Science.gov

Sample records for phased array transducer

  1. A novel serrated columnar phased array ultrasonic transducer

    NASA Astrophysics Data System (ADS)

    Zou, Cheng; Sun, Zhenguo; Cai, Dong; Song, Hongwei; Chen, Qiang

    2016-02-01

    Traditionally, wedges are required to generate transverse waves in a solid specimen and mechanical rotation device is needed for interrogation of a specimen with a hollow bore, such as high speed railway locomotive axles, turbine rotors, etc. In order to eliminate the mechanical rotation process, a novel array pattern of phased array ultrasonic transducers named as serrated columnar phased array ultrasonic transducer (SCPAUT) is designed. The elementary transducers are planar rectangular, located on the outside surface of a cylinder. This layout is aimed to generate electrically rotating transverse waveforms so as to inspect the longitudinal cracks on the outside surface of a specimen which has a hollow bore at the center, such as the high speed railway locomotive axles. The general geometry of the SCPAUT and the inspection system are illustrated. A FEM model and mockup experiment has been carried out. The experiment results are in good agreement with the FEM simulation results.

  2. Thermal dispersion method for an ultrasonic phased-array transducer

    NASA Astrophysics Data System (ADS)

    Choi, Euna; Lee, Wonseok; Roh, Yongrae

    2016-07-01

    When the driving voltage of an ultrasonic transducer is increased to improve the quality of ultrasound images, heat is generated inside the transducer, which can burn the patient’s skin and degrade transducer performance. In this study, the method to disperse the heat inside an ultrasonic phased-array transducer has been examined. The mechanism of temperature rise due to heat generation inside the transducer was investigated by numerical analysis and the effects of the thermal properties of the components of the transducer such as specific heat and thermal conductivity on the temperature rise were analyzed. On the basis of the results, a heat-dispersive structure was devised to reduce the temperature at the surface of the acoustic lens of the transducer. Prototype transducers were fabricated to check the efficacy of the heat-dispersive structure. By experiments, we have confirmed that the new heat-dispersive structure can reduce the internal temperature by as much as 50% in comparison with the conventional structure, which confirms the validity of the thermal dispersion mechanism developed in this work.

  3. Simplified System Efficiency Functions for Linear Phased-Array Transducers

    NASA Astrophysics Data System (ADS)

    Margetan, F. J.; Gray, T. A.; Huang, Ruiju

    2010-02-01

    Computer models are often used to simulate ultrasonic inspections of industrial components. One ingredient of such simulations is a frequency dependent function which describes the efficiency of the inspection system for converting electrical energy to sound and vice versa. For a phased-array transducer there are many such efficiency functions, namely one for each independent pair of piezoelectric elements. In this paper we describe a simplified, approximate approach for specifying these functions. Element-to-element differences are accounted for by two "residual" parameters: (1) a strength factor which describes the relative "hotness" of an element compared to its peers; and (2) a time delay which describes the extent to which an element fires later or earlier than its peers when all elements are instructed to fire in unison. These residuals are used to relate the system efficiency function for any pair of elements to that of an average efficiency which can be readily measured. The use of this approach is demonstrated using front-wall and back-wall responses from a stainless steel block, as acquired using a 5-MHz, 32-element, linear phased-array transducer. Good agreement was found between measured and simulated surface responses.

  4. Sparsely Sampled Phase-Insensitive Ultrasonic Transducer Arrays

    NASA Technical Reports Server (NTRS)

    Johnston, Patrick H.

    1992-01-01

    Three methods of interpretation of outputs from sparsely sampled two-dimensional array of receiving ultrasonic transducers used in transmission experiments investigated. Methods are: description of sampled beam in terms of first few spatial moments of sampled distribution of energy; use of signal-dependent cutoff to limit extent of effective receiver aperture; and use of spatial interpolation to increase apparent density of sampling during computation. Methods reduce errors in computations of shapes of ultrasonic beams.

  5. Adhesive defect detection in composite adhesive joints using phased array transducers

    NASA Astrophysics Data System (ADS)

    Ren, Baiyang; Lissenden, Cliff J.

    2015-03-01

    Composite materials are widely used in aircraft structures due to their high specific stiffness and strength. The laminated nature of composite structures makes them subject to disbond and delamination. These types of defects will compromise the integrity of the structure and therefore need to be monitored. To monitor aircraft structures, light weight transducers capable of large area coverage are beneficial. Ultrasonic guided waves are able to travel long distance and are sensitive to localized defects. The multi-modal characteristic of propagating guided waves requires optimal mode selection and excitation. Phased array transducers provide good versatility for optimal mode excitation since they can excite different guided wave modes preferentially. Phased array transducers designed for structural health monitoring (SHM) applications are employed in this work to study the interaction between adhesive defects and guided wave modes. Amplitude ratios and wave packet composition are utilized as defect indicators that are uniquely available due to the phased array transducers.

  6. Phased annular array transducers for omnidirectional guided wave mode control in isotropic plate like structures

    NASA Astrophysics Data System (ADS)

    Koduru, Jaya P.; Momeni, Sepandarmaz; Rose, Joseph L.

    2013-12-01

    Ultrasonic guided waves are fast emerging as a reliable tool for continuous structural health monitoring. Their multi-modal nature along with their long range propagation characteristics offer several possibilities for interrogating structures. Transducers commonly used to generate guided waves in structures excite multiple modes at any frequency; their complex scattering and reflection from defects and boundaries often complicates the extraction of useful information. Often it is desirable to control the guided wave modes propagating in a structure to take advantage of their unique properties for different applications. Earlier attempts at guided wave mode control involved developing fixed wavelength linear and annular array transducers. Their only disadvantage is that the transducer is limited to a particular wavelength and a change in wavelength necessitates a change in the transducer. In this paper, we propose the development of an annular array transducer that can generate mode controlled omnidirectional guided waves by independently controlling the amplitude and phase of the array elements. A simplified actuator model that approximates the transducer loading on the structure to a constant pressure load under the array elements is assumed and an optimization problem is set up to compute the excitation voltage and phase of the elements. A five element annular array transducer is designed utilizing 1-3 type piezocomposite materials. The theoretical computations are experimentally verified on an aluminum plate like structure by exciting A0 and S0 guided wave modes.

  7. Nonparaxial multi-Gaussian beam models and measurement models for phased array transducers.

    PubMed

    Zhao, Xinyu; Gang, Tie

    2009-01-01

    A nonparaxial multi-Gaussian beam model is proposed in order to overcome the limitation that paraxial Gaussian beam models lose accuracy in simulating the beam steering behavior of phased array transducers. Using this nonparaxial multi-Gaussian beam model, the focusing and steering sound fields generated by an ultrasonic linear phased array transducer are calculated and compared with the corresponding results obtained by paraxial multi-Gaussian beam model and more exact Rayleigh-Sommerfeld integral model. In addition, with help of this novel nonparaxial method, an ultrasonic measurement model is provided to investigate the sensitivity of linear phased array transducers versus steering angles. Also the comparisons of model predictions with experimental results are presented to certify the accuracy of this provided measurement model. PMID:18774152

  8. Damage localization in aluminum plate with compact rectangular phased piezoelectric transducer array

    NASA Astrophysics Data System (ADS)

    Liu, Zenghua; Sun, Kunming; Song, Guorong; He, Cunfu; Wu, Bin

    2016-03-01

    In this work, a detection method for the damage in plate-like structure with a compact rectangular phased piezoelectric transducer array of 16 piezoelectric elements was presented. This compact array can not only detect and locate a single defect (through hole) in plate, but also identify multi-defects (through holes and surface defect simulated by an iron pillar glued to the plate). The experiments proved that the compact rectangular phased transducer array could detect the full range of plate structures and implement multiple-defect detection simultaneously. The processing algorithm proposed in this paper contains two parts: signal filtering and damage imaging. The former part was used to remove noise from signals. Continuous wavelet transform was applicable to signal filtering. Continuous wavelet transform can provide a plot of wavelet coefficients and the signal with narrow frequency band can be easily extracted from the plot. The latter part of processing algorithm was to implement damage detection and localization. In order to accurately locate defects and improve the imaging quality, two images were obtained from amplitude and phase information. One image was obtained with the Total Focusing Method (TFM) and another phase image was obtained with the Sign Coherence Factor (SCF). Furthermore, an image compounding technique for compact rectangular phased piezoelectric transducer array was proposed in this paper. With the proposed technique, the compounded image can be obtained by combining TFM image with SCF image, thus greatly improving the resolution and contrast of image.

  9. Investigating a stepped ultrasonic phased array transducer for the evaluation and characterization of defects

    NASA Astrophysics Data System (ADS)

    Bohenick, M.; Blickley, E.; Tittmann, B. R.; Kropf, M.

    2007-04-01

    Previous work has led to the design, simulation, and development of a linear phased array transducer. The intention of the array is to be used as a non-destructive ultrasonic device to monitor and evaluate the health of a given specimen. The phased array has been manufactured and tested for the detection and characterization of defects on a target. The array was fabricated with a four-row "stepped" design with four wires to transfer data and one wire for grounding. The "stepped" design allows for the interrogation of a larger region using time delays and beam sweeping without the use of additional electrical channels. The array was designed to be utilized in a water immersion environment with about one inch between the array and the target specimen. An OmniScan MX system was used to operate the phased array and perform real-time linear and sectorial scans on a set of rectangular plates. S-scans allow for beam sweeping over an angle range as well as adjustments for time delays and a true-depth display. The array was operated with sixteen active elements and an angle range of 0 to 30 degrees. The phased array was tested with a variety of targets and was used to investigate and characterize different types of defects such as cracking, warping, and corrosion. The ability of the phased array to distinguish between defect types as well as resolve defect size was evaluated.

  10. Saft-reconstruction in ultrasonic immersion technique using phased array transducers

    NASA Astrophysics Data System (ADS)

    Kitze, J.; Prager, J.; Boehm, R.; Völz, U.; Montag, H.-J.

    2012-05-01

    The two main preconditions for the application of the Synthetic Aperture Focusing Technique (SAFT) are: (i) a large divergence of the sound beam of the transducer and (ii) an exact knowledge about the sound propagation path. These requirements are easily fulfilled for point sources directly mounted on the surface of the specimen. In many cases, however, the transducer is wedge mounted and/or coupled using a water delay line, e.g. in immersion technique. These delay lines change the beam index and the propagation path has to be evaluated for each pixel separately considering Fermat's principle. Using phased array transducers, a sector scan can improve the divergence of the sound beam. The introduced method combines the advantages of using a phased array transducer in immersion technique to improve SAFT reconstruction. An algorithm is presented accounting the influence of the delay line on the reconstruction method. The applicability of the algorithm is shown by validation with simulated echo responses and with experimental results collected from a specimen with artificial flaws.

  11. A 1372-element Large Scale Hemispherical Ultrasound Phased Array Transducer for Noninvasive Transcranial Therapy

    SciTech Connect

    Song, Junho; Hynynen, Kullervo

    2009-04-14

    Noninvasive transcranial therapy using high intensity focused ultrasound transducers has attracted high interest as a promising new modality for the treatments of brain related diseases. We describe the development of a 1372 element large scale hemispherical ultrasound phased array transducer operating at a resonant frequency of 306 kHz. The hemispherical array has a diameter of 31 cm and a 15.5 cm radius of curvature. It is constructed with piezoelectric (PZT-4) tube elements of a 10 mm in diameter, 6 mm in length and 1.4 mm wall thickness. Each element is quasi-air backed by attaching a cork-rubber membrane on the back of the element. The acoustic efficiency of the element is determined to be approximately 50%. The large number of the elements delivers high power ultrasound and offers better beam steering and focusing capability. Comparisons of sound pressure-squared field measurements with theoretical calculations in water show that the array provides good beam steering and tight focusing capability over an efficient volume of approximately 100x100x80 mm{sup 3} with nominal focal spot size of approximately 2.3 mm in diameter at -6 dB. We also present its beam steering and focusing capability through an ex vivo human skull by measuring pressure-squared amplitude after phase corrections. These measurements show the same efficient volume range and focal spot sizes at -6 dB as the ones in water without the skull present. These results indicate that the array is sufficient for use in noninvasive transcranial ultrasound therapy.

  12. A 1372-element Large Scale Hemispherical Ultrasound Phased Array Transducer for Noninvasive Transcranial Therapy

    NASA Astrophysics Data System (ADS)

    Song, Junho; Hynynen, Kullervo

    2009-04-01

    Noninvasive transcranial therapy using high intensity focused ultrasound transducers has attracted high interest as a promising new modality for the treatments of brain related diseases. We describe the development of a 1372 element large scale hemispherical ultrasound phased array transducer operating at a resonant frequency of 306 kHz. The hemispherical array has a diameter of 31 cm and a 15.5 cm radius of curvature. It is constructed with piezoelectric (PZT-4) tube elements of a 10 mm in diameter, 6 mm in length and 1.4 mm wall thickness. Each element is quasi-air backed by attaching a cork-rubber membrane on the back of the element. The acoustic efficiency of the element is determined to be approximately 50%. The large number of the elements delivers high power ultrasound and offers better beam steering and focusing capability. Comparisons of sound pressure-squared field measurements with theoretical calculations in water show that the array provides good beam steering and tight focusing capability over an efficient volume of approximately 100×100×80 mm3 with nominal focal spot size of approximately 2.3 mm in diameter at -6 dB. We also present its beam steering and focusing capability through an ex vivo human skull by measuring pressure-squared amplitude after phase corrections. These measurements show the same efficient volume range and focal spot sizes at -6 dB as the ones in water without the skull present. These results indicate that the array is sufficient for use in noninvasive transcranial ultrasound therapy.

  13. Broadband phased array transducer design with frequency-controlled two-dimensional capability

    NASA Astrophysics Data System (ADS)

    Hanafy, Amin

    1998-05-01

    With the wide acceptance of ultrasound medical imaging as the non-invasive diagnostic modality of choice, sonography equipment must offer the tools to complete the diagnosis, including multi-frequency operation for difficult-to-image patients. The trade-off between greater depth of penetration at low frequency for large organs and the improved detail resolution at high frequency is an essential capability that necessitates wideband transducer design and matching system hardware. This paper presents a phased array transducer design with variable ceramic thickness in the elevation direction. The design offers tow major contributions: first, -6dB round trip fractional bandwidth is increased by as much as 120 percent. This is done by controlling the thickness of the crystal from the middle to the outer edge. Since each sampling point in the crystal resonates freely at half wavelength in its fundamental mode, extended bandwidth is achieved for the single element in the phased array. This method has considerable advantage over the usual methods, such as backing the transducer with a matched lossy material. The drawback to backing the transducer is that the acoustic power consumed by the backing represents a severe insertion loss, especially if optimum bandwidth is desired. The second contribution of this design is the use of software to control the elevation slice thickness with axial symmetry around the 2D imaging plane. This is done by controlling the excitation frequency on transmit, and filtering on receive, thereby controlling the transmit and receive apertures independently during imaging. Compared to the standard elevation sampled 1.5D or 2D arrays with an increased number of hardware system channels and extensive cable wires needed, the new design offers simplicity and cost effectiveness. This represents a key development, especially with the advent of second harmonic imaging, both from a point of view of bandwidth requirement and slice thickness on receive. This

  14. Development of a C-Scan phased array ultrasonic imaging system using a 64-element 35MHz transducer

    NASA Astrophysics Data System (ADS)

    Zheng, Fan; Hu, Changhong; Zhang, Lequan; Snook, Kevin; Liang, Yu; Hackenberger, Wesley S.; Liu, Ruibin; Geng, Xuecang; Jiang, Xiaoning; Shung, K. Kirk

    2011-04-01

    Phased array imaging systems provide the features of electronic beam steering and dynamic depth focusing that cannot be obtained with conventional linear array systems. This paper presents a system design of a digital ultrasonic imaging system, which is capable of handling a 64-element 35MHz center frequency phased array transducer. The system consists of 5 parts: an analog front-end, a data digitizer, a DSP based beamformer, a computer controlled motorized linear stage, and a computer for post image processing and visualization. Using a motorized linear stage, C-scan images, parallel to the surface of scanned objects may be generated. This digital ultrasonic imaging system in combination a 35 MHz phased array appears to be a promising tool for NDT applications with high spatial resolution. It may also serve as an excellent research platform for high frequency phased array design and testing as well as ultrasonic array signal algorithm developing using system's raw RF data acquisition function.

  15. Analog circuit for controlling acoustic transducer arrays

    DOEpatents

    Drumheller, Douglas S.

    1991-01-01

    A simplified ananlog circuit is presented for controlling electromechanical transducer pairs in an acoustic telemetry system. The analog circuit of this invention comprises a single electrical resistor which replaces all of the digital components in a known digital circuit. In accordance with this invention, a first transducer in a transducer pair of array is driven in series with the resistor. The voltage drop across this resistor is then amplified and used to drive the second transducer. The voltage drop across the resistor is proportional and in phase with the current to the transducer. This current is approximately 90 degrees out of phase with the driving voltage to the transducer. This phase shift replaces the digital delay required by the digital control circuit of the prior art.

  16. Phase insensitive acoustoelectric transducer

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.

    1978-01-01

    Conventional ultrasonic transducers transform acoustic waves into electrical signals preserving phase and amplitude information. When the acoustic wavelength is significantly smaller than the transducer diameter, severe phase modulation of the electrical signal can occur. This results in anomalous attenuation measurements, background noise in nondestructive evaluation, and in general complicates data interpretation. This article describes and evaluates a phase-insensitive transducer based on the acoustoelectric effect. Theory of operation of the acoustoelectric transducer (AET) is discussed, and some optimization procedures outlined for its use. Directivity data for the AET are contrasted with a conventional piezoelectric transducer. In addition, transmission scanning data of phantom flaws in metal plates are presented for both transducers and demonstrate a significant improvement in resolution with the AET.

  17. Development of a spherically focused phased array transducer for ultrasonic image-guided hyperthermia

    NASA Astrophysics Data System (ADS)

    Liu, Jingfei; Foiret, Josquin; Stephens, Douglas N.; Le Baron, Olivier; Ferrara, Katherine W.

    2016-07-01

    A 1.5 MHz prolate spheroidal therapeutic array with 128 circular elements was designed to accommodate standard imaging arrays for ultrasonic image-guided hyperthermia. The implementation of this dual-array system integrates real-time therapeutic and imaging functions with a single ultrasound system (Vantage 256, Verasonics). To facilitate applications involving small animal imaging and therapy the array was designed to have a beam depth of field smaller than 3.5 mm and to electronically steer over distances greater than 1 cm in both the axial and lateral directions. In order to achieve the required f number of 0.69, 1-3 piezocomposite modules were mated within the transducer housing. The performance of the prototype array was experimentally evaluated with excellent agreement with numerical simulation. A focal volume (2.70 mm (axial)  ×  0.65 mm (transverse)  ×  0.35 mm (transverse)) defined by the  ‑6 dB focal intensity was obtained to address the dimensions needed for small animal therapy. An electronic beam steering range defined by the  ‑3 dB focal peak intensity (17 mm (axial)  ×  14 mm (transverse)  ×  12 mm (transverse)) and  ‑8 dB lateral grating lobes (24 mm (axial)  ×  18 mm (transverse)  ×  16 mm (transverse)) was achieved. The combined testing of imaging and therapeutic functions confirmed well-controlled local heating generation and imaging in a tissue mimicking phantom. This dual-array implementation offers a practical means to achieve hyperthermia and ablation in small animal models and can be incorporated within protocols for ultrasound-mediated drug delivery.

  18. Development of a spherically focused phased array transducer for ultrasonic image-guided hyperthermia.

    PubMed

    Liu, Jingfei; Foiret, Josquin; Stephens, Douglas N; Le Baron, Olivier; Ferrara, Katherine W

    2016-07-21

    A 1.5 MHz prolate spheroidal therapeutic array with 128 circular elements was designed to accommodate standard imaging arrays for ultrasonic image-guided hyperthermia. The implementation of this dual-array system integrates real-time therapeutic and imaging functions with a single ultrasound system (Vantage 256, Verasonics). To facilitate applications involving small animal imaging and therapy the array was designed to have a beam depth of field smaller than 3.5 mm and to electronically steer over distances greater than 1 cm in both the axial and lateral directions. In order to achieve the required f number of 0.69, 1-3 piezocomposite modules were mated within the transducer housing. The performance of the prototype array was experimentally evaluated with excellent agreement with numerical simulation. A focal volume (2.70 mm (axial)  ×  0.65 mm (transverse)  ×  0.35 mm (transverse)) defined by the  -6 dB focal intensity was obtained to address the dimensions needed for small animal therapy. An electronic beam steering range defined by the  -3 dB focal peak intensity (17 mm (axial)  ×  14 mm (transverse)  ×  12 mm (transverse)) and  -8 dB lateral grating lobes (24 mm (axial)  ×  18 mm (transverse)  ×  16 mm (transverse)) was achieved. The combined testing of imaging and therapeutic functions confirmed well-controlled local heating generation and imaging in a tissue mimicking phantom. This dual-array implementation offers a practical means to achieve hyperthermia and ablation in small animal models and can be incorporated within protocols for ultrasound-mediated drug delivery. PMID:27353347

  19. An MR-compliant phased-array HIFU transducer with augmented steering range, dedicated to abdominal thermotherapy

    NASA Astrophysics Data System (ADS)

    Auboiroux, Vincent; Dumont, Erik; Petrusca, Lorena; Viallon, Magalie; Salomir, Rares

    2011-06-01

    A novel architecture for a phased-array high intensity focused ultrasound (HIFU) device was investigated, aiming to increase the capabilities of electronic steering without reducing the size of the elementary emitters. The principal medical application expected to benefit from these developments is the time-effective sonication of large tumours in moving organs. The underlying principle consists of dividing the full array of transducers into multiple sub-arrays of different resonance frequencies, with the reorientation of these individual emitters, such that each sub-array can focus within a given spatial zone. To enable magnetic resonance (MR) compatibility of the device and the number of output channels from the RF generator to be halved, a passive spectral multiplexing technique was used, consisting of parallel wiring of frequency-shifted paired piezoceramic emitters with intrinsic narrow-band response. Two families of 64 emitters (circular, 5 mm diameter) were mounted, with optimum efficiency at 0.96 and 1.03 MHz, respectively. Two different prototypes of the HIFU device were built and tested, each incorporating the same two families of emitters, but differing in the shape of the rapid prototyping plastic support that accommodated the transducers (spherical cap with radius of curvature/aperture of 130 mm/150 mm and, respectively, 80 mm/110 mm). Acoustic measurements, MR-acoustic radiation force imaging (ex vivo) and MR-thermometry (ex vivo and in vivo) were used for the characterization of the prototypes. Experimental results demonstrated an augmentation of the steering range by 80% along one preferentially chosen axis, compared to a classic spherical array of the same total number of elements. The electric power density provided to the piezoceramic transducers exceeded 50 W cm-2 CW, without circulation of coolant water. Another important advantage of the current approach is the versatility of reshaping the array at low cost.

  20. Quantitative shear wave optical coherence elastography (SW-OCE) with acoustic radiation force impulses (ARFI) induced by phase array transducer

    NASA Astrophysics Data System (ADS)

    Song, Shaozhen; Le, Nhan Minh; Wang, Ruikang K.; Huang, Zhihong

    2015-03-01

    Shear Wave Optical Coherence Elastography (SW-OCE) uses the speed of propagating shear waves to provide a quantitative measurement of localized shear modulus, making it a valuable technique for the elasticity characterization of tissues such as skin and ocular tissue. One of the main challenges in shear wave elastography is to induce a reliable source of shear wave; most of nowadays techniques use external vibrators which have several drawbacks such as limited wave propagation range and/or difficulties in non-invasive scans requiring precisions, accuracy. Thus, we propose linear phase array ultrasound transducer as a remote wave source, combined with the high-speed, 47,000-frame-per-second Shear-wave visualization provided by phase-sensitive OCT. In this study, we observed for the first time shear waves induced by a 128 element linear array ultrasound imaging transducer, while the ultrasound and OCT images (within the OCE detection range) were triggered simultaneously. Acoustic radiation force impulses are induced by emitting 10 MHz tone-bursts of sub-millisecond durations (between 50 μm - 100 μm). Ultrasound beam steering is achieved by programming appropriate phase delay, covering a lateral range of 10 mm and full OCT axial (depth) range in the imaging sample. Tissue-mimicking phantoms with agarose concentration of 0.5% and 1% was used in the SW-OCE measurements as the only imaging samples. The results show extensive improvements over the range of SW-OCE elasticity map; such improvements can also be seen over shear wave velocities in softer and stiffer phantoms, as well as determining the boundary of multiple inclusions with different stiffness. This approach opens up the feasibility to combine medical ultrasound imaging and SW-OCE for high-resolution localized quantitative measurement of tissue biomechanical property.

  1. Wideband focused transducer array for optoacoustic tomography

    NASA Astrophysics Data System (ADS)

    Simonova, V. A.; Khokhlova, T. D.; Karabutov, A. A.

    2009-11-01

    The calculation procedure of the parameters of a multielement transducer array for the optoacoustic tomography of biological objects with high spatial resolution values is proposed. A multielement transducer with given spatial resolution values in three dimensions has been developed based on the proposed procedure for the early detection of breast cancer. The transducer array consists of a set of 8 linear PVDF piezoelectric films located on a plane and a focusing cylindrical acoustic lens. A map of the transducer’s focal area and point spread function have been measured using the constructed transducer array. Spatial resolutions of the transducer array obtained experimentally are in agreement with their calculated values.

  2. Reflection at a liquid-solid interface of a transient ultrasonic field radiated by a linear phased array transducer.

    PubMed

    Maghlaoui, Nadir; Belgroune, Djema; Ourak, Mohamed; Djelouah, Hakim

    2016-09-01

    In order to put in evidence the specular reflection and the non-specular reflection in the transient case, we have used a model for the study of the transient ultrasonic waves radiated by a linear phased array transducer in a liquid and reflected by a solid plane interface. This method is an extension of the angular spectrum method to the transient case where the reflection at the plane interface is taken into account by using the reflection coefficient for harmonic plane waves. The results obtained highlighted the different components of the ultrasonic field: the direct and edge waves as well as the longitudinal head waves or leaky Rayleigh waves. The transient representation of these waves have been carefully analyzed and discussed by the rays model. Instantaneous cartographies allowed a clear description of all the waves which appear at the liquid-solid interface. The obtained results have been compared to those obtained with a finite element method package. PMID:27290651

  3. Development of electromagnetic acoustic transducer (EMAT) phased arrays for SFR inspection

    SciTech Connect

    Le Bourdais, Florian; Marchand, Benoît

    2014-02-18

    A long-standing problem for Sodium cooled Fast Reactor (SFR) instrumentation is the development of efficient under-sodium visualization systems adapted to the hot and opaque sodium environment. Electromagnetic Acoustic Transducers (EMAT) are potential candidates for a new generation of Ultrasonic Testing (UT) probes well-suited for SFR inspection that can overcome drawbacks of classical piezoelectric probes in sodium environment. Based on the use of new CIVA simulation tools, we have designed and optimized an advanced EMAT probe for under-sodium visualization. This has led to the development of a fully functional L-wave EMAT sensing system composed of 8 elements and a casing withstanding 200° C sodium inspection. Laboratory experiments demonstrated the probe's ability to sweep an ultrasonic beam to an angle of 15 degrees. Testing in a specialized sodium facility has shown that it was possible to obtain pulse-echo signals from a target under several different angles from a fixed position.

  4. Development of electromagnetic acoustic transducer (EMAT) phased arrays for SFR inspection

    NASA Astrophysics Data System (ADS)

    Le Bourdais, Florian; Marchand, Benoît

    2014-02-01

    A long-standing problem for Sodium cooled Fast Reactor (SFR) instrumentation is the development of efficient under-sodium visualization systems adapted to the hot and opaque sodium environment. Electromagnetic Acoustic Transducers (EMAT) are potential candidates for a new generation of Ultrasonic Testing (UT) probes well-suited for SFR inspection that can overcome drawbacks of classical piezoelectric probes in sodium environment. Based on the use of new CIVA simulation tools, we have designed and optimized an advanced EMAT probe for under-sodium visualization. This has led to the development of a fully functional L-wave EMAT sensing system composed of 8 elements and a casing withstanding 200° C sodium inspection. Laboratory experiments demonstrated the probe's ability to sweep an ultrasonic beam to an angle of 15 degrees. Testing in a specialized sodium facility has shown that it was possible to obtain pulse-echo signals from a target under several different angles from a fixed position.

  5. Crack orientation and depth estimation in a low-pressure turbine disc using a phased array ultrasonic transducer and an artificial neural network.

    PubMed

    Yang, Xiaoxia; Chen, Shili; Jin, Shijiu; Chang, Wenshuang

    2013-01-01

    Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN), is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF) neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks. PMID:24064602

  6. Crack Orientation and Depth Estimation in a Low-Pressure Turbine Disc Using a Phased Array Ultrasonic Transducer and an Artificial Neural Network

    PubMed Central

    Yang, Xiaoxia; Chen, Shili; Jin, Shijiu; Chang, Wenshuang

    2013-01-01

    Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN), is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF) neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks. PMID:24064602

  7. Simulation study of a chaotic cavity transducer based virtual phased array used for focusing in the bulk of a solid material.

    PubMed

    Delrue, Steven; Van Den Abeele, Koen; Matar, Olivier Bou

    2016-04-01

    In acoustic and ultrasonic non-destructive testing techniques, it is sometimes beneficial to concentrate sound energy at a chosen location in space and at a specific instance in time, for example to improve the signal-to-noise ratio or activate the nonlinearity of damage features. Time Reversal (TR) techniques, taking advantage of the reversible character of the wave equation, are particularly suited to focus ultrasonic waves in time and space. The characteristics of the energy focusing in solid media using principles of time reversed acoustics are highly influenced by the nature and dimensions of the medium, the number of transducers and the length of the received signals. Usually, a large number of transducers enclosing the domain of interest is needed to improve the quality of the focusing. However, in the case of highly reverberant media, the number of transducers can be reduced to only one (single-channel TR). For focusing in a non-reverberant medium, which is impossible when using only one source, an adaptation of the single-channel reciprocal TR procedure has been recently suggested by means of a Chaotic Cavity Transducer (CCT), a single element transducer glued on a cavity of chaotic shape. In this paper, a CCT is used to focus elastic energy, at different times, in different points along a predefined line on the upper surface of a thick solid sample. Doing so, all focusing points can act as a virtual phased array transducer, allowing to focus in any point along the depth direction of the sample. This is impossible using conventional reciprocal TR, as you need to have access to all points in the bulk of the material for detecting signals to be used in the TR process. To asses and provide a better understanding of this concept, a numerical study has been developed, allowing to verify the basic concepts of the virtual phased array and to illustrate multi-component time reversal focusing in the bulk of a solid material. PMID:26845370

  8. Modal content based damage indicators and phased array transducers for structural health monitoring of aircraft structures using ultrasonic guided waves

    NASA Astrophysics Data System (ADS)

    Ren, Baiyang

    Composite materials, especially carbon fiber reinforced polymers (CFRP), have been widely used in the aircraft industry because of their high specific strength and stiffness, resistance to corrosion and good fatigue life. Due to their highly anisotropic material properties and laminated structures, joining methods like bolting and riveting are no longer appropriate for joining CFRP since they initiate defects during the assembly and severely compromise the integrity of the structure; thus new techniques for joining CFRP are highly demanded. Adhesive bonding is a promising method because it relieves stress concentration, reduces weight and provides smooth surfaces. Additionally, it is a low-cost alternative to the co-cured method which is currently used to manufacture components of aircraft fuselage. Adhesive defects, disbonds at the interface between adherend and adhesive layer, are focused on in this thesis because they can be initialized by either poor surface preparation during the manufacturing or fatigue loads during service. Aircraft need structural health monitoring (SHM) systems to increase safety and reduce loss, and adhesive bonds usually represent the hotspots of the assembled structure. There are many nondestructive evaluation (NDE) methods for bond inspection. However, these methods cannot be readily integrated into an SHM system because of the bulk size and weight of the equipment and requirement of accessibility to one side of the bonded joint. The first objective of this work is to develop instruments, actuators, sensors and a data acquisition system for SHM of bond lines using ultrasonic guided waves which are well known to be able to cover large volume of the structure and inaccessible regions. Different from widely used guided wave sensors like PZT disks, the new actuators, piezoelectric fiber composite (PFC) phased array transducers0 (PAT), can control the modal content of the excited waves and the new sensors, polyvinylidene fluoride (PVDF

  9. Sector array transducers for vibro-acoustography

    NASA Astrophysics Data System (ADS)

    Silva, Glauber; Chen, Shigao; Kinnick, Randall; Greenleaf, James; Fatemi, Mostafa

    2003-10-01

    Vibro-acoustography is an imaging technique that maps the acoustic response of an object to a localized harmonic radiation force. This force is generated by two interfering continuous-wave ultrasound beams at slightly different frequencies f1 and f2. The system point-spread function (PSF) is related to the radiation force on a point-target. Imaging artifacts depend on the PSF sidelobes, which can be reduced by mismatching the sidelobes of each ultrasound beam. Here, we propose a beamforming approach based on an 8-element sector transducer with consecutive elements alternately driven at f1 and f2. The transducer generates two ultrasound beams skewed by 22.5° with respect to each other. The system PSF is analytically derived. The theory is validated by experiments using a small steel sphere (radius =0.2 mm) as a point-target. A laser vibrometer is used to measure the vibration of the sphere and evaluate the PSF of the system. Theoretically, the PSF sidelobes are under -15.8 dB in eight spots circularly distributed and separated by 22.5°, which agrees with the experimental results. Simulation shows that with 16 elements sidelobes are under -35.2 dB. In conclusion, sector transducers for vibro-acoustography may have lower sidelobes as the number of array elements is increased. [Work supported by Grant Nos. EB00535-01, EB2640, and IMG0100744.

  10. Inter-costal Liver Ablation Under Real Time MR-Thermometry With Partial Activation Of A HIFU Phased Array Transducer

    NASA Astrophysics Data System (ADS)

    Quesson, Bruno; Merle, Mathilde; Köhler, Max; Mougenot, Charles; Roujol, Sebastien; de Senneville, Baudouin Denis; Moonen, Chrit

    2010-03-01

    HIFU ablation of tumours located inside the liver is hampered by the rib cage, which partially obstructs the beam path and may create adverse effects such as skin burns. This study presents a method for selectively deactivating the transducer elements causing undesired temperature increases near the bones. A manual segmentation of the bones visualized on 3D anatomical MR images acquired prior to sonication was performed to identify the beam obstruction. The resulting mask was projected (ray tracing starting from the focal point) on the transducer and elements with more than 50% obstruction of their active surface were deactivated. The effectiveness of the method for HIFU ablations is demonstrated ex vivo and in vivo in the liver of pigs with real-time MR thermometry, using the proton resonant frequency (PRF) method. For both ex vivo and in vivo experiments, the temperature increase near the bones was significantly reduced when the elements located in front of the ribs were deactivated. The temperature evolution at the focal point were similar, indicative of the absence of loss of heating efficacy when the elements were deactivated. This method is simple, rapid and reliable and allows to perform intercostal MRgHIFU ablation of the liver while sparing the ribs.

  11. Linear-array ultrasonic waveguide transducer for under sodium viewing.

    SciTech Connect

    Sheen, S. H.; Chien, H. T.; Wang, K.; Lawrence, W. P.; Engel, D.; Nuclear Engineering Division

    2010-09-01

    In this report, we first present the basic design of a low-noise waveguide and its performance followed by a review of the array transducer technology. The report then presents the concept and basic designs of arrayed waveguide transducers that can apply to under-sodium viewing for in-service inspection of fast reactors. Depending on applications, the basic waveguide arrays consist of designs for sideway and downward viewing. For each viewing application, two array geometries, linear and circular, are included in design analysis. Methods to scan a 2-D target using a linear array waveguide transducer are discussed. Future plan to develop a laboratory array waveguide prototype is also presented.

  12. Highly reliable multisensor array (MSA) smart transducers

    NASA Astrophysics Data System (ADS)

    Perotti, José; Lucena, Angel; Mackey, Paul; Mata, Carlos; Immer, Christopher

    2006-05-01

    Many developments in the field of multisensor array (MSA) transducers have taken place in the last few years. Advancements in fabrication technology, such as Micro-Electro-Mechanical Systems (MEMS) and nanotechnology, have made implementation of MSA devices a reality. NASA Kennedy Space Center (KSC) has been developing this type of technology because of the increases in safety, reliability, and performance and the reduction in operational and maintenance costs that can be achieved with these devices. To demonstrate the MSA technology benefits, KSC quantified the relationship between the number of sensors (N) and the associated improvement in sensor life and reliability. A software algorithm was developed to monitor and assess the health of each element and the overall MSA. Furthermore, the software algorithm implemented criteria on how these elements would contribute to the MSA-calculated output to ensure required performance. The hypothesis was that a greater number of statistically independent sensor elements would provide a measurable increase in measurement reliability. A computer simulation was created to answer this question. An array of N sensors underwent random failures in the simulation and a life extension factor (LEF equals the percentage of the life of a single sensor) was calculated by the program. When LEF was plotted as a function of N, a quasiexponential behavior was detected with marginal improvement above N = 30. The hypothesis and follow-on simulation results were then corroborated experimentally. An array composed of eight independent pressure sensors was fabricated. To accelerate sensor life cycle and failure and to simulate degradation over time, the MSA was exposed to an environmental tem-perature of 125°C. Every 24 hours, the experiment's environmental temperature was returned to ambient temperature (27°C), and the outputs of all the MSA sensor elements were measured. Once per week, the MSA calibration was verified at five different

  13. Focal Length Controllable Ultrasonic Array Transducer with Adjustable Curvature

    NASA Astrophysics Data System (ADS)

    Kim, Jungsoon; Kim, Moojoon; Ha, Kanglyel

    2012-07-01

    In the underwater imaging field, the control of the focal length of a transducer is very useful. As one of the control methods, we suggested an ultrasonic array transducer with adjustable curvature by using air pressure. The curvature of the transducer was investigated according to the air pressure level in the back space of the transducer. Concave-, planar-, and convex-type transducers were obtained with different air pressure levels. The acoustic fields of the transducer were measured for different shapes of the radiation surface.

  14. Electret Acoustic Transducer Array For Computerized Ultrasound Risk Evaluation System

    DOEpatents

    Moore, Thomas L.; Fisher, Karl A.

    2005-08-09

    An electret-based acoustic transducer array is provided and may be used in a system for examining tissue. The acoustic transducer array is formed with a substrate that has a multiple distinct cells formed therein. Within each of the distinct cells is positioned an acoustic transducing element formed of an electret material. A conductive membrane is formed over the distinct cells and may be flexible.

  15. Multiple matching scheme for broadband 0.72Pb(Mg1∕3Nb2∕3)O3−0.28PbTiO3 single crystal phased-array transducer

    PubMed Central

    Lau, S. T.; Li, H.; Wong, K. S.; Zhou, Q. F.; Zhou, D.; Li, Y. C.; Luo, H. S.; Shung, K. K.; Dai, J. Y.

    2009-01-01

    Lead magnesium niobate–lead titanate single crystal 0.72Pb(Mg1∕3Nb2∕3)O3−0.28PbTiO3 (abbreviated as PMN-PT) was used to fabricate high performance ultrasonic phased-array transducer as it exhibited excellent piezoelectric properties. In this paper, we focus on the design and fabrication of a low-loss and wide-band transducer for medical imaging applications. A KLM model based simulation software PiezoCAD was used for acoustic design of the transducer including the front-face matching and backing. The calculated results show that the −6 dB transducer bandwidth can be improved significantly by using double λ∕8 matching layers and hard backing. A 4.0 MHz PMN-PT transducer array (with 16 elements) was fabricated and tested in a pulse-echo arrangement. A −6 dB bandwidth of 110% and two-way insertion loss of −46.5 dB were achieved. PMID:19657405

  16. A solid-state phase-insensitive ultrasonic transducer

    NASA Technical Reports Server (NTRS)

    Heyman, J. S.

    1979-01-01

    Photoconductive acoustoelectric transducer (AET) functions as phase-insensitive ultrasonic transducer. Device is easy to use and requires no additional noisy components such as light or thermal source.

  17. TRANSDUCER GENERATED ARRAYS OF ROBOTIC NANO-ARMS.

    PubMed

    Dolzhenko, Egor; Jonoska, Nataša; Seeman, Nadrian C

    2010-06-01

    We consider sets of two-dimensional arrays, called here transducer generated languages, obtained by iterative applications of transducers (finite state automata with output). Each transducer generates a set of blocks of symbols such that the bottom row of a block is an input string accepted by the transducer and, by iterative application of the transducer, each row of the block is an output of the transducer on the preceding row. We show how these arrays can be implemented through molecular assembly of triple crossover DNA molecules. Such assembly could serve as a scaffold for arranging molecular robotic arms capable for simultaneous movements. We observe that transducer generated languages define a class of languages which is a proper subclass of recognizable picture languages, but it containing the class of all factorial local two-dimensional languages. By taking the average growth rate of the number of blocks in the language as a measure of its complexity, we further observe that arrays with high complexity patterns can be generated in this way. PMID:24653669

  18. Real-time, 3-D ultrasound with multiple transducer arrays.

    PubMed

    Fronheiser, Matthew P; Light, Edward D; Idriss, Salim F; Wolf, Patrick D; Smith, Stephen W

    2006-01-01

    Modifications were made to a commercial real-time, three-dimensional (3-D) ultrasound system for near simultaneous 3-D scanning with two matrix array transducers. As a first illustration, a transducer cable assembly was modified to incorporate two independent, 3-D intra-cardiac echo catheters, a 7 Fr (2.3 mm O.D.) side scanning catheter and a 14 Fr (4.7 mm O.D) forward viewing catheter with accessory port, each catheter using 85 channels operating at 5 MHz. For applications in treatment of atrial fibrillation, the goal is to place the sideviewing catheter within the coronary sinus to view the whole left atrium, including a pulmonary vein. Meanwhile, the forward-viewing catheter inserted within the left atrium is directed toward the ostium of a pulmonary vein for therapy using the integrated accessory port. Using preloaded, phasing data, the scanner switches between catheters automatically, at the push of a button, with a delay of about 1 second, so that the clinician can view the therapy catheter with the coronary sinus catheter and vice versa. Preliminary imaging studies in a tissue phantom and in vivo show that our system successfully guided the forward-viewing catheter toward a target while being imaged with the sideviewing catheter. The forward-viewing catheter then was activated to monitor the target while we mimicked therapy delivery. In the future, the system will switch between 3-D probes on a line-by-line basis and display both volumes simultaneously. PMID:16471436

  19. Phased Array Ultrasonic Inspection of Titanium Forgings

    SciTech Connect

    Howard, P.; Klaassen, R.; Kurkcu, N.; Barshinger, J.; Chalek, C.; Nieters, E.; Sun, Zongqi; Fromont, F. de

    2007-03-21

    Aerospace forging inspections typically use multiple, subsurface-focused sound beams in combination with digital C-scan image acquisition and display. Traditionally, forging inspections have been implemented using multiple single element, fixed focused transducers. Recent advances in phased array technology have made it possible to perform an equivalent inspection using a single phased array transducer. General Electric has developed a system to perform titanium forging inspection based on medical phased array technology and advanced image processing techniques. The components of that system and system performance for titanium inspection will be discussed.

  20. Design and fabrication of a 40-MHz annular array transducer

    PubMed Central

    Ketterling, Jeffrey A.; Lizzi, Frederic L.; Aristizábal, Orlando; Turnbull, Daniel H.

    2006-01-01

    This paper investigates the feasibility of fabricating a 5-ring, focused annular array transducer operating at 40 MHz. The active piezoelectric material of the transducer was a 9-μm thick polyvinylidene fluoride (PVDF) film. One side of the PVDF was metallized with gold and forms the ground plane of the transducer. The array pattern of the transducer and electrical traces to each annulus were formed on a copper-clad polyimide film. The PVDF and polyimide were bonded with a thin layer of epoxy, pressed into a spherically curved shape, and then back filled with epoxy. A 5-ring transducer with equal area elements and 100 μm kerfs between annuli was fabricated and tested. The transducer had a total aperture of 6 mm and a geometric focus of 12 mm. The pulse/echo response from a quartz plate located at the geometric focus, two-way insertion loss (IL), complex impedance, electrical cross-talk, and lateral beamwidth were all measured for each annulus. The complex impedance data from each element were used to perform electrical matching and the measurements were repeated. After impedance matching, fc ≈ 36 MHz and BWs ranged from 31 to 39%. The ILs for the matched annuli ranged from −28 to −38 dB. PMID:16060516

  1. Capacitive micromachined ultrasonic transducer arrays as tunable acoustic metamaterials

    SciTech Connect

    Lani, Shane W. E-mail: karim.sabra@me.gatech.edu Sabra, Karim G.; Wasequr Rashid, M.; Hasler, Jennifer; Levent Degertekin, F.

    2014-02-03

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) operating in immersion support dispersive evanescent waves due to the subwavelength periodic structure of electrostatically actuated membranes in the array. Evanescent wave characteristics also depend on the membrane resonance which is modified by the externally applied bias voltage, offering a mechanism to tune the CMUT array as an acoustic metamaterial. The dispersion and tunability characteristics are examined using a computationally efficient, mutual radiation impedance based approach to model a finite-size array and realistic parameters of variation. The simulations are verified, and tunability is demonstrated by experiments on a linear CMUT array operating in 2-12 MHz range.

  2. Fast photo-acoustic imaging based on multi-element linear transducer array

    NASA Astrophysics Data System (ADS)

    Yin, Bangzheng; Xing, Da; Yang, Diwu; Tan, Yi; Chen, Qun

    2005-04-01

    Photoacoustic imaging combines the contrast advantage of pure optical imaging and the resolution advantage of pure ultrasonic imaging. It has become a popular research subject at present. A fast photoacoustic imaging system based on multi-element linear transducer array and phase-controlled focus method was developed and tested on phantoms and tissues. A Q switched Nd:YAG laser operating at 532nm was used in our experiment as thermal source. The multi-element linear transducer array consists of 320 elements. By phase-controlled focus method, 64 signals, one of which gathered by 11-group element, make up of an image. Experiment results can map the distribution of the optical absorption correctly. The same transducer array also can operate as a conventional phase array and produced ultrasound imaging. Compared to other existing technology and algorithm, the PA imaging based on transducer array was characterize by speediness and convenience. It can provide a new approach for tissue functional imaging in vivo, and may have potentials in developing into an appliance for clinic diagnosis.

  3. Optimization of transmitting beam patterns of a conformal transducer array.

    PubMed

    He, Zhengyao; Ma, Yuanliang

    2008-05-01

    A method is presented to calculate the driving-voltage weighting vector of a conformal array of underwater acoustic transmitting transducers to obtain a low-sidelobe beam pattern based on the measured receiving array manifold. The relationship among three quantities is given, which are, respectively, the radiated acoustic field, the measured receiving array manifold matrix and the driving-voltage weighting vector of the transducer array. Then, the driving-voltage weighting vector of the array is calculated using the optimization method to obtain a low-sidelobe transmitting beam pattern. At the frequency of 12.5 kHz, the receiving array manifold matrix of a 27-element conformal array is measured in an anechoic water tank. The driving-voltage weighting vector of the array is calculated using the proposed method. In addition, the computer simulation and experiments are carried out. The results agree well and show that the proposed method can obtain a low-sidelobe transmitting beam pattern and at the same time provide the largest amplitude of pressure in the axial direction when the maximum amplitude of the driving voltages of the array elements keeps unchanged. PMID:18529175

  4. Real-time photoacoustic imaging based on multielement linear transducer array

    NASA Astrophysics Data System (ADS)

    Yin, Bangzheng; Xing, Da; Wang, Yi; Zeng, Yaguang; Tan, Yi

    2005-01-01

    A real-time photoacoustic (PA) imaging system based on multi-element linear transducer array was developed and test on phantoms. A Q switched Nd:YAG laser operating at 532 nm and 20Hz repeat rate was used in our experiment as thermal source. The multi-element linear transducer array consists of 320 elements. By phase-controlled method, 64 signals, one of which gathered by 11-group element, make up of an image. It was acquired in only about 3 seconds. Phantom experiment results can map the distribution of the optical absorption correctly. Compared to other existing technology and algorithm, the PA imaging based on transducer array was characterize by speediness and convenience. It can provide a new approach for tissue functional imaging in vivo, and may have potentials in developing into an appliance for clinic diagnosis.

  5. Ultrasonic array of thick film transducers for biological tissue characterization.

    PubMed

    Gwirc, Sergio N; Negreira, Carlos A; Marino, Nestor R

    2010-01-01

    The initial motivation for this work was to accomplish an easy way to manufacture different geometries of ultrasonic transducers and arrays using a PZT powder, combined with a standard process to have repetitive series of them. The piezoelectric thick film was obtained using a PZT paste and applying it by screen printing on an alumina substrate. Then, the film was drying and sintered with a temperature-time profile determined by the paste characteristics. Each transducer is composed by three layers, one by PZT and two acting as electrodes. The active element of the paste is a PZT powder which is dispersed in a commercial vehicle to obtain rheological properties suitable for use the screen printing process. The connection between PZT particles is improved by adding a lead borosilicate frit glass that also helps to attach the film to the substrate due to the relatively low temperature of sintered that has been used in this process. The PZT film has low density that is generated by internal porosity, so its acoustic impedance is lower than for a bulk ceramic transducer and so is well adapted to testing human tissues. At the same time the thick film technology is well suited to make medium size transducers and also arrays performed with tiny ultrasonic transducers. PMID:21097177

  6. Breast ultrasound tomography with two parallel transducer arrays

    NASA Astrophysics Data System (ADS)

    Huang, Lianjie; Shin, Junseob; Chen, Ting; Lin, Youzuo; Gao, Kai; Intrator, Miranda; Hanson, Kenneth

    2016-03-01

    Breast ultrasound tomography is an emerging imaging modality to reconstruct the sound speed, density, and ultrasound attenuation of the breast in addition to ultrasound reflection/beamforming images for breast cancer detection and characterization. We recently designed and manufactured a new synthetic-aperture breast ultrasound tomography prototype with two parallel transducer arrays consisting of a total of 768 transducer elements. The transducer arrays are translated vertically to scan the breast in a warm water tank from the chest wall/axillary region to the nipple region to acquire ultrasound transmission and reflection data for whole-breast ultrasound tomography imaging. The distance of these two ultrasound transducer arrays is adjustable for scanning breasts with different sizes. We use our breast ultrasound tomography prototype to acquire phantom and in vivo patient ultrasound data to study its feasibility for breast imaging. We apply our recently developed ultrasound imaging and tomography algorithms to ultrasound data acquired using our breast ultrasound tomography system. Our in vivo patient imaging results demonstrate that our breast ultrasound tomography can detect breast lesions shown on clinical ultrasound and mammographic images.

  7. A low-frequency directional flextensional transducer and line array

    SciTech Connect

    Butler, S.C.; Butler, J.L.; Butler, A.L.; Cavanagh, G.H.

    1997-07-01

    A unique low-frequency (900 Hz) class IV flextensional transducer that produces an enhanced far-field pressure on one side and canceled far-field pressure on the other side has been developed. The transducer radiating surface consists of a thick-walled elliptical aluminum shell and a U.S. Navy type III piezoelectric stack along its major axis with two active sections and one inactive section. The directionality is achieved by simultaneously exciting the shell into an omnidirectional and dipole operation by driving stack into both extensional and bending modes. Both measurements and modeling on this device show a front to back pressure ratio of more than 30 dB, producing cardioid-type radiation patterns over an octave band, for a single transducer element. The transducers measured mechanical Q is 8, coupling coefficient is 0.25, and electroacoustic efficiency is 80{percent} and produced a source level of 215 dB {ital re:} 1 {mu}Pa at 1 m when driven at a field limit of 394 kV/m (10 kV/in.) at resonance. The uniqueness of this transducer is its directional beam patterns (directivity index=3.4 dB) and high acoustic output power from a small (less than a third of a wavelength) single element. Six of these transducers were placed in a closely packed line array two-wavelengths long. The array successfully produced narrow directional sound beams (directivity index=8.7 dB) with a front to back ratio greater than 30 dB and a source level of 225 dB {ital re:} 1 {mu}Pa at 1 m. {copyright} {ital 1997 Acoustical Society of America.}

  8. Arrayed Ultrasonic Transducers on Arc Surface for Plane Wave Synthesis

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Soon; Kim, Jung-Ho; Kim, Moo-Joon; Ha, Kang-Lyeol; Yamada, Akira

    2004-05-01

    In ultrasonic computed tomography (UCT), it is necessary to synthesize a plane wave using waves emitted from sound sources arranged in the interior surface of a cylinder. In order to transmit a plane wave into a cylindrical surface, an ultrasonic transducer which has many vibrating elements with piezoelectric transverse effect arrayed on an arc surface is proposed. To achieve a wide beam width, the elements should have a small radiation area with a much narrow width. The measured electroacoustic efficiency for the elements was approximately 40% and the beam width defined by -3 dB level from the maximum was as wide as 120 deg. It was confirmed that plane wave synthesis is possible using the proposed transducer array.

  9. A Low Frequency Broadband Flextensional Ultrasonic Transducer Array.

    PubMed

    Savoia, Alessandro Stuart; Mauti, Barbara; Caliano, Giosuè

    2016-01-01

    In this paper, we propose the design and the fabrication of a multicell, piezoelectrically actuated, flextensional transducer array structure, characterized by a low mechanical impedance, thus allowing wideband and high-sensitivity immersion operation in the low ultrasonic frequency range. The transducer structure, consisting of a plurality of circular elementary cells orderly arranged according to a periodic hexagonal tiling, features a high flexibility in the definition of the active area shape and size. We investigate, by finite element modeling (FEM), the influence of different piezoelectric and elastic materials for the flexural plate, for the plate support and for the backing, on the transducer electroacoustic behavior. We carry out the dimensioning of the transducer components and cell layout, in terms of materials and geometry, respectively, by aiming at a circular active area of 80-mm diameter and broadband operation in the 30-100-kHz frequency range in immersion. PZT-5H ceramic disks and a calibrated thickness stainless steel plate are chosen for the vibrating structure, and FR-4 laminates and a brass plate, respectively, for the plate support and the backing. The diameter of the individual cells is set to 6 mm resulting in 121 cells describing a quasi-circular area, and the total thickness of the transducer is less than 10 mm. We report on the fabrication process flow for the accurate assembly of the transducer, based, respectively, on epoxy resin and wire bonding for the mechanical and electrical interconnection of the individual parts. The results of the electrical impedance and transmit pressure field characterization are finally reported and discussed. PMID:26540680

  10. Photoacoustic Imaging of Animals with an Annular Transducer Array

    NASA Astrophysics Data System (ADS)

    Yang, Di-Wu; Zhou, Zhi-Bin; Zeng, Lv-Ming; Zhou, Xin; Chen, Xing-Hui

    2014-07-01

    A photoacoustic system with an annular transducer array is presented for rapid, high-resolution photoacoustic tomography of animals. An eight-channel data acquisition system is applied to capture the photoacoustic signals by using multiplexing and the total time of data acquisition and transferring is within 3 s. A limited-view filtered back projection algorithm is used to reconstruct the photoacoustic images. Experiments are performed on a mouse head and a rabbit head and clear photoacoustic images are obtained. The experimental results demonstrate that this imaging system holds the potential for imaging the human brain.

  11. The NMR phased array.

    PubMed

    Roemer, P B; Edelstein, W A; Hayes, C E; Souza, S P; Mueller, O M

    1990-11-01

    We describe methods for simultaneously acquiring and subsequently combining data from a multitude of closely positioned NMR receiving coils. The approach is conceptually similar to phased array radar and ultrasound and hence we call our techniques the "NMR phased array." The NMR phased array offers the signal-to-noise ratio (SNR) and resolution of a small surface coil over fields-of-view (FOV) normally associated with body imaging with no increase in imaging time. The NMR phased array can be applied to both imaging and spectroscopy for all pulse sequences. The problematic interactions among nearby surface coils is eliminated (a) by overlapping adjacent coils to give zero mutual inductance, hence zero interaction, and (b) by attaching low input impedance preamplifiers to all coils, thus eliminating interference among next nearest and more distant neighbors. We derive an algorithm for combining the data from the phased array elements to yield an image with optimum SNR. Other techniques which are easier to implement at the cost of lower SNR are explored. Phased array imaging is demonstrated with high resolution (512 x 512, 48-cm FOV, and 32-cm FOV) spin-echo images of the thoracic and lumbar spine. Data were acquired from four-element linear spine arrays, the first made of 12-cm square coils and the second made of 8-cm square coils. When compared with images from a single 15 x 30-cm rectangular coil and identical imaging parameters, the phased array yields a 2X and 3X higher SNR at the depth of the spine (approximately 7 cm). PMID:2266841

  12. FEL phased array configurations

    NASA Astrophysics Data System (ADS)

    Shellan, Jeffrey B.

    1986-01-01

    The advantages and disadvantages of various phased array and shared aperture concepts for FEL configurations are discussed. Consideration is given to the characteristics of intra- and inter-micropulse phasing; intra-macropulse phasing; an internal coupled resonator configuration; and an injection locked oscillator array. The use of a master oscillator power amplifier (MOPA) configuration with multiple or single master oscillators for FELs is examined. The venetian blind, rotating plate, single grating, and grating rhomb shared aperture concepts are analyzed. It is noted that the shared aperture approach using a grating rhomb and the MOPA concept with a single master oscillator and a coupled resonator are useful for FEL phased array configurations; and the MOPA concept is most applicable.

  13. Coaxial phased array antenna

    NASA Astrophysics Data System (ADS)

    Ellis, H., Jr.

    1980-08-01

    A coaxial antenna array for communicating circularly polarized electromagnetic radiation is disclosed. A pair of open ended antenna cavities is coaxially constructed and operates by excitation of linear radiation elements arranged within each of the cavities. A pair of crossed dipole radiation devices is centered within the inner cavity and operated by means of a phase shifting network circuit to transmit as well as receive circularly polarized radiation. Four monopole radiation devices are symmetrically arranged to operate in the outer cavity in phase quadrature by means of the phase shifting network circuit to both transmit and receive circularly polarized electromagnetic radiation. Combined operation of the two antenna cavities with a 180 deg phase differential between the fields related to the two antenna cavities provides a broad beam, relatively wide frequency bandwidth communication capability. Particular embodiments disclosed feature a generally square cavity array as well as a circular cavity array.

  14. Coaxial phased array antenna

    NASA Technical Reports Server (NTRS)

    Ellis, H., Jr. (Inventor)

    1980-01-01

    A coaxial antenna array for communicating circularly polarized electromagnetic radiation is disclosed. A pair of open ended antenna cavities is coaxially constructed and operates by excitation of linear radiation elements arranged within each of the cavities. A pair of crossed dipole radiation devices is centered within the inner cavity and operated by means of a phase shifting network circuit to transmit as well as receive circularly polarized radiation. Four monopole radiation devices are symmetrically arranged to operate in the outer cavity in phase quadrature by means of the phase shifting network circuit to both transmit and receive circularly polarized electromagnetic radiation. Combined operation of the two antenna cavities with a 180 deg phase differential between the fields related to the two antenna cavities provides a broad beam, relatively wide frequency bandwidth communication capability. Particular embodiments disclosed feature a generally square cavity array as well as a circular cavity array.

  15. Multibeam Phased Array Antennas

    NASA Technical Reports Server (NTRS)

    Popovic, Zoya; Romisch, Stefania; Rondineau, Sebastien

    2004-01-01

    In this study, a new architecture for Ka-band multi-beam arrays was developed and demonstrated experimentally. The goal of the investigation was to demonstrate a new architecture that has the potential of reducing the cost as compared to standard expensive phased array technology. The goals of this specific part of the project, as stated in the yearly statement of work in the original proposal are: 1. Investigate bounds on performance of multi-beam lens arrays in terms of beamwidths, volume (size), isolation between beams, number of simultaneous beams, etc. 2. Design a small-scale array to demonstrate the principle. The array will be designed for operation around 3OGHz (Ka-band), with two 10-degree beamwidth beams. 3. Investigate most appropriate way to accomplish fine-tuning of the beam pointing within 5 degrees around the main beam pointing angle.

  16. Volumetric Security Alarm Based on a Spherical Ultrasonic Transducer Array

    NASA Astrophysics Data System (ADS)

    Sayin, Umut; Scaini, Davide; Arteaga, Daniel

    Most of the existent alarm systems depend on physical or visual contact. The detection area is often limited depending on the type of the transducer, creating blind spots. Our proposition is a truly volumetric alarm system that can detect any movement in the intrusion area, based on monitoring the change over time of the impulse response of the room, which acts as an acoustic footprint. The device depends on an omnidirectional ultrasonic transducer array emitting sweep signals to calculate the impulse response in short intervals. Any change in the room conditions is monitored through a correlation function. The sensitivity of the alarm to different objects and different environments depends on the sweep duration, sweep bandwidth, and sweep interval. Successful detection of intrusions also depends on the size of the monitoring area and requires an adjustment of emitted ultrasound power. Strong air flow affects the performance of the alarm. A method for separating moving objects from strong air flow is devised using an adaptive thresholding on the correlation function involving a series of impulse response measurements. The alarm system can be also used for fire detection since air flow sourced from heating objects differ from random nature of the present air flow. Several measurements are made to test the integrity of the alarm in rooms sizing from 834-2080m3 with irregular geometries and various objects. The proposed system can efficiently detect intrusion whilst adequate emitting power is provided.

