visualizing flow fields around airborne structures, in wind tunnels, and in the analyses of rocket exhausts and gun ranges. The information provided by the particle sizing holography, concerning the size, shape, number, and velocity of particles and the records of the particle break-up phenomenon, can be used in various military field oriented and airborne applications and in meteorology and environment protection science.

  7. Holography: childrens' window to relativity

    NASA Astrophysics Data System (ADS)

    MacShane, James E.

    1995-02-01

    This paper is concerned with the development of the concept of natural education. Psychology has discovered that all humans learn intuitively the cultural concepts of time from birth to eight and one-half to ten years of age. Einstein showed us that this must also be the natural time for the development of spatial concepts. The importance of this has been dramatized for me in the past eight years that I have been developing the Laser Arts and Holography Programs and Workshops. I have worked with over 100,000 students kindergarten through eighth grade. I have worked with 175 students age 8 to 10 in three hour and one half workshops specifically on the development of time and space concepts. The concepts developed are based upon the vast amount of psychological evidence related to the natural development of time and space understandings, Dr. Nils Abramson's 'Light in Flight' and subsequent work on the clarification of relativity through holography, and Maria Montessori's method of Scientific Education. The paper also demonstrates the natural method of teaching science to younger students is to teach scientifically. All of the research which has been done in the past 100 years has been used by the educational institutions to try to improve the system. What has not been done is changing the system to how humans learn. Because of the perceived hi-tech nature of the program I am able to dramatize the potential. An outline for a holography curriculum kindergarten through eighth grade is included.

  8. Optical structure based on the acoustic Helmholtz resonator

    NASA Astrophysics Data System (ADS)

    Chevalier, Paul; Bouchon, Patrick; Pelouard, Jean-Luc; Pardo, Fabrice; Haidar, Riad

    2015-02-01

    Here, based on an analogy between acoustics and electromagnetism wave equations, we present an electromagnetic resonator analogous to the Helmholtz resonator in acoustics. This structure is made of a tiny slit above a box and exhibits appealing properties for applications such as thermal emission, bio-sensing or spectroscopy.

  9. Acoustic wave based MEMS devices for biosensing applications.

    PubMed

    Voiculescu, Ioana; Nordin, Anis Nurashikin

    2012-03-15

    This paper presents a review of acoustic-wave based MEMS devices that offer a promising technology platform for the development of sensitive, portable, real-time biosensors. MEMS fabrication of acoustic wave based biosensors enables device miniaturization, power consumption reduction and integration with electronic circuits. For biological applications, the biosensors are integrated in a microfluidic system and the sensing area is coated with a biospecific layer. When a bioanalyte interacts with the sensing layer, mass and viscosity variations of the biospecific layer can be detected by monitoring changes in the acoustic wave properties such as velocity, attenuation, resonant frequency and delay time. Few types of acoustic wave devices could be integrated in microfluidic systems without significant degradation of the quality factor. The acoustic wave based MEMS devices reported in the literature as biosensors and presented in this review are film bulk acoustic wave resonators (FBAR), surface acoustic waves (SAW) resonators and SAW delay lines. Different approaches to the realization of FBARs, SAW resonators and SAW delay lines for various biochemical applications are presented. Methods of integration of the acoustic wave MEMS devices in the microfluidic systems and functionalization strategies will be also discussed.

  10. Acoustic logic gates and Boolean operation based on self-collimating acoustic beams

    NASA Astrophysics Data System (ADS)

    Zhang, Ting; Cheng, Ying; Guo, Jian-zhong; Xu, Jian-yi; Liu, Xiao-jun

    2015-03-01

    The reveal of self-collimation effect in two-dimensional (2D) photonic or acoustic crystals has opened up possibilities for signal manipulation. In this paper, we have proposed acoustic logic gates based on the linear interference of self-collimated beams in 2D sonic crystals (SCs) with line-defects. The line defects on the diagonal of the 2D square SCs are actually functioning as a 3 dB splitter. By adjusting the phase difference between two input signals, the basic Boolean logic functions such as XOR, OR, AND, and NOT are achieved both theoretically and experimentally. Due to the non-diffracting property of self-collimation beams, more complex Boolean logic and algorithms such as NAND, NOR, and XNOR can be realized by cascading the basic logic gates. The achievement of acoustic logic gates and Boolean operation provides a promising approach for acoustic signal computing and manipulations.

  11. Nonlinear acoustic fields in acoustic metamaterial based on a cylindrical pipe with periodically arranged side holes.

    PubMed

    Fan, Li; Ge, Huan; Zhang, Shu-yi; Gao, Hai-fei; Liu, Yong-hui; Zhang, Hui

    2013-06-01

    Nonlinear acoustic fields in transmission-line acoustic metamaterials based on a cylindrical pipe with periodically arranged side holes are studied, in which the dispersions and characteristic parameters of the nonlinear acoustic waves are obtained with the Bloch theory, and meanwhile the distributions of the fundamental wave (FW) and second harmonic wave (SHW) in the metamaterial are simulated. Three characteristic frequency bands are defined according to the relations between the frequencies of the FW, SHW, and the low-frequency forbidden band (LFB) in the metamaterial. Especially, when the FW is in the LFB while the SHW is outside the LFB, the SHW can transmit through the metamaterial although the FW is blocked, which exhibits the possibility to extract the information from the SHW instead of the FW. In addition, experiments are carried out to measure the distributions of the acoustic pressures for the FW and SHW along the metamaterial and the experimental results are in agreement with the theory.

  12. Acoustic logic gates and Boolean operation based on self-collimating acoustic beams

    SciTech Connect

    Zhang, Ting; Xu, Jian-yi; Cheng, Ying Liu, Xiao-jun; Guo, Jian-zhong

    2015-03-16

    The reveal of self-collimation effect in two-dimensional (2D) photonic or acoustic crystals has opened up possibilities for signal manipulation. In this paper, we have proposed acoustic logic gates based on the linear interference of self-collimated beams in 2D sonic crystals (SCs) with line-defects. The line defects on the diagonal of the 2D square SCs are actually functioning as a 3 dB splitter. By adjusting the phase difference between two input signals, the basic Boolean logic functions such as XOR, OR, AND, and NOT are achieved both theoretically and experimentally. Due to the non-diffracting property of self-collimation beams, more complex Boolean logic and algorithms such as NAND, NOR, and XNOR can be realized by cascading the basic logic gates. The achievement of acoustic logic gates and Boolean operation provides a promising approach for acoustic signal computing and manipulations.

  13. Underwater holography: past and future

    NASA Astrophysics Data System (ADS)

    Watson, John

    2006-05-01

    100 m and over 300 holograms recorded. However, the HoloMar camera is physically large and heavy and difficult to deploy. It is also based on the use of photographic emulsions to record the holograms. To overcome some of these difficulties we are now developing a new holographic camera (eHoloCam) based on digital holography. In digital or "eHolography", a hologram is directly electronically recorded onto a CCD or CMOS sensor and then numerically reconstructed by simulation of the optical hologram reconstruction. The immediate advantages of this new camera are compactness, ease-of-use and speed of response, but at the expense of restricted off-axis recording angles and reduced recording volume. In this paper we describe both approaches, the use of holography for analysis of marine organisms and the results obtained in the field. We also describe recent work, using both photo and digital holography, to study the behaviour of sediments in river estuaries and outline future applications of underwater holography.

  14. An Introduction to Educational Holography.

    ERIC Educational Resources Information Center

    Lloyd, R. Scott

    Holograms are capable of taking the two-dimensional ways of envisioning information to another dimension of presentation, representation, and conceptualization. Educational holography is joining display holography, holographic testing of materials, and holographic optical elements as a fourth major field in holography. Holograms are explored as…

  15. Optimizing the diffraction efficiency of LCOS-based holography with anomalous reflection by gradient meta-surface

    NASA Astrophysics Data System (ADS)

    Shen, Chuan; Liu, Kaifeng; Wei, Sui; Ni, Lei; Wang, Hao

    2015-05-01

    Meta-surface offers an innovative approach to manipulate light with anomalous capabilities. We discuss the possibility of inserting a specially designed gradient meta-surface into the pixel architecture of the liquid crystal on silicon (LCOS) for the purpose of optimizing the diffraction efficiency of LCOS-based holography. The pixels in LCOS with feature size approaching the order of visible light wavelength could provide large diffraction angle, unfortunately, scaling down the pixel size would reduce the efficiency of the first diffraction we desired. The metal-insulator-metal (MIM) structure served as the unit cell of meta-surface consists of three layer, i.e., the subwavelength metal nanobrick with varying geometrical parameter and the continuous metal film separated by the insulator layer. A linear phase gradient is exhibited by the unit cells in each pixel period. When illuminated by a polarized incident light, the MIM structure, where a magnetic resonance is created at a particular frequency, can offer an anomalous reflection with high-efficiency and acts as a flat blazed grating. Finally, the light are supposed be diverted to the desired first diffraction. The properties of potential metal, such as Au, Ag, and Al, served as the plasmonic material and suitable insulator have been studied to configure the MIM structure accurately. Investigations are numerically carried out to observe the effects on the distribution of liquid crystal director with TechWiz Software and to obtain the relative diffraction efficiency by using FDTD software. Compared with the conventional LCOS device, the optimization of the diffraction efficiency has been achieved by our proposed structure.

  16. Compact, light-weight and cost-effective microscope based on lensless incoherent holography for telemedicine applications.

    PubMed

    Mudanyali, Onur; Tseng, Derek; Oh, Chulwoo; Isikman, Serhan O; Sencan, Ikbal; Bishara, Waheb; Oztoprak, Cetin; Seo, Sungkyu; Khademhosseini, Bahar; Ozcan, Aydogan

    2010-06-07

    Despite the rapid progress in optical imaging, most of the advanced microscopy modalities still require complex and costly set-ups that unfortunately limit their use beyond well equipped laboratories. In the meantime, microscopy in resource-limited settings has requirements significantly different from those encountered in advanced laboratories, and such imaging devices should be cost-effective, compact, light-weight and appropriately accurate and simple to be usable by minimally trained personnel. Furthermore, these portable microscopes should ideally be digitally integrated as part of a telemedicine network that connects various mobile health-care providers to a central laboratory or hospital. Toward this end, here we demonstrate a lensless on-chip microscope weighing approximately 46 grams with dimensions smaller than 4.2 cm x 4.2 cm x 5.8 cm that achieves sub-cellular resolution over a large field of view of approximately 24 mm(2). This compact and light-weight microscope is based on digital in-line holography and does not need any lenses, bulky optical/mechanical components or coherent sources such as lasers. Instead, it utilizes a simple light-emitting-diode (LED) and a compact opto-electronic sensor-array to record lensless holograms of the objects, which then permits rapid digital reconstruction of regular transmission or differential interference contrast (DIC) images of the objects. Because this lensless incoherent holographic microscope has orders-of-magnitude improved light collection efficiency and is very robust to mechanical misalignments it may offer a cost-effective tool especially for telemedicine applications involving various global health problems in resource limited settings.

  17. Compact, Light-weight and Cost-effective Microscope based on Lensless Incoherent Holography for Telemedicine Applications

    PubMed Central

    Mudanyali, Onur; Tseng, Derek; Oh, Chulwoo; Isikman, Serhan O.; Sencan, Ikbal; Bishara, Waheb; Oztoprak, Cetin; Seo, Sungkyu; Khademhosseini, Bahar; Ozcan, Aydogan

    2010-01-01

    Despite the rapid progress in optical imaging, most of the advanced microscopy modalities still require complex and costly set-ups that unfortunately limit their use beyond well equipped laboratories. In the meantime, microscopy in resource-limited settings has requirements significantly different from those encountered in advanced laboratories, and such imaging devices should be cost-effective, compact, light-weight and appropriately accurate and simple to be usable by minimally trained personnel. Furthermore, these portable microscopes should ideally be digitally integrated as part of a telemedicine network that connects various mobile health-care providers to a central laboratory or hospital. Toward this end, here we demonstrate a lensless on-chip microscope weighing ~46 grams with dimensions smaller than 4.2cm × 4.2cm × 5.8cm that achieves sub-cellular resolution over a large field of view of ~24 mm2. This compact and light-weight microscope is based on digital in-line holography and does not need any lenses, bulky optical/mechanical components or coherent sources such as lasers. Instead, it utilizes a simple light-emitting-diode (LED) and a compact opto-electronic sensor-array to record lensless holograms of the objects, which then permits rapid digital reconstruction of regular transmission or differential interference contrast (DIC) images of the objects. Because this lensless incoherent holographic microscope has orders-of-magnitude improved light collection efficiency and is very robust to mechanical misalignments it may offer a cost-effective tool especially for telemedicine applications involving various global health problems in resource limited settings. PMID:20401422

  18. Excavation Equipment Recognition Based on Novel Acoustic Statistical Features.

    PubMed

    Cao, Jiuwen; Wang, Wei; Wang, Jianzhong; Wang, Ruirong

    2016-09-30

    Excavation equipment recognition attracts increasing attentions in recent years due to its significance in underground pipeline network protection and civil construction management. In this paper, a novel classification algorithm based on acoustics processing is proposed for four representative excavation equipments. New acoustic statistical features, namely, the short frame energy ratio, concentration of spectrum amplitude ratio, truncated energy range, and interval of pulse are first developed to characterize acoustic signals. Then, probability density distributions of these acoustic features are analyzed and a novel classifier is presented. Experiments on real recorded acoustics of the four excavation devices are conducted to demonstrate the effectiveness of the proposed algorithm. Comparisons with two popular machine learning methods, support vector machine and extreme learning machine, combined with the popular linear prediction cepstral coefficients are provided to show the generalization capability of our method. A real surveillance system using our algorithm is developed and installed in a metro construction site for real-time recognition performance validation.

  19. Sound reduction by metamaterial-based acoustic enclosure

    SciTech Connect

    Yao, Shanshan; Li, Pei; Zhou, Xiaoming; Hu, Gengkai

    2014-12-15

    In many practical systems, acoustic radiation control on noise sources contained within a finite volume by an acoustic enclosure is of great importance, but difficult to be accomplished at low frequencies due to the enhanced acoustic-structure interaction. In this work, we propose to use acoustic metamaterials as the enclosure to efficiently reduce sound radiation at their negative-mass frequencies. Based on a circularly-shaped metamaterial model, sound radiation properties by either central or eccentric sources are analyzed by numerical simulations for structured metamaterials. The parametric analyses demonstrate that the barrier thickness, the cavity size, the source type, and the eccentricity of the source have a profound effect on the sound reduction. It is found that increasing the thickness of the metamaterial barrier is an efficient approach to achieve large sound reduction over the negative-mass frequencies. These results are helpful in designing highly efficient acoustic enclosures for blockage of sound in low frequencies.

  20. A point acoustic device based on aluminum nanowires.

    PubMed

    Xie, Qian-Yi; Ju, Zhen-Yi; Tian, He; Xue, Qing-Tang; Chen, Yuan-Quan; Tao, Lu-Qi; Mohammad, Mohammad Ali; Zhang, Xue-Yue; Yang, Yi; Ren, Tian-Ling

    2016-03-14

    A point Electrical Thermal Acoustic (ETA) device based on aluminum nanowire contacts is designed and fabricated. Interdigitated structural aluminum nanowires are released from the substrate by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE). By releasing the interdigitated structure, the nanowires contact each other at approximately 1 mm above the wafer, forming a Point Contact Structure (PCS). It is found that the PCS acoustic device realizes high efficiency when a biased AC signal is applied. The PCS acoustic device reaches a sound pressure level as high as 67 dB at a distance of 1 cm with 74 mW AC input. The power spectrum is flat, ranging from 2 kHz to 20 kHz with a less than ±3 dB fluctuation. The highest normalized Sound Pressure Level (SPL) of the point contact structure acoustic device is 18 dB higher than the suspended aluminum wire acoustic device. Comparisons between the PCS acoustic device and the Suspended Aluminum Nanowire (SAN) acoustic device illustrate that the PCS acoustic device has a flatter power spectrum within the 20 kHz range, and enhances the SPL at a lower frequency. Enhancing the response at lower frequencies is extremely useful, which may enable earphone and loudspeaker applications within the frequency range of the human ear with the help of pulse density modulation.

  1. Holography - Application To Art: Curatorial Observations

    NASA Astrophysics Data System (ADS)

    Dinsmore, Sydney

    1987-06-01

    An exploration of the need to define a specific and critical language to describe the art of holography. Within any discussion of art, critical analysis must maintain an objective openess, particularily when the discourse concerns new media. To apply technological invention to art, new media is often without precedent on which to base criticism and bias. For this reason, holography falls prey to comparative rhetoric and established evaluation of other forms of imaging,as photography emulated the compositional romanticism of painting initially. Isolated and often misunderstood within the context of history, new media vascillates between legitimacy and curiosity in an attempt to create specific parameters to identify perceptual transition.

  2. Holography inspired stringy hadrons

    NASA Astrophysics Data System (ADS)

    Sonnenschein, Jacob

    2017-01-01

    Holography inspired stringy hadrons (HISH) is a set of models that describe hadrons: mesons, baryons and glueballs as strings in flat four dimensional space-time. The models are based on a "map" from stringy hadrons of holographic confining backgrounds. In this note we review the "derivation" of the models. We start with a brief reminder of the passage from the AdS5 ×S5 string theory to certain flavored confining holographic models. We then describe the string configurations in holographic backgrounds that correspond to a Wilson line, a meson, a baryon and a glueball. The key ingredients of the four dimensional picture of hadrons are the "string endpoint mass" and the "baryonic string vertex". We determine the classical trajectories of the HISH. We review the current understanding of the quantization of the hadronic strings. We end with a summary of the comparison of the outcome of the HISH models with the PDG data about mesons and baryons. We extract the values of the tension, masses and intercepts from best fits, write down certain predictions for higher excited hadrons and present attempts to identify glueballs.

  3. Note: Vibration energy harvesting based on a round acoustic fence

    NASA Astrophysics Data System (ADS)

    Cui, Xiao-bin; Huang, Cheng-ping; Hu, Jun-hui

    2015-07-01

    An energy harvester based on a round acoustic fence (RAF) has been proposed and studied. The RAF is composed of cylindrical stubs stuck in a circular array on a thin metal plate, which can confine the acoustic energy efficiently. By removing one stub and thus opening a small gap in the RAF, acoustic leakage with larger intensity can be produced at the gap opening. With the vibration source surrounded by the RAF, the energy harvesting at the gap opening has a wide bandwidth and is insensitive to the position of the vibration source. The results may have potential applications in harvesting the energy of various vibration sources in solid structure.

  4. An acoustic filter based on layered structure.

    PubMed

    Ma, Jianguo; Steer, Michael B; Jiang, Xiaoning

    2015-03-16

    Acoustic filters (AFs) are key components to control wave propagation in multi-frequency systems. We present a design which selectively achieves acoustic filtering with a stop band and passive amplification at the high- and low-frequencies, respectively. Measurement results from the prototypes closely match the design predictions. The AF suppresses the high frequency aliasing echo by 14.5 dB and amplifies the low frequency transmission by 8.0 dB, increasing an axial resolution from 416 to 86 μm in imaging. The AF design approach is proved to be effective in multi-frequency systems.

  5. Omnidirectional broadband acoustic deflector based on metamaterials

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Liang, Bin; Zou, Xin-ye; Yang, Jing; Yang, Jun; Cheng, Jian-chun

    2017-02-01

    We report a theoretical, numerical, and experimental work on the design of an omnidirectional acoustic deflector capable of redirecting an incident wave to propagate along a predesigned direction over a broad frequency range, regardless of the incidence angle. An implementation by metamaterials is demonstrated both in simulation and experiment, with both showing the effectiveness of our scheme as long as the effective medium approximation stands. With the capability of omnidirectional broadband deflection and the flexibility of a controllable tuning angle, our design opens a route to the development of wave-steering devices and has great application potentials in various situations such as on-chip acoustic manipulations.

  6. Holography and Optical Storage

    NASA Astrophysics Data System (ADS)

    Imlau, Mirco; Fally, Martin; Burr, Geoffrey W.; Sincerbox, Glenn T.

    The term holography is composed of the Greek words holos (= whole) and graphein (= to record, to write), and thus summarizes the key aspects of its underlying principle: recording the complete wavefront of an object, i.e., its intensity as well as its phase. Interference and diffraction phenomena are employed to record and retrieve the full information, a technique pioneered by Dennis Gabor in 1948. He was honored with the Nobel prize in Physics in 1971, reflecting the general impact of holography on modern physics.

  7. Uncertainty-managed phase-shifting digital holography.

    PubMed

    Hahn, Joonku; Kim, Hwi

    2012-11-01

    Phase-shifting digital holography is a digital measurement technology of a complex optical field profile that uses focal plane array detectors without the loss of bandwidth. It has been known that the accuracy of phase-shifting digital holography is limited mainly by the phase tolerance of reference. In this Letter, it is revealed that the uncertainty in an expected signal is highly dependent on the phase of the signal itself, as well as the phase tolerance of the reference. Based on the uncertainty analysis, we propose a novel scheme of phase-shifting digital holography that exploits an uncertainty property to enhance the measurement accuracy even under significant reference phase tolerance.

  8. Reflected wavefront manipulation based on ultrathin planar acoustic metasurfaces

    PubMed Central

    Li, Yong; Liang, Bin; Gu, Zhong-ming; Zou, Xin-ye; Cheng, Jian-chun

    2013-01-01

    The introduction of metasurfaces has renewed the Snell's law and opened up new degrees of freedom to tailor the optical wavefront at will. Here, we theoretically demonstrate that the generalized Snell's law can be achieved for reflected acoustic waves based on ultrathin planar acoustic metasurfaces. The metasurfaces are constructed with eight units of a solid structure to provide discrete phase shifts covering the full 2π span with steps of π/4 by coiling up the space. By careful selection of the phase profiles in the transverse direction of the metasurfaces, some fascinating wavefront engineering phenomena are demonstrated, such as anomalous reflections, conversion of propagating waves into surface waves, planar aberration-free lens and nondiffracting Bessel beam generated by planar acoustic axicon. Our results could open up a new avenue for acoustic wavefront engineering and manipulations. PMID:23986034

  9. 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.

  10. A point acoustic device based on aluminum nanowires

    NASA Astrophysics Data System (ADS)

    Xie, Qian-Yi; Ju, Zhen-Yi; Tian, He; Xue, Qing-Tang; Chen, Yuan-Quan; Tao, Lu-Qi; Mohammad, Mohammad Ali; Zhang, Xue-Yue; Yang, Yi; Ren, Tian-Ling

    2016-03-01

    A point Electrical Thermal Acoustic (ETA) device based on aluminum nanowire contacts is designed and fabricated. Interdigitated structural aluminum nanowires are released from the substrate by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE). By releasing the interdigitated structure, the nanowires contact each other at approximately 1 mm above the wafer, forming a Point Contact Structure (PCS). It is found that the PCS acoustic device realizes high efficiency when a biased AC signal is applied. The PCS acoustic device reaches a sound pressure level as high as 67 dB at a distance of 1 cm with 74 mW AC input. The power spectrum is flat, ranging from 2 kHz to 20 kHz with a less than +/-3 dB fluctuation. The highest normalized Sound Pressure Level (SPL) of the point contact structure acoustic device is 18 dB higher than the suspended aluminum wire acoustic device. Comparisons between the PCS acoustic device and the Suspended Aluminum Nanowire (SAN) acoustic device illustrate that the PCS acoustic device has a flatter power spectrum within the 20 kHz range, and enhances the SPL at a lower frequency. Enhancing the response at lower frequencies is extremely useful, which may enable earphone and loudspeaker applications within the frequency range of the human ear with the help of pulse density modulation.A point Electrical Thermal Acoustic (ETA) device based on aluminum nanowire contacts is designed and fabricated. Interdigitated structural aluminum nanowires are released from the substrate by Inductively Coupled Plasma Reactive Ion Etching (ICP-RIE). By releasing the interdigitated structure, the nanowires contact each other at approximately 1 mm above the wafer, forming a Point Contact Structure (PCS). It is found that the PCS acoustic device realizes high efficiency when a biased AC signal is applied. The PCS acoustic device reaches a sound pressure level as high as 67 dB at a distance of 1 cm with 74 mW AC input. The power spectrum is flat, ranging from 2 k

  11. Modifying the acoustic impedance of polyurea-based composites

    NASA Astrophysics Data System (ADS)

    Nantasetphong, Wiroj; Amirkhizi, Alireza V.; Jia, Zhanzhan; Nemat-Nasser, Sia

    2013-04-01

    Acoustic impedance is a material property that depends on mass density and acoustic wave speed. An impedance mismatch between two media leads to the partial reflection of an acoustic wave sent from one medium to another. Active sonar is one example of a useful application of this phenomenon, where reflected and scattered acoustic waves enable the detection of objects. If the impedance of an object is matched to that of the surrounding medium, however, the object may be hidden from observation (at least directly) by sonar. In this study, polyurea composites are developed to facilitate such impedance matching. Polyurea is used due to its excellent blast-mitigating properties, easy casting, corrosion protection, abrasion resistance, and various uses in current military technology. Since pure polyurea has impedance higher than that of water (the current medium of interest), low mass density phenolic microballoon particles are added to create composite materials with reduced effective impedances. The volume fraction of particles is varied to study the effect of filler quantity on the acoustic impedance of the resulting composite. The composites are experimentally characterized via ultrasonic measurements. Computational models based on the method of dilute-randomly-distributed inclusions are developed and compared with the experimental results. These experiments and models will facilitate the design of new elastomeric composites with desirable acoustic impedances.

  12. Dispersion-based stimulated Raman scattering spectroscopy, holography, and optical coherence tomography

    PubMed Central

    Robles, Francisco E.; Fischer, Martin C.; Warren, Warren S.

    2016-01-01

    Stimulated Raman scattering (SRS) enables fast, high resolution imaging of chemical constituents important to biological structures and functional processes, both in a label-free manner and using exogenous biomarkers. While this technology has shown remarkable potential, it is currently limited to point scanning and can only probe a few Raman bands at a time (most often, only one). In this work we take a fundamentally different approach to detecting the small nonlinear signals based on dispersion effects that accompany the loss/gain processes in SRS. In this proof of concept, we demonstrate that the dispersive measurements are more robust to noise compared to amplitude-based measurements, which then permit spectral or spatial multiplexing (potentially both, simultaneously). Finally, we illustrate how this method may enable different strategies for biochemical imaging using phase microscopy and optical coherence tomography. PMID:26832279

  13. Fiber-based lensless polarization holography for measuring Jones matrix parameters of polarization-sensitive materials.

    PubMed

    Liu, Xuan; Yang, Yang; Han, Lu; Guo, Cheng-Shan

    2017-04-03

    We report a fiber-based lensless holographic imaging system to realize a single-shot measurement of two dimensional (2-D) Jones matrix parameters of polarization-sensitive materials. In this system, a multi-source lensless off-axis Fresnel holographic recording geometry is adopted, and two optical fiber splitters are used to generate the multiple reference and illumination beams required for recording a four-channel angular-multiplexing polarization hologram (AMPH). Using this system and the method described in this paper, spatially resolved Jones matrix parameters of a polarization-sensitive material can be retrieved from one single-shot AMPH. We demonstrate the feasibility of the method by extracting a 2-D Jones matrix of a composite polarizer. Applications of the method to measure the Jones matrix maps of a stressed polymethyl methacrylate sample and a mica fragment are also presented. Benefit from the fiber-based and lensless off-axis holographic design, the system possesses a quite compact configuration, which provides a feasible approach for development of an integrated and portable system to measure Jones matrix parameters of polarization-sensitive materials.

  14. Drying process in a solvent-based paint analyzed by phase-shifting digital holography and an estimation of time for tack free.

    PubMed

    Yokota, Masayuki; Kawakami, Tomoaki; Kimoto, Yoshiki; Yamaguchi, Ichirou

    2011-10-20

    A technique to study the drying of paints, based on phase-shifting digital holography, is presented. The technique is applied to the drying process of solvent-based paint on a three-dimensional surface at different substrate temperatures. For processing the data, a cross-correlation function and phase change derived from reconstructed complex amplitudes are calculated to visualize and to evaluate the local variations in the dryness of paint. The relationship between the optical signal obtained by the holographic method and the actual microscopic variations occurring in the paint film is also investigated using the gravimetric technique and a microscope. It is shown that the holographic technique can determine the stationary state of a painted surface corresponding to the end of the falling rate period in the drying process. The holographic technique detects mainly the activity on the surface and is applicable to assessment of the early drying process of paint.

  15. Incoherent digital holography with phase-only spatial light modulators

    NASA Astrophysics Data System (ADS)

    Rosen, Joseph; Kelner, Roy; Kashter, Yuval

    2015-10-01

    Today, spatial light modulators (SLMs) offer the world of digital holography a robust technology that can be incorporated into hologram recorders. This review surveys recent developments related to the role of SLMs in a family of incoherent digital hologram recorders termed Fresnel incoherent correlation holography (FINCH). Two systems branching out from FINCH, and discussed herein, are a confocal version of FINCH and a synthetic aperture FINCH-based system.

  16. Electro-holography display using computer generated hologram of 3D objects based on projection spectra

    NASA Astrophysics Data System (ADS)

    Huang, Sujuan; Wang, Duocheng; He, Chao

    2012-11-01

    A new method of synthesizing computer-generated hologram of three-dimensional (3D) objects is proposed from their projection images. A series of projection images of 3D objects are recorded with one-dimensional azimuth scanning. According to the principles of paraboloid of revolution in 3D Fourier space and 3D central slice theorem, spectra information of 3D objects can be gathered from their projection images. Considering quantization error of horizontal and vertical directions, the spectrum information from each projection image is efficiently extracted in double circle and four circles shape, to enhance the utilization of projection spectra. Then spectra information of 3D objects from all projection images is encoded into computer-generated hologram based on Fourier transform using conjugate-symmetric extension. The hologram includes 3D information of objects. Experimental results for numerical reconstruction of the CGH at different distance validate the proposed methods and show its good performance. Electro-holographic reconstruction can be realized by using an electronic addressing reflective liquid-crystal display (LCD) spatial light modulator. The CGH from the computer is loaded onto the LCD. By illuminating a reference light from a laser source to the LCD, the amplitude and phase information included in the CGH will be reconstructed due to the diffraction of the light modulated by the LCD.

  17. A surface-acoustic-wave-based cantilever bio-sensor.

    PubMed

    De Simoni, Giorgio; Signore, Giovanni; Agostini, Matteo; Beltram, Fabio; Piazza, Vincenzo

    2015-06-15

    A scalable surface-acoustic-wave- (SAW-) based cantilevered device for portable bio-chemical sensing applications is presented. Even in the current, proof-of-principle implementation this architecture is shown to outperform commercial quartz-crystal microbalances in terms of sensitivity. Adhesion of analytes on a functionalized surface of the cantilever shifts the resonant frequency of a SAW-generating transducer due to the stress-induced variation of the speed of surface acoustic modes. We discuss the relevance of this approach for diagnostics applications based on miniaturized devices.

  18. High-speed broadband slight-off digital holography based on simultaneous two-step Gouy phase shifting interferometry

    NASA Astrophysics Data System (ADS)

    Lu, Xiaowei; Xu, Shixiang; Li, Jingzhen; Cai, Yi; Fan, Yupeng

    2016-02-01

    It is well known that phase shift is depended on wavelength of light source by traditional optical path difference (OPD) in free space or wave plate methods. In this paper, we demonstrated a slight-off two-step Gouy phase shifting interferometry which is suitable for broadband digital holography. This technique uses Gouy phase shift to introduce π phase differences between two reference arms. A dual-channel interferometer was employed to monitor the Gouy phase-shifting between two orthogonal polarized references and snap imaging with single shot enabling potential real-time and high-speed imaging capabilities. Theoretical analysis and numerical simulation comparisons between the proposed method and some traditional phase shifting approaches for broadband digital holography were given. Accurate recovers can be obtained in ideal conditions by Gouy, OPD in free space and λ/2 wave plate methods. However, when considering of environment influence, the accuracy of the traditional methods declined rapidly, the recover errors are more than 70 and 20 times higher than our proposed method. The results also show that Gouy method can get consistent phase shift for broadband light source with little influence with wavelength.

  19. Standing surface acoustic wave (SSAW)-based cell washing

    PubMed Central

    Li, Sixing; Ding, Xiaoyun; Mao, Zhangming; Chen, Yuchao; Nama, Nitesh; Guo, Feng; Li, Peng; Wang, Lin; Cameron, Craig E.; Huang, Tony Jun

    2014-01-01

    Cell/bead washing is an indispensable sample preparation procedure used in various cell studies and analytical processes. In this article, we report a standing surface acoustic wave (SSAW)-based microfluidic device for cell and bead washing in a continuous flow. In our approach, the acoustic radiation force generated in a SSAW field is utilized to actively extract cells or beads from their original medium. A unique configuration of tilted-angle standing surface acoustic wave (taSSAW) is employed in our device, enabling us to wash beads with >98% recovery rate and >97% washing efficiency. We also demonstrate the functionality of our device by preparing high-purity (>97%) white blood cells from lysed blood samples through cell washing. Our SSAW-based cell/bead washing device has the advantages of label-free manipulation, simplicity, high biocompatibility, high recovery rate, and high washing efficiency. It can be useful for many lab-on-a-chip applications. PMID:25372273

  20. Investigation of (Fe,Co)NbB-Based Nanocrystalline Soft Magnetic Alloys by Lorentz Microscopy and Off-Axis Electron Holography.

    PubMed

    Zheng, Changlin; Kirmse, Holm; Long, Jianguo; Laughlin, David E; McHenry, Michael E; Neumann, Wolfgang

    2015-04-01

    The relationship between microstructure and magnetic properties of a (Fe,Co)NbB-based nanocrystalline soft magnetic alloy was investigated by analytical transmission electron microscopy (TEM). The microstructures of (Fe0.5Co0.5)80Nb4B13Ge2Cu1 nanocrystalline alloys annealed at different temperatures were characterized by TEM and electron diffraction. The magnetic structures were analyzed by Lorentz microscopy and off-axis electron holography, including quantitative measurement of domain wall width, induction, and in situ magnetic domain imaging. The results indicate that the magnetic domain structure and particularly the dynamical magnetization behavior of the alloys strongly depend on the microstructure of the nanocrystalline alloys. Smaller grain size and random orientation of the fine particles decrease the magneto-crystalline anisotropy and suggests better soft magnetic properties which may be explained by the anisotropy model of Herzer.

  1. Holography: science and art

    NASA Astrophysics Data System (ADS)

    Boone, Pierre M.

    1998-09-01

    Art and science are separated by a very large distance nowadays. Long ago, e.g. in Renaissance, or even earlier, in classic Greece and Rome, or still earlier in Egypt or Mesopotamia, arts and sciences were united. Today they seem to go separate paths: science for the industry, arts for the gallery. Holography is an exception: no art without science, but also no science without art.

  2. Dynamic holography using pixelated light modulators.

    PubMed

    Zwick, Susanne; Haist, Tobias; Warber, Michael; Osten, Wolfgang

    2010-09-01

    Dynamic holography using spatial light modulators is a very flexible technique that offers various new applications compared to static holography. We give an overview on the technical background of dynamic holography focusing on pixelated spatial light modulators and their technical restrictions, and we present a selection of the numerous applications of dynamic holography.

  3. Performance Evaluation of a Biometric System Based on Acoustic Images

    PubMed Central

    Izquierdo-Fuente, Alberto; del Val, Lara; Jiménez, María I.; Villacorta, Juan J.

    2011-01-01

    An acoustic electronic scanning array for acquiring images from a person using a biometric application is developed. Based on pulse-echo techniques, multifrequency acoustic images are obtained for a set of positions of a person (front, front with arms outstretched, back and side). Two Uniform Linear Arrays (ULA) with 15 λ/2-equispaced sensors have been employed, using different spatial apertures in order to reduce sidelobe levels. Working frequencies have been designed on the basis of the main lobe width, the grating lobe levels and the frequency responses of people and sensors. For a case-study with 10 people, the acoustic profiles, formed by all images acquired, are evaluated and compared in a mean square error sense. Finally, system performance, using False Match Rate (FMR)/False Non-Match Rate (FNMR) parameters and the Receiver Operating Characteristic (ROC) curve, is evaluated. On the basis of the obtained results, this system could be used for biometric applications. PMID:22163708

  4. Acoustic waves switch based on meta-fluid phononic crystals

    NASA Astrophysics Data System (ADS)

    Zhu, Xue-Feng

    2012-08-01

    The acoustic waves switch based on meta-fluid phononic crystals (MEFL PCs) is theoretically investigated. The MEFL PCs consist of fluid matrix and fluid-like inclusions with extremely anisotropic-density. The dispersion relations are calculated via the plane wave expansion method, which are in good agreement with the transmitted sound pressure level spectra obtained by the finite element method. The results show that the width of absolute band gap in MEFL PCs depends sensitively upon the orientation of the extremely anisotropic-density inclusions and reaches maximum at the rotating angle of 45°, with the gap position nearly unchanged. Also, the inter-mode conversion inside anisotropic-density inclusions can be ignored due to large acoustic mismatch. The study gives a possibility to realize greater flexibility and stronger effects in tuning the acoustic band gaps, which is very significant in the enhanced control over sound waves and has potential applications in ultrasonic imaging and therapy.

  5. Acoustic carpet cloak based on an ultrathin metasurface

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    An acoustic metasurface carpet cloak based on membrane-capped cavities is proposed and investigated numerically. This design has been chosen for allowing ultrathin geometries, although adapted to airborne sound frequencies in the range of 1 kHz (λ ≈30 cm), surpassing the designs reported in the literature in terms of thinness. A formulation of generalized Snell's laws is first proposed, mapping the directions of the incident and reflected waves to the metasurface phase function. This relation is then applied to achieve a prescribed wavefront reflection direction, for a given incident direction, by controlling the acoustic impedance grading along the metasurface. The carpet cloak performance of the proposed acoustic metasurface is then assessed on a triangular bump obstacle, generally considered as a baseline configuration in the literature.

  6. An invisible acoustic sensor based on parity-time symmetry

    NASA Astrophysics Data System (ADS)

    Fleury, Romain; Sounas, Dimitrios; Alù, Andrea

    2015-01-01

    Sensing an incoming signal is typically associated with absorbing a portion of its energy, inherently perturbing the measurement and creating reflections and shadows. Here, in contrast, we demonstrate a non-invasive, shadow-free, invisible sensor for airborne sound waves at audible frequencies, which fully absorbs the impinging signal, without at the same time perturbing its own measurement or creating a shadow. This unique sensing device is based on the unusual scattering properties of a parity-time (PT) symmetric metamaterial device formed by a pair of electro-acoustic resonators loaded with suitably tailored non-Foster electrical circuits, constituting the acoustic equivalent of a coherent perfect absorber coupled to a coherent laser. Beyond the specific application to non-invasive sensing, our work broadly demonstrates the unique relevance of PT-symmetric metamaterials for acoustics, loss compensation and extraordinary wave manipulation.

  7. An invisible acoustic sensor based on parity-time symmetry.

    PubMed

    Fleury, Romain; Sounas, Dimitrios; Alù, Andrea

    2015-01-06

    Sensing an incoming signal is typically associated with absorbing a portion of its energy, inherently perturbing the measurement and creating reflections and shadows. Here, in contrast, we demonstrate a non-invasive, shadow-free, invisible sensor for airborne sound waves at audible frequencies, which fully absorbs the impinging signal, without at the same time perturbing its own measurement or creating a shadow. This unique sensing device is based on the unusual scattering properties of a parity-time (PT) symmetric metamaterial device formed by a pair of electro-acoustic resonators loaded with suitably tailored non-Foster electrical circuits, constituting the acoustic equivalent of a coherent perfect absorber coupled to a coherent laser. Beyond the specific application to non-invasive sensing, our work broadly demonstrates the unique relevance of PT-symmetric metamaterials for acoustics, loss compensation and extraordinary wave manipulation.

  8. Gasoline identifier based on SH0 plate acoustic waves.

    PubMed

    Kuznetsova, Iren E; Zaitsev, Boris D; Seleznev, Eugenii P; Verona, Enrico

    2016-08-01

    The present paper is devoted to the development of gasoline identifier based on zero order shear-horizontal (SH0) acoustic wave propagating in piezoelectric plate. It has been found that the permittivity of gasoline is increased when its octane number rises. The development of such identifier is experimentally demonstrated to be possible.

  9. Holography in the Junior High.

    ERIC Educational Resources Information Center

    Tomaszkiewicz, Frank

    1988-01-01

    Examines the use of holography in the art technology program of a junior high school. Characterizing holography as a valuable artistic experience and discovery experience and stressing the importance of student interest and involvement, the author discusses the necessary equipment for the project and includes two diagrams of a holographic setup.…

  10. Acoustic Intensity Measurements in the Presence of Low Mach Number Flow

    DTIC Science & Technology

    1993-09-01

    broadband acoustic holography ,3 intensity measurements in the presence of flow,"𔄁𔄀. 7 in-situ evaluation of the acoustic impedance and sound absorption...Cross Spectra" Ph.D. Thesis, Catholic University, (1987). 3. Loyau, T., Pascal, J., Gaillard, P., "Broadband Acoustic Holography Reconstruction From...AD-A269 995 The Pennsylvania State University APPLIED RESEARCH LABORATORY P.O. Box 30 State College, PA 16804 ACOUSTIC INTENSITY MEASUREMENTS IN THE

  11. Development of complex 3D microstructures based on computer generated holography and their usage for biomedical applications

    NASA Astrophysics Data System (ADS)

    Palevicius, Arvydas; Grigaliunas, Viktoras; Janusas, Giedrius; Palevicius, Paulius; Sakalys, Rokas

    2016-04-01

    The main focus of the paper is the development of technological route of the production of complex 3D microstructure, from designing it by the method of computer generated holography till its physical 3D patterning by exploiting the process of electron beam lithography and thermal replication which is used for biomedical application. A phase data of a complex 3D microstructure was generated by using Gerchberg-Saxton algorithm which later was used to produce a computer generated hologram. Physical implementation of microstructure was done using a single layer polymethyl methacrylate (PMMA) as a basis for 3D microstructure, which was exposed using e-beam lithography system e-Line and replicated, using high frequency vibration. Manufactured 3D microstructure is used for designing micro sensor for biomedical applications.

  12. Generalized phase-shifting color digital holography

    NASA Astrophysics Data System (ADS)

    Nomura, Takanori; Kawakami, Takaaki; Shinomura, Kazuma

    2016-06-01

    Two methods to apply the generalized phase-shifting digital holography to color digital holography are proposed. One is wave-splitting generalized phase-shifting color digital holography. This is realized by using a color Bayer camera. Another is multiple exposure generalized phase-shifting color digital holography. This is realized by the wavelength-dependent phase-shifting devices. Experimental results for both generalized phase-shifting color digital holography are presented to confirm the proposed methods.

  13. White Light Holography Using Flexible Membrane Mirrors

    NASA Astrophysics Data System (ADS)

    Warren, D.; King, W.; Waddell, P.; Raptodimos, T.

    1988-06-01

    White light transmission holograms have been made using revolutionary flexible membrane concave mirrors of variable focal length. These mirrors are used as collimators to produce and project conjugate imagery for making white light holograms. The era of super large scale white light holography with undistorted imagery and large angular field of view is predicted, based on current results and the availability of very wide plastic sheets suitable for use as the reflective membrane of the flexible mirrors.

  14. Adaptive Optical Scanning Holography

    PubMed Central

    Tsang, P. W. M.; Poon, Ting-Chung; Liu, J.-P.

    2016-01-01

    Optical Scanning Holography (OSH) is a powerful technique that employs a single-pixel sensor and a row-by-row scanning mechanism to capture the hologram of a wide-view, three-dimensional object. However, the time required to acquire a hologram with OSH is rather lengthy. In this paper, we propose an enhanced framework, which is referred to as Adaptive OSH (AOSH), to shorten the holographic recording process. We have demonstrated that the AOSH method is capable of decreasing the acquisition time by up to an order of magnitude, while preserving the content of the hologram favorably. PMID:26916866

  15. Femtosecond spectral holography

    NASA Astrophysics Data System (ADS)

    Weiner, Andrew M.; Leaird, Daniel E.; Reitze, David H.; Paek, Eung G.

    1992-10-01

    Storage, recall, and processing of shaped femtosecond waveforms are achieved by performing spectral holography within a femtosecond pulse shaping apparatus. Time reversal, as well as correlation and convolution, of femtosecond temporal signals is demonstrated. Applications of this technique to matched filtering, dispersion compensation, encryption and decoding, and femtosecond waveform synthesis are also discussed. The work extends the powerful principles of holographic signal processing, which have been used extensively for pattern recognition and filtering of two-dimensional spatial signals, to the femtosecond time domain.