  17. Visualization and simulation of a linear explosive-induced pyroshock wave using Q-switched laser and phased array transducers in a space launcher composite structure

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Ryul; Jang, Jae-Kyeong; Choi, Mijin; Kong, Cheol-Won

    2015-04-01

    During space flights, pyrotechnic devices are used for various purposes such as separation of boosters, satellites, fairings, and stages. In particular, the prediction of high shock structural response induced by linear explosives is important for safe operation of pyrotechnic devices. In general, repetitive explosive testing using distributed accelerometers is widely used, but multiple test structures are usually necessary because they are easily damaged and not reusable. This paper pertains to a nondestructive technology to replace the damage-causing, time-consuming, expensive, dangerous, and low-repeatability explosive test with a laser-induced shock test. The method proposed in this paper predicts nondestructively the linear explosive-induced pyroshock wave, visualizes its propagation, and allows the simulation of some detonation conditions. A ballistic test based on a linear explosive and noncontact laser Doppler vibrometer (LDV) as well as a nondestructive pyroshock test using laser-induced shock and PZT array sensors is performed in a 12.68-mm thick composite sandwich panel. The optimal laser-induced shock experimental conditions to predict real pyroshock response spectra (SRSs) are investigated by controlling the optical characteristics of the laser beam and adjusting the frequency bands in signal acquisition. The similarity of the SRS of the conditioned laser-induced shock to that of the real explosive pyroshock is evaluated with the mean acceleration difference. Next, the experimentally-determined optimal conditions are applied to arbitrary points in the laser-induced shock scanning area. Finally, it is shown that the proposed method will allow nondestructive and quantitative pyroshock testing, pyroshock wave propagation visualization showing the direction and magnitude of principal wave propagation, and detonation speed simulation depending on explosive type and detonation initiation point and direction.

  18. Phased array antenna control

    NASA Technical Reports Server (NTRS)

    Doland, G. D. (Inventor)

    1978-01-01

    Several new and useful improvements in steering and control of phased array antennas having a small number of elements, typically on the order of 5 to 17 elements are provided. Among the improvements are increasing the number of beam steering positions, reducing the possibility of phase transients in signals received or transmitted with the antennas, and increasing control and testing capacity with respect to the antennas.

  19. Semiconductor Laser Phased Array

    NASA Technical Reports Server (NTRS)

    Katz, J.

    1985-01-01

    Oscillations synchronized and modulated individually for beam steering. Phased array of GaAs infrared lasers put out powerful electronically-steerable coherent beam. Fabricated as integrated circuit on GaAs chip, new device particularly suited to optical communications, optical data processing and optical detection and ranging systems.

  20. Experimental Study on Ultrasonic Computed Tomography Using Transducers Arrayed on the Internal Surface of a Cylinder

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Soon; Kim, Moo-Joon; Kim, Jung-Ho; Ha, Kang-Lyeol

    2005-06-01

    In this study, ultrasonic array transducers with 32 vibrators arranged on the internal surface of a part of a cylinder were fabricated. The vibrators were operated by the piezoelectric transverse effect. By controlling the phase of the input signal for every vibrator, a quasi plane wave was synthesized. Using the fabricated array, inverse scattering ultrasonic computed tomography (UCT) was carried out with a phantom specimen after checking the plane wave generation. It was confirmed that the plane wave was synthesized successfully and a sound velocity image of the phantom was obtained by the plane wave. Consequently, it was noted that the array could be employed as a transmitter and receiver for data acquisition in UCT.

  1. Acoustic trapping with a high frequency linear phased array

    NASA Astrophysics Data System (ADS)

    Zheng, Fan; Li, Ying; Hsu, Hsiu-Sheng; Liu, Changgeng; Tat Chiu, Chi; Lee, Changyang; Ham Kim, Hyung; Shung, K. Kirk

    2012-11-01

    A high frequency ultrasonic phased array is shown to be capable of trapping and translating microparticles precisely and efficiently, made possible due to the fact that the acoustic beam produced by a phased array can be both focused and steered. Acoustic manipulation of microparticles by a phased array is advantageous over a single element transducer since there is no mechanical movement required for the array. Experimental results show that 45 μm diameter polystyrene microspheres can be easily and accurately trapped and moved to desired positions by a 64-element 26 MHz phased array.

  2. A comparison of methods for focusing the field of a HIFU array transducer through human ribs

    NASA Astrophysics Data System (ADS)

    Gélat, P.; ter Haar, G.; Saffari, N.

    2014-06-01

    A forward model, which predicts the scattering by human ribs of a multi-element high-intensity focused ultrasound transducer, was used to investigate the efficacy of a range of focusing approaches described in the literature. This forward model is based on the boundary element method and was described by Gélat et al (2011 Phys. Med. Biol. 56 5553-81 2012 Phys. Med. Biol. 57 8471-97). The model has since been improved and features a complex surface impedance condition at the surface of the ribs. The inverse problem of focusing through the ribs was implemented on six transducer array-rib topologies and five methods of focusing were investigated, including spherical focusing, binarized apodization based on geometric ray tracing, phase conjugation and the decomposition of the time-reversal operator method. The excitation frequency was 1 MHz and the array was of spherical-section type. Both human and idealized rib topologies were considered. The merit of each method of focusing was examined. It was concluded that the constrained optimization approach offers greater potential than the other focusing methods in terms of maximizing the ratio of acoustic pressure magnitudes at the focus to those on the surface of the ribs whilst taking full advantage of the dynamic range of the phased array.

  3. Phased array ghost elimination.

    PubMed

    Kellman, Peter; McVeigh, Elliot R

    2006-05-01

    Parallel imaging may be applied to cancel ghosts caused by a variety of distortion mechanisms, including distortions such as off-resonance or local flow, which are space variant. Phased array combining coefficients may be calculated that null ghost artifacts at known locations based on a constrained optimization, which optimizes SNR subject to the nulling constraint. The resultant phased array ghost elimination (PAGE) technique is similar to the method known as sensitivity encoding (SENSE) used for accelerated imaging; however, in this formulation is applied to full field-of-view (FOV) images. The phased array method for ghost elimination may result in greater flexibility in designing acquisition strategies. For example, in multi-shot EPI applications ghosts are typically mitigated by the use of an interleaved phase encode acquisition order. An alternative strategy is to use a sequential, non-interleaved phase encode order and cancel the resultant ghosts using PAGE parallel imaging. Cancellation of ghosts by means of phased array processing makes sequential, non-interleaved phase encode acquisition order practical, and permits a reduction in repetition time, TR, by eliminating the need for echo-shifting. Sequential, non-interleaved phase encode order has benefits of reduced distortion due to off-resonance, in-plane flow and EPI delay misalignment. Furthermore, the use of EPI with PAGE has inherent fat-water separation and has been used to provide off-resonance correction using a technique referred to as lipid elimination with an echo-shifting N/2-ghost acquisition (LEENA), and may further generalized using the multi-point Dixon method. Other applications of PAGE include cancelling ghosts which arise due to amplitude or phase variation during the approach to steady state. Parallel imaging requires estimates of the complex coil sensitivities. In vivo estimates may be derived by temporally varying the phase encode ordering to obtain a full k-space dataset in a scheme

  4. An ultrasonic transducer array for velocity measurement in underwater vehicles.

    PubMed

    Boltryk, P; Hill, M; Keary, A; Phillips, B; Robinson, H; White, P

    2004-04-01

    A correlation velocity log (CVL) is an ultrasonic navigation aid for marine applications, in which velocity is estimated using an acoustic transmitter and a receiver array. CVLs offer advantages over Doppler velocity logs (DVLs) in many autonomous underwater vehicle (AUV) applications, since they can achieve high accuracy at low velocities even during hover manoeuvres. DVLs require narrow beam widths, whilst ideal CVL transmitters have wide beam widths. This gives CVLs the potential to use lower frequencies thus permitting operation in deeper water, reducing power requirements for the same depth, or allowing the use of smaller transducers. Moving patterns in the wavefronts across a 2D receiver array are detected by calculating correlation coefficients between bottom reflections from consecutive transmitted pulses, across all combinations of receiver pairings. The position of the peak correlation value, on a surface representing receiver-pairing separations, is proportional to the vessel's displacement between pulses. A CVL aimed primarily for AUVs has been developed. Its acoustical and signal processing design has been optimised through sea trials and computer modelling of the sound field. This computer model is also used to predict how the distribution of the correlation coefficients varies with distance from the peak position. Current work seeks to increase the resolution of the peak estimate using surface fitting methods. Numerical simulations suggest that peak estimation methods significantly improve system precision when compared with simply identifying the position of the maximum correlation coefficient in the dataset. The peak position may be estimated by fitting a quadratic model to the measured data using least squares or maximum likelihood estimation. Alternatively, radial basis functions and Gaussian processes successfully predict the peak position despite variation between individual correlation datasets. This paper summarises the CVL's main acoustical

  5. Optically interconnected phased arrays

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul B.; Kunath, Richard R.

    1988-01-01

    Phased-array antennas are required for many future NASA missions. They will provide agile electronic beam forming for communications and tracking in the range of 1 to 100 GHz. Such phased arrays are expected to use several hundred GaAs monolithic integrated circuits (MMICs) as transmitting and receiving elements. However, the interconnections of these elements by conventional coaxial cables and waveguides add weight, reduce flexibility, and increase electrical interference. Alternative interconnections based on optical fibers, optical processing, and holography are under evaluation as possible solutions. In this paper, the current status of these techniques is described. Since high-frequency optical components such as photodetectors, lasers, and modulators are key elements in these interconnections, their performance and limitations are discussed.

  6. Phased array performance evaluation with photoelastic visualization

    SciTech Connect

    Ginzel, Robert; Dao, Gavin

    2014-02-18

    New instrumentation and a widening range of phased array transducer options are affording the industry a greater potential. Visualization of the complex wave components using the photoelastic system can greatly enhance understanding of the generated signals. Diffraction, mode conversion and wave front interaction, together with beam forming for linear, sectorial and matrix arrays, will be viewed using the photoelastic system. Beam focus and steering performance will be shown with a range of embedded and surface targets within glass samples. This paper will present principles and sound field images using this visualization system.

  7. Applications of Flexible Ultrasonic Transducer Array for Defect Detection at 150 °C

    PubMed Central

    Shih, Jeanne-Louise; Wu, Kuo-Ting; Jen, Cheng-Kuei; Chiu, Chun-Hsiung; Tzeng, Jing-Chi; Liaw, Jiunn-Woei

    2013-01-01

    In this study, the feasibility of using a one dimensional 16-element flexible ultrasonic transducer (FUT) array for nondestructive testing at 150 °C is demonstrated. The FUT arrays were made by a sol-gel sprayed piezoelectric film technology; a PZT composite film was sprayed on a titanium foil of 75 μm thickness. Since the FUT array is flexible, it was attached to a steel pipe with an outer diameter of 89 mm and a wall thickness of 6.5 mm at 150 °C. Using the ultrasonic pulse-echo mode, pipe thickness measurements could be performed. Moreover, using the ultrasonic pulse-echo and pitch-catch modes of each element of FUT array, the defect detection was performed on an Al alloy block of 30 mm thickness with a side-drilled hole (SDH) of ϕ3 mm at 150 °C. In addition, a post-processing algorithm based on the total focusing method was used to process the full matrix of these A-scan signals of each single transmitter and multi-receivers, and then the phase-array image was obtained to indicate this defect- SDH. Both results show the capability of FUT array being operated at 150 °C for the corrosion and defect detections. PMID:23322101

  8. Applications of flexible ultrasonic transducer array for defect detection at 150 °C.

    PubMed

    Shih, Jeanne-Louise; Wu, Kuo-Ting; Jen, Cheng-Kuei; Chiu, Chun-Hsiung; Tzeng, Jing-Chi; Liaw, Jiunn-Woei

    2013-01-01

    In this study, the feasibility of using a one dimensional 16-element flexible ultrasonic transducer (FUT) array for nondestructive testing at 150 °C is demonstrated. The FUT arrays were made by a sol-gel sprayed piezoelectric film technology; a PZT composite film was sprayed on a titanium foil of 75 µm thickness. Since the FUT array is flexible, it was attached to a steel pipe with an outer diameter of 89 mm and a wall thickness of 6.5 mm at 150 °C. Using the ultrasonic pulse-echo mode, pipe thickness measurements could be performed. Moreover, using the ultrasonic pulse-echo and pitch-catch modes of each element of FUT array, the defect detection was performed on an Al alloy block of 30 mm thickness with a side-drilled hole (SDH) of f3 mm at 150 °C. In addition, a post-processing algorithm based on the total focusing method was used to process the full matrix of these A-scan signals of each single transmitter and multi-receivers, and then the phase-array image was obtained to indicate this defect- SDH. Both results show the capability of FUT array being operated at 150 °C for the corrosion and defect detections. PMID:23322101

  9. Intracavitary ultrasound phased arrays for thermal therapies

    NASA Astrophysics Data System (ADS)

    Hutchinson, Erin

    Currently, the success of hyperthermia and thermal surgery treatments is limited by the technology used in the design and fabrication of clinical heating devices and the completeness of the thermometry systems used for guidance. For both hyperthermia and thermal surgery, electrically focused ultrasound generated by phased arrays provides a means of controlling localized energy deposition in body tissues. Intracavitary applicators can be used to bring the energy source close to a target volume, such as the prostate, thereby minimizing normal tissue damage. The work performed in this study was aimed at improving noninvasive prostate thermal therapies and utilized three research approaches: (1) Acoustic, thermal and optimization simulations, (2) Design and fabrication of multiple phased arrays, (3) Ex vivo and in vivo experimental testing of the heating capabilities of the phased arrays. As part of this study, a novel aperiodic phased array design was developed which resulted in a 30- 45% reduction in grating lobe levels when compared to conventional phased arrays. Measured acoustic fields generated by the constructed aperiodic arrays agreed closely with the fields predicted by the theoretical simulations and covered anatomically appropriate ranges. The power capabilities of these arrays were demonstrated to be sufficient for the purposes of hyperthermia and thermal surgery. The advantage of using phased arrays in place of fixed focus transducers was shown by demonstrating the ability of electronic scanning to increase the size of the necrosed tissue volume while providing a more uniform thermal dose, which can ultimately reduce patient treatment times. A theoretical study on the feasibility of MRI (magnetic resonance imaging) thermometry for noninvasive temperature feedback control was investigated as a means to improve transient and steady state temperature distributions achieved in hyperthermia treatments. MRI guided ex vivo and in vivo experiments demonstrated

  10. Breast ultrasound tomography with two parallel transducer arrays: preliminary clinical results

    NASA Astrophysics Data System (ADS)

    Huang, Lianjie; Shin, Junseob; Chen, Ting; Lin, Youzuo; Intrator, Miranda; Hanson, Kenneth; Epstein, Katherine; Sandoval, Daniel; Williamson, Michael

    2015-03-01

    Ultrasound tomography has great potential to provide quantitative estimations of physical properties of breast tumors for accurate characterization of breast cancer. We design and manufacture a new synthetic-aperture breast ultrasound tomography system with two parallel transducer arrays. The distance of these two transducer arrays is adjustable for scanning breasts with different sizes. The ultrasound transducer arrays are translated vertically to scan the entire breast slice by slice and acquires ultrasound transmission and reflection data for whole-breast ultrasound imaging and tomographic reconstructions. We use the system to acquire patient data at the University of New Mexico Hospital for clinical studies. We present some preliminary imaging results of in vivo patient ultrasound data. Our preliminary clinical imaging results show promising of our breast ultrasound tomography system with two parallel transducer arrays for breast cancer imaging and characterization.

  11. Nonlinear phased array imaging

    NASA Astrophysics Data System (ADS)

    Croxford, Anthony J.; Cheng, Jingwei; Potter, Jack N.

    2016-04-01

    A technique is presented for imaging acoustic nonlinearity within a specimen using ultrasonic phased arrays. Acoustic nonlinearity is measured by evaluating the difference in energy of the transmission bandwidth within the diffuse field produced through different focusing modes. The two different modes being classical beam forming, where delays are applied to different element of a phased array to physically focus the energy at a single location (parallel firing) and focusing in post processing, whereby one element at a time is fired and a focused image produced in post processing (sequential firing). Although these two approaches are linearly equivalent the difference in physical displacement within the specimen leads to differences in nonlinear effects. These differences are localized to the areas where the amplitude is different, essentially confining the differences to the focal point. Direct measurement at the focal point are however difficult to make. In order to measure this the diffuse field is used. It is a statistical property of the diffuse field that it represents the total energy in the system. If the energy in the diffuse field for both the sequential and parallel firing case is measured then the difference between these, within the input signal bandwidth, is largely due to differences at the focal spot. This difference therefore gives a localized measurement of where energy is moving out of the transmission bandwidth due to nonlinear effects. This technique is used to image fatigue cracks and other damage types undetectable with conventional linear ultrasonic measurements.

  12. Micromachining techniques in developing high-frequency piezoelectric composite ultrasonic array transducers.

    PubMed

    Liu, Changgeng; Djuth, Frank T; Zhou, Qifa; Shung, K Kirk

    2013-12-01

    Several micromachining techniques for the fabrication of high-frequency piezoelectric composite ultrasonic array transducers are described in this paper. A variety of different techniques are used in patterning the active piezoelectric material, attaching backing material to the transducer, and assembling an electronic interconnection board for transmission and reception from the array. To establish the feasibility of the process flow, a hybrid test ultrasound array transducer consisting of a 2-D array having an 8 × 8 element pattern and a 5-element annular array was designed, fabricated, and assessed. The arrays are designed for a center frequency of ~60 MHz. The 2-D array elements are 105 × 105 μm in size with 5-μm kerfs between elements. The annular array surrounds the square 2-D array and provides the option of transmitting from the annular array and receiving with the 2-D array. Each annular array element has an area of 0.71 mm(2) with a 16-μm kerf between elements. The active piezoelectric material is (1 - x) Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT)/epoxy 1-3 composite with a PMN-PT pillar lateral dimension of 8 μm and an average gap width of ~4 μm, which was produced by deep reactive ion etching (DRIE) dry etching techniques. A novel electric interconnection strategy for high-density, small-size array elements was proposed. After assembly, the array transducer was tested and characterized. The capacitance, pulse-echo responses, and crosstalk were measured for each array element. The desired center frequency of ~60 MHz was achieved and the -6-dB bandwidth of the received signal was ~50%. At the center frequency, the crosstalk between adjacent 2-D array elements was about -33 dB. The techniques described herein can be used to build larger arrays containing smaller elements. PMID:24297027

  13. The design of a focused ultrasound transducer array for the treatment of stroke: a simulation study

    NASA Astrophysics Data System (ADS)

    Pajek, Daniel; Hynynen, Kullervo

    2012-08-01

    High intensity focused ultrasound (HIFU) is capable of mechanically disintegrating blood clots at high pressures. Safe thrombolysis may require frequencies higher than those currently utilized by transcranial HIFU. Since the attenuation and focal distortion of ultrasound in bone increases at higher frequencies, resulting focal pressures are diminished. This study investigated the feasibility of using transcranial HIFU for the non-invasive treatment of ischemic stroke. The use of large aperture, 1.1-1.5 MHz phased arrays in targeting four clinically relevant vessel locations was simulated. Resulting focal sizes decreased with frequency, producing a maximum -3 dB depth of field and lateral width of 2.0 and 1.2 mm, respectively. Mean focal gains above an order of magnitude were observed in three of four targets and transducer intensities required to achieve thrombolysis were determined. Required transducer element counts are about an order of magnitude higher than what currently exists and so, although technically feasible, new arrays would need to be developed to realize this as a treatment modality for stroke.

  14. Trends in phased array development

    NASA Astrophysics Data System (ADS)

    Schell, A. C.

    1986-03-01

    In the past 15 years, several outstanding phased arrays have been taken into service for functions involving defense applications. It is pointed out, however, that the impact of phased array technology on radar and communications antennas has been minor in comparison to the impact of solid-state technology on the other major subsystem, the signal processor. This situation is mainly related to cost considerations, and the scale of the commercial market involved. Attention is given to details regarding the economics of phased arrays, a possible key to improved solutions to phased array construction and operation, the employment of the techniques of photolithography in the fabrication of a transversely-developed array, the need for manufacturing techniques to incorporate magnetic or electroacoustic control devices into the array, problems of heat generation, small mm-wave arrays, questions of reliability, and integrated antennas.

  15. Manipulation of Liquids Using Phased Array Generation of Acoustic Radiation Pressure

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C. (Inventor)

    2000-01-01

    A phased array of piezoelectric transducers is used to control and manipulate contained as well as uncontained fluids in space and earth applications. The transducers in the phased array are individually activated while being commonly controlled to produce acoustic radiation pressure and acoustic streaming. The phased array is activated to produce a single pulse, a pulse burst or a continuous pulse to agitate, segregate or manipulate liquids and gases. The phased array generated acoustic radiation pressure is also useful in manipulating a drop, a bubble or other object immersed in a liquid. The transducers can be arranged in any number of layouts including linear single or multi- dimensional, space curved and annular arrays. The individual transducers in the array are activated by a controller, preferably driven by a computer.

  16. Transducer arrays for omnidirectional guided wave mode control in plate like structures

    NASA Astrophysics Data System (ADS)

    Koduru, Jaya P.; Rose, Joseph L.

    2013-01-01

    For structural health monitoring applications, ultrasonic guided wave mode control is critical for obtaining simple signals that can be easily analyzed as well as special modes and frequencies for improved sensitivity to certain defects. This paper discusses the development of an annular array transducer for omnidirectional guided wave mode control in plate like structures. Using a flexible piezoelectric material like polyvinlydine fluoride (PVDF), annular array transducers that are low cost, low profile and conformable to the structure can be made rapidly. Two different array patterns, namely ones of comb and inter-digital (IDT) type, are studied. The loadings of these transducers on a structure differ from one another and hence so do their source influences. An axi-symmetric finite element modeling is employed to study the surface displacement pattern of these two transducer configurations. The source influence of the transducer configurations is studied experimentally by exciting an anti-symmetric (A1) and a symmetric (S1) type guided wave mode in a steel plate. It was observed that IDT type transducers were able to couple well to the guided wave modes at the wavelengths that they are designed for. The comb type transducers have a weak coupling to symmetric guided wave modes at frequencies where the wave structure has high in-plane displacement and negligible out-of-plane displacement on the surface of the structure.

  17. Measurement of two-phase flow momentum with force transducers

    SciTech Connect

    Hardy, J.E.; Smith, J.E.

    1990-01-01

    Two strain-gage-based drag transducers were developed to measure two-phase flow in simulated pressurized water reactor (PWR) test facilities. One transducer, a drag body (DB), was designed to measure the bidirectional average momentum flux passing through an end box. The second drag sensor, a break through detector (BTD), was designed to sense liquid downflow from the upper plenum to the core region. After prototype sensors passed numerous acceptance tests, transducers were fabricated and installed in two experimental test facilities, one in Japan and one in West Germany. High-quality data were extracted from both the DBs and BTDs for a variety of loss-of-coolant accident (LOCA) scenarios. The information collected from these sensors has added to the understanding of the thermohydraulic phenomena that occur during the refill/reflood stage of a LOCA in a PWR. 9 refs., 15 figs.

  18. Equivalent Circuit Models for Large Arrays of Curved and Flat Piezoelectric Micromachined Ultrasonic Transducers.

    PubMed

    Akhbari, Sina; Sammoura, Firas; Lin, Liwei

    2016-03-01

    Equivalent circuit models of large arrays of curved (spherical shape) and flat piezoelectric micromachined ultrasonic transducers (pMUTs) have been developed for complex pMUT arrays design and analysis. The exact solutions for circuit parameters in the electromechanical domain, such as mechanical admittance, input electrical impedance, and electromechanical transformer ratio, were analytically derived. By utilizing the array solution methods previously established for the thickness-mode piezoelectric devices and capacitive micromachined ultrasonic transducers (cMUTs), the single pMUT circuit model can be extended to models for array structures. The array model includes both the self- and mutual-acoustic radiation impedances of individual transducers in the acoustic medium. Volumetric displacement, induced piezoelectric current, and pressure field can be derived with respect to the input voltage matrix, material, and geometrical properties of each individual transducer and the array structure. As such, the analytical models presented here can be used as a guideline for analyses and design evaluations of large arrays of curved and flat pMUTs efficiently and can be further generalized to evaluate other pMUT architectures in the form of single devices or arrays. PMID:26863658

  19. Damage Detection in Plate Structures Using Sparse Ultrasonic Transducer Arrays and Acoustic Wavefield Imaging

    SciTech Connect

    Michaels, T.E.; Michaels, J.E.; Mi, B.; Ruzzene, M.

    2005-04-09

    A methodology is presented for health monitoring and subsequent inspection of critical structures. Algorithms have been developed to detect and approximately locate damaged regions by analyzing signals recorded from a permanently mounted, sparse array of transducers. Followup inspections of suspected flaw locations are performed using a dual transducer ultrasonic approach where a permanently mounted transducer is the source and an externally scanned transducer is the receiver. Scan results are presented as snapshots of the propagating ultrasonic wavefield radiating out from the attached transducers. This method, referred to here as Acoustic Wavefield Imaging (AWI), provides an excellent visual representation of the interaction of propagating ultrasonic waves with the structure. Pre-flaw and post-flaw ultrasonic waveforms are analyzed from an aluminum plate specimen with artificially induced damage, and the AWI results show the location and spatial extent of all of the defects.

  20. Active membrane phased array radar

    NASA Technical Reports Server (NTRS)

    Moussessian, Alina; Del Castillo, Linda; Huang, John; Sadowy, Greg; Hoffman, James; Smith, Phil; Hatake, Toshiro; Derksen, Chuck; Lopez, Bernardo; Caro, Ed

    2005-01-01

    We have developed the first membrane-based active phased array in L-band (1.26GHz). The array uses membrane compatible Transmit/Receive (T/R) modules (membrane T/R) for each antenna element. We use phase shifters within each T/R module for electronic beam steering. We will discuss the T/R module design and integration with the membrane, We will also present transmit and receive beam-steering results for the array.

  1. Micromachining Techniques in Developing High-Frequency Piezoelectric Composite Ultrasonic Array Transducers

    PubMed Central

    Liu, Changgeng; Djuth, Frank T.; Zhou, Qifa; Shung, K. Kirk

    2014-01-01

    Several micromachining techniques for the fabrication of high-frequency piezoelectric composite ultrasonic array transducers are described in this paper. A variety of different techniques are used in patterning the active piezoelectric material, attaching backing material to the transducer, and assembling an electronic interconnection board for transmission and reception from the array. To establish the feasibility of the process flow, a hybrid test ultrasound array transducer consisting of a 2-D array having an 8 × 8 element pattern and a 5-element annular array was designed, fabricated, and assessed. The arrays are designed for a center frequency of ~60 MHz. The 2-D array elements are 105 × 105 μm in size with 5-μm kerfs between elements. The annular array surrounds the square 2-D array and provides the option of transmitting from the annular array and receiving with the 2-D array. Each annular array element has an area of 0.71 mm2 with a 16-μm kerf between elements. The active piezoelectric material is (1 − x) Pb(Mg1/3Nb2/3)O3−xPbTiO3 (PMN-PT)/epoxy 1–3 composite with a PMN-PT pillar lateral dimension of 8 μm and an average gap width of ~4 μm, which was produced by deep reactive ion etching (DRIE) dry etching techniques. A novel electric interconnection strategy for high-density, small-size array elements was proposed. After assembly, the array transducer was tested and characterized. The capacitance, pulse–echo responses, and crosstalk were measured for each array element. The desired center frequency of ~60 MHz was achieved and the −6-dB bandwidth of the received signal was ~50%. At the center frequency, the crosstalk between adjacent 2-D array elements was about −33 dB. The techniques described herein can be used to build larger arrays containing smaller elements. PMID:24297027

  2. Operational verification of a 40-MHz annular array transducer

    PubMed Central

    Ketterling, Jeffrey A.; Ramachandran, Sarayu; Aristizäbal, Orlando

    2006-01-01

    An experimental system to take advantage of the imaging capabilities of a 5-ring polyvinylidene fluoride (PVDF) based annular array is presented. The array has a 6 mm total aperture and a 12 mm geometric focus. The experimental system is designed to pulse a single element of the array and then digitize the received data of all array channels simultaneously. All transmit/receive pairs are digitized and then the data are post-processed with a synthetic focusing technique to achieve an enhanced depth of field (DOF). The performance of the array is experimentally tested with a wire phantom consisting of 25-μm diameter wires diagonally spaced at 1 mm by 1 mm intervals. The phantom permitted the efficacy of the synthetic focusing algorithm to be tested and was also used for two-way beam characterization. Experimental results are compared to a spatial impulse response method beam simulation. After synthetic focusing, the two-way echo amplitude was enhanced over the range of 8 to 19 mm and the 6-dB DOF spanned from 9 to 15 mm. For a wire at a fixed axial depth, the relative time delays between transmit/receive ring pairs agreed with theoretical predictions to within ± 2 ns. To further test the system, B-mode images of an excised bovine eye are rendered. PMID:16555771

  3. Phase multiplying electronic scanning array

    NASA Technical Reports Server (NTRS)

    Seaton, A. F.

    1969-01-01

    Scanning array was designed with properties of low RF loss and phase control. The array consists of a series of special waveguides, hybrids made up of two variable reactance branch arms for input signals, an edge slot for the difference port, and a sum arm for the unradiated signal.

  4. TOPICAL REVIEW: Capacitive micromachined ultrasonic transducer arrays for minimally invasive medical ultrasound

    NASA Astrophysics Data System (ADS)

    Chen, Jingkuang

    2010-02-01

    This paper reviews the minimally invasive capacitive micromachined ultrasonic transducer (CMUT) arrays for medical diagnosis and therapy. While piezoelectric transducers dominate today's medical ultrasound market, the capacitive micromachined ultrasonic transducer has recently emerged as a promising alternative which delivers a comparable device performance to its piezoelectric counterparts, is compatible with front-end circuit integration, allows high-density imager integration and is relative easy in miniaturization. Utilizing MEMS technology, the substrate of CMUT arrays can be micromachined into miniature platforms with various geometrical shapes, which include needles, three-dimensional prisms, as well as other flexible-substrate configurations. These arrays are useful for reaching deep inside the tissue or an organ with a minimally invasive approach. Due to the close proximity of the transducers to the target organ/tissue, a higher resolution/accuracy of diagnostic information can be achieved. In addition to pulse-echo and photoacoustic imaging, high-power CMUT devices capable of delivering ultrasounds with a pressure greater than 1.0 MPa have been monolithically integrated with imager CMUTs for image-guided therapy (IGT). Such miniature devices would facilitate diagnostic and therapy interventions not possible with conventional piezoelectric transducers.

  5. Piezoelectric Micromachined Ultrasound Transducer (PMUT) Arrays for Integrated Sensing, Actuation and Imaging

    PubMed Central

    Qiu, Yongqiang; Gigliotti, James V.; Wallace, Margeaux; Griggio, Flavio; Demore, Christine E. M.; Cochran, Sandy; Trolier-McKinstry, Susan

    2015-01-01

    Many applications of ultrasound for sensing, actuation and imaging require miniaturized and low power transducers and transducer arrays integrated with electronic systems. Piezoelectric micromachined ultrasound transducers (PMUTs), diaphragm-like thin film flexural transducers typically formed on silicon substrates, are a potential solution for integrated transducer arrays. This paper presents an overview of the current development status of PMUTs and a discussion of their suitability for miniaturized and integrated devices. The thin film piezoelectric materials required to functionalize these devices are discussed, followed by the microfabrication techniques used to create PMUT elements and the constraints the fabrication imposes on device design. Approaches for electrical interconnection and integration with on-chip electronics are discussed. Electrical and acoustic measurements from fabricated PMUT arrays with up to 320 diaphragm elements are presented. The PMUTs are shown to be broadband devices with an operating frequency which is tunable by tailoring the lateral dimensions of the flexural membrane or the thicknesses of the constituent layers. Finally, the outlook for future development of PMUT technology and the potential applications made feasible by integrated PMUT devices are discussed. PMID:25855038

  6. Piezoelectric micromachined ultrasound transducer (PMUT) arrays for integrated sensing, actuation and imaging.

    PubMed

    Qiu, Yongqiang; Gigliotti, James V; Wallace, Margeaux; Griggio, Flavio; Demore, Christine E M; Cochran, Sandy; Trolier-McKinstry, Susan

    2015-01-01

    Many applications of ultrasound for sensing, actuation and imaging require miniaturized and low power transducers and transducer arrays integrated with electronic systems. Piezoelectric micromachined ultrasound transducers (PMUTs), diaphragm-like thin film flexural transducers typically formed on silicon substrates, are a potential solution for integrated transducer arrays. This paper presents an overview of the current development status of PMUTs and a discussion of their suitability for miniaturized and integrated devices. The thin film piezoelectric materials required to functionalize these devices are discussed, followed by the microfabrication techniques used to create PMUT elements and the constraints the fabrication imposes on device design. Approaches for electrical interconnection and integration with on-chip electronics are discussed. Electrical and acoustic measurements from fabricated PMUT arrays with up to 320 diaphragm elements are presented. The PMUTs are shown to be broadband devices with an operating frequency which is tunable by tailoring the lateral dimensions of the flexural membrane or the thicknesses of the constituent layers. Finally, the outlook for future development of PMUT technology and the potential applications made feasible by integrated PMUT devices are discussed. PMID:25855038

  7. Distributed phased array architecture study

    NASA Technical Reports Server (NTRS)

    Bourgeois, Brian

    1987-01-01

    Variations in amplifiers and phase shifters can cause degraded antenna performance, depending also on the environmental conditions and antenna array architecture. The implementation of distributed phased array hardware was studied with the aid of the DISTAR computer program as a simulation tool. This simulation provides guidance in hardware simulation. Both hard and soft failures of the amplifiers in the T/R modules are modeled. Hard failures are catastrophic: no power is transmitted to the antenna elements. Noncatastrophic or soft failures are modeled as a modified Gaussian distribution. The resulting amplitude characteristics then determine the array excitation coefficients. The phase characteristics take on a uniform distribution. Pattern characteristics such as antenna gain, half power beamwidth, mainbeam phase errors, sidelobe levels, and beam pointing errors were studied as functions of amplifier and phase shifter variations. General specifications for amplifier and phase shifter tolerances in various architecture configurations for C band and S band were determined.

  8. Phased arrays 1985 symposium: Proceedings

    NASA Astrophysics Data System (ADS)

    Steyskal, H. P.

    1985-08-01

    The Phased Arrays '85 Symposium, sponsored by the Rome Air Development Center, the MITRE Corporation, and the University of Massachusetts, was held at the MITRE Corporation 15 to 18 October and reviewed the state-of-the-art of phased array antenna systems and of the technology for next generation systems. This report contains the full papers which were presented with clearance for unlimited distribution.

  9. 7.5 MHz dual-layer transducer array for 3-D rectilinear imaging.

    PubMed

    Chen, Yuling; Nguyen, Man; Yen, Jesse T

    2011-07-01

    The difficulties associated with fabrication and interconnection have limited the development of 2-D ultrasound transducer arrays with a large number ofelements (>5000). In previous work, we described a 5 MHz center frequency PZT-P[VDF-TrFE] dual-layer transducer that used two perpendicular 1-D arrays for 3-D rectilinear imaging. This design substantially reduces the channel count as well as fabrication complexity, which makes 3-D imaging more realizable. Higher frequencies (>5 MHz) are more commonly used in clinical applications or imaging targets near transducers, such as the breast, carotid and musculoskeletal tissue. In this paper, we present a 7.5 MHz dual-layer transducer array for 3-D rectilinear imaging. A modified acoustic stack model was designed and fabricated. PZT elements were sub-diced to eliminate lateral coupling. This sub-dicing process made the PZT into a 2-2 composite material, which could help improve transducer sensitivity and bandwidth. Full synthetic-aperture 3-D data sets were acquired by interfacing the transducer with a Verasonics data-acquisition system (VDAS). Offline 3-D beamforming was then performed to obtain volumes of a multiwire phantom and a cyst phantom. The generalized coherence factor (GCF) was applied to improve the contrast of cyst images. The measured -6 dB fractional bandwidth of the transducer was 71% with a center frequency of 7.5 MHz. The measured lateral beamwidths were 0.521 mm and 0.482 mm in azimuth and elevation, respectively, compared with a simulated beamwidth of 0.43 mm. PMID:21842584

  10. A 7.5 MHz Dual-Layer Transducer Array for 3-D Rectilinear Imaging

    PubMed Central

    Chen, Yuling; Nguyen, Man; Yen, Jesse T.

    2011-01-01

    The difficulties associated with fabrication and interconnection have limited the development of 2-D ultrasound transducer arrays with a large number of elements (>5000). In previous work, we described a 5 MHz center frequency PZT-P[VDF-TrFE] dual-layer transducer, which used 2 perpendicular 1-D arrays for 3-D rectilinear imaging. This design substantially reduces the channel count as well as fabrication complexity, which makes 3-D imaging more realizable. Higher frequencies (>5MHz) are more commonly used in clinical for imaging targets near transducers such as the breast, carotid, and musculoskeletal. In this paper, we present a 7.5 MHz dual-layer transducer array for 3-D rectilinear imaging. A modified acoustic stack model was designed and fabricated. PZT elements were sub-diced to eliminate lateral coupling. This sub-dicing process made the PZT into a 2–2 composite material, which could help improve transducer sensitivity and bandwidth. Full synthetic aperture 3-D data sets were acquired by interfacing the transducer with a Verasonics data acquisition system (VDAS). Offline 3-D beamforming was then performed to obtain volumes of a multi-wire phantom and a cyst phantom. The generalized coherence factor (GCF) was applied to improve the contrast of cyst images. The measured −6 dB fractional bandwidth of the transducer was 71% with a center frequency of 7.5 MHz. The measured lateral beamwidths were 0.521 mm and 0.482 mm in azimuth and elevation respectively, compared with a simulated beamwidth of 0.43 mm. PMID:21842584

  11. MRI-compatible ultrasound heating system with ring-shaped phased arrays for breast tumor thermal therapy.

    PubMed

    Chen, Hung-Nien; Chen, Guan-Ming; Lin, Bo-Sian; Lien, Pi-Hsien; Chen, Yung-Yaw; Chen, Gin-Shin; Lin, Win-Li

    2013-01-01

    Therapeutic ultrasound transducers can carry out precise and efficient power deposition for tumor thermal therapy under the guidance of magnetic resonance imaging. For a better heating, organ-specific ultrasound transducers with precision location control system should be developed for tumors located at various organs. It is feasible to perform a better heating for breast tumor thermal therapy with a ring-shaped ultrasound phased-array transducer. In this study, we developed ring-shaped phased-array ultrasound transducers with 1.0 and 2.5 MHz and a precision location control system to drive the transducers to the desired location to sonicate the designated region. Both thermo-sensitive hydrogel phantom and ex vivo fresh pork were used to evaluate the heating performance of the transducers. The results showed that the ring-shaped phased array ultrasound transducers were very promising for breast tumor heating with the variation of heating patterns and without overheating the ribs. PMID:24110540

  12. An Ultrasonic Imaging System Using a Matrix-Type Transducer Array

    NASA Astrophysics Data System (ADS)

    Noguchi, Michitoshi; Mizutani, Koichi; Nagai, Keinosuke; Yamashita, Yoshinari

    1999-05-01

    We propose a method for imaging an object's surface using a matrix-type transducer array. The matrix-type transducer array has a simple structure with some line-electrode fingers on both sides of a piezoelectric ceramic plate. By a combination of electrical-mechanical scanning, we image of an object's surface using data of distance between the transducer and the object. The ultrasonic probe used in the present system requires without beam forming and no signal processing for focusing. We measure two objects: one has a multilayered structure consisting of three differently sized aluminum plates, the biggest plate having an area of 150 mm × 80 mm and 0.8 1.5 mm thickness; and the other is a radio-wave-absorbent block 100.5 mm × 100.5 mm × 18.5 mm in size with 5 × 5 holes in a grid made of ferrite. The ultrasonic probe operates at a frequency of 3.5 MHz and the sensing distance between the transducer and the measured object is about 80 mm. At this distance, the diameter of the ultrasonic beam launched from the transducer is about 13 mm. We obtained a height resolution of ±0.2 mm and a spatial resolution of about 3.0 mm.

  13. Lamb and SH wave transducer arrays for the inspection of large areas of thick plates

    NASA Astrophysics Data System (ADS)

    Wilcox, P.; Lowe, M.; Cawley, P.

    2000-05-01

    The motivation for this work is to develop a rapid inspection system for large steel plates, such as those which the floors and walls of oil storage tanks are constructed from. One approach to inspecting plates using guided ultrasonic waves, is to design a transduction system which uses monolithic devices such as wedge transducers, inter-digital transducers or meander coil electro-magnetic acoustic transducers (EMATs). Unfortunately, in order to achieve a given level of performance at a particular operating point on the dispersion curves, the physical dimensions of a monolithic transducer must be scaled in proportion to the thickness of plate under inspection. This renders the use of monolithic devices on thicker plates increasingly impractical for several reasons, not least because of the cost and difficulties involved in manufacturing large devices. Also, particular monolithic devices are limited to a small range of applications since they are generally designed to be sensitive to a particular wavelength and to be either unfocused or have a fixed focal length. A more attractive solution is to use an array device containing a number of elements which behave individually as point transducers. By controlling the elements individually, wavelength selection, beam steering and focusing can all be performed by post processing the same set of test data. Encouraging experimental results obtained using this technique will be shown for several array designs which operate on 5-10 mm thick plates.

  14. A Dual-Layer Transducer Array for 3-D Rectilinear Imaging

    PubMed Central

    Yen, Jesse T.; Seo, Chi Hyung; Awad, Samer I.; Jeong, Jong S.

    2010-01-01

    2-D arrays for 3-D rectilinear imaging require very large element counts (16,000–65,000). The difficulties in fabricating and interconnecting 2-D arrays with a large number of elements (>5,000) have limited the development of suitable transducers for 3-D rectilinear imaging. In this paper, we propose an alternative solution to this problem by using a dual-layer transducer array design. This design consists of two perpendicular 1-D arrays for clinical 3-D imaging of targets near the transducer. These targets include the breast, carotid artery, and musculoskeletal system. This transducer design reduces the fabrication complexity and the channel count making 3-D rectilinear imaging more realizable. With this design, an effective N × N 2-D array can be developed using only N transmitters and N receivers. This benefit becomes very significant when N becomes greater than 128, for example. To demonstrate feasibility, we constructed a 4 × 4 cm prototype dual-layer array. The transmit array uses diced PZT-5H elements, and the receive array is a single sheet of undiced P[VDF-TrFE] copolymer. The receive elements are defined by the copper traces on the flexible interconnect circuit. The measured −6 dB fractional bandwidth was 80% with a center frequency of 4.8 MHz. At 5 MHz, the nearest neighbor crosstalk of the PZT array and PVDF array was −30.4 ± 3.1 dB and −28.8 ± 3.7 dB respectively. This dual-layer transducer was interfaced with an Ultrasonix Sonix RP system, and a synthetic aperture 3-D data set was acquired. We then performed off-line 3-D beamforming to obtain volumes of nylon wire targets. The theoretical lateral beamwidth was 0.52 mm compared to measured beamwidths of 0.65 mm and 0.67 mm in azimuth and elevation respectively. 3-D images of an 8 mm diameter anechoic cyst phantom were also acquired. PMID:19213647

  15. Phase-locked laser array

    NASA Technical Reports Server (NTRS)

    Botez, Dan (Inventor)

    1987-01-01

    A phase-locked laser array comprises a body of semiconductor material having means for defining a plurality of substantially parallel lasing zones which are spaced an effective distance apart so that the modes of the adjacent lasing zones are phase-locked to one another. One of the array electrodes comprises a plurality of electrical contacts to the body between the lasing zones. These contacts provide an enhanced current density profile and thus an increase in the gain in the regions between the lasing zones so that zero degree phase-shift operation between adjacent lasing zones is achievable.

  16. Multi-particle trapping and manipulation by a high-frequency array transducer

    SciTech Connect

    Yoon, Changhan; Kang, Bong Jin; Lee, Changyang; Kim, Hyung Ham Shung, K. Kirk

    2014-11-24

    We report the multiple micro-particle trapping and manipulation by a single-beam acoustic tweezer using a high-frequency array transducer. A single acoustic beam generated by a 30 MHz ultrasonic linear array transducer can entrap and transport multiple micro-particles located at the main lobe and the grating lobes. The distance between trapped particles can be adjusted by changing the transmit arrangement of array-based acoustic tweezers and subsequently the location of grating lobes. The experiment results showed that the proposed method can trap and manipulate multiple particles within a range of hundreds of micrometers. Due to its simplicity and low acoustic power, which is critical to protect cells from any thermal and mechanical damages, the technique may be used for transportation of cells in cell biology, biosensors, and tissue engineering.

  17. Preliminary work of real-time ultrasound imaging system for 2-D array transducer.

    PubMed

    Li, Xu; Yang, Jiali; Ding, Mingyue; Yuchi, Ming

    2015-01-01

    Ultrasound (US) has emerged as a non-invasive imaging modality that can provide anatomical structure information in real time. To enable the experimental analysis of new 2-D array ultrasound beamforming methods, a pre-beamformed parallel raw data acquisition system was developed for 3-D data capture of 2D array transducer. The transducer interconnection adopted the row-column addressing (RCA) scheme, where the columns and rows were active in sequential for transmit and receive events, respectively. The DAQ system captured the raw data in parallel and the digitized data were fed through the field programmable gate array (FPGA) to implement the pre-beamforming. Finally, 3-D images were reconstructed through the devised platform in real-time. PMID:26405923

  18. Detection of plate components defects by surface wave based on transducer arrays

    NASA Astrophysics Data System (ADS)

    Liu, Zhao; Meng, Fanwu; Xu, Chunguang; Li, Xipeng; Zhou, Shiyuan; Xiao, Dingguo

    2013-01-01

    Detection of micro damages in flat components on-site has a significant sense for improving the safety of the equipment. Based on the theory of the surface acoustic wave (SAW) propagation laws in flat components, the micro damage detection in the flat component has been researched. Using wavelet analysis technology and inversed spectrum technology, the microdamages' feature parameters can be extracted out accurately. Utilizing the feature parameters got by every transducer in a transducer arrays, the micro-damages' image can be reconstructed, and the micro-damages' location, outer geometric configuration, and damage level can be showed clearly.

  19. Diffraction aperture non-ideal behaviour of air coupled transducers array elements designed for NDT.

    PubMed

    Prego Borges, J L; Montero de Espinosa, F; Salazar, J; Garcia-Alvarez, J; Chávez, J A; Turó, A; Garcia-Hernandez, M J

    2006-12-22

    Air coupled piezoelectric ultrasonic array transducers are a novel tool that could lead to interesting advances in the area of non-contact laminar material testing using Lamb wave's propagation techniques. A key issue on the development of such transducers is their efficient coupling to air media (impedance mismatch between the piezoelectric material and air is 90 dB or more). Adaptation layers are used in order to attain good matching and avoid possible serious signal degradation. However, the introduction of these matching layers modify the transducer surface behaviour and, consequently, radiation characteristics are altered, making the usual idealization criteria (of uniform surface movement) adopted for field simulation purposes inaccurate. In our system, we have a concave linear-array transducer of 64 elements (electrically coupled by pairs) working at 0.8 MHz made of PZ27 rectangular piezoceramics (15 mm x 0.3 mm) with two matching layers made of polyurethane and porous cellulose bonded on them. Experimental measurements of the acoustic aperture of single excited array elements have shown an increment on the geometrical dimensions of its active surface. A sub-millimeter vibrometer laser scan has revealed an extension of the aperture beyond the supposed physical single array element dimensions. Non-uniform symmetric apodized velocity surface vibration amplitude profile with a concave delay contour indicates the presumed existence of travelling wave phenomena over the surface of the outer array matching layer. Also, asymptotic propagation velocities around 2500 m/s and attenuation coefficient between 15 and 20 dB/mm has been determined for the travelling waves showing clear tendencies. Further comparisons between the experimental measurements of single array element field radiation diagram and simulated equivalent aperture counterpart reveal good agreement versus the ideal (uniform displaced) rectangular aperture. For this purpose an Impulse Response Method

  20. Thermal-independent properties of PIN-PMN-PT single-crystal linear-array ultrasonic transducers.

    PubMed

    Chen, Ruimin; Wu, Jinchuan; Ho Lam, Kwok; Yao, Liheng; Zhou, Qifa; Tian, Jian; Han, Pengdi; Shung, K Kirk

    2012-12-01

    In this paper, low-frequency 32-element linear-array ultrasonic transducers were designed and fabricated using both ternary Pb(In(1/2)Nb(1/2))-Pb(Mg(1/3)Nb(2/3))-PbTiO(3) (PIN-PMN-PT) and binary Pb(Mg(1/3)Nb(2/3))-PbTiO(3) (PMNPT) single crystals. Performance of the array transducers was characterized as a function of temperature ranging from room temperature to 160°C. It was found that the array transducers fabricated using the PIN-PMN-PT single crystal were capable of satisfactory performance at 160°C, having a -6-dB bandwidth of 66% and an insertion loss of 37 dB. The results suggest that the potential of PIN-PMN-PT linear-array ultrasonic transducers for high-temperature ultrasonic transducer applications is promising. PMID:23221227

  1. Analysis of variable-thickness, streamlined transducer array windowing concepts for high speed underwater vehicles

    NASA Astrophysics Data System (ADS)

    Koch, Robert M.

    2002-11-01

    Recent research in very high speed underwater vehicles shows they require a much more streamlined vehicle nose than the present rather flat tactical scale vehicle nose. It has been found that the common forward-facing transducer array with a constant thickness array window utilized on current lower speed vehicles is inadequate. Two newer alternate front-end array concepts suitable for lower drag, higher speed vehicles being investigated are (a) a variable thickness, streamlined array window on a flat forward facing array and (b) a streamlined vehicle nose structure consisting of a built-in distributed, conformal array. While these highly streamlined concepts are attractive from the standpoint of reducing vehicle drag at higher speeds, both require reexamination of the effects of high curvature on front-end sonar array performance. In the present paper, both above streamlined array concepts are numerically examined using the sara2d dynamic structural-acoustic Finite Element Analysis (FEA) code. First, the acoustic performance of a hemispherical array window is compared to a common equal aperture flat window in both transmit (outgoing acoustic wave) and receive (incident acoustic wave) modes. Second, a dynamic simulation of acoustic array beam-forming and beam-steering is performed for a conical shaped conformal array to assess the feasibility of the concept.

  2. Airborne ultrasonic phased arrays using ferroelectrets: a new fabrication approach.

    PubMed

    Ealo, Joao L; Camacho, Jorge J; Fritsch, Carlos

    2009-04-01

    In this work, a novel procedure that considerably simplifies the fabrication process of ferroelectret-based multielement array transducers is proposed and evaluated. Also, the potential of ferroelectrets being used as active material for air-coupled ultrasonic transducer design is demonstrated. The new construction method of multi-element transducers introduces 2 distinctive improvements. First, active ferroelectret material is not discretized into elements, and second, the need of structuring upper and/or lower electrodes in advance of the permanent polarization of the film is removed. The aperture discretization and the mechanical connection are achieved in one step using a through-thickness conductive tape. To validate the procedure, 2 linear array prototypes of 32 elements, with a pitch of 3.43 mm and a wide usable frequency range from 30 to 300 kHz, were built and evaluated using a commercial phased-array system. A low crosstalk among elements, below -30 dB, was measured by interferometry. Likewise, a homogeneous response of the array elements, with a maximum deviation of +/-1.8 dB, was obtained. Acoustic beam steering measurements were accomplished at different deflection angles using a calibrated microphone. The ultrasonic beam parameters, namely, lateral resolution, side lobe level, grating lobes, and focus depth, were congruent with theory. Acoustic images of a single reflector were obtained using one of the array elements as the receiver. Resulting images are also in accordance with numerical simulation, demonstrating the feasibility of using these arrays in pulse-echo mode. The proposed procedure simplifies the manufacturing of multidimensional arrays with arbitrary shape elements and not uniformly distributed. Furthermore, this concept can be extended to nonflat arrays as long as the transducer substrate conforms to a developable surface. PMID:19406714

  3. 2D array transducers for real-time 3D ultrasound guidance of interventional devices

    NASA Astrophysics Data System (ADS)

    Light, Edward D.; Smith, Stephen W.

    2009-02-01

    We describe catheter ring arrays for real-time 3D ultrasound guidance of devices such as vascular grafts, heart valves and vena cava filters. We have constructed several prototypes operating at 5 MHz and consisting of 54 elements using the W.L. Gore & Associates, Inc. micro-miniature ribbon cables. We have recently constructed a new transducer using a braided wiring technology from Precision Interconnect. This transducer consists of 54 elements at 4.8 MHz with pitch of 0.20 mm and typical -6 dB bandwidth of 22%. In all cases, the transducer and wiring assembly were integrated with an 11 French catheter of a Cook Medical deployment device for vena cava filters. Preliminary in vivo and in vitro testing is ongoing including simultaneous 3D ultrasound and x-ray fluoroscopy.

  4. A nano-power energy harvesting IC for arrays of piezoelectric transducers

    NASA Astrophysics Data System (ADS)

    Dini, M.; Filippi, M.; Romani, A.; Bottarel, V.; Ricotti, G.; Tartagni, M.

    2013-05-01

    This paper describes a multi-source energy harvester IC for arrays of independent transducers, designed in a 0.32μm STMicroelectronics BCD technology, that can manage up to 5 AC-DC channels (e.g. piezoelectric transducers). The IC implements a boost converter based on synchronous electrical charge extraction. A single external inductor is time-shared among all transducers and access conflicts are handled by an arbiter circuit implemented as an asynchronous FSM. The designed converter is fully autonomous and suitable for battery-less operation. The circuit area is 4.6 mm2 and has a power consumption of 175 nW/source at 2.5 V while efficiency ranges between 70% and over than 85%.

  5. A 5 MHz Cylindrical Dual-Layer Transducer Array for 3-D Transrectal Ultrasound Imaging

    PubMed Central

    Chen, Yuling; Nguyen, Man; Yen, Jesse T.

    2012-01-01

    2-D transrectal ultrasound (TRUS) is being used in guiding prostate biopsies and treatments. In many cases, the TRUS probes are moved manually or mechanically to acquire volumetric information, making the imaging slow, user-dependent and unreliable. A real-time 3-D TRUS system could improve reliability and volume rates of imaging during these procedures. In this paper, we present a 5 MHz cylindrical dual-layer transducer array capable of real-time 3-D transrectal ultrasound without any mechanically moving parts. Compared to fully-sampled 2-D arrays, this design substantially reduces the channel count and fabrication complexity. This dual-layer transducer uses PZT elements for transmit and P[VDF-TrFE] copolymer elements for receive, respectively. The mechanical flexibility of both diced PZT and copolymer makes it practical for transrectal applications. Full synthetic aperture 3-D data sets were acquired by interfacing the transducer with a Verasonics Data Acquisition System (VDAS). Offline 3-D beamforming was then performed to obtain volumes of two wire phantoms and a cyst phantom. Generalized coherence factor (GCF) was applied to improve the contrast of images. The measured −6 dB fractional bandwidth of the transducer was 62% with a center frequency of 5.66 MHz. The measured lateral beamwidths were 1.28 mm and 0.91 mm in transverse and longitudinal directions respectively, compared with a simulated beamwidth of 0.92 mm and 0.74 mm. PMID:22972914

  6. A preliminary evaluation work on a 3D ultrasound imaging system for 2D array transducer

    NASA Astrophysics Data System (ADS)

    Zhong, Xiaoli; Li, Xu; Yang, Jiali; Li, Chunyu; Song, Junjie; Ding, Mingyue; Yuchi, Ming

    2016-04-01

    This paper presents a preliminary evaluation work on a pre-designed 3-D ultrasound imaging system. The system mainly consists of four parts, a 7.5MHz, 24×24 2-D array transducer, the transmit/receive circuit, power supply, data acquisition and real-time imaging module. The row-column addressing scheme is adopted for the transducer fabrication, which greatly reduces the number of active channels . The element area of the transducer is 4.6mm by 4.6mm. Four kinds of tests were carried out to evaluate the imaging performance, including the penetration depth range, axial and lateral resolution, positioning accuracy and 3-D imaging frame rate. Several strong reflection metal objects , fixed in a water tank, were selected for the purpose of imaging due to a low signal-to-noise ratio of the transducer. The distance between the transducer and the tested objects , the thickness of aluminum, and the seam width of the aluminum sheet were measured by a calibrated micrometer to evaluate the penetration depth, the axial and lateral resolution, respectively. The experiment al results showed that the imaging penetration depth range was from 1.0cm to 6.2cm, the axial and lateral resolution were 0.32mm and 1.37mm respectively, the imaging speed was up to 27 frames per second and the positioning accuracy was 9.2%.

  7. High-resolution sea-bed imaging: an acoustic multiple transducer array

    NASA Astrophysics Data System (ADS)

    Jetté, Christopher D.; Hanes, Daniel M.

    1997-07-01

    A high-resolution sea-bed profiling system is described. The multiple transducer array (MTA) consists of a 37 element linear array of ultra-sonic (5 MHz) transducers. The first prototype MTA described herein measures two-dimensional bedform profiles over a length of 45 cm with approximately 1 mm vertical resolution and 2 cm horizontal resolution. Complete profiles can be recorded every five seconds. Laboratory and field tests of the MTA show the system's capability to accurately measure bedforms of known geometry and the ability to work under conditions with relatively high suspended sediment concentrations. Previous high-resolution profiling systems have either had moving parts, or have been unable to obtain the resolution of the system described here.

  8. Further Development of a Conformable Phased Array Device for Inspection Over Irregular Surfaces

    NASA Astrophysics Data System (ADS)

    Long, R.; Cawley, P.

    2008-02-01

    Further development of a conformable phased array device that allows reliable ultrasonic inspection of components with irregular surfaces has been undertaken. The device uses a standard linear phased array transducer, which is coupled to the surface under test by a water path, encapsulated by a low loss, castable polyurethane rubber membrane. It is shown that the conformable membrane coupled phased array device provides a solution for ultrasonic inspection around the weld region of welded pipes.

  9. Phased Array Feeds

    NASA Astrophysics Data System (ADS)

    Fisher, J. Richard; Bradley, Richard F.; Brisken, Walter F.; Cotton, William D.; Emerson, Darrel T.; Kerr, Anthony R.; Lacasse, Richard J.; Morgan, Matthew A.; Napier, Peter J.; Norrod, Roger D.; Payne, John M.; Pospieszalski, Marian W.; Symmes, Arthur; Thompson, A. Richard; Webber, John C.

    This white paper offers cautionary observations about the planning and development of new, large radio astronomy instruments. Complexity is a strong cost driver so every effort should be made to assign differing science requirements to different instruments and probably different sites. The appeal of shared resources is generally not realized in practice and can often be counterproductive. Instrument optimization is much more difficult with longer lists of requirements, and the development process is longer and less efficient. More complex instruments are necessarily further behind the technology state of the art because of longer development times. Including technology R&D in the construction phase of projects is a growing trend that leads to higher risks, cost overruns, schedule delays, and project de-scoping. There are no technology breakthroughs just over the horizon that will suddenly bring down the cost of collecting area. Advances come largely through careful attention to detail in the adoption of new technology provided by industry and the commercial market. Radio astronomy instrumentation has a very bright future, but a vigorous long-term R&D program not tied directly to specific projects needs to be restored, fostered, and preserved.

  10. Airborne electronically steerable phased array

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The results are presented of the second stage of a program for the design and development of a phased array capable of simultaneous and separate transmission and reception of radio frequency signals at S-band frequencies. The design goals of this stage were the development of three major areas of interest required for the final prototype model. These areas are the construction and testing of the low-weight, full-scale 128-element array of antenna elements, the development of the RF manifold feed system, and the construction and testing of a working module containing diplexer and transmit and receive circuits.

  11. A Beamforming Study for Implementation of Vibro-acoustography with a 1.75D Array Transducer

    PubMed Central

    Urban, Matthew W.; Chalek, Carl; Haider, Bruno; Thomenius, Kai E.; Fatemi, Mostafa; Alizad, Azra

    2013-01-01

    Vibro-acoustography (VA) is an ultrasound-based imaging modality that uses radiation force produced by two cofocused ultrasound beams separated by a small frequency difference, Δf, to vibrate tissue at Δf. An acoustic field is created by the object vibration and measured with a nearby hydrophone. This method has recently been implemented on a clinical ultrasound system using one-dimensional (1D) linear array transducers. In this article, we discuss VA beamforming and image formation using a 1.75D array transducer. A 1.75D array transducer has several rows of elements in the elevation direction which can be controlled independently for focusing. The advantage of the 1.75D array over a 1D linear array transducer is that multiple rows of elements can be used for improving elevation focus for imaging formation. Six configurations for subaperture design for the two ultrasound beams necessary for VA imaging were analyzed. The point-spread functions for these different configurations were evaluated using a numerical simulation model. Four of these configurations were then chosen for experimental evaluation with a needle hydrophone as well as for scanning two phantoms. Images were formed by scanning a urethane breast phantom and an ex vivo human prostate. VA imaging using a 1.75D array transducer offers several advantages over scanning with a linear array transducer including improved image resolution and contrast due to better elevation focusing of the imaging point-spread function. PMID:23475919

  12. A beamforming study for implementation of vibro-acoustography with a 1.75-D array transducer.

    PubMed

    Urban, Matthew W; Chalek, Carl; Haider, Bruno; Thomenius, Kai E; Fatemi, Mostafa; Alizad, Azra

    2013-03-01

    Vibro-acoustography (VA) is an ultrasound-based imaging modality that uses radiation force produced by two cofocused ultrasound beams separated by a small frequency difference, Δf, to vibrate tissue at Δf. An acoustic field is created by the object vibration and measured with a nearby hydrophone. This method has recently been implemented on a clinical ultrasound system using 1-D linear-array transducers. In this article, we discuss VA beamforming and image formation using a 1.75-D array transducer. A 1.75-D array transducer has several rows of elements in the elevation direction which can be controlled independently for focusing. The advantage of the 1.75-D array over a 1-D linear-array transducer is that multiple rows of elements can be used for improving elevation focus for imaging formation. Six configurations for subaperture design for the two ultrasound beams necessary for VA imaging were analyzed. The point-spread functions for these different configurations were evaluated using a numerical simulation model. Four of these configurations were then chosen for experimental evaluation with a needle hydrophone as well as for scanning two phantoms. Images were formed by scanning a urethane breast phantom and an ex vivo human prostate. VA imaging using a 1.75-D array transducer offers several advantages over scanning with a linear-array transducer, including improved image resolution and contrast resulting from better elevation focusing of the imaging point-spread function. PMID:23475919

  13. Cabling design for phased arrays

    NASA Technical Reports Server (NTRS)

    Kruger, I. D.; Turkiewicz, L.