  16. Femtosecond spectral holography

    SciTech Connect

    Weiner, A.M.; Leaird, D.E.; Reitze, D.H.; Paek, E.G. )

    1992-10-01

    Storage, recall, and processing of shaped femtosecond waveforms are achieved by performing spectral holography within a femtosecond pulse shaping apparatus. Time reversal, as well as correlation and convolution, of femtosecond temporal signals is demonstrated. Applications of this technique to matched filtering, dispersion compensation, encryption and decoding, and femtosecond waveform synthesis are also discussed. The work extends the powerful principles of holographic signal processing, which have been used extensively for pattern recognition and filtering of two-dimensional spatial signals, to the femtosecond time domain. 44 refs.

  17. Adaptive Optical Scanning Holography

    NASA Astrophysics Data System (ADS)

    Tsang, P. W. M.; Poon, Ting-Chung; Liu, J.-P.

    2016-02-01

    Optical Scanning Holography (OSH) is a powerful technique that employs a single-pixel sensor and a row-by-row scanning mechanism to capture the hologram of a wide-view, three-dimensional object. However, the time required to acquire a hologram with OSH is rather lengthy. In this paper, we propose an enhanced framework, which is referred to as Adaptive OSH (AOSH), to shorten the holographic recording process. We have demonstrated that the AOSH method is capable of decreasing the acquisition time by up to an order of magnitude, while preserving the content of the hologram favorably.

  18. Holography gets smart

    NASA Astrophysics Data System (ADS)

    Lowe, Chris; Larbey, Cynthia

    2008-02-01

    At least 6% of world trade, amounting to some 200bn per year, involves counterfeit goods. But this figure would be even higher were it not for the humble hologram. Invented 50 years ago, holograms provide authentication tags to deter copying, and can be found everywhere from credit cards, passports and banknotes to consumer goods, cosmetics and pharmaceuticals. Holography also underpins supermarket scanners and CD players; it can even be used to store optical data in 3D. Now, however, holograms are making their mark as powerful yet cheap diagnostic tools, which could in particular have many applications in biomedicine.

  19. Talbot self-image effect in digital holography and its application to spectrometry.

    PubMed

    De Nicola, Sergio; Ferraro, Pietro; Coppola, Giuseppe; Finizio, Andrea; Pierattini, Giovanni; Grilli, Simonetta

    2004-01-01

    For the first time to the authors' knowledge, the Talbot effect has been observed and investigated in digital holography. By numerical reconstruction of holograms, the Talbot self-imaging phenomenon is observed by reconstruction of the amplitude of the image at different distances and (or) wavelengths. A simple spectrometer based on Talbot self-imaging in digital holography is proposed and demonstrated.

  20. Split-illumination electron holography

    SciTech Connect

    Tanigaki, Toshiaki; Aizawa, Shinji; Suzuki, Takahiro; Park, Hyun Soon; Inada, Yoshikatsu; Matsuda, Tsuyoshi; Taniyama, Akira; Shindo, Daisuke; Tonomura, Akira

    2012-07-23

    We developed a split-illumination electron holography that uses an electron biprism in the illuminating system and two biprisms (applicable to one biprism) in the imaging system, enabling holographic interference micrographs of regions far from the sample edge to be obtained. Using a condenser biprism, we split an electron wave into two coherent electron waves: one wave is to illuminate an observation area far from the sample edge in the sample plane and the other wave to pass through a vacuum space outside the sample. The split-illumination holography has the potential to greatly expand the breadth of applications of electron holography.

  1. Acoustic superlens using Helmholtz-resonator-based metamaterials

    NASA Astrophysics Data System (ADS)

    Yang, Xishan; Yin, Jing; Yu, Gaokun; Peng, Linhui; Wang, Ning

    2015-11-01

    Acoustic superlens provides a way to overcome the diffraction limit with respect to the wavelength of the bulk wave in air. However, the operating frequency range of subwavelength imaging is quite narrow. Here, an acoustic superlens is designed using Helmholtz-resonator-based metamaterials to broaden the bandwidth of super-resolution. An experiment is carried out to verify subwavelength imaging of double slits, the imaging of which can be well resolved in the frequency range from 570 to 650 Hz. Different from previous works based on the Fabry-Pérot resonance, the corresponding mechanism of subwavelength imaging is the Fano resonance, and the strong coupling between the neighbouring Helmholtz resonators separated at the subwavelength interval leads to the enhanced sound transmission over a relatively wide frequency range.

  2. Acoustic superlens using Helmholtz-resonator-based metamaterials

    SciTech Connect

    Yang, Xishan; Yin, Jing; Yu, Gaokun Peng, Linhui; Wang, Ning

    2015-11-09

    Acoustic superlens provides a way to overcome the diffraction limit with respect to the wavelength of the bulk wave in air. However, the operating frequency range of subwavelength imaging is quite narrow. Here, an acoustic superlens is designed using Helmholtz-resonator-based metamaterials to broaden the bandwidth of super-resolution. An experiment is carried out to verify subwavelength imaging of double slits, the imaging of which can be well resolved in the frequency range from 570 to 650 Hz. Different from previous works based on the Fabry-Pérot resonance, the corresponding mechanism of subwavelength imaging is the Fano resonance, and the strong coupling between the neighbouring Helmholtz resonators separated at the subwavelength interval leads to the enhanced sound transmission over a relatively wide frequency range.

  3. Pre-holography

    SciTech Connect

    Kay, Bernard S.; Larkin, Peter

    2008-06-15

    We construct a symplectic isomorphism h from classical Klein Gordon solutions of mass m on (d+1)-dimensional Lorentzian anti-de Sitter space (equipped with the usual symplectic form) to a certain symplectic space of functions on its conformal boundary (only) for all integer and half-integer {delta} (=(d/2)+(1/2)(d{sup 2}+4m{sup 2}){sup 1/2}). h induces a large family of new examples of Rehren's algebraic holography in which the net of local quantum Klein Gordon algebras in AdS is seen to map to a suitably defined net of local algebras for the (generalized free) scalar conformal field with anomalous dimension {delta} on d-dimensional Minkowski space (the AdS boundary). Relatedly, we show for these models that Bertola et al.'s boundary-limit holography becomes a quantum duality (only) if the test functions for boundary Wightman distributions are restricted in a particular way.

  4. Tailoring ultrasonic beams with optoacoustic holography

    NASA Astrophysics Data System (ADS)

    Meyer, Alex; Gspan, Stefan J.; Bernet, Stefan; Ritsch-Marte, Monika

    2003-06-01

    A combination of laser-induced ultrasound generation and ultrasonic holography for spatial control of the generated ultrasonic pulse is presented. Ultrasound is produced by absorption of laser pulses at an absorbing layer in a water tank via the optoacoustic effect. In order to produce a defined ultrasonic frequency in the MHz range, the laser pulses are harmonically time-modulated using an acousto-optic modulator (AOM). Additionally, the laser intensity is spatially controlled. This is realized with a high resolution liquid crystal spatial light modulator (LCD). A computer generated pattern is displayed at the LCD and projected by the expanded laser beam to an absorptive layer in the water tank. As a result, the emitted ultrasonic wave emerges in a predetermined way, which is an acoustical analogue to the effect of a "diffractive optical element" in laser optics. The flexible method of optical ultrasound generation and diffractive steering promises new applications in medical and technical ultrasound diagnostics.

  5. Acoustic wave filter based on periodically poled lithium niobate.

    PubMed

    Courjon, Emilie; Bassignot, Florent; Ulliac, Gwenn; Benchabane, Sarah; Ballandras, Sylvain

    2012-09-01

    Solutions for the development of compact RF passive transducers as an alternative to standard surface or bulk acoustic wave devices are receiving increasing interest. This article presents results on the development of an acoustic band-pass filter based on periodically poled ferroelectric domains in lithium niobate. The fabrication of periodically poled transducers (PPTs) operating in the range of 20 to 650 MHz has been achieved on 3-in (76.2-mm) 500-μm-thick wafers. This kind of transducer is able to excite elliptical as well as longitudinal modes, yielding phase velocities of about 3800 and 6500 ms(-1), respectively. A new type of acoustic band-pass filter is proposed, based on the use of PPTs instead of the SAWs excited by classical interdigital transducers. The design and the fabrication of such a filter are presented, as well as experimental measurements of its electrical response and transfer function. The feasibility of such a PPT-based filter is thereby demonstrated and the limitations of this method are discussed.

  6. Atomic resolution holography.

    PubMed

    Hayashi, Kouichi

    2014-11-01

    Atomic resolution holography, such as X-ray fluorescence holography (XFH)[1] and photoelectron holography (PH), has the attention of researcher as an informative local structure analysis, because it provides three dimensional atomic images around specific elements within a range of a few nanometers. It can determine atomic arrangements around a specific element without any prior knowledge of structures. It is considered that the atomic resolution holographic is a third method of structural analysis at the atomic level after X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS). As known by many researchers, XRD and XAFS are established methods that are widespread use in various fields. XRD and XAFS provide information on long-range translational periodicities and very local environments, respectively, whereas the atomic resolution holography gives 3D information on the local order and can visualize surrounding atoms with a large range of coordination shells. We call this feature "3D medium-range local structure observation".In addition to this feature, the atomic resolution holography is very sensitive to the displacement of atoms from their ideal positions, and one can obtain quantitative information about local lattice distortions by analyzing reconstructed atomic images[2] When dopants with different atomic radii from the matrix elements are present, the lattices around the dopants are distorted. However, using the conventional methods of structural analysis, one cannot determine the extent to which the local lattice distortions are preserved from the dopants. XFH is a good tool for solving this problem.Figure 1 shows a recent achievement on a relaxor ferroelectric of Pb(Mg1/3Nb2/3)O3 (PMN) using XFH. The structural studies of relaxor ferroelectrics have been carried out by X-ray or neutron diffractions, which suggested rhombohedral distortions of their lattices. However, their true pictures have not been obtained, yet. The Nb Kα holograms showed

  7. The acoustic spectrophonometer: a novel bioanalytical technique based on multifrequency acoustic devices.

    PubMed

    Stevenson, A C; Araya-Kleinsteuber, B; Sethi, R S; Mehta, H M; Lowe, C R

    2003-10-01

    A measurement technique similar to optical absorption spectroscopy but based on evanescent acoustic waves is described in this paper. This format employs a planar spiral coil to vibrate a single crystal of quartz from 6 to 400 MHz, in order to measure multifrequency acoustic spectra. Consistency with the defined Sauerbrey and Kanazawa terms K1 and K2 when applied to multiple frequencies was found for these specific operating conditions in terms of a significant fit between the measured and calculated values: For an IgG surface density of 13.5 ng mm(-2) the measured value of K1 is 22.5 x 10(-6) and the calculated value is 20.4 x 10(-6), whilst for glycerol viscous loadings of 5.131 cP the measured value of K2 is 0.47 and the calculated value is 0.54. Thus for these specific surface loadings the multifrequency data fits to the predictions of the Sauerbrey model to within 10% and to Kanazawa model within 13%. However collective frequency shifts for 5.131 cP solutions of sucrose, dextran and glucose were found to exhibit an unanticipated additional variability (R2 < 0.4) with frequency, but retained a square root of frequency dependency within a factor 2 of the interpolated K2 values. The response to the 5.131 cP dextran solution was found to be significantly below the other isoviscous solutions, with a substantially reduced frequency shift and K2 value than would be expected from its bulk viscosity. In comparison with these viscous solutions, IgG protein films consistently produced linear frequency shifts with little scatter (R2 > 0.96) that were proportional to the operating frequency, and fully consistent with the Sauerbrey model under these specific conditions. A t-test value of 14.52 was calculated from the variance and mean of the two groups, and demonstrates that the acoustic spectrophonometer can be used to distinguish between the acoustic impedance characteristics of two chemical systems that are not clearly differentiable at a single operating frequency.

  8. Ultrarealistic imaging: the future of display holography

    NASA Astrophysics Data System (ADS)

    Bjelkhagen, Hans I.; Brotherton-Ratcliffe, David

    2014-11-01

    Ultrarealistic imaging is the science of producing images that faithfully recreate the light field surrounding an object, such that the unaided eye of a human observer cannot distinguish the difference between the original and the image. Recent technology improvements are now set to transform the fields of both analog and digital display holography, permitting both techniques to operate in the ultrarealistic regime. In particular, ultrarealistic analog holograms have now heralded the serious use of holography in such areas as museum display and cultural heritage protection. These full-color holograms are characterized by a substantially lower noise and a greater spectral fidelity. New recording systems, based on recent diode-pumped solid-state and semiconductor lasers combined with recording materials and processing, have been behind these improvements. Progress in illumination technology, however, has also led to a major reduction in display noise and to a significant increase in the clear image depth and brightness of holograms. Recent progress in one-step direct-write digital holography (DWDH) is now also opening the way to the creation of a new type of ultrarealistic display: the high virtual volume display. This is a large format full-parallax DWDH reflection hologram having a fundamentally larger clear image depth.

  9. Multispectral photoacoustic microscopy based on an optical–acoustic objective

    PubMed Central

    Cao, Rui; Kilroy, Joseph P.; Ning, Bo; Wang, Tianxiong; Hossack, John A.; Hu, Song

    2015-01-01

    We have developed reflection-mode multispectral photoacoustic microscopy (PAM) based on a novel optical–acoustic objective that integrates a customized ultrasonic transducer and a commercial reflective microscope objective into one solid piece. This technical innovation provides zero chromatic aberration and convenient confocal alignment of the optical excitation and acoustic detection. With a wavelength-tunable optical-parametric-oscillator laser, we have demonstrated multispectral PAM over an ultrabroad spectral range of 270–1300 nm. A near-constant lateral resolution of ∼2.8 μm is achieved experimentally. Capitalizing on the consistent performance over the ultraviolet, visible, and near-infrared range, multispectral PAM enables label-free concurrent imaging of cell nucleus (DNA/RNA contrast at 270 nm), blood vessel (hemoglobin contrast at 532 nm), and sebaceous gland (lipid contrast at 1260 nm) at the same spatial scale in a living mouse ear. PMID:26236641

  10. Multispectral photoacoustic microscopy based on an optical-acoustic objective.

    PubMed

    Cao, Rui; Kilroy, Joseph P; Ning, Bo; Wang, Tianxiong; Hossack, John A; Hu, Song

    2015-06-01

    We have developed reflection-mode multispectral photoacoustic microscopy (PAM) based on a novel optical-acoustic objective that integrates a customized ultrasonic transducer and a commercial reflective microscope objective into one solid piece. This technical innovation provides zero chromatic aberration and convenient confocal alignment of the optical excitation and acoustic detection. With a wavelength-tunable optical-parametric-oscillator laser, we have demonstrated multispectral PAM over an ultrabroad spectral range of 270-1300 nm. A near-constant lateral resolution of ∼2.8 μm is achieved experimentally. Capitalizing on the consistent performance over the ultraviolet, visible, and near-infrared range, multispectral PAM enables label-free concurrent imaging of cell nucleus (DNA/RNA contrast at 270 nm), blood vessel (hemoglobin contrast at 532 nm), and sebaceous gland (lipid contrast at 1260 nm) at the same spatial scale in a living mouse ear.

  11. Understanding Piezo Based Sensors for Acoustic Neutrino Detection

    NASA Astrophysics Data System (ADS)

    Naumann, C. L.; Anton, G.; Graf, K.; Höβl, J.; Kappes, A.; Katz, U. F.; Lahmann, R.; Salomon, K.

    2007-09-01

    The ANTARES collaboration is currently installing a neutrino telescope off the French Mediterranean coast to measure diffuse fluxes and point sources of high energy cosmic neutrinos. The complete detector will consist of 900 photomultipliers on 12 detector lines, using 0.01km3 of sea water as target material[1]. As part of the ANTARES deep-sea research infrastructure, the Erlangen group is planning to modify several ANTARES storeys by fitting them with acoustic receivers to study the feasibility of acoustic neutrino detection in the deep sea. In this paper, studies of the electromechanical properties of piezoelectric sensors are presented, based on an equivalent circuit diagram for the coupled mechanical and electrical oscillations of a piezoelectric element. A method for obtaining the system parameters as well as derivations of sensor properties like pressure sensitivity and intrinsic noise are treated and results compared to measurements. Finally, a possible application of these results for simulating system response and optimising reconstruction algorithms is discussed.

  12. Compensation algorithm for the phase-shift error of polarization-based parallel two-step phase-shifting digital holography.

    PubMed

    Tahara, Tatsuki; Ito, Kenichi; Kakue, Takashi; Fujii, Motofumi; Shimozato, Yuki; Awatsuji, Yasuhiro; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2011-03-01

    We propose an algorithm for compensating the phase-shift error of polarization-based parallel two-step phase-shifting digital holography, which is a technique for recording a spatial two-step phase-shifted hologram. Although a polarization-based system of the technique has been experimentally demonstrated, there had been the problem that the phase difference of two phase-shifted holograms had been changed by the extinction ratio of the micropolarizer array attached to the image sensor used in the system. To improve the performance of the system, we established and formulated an algorithm for compensating the phase-shift error. Accurate spatial phase-shifting interferometry in the system can be conducted by the algorithm regardless of phase-shift error due to the extinction ratio. By the numerical simulation, the proposed algorithm was capable of reducing the root mean square errors of the reconstructed image by 1/4 and 1/5 in amplitude and phase, respectively. Also, the algorithm was experimentally demonstrated, and the experimental results showed that the system employing the proposed algorithm suppressed the conjugate image, which slightly appeared in the image reconstructed by the system not employing the algorithm, even when the extinction ratio was 10:1. Thus, the effectiveness of the proposed algorithm was numerically and experimentally verified.

  13. Acoustic asymmetric transmission based on time-dependent dynamical scattering

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Yang, Yang; Ni, Xu; Xu, Ye-Long; Sun, Xiao-Chen; Chen, Ze-Guo; Feng, Liang; Liu, Xiao-Ping; Lu, Ming-Hui; Chen, Yan-Feng

    2015-06-01

    An acoustic asymmetric transmission device exhibiting unidirectional transmission property for acoustic waves is extremely desirable in many practical scenarios. Such a unique property may be realized in various configurations utilizing acoustic Zeeman effects in moving media as well as frequency-conversion in passive nonlinear acoustic systems and in active acoustic systems. Here we demonstrate a new acoustic frequency conversion process in a time-varying system, consisting of a rotating blade and the surrounding air. The scattered acoustic waves from this time-varying system experience frequency shifts, which are linearly dependent on the blade’s rotating frequency. Such scattering mechanism can be well described theoretically by an acoustic linear time-varying perturbation theory. Combining such time-varying scattering effects with highly efficient acoustic filtering, we successfully develop a tunable acoustic unidirectional device with 20 dB power transmission contrast ratio between two counter propagation directions at audible frequencies.

  14. Acoustic asymmetric transmission based on time-dependent dynamical scattering

    PubMed Central

    Wang, Qing; Yang, Yang; Ni, Xu; Xu, Ye-Long; Sun, Xiao-Chen; Chen, Ze-Guo; Feng, Liang; Liu, Xiao-ping; Lu, Ming-Hui; Chen, Yan-Feng

    2015-01-01

    An acoustic asymmetric transmission device exhibiting unidirectional transmission property for acoustic waves is extremely desirable in many practical scenarios. Such a unique property may be realized in various configurations utilizing acoustic Zeeman effects in moving media as well as frequency-conversion in passive nonlinear acoustic systems and in active acoustic systems. Here we demonstrate a new acoustic frequency conversion process in a time-varying system, consisting of a rotating blade and the surrounding air. The scattered acoustic waves from this time-varying system experience frequency shifts, which are linearly dependent on the blade’s rotating frequency. Such scattering mechanism can be well described theoretically by an acoustic linear time-varying perturbation theory. Combining such time-varying scattering effects with highly efficient acoustic filtering, we successfully develop a tunable acoustic unidirectional device with 20 dB power transmission contrast ratio between two counter propagation directions at audible frequencies. PMID:26038886

  15. Vibration testing and analysis using holography

    NASA Technical Reports Server (NTRS)

    1971-01-01

    Time average holography is useful in recording steady state vibrational mode patterns. Phase relationships under steady state conditions are measured with real time holography and special phase shifting techniques. Data from Michelson interferometer verify vibration amplitudes from holographic data.

  16. Model-based optical coherence elastography using acoustic radiation force

    NASA Astrophysics Data System (ADS)

    Aglyamov, Salavat; Wang, Shang; Karpiouk, Andrei; Li, Jiasong; Emelianov, Stanislav; Larin, Kirill V.

    2014-02-01

    Acoustic Radiation Force (ARF) stimulation is actively used in ultrasound elastography to estimate mechanical properties of tissue. Compared with ultrasound imaging, OCT provides advantage in both spatial resolution and signal-to-noise ratio. Therefore, a combination of ARF and OCT technologies can provide a unique opportunity to measure viscoelastic properties of tissue, especially when the use of high intensity radiation pressure is limited for safety reasons. In this presentation we discuss a newly developed theoretical model of the deformation of a layered viscoelastic medium in response to an acoustic radiation force of short duration. An acoustic impulse was considered as an axisymmetric force generated on the upper surface of the medium. An analytical solution of this problem was obtained using the Hankel transform in frequency domain. It was demonstrated that layers at different depths introduce different frequency responses. To verify the developed model, experiments were performed using tissue-simulating, inhomogeneous phantoms of varying mechanical properties. The Young's modulus of the phantoms was varied from 5 to 50 kPa. A single-element focused ultrasound transducer (3.5 MHz) was used to apply the radiation force with various durations on the surface of phantoms. Displacements on the phantom surface were measured using a phase-sensitive OCT at 25 kHz repetition frequency. The experimental results were in good agreement with the modeling results. Therefore, the proposed theoretical model can be used to reconstruct the mechanical properties of tissue based on ARF/OCT measurements.

  17. Cavitating vortex characterization based on acoustic signal detection

    NASA Astrophysics Data System (ADS)

    Digulescu, A.; Murgan, I.; Candel, I.; Bunea, F.; Ciocan, G.; Bucur, D. M.; Dunca, G.; Ioana, C.; Vasile, G.; Serbanescu, A.

    2016-11-01

    In hydraulic turbines operating at part loads, a cavitating vortex structure appears at runner outlet. This helical vortex, called vortex rope, can be cavitating in its core if the local pressure is lower that the vaporization pressure. An actual concern is the detection of the cavitation apparition and the characterization of its level. This paper presents a potentially innovative method for the detection of the cavitating vortex presence based on acoustic methods. The method is tested on a reduced scale facility using two acoustic transceivers positioned in ”V” configuration. The received signals were continuously recorded and their frequency content was chosen to fit the flow and the cavitating vortex. Experimental results showed that due to the increasing flow rate, the signal - vortex interaction is observed as modifications on the received signal's high order statistics and bandwidth. Also, the signal processing results were correlated with the data measured with a pressure sensor mounted in the cavitating vortex section. Finally it is shown that this non-intrusive acoustic approach can indicate the apparition, development and the damping of the cavitating vortex. For real scale facilities, applying this method is a work in progress.

  18. Parallel two-step phase-shifting digital holography.

    PubMed

    Awatsuji, Yasuhiro; Tahara, Tatsuki; Kaneko, Atsushi; Koyama, Takamasa; Nishio, Kenzo; Ura, Shogo; Kubota, Toshihiro; Matoba, Osamu

    2008-07-01

    We propose a parallel two-step phase-shifting digital holography technique capable of instantaneous measurement of three-dimensional objects, with a view toward measurement of dynamically moving objects. The technique is based on phase-shifting interferometry. The proposed technique carries out the two-step phase-shifting method at one time and can be optically implemented by using a phase-shifting array device located in the reference beam. The array device has a periodic two-step phase distribution, and its configuration is simplified compared with that required for three-step and four-step parallel phase-shifting digital holographies. Therefore the optical system of the proposed technique is more suitable for the realization of a parallel phase-shifting digital holography system. We conduct both a numerical simulation and a preliminary experiment in the proposed technique. The results of the simulation and the experiment agree well with those of sequential phase-shifting digital holography, and results are superior to those obtained by conventional digital holography using the Fresnel transform alone. Thus the effectiveness of the proposed technique is verified.

  19. Tunable acoustic waveguide based on vibro-acoustic metamaterials with shunted piezoelectric unit cells

    NASA Astrophysics Data System (ADS)

    Kwon, Byung-Jin; Jung, Jin-Young; Lee, Dooho; Park, Kwang-Chun; Oh, Il-Kwon

    2015-10-01

    We propose a new class of acoustic waveguides with tunable bandgaps (TBs) by using vibro-acoustic metamaterials with shunted periodic piezoelectric unit cells. The unit metamaterial cells that consist of a single crystal piezoelectric transducer and an electrical shunt circuit are designed to induce a strong vibro-acousto-electrical coupling, resulting in a tunable acoustic bandgap as well as local structural resonance and Bragg scattering bandgaps. The present results show that the TB frequency can be actively controlled and the transmission loss of the acoustic wave can be greatly improved by simply changing the inductance values in the shunt circuit.

  20. Mathematical refocusing of images in electronic holography

    SciTech Connect

    Stetson, Karl A.

    2009-07-01

    This paper presents an illustration of mathematical refocusing of images obtained by the HoloFringe300K electronic holography program. The purpose is to demonstrate that this form of electronic holography is equivalent to image-plane, phase-stepped digital holography. The mathematical refocusing method used here differs from those in common use and may have some advantages.

  1. Observer-based beamforming algorithm for acoustic array signal processing.

    PubMed

    Bai, Long; Huang, Xun

    2011-12-01

    In the field of noise identification with microphone arrays, conventional delay-and-sum (DAS) beamforming is the most popular signal processing technique. However, acoustic imaging results that are generated by DAS beamforming are easily influenced by background noise, particularly for in situ wind tunnel tests. Even when arithmetic averaging is used to statistically remove the interference from the background noise, the results are far from perfect because the interference from the coherent background noise is still present. In addition, DAS beamforming based on arithmetic averaging fails to deliver real-time computational capability. An observer-based approach is introduced in this paper. This so-called observer-based beamforming method has a recursive form similar to the state observer in classical control theory, thus holds a real-time computational capability. In addition, coherent background noise can be gradually rejected in iterations. Theoretical derivations of the observer-based beamforming algorithm are carefully developed in this paper. Two numerical simulations demonstrate the good coherent background noise rejection and real-time computational capability of the observer-based beamforming, which therefore can be regarded as an attractive algorithm for acoustic array signal processing.

  2. Analyzing panel acoustic contributions toward the sound field inside the passenger compartment of a full-size automobile.

    PubMed

    Wu, Sean F; Moondra, Manmohan; Beniwal, Ravi

    2015-04-01

    The Helmholtz equation least squares (HELS)-based nearfield acoustical holography (NAH) is utilized to analyze panel acoustic contributions toward the acoustic field inside the interior region of an automobile. Specifically, the acoustic power flows from individual panels are reconstructed, and relative contributions to sound pressure level and spectrum at any point of interest are calculated. Results demonstrate that by correlating the acoustic power flows from individual panels to the field acoustic pressure, one can correctly locate the panel allowing the most acoustic energy transmission into the vehicle interior. The panel on which the surface acoustic pressure amplitude is the highest should not be used as indicative of the panel responsible for the sound field in the vehicle passenger compartment. Another significant advantage of this HELS-based NAH is that measurements of the input data only need to be taken once by using a conformal array of microphones in the near field, and ranking of panel acoustic contributions to any field point can be readily performed. The transfer functions between individual panels of any vibrating structure to the acoustic pressure anywhere in space are calculated not measured, thus significantly reducing the time and effort involved in panel acoustic contributions analyses.

  3. Standing surface acoustic wave (SSAW)-based microfluidic cytometer

    PubMed Central

    Chen, Yuchao; Nawaz, Ahmad Ahsan; Zhao, Yanhui; Huang, Po-Hsun; McCoy, J. Phillip; Levine, Stewart; Wang, Lin; Huang, Tony Jun

    2014-01-01

    The development of microfluidic chip-based cytometers has become an important area due to their advantages of compact size and low cost. Herein, we demonstrate a sheathless microfluidic cytometer which integrates a standing surface acoustic wave (SSAW)-based microdevice capable of 3D particle/cell focusing with a laser-induced fluorescence (LIF) detection system. Using SSAW, our microfluidic cytometer was able to continuously focus microparticles/cells at the pressure node inside a microchannel. Flow cytometry was successfully demonstrated using this system with a coefficient of variation (CV) of less than 10% at a throughput of ~1000 events/s when calibration beads were used. We also demonstrated that fluorescently labeled human promyelocytic leukemia cells (HL-60) could be effectively focused and detected with our SSAW-based system. This SSAW-based microfluidic cytometer did not require any sheath flows or complex structures, and it allowed for simple operation over a wide range of sample flow rates. Moreover, with the gentle, bio-compatible nature of low-power surface acoustic waves, this technique is expected to be able to preserve the integrity of cells and other bioparticles. PMID:24406848

  4. Room Acoustical Simulation Algorithm Based on the Free Path Distribution

    NASA Astrophysics Data System (ADS)

    VORLÄNDER, M.

    2000-04-01

    A new algorithm is presented which provides estimates of impulse responses in rooms. It is applicable to arbitrary shaped rooms, thus including non-diffuse spaces like workrooms or offices. In the latter cases, for instance, sound propagation curves are of interest to be applied in noise control. In the case of concert halls and opera houses, the method enables very fast predictions of room acoustical criteria like reverberation time, strength or clarity. The method is based on a low-resolved ray tracing and recording of the free paths. Estimates of impulse responses are derived from evaluation of the free path distribution and of the free path transition probabilities.

  5. Field Assessment of Acoustic-Doppler Based Discharge Measurements

    USGS Publications Warehouse

    Mueller, D.S.; ,

    2002-01-01

    The use of equipment based on the Doppler principle for measuring water velocity and computing discharge is common within the U.S. Geological Survey (USGS). The instruments and software have changed appreciably during the last 5 years; therefore, the USGS has begun a field validation of the instruments currently (2002) available for making discharge measurements from a moving boat in streams of various sizes. Instruments manufactured by SonTek/YSI2 and RD Instruments, Inc. were used to collect discharge data at five different sites. One or more traditional discharge measurements were made by the use of a Price AA current meter and standard USGS procedures with the acoustic instruments at each site during data collection. The discharges measured with the acoustic instruments were compared with the discharges measured with Price AA meters and the current USGS stage-discharge rating for each site. The mean discharges measured by each acoustic instrument were within 5 percent of the Price AA-based measurement and (or) discharge from the stage-discharge rating. Additional analysis of the data collected indicates that the coefficient of variation of the discharge measurements consistently was less for the RD Instruments, Inc. Rio Grandes than it was for the SonTek/YSI RiverSurveyors. The bottom-tracking referenced measurement had a lower coefficient of variation than the differentially corrected global positioning system referenced measurements. It was observed that the higher frequency RiverSurveyors measured a moving bed more often than the lower frequency Rio Grandes. The detection of a moving bed caused RiverSurveyors to be consistently biased low when referenced to bottom tracking. Differentially corrected global positioning system data may be used to remove the bias observed in the bottom-tracking referenced measurements.

  6. Art of color holography: pioneers in change

    NASA Astrophysics Data System (ADS)

    Richardson, Martin J.; Bjelkhagen, Hans I.

    2000-10-01

    The possibility to easily record full color holograms, (simply color holograms) has opened new possibilities for art holographers. This paper includes details concerning preparation of subject matter and its practical suitability for color holographic recordings from practical working sessions at ARTCAPI Atelier de Recherche Technique et de Creation Artistique en Physique et en Informatique in France. Martin Richardson as invited artist and Hans Bjelkhagen as scientist holographer describe color holography to a wider public audience through artistic display. Both directly recorded true color images and computer-generated images based on the ZEBRA printing technique are to be presented.

  7. Model-based acoustic characterization and classification of irregular-shaped targets: Application to fisheries and zooplankton acoustics

    NASA Astrophysics Data System (ADS)

    Chu, Dezhang; Stanton, Timothy K.; Wiebe, Peter H.

    2002-11-01

    Acoustic scattering by fish and zooplankton is a complicated function of the geometrical and physical properties of the targets, as well as the environmental and sonar system parameters. The shape and anatomy of zooplankton vary significantly from taxa to taxa and their dominant scattering mechanisms can be completely different. As a result, the acoustic classification of such targets is extremely difficult and often nonunique. To reduce the ambiguity and nonuniqueness, a number of model-based methods are presented. These methods use the temporal, spatial, spectral, and statistical signatures of acoustical scattering signals and can be applied to a variety of acoustic systems, including narrow-band, broadband, and multifrequency systems. The methods also depend strongly on whether or not the targets are resolved. Individual targets with different shapes and material properties have their unique characteristics and can be classified acoustically in terms of their size, orientation, scattering mechanisms, as well as their material properties. Results of applying these methods to the laboratory and field data will be presented and analyzed. [Work supported by ONR, NSF, and the Comer Science and Education Foundation.

  8. Waveform-preserved unidirectional acoustic transmission based on impedance-matched acoustic metasurface and phononic crystal

    NASA Astrophysics Data System (ADS)

    Song, Ai-Ling; Chen, Tian-Ning; Wang, Xiao-Peng; Wan, Le-Le

    2016-08-01

    The waveform distortion happens in most of the unidirectional acoustic transmission (UAT) devices proposed before. In this paper, a novel type of waveform-preserved UAT device composed of an impedance-matched acoustic metasurface (AMS) and a phononic crystal (PC) structure is proposed and numerically investigated. The acoustic pressure field distributions and transmittance are calculated by using the finite element method. The subwavelength AMS that can modulate the wavefront of the transmitted wave at will is designed and the band structure of the PC structure is calculated and analyzed. The sound pressure field distributions demonstrate that the unidirectional acoustic transmission can be realized by the proposed UAT device without changing the waveforms of the output waves, which is the distinctive feature compared with the previous UAT devices. The physical mechanism of the unidirectional acoustic transmission is discussed by analyzing the refraction angle changes and partial band gap map. The calculated transmission spectra show that the UAT device is valid within a relatively broad frequency range. The simulation results agree well with the theoretical predictions. The proposed UAT device provides a good reference for designing waveform-preserved UAT devices and has potential applications in many fields, such as medical ultrasound, acoustic rectifiers, and noise insulation.

  9. Industrial Application Of Instant Holography

    NASA Astrophysics Data System (ADS)

    Schorner, J.; Rottenkolber, H.

    1983-10-01

    The development of holographic test methods has lead to a wide industrial application. Today serial tests of aircraft tyres with holography have become routine. A large chemical company is testing their plastic materials like tanks, wheels and fans with the method of holographic interferometry. In the power engine industry turbine blades are tested holographically to find an optimal shape and to test the vibration behaviour. The automotive industry is using holographic methods' for construction optimization. The economic application of these test methods was possible by using instant holography. The principle of a new hologramrecorder is presented. The application of this equipment is shown in examples of testing materials, optimizing constructions and vibration analysis.

  10. Green light for pulsed holography

    NASA Astrophysics Data System (ADS)

    Olson, Bernadette L.; Olson, Ron B.; Hess, Robert A.

    1993-03-01

    This paper reviews the historical reasons why so few neodymium:yttrium aluminum garnet (Nd:YAG) lasers are dedicated to display holography in comparison to ruby lasers, why positive light holographics (PLH) decided to use an Nd:YAG/Nd:Glass laser and what kind of configuration is used. A practical overview on how to use an Nd:YAG/Nd:Glass laser for deep-image holography is discussed, and an evaluation of the transmission holograms recorded with an Nd:YAG/Nd:Glass laser is made in particular from an image planing point of view.

  11. Holography with a neutron interferometer.

    PubMed

    Sarenac, Dusan; Huber, Michael G; Heacock, Benjamin; Arif, Muhammad; Clark, Charles W; Cory, David G; Shahi, Chandra B; Pushin, Dmitry A

    2016-10-03

    We use a Mach-Zehnder interferometer to perform neutron holography of a spiral phase plate. The object beam passes through a spiral phase plate, acquiring the phase twist characteristic of orbital angular momentum states. The reference beam passes through a fused silica prism, acquiring a linear phase gradient. The resulting hologram is a fork dislocation image, which could be used to reconstruct neutron beams with various orbital angular momenta. This work paves the way for novel applications of neutron holography, diffraction and imaging.

  12. Particle filtering based structural assessment with acoustic emission sensing

    NASA Astrophysics Data System (ADS)

    Yan, Wuzhao; Abdelrahman, Marwa; Zhang, Bin; Ziehl, Paul

    2017-02-01

    Nuclear structures are designed to withstand severe loading events under various stresses. Over time, aging of structural systems constructed with concrete and steel will occur. This deterioration may reduce service life of nuclear facilities and/or lead to unnecessary or untimely repairs. Therefore, online monitoring of structures in nuclear power plants and waste storage has drawn significant attention in recent years. Of many existing non-destructive evaluation and structural monitoring approaches, acoustic emission is promising for assessment of structural damage because it is non-intrusive and is sensitive to corrosion and crack growth in reinforced concrete elements. To provide a rapid, actionable, and graphical means for interpretation Intensity Analysis plots have been developed. This approach provides a means for classification of damage. Since the acoustic emission measurement is only an indirect indicator of structural damage, potentially corrupted by non-genuine data, it is more suitable to estimate the states of corrosion and cracking in a Bayesian estimation framework. In this paper, we will utilize the accelerated corrosion data from a specimen at the University of South Carolina to develop a particle filtering-based diagnosis and prognosis algorithm. Promising features of the proposed algorithm are described in terms of corrosion state estimation and prediction of degradation over time to a predefined threshold.

  13. Detection of impulsive sources from an aerostat-based acoustic array data collection system

    NASA Astrophysics Data System (ADS)

    Prather, Wayne E.; Clark, Robert C.; Strickland, Joshua; Frazier, Wm. Garth; Singleton, Jere

    2009-05-01

    An aerostat based acoustic array data collection system was deployed at the NATO TG-53 "Acoustic Detection of Weapon Firing" Joint Field Experiment conducted in Bourges, France during the final two weeks of June 2008. A variety of impulsive sources including mortar, artillery, gunfire, RPG, and explosive devices were fired during the test. Results from the aerostat acoustic array will be presented against the entire range of sources.

  14. Broadband Focusing Acoustic Lens Based on Fractal Metamaterials.

    PubMed

    Song, Gang Yong; Huang, Bei; Dong, Hui Yuan; Cheng, Qiang; Cui, Tie Jun

    2016-10-26

    Acoustic metamaterials are artificial structures which can manipulate sound waves through their unconventional effective properties. Different from the locally resonant elements proposed in earlier studies, we propose an alternate route to realize acoustic metamaterials with both low loss and large refractive indices. We describe a new kind of acoustic metamaterial element with the fractal geometry. Due to the self-similar properties of the proposed structure, broadband acoustic responses may arise within a broad frequency range, making it a good candidate for a number of applications, such as super-resolution imaging and acoustic tunneling. A flat acoustic lens is designed and experimentally verified using this approach, showing excellent focusing abilities from 2 kHz and 5 kHz in the measured results.

  15. Broadband Focusing Acoustic Lens Based on Fractal Metamaterials

    NASA Astrophysics Data System (ADS)

    Song, Gang Yong; Huang, Bei; Dong, Hui Yuan; Cheng, Qiang; Cui, Tie Jun

    2016-10-01

    Acoustic metamaterials are artificial structures which can manipulate sound waves through their unconventional effective properties. Different from the locally resonant elements proposed in earlier studies, we propose an alternate route to realize acoustic metamaterials with both low loss and large refractive indices. We describe a new kind of acoustic metamaterial element with the fractal geometry. Due to the self-similar properties of the proposed structure, broadband acoustic responses may arise within a broad frequency range, making it a good candidate for a number of applications, such as super-resolution imaging and acoustic tunneling. A flat acoustic lens is designed and experimentally verified using this approach, showing excellent focusing abilities from 2 kHz and 5 kHz in the measured results.

  16. Broadband Focusing Acoustic Lens Based on Fractal Metamaterials

    PubMed Central

    Song, Gang Yong; Huang, Bei; Dong, Hui Yuan; Cheng, Qiang; Cui, Tie Jun

    2016-01-01

    Acoustic metamaterials are artificial structures which can manipulate sound waves through their unconventional effective properties. Different from the locally resonant elements proposed in earlier studies, we propose an alternate route to realize acoustic metamaterials with both low loss and large refractive indices. We describe a new kind of acoustic metamaterial element with the fractal geometry. Due to the self-similar properties of the proposed structure, broadband acoustic responses may arise within a broad frequency range, making it a good candidate for a number of applications, such as super-resolution imaging and acoustic tunneling. A flat acoustic lens is designed and experimentally verified using this approach, showing excellent focusing abilities from 2 kHz and 5 kHz in the measured results. PMID:27782216

  17. Hybridization approach to in-line and off-axis (electron) holography for superior resolution and phase sensitivity

    PubMed Central

    Ozsoy-Keskinbora, C.; Boothroyd, C. B.; Dunin-Borkowski, R. E.; van Aken, P. A.; Koch, C. T.

    2014-01-01

    Holography - originally developed for correcting spherical aberration in transmission electron microscopes - is now used in a wide range of disciplines that involve the propagation of waves, including light optics, electron microscopy, acoustics and seismology. In electron microscopy, the two primary modes of holography are Gabor's original in-line setup and an off-axis approach that was developed subsequently. These two techniques are highly complementary, offering superior phase sensitivity at high and low spatial resolution, respectively. All previous investigations have focused on improving each method individually. Here, we show how the two approaches can be combined in a synergetic fashion to provide phase information with excellent sensitivity across all spatial frequencies, low noise and an efficient use of electron dose. The principle is also expected to be widely to applications of holography in light optics, X-ray optics, acoustics, ultra-sound, terahertz imaging, etc. PMID:25387480

  18. Hybridization approach to in-line and off-axis (electron) holography for superior resolution and phase sensitivity

    NASA Astrophysics Data System (ADS)

    Ozsoy-Keskinbora, C.; Boothroyd, C. B.; Dunin-Borkowski, R. E.; van Aken, P. A.; Koch, C. T.

    2014-11-01

    Holography - originally developed for correcting spherical aberration in transmission electron microscopes - is now used in a wide range of disciplines that involve the propagation of waves, including light optics, electron microscopy, acoustics and seismology. In electron microscopy, the two primary modes of holography are Gabor's original in-line setup and an off-axis approach that was developed subsequently. These two techniques are highly complementary, offering superior phase sensitivity at high and low spatial resolution, respectively. All previous investigations have focused on improving each method individually. Here, we show how the two approaches can be combined in a synergetic fashion to provide phase information with excellent sensitivity across all spatial frequencies, low noise and an efficient use of electron dose. The principle is also expected to be widely to applications of holography in light optics, X-ray optics, acoustics, ultra-sound, terahertz imaging, etc.

  19. Time dependent holography

    NASA Astrophysics Data System (ADS)

    Das, Diptarka

    One of the most important results emerging from string theory is the gauge gravity duality (AdS/CFT correspondence) which tells us that certain problems in particular gravitational backgrounds can be exactly mapped to a particular dual gauge theory a quantum theory very similar to the one explaining the interactions between fundamental subatomic particles. The chief merit of the duality is that a difficult problem in one theory can be mapped to a simpler and solvable problem in the other theory. The duality can be used both ways. Most of the current theoretical framework is suited to study equilibrium systems, or systems where time dependence is at most adiabatic. However in the real world, systems are almost always out of equilibrium. Generically these scenarios are described by quenches, where a parameter of the theory is made time dependent. In this dissertation I describe some of the work done in the context of studying quantum quench using the AdS/CFT correspondence. We recover certain universal scaling type of behavior as the quenching is done through a quantum critical point. Another question that has been explored in the dissertation is time dependence of the gravity theory. Present cosmological observations indicate that our universe is accelerating and is described by a spacetime called de-Sitter(dS). In 2011 there had been a speculation over a possible duality between de-Sitter gravity and a particular field theory (Euclidean SP(N) CFT). However a concrete realization of this proposition was still lacking. Here we explicitly derive the dS/CFT duality using well known methods in field theory. We discovered that the time dimension emerges naturally in the derivation. We also describe further applications and extensions of dS/CFT. KEYWORDS: Holography, AdS/CFT correspondence, Quantum Quench, dS/CFT correspondence, Chaos.

  20. Rainbow holography and its applications

    NASA Astrophysics Data System (ADS)

    Vlasov, N. G.; Ivanov, Vladimir S.

    1993-09-01

    The general equations of the rainbow holography are deduced. Their analysis makes it possible to offer different methods of the rainbow holographic images production. A new way of using the rainbow holograms as optical elements for effective color illuminating of transparent, specular, and polished objects is proposed. Application fields are the advertising industry, shop windows design, etc.

  1. Multilayer-graphene-based amplifier of surface acoustic waves

    SciTech Connect

    Yurchenko, Stanislav O. Komarov, Kirill A.; Pustovoit, Vladislav I.

    2015-05-15

    The amplification of surface acoustic waves (SAWs) by a multilayer graphene (MLG)-based amplifier is studied. The conductivity of massless carriers (electrons or holes) in graphene in an external drift electric field is calculated using Boltzmann’s equation. At some carrier drift velocities, the real part of the variable conductivity becomes negative and MLG can be employed in SAW amplifiers. Amplification of Blustein’s and Rayleigh’s SAWs in CdS, a piezoelectric hexagonal crystal of the symmetry group C{sub 6v}, is considered. The corresponding equations for SAW propagation in the device are derived and can be applied to other substrate crystals of the same symmetry. The results of the paper indicate that MLG can be considered as a perspective material for SAW amplification and related applications.

  2. Monaural sound localization based on structure-induced acoustic resonance.

    PubMed

    Kim, Keonwook; Kim, Youngwoong

    2015-02-06

    A physical structure such as a cylindrical pipe controls the propagated sound spectrum in a predictable way that can be used to localize the sound source. This paper designs a monaural sound localization system based on multiple pyramidal horns around a single microphone. The acoustic resonance within the horn provides a periodicity in the spectral domain known as the fundamental frequency which is inversely proportional to the radial horn length. Once the system accurately estimates the fundamental frequency, the horn length and corresponding angle can be derived by the relationship. The modified Cepstrum algorithm is employed to evaluate the fundamental frequency. In an anechoic chamber, localization experiments over azimuthal configuration show that up to 61% of the proper signal is recognized correctly with 30% misfire. With a speculated detection threshold, the system estimates direction 52% in positive-to-positive and 34% in negative-to-positive decision rate, on average.

  3. Surface Acoustic Wave Tag-Based Coherence Multiplexing

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert C. (Inventor); Malocha, Donald (Inventor); Saldanha, Nancy (Inventor)

    2016-01-01

    A surface acoustic wave (SAW)-based coherence multiplexing system includes SAW tags each including a SAW transducer, a first SAW reflector positioned a first distance from the SAW transducer and a second SAW reflector positioned a second distance from the SAW transducer. A transceiver including a wireless transmitter has a signal source providing a source signal and circuitry for transmitting interrogation pulses including a first and a second interrogation pulse toward the SAW tags, and a wireless receiver for receiving and processing response signals from the SAW tags. The receiver receives scrambled signals including a convolution of the wideband interrogation pulses with response signals from the SAW tags and includes a computing device which implements an algorithm that correlates the interrogation pulses or the source signal before transmitting against the scrambled signals to generate tag responses for each of the SAW tags.

  4. Multilayer-graphene-based amplifier of surface acoustic waves

    NASA Astrophysics Data System (ADS)

    Yurchenko, Stanislav O.; Komarov, Kirill A.; Pustovoit, Vladislav I.

    2015-05-01

    The amplification of surface acoustic waves (SAWs) by a multilayer graphene (MLG)-based amplifier is studied. The conductivity of massless carriers (electrons or holes) in graphene in an external drift electric field is calculated using Boltzmann's equation. At some carrier drift velocities, the real part of the variable conductivity becomes negative and MLG can be employed in SAW amplifiers. Amplification of Blustein's and Rayleigh's SAWs in CdS, a piezoelectric hexagonal crystal of the symmetry group C6v, is considered. The corresponding equations for SAW propagation in the device are derived and can be applied to other substrate crystals of the same symmetry. The results of the paper indicate that MLG can be considered as a perspective material for SAW amplification and related applications.

  5. Microcontroller-based underwater acoustic ECG telemetry system.

    PubMed

    Istepanian, R S; Woodward, B

    1997-06-01

    This paper presents a microcontroller-based underwater acoustic telemetry system for digital transmission of the electrocardiogram (ECG). The system is designed for the real time, through-water transmission of data representing any parameter, and it was used initially for transmitting in multiplexed format the heart rate, breathing rate and depth of a diver using self-contained underwater breathing apparatus (SCUBA). Here, it is used to monitor cardiovascular reflexes during diving and swimming. The programmable capability of the system provides an effective solution to the problem of transmitting data in the presence of multipath interference. An important feature of the paper is a comparative performance analysis of two encoding methods, Pulse Code Modulation (PCM) and Pulse Position Modulation (PPM).

  6. Combined Helmholtz equation-least squares method for reconstructing acoustic radiation from arbitrarily shaped objects

    NASA Astrophysics Data System (ADS)

    Wu, Sean F.; Zhao, Xiang

    2002-07-01

    A combined Helmholtz equation-least squares (CHELS) method is developed for reconstructing acoustic radiation from an arbitrary object. This method combines the advantages of both the HELS method and the Helmholtz integral theory based near-field acoustic holography (NAH). As such it allows for reconstruction of the acoustic field radiated from an arbitrary object with relatively few measurements, thus significantly enhancing the reconstruction efficiency. The first step in the CHELS method is to establish the HELS formulations based on a finite number of acoustic pressure measurements taken on or beyond a hypothetical spherical surface that encloses the object under consideration. Next enough field acoustic pressures are generated using the HELS formulations and taken as the input to the Helmholtz integral formulations implemented through the boundary element method (BEM). The acoustic pressure and normal component of the velocity at the discretized nodes on the surface are then determined by solving two matrix equations using singular value decomposition (SVD) and regularization techniques. Also presented are in-depth analyses of the advantages and limitations of the CHELS method. Examples of reconstructing acoustic radiation from separable and nonseparable surfaces are demonstrated. copyright 2002 Acoustical Society of America.

  7. EDITORIAL: Optical tomography and digital holography

    NASA Astrophysics Data System (ADS)

    Coupland, Jeremy; Lobera, Julia

    2008-07-01

    terms the papers we present describe closely related holographic techniques that address application areas within the field of engineering. The application of digital holography to 3D fluid flow measurement is addressed by several authors. Salah et al demonstrate the simplicity of digital holography with an in-line multiple exposure holographic system using a low-cost laser diode. Soria and Atkinson discuss limitations of low NA holography in fluid velocimetry and demonstrate the potential of a multiple camera, in-line technique which they call Tomographic Digital Holographic Particle Image Velocimetry (Tomo-HPIV). Problems caused by the twin images (real and virtual) of in-line HPIV are described by Ooms et al. It is shown how sign ambiguity can be eliminated and bias errors suppressed by the application of a suitable threshold in piecewise correlation of the reconstructed field. Denis et al explain the problem of twin image removal as a deconvolution process and compare suppression algorithms based on wavelet decomposition. This process can be considered as an inverse problem and the benefits of this approach are discussed with reference to particulate holograms by Gire et al. Of course, the twin image problem can be solved by off-axis holographic geometries which, in effect, add a carrier modulation. Arroyo presents a comparison of carrier modulation strategies that have been presented in the literature and shows circumstances in which the information in each of the real and virtual images can be separated when the sensor resolution is less than that required by the NA of the objective. State-of-the-art digital holographic microscopy (DHM) is presented by Kühn et al. This paper uses an off-axis geometry that simultaneously records images at two wavelengths. The microscope allows the surface profile to be measured from a single recording and sub-nanometre axial resolution is demonstrated. Another interesting application of DHM is addressed by Grilli et al. They

  8. Conoscopic holography for image registration: a feasibility study

    NASA Astrophysics Data System (ADS)

    Lathrop, Ray A.; Cheng, Tiffany T.; Webster, Robert J., III

    2009-02-01

    Preoperative image data can facilitate intrasurgical guidance by revealing interior features of opaque tissues, provided image data can be accurately registered to the physical patient. Registration is challenging in organs that are deformable and lack features suitable for use as alignment fiducials (e.g. liver, kidneys, etc.). However, provided intraoperative sensing of surface contours can be accomplished, a variety of rigid and deformable 3D surface registration techniques become applicable. In this paper, we evaluate the feasibility of conoscopic holography as a new method to sense organ surface shape. We also describe potential advantages of conoscopic holography, including the promise of replacing open surgery with a laparoscopic approach. Our feasibility study investigated use of a tracked off-the-shelf conoscopic holography unit to perform a surface scans on several types of biological and synthetic phantom tissues. After first exploring baseline accuracy and repeatability of distance measurements, we performed a number of surface scan experiments on the phantom and ex vivo tissues with a variety of surface properties and shapes. These indicate that conoscopic holography is capable of generating surface point clouds of at least comparable (and perhaps eventually improved) accuracy in comparison to published experimental laser triangulation-based surface scanning results.

  9. Study of piezo based sensors for acoustic particle detection

    NASA Astrophysics Data System (ADS)

    Anton, G.; Graf, K.; Hößl, J.; Kappes, A.; Karg, T.; Katz, U.; Kretschmer, W.; Kuch, S.; Lahmann, R.; Naumann, C.; Salomon, K.

    2006-11-01

    We present a characterisation of piezo sensors for acoustic particle detection. Electrical impedance, mechanical displacement and the sensitivity of piezo sensors were measured and modelled using a simple equivalent circuit diagram. In addition, finite element simulations were performed to describe the behaviour of the sensors. Their application for acoustic particle detection is discussed.

  10. Acoustic Emission Based Surveillance System for Prediction of Stress Fractures

    DTIC Science & Technology

    2007-09-01

    withstand irrigation. The transducers were mounted on the specimen using cyanoacrylate glue . The acoustic emission signal from the transducers was...respectively. An acoustic emission transducer (Pico, PAC, NJ) was mounted at the mid-span of the specimens using cyanoacrylate glue . Signal from the

  11. Application of Compressive Sensing to Digital Holography

    DTIC Science & Technology

    2015-05-01

    AFRL-RY-WP-TR-2015-0071 APPLICATION OF COMPRESSIVE SENSING TO DIGITAL HOLOGRAPHY Mark Neifeld University of Arizona...From - To) May 2015 Final 3 September 2013 – 27 February 2015 4. TITLE AND SUBTITLE APPLICATION OF COMPRESSIVE SENSING TO DIGITAL HOLOGRAPHY 5a...from under- sampled data. This work presents a new reconstruction algorithm for use with under-sampled digital holography measurements and yields

  12. Digital holography and 3-D imaging.

    PubMed

    Banerjee, Partha; Barbastathis, George; Kim, Myung; Kukhtarev, Nickolai

    2011-03-01

    This feature issue on Digital Holography and 3-D Imaging comprises 15 papers on digital holographic techniques and applications, computer-generated holography and encryption techniques, and 3-D display. It is hoped that future work in the area leads to innovative applications of digital holography and 3-D imaging to biology and sensing, and to the development of novel nonlinear dynamic digital holographic techniques.

  13. Acoustic Source Localization in Aircraft Interiors Using Microphone Array Technologies

    NASA Technical Reports Server (NTRS)

    Sklanka, Bernard J.; Tuss, Joel R.; Buehrle, Ralph D.; Klos, Jacob; Williams, Earl G.; Valdivia, Nicolas

    2006-01-01

    Using three microphone array configurations at two aircraft body stations on a Boeing 777-300ER flight test, the acoustic radiation characteristics of the sidewall and outboard floor system are investigated by experimental measurement. Analysis of the experimental data is performed using sound intensity calculations for closely spaced microphones, PATCH Inverse Boundary Element Nearfield Acoustic Holography, and Spherical Nearfield Acoustic Holography. Each method is compared assessing strengths and weaknesses, evaluating source identification capability for both broadband and narrowband sources, evaluating sources during transient and steady-state conditions, and quantifying field reconstruction continuity using multiple array positions.

  14. Ultrasonic Imaging of Subsurface Objects Using Photorefractive Dynamic Holography

    SciTech Connect

    Deason, Vance Albert; Telschow, Kenneth Louis; Watson, Scott Marshall

    2001-07-01

    The INEEL has developed a photorefractive ultrasonic imaging technology that records both phase and amplitude of ultrasonic waves on the surface of solids. Phase locked dynamic holography provides full field images of these waves scattered from subsurface defects in solids, and these data are compared with theoretical predictions. Laser light reflected by a vibrating surface is imaged into a photorefractive material where it is mixed in a heterodyne technique with a reference wave. This demodulates the data and provides an image of the ultrasonic waves in either 2 wave or 4 wave mixing mode. These data images are recorded at video frame rates and show phase locked traveling or resonant acoustic waves. This technique can be used over a broad range of ultrasonic frequencies. Acoustic frequencies from 2 kHz to 10 MHz have been imaged, and a point measuring (non-imaging) version of the system has measured picometer amplitudes at 1 GHz.

  15. Aspects of holography

    NASA Astrophysics Data System (ADS)

    Kaplan, Jared Daniel

    The principle of holography---that theories of gravity should be described in terms of their boundaries---has been the driving force behind many great strides in quantum gravity, gauge theory, and even in phenomenology. The most concrete example of holographic duality is the AdS/CFT correspondence, which relates quantum gravity in Anti-deSitter space to a Conformal Field Theory in Minkowski space. In this thesis we begin with a chapter on black holes in the AdS/CFT duality, and then move on to the main line of development, where we describe the exciting first steps towards the discovery of a holographic duality for quantum gravity in flat spacetime. A holographic description of flat spacetime would be a theory of the Scattering Matrix, which contains the quantum mechanical amplitudes that determine how incoming states from past infinity scatter into outgoing states at future infinity. We suspect that a holographic duality between a local spacetime description of quantum gravity and a non-local boundary description of the S-Matrix would be a weak coupling-weak coupling duality. We work towards this concrete goal from the bottom up by studying new methods for computing scattering amplitudes. We begin by studying the BCFW Recursion Relations, which are an explicitly non-local, boundary oriented method for computing tree-level scattering amplitudes. We give an elementary derivation of these relations for general theories in any number of dimensions, showing that their existence is a deep feature of field theory. Next we argue that, counter to naive expectations, N = 8 Supergravity may be the simplest quantum field theory. We demonstrate this by explicitly solving its one-loop S-Matrix with techniques that rely on our understanding of tree amplitudes to vastly simplify calculations. Finally, we show that the BCFW recursion relations find their natural home in Twistor Space, where it is possible to formulate classical scattering theory in a beautiful and manifestly

  16. Digital Holography Display (2)

    NASA Astrophysics Data System (ADS)

    Lee, Cheok Peng; Asundi, A.; Yu, Yang; Xiao, Zhen Zhong

    This paper describes the extension work from the last Digital Holography Projector System. From the developed works shows that, some unforeseen factors have created the difficulties for the system alignment. Such factors are the DMD frame rate, light source and diffractive zero order. It is really the challenging development works to achieve the virtual 3D model display on the high speed rotation screen. The three most key factors are emphasizing: 1) The display device's frame rate; 2) The light source orientation angle; and 3) The zero order filtering optic. 1) This device's is the digital micro mirror, in short is DMD. It is the high speed switching device has developed by the most recent technology. The switching frame rate can go up as high as 291fps. At first, the 8 bits depth file must be digitalized and stored for DMD onboard Ram. The digitalized data are transmitting from the PC USB to DMD onboard Ram. Instead of the data are downloading directly from the PC to DVI or VGA during display, this downloading method cause slower down the display speed, which is the common frame rate of 30 Hz. Next, the onboard Ram data then transfer to the DMD mirror's for display, at the 8 bits 291 fps speed. At this frame rate, the display 2D image can almost cover for 10 of out of the 360 0 in 1 revolution. 2) This laser light source must be installed such that free for orientated in any arbitrary angle from 220 to 450. Which is normalized to the DMD mirrors and the brief sketch show on figure (a). The purpose of orientated the light source is ensure that multi diffractive order would be reflected straight from the mirrors. (This multi diffractive order is the phenomenon of the digital micro mirror's characteristic). This mean, the reconstruct images would be followed the DMD normalized direction reflected up to fibre conduit. Moreover, this orientated method install of the laser light source is making space for other optical lenses or device driver/controller. Because, all

  17. 'Micromanaging de Sitter holography'

    SciTech Connect

    Dong, Xi; Horn, Bart; Silverstein, Eva; Torroba, Gonzalo; /SLAC /Stanford U., Phys. Dept. /Santa Barbara, KITP

    2010-08-26

    We develop tools to engineer de Sitter vacua with semi-holographic duals, using elliptic fibrations and orientifolds to uplift Freund-Rubin compactifications with CFT duals. The dual brane construction is compact and constitutes a microscopic realization of the dS/dS correspondence, realizing d-dimensional de Sitter space as a warped compactification down to (d-1)-dimensional de Sitter gravity coupled to a pair of large-N matter sectors. This provides a parametric microscopic interpretation of the Gibbons-Hawking entropy. We illustrate these ideas with an explicit class of examples in three dimensions, and describe ongoing work on four-dimensional constructions. The Gibbons-Hawking entropy of the de Sitter horizon [1] invites a microscopic interpretation and a holographic formulation of inflating spacetimes. Much progress was made in the analogous problem in black hole physics using special black holes in string theory whose microstates could be reliably counted, such as those analyzed in [2,3]; this led to the AdS/CFT correspondence [4]. In contrast, a microscopic understanding of the entropy of de Sitter space is more difficult for several reasons including its potential dynamical connections to other backgrounds (metastability), the absence of a non-fluctuating timelike boundary, and the absence of supersymmetry. In this paper, we develop a class of de Sitter constructions in string theory, built up from AdS/CFT dual pairs along the lines of [5], which are simple enough to provide a microscopic accounting of the parametric scaling of the Gibbons-Hawking entropy. These models realize microscopically a semi-holographic description of metastable de Sitter space which had been derived macroscopically in [6]. It would also be interesting to connect this to other approaches to de Sitter holography such as [7, 8] and to other manifestations of the de Sitter entropy such as [9]. The construction is somewhat analogous to neutral black branes analyzed in [11]. We will

  18. Holography for automotive head-up displays

    NASA Astrophysics Data System (ADS)

    Ramsbottom, Andrew P.; Sergeant, Shirley A.; Sheel, David W.

    1992-05-01

    There is increasing interest in head-up-displays (HUDs) for automotive use. A number of technologies could be employed for the combiner function including plain glass reflection, dielectric enhancement, and holography. This paper will consider the potential role for conformal holography as the combiner element by initially reviewing the system requirements from an optical design view, how these differ significantly from an avionic HUD, and how they relate to material characteristics and process features. This will involve a consideration in some detail of the effects of specified hologram properties and lamination features on the optical performance and image characteristic of a car HUD. In particular, we shall examine such features as hologram efficiency, bandwidth, tuning position, environmental stability, tolerances, and film lamination effects and how these may influence the key optical characteristics of the image, i.e., distortions, blur, brightness, double imaging (separation and contrast) outside world view, etc.. A theoretical model based on Kogelnik coupled wave theory will be used to illustrate the various tradeoffs between hologram properties and process, image features, and display characteristics (bandwidth, polarization, etc.). This analysis will be related to properties of currently available holographic materials with reference to recent experimental work.

  19. Enhanced vibration based energy harvesting using embedded acoustic black holes

    NASA Astrophysics Data System (ADS)

    Zhao, L.; Semperlotti, F.; Conlon, S. C.

    2014-03-01

    In this paper, we investigate the use of dynamic structural tailoring via the concept of an Acoustic Black Hole (ABH) to enhance the performance of piezoelectric based energy harvesting from operational mechanical vibrations. The ABH is a variable thickness structural feature that can be embedded in the host structure allowing a smooth reduction of the phase velocity while minimizing the amplitude of reflected waves. The ABH thickness variation is typically designed according to power-law profiles. As a propagating wave enters the ABH, it is progressively slowed down while its wavelength is compressed. This effect results in structural areas with high energy density that can be exploited effectively for energy harvesting. The potential of ABH for energy harvesting is shown via a numerical study based on fully coupled finite element electromechanical models of an ABH tapered plate with surface mounted piezo-transducers. The performances of the novel design are evaluated by direct comparison with a non-tapered structure in terms of energy ratios and attenuation indices. Results show that the tailored structural design allows a drastic increase in the harvested energy both for steady state and transient excitation. Performance dependencies of key design parameters are also investigated.

  20. Segregation of complex acoustic scenes based on temporal coherence

    PubMed Central

    Teki, Sundeep; Chait, Maria; Kumar, Sukhbinder; Shamma, Shihab; Griffiths, Timothy D

    2013-01-01

    In contrast to the complex acoustic environments we encounter everyday, most studies of auditory segregation have used relatively simple signals. Here, we synthesized a new stimulus to examine the detection of coherent patterns (‘figures’) from overlapping ‘background’ signals. In a series of experiments, we demonstrate that human listeners are remarkably sensitive to the emergence of such figures and can tolerate a variety of spectral and temporal perturbations. This robust behavior is consistent with the existence of automatic auditory segregation mechanisms that are highly sensitive to correlations across frequency and time. The observed behavior cannot be explained purely on the basis of adaptation-based models used to explain the segregation of deterministic narrowband signals. We show that the present results are consistent with the predictions of a model of auditory perceptual organization based on temporal coherence. Our data thus support a role for temporal coherence as an organizational principle underlying auditory segregation. DOI: http://dx.doi.org/10.7554/eLife.00699.001 PMID:23898398

  1. Bubble-based acoustic micropropulsors: active surfaces and mixers.

    PubMed

    Bertin, Nicolas; Spelman, Tamsin A; Combriat, Thomas; Hue, Hervé; Stéphan, Olivier; Lauga, Eric; Marmottant, Philippe

    2017-04-11

    Acoustic micropropulsors present great potential for microfluidic applications. The propulsion is based on encapsulated 20 μm bubbles excited by a contacless ultrasonic transducer. The vibrating bubbles then generate a powerful streaming flow, with speeds 1-100 mm s(-1) in water, through the action of viscous stresses. In this paper we introduce a full toolbox of micropropulsors using a versatile three-dimensional (3D) microfabrication setup. Doublets and triplets of propulsors are introduced, and the flows they generate are predicted by a theoretical hydrodynamic model. We then introduce whole surfaces covered with propulsors, which we term active surfaces. These surfaces are excited by a single ultrasonic wave, can generate collective flows and may be harnessed for mixing purposes. Several patterns of propulsors are tested, and the flows produced by the two most efficient mixers are predicted by a simple theoretical model based on flow singularities. In particular, the vortices generated by the most efficient pattern, an L-shaped mixer, are analysed in detail.

  2. Modeling and validation of polyurethane based passive underwater acoustic absorber.

    PubMed

    Jayakumari, V G; Shamsudeen, Rahna K; Ramesh, R; Mukundan, T

    2011-08-01

    The acoustic behavior of an acoustically transparent polyurethane and an interpenetrating polymer network of polyurethane with polydimethyl siloxane were studied using dynamic mechanical analysis, finite element modeling, and experimental evaluation of acoustic properties in a water-filled pulse tube setup. Dynamic mechanical measurements in the temperature range -50 °C to +70 °C were carried out, and the data were used for time temperature superposition to generate material behavior at high frequencies. These inputs were used for modeling the acoustic behavior of these materials using ATILA, which is a commercial finite element code, capable of computing transmission and reflection characteristics of materials. From this data, absorption characteristics were computed. The results were compared with the experimental results obtained using a water-filled pulse tube facility.

  3. Optimization of a Biometric System Based on Acoustic Images

    PubMed Central

    Izquierdo Fuente, Alberto; Del Val Puente, Lara; Villacorta Calvo, Juan J.; Raboso Mateos, Mariano

    2014-01-01

    On the basis of an acoustic biometric system that captures 16 acoustic images of a person for 4 frequencies and 4 positions, a study was carried out to improve the performance of the system. On a first stage, an analysis to determine which images provide more information to the system was carried out showing that a set of 12 images allows the system to obtain results that are equivalent to using all of the 16 images. Finally, optimization techniques were used to obtain the set of weights associated with each acoustic image that maximizes the performance of the biometric system. These results improve significantly the performance of the preliminary system, while reducing the time of acquisition and computational burden, since the number of acoustic images was reduced. PMID:24616643

  4. Optimization of a biometric system based on acoustic images.

    PubMed

    Izquierdo Fuente, Alberto; Del Val Puente, Lara; Villacorta Calvo, Juan J; Raboso Mateos, Mariano

    2014-01-01

    On the basis of an acoustic biometric system that captures 16 acoustic images of a person for 4 frequencies and 4 positions, a study was carried out to improve the performance of the system. On a first stage, an analysis to determine which images provide more information to the system was carried out showing that a set of 12 images allows the system to obtain results that are equivalent to using all of the 16 images. Finally, optimization techniques were used to obtain the set of weights associated with each acoustic image that maximizes the performance of the biometric system. These results improve significantly the performance of the preliminary system, while reducing the time of acquisition and computational burden, since the number of acoustic images was reduced.

  5. Multicolor Holography With Phase Shifting

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.

    1996-01-01

    Prototype apparatus constructed to test feasibility of two-color holographic interferometric scheme in which data for reconstructing holographic wavefront obtained with help of phase-shifting technique. Provides two sets of data needed to solve equations for effects of temperature and concentration. Concept extended to holography at three or more wavelengths to measure three or more phenomena associated with significant variations in index of refraction

  6. Phase-shift coherence holography.

    PubMed

    Naik, Dinesh N; Ezawa, Takahiro; Miyamoto, Yoko; Takeda, Mitsuo

    2010-05-15

    We propose and experimentally demonstrate a new reconstruction scheme for coherence holography using computer-generated phase-shift coherence holograms. A 3D object encoded into the spatial coherence function is reconstructed directly from a set of incoherently illuminated computer-generated holograms with numerically introduced phase shifts. Although a rotating ground glass is used to introduce spatially incoherent illumination, the phase-shifting portion of the system is simple and free from mechanically moving components.

  7. Multicolor holography: a comparative study

    NASA Astrophysics Data System (ADS)

    Oliveira, Rosa M.; Bernardo, Luis M.; Pinto, Joao L.

    2000-10-01

    A multicolor holography study case will be presented with emphasis on color control in different silver-halide materials. It has been systematized in order to compare the results obtained with Agfa 8E 75HD to those with Slavich PFG-01. Some experiments were made and the emulsion was manipulated before exposure to achieve high quality multicolored white light reflection holograms. This work has therefore been developed in order to obtain the various colors in a very well controlled way.

  8. Acoustic-optical imaging without immersion

    NASA Technical Reports Server (NTRS)

    Liu, H.

    1979-01-01

    System using membraneous end wall of Bragg cell to separate test specimen from acoustic transmission medium, operates in real time and uses readily available optical components. System can be easily set up and maintained by people with little or no training in holography.

  9. Precise rainbow trapping for low-frequency acoustic waves with micro Mie resonance-based structures

    NASA Astrophysics Data System (ADS)

    Zhou, Chen; Yuan, Baoguo; Cheng, Ying; Liu, Xiaojun

    2016-02-01

    We have realized the acoustic rainbow trapping in the low frequency region (200-500 Hz) through micro Mie resonance-based structures. The structure has eight channels with a high refractive index obtained by coiling space, that can excite strong interactions with incident waves and support various orders of multipoles due to the Mie resonances of the microstructure. By utilizing the structure, the precise spatial modulation of the acoustic wave is demonstrated both theoretically and experimentally. The effect of trapping broadband acoustic waves and spatially separating different frequency components are ascribed to the monopolar Mie resonances of the structures. The trapping frequency is derived and the trapping positions can be tuned arbitrarily. With enhanced wave-structure interactions and tailored frequency responses, such micro structures show precise spectral-spatial control of acoustic waves and open a diverse venue for high performance acoustic wave detection, sensing, filtering, and a nondestructive test.

  10. A tunable acoustic barrier based on periodic arrays of subwavelength slits

    NASA Astrophysics Data System (ADS)

    Rubio, Constanza; Uris, Antonio; Candelas, Pilar; Belmar, Francisco; Gomez-Lozano, Vicente

    2015-05-01

    The most usual method to reduce undesirable enviromental noise levels during its transmission is the use of acoustic barriers. A novel type of acoustic barrier based on sound transmission through subwavelength slits is presented. This system consists of two rows of periodic repetition of vertical rigid pickets separated by a slit of subwavelength width and with a misalignment between them. Here, both the experimental and the numerical analyses are presented. The acoustic barrier proposed can be easily built and is frequency tunable. The results demonstrated that the proposed barrier can be tuned to mitigate a band noise without excesive barrier thickness. The use of this system as an environmental acoustic barrier has certain advantages with regard to the ones currently used both from the constructive and the acoustical point of view.

  11. An Analysis of Consolidation Grouting Effect of Bedrock Based on its Acoustic Velocity Increase

    NASA Astrophysics Data System (ADS)

    Chen, Ming; Lu, Wen-bo; Zhang, Wen-ju; Yan, Peng; Zhou, Chuang-bing

    2015-05-01

    Acoustic velocity is an important parameter to evaluate the mechanical properties of fractured rock masses. Based on the in situ acoustic velocity measurement data of ~20 hydropower stations in China, we assessed the acoustic velocity increase of rock masses as a result of consolidation grouting in different geological conditions, such as fault sites, weathered areas and excavation-induced damage zones. We established an empirical relationship between the acoustic velocity of rock masses before and after consolidation grouting, and examined the correlation between acoustic velocity and deformation modulus. A case study is presented about a foundation consolidation grouting project for an intake tower of Pubugou Hydropower Station. The results show that different types of rock masses possess distinct ranges for resultant acoustic velocity increase by consolidation grouting. Under a confidence interval of 95 %, the ranges of the increasing rate of acoustic velocity in a faulted zone, weathered zone, and excavation-induced damage zone are observed to be 12.7-43.1, 12.3-31.2, and 6.9-14.5 %, respectively. The acoustic velocity before grouting and its increasing rate can be used to predict the effectiveness of consolidation grouting.

  12. Seismic wave detection system based on fully distributed acoustic sensing

    NASA Astrophysics Data System (ADS)

    Jiang, Yue; Xu, Tuanwei; Feng, Shengwen; Huang, Jianfen; Yang, Yang; Guo, Gaoran; Li, Fang

    2016-11-01

    This paper presents a seismic wave detection system based on fully distributed acoustic sensing. Combined with Φ- OTDR and PGC demodulation technology, the system can detect and acquire seismic wave in real time. The system has a frequency response of 3.05 dB from 5 Hz to 1 kHz, whose sampling interval of each channel of 1 meter on total sensing distance up to 10 km. By comparing with the geophone in laboratory, the data show that in the time domain and frequency domain, two waveforms coincide consistently, and the correlation coefficient could be larger than 0.98. Through the analysis of the data of the array experiment and the oil well experiment, DAS system shows a consistent time domain and frequency domain response and a clearer trail of seismic wave signal as well as a higher signal-noise rate which indicate that the system we proposed is expected to become the next generation of seismic exploration equipment.

  13. Combined Helmholtz equation-least squares method for reconstructing acoustic radiation from arbitrarily shaped objects.

    PubMed

    Wu, Sean F; Zhao, Xiang

    2002-07-01

    A combined Helmholtz equation-least squares (CHELS) method is developed for reconstructing acoustic radiation from an arbitrary object. This method combines the advantages of both the HELS method and the Helmholtz integral theory based near-field acoustic holography (NAH). As such it allows for reconstruction of the acoustic field radiated from an arbitrary object with relatively few measurements, thus significantly enhancing the reconstruction efficiency. The first step in the CHELS method is to establish the HELS formulations based on a finite number of acoustic pressure measurements taken on or beyond a hypothetical spherical surface that encloses the object under consideration. Next enough field acoustic pressures are generated using the HELS formulations and taken as the input to the Helmholtz integral formulations implemented through the boundary element method (BEM). The acoustic pressure and normal component of the velocity at the discretized nodes on the surface are then determined by solving two matrix equations using singular value decomposition (SVD) and regularization techniques. Also presented are in-depth analyses of the advantages and limitations of the CHELS method. Examples of reconstructing acoustic radiation from separable and nonseparable surfaces are demonstrated.

  14. Evaluation of Conoscopic Holography for Estimating Tumor Resection Cavities in Model-Based Image-Guided Neurosurgery

    PubMed Central

    Sun, Kay; Pheiffer, Thomas S.; Rucker, D. Caleb; Sills, Allen K.; Thompson, Reid C.; Miga, Michael I.

    2014-01-01

    Surgical navigation relies on accurately mapping the intraoperative state of the patient to models derived from preoperative images. In image-guided neurosurgery, soft tissue deformations are common and have been shown to compromise the accuracy of guidance systems. In lieu of whole-brain intraoperative imaging, some advocate the use of intraoperatively acquired sparse data from laser-range scans, ultrasound imaging, or stereo reconstruction coupled with a computational model to drive subsurface deformations. Some authors have reported on compensating for brain sag, swelling, retraction, and the application of pharmaceuticals such as mannitol with these models. To date, strategies for modeling tissue resection have been limited. In this paper, we report our experiences with a novel digitization approach, called a conoprobe, to document tissue resection cavities and assess the impact of resection on model-based guidance systems. Specifically, the conoprobe was used to digitize the interior of the resection cavity during eight brain tumor resection surgeries and then compared against model prediction results of tumor locations. We should note that no effort was made to incorporate resection into the model but rather the objective was to determine if measurement was possible to study the impact on modeling tissue resection. In addition, the digitized resection cavity was compared with early postoperative MRI scans to determine whether these scans can further inform tissue resection. The results demonstrate benefit in model correction despite not having resection explicitly modeled. However, results also indicate the challenge that resection provides for model-correction approaches. With respect to the digitization technology, it is clear that the conoprobe provides important real-time data regarding resection and adds another dimension to our noncontact instrumentation framework for soft-tissue deformation compensation in guidance systems. PMID:24845293

  15. Adaptive holography for optical sensing applications

    NASA Astrophysics Data System (ADS)

    Residori, S.; Bortolozzo, U.; Peigné, A.; Molin, S.; Nouchi, P.; Dolfi, D.; Huignard, J. P.

    2016-03-01

    Adaptive holography is a promising method for high sensitivity phase modulation measurements in the presence of slow perturbations from the environment. The technique is based on the use of a nonlinear recombining medium, here an optically addressed spatial light modulator specifically realized to operate at 1.55 μm. Owing to the physical mechanisms involved, the interferometer adapts to slow phase variations within a range of 5-10 Hz, thus filtering out low frequency noise while transmitting higher frequency phase modulations. We present the basic principles of the adaptive interferometer and show that it can be used in association with a sensing fiber in order to detect phase modulations. Finally, a phase-OTDR architecture using the adaptive holographic interferometer is presented and shown to allows the detection of localized perturbations along the sensing fiber.

  16. Remote metrology by comparative digital holography

    SciTech Connect

    Baumbach, Torsten; Osten, Wolfgang; Kopylow, Christoph von; Jueptner, Werner

    2006-02-10

    A method for the remote comparison of objects with regard to their shape or response to a load is presented. The method allows interferometric sensitivity for comparing objects with different microstructure. In contrast to the well-known incoherent techniques based on inverse fringe projection this new approach uses the coherent optical wave field of the master object as a mask for the illumination of the sample object. The coherent mask is created by digital holography to allow instant access to the complete optical information of the master object at any place desired. The mask is reconstructed by a spatial light modulator (SLM). The optical reconstruction of digital holograms with SLM technology allows modification of reconstructed wavefronts with respect to improvement of image quality, the skilled introduction of additional information about the object (augmented reality), and the alignment of the master and test object.

  17. Microcrack Identification in Cement-Based Materials Using Nonlinear Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Chen, X. J.; Kim, J.-Y.; Qu, J.; Kurtis, K. E.; Wu, S. C.; Jacobs, L. J.

    2007-03-01

    This paper presents results from tests that use nonlinear acoustic waves to distinguish microcracks in cement-based materials. Portland cement mortar samples prepared with alkali-reactive aggregate were exposed to an aggressive environment to induce cracking were compared to control samples, of the same composition, but which were not exposed to aggressive conditions. Two nonlinear ultrasonic methods were used to characterize the samples, with the aim of identifying the time and extent of microcracking; these techniques were a nonlinear acoustical modulation (NAM) method and a harmonic amplitude relation (HAR) method. These nonlinear acoustic results show that both methods can distinguish damaged samples from undamaged ones, demonstrating the potential of nonlinear acoustic waves to provide a quantitative evaluation of the deterioration of cement-based materials.

  18. Accurate recovery of articulator positions from acoustics: New conclusions based on human data

    SciTech Connect

    Hogden, J.; Lofqvist, A.; Gracco, V.; Zlokarnik, I.; Rubin, P.; Saltzman, E.

    1996-09-01

    Vocal tract models are often used to study the problem of mapping from the acoustic transfer function to the vocal tract area function (inverse mapping). Unfortunately, results based on vocal tract models are strongly affected by the assumptions underlying the models. In this study, the mapping from acoustics (digitized speech samples) to articulation (measurements of the positions of receiver coils placed on the tongue, jaw, and lips) is examined using human data from a single speaker: Simultaneous acoustic and articulator measurements made for vowel-to-vowel transitions, /g/ closures, and transitions into and out of /g/ closures. Articulator positions were measured using an EMMA system to track coils placed on the lips, jaw, and tongue. Using these data, look-up tables were created that allow articulator positions to be estimated from acoustic signals. On a data set not used for making look-up tables, correlations between estimated and actual coil positions of around 94{percent} and root-mean-squared errors around 2 mm are common for coils on the tongue. An error source evaluation shows that estimating articulator positions from quantized acoustics gives root-mean-squared errors that are typically less than 1 mm greater than the errors that would be obtained from quantizing the articulator positions themselves. This study agrees with and extends previous studies of human data by showing that for the data studied, speech acoustics can be used to accurately recover articulator positions. {copyright} {ital 1996 Acoustical Society of America.}

  19. Development and calibration of acoustic video camera system for moving vehicles

    NASA Astrophysics Data System (ADS)

    Yang, Diange; Wang, Ziteng; Li, Bing; Lian, Xiaomin

    2011-05-01

    In this paper, a new acoustic video camera system is developed and its calibration method is established. This system is built based on binocular vision and acoustical holography technology. With binocular vision method, the spatial distance between the microphone array and the moving vehicles is obtained, and the sound reconstruction plane can be established closely to the moving vehicle surface automatically. Then the sound video is regenerated closely to the moving vehicles accurately by acoustic holography method. With this system, the moving and stationary sound sources are treated differently and automatically, which makes the sound visualization of moving vehicles much quicker, more intuitively, and accurately. To verify this system, experiments for a stationary speaker and a non-stationary speaker are carried out. Further verification experiments for outdoor moving vehicle are also conducted. Successful video visualization results not only confirm the validity of the system but also suggest that this system can be a potential useful tool in vehicle's noise identification because it allows the users to find out the noise sources by the videos easily. We believe the newly developed system will be of great potential in moving vehicles' noise identification and control.

  20. Fish Acoustics: Physics-Based Modeling and Measurement

    DTIC Science & Technology

    2011-01-01

    physical scattering mechanisms. To demonstrate this point, the target strength of a canonical gas-filled sphere is computed using a standard...high-frequency sound scattering by swimbladdered fish,” Journal of the Acoustical Society of America, Vol. 78, pp. 688-700 (1985). 9. Gauss , R. C

  1. Aesthetics and representation in holography

    NASA Astrophysics Data System (ADS)

    Kac, Eduardo

    1995-02-01

    Every medium has a code, a set of rules or conventions according to which determined elements are organized into a signifying system. The English language is a code as is perspective in painting and photography. In the first case, the elements are phonemes organized into words and sentences according to a social convention: the syntax of English. In the second case, the elements are dots and lines organized into pictures according to a geometric method. An artist or movement can break the conventions of the medium, as has done Cezanne with painting, Moholy-Nagy with photography and cummings with the English idiom in poetry, and create new elements and rules for combining them. If this is done, the level of predictability (or conventionality) is lowered and unpredictability is increased -- becoming more difficult for the immediate audience to understand it. But once these new rules are learned and the ideas behind them widely understood, the level of unpredictability is lowered and they become new conventions that can be accepted by the audience. Holographic artists exploring the medium -- as opposed to advertisers using holography, who favor a high level of predictability -- are breaking several visual and cultural conventions. As a matter of fact, holography is so new that many questions are left open about the nature of the medium. Therefore, any attempt to clarify the issues raised by holography on a cultural level has a prospective (and not conclusive) tone, concentrating more thoroughly on general points and on the promise of its potentialities than on the records of its historical achievements so far.

  2. Compressive holography with a single-pixel detector.

    PubMed

    Clemente, Pere; Durán, Vicente; Tajahuerce, Enrique; Andrés, Pedro; Climent, Vicent; Lancis, Jesús

    2013-07-15

    This Letter develops a framework for digital holography at optical wavelengths by merging phase-shifting interferometry with single-pixel optical imaging based on compressive sensing. The field diffracted by an input object is sampled by Hadamard patterns with a liquid crystal spatial light modulator. The concept of a single-pixel camera is then adapted to perform interferometric imaging of the sampled diffraction pattern by using a Mach-Zehnder interferometer. Phase-shifting techniques together with the application of a backward light propagation algorithm allow the complex amplitude of the object under scrutiny to be resolved. A proof-of-concept experiment evaluating the phase distribution of an ophthalmic lens with compressive phase-shifting holography is provided.

  3. Resampling masks for phase-shifting digital holography

    NASA Astrophysics Data System (ADS)

    Zhang, Wenhui; Cao, Liangcai; Zhang, Hao; Zong, Song; Jin, Guofan

    2016-10-01

    Holographic imaging is degraded severely by the speckle or incoherent noise. In this work, resampling mask method based on phase-shifting digital holography is proposed to reduce the reconstruction noise. The zero-order and the conjugate term of the hologram can be eliminated with four-step phase-shifting digital holography (PSDH). The complex amplitude of the object after propagation can be calculated by the phase-shifting algorithm. A phase-only spatial light modulator is used to realize PSDH in the experiment. The complex amplitude is encoded into several parts by resampling masks. A high quality reconstruction image with low noise is achieved through the superposition of the individually reconstruction of coded complex amplitudes. The experiment data go well with the asymptotic function. This method can be used for digital holographic imaging of the biological samples and microstructures. Experimental results prove the feasibility of this proposed method.

  4. Geometric Modeling With Image Plane Integral (IPI) Holography

    NASA Astrophysics Data System (ADS)

    Lacey, D. C. L.

    1984-10-01

    Holography has long been considered to be an ideal method of visually presenting three-dimensional data which has been either experimentally acquired or mathematically calculated with a preconceived form in mind. Unfortunately, holograms have not had the image quality and accuracy to gain scientific acceptability outside the field of interferometric analysis. This paper will describe the use of an advanced composite holographic technique to give a clear, autostereoscopic image of a computer designed automotive part and a computer graphics concept of a molecule. The holograms were manufactured using Image Plane Integral (IPI) holography on an Argon laser printer designed and built by the author. The final holograms exhibited bright, achromatic, real images with high resolution and a minimum amount of controllable distortion. Additionally, because the IPI method uses a 35mm microfilmstrip for input, it could be universally applied as a hard copy format for presentation of almost any type of three-dimensional data base.

  5. Frequency analysis of digital holography

    NASA Astrophysics Data System (ADS)

    Kreis, Thomas M.

    2002-04-01

    A coherent optical imaging system consisting of recording a digital hologram by a CCD array and numerical reconstruction of the complex wave field in a computer is subjected to a frequency analysis. This analysis recognizes Fresnel and lensless Fourier transform holography; collimated and divergent reference waves; as well as the real image, the virtual image, and the dc term. The influences of finite sampling and the fill factor of the CCD pixels are examined. The impulse response of the system is a shifted Fraunhofer diffraction pattern of the aperture defined by the CCD. A fill factor below unity leads to a contrast decrease, which is quantitatively described in the modulation transfer function.

  6. 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.

  7. The microwave holography system for the Sardinia Radio Telescope

    NASA Astrophysics Data System (ADS)

    Serra, G.; Bolli, P.; Busonera, G.; Pisanu, T.; Poppi, S.; Gaudiomonte, F.; Zacchiroli, G.; Roda, J.; Morsiani, M.; López-Pérez, J. A.

    2012-09-01

    Microwave holography is a well-established technique for mapping surface errors of large reflector antennas, particularly those designed to operate at high frequencies. We present here a holography system based on the interferometric method for mapping the primary reflector surface of the Sardinia Radio Telescope (SRT). SRT is a new 64-m-diameter antenna located in Sardinia, Italy, equipped with an active surface and designed to operate up to 115 GHz. The system consists mainly of two radio frequency low-noise coherent channels, designed to receive Ku-band digital TV signals from geostationary satellites. Two commercial prime focus low-noise block converters are installed on the radio telescope under test and on a small reference antenna, respectively. Then the signals are amplified, filtered and downconverted to baseband. An innovative digital back-end based on FPGA technology has been implemented to digitize two 5 MHz-band signals and calculate their cross-correlation in real-time. This is carried out by using a 16-bit resolution ADCs and a FPGA reaching very large amplitude dynamic range and reducing post-processing time. The final holography data analysis is performed by CLIC data reduction software developed within the Institut de Radioastronomie Millimétrique (IRAM, Grenoble, France). The system was successfully tested during several holography measurement campaigns, recently performed at the Medicina 32-m radio telescope. Two 65-by-65 maps, using an on-the-fly raster scan with on-source phase calibration, were performed pointing the radio telescope at 38 degrees elevation towards EUTELSAT 7A satellite. The high SNR (greater than 60 dB) and the good phase stability led to get an accuracy on the surface error maps better than 150 μm RMS.