    1972-01-01

    The ribbon-cabling system used for the AEGIS phased array which provides minimum cable bulk, complete EMI shielding, rugged mechanical design, repeatable electrical characteristics, and ease of assembly and maintenance is described. The ribbon cables are 0.040-inch thick, and in widths up to 2 1/2 inches. Their terminations are molded connectors that can be grouped in a three-tier arrangement, with cable branching accomplished by a matrix-welding technique.

  14. Screen-printed ultrasonic 2-D matrix array transducers for microparticle manipulation.

    PubMed

    Qiu, Yongqiang; Wang, Han; Gebhardt, Sylvia; Bolhovitins, Aleksandrs; Démoré, Christine E M; Schönecker, Andreas; Cochran, Sandy

    2015-09-01

    This paper reports the development of a two-dimensional thick film lead zirconate titanate (PZT) ultrasonic transducer array, operating at frequency approximately 7.5MHz, to demonstrate the potential of this fabrication technique for microparticle manipulation. All layers of the array are screen-printed then sintered on an alumina substrate without any subsequent patterning processes. The thickness of the thick film PZT is 139±2μm, the element pitch of the array is 2.3mm, and the dimension of each individual PZT element is 2×2mm(2) with top electrode 1.7×1.7mm(2). The measured relative dielectric constant of the PZT is 2250±100 and the dielectric loss is 0.09±0.005 at 10kHz. Finite element analysis was used to predict the behaviour of the array and to optimise its configuration. Electrical impedance spectroscopy and laser vibrometry were used to characterise the array experimentally. The measured surface motion of a single element is on the order of tens of nanometres with a 10Vpeak continuous sinusoidal excitation. Particle manipulation experiments have been demonstrated with the array by manipulating Ø10μm polystyrene microspheres in degassed water. The simplified array fabrication process and the bulk production capability of screen-printing suggest potential for the commercialisation of multilayer planar resonant devices for ultrasonic particle manipulation. PMID:26026870

  15. A top-crossover-to-bottom addressed segmented annular array using piezoelectric micromachined ultrasonic transducers

    NASA Astrophysics Data System (ADS)

    Jung, Joontaek; Lee, Wonjun; Kang, Woojin; Hong, Hyeryung; Yuen Song, Hi; Oh, Inn-yeal; Park, Chul Soon; Choi, Hongsoo

    2015-11-01

    We design and fabricate segmented annular arrays (SAAs) using piezoelectric micromachined ultrasonic transducers (pMUTs) to demonstrate the feasibility of acoustic focusing of ultrasound. The fabricated SAAs have 25 concentric top-electrode signal lines and eight bottom-electrodes for grounding to enable electronic steering of selectively grouped ultrasonic transducers from 2393 pMUT elements. Each element in the array is connected by top-crossover-to-bottom metal bridges, which reduce the parasitic capacitance. Circular-shaped pMUT elements, 120 μm in diameter, are fabricated using 1 μm-thick sol-gel lead zirconate titanate on a silicon wafer. To utilize the high-density pMUT array, a deep reactive ion etching process is used for anisotropic silicon etching to realize the transducer membranes. The resonant frequency and effective coupling coefficient of the elements, measured with an impedance analyzer, yields 1.517 MHz and 1.29%, respectively, in air. The SAAs using pMUTs are packaged on a printed circuit board and coated with parylene C for acoustic intensity measurements in water. The ultrasound generated by each segmented array is focused on a selected point in space. When a 5 Vpp, 1.5 MHz square wave is applied, the maximum spatial peak temporal average intensity ({{I}\\text{spta}} ) is found to be 79 mW cm-2 5 mm from the SAAs’ surface without beamforming. The beam widths (-3 dB) of ultrasonic radiation patterns in the elevation and azimuth directions are recorded as 3 and 3.4 mm, respectively. The results successfully show the feasibility of focusing ultrasound on a small area with SAAs using pMUTs.

  16. VHF-induced thermoacoustic imaging of fresh human prostates using a clinical ultrasound transducer array

    NASA Astrophysics Data System (ADS)

    Patch, S. K.; See, W. A.

    2016-03-01

    The purpose of this work was to demonstrate that a clinical ultrasound transducer array can practically detect thermoacoustic pulses induced by irradiation by very high frequency (VHF) electromagnetic energy. This is an important step because thermoacoustic signal strength is directly proportional to the specific absorption rate (SAR), which is lower in the VHF regime than in microwave or optical regimes. A 96-channel transducer array (P4-1) providing 3 cm coverage was incorporated into a benchtop thermoacoustic imaging system for imaging fresh surgical specimens. Thermoacoustic signal was generated by 700 ns irradiation pulses with 11 kV/m electric field strength and 108 MHz carrier frequency. To improve SNR 1024 pulses were averaged at a 250 Hz repetition rate. Two sets of sinograms were acquired, separated by a 2 cm translation along the tomographic axis and reconstructed over a 6 x 6 x 5 cm3 volume. Contrast and in-plane resolution were measured by imaging a homogeneous cylindrical phantom and an 80- micron wire designed to highlight E-field polarization effects. FWHM of the in-plane point spread function varied from 250 microns to 1.1 mm, depending upon transducer used and phantom orientation relative to the electric field. Several fresh human prostates were imaged immediately after surgery. Rudimentary comparison to histology was performed and volumetric reconstruction of the multi-channel P4-1 data visualizes anatomic features that are rarely seen in ultrasound, CT, or MRI. The single element transducer provided superior image contrast, but with inferior resolution.

  17. New fabrication techniques for ring-array transducers for real-time 3D intravascular ultrasound.

    PubMed

    Light, Edward D; Lieu, Victor; Smith, Stephen W

    2009-10-01

    We have previously described miniature 2D array transducers integrated into a Cook Medical, Inc. vena cava filter deployment device. While functional, the fabrication technique was very labor intensive and did not lend itself well to efficient fabrication of large numbers of devices. We developed two new fabrication methods that we believe can be used to efficiently manufacture these types of devices in greater than prototype numbers. One transducer consisted of 55 elements operating near 5 MHz. The interelement spacing is 0.20 mm. It was constructed on a flat piece of copper-clad polyimide and then wrapped around an 11 French catheter of a Cook Medical, Inc. inferior vena cava (IVC) filter deployment device. We used a braided wiring technology from Tyco Electronics Corp. to connect the elements to our real-time 3D ultrasound scanner. Typical measured transducer element bandwidth was 20% centered at 4.7 MHz and the 50 Omega round trip insertion loss was --82 dB. The mean of the nearest neighbor cross talk was -37.0 dB. The second method consisted of a 46-cm long single layer flex circuit from MicroConnex that terminates in an interconnect that plugs directly into our system cable. This transducer had 70 elements at 0.157 mm interelement spacing operating at 4.8 MHz. Typical measured transducer element bandwidth was 29% and the 50 Omega round trip insertion loss was -83 dB. The mean of the nearest neighbor cross talk was -33.0 dB. PMID:20458877

  18. Control of phased-array antennas

    NASA Astrophysics Data System (ADS)

    Samoilenko, V. I.; Shishov, Iu. A.

    Principles and algorithms for the control of phased arrays are described. Particular consideration is given to algorithms for the control of phase distribution, adaptive arrays, beam-steerable arrays, the design of phase shifters, the compensation of beam-pointing errors, and the calibration of high-gain antenna pointing.

  19. Infrared phased-array sensor

    NASA Astrophysics Data System (ADS)

    Slovick, Brian A.; Bean, Jeffrey A.; Florence, Lou A.; Boreman, Glenn D.

    2011-06-01

    Metal-oxide-metal (MOM) tunnel diode detectors when integrated with phased-array antennas provide determination of the angle of arrival and degree of coherence of received infrared radiation. Angle-of-arrival measurements are made with a pair of dipole antennas coupled to a MOM diode through a coplanar strip transmission line. The direction of maximum angular response is altered by varying the position of the MOM diode along the transmission line connecting the antenna elements. Phased-array antennas can also be used to measure the degree of coherence of a partially coherent infrared field. With a two-element array, the degree of coherence is a measure of the correlation of electric fields received by the antennas as a function of the element separation. Antenna-coupled MOM diode devices are fabricated using electron beam lithography and thin-film deposition through a resist shadow mask. Measurements at 10.6 μm are substantiated by electromagnetic simulations and compared to analytic results.

  20. Dynamic response of an insonified sonar window interacting with a Tonpilz transducer array.

    PubMed

    Hull, Andrew J

    2007-08-01

    This paper derives and evaluates an analytical model of an insonified sonar window in contact with an array of Tonpilz transducers operating in receive mode. The window is fully elastic so that all wave components are present in the analysis. The output of the model is a transfer function of a transducer element output voltage divided by input pressure versus arrival angle and frequency. This model is intended for analysis of sonar systems that are to be built or modified for broadband processing. The model is validated at low frequency with a comparison to a previously derived thin plate model. Once this is done, an example problem is studied so that the effects of higher order wave interaction with acoustic reception can be understood. It was found that these higher order waves cause multiple nulls in the region where the array detects acoustic energy and that their locations in the arrival angle-frequency plane can be determined. The effects of these nulls in the beam patterns of the array are demonstrated. PMID:17672630

  1. Detection of foreign body using fast thermoacoustic tomography with a multielement linear transducer array

    SciTech Connect

    Nie Liming; Xing Da; Yang Diwu; Zeng Lvming; Zhou Quan

    2007-04-23

    Current imaging modalities face challenges in clinical applications due to limitations in resolution or contrast. Microwave-induced thermoacoustic imaging may provide a complementary modality for medical imaging, particularly for detecting foreign objects due to their different absorption of electromagnetic radiation at specific frequencies. A thermoacoustic tomography system with a multielement linear transducer array was developed and used to detect foreign objects in tissue. Radiography and thermoacoustic images of objects with different electromagnetic properties, including glass, sand, and iron, were compared. The authors' results demonstrate that thermoacoustic imaging has the potential to become a fast method for surgical localization of occult foreign objects.

  2. In-flight measurement of ice growth on an airfoil using an array of ultrasonic transducers

    NASA Technical Reports Server (NTRS)

    Hansman, R. John, Jr.; Kirby, Mark S.; Mcknight, Robert C.; Humes, Robert L.

    1988-01-01

    Results of preliminary tests to measure ice growth on an airfoil during flight icing conditions are presented. Ultrasonic pulse echo measurements of ice thickness are obtained from an array of eight ultrasonic transducers mounted flush with the leading edge of the airfoil. These thickness measurements are used to document the evolution of the ice shape during the encounter in the form of successive ice profiles. Results from 3 research flights are presented and discussed. The accuracy of the ultrasonic measurements is found to be within 0.5 mm of mechanical and stereo photograph measurements of the ice accretion.

  3. Imaging phased telescope array study

    NASA Technical Reports Server (NTRS)

    Harvey, James E.

    1989-01-01

    The problems encountered in obtaining a wide field-of-view with large, space-based direct imaging phased telescope arrays were considered. After defining some of the critical systems issues, previous relevant work in the literature was reviewed and summarized. An extensive list was made of potential error sources and the error sources were categorized in the form of an error budget tree including optical design errors, optical fabrication errors, assembly and alignment errors, and environmental errors. After choosing a top level image quality requirment as a goal, a preliminary tops-down error budget allocation was performed; then, based upon engineering experience, detailed analysis, or data from the literature, a bottoms-up error budget reallocation was performed in an attempt to achieve an equitable distribution of difficulty in satisfying the various allocations. This exercise provided a realistic allocation for residual off-axis optical design errors in the presence of state-of-the-art optical fabrication and alignment errors. Three different computational techniques were developed for computing the image degradation of phased telescope arrays due to aberrations of the individual telescopes. Parametric studies and sensitivity analyses were then performed for a variety of subaperture configurations and telescope design parameters in an attempt to determine how the off-axis performance of a phased telescope array varies as the telescopes are scaled up in size. The Air Force Weapons Laboratory (AFWL) multipurpose telescope testbed (MMTT) configuration was analyzed in detail with regard to image degradation due to field curvature and distortion of the individual telescopes as they are scaled up in size.

  4. A Method for Accurate in silico modeling of Ultrasound Transducer Arrays

    PubMed Central

    Guenther, Drake A.; Walker, William F.

    2009-01-01

    This paper presents a new approach to improve the in silico modeling of ultrasound transducer arrays. While current simulation tools accurately predict the theoretical element spatio-temporal pressure response, transducers do not always behave as theorized. In practice, using the probe's physical dimensions and published specifications in silico, often results in unsatisfactory agreement between simulation and experiment. We describe a general optimization procedure used to maximize the correlation between the observed and simulated spatio-temporal response of a pulsed single element in a commercial ultrasound probe. A linear systems approach is employed to model element angular sensitivity, lens effects, and diffraction phenomena. A numerical deconvolution method is described to characterize the intrinsic electro-mechanical impulse response of the element. Once the response of the element and optimal element characteristics are known, prediction of the pressure response for arbitrary apertures and excitation signals is performed through direct convolution using available tools. We achieve a correlation of 0.846 between the experimental emitted waveform and simulated waveform when using the probe's physical specifications in silico. A far superior correlation of 0.988 is achieved when using the optimized in silico model. Electronic noise appears to be the main effect preventing the realization of higher correlation coefficients. More accurate in silico modeling will improve the evaluation and design of ultrasound transducers as well as aid in the development of sophisticated beamforming strategies. PMID:19041997

  5. Phased Array Probe Optimization for the Inspection of Titanium Billets

    NASA Astrophysics Data System (ADS)

    Rasselkorde, E.; Cooper, I.; Wallace, P.; Lupien, V.

    2010-02-01

    The manufacturing process of titanium billets can produce multiple sub-surface defects that are particularly difficult to detect during the early stages of production. Failure to detect these defects can lead to subsequent in-service failure. A new and novel automated quality control system is being developed for the inspection of titanium billets destined for use in aerospace applications. The sensors will be deployed by an automated system to minimise the use of manual inspections, which should improve the quality and reliability of these critical inspections early on in the manufacturing process. This paper presents the first part of the work, which is the design and the simulation of the phased array ultrasonic inspection of the billets. A series of phased array transducers were designed to optimise the ultrasonic inspection of a ten inch diameter billet made from Titanium 6Al-4V. A comparison was performed between different probes including a 2D annular sectorial array.

  6. Waveguide piezoelectric micromachined ultrasonic transducer array for short-range pulse-echo imaging

    NASA Astrophysics Data System (ADS)

    Lu, Y.; Tang, H.; Wang, Q.; Fung, S.; Tsai, J. M.; Daneman, M.; Boser, B. E.; Horsley, D. A.

    2015-05-01

    This paper presents an 8 × 24 element, 100 μm-pitch, 20 MHz ultrasound imager based on a piezoelectric micromachined ultrasonic transducer (PMUT) array having integrated acoustic waveguides. The 70 μm diameter, 220 μm long waveguides function both to direct acoustic waves and to confine acoustic energy, and also to provide mechanical protection for the PMUT array used for surface-imaging applications such as an ultrasonic fingerprint sensor. The imager consists of a PMUT array bonded with a CMOS ASIC using wafer-level conductive eutectic bonding. This construction allows each PMUT in the array to have a dedicated front-end receive amplifier, which together with on-chip analog multiplexing enables individual pixel read-out with high signal-to-noise ratio through minimized parasitic capacitance between the PMUT and the front-end amplifier. Finite element method simulations demonstrate that the waveguides preserve the pressure amplitude of acoustic pulses over distances of 600 μm. Moreover, the waveguide design demonstrated here enables pixel-by-pixel readout of the ultrasound image due to improved directivity of the PMUT by directing acoustic waves and creating a pressure field with greater spatial uniformity at the end of the waveguide. Pulse-echo imaging experiments conducted using a one-dimensional steel grating demonstrate the array's ability to form a two-dimensional image of a target.

  7. Compact interferometer transducer based on surface plasmon phase resonance.

    PubMed

    Hadjar, Yassine; Renault, Mikael; Blaize, Sylvain; Bruyant, Aurélien; Vincent, Rémi; Hmima, Abdelhamid

    2015-05-01

    We propose a new monolithic interferometric configuration and implement a novel method for spectroscopic phase shift detection of surface plasmon resonance (SPR) sensors. The interference pattern is obtained using a nonpolarizing beam splitter cube with two attached right angle prisms in such a way that each interference field undergoes two total internal reflections (TIR) at prisms/air interface and one attenuated total reflection (ATR) through surface plasmon interaction. The evanescent part of the interferogram around the Zero optical path difference (ZOPD) is sampled and detected in the far field, thanks to a bidimensional array of scattering optical near-field probes deposited on the corresponding prism surface. A Fourier transform of the sampled interferogram is performed to measure the input light wavelength, while a direct comparison of the interferogram in TM and TE polarization modes allows us to determine the differential phase shift induced by the SPR layer. The phase shift measurement is made possible thanks to a remarkable time stability of the interferogram in the glass bulk. By tuning the input laser wavelength around the resonance, we show a good agreement between experimental and theoretical calculations for both amplitude and phase spectral responses. PMID:26366899

  8. Optical metrology of AlN piezomachined ultrasonic transducer arrays and piezopumps

    NASA Astrophysics Data System (ADS)

    Mązik, Mateusz; Taha, Inas; Flores, Raquel; Janeiro, Ricardo; Viegas, Jaime

    2015-02-01

    Piezomachined ultrasonic transducer (PMUT) arrays are commonly found in applications in the field of ultrasonography and gesture recognition systems. Their application for bio and chemical sample preparation is another possibility, based on their beam steering and acoustic field manipulation capabilities. Post-fabrication non-destructive measurement of key device temporal and spatial parameters is required in order to adjust either simulation models or tune fabrication steps. In this work we report an optical testing setup for measuring the acoustic spectrum of PMUT devices and arrays, characterize maximum deflection of PMUTs and piezopumps and investigate the load effect of electrical contacts on the spatial and temporal oscillation behavior of these piezoelectric structures. Spatial parameters are evaluated with digital holography and temporal parameters with single point Doppler shift and frequency-shifted. We employ this testing setup to measure our own designed PMUT structures which were fabricated at IME-Singapore, evaluating the relative merits of the PMUT design parameters.

  9. Phased array radars - Present and future

    NASA Astrophysics Data System (ADS)

    Pell, Christopher

    1989-12-01

    The characteristics of tactical defense phased-array radars mainly employing two-dimensional electronic beam alignment are reviewed. Technology issues connected with the phased-array architecture and array control are examined. Technical summaries are then given for a representative selection of projected future operational systems, i.e, EMPAR, Multifire, and MESAR.

  10. Proceedings: EPRI Second Phased Array Inspection Seminar

    SciTech Connect

    2001-11-01

    The Second EPRI Phased Array Inspection Seminar focused on industrial applications of phased array technology that have been achieved to date or are planned for the near future. Presentations were made by developers of inspection techniques, inspection services vendors, and utility personnel who have performed inspections using arrays.

  11. Generation of the Ultrasonic Guided Waves in a Seamless Stainless Steel Pipe Using an Array Transducer

    NASA Astrophysics Data System (ADS)

    Kim, Young H.; Song, Sung-Jin; Park, Joon-Soo; Jeon, Jin Hong; Kim, Jae-Hee; Eom, Heung-Sup; Im, Kwang Hee

    2005-04-01

    Ultrasonic guided waves have been widely employed for the long range inspection of structures such as plates, rods and pipes. In ultrasonic guided waves, however, there are numerous modes with different wave velocities, so that the generation and detection of the appropriate wave mode of the guided wave is one of key techniques in the application of guided waves. In the present work, mode tuning using an array transducer was investigated with the hardware implements to generate ultrasonic guided waves in a seamless stainless steel pipe. For this purpose, 8-channel ultrasonic pulser/receiver and their controller which enables sequential activation of each channels with given time delay were developed. A series of experiments was carried out in order to demonstrate the feasibility of dynamic tuning of modes by hardware: tuning the mode of the generated guided wave, group velocity measurement, tuned receiving and mode identification. As a result, the selective tuning of wave mode can be achieved by changing the time interval between adjacent elements of an array transducer.

  12. Capacitive Micromachined Ultrasonic Transducer Arrays for Integrated Diagnostic/Therapeutic Catheters

    NASA Astrophysics Data System (ADS)

    Wong, Serena H.; Wygant, Ira O.; Yeh, David T.; Zhuang, Xuefeng; Bayram, Baris; Kupnik, Mario; Oralkan, Omer; Ergun, A. Sanli; Yaralioglu, Goksen G.; Khuri-Yakub, Butrus T.

    2006-05-01

    In recent years, medical procedures have become increasingly non-invasive. These include endoscopic procedures and intracardiac interventions (e.g., pulmonary vein isolation for treatment of atrial fibrillation and plaque ablation for treatment of arteriosclerosis). However, current tools suffer from poor visualization and difficult coordination of multiple therapeutic and imaging devices. Dual-mode (imaging and therapeutic) ultrasound arrays provide a solution to these challenges. A dual-mode transducer can provide focused, noncontact ultrasound suitable for therapy and can be used to provide high quality real-time images for navigation and monitoring of the procedure. In the last decade, capacitive micromachined ultrasonic transducers (CMUTs), have become an attractive option for ultrasonic imaging systems due to their fabrication flexibility, improved bandwidth, and integration with electronics. The CMUT's potential in therapeutic applications has also been demonstrated by surface output pressures as high as 1MPa peak to peak and continuous wave (CW) operation. This paper reviews existing interventional CMUT arrays, demonstrates the feasibility of CMUTs for high intensity focused ultrasound (HIFU), and presents a design for the next-generation CMUTs for integrated imaging and HIFU endoscopic catheters.

  13. Generation of the Ultrasonic Guided Waves in a Seamless Stainless Steel Pipe Using an Array Transducer

    SciTech Connect

    Kim, Young H.; Song, Sung-Jin; Park, Joon-Soo; Jeon, Jin Hong; Kim, Jae-Hee; Eom, Heung-Sup; Im, Kwang Hee

    2005-04-09

    Ultrasonic guided waves have been widely employed for the long range inspection of structures such as plates, rods and pipes. In ultrasonic guided waves, however, there are numerous modes with different wave velocities, so that the generation and detection of the appropriate wave mode of the guided wave is one of key techniques in the application of guided waves. In the present work, mode tuning using an array transducer was investigated with the hardware implements to generate ultrasonic guided waves in a seamless stainless steel pipe. For this purpose, 8-channel ultrasonic pulser/receiver and their controller which enables sequential activation of each channels with given time delay were developed. A series of experiments was carried out in order to demonstrate the feasibility of dynamic tuning of modes by hardware: tuning the mode of the generated guided wave, group velocity measurement, tuned receiving and mode identification. As a result, the selective tuning of wave mode can be achieved by changing the time interval between adjacent elements of an array transducer.

  14. Analysis of phased-array diode lasers

    SciTech Connect

    Hardy, A.; Streifer, W.

    1985-07-01

    An improved, more accurate analysis of phased-array diode lasers is presented, which yields results that differ both qualitatively and quantitatively from those previously employed. A numerical example indicating decreased splitting in array mode gains is included.

  15. Finite-Element Method Analysis of Low-Frequency Wideband Array Composed of Disk Bender Transducers with Differential Connections

    NASA Astrophysics Data System (ADS)

    Yamamoto, Mitsuru; Inoue, Takeshi; Shiba, Hiroshi; Kitamura, Yuta

    2009-07-01

    In recent ocean investigations using underwater sonar transducers, low-frequency and wideband long-range sonar systems have been demanded for strong acoustic radiation and improved detective resolution capability in shallow-sea regions. We developed a disk bender transducer with a dual radiation surface as a miniaturized, light weight, low-frequency, and high-power transducer. However, there were problems in that the fractional bandwidth was small because the radiation surface was far smaller than the radiated wavelength, and the acoustic load per unit radiation area was small. Therefore, we suggest a technique to enable a wideband sonar array using differential connections of multiple disk bender transducers with different resonance frequencies to solve these problems. In this paper, we report results that endorse the above-mentioned technique obtained by finite-element method (FEM) analysis. The results confirm that this technique produces a wideband transducer array with low-frequency and high-power characteristics. We found that a wideband characteristic of more than 100% could be achieved with as a 6 dB fractional bandwidth by differential connection of disk bender transducers with three different resonance frequencies. In addition, we found that a superior horizontally oriented directivity was provided by locating the transducers in a plane symmetrical to the horizontal plane.

  16. A High-Frequency Annular-Array Transducer Using an Interdigital Bonded 1-3 Composite

    PubMed Central

    Chabok, Hamid Reza; Cannata, Jonathan M.; Kim, Hyung Ham; Williams, Jay A.; Park, Jinhyoung; Shung, K. Kirk

    2011-01-01

    This paper reports the design, fabrication, and characterization of a 1–3 composite annular-array transducer. An interdigital bonded (IB) 1–3 composite was prepared using two IB operations on a fine-grain piezoelectric ceramic. The final composite had 19-μm-wide posts separated by 6-μm-wide polymer kerfs. A novel method to remove metal electrodes from polymer portions of the 1–3 composite was established to eliminate the need for patterning and aligning the electrode on the composite to the electrodes on a flexible circuit. Unloaded epoxy was used for both the matching and backing layers and a flexible circuit was used for interconnect. A prototype array was successfully fabricated and tested. The results were in reasonable agreement with those predicted by a circuit-analogous model. The average center frequency estimated from the measured pulse-echo responses of array elements was 33.5 MHz and the −6-dB fractional bandwidth was 57%. The average insertion loss recorded was 14.3 dB, and the maximum crosstalk between the nearest-neighbor elements was less than −37 dB. Images of a wire phantom and excised porcine eye were obtained to show the capabilities of the array for high-frequency ultrasound imaging. PMID:21244988

  17. Thermal-Independent Properties of PIN-PMN-PT Single-Crystal Linear-Array Ultrasonic Transducers

    PubMed Central

    Chen, Ruimin; Wu, Jinchuan; Lam, Kwok Ho; Yao, Liheng; Zhou, Qifa; Tian, Jian; Han, Pengdi; Shung, K. Kirk

    2013-01-01

    In this paper, low-frequency 32-element linear-array ultrasonic transducers were designed and fabricated using both ternary Pb(In1/2Nb1/2)–Pb(Mg1/3Nb2/3)–PbTiO3 (PIN-PMN-PT) and binary Pb(Mg1/3Nb2/3)–PbTiO3 (PMN-PT) single crystals. Performance of the array transducers was characterized as a function of temperature ranging from room temperature to 160°C. It was found that the array transducers fabricated using the PIN-PMN-PT single crystal were capable of satisfactory performance at 160°C, having a −6-dB bandwidth of 66% and an insertion loss of 37 dB. The results suggest that the potential of PIN-PMN-PT linear-array ultrasonic transducers for high-temperature ultrasonic transducer applications is promising. PMID:23221227

  18. Ultrasound cylindrical phased array for transoesophageal thermal therapy: initial studies

    NASA Astrophysics Data System (ADS)

    Melodelima, David; Lafon, Cyril; Prat, Frederic; Birer, Alain; Cathignol, Dominique

    2002-12-01

    This work was undertaken to investigate the feasibility of constructing a cylindrical phased array composed of 64 elements spread around the periphery (OD 10.6 mm) for transoesophageal ultrasound thermotherapy. The underlying operating principle of this applicator is to rotate a plane ultrasound beam electronically. For this purpose, eight adjacent transducers were successively excited with appropriate delay times so as to generate a plane wave. The exposure direction was changed by exciting a different set of eight elements. For these feasibility studies, we used a cylindrical prototype (OD 10.6 mm) composed of 16 elementary transducers distributed over a quarter of the cylinder, all operating at 4.55 MHz. The active part was mechanically reinforced by a rigid damper structure behind the transducers. It was shown that an ultrasound field similar to that emitted by a plane transducer could be generated. Ex vivo experiments on pig's liver demonstrated that the ultrasound beam could be accurately rotated to generate sector-based lesions to a suitable depth (up to 19 mm). Throughout these experiments, exposures lasting 20 s were delivered at an acoustic intensity of 17 W cm-2. By varying the power from exposure to exposure, the depth of the lesion at different angles could be controlled.

  19. Packaging and modular assembly of large-area and fine-pitch 2-D ultrasonic transducer arrays.

    PubMed

    Lin, Der-Song; Wodnicki, Robert; Zhuang, Xuefeng; Woychik, Charles; Thomenius, Kai E; Fisher, Rayette A; Mills, David M; Byun, Albert J; Burdick, William; Khuri-Yakub, Pierre; Bonitz, Barry; Davies, Todd; Thomas, Glen; Otto, Bernd; Töpper, Michael; Fritzsch, Thomas; Ehrmann, Oswin

    2013-07-01

    A promising transducer architecture for largearea arrays employs 2-D capacitive micromachined ultrasound transducer (CMUT) devices with backside trench-frame pillar interconnects. Reconfigurable array (RA) application-specified integrated circuits (ASICs) can provide efficient interfacing between these high-element-count transducer arrays and standard ultrasound systems. Standard electronic assembly techniques such as flip-chip and ball grid array (BGA) attachment, along with organic laminate substrate carriers, can be leveraged to create large-area arrays composed of tiled modules of CMUT chips and interface ASICs. A large-scale, fully populated and integrated 2-D CMUT array with 32 by 192 elements was developed and demonstrates the feasibility of these techniques to yield future large-area arrays. This study demonstrates a flexible and reliable integration approach by successfully combining a simple under-bump metallization (UBM) process and a stacked CMUT/interposer/ASIC module architecture. The results show high shear strength of the UBM (26.5 g for 70-μm balls), high interconnect yield, and excellent CMUT resonance uniformity (s = 0.02 MHz). A multi-row linear array was constructed using the new CMUT/interposer/ASIC process using acoustically active trench-frame CMUT devices and mechanical/ nonfunctional Si backside ASICs. Imaging results with the completed probe assembly demonstrate a functioning device based on the modular assembly architecture. PMID:25004504

  20. Phase velocity spectrum analysis for a time delay comb transducer for guided wave mode excitation

    SciTech Connect

    Quarry, M J; Rose, J L

    2000-09-26

    A theoretical model for the analysis of ultrasonic guided wave mode excitation of a comb transducer with time delay features was developed. Time delay characteristics are included via a Fourier transform into the frequency domain. The phase velocity spectrum can be used to determine the mode excitation on the phase velocity dispersion curves for a given structure. Experimental and theoretical results demonstrate the tuning of guided wave modes using a time delay comb transducer.

  1. Multiple-frequency phased array patterns for therapeutic ultrasound

    NASA Astrophysics Data System (ADS)

    Ballard, John R.; Liu, Dalong; Casper, Andrew J.; Wan, Yayun; Almekkawy, Mohamed; Ebbini, Emad S.

    2012-10-01

    Modern transducer technology allows for the design and implementation of therapeutic arrays with relatively wide bandwidths (>50%) and low cross coupling between elements. We present results from a 3.5 MHz, 64-element prototype designed for small-animal and superficial therapeutic HIFU applications (Imasonic, Inc.) This transducer has a 58% 6-dB fractional BW average on its elements allowing for therapeutic output in the frequency range of 2.7 - 4.6 MHz. We present a simulation/experimental study to evaluate and optimize the focusing capabilities of the phased array prototype when excited by multiple-frequency components. Preliminary results have shown that multiple-frequency excitation may be beneficial in enhancing the therapeutic effects of HIFU beams. A multiple-focus pattern synthesis algorithm for arrays excited by multiple-frequency signals has been developed and tested using linear pressure field simulations. The algorithm maintains the precise phase relationship between the frequency components at each focal spot to achieve a desirable outcome. Hydrophone measurements to validate the approach show that nonlinear effects at the focal location are more prominent with the frequency mixing compared to conventional single frequency excitation. An in vitro study of lesion formation in freshly excised porcine liver was investigated.

  2. Acoustic Doppler velocity measurement system using capacitive micromachined ultrasound transducer array technology.

    PubMed

    Shin, Minchul; Krause, Joshua S; DeBitetto, Paul; White, Robert D

    2013-08-01

    This paper describes the design, fabrication, modeling, and characterization of a small (1 cm(2) transducer chip) acoustic Doppler velocity measurement system using microelectromechanical systems capacitive micromachined ultrasound transducer (cMUT) array technology. The cMUT sensor has a 185 kHz resonant frequency to achieve a 13° beam width for a 1 cm aperture. A model for the cMUT and the acoustic system which includes electrical, mechanical, and acoustic components is provided. Furthermore, this paper shows characterization of the cMUT sensor with a variety of testing procedures including Laser Doppler Vibrometry (LDV), beampattern measurement, reflection testing, and velocity testing. LDV measurements demonstrate that the membrane displacement at the center point is 0.4 nm/V(2) at 185 kHz. The maximum range of the sensor is 60 cm (30 cm out and 30 cm back). A velocity sled was constructed and used to demonstrate measureable Doppler shifts at velocities from 0.2 to 1.0 m/s. The Doppler shifts agree well with the expected frequency shifts over this range. PMID:23927100

  3. In-flight measurement of ice growth on an airfoil using an array of ultrasonic transducers

    NASA Technical Reports Server (NTRS)

    Hansman, R. John, Jr.; Kirby, Mark S.; Mcknight, Robert C.; Humes, Robert L.

    1987-01-01

    Results from three research flights to obtain in-flight ultrasonic pulse-echo measurements of airfoil ice thickness as a function of time using an array of eight ultrasonic transducers mounted flush with the leading edge of the airfoil are presented. The accuracy of the thickness measurements is found to be within 0.5 mm of mechanical and stereophotograph measurements of the ice accretion. The ultrasonic measurements demonstrate that the ice growth rate typically varies during the flight, with variations in the ice growth rate for dry ice growth being primarily due to fluctuations in the cloud liquid water content. Discrepancies between experimental results and results predicted by an analytic icing code underline the need for a better understanding of the physics of wet ice growth.

  4. Deep Tissue Photoacoustic Imaging Using a Miniaturized 2-D Capacitive Micromachined Ultrasonic Transducer Array

    PubMed Central

    Kothapalli, Sri-Rajasekhar; Ma, Te-Jen; Vaithilingam, Srikant; Oralkan, Ömer

    2014-01-01

    In this paper, we demonstrate 3-D photoacoustic imaging (PAI) of light absorbing objects embedded as deep as 5 cm inside strong optically scattering phantoms using a miniaturized (4 mm × 4 mm × 500 µm), 2-D capacitive micromachined ultrasonic transducer (CMUT) array of 16 × 16 elements with a center frequency of 5.5 MHz. Two-dimensional tomographic images and 3-D volumetric images of the objects placed at different depths are presented. In addition, we studied the sensitivity of CMUT-based PAI to the concentration of indocyanine green dye at 5 cm depth inside the phantom. Under optimized experimental conditions, the objects at 5 cm depth can be imaged with SNR of about 35 dB and a spatial resolution of approximately 500 µm. Results demonstrate that CMUTs with integrated front-end amplifier circuits are an attractive choice for achieving relatively high depth sensitivity for PAI. PMID:22249594

  5. Three-dimensional endoscopic photoacoustic imaging based on multielement linear transducer array

    NASA Astrophysics Data System (ADS)

    Yuan, Yi; Yang, Sihua; Xing, Da

    2011-09-01

    An implementation system of three-dimensional endoscopic photoacoustic imaging is presented. The developed endoscopic photoacoustic detector integrates a multielement linear transducer array, a reflective device, a Plexiglass tube, and ultrasonic coupling medium. To match with the acoustic impendence of Plexiglass tube, a glycerin solution with 45% volume percentage was used as the ultrasonic coupling medium. This ultrasonic coupling medium can decrease photoacoustic pressure transmission loss during the progress of photoacoustic signal propagation. The capability of the system for three-dimensional imaging was verified with chicken breast tissue. Furthermore, pig normal rectal tissue and mouse breast tumor tissue in an ex vivo cavity model were imaged by the system. The reconstructed three-dimensional photoacoustic image presented the structural information of normal and lesion tissue. The experimental results demonstrate the multielement-based endoscopic photoacoustic imaging system with inside-out laser exciting mode has the ability of reconstructing three-dimensional images of biology tissue.

  6. Three-dimensional endoscopic photoacoustic imaging based on multi-element linear transducer array

    NASA Astrophysics Data System (ADS)

    Yuan, Yi; Yang, Sihua; Xing, Da

    2012-03-01

    An implementation system of three-dimensional endoscopic photoacoustic imaging is presented. The developed endoscopic photoacoustic detector integrates a multielement linear transducer array, a reflective device, a Plexiglass tube and ultrasonic coupling medium. To match with the acoustic impendence of Plexiglass tube, a glycerin solution with 45% volume percentage was used as the ultrasonic coupling medium. This ultrasonic coupling medium can decrease photoacoustic pressure transmission loss during the progress of photoacoustic signal propagation. The capability of the system for three-dimensional imaging was verified with chicken breast tissue. The experimental results demonstrate the multielement-based endoscopic photoacoustic imaging system with inside-out laser exciting mode has the ability of reconstructing three-dimensional images of biology tissue.

  7. Three-dimensional endoscopic photoacoustic imaging based on multi-element linear transducer array

    NASA Astrophysics Data System (ADS)

    Yuan, Yi; Yang, Sihua; Xing, Da

    2011-11-01

    An implementation system of three-dimensional endoscopic photoacoustic imaging is presented. The developed endoscopic photoacoustic detector integrates a multielement linear transducer array, a reflective device, a Plexiglass tube and ultrasonic coupling medium. To match with the acoustic impendence of Plexiglass tube, a glycerin solution with 45% volume percentage was used as the ultrasonic coupling medium. This ultrasonic coupling medium can decrease photoacoustic pressure transmission loss during the progress of photoacoustic signal propagation. The capability of the system for three-dimensional imaging was verified with chicken breast tissue. The experimental results demonstrate the multielement-based endoscopic photoacoustic imaging system with inside-out laser exciting mode has the ability of reconstructing three-dimensional images of biology tissue.

  8. Antenna-array, phase quadrature tracking system

    NASA Technical Reports Server (NTRS)

    Cubley, H. D.

    1970-01-01

    Phase relationship between input signals appearing on widely-spaced parallel connected antenna elements in array is automatically adjusted in phase quadrature tracking system. Compact and lightweight design permit use in wide variety of airborne communications networks.

  9. Length mode piezoelectric ultrasonic transducer for inspection of solid objects

    NASA Technical Reports Server (NTRS)

    Thompson, R. B. (Inventor)

    1978-01-01

    The transducer is constructed from individual transducer elements arranged in an array and configured to exhibit a predominant, longitudinal mode transversely to the array. The elements are interconnected through thin flexible sheets. Each element is individually damped, and the transducer as a whole is electrically damped through resonance with the clamped capacitance and dissipation. Electrical control permits inphase operation of all transducer elements or control with preselected phase differences.

  10. A circular array transducer for photoacoustic imaging by using piezoelectric single crystal lead magnesium niobate-lead zirconate titanate

    NASA Astrophysics Data System (ADS)

    Cao, Yonggang; Ha, Kanglyeol; Kim, Moojoon; Kang, Hyunwook; Oh, Jung-Hwan; Kim, Jungsoon

    2015-07-01

    The ultrasound transducers of which center frequencies are lower than 10 MHz are commonly used in low frequency photoacoustic (PA) imaging systems. However, the improvement of their sensitivity is still needed to detect weak PA signals. In this study, a circular array transducer was constructed by using 120 needle hydrophones made of piezoelectric single crystal lead magnesium niobate-lead zirconate titanate (PMN-PZT). The needle hydrophone was designed to have high sensitivity and wide bandwidth through the Krimtholz-Leedom-Matthaei (KLM) simulation of receiving impulse response. The sensitivity of the fabricated PMN-PZT hydrophone was compared with a commercial poly(vinylidene fluoride) (PVDF) needle hydrophone. The usefulness of the circular array transducer was demonstrated by applying it to a PA system for obtaining images.

  11. Large phased-array radars

    SciTech Connect

    Brookner, D.E.

    1988-12-15

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

  12. Phased Array Inspection of Titanium Disk Forgings Targeting no. 1/2 FBH Sensitivity

    SciTech Connect

    Roberts, R.A.; Friedl, J.

    2005-04-09

    The phased array implementation of a focused zoned ultrasonic inspection to achieve a >3dB signal-to-noise for no. 1/2 flat bottom holes (FBH) in titanium is reported. Previous work established the ultrasound focusing required to achieve the targeted sensitivity. This work reports on the design of a phased array transducer capable of maintaining the needed focus to the depths required in the forging inspection. The performance of the phased array inspection is verified by examining signal-to-noise of no. 1/2 FBHs contained in coupons cut from actual forgings.

  13. Handheld Thermoacoustic Scanning System Based on a Linear-array Transducer.

    PubMed

    Ji, Zhong; Ding, Wenzheng; Ye, Fanghao; Lou, Cunguang

    2016-07-01

    To receive the information necessary for imaging, traditional microwave-induced thermoacoustic imaging systems (MITISs) use a type of circular-scanning mode using single or arc detectors. However, the use of MITISs for body scanning is complicated by restrictions in space and imaging time. A linear-array detector, the most widely used transducer in medical ultrasound imaging systems for body scanning, is a possible alternative to MITISs for scanning biological tissues, such as from the breast or limbs. In this paper, a handheld MITIS, based on a linear-array detector and a multiple data acquisition system, is described, and the capacity of the system is explored experimentally. First, the vertical and lateral resolution of the system is discussed. Next, real-time imaging of a moving object, obtained with an image capture rate of 20 frame/s, is described. Finally, a phantom experiment is detailed, investigating the overall imaging capability. The results show that this system achieves rapid scanning with a large field of view. The system has the obvious advantages of being handheld, not using coupled fluids, and achieving real-time imaging with a large field of view, which make this MITIS more suitable for clinical applications. PMID:26294659

  14. Ultrasound nondestructive evaluation (NDE) imaging with transducer arrays and adaptive processing.

    PubMed

    Li, Minghui; Hayward, Gordon

    2012-01-01

    This paper addresses the challenging problem of ultrasonic non-destructive evaluation (NDE) imaging with adaptive transducer arrays. In NDE applications, most materials like concrete, stainless steel and carbon-reinforced composites used extensively in industries and civil engineering exhibit heterogeneous internal structure. When inspected using ultrasound, the signals from defects are significantly corrupted by the echoes form randomly distributed scatterers, even defects that are much larger than these random reflectors are difficult to detect with the conventional delay-and-sum operation. We propose to apply adaptive beamforming to the received data samples to reduce the interference and clutter noise. Beamforming is to manipulate the array beam pattern by appropriately weighting the per-element delayed data samples prior to summing them. The adaptive weights are computed from the statistical analysis of the data samples. This delay-weight-and-sum process can be explained as applying a lateral spatial filter to the signals across the probe aperture. Simulations show that the clutter noise is reduced by more than 30 dB and the lateral resolution is enhanced simultaneously when adaptive beamforming is applied. In experiments inspecting a steel block with side-drilled holes, good quantitative agreement with simulation results is demonstrated. PMID:22368457

  15. CDS solid state phase insensitive ultrasonic transducer. [annealing dadmium sulfide crystals

    NASA Technical Reports Server (NTRS)

    Heyman, J. S. (Inventor)

    1980-01-01

    A phase insensitive ultrasonic transducer which includes a CdS crystal that is annealed for a selected period of time and at a selected temperature to provide substantially maximum acoustic attenuation at the operating frequency of the transducer is described. Two electrodes are attached to the crystal with amplifier means and a signal processing system connected to one of the electrodes to provide an ultrasonic receiver.

  16. Ultrasonic Phased Array Inspection of Seeded Titanium Billet

    NASA Astrophysics Data System (ADS)

    Friedl, J. H.; Gray, T. A.; Khandelwal, P.; Dunhill, T.

    2004-02-01

    As part of efforts by Rolls-Royce to evaluate the use of ultrasonic phased arrays for inspection of titanium billets, a series of ultrasonic phased array inspections were performed at the Center for Nondestructive Evaluation (CNDE). The inspections were performed using a sectorial-annular array designed especially for titanium billets by R/D Tech and supplied to Rolls-Royce. The billet test piece is seeded with thirteen yttria disks, each located at successive depths below the outer diameter surface to just past the billet centerline. The phased array inspections employed both fixed-focus and dynamic-depth-focus (DDF) focal laws in conjunction with several depth gating schemes. Aperture and focal parameters were changed as a function of depth when using fixed-focus focal laws. Results include characterization of transducer performance and delay-time correction of imperfections, signal-to-noise measurements for the yttria disks in the billet test piece, and effects of probe misalignment on flaw sensitivity.

  17. Airborne Electronically Steerable Phased Array (AESPA) program

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The basic concept and design of a flatplate-fed transmission array are described and system performance requirements are summarized. Particular emphasis is given to the design of the aperture, the radiating element, the phase shifter, the flatplate feed, and the mechanical support structure. Fabrication and testing techniques are considered. Of the three major parameters of interest in demonstrating the performance capabilities of the transmissive array, beamwidth was shown to be the least sensitive to system amplitude and phase errors. Beam pointing angle was also shown to be relatively insensitive to errors. Close agreement between measured and calculated values was found for array gain. The greatest difference was found for array sidelone level.

  18. Nanomaterial-based biosensors using dual transducing elements for solution phase detection.

    PubMed

    Li, Ning; Su, Xiaodi; Lu, Yi

    2015-05-01

    Biosensors incorporating nanomaterials have demonstrated superior performance compared to their conventional counterparts. Most reported sensors use nanomaterials as a single transducer of signals, while biosensor designs using dual transducing elements have emerged as new approaches to further improve overall sensing performance. This review focuses on recent developments in nanomaterial-based biosensors using dual transducing elements for solution phase detection. The review begins with a brief introduction of the commonly used nanomaterial transducers suitable for designing dual element sensors, including quantum dots, metal nanoparticles, upconversion nanoparticles, graphene, graphene oxide, carbon nanotubes, and carbon nanodots. This is followed by the presentation of the four basic design principles, namely Förster Resonance Energy Transfer (FRET), Amplified Fluorescence Polarization (AFP), Bio-barcode Assay (BCA) and Chemiluminescence (CL), involving either two kinds of nanomaterials, or one nanomaterial and an organic luminescent agent (e.g. organic dyes, luminescent polymers) as dual transducers. Biomolecular and chemical analytes or biological interactions are detected by their control of the assembly and disassembly of the two transducing elements that change the distance between them, the size of the fluorophore-containing composite, or the catalytic properties of the nanomaterial transducers, among other property changes. Comparative discussions on their respective design rules and overall performances are presented afterwards. Compared with the single transducer biosensor design, such a dual-transducer configuration exhibits much enhanced flexibility and design versatility, allowing biosensors to be more specifically devised for various purposes. The review ends by highlighting some of the further development opportunities in this field. PMID:25763412

  19. Coplanar waveguide fed phased array antenna

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Ponchak, George E.; Lee, R. Q.; Fernandez, N. S.

    1990-01-01

    A K-band four element linear phased array was designed and tested. Coplanar waveguide (CPW) is used for the microwave distribution system. A CPW to twin strip transition is used to interface with the printed dipole antennas. MMIC phased shifters are used for phase control.

  20. A phased array tracking antenna for vehicles

    NASA Technical Reports Server (NTRS)

    Ohmori, Shingo; Mano, Kazukiko; Tanaka, Kenji; Matsunaga, Makoto; Tsuchiya, Makio

    1990-01-01

    An antenna system including antenna elements and a satellite tracking method is considered a key technology in implementing land mobile satellite communications. In the early stage of land mobile satellite communications, a mechanical tracking antenna system is considered the best candidate for vehicles, however, a phased array antenna will replace it in the near future, because it has many attractive advantages such as a low and compact profile, high speed tracking, and potential low cost. Communications Research Laboratory is now developing a new phased array antenna system for land vehicles based on research experiences of the airborne phased array antenna, which was developed and evaluated in satellite communication experiments using the ETS-V satellite. The basic characteristics of the phased array antenna for land vehicles are described.

  1. Monitoring of high-intensity focused ultrasound treatment by shear wave elastography induced by two-dimensional-array therapeutic transducer

    NASA Astrophysics Data System (ADS)

    Iwasaki, Ryosuke; Takagi, Ryo; Nagaoka, Ryo; Jimbo, Hayato; Yoshizawa, Shin; Saijo, Yoshifumi; Umemura, Shin-ichiro

    2016-07-01

    Shear wave elastography (SWE) is expected to be a noninvasive monitoring method of high-intensity focused ultrasound (HIFU) treatment. However, conventional SWE techniques encounter difficulty in inducing shear waves with adequate displacements in deep tissue. To observe tissue coagulation at the HIFU focal depth via SWE, in this study, we propose using a two-dimensional-array therapeutic transducer for not only HIFU exposure but also creating shear sources. The results show that the reconstructed shear wave velocity maps detected the coagulated regions as the area of increased propagation velocity even in deep tissue. This suggests that “HIFU-push” shear elastography is a promising solution for the purpose of coagulation monitoring in deep tissue, because push beams irradiated by the HIFU transducer can naturally reach as deep as the tissue to be coagulated by the same transducer.

  2. Phased array beamforming using nonlinear oscillators

    NASA Astrophysics Data System (ADS)

    Gabbay, Michael; Larsen, Michael L.; Tsimring, Lev S.

    2004-10-01

    We describe a concept in which an array of coupled nonlinear oscillators is used for beamforming in phased array receivers. The signal that each sensing element receives, beam steered by time delays, is input to a nonlinear oscillator. The nonlinear oscillators for each element are in turn coupled to each other. For incident signals sufficiently close to the steering angle, the oscillator array will synchronize to the forcing signal whereas more obliquely incident signals will not induce synchronization. The beam pattern that results can show a narrower mainlobe and lower sidelobes than the equivalent conventional linear beamformer. We present a theoretical analysis to explain the beam pattern of the nonlinear oscillator array.

  3. Fabrication and Evaluation of Fully-Sampled, Two-Dimensional Transducer Array for “Sonic Window” Imaging System

    PubMed Central

    Eames, Matthew D.C.; Hossack, John A.

    2008-01-01

    A low-cost, fully-sampled, 3600 element 2D transducer array operating at 5 MHz and designed for use in a hand-held ultrasound system is described here. Four array configurations are presented – 1. array with both matching and pedestal backing layers, 2. array with a matching layer but no backing pedestal, 3. array with a backing pedestal but no matching layer, and 4. array with neither matching layer nor backing pedestal. Each array was characterized in terms of impedance measurements, pulse-echo response, and experimental beamprofile. Comparative finite element analysis simulations are also presented. Average estimated active element yield for the four arrays was 94%. The array with pedestal layer proved the most promising, providing a 26 % bandwidth and a 1.7 dB improvement in sensitivity with respect to the array with neither pedestal nor matching layer. Although this bandwidth is acceptable for our specific application (C-scan imaging), reverberations within the substrate material remain a potential challenge. We are currently working to fabricate a custom PCB material to address this concern, and may also consider using a pre-compensated transmit waveform or matched digital filter approach to further reduce the effects of such reverberations. PMID:18490042

  4. Phase interpolation circuits using frequency multiplication for phased arrays

    NASA Technical Reports Server (NTRS)

    Caron, P. R.; Mailloux, R. J.

    1970-01-01

    Antenna phasing circuit is described with the following advantages - 1/ increased number of phased elements, 2/ current repetition for each array element, 3/ circuit simplicity, and 4/ accurate phase interpolation. This circuit functions with Huggins Scan or with nearly any other phasing system.

  5. In vivo mouse brain tomography by fast dual-scanning photoacoustic imaging system based on array transducer

    NASA Astrophysics Data System (ADS)

    Yang, Sihua; Xing, Da

    2008-12-01

    A full-view photoacoustic tomography system with dual-scanning using a linear transducer array for fast imaging of complicated blood network was developed. In this system, a 128-element linear transducer array was used to detect photoacoustic signals by combined scanning of electronic scan and mechanical scan. An improved limited-field filtered back projection algorithm with directivity factors was applied to reconstruct the distribution of the absorbed optical energy deposit. An in vivo experiment on a mouse brain was performed to evaluate the ability of this composite system. A clear view of the cerebrovascular network on the brain cortex was acquired successfully. Furthermore, the reconstruct images with different number of scanning positions were also investigated and analyzed to induce a compromised proposal between scanning time and scanning number. The experimental results demonstrate the multi-element photoacoustic imaging system has the potential to acquire the time-resolved functional information for fundamental research of small animal brain imaging.

  6. Radiometric stability of Phase 3 WISP arrays

    NASA Astrophysics Data System (ADS)

    Flynn, David S.; Marlow, Steven A.; Bergin, Thomas P.; Murrer, Robert Lee

    2000-07-01

    Phase 3 WISP arrays and BRITE arrays are currently being used extensively in many projection systems in many different facilities. These arrays have not been annealed at the factory, and previous tests with the arrays have revealed instabilities in the radiometric output when the arrays are driven at higher voltages. In some applications, the instabilities can be avoided by operating the arrays at lower voltages. In many KHILS applications, it is desirable to drive the arrays with the highest possible voltages to simulate hot missile targets. In one KHILS application (the KHILS VAcuum Cold Chamber, KVACC), the arrays are cooled to near cryogenic temperatures and then driven to high voltages. At lower substrate temperatures, the characteristic responses of the emitters change. Thus, it is important that the response and the stability of the radiometric output of the arrays be well understood for various substrate temperatures, and that the arrays either be annealed or operated below the voltage where the emitters begin to anneal. KHILS has investigated annealing procedures in the past, but there was concern that the annealing procedures themselves -- driving the arrays at high voltages for long times -- would damage the arrays. In order to understand the performance of the arrays better, and to reduce risks associated with driving the arrays at high voltages and operating the arrays at low substrate temperatures, a systematic measurement program was initiated. The radiometric output of new Phase 3 WISP arrays was accurately measured as a function of voltage and time. Arrays designated for testing were driven to the higher voltages and the radiometric output was measured for as long as two hours. Curves indicative of the annealing were observed, and it was determined that the maximum stable output without annealing was about 500 K (MWIR apparent temperature). Blocks of emitters were annealed and tested again. It was determined that stable output of as much as 680 K

  7. A cylindrical-section ultrasound phased-array applicator for hyperthermia cancer therapy.

    PubMed

    Ebbini, E S; Umemura, S I; Ibbini, M; Cain, C A

    1988-01-01

    A phased-array applicator geometry for deep localized hyperthermia is presented. The array consists of rectangular transducer elements forming a section of a cylinder that conforms to the body portals in the abdominal and pelvic regions. Focusing and scanning properties of the cylindrical-section array are investigated in homogeneous lossy media using appropriate computer simulations. The characteristic focus of this array is shown to be spatially limited in both transverse and longitudinal directions with intensity gain values suitable for deep hyperthermia applications. The ability of the cylindrical-section phased array to generate multiple foci using the field conjugation method is examined. The effect of the grating lobes on the power deposition pattern of the scanned field is shown to be minimal. Steady-state temperature distributions are simulated using a three-dimensional thermal model of the normal tissue layers surrounding a tumor of typical volume. The advantages and the limitations of this array configuration are discussed. PMID:18290188

  8. Methods for Characterizing the System Functions of Ultrasonic Linear Phased Array Inspection Systems

    NASA Astrophysics Data System (ADS)

    Huang, Ruiju; Schmerr, Lester W.

    2008-02-01

    This work characterizes all the electrical and electromechanical aspects of a linear phased array system, using a matrix of system functions that are obtained from the measured response of the array elements in a simple reference experiment. It is shown that for the arrays tested all these system functions are essentially identical, allowing one to use a single system function to characterize the entire array, as done for an ordinary single element transducer. The variation of this single system function with the number of elements firing in the array or with changes of the delay law used is described. It is also demonstrated that once such a single system function is obtained for an array, it can be used in a complete ultrasonic measurement model to accurately predict the array response measured from of a reference reflector in an immersion setup.

  9. RADIATION CHARACTERISTICS OF A GENERALIZED PHASED ARRAY

    NASA Technical Reports Server (NTRS)

    Acosta, R. J.

    1994-01-01

    The phased array has become a key component in the design of advanced antenna systems. This computer program was developed to examine the radiation characteristics of a generalized phased array antenna. Using a very efficient numerical technique, this program calculates the array's radiated power and its directivity. The results can be used to determine the radiation pattern of a generalized phased array at near- or far-field observation points. This program is a key research tool at the NASA Lewis Research Center for analyzing advanced space communication antenna systems. Results from this program compare favorably with experimental Lewis results for arrays of 2x2 and 3x3 elements. Given the array geometry and element characteristics, generalized phased array attributes can be broken into two areas: 1) the power radiated and its directivity at any given point, and 2) the co- and cross-polarization field components. This program allows arbitrarily located source elements with an analytically described cosine pattern. The formulation is based on a Romberg integration scheme and takes into account arbitrary element polarization, E and H plane element patterns, and mutual coupling. The input consists of the array geometry; phase, amplitude, linear and circular polarization of each source element; and the cosine functions of the element pattern. The output is a series of observation angles with their associated field magnitude and polarizations. Total radiated power and peak directivity are also calculated. This program is written in FORTRAN IV for batch execution and has been implemented on an IBM 370 computer operating under TSS with a central memory requirement of approximately 22K of 8 bit bytes. The IBM Scientific Subroutine Package (SSP) is required to run the program. This program was developed in 1986.

  10. Ultrasonic phased array inspection imaging technology for NDT of offshore platform structures

    NASA Astrophysics Data System (ADS)

    Shan, Baohua; Wang, Hua; Liang, Yongning; Duan, Zhongdong; Ou, Jinping

    2008-03-01

    In order to improve inspection result repetition and flaw ration veracity of manual ultrasonic inspection of offshore platform structure, an ultrasonic phased array inspection imaging technology for NDT of offshore platform structures is proposed in this paper. Aimed at the practical requirement of tubular joint welds inspection of offshore platform structures, the ultrasonic phased array inspection imaging system for offshore platform structures is developed, which is composed of computer, ultrasonic circuit system, scanning device, phased array transducer and inspection imaging software system. The experiment of Y shape tubular joint model of 60 degree is performed with the ultrasonic phased array inspection imaging system for offshore platform structures, the flaws characteristic could be exactly estimated and the flaws size could be measured through ultrasonic phased array inspection imaging software system for offshore platform structures. Experiment results show that the ultrasonic phased array inspection imaging technology for offshore platform structures is feasible, the ultrasonic phased array inspection imaging system could detect flaws in tubular joint model, the whole development trend of flaws is factually imaging by the ultrasonic phased array inspection technology of offshore platform structures.

  11. Array Phase Shifters: Theory and Technology

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R.

    2007-01-01

    While there are a myriad of applications for microwave phase shifters in instrumentation and metrology, power combining, amplifier linearization, and so on, the most prevalent use is in scanning phased-array antennas. And while this market continues to be dominated by military radar and tracking platforms, many commercial applications have emerged in the past decade or so. These new and potential applications span low-Earth-orbit (LEO) communications satellite constellations and collision warning radar, an aspect of the Intelligent Vehicle Highway System or Automated Highway System. In any case, the phase shifters represent a considerable portion of the overall antenna cost, with some estimates approaching 40 percent for receive arrays. Ferrite phase shifters continue to be the workhorse in military-phased arrays, and while there have been advances in thin film ferrite devices, the review of this device technology in the previous edition of this book is still highly relevant. This chapter will focus on three types of phase shifters that have matured in the past decade: GaAs MESFET monolithic microwave integrated circuit (MMIC), micro-electromechanical systems (MEMS), and thin film ferroelectric-based devices. A brief review of some novel devices including thin film ferrite phase shifters and superconducting switches for phase shifter applications will be provided. Finally, the effects of modulo 2 phase shift limitations, phase errors, and transient response on bit error rate degradation will be considered.

  12. Design and analysis of an ultrasonic transducer micro-array for near-field imaging of age related macular degeneration

    NASA Astrophysics Data System (ADS)

    Clarke, Clyde C.

    Obtaining quantitative data about tissue has been a goal of ultrasonography since its inception, such data provides invaluable information for diagnosing disease. Traditional ultrasound imaging techniques (B-Mode, C-Mode and M-Mode) have been used to diagnose diseases from images of organs. However, images obtained via these techniques, in some cases, provide limited information about the pathology of the tissues being examined. This is because much of the information that is used for diagnosis depends upon qualitative cues emerging from the echoic profiles of bulk tissue properties. In order to obtain quantitative information about tissue properties, an understanding of the interaction of the ultrasound system proper and tissue is necessary. This requires the creation of detailed models of both the ultrasound imaging system and tissue. These models enable us to obtain quantitative information about tissue, by examining features of backscattered data, generated by the interaction of the ultrasonic imaging system with the tissue under examination. Imaging systems are typically designed with little consideration of the constraints of the imaging environment or the acoustic features of the tissue which include impedance, scatterer size, shape and density. We propose to take into account the physical properties of tissue in designing ultrasonic imaging arrays. We develop a framework for designing ultrasonic imaging systems (primarily the transducer and transducer array) with physical parameters that are tuned to detect specific features of tissue. The design methodology obtains the parameters of an NxN transducer array constrained to a size of e.g. 2mm x 2mm (the size required for medical imaging). The physical parameters of the transducer elements are also obtained for capacitive micromachined ultrasonic transducer (cMUT) technology. In addition to the overall size constraints (2 mm x 2 mm), several other constraints put limitation upon the possible system

  13. MMIC Phased Array Demonstrations with ACTS

    NASA Technical Reports Server (NTRS)

    Raquet, Charles A. (Compiler); Martzaklis, Konstantinos (Compiler); Zakrajsek, Robert J. (Compiler); Andro, Monty (Compiler); Turtle, John P.

    1996-01-01

    Over a one year period from May 1994 to May 1995, a number of demonstrations were conducted by the NASA Lewis Research Center (LeRC) in which voice, data, and/or video links were established via NASA's advanced communications technology satellite (ACTS) between the ACTS link evaluation terminal (LET) in Cleveland, OH, and aeronautical and mobile or fixed Earth terminals having monolithic microwave integrated circuit (MMIC) phased array antenna systems. This paper describes four of these. In one, a duplex voice link between an aeronautical terminal on the LeRC Learjet and the ACTS was achieved. Two others demonstrated duplex voice (and in one case video as well) links between the ACTS and an Army vehicle. The fourth demonstrated a high data rate downlink from ACTS to a fixed terminal. Array antenna systems used in these demonstrations were developed by LeRC and featured LeRC and Air Force experimental arrays using gallium arsenide MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The single 30 GHz transmit array was developed by NASA/LeRC and Texas Instruments. The three 20 GHz receive arrays were developed in a cooperative effort with the Air Force Rome Laboratory, taking advantage of existing Air Force array development contracts with Boeing and Lockheed Martin. The paper describes the four proof-of-concept arrays and the array control system. The system configured for each of the demonstrations is described, and results are discussed.