  8. Computer Generated Holography with Intensity-Graded Patterns

    PubMed Central

    Conti, Rossella; Assayag, Osnath; de Sars, Vincent; Guillon, Marc; Emiliani, Valentina

    2016-01-01

    Computer Generated Holography achieves patterned illumination at the sample plane through phase modulation of the laser beam at the objective back aperture. This is obtained by using liquid crystal-based spatial light modulators (LC-SLMs), which modulate the spatial phase of the incident laser beam. A variety of algorithms is employed to calculate the phase modulation masks addressed to the LC-SLM. These algorithms range from simple gratings-and-lenses to generate multiple diffraction-limited spots, to iterative Fourier-transform algorithms capable of generating arbitrary illumination shapes perfectly tailored on the base of the target contour. Applications for holographic light patterning include multi-trap optical tweezers, patterned voltage imaging and optical control of neuronal excitation using uncaging or optogenetics. These past implementations of computer generated holography used binary input profile to generate binary light distribution at the sample plane. Here we demonstrate that using graded input sources, enables generating intensity graded light patterns and extend the range of application of holographic light illumination. At first, we use intensity-graded holograms to compensate for LC-SLM position dependent diffraction efficiency or sample fluorescence inhomogeneity. Finally we show that intensity-graded holography can be used to equalize photo evoked currents from cells expressing different levels of chanelrhodopsin2 (ChR2), one of the most commonly used optogenetics light gated channels, taking into account the non-linear dependence of channel opening on incident light. PMID:27799896

  9. Model-based passive acoustic tracking of sperm whale foraging behavior in the Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Tiemann, Christopher; Thode, Aaron; Straley, Jan; Folkert, Kendall; O'Connell, Victoria

    2005-09-01

    In 2004, the Southeast Alaska Sperm Whale Avoidance Project (SEASWAP) introduced the use of passive acoustics to help monitor the behavior of sperm whales depredating longline fishing operations. Acoustic data from autonomous recorders mounted on longlines provide the opportunity to demonstrate a tracking algorithm based on acoustic propagation modeling while providing insight into whales' foraging behavior. With knowledge of azimuthally dependent bathymetry, a 3D track of whale motion can be obtained using data from just one hydrophone by exploiting multipath arrival information from recorded sperm whale clicks. The evolution of multipath arrival patterns is matched to range-, depth-, and azimuth-dependent modeled arrival patterns to generate an estimate of whale motion. This technique does not require acoustic ray identification (i.e., direct path, surface reflected, etc.) while still utilizing individual ray arrival information, and it can also account for all waveguide propagation physics such as interaction with range-dependent bathymetry and ray refraction.

  10. Development of an Acoustic Levitation Linear Transportation System Based on a Ring-type Structure.

    PubMed

    Thomas, Gilles; Andrade, Marco Aurelio; Adamowski, Julio; Silva, Emilio

    2017-02-23

    A linear acoustic levitation transportation system based on a ring-type vibrator is presented. The system is composed by two 21 kHz Langevin transducers connected to a ring-shaped structure formed by two semicircular sections and two flat plates. In this system, a flexural standing wave is generated along the ring structure, producing an acoustic standing wave between the vibrating ring and a plane reflector located at a distance of approximately a half wavelength from the ring. The acoustic standing wave in air has a series of pressure nodes, where small particles can be levitated and transported. The ring-type transportation system was designed and analyzed by using the Finite Element Method (FEM). Additionally, a prototype was built and the acoustic levitation and transport of a small polystyrene particle was demonstrated.

  11. Four-dimensional key design in amplitude, phase, polarization and distance for optical encryption based on polarization digital holography and QR code.

    PubMed

    Lin, Chao; Shen, Xueju; Li, Baochen

    2014-08-25

    We demonstrate that all parameters of optical lightwave can be simultaneously designed as keys in security system. This multi-dimensional property of key can significantly enlarge the key space and further enhance the security level of the system. The single-shot off-axis digital holography with orthogonal polarized reference waves is employed to perform polarization state recording on object wave. Two pieces of polarization holograms are calculated and fabricated to be arranged in reference arms to generate random amplitude and phase distribution respectively. When reconstruction, original information which is represented with QR code can be retrieved using Fresnel diffraction with decryption keys and read out noise-free. Numerical simulation results for this cryptosystem are presented. An analysis on the key sensitivity and fault tolerance properties are also provided.

  12. High-spatial-resolution sub-surface imaging using a laser-based acoustic microscopy technique.

    PubMed

    Balogun, Oluwaseyi; Cole, Garrett D; Huber, Robert; Chinn, Diane; Murray, Todd W; Spicer, James B

    2011-01-01

    Scanning acoustic microscopy techniques operating at frequencies in the gigahertz range are suitable for the elastic characterization and interior imaging of solid media with micrometer-scale spatial resolution. Acoustic wave propagation at these frequencies is strongly limited by energy losses, particularly from attenuation in the coupling media used to transmit ultrasound to a specimen, leading to a decrease in the depth in a specimen that can be interrogated. In this work, a laser-based acoustic microscopy technique is presented that uses a pulsed laser source for the generation of broadband acoustic waves and an optical interferometer for detection. The use of a 900-ps microchip pulsed laser facilitates the generation of acoustic waves with frequencies extending up to 1 GHz which allows for the resolution of micrometer-scale features in a specimen. Furthermore, the combination of optical generation and detection approaches eliminates the use of an ultrasonic coupling medium, and allows for elastic characterization and interior imaging at penetration depths on the order of several hundred micrometers. Experimental results illustrating the use of the laser-based acoustic microscopy technique for imaging micrometer-scale subsurface geometrical features in a 70-μm-thick single-crystal silicon wafer with a (100) orientation are presented.

  13. Holograms for acoustics

    NASA Astrophysics Data System (ADS)

    Melde, Kai; Mark, Andrew G.; Qiu, Tian; Fischer, Peer

    2016-09-01

    Holographic techniques are fundamental to applications such as volumetric displays, high-density data storage and optical tweezers that require spatial control of intricate optical or acoustic fields within a three-dimensional volume. The basis of holography is spatial storage of the phase and/or amplitude profile of the desired wavefront in a manner that allows that wavefront to be reconstructed by interference when the hologram is illuminated with a suitable coherent source. Modern computer-generated holography skips the process of recording a hologram from a physical scene, and instead calculates the required phase profile before rendering it for reconstruction. In ultrasound applications, the phase profile is typically generated by discrete and independently driven ultrasound sources; however, these can only be used in small numbers, which limits the complexity or degrees of freedom that can be attained in the wavefront. Here we introduce monolithic acoustic holograms, which can reconstruct diffraction-limited acoustic pressure fields and thus arbitrary ultrasound beams. We use rapid fabrication to craft the holograms and achieve reconstruction degrees of freedom two orders of magnitude higher than commercial phased array sources. The technique is inexpensive, appropriate for both transmission and reflection elements, and scales well to higher information content, larger aperture size and higher power. The complex three-dimensional pressure and phase distributions produced by these acoustic holograms allow us to demonstrate new approaches to controlled ultrasonic manipulation of solids in water, and of liquids and solids in air. We expect that acoustic holograms will enable new capabilities in beam-steering and the contactless transfer of power, improve medical imaging, and drive new applications of ultrasound.

  14. A scanning acoustic microscope based on picosecond ultrasonics.

    PubMed

    Che, S; Guduru, P R; Nurmikko, A V; Maris, H J

    2015-02-01

    We report on the development of a new type of scanning acoustic microscope. We use a femtosecond light pulse to generate a short sound pulse, and then focus this sound onto the sample by means of a specially designed and microfabricated acoustic lens of radius a few microns. The sound travels to the sample through a thin layer of water. The sound reflected from the sample is collected by the lens and then passes through a monolithically integrated optical resonant cavity. The induced change in the properties of this cavity are measured using a time-delayed probe light pulse. We describe some of the challenges involved in the construction and operation of this high-precision metrology apparatus and present some preliminary results.

  15. Experimentally-Based Ocean Acoustic Propagation and Coherence Studies

    DTIC Science & Technology

    2012-01-01

    water, where sound is highly bottom interacting, and the temperate deep -ocean sound channel. Acoustic field fluctuations have time scales varying from...that has been observed in both shallow and deep regimes. For shallow water, we seek to understand the mean and variability of transmission loss and...phase at frequencies from 50 to 3000 Hz. For the deep -ocean sound channel, the objective is to better characterize coupled-mode propagation at 50 to 100

  16. Experimentally-Based Ocean Acoustic Propagation and Coherence Studies

    DTIC Science & Technology

    2011-09-01

    temperate deep -ocean sound channel. Reliable predictions of temporal and spatial variability of received underwater sound can improve processing and...3000 Hz. For the deep -ocean sound channel, the objective is to better characterize coupled-mode propagation at 50 to 100 Hz, which may have some...Sea spring 2007 ONR/Taiwan NLIWI acoustics experiment [Reeder et al., 2010], and the Shelfbreak PRIMER study. For deep -water studies, data are from the

  17. Sonobuoy-Based Acoustic Characterization of Shallow-Water Environments

    DTIC Science & Technology

    2014-09-30

    obtaining the laterally varying, acoustic properties of the waveguide [2-7]. The experimental configuration consists of a moored, drifting , or towed...source, with GPS navigation, transmitting signals to a field of several freely drifting buoys, each containing a hydrophone, GPS navigation, and radio...buoy, thereby enabling the determination of the positions of the buoys relative to the ship with submeter accuracy [8,9]. In this manner, the drifting

  18. Resolution factors in edgeline holography.

    PubMed

    Trolinger, J D; Gee, T H

    1971-06-01

    When an in-line Fresnel hologram of an object such as a projectile in flight is made, the reconstruction comprises an image of the outside edge of the object superimposed upon a Fresnel diffraction pattern of the edge and an unmodulated portion of the reconstruction beam. When the reconstructed image is bandpass filtered, the only remaining significant contribution is that of a diffraction pattern which is symmetrical about an edgeline gaussian image of the object. The present paper discusses the application of this type of holography in accurately locating the edge of a large dynamic object, the position of which is not accurately known in any dimension. A theoretical and experimental analysis was performed to study the effects of motion, hologram size, film type, and practical limitations upon the attainable resolution in the reconstructed image. The bandlimiting effect of motion is used to relate the motion effected resolution limit of holography to that of photography. The study shows that an edgeline can be accurately located even at high velocity normal to the edge.

  19. New acoustical technology of sound absorption based on reverse horn

    NASA Astrophysics Data System (ADS)

    Zhang, Yong Yan; Wu, Jiu Hui; Cao, Song Hua; Cao, Pei; Zhao, Zi Ting

    2016-12-01

    In this paper, a novel reverse horn’s sound-absorption mechanism and acoustic energy focusing mechanism for low-frequency broadband are presented. Due to the alternation of the reverse horn’s thickness, the amplitude of the acoustic pressure propagated in the structure changes, which results in growing energy focused in the edge and in the reverse horn’s tip when the characteristic length is equal to or less than a wavelength and the incident wave is compressed. There are two kinds of methods adopted to realize energy dissipation. On the one hand, sound-absorbing materials are added in incident direction in order to overcome the badness of the reverse horn’s absorption in high frequency and improve the overall high-frequency and low-frequency sound-absorption coefficients; on the other hand, adding mass and film in its tip could result in mechanical energy converting into heat energy due to the coupled vibration of mass and the film. Thus, the reverse horn with film in the tip could realize better sound absorption for low-frequency broadband. These excellent properties could have potential applications in the one-dimensional absorption wedge and for the control of acoustic wave.

  20. Surface acoustic wave gas sensor based on film conductivity changes

    NASA Astrophysics Data System (ADS)

    Ricco, A. J.; Martin, S. J.; Zipperian, T. E.

    1985-12-01

    The first surfce acoustic wave (SAW) sensor that functions via changes in conductivity of a thin surface film is reported. A lead phthalocyanine (PbPc) thin film is deposted on the acoustic progagation path of a LiNbO3 SAW delay line, which serves as the feedback element of an oscillator circuit. Reaction with strongly oxidizing gases, in particular NO2, increases the conductivity of the PbPc film. Acoustoelectric coupling of the traveling electric potential wave associated with the SAW-to-charge carriers in the PbPc film slows the acoustic wave velocity, altering the oscillation frequency of the circuit. This sensor is about 1000 times more sensitive, in terms of the number of NO2 molecules that can be detected (10 to the 16th molecules/cu cm of PbPc film), than an identical SAW sensor functioning via mass loading would be. Sensitivity to a few ppm of NO2 in N2 has been demonstrated.

  1. Surface acoustic wave gas sensor based on film conductivity changes

    NASA Astrophysics Data System (ADS)

    Ricco, A. J.; Martin, S. J.; Zipperian, T. E.

    The first surface acoustic wave (SAW) sensor that functions via changes in conductivity of a thin surface film is reported. A lead phthalocyanine (PbPc) thin film is deposited on the acoustic propagation path of a LiNbO3 SAW delay line, which serves as the feedback element of an oscillator circuit. Reaction with strongly oxidizing gases, in particular NO2, increases the conductivity of the PbPc film. Acoustoelectic coupling of the traveling electric potential wave associated with the SAW-to-charge carriers in the PbPc film slows the acoustic wave velocity, altering the oscillation frequency of the circuit. This sensor is about 1000 times more sensitive, in terms of the number of NO2 molecules that can be detected (10 to the 16th molecules/cu cm of PbPc film), than an identical SAW sensor functioning via mass loading would be. Sensitivity to a few ppm of NO2 in Ne was demonstrated.

  2. 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.

  3. Ultra-realistic imaging: a new beginning for display holography

    NASA Astrophysics Data System (ADS)

    Bjelkhagen, Hans I.; Brotherton-Ratcliffe, David

    2014-02-01

    Recent improvements in key foundation technologies are set to potentially transform the field of Display Holography. In particular new recording systems, based on recent DPSS and semiconductor lasers combined with novel recording materials and processing, have now demonstrated full-color analogue holograms of both lower noise and higher spectral accuracy. Progress in illumination technology is leading to a further major reduction in display noise and to a significant increase of the clear image depth and brightness of such holograms. So too, recent progress in 1-step Direct-Write Digital Holography (DWDH) now opens the way to the creation of High Virtual Volume Displays (HVV) - large format full-parallax DWDH reflection holograms having fundamentally larger clear image depths. In a certain fashion HVV displays can be thought of as providing a high quality full-color digital equivalent to the large-format laser-illuminated transmission holograms of the sixties and seventies. Back then, the advent of such holograms led to much optimism for display holography in the market. However, problems with laser illumination, their monochromatic analogue nature and image noise are well cited as being responsible for their failure in reality. Is there reason for believing that the latest technology improvements will make the mark this time around? This paper argues that indeed there is.

  4. Time-instant sampling based encoding of time-varying acoustic spectrum

    NASA Astrophysics Data System (ADS)

    Sharma, Neeraj Kumar

    2015-12-01

    The inner ear has been shown to characterize an acoustic stimuli by transducing fluid motion in the inner ear to mechanical bending of stereocilia on the inner hair cells (IHCs). The excitation motion/energy transferred to an IHC is dependent on the frequency spectrum of the acoustic stimuli, and the spatial location of the IHC along the length of the basilar membrane (BM). Subsequently, the afferent auditory nerve fiber (ANF) bundle samples the encoded waveform in the IHCs by synapsing with them. In this work we focus on sampling of information by afferent ANFs from the IHCs, and show computationally that sampling at specific time instants is sufficient for decoding of time-varying acoustic spectrum embedded in the acoustic stimuli. The approach is based on sampling the signal at its zero-crossings and higher-order derivative zero-crossings. We show results of the approach on time-varying acoustic spectrum estimation from cricket call signal recording. The framework gives a time-domain and non-spatial processing perspective to auditory signal processing. The approach works on the full band signal, and is devoid of modeling any bandpass filtering mimicking the BM action. Instead, we motivate the approach from the perspective of event-triggered sampling by afferent ANFs on the stimuli encoded in the IHCs. Though the approach gives acoustic spectrum estimation but it is shallow on its complete understanding for plausible bio-mechanical replication with current mammalian auditory mechanics insights.

  5. Design of acoustic logging signal source of imitation based on field programmable gate array

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Ju, X. D.; Lu, J. Q.; Men, B. Y.

    2014-08-01

    An acoustic logging signal source of imitation is designed and realized, based on the Field Programmable Gate Array (FPGA), to improve the efficiency of examining and repairing acoustic logging tools during research and field application, and to inspect and verify acoustic receiving circuits and corresponding algorithms. The design of this signal source contains hardware design and software design,and the hardware design uses an FPGA as the control core. Four signals are made first by reading the Random Access Memory (RAM) data which are inside the FPGA, then dealing with the data by digital to analog conversion, amplification, smoothing and so on. Software design uses VHDL, a kind of hardware description language, to program the FPGA. Experiments illustrate that the ratio of signal to noise for the signal source is high, the waveforms are stable, and also its functions of amplitude adjustment, frequency adjustment and delay adjustment are in accord with the characteristics of real acoustic logging waveforms. These adjustments can be used to imitate influences on sonic logging received waveforms caused by many kinds of factors such as spacing and span of acoustic tools, sonic speeds of different layers and fluids, and acoustic attenuations of different cementation planes.

  6. A high-throughput standing surface acoustic wave (SSAW)-based cell sorter

    PubMed Central

    Li, Peng; Mao, Zhangming; Huang, Po-Hsun; Rufo, Joseph; Guo, Feng; Wang, Lin; McCoy, J. Philip; Levine, Stewart J.; Huang, Tony Jun

    2015-01-01

    Acoustic-based fluorescence activated cell sorters (FACS) have drawn increased attention in recent years due to their versatility, high biocompatibility, high controllability, and simple design. However, the sorting throughput for existing acoustic cell sorters is far from optimum for practical applications. Here we report a high-throughput cell sorting method based on standing surface acoustic waves (SSAWs). We utilized a pair of focused interdigital transducers (FIDTs) to generate SSAW with high resolution and high energy efficiency. As a result, the sorting throughput is improved significantly from conventional acoustic-based cell sorting methods. We demonstrated the successful sorting of 10 μm polystyrene particles with a minimum actuation time of 72 μs, which translates to a potential sorting rate of more than 13,800 events/s. Without using a cell-detection unit, we were able to demonstrate an actual sorting throughput of 3,300 events/s. Our sorting method can be conveniently integrated with upstream detection units, and it represents an important development towards a functional acoustic-based FACS system. PMID:26289231

  7. Present State Iof Holography In Japan

    NASA Astrophysics Data System (ADS)

    Suzuki, Masane; Hayashi, Yuzo; Yamamoto, Y.

    1983-07-01

    In 1948,Dr. Dennis Gabor introduced the theory of holography as "the optical recording of the object wave formed by the resulting interference pattern of two mutually coherent, component light beams." Through the studies of enumerous practical applications, the theory of holography was further advanced to be used in conjunction with the laser beam to better serve a more practical minded industry. Such developments were introduced and engineered by Dr. Emmett Leith and Dr. Juris Upatnieks in 1962.

  8. Horizontal-parallax-only electronic holography

    NASA Astrophysics Data System (ADS)

    Poon, T.-C.; Akin, T.; Indebetouw, G.; Kim, T.

    2005-04-01

    The principle of optical scanning holography (OSH) is proposed to acquire horizontal-parallax-only (HPO) holographic information electronically. We first briefly summarize the results of OSH and then discuss how HPO-electronic holographic information can be acquired using OSH. Finally we provide simulations to illustrate and clarify the proposed idea. Although many ideas of HPO-holography have been proposed and studied, to the best of our knowledge, this is the first proposed electronic technique to acquire HPO-holographic information.

  9. Applications of real-time holography

    NASA Astrophysics Data System (ADS)

    Feinberg, J.

    1985-01-01

    Holographic principles are discussed, with a description of the steps of hologram production and reconstruction and the materials used in storage of the images. Real-time holography applications, including photolithography, double-exposure interferometry, time-averaged holography, parallel optical processing, optical phase conjugation, beam steering, and moving holograms, are described in detail. In addition, current areas of active research and some experimental applications are discussed.

  10. Experimental observation of acoustic emissions generated by a pulsed proton beam from a hospital-based clinical cyclotron

    SciTech Connect

    Jones, Kevin C.; Solberg, Timothy D.; Avery, Stephen; Vander Stappen, François; Janssens, Guillaume; Prieels, Damien; Bawiec, Christopher R.; Lewin, Peter A.; Sehgal, Chandra M.

    2015-12-15

    Purpose: To measure the acoustic signal generated by a pulsed proton spill from a hospital-based clinical cyclotron. Methods: An electronic function generator modulated the IBA C230 isochronous cyclotron to create a pulsed proton beam. The acoustic emissions generated by the proton beam were measured in water using a hydrophone. The acoustic measurements were repeated with increasing proton current and increasing distance between detector and beam. Results: The cyclotron generated proton spills with rise times of 18 μs and a maximum measured instantaneous proton current of 790 nA. Acoustic emissions generated by the proton energy deposition were measured to be on the order of mPa. The origin of the acoustic wave was identified as the proton beam based on the correlation between acoustic emission arrival time and distance between the hydrophone and proton beam. The acoustic frequency spectrum peaked at 10 kHz, and the acoustic pressure amplitude increased monotonically with increasing proton current. Conclusions: The authors report the first observation of acoustic emissions generated by a proton beam from a hospital-based clinical cyclotron. When modulated by an electronic function generator, the cyclotron is capable of creating proton spills with fast rise times (18 μs) and high instantaneous currents (790 nA). Measurements of the proton-generated acoustic emissions in a clinical setting may provide a method for in vivo proton range verification and patient monitoring.

  11. Fuel Line Based Acoustic Flame-Out Detection System

    NASA Technical Reports Server (NTRS)

    Puster, Richard L. (Inventor); Franke, John M. (Inventor)

    1997-01-01

    An acoustic flame-out detection system that renders a large high pressure combustor safe in the event of a flame-out and possible explosive reignition. A dynamic pressure transducer is placed in the fuel and detects the stabilizing fuel pressure oscillations, caused by the combustion process. An electric circuit converts the signal from the combustion vortices, and transmitted to the fuel flow to a series of pulses. A missing pulse detector counts the pulses and continuously resets itself. If three consecutive pulses are missing, the circuit closes the fuel valve. With fuel denied the combustor is shut down or restarted under controlled conditions.

  12. Surface acoustic wave vapor sensors based on resonator devices

    NASA Astrophysics Data System (ADS)

    Grate, Jay W.; Klusty, Mark

    1991-05-01

    Surface acoustic wave (SAW) devices fabricated in the resonator configuration have been used as organic vapor sensors and compared with delay line devices more commonly used. The experimentally determined mass sensitivities of 200, 300, and 400 MHz resonators and 158 MHz delay lines coated with Langmuir-Blodgett films of poly(vinyl tetradecanal) are in excellent agreement with theoretical predictions. The response of LB- and spray-coated sensors to various organic vapors were determined, and scaling laws for mass sensitivities, vapor sensitivities, and detection limits are discussed. The 200 MHz resonators provide the lowest noise levels and detection limits of all the devices examined.

  13. Acoustic Disturbance of Ionospheric Plasma by a Ground-Based Radiator

    NASA Astrophysics Data System (ADS)

    Koshovyi, V. V.; Soroka, S. O.

    The authors present the first results of experimental testing of the possibilities of acoustic disturbance of the ionosphere by a controllable ground-based low-power radiator. Detection of ionospheric perturbations of this kind by radiophysical complexes based on the decameter radiotelescope URAN-3 is discussed.

  14. Sequential Model-Based Detection in a Shallow Ocean Acoustic Environment

    SciTech Connect

    Candy, J V

    2002-03-26

    A model-based detection scheme is developed to passively monitor an ocean acoustic environment along with its associated variations. The technique employs an embedded model-based processor and a reference model in a sequential likelihood detection scheme. The monitor is therefore called a sequential reference detector. The underlying theory for the design is developed and discussed in detail.

  15. Depression Diagnoses and Fundamental Frequency-Based Acoustic Cues in Maternal Infant-Directed Speech

    ERIC Educational Resources Information Center

    Porritt, Laura L.; Zinser, Michael C.; Bachorowski, Jo-Anne; Kaplan, Peter S.

    2014-01-01

    F[subscript 0]-based acoustic measures were extracted from a brief, sentence-final target word spoken during structured play interactions between mothers and their 3- to 14-month-old infants and were analyzed based on demographic variables and DSM-IV Axis-I clinical diagnoses and their common modifiers. F[subscript 0] range (?F[subscript 0]) was…

  16. Direct to Digital Holography

    SciTech Connect

    Bingham, P.R.; Tobin, K.W.

    2007-09-30

    In this Cooperative Research and Development Agreement (CRADA), Oak Ridge National Laboratory (ORNL) assisted nLine Corporation of Austin, TX in the development of prototype semiconductor wafer inspection tools based on the direct-to-digital holographic (DDH) techniques invented at ORNL. Key components of this work included, testing of DDH for detection of defects in High Aspect Ratio (HAR) structures, development of image processing techniques to enhance detection capabilities through the use of both phase and intensity, and development of methods for autofocus on the DDH tools.

  17. Direct to Digital Holography

    SciTech Connect

    Bingham, P.R.; Tobin, K.W.

    2002-06-15

    In this CRADA, Oak Ridge National Laboratory (ORNL) assisted nLine Corporation of Austin, TX in the development of prototype semiconductor wafer inspection tools based on the direct-to-digital holographic (DDH) techniques invented at ORNL. Key components of this work included, testing of DDH for detection of defects in High Aspect Ratio (HAR) structures, development of image processing techniques to enhance detection capabilities through the use of both phase and intensity, and development of methods for autofocus on the DDH tools.

  18. Visualizing Breath using Digital Holography

    NASA Astrophysics Data System (ADS)

    Hobson, P. R.; Reid, I. D.; Wilton, J. B.

    2013-02-01

    Artist Jayne Wilton and physicists Peter Hobson and Ivan Reid of Brunel University are collaborating at Brunel University on a project which aims to use a range of techniques to make visible the normally invisible dynamics of the breath and the verbal and non-verbal communication it facilitates. The breath is a source of a wide range of chemical, auditory and physical exchanges with the direct environment. Digital Holography is being investigated to enable a visually stimulating articulation of the physical trajectory of the breath as it leaves the mouth. Initial findings of this research are presented. Real time digital hologram replay allows the audience to move through holographs of breath-born particles.

  19. Object detection and tracking method of AUV based on acoustic vision

    NASA Astrophysics Data System (ADS)

    Zhang, Tie-dong; Wan, Lei; Zeng, Wen-jing; Xu, Yu-ru

    2012-12-01

    This paper describes a new framework for object detection and tracking of AUV including underwater acoustic data interpolation, underwater acoustic images segmentation and underwater objects tracking. This framework is applied to the design of vision-based method for AUV based on the forward looking sonar sensor. First, the real-time data flow (underwater acoustic images) is pre-processed to form the whole underwater acoustic image, and the relevant position information of objects is extracted and determined. An improved method of double threshold segmentation is proposed to resolve the problem that the threshold cannot be adjusted adaptively in the traditional method. Second, a representation of region information is created in light of the Gaussian particle filter. The weighted integration strategy combining the area and invariant moment is proposed to perfect the weight of particles and to enhance the tracking robustness. Results obtained on the real acoustic vision platform of AUV during sea trials are displayed and discussed. They show that the proposed method can detect and track the moving objects underwater online, and it is effective and robust.

  20. Waveform Based Acoustic Emission Detection and Location of Matrix Cracking in Composites

    NASA Technical Reports Server (NTRS)

    Prosser, W. H.

    1995-01-01

    The operation of damage mechanisms in a material or structure under load produces transient acoustic waves. These acoustic waves are known as acoustic emission (AE). In composites they can be caused by a variety of sources including matrix cracking, fiber breakage, and delamination. AE signals can be detected and analyzed to determine the location of the acoustic source by triangulation. Attempts are also made to analyze the signals to determine the type and severity of the damage mechanism. AE monitoring has been widely used for both laboratory studies of materials, and for testing the integrity of structures in the field. In this work, an advanced, waveform based AE system was used in a study of transverse matrix cracking in cross-ply graphite/epoxy laminates. This AE system featured broad band, high fidelity sensors, and high capture rate digital acquisition and storage of acoustic signals. In addition, analysis techniques based on plate wave propagation models were employed. These features provided superior source location and noise rejection capabilities.

  1. Modeling and optimization of an acoustic diode based on micro-bubble nonlinearity.

    PubMed

    Guo, Xiasheng; Lin, Zhou; Tu, Juan; Liang, Bin; Cheng, Jianchun; Zhang, Dong

    2013-02-01

    The first acoustic diode (AD), which is composed by integrating a super lattice (SL) with a nonlinear medium (NLM), has recently been proposed to make a one-way street for the acoustic energy flux. This device prohibits the acoustic waves from one direction, but allows the transmission of the second harmonic wave (generated from the NLM) from the other direction. To improve its performance, it is crucial to transfer more acoustic energy from the stop-band of the acoustic filter (i.e., the SL) to its pass-band with the help of the NLM. In this work, a finite difference time domain model is developed to study the dynamic behaviors of the AD, in which a micro-bubble suspension takes the role of the NLM. Based on this model, the method of optimizing the nonlinearity-based AD is investigated by examining its performance with respect to several parameters, such as the periodicity number of the SL, the bubble size distribution, the bubble shell parameters, and the bubble concentration. It is also suggested that, instead of the rectification ratio, it might be more reasonable to characterize the performance of the AD with the energy attenuation coefficients (or transmission loss) for both incident directions.

  2. Digital holography to light field

    NASA Astrophysics Data System (ADS)

    Asundi, Anand; Zuo, Chao

    2014-05-01

    Holography uses wave (physical) optical principles of interference and diffraction to record and display images. Interference allows us to record the amplitude and phase of the optical wave emanating from an object on a film or recording medium and diffraction enables us to see this wave-field, i.e. the amplitude and phase of the object. Visually this corresponds to both perspective and depth information being reconstructed as in the original scene. Digital Holography has enabled quantification of phase which in some applications provides meaningful engineering parameters. There is growing interest in reconstructing this wavefield without interference. Thus the non-interferometric Transport of Intensity Equation (TIE) method is gaining increased research, which uses two or more defocused images to reconstruct the phase. Due to its non-interferometric nature, TIE relaxes the stringent beam-coherence requirements for interferometry, extending its applications to various optical fields with arbitrary spatial and temporal coherence. The alternate school of thought emerges from the computer science community primarily deals with ray optics. In a normal imaging system all rays emerging from an object point into are focused to a conjugate image point. Information of ray direction is lost and thus the perspective and depth information. A light field image is one that has information of both amplitude and direction of rays fanning from any object point and thus provides perspective (or what could be termed as phase) of the object wave as well. It would thus be possible to extract phase as we know it from this albeit for a coherent illumination case.

  3. Ground-based acoustic parametric generator impact on the atmosphere and ionosphere in an active experiment

    NASA Astrophysics Data System (ADS)

    Rapoport, Yuriy G.; Cheremnykh, Oleg K.; Koshovy, Volodymyr V.; Melnik, Mykola O.; Ivantyshyn, Oleh L.; Nogach, Roman T.; Selivanov, Yuriy A.; Grimalsky, Vladimir V.; Mezentsev, Valentyn P.; Karataeva, Larysa M.; Ivchenko, Vasyl. M.; Milinevsky, Gennadi P.; Fedun, Viktor N.; Tkachenko, Eugen N.

    2017-01-01

    We develop theoretical basics of active experiments with two beams of acoustic waves, radiated by a ground-based sound generator. These beams are transformed into atmospheric acoustic gravity waves (AGWs), which have parameters that enable them to penetrate to the altitudes of the ionospheric E and F regions where they influence the electron concentration of the ionosphere. Acoustic waves are generated by the ground-based parametric sound generator (PSG) at the two close frequencies. The main idea of the experiment is to design the output parameters of the PSG to build a cascade scheme of nonlinear wave frequency downshift transformations to provide the necessary conditions for their vertical propagation and to enable penetration to ionospheric altitudes. The PSG generates sound waves (SWs) with frequencies f1 = 600 and f2 = 625 Hz and large amplitudes (100-420 m s-1). Each of these waves is modulated with the frequency of 0.016 Hz. The novelty of the proposed analytical-numerical model is due to simultaneous accounting for nonlinearity, diffraction, losses, and dispersion and inclusion of the two-stage transformation (1) of the initial acoustic waves to the acoustic wave with the difference frequency Δf = f2 - f1 in the altitude ranges 0-0.1 km, in the strongly nonlinear regime, and (2) of the acoustic wave with the difference frequency to atmospheric acoustic gravity waves with the modulational frequency in the altitude ranges 0.1-20 km, which then reach the altitudes of the ionospheric E and F regions, in a practically linear regime. AGWs, nonlinearly transformed from the sound waves, launched by the two-frequency ground-based sound generator can increase the transparency of the ionosphere for the electromagnetic waves in HF (MHz) and VLF (kHz) ranges. The developed theoretical model can be used for interpreting an active experiment that includes the PSG impact on the atmosphere-ionosphere system, measurements of electromagnetic and acoustic fields, study of

  4. Frustrated total internal reflection acoustic field sensor

    DOEpatents

    Kallman, Jeffrey S.

    2000-01-01

    A frustrated total internal reflection acoustic field sensor which allows the acquisition of the acoustic field over an entire plane, all at once. The sensor finds use in acoustic holography and acoustic diffraction tomography. For example, the sensor may be produced by a transparent plate with transparent support members tall enough to support one or more flexible membranes at an appropriate height for frustrated total internal reflection to occur. An acoustic wave causes the membrane to deflect away from its quiescent position and thus changes the amount of light that tunnels through the gap formed by the support members and into the membrane, and so changes the amount of light reflected by the membrane. The sensor(s) is illuminated by a uniform tight field, and the reflection from the sensor yields acoustic wave amplitude and phase information which can be picked up electronically or otherwise.

  5. A Screening Approach for Classroom Acoustics Using Web-Based Listening Tests and Subjective Ratings

    PubMed Central

    Persson Waye, Kerstin; Magnusson, Lennart; Fredriksson, Sofie; Croy, Ilona

    2015-01-01

    Background Perception of speech is crucial in school where speech is the main mode of communication. The aim of the study was to evaluate whether a web based approach including listening tests and questionnaires could be used as a screening tool for poor classroom acoustics. The prime focus was the relation between pupils’ comprehension of speech, the classroom acoustics and their description of the acoustic qualities of the classroom. Methodology/Principal Findings In total, 1106 pupils aged 13-19, from 59 classes and 38 schools in Sweden participated in a listening study using Hagerman’s sentences administered via Internet. Four listening conditions were applied: high and low background noise level and positions close and far away from the loudspeaker. The pupils described the acoustic quality of the classroom and teachers provided information on the physical features of the classroom using questionnaires. Conclusions/Significance In 69% of the classes, at least three pupils described the sound environment as adverse and in 88% of the classes one or more pupil reported often having difficulties concentrating due to noise. The pupils’ comprehension of speech was strongly influenced by the background noise level (p<0.001) and distance to the loudspeakers (p<0.001). Of the physical classroom features, presence of suspended acoustic panels (p<0.05) and length of the classroom (p<0.01) predicted speech comprehension. Of the pupils’ descriptions of acoustic qualities, clattery significantly (p<0.05) predicted speech comprehension. Clattery was furthermore associated to difficulties understanding each other, while the description noisy was associated to concentration difficulties. The majority of classrooms do not seem to have an optimal sound environment. The pupil’s descriptions of acoustic qualities and listening tests can be one way of predicting sound conditions in the classroom. PMID:25615692

  6. Listeners' expectation of room acoustical parameters based on visual cues

    NASA Astrophysics Data System (ADS)

    Valente, Daniel L.

    Despite many studies investigating auditory spatial impressions in rooms, few have addressed the impact of simultaneous visual cues on localization and the perception of spaciousness. The current research presents an immersive audio-visual study, in which participants are instructed to make spatial congruency and quantity judgments in dynamic cross-modal environments. The results of these psychophysical tests suggest the importance of consilient audio-visual presentation to the legibility of an auditory scene. Several studies have looked into audio-visual interaction in room perception in recent years, but these studies rely on static images, speech signals, or photographs alone to represent the visual scene. Building on these studies, the aim is to propose a testing method that uses monochromatic compositing (blue-screen technique) to position a studio recording of a musical performance in a number of virtual acoustical environments and ask subjects to assess these environments. In the first experiment of the study, video footage was taken from five rooms varying in physical size from a small studio to a small performance hall. Participants were asked to perceptually align two distinct acoustical parameters---early-to-late reverberant energy ratio and reverberation time---of two solo musical performances in five contrasting visual environments according to their expectations of how the room should sound given its visual appearance. In the second experiment in the study, video footage shot from four different listening positions within a general-purpose space was coupled with sounds derived from measured binaural impulse responses (IRs). The relationship between the presented image, sound, and virtual receiver position was examined. It was found that many visual cues caused different perceived events of the acoustic environment. This included the visual attributes of the space in which the performance was located as well as the visual attributes of the performer

  7. A novel thermal acoustic device based on porous graphene

    NASA Astrophysics Data System (ADS)

    Tao, Lu-Qi; Liu, Ying; Tian, He; Ju, Zhen-Yi; Xie, Qian-Yi; Yang, Yi; Ren, Tian-Ling

    2016-01-01

    A thermal acoustic (TA) device was fabricated by laser scribing technology. Polyimide (PI) can be converted into patterned porous graphene (PG) by laser's irradiation in one step. The sound pressure level (SPL) of such TA device is related to laser power. The theoretical model of TA effect was established to analyze the relationship between the SPL and laser power. The theoretical results are in good agreement with experiment results. It was found that PG has a flat frequency response in the range of 5-20 kHz. This novel TA device has the advantages of one-step procedure, high flexibility, no mechanical vibration, low cost and so on. It can open wide applications in speakers, multimedia, medical, earphones, consumer electronics and many other aspects.

  8. Cyclodextrin-based surface acoustic wave chemical microsensors

    SciTech Connect

    Li, D.Q.; Shi, J.X.; Springer, K.; Swanson, B.I.

    1996-07-01

    Cyclodextrin thin films were fabricated using either self-assembled monolayer (SAM) or solgel techniques. The resulting host receptor thin films on the substrates of surface acoustic wave (SAW) resonators were studied as method of tracking organic toxins in vapor phase. The mass loading of surface-attached host monolayers on SAW resonators gave frequency shifts corresponding to typical monolayer surface coverages for SAM methods and ``multilayer`` coverages for sol-gel techniques. Subsequent exposure of the coated SAW resonators to organic vapors at various concentrations, typically 5,000 parts per millions (ppm) down to 100 parts per billions (ppb) by mole, gave responses indicating middle-ppb-sensitivity ({approximately}50 ppb) for those sensor-host-receptors and organic-toxin pairs with optimum mutual matching of polarity, size, and structural properties.

  9. Trailing Edge Noise Prediction Based on a New Acoustic Formulation

    NASA Technical Reports Server (NTRS)

    Casper, J.; Farassat, F.

    2002-01-01

    A new analytic result in acoustics called 'Formulation 1B,' proposed by Farassat, is used to compute broadband trailing edge noise from an unsteady surface pressure distribution on a thin airfoil in the time domain. This formulation is a new solution of the Ffowcs Williams-Hawkings equation with the loading source term, and has been shown in previous research to provide time domain predictions of broadband noise that are in excellent agreement with experiment. Furthermore, this formulation lends itself readily to rotating reference frames and statistical analysis of broadband trailing edge noise. Formulation 1B is used to calculate the far field noise radiated from the trailing edge of a NACA 0012 airfoil in low Mach number flows, using both analytical and experimental data on the airfoil surface. The results are compared to analytical results and experimental measurements that are available in the literature. Good agreement between predictions and measurements is obtained.

  10. A new capnograph based on an electro acoustic sensor.

    PubMed

    Folke, M; Hök, B

    2008-01-01

    End tidal carbon dioxide measurements with an electro acoustic capnograph prototype have been demonstrated. The aim of this study was to verify that it is possible to obtain an adequate capnogram using the prototype and to investigate the influence of ambient temperature and humidity variations. By simultaneous measurements with a reference capnograph, on subjects performing exercise, hypo- and hyperventilation, P(ET)CO(2) readings from the reference were compared with the output signal from the prototype. The capnogram from the prototype correlated well with the reference in terms of breath time. The first parts of the expiration and inspiration phases were steeper for the reference than the prototype. The output signal from the prototype correlated well with the reference P(ET)CO(2) readings with a correlation coefficient of 0.93 at varied temperature and relative humidity.

  11. A novel thermal acoustic device based on porous graphene

    SciTech Connect

    Tao, Lu-Qi; Liu, Ying; Ju, Zhen-Yi; Xie, Qian-Yi; Yang, Yi; Ren, Tian-Ling; Tian, He

    2016-01-15

    A thermal acoustic (TA) device was fabricated by laser scribing technology. Polyimide (PI) can be converted into patterned porous graphene (PG) by laser’s irradiation in one step. The sound pressure level (SPL) of such TA device is related to laser power. The theoretical model of TA effect was established to analyze the relationship between the SPL and laser power. The theoretical results are in good agreement with experiment results. It was found that PG has a flat frequency response in the range of 5-20 kHz. This novel TA device has the advantages of one-step procedure, high flexibility, no mechanical vibration, low cost and so on. It can open wide applications in speakers, multimedia, medical, earphones, consumer electronics and many other aspects.

  12. The Biological Sensor for Detection of Bacterial Cells in Liquid Phase Based on Plate Acoustic Wave

    NASA Astrophysics Data System (ADS)

    Borodina, Irina; Zaitsev, Boris; Shikhabudinov, Alexander; Guliy, Olga; Ignatov, Oleg; Teplykh, Andrey

    The interactions "bacterial cells - bacteriophages", "bacterial cells - antibodies" and "bacterial cells - mini- antibodies" directly in liquid phase were experimentally investigated with a help of acoustic sensor. The acoustic sensor under study represents two-channel delay line based on the plate of Y-X lithium niobate. One channel of delay line was electrically shorted, the second channel was electrically open. The liquid container was glued on plate surface between transducers of delay line. The dependencies of the change in phase and insertion loss on concentration of bacteriophages, antibodies, and mini- antibodies were obtained for both channels of delay line.

  13. Distributed acoustic mapping based on interferometry of phase optical time-domain reflectometry

    NASA Astrophysics Data System (ADS)

    Wang, Chang; Wang, Chen; Shang, Ying; Liu, Xiaohui; Peng, Gangding

    2015-07-01

    We demonstrate the design and characterization of a distributed optical fiber sensing system based on Michelson interferometer of the phase sensitive optical time domain reflectometer (φ-OTDR) for acoustic measurement. Phase, amplitude, frequency response and location information can be directly obtained at the same time by using the passive 3×3 coupler demodulation. In order to simulate sound profiles of seismic or hydroacoustic imaging, experiments on detection of multiple piezoelectric transducers (PZT) are carried out. The result shows that our system can well demodulate different acoustic sources with different intensities.

  14. Differentiation of red wines using an electronic nose based on surface acoustic wave devices.

    PubMed

    García, M; Fernández, M J; Fontecha, J L; Lozano, J; Santos, J P; Aleixandre, M; Sayago, I; Gutiérrez, J; Horrillo, M C

    2006-02-15

    An electronic nose, utilizing the principle of surface acoustic waves (SAW), was used to differentiate among different wines of the same variety of grapes which come from the same cellar. The electronic nose is based on eight surface acoustic wave sensors, one is a reference sensor and the others are coated by different polymers by spray coating technique. Data analysis was performed by two pattern recognition methods; principal component analysis (PCA) and probabilistic neuronal network (PNN). The results showed that electronic nose was able to identify the tested wines.

  15. Diaphragm based long cavity Fabry-Perot fiber acoustic sensor using phase generated carrier

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Lin, Jie; Liu, Huan; Ma, Yuan; Yan, Lei; Jin, Peng

    2017-01-01

    A diaphragm based long cavity Fabry-Perot interferometric fiber acoustic sensor is proposed. The Fabry-Perot cavity is formed by a flat fiber facet and an ultra-thin silver diaphragm with a 6-meter long fiber inserted in the cavity. A narrow-linewidth ring-cavity erbium-doped fiber laser is applied to demodulate the sensing signal in the phase generated carrier algorithm. Experimental results have demonstrated that the phase sensitivity is about -140 dB re 1 rad/μPa at 2 kHz. The noise equivalent acoustic signal level is 60.6 μPa/Hz1/2 and the dynamic range is 65.1 dB-SPL at 2 kHz. The sensor is suitable for sensing of weak acoustic signals.

  16. Quasi-distributed acoustic sensing based on identical low-reflective fiber Bragg gratings

    NASA Astrophysics Data System (ADS)

    Shang, Ying; Yang, Yuan-Hong; Wang, Chen; Liu, Xiao-Hui; Wang, Chang; Peng, Gang-Ding

    2017-01-01

    A quasi-distributed acoustic sensing (QDAS) scheme based on identical low-reflective fiber Bragg grating is proposed and analyzed theoretically and experimentally. We realize the acoustic demodulation of different location and different frequency simultaneously by using imbalanced Michelson interferometer of φ-OTDR and Phase Generated Carrier technology with 600 identical low-reflective fiber Bragg gratings(FBGs) written on-line during drawing of the ordinary signal mode fibers in an equal separation of 2 m. We further obtain the 1.4 dB of frequency response flatness at the range of 200 Hz-1500 Hz and proportional character of demodulated intensity of acoustic sources with different drive voltage of underwater speaker in the experiment.

  17. Guiding and confinement of interface acoustic waves in solid-fluid pillar-based phononic crystals

    NASA Astrophysics Data System (ADS)

    Razip Wee, M. F. Mohd; Addouche, Mahmoud; Siow, Kim S.; Zain, A. R. Md; Elayouch, Aliyasin; Chollet, Franck; Khelif, Abdelkrim

    2016-12-01

    Pillar-based phononic crystals exhibit some unique wave phenomena due to the interaction between surface acoustic modes of the substrate and local resonances supported by pillars. In this paper, we extend the investigations by taking into account the presence of a liquid medium. We particularly demonstrate that local resonances dramatically decrease the phase velocity of Scholte-Stoneley wave, which leads to a slow wave at the solid/fluid interface. Moreover, we show that increasing the height of pillars introduces a new set of branches of interface modes and drastically affects the acoustic energy localization. Indeed, while some modes display a highly confined pressure between pillars, others exponentially decay in the fluid or only propagate in the solid without disturbing the fluid pressure. These theoretical results, performed by finite element method, highlight a new acoustic wave confinement suitable in various applications such as acoustophoresis, lab on chip and microfluidics.

  18. An acoustic-convective splitting-based approach for the Kapila two-phase flow model

    NASA Astrophysics Data System (ADS)

    ten Eikelder, M. F. P.; Daude, F.; Koren, B.; Tijsseling, A. S.

    2017-02-01

    In this paper we propose a new acoustic-convective splitting-based numerical scheme for the Kapila five-equation two-phase flow model. The splitting operator decouples the acoustic waves and convective waves. The resulting two submodels are alternately numerically solved to approximate the solution of the entire model. The Lagrangian form of the acoustic submodel is numerically solved using an HLLC-type Riemann solver whereas the convective part is approximated with an upwind scheme. The result is a simple method which allows for a general equation of state. Numerical computations are performed for standard two-phase shock tube problems. A comparison is made with a non-splitting approach. The results are in good agreement with reference results and exact solutions.

  19. A cantilever based optical fiber acoustic sensor fabricated by femtosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Yuan, Lei; Huang, Jie; Xiao, Hai

    2016-04-01

    In this paper, we present a pure silica micro-cantilever based optical fiber sensor for acoustic wave detection. The cantilever is directly fabricated by fs laser micromachining on an optical fiber tip functioning as an inline Fabry-Perot interferometer (FPI). The applied acoustic wave pressurizes the micro-cantilever beam and the corresponding dynamic signals can be probed by the FPI. The thickness, length, and width of the micro-cantilever beam can be flexibly designed and fabricated so that the sensitivity, frequency response, and the total measurement range can be varied to fit many practical applications. Experimental results will be presented and analyzed. Due to the assembly free fabrication of the fs-laser, multiple micro-cantilever beams could be potentially fabricated in/on a single optical fiber for quasi-distributed acoustic mapping with high spatial resolution.

  20. Experimental study on acoustic subwavelength imaging based on zero-mass metamaterials

    NASA Astrophysics Data System (ADS)

    Xu, Xianchen; Li, Pei; Zhou, Xiaoming; Hu, Gengkai

    2015-01-01

    Anisotropic zero-mass acoustic metamaterials are able to transmit evanescent waves without decaying to a far distance, and have been used for near-field acoustic subwavelength imaging. In this work, we design and fabricate such metamaterial lens based on clamped paper membrane units. The zero-mass frequency is determined by normal-incidence acoustic transmission measurement. At this frequency, we verify in experiment that the fabricated metamaterial lens is able to distinguish clearly two sound sources separated with a distance 0.16λ0 (λ0 is the wavelength in air) below the diffraction limit. We also demonstrate that the imaging frequency is invariant to the change of the lens thickness.

  1. Ray-trace modeling of acoustic Green's function based on the semiclassical (eikonal) approximation.

    PubMed

    Prislan, Rok; Veble, Gregor; Svenšek, Daniel

    2016-10-01

    The Green's function (GF) for the scalar wave equation is numerically constructed by an advanced geometric ray-tracing method based on the eikonal approximation related to the semiclassical propagator. The underlying theory is first briefly introduced, and then it is applied to acoustics and implemented in a ray-tracing-type numerical simulation. The so constructed numerical method is systematically used to calculate the sound field in a rectangular (cuboid) room, yielding also the acoustic modes of the room. The simulated GF is rigorously compared to its analytic approximation. Good agreement is found, which proves the devised numerical approach potentially useful also for low frequency acoustic modeling, which is in practice not covered by geometrical methods.

  2. Diagnosing the Bottom of the Vertical Tank, a Device Based on the Phased Acoustic Gratings

    NASA Astrophysics Data System (ADS)

    Bezborodov, Yu; Selsky, A.; Lysyannikova, N.; Kravtsova, Ye; Lysyannikov, A.; Shram, V.; Kaiser, Yu; Merko, M.

    2016-06-01

    This paper presents a decision on the creation of a specialized low-frequency flaw detector operating on acoustic phased arrays. A defectoscope will solve the problem of oil leakage through diagnostics of installation or operational defects of the bottom base metal sheets that are difficult to detect by conventional methods of testing due to a large area of the object.

  3. An evaluation study of mycelium based acoustic absorbers grown on agricultural by-product substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research examines the use of a novel new renewable resource in acoustic absorption applications. The material under test is based on the fruiting body of fungi, a mushroom, in the phylum of Basidiomycetes, which are grown on semi-hydrophobic substrates such as cotton by-products, leaves, sticks...

  4. Evaluation of Mycelium Based Acoustic Absorbers Grown on Select Agricultural Byproduct Substrates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research examines the use of a novel new renewable resource in acoustic absorption applications. The material under test is based on the fruiting body of fungi, a mushroom, in the phylum of Basidiomycetes, which are grown on semi-hydrophobic substrates such as cotton byproducts, leaves, sticks ...

  5. Search-matching algorithm for acoustics-based automatic sniper localization

    NASA Astrophysics Data System (ADS)

    Aguilar, Juan R.; Salinas, Renato A.; Abidi, Mongi A.

    2007-04-01

    Most of modern automatic sniper localization systems are based on the utilization of the acoustical emissions produced by the gun fire events. In order to estimate the spatial coordinates of the sniper location, these systems measures the time delay of arrival of the acoustical shock wave fronts to a microphone array. In more advanced systems, model based estimation of the nonlinear distortion parameters of the N-waves is used to make projectile trajectory and calibre estimations. In this work we address the sniper localization problem using a model based search-matching approach. The automatic sniper localization algorithm works searching for the acoustics model of ballistic shock waves which best matches the measured data. For this purpose, we implement a previously released acoustics model of ballistic shock waves. Further, the sniper location, the projectile trajectory and calibre, and the muzzle velocity are regarded as the inputs variables of such a model. A search algorithm is implemented in order to found what combination of the input variables minimize a fitness function defined as the distance between measured and simulated data. In such a way, the sniper location, the projectile trajectory and calibre, and the muzzle velocity can be found. In order to evaluate the performance of the algorithm, we conduct computer based experiments using simulated gunfire event data calculated at the nodes of a virtual distributed sensor network. Preliminary simulation results are quite promising showing fast convergence of the algorithm and good localization accuracy.

  6. Applications of Digital Holography: From Microscopy to 3D-Television

    NASA Astrophysics Data System (ADS)

    Kreis, T.

    2012-03-01

    The paper gives an overview of the applications of digital holography based on the one hand on CCD-recording, computer storage, and numerical reconstruction of the wave fields, and on the other hand on numerical calculation of computer generated holograms (CGH) and the transfer of these CGHs to spatial light modulators (SLM) for optical reconstruction of the wave fields. The first mentioned type of digital holography finds applications in digital holographic microscopy, particle analysis, and interferometric form and deformation measurement, while the second type constitutes the basis for holographic 3D TV. The space-bandwidth-problem occuring in this context is addressed and first partial solutions are presented.

  7. Recent developments on holography in China

    NASA Astrophysics Data System (ADS)

    Hsu, Dahsiung; Jiao, Jiangzhong; Tao, Huiying; Long, Pin

    1991-02-01

    Since the 1985 Lake Forest International Conference on display holography, USA) more developments have been made on holographic applications in China among which the important events and progress were: the International Conference on holography applications em bossing holography new holographic optical elements and equipments etc. . 1. INTERNATIONAL CONFEPENCE ON GRAPHY APPLICATIONS'' ( I CHA ''86. BEIJING) More than 280 holographers from 18 countries gathered in the Science Hall in Beijing from July 2 to for the International Conference on holography applications''86. The conference was sponsor ed by the Chinese OPtical Society the Chinese Theoretical Applied Mechanics Society and cosponsored by the Society of Photooptical Instrumentation Engineers the European Photonic Association in cooperation with the China Association for Science And Technology. It was chaired by Prof. Wang Daheng vice president of the China Association for Science Technology and president of the Chinese Optical Society cochaired by DP. H. J. Caulfield of the Univ. of Alabama Dr. G. von Bally of the Munster Univ. in West Germany and Dr. J. Tsujiuchi of the Tokyo Institute of Technology. SPIE Vol. 1238 Three-Dimensional Holography: Science Culture Education (1989) / 13

  8. [Research on Time-frequency Characteristics of Magneto-acoustic Signal of Different Thickness Medium Based on Wave Summing Method].

    PubMed

    Zhang, Shunqi; Yin, Tao; Ma, Ren; Liu, Zhipeng

    2015-08-01

    Functional imaging method of biological electrical characteristics based on magneto-acoustic effect gives valuable information of tissue in early tumor diagnosis, therein time and frequency characteristics analysis of magneto-acoustic signal is important in image reconstruction. This paper proposes wave summing method based on Green function solution for acoustic source of magneto-acoustic effect. Simulations and analysis under quasi 1D transmission condition are carried out to time and frequency characteristics of magneto-acoustic signal of models with different thickness. Simulation results of magneto-acoustic signal were verified through experiments. Results of the simulation with different thickness showed that time-frequency characteristics of magneto-acoustic signal reflected thickness of sample. Thin sample, which is less than one wavelength of pulse, and thick sample, which is larger than one wavelength, showed different summed waveform and frequency characteristics, due to difference of summing thickness. Experimental results verified theoretical analysis and simulation results. This research has laid a foundation for acoustic source and conductivity reconstruction to the medium with different thickness in magneto-acoustic imaging.

  9. Wavelet image processing applied to optical and digital holography: past achievements and future challenges

    NASA Astrophysics Data System (ADS)

    Jones, Katharine J.

    2005-08-01

    The link between wavelets and optics goes back to the work of Dennis Gabor who both invented holography and developed Gabor decompositions. Holography involves 3-D images. Gabor decompositions involves 1-D signals. Gabor decompositions are the predecessors of wavelets. Wavelet image processing of holography, both optical holography and digital holography, will be examined with respect to past achievements and future challenges.

  10. Improved phonocardiogram system based on acoustic impedance matching.

    PubMed

    Schwartz, R S; Reeves, J T; Sodal, I E; Barnes, F S

    1980-04-01

    We considered that phonocardiographic recording could be improved 1) by minimizing the acoustic impedance mismatch between the precordial tissue and transducer, 2) by optimizing the configuration of the impedance-matching medium and transducer design, and 3) by storing signals in digital form through analog-to-digital conversion of analog recordings made at the bedside. The use of an aqueous coupling medium to improve energy transmission increased signal voltage approximately 100-fold over presently used commercial devices. Further match to the crystal was achieved by a concentrating horn configuration for the aqueous medium. Measured frequency response of the device in the range 1 Hz to 1 kHz was better than two other commercially tested microphones. Inspection of comparative phonocardiograms showed more information from the new device than from the two other commercial devices. Unfiltered digitized signals, using our microphone in normal subjects, demonstrated good beat-to-beat repeatability, but analog filtering to obtain the conventional phonocardiogram showed significant loss of information. The new instrument appears to be superior to those commercial devices tested in recording heart sounds.

  11. Pressure transducer for measuring acoustic radiation force based on a magnetic sensor

    NASA Astrophysics Data System (ADS)

    Kamimura, H. A. S.; Pavan, T. Z.; Almeida, T. W. J.; Pádua, M. L. A.; Baggio, A. L.; Fatemi, M.; Carneiro, A. A. O.

    2011-01-01

    This work presents a pressure transducer based on a magnetic sensor to measure acoustic radiation force (ARF) and small displacements. The methodology presented in this paper allowed this transducer to be calibrated for use as an acoustic pressure and intensity meter. It can control the acoustic intensity emitted by ultrasound used, for example, in ARF impulse imaging, vibro-acoustography and high-intensity focused ultrasound techniques. The device comprises a magnet, a membrane, a magnetoresistive sensor and a coil to cancel the external magnetic field. When ARF is applied to the membrane, the magnetic field on the sensor changes due to the magnetic target displacement. The variation of the output signal from the magnetic transducer is proportional to the acoustic pressure applied to the membrane. A focused ultrasound transducer with a central frequency of 3 MHz was used to apply a continuous ARF. The sensitivities of the magnetic transducer as an acoustic pressure and intensity meter, evaluated in water, were respectively 0.597 µV MPa-1 and 0.073 µV (W cm-2)-1/2, while those of the needle hydrophone (Onda model HNP-0400) used in the magnetic transducer calibration were respectively, 0.5024 mV MPa-1 and 6.153 mV (W cm-2)-1/2. The transducer resolution to displacement is 5 nm and 6 dB of signal attenuation occurs for 7° of misalignment. The transducer responded well to acoustic pressure in water above 200 kPa.

  12. m-Learning and holography: Compatible techniques?

    NASA Astrophysics Data System (ADS)

    Calvo, Maria L.

    2014-07-01

    Since the last decades, cell phones have become increasingly popular and are nowadays ubiquitous. New generations of cell phones are now equipped with text messaging, internet, and camera features. They are now making their way into the classroom. This is creating a new teaching and learning technique, the so called m-Learning (or mobile-Learning). Because of the many benefits that cell phones offer, teachers could easily use them as a teaching and learning tool. However, an additional work from the teachers for introducing their students into the m-Learning in the classroom needs to be defined and developed. As an example, optical techniques, based upon interference and diffraction phenomena, such as holography, appear to be convenient topics for m-Learning. They can be approached with simple examples and experiments within the cell phones performances and classroom accessibility. We will present some results carried out at the Faculty of Physical Sciences in UCM to obtain very simple holographic recordings via cell phones. The activities were carried out inside the course on Optical Coherence and Laser, offered to students in the fourth course of the Grade in Physical Sciences. Some open conclusions and proposals will be presented.

  13. Effective actions for relativistic fluids from holography

    NASA Astrophysics Data System (ADS)

    de Boer, Jan; Heller, Michal P.; Pinzani-Fokeeva, Natalia

    2015-08-01

    Motivated by recent progress in developing action formulations of relativistic hydrodynamics, we use holography to derive the low energy dissipationless effective action for strongly coupled conformal fluids. Our analysis is based on the study of novel double Dirichlet problems for the gravitational field, in which the boundary conditions are set on two codimension one timelike hypersurfaces (branes). We provide a geometric interpretation of the Goldstone bosons appearing in such constructions in terms of a family of spatial geodesics extending between the ultraviolet and the infrared brane. Furthermore, we discuss supplementing double Dirichlet problems with information about the near-horizon geometry. We show that upon coupling to a membrane paradigm boundary condition, our approach reproduces correctly the complex dispersion relation for both sound and shear waves. We also demonstrate that upon a Wick rotation, our formulation reproduces the equilibrium partition function formalism, provided the near- horizon geometry is properly accounted for. Finally, we define the conserved hydrodynamic entropy current as the Noether current associated with a particular transformation of the Goldstone bosons.

  14. Holography in the curriculum of medical institutes

    NASA Astrophysics Data System (ADS)

    Gorelik, S. Y.; Nagibina, I. M.; Baranov, S. V.; Bolshakov, Oleg P.; Petrishin, V. L.

    1995-11-01

    Holography at present is the most effective technique of obtaining 3-D images of different objects. That's why there is more and more dissemination of holography in different fields of science and engineering, for example, in medicine. So, last time the technique of synthesized holograms obtained for evaluating inner organs states of patients without surgical intervention was designed. Due to properties of the hologram such as high quality of image and relative simplicity of duplication it is clear that holography could take its place in the curriculum of medical specializations because posters, photos, and models cannot give a full notation about an object of interest. The attempt to obtain holographical complete sets to demonstrate the most frequent pathologic changes of a human's bones was undertaken by our Institutes. The aim of our research was to obtain holograms with the following properties: minimum cost and high quality of reconstructed image to identify both the presented objects and the pathologic changes of them.

  15. Advanced technology development multi-color holography

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.

    1994-01-01

    Several key aspects of multi-color holography and some non-conventional ways to study the holographic reconstructions are considered. The error analysis of three-color holography is considered in detail with particular example of a typical triglycine sulfate crystal growth situation. For the numerical analysis of the fringe patterns, a new algorithm is introduced with experimental verification using sugar-water solution. The role of the phase difference among component holograms is also critically considered with examples of several two- and three-color situations. The status of experimentation on two-color holography and fabrication of a small breadboard system is also reported. Finally, some successful demonstrations of unconventional ways to study holographic reconstructions are described. These methods are deflectometry and confocal optical processing using some Spacelab III holograms.

  16. Spin and wavelength multiplexed nonlinear metasurface holography

    PubMed Central

    Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

    2016-01-01

    Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam–Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption. PMID:27306147

  17. Optimization of input parameters of acoustic-transfection for the intracellular delivery of macromolecules using FRET-based biosensors

    NASA Astrophysics Data System (ADS)

    Yoon, Sangpil; Wang, Yingxiao; Shung, K. K.

    2016-03-01

    Acoustic-transfection technique has been developed for the first time. We have developed acoustic-transfection by integrating a high frequency ultrasonic transducer and a fluorescence microscope. High frequency ultrasound with the center frequency over 150 MHz can focus acoustic sound field into a confined area with the diameter of 10 μm or less. This focusing capability was used to perturb lipid bilayer of cell membrane to induce intracellular delivery of macromolecules. Single cell level imaging was performed to investigate the behavior of a targeted single-cell after acoustic-transfection. FRET-based Ca2+ biosensor was used to monitor intracellular concentration of Ca2+ after acoustic-transfection and the fluorescence intensity of propidium iodide (PI) was used to observe influx of PI molecules. We changed peak-to-peak voltages and pulse duration to optimize the input parameters of an acoustic pulse. Input parameters that can induce strong perturbations on cell membrane were found and size dependent intracellular delivery of macromolecules was explored. To increase the amount of delivered molecules by acoustic-transfection, we applied several acoustic pulses and the intensity of PI fluorescence increased step wise. Finally, optimized input parameters of acoustic-transfection system were used to deliver pMax-E2F1 plasmid and GFP expression 24 hours after the intracellular delivery was confirmed using HeLa cells.

  18. Probabilistic Neighborhood-Based Data Collection Algorithms for 3D Underwater Acoustic Sensor Networks

    PubMed Central

    Han, Guangjie; Li, Shanshan; Zhu, Chunsheng; Jiang, Jinfang; Zhang, Wenbo

    2017-01-01

    Marine environmental monitoring provides crucial information and support for the exploitation, utilization, and protection of marine resources. With the rapid development of information technology, the development of three-dimensional underwater acoustic sensor networks (3D UASNs) provides a novel strategy to acquire marine environment information conveniently, efficiently and accurately. However, the specific propagation effects of acoustic communication channel lead to decreased successful information delivery probability with increased distance. Therefore, we investigate two probabilistic neighborhood-based data collection algorithms for 3D UASNs which are based on a probabilistic acoustic communication model instead of the traditional deterministic acoustic communication model. An autonomous underwater vehicle (AUV) is employed to traverse along the designed path to collect data from neighborhoods. For 3D UASNs without prior deployment knowledge, partitioning the network into grids can allow the AUV to visit the central location of each grid for data collection. For 3D UASNs in which the deployment knowledge is known in advance, the AUV only needs to visit several selected locations by constructing a minimum probabilistic neighborhood covering set to reduce data latency. Otherwise, by increasing the transmission rounds, our proposed algorithms can provide a tradeoff between data collection latency and information gain. These algorithms are compared with basic Nearest-neighbor Heuristic algorithm via simulations. Simulation analyses show that our proposed algorithms can efficiently reduce the average data collection completion time, corresponding to a decrease of data latency. PMID:28208735

  19. Probabilistic Neighborhood-Based Data Collection Algorithms for 3D Underwater Acoustic Sensor Networks.

    PubMed

    Han, Guangjie; Li, Shanshan; Zhu, Chunsheng; Jiang, Jinfang; Zhang, Wenbo

    2017-02-08

    Marine environmental monitoring provides crucial information and support for the exploitation, utilization, and protection of marine resources. With the rapid development of information technology, the development of three-dimensional underwater acoustic sensor networks (3D UASNs) provides a novel strategy to acquire marine environment information conveniently, efficiently and accurately. However, the specific propagation effects of acoustic communication channel lead to decreased successful information delivery probability with increased distance. Therefore, we investigate two probabilistic neighborhood-based data collection algorithms for 3D UASNs which are based on a probabilistic acoustic communication model instead of the traditional deterministic acoustic communication model. An autonomous underwater vehicle (AUV) is employed to traverse along the designed path to collect data from neighborhoods. For 3D UASNs without prior deployment knowledge, partitioning the network into grids can allow the AUV to visit the central location of each grid for data collection. For 3D UASNs in which the deployment knowledge is known in advance, the AUV only needs to visit several selected locations by constructing a minimum probabilistic neighborhood covering set to reduce data latency. Otherwise, by increasing the transmission rounds, our proposed algorithms can provide a tradeoff between data collection latency and information gain. These algorithms are compared with basic Nearest-neighbor Heuristic algorithm via simulations. Simulation analyses show that our proposed algorithms can efficiently reduce the average data collection completion time, corresponding to a decrease of data latency.

  20. An Adaptive OFDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks

    PubMed Central

    Khalil, Issa M.; Gadallah, Yasser; Hayajneh, Mohammad; Khreishah, Abdallah

    2012-01-01

    Underwater acoustic wireless sensor networks (UAWSNs) have many applications across various civilian and military domains. However, they suffer from the limited available bandwidth of acoustic signals and harsh underwater conditions. In this work, we present an Orthogonal Frequency Division Multiple Access (OFDMA)-based Media Access Control (MAC) protocol that is configurable to suit the operating requirements of the underwater sensor network. The protocol has three modes of operation, namely random, equal opportunity and energy-conscious modes of operation. Our MAC design approach exploits the multi-path characteristics of a fading acoustic channel to convert it into parallel independent acoustic sub-channels that undergo flat fading. Communication between node pairs within the network is done using subsets of these sub-channels, depending on the configurations of the active mode of operation. Thus, the available limited bandwidth gets fully utilized while completely avoiding interference. We derive the mathematical model for optimal power loading and subcarrier selection, which is used as basis for all modes of operation of the protocol. We also conduct many simulation experiments to evaluate and compare our protocol with other Code Division Multiple Access (CDMA)-based MAC protocols. PMID:23012517

  1. Aircraft IR/acoustic detection evaluation. Volume 2: Development of a ground-based acoustic sensor system for the detection of subsonic jet-powered aircraft

    NASA Technical Reports Server (NTRS)

    Kraft, Robert E.

    1992-01-01

    The design and performance of a ground-based acoustic sensor system for the detection of subsonic jet-powered aircraft is described and specified. The acoustic detection system performance criteria will subsequently be used to determine target detection ranges for the subject contract. Although the defined system has never been built and demonstrated in the field, the design parameters were chosen on the basis of achievable technology and overall system practicality. Areas where additional information is needed to substantiate the design are identified.

  2. Dynamic modal characterization of musical instruments using digital holography.

    PubMed

    Demoli, Nazif; Demoli, Ivan

    2005-06-27

    This study shows that a dynamic modal characterization of musical instruments with membrane can be carried out using a low-cost device and that the obtained very informative results can be presented as a movie. The proposed device is based on a digital holography technique using the quasi-Fourier configuration and time-average principle. Its practical realization with a commercial digital camera and large plane mirrors allows relatively simple analyzing of big vibration surfaces. The experimental measurements given for a percussion instrument are supported by the mathematical formulation of the problem.

  3. Holography with a Landau pole

    NASA Astrophysics Data System (ADS)

    Faedo, Antón F.; Mateos, David; Pantelidou, Christiana; Tarrío, Javier

    2017-02-01

    Holography for UV-incomplete gauge theories is important but poorly understood. A paradigmatic example is d = 4, N=4 super Yang-Mills coupled to N f quark flavors, which possesses a Landau pole at a UV scale ΛLP. The dual gravity solution exhibits a UV singularity at a finite proper distance along the holographic direction. Despite this, holographic renormalization can be fully implemented via analytic continuation to an AdS solution. The presence of a UV cut-off manifests itself in several interesting ways. At energies E ≪ ΛLP no pathologies appear, as expected from effective field theory. In contrast, at scales E ≲ ΛLP the gravitational potential becomes repulsive, and at temperatures T ≲ ΛLP the specific heat becomes negative. Although we focus on N=4 super Yang-Mills with flavor, our qualitative results apply to a much more general class of theories, since they only depend on the fact that the metric near the UV singularity is a hyper-scaling violating metric with exponent θ > d - 1.

  4. DSS-24 microwave holography measurements

    NASA Technical Reports Server (NTRS)

    Rochblatt, D. J.; Withington, P. M.; Jackson, H. J.

    1995-01-01

    The JPL DSN Microwave Antenna Holography System (MAHST) was applied to the newly constructed DSS-24 34-m beam-waveguide antenna at Goldstone, California. The application of MAHST measurements and corrections at DSS 24 provided the critical RF performance necessary to not only meet the project requirements and goals, but to surpass them. A performance increase of 0.35 dB at X-band (8.45 GHz) and 4.9 dB at Ka-band (32 GHz) was provided by MAHST, resulting in peak efficiencies of 75.25 percent at X-band and 60.6 percent at Ka-band (measured from the Cassegrain focus at f1). The MAHST enabled setting the main reflector panels of DSS 24 to 0.25-mm rms, making DSS 24 the highest precision antenna in the NASA/JPL DSN. The precision of the DSS-24 antenna (diameter/rms) is 1.36 x 10(exp 5), and its gain limit is at 95 GHz.

  5. Acoustic perfect absorber based on metasurface with deep sub-wavelength thickness (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Assouar, Badreddine; Li, Yong

    2016-04-01

    The concept of the coiling up space, based on which artificial structures could exhibit extreme acoustic properties, such as high refractive index, double negativity, near-zero index, etc., have been investigated intensively recently due to the fascinating underlying physics and diverse potential applications [1-3]. One of the most important functionality is the ability to shrink bulky structures into deep sub-wavelength scale. It is therefore intuitive to prospect that the concept of coiling up space, if could be extended into the perforated system, will benefit to significantly reduce the total thickness while keeping total absorption. Conventional acoustic absorbers require a structure with a thickness comparable to the working wavelength, resulting major obstacles in real applications in low frequency range. We present a metasurface-based perfect absorber capable of achieving the total absorption of acoustic wave in extremely low frequency region. The metasurface possessing a deep sub-wavelength thickness down to a feature size of ~ lambda/223 is composed of a perforated plate and a coiled coplanar air chamber. Simulations based on fully coupled acoustic with thermodynamic equations and theoretical impedance analysis are utilized to reveal the underlying physics and the acoustic performances, showing an excellent agreement. Our realization should have high impact on amount of applications due to the extremely thin thickness, easy fabrication and high efficiency of the proposed structure. References 1. Z. Liang and J. Li, Phys. Rev. Lett. 108, 114301 (2012). 2. Y. Li, B. Liang, X. Tao, X. F. Zhu, X. Y. Zou, and J. C. Cheng, Appl. Phys. Lett. 101, 233508 (2012). 3. Y. Xie, W. Wang, H. Chen, A. Konneker, B. I. Popa, and S. A. Cummer, Nat. Commun. 5, 5553 (2014).

  6. Acoustic neuroma

    MedlinePlus

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

  7. Acoustic-wave sensor apparatus for analyzing a petroleum-based composition and sensing solidification of constituents therein

    DOEpatents

    Spates, J.J.; Martin, S.J.; Mansure, A.J.

    1997-08-26

    An acoustic-wave sensor apparatus and method are disclosed. The apparatus for analyzing a normally liquid petroleum-based composition includes at least one acoustic-wave device in contact with the petroleum-based composition for sensing or detecting the presence of constituents (e.g. paraffins or petroleum waxes) therein which solidify upon cooling of the petroleum-based composition below a cloud-point temperature. The acoustic-wave device can be a thickness-shear-mode device (also termed a quartz crystal microbalance), a surface-acoustic-wave device, an acoustic-plate-mode device or a flexural plate-wave device. Embodiments of the present invention can be used for measuring a cloud point, a pour point and/or a freeze point of the petroleum-based composition, and for determining a temperature characteristic of each point. Furthermore, measurements with the acoustic-wave sensor apparatus can be made off-line by using a sample having a particular petroleum-based composition; or in-situ with the petroleum-based composition contained within a pipeline or storage tank. The acoustic-wave sensor apparatus has uses in many different petroleum technology areas, including the recovery, transport, storage, refining and use of petroleum and petroleum-based products. 7 figs.

  8. Acoustic-wave sensor apparatus for analyzing a petroleum-based composition and sensing solidification of constituents therein

    DOEpatents

    Spates, James J.; Martin, Stephen J.; Mansure, Arthur J.

    1997-01-01

    An acoustic-wave sensor apparatus and method. The apparatus for analyzing a normally liquid petroleum-based composition includes at least one acoustic-wave device in contact with the petroleum-based composition for sensing or detecting the presence of constituents (e.g. paraffins or petroleum waxes) therein which solidify upon cooling of the petroleum-based composition below a cloud-point temperature. The acoustic-wave device can be a thickness-shear-mode device (also termed a quartz crystal mircrobalance), a surface-acoustic-wave device, an acoustic-plate-mode device or a flexural plate-wave device. Embodiments of the present invention can be used for measuring a cloud point, a pour point and/or a freeze point of the petroleum-based composition, and for determining a temperature characteristic of each point. Furthermore, measurements with the acoustic-wave sensor apparatus can be made off-line by using a sample having a particular petroleum-based composition; or in-situ with the petroleum-based composition contained within a pipeline or storage tank. The acoustic-wave sensor apparatus has uses in many different petroleum technology areas, including the recover transport, storage, refining and use of petroleum and petroleum-based products.

  9. Systems analysis for DSN microwave antenna holography

    NASA Technical Reports Server (NTRS)

    Rochblatt, D. J.

    1989-01-01

    Proposed systems for Deep Space Network (DSN) microwave antenna holography are analyzed. Microwave holography, as applied to antennas, is a technique which utilizes the Fourier Transform relation between the complex far-field radiation pattern of an antenna and the complex aperture field distribution to provide a methodology for the analysis and evaluation of antenna performance. Resulting aperture phase and amplitude distribution data are used to precisely characterize various crucial performance parameters, including panel alignment, subreflector position, antenna aperture illumination, directivity at various frequencies, and gravity deformation. Microwave holographic analysis provides diagnostic capacity as well as being a powerful tool for evaluating antenna design specifications and their corresponding theoretical models.

  10. Discriminative likelihood score weighting based on acoustic-phonetic classification for speaker identification

    NASA Astrophysics Data System (ADS)

    Suh, Youngjoo; Kim, Hoirin

    2014-12-01

    In this paper, a new discriminative likelihood score weighting technique is proposed for speaker identification. The proposed method employs a discriminative weighting of frame-level log-likelihood scores with acoustic-phonetic classification in the Gaussian mixture model (GMM)-based speaker identification. Experiments performed on the Aurora noise-corrupted TIMIT database showed that the proposed approach provides meaningful performance improvement with an overall relative error reduction of 15.8% over the maximum likelihood-based baseline GMM approach.

  11. Creating an extended focus image of a tilted object in Fourier digital holography.

    PubMed

    Paturzo, Melania; Ferraro, Pietro

    2009-10-26

    We present a new method to numerically reconstruct images on a tilted plane by digital holography in Fourier configuration. The proposed technique is based on a quadratic deformation of spatial coordinates of the digital hologram. By this approach we demonstrate that it is possible to recover the extended focus image (EFI) of a tilted object in a single reconstruction step from the deformed hologram.

  12. An acoustic-array based structural health monitoring technique for wind turbine blades

    NASA Astrophysics Data System (ADS)

    Aizawa, Kai; Poozesh, Peyman; Niezrecki, Christopher; Baqersad, Javad; Inalpolat, Murat; Heilmann, Gunnar

    2015-04-01

    This paper proposes a non-contact measurement technique for health monitoring of wind turbine blades using acoustic beamforming techniques. The technique works by mounting an audio speaker inside a wind turbine blade and observing the sound radiated from the blade to identify damage within the structure. The main hypothesis for the structural damage detection is that the structural damage (cracks, edge splits, holes etc.) on the surface of a composite wind turbine blade results in changes in the sound radiation characteristics of the structure. Preliminary measurements were carried out on two separate test specimens, namely a composite box and a section of a wind turbine blade to validate the methodology. The rectangular shaped composite box and the turbine blade contained holes with different dimensions and line cracks. An acoustic microphone array with 62 microphones was used to measure the sound radiation from both structures when the speaker was located inside the box and also inside the blade segment. A phased array beamforming technique and CLEAN-based subtraction of point spread function from a reference (CLSPR) were employed to locate the different damage types on both the composite box and the wind turbine blade. The same experiment was repeated by using a commercially available 48-channel acoustic ring array to compare the test results. It was shown that both the acoustic beamforming and the CLSPR techniques can be used to identify the damage in the test structures with sufficiently high fidelity.

  13. Spectrum interrogation of fiber acoustic sensor based on self-fitting and differential method.

    PubMed

    Fu, Xin; Lu, Ping; Ni, Wenjun; Liao, Hao; Wang, Shun; Liu, Deming; Zhang, Jiangshan

    2017-02-20

    In this article, we propose an interrogation method of fiber acoustic sensor to recover the time-domain signal from the sensor spectrum. The optical spectrum of the sensor will show a ripple waveform when responding to acoustic signal due to the scanning process in a certain wavelength range. The reason behind this phenomenon is the dynamic variation of the sensor spectrum while the intensity of different wavelength is acquired at different time in a scanning period. The frequency components can be extracted from the ripple spectrum assisted by the wavelength scanning speed. The signal is able to be recovered by differential between the ripple spectrum and its self-fitted curve. The differential process can eliminate the interference caused by environmental perturbations such as temperature or refractive index (RI), etc. The proposed method is appropriate for fiber acoustic sensors based on gratings or interferometers. A long period grating (LPG) is adopted as an acoustic sensor head to prove the feasibility of the interrogation method in experiment. The ability to compensate the environmental fluctuations is also demonstrated.

  14. A self-mixing based ring-type fiber-optic acoustic sensor

    NASA Astrophysics Data System (ADS)

    Wang, Lutang; Wu, Chunxu; Fang, Nian

    2014-07-01

    A novel, simple fiber-optic acoustic sensor consisting of a self-mixing effect based laser source and a ring-type interferometer is presented. With weak external optical feedbacks, the acoustic wave signals can be detected by measuring the changes of oscillating frequency of the laser diode, induced by the disturbances of sensing fiber, with the ring-type interferometer. The operation principles of the sensor system are explored in-depth and the experimental researches are carried out. The acoustic wave signals produced by various actions, such as by pencil broken, mental pin free falling and PZT are detected for evaluating the sensing performances of the experimental system. The investigation items include the sensitivity as well as frequency responses of the sensor system. An experiment for the detection of corona discharges is carried out, which occur in a high-voltage environment between two parallel copper electrodes, under different humidity levels. The satisfied experimental results are obtained. These experimental results well prove that our proposed sensing system has very high sensitivity and excellent high frequency responses characteristics in the detections of weak, high-frequency acoustic wave signals.

  15. SU-8 photoresist and SU-8 based nanocomposites for broadband acoustical matching at 1 GHz

    NASA Astrophysics Data System (ADS)

    Ndieguene, A.; Campistron, P.; Carlier, J.; Wang, S.; Callens-Debavelaere, D.; Nongaillard, B.

    2009-11-01

    So as to integrate acoustic functions in BioMEMS using 1 GHz ZnO transducers deposited on silicon substrates, acoustic waves propagation through the silicon substrate and its transmission in water needs to be maximized (the insertion losses at the Si / water interface are about 6dB). In the context of integration, it is interesting for mechanical impedance matching to use photosensitive materials such as SU-8 so that patterns may be obtained. Nanocomposite materials based on SU-8 mixed with nanoparticles having adequate impedances were fabricated. These new materials are characterized in terms of their acoustic velocity, impedance and attenuation. For this, the nanocomposite layers are deposited on the substrate by spin coating to obtain a thickness of about 10 μm, in order to separate acoustic echoes from the material (even if λ/4 layer thickness is lower than 1 μm). The insertion losses of the device immersed in water can be simulated as a function of frequency for a given reflection coefficient between the silicon substrate and the photoresist. The characteristics of some nanocomposites made with SU-8 and various concentrations of nanoparticles like Ti02, SrTiO3 or W have been determined.

  16. AlScN thin film based surface acoustic wave devices with enhanced microfluidic performance

    NASA Astrophysics Data System (ADS)

    Wang, W. B.; Fu, Y. Q.; Chen, J. J.; Xuan, W. P.; Chen, J. K.; Wang, X. Z.; Mayrhofer, P.; Duan, P. F.; Bittner, A.; Schmid, U.; Luo, J. K.

    2016-07-01

    This paper reports the characterization of scandium aluminum nitride (Al1-x Sc x N, x  =  27%) films and discusses surface acoustic wave (SAW) devices based on them. Both AlScN and AlN films were deposited on silicon by sputtering and possessed columnar microstructures with (0 0 0 2) crystal orientation. The AlScN/Si SAW devices showed improved electromechanical coupling coefficients (K 2, ~2%) compared with pure AlN films (<0.5%). The performance of the two types of devices was also investigated and compared, using acoustofluidics as an example. The AlScN/Si SAW devices achieved much lower threshold powers for the acoustic streaming and pumping of liquid droplets, and the acoustic streaming and pumping velocities were 2  ×  and 3  ×  those of the AlN/Si SAW devices, respectively. Mechanical characterization showed that the Young’s modulus and hardness of the AlN film decreased significantly when Sc was doped, and this was responsible for the decreased acoustic velocity and resonant frequency, and the increased temperature coefficient of frequency, of the AlScN SAW devices.

  17. The acoustic environment of intensive care wards based on long period nocturnal measurements.

    PubMed

    Xie, Hui; Kang, Jian

    2012-01-01

    The patients in the Intensive Care Units are often exposed to excessive levels of noise and activities. They can suffer from sleep disturbance, especially at night, but they are often too ill to cope with the poor environment. This article investigates the acoustic environment of typical intensive care wards in the UK, based on long period nocturnal measurements, and examines the differences between singlebed and multibed wards, using statistical analysis. It has been shown that the acoustic environment differs significantly every night. There are also significant differences between the noise levels in the singlebed and multibed wards, where acoustic ceilings are present. Despite the similar background noises in both ward types, more intrusive noises tend to originate from the multibed wards, while more extreme sounds are likely to occur in the single wards. The sound levels in the measured wards for each night are in excess of the World Health Organization's (WHO) guide levels by at least 20 dBA, dominantly at the middle frequencies. Although the sound level at night varies less than that in the daytime, the nocturnal acoustic environment is not dependant on any specific time, thus neither the noisiest nor quietest period can be determined. It is expected that the statistical analysis of the collected data will provide essential information for the development of relevant guidelines and noise reduction strategies.

  18. Acoustic Biometric System Based on Preprocessing Techniques and Linear Support Vector Machines

    PubMed Central

    del Val, Lara; Izquierdo-Fuente, Alberto; Villacorta, Juan J.; Raboso, Mariano

    2015-01-01

    Drawing on the results of an acoustic biometric system based on a MSE classifier, a new biometric system has been implemented. This new system preprocesses acoustic images, extracts several parameters and finally classifies them, based on Support Vector Machine (SVM). The preprocessing techniques used are spatial filtering, segmentation—based on a Gaussian Mixture Model (GMM) to separate the person from the background, masking—to reduce the dimensions of images—and binarization—to reduce the size of each image. An analysis of classification error and a study of the sensitivity of the error versus the computational burden of each implemented algorithm are presented. This allows the selection of the most relevant algorithms, according to the benefits required by the system. A significant improvement of the biometric system has been achieved by reducing the classification error, the computational burden and the storage requirements. PMID:26091392

  19. Acoustic Biometric System Based on Preprocessing Techniques and Linear Support Vector Machines.

    PubMed

    del Val, Lara; Izquierdo-Fuente, Alberto; Villacorta, Juan J; Raboso, Mariano

    2015-06-17

    Drawing on the results of an acoustic biometric system based on a MSE classifier, a new biometric system has been implemented. This new system preprocesses acoustic images, extracts several parameters and finally classifies them, based on Support Vector Machine (SVM). The preprocessing techniques used are spatial filtering, segmentation-based on a Gaussian Mixture Model (GMM) to separate the person from the background, masking-to reduce the dimensions of images-and binarization-to reduce the size of each image. An analysis of classification error and a study of the sensitivity of the error versus the computational burden of each implemented algorithm are presented. This allows the selection of the most relevant algorithms, according to the benefits required by the system. A significant improvement of the biometric system has been achieved by reducing the classification error, the computational burden and the storage requirements.

  20. Is holography ready for yet another life? or make holography great again

    NASA Astrophysics Data System (ADS)

    Trolinger, James D.

    2016-08-01

    Holographic metrology, unlike most other applications of holography, has always thrived and continues to thrive by continuously incorporating new supporting technologies that make it more powerful and useful. Successes, failures, lives, and deaths are examined and recognized as evolutionary steps that position the field where opportunities are as great and as many as ever. This is a story of that evolution. Comparisons and analogies with other applications of holography such as data storage, archiving, the arts, entertainment, advertising, and security and their evolution are interesting. Critical events, successes, mistakes, and coincidences represent milestones of abandonment or failure to deliver in many holography communities that followed a different evolutionary path. Events and new technical developments continue to emerge in supporting fields that can revive and expand all holography applications. New opportunities are described with encouragement to act on them and take some risks. Don't wait until all of the required technology and hardware are available, because good scientists always act before then. The paper is about "making holography great again" and your opportunity to be a part of the upcoming revolution. Although the discussion focuses on holographic metrology, the same principles should apply to other holography communities.

  1. Fast characterization of aluminum plates with TV-holography measurements of the frequency spectrum of multimode, quasi- monochromatic Lamb waves.

    PubMed

    Deán-Ben, X Luís; Trillo, Cristina; Doval, Angel F; Fernández, José L

    2011-06-01

    We introduce a novel approach for measuring the frequency spectrum of Lamb waves and, subsequently, for obtaining the thickness and the bulk wave velocities of isotropic, homogeneous plates. It is based on Fourier transforming a set of spatial and temporal samples of the acoustic displacement but, in contrast to the traditional approach that employs dense temporal sampling and a reduced set of spatial sampling locations, our data set is a sequence of 2-D high-resolution maps of the instantaneous out-of-plane displacement obtained with TV holography. We have devised three variants to obtain a set of points of the wavenumber-frequency space, based, respectively, on the spatial (1-D or 2-D) and on the spatio-temporal (3-D) Fourier transforms. The whole process to obtain these points can be easily automated and substantial time savings can be achieved, compared with other full-field techniques that require human intervention or with pointwise scanned probes. Experimental demonstration of the three variants with quasimonochromatic multimode Lamb waves in aluminum plates is presented. The characteristic parameters of the plates are calculated by fitting the theoretical model to the experimental points of the frequency spectrum. The analysis of the uncertainties shows that the accuracy of the method is only slightly lower than the accuracy of a previously reported method based on measuring the wavelength of single-modes, for which the data acquisition procedure is much slower.