  14. Phased-array-fed antenna configuration study, volume 2

    NASA Technical Reports Server (NTRS)

    Sorbello, R. M.; Zaghloul, A. I.; Lee, B. S.; Siddiqi, S.; Geller, B. D.

    1983-01-01

    Increased capacity in future satellite systems can be achieved through antenna systems which provide multiplicity of frequency reuses at K sub a band. A number of antenna configurations which can provide multiple fixed spot beams and multiple independent spot scanning beams at 20 GHz are addressed. Each design incorporates a phased array with distributed MMIC amplifiers and phasesifters feeding a two reflector optical system. The tradeoffs required for the design of these systems and the corresponding performances are presented. Five final designs are studied. In so doing, a type of MMIC/waveguide transition is described, and measured results of the breadboard model are presented. Other hardware components developed are described. This includes a square orthomode transducer, a subarray fed with a beamforming network to measure scanning performance, and another subarray used to study mutual coupling considerations. Discussions of the advantages and disadvantages of the final design are included.

  15. Automated Array Assembly, Phase 2

    NASA Technical Reports Server (NTRS)

    Carbajal, B. G.

    1979-01-01

    The solar cell module process development activities in the areas of surface preparation are presented. The process step development was carried out on texture etching including the evolution of a conceptual process model for the texturing process; plasma etching; and diffusion studies that focused on doped polymer diffusion sources. Cell processing was carried out to test process steps and a simplified diode solar cell process was developed. Cell processing was also run to fabricate square cells to populate sample minimodules. Module fabrication featured the demonstration of a porcelainized steel glass structure that should exceed the 20 year life goal of the low cost silicon array program. High efficiency cell development was carried out in the development of the tandem junction cell and a modification of the TJC called the front surface field cell. Cell efficiencies in excess of 16 percent at AM1 have been attained with only modest fill factors. The transistor-like model was proposed that fits the cell performance and provides a guideline for future improvements in cell performance.

  16. Manipulating Liquids With Acoustic Radiation Pressure Phased Arrays

    NASA Technical Reports Server (NTRS)

    Oeftering, Richard C.

    1999-01-01

    High-intensity ultrasound waves can produce the effects of "Acoustic Radiation Pressure" (ARP) and "acoustic streaming." These effects can be used to propel liquid flows and to apply forces that can be used to move or manipulate floating objects or liquid surfaces. NASA's interest in ARP includes the remote-control agitation of liquids and the manipulation of bubbles and drops in liquid experiments and propellant systems. A high level of flexibility is attained by using a high-power acoustic phased array to generate, steer, and focus a beam of acoustic waves. This is called an Acoustic Radiation Pressure Phased Array, or ARPPA. In this approach, many acoustic transducer elements emit wavelets that converge into a single beam of sound waves. Electronically coordinating the timing, or "phase shift," of the acoustic waves makes it possible to form a beam with a predefined direction and focus. Therefore, a user can direct the ARP force at almost any desired point within a liquid volume. ARPPA lets experimenters manipulate objects anywhere in a test volume. This flexibility allow it to be used for multiple purposes, such as to agitate liquids, deploy and manipulate drops or bubbles, and even suppress sloshing in spacecraft propellant tanks.

  17. On the steering of sound energy through a supercritical plate by a near-field transducer array.

    PubMed

    Anderson, Brian E; Hughes, W Jack; Hambric, Stephen A

    2008-05-01

    The ability to direct sound energy through the flexural vibrations of a submerged plate at various angles of incidence using a near-field transducer array is investigated. An alumina bar is placed in front of a one-dimensional, eight-element transducer array, between the array and the water. Operating in a receive mode, data were taken as a function of angle of incidence and compared to data taken without the presence of the alumina bar. The array was also operated in transmit mode and results were compared to corresponding receive mode data, showing that reciprocity holds. Results show that in fact sound energy can be steered through a plate, and that the measurement method used provides a convenient method of measuring the angular dependence of transmission through a plate, including measurements at frequencies above the plate's critical frequency. Experimental results of sound transmission versus angle of incidence of finite sized plates agree qualitatively with theoretical results from an analysis of the transmission through an unbounded flexible partition. PMID:18529181

  18. A Flexible Ultrasound Transducer Array with Micro-Machined Bulk PZT

    PubMed Central

    Wang, Zhe; Xue, Qing-Tang; Chen, Yuan-Quan; Shu, Yi; Tian, He; Yang, Yi; Xie, Dan; Luo, Jian-Wen; Ren, Tian-Ling

    2015-01-01

    This paper proposes a novel flexible piezoelectric micro-machined ultrasound transducer, which is based on PZT and a polyimide substrate. The transducer is made on the polyimide substrate and packaged with medical polydimethylsiloxane. Instead of etching the PZT ceramic, this paper proposes a method of putting diced PZT blocks into holes on the polyimide which are pre-etched. The device works in d31 mode and the electromechanical coupling factor is 22.25%. Its flexibility, good conformal contacting with skin surfaces and proper resonant frequency make the device suitable for heart imaging. The flexible packaging ultrasound transducer also has a good waterproof performance after hundreds of ultrasonic electric tests in water. It is a promising ultrasound transducer and will be an effective supplementary ultrasound imaging method in the practical applications. PMID:25625905

  19. A flexible ultrasound transducer array with micro-machined bulk PZT.

    PubMed

    Wang, Zhe; Xue, Qing-Tang; Chen, Yuan-Quan; Shu, Yi; Tian, He; Yang, Yi; Xie, Dan; Luo, Jian-Wen; Ren, Tian-Ling

    2015-01-01

    This paper proposes a novel flexible piezoelectric micro-machined ultrasound transducer, which is based on PZT and a polyimide substrate. The transducer is made on the polyimide substrate and packaged with medical polydimethylsiloxane. Instead of etching the PZT ceramic, this paper proposes a method of putting diced PZT blocks into holes on the polyimide which are pre-etched. The device works in d31 mode and the electromechanical coupling factor is 22.25%. Its flexibility, good conformal contacting with skin surfaces and proper resonant frequency make the device suitable for heart imaging. The flexible packaging ultrasound transducer also has a good waterproof performance after hundreds of ultrasonic electric tests in water. It is a promising ultrasound transducer and will be an effective supplementary ultrasound imaging method in the practical applications. PMID:25625905

  20. Progress in Ring Array Transducers for Real-Time 3D Ultrasound Guidance of Cardiac Interventional Devices

    PubMed Central

    Light, Edward D.; Lieu, Victor; Suhocki, Paul; Wolf, Patrick D.; Smith, Stephen W.

    2012-01-01

    As a treatment for aortic stenosis, several companies have recently introduced prosthetic heart valves designed to be deployed through a catheter using an intravenous or trans-apical approach. This procedure can either take the place of open heart surgery with some of the devices, or delay it with others. Real-time 3D ultrasound could enable continuous monitoring of these structures before, during and after deployment. We have developed a 2D ring array integrated with a 30 French catheter that is used for trans-apical prosthetic heart valve implantation. The transducer array was built using three 46 cm long flex circuits from MicroConnex (Snoqualmie, WA) which terminate in an interconnect that plugs directly into our system cable, thus no cable soldering is required. This transducer consists of 210 elements at .157 mm inter-element spacing and operates at 5 MHz. Average measured element bandwidth was 26% and average round-trip 50 Ohm insertion loss was -81.1 dB. The transducer were wrapped around the 1 cm diameter lumen of a heart valve deployment catheter. Prosthetic heart valve images were obtained in water tank studies. PMID:21842583

  1. Simulation of Transrib HIFU Propagation and the Strategy of Phased-array Activation

    NASA Astrophysics Data System (ADS)

    Zhou, Yufeng; Wang, Mingjun

    Liver ablation is challenging in high-intensity focused ultrasound (HIFU) because of the presence of ribs and great inhomogeneity in multi-layer tissue. In this study, angular spectrum approach (ASA) has been used in the wave propagation from phased-array HIFU transducer, and diffraction, attenuation and the nonlinearity are accounted for by means of second order operator splitting method. Bioheat equation is used to simulate the subsequent temperature elevation and lesion formation with the formation of shifted focus and multiple foci. In summary, our approach could simulate the performance of phased-array HIFU in the clinics and then develop an appropriate treatment plan.

  2. Ka-Band Phased Array System Characterization

    NASA Technical Reports Server (NTRS)

    Acosta, R.; Johnson, S.; Sands, O.; Lambert, K.

    2001-01-01

    Phased Array Antennas (PAAs) using patch-radiating elements are projected to transmit data at rates several orders of magnitude higher than currently offered with reflector-based systems. However, there are a number of potential sources of degradation in the Bit Error Rate (BER) performance of the communications link that are unique to PAA-based links. Short spacing of radiating elements can induce mutual coupling between radiating elements, long spacing can induce grating lobes, modulo 2 pi phase errors can add to Inter Symbol Interference (ISI), phase shifters and power divider network introduce losses into the system. This paper describes efforts underway to test and evaluate the effects of the performance degrading features of phased-array antennas when used in a high data rate modulation link. The tests and evaluations described here uncover the interaction between the electrical characteristics of a PAA and the BER performance of a communication link.

  3. Reverse Phase Protein Arrays for Compound Profiling.

    PubMed

    Moerke, Nathan; Fallahi-Sichani, Mohammad

    2016-01-01

    Reverse phase protein arrays (RPPAs), also called reverse phase lysate arrays (RPLAs), involve immobilizing cell or tissue lysates, in small spots, onto solid supports which are then probed with primary antibodies specific for proteins or post-translational modifications of interest. RPPA assays are well suited for large-scale, high-throughput measurement of protein and PTM levels in cells and tissues. RPPAs are affordable and highly multiplexable, as a large number of arrays can readily be produced in parallel and then probed separately with distinct primary antibodies. This article describes a procedure for treating cells and preparing cell lysates, as well as a procedure for generating RPPAs using these lysates. A method for probing, imaging, and analyzing RPPAs is also described. These procedures are readily adaptable to a wide range of studies of cell signaling in response to drugs and other perturbations. © 2016 by John Wiley & Sons, Inc. PMID:27622568

  4. Plane wave imaging using phased array

    NASA Astrophysics Data System (ADS)

    Volker, Arno

    2014-02-01

    Phased arrays are often used for rapid inspections. Phased arrays can be used to synthesize different wave fronts. For imaging, focused wave fronts are frequently used. In order to build an image, the phased array has to be fired multiple times at the same location. Alternatively, different data acquisition configurations can be designed in combination with an imaging algorithm. The objective of this paper is to use the minimal amount of data required to construct an image. If a plane wave is synthesized, the region of interest is illuminated completely. For plane wave synthesis, all elements in the phase array are fired. This ensures a good signal to noise ratio. Imaging can be performed efficiently with a mapping algorithm in the wavenumber domain. The algorithm involves only two Fourier transforms and can therefore be extremely fast. The obtained resolution is comparable to conventional imaging algorithms. This work investigates the potential and limitations of this mapping algorithm on simulated data. With this approach, frame rates of more than 1 kHz can be achieved.

  5. An investigation of various shading (window) functions by printing the shape of the function on underwater transmitting transducers and arrays

    NASA Astrophysics Data System (ADS)

    Nicolaides, K.; Nortman, L.

    2012-05-01

    In any sonar system, suppression of the side lobes results in an increase in main beam to side lobe level (signal to noise) ratio, with a consequence in an increase in detection range and resolution. Traditionally, this undertaking is done as part of the signal processing operation of the array. The overall aim of this paper is to investigate the advantages and disadvantages of implementing various shading functions directly on the radiating surface of the individual elements (transducers) of a line array. In particular, this paper examines the performance of various shading (window) functions, such as rectangular, cosine, triangular, Hamming, and Blackman-Harris, by printing the actual shape of the function on a transmitting multi-element line array. The transducers used are of 1-3 piezocomposite material with acoustic window and operate at 300 kHz with over 100 kHz of bandwidth. The results of the acoustic tests and polar (directivity) responses are presented and compared to theoretical simulations. The results obtained show that significant improvement of the main beam to side lobe level ratio can be achieved with an unfortunate widening of the main beam.

  6. Ultrasonic fingerprint sensor using a piezoelectric micromachined ultrasonic transducer array integrated with complementary metal oxide semiconductor electronics

    SciTech Connect

    Lu, Y.; Fung, S.; Wang, Q.; Horsley, D. A.; Tang, H.; Boser, B. E.; Tsai, J. M.; Daneman, M.

    2015-06-29

    This paper presents an ultrasonic fingerprint sensor based on a 24 × 8 array of 22 MHz piezoelectric micromachined ultrasonic transducers (PMUTs) with 100 μm pitch, fully integrated with 180 nm complementary metal oxide semiconductor (CMOS) circuitry through eutectic wafer bonding. Each PMUT is directly bonded to a dedicated CMOS receive amplifier, minimizing electrical parasitics and eliminating the need for through-silicon vias. The array frequency response and vibration mode-shape were characterized using laser Doppler vibrometry and verified via finite element method simulation. The array's acoustic output was measured using a hydrophone to be ∼14 kPa with a 28 V input, in reasonable agreement with predication from analytical calculation. Pulse-echo imaging of a 1D steel grating is demonstrated using electronic scanning of a 20 × 8 sub-array, resulting in 300 mV maximum received amplitude and 5:1 contrast ratio. Because the small size of this array limits the maximum image size, mechanical scanning was used to image a 2D polydimethylsiloxane fingerprint phantom (10 mm × 8 mm) at a 1.2 mm distance from the array.

  7. A photoacoustic imaging system employing a curved-phased ultrasonic array and parallel electronics

    NASA Astrophysics Data System (ADS)

    Maurudis, Anastasios; Huang, Fei; Guo, Puyun; Yan, Shikui; Castillo, Diego; Wang, Lihong V.; Zhu, Quing

    2006-02-01

    Real-time photoacoustic imaging requires ultrasonic array receivers and parallel data acquisition systems for the simultaneous detection of weak photoacoustic signals. In this paper, we introduce a newly completed ultrasonic receiving array system and report preliminary results of our measured point spread function. The system employs a curved ultrasonic phased array consisting of 128-elements, which span a quarter of a complete circle. The center frequency of the array is 5 MHz and the bandwidth is greater than 60%. In order to maximize the signal-to-noise ratio for photoacoustic signal detection, we utilized special designs for the analog front-end electronics. First, the 128 transducer-element signals were routed out using a 50-Ohm impedance matching PCB board to sustain signal integrity. We also utilize 128 low-noise pre-amplifiers, connected directly to the ultrasonic transducer, to amplify the weak photoacoustic signals before they were multiplexed to a variable-gain multi-stage amplifier chain. All front-end circuits were placed close to the transducer array to minimize signal lose due to cables and therefore improve the signal-to-noise ratio. Sixteen analog-to-digital converters were used to sample signals at a rate of 40 mega-samples per second with a resolution of 10-bits per sample. This allows us to perform a complete electronic scan of all 128 elements using just eight laser pulses.

  8. Phased array antenna matching: Simulation and optimization of a planar phased array of circular waveguide elements

    NASA Technical Reports Server (NTRS)

    Dudgeon, J. E.

    1972-01-01

    A computerized simulation of a planar phased array of circular waveguide elements is reported using mutual coupling and wide angle impedance matching in phased arrays. Special emphasis is given to circular polarization. The aforementioned computer program has as variable inputs: frequency, polarization, grid geometry, element size, dielectric waveguide fill, dielectric plugs in the waveguide for impedance matching, and dielectric sheets covering the array surface for the purpose of wide angle impedance matching. Parameter combinations are found which produce reflection peaks interior to grating lobes, while dielectric cover sheets are successfully employed to extend the usable scan range of a phased array. The most exciting results came from the application of computer aided optimization techniques to the design of this type of array.

  9. Wide Angle Liquid Crystal Optical Phased Array

    NASA Technical Reports Server (NTRS)

    Wang, Xing-Hua; Wang, Bin; Bos, Philip J.; Anderson, James E.; Pouch, John J.; Miranda, Felix A.; McManamon, Paul F.

    2004-01-01

    Accurate modeling of a high resolution, liquid crystal (LC) based, optical phased array (OPA) is shown. The simulation shows excellent agreement with a test 2-D LC OPA. The modeling method is extendable to cases where the array element size is close to the wavelength of light. The fringing fields of such a device are first studied, and subsequently reduced. This results in a device that demonstrates plus or minus 7.4 degrees of continuous beam steering at a wavelength of 1550 nm, and a diffraction efficiency (DE) higher than 72%.

  10. Phased array compaction cell for measurement of the transversely isotropic elastic properties of compacting sediments

    SciTech Connect

    Nihei, K.T.; Nakagawa, S.; Reverdy, F.; Meyer, L.R.; Duranti, L.; Ball, G.

    2010-12-15

    Sediments undergoing compaction typically exhibit transversely isotropic (TI) elastic properties. We present a new experimental apparatus, the phased array compaction cell, for measuring the TI elastic properties of clay-rich sediments during compaction. This apparatus uses matched sets of P- and S-wave ultrasonic transducers located along the sides of the sample and an ultrasonic P-wave phased array source, together with a miniature P-wave receiver on the top and bottom ends of the sample. The phased array measurements are used to form plane P-waves that provide estimates of the phase velocities over a range of angles. From these measurements, the five TI elastic constants can be recovered as the sediment is compacted, without the need for sample unloading, recoring, or reorienting. This paper provides descriptions of the apparatus, the data processing, and an application demonstrating recovery of the evolving TI properties of a compacting marine sediment sample.

  11. Brazilian Decimetric Array (Phase-I)

    NASA Astrophysics Data System (ADS)

    Sawant, H. S.; Ramesh, R.; Cecatto, J. R.; Faria, C.; Fernandes, F. C. R.; Rosa, R. R.; Andrade, M. C.; Stephany, S.; Cividanes, L. B. T.; Miranda, C. A. I.; Botti, L. C. L.; Boas, J. W. S. V.; Saito, J. H.; Moron, C. E.; Mascarenhas, N. D.; Subramanian, K. R.; Sundararajan, M. S.; Ebenezer, E.; Sankararaman, M. R.

    2007-05-01

    An East West, one-dimensional radio interferometer array consisting of five parabolic dish antennas has been set up at Cachoeira Paulista (longitude 45°0‧20″ W, latitude 22°41‧19″ S) for observations of the Sun and some of the strong sidereal sources by the Instituto Nacional de Pesquisas Espaciais (INPE), Brazil. This is Phase-I of the proposed Brazilian Decimetric Array and can be operated at any frequency in the range 1.2 1.7 GHz. The instrument has been in operation since November 2004 onwards at 1.6 GHz. The angular and temporal resolutions at this frequency are ˜3‧ and 100 ms, respectively. Details of the array, analog/digital receiver system, and a preliminary East West one-dimensional solar image at the 1.6 GHz are presented in this paper.

  12. Phased array-fed antenna configuration study

    NASA Technical Reports Server (NTRS)

    Crosswell, W. F.; Ball, D. E.; Taylor, R. C.

    1983-01-01

    The scope of this contract entails a configuration study for a phased array fed transmit antenna operating in the frequency band of 17.7 to 20.2 GHz. This initial contract provides a basis for understanding the design limitations and advantages of advanced phased array and cluster feeds (both utilizing intergral MMIC modules) illuminating folded reflector optics (both near field and focused types). Design parametric analyses are performed utilizing as constraints the objective secondary performance requirements of the Advanced Communications Technology Satellite (Table 1.0). The output of the study provides design information which serves as a data base for future active phased array fed antenna studies such as detailed designs required to support the development of a ground tested breadboard. In general, this study is significant because it provides the antenna community with an understanding of the basic principles which govern near field phased scanned feed effects on secondary reflector system performance. Although several articles have been written on analysis procedures and results for these systems, the authors of this report have observed phenomenon of near field antenna systems not previously documented. Because the physical justification for the exhibited performance is provided herein, the findings of this study add a new dimension to the available knowledge of the subject matter.

  13. Synthesized Bistatic Echo Imaging Using Phased Arrays

    NASA Astrophysics Data System (ADS)

    Soumekh, Mehrdad

    1990-01-01

    An object illuminated by a source produces a scattered signal; this signal depends upon both the source and the physical properties of the object. The problem of deducing coordinates, shape and/or certain physical properties of the object from the measurements of the returned signal is an inverse problem called echo imaging. The problem of echo imaging arises in medical imaging, remote sensing (radar; sonar; geophysical exploration), and non-destructive testing. In this paper, we address the problem of imaging an object form its returned signals using a phased array. Our approach is to exploit the array's various radiation patterns and the recordable portion of the returned signal's spectrum to generate the data base for this echo imaging system. Rapid steering of a phased array's radiation patterns can be achieved electronically. These steered waves can be utilized to synthesize waves with varying angles of propagation. In this case, the recorded returned signal for each direction of propagation can be viewed as data obtained by a bistatic array configuration. We first formulate the imaging problem for a plane wave source in a bistatic configuration. We utilize the two-way propagation time and amplitude of the returned signal to relate the object's properties, reflectivity function and coordinates, to the measured data (system modeling). This relationship is the basis for deducing the object's reflectivity function from the recorded data (inverse problem). We then extend these results for an arbitrary radiation pattern and synthesized radiation patterns generated by an array capable of beam steering in cross-range. We show that the recorded returned signals can be related to the spatial frequency contents of the reflectivity function. We also show that these array processing principles can be utilized to formulate a system model and inversion for synthetic aperture radar (SAR) imaging that incorporates wavefront curvature.

  14. Zero-Order Phased Fiber Arrays

    SciTech Connect

    Messerly, M J

    2010-03-22

    Phased arrays remain an important strategy for scaling average power and pulse energy in optical fiber lasers. In zero-order arrays, the lengths of the constituent lasers or amplifiers are matched to within the coherence length of a pulse; for fibers having bandwidths on the order of one nanometer, lengths must be matched to 1 mm; for fiber having bandwidths on the order of 30 nm (pulse duration of 100 fs), lengths must be matched to 30 {micro}m. The overarching goal of this work has been to demonstrate a scaling path to 10 mJ pulses from an array of fiber lasers, with each fiber contributing roughly 1 mJ of energy. The near term goals were, and remain, two-fold. First, to demonstrate that arrays of fiber amplifier chains can be created having path length differences on the order of sub-picoseconds. This has been accomplished, showing that sub-nanojoule, 200 fs pulses can be split into an array of four chains, each chain amplified with a single preamp, and the outputs can be recombined within the coherence length of the pulses. The second near term goal, stabilizing the phase through active feedback, is not yet complete. The strategy has been to generate an out-of-band CW seed signal that is monitored to account for fluctuations in path length that occur between pulses. At this point the necessary hardware is in place, but the control electronics are not. We expect the co-phasing work to continue under separate funding, though in a simpler form. Instead of combining pulses from many amplifiers we would combine many sequential pulses from a single fiber laser via a resonant cavity. Such a scheme is less expensive to build and test (and eventually, to field), though significant technical hurdles must be overcome, including the development of a low-loss mechanism for releasing the energy that is built up within the cavity.

  15. Multi-view Hilbert transformation in full-ring-transducer-array based photoacoustic computed tomography (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Li, Lei; Li, Guo; Zhu, Liren; Xia, Jun; Wang, Lihong V.

    2016-03-01

    Photoacoustic tomography (PAT) exploits optical contrast and ultrasonic detection principles to form images of absorbed optical energy density within tissue. Based on the photoacoustic effect, PAT directly and quantitatively measures specific optical absorption. A full-ring ultrasonic transducer array based photoacoustic computed tomography (PACT) system was recently developed for small animal whole-body imaging with a full-view detection angle and high in-plane resolution (100 µm). However, due to the band-pass frequency response of the piezoelectric transducer elements, the reconstructed images present bipolar (both positive and negative) pixel values, which is artificial and counterintuitive for physicians and biologists seeking to interpret the image. Moreover, bipolar pixel values hinder quantification of physiological parameters, such as oxygen saturation and blood flow speed. Unipolar images can be obtained by deconvolving the raw channel data with the transducer's electrical impulse response and applying non-negativity during iteration, but this process requires complex transducer modeling and time-consuming computation. Here, we present a multi-view Hilbert transformation method to recover the unipolar initial pressure for full-ring PACT. Multi-view Hilbert transformation along the acoustic wave propagation direction minimizes reconstruction artifacts during envelope extraction and maintains the signal-to-noise ratio of the reconstructed images. The in-plane isotropic spatial resolution of this method was quantified to 168 μm within a 20 × 20 mm2 field of view. The effectiveness of the proposed algorithm was first validated by numerical simulations and then demonstrated with ex-vivo mouse brain structural imaging and in-vivo mouse wholebody imaging.

  16. Nonmechanical beam steering using optical phased arrays

    NASA Astrophysics Data System (ADS)

    Dillon, Thomas E.; Schuetz, Christopher A.; Martin, Richard D.; Mackrides, Daniel G.; Curt, Petersen F.; Bonnett, James; Prather, Dennis W.

    2011-11-01

    Beam steering is an enabling technology for establishment of ad hoc communication links, directed energy for infrared countermeasures, and other in-theater defense applications. The development of nonmechanical beam steering techniques is driven by requirements for low size, weight, and power, and high slew rate, among others. The predominant beam steering technology currently in use relies on gimbal mounts, which are relatively large, heavy, and slow, and furthermore create drag on the airframes to which they are mounted. Nonmechanical techniques for beam steering are currently being introduced or refined, such as those based on liquid crystal spatial light modulators; however, drawbacks inherent to some of these approaches include narrow field of regard, low speed operation, and low optical efficiency. An attractive method that we explore is based on optical phased arrays, which has the potential to overcome the aforementioned issues associated with other mechanical and nonmechanical beam steering techniques. The optical array phase locks a number of coherent optical emitters in addition to applying arbitrary phase profiles across the array, thereby synthesizing beam shapes that can be steered and utilized for a diverse range of applications.

  17. Number of phase levels of a talbot array illuminator.

    PubMed

    Zhou, C; Wang, H; Zhao, S; Xi, P; Liu, L

    2001-02-10

    The number of phase levels of a Talbot array illuminator is an important factor in the estimation of practical fabrication complexity and cost. We show that the number (L) of phase levels of a Talbot array illuminator has a simple relationship to the prime number. When there is an alternative pi-phase modulation in the output array, the relations are similar. PMID:18357036

  18. Development of a twin crystal membrane coupled conformable phased array for the inspection of austenitic welds

    SciTech Connect

    Russell, J.; Long, R.; Cawley, P.

    2011-06-23

    The inspection of welded austenitic stainless steel components can be challenging. Austenitic welds contain an anisotropic, inhomogeneous grain structure which causes attenuation, scattering and beam bending. The inspection of components where the weld cap has not been removed is even more difficult due to the irregularity of the surface geometry. A twin crystal membrane coupled device has now been produced containing two linear phased arrays positioned adjacent to one another within the same housing. The arrays are angled relative to one another so that the transducer provides a pseudo-focusing effect at a depth corresponding to the beam crossing point. This type of design is used to improve the signal to noise ratio of the defect response in comparison to simple linear phased array transducer designs and to remove an internal noise signal found in linear phased array devices. Experimental results obtained from the through weld inspection of an austenitic stainless steel component with an undressed weld cap using the twin crystal membrane device are presented. These results demonstrate that small lack of side wall fusion defects can be reliably detected in large complex structures.

  19. A phased antenna array for surface plasmons.

    PubMed

    Dikken, Dirk Jan W; Korterik, Jeroen P; Segerink, Frans B; Herek, Jennifer L; Prangsma, Jord C

    2016-01-01

    Surface plasmon polaritons are electromagnetic waves that propagate tightly bound to metal surfaces. The concentration of the electromagnetic field at the surface as well as the short wavelength of surface plasmons enable sensitive detection methods and miniaturization of optics. We present an optical frequency plasmonic analog to the phased antenna array as it is well known in radar technology and radio astronomy. Individual holes in a thick gold film act as dipolar emitters of surface plasmon polaritons whose phase is controlled individually using a digital spatial light modulator. We show experimentally, using a phase sensitive near-field microscope, that this optical system allows accurate directional emission of surface waves. This compact and flexible method allows for dynamically shaping the propagation of plasmons and holds promise for nanophotonic applications employing propagating surface plasmons. PMID:27121099

  20. A phased antenna array for surface plasmons

    NASA Astrophysics Data System (ADS)

    Dikken, Dirk Jan W.; Korterik, Jeroen P.; Segerink, Frans B.; Herek, Jennifer L.; Prangsma, Jord C.

    2016-04-01

    Surface plasmon polaritons are electromagnetic waves that propagate tightly bound to metal surfaces. The concentration of the electromagnetic field at the surface as well as the short wavelength of surface plasmons enable sensitive detection methods and miniaturization of optics. We present an optical frequency plasmonic analog to the phased antenna array as it is well known in radar technology and radio astronomy. Individual holes in a thick gold film act as dipolar emitters of surface plasmon polaritons whose phase is controlled individually using a digital spatial light modulator. We show experimentally, using a phase sensitive near-field microscope, that this optical system allows accurate directional emission of surface waves. This compact and flexible method allows for dynamically shaping the propagation of plasmons and holds promise for nanophotonic applications employing propagating surface plasmons.

  1. Phase discriminating capacitive array sensor system

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor); Rahim, Wadi (Inventor)

    1993-01-01

    A phase discriminating capacitive sensor array system which provides multiple sensor elements which are maintained at a phase and amplitude based on a frequency reference provided by a single frequency stabilized oscillator. Sensor signals provided by the multiple sensor elements are controlled by multiple phase control units, which correspond to the multiple sensor elements, to adjust the sensor signals from the multiple sensor elements based on the frequency reference. The adjustment made to the sensor signals is indicated by output signals which indicate the proximity of the object. The output signals may also indicate the closing speed of the object based on the rate of change of the adjustment made, and the edges of the object based on a sudden decrease in the adjustment made.

  2. A phased antenna array for surface plasmons

    PubMed Central

    Dikken, Dirk Jan W.; Korterik, Jeroen P.; Segerink, Frans B.; Herek, Jennifer L.; Prangsma, Jord C.

    2016-01-01

    Surface plasmon polaritons are electromagnetic waves that propagate tightly bound to metal surfaces. The concentration of the electromagnetic field at the surface as well as the short wavelength of surface plasmons enable sensitive detection methods and miniaturization of optics. We present an optical frequency plasmonic analog to the phased antenna array as it is well known in radar technology and radio astronomy. Individual holes in a thick gold film act as dipolar emitters of surface plasmon polaritons whose phase is controlled individually using a digital spatial light modulator. We show experimentally, using a phase sensitive near-field microscope, that this optical system allows accurate directional emission of surface waves. This compact and flexible method allows for dynamically shaping the propagation of plasmons and holds promise for nanophotonic applications employing propagating surface plasmons. PMID:27121099

  3. A Hemispherical Sparse Phased Array Design For Low Frequency Transcranial Focused Ultrasound Applications Without Skull-Specific Phase Aberration Correction

    NASA Astrophysics Data System (ADS)

    Yin, Xiangtao; Hynynen, Kullervo

    2006-05-01

    A sparse large-element hemispherical phased array scheme was investigated for low frequency transcranial focused ultrasound applications without skull-specific phase aberration correction. The simulated transcranial focused beams in brain from the randomly distributed sparse array elements (0.25 MHz, 125 mm radius of curvature, 250 mm diameter, 50% sparsity of 953 square elements of 10 mm spacing) could be steered without skull specific aberration correction at 0.25 MHz. The 28 foci were on average 1.7±1.2 mm shifted from their intended locations. The average -3 dB beam width and length were 3.3±1.2 mm and 6.3±2.2 mm, respectively. The sidelobe levels ranged from 28% to 62% of the peak pressure values. The focal beam was steerable 35 mm laterally away from the transducer center axis and 30 mm axially in the transducer center axis when the sidelobe pressure values were 50% of or less than the peak pressure values. This allows the array to be mechanically aimed to one quarter of the brain and then electronically steered. The sparse array design offers a tradeoff between the best beam steering range and the manageable number of elements for a practical clinical system.

  4. Phased-array ultrasonic surface contour mapping system. Technical note

    SciTech Connect

    Fasching, G.E.; Loudin, W.J.; Paton, D.E.; Smith, N.S. Jr.

    1992-11-01

    The development of reliable mechanistic models for prediction of conventional and fluidized-bed combustor and gasifier operation and solids flow behavior in silos or other solids handling and storage components requires knowledge of the contained solids flow characteristics. This knowledge is gained from dynamic experimental measurements of bed top surface contours in addition to measurements of bulk bed properties. The surface contour mapping system (SCMS) provides a means of generating surface contour maps in real time with a unique, automatically focused, density-compensated, digital phased-array scanning, ultrasonic-range measurement system. The system is designed to operate in environments having gas temperatures up to 1,600 {degree}F and pressures to 1,000 psig. Computer simulation of several SCMS candidates and acoustic carrier modulation techniques indicates that a surface measurement resolution of {plus_minus}2 inches over a range of 5 to 20 feet distance between the transmit/receive (T/R) transducers and the bed surface can be expected. The simulation of a particular design, a 9-T/R, 25-pixel bed surface, in which the level of each pixel was randomly set between 5 and 7 feet below the plane of the T/R transducers, then measured using two different modulation techniques, produced excellent results. The simulation of this surface contour mapping system determined the value of the level of each of the 25 pixels to within {plus_minus}1 inch for over 95 percent of more than 100 test cases for one of the modulation techniques, and for over 99 percent of about 100 test cases for a second modulation technique. A hardware implementation of the design simulated but using only a two-T/R, three-pixel SCMS produced results very closely approximating those obtained during the simulation.

  5. Phased Antenna Array for Global Navigation Satellite System Signals

    NASA Technical Reports Server (NTRS)

    Turbiner, Dmitry (Inventor)

    2015-01-01

    Systems and methods for phased array antennas are described. Supports for phased array antennas can be constructed by 3D printing. The array elements and combiner network can be constructed by conducting wire. Different parameters of the antenna, like the gain and directivity, can be controlled by selection of the appropriate design, and by electrical steering. Phased array antennas may be used for radio occultation measurements.

  6. Noninvasive Ultrasonic Glucose Sensing with Large Pigs (∼200 Pounds) Using a Lightweight Cymbal Transducer Array and Biosensors

    PubMed Central

    Park, Eun-Joo; Werner, Jacob; Beebe, Joshua; Chan, Samantha; Barrie Smith, Nadine

    2009-01-01

    Background To prevent complications in diabetes, the proper management of blood glucose levels is essential. Since conventional glucose meters require pricking fingers or other areas of the skin, a noninvasive method for monitoring blood glucose levels is desired. Using a lightweight cymbal transducer array, this study was conducted to noninvasively determine the glucose levels of pigs having a similar size to humans. Method In vivo experiments using eight pigs (∼200 pounds) were performed in five groups. A cymbal array with four biosensors was attached to the axillary area of the pig. The array was operated at 20 kHz at special peak–temporal peak intensity (Isptp) equal to 50 or 100 mW/cm2 for 5, 10, or 20 minutes. After the ultrasound exposure, glucose concentrations of the interstitial fluid were determined using biosensors. For comparison, glucose levels of blood samples collected from the ear vein were measured by a commercial glucose meter. Result In comparison, glucose levels determined by a cymbal array and biosensor system were close to those measured by a glucose meter. After a 20-minute ultrasound exposure at Isptp = 100 mW/cm2, the average glucose level determined by the ultrasound system was 175 ± 7 mg/dl, which is close to 166 ± 5 mg/dl measured by the glucose meter. Conclusion Results indicate the feasibility of using a cymbal array for noninvasive glucose sensing on pigs having a similar size to humans. Further studies on the ultrasound conditions, such as frequency, intensity, and exposure time, will be continued for effective glucose sensing. PMID:20144290

  7. Microfabrication of electrode patterns for high-frequency ultrasound transducer arrays.

    PubMed

    Bernassau, Anne L; García-Gancedo, Luis; Hutson, David; Démoré, Christine E M; McAneny, Jim J; Button, Tim W; Cochran, Sandy

    2012-08-01

    High-frequency ultrasound is needed for medical imaging with high spatial resolution. A key issue in the development of ultrasound imaging arrays to operate at high frequencies (≥30 MHz) is the need for photolithographic patterning of array electrodes. To achieve this directly on 1-3 piezocomposite, the material requires not only planar, parallel, and smooth surfaces, but also an epoxy composite filler that is resistant to chemicals, heat, and vacuum. This paper reports, first, on the surface finishing of 1-3 piezocomposite materials by lapping and polishing. Excellent surface flatness has been obtained, with an average surface roughness of materials as low as 3 nm and step heights between ceramic/polymer of ∼80 nm. Subsequently, high-frequency array elements were patterned directly on top of these surfaces using a photolithography process. A 30-MHz linear array electrode pattern with 50-μm element pitch has been patterned on the lapped and polished surface of a high-frequency 1-3 piezocomposite. Excellent electrode edge definition and electrical contact to the composite were obtained. The composite has been lapped to a final thickness of ∼55 μm. Good adhesion of electrodes on the piezocomposite has been achieved and electrical impedance measurements have demonstrated their basic functionality. The array was then packaged, and acoustic pulse-echo measurements were performed. These results demonstrate that direct patterning of electrodes by photolithography on 1-3 piezocomposite is feasible for fabrication of high-frequency ultrasound arrays. Furthermore, this method is more conducive to mass production than other reported array fabrication techniques. PMID:22899129

  8. Large Volume Coagulation Utilizing Multiple Cavitation Clouds Generated by Array Transducer Driven by 32 Channel Drive Circuits

    NASA Astrophysics Data System (ADS)

    Nakamura, Kotaro; Asai, Ayumu; Sasaki, Hiroshi; Yoshizawa, Shin; Umemura, Shin-ichiro

    2013-07-01

    High-intensity focused ultrasound (HIFU) treatment is a noninvasive treatment, in which focused ultrasound is generated outside the body and coagulates a diseased tissue. The advantage of this method is minimal physical and mental stress to the patient, and the disadvantage is the long treatment time caused by the smallness of the therapeutic volume by a single exposure. To improve the efficiency and shorten the treatment time, we are focusing attention on utilizing cavitation bubbles. The generated microbubbles can convert the acoustic energy into heat with a high efficiency. In this study, using the class D amplifiers, which we have developed, to drive the array transducer, we demonstrate a new method to coagulate a large volume by a single HIFU exposure through generating cavitation bubbles distributing in a large volume and vibrating all of them. As a result, the coagulated volume by the proposed method was 1.71 times as large as that of the conventional method.

  9. Stability of Programmable Shunt Valve Settings with Simultaneous Use of the Optune Transducer Array: A Case Report

    PubMed Central

    Chan, Andrew K; Winkler, Ethan A; Viner, Jennifer A; Taylor, Jennie W; McDermott, Michael W.

    2016-01-01

    The Optune® transducer array (Novocure Ltd., Haifa, Israel) is an FDA-approved noninvasive regional therapy that aims to inhibit the growth of glioblastoma multiforme (GBM) cells via utilization of alternating electric fields. Some patients with GBM may develop hydrocephalus and benefit from subsequent shunt placement, but special attention must be paid to patients in whom programmable valves are utilized, given the potential effect of the magnetic fields on valve settings. We present the first case report illustrating the stability of programmable shunt valve settings in a neurosurgical patient undergoing therapy with the Optune device. In this study, shunt valve settings were stable over a period of five days despite Optune therapy. This is reassuring for patients with GBM who require simultaneous treatment with both the Optune device and a programmable shunt system. PMID:27551653

  10. Stability of Programmable Shunt Valve Settings with Simultaneous Use of the Optune Transducer Array: A Case Report.

    PubMed

    Chan, Andrew K; Birk, Harjus S; Winkler, Ethan A; Viner, Jennifer A; Taylor, Jennie W; McDermott, Michael W

    2016-01-01

    The Optune® transducer array (Novocure Ltd., Haifa, Israel) is an FDA-approved noninvasive regional therapy that aims to inhibit the growth of glioblastoma multiforme (GBM) cells via utilization of alternating electric fields. Some patients with GBM may develop hydrocephalus and benefit from subsequent shunt placement, but special attention must be paid to patients in whom programmable valves are utilized, given the potential effect of the magnetic fields on valve settings. We present the first case report illustrating the stability of programmable shunt valve settings in a neurosurgical patient undergoing therapy with the Optune device. In this study, shunt valve settings were stable over a period of five days despite Optune therapy. This is reassuring for patients with GBM who require simultaneous treatment with both the Optune device and a programmable shunt system. PMID:27551653

  11. Production and Validation of Acoustic Field to Enhance Trapping Efficiency of Microbubbles by Using a Matrix Array Transducer

    NASA Astrophysics Data System (ADS)

    Hosaka, Naoto; Koda, Ren; Onogi, Shinya; Mochizuki, Takashi; Masuda, Kohji

    2013-07-01

    We have developed a new matrix array transducer for controlling the behavior of microbubbles, which is different from that for high-intensity focused ultrasound (HIFU) therapy, in order to emit continuous wave by designing an acoustic field including multiple focal points. In the experiment using a thin-channel model, a wider acoustic field has an advantage for trapping microbubbles. In the experiment using a straight-path model, we have confirmed that a higher concentration of acoustic energy does not result in more aggregates. The dispersion of acoustic energy is important because the trapping performance is affected by the relationship between the shape of the acoustic field and the concentration of the suspension.

  12. Through Weld Inspection of Wrought Stainless Steel Piping Using Phased-Array Ultrasonic Probes.

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2004-08-05

    A study was conducted to assess the ability of phased-array ultrasonic techniques to detect and accurately determine the size of flaws from the far-side of wrought austenitic piping welds. Far-side inspections of these welds are currently performed on a “best effort” basis and do not conform to ASME Code Section XI Appendix VIII performance demonstration requirements. For this study, four circumferential welds in 610mm diameter, 36mm thick ASTM A-358, Grade 304 vintage austenitic stainless steel pipe were examined. The welds were fabricated with varied welding parameters; both horizontal and vertical pipe orientations were used, with air and water backing, to simulate field welding conditions. A series of saw cuts, electro-discharge machined (EDM) notches, and implanted fatigue cracks were placed into the heat affected zones of the welds. The saw cuts and notches range in depth from 7.5% to 28.4% through-wall. The implanted cracks ranged in depth from 5% through wall to 64% through wall. The welds were examined with two phased-array probes, a 2.0 MHz transmit-receive longitudinal wave array and a 2.0 MHz transmit-receive shear wave array. These examinations showed that both phased-array transducers were able to detect and accurately length-size, but not depth size, all of the notches and flaws through the welds. The phased-array results were not strongly affected by the different welding techniques used in each weld.

  13. Coherence-Weighted Synthetic Focusing Applied to Photoacoustic Imaging Using a High-Frequency Annular-Array Transducer

    PubMed Central

    Chitnis, Parag V.; Aristizábal, Orlando; Filoux, Erwan; Sampathkumar, Ashwin; Mamou, Jonathan; Ketterling, Jeffrey A.

    2016-01-01

    This paper presents an adaptive synthetic-focusing scheme that, when applied to photoacoustic (PA) data acquired using an annular array, improves focusing across a greater imaging depth and enhances spatial resolution. The imaging system was based on a 40-MHz, 5-element, annular-array transducer with a focal length of 12 mm and an 800-μm diameter hole through its central element to facilitate coaxial delivery of 532-nm laser. The transducer was raster-scanned to facilitate 3D acquisition of co-registered ultrasound and PA image data. Three synthetic-focusing schemes were compared for obtaining PA A-lines for each scan location: delay-and-sum (DAS), DAS weighted with a coherence factor (DAS + CF), and DAS weighted with a sign-coherence factor (DAS + SCF). Bench-top experiments that used an 80-μm hair were performed to assess the enhancement provided by the two coherence-based schemes. Both coherence-based schemes increased the signal-to-noise ratio by approximately 10 dB. When processed using the DAS-only scheme, the lateral dimension of the hair in a PA image with 20 dB dynamic range was between 300 μm and 1 mm for imaging depth ranging from 8 to 20 mm. In comparison, the DAS + CF scheme resulted in a lateral dimension of 200 to 450 μm over the same range. The DAS + SCF synthetic focusing further improved the smallest-resolvable dimension, which was between 150 and 400 μm over the same range of imaging depth. When used on PA data obtained from a 12-day-old mouse embryo, the DAS + SCF processing improved visualization of neurovasculature. PMID:25925675

  14. Coherence-Weighted Synthetic Focusing Applied to Photoacoustic Imaging Using a High-Frequency Annular-Array Transducer.

    PubMed

    Chitnis, Parag V; Aristizábal, Orlando; Filoux, Erwan; Sampathkumar, Ashwin; Mamou, Jonathan; Ketterling, Jeffrey A

    2016-01-01

    This paper presents an adaptive synthetic-focusing scheme that, when applied to photoacoustic (PA) data acquired using an annular array, improves focusing across a greater imaging depth and enhances spatial resolution. The imaging system was based on a 40-MHz, 5-element, annular-array transducer with a focal length of 12 mm and an 800-µm diameter hole through its central element to facilitate coaxial delivery of 532-nm laser. The transducer was raster-scanned to facilitate 3D acquisition of co-registered ultrasound and PA image data. Three synthetic-focusing schemes were compared for obtaining PA A-lines for each scan location: delay-and-sum (DAS), DAS weighted with a coherence factor (DAS + CF), and DAS weighted with a sign-coherence factor (DAS + SCF). Bench-top experiments that used an 80-µm hair were performed to assess the enhancement provided by the two coherence-based schemes. Both coherence-based schemes increased the signal-to-noise ratio by approximately 10 dB. When processed using the DAS-only scheme, the lateral dimension of the hair in a PA image with 20 dB dynamic range was between 300 µm and 1 mm for imaging depth ranging from 8 to 20 mm. In comparison, the DAS + CF scheme resulted in a lateral dimension of 200 to 450 µm over the same range. The DAS + SCF synthetic focusing further improved the smallest-resolvable dimension, which was between 150 and 400 µm over the same range of imaging depth. When used on PA data obtained from a 12-day-old mouse embryo, the DAS + SCF processing improved visualization of neurovasculature. PMID:25925675

  15. Ghost artifact cancellation using phased array processing.

    PubMed

    Kellman, P; McVeigh, E R

    2001-08-01

    In this article, a method for phased array combining is formulated which may be used to cancel ghosts caused by a variety of distortion mechanisms, including space variant distortions such as local flow or off-resonance. This method is based on a constrained optimization, which optimizes SNR subject to the constraint of nulling ghost artifacts at known locations. The resultant technique is similar to the method known as sensitivity encoding (SENSE) used for accelerated imaging; however, in this formulation it is applied to full field-of-view (FOV) images. The method is applied to multishot EPI with noninterleaved phase encode acquisition. A number of benefits, as compared to the conventional interleaved approach, are reduced distortion due to off-resonance, in-plane flow, and EPI delay misalignment, as well as eliminating the need for echo-shifting. Experimental results demonstrate the cancellation for both phantom as well as cardiac imaging examples. PMID:11477638

  16. Time Reversal Beam Focusing of Ultrasonic Array Transducer on a Defect in a Two Layer Medium

    NASA Astrophysics Data System (ADS)

    Jeong, Hyunjo; Lee, Jeong-Sik; Lee, Chung-Hoon

    2010-02-01

    The ability of time reversal techniques to focus ultrasonic beams on the source location is important in many aspects of ultrasonic nondestructive evaluation. In this paper, we investigate the time reversal beam focusing of ultrasonic array sensors on a defect in layered media. Numerical modeling is performed using the commercially available software which employs a time domain finite difference method. Two different time reversal approaches are considered—the through transmission and the pulse-echo. Linear array sensors composed of N elements of line sources are used for signal reception/excitation, time reversal, and reemission in time reversal processes associated with the scattering source of a side-drilled hole located in the second layer of two layer structure. The simulation results demonstrate the time reversal focusing even with multiple reflections from the interface of layered structure. We examine the focusing resolution that is related to the propagation distance, the size of array sensor and the wavelength.

  17. Phased-array design for MST and ST radars

    NASA Technical Reports Server (NTRS)

    Ecklund, W. L.

    1986-01-01

    All of the existing radar systems fully dedicated to clear-air radar studies use some type of phased-array antennas. The effects of beam-steering techniques including feed networks and phase shifters; sidelobe control; ground-clutter suppression; low altitude coverage; arrays with integrated radiating elements and feed networks; analysis of coaxial-collinear antennas; use of arrays with multiple beams; and array testing and measure on structural design of the antenna are discussed.

  18. In Vivo Evaluations of a Phased Ultrasound Array for Transesophageal Cardiac Ablation

    NASA Astrophysics Data System (ADS)

    Jaiswal, Devina; Werner, Jacob; Park, Eun-Joo; Francischelli, David; Smith, Nadine Barrie

    2010-03-01

    Atrial fibrillation is one of the most common arrhythmias that affects over 2.2 million Americans each year. Catheter ablation, one of the effective treatments, has shown high rate of success in treating paroxysmal atrial fibrillation. Currently, radiofrequency which is being used for catheter ablation is an invasive procedure. Measurable morbidity and significant costs and time are associated with this modality of treatment of permanent or persistent atrial fibrillation. In order to address these issues, a transesophageal ultrasound applicator for noninvasive cardiac ablation was designed, developed and evaluated. The ultrasound energy delivered by the phased array was used to create a lesion in the myocardial tissue. Various factors, simulation results of transducer arrays, current transesophageal medical devices, and throat anatomy, were considered while designing a phased ultrasound transducer that can be inserted into the esophagus. For this research, a two-dimensional sparse phased array with flat tapered elements was fabricated and evaluated in in vivo experiments. Five pigs were anesthetized; the array was passed transesophagealy and positioned over the heart. An operating frequency of 1.6 MHz and 8˜15 minutes of array operation resulted in both single and multiple lesions on atrial and ventricular myocardium. The average size of lesions was 5.1±2.1 mm in diameter and 7.8±2.5 mm in length. Experimental results indicate that the array delivered sufficient power to produce ablation at the focal point while not grossly damaging the tissue surrounding the area of interest. These results demonstrate a potential application of the ultrasound applicator for noninvasive transesophageal cardiac surgery in atrial fibrillation treatment.

  19. Photoacoustic imaging for deep targets in the breast using a multichannel 2D array transducer

    NASA Astrophysics Data System (ADS)

    Xie, Zhixing; Wang, Xueding; Morris, Richard F.; Padilla, Frederic R.; Lecarpentier, Gerald L.; Carson, Paul L.

    2011-03-01

    A photoacoustic (PA) imaging system was developed to achieve high sensitivity for the detection and characterization of vascular anomalies in the breast in the mammographic geometry. Signal detection from deep in the breast was achieved by a broadband 2D PVDF planar array that has a round shape with one side trimmed straight to improve fit near the chest wall. This array has 572 active elements and a -6dB bandwidth of 0.6-1.7 MHz. The low frequency enhances imaging depth and increases the size of vascular collections displayed without edge enhancement. The PA signals from all the elements go through low noise preamplifiers in the probe that are very close to the array elements for optimized noise control. Driven by 20 independent on-probe signal processing channels, imaging with both high sensitivity and good speed was achieved. To evaluate the imaging depth and the spatial resolution of this system,2.38mm I.D. artificial vessels embedded deeply in ex vivo breasts harvested from fresh cadavers and a 3mm I.D. tube in breast mimicking phantoms made of pork loin and fat tissues were imaged. Using near-infrared laser light with incident energy density within the ANSI safety limit, imaging depths of up to 49 mm in human breasts and 52 mm in phantoms were achieved. With a high power tunable laser working on multiple wavelengths, this system might contribute to 3D noninvasive imaging of morphological and physiological tissue features throughout the breast.

  20. S-band antenna phased array communications system

    NASA Technical Reports Server (NTRS)

    Delzer, D. R.; Chapman, J. E.; Griffin, R. A.

    1975-01-01

    The development of an S-band antenna phased array for spacecraft to spacecraft communication is discussed. The system requirements, antenna array subsystem design, and hardware implementation are examined. It is stated that the phased array approach offers the greatest simplicity and lowest cost. The objectives of the development contract are defined as: (1) design of a medium gain active phased array S-band communications antenna, (2) development and test of a model of a seven element planar array of radiating elements mounted in the appropriate cavity matrix, and (3) development and test of a breadboard transmit/receive microelectronics module.

  1. Modeling and optimization of non-phased two-dimensional ultrasonic arrays

    NASA Astrophysics Data System (ADS)

    Denisov, Alexey A.

    Ultrasonic image acquisition with non-phased 2D arrays is a relatively new method in NDE inspection. Historically, ultrasonic array development progressed mostly in the medical imaging where phased arrays found a great application. However, in the field of NDE inspection of metals, heavy plastics and composites, and many other materials the applicability of phased arrays is often restricted due to physical limitations. On the other hand, using versatile systems with mechanical scanning is not always convenient. Therefore, non-phased arrays of independent elements have a strong potential for becoming a valuable tool for rapid ultrasonic image acquisition in the industrial environment as well as in many other areas where conventional methods may not be applicable. The main motivation of this work is to build the necessary mathematical apparatus for estimating the process of signal and image formation in such systems. A model of signal penetration through a complex multilayered structure with non-parallel interfaces is discussed in the plane-wave approximation. This model is then refined to finite-size transducers and finite-size defects inside the sample. A new method of obtaining the beam structure in such multi-layered media is presented. The advantage of this method is that it allows for a very fast calculation while the precision is still comparable to more precise and more computationally expensive methods. A new method of calculating the response of the transducer to defects inside the sample is presented and discussed. The results of numerical calculations using these two methods are discussed and compared with experimental data. Using these models, image formation algorithms together with new image refining techniques are discussed.

  2. Multiband Photonic Phased-Array Antenna

    NASA Technical Reports Server (NTRS)

    Tang, Suning

    2015-01-01

    A multiband phased-array antenna (PAA) can reduce the number of antennas on shipboard platforms while offering significantly improved performance. Crystal Research, Inc., has developed a multiband photonic antenna that is based on a high-speed, optical, true-time-delay beamformer. It is capable of simultaneously steering multiple independent radio frequency (RF) beams in less than 1,000 nanoseconds. This high steering speed is 3 orders of magnitude faster than any existing optical beamformer. Unlike other approaches, this technology uses a single controlling device per operation band, eliminating the need for massive optical switches, laser diodes, and fiber Bragg gratings. More importantly, only one beamformer is needed for all antenna elements.

  3. Joint stars phased array radar antenna

    NASA Astrophysics Data System (ADS)

    Shnitkin, Harold

    1994-10-01

    The Joint STARS phased array radar system is capable of performing long range airborne surveillance and was used during the Persian Gulf war on two E8-A aircraft to fly many around-the-clock missions to monitor the Kuwait and Iraq battlefield from a safe distance behind the front lines. This paper is a follow-on to previous publications on the subject of the Joint STARS antenna and deals mainly with mission performance and technical aspects not previously covered. Radar data of troop movements and armament installations will be presented, a brief review of the antenna design is given, followed by technical discussions concerning the three-port interferometry, gain and sidelobe design approach, cost control, range test implementation and future improvements.

  4. Wavelet Analysis for Acoustic Phased Array

    NASA Astrophysics Data System (ADS)

    Kozlov, Inna; Zlotnick, Zvi

    2003-03-01

    Wavelet spectrum analysis is known to be one of the most powerful tools for exploring quasistationary signals. In this paper we use wavelet technique to develop a new Direction Finding (DF) Algorithm for the Acoustic Phased Array (APA) systems. Utilising multi-scale analysis of libraries of wavelets allows us to work with frequency bands instead of individual frequency of an acoustic source. These frequency bands could be regarded as features extracted from quasistationary signals emitted by a noisy object. For detection, tracing and identification of a sound source in a noisy environment we develop smart algorithm. The essential part of this algorithm is a special interacting procedure of the above-mentioned DF-algorithm and the wavelet-based Identification (ID) algorithm developed in [4]. Significant improvement of the basic properties of a receiving APA pattern is achieved.

  5. A Phased Array Approach to Rock Blasting

    SciTech Connect

    Leslie Gertsch; Jason Baird

    2006-07-01

    A series of laboratory-scale simultaneous two-hole shots was performed in a rock simulant (mortar) to record the shock wave interference patterns produced in the material. The purpose of the project as a whole was to evaluate the usefulness of phased array techniques of blast design, using new high-precision delay technology. Despite high-speed photography, however, we were unable to detect the passage of the shock waves through the samples to determine how well they matched the expected interaction geometry. The follow-up mine-scale tests were therefore not conducted. Nevertheless, pattern analysis of the vectors that would be formed by positive interference of the shockwaves from multiple charges in an ideal continuous, homogeneous, isotropic medium indicate the potential for powerful control of blast design, given precise characterization of the target rock mass.

  6. Feasibility of Using Lateral Mode Coupling Method for a Large Scale Ultrasound Phased Array for Noninvasive Transcranial Therapy

    PubMed Central

    Song, Junho; Hynynen, Kullervo

    2009-01-01

    A hemispherical-focused, ultrasound phased array was designed and fabricated using 1372 cylindrical piezoelectric transducers that utilize lateral coupling for noninvasive transcranial therapy. The cylindrical transducers allowed the electrical impedance to be reduced by at least an order of magnitude, such that effective operation could be achieved without electronic matching circuits. In addition, the transducer elements generated the maximum acoustic average surface intensity of 27 W/cm2. The array, driven at the low (306 kHz) or high frequency (840 kHz), achieved excellent focusing through an ex vivo human skull and an adequate beam steering range for clinical brain treatments. It could electronically steer the ultrasound beam over cylindrical volumes of 100 mm in diameter and 60 mm in height at 306 kHz, and 30-mm in diameter and 30-mm in height at 840 kHz. A scanning laser vibrometer was used to investigate the radial and length mode vibrations of the element. The maximum pressure amplitudes through the skull at the geometric focus were predicted to be 5.5 MPa at 306 kHz and 3.7 MPa at 840 kHz for RF power of 1 W on each element. This is the first study demonstrating the feasibility of using cylindrical transducer elements and lateral coupling in construction of ultrasound phased arrays. PMID:19695987

  7. Three-dimensional Ultrasound Molecular Imaging of Angiogenesis in Colon Cancer using a Clinical Matrix Array Ultrasound Transducer

    PubMed Central

    Wang, Huaijun; Kaneko, Osamu F.; Tian, Lu; Hristov, Dimitre; Willmann, Jürgen K.

    2015-01-01

    Objectives We sought to assess the feasibility and reproducibility of three-dimensional (3D) ultrasound molecular imaging (USMI) of vascular endothelial growth factor receptor 2 (VEGFR2) expression in tumor angiogenesis using a clinical matrix array transducer and a clinical grade VEGFR2-targeted contrast agent in a murine model of human colon cancer. Materials and Methods Animal studies were approved by the Institutional Administrative Panel on Laboratory Animal Care. Mice with human colon cancer xenografts (n=33) were imaged with a clinical ultrasound system and transducer (Philips iU22; X6-1) following intravenous injection of either clinical grade VEGFR2-targeted microbubbles (MBVEGFR2) or non-targeted control microbubbles (MBControl). Nineteen mice were scanned twice to assess imaging reproducibility. Fourteen mice were scanned both before and 24h after treatment with either bevacizumab (n=7) or saline only (n=7). 3D USMI datasets were retrospectively reconstructed into multiple consecutive 1-mm thick USMI data sets to simulate 2D imaging. Vascular VEGFR2 expression was assessed ex vivo using immunofluorescence. Results 3D USMI was highly reproducible using both MBVEGFR2 and MBControl (ICC=0.83). VEGFR2-targeted USMI signal significantly (P=0.02) decreased by 57% following anti-angiogenic treatment compared to the control group, which correlated well with ex vivo VEGFR2 expression on immunofluorescence (rho=0.93, P=0.003). If only central 1-mm tumor planes were analyzed to assess anti-angiogenic treatment response, the USMI signal change was significantly (P=0.006) overestimated by an average of 27% (range, 2–73%) compared to 3D USMI. Conclusions 3D USMI is feasible and highly reproducible and allows accurate assessment and monitoring of VEGFR2 expression in tumor angiogenesis in a murine model of human colon cancer. PMID:25575176

  8. Receiver Would Control Phasing of a Phased-Array Antenna

    NASA Technical Reports Server (NTRS)

    Dunn, Charles E.; Young, Lawrence E.

    2006-01-01

    In a proposed digital signal-processing technique, a radio receiver would control the phasing of a phased-array antenna to aim the peaks of the antenna radiation pattern toward desired signal sources while aiming the nulls of the pattern toward interfering signal sources. The technique was conceived for use in a Global Positioning System (GPS) receiver, for which the desired signal sources would be GPS satellites and typical interference sources would be terrestrial objects that cause multipath propagation. The technique could also be used to optimize reception in spread-spectrum cellular-telephone and military communication systems. During reception of radio signals in a conventional phased-array antenna system, received signals at their original carrier frequencies are phase-shifted, then combined by analog circuitry. The combination signal is then subjected to down-conversion and demodulation. In a system according to the proposed technique (see figure), the signal received by each antenna would be subjected to down-conversion, spread-spectrum demodulation, and correlation; this processing would be performed separately from, and simultaneously with, similar processing of signals received by the other antenna elements. Following analog down-conversion to baseband, the signals would be digitized, and all subsequent processing would be digital. In the digital process, residual carriers would be removed and each signal would be correlated with a locally generated model pseudorandum-noise code, all following normal GPS procedure. As part of this procedure, accumulated values would be added in software and the resulting signals would be phase-shifted in software by the amounts necessary to synthesize the desired antenna directional gain pattern of peaks and nulls. The principal advantage of this technique over the conventional radio-frequency-combining technique is that the parallel digital baseband processing of the signals from the various antenna elements would be

  9. An ultrasound cylindrical phased array for deep heating in the breast: theoretical design using heterogeneous models

    NASA Astrophysics Data System (ADS)

    Bakker, J. F.; Paulides, M. M.; Obdeijn, I. M.; van Rhoon, G. C.; van Dongen, K. W. A.

    2009-05-01

    The objective of this theoretical study is to design an ultrasound (US) cylindrical phased array that can be used for hyperthermia (40-44 °C) treatment of tumours in the intact breast. Simultaneously, we characterize the influence of acoustic and thermal heterogeneities on the specific absorption rate (SAR) and temperature patterns to determine the necessity of using heterogeneous models for a US applicator design and treatment planning. Cylindrical configurations of monopole transducers are studied on their ability to generate interference patterns that can be steered electronically to the location of the target region. Hereto, design parameters such as frequency, number of transducers per ring, ring distance and number of rings are optimized to obtain a small primary focus, while suppressing secondary foci. The models account for local heterogeneities in both acoustic (wave velocity and absorption) and thermal (blood perfusion rate, heat capacity and conductivity) tissue properties. We used breast models with a central tumour (30 × 20 × 38 mm3) and an artificial thorax tumour (sphere with a radius of 25 mm) to test the design. Simulations predict that a US cylindrical phased array, consisting of six rings with 32 transducers per ring, a radius of 75 mm and 66 mm distance between the first and sixth transducer ring, operating at a frequency of 100 kHz, can be used to obtain 44 °C in the centre of tumours located anywhere in the intact breast. The dimensions of the volumes enclosed by the 41 °C iso-temperature are 19 × 19 × 21 mm3 and 21 × 21 × 32 mm3 for the central and the thorax tumours, respectively. It is demonstrated that acoustic and thermal heterogeneities do not disturb the SAR and temperature patterns.

  10. Phased-array ultrasound technology enhances accuracy of dual frequency ultrasound measurements - towards improved ultrasound bone diagnostics.

    PubMed

    Linder, Hans; Malo, Markus K H; Liukkonen, Jukka; Jurvelin, Jukka S; Töyräs, Juha

    2016-08-01

    Overlying soft tissues attenuate ultrasound backscattered from bone, complicating diagnostics of osteoporosis at the most important fracture sites. Dual-frequency ultrasound technique (DFUS) has been proposed to solve this problem through determination of thickness and composition of overlying soft tissue. This study applies DFUS technique for the first time with a phased-array transducer to investigate if the thickness of two interfering layers (oil and water) can be accurately determined in a variety of configurations. Results indicate that DFUS may be used with phased-array ultrasound systems, making them a suitable combination to consider in future development of clinical in vivo ultrasound methodologies. PMID:27187271

  11. Phase-locked injection laser arrays with variable stripe spacing

    NASA Technical Reports Server (NTRS)

    Ackley, Donald E.; Butler, Jerome K.; Ettenberg, Michael

    1986-01-01

    A phase-locked injection laser array is described which utilizes variations in spacing of identical lasing elements to vary the coupling between them. A coupled-mode analysis indicates that excellent matching of fundamental array mode to a uniform gain distribution can be obtained. Observation of the array emission patterns confirms the results of the coupled-mode analysis.

  12. Crosstalk Reduction for High-Frequency Linear-Array Ultrasound Transducers Using 1–3 Piezocomposites With Pseudo-Random Pillars

    PubMed Central

    Yang, Hao-Chung; Cannata, Jonathan; Williams, Jay; Shung, K. Kirk

    2013-01-01

    The goal of this research was to develop a novel diced 1–3 piezocomposite geometry to reduce pulse–echo ring down and acoustic crosstalk between high-frequency ultrasonic array elements. Two PZT-5H-based 1–3 composites (10 and 15 MHz) of different pillar geometries [square (SQ), 45° triangle (TR), and pseudo-random (PR)] were fabricated and then made into single-element ultrasound transducers. The measured pulse–echo waveforms and their envelopes indicate that the PR composites had the shortest −20-dB pulse length and highest sensitivity among the composites evaluated. Using these composites, 15-MHz array subapertures with a 0.95λ pitch were fabricated to assess the acoustic crosstalk between array elements. The combined electrical and acoustical crosstalk between the nearest array elements of the PR array sub-apertures (−31.8 dB at 15 MHz) was 6.5 and 2.2 dB lower than those of the SQ and the TR array subapertures, respectively. These results demonstrate that the 1–3 piezocomposite with the pseudo-random pillars may be a better choice for fabricating enhanced high-frequency linear-array ultrasound transducers; especially when mechanical dicing is used. PMID:23143580

  13. Reconfigurable Wave Velocity Transmission Lines for Phased Arrays

    NASA Technical Reports Server (NTRS)

    Host, Nicholas Keith; Chen, Chi-Chih; Volakis, John L.

    2012-01-01

    This presentation discussed a novel phased array with an emphasis to simplify the array feed. Specifically, we will demonstrate a simple, low cost feeding approach by mechanically controlling the substrate thickness. The array feed lines are constructed from parallel plate transmission lines whose thickness are adjusted to control their effective dielectric constant (Epsilon_eff). As a result the phase delay/excitation at each array element will be adjusted per desired beam direction. The proposed antenna elements will be overlapping dipoles operating over a 2:1 bandwidth in the Ku-Band spectrum. Preliminary simulation and experimental demonstration of such an array will be presented.

  14. Supermode analysis of phase-locked arrays of semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Kapon, E.; Yariv, A.; Katz, J.

    1984-01-01

    The optical characteristics of phase-locked semiconductor laser arrays are formulated in terms of the array supermodes, which are the eigenmodes of the composite-array waveguide, by using coupled-mode theory. These supermodes are employed to calculate the near fields, the far fields, and the difference in the longitudinal-mode oscillation wavelengths of the array. It is shown that the broadening in the far-field beam divergence, as well as the broadening of each of the longitudinal modes that were observed in phase-locked arrays, may arise from the excitation of an increasing number of supermodes at increasing pumping levels.

  15. Microstrip technology and its application to phased array compensation

    NASA Technical Reports Server (NTRS)

    Dudgeon, J. E.; Daniels, W. D.

    1972-01-01

    A systematic analysis of mutual coupling compensation using microstrip techniques is presented. A method for behind-the-array coupling of a phased antenna array is investigated as to its feasibility. The matching scheme is tried on a rectangular array of one half lambda 2 dipoles, but it is not limited to this array element or geometry. In the example cited the values of discrete components necessary were so small an L-C network is needed for realization. Such L-C tanks might limit an otherwise broadband array match, however, this is not significant for this dipole array. Other areas investigated were balun feeding and power limits of spiral antenna elements.

  16. Phase behaviour and phase separation kinetics measurement using acoustic arrays

    NASA Astrophysics Data System (ADS)

    Khammar, M.; Shaw, J. M.

    2011-10-01

    Speed of sound and acoustic wave attenuation are sensitive to fluid phase composition and to the presence of liquid-liquid interfaces. In this work, the use of an acoustic array comprising 64 elements as a non-intrusive sensor for liquid-liquid interface, phase separation kinetics measurement in bulk fluids, and local composition measurement in porous media is illustrated. Three benchmark examples: the phase behaviour of methanol + mixed hexanes and methanol + heptane mixtures at 25.0 °C and 1 bar, and Athabasca bitumen + heptane in a synthetic silica porous medium at 22.5 °C and 1 bar, illustrate the accuracy of liquid-liquid interface and potential research and industrial applications of the technique. Liquid-liquid interfaces can be detected independently using both speed of sound and acoustic wave attenuation measurements. The precision of the interface location measurement is 300 μm. As complete scans can be performed at a rate of 1 Hz, phase separation kinetics and diffusion of liquids within porous media are readily tracked. The technique is expected to find application where the fluids or porous media are opaque to visible light and where other imaging techniques are not readily applied, or are too costly. A current limitation is that the acoustic probes must be cooled to less than 315 K in order for them to operate.

  17. Optimizing Satellite Communications With Adaptive and Phased Array Antennas

    NASA Technical Reports Server (NTRS)

    Ingram, Mary Ann; Romanofsky, Robert; Lee, Richard Q.; Miranda, Felix; Popovic, Zoya; Langley, John; Barott, William C.; Ahmed, M. Usman; Mandl, Dan

    2004-01-01

    A new adaptive antenna array architecture for low-earth-orbiting satellite ground stations is being investigated. These ground stations are intended to have no moving parts and could potentially be operated in populated areas, where terrestrial interference is likely. The architecture includes multiple, moderately directive phased arrays. The phased arrays, each steered in the approximate direction of the satellite, are adaptively combined to enhance the Signal-to-Noise and Interference-Ratio (SNIR) of the desired satellite. The size of each phased array is to be traded-off with the number of phased arrays, to optimize cost, while meeting a bit-error-rate threshold. Also, two phased array architectures are being prototyped: a spacefed lens array and a reflect-array. If two co-channel satellites are in the field of view of the phased arrays, then multi-user detection techniques may enable simultaneous demodulation of the satellite signals, also known as Space Division Multiple Access (SDMA). We report on Phase I of the project, in which fixed directional elements are adaptively combined in a prototype to demodulate the S-band downlink of the EO-1 satellite, which is part of the New Millennium Program at NASA.

  18. Improved Titanium Billet Inspection Sensitivity through Optimized Phased Array Design, Part I: Design Technique, Modeling and Simulation

    NASA Astrophysics Data System (ADS)

    Lupien, Vincent; Hassan, Waled; Dumas, Philippe

    2006-03-01

    Reductions in the beam diameter and pulse duration of focused ultrasound for titanium inspections are believed to result in a signal-to-noise ratio improvement for embedded defect detection. It has been inferred from this result that detection limits could be extended to smaller defects through a larger diameter, higher frequency transducer resulting in a reduced beamwidth and pulse duration. Using Continuum Probe Designer™ (Pat. Pending), a transducer array was developed for full coverage inspection of 8 inch titanium billets. The main challenge in realizing a large aperture phased array transducer for billet inspection is ensuring that the number of elements remains within the budget allotted by the driving electronics. The optimization technique implemented by Continuum Probe Designer™ yields an array with twice the aperture but the same number of elements as existing phased arrays for the same application. The unequal area element design was successfully manufactured and validated both numerically and experimentally. Part I of this two-part series presents the design, simulation and modeling steps, while Part II presents the experimental validation and comparative study to multizone.

  19. Low cost, electronically steered phased array for general aviation

    NASA Technical Reports Server (NTRS)

    Strickland, Peter C.

    1990-01-01

    This paper describes a multifaced, phased array antenna developed for general aviation satellite communications applications. The antenna design satisfies all INMARSAT Aeronautical SDM requirements. Unique features of this antenna include an integral LNA and diplexer, integral phase shifters which are shared among the array faces, a serial beam steering interface and low manufacturing cost.

  20. Beam-pointing errors of planar-phased arrays.

    NASA Technical Reports Server (NTRS)

    Carver, K. R.; Cooper, W. K.; Stutzman, W. L.

    1973-01-01

    Using both analytical and Monte Carlo techniques, beam-pointing errors of planar-phased arrays are analyzed. The obtained simple formulas for rms pointing errors are applicable to uniform planar arrays with both uniform and Gaussian uncorrelated phase-error distributions and for any arbitrary scan angle.

  1. Guided wave phased array beamforming and imaging in composite plates.

    PubMed

    Yu, Lingyu; Tian, Zhenhua

    2016-05-01

    This paper describes phased array beamforming using guided waves in anisotropic composite plates. A generic phased array algorithm is presented, in which direction dependent guided wave parameters and the energy skew effect are considered. This beamforming at an angular direction is achieved based on the classic delay-and-sum principle by applying phase delays to signals received at array elements and adding up the delayed signals. The phase delays are determined with the goal to maximize the array output at the desired direction and minimize it otherwise. For array characterization, the beam pattern of rectangular grid arrays in composite plates is derived. In addition to the beam pattern, the beamforming factor in terms of wavenumber distribution is defined to provide intrinsic explanations for phased array beamforming. The beamforming and damage detection in a composite plate are demonstrated using rectangular grid arrays made by a non-contact scanning laser Doppler vibrometer. Detection images of the composite plate with multiple surface defects at various directions are obtained. The results show that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures. PMID:26907891

  2. Array antennas design in dependence of element-phasing

    NASA Astrophysics Data System (ADS)

    Zichner, R.; Chandra, M.

    2009-05-01

    Array antennas are used in science as well as for commercial and military purposes. The used element antennas act in accordance to their desired uses, for example radars or stationer GPS satellites. Typical components are for example slotted waveguides, patches, yagi-antennas and helix-antennas. All these elements do stand out with their own characteristics based on their special applications. If these elements are formed into an array configuration, the effectiveness can be improved immensely. There is a relation between the array functions and the physical array properties like the element alignment (linear, planar, circular), distances between the elements and so on. Among the physical properties there are other attributes like phase or amplitude coefficients, which are of great significance. The aim of this study was to provide an insight into the problem of array design, as far as the antenna element phase is concerned. Along with this, array radiation characteristics effects are presented. With the help of the extracted cognitions beam forming behaviour can be shown and the array phase behaviour can be analysed. One of the main applications is to simulate the array characteristics, like the radiation characteristic or the gain, for displacements of the array feeding point. A software solution that simulates the phase shift of a given array pattern is sought to adjust the feeding point.

  3. Reconfigurable Wave Velocity Transmission Lines for Phased Arrays

    NASA Technical Reports Server (NTRS)

    Host, Nick; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix

    2013-01-01

    Phased array antennas showcase many advantages over mechanically steered systems. However, they are also more complex, heavy and most importantly costly. This presentation paper presents a concept which overcomes these detrimental attributes by eliminating all of the phase array backend (including phase shifters). Instead, a wave velocity reconfigurable transmission line is used in a series fed array arrangement to allow phase shifting with one small (100mil) mechanical motion. Different configurations of the reconfigurable wave velocity transmission line are discussed and simulated and experimental results are presented.

  4. Image-guided ultrasound phased arrays are a disruptive technology for non-invasive therapy

    NASA Astrophysics Data System (ADS)

    Hynynen, Kullervo; Jones, Ryan M.

    2016-09-01

    Focused ultrasound offers a non-invasive way of depositing acoustic energy deep into the body, which can be harnessed for a broad spectrum of therapeutic purposes, including tissue ablation, the targeting of therapeutic agents, and stem cell delivery. Phased array transducers enable electronic control over the beam geometry and direction, and can be tailored to provide optimal energy deposition patterns for a given therapeutic application. Their use in combination with modern medical imaging for therapy guidance allows precise targeting, online monitoring, and post-treatment evaluation of the ultrasound-mediated bioeffects. In the past there have been some technical obstacles hindering the construction of large aperture, high-power, densely-populated phased arrays and, as a result, they have not been fully exploited for therapy delivery to date. However, recent research has made the construction of such arrays feasible, and it is expected that their continued development will both greatly improve the safety and efficacy of existing ultrasound therapies as well as enable treatments that are not currently possible with existing technology. This review will summarize the basic principles, current statures, and future potential of image-guided ultrasound phased arrays for therapy.

  5. Image-guided ultrasound phased arrays are a disruptive technology for non-invasive therapy.

    PubMed

    Hynynen, Kullervo; Jones, Ryan M

    2016-09-01

    Focused ultrasound offers a non-invasive way of depositing acoustic energy deep into the body, which can be harnessed for a broad spectrum of therapeutic purposes, including tissue ablation, the targeting of therapeutic agents, and stem cell delivery. Phased array transducers enable electronic control over the beam geometry and direction, and can be tailored to provide optimal energy deposition patterns for a given therapeutic application. Their use in combination with modern medical imaging for therapy guidance allows precise targeting, online monitoring, and post-treatment evaluation of the ultrasound-mediated bioeffects. In the past there have been some technical obstacles hindering the construction of large aperture, high-power, densely-populated phased arrays and, as a result, they have not been fully exploited for therapy delivery to date. However, recent research has made the construction of such arrays feasible, and it is expected that their continued development will both greatly improve the safety and efficacy of existing ultrasound therapies as well as enable treatments that are not currently possible with existing technology. This review will summarize the basic principles, current statures, and future potential of image-guided ultrasound phased arrays for therapy. PMID:27494561

  6. A 63 element 1.75 dimensional ultrasound phased array for the treatment of benign prostatic hyperplasia

    PubMed Central

    Saleh, Khaldon Y; Smith, Nadine Barrie

    2005-01-01

    Background Prostate cancer and benign prostatic hyperplasia are very common diseases in older American men, thus having a reliable treatment modality for both diseases is of great importance. The currently used treating options, mainly surgical ones, have numerous complications, which include the many side effects that accompany such procedures, besides the invasive nature of such techniques. Focused ultrasound is a relatively new treating modality that is showing promising results in treating prostate cancer and benign prostatic hyperplasia. Thus this technique is gaining more attention in the past decade as a non-invasive method to treat both diseases. Methods In this paper, the design, construction and evaluation of a 1.75 dimensional ultrasound phased array to be used for treating prostate cancer and benign prostatic hyperplasia is presented. With this array, the position of the focus can be controlled by changing the electrical power and phase to the individual elements for electronically focusing and steering in a three dimensional volume. The array was designed with a maximum steering angle of ± 13.5° in the transverse direction and a maximum depth of penetration of 11 cm, which allows the treatment of large prostates. The transducer piezoelectric ceramic, matching layers and cable impedance have been designed for maximum power transfer to tissue. Results To verify the capability of the transducer for focusing and steering, exposimetry was performed and the results correlated well with the calculated field. Ex vivo experiments using bovine tissue were performed with various lesion sizes and indicated the capability of the transducer to ablate tissue using short sonications. Conclusion A 1.75 dimensional array, that overcame the drawbacks associated with one-dimensional arrays, has been designed, built and successfully tested. Design issues, such as cable and ceramic capacitances, were taken into account when designing this array. The final prototype

  7. Phase-locked semiconductor laser array with separate contacts

    NASA Technical Reports Server (NTRS)

    Katz, J.; Kapon, E.; Lindsey, C.; Margalit, S.; Shreter, U.; Yariv, A.

    1983-01-01

    A new monolithic phase-locked semiconductor laser array has been fabricated. Employing two-level metallization, each of the eight elements in the array has a separate contact, thus making it possible to compensate for device nonuniformities and control the near-field and far-field patterns. Threshold currents are approximately 60 mA for each 5-micron-wide laser in the array. Phase locking has been observed via the narrowing of the far-field pattern. Experimental results are compared to those obtained from the same arrays operated with all the lasers connected in parallel.

  8. Microwave power transmitting phased array antenna research project

    NASA Technical Reports Server (NTRS)

    Dickinson, R. M.

    1978-01-01

    An initial design study and the development results of an S band RF power transmitting phased array antenna experiment system are presented. The array was to be designed, constructed and instrumented to permit wireless power transmission technology evaluation measurements. The planned measurements were to provide data relative to the achievable performance in the state of the art of flexible surface, retrodirective arrays, as a step in technically evaluating the satellite power system concept for importing to earth, via microwave beams, the nearly continuous solar power available in geosynchronous orbit. Details of the microwave power transmitting phased array design, instrumentation approaches, system block diagrams, and measured component and breadboard characteristics achieved are presented.

  9. Coherent optical monolithic phased-array antenna steering system

    DOEpatents

    Hietala, Vincent M.; Kravitz, Stanley H.; Vawter, Gregory A.

    1994-01-01

    An optical-based RF beam steering system for phased-array antennas comprising a photonic integrated circuit (PIC). The system is based on optical heterodyning employed to produce microwave phase shifting by a monolithic PIC constructed entirely of passive components. Microwave power and control signal distribution to the antenna is accomplished by optical fiber, permitting physical separation of the PIC and its control functions from the antenna. The system reduces size, weight, complexity, and cost of phased-array antenna systems.

  10. Repulsive Synchronization in an Array of Phase Oscillators

    NASA Astrophysics Data System (ADS)

    Tsimring, L. S.; Rulkov, N. F.; Larsen, M. L.; Gabbay, M.

    2005-06-01

    We study the dynamics of a repulsively coupled array of phase oscillators. For an array of globally coupled identical oscillators, repulsive coupling results in a family of synchronized regimes characterized by zero mean field. If the number of oscillators is sufficiently large, phase locking among oscillators is destroyed, independently of the coupling strength, when the oscillators’ natural frequencies are not the same. In locally coupled networks, however, phase locking occurs even for nonidentical oscillators when the coupling strength is sufficiently strong.

  11. Application of a 3d Smart Flexible Phased-Array to Piping Inspection

    NASA Astrophysics Data System (ADS)

    Toullelan, G.; Casula, O.; Abittan, E.; Dumas, P.

    2008-02-01

    The piping inspection in nuclear power plants is mainly performed in contact with ultrasonic wedge transducers. During the scanning, the fixed shape of the wedges cannot conform to the irregular surfaces and complex geometries of the components (butt weld, nozzle, elbow). The surface irregularities lead to thickness variations of the coupling medium that result in beam distortions and losses of sensitivity. A 3-D ultrasonic flexible phased-array is presented here and applied to the ultrasonic inspection of a welded pipe. This example of a complex geometry inspection is typical of the field of application for such sensor. The phased-array probe is flexible to conform to a complex profile and to minimize the thickness of the coupling layer. The independent piezoelectric elements composing the radiating surface are mechanically assembled to build an articulated structure. A profilometer, embedded in the transducer, measures the local surface distortion allowing to compute in real-time the optimized delay laws and to compensate the distortions of the 2D or 3D profiles. Those delay laws transferred to the UT-acquisition system are applied in real-time to the piezoelectric elements. The experiments presented here aim to determine the detection abilities of this technique using multi-shot configurations (e.g. angular scanning, several points focusing).

  12. Monolithic and integrated phased array antennas

    NASA Astrophysics Data System (ADS)

    Schaubert, Daniel H.; Pozar, David M.

    Some of the problems relevant to the design of monolithic and integrated arrays are examined. In particular, attention is given to electrical and mechanical design considerations, restrictions they impose on the choice of elements and architecture of integrated arrays, and elements that can alleviate one or more of these restrictions. Monolithic array designs are compared with some multiple-layer and two-sided designs using such criteria as scan range, bandwidth, substrate size and configuration, polarization, and feed line radiation. Broadside radiating elements, such as microstrip dipoles and patches, as well as end-fire radiating slots are considered.

  13. Evaluation of adhesive-free crossed-electrode poly(vinylidene fluoride) copolymer array transducers for high frequency imaging

    NASA Astrophysics Data System (ADS)

    Wagle, Sanat; Decharat, Adit; Habib, Anowarul; Ahluwalia, Balpreet S.; Melandsø, Frank

    2016-07-01

    High frequency crossed-electrode transducers have been investigated, both as single and dual layer transducers. Prototypes of these transducers were developed for 4 crossed lines (yielding 16 square elements) on a polymer substrate, using a layer-by-layer deposition method for poly(vinylidene fluoride–trifluoroethylene) [P(VDF–TrFE)] with intermediate sputtered electrodes. The transducer was characterized using various methods [LCR analyzer, a pulse–echo experimental setup, and a numerical Finite element method (FEM) model] and evaluated in terms of uniformity of bandwidth and acoustical energy output. All 16 transducer elements produced broad-banded ultrasonic spectra with small variation in central frequency and ‑6 dB bandwidth. The frequency responses obtained experimentally were verified using a numerical model.

  14. Phased-array sources based on nonlinear metamaterial nanocavities

    SciTech Connect

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P.; Liu, Sheng; Luk, Ting S.; Kadlec, Emil Andrew; Shaner, Eric A.; Klem, John Frederick; Sinclair, Michael B.; Brener, Igal

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (~5 μm): a beam splitter and a polarizing beam splitter. As a result, proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.

  15. Phased-array sources based on nonlinear metamaterial nanocavities

    NASA Astrophysics Data System (ADS)

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P.; Liu, Sheng; Luk, Ting S.; Kadlec, Emil A.; Shaner, Eric A.; Klem, John F.; Sinclair, Michael B.; Brener, Igal

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (~5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.

  16. Diffraction-Coupled, Phase-Locked Semiconductor Laser Array

    NASA Technical Reports Server (NTRS)

    Katz, Joseph; Yariv, Amnon; Margalit, Shlomo

    1988-01-01

    Stable, narrow far field produced. Array of lasers fabricated on single chip. Individual laser waveguides isolated from each other except in end portions, where diffraction coupling takes place. Radiation pattern far from laser array has single, sharp central lobe when all lasers operate in phase with each other. Shape of lobe does not vary appreciably with array current. Applications include recording, printing, and range finding.

  17. Two transducer formula for more precise determination of ultrasonic phase velocity from standing wave measurements

    NASA Technical Reports Server (NTRS)

    Ringermacher, H. I.; Moerner, W. E.; Miller, J. G.

    1974-01-01

    A two transducer correction formula valid for both solid and liquid specimens is presented. Using computer simulations of velocity measurements, the accuracy and range of validity of the results are discussed and are compared with previous approximations.

  18. Frequency translating phase conjugation circuit for active retrodirective antenna array

    NASA Astrophysics Data System (ADS)

    Chernoff, R.

    1980-11-01

    An active retrodirective antenna array which has central phasing from a reference antenna element through a "tree" structured network of transmission lines utilizes a number of phase conjugate circuits (PCCs) at each node and a phase reference regeneration circuit (PRR) at each node except the initial node. Each node virtually coincides with an element of the array. A PCC generates the exact conjugate phase of an incident signal using a phase locked loop which combines the phases in an up converter, divides the sum by 2 and mixes the result with the phase in a down converter for phase detection. The PRR extracts the phase from the conjugate phase. Both the PCC and the PRR are not only exact but also free from mixer degeneracy.

  19. Phased array-fed antenna configuration study: Technology assessment

    NASA Technical Reports Server (NTRS)

    Croswell, W. F.; Ball, D. E.; Taylor, R. C.

    1983-01-01

    Spacecraft array fed reflector antenna systems were assessed for particular application to a multiple fixed spot beam/multiple scanning spot beam system. Reflector optics systems are reviewed in addition to an investigation of the feasibility of the use of monolithic microwave integrated circuit power amplifiers and phase shifters in each element of the array feed.

  20. Objective Assessment and Design Improvement of a Staring, Sparse Transducer Array by the Spatial Crosstalk Matrix for 3D Photoacoustic Tomography

    PubMed Central

    Kosik, Ivan; Raess, Avery

    2015-01-01

    Accurate reconstruction of 3D photoacoustic (PA) images requires detection of photoacoustic signals from many angles. Several groups have adopted staring ultrasound arrays, but assessment of array performance has been limited. We previously reported on a method to calibrate a 3D PA tomography (PAT) staring array system and analyze system performance using singular value decomposition (SVD). The developed SVD metric, however, was impractical for large system matrices, which are typical of 3D PAT problems. The present study consisted of two main objectives. The first objective aimed to introduce the crosstalk matrix concept to the field of PAT for system design. Figures-of-merit utilized in this study were root mean square error, peak signal-to-noise ratio, mean absolute error, and a three dimensional structural similarity index, which were derived between the normalized spatial crosstalk matrix and the identity matrix. The applicability of this approach for 3D PAT was validated by observing the response of the figures-of-merit in relation to well-understood PAT sampling characteristics (i.e. spatial and temporal sampling rate). The second objective aimed to utilize the figures-of-merit to characterize and improve the performance of a near-spherical staring array design. Transducer arrangement, array radius, and array angular coverage were the design parameters examined. We observed that the performance of a 129-element staring transducer array for 3D PAT could be improved by selection of optimal values of the design parameters. The results suggested that this formulation could be used to objectively characterize 3D PAT system performance and would enable the development of efficient strategies for system design optimization. PMID:25875177

  1. Preliminary in vivo breast vibro-acoustography results with a quasi 2-dimensional array transducer: a step forward towards clinical applications

    PubMed Central

    Mehrmohammadi, Mohammad; Fazzio, Robert T.; Whaley, Dana H.; Pruthi, Sandhya; Kinnick, Randall R.; Fatemi, Mostafa; Alizad, Azra

    2014-01-01

    We have previously investigated the application of a novel imaging modality, vibro-acoustography (VA) using an annular confocal transducer (confocal VA), integrated into a clinical prone stereotactic mammography system to detect various breast abnormalities. To shorten the scanning time and provide improved coverage of the breast, we have evolved our imaging system by implementing VA on a clinical ultrasound scanner equipped with a “quasi-2-dimensional” array transducer. We call this technique “quasi-2D vibro-acoustography” (Q2DVA). A clinical ultrasound scanner (GE Vivid 7) was modified to perform both ultrasound (US) imaging and VA using an array transducer consisting of a matrix of 12 rows by 70 columns of ultrasound elements. The newly designed system was used to perform VA on patients with either benign or cancerous lesions. Our results indicate that benign and malignant solid breast lesions were easily detected using our newly modified VA system. It was also possible to detect micro-calcifications within the breast. Our results suggest that with further development, Q2DVA could provide high-resolution diagnostic information in the clinical setting and may be used either as a stand-alone or as a complementary tool in support of other clinical imaging modalities. PMID:25438862

  2. Investigation and optimization of a finite element simulation of transducer array systems for 3D ultrasound computer tomography with respect to electrical impedance characteristics

    NASA Astrophysics Data System (ADS)

    Kohout, B.; Pirinen, J.; Ruiter, N. V.

    2012-03-01

    The established standard screening method to detect breast cancer is X-ray mammography. However X-ray mammography often has low contrast for tumors located within glandular tissue. A new approach is 3D Ultrasound Computer Tomography (USCT), which is expected to detect small tumors at an early stage. This paper describes the development, improvement and the results of Finite Element Method (FEM) simulations of the Transducer Array System (TAS) used in our 3D USCT. The focus of this work is on researching the influence of meshing and material parameters on the electrical impedance curves. Thereafter, these findings are used to optimize the simulation model. The quality of the simulation was evaluated by comparing simulated impedance characteristics with measured data of the real TAS. The resulting FEM simulation model is a powerful tool to analyze and optimize transducer array systems applied for USCT. With this simulation model, the behavior of TAS for different geometry modifications was researched. It provides a means to understand the acoustical performances inside of any ultrasound transducer represented by its electrical impedance characteristic.

  3. A 32-GHz phased array transmit feed for spacecraft telecommunications

    NASA Technical Reports Server (NTRS)

    Lee, K. A.; Rascoe, D. L.; Crist, R. A.; Huang, J.; Wamhof, P. D.; Lansing, F. S.

    1992-01-01

    A 21-element phased array transmit feed was demonstrated as part of an effort to develop and evaluate state-of-the-art transmitter and receiver components at 32 and 34 GHz for future deep-space missions. Antenna pattern measurements demonstrating electronic beam steering of the two-dimensional array are reported and compared with predictions based on measured performance of MMIC-based phase shifter and amplifier modules and Vivaldi slotline radiating elements.

  4. MSAT mobile electronically steered phased array antenna development

    NASA Technical Reports Server (NTRS)

    Schmidt, Fred

    1988-01-01

    The Mobile Satellite Experiment (MSAT-X) breadboard antenna design demonstrates the feasibility of using a phased array in a mobile satellite application. An electronically steerable phased array capable of tracking geosynchronous satellites from anywhere in the Continental United States has been developed. The design is reviewed along with the test data. Cost analysis are presented which indicate that this design can be produced at a cost of $1620 per antenna.

  5. The effect of variation in phased array element performance for Non-Destructive Evaluation (NDE).

    PubMed

    Duxbury, David; Russell, Jonathan; Lowe, Michael

    2013-08-01

    This paper reports the results of an investigation into the effects of phased array element performance on ultrasonic beam integrity. This investigation has been performed using an array beam model based on Huygens' principle to independently investigate the effects of element sensitivity and phase, and non-functioning elements via Monte Carlo simulation. The purpose of this work is to allow a new method of array calibration for Non-Destructive Evaluation (NDE) to be adopted that focuses on probe integrity rather than beam integrity. This approach is better suited to component inspections that utilise Full Matrix Capture (FMC) to record data as the calibration routine is uncoupled from the beams that the array is required to produce. For this approach to be adopted specifications must be placed on element performance that guarantee beam quality without carrying out any beam forming. The principal result of this investigation is that the dominant outcome following variations in array element performance is the introduction of beam artefacts such as main beam broadening, raising of the noise floor of the ultrasonic field, and the enlargement or creation of side lobes. Specifications for practical allowable limits of element sensitivity, element phase, and the number of non-functioning elements have been suggested based on a minimum amplitude difference between beam artefacts and the main beam peak of 8 dB. Simulation at a number of centre frequencies has led to a recommendation that the product of transducer bandwidth and maximum phase error should be kept below 0.051 and 0.035 for focused and plane beams respectively. Element sensitivity should be within 50% of mean value of the aperture, and no more than 9% of the elements should be non-functioning. PMID:23337826

  6. Jet Noise Source Localization Using Linear Phased Array

    NASA Technical Reports Server (NTRS)

    Agboola, Ferni A.; Bridges, James

    2004-01-01

    A study was conducted to further clarify the interpretation and application of linear phased array microphone results, for localizing aeroacoustics sources in aircraft exhaust jet. Two model engine nozzles were tested at varying power cycles with the array setup parallel to the jet axis. The array position was varied as well to determine best location for the array. The results showed that it is possible to resolve jet noise sources with bypass and other components separation. The results also showed that a focused near field image provides more realistic noise source localization at low to mid frequencies.

  7. MEMS-based phased arrays for army applications

    NASA Astrophysics Data System (ADS)

    Ruffin, Paul B.; Holt, James C.; Mullins, James H.; Hudson, Tracy; Rock, Janice

    2007-04-01

    The Army Aviation and Missile Research, Development, and Engineering Center (AMRDEC) initiated a research and development project several years ago to develop Micro Electro-Mechanical Systems (MEMS)-based phased arrays to provide rapid beam steering for sensors, optical and Radio Frequency (RF) missile seekers, and RF communication links. In particular, the joint AMRDEC/Army Research Laboratory (ARL) project, which leverages low-cost phased array components developed under the Defense Advanced Research Projects Agency (DARPA) Low Cost Cruise Missile Defense (LCCMD) project, is developing RF switches, phase shifters, and passive phased sub-arrays to provide a fast scanning capability for pointing, acquisition, tracking, and data communication; and rugged, optical MEMS-based phased arrays to be employed in small volume, low-cost Laser Detection and Ranging (LADAR) seekers. The current status of the project is disclosed in this paper. Critical technical challenges, which include design and fabrication of the RF switches and phase shifters, design and fabrication of micro lens arrays, control of beam steering, scanning angular resolution and array losses, are discussed. Our approach to overcoming the technical barriers and achieving required performance is also discussed. Finally, the validity of a MEMS technology approach against competing low cost technologies is presented.

  8. Model of a Piezoelectric Transducer

    NASA Technical Reports Server (NTRS)

    Goodenow, Debra

    2004-01-01

    It's difficult to control liquid and gas in propellant tanks in zero gravity. A possible a design would utilize acoustic liquid manipulation (ALM) technology which uses ultrasonic beams conducted through a liquid and solid media, to push gas bubbles in the liquid to desirable locations. We can propel and control the bubble with acoustic radiation pressure by aiming the acoustic waves on the bubble s surface. This allows us to design a so called smart tank in which the ALM devices transfer the gas to the outer wall of the tank and isolating the liquid in the center. Because the heat transfer rate of a gas is lower of that of the liquid it would substantially decrease boil off and provide of for a longer storage life. The ALM beam is composed of little wavelets which are individual waves that constructively interfere with each other to produce a single, combined acoustic wave front. This is accomplished by using a set of synchronized ultrasound transducers arranged in an array. A slight phase offset of these elements allows us to focus and steer the beam. The device that we are using to produce the acoustic beam is called the piezoelectric transducer. This device converts electrical energy to mechanical energy, which appears in the form of acoustic energy. Therefore the behavior of the device is dependent on both the mechanical characteristics, such as its density, cross-sectional area, and its electrical characteristics, such as, electric flux permittivity and coupling factor. These devices can also be set up in a number of modes which are determined by the way the piezoelectric device is arranged, and the shape of the transducer. For this application we are using the longitudinal or thickness mode for our operation. The transducer also vibrates in the lateral mode, and one of the goals of my project is to decrease the amount of energy lost to the lateral mode. To model the behavior of the transducers I will be using Pspice, electric circuit modeling tool, to

  9. Large Phased Array Radar Using Networked Small Parabolic Reflectors

    NASA Technical Reports Server (NTRS)

    Amoozegar, Farid

    2006-01-01

    Multifunction phased array systems with radar, telecom, and imaging applications have already been established for flat plate phased arrays of dipoles, or waveguides. In this paper the design trades and candidate options for combining the radar and telecom functions of the Deep Space Network (DSN) into a single large transmit array of small parabolic reflectors will be discussed. In particular the effect of combing the radar and telecom functions on the sizes of individual antenna apertures and the corresponding spacing between the antenna elements of the array will be analyzed. A heterogeneous architecture for the DSN large transmit array is proposed to meet the radar and telecom requirements while considering the budget, scheduling, and strategic planning constrains.

  10. Simple tools for simulating phased array focal laws on 3D solids

    NASA Astrophysics Data System (ADS)

    Weber, Walter H.; Mair, H. Douglas; Frazer, Leigh

    2001-04-01

    This paper reports our progress on the development of a three-dimensional raytracing program that can simulate the focal laws of a phased array system. The modeled transducer is divided into elements of a given length, width and inter-element gap distance. Each focal law to be modeled requires a steering angle, focal length and selection of which groups of elements are transmitting and receiving. Electronic scanning is simulated by stepping through a series of predefined focal laws. The program phase shifts and sums the received rays at each element based on the properties of the currently-active focal law. Simulated A-scans are constructed from the received rays which appear animated as the beam is swept. Beam profiles can also be generated that show the primary forward beam and energy in the side lobes. The work is based on Imagine3D ultrasonic simulation software and the dedicated efforts of Doug Mair and Leigh Frazer.

  11. The frequency response of phased-array antennas

    NASA Astrophysics Data System (ADS)

    Brock, B. C.

    1989-02-01

    The phased-array antenna will be examined from the point of view of effects caused by changes in frequency. Both simple linear arrays and the more complex conformal array are examined. For the conformal array, a comparison between a corporate-feed structure and a row series-feed structure is included. There are two primary effects which will be discussed: beam-pointing errors and distortion of large bandwidth signals. A formula for estimating the operating or tunable array bandwidth for narrow-bandwidth signals is derived. An expression for the wide-bandwidth-signal transfer function is also obtained and examined. It will be shown that the transfer function depends both on the array scan angle and the position within the mainbeam.

  12. The frequency response of phased-array antennas

    SciTech Connect

    Brock, B.C.

    1989-02-01

    The phased-array antenna will be examined from the point of view of effects caused by changes in frequency. Both simple linear arrays and the more complex conformal array are examined. For the conformal array, a comparison between a corporate-feed structure and a row series-feed structure is included. There are two primary effects which will be discussed: beam-pointing errors and distortion of large bandwidth signals. A formula for estimating the operating or tunable array bandwidth for narrow-bandwidth signals is derived. An expression for the wide-bandwidth-signal transfer function is also obtained and examined. It will be shown that the transfer function depends both on the array scan angle and the position within the mainbeam. 25 figs.

  13. A single-chip 32-channel analog beamformer with 4-ns delay resolution and 768-ns maximum delay range for ultrasound medical imaging with a linear array transducer.

    PubMed

    Um, Ji-Yong; Kim, Yoon-Jee; Cho, Seong-Eun; Chae, Min-Kyun; Kim, Byungsub; Sim, Jae-Yoon; Park, Hong-June

    2015-02-01

    A single-chip 32-channel analog beamformer is proposed. It achieves a delay resolution of 4 ns and a maximum delay range of 768 ns. It has a focal-point based architecture, which consists of 7 sub-analog beamformers (sub-ABF). Each sub-ABF performs a RX focusing operation for a single focal point. Seven sub-ABFs perform a time-interleaving operation to achieve the maximum delay range of 768 ns. Phase interpolators are used in sub-ABFs to generate sampling clocks with the delay resolution of 4 ns from a low frequency system clock of 5 MHz. Each sub-ABF samples 32 echo signals at different times into sampling capacitors, which work as analog memory cells. The sampled 32 echo signals of each sub-ABF are originated from one target focal point at one instance. They are summed at one instance in a sub-ABF to perform the RX focusing for the target focal point. The proposed ABF chip has been fabricated in a 0.13- μ m CMOS process with an active area of 16 mm (2). The total power consumption is 287 mW. In measurement, the digital echo signals from a commercial ultrasound medical imaging machine were applied to the fabricated chip through commercial DAC chips. Due to the speed limitation of the DAC chips, the delay resolution was relaxed to 10 ns for the real-time measurement. A linear array transducer with no steering operation is used in this work. PMID:25069119

  14. Ka-Band Multibeam Aperture Phased Array Being Developed

    NASA Technical Reports Server (NTRS)

    Reinhart, Richard C.; Kacpura, Thomas J.

    2004-01-01

    Phased-array antenna systems offer many advantages to low-Earth-orbiting satellite systems. Their large scan angles and multibeam capabilities allow for vibration-free, rapid beam scanning and graceful degradation operation for high rate downlink of data to users on the ground. Technology advancements continue to reduce the power, weight, and cost of these systems to make phased arrays a competitive alternative in comparison to the gimbled reflector system commonly used in science missions. One effort to reduce the cost of phased arrays is the development of a Ka-band multibeam aperture (MBA) phased array by Boeing Corporation under a contract jointly by the NASA Glenn Research Center and the Office of Naval Research. The objective is to develop and demonstrate a space-qualifiable dual-beam Ka-band (26.5-GHz) phased-array antenna. The goals are to advance the state of the art in Ka-band active phased-array antennas and to develop and demonstrate multibeam transmission technology compatible with spacecraft in low Earth orbit to reduce the cost of future missions by retiring certain development risks. The frequency chosen is suitable for space-to-space and space-to-ground communication links. The phased-array antenna has a radiation pattern designed by combining a set of individual radiating elements, optimized with the type of radiating elements used, their positions in space, and the amplitude and phase of the currents feeding the elements. This arrangement produces a directional radiation pattern that is proportional to the number of individual radiating elements. The arrays of interest here can scan the main beam electronically with a computerized algorithm. The antenna is constructed using electronic components with no mechanical parts, and the steering is performed electronically, without any resulting vibration. The speed of the scanning is limited primarily by the control electronics. The radiation performance degrades gracefully if a portion of the elements

  15. Self compensating phase control for Venetian blind steering in phased arrays.

    NASA Astrophysics Data System (ADS)

    Pohle, R. H.; Stubbs, D. M.

    1988-10-01

    The term "self compensating phase control" is a name for the approach to use the rotation of each array element (e.g. telescopes) in the phased array to provide most of the large optical path length shift required for phasing during a phased array look angle shift by individual telescope slew (i.e. venetian blind steering). The optical train configuration discussed here provides about 97% of the optical path length compensation required for a slew of ±20 degrees from the array normal. This greatly reduces the amplitude required of the piston control mirror.

  16. Coplanar waveguide feeds for phased array antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1992-01-01

    The design and performance of the following coplanar waveguide (CPW) microwave distribution networks for linear as well as circularly polarized microstrip patches and printed dipole arrays is presented: (1) CPW/microstrip line feed; (2) CPW/balanced stripline feed; (3) CPW/slotline feed; (4) grounded CPW (GCPW)/balanced coplanar stripline feed; and (5) CPW/slot coupled feed. Typical measured radiation patterns are presented, and their relative advantages and disadvantages are compared.

  17. Coplanar waveguide feeds for phased array antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1991-01-01

    The design and performance is presented of the following coplanar waveguides (CPW) microwave distribution networks for linear as well as circularly polarized microstrip patches and dipole arrays: (1) CPW/microstrip line feed; (2) CPW/balanced stripline feed; (3) CPW/slotline feed; (4) grounded CPW/balanced coplanar stripline feed; and (5) CPW/slot coupled feed. Typical measured radiation patterns are presented, and their relative advantages and disadvantages are compared.

  18. Coplanar waveguide feeds for phased array antennas

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Lee, Richard Q.

    1991-01-01

    The design and performance is presented of the following Coplanar Waveguides (CPW) microwave distribution networks for linear as well as circularly polarized microstrip patches and dipole arrays: (1) CPW/Microstrip Line feed; (2) CPW/Balanced Stripline feed; (3) CPW/Slotline feed; (4) Grounded CPW/Balanced coplanar stripline feed; and (5) CPW/Slot coupled feed. Typical measured radiation patterns are presented, and their relative advantages and disadvantages are compared.

  19. Coplanar waveguide feeds for phased array antennas

    NASA Astrophysics Data System (ADS)

    Simons, Rainee N.; Lee, Richard Q.

    1991-09-01

    The design and performance is presented of the following coplanar waveguides (CPW) microwave distribution networks for linear as well as circularly polarized microstrip patches and dipole arrays: (1) CPW/microstrip line feed; (2) CPW/balanced stripline feed; (3) CPW/slotline feed; (4) grounded CPW/balanced coplanar stripline feed; and (5) CPW/slot coupled feed. Typical measured radiation patterns are presented, and their relative advantages and disadvantages are compared.

  20. Coplanar waveguide feeds for phased array antennas

    NASA Astrophysics Data System (ADS)

    Simons, Rainee N.; Lee, Richard Q.

    1992-08-01

    The design and performance of the following coplanar waveguide (CPW) microwave distribution networks for linear as well as circularly polarized microstrip patches and printed dipole arrays is presented: (1) CPW/microstrip line feed; (2) CPW/balanced stripline feed; (3) CPW/slotline feed; (4) grounded CPW (GCPW)/balanced coplanar stripline feed; and (5) CPW/slot coupled feed. Typical measured radiation patterns are presented, and their relative advantages and disadvantages are compared.

  1. Coplanar waveguide feeds for phased array antennas

    NASA Astrophysics Data System (ADS)

    Simons, Rainee N.; Lee, Richard Q.

    1991-09-01

    The design and performance is presented of the following Coplanar Waveguides (CPW) microwave distribution networks for linear as well as circularly polarized microstrip patches and dipole arrays: (1) CPW/Microstrip Line feed; (2) CPW/Balanced Stripline feed; (3) CPW/Slotline feed; (4) Grounded CPW/Balanced coplanar stripline feed; and (5) CPW/Slot coupled feed. Typical measured radiation patterns are presented, and their relative advantages and disadvantages are compared.

  2. Optical phased arrays with evanescently-coupled antennas

    DOEpatents

    Sun, Jie; Watts, Michael R; Yaacobi, Ami; Timurdogan, Erman

    2015-03-24

    An optical phased array formed of a large number of nanophotonic antenna elements can be used to project complex images into the far field. These nanophotonic phased arrays, including the nanophotonic antenna elements and waveguides, can be formed on a single chip of silicon using complementary metal-oxide-semiconductor (CMOS) processes. Directional couplers evanescently couple light from the waveguides to the nanophotonic antenna elements, which emit the light as beams with phases and amplitudes selected so that the emitted beams interfere in the far field to produce the desired pattern. In some cases, each antenna in the phased array may be optically coupled to a corresponding variable delay line, such as a thermo-optically tuned waveguide or a liquid-filled cell, which can be used to vary the phase of the antenna's output (and the resulting far-field interference pattern).

  3. Remoting alternatives for a multiple phased-array antenna network

    NASA Astrophysics Data System (ADS)

    Shi, Zan; Foshee, James J.

    2001-10-01

    Significant improvements in technology have made phased array antennas an attractive alternative to the traditional dish antenna for use on wide body airplanes. These improvements have resulted in reduced size, reduced cost, reduced losses in the transmit and receive channels (simplifying the design), a significant extension in the bandwidth capability, and an increase in the functional capability. Flush mounting (thus reduced drag) and rapid beam switching are among the evolving desirable features of phased array antennas. Beam scanning of phased array antennas is limited to +/-45 degrees at best and therefore multiple phased array antennas would need to be used to insure instantaneous communications with any ground station (stations located at different geographical locations on the ground) and with other airborne stations. The exact number of phased array antennas and the specific installation location of each antenna on the wide body airplane would need to be determined by the specific communication requirements, but it is conceivable as many as five phased array antennas may need to be used to provide the required coverage. Control and switching of these antennas would need to be accomplished at a centralized location on the airplane and since these antennas would be at different locations on the airplane an efficient scheme of remoting would need to be used. To save in cost and keep the phased array antennas as small as possible the design of the phased array antennas would need to be kept simple. A dish antenna and a blade antenna (small size) could also be used to augment the system. Generating the RF signals at the central location and then using RF cables or waveguide to get the signal to any given antenna could result in significant RF losses. This paper will evaluate a number of remoting alternatives to keep the system design simple, reduce system cost, and utilize the functional capability of networking multiple phased array antennas on a wide body

  4. Interferometric study on Gouy phase anomaly of microlens array

    NASA Astrophysics Data System (ADS)

    Kim, Myun-Sik; Scharf, Toralf; Noell, Wilfried; Herzig, Hans Peter; Voelkel, Reinhard

    2015-03-01

    We investigate the Gouy phase anomaly of light in the focus of refractive plano-convex microlens arrays by using longitudinal-differential (LD) interferometry and a finite-difference time-domain (FDTD) simulation. We put emphasis on determining the amount of the Gouy phase shift for the line focus of the cylindrical lens and the point focus of the spherical lens. We discuss additional phase structures caused by diffraction, which lead to the discrepancy from the conventional Gouy phase shift.

  5. On the Precision of Time-of-Flight Shear Wave Speed Estimation in Homogeneous Soft Solids: Initial Results using a Matrix Array Transducer

    PubMed Central

    Wang, Michael; Byram, Brett; Palmeri, Mark; Rouze, Ned; Nightingale, Kathryn

    2013-01-01

    A system capable of tracking radiation force induced shear wave propagation in a 3D volume using ultrasound is presented. In contrast to existing systems, which use 1D array transducers, a 2D matrix array is used for tracking shear wave displacements. A separate single element transducer is used for radiation force excitation. This system allows shear wave propagation in all directions away from the push to be observed. It is shown that for a limit of 64 tracking beams, by placing the beams at the edges of the measurement region of interest (ROI) at multiple directions from the push, time-of-flight (TOF) shear wave speed (SWS) measurement uncertainty can theoretically be reduced by 40% compared to equally spacing the tracking beams within the ROI along a single plane, as is typical when using a 1D array for tracking. This was verified by simulation, and a reduction of 30% was experimentally observed on a homogeneous phantom. Analytical expressions are presented for the relationship between TOF SWS measurement uncertainty and various shear wave imaging parameters. It is shown that TOF SWS uncertainty is inversely proportional to ROI size, and inversely proportional to the square root of the number of tracking locations for a given distribution of beam locations relative to the push. TOF SWS uncertainty is shown to increase with the square of the SWS, indicating that TOF SWS measurements are intrinsically less precise for stiffer materials. PMID:23549536

  6. Simple Array Beam-Shaping Using Phase-Only Adjustments.

    SciTech Connect

    Doerry, Armin W.

    2015-07-01

    Conventional beam-shaping for array antennas is accomplished via an amplitude-taper on the elemental radiators. It is well known that proper manipulation of the elemental phases can also shape the antenna far-field pattern. A fairly simple transformation from a desired amplitude-taper to a phase-taper can yield nearly equivalent results.

  7. Grounded Coplanar Waveguide Feeds Phased-Array Antenna

    NASA Technical Reports Server (NTRS)

    Ponchak, G.E.; Lee, R. Q.; Simons, R. N.; Fernandez, N.S.

    1993-01-01

    Prototype electronically steerable K-band end-fire antenna includes phased array of four printed-circuit linear dipole elements fed by grounded coplanar waveguide (GCPW). Distribution-and-phasing network of antenna fed through single entering antenna split equally by three GCPW T junctions onto four GCPW transmission lines.

  8. Fabrication and performance of a miniaturized 64-element high-frequency endoscopic phased array.

    PubMed

    Bezanson, Andre; Adamson, Rob; Brown, Jeremy

    2014-01-01

    We have developed a 40-MHz, 64-element phased-array transducer packaged in a 2.5 x 3.1 mm endoscopic form factor. The array is a forward-looking semi-kerfed design based on a 0.68Pb(Mg(1/3)Nb(2/3))O(3) - 0.32PbTiO3 (PMN-32%PT) single-crystal wafer with an element-to-element pitch of 38 µm. To achieve a miniaturized form factor, a novel technique of wire bonding the array elements to a polyimide flexible circuit board oriented parallel to the forward looking ultrasound beam and perpendicular to the array was developed. A technique of partially dicing into the back of the array was also implemented to improve the directivity of the array elements. The array was fabricated with a single-layer P(VDF-TrFE)-copolymer matching layer and a polymethylpentene (TPX) lens for passive elevation focusing to a depth of 7 mm. The two-way -6-dB pulse bandwidth was measured to be 55% and the average electromechanical coupling (k(eff)) for the individual elements was measured to be 0.62. The one-way -6-dB directivities from several array elements were measured to be ±20°, which was shown to be an improvement over an identical kerfless array. The -3-dB elevation focus resulting from the TPX lens was measured to be 152 µm at the focal depth, and the focused lateral resolution was measured to be 80 µm at a steering angle of 0°. To generate beam profiles and images, the probe was connected to a commercial ultrasound imaging platform which was reprogrammed to allow for phased array transmit beamforming and receive data collection. The collected RF data were then processed offline using a numerical computing script to generate sector images. The radiation pattern for the beamformed transmit pulse was collected along with images of wire phantoms in water and tissue-equivalent medium with a dynamic range of 60 dB. Finally, ex vivo tissue images were generated of porcine brain tissue. PMID:24402894

  9. Ultrasonic Phased-Array Characterization for NDE Applications

    NASA Technical Reports Server (NTRS)

    Hanley, John J.; Tennis, Richard F.; Pickens, Keith S.

    1995-01-01

    Southwest Research Institute (SwRI) recently fabricated and delivered the 100-channel Ultrasonic Phased-Array Testbed System (UPATS) for NASA's Langley Research Center. NASA prepared the specifications and provided the funding to develop UPATS in order to provide a tool for the improvement of ultrasonic nondestructive evaluation (NDE) and characterization of materials. UPATS incorporates state-of-the-art phased-array concepts such as beam steering, focusing, apodization, and phase-sensitive detection which make it possible to develop more sophisticated testing methodologies. It also can be used to investigate fundamental ultrasonic propagation and detection phenomena such as refraction, diffraction, scattering, and beam broadening.

  10. High-power phase locking of a fiber amplifier array

    NASA Astrophysics Data System (ADS)

    Shay, T. M.; Baker, J. T.; Sanchez, A. D.; Robin, C. A.; Vergien, C. L.; Zeringue, C.; Gallant, D.; Lu, Chunte A.; Pulford, Benjamin; Bronder, T. J.; Lucero, Arthur

    2009-02-01

    We report high power phase locked fiber amplifier array using the Self-Synchronous Locking of Optical Coherence by Single-detector Electronic-frequency Tagging technique. We report the first experimental results for a five element amplifier array with a total locked power of more than 725-W. We will report on experimental measurements of the phase fluctuations versus time when the control loop is closed. The rms phase error was measured to be λ/60. Recent results will be reported. To the best of the authors' knowledge this is the highest fiber laser power to be coherently combined.

  11. Phased Array Radiometer Calibration Using a Radiated Noise Source

    NASA Technical Reports Server (NTRS)

    Srinivasan, Karthik; Limaye, Ashutoch S.; Laymon, Charles A.; Meyer, Paul J.

    2010-01-01

    Electronic beam steering capability of phased array antenna systems offer significant advantages when used in real aperture imaging radiometers. The sensitivity of such systems is limited by the ability to accurately calibrate variations in the antenna circuit characteristics. Passive antenna systems, which require mechanical rotation to scan the beam, have stable characteristics and the noise figure of the antenna can be characterized with knowledge of its physical temperature [1],[2]. Phased array antenna systems provide the ability to electronically steer the beam in any desired direction. Such antennas make use of active components (amplifiers, phase shifters) to provide electronic scanning capability while maintaining a low antenna noise figure. The gain fluctuations in the active components can be significant, resulting in substantial calibration difficulties [3]. In this paper, we introduce two novel calibration techniques that provide an end-to-end calibration of a real-aperture, phased array radiometer system. Empirical data will be shown to illustrate the performance of both methods.

  12. A design concept for an MMIC microstrip phased array

    NASA Technical Reports Server (NTRS)

    Lee, R. Q.; Smetana, J.; Acosta, R.

    1986-01-01

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka band advanced satellite communication antenna systems. The proposed design concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required. The proposed design concept takes into consideration the RF characteristics and actual phyical dimensions of the MMIC devices. Also, solutions to spatial constraints and interconnections associated with currently available packaging designs are discussed. Finally, the design of the microstrip radiating elements and their radiation characteristics are examined.

  13. High performance relaxor-based ferroelectric single crystals for ultrasonic transducer applications.

    PubMed

    Chen, Yan; Lam, Kwok-Ho; Zhou, Dan; Yue, Qingwen; Yu, Yanxiong; Wu, Jinchuan; Qiu, Weibao; Sun, Lei; Zhang, Chao; Luo, Haosu; Chan, Helen L W; Dai, Jiyan

    2014-01-01

    Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) have drawn much attention in the ferroelectric field because of their excellent piezoelectric properties and high electromechanical coupling coefficients (d33~2000 pC/N, kt~60%) near the morphotropic phase boundary (MPB). Ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals also possess outstanding performance comparable with PMN-PT single crystals, but have higher phase transition temperatures (rhombohedral to tetragonal Trt, and tetragonal to cubic Tc) and larger coercive field Ec. Therefore, these relaxor-based single crystals have been extensively employed for ultrasonic transducer applications. In this paper, an overview of our work and perspectives on using PMN-PT and PIN-PMN-PT single crystals for ultrasonic transducer applications is presented. Various types of single-element ultrasonic transducers, including endoscopic transducers, intravascular transducers, high-frequency and high-temperature transducers fabricated using the PMN-PT and PIN-PMN-PT crystals and their 2-2 and 1-3 composites are reported. Besides, the fabrication and characterization of the array transducers, such as phased array, cylindrical shaped linear array, high-temperature linear array, radial endoscopic array, and annular array, are also addressed. PMID:25076222

  14. High Performance Relaxor-Based Ferroelectric Single Crystals for Ultrasonic Transducer Applications

    PubMed Central

    Chen, Yan; Lam, Kwok-Ho; Zhou, Dan; Yue, Qingwen; Yu, Yanxiong; Wu, Jinchuan; Qiu, Weibao; Sun, Lei; Zhang, Chao; Luo, Haosu; Chan, Helen L. W.; Dai, Jiyan

    2014-01-01

    Relaxor-based ferroelectric single crystals Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) have drawn much attention in the ferroelectric field because of their excellent piezoelectric properties and high electromechanical coupling coefficients (d33∼2000 pC/N, kt∼60%) near the morphotropic phase boundary (MPB). Ternary Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) single crystals also possess outstanding performance comparable with PMN-PT single crystals, but have higher phase transition temperatures (rhombohedral to tetragonal Trt, and tetragonal to cubic Tc) and larger coercive field Ec. Therefore, these relaxor-based single crystals have been extensively employed for ultrasonic transducer applications. In this paper, an overview of our work and perspectives on using PMN-PT and PIN-PMN-PT single crystals for ultrasonic transducer applications is presented. Various types of single-element ultrasonic transducers, including endoscopic transducers, intravascular transducers, high-frequency and high-temperature transducers fabricated using the PMN-PT and PIN-PMN-PT crystals and their 2-2 and 1-3 composites are reported. Besides, the fabrication and characterization of the array transducers, such as phased array, cylindrical shaped linear array, high-temperature linear array, radial endoscopic array, and annular array, are also addressed. PMID:25076222

  15. Code-modulated interferometric imaging system using phased arrays

    NASA Astrophysics Data System (ADS)

    Chauhan, Vikas; Greene, Kevin; Floyd, Brian

    2016-05-01

    Millimeter-wave (mm-wave) imaging provides compelling capabilities for security screening, navigation, and bio- medical applications. Traditional scanned or focal-plane mm-wave imagers are bulky and costly. In contrast, phased-array hardware developed for mass-market wireless communications and automotive radar promise to be extremely low cost. In this work, we present techniques which can allow low-cost phased-array receivers to be reconfigured or re-purposed as interferometric imagers, removing the need for custom hardware and thereby reducing cost. Since traditional phased arrays power combine incoming signals prior to digitization, orthogonal code-modulation is applied to each incoming signal using phase shifters within each front-end and two-bit codes. These code-modulated signals can then be combined and processed coherently through a shared hardware path. Once digitized, visibility functions can be recovered through squaring and code-demultiplexing operations. Pro- vided that codes are selected such that the product of two orthogonal codes is a third unique and orthogonal code, it is possible to demultiplex complex visibility functions directly. As such, the proposed system modulates incoming signals but demodulates desired correlations. In this work, we present the operation of the system, a validation of its operation using behavioral models of a traditional phased array, and a benchmarking of the code-modulated interferometer against traditional interferometer and focal-plane arrays.

  16. Performance limits of planar phased array with dome lens

    NASA Astrophysics Data System (ADS)

    Geren, W. P.; Taylor, Michael

    1998-10-01

    Communication systems based on low-earth-orbit (LEO) satellites have generated a requirement for high-performance phased array antennas with exceptional gain, sidelobe levels, and axial ratio over broad scan angles and 360 degree azimuth coverage. One approach to mitigating the effects of scan dependence is to cover the planar array with a hemispherical lens, or dome, which implements passive or active phase correction of the scanned beam. The phase correction over the dome surface may be represented as the function (Delta) (Phi) ((theta) , (phi) ), with (theta) and (phi) the polar and azimuth angles in a coordinate system having z-axis normal to the array. The purpose of this study was to determine the performance improvement achievable with such an ideal lens. Three cases were considered: a conventional lens with fixed optimum phase correction, an active lens with scan-dependent phase correction a function of polar angle only, and an active lens with phase correction a function of polar and azimuthal angles. In all cases, the planar array distribution had a fixed radial Taylor amplitude distribution and a phase taper consisting of a linear beam-pointing term and a non-linear focusing term.

  17. Separate-contact phase-locked semiconductor laser arrays

    NASA Technical Reports Server (NTRS)

    Katz, J.; Kapon, E.; Lindsey, C.; Margalit, S.; Yariv, A.

    1985-01-01

    The novel optoelectronic devices discussed, phase-locked semiconductor laser arrays with separate contacts can perform a variety of near field and far field pattern tailoring functions and control mutual coherence among array elements, as well as lasing wavelength selectivity and tunability. Attention is presently given to experimental results from such arrays, which indicate that the threshold currents of the 4-micron wide lasers employed are typically 60 mA. The separate contacts to each one of them are provided by means of two-level metallization.