  2. Adaptive phase calibration of a microphone array for acoustic holography.

    PubMed

    Teal, Paul D; Poletti, Mark A

    2010-04-01

    Previous work has indicated that a limitation on the performance of a circular microphone array for holographic sound field recording at low frequencies is phase mismatch between the microphones in the array. At low frequencies these variations become more significant than at mid-range and high frequencies because the high order phase mode responses at low frequencies are lower in amplitude. This paper demonstrates the feasibility of a "self-calibration" method. The basis of the calibration is to estimate the location of one or more wide-band sources using mid-range frequencies and to use this source location information to perform correction to the array at low frequencies. In its simplest form the calibration must be performed in an anechoic environment, since multipath effects at widely differing frequencies are uncorrelated. The approach is first demonstrated in such an environment using recordings from an array of high quality microphones. The technique is then extended to an adaptive calibration that can be used in an environment that is somewhat reverberant. The validity of the adaptive approach is demonstrated using recordings from an array of inexpensive microphones.

  3. A modal test method using sound pressure transducers based on vibro-acoustic reciprocity

    NASA Astrophysics Data System (ADS)

    Zhu, W. D.; Liu, J. M.; Xu, Y. F.; Ying, H. Q.

    2014-06-01

    A modal test method that uses sound pressure transducers at fixed locations and an impact hammer roving over a test structure is developed in this work. Since sound pressure transducers are used, the current method deals with a coupled structural-acoustic system. Based on the vibro-acoustic reciprocity, the method is equivalent to one, where acoustic excitations at fixed locations are given and the resulting acceleration of the test structure is measured. The current method can eliminate mass loading due to use of accelerometers, which can destroy existence of repeated or close natural frequencies of a symmetric structure. It can also avoid effects of a nodal line of a mode and an inactive area of a local mode, and measure all the out-of-plane modes within a frequency range of interest, including global and local ones. The coupling between the structure and the acoustic field in a structural-acoustic system introduces asymmetry in the model formulation. An equivalent state space formulation is used for a damped structural-acoustic system and the associated eigenvalue problem is derived. The biorthonormality relations between the left and right eigenvectors and the relations between the structural and acoustic components in the left and right eigenvectors are proved. The frequency response functions associated with the current method are derived and their physical meanings are explained. The guidelines for using the current method, including the types of structures that are suitable for the method, the positions of the sound pressure transducers, and the orientation of the test structure relative to the transducers, are provided. Modal tests were carried out on an automotive disk brake using the traditional and current methods, where multiple accelerometers and microphones were used to measure its dynamic responses induced by impacts, respectively. The differences between the measured natural frequencies using the current method and those from the finite element

  4. Evaluation of Midwater Trawl Selectivity and its Influence on Acoustic-Based Fish Population Surveys

    NASA Astrophysics Data System (ADS)

    Williams, Kresimir

    Trawls are used extensively during fisheries abundance surveys to derive estimates of fish density and, in the case of acoustic-based surveys, to identify acoustically sampled fish populations. However, trawls are selective in what fish they retain, resulting in biased estimates of density, species, and size compositions. Selectivity of the midwater trawl used in acoustic-based surveys of walleye pollock (Theragra chalcogramma) was evaluated using multiple methods. The effects of trawl selectivity on the acoustic-based survey abundance estimates and the stock assessment were evaluated for the Gulf of Alaska walleye pollock population. Selectivity was quantified using recapture, or pocket, nets attached to the outside of the trawl. Pocket net catches were modeled using a hierarchical Bayesian model to provide uncertainty in selectivity parameter estimates. Significant under-sampling of juvenile pollock by the midwater trawl was found, with lengths at 50% retention ranging from 14--26 cm over three experiments. Escapement was found to be light dependent, with more fish escaping in dark conditions. Highest escapement rates were observed in the aft of the trawl near to the codend though the bottom panel of the trawl. The behavioral mechanisms involved in the process of herding and escapement were evaluated using stereo-cameras, a DIDSON high frequency imaging sonar, and pocket nets. Fish maintained greater distances from the trawl panel during daylight, suggesting trawl modifications such as increased visibility of netting materials may evoke stronger herding responses and increased retention of fish. Selectivity and catchability of pollock by the midwater trawl was also investigated using acoustic density as an independent estimate of fish abundance to compare with trawl catches. A modeling framework was developed to evaluate potential explanatory factors for selectivity and catchability. Selectivity estimates were dependent on which vessel was used for the survey

  5. Compact transformable acoustic logic gates for broadband complex Boolean operations based on density-near-zero metamaterials

    NASA Astrophysics Data System (ADS)

    Zhang, Ting; Cheng, Ying; Yuan, Bao-Guo; Guo, Jian-Zhong; Liu, Xiao-Jun

    2016-05-01

    The extraordinary transmission in density-near-zero (DNZ) acoustic metamaterials (AMs) provides possibilities to manipulate acoustic signals with extremely large effective phase velocity and wavelength. Here, we report compact transformable acoustic logic gates with a subwavelength size as small as 0.82λ based on DNZ AMs. The basic acoustic logic gates, composed of a tri-port structure filled with space-coiling DNZ AMs, enable precise direct linear interference of input signals with considerably small phase lag and wavefront distortion. We demonstrate both theoretically and experimentally the basic Boolean logic operations such as OR, AND, XOR, and NOT with wide operational frequency ranges and controllability, by adjusting the phase difference between two input signals. More complex logic calculus, such as "I1 + I2 × I3," are also realized by cascading of the basic logic gates. Our proposal provides diverse routes to construct devices for acoustic signal computing and manipulations.

  6. Performance evaluation of an acoustic indoor localization system based on a fingerprinting technique

    NASA Astrophysics Data System (ADS)

    Aloui, Nadia; Raoof, Kosai; Bouallegue, Ammar; Letourneur, Stephane; Zaibi, Sonia

    2014-12-01

    We present an acoustic location system that adopts the time of arrival of the path of maximum amplitude as a signature and estimates the target position through nonparametric kernel regression. The system was evaluated in experiments for two main configurations: a privacy-oriented configuration with code division multiple access operation and a centralized configuration with time division multiple access operation. The effects of the number and positions of sources on the performance of the privacy-oriented system was studied. Moreover, the effect of the number of fingerprint positions on the performance of both systems was investigated. Results showed that our privacy-oriented scheme provides an accuracy of 8.5 cm with 87% precision, whereas our centralized system provides an accuracy of 2.7 cm for 93% of measurements. A comparison between our privacy-oriented system and another acoustic location system based on code division multiple access operation and lateration was conducted on our test bench and revealed that the cumulative error distribution function of the fingerprint-based system is better than that of the lateration-based system. This result is similar to that found for Wi-Fi radio-based localization. However, our experiments are the first to demonstrate the detrimental effect that reverberation has on naive acoustic localization approaches.

  7. Synthetic optical holography for rapid nanoimaging

    PubMed Central

    Schnell, M.; Carney, P. S.; Hillenbrand, R.

    2014-01-01

    Holography has paved the way for phase imaging in a variety of wide-field techniques, including electron, X-ray and optical microscopy. In scanning optical microscopy, however, the serial fashion of image acquisition seems to challenge a direct implementation of traditional holography. Here we introduce synthetic optical holography (SOH) for quantitative phase-resolved imaging in scanning optical microscopy. It uniquely combines fast phase imaging, technical simplicity and simultaneous operation at visible and infrared frequencies with a single reference arm. We demonstrate SOH with a scattering-type scanning near-field optical microscope (s-SNOM) where it enables reliable quantitative phase-resolved near-field imaging with unprecedented speed. We apply these capabilities to nanoscale, non-invasive and rapid screening of grain boundaries in CVD-grown graphene, by recording 65 kilopixel near-field images in 26 s and 2.3 megapixel images in 13 min. Beyond s-SNOM, the SOH concept could boost the implementation of holography in other scanning imaging applications such as confocal microscopy. PMID:24651276

  8. Haptic Holography/Touching the Ethereal

    NASA Astrophysics Data System (ADS)

    Page, Michael

    2013-02-01

    Haptic Holography, was perhaps, first proposed by workers at MIT in the 90s. The Media Lab, headed up by Dr. Stephen Benton, with published papers by Wendy Plesiak and Ravi Pappuh. -1 Recent developments in both the technology of digital holography and haptics have made it practical to conduct further investigations. Haptic holography is auto-stereoscopic and provides co-axial viewing for the user. Haptic holography may find application in medical & surgical training and as a new form of synthetic reality for artists and designers. At OCAD's PHASE Lab (Prototypes for Holographic Art and Science Explorations) workers are exploring hybrid forms of augmented reality, that combine haptics, interactivity and auto-stereoscopic imagery. Conventional Haptic environments, while presenting a 3D physics environment, typically provide a 2D visual work/play space. Orienteering in such an environment creates an uncertain spatial relationship for the user. Our group creates 3d models from which we create holographic constructs. The same model is used to create the physics environment. The two models are super-imposed. The result: Holograms you can touch.

  9. Advanced technology development multi-color holography

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.

    1993-01-01

    This is the final report of the Multi-color Holography project. The comprehensive study considers some strategic aspects of multi-color holography. First, various methods of available techniques for accurate fringe counting are reviewed. These are heterodyne interferometry, quasi-heterodyne interferometry, and phase-shifting interferometry. Phase-shifting interferometry was found to be the most suitable for multi-color holography. Details of experimentation with a sugar solution are also reported where better than 1/200 of a fringe order measurement capability was established. Rotating plate glass phase shifter was used for the experimentation. The report then describes the possible role of using more than two wavelengths with special reference-to-object beam intensity ratio needs in multicolor holography. Some specific two- and three-color cases are also described in detail. Then some new analysis methods of the reconstructed wavefront are considered. These are deflectometry, speckle metrology, confocal optical signal processing, and phase shifting technique related applications. Finally, design aspects of an experimental breadboard are presented.

  10. Entangled States, Holography and Quantum Surfaces

    SciTech Connect

    Chapline, G F

    2003-08-13

    Starting with an elementary discussion of quantum holography, we show that entangled quantum states of qubits provide a ''local'' representation of the global geometry and topology of quantum Riemann surfaces. This representation may play an important role in both mathematics and physics. Indeed, the simplest way to represent the fundamental objects in a ''theory of everything'' may be as muti-qubit entangled states.

  11. "Hare and Hounds" Tests of Helioseismic Holography

    NASA Astrophysics Data System (ADS)

    Birch, A. C.; Parchevsky, K. V.; Braun, D. C.; Kosovichev, A. G.

    2011-08-01

    We use the output of numerical wave-propagation simulations as synthetic data for "hare and hounds" tests of helioseismic holography. In the simple non-magnetic models examined here, we show that when the inversion method includes a consistent treatment of the filtering applied during the data analysis the inversions for the subsurface sound speed are qualitatively correct.

  12. The effect of speaking context on spectral- and cepstral-based acoustic features of normal voice.

    PubMed

    Lowell, Soren Y; Hylkema, Jennifer A

    2016-01-01

    The effect of speaking context on four cepstral- and spectral-based acoustic measures was investigated in 20 participants with normal voice. Speakers produced three different continuous speaking tasks that varied in duration and phonemic content. Cepstral and spectral measures that can be validly derived from continuous speech were computed across the three speaking contexts. Cepstral peak prominence (CPP), low/high spectral ratio, and the standard deviation (SD) of the low/high spectral ratio did not significantly differ across speaking contexts, and correlations for the first two measures were strong among the three speaking tasks. The SD of the CPP showed significant task differences, and relationships between the speaking contexts were generally moderate. These findings suggest that in speakers with normal voice, the differing phonemic content across several frequently used speaking stimuli minimally impacted group means for three clinically relevant cepstral- and spectral-based acoustic measures.

  13. Energy-Based Acoustic Source Localization Methods: A Survey

    PubMed Central

    Meng, Wei; Xiao, Wendong

    2017-01-01

    Energy-based source localization is an important problem in wireless sensor networks (WSNs), which has been studied actively in the literature. Numerous localization algorithms, e.g., maximum likelihood estimation (MLE) and nonlinear-least-squares (NLS) methods, have been reported. In the literature, there are relevant review papers for localization in WSNs, e.g., for distance-based localization. However, not much work related to energy-based source localization is covered in the existing review papers. Energy-based methods are proposed and specially designed for a WSN due to its limited sensor capabilities. This paper aims to give a comprehensive review of these different algorithms for energy-based single and multiple source localization problems, their merits and demerits and to point out possible future research directions. PMID:28212281

  14. Energy-Based Acoustic Source Localization Methods: A Survey.

    PubMed

    Meng, Wei; Xiao, Wendong

    2017-02-15

    Energy-based source localization is an important problem in wireless sensor networks (WSNs), which has been studied actively in the literature. Numerous localization algorithms, e.g., maximum likelihood estimation (MLE) and nonlinear-least-squares (NLS) methods, have been reported. In the literature, there are relevant review papers for localization in WSNs, e.g., for distance-based localization. However, not much work related to energy-based source localization is covered in the existing review papers. Energy-based methods are proposed and specially designed for a WSN due to its limited sensor capabilities. This paper aims to give a comprehensive review of these different algorithms for energy-based single and multiple source localization problems, their merits and demerits and to point out possible future research directions.

  15. Sparsity-Based Representation for Classification Algorithms and Comparison Results for Transient Acoustic Signals

    DTIC Science & Technology

    2016-05-01

    large but correlated noise and signal interference (i.e., low-rank interference). Another contribution is the implementation of deep learning ...representation, low rank, deep learning 52 Tung-Duong Tran-Luu 301-394-3082Unclassified Unclassified Unclassified UU ii Approved for public release; distribution...is unlimited. Contents List of Figures v List of Tables vi 1. Introduction 1 1.1 Motivations 1 1.2 Sparsity-Based Representation for Transient Acoustic

  16. Development of an Acoustic Signal Analysis Tool “Auto-F” Based on the Temperament Scale

    NASA Astrophysics Data System (ADS)

    Modegi, Toshio

    The MIDI interface is originally designed for electronic musical instruments but we consider this music-note based coding concept can be extended for general acoustic signal description. We proposed applying the MIDI technology to coding of bio-medical auscultation sound signals such as heart sounds for retrieving medical records and performing telemedicine. Then we have tried to extend our encoding targets including vocal sounds, natural sounds and electronic bio-signals such as ECG, using Generalized Harmonic Analysis method. Currently, we are trying to separate vocal sounds included in popular songs and encode both vocal sounds and background instrumental sounds into separate MIDI channels. And also, we are trying to extract articulation parameters such as MIDI pitch-bend parameters in order to reproduce natural acoustic sounds using a GM-standard MIDI tone generator. In this paper, we present an overall algorithm of our developed acoustic signal analysis tool, based on those research works, which can analyze given time-based signals on the musical temperament scale. The prominent feature of this tool is producing high-precision MIDI codes, which reproduce the similar signals as the given source signal using a GM-standard MIDI tone generator, and also providing analyzed texts in the XML format.

  17. Analysis on accuracy improvement of rotor-stator rubbing localization based on acoustic emission beamforming method.

    PubMed

    He, Tian; Xiao, Denghong; Pan, Qiang; Liu, Xiandong; Shan, Yingchun

    2014-01-01

    This paper attempts to introduce an improved acoustic emission (AE) beamforming method to localize rotor-stator rubbing fault in rotating machinery. To investigate the propagation characteristics of acoustic emission signals in casing shell plate of rotating machinery, the plate wave theory is used in a thin plate. A simulation is conducted and its result shows the localization accuracy of beamforming depends on multi-mode, dispersion, velocity and array dimension. In order to reduce the effect of propagation characteristics on the source localization, an AE signal pre-process method is introduced by combining plate wave theory and wavelet packet transform. And the revised localization velocity to reduce effect of array size is presented. The accuracy of rubbing localization based on beamforming and the improved method of present paper are compared by the rubbing test carried on a test table of rotating machinery. The results indicate that the improved method can localize rub fault effectively.

  18. Accurate group velocity estimation for unmanned aerial vehicle-based acoustic atmospheric tomography.

    PubMed

    Rogers, Kevin J; Finn, Anthony

    2017-02-01

    Acoustic atmospheric tomography calculates temperature and wind velocity fields in a slice or volume of atmosphere based on travel time estimates between strategically located sources and receivers. The technique discussed in this paper uses the natural acoustic signature of an unmanned aerial vehicle as it overflies an array of microphones on the ground. The sound emitted by the aircraft is recorded on-board and by the ground microphones. The group velocities of the intersecting sound rays are then derived by comparing these measurements. Tomographic inversion is used to estimate the temperature and wind fields from the group velocity measurements. This paper describes a technique for deriving travel time (and hence group velocity) with an accuracy of 0.1% using these assets. This is shown to be sufficient to obtain highly plausible tomographic inversion results that correlate well with independent SODAR measurements.

  19. Investigation of a mercurous chloride acousto-optic cell based on longitudinal acoustic mode.

    PubMed

    Gupta, Neelam

    2009-03-01

    A number of spectral imagers using acousto-optic tunable filters (AOTFs) operating from the UV to the longwave infrared (LWIR) using KDP, MgF(2), TeO(2), and Tl(3)AsSe(3) crystals to cover different spectral regions have been developed. In the LWIR there is a lack of high quality acousto-optic (AO) materials. Mercurous halide (Hg(2)Cl(2) and Hg(2)Br(2)) crystals are highly anisotropic with a high AO figure of merit due to slow acoustic velocities and high photoelastic constants and are transparent over a wide spectral region from 0.35 to 20 mum for Hg(2)Cl(2) and from 0.4 to 30 mum for Hg(2)Br(2). AO modulators, deflectors, and AOTFs based on these crystals can operate over a wide spectral range. Single crystals of these materials are being grown and some prototype devices have been fabricated. Results are presented from device characterization for an AO cell fabricated in Hg(2)Cl(2) based on longitudinal acoustic mode propagation. This device was very useful in demonstrating the AO interaction as well as soundness of the transducer bonding technique. Acoustic phase velocity is calculated and measured, diffraction efficiency is obtained from experiments, and the AO figure of merit of the sample is evaluated.

  20. A statistical-based approach for acoustic tomography of the atmosphere.

    PubMed

    Kolouri, Soheil; Azimi-Sadjadi, Mahmood R; Ziemann, Astrid

    2014-01-01

    Acoustic travel-time tomography of the atmosphere is a nonlinear inverse problem which attempts to reconstruct temperature and wind velocity fields in the atmospheric surface layer using the dependence of sound speed on temperature and wind velocity fields along the propagation path. This paper presents a statistical-based acoustic travel-time tomography algorithm based on dual state-parameter unscented Kalman filter (UKF) which is capable of reconstructing and tracking, in time, temperature, and wind velocity fields (state variables) as well as the dynamic model parameters within a specified investigation area. An adaptive 3-D spatial-temporal autoregressive model is used to capture the state evolution in the UKF. The observations used in the dual state-parameter UKF process consist of the acoustic time of arrivals measured for every pair of transmitter/receiver nodes deployed in the investigation area. The proposed method is then applied to the data set collected at the Meteorological Observatory Lindenberg, Germany, as part of the STINHO experiment, and the reconstruction results are presented.

  1. Two-dimensional Phase Unwrapping for Digital Holography

    DTIC Science & Technology

    2012-09-01

    Two-dimensional Phase Unwrapping for Digital Holography by Neal K. Bambha, Justin R. Bickford, and Karl K. Klett, Jr. ARL-TR-6225...1197 ARL-TR-6225 September 2012 Two-dimensional Phase Unwrapping for Digital Holography Neal K. Bambha, Justin R. Bickford, and Karl K...2. REPORT TYPE Final 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Two-dimensional Phase Unwrapping for Digital Holography 5a. CONTRACT

  2. Display holography an SPIE critical review of technology

    NASA Astrophysics Data System (ADS)

    Benton, S. A.

    1985-01-01

    Various techniques used in holographic imagery are presented. The prominent features, potentials, and limitations of the laser transmission ('Leith and Upatnieks') holography, the white light transmission ('rainbow' or 'Benton') holography, and the reflection ('Denisyuk') holography methods are discused. Special consideration is given to the practical technique of holographic stereograms, which permits accurate production of three-dimensional, magnified and minified, images of moving objects or moving images, and which is part of all three classes of holographic methods.

  3. Computer holography by means of the laser diodes

    NASA Astrophysics Data System (ADS)

    Borodin, Arthur N.; Ilchenko, Volodymyr; Malov, Alexander N.; Sychevskiy, Alexey V.

    2007-02-01

    A computer holography is the optical hologram recording on the CCD-matrix with digital reconstruction of the 2Dimages for the different volume object cross-sections. The possibility to use compact semiconductor laser diodes in the computer holography for 3D-scene registration is experimentally proved in the D. Gabor's scheme. For off axis hologram recording the S. Benton's scheme for holography using is suggested.

  4. Acoustic metamaterial structures based on multi-frequency vibration absorbers

    NASA Astrophysics Data System (ADS)

    Pai, P. Frank; Peng, Hao

    2014-03-01

    This paper presents a new metamaterial beam based on multi-frequency vibration absorbers for broadband vibration absorption. The proposed metamaterial beam consists of a uniform isotropic beam and small two-mass spring-mass- damper subsystems at many locations along the beam to act as multi-frequency vibration absorbers. For an infinite metamaterial beam, governing equations of a unit cell are derived using the extended Hamilton principle. The existence of two stopbands is demonstrated using a model based on averaging material properties over a cell length and a model based on finite element modeling and the Bloch-Floquet theory for periodic structures. For a finite metamaterial beam, because these two idealized models cannot be used for finite beams and/or elastic waves having short wavelengths, a finite-element method is used for detailed modeling and analysis. The concepts of negative effective mass and effective stiffness and how the spring-mass-damper subsystem creates two stopbands are explained in detail. Numerical simulations reveal that the actual working mechanism of the proposed metamaterial beam is based on the concept of conventional mechanical vibration absorbers. For an incoming wave with a frequency in one of the two stopbands, the absorbers are excited to vibrate in their optical modes to create shear forces to straighten the beam and stop the wave propagation. For an incoming wave with a frequency outside of but between the two stopbands, it can be efficiently damped out by the damper with the second mass of each absorber. Hence, the two stopbands are connected into a wide stopband. Numerical examples validate the concept and show that the structure's boundary conditions do not have significant influence on the absorption of high-frequency waves. However, for absorption of low-frequency waves, the structure's boundary conditions and resonance frequencies and the location and spatial distribution of absorbers need to be considered in design, and it

  5. Spatial-temporal demodulation technique for heterodyne optical scanning holography

    NASA Astrophysics Data System (ADS)

    Liu, Jung-Ping; Luo, Dao-Zheng; Lu, Sheng-Hua

    2015-05-01

    In optical scanning holography (OSH), the object is raster scanned by a heterodyne fringe pattern. The light scattered from the object is detected by a photodetector. Traditionally, the photo-electric signal is demodulated by a dual-channel lock-in amplifier (LIA) to extract a complex hologram. The use of LIA complicates the detection module of the system and increases the cost, especially when the heterodyne frequency is high. In this paper, an alternative demodulation method called a spatial-temporal demodulation technique (STDT) is studied. In STDT, the photo-electric temporal signal is directly digitized as scanning lines. The spectrum of each scanning line is band-pass filtered to remove the zeroth-order term and the complex conjugate term. Finally, a complex hologram is obtained from the filtered spectrum. The first merit of STDT is that the phase of the demodulated complex hologram is insensitive to the modulation error. Thus it is easily applied to the applications of particle holography. Besides, the bandwidth of the zeroth-order term in STDT is narrow, which allows the system to be operated in a wide range of heterodyne frequency. This feature enables STDT-based OSH to be applied in low-cost and high-speed dynamic holographic imaging.

  6. Acoustic metamaterial panels based on multi frequency vibration absorbers

    NASA Astrophysics Data System (ADS)

    Shi, Chao; Sun, Hongwei; Hu, Xiaolei; Gu, Jinliang

    2016-04-01

    Presented here is a new metamaterial panel based on multi-frequency vibration absorbers for broadband vibration absorption. The proposed metamaterial panel consists of a uniform isotropic panel and small two-mass spring-mass-damper subsystem many locations along the panel to act as multi-frequency vibration absorbers. The existence of two stopbands is demonstrated using a model based on averaging material properties over a cell length and a model based on finite element modeling and the Bloch-Floquet theory for periodic structures. For a finite metamaterial panel, because these two idealized models can not be used for finite panels and/or elastic waves having short wavelengths, a finite-element method is used for detailed modeling and analysis. The concepts of negative effective stiffness is explained in detail. For an incoming wave with a frequency in one of the two stopbands, the absorbers are excited to vibrate in their optical modes to create shear forces to straighten the panel and stop the wave propagation. For an incoming wave with a frequency outside of but between the two stopbands, it can be efficiently damped out by the damper with these mass of each absorber. Hence, the two stopbands are connected in to a wide stopband. Numerical examples validate the concept and show that the structures boundary conditions do not have significant influence on the absorption of high-frequency waves. However, for absorption of low-frequency waves, the structures boundary conditions and resonance frequencies and the location and spatial distribution of absorbers need to be considered in design, and it is better to use heavier masses for absorbers.

  7. Underwater Acoustic Sensors Based on Fiber Bragg Gratings

    PubMed Central

    Campopiano, Stefania; Cutolo, Antonello; Cusano, Andrea; Giordano, Michele; Parente, Giuseppe; Lanza, Giuseppe; Laudati, Armando

    2009-01-01

    We report on recent results obtained with a fiber optic hydrophone based on the intensity modulation of the laser light in a FBG (Fiber Bragg Grating) under the influence of the sound pressure. In order to control the behavior of the hydrophone in terms of sensitivity and bandwidth, FBGs have been coated with proper materials, characterized by different elastic modulus and shapes. In particular, new experiments have been carried out using a cylindrical geometry with two different coating, showing that the sensitivity is not influenced by the shape but by the transversal dimension and the material characteristics of the coating. PMID:22408534

  8. Segment-based acoustic models for continuous speech recognition

    NASA Astrophysics Data System (ADS)

    Ostendorf, Mari; Rohlicek, J. R.

    1993-07-01

    This research aims to develop new and more accurate stochastic models for speaker-independent continuous speech recognition, by extending previous work in segment-based modeling and by introducing a new hierarchical approach to representing intra-utterance statistical dependencies. These techniques, which are more costly than traditional approaches because of the large search space associated with higher order models, are made feasible through rescoring a set of HMM-generated N-best sentence hypotheses. We expect these different modeling techniques to result in improved recognition performance over that achieved by current systems, which handle only frame-based observations and assume that these observations are independent given an underlying state sequence. In the fourth quarter of the project, we have completed the following: (1) ported our recognition system to the Wall Street Journal task, a standard task in the ARPA community; (2) developed an initial dependency-tree model of intra-utterance observation correlation; and (3) implemented baseline language model estimation software. Our initial results on the Wall Street Journal task are quite good and represent significantly improved performance over most HMM systems reporting on the Nov. 1992 5k vocabulary test set.

  9. Real-time RNN-based acoustic thermometry with feedback control

    NASA Astrophysics Data System (ADS)

    Hsu, Stephen J.; Nam, Joana H.; Fan, Liexiang; Brunke, Shelby S.; Sekins, K. Michael

    2017-03-01

    A major obstacle to the widespread adoption of HIFU therapy is the development of a suitable method of monitoring the a blation therapy in real-time. While MR-thermometry has emerged as a promising method for HIFU therapy monitoring, acoustic guidance has continuously been sought for reasons of cost and practicality. We have previously demonstrated the potential of acoustic thermometry, by using a recurrent neural network (RNN) to estimate changes in tissue temperature during HIFU ablation therapies. A limitation of this method is that an excessive therapeutic dose can cause multiple, non-linear changes within the ultrasound data, resulting in unreliable temperature estimates from the RNN. Accordingly, we propose a revised method of dosing wherein closed loop feedback is used to provide a controlled and specific dose; not only to ensure an efficacious lesion, but also to preserve the integrity of the ultrasound image, thereby producing accurate temperature estimates from the RNN. This investigation of controlling the thermal dose using feedback was performed on ex vivo bovine liver. The acoustic parameters used as inputs to the RNN were: changes in integrated backscatter intensity, thermal strain, and decorrelation. The therapeutic dose was delivered using a 1.1 MHz, 2D-array HIFU transducer transmitting at regular intervals during a 40-second dose. Interleaved between these regular HIFU dose intervals, volumetric ultrasound images were acquired on a Siemens ACUSON SC2000, with a 4Zlc probe. Feedback was introduced to the system by varying the HIFU duty cycle, in order to minimize the difference between a desired temperature curve (assigned a priori) and the estimated focal temperature values. Two methods were used for obtaining the focal temperature: the first was direct measurement using a 75-micron copper-constantan thermocouple embedded within the liver sample, and the second was temperature estimation as calculated from the RNN-based output temperatures

  10. High-speed parallel phase-shifting digital holography system using special-purpose computer for image reconstruction

    NASA Astrophysics Data System (ADS)

    Kakue, Takashi; Shimobaba, Tomoyoshi; Ito, Tomoyoshi

    2015-05-01

    We report a high-speed parallel phase-shifting digital holography system using a special-purpose computer for image reconstruction. Parallel phase-shifting digital holography is a technique capable of single-shot phase-shifting interferometry. This technique records information of multiple phase-shifted holograms required for calculation of phase-shifting interferometry with a single shot by using space-division multiplexing. This technique needs image-reconstruction process for a huge amount of recorded holograms. In particular, it takes a long time to calculate light propagation based on fast Fourier transform in the process and to obtain a motion picture of a dynamically and fast moving object. Then we designed a special-purpose computer for accelerating the image-reconstruction process of parallel phase-shifting digital holography. We developed a special-purpose computer consisting of VC707 evaluation kit (Xilinx Inc.) which is a field programmable gate array board. We also recorded holograms consisting of 128 × 128 pixels at a frame rate of 180,000 frames per second by the constructed parallel phase-shifting digital holography system. By applying the developed computer to the recorded holograms, we confirmed that the designed computer can accelerate the calculation of image-reconstruction process of parallel phase-shifting digital holography ~50 times faster than a CPU.

  11. Generalized Discrete Model of Systems with Distributed Feedback Based on Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Sveshnikov, B. V.; Bagdasaryan, A. S.

    2016-11-01

    We have developed a self-consistent physical model that improves the accuracy of calculating the characteristics of the devices based on both surface and pseudosurface acoustic waves. The model is free from restrictions inherent in the well-known method of coupled modes and other phenomenological methods for studying distributed systems. The compact relationships describing all the characteristics of the acoustoelectric transducers of all types with allowance for the possible directionality of their radiation and its propagation loss are obtained using analytical solution of the difference equations. The method for determining the spatial orientation of the elastic-polarization ellipse in an anisotropic crystal, which allows one to unambiguously calculate the phase shift between the oscillations of two coupled dynamical subsystems, i.e., elastic displacements and the corresponding electric field, is proposed. The obtained results, which considerably facilitate the task of fast and accurate design of various devices on the basis of surface and pseudosurface acoustic waves, are valid in the general case for any frequency, including the harmonics of the frequency of the fundamental acoustic synchronism.

  12. Acoustics and temperature based NDT for damage assessment of concrete masonry system subjected to cyclic loading

    NASA Astrophysics Data System (ADS)

    Khan, Fuad; Bartoli, Ivan; Rajaram, Satish; Vanniamparambil, Prashanth A.; Kontsos, Antonios; Bolhassani, Mohammad; Hamid, Ahmad

    2014-04-01

    This paper represents a hybrid non-destructive testing (HNDT) approach based on infrared thermography (IRT), acoustic emission (AE) and ultrasonic (UT) techniques for effective damage quantification of partially grouted concrete masonry walls (CMW). This integrated approach has the potential to be implemented for the health monitoring of concrete masonry systems. The implementation of this hybrid approach assists the cross validation of in situ recorded information for structural damage assessment. In this context, NDT was performed on a set of partially grouted CMW subjected to cyclic loading. Acoustic emission (AE) signals and Infrared thermography (IRT) images were recorded during each cycle of loading while the ultrasonic (UT) tests were performed in between each loading cycle. Four accelerometers, bonded at the toe of the wall, were used for recording waveforms for both passive (AE) and active (UT) acoustics. For the active approach, high frequency stress waves were generated by an instrumented hammer and the corresponding waveforms were recorded by the accelerometers. The obtained AE, IRT, and UT results were correlated to visually confirm accumulated progressive damage throughout the loading history. Detailed post-processing of these results was performed to characterize the defects at the region of interest. The obtained experimental results demonstrated the potential of the methods to detect flaws on monitored specimens; further experimental investigations are planned towards the quantitative use of these NDT methods.

  13. Analyzing the validity of a DFT-based improved acoustic OFDM transmission along rotating simulated drillstring

    NASA Astrophysics Data System (ADS)

    Cheng, Li; Jinfeng, Chang; Shangchun, Fan; Jun, Yang

    2016-12-01

    In the oil industry, drillstring can be used as a transmission medium to send downhole information via a modulated compressional acoustic wave. However, the accompanied reverberation is a major constraint in the transmission rate and distance because of the multipath fading caused by the heterogeneous drillstring. In combination with discrete Fourier transform-spread (DFT-S) mapping/demapping, high-power amplitude squeezing and DFT-based least squares channel estimation methods, an improved orthogonal frequency division multiplexing (OFDM) scheme is proposed in this paper to overcome the symbol interference inherent in the drillstring multipath channel and reduce the peak-to-average power ratio of the signal. Then an experimental rig is established by using a rotatable electromagnetic vibration exciter and a piezoelectric accelerometer arranged at the position closer to acoustic impedance terminal along a 6.3-m periodic simulated drillstring. The OFDM data sequences at a data rate of 200 bit/s over a limited bandwidth of 140 Hz are applied to the rotating simulated drillstring. The experimental results show that the proposed scheme using QPSK modulation can offer an error-free acoustic communication at rotation speeds up to 90 r/min.

  14. Acoustic cardiac signals analysis: a Kalman filter-based approach.

    PubMed

    Salleh, Sheik Hussain; Hussain, Hadrina Sheik; Swee, Tan Tian; Ting, Chee-Ming; Noor, Alias Mohd; Pipatsart, Surasak; Ali, Jalil; Yupapin, Preecha P

    2012-01-01

    Auscultation of the heart is accompanied by both electrical activity and sound. Heart auscultation provides clues to diagnose many cardiac abnormalities. Unfortunately, detection of relevant symptoms and diagnosis based on heart sound through a stethoscope is difficult. The reason GPs find this difficult is that the heart sounds are of short duration and separated from one another by less than 30 ms. In addition, the cost of false positives constitutes wasted time and emotional anxiety for both patient and GP. Many heart diseases cause changes in heart sound, waveform, and additional murmurs before other signs and symptoms appear. Heart-sound auscultation is the primary test conducted by GPs. These sounds are generated primarily by turbulent flow of blood in the heart. Analysis of heart sounds requires a quiet environment with minimum ambient noise. In order to address such issues, the technique of denoising and estimating the biomedical heart signal is proposed in this investigation. Normally, the performance of the filter naturally depends on prior information related to the statistical properties of the signal and the background noise. This paper proposes Kalman filtering for denoising statistical heart sound. The cycles of heart sounds are certain to follow first-order Gauss-Markov process. These cycles are observed with additional noise for the given measurement. The model is formulated into state-space form to enable use of a Kalman filter to estimate the clean cycles of heart sounds. The estimates obtained by Kalman filtering are optimal in mean squared sense.

  15. Multipoint dynamically reconfigure adaptive distributed fiber optic acoustic emission sensor (FAESense) system for condition based maintenance

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar; Prohaska, John; Kempen, Connie; Esterkin, Yan; Sun, Sunjian; Krishnaswamy, Sridhar

    2010-09-01

    This paper describes preliminary results obtained under a Navy SBIR contract by Redondo Optics Inc. (ROI), in collaboration with Northwestern University towards the development and demonstration of a next generation, stand-alone and fully integrated, dynamically reconfigurable, adaptive fiber optic acoustic emission sensor (FAESense™) system for the in-situ unattended detection and localization of shock events, impact damage, cracks, voids, and delaminations in new and aging critical infrastructures found in ships, submarines, aircraft, and in next generation weapon systems. ROI's FAESense™ system is based on the integration of proven state-of-the-art technologies: 1) distributed array of in-line fiber Bragg gratings (FBGs) sensors sensitive to strain, vibration, and acoustic emissions, 2) adaptive spectral demodulation of FBG sensor dynamic signals using two-wave mixing interferometry on photorefractive semiconductors, and 3) integration of all the sensor system passive and active optoelectronic components within a 0.5-cm x 1-cm photonic integrated circuit microchip. The adaptive TWM demodulation methodology allows the measurement of dynamic high frequnency acoustic emission events, while compensating for passive quasi-static strain and temperature drifts. It features a compact, low power, environmentally robust 1-inch x 1-inch x 4-inch small form factor (SFF) package with no moving parts. The FAESense™ interrogation system is microprocessor-controlled using high data rate signal processing electronics for the FBG sensors calibration, temperature compensation and the detection and analysis of acoustic emission signals. Its miniaturized package, low power operation, state-of-the-art data communications, and low cost makes it a very attractive solution for a large number of applications in naval and maritime industries, aerospace, civil structures, the oil and chemical industry, and for homeland security applications.

  16. Statistical weighting of model-based optoacoustic reconstruction for minimizing artefacts caused by strong acoustic mismatch

    NASA Astrophysics Data System (ADS)

    Deán-Ben, X. Luís; Razansky, Daniel; Ntziachristos, Vasilis

    2011-03-01

    A modified quantitative inversion algorithm is presented that minimizes the effects of internal acoustic reflections or scattering in tomographic optoacoustic images. The inversion procedure in our model-based algorithm consists in solving a linear system of equations in which each individual equation corresponds to a given position of the acoustic transducer and to a given time instant. Thus, the modification that we propose in this work consists in weighting each equation of the linear system with the probability that the measured wave is not distorted by reflection or scattering phenomena. We show that the probability that a reflected or scattered wave is detected at a given position and at a given instant is approximately proportional to the size of the area in which the original wave could have been generated, which is dependent on the position of the transducer and on the time instant, so that such probability can be used to weight each equation of the linear system. Thereby, the contribution of the waves that propagate directly to the transducer to the reconstructed images is emphasized. We experimentally test the proposed inversion algorithm with tissue-mimicking agar phantoms in which air-gaps are included to cause reflections of the acoustic waves. The tomographic reconstructions obtained with the modification proposed herein show a clear reduction of the artefacts due to these acoustic phenomena with respect to the reconstructions yielded with the original algorithm. This performance is directly related to in-vivo small animal imaging applications involving imaging in the presence of bones, lungs, and other highly mismatched organs.

  17. Southeast Alaska Acoustic Measurement Facility (SEAFAC) environmental data base review, evaluation, and upgrade

    SciTech Connect

    Strand, J.A.; Skalski, J.R.; Faulkner, L.L.; Rodman, C.W.; Carlile, D.W.; Ecker, R.M.; Nicholls, A.K.; Ramsdell, J.V.; Scott, M.J.

    1986-04-01

    This report summarizes the principal issues of public concern, the adequacy of the environmental data base to answer the issues of concern, and the additional data collection required to support a National Environmental Policy Act (NEPA) review of the proposed Southeast Alaska Acoustic Measurement Facility (SEAFAC). The report is based on a review of the readily available environmental literature and a site visit. Representatives of local, state, and federal agencies were also interviewed for their personal insights and concerns not discovered during the literature review.

  18. Acoustic imaging in application to reconstruction of rough rigid surface with airborne ultrasound waves

    NASA Astrophysics Data System (ADS)

    Krynkin, A.; Dolcetti, G.; Hunting, S.

    2017-02-01

    Accurate reconstruction of the surface roughness is of high importance to various areas of science and engineering. One important application of this technology is for remote monitoring of open channel flows through observing its dynamic surface roughness. In this paper a novel airborne acoustic method of roughness reconstruction is proposed and tested with a static rigid rough surface. This method is based on the acoustic holography principle and Kirchhoff approximation which make use of acoustic pressure data collected at multiple receiver points spread along an arch. The Tikhonov regularisation and generalised cross validation technique are used to solve the underdetermined system of equations for the acoustic pressures. The experimental data are collected above a roughness created with a 3D printer. For the given surface, it is shown that the proposed method works well with the various number of receiver positions. In this paper, the tested ratios between the number of surface points at which the surface elevation can be reconstructed and number of receiver positions are 2.5, 5, and 7.5. It is shown that, in a region comparable with the projected size of the main directivity lobe, the method is able to reconstruct the spatial spectrum density of the actual surface elevation with the accuracy of 20%.

  19. High precision phase-shifting electron holography

    PubMed

    Yamamoto; Kawajiri; Tanji; Hibino; Hirayama

    2000-01-01

    Today's information-oriented society requires high density and high quality magnetic recording media. The quantitative observation of fine magnetic structures by electron holography is greatly anticipated in the development of such new recording materials. However, the magnetic fields around particles <50 nm have not been observed, because the fields are too weak to observe in the usual way. Here we present a highly precise phase measurement technique: improved phase-shifting electron holography. Using this method, the electric field around a charged polystyrene latex particle (100 nm in diameter) and the magnetic field around iron particles (30 nm in diameter) are observed precisely. A precision of the reconstructed phase image of 2pi/300 rad is achieved in the image of the latex particle.

  20. Imaging nanoparticles in cells by nanomechanical holography

    SciTech Connect

    Tetard, Laurene; Passian, Ali; Venmar, Katherine T; Lynch, Rachel M; Voy, Brynn H; Shekhawat, Gajendra; Dravid, Vinayak; Thundat, Thomas George

    2008-06-01

    Nanomaterials have potential medical applications, for example in the area of drug delivery, and their possible adverse effects and cytotoxicity are curently receiving attention1,2. Inhalation of nanoparticles is of great concern, because nanoparticles can be easily aerosolized. Imaging techniques that can visualize local populations of nanoparticles at nanometre resolution within the structures of cells are therefore important3. Here we show that cells obtained from mice exposed to single-walled carbon nanohorns can be probed using a scanning probe microscopy technique called scanning near field ultrasonic holography. The nanohorns were observed inside the cells, and this was further confirmed using micro Raman spectroscopy. Scanning near field ultrasonic holography is a useful technique for probing the interactions of engineered nanomaterials in biological systems, which will greatly benefit areas in drug delivery and nanotoxicology.

  1. AUV Positioning Method Based on Tightly Coupled SINS/LBL for Underwater Acoustic Multipath Propagation.

    PubMed

    Zhang, Tao; Shi, Hongfei; Chen, Liping; Li, Yao; Tong, Jinwu

    2016-03-11

    This paper researches an AUV (Autonomous Underwater Vehicle) positioning method based on SINS (Strapdown Inertial Navigation System)/LBL (Long Base Line) tightly coupled algorithm. This algorithm mainly includes SINS-assisted searching method of optimum slant-range of underwater acoustic propagation multipath, SINS/LBL tightly coupled model and multi-sensor information fusion algorithm. Fuzzy correlation peak problem of underwater LBL acoustic propagation multipath could be solved based on SINS positional information, thus improving LBL positional accuracy. Moreover, introduction of SINS-centered LBL locating information could compensate accumulative AUV position error effectively and regularly. Compared to loosely coupled algorithm, this tightly coupled algorithm can still provide accurate location information when there are fewer than four available hydrophones (or within the signal receiving range). Therefore, effective positional calibration area of tightly coupled system based on LBL array is wider and has higher reliability and fault tolerance than loosely coupled. It is more applicable to AUV positioning based on SINS/LBL.

  2. Digital holography techniques for optical interference

    NASA Astrophysics Data System (ADS)

    Perez-Garcia, Benjamin; Gossman, David; Hernandez-Aranda, Raul I.; Forbes, Andrew

    2016-09-01

    In this work we revisit Young's experiment and show how it can be done with digital holography. We study different properties of light and show that depending on how light interferes, fringe patterns in other observables arise. We explain this conceptually and demonstrate how this can be implemented experimentally. We aid the reader with a tutorial-like approach and provide the necessary tools to easily perform the experiments.

  3. Quantitative phase microscopy with asynchronous digital holography.

    PubMed

    Chalut, Kevin J; Brown, William J; Wax, Adam

    2007-03-19

    We demonstrate a new method of measuring quantitative phase in imaging of biological materials. This method, asynchronous digital holography, employs knowledge of a moving fringe created by acousto-optic modulators to execute phase-shifting interferometry using two near-simultaneous interferograms. The method can be used to obtain quantitative phase images of dynamic biological samples on millisecond time scales. We present results on a standard sample, and on live cell samples.

  4. Medical Holography for Basic Anatomy Training

    DTIC Science & Technology

    2013-12-01

    current holographic technology is able to present high quality auto-stereoscopic (no-glasses) 30 visuals. Holography began in the 1940s, when Dennis ... Gabor invented the hologram and won the Nobel Prize for the achievement ( Gabor , 1948). Significant advances occurred when researchers created the...Investigating Geospatial Holograms for Special Weapons and Tactics Teams. Cartographic Perspectives, (63), 5-19. Gabor , D. (1948). A new

  5. Chaos in AdS2 Holography

    NASA Astrophysics Data System (ADS)

    Jensen, Kristan

    2016-09-01

    We revisit two-dimensional holography with the Sachdev-Ye-Kitaev models in mind. Our main result is to rewrite a generic theory of gravity near a two-dimensional anti-de Sitter spacetime throat as a novel hydrodynamics coupled to the correlation functions of a conformal quantum mechanics. This gives a prescription for the computation of n -point functions in the dual quantum mechanics. We thereby find that the dual is maximally chaotic.