  18. Optoelectronic Infrastructure for Radio Frequency and Optical Phased Arrays

    NASA Technical Reports Server (NTRS)

    Cai, Jianhong

    2015-01-01

    Optoelectronic integrated circuits offer radiation-hardened solutions for satellite systems in addition to improved size, weight, power, and bandwidth characteristics. ODIS, Inc., has developed optoelectronic integrated circuit technology for sensing and data transfer in phased arrays. The technology applies integrated components (lasers, amplifiers, modulators, detectors, and optical waveguide switches) to a radio frequency (RF) array with true time delay for beamsteering. Optical beamsteering is achieved by controlling the current in a two-dimensional (2D) array. In this project, ODIS integrated key components to produce common RF-optical aperture operation.

  19. Optical beam forming techniques for phased array antennas

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao; Chandler, C.

    1993-01-01

    Conventional phased array antennas using waveguide or coax for signal distribution are impractical for large scale implementation on satellites or spacecraft because they exhibit prohibitively large system size, heavy weight, high attenuation loss, limited bandwidth, sensitivity to electromagnetic interference (EMI) temperature drifts and phase instability. However, optical beam forming systems are smaller, lighter, and more flexible. Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are (1) the optical fiber replacement of conventional RF phased array distribution and control components, (2) spatial beam forming, and (3) optical beam splitting with integrated quasi-optical components. The optical fiber replacement and the spatial beam forming approaches were pursued by many organizations. Two new optical beam forming architectures are presented. Both architectures involve monolithic integration of the antenna radiating elements with quasi-optical grid detector arrays. The advantages of the grid detector array in the optical process are the higher power handling capability and the dynamic range. One architecture involves a modified version of the original spatial beam forming approach. The basic difference is the spatial light modulator (SLM) device for controlling the aperture field distribution. The original liquid crystal light valve SLM is replaced by an optical shuffling SLM, which was demonstrated for the 'smart pixel' technology. The advantages are the capability of generating the agile beams of a phased array antenna and to provide simultaneous transmit and receive functions. The second architecture considered is the optical beam splitting approach. This architecture involves an alternative amplitude control for each antenna element with an optical beam power divider comprised of mirrors and beam splitters. It also implements the quasi-optical grid phase shifter for phase control and grid

  20. Investigation into the effects of modification of the passive phase for improved manufacture of 1-3 connectivity piezocomposite transducers.

    PubMed

    O'Leary, R L; Hayward, G

    1999-01-01

    The 1-3 connectivity composite transducers comprise active piezoceramic pillars within a passive polymer matrix. The first stage in manufacturing the 1-3 material is to produce a bristle block (comprising a solid stock of active material with protruding pillars) by injection moulding or by dicing a piece of ceramic using precision sawing equipment. The bristle block is filled with a reactive polymer liquid that produces the passive polymer phase, and the filled block is machined to the desired dimensions. For optimum performance, the polymer phase should have complementary interaction with the ceramic phase as well as imparting dimensional stability. Epoxy-based polymers are the most usual passive materials because of their low viscosity in the uncured state and solvent resistance, coupled with their excellent adhesive, mechanical, and electrical properties. However, the curing of epoxy resins results in shrinkage of the polymer matrix and internal stress within the passive phase. This can lead to prestressing of the active ceramic material, distortion of pillars, reduction in the parallelism between the sides of pillars, acid, in certain circumstances, warpage of transducers. This is particularly evident when the solid stock in the bristle block is relatively thin. This paper reports the in situ modification of epoxy in the bristle block by UV-based low temperature polymerization of acrylate monomers within the epoxy matrix prior to polymerization of the epoxy resin. Internal stress measurements are presented to quantify the influence of this modification via a reduction of internal stress within the polymer matrix. Results from finite element analysis emphasise the conclusions of the experimental work, and examples of manufactured devices are presented. Composite transducer performance is assessed by laser measurement of surface displacement profiles, and a 50% improvement in surface displacement magnitude was observed for the modified devices. PMID:18238451

  1. Focusing of high-intensity ultrasound through the rib cage using a therapeutic random phased array.

    PubMed

    Bobkova, Svetlana; Gavrilov, Leonid; Khokhlova, Vera; Shaw, Adam; Hand, Jeffrey

    2010-06-01

    A method for focusing high-intensity ultrasound (HIFU) through a rib cage that aims to minimize heating of the ribs while maintaining high intensities at the focus (or foci) was proposed and tested theoretically and experimentally. Two approaches, one based on geometric acoustics and the other accounting for diffraction effects associated with propagation through the rib cage, were investigated theoretically for idealized source conditions. It is shown that for an idealized radiator, the diffraction approach provides a 23% gain in peak intensity and results in significantly less power losses on the ribs (1% vs. 7.5% of the irradiated power) compared with the geometric one. A 2-D 1-MHz phased array with 254 randomly distributed elements, tissue-mimicking phantoms and samples of porcine rib cages are used in experiments; the geometric approach is used to configure how the array is driven. Intensity distributions are measured in the plane of the ribs and in the focal plane using an infrared camera. Theoretical and experimental results show that it is possible to provide adequate focusing through the ribs without overheating them for a single focus and several foci, including steering at +/- 10-15 mm off and +/- 20 mm along the array axis. Focus splitting caused by the periodic spatial structure of ribs is demonstrated both in simulations and experiments; the parameters of splitting are quantified. The ability to produce thermal lesions with a split focal pattern in ex vivo porcine tissue placed beyond the rib phantom is also demonstrated. The results suggest that the method is potentially useful for clinical applications of HIFU, for which the rib cage lies between the transducer(s) and the targeted tissue. PMID:20510186

  2. Focusing of high intensity ultrasound through the rib cage using a therapeutic random phased array

    PubMed Central

    Bobkova, Svetlana; Gavrilov, Leonid; Khokhlova, Vera; Shaw, Adam; Hand, Jeffrey; #, ||

    2010-01-01

    A method for focusing high intensity ultrasound through a rib cage that aims to minimize heating of the ribs whilst maintaining high intensities at the focus (or foci) is proposed and tested theoretically and experimentally. Two approaches, one based on geometric acoustics and the other accounting for diffraction effects associated with propagation through the rib cage, are investigated theoretically for idealized source conditions. It is shown that for an idealized radiator the diffraction approach provides a 23% gain in peak intensity and results in significantly less power losses on the ribs (1% versus 7.5% of the irradiated power) compared with the geometric one. A 2D 1-MHz phased array with 254 randomly distributed elements, tissue mimicking phantoms, and samples of porcine rib cages are used in experiments; the geometric approach is used to configure how the array is driven. Intensity distributions are measured in the plane of the ribs and in the focal plane using an infra-red camera. Theoretical and experimental results show that it is possible to provide adequate focusing through the ribs without overheating them for a single focus and several foci, including steering at ± 10–15 mm off and ± 20 mm along the array axis. Focus splitting due to the periodic spatial structure of ribs is demonstrated both in simulations and experiments; the parameters of splitting are quantified. The ability to produce thermal lesions with a split focal pattern in ex vivo porcine tissue placed beyond the rib phantom is also demonstrated. The results suggest that the method is potentially useful for clinical applications of HIFU for which the rib cage lies between the transducer(s) and the targeted tissue. PMID:20510186

  3. Configuration of a Transverse Vibration Rod Type Ultrasonic Motor Using Three Longitudinal Transducers Driven in Three Different Vibration Phases

    NASA Astrophysics Data System (ADS)

    Suzuki, Atsuyuki; Kihara, Masaki; Katsumata, Yasuhiro; Kikuchi, Naoki; Tsujino, Jiromaru

    2004-05-01

    The vibration and load characteristics of an ultrasonic motor using a circular vibration disk with three longitudinal transducers have been studied. Three bolt-clamped Langevin type piezoelectric ceramic (PZT) longitudinal transducers (BLT) 20 mm in diameter were installed along the circumference of the circular disk, and complex transverse vibration rods were installed normally in the center of the circular disk. A complex transverse vibration rods are driven simultaneously using three power amplifiers with a phase difference of 120°. The transducers could also be driven using only one power amplifier in the case where the resonance frequencies were slightly different. A rotor disk installed on the free edge of the transverse vibration rod was pressed statically to a driving surface using a system for inducing static pressure. A maximum torque over 0.12 Nm was obtained using three power amplifiers under a static pressure of 1.7 MPa. A maximum rotation of 280 rpm and an efficiency of 1.13% were obtained using one power amplifier under a static pressure of 1.4 MPa.

  4. A vibration energy harvester using five-phase laminate composite transducer based on nanocrystalline soft magnetic alloy

    NASA Astrophysics Data System (ADS)

    Qiu, Jing; Wen, Yumei; Li, Ping; Chen, Hengjia; Yang, Jin

    2015-05-01

    In this research, a vibration energy harvester employing the FeCuNbSiB/Terfenol-D/PZT/Terfenol-D/FeCuNbSiB five-phase laminate composite transducer to convert mechanical vibration energy into electrical energy was presented. The electric output performance of the proposed vibration energy harvester has been investigated. It was found that appropriate FeCuNbSiB layer thickness was propitious to the electric output characteristics. Compared to traditional vibration energy harvester using Terfenol-D/PZT/Terfenol-D (MPM) transducer, the experimental results show that the proposed vibration energy harvester provides a remarkably enhanced output power performance. When the thickness of FeCuNbSiB layer was 30 μm, the optimum output power of vibration energy harvester achieved 4.00 mW/g for an acceleration of 0.8 g at frequency of 34.5 Hz, which was 1.29 times as great as that of traditional MPM transducer. Remarkably, this power is a very encouraging power figure and the proposed vibration energy harvester has great potential as far as its application in wireless sensor network.

  5. Experimental validation of an 8 element EMAT phased array probe for longitudinal wave generation

    NASA Astrophysics Data System (ADS)

    Le Bourdais, Florian; Marchand, Benoit

    2015-03-01

    Sodium cooled Fast Reactors (SFR) use liquid sodium as a coolant. Liquid sodium being opaque, optical techniques cannot be applied to reactor vessel inspection. This makes it necessary to develop alternative ways of assessing the state of the structures immersed in the medium. Ultrasonic pressure waves are well suited for inspection tasks in this environment, especially using pulsed electromagnetic acoustic transducers (EMAT) that generate the ultrasound directly in the liquid sodium. The work carried out at CEA LIST is aimed at developing phased array EMAT probes conditioned for reactor use. The present work focuses on the experimental validation of a newly manufactured 8 element probe which was designed for beam forming imaging in a liquid sodium environment. A parametric study is carried out to determine the optimal setup of the magnetic assembly used in this probe. First laboratory tests on an aluminium block show that the probe has the required beam steering capabilities.

  6. Experimental validation of an 8 element EMAT phased array probe for longitudinal wave generation

    SciTech Connect

    Le Bourdais, Florian Marchand, Benoit

    2015-03-31

    Sodium cooled Fast Reactors (SFR) use liquid sodium as a coolant. Liquid sodium being opaque, optical techniques cannot be applied to reactor vessel inspection. This makes it necessary to develop alternative ways of assessing the state of the structures immersed in the medium. Ultrasonic pressure waves are well suited for inspection tasks in this environment, especially using pulsed electromagnetic acoustic transducers (EMAT) that generate the ultrasound directly in the liquid sodium. The work carried out at CEA LIST is aimed at developing phased array EMAT probes conditioned for reactor use. The present work focuses on the experimental validation of a newly manufactured 8 element probe which was designed for beam forming imaging in a liquid sodium environment. A parametric study is carried out to determine the optimal setup of the magnetic assembly used in this probe. First laboratory tests on an aluminium block show that the probe has the required beam steering capabilities.

  7. Three-dimensional mid-air acoustic manipulation by ultrasonic phased arrays.

    PubMed

    Ochiai, Yoichi; Hoshi, Takayuki; Rekimoto, Jun

    2014-01-01

    The essence of levitation technology is the countervailing of gravity. It is known that an ultrasound standing wave is capable of suspending small particles at its sound pressure nodes. The acoustic axis of the ultrasound beam in conventional studies was parallel to the gravitational force, and the levitated objects were manipulated along the fixed axis (i.e. one-dimensionally) by controlling the phases or frequencies of bolted Langevin-type transducers. In the present study, we considered extended acoustic manipulation whereby millimetre-sized particles were levitated and moved three-dimensionally by localised ultrasonic standing waves, which were generated by ultrasonic phased arrays. Our manipulation system has two original features. One is the direction of the ultrasound beam, which is arbitrary because the force acting toward its centre is also utilised. The other is the manipulation principle by which a localised standing wave is generated at an arbitrary position and moved three-dimensionally by opposed and ultrasonic phased arrays. We experimentally confirmed that expanded-polystyrene particles of 0.6 mm, 1 mm, and 2 mm in diameter could be manipulated by our proposed method. PMID:24849371

  8. Three-Dimensional Mid-Air Acoustic Manipulation by Ultrasonic Phased Arrays

    PubMed Central

    Ochiai, Yoichi; Hoshi, Takayuki; Rekimoto, Jun

    2014-01-01

    The essence of levitation technology is the countervailing of gravity. It is known that an ultrasound standing wave is capable of suspending small particles at its sound pressure nodes. The acoustic axis of the ultrasound beam in conventional studies was parallel to the gravitational force, and the levitated objects were manipulated along the fixed axis (i.e. one-dimensionally) by controlling the phases or frequencies of bolted Langevin-type transducers. In the present study, we considered extended acoustic manipulation whereby millimetre-sized particles were levitated and moved three-dimensionally by localised ultrasonic standing waves, which were generated by ultrasonic phased arrays. Our manipulation system has two original features. One is the direction of the ultrasound beam, which is arbitrary because the force acting toward its centre is also utilised. The other is the manipulation principle by which a localised standing wave is generated at an arbitrary position and moved three-dimensionally by opposed and ultrasonic phased arrays. We experimentally confirmed that expanded-polystyrene particles of 0.6 mm, 1 mm, and 2 mm in diameter could be manipulated by our proposed method. PMID:24849371

  9. A Simplified Theory of Coupled Oscillator Array Phase Control

    NASA Technical Reports Server (NTRS)

    Pogorzelski, R. J.; York, R. A.

    1997-01-01

    Linear and planar arrays of coupled oscillators have been proposed as means of achieving high power rf sources through coherent spatial power combining. In such - applications, a uniform phase distribution over the aperture is desired. However, it has been shown that by detuning some of the oscillators away from the oscillation frequency of the ensemble of oscillators, one may achieve other useful aperture phase distributions. Notable among these are linear phase distributions resulting in steering of the output rf beam away from the broadside direction. The theory describing the operation of such arrays of coupled oscillators is quite complicated since the phenomena involved are inherently nonlinear. This has made it difficult to develop an intuitive understanding of the impact of oscillator tuning on phase control and has thus impeded practical application. In this work a simpl!fied theory is developed which facilitates intuitive understanding by establishing an analog of the phase control problem in terms of electrostatics.

  10. Adaptive array technique for differential-phase reflectometry in QUEST

    SciTech Connect

    Idei, H. Hanada, K.; Zushi, H.; Nagata, K.; Mishra, K.; Itado, T.; Akimoto, R.; Yamamoto, M. K.

    2014-11-15

    A Phased Array Antenna (PAA) was considered as launching and receiving antennae in reflectometry to attain good directivity in its applied microwave range. A well-focused beam was obtained in a launching antenna application, and differential-phase evolution was properly measured by using a metal reflector plate in the proof-of-principle experiment at low power test facilities. Differential-phase evolution was also evaluated by using the PAA in the Q-shu University Experiment with Steady State Spherical Tokamak (QUEST). A beam-forming technique was applied in receiving phased-array antenna measurements. In the QUEST device that should be considered as a large oversized cavity, standing wave effect was significantly observed with perturbed phase evolution. A new approach using derivative of measured field on propagating wavenumber was proposed to eliminate the standing wave effect.

  11. Adaptive array technique for differential-phase reflectometry in QUEST.

    PubMed

    Idei, H; Nagata, K; Mishra, K; Yamamoto, M K; Itado, T; Akimoto, R; Hanada, K; Zushi, H

    2014-11-01

    A Phased Array Antenna (PAA) was considered as launching and receiving antennae in reflectometry to attain good directivity in its applied microwave range. A well-focused beam was obtained in a launching antenna application, and differential-phase evolution was properly measured by using a metal reflector plate in the proof-of-principle experiment at low power test facilities. Differential-phase evolution was also evaluated by using the PAA in the Q-shu University Experiment with Steady State Spherical Tokamak (QUEST). A beam-forming technique was applied in receiving phased-array antenna measurements. In the QUEST device that should be considered as a large oversized cavity, standing wave effect was significantly observed with perturbed phase evolution. A new approach using derivative of measured field on propagating wavenumber was proposed to eliminate the standing wave effect. PMID:25430255

  12. Adaptive array technique for differential-phase reflectometry in QUESTa)

    NASA Astrophysics Data System (ADS)

    Idei, H.; Nagata, K.; Mishra, K.; Yamamoto, M. K.; Itado, T.; Akimoto, R.; Hanada, K.; Zushi, H.

    2014-11-01

    A Phased Array Antenna (PAA) was considered as launching and receiving antennae in reflectometry to attain good directivity in its applied microwave range. A well-focused beam was obtained in a launching antenna application, and differential-phase evolution was properly measured by using a metal reflector plate in the proof-of-principle experiment at low power test facilities. Differential-phase evolution was also evaluated by using the PAA in the Q-shu University Experiment with Steady State Spherical Tokamak (QUEST). A beam-forming technique was applied in receiving phased-array antenna measurements. In the QUEST device that should be considered as a large oversized cavity, standing wave effect was significantly observed with perturbed phase evolution. A new approach using derivative of measured field on propagating wavenumber was proposed to eliminate the standing wave effect.

  13. Phase-locked laser array through global antenna mutual coupling

    DOE PAGESBeta

    Kao, Tsung -Yu; Reno, John L.; Hu, Qing

    2016-01-01

    Here, phase locking of an array of lasers is a highly effective way in beam shaping, to increase the output power, and to reduce lasing threshold. In this work, we present a novel phase-locking mechanism based on "antenna mutual coupling" wherein laser elements interact through far-field radiations with definite phase relations. This allows long-range global coupling among array elements to achieve robust 2-dimensional phase-locked laser array. The new scheme is ideal for lasers with deep sub-wavelength confined cavity such as nanolasers, where the divergent beam pattern could be used to form strong coupling among elements in the array. We experimentallymore » demonstrated such a scheme using sub-wavelength short-cavity surface-emitting lasers at terahertz frequency. More than 37 laser elements are phase-locked to each other, delivering up to 6.5 mW single-mode radiations at ~3 terahertz, with maximum 450-mW/A slope efficiency and near diffraction limit beam divergence.« less

  14. Phase-locked laser arrays through global antenna mutual coupling

    NASA Astrophysics Data System (ADS)

    Kao, Tsung-Yu; Reno, John L.; Hu, Qing

    2016-08-01

    Phase locking of an array of lasers is a highly effective method in beam shaping because it increases the output power and reduces the lasing threshold. Here, we show a conceptually novel phase-locking mechanism based on ‘antenna mutual coupling’ in which laser elements interact through far-field radiations with definite phase relations. This allows a long-range global coupling among the array elements to achieve a robust phase locking in two-dimensional laser arrays. The scheme is ideal for lasers with a deep subwavelength confined cavity, such as nanolasers, whose divergent beam patterns could be used to achieve a strong coupling among the elements in the array. We demonstrated experimentally such a scheme based on subwavelength short-cavity surface-emitting lasers at terahertz frequencies. More than 37 laser elements that span over ∼8 λo were phase locked to each other, and delivered up to 6.5 mW (in a pulsed operation) single-mode radiation at ∼3 THz, with a maximum 450 mW A–1 slope efficiency and a near-diffraction-limited beam divergence.

  15. Phased-array sources based on nonlinear metamaterial nanocavities

    DOE PAGESBeta

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P.; Liu, Sheng; Luk, Ting S.; Kadlec, Emil Andrew; Shaner, Eric A.; Klem, John Frederick; Sinclair, Michael B.; et al

    2015-07-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization.more » As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (~5 μm): a beam splitter and a polarizing beam splitter. As a result, proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum.« less

  16. Phase-locked laser array through global antenna mutual coupling

    SciTech Connect

    Kao, Tsung -Yu; Reno, John L.; Hu, Qing

    2016-01-01

    Here, phase locking of an array of lasers is a highly effective way in beam shaping, to increase the output power, and to reduce lasing threshold. In this work, we present a novel phase-locking mechanism based on "antenna mutual coupling" wherein laser elements interact through far-field radiations with definite phase relations. This allows long-range global coupling among array elements to achieve robust 2-dimensional phase-locked laser array. The new scheme is ideal for lasers with deep sub-wavelength confined cavity such as nanolasers, where the divergent beam pattern could be used to form strong coupling among elements in the array. We experimentally demonstrated such a scheme using sub-wavelength short-cavity surface-emitting lasers at terahertz frequency. More than 37 laser elements are phase-locked to each other, delivering up to 6.5 mW single-mode radiations at ~3 terahertz, with maximum 450-mW/A slope efficiency and near diffraction limit beam divergence.

  17. Phased-array sources based on nonlinear metamaterial nanocavities

    PubMed Central

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P.; Liu, Sheng; Luk, Ting S.; Kadlec, Emil A.; Shaner, Eric A.; Klem, John F.; Sinclair, Michael B.; Brener, Igal

    2015-01-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (∼5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum. PMID:26126879

  18. Phased-array sources based on nonlinear metamaterial nanocavities.

    PubMed

    Wolf, Omri; Campione, Salvatore; Benz, Alexander; Ravikumar, Arvind P; Liu, Sheng; Luk, Ting S; Kadlec, Emil A; Shaner, Eric A; Klem, John F; Sinclair, Michael B; Brener, Igal

    2015-01-01

    Coherent superposition of light from subwavelength sources is an attractive prospect for the manipulation of the direction, shape and polarization of optical beams. This phenomenon constitutes the basis of phased arrays, commonly used at microwave and radio frequencies. Here we propose a new concept for phased-array sources at infrared frequencies based on metamaterial nanocavities coupled to a highly nonlinear semiconductor heterostructure. Optical pumping of the nanocavity induces a localized, phase-locked, nonlinear resonant polarization that acts as a source feed for a higher-order resonance of the nanocavity. Varying the nanocavity design enables the production of beams with arbitrary shape and polarization. As an example, we demonstrate two second harmonic phased-array sources that perform two optical functions at the second harmonic wavelength (∼5 μm): a beam splitter and a polarizing beam splitter. Proper design of the nanocavity and nonlinear heterostructure will enable such phased arrays to span most of the infrared spectrum. PMID:26126879

  19. Scattering of the field of a multi-element phased array by human ribs

    NASA Astrophysics Data System (ADS)

    Gélat, P.; ter Haar, G.; Saffari, N.

    2012-03-01

    The efficacy of high intensity focused ultrasound (HIFU) for the non-invasive treatment of cancer has been demonstrated for a range of different cancers including those of the liver, kidney, prostate and breast. As a non-invasive focused therapy, HIFU offers considerable advantages over other techniques such as chemotherapy and surgical resection, in terms of invasiveness and risk of harmful side effects. Despite its advantages, however, there are a number of significant challenges currently hindering its widespread clinical application. One of these challenges is the need to transmit sufficient energy through the ribcage to induce tissue necrosis at the required foci whilst minimising the formation of side lobes. Multielement random arrays are currently showing great promise in overcoming the limitations of single-element transducers. Nevertheless, successfully treating a patient for liver tumours requires a thorough understanding of the way in which the ultrasonic pressure field from a HIFU array is scattered by the ribcage. A mesh of quadratic pressure patches was generated using CT scan data for ribs nine to twelve on the right side. A boundary element approach based on a Generalised Minimal Residual (GMRES) implementation of the Burton-Miller formulation was used, in conjunction with phase conjugation techniques to focus the field of a 256-element random HIFU array past the ribs at both intercostal and transcostal treatment locations. This method has the advantage of accounting for full effects of scattering and diffraction in three dimensions under continuous wave excitation.

  20. Phased array antenna analysis using hybrid finite element methods

    NASA Astrophysics Data System (ADS)

    McGrath, Daniel T.

    1993-06-01

    This research in computational electromagnetics developed a new method for predicting the near-field mutual coupling effects in phased array antennas, using the finite element method (FEM) in combination with integral equations. Accurate feed modeling is accomplished by enforcing continuity between the FEM solution and an arbitrary number of wave guide models across a ground plane aperture. A periodic integral equation is imposed above the antenna's physical structure in order to enforce the radiation condition and to confine the analysis to an array unit cell. The electric field is expanded in terms of vector finite elements, and Galerkin's method is used to write the problem as a matrix equation. A general-purpose computer code was developed and validated by comparing its results to published data for several array types. Its versatility was demonstrated with predictions of the scanning properties of arrays of printed dipoles and printed flared notches.

  1. Detection Performance of a Diffusive Wave Phased Array

    NASA Astrophysics Data System (ADS)

    Morgan, Stephen P.

    2004-04-01

    Diffusive wave phased arrays have been demonstrated to be a sensitive method of detecting inhomogeneities embedded in heavily scattering media. However, the increase in sensitivity is coupled with an increase in noise, so that the optimum performance may not be obtained when the sources are modulated in antiphase. The performance of a range of configurations in the presence of Gaussian noise is investigated by using probabilistic detection theory. A model of diffusive wave propagation through scattering media is used to demonstrate that the phase performance can be improved by controlling the relative phase difference between the two sources. However, the best performance is obtained by using the amplitude response of a single source system. The major benefit of a phased array system is therefore the rejection of common systematic noise.

  2. Removing Background Noise with Phased Array Signal Processing

    NASA Technical Reports Server (NTRS)

    Podboy, Gary; Stephens, David

    2015-01-01

    Preliminary results are presented from a test conducted to determine how well microphone phased array processing software could pull an acoustic signal out of background noise. The array consisted of 24 microphones in an aerodynamic fairing designed to be mounted in-flow. The processing was conducted using Functional Beam forming software developed by Optinav combined with cross spectral matrix subtraction. The test was conducted in the free-jet of the Nozzle Acoustic Test Rig at NASA GRC. The background noise was produced by the interaction of the free-jet flow with the solid surfaces in the flow. The acoustic signals were produced by acoustic drivers. The results show that the phased array processing was able to pull the acoustic signal out of the background noise provided the signal was no more than 20 dB below the background noise level measured using a conventional single microphone equipped with an aerodynamic forebody.

  3. MSAT-X phased array antenna adaptions to airborne applications

    NASA Technical Reports Server (NTRS)

    Sparks, C.; Chung, H. H.; Peng, S. Y.

    1988-01-01

    The Mobile Satellite Experiment (MSAT-X) phased array antenna is being modified to meet future requirements. The proposed system consists of two high gain antennas mounted on each side of a fuselage, and a low gain antenna mounted on top of the fuselage. Each antenna is an electronically steered phased array based on the design of the MSAT-X antenna. A beamforming network is connected to the array elements via coaxial cables. It is essential that the proposed antenna system be able to provide an adequate communication link over the required space coverage, which is 360 degrees in azimuth and from 20 degrees below the horizon to the zenith in elevation. Alternative design concepts are suggested. Both open loop and closed loop backup capabilities are discussed. Typical antenna performance data are also included.

  4. Flat HIFU transducer with a sawtooth-shaped ultrasound radiation face

    NASA Astrophysics Data System (ADS)

    Son, Keon-Ho; Cho, Young-Ki; Kim, Dae-Seung; Kim, Myung-Deok; Kang, Kook-Jin

    2013-10-01

    High-intensity focused ultrasound (HIFU) transducers are spherically-curved in order to obtain a high intensity gain of the converged ultrasound energy at the geometrical focus. Ultrasound imaging devices monitor the procedure of HIFU treatment in ultrasound-guided HIFU systems where the image probe is positioned at the apex of the HIFU transducer, which has a spherical surface. However, the remote image probe's location yields a poor image quality compared to that obtained using conventional ultrasound imaging where the image probe is in direct contact with the surface. A phased array HIFU transducer with a new structure is suggested to overcome this limitation. The centers of the array elements are distributed over the flat surface of the transducer. However, the elements are tilted to form a geometrical focus, like a transducer with a spherically-curved surface, to obtain a high focal gain. The cross-section of the ultrasound radiation face of the transducer resembles the teeth of a saw. The acoustic field emitted from this transducer was simulated in order to design and produce the transducer. The simulation was compared with the measured sound field to verify that the transducer was correctly manufactured and designed; subsequently, the acoustic power was measured, and ultrasound images were obtained through the installation of an image probe on the transducer, which confirmed the application of this transducer to HIFU treatment.

  5. NASA Adaptive Multibeam Phased Array (AMPA): An application study

    NASA Technical Reports Server (NTRS)

    Mittra, R.; Lee, S. W.; Gee, W.

    1982-01-01

    The proposed orbital geometry for the adaptive multibeam phased array (AMPA) communication system is reviewed and some of the system's capabilities and preliminary specifications are highlighted. Typical AMPA user link models and calculations are presented, the principal AMPA features are described, and the implementation of the system is demonstrated. System tradeoffs and requirements are discussed. Recommendations are included.

  6. Looking Below the Surface with Ultrasonic Phased Array

    SciTech Connect

    Cinson, Anthony D.; Crawford, Susan L.

    2010-10-01

    This article is a brief tutorial on the benefits of volumetric ultrasonic phased array line scanning. The article describes the need, the approach, and the methods/practices used to analyze the data for flaw detection and characterization in the nuclear power plant component arena.

  7. Transducer characterization

    SciTech Connect

    Cross, B. T.; Eoff, J. M.; Schuetz, L. J.; Cunningham, K. R.

    1980-07-02

    This report has been prepared specifically for ultrasonic transducer users within the Nondestructive Testing Evaluation (NDE) community of the weapons complex. The purpose of the report is to establish an initial set of uniform procedures for measuring and recording transducer performance data, and to establish a common foundation on which more comprehensive transducer performance evaluations may be added as future transducer performance criteria expands. Transducer parameters and the problems with measuring them are discussed and procedures for measuring transducer performance are recommended with special precautionary notes regarding critical aspects of each measurement. An important consideration regarding the recommended procedures is the cost of implementation. There are two distinct needs for transducer performance characterization in the complex. Production oriented users need a quick, reliable means to check a transducer to ascertain its suitability for continued service. Development groups and the Transducer Center need a comprehensive characterization means to collect adequate data to evaluate theoretical concepts or to build exact replacement transducers. The instrumentation, equipment, and procedures recommended for monitoring production transducers are utilitarian and provide only that information needed to determine transducer condition.

  8. Feasibility of vibro-acoustography with a quasi-2D ultrasound array transducer for detection and localizing of permanent prostate brachytherapy seeds: A pilot ex vivo study

    SciTech Connect

    Mehrmohammadi, Mohammad; Kinnick, Randall R.; Fatemi, Mostafa; Alizad, Azra; Davis, Brian J.

    2014-09-15

    Purpose: Effective permanent prostate brachytherapy (PPB) requires precise placement of radioactive seeds in and around the prostate. The impetus for this research is to examine a new ultrasound-based imaging modality, vibro-acoustography (VA), which may serve to provide a high rate of PPB seed detection while also effecting enhanced prostate imaging. The authors investigate the ability of VA, implemented on a clinical ultrasound (US) scanner and equipped with a quasi-2D (Q2D) array US transducer, to detect and localize PPB seeds in excised prostate specimens. Methods: Nonradioactive brachytherapy seeds were implanted into four excised cadaver prostates. A clinical US scanner equipped with a Q2D array US transducer was customized to acquire both US and C-scan VA images at various depths. The VA images were then used to detect and localize the implanted seeds in prostate tissue. To validate the VA results, computed tomography (CT) images of the same tissue samples were obtained to serve as the reference by which to evaluate the performance of VA in PPB seed detection. Results: The results indicate that VA is capable of accurately identifying the presence and distribution of PPB seeds with a high imaging contrast. Moreover, a large ratio of the PPB seeds implanted into prostate tissue samples could be detected through acquired VA images. Using CT-based seed identification as the standard, VA was capable of detecting 74%–92% of the implanted seeds. Additionally, the angular independency of VA in detecting PPB seeds was demonstrated through a well-controlled phantom experiment. Conclusions: Q2DVA detected a substantial portion of the seeds by using a 2D array US transducer in excised prostate tissue specimens. While VA has inherent advantages associated with conventional US imaging, it has the additional advantage of permitting detection of PPB seeds independent of their orientation. These results suggest the potential of VA as a method for PPB imaging that

  9. Feasibility of vibro-acoustography with a quasi-2D ultrasound array transducer for detection and localizing of permanent prostate brachytherapy seeds: A pilot ex vivo study

    PubMed Central

    Mehrmohammadi, Mohammad; Alizad, Azra; Kinnick, Randall R.; Davis, Brian J.; Fatemi, Mostafa

    2014-01-01

    Purpose: Effective permanent prostate brachytherapy (PPB) requires precise placement of radioactive seeds in and around the prostate. The impetus for this research is to examine a new ultrasound-based imaging modality, vibro-acoustography (VA), which may serve to provide a high rate of PPB seed detection while also effecting enhanced prostate imaging. The authors investigate the ability of VA, implemented on a clinical ultrasound (US) scanner and equipped with a quasi-2D (Q2D) array US transducer, to detect and localize PPB seeds in excised prostate specimens. Methods: Nonradioactive brachytherapy seeds were implanted into four excised cadaver prostates. A clinical US scanner equipped with a Q2D array US transducer was customized to acquire both US and C-scan VA images at various depths. The VA images were then used to detect and localize the implanted seeds in prostate tissue. To validate the VA results, computed tomography (CT) images of the same tissue samples were obtained to serve as the reference by which to evaluate the performance of VA in PPB seed detection. Results: The results indicate that VA is capable of accurately identifying the presence and distribution of PPB seeds with a high imaging contrast. Moreover, a large ratio of the PPB seeds implanted into prostate tissue samples could be detected through acquired VA images. Using CT-based seed identification as the standard, VA was capable of detecting 74%–92% of the implanted seeds. Additionally, the angular independency of VA in detecting PPB seeds was demonstrated through a well-controlled phantom experiment. Conclusions: Q2DVA detected a substantial portion of the seeds by using a 2D array US transducer in excised prostate tissue specimens. While VA has inherent advantages associated with conventional US imaging, it has the additional advantage of permitting detection of PPB seeds independent of their orientation. These results suggest the potential of VA as a method for PPB imaging that

  10. Development of a pseudo phased array technique using EMATs for DM weld testing

    SciTech Connect

    Cobb, Adam C. Fisher, Jay L.; Shiokawa, Nobuyuki; Hamano, Toshiaki; Horikoshi, Ryoichi; Ido, Nobukazu

    2015-03-31

    Ultrasonic inspection of dissimilar metal (DM) welds in piping with cast austenitic stainless steel (CASS) has been an area ongoing research for many years given its prevalence in the petrochemical and nuclear industries. A typical inspection strategy for pipe welds is to use an ultrasonic phased array system to scan the weld from a sensor located on the outer surface of the pipe. These inspection systems generally refract either longitudinal or shear vertical (SV) waves at varying angles to inspect the weld radially. In DM welds, however, the welding process can produce a columnar grain structure in the CASS material in a specific orientation. This columnar grain structure can skew ultrasonic waves away from their intended path, especially for SV and longitudinal wave modes. Studies have shown that inspection using the shear horizontal (SH) wave mode significantly reduces the effect of skewing. Electromagnetic acoustic transducers (EMATs) are known to be effective for producing SH waves in field settings. This paper presents an inspection strategy that seeks to reproduce the scanning and imaging capabilities of a commercial phase array system using EMATs. A custom-built EMAT was used to collect data at multiple propagation angles, and a processing strategy known as the synthetic aperture focusing technique (SAFT) was used to combine the data to produce an image. Results are shown using this pseudo phased array technique to inspect samples with a DM weld and artificial defects, demonstrating the potential of this approach in a laboratory setting. Recommendations for future work to transition the technique to the field are also provided.

  11. Development of a pseudo phased array technique using EMATs for DM weld testing

    NASA Astrophysics Data System (ADS)

    Cobb, Adam C.; Fisher, Jay L.; Shiokawa, Nobuyuki; Hamano, Toshiaki; Horikoshi, Ryoichi; Ido, Nobukazu

    2015-03-01

    Ultrasonic inspection of dissimilar metal (DM) welds in piping with cast austenitic stainless steel (CASS) has been an area ongoing research for many years given its prevalence in the petrochemical and nuclear industries. A typical inspection strategy for pipe welds is to use an ultrasonic phased array system to scan the weld from a sensor located on the outer surface of the pipe. These inspection systems generally refract either longitudinal or shear vertical (SV) waves at varying angles to inspect the weld radially. In DM welds, however, the welding process can produce a columnar grain structure in the CASS material in a specific orientation. This columnar grain structure can skew ultrasonic waves away from their intended path, especially for SV and longitudinal wave modes. Studies have shown that inspection using the shear horizontal (SH) wave mode significantly reduces the effect of skewing. Electromagnetic acoustic transducers (EMATs) are known to be effective for producing SH waves in field settings. This paper presents an inspection strategy that seeks to reproduce the scanning and imaging capabilities of a commercial phase array system using EMATs. A custom-built EMAT was used to collect data at multiple propagation angles, and a processing strategy known as the synthetic aperture focusing technique (SAFT) was used to combine the data to produce an image. Results are shown using this pseudo phased array technique to inspect samples with a DM weld and artificial defects, demonstrating the potential of this approach in a laboratory setting. Recommendations for future work to transition the technique to the field are also provided.

  12. Comparison of 3-D synthetic aperture phased-array ultrasound imaging and parallel beamforming.

    PubMed

    Rasmussen, Morten Fischer; Jensen, Jørgen Arendt

    2014-10-01

    This paper demonstrates that synthetic aperture imaging (SAI) can be used to achieve real-time 3-D ultrasound phased-array imaging. It investigates whether SAI increases the image quality compared with the parallel beamforming (PB) technique for real-time 3-D imaging. Data are obtained using both simulations and measurements with an ultrasound research scanner and a commercially available 3.5- MHz 1024-element 2-D transducer array. To limit the probe cable thickness, 256 active elements are used in transmit and receive for both techniques. The two imaging techniques were designed for cardiac imaging, which requires sequences designed for imaging down to 15 cm of depth and a frame rate of at least 20 Hz. The imaging quality of the two techniques is investigated through simulations as a function of depth and angle. SAI improved the full-width at half-maximum (FWHM) at low steering angles by 35%, and the 20-dB cystic resolution by up to 62%. The FWHM of the measured line spread function (LSF) at 80 mm depth showed a difference of 20% in favor of SAI. SAI reduced the cyst radius at 60 mm depth by 39% in measurements. SAI improved the contrast-to-noise ratio measured on anechoic cysts embedded in a tissue-mimicking material by 29% at 70 mm depth. The estimated penetration depth on the same tissue-mimicking phantom shows that SAI increased the penetration by 24% compared with PB. Neither SAI nor PB achieved the design goal of 15 cm penetration depth. This is likely due to the limited transducer surface area and a low SNR of the experimental scanner used. PMID:25265174

  13. Magnetic Properties of Liquid-Phase Sintered CoFe2O4 for Application in Magnetoelastic and Magnetoelectric Transducers

    PubMed Central

    de Brito, Vera Lúcia Othéro; Cunha, Stéphanie Alá; Lemos, Leonardo Violim; Nunes, Cristina Bormio

    2012-01-01

    Cobalt ferrite is a ferrimagnetic magnetostrictive ceramic that has potential application in magnetoelastic and magnetoelectric transducers. In this work, CoFe2O4 was obtained using a conventional ceramic method and Bi2O3 was used as additive in order to obtain liquid-phase sintered samples. Bi2O3 was added to the ferrite in amounts ranging from 0.25 mol% to 0.45 mol% and samples were sintered at 900 °C and 950 °C. It was observed the presence of Bi-containing particles in the microstructure of the sintered samples and the magnetostriction results indicated microstructural anisotropy. It was verified that it is possible to get dense cobalt ferrites, liquid-phase sintered, with relative densities higher than 90% and with magnetostriction values very close to samples sintered without additives. PMID:23112589

  14. A 220 GHz reflection-type phased array concept study

    NASA Astrophysics Data System (ADS)

    Hedden, Abigail S.; Dietlein, Charles R.; Wikner, David A.

    2011-05-01

    The goal of this project is to enable light-weight, durable, and portable systems capable of performing standoff detection of person-borne improvised explosive devices (PB-IEDs) through the development of millimeter-wave reflection-type phased arrays. Electronic beam steering eliminates the need for complex mechanical scanners that are commonly implemented with millimeter-wave imaging systems and would reduce overall system size and weight. We present a concept study of a 220 GHz reflection-type phased array for the purpose of performing beam scanning of a confocal reflector system. Requirements for effective imaging of the desired target region are established, including spatial resolution, total scan angle, and number of image pixels achievable. We examine the effects of array architecture on beam characteristics as it is scanned off broadside, including Gaussicity and encircled energy. Benchmark requirements are determined and compared with the capabilities of several potential phase shifter technologies, including MEMS-based variable capacitor phase shifters, switches, and varactor diode-based phase shifters.

  15. Binary-Phase Fourier Gratings for Nonuniform Array Generation

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Crow, Robert W.; Ashley, Paul R.

    2003-01-01

    We describe a design method for a binary-phase Fourier grating that generates an array of spots with nonuniform, user-defined intensities symmetric about the zeroth order. Like the Dammann fanout grating approach, the binary-phase Fourier grating uses only two phase levels in its grating surface profile to generate the final spot array. Unlike the Dammann fanout grating approach, this method allows for the generation of nonuniform, user-defined intensities within the final fanout pattern. Restrictions governing the specification and realization of the array's individual spot intensities are discussed. Design methods used to realize the grating employ both simulated annealing and nonlinear optimization approaches to locate optimal solutions to the grating design problem. The end-use application driving this development operates in the near- to mid-infrared spectrum - allowing for higher resolution in grating specification and fabrication with respect to wavelength than may be available in visible spectrum applications. Fabrication of a grating generating a user-defined nine spot pattern is accomplished in GaAs for the near-infrared. Characterization of the grating is provided through the measurement of individual spot intensities, array uniformity, and overall efficiency. Final measurements are compared to calculated values with a discussion of the results.

  16. Reverse Phase Protein Arrays: Mapping the path towards personalized medicine

    PubMed Central

    Gallagher, Rosa I.; Espina, Virginia

    2016-01-01

    Reverse phase protein array (RPPA) technology evolved from the advent of miniaturized immunoassays and gene microarray technology. Reverse phase protein arrays provide either a low throughput or high throughput methodology for quantifying proteins and their post-translationally modified forms in both cellular and non-cellular samples. As the demand for patient tailored therapies increases so does the need for precise and sensitive technology to accurately profile the molecular circuitry driving an individual patient’s disease. RPPAs are currently utilized in clinical trials for profiling and comparing the functional state of protein signaling pathways, either temporally within tumors, between patients, or within the same patients before/after treatment. RPPAs are generally employed for quantifying large numbers of samples on one array, under identical experimental conditions. However, the goal of personalized cancer medicine is to design therapies based on the molecular portrait of a patient’s tumor, which in turn result in more efficacious treatments with less toxicity. Therefore, RPPAs are also being validated for low throughput assays of individual patient samples. This review explores reverse phase protein array technology in the cancer research field, concentrating on its role as a fundamental tool for deciphering protein signaling networks and its emerging role in personalized medicine. PMID:25358623

  17. Scan blindness in infinite phased arrays of printed dipoles

    NASA Technical Reports Server (NTRS)

    Pozar, D. M.; Schaubert, D. H.

    1984-01-01

    A comprehensive study of infinite phased arrays of printed dipole antennas is presented, with emphasis on the scan blindness phenomenon. A rigorous and efficient moment method procedure is used to calculate the array impedance versus scan angle. Data are presented for the input reflection coefficient for various element spacings and substrate parameters. A simple theory, based on coupling from Floquet modes to surface wave modes on the substrate, is shown to predict the occurrence of scan blindness. Measurements from a waveguide simulator of a blindness condition confirm the theory.

  18. 2-D scalable optical controlled phased-array antenna system

    NASA Astrophysics Data System (ADS)

    Chen, Maggie Yihong; Howley, Brie; Wang, Xiaolong; Basile, Panoutsopoulos; Chen, Ray T.

    2006-02-01

    A novel optoelectronically-controlled wideband 2-D phased-array antenna system is demonstrated. The inclusion of WDM devices makes a highly scalable system structure. Only (M+N) delay lines are required to control a M×N array. The optical true-time delay lines are combination of polymer waveguides and optical switches, using a single polymeric platform and are monolithically integrated on a single substrate. The 16 time delays generated by the device are measured to range from 0 to 175 ps in 11.6 ps. Far-field patterns at different steering angles in X-band are measured.

  19. SAR processing with stepped chirps and phased array antennas.

    SciTech Connect

    Doerry, Armin Walter

    2006-09-01

    Wideband radar signals are problematic for phased array antennas. Wideband radar signals can be generated from series or groups of narrow-band signals centered at different frequencies. An equivalent wideband LFM chirp can be assembled from lesser-bandwidth chirp segments in the data processing. The chirp segments can be transmitted as separate narrow-band pulses, each with their own steering phase operation. This overcomes the problematic dilemma of steering wideband chirps with phase shifters alone, that is, without true time-delay elements.

  20. Acoustooptic pulse-echo transducer system

    NASA Technical Reports Server (NTRS)

    Claus, R. O.; Wade, J. C.

    1983-01-01

    A pulse-echo transducer system which uses an ultrasonic generating element and an optical detection technique is described. The transmitting transducer consists of a concentric ring electrode pattern deposited on a circular, X-cut quartz substrate with a circular hole in the center. The rings are independently pulsed with a sequence high voltage signals phased in such a way that the ultrasonic waves generated by the separate rings superimpose to produce a composite field which is focused at a controllable distance below the surface of the specimen. The amplitude of the field reflected from this focus position is determined by the local reflection coefficient of the medium at the effective focal point. By processing the signals received for a range of ultrasonic transducer array focal lengths, the system can be used to locate and size anomalies within solids and liquids. Applications in both nondestructive evaluation and biomedical scanning are suggested.

  1. Brazilian Decimetre Array (Phase-1): Initial solar observations

    NASA Astrophysics Data System (ADS)

    Ramesh, R.; Sawant, H. S.; Cecatto, J. R.; Faria, C.; Fernandes, F. C. R.; Kathiravan, C.; Suryanarayana, G. S.

    An East-West one-dimensional radio interferometer array consisting of 5 parabolic dish antennas has been set-up at Cachoeira Paulista, Brazil (Longitude: 45°0'20″W, Latitude: 22°41'19″S) for observations of Sun and some of the strong sidereal sources by the Instituto Nacional de Pesquisas Espaciais (INPE), Brazil. This is Phase-1 of the proposed Brazilian Decimetre Array (BDA) and can be operated at any frequency in the range 1.2-1.7 GHz. The instrument is functional since November 2004 onwards at 1.6 GHz. The angular and temporal resolution at the above frequency range are ˜3' and 100 ms, respectively. We present here the initial solar observations carried out with this array.

  2. Subharmonic phased array for crack evaluation using surface acoustic wave

    NASA Astrophysics Data System (ADS)

    Ouchi, Akihiro; Sugawara, Azusa; Ohara, Yoshikazu; Yamanaka, Kazushi

    2015-07-01

    To accurately measure closed crack length, we proposed an imaging method using a subharmonic phased array for crack evaluation using surface acoustic waves (SAW SPACE) with water immersion. We applied SAW SPACE to the hole specimen in a fundamental array (FA) image. The hole was imaged with high resolution. Subsequently, SAW SPACE was applied to fatigue crack and stress corrosion crack (SCC) specimens. A fatigue crack was imaged in FA and subharmonic array (SA) images, and the length of this particular fatigue crack measured in the images was almost the same as that measured by optical observation. The SCC was imaged and its length was accurately measured in the SA image, whereas it was underestimated in the FA image and by optical observation. Thus, we demonstrated that SAW SPACE with water immersion is useful for the accurate measurement of closed crack length and for imaging the distribution of open and closed parts of cracks with high resolution.

  3. Phased Arrays of Ground and Airborne Mobile Terminals for Satellite Communications

    NASA Technical Reports Server (NTRS)

    Huang, John

    1996-01-01

    Phased array antenna is beginning to play an important in the arena of mobile/satellite communications. Two examples of mobile terminal phased arrays will be shown. Their technical background, challenges, and cost drivers will be discussed. A possible solution to combat some of the deficiencies of the conventional phased array by exploiting the phased reflectarray technology will be briefly presented.

  4. Active retrodirective arrays for SPS beam pointing. [phase conjugation

    NASA Technical Reports Server (NTRS)

    Chernoff, R.

    1980-01-01

    The basic requirement of the SPS beam pointing system is that it deliver a certain amount of S-band (lambda = 12.5 cm) power to a 9.6 km diameter receiving rectenna on the ground. The power is transmitted from a 1.0 km diameter antenna array on the SPS, which is, for a rectenna at about plus or minus 40 deg. latitude, some 37.5x10 to the 6th power km distant. At the present time ARA's appear to be the best bet to realize this very stringent beam pointing requirement. An active retrodirective array (ARA) transmits a beam towards the apparent source of an illuminating signal called the pilot. The array produces, not merely reflects, RF power. Retrodirectivity is achieved by retransmitting from each element of the array a signal whose phase is the "conjugate" of that received by the element. Phase conjugate circuits and pointing errors in ARA's are described. Results obtained using a 2-element X-band ARA and an 8-element S-band ARA are included.

  5. AlGaAs phased array laser for optical communications

    NASA Technical Reports Server (NTRS)

    Carlson, N. W.

    1989-01-01

    Phased locked arrays of multiple AlGaAs diode laser emitters were investigated both in edge emitting and surface emitting configurations. CSP edge emitter structures, coupled by either evanescent waves or Y-guides, could not achieve the required powers (greater than or similar to 500 mW) while maintaining a diffraction limited, single lobed output beam. Indeed, although the diffraction limit was achieved in this type of device, it was at low powers and in the double lobed radiation pattern characteristic of out-of-phase coupling. Grating surface emitting (GSE) arrays were, therefore, investigated with more promising results. The incorporation of second order gratings in distribute Bragg reflector (DBR) structures allows surface emission, and can be configured to allow injection locking and lateral coupling to populate 2-D arrays that should be able to reach power levels commensurate with the needs of high performance, free space optical communications levels. Also, a new amplitude modulation scheme was developed for GSE array operation.

  6. The application of taylor weighting, digital phase shifters, and digital attenuators to phased-array antennas.

    SciTech Connect

    Brock, Billy C.

    2008-03-01

    Application of Taylor weighting (taper) to an antenna aperture can achieve low peak sidelobes, but combining the Taylor weighting with quantized attenuators and phase shifters at each radiating element will impact the performance of a phased-array antenna. An examination of array performance is undertaken from the simple point of view of the characteristics of the array factor. Design rules and guidelines for determining the Taylor-weighting parameters, the number of bits required for the digital phase shifter, and the dynamic range and number of bits required for the digital attenuator are developed. For a radar application, when each element is fed directly from a transmit/receive module, the total power radiated by the array will be reduced as a result of the taper. Consequently, the issue of whether to apply the taper on both transmit and receive configurations, or only on the receive configuration is examined with respect to two-way sidelobe performance.

  7. Wake Vortex Detection: Phased Microphone vs. Linear Infrasonic Array

    NASA Technical Reports Server (NTRS)

    Shams, Qamar A.; Zuckerwar, Allan J.; Sullivan, Nicholas T.; Knight, Howard K.

    2014-01-01

    Sensor technologies can make a significant impact on the detection of aircraft-generated vortices in an air space of interest, typically in the approach or departure corridor. Current state-of-the art sensor technologies do not provide three-dimensional measurements needed for an operational system or even for wake vortex modeling to advance the understanding of vortex behavior. Most wake vortex sensor systems used today have been developed only for research applications and lack the reliability needed for continuous operation. The main challenges for the development of an operational sensor system are reliability, all-weather operation, and spatial coverage. Such a sensor has been sought for a period of last forty years. Acoustic sensors were first proposed and tested by National Oceanic and Atmospheric Administration (NOAA) early in 1970s for tracking wake vortices but these acoustic sensors suffered from high levels of ambient noise. Over a period of the last fifteen years, there has been renewed interest in studying noise generated by aircraft wake vortices, both numerically and experimentally. The German Aerospace Center (DLR) was the first to propose the application of a phased microphone array for the investigation of the noise sources of wake vortices. The concept was first demonstrated at Berlins Airport Schoenefeld in 2000. A second test was conducted in Tarbes, France, in 2002, where phased microphone arrays were applied to study the wake vortex noise of an Airbus 340. Similarly, microphone phased arrays and other opto-acoustic microphones were evaluated in a field test at the Denver International Airport in 2003. For the Tarbes and Denver tests, the wake trajectories of phased microphone arrays and lidar were compared as these were installed side by side. Due to a built-in pressure equalization vent these microphones were not suitable for capturing acoustic noise below 20 Hz. Our group at NASA Langley Research Center developed and installed an

  8. Ultrasonic Phased Array Simulations of Welded Components at NASA

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.

    2009-01-01

    Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increasing role in the future for nondestructive evaluation in order to better understand the physics of the inspection process, to prove or disprove the feasibility for an inspection method or inspection scenario, for inspection optimization, for better understanding of experimental results, and for assessment of probability of detection. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles. Keywords: nondestructive evaluation, computational simulation, ultrasonics, weld, modeling, phased array

  9. Robotic inspection of fiber reinforced composites using phased array UT

    NASA Astrophysics Data System (ADS)

    Stetson, Jeffrey T.; De Odorico, Walter

    2014-02-01

    Ultrasound is the current NDE method of choice to inspect large fiber reinforced airframe structures. Over the last 15 years Cartesian based scanning machines using conventional ultrasound techniques have been employed by all airframe OEMs and their top tier suppliers to perform these inspections. Technical advances in both computing power and commercially available, multi-axis robots now facilitate a new generation of scanning machines. These machines use multiple end effector tools taking full advantage of phased array ultrasound technologies yielding substantial improvements in inspection quality and productivity. This paper outlines the general architecture for these new robotic scanning systems as well as details the variety of ultrasonic techniques available for use with them including advances such as wide area phased array scanning and sound field adaptation for non-flat, non-parallel surfaces.

  10. Stiffness of the extrafibrillar phase in staggered biological arrays.

    PubMed

    Bar-On, Benny; Wagner, H Daniel

    2012-08-17

    A number of important biological tissues such as nacre, tendon, and bone consist of staggered structural arrays as universal motifs. Such arrays usually include stiff fibril-like (or plateletlike, or needlelike) elements embedded in an extrafibrillar (XF) phase. This work discusses the effect of the stiffness of such an XF matrix on the elastic properties of the resulting staggered composite. In the case of most biological composites, this XF stiffness is hardly accessible and very little data are available. We develop an analysis based on previous analytical formulation that results in a relation between the XF modulus and the deformations of the staggered particles. This analysis is then used to back-calculate the yet unmeasured modulus of the XF phase from experimental deformation data, thereby providing a simple alternative to potentially complex direct measurements. This is demonstrated and validated for parallel-fiber bone tissue. PMID:23006404

  11. Monolithic Microwave Integrated Circuit (MMIC) Phased Array Demonstrated With ACTS

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Monolithic Microwave Integrated Circuit (MMIC) arrays developed by the NASA Lewis Research Center and the Air Force Rome Laboratory were demonstrated in aeronautical terminals and in mobile or fixed Earth terminals linked with NASA's Advanced Communications Technology Satellite (ACTS). Four K/Ka-band experimental arrays were demonstrated between May 1994 and May 1995. Each array had GaAs MMIC devices at each radiating element for electronic beam steering and distributed power amplification. The 30-GHz transmit array used in uplinks to ACTS was developed by Lewis and Texas Instruments. The three 20-GHz receive arrays used in downlinks from ACTS were developed in cooperation with the Air Force Rome Laboratory, taking advantage of existing Air Force integrated-circuit, active-phased-array development contracts with the Boeing Company and Lockheed Martin Corporation. Four demonstrations, each related to an application of high interest to both commercial and Department of Defense organizations, were conducted. The location, type of link, and the data rate achieved for each of the applications is shown. In one demonstration-- an aeronautical terminal experiment called AERO-X--a duplex voice link between an aeronautical terminal on the Lewis Learjet and ACTS was achieved. Two others demonstrated duplex voice links (and in one case, interactive video links as well) between ACTS and an Army high-mobility, multipurpose wheeled vehicle (HMMWV, or "humvee"). In the fourth demonstration, the array was on a fixed mount and was electronically steered toward ACTS. Lewis served as project manager for all demonstrations and as overall system integrator. Lewis engineers developed the array system including a controller for open-loop tracking of ACTS during flight and HMMWV motion, as well as a laptop data display and recording system used in all demonstrations. The Jet Propulsion Laboratory supported the AERO-X program, providing elements of the ACTS Mobile Terminal. The successful

  12. Estimating Transmitted-Signal Phase Variations for Uplink Array Antennas

    NASA Technical Reports Server (NTRS)

    Paal, Leslie; Mukai, Ryan; Vilntrotter, Victor; Cornish, Timothy; Lee, Dennis

    2009-01-01

    A method of estimating phase drifts of microwave signals distributed to, and transmitted by, antennas in an array involves the use of the signals themselves as phase references. The method was conceived as part of the solution of the problem of maintaining precise phase calibration required for proper operation of an array of Deep Space Network (DSN) antennas on Earth used for communicating with distant spacecraft at frequencies between 7 and 8 GHz. The method could also be applied to purely terrestrial phased-array radar and other radio antenna array systems. In the DSN application, the electrical lengths (effective signal-propagation path lengths) of the various branches of the system for distributing the transmitted signals to the antennas are not precisely known, and they vary with time. The variations are attributable mostly to thermal expansion and contraction of fiber-optic and electrical signal cables and to a variety of causes associated with aging of signal-handling components. The variations are large enough to introduce large phase drifts at the signal frequency. It is necessary to measure and correct for these phase drifts in order to maintain phase calibration of the antennas. A prior method of measuring phase drifts involves the use of reference-frequency signals separate from the transmitted signals. A major impediment to accurate measurement of phase drifts over time by the prior method is the fact that although DSN reference-frequency sources separate from the transmitting signal sources are stable and accurate enough for most DSN purposes, they are not stable enough for use in maintaining phase calibrations, as required, to within a few degrees over times as long as days or possibly even weeks. By eliminating reliance on the reference-frequency subsystem, the present method overcomes this impediment. In a DSN array to which the present method applies (see figure), the microwave signals to be transmitted are generated by exciters in a signal

  13. Improved Titanium Billet Inspection Sensitivity through Optimized Phased Array Design, Part II: Experimental Validation and Comparative Study with Multizone

    SciTech Connect

    Hassan, W.; Vensel, F.; Knowles, B.

    2006-03-06

    The inspection of critical rotating components of aircraft engines has made important advances over the last decade. The development of Phased Array (PA) inspection capability for billet and forging materials used in the manufacturing of critical engine rotating components has been a priority for Honeywell Aerospace. The demonstration of improved PA inspection system sensitivity over what is currently used at the inspection houses is a critical step in the development of this technology and its introduction to the supply base as a production inspection. As described in Part I (in these proceedings), a new phased array transducer was designed and manufactured for optimal inspection of eight inch diameter Ti-6Al-4V billets. After confirming that the transducer was manufactured in accordance with the design specifications a validation study was conducted to assess the sensitivity improvement of the PAI over the current capability of Multi-zone (MZ) inspection. The results of this study confirm the significant ({approx_equal} 6 dB in FBH number sign sensitivity) improvement of the PAI sensitivity over that of MZI.

  14. Method for calculating longitudinal microstrip antennas in planar phased arrays

    NASA Astrophysics Data System (ADS)

    Indenbom, M. V.

    The characteristics of longitudinal microstrip antennas in a planar phased array are examined on the basis of the application of the finite element method to an integral equation for the 'charge' on the microstrip line. Microstrip dipoles, and Yagi and log-periodic antennas are examples of such radiators. The analysis takes into account the complex configuration of the conductors, both current components, and the presence of dielectric substrates and a protective coating.

  15. Adaptive multibeam phased array design for a Spacelab experiment

    NASA Technical Reports Server (NTRS)

    Noji, T. T.; Fass, S.; Fuoco, A. M.; Wang, C. D.

    1977-01-01

    The parametric tradeoff analyses and design for an Adaptive Multibeam Phased Array (AMPA) for a Spacelab experiment are described. This AMPA Experiment System was designed with particular emphasis to maximize channel capacity and minimize implementation and cost impacts for future austere maritime and aeronautical users, operating with a low gain hemispherical coverage antenna element, low effective radiated power, and low antenna gain-to-system noise temperature ratio.

  16. Diffraction coupled phase-locked semiconductor laser array

    NASA Technical Reports Server (NTRS)

    Katz, J.; Margalit, S.; Yariv, A.

    1983-01-01

    A new monolithic, diffraction coupled phase-locked semiconductor laser array has been fabricated. Stable narrow far-field patterns (approximately 3 deg) and peak power levels of 1 W have been obtained for 100-micron-wide devices with threshold currents as low as 250 mA. Such devices may be useful in applications where high power levels and stable radiation patterns are needed.

  17. Large-Aperture Membrane Active Phased-Array Antennas

    NASA Technical Reports Server (NTRS)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

  18. Phase-type quantum-dot-array diffraction grating

    SciTech Connect

    Wang Chuanke; Kuang Longyu; Wang Zhebin; Cao Leifeng; Liu Shenye; Ding Yongkun; Wang Deqiang; Xie Changqing; Ye Tianchun; Hu Guangyue

    2008-12-15

    A novel phase-type quantum-dot-array diffraction grating (QDADG) is reported. In contrast to an earlier amplitude-type QDADG [C. Wang et al., Rev. Sci. Instrum. 78, 053503 (2007)], the new phase-type QDADG would remove the zeroth order diffraction at some certain wavelength, as well as suppressing the higher-order diffractions. In this paper, the basic concept, the fabrication, the calibration techniques, and the calibration results are presented. Such a grating can be applied in the research fields of beam splitting, laser probe diagnostics, and so on.