  6. Multidimensional imaging using compressive Fresnel holography.

    PubMed

    Horisaki, Ryoichi; Tanida, Jun; Stern, Adrian; Javidi, Bahram

    2012-06-01

    We propose a generalized framework for single-shot acquisition of multidimensional objects using compressive Fresnel holography. A multidimensional object with spatial, spectral, and polarimetric information is propagated with the Fresnel diffraction, and the propagated signal of each channel is observed by an image sensor with randomly arranged optical elements for filtering. The object data are reconstructed using a compressive sensing algorithm. This scheme is verified with numerical experiments. The proposed framework can be applied to imageries for spectrum, polarization, and so on.

  7. Building an open-source simulation platform of acoustic radiation force-based breast elastography

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Peng, Bo; Jiang, Jingfeng

    2017-03-01

    Ultrasound-based elastography including strain elastography, acoustic radiation force impulse (ARFI) imaging, point shear wave elastography and supersonic shear imaging (SSI) have been used to differentiate breast tumors among other clinical applications. The objective of this study is to extend a previously published virtual simulation platform built for ultrasound quasi-static breast elastography toward acoustic radiation force-based breast elastography. Consequently, the extended virtual breast elastography simulation platform can be used to validate image pixels with known underlying soft tissue properties (i.e. ‘ground truth’) in complex, heterogeneous media, enhancing confidence in elastographic image interpretations. The proposed virtual breast elastography system inherited four key components from the previously published virtual simulation platform: an ultrasound simulator (Field II), a mesh generator (Tetgen), a finite element solver (FEBio) and a visualization and data processing package (VTK). Using a simple message passing mechanism, functionalities have now been extended to acoustic radiation force-based elastography simulations. Examples involving three different numerical breast models with increasing complexity—one uniform model, one simple inclusion model and one virtual complex breast model derived from magnetic resonance imaging data, were used to demonstrate capabilities of this extended virtual platform. Overall, simulation results were compared with the published results. In the uniform model, the estimated shear wave speed (SWS) values were within 4% compared to the predetermined SWS values. In the simple inclusion and the complex breast models, SWS values of all hard inclusions in soft backgrounds were slightly underestimated, similar to what has been reported. The elastic contrast values and visual observation show that ARFI images have higher spatial resolution, while SSI images can provide higher inclusion-to-background contrast

  8. Building an open-source simulation platform of acoustic radiation force-based breast elastography.

    PubMed

    Wang, Yu; Peng, Bo; Jiang, Jingfeng

    2017-03-07

    Ultrasound-based elastography including strain elastography, acoustic radiation force impulse (ARFI) imaging, point shear wave elastography and supersonic shear imaging (SSI) have been used to differentiate breast tumors among other clinical applications. The objective of this study is to extend a previously published virtual simulation platform built for ultrasound quasi-static breast elastography toward acoustic radiation force-based breast elastography. Consequently, the extended virtual breast elastography simulation platform can be used to validate image pixels with known underlying soft tissue properties (i.e. 'ground truth') in complex, heterogeneous media, enhancing confidence in elastographic image interpretations. The proposed virtual breast elastography system inherited four key components from the previously published virtual simulation platform: an ultrasound simulator (Field II), a mesh generator (Tetgen), a finite element solver (FEBio) and a visualization and data processing package (VTK). Using a simple message passing mechanism, functionalities have now been extended to acoustic radiation force-based elastography simulations. Examples involving three different numerical breast models with increasing complexity-one uniform model, one simple inclusion model and one virtual complex breast model derived from magnetic resonance imaging data, were used to demonstrate capabilities of this extended virtual platform. Overall, simulation results were compared with the published results. In the uniform model, the estimated shear wave speed (SWS) values were within 4% compared to the predetermined SWS values. In the simple inclusion and the complex breast models, SWS values of all hard inclusions in soft backgrounds were slightly underestimated, similar to what has been reported. The elastic contrast values and visual observation show that ARFI images have higher spatial resolution, while SSI images can provide higher inclusion-to-background contrast. In

  9. Acoustic wave velocities in two-dimensional composite structures based on acousto-optical crystals

    NASA Astrophysics Data System (ADS)

    Mal'neva, P. V.; Trushin, A. S.

    2015-04-01

    Sound velocities in two-dimensional composite structures based on isotropic and anisotropic acousto-optical crystals have been determined by numerical simulations. The isotropic materials are represented by fused quartz (SiO2) and flint glass, while anisotropic materials include tetragonal crystals of paratellurite (TeO2) and rutile (TiO2) and a trigonal crystal of tellurium (Te). It is established that the acoustic anisotropy of periodic composite structures strongly depends on both the chemical composition and geometric parameters of components.

  10. In situ high-temperature characterization of AlN-based surface acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Aubert, Thierry; Bardong, Jochen; Legrani, Ouarda; Elmazria, Omar; Badreddine Assouar, M.; Bruckner, Gudrun; Talbi, Abdelkrim

    2013-07-01

    We report on in situ electrical measurements of surface acoustic wave delay lines based on AlN/sapphire structure and iridium interdigital transducers between 20 °C and 1050 °C under vacuum conditions. The devices show a great potential for temperature sensing applications. Burnout is only observed after 60 h at 1050 °C and is mainly attributed to the agglomeration phenomena undergone by the Ir transducers. However, despite the vacuum conditions, a significant oxidation of the AlN film is observed, pointing out the limitation of the considered structure at least at such extreme temperatures. Original structures overcoming this limitation are then proposed and discussed.

  11. Combined failure acoustical diagnosis based on improved frequency domain blind deconvolution

    NASA Astrophysics Data System (ADS)

    Pan, Nan; Wu, Xing; Chi, YiLin; Liu, Xiaoqin; Liu, Chang

    2012-05-01

    According to gear box combined failure extraction in complex sound field, an acoustic fault detection method based on improved frequency domain blind deconvolution was proposed. Follow the frequency-domain blind deconvolution flow, the morphological filtering was firstly used to extract modulation features embedded in the observed signals, then the CFPA algorithm was employed to do complex-domain blind separation, finally the J-Divergence of spectrum was employed as distance measure to resolve the permutation. Experiments using real machine sound signals was carried out. The result demonstrate this algorithm can be efficiently applied to gear box combined failure detection in practice.

  12. Compressive sensing beamforming based on covariance for acoustic imaging with noisy measurements.

    PubMed

    Zhong, Siyang; Wei, Qingkai; Huang, Xun

    2013-11-01

    Compressive sensing, a newly emerging method from information technology, is applied to array beamforming and associated acoustic applications. A compressive sensing beamforming method (CSB-II) is developed based on sampling covariance matrix, assuming spatially sparse and incoherent signals, and then examined using both simulations and aeroacoustic measurements. The simulation results clearly show that the proposed CSB-II method is robust to sensing noise. In addition, aeroacoustic tests of a landing gear model demonstrate the good performance in terms of resolution and sidelobe rejection.

  13. Generalized phase-shifting digital holography for single-exposure

    NASA Astrophysics Data System (ADS)

    Nomura, Takanori; Imbe, Masatoshi

    2015-07-01

    Single exposure phase-shifting digital holography is mandatory for recording/analyzing dynamic phenomena. As one of the candidate for the single exposure phase-shifting digital holography is the wave-splitting phase-shifting digital holography. We have proposed generalized phase-shifting digital holography as one of the wave-splitting phase-shifting digital holography. In the digital holography, the phase-shift quantity, which corresponds to the difference between the phase quantities of the reference wave on the adjacent pixels is generalized different from ordinal wave-splitting methods. Owing to the generalized phase-shifting, we can use a random-phase wave as the reference wave. The proposed phase-shifting digital holography enables us to record a fully-complex field of a dynamic phenomena without dc and conjugate terms using a commercially available optical devices. The relation between the property of the reference wave and the quality of the reconstructed images are discussed. Experimental results are given to confirm the proposed phase-shifting digital holography.

  14. Display holography in the United Kingdom, 1994-1997

    NASA Astrophysics Data System (ADS)

    Benyon, Margaret

    1998-02-01

    This paper reports on developments in display holography in the UK since 1994, covering the activities of individual holographers and artists, small companies and larger commercial concerns. It also includes comments on reactions to the withdrawal of Agfa-Geveart Ltd from the production of silver-halide materials for holography.

  15. Image quality improvement of polygon computer generated holography.

    PubMed

    Pang, Xiao-Ning; Chen, Ding-Chen; Ding, Yi-Cong; Chen, Yi-Gui; Jiang, Shao-Ji; Dong, Jian-Wen

    2015-07-27

    Quality of holographic reconstruction image is seriously affected by undesirable messy fringes in polygon-based computer generated holography. Here, several methods have been proposed to improve the image quality, including a modified encoding method based on spatial-domain Fraunhofer diffraction and a specific LED light source. Fast Fourier transform is applied to the basic element of polygon and fringe-invisible reconstruction is achieved after introducing initial random phase. Furthermore, we find that the image with satisfactory fidelity and sharp edge can be reconstructed by either a LED with moderate coherence level or a modulator with small pixel pitch. Satisfactory image quality without obvious speckle noise is observed under the illumination of bandpass-filter-aided LED. The experimental results are consistent well with the correlation analysis on the acceptable viewing angle and the coherence length of the light source.

  16. Focus detection criterion for refocusing in multi-wavelength digital holography.

    PubMed

    Xu, Li; Mater, Mike; Ni, Jun

    2011-08-01

    The majority of focus detection criteria reported is based on amplitude contrast. Due to phase wrapping, phase contrast was previously reported unsuitable for focus finding tasks. By taking the advantage of multi-wavelength digital holography, we propose a new focus detection criterion based on phase contrast. Experimental results are presented to prove the feasibility of the developed criterion. Possible applications of the developed technology include inspecting machined surfaces in the auto industry.

  17. Acoustic emission based monitoring of the microdamage evolution during fatigue of human cortical bone.

    PubMed

    Agcaoglu, Serife; Akkus, Ozan

    2013-08-01

    Stress fractures are frequently observed in physically active populations, and they are believed to be associated with microcrack accumulation. There are not many tools for real-time monitoring of microdamage formation during fatigue of bone, in vivo or in vitro. Acoustic emission (AE) based detection of stress waves resulting from microdamage formation is a promising method to assess the rate and energetics of microdamage formation during fatigue. The current study aims to assess the time history of the occurrence of AE events during fatigue loading of human tibial cortical bone and to determine the associations between AE variables (energy content of waves, number of AE waveforms, etc.), fatigue life, and bone ash content. Fatigue test specimens were prepared from the distal diaphysis of human tibial cortical bone (N = 32, 22 to 52 years old, male and female). The initiation of acoustic emissions was concomitant with the nonlinear increase in sample compliance and the cumulative number of AE events increased asymptotically in the prefailure period. The results demonstrated that AE method was able to predict the onset of failure by 95% of the fatigue life for the majority of the samples. The variation in the number of emissions until failure ranged from 6 to 1861 implying a large variation in crack activity between different samples. The results also revealed that microdamage evolution was a function of the level of tissue mineralization such that more mineralized bone matrix failed with fewer crack events with higher energy whereas less mineralized tissue generated more emissions with lower energy. In conclusion, acoustic emission based surveillance during fatigue of cortical bone demonstrates a large scatter, where some bones fail with substantial crack activity and a minority of samples fail without significant amount of crack formation.

  18. The Characterization of Surface Acoustic Wave Devices Based on AlN-Metal Structures

    PubMed Central

    Shu, Lin; Peng, Bin; Li, Chuan; Gong, Dongdong; Yang, Zhengbing; Liu, Xingzhao; Zhang, Wanli

    2016-01-01

    We report in this paper on the study of surface acoustic wave (SAW) resonators based on an AlN/titanium alloy (TC4) structure. The AlN/TC4 structure with different thicknesses of AlN films was simulated, and the acoustic propagating modes were discussed. Based on the simulation results, interdigital transducers with a periodic length of 24 μm were patterned by lift-off photolithography techniques on the AlN films/TC4 structure, while the AlN film thickness was in the range 1.5–3.5 μm. The device performances in terms of quality factor (Q-factor) and electromechanical coupling coefficient (k2) were determined from the measure S11 parameters. The Q-factor and k2 were strongly dependent not only on the normalized AlN film thickness but also on the full-width at half-maximum (FWHM) of AlN (002) peak. The dispersion curve of the SAW phase velocity was analyzed, and the experimental results showed a good agreement with simulations. The temperature behaviors of the devices were also presented and discussed. The prepared SAW resonators based on AlN/TC4 structure have potential applications in integrated micromechanical sensing systems. PMID:27077864

  19. The design of Helmholtz resonator based acoustic lenses by using the symmetric Multi-Level Wave Based Method and genetic algorithms

    NASA Astrophysics Data System (ADS)

    Atak, Onur; Huybrechs, Daan; Pluymers, Bert; Desmet, Wim

    2014-07-01

    Sonic crystals can be used as acoustic lenses in certain frequencies and the design of such systems by creating vacancies and using genetic algorithms has been proven to be an effective method. So far, rigid cylinders have been used to create such acoustic lens designs. On the other hand, it has been proven that Helmholtz resonators can be used to construct acoustic lenses with higher refraction index as compared to rigid cylinders, especially in low frequencies by utilizing their local resonances. In this paper, these two concepts are combined to design acoustic lenses that are based on Helmholtz resonators. The Multi-Level Wave Based Method is used as the prediction method. The benefits of the method in the context of design procedure are demonstrated. In addition, symmetric boundary conditions are derived for more efficient calculations. The acoustic lens designs that use Helmholtz resonators are compared with the acoustic lens designs that use rigid cylinders. It is shown that using Helmholtz resonator based sonic crystals leads to better acoustic lens designs, especially at the low frequencies where the local resonances are pronounced.

  20. Phage-based magnetostrictive-acoustic microbiosensors for detecting bacillus anthracis spores

    NASA Astrophysics Data System (ADS)

    Wan, J.; Yang, H.; Lakshmanan, R. S.; Guntupalli, R.; Huang, S.; Hu, J.; Petrenko, V. A.; Chin, B. A.

    2006-05-01

    Magnetostrictive particles (MSPs) as biosensor platform have been developed recently. The principle of MSPs as sensor platform is the same as that of other acoustic wave devices, such as quartz crystal microbalance. In this paper, the fabrication, characterization and performance of phage-based MSP biosensors for detecting Bacillus anthracis spores are reported. A commercially available magnetostrictive alloy was utilized to fabricate the sensor platform. The phage was immobilized onto the MSPs using physical adsorption technology. The following performance of the phage-based MSP sensors will be presented: sensitivity, response time, longevity, specificity and binding efficacy. The performance of the sensors at static and dynamic conditions was characterized. The experimental results are confirmed by microscopy photographs. The excellent performance including high sensitivity and rapid response is demonstrated. More importantly, it is experimentally found that the phage-based MSP sensors have a much better longevity than antibody-based sensors.

  1. Demodulation of acoustic telemetry binary phase shift keying signal based on high-order Duffing system

    NASA Astrophysics Data System (ADS)

    Yan, Bing-Nan; Liu, Chong-Xin; Ni, Jun-Kang; Zhao, Liang

    2016-10-01

    In order to grasp the downhole situation immediately, logging while drilling (LWD) technology is adopted. One of the LWD technologies, called acoustic telemetry, can be successfully applied to modern drilling. It is critical for acoustic telemetry technology that the signal is successfully transmitted to the ground. In this paper, binary phase shift keying (BPSK) is used to modulate carrier waves for the transmission and a new BPSK demodulation scheme based on Duffing chaos is investigated. Firstly, a high-order system is given in order to enhance the signal detection capability and it is realized through building a virtual circuit using an electronic workbench (EWB). Secondly, a new BPSK demodulation scheme is proposed based on the intermittent chaos phenomena of the new Duffing system. Finally, a system variable crossing zero-point equidistance method is proposed to obtain the phase difference between the system and the BPSK signal. Then it is determined that the digital signal transmitted from the bottom of the well is ‘0’ or ‘1’. The simulation results show that the demodulation method is feasible. Project supported by the National Natural Science Foundation of China (Grant No. 51177117) and the National Key Science & Technology Special Projects, China (Grant No. 2011ZX05021-005).

  2. Lightweight filter architecture for energy efficient mobile vehicle localization based on a distributed acoustic sensor network.

    PubMed

    Kim, Keonwook

    2013-08-23

    The generic properties of an acoustic signal provide numerous benefits for localization by applying energy-based methods over a deployed wireless sensor network (WSN). However, the signal generated by a stationary target utilizes a significant amount of bandwidth and power in the system without providing further position information. For vehicle localization, this paper proposes a novel proximity velocity vector estimator (PVVE) node architecture in order to capture the energy from a moving vehicle and reject the signal from motionless automobiles around the WSN node. A cascade structure between analog envelope detector and digital exponential smoothing filter presents the velocity vector-sensitive output with low analog circuit and digital computation complexity. The optimal parameters in the exponential smoothing filter are obtained by analytical and mathematical methods for maximum variation over the vehicle speed. For stationary targets, the derived simulation based on the acoustic field parameters demonstrates that the system significantly reduces the communication requirements with low complexity and can be expected to extend the operation time considerably.

  3. Trends in acoustic neuroma management: a 20-year review of the oxford skull base clinic.

    PubMed

    Mackeith, Samuel A C; Kerr, Richard S; Milford, Chris A

    2013-08-01

    Objective To describe the change in the management of acoustic neuromas at one United Kingdom center over a 20-year period and to compare this with what is known regarding trends in practice on a national and international scale. Design, Setting, and Participants Data was collected prospectively on all patients attending the Oxford Skull Base Clinic between 1990 and 2009. Main Outcome Measures The proportion of patients managed initially by observation versus radiotherapy versus surgery was recorded for each year. Results Significantly more patients received radiation treatment (instead of surgery) between 2000 and 2009 when compared with 1990 to 1999. Compared with national audit data, the Oxford Skull Base Clinic treats a higher proportion of patients with radiotherapy and significantly lower proportion with surgery, though the trend nationally is toward more observation and radiotherapy and less surgery. Conclusion Surgery will remain crucial in the management of some patients with acoustic neuromas (usually those with the larger tumors where radiosurgery is recognized to be less appropriate), but using current trends to predict future practice would suggest that alternative nonmicrosurgical treatment may play an increasingly important role in the future.

  4. Acoustic emission-based condition monitoring methods: Review and application for low speed slew bearing

    NASA Astrophysics Data System (ADS)

    Caesarendra, Wahyu; Kosasih, Buyung; Tieu, Anh Kiet; Zhu, Hongtao; Moodie, Craig A. S.; Zhu, Qiang

    2016-05-01

    This paper presents an acoustic emission-based method for the condition monitoring of low speed reversible slew bearings. Several acoustic emission (AE) hit parameters as the monitoring parameters for the detection of impending failure of slew bearings are reviewed first. The review focuses on: (1) the application of AE in typical rolling element bearings running at different speed classifications, i.e. high speed (>600 rpm), low speed (10-600 rpm) and very low speed (<10 rpm); (2) the commonly used AE hit parameters in rolling element bearings and (3) AE signal processing, feature extraction and pattern recognition methods. In the experiment, impending failure of the slew bearing was detected by the AE hit parameters after the new bearing had run continuously for approximately 15 months. The slew bearing was then dismantled and the evidence of the early defect was analysed. Based on the result, we propose a feature extraction method of the AE waveform signal using the largest Lyapunov exponent (LLE) algorithm and demonstrate that the LLE feature can detect the sign of failure earlier than the AE hit parameters with improved prediction of the progressive trend of the defect.

  5. Speech timing and linguistic rhythm: on the acoustic bases of rhythm typologies.

    PubMed

    Rathcke, Tamara V; Smith, Rachel H

    2015-05-01

    Research into linguistic rhythm has been dominated by the idea that languages can be classified according to rhythmic templates, amenable to assessment by acoustic measures of vowel and consonant durations. This study tested predictions of two proposals explaining the bases of rhythmic typologies: the Rhythm Class Hypothesis which assumes that the templates arise from an extensive vs a limited use of durational contrasts, and the Control and Compensation Hypothesis which proposes that the templates are rooted in more vs less flexible speech production strategies. Temporal properties of segments, syllables and rhythmic feet were examined in two accents of British English, a "stress-timed" variety from Leeds, and a "syllable-timed" variety spoken by Panjabi-English bilinguals from Bradford. Rhythm metrics were calculated. A perception study confirmed that the speakers of the two varieties differed in their perceived rhythm. The results revealed that both typologies were informative in that to a certain degree, they predicted temporal patterns of the two varieties. None of the metrics tested was capable of adequately reflecting the temporal complexity found in the durational data. These findings contribute to the critical evaluation of the explanatory adequacy of rhythm metrics. Acoustic bases and limitations of the traditional rhythmic typologies are discussed.

  6. Deep Recurrent Neural Network-Based Autoencoders for Acoustic Novelty Detection

    PubMed Central

    Vesperini, Fabio; Schuller, Björn

    2017-01-01

    In the emerging field of acoustic novelty detection, most research efforts are devoted to probabilistic approaches such as mixture models or state-space models. Only recent studies introduced (pseudo-)generative models for acoustic novelty detection with recurrent neural networks in the form of an autoencoder. In these approaches, auditory spectral features of the next short term frame are predicted from the previous frames by means of Long-Short Term Memory recurrent denoising autoencoders. The reconstruction error between the input and the output of the autoencoder is used as activation signal to detect novel events. There is no evidence of studies focused on comparing previous efforts to automatically recognize novel events from audio signals and giving a broad and in depth evaluation of recurrent neural network-based autoencoders. The present contribution aims to consistently evaluate our recent novel approaches to fill this white spot in the literature and provide insight by extensive evaluations carried out on three databases: A3Novelty, PASCAL CHiME, and PROMETHEUS. Besides providing an extensive analysis of novel and state-of-the-art methods, the article shows how RNN-based autoencoders outperform statistical approaches up to an absolute improvement of 16.4% average F-measure over the three databases. PMID:28182121

  7. Lightweight Filter Architecture for Energy Efficient Mobile Vehicle Localization Based on a Distributed Acoustic Sensor Network

    PubMed Central

    Kim, Keonwook

    2013-01-01

    The generic properties of an acoustic signal provide numerous benefits for localization by applying energy-based methods over a deployed wireless sensor network (WSN). However, the signal generated by a stationary target utilizes a significant amount of bandwidth and power in the system without providing further position information. For vehicle localization, this paper proposes a novel proximity velocity vector estimator (PVVE) node architecture in order to capture the energy from a moving vehicle and reject the signal from motionless automobiles around the WSN node. A cascade structure between analog envelope detector and digital exponential smoothing filter presents the velocity vector-sensitive output with low analog circuit and digital computation complexity. The optimal parameters in the exponential smoothing filter are obtained by analytical and mathematical methods for maximum variation over the vehicle speed. For stationary targets, the derived simulation based on the acoustic field parameters demonstrates that the system significantly reduces the communication requirements with low complexity and can be expected to extend the operation time considerably. PMID:23979482

  8. Transcranial ultrasonic therapy based on time reversal of acoustically induced cavitation bubble signature

    PubMed Central

    Gâteau, Jérôme; Marsac, Laurent; Pernot, Mathieu; Aubry, Jean-Francois; Tanter, Mickaël; Fink, Mathias

    2010-01-01

    Brain treatment through the skull with High Intensity Focused Ultrasound (HIFU) can be achieved with multichannel arrays and adaptive focusing techniques such as time-reversal. This method requires a reference signal to be either emitted by a real source embedded in brain tissues or computed from a virtual source, using the acoustic properties of the skull derived from CT images. This non-invasive computational method focuses with precision, but suffers from modeling and repositioning errors that reduce the accessible acoustic pressure at the focus in comparison with fully experimental time-reversal using an implanted hydrophone. In this paper, this simulation-based targeting has been used experimentally as a first step for focusing through an ex vivo human skull at a single location. It has enabled the creation of a cavitation bubble at focus that spontaneously emitted an ultrasonic wave received by the array. This active source signal has allowed 97%±1.1% of the reference pressure (hydrophone-based) to be restored at the geometrical focus. To target points around the focus with an optimal pressure level, conventional electronic steering from the initial focus has been combined with bubble generation. Thanks to step by step bubble generation, the electronic steering capabilities of the array through the skull were improved. PMID:19770084

  9. Searching for Traces of Martian Life Using Holography

    NASA Astrophysics Data System (ADS)

    Ksanfomality, Leonid; Kompanets, Igor

    A sample of the Martian regolith to be delivered in future missions to Mars may provide an important information on traces of the extinct life when studied in the laboratory. Of course, there will be only few samples (by technical reasons) and their structure will inevitably be distorted by the extracting mechanisms. There is an another possibility, looking for a morphology sign affected by life, using a special TV camera, too. However it is very difficult to return an information of this kind of the TV, mainly due to the enormous amount of the information to be returned. The proposal made in this paper is to use a holography technics collecting many shots of undistorted objects on the surface of Mars using a special photosensitive film, and to return the film together with a soil sample. The mass of the film roll is neglectable when compared with a package of a soil sample. The holograph experiment results are a lot more informative then the stereo (two points of view), having the number points of view = object solid angle / solid angle resolution. The object may be examined from many sides. A resolution of such a film may be up to 5000 lines/mm, that is much, much higher than any TV image. The instrument proposed for the project is based on the most advanced new investigations in the holography, that permits to minimize (4 to 6 fold) the mass, sizes an power assumption of the camera. The goal of the project is to investigate micro morphology of the Martian surface features (stones, sand, dust). The Camera Specification (preliminary) Mass & Less than 4 kg Sizes (mm) & 300 times 100 times 150 Power assumption & averaged < 1W, pulse up to 100W. Lazer & YAG (Nd), 2nd harmonic Wavelength & 530 nm Structure & Fiber optics Photo film & High resolution (up to 5000 mm^{-1}) Object maximum size (mm)& 100 Frame size (mm) & 100 times 250 Number of shots & 12-20 In some sense all things, now widely used in space research, were risky innovations in the past. A holograph in

  10. THz holography in reflection using a high resolution microbolometer array.

    PubMed

    Zolliker, Peter; Hack, Erwin

    2015-05-04

    We demonstrate a digital holographic setup for Terahertz imaging of surfaces in reflection. The set-up is based on a high-power continuous wave (CW) THz laser and a high-resolution (640 × 480 pixel) bolometer detector array. Wave propagation to non-parallel planes is used to reconstruct the object surface that is rotated relative to the detector plane. In addition we implement synthetic aperture methods for resolution enhancement and compare Fourier transform phase retrieval to phase stepping methods. A lateral resolution of 200 μm and a relative phase sensitivity of about 0.4 rad corresponding to a depth resolution of 6 μm are estimated from reconstructed images of two specially prepared test targets, respectively. We highlight the use of digital THz holography for surface profilometry as well as its potential for video-rate imaging.

  11. Terahertz digital holography image denoising using stationary wavelet transform

    NASA Astrophysics Data System (ADS)

    Cui, Shan-Shan; Li, Qi; Chen, Guanghao

    2015-04-01

    Terahertz (THz) holography is a frontier technology in terahertz imaging field. However, reconstructed images of holograms are inherently affected by speckle noise, on account of the coherent nature of light scattering. Stationary wavelet transform (SWT) is an effective tool in speckle noise removal. In this paper, two algorithms for despeckling SAR images are implemented to THz images based on SWT, which are threshold estimation and smoothing operation respectively. Denoised images are then quantitatively assessed by speckle index. Experimental results show that the stationary wavelet transform has superior denoising performance and image detail preservation to discrete wavelet transform. In terms of the threshold estimation, high levels of decomposing are needed for better denoising result. The smoothing operation combined with stationary wavelet transform manifests the optimal denoising effect at single decomposition level, with 5×5 average filtering.

  12. Miniaturized digital holography sensor for distal three-dimensional endoscopy.

    PubMed

    Kolenovic, Ervin; Osten, Wolfgang; Klattenhoff, Reiner; Lai, Songcan; von Kopylow, Christoph; Jüptner, Werner

    2003-09-01

    A miniaturized sensor head for endoscopic measurements based on digital holography is described. The system was developed to measure the shape and the three-dimensional deformation of objects located at places to which there is no access by common measurement systems. A miniaturized optical sensor, including a complete digital holographic interferometer with a CCD camera, is placed at the end of a flexible endoscope. The diameter of the head is smaller than 10 mm. The system enables interferometric measurements to be made at speeds of as many as five reconstructions per second, and it can be used outside the laboratory under normal environmental conditions. Shape measurements are performed with two wavelengths for contouring, and the deformation is measured by digital holographic interferometry. To obtain full three-dimensional data in displacement measurements we illuminate the object sequentially from three different illumination directions. To increase the lateral resolution we use temporal phase shifting.

  13. Time-average TV holography for vibration fringe analysis

    SciTech Connect

    Kumar, Upputuri Paul; Kalyani, Yanam; Mohan, Nandigana Krishna; Kothiyal, Mahendra Prasad

    2009-06-01

    Time-average TV holography is widely used method for vibration measurement. The method generates speckle correlation time-averaged J0 fringes that can be used for full-field qualitative visualization of mode shapes at resonant frequencies of an object under harmonic excitation. In order to map the amplitudes of vibration, quantitative evaluation of the time-averaged fringe pattern is desired. A quantitative evaluation procedure based on the phase-shifting technique used in two beam interferometry has also been adopted for this application with some modification. The existing procedure requires a large number of frames to be recorded for implementation. We propose a procedure that will reduce the number of frames required for the analysis. The TV holographic system used and the experimental results obtained with it on an edge-clamped, sinusoidally excited square aluminium plate sample are discussed.

  14. Surface-Plasmon Holography with White-Light Illumination

    NASA Astrophysics Data System (ADS)

    Ozaki, Miyu; Kato, Jun-ichi; Kawata, Satoshi

    2011-04-01

    The recently emerging three-dimensional (3D) displays in the electronic shops imitate depth illusion by overlapping two parallax 2D images through either polarized glasses that viewers are required to wear or lenticular lenses fixed directly on the display. Holography, on the other hand, provides real 3D imaging, although usually limiting colors to monochrome. The so-called rainbow holograms—mounted, for example, on credit cards—are also produced from parallax images that change color with viewing angle. We report on a holographic technique based on surface plasmons that can reconstruct true 3D color images, where the colors are reconstructed by satisfying resonance conditions of surface plasmon polaritons for individual wavelengths. Such real 3D color images can be viewed from any angle, just like the original object.

  15. Surface-plasmon holography with white-light illumination.

    PubMed

    Ozaki, Miyu; Kato, Jun-ichi; Kawata, Satoshi

    2011-04-08

    The recently emerging three-dimensional (3D) displays in the electronic shops imitate depth illusion by overlapping two parallax 2D images through either polarized glasses that viewers are required to wear or lenticular lenses fixed directly on the display. Holography, on the other hand, provides real 3D imaging, although usually limiting colors to monochrome. The so-called rainbow holograms--mounted, for example, on credit cards--are also produced from parallax images that change color with viewing angle. We report on a holographic technique based on surface plasmons that can reconstruct true 3D color images, where the colors are reconstructed by satisfying resonance conditions of surface plasmon polaritons for individual wavelengths. Such real 3D color images can be viewed from any angle, just like the original object.

  16. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study.

    PubMed

    Jones, Ryan M; O'Reilly, Meaghan A; Hynynen, Kullervo

    2013-07-21

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337-43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source's emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system's resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring techniques currently exist.

  17. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study

    PubMed Central

    Jones, Ryan M.; O’Reilly, Meaghan A.; Hynynen, Kullervo

    2013-01-01

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337–43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source’s emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system’s resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring technique currently exists. PMID:23807573

  18. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study

    NASA Astrophysics Data System (ADS)

    Jones, Ryan M.; O'Reilly, Meaghan A.; Hynynen, Kullervo

    2013-07-01

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337-43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source’s emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system’s resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring techniques currently exist.

  19. Improving the performance of acoustic invisibility with multilayer structure based on scattering analysis

    NASA Astrophysics Data System (ADS)

    Cai, Chen; Yuan, Yin; Kan, Wei-Wei; Yang, Jing; Zou, Xin-Ye

    2016-12-01

    In this paper, acoustic scattering from the system comprised of a cloaked object and the multilayer cloak with only one single pair of isotropic media is analyzed with a recursive numerical method. The designed acoustic parameters of the isotropic cloak media are assumed to be single-negative, and the resulting cloak can reduce acoustic scattering from an acoustic sensor while allowing it to receive external information. Several factors that may influence the performance of the cloak, including the number of layers and the acoustic dissipation of the medium are fully analyzed. Furthermore, the possibility of achieving acoustic invisibility with positive acoustic parameters is proposed by searching the optimum value in the parameter space and minimizing the scattering cross-section. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274168, 11374157, 11174138, 11174139, 11222442, and 81127901) and the National Basic Research Program of China (Grant Nos. 2010CB327803 and 2012CB921504).

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  1. 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

    2014-11-24

    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.

  2. Phase shifting digital holography implemented with a twisted-nematic liquid-crystal display.

    PubMed

    Cruz, Maria-Luisa; Castro, Albertina; Arrizón, Victor

    2009-12-20

    We describe and experimentally demonstrate a phase shifting method based on the lateral displacement of a grating implemented with a twisted-nematic liquid-crystal spatial light modulator. This method allows an accurate implementation of the phase shift without requiring moving parts. The technique is implemented in a Mach-Zehnder digital holography setup in which the field transmitted by the sample object freely propagates to the hologram plane.

  3. Magnetic imaging by Fourier transform holography using linearly polarized x-rays.

    PubMed

    Sacchi, Maurizio; Popescu, Horia; Jaouen, Nicolas; Tortarolo, Marina; Fortuna, Franck; Delaunay, Renaud; Spezzani, Carlo

    2012-04-23

    We present a method for imaging magnetic domains via x-ray Fourier transform holography at linearly polarized sources. Our approach is based on the separation of holographic mask and sample and on the Faraday rotation induced on the reference wave. We compare images of perpendicular magnetic domains obtained with either linearly or circularly polarized x-rays and discuss the relevance of this method to future experiments at free-electron laser and high-harmonic-generation sources.

  4. The room acoustic rendering equation.

    PubMed

    Siltanen, Samuel; Lokki, Tapio; Kiminki, Sami; Savioja, Lauri

    2007-09-01

    An integral equation generalizing a variety of known geometrical room acoustics modeling algorithms is presented. The formulation of the room acoustic rendering equation is adopted from computer graphics. Based on the room acoustic rendering equation, an acoustic radiance transfer method, which can handle both diffuse and nondiffuse reflections, is derived. In a case study, the method is used to predict several acoustic parameters of a room model. The results are compared to measured data of the actual room and to the results given by other acoustics prediction software. It is concluded that the method can predict most acoustic parameters reliably and provides results as accurate as current commercial room acoustic prediction software. Although the presented acoustic radiance transfer method relies on geometrical acoustics, it can be extended to model diffraction and transmission through materials in future.

  5. Acoustic Neuroma

    MedlinePlus

    ... search IRSA's site Unique Hits since January 2003 Acoustic Neuroma Click Here for Acoustic Neuroma Practice Guideline ... to microsurgery. One doctor's story of having an acoustic neuroma In August 1991, Dr. Thomas F. Morgan ...

  6. Ion-acoustic Shocks with Reflected Ions: Implications for laser-based proton accelerators

    NASA Astrophysics Data System (ADS)

    Sagdeev, Roald; Malkov, Mikhail; Dudnikova, Galina; Liseykina, Tatyana; Diamond, Patrick; Liu, C.-S.; Su, J.-J.

    2014-10-01

    Analytic solution for an ion-acoustic collisionless shock with reflected ions is obtained. Its relation to classical non-reflecting solitons propagating at Mach numbers strictly limited by M acoustic shock itself formed in place of the soliton. The shock reflected ions progressively fill up an extended foot region ending with the second transition that propagates faster than the rear shock but slower than the most of reflected ions. A small fraction of these ions still remains trapped in the transition to maintain charge neutrality. Most of them pass through this front transition, and accelerate whereas their distribution becomes noteworthily monoenergetic. The obtained solution may thus have interesting implications for the laser-based ion accelerators. Applications to particle acceleration in geophysical and astrophysical shocks are discussed. Partially supported by NASA, ATP NNX14AH36G, and the US DoE.

  7. A structure state evaluation method based on electric-thermo-acoustic effect for tension materials

    NASA Astrophysics Data System (ADS)

    Yin, Aijun; Zhang, Panpan; Ouyang, Qi

    2016-10-01

    The material properties of a structure will change over the course of its service life. Monitoring for material properties can be used to evaluate equipment state. Characterising and tracking variations in properties have promising potential for the detection and evaluation of material state caused by fatigue or residual stress. Theoretical analysis for the formation of a thermo-acoustic effect is carried out and it reveals a kind of interaction between the resonance of gas heat and that of solid heat. This paper introduces an electric-thermo-acoustic model with a multi-layered structure and analyses the effects of the material properties on sound pressure. Based on this effect, a method for evaluating the performance of a multi-layered structure material is proposed that can be used to assess a greater number of physical properties than the existing approaches. The simulations and experiments with variations in material property are generated and processed with the proposed model, and the results verify the method’s efficiency.

  8. [A comparative study of pathological voice based on traditional acoustic characteristics and nonlinear features].

    PubMed

    Gan, Deying; Hu, Weiping; Zhao, Bingxin

    2014-10-01

    By analyzing the mechanism of pronunciation, traditional acoustic parameters, including fundamental frequency, Mel frequency cepstral coefficients (MFCC), linear prediction cepstrum coefficient (LPCC), frequency perturbation, amplitude perturbation, and nonlinear characteristic parameters, including entropy (sample entropy, fuzzy entropy, multi-scale entropy), box-counting dimension, intercept and Hurst, are extracted as feature vectors for identification of pathological voice. Seventy-eight normal voice samples and 73 pathological voice samples for /a/, and 78 normal samples and 80 pathological samples for /i/ are recognized based on support vector machine (SVM). The results showed that compared with traditional acoustic parameters, nonlinear characteristic parameters could be well used to distinguish between healthy and pathological voices, and the recognition rates for /a/ were all higher than those for /i/ except for multi-scale entropy. That is why the /a/ sound data is used widely in related research at home and abroad for obtaining better identification of pathological voices. Adopting multi-scale entropy for /i/ could obtain higher recognition rate than /a/ between healthy and pathological samples, which may provide some useful inspiration for evaluating vocal compensatory function.

  9. A Device for Fetal Monitoring by Means of Control Over Cardiovascular Parameters Based on Acoustic Data

    NASA Astrophysics Data System (ADS)

    Khokhlova, L. A.; Seleznev, A. I.; Zhdanov, D. S.; Zemlyakov, I. Yu; Kiseleva, E. Yu

    2016-01-01

    The problem of monitoring fetal health is topical at the moment taking into account a reduction in the level of fertile-age women's health and changes in the concept of perinatal medicine with reconsideration of live birth criteria. Fetal heart rate monitoring is a valuable means of assessing fetal health during pregnancy. The routine clinical measurements are usually carried out by the means of ultrasound cardiotocography. Although the cardiotocography monitoring provides valuable information on the fetal health status, the high quality ultrasound devices are expensive, they are not available for home care use. The recommended number of measurement is also limited. The passive and fully non-invasive acoustic recording provides an alternative low-cost measurement method. The article describes a device for fetal and maternal health monitoring by analyzing the frequency and periodicity of heart beats by means of acoustic signal received on the maternal abdomen. Based on the usage of this device a phonocardiographic fetal telemedicine system, which will allow to reduce the antenatal fetal mortality rate significantly due to continuous monitoring over the state of fetus regardless of mother's location, can be built.

  10. Nondeterministic wave-based methods for low- and mid-frequency response analysis of acoustic field with limited information

    NASA Astrophysics Data System (ADS)

    Xia, Baizhan; Yin, Hui; Yu, Dejie

    2017-02-01

    The response of the acoustic field, especially for the mid-frequency response, is very sensitive to uncertainties rising from manufacturing/construction tolerances, aggressive environmental factors and unpredictable excitations. To quantify these uncertainties with limited information effectively, two nondeterministic models (the interval model and the hybrid probability-interval model) are introduced. And then, two corresponding nondeterministic numerical methods are developed for the low- and mid-frequency response analysis of the acoustic field under these two nondeterministic models. The first one is the interval perturbation wave-based method (IPWBM) which is proposed to predict the maximal values of the low- and mid-frequency responses of the acoustic field under the interval model. The second one is the hybrid perturbation wave-based method (HPWBM) which is proposed to predict the maximal values of expectations and standard variances of the low- and mid-frequency responses of the acoustic field under the hybrid probability-interval model. The effectiveness and efficiency of the proposed nondeterministic numerical methods for the low- and mid-frequency response analysis of the acoustic field under the interval model and the hybrid probability-interval model are investigated by a numerical example.

  11. Ethereal presences in holography and photography

    NASA Astrophysics Data System (ADS)

    Richardson, M.; Byrne, Kay

    2007-02-01

    This paper examines the concept of the 'Presence of Absence' in post-mortem photography and holography, drawing upon both historical and lesser-known images as reference. To create a photographic negative one needs the presence of light to expose the light sensitive surface, be it glass, a polished plate or plastic. A hologram may also be created when a coherent light source, for example from a Laser, travels through a light sensitive material and falls upon the subject to be recorded. A holograph however, retains the optical qualities of both phase and amplitude, the memory of light. Both mediums recall, as it were, 'now absent moments', and confronts us with what is 'not there' as much as 'what is'. This paper examines the exploration of absence and presence in post-mortem photography and holography and it's a richly visceral visual language. A photonic syntax can interpret death as an elegant yet horrific aesthetic, the photograph may be beautify screened and yet obscene in its content. In essence one can be a voyeur, experiencing a mere visual whisper of the true nature of the subject. Our Victorian forefathers explored postmortem photography as an object of mourning, and at the close of the nineteenth century when Jack the Ripper had the inhabitants of White Chapel in a grip of fear, photography made its mark as a documentation of violent crime. Today, within contemporary photography, death is now presented within the confines of the 'Art Gallery', as a sensual, and at times, sensationalised art form. In exploring post-mortem imagery, both in holography and conventional photography, absence presents an aspect of death as startling in its unanimated form and detailed in its finite examination of mortality.

  12. General band gap condition in one-dimensional resonator-based acoustic metamaterial

    NASA Astrophysics Data System (ADS)

    Liu, Yafei; Hou, Zhilin; Fu, Xiujun

    2016-03-01

    A one-dimensional model for resonator-based acoustic metamaterials is introduced. The condition for band gap in such kind of structure is obtained. According to this condition, the dispersion relation is in general a result of the scattering phase and propagating phase. The phenomenon that the band gap is less dependent on lattice structure appears only in the special system in which the coupling between the resonators and the host medium is weak enough. For strong coupled systems, the dispersion of wave can be significantly adjusted by the propagating phase. Based on the understanding, a general guide for band gap optimization is given and the mechanism for structures with the defect states at subwavelength scale is revealed.

  13. Modeling of systems wireless data transmission based on antenna arrays in underwater acoustic channels

    NASA Astrophysics Data System (ADS)

    Fedosov, V. P.; Lomakina, A. V.; Legin, A. A.; Voronin, V. V.

    2016-05-01

    In this paper the system of wireless transmission of data based on the use an adaptive algorithm for processing spatial-time signals using antenna arrays is presented. In the transmission of data in a multipath propagation of signals have been used such technologies as a MIMO (Multiple input-Multiple output) and OFDM (Orthogonal frequency division multiplexing) to solve the problem of increasing the maximum speed of data transfer and the low probability of errors. The adaptation process is based on the formation of the directional pattern equivalent to the amplitude antenna array in the signal arrival direction with the highest capacity on one of propagation paths in the channel. The simulation results showed that the use of an adaptive algorithm on the reception side can significantly reduce the probability of bit errors, thus to increase throughput in an underwater acoustic data channel.

  14. Acoustic emission localization based on FBG sensing network and SVR algorithm

    NASA Astrophysics Data System (ADS)

    Sai, Yaozhang; Zhao, Xiuxia; Hou, Dianli; Jiang, Mingshun

    2016-11-01

    In practical application, carbon fiber reinforced plastics (CFRP) structures are easy to appear all sorts of invisible damages. So the damages should be timely located and detected for the safety of CFPR structures. In this paper, an acoustic emission (AE) localization system based on fiber Bragg grating (FBG) sensing network and support vector regression (SVR) is proposed for damage localization. AE signals, which are caused by damage, are acquired by high speed FBG interrogation. According to the Shannon wavelet transform, time differences between AE signals are extracted for localization algorithm based on SVR. According to the SVR model, the coordinate of AE source can be accurately predicted without wave velocity. The FBG system and localization algorithm are verified on a 500 mm×500 mm×2 mm CFRP plate. The experimental results show that the average error of localization system is 2.8 mm and the training time is 0.07 s.

  15. Acoustic emission localization based on FBG sensing network and SVR algorithm

    NASA Astrophysics Data System (ADS)

    Sai, Yaozhang; Zhao, Xiuxia; Hou, Dianli; Jiang, Mingshun

    2017-03-01

    In practical application, carbon fiber reinforced plastics (CFRP) structures are easy to appear all sorts of invisible damages. So the damages should be timely located and detected for the safety of CFPR structures. In this paper, an acoustic emission (AE) localization system based on fiber Bragg grating (FBG) sensing network and support vector regression (SVR) is proposed for damage localization. AE signals, which are caused by damage, are acquired by high speed FBG interrogation. According to the Shannon wavelet transform, time differences between AE signals are extracted for localization algorithm based on SVR. According to the SVR model, the coordinate of AE source can be accurately predicted without wave velocity. The FBG system and localization algorithm are verified on a 500 mm×500 mm×2 mm CFRP plate. The experimental results show that the average error of localization system is 2.8 mm and the training time is 0.07 s.

  16. Solder joint failure localization of welded joint based on acoustic emission beamforming.

    PubMed

    Liu, Xiandong; Xiao, Denghong; Shan, Yingchun; Pan, Qiang; He, Tian; Gao, Yong

    2017-02-01

    A localization approach of welded joint damage is proposed based on acoustic emission (AE) beamforming. In this method, a uniform line array is introduced to detect the AE signal of welded joints in specified area. In order to investigate the influence of fillet and crimping commonly existing in a welded plate structure during the AE wave propagation process, the finite element method (FEM) is applied to simulate the behavior of AE wave in the specimen. The simulation localization results indicate that the proposed localization approach can effectively localize AE sources although there exist the fillet and crimping, and it is also validated by the pencil-lead-broken test on rectangular steel tube with welded joints. Finally, the proposed method is adopted to localize the failure of solder joint in operation vibration condition. The proposed method is successful to localize the compact AE source caused by the cracked joint based on wavelet packet transform.

  17. Surgical removal of giant acoustic neurinomas involving the skull base. Report of two cases.

    PubMed

    Sawamura, Y; Nakagawa, Y; Ikota, T; Abe, H

    1989-10-01

    Neurinomas arising from the peripheral branch of the acoustic nerve distal to the internal auditory canal in the temporal bone are rare. Two advanced skull-base neurinomas are described which were situated mainly in the temporal petrous bone, and extended to the parapharyngeal space anteriorly, to the lateral cervical portion inferiorly, into the sphenoidal sinus medially, and into the middle and posterior cranial fossae compressing the brain stem. Both patients had been deaf for several years without other neurological deficits. The operative findings revealed that the fifth, seventh, and caudal cranial nerves were intact; therefore, it was suspected that these neurinomas originated primarily within the cochlea or the vestibule in the temporal bone. The tumors were completely removed via an extradural approach, with good results. Since the surgical treatment of such advanced skull-base neurinomas is difficult, the operative infratemporal fossa approach is described in detail.

  18. Applications of digital holography to measurements and optical characterization

    NASA Astrophysics Data System (ADS)

    Sang, Xinzhu; Yu, Chongxiu; Yu, Miao; Hsu, Dashsiung

    2011-09-01

    With recent advances in high-speed computer and video capture technology, holographic films used in classical holography can be replaced with charged-coupled devices (CCD) and complementary metal-oxide-semiconductor (CMOS) image sensors to record and numerically reconstruct a hologram, which is now known as digital holography. Digital holography introduces something new to optical science. Wet chemical processing and other time-consuming procedures can be removed, so numerical recording and reconstruction can be realized in almost real time. It allows us to characterize the phase of a light field as well the intensity, and so the whole wave field can be measured and stored in a computer. Digital holography is expanding applications of holography and becoming a scientific and technological tool. Its use has now increased for measuring amplitude and the phase of object waves, displacement and three dimensional shape, particle distributions and motions, characterization of the refractive index and biological tissues, and vibration analysis, etc. Here, basic principles of digital holography for optical measurement and characterization are described. Taking into consideration the rapid advance in CCD and CMOS sensors as the background, the state-of-the-art applications of digital holography to optical measurement and characterization are presented.

  19. Compressive holography reconstruction using phase-shifting interferometry

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng; Shen, Chuan; Cheng, Hong; Zhang, Fen; Liu, Kaifeng; Zhang, Quanbing; Wei, Sui

    2015-05-01

    In classical compressive holography (CH), which based on the Gabor holography setup, two nonlinear terms are inherent in the intensity recorded by a 2D detector arrays, the DC term and the squared field term. The DC term (the term at the origin) can be eliminated by filtering the Fourier transform of the interference irradiance measurements using appropriate high-pass filter near the zero frequency. The nonlinearity caused by the squared field term can be neglected and modeled as a error term in the measurement. However, the above assumptions are significantly limited, which yields the degradation of reconstruction quality. In this paper, an novel scheme using phase-shifting method is presented. To accurately recover the complex optical field caused by the propagation of the object, without the influence of the DC term and the squared field term, a very effective method for removing these two terms is introduced. The complex optical field of the 3D object and the complex optical field at the detector plane can be precisely represented by a linear mapping model. The complex optical field at the recorder plane is obtained by phase-shifting interferometry with multiple shots. Then, the corresponded complex optical field at the detector plane can be successfully extracted from multiple captured holograms using conventional four phase-shifting interferometry. From such complex optical field at the record plane, including the amplitude and phase information, the complex optical field of the 3D object can be reconstructed via an optimization procedure. Numerical results demonstrate the effectiveness of our proposed method.

  20. Functional holography analysis: Simplifying the complexity of dynamical networks

    NASA Astrophysics Data System (ADS)

    Baruchi, Itay; Grossman, Danny; Volman, Vladislav; Shein, Mark; Hunter, John; Towle, Vernon L.; Ben-Jacob, Eshel

    2006-03-01

    We present a novel functional holography (FH) analysis devised to study the dynamics of task-performing dynamical networks. The latter term refers to networks composed of dynamical systems or elements, like gene networks or neural networks. The new approach is based on the realization that task-performing networks follow some underlying principles that are reflected in their activity. Therefore, the analysis is designed to decipher the existence of simple causal motives that are expected to be embedded in the observed complex activity of the networks under study. First we evaluate the matrix of similarities (correlations) between the activities of the network's components. We then perform collective normalization of the similarities (or affinity transformation) to construct a matrix of functional correlations. Using dimension reduction algorithms on the affinity matrix, the matrix is projected onto a principal three-dimensional space of the leading eigenvectors computed by the algorithm. To retrieve back information that is lost in the dimension reduction, we connect the nodes by colored lines that represent the level of the similarities to construct a holographic network in the principal space. Next we calculate the activity propagation in the network (temporal ordering) using different methods like temporal center of mass and cross correlations. The causal information is superimposed on the holographic network by coloring the nodes locations according to the temporal ordering of their activities. First, we illustrate the analysis for simple, artificially constructed examples. Then we demonstrate that by applying the FH analysis to modeled and real neural networks as well as recorded brain activity, hidden causal manifolds with simple yet characteristic geometrical and topological features are deciphered in the complex activity. The term "functional holography" is used to indicate that the goal of the analysis is to extract the maximum amount of functional

  1. A novel method for identifying the order of interference using phase-shifting digital holography.

    PubMed

    Sokkar, T Z N; El-Farahaty, K A; Ramadan, W A; Wahba, H H; Raslan, M I; Hamza, A A

    2016-04-01

    In this paper, we introduced a mathematical method for measuring the optical path length differences (OPDs), which is suitable for large OPD values where the fringes connections are difficult to detect. The proposed method is based on varying the width of the fringes, without changing the wavelength of the used coherent source. Also, in this work, we discussed the need for such method in off-axis phase-shifting digital holography. Low-resolution off-axis holograms failed to detect the correct interference order. In general, off-axis phase-shifting digital holography is limited by the resolution of the captured holograms. The results obtained using our proposed technique were compared to the results obtained using off-axis phase-shifting digital holograms and conventional two-beam interferometry. Holograms were given for illustration.

  2. Statistical generalized phase-shifting digital holography with a continuous fringe-scanning scheme.

    PubMed

    Yoshikawa, Nobukazu; Kajihara, Kazuki

    2015-07-01

    We propose a novel statistical generalized phase-shifting digital holography using a continuous fringe-scanning scheme. In this method, the continuous fringe-scanning scheme is implemented using a PC-based measurement system without any synchronous circuit between the digital camera and the phase shifter. Thus, nonuniformly phase-shifted interference fringes are captured sequentially because of the fluctuation of the image-capturing interval. To cope with the nonuniform phase shifts, we employ a statistical generalized phase-shifting approach. Since the algorithm is designed to use an arbitrary phase shift, the nonuniform phase shifts do not obstruct object wave retrieval. Simulations and experiments demonstrate that the proposed method can be used to implement a practical and accurate digital holography system.

  3. Free-viewpoint images captured using phase-shifting synthetic aperture digital holography.

    PubMed

    Nakatsuji, Tatsuya; Matsushima, Kyoji

    2008-07-01

    Free-viewpoint images obtained from phase-shifting synthetic aperture digital holography are given for scenes that include multiple objects and a concave object. The synthetic aperture technique is used to enlarge the effective sensor size and to make it possible to widen the range of changing perspective in the numerical reconstruction. The lensless Fourier setup and its aliasing-free zone are used to avoid aliasing errors arising at the sensor edge and to overcome a common problem in digital holography, namely, a narrow field of view. A change of viewpoint is realized by a double numerical propagation and by clipping the wave field by a given pupil. The computational complexity for calculating an image in the given perspective from the base complex-valued image is estimated at a double fast Fourier transform. The experimental results illustrate the natural change of appearance in cases of both multiple objects and a concave object.

  4. "Kunstwerk" in the age of holography

    NASA Astrophysics Data System (ADS)

    Öhlmann, Dietmar; Meulien Ohlmann, Odile

    2013-02-01

    In 2007 one auction shocked collectors and artists: Two art works of Rudie Berkhout were offered for one thousand dollars on eBay. The closing down of museums for holography in Cologne, New York and Washington DC paid a big price of respect for true art. Benjamin's vision about "Art in the Age of Mechanical Reproduction" found a new expression in abuse and ignorance. Beautiful sculptures of Art are reduced to "Holograms" like Rudie's "Cairo Aspect" placed in a rummage sale, covered by fingerprints of ignorance.

  5. Observation of magnetic multilayers by electron holography.

    PubMed

    Tanji, T; Hasebe, S; Nakagami, Y; Yamamoto, K; Ichihashi, M

    2004-02-01

    Magnetic structures of Co/Cu multilayers in cross section are observed by two kinds of electron holography: a Fourier method and a phase-shifting method, which is introduced briefly. The Fourier method can easily reconstruct wave functions and is applied to many specimens, whereas the phase-shifting method requires longer time for processing, but has a higher spatial resolution that permits us to discuss fine structures. Magnetization vectors in Co layers aligning parallel and separating into two blocks with antiparallel alignment are observed. Magnetic blurring on the boundary between Co and Cu in the reconstructed phase images is larger than the estimated atomic roughness.

  6. Optical vortex phase-shifting digital holography.

    PubMed

    Guo, Cheng-Shan; Cheng, Xin; Ren, Xiu-Yun; Ding, Jian-Ping; Wang, Hui-Tian

    2004-10-18

    We report a new optical vortex phase-shifting method for digital holography, in which an optical vortex mode is taken as the reference beam for holographic recording, and the required phase shifts are directly generated by rotating the vortex mode. In digital reconstruction, the complex amplitude of the object wave can be retrieved by use of the conventional phase shifting algorithm on condition that the digital illumination beam is replaced by an vortex beam with the same topological charge as the reference used. Both the theoretical analysis and experimental results demonstrate the feasibility of this approach.

  7. Infrared digital holography for large objects investigation

    NASA Astrophysics Data System (ADS)

    Geltrude, A.; Locatelli, M.; Poggi, P.; Pelagotti, A.; Paturzo, M.; Ferraro, P.; Meucci, R.

    2011-05-01

    In this work we show several acquisition setups and techniques which make it possible to obtain holographic recording and reconstruction of large objects by means of Infrared Digital Holography (IDH). In previous works it was demonstrated that, using the long wavelength coherent radiation produced by a CO2 laser instead of visible radiation, it is possible to obtain advantages in terms of larger field of view and lower seismic noise sensitivity. The only drawback using this wavelength is represented by the low resolution of current recording devices in this spectral region. The reported methods may have industrial applications where investigation of large dimension samples is needed.

  8. Improved processing for silver halide pulse holography

    NASA Astrophysics Data System (ADS)

    Mikhailov, Viktor N.; Son, Jung-Young; Grinevitskaya, Olga V.; Lee, Hyuk-Soo; Choi, Yong-Jin

    1996-04-01

    Using of an improved developer with optical latensification allowed to significantly increase exposure sensitivity of currently in use silver halide materials. Transmission large-scale holograms (30 X 40 cm2) of diffused objects have been recorded under pulse exposure of about 6.5 X 10-6 J/cm2 for VRP and of about 2 X 10-6 J/cm2 for Agfa-Gavaert 8E56HD, in both cases without appreciable contrast deterioration. Results of the first experiments on pulse reflection holography are also discussed.

  9. Multi-field inflation from holography

    SciTech Connect

    Garriga, Jaume; Urakawa, Yuko; Skenderis, Kostas E-mail: K.Skenderis@soton.ac.uk

    2015-01-01

    We initiate the study of multi-field inflation using holography. Bulk light scalar fields correspond to nearly marginal operators in the boundary theory and the dual quantum field theory is a deformation of a CFT by such operators. We compute the power spectra of adiabatic and entropy perturbations in a simple model and find that the adiabatic curvature perturbation is not conserved in the presence of entropy perturbations but becomes conserved when the entropy perturbations are set to zero or the model is effectively a single scalar model, in agreement with expectations from cosmological perturbation theory.

  10. A system of enlarging visual field and viewing zone simultaneously for electro-holography

    NASA Astrophysics Data System (ADS)

    Nagai, Toshiaki; Yabe, Yoshiaki; Sakamoto, Yuji

    2007-02-01

    It is difficult to realize a practical electro-holography, because visual field and viewing zone are limited, which are very narrow to see by both eyes. The problems are caused by the resolution of devices that display fringe pattern, such as on a SLM (spatial light modulator) and an AOM (acoustic optic modulator). A low resolution of device occurs ghost images that are high-order diffraction images of reconstructed images. Therefore the ghost images prevent large visual field and large viewing zone. We propose new configuration of electro-holography using LCD (liquid crystal display) that enlarges visual field and viewing zone simultaneously. The system consists of an array of reconstruction lights, LCD, electro-shutter that is located between SLM and viewer. It is possible to prevent the rays from the ghost images by the shutter, to choose appropriate positions of both a reconstruction light in array and an aperture of electro-shutter. It shows viewers the original 3D objects without ghosts. Switching the combination of positions of reconstruction light and aperture of shutter for all fringe patterns synchronously is possible to see no-ghost images from any point of view. Furthermore, to switching very fast by time-division multiplexing, we can get large visual field and large viewing zone simultaneously. To verify the principle of the method, we made a system and carried out the experiments. In this paper, we discuss the method and the experimental results.

  11. Quantifying activation of perfluorocarbon-based phase-change contrast agents using simultaneous acoustic and optical observation.

    PubMed

    Li, Sinan; Lin, Shengtao; Cheng, Yi; Matsunaga, Terry O; Eckersley, Robert J; Tang, Meng-Xing

    2015-05-01

    Phase-change contrast agents in the form of nanoscale droplets can be activated into microbubbles by ultrasound, extending the contrast beyond the vasculature. This article describes simultaneous optical and acoustical measurements for quantifying the ultrasound activation of phase-change contrast agents over a range of concentrations. In experiments, decafluorobutane-based nanodroplets of different dilutions were sonicated with a high-pressure activation pulse and two low-pressure interrogation pulses immediately before and after the activation pulse. The differences between the pre- and post-interrogation signals were calculated to quantify the acoustic power scattered by the microbubbles activated over a range of droplet concentrations. Optical observation occurred simultaneously with the acoustic measurement, and the pre- and post-microscopy images were processed to generate an independent quantitative indicator of the activated microbubble concentration. Both optical and acoustic measurements revealed linear relationships to the droplet concentration at a low concentration range <10(8)/mL when measured at body temperature. Further increases in droplet concentration resulted in saturation of the acoustic interrogation signal. Compared with body temperature, room temperature was found to produce much fewer and larger bubbles after ultrasound droplet activation.

  12. Acoustic method for defining the stress state of a rock massif based on solution of the seismic inverse problem

    NASA Astrophysics Data System (ADS)

    Nazarov, L. A.; Nazarova, L. A.; Romenskii, E. I.; Tcheverda, V. A.; Epov, M. I.

    2016-02-01

    A method for estimating the stress-strain state of a rock massif in the vicinity of underground facilities is substantiated. This method is based on solution of the boundary inverse problem of defining the components of an external stress field from the acoustic sounding data. The acoustic sounding data used are the arrival times of diving head longitudinal waves, recorded in a long mine shaft. Numerical experiments have revealed the optimal arrangement of the recording network and the limited relative error in the input data, which, taken together, provide for solvability of the inverse problem.

  13. Ultra-directional source of longitudinal acoustic waves based on a two-dimensional solid/solid phononic crystal

    SciTech Connect

    Morvan, B.; Tinel, A.; Sainidou, R.; Rembert, P.; Vasseur, J. O.; Hladky-Hennion, A.-C.; Swinteck, N.; Deymier, P. A.

    2014-12-07

    Phononic crystals (PC) can be used to control the dispersion properties of acoustic waves, which are essential to direct their propagation. We use a PC-based two-dimensional solid/solid composite to demonstrate experimentally and theoretically the spatial filtering of a monochromatic non-directional wave source and its emission in a surrounding water medium as an ultra-directional beam with narrow angular distribution. The phenomenon relies on square-shaped equifrequency contours (EFC) enabling self-collimation of acoustic waves within the phononic crystal. Additionally, the angular width of collimated beams is controlled via the EFC size-shrinking when increasing frequency.

  14. Measurement of Bubble Size Distribution Based on Acoustic Propagation in Bubbly Medium

    NASA Astrophysics Data System (ADS)

    Wu, Xiongjun; Hsiao, Chao-Tsung; Choi, Jin-Keun; Chahine, Georges

    2013-03-01

    Acoustic properties are strongly affected by bubble size distribution in a bubbly medium. Measurement of the acoustic transmission becomes increasingly difficulty as the void fraction of the bubbly medium increases due to strong attenuation, while acoustic reflection can be measured more easily with increasing void fraction. The ABS ACOUSTIC BUBBLE SPECTROMETER®\\copyright, an instrument for bubble size measurement that is under development tries to take full advantage of the properties of acoustic propagation in bubbly media to extract bubble size distribution. Properties of both acoustic transmission and reflection in the bubbly medium from a range of short single-frequency bursts of acoustic waves at different frequencies are measured in an effort to deduce the bubble size distribution. With the combination of both acoustic transmission and reflection, assisted with validations from photography, the ABS ACOUSTIC BUBBLE SPECTROMETER®\\copyright has the potential to measure bubble size distributions in a wider void fraction range. This work was sponsored by Department of Energy SBIR program

  15. A Longitudinal Mode Electromagnetic Acoustic Transducer (EMAT) Based on a Permanent Magnet Chain for Pipe Inspection

    PubMed Central

    Cong, Ming; Wu, Xinjun; Qian, Chunqiao

    2016-01-01

    A new electromagnetic acoustic transducer (EMAT) design, employing a special structure of the permanent magnet chain, is proposed to generate and receive longitudinal guided waves for pipe inspection based on the magnetostriction mechanism. Firstly, a quantitative analysis of the excitation forces shows the influence of the radial component can be ignored. Furthermore, as the axial component of the static magnetic field is dominant, a method of solenoid testing coils connected in series is adopted to increase the signal amplitude. Then, two EMAT configurations are developed to generate and receive the L(0,2) guided wave mode. The experimental results show the circumferential notch can be identified and located successfully. Finally, a detailed investigation of the performance of the proposed EMATs is given. Compared to the conventional EMAT configuration, the proposed configurations have the advantages of small volume, light weight, easy installation and portability, which is helpful to improve inspection efficiency. PMID:27213400

  16. Parametric amplification of orbital angular momentum beams based on light-acoustic interaction

    SciTech Connect

    Gao, Wei E-mail: zhuzhihandd@sina.com; Mu, Chunyuan; Yang, Yuqiang; Li, Hongwei; Zhu, Zhihan E-mail: zhuzhihandd@sina.com

    2015-07-27

    A high fidelity amplification of beams carrying orbital angular momentum (OAM) is very crucial for OAM multiplexing and other OAM-based applications. Here, we report a demonstration of stimulated Brillouin amplification for OAM beams, and the energy conversion efficiency of photon-phonon coupling and the phase structure of amplified signals are investigated in collinear and noncollinear frame systems, respectively. Our results demonstrate that the OAM signals can be efficiently amplified without obvious noise introduced, and the modes of output signal are independent of the pump modes or the geometrical frames. Meanwhile, an OAM state depending on the optical modes and the geometrical frames is loaded into phonons by coherent light-acoustic interaction, which reveals more fundamental significance and a great application potential in OAM-multiplexing.

  17. High-frequency surface acoustic wave device based on thin-film piezoelectric interdigital transducers

    SciTech Connect

    Sarin Kumar, A.K.; Paruch, P.; Triscone, J.-M.; Daniau, W.; Ballandras, S.; Pellegrino, L.; Marre, D.; Tybell, T.

    2004-09-06

    Using high-quality epitaxial c-axis Pb(Zr{sub 0.2}Ti{sub 0.8})O{sub 3} films grown by off-axis magnetron sputtering onto metallic (001) Nb-doped SrTiO{sub 3} substrates, a nonconventional thin-film surface acoustic wave device based on periodic piezoelectric transducers was realized. The piezoelectric transducers consist of a series of ferroelectric domains with alternating polarization states. The artificial modification of the ferroelectric domain structure is performed by using an atomic force microscope tip as a source of electric field, allowing local switching of the polarization. Devices with 1.2 and 0.8 {mu}m wavelength, defined by the modulation period of the polarization, and corresponding to central frequencies in the range 1.50-3.50 GHz have been realized and tested.

  18. Acoustic planar hyperlens based on anisotropic density-near-zero metamaterials

    SciTech Connect

    Gu, Yuan; Cheng, Ying Liu, Xiaojun

    2015-09-28

    Based on anisotropic density-near-zero metamaterials, we demonstrate a planar hyperlens with resolution beyond the diffraction limit in both one and two lateral dimensions. In contrast to the cylindrical hyperlens with elliptical dispersions of finite anisotropy, the proposed planar hyperlens is designed with flat near-zero dispersion that supports wave tunneling with extremely high phase velocity for infinite large transverse wave vectors. Therefore, the acoustic evanescent waves immediately concentrate into the designed oblique path till the output surface, leading to a subwavelength resolution. Prototype hyperlens is constructed with a membrane-network by means of equivalent lumped-circuit model, and the subwavelength magnifying performance for a pair of one-dimensional line objects as well as the complex two-dimensional structure is demonstrated. This method provides diverse routes to construct hyperlens operating without the limitation on imaging region in practical applications.

  19. Multiple concurrent sources localization based on a two-node distributed acoustic sensor network

    NASA Astrophysics Data System (ADS)

    Xu, Jiaxin; Zhao, Zhao; Chen, Chunzeng; Xu, Zhiyong

    2017-01-01

    In this work, we propose a new approach to localize multiple concurrent sources using a distributed acoustic sensor network. Only two node-arrays are required in this sensor network, and each node-array consists of only two widely spaced sensors. Firstly, direction-of-arrivals (DOAs) of multiple sources are estimated at each node-array by utilizing a new pooled angular spectrum proposed in this paper, which can implement the spatial aliasing suppression effectively. Based on minimum variance distortionless response (MVDR) beamforming and the DOA estimates of the sources, the time-frequency spectra containing the corresponding energy distribution features associated with those sources are reconstructed in each node-array. Then, scale invariant feature transform (SIFT) is employed to solve the DOA association problem. Performance evaluation is conducted with field recordings and experimental results prove the effectivity and feasibility of the proposed method.

  20. A Network Coding Based Hybrid ARQ Protocol for Underwater Acoustic Sensor Networks

    PubMed Central

    Wang, Hao; Wang, Shilian; Zhang, Eryang; Zou, Jianbin

    2016-01-01

    Underwater Acoustic Sensor Networks (UASNs) have attracted increasing interest in recent years due to their extensive commercial and military applications. However, the harsh underwater channel causes many challenges for the design of reliable underwater data transport protocol. In this paper, we propose an energy efficient data transport protocol based on network coding and hybrid automatic repeat request (NCHARQ) to ensure reliability, efficiency and availability in UASNs. Moreover, an adaptive window length estimation algorithm is designed to optimize the throughput and energy consumption tradeoff. The algorithm can adaptively change the code rate and can be insensitive to the environment change. Extensive simulations and analysis show that NCHARQ significantly reduces energy consumption with short end-to-end delay. PMID:27618044

  1. Ground based studies of the vibrational and rotational dynamics of acoustically levitated drops and shells

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Leung, E.

    1990-01-01

    A substantial amount of experimental data can be gathered on the dynamics of acoustically positioned liquids in a ground-based laboratory and during short duration low-gravity parabolic flights of the KC-135. The preliminary results of a set of measurements of the static shape, of the vibrational spectrum, and the rotation equilibrium shapes of simple drops and liquid shells carried out using ultrasonic levitators working between 19 and 40 kHz is presented. The droplet diameter ranges between 1 and 5 mm, the surface tension of the liquid used varies between 25 and 70 dynes/cm, and the viscosity is changed between 1 to 1,000 cP. Of particular interest is the variation of the frequency of the fundamental mode of shape oscillation with various factors, and the effects of static drop shape deformation on the limit of stability of the axisymmetric shape of a drop in solid-body rotation.

  2. Phase-based dispersion analysis for acoustic array borehole logging data.

    PubMed

    Assous, Said; Elkington, Peter; Linnett, Laurie

    2014-04-01

    A phase-based dispersion analysis method for velocity (slowness) extraction from guided waves recorded by an acoustic borehole logging tool in a geological formation is presented. The technique consists of acquiring waveforms from an array of receivers distributed along the tool and constructing the dispersion characteristic by processing in the frequency domain and exploiting phase information to measure the travel time for each frequency component. The approach is nonparametric and completely data-driven and provides high resolution estimates that do not rely on velocity guesses or assumptions regarding the type of modes. Results are free of the aliases and spurious modes which are characteristic of some prior approaches. Examples of dispersion estimation curves are presented using synthesized flexural waves and field data from wireline dipole sonic tools; results are compared with those from the weighted spectral semblance (WSS) and amplitude and phase slowness estimation (APES) methods to demonstrate the effectiveness and utility of the proposed method.

  3. High-resolution imaging using endoscopic holography

    NASA Astrophysics Data System (ADS)

    Bjelkhagen, Hans I.

    1990-08-01

    Endoscopic holography or endoholography combines the features of endoscopy and holography. The purpose of endoholographic imaging is to provide the physician with a unique means of extending diagnosis by providing a life-like record of tissue. Endoholographic recording will provide means for microscopic examination of tissue and in some cases may obviate the need to excise specimens for biopsy. In this method holograms which have the unique properties of three-dimensionality large focal depth and high resolution are made with a newly designed endoscope. The endoscope uses a single-mode optical fiber for illumination and single-beam reflection holograms are recorded in close contact with the tissue at the distal end of the endoscope. The holograms are viewed under a microscope. By using the proper combinations of dyes for staining specific tissue types with various wavelengths of laser illumination increased contrast on the cellular level can be obtained. Using dyes such as rose bengal in combination with the 514. 5 nm line of an argon ion laser and trypan blue or methylene blue with the 647. 1 nm line of a krypton ion laser holograms of the stained colon of a dog showed the architecture of the colon''s columnar epithelial cells. It is hoped through chronological study using this method in-vivo an increased understanding of the etiology and pathology of diseases such as Crohn''s diseases colitis proctitis and several different forms of cancer will help to their control. 1.

  4. Stückelberg formulation of holography

    NASA Astrophysics Data System (ADS)

    Dvali, Gia; Gomez, Cesar; Wintergerst, Nico

    2016-10-01

    We suggest that holography can be formulated in terms of the information capacity of the Stückelberg degrees of freedom that maintain gauge invariance of the theory in the presence of an information boundary. These Stückelbergs act as qubits that account for a certain fraction of quantum information. Their information capacity is measured by the ratio of the inverse Stückelberg energy gap to the size of the system. Systems with the smallest gap are maximally holographic. For massless gauge systems this information measure is universally equal to the inverse coupling evaluated at the systems' length scale. In this language it becomes very transparent why the Stückelberg information capacity of black holes saturates the Bekenstein bound and accounts for the entire information of the system. The physical reason is that the strength of quantum interaction is bounded from below by the gravitational coupling, which scales as area. Observing the striking similarity between the scalings of the energy gap of the boundary Stückelberg modes and the Bogoliubov modes of critical many-body systems, we establish a connection between holography and quantum criticality through the correspondence between these modes.

  5. Massively parallel X-ray holography

    SciTech Connect

    Spence, John C.H; Marchesini, Stefano; Boutet, Sebastien; Sakdinawat, Anne E.; Bogan, Michael J.; Bajt, Sasa; Barty, Anton; Chapman, Henry N.; Frank, Matthias; Hau-Riege, Stefan P.; Szöke, Abraham; Cui, Congwu; Shapiro, David A.; Howells, MAlcolm R.; Shaevitz, Joshua W; Lee, Joanna Y.; Hajdu, Janos; Seibert, Marvin M.

    2008-08-01

    Advances in the development of free-electron lasers offer the realistic prospect of nanoscale imaging on the timescale of atomic motions. We identify X-ray Fourier-transform holography1,2,3 as a promising but, so far, inefficient scheme to do this. We show that a uniformly redundant array4 placed next to the sample, multiplies the efficiency of X-ray Fourier transform holography by more than three orders of magnitude, approaching that of a perfect lens, and provides holographic images with both amplitude- and phase-contrast information. The experiments reported here demonstrate this concept by imaging a nano-fabricated object at a synchrotron source, and a bacterial cell with a soft-X-ray free-electron laser, where illumination by a single 15-fs pulse was successfully used in producing the holographic image. As X-ray lasers move to shorter wavelengths we expect to obtain higher spatial resolution ultrafast movies of transient states of matter

  6. Introductory overview of holography and speckle

    NASA Astrophysics Data System (ADS)

    Parker, David E.

    1990-10-01

    The purpose of this paper is to provide a nonmathematical overview of holographic and speckle interferometry. This provides information necessary for those participants with little or no background in these areas to understand the application papers in the Holography Speckle session of ICALEO''89. Holography A hologram is an optical device which is capable of producing threedimensional images. The word hologram stems from the Greek root holos which means whole complete or entire and the word gram which means message. Thus a hologram is a complete record of a scene or object. The first hologram was produced by Dennis Gabor in 1948. In 1971 he won the Nobel Prize for his work. Leith and Upatnieks produced the first holograms using a laser in the early 1960''s. In conventional photography the light reflected from a scene is focused by a camera lens onto a photographic emulsion. The variation in irradiance of the light reaching the emulsion is related only to the amplitude of the electric field due to the light. To produce three-dimensional images a hologram records information about both the amplitude and phase of light reflected from a scene or object. Production Hologram Figure 1 is a sketch of a system which can be used to produce optical holograms. A laser operating in the TEM mode is used as a light source. A continuous wave or a pulsed laser can be

  7. Compressed digital holography: from micro towards macro

    NASA Astrophysics Data System (ADS)

    Schretter, Colas; Bettens, Stijn; Blinder, David; Pesquet-Popescu, Béatrice; Cagnazzo, Marco; Dufaux, Frédéric; Schelkens, Peter

    2016-09-01

    signal processing methods from software-driven computer engineering and applied mathematics. The compressed sensing theory in particular established a practical framework for reconstructing the scene content using few linear combinations of complex measurements and a sparse prior for regularizing the solution. Compressed sensing found direct applications in digital holography for microscopy. Indeed, the wave propagation phenomenon in free space mixes in a natural way the spatial distribution of point sources from the 3-dimensional scene. As the 3-dimensional scene is mapped to a 2-dimensional hologram, the hologram samples form a compressed representation of the scene as well. This overview paper discusses contributions in the field of compressed digital holography at the micro scale. Then, an outreach on future extensions towards the real-size macro scale is discussed. Thanks to advances in sensor technologies, increasing computing power and the recent improvements in sparse digital signal processing, holographic modalities are on the verge of practical high-quality visualization at a macroscopic scale where much higher resolution holograms must be acquired and processed on the computer.

  8. Simulated electron holography of PSD particles

    NASA Astrophysics Data System (ADS)

    Conbhuí, Pádraig Ó.; Williams, Wyn; Nagy, Les

    2016-04-01

    Electron holography is an experimental technique that is capable of observing magnetic microstructures on the same scale as can be determined using numerical modeling and thus bridge the gap between experimental measurements and theory. I will present a technique for simulating holographic images from the results of micromagnetic models and demonstrate an easily used tool for generating holograms on the fly in an interactive environment (ie in ParaView). Since holography flattens 3D information onto a 2D image, some useful information can be lost. By looking at some examples of holograms of interesting 3D magnetizations (ie PSD structures), particularly how they change as they're rotated, along with comparisons of different structures, I will examine what information can be retrieved and what might be lost. The existance of an external dipole can be indicative of an in-plane component of a seemingly out-of-plane vortex core. It is also seen, however, that two quite different structures (in this case a [111] vortex core and a [111] uniform magnetization) can sometimes be quite indistinguishable.

  9. Discrimination of speech stimuli based on neuronal response phase patterns depends on acoustics but not comprehension.

    PubMed

    Howard, Mary F; Poeppel, David

    2010-11-01

    Speech stimuli give rise to neural activity in the listener that can be observed as waveforms using magnetoencephalography. Although waveforms vary greatly from trial to trial due to activity unrelated to the stimulus, it has been demonstrated that spoken sentences can be discriminated based on theta-band (3-7 Hz) phase patterns in single-trial response waveforms. Furthermore, manipulations of the speech signal envelope and fine structure that reduced intelligibility were found to produce correlated reductions in discrimination performance, suggesting a relationship between theta-band phase patterns and speech comprehension. This study investigates the nature of this relationship, hypothesizing that theta-band phase patterns primarily reflect cortical processing of low-frequency (<40 Hz) modulations present in the acoustic signal and required for intelligibility, rather than processing exclusively related to comprehension (e.g., lexical, syntactic, semantic). Using stimuli that are quite similar to normal spoken sentences in terms of low-frequency modulation characteristics but are unintelligible (i.e., their time-inverted counterparts), we find that discrimination performance based on theta-band phase patterns is equal for both types of stimuli. Consistent with earlier findings, we also observe that whereas theta-band phase patterns differ across stimuli, power patterns do not. We use a simulation model of the single-trial response to spoken sentence stimuli to demonstrate that phase-locked responses to low-frequency modulations of the acoustic signal can account not only for the phase but also for the power results. The simulation offers insight into the interpretation of the empirical results with respect to phase-resetting and power-enhancement models of the evoked response.

  10. A Novel Cell-Based Hybrid Acoustic Wave Biosensor with Impedimetric Sensing Capabilities

    PubMed Central

    Liu, Fei; Li, Fang; Nordin, Anis Nurashikin; Voiculescu, Ioana

    2013-01-01

    A novel multiparametric biosensor system based on living cells will be presented. The biosensor system includes two biosensing techniques on a single device: resonant frequency measurements and electric cell-substrate impedance sensing (ECIS). The multiparametric sensor system is based on the innovative use of the upper electrode of a quartz crystal microbalance (QCM) resonator as working electrode for the ECIS technique. The QCM acoustic wave sensor consists of a thin AT-cut quartz substrate with two gold electrodes on opposite sides. For integration of the QCM with the ECIS technique a semicircular counter electrode was fabricated near the upper electrode on the same side of the quartz crystal. Bovine aortic endothelial live cells (BAECs) were successfully cultured on this hybrid biosensor. Finite element modeling of the bulk acoustic wave resonator using COMSOL simulations was performed. Simultaneous gravimetric and impedimetric measurements performed over a period of time on the same cell culture were conducted to validate the device's sensitivity. The time necessary for the BAEC cells to attach and form a compact monolayer on the biosensor was 35∼45 minutes for 1.5 × 104 cells/cm2 BAECs; 60 minutes for 2.0 × 104 cells/cm2 BAECs; 70 minutes for 3.0 × 104 cells/cm2 BAECs; and 100 minutes for 5.0 × 104 cells/cm2 BAECs. It was demonstrated that this time is the same for both gravimetric and impedimetric measurements. This hybrid biosensor will be employed in the future for water toxicity detection. PMID:23459387

  11. Discrimination of Speech Stimuli Based on Neuronal Response Phase Patterns Depends on Acoustics But Not Comprehension

    PubMed Central

    Poeppel, David

    2010-01-01

    Speech stimuli give rise to neural activity in the listener that can be observed as waveforms using magnetoencephalography. Although waveforms vary greatly from trial to trial due to activity unrelated to the stimulus, it has been demonstrated that spoken sentences can be discriminated based on theta-band (3–7 Hz) phase patterns in single-trial response waveforms. Furthermore, manipulations of the speech signal envelope and fine structure that reduced intelligibility were found to produce correlated reductions in discrimination performance, suggesting a relationship between theta-band phase patterns and speech comprehension. This study investigates the nature of this relationship, hypothesizing that theta-band phase patterns primarily reflect cortical processing of low-frequency (<40 Hz) modulations present in the acoustic signal and required for intelligibility, rather than processing exclusively related to comprehension (e.g., lexical, syntactic, semantic). Using stimuli that are quite similar to normal spoken sentences in terms of low-frequency modulation characteristics but are unintelligible (i.e., their time-inverted counterparts), we find that discrimination performance based on theta-band phase patterns is equal for both types of stimuli. Consistent with earlier findings, we also observe that whereas theta-band phase patterns differ across stimuli, power patterns do not. We use a simulation model of the single-trial response to spoken sentence stimuli to demonstrate that phase-locked responses to low-frequency modulations of the acoustic signal can account not only for the phase but also for the power results. The simulation offers insight into the interpretation of the empirical results with respect to phase-resetting and power-enhancement models of the evoked response. PMID:20484530

  12. Sixteen-Year Change in Acoustic-Admittance Measures among Older Adults: Data from a Population-Based Study

    ERIC Educational Resources Information Center

    Nondahl, David M.; Cruickshanks, Karen J.; Wiley, Terry L.; Tweed, Ted S.; Dalton, Dayna S.

    2013-01-01

    Purpose: The primary purpose of this study was to measure the 16-year change in peak compensated static acoustic admittance (Peak Y[subscript tm]) in a population-based cohort of older adults, and to determine whether age was associated with any observed change in Peak Y[subscript tm]. Other tympanometric measures also were taken and analyzed.…

  13. Security enhanced optical one-time password authentication method by using digital holography

    NASA Astrophysics Data System (ADS)

    Gil, Sang Keun; Jeon, Seok Hee; Jeong, Jong Rae

    2015-03-01

    We propose a new optical one-time password(OTP) authentication method by using digital holography, which enhances security strength in the cryptosystem compared to the conventional electronic OTP method. In this paper, a challenge-response optical OTP authentication based on two-factor authentication is presented by 2-step quadrature phase-shifting digital holography using orthogonal polarization, and two-way authentication is also performed using the challenge-response handshake in both directions. The ID (identification), PW (password) and OTP information are encrypted with a shared key by applying phase-shifting digital holography, and these encrypted information are verified each other by the shared key. Because the encrypted digital holograms which are transmitted to the other party are expressed as random distribution, it guards against a replay attack and results in higher security level. Optically, encrypted digital hologram in our method is Fourier transform hologram and is recorded on CCD with 256 gray-level quantized intensities. The proposed method has an advantage that it does not need a time-synchronized OTP and can be applied to various security services. Computer experiments show that the proposed method is suitable for high secure OTP authentication.

  14. Glider-based Passive Acoustic Monitoring Techniques in the Southern California Region & West Coast Naval Training Range Demonstration of Glider-based Passive Acoustic Monitoring

    DTIC Science & Technology

    2012-09-30

    distribution unlimited 13. SUPPLEMENTARY NOTES The original document contains color images. 14. ABSTRACT 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION...indicate sunset to sunrise , with vertical grid lines marking midnight local time. Figure 2 above shows data obtained from a HARP passive acoustic

  15. High speed 3D surface inspection with digital holography

    NASA Astrophysics Data System (ADS)

    Brunn, Andreas; Aspert, Nicolas; Cuche, Etienne; Emery, Yves; Ettemeyer, Andreas

    2013-01-01

    Digital holography has proven its ability to acquire high accuracy full field 3D data with one single image acquisition. This means that in principle this technique offers the chance to perform 3D serial inspection processes, as well. However, one limitation in digital holography is its limited ability to measure rough surfaces. In the presence of rough surfaces, the magnification of the image has to be increased to capture the required phase information on each camera pixel. However, this leads to significant reduction of inspection speed. If low magnification is selected, the rough surface produces speckles which cannot be treated properly by digital holography algorithms. In this paper, we describe the extension of digital holography to rough surface applications using speckle interferometry technique. This technique is capable of fast inspection of rough surfaces with sub-micrometer accuracy. The principle of this approach is shown and a practical application for 3D surface inspection of wafer cutting processes is given.

  16. Theoretical scheme for simultaneously observing forward-backward photoelectron holography.

    PubMed

    Du, Hongchuan; Wu, Hongmei; Wang, Huiqiao; Yue, Shengjun; Hu, Bitao

    2016-02-15

    Photoelectron angular momentum distribution of He+ driven by a few-cycle laser is investigated numerically. We simultaneously observe two dominant interference patterns with one shot of lasers by solving the 3D time-dependent Schrodinger equation. Analysis of a semiclassical model identifies these two interference patterns as two types of photoelectron holography. The interference pattern with Pz0 is a type of forward rescattering holography, which comes from the interference between direct (reference) and rescattered (signal) forward electrons ionized in the same quarter-cycle. The interference pattern with Pz<0 is a type of backward rescattering holography, which comes from the interference between a direct electron ionized in the third quarter-cycle and rescattered backward electron ionized in the first quarter-cycle. Moreover, we propose a method to distinguish this backward rescattering holography and intracycle interference patterns of direct electrons.

  17. Absorbing New Subjects: Holography as an Analog of Photography

    NASA Astrophysics Data System (ADS)

    Johnston, Sean F.

    2006-05-01

    I discuss the early history of holography and explore how perceptions, applications, and forecasts of the subject were shaped by prior experience. I focus on the work of Dennis Gabor (1900 1979) in England,Yury N. Denisyuk (b. 1924) in the Soviet Union, and Emmett N. Leith (1927 2005) and Juris Upatnieks (b. 1936) in the United States. I show that the evolution of holography was simultaneously promoted and constrained by its identification as an analog of photography, an association that influenced its assessment by successive audiences of practitioners, entrepreneurs, and consumers. One consequence is that holography can be seen as an example of a modern technical subject that has been shaped by cultural influences more powerfully than generally appreciated. Conversely, the understanding of this new science and technology in terms of an older one helps to explain why the cultural effects of holography have been more muted than anticipated by forecasters between the 1960s and 1990s.

  18. Optical HAAR Wavelet Transforms using Computer Generated Holography

    DTIC Science & Technology

    1992-12-17

    This research introduces an optical implementation of the continuous wavelet transform to filter images. The wavelet transform is modeled as a...continuous wavelet transform was performed and that the results compared favorably to digital simulation. Wavelets, Holography, Optical correlators.

  19. Fresnel Lens Scatter Plate for Data Reduction Holography.

    DTIC Science & Technology

    In the patent the holographic apparatus and method uses a Fresnel lens as a scatter plate in data reduction holography. A second embodiment uses a Fresnel lens in series with a fly’s eye lens array.

  20. Development of Acoustic Based, Multi-tasking Sensing and Actuation Capabilities for Gas Turbines

    DTIC Science & Technology

    2007-11-02

    Turbine Combustion, Edwards Brothers: Ann Arbor, 1999. 3 Wright, W, Schindel, D, Hutchins, D, Carpenter, P, Jansen, D, Ultrasonic tomographic...Papers Submitted/Published : Cottet, A., Lieuwen, T., Acoustic Absorption Measurements for Characterization of Gas Mixing, AIAA Paper...2003-3259 presented at the 9th AIAA Aeroacoustics Conference, May 2003. Cottet, A., Lieuwen, T., Gas Mixing Diagnostics Using Acoustic Absorption