  19. 64-element intraluminal ultrasound cylindrical phased array for transesophageal thermal ablation under fast MR temperature mapping: an ex vivo study

    PubMed Central

    Melodelima, David; Salomir, Rares; Mougenot, Charles; Moonen, Chrit; Cathignol, Dominique

    2006-01-01

    This work was undertaken to investigate the feasibility of using a cylindrical phased array for transoesophaeal thermal ablation under Magnetic Resonance (MR) imaging guidance. Sixty four transducers (0.45-mm wide by 15-mm tall), operating at 4.6 MHz, were spread around the periphery of a 10.6-mm diameter cylinder. The head of the applicator was covered with a 65-μm thick latex balloon attached using watertight seals. This envelope was inflated with degassed water to provide acoustic coupling between the transducer and the tissues. The underlying operating principle of this applicator is to rotate a plane ultrasound beam electronically. For this purpose, eight adjacent transducers were excited with appropriate delay times so as to generate a plane wave. The exposure direction was changed by exciting a different set of eight elements. Ex vivo experiments conducted on 47 samples of pig liver under MR temperature monitoring demonstrated the ability of this applicator to generate cylindrical or sector-based coagulation necroses at depths up to 19 mm with excellent angular precision by applying 20 W/cm 2. MR-thermometry was performed in “real-time” with segmented echo-planar imaging gradient echo sequences. The temporal resolution was approximately 3s/image. The average value for the temperature baseline in liver tissue close to the applicator was 0.3°C (±0.6°C). The thermal dose delivered in tissues was computed online during temperature imaging. Excellent MR compatibility was demonstrated, all MR acquisitions were performed without susceptibility artefacts or radiofrequency interferences with the ultrasound device. Thermal lesions identified on post-treatment follow up showed good correlation with on line MR thermometry data. The individual differences between measurements performed visually and using MRI thermal dose maps were about 11% of volume. This study demonstrated the feasibility of thermal ablation using a phased array intraluminal ultrasound

  20. Phased-array-fed antenna configuration study. Volume 1: Technology assessment

    NASA Technical Reports Server (NTRS)

    Sorbello, R. M.; Zaghloul, A. I.; Lee, B. S.; Siddiqi, S.; Geller, B. D.; Gerson, H. I.; Srinivas, D. N.

    1983-01-01

    The status of the technologies for phased-array-fed dual reflector systems is reviewed. The different aspects of these technologies, including optical performances, phased array systems, problems encountered in phased array design, beamforming networks, MMIC design and its incorporation into waveguide systems, reflector antenna structures, and reflector deployment mechanisms are addressed.

  1. Microinterferometer transducer

    DOEpatents

    Corey, III, Harry S.

    1979-01-01

    An air-bearing microinterferometer transducer is provided for increased accuracy, range and linearity over conventional displacement transducers. A microinterferometer system is housed within a small compartment of an air-bearing displacement transducer housing. A movable cube corner reflector of the interferometer is mounted to move with the displacement gauging probe of the transducer. The probe is disposed for axial displacement by means of an air-bearing. Light from a single frequency laser is directed into an interferometer system within the transducer housing by means of a self-focusing fiber optic cable to maintain light coherency. Separate fringe patterns are monitored by a pair of fiber optic cables which transmit the patterns to a detecting system. The detecting system includes a bidirectional counter which counts the light pattern fringes according to the direction of movement of the probe during a displacement gauging operation.

  2. Wideband Single Crystal Transducer for Bone Characterization

    NASA Technical Reports Server (NTRS)

    Sahul, Raffi

    2015-01-01

    Phase II objectives: Optimize the Phase I transducer for sensitivity; Test different transmit signals for optimum performance; Demonstrate compatibility with electronics; Confirm additional transducer capabilities over conventional systems by calibrating with other methods.

  3. Infinite phased array of microstrip dipoles in two layers

    NASA Astrophysics Data System (ADS)

    Castaneda, Jesus A.

    1989-01-01

    A method has been devised for the analysis of the infinite printed strip dipole array in a two layer microstrip substrate structure. The complete dynamic Green's function appropriate to the two-layer substrate-superstrate structure was used in the formulation of the method of moments solution. In this way all the substrate effects, including the surface wave related phenomena, have been included in the development and solution. The solution provides a means by which the most important performance characteristics of the finite-but-large phase-scanned microstrip array can be studied. Attention has been focused on the characterization of the active input impedance as a function of the equivalent scan angle.

  4. Phased array antenna investigation for CubeSat size satellites

    NASA Astrophysics Data System (ADS)

    Dang, Kien

    Increasing bandwidth of the communication link has been a challenge for CubeSat class satellite. Traditional satellites usually utilizes high gain antennas for this purpose, but these antenna are rarely seen in CubeSat because of its power, volume and weight constraints. To solve these issues, this dissertation presents a phased array antenna system prototyped at 2.45 GHz with 17.7 dBi gain at broadside, 14.2 dBi at +/-40°, 50 MHz bandwidth, and fits on a side of a 3U CubeSat. The gain can be increased by adding more antenna elements into the array as needed. Testing for electronic beam steering has been completed and detailed results will be presented.

  5. Partially coherent twisted states in arrays of coupled phase oscillators

    SciTech Connect

    Omel'chenko, Oleh E.; Wolfrum, Matthias; Laing, Carlo R.

    2014-06-15

    We consider a one-dimensional array of phase oscillators with non-local coupling and a Lorentzian distribution of natural frequencies. The primary objects of interest are partially coherent states that are uniformly “twisted” in space. To analyze these, we take the continuum limit, perform an Ott/Antonsen reduction, integrate over the natural frequencies, and study the resulting spatio-temporal system on an unbounded domain. We show that these twisted states and their stability can be calculated explicitly. We find that stable twisted states with different wave numbers appear for increasing coupling strength in the well-known Eckhaus scenario. Simulations of finite arrays of oscillators show good agreement with results of the analysis of the infinite system.

  6. Low Noise Performance Perspectives Of Wideband Aperture Phased Arrays

    NASA Astrophysics Data System (ADS)

    Woestenburg, E. E. M.; Kuenen, J. C.

    2004-06-01

    A general analysis of phased array noise properties and measurements, applied to one square meter tiles of the Thousand Element Array (THEA), has resulted in a procedure to define the noise budget for a THEA-tile (Woestenburg and Dijkstra, 2003). The THEA system temperature includes LNA and receiver noise, antenna connecting loss, noise coupling between antenna elements and other possible contributions. This paper discusses the various noise contributions to the THEA system temperature and identifies the areas where improvement can be realized. We will present better understanding of the individual noise contributions using measurements and analysis of single antenna/receiver elements. An improved design for a 1-m2 Low Noise Tile (LNT) will be discussed and optimized low noise performance for the LNT is presented. We will also give future perspectives of the noise performance for such tiles, in relation to the requirements for SKA in the 1 GHz frequency range.

  7. Improved Phased Array Imaging of a Model Jet

    NASA Technical Reports Server (NTRS)

    Dougherty, Robert P.; Podboy, Gary G.

    2010-01-01

    An advanced phased array system, OptiNav Array 48, and a new deconvolution algorithm, TIDY, have been used to make octave band images of supersonic and subsonic jet noise produced by the NASA Glenn Small Hot Jet Acoustic Rig (SHJAR). The results are much more detailed than previous jet noise images. Shock cell structures and the production of screech in an underexpanded supersonic jet are observed directly. Some trends are similar to observations using spherical and elliptic mirrors that partially informed the two-source model of jet noise, but the radial distribution of high frequency noise near the nozzle appears to differ from expectations of this model. The beamforming approach has been validated by agreement between the integrated image results and the conventional microphone data.

  8. Guided wave phased array sensor tuning for improved defect detection and characterization

    NASA Astrophysics Data System (ADS)

    Philtron, Jason H.; Rose, Joseph L.

    2014-03-01

    Ultrasonic guided waves are finding increased use in a variety of Nondestructive Evaluation and Structural Health Monitoring applications due to their efficiency in defect detection using a sensor at a single location to inspect a large area of a structure and an ability to inspect hidden and coated areas for example. With a thorough understanding of guided wave mechanics, researchers can predict which guided wave modes will have a high probability of success in a particular nondestructive evaluation application. For example, in a sample problem presented here to access bond integrity, researchers may choose to use a guided wave mode which has high in-plane displacement, stress, or other feature at the interface. However, since material properties used for modeling work may not be precise for the development of dispersion curves, in many cases guided wave mode and frequency selection should be adjusted for increased inspection efficiency in the field. In this work, a phased array comb transducer is used to sweep over phase velocity - frequency space to tune mode excitation for improved defect characterization performance. A thin polycarbonate layer bonded to a thick metal plate is considered with a contaminated surface prior to bonding. Physicallybased features are used to correlate wave signals with defect detection. Features assessed include arrival time and the frequency of maximum amplitude. A pseudo C-scan plot is presented which can be used to simplify data analysis. Excellent results are obtained.

  9. High-speed 32×32 MEMS optical phased array

    NASA Astrophysics Data System (ADS)

    Megens, Mischa; Yoo, Byung-Wook; Chan, Trevor; Yang, Weijian; Sun, Tianbo; Chang-Hasnain, Connie J.; Wu, Ming C.; Horsley, David A.

    2014-03-01

    Optical phased arrays (OPAs) with fast response time are of great interest for various applications such as displays, free space optical communications, and lidar. Existing liquid crystal OPAs have millisecond response time and small beam steering angle. Here, we report on a novel 32×32 MEMS OPA with fast response time (<4 microseconds), large field of view (+/-2°), and narrow beam divergence (0.1°). The OPA is composed of high-contrast grating (HCG) mirrors which function as phase shifters. Relative to beam steering systems based on a single rotating MEMS mirror, which are typically limited to bandwidths below 50 kHz, the MEMS OPA described here has the advantage of greatly reduced mass and therefore achieves a bandwidth over 500 kHz. The OPA is fabricated using deep UV lithography to create submicron mechanical springs and electrical interconnects, enabling a high (85%) fill-factor. Each HCG mirror is composed of only a single layer of polysilicon and achieves >99% reflectivity through the use of a subwavelength grating patterned into the mirror's polysilicon surface. Conventional metal-coated MEMS mirrors must be thick (1- 50 μm) to prevent warpage arising from thermal and residual stress. The single material construction used here results in a high degree of flatness even in a thin 400 nm HCG mirror. Beam steering is demonstrated using binary phase patterns and is accomplished with the help of a closed-loop phase control system based on a phase-shifting interferometer that provides in-situ measurement of the phase shift of each mirror in the array.

  10. High density pixel array

    NASA Technical Reports Server (NTRS)

    Wiener-Avnear, Eliezer (Inventor); McFall, James Earl (Inventor)

    2004-01-01

    A pixel array device is fabricated by a laser micro-milling method under strict process control conditions. The device has an array of pixels bonded together with an adhesive filling the grooves between adjacent pixels. The array is fabricated by moving a substrate relative to a laser beam of predetermined intensity at a controlled, constant velocity along a predetermined path defining a set of grooves between adjacent pixels so that a predetermined laser flux per unit area is applied to the material, and repeating the movement for a plurality of passes of the laser beam until the grooves are ablated to a desired depth. The substrate is of an ultrasonic transducer material in one example for fabrication of a 2D ultrasonic phase array transducer. A substrate of phosphor material is used to fabricate an X-ray focal plane array detector.

  11. RF MEMS Phase Shifters and their Application in Phase Array Antennas

    NASA Technical Reports Server (NTRS)

    Scardelletti, Maximilian; Ponchak, George E.; Zaman, Afroz J.; Lee, Richard Q.

    2005-01-01

    Electronically scanned arrays are required for space based radars that are capable of tracking multiple robots, rovers, or other assets simultaneously and for beam-hopping communication systems between the various assets. ^Traditionally, these phased array antennas used GaAs Monolithic Microwave Integrated Circuit (MMIC) phase shifters, power amplifiers, and low noise amplifiers to amplify and steer the beam, but the development of RF MEMS switches over the past ten years has enabled system designers to consider replacing the GaAs MMIC phase shifters with RF Micro-Electro Mechanical System (MEMS) phase shifters. In this paper, the implication of replacing the relatively high loss GaAs MMICs with low loss MEMS phase shifters is investigated.

  12. Novel Phased Array Scanning Employing A Single Feed Without Using Individual Phase Shifters

    NASA Technical Reports Server (NTRS)

    Host, Nicholas K.; Chen, Chi-Chih; Volakis, John L.; Miranda, Felix A.

    2012-01-01

    Phased arrays afford many advantages over mechanically steered systems. However, they are also more complex, heavy, and most of all costly. The high cost mainly originates from the complex feeding structure. This paper proposes a novel feeding scheme to eliminate all phase shifters and achieve scanning via one-dimensional motion. Beam scanning is achieved via a series fed array incorporating feeding transmission lines whose wave velocity can be mechanically adjusted. Along with the line design, ideal element impedances to be used in conjunction with the line are derived. Practical designs are shown which achieve scanning to +/-30deg from boresight. Finally, a prototype is fabricated and measured, demonstrating the concept.

  13. Through Weld Inspection of Wrought Stainless Steel Piping Using Phased Arrays

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.; Doctor, Steven R.

    2004-12-31

    Outline: Discuss far-side weld problem and phased array techniques applied. Describe laboratory work on flawed piping specimens using L- and S-wave arrays and provide synopsis of results. Discuss conclusions ofr capability of phased array as applied to austenitic welds. Research Approach: Evaluate phased arrays on unifornly-welded piping specimens. Apply best methods to non-uniform welds. Correlate acoustic responses as function of weld microstructures.

  14. Ultrasonic Phased Array Inspection Simulations of Welded Components at NASA

    NASA Technical Reports Server (NTRS)

    Roth, D. J.; Tokars, R. P.; Martin, R. E.; Rauser, R. W.; Aldrin, J. C.; Schumacher, E. J.

    2009-01-01

    Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increased role in the future for nondestructive evaluation in order to better understand the physics of the inspection process and help explain the experimental results. It will also help to prove or disprove the feasibility for an inspection method or inspection scenario, help optimize inspections, and allow to a first approximation limits of detectability. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles.

  15. Welding Process Feedback and Inspection Optimization Using Ultrasonic Phased Arrays

    NASA Astrophysics Data System (ADS)

    Hopkins, D. L.; Neau, G. N.; Davis, W. B.

    2009-03-01

    Measurements performed on friction-stir butt welds in aluminum and resistance spot welds in galvanized steel are used to illustrate how ultrasonic phased arrays can be used to provide high-resolution images of welds. Examples are presented that demonstrate how information extracted from the ultrasonic signals can be used to provide reliable feedback to welding processes. Modeling results are used to demonstrate how weld inspections can be optimized using beam-forming strategies that help overcome the influence of surface conditions and part distortion.

  16. Phase transition of dissipative Josephson arrays in a magnetic field

    SciTech Connect

    Kampf, A.; Schoen, G.

    1988-04-01

    The phase diagram of an array of Josephson junctions in a transverse magnetic field is investigated. The capacitive interactions of charges on the superconducting islands and the associated quantum-mechanical effects, as well as the dissipation due to the flow of normal Ohmic currents, are taken into account. The mean-field approximation of this system can be mapped onto the tight-binding Schroedinger equation for Bloch electrons in a magnetic field, which had been analyzed by Hofstadter. We show how the transition temperature depends on the dissipation and the charging energy.

  17. Performance characteristics of phased array and thinned aperture optical telescopes

    NASA Technical Reports Server (NTRS)

    Harvey, James E.; Rockwell, Richard A.

    1987-01-01

    While phased telescope arrays for general-purpose broadband imaging applications suffer severe sensitivity losses and field-of-view limitations, thinned-aperture telescopes consisting of a dilute, segmented primary mirror with a common secondary mirror are viable second-generation space telescope configurational possibilities yielding resolution and sensitivity an order of magnitude greater than those of the Hubble Space Telescope. Attention is given to thinned-aperture optical systems' image quality characterization problems; the 'practical resolution limit' image quality criterion proposed is defined as the reciprocal of the spatial frequency within which no zeros occur in the modulation transfer function.

  18. Subtyping of breast cancer using reverse phase protein arrays.

    PubMed

    Sonntag, Johanna; Schlüter, Kerstin; Bernhardt, Stephan; Korf, Ulrike

    2014-12-01

    Reverse phase protein arrays (RPPAs) present a robust and sensitive high capacity platform for targeted proteomics that relies on highly specific antibodies to obtain a quantitative readout regarding phosphorylation state and abundance of proteins of interest. This review summarizes the current state of RPPA-based proteomic profiling of breast cancer in the context of existing preanalytical strategies and sample preparation protocols. RPPA-based subtypes identified so far are compared to those obtained by other approaches such as immunohistochemistry, genomics and transcriptomics. Special attention is given to discussing the potential of RPPA for biomarker discovery and biomarker validation. PMID:25400094

  19. KPAF (K-band phased array feed) instrument concept

    NASA Astrophysics Data System (ADS)

    Locke, Lisa; Claude, Stéphane; Bornemann, Jens; Henke, Doug; Di Francesco, James; Jiang, Frank; Garcia, Dominic; Wevers, Ivan; Niranjanan, Pat

    2014-07-01

    Astronomical surveys are demanding more throughput from telescope receivers. Currently, microwave/millimeter telescopes with mature cryogenic single pixel receivers are upgrading to multi-pixel receivers by replacing the conventional feed horns with phased array feeds (PAFs) to increase the field of view and, thus, imaging speeds. This step in astronomy instrumentation has been taken by only a few research laboratories world-wide and primarily in Lband (0.7-1.5 GHz). We present a K-band (18-26 GHz) 5x5 modular PAF to demonstrate the feasibility of higher frequency receiving arrays. The KPAF system includes a tapered slot antenna array, a cryogenic commercial GaAs MMIC amplifier block, and a mixing stage to down-convert to L band for an existing beamformer. The noise temperature and power budget are outlined. Full antenna S-parameters and far-field beam patterns are simulated and measured using both planar near-field and far-field techniques. Cryogenic and room temperature amplifier noise measurements with varying bias levels are presented.

  20. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S.

    2000-01-01

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

  1. MSAT-X electronically steered phased array antenna system

    NASA Technical Reports Server (NTRS)

    Chung, H. H.; Foy, W.; Schaffner, G.; Pagels, W.; Vayner, M.; Nelson, J.; Peng, S. Y.

    1988-01-01

    A low profile electronically steered phased array was successfully developed for the Mobile Satellite Experiment Program (MSAT-X). The newly invented cavity-backed printed crossed-slot was used as the radiating element. The choice of this element was based on its low elevation angle gain coverage and low profile. A nineteen-way radial type unequal power divider and eighteen three-bit diode phase shifters constitute the beamformer module which is used to scan the beams electronically. A complete hybrid mode pointing system was also developed. The major features of the antenna system are broad coverage, low profile, and fast acquisition and tracking performance, even under fading conditions. Excellent intersatellite isolation (better than 26 dB) was realized, which will provide good quality mobile satellite communication in the future.

  2. Cylindrical Antenna With Partly Adaptive Phased-Array Feed

    NASA Technical Reports Server (NTRS)

    Hussein, Ziad; Hilland, Jeff

    2003-01-01

    A proposed design for a phased-array fed cylindrical-reflector microwave antenna would enable enhancement of the radiation pattern through partially adaptive amplitude and phase control of its edge radiating feed elements. Antennas based on this design concept would be attractive for use in radar (especially synthetic-aperture radar) and other systems that could exploit electronic directional scanning and in which there are requirements for specially shaped radiation patterns, including ones with low side lobes. One notable advantage of this design concept is that the transmitter/ receiver modules feeding all the elements except the edge ones could be identical and, as a result, the antenna would cost less than in the cases of prior design concepts in which these elements may not be identical.

  3. Project PARAS: Phased array radio astronomy from space

    NASA Technical Reports Server (NTRS)

    Nuss, Kenneth; Hoffmann, Christopher; Dungan, Michael; Madden, Michael; Bendakhlia, Monia

    1992-01-01

    An orbiting radio telescope is proposed which, when operated in a very long baseline interferometry (VLBI) scheme, would allow higher than currently available angular resolution and dynamic range in the maps and the ability to observe rapidly changing astronomical sources. Using passive phased array technology, the proposed design consists of 656 hexagonal modules forming a 150-m diameter antenna dish. Each observatory module is largely autonomous, having its own photovoltaic power supply and low-noise receiver and processor for phase shifting. The signals received by the modules are channeled via fiber optics to the central control computer in the central bus module. After processing and multiplexing, the data are transmitted to telemetry stations on the ground. The truss frame supporting each observatory panel is a novel hybrid structure consisting of a bottom graphite/epoxy tubular triangle and rigidized inflatable Kevlar tubes connecting the top observatory panel and the bottom triangle. Attitude control and station keeping functions will be performed by a system of momentum wheels in the bus and four propulsion modules located at the compass points on the periphery of the observatory dish. Each propulsion module has four monopropellant thrusters and four hydrazine arcjets, the latter supported by either a photovoltaic array or a radioisotope thermoelectric generator. The total mass of the spacecraft is about 20,500 kg.

  4. Influence of resonant transducer variations on long range guided wave monitoring of rail track

    NASA Astrophysics Data System (ADS)

    Loveday, Philip W.; Long, Craig S.

    2016-02-01

    The ability of certain guided wave modes to propagate long distances in continuously welded rail track is exploited in permanently installed monitoring systems. Previous work demonstrated that reflections from thermite welds could be measured at distances of the order of 1 km from a transducer array. The availability of numerous thermite welds is useful during the development of a monitoring system as real defects are not available. Measurements of reflections from welds were performed over an eleven month period with two permanently installed transducers. Phased array processing was performed and the true location of a weld is indicated by a strong reflection but there is generally also a smaller, spurious replica reflection, at the same distance but in the incorrect direction. In addition, the relative reflection from different welds appears to change over time. The influence of differences between the two resonant transducers was investigated using a model. It was found that estimating the attenuation in either direction and scaling the reflections in either direction decreased the variability in the reflection measurements. Transducer interaction effects, where the transducer closer to the weld records a greater reflection than the second transducer were observed and can be used to determine the direction of a weld. This feature was used to demonstrate a simple alternative to phased array processing that can be used with resonant transducers.

  5. Simulation of atmospheric turbulence compensation through piston-only phase control of a laser phased array

    NASA Astrophysics Data System (ADS)

    McCrae, Jack E.; Van Zandt, Noah; Cusumano, Salvatore J.; Fiorino, Steven T.

    2013-05-01

    Beam propagation from a laser phased array system through the turbulent atmosphere is simulated and the ability of such a system to compensate for the atmosphere via piston-only phase control of the sub-apertures is evaluated. Directed energy (DE) applications demand more power than most lasers can produce, consequently many schemes for high power involve combining the beams from many smaller lasers into one. When many smaller lasers are combined into a phased array, phase control of the individual sub-apertures will be necessary to create a high-quality beam. Phase control of these sub-apertures could then be used to do more, such as focus, steer, and compensate for atmospheric turbulence. Atmospheric turbulence is well known to degrade the performance of both imaging systems and laser systems. Adaptive optics can be used to mitigate this degradation. Adaptive optics ordinarily involves a deformable mirror, but with phase control on each sub-aperture the need for a deformable mirror is eliminated. The simulation conducted here evaluates performance gain for a 127 element phased array in a hexagonal pattern with piston-only phase control on each element over an uncompensated array for varying levels of atmospheric turbulence. While most simulations were carried out against a 10 km tactical scenario, the turbulence profile was adjusted so performance could be evaluated as a function of the Fried Parameter (r0) and the log-amplitude variance somewhat independently. This approach is demonstrated to be generally effective with the largest percentage improvement occurring when r0 is close to the sub-aperture diameter.

  6. Vibro-acoustography with 1.75D ultrasound array transducer for detection and localization of permanent prostate brachytherapy seeds: ex vivo study

    NASA Astrophysics Data System (ADS)

    Mehrmohammadi, Mohammad; Alizad, Azra; Kinnick, Randall R.; Davis, Brian J.; Fatemi, Mostafa

    2013-03-01

    Effective brachytherapy procedures require precise placement of radioactive seeds in the prostate. Currently, transrectal ultrasound (TRUS) imaging is one of the main intraoperative imaging modalities to assist physicians in placement of brachytherapy seeds. However, the seed detection rate with TRUS is poor mainly because ultrasound imaging is highly sensitive to variations in seed orientation. The purpose of this study is to investigate the abilities of a new acoustic radiation force imaging modality, vibro-acoustography (VA), equipped with a 1.75D array transducer and implemented on a customized clinical ultrasound scanner, to image and localize brachytherapy seeds in prostatic tissue. To perform experiments, excised cadaver prostate specimens were implanted with dummy brachytherapy seeds, and embedded in tissue mimicking gel to simulate the properties of the surrounding soft tissues. The samples were scanned using the VA system and the resulting VA signals were used to reconstruct VA images at several depths inside the tissue. To further evaluate the performance of VA in detecting seeds, X-ray computed tomography (CT) images of the same tissue sample, were obtained and used as a gold-standard to compare the number of seeds detected by the two methods. Our results indicate that VA is capable of imaging of brachytherapy seeds with accuracy and high contrast, and can detect a large percentage of the seeds implanted within the tissue samples.

  7. Phase conjugation method and apparatus for an active retrodirective antenna array

    NASA Technical Reports Server (NTRS)

    Tausworthe, R. C.; Chernoff, R. C. (Inventor)

    1979-01-01

    An active retrodirective antenna array wherein a reference array element is used to generate a phase reference which is replicated at succeeding elements of the array. Each element of the array is associated with a phase regeneration circuit and the phase conjugation circuitry of an adjacent element. In one implementation, the phase reference circuit operates on the input signal at the reference element, a voltage controlled oscillator (VCO) output signal and the input pilot signal at the next array element received from a transmission line. By proper filtering and mixing, a phase component may be produced to which the VCO may be locked to produce the phase conjugate of the pilot signal at the next array element plus a transmission line delay. In another implementation, particularly suited for large arrays in space, two different input pilot frequencies are employed.

  8. W-band Phased Array Systems using Silicon Integrated Circuits

    NASA Astrophysics Data System (ADS)

    Kim, Sang Young

    This thesis presents the silicon-based on-chip W-band phased array systems. An improved quadrature all-pass filter (QAF) and its implementation in 60--80 GHz active phase shifter using 0.13 microm SiGe BiCMOS technology is presented. It is demonstrated that with the inclusion of an Rs/R in the high Q branches of C and L, the sensitivity to the loading capacitance, therefore the I/Q phase and amplitude errors are minimized. This technique is especially suited for wideband millimeter-wave circuits where the loading capacitance (CL) is comparable to the filter capacitance (C). A prototype 60--80 GHz active phased shifter using the improved QAF is demonstrated. The overall chip size is 1.15 x 0.92 mm2 with the power consumption of 108 mW. The measured S11 and S22 are < -10 dB at 60--80 GHz and 60--73 GHz, respectively. The measured average power gain is 11.0--14.7 dB at 60--79 GHz with the rms gain error of < 1.3 dB at 60--78 GHz for 4-bit phase states. And the rms phase error is < 9.1 degree at 60--78.5 GHz showing wideband 4-bit performance. The measured NF is 9--11.6 dB at 63--75 GHz and the measured P 1dB is -27 dBm at 70 GHz. In another project, a 67--78 GHz 4-bit passive phase shifter using 0.13 microm CMOS switches is demonstrated. The phase shifter is based on a low-pass pi-network. The chip size is 0.45 x 0.3 mm2 without pads and consumes virtually no power. The measured S11 and S22 is < -10 dB at 67--81 GHz for all 16 phase states. The measured gain of 4-bit phase shifter is -19.2 +/- 3.7 dB at 77 GHz with the rms gain error of < 11.25 degree at 67--78 GHz. And the measured rms phase error is < 2.5 dB at 67--78 GHz. The measured P1dB is > 8 dBm and the simulated IIP3 is > 22 dBm. A low-power 76--84 GHz 4-element phased array receiver using the designed passive phase shifter is presented. The power consumption is minimized by using a single-ended design and alternating the amplifiers and phase shifter cells to result in a low noise figure at a low power

  9. Influence of phase delay profile on diffraction efficiency of liquid crystal optical phased array

    NASA Astrophysics Data System (ADS)

    Xu, Lin; Zhang, Jian; Wu, Li Ying

    2009-06-01

    The hardware structure and driving voltage of liquid crystal optical phased array (LCOPA) devices determine the produced phase delay characteristics. The phase delay profile influences directly the device's diffraction efficiency. In this paper, a sawtooth-shaped phase delay model of LCOPA was proposed to analyze quantitatively the influence factors of diffraction efficiency employing Fourier optics theory. Analysis results show that flyback region size is the main factor that affects diffraction efficiency. The influence extent varies with different maximum-phase-delays and grating periods. There exists an optimized curve between maximum-phase-delay and flyback region, and between maximum-phase-delay and grating period, individually. The smaller the grating period is or the larger the flyback region is, the more evident the optimization effect becomes, and the maximum increase ratio is up to 16%. Some feasible experiments were done to test theoretical analysis, and the experimental results agreed with the analysis results.

  10. High power compatible internally sensed optical phased array.

    PubMed

    Roberts, Lyle E; Ward, Robert L; Francis, Samuel P; Sibley, Paul G; Fleddermann, Roland; Sutton, Andrew J; Smith, Craig; McClelland, David E; Shaddock, Daniel A

    2016-06-13

    The technical embodiment of the Huygens-Fresnel principle, an optical phased array (OPA) is an arrangement of optical emitters with relative phases controlled to create a desired beam profile after propagation. One important application of an OPA is coherent beam combining (CBC), which can be used to create beams of higher power than is possible with a single laser source, especially for narrow linewidth sources. Here we present an all-fiber architecture that stabilizes the relative output phase by inferring the relative path length differences between lasers using the small fraction of light that is back-reflected into the fiber at the OPA's glass-air interface, without the need for any external sampling optics. This architecture is compatible with high power continuous wave laser sources (e.g., fiber amplifiers) up to 100 W per channel. The high-power compatible internally sensed OPA was implemented experimentally using commercial 15 W fiber amplifiers, demonstrating an output RMS phase stability of λ/194, and the ability to steer the beam at up to 10 kHz. PMID:27410363

  11. Optimizing an ELF/VLF Phased Array at HAARP

    NASA Astrophysics Data System (ADS)

    Fujimaru, S.; Moore, R. C.

    2013-12-01

    The goal of this study is to maximize the amplitude of 1-5 kHz ELF/VLF waves generated by ionospheric HF heating and measured at a ground-based ELF/VLF receiver. The optimization makes use of experimental observations performed during ELF/VLF wave generation experiments at the High-frequency Active Auroral Research Program (HAARP) Observatory in Gakona, Alaska. During these experiments, the amplitude, phase, and propagation delay of the ELF/VLF waves were carefully measured. The HF beam was aimed at 15 degrees zenith angle in 8 different azimuthal directions, equally spaced in a circle, while broadcasting a 3.25 MHz (X-mode) signal that was amplitude modulated (square wave) with a linear frequency-time chirp between 1 and 5 kHz. The experimental observations are used to provide reference amplitudes, phases, and propagation delays for ELF/VLF waves generated at these specific locations. The presented optimization accounts for the trade-off between duty cycle, heated area, and the distributed nature of the source region in order to construct a "most efficient" phased array. The amplitudes and phases generated by modulated heating at each location are combined in post-processing to find an optimal combination of duty cycle, heating location, and heating order.

  12. Experimental assessment of phased-array heating of neck tumours.

    PubMed

    Gross, E J; Cetas, T C; Stauffer, P R; Liu, R L; Lumori, M L

    1990-01-01

    An investigation of phased-array microwave systems (PAMS) for non-invasively inducing hyperthermia, primarily in neck lesions, has been done with implications for applications at other sites such as lung and pelvis. Our general approach was to combine numerical and analytical approaches with parallel experimental studies. In this paper we will concentrate only on the experimental aspects. The object, such as a homogeneous cylindrical phantom or a neck phantom, was encircled with several standard applicators driven by a single source, but with relative phase and amplitude control over each applicator. The relative phases of the applicators were adjusted by using an implanted monopole antenna connected to an HP network analyser. Power was applied and the specific absorption rate (SAR) was determined by using split phantoms and thermography or by measuring temperature transients dT/dt, recorded by implanted thermometer probes. We found that at 915 MHz for our applicators (SMA Co.) the centre of an 11 cm diameter muscle-like phantom heated to about 33% of the value at the surface in front of the applicator. Similarly, we were able to show significant SAR at the centre of realistically sized neck phantoms using four phased apertures of 915 MHz. Furthermore, substantial improvement was observed if the frequency was lowered to about 400 MHz. PMID:2324581

  13. Means for phase locking the outputs of a surface emitting laser diode array

    NASA Technical Reports Server (NTRS)

    Lesh, James R. (Inventor)

    1987-01-01

    An array of diode lasers, either a two-dimensional array of surface emitting lasers, or a linear array of stripe lasers, is phase locked by a diode laser through a hologram which focuses the output of the diode laser into a set of distinct, spatially separated beams, each one focused onto the back facet of a separate diode laser of the array. The outputs of the diode lasers thus form an emitted coherent beam out of the front of the array.

  14. Longitudinal-mode control in integrated semiconductor laser phased arrays by phase velocity matching

    NASA Technical Reports Server (NTRS)

    Kapon, E.; Margalit, S.; Yariv, A.; Katz, J.

    1984-01-01

    The spectrum of semiconductor-laser arrays with separate contacts is investigated. It is demonstrated that the individual laser currents can be selected such that the array operates in a single longitudinal mode, in contrast to the multimode nature of its individual constituents. Moreover, it is possible to tune the lasing frequency by varying the laser currents. Wavelength tuning range of about 50 A, with tuning rate of about 5 A per milliampere, is demonstrated. It is suggested that these spectral features, characteristic of lasers which are coupled in parallel, result from the strong frequency dependence of their spatial mode pattern near the phase-matching frequency of their coupled waveguides.

  15. Phased array beamforming and imaging in composite laminates using guided waves

    NASA Astrophysics Data System (ADS)

    Tian, Zhenhua; Leckey, Cara A. C.; Yu, Lingyu

    2016-04-01

    This paper presents the phased array beamforming and imaging using guided waves in anisotropic composite laminates. A generic phased array beamforming formula is presented, based on the classic delay-and-sum principle. The generic formula considers direction-dependent guided wave properties induced by the anisotropic material properties of composites. Moreover, the array beamforming and imaging are performed in frequency domain where the guided wave dispersion effect has been considered. The presented phased array method is implemented with a non-contact scanning laser Doppler vibrometer (SLDV) to detect multiple simulated defects at different locations in an anisotropic composite plate. The array is constructed of scan points in a small area rapidly scanned by the SLDV. Using the phased array method, multiple simulated defects at different locations are successfully detected. Our study shows that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures.

  16. Phased Array Beamforming and Imaging in Composite Laminates Using Guided Waves

    NASA Technical Reports Server (NTRS)

    Tian, Zhenhua; Leckey, Cara A. C.; Yu, Lingyu

    2016-01-01

    This paper presents the phased array beamforming and imaging using guided waves in anisotropic composite laminates. A generic phased array beamforming formula is presented, based on the classic delay-and-sum principle. The generic formula considers direction-dependent guided wave properties induced by the anisotropic material properties of composites. Moreover, the array beamforming and imaging are performed in frequency domain where the guided wave dispersion effect has been considered. The presented phased array method is implemented with a non-contact scanning laser Doppler vibrometer (SLDV) to detect multiple defects at different locations in an anisotropic composite plate. The array is constructed of scan points in a small area rapidly scanned by the SLDV. Using the phased array method, multiple defects at different locations are successfully detected. Our study shows that the guided wave phased array method is a potential effective method for rapid inspection of large composite structures.

  17. Acoustic transducer

    DOEpatents

    Drumheller, D.S.

    1997-12-30

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

  18. Acoustic transducer

    DOEpatents

    Drumheller, Douglas S.

    1997-01-01

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

  19. Matrix phased arrays for the inspection of CFRP-components

    SciTech Connect

    Kreutzbruck, M.; Brackrock, D.; Brekow, G.; Montag, H.-J.; Boehm, R.; Illerhaus, B.

    2014-02-18

    Lightweight components are increasingly used in different industrial sectors such as transportation, energy generation and automotive. This growing field includes different types of CFRP-structures, hybrid materials and glued components showing - compared to their pure metallic counterparts- a significant more complicated structure in terms of internal interfaces and anisotropy of material parameters. In this work we present the use of matrix phased array to increase the amount of obtained information to enhance the inspection quality. We used different types of carbon materials such as 6 mm thick uni- and bidirectional prepreg specimens containing impact damages. The latter were introduced with different energy levels ranging from 1.3 to 7.2 J. By scanning a 2.25 MHz matrix array with 6 × 10 elements above the prepreg surface and using different angels of incidence a complete 3D-image was generated which allows the detection of defects as small as 1mm in a depth of 4 mm. A comparison with conventional approaches show that the signal-to-noise ratio can be highly increased. This enables us to visualize the region of damage within the impact zone, clearly showing the cone-like damage distribution along increasing material depth. The detection quality allows the estimation of the opening angles of the cone shaped damage, which can be used for further evaluation and quantitation of energy dependent impact damages.

  20. Evolutionary Design of a Phased Array Antenna Element

    NASA Technical Reports Server (NTRS)

    Globus, Al; Linden, Derek; Lohn, Jason

    2006-01-01

    We present an evolved S-band phased array antenna element design that meets the requirements of NASA's TDRS-C communications satellite scheduled for launch early next decade. The original specification called for two types of elements, one for receive only and one for transmit/receive. We were able to evolve a single element design that meets both specifications thereby simplifying the antenna and reducing testing and integration costs. The highest performance antenna found using a genetic algorithm and stochastic hill-climbing has been fabricated and tested. Laboratory results are largely consistent with simulation. Researchers have been investigating evolutionary antenna design and optimization since the early 1990s, and the field has grown in recent years its computer speed has increased and electromagnetic simulators have improved. Many antenna types have been investigated, including wire antennas, antenna arrays and quadrifilar helical antennas. In particular, our laboratory evolved a wire antenna design for NASA's Space Technology 5 (ST5) spacecraft. This antenna has been fabricated, tested, and is scheduled for launch on the three spacecraft in 2006.

  1. Matrix phased arrays for the inspection of CFRP-components

    NASA Astrophysics Data System (ADS)

    Kreutzbruck, M.; Brackrock, D.; Brekow, G.; Montag, H.-J.; Boehm, R.; Illerhaus, B.

    2014-02-01

    Lightweight components are increasingly used in different industrial sectors such as transportation, energy generation and automotive. This growing field includes different types of CFRP-structures, hybrid materials and glued components showing - compared to their pure metallic counterparts- a significant more complicated structure in terms of internal interfaces and anisotropy of material parameters. In this work we present the use of matrix phased array to increase the amount of obtained information to enhance the inspection quality. We used different types of carbon materials such as 6 mm thick uni- and bidirectional prepreg specimens containing impact damages. The latter were introduced with different energy levels ranging from 1.3 to 7.2 J. By scanning a 2.25 MHz matrix array with 6 × 10 elements above the prepreg surface and using different angels of incidence a complete 3D-image was generated which allows the detection of defects as small as 1mm in a depth of 4 mm. A comparison with conventional approaches show that the signal-to-noise ratio can be highly increased. This enables us to visualize the region of damage within the impact zone, clearly showing the cone-like damage distribution along increasing material depth. The detection quality allows the estimation of the opening angles of the cone shaped damage, which can be used for further evaluation and quantitation of energy dependent impact damages.

  2. Theory of metascreen-based acoustic passive phased array

    NASA Astrophysics Data System (ADS)

    Li, Yong; Qi, Shuibao; Badreddine Assouar, M.

    2016-04-01

    The metascreen-based acoustic passive phased array provides a new degree of freedom for manipulating acoustic waves due to their fascinating properties, such as a fully shifting phase, keeping impedance matching, and holding subwavelength spatial resolution. We develop acoustic theories to analyze the transmission/reflection spectra and the refracted pressure fields of a metascreen composed of elements with four Helmholtz resonators (HRs) in series and a straight pipe. We find that these properties are also valid under oblique incidence with large angles, with the underlying physics stemming from the hybrid resonances between the HRs and the straight pipe. By imposing the desired phase profiles, the refracted fields can be tailored in an anomalous yet controllable manner. In particular, two types of negative refraction are exhibited, based on two distinct mechanisms: one is formed from classical diffraction theory and the other is dominated by the periodicity of the metascreen. Positive (normal) and negative refractions can be converted by simply changing the incident angle, with the coexistence of two types of refraction in a certain range of incident angles.

  3. Hyperthermia and inhomogeneous tissue effects using an Annular Phased Array

    SciTech Connect

    Turner, P.F.

    1984-08-01

    A regional hyperthermia Annular Phased Array (APA) applicator is described, and examples of its various heating patterns, obtained by scanning the electric fields with a small E-field sensor, are illustrated. Also shown are the effects of different frequencies of an elliptical phantom cylinder having a 1-cm-thick artificial fat wall and the general dimensions of the human trunk. These studies show the APA's ability to achieve uniform heating at lower frequencies (below 70 MHz) or to focus central heating at moderately higher frequencies (above 70 MHz). The influence of human anatomical contours in altering heating patterns is discussed using results obtained with a female mannequin having a thin latex shell filled with tissue-equivalent phantom. Field perturbations caused by internally embedded low-dielectric structures are presented, showing the localized effects of small objects whose surfaces are perpendicular to the electric field.

  4. Time-delayed directional beam phased array antenna

    DOEpatents

    Fund, Douglas Eugene; Cable, John William; Cecil, Tony Myron

    2004-10-19

    An antenna comprising a phased array of quadrifilar helix or other multifilar antenna elements and a time-delaying feed network adapted to feed the elements. The feed network can employ a plurality of coaxial cables that physically bridge a microstrip feed circuitry to feed power signals to the elements. The cables provide an incremental time delay which is related to their physical lengths, such that replacing cables having a first set of lengths with cables having a second set of lengths functions to change the time delay and shift or steer the antenna's main beam. Alternatively, the coaxial cables may be replaced with a programmable signal processor unit adapted to introduce the time delay using signal processing techniques applied to the power signals.

  5. Quantum phase transition of light in the resonator array

    NASA Astrophysics Data System (ADS)

    Wu, Chun-Wang; Gao, Ming; Deng, Zhi-Jiao; Dai, Hong-Yi; Chen, Ping-Xing; Li, Cheng-Zu; Quantum Computation Group of NUDT Team

    2015-03-01

    We give a concrete experimental scheme for engineering the insulator-superfluid transition of light in a one-dimensional (1-D) array of coupled superconducting stripline resonators. In our proposed architecture, the on-site interaction and the photon hopping rate can be tuned independently by adjusting the transition frequencies of the charge qubits inside the resonators and at the resonator junctions, respectively, which permits us to systematically study the quantum phase transition of light in a complete parameter space. By combining the techniques of photon-number-dependent qubit transition and fast read-out of the qubit state using a separate low-Q resonator mode, the statistical property of the excitations in each resonator can be obtained with a high efficiency. An analysis of the various decoherence sources and disorders shows that our scheme can serve as a guide to coming experiments involving a small number of coupled resonators.

  6. Phased-Array Measurements of Single Flow Hot Jets

    NASA Technical Reports Server (NTRS)

    Bridges, James; Lee, Sang Soo

    2005-01-01

    A 16 microphone phased-array system has been successfully applied to measure jet noise source distributions. In this study, a round convergent nozzle was tested at various hot and cold flow conditions: acoustic Mach numbers are between 0.35 and 1.6 and static temperature ratios are varied from cold to 2.7. The classical beamforming method was applied on narrowband frequencies. From the measured source distributions locations of peak strength were tracked and found to be very consistent between adjacent narrowband frequencies. In low speed heated and unheated jets, the peak source locations vary smoothly from the nozzle exit to downstream as the frequency is decreased. When the static temperature ratio was kept constant, the peak source position moved downstream with increasing acoustic Mach number for the Strouhal numbers smaller than about 1.5. It was also noted that the peak source locations of low frequencies occur farther downstream than the end of potential core.

  7. Estimate of the attenuation coefficient using a clinical array transducer for the detection of cervical ripening in human pregnancy.

    PubMed

    Labyed, Yassin; Bigelow, Timothy A; McFarlin, Barbara L

    2011-01-01

    Premature delivery is the leading cause of infant mortality in the United States. Currently, premature delivery cannot be prevented and new treatments are difficult to develop due to the inability to diagnose symptoms prior to uterine contractions. Cervical ripening is a long period that precedes the active phase of uterine contractions and cervical dilation. The changes in the microstructure of the cervix during cervical ripening suggest that the ultrasonic attenuation should decrease. The objective of this study is to use the reference phantom algorithm to estimate the ultrasonic attenuation in the cervix of pregnant human patients. Prior to applying the algorithm to in vivo human data, two homogeneous phantoms with known attenuation coefficients were used to validate the algorithm and to find the length and the width of the region of interest (ROI) that achieves the smallest error in the attenuation coefficient estimates. In the phantom data, we found that the errors in the attenuation coefficients estimates are less than 12% for ROIs that contain 40 wavelengths or more axially and 30 echo lines or more laterally. The reference phantom algorithm was then used to obtain attenuation maps of the echoes from two human pregnant cervices at different gestational ages. It was observed that the mean of the attenuation coefficient estimates in the cervix of the patient at a more advanced gestational age is smaller than the mean of the attenuation coefficient estimates in the cervix of the patient at an earlier gestational age which suggests that ultrasonic attenuation decreases with increasing gestational age. We also observed a large variance between the attenuation coefficient estimates in the different regions of the cervix due to the natural variation in tissue micro-structures across the cervix. The preliminary results indicate that the algorithm could potentially provide an important diagnostic tool for diagnosing the risk of premature delivery. PMID:20570308

  8. Ultrasonic transducer

    SciTech Connect

    Taylor, Steven C.; Kraft, Nancy C.

    2007-03-13

    An ultrasonic transducer having an effective center frequency of about 42 MHz; a bandwidth of greater than 85% at 6 dB; a spherical focus of at least 0.5 inches in water; an F4 lens; a resolution sufficient to be able to detect and separate a 0.005 inch flat-bottomed hole at 0.005 inches below surface; and a beam size of approximately 0.006–0.008 inches measured off a 11/2 mm ball in water at the transducer's focal point.

  9. Design and experimental evaluation of an intracavitary ultrasound phased array system for hyperthermia.

    PubMed

    Buchanan, M T; Hynynen, K

    1994-12-01

    For evaluating the feasibility of treating prostate cancer, a 64-element linear ultrasound phased array applicator for intracavitary hyperthermia was designed and constructed. A 64-channel ultrasound driving system including amplifiers, phase shifters, and RF power meters was also developed to drive the array. The design of the array and driving equipment are presented, as are the results of acoustical field measurements and in vitro perfused phantom studies performed with the array. Several techniques for heating realistically sized tumor volumes were also investigated, including single focus scanning and two techniques for producing multiple stationary foci. The results show that the operation of the array correlated closely with the theoretical model. When producing a single stationary focus, the array was able to increase tissue temperature by 12 degrees C in vitro in perfused phantom. With some minor improvements in array design, intracavitary phased arrays could be evaluated in a clinical environment. PMID:7851919

  10. Phase-locked laser array having a non-uniform spacing between lasing regions

    NASA Technical Reports Server (NTRS)

    Ackley, Donald E. (Inventor)

    1986-01-01

    A phase-locked semiconductor array wherein the lasing regions of the array are spaced an effective distance apart such that the modes of oscillation of the different lasing regions are phase-locked to one another. The center-to-center spacing between the lasing regions is non-uniform. This variation in spacing perturbs the preferred 180.degree. phase difference between adjacent lasing regions thereby providing an increased yield of arrays exhibiting a single-lobed, far-field radiation pattern.

  11. Development of ultrasonic phased array systems for applications in tube and pipe inspection

    NASA Astrophysics Data System (ADS)

    Guo, Yanming; Yuan, Qingshan; Sun, Zhigang; Logan, Kevin; Lam, Clive

    2012-05-01

    This paper reports the development of ultrasonic phased array systems used for tubular inspection. First the design of a linear phased array is discussed with considerations of both theoretically and practically important factors. Then systems utilizing the linear phased array are introduced for different applications. To evaluate the system performance, tests were performed on flat bottom holes and artificial notches, including notches in longitudinal, transverse, and oblique orientations made according to API specifications. Test results have been presented.

  12. A Study of Phased Array Antennas for NASA's Deep Space Network

    NASA Technical Reports Server (NTRS)

    Jamnejad, Vahraz; Huang, John; Cesarone, Robert J.

    2001-01-01

    In this paper we briefly discuss various options but focus on the feasibility of the phased arrays as a viable option for this application. Of particular concern and consideration will be the cost, reliability, and performance compared to the present 70-meter antenna system, particularly the gain/noise temperature levels in the receive mode. Many alternative phased arrays including planar horizontal arrays, hybrid mechanically/electronically steered arrays, phased array of mechanically steered reflectors, multi-faceted planar arrays, phased array-fed lens antennas, and planar reflect-arrays are compared and their viability is assessed. Although they have many advantages including higher reliability, near-instantaneous beam switching or steering capability, the cost of such arrays is presently prohibitive and it is concluded that the only viable array options at the present are the arrays of a few or many small reflectors. The active planar phased arrays, however, may become feasible options in the next decade and can be considered for deployment in smaller configurations as supplementary options.

  13. Phased Array Technology with Phase and Amplitude Controlled Magnetron for Microwave Power Transmission

    NASA Astrophysics Data System (ADS)

    Shinohara, N.; Matsumoto, H.

    2004-12-01

    We need a microwave power transmitter with light weight and high DC-RF conversion efficiency for an economical SSPS (Space Solar Power System). We need a several g/W for a microwave power transmission (MPT) system with a phased array with 0.0001 degree of beam control accuracy (=tan-1 (100m/36,000km)) and over 80 % of DC-RF conversion efficiency when the weight of the 1GW-class SPS is below a several thousand ton - a several tens of thousand ton. We focus a microwave tube, especially magnetron by economical reason and by the amount of mass-production because it is commonly used for microwave oven in the world. At first, we have developed a phase controlled magnetron (PCM) with different technologies from what Dr. Brown developed. Next we have developed a phase and amplitude controlled magnetron (PACM). For the PACM, we add a feedback to magnetic field of the PCM with an external coil to control and stabilize amplitude of the microwave. We succeed to develop the PACM with below 10-6 of frequency stability and within 1 degree of an error in phase and within 1% of amplitude. We can control a phase and amplitude of the PACM and we have developed a phased array the PCMs. With the PCM technology, we have developed a small light weight MPT transmitter COMET (Compact Microwave Energy Transmitter) with consideration of heat radiation for space use and with consideration of mobility to space.

  14. Phased-array grating compression for high-energy chirped pulse amplification lasers.

    PubMed

    Cotel, A; Castaing, M; Pichon, P; Le Blanc, C

    2007-03-01

    The development of phased-array grating compressor is a crucial issue for high-energy, ultra-short pulse petawatt-class lasers. We present a theoretical and experimental analysis of two-grating phasing in a broadband pulse mosaic compressor. The phase defaults induced by misaligned gratings are studied. Monochromatic grating phasing is experimentally achieved with an interferometric technique and pulse compression is demonstrated with a two-phased-array grating system. PMID:19532511

  15. Experiments in ultrasonic flaw detection using a MEMS transducer

    NASA Astrophysics Data System (ADS)

    Jain, Akash; Greve, David W.; Oppenheim, Irving J.

    2003-08-01

    In earlier work we developed a MEMS phased array transducer, fabricated in the MUMPs process, and we reported on initial experimental studies in which the device was affixed into contact with solids. We demonstrated the successful detection of signals from a conventional ultrasonic source, and the successful localization of the source in an off-axis geometry using phased array signal processing. We now describe the predicted transmission and coupling characteristics for such devices in contact with solids, demonstrating reasonable agreement with experimental behavior. We then describe the results of flaw detection experiments, as well as results for fluid-coupled detectors.

  16. Electronically controlled optical beam-steering by an active phased array of metallic nanoantennas.

    PubMed

    DeRose, C T; Kekatpure, R D; Trotter, D C; Starbuck, A; Wendt, J R; Yaacobi, A; Watts, M R; Chettiar, U; Engheta, N; Davids, P S

    2013-02-25

    An optical phased array of nanoantenna fabricated in a CMOS compatible silicon photonics process is presented. The optical phased array is fed by low loss silicon waveguides with integrated ohmic thermo-optic phase shifters capable of 2π phase shift with ∼ 15 mW of applied electrical power. By controlling the electrical power to the individual integrated phase shifters fixed wavelength steering of the beam emitted normal to the surface of the wafer of 8° is demonstrated for 1 × 8 phased arrays with periods of both 6 and 9 μm. PMID:23482053

  17. PARAS program: Phased array radio astronomy from space

    NASA Technical Reports Server (NTRS)

    Jakubowski, Antoni K.; Haynes, David A.; Nuss, Ken; Hoffmann, Chris; Madden, Michael; Dungan, Michael

    1992-01-01

    An orbiting radio telescope is proposed which, when operated in a Very Long Baseline Interferometry (VLBLI) scheme, would allow higher (than currently available) angular resolution and dynamic range in the maps, and the ability of observing rapidly changing astronomical sources. Using a passive phases array technology, the proposed design consists of 656 hexagonal modules forming a 150 meter diameter dish. Each observatory module is largely autonomous, having its own photovoltaic power supply and low-noise receiver and processor for phase shifting. The signals received by the modules are channeled via fiber optics to the central control computer in the central bus module. After processing and multiplexing, the data is transmitted to telemetry stations on the ground. The truss frame supporting each observatory pane is a hybrid structure consisting of a bottom graphite/epoxy tubular triangle and rigidized inflatable Kevlar tubes connecting the top observatory panel and bottom triangle. Attitude control and stationkeeping functions are performed by a system of momentum wheels in the bus and four propulsion modules located at the compass points on the periphery of the observatory dish. Each propulsion module has four monopropellant thrusters and six hydrazine arcjets, the latter supported by a nuclear reactor. The total mass of the spacecraft is 22,060 kg.

  18. Development of phased array ultrasonic testing in lieu of radiography for testing complete joint penetration (CJP) welds

    NASA Astrophysics Data System (ADS)

    Haldipur, P.; Boone, Shane D.

    2014-04-01

    The past decade has seen new, emerging innovation of Ultrasonic Testing (UT). Specifically, multiple manufacturers have produced Phased Array Ultrasonic Testing (PAUT) systems. The PAUT systems embed a matrix of multiple (some up to 128) single transducers into one probe used for scanning elastic materials. Simultaneously exciting multiple transducers offers distinct advantages; depending on the sequencing of transducer excitation, the ultrasonic beam could be steered within the material and multiple beams help develop extra dimensional data to assist with visualization of possible flaws including the discontinuity size, shape and location. Unfortunately, there has not been broad acceptance of PAUT in the bridge fabrication industry because it is currently not a recognized inspection technology in AWS D1.5. One situation in which the technology would excel would be inspection of Complete Joint Penetration (CJP) butt welds. Currently, AWS D1.5 required CJP welds subjected to tensile or reversal stresses only be inspected by Radiographic Testing (RT). However, discontinuities normally seen by RT can also be seen with PAUT. Until specification language is adopted into D1.5, there will continue to be hesitancy to use PAUT for the inspection of CJP butt welds. Developmental work must first be performed to develop the acceptance criteria and the specification language. The developmental work from the inspections carried out on butt-weld specimens and transition butt-weld specimens are presented in this paper. Specific scan plans were developed using the ES-Beam simulation software for each of the test specimens. In depth analysis of PAUT data obtained to determine exact location and sizing information of the defects was performed. The results also present the comparison of results from PAUT to those obtained using conventional UT and radiography.

  19. Finite element simulation of single ultrasonic transducer with segmented electrodes to adjust the directional characteristic

    NASA Astrophysics Data System (ADS)

    Unverzagt, Carsten; Henning, Bernd

    2012-05-01

    For many applications like level measurement and industry robotics it is of advantage if the directional characteristic of an ultrasonic transducer is changeable or adaptable for the improvement of spatial resolution. Often this goal is reached with the use of ultrasonic transducer arrays, which elements are driven with phase shifted excitation signals. One disadvantage of these solutions is the great effort for building such an array and the multi-channel sensor electronics. In this contribution the directional characteristic of a single air transducer with segmented electrodes is analyzed. Therefore a variable script based finite element model is used to discover the influence of different electrode configurations on the directional characteristic of a single piezoceramic transducer. Especially the influence on the angle of beam and the near field length are evaluated. The used variable model permits an optimization of the configuration with regards to the mentioned criteria. The findings will be used for the development of a level measurement system for bulk solids.

  20. A dual-piston ring-driven X-spring transducer

    NASA Astrophysics Data System (ADS)

    Butler, Alexander L.; Butler, John L.; Pendleton, Robert L.; Ead, Richard M.

    2001-05-01

    Tonpilz transducers generally consist of a stack of piezoelectric material sandwiched between a single piston and an inertial tail mass or between two pistons. The result is a transducer with a large length-to-diameter ratio. The X-spring transducer design, based on U.S. Patent 4845688, allows a means for a shorter transducer length through an orthogonal piezoelectric drive system coupled to the pistons by lever arms. We present here a low-frequency, dual-piston piezoelectric ceramic ring driven version with a length of only 10 in. and a diameter of 19 in. Both single-element and two-element array results are presented. The measured response is shown to be in agreement with the finite-element model with a smooth, wideband 300- to 550-Hz response for this dual-piston, ring-driven X-spring transducer. [Work supported by a Phase II SBIR, through NUWC, Newport, RI 02841.

  1. Phase dynamics of high radiance fiber laser arrays with active phase control

    NASA Astrophysics Data System (ADS)

    Bochove, Erik; Neschke, Brendan; Nair, Niketh; Delgado, Paul; Braiman, Yehuda

    2015-03-01

    The existing model of the LOCSET technique for the active phase synchronization of fiber laser arrays (T. Shay, Opt. Express, 2006) is extended to include relevant physical properties of the system, such as inherent optical path differences (OPD), line-width and group velocity dispersion (GVD), and we also include phase "jitter" of the master oscillator's output in the model, which in experiments is implemented to induce spectral broadening for suppression of nonlinear frequency conversion. Linearization of the phase error signal, which incorrectly predicts convergence to a synchronous equilibrium state, is not performed. Instead, the closed-loop control dynamics are shown to be described by differential equations of Kuramoto type when phase corrector response dynamics are negligible. Linear stability analysis indicates that there is always one and no more than one dynamically stable state. The latter is shown to be normally synchronous, except when strong "jitter" is applied. A Liapounov function is found as subject to the validity of certain symmetry conditions.

  2. Rate equations analysis of phase-locked semiconductor laser arrays under steady state conditions

    NASA Technical Reports Server (NTRS)

    Katz, J.; Kapon, E.; Margalit, S.; Yariv, A.

    1984-01-01

    Rate equations analysis of phase-locked semiconductor laser arrays has been carried out. It was found that for given (laser) current densities, the photon density distribution in the array elements is that particular one which maximizes the total photon density. The results of this analysis were then combined with the waveguide properties of the laser array waveguide, yielding a basic model of phase-locked diode laser arrays. This model explains the effects of the variation of the current combination through the array elements on its mode structure that were observed recently.

  3. A self-cohering technique for linear arrays using the Phase Gradient Autofocus Algorithm

    SciTech Connect

    Wahl, D.E.

    1991-02-01

    A towed linear hydrophone array is subject to snakelike bending. If the array were processed as if it were truly linear, poor array gain coupled with a degraded source bearing estimate would result. The signal phase errors produced by sensor position uncertainty in passive sonar arrays are similar to those observed in Synthetic Aperture Radar (SAR) imagery. The Phase Gradient Autofocus (PGA) Algorithm has been shown to be a robust and effective method used to extract degrading phase errors prevalent in SAR imagery. This report shows that with slight modifications, the PGA algorithm can be applied to correct phase errors resulting from sensor position uncertainty introduced into linear-passive arrays. The results of the technique applied to simulated linear array data is also presented. 9 refs., 8 figs.

  4. Phased array feed design technology for Large Aperture Microwave Radiometer (LAMR) Earth observations

    NASA Technical Reports Server (NTRS)

    Schuman, H. K.

    1992-01-01

    An assessment of the potential and limitations of phased array antennas in space-based geophysical precision radiometry is described. Mathematical models exhibiting the dependence of system and scene temperatures and system sensitivity on phased array antenna parameters and components such as phase shifters and low noise amplifiers (LNA) are developed. Emphasis is given to minimum noise temperature designs wherein the LNA's are located at the array level, one per element or subarray. Two types of combiners are considered: array lenses (space feeds) and corporate networks. The result of a survey of suitable components and devices is described. The data obtained from that survey are used in conjunction with the mathematical models to yield an assessment of effective array antenna noise temperature for representative geostationary and low Earth orbit systems. Practical methods of calibrating a space-based, phased array radiometer are briefly addressed as well.

  5. Impact: a low cost, reconfigurable, digital beamforming common module building block for next generation phased arrays

    NASA Astrophysics Data System (ADS)

    Paulsen, Lee; Hoffmann, Ted; Fulton, Caleb; Yeary, Mark; Saunders, Austin; Thompson, Dan; Chen, Bill; Guo, Alex; Murmann, Boris

    2015-05-01

    Phased array systems offer numerous advantages to the modern warfighter in multiple application spaces, including Radar, Electronic Warfare, Signals Intelligence, and Communications. However, a lack of commonality in the underlying technology base for DoD Phased Arrays has led to static systems with long development cycles, slow technology refreshes in response to emerging threats, and expensive, application-specific sub-components. The IMPACT module (Integrated Multi-use Phased Array Common Tile) is a multi-channel, reconfigurable, cost-effective beamformer that provides a common building block for multiple, disparate array applications.

  6. Pressure transducer

    DOEpatents

    Anderson, Thomas T.; Roop, Conard J.; Schmidt, Kenneth J.; Gunchin, Elmer R.

    1989-01-01

    A pressure transducer suitable for use in high temperature environments includes two pairs of induction coils, each pair being bifilarly wound together, and each pair of coils connected as opposite arms of a four arm circuit; an electrically conductive target moveably positioned between the coil pairs and connected to a diaphragm such that deflection of the diaphragm causes axial movement of the target and an unbalance in the bridge output.

  7. PRESSURE TRANSDUCER

    DOEpatents

    Sander, H.H.

    1959-10-01

    A pressure or mechanical force transducer particularly adaptable to miniature telemetering systems is described. Basically the device consists of a transistor located within a magnetic field adapted to change in response to mechanical force. The conduction characteristics of the transistor in turn vary proportionally with changes in the magnetic flux across the transistor such that the output (either frequency of amplitude) of the transistor circuit is proportional to mechanical force or pressure.

  8. Pressure transducer

    DOEpatents

    Anderson, T.T.; Roop, C.J.; Schmidt, K.J.; Gunchin, E.R.

    1987-02-13

    A pressure transducer suitable for use in high temperature environments includes two pairs of induction coils, each pair being bifilarly wound together, and each pair of coils connected as opposite arms of a four arm circuit; an electrically conductive target moveably positioned between the coil pairs and connected to a diaphragm such that deflection of the diaphragm causes axial movement of the target and an unbalance in the bridge output. 7 figs.

  9. Electrowetting lenses for compensating phase and curvature distortion in arrayed laser systems.

    PubMed

    Niederriter, Robert D; Watson, Alexander M; Zahreddine, Ramzi N; Cogswell, Carol J; Cormack, Robert H; Bright, Victor M; Gopinath, Juliet T

    2013-05-10

    We have demonstrated a one-dimensional array of individually addressable electrowetting tunable liquid lenses that compensate for more than one wave of phase distortion across a wavefront. We report a scheme for piston control using tunable liquid lens arrays in volume-bound cavities that alter the optical path length without affecting the wavefront curvature. Liquid lens arrays with separately tunable focus or phase control hold promise for laser communication systems and adaptive optics. PMID:23669829

  10. Matrix phased array (MPA) imaging technology for resistance spot welds

    SciTech Connect

    Na, Jeong K.; Gleeson, Sean T.

    2014-02-18

    A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed.

  11. Matrix phased array (MPA) imaging technology for resistance spot welds

    NASA Astrophysics Data System (ADS)

    Na, Jeong K.; Gleeson, Sean T.

    2014-02-01

    A three-dimensional MPA probe has been incorporated with a high speed phased array electronic board to visualize nugget images of resistance spot welds. The primary application area of this battery operated portable MPA ultrasonic imaging system is in the automotive industry which a conventional destructive testing process is commonly adopted to check the quality of resistance spot welds in auto bodies. Considering an average of five-thousand spot welds in a medium size passenger vehicle, the amount of time and effort given to popping the welds and measuring nugget size are immeasurable in addition to the millions of dollars' worth of scrap metals recycled per plant per year. This wasteful labor intensive destructive testing process has become less reliable as auto body sheet metal has transitioned from thick and heavy mild steels to thin and light high strength steels. Consequently, the necessity of developing a non-destructive inspection methodology has become inevitable. In this paper, the fundamental aspects of the current 3-D probe design, data acquisition algorithms, and weld nugget imaging process are discussed.

  12. Evolutionary Adaptive Discovery of Phased Array Sensor Signal Identification

    SciTech Connect

    Timothy R. McJunkin; Milos Manic

    2011-05-01

    Tomography, used to create images of the internal properties and features of an object, from phased array ultasonics is improved through many sophisiticated methonds of post processing of data. One approach used to improve tomographic results is to prescribe the collection of more data, from different points of few so that data fusion might have a richer data set to work from. This approach can lead to rapid increase in the data needed to be stored and processed. It also does not necessarily lead to have the needed data. This article describes a novel approach to utilizing the data aquired as a basis for adapting the sensors focusing parameters to locate more precisely the features in the material: specifically, two evolutionary methods of autofocusing on a returned signal are coupled with the derivations of the forumulas for spatially locating the feature are given. Test results of the two novel methods of evolutionary based focusing (EBF) illustrate the improved signal strength and correction of the position of feature using the optimized focal timing parameters, called Focused Delay Identification (FoDI).

  13. Group and phase delay sensing for cophasing large optical arrays

    NASA Astrophysics Data System (ADS)

    Mourard, D.; Dali Ali, W.; Meilland, A.; Tarmoul, N.; Patru, F.; Clausse, J. M.; Girard, P.; Hénault, F.; Marcotto, A.; Mauclert, N.

    2014-12-01

    The next generation of optical interferometers will provide high-resolution imaging of celestial objects by using either the aperture synthesis technique or the direct imaging principle. To determine the technical requirements, we have developed an interferometric test bench, called SIRIUS. To preserve the quality of the image, fast corrections of the optical path differences within a fraction of a wavelength have to be applied: this is the cophasing of the array, whereas making it coherent aims at stabilizing the optical path differences within a fraction of the coherence length. In the SIRIUS test bench, coherence and cophasing are achieved by fibred delay lines. Air delay lines are also used for the raw delay equalization. We present an original implementation of a piston sensor, called chromatic phase diversity, which is adaptable to any interferometer, whatever the configuration of the entrance pupil and the number of sub-pupils and whatever the interferometric combiner. Our method is based on the dispersed fringes principle and uses a derived version of the dispersed speckles method. The numerical simulation shows the performance of the method in terms of cophasing, accuracy and limiting magnitude. Experimental tests have been carried out both with optical turbulence and without. They show good results in both cases, despite some instrument-related limitations that can be eliminated. We show that our method is able to handle an amplitude of correction of ±11(λ/2) with an accuracy of ˜λ/30 over many minutes.

  14. Low-Cost Phased Array Antenna for Sounding Rockets, Missiles, and Expendable Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Mullinix, Daniel; Hall, Kenneth; Smith, Bruce; Corbin, Brian

    2012-01-01

    A low-cost beamformer phased array antenna has been developed for expendable launch vehicles, rockets, and missiles. It utilizes a conformal array antenna of ring or individual radiators (design varies depending on application) that is designed to be fed by the recently developed hybrid electrical/mechanical (vendor-supplied) phased array beamformer. The combination of these new array antennas and the hybrid beamformer results in a conformal phased array antenna that has significantly higher gain than traditional omni antennas, and costs an order of magnitude or more less than traditional phased array designs. Existing omnidirectional antennas for sounding rockets, missiles, and expendable launch vehicles (ELVs) do not have sufficient gain to support the required communication data rates via the space network. Missiles and smaller ELVs are often stabilized in flight by a fast (i.e. 4 Hz) roll rate. This fast roll rate, combined with vehicle attitude changes, greatly increases the complexity of the high-gain antenna beam-tracking problem. Phased arrays for larger ELVs with roll control are prohibitively expensive. Prior techniques involved a traditional fully electronic phased array solution, combined with highly complex and very fast inertial measurement unit phased array beamformers. The functional operation of this phased array is substantially different from traditional phased arrays in that it uses a hybrid electrical/mechanical beamformer that creates the relative time delays for steering the antenna beam via a small physical movement of variable delay lines. This movement is controlled via an innovative antenna control unit that accesses an internal measurement unit for vehicle attitude information, computes a beam-pointing angle to the target, then points the beam via a stepper motor controller. The stepper motor on the beamformer controls the beamformer variable delay lines that apply the appropriate time delays to the individual array elements to properly

  15. Research on tunable phase shift induced by piezoelectric transducer in linearly chirped fiber Bragg grating with the V-I transmission matrix formalism

    NASA Astrophysics Data System (ADS)

    Wu, Liangying; Pei, Li; Liu, Chao; Wang, Jianshuai

    2016-05-01

    In this study, the V-I transmission matrix (V-I TM) is proposed to analyze the tunable single phase shift (SPS) and multiple phase shifts (MPS) inserted in a linearly chirped fiber Bragg grating (LCFBG). According to the simulation results, the peaks appear on the transmission spectrum, when the phase shifts are induced in the LCFBG. With the increase of the phase shift, the center wavelength of the peak moves toward long wavelength region. A remarkable degree of bilateral symmetry can be found as characteristic of the depth of peaks. The maximum depth caused by inserted π-shift is the symmetric axis. Moreover, when MPS are inserted simultaneously, the appeared peaks are independent and the variation tendency of each peak is the same with that caused by SPS. The experiment of phase shift induced by a piezoelectric transducer (PZT) verifies the correctness of the simulation, and a narrow bandwidth of 0.028 nm is acquired.

  16. Electro-optical processing of phased array data

    NASA Technical Reports Server (NTRS)

    Casasent, D.

    1973-01-01

    An on-line spatial light modulator for application as the input transducer for a real-time optical data processing system is described. The use of such a device in the analysis and processing of radar data in real time is reported. An interface from the optical processor to a control digital computer was designed, constructed, and tested. The input transducer, optical system, and computer interface have been operated in real time with real time radar data with the input data returns recorded on the input crystal, processed by the optical system, and the output plane pattern digitized, thresholded, and outputted to a display and storage in the computer memory. The correlation of theoretical and experimental results is discussed.

  17. An Ultra-Wideband Millimeter-Wave Phased Array

    NASA Technical Reports Server (NTRS)

    Novak, Markus H.; Miranda, Felix A.; Volakis, John L.

    2016-01-01

    Wideband millimeter-wave arrays are of increasing importance due to their growing use in high data rate systems, including 5G communication networks. In this paper, we present a new class of ultra-wideband millimeter wave arrays that operate from nearly 20 GHz to 90 GHz. The array is based on tightly coupled dipoles. Feeding designs and fabrication challenges are presented, and a method for suppressing feed resonances is provided.

  18. Fully Printed, Flexible, Phased Array Antenna for Lunar Surface Communication

    NASA Technical Reports Server (NTRS)

    Subbaraman, Harish; Hen, Ray T.; Lu, Xuejun; Chen, Maggie Yihong

    2013-01-01

    NASAs future exploration missions focus on the manned exploration of the Moon, Mars, and beyond, which will rely heavily on the development of a reliable communications infrastructure from planetary surface-to-surface, surface-to-orbit, and back to Earth. Flexible antennas are highly desired in many scenarios. Active phased array antennas (active PAAs) with distributed control and processing electronics at the surface of an antenna aperture offer numerous advantages for radar communications. Large-area active PAAs on flexible substrates are of particular interest in NASA s space radars due to their efficient inflatable package that can be rolled up during transportation and deployed in space. Such an inflatable package significantly reduces stowage volume and mass. Because of these performance and packaging advantages, large-area inflatable active PAAs are highly desired in NASA s surface-to-orbit and surface-to-relay communications. To address the issues of flexible electronics, a room-temperature printing process of active phased-array antennas on a flexible Kapton substrate was developed. Field effect transistors (FETs) based on carbon nanotubes (CNTs), with many unique physical properties, were successfully proved feasible for the PAA system. This innovation is a new type of fully inkjet-printable, two-dimensional, high-frequency PAA on a flexible substrate at room temperature. The designed electronic circuit components, such as the FET switches in the phase shifter, metal interconnection lines, microstrip transmission lines, etc., are all printed using a special inkjet printer. Using the developed technology, entire 1x4, 2x2, and 4x4 PAA systems were developed, packaged, and demonstrated at 5.3 GHz. Several key solutions are addressed in this work to solve the fabrication issues. The source/drain contact is developed using droplets of silver ink printed on the source/drain areas prior to applying CNT thin-film. The wet silver ink droplets allow the silver to

  19. Power Spectrum of Uplink Array Signals with Random Phase and Delay Errors

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor A.

    2011-01-01

    Link Array signals emanating from different antennas must be compensated for Doppler and delay in order to achieve the N(sup 2) array gain predicted by theory. However compensation is never perfect, leaving residual errors that cause losses in array gain and degradation in signal quality. Here we develop a mathematical model for Uplink Array signals in the presence of phase and delay errors, similar to well-known multipath analyses but with features unique to this problem. The resulting losses and distortions are described, and the power spectral density of the array signal derived first conditioned on a given error vector, then averaged over distributions deemed suitable for Uplink Array applications. The impact of phase and delay errors on array gain and signal distortion are addressed, and the maximum data throughput is quantified in terms of the assumed error statistics.

  20. Pattern phase diagram for two-dimensional arrays of coupled limit-cycle oscillators.

    PubMed

    Lauter, Roland; Brendel, Christian; Habraken, Steven J M; Marquardt, Florian

    2015-07-01

    Arrays of coupled limit-cycle oscillators represent a paradigmatic example for studying synchronization and pattern formation. We find that the full dynamical equations for the phase dynamics of a limit-cycle oscillator array go beyond previously studied Kuramoto-type equations. We analyze the evolution of the phase field in a two-dimensional array and obtain a "phase diagram" for the resulting stationary and nonstationary patterns. Our results are of direct relevance in the context of currently emerging experiments on nano- and optomechanical oscillator arrays, as well as for any array of coupled limit-cycle oscillators that have undergone a Hopf bifurcation. The possible observation in optomechanical arrays is discussed briefly. PMID:26274242

  1. A design concept for an MMIC (Monolithic Microwave Integrated Circuit) microstrip phased array

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Smetana, Jerry; Acosta, Roberto

    1987-01-01

    A conceptual design for a microstrip phased array with monolithic microwave integrated circuit (MMIC) amplitude and phase controls is described. The MMIC devices used are 20 GHz variable power amplifiers and variable phase shifters recently developed by NASA contractors for applications in future Ka proposed design, which concept is for a general NxN element array of rectangular lattice geometry. Subarray excitation is incorporated in the MMIC phased array design to reduce the complexity of the beam forming network and the number of MMIC components required.

  2. Local phase control for a planar array of fiber laser amplifiers

    NASA Astrophysics Data System (ADS)

    Steffanic, Patrick; Johannes, Benjamin T.; Sison, Claudia A.; Hughes, Gary B.; Lubin, Philip; Meinhold, Peter; Suen, Jonathan; O'Neill, Hugh; Kangas, Miikka; Brashears, Travis; Zhang, Qicheng; Griswold, Janelle; Riley, Jordan; Motta, Caio

    2015-09-01

    Arrays of phase-locked lasers have been developed for numerous directed-energy applications. Phased-array designs are capable of producing higher beam intensity than similar sized multi-beam emitters, and also allow beam steering and beam profile manipulation. In phased-array designs, individual emitter phases must be controllable, based on suitable feedback. Most current control schemes sample individual emitter phases, such as with an array-wide beam splitter, and compare to a master phase reference. Reliance on a global beam splitter limits scalability to larger array sizes due to lack of design modularity. This paper describes a conceptual design and control scheme that relies only on feedback from the array structure itself. A modular and scalable geometry is based on individual hexagonal frames for each emitter; each frame cell consists of a conventional lens mounted in front of the fiber tip. A rigid phase tap structure physically connects two adjacent emitter frame cells. A target sensor is mounted on top of the phase tap, representing the local alignment datum. Optical sensors measure the relative position of the phase tap and target sensor. The tap senses the exit phase of both emitters relative to the target normal plane, providing information to the phase controller for each emitter. As elements are added to the array, relative local position data between adjacent phase taps allows accurate prediction of the relative global position of emitters across the array, providing additional constraints to the phase controllers. The approach is scalable for target distance and number of emitters without loss of control.

  3. Quarterly Research Performance Progress Report (2015 Q3). Ultrasonic Phased Arrays and Interactive Reflectivity Tomography for Nondestructive Inspection of Injection and Production Wells in Geothermal Energy Systems

    SciTech Connect

    Santos-Villalobos, Hector J; Polsky, Yarom; Kisner, Roger A; Johnson, Christi R; Collins, Case; Bouman, Charles; Abdulrahman, Hani; Foster, Benjamin

    2015-09-01

    For the past quarter, we have placed our effort in implementing the first version of the ModelBased Iterative Reconstruction (MBIR) algorithm, assembling and testing the electronics, designing transducers mounts, and defining our laboratory test samples. We have successfully developed the first implementation of MBIR for ultrasound imaging. The current algorithm was tested with synthetic data and we are currently making new modifications for the reconstruction of real ultrasound data. Beside assembling and testing the electronics, we developed a LabView graphic user interface (GUI) to fully control the ultrasonic phased array, adjust the time-delays of the transducers, and store the measured reflections. As part of preparing for a laboratory-scale demonstration, the design and fabrication of the laboratory samples has begun. Three cement blocks with embedded objects will be fabricated, characterized, and used to demonstrate the capabilities of the system. During the next quarter, we will continue to improve the current MBIR forward model and integrate the reconstruction code with the LabView GUI. In addition, we will define focal laws for the ultrasonic phased array and perform the laboratory demonstration. We expect to perform laboratory demonstration by the end of October 2015.

  4. A Ku band 5 bit MEMS phase shifter for active electronically steerable phased array applications

    NASA Astrophysics Data System (ADS)

    Sharma, Anesh K.; Gautam, Ashu K.; Farinelli, Paola; Dutta, Asudeb; Singh, S. G.

    2015-03-01

    The design, fabrication and measurement of a 5 bit Ku band MEMS phase shifter in different configurations, i.e. a coplanar waveguide and microstrip, are presented in this work. The development architecture is based on the hybrid approach of switched and loaded line topologies. All the switches are monolithically manufactured on a 200 µm high resistivity silicon substrate using 4 inch diameter wafers. The first three bits (180°, 90° and 45°) are realized using switched microstrip lines and series ohmic MEMS switches whereas the fourth and fifth bits (22.5° and 11.25°) consist of microstrip line sections loaded by shunt ohmic MEMS devices. Individual bits are fabricated and evaluated for performance and the monolithic device is a 5 bit Ku band (16-18 GHz) phase shifter with very low average insertion loss of the order of 3.3 dB and a return loss better than 15 dB over the 32 states with a chip area of 44 mm2. A total phase shift of 348.75° with phase accuracy within 3° is achieved over all of the states. The performance of individual bits has been optimized in order to achieve an integrated performance so that they can be implemented into active electronically steerable antennas for phased array applications.

  5. Multifunctional transducer

    NASA Technical Reports Server (NTRS)

    Feldstein, C.; Lewis, G. W.; Culler, V. H.; Merrbaum, S. (Inventor)

    1981-01-01

    Several parameters of a small region of a muscle tissue or other object, can be simultaneously measured using with minimal traumatizing or damage of the object, a trifunctional transducer which can determine the force applied by a muscle fiber, the displacement of the fiber, and the change in thickness of the fiber. The transducer has three legs with inner ends joined together and outer ends formed to piece the tissue and remain within it. Two of the legs are relatively stiff, to measure force applied by the tissue, and a third leg is relatively flexible to measure displacement of the tissue relative to one or both stiff legs, and with the three legs lying in a common plane so that the force and displacement measurements all relate to the same direction of muscle movements. A flexible loop is attached to one of the stiff legs to measure changes in muscle thickness, with the upper end of the loop fixed to the leg and the lower end of the loop bearing against the surface of the tissue and being free to slide on the leg.

  6. Ultrasonic Air-Coupled Inspection of Textile Materials Using Ferroelectret-Based Phased Arrays

    NASA Astrophysics Data System (ADS)

    Ealo, J.; Camacho, J.; Seco, F.; Fritsch, C.

    2010-02-01

    Most common defects in textile manufacturing processes include weaving errors (such as missing threads), oil spots and material inhomogeneities. In this work, we demonstrate the feasibility of using ferroelectret-based transducers for the inspection of woven material. A linear array of 32 elements was built for this purpose following an easy fabrication procedure recently proposed. Electronic focusing at the textile sample position allowed us to detect weaving errors and oil spots of up to ˜1 mm of width in through transmission mode, at normal incidence and with a good signal-to-noise ratio.

  7. COST EFFECTIVE SEAWATER DESALINATION WITH ICP ELEMENT ARRAYS - PHASE I

    EPA Science Inventory

    Okeanos Technologies is developing a desalination system that uses Ion Concentration Polarization (ICP) elements and modular arrays. ICP can separate water from solutes and contaminants far more efficiently than reverse osmosis (RO) or electrodialysis (ED) because no extrem...

  8. MEMS ultrasonic transducer for monitoring of steel structures

    NASA Astrophysics Data System (ADS)

    Jain, Akash; Greve, David W.; Oppenheim, Irving J.

    2002-06-01

    Ultrasonic methods can be used to monitor crack propagation, weld failure, or section loss at critical locations in steel structures. However, ultrasonic inspection requires a skilled technician, and most commonly the signal obtained at any inspection is not preserved for later use. A preferred technology would use a MEMS device permanently installed at a critical location, polled remotely, and capable of on-chip signal processing using a signal history. We review questions related to wave geometry, signal levels, flaw localization, and electromechanical design issues for microscale transducers, and then describe the design, characterization, and initial testing of a MEMS transducer to function as a detector array. The device is approximately 1-cm square and was fabricated by the MUMPS process. The chip has 23 sensor elements to function in a phased array geometry, each element containing 180 hexagonal polysilicon diaphragms with a typical leg length of 49 microns and an unloaded natural frequency near 3.5 MHz. We first report characterization studies including capacitance-voltage measurements and admittance measurements, and then report initial experiments using a conventional piezoelectric transducer for excitation, with successful detection of signals in an on-axis transmission experiment and successful source localization from phased array performance in an off-axis transmission experiment.

  9. Recent developments in monolithic phase-locked semiconductor laser arrays

    NASA Technical Reports Server (NTRS)

    Katz, J.; Kapon, E.; Margalit, S.; Yariv, A.

    1984-01-01

    Coherent combination of the power of several semiconductor lasers fabricated on the same substrate has been the subject of an intense research effort in recent years, the main motivation being to obtain higher power levels than those available from a single laser in a stable radiation pattern. Best results reported so far include 2.6 watts CW emitted power and less than 1 deg far-field angle (in the array plane) in arrays where all the lasers are electrically connected in parallel. A different type of coherent array, where each element has a separate contact, has been recently demonstrated. While requiring the more complex two-level metallization technology, applying a separate contact to each laser provides an additional degree of freedom in the design and the operation of monolithic arrays. The separate contacts can be employed to tailor the near-field and far-field distributions and to compensate for device-to-device nonuniformities. Furthermore, the control of the currents of the array elements allows the performance of a variety of other functions, such as beam scanning, spectral mode control, wavelength tuning and control of the mutual coherence between array elements.

  10. Recent developments in monolithic phase-locked semiconductor laser arrays

    NASA Technical Reports Server (NTRS)

    Katz, J.; Kapon, E.; Margalit, S.; Yariv, A.

    1984-01-01

    Coherent combination of the power of several semiconductor lasers fabricated on the same substrate has been the subject of an intense research effort in recent years, the main motivation being to obtain higher power levels than those available from a single laser in a stable radiation pattern. Best results reported so far include 2.6 Watts CW emitted power and less than 1 deg far-field angle (in the array plane) in arrays where all the lasers are electrically connected in parallel. A different type of coherent array, where each element has a separate contact, has been recently demonstrated. While requiring the more complex two-level metallization technology, applying a separate contact to each laser provides an additional degree of freedom in the design and the operation of monolithic arrays. The separate contacts can be employed to tailor the near-field and far-field distributions and to compensate for device-to-device nonuniformities. Furthermore, the control of the currents of the array elements allows the performance of a variety of other functions, such as beam scanning, spectral mode control, wavelength tuning and control of the mutual coherence between array elements.

  11. Monolithic optical integrated control circuitry for GaAs MMIC-based phased arrays

    NASA Technical Reports Server (NTRS)

    Bhasin, K. B.; Ponchak, G. E.; Kascak, T. J.

    1985-01-01

    Gallium arsenide (GaAs) monolithic microwave integrated circuits (MMIC's) show promise in phased-array antenna applications for future space communications systems. Their efficient usage will depend on the control of amplitude and phase signals for each MMIC element in the phased array and in the low-loss radiofrequency feed. For a phased array contining several MMIC elements a complex system is required to control and feed each element. The characteristics of GaAs MMIC's for 20/30-GHz phased-array systems are discussed. The optical/MMIC interface and the desired characteristics of optical integrated circuits (OIC's) for such an interface are described. Anticipated fabrication considerations for eventual full monolithic integration of optical integrated circuits with MMIC's on a GaAs substrate are presented.

  12. Phased-array antenna control by a monolithic photonic integrated circuit, COMPASS

    SciTech Connect

    Kravitz, S.H.; Hietala, V.M.; Vawter, G.A.; Meyer, W.J.

    1991-01-01

    Phased-array antenna systems are well known for rapid beam steering and their ability to bring high power to the target. Such systems are also quite complex and heavy, which have limited their usefulness. The issues of weight, size, power use, and complexity have been addressed through a system named COMPASS (Coherent Optical Monolithic Phased Array Steering System). All phased-array antenna systems need: (1) small size; (2) low power use; (3) high-speed beam steering; and (4) digitally-controlled phase shifting. COMPASS meets these basic requirements, and provides some very desirable additional features. These are: (1) phase control separate from the transmit/receive module; (2) simple expansion to large arrays; (3) fiber optic interconnect for reduced sensitivity to EMI; (4) an intrinsically radiation-hard GaAs chip; and (5) optical power provided by a commercially available continuous wave (CW) laser. 4 refs., 8 figs.

  13. Pulse-Echo Phased Array Ultrasonic Inspection of Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS)

    NASA Technical Reports Server (NTRS)

    Johnston, Pat H.

    2010-01-01

    A PRSEUS test article was subjected to controlled impact on the skin face followed by static and cyclic axial compressions. Phased array ultrasonic inspection was conducted before impact, and after each of the test conditions. A linear phased array probe with a manual X-Y scanner was used for interrogation. Ultrasound showed a delamination between the skin and stringer flange adjacent to the impact. As designed, the stitching in the flange arrested the lateral flaw formation. Subsequent ultrasonic data showed no delamination growth due to continued loading. Keywords: Phased Array, Ultrasonics, Composites, Out-of-Autoclave

  14. Iterative optimization of phase-only diffractive optical elements based on a lenslet array.

    PubMed

    Arrizón, V; Testorf, M; Sinzinger, S; Jahns, J

    2000-12-01

    We describe the design of Fourier-type phase-only array generators. The numerical optimization employs the Fienup algorithm, where the parageometric design of the phase retardation profile, with the form of a lenslet array, is used as the initial guess of the optimization process. This approach provides designs with high performance that can be obtained with comparatively low computing effort. This is particularly true for elements generating large spot arrays. For symmetric reconstruction fields, the optimized phase profile typically has the same symmetry as that for the reconstruction field and can be easily unwrapped. PMID:11140474

  15. A portable ultrasonic phased array device for tabular joint weld inspection of offshore platform structures

    NASA Astrophysics Data System (ADS)

    Shan, Baohua; Li, Jingan; Duan, Zhongdong; Ou, Jinping; Shen, Wei

    2012-05-01

    To meet the inspection need for complex tabular joints weld of offshore platform structures, a portable ultrasonic phased array inspection device is developed. The integrated device is small and portable. As designed, the device can implement different algorithm of the ultrasonic phased array inspection technology. With proposed inspection plan, the experiment of Y tubular joint model was performed in lab. Experiment results indicate that the possible ultrasonic phased array inspection device can detect and visualize the flaws on Y tubular joint weld, which are nearly consistent with the actual condition.

  16. Atmospheric Array Loss Statistics Derived from Short Time Scale Site Test Interferometer Phase Data

    NASA Astrophysics Data System (ADS)

    Morabito, David D.; D'Addario, Larry R.

    2014-08-01

    NASA is interested in using the technique of arraying smaller-diameter antennas to increase effective aperture to replace the aging 70-m-diameter antennas of the Deep Space Network (DSN). Downlink arraying using the 34-m-diameter and 70-m-diameter antennas is routinely performed. Future scenarios include extending the technique to uplink arraying where a downlink signal may not be available. Atmospheric turbulence causes decorrelation of the arrayed signal, and becomes more severe at higher frequencies such as at the uplink allocations near 34 GHz and 40 GHz. This article expands the study initiated in a previous article that focused on average array loss statistics extracted from Site Test Interferometer (STI) data. In that study, cumulative distributions of the annual and monthly expected phasing loss were derived from STI data collected at the Goldstone and Canberra DSN complexes. For a two-element array, the average array loss cannot exceed 3 dB. This article considers the instantaneous (short time scale) array loss that sometimes exceeds 3 dB for a two-element array. We also consider cases of three-element arrays, which behave somewhat differently. The short time scale statistics of array loss at 7.15 GHz and 34.5 GHz are compared against the average array loss statistics for the best-case and worst-case weather months for the Goldstone and Canberra DSN sites.

  17. Optimization of the Geometric Phase Sensitivity of an Array of Atom Ring Interferometers

    NASA Astrophysics Data System (ADS)

    Sandoval-Sanchez, Karina; Campo, Christian; Rivera, Tabitha; Toland, John

    2015-05-01

    Sagnac, and Aharonov-Bohm phase shifts are important geometric phase shifts in atom interferometry. These phase shifts characterize rotational and magnetic field interference effects respectively. Theoretical explorations have shown that a series of ring interferometers can be connected in series to increase the sensitivity of the overall device while keeping the maximum path separation less than the coherence length of the atoms. It has also been shown that the application of an area chirp to the rings will further enhance the sensitivity of the array of rings to geometric phase shifts. Area chirp refers to characterizing all of the rings in the array to a fixed percentage of a reference ring, this allows for the phase shifts in each ring to be characterized by one ring. The goal of this project is to determine a set of parameters namely kL, the product of the ring circumference and the wave number and γ, the chirp factor for the area chirp, that optimize the geometric phase sensitivity for an array of N rings. We model the transmission coefficient of a quantum matter wave through an area chirped array of interferometers as a function of phase, using transfer matrices to represent the transmission and reflection of individual rings in the array. Isolated transmission resonances represent the domain of interest, these are regions of high phase sensitivity. After optimizing a ring array without loss we apply velocity broadening to the input matter waves to investigate a more realistic output.

  18. Design and fabrication of a high temperature leading edge heating array, phase 1

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Progress during a Phase 1 program to design a high temperature heating array is reported for environmentally testing full-scale shuttle leading edges (30 inch span, 6 to 15 inch radius) at flight heating rates and pressures. Heat transfer analyses of the heating array, individual modules, and the shuttle leading edge were performed, which influenced the array design, and the design, fabrication, and testing of a prototype heater module.

  19. Ultra wideband photonic control of an adaptive phased array antenna

    NASA Astrophysics Data System (ADS)

    Cox, Joseph L.; Zmuda, Henry; Li, Jian; Sforza, Pasquale M.

    2006-05-01

    This paper presents a new concept for a photonic implementation of a time reversed RF antenna array beamforming system. The process does not require analog to digital conversion to implement and is therefore particularly suited for high bandwidth applications. Significantly, propagation distortion due to atmospheric effects, clutter, etc. is automatically accounted for with the time reversal process. The approach utilizes the reflection of an initial interrogation signal from off an extended target to precisely time match the radiating elements of the array so as to re-radiate signals precisely back to the target's location. The backscattered signal(s) from the desired location is captured by each antenna and used to modulate a pulsed laser. An electrooptic switch acts as a time gate to eliminate any unwanted signals such as those reflected from other targets whose range is different from that of the desired location resulting in a spatial null at that location. A chromatic dispersion processor is used to extract the exact array parameters of the received signal location. Hence, other than an approximate knowledge of the steering direction needed only to approximately establish the time gating, no knowledge of the target position is required, and hence no knowledge of the array element time delay is required. Target motion and/or array element jitter is automatically accounted for. This paper presents the preliminary study of the photonic processor, analytical justification, and simulated results. The technology has a broad range of applications including aerospace and defense and in medical imaging.

  20. Frequency translating phase conjugation circuit for active retrodirective antenna array. [microwave transmission

    NASA Technical Reports Server (NTRS)

    Chernoff, R. (Inventor)

    1980-01-01

    An active retrodirective antenna array which has central phasing from a reference antenna element through a "tree" structured network of transmission lines utilizes a number of phase conjugate circuits (PCCs) at each node and a phase reference regeneration circuit (PRR) at each node except the initial node. Each node virtually coincides with an element of the array. A PCC generates the exact conjugate phase of an incident signal using a phase locked loop which combines the phases in an up converter, divides the sum by 2 and mixes the result with the phase in a down converter for phase detection. The PRR extracts the phase from the conjugate phase. Both the PCC and the PRR are not only exact but also free from mixer degeneracy.

  1. Characteristics of block-periodic phased-array antennas with circular polarization of the radiated field

    NASA Astrophysics Data System (ADS)

    Likhoded, Iu. V.; Mironnikov, A. S.

    1990-02-01

    The paper presents results of a numerical investigation of the directivity characteristics of a block-periodic waveguide phased-array antenna with circular polarization of the radiated field. The advantages of this array from the viewpoint of maximining the ellipticity coefficent of the radiated field in the scanning sector are pointed out.

  2. Optical phased array using single crystalline silicon high-contrast-gratings for beamsteering

    NASA Astrophysics Data System (ADS)

    Yoo, Byung-Wook; Chan, Trevor; Megens, Mischa; Sun, Tianbo; Yang, Weijian; Rao, Yi; Horsley, David A.; Chang-Hasnain, Connie J.; Wu, Ming C.

    2013-03-01

    We present a single crystalline silicon optical phased array using high-contrast-gratings (HCG) for fast two dimensional beamforming and beamsteering at 0.5 MHz. Since there are various applications for beamforming and beamsteering such as 3D imaging, optical communications, and light detection and ranging (LIDAR), it is great interest to develop ultrafast optical phased arrays. However, the beamsteering speed of optical phased arrays using liquid crystal and electro-wetting are typically limited to tens of milliseconds. Optical phased arrays using micro-electro-mechanical systems (MEMS) technologies can operate in the submegahertz range, but generally require metal coatings. The metal coating unfortunately cause bending of mirrors due to thermally induced stress. The novel MEMS-based optical phased array presented here consists of electrostatically driven 8 × 8 HCG pixels fabricated on a silicon-on-insulator (SOI) wafer. The HCG mirror is designed to have 99.9% reflectivity at 1550 nm wavelength without any reflective coating. The size of the HCG mirror is 20 × 20 μm2 and the mass is only 140 pg, much lighter than traditional MEMS mirrors. Our 8 × 8 optical phased array has a total field of view of +/-10° × 10° and a beam width of 2°. The maximum phase shift regarding the actuation gap defined by a 2 μm buried oxide layer of a SOI wafer is 1.7π at 20 V.

  3. Millimeter-Wave Photonics for Communications and Phased Arrays

    NASA Astrophysics Data System (ADS)

    Nanzer, Jeffrey A.; Wichman, Adam; Klamkin, Jonathan; McKenna, Timothy P.; Clark, Thomas R.

    2015-07-01

    This article presents recent developments in millimeter-wave communications architectures featuring broadband photonic signal generation, up-conversion and down-conversion, as well as true-time-delay photonic steering of millimeter-wave arrays. These developments will support future high-capacity millimeter-wave wireless communications by enabling broadband signals to be generated and converted between baseband and millimeter-wave carrier frequencies without electronic heterodyne systems and by permitting the use of true-time-delay beamsteering in millimeter-wave array apertures.

  4. New customizable phased array UT instrument opens door for furthering research and better industrial implementation

    SciTech Connect

    Dao, Gavin; Ginzel, Robert

    2014-02-18

    Phased array UT as an inspection technique in itself continues to gain wide acceptance. However, there is much room for improvement in terms of implementation of Phased Array (PA) technology for every unique NDT application across several industries (e.g. oil and petroleum, nuclear and power generation, steel manufacturing, etc.). Having full control of the phased array instrument and customizing a software solution is necessary for more seamless and efficient inspections, from setting the PA parameters, collecting data and reporting, to the final analysis. NDT researchers and academics also need a flexible and open platform to be able to control various aspects of the phased array process. A high performance instrument with advanced PA features, faster data rates, a smaller form factor, and capability to adapt to specific applications, will be discussed.

  5. Development of components for an S-band phased array antenna subsystem

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The system requirements, module test data, and S-band phased array subsystem test data are discussed. Of the two approaches to achieving antenna gain (mechanically steered reflector or electronically steered phased array), the phased array approach offers the greatest simplicity and lowest cost (size, weight, power, and dollars) for this medium gain. A competitive system design is described as well as hardware evaluation which will lead to timely availability of this technology for implementing such a system. The objectives of the study were: to fabricate and test six engineering model transmit/receive microelectronics modules; to design, fabricate, and test one dc and logic multilayer manifold; and to integrate and test an S-band phased array antenna subsystem composed of antenna elements, seven T/R modules, RF manifolds and dc manifold.

  6. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Satellite Communications Terminal, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  7. Phased Array Ultrasonic Sound Field Mapping in Cast Austenitic Stainless Steel

    SciTech Connect

    Crawford, Susan L.; Prowant, Matthew S.; Cinson, Anthony D.; Larche, Michael R.; Diaz, Aaron A.; Anderson, Michael T.

    2014-05-31

    This study maps the phased array-generated acoustic sound fields through three types of CASS microstructure in four specimens to quantitatively assess the beam formation effectiveness in these materials.

  8. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Electric Substation, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  9. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Civil Engineering Storage Building, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  10. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Techinical Equipment Building, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  11. Free space optical communication link using a silicon photonic optical phased array

    NASA Astrophysics Data System (ADS)

    Rabinovich, William S.; Goetz, Peter G.; Pruessner, Marcel; Mahon, Rita; Ferraro, Mike S.; Park, Doe; Fleet, Erin; DePrenger, Michael J.

    2015-03-01

    Many components for free space optical communication systems have shrunken in size over the last decade. However, the steering systems have remained large and power hungry. Non-mechanical beam steering offers a path to reducing the size of these systems. Optical phased arrays can allow integrated beam steering elements. One of the most important aspects of an optical phased array technology is its scalability to a large number of elements. Silicon photonics can potentially offer this scalability using CMOS foundry techniques. In this paper a small-scale silicon photonic optical phased array is demonstrated for both the transmitter and receiver functions in a free space optical link. The device using an array of thermo-optically controlled waveguide phase shifters and demonstrates one-dimensional steering with a single control electrode. Transmission of a digitized video data stream over the link is shown.

  12. Beale Air Force Base, Perimeter Acquisition Vehicle Entry PhasedArray Warning ...

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

    Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Microwave Equipment Building, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  13. Phased Array Ultrasonic Examination of Space Shuttle Main Engine Nozzle Weld

    NASA Technical Reports Server (NTRS)

    James, S.; Engel, J.; Kimbrough, D.; Suits, M.; McCool, Alex (Technical Monitor)

    2001-01-01

    This paper describes a Phased Array Ultrasonic Examination that was developed for the examination of a limited access circumferential Inconel 718 fusion weld of a Space Shuttle Main Engine Nozzle - Cone. The paper discusses the selection and formation criteria used for the phased array focal laws, the reference standard that simulated hardware conditions, the examination concept, and results. Several unique constraints present during this examination included limited probe movement to a single axis and one-sided access to the weld.

  14. An Update on Phased Array Results Obtained on the GE Counter-Rotating Open Rotor Model

    NASA Technical Reports Server (NTRS)

    Podboy, Gary; Horvath, Csaba; Envia, Edmane

    2013-01-01

    Beamform maps have been generated from 1) simulated data generated by the LINPROP code and 2) actual experimental phased array data obtained on the GE Counter-rotating open rotor model. The beamform maps show that many of the tones in the experimental data come from their corresponding Mach radius. If the phased array points to the Mach radius associated with a tone then it is likely that the tone is a result of the loading and thickness noise on the blades. In this case, the phased array correctly points to where the noise is coming from and indicates the axial location of the loudest source in the image but not necessarily the correct vertical location. If the phased array does not point to the Mach radius associated with a tone then some mechanism other than loading and thickness noise may control the amplitude of the tone. In this case, the phased array may or may not point to the actual source. If the source is not rotating it is likely that the phased array points to the source. If the source is rotating it is likely that the phased array indicates the axial location of the loudest source but not necessarily the correct vertical location. These results indicate that you have to be careful in how you interpret phased array data obtained on an open rotor since they may show the tones coming from a location other than the source location. With a subsonic tip speed open rotor the tones can come form locations outboard of the blade tips. This has implications regarding noise shielding.

  15. Phased laser array with tailored spectral and coherence properties

    DOEpatents

    Messerly, Michael J; Dawson, Jay W; Beach, Raymond J

    2011-03-29

    Architectures for coherently combining an array of fiber-based lasers are provided. By matching their lengths to within a few integer multiples of a wavelength, the spatial and temporal properties of a single large laser are replicated, while extending the average or peak pulsed power limit.

  16. Phased laser array with tailored spectral and coherence properties

    SciTech Connect

    Messerly, Michael J; Dawson, Jay W; Beach, Raymond J

    2014-05-20

    Architectures for coherently combining an array of fiber-based lasers are provided. By matching their lengths to within a few integer multiples of a wavelength, the spatial and temporal properties of a single large laser are replicated, while extending the average or peak pulsed power limit.

  17. Inferential statistics for transient signal detection in radio astronomy phased arrays

    NASA Astrophysics Data System (ADS)

    Schmid, Natalia A.; Prestage, Richard M.; Alkhweldi, Marwan

    2015-05-01

    In this paper we develop two statistical rules for the purpose of detecting pulsars and transients using signals from phased array feeds installed on a radio telescope in place of a traditional horn receiver. We assume a known response of the antenna arrays and known coupling among array elements. We briefly summarize a set of pre-processing steps applied to raw array data prior to signal detection and then derive two detection statistics assuming two models for the unknown radio source astronomical signal: (1) the signal is deterministic and (2) the signal is a random process. The performance of both detectors is analyzed using both real and simulated data.

  18. Optical modeling for a laser phased-array directed energy system

    NASA Astrophysics Data System (ADS)

    Hughes, Gary B.; Lubin, Philip; Griswold, Janelle; Cook, Brianna; Bozzini, Durante; O'Neill, Hugh; Meinhold, Peter; Suen, Jonathan; Bible, Johanna; Riley, Jordan; Johansson, Isabella E.; Pryor, Mark; Kangas, Miikka

    2014-09-01

    We present results of optical simulations for a laser phased array directed energy system. The laser array consists of individual optical elements in a square or hexagonal array. In a multi-element array, the far-field beam pattern depends on both mechanical pointing stability and on phase relationships between individual elements. The simulation incorporates realistic pointing and phase errors. Pointing error components include systematic offsets to simulate manufacturing and assembly variations. Pointing also includes time-varying errors that simulate structural vibrations, informed from random vibration analysis of the mechanical design. Phase errors include systematic offsets, and time-varying errors due to both mechanical vibration and temperature variation in the fibers. The optical simulation is used to determine beam pattern and pointing jitter over a range of composite error inputs. Results are also presented for a 1 m aperture array with 10 kW total power, designed as a stand-off system on a dedicated asteroid diversion/capture mission that seeks to evaporate the surface of the target at a distance of beyond 10 km. Phase stability across the array of λ/10 is shown to provide beam control that is sufficient to vaporize the surface of a target at 10 km. The model is also a useful tool for characterizing performance for phase controller design in relation to beam formation and pointing.

  19. A study program on large aperture electronic scanning phased array antennas for the shuttle imaging microwave system

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Fundamental phased array theory and performance parameters are discussed in terms of their application to microwave radiometry, and four scanning phased arrays representing current examples of state-of-the-art phased array technology are evaluated for potential use as components of the multispectral antenna system for the space shuttle imaging microwave system (SIMS). A discussion of problem areas, both in performance and fabrication is included, with extrapolations of performance characteristics for phased array antennas of increased sizes up to 20 m by 20 m. The possibility of interlacing two or more phased arrays to achieve a multifrequency aperture is considered, and, finally, a specific antenna system is recommended for use with SIMS.

  20. Optical phased array using high-contrast grating all-pass filters for fast beam steering

    NASA Astrophysics Data System (ADS)

    Yang, Weijian; Sun, Tianbo; Rao, Yi; Chan, Trevor; Megens, Mischa; Yoo, Byung-Wook; Horsley, David A.; Wu, Ming C.; Chang-Hasnain, Connie J.

    2013-03-01

    A novel 8x8 optical phased array based on high-contrast grating (HCG) all-pass filters (APFs) is experimentally demonstrated with high speed beam steering. Highly efficient phase tuning is achieved by micro-electro-mechanical actuation of the HCG to tune the cavity length of the APFs. Using APF phase-shifters allows a large phase shift with an actuation range of only tens of nanometers. The ultrathin HCG further ensures a high tuning speed (0.626 MHz). Both one-dimensional and two-dimensional HCGs are demonstrated as the actuation mirrors of the APF arrays with high beam steering performance.

  1. Blue-phase liquid crystal cored optical fiber array with photonic bandgaps and nonlinear transmission properties.

    PubMed

    Khoo, Iam Choon; Hong, Kuan Lung; Zhao, Shuo; Ma, Ding; Lin, Tsung-Hsien

    2013-02-25

    Blue-phase liquid crystal (BPLC) is introduced into the pores of capillary arrays to fabricate fiber arrays. Owing to the photonic-crystals like properties of BPLC, these fiber arrays exhibit temperature dependent photonic bandgaps in the visible spectrum. With the cores maintained in isotropic as well as the Blue phases, the fiber arrays allow high quality image transmission when inserted in the focal plane of a 1x telescope. Nonlinear transmission and optical limiting action on a cw white-light continuum laser is also observed and is attributed to laser induced self-defocusing and propagation modes changing effects caused by some finite absorption of the broadband laser at the short wavelength regime. These nonlinear and other known electro-optical properties of BPLC, in conjunction with their fabrication ease make these fiber arrays highly promising for imaging, electro-optical or all-optical modulation, switching and passive optical limiting applications. PMID:23481965

  2. Phase aligner for the Electronically Scanned Thinned Array Radiometer (ESTAR) instrument

    NASA Technical Reports Server (NTRS)

    Chren, William A., Jr.; Zomberg, Brian G.

    1993-01-01

    A prototype Phase Aligner (PA) or the Electronically Scanned Thinned Array Radiometer instrument has been designed and tested. Implemented in a single Xilinx XC3042PC84-125 Field Programmable Gate Array (FPGA), it is a dual-port register file which allows independent storage and phase coherent retrieval of antenna array data by the Central Processing Unit (CPU). It has dimensions of 4 x 20 bits and can be used at clock frequencies as high as 25 MHz. The ESTAR is a passive synthetic-aperture radiometer designed to sense soil moisture and ocean salinity at L-band.

  3. Efficient structures for geosynchronous spacecraft solar arrays, phase 4

    NASA Technical Reports Server (NTRS)

    Adams, L. R.

    1982-01-01

    Efficient structures for geosynchronous spacecraft solar arrays were investigated. The STACBEAM (stacking triangular articulated compact beam) concept was selected. The primary component, the solar array blanket, is stored in a folded configuration and is deployed by controlled linear extension. Blanket stiffness is attained by axially tensioning the blanket and by providing periodic lateral ribs and standoffs which attach the blanket to the beam at several places along its length. The STACBEAM deploys sequentially (one bay at a time) using a deployer of sufficient rigidity so that beam stiffness is not degraded during deployment. The beam does not rotate during deployment, thus making blanket beam attachment possible in the packaged condition. In addition to high bending stiffness, the STACBEAM possesses high torsional rigidity due to nonflexible diagonals. The concept is adaptable to various size and loading requirements by changing member diameter and baylength, thus affecting the ratio of packaged and deployed length.

  4. MIMO based optical phased array technology with electronic beam steering for laser radar applications

    NASA Astrophysics Data System (ADS)

    Sharma, Neha; Zmuda, Henry

    2010-04-01

    This paper will address the analysis and design of an electronically scanned phased array laser radar (ladar) system utilizing the techniques of multi-input multi-output (MIMO) array design. MIMO radar is has attracted much attention recently from both researchers and practitioners alike due to its significant potential for advancing the state-of-the-art RF radar technology. The laser radar architecture presented stands to gain significant inroads on the ability to apply RF array processing methods to laser radar systems in several ways. Specifically, using MIMO array design concepts, it is shown that the resolution of the ladar array can substantially exceed the diffraction limited resolution of a conventional array. Additionally, the use of array methods provides the capability to electronically steer the aperture, thus avoiding the mechanical beam scanning methods generally encountered in laser radar systems. Finally, by using an array of radiators, an increase in total radiated power is achieved, relieving the power burden on a single laser. The problems traditionally encountered in applying conventional array techniques to laser/detector arrays, for example, the inability to achieve half-wavelength spacing or the surfacing of source coherence issues, actually work to one's advantage when viewed in the MIMO paradigm. It is anticipated that the successful implementation of this system will significantly advance the state-of-the-art of laser radar capabilities for high speed imaging, target detection, tracking, and signature analysis.

  5. Piezoelectric phased array acousto-ultrasonic interrogation of damage in thin plates

    NASA Astrophysics Data System (ADS)

    Purekar, Ashish S.

    the damaged region. The presence of the reflected waves and the attenuation of the incident wave in the transmission case indicates that damage is present in the structure. A reflected wave can be used to infer the location of damage on a structure. A phased array technique is used which isolates the source of these reflections in an effort to identify the damage location. (Abstract shortened by UMI.)

  6. Ballast-mounted PV arrays: Phase 2 final report

    SciTech Connect

    Edward C. Kern

    2000-03-01

    The expansive flat rooftops of industrial and commercial buildings across America offer the largest, most secure, and potentially least-cost real estate opportunity to install massive amounts of solar photovoltaic generation in the building sector. Unfortunately, mechanical penetration of roofing membranes is very expensive and perceived by building owners and operators to increase the likelihood of leaking. In response Ascension Technology has pioneered the development of low-cost ballasted approaches for mounting PV arrays. Recently, however, we have experienced our first two instances in which strong winds have moved our arrays on rooftops and heightened our interest, and the PV industries' need, to develop zero-penetration mounting techniques that are more secure, yet remain low in cost. In this PV BONUS project, Ascension Technology and its partners addressed wind loading on solar panels and the suitability of using frictional forces between ballast trays and roofing materials to resist PV arrays sliding on rooftops. The primary goal of the project is to capture the potential cost savings made possible by ballast-mounting by showing under what conditions it can satisfy wind loading concerns. A secondary goal is to address a more geographically constrained concern regarding withstanding seismic forces.

  7. Thermal infrared array, phase 1. Volume 1: Technical

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The recommended design configuration for the focal plane array of a 1,000 element linear pushbroom system consists of 32 modules; the complete configuration is built by butting together two 1024 linear arrays. Each of the linear arrays is formed by edge butting 16 modules together. By staggering the modules of the two rows, the channel outages which occur where the modules are edge butted can be eliminated. Two stages TDI operation is performed by the post processing electronics, which reduces the design complexity of the focal plane. Systems studies show that: (1) a single focal plane design can satisfy both the LEO and SEOS mission configurations; (2) available optical designs can meet mission goals; (3) MTF can be traded with optical complexity in a future study; (4) a chopping mechanism can be devised to modifying modulate radiation to a 4-inch focal plane as well as insert two calibration sources at the required frequencies for chopping and calibration; (5) radiative cooling technology should be suitable for a future sensor in either mission configuration; and (6) cold shielding is not a requirement.

  8. Resonant-Cavity-Induced Phase Locking of a Josephson Array

    NASA Astrophysics Data System (ADS)

    Almaas, E.; Stroud, D.

    2001-03-01

    In this talk, we will present a dynamical model for an underdamped Josephson junction array coupled to a resonant microwave cavity. This is a generalization of earlier work(J. K. Harbaugh and D. Stroud, Phys. Rev. B 61), 14765 (2000). where mean-field properties were studied. We numerically solve the model in one dimension and show that (i) at fixed disorder and strength of the coupling to the resonant cavity, the array locks into a coherent, periodic state above a critical number Nc of active Josephson junctions; (ii) the current-voltage characteristics of the array exhibit self-induced resonant steps (SIRS), similar to Shapiro steps; and (iii) when Na active junctions are synchronized on a SIRS, the energy radiated into the resonant cavity is a quadratic function of N_a. All three features are in excellent agreement with results from a recent experiment (P. Barbara, A. B. Cawthorne, S. V. Shitov, and C. J. Lobb, Phys. Rev. Lett. 82), 1963 (1999). where a remarkably high degree of dc to ac power conversion was achieved.

  9. Array Automated Assembly Task Low Cost Silicon Solar Array Project, Phase 2

    NASA Technical Reports Server (NTRS)

    Rhee, S. S.; Jones, G. T.; Allison, K. L.

    1978-01-01

    Progress in the development of solar cells and module process steps for low-cost solar arrays is reported. Specific topics covered include: (1) a system to automatically measure solar cell electrical performance parameters; (2) automation of wafer surface preparation, printing, and plating; (3) laser inspection of mechanical defects of solar cells; and (4) a silicon antireflection coating system. Two solar cell process steps, laser trimming and holing automation and spray-on dopant junction formation, are described.

  10. Spatially Defined Oligonucleotide Arrays. Technical Report for Phase II

    SciTech Connect

    2000-06-15

    The goal of the Human Genome Project is to sequence all 3 billion base pairs of the human genome. Progress in this has been rapid; GenBank{reg_sign} finished 1994 with 286 million bases of sequence and grew by 2470 in the first quarter of 1995. The challenge to the scientific community is to understand the biological relevance of this genetic information. In most cases the sequence being generated for any single region of the genome represents the genotype of a single individual. A complete understanding of the function of specific genes and other regions of the genome and their role in human disease and development will only become apparent when the sequence of many more individuals is known. Access to genetic information is ultimately limited by the ability to screen DNA sequence. Although the pioneering sequencing methods of Sanger et al. (15) and Maxam and Gilbert (11) have become standard in virtually all molecular biology laboratories, the basic protocols remain largely unchanged. The throughput of this sequencing technology is now becoming the rate-limiting step in both large-scale sequencing projects such as the Human Genome Project and the subsequent efforts to understand genetic diversity. This has inspired the development of advanced DNA sequencing technologies (9), Incremental improvements to Sanger sequencing have been made in DNA labeling and detection. High-speed electrophoresis methods using ultrathin gels or capillary arrays are now being more widely employed. However, these methods are throughput-limited by their sequential nature and the speed and resolution of separations. This limitation will become more pronounced as the need to rapidly screen newly discovered genes for biologically relevant polymorphisms increases. An alternative to gel-based sequencing is to use high-density oligonucleotide probe arrays. Oligonucleotide probe arrays display specific oligonucleotide probes at precise locations in a high density, information-rich format (5

  11. Solid-state retrodirective phased array concepts for microwave power transmission from Solar Power Satellite

    NASA Technical Reports Server (NTRS)

    Schroeder, K. G.; Petroff, I. K.

    1980-01-01

    Two prototype solid-state phased array systems concepts for potential use in the Solar Power Satellite are described. In both concepts, the beam is centered on the rectenna by means of phase conjugation of a pilot signal emanating from the ground. Also discussed is on-going solid-state amplifier development.

  12. Application of adaptive optics to scintillation correction in phased array high-frequency radar

    NASA Astrophysics Data System (ADS)

    Theurer, Timothy E.; Bristow, William A.

    2015-06-01

    At high frequency, diffraction during ionospheric propagation can yield wavefronts whose amplitude and phase fluctuate over the physical dimensions of phased array radars such as those of the Super Dual Auroral Radar Network (SuperDARN). Distortion in the wavefront introduces amplitude and phase scintillation into the geometric beamformed signal while reducing radar performance in terms of angular resolution and achieved array gain. A scintillation correction algorithm based on adaptive optics techniques is presented. An experiment conducted using two SuperDARN radars is presented that quantifies the effect of wavefront distortion and demonstrates a reduction in observed scintillation and improvement in radar performance post scintillation correction.

  13. Laser-ablative engineering of phase singularities in plasmonic metamaterial arrays for biosensing applications

    SciTech Connect

    Aristov, Andrey I.; Kabashin, Andrei V.; Zywietz, Urs; Evlyukhin, Andrey B.; Reinhardt, Carsten; Chichkov, Boris N.

    2014-02-17

    By using methods of laser-induced transfer combined with nanoparticle lithography, we design and fabricate large-area gold nanoparticle-based metamaterial arrays exhibiting extreme Heaviside-like phase jumps in reflected light due to a strong diffractive coupling of localized plasmons. When employed in sensing schemes, these phase singularities provide the sensitivity of 5 × 10{sup 4} deg. of phase shift per refractive index unit change that is comparable with best values reported for plasmonic biosensors. The implementation of sensor platforms on the basis of such metamaterial arrays promises a drastic improvement of sensitivity and cost efficiency of plasmonic biosensing devices.

  14. Number of phase levels in a two-dimensional separable Talbot array illuminator.

    PubMed

    Zhao, S; Zhou, C; Xi, P; Wang, H; Liu, L

    2001-01-01

    The number of phase levels in a Talbot array illuminator (TAIL) is an important factor for estimation of practical fabrication complexity and cost. We show that the number of phase levels in a two-dimensional TAIL (2D-TAIL) has a simple relation to the prime number. When the output array is alternatively pi phase modulated, there are similar simple relations. These simple relations should be highly interesting for practical use. An experiment with the 2D-TAIL based on the joint-Talbot effect is given as well. PMID:11151985

  15. A novel technique for electronic phasing of high power fiber amplifier arrays

    NASA Astrophysics Data System (ADS)

    Shay, T. M.; Baker, J. T.; Sanchez, Anthony D.; Robin, C. A.; Vergien, C. L.; Zeringue, C.; Gallant, D.; Lu, Chunte A.; Pulford, Benjamin; Bronder, T. J.; Lucero, Arthur

    2009-06-01

    We report high power phase locked fiber amplifier array using the Self-Synchronous Locking of Optical Coherence by Single-detector Electronic-frequency Tagging technique. We report the first experimental results for a five element amplifier array with a total locked power of more than 725-W. We will report on experimental measurements of the phase fluctuations versus time when the control loop is closed. The rms phase error was measured to be λ/60. Recent results will be reported. To the best of the authors' knowledge this is the highest fiber laser power to be coherently combined.

  16. Fabrication and Testing of Binary-Phase Fourier Gratings for Nonuniform Array Generation

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Crow, Robert W.; Ashley, Paul R.; Nelson, Tom R., Jr.; Parker, Jack H.; Beecher, Elizabeth A.

    2004-01-01

    This effort describes the fabrication and testing of binary-phase Fourier gratings designed to generate an incoherent array of output source points with nonuniform user-defined intensities, symmetric about the zeroth order. Like Dammann fanout gratings, these binary-phase Fourier gratings employ only two phase levels to generate a defined output array. Unlike Dammann fanout gratings, these gratings generate an array of nonuniform, user-defined intensities when projected into the far-field regime. The paper describes the process of design, fabrication, and testing for two different version of the binary-phase grating; one designed for a 12 micron wavelength, referred to as the Long-Wavelength Infrared (LWIR) grating, and one designed for a 5 micron wavelength, referred to as the Mid-Wavelength Infrared Grating (MWIR).

  17. Phase-rotation based receive-beamformer for miniaturized volumetric ultrasound imaging scanners using 2-D CMUT-on-ASIC arrays

    NASA Astrophysics Data System (ADS)

    Kim, Bae-Hyung; Lee, Seunghun; Song, Jongkeun; Kim, Youngil; Jeon, Taeho; Cho, Kyungil

    2013-03-01

    Up-to-date capacitive micromachined ultrasonic transducer (CMUT) technologies provide us unique opportunities to minimize the size and cost of ultrasound scanners by integrating front-end circuits into CMUT arrays. We describe a design prototype of a portable ultrasound scan-head probe using 2-D phased CMUT-on-ASIC arrays of 3-MHz 250 micrometer-pitch by fabricating and integrating front-end electronics with 2-D CMUT array elements. One of the objectives of our work is to design a receive beamformer architecture for the smart probe with compact size and comparable performance. In this work, a phase-rotation based receive beamformer using the sampling frequency of 4 times the center frequency and a hybrid beamforming to reduce the channel counts of the system-side are introduced. Parallel beamforming is considered for the purpose of saving power consumption of battery (by firing fewer times per image frame). This architecture has the advantage of directly obtaining I and Q components. By using the architecture, the interleaved I/Q data from the storage is acquired and I/Q demodulation for baseband processing is directly achieved without demodulators including sin and cosine lookup tables and mixers. Currently, we are extending the presented architecture to develop a true smart probe by including lower power devices and cooling systems, and bringing wireless data transmission into consideration.

  18. Transducer-Mounting Fixture

    NASA Technical Reports Server (NTRS)

    Spiegel, Kirk W.

    1990-01-01

    Transducer-mounting fixture holds transducer securely against stud. Projects only slightly beyond stud after installation. Flanged transducer fits into fixture when hinged halves open. When halves reclosed, fixture tightened onto threaded stud until stud makes contact with transducer. Knurled area on fixture aids in tightening fixture on stud.

  19. Transducer of linear displacements

    NASA Astrophysics Data System (ADS)

    Malamed, Y. R.

    1984-02-01

    The basic PLP transducer is designed for a UIM-29 microscope and a 2-coordinate measuring instrument with electronic digital readout. Its optical system consists of an AL-107B light-emitting diode as light source, two condenser lenses, a special wedge carrying two pairs of joined receiver lenses, a prism-mirror, a photoreceiver, a wedge-shape transparent replica of a twin diffraction grating which prevents light reflected by the air-glass interface from focusing on the receiver photodiodes, and a reflective replica of a diffraction grating on a movable carriage. The already available three models of this transducer are PLP1-0.2, PLP1-0.5, and PLP1-1.0 with respectively 625, 250, 125 lines/mm on the transparent replica and respectively 312.5, 125, 62.5 lines/mm on the reflective replica. The scale of moire-interference fringes characterizing the shift between both diffraction gratings per grating period (9.16 mm in each model) is respectively 0.8, 2.0, 4.0 microns and the angle between the two arrays of grating lines on the transparent replica is respectively 36 + or - 4 deg, 90 + or - 10 deg, 190 + or - 20 deg.

  20. Controlled fundamental supermode operation of phase-locked arrays of gain-guided diode lasers

    NASA Technical Reports Server (NTRS)

    Kapon, E.; Margalit, S.; Yariv, A.; Katz, J.

    1984-01-01

    Uniform semiconductor laser arrays tend to oscillate in a superposition of their supermodes, thus leading to large beam divergence and spectral spread. Discrimination among the supermodes in phase-locked arrays is discussed theoretically. It is shown that supermode discrimination in gain-guided arrays, in favor of the fundamental supermode, is made possible by the near-field interference patterns which result from the complex optical fields of the gain-guided lasers. A fundamental supermode operation is demonstrated, for the first time, in GaAlAs/GaAs gain-guided laser arrays. This is achieved by control of the current (gain) profile across the array by means of individual laser contacts